Persistent arsenate-iron(iii) oxyhydroxide-organic matter nanoaggregates observed in coal

Zhang，Yinfeng1,2; Li，Shehong2; Sun，Jing2; Bostick，Benjamin C.3; Zheng，Yan4,5

2021-10-01

10.1039/d1en00502b

Environmental Science-Nano   影响因子和分区

2051-8153

2051-8161

Understanding how natural nanoaggregates of iron (Fe) and organic matter (OM), currently identified in organic rich soil or peat, interact with metals and metalloids is environmentally significant. Coal is also organic-rich and exemplifies anoxic sedimentary environments with Fe usually as pyrite and not oxides. Here, we analyze the local structure of Fe (6880-21 700 mg kg-1) and As (45-5680 mg kg-1) in representative Guizhou coal samples using X-ray absorption near-edge structure and extended X-ray absorption fine structure (XANES and EXAFS) to illustrate how Fe(iii) and As(v) are preserved in coal formed from reduced, organic-rich precursors. Arsenic XANES indicates that >80% of As exists as As(v) with <14% of As associated with sulfides in 5 Guizhou coal samples, confirming published but unexplained results. An As-Fe shell at 3.25-3.29 Å in the As EXAFS suggests that this As(v) is adsorbed on Fe(iii) oxyhydroxides as evidenced by Fe EXAFS in these coal samples. Significantly, lower Fe-Fe coordination numbers (CN) of 0.6-1.1 relative to those in 2-line ferrihydrite (CN = 1.6) and goethite (CN = 2.1) suggest that these Fe(iii) oxyhydroxides are likely Fe-OM nanoaggregates protected by OM encapsulation and adsorption of arsenate. Such structurally stabilized composites of As(v)-Fe(iii)-OM may be more widely distributed and allow oxidized As and Fe to persist in other organic-rich, reducing environments.

SCI ; EI

英语

通讯

WOS:000691770400001

20214311057366

Absorption spectra ; Biogeochemistry ; Extended X ray absorption fine structure spectroscopy ; Organic compounds ; Pyrites ; Sulfur compounds ; X ray absorption ; X ray absorption near edge structure spectroscopy

Geochemistry:481.2 ; Solid Fuels:524 ; Electromagnetic Waves:711 ; Electromagnetic Waves in Relation to Various Structures:711.2 ; Biochemistry:801.2 ; Organic Compounds:804.1 ; Atomic and Molecular Physics:931.3

2-s2.0-85117482219

Scopus

1.Yunnan Key Laboratory of Plateau Wetland Conservation,Restoration and Ecological Services,College of Wetlands,Southwest Forestry University,Kunming,650224,China
2.State Key Lab of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang,550081,China
3.Lamont-Doherty Earth Observatory,Columbia University,Palisades,61 Route 9W,10964,United States
4.State Environ. Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control,School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
5.Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control,School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China

Zhang，Yinfeng,Li，Shehong,Sun，Jing,et al. Persistent arsenate-iron(iii) oxyhydroxide-organic matter nanoaggregates observed in coal[J]. Environmental Science-Nano,2021,8(10):2964-2975.

Zhang，Yinfeng,Li，Shehong,Sun，Jing,Bostick，Benjamin C.,&Zheng，Yan.(2021).Persistent arsenate-iron(iii) oxyhydroxide-organic matter nanoaggregates observed in coal.Environmental Science-Nano,8(10),2964-2975.

Zhang，Yinfeng,et al."Persistent arsenate-iron(iii) oxyhydroxide-organic matter nanoaggregates observed in coal".Environmental Science-Nano 8.10(2021):2964-2975.