不同污染方式进入土壤的氯氰菊酯在蚯蚓体内的蓄积特征及其生长毒性

Bioaccumulation of Cypermethrin in Earthworm and Its Effects on Earthworm Growth

农药污染严重威胁我国的土壤生态系统安全。选择我国应用较广的氯氰菊酯为代表性农药污染物,采用一次和叠加的污染方式模拟氯氰菊酯进入土壤并逐渐累积的过程,以云南耕地常见的蚯蚓优势种——皮质远盲蚓(Amynthas corticis)为实验生物,研究了氯氰菊酯在土壤中的降解变化,以及蚯蚓对不同污染方式进入土壤的氯氰菊酯吸收蓄积的累积特征和生长毒性响应。结果显示,不同污染方式进入土壤的氯氰菊酯,在土壤中的降解均符合一级动力学特征c=c 0 e-kt,以一次污染方式进入土壤的氯氰菊酯降解半衰期为27.7~28.9 d;以叠加污染方式进入土壤的氯氰菊酯降解半衰期为25.7~26.6 d。氯氰菊酯浓度为4~6 mg·kg^(-1),暴露55 d时,蚯蚓对以一次污染方式进入土壤的氯氰菊酯蓄积量为0.34~0.73 mg·kg^(-1),生物-土壤蓄积因子(F BSA)为0.85~1.05;蚯蚓对以叠加污染方式进入土壤的氯氰菊酯蓄积量为0.86~1.51 mg·kg^(-1),F BSA为1.16~1.42。与一次污染方式比较,以叠加污染方式进入土壤的氯氰菊酯,更有利于蚯蚓对其进行生物富集,从而表现出较强的生长毒性。研究结果可为土壤农药叠加污染累积的生态风险防治提供基础数据和理论依据。

The pollution of pesticides seriously threatens the soil ecosystem in China.An experiment was conducted using the one-time pollution method and the multiple-time superimposed method to investigate the degradation characteristics of cypermethrin in soil and the bioaccumulation of cypermethrin in Amynthas corticis along with its influence on the growth of this earthworm.Results showed that the degradation of cypermethrin in soil using one-time pollution method and the multiple-time superimposed method both accord with the first-degree dynamic model:c=c 0 e-kt.The half-life of cypermethrin in soil was 27.7~28.9 d for the one-time pollution methods and 25.7~26.6 d for the multiple-time superimposed methods.After 55 d of exposure in the soil that treated with the same concentration of cypermethrin(4~6 mg·kg^(-1)),the concentration of cypermethrin in Amynthas cortices was measured to be 0.34~0.73 mg·kg^(-1)(wet weight)with biological-soil accumulation factor(F BSA)in the range of 0.85~1.05 using the one-time pollution method,while the concentration of cypermethrin in Amynthas cortices was measured to be 0.86~1.51 mg·kg^(-1) with F BSA between 1.16~1.42 under the multiple-time superimposed condition.Compared with the one-time pollution method,the accumulation of cypermethrin in earthworm and the inhibition to earthworm growth both increased significantly(P<0.05)using the multiple-time superimposed pollution.The research provided theoretical basis and related data for the prevention and control of ecological risk from pesticide pollution accumulated in soil.