湘江流域主要支流土壤Cd污染空间分布与相关性

针对土壤Cd污染超标问题，开展流域尺度下的土壤Cd空间分布与相关性分析，选定土壤污染热点区域——湘江流域作为研究对象，以流域内主要支流的汇水范围作为分析单元，研究各支流流域土壤w（Cd）的空间分布特征及空间相关性.结果表明:湘江流域上、中、下游各支流流域之间表现出明显的空间差异性，土壤w（Cd）平均值表现为中游支流（0.29 mg/kg）>下游支流（0.19 mg/kg）>上游支流（0.17 mg/kg）；湘江流域的土壤w（Cd）分布与相关污染企业位置相关性很高，沩水、浏阳河、渌江、涟水、洣水、蒸水、耒水、舂陵水和灌江流域土壤w（Cd）空间相关性较低（0.626 ≤ R ≤ 0.767），企业位置分布具有明显的聚集性；潇水流域土壤w（Cd）空间相关性（R=0.889）较高，企业分布较为均匀，通过潇水流域的各向异性分析可知，土壤w（Cd）分布与企业分布方向一致.研究显示，湘江流域内土壤w（Cd）分布存在空间差异性，各支流的土壤w（Cd）与相关污染企业的空间分布存在依存关系. 

Spatial Distribution and Correlation of Soil Cadmium Contamination in Xiangjiang River Tributary Basin of China

Because of the diversiform sources of soil contamination, such as the exhaust gas discharged by manufacturers, sewage irrigation, excessive use of phosphatic fertilizers and so on, soil heavy metal contamination is complicated. It has become one of the most serious environmental problems. Soil contamination incidents caused by Cd were reported to be threatful to human health in China. For this reason, we take the Xiangjiang River Basin, where soil heavy metal contamination has received extensive attention, as the research object, and simulate the influence range of the tributary of Xiangjiang River. Then, we carried out soil point layout, sampling and analytical test. Simultaneously, we classified and analyzed the data about polluting firms in research region. It proves that the Cd content in contaminated soil of the upstream tributary of the Xiangjiang River Basin is the lowest (0.17 mg/kg) and the downstream tributary is the second one (0.19 mg/kg), and the Cd content in contaminated soils of the middle reaches is the highest one (0.29 mg/kg). There are obvious differences in Cd content in contaminated soils in different tributaries basin. The result of the spatial autocorrelation analysis and spatial heterogeneity analysis are also different in various tributary basins. The spatial correlation of Cd content in contaminated soils in the Weishui River basin, the Liuyang River basin, the Lujiang River Basin, the Lianshui River Basin, the Mishui River Basin, the Zhengshui River Basin, the Leishui River Basin, the Chonglingshui River Basin and the Guanjiang River Basin are relatively low with R values between 0.626 and 0.767, and the aggregated distribution of enterprises was obvious. The spatial distribution of Cd content in Xiaoshui Basin is relatively high (R=0.889), and the distribution of enterprises is well-distributed. According to the analysis of anisotropy in Xiaoshui Basin, the distribution of Cd content in contaminated soils is consistent with the distribution of enterprises. The research shows that the soil Cd content is obvious differences in different tributaries basin and is related to the spatial distribution of related polluting enterprises in the Xiangjiang River.