Effects of adsorbed phosphate on jarosite reduction by a sulfate reducing bacterium and associated mineralogical transformation

Kun Gao; Yue Hu; Chuling Guo; Changdong Ke; Chucheng He; Xinrui Hao; Guining Lu; Zhi Dang

doi:10.1016/j.ecoenv.2020.110921

Effects of adsorbed phosphate on jarosite reduction by a sulfate reducing bacterium and associated mineralogical transformation

Ecotoxicol Environ Saf. 2020 Oct 1:202:110921. doi: 10.1016/j.ecoenv.2020.110921. Epub 2020 Jun 29.

Authors

Kun Gao¹, Yue Hu¹, Chuling Guo², Changdong Ke¹, Chucheng He¹, Xinrui Hao¹, Guining Lu¹, Zhi Dang³

Affiliations

¹ School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, PR China.
² School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, PR China. Electronic address: clguo@scut.edu.cn.
³ School of Environment and Energy, South China University of Technology, Guangzhou, 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, PR China. Electronic address: chzdang@scut.edu.cn.

PMID: 32800256
DOI: 10.1016/j.ecoenv.2020.110921

Abstract

Jarosite is one of the iron oxyhydroxysulfate minerals that are commonly found in acid mine drainage (AMD) systems. In natural environments, phosphate and sulfate reducing bacteria (SRB) may be coupled to jarosite reduction and transformation. In this research, the effect of phosphate on jarosite reduction by SRB and the associated secondary mineral formation was studied using batch experiments. The results indicated that Fe³⁺ is mainly reduced by biogenic S^2- in this experiment. The effect of PO₄^3- on jarosite reduction by SRB involved not only a physico-chemical factor but also a microbial factor. Phosphate is an essential nutrient, which can support the activity of SRB. In the low PO₄^3- treatment, the production of total Fe²⁺ was found to be slightly larger than that in the zero PO₄^3- treatment. Sorption of PO₄^3- effectively elevated jarosite stability via the formation of inner sphere complexes, which, therefore, inhibited the reductive dissolution of jarosite. At the end of the experiment, the amounts of total Fe²⁺ accumulation were determined to be 4.54 ± 0.17^a mM, 4.66 ± 0.22^a mM, 3.91 ± 0.04^b mM and 2.51 ± 0.10^c mM (p < 0.05) in the zero, low, medium and high PO₄^3- treatments, respectively, following the order of low PO₄^3- treatment > zero PO₄^3- treatment > medium PO₄^3- treatment > high PO₄^3- treatment. PO₄^3- loading modified the transformation pathways for the jarosite mineral, as well. In the zero PO₄^3- treatment, the jarosite diffraction lines disappeared, and mackinawite dominated at the end of the experiment. Compared to PO₄^3--free conditions, vivianite was found to become increasingly important at higher PO₄^3- loading conditions. These findings indicate that PO₄^3- loading can influence the broader biogeochemical functioning of AMD systems by impacting the reactivity and mineralization of jarosite mineral.

Keywords: Jarosite; Mackinawite; Phosphate; Sulfate reducing bacteria; Vivianite.

MeSH terms

Adsorption
Bacteria / metabolism*
Biodegradation, Environmental
Ferric Compounds / chemistry*
Ferrous Compounds
Iron / chemistry
Iron Compounds / chemistry
Minerals
Mining
Oxidation-Reduction
Phosphates / chemistry*
Sulfates / chemistry*

Substances

Ferric Compounds
Ferrous Compounds
Iron Compounds
Minerals
Phosphates
Sulfates
jarosite
ferrous phosphate
Iron
ferrous sulfide