Accumulation Characteristics and Risk Assessment of Potentially Toxic Elements for Major Crops and Farmland Around A High-arsenic Coal Mine in Xingren, Guizhou, Southwest China

摘要

This study assessed the contamination by toxic elements (TEs), including lead (Pb), cadmium (Cd), chromium (Cr), zinc (Zn), copper (Cu) and arsenic (As), and their accumulation characteristics in soil-crop systems in Xingren, Guizhou, southwest China, by using the target hazard quotient (THQ) to evaluate the possible health risk in the target area. The mean value of the geo-accumulation index (I geo ; 1.95, 1.89 and 1.96 for rice, maize and Coix lacryma-jobi L., respectively) shows As in partial contamination level. The potential ecological risk index (RI) values show that 90% of samples exceed in considerable ecology risk level (120 < RI 240). The concentration of investigated TEs (except Zn) in the edible part of the three crops tended to be lower than in other tissues: root > stalk > leaf > husk >edible part. Maize showed a major restriction in TE intake compared to rice and Coix lacryma-jobi L. The THQ of As was from 0 to 6.33 in all the plant samples, which indicates that the THQ exceeded the safe limit (THQ=1) in some samples. The total THQs (TTHQ) had a similar trend as RI, further indicating the potential health risk of the elements in combination. These data indicate that local people experience significant health risks if they ingest crops from the investigated area.