腐殖酸存在下镉和铅对土壤脱氢酶活性的影响

采用室内培养试验研究Cd和Pb污染红壤添加不同组分腐殖酸后,其脱氢酶活性的变化,结果表明,红壤遭受镉和铅污染后,脱氢酶活性显著降低,然而腐殖酸特别是胡敏酸的存在能够使脱氢酶活性得到显著回升,说明腐殖酸与重金属的相互作用对重金属污染土壤微生物活性的改善和修复功能,对土壤有一定的去污降毒作用.不同腐殖酸组分的效应大小为:灰色胡敏酸(GHA)>棕色胡敏酸(BHA)>富里酸(FA),表明分子量愈大、芳构化程度愈高的腐殖酸组分,其对重金属的钝化愈强,从而解除土壤重金属对生物毒害的能力愈强.

DEHYDROGENASE ACTIVITY OF Cd AND Pb-CONTAMINATED SOIL IN THE PRESENCE OF HUMIC SUBSTANCES

The change of hydrogenase activity in Cd, Pb-contaminated red soil was investigated after various fractions of humic substances were added. Results showed that when red soil was contaminated by Cd or Pb, its hydrogenase activity significantly dropped. However, humic substance, particularly humic acid fraction, was able to significantly improve hydrogenase activity of red soil, indicating humic substance has amelioration and restoration function on microbial activity, as well as certain detoxification effect on heavy metal-contaminated soil. The increase efficacy for various fractions of humic substance was in the sequence of gray humic acid (GHA) > brown humic acid(BHA) >fulvic acid (FA). It was fully exhibited that the higher the molecular weight and aromaticity of humic substance, the stronger heavy metal was immobilized, so that the biotoxicity of heavy metal in soils was more greatly alleviated.