Uptake of three sulfonamides from contaminated soil by pakchoi cabbage.

Uptake of three sulfonamides (SAs) including sulfadiazine (SDZ), sulfamethazine (SM2) and sulfamethoxazole (SMZ) by pakchoi cabbage from soil was evaluated by using pot experiment. SDZ, SM2 and SMZ spiked in soil could be taken up by pakchoi cabbage. SM2 and SMZ were accumulated more easily by pakchoi cabbage than SDZ. The dissipation half-lives of SMZ (16.8d) and SM2 (16.7d) in soil were significantly longer than SDZ (10.8d). The higher concentrations of SM2 and SMZ in pakchoi cabbage in comparison with that of SDZ could be attributed to the higher residual concentrations of SM2 and SMZ in soil. Increasing initial concentration of SM2 spiked in soil, the residual concentration of SM2 in soil increased and resulted in promoting SM2 uptake in pakchoi cabbage. Concentrations of SAs in pakchoi cabbage planted in combined sulfonamides polluted soil differ from that in single sulfonamide polluted soil, although the same concentration (5.0mg/kg) of SAs was spiked in soil. Combined SAs pollution in soil may enhance SAs uptake in pakchoi cabbage. The lower bacteria numbers in soil under combined pollution resulted in higher residual SAs concentrations in soil, which could be the main reason for higher SAs concentrations in pakchoi cabbage.