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Characteristics analysis of the heavy metal content in wheat irrigation water systems in Xiaoxian county, China

Zhang Yong, Chen Kungang, Zheng Huiling, Wu Jiaojiao

An integrated approach of pollution evaluation indices, correlation cofficient analysis and box plot analysis was employed to evaluate the intensity and sources of pollution in wheat irrigation water of Xiaoxian county in China. Lead(Pb), cadmium(Cd), chromium(Cr), arsenic(As),mercury(Hg) levels in most of the samples do not exceed the national standards that only Hg level of 3 samples which is Qinglong town,Jiudian town and Dulou town exceed. The average content of Pb, Cd, Cr, As, Hg is respectively 16.33μg/L, 7.29μg/L, 6.69μg/L, 4.45μg/L, 0.41μg/L. Using the method of single factor index and the Nemero index, the quantitative proportion of good level is 65.22% that shows the quality of wheat irrigation water in Xiaoxian county has no harm to agricultural production. The Nemero index (I) shows strong correlations with Hg that the correlation coefficient is 0.946,and gives a better assessment of pollution levels. The key metal contributing to the computed indices is Hg. There are regional differences in the content of heavy metals, especially Hg. The box plot analysis suggest that the wheat irrigation water in Qinglong town,Jiudian town and Dulou town is contaminated by anthropogenic such as mineral activity. The pollution status of wheat irrigation systems in the study area are of great environmental and health concerns.