Agricultural impacts reshape the distribution and future potential health risks of soil heavy metals across global wheat-growing regions under interactive climate-socioeconomic influences.

Abstract

Soil heavy metal(loid) pollution poses a critical threat to ecosystem health and sustainability. However, it remains unclear whether agricultural activities have systematically altered their distribution across global wheat-growing regions. Here, we collected paired soil samples from cropland and adjacent non-cropland sites across global wheat-growing regions on six continents to evaluate concentration differences and potential drivers for six heavy metal(loid)s-arsenic (As), nickel (Ni), cadmium (Cd), lead (Pb), antimony (Sb), and chromium (Cr). We found clear element-specific patterns: Ni was enriched in high-input agricultural regions, whereas Pb and Cr were more concentrated in non-croplands. These differences varied by region. Using extreme gradient boosting (XGBoost) and Shapley additive explanations (SHAP), we identified fertilization intensity, moisture conditions, and socioeconomic development as key nonlinear predictors. Projections under the SSP2-4.5 and SSP5-8.5 scenarios suggest that by 2100, these concentration differences may either reverse or intensify, with their spatial evolution accompanied by shifts in potential non-carcinogenic health across cropland soils. Our findings show that agricultural land use is closely associated with spatial patterns of soil heavy metals across global wheat-growing regions and highlight land-use differentials as valuable early indicators of pollution risk, particularly in major wheat-producing regions.