环丙沙星和镉复合污染土壤中镉的生物可给性及其动态变化

Bioaccessibility and dynamic dissolution of cadmium from compound-contaminated soils containing cadmium and ciprofloxacin

为研究环丙沙星(CIP)和镉(Cd)复合污染土壤中Cd的生物可给性,通过向无污染土壤中添加不同浓度的环丙沙星(对照:0 mg·kg^(-1),Ⅰ:5 mg·kg^(-1),Ⅱ:25 mg·kg^(-1),Ⅲ:50 mg·kg^(-1))和Cd(80 mg·kg^(-1))进行老化实验,运用in vitro和SHIME模型评估老化后土壤Cd的生物可给性。结果表明:不同老化天数(第1 d:D1,第30 d:D30,第60 d:D60)复合污染土壤中Cd的生物可给性有所差异。随着土壤老化时间的延长,重金属Cd的生物可给性不断降低,表现为(D600.05);D1和D30小肠阶段Cd的生物可给性呈逐渐降低的趋势,D60小肠阶段Cd的生物可给性呈增加的趋势;在结肠阶段,D30和D60各处理(D30 CIPⅠ+Cd处理除外)Cd的生物可给性均高于对照处理,且CIPⅢ+Cd处理达到最大。胃阶段不同停留时间(20、40、60 min)Cd生物可给性动态变化结果显示,60 min时Cd的生物可给性达到最大,20 min时各处理土壤中Cd的生物可给性变幅最大,Cd的生物可给性在胃阶段不同停留时间变化呈先快后慢趋势。研究表明,环丙沙星和Cd复合污染土壤中Cd的生物可给性在胃阶段较高,在小肠和结肠阶段较低。环丙沙星的添加对胃阶段Cd的生物可给性无显著影响,而对小肠和结肠阶段Cd的生物可给性有一定的影响,与未添加环丙沙星的对照处理相比,添加25、50 mg·kg^(-1)环丙沙星显著提高了老化30 d结肠阶段和老化60 d小肠阶段Cd的生物可给性。

To understand the bioaccessibility of cadmium(Cd)in compound-contaminated soils containing cadmium and ciprofloxacin,uncontaminated soils were artificially polluted with cadmium and ciprofloxacin at 4 different treatment rates(CK:0 mg·kg-1,CIP:Ⅰ5 mg·kg-1,Ⅱ25 mg kg-1,andⅢ50 mg kg-1;Cd:80 mg·kg-1).A pot experiment was performed with three soil aging times to investigate the risk of Cd to human health using in vitro digestion method and SHIME model.The results showed that there was no significant difference in the bioaccessibility of Cd among different soil aging times in compound-contaminated soils.Besides,the bioaccessibility of Cd decreased with soil aging time(D60<D30<D1).There was no significant difference in bioaccessibility of Cd,in the gastric phase,within the four treatments and among the soil aging times.With the increase in concentration of ciprofloxacin in compound-contaminated soils,the bioaccessibility of Cd differed between D1,D30,and D60 but no significant differences were observed.The bioaccessibility of Cd decreased for D30 and increased for D60 in the colon phase.In addition,the CIPⅠ+Cd(except for D30),CIPⅡ+Cd,CIPⅢ+Cd treatments improved the bioaccessibility of Cd compared with CK+Cd.The CIPⅢ+Cd treatment was the highest for D30 and D60.The sampling time were 20,40,and 60 min for the gastric phase.The results showed that the bioaccessibility of Cd reached maximum at 60 min.Besides,the highest increase in bioaccessibility of Cd among different treatments was at 20 min.In addition,the change in the bioaccessibility of Cd was initially fast and then slowed down at different residence times in the gastric phase.The results indicated that ciprofloxacin had a certain effect on the bioaccessibility of Cd in compound-contaminated soils.