基于GIS的农业土壤镉污染时空演变特征

The spatial-temproal Evolution Characteristic of Cd Pollution in the Agricultural Soil Based on GIS

[目的]研究农业土壤中镉(Cd)污染时空演变特征。[方法]以湖南省浏阳市小溪河流域为研究区域,在研究区内采集土壤样本并测定不同土层深度土壤中的Cd含量,利用不同评价标准与评价方法对农业土壤中的Cd污染状况进行评价,同时借助地统计和GIS空间插值方法,以可视化的方式对研究区内土壤中Cd含量的空间分布状况进行综合分析。[结果]土壤中Cd含量不论是以国家二级标准还是以自然背景值为参考评价标准,研究区域浅层耕地层0~10 cm土壤中Cd含量均超过污染指标,说明浅层耕地层受人类活动干扰较大。[结论]该地区农业土壤中主要Cd污染来源为磷肥中的Cd,这对该区域水库水源地的水质产生潜在风险。

[ Objective ] To study the spatial-temproal evolution characteristic of Cd pollution in the agricultural soil. [ Method ] Taking Xiaoxi river basin of Liuyang in Hunan Province as the study area, soil samples were collected according to the soil depth for determination of cadmi- um content in the soil. Using different evaluation standards and methods, cadmium pollution in agricultural soil was evaluated. With the aid of statistical and GIS spatial interpolation method, spatial distribution of soil cadmium content were analyzed within the scope of the study area in the form of visual. [ Result ] The result showed that reference criteria of the soil cadmium content using the national secondary standard or the natural background value evaluation standard, the heavy metal cadmium content in the shallow layer from 0 to 10 cm depth cultivated soils ex- ceeded the pollution index, which indicated in shallow layer soil interference by human activities was larger. [ Conclusion] Major source of cadmium pollution is the cadmium in phosphate fertilizer, it results in enormous potentially risky to water quality.