Distribution, Migration And Transformation Of Polychlorinated Biphenyls And Short Chain Chlorinated Paraffins In Typical Regions

Persistent Organic Pollutants (POPs) are chemicals that have been widely used in industry and agriculture, but their properties such as high stability, lipotropy and toxicology can also pose risk to the environment and ecological systems. In the past decades, environmental accidents, such as the Japanese rice bran oil event and the event of Taiwan oil spill, frequently occurred which strengthens the determination of related regulatory agencies. The Stockholm Convention which was approved in2001, officially opened a new chapter to reduce and control POPs among international communities. In this study, the occurrence, migration and transformation of representative POPs such as polychlorinated biphenyls (PCBs) and emerging POPs such as short chain chlorinated paraffins (SCCPs) were investigated in typical environments.Urban wastewaters from households and industrial production process collect in waste water treatment plants (WWTPs). Sewage sludge is usually considered to be an important source of POPs, because it contains large amounts of organic particulate matter. Firstly, the distribution of PCBs in a riparian zone affected by the Qinghe WWTP in Beijing and the potential transfer from WWTP effluent to the terrestrial compartment by aquatic insects was studied. A relatively narrow range of δ13C values was found among most invertebrates (except butterflies, grasshoppers), indicating a similar energy source. In collected samples, soil dwelling invertebrates showed higher concentrations than phytophagous insects at the riparian zone. Although biota-sediment/soil accumulation factors (BSAFs) for ΣPCBsCBs were relatively low, high bioaccumulation factors (BAFs,71000-870000) were observed in collected aquatic invertebrates. Emergent aquatic insects such as chironomids could carry waterborne polychlorinated biphenyls (PCBs) to the terrestrial compartment via their lifecycles. The estimated annual transfer amount of PCBs for chironomids ranged from0.66-265ng·m-2·y-1. A high prevalence of PCB-11and PCB-28was found in WWTP effluent, sediment, reeds, aquatic and phytophagous organisms. However, the mid-chlorinated congeners (PCB-138and PCB-153) became dominant in chironomids, dragonflies and other terrestrial organisms, indicating a selective biodriven accumulation and transfer of different PCB congeners.SCCPs are semivolatile organic compounds (SVOCs) and have been of considerable concern in recent years due to their high production volumes, environmental persistency and potential for long range atmospheric transport. However, there is currently a lack of information about their environmental distribution and fate, especially in foodstuffs and vegetation.Seafood samples were collected from Dalian, China to study the accumulation and distribution characteristics of short chain chlorinated paraffins (SCCPs) by GC/ECNI-LRMS.CCPs (dry weight) were in the range of77-8250ng·g-1, with the lowest value in Scapharca subcrenata and highest concentration in Neptunea cumingi. The concentrations of ΣSCCPs(dry weight) in fish, shrimp/crab and shellfish were in the range100-3510,394-5440, and77-8250ng·g-1, respectively. Overall, the C10and C11homologues were the most predominant carbon groups of SCCPs in seafood from this area, which accounted for61.1%of the total, and a relatively higher proportion of C12-13was observed in seafood with higher concentrations of ΣSCCPs. With regards to chlorine content, Cl7, Cl8and Cl6were the major groups. Significant correlations were found among concentrations of different SCCP homologues (except Cl5vs. Cl10), which indicated that they might share same sources and/or have similar accumulation, migration and transformation processes.The atmosphere is recognized as the main environmental medium for the global transport of POPs. Atmpospheric POPs can be partition to vegetation and other medium, which can have some effects on the global ecosystem. Vegetation can take up considerable amounts of SVOCs from the atmosphere and can also act as indicators of local contamination. In this work, paired pine needles and bark were sampled around Beijing during winter and summertime to investigate the distribution and seasonal variation of SCCPs in urban areas. Needles samples ranged3.03-40.8μg/g on a lipid normalized basis (lw) with a geometric mean (GM) of11.8μg/g lw and5.79-37.5(GM16.9) μg/g lw for bark. Average congener group profiles showed almost equal contribution of all four carbon groups (C10-13) in wintertime whereas higher abundances of C10(～40%) and C11(～30%) carbon groups were found during the summer. Furthermore, the air-needle partitioning behavior of SCCPs was also investigated, and it was suggested that uptake of SCCPs occurred mainly via kinetically limited gaseous deposition and particle bound deposition in the investigated area.