Li Yong, Zhou Yong-Zhang, Zhang Cheng-Bo, Dou Lei, Du Hai-Yan, Lin Xiao-Ming, Fan Rui, Du Min, He Xiang
Department of Earth Science, Sun Yat-Sen University, Guangzhou 510275, China.
Huan Jing Ke Xue. 2010 Jun;31(6):1617-23.
The index of local Moran's I is a useful tool for identifying hotspots of soil Ni and Cr, and for classifying them into spatial clusters and spatial outliers. To identify hotspots of vegetable soils Ni and Cr in high-incidence area of liver cancer, Shunde area of Foshan City, Pearl River Delta Economic Zone, 208 topsoil samples were collected from vegetable fields to measure the contents of nickel (Ni) and chromium (Cr). The results showed that the mean concentrations of two heavy metals Ni, Cr were 33.21 mg/kg, 80.84 mg/kg, respectively, Which were 130%, 60% higher than their soil background values of Guangdong Province, respectively. Generally, Ni is partly accumulated in soil but the accumulation of Cr is not obvious at all. The local Moran's I of Ni and Cr was calculated using 3 000, 6 000, 9 000 m as distance bands, respectively. The hotspots of Ni and Cr elements in soils were identified by local Moran's I which computed based on 6 000 m; "individual hotspots" are in the north which were affected by anthropogenic factors; "regional hotspots" are in the south which were controlled by parent materials. Moreover, the distributions of "regional hotspots" of Ni, Cr are the same as that of the highest mortality rate of liver cancer, this consistence could come up with a research direction that could reveal environmental etiologic factors of liver cancer.
局部莫兰指数（Local Moran's I）是识别土壤镍和铬热点区域以及将它们划分为空间聚类和空间离群值的有用工具。为了识别珠江三角洲经济区佛山市顺德区肝癌高发地区蔬菜土壤中镍和铬的热点区域，从菜地采集了208份表层土壤样本，以测量镍（Ni）和铬（Cr）的含量。结果表明，两种重金属镍、铬的平均浓度分别为33.21mg/kg、80.84mg/kg，分别比广东省土壤背景值高130%、60%。总体而言，镍在土壤中有一定程度的积累，但铬的积累并不明显。分别以3000m、6000m、9000m作为距离带计算镍和铬的局部莫兰指数。基于6000m计算的局部莫兰指数识别出了土壤中镍和铬元素的热点区域；“单个热点”位于北部，受人为因素影响；“区域热点”位于南部，受母质控制。此外，镍、铬“区域热点”的分布与肝癌最高死亡率的分布相同，这种一致性可能为揭示肝癌的环境病因提供一个研究方向。
