汞污染对水稻土微生物和酶活性的影响

通过盆栽试验，研究了两种水稻土中不同汞处理的微生物学和酶学效应.结果表明：水稻收获后，除部分土壤的呼吸强度和代谢商随汞处理浓度的增加而持续增加外，不同浓度汞处理后土壤微生物量碳、呼吸强度、土壤脲酶、酸性磷酸酶和脱氢酶均表现为在低浓度汞处理(<2 mg Hg·kg^-1)时升高，而在高浓度汞处理(≥2 mg Hg·kg^-1)时则下降.土壤微生物商是对汞处理比较敏感的微生物学指标.黄红壤不同浓度汞处理的土壤酶活性大于小粉土.对重金属生态剂量ED₅₀进行分析表明，汞对小粉土脲酶活性和黄红壤磷酸酶活性的生态毒性均较强.

Effects of Hg contamination on paddy soil microbial and enzymatic activities.

With pot experiment, the microbial and enzymatic activities in two paddy soils w ere investigated at different Hg2+ loadings. The results showed that a fter harvest, all measured microbiological and enzymological indices including m icrobial biomass carbon, respiration rate, and activities of urease, acid phosph atase, and dehydrogenase in test soils were increased under low Hg treatments (< 2 mg Hg·kg-1) while decreased under high Hg treatments (≥2 mg Hg·kg -1), except the basal respiration and metabolic quotient were partly increased with increasing Hg level. Among the test indices, soil microbial quotient was a microbiological index more sensitive to Hg contamination. The enzymatic activit y in test yellowish red soil was higher than that in test silty loam soil. ED 50 analysis indicated that Hg had a stronger ecological toxicity on soil ure ase in test silty loam soil and on acid phosphatase in test yellowish red soil.