近百年来大辽河口潮间带中滴滴涕(DDTs)的沉积记录及其对人类活动的响应
摘要
<p>Dichlorodiphenyltrichloroethanes (DDTs) are still detected in various environmental matrices,although their usage in agriculture has been banned for about 30 years in China.Intertidal zone,as the intersection area of land and sea,is the final sink for contaminants.To comprehensively understand the deposition features of DDTs in intertidal sediment of Daliao River Estuary,a sediment core was sampled in this study.Combined with the dating data,the distribution,potential risk,source and fate of DDTs were investigated.The results showed that DDTs concentrations ranged from 0.313 ng&middot;g~(-1) to 4.116 ng&middot;g~(-1) (median:2.061 ng&middot;g~(-1)),with p,p&#39;-DDTs being the major components.Interestingly,the peak of DDTs concentrations (3.4364.116 ng&middot;g~(-1)) during 1988 1996 corresponded well with the peak of pesticide production during 19711981,and a 15-year-round time lag was observed between these two peaks.Possible usage of technical DDT was implied after year 2000 for the control and prevention of disease in Liaoning Province.The risk assessment of DDTs revealed that concentrations of DDT and DDE in sediment core rarely (&lt;25%) showed negative effect,while concentrations of DDD and total DDTs in the depth of 044 cm occasionally (25%50%) showed negative effect.The specific ratios of DDTs demonstrated that DDTs in the intertidal sediments were mainly from historical use of technical DDT rather than the use of dicofol.DDE and DDD were the main degradation products of DDT in the deeper layer (62110 cm) and shallower layer (061 cm),respectively.Further analysis revealed that the increased TOC content caused by human activities after year 1971 was the main reason that led the sediment environment changing from aerobic environment to anaerobic environment.What&#39;s more,DDTs concentrations in sediment core had strong positive correlations with sediment properties (TN,TP and TOC) (P &lt;0.01),and also had a signific