Probabilistic risk assessment and source identification of heavy metals in soil-rice systems in northern area of Fujian Province, China

In this study, the ecological-human health risks and sources of heavy metals in paddy soils in the northern area of Fujian Province were investigated. The innovative ecological and health indicators that were evaluated in a probabilistic form were utilized rather than the traditional quotient form to make the results more accurate. By considering the bioaccessibility (BA) of heavy metals when calculating the hazard index (HI) for non-carcinogenic risks and total carcinogenic risk (TCR) for carcinogenic risk, the health risks caused by the ingestion of rice grains were significant. The HI and TCR values for both children and adults exceeded the standard values. In the meantime, the health risks of heavy metals in soils were not as high as expected. The geochemical baseline value (GBV) of Cd (0.087 mg/kg) was higher than the background concentration value (BCV) (0.054 mg/kg). The species sensitivity distribution (SSD) curves were built to determine the threshold values (hazardous concentration, HC_p) of soil heavy metals that can protect 5 %, 50 %, and 95 % of local rice varieties. The results showed that the allocation of rice production areas in the study site appeared to be largely in accordance with the needs of rice production. The outcomes of the APCA-MLR model indicated that the main sources included mining and associated industrial activities, natural sources, and agricultural activities, with a total contribution rate of 37.4 %, 30 %, and 32.6 % to the accumulation of heavy metals, respectively. The findings of this study contribute to the deeper understanding of the impact of heavy metal pollution in paddy soils on the health of local people and agroecosystems.