Distribution and Biological Assessment of Organochlorines (OCs) and Organophosphorous pesticides (OPs) in the Mid-western Coast of Korea

Abstract

Distribution and Biological Assessment of Organochlorines (OCs) and Organophosphorous Pesticides (OPs) in the Mid-western Coast of Korea

Choi jin young Directed by Prof. Shin Kyung Hoon Department of Environmental Marine Science Graduated School, Hanyang University of Korea

The distribution of organochlorines (polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs)) in sediment, seawater, fish, and clams collected from the mid-western of Korea was examined. Distribution of organophosphorous pesticides (OPs) in surface seawater and ATC-cleaving cholinesterase (ChE) activity were also examined. This study had three objectives: 1) to ascertain the distribution of PCB congeners, DDT metabolites, and HCH isomers in surface sediments and marine organisms (clams, oysters, and fish) along the mid-western coast of Korea and understand the accumulation patterns of these chemicals in those organisms 2) to study the temporal and spatial distribution of OPs in Asan Bay, Korea , with the aim of understanding the distribution of OPs in estuarine environments compared to OCPs 3) to evaluate the possibility of using ChE analysis in Manila clams (Ruditapes philippinarum) as a useful biomarker for OPs exposure in coastal regions influenced by nearby agricultural areas

The distribution and bioaccumulation of PCBs, DDTs, and HCHs was investigated in sediment and Manila clams (R. philippinarum) collected from the mid-western coast of Korea. Concentrations of ?PCB, ?DDT and ?HCH were determined to be in the range of 0.57 - 1.72, 0.13 - 0.34, and 0.09 - 0.30 ng/g dw (dry weight), respectively, in the sediment samples. In this study, the levels of these compounds were relatively lower than the same for other contaminated areas. The spatial distribution of these chemicals seemed closely related to anthropogenic activities. The concentrations of ?PCB, ?DDT, and ?HCH measured in clams tissues were 87.4 ? 43.4, 31.2 ? 12.7, and 14.5 ? 5.4 ng/g lipid. ?PCB and ?DDT concentration in sediment showed significant relationship with ?PCB and ?DDT concentrations in clams. Significant correlation was observed between log BSAF in clams and log Kow for PCB congeners and DDT metabolites. These findings support the notion that levels of PCBs and DDTs, very hydrophobic chemicals, in clam tissue reflect sediment pollution by PCBs and DDTs that occurs through biomagnification and bioaccumulation. The PCBs and OCPs that had accumulated in the Manila clams and oysters (Crassostrea gigas) collected at 3 sites were compared. Highly chlorinated PCBs were more commonly found in oyster tissues than in clam tissues. ?PCB and ?DDT concentration in the intertidal sediments of Asan Bay ranged from 1.90 - 3.27 ng/g dw (dry weight) and 0.51 - 1.26 ng/g dw, respectively. ?PCB concentration in the tissues of greenlings (Hexagrammos otakii), olive flounders (Paralichthys olivaceus), and finespotted flounders (Pleuronichthys cornutus) was 1.27 ? 0.55, 1.30 ? 0.71, and 1.19 ? 0.43 ng/g ww (wet weight), respectively. The profiles of PCBs in the sediments and 3 species of fish differed, as witnessed by the dominance of tetra- to penta-chlorinated congeners in sediments, while penta- to hexa-chlorinated congeners dominated in fish. ?DDT concentration was 0.67 ? 0.52, 0.79 ? 0.61, and 1.58 ? 1.05 ng/g ww, respectively, in the tissues of greenlings, olive flounders and finespotted flounders. P.p?-DDE appeared to be the most important metabolite of DDT in the fishes studied. The concentrations of PCBs and OCPs measured in this study for fish were generally lower than those of previous studies. The distribution characteristics of organophosphorous pesticides (OPs) were studied from May to September, 2006 in Asan Bay, Korea. During the study period, 28 kinds of OPs that had dissolved in surface water and adsorbed on suspended particle were measured. In the surface water, the dominant OPs were IBP and DDVP, whose concentrations ranged from not detected (ND) to 2014 ng/L for IBP and 3 to 696 ng/L for DDVP, respectively. In 2006, the highest concentrations of OPs were recorded in the surface waters of Asan Bay. The distribution of OPs in Asan Bay was also studied from February to September, 2008. IBP, ranging from ND to 377 ng/L, was the most abundant of the 29 kinds of OPs detected during the study period in the sea water of the Asan Bay. The concentrations of diazinon, azinphos ethyl, malathion, demeton-O, and DDVP, commonly observed in the study area, were in the range of ND ? 307, ND ? 1997, ND ? 3013, ND ? 2403, and ND ? 283 ng/L, respectively. Between August 2006 and 2008, the concentrations of OPs generally decreased with increasing salinity of water, implying progressive dilution of pesticides in the estuarine system. The OPs in Asan Bay came not only from Asan Lake and Sabkyo Lake but also from tributaries around the Bay. DDVP, IBP, diazinon, phorate, azinphos ethyl and chlorfenvinfos had higher adsorption capacity onto suspended particle than the other OPs in Asan Bay in 2006. Ten OPs, including diazinon, were detected in suspended particles in Asan Bay in 2008. In the study area, the adsorption coefficients (Kd) of OPs were closely related to the log Kow of each compound. The OPs residue in Asan Bay was relatively higher than the same in other areas of Korea. Concentrations of the observed OPs did not exceed the seawater quality standard of Korea. Because of differences between the usage and regulation of those chemicals, OPs distribution was different significantly from OCPs distribution in estuarine environments. The acetylthiocholine (ATC) ? cleaving cholinesterase (ChE) activity in Manila clam, which is widely distributed throughout the coastal environment of Korea, was assayed as a potentially useful biomarker of organophosphorous pesticides (OPs). A clear dose?response relationship was determined between inhibited ChE in the adductor muscles of clams and four OPs (methidathion, chlorpyrifos, diazinon, IBP) which are heavily used OPs in Korea. The measured EC50?24h values of methidathion, chlorpyrifos, diazinon, and IBP for Manila clams were 7.16 ?g/L, 0.34 mg/L, 3.01 mg/L, and 3.41 mg/L, respectively. In field studies, ChE activity in Manila clams collected from 23 stations in the mid-western coastal region demonstrated spatial variation with statistical differences. These results suggest that ChE activity in R. philippinarum is a potential biomarker for assessing organophosphorous pesticide contamination in coastal environments. These findings enhance understanding of the distribution of organic contatminants, such as PCBs, OCPs and OPs, in coastal environments on the mid-western coast of Korea and suggested the biological implications of those pollutants.