Metal Geochemistry of Nerus River,Terengganu
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The Malaysian Journal of Analytical Sciences, Vol 12, N0 3 (2008): 593 - 599 METAL GEOCHEMISTRY OF NERUS RIVER,TERENGGANU . Poh Seng Chee 1*, Suhaimi Suratman 1, Chew Choon Keat 1, Noor Azhar Mohamed Shazili 2 and Norhayati Mohd Tahir 1. 1Environmental Research Group (ERG)/ Department of Chemical Sciences, Faculty Science and Technology 2Institute of Oceanography, University Malaysia Terengganu, Mengabang Telipot, 21030 Kuala Terengganu, Terengganu *Corresponded author: [email protected] Abstract The Nerus River passes through the Setiu and Kuala Terengganu districts, on the east coast of Peninsular Malaysia. It passes through the populated urban area of northeastern Kuala Terengganu and receives and carries different kinds of agricultural and urban solid and liquid wastes produces by agricultural based industries and domestic sewage. The objective of this study is to investigate trace metal concentration in suspended particulate and water of the Nerus River and relate this to the anthropogenic activities. Water samples were collected from nine sites during dry and pre monsoon seasons (from May to October). Water pH, temperature, electric conductivity and salinity were measured in-situ. The suspended particulate was separated from water by using 0.45 µm pore size acetate cellulose membrane filter. Water (filtered) samples were subjected to APDC-MIBK pre-concentration and particulate samples were totally digested by using strong acids. Cd, Cu, Zn and Pb were analyzed using GFAAS and ICP-OES. Although the overall concentration of the metals obtained were still within Class I limit of the INWQS, however the results indicated that there is an increasing trend of Cu and Zn concentration in Nerus River water compared to previous study done in 2001. High Cu and Zn concentration in suspended matter sampled at downstream station which received effluent from nearby factories. Keywords: urban river, dissolved metals, particulate metals Introduction The changes in quality and quantity of river water resources are accelerating due ever increasing human- induced pollution and shift in land use. Population and economic growth continue to increase the demand on clean water; hence protecting high quality water resources has become local authorities’ foremost concern. It is well known that, river pollution is most commonly associated with the discharge of effluents from the sewers, drains or factories (Yuce et al. , 2006). Apart from point sources, diffuse sources such a storm water and agricultural runoff and atmospheric fallout also significantly contributed to water pollution. Off the list of the river pollutants, heavy metals continue to be one of the most frequently occurring and toxic group of contamination. Their compounds are not subjected to destruction in the water body. Furthermore, the ability of some organism to accumulate heavy metals in their tissues would potentially lead to movement of these metals to higher tropic in the food chain (Chapman, 1997). The present study, carried out at the Nerus river basin, is aimed at compiling the spatial and temporal trends of heavy metals concentration in both dissolved and particulate forms in their river system. This work forms part of the long term water quality project for main river basins in Terengganu carried out by UMT researchers since 1999. Methods and Materials Sampling sites The Nerus River passes through the Setiu and Kuala Terengganu district, east coast of Peninsular Malaysia. The river basin extends about 77km and stretches between latitude 103º00’ E to 103º06’E and longitude of 05º13’N to 05º23’N. Its catchments area totals 851 km 2. Its source is at Gunung Sarut and flows southeastern in towards the mouth of Nerus River which discharges its water into Terengganu River estuary before finally discharging into the South China Sea. Nerus River basin comprises of tributaries namely Tepuh River, Pelung River, Telemong River, Las River, Tong River, Linggi River, Tayur River, Temiang River and Semelang River (Shazili et al ., 2004). The river flows through villages, farms and palm oil factories. It also passes through the populated urban area of northeastern Kuala Terengganu and receives and carries different kinds of agricultural and urban solid and liquid wastes produces by agricultural based industries and domestic sewage. 593 Poh Seng Chee et al: METAL GEOCHEMISTRY OF NERUS RIVER,TERENGGANU. Sampling procedure Water samples were collected in polyethylene bottles from nine stations along the waterway (Figure 1). All sampling bottles were cleaned using detergent followed by soaking in diluted nitric acid for one week and finally thoroughly rinsed with double deioned water. A total of 5 sampling trips were carried out at each sampling stations, between May to October 2004. pH, salinity and electrical conductivity were measured in-situ with YSI Multiparameter Hydrolab. During water sampling, the pre-cleaned sampling bottle was first rinsed with the river water before collecting the actual sample. Upon collection, samples were temporarily stored in an ice cooled container and transported back to the laboratory for further chemical analysis. Fig. 1: Location of sampling sites in Nerus River. Samples preparation and analysis Total suspended solid was analyzed by filtering a know volume of water through a pre-weighed 0.45 µm pore size Milipore filter paper and the resultant filter paper dried at 105ºC till constant weight (APHA, 1992). Samples were vacuum-filtered through 0.45 µm Millipore filter paper in a class 100 laminar flow hood. Both filter papers and filtrates were retained for particulate and dissolved metals analysis respectively. For particulate metals, the filtered suspended particulates were digested with a mixture of HNO 3-HCl-HF acids (4:3:2 ml ratio) in a microwave digestion system (Ethos Plus, Milistone) at 210ºC for 30 min. Excess HF in samples were neutralized using 10 ml of saturated H 3BO 3 (Hussain et al. 2002 and Pruseth et al., 2005). For dissolved metals, the filtrate samples were preconcentrated and the matrix removed from water using APDC-MIBK solvent extraction method. A 200ml aliquot of the sample was placed in a 250ml teflon separatory funnel and the pH adjusted to 3-3.5 with ammonia solution and nitric acid. Then, 5ml of 1% (w/v) APDC (ammonium pyrrolidine dithiocarbamate) was then added, shaken for 1 min and left to settle for 2 min. 594 The Malaysian Journal of Analytical Sciences, Vol 12, N0 3 (2008): 593 - 599 Later, 6 ml of MIBK (methyl isobutylketone) was added, the separatory funnel shaken for 1 min and the aqueous and solvent layers left to separate for 2 min. The aqueous layer was then transferred to another separatory funnel and the extraction procedure repeated. The aqueous layer was discarded and the MIBK layers from the first and second extractions were then combined. Trace metals were back-extracted into 5ml 2M HNO 3 by shaking the acid with the MIBK for 30 s and the acid layer collected after 2 min of standing. This method provided a 40-fold preconcentration factor. Additionally, to check the accuracy efficiency of the extraction method, standard solutions with known concentrations were analyzed. In general, recoveries for Cd were 84.7 ± 0.87%, Cu 101.2 ± 0.38%, Pb 82.6 ± 1.17% and Zn 80.3 ± 0.51%. Cd, Cu, Zn and Pb in the acid extracts were analyzed by inductively coupled plasma optical emission spectroscopy (Vista Pro, Varian).The Vista Pro features a custom designed charge coupled device (CCD) detector, which provided true simultaneous measurement and full wavelength coverage from 167 to 785 nm. The CCD detector contains continuous angled arrays that are matched exactly to the two-dimensional image from the echelle optics (Calderon, 2000). These features allowed both trace and major levels analytes to be measurement in the same measurement. The radio-frequency (RF) robustness of the instrument also permits the analysis of difficulty samples up to 5% total dissolved solids, using axially viewed plasma (Bridger and Knowles, 2000). The instrument also equipped with a concentric glass nebulizer and a glass cyclonic spray chamber and the entire system was controlled by ICP Expert software (Varian, Australia). The practical limit of detection for Cd, Cu, Pb and Zn were 0.5µgL -1, 0.06 µgL -1, 0.6 µgL -1 and 0.6 µgL -1 representatively. Results and Discussion Table 1 presents the results obtained for dissolved and particulate metals analyzed in this study. Selected physical parameter measurements were also included in the table. Figure 2 and Figure 3 shows the spatial and temporal distribution of metals for the nine sampling stations respectively. The concentrations for dissolved fractions were in the range of 0.03-1.14 µgL -1 Cd, 0.23-1.59 µgL -1 Pb and 1.54-21 µgL -1 Zn. The levels for particulate Cd, Pb, Cu and Zn varied from 0.23 to 0.97 µgL -1 , 0.15 to1.85 µgL -1 , 0.53 to 5.29 µgL -1 and 0.84 to 12.5 µgL -1 respectively. Generally, higher concentrations of Cd in particulate form compared to dissolved form were observed in Nerus River. Similarly for Cu, with exception of S1 and S6, particulate Cu is the dominant species in Nerus River. Zn on the other hand showed the reverse trend, where higher Zn concentration in the dissolved forms was found in all stations compared to the particulate form. In the case of Pb and Cu, no obvious trend could be seen between dissolved and particulate forms, some sampling sites like S1, S3 and S9 showed high contents of Pb in particulate forms whereas the remaining sites showed opposite trends. Table 1. Statistical results of pH, salinity, electric conductivity and metals concentrations in water of the Nerus River. Parameter Mean Median Std.Dev. Minimum Maximum pH 5.49 5.38 0.36 4.55 6.44 Salinity 0.10 0.01 0.38 0.01 1.99 EC (mV) 69.0 72.0 21.0 16.8 123 TSS (mg/L) 18.8 12.8 23.4 0.33 140 Dissolve form ( µgL -1) Cd 0.06 0.06 0.02 0.03 0.14 Pb 0.87 0.91 0.38 0.23 1.59 Cu 1.39 1.42 0.60 0.36 2.44 Zn 5.17 3.57 4.85 1.54 21.0 Particulate form (µgkg-1) Cd 0.60 0.66 0.21 0.23 0.97 Pb 0.80 0.74 0.41 0.15 1.85 Cu 1.71 1.68 0.91 0.53 5.29 Zn 3.26 2.90 2.19 0.84 12.5 595 Poh Seng Chee et al: METAL GEOCHEMISTRY OF NERUS RIVER,TERENGGANU.