Risk Assessment of Heavy Metal Distribution in Soil of a Typical Tourist Island in South China

Abstract

The concentrations of seven heavy metals (Hg, Cd, Pb, Cu, As, Cr and Zn) were measured in 20 topsoil samples collected from Sanjiaozhou Island to (1) reveal the distribution of heavy metals in soils after long-term human activities on an uninhabited island, and ( 2) analyze the ecological risks associated with soil heavy metals. According to the measured heavy metal concentrations, Zn (88.07 mg/kg) had the highest concentration, which was followed by Pb, Cr, Cu, As, Hg and Cd. Additionally, the average concentrations of Pb (73.86 mg/kg) and Hg (0.17 mg/kg) exceeded the background values 1.23 and 1.31 times, respectively. The analyzed contamination degrees, based on the contamination factor index (P i ) and geoaccumulation index (I geo ) values, were mostly low, but were high for Hg and Pb. The mean value of the potential ecological index (RI) of heavy metals in soils was 80.95, indicating a relatively low potential ecological risk. In terms of the individual metal ecological index (E i ) value, Hg was the highest followed by Cd, Pb, Cu, As, Cr and Zn. Hg resulted in a higher ecological risk, as its average E i was 52.31, suggesting a moderate risk to the environment. Based on the distribution of the metals, domestic sewage discharge and agricultural inputs are most likely to be the primary sources of metal pollution on the island.