摘要
采用室内培养实验方法 ,研究了存在有机酸时pH对镉毒害土壤微生物生物量的影响。结果表明 ,存在一定量有机酸的镉污染土壤中 ,土壤中微生物生物量碳 (Cmic)和氮 (Nmic)随着pH升高而升高 ,其中含胡敏酸的土壤中微生物生物量碳 (Cmic)和氮 (Nmic)明显比含低分子量有机酸 (柠檬酸、酒石酸、乙酸、草酸 )的土壤增加的快 ,土壤中微生物生物量碳氮比 (Cmic/Nmic)随着pH升高而降低 ,表明提高土壤pH可降低镉对微生物生物量的毒性。另外 ,对于施加低分子量有机酸的土壤中 ,pH<6.0时 ,土壤中微生物生物量碳 (Cmic)和氮 (Nmic)比未加有机酸的土壤中微生物生物量碳和氮低 ,说明在低pH状态低分子量有机酸增加镉的毒性 ;而施加胡敏酸的土壤中 ,土壤中微生物生物量碳 (Cmic)和氮 (Nmic)均比未加有机酸的土壤中微生物生物量碳 (Cmic)和氮 (Nmic)高 ,说明胡敏酸降低镉的毒性 ,同时提供氮源。
Effects of pH on toxicity of Cadmium towards soil microbial biomass in the presence of organic acids was studied. The results showed that: in the soils contaminated by Cadmium, the microbial biomass C and N increased with enhancement of soil pH at a given concentration of organic acids, but the ratio of soil microbial biomass C:N decreased with increase of soil pH. The boosted rate was faster in the soils receiving humic acid than that adding low molecular weight organic acids (oxalic acid, acetic acid, citric acid, tartaric acid ), suggesting that increased soil pH decrease the toxicity of Cadmium towards soil microbial biomass. In addition, the values of microbial biomass C and N in the soil added with low molecular weight organic acids were lower than those without addition of organic acids at soil pH<6.0. But the values of microbial biomass C and N in the soil containing humic acid were higher than those without addition of organic acids in all pH range. It meant that low molecular weight organic acids could increase the toxicity of Cadmium at lower pH range and humic acid could decrease the toxicity of Cadmium in soil.
出处
《农业环境保护》
CSCD
2000年第4期236-238,共3页
Agro-Environmental Protection
