RESUMO
Aims: To study the effect of various doses of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) on the enzymatic (DHA, acid phosphatase, alkaline phosphatase, urease and catalase) activity in sewage amended and un-amended alluvial soil. Methodology: A laboratory incubation study was conducted during 2012-2013 on an Aligarh farm alluvial soil. The enzymatic activity was studied in presence of various doses of three tetracycline antibiotics in soil; soil amended with sewage sludge; and mixture of sewage sludge and tetracyclines at different time intervals [(0 (4h), 7, 14, 21, 35, 56, 70,91d]. Results: Activity of all the studied enzymes was significantly inhibited for up to 14-21 days of incubation (14 d for DHA and acid phosphatase, 21 d for alkaline phosphatase, urease and catalase) and thereafter inhibition got weaker. The activity of all the studied enzymes decreased with increase in the doses of tetracyclines. Higher enzymatic activity was observed in sewage sludge amended soil than in the un-amended soil. Tetracyclines in presence of sewage sludge were found to have no appreciable effect on enzymatic activities. Conclusions: Dehydrogenase, acid and alkaline phosphatase, urease and catalase activity in tetracycline free soil was superior to soil containing antibiotics in the period of 2-3 weeks of incubation. The inhibition of soil enzyme activity was directly proportional to tetracycline concentration. In presence of sewage sludge, the studied enzymes activity initially increased up to 3 weeks and decreased thereafter. In presence of sewage sludge and antibiotics, the activity of enzymes remains almost unchanged. The activity of studied enzymes in soil was positively correlated to soil organic content.
RESUMO
The present study has been undertaken to know the effect of concentrations of lead (Pb) and different organic materials on the maize yield, concentrations of lead on maize plants and diethylene triamine penta-acetic acid (DTPA) extractable lead (Pb) on the post harvested soils. The results revealed that growth of maize increased by adding lead (Pb) upto 25 mg kg(-1) soil and thereafter the growth decreased. Application of organic matter increased the growth of maize in Pb-contaminated soil. With the increase in Pb concentration in soil, the concentration of Pb in plants also increased, however, application of organic material decreased Pb concentration in maize. The concentration of DTPA extractable lead (Pb) in post harvested soil samples significantly and consistently increased with increase in Pb. The addition of organic manure decreased the DTPA extractable Pb in soil which might be due to complexation/chelation of Pb with organic matter.