Distribution, assessment and sources analysis of persistent organic toxic chemicals in sediments of Dongting Lake
YANG Hai-jun1, ZHANG Hai-tao1, LIU Ya-bin1, XU Yun-hai1, HUANG Zhong-ting2
1. College of Plant Protection, Hunan Agricultural University, Changsha 410128, China;
2. Environmental Monitoring Station of Hunan Province, Changsha 410014, China
In order to reveal the distribution characteristics and the sources of HCHs, DDTs and PAHs in sediments of Dongting lake, and assess their ecological risk, this study investigated the contents of HCHs, DDTs and PAHs in sediments (0~20cm) from 31sample sites of Dongting Lake (Nanzui Town, Yuanjiang city) in Dec, 2015. The results showed that the ∑HCHs and ∑PAHs content variation in South Dongting Lake was the highest, and the highest content variation of ∑DDTs and ∑OCPs was in West Dongting Lake. Based on the spatial distribution, the content of HCHs in East Dongting Lake was the highest, the next was on the border between East Dongting Lake and South Dongting Lake, and the other areas were low. The contents of DDTs in other areas were relatively high except the north part of West Dongting Lake, and some high value areas were found. The maximum content value of PAHs was found on the border between East Dongting Lake and South Dongting Lake, the second was the north and the central part of West Dongting Lake. Pollution sources analysis found that those 23kinds of compounds clustering in sediments of Dongting Lake could be classified into three categories, and 31monitoring points could be classified into four categories. Since the α-HCH/γ-HCH in all samples was 0.66, with the finding of lindane, it could be inferred that HCHs in the sediments of Dongting Lake mainly came from agricultural production. While, according to the p,p'-DDE/p,p'-DDT, new DDTs input had been found in the sediments. The study also suggested that the major sources of PAHs in sediments were coal and petroleum combustion and petroleum leakage. At last, by the risk assessment, Acy had caused slight pollution in the Dongting Lake, while other PAH had no effect. However, the residues of o,p'-DDT, p,p'-DDT and ∑DDTs would pose ecological risk. Furthermore, the detection of the residues of BbF, BkF, B ghi P, Incd P, α-C6H6Cl6, β-C6H6Cl6, δ-C6H6Cl6 and ∑HCHs should be seriously considered as well.
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