【摘要】 为阐明磺胺二甲基嘧啶（SM2）与镉（Cd）对生菜（LachicasativaL.）的单独和复合毒性效应及其毒性机制,采用随机区组试验研究了水培条件下,SM2(0、0.5、2、10 mg·L^-1)与Cd(0、1、5 mg·L^-1)单一和复合污染对生菜种子发芽、幼苗生长和污染物积累的影响。结果表明,单一SM2处理对生菜幼苗根伸长具有一定的毒性效应,与对照相比,单一SM2处理下,随SM2质量浓度的增加(0.5-10 mg·L^-1),根长抑制率增加了11.51%-51.87%;但单一SM2处理对生菜发芽率、生物量则无显著影响。而单一Cd处理对生菜发芽率、根生物量以及根伸长均无显著影响。Cd的加入可以增强SM2对生菜的毒害作用,与10 mg·L^-1 SM2处理相比,10 mg·L^-1 SM2+5 mg·L^-1 Cd处理的发芽率降低了7.14%;加入1、5mg·L^-1Cd后SM2的根伸长半抑制浓度IC50分别降低了7.89%、23.68%。单一污染条件下,生菜对Cd/SM2的积累随污染物质量浓度的增加而增加。低浓度Cd处理(1 mg·L^-1)条件下,加入SM2可显著降低生菜根系和地上部Cd含量,但是对于高浓度Cd(5 mg·L^-1),加入SM2可以增加根系和地上部Cd积累量。低浓度SM2(0.5、2 mg·L^-1)条件下,加入Cd可显著促进生菜根部SM2的累积,但高浓度SM2(10mg·L^-1)条件下,Cd的加入却显著降低生菜根部SM2的累积。SM2处理下,Cd的加入对生菜地上部SM2的积累无显著影响。SM2/Cd在生菜中的富集和迁移受其性质、投加量及质量浓度组合影响,复合污染下生菜对Cd的积累能力在较高Cd质量浓度时表现出协同作用,而对SM2的积累能力则在相对低质量浓度时表现出协同作用。这可能与Cd和SM2复合存在条件下会形成络合物,以及络合物对生菜产生的毒性效应有关。更多还原

【Abstract】 Randomized block experiments were conducted to research the effects of single and combined pollution of sulfamethazine(SM2, 0, 0.5, 2, 10 mg·L^-1)and cadmium(Cd, 0, 1, 5 mg·L^-1) on seed germination, growth and pollutant accumulation in Lachica sativa L. under hydroponic conditions, so as to elucidate the single and combined toxicity of sulfamethazine（SM2） and cadmium（Cd） on Lachica sativa L. and its toxic mechanism. The results showed that single SM2 treatment had some toxic effect on root elongation of Lachica sativa L. seedlings. Compared with the control, the inhibition rate of root elongation increased by 11.51% and51.87% with the SM2 treatment at concentration of 0.5 mg·L^-1 and 10 mg·L^-1. While single SM2 treatment had no significant effect on the germination rate and biomass of Lachica sativa L.. Adding Cd could enhance the toxic effect of SM2 on Lachica sativa L..Compared with 10 mg L^-1 SM2 treatment alone, the germination rate of 10 mg·L^-1 SM2+5 mg·L^-1 Cd treatment decreased by 7.14%,and the semi-inhibitory concentration（IC50） of SM2 on root elongation decreased by 7.89% and 23.68% respectively, with adding 1 and 5 mg·L^-1 Cd. The accumulation of Cd/SM2 in Lachica sativa L increased with the increased addition of Cd/SM2 under the single pollution of Cd or SM2. Under low concentration of Cd treatment(1 mg·L^-1), the content of Cd in roots and shoots of Lachica sativa L. was significantly decreased by adding SM2. While the accumulation of Cd in roots and shoots was increased by adding SM2 with high concentration of Cd(5 mg·L^-1). Cd-SM2 composition could inhibit the accumulation of Cd in Lachica sativa L., but promote when the concentration of Cd was 5 mg·L^-1. Under low concentration of SM2(0.5 mg·L^-1 and 2 mg·L^-1), the accumulation of SM2 in the roots was significantly promoted by Cd addition, whereas under high concentration of SM2(10 mg·L^-1), the accumulation of SM2 in the roots was significantly reduced by Cd addition. Meanwhile, there was no significant difference in the accumulation of SM2 in aerial portion between single SM2 and compound pollution. These results indicated that the accumulation and migration of SM2/Cd in Lachica sativa L. were affected by its properties, dosage, mass concentration and complex reaction. The accumulation of Cd in Lachica sativa L. under combined pollution showed synergistic effect at higher Cd concentration with SM2 combined pollution, while the accumulation of SM2 Lachica sativa L. under combined pollution showed synergistic effect at lower SM2 concentration with Cd combined pollution. This may be related to the formation of complexes in the presence of Cd and SM2, and the toxic effect of complexes on Lachica sativa L..更多还原