Metal distribution behavior based on soil aggregate size in a post-restoration coastal mining area

Tengfei Ma; Hanjin Luo; Jianteng Sun; Yan Pan; Kaibo Huang; Guining Lu; Zhi Dang

doi:10.1016/j.scitotenv.2022.161285

Metal distribution behavior based on soil aggregate size in a post-restoration coastal mining area

Sci Total Environ. 2023 Mar 20:865:161285. doi: 10.1016/j.scitotenv.2022.161285. Epub 2022 Dec 30.

Authors

Tengfei Ma¹, Hanjin Luo¹, Jianteng Sun², Yan Pan³, Kaibo Huang⁴, Guining Lu⁵, Zhi Dang⁶

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
² Guangdong Provincial Key Laboratory of Petrochemical Pollution Processes and Control, Guangdong University of Petrochemical Technology, Maoming 525000, China.
³ School of Environmental Engineering, Xuzhou University of Technology, Xuzhou 221000, China.
⁴ College of Ecology and Environment, Hainan University, Haikou 570228, China.
⁵ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, China. Electronic address: lutao@scut.edu.cn.
⁶ School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, China.

PMID: 36587688
DOI: 10.1016/j.scitotenv.2022.161285

Abstract

Soil aggregate size plays an important role in controlling the distribution and transport of metals. Metals immobilized in soil particles will pose potential risks through production/sink flow and infiltration. This study explored the distribution behavior of metals based on soil aggregate size in a restored coastal mining area by establishing Structural Equation Model (SEM) and column experiments. The results showed that hydrological factors and a high degree of weathering accelerated the dissolution of metals from the mine, the desorption of Wa-NH₄⁺-N, the release of F^-, and the leaching of NO₃^-. Driven by soil properties, natural factors, and anthropogenic activities, the total metal content (Total_metal) of Cr, Ni, Zn, Mn, and As showed significant spatial heterogeneity compared to Cd, Co, Cu, and Pb. The geochemical fraction of metals (Geo_metal) indicated that Cd, Co, Pb, Zn, As, and Cu are mainly present in iron‑manganese oxidation bound, organically bound, and residual fractions. The results of SEM showed that the physicochemical properties, Wa-NH₄⁺-N, nitrate nitrogen, and inorganic anions of the soil could explain 69.1 %, 76.4 %, 97.1 %, and 80.0 % of the variation in K_d-Mn, K_d-Pb, K_d-Ni, and K_d-Zn, respectively. While K_d-Cd, K_d-Cu, and K_d-Cr could be predicted by the Total_metal, but the Geo_metal seemed to have little influence on metal K_d. The results of column experiments showed that macroaggregates (>0.25 mm) significantly affected the distribution of Co, Cr, Cu, Mn, Ni, Pb, and Zn in the topsoil. The severe disruption of soil aggregate structure resulted in small fluctuations of anthropogenic Cu, Mn, Pb, Zn, and As in different layers of deep soil. In addition, mineral composition in >0.15 mm particle size was more likely to change. Overall, the hydrological cycle of coastal mines increases the uncertainty of their response to risk. Our study provides a basis for future strategies for priority control and risk prevention.

Keywords: Column experiment; Metal distribution; Soil aggregate; Structural equation model.