• 关键词：城市化  土壤重金属  空间分布  建筑密度  道路密度

• 基金项目：国家自然科学基金项目（No.41601311）；四川省教育厅重点项目（No.17ZA0308）

• 安吉
• 四川农业大学资源学院, 成都 611130

• 李婷
• 1. 四川农业大学资源学院, 成都 611130;2. Center for Spatial Information Science and System, George Mason University, Fairfax, VA22030, USA

• 张世熔
• 四川农业大学环境学院, 成都 611130

• 郑雯文
• 四川农业大学资源学院, 成都 611130

• 狄黎平
• Center for Spatial Information Science and System, George Mason University, Fairfax, VA22030, USA

• 郭鹏
• 四川农业大学资源学院, 成都 611130

• 摘要：城市化导致城市面积扩张和土地利用方式改变，从而影响了土壤重金属空间分布.本文以成都-温江这一典型"中心城-郊区-卫星城"梯度带为研究区，探讨绿地表层土壤重金属Cu、Pb和Zn的空间分布特征及其影响因素，以期为城市土壤重金属污染治理提供帮助.结果表明，研究区内土壤Cu、Pb和Zn含量均值分别为47.77、39.98和89.65 mg·kg^-1，其中土壤Cu和Pb含量均值超过土壤背景值.3种重金属含量在"中心城-郊区-卫星城"梯度带呈现先降低后增加的趋势.方差分析表明，区内不同绿地类型土壤Cu和Zn含量差异显著（p<0.05），Pb含量在各个绿地类型下无显著性差异（p>0.05）；回归分析显示3种重金属含量随距城市中心距离增加而极显著降低（p<0.01）；缓冲区分析表明，土壤Cu、Pb和Zn含量受局部范围内的建筑密度和道路密度影响，且随局部范围内建筑密度和道路密度的增加而显著增加（p<0.05）.逐步回归分析显示，土壤Cu含量主要受建筑密度影响，Pb含量主要受道路密度和绿地类型影响，Zn含量则受绿地类型、道路密度和建筑密度的共同影响.研究结果显示城市化造成土壤重金属在一定程度上累积，距城市中心距离、绿地类型、建筑密度和道路密度均会影响土壤重金属的空间分布.

• Abstract：Urbanization results in rapid expansion of construction land area and changes of land use types over the past decades, which greatly influences the spatial distribution of soil heavy metals around the city area. In this paper, the spatial distributions of soil heavy metals including Cu, Pb and Zn were studied in a typical "center city-suburban-satellite city" gradient zone of western Chengdu City of Sichuan Province, China, aimed to provide useful information for effectively prevention of soil heavy metal pollution. The results showed that the average concentrations of Cu, Pb and Zn in soils were 47.77, 39.98 and 89.65 mg·kg^-1, respectively, and the values of Cu and Pb concentrations in soil were higher than the background values. The concentrations of all the three soil heavy metals decreased from center city to suburban, and then increased from suburban to satellite city. The concentrations of soil Cu and Zn showed significant differences among different green space types (p<0.05), while the concentrations of soil Pb showed no significant difference (p>0.05). The results of regression analysis indicated that the concentrations of the three heavy metals in soils significantly declined with the increasing distance from the city center (p <0.01). The buffer zone analyses illustrated that the concentrations of Cu, Pb and Zn in the soils were positively correlated with the road density and building density in local area (p<0.05). Stepwise regression analyses exhibited that road density was the determinants governing soil Cu concentrations, road density and different green space types were the main controlling factors for soil Pb, and the concentrations of soil Zn were together controlled by the above three factors. In conclusion, urbanization has led to the accumulation of heavy metals, and the distance from urban centers, different green space types, construction density and road density determined the spatial distribution of heavy metals in the process of urbanization.

• Key words：urbanization  soil heavy metal  spatial distribution  construction density  road density

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