汞对土壤酶活性的影响

Soil enzyme activity effected by Hg．

对不同肥力土壤脲酶和转化酶活性受汞影响进行了研究,结果显示,土壤脲酶活性、最 大反应速度Vmax 、Vmax/Km和反应速度常数k与汞浓度呈现显著或极显著负相关关系,表明其 可作为土壤汞污染的生态指标;米氏常数Km则变化较小,表明汞与脲酶作用机理为不可逆竞争 抑制;低肥力土壤脲酶比高肥力土壤脲酶受汞毒害作用更强,当汞浓度分别为6.00和14.79mg/ kg时即达到严重污染;而转化酶对汞的敏感性较差;培养时间对土壤酶与汞浓度间关系影响较 小.

The soil urease and invertase activity effected by Hg was investigated in different fertility soils. The results show that soil urease activity maximum reaction velocity (Vmax, Vmax/Km) and reaction velocity constant k have remarkably negative correlation with Hg concentration so that these can be used as ecological indexes of soil polluted by Hg, Km changes a little indicating that the reaction mechanism of Hg and urease is nonreversible competitive restraint. Urease of low soil fertility is more damaged by Hg than that of high soil fertility, with severe pollution at Hg concentration of 6.00 and 14.79mg/kg respectively; while invertase is less sensitive to Hg than urease. Cultural time has less influence on the relationship of soil enzyme and Hg concentration.