Sixteen-year dynamics of heavy metal(loid) pollution in agricultural soils of Zhejiang Province, China: Quantifying the contest between anthropogenic pressures and environmental investments.

Soil contamination by heavy metal(loid)s represents a persistent environmental challenge in rapidly industrializing regions, yet long-term studies tracking pollution trajectories remain scarce. This study presents a 16-year (2007-2023) investigation of eight heavy metal(loid)s in agricultural soils across Zhejiang Province, China, integrating spatial analysis, positive matrix factorization (PMF), and socioeconomic correlation analysis. Results reveal divergent regional-scale directional changes in which cadmium concentrations, after a significant mid-period increase, declined to levels statistically indistinguishable from the 2007 baseline by 2023, representing a regional-scale directional reversal, while chromium and nickel stabilized following initial accumulation. Spatial analysis demonstrated a westward migration of pollution hotspots, with the center of ecological risk gravity shifting from southeastern to northwestern Zhejiang. PMF identified five sources-geological background, agricultural practices, industrial processes, coal combustion, and traffic emissions-with agricultural contributions to zinc and copper increasing to 38% and 20%, respectively, by 2023. Environmental protection governance investment (EPGI) was negatively associated with soil metal(loid) concentrations, with the strongest association at a 2-3 year lag (r = -0.32 to -0.64, p < 0.05), consistent with a mitigating role of sustained investment. The integrated application of hotspot detection with dynamic source apportionment demonstrates a practical strategy for evidence-based soil management. The observed EPGI-metal(loid) associations, derived from repeated cross-sectional surveys, should be interpreted as regional-scale directional changes rather than tracked within-site trajectories. This study documents one of the few provincial-scale cases of a regional-scale directional reversal of cadmium contamination in a rapidly industrializing region and offers a replicable framework for evidence-based soil environmental management.