不同相伴阴离子对镉污染红壤的微生物活性影响

通过外加醋酸镉和氯化镉的室内培养试验研究了相伴阴离子对镉污染红壤微生物活性的影响。结果表明 ,在相同镉浓度下相伴OAc- 对镉污染红壤的微生物生物量碳、基础呼吸和代谢商以及脲酶和酸性磷酸酶活性的抑制作用大于相伴Cl- ,统计分析显示 ,镉相伴OAc- 与Cl- 除对红黄泥的代谢商未达明显影响外 ,对供试红壤的其它微生物活性指标均达到显著差异 (p <0 0 5 )。用醋酸镉处理的土壤有效态镉含量明显高于氯化镉处理。钾盐试验结果表明 ,相伴OAc- 与Cl- 对土壤微生物活性没有产生明显抑制作用 ,OAc- 甚至还存在一定的刺激效应。可见 ,相伴OAc- 对镉污染红壤的微生物毒害作用大于相伴Cl- ,其直接原因可能是用醋酸镉处理的生物有效性镉明显高于氯化镉处理所致。

INFLUENCE OF ACCOMPANYING ANIONS ON MICROBIAL ACTIVITIES IN RED SOILS POLLUTED WITH CADMIUM

A laboratory incubation experiment was conducted to evaluate the influence of accompanying anions on microbial activities in red soils polluted with cadmium. The results indicated application of cadmium as cadmium acetate markedly inhibited the soil microbial biomass, basal respiration, urease and acid phosphatase activity compared to cadmium applied as cadmium chloride at all cadmium levels. T-test showed that soil microbial biomass, basal respiration, urease and phosphatase activity were significantly different between red soils contaminated with cadmium acetate and chloride except for the metabolic quotients (qCO 2) in red clayey soil. Similarly, there were significant effects of cadmium with different anions on available cadmium contents in red soils after incubation. The available cadmium contents in red soils polluted by cadmium acetate were more than those by cadmium chloride. Another laboratory incubation experiment was carried out to argue the effect of associated anions on microbial activities in red soils added with potassium both acetate and chloride. Its results demonstrated that accompanying acetate anion can enhance soil microbial activities, but associated chloride anion has no remarkable effect on soil microbial activities. Thus it can be seen that difference of available cadmium contents which were resulted in by accompanying anions could be one of factors determining their relative toxicity to the soil microbial activities.