锡林郭勒草原湖泊沉积物中有机氯农药的分布、对映体特征及其对颤蚓的毒性效应

Organoehlorine Pestieides(OCPs) are priority pollutants and typical persistent organic pollutants(POPs). Because of their persistence, half-volatility and high toxicity in the environment, and biological accumulation through the food web, OCPs have great harm to the environment and human health. Because they were used largely and are difficult to degraded, OCPs are still the most widespread POPs in the environment despite their ban or restricted use in developed countries in1970 and in China in1983. .OCPs are transported into water throughdifferent pathways, such as industrial and domestic waste water, agricultural runoff, atmospheric deposition and soil erosion. Because of their hydrophobia, OCPs have a strong affinity for suspended particles and subsequently settle down into sediments under gravity. Therefore, sediments are thought to be one of the major sinks. However, OCPs in sediments can release into water by diffusion and resuspension and lead to there contamination of water.The study on transferring and transforming pathways of OCPs in water and sediments is very important and is a hotspot..In this project, water and sediments were collected from two main lakes in Xilin Gol to investigate the contamination status, distribution and sources of typical organochlorine pesticides in different seasons. Furthermore, enantiomeric fractions (EFs) of chiral organochlorine pesticides were also determined.The dynamic mechanism of transport and transform of OCPs between water and sediment as well as the influence of re-release of OCPs from sediment to lake water quality were discussed, and the enantioselective re-release of chiral OCPs was studied. A aquatic benthic organism (Tubifex tubifex) were used as the detector to access the accumulation and bioconcentration dynamic condition in organism tissue and the bioavailability of OCPs in sediment through sediment biological accumulation experiments combining field sampling with simulating lab test, meanwhile, the enantioselective bioaccumulation of chiral OCPs to tubifex was researched. Based on the tubifex acute toxicity tests in library and simulated lake pollution concentrations, determine the chronic toxicity of tubifex with sublethal concentrations and access the effects of OCPs against the contents of glutathione malondialdehyde(MDA)and Metallothionein(MT) and some enzyme activities (SOD,CAT,POD and GST) in tubifex. Finally comprehensively evaluate the pollution of the lake sediments. This project aims to make more accurate ecotoxicological forecasting and early warning of effects of pollution to the environment, providing the theoretical basis for pollution prevention and management of the lakes.

本项目以锡林郭勒草原两大湖泊为研究区域,以典型有机氯农药（OCPs）为研究对象, 拟于不同季节研究其在水体和沉积物中的污染现状,分布规律、来源及对映体特征，探讨OCPs在水体和沉积物间迁移转化的动力学机制，以及沉积物中OCPs的重新释放对湖泊水质的影响；以底栖动物-颤蚓为指示生物，将野外采样与室内模拟实验相结合，进行沉积物生物累积实验，得到OCPs在颤蚓体内的累积情况及富集动力学状况，探讨沉积物中OCPs的生物有效性,进一步在对映体水平上研究手性OCPs的选择性生物富集情况；同时，在进行颤蚓急性毒性试验的基础上，模拟沉积物中的污染浓度以及亚致死浓度进行慢性毒性试验，进一步研究OCPs对颤蚓某些生理指标（包括MDA、MT含量及部分酶活性）的影响，对湖泊沉积物污染进行综合评价。通过本项目的研究，以期为污染物对环境的影响做出更为准确的生态毒理学预测和早期预警，进一步为湖泊的污染防治提供理论依据。

选择19种有机氯农药及多氯联苯，六六六（α-HCH、β-HCH、γ-HCH、δ-HCH）、滴滴涕(六种)、氯丹（两种）、PCBs（PCB28、PCB52、PCB101、PCB118、PCB138、PCB153、PCB180）为研究对象，以锡林郭勒草原两大湖泊动态水和表层土为研究载体。分别研究水和表层土中有机氯农药和多氯联苯的残留含量以及表层土与上覆水之间的界面物质交换规律。. 选择三唑酮、水胺硫磷、甲霜灵、氟环唑和六六六（α-HCH、β-HCH、γ-HCH）为研究对象，利用高效液相色谱建立了甲霜灵、水胺硫磷对映体的分离方法，利用高效液相色谱-串联质谱建立了氟环唑对映体的分离方法，利用气相色谱对三唑酮及其代谢产物三唑醇的六个立体异构体进行了同时拆分，利用BGB-172色谱柱分析HCHs对映体。在颤蚓富集和代谢实验中，经溶剂萃取、SPE净化，建立了农药对映体在颤蚓、土壤和水样本中的残留分析检测方法。利用水体染毒和底层基质染毒两种培养方式对选定手性农药的富集、代谢行为进行了研究。结果显示，在两种方式培养颤蚓的富集实验过程中所选农药均能在颤蚓样本中检出，表明颤蚓在不同的生活环境下对所选农药均有一定程度的富集。在选定农药在培养基质中的分布和代谢行为研究中发现，所有农药在底层基质中均表现出明显的代谢。在添加颤蚓的底层基质中农药的代谢速率显著高于对照组，说明除去土壤微生物的代谢作用外，颤蚓表现出对底层基质污染的净化作用。而对上层水中农药的检测发现，颤蚓的存在有利于底层基质中的农药向上层水扩散，使底层固体基质中的污染物得以释放，可能对水系统中上层水生生物造成胁迫。利用颤蚓匀浆液制备了颤蚓的粗酶液，并建立了粗酶液蛋白含量、MDA含量、CAT、GST 及GR酶活性测定方法。. 选择HCHs、DDTs进行沉积物-颤蚓-锦鲤食物链实验，结果显示HCHs和DDTs在颤蚓体内有一定的富集，且富集浓度较大，富集倍数较高。锦鲤经食物链富集HCHs、DDTs均呈逐渐增加的趋势，生物放大系数大于1，表明存在生物放大效应。α-HCH在颤蚓体内富集没有出现对映体选择性富集现象，然而在锦鲤中出现显著的选择性富集现象。