摘要：
本文选取泥炭、生物质炭、木炭和活性炭4种含碳材料,结合以经济底栖生物菲律宾蛤仔(Venerupis philippinarum)为受试生物的生物累积实验和Tenax连续萃取法,阐述不同碳质对沉积物中4种菊酯类农药生物有效性的影响,并将Tenax萃取结果与底栖生物的累积结果进行了相关分析.结果表明,碳质的添加导致沉积物中菊酯类农药的快速脱附组分(Frap)降低,极慢速脱附组分(Fvs)增大,生物有效性降低,且4种碳质对Frap的影响有所不同,然而因为菊酯类农药的理化性质,Frap的差异并不显著.Tenax6 h和24 h的单点萃取组分与快速脱附组分相关性显著(P＜0.0001),基本可以代替完整的脱附动力学评价生物有效性,但是对于组成复杂,有机碳(OC)和黑炭(BC)含量高的沉积物进行研究评价时仍应注意由此产生的偏离.Tenax快速脱附组分与2种底栖生物累积结果之间具有显著的相关性(R2=0.38,P＜0.0001),表明在OC和BC含量不同的沉积物中,Tenax萃取技术也可以预测菊酯类农药在经济底栖生物菲律宾蛤仔体内的累积量,进而为沉积物中HOCs的环境质量和相关水产品的质量评估提供更为快捷、有效的参考依据.%Pyrethroids are a group of widely used synthetic insecticides with high hydrophobicity and aquatic toxicity.Previous studies have indicated that organic carbon (OC) especially black carbon (BC) plays an important role in the bioavailability of hydrophobic organic contaminants (HOCs) in sediments.However,the effect of OC on the bioavailability of pyrethroids in sediments is less konwn.In this study,the effect of four different types of carbon sorbents (peat soils,biochar,charcoal and activated carbon) on the bioavailability of sediment-associated pyrethroids was studied based on the bioaccumulation in Venerupis philippinarum and the Tenax desorption kinetics.The results showed that the carbon sorbents could decrease the fraction of rapid desorption (Frap) and increase the fraction of very slow desorption (Fvs) of pyrethroids in sediment.The sequestration capacity of four sobents were similar except for peat soils as the sorption capacity to HOCs of BC sorbents (biochar,charcoal and activated carbon) was found much stronger than that of humic substances (peat soils).Although the three BC sorbents have different specific surface area (SSA) and pore volumes,they still had a similar sequestration capacity to the bioavailability of pyrethroids,mainly due to the large molecular sizes and the nonplanar structure of pyrethroids.In addition,the efficiency of the carbon sorbent treatment was found to increase had the activated carbon in sediments increased.After 672 h Tenax extraction,about 77.5％-91.6％,71.9％-87.4％,68.7％-82.6％,65.6％-78.0％,and 47.8％-70.5％ pyrethroids was desorbed for the 0,0.7％,2％,3％,and 5％ activated carbon amended sediments,respectively.Significant correlations were observed between the Frap of pyrethroids with Tenax 6 h and with 24 h (P ＜0.0001) in sediment (F6/Frap =0.95,F24/Frap =1.18).Abnormal points were found when the sediments were amended with 5％ activated carbon.It demonstrated that the single time-point Tenax 6 h or 24 h,instead of the whole desorption kinetics can be used to evaluate the bioavailability of sediment-associated pyrethroids.However a large amendment of BC might make the method instability.Further,the relationship between the OC-normalized concentration of rapid desorption (Cs,rap) and the lipid-normalized concentration of pyrethroids in Venerupis philippinarum (Cb,lip) Was analyzed.There was a siginificant correlation between Cs,rap and Cb,lip (log Cs,rap =1.5 log Cb,1ip-0.49,R2 =0.38,P＜0.0001),indicating that Tenax extraction not only can predict the concentrations of prethroids in benthic organisms in complex matrix,but also can provide the basis for evaluating the bioavailability of sediment-associated HOCs in aquaculture pond and the quality of aquatic products.
