Comprehensive Source Apportionment and Health Risk Assessment of Metals Contamination with Unified Approach of Receptor Model and Monte Carlo Simulation in Limpopo, South Africa

Abstract

The contamination of soil and water poses a serious threat to humans and the surrounding ecosystems globally. A detailed source apportionment was done using EPA Positive Matrix Factorization (PMF) model in Luvuvhu and Mutale river catchment in Limpopo province. Groundwater contamination was found to be mainly caused by agricultural leaching, basaltic weathering, geothermal, domestic, mining and municipal sewage. Geothermal sources in soil are responsible for 42% of non-carcinogenic risk (NCR) especially from Co, whereas basaltic soil accumulation contributed 76% of the risk in carcinogenic (CR) scenario. Similarly, leaching Co and Cr from mining activities was found responsible for 68% and 42% of non-carcinogenic and carcinogenic risk in groundwater for both adult and children. Source oriented health risk simulation using Monte Carlo simulation highlighted a risk of non-carcinogenic metals 55% of the simulated cases whereas carcinogenic metals pose high risk in 90% of the scenarios for children in soil. On the other hand, NCR for groundwater was found to be negligible in the study area, whereas higher variability in concentration of Cd and Cr in groundwater showed high carcinogenic risk for both adults and children in 100% of the simulated scenarios. Similarly, source oriented pollution and ecological risk assessment using Single-factor pollution load index (SPLI zone ) and Single-factor ecological load index (SELI zone ) revealed higher ecological risk from basaltic soil accumulation due to higher presence of Ni aided with higher toxicity of Cd and Pb. The study provides scientific support for the prevention of human and ecological damage along with control of pollution in soil and groundwater.

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