Antimony (Sb) is widely used as additivie in alloys, ceramics, glass and plastic products in modern industries. As a metalloid element with potential toxicity and carcinogenicity, Sb pollution in soil and groundwater has seriously threatened to the human environment for the combustion of fossil fuel and waste containing Sb and a series of mining activities. Recent years, Sb isotope technology is used as a new perspective to identify pollution source and reveal its migration and transformation.
In this study, Sb isotopic composition of river water and groundwater collected in mining area was determined by MC-ICP-MS (Multi-Collector Inductively Coupled Plasma Mass Spectrometer). A method of preconcentration and purification was developed and optimized based on the use of a silica-based thiol resin column, which achieves a quantitative recovery of Sb (at least 95%). When SPEX (dissolution of Sb ore) and GSB were used for in-house standard materials of Sb isotope measurement, it was demonstrated that there was little Sb isotope fractionation in the proposed method, which the ε123Sb falls in the -0.1 to -0.4 level. Therefore, the method for the preconcentration and purification of Sb is effective for isotope analysis. Indium (In) was used as an internal standard for correction of the instrumental mass discrimination occurring in the MC-ICP-MS instrument. Under the conditions of Apex injection, the ε^123^Sb value for in-house standard solution and water samples could be determined with a reproducibility (or external precision) of 0.04‰.
The isotopic composition of the selected water samples shows a variation of 2 to 3ε units. One groundwater sample showing light isotope enrichment contrasted Sb isotopic signature of others samples containing river water and groundwater, which could be related to various biogeochemical processes when Sb transfers from rocks, mine wastes and sediments to the water compartment. This result shows that Sb isotope technology may be useful in tracking pollution sources and biogeochemical processes in hydrologic systems.
Due to the limited water samples and the absence of leachate from tailings pond and waste heap, a small isotopic variation of samples was observed. Now the digestion procedure for ore samples especially for stibnite and slags is developing and optimizing, so the relationship between potential source of Sb and water environment can be established in the near future. Assuredly the processes (dissolution, oxidation, precipitation and adsorption) may generate fractionation during Sb transports from ore material into the water environment, and these part of the related experiments will continue to be carried out as soon as possible.