Metalloid Contaminated Microhabitats and their Biodiversity at a Former Antimony Mining Site in Schlaining, Austria

Abstract

This paper is on the biological impact of arsenic and antimony on the flora and microflora on a former Sbmining site in Schlaining (Stadtschlaining, Burgenland, Austria). Several habitats were investigated with respect to biodiversity and metalloid contamination in soil. Although the overburden of the mining activity had been remediated less than ten years ago, metalloid concentrations occurred in soil up to 1.4 As and 3.6% Sb, respectively, in some microhabitats, as determined by Instrumental Neutron Activation Analysis. These metalloids were embedded into a nonuniform mineralogical background. Metalloid mobility could not be explained by common models, indicating that predictions on the mobility of geogenic metalloids require additional mineralogical data. The biological effects of this contamination were variable. We observed that metalloid resistant strands of microorganisms appeared in the contaminated soil. In cultivation experiments, Sb was found to be more toxic than As. Sulphur oxidising strand were more resistant than organotrophic ones and grew even better on cultivation media spiked with 10 ppm As than on the unspiked control. The flora was only partially influenced: the lowest biodiversity was found in metalloid richest soils, but moderate contamination resulted in enhanced species numbers. Only in one case, where the pH-buffering capacity of the soil was exceeded by consumption of the entire carbonate, no embryophytes occurred. This was probably due to extreme pH conditions as well as to metalloid concentrations. Our data support the hypothesis that higher plants are rather affected by extreme soil conditions, which often coincide with As contaminations, than by the contamination itself. A small rivulet in this area contained 26 g/l and thus exceeded the WHO guideline value for As in drinking water by a factor of 2.6. Indeed we observed a diminished biodiversity in this rivulet.