Historical Trends And Source Apportionment Of CPs In Sediment Cores From The Lakes Of The Lower-middle Reaches Of Yangtze River

The sediment cores from the lakes?Chaohu Lake,Daguan Lake and Longgan Lake?of the lower-middle reaches of Yangtze River were selected as the research object in this paper.The purposes of this study were to research concentration,composition and vertical distribution of chlorophenols?CPs?,identify the sources of CPs and ecological risk assessment of pentachlorophenol?PCP?in the sediments.First,a method for determination of CPs in sediments was developed using ultrasonic solvent extraction followed by solid-phase extraction?SPE?,derivatization and gas chromatography-mass spectrometry?GC-MS?analysis.Then,the concentration,composition and vertical distribution of CPs in the sediment cores were thoroughly discussed by the concentration data of CPs.Further then,the Positive Matrix Factorization?PMF?model was used to identify the possible CPs sources and analyze source contributions in the present study.Finally,we applied the species sensitivity distribution?SSD?model and equilibrium partitioning approach?EqPA?to estimate the ecological risk of PCP in the river sediment.The next are the main results:?1?A method for determination of CPs in sediments was developed using ultrasonic solvent extraction followed by solid-phase extraction,derivatization,and GC-MS analysis.The method showed good performance with the recovery efficiencies of target CPs in spiked sediment at 73.2-105.6%?RSD<11.9?,and some effective operational details and parameters were studied and optimized.The obtained results show that the present method is a sensitive,simple,low cost and highly feasiblemethod for determination of CPs in sediment samples.?2?The geometric means of total concentration of CPs in the sediment cores from the eastern half of Chaohu Lake?CH1?,the western half of Chaohu Lake?CH2?,Daguan Lake?DG?and Longgan Lake?LG?were 11.78,6.30,10.82 and 4.91 ng g^-1,respectively.Tetrachlorophenol?TeCP?and PCP were the dominant congeners in the cores from CH1,CH2 and DG,while monochlorophenol?MCP?and dichlorophenol?DCP?constituted a main fraction in the upper sediments from LG.?3?Three sources of CPs in sediments were identified by PMF model.Their relative contributions to total concentration of CPs in sediments were 29%,60%,31%and 23%for industrial pollution source;53%,18%,42%and 30%for agriculture pollution source;and 19%,23%,27%and 47%for biodegradation and humic acid chlorination in CH1,CH2,DG and LG,respectively.?4?SSD method was applied to predict no effect concentration of PCP in water(PNEC_wate).Then,no effect concentration of PCP in sediment(PNEC_sed)was estimated by EqPA.The results of prediction shown that the ecological risk of PCP in sediments were negligible in this paper.