环草隆对城市绿地重金属污染土壤有机氮矿化、基础呼吸及相关酶活性的影响

城市土壤重金属和有机污染物复合污染广泛存在,而城市草坪除草剂的应用使城市绿地土壤的农药污染问题成为了新的关注点。为了准确评价城市绿地重金属污染土壤的农药污染生态风险,选择不同重金属污染程度的土壤为研究对象,以土壤有机氮矿化量、基础呼吸以及土壤酶活性为指标,采用室内模拟试验方法,探讨了草坪除草剂环草隆污染对土壤微生物的生态毒理效应。结果表明:(1)土壤有机氮矿化、基础呼吸、芳基硫酸酯酶和碱性磷酸酶对重金属和环草隆污染响应较为敏感,脲酶和蔗糖酶对重金属和环草隆污染不敏感。(2)环草隆浓度为0~1 000 mg·kg~(-1)范围内,和污染较轻的样点N土壤的碱性磷酸酶活性抑制(激活)率的线性相关关系显著,和污染较为严重的样点D和G土壤的芳基硫酸酯酶活性抑制(激活)率的线性关系显著。(3)土壤中环草隆对样点D和G土壤芳香硫酸酯酶活性、对样点N土壤碱性磷酸酶活性抑制(激活)率的EC10分别为568 mg·kg~(-1)、1 306 mg·kg~(-1)(抑制值)和56 mg·kg~(-1)(激活值)、99 mg·kg~(-1),EC50分别为1 901 mg·kg~(-1)、3 806 mg·kg~(-1)、2 321 mg·kg~(-1)。以上研究结果能够为城市土壤重金属和农药复合污染生态风险评价提供基础数据和技术方法。

Effects of Siduron on Organic Nitrogen Mineralization, Basal Respiration and Related Enzyme Activities in Heavy Metal Polluted Urban Soil

Combined pollution of heavy metals and organics in urban soil is ubiquitous. Herbicide such as siduron is frequently used in lawn management and pollution of these pesticides in urban soil has become a new focus. In this research, different heavy metal polluted urban soils were selected to evaluate the ecological risk of siduron pollution based on laboratory simulation experiments. Effects of siduron on soil organic nitrogen mineralization, basal respiration and soil enzyme activities were studied. It was suggested that: (1) The soil organic nitrogen mineralization, basal respiration, arylsulfatase and alkaline phosphatase activities were sensitive to heavy metal and siduron pollution, while urease and invertase activities were insensitive. (2) In the range of siduron concentrations from 0 mg·kg^-1 to 1 000 mg·kg^-1, significant linear correlations were observed between siduron concentrations and the inhibition (activation) rates of alkaline phosphatase activity in slightly heavy metal polluted soil N. Significant linear relationships were also observed between siduron concentrations and the inhibition (activation) rates of arylsulfatase activities in soil D and G which were more seriously heavy metal polluted. (3) The EC₁₀s of the effect of siduron on the inhibition (activation) rates of arylsulfatase activities in soil D and G and on the inhibition (activation) rates of alkaline phosphatase activity in soil N were 568 mg·kg^-1, 1 306 mg·kg^-1 (inhibiting value) and 56 mg·kg^-1 (activation value), 99 mg·kg^-1, respectively. And EC₅₀s were 1 901 mg·kg^-1, 3 806 mg·kg^-1,2 321 mg·kg^-1, respectively. The above results can provide basic data and technical methods for the ecological risk assessment of compound pollution of heavy metals and pesticide in urban soil.