Mobilization of water-dispersible colloidal chromium and nickel in basalt-derived paddy soils: Role of Fe (hydr)oxides and organic matter

Ting Liu; Jingjing Li; Lirong Liu; Yanjun Jiang; Shengsheng Sun; Tenghaobo Deng; Shizhong Wang; Yetao Tang; Zhuobiao Ni; Qingqi Lin; Rongliang Qiu

doi:10.1016/j.jhazmat.2025.139188

Mobilization of water-dispersible colloidal chromium and nickel in basalt-derived paddy soils: Role of Fe (hydr)oxides and organic matter

J Hazard Mater. 2025 Jul 9:496:139188. doi: 10.1016/j.jhazmat.2025.139188. Online ahead of print.

Authors

Affiliations

¹ Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
² Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, China.
³ Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China.
⁴ Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China. Electronic address: linqingqi@scau.edu.cn.
⁵ Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510006, China.

PMID: 40652846
DOI: 10.1016/j.jhazmat.2025.139188

Abstract

Basalt weathering can lead to heavy metal enrichment in soils, and nickel (Ni) isotopes can served as an effective tracer for this weathering process. Water-dispersible colloids (WDCs) are ubiquitous in soil environments and can facilitate the long-range transport of sorbed pollutants. Here, we analyzed soil colloidal distribution, concentration, morphology and Ni isotopes in soil to understand the potential mobilization of WDC-bound Cr and Ni in basalt-derived paddy soils. Ultrafiltration results showed that on average > 90 % of Cr (4714.0 μg L^-1) and Ni (4532.3 μg L^-1) in soil solution occurring in colloid-bound form (< 1000 nm). Using AF4-UV-ICP-MS and STEM-EDS, we found that iron (Fe)-organic matter composite minerals colloids are primary carriers of Cr and Ni. Specifically, colloid-bound Cr/Ni were mainly associated with nanoparticles (1-20 nm) and fine colloid (125-350 nm) soil particle size. Notably, high weathering intensity and pH promoted the release of WDCs- Cr and Ni. Soil Ni isotopes shown light δ⁶⁰Ni composition (-0.17 ‰ ∼ -0.11 ‰), primarily determined by Ni incorporation into Fe-(hydr)oxides. Ni isotopes revealed that Ni in soil and rice originates from parent rocks. These results highlighted the pivotal role of the WDCs mobilizing heavy metals in naturally high background paddy soils.

Keywords: Chromium; Colloid; Field-flow fractionation; High geochemical background; Nickel isotope.