COMPARISON OF HEAVY METAL PATTERN BETWEEN WATER AND SEDIMENTS

IN PASIG RIVER SYSTEM, PHILIPPINES

Teodinis P. Garcia*, Assistant Professor, Technological University of the Philippines Taro Urase, Associate Professor, Tokyo Institute of Technology Yosuke Suzuki, Master Course Student, Tokyo Institute of Technology *: Stay in Japan from 27 February 2003 to 27 May 2003 funded by the JSPS core university program

ABSTRACT Water samples from Pasig river and from its branches were collected and chemically analyzed using the inductively coupled plasma mass spectrometry (ICP-MS) and the inductively coupled plasma atomic emission spectrometry (ICP-AES) to quantify heavy metal concentrations. The study aimed to clarify the heavy metal pollution of this region focusing on the effect of urban water discharge on sediment quality of Pasig River. The survey was conducted during the dry season and slight salt intrusion from Manila Bay to the river system was observed. The concentrations of copper, zinc, lead, titanium and iron were quantified. Furthermore, the results showed that higher particulate lead concentration of water is observed from the sample taken at San Juan River. These results suggest that there is a route of lead discharged from urban area and transported via San Juan River to Pasig River then to Manila Bay. INTRODUCTION Pasig River in the Philippines is the main waterway flowing through Metro Manila between Laguna de Bay and Manila Bay. The Pasig river system includes the Pasig, San Juan and Marikina rivers in greater Manila. The Pasig river system is heavily polluted with industrial, municipal and domestic wastes. Rehabilitation works for the Pasig River is on going. The long term goal of the Philippine Government is to upgrade the water quality of Pasig River to sustain aquatic life, spur tourism growth and establish new transportation routes. A comprehensive study into the pollution of the Pasig River, Marikina River and San Juan River by metals and organic pollutants as a result of polluting industrial practices urban run-off is deemed necessary. Most of the pollution studies which assessed the health of the river mainly focuse on organic pollution which can be evaluated by the index of biological oxygen demand (BOD) and dissolved oxygen (DO). Because BOD only accounts for decaying organic matter, it tells us little about the presence and effects of persistent toxins including metals (metals do not degrade in the environment) and long-lived organic poisons.

This study focuses on the determination of the concentration of heavy metals in Pasig River system. The result of this study will provide baseline data on heavy metal concentration in

water samples of the aforementioned river system and thus aid in the effectiveness of pollution control strategies. MATERIALS and METHOD Study site and sampling Raw water samples were taken from the Laguna Lake, Pasig River, Marikina River and San Juan River of the Philippines. Sampling locations are indicated as shown in Table 1. Sampling point LL refers to Laguna Lake; location 1 is middle stream of Pasig River, between the mouth of Laguna Lake and the merging point with Marikina River. Location 2 refers to Marikina River, while sampling point 3 is the San Juan River, which is heavily polluted by domestic and industrial wastewater. Sampling site 4 is the down stream of Pasig River, near Manila bay. Water sample from Laguna Lake was collected by Prof. Nadaoka’s laboratory members and water samples from the four locations were collected in February, 2003 by Prof. Urase and Mr. Suzuki. The data used for the concentration of bottom sediments were obtained from a previous study of T. Urase, et al (2002). The sampling sites considered for the sediment samples are those that roughly coincide with the points of sampling for water samples. Table 1 Description of sampling locations

Water Description LL Laguna Lake 1 Pasig River, Bridge of Dr. Sixto Antonio Avenue 2 Marikina River, Bridge of Pasig Boulevard 3 San Juan River, Bridge of Shaw Boulevard 4 Pasig River, Nagtahan Bridge

Analytical Techniques Preparation of samples for chemical analysis The raw water samples were divided and fractionated into total fraction and dissolved fraction. Dissolved fraction samples were prepared by filtration using GFC filters. Nitric acid is added to the raw samples and dissolved fraction samples in order to preserve the metal and to avoid precipitation. Digestion of Sample There is a need for proper preparation of the materials to be used for digestion of samples. As much as possible eliminate contamination of the sample to be analyzed since it will affect the result. The laboratory wares were soaked in nitric acid bath and were rinsed thoroughly using pure water to avoid contamination of metal. The materials used were glass beaker (100ml), glass cover, mess flask (50 ml & 100 ml), plastic bottles for the sample. Likewise clean the working area to minimize possible contamination. Digestion of sample is carried out to reduce interference by organic matter and to convert metals associated with particulates to form (usually the free metal) that can be determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The total number of samples digested was twelve (12), five water samples for each

category and two blanks (pure water). The blanks were pure water as old as the water samples (may contain some degree of contamination) and pure water taken from the de-ionized machine during the performance of the digestion process. One hundred (100) ml of water sample were placed in a glass beaker, and then 1 ml of nitric acid was added. It was then heated for two hours using a hot plate. When the digested sample has cooled down, it was filtered using Whatman GF/C 47 mmφ filter. The filter was pre-rinse with nitric acid to ensure minimization of contamination. After filtration, the sample was transferred to a mess flask in which 100 µl of internal standard solution was added. Bismuth (Bi) and Ytrium (Y) were used as internal standards. It was then diluted with pure water to make up 100 ml and transferred to the plastic bottle for analysis.

ICP Analysis

Chemical analysis of the samples is done using the Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). These analytical methods are used for the detection and quantification of desired metal species present in the sample. For elements with low concentration, ICP-MS is used since it provides greater sensitivity compared to ICP-AES. Likewise for elements with high concentration, ICP-AES is more suitable to use because it may not be affected by mass-spectral interference. Target Elements

There are ten (10) target elements to be quantified using the above mentioned analytical methods. These are the following elements: copper, nickel, zinc, cadmium, cobalt, lead, chromium, manganese, titanium, and iron. General Water Quality The anion concentration was determined using the Ion Chromatography (HITACHI G-7000 series). The cations like Na, K, Ca, Mg, Sr, Ba were measured as metal by ICP/AES. Suspended solid concentrations were measured by using GF/C filters. DISCUSSION AND ANALYSIS OF RESULTS General Water Quality Measurement of Suspended Solids The result of measurement of suspended solids (SS) is tabulated in Table 2. The measurement was done twice and the average concentration is computed as shown in the table. It can be noted that suspended solids (SS) in sample 1 and 4 (Pasig river) yields almost the same quantity. The suspended solids in the Laguna Lake are relatively high compared to other sampling sites. Sample location 3 gives the lowest value. Consequently, the main source of the suspended solids in the Pasig river is not the urbanized wastewater but the Laguna Lake.

Table 2. Suspended Solids Measurement

Sample Trial 1 (mg/l) Trial 2 (mg/l) Ave (mg/l) 1 78.4 86 82.2 2 32.8 36.4 34.6 3 21.2 22.8 22 4 84.4 81.2 82.8

LL 103.2 109.2 106.2 Blank -4 -3.2 -3.6

Anion concentration The summary of results using the ion chromatography machine is shown in Figure 1. The obtained concentrations were corrected by standard concentration of the ions being considered and by dilution factor. Figure 1 shows the concentration of the anions Cl-, SO4

2-, NO3- in each sampling

points. Take note that the unit of the concentration of elements for the sample from Manila bay is in g/l, while the rest is in mg/l.

Figure 1. Anion concentration

Raw water sample from Manila bay was also analyzed aside from the five samples. The chloride and sulfate concentrations of Manila bay is very high. There is only a slight difference in concentration of Cl- and SO4

2- from the mouth of Laguna Lake to the stretch of Pasig River. The concentration of Cl- and SO4

2- in Marikina and San Juan rivers were lower than that of the Pasig river. The presence of NO3

- is observed in sample locations 1, 2, and 3. Concentration of NO3- is

considerably higher in San Juan River (point 3) than in the other sampling locations. Nitrification from ammonium to nitrate may have taken place during storage or transportation of the samples. It can be observed that water sample from Manila Bay has almost 20,000 mg/l of chloride; this means that the sample is seawater. Judging from the measurement in September, 2002, complete freshwater in this Pasig river area is around 30 mg/l for chloride concentration. Actually, the February, 2003 survey shows that chloride concentration for sampling points 2 and 3 is about 30 mg/l. This value indicates that water sample in points 2 and 3 are complete freshwater. Whereas the chloride concentration in samples 1, 4, and LL is about 200 mg/l, this means that there is a slight intrusion of seawater in these sampling points. Further observation denotes that in the Philippines, September is wet season and February is part of the dry season. Based on the two measurements, it can be deduced that there is a slight seawater intrusion in Pasig River in the dry season. Cation and Metal Concentration using ICP-AES Table 3 shows the summary of cation and metal concentration present in the water samples. For comparison, measurement conducted in 2002 September for the Pasig river sample was added as reference P2. The cations analyzed were Na, Mg, K, Ca, Sr, and Ba. It is observed that the concentration of Na is higher than that in the previous survey due to salt intrusion in the dry season.

0.00

50.00

100.00

150.00

200.00

Cl- SO4-2

Con

cent

ratio

n(m

g/l)

raw MB

rawLL

raw 1

raw 2

raw 3

raw 4

19.9 g/l

2.50 g/l

0.00

50.00

100.00

150.00

200.00

Cl- SO4-2

Con

cent

ratio

n(m

g/l)

raw MB

rawLL

raw 1

raw 2

raw 3

raw 4

19.9 g/l

2.50 g/l

Table 3. The concentration of cations. Dissolved fractions were subjected to analysis for ICP/AES (All units are mg/l).

Sample ID Na Mg K Ca Sr Ba LL 82 21 1.9 14 0.19 0.07 1 75 21 1.9 14 0.20 0.08 2 33 12 1.1 33 0.27 0.06 3 35 7.7 1.2 32 0.20 0.09 4 67 19 1.8 17 0.20 0.06

Ref. P2 28 8.4 5.4 14 0.12 0.02 Heavy Metal Concentration There are ten (10) elements analyzed in the water samples from Pasig River, Marikina River, San Juan River, and Laguna Lake. These elements are Cu, Ni, Zn, Cd, Co, Pb, Cr, Mn, Ti, and Fe. All the samples including total fractions and dissolved fractions were analyzed both by ICP-AES and ICP/MS. The repeated measurements were conducted for Mn, Ti, and Fe with increased maximum quantified concentration because their concentrations were too high to be quantified. Table 4 shows the detection methods for target elements and reason for the selection of the method. Table 4. Selection of detection methods for target elements. Element Method Reason of the selection of the method Cu ICP/MS

(m/z)=65 Concentration was too low for ICP/AES Slight interference by NaAr on 63Cu. 65Cu was selected.

Ni not determined

Concentration was too low for ICP/AES. Due to interference neither 60Ni nor 62Ni can be used.

Zn ICP/MS (m/z)=68

Slight difference between 66Zn nor 68Zn was observed. ICP/AES can also be used but sometimes higher sensitivity was required. The use of 68Zn is recommended by Japan sewer works association.

Cd not determined

Concentration was too low both for ICP/AES and ICP/MS.

Co not determined

Concentration was too low both for ICP/AES and ICP/MS.

Pb ICP/MS (m/z)=208

Concentration was too low for ICP/AES Larger counts can be obtained for 208Pb than for 206Pb.

Cr not determined

Concentration was too low both for ICP/AES. Severe interference on 53Cr. There is inconsistency between ICP/AES and ICP/MS (m/z=52)

Mn ICP/AES ICP/AES and ICP/MS(m/z=55) gives consistent results. ICP/AES was used due to its linearity in the higher concentration measurement.

Ti ICP/AES ICP/MS did not give appropriate results. Fe ICP/AES ICP/MS did not give appropriate results.

Table 5 summarizes the metal concentration of the samples. Figure 2 shows the graphical representation of the comparison between the total and dissolved metal fraction of lead. Lead is considered as a good indicator of pollution by urban run-off. Its presence in higher concentration in sample 3 as shown in the figure 2 suggests that there is a route of lead discharge from San Juan river and transported via Pasig river then to Manila bay. In sample 3, which is the San Juan river, it can be seen in the table that there is a higher concentration of Mn in the dissolved form. In the case of zinc, higher concentration of dissolved fractions compared to those of total fractions was observed. This might be related to problems in chemical analysis.

Table 5. Summary concentration of elements considered for further analysis. (µg/l)

LL-T 1-T 2-T 3-T 4-T LL-D 1-D 2-D 3-D 4-D Cu 10 13 4.4 6.6 6.5 2.7 5.1 2.2 3.4 2.8 Zn 11 19 13 33 13 18 29 24 47 16 Pb 2.5 3.9 1.6 6.3 2.4 0.53 1.0 0.39 1.9 0.54 Mn 130 83 490 380 110 5.0 5.8 450 400 35 Ti 210 130 8.8 9.7 91 16 24 0.24 0.43 17 Fe 3100 2800 810 850 2000 230 400 260 320 280

Figure 2. Concentration of dissolved and total lead in the samples. Comparison of Particulate Metal Concentration in Unit Weight of Suspended Solids in Water Sample to Metal Concentration of Bottom Sediments Sample The result of the analysis of the water samples was compared to the bottom sediments analysis. The concentration of particulate metal which is the total concentration subtracted by dissolved concentration was calculated as metal weight based on unit suspended solids and was compared to the concentration of sediments corresponding to the sampling points of water sample. The summary of results for the particulate metal concentration in water and sediments are shown in Tables 6 and 7 respectively. In the case of copper, titanium and iron, it can be observed that the metal concentration in sediments is higher than in the water sample in all the sampling points. Lead concentration is highest in sample location 3 (San Juan river). It can also be noted that the lead concentration in sample 1 and 3 gives higher value in water than in the sediments. Higher particulate lead concentration of water in sample 3 indicates that run-off from the vicinity of San Juan river is a source of lead in water and transported to Manila Bay through the Pasig river.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

LL 1 2 3 4

Sample location

Con

cent

ratio

n(ug

/l)

Pb: Total fraction Pb: Dissolved fraction

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

LL 1 2 3 4

Sample location

Con

cent

ratio

n(ug

/l)

Pb: Total fraction Pb: Dissolved fraction

Table 6. Summary of particulate metal concentration in unit weight of suspended solids

Element Cu Pb Mn Ti Fe SS

Sample mg/kg mg/kg g/kg g/kg g/kg mg/l LL 70.24 18.64 1.135 1.80 27.32 82.20 1 61.50 34.92 0.938 1.31 29.73 34.60 2 65.09 34.393 0.968 0.25 15.85 22.00 3 143.68 199.09 -0.634 0.42 24.20 82.80 4 44.59 22.22 0.74 0.90 20.99 106.20

Table 7. Summary of metal concentration of sediment samples

Element Cu Pb Mn Ti Fe Sample mg/kg mg/kg g/kg g/kg g/kg

L1 116 21 1.2 3 58 P4 76 18 0.8 3 56 M1 128 23 0.8 3 63 S1 114 88 0.9 3 57 P2 114 51 0.9 2 58

CONCLUSION Water samples from Pasig river and from its branches were collected and chemically analyzed using the inductively coupled plasma mass spectrometry (ICP-MS) and the inductively coupled plasma atomic emission spectrometry (ICP-AES) to quantify heavy metal concentrations. The study aimed to clarify the heavy metal pollution of this region focusing on the effect of urban water discharge on sediment quality of Pasig River. The survey was conducted during the dry season and slight salt intrusion from Manila Bay to the river system was observed. The concentrations of copper, zinc, lead, titanium and iron were quantified. Furthermore, the results showed that higher particulate lead concentration of water is observed from the sample taken at San Juan River. According to Y. Suzuki and F. Siringan’s survey, spatial distribution of concentration of lead in sediments shows diffusion pattern from the mouth of Pasig river. These results suggest that there is a route of lead discharged from urban area and transported via San Juan River to Pasig River then to Manila Bay, though further analysis and discussion is necessary to obtain clearer conclusion. Acknowledgement

This research is a subtopic of the Integrated-Manila Bay-Laguna Lake and Surrounding Watersheds Environmental Study (IMSWES) headed by Prof. Kazuo Nadaoka, who is responsible for the management of Group 1 of the JSPS core university program on environmental engineering between Tokyo Institute of Technology and the University of the Philippines.