Simulated scenario models to assess the long-term effects of Cr(VI)-contaminated soils remediated with typical iron-bearing reductants

• Published in: Journal of soils and sediments Vol. 24; no. 5; pp. 1988 - 2000
• Main Authors: Zhang, Xiaoming, He, Yuhong, Li, Qi, Liao, Qi, Si, Mengying, Yang, Zhihui, Yang, Weichun
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2024; Springer Nature B.V
• Subjects: Acid rain; Chemical reduction; Chromium; Earth and Environmental Science; Environment; Environmental Physics; Ferrous sulfate; Freeze thaw cycles; Freeze-thawing; Iron; Iron sulfates; Iron sulfides; Leaching; Long-term effects; Materials selection; Microorganisms; Oxidation; Oxidation resistance; Pyrite; Reducing agents; Sec 3 • Remediation and Management of Contaminated or Degraded Lands • Research Article; Soil; Soil contamination; Soil microorganisms; Soil pollution; Soil remediation; Soil Science & Conservation; Soil treatment; Soils; Stability; Acid rain leaching; Alternating wet-dry; Cr redox interconversion; Freeze–thaw cycles; Cr(VI) reduction; Manganese oxide
• ISSN: 1439-0108; 1614-7480
• DOI: 10.1007/s11368-024-03761-6

Purpose The chemical reduction of Cr(VI)-contaminated soil can be subject to re-oxidation when the external environment changes, and it is therefore crucial to assess the long-term stability of the remediated soil. Materials and methods In this work, we systematically investigated the remediation performance of nano-zerovalent iron (nZVI), ferrous sulfate (FeSO 4 ), and zerovalent iron/pyrite (ZVI/FeS 2 ) in Cr(VI)-contaminated soil, with particular emphasis on assessing the long-term stability of Cr(VI)-contaminated soil after their remediation by adopting various simulated scenarios models, including freeze–thaw cycles (FTC) aging, acid rain (AR) leaching, alternating wet-dry (AWD), and extreme oxidation. Results and discussion The results showed that compared to nZVI and FeSO 4 , ZVI/FeS 2 exhibited superior Cr(VI) reduction performance with a reduction efficiency of 99.8% and improved the richness and diversity of soil microbial community. The stability of Cr in soils remediated with ZVI/FeS 2 and FeSO 4 was not significantly affected by FTC, AR leaching, and AWD, with almost no changes in Cr(VI) content in the two soils under any circumstance, except for a slight increase in Cr(VI) concentration in FeSO 4 treated one under AWD condition. By contrast, the addition of exogenous Mn oxides led to an increase in total Cr(VI) concentration of 167.98, 136.35, and 50.35 mg kg −1 in the control, FeSO 4 , and ZVI/FeS 2 -treated soil, respectively. The ZVI/FeS 2 treated one exhibited preferable resistance to Cr(VI) re-oxidation. Conclusions Our findings illustrated that soil oxidation condition is an important factor affecting the long-term stability of remediated Cr(VI)-contaminated soil and provided critical information on guidance of selecting reducing materials for Cr(VI)-contaminated soil remediation.