镉对土壤秀丽隐杆线虫的毒性效应

Toxic effects of cadmium on Caenorhabditis elegans in soils

为明确镉(Cd)对土壤无脊椎动物线虫的毒性效应及不同类型土壤中Cd的毒性差异,以生长量、生育率和繁殖量为评价终点,研究江西鹰潭红壤、江苏苏州水稻土、吉林长春黑土3种土壤中外源Cd对模式生物——秀丽隐杆线虫(Caenorhabditis elegans)的毒性效应。结果表明:以3种土壤总Cd含量推导出的Cd对秀丽隐杆线虫的生长毒性的EC50(半数效应浓度)分别为54.37、197.54 mg·kg^(-1)和287.02 mg·kg^(-1),对生育毒性的EC50分别为7.07、77.41 mg·kg^(-1)和103.09 mg·kg^(-1),对繁殖毒性的EC50分别为5.75、13.84 mg·kg^(-1)和85.94 mg·kg^(-1)。通过毒性阈值可知,线虫的评价终点对Cd毒性的敏感性由高到低分别为繁殖、生育、生长。相关性分析表明,土壤pH、阳离子交换量、有机质、碳酸钙和锰氧化物含量是影响土壤中Cd毒性的主要因素。基于有效态Cd含量推导得出3种土壤中的Cd毒性阈值与基于总Cd含量的毒性阈值相比差异缩小,说明有效态Cd含量能够更好地解释不同土壤中Cd毒性的差异。

To determine the toxic effects of cadmium(Cd)on soil nematodes and the differences of Cd toxicity in different soils,the toxic effects of Cd on the model organism Caenorhabditis elegans were assessed in three soils(red soil in Yingtan,Jiangxi;paddy soil in Suzhou,Jiangsu;and black soil in Changchun,Jilin)using growth,fertility,and the number of offspring as evaluation endpoints.The median effect concentration(EC50)values,expressed as the measured concentration of total Cd,for the growth of C.elegans,were 54.37,197.54 mg·kg^(-1),and 287.02 mg·kg^(-1),respectively.The EC50 values for C.elegans fertility were 7.07,77.41 mg·kg^(-1),and 103.09 mg·kg^(-1),respectively,and those for average number of offspring were 5.75,13.84 mg·kg^(-1)and 85.94 mg·kg^(-1),respectively.The results showed that the number of offspring was a more sensitive evaluation endpoint than growth or fertility.Correlation analysis showed that soil pH,cation exchange capacity,organic matter,calcium carbonate content,and manganese oxide were the main factors affecting Cd toxicity in soil.Based on the CaCl_(2)-extracted Cd concentration,the differences in the Cd toxicity thresholds of the three soils were determined and indicated that the available Cd concentration may better explain the differences in Cd toxicity in different soils.