人工封闭对城市土壤功能的影响研究进展

Effects of anthropogenic soil sealing in urban areas on soil function:A review

随着全球城市化的快速发展,城市生态系统研究已受到人们的广泛关注。土壤作为城市生态系统的一个重要组成单位与功能载体,其功能与质量已受到城市化的冲击和影响。由人类活动(如房屋建筑、道路建设等)引起的土壤封闭是城市土壤的一个重要特征。与自然土壤封闭相比,人工封闭土壤严重地阻碍了城市土壤与外界环境的物质能量交换,限制了土壤功能的实现,成为导致土壤质量退化的重要因素。研究人工封闭对城市土壤功能的影响有利于更全面认识城市化的生态环境效应。本文介绍了城市土壤人工封闭的概念、主要特点及其与传统自然土壤封闭的异同;综述了人工封闭对城市土壤水分运动、土壤与环境间气体与能量交换、生物多样性与行为以及粮食安全影响等方面取得的研究进展。目前城市封闭土壤研究仍处于起步阶段,仅在个别城市开展过相关研究,且主要围绕人工封闭对城市环境与土壤的表观影响,对封闭后土壤性质的变化及其机制研究仍很缺乏。未来仍需在更多城市开展系统调查以获取基础数据,需着重研究城市封闭土壤中污染物的赋存、迁移、转化,封闭后土壤碳氮固持能力的变化,以及土壤微生物性质的变化,同时要创新研究方式和研究方法,为加强城市生态系统研究、实现城市可持续发展提供科学依据。

There has been increasing interest in the study of urban ecosystem, with rapid urbanization around the world. As an important component of the urban ecosystem, urban soils are also severely impacted by urbanization, which are interpreted by the changes in soil function and quality. Usually, large areas of urban soils are covered by housing, roads, or other construction work, which heavily perturbs soil’s function. That is artificial soil sealing resulting from anthropogenic activities, and is different from the soil sealing in farmland and forest, or those in other natural soils. Generally, the soils under impervious surfaces in urban areas are impacted more severely by anthropogenic activities than uncovered soils, implicating significant alternations of soil function and quality occurring in the urban sealing soils. Unfortunately, the soil characteristics and function beneath impervious surfaces is not well established, giving difficulties for understanding the net influence of urbanization on soils. Given that greater damaging impact on soil function is exerted by the artificial soil sealing versus natural soil sealing, study on the urban soil sealing is critical to advance our understanding of urban ecosystem. Here, we review recent research on the impact of artificial soil sealing in urban areas on soil functions, including water movement, gas and energy exchange, as well as biodiversity and activity. Overall, the artificial soil sealing in urban areas has negative impacts on soil function and the urban environment, mainly due to that the impervious surfaces can hamper the exchange of material and energy between soil and other environmental compartments. To date, there is not adequate research focusing on the characteristics of the soil beneath impervious surfaces mainly due to inaccessibility. More studies in relation to urban impervious-covered soils, therefore, need to be developed in various cities around the world to obtain a comprehensive knowledge of the influence of urbanization on the ecosystem. Four priority areas for future research are proposed： （1） investigating the changes in forms and accumulation of some pollutants （e.g., heavy metals and polycyclic aromatic hydrocarbons） after soil sealing; （2） focusing on carbon and nitrogen transformation in the artificial sealing soil; （3） promoting the study of micro-biodiversity of the soils underneath impervious surfaces; and （4） developing new research methods for urban impervious-covered soils.