Pollution assessment and source apportionment of heavy metal(loid)s in soil of Huangshui River basin, Qinghai Province, China

This study analyzed the contents of Cd, Co, Cr, Cu, Ni, Pb, Zn, Hg and As in 39 surface soil samples in the lower reaches of Huangshui River basin. The results showed that the proportions of Cd, Co and Cr exceeding the standard values in all samples were 17.95%, 17.95% and 12.82%, respectively. The geo-accumulation index analysis showed that 58.33% of Cd was above moderate pollution level. 64.10% of Cr was at the level of moderate pollution and above. Improved Nemerow index evaluation showed that all soil samples had ecological risk of heavy metal pollution, and 64.10% of the samples were in moderate or above pollution level. The results of potential ecological risk index showed that Cd posed a higher ecological risk than other heavy metals. There were 2.6% of the samples with high risk, and the proportions of considerable, moderate and low ecological risks were 12.8%, 2.6% and 82%, respectively. Correlation analysis and PMF analysis showed that the heavy metals in soil were mainly from atmospheric deposition, agricultural and traffic activities, industrial emissions and natural sources. The health risk of soil heavy metals is low, and the health risk caused by any exposure pathway is acceptable. In contrast, Cr, As and Pb were the most important factors contributing to non-carcinogenic risk, and As, Cd and Cr were the main carcinogenic risk factors. Children have higher health risks than adults, and the main route of exposure is ingestion.

Automated summary

This study analyzed the content of heavy metals in surface soils in the lower reaches of Huangshui River basin. The results showed that Cd, Co, and Cr exceeded the standard values in a significant proportion of samples. The analysis also revealed the sources of heavy metals and the health risk associated with them.