Dissipation of sulfamethoxazole, trimethoprim and tylosin in a soil under aerobic and anoxic conditions

Environmental context. Wide application of antibiotics in the treatment of human beings and animals has led to increasing concern about their safe disposal. After use, antibiotics may enter the soil environment via disposal of wastes such as biosolids and animal manure. We investigated the biotic and abiotic factors that influence the dissipation in soil of three commonly used antibiotics sulfamethoxazole, trimethoprim and tylosin. Abstract. Antibiotics could enter soil via application of biosolids as fertilisers, thus resulting in soil contamination. This study investigated the persistence of sulfamethoxazole, trimethoprim and tylosin in a soil under aerobic and anoxic conditions. The dissipation of the antibiotics in the soil followed first-order reaction kinetics. The half-lives of sulfamethoxazole, trimethoprim and tylosin were 2, 4 and 8 days in non-sterile soil under aerobic conditions respectively. Under anoxic conditions, their half-lives in non-sterile soil were 7, 11 and 16 days respectively. Sulfamethoxazole and trimethoprim dissipated more rapidly in non-sterile soil than in sterile soil. Biodegradation played a major role in the dissipation of sulfamethoxazole and trimethoprim in the soil. No significant difference was found for tylosin between the sterile and non-sterile treatments under both aerobic and anaerobic conditions, suggesting that abiotic factors were responsible for the dissipation of tylosin in the soil.