土壤酶对重金属污染的响应及指示研究进展

Research Progresses on Soil Enzymes as Indicators of Soil Health and Their Responses to Heavy Metal Pollution

土壤酶在关键元素生物地球化学循环、动植物健康维持、环境污染净化等方面起着不可替代的重要作用,同时还是土壤污染程度评价的辅助指标之一。然而,由于土壤物理、化学和生物学性质的差异,以及研究方法的多样化,导致重金属与土壤酶活性之间的关系十分复杂,阻碍了土壤酶在土壤质量和健康评价中的应用。系统阐述了重金属污染对土壤酶的生态毒理效应,及其对土壤酶催化动力学特征的影响,构建了土壤-重金属-微生物对土壤酶作用的概念模型,并探讨未来的研究趋势和方向。土壤酶活性测定高效、便宜,且对重金属污染敏感,是极具潜力的土壤重金属污染评价的生物学指标,但仅采用土壤酶活性可能高估或低估重金属的生态毒性,加之当前对土壤酶的选择、活性的测定均缺乏统一的标准,致使难以建立重金属毒性阈值与土壤理化性质或土壤重金属有效性之间的定量关系,最终导致土壤酶在土壤污染生态风险评价中存在争议。未来亟需通过新技术和数学模型,深入揭示不同类型土壤中酶对重金属胁迫的响应机理,构建土壤性质与毒性阈值关系的经验模型,可为加强土壤酶在土壤质量和健康评价中的应用提供重要的理论依据。

Soil enzymes play a vital role in the biogeochemical cycling of key elements,maintenance of animal and plant health,and decontamination of environmental pollution.The activities of soil enzymes can be applied in the environmental risk assessment of soil heavy metal pollution.However,the effects of heavy metals on soil enzyme activities varied with soil physicochemical and biological properties and the differences of research methods.Thus,these factors hinder the application of soil enzymes in the assessment of soil health and quality.This study systematically elaborates the eco-toxicological effects of heavy metal pollution on soil enzyme activities and the kinetic characteristics of soil enzyme catalytic reactions.We also constructed a conceptual diagram of soil enzymes in response to soil-heavy metals-microorganisms,proposed and discussed the future trends and directions in soil enzyme in the assessment of heavy metal pollution.Soil enzymes are potential biological indexes for the evaluation of soil heavy metal pollution,because the determination of soil enzyme activity is efficient and cheap,and soil enzyme activity is sensitive to heavy metal toxicity.However,soil enzyme activity may overestimate or underestimate the ecological toxicity of heavy metals as an individual indicator.Furthermore,there is no uniform standard on how to select soil enzyme as a general indicator to assess the toxicity of heavy metals in different soils.Also,it is difficult to establish a quantitative relationship between the ecological doses of heavy metals for soil enzyme activity and soil properties,which led to the arguments about its accuracy and applicability in the ecological risk of heavy metal pollution.Therefore,it is crucial to use new technologies and methods to uncover the reactive mechanisms of enzymes to heavy metal toxicity in different types of soils,and quantitatively analyze the relationship between soil properties and ecological doses of heavy metals based on kinetic parameters.This can strengthen the practical application of soil enzymes in the diagnosis of soil pollution by heavy metals.