洞庭湖沉积物中持久性有机有毒物质的分布、评价与源解析

摘要

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/y-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-C6H6C16 and ∑HCHs should be seriously considered as well.%为揭示洞庭湖沉积物中六氯环己烷(HCHs)、双对氯苯基三氯乙烷(DDTs)、多环芳烃(PAHs)的分布特征及其来源,评价存在的生态风险,于2015年12月采集洞庭湖沅江市南嘴等31个点位0～20cm沉积物,测定了沉积物样品中HCHs、DDTs、PAHs的含量.结果发现,南洞庭湖点位∑HCHs和∑PAHs含量变化最大,西洞庭湖点位∑DDTs和∑OCPs含量变化最大;沉积物中HCHs的空间分布为东洞庭含量最高,其次为东洞庭湖与南洞庭湖的交界处,其它区域HCHs含量较低,DDTs含量除了在西洞庭湖北部含量较低外,其它区域DDTs含量都相对较高,并出现了多个高值区域,PAHs含量空间分布的最大值出现在东洞庭湖与南洞庭湖交界处,其次为西洞庭湖北部和中部区域;污染源分析发现,洞庭湖沉积物中的23种有机化合物聚类归为3类,而31个监测点归为4类所有样品中α-HCH/γ-HCH的比值为0.66左右,可以认为洞庭湖沉积物中的HCHs来源于农业生产,并有林丹的使用.而p,p'-DDE/p,p'-DDT的比值发现,沉积物中有新的DDTs输入,比值法得出沉积物中的PAHs主要来自于燃烧源和石油源的污染.风险评价发现,苊烯(Acy)在洞庭湖中存在轻微污染,其它环芳烃在沉积物中不存在污染,而沉移物中o,p'-DDT、p,p'-DDT和∑DDTs残留量存在一定的生态风险,此外苯并[b]荧蒽(BbF)、苯并[k]荧蒽(BkF)、苯并[ghi]花(B ghi P)、茚并[1,2,3-cd]芘(Incd P)、α-C6H6C16、β-C6H6Cl6、δ-C6H6C16及∑HCHs残留量均有一定检出,应引起重视.