Deep Sea Science Division, Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, Hainan 572000, China.
Deep Sea Science Division, Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences (CAS), Sanya, Hainan 572000, China.
Sci Total Environ. 2021 Apr 15;765:144228. doi: 10.1016/j.scitotenv.2020.144228. Epub 2020 Dec 24.
Large plastic litter (as opposed to microplastics and plastic pellets) could adsorb organic pollutants and thus pose a serious threat to the marine environment. We report high levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) adsorbed to plastic litter sampled from depths of 1800-3100 m in the Xisha Trough region of the northern South China Sea (NSCS). ∑PCBs on plastics ranged from 126.9-142.1 ng/g, with tri-PCBs accounting for 92-97% of the total PCB concentrations in all samples. Levels of ∑OCPs varied from 4280 to 5351 ng/g (average 4690 ng/g), with a total of 19 compounds detected in the seven samples. While no parent DDT (dichlorodiphenyltrichloroethane) was detected, op'-DDE (metabolite of DDT) was most abundant, with concentrations ranging from 947.5-1551.7 ng/g. ∑CHLs (heptachlor + heptachlor epoxide A + heptachlor epoxide B + cis-chlordane + trans-chlordane) ranged from 1083.1-1263.7 ng/g (mean 1153 ng/g) and accounted for 24% of ∑OCPs. Various compositional ratios of HCH (hexachlorocyclohexane) and DDT metabolites improved our understanding of the sources and transport pathways of OCPs. The total absence of DDT may be a "ghost indicator" of no recent DDT inputs into the oceans. There could well be inputs of DDT, but only as the degraded metabolites DDE and DDD when they are adsorbed to seafloor plastic litter. A comparison of HCH isomer ratios in seafloor plastics with technical HCH ratios revealed that HCHs were possibly not from early residues but from later inputs. An ecological risk assessment of the contaminants indicated a high risk from ∑DDTs, p,p-DDE, and γ-HCH in all the sampled locations. Finally, we propose a descriptive model depicting the movements and transportation of PCBs and OCPs from the ocean surface to seafloor plastics in the NSCS.
大塑料垃圾（与微塑料和塑料颗粒相对）可能吸附有机污染物，因此对海洋环境构成严重威胁。我们报告了从南海北部西沙海槽（NSCS）水深 1800-3100 米处采集的塑料垃圾中吸附的多氯联苯（PCBs）和有机氯农药（OCPs）的高浓度。∑PCBs 在塑料上的范围为 126.9-142.1ng/g，所有样品中总 PCB 浓度的 92-97%由三 PCB 组成。∑OCPs 的水平从 4280 到 5351ng/g（平均 4690ng/g）不等，在 7 个样品中检测到 19 种化合物。虽然没有检测到母体滴滴涕（二氯二苯三氯乙烷），但 o'-DDE（滴滴涕的代谢物）最为丰富，浓度范围为 947.5-1551.7ng/g。∑CHLs（七氯+七氯环氧化物 A+七氯环氧化物 B+顺式氯丹+反式氯丹）的范围为 1083.1-1263.7ng/g（平均 1153ng/g），占∑OCPs 的 24%。HCH（六氯环己烷）和滴滴涕代谢物的各种组成比提高了我们对 OCPs 来源和运输途径的理解。滴滴涕的完全缺失可能是海洋中近期滴滴涕输入的“幽灵指标”。可能有滴滴涕的输入，但只有当它们吸附在海底塑料垃圾上时，作为降解代谢物 DDE 和 DDD 输入。海底塑料中 HCH 异构体比率与技术 HCH 比率的比较表明，HCH 可能不是来自早期残留物，而是来自后来的输入。对污染物的生态风险评估表明，在所采样的所有地点，∑DDTs、p,p-DDE 和γ-HCH 均存在高风险。最后，我们提出了一个描述性模型，描述了 PCB 和 OCP 从海洋表面到 NSCS 海底塑料的运动和运输。
