Microorganisms in soils with elevated heavy metal concentrations in southern Serbia

Abstract

Soil chemical properties and total heavy metal concentrations (As, Cd, Cr, Cu, Ni, Pb, Zn, Fe and Mn) and their relationships with some soil microbiological characteristics (such as soil respiration and numbers of specific groups of microorganisms) were evaluated in agricultural soils in southern Serbia. In 42% of samples, slightly elevated concentrations of As, Ni and/or Pb were detected, with the highest values of 43.4, 64.4 and 184.1 mg/kg, respectively. No significant differences were observed in soil microbiological characteristics between soil samples with elevated heavy metals and heavy metals below the maximum allowed concentrations (MAC). There was no negative correlation between any of the heavy metals and any microbiological characteristics, except the total number of fungi and the concentration of Ni (r=-394). Positive correlations between most of the heavy metals and the number of Azotobacter were obtained. Correlation analysis and stepwise multiple regression analyses indicated that the chemical properties of the soil are the factors that affected the number of microorganisms the most. The content of CaCO3 significantly contributed to variations in soil respiration (39%), the total number of microorganisms was affected the most by humus (53%), oligonitrophiles by the total N content (49%), while the numbers of actinomycetes and fungi were affected by the pH (48% and 58% of the variation). [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR37006]

Keywords

• soil quality
• heavy metals
• microbial community
• soil respiration
• agroecosystems