Determination, Source Identification and Risk Assessment of Heavy Metal Pollution in Agricultural Soil Near a Typical Industrial Zone in Northern Ningxia, China

Agricultural soil pollution affects agricultural productivity and human health. To assess the degree and potential risk of heavy metals (HMs) pollution in agricultural soil in typical industrial areas in northern Ningxia, China, the levels of 8 HMs including Hg, As, Cu, Zn, Ni, Cd, Pb, and Cr were detected, the associated ecological and health risks were assessed, and the sources were identified. The results showed that, compared with the corresponding standards, the Hg, Zn, and As exceeded the standards by 27, 18, and 4%, respectively. Pollution Index, Hakanson's potential risk index and enrichment factor showed that the Hg pollution was most serious. The spatial distribution results showed the HMs were associated with mining sites, industrial parks or cities. Positive matrix factorization (PMF) results showed the HMs in soil can be attributed to 4 factors, its contribution order is industrial activity (53.1%) > traffic (18.3%) > natural (17.0%) > mining activity (9.8%). The health risk analysis showed a non-carcinogenic risk at 0.136 (<1) and carcinogenic risk was 126 x 10(-5) (<10(-4)), indicating a low risk of residents. However, consumption of crops food grown in the area is the most important approach resulting in health risk. In summary, HMs posed a high ecological risk which mainly due to industrial activity, however, the potential health risk was acceptable. This study is very meaningful to prevent soil from HMs pollution and guarantee the agricultural soil and crop qualities.