Distribution of toxic elements between biotic and abiotic components of terrestrial ecosystem along an urbanization gradient: Soil,leaf litter and ground beetles

Urbanization and anthropogenic activities are the major source of environmental pollution which may cause damage in terrestrial ecosystems and their organisms. Toxic elements can accumulate in soil and leave tissue; thus, through the food chain they can accumulate in predatory organisms. The aim of our study was to investigate the effects of urbanization on toxic element concentration in soil, leaf litter and Carabus violaceus and Pterostichus oblongopunctatus specimens along an urbanization gradient. The studied predator species were common and their distribution is widespread along the urbanization gradient. Soil, leaf litter and ground beetles were collected from three forested area: urban park, suburban forest and rural forest. The following toxic element concentrations were analyzed in all samples: Al, Ba, Cd, Cu, Fe, Mn, Ni, Pb, Sr and Zn. In the soil there was no significant difference in toxic element concentration between areas, except in seasons. Significantly higher toxic element concentration was found in autumn than in spring in the soil. In the case of leaf litter we found significant differences between areas in the following toxic elements: Ba, Cu, Mn, Sr and Zn. The concentrations of all elements were significantly higher in autumn than in spring. Significantly higher concentration was found in P. oblongopunctatus specimens than in C. violaceus for all studied elements, except Sr. We found significant differences in elemental concentrations between sexes in both species. Significantly higher Cu and Pb concentration was found in male beetles than in female ones. Just the opposite was true for the Sr concentration. We found positive correlation between toxic element concentration of C. violaceus and leaf litter for Mn and Zn. Negative correlations were found between toxic elements of ground beetles and soil for Al, Ba, Fe, Sr and Zn. Our study confirms that different breeding strategies and sexes cause differences in the accumulation of toxic elements. In summary, we demonstrated that ground beetles, leaf litter and soil were suitable bioindicators for monitoring the effects of urbanization and anthropogenic activities on terrestrial ecosystem.