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IMPACTS OF HEAVY METALS FROM INDUSTRIAL WASTES ON SOIL

FAUNA

BY:SOLANKE, ABIMBOLA AJIBOLA

129077030

DATE: 11/06/2013

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OUTLINE

INTRODUCTION

INDUSTRIAL WASTES AND COMPONENTS

HEAVY METAL AS A TOXICANT

SOIL FAUNA: BIODIVERSITY

- Soil fauna and types

- Importance of soil biodiversity

IMPACTS OF HEAVY METALS ON SOIL FAUNA

CASE STUDY

RECOMMENDATIONS AND CONCLUSION

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INTRODUCTION

• Industrial revolution in the 17th century led to a better standard of

living, which in turn resulted in explosion of human population.

• Although, Industrialization helped to generate employment, create

different sources of income, and increase the overall well-being of

this growing populace.

• However, its activities and processes often leave a very harmful

effect on the environment, which is usually ignored especially in

developing countries (Scott, 1998).

INTRODUCTION

• Industrial wastes contain harmful substances like acids,

heavy metals, which have hazardous effects on the

physical environment, like the soil, hence affecting the

soil organisms alike.

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INDUSTRIAL WASTES• Industrialization is the process of mechanical, physical and

chemical transformation of raw materials into new forms so that

they serve new ends and satisfy new requirements (Akhimien et

al., 2012).

• Industrial wastes are the by-products produced during industrial

activities, such as that of factories, mills and mines.

• These wastes, treated or not, are disposed into the environment.

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INDUSTRIAL WASTES (cont’d)

• The final disposal of potentially toxic residues in the soil has

become a practical and inexpensive alternative and can cause

alterations in the arthropod community (Van, 2004).

• They can be broadly categorized into:

– Effluent: discharge of liquid wastes, usually into water bodies

– Gaseous wastes

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FORMS OF INDUSTRIAL WASTES

Plate 1a: discharge of industrial effluents into the environmentSource: depositphotos.com.

Plate 1b: smoke stack from chimneysSource: http://blog.airdye.com

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MAJOR CONSTITUENTS OF INDUSTRIAL WASTES

• Oxides of Nitrogen (NOx)

• Oxides of Sulphur (SOx)

• Oxides of Carbon (CO and CO2)• Dust/particulates• Volatile organic compounds (VOCs)• Acid gases• Heavy metals• Organic micro-pollutants (e.g. polychlorinated

biphenyl, polyhydrocarbons).

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INDUSTRIAL WASTES (cont’d)

Plate 2: Industrial and Commercial Wastes Survey in UK in 2002/2003.Source: archive.defra.gov.uk

HEAVY METAL AS A TOXICANT

• Heavy metals are metallic elements with specific gravity higher

than 5.00 and are toxic and poisonous even at low

concentration (Duruibe et al., 2007; Lenntech, 2004).

• Some, like Zinc and Iodine, are needed in trace quantities in the

body.

• They are persistent environmental contaminants, undergo

speciation, and are bioavailable (Wuana and Okieimen, 2008).10

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HEAVY METAL AS A TOXICANT (cont’d)

• Although these elements are lacking in abundance they

are not lacking in significance (Chen and Chen, 2001)

• Toxicities of heavy metals can range from severe illness

to death of both plants and animals (Galadima and

Garba, 2012).

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Table 1: Examples of heavy metals and their specific gravity

Name Symbol Specific Gravity

Arsenic As 5.7

Cadmium Cd 8.65

Iron Fe 7.9

Lead Pb 11.34

Mercury Hg 13.546

Source: Galadima and Garba, 2012.

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SOURCES OF HEAVY METALS

• Natural sources: Heavy metals occur naturally in the soil

environment, which are rarely toxic (Kabata-Pendias and

Pendias, 2001).

• Anthropogenic sources: Due to the disturbance and

acceleration of nature’s slowly occurring geochemical cycle

of metals by man.

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SOURCES OF HEAVY METALS (cont’d)

• Anthropogenic emission into the atmosphere, for several

heavy metals, is one-to-three orders of magnitude higher

than natural fluxes (Sposito and Page, 1984).

• Heavy metals in the soil from anthropogenic sources tend

to be more mobile, hence bioavailable than pedogenic or

lithogenic ones (Kaasalainen and Yli-Halla, 2003).

HEAVY METALS IN SOILS• Soils may become contaminated by the accumulation of heavy

metals and metalloids through emissions from the– rapidly expanding industrial areas, – mine tailings, – disposal of high metal wastes, – leaded gasoline and paints, – land application of fertilizers, – animal manures, – sewage sludge, – pesticides,– wastewater irrigation, – coal combustion residues, – spillage of petrochemicals, and – atmospheric deposition (Khan et al., 2008)

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SOIL FAUNA

• Soil biodiversity is comprised of the organisms that spend all or a

portion of their life cycles within the soil or on its immediate surface

(including surface litter and decaying logs).

• Soil is the most abundant ecosystem on earth, however the vast

majority of the organisms in the soil are microbes, a great number of

which are yet to be described (Amber, 2008).

• Roesch et al. (2007) suggested that there are over a million species

per gram of soil, although a later study suggests a maximum of just

over 50, 000 species per gram of soil.

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SOIL FAUNA (cont’d)• The level of abundance and diversity vary from soil to soil,

depending on some factors such as:

– Soil organic matter content,

– Soil pH,

– Soil texture, and

– Soil management (Gardi and Jeffery, 2009).

• In healthy soils, invertebrates are very abundant and thrive with

minimal maintenance, adequate food supply and habitat

requirements.

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TYPES OF SOIL FAUNA

• There are three classes of soil fauna, on the basis of size (Gardi

and Jeffery, 2009). These are:

– Micro-fauna (1µm – 100µm) e.g. protozoa, nematodes

– Meso-fauna (100µm – 2mm) e.g. mites, diptera (fly) larvae

– Macro-fauna (2mm – 20cm) e.g. termites, earthworms

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SOIL FAUNA

Plate 3: types of soil fauna according to sizeSource: Turbe et al., 2010.

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Plate 4: Meloidogyne incognita (root knot nematode)– a microfauna

Source: wikipedia.

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Plate 5: Orchesella cinta (Springtail) - mesofaunaSource: wikipedia

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Plate 6: Lumbricus terrestris – a MacrofaunaSoure: www.soil-environment.blogspot.comsearchlabelheavy%20metals

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IMPORTANCE OF SOIL FAUNA

• According to Turbe et al. (2010), importance of soil

fauna can be summarized as follows:

– Improvement of soil structure and fertility

– Regulation of carbon flux and climate control

– Regulation the of water cycle

– Decontamination and bioremediation

– Human health

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IMPORTANCE OF SOIL FAUNA (cont’d)

PLATE 7: An earthworm gallery filled with casts and a rootSOURCE: Ruiz et al., 2008.

Root using anearthworm galleryto penetrate into soil

Granular castsproduced by earthworms that feedon dejections

A part of the gallery isfilled with earthwormexcrement

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IMPACTS OF HEAVY METALS ON SOIL FAUNA

• Pollution by heavy metals is a serious environmental

concern, due to their non-biodegradability and tendency

to accumulate in plants and animal tissues (Otitoloju et al.,

2009).

• The impacts of heavy metals on soil fauna:

– Results in bioaccumulation.

– Alters the abiotic environment such as temperature and

humidity.

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DETRIMENTAL EFFECTS

– Decrease in the diversity of species (Del Val et al., 1999; Syrek et al., 2006; Beyrem et al., 2007).

– Reduction in microbial biomass activity

– Introduction of invasive species (r-strategists)

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DETRIMENTAL EFFECTS CONT’D– Reduction in enzymes activities (Abdolkarim et al.,

2009)

– Heavy metals affect their ecological function (Smith

et al., 2005).

– Shortens the food chain (reduction in energy

budget).

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DETRIMENTAL EFFECTS CONT’D

– Increase in abundance of species (invasive

species).

• There was abundance of Protura, Diplura and

Collembola with increase in the pollution by metals

(Migliorini et al. , 2004).

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CASE STUDY Dynamics of soil nematodes and earthworms in urban vegetable

irrigated with wastewater in the Nairobi River-Basin, Kenya, by Karanja et al., 2010.

• The effects of heavy metals lead (Pb), Cadmium (Cd) and

Chromium (Cr) on nematode communities and earthworm

density and biomass were studied in the wastewater irrigated

farms of the Nairobi River Basin (Kibera and Maili-Saba farms).

• The soil samples and effluent were tested for Pb, Cd, and Cr

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CASE STUDY (cont’d)

• Monolith sampling for earthworms was done using

the procedures described by Moreira et al. (2008)

• Nematodes were examined using modified

Baermann’s procedure described by Hooper et al.

(2005)

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CASE STUDY (cont’d)• TABLE 2: Heavy metal accumulation in soils in the Kibera and

Mali-Saba farms

Source: Karanja et al., 2010.MPL*: Maximum Permissible Limits (WHO, 2006).

KIBERA MAILI-SABA WHO MPL*

Chromium (Cr)

9.7(mg/kg) 4.0(mg/kg) N/A

Lead (Pb) 1.7(mg/kg) 74.3(mg/kg) 84 (mg/kg)

Cadmium (Cd)

14.3(mg/kg) 98.7(mg/kg) 4.0 (mg/kg)

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CASE STUDY (cont’d)

• Table 3: Plant feeding nematode genera and trophic groups associated with wastewater in Kibera and Maili Saba

* Significant difference between pairs at P<0.05 Source: Karanja et al., 2010.

PLANT FEEDING NEMATODES /200cm3soil MAILI-SABA KIBERAPratylenchus 17 30* Paratylenchus 10 15

Meloidogyne 26 20Scutellonema 18* 11Criconema 11* 5Helicotylenchus 0* 15

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CASE STUDY (cont’d)Table 4: Bacteria feeding nematode genera and trophic groups associated with wastewater in Kibera and Maili Saba.

* Significant difference between pairs at P<0.05 Source: Karanja et al., 2010.

Bacteria FEEDING NEMATODES /200cm3soil

MAILI-SABA KIBERA

Alaimus 45* 35

Rhabditis 86* 70

Acrobeles 35 45*

Cephalobus 48* 35

CASE STUDY (cont’d)

Figure 1: Earthworm abundance and biomass in wastewater treated plotsSource: Karanja et al., 2010.

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CASE STUDY (cont’d): DISCUSSION

• High heavy metal concentration as well as organic

matter were negatively correlated with the plant feeding

nematodes (Table 3).

– Ekshmitt and Korthals (2006) obtained similar result.

• Bacteria feeding nematodes were predominant in the

gardens treated with heavy metals (57% of all

nematodes found) (Table 4). 35

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CASE STUDY (cont’d): DISCUSSION

• An average density of 198 m-2 of earthworms and a biomass

of 68 gm-2 were found in Kibera;

• An average density of 102 m-2 of earthworms and a biomass

of 33 gm-2 were found in Maili-Saba (Figure 1).

• The earthworms isolated from both sites were epigeic with

the metal content in Maili-Sapa suppressing their population

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CASE STUDY (cont’d): CONCLUSION

• High heavy metal concentration affects the population

of plant feeding nematodes, but enhances the

population of bacteria feeding nematodes.

• Amongst the heavy metals under this investigation, Cd is

known to be the most toxic (Vandescateele, 2004) while

Cr and Pb may not significantly affect earthworm

activities and growth according to Kumar et al., (2008).

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RECOMMENDATION• Pretreatment of industrial discharges from sewage using

efficient Effluent Treatment Plants (ETP).

• Enforcement of existing environmental guidelines.

• Frequent review of maximum permissible limits of heavy metals.

• Regular inspection of industrial wastes, treated or not, that are being discharged into the environment.

• Remediation of impacted soils/environment.

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CONCLUSION

• Soil fauna are very significant in the proper functioning of

an ecosystem.

• Man is the greatest threat to their existence, and we need

them more than they need us.

• Thus, it is imperative that we stop/reduce heavy metal

pollution to ensure their survival, our survival.

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THANK YOU FOR LISTENING