Objective To analyze soil pollution characteristics of heavy metals in different urban functional areas of Baoji City, Shaanxi Province, and evaluate their potential health risks.
Methods A total of 109 surface soil samples were collected from residential, traffic, industrial, and commercial areas of Baoji. Inductively coupled plasma-mass spectrometry was used to detect five heavy metals in the samples, including Cr, Cd, Ni, Cu, and Zn. Nemerow comprehensive pollution index PN and health risk assessment model were applied to evaluate the pollution levels and human health risks of heavy metals.
Results The average contents of Cr, Cd, Ni, Cu, and Zn in selected functional areas exceeded the corresponding background values of Shaanxi Province, which indicated different degrees of pollution, and Cd pollution was the most serious. The results of Nemerow comprehensive index PN showed that the heavy metal pollution levels of the selected functional areas were industrial district (8.2) > traffic area (6.9) > commercial area (6.7) > residential area (6.3), and all were seriously contaminated. The results of health risk assessment model showed that the total carcinogenic risks of Cr and Ni from higher to low were residential area > traffic area > commercial area > industrial area, while the risk of Cd was residential area > industrial area > traffic area > commercial area. Cd and Ni in different functional areas had no carcinogenic risk (< 1×10-6), and the carcinogenic risk of Cr was within acceptable level (1×10-6-1×10-4). The non-carcinogenic hazard index of Cr in residential area was 2.62, and the indices in the other functional areas were all < 1.
Conclusion Severe contamination of heavy metals in soil is identified in the studied area. Cd is the main heavy metal with both carcinogenic risk and non-carcinogenic risk, requiring attention its potential risks.
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