Sediment Record Of PAHs, OCPs And PBDEs In Meiliang Bay And Xukou Bay In Taihu Lake, East China

In recent years, much more attention has been paid to the Asian plateau lakes and plain lakes concern on organic pollutants . The "global distillation/fractionation" hypothesis of the organic pollutants considers that the temperature discrepancies in different latitudes lead to the contamination in the high latitude region caused by the organic pollutants in tropic possibly through the distillation/fractionation effect. The Yangtze River locates in the subtropical zone, whether that the extremely fast economic development in the recent 20 years has caused serious organic pollutants in the water system and lakes in the area has aroused people more and more concerns. The existing research on the organic pollutants in that area is very limited in respect of the width and depth, especially the research on tai-lake sediments. So, the organic pollutants analysis, history tracing and environment risks evaluation focusing on the tai-lake sediments are very important for people to comprehend the time-space distribution, the pollutant source, the composition character and the lake contaminations caused by human activities of the organic pollutants in that area; what's more, it also supply a reference example to study in the similar lakes in other areas.This paper based on a full consultation on the history of human activities, geographic and geomorphic features and social economic development in the Taihu lake river basin, uses the high resolution sediment records, analyses and measures the vertical distribution and contamination characters of the toxic, bio-accumulative, semi-volatile POPs in the sedimentary cores in typical bays of the up and down Taihu regions (Meiliang Bay and Xukou Bay), and set up the corresponding time index by Pb dating, to rebuild the aggrading history of the PAHs, OCPs and PBDE in tai-lake, and to do a extended discussion about the relationship between the tai-lake POPs and the land development and utilization during the economic development, the locomotive fuel consumption , the contaminations emission; what's more, the paper also evaluates the environment risks of partial POPs in the tai-lake sediments referring to the accepted method by US. EPA.According to the analysis of the PAHs in the sediments, the origin contains natural diagenesis, oil inputs and fuels emission; of which petroleum direct input and oil combustion source are increasing. According to the analysis of the OCPs in the sediments, following the big scale land development in the regional level, the OCPs contamination transfers partly from the soil to the sediments in the water system; otherwise, the new input DDTs are transferred to the tai-lake circumjacent area, which may relates to the usage of Dicofol. According to the analysis of the PBDE, the sediments content presented a trend of greatly increasing in 90s in the last century. The homologues distribution displays that this relates to the usage of PBDE in the circumjacent environment. The research also reveals that there has been a decrease of the PAHs and PBDE since the 1991 cataclysmal diluting in the water system.Contrasting to the national and foreign lakes and water systems that have been studied, the content of PAHs, OCPs and PBDE in tai-lake sediments is in a low or medium level as a whole, and the environment risks evaluation of PAHs and OCPs is in the safe range, but there also exists some compounds over the ERL, which hints that some environment risks factors exist.