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Wild plant species from three deserted antimony (Sb) mine areas in southern China were collected to measure eight metal(loid)s. Antimony, As (arsenic), Cd (cadmium), Cr (chromium), Cu (copper), Ni (nickel), Pb (lead), and Zn (zinc) concentrations in plants and soil were analyzed. The soils of the mining area was weakly alkaline and contained toxic levels of Sb, As, Pb, Cd, and Zn. Many plant species in the area (40 species and 19 families) have no clear signs of toxicity. The plants were divided into three categories (high, moderate, and low tendency to accumulate metals) based on their (ratio [RT], bioaccumulation factor [BCF], translocation factor [TF]) values. The plants with a high accumulation tendency exhibited the high potential to absorb Sb from contaminated soil; therefore, they can be used for the remediation or phytoremediation of Sb-contaminated soil. [ABSTRACT FROM AUTHOR]

China has the most abundant antimony (Sb) resources of any country in the world. Large quantities of Sb have been released from mining and smelting processes, causing serious Sb contamination in the mine or nearby areas. To understand the leaching characteristics of hazardous Sb, As, Pb and Cr from antimony minerals, 12 samples of antimony-bearing ores from eight large mines from China distributed in Hunan, Yunnan, Guizhou and Guangxi provinces were studied. The main compositions of these minerals are Sb 2 S 3 , SiO 2 or CaCO 3 . The pH changes during the leaching indicated that some minerals themselves are alkaline, providing sufficient acid neutralizing capacity during leaching. However, some alkaline minerals release much more Sb, As, Pb and Cr than others. Inconsistencies between totals amounts and the released content of Sb, As, Pb and Cr were also found. The surface topography of an antimony sulfide mineral and the species changes of Sb and sulfur (S) on its leached surface were also characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. It is the oxidation dissolution of Sb 2 S 3 that releases Sb. Sb(III) and S 2 − on the surface of the fresh mineral were oxidized to Sb(V) and S 2 O 3 2 − and SO 4 2 − , respectively, and finally, an equilibrium of dissolution was reached over time. The release of Sb, As, Pb and Cr from typical antimony ores is a source of Sb, As, Pb and Cr in the weathering zone; with this in mind, it is easier to understand the geochemical processes and the pollution accidents involving Sb and As within the mining areas and their surroundings. [ABSTRACT FROM AUTHOR]

• Sb concentrations varied with aquifers, whereas As differed seasonally. • Sb and As co-pollution types were identified by cluster analysis. • Mine activities have significant impacts on karst groundwater geochemistry. • Elevated SO 4 2− was related to Sb pollution indicated by tracing sulfate sources. The elevated levels of antimony (Sb) and arsenic (As) in groundwater caused by mine activities is of particular global concern. Understanding pollution mechanism of Sb and As related to mine activities and their influence on karst groundwater geochemistry is of great significance. However, it is still unclear. To address such questions, Sb and As and major ions, δ34S and δ18O of dissolved sulfate as well as δD and δ18O of water were analyzed for groundwater sampled from three main karst aquifers at the Xikuangshan (XKS) antimony mine from 2013 to 2017. Spatial and temporal variations of Sb and As of the three main karst aquifers were characterized as that, (1) Sb concentrations, rather than As, varied with aquifers, with high Sb (1–50 mg/L) of the D 3 s2 and C 1 y3 aquifers and low Sb (0.01–1.0 mg/L) of the D 3 x4 aquifer; (2) As concentrations had significant seasonal effect that was higher in winter and lower in summer, whereas Sb concentrations did not differ seasonally. Here we applied a recently developed cluster analysis method as well as geochemical indicators to identify pollution types of Sb and As in groundwater related to complex mine activities, and further to reveal main effects on karst groundwater geochemistry. The cluster analysis yielded a classification of four clusters, which was confirmed by principal component analysis. The groundwater of cluster 3 is of weakly alkaline HCO 3 -Ca type with low Sb (<0.015 mg/L) and low As (<0.005 mg/L), which is typical karst groundwater controlled by limestone dissolution. Whereas the other three clusters with high concentrations of Sb and As were identified to represent three pollution patterns dominated by oxidative dissolution of stibnite, leaching of mine wastes, and mixed pollution, respectively. Moreover, the effects of long-term mine activities on karst groundwater geochemistry are revealed, including: (1) Hydrogeochemical compositions of groundwater changed from HCO 3 -Ca type to SO 4 -Ca type. (2) Sulfuric acid significantly participated in carbonate weathering. (3) Weathering of silicate (main as silicified limestone) by H 2 CO 3 and H 2 SO 4 was accelerated. (4) Cation-exchange was enhanced to dominate groundwater geochemistry. Another striking finding is that sulfur and oxygen isotopes of sulfate can effectively distinguish sulfate sources related to mine activities and to trace Sb sources in karst groundwater. [ABSTRACT FROM AUTHOR]