Impact assessment of heavy metal pollution on soil mite communities (Acari: Mesostigmata) from Zlatna Depression – Transylvania

Abstract

Abstract The heavy metal pollution level of soil from twelve grasslands and its impact on soil mite communities was assessed. The impact assessment was investigated, taking into account the distance from pollution source, the degree of pollution and the cumulative influence of heavy metals and other environmental variables. These variables were: temperature, humidity, acidity, carbon content, nitrogen total, C/Nt ratio, slope, altitude, vegetation cover, exposition and soil type. The measured concentrations of all heavy metals for the investigated grasslands exceeded the reference values according to the national legislation. In order to make a comparison between investigated grasslands and in order to classify the ecosystems, total metal load was calculated. Three groups of grasslands were established based on different degrees of soil pollution and taking into account the total metal load. In total, 66 Mesostigmata species were identified, with 961 individuals. Mite communities from the most polluted areas were distinguishable from those from less polluted grasslands. Some heavy metals (e.g. As, Cu, Pb and Zn) influenced the soil mites from highly polluted ecosystems, while Mn and other environmental variables (altitude and soil humidity) were strongly correlated with invertebrate communities from the medium polluted areas. Soil temperature was the main factor influencing mites from the less polluted ecosystems.