Health risk assessment and spatial distribution characteristics of heavy metal pollution in rice samples from a surrounding hydrometallurgy plant area in No. 721 uranium mining, East China

Abstract

Abstract In order to detect pollution status and spatial distribution characteristics of heavy metals in rice samples from hydrometallurgy plant area in No. 721 uranium mining, East China, a total of 44 rice samples were collected to be analyzed for obtaining heavy metal contents and assessing the pollution degrees of Pb Zn Cu Cr Cd As and U elements by using methods of Nemerow index and potential ecological risk index. The spatial distribution models and health risk evaluation of As and U elements were constructed with Kriging interpolation and carcinogenic risk evaluation model, respectively. The contents of Pb Zn Cu and Cr in rice samples are all lower than the China national food standards, indicating no excess and contamination. The average contents of As (321.86\u202fng·g−1), Cd (53.67\u202fng·g−1) and U (1.39\u202fng·g−1) from the analytical samples exceed standard rates are up to 97.73%, 4.55% and 79.55%, respectively. Single factor pollution indexes of As and U are classified into moderate pollution. And comprehensive pollution index of analytical rice samples are categorized as slight level with characteristics of slight ecological risk, which is mainly caused by U element. Simple Kriging spherical model, the best interpolation model of U contents, presents high U contents in rice samples that are mainly distributed in the south, east and northeast of the study area. Those distribution characteristics are mainly controlled by human activities such as ore transportation, drainage pipe leakage and so on. Meanwhile, the high As contents of rice samples are located in the middle and northwest on the basis of Ordinary Kriging exponential model. For CRi index of consuming rice with high contents of U element, children are more vulnerable to suffer from a high level of the risk than adults. In addition, the TCR index for both of them are higher than the maximum risk interval recommended by US EPA, suggesting there may be certain carcinogenic risk.