A PROJECT REPORT

ON

DISTRIBUTION OF TRACE METALS AND NUTRIENTS IN

RIVERINE ESTUARINE AND ADJOINING COASTAL WATERS AND

SEDIMENTS OF RIVER PERIYAR AND ARABIAN SEA

BY

PROF. K.C. MATHEW. MSc.M.Phil

C.M.S. COLLEGE, KOTTAYAM

DECEMBER 2016

ACKNOWLEDGEMENT

I express my sincere gratitude to the Principal, CMS college

Kottayam for recommending my name to avail this UGC project.

I am highly indebted to the Director, School of Marine Sciences,

CUSAT for providing the facilities to conduct the project.

I place my deep-felt gratitude to the UGC for releasing the financial

Aid to do this project and make it a grant success.

Kottayam Prof.K.C.Mathew. M.Sc. M.Phil

December 2016

CONTENTS

PAGE NO

CHAPTER I INTRODUCTION 1

CHAPTER II MATERIALS AND METHODS 12

SUMMARY 82

CONCLUSION 88

REFERENCES 108

1

CHAPTER 1

INTRODUCTION

Marine Chemistry has been arousing the curiosity of scientists since the

beginning of the last century , for it unveils the mysteries of oceans and their

impacts on human civilization. The entire Hydrosphere represents a system of

dynamic equilibrium between the saline water of the sea and estuaries, fresh

water input from rivers , solid supply from land, the atmosphere, the aquatic

organisms, dissolved and suspended matter and bottom sediments. Basically,

the aquatic environment is strongly interlinked between riverine, estuarine and

marine systems, of which estuaries represent a transitional stage from river to

sea. From the dawn of history, rivers and estuaries have drawn attention as

centers of civilization due to the vast industrial and agricultural activities, and

coastal zones due to the fishing and harbour activities. The oceans constitute

about 98% of the hydrosphere and are the ultimate sink into which all wastes of

land and most of that in air are dropped. This has resulted in the total disruption

of the natural equilibrium existing in the hydrosphere. The entire aquatic system

of the world has become incredibly polluted due to the various complex

activities of mankind. It is in this context that the study of the characteristic

features of the aquatic system has assumed utmost importance, of which the

study of distribution of trace metals takes a major role. The present study

involves the evaluation of concentration and distribution pattern of trace

metals, and the various biogeochemical processes influencing the distribution.

1.1 ELEMENTS IN SEA WATER

Sea water may be considered as an aqueous solution containing a number

of dissolved solids, gases and suspended matter of both organic and

2

inorganic origin. The total amount of dissolved materials is generally

expressed in terms of salinity. Salinity has been assigned an average value

of 35 x 10-3

. The dissolved constituents are broadly classified into major

elements and minor elements. By convention, those elements which are

present above 1 p.p.m or less are called minor elements. The major ions are

said to be “ conservative ” in the sense that their concentration in sea water

bear a constant ratio, one to another whereas the minor elements are not

conservative in nature. Barth (1952) has introduced the concept of

Residence time of an element, which is the average time it remains in the

sea before being removed by various physical, chemical and biological

processes.

1.2 CHEMICAL SPECIATION

The term ‘ species’, implies the actual form in which a molecule or ion is

present in solution. Chemical speciation studies in its wider sense include

species analysis, species distribution, species reactivity and species

transformation.

Goldberg (1954) and Krauskopt (1956) were among the first to conduct

speciation studies. Sillen (1961) developed the application of equilibrium

models to the portrayal of many aspects of the species composition of sea

water. Chemical speciation is largely influenced by changes in the salinity,

ionic strength and PH resulting from mixing of water from different

environments.

In an environment an element may occur just as a single molecular

species or in many molecular species. The chemical reactivity of an element

depends on the chemical species in which it is present. The most abundant

species may not always be the most reactive one. The chemical speciation of

the metal together with the reaction involved in the transformation of

3

species is often the factor determining the extent to which the metal can

affect the aquatic environment (Forstner and Wittmann, 1983). The

environment impact of trace metals more or less depends on the different

physical and chemical species which are present than on the total metal

concentration.

1.3 TRACE ELEMENTS IN NATURAL WATERS.

The ‘minor elements’ or ‘Trace elements’ are those which exist in the sea at

1.p.pm. or less excluding the nutrients, dissolved gases and radioactive

elements (Bruland, 1983). Trace element is also defined as one which

normally occurs at concentration level below 100mg Kg -1

(100 p.p.m) of

the dry weight of the organism (Ronald, 1981). For practical purposes, the

terms such as ‘Trace Metals’ ‘Trace Inorganics’, ‘Heavy Metals,

Microelements and Micronutrients are treated as synonymous with the term

‘Trace Element’ (Wittmann, 1983).

Most of the minor elements are not conservative in sea water mainly

because of the their greater geochemical and biological reactivity and partly

because of adsorption, biological uptake, unusual localized concentration

from river run off and volcanic action.

The trace elements are introduced into the sea by various mechanisms.

Run off from land is the principal path way. A major portion of trace

metals, adsorbed on suspended detrital matter are displaced by action of

major cations of sea water. Trace metals enter the sea by leaching of the

rock flour’. Trace metals like Zn,Cu,Mn found in geological waters are

found to be of volcanic origin. Garrels and Mackenzie (1971) have

estimated that 2.5 x 1016

g of material are added to the oceans every year of

which about 90% contribution is from rivers (2.25 x 1016

g yr-1

). Other

mechanisms of the input of trace metals include industrial activities,

4

locally important sources like dust storms found at Australian and African

coasts, atmospheric dust flux etc.

Scavenging of trace elements from the deep sea has often been attributed

to adsorption onto fine particle surfaces (Bruland, 1983). The subsequent

setting of these particles, (Bacon and Anderson, 1982). or their

incorporation into large fast sinking particles, leads to their vertical removal.

Clay minerals and Iron and Manganese Oxides provide surfaces for

adsorption ( Balistrieri and Murray, 1981). The adsorptive properties of

these surfaces are likely to be modified by the presence of organic films

(Balistrieri et al., 1981; Hunter 1983). Biological removal such as by

plankton inorganic process such as absorption and precipitation are also

significant.

1.4 DISSOLVED AND PARTICULATE

The distinction between particulate and dissolved matter in sea is arbitrary

and depends somewhat on the filter used (Strickland and Parsons, 1972).

When sea water is filtered using a 0.45µm . filter, the fraction which passes

through the filter is considered as dissolved and retained are called the

particulate (APHA, 1985). The dissolved species quite often include most of

the colloidal forms of the element. The physical, chemical, biological and

geological processes cause generation of particulate matter. The suspended

matter vary appreciably in composition and amount and with respect to

seasonal changes. River run off, coastal erosion, resuspension of sediments,

decay of biological matters, redox reactions near water sediment boundary

etc. lead to the formation of particulate matter (Feeby et al., 1986)

In the river water a fraction of the trace metal exists as a colloid by

physico-chemical association with colloidal humic acid and hydrous iron

5

oxides. The major processes in the estuarine region are desorption,

flocculation and sedimentation (Bourg, 1983).

The Inorganic fraction of the suspended particulate matter consists of

minerals such as feldspars, clay, quartz formed by weathering of terrestrial

rocks and siliceous and calcareous remains of dead organisms. The organic

particulate matter consists of living organisms, their decay and metabolic

products. An appreciable amount of trace elements such as iron and copper

are adsorbed onto them or held in organic combination as chelates or in

porphyrins.

The concentration of trace elements in the particulate form may be

slightly higher at the bottom than the surface, owing to the resuspension of

sediment by currents (Riley and Chester, 1971)

Transport of metals from rivers and estuaries is dependent on the

partitioning of metals between dissolved and particulate phases. The

partitioning is modified by several factors: specific metal ion, metal

concentration, nature of particulate, particulate concentration. PH , salinity

and dissolved oxygen. Suspended particulate matter may consist of

biological, organic and mineral phases that will each contain different co-

ordination sites to bind metals (Stumm, 1992). The partitioning of a metal

between particulate and dissolved is commonly quantified in terms of the

distribution co-efficient KD ( Benoit, 1994).

– Mass of part. metal / mass of total part.

KD =

Mass of diss. metal/ Vol. of water

High particle reactivity for a metal would increase that metal’s KD value.

As KD is a measure of the tendency of an element to be associated and

6

transported with particulate phase it is an important factor in geochemical

modelling.

1.5 INTERACTION BETWEEN DISSOLVED AND PARTICULATE

Interaction between dissolved and particulate fractions occur, in all the three

aquatic environments, riverine, estuarine and marine waters. Basically, there

are three methods by which this may take place.

1. Precipitation of dissolved material to give new solid phases

2. Uptake of dissolved material in to solid phases already present such as

lithogenous minerals, living and detrital organic material.

3. The release of material into solution from particulate phase by dissolution,

desorption, autolyptic and respiratory biological processes.

When trace metals transported by rivers enter estuarine waters, they are

brought to an entirely different environment with different physical and

chemical characteristics, similar thing happens between estuarine and marine

waters. The change of environments will affect the relative distribution of

metals and their chemical speciation between dissolved and particulate

forms. For example, (Aston and Chester, 1973_) have found that

Fe(111)removal was more rapid at higher salinities.

1.6 EFFECT OF TRACE METALS ON ORGANISMS

The impact of trace metals on the marine organisms is one of the

extensively studied subject and much research has been going on in this

direction. It has been proved experimentally that marine plants and animals

require specific amounts of different types of trace elements for their growth,

maintenance and other life processes. These include Iron, Manganese,

Molybdenum, Zinc, Copper, Cobalt and Vanadium. Reviewing the subject,

Bowen (1985) has put forward certain generalizations. They include (1) the

7

order of affinity of organisms to cations increases with cationic charge (2) the

heavier elements in a particular group of the periodic table are taken up more

strongly than the lighter (3) the affinity for anions increases with ionic charge

etc. It has been demonstrated that many of the marine organisms contain trace

elements at concentrations as high as 106 times their sea water concentrations.

Usually, lower organisms concentrate trace elements more strongly than do

higher ones.

Marine organisms may concentrate trace elements not only in their

tissues, but also in the skeletal parts, which may consist of hydrous silicon

dioxide, Calcium Carbonate, Iron oxides, Calcium fluorophosphates or

strontium sulphate (Lowenstam, 1963). Trace metals are selectively

concentrated in organic and inorganic phases. Thus metals like Zn, Cu, La, etc

are present in organic phases (Arrhenius , 1963).

The roles played by many of the metals have been established. Thus, Iron

plays an important part in the light reactions of photosynthesis in the form of

complex ferrodoxin. Manganese is present in the enzyme co-factors involved in

photosynthesis and also in nitrate reduction. Cu complexes serve as co-factors

in oxidation reduction cycles (Riley and Chester, 1971)

The concentration of an element in readily available species, rather than its total

concentration is important in controlling growth (Spencer, 1957). Very little is

known about concentration of trace elements required by phytoplankton. The

actual amount required vary from species to species. However the concentration

of trace metal available in the sea is more than sufficient to sustain the optimum

rate of photosynthesis (Mc Allister et. al., 1961). It has been proved that trace

metals at high concentrations can become toxic and hinder growth (Thomas &

Siebert, 1971) But very low concentrations can inhibit their growth and affect

vital functions (Anderson et al., 1978)

8

Recent investigations on the trace metal concentrations in selected fish

and invertebrates have shown that the excess concentrations of metals like Cu.

Zn. Cr etc on such organisms are immensely toxic to their life (Ambrose et al.,

(2001); Sadiq, 1992) As a result of metal – binding properties macro – algae

have been considered suitable for use as biomonitors of trace metals (Leal et al.,

1997)

1.7 FERRO – MANGANESE NODULES

Ferro – Manganese nodules are large sources of Fe and Mn, grown in

bulbous appearance and are distributed in deep sea sediments in the ocean floor.

They are common in Pacific and Indian oceans and they cover between 20 to

50% of the pelagic sea floor in the south western Pacific.

They have a specific gravity of approximately 2.4 and are porous in

nature. The main structural elements of the nodules include at least three

manganese oxide and hydroxide minerals viz. 8 MnO2 , and two forms of

manganese (11) manganite, ie, 7 A0 – Manganite and 10 A

0 –Manganite. In

cross-section, they display an alternating concentrtic series of light and dark

bands ( Arrhenius, 1963). The average composition of nodules in terms of

weight percent is : Mn – 25, Fe-15, Ni-1, Co-0.5, Cu – 0.5, Pb – 0.1. Zn – 0.1

and Cr – 0.001 . Manganese nodules vary in metal composition, size, shape and

occurance. Nearshore nodules contain lower amounts of metals than those in

deeper waters. They grow in layers at an average rate of about 1 m.m per

thousand years. According to Mero (1965) the total deposit in the oceans is

about 7 trillion tons.

9

1.8 BEHAVIOUR OF TRACE METALS IN RIVERINE, ESTUARINE

AND MARINE ENVIRONMENTS.

An estuary is a semi enclosed coastal body of water which has free connection

with the open sea and within which sea water is measurably diluted with fresh

water derived from land drainage (Pritchard, 1967). It is the region where sea

water is mixed with fresh water derived from land, to produce a wide range of

brackish waters of intermediate salinity. Estuaries are geochemical reactors and

their heterogeneous reactions determine the fate of metals of continental origin

in the oceans (Francois, 1994).Trace metals can behave either conservatively or

non- concervatively during estuarine mixing because they depend upon various

physico – chemical factors like pH, Eh, suspended solids, ionic strength etc. The

exchange reactions play a major role in the behavior and transport of trace

metals in estuaries (Forstner et al., 1990). Hydrogenous precipitation of Iron

and Manganese oxides in the low salinity region also influence the behaviur of

trace metals. Colloidal particles can act as scavengers of trace metals dependent

on climate conditions, the transport of Heavy metals is highly dependent on

climatic conditions and the nature of river discharge (Dash and Sahu, 1999).

The large variation in trace metal concentrations observed in estuarine systems

reflect the extreme dynamics and complexity of these environments. (Benoit,

1994 ).

A study on the distribution of heavy metals in sea water is very important

to understand their role in various biogeochemical processes of the sea. In the

marine waters, the different processes controlling metal distribution tend to be

super imposed. Inputs can be from rivers, sediments, atmosphere and

degradation of materials formed in situ, Removal can be by biological uptake,

sorption in or onto the sedimentary particles, both organic and inorganic and by

flushing with oceans and coastal waters (Kremling et.al., 1998). Further, a

knowledge of the distribution and concentrations of heavy metals in marine

10

water helps to detect the sources of pollution in aquatic system and hence trace

metal analysis acts as one of the marine pollution programmes ( Govindasamy

et al., 1998). Trace metals are magnified in the food chain and reach human

beings causing deleterious effects (Nitta, 1992). Plankton, one of the basic food

resources in marine system, are known to concentrate heavy metals in large

quantities. They play an active role in the removal of metals from the ambient

sea water and also act as an indicator for marine pollution (Sampathkumr and

Kannan, 1994).

The distribution of trace metals in riverine water appears to be rather

complex because due to various environmental factors each river shows unique

properties and general conclusions cannot be drawn so easily. Rivers may

change pH and redox potential in the course of a season or even a day. The

experimental approach to speciation and residence time works best in fresh

water since ionic strength is so much less than in estuarine and sea waters. The

importance of organic materials in the trace metal budget of river waters have

been examined and found that most of the trace metals are complexed with

organic matter in either soluble or colloidal form with no detectable ionic metals

present. Mantoura et al., (1978) found that more than 90% of Copper and

Mercury in fresh water are complexed by humic materials. The adsorption of

trace metals was studied by Vuceta and Morgan (1978) and showed that the

speciation and partitioning between dissolved and particulate fractions have

been strongly affected by adsorption on organic materials.

AIM AND SCOPE OF THE PRESENT STUDY

River Periyar, Cochin Estuary and adjoining coastal areas of Arabian sea have

been regions of intense research to study the distribution pattern of trace metals,

Major elements, Organic and Inorganic nutrients and the influence of

hydrographical parameters on them, for the past few decades. Since it is a

11

multi diamentional probe pertaining to several environmental climatic and

physico- chemical parameters involving a multitude of biochemical processes,

studies done hitherto were only partial or focusing only on a few components.

This work envisages a broad approach to the subject taking into consideration

three different aquatic environments viz. riverine, estuarine and marine water

bodies and their characterization in three different seasonal variations, viz. Pre

monsoon, Monsoon and Post monsoon periods. A comprehensive study of this

kind has not been done so far. Five different samples were collected from five

locations on each environment on a monthly basis, trifurcated and averaged

into three major seasonal divisions. The pre monsoon period extends from

February to May, the monsoon period from June to Septembe, the post monsoon

period from October to January.

The distribution pattern of trace metals like Fe, Mn, Cu, Cd, Co, Cr,

Pb,and Hg in water and sediments, nutrients like Nitrate, Phosphate,

Ammonium, Silicate and hydro graphical parameters like salinity, pH, dissolved

Oxygen, Temperature etc., have become the subject of detailed investigation

and the correlation between metals, metals and nutrients, metals and

hydrographical parameters were explored at length. Based on the findings, a

comparison was made between the above mentioned water bodies and similar

ones on a worldwide basis in relation to seasonal fluctuations and an attempt

has been made to locate and predict the index of pollution encountered in this

region which would bring to light the precautionary measures to be undertaken

by the common masses and government authorities in the years to come.

12

CHAPTER II

MATERIALS AND METHODS

2.1 SAMPLING AND STORAGE

Water samples were collected in acid washed polythene bottles. Two Litre

polythene bottles were soaked in 1 Normal Nitric acid overnight and thoroughly

washed with deionized double distilled water. Surface water sample were

collected using acid cleaned plastic buckets. Bottom water samples were

collected by using a high tech water sampler. Samples for the determination of

salinity were collected in salinity bottles and those for the dissolved oxygen

determination in 50 ml Dissolved Oxygen bottles. Samples were collected from

both surface and bottom.

2.2 METHODS OF ANALYSIS

2.2.1. HYDROGRAPHIC PARAMETERS

The distribution pattern of trace metals is largely influenced by

hydrographic parameters of the aquatic environment. The important

hydrographic parameters are salinity, dissolved oxygen, temperature, pH etc.

The determination of Hydrographic Parameters were carried out along with

trace metal analysis and the methods adopted are outlined below.

2.2.1.1 DETERMINATION OF SALINITY

Salinity was estimated argentometrically by the Mohr – Knudsen method

(Grasshoff et al., 1983). The method is based on the reaction in which the halide

is treated with a standard solution of Silver Nitrate. In a neutral or slightly

alkaline solution, Potassium Chromate can indicate the end point of the Silver

Nitrate titration with a halide.

2..2.1.2 DETERMINATION OF DISSOLVED OXYGEN

13

Dissolved Oxygen was determined by Winkler’s method (Strickland and

Parsons; 1977). The principle of this method is based on a set of chemical

reactions in which the physically dissolved oxygen is chemically bound by

Manganese (II) hydroxide in a strong alkaline medium. Mn (II) is oxidized to

Mn (III) . After the complete precipitation of the mixed Mn (II) and Mn (III),

the sample is acidified to the PH between 1 and 2.5. The Mn (III) ions liberated

react with previously added lodate. The lodine liberated is titrated with standard

Sodium Thiosulphate solution.

2.2.1.3 DETERMINATION OF TEMPERATURE

The temperature was measured by an ordinary graded Mercury –

in - glass thermometer, immediately after the samples were collected.

2.2.1.4 DETERMINATION OF pH

The PH of the water samples was determined using a Systronix Digital P

H

meter, model 335. The pH

is directly read from the pH meter.

2.3 TREATMENT OF SAMPLES FOR TRACE METAL ANALYSIS

The dissolved fraction of metals is that fraction of an unacidified sample

that passes through a 0.45 µm Whatmann membrane filter. The particulate

fraction of metals is that fraction retained by 0.45 µm filter.The “total metal”

contents is the concentration of metals determined on the unfiltered sample after

vigorous digestion or the sum of the concentrations of metals in both dissolved

and particulate fractions.

FILTRATION

The water samples were filtered through a 0.45 µm filter using a

Milipore filter apparatus. The filtrate was acidified by Con. HNO3 to a pH

2 and

14

stored in refrigeration till the analysis. The particulate retained on the filters

were dried at 500C and cooled in a dessicator to a constant weight.

2.3.1 TRACE METAL ANALYSIS

Standard procedures as described by Daniellsson et al., (1983) for Atomic

Absorption Spectrometry and APHA (1985) for acid Digestion were adopted in

this study.

2.5.1.1 DISSOLVED METAL

The filtrate was thoroughly defrozen and subjected to solvent extraction

using APDC – CHCl3 (Ammonium 1-pyrrolidine dithiocarbomate –

chloroform) and the metal content was determined by AAS

REAGENTS

(1) APDC – An aqueous solution of 2% (W/V) APDC was freshly

prepared on the day of analysis

(2) Citrate Buffer – An aqeous solution of 10% Diammonium hydrogen

Citrate was prepared.

(3) Chloroform – Chloroform of ultra pure quality was used for the

analysis

(4) Nitric Acid – Concentrated Nitric Acid of ultra pure quality was used

for the analysis.

(5) Standard metal solution – Standard metal stock solutions (pH 2) of

I gdm-3

were prepared From this solutions working standards of 10-4

to 10-6

m

dm-3

(pH

-2were prepared by quantitative dilution, according to sample

concentrations.

15

PROCEDURE

One litre of the water sample was transferred to a two litre separating

funnel. The pH of the sample was adjusted to about 4.5 by the addition of 10 cc

citrate buffer. 10 ml of APDC solution was added, followed by 50 ml

chloroform. The mixture was shaken for about 2 minutes, kept for about 15

minutes to separate the two phases. The lower organic layer was drained into a

250 ml separating funnel. The extraction was continued by the addition of

another 50 ml chloroform and shaken for 2 minutes. Repeated this process once

more, and the three portions were combined and 2 ml concentrated Nitric acid

added by means of a micro pipette. After mixing for 1 minute, the funnel was

allowed to stand for about 15 minutes to decompose the metal carbomates.

Added 5-8 ml of purest water and shaken for about 2 minutes to ensure

complete back extraction. After the phases had been separated, the lower

chloroform layer was discarded. The acid phase containing the back extracted

metal was then drained into a 25 ml beaker and the 250 ml separating funnel

was rinsed twice with 5 ml purest water. The total extract was evaporated to

dryness, preferably on a ceramic hot plate and in a clean air fume – hood. The

residue in the beaker was then redissolved in warm one molar Nitric acid and

quantitatively transferred to a 25 ml standard flask. It was then transferred to

polyethylene vials for later analysis by AAS.

ANALYSIS OF SEDIMENTS

Textural characteristics of sediments were determined using pipette

analysis. The sediments were finely powdered and dried at approximately 700C

and were digested in a mixture of HF-HCl04 – HNO3 and treated with 0.5 M

HCl solution so as to get about 25 ML in Milli –Q water.

16

17

RIVER PERIYAR

River Periyar is the longest of all rivers in Kerala and is abouit 300 kms

in length (244 kms in Kerala). It originates from the Sivagiri peaks (1800 m

MSL) of Sundara Mala in Tamil Nadu. It has a catchment area of 5396 sq.kms

(5284 sq. Kms in Kerala ) The total annual flow is estimated to be 11607 cubic

meters. There are two important tributaries for the river namely Idamalayar and

puyamkutty which supply a large quantity of sediment load at all seasons. The

major portion of the sediment is thrown out into the Bhuthathankettu reservoir.

Flowing with its tributaries, the river joins with the Vembanad lake at

Azhikode.

Angamali to Kochi occupies the most industrialized zone of the periyar

River basin. There are over 50 large and medium industries and over 2500

small scale industries in this region. The industries located in Edayar – Eloor

area consumes about 189343 cum per day water from the river and discharges

about 75% as used water along with large quantity of effluents and pollutants .

The major types of these industries are fertilizers, pesticides, chemicals, and

allied industries, petroleum refining and heavy metal processing, radio active

mineral processing, rubber processing units, animal bone processing units,

battery manufacturers, Mercury products, acid manufacturers, pigment and latex

producers etc. The wide spectra of pollutants that adversely affect the natural

environmental quality of water of the river include toxic and hazardous

materials such as heavy metals, phenolics, hydrocarbons, pesticides,

radionuclides, ammonia, phosphates, domestic and untreated waste water.

Preliminary studies on the trace metal distribution by Paul and Pillai

(1976) revealed that higher concentrations are observed at downstream

locations than in the upstream regions. Elevated concentrations of Cu,Zn,and

18

Cd were observed near Binani Zinc and Travancore Cochin Chemicals Ltd

(TCC) were some of the highlights of the data.

Periyar is gradually undergoing eco degradation due to anthropogenic

stresses, which include indiscriminate deforestation, domestic – agricultural –

industrial water pollution, excessive exploitation of resources, large scale sand

mining, interferences in water flow etc.

COCHIN ESTUARY

The Cochin Estuary, the longest on the west coast of Kerala state extends

between (90

40´ - 10010´N and 76

0 15´ - 76

0 30´ - E) the cities of Azhikode in

the north and Alleppy in the south, running parallel to the Arabian sea. It has a

length of about 70 kms and a width varying between a few hundred meters to

about 6 kms. It covers an area of approximately 300 km2 and falls under the

category of a tropical positive estuary. The Estuary is connected to theArabian

sea through a permanent opening, the barmouth at Cochin and two seasonal

openings, one at Andhakaranazhy and another at Azhikode. The Cochin

Estuary is generally wide (0.8 – 1.5 kms) and deep (4 – 13 m) towards south but

becomes narrow (0.05 – 0.5 km) and shallow (0.5 – 3.0m) in its northern part.

Six rivers (Pampa, Achancovil, Manimala, Meenachil, Periyar and

Muvattupuzha) with their tributaries along with several canals, bring large

volumes of freshwater into the estuary. Among these rivers, Periyar (from

North) and Muvattupuzha (from south) discharge into the estuarine system and

hence have an active influence on the prevailing salinity of the Cochin Estuary.

Tidal intrusion from Arabian sea contributes a regular flow of salt water, which

diminishes considerably towards the head of the estuary.

19

DISTRIBUTION OF HYDROGRAPHIC PARAMETERS

1. DISTRIBUTION OF SALINITY

Knudsen (1901) has defined salinity as the weight in grams of the total

dissolved inorganic matter in 1 kg of sea water after all bromide and iodide have

been replaced by the equivalent amount of chloride and all the carbonate

converted to oxide. The total salt content of sea water is about 0.45% greater

than its salinity defined in this way.

Many of the physical properties of sea water , viz. density, refractive index,

conductivity do depend on salinity. The determination of salinity has been

carried out for all the months in the pre-monsoon, monsoon and post monsoon

season for all the three aquatic environments, viz, marine, estuarine and riverine

waters for both surface and bottom waters. The experimental observations are

presented in the table I

In the riverine system a minimum of 1.5 and a maximum of 2.00 were

noticed . In the estuarine system a minimum value of 3.2 and a max of 4.2 were

observed. In the marine system a minimum of 35.6 and a maximum value of 38

were noticed. In all the three aquatic environments the bottom water showed

greater salinity than surface waters.

The data sets for the Riverine, estuarine and marine waters are the most

comprehensive and are used to illustrate the monthly variations. The variations

in coastal water is attributed to freshwater flow, tidal flow, wave and wind

intensity and direction. The variations in salinity can influence the distribution

pattern of trace metal concentrations too. The Periyar River sites showed

minimum salinity of surface waters in the middle of the dry season. As can be

expected, higher levels of salinity occurred in the late dry seasons. The

combinations of high tidal flows and intense wave actions control the salinity

values in the near – shore areas. However the bottom waters show increased

values of salinity due to desorption from suspended particulate matter and

inflow of inter stitial waters. In the off-shore area, the salinity variations are

20

less pronounced compared to in-shore, both in surface and bottom waters. There

were increases in salinity in the middle and late dry seasons and a lower salinity

in the beginning of the wet season. Continuously logged in situ physico –

chemical data from the river mouth showed that daily tidal influences are

significant.

21

DISTRIBUTION OF SALINITY TABLE I

RIVERINE ESTUARINE MARINE

1.

2.

3.

4.

5.

S - 1.5

B - 1.6

S - 1.6

B - 1.6

S - 1.5

B - 1.7

S - 1.5

B - 1.7

S - 1.7

B - 1.7

1.

2.

3.

4.

5.

S - 3.2

B - 3.3

S - 3.2

B - 3.5

S - 3.5

B - 3.7

S - 3.5

B - 4.1

S - 3.6

B - 4.2

1.

2.

3.

4.

5.

S - 35

B - 35.6

S - 35.6

B - 35.7

S - 35.7

B - 35.8

S - 35.6

B - 35.8

S - 35.7

B - 35.8

PR

EM

ON

SO

ON

1.

2.

3.

4.

5.

S - 1.5

B - 1.6

S - 1.7

B - 1.8

S - 1.5

B - 1.8

S - 1.6

B - 1.6

S - 1.7

B - 1.9

1.

2.

3.

4.

5.

S - 3.2

B - 3.5

S - 3.3

B - 3.3

S - 3.4

B - 3.5

S - 3.2

B - 3.7

S - 3.7

B - 3.8

1.

2.

3.

4.

5.

S - 36.1

B - 36.3

S - 36.1

B - 36.3

S - 36.9

B - 36.9

S - 37

B - 37.1

S - 36.9

B - 38 M

ON

SO

ON

1.

2.

3.

4.

5.

S - 1.5

B - 1.7

S - 1.6

B - 1.9

S - 1.8

B - 1.9

S - 1.8

B - 1.9

S - 1.9

B - 2.0

1.

2.

3.

4.

5.

S - 3.3

B - 3.4

S - 3.3

B - 3.5

S - 3.5

B - 4.0

S - 3.6

B - 4.2

S - 3.9

B - 3.9

1.

2.

3.

4.

5.

S - 37.1

B - 37.2

S - 37.2

B - 37.3

S - 37.3

B - 37.4

S - 37.1

B - 37.8

S - 37.6

B - 37.9

PO

ST

MO

NS

OO

N

S- SURFACE B-BOTTOM

22

2. DISTRIBUTION OF DISSOLVED OXYGEN

More is known about the distribution of oxygen in the sea than other

gases because of the ease with which it can be determined. The observed

vertical and horizontal distributions of the gas in the oceans result from the inter

play between biochemical processes and those by which the gas enters and is

transported in the water. The vertical distribution pattern shows the following

features. A wind mixed surface layer, extending down to the thermocline, has a

uniform oxygen content and is essentially close to the equilibrium with sea

surface. Beneath the surface layer the oxygen content decreases with increase

in depth as a result of oxidation of organic matter. Minima caused by the

biochemical consumption of oxygen is always observed. Beneath the minima

oxygen concentration increases, gradually as a result of circulation of water

from the surface.

The results obtained for dissolved oxygen for the surface and bottom

waters for the three aquatic environments are tabulated below. As a general

observation the dissolved oxygen in the surface waters was greater than the

bottom waters. The D.O. values were highest for the riverine water and the

least for the marine sample. In the estuarine system the values showed

intermediate D.O. content. The max. value observed in the riverine water was

7.7 ppm and the minimum value 7.1 ppm. The corresponding values for

estuarine system were 6.5 ppm and 5.8 ppm, and for the marine system 4.6 ppm

and 4.0 ppm respectively.

There was monthly variation in the D.O. values for all the three water

bodies. The variations in the three water bodies suggest that there is a great

degree of pollution in the in – shore areas resulting in the depletion of oxygen

from the estuary there is a large in-take of oxygen by biological species. Fresh

water system contains the highest amount of dissolved oxygen suggesting less

pollution, low fertilizer utilization, decreased detergent activity, low biological

23

intake etc. The pre-monsoon distribution of oxygen in the sea-water shows no

pronounced fluctuations due to large water mass intermixing, water currents,

balanced equilibrium distribution between sea water and atmosphere, uniform

salinity distribution, low salinity inter action between in-shore and off-shore

waters, wind-water mass- tidal correlations etc.

24

DISTRIBUTION OF DISSOLVED OXYGEN TABLE 2

S-SURFACE B-BOTTOM

RIVERINE ppm ESTUARINE ppm MARINE ppm

1.

2.

3.

4.

5.

S - 7.7

B - 7.5

S - 7.6

B - 7.4

S - 7.5

B - 7.1

S - 7.7

B - 7.5

S - 7.5

B - 7.4

1.

2.

3.

4.

5.

S - 6.4

B - 6.3

S - 6.3

B - 6.2

S - 6.5

B - 6.1

S - 6.4

B - 6.2

S - 6.5

B - 6.1

1.

2.

3.

4.

5.

S - 4.5

B - 4.4

S - 4.4

B - 4.3

S - 4.3

B - 4.2

S - 4.1

B - 4.0

S - 4.5

B - 4.4

PR

EM

ON

SO

ON

1.

2.

3.

4.

5.

S - 7.5

B - 7.4

S - 7.6

B - 7.4

S - 7.7

B - 7.5

S - 7.7

B - 7.4

S - 7.7

B - 7.5

1.

2.

3.

4.

5.

S - 6.4

B - 6.1

S - 6.3

B - 6.2

S - 6.2

B - 6.1

S - 6.1

B - 6

S - 6.0

B - 5.9

1.

2.

3.

4.

5.

S - 4.6

B - 4.5

S - 4.5

B - 4.4

S - 4.4

B - 4.3

S - 4.3

B - 4.2

S - 4.1

B - 4.0 MO

NS

OO

N

1.

2.

3.

4.

5.

S - 7.7

B - 7.6

S - 7.6

B - 7.5

S - 7.5

B - 7.4

S - 7.7

B - 7.2

S - 7.5

B - 7.4

1.

2.

3.

4.

5.

S - 6.5

B - 6.4

S - 6.4

B - 6.3

S - 6.2

B - 6.1

S - 6.0

B - 5.8

S - 5.9

B - 5.8

1.

2.

3.

4.

5.

S - 4.6

B - 4.5

S - 4.5

B - 4.4

S - 4.4

B - 4.3

S - 4.3

B - 4.2

S - 4.6

B - 4.5

PO

ST

MO

NS

OO

N

25

3. DISTRIBUTION OF pH

p

H is an important hydro graphic parameter which exerts a great influence

on the speciation of metals in the aquatic environments. The pH value is strongly

dependent on factors like photosynthesis, respiration, redox potential, carbonate

system etc. The pH influences the activity of organisms, their growth and life

pattern. PH plays a major role in the solubility, stability and absorption of metal

ions in solution. It has been proved that a pH

of 1.5 is absolutely necessary for

the metal ions to remain in solution. There is a considerable change in the metal

species in the pH range of 6.5 – 8

The distribution of pH at the surface and bottom waters for the three

aquatic environments have been studied on a monthly and seasonal basis. The

PH of the bottom water is found to be greater than that of surface waters in

almost all cases. There is no appreciable differecne in pH values between

riverine and estuarine waters. For the marine system , the pH is found to be

slightly greater at all months and at all seasons.

The comparatively higher pH value in marine samples may be attributed

to enhanced photosynthetic activity and hence primary production. The lowered

PH value for the riverine system shows large quantities of freshwater production

and flow. The estuarine water which results from the influx of fresh water from

the river and incursion of saline marine water from the sea shows an inter

mediate PH value, as expected.

The average values of the pH for all months and all seasons for the three

water bodies are given below. On a seasonal basis, there is difference a slight

increase in the PH values values from January to December is from pre monsoon

to post monsoon seasons. But there is remarkable diff in pH values between the

marine sample and the remaining two, for all seasons. A direct correlation exists

between the pH values and the salinity values, the former increases with the

latter.

26

DISTRIBUTION OF PH TABLE 3

S-SURFACE B-BOTTOM

Riverine Estuarine Marine

1. Jan

S - 7.30

B – 7.41

S - 7.44

B - 7.45

S - 8.35

B - 8.36

2. Feb S - 7.31

B - 7.32

S - 8.44

B - 7.46

S - 8.35

B - 8.37

3. Mar S - 7.30

B - 7.31

S - 7.45

B - 7.47

S - 8.35

B - 8.36

4. Apr S - 7.30

B - 7.40

S - 7.48

B - 7.49

S - 8.35

B - 8.36

5. May S - 7.40

B - 7.41

S - 7.50

B - 7.51

S - 8.36

B - 8.40

6. Jun S - 7.32

B - 7.40

S - 7.52

B - 7.53

S - 8.35

B - 8.41

7. Jul S - 7.40

B - 7.41

S - 7.50

B - 7.54

S - 8.35

B - 8.37

8. Aug S - 7.40

B - 7.42

S - 7.60

B - 7.61

S - 8.35

B - 8.40

9. Sep S - 7.50

B - 7.51

S - 7.58

B - 7.59

S - 8.36

B - 8.37

10. Oct S - 7.48

B - 7.49

S - 7.60

B - 7.65

S - 8.35

B - 8.40

11. Nov. S - 7.50

B - 7.52

S - 7.70

B - 7.77

S - 8.39

B - 8.41

12. Dec S - 7.30

B - 7.50

S - 7.76

B - 7.77

S - 8.40

B - 8.41

27

4. DISTRIBUTION OF TEMPERATURE

The distribution of temperature is directly linked to parameters like

density, salinity, pressure and physical processes like exchange of heat with

the atmosphere and other localized factors. The temperature of river water

depends on the sources from which the water originate and the temperature

of the environment of water flow. The temperature of an estuary is governed

by the mixing phenomina between inflowing river water and intruding sea

water. For marine waters pressure, salinity and density are the controlling

factors.

The values of temp is given in the following table on a monthly and

seasonal basis. No significant variation was noticed in temp between surface

and bottom waters. But the bottom water showed a lower temp than surface

waters in all the three environments. The riverine water showed

comparatively greater temp compared to estuarine and marine waters. The

marine system showed lowest and estuarine on intermediate scale. This was

a general observation for all seasons.

For the riverine system the highest temp was 25.50C and the lowest

24.50

C for a premonsoon season in April. For the estuarine system, the

corresponding temperatures were 23.50C and 22.9

0C. For the marine system

the values were 21.50C and 21

0C respectively. The lowest temperatures were

observed in the monsoon season. The value for reverine estuarine and marine

waters were 22.80C and 22.2

0C, 21.5

0C and 21

0C and 20.9

0C and 20

0C

respectively.

The comparatively low depth and shallowness of water in riverine and

estuarine environments may be reason for less pronounced variations in

temperature (Quasim and Sankarnarayanan, 1969). The comparatively lower

28

temperature may be due to heavy rainfall in the monsoon season, as

observed for all the three aquatic systems.

29

DISTRIBUTION OF TEMPERATURE TABLE - 4

S-SURFACE B-BOTTOM

Riverine oC Estuarine

oC Marine

oC

1. Jan

S - 24.5

B – 24.2

S - 23.5

B - 23.1

S - 21.5

B - 21.4

2. Feb S - 23.5

B - 7.32

S - 23.1

B - 7.46

S - 21.4

B - 21.2

3. Mar S - 24.5

B - 24.1

S - 22.8

B - 22.6

S - 21.3

B - 21.1

4. Apr S - 25.5

B - 25.0

S - 23.5

B - 22.9

S - 21.1

B - 21.0

5. May S - 25.4

B - 25.1

S - 23.5

B - 23.2

S - 21.1

B - 21.0

6. Jun S - 22.8

B - 22.7

S - 21.5

B - 21.4

S - 20.9

B - 20.6

7. Jul S - 22.8

B - 22.5

S - 21.4

B - 21.3

S - 20.8

B - 20.7

8. Aug S - 22.7

B - 22.6

S - 21.3

B - 21.0

S - 20.9

B - 20.6

9. Sep S - 22.6

B - 22.2

S - 21.2

B - 21.1

S - 20.8

B - 20.5

10. Oct S - 23.1

B - 23.0

S - 21.1

B - 20.9

S - 20.6

B - 20.2

11. Nov. S - 23.4

B - 23.2

S - 21.1

B - 20.8

S - 20.6

B - 20.2

12. Dec S - 22.5

B - 22.1

S - 21.0

B - 21.0

S - 20.0

B - 20.0

30

DISTRIBUTION OF TRACE METALS

1. DISTRIBUTION OF IRON

The average abundance of Iron in the earth’s crust is 5.6 x 104 µg g

-1

(Ahrens, 1965) in global river water 670 x103 µg L

-1 (Livingstone, 1963), in

ocean water, 3 x103 µg L

-1 with respect to 35

0/00 (Turekian, 1969). Its oceanic

residence time is 140 years (goldbery, 1965), and the principal dissolved species

is Fe(OH)3 (Sillen, 1963). The average concentration of dissolved Iron is global

river water is 0.7 mg L-1

and in sea water , 0.01 mg L-1

.

Most of the Iron in river water is in particulate phase. The dissolved Iron

in rivers is in the colloidal form (Gibbs, 1977; Hart and Davis, 1981).The

comparatively higher concentration of dissolved Iron in rivers and the tendency

to form hydroxide polymers indicate that the removal of Iron from solution is

influenced by changes in pH

and ionic strength encountered by river – borne

dissolved Iron in estuaries (Aston and Chester, 1973). The dissolved Iron

content is high in inflowing river water and its concentration dropped

appreciably on meeting with saline water (Windom et al., 1971). In high saline

water, the variation in dissolved Iron content is negligible. In an estuarine

environment removal of Iron occurs at a high salinity range ( Coonley et al.,

1971)

From a study of radio activity of Fe 59 added to various samples at

different pH

values (Fukai and Huynh – Ngoc, 1968) has shown that pH can

strongly influence dissolved Iron removal by precipitation into particulate form.

During estuarine mixing Iron has been found to be non-conservative . Mayer,

(1982) found that Iron remained fairly conservative with salinity in the marine

estuaries. In low salinity estuarine region (Boyle et al., 1977, Hart and Davies

1981) the dissolved Iron is converted into particulate form. Three Mechanism

have been suggested for this. The Oxidation of Fe (11) to Fe (111) with

precipation of hydrous Ferric Oxide (Windom et al., 1971). Aston and Chester

31

(1973) suggest that scavenging of Iron by natural sediment particles which

could act as negatively charged nuclei for aggregation of Iron colloids. Boyle et

al., (1977) suggest that coagulation of colloidal particles occurs during mixing

process.

32

IRON PROFILE TABLE 5

Premonsoon mgL-1

Monsoon mg L-1

Post monsoon mg L-1

P1

P2

P3

P4

P5

P – 12.05 D - .30

T - 12.35

P - 12.00 D - .50

T - 12.50

P - 11.00 D - 1.49

T 12.49

P - 12.41 D - .11

T - 12.52

P – 12.01 D - .39

T - 12.40

10.89 .63

11.01 .40

11.41

10.96 .39

11.35

10.01 1.39

11.40

10.04 1.30

11.34

8.02 .50

8.52

7.01 .49

7.50

7.00 .37

7.37

7.17 1.22

8.39

7.10 1.15

8.25

L1

L2

L3

L4

L5

P – 12.01 D - .77

T - 12.78

P – 12.56 D - .10

T - 12.66

P - 11.00 D - 1.80

T - 12.80

P - 12.00 D - 1.06

T - 13.06

P - 13.06 D - .50

T - 13.50

11.00 .96

11.96

9.22 1.32

10.54

9.26 1.42

10.68

9.48 1.50

10.98

9.85 .25

10.10

8.06 .90

8.96

8.00 .89

8.89

8.00 1.01

9.01

7.83 1.25

9.08

9.01 .12

9.13

M1

M2

M3

M4

M5

P - 15.17 D - .60

T 15.77

P - 14.01 D - 1.60

T - 15.61

P - 13.05 D - 2.40

T - 15.45

P - 12.48 D - 2.50

T - 14.98

P - 14.06 D - .80

T - 14.86

10.85 .04

10.89

8.01 1.16

9.17

8.40 1.47

9.87

9.50 1.04

10.54

8.01 .14

8.15

6.15 .61

6.76

6.30 .51

6.81

6.53 .75

7.28

7.70 .05

7.28

7.27 .42

7.69

D - Dissolved P - Particulate T - Total

33

In the premonsoon season the concentration of Iron was maximum at Marine

samples, 15.77 mg L-1

(M1) and minimum at Riverine samples, 12.35 mg L-1

(P1). The Riverine region showed a maximum of 12.52 mg L-1

(P4) and a

minimum of 12.35 mg L-1

(P1). The Lake samples recorded a maximum of

13.56 mg L-1

(L5) and a minimum of 12.66 mg L-1

(L2). The maximum and

minimum values for Marine samples were 15.77 mg L-1

(M1) and 14.86 mg L-1

(M5).

In the Monsoon season the maximum was observed at the Lake sample

11.96 mg L-1

(L1) and minimum at the Marine sample 8.15 mgL-1

(M5) for the

riverine environment the maximum and minimum were 11.52 mgL-1

(P1) and

11.35 mgL-1

(P3) for the estuarine region, the corresponding values were 11.96

mgL-1

(L1) and 10.10 mg L-1

(L5) and for the Marine water, the concentrations

were 10.89 mg L-1

and 8.15 mg L-1

(M5) respectively.

For the post monsoon season, the maximum and minimum values were

9.13 mgL-1

(L5) and 6.76 mgL-1

(M1). For river water the maximum and

minimum were 8.52 mgL-1

(P1) and 7.37 mgL-1

(P3), for Lake water, 9.13

mgL-1

(L5) and 8.89mgL-1

(L2) and for Marine water 7.75 mgL-1

(M4) and

6.76mgL-1

(M1), respectively.

From the above observations it can be concluded that the concentration of

Iron in the pre monsoon and monsoon seasons were very high compared to the

post monsoon season and an increasing trend from river to lake to marine in the

pre monsoon period.

34

DISTRIBUTION OF MANGANESE

The average abundance of Manganese in the earth’s crust is 950 x103

µg

g-1

, the average river water concentration is 5 x103µg L

-1 , in ocean water is 2 µg

L-1

. The oceanic residence time is 1400 years and the main species in the

aquatic system are Mn(OH)3 and Mn(OH)4.

The dissolved Manganese concentration in river water is generally higher

than that of sea water. The behavior of dissolved Manganese in estuaries is non-

conservative (Burton and Liss, 1976). The continental margin and the sea floor

are thought to be important sites of mechanisms regulating the concentration of

Manganese (Murray et al. , 1983). The distribution of Manganese in the aquatic

system is controlled by complex interaction between in situ physical and

chemical processes and the bio geochemical cycles (Martin and Knauer, 1982)

Anoxic waters contain relatively high concentration of dissolved Iron and

Manganese (+2 state) essential for the growth of marine plants ( Riley and

Chester, 1971). Manganese is an element very sensitive to redox conditions and

is relatively mobile in natural waters. Manganese exists in several oxidation

states in natural waters, but experiments conducted in various aquatic conditions

show that Mn (IV), the insoluble form is the most stable form in oxygenated

conditions. Where permanently oxygenated conditions are not attained Mn(IV)

could be reduced to Mn(11) form. Hem et,al., (1963) has suggested that the rate

of Mn (11) oxidation is slow, so the metastable Mn(11) ion may persist for

sometime in oxygenated waters.

Several processess may be responsible for the non- conservative

properties of Manganese. (1) The effect of salinity and ionic strength (2) redox

processes leading to a precipitation – dissolution phenomina (3) sorption

phenomina between particles and sediments (4) diffusion from interstitial

waters and(5) Flocculation and coagulation. Flocculation co-agulation

35

phenomina has been investigated by performing laboratory mixing experiments

(Maest et al., 1984) The hydroxides of Manganese act as efficient scavengers of

other metals (Glashy , 1984). When Manganese remobilizations occurs in sub-

toxic sediments , metals associated with the Manganese oxyhydroxide coatings

may also be released. This can result in increased interstitial water

concentrations of these metals ands diffusion into the overlying water column

( Duinker et al., 1982) Non- conservative behavior has also been attributed to

anthropogenic inputs in some, industrialized estuaries (Campbell et al., 1988).

Removal of Manganese may occur by particulate scavenging or co precipitation

with Iron hydroxide in regions of low salinity. Some authors have suggested

that the variability of dissolved metal concentration in rivers is dependent on pH

changes (Shiller and Boyle, 1987).

As a general observation the concentration of Manganese is appreciably

lower in all the three water bodies at all seasons. Compared to the dissolved

phase, the remarkably higher value in the particulate phase may be due to high

degree of adsorption of particulate Manganese from the dissolved phase by

organic matter . The higher concentration of Mn in the riverine water may be

due to high industrial activity centered around the banks of river periyar and

accumulation of Mn bearing rocks at the river origin and its flow to Mn bedded

sand. The high concentration on the particulate may be further supported by the

slower desorption transfer rate and the weaker ion- exchange reactions with the

major cations, like Na+ , Ca

++ and Mg

++ etc. The lower Mn concentration in the

dissolved phase may also be attributed to the high degree of conversion of

dissolved to particulate phase during diatom blooming whereby particulate

organic matter derived from diatom incorporates large quantities of dissolved

Mn(Hunt, 1983). The mobility , transport and partitioning of Manganese in

natural waters is a function of the chemical form of the element, which is

controlled by physico- chemical and biological characteristics of that system.

36

In the pre monsoon the concentration of Mn was max.in the riverine

system (P5) and the minimum in the estuarine region (L3). For the Periyar, the

maximum was observed at (P5) and the minimum at (P1). For the Cochin

estuary the maximum of 4.53 x103 µg L

-1 was observed at (L2) and a minimum

of 3.10 x 103

µg L-1

was observed at (L3). For the Marine water, the maximum

of 4.22 x103

µgL-1

was noticed at (M2) and a minimum of 0.20 x103

µgL-1

was

recorded at (M4).

For the monsoon season the concentration was maximum in the estuarine

water(LI) and the minimum was observed at the Marine system (M5). For the

riverine water, the maximum concentration was observed as 4.25 x103

µg L-1

(P2) and a minimum was observed as 0.08 x103 µgL

-1(P5). For the estuary a

maximum of 4.96 x103

µgL-1

was seen at (L1) and a minimum of 1.24 x103

µgL-1

at (L4). For the Marine waters, the maximum and minimum values were

1.08 x103 µgL

-1(M4) and 0.04 x10

3 µgL

-1 (M3), respectively.

For the Post Monsoon season the maximum and minimum concentration

were 3.75 x103

µgL-1

(P5) and 2.32 x103

µgL-1

(P4) for Riverine water body

3.73 x103

µgL-1

(L4) and 3.31 x103

µgL-1

(L5), for the estuarine aquatic system

and 3.55 x103 µgL

-1 (M5) and 1.33 x10

3µgL

-1 (M1), respectively)

37

MANGANESE PROFILE TABLE - 6

PREMONSOON mgL-1

MONSOON mgL-1

POSTMONSOON mgL-

1

RIV

ER

INE

Total

D ----- .12 2.16

P ------ 2.04

D------ .54

P------ 2.00 2.54

D------ .45

P------ 2.40 4.85

D----- .51

T------ 3.45 3.96

D------ .20

T------- 4.05 4.25

Total

1.18

3.00 4.18

1.25

3.00 4.25

1.19

3.01 4.20

.56

1.40 1.96

.01

.07 0.08

Total

.75

2.44 3.21

.56

2.40 2.96

.38

2.00 2.38

.32

2.00 2.32

.25

3.50 3.75

.ES

TU

AR

INE

D----- .16

P----- 2.99 3.15

D----- .54

P----- 3.99 4.53

D---- .10

P----- 3.00 3.10

D---- .27

P----- 3.75 4.02

D---- .27

P----- 4.05 4.29

1.95

3.01 4.96

1.29

3.60 4.89

1.02

3.07 4.09

.24

1.00 1.24

.22

3.66 3.88

.31

3.01 3.32

.49

3.10 3.59

.47

3.00 3.47

.72

3.01 3.73

.32

2.89 3.31

MA

RIN

E

D----- .27

P----- .75 1.02

D---- .22

P----- 4.00 4.22

D---- .47

P----- 2.40 2.87

D---- .04

P----- .16 0.20

D---- .15

P----- .65 0.80

.27

.75 1.02

.26

.75 1.01

.24

.80 1.04

.02

.07 0.09

.02

.06 0.08

.32

1.01 1.33

.48

3.01 3.49

.37

3.00 3.37

.97

2.01 2.98

.54

3.01 3.55

38

3. DISTRIBUTION OF COPPER

Copper is relatively abundant in the earth’s crust (24 to 55 x103

µg -1

Alloway,

1990) and moderately soluble in water. The world average concentration of Cu

in the aquatic environment is reported to be 3 µgL-1

in the range 0.2 to 30 µgL-1

in uncontaminated fresh water systems. The distribution in surface sea water

ranges from 0.03 to 0.23 x103

µgL-1

, and in deep sea water from 0.2 to 0.69

x103µgL

-1 (Bowen, 1985). The acceptable Cu levels in drinking water in India is

0.05 mg L-1

( IS 10500, 1983).

The activities by which Cu enters the soil, sediment and water are

processes of smelting and mining, industrial effluent discharge, urban run off

and application of fertilizers, fungicides etc. The forms taken by this metal in

natural waters (Ionic, complexed or precipitated) and hence its bio availability

depends on environmental factors such as PH, Eh, soil and sediment type, water

hardness, organic content etc and in estuaries especially on salinity, fresh water

discharge, mean residence time and the suspended soil load . Natural

transformation takes place during chemical complexation, precipitation and

adsorption by which Cu is removed from water into sediments (Salomons et al,

1984) Most cupric salts readily dissolve in water to give the free Cu(11) ion in

the hydrated form [Cu(H20)6] 2+

. Cu (11) ion is a strong complexing agent and

the free cationic form has a greater tendency towards hydrolysis. The Cu(11)

ion forms strong complexes with the electron donor groups in organic

compounds (O,N and S). In general, the stability of chelates, such as Cu-humic

complexes is greater than those of closely related non-chelate complexes. In the

Cochin estuary, higher percentage of Cu has been reported (Paul and Pillai,

1984). It has been reported that particulate associated fractions decreased

towards the saline region while dissolved fractions recorded an increase. It has

39

also been reported that an extensive organic association of Cu was observed

(Shibu et al., 1990).

While conducting a study on the behavior of dissolved Cu in Rushikulya

estuary, Dash and Sahu (1999) have concluded that removal of dissolved Cu is

mainly due to co-precipitation with humic suspended matter. The depletion of

dissolved Cu at the surface and enrichment in the bottom layers have been

attributed to remobilization from shelf sediments and subsequent diffusion into

overlying waters and release from decomposed organisms. (Murty and Sathya

Narayana, 1999). Cu (11) is always found to be strongly complexed in estuarine

and marine waters decreasing their bioavailability and possible toxicity

(Voelkar et al., 2001). The effect of biological activity changes on kinetics and

equilibrium characteristics of the reaction of Cu with macro algae, Porphyra

SPP and enteromorpha SPP has been worked out (Vasconcelos and leal, 2001.)

The concentration level of Cu in Estuarine waters showed a maximum of

2.70 x103 µgL

-1 (L5) and a minimum of 0.17 x10

3 µgL

-1 (M4) at the marine

environment. For the pre monsoon season , for the Periyar waters, a maximum

of .712 x103

µgL-1

(P5) and a minimum of .336 x103

µgL-1

(P4) was observed.

For the Lake waters a maximum of 2.70 x 103 µgL

-1 (L5) and a minimum of

.431 x103

µgL-1

(L1) was noticed. For the marine waters a maximum of 2.69

x103 µgL

-1 (M5) and a minimum of 1.30 x10

3 µgL

-1 (M3) was obtained.

For the Monsoon season, in the Riverine region a maximum

concentration level of 2.56 x103

µgL-1

(P1) and a minimum value of 2.02 x103

µgL-1

(P2), was observed. For the estuarine region, a maximum value of 2.26

x103 µgL

-1 (L5) and a minimum value of 1.61 x10

3µgL

-1 (L4) were obtained.

For the Marine region, a maximum of 0.98 x 103 µgL

-1 (M5) and a minimum of

0.17 x103 µgL

-1 (M4) were obtained.

40

The post Monsoon season showed , in the Periyar environment maximum

concentration level of 2.69 x103µgL

-1 (P4) and a minimum level of 0.86 x10

3

µgL-1

(P5) were noticed. For the Cochin estuary, a maximum value of 1.99 x103

µgL-1

(L2) and a minimum value of .08 x103µgL

-1 (L5) were observed. For the

sea eater, a maximum concentration of 2.35 x 103 µgL

-1 (M2) and a minimum

concentration of 0.33 x103 µgL

-1 (M5) were shown experimentally.

For all seasons, in all the three aquatic environments, as expected, the

particulate content is appreciably greater than the dissolved material. The large

accumulation of particulate Copper than dissolved may be attributed to the co-

precipitation with suspended humic matter. In the riverine water, the particulate

content had decreased which might be due to the passage of more particulate

into dissolved phase by the hydrolysis of readily available Cu salts. The Cu

content in Cochin estuary is comparatively higher than riverine and Marine

regions due to mobilization from particles and diffusion from sediments. The

particulate Cu increase may result from the uptake by plankton. The Cu

distribution co-efficient in the marine waters (Concentration of

particulate/concentration of dissolved KD) increases appreciably when

compared to the other water bodies. The partitioning of Cu between the

particulate and filter-passing dissolved phase is strongly influenced by organic

mediation . The poor representation of Cu in the marine system is attributed to

strong sedimentation of Cu metal complexed with organic ligands and high

salinity conditions. Cu speciation appeared to be governed by two classes of

selective organic ligands, where the legands refer to colloidal organic matter. In

all study areas colloidal Cu was significantly related to organic carbon

concentration. The interaction of the metal with macromolecular organic matter

is determined by affinity to specific functional groups.

41

COPPER PROFILE TABLE - 7

PREMONSOON mgL-1

MONSOON mgL-1

POSTMONSOON mgL-1

RIV

ER

INE

P1

P2

P3

P4

P5

Total

D -----.156

P ------.300 .456

D------ .210

P------ .300 .510

D------ .142

P------ .207 .349

D----- .104

T------ .232 .336

D------ .212

T------- .500 .712

Total

.32

2.24 2.56

.27

1.75 2.02

.28

1.75 2.03

.47

2.00 2.47

.72

2.20 2.52

Total

.59

2.00 2.59

.32

1.03 1.35

.46

1.30 1.76

.69

2.00 2.69

.44

1.42 0.86

.ES

TU

AR

INE

L1

L2

L3

L4

L5

D----- .200

P----- .231 .431

D----- .25

P----- 1.25 1.50

D---- .30

P----- 1.45 1.75

D---- .37

P----- 2.02 2.39

D---- .35

P----- 2.35 2.70

.35

1.40 1.75

.46

1.40 1.86

.50

1.75 2.25

.31

1.30 1.61

.46

1.80 2.26

.02

.07 .09

.32

1.67 1.99

.34

1.64 1.98

.35

1.42 1.77

.02

.06 .08

MA

RIN

E

M1

M2

M3

M4

M5

D----- .04

P----- .14 0.18

D---- .31

P----- 2.31 2.62

D---- .41

P----- 2.18 2.59

D---- .03

P----- .14 0.17

D---- .22

P----- 2.47 2.69

.04

.14 0.18

.05

.95 0.20

.22

.66 0.88

.04

.13 0.17

.08

.90 0.98

.16

.40 0.56

.35

2.00 2.35

.11

.60 0.71

.32

1.99 2.31

.11

.22 0.33

42

4. DISTRIBUTION OF ZINC

The average range of concentration of Zn in the earth’s crust is 65-80

x103

µgg-1

The average Zn level in sea water varies between 0.1 x103 µgL

-1 at

the surface and 0.62 x10

3 µgL

-1 in the deep waters (Bruland et al., 1983) in the

fresh water. The average concentration has been found to be 10 x103 µgL

-1

(Wedepohl , 1972). Zn is a component of many enzymes. It is involved in the

synthesis of RNA and DNA and cuts to diminish the biological toxicities of

other metals such as Cu and Cd. Adsorption into organic and inorganic particles

is the dominating process controlling the equilibrium concentration of Zn in sea

water (Turekian, 1977). A significant amount of Zn in sea water is organically

complexed. ( Van den Berg et al., 1987)

Conducting investigations on the influence of trace metal Zn on various

aquatic organisms it was proved that the metal in excess was highly toxic and

fatal to them (Sadiq, 1992). It was demonstrated in another experiment that

trace metal Zn was concentrated at a range of (12-650 x103

µgL-1

) in certain

fishes and invertebrates which was a pointer to the mass mortality of the

species (Ambrose et al., 2001) In another experiment the use of plankton as bio

monitors of metal pollution by Zn has been investigated in several marine and

estuarine systems (Senthilnathan and Balasubramaniam, 1999)

Zn is classified as a boarder line metal, meaning that it forms bonds with

oxygen as well as Nitrogen and Sulphur donor atoms under aerobic conditions.

Zn2+

is the predominant species at acidic pH

, but is replaced by Zn (OH)2 at pH

8-11 and Zn(OH)3/Zn(OH)42-

at pH> 11. Samarindou and Fytianos (1987)

working on two rivers in Northern Greece, noted that Zn is partitioned primarily

into the sulphide and Fe-Mn hydrous oxide fractions of the sediments. By

studying the vertical distribution pattern of Zn in coastal waters of

Visakhapatanam, Murty and Satyanarayana (1999) have shown that the surface

43

depletion and bottom enrichment were due to its uptake by organisms at surface

and subsequent regeneration of it from sinking biological matter at bottom

waters. The biochemistry of Zn reveals that it may act synergistically and

antagonistically to influence phytoplankton growth (Donat and Bruland, 1995)

The chemical speciation studies of Zn in surface waters of Western Black sea

showed that the Zn – binding ligands gave a good correlation with suspended

particulate matter indicating that the ligands were produced in situ by the

bacterial break down of particulate organic matter. (Francois et, al., 2001) In the

Galweston Bay, Texas, Zn was found to complex with thiols and sulphides at

both neutral and basic PH (Tang and Santschi, 2000) .

The distribution of Zn showed a maximum value of 4.27 mgL-1

(P3) at

the riverine region in the pre monsoon season and a minimum value of 2.03

mgL-1

(L1) at the lake water in the post monsoon season. As expected, the

partitioning of Zn between dissolved and particulate species as given by

partitioning ratio, KD showed greater accumulation in the particulate samples.

However, the KD values showed fluctuations in the three seasons. For the

riverine water, a maximum of 4.27mg L-1

(P1) was observed in the pre

monsoon season. For the estuarine water, a maximum of 4.07 mgL-1

(P3) and a

minimum value of 1.777 mgL-1

(L4) was noticed. For the Marine system a

maximum concentration of 3.66 mg L-1

(M3) and a minimum concentration of

.420 mgL-1

(M1) was observed.

In the monsoon season, for the riverine body a maximum value of 1.016

x103 µgL

-1 – mg L

-1(P5) and a minimum value of .104 x10

3µgL

-1 (P1) was

noticed. For the Lake sample, a maximum of .15 x103 µgL

-1 - (L4) and a

minimum of .04 x103 µgL

-1 -)L1) was observed. For the marine sample ,a

maximum concentration of .41 x103 µgL

-1 - (M1) and a minimum concentration

of .02 x103 µgL

-1 -

(M4) was detected.

44

For the post monsoon season a maximum accumulation of .88 x103

µgL-1

(P1) and a minimum of .084 x103

µgL-1

(P5), a maximum of .12 x103

µgL-1

(L1) , a minimum of .02 x103

µgL-1

-, a maximum of .21 x103

µgL-1

(M1) and a

minimum of .047 x103

µgL-1

(M3) were detected for the pre monsoon,

Monsoon and post monsoon seasons respectively.

The high concentration of Zn in the Periyar water during premonsoon

season is attributed to the enhanced industrial activities and the effluent

discharge into the river. High Zn concentration in water could have resulted due

to the release of this metal from the sediment and abundant organic matter

derived from the seaweeds and freshwater inputs along with various drainages

at the bar mouth of Cochin estuary . Further, during the pre monsoon season

when Zn concentration was high, phosphate and nitrate concentrations was also

high. This is evidenced by a statistical analysis which revealed a positive

significant relationship between Zn and Phosphate. At the post monsoon season

Zn concentration was low at all stations. This would have resulted due to the

utilization and uptake of Zn along with other nutrients by the biota including

phytoplankton. Evidently the phytoplankton density was high (75,650 cell L-1

)

during the summer season at the Cochin estuary. Zn could get strongly depleted

from the surface water as it has a nutrient type distribution in seawater. The

Marine water contained lesser quantities of Zn at all stations at all seasons

which is explained by its strong co-rrelation with the physicochemical

parameter like salinity, alkalinity, PH and the dissolved oxygen content. The

high concentration of Zn in lake water throws light into extended pollution

index presented by this metal.

45

ZINC PROFILE TABLE - 8

PREMONSOON mgL-1

MONSOON mgL-1

POSTMONSOON mgL-1

RIV

ER

INE

P1

P2

P3

P4

P4

Total

D -----.15

P ------.35 0.50

D------ .54

P------ 1.04 1.58

D------ .27

P------ 4.00 4.27

D----- 1.10

T------ 3.00 4.10

D------ 1.17

T------- 3.02 4.19

Total

.04

.064 .104

.03

.081 .111

.04

.24 .28

.27

.71 .98

.25

.76 1.01

Total

.23

.65 .88

.02

.05 .07

.03

.64 .77

.11

.64 .75

.02

.06 .08

.ES

TU

AR

INE

L1

L2

L3

L4

L5

D----- 1.14

P----- 2.00 3.14

D----- 1.01

P----- 3.00 4.01

D---- .34

P----- 1.64 1.98

D---- .32

P----- 1.45 1.77

D---- .33

P----- 2.55 2.88

.01

.03 .04

.02

.03 .05

.03

.09 .12

.04

.11 .15

.02

.07 .09

.01

.01 .02

.04

.08 .12

.03

.09 .12

.02

.07 .09

.02

.06 .08

MA

RIN

E

M1

M2

M3

M4

M5

D----- .12

P----- .30 0.420

D---- .119

P----- .400 .519

D---- .34

P----- 3.32 3.66

D---- .45

P----- 2 .14 2.59

D---- 1.02

P----- 2.00 3.02

.11

.30 .41

.11

.28 .39

.02

.07 0.09

.01

.01 0.02

.04

.24 0.28

.04

.17 .21

.01

.03 .04

.04

.07 .11

.04

.15 .19

.02

.07 .09

46

5. DISTRIBUTION OF CHROMIUM

Chromium occurs in the earth’s crust at an average concentration of 100

mgkg-1.

The average concentration in river water is I x103µg L

-1 ( Turekian,

1969), and in ocean water, 0.6 x103 µgL

-1 . Its residence time is 350 years.

In rock minerals, the principal oxidation state is Cr+3

and Cr+6

(Elderfield,

1970). The probable main dissolved species of Cr in aquatic system is hydroxy

complexes. Cr has a nutrient type distribution as a result of its in situ

production by biological reduction process. In oxygenated waters the dominant

redox species is a tetrahedral oxy – anion (CrO42-1

), which has a low affinity for

deprotonated oxide surfaces that accounts for its nearly conservative

distribution in estuarine waters( Craston and Murray, 1980). In fresh water the

existing forms are Cr (OH)2+

, Cr(OH)2+ and Cr(OH)4

- (Riley and Chester 1983).

Cr (VI) is highly mobile in aquatic systems, whereas Cr(III) is quickly

immobilized in the sediments (Moore, 1991).

The reduction of Cr(VI) to Cr(III) can occur under both sub-toxic and

anoxic conditions (Emerson et al ., 1979). In situ reduction by photolytically

generated Fe(II) has been observed in estuarine waters (Kieber and Helz,

1992).The oxidation of Cr(III) to Cr(IV) is inhibited by the ligand field.

stabilization energy of octahedral Cr(III) (Burns, 1993).

The toxicity of Cr to marine organisms depends on the metal speciation

and environmental factors such as temperature, salinity, pH, Eh, dissolved

oxygen , light intensity etc. The Cr(III) is found to be more toxic to marine

organisms (Riley, 1989.)

The mechanism of Cr enrichment in biota of the San Fransisco Bay

estuary has been worked out by (Decho and Luoma, 1994) and showed that a

spatial gradient was found to exist in Cr concentrations of bivalves. The spatial

distributioin of Cr redox species in the estuarine water is controlled by the

super position of advective mixing in situ reduction, resuspension, and

47

anthropogenic inputs, as revealed by studies in the San Fransisco Bay estuary

(Abu – Saba et al., 1995). Studies of dissolved Cr in estuarine systems suggest

that reductive scavenging may take place in the low salinity regions ( Craston

and Murray, 1980). It has been proposed that if Cr (III) is bound by dissolved or

colloidal organic matter, scavenging of Cr (III) may be inhibited (Mayer et al.,

1982).

Although Cr+6

is highly mobile in aquatic system, Cr+3

is quickly

immobilized in the sediments it has been reported that the adsorption of Cr+3

was linearly dependent on soluble metal concentrations and that subsequent

description over a period of at least 24 days. Samanidou et al., (1987) studied

the partitioning of Cr into selective chemical fractions in the sediments of rivers

in northern Greece and found that the dominant species were associated with

organic sulphides and Fe-Mn hydrous oxides studies. Studies made on the

distribution of Cr (VI) in the Arctic and Atlantic oceans, revealed that it was

depleted in surface waters and poor correlation existed between Cr(VI)

concentration and nutrients and it exhibited intermediate behaviour between the

“accumulated ” and “ recycled” types (Turner et al., 2000). The depletion of Cr

(VI) along with a concurrent increase in the Cr(III) in a shallow region of San

Fransisco Bay was attributed to the in situ reduction (Abu – Saba et al., 1995).

The examination of Cr content in soil with a view to differentiating between

natural and anthropogenic sources of Cr showed that natural Cr is particularly

linked to pyroxenes whereas anthropogenic Cr is adsorbed by vermiculites on

their interfoliary- sites which possess high capacity of cation exchange .

48

CHROMIUM PROFILE TABLE - 9

PREMONSOON mgL-1

MONSOON mgL-1

POSTMONSOON mgL-1

RIV

ER

INE

P1

P2

P3

P4

P5

Total

D ----.0.28 1.01

P -----0.73

D------1.50 4.61

P------ 3.11

D----- 1.1 4.5

P------ 3.4

D----- 1.08 4.05

P------ 2.97

D------0.75 2.01

P------ 1.26

Total 0.84 2.21

1.37

0.99 2.20

1.21

0.59 1.79

1.20

0.44 1.80

1.36

0.98 2.24

1.26

Total 0.76 2.32

1.56

0.86 2.87

2.01

1.56 4.02

2.76

1.23 4.24

3.01

0.67 1.90

1.23

.ES

TU

AR

INE

L1

L2

L3

L4

L5

D----- 1.2 4.7

P----- 3.5

D----- 2.09 4.10

P----- 6.01

D---- 1.44 4.20

P----- 2.76

D---- 1.50 4.28

P----- 2.78

D---- 0.88 2.10

P----- 1.22

1.44 4.00

2.56

0.84 2.46

1.62

1.01 3.99

2.98 1

1.04 4.04

3.00

0.59 2.11

1.52

0.67 1.88

1.21

0.75 4.32

3.57

1.23 3.72

2.49

1.47 4.03

2.56

1.33 4.42

3.09

MA

RIN

E

M1

M2

M3

M4

M5

D----- 0.25 0.96

P----- 0.71

D---- 0.04 1.06

P----- 1.02

D---- 0.06 0.24

P----- 0.18

D---- 0.04 0.16

P----- 0.12

D---- 0.11 1.30

P----- 1.19

0.05 1.10

1.05

0.04 1.47

1.43

0.03 1.59

1.56

0.07 2.05

1.98

0.09 1.30

1.21

0.11 0.47

0.36

0.67 1.93

1.26 2.35

1.37

0.86 2.34

1.48

0.76 1.99

1.23

49

The distribution of Chromium showed that the highest concentration was

in the Estuarine region in the pre monsoon season with a value of 4.70 x103

µgL-1

(L1) and the lowest concentration in the marine region in the post

monsoon season with a value of 0.47 x103

µgL-1

(M1). Among the three

aquatiic bodies, the marine system showed a lower concentration level and the

estuarine body showed the highest concentration levels. On a seasonal basis the

pre monsoon detected the highest concentration and the monsoon season

detected the lowest concentration.

For the Riverine water a highest concentration value of 4.50 x103µgL

-1

(P3) and a lowest concentration value of 1.01 x103 µgL

-1 (P1) was noticed in

the pre monsoon season. For the Monsoon, season the highest and lowest value

were 2.24 x103

µgL-1

(P5) and 1.80 x103µgL

-1 (P3) and for the post monsoon

season, the values were 4.24 x103 µgL

-1 (P4) and 1.90 x10

3 µgL

-1 (P5)

respectively.

For the estuarine environment in the Pre monsoon season, a highest

value of 4.70 x103 µgL

-1 (L1) and a lowest value of 2.10 x10

3 µgL

-1 (L5) were

observed. For the Monsoon and post monsoon season, the corresponding values

were 4.04 x103 µgL

-1 (L4), 2.11 x10

3 µgL

-1 (L5) and 4.32 x10

3µgL

-1 (L2) and

1.88 x103µgL

-1 (L1), respectively.

For the Marine body, for the premonsoon, Monsoon. And Postmonsoon

seasons, the highest and lowest combinations were 1.30 x103 µgL

- (M5), 0.16

x103µgL

-1 (M4) and 2.05 x10

3µgL

-1 (M4) , 1.1 x10

3µgL

-1 (M1) and 2.35 x10

3

µgL-1

(M5) 0.47 x103 µgL

-1 (M1) respectively.

The particulate phase contained relatively high concentration of

Chromium compared to the dissolved phase in all the three environments at all

seasons. This may be attributed to the high degree of adsorption of organic

carbon content and sediment re suspension. The comparatively low value in the

50

riverine water might be due to high desorption activities due to heavy monsoon

rainfall, high water flow and low organic carbon content. The lowest value

observed in the sea water is due to its correlation with the physicochemical

parameters like salinity, alkalinity, pH, dissolved oxygen and suspended

particulate matter. In the marine waters, the vertical profiles show modest

depletion of Chromium (VI) in surface waters, but poor overall correlation

between Cr (VI) and nutrient profiles given that Cr(VI) is the dominant

oxidation state of Chromium in open – ocean waters. These data are combined

with literature data to realiaze the distribution of Cr on oceanic waters. Even

though Cr is in corporated into plankton it did not have any biochemical

function. A substantial depletion in the surface mixed layer may be due to

biological uptake or by the redox chemistry due to the formation of Cr (III) in

sea water, the distribution of Cr in the cochin estuary where the relatively high

concentration is observed due to localized inputs , in situ reduction, sediment re

suspension and re mineralization . The Cr(III) scavenging residence time

suggests that complexation by colloidal and organic matter plays a key role.

51

6. DISTRIBUTION OF LEAD

Lead is the 36th abundant element in the earth’s crust with an average

concentration of 3 x103 µg L

-1 (Ahrens, 1965). It occurs in the river water with

an average concentration of 3 x103 µgL

-1 (Living stone, 1963) and in sea water

at 3 x 10-2

µgL-1

(Turekian, 1969) . Its oceanic residence time is 2 x 103 years (

Goldberg, 1965). The important dissolved species of Pb are Pb+2

, Pb(OH)+ and

PbCl+ (sillen, 1963).

The total amount of Pb discharged to fresh waters from anthropogenic

sources amounts to (97-180) x 10 metric tons per year (Nriagu and Pacyna,

1988). In fresh water Pb forms a number of complexes of low stability with

many of the major anions, including hydroxides, Carbonates, Sulphides and

Sulphates . Pb also partitions favorably with humic acid, Fulvic acids forming

moderately strong chelates. Approximately 70% of Pb in river is in suspension

and 25% in solution. But in salt water the corresponding ratio is approximately

50:50.

Numerous organic complexes are found in the atmosphere and rain water

due to the use of Pb in fuels . (Allen et al., 1988) recorded the presence of Me4

Pb, Me3 Et Pb, Me3Pb+ and Et4 Pb in the atmosphere and rain water. Sorption

to sediments play a key role in the fate of Pb complexes. Under laboratory

conditions, most Pb compounds exist in solid phase above pH7. In a study

conducted in one Greek river it was established that over 50% of the sediment

bound Pb was associated with complexation with sulphides and Fe- Mn hydrous

oxides (Mc Kee et al., 1989). Total lead residues are generally low in fresh

water fish. The maximum allowable concentration in fish tissue being 2 mg

Kg-1

(Mason, 1987) Analysis of Pb residues in two species from River Periyar

revealed that they contained an average value of 2mg Kg-1

near waste out falls

from ore – processing plants and were lower by approximately 50% in down

52

stream areas (barker et al., 1984). Inorganic Pb is moderately toxic to aquatic

plants and invertebrates in both marine and fresh water systems, but its toxicity

is less than that of Cd, Cu and Hg. Studies made in the Cochin estuary on the

speciation of Pb revealed that about 75% of the total Pb existed in the dissolved

form (Shibu, 1992). An analysis made on the distribution of Pb between the

‘plant available Pb’ and the total Pb ratio in the soils and stream sediments of an

urban catchment in Tyneside, U.K. revealed that, the plant available Pb is

approximately lower than the total Pb . In a study conducted for the Pb

concentrations in the dissolved and particulate phases of North Australian

coastal and estuarine water showed that strong correlations existed for Pb versus

suspended particulate matter (SPM) for the unfiltered seawater. The Pb isotope

ratios Pb 208

/Pb 206

and pb207

/ Pb206

of filtered (0.45 µ m) seawater samples

generally were more variable at a given location than the ratios of the unfiltered

samples. The partitioning of Pb between the particulate and dissolved phases

suggested that SPM represent a significant source of metal for sedimentating

organisms. ( Turner et al., 1992).

The distribution pattern of Pb showed the highest value of 5.03 x103µgL

-1

(L1) in the estuarine region in the pre monsoon season and the lowest value of

0.09 x103µgL

-1 (M1) in the marine region in the post monsoon season. The

distribution co-efficient of the metal between the particulate and dissolved

phases showed fluctuations and no theoretical formulations could be found.

However the ratio showed a narrow range of less than 10. The estuarine

concentration showed remarkably higher values in the pre monsoon season. The

Marine representation of Pb was exactly similar to other metals studied whereby

the concentration levels were comparatively poor. The monsoon season showed

the lowest values of concentrations when compared with the Pre Monsoon and

post monsoon season.

For the riverine water the highest and lowest values for the pre

monsoon, monsoon and post monsoon seasons were- 2.33 x103µgL

-1 (P5) .925

53

x103 µgL

-1 (P1) ---- 2.30 x10

3 µgL

-1 (P4), 0.10 x10

3µgL

-1 (P1)---- 1.65 x10

3

µgL-1

(P2), 0.30 x103 µgL

-1 (P4) respectively.

For the estuarine environment the highest and lowest values observed for

the pre monsoon , Monsoon and post monsoon season were 2.10 x103µgL

-1

(L1), 1.98 X 103µgL

-1 (L3)---- 1.88 x10

3µgL

-1 (L1) and 0.50 x 10

3 µgL

-1

(L2), 0.31 x103 µgL

-1 (L4) and 0.25 (L4) respectively.

For the marine body, the highest and lowest concentration values noticed for

the pre- monsoon, Monsoon and Post monsoon season were 1.98 x103µgL

-1

(M5), 0.88 µgL-1

(M2) and 2.2 x103 µgL

-1 (M5), .8 x 10

3 µgL

-1

(M3)--- 1.58

x103 µgL

-1 0.09 x10

3 µgL

-1 (M4) respectively.

The heavy accumulation in the particulate phase with simultaneous

depletion from dissolved might be due to the high degree of adsorption, heavy

accumulation of suspended particulate matter, high organic carbon content and

large extent of biological uptakes. The salinity element correlation was less

appreciable as indicated by the low Pb content in highly saline marine waters.

The hydrographical parameters like alkalinity, dissolved oxygen, pH , Eh and

conductivity values coupled with large sedimental re suspension and inter stitial

waters accounts for the relatively tremendous concentration jump in the

estuarine waters in the pre monsoon season. The industrial effluents from the

production activities on the banks of River Periyar and the agricultural

activities contribute to the remarkably higher concentration levels in the pre

monsoon season. Variations in the Pb isotope ratios of unfiltered samples

dominated by Pb in suspended particulate matter in the estuarine and marine

samples were found to reflect different compositions in the geological units in

their catchments. River and anthropogenic inputs, and biological and geo

chemical cycling may influence the concentration of Pb in estuarine and

coastal sea water to a much greater extent than that occurring in open-ocean

water. The heavy accumulation of Pb in the lake samples show that the aquatic

54

environment is immensely polluted by Pb salts which is harmful to the aquatic

organisms and adversely affect primary production.

55

LEAD PROFILE TABLE - 10

PREMONSOON mgL-1

MONSOON mgL-1

POSTMONSOON mgL-1

RIV

ER

INE

P1

P2

P3

P4

P5

Total

D -----.100

P ------.825 .925

D------ .56

P------ 1.00 1.56

D------ .50

P------ 1.50 2.00

D----- 1.1

P------ 1 2.10

D------ 1.00

P------- 1.33 2.33

Total

D ----- .02

P ----- .08 .10

D------ .04

P------ .16 .20

D------ .15

P------ .80 .95

D----- .30

P------ 2.00 2.30

D------ .48

P------- 1.50 1.98

Total

D ----- .32

P ------ 1.24 1.56

D------ .33

P------ 1.32 1.65

D------ .18

P------ .32 0.50

D----- .14

P------ .20 0.34

D------ .11

P------- 1.00 1.11

.ES

TU

AR

INE

L1

L2

L3

L4

L5

D----- .70

P----- 1.40 2.10

D----- .10

P----- .40 0.50

D---- .34

P----- .39 0.50

D---- .28

P----- .70 .98

D---- .17

P----- .70 .87

D----- .25

P----- 1.00 1.25

D----- .34

P----- 1.02 1.36

D---- .48

P----- 1.50 1.98

D---- .04

P----- .27 0.31

D---- .19

P----- .40 0.59

D----- .62

P----- 1.26 1.88

D----- .47

P----- 1.40 1.87

D---- .32

P----- .66 0.98

D---- .04

P----- .21 0.25

D---- .05

P----- .51 0.56

MA

RIN

E

M

1

M

2

M

3

M

4

M

5

D---- 0.18

P---- 0.80 0.98

D---- .17

P----- .81 0.88

D---- .11

P----- 1.00 1.11

D---- .36

P----- 1.40 1.76

D---- .58

P----- 1.40 1.98

D---- .33

P---- 1.04 1.37

D---- .38

P----- .50 .88

D---- .17

P----- .70 .87

D---- .52

P----- 1.06 1.58

D---- .04

P----- .18 2.2

D---- .03

P---- 0.6 0.09

D---- .21

P----- 1.04 1.25

D---- .33

P----- 1.07 1.37

D---- .02

P----- .07 .09

D---- .48

P----- 1.10 1.58

56

7. DISTRIBUTION OF MERCURY

The average abundance of Mercury in the earth’s crust is 0.08 g-1

(Ahrens, 1965). The average concentration of Hg in river water is 0.07 x103 µg

L-1

(Livingstone, 1963). In the sea water its average concentration is found to

be 5 x 10-2

µgL-1

in a salinity range of 350

0/00. (Turekian, 1969) Its oceanic

residence time is 4.2 x 104 years (Goldberg, 1965) and the principal probable

dissolved species in the sea water is HgCl -2

(Sillen, 1963).

Mercury in different chemical forms enters the aquatic environment from

a variety of sources. Industrial effluents comprising Chlor – alkali, pigments,

waste from electrical installations, catalytic contribute to a great extent. Other

predominant sources are wastes of agricultural origin, fallout from the

atmosphere, dumped materials etc. The distribution and evolution of mercury

in different kinds of water columns depends on the hydrodynamic conditions

and the physico – chemical conditions of the region, the assimilation of

Mercury by living organisms including transfer through food chains, its

interactions with other constituents of the aquatic body , the various physical

and chemical changes taking place in sediments etc.

Considering the thermodynamic stability and the standard free energy of

formation, the forms of inorganic mercury compound available in water shows

the occurrence of Mercury (I) carbonate, but Mercury (II) Carbonate is not

available. Among the most important organic form of Mercury is dimethyl

Mercury in marine and estuarine waters. The electrochemical and chemical

equilibrium curves under different conditions of redox potential and PH values

were studied under conditions of normal temperature and pressure (Muresan, B

et al., 2006) . The Eh –pH diagrams for the four element system (Hg –Cl – S –

H20 was investigated and the stability of mercury (1) Carbonate and Dimethyl

57

and Mercury was established thermodynamically. (Morel FMM et al., 1998).

At the PH values likely to occur in surface sea water and brackish water, liquid

metallic mercury is theoretically the stable solid compound at high Eh values,

where Mercury (1) Chloride ( calomel) is more stable. In mildly reducing

conditions usually in the interstitial water of the sediments HgS ( Cinnabar) is

predominantly the solid species. In well aerated sea water the anionic complex

HgCl -3 is the most stable compound over a wide range of P

H values. At high P

H

values in braekish water Hg (OH)2 is predominant (Laperche , et al., (2007) . In

reducing conditions, which may occur in sediments, or in an anaerobic water,

HgS2 is the most stable dissolved species for a PH value greater than 5 and Hg

(SH)2 at lower pH

values. Methyl Mercury is a very important form of Mercury

in fish and in sediments. Most Mercury species are much more soluble in

organic solvents than in water (King J.K et al., 2012, ), The spatial distribution

of dissolved and particulate forms of mercury collected from Plankton

samples have shown that they are in a 1:1 ratio approximately at the

premonsoon season (Flemming B W, 2000) For Methyl Mercury, the total Hg

ratio varies between 32 and 94 percent in fish and between 14 and 100 percent

in shellfish with a value of 61 percent in shrimps. As a general observation the

inorganic: Organic Mercury ratio decreases with the age of the fish.

Sedimentation rate along with the Hg content of particulate matter will

determine the Hg input – flux to the sediments. The adsorption mechanisms of

Hg on solid matter may be explained in terms of chemical binding in

combination with electrostatic forces of attraction. A study conducted (Boudou,

A., 2006) showed that the atmosphere input of Hg by rain washout to the ocean

is about 8 times larger than that form rivers. (Compeau, 1985) considered the

natural vaporization of Hg from the land surface to be a significant source of

Hg in the atmosphere. (Charlet, et al., 2003 ) has shown that free or inorganic

Hg is relatively lesser toxic than organic Hg, but these pose potential danger to

marine biota as they can transform into organo mercury with aldehydes. Studies

58

made on the west coast of India have shown that the Hg concentration was very

low to below deduction level (BDL) in the pre monsoon and monsoon seasons,

but there was a 100 % increase in concentration for the post – monsoon season.

Hg is removed almost completely and quantitatively from sea water by

adsorption on Fe (OH)3 or clay; the analysis of oceanic manganese nodules and

Mn ores suggest that hydrous manganese oxides also act as collectors of Hg.

59

MERCURY PROFILE TABLE 11

PREMONSOON mgL-1

MONSOON mgL-1

POSTMONSOON mgL-1

RIV

ER

INE

P1

P2

P3

P4

P5

Total

D ---- .03 0.32

P ----- .029

D------.028 .055

P------ .027

D----- .026 .053

P------ .027

D----- .025 .049

P------ .024

D------ .029 .060

P------ .031

Total .025 .049

.024

.023 .044

.021

.020 .039

.019

.018 .037

.019

.021 .042

.021

Total .050 .102

.052

.051 .103

.052

.056 .111

.055

.053 .106

.053

.054 .107

.053

.ES

TU

AR

INE

L1

L2

L3

L4

L5

D----- .03 .062

P----- .032

D----- .031 .066

P----- .035

D---- .033 .067

P----- .034

D---- .034 .069

P----- .035

D---- .035 .070

P----- .035

.031 .062

.031

.032 .063

.031

.033 .064

.031

.034 .065

.031

.031 .065

.034

.055 .111

.056

.054 .109

.055

.057 .114

.057

.055 .111

.056

.056 .114

.058

MA

RIN

E

M1

M2

M3

M4

M5

D----- .030 .062

P----- .032

D---- .031 .063

P----- .032

D---- .030 .062

P----- .032

D---- .031 .063

P----- .032

D---- .034 .068

P----- .034

.031 .063

.032

.031 .064

.033

.034 .068

.034

.034 .069

.035

.031 .061

.030

.031 .063

.032

.033 .067

.034

.035 .067

.032

.034 .068

.034

.035 .070

.035

60

The distribution pattern of Hg showed comparatively lesser

concentration in all the aquatic bodies at all seasons. The post monsoon season

indicated almost 100% increase in concentration of Hg in two water bodies viz,

the riverine and lake systems whereas the marine region showed standard

average values comparable to the riverine and lake systems at the pre monsoon

and monsoon seasons. The average concentration values observed for the

marine water was in agreement with the average global distribution pattern for

the metal at all seasons. The high concentration values noted for the riverine and

lake samples for the post monsoon season may be due to desorption of the

metal, evolution from interstitial waters, sediment extraction and low biological

uptake at low salinity conditions. The concentration distribution of Hg is also

dependent on the thermodynamic equilibrium constant and standard free energy

changes of the Hg complexes with organic and inorganic ligands It is

interesting to note that the distribution of the metal between particulate and

dissolved phases shows almost identical values, with the distribution co-

efficient KD ranging near unity. The dependence of KD is found to be

independent of the physico-chemical parameters and least influenced by change

in salinity when a comparison is made between the three distinct aquatic

environments at all seasons. This unique feature differentiates its aquatic

behavior from all the other trace metals.

The highest concentration value observed for the periyar water at the pre

monsoon season was 0.06 x103µgL

-1

(P5) and the lowest values was 0.049

x103 µgL

-1

(P4). For the Monsoon season the highest and lowest value were

0.049 x103 µgL

-1

(P1) and 0.037 x10

3 µgL

-1

(P4). For post monsoon season

.111 x103µgL

-1 (P3) and .102 x10

3 µgL

-1 (P1) respectively.

61

For the lake samples, the highest concentration values for the pre

monsoon season was 0.070 x103µgL

-1

(L5) and the lowest values was 0.062

x103µgL

-1

(L1). For the monsoon season the highest and lowest values were

0.065 x103 µgL

-1 (L5) and 0.062 x10

3 µgL

-1 (L1). For the post monsoon season

the highest and lowest value were 0.114 x103

µgL-1

(L5) and 0.109 x10

3 µgL

-1

(L2) respectively.

When the marine samples were examined for the pre-monsoon season a

highest value of 0.068 x103 µgL

-1 (M5) and a lowest value of 0.063 x10

3 µgL

-1

(M2) were noticed. For the monsoon season a highest value of 0.069 µgL-1

(M4) and a lowest value of 0.061 x103 µgL

-1

(M5)were obtained. In the post

monsoon season the highest and lowest values were 0.070 x103µgL

-1 (M5) and

0.063 x103 µgL

-1 (M1) were observed.

The highest value of concentration of Hg at an all season pattern was

0.114 x103µgL

-1

(L5) in the lake sample for post monsoon season, and the

lowest value was 0.037 x103 µgL

-1 (P4) in the Periyar sample in the monsoon

season.

62

8. DISTRIBUTION OF CADMIUM

The average abundance of Cd in the earth’s crust is 0.2 mgKg-1

(Ahrens,

1965).The average concentration of Cd in ocean water is 5 x 10-2

µgL-1

(Turekian, 1969). The worldwide anthropogenic input of Cd to fresh water

range from 2.1 to 17 x 103

metric tones per year (Living stone, 1963). Its

oceanic residence time is 5 x 105 years (Goldberg , 1965). The major specific

sources on a worldwide basis are atmospheric deposition, smelting and refining

of non-ferrous metals, manufacturing processes related to metals, and chemicals

and domestic waste water.

Cadmium is relatively mobile in the aquatic system existing as Cd2+

Cd(OH)2, (aq) Cd (OH)3, Cd(OH)42-

and CdCO3 and in various other organic

and inorganic complexes. The solubility of Cadmium hydroxide complexes

decreased as pH increases owing to the formation of solid Cd(OH)2. Since +2

valency state predominates in fresh water redox potential has little effect in

speciation.

As salinity increases Cd complexation with chloride ion also increases

until the dominant complexes all contain chloride (Nuernberg and Valenta,

1983). Sorption to suspended solids such as clay is an important, often dominant

fate process in fresh waters. Co-precipitation with hydrous Iron, Al-Mn oxides,

and Carbonate materials also occurs and periodically dominates fate processes .

(Comans and Van Dijk 1988) have reported that large scale desorption from

particulate occurs as river water mixes with sea water. A strong correlation

between Cd and PO43-

has been detected in the Gulf of California which might

be due to the association of Cd to the organic matter production and re

mineralization (Delgadillo- Hinojosa et al., 2001). Cullen et al, (1999) showed

that Cd uptake by natural phyto-plankton is inversely related to Zn

concentration in sea water. Mobilization processes occurring when river water

63

mixes with sea water lead to release of Cd from particles owing to the formation

of soluble Cd-Chloro complexes (Elbaz – Poulichet et al., 1993). For dissolved

Cd a linear relationship was found to exist between their 0.45 µm filter-passing

concentration and those of glutathione (GSH) in estuarine water maintaining a

“mild-salinity” maximum”(Degui Tang et al., 2002) . The dissolved Cd

distribution in the marine waters is being controlled by a combination of

biological cycling, Thermophaline circulation and mixing processes in a vertical

pattern. In a study conducted in the Bay of Bengal, India, the surface waters

were enriched with Cd when compared with deep water which may be due to its

correlation with nutrient and salinity. The enhanced vertical mixing near the sea

shore produces a less pronounced vertical Cd profile due to strong upwelling

process. A study made at the Coromandal coast showed high concentration of

Cd during the pre monsoon and monsoon season. This might be due to the

heavy rains carrying discharge of industrial and agricultural wastes directly into

the coast. This is substantiated by a highly significant positive correlation

between the concentration of Cd and nutrients.

64

CADMIUM PROFILE TABLE - 12

PREMONSOON mgL-1

MONSOON mgL-1

POSTMONSOON mgL-1

RIV

ER

INE

P1

P2

P3

P4

P5

Total D ---- .11 .34

P ----- .23

D------.15 .61

P------ .46

D----- .26 1.14

P------ .88

D----- 1.50 4.50

P------ 3.00

D------ 0.75 2.00

P------ 1.25

Total .56 1.3

1.27

.16 .91

.75

.13 .51

.38

.12 .49

.37

.14 .60

.46

Total .35 1.02

.67

.46 1.27

.81

.29 1.27

.98

.30 1..37

1.07

.49 1.76

1.27

.ES

TU

AR

INE

L1

L2

L3

L4

L5

D----- .67 192

P----- 1.25

D----- .56 1.93

P----- 1.37

D---- .03 . 09

P----- .06

D---- .02 .10

P----- .08

D---- .01 05

P----- .04

.11 .40

.29

.11 .39

.28

.15 . 82

.67

.13 .59

.46

.14 .51

.37

.01 .04

.03

.05 1.08

1.03

.04 1.31

1.27

.30 .90

.60

.40 1.41

1.01

MA

RIN

E

M1

M2

M3

M4

M5

D----- .01

P----- .04 .05

D---- .07

P----- 1.20 1.27

D---- .08

P----- 1.31 1.39

D---- .02

P----- .06 .08

D---- .03

P----- .06 .09

.01 .03

.02

.03 1.05

1.02

.04 1.31

1.27

.07 1.22

1.15

.08 1.28

1.20

.03 1.1

1.07

.02 .10

.08

.01 .03

.02

.04 1.27

1.23

.05 1.32

1.27

65

The distribution of Cd showed comparatively lesser concentrations with

respect to other metals in all the three aquatic environments at all seasons.

When the three water bodies are compared the riverine and estuarine systems

showed greater Cd accumulation. The particulate – dissolved distribution co-

efficient showed comparable values of other heavy metals. The hydro graphical

parameters like salinity, PH ,alkalinity, dissolved oxygen , conductivity etc. have

been observed under various conditions and the result has shown that salinity

has a greater influence on the distribution co-efficient of Cd than other

parameters. Salinity has an inverse correlation with the distribution of the metal

between dissolved and particulate.

The highest and lowest values of Cd concentration in the riverine water at

the pre monsoon, Monsoon and post monsoon seasons were 4.50 x103 µgL

-1

(P4), 0.34 x103µgL

-1 (P1) -- 1.83 x10

3µgL

-1 (P1), 0.49 x10

3 µgL

-1 (P4) ----

1.76 x103 µgL

-1 (P5), 1.02 x10

3µgL

-1 (P1), respectively.

The corresponding values for the estuarine water were 1.93 x103µgL

-1

(L2),0.05 x103 µgL

-1 (L5) ---- 0.82 x10

3 µgL

-1 (L3), 0.39 x10

3 µgL

-1 0.39

x103 µgL

-1 (L2)----1.31 x10

3 µgL

-1 (L3), 0.04 x10

3 µgL

-1 (L1) respectively .

The maximum and minimum concentration levels of Cd in the Marine

environment were 1.39 x103

µgL-1

(M3), 0.05 x103

µgL-1

(M1)----- 1.31 x103

µgL-1

(M3), 0.03 x103

µgL-1

(M1) --- 1.32 x103

µgL-1

(M5), 0.03 x103

µgL-1

(M3) respectively.

When the concentration of Cd observed in the present study was

compared with the levels reported from other regions of Indian coast, most of

the regions showed lower concentrations that the Cochin coast indicating that

increased load of Cd pollution along this coast is due to various factors such as

66

river run-off, discharge of industrial and municipal waste/anthropogenic inputs

and harbor activities. These results clearly indicate that local hydrography,

seasonal variability and physicochemical state are factors which cannot be

negleted in studies of this metal in coastal waters. The flat areas of the Periyar

river along its course have become the stretches of pollution from discharged

effluents dominated by Cd, because of the low gradient of the river and low

velocity of water flow. Since the river basin is located in the heavy rainfall

zone, contribution of chemical components from the lithogenic sources by the

leaching process to the river is substantial. The pre monsoon season is found to

be most contaminated by Cd in all the three aquatic environments, as shown by

other heavy metals but it is largely influenced by the presence of nutrients like

phosphate and nitrate. The quantification of metal contamination was attempted

by the calculation of enrichment ratio. The global average river value and the

local background were considered and the result has shown that Cd is enriched

in River Periyar against a global average.

67

C. ROLE OF MICRONUTRIENTS

The most important micronutrients needed by phytoplankton and other

aquatic plants are nitrogen, phosphorous, silicon etc. Those types of organisms,

which have silicious frustules require a supply of silicon and the blooming of

these species reduce the silicon content of water appreciably.

In addition to the dissolved molecular Nitrogen, sea water contains, low

but extremely important concentrations of inorganic and organic nitrogen

compounds, the total weight of which is about one tenth of the dissolved gases.

The principal inorganic forms of Nitrogen are nitrate ion (1-500 µg NO3- - N/L,

NO3-), nitrite ion (0.1-50 x10

3 µg NO2

- - N/L)) and ammonia (1-50 x10

3µg

NH3 – N/L,). Small amounts of other inorganic compounds have also been

shown to be present, eg, nitrous oxide (Craig and Gordon, 1963), and other

short – lived species such as hydroxyl amine and hyponitrite ion may also

occur in minute quantities. The sea also contains low concentrations of

dissolved and particulate organic nitrogen compounds associated with marine

organisms and the products of their metabolism and decay. The total amount of

ammonia present in water is the sum of ammonia and ammonium ion which are

in mutual equilibrium, the relative proportion of each depending upon the PH.

Nitrogen cycle in the sea water.

The concentrations of the various organic and inorganic nitrogen species in the

sea are controlled by biological factors. But physical effects such as the sinking

of dead organisms and upwelling tend to bring about a redistribution of these

species in the water column. In any body of the water the instantaneous balance

of the nitrogen compounds represents a dynamic equilibrium between these

68

various processes. Bacteria, plants and animals play complementary parts in the

various transformations. Bacteria dominates the regenerative process, in which

organic nitrogen compounds are converted into inorganic nitrogen species and

eventually to nitrate. Phytoplankton normally synthesize their proteins from

nitrite, nitrate and ammonia, but, bacteria only use these forms of nitrogen when

organic nitrogen is not available. Living animals contribute to the nitrogen

cycle in the form of excretion into the water of ammonia and to a lesser extent

its precursors such as urea, amino acids, trimethyl amine oxide and peptides.

Nitrogen cycle in the sea is not a closed system. Deposition of organic

nitrogen compounds in sediments annually removes 9 x 106 tons of nitrogen

from the Sea. Nitrogen fixation is endothermic and requires a plentiful supply of

organic material as energy source (Nutman, 1959). Certain blue- green algae

have been shown to fix nitrogen in tropical and subtropical waters. (Georing et

al, 1966).

2. SPECIATION OF NITROGEN IN ESTUARINE WATERS.

Some form of Nitrogen is required by phytoplankton for the synthesis of

their cellular amino acids etc. They satisfy most of their needs by utilizing the

ammonia, nitrate and nitrite present in the water. Although all three sources of

nitrogen can be absorbed by most species of phytoplankton, ammonia is used

preferentially. It has been found that even though ammonia is the result of

short-term regeneration, it is probably more important than nitrite and nitrate as

a micronutrient in the coastal waters of New England. Studies have been done

in Cochin Estuary which confirm the above finding.

The kinetics of uptake of nitrate and ammonia by natural populations of

phytoplankton in the coastal and estuarine waters have been investigated by

using nitrogen – 15 tracer techniques. They observed that there is a hyperbolic

relationship between the concentration of nitrate and ammonia and its rate of

69

uptake. Mathematically this is in agreement with Michaelis – Menten

expression used in the study of enzyme kinetics . In the estuarine waters where

a significant quantity of water is polluted by sewage disposal, the nitrogen

requirements by phytoplankton may be satisfied by the utilization of area and

uric acid.

3. DISTRIBUTION OF NITROGEN IN RIVERINE WATER.

Nutrients carries by rivers to oceans are important indicators of changing

conditions in watersheds as well as important controls on biotic activities in

estuaries and coastal seas. Riverine inputs significantly impact the salinity

distribution and circulation of the ocean and help support productive

commercial and subsistence fisheries. The various inorganic forms of Nitrogen

in the fresh water system are nitite, nitrate and ammonia. In addition to the in

organic nutrients, there is a great deal of organic matter (dissolved and

particulate) and suspended sediment flux. The high concentration level of the

nutrients is attributed to human land activities with regard to cultivation,

fertilizer application land run – off during rainy season, soil erosion etc. This

information is vital to the understanding of large – scale terrestrial

biogeochemistry and land-ocean linkages. This is used by oceanographers to

study water movement and the transport and processing of terrigenous

materials. The freshwater inputs and nutrient inputs to the estuaries and

subsequently to oceans has a key role in the characteristics of climate change

and land – use changes. The partitioning of Nitrogen between inorganic

components (Nitrite, nitrate and Ammonium) and organic components

(dissolved organic nitrogen) is a well-balanced equilibrium transformation.

70

4. PHOSPHOROUS PROFILE IN DIFFERENT AQUATIC

ENVIRONMENTS

Phosphorous occurs in sea water in a variety of dissolved and particulate

forms. Inorganic phosphate exists in the sea practically entirely in the form of

orthophosphate ion. Organic phosphorous compounds constitute a significant

proportion of the dissolved phosphorous in the upper layers of ocean. They are

formed as a result of decomposition and excretion products of marine

organisms. Sugar phosphates, phospholipids and phosphonucleotides are found

to be present in marine water. In addition to these phosphate esters containing 0-

P linkages aminophosphonic acids, which contain the much more stable C-P

bonds, may comprise a significant proportion of the dissolved organic

phosphorous present in the sea. These compounds have been detected in a

variety of marine invertebrates such as coelenterates and molluses and in a

number of species of phytoplankton. Particulate phosphate which is found to be

present as ferric phosphate which is supported by solubility product data.

Phosphate may also be present adsorbed onto particulate matter. Particulate

organic phosphorous is that associated with living or dead organisms. It may

there fore contain the whole range of organic phosphorous compounds involved

in the biochemistry of marine organisms and their degradation processes.

In estuarine and coastal waters phosphorous exists as polyphosphate ion, due to

pollution and detergents (Strickland, 1968). In estuaries , very high nutrient

level of phosphorous may build up as a result of the discharge of sewage and of

effluents containing detergents rich in polyphosphates. They may further be

augmented by phosphate introduced from the run- off water from farm land to

which excessive amounts of fertilizer have been applied. Such condition

71

frequently lead to very rapid proliferation of phytoplankton . It seems that

phosphorous is the main cause of such eutrophication . Since even in the

absence of combined inorganic nitrogen, nitrogen – fixing algae will continue to

flourish, provided sufficient phosphate is available. Most of the phosphorous

and its compounds found in river water are originated from rock-weathering and

fertilizers used for cultivation. Phosphorous compounds, such as adenosine

triphosphate and nucleotide co enzymes, play a key role in photo synthesis and

other process in plants . Absorption and conversion to organic phosphorous

compounds proceeds even in the dark. At phosphate concentrations above 10

µgL-1

the rate of growth of many species of phytoplankton is independent of the

phosphate concentration . But, as the concentration decreases below this critical

level, cell division becomes increasingly inhibited and phosphorous deficient

cells are produced . If they are supplied with phosphate they readily assimilate

it.

72

5. DISTRIBUTION OF SILICON IN WATER BODIES

Silicon is present in sea water both in solution and particulate form. The

soluble form of silicon is probably orthosilicic acid, Si(OH)4. Since polymeric

forms of silicic acid are rapidly depolymerised in sea water, they are unlikely to

occur in the sea and even in estuarine water and river water. Sea water contains

in suspension a wide spectrum of finely divided siliceous materials. Many of

them have been produced by the weathering of rocks on land and have been

transported to the sea by rivers and by wind. They included quartz, feldspars

and clay minerals. Most of them sink to the ocean floor and contribute to the

sediments. In some parts of the oceans the surface waters abound with

organisms such as diatoms and radiolarians which have skeletons of a non-

crystalline form of hydrated silica – opal. When these organisms die, their

siliceous skeletons slowly dissolve as they sink. The concentration of suspended

matter varies with geographical location, half of them being approximately

Inorganic. Highest concentrations occur in coastal ands estuarine waters

compared to sea water. It has been found that about 37-410 x103 µg Si/L of

suspended silicon in water were present in the English channel. High

concentrations of biogenic silicon is found in surface waters during diatom

blooming.

Analytical Chemistry of Nitrogen

Nitrogen is estimated in the form of Nitrite, Nitrate and Ammonia

1. Estimation of Nitrite

The water sample is treated with a solution of sulphanilamide. The

resultant diazonium ion is coupled with N-(1-Naphthyl)-ethylene diamine to

give an intensely pink azo dye, the absorbance of which is measured at 543 nm

with a spectrometer.

73

2. Estimation of Nitrate

Nitrate is usually determined by reducing it to nitrite which is determined

as described above. The reduction is carried out by treating the sample with

ammonium chloride and passing it through a glass column packed with

amalgamated or copper-coated Cd filings.

3. Estimation of Ammonia

There are two methods available for the determination of Ammonia. In

the first method, ammonia is oxidized to nitrite using alkaline hypochlorite

solution. The excess hypochlorite is then reduced with arsenite and the nitrate

is determined as decribed above. In the second method, the sample in an

alkaline citrate medium is treated with sodium hypochlorite and phenol in the

presence of catalytic amounts of sodium nitroprusside. A blue indophenol dye is

produced and its intensity is measured photo metrically.

DETERMINATION OF PHOSPHOROUS IN SEA WATER

The determination of phosphate is carried out by treatment of the water

sample with an acidic molybdate regent containing ascorbic acid and a small

proportion of potassium antimonyl tartrate. Phosphate yields a blue-purple

complex, the absorbance of which is measured at 885nm with a spectro

photometer. The reaction probably takes place with the intermediate formation

of phosphomolybdic acid , which is then reduced to a hetoropoly acid

containing phosphorous molybdenum and antimony in the ratio 1:12:1 by

atoms. Polyphosphates do not react with the reagent, but can be determined with

it after hydrolysis in acid medium at 1000C. (Strickland, 1968). Before total

phosphorous can be determined with the reagent,it is necessary to breakdown

organic phosphorous compounds to phosphate. This decomposition can be

74

most readily achieved by treating the sample with a small quantity of hydrogen

peroxide and irradiating it for a few hours with high intensity ultraviolet

radiation organically bound phosphorous is determined from the difference

between total phosphorous and phosphate – phosphorous concentrations

- (Murphy and Riley. 1962)

DETERMINATION OF SILICON

The determination of dissolved silicon in sea water depends on the

formation of yellow β -silicomolybdic acid when the sample is treated with an

acidic molybdate reagent. Only silicic acid and its dimer react at an appreciable

rate and the method therefore gives a measure only of reactive silicate. Since the

β – silicomolybdic acid is unstable and has only a low molar absorbance it is

generally reduced to the stable and the more absorbent molybdenum blue

complex and measured spectrophotometrically at 812 nm. Although the

reduction can be carried out with a variety of reducing agents, a reagent

containing metol (P-Methyl-aminophenol sulphite) and sodium sulphite is

usually used for this purpose. Phosphate produces a similiar blue complex, but

the formation of this can be prevented by incorporating oxalic acid or tartaric

acid in the reducing agent.

75

D. ANALYSIS OF SEDIMENTS

Textural characteristics of sediments were determined using pipette

analysis. The sediments were finely powdered and dried at approximately 700C

and were digested in a mixture of HF – HClO4 - HNO3 and brought into

solution by 0.5 M HCl (25 ml) in Milli – Q water. Samples were analyzed on

an AAS Flame (PE Analyst ) after calibration with suitable E-Merck elemental

standards. Precisions of the analytical procedure were checked using a triplicate

analysis of a reference standard (BCSS -1) from the National Research Council

of (Canada Precisions were 4% for Cu, Zn, Cd and Pb, 9% for Fe, Mn and Cr

and 10% for Hg. For the estimation of organic Carbon, the sample was frozen

and dried, powdered, sieved and homogenized and acidified with about 50%

HCl and gently warmed to remove Carbonates. The organic carbon and nitrogen

contents of the samples were estimated in elemental analyzer (Thermo –

Finnigan, Flash EA 1112) using L-cystine as standard. The precision of the

analysis checked against standard reference material (NIST 1941 B) and was

found to be 0.5 ± 0.1% for C.

The degree of pollution in sediments can be assessed by evaluating

various parameters like enrichment factor (EF), contamination factor (CF) and

geo-accumulation Index (I geo). To identify anomalous metal concentration

and to evaluate abundance of metals geochemical normalization of the trace

metals data to a conservative element such as Fe, Si was employed . Iron has

also been used as a consecutive tracer to differentiate natural from

anthropogenic components. Iron has been chosen as normalization element

because of its origin being exclusively litho spheric.

76

I. Enrichment Factor (EF) is defined as

EF = C

Sample ) / Fe (sample) ]

C

Crust) / Fe (Crust)]

Where C sample is trace element concentration in the sample. C crust is trace

element concentration in the continental crust, Fe sample is Fe content in the

sample and Fe crust is Fe Content in the continental crust (Taylor et al., 1995).

II Contamination Factor (CF) is defined as

CF = Metal content in sediment

Background value of Metal

Where CF < 1 refers to low contamination, 1 ≤ CF ≤ 3 means moderate

contamination 3 ≤ CF ≤ 6 indicates considerable contamination CF > 6 indicates

very high concentration .

III. Geo accumulation Index

The Geo accumulation Index(I geo) was introduced by Muller, 1969,) and

was used to assess metal pollution in sediments according to the

equation I Geo = log2 (Cn/1.5 βn) where Cn is measured concentration of metal

in the sediment, βn is Geo chemical background value in average shale of

elements, n, and 1.5 is the background matrix correction in factor due to

lithogenic effects.

When I Geo < O refers to unpolluted

I Geo = 0-1 refers to unpolluted to moderately polluted

I Geo = 1-2 refers to moderately polluted.

77

I Geo = 2-3 refers to moderately to heavily polluted

I Geo = 3-4 refers to moderately to heavily polluted

I Geo = 4-5 refers to heavily to extremely polluted and I Geo > 5 refers to

extremely polluted.

Results and Discussion

A. Sediment Texture of the Estuary, Organic Carbon and Trace Metals

Sediment Texture exhibited strong spatial and seasonal variability.

During the Monsoon season, the sand, slit and clay content in sediments of the

whole estuary varies in the ranges 0.24 – 75.34%, 0.1 – 33 % , and 0-80%.

During the Pre monsoon season, the corresponding values were 0.11 – 85%,

0.15-41% and 5-75 %. During the post monsoon season the values were0.15 –

70%, 0.12 – 33% and 3- 65% respectively.

B. Sediment Texture of River Periyar

Sediment Texture of river Periyar showed higher values of sand , slit and

clay when compared to the estuarine behavior at all seasons. During the

monsoon season, the sand, slit and clay content in the sediments showed a

variation range of 0.5 – 95%, 0.4 – 65%, 1-98% .During the Pre – monsoon

season, the corresponding values were 0.3 – 85%, 0.2 – 55%, and 2.5 to 87%.

During the post monsoon season the values observed were 0.2 – 79%,0.3 – 49%

and 3.2 – 78% respectively.

C. Sediment Texture of Marine environment

The samples collected from the Marine environment were analysed for

the content of sand, slit and clay and found to be less than those of estuary and

river samples.

During the Monsoon season the sand slit and clay contents showed a

range of 0.1 – 39%, .23% , 33% and 1-46% . During the pre monsoon season,

the values noticed were 0.1-36%, 0.21 – 32% and 1-41%. During the post

78

monsoon season, the corresponding values were 0.1-29%, 0.22 – 33 % and 1-37

% respectively.

A relatively high clayey environment was observed in the central estuary

whereas for all the other parts, a high sandy environment was noticed for all

seasons. The relatively high concentration of coarse sediment observed at the

bar mouth were due to estuarine bed- load movements associated with tides.

The high silting environment throughout the estuary found during the pre

monsoon season is an indication of sedimentation processes associated with

finer particles settled onto the bottom due to the prevailing of weak currents.

The Texture analysis of River sediment revealed that the sand, slit and

clay contents were comparatively higher than those of estuarine and Marine

samples. During Monsoon season this reached the highest value because of

heavy rain fall and water flow, high anthropogenic and agricultural activities,

sand mining, river bank dissipation, industrial and construction works done on

river side.

The Marine samples showed lesser values because of high deep sea

sedimentation, high salinity of seawater and chemical and biological

interactions taking place in seawater.

D. Organic Carbon Content.

Organic Carbon content in estuarine sediment depends on a number of

factors like rate of supply of terrestrial materials, rate of deposition of organic

and inorganic matter and their inter conversions, the various physico- chemical

parameters like salinity, redox potentials, PH , alkalinity, dissolved oxygen etc,

the primary productivity of that region etc. The dependence of organic carbon

content on the texture of sediments depends on the relative percentage

composition of sand , slit and clay contents of the sample.

Organic Carbon is found to be high in the monsoon season and relatively

low in the pre monsoon and post monsoon seasons. The values noted are (0.2 -

89%). (0.5 – 5.3%) and ( 0.6 – 2.9%) respectively.

79

For the estuary, high fluctuations are noted in the central estuary

(Average 6.9%. 3.7%, 1.8% for the monsoon, pre monsoon and post monsoon

rsptly), whereas for all the other stations (Northern, eastern, western and

southern) the values were al most steady.

The Riverine sediment showed higher values during the post monsoon

season and lowest values at the monsoon season (average: 5.4% 2.5% and 1.8%

respectively).

The Marine samples showed comparatively meagre values at an all-

seasons basis, For Monsoon, Pre monsoon and post monsoon , 0.3 – 0.8%, 0.2

– 1.2% and 0.5 – 1.5% resptly.

Organic Carbon showed positive correlation with slit and clay and inverse

correlation with sand at all seasons and all three water bodies . The positive

correlations of organic carbon is due to its size – dependent scavenging and

adsorption on clay-minerals ( Sakara Narayanan et al., 1992) The substantial

increase in the organic carbon content in the Monsoon season when compared

with the Pre monsoon and post monsoon season is attributed to the increase in

surface area of the particles. (Muller et al., 1979) An abnormal dip in the

organic carbon content in all the marine samples postulates an on inverse

correlation of organic carbon content on the high salinity of the sea water).

(Chandramohanakumar et al, 2002)

E. Trace Metal

Metals such as Fe, Mn,Co, Cr, Ni, Cu, Zn, Cd and Pb generally showed

higher concentration levels in the central and Northern parts of the estuary

during the monsoon season and relatively lower levels at the pre monsoon

season, whereas the post monsoon season showed the lowest value. The central

estuary has been shown to be extremely dynamic , whereas the others are not.

Due to large supply of industrial effluents and comparatively weak flow

characteristics all trace metals present higher concentrations in the northern part

of the estuary. During the monsoon season, since the central estuary receives

80

both domestic and industrial effluents at a moderate level coupled with strong

flow the trace metal concentrations were found to be intermediate between high

and low values, but with occasional mild fluctuations. During the pre monsoon

and post monsoon seasons, the metal concentrations showed a descending

trend, in the central estuary, but were moderate in the other parts, which could

be attributed to strong rectilinear current which maintains an effective flushing.

The Marine samples showed very low metal concentrations which could

be due to tidal variations, constant mixing of fluvial sediments with marine

sediments and other physico – chemical parameters like high salinity and low

dissolved oxygen, ocean currents and primary production.

The river samples provided high trace metal concentration in sediments

during monsoon season and lower values in the pre monsoon and post monsoon

seasons. This is due to high anthropogenic, domestic, industrial and

agricultural activities in conjunction with heavy torrential rain, soil erosion, and

river bank disintegration.

Trace metal concentrations in different regions of Cochin Estuary ,

River Periyar and Marine waters are given in the Tables.

Iron is comparatively higher in all the samples of the sediments collected

from the three different environments at all seasons. The Iron content in all the

samples is much greater than other trace metals. Iron is present in considerable

quantities in the estuarine and river waters compared to the marine sample

where it is the lowest. The concentration of Fe in the Monsoon and pre

monsoon seasons showed greater values than in the post monsoon season . Fe in

the riverine and estuarine water showed more or less similar values.

Among the other trace metals Mn and Zn showed comparatively larger

concentrations compared to the rest. Mn showed a maximum of 1815 ppm and

a minimum of 70 ppm whereas Zn showed a maximum value of 2200 ppm and

a minimum of 10 ppm. The minimum concentration level of Zn was less than

81

that of Mn whereas the maximum showed same similarity in the marine and

estuarine regions.

Co and Ni showed similar pattern and trends, the concentration of both

being very low values as expected, The highest concentrations of Co and Ni

recorded 85 ppm and 121 ppm respectively and the lowest values recorded 1

ppm and 1.1ppm respectively Cd Showed a maximum of 91 ppm and a

minimum of 0.1 ppm, whereas in three stations in the river water was Nil. Cd

recorded the poorest concentration value among all trace metals.

Cu , Cr abd Pb showed almost similiar patterns and trends, with higher

accumulation for Chromium in all the three aquatic bodies for maximum,

whereas for minimum the behavior was almost similiar . A maximum value of

414 ppm was noted in the Cochin estuary for Cr, whereas, the minimum were in

good agreement with the distribution pattern for Cu, and Pb , the minimum

being 1.7 ppm.

On a seasonal basis, the post monsoon season presented poor

accumulation of trace metals in all the three water bodies. The Monsoon and pre

monsoon seasons recorded almost similiar trends for all trace metals, but pre

monsoon values were greater than Monsoon values. No appreciable and

substantial fluctuations were noticed for the trace metals in the marine system

despite the seasonal variation. This was noteworthy for sediment features

transportation and mixing characteristics in the marine water. Seasonal

variations, mixing with river water and estuarine water has no appreciable

Impact on the sedimentation phenomena. The monsoon effect, water flow, tidal

variations, floods have little effect on riverine water sedimentation.

82

SUMMARY

In the present study, water samples and sediments from five different

stations each from riverine (River Periyar), Estuarine (cochin Estuary) and

Marine (Arabian sea) environments were studied on a seasonal basis, viz, pre

monsoon, monsoon and post monsoon seasons. The physico – chemical

parameters like salinity, temperature, dissolved oxygen, PH etc., and the

concentration levels of trace metals like Fe, Mn, Zn, Cu, Pb, Cd, Cr, Hg, Co, Ni

etc were examined in the water and sediment samples. The partitioning of the

heavy metal between the particulate and dissolved phases and the distribution

co efficient was studied for the various trace metals in the water samples. The

distribution of trace metals in the sediments and the properties like sediment

texture, organic carbon content etc were subjected for analysis. An attempt has

been made to establish the degree of pollution caused by the trace metals in the

water samples and sediments. The correlations existed between different trace

metals, trace metals and hydrographic parameters were also examined. The

important findings were compared for the three different water bodies and for

the different seasons. The distribution of Nutrients like nitrate, nitrite,

phosphate, Ammonia and silicate were also studied for the water bodies.

Salinity showed an increasing trend from riverine to estuarine and coastal

regions which, may be attributed to the combined effects of high insulation and

cessation of river water influx during the pre monsoon and high river water

influx coupled with intense precipitation during monsoon season.

Temperature, dissolved oxygen, and Nutrients showed a decreasing trend

from riverine to estuarine and coastal regions, thus exhibiting an inverse

relationship with salinity. This was reflected in the negative correlation

between D.O. and salinity and between nutrient and salinity.

83

Temp. was relatively high in summer (May) and low in winter ( Jan –

Feb) with intermediate values in September which was in accordance with the

variations in atmosphere temp.

The average concentration of D.O. was relatively high in Jan – Feb

followed by September and May. The former was attributed to the combined

effects of winter cooling and high photo synthetic activity leading to increase in

D.O in Jan – Feb and the latter was due to the decrease of solubility because of

increase of temp. and salinity of the water column during May. The average

concentration of nutrients followed the order Sept > Jan-Feb> May. Relatively

high concentration in sept. can be attributed to the combined effects of

precipitation and river run off. Lowest concentration in May may be due to

their utilization by phytoplankton in estuarine and coastal water. They

exhibited a decreasing trend from head to the mouth of the estuary during Sept.

indicating the predominant fresh water origin.

Surface depletion and bottom enrichment of the nutrients suggest their

involvement in the biogeochemical cycles namely uptake by phytoplankton

during photosynthesis at surface and regeneration in the water column through

combined effects of microbial decomposition, bio-chemical oxidation of

organic matter and remobilization into the overlying waters from the sediment

water interface.

The range and average nutrient (NO3 –N ,(NH4 – N), (PO4, - P) and SiO4

– Si ) concentrations and nutrient to salinity ratios indicates a decreasing trend

with increase in salinity.

Variations of Metal concentration with salinity indicate different patterns.

Trace metal Iron was found to be most predominant as it represented the

highest concentration values of the order of mg mg L-1

in all the environments

and at all seasons, whereas all the other metals showed a concentration level of

µgL-1

Manganese recorded the second position in all samples . The partitioning

of the metal between dissolved and particulate and the partition co –efficient

84

Kd also showed higher values for Iron and Manganese. The order of variations

of concentrations of metals in the riverine water was Fe > Mn > Zn > Pb > Cu >

Cr > Cd > Hg. For the lake water the order showed Fe > Mn > Zn > Pb > Cu >

Cr > Cd > Hg. For the marine system the order was Fe > Mn > Zn > Pb > Cu >

Cr > Cd > Hg. On a seasonal basis, the pattern was, for pre monsoon season Fe

> Mn > Zn > Pb > Cu > Cr > Cd > Hg. For the monsoon season the

concentration levels showed a variation of Fe > Mn > Zn > Cu > Cr > Pb > Cd

> Hg. A post monsoon picture was Fe > Mn > Zn > Cr > Cu > Pb > Cd > Hg. A

strong linear relationship existed between Fe and Mn which is consistent with

previous studies made in the cochin estuary and Periyar river. The Fe – Mn ratio

observed in the seawater could be used as a geochemical tracer of different

water masses of the world ocean. Concentrations of Zn, Cu, Cr, Cd, Pb were

higher in all the water samples which may be due to higher levels of these

metals in the discharges from agricultural area containing fertilizer, pesticide

and rodenticide residues . River Periyar is highly polluted due to the effluents

released into the river from a number of industries such as FACT, TCC, HIL,

Binani Zinc Limited etc. The concentration of Hg showed comparatively lesser

value in all the water samples at all seasons.

A strong metal correlation was noticed between Fe and Mn (0.401), Cr

(0.380), Zn (0.344), Cd (0.364). Similarity between Mn and Zn (0.856), Cr

(0.947), Hg(0.907) and between Cu and Pb (0.851), and Cr with Hg(0.957), Pb

with Cd (0.957) were also observed.

The flow of water discharged through the river was very low in the

premonsoon period, which causes the high concentration of metals in the lake

and river. During pre monsoon period river water discharge reduced by about 4

% , post monsoon period received about 18% of annual discharge.

The fate of heavy metals in river, lakes, estuaries near shore and off shore

Marine environments are of tremendous importance due to their impact on

aquatic life at elevated concentrations of the race metals. The Vembanad lake is

85

characterized by its large surface, shallow depth low buffer capacity, slow

horizontal mixing, resuspension of sediments which modifies the distribution

between dissolved and particulate, and redistribution between sediments and

water phase.

The metals Fe, Mn, and Pb were conservative whereas Cu, Zn, Cr, Hg

and Cd were non – conservative. For the three aquatic systems seasonal

correlation of metals with salinity was non-conservative. The metals Fe, Mn

and Pb showed positive correlations with phosphate and silicate whereas the

other metals Cu, Cr, Hg showed similar behavior, with Nitrate and Ammonium.

The metals Zn and Cd were non – conservative. No seasonal correlation existed

between metals and nutrients.

Trace metal concentration action in River Periyar and cochin estuary

have been explored extensively by a couple of researchers earlier

(Meenakumari, et al, 1980) The results of all these studies are in good

agreement with the present study. Similar results were obtained for the study of

trace metal distribution in the North Australian coastal zone, in Bynoe river (

Munsksgaard, N.C. et al 2001) A positive correlation exhibited between Ni-Cu

showed coupling to nutrient cycles ( Apte et al, 1998) Trace metal Flux in pearl

river estuary (Liu, W.X, et al, 2003) , Heavy metal pattern in Texas Estuary (

Sharma, V.K. et all, 1999), distribution of nutrients and major elements in

riverine, estuarine and adjoining coastal waters of Godvari, Bayof Bengal

(Padmatavati, D et al 1999), Trace metal distribution of heavy metals in

estuaries of southeast coast of India (Balasubramanian, T et al, 1997) A

comparative study of AAS and ASV for Trace metal Zn, Cd , Pb and Cu in

coastal waters of Visakhapatnam, east coast of India ( Prabhakara Murthy, PVS

et al, 1999) Transport and transformation of trace metals in the Scheldt estuary

(Hugues pancot et al., 1997), Heavy metal distribution in pondichery harbor,

south east coast of India ( Senthilraman et al., 1999) , Chromium distribution in

the Arctic and the Atlantic oceans and a reassessment of the oceanic Cr cycle

86

(Waraporn Sirinawin et al., 2000), Distribution and partitioning of trace metals

(Cd, Cu, Ni, Pb, Zn) in Galveston Bay waters ( Degui Tang et al.,2002),

preliminary assessment of the distribution of trace elements (Cd, Cu, Fe, Ni,

Pb, As and Zn) in a estuary (Russia) (Marine, J.M. et al., 1993) Speciation of

dissolved and particulate Mn in thee seine river estuary ( Ouddane, B et al.,

1997), Chemical speciation of Cu and Zn in the surface waters of the western

Black sea (Francois, L.L Mullar et al, 2001), Chromium in San Franscisco Bay,

superposition of geochemical processes complex spatial distribution of redox

species (Khalil E. Abu sab et al, 1995), Metal fluxes through strait of Gibraltor

the influents of Tinto and ) diel rivers in Spain (Franscois Elbaza poulichet et al

2001) Biological uptake and assimilation of Iron by marine plankton,

influences of micronutrients ( Wen-Xiong Wang et al, 2000) Cd enrichment in

the Gulf of California) Delga dillo – Hinojosa, F et al, 2001, Trace metals, As

and isotopes in dissolved and particulate phases of North Australian coastal

and estuarine sea water (Munks guard, N.C. et al, 2001.

Trace metal distribution patterns in sediments and water showed that

Iron was predominant in both media in appreciably larger quantities compared

to the other metals which is in good agreement with earlier studies Zinc

dominated in sediments whereas Mn dominated in the aquatic media. The other

metals showed different distribution patterns in water and sediments. The

metal distribution between water and sediments showed dissimilar patterns

which is attributed to partitioning of the metal between dissolved and

particulate in the water liquid phase, the speciation forms and their relative

stabilities, solubilities, ionic strengths, dependence on the hydrographical

parameters etc., and tendency for sedimentation in the solid phase. The marine

system showed poor sediment flushing conditions whereas the riverine and

marine systems showed greater sedimentation transport. Adsorption of metals in

the sedimentary compartments like slit, clay and organic carbon was appreciable

in the Cochin Estuary vis - s - vis the other water bodies . On a seasonal basis,

87

the study reveals that pre monsoon season carried greater accumulation of

metals whereas the post monsoon the least.

All the above studies have shown that the concentration of trace metals

are of the same range or even greater than that observed in other water bodies

observed world wide making this as a highly impacted region.

88

CONCLUSION

The present study was aimed at evaluating the concentrations of trace

metals and nutrients and the influence of hydrographical parameters on them in

different aquatic environments, viz. riverine, estuarine and marine water

bodies on a seasonal basis. The study was centered around river Periyar,

Cochin Estuary and off shore waters of Arabian sea. The trace metal

concentrations are found to be on a par with or mildly greater than that of

worldwide distribution pattern, but has not reacted an “extreme” level. The

concentration was above the permissible limits of Bureau of Indian Standards

(BIS), WHO standards and U.S. Environmental Protection Agency (USEPA).

Toxic pollution from heavy metals originate from the chemical discharges of

about 250 industrial units in and around Eloor, about 15 Kms from Cochin, the

“Queen of the Arabian sea” . spreads through air, soil and water in river Periyar,

,Vembanadu lake and to the Arabian sea. This leads to large scale devastation

of aquatic life, depletion of agricultural wet land, and deterioration of health of

the population. The magnitude of trace metal has been increasing considerably

over the last few decades. Industrial , domestic and agricultural pollutant

sources are likely to cause increasing problem in the future. For the proper

conservation of Vembanad lake, the effluent discharge should be minimal and

should be under strict monitoring of pollution control board. Eutrophication,

organic and inorganic pollution, reclammation etc. are causing a big threat to

Cochin backwaters, Periyar river and adjoining coastal regions. This study is a

baseline for future research in this regard and the entire aquatic net work

should become a pristine region for the promotion of economic development in

Kerala,the “God’s own Country.

89

AVERAGE TRACE METAL CONCENTRATION IN RIVERINE ENVIRONMENT

Dissolved

particulate

Total

C 15

O 14

N 13

C 12

E 11

N 10

T 9

R 8

A 7

T 6

I 5

O 4

N 3

2

1

0

Fe Mn Cu Zn Cr Pb Hg Cd

90

AVERAGE TRACE METAL CONCENTRATION IN LAKE ENVIRONMENT

Dissolved

Particulate

Total

C 15

O 14

N 13

C 12

E 11

N 10

T 9

R 8

A 7

T 6

I 5

O 4

N 3

2

1

0

Fe Mn Cu Zn Cr Pb Hg Cd

91

AVERAGE TRACE METAL CONCENTRATION IN MARINE ENVIRONMENT

Dissolved

Particulate

Total

C 15

O 14

N 13

C 12

E 11

N 10

T 9

R 8

R 7

A 6

T 5

I 4

O 3

N 2

1

0

Fe Mn Cu Zn Cr Pb Hg Cd

92

AVERAGE TRACE METAL CONCENTRATION IN PRE MONSOON SEASON

Dissolved

Particulate

Total

C 15

O 14

N 13

C 12

E 11

T 9

R 8

A 7

T 6

I 5

O 4

N 3

2

1

0

Fe Mn Cu Zn Cr Pb Hg Cd

93

AVERAGE TRACE METAL CONCENTRATION IN MONSOON SEASON

Dissolved

Particulate

Total

C 15

O 14

N 13

C 12

E 11

N 10

T 9

R 8

A 7

T 6

I 5

O 4

N 3

2

1

0

Fe Mn Cu Zn Cr Pb Hg Cd

94

AVERAGE TRACE METAL CONCENTRATION IN POST MONSOON SEASON

Dissolved

Particulate

Total

15

C 14 0 13

O 12

N 11

C 10

E 9

N 8

T 7

R 6

A 5

T 4

I 3

O 2

N 1

0

Fe Mn Cu Zn Cr Pb Hg Cd

95

AVERAGE NUTRIENT CONCENTRATION - NO3 - N

Surface

Bottom

1

C .9 13

O .8

N .7

C 1

E . 9

N . 8

T .7

R . 6

A .5

T . 4

I .3

O . 2

N . 1

0

R L M Pr M o Po

96

AVERAGE NUTRIENT CONCENTRATION - NH4 - N

Surface

Bottom

1

C .9 13

O .8

N .7

C 1

E . 9

N . 8

T .7

R . 6

A .5

T . 4

I .3

O . 2

N . 1

0

R L M Pr M o Po

97

AVERAGE NUTRIENT CONCENTRATION - PO4 - P

Dissolved

Particulate

1

C .9 13

O .8

N .7

C 1

E . 9

N . 8

T .7

R . 6

A .5

T . 4

I .3

O . 2

N . 1

0

R L M Pr M o Po

98

AVERAGE NUTRIENT CONCENTRATION - SiO4

Dissolved

Particulate

1

C .9 13

O .8

N .7

C 1

E . 9

N . 8

T .7

R . 6

A .5

T . 4

I .3

O . 2

N . 1

0

R L M Pr M o Po

99

SEDIMENT ANALYSIS

SURFACE

BOTTOM

TRACE METAL LEVELS IN DIFFERENT REGIONS OF RIVER PERIYAR

PRE MONSOON MONSOON POST MONSOON

R1 R2 R3 R4 R5 P1 P2 P3 P4 P5 D1 D2 D3 D4 D5

Fe% 0.1

2.0

0.2

2.1

0.1

2.2

0.1

2.1

0.2

2.3

0.2

4.2

0.3

4.2

0.3

4.1

0.4

3.9

0.5

4.5

0.1

0.5

0.1

0.4

0.2

0.4

0.1

0.5

0.1

0.5

Mn

(PPm)

150’

1001

151

978

155

950

187

940

176

935

200

780

210

750

205

815

204

795

206

765

75

510

80

560

85

552

70

515

81

578

(C0

PPm)

2.1

46

2.2

38

2.7

44

2.0

37

2.5

41

8.5

31

9.1

32

10.1

39

8.7

24

9.3

27

1.5

6.1

1.6

6.2

1.4

6.3

1.1

6.5

1.0

6.0

Cr

(PPm)

12

210

14

212

15

250

16

265

12

202

20

310

21

275

26

213

21.1

200

22.2

98

4.1

98

4.2

86

3.5

75

3.7

78

4.5

99

Ni

(PPm)

1.5

50

1.5

56

1.7

44

1.1

3.7

1.1

38

5.5

111

5.6

121

6.9

115

9.8

105

10.0

121

1.4

55

1.5

54

1.4

59

6.1 1.2

66

Cu

(ppm)

5.2

100

6.1

111

7.1

120

6.0

131

7.1

145

10.1

100.1

11.1

101

12.3

108

9.8

157

138 2.1

65

2.2

68

3.1

77

3.7

76

3.8

84

Zn

(PPm)

10

1531

11

1630

11

1718

12.1

1430

13.1

1378

20

1201

13.1

1315

36

1400

45

1114

53

1234

10

75

11

845

12.3

83

14.5

96

16.7

107

Cd

(PPm)

0.7

44

0.8

37

0.5

46

0.4

54

0.9

61

0.2

25

0.3

27

0.4

29

0.3

38

0.4

44

0.1

0.5

0.1

0.4

Nil

Nil

Nil

Nil

0.1

Nil

Ph

(PPm)

5.5

86

7.1

71

8.9

75

9.1

43

10.1

98

5

65

9

99

4

101

3

88

2

44

1.1

20.1

1.7

21.2

1.3

3.2

1.5

33.4

1.9

35.7

100

SEDIMENT ANALYSIS

TRACE METAL LEVELS IN DIFFERENT REGIONS OF MARINE ENVIRONMENT

PRE MONSOON MONSOON POST MONSOON

M1 M2 M3 M4 M5 M1 M2 M3 M4 M5 M1 M2 M3 M4 M5

Fe(%) 0.2

1.1

0.2

1.2

0.1

1.5

0.2

2.0

0.5

2.1

1.9 0.5

2.1

0.1

1.9

0.5

2.1

0.4

1.7

0.3

1.9

0.2

1.7

0.5

1.8

0.6

1.9

0.5

2.1

Mn(PPm) 101

715

106

710

121

832

131

650

149

774

100

615

156

778

177

695

140

615

110

803

101

610

98

715

88

800

75

605

64

704

Co (PPm) 1.5

20

2.1

21

2.0

47

1.7

39

1.9

42

2.2

35

1.9

44

2.3

50

2.7

26

2.9

37

1.7

38

2.1

47

2.0

65

2.1

49

2.7

53

Cr(PPm) 5.1

165

6.1

169

7.2

212

3.4

232

1.7

247

1.9

136

2.1

137

4.4

159

5.5

219

7.6

250

6.6

155

8.4

76

3.4

285

1.7

300

1.9

302

Ni(PPm) 1.4

44

1.5

56

1.6

47

1.7

63

1.9

76

1.3

41

1.5

45

1.4

59

1.9

46

2.1

33

2.0

47

1.9

59

2.8

61

1.7

64

1.9

71

Cu)ppm) 4.1

100

4.2

111

5.7

114

6.1

121

7.1

176

4.3

99

5.4

114

39

132

4.1

147

4.8

165

4.1

121

6.7

140

6.1

167

7.1

175

7.3

159

Zn(PPm) 12

1400

14

1359

13

1516

19

1437

21

1316

15

1415

17

1768

22

1498

44

1312

22

1476

31

1200

27

1576

28

1405

43

1584

41

1600

Cd(PPm)

0.5

40

0.4

35

0.7

38

0.9

44

1.0

49

1.1

56

0.7

46

0.9

56

1.1

44

0.8

37

1.1

48

0.8

67

0.7

75

0.9

88

1.1

91

Pb()PPm) 4.1

88

5.1

86

6.7

92

4.5

101

6.8

78

4.7

79

3.2

98

4.1

111

4.7

121

5.1

104

2.7

85

5.3

84

5.4

96

6.3

87

6.9

99

101

SEDIMENT ANALYSIS

TRACE METAL LEVELS IN DIFFERENT REGIONS OF COCHIN ESTUARY

PRE MONSOON MONSOON POST MONSOON

L1 L2 L3 L4 L5 L1 L2 L3 L4 L5 L1 L2 L3 L4 L5

Fe(%) 0.4

4.0

.21

3.5

0.3

3.6

.02

3.9

0.1

0.3

0.1

0.3

01

4.5

1.5

4.5

1.1

4.9

0.5

5.4

0.1

.35

1.2

.48

1.2

1.6

0.1

1.8

0.5

2

Mn(PPm) 210

1200

215

1316

240

1119

118

1268

206

1432

315

1800

220

1615

370

1815

415

1920

276

1760

108

815

104

718

112

839

115

872

178

915

Co (PPm) 3.5

51

49

48

5.1

56

6.9

48

7.1

44

12

57

44

55

16

61

19

85

22

66

2.1

12

3.3

8.5

3.4

9.6

4.5

11.1

4.9

9.7

Cr(PPm) 16

215

19

222

31.6

202

25.6

214

29.1

234

28

310

24

316

25

414

19

385

22

378

5.5

114

5.6

118

6.9

121

2.3

140

4.3

119

Ni(PPm) 2

80

2.5

78

2.4

67

3.1

78

4.6

7.4

7.5

120

7.9

114

6.5

101

11.1

99

12.5

114

1.5

64

1.8

61

1.7

78

1.74

64

1.5

54

Cu)ppm) 7

120

7.5

119

8.9

118

11.6

12.1

12.5

10.6

4.6

126

9.8

131

0.9

140

8.9

121

7.9

140

2.5

65

3.4

71

4.6

68

49

74

5.1

61

Zn(PPm) 15

1400

124

2150

48

1960

47

209

65

1805

12

1708

15

1414

27

1615

35

1704

48

1215

14

78

18

84

21

79

26

64

34

75

Cd(PPm)

0.8

52

0.7

48

0.9

46

1.1

44

1.7

52

0.2

35

0.3

33

0.4

37

0.8

41

0.9

39

0.1

5.6

0.1

7.6

0.1

48

0.3

9.6

0.9

8.5

Pb()PPm) 10.1

98.1

11.2

97.6

12.3

92.4

9.7

95.1

8.7

94

7

75

8.1

76.1

9.7

74.1

8.3

72.1

9.7

70.3

9.7

70.3

1.8

21.7

1.7

20.6

1.5

24.3

1.6

22.1

102

AVERAGE TRACE METAL CONCENTRATIONS IN RIVER, LAKE, MARINE, PRE MONSOON, MONSOON , POST MONSOONS

R mgL-1

L mgL-1

M mgL-1

Pre mgL-1

Mon mgL-1

Post mgL-1

Fe 12.35 13.56 15.67 12.35 11.96 10.89

Mn 4.962 5.132 6.89 4.76 4.87 3.55

Cu 2.70 3.00 2.81 3.12 5.21 4.92

Zn 4.25 3.60 4.05 4.35 3.01 2.87

Cr 4.70 9.81 2.35 9.88 5.04 6.39

Pb 2.30 4.92 5.18 4.97 4.86 2.65

Hg 0.111 0.114 0.070 0.080 0.069 0.114

Cd 4.50 1.93 1.39 4.48 1.71 1.68

R – River L – Lake M - Marine

103

PEARSON CORRELATION CO – EFFICIENTS BETWEEN METALS

Fe Mn Cu Zn Cr Pb Hg

Fe

Mn

Cu

Zn

Cr

Pb

Cd

Hg

1.000

0.401

0.218

0.344

0.380

0.186

0.364

0.009

1.000

0.544

0.856

0.947

0.463

0.22

0.907

1.000

.574

.740

.851

0.041

.666

1.000

.105

0.054

0.0026

0.105

1.000

0.489

0.023

0.957

1.000

0.957

.956

1.000

.540

104

CORRELATION BETWEEN HYDROGRAPHIC PARAMETERS, NUTRIENTS AND TRACE METALS

SALINITY DO PH

TEMP NO3-N NH4-N PO4-P SiO4 0 Si

Fe(12.35)

Mn((4.96)

Cu(2.7)

Zn(4.25)

Cr(4.7)

Pb(2.3)

Hg(.111)

Cd(4.5)

- .129

- .326

- .592

- .376

- .340

- .695

- .069

- 355

- .607

- .661

- 0.36

- .566

- .626

- 306

- .014

- 0.6

0.599

.670

.364

.574

.635

.310

.015

.608

0.561

.215

.117

.184

.204

.100

.004

.195

0.369

.091

.168

.107

.097

.198

0.243

.101

.069

.173

.319

.203

.183

.375

0.128

.191

.041

.104

.191

.121

.110

.225

0.214

.115

.017

.043

.08

.050

.045

.093

.513

.048

105

NUTRIENT DISTRIBUTION – AVERAGE CONCENTRATION

µ mol l-1

(R)

µ mol l-1

(L)

µ mol l-1

(M)

µ mol l-1

Pre

µ mol l-1

Mon

µ mol l-1

Post

N03 – N .456 .512 .323 .491 .376 .389

NH4 – N .863 .914 .713 .875 .798 .816

PO4 – P .518 .620 .706 .586 .425 .451

SiO4 – Si .216 .296 .329 .239 .201 .208

106

STANDARD REF. VALUES FOR TRACE METAL CONCENTRATIONS

WHO

mg L-1

USEPA

mg L-1

BIS

mg L-1

Iron

Mn

0.300

0.050

0.300

0.050

0.300

0.100

Zn

Cu

3.000

2.000

5.000

1.300

5.000

0.050

Cr

Pb

0.100

0.015

0.100

0.010

0.050

0.050

Cd

Hg

0.005

0.002

0.005

0.001

0.020

0.020

Co

Ni

0.030

0.060

0.030

0.020

0.020

0.020

108

REFERENCES

Abu – Saba, K.E, and Flegal, A.R (1995), Chromium in San Francisco Bay:

Superposition of geochemical processes causes complex spatial

distribution of redox species, Marine Chemistry 49 (1995) 189 -199

Ahrens, L.H., (1965), Distribution of the Elements in our planet, Mc Graw Hill,

New York

Allen, A.G, Radojevic, M., Harrison, R.M. (1998) Atmospheric speciation and

wet deposition of Alkyl lead compounds. Environmental science and

Technology 22: 517 – 522

Alloway, R.J. (1990) Heavy metals in soils, Blackie and Son, London, pp 339

Ambrose, R.F., Cohin, T. and Que Hee, S.S. (2001), Trace metals in Fish and

Invertebrates of three California coastal wetlands, Mar Poll,Bulletin Vol

.42 No 3, 224- 232

Anderson , M.A, Morel, F.M.M. and Guillard , R.R.L, (1978) Growth limitation

of a coastal diatom by low Zinc ion activity, Nature, 276 : 70 – 77

APHA (1985). The Seas (M.N.Hill, ed) Vol.3 Inter science, New York

Aston, S.R, and Chester, R, (1973), The influence of suspended particles on the

precipitation of iron in natural waters, Est, coastal Mar Sci, 1-225-231

Bacon, M.P. and Anderson, R.F., (1982). Distribution of Thorium isotopes

between dissolved and particulate forms in the deep sea J.Geophys

Res. : 87: 2045-2056

Balistrieri, L, and Murray, J.W., (1981).The surface chemistry of Goethite in

major ion sea water, Am. J.Sci, 281 : 788-806

Barth , T.W., (1952). In “Theoritical petrology” John Wiley, New York

Benoit, (1994), partitioning of Cu, Fe, Zn and Mn between filter retained

109

particles colloids and solutions in six Texas estuaries. Marine Chemistry

Vol.45(307-336)

Muresan B: 92006) Mercury Geochemistry in the petit reservoir and sinnamany

estuary University of Bordeaux, PhD Thesis, 2006 : 264

Sen Gupta, R, Sing balm S.Y.S., Sanzgirg, S., (1978) Indian Journal of Marine

Science, 7:295.

Boudou . A, Diminique Y, Cordier S., (2006). Less Chercheeurs d´or et la

pollution Par le Mercure en Gurgane francaise: envisn Risques Sante,

5: 167 – 179

Bourg, A . C.M (1983). Role of fresh water/sea water mixing on trace metal

adsorption, Trace metals in sea water, Plenum press, New York PP.(195-

208)

Bowen, Hi J.M., (1985). The natural environment and biogeochemical cycles.

In: Hutzinger, D.(ed). The Hand book of Environment Chemistry

Springer – werlag, N.Y., I, part D .pp 1-26

Boyle, E.A, Edmond, J. M and Sholkovitz, E.R., (1977). The mechanaism of

Iron removed in estuarine Geochim Cosmochim Acta, 41 : 1313-1324

Brewer, J.B.Ryan, R.L,Pazirandeh.M(1977), Comparison of ion – exchange

resins and biosorbens for the removal of heavy metals from plating

factory wastewater,Envir, science, Tech Vol.31 (2910 -2914)

Bruland K.W., (1983), Trace Elements in sea water in : Chemical

Oceonagraphy, Vol.8., Riley, J.P. and Chester , R. Ed. Academic Press,

London, 157 – 215

Bryan, G.W. (1984) in Marine ecology, edited by O. Kinre (John Wiley and

Sons, New York.

Burns, R.G., (1995) mineralogial applications of Crystal Field theory.

110

Cambridge Univ. Press, Cambridge, M.A, 551 pp

Burton, J.D and Liss, P.S. (1976). In. Estuarine Chemistry academic Press,

New York

Charlet L, Rumbach G: (2003) Solid and aqueous mercury in remote river

sediments; J Phys. 107(1): 281 – 284. IV, XII th

Campbell, P.G.C (1998) Interactions between trace metals and aquatic

organisms critique of the free – ion activity model. Wiley Chichester –

45-102

Comans, R.N.J., Van Diyk, C.P.J., (1998). Role of complexation process in Cd

mobilization during estuarine mixing Nature . 336 : 151 – 154

Compeau G. Bartha R (1985) Principal Methy lators of Mercury in anoxic

estuarine sediments. Appl, Environ Microbiol, 50:498 – 502

Coonley, L.S.Jr, Baker, E.B. and Holland, H.D, (1971) Iron in the Mullica

River and estuary , Linnoil Oceanology, 25:1104- 1112

Craston, R, E, and Murray, J.W, (1980), Chromium species in the Collumbia

River and eatuary Limnol, Oceanogr, 25 : 1104 – 1112

Danielsson L.G., Magnussom, B., Westerland, S. and Kerongzhang, (1983).

Trace metals in Gotta river estuary. Est. coastal shelf. Sci, 17, 73-85

Dash, D.R, and sahu, B.K. (1999). Specification of Copper in surface waters of

the Rushokulya estuary, east coast of India, Indian jour. Of Mar. Scis

Vol. 28. Pp.370-374

Decho, A.W. and Luoma, S.N., (1994). Humic and fulvic acids : sink or sources

in the availability of metals to the marine bivalves.Mar . Ecol. Prog. Ser.,

108 : 133-145

Degio Tang., Kent W. Warnken., Peter .H. Santchi., (2002). Distribution and

partitioning of trace metals (Cd, Cu, Ni, Pb, Zn) in Galveston Bay

111

Waters, Marine Chemistry, 78: 29-45

Delgadillo – Hinojosa, F., Macias – Zamorah, J.V, Segovia – Zavala, J.A.,

Torres – Valdes, S., (2001) Cadmium enrichment in the Gulf of

California, Marine Chemistry, 75 : 109 -122

Decho, A.W. and Luoma, S.N., (1994). Humic and fulvic acids: sink or sources

in the availability of metals to the marine bivalves Mar.Ecl Prog, Ser

108: 133-145

Donat, J.R., Bruland, K.W., (1995) Trace elements in the oceans. Trace

elements in natural waters CRC press Boca Raton, FL, PP. 247 – 281

Duinker, J.C., Wollast, R., Billen, G., (1982) Behaviour of Manganese in the

Rhine and Scheldt estuaries. II geochemical cycling Estuarine coastal

Mar. Sci. 9 727-738

Elbaz - Poulichet, F., Thomas., A.J., Gordev, V.V., (1993) preliminary

assessment of the distributions of some trace elements in a pristine

aquatic environment: The Lena River estuary (Russia), Marine

Chemistry. 43: 185-199

Feeby,Massoth, Baker (1988). Seasonal and vertical variation of Trace elements

in SPM: Washington, Estuarine Coastal shelf Sci-215-239

Fairbridge (1980): The estuary : Definition and geodynamic cycle John Wiley,

Newyork 1035

Flemminbg B.W 2000 A revised textural classification of muddy sediments:

Cont Shelf Resi:20: 1125- 1137

Forstner, U., Schoer, J., and Khauth, H.D., (1990). Metal pollution in the tidal

Elbe river, Sci Total Environ, 97/98, 347 0348

Francois, B., Renevan, G., and Lutz B., (1993). Geochemical characterization of

recent sediments in the Baltic sea by bulk and electron microprobe

analysis Mar. chemistry 42: 223 – 236.

112

Fukai, R and Huynh – Ngoc, L., (1968). Studies on the chemical behavior of

radio nucleids in seawater. “Radioactivity in the sea”. Safety series

publication No.22 International atomic Energy Agency, Vienna.

Garrels, R.M. and Mackezie, F.T., (1971), In : Evolution of sedimentary

Rocks”. Norton, New York.

Gibbs, R.J., (1977)./ Transport phases of transition metals in the Amazon and

Yukon rivers, Ball Geol.Soc.Am, 88 : 829-8743

Goldberg . E.D., (1965) Marine geochemistry, Chemical Scavengers of the sea.

J.of Goel., 62 : 249 – 265

Govindasamy C., Viji Roy, A.G., Azariah, J., (1998). Int. J. Ecol Envir. Sci 24,

141.

Grasshoff, K Ehrhardt, M., and Kremling, K., (1983) Methods of seawater

Analysis, Verlag – Chemie, Weinheim

Hart, B.T., and Davies, S.H.R., (1981). Trace metal speciation in the freshwater

and estuaries regions of the Tarra River, Victoria Est. Coastal shelf Sci.,

12 : 353 – 374

Hunt C.D., (1983). Incorporation and deposition of Mn and other trace metals

by flocculant organic matter in a controlled marine eco system Limnol.

Oceanogr, 28 (2)

Hunter, K.A, (1983). The adsorptive properties of sinking particles in the deep

ocean. Deep Sea Res, 30 : 669 – 675

IS: 10500., (1983). Indian Standard specification for drinking water. Indian

Standards Institution, New Delhi.

Kieber, R.J., and Helz, G.R., (1972). Indirect photoreduction of aqueous

Chromium (VI), Environ Sci. Technical , 29 : 307 -312

113

King J K, Gladden J.B. (2002): Mercury removal in wetland mesocosms.

Chemosphere, 46: 859 – 870

Knudsen, M.(1901). me conference International pour L’Exploration dela

Mer, Report Supplementary.

Kreming, K., and Hydes, D., (!988). Continent Shelf Res.,8:89

Krauskopf, K.B., (1956). Factors controlling the concentration of thirteen rare

metals in sea water. Geochim, Cosmochim, Acta. 9:1 -32 B

Lakashmanan, P.T., Balchand, A.N., and Nambisan, P.N.K. (1982). Distribution

and seasonal variation of temperature and salinity in Cochin Back waters.

Indian J. Mar.Sci, 11:173

Laperche V., Callier, L (2007): Reprtition du mercure clans les sediments et les

poisons de six fleuves de guv ane-Rapport BRGM edition 200

Laperche V., Callier L (2007): Repartition du mercure dans les sediments et les

poisons de six fleuves de guyane – Rapport BRGM edition., 200

Leal F.C. Teresa, M., Vasconcelos S.D., (2001) Seasonal variability in the

Kinetics of Cu, Pb, Cd and Hg accumulationby microalgae

74 (1)pp. (65-85)

Livingstone, D.A., (1963). Chemical composition of rivers and lakes. Prof Pap.

U.S. Geol Surv . 440 – 6: pp 64

Lowenstam, H.A., (1963) In: “Earth Sciences”, (T.W. Donnelly. Ed), P. 137

rice university press, houston texas.

Maest, A., Brantly, S ., Bauman, P., Crerar, D., (1984) Geochemistry of Metal

transport in the Raritan River Estuary, New Jersey, Bull N.J. Acad. Sci.

29 : 69-78

Mc. Kee, J.D., Wilson, T.P., Owen, R.M. (1989) Geochemical partitioning of

Pb, Zn, Cu and Fe across the sediment - water interface in large lakes.

114

Journal of great lakes. Research , 15: 46-58

Maqbool, T.K., (1983) studies on the biology of theclam Marcia optima gmelin

from Kayankulam lake. Ph.D. Thesis, Cochin University of Science and

Technology.

Martin, J.H. and Knauer, G.A, (1982) Manganese cycling in north east pacific

equatorial waters, J. Mar. Res. 40: 1213 – 1225

Mayer, L. H., (1982). Retention of riverine iron in estuaries, Geochim

Cosmochim,, Acta, 40 : 1003-1009

Moore, J.W., (1991). Inorganic contaminants of Surface water research and

monitoring priorities, Ed. R.S. Desanto, Springer – Verlag, Berlin pp

Morel FMM, Amyot M (1998): The chemical cycle and bioaccumulation of

Mercury Annu Rev Ecol syst. 29:L 543 – 566

Mero , J.L., (1965). In : The Mineral Resources of the sea. New York, Elsevier

Mc. Allister, C.D. Parsons, T.R, and Strickland, J.D.H., (1961). Measurement

of primary production in coastal sea water Limnol. Oceanology,

6: 237 – 258.

Muresan B: (2006) Mercury Geochemistry in the petit reservoir and University

of Bordeaux, Ph.D Thesis 2006: 264

Murray, J.W., Spell, B., and Paul, B., (1983). The contrasting geochemistry of

Mn and Cr in the eastern tropical Pacific Ocean In : Trace metals in sea

water, NATO Conf. Ser. 4: pp 643-670 Mar. Sci. V.9. Plenum

Murthy , P.V.S.P., and Satyanarayana, D., (1999) Determination of trace metals

in coastal waters of Visakapatnam – A Comparative study of AAS and

Asv techniques. Ind. J. Mar. Sci., 28 : pp . 365 – 369.

Nitta, T., (1992). In : Marine Pollution and sea life, edited by M. Rulvo

115

(Fishing News (Books)Ltd, Farmharm

Nraigu, J.D., Pacyana, J.M. (1988) qualitative assessment of worldwide

contamination of air, water and sediments of trace metals, Nature

333:

Nuernberg, H.W., Valenta, P., (1983) potentialities and applications of

voltametry in chemical speciation of trace metals in the sea. In: Trace

metals inseawater plenum, New York 671-697

Olsen, C.R, Cutshall, N.H., and Larsen, F.L. (1982) Pollutant particle

association and dynamics in coastal marine environments, A review Mar,

Chem., 11: 501 – 533

Paul , A.C. and Pillai, K.C., (1983 A.) Trace metals in a tropical river

environment : distribution. Water Air Soil Pollut. 19: 63 – 73

Pritchard, D.W., (1967.) What is an estuary : Physical viewpoint in estuaries ed.

G.H.Lauff. American Association for the Advancement of Sciences,

publication No.85. Washington pp. 3-5

Ramelow, G.J, Himel, L.L., Fradick, Y.Z., Tong. C, (1993). The analysis of

Dissolved metals in natural lwaters on biosorbents of immobilized lichen

and seaweed biomass in Silica, Int Jour. Anal. Chem,. 53 : 219-232

Riley, J.P. and Chester, R., (1971). Introduction to Marine Chemistry, PP 465,

Academic Press, London.

Riley J.P., and Chester, R., chemical oceanography. Vol.8. Academic Press

London.

Ronald Eislar, (1981). Trace metal concentrations in marine organism,

Pergamom Press N.Y.Z.

Sadiq. S., (1992) Toxic metal chemistry in Marine environment. Marcel

Dekker, New York

Salomons, W., and Fostner, U., (1984) Metals in the hydrocycle. Springer, New

116

York. Pp.349.

Samanidou, V., Fytianos, K., (1987) partitioning of heavy metals into selective

chemical fractions in sediments from rivers in northern Greece.

Sampathkumar, P., and Kannan. L. (1994). Environ Apl. Biol. 1 : 225

Sankaranarayan, V.N, and Quasim, S.Z., (1969). Nutrients of Cochin

backwaters in relation to environment characteristics. Mar Biol ., 2

236-247

Sathyanaryana D., Prabhakara Murty, P.V.S., (1999) A comparative study of

AAS and ASV for the determination of trace metals Zn, Cd, Pb and Cu in

coastal waters of Visakhapatnam, east coast of India. Indian journal of

Marine Sciencss. Vol. 28, December 1999, PP. 365-369

Sen Guptha, R., Singbal, S.Y.S. Sanzgiry, S., (1978) Indian Journal of Marine

Sceince, 7:295.

Senthilnathan, S., and Balasubramanian, (1999) Heavy metal distribution in

Pondichery harbor. Ind. Jour. Mar. Sci 28:PP. 380-382

Shibu, M.P., Balhand, A.N. and Nambisn P.N.K.91990) Sci Total Environ

97/98 : 26)

Shiller, A.M., Boyle, E.A., (1987) Trace elements in the Mississipi river delta

outflow region, behavior at high discharge. Geochim. Cosmohim, Acta

55, 3241 – 3251

Sillen , L.G., (1963). In : Oceanography Sears, M., ed, Am. Ass.Adv. Sci

Washington D.C.

Spencer, C.P., (1957). Studies on the culture of a marine diatom, J.Mar, Biol.

Ass.U.K.33:265-290.

Strickland, J.D.H., and parsons, T.R., (1977). A practical hand book of

seawater analysis, Bull No.125. Fisheries Research Board, Canada,

Ottawa.

117

Stumn, W., (1992) Chemistry of solid water interphase Willey, New York. 428

pp.

Sughandhini Naik and Sen Gupta, R, (1981). Studies on Calcium, Magnesium

and Sulphates in the Mandovi and Zuari River systems (Goa) I.J.M.S.

10 : 24-34

Sverdrup, W.H. and Seibert, D. L.R., (1977), Effects of Copper on the

dominance and the diversity of algae: Controlled ecosystem pollution

experiment . Bull. Mar. Sci 27 : 23-33.

Tang, D., Warnken, K.W., Santschi, P.H., (2002) Distribution and partitioning

of trace metals ( Cd, Cu, Ni, Pb, Zn) in Galveston Bay waters, Marine

Chemistry. 78 : 29-45

Thomas, W.H., and Seibert, D.L.R., (1977), Effects of Copper on the

dominance and the diversity of algae : Controlled ecosystem pollution

experiment. Bull Mar. Sci, 27-33

Turekian, K.K., (1977). The fate of metals in the oceans Geochim Cosmochim

Acta, 41 : 1139 –m 1144

Turekian, K.K., (1969). The oceans, streams and atmosphere . In : Handbook of

Geochemistry, pp . 297 – 323

Turener, D.R., Sirinawin, W., Wester land, S., (2000), Cr (VI) distributions in

the Arctic and the Atlantic Oceans and reassessment of the oceanic Cr

cycle Marine Chemistry. 71., 265-282

Van den Berg, C.M.G., Merks, A.G.A, and Dursma, K.E, (1987) Organic

complexation and its control of the dissolved concentrations of Copper

and Zinc in the Scheldt estuary Estuar Coast Shelf Sci, 24

Voelker, B.M. Kogut, M.B. (2001) Interpretation of metal speciation data in

Coastal waters. Effect of humic substances on Copper binding Mar

Chem, 74 (4) pp. 303 -318

118

Vuceta, J., and Morgan, J.J., (1978). Chemical modelling of trace metals in

fresh water Envir Sci Tech 12: 1302 – 1307.

Wedepohl, K. H., (1972), Zinc-abundance in natural waters and in the

atmosphere, In : Wedepohl, K.H. (ed) Handbook of Geochemistry,

Berlin

Windom, H.L., Beck, K.C. and Smith, R., (1971) Transport of trace metals to

the Atlantic Ocean by three southern rivers. South East, Geol, 12 : 169 –

181

Wittmann, G.T.W., (1983). Toxic metals , In : Forstner , U. and Witmann

G.T.W (eds) Metal Pollution in the Aquatic environment, Springer –

Verlag Berlin pp 3- 68.