Abstract

The multi-compound pollution of soils affected by industrial emissions has a negative impact on soil biological activity. We analyzed the relationship of the published composition of nematode communities and microbial properties in topsoil samples from 11 sampling locations along a 20-km deposition gradient downwind of the Angren industrial area (Uzbekistan) with pollutant concentrations (Figure 1). The considered pollutants included 10 metals, 31 polycyclic aromatic hydrocarbons (PAHs) and 12 oxygenated PAHs (OPAHs, all data taken from previous work). Most of the pollutant concentrations showed strong collinearity. The total number of soil free-living nematodes (TNEM, 9 – 1129 individuals 100 g-1 soil), specific nematode trophic groups (fungivore, plant parasitic, omnivore) and metabolic coefficients (qCO2 = basal respiration (RB)/Cmic, 0.17-4.74) were significantly negatively correlated with the concentrations of several of the studied pollutants. The same was true for trophic diversity and the Shannon-Weaver diversity index of the nematode community. The number of TNEM and fungivore nematodes correlated positively with the concentrations of 9-fluorenolsuggesting that this is a metabolite of some nematodes. RB and qCO2 seemed to be stimulated by a number of PAHs and OPAHs and qCO2 additionally by U. A variable selection procedure of individual compounds suggested that various PAHs, OPAHs and Pb had the strongest negative impact on the measured biological properties. When only compound group concentrations were used as explanatory variables, exclusively sums of parent-PAHs concentrations (3-, 4-, 5-, 6- and 7-ring) were selected for nematode-related properties and trophic diversity. Our results tentatively suggest that the PAHs affected nematode community composition and microbial properties most strongly followed by OPAHs and metals.