Heavy metals in river surface sediments affected with multiple pollution sources, South China: Distribution, enrichment and source apportionment

Understanding sources and fate of heavy metals in river basin is crucial for assessing risks associated with human and ecosystem exposure. To provide basic information for agriculture and industry transferring in future, environmental development planning and decision-making, and drinking water source protecting associated with human health in the region, compound heavy metal pollution in the Maba River, South China, was investigated to evaluate spatial distribution and pollution levels using geo-accumulation index (Igeo). In addition, heavy metal concentrations in sediments were measured and compared with sediment quality guidelines (SQGs). The main contamination sources of heavy metals and the concrete contribution were identified and calculated using multivariate statistical analysis (MSA) and factor analysis-multiple linear regression (FA-MLR) methods. The results showed that the heavy metals exposed in sediments of the Maba River largely due to anthropogenic sources, such as smelting and mining. The heavy metal concentrations found in surface sediments were significantly higher than the local background values, especially in the mixed region. The migration and transformation process of river metals was mainly affected by hydraulic conditions and sediment characteristics. The Igeo and SQGs produced similar levels of heavy metals pollution in sediments, thereby confirming each other's results, indicating that the Maba River is heavily contaminated, and As, Hg, Pb, Zn, Cd and Cu were likely to effect on the aquatic ecosystem. Based on MSA and FA-MLR, the results showed that about 87% of Cu came from the mine tailing wastewater runoff, 77%, 66% and 72% of Tl, Hg and Cd respectively originated from the smelting wastewater discharge. Results of this study will be useful in assessing and managing regional point source pollution. Further investigation on fate and toxicity of heavy metals associated with human health risks is needed in future studies.