基于GIS的城市镉元素空间分布特征及其污染评价

以内江市城区为研究区，以GIS软件为平台，利用单因子污染指数法结合地统计方法，分析了内江市城市土壤镉元素空间分布特征及污染水平。结果表明:内江市土壤镉元素含量偏高，污染较重。总体来看，0—15 cm镉含量（0.823 9±0.429）mg/kg]大于15—30 cm镉含量（0.637 5±0.306）mg/kg]，均高于国家二级标准值0.3 mg/kg。方差分析表明，不同土地利用类型同国家二级标准值之间镉元素含量差异显著。同时，表层的污染程度较深层大，表层中度和重度污染面积占95.07%，污染较重；深层轻度污染和中度污染面积占82.26%，污染较轻。

Spatial Distribution Characteristics of Cd and Evaluation on Cd Pollution Situation in Urban Area Based on GIS

We selected Neijiang City proper as the study area, used GIS and combined single-factor pollution index method with statistical method to analyze the spatial distribution characteristics of soil Cd in Neijiang City. The contents of Cd in soil and pollution levels in Neijiang urban area are high, on the whole, Cd content of the topsoil (0—15 cm) is (0.823 9±0.429) mg/kg, which is greater than that in the deep soil (15—30 cm) where the content is (0.637 5±0.306) mg/kg, and they are higher than the national standard value in soil (0.3 mg/kg), respectively. The contents of Cd are different land-use types vary greatly. Meanwhile, the pollution degree of top soil is more severer than deep soil, and the moderate and severe pollution occupies 95.07% in surface; however, areas of slight and moderate pollution in deep soil occupy 82.26%, indicating the less contamination.