胞外聚合物和腐殖质对毒死蜱于摇蚊属生物利用率的影响

Effects of Extracellular Polymeric and Humic Substanceson Chlorpyrifos Bioavailability to Chironomus Riparius

以4类有机物考察毒死蜱对摇蚊幼虫生物利用率的影响:(1)购买的胞外聚合物(EPS),(2)由沉积微生物制取的EPS,(3)购买的腐殖质,(4)从北方湖泊里提取的腐殖质。每种有机物以3种浓度,采用14C同位素示踪法确定摇蚊幼虫对毒死蜱的摄取量。幼虫对毒死蜱的常规摄取量随EPS和腐殖质的增加而减少。而EPS对幼虫摄取毒死蜱的量又比腐殖质少得多:其中,幼虫于毒死蜱对购买的EPS摄取量减少了94%,对制备的EPS摄取量减少了88%,对购买的腐殖质摄取量减少了59%,对制备的腐殖质摄取量减少了57%。研究发现:沉积物浓度,制备方法,分子质量对应的生态毒理学,对摇蚊幼虫于毒死蜱摄取量的差异较小;死亡摇蚊幼虫的被动摄取量(吸附溶解)占活的摇蚊幼虫食用摄取量的40%,这对研究了解摇蚊幼虫对毒死蜱的摄取机制是重要的。结果表明,EPS和腐殖质对毒死蜱生物利用的影响是负面的,因此可用来调节水生环境中有机污染物的生物利用率。

The role of sediment organic matter quality andquantity for chlorpyrifos bioavailability was studied inexperiments with Chironomus riparius larvae and with four types of organic matter; （1）commercially available extracellular polymeric substances （EPS）, （2） EPS produced bysediment microbes, （3） commercially available humic substances and, （4） humic substances extracted from a boreal lake. The effects of each type of organic matter were assessed at three concentrations. We used a 14C-tracer approach to quantify uptake of chlorpyrifos in the larvae, and the partitioning of the insecticide within the microcosm. We also found differences in chlorpyrifos uptake, and sediment concentrations between treatments with commercially available and complex polymers, suggesting that minor differences in the quality of relatively simple organic molecules can affect contaminant behaviour in ecotoxicological studies. Passive uptake in dead controls was 40% of that in living larvae. Therefore, both passive and digestive uptake were important processes for chlorpyrifos uptake bylarvae. Our results show that both EPS and humic substances affect chlorpyrifos bioavailability to sediment biota negatively and contribute to the understanding of the processes that regulate organic contaminant bioavailability in aquatic environments.