Recognition method for the health risks of potentially toxic elements in a headwater catchment

The spatial association of potentially toxic elements (PTEs) in soil-crop-groundwater systems is poorly recognised. In this study, the contents of arsenic (As), cadmium (Cd), copper (Cu) and lead (Pb) in paddy soils, rice and groundwater in the Xiancha River catchment were determined. The intrinsic effects of PTEs in soils on their spatial distribution in groundwater and rice were explored. Also, the potential sources and health risks of PTEs in multi-media were investigated. Results showed that the mean contents of As and Cd in soils were 23.86 and 0.26 mg kg(-1), respectively. In groundwater, the maximum (average) content of As reached 6.55 (1.84) mu g L-1. Moreover, As contents in soils and groundwater showed a sound spatial correlation (q = 0.81), and this is supported by the result of the soil column experiment, indicating homology and the strong vertical migration capacity of As. The non-homologous patterns of Pb, Cu and Cd contaminations in soil-groundwater system suggested that geogenic processes influenced the distribution of these PTEs. Cd presented a poor spatial correlation in soil-rice system, as multiple factors controlled its transfer process. Multivariate statistical analysis results demonstrated that As, Cu and Pb in soils mainly came from agricultural sources, whereas high Cd levels were from mining activities. Additionally, direct consumption of As-contaminated groundwater and Cd-contaminated rice posed significant health risks to local residents. This study, which proposes a risk recognition method used to investigate target PTEs in multi-media, may serve as a valuable reference for further research involving catchments.

Automated summary

This study focuses on the spatial association and distribution of potentially toxic elements (PTEs) in soil-crop-groundwater systems. Results show that there is a strong spatial correlation between the contents of arsenic (As) in paddy soils and groundwater. The distribution of lead (Pb), copper (Cu), and cadmium (Cd) in the soil-groundwater system is influenced by geogenic processes. Agricultural sources contribute mainly to As, Cu, and Pb in soils, while mining activities contribute to high Cd levels. Consumption of As-contaminated groundwater and Cd-contaminated rice pose significant health risks to local residents.