Page 87 - 2017地大报告电子书

环境学院发展报告

摘 要：The Xikuangshan(XKS) mine, the world’s largest antimony mine, was chosen for

a detailed arsenic hydrogeochemical study because of the elevated arsenic in bedrock aquifers used
by local residents. Hydrochemical data, δ34S values of dissolved SO42 − and 87Sr/86Sr ratios

have been analyzed to identify the predominant geochemical processes that control the arsenic
mobilization within the aquifers. Groundwater samples can be divided into three major types: low

arsenic groundwater (0–50 µg/L), high arsenic groundwater (50–1000 µg/L) and anomalous
high arsenic groundwater (>1000 µg/L). Arsenic occurs under oxidizing conditions at the XKS

Sb mine as the HAsO42 − anion. The Ca/Na ratio correlates significantly with HCO3 − /Na
and Sr/Na ratios, indicating that carbonate dissolution and silicate weathering are the dominant

processes controlling groundwater hydrochemistry. The δ34S values of the groundwater indicate
that dissolved SO42 − in groundwater is mainly sourced from the oxidation of sulfide minerals,

and elevated As concentrations in groundwater are influenced by the mixing of mine water and
surface water. Furthermore, the δ34S values are not correlated with dissolved As concentrations

and Fe concentrations, suggesting that the reduction dissolution of Fe(III) hydroxides is not
the dominant process controlling As mobilization. The 87Sr/86Sr ratios imply that elevated

As concentrations in groundwater are primarily derived from the interaction with the stibnite
and silicified limestone. More specifically, the excess-Na ion, the feature of Ca/Na ratio,

and the spatial association of elevated As concentrations in groundwater collectively suggest
that high and anomalous high arsenic groundwater are associated with smelting slags and, in

particular, the arsenic alkali residue. In general, the hydrochemistry analysis, especially the S
and Sr isotope evidences elucidate

that elevated As concentrations
and As mobilization are influenced

by several geochemical processes,
including: (1) bedrock weathering;

(2) oxidation of arsenopyrite and the
dominant sulfides in the ores; (3) mixing

of mine drainage and surface water; (4) leaching of the arsenic alkali residue; and (5) sorption-
desorption from Fe/Mn oxides/hydroxides.

论文链接：https://doi.org/10.1016/j.jhydrol.2017.12.013

19.Evaluation of Mercury Stabilization Mechanisms by Sulfurized Biochars Determined
using X-ray Absorption Spectroscopy

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