Hg的土壤酶效应初步研究

采用土壤酶对汞生态毒性进行研究,在理论和实践上具有重要意义。通过室内模拟试验,针对我国几种主要类型土壤(黄褐土、风沙土、塿土和红壤)中影响土壤碳、氮、磷物质循环和微生物活性的土壤转化酶、脲酶、碱性磷酸酶、脱氢酶与Hg的关系进行了探讨。结果表明,Hg抑制土壤碱性磷酸酶、转化酶活性,但规律性不明显;土壤脲酶低浓度时激活,高浓度抑制;土壤脱氢酶和总体酶活性受到抑制。Hg浓度与脲酶、脱氢酶、总体酶活性间达显著或极显著负相关关系,揭示出其在一定程度上可表征土壤Hg污染的程度,其中尤以总体酶活性结果最优;计算Hg轻微污染时的ED10值0.0005～0.59mg·kg-1。土壤有机质和pH对二者关系具有重要影响。

Impact of Mercury on Soil Enzyme Activity

Mercury(Hg) is one of heavy metals which can lead to serious environment pollution.It is of great importance in terms of theory and application to investigate the eco-toxicity of Hg on soil enzyme activity.This article used laboratory simulation methods to explore the relationships between Hg and soil urease,alkaline-phosphatase,invertase,and dehydrogenase which play a significant role in the cycles of carbon,nitrogen,phosphate and microbiological activity using four representative soils including cinnamon,sandy soil,lou soil,red soil.The results showed that Hg could inhibit the activities of soil alkaline-phosphatase and invertase without evident regularity.Hg could substantially inhibit soil urease activity at high concentrations,while slightly increased soil urease at low concentrations.Similarly,Hg could dramatically inhibit soil dehydrogenase activity and the total enzyme index(TEI).Significantly or highly significantly negative correlations existed between Hg and soil urease,dehydrogenase,and TEI.Therefore,they could be used as indicators to evaluate Hg pollution in soils;especially TEI,as an overall index parameter,could be used other than individual indicators.The critical values of ED10 for all soils were among 0.000 5 mg·kg-1 and 0.59 mg·kg-1.Both soil organic matter and pH affected the value of ED10.