Objective Groundwater containing arsenic (As) is widely used for irrigation worldwide, yet there is limited research on how arsenic in groundwater affects the total concentration, speciation, and bioavailability of arsenic in irrigated soils, as well as its accumulation in vegetables. Such studies are crucial for ensuring agricultural safety and assessing human health risks.
Method Two batches of soil and vegetable samples were collected from farmland irrigated using geogenic arsenic-contaminated groundwater. Arsenic and iron concentrations were analyzed and plant-available arsenic was assessed with DTPA method. Bioavailable arsenic was determined via the IVG method. Health risks were evaluated using the EPA model for three routes: direct ingestion, inhalation, and dermal contact;
Result The average arsenic concentration in soil was 26.0 ± 2.2 mg kg−1, higher than the local background value but below the agricultural soil risk threshold. The arsenic concentrations in leeks and rapeseed were within the national food safety limits. DTPA-extractable arsenic accounted for less than 0.46% and IVG-based bioavailability was below 8%. The lower bioavailability is attributed to the stronger adsorption by minerals such as iron oxides in the soils identified by sequential extraction. The bioavailability-based health risk assessment indicated that direct soil ingestion is the primary exposure route, with a non-carcinogenic risk index (HI) <1 and carcinogenic risk (CR) < 0.0001, suggesting negligible health risk from arsenic exposure;
Conclusion The arsenic levels in vegetables from the study area are safe for consumption. The arsenic bioavailability in the irrigated soil poses a negligible health risk to local populations. The findings support the safe use of groundwater for agricultural irrigation and provide a basis for the sustainable management of arsenic contaminated soil.
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