摘要:
本研究以经济底栖生物菲律宾蛤仔和河蚬为受试生物,分别对不同浓度梯度的海洋和淡水底泥中9种代表性有机氯农药(OCPs)进行累积实验;同时采用Tenax连续萃取法研究2类底泥中OCPs的脱附动力学,提供简单、快速评价养殖底泥中OCPs生物有效性的方法,并将Tenax萃取结果与2种底栖生物的累积结果进行比较。结果表明,菲律宾蛤仔和河蚬对OCPs的生物-底泥富集因子(BSAF)分别为0.31~1.89和0.12~2.12,且底泥中有机碳标化的OCPs浓度与生物体内脂肪标化的OCPs浓度之间的相关性较差。Tenax脱附动力学的结果表明,2类底泥中OCPs的快速脱附比例(Frap)均在50%左右,其快速、慢速和极慢速脱附速率常数数量级分别为10-1、10-2和10-4。Tenax快速脱附组分与2种底栖生物累积结果之间具有良好的相关性(r2=0.75,P<0.0001),表明Tenax萃取技术可以预测OCPs在底栖生物体内的累积量,并且该方法克服了大型底栖生物累积实验结果重复性较差等缺点。另外通过与基于热力学平衡的方法对比发现,Tenax萃取技术更适用于滤食性或可消化底泥的底栖生物对底泥污染物的富集;同时Tenax 6 h和24 h单点萃取技术可以作为简单快速评价底泥疏水性有机污染物(HOCs)生物有效性的替代方法,进一步为养殖领域的底泥污染状况以及相关水产品的质量安全和食用风险提供生物有效性评价依据。
Abstract:
In the present study, we used two economic benthic organisms Ruditapes philippinarum and Corbicula fluminea to study the bioaccumulation of nine organochlorine pesticides (OCPs) from marine or freshwater sediment with different concentration gradients. In parallel, we applied Tenax-based sequential extraction to assess the desorption kinetics of these OCPs from the tested sediment samples in comparison with their bioaccumulation characteristics in the two model organisms. This approach provided a simple, rapid way to evaluate the bioavailability of these aquaculture sediment-associated chemicals. The results showed that the biota-sediment accumulation factor (BSAF) for Ruditapes philippinarum and Corbicula fluminea were within the range of 0.31-1.89 and 0.12-2.12, respectively. A poor correlation was observed between organic carbon normalized concentrations of OCPs in the sediment studied and the lipid-normalized concentrations of OCPs in organisms. The Tenax desorption kinetics study showed that the rapidly-desorbing fraction (Frap) of OCPs was approximately 50% for both marine and freshwater sediments, and the rate constants for the rapidly-, slowly- and very slowly-desorbing fractions were of the order of magnitude of 10-1, 10-2 and 10-4, respectively. The lipid-normalized concentrations of OCPs in the test organisms were significantly correlated with their concentrations of the rapidly-desorbing fraction in Tenax extraction (r2=0.75, P<0.0001), suggesting the predictive power of Tenax-based extraction for the bioaccumulation of OCPs in benthic organisms. This method overcomes the poor reproducibility of conventional bioaccumulation studies using benthic organisms. Compared with themodynamic equilibrium-based predictions, Tenax extraction is more suited to predict the bioaccumulation of sediment-associated chemicals in filter feeders that can ingest sediment particles. 6-h and 24-h Tenax extractions can therefore serve as a simple, rapid altemative to evaluate the bioavailability of hydrophobic organic contaminants in sediment, providing a sound basis for assessing aquatic product safety and human health risks associated with its consumption.
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