Toxicity Effects And Ecological Thresholds Of Antimony To Soil-Dwelling Caenorhabditis Elegans

The wide application of antimony in human production leads to the increase of antimony concentration in soil environment.Appropriate soil environmental quality standards are needed to guide the risk control of antimony pollution.The standards being implemented have defects,such as not taking into account the differences in soil properties and the potential ecological risks of pollutants to soil invertebrates,which cannot provide strong support for the risk control of soil antimony pollution in China and need to be further revised.To ensure the scientific of the revision work,the threshold research on the toxicity of exogenous trivalent antimony to soil invertebrates needs to be further promoted.This study explored the toxicity of trivalent and pentavalent antimony to model organism Caenorhabditis elegans in 9 typical soils by using growth,fertility and reproduction as toxicity evaluation endpoints.Through Pearson correlation analysis,the soil properties affecting the exogenous trivalent antimony toxicity and aging factor were determined.Multiple linear regression analysis was used to construct the prediction model of exogenous trivalent antimony toxicity and aging factors in soils.In this study,the international standard ISO 10872 was used as the guide of the experiment.The experimental results show that:（1）The growth,fertility and reproduction toxicity of exogenous trivalent and pentavalent antimony shows significant differences in 9 types of soil.The EC₅₀（median effect concentration）of exogenous trivalent antimony for the growth,fertility,reproduction toxicity of C.elegans ranged from 785～2514,546～1557 and 976～3334 mg·kg^-1,respectively.The sensitivity of evaluation endpoints to exogenous antimony toxicity is as follows:reproduction>fertility>growth.The toxicity of exogenous pentavalent antimony was lower than that of trivalent antimony,and there was no significant growth,fertility and reproduction toxicity to C.elegans.（2）Based on the total antimony concentration,the maximum difference between the thresholds of exogenous trivalent antimony toxicity to nematode growth,fertility and reproduction was 3.4,3.2 and 2.9 respectively.Based on the Na₂HPO₄-extracted antimony concentration,the maximum difference between the thresholds of exogenous trivalent antimony toxicity to nematode growth,fertility and reproduction was reduced to 2.2,2.5 and2.5 respectively.The concentration of Na₂HPO₄-extracted antimony could express the toxicity differences in different soils better.（3）Pearson correlation analysis showed that cation exchange capacity,organic matter and amorphous iron oxides were main soil properties affecting the toxicity of exogenous trivalent antimony.The results of multiple linear regression analysis showed that cation exchange capacity,organic matter and total iron content could explain the growth,fertility and reproduction toxicity of exogenous trivalent antimony to C.elegans better.（4）The aging process reduced the toxicity of exogenous trivalent antimony to C.elegans in soils.With the aging process,the concentration of Na₂HPO₄-extracted antimony and the proportion of trivalent antimony in total antimony gradually decreased,which reduced the biological toxicity of exogenous trivalent antimony.Pearson correlation analysis showed that p H,cation exchange capacity,total manganese,total aluminum and amorphous manganese oxides and free manganese oxides were main soil properties affecting the aging process of exogenous trivalent antimony.