Metal concentrations in soil and invertebrates in the vicinity of a metallurgical factory near Tula (Russia)

Abstract

Summary To investigate the effects of emissions from a large metal works near Tula in the Russian Federation, we measured concentrations of iron, manganese, zinc, copper, nickel, lead and cadmium in soil, litter and invertebrates at four sampling sites at different distances from the factory. The sites were located in woodlands in the bed of the Voronka river, near the town of Kosaya Gora in the district of Tula. Additional soil properties (organic matter content, clay content, water holding capacity, Ca, Mg, N, P, and pH) were measured that could explain differences in the bioavailability of the metal burdens. It appeared that the factory is a source of Fe, Mn, Zn, Cu, Ni and Pb. One of the sampling sites had a high nitrogen content in the litter due to emissions from a fertilizer plant in the area. Most of the metal contamination was limited to the immediate surroundings and did not extend beyond a distance of 5 km. Only the site close to the factory can be considered as polluted, however, background concentrations of metals in the Tula area seem to be significantly lower than in present Western European soils and a reference system still has to be developed. Exchangeable metal concentrations (0.01 M CaCl 2 extracts from soil) were very low and were not correlated with the total concentrations, indicating low bioavailability of the pollution. At the most polluted site, concentrations of all metals were positively correlated with each other; correlations decreased with increasing distance. Metal concentrations in soil were often negatively correlated with organic matter content, especially so for nickel. Metal concentrations in invertebrates showed considerable variation between individual species, however, some general patterns were obvious. Concentrations were high in earthworms, oribatid mites and carabid beetles, and low in springtails, centipedes and spiders. There was no relationship between the trophic position of a species and its metal accumulating ability. Iron concentrations in invertebrates at the polluted site were a factor of 2 to 4 higher than at the most remote (reference) site; for zinc and copper the internal concentrations were also elevated, but to a lesser extent than the soil concentrations. The data illustrate the extremely complicated relationship between metal residues in invertebrates and metal concentrations in soil. For most of the saprophageous and predatory arthropods studied total concentrations nor exchangeable concentrations in soil are good predictors; species-specific feeding mechanisms and metal physiologies seem to be the main determinants.