The coupling of sulfide and Fe-Mn mineral promotes the migration of lead and zinc in the redox cycle of high pH floodplain soils

Qianqian Yu; Junwei Wen; Sili Zhang; Chen Wu; Hao Ouyang; Nannan Hu; Xu Li; Xinhong Qiu

doi:10.1016/j.jhazmat.2024.134546

The coupling of sulfide and Fe-Mn mineral promotes the migration of lead and zinc in the redox cycle of high pH floodplain soils

J Hazard Mater. 2024 May 5:472:134546. doi: 10.1016/j.jhazmat.2024.134546. Online ahead of print.

Authors

Qianqian Yu¹, Junwei Wen², Sili Zhang², Chen Wu², Hao Ouyang², Nannan Hu², Xu Li², Xinhong Qiu³

Affiliations

¹ State Key Laboratory of Biogeology and Environmental Geology, Hubei Key Laboratory of Critical Zone Evolution, School of Earth Science, China University of Geosciences, Wuhan 430074, China. Electronic address: yuqq@cug.edu.cn.
² State Key Laboratory of Biogeology and Environmental Geology, Hubei Key Laboratory of Critical Zone Evolution, School of Earth Science, China University of Geosciences, Wuhan 430074, China.
³ School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430205, China. Electronic address: qxinhong@gmail.com.

PMID: 38735185
DOI: 10.1016/j.jhazmat.2024.134546

Abstract

In this study, we investigated the impact of fluctuating water levels on the distribution of lead (Pb) and zinc (Zn) in soil and sediments at a historical Pb-Zn smelting site along the Xiangjiang River. Despite the high pH levels (7 to 11) in the study area, which generally inhibits heavy metal solubility, we found that regular changes in water levels still affect Pb-Zn movement. Soil analysis revealed distinct redox zones within the unconfined aquifer, as shown by the variable Fe/Mn and Ce/Ce* ratios. Advanced techniques such as Mn K-edge XAFS, Mössbauer spectroscopy, and TOF-SIMS indicated persistent Fe-Mn redox cycling and highlighted the presence of Pb and Zn-rich manganese oxides near sulfur-bearing minerals. These findings suggest that acidic microzones produced by the oxidation of sulfur-bearing minerals become "refuges" for microbial and heavy metal activity. Considering that sulfur-containing minerals are widespread waste types in nonferrous metal smelting sites, these findings are instructive for a better understanding of the transformation mechanisms of heavy metal ions in nonferrous metal smelting-polluted environments and for guiding pollution remediation strategies.

Keywords: Fe-Mn redox cycle; Heavy metal pollution; High-pH soils; Nonferrous smelting sites; Water level fluctuation.