Effects of Cr6+ on soil enzyme activity | Cr6+的土壤酶效应研究

Chinese. 研究Cr6+对不同土壤酶活性的影响，为建立土壤重金属铬污染评价的酶学指标提供依据。以我国主要土壤类型中的酸性红壤、碱性褐土和风沙土不同肥力的土壤为供试土样，采用室内模拟方法，研究添加不同含量Cr6+溶液后，土壤转化酶、纤维素酶、脲酶、碱性磷酸酶、芳基硫酸酯酶和脱氢酶活性的变化规律。添加Cr6+后，随着Cr6+含量的增加，除褐土高肥力和风沙土低肥力土样，其他土样脲酶活性总体呈降低趋势；除了褐土高肥力土样，其他土样转化酶活性总体呈降低趋势；各土样碱性磷酸酶活性的变化规律不明显；Cr6+的加入，明显抑制了土壤纤维素酶、芳基硫酸酯酶、脱氢酶及总体酶活性，通过拟合模型计算得到，代表酸性土壤的红壤Cr6+污染生态剂量（ED10)最小值分别为：纤维素酶186 mg/kg、芳基硫酸酯酶2.6 mg/kg、脱氢酶3.8 mg/kg，代表碱性土壤的褐土和风沙土Cr6+污染ED10分别为：纤维素酶162 mg/kg、芳基硫酸酯酶11.7 mg/kg、脱氢酶8.1 mg/kg。土壤有机质对Cr6+含量具有明显的缓冲作用；pH 对Cr6+的生态毒性有一定影响，不同土壤酶在酸碱性不同的土壤中表现出对Cr6+轻度污染的敏感程度不一致，其中酸性土壤中芳基硫酸酯酶对Cr6+的毒害反应更敏感，碱性土壤中脱氢酶对Cr6+的毒害反应更敏感，2种酶均可作为表征Cr6+毒害的酶指标。

English. Influences of Cr6+ on different soil enzymes activity were studied to provide a fundamental groundwork for foundation of enzymology assessment index of soil polluted by heavy metals. Red soil, cinnamonl, sandy soil, which are main soil types in China, were sampled. By using laboratory simulation method, soil invertase, cellulase, urease, alk-phosphatase, arylsulfatase and dehydrogenase activity were studied under different Cr6+ contents. As Cr6+ content increased, soil urease activity reduced overall except for low fertility cinnamon soil and high fertility sandy soil; Soil invertase activity reduced overall except for low fertility cinnamon soil; Soil alk phosphatase activity did not show identical trend; Soil cellulose, arylsulfatase, dehydrogenase and total enzyme activity reached significant negative correlation with Cr6+ content, ED10 on red soil was 186 mg/kg (cellulase), 2.6 mg/kg (arylsulfatase), 3.8 mg/kg (dehydrogenase), ED10 on cinnamonl soil and sandy soil was 162 mg/kg (cellulase), 11.7 mg/kg (arylsulfatase), 8.1 mg/kg (dehydrogenase). Soil organic matter had buffering effect for pollution by Cr6+, pH had certain influence on eco-toxicity of Cr6+, soil enzyme in different types of soil showed different sensitivity, arylsulfatase in acidic soil was more sensitive but dehydrogenase in alkaline soil was more sensitive, and they both could be index to monitor soils polluted by Cr6+.