Organohalogenated Pollutants In Aquatic Organisms From The Pearl River Delta, South China: Spatial And Temporal Distribution, Bioaccumulation And Human Dietary Exposure Assessment

Organohalogen pollutants(OHPs) are organic pollutants with halogen atoms, and most of OHPs are well-known for their persistence, bioaccumulation, long-range transport potential and toxicity. Hence, the research on the environmental occurrence and behavior has become an important issue in the worldwide. The Pearl River Delta is one of the most development regions in China, and is also a potential pollution area with the high levels of various OHPs such as organochlorine pesticides(OCPs), polychlorinated biphenyls(PCBs), polybrominated diphenyl ethers(PBDEs) and other halogenated flame retardants(HFRs).A suite of legacy and emerging OHPs including dichlorodiphenyltri-chloroethane and its metabolites(DDTs), hexachlorocyclohexanes(HCHs), PCBs, PBDEs, short-chain chlorinated paraffins(SCCPs), decabromodiphenyl ethane(DBDPE), Dechlorane Plus(DP) were investigated in the present study. Three fish species, mud carp(Cirrhinus molitorella), tilapia(Tilapia nilotica), and plecostomus(Hypostomus plecostomus), from the major river networks in the Pearl River Delta(PRD) were analyzed to understand the contaminant status and explore the relationships between OHPs profiles and anthropogenic activities. Various marine organisms, including wild fish and invertebrates, were collected from the Pearl River Estuary(PRE), South China to investigate the current contamination status in marine organisms of this area after implementing the Stockholm Convention in China, to examine the species-specific bioaccumulation of OHPs, and to assess the potential health risks associated with seafood consumption by local residents of this region. In addition, the bioaccumulation characteristics of SCCPs were studied in the freshwater ecosystem from a typical highly contaminated site, a e-waste recycling area in South China.The concentrations of DDTs, HCHs, PCBs, SCCPs, PBDEs, DBDPE, and DP in the freshwater fish from the main river networks in PRD ranged from 380–57000, 5.5–100, 30–4200, 460–19000, 6.9–690, 0.29–460 and 0.09–20 ng/g lipid weight, respectively. Congener profiles or chemical compositions of PBDEs, DP, DDTs, and HCHs in plecostomus differed significantly from those in the other two fish species, which can be ascribed to species-specific metabolism. Industrial and urban activities resulted in elevated levels of PCBs and PBDEs in the metropolitan area. E-waste recycling activities have greatly impacted on the adjacent aquatic environment. The contaminant pattern of OHPs in the PRD region was governed by industrial sources and agrochemical sources.The concentrations of OHPs including DDTs, PCBs, PBDEs, SCCPs and several other HFRs in marine organisms from the PRE were at global median levels. DDTs, HCHs, PCBs, PBDEs, SCCPs and DBDPE all showed decreases, but no significant difference was found in the other HFR levels between the two sampling periods because of low detection rates and low concentrations. SCCPs and DDTs were predominant in all marine species from the PRE, collectively constituting >70% of OHPs. The concentration and contaminant pattern exhibited species-specific values in marine organism, and various factors such as habitat, feeding habit, trophic level occupied, and metabolic capability for xenobiotics can contribute to these species differences. The average EDIs of DDTs, PCBs, SCCPs, PBDEs and the alternative halogenated flame retardants(AHFRs) via seafood consumption were estimated to be 31(ng/kg)/d, 11(ng/kg)/d, 115(ng/kg)/d, 0.94(ng/kg)/d, and 0.18(ng/kg)/d, respectively.This suggested that consuming seafood in the Pearl River Estuary might not pose a significant health risk to local residents in China.SCCPs were detected in all aquatic organisms from the e-waste recycling site. It was observed that preferential distribution in liver compared to muscle for the SCCP homologue groups with the longer carbon chain and higher chlorine content. The Log BAF of fish species and BSAF of benthic invertebrates were 2.47–3.52 and 1.26–4.53, respectively. The relationship between BAF and Log Kow exhibited species-specifi profiles. The M/(M+L) and BSAF were both negative relationship with the Log Kow. The TMF value of SCCPs was 0.59, indicating SCCPs was not biomagnified in the present food web.