Reduction of iron (hydr)oxide-bound arsenate: Evidence from high depth resolution sampling of a reducing aquifer in Yinchuan Plain, China

JOURNAL OF HAZARDOUS MATERIALS

卷:406

Article

Sun, Yuqin^1,2,3  Sun, Jing⁴  Nghiem, Athena A.⁵  Bostick, Benjamin C.^2,5  Ellis, Tyler⁵  Han, Long^2,3  Li, Zengyi^2,3  Liu, Songlin^2,3  Han, Shuangbao^2,3  Zhang, Miao^2,3  Xia, Yu^2,3  Zheng, Yan^2,3 

[1] Peking Univ, Coll Engn, Beijing 100871, Peoples R China

[2] Southern Univ Sci & Technol, Sch Environm Sci & Engn, State Environm Protect Key Lab Integrated Surface, Shenzhen 518055, Peoples R China

[3] Southern Univ Sci & Technol, Sch Environm Sci & Engn, Guangdong Prov Key Lab Soil & Groundwater Pollut, Shenzhen 518055, Peoples R China

[4] Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang, Peoples R China

[5] Columbia Univ, Lamont Doherty Earth Observ, 61 Route 9W, Palisades, NY 10964 USA

关键词: Groundwater;    Arsenic;    Iron mineralogy;    X-ray absorption near edge structure (XANES);    X-ray absorption fine structure (EXAFS);   

DOI  :  10.1016/j.jhazmat.2020.124615

来源: Elsevier

【 摘 要 】

Sediment in fluvial-deltaic plains with high-As groundwater is heterogenous but its characterization of As and Fe oxidation states lacks resolution, and is rarely attempted for aqueous and solid phases simultaneously. Here, we pair high-resolution (> 1 sample/meter) Fe extended fine-structure spectroscopy (EXAFS, n = 40) and As X-ray absorption near-edge spectroscopy (XANES, n = 49) with groundwater composition and metagenomics measurements for two sediment cores and their associated wells (n = 8) from the Yinchuan Plain in northwest China. At shallower depths, nitrate and Mn/Fe reducing sediment zones are fine textured, contain 9.6 +/- 5.6 mg kg(-1) of As(V) and 2.3 +/- 2.7 mg kg(-1) of As(III) with 9.1 +/- 8.1 g kg(-1) of Fe(III) (hydr)oxides, with bacterial genera capable of As and Fe reduction identified. In four deeper 10-m sections, sulfate-reducing sediments are coarser and contain 2.6 +/- 1.3 mg kg(-1) of As(V) and 1.1 +/- 1.0 mg kg(-1) of As(III) with 3.2 +/- 2.6 g kg(-1) of Fe(III) (hydr) oxides, even though groundwater As concentrations can exceed 200 mu g/L, mostly as As(III). Super-enrichment of sediment As (42-133 mg kg(-1), n = 7) at shallower depth is due to redox trapping during past groundwater discharge. Active As and Fe reduction is supported by the contrast between the As(III)-dominated groundwater and the As(V)-dominated sediment, and by the decreasing sediment As(V) and Fe(III) (hydr)oxides concentrations with depth.

【 授权许可】

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