Impact Assessment of Soil Contamination with Antibiotics (for Example, an Ordinary Chernozem)

An increase in the penetration of metal-based nanoparticles (NPs) into the environment requires an assessment of their ecotoxicity as they impair the critical activity of plants, animals, bacteria, and enzymes. Therefore, the study aimed to observe the effects of metal-based NPs, including copper (Cu), nickel (Ni), and zinc (Zn), on the Cambisols, which cover a significant part of the earth’s soil and play an important role in the biosphere. Metal-based NPs were introduced into the soil at concentrations of 100, 1000, and 10,000 mg/kg. The biological properties of the soil are being investigated as the most sensitive to external contamination. The highest ecotoxicity of the studied pollutants introduced into the soil at the same concentrations was shown by Cu (up to 34%) and Zn (up to 30%) NPs, while Ni NPs showed less (up to 22%). Microbiological (total number of bacteria, Azotobacter sp. abundance) and phytotoxic properties (radish seed germination and length of roots) of Cambisols were more sensitive (22–53%) to pollution by NPs of Cu, Zn, and Ni, while enzymatic activity (catalase and dehydrogenases) showed less sensitivity (14–32%). The present results could be useful for biomonitoring the state of contaminated soils, especially by NPs.

Thallium (Tl) was introduced into Haplic Chernozem in the amounts of 3, 30, and 300 mg/kg, and biological indicators were observed at 10, 30, and 90 days after incubation in the laboratory experiment. An increase in biological activities; i.e., the total number of bacteria, Azotobacter spp. abundance, enzymes (catalase, dehydrogenases), and phytotoxic indicators (germination rate of radish) after 30 days of Tl exposure were noted. The total number of bacteria and Azotobacter spp. abundance, enzyme activity, and phytotoxicity were more sensitive (16–76%) and informative (12–65%) indicators compared to the control, respectively. Integral biological indicators of soil state (IIBS) noted at 10, 30, and 90 days decreased at a dose of 30 and 300 mg/kg by 13–43% in relation to the control. An increase in Tl concentration and duration of exposure (up to 90 days) inhibited biological properties and caused ecotoxicological effects, respectively. We concluded that the use of individual indicators served as an indicator of the state of the soil.

In recent years, the input of antibiotics into soils has sharply increased. We studied the impact antibiotics (benzylpenicillin, pharmasin, and nystatin) at different concentrations (100 and 600 mg/kg) on population densities of microorganisms and enzymatic activity of ordinary chernozems in model experiments. The applied doses of antibiotics had definite suppressing effects on population densities of microorganisms (up to 30–70% of the control) and on the soil enzymatic activity (20–70% of the control). Correlation analysis showed close correlation between the concentrations of antibiotics and the population densities of soil microorganisms (r = −0.68–0.86). Amylolytic bacteria had the highest resistance to the antibiotics, whereas ammonifying bacteria had the lowest resistance. Among the studied enzymes belonging to oxidoreductases and hydrolases, catalase and phosphatase had the highest and the lowest resistance to the antibiotics, respectively. The effect of antibiotics on the biological properties of the chernozem lasted for a long time. The studied parameters were not completely recovered in 120 days.