Abstract

EFFECT OF BIOCHAR AMENDMENT AND AGEING ON SORPTION AND DISSIPATION OF TETRACYCLINE’S IN SOILS

*Dr. O. P. Bansal

Abstract

This study pertains to investigate the effects of biochar an environmental friendly soil amendment used to enhance the soil fertility on the sorption dissipation and mobility of three tetracycline antibiotics, viz., chlortetracycline (CTC), oxytetracyline (OTC) and tetracycline (TC) on six agricultural field soil samples collected from different parts of India. The results of the study revealed that with the increase in TCs concentration the sorption of TCs increased in both the bulk soils and biochar amended soils denoting that process of TCs sorption is influenced by the soil properties mainly organic carbon and CEC. The sorption of TCs was significantly increased in presence of biochar which might be attributed to availability of sorption sites on biochar and the presence of micro pores in biochar. However, the sorption retards in aged biochar amended soils which might be due to covering of micro pores by organic and inorganic substances and oxidation of functional groups on the biochar surface. The adsorptive capacity of soils was in order soil No. 3 > 5 > 2 > 4 > 1 > 6. The adsorption capacity was significantly positively correlated with the amount of biochar amended. The interaction between TCs and biochar might occur via multiple bonding mechanisms including ionic bond between negative charged organic matter and positively charged TCs and/or hydrogen bonds in between TCs and organic matter. The sorption data of un- amended and biochar amended soils were best fitted in Freundlich adsorption equation and the adsorption isotherms were of ‘L’ type. The TCs dissipation in all the substrates followed the first order rate equation and DT50 ranged in between 34.3 to 58.7 d. Soils amended with biochar enhanced the stability of TCs and reduced their mobility. The concentration of TCs below 10 cm after 91 days of application in biochar amended soils was 70% lesser than un-amended soil. The dissipation in soil environment was slow, indicating that these compounds may persist in soils.

Keywords: Antibiotics, compost, DT50, organic carbon, soils.