Human activity and soil N impact spatial distribution patterns of soil heavy metal pollution in China

Soil heavy metal pollution has emerged as a critical environmental challenge in China. Despite growing concerns, the spatial distribution patterns and land-use pollution characteristics remain poorly characterized. This nationwide investigation analyzed 7 priority heavy metals (cadmium (Cd), arsenic (As), lead (Pb), zinc (Zn), copper (Cu), chromium (Cr) and nickel (Ni)) across 33 study sites, employing structural equation modeling and random forest analysis to quantify drivers for heavy metal pollution pattern. Our results showed that the spatial distribution pattern of heavy metal pollution in China was negatively correlated with latitude. Cd, As, Pb and Zn should be the priority heavy metals to be controlled, with Cd exceeding the national standard by as much as 27.3 %. In addition, compared with other land, industrial and mining storage land pollution is the most serious, should be given priority control. The structural equation model showed that human, soil and climate together explain 39 % of the variance of heavy metal pollution. Random forest analysis suggested that human activity and N had the greatest relative influence on heavy metal pollution evaluation indexes. These findings provide a scientific basis for developing targeted remediation strategies and implementing differentiated land use management programs.