铅污染水稻土的微生物活性

Effects of Lead on Microbial Activities in Paddy Soil

采用盆栽试验方法,研究了受外源铅污染(0￣1 200 mg.kg-1)种植水稻后的青紫泥的微生物量碳、基础呼吸作用、代谢商及土壤脲酶、脱氢酶的变化,分析了外源铅污染的水稻土微生物学特性。结果表明,随培养时间延长,水稻土生物量碳呈下降趋势,基础呼吸作用随铅浓度升高而加强;土壤代谢商随铅浓度升高变化趋势不同;土壤脲酶、脱氢酶活性随铅处理浓度升高明显受抑制;土壤有效铅与土壤微生物生物量碳及土壤脲酶呈显著负相关。

Lead pollution has negative impact on soil organism and soil physical-chemical character. Plants can take up excess Pb from contaminated soil and accumulate in the edible parts of the plant. Lead accumulation in soil can cause contamination of food chains thus posing a threat to the health of human beings. Soil biological and biochemical properties, including soil respiration, microbial biomass and enzyme activity, are considered to be sensitive to environmental stress. These properties have been suggested as indicators of soil quality change. Soil microbial properties indicated degree of soil contamination may be more comprehensive and scientific than soil chemical indexes. An incubation study was conducted using the typical paddy soil in Zhejiang province to understand microbial and biochemical response to lead stress in a paddy soil. External lead （Pb） loading of 0 to 1 200 mg· kg^-1 affected soil basal respiration, microbial biomass carbon, urease and dehydrogenase activity. With increasing Pb loading, soil microbial biomass carbon decreased, soil basal respiration increased and as a result, soil metabolic quotient at high loading （1 200 mg· kg^-1） significantly increased compared with other treatments of Pb. The microbial quotient decreased with increasing Pb loading. The activity of urease markedly declined with increasing Pb loading, dehydrogenase activity slightly increased at low level of Pb （400 mg· kg^-1） and decreased at higher level. Correlation analysis indicated that there were significantly negative correlations between soil biomass carbon and urease activity with available lead content in the soil.