State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China; School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China.
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China; School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China.
Environ Pollut. 2018 Feb;233:340-347. doi: 10.1016/j.envpol.2017.10.078. Epub 2017 Nov 5.
The sedimentary core in remote alpine lakes has been recognized as an ideal proxy to reconstruct the emission and air deposition histories of persistent organic pollutants (POPs). Nevertheless, POPs formerly stored in a catchment might also contribute to the variation in the lake sediment by lateral remobilization. In this study, to reveal the relative importance of lateral remobilization, we measured the vertical profiles and isomeric ratios of dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs) and endosulfan in a dated sedimentary core collected from Lake Yamzho Yumco in the southern Tibetan Plateau. In addition to the flux peaks in the 1970s corresponding to the heavy atmospheric deposition of DDTs and HCHs, these pollutants' fluxes displayed rebounds in the flood periods, with characteristic low ratios of DDT/DDE (α-/β-HCH). This might indicate a massive remobilization of "weathered" pesticides from catchment soil to the lake because of strong hydro-dynamics. Moreover, the relative contribution of lateral remobilization to the lake sediment in the past decades was recognized through the correlation between DDT/DDE (α-/β-HCH) ratios and ∑DDT (∑HCH) fluxes. The results showed that the lateral remobilization contributed to 20-42% of the total fluxes. This study discriminated the air deposition from the contribution of lateral remobilization, which improves current understanding of the vertical POPs profiles in the sedimentary core.
偏远高山湖泊中的沉积岩芯已被公认为重建持久性有机污染物（POPs）排放和大气沉降历史的理想替代物。然而，以前储存在集水区的 POPs 也可能通过侧向再迁移而导致湖泊沉积物的变化。在这项研究中，为了揭示侧向再迁移的相对重要性，我们测量了取自青藏高原南部的 Yamzho Yumco 湖的一个定年沉积岩芯中滴滴涕（DDTs）、六氯环己烷（HCHs）和硫丹的垂直分布和同系物比值。除了与 DDTs 和 HCHs 大量大气沉降相对应的 20 世纪 70 年代的通量峰值外，这些污染物的通量在洪水期出现反弹，表现出 DDT/DDE（α-/β-HCH）比值特征较低。这可能表明由于强水动力作用，大量“风化”农药从集水区土壤向湖泊再迁移。此外，通过 DDT/DDE（α-/β-HCH）比值与∑DDT（∑HCH）通量之间的相关性，我们认识到过去几十年侧向再迁移对湖泊沉积物的相对贡献。结果表明，侧向再迁移对总通量的贡献为 20-42%。这项研究区分了大气沉降与侧向再迁移的贡献，从而提高了对沉积岩芯中垂直 POPs 分布的认识。
