徐州城市森林土壤重金属污染评价研究
Research on Evaluation of Heavy Metals Pollution in Urban Forest Soil of Xuzhou

城市森林是林学家、生态学家为了提高城市绿地的生态功能而提出的城市绿化生态建设措施，重金属污染已成为全球共同关注的热点问题。以徐州市城市森林土壤为研究对象，对不同城市森林类型和不同区域森林土壤重金属污染进行综合评价。结果表明，徐州市城市森林土壤表层的5种重金属Cu、Cd、Zn、Pb、Cr含量均高于中国土壤元素背景值，其中Cd的污染程度较高，污染较严重，Cu、Zn、Pb、Cr无污染或轻度污染；从综合污染指数看，6种城市森林类型土壤重金属污染排序：悬铃木 + 泡桐混交林(0.92) < 香樟林(1.07) < 雪松林(1.14) < 侧柏林(1.35) < 刺槐林(1.46) < 毛白杨 + 银杏混交林(2.06)；不同区域城市森林土壤中同一种重金属污染程度有所不同，城市中心区域森林土壤Cu、Cd、Zn、Pb、Cr单项污染指数均分别高于城市边缘区和城市郊区，而城市边缘区与城市郊区则差别不明显；不同区域土壤重金属污染程度由高至低排序：城市中心区 > 城市边缘区 > 城市郊区。其研究结果为不同功能区域城市森林土壤重金属污染现状水平提供科学参考。
Urban forest, an urban greening ecological construction measure, was put forward by forest scien-tists and ecologists so as to improve the ecological function of urban green space. Taking the urban forest soil in Xuzhou as research object, comprehensive evaluation of heavy metal pollution was car-ried out from different types of urban forest and forest soil. The results show that the content of 5 kinds of heavy metal Cu, Cd, Zn, Pb, and Cr in Xuzhou urban forest soil was higher than China soil element background values. The pollution of Cd presents the most prominent, while the pollutions with Cu, Zn, Pb, and Cr are free or mild contamination level. From the comprehensive pollution index, the rank of six types of urban forest soil heavy metal pollution is plane tree and paulownia mixed forest (0.92) < camphor forest (1.07) < cedar forest (1.14) < Platycladus orintalis forest (1.35) < locust forest (1.46) < Chinese white poplar bark and ginkgo mixed forest (2.06). The degree of contamination of the same kind of heavy metal pollution in urban forest soil is diverse in different regions, the single pollution indexes of forest soil with Cu, Cd, zinc, Pb, and Cr in urban central areas are higher than those of urban fringe and suburban areas respectively, and the difference of urban fringe area and the city suburbs is not obvious. The pollution levels of the soil heavy metal in differ-ent regions can be ranked as: urban central areas > edge area of city > city suburbs. The results have provided certain reference for the level of heavy metal pollution in the city.