功夫菊酯与镉复合污染对土壤微生物和镉生物可利用性的影响

Impact of Combined Cyhalothrin-Cd Pollution on Soil Microbes and Bioavailability of Cd

为探讨菊酯类农药和镉复合污染对土壤微生物功能和镉生物有效性的影响,分析了功夫菊酯和镉单一及复合作用下土壤微生物碳、呼吸率和酶活性的变化;同时采用同位素标记和薄膜扩散梯度(diffusive gradients in thin-films,DGT)技术分析了土壤微生物群落抗性和镉的生物有效性。结果表明,镉在复合污染中起主导作用,但功夫菊酯与低浓度镉的复合作用可协同促进微生物活性;功夫菊酯能促进微生物群落对镉的抗性,提高镉的生物可利用性,并可能提高镉在植物中的累积。

To assess the joint impact of cyhalothrin and cadmium on soil microbial activity and bioavailability of Cd,soil samples were collected from a polluted field for analysis of changes in microbial biomass,respiration,enzymatic activity,pollution induced community tolerance( PICT),as well as bioavailability of Cd. For determining the latter two indices,the isotope-labeling and DGT( diffusive gradients in thin-films) technologies were used. Results show that soil respiration rate increased when 2 mg·kg-1Cd was amended into the soil,but decreased when 10 mg·kg-1Cd was. The amendment of both cyhalothrin and a low level of Cd stimulated soil biomass and respiration. Soil catalase,urease and alkaline phosphatase responded differently in activity to Cd and cyhalothrin. Urease was inhibited by Cd and revived to some extend when cyhalothrin was added,whilst alkaline phosphatase was inhibited in the initial 30 days and revived till the 60 th day.The pollution of cyhalothrin alone did not show any PICT effect,however,the combined pollution elevated PICT to Cd,as well as bioavailability of Cd represented by DGT concentration. All the findings suggest that Cd in the combined pollution plays an essential role in affecting the studied indices,but the stimulating effects on soil microbial activity are synergistic ones when pyrethroidis coupled with a low level of Cd. CHT could increase PICT to Cd as well as bioavailability of Cd,which should be considered in the issue of food safety.