Bioconcentration and elimination of sulfamethazine and its main metabolite in sturgeon (Acipenser schrenkii).

A steady-state bioconcentration and elimination of sulfamethazine (SM(2)) in the sturgeon (A. schrenkii) was conducted in flow-through aqueous conditions. Two treated groups of fish were exposed to concentrations of 1.00 and 0.10 mg/L of SM(2), respectively. SM(2) and its main metabolite, N(4)-acetyl-SM(2), were determined in both fish muscle and water during the 8-day uptake period and the subsequent 6-day elimination period. Rapid uptakes of the drug were observed in both treated groups. Muscle tissue residues plateaued after approximately 3 days. The bioconcentration factor in muscle (BCF(m)) in the low-concentration drug solution was 1.19 and that in the high-concentration-treated level was 0.61. The calculated biodegradation index was 3.72%. The elimination half-times (t(1/2)) of the two treatment levels were 19.44 and 23.52 h, respectively. The result indicates that SM(2) will neither bioconcentrate in individual aquatic organisms nor biomagnify in the food chain, although the BCF(m) was relatively higher under the low-concentration exposure.