Effect of methanotrophic activity on biodegradation of thiobencarb in contaminated soil

Abstract

To investigate the effects of methanotrophic activity on biodegradation of thiobencarb in contaminated soil and environmental factor on thiobencarb degradation. Various environmental conditions were investigated the degradation rate of methanotrophs-rich soils were compared with that of methanotrophs-poor soils at all environmental conditions. The results indicated that methanotrophs-rich soils had the degradation rate of thiobencarb higher than methanotroph poor-soils had at all environmental conditions, and the degradation rate of thiobencarb was the first order reaction. Increasing thiobencarb concentrations from 2.10 to 14.87 µg per g soils resulted in increasing methane oxidation rate, and increasing thiobencarb degradation rate implying that not only several microorganisms in soil can degrade thiobencarb, but methanotrophs also involve in degradation of thiobencarb in soil. The maximum degradation rate and minimum half-live, at 14.87 µg THB per g, were 0.801 µg THB per g soil.day and 9.24 days, respectively. Addition nitrate fertilizer from 22.83 to 96.30 µg NO3- per g result in decrease methane oxidation rate and thiobencarb degradation rate. The maximum degradation rate and methane oxidation rate were found at 22.58 µg NH4+ per g. The optimal moisture content, temperature and methane content for thiobencarb degradation were 20% MC, 38-40 C, 10% (v/v), respectively. Increasing nitrate content ≥96 µg NO3- per g could inhibit degradation of thiobencarb.