Effects of sunlight, microbial activity, and temperature on the declines of antibiotic lincomycin in freshwater and saline aquaculture pond waters and sediments.

The residues of lincomycin (LIN), an antibiotic administered to aquatic animals, are often detected in aquatic environments. This study investigated effects of three environmental factors, sunlight, microbial activity, and temperature, on declines of spiked LIN in waters and sediment slurry samples collected from freshwater tilapia (Oreochromis mossambicus) and marine shrimp (Litopenaeus vannamei) culture ponds. The results showed that sunlight, temperature, and microbial activity all accelerated LIN transformation in the water and slurry samples. In matrixes of all water and slurry samples, LIN transformation was significantly faster under light conditions [half-life (t1/2) = 24-53 days] than under dark conditions (t1/2 = 154-2897 days). Microbial activity also accelerated LIN transformation; the t1/2 of LIN was shorter after nonsterile treatment (t1/2 = 12-809 days) than after sterile treatment (t1/2 = 154-2897 days). Moreover, LIN transformation was faster at 28 °C (t1/2 = 18-38 days) than at 20 and 12 °C (t1/2 = 34 and 462 days, respectively) in both slurry samples. The results revealed that LIN transformation in aquaculture pond water and sediment was either slow or stagnant. Sunlight, microbial activity, and temperature can accelerate LIN transformation to reduce LIN residue levels.