Microbiological characteristics of soils contaminated with heavy metals

In this study, total heavy metal contents and their relationships with soil microbiological characteristics were investigated in agricultural soils which were with polluted heavy metals. Total heavy metal content of the soils varied from 0.95 to 3.20 μg Cd g–1, 17.10 to 42.33 μg Co g–1, 18.43 to 141.18 μg Cr g–1, 23.05 to 96.68 μg Cu g–1, 19.30 to 144.15 μg Pb g–1 and 76.10 to 210.43 μg Ni g–1. Soil dehydrogenase, catalase and urease activity, basal soil respiration and microbial biomass-C were 23.9–420.4 μg TPF g–1 dry soil, 2.7–61.1 ml O2 5 g–1 dry soil, 16.9–749.3 μg N g–1 dry soil, 4.8–33.7 mg CO2 100 g–1 dry soil and 3.8–135.4 mg CO2–C 100 g–1 dry soil in agricultural soils of Bafra and Çarşamba Plain, respectively. The soil organic carbon content showed significant correlation with the dehydrogenase activity, catalase activity, basal soil respiration, and microbial biomass-C at P < 0.01. Urease activity was strongly correlated with clay content and cation exchange capacity (CEC), but not significantly correlated with organic C content. With the exception of urease activity, generally significant negative relationships were observed between the total heavy metal contents and soil microbiological characteristics. Thus, these microbiological characteristics could be used as indicators to evaluate the heavy metal contamination of agricultural soils.