Sources of natural and anthropogenic sulphur around the Teruel power station, NE Spain. Inferences from sulphur isotope geochemistry

Stable sulphur isotopic ratios were used for the identification of sources of atmospheric sulphur compounds, and the assessment of their contribution to the atmospheric sulphur deposition load around a coal-fired power plant in NE Spain. The study consists of a number of stages: identification of the sources, clarification of the chemical pathways of the sulphur from these sources, assessment of their contribution to the overall load, and determination of the emission impact on the natural sulphur cycle in the area. Sulphur isotope analyses were carried out on bedrock and sediment samples, surface and groundwater, wet-only and total deposition, total suspended particles and SO2 emissions from the power plant. The results are useful in indicating the sources of sulphate in the atmosphere, allow us to exclude some other potential sources, and demonstrate that: (a) the total load of sulphate is largely unaccounted for by Cl and is, therefore, of non-sea spray origin; (b) this excess sulphate does not originate from bedrock and sediments in the area; (c) there is a significant contribution of sulphur from remote sources such as the Atlantic–north European areas; (d) the multitude of local and remote sources involved and the rapid change in their relative contribution do not facilitate the quantification of the deposition derived from the emissions of the power station. However, given the low conversion efficiency and the relative constancy of the δ34S of the emitted SO2 it is suggested that sulphate deposits with δ34S of around 2.5‰ originate from the Teruel power station.