Heavy metal accumulation and its spatial distribution in agricultural soils: evidence from Hunan province, China

< 0.05) higher than their background values and they were not distributed evenly across the Hunan province; the content of each heavy metal in eastern Hunan (including the cities of Yueyang, Changsha, Zhuzhou, and Chenzhou) was higher than that of other regions. The exceeding standard rate (the ratio of surveyed content to the background value) for Cu, Cd, As, and Hg had strongly positive spatial correlation, whereas Zn and Ni presented a negative spatial correlation. Overall, the higher exceeding standard rates of the 8 heavy metals were mainly distributed in the highly industrialized cities such as Changsha, Zhuzhou, Xiangtan, Chenzhou, and Hengyang, thus more attention should be paid to such areas to manage soil pollution.