Spatial delineation of AMD sources in a pyrite-rich waste rock site with spectral induced polarization method

Sheng Zhou; Yi-Xin Yang; Long-Long Meng; Ai-Fang Du; Qiong Wang; Chi Zhang; Shuai Zhang; Bate Bate

doi:10.1016/j.jhazmat.2025.138919

Spatial delineation of AMD sources in a pyrite-rich waste rock site with spectral induced polarization method

J Hazard Mater. 2025 Jun 14:495:138919. doi: 10.1016/j.jhazmat.2025.138919. Online ahead of print.

Authors

Sheng Zhou¹, Yi-Xin Yang¹, Long-Long Meng¹, Ai-Fang Du², Qiong Wang², Chi Zhang³, Shuai Zhang¹, Bate Bate⁴

Affiliations

¹ Institute of Geotechnical Engineering, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China; MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310058, China.
² BGRIMM Technology Group, Beijing 100160, China.
³ Department of Meteorology and Geophysics, University of Vienna, Vienna 1010, Austria.
⁴ Institute of Geotechnical Engineering, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, China; MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310058, China. Electronic address: batebate@zju.edu.cn.

PMID: 40543344
DOI: 10.1016/j.jhazmat.2025.138919

Abstract

Pyrite within waste rock piles generates acid mine drainage upon precipitation, posing a significant environmental risk. In this study, spectral induced polarization (SIP) technique was employed at the field scale to delineate the contaminant source in a 25 m-long waste rock pile site (117.76°E, 28.99°N) with decimeter-level resolution. Laboratory SIP tests and microscopic analyses were performed to elucidate the dynamic geochemical mechanisms. Pyrite was identified as the primary acid-generating source and polarizable unit within the waste rock pile in this study. Complex conductivity profiles delineated an active pyrite oxidation hotspot, a preferential flow path and a layer of vadose region. Based on the mapped typical locations, the life cycle of pyrite in a waste rock site was revealed as follows: pyrite oxidation, Fe³⁺dissolution and migration, and reprecipitation in the form of jarosite, which is coated on pyrite and forms a passivation layer. With jarosite precipitation, the average diameter of pyrite-jarosite grains increased from 0.5 to 1 μm via SEM observation, which agreed with the peak frequency reduction from 3000 to 200 Hz. This study demonstrated the feasibility of SIP technology for contamination source detection, remediation guidance and risk assessment of waste rock sites.

Keywords: Acid mine drainage; Monitoring; Pyrite; Spectral induced polarization; Waste rock.