Activity and functional diversity of microbial communities in long-term hydrocarbon and heavy metal contaminated soils

The impacts of long-term polycyclic aromatic hydrocarbons (PAHs) and heavy metal pollution on soil microbial communities functioning were studied in soils taken from an old coke plant. The concentrations of PAHs in the tested soils ranged from 171 to 2137 mg kg(-1). From the group of tested heavy metals, concentrations of lead were found to be the highest, ranging from 57 to 3478 mg kg(-1), while zinc concentrations varied from 247 to 704 mg kg(-1) and nickel from 10 to 666 mg kg(-1). High dehydrogenase, acid and alkaline phosphatase activities were observed in the most contaminated soil. This may indicate bacterial adaptation to long-term heavy metal and hydrocarbon contamination. However, the Community Level Physiological Profiles (CLPPs) analysis showed that the microbial functional diversity was reduced and influenced to a higher extent by some metals (Pb, Ni), moisture and conductivity than by PAHs.