Stable sulfur and oxygen isotopes of sulfate as tracers of antimony and arsenic pollution sources related to antimony mine activities in an impacted river

Abstract

Listen

Translate article

Source identification of antimony (Sb) and arsenic (As) pollution associated with mine activities is crucial for pollution prevention and control, but is still challenging. A typical river at the Xikuangshan antimony mine affected by known mine activities along the runoff, including mining, beneficiation and smelting, may allow to test the possibility and reliability of stable isotopes of sulfate (δ34SSO4 and δ18OSO4) as tracers to identify Sb and As sources associated with mine activities. The river water and mine wastewater samples were chemically and isotopically characterized in the dry and rainy season respectively. As expected, the concentrations of Sb, As and SO42− in the river increased and varied with the seasons. The spatial and seasonal variations of Sb, As and SO42− concentrations in the river were consistent with the mixing of the mine wastewater discharged into the river. Moreover, the impact of mine activities resulted in the correlations of Sb, As and SO42− of the river water high in the rainy season but low in the dry season. The sulfur and oxygen isotopic compositions of SO42− of the river fell within the range composed of upstream river and its received mine wastewater. The estimated proportional contributions of multiple mine activities to the river by a Bayesian isotope mixing model suggested that the total contribution of the mine activities ranged from 37 ± 10% to 96 ± 4% in the dry season and from 28 ± 8% to 88 ± 8% in the rainy season. The leachate of waste rocks and smelting slag dumps was the predominant contributor in the upper section, with the proportions greater in the dry season (37 ± 9%∼76 ± 12%) than in the rainy season (28 ± 8%∼56 ± 9%). The mining drainage became the primary source (69 ± 8%∼80 ± 8%) in the lower section in the dry season, whereas all sources contributed approximately equally in the rainy season. Leakage from the tailings pond (19 ± 13%) is another important source in the rainy season. This study demonstrated that sulfur and oxygen isotopes can be effective for source identification and qualification of multiple mine activities on Sb and As pollution in the river, which provides new insights into source apportionment of metal(loid)s pollution related to complex mine activities.