城市土壤生态功能演变及其生态环境效应.doc

城市土壤生态功能演变及其生态环境效应 摘要：城市是人类生产与生活所在的主要空间区域。在城市化过程中，土地利用类型急剧变化，造成一系列生态环境条件的改变。城市土壤在强烈的人为活动影响下不断恶化，主要表现在物理和化学性质两个方面，如土壤容量增加、持水孔隙降低、土壤富营养化和重金属积累等。城市土壤的生态功能也发生着明显演变，即以主要维持植物生长的功能向以容纳、缓冲、净化污染的功能为主转变。该转变对城市生态系统的其他三个要素—大气、水、生物，产生一系列影响，如大气颗粒物增多、地表水污染严重和植物重金属污染等。因此，有必要对城市土壤生态功能演变及其生态环境效应展开系统的研究，丰富城市土壤研究体系，为城市土壤管理、城市生态发展提供理论依据。 关键词：城市化 城市土壤 城市土壤污染 生态功能 生态环境效应 Change of ecological functions in urban soil and its eco-environmental impacts Abstract: City is the main spatial area where people produce and live. In the process of urbanization, the land use style has a dramatic change that has caused a series of changes of eco-environmental conditions. Due to the impacts of heavy human activities, urban soil has gradually deteriorated, mainly showing in the two aspects of characters of physics and chemistry, which include increasing soil bulk density, reducing water retention porosity, soil eutrophication,　heavy metal accumulation and so on. Ecological functions of urban soil have changed obviously too, i.e,, from that of sustaining plant growth to that holding, buffering and purifying pollution. This change has a series of impacts on the other three factors of urban ecological system which contain atmosphere, water, biology, in instance, increasing atmospheric particles, serious upper water pollution and plant heavy metal pollution, and so on. So, it is essential to conduct a systemic study on change of ecological functions of urban soil and its eco-environmental impacts in order to enrich the research system of urban soil and provide the basic theory for urban soil management and urban ecological development. Key words: civilization, urban soil, urban soil pollution, ecological function, eco-environmental impacts 城市是物质、能量和信息高度集中的场所，是人类生产与生活所在的主要空间区域。城市化是工业化的产物。自20世纪的第三次工业革命以来，全世界城市化进程不断加快，尤其是发展中国家的城市化更是迅猛。目前世界上一半以上的人口生活在城市，中国的城市人口比例也已经超过了40％，但是全球城市面积占陆地面积不到2％。在局部的区域内集中了众多的物质、高能量以及各种信息，城市化给人类带来巨大财富的同时，也造成了严重的城市环境问题。城市是一个社会一经济一自然复合生态系统，也是一个极不稳定的人工生态系统【1】，它继承一般生态系统的特征，但又别于自然生态系