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The increased use of antibiotics has raised concern regarding the environmental impacts of antibiotic residues in soil. In this study, we performed a laboratory experiment to compare the effect of two antibiotics: polymyxin B and penicillin G on the activity of alkaline phosphatase, acid phosphatase, dehydrogenases, and urease, in sandy loam and loamy sand. Antibiotics were applied to soil samples at the dosages: 2, 20, and 200 mg/kg DM. Soil without antibiotics was used as a control sample. The results showed that the contamination of soil with antibiotics affects the soil enzymes. Polymyxin B caused greater changes in enzyme activities than that of penicillin G. Moreover, greater changes in soil enzyme activities were observed in loamy sand than in sandy loam. Phosphatases were the most sensitive to the soil contamination with antibiotics. Principal component analysis showed that dehydrogenases were the most negatively correlated with PC1. [ABSTRACT FROM AUTHOR]

The increased use of antibiotics has raised concern regarding the environmental impacts of antibiotic residues in soil. In this study, we performed a laboratory experiment to compare the effect of two antibiotics: polymyxin B and penicillin G on the activity of alkaline phosphatase, acid phosphatase, dehydrogenases, and urease, in sandy loam and loamy sand. Antibiotics were applied to soil samples at the dosages: 2, 20, and 200 mg/kg DM. Soil without antibiotics was used as a control sample. The results showed that the contamination of soil with antibiotics affects the soil enzymes. Polymyxin B caused greater changes in enzyme activities than that of penicillin G. Moreover, greater changes in soil enzyme activities were observed in loamy sand than in sandy loam. Phosphatases were the most sensitive to the soil contamination with antibiotics. Principal component analysis showed that dehydrogenases were the most negatively correlated with PC1. [ABSTRACT FROM AUTHOR]

This paper presents the comparison of changes in the enzyme activities involved in carbon, phosphorus, and nitrogen cycle in soil exposed to volatile organic compounds (VOCs) emitted from creosote-treated wood. The laboratory experiment was carried out on two soil samples: loamy sand (Corg8.71 g kg* ', pHkci 6.36) and sandy loam (Corg10.92 g kg1, PHkci6.81). The soil samples were incubated with ground sleepers impregnated with creosote. After 21 days of incubation, in the soil samples the activities of dehydrogenases, catalase, β-glucosidase, o-diphe-nol oxidase, lipase, acid phosphomonoesterase, alkaline phosphomonoesterase, phosphodiesterase, phosphodiesterase, inorganic pyrophosphatase, urease, nitrate reductase, and proteases were determined. VOCs emitted from the creosote-treated wood significantly changed activities most of the soil enzymes. Increase in activity was found for dehydrogenases (in both soil types) and lipase (in loamy sand). The highest inhibition was observed for inorganic pyrophosphatase, nitrate reductase, and proteases. Calculated values of resistance index showed that among the measured enzymes involved in carbon, phosphorus, and nitrogen cycle, dehydrogenases, inorganic pyrophosphatase, and proteases were the most sensitive to VOCs, respectively. [ABSTRACT FROM AUTHOR]