Topography-driven variability in atmospheric deposition and soil distribution of cadmium, lead and zinc in a mountainous agricultural area.

Topography can significantly influence the atmospheric deposition of heavy metals on the surface soil and further shape their spatial distribution. This study was carried out in Northwestern Guizhou Province, a key agricultural region contaminated with cadmium (Cd), lead (Pb), and zinc (Zn) in agricultural soil. In this study, geographical detectors were employed to quantitatively assess the impact of topography on the spatial distribution of Cd, Pb, and Zn in surface soils. Moreover, the influence of topography on the spatial distribution of Cd, Pb, and Zn in the surface soil was further ascertained using geographical detectors. The results demonstrated that the bulk atmospheric deposition fluxes of Cd in Dawan (DW), Dongfeng (DF), Jinzhong (JZ), Shuanglong (SL), and Heishitou (HST) were 1.538, 0.766, 0.802, 0.365, and 0.186 mg m a, respectively; For Pb, the corresponding values were 47.13, 34.88, 38.25, 16.95 and 35.76 mg m a, respectively; in the case of Zn, the fluxes were 579.26, 82.38, 83.20, 45.98, and 29.13 mg m a, respectively. The atmospheric deposition fluxes of Cd, Pb, and Zn demonstrated a general downward trend from DW to SL because of rainfall reduction with increasing elevation. Industrial activities can significantly increase atmospheric deposition fluxes of Cd, Pb, and Zn. However, the atmospheric deposition fluxes of Cd, Pb, and Zn in the control area HST were significantly lower due to the interception effect of mountain. The results of the Pb isotopic analysis further supported the above conclusions. It also indicated that the atmospheric Pb in DW, DF, JZ, and SL were contaminated by multiple anthropogenic sources, whereas the atmospheric Pb in HST was primarily polluted by burning coal from residents. The geographical detector analysis results demonstrated that the spatial distribution of Cd, Pb, and Zn in the surface soil at JZ was affected by the interaction of topography with organic matter and particle size. In SL, the influence of the interactions of all topographies with physical and chemical characters on the spatial distribution of soil Cd and Pb was significant. The aspect was the only topographical factor influencing Zn. Furthermore, topography and pH were the leading factors affecting the spatial distribution of soil Cd, Pb, and Zn in HST. Therefore, this research provides a scientific basis for the identification of pollution sources and the development of effective soil heavy metal control strategies.