Study on the Effect of Exogenous Organic Acid on Zn Uptake in Earthworm (Eisenia fetida) and Ecological Toxicity
In order to study whether exogenous organic acid can enhance the uptake of heavy metals by earthworms and aggravate the harm to the soil ecosystem,this paper adopted simulated soil solution test and selected Zn as target pollutant,to investigate the effects of organic acids (acetic acid,oxalic acid,citric acid and EDTA) on Eisenia fetida exposed to different concentrations of Zn.The results showed that,organic acids had obvious detoxification effect to Zn toxicity of Eisenia fetida,with the detoxification effect increasing in the order of acetic acid＜oxalic acid＜citric acid＜EDTA,which took the form of the decreasing mortality of earthworms.When the earthworms were exposed to the Zn solution of the concentrations of 5 mg/L,10 mg/L and 15 mg/L,the mortalities of earthworms were 20％,55％ and 83.75％,respectively,and with the increase of organic acids concentration,the earthworm mortality reduced.The contents of antioxidant enzymes (SOD and CAT) and malondialdehyde (MDA) reduced with the increase of organic acid concentration,and different organic acids had different effects on SOD and CAT,but the content of MDA decreased obviously,even close to the control level.The detoxification mechanisms of organic acids for Zn should be related with their inhibition capacity of Zn enrichment in earthworms and complexation effect,which changed the subcellular distribution of Zn,decreasing the ratio of E component and increasing the ratio of H component.Thus,the organic acids reduced the toxicity of the heavy metal.Therefore,organic acids play an important role in the control of biological availability of heavy metals.
国家科技期刊平台
NSTL
万方数据
维普
