To ensure farmland soil quality and enable the systematic management of heavy metal contamination, this study assessed cadmium (Cd), mercury (Hg), and arsenic (As) levels in 114 surface soils from farmlands across four cities in Heilongjiang Province, China. The heavy metal elements were determined and comprehensively evaluated using four indices (geo-accumulation index, single factor contamination index, Nemerow index, and potential ecological risk index). Monitoring results showed that most soil samples exhibited concentrations of Cd, Hg and As that were below the risk screening values specified in relevant standards, except for those with slightly higher Cd concentration in a few soil samples from Suihua City. Comprehensive evaluation indicated a slightly to moderately Cd contamination across the study area, with Suihua City demonstrating the most prominent pollution levels. Factors such as railway traffic emissions might have caused Cd contamination in the surrounding farmland soil. Health risk assessments confirmed that the study area posed no significant carcinogenic or non-carcinogenic risks to children or adults via soil exposure. These findings highlight the need for priority monitoring of heavy metal concentrations and implementation of targeted soil protection measures to ensure both human health and sustainable agricultural development. It is necessary to closely monitor various potential pollution sources during the operation of surrounding railway lines, which is to prevent the formation of Cd-contaminated areas due to the long-term effects of railway transportation. The results of this study will have certain significance for the evaluation and management of regional farmland land pollution.
Hao et al. (2026) studied this question.