Quantifying metal transferability in soil and its relationship to metal-related health risks in the strawberry (Fragaria × ananassa)-human food chain

Abstract

Understanding metal transfer in soil-strawberry systems is indispensable for sustainable strawberry production. To date, much attention has been paid to metals in strawberries, while metal transferability in strawberry-growing soil has been ignored. In this study, the availability, mobility, and bioavailability indices established based on BCR-extracted metal fractions and previously used for metal bioavailability evaluation in sediments were utilized to estimate metal transferability in soil sampled from strawberry orchards in the Yangtze River Delta, China, and predict metal-related health risks in strawberries. Overall, soil Pb, Cr, Ni, and Cu had their average bioavailability index (BI) values lower than 0.1, indicating low bioavailability of these metals. In contrast, soil Cd and Zn generally exhibited very high and moderate bioavailability, as their mean BI values reached 1.46 and 0.241, respectively. Furthermore, the mean values of total mobility and availability indices were 0.427 and 0.566, respectively, suggesting high mobility and availability for soil metals. Notably, the significant increase of soil Cr bioavailability induced by the acidification of strawberry-growing soil exacerbated the cancer risk caused by gastrointestinal bioaccessible Cr in strawberries. Overall, these indices, particularly the bioavailability index, can effectively reflect soil metal bioavailability and predict metal-related health risks in strawberries.