中文摘要：

城市土壤是保护城市环境的一个重要生态屏障，城市土壤的退化过程实质上是其“自我牺牲”地发挥生态服务功能从而导致自身质量下降的过程，因此其自身常常存在各种各样的环境问题。除了压实等物理退化过程之外，多种与人为活动有关的元素的富集、不同程度的重金属和有机污染是城市土壤环境问题最主要的方面。城市土壤重金属污染的主要特点是污染的出现没有明显的空间连续性，污染元素以Cu、Zn、Ph和Hg等元素为主，而其他重金属富集程度相对比较低。在城市发展过程中，重金属污染不只是现代过程，根据城市发展的历史，经常会出现历史污染。城市土壤常含有相对富集的多环芳烃，环数在2～6之间，并以2～4环PAHs为主，说明其具有很强的燃烧来源背景。 迄今为止，城市土壤污染研究主要集中于三个方面：对于城市土壤污染物来源、现状及扩散方式的认识；污染对生态环境和健康的影响和风险评价；城市土壤的良性利用和管理调控手段。退化的城市土壤对水、气环境和生物活动以及人体健康都存在显著的影响，不同的城市功能区土壤在环境质量上有明显的区别。目前对于城市土壤污染的环境容量和临界阈值、污染物质迁移、传播动力学、水土气生交互影响、污染的生物效应等方面有待于更深入和全面的研究，这对建立科学的城市土壤污染风险评估体系、控制城市土壤污染、实现城市土壤的良性管理都具有重要的意义。

英文摘要：

Urban soils act functionally as an ecological screen in protecting urban environment. Their degradation, however, is in essence a process of providing ecological services, such as sink of all kinds of pollutants, at the cost of their own quality. Therefore, as a result, they often come across a variety of environmental problems. Besides physical degradation, such as compaction, enrichment of various elements associated with human activities, heavy metals, and organic pollution are the major problems with urban soil environment. The main features of urban soil contamination are characterized firstly by strong accumulation of so-called ＇ urban elements＇ such as Cu, Zn, Pb and Hg, but less of other heavy metals; and secondly by spatial isolation, which means the contamination is not spatially continuous. During the process of urban development, heavy metal contamination of urban soils happens not only nowadays, but also did in the past, especially when primitive mining and metal processing prevailed. Furthermore, urban soils are often polluted by organic pollutants, especially polycyclic aromatic hydrocarbons （PAHs）, with roadsides and industrial sites being the major vulnerable areas. PAHs therein have normally 2 - 6 rings and predominantly 2 - 4 rings, strongly suggesting their pyrogenic background, including motor vehicles, industrial activities and coal burning. So far, studies on urban soil contamination and other related environmental problems have concentrated mainly on three aspects, firstly source, status and diffusion patterns of urban soil contamination; secondly impact and risk assessment of soil contamination on environment, ecology and biological health; thirdly better use and management of urban soils. More researches are expected in the coming near future on environmental capacity of urban soils, threshold values and dynamics of translocation of these contaminants, interactions between soil, water and organisms, and biological effects of pollution. These studies are important to the establi