摘要
以太原市北部山区未利用的自然土壤作为供试土壤,基于土柱淋溶方法研究不同深度土壤对2种浓度磺胺嗨啶(sulfadiazine,SDZ)(2和5 mg·kg-1)的吸附行为、不同时间段SDZ在土柱中的淋溶行为、SDZ的地下水污染指数(GUS)以及SDZ在自然土壤中短期的降解产物和可能的降解途径.结果表明:5 mg·kg-1SDZ(SDZ5)在各个深度土层中的吸附浓度显著高于2 mg·kg-1SDZ(SDZ2),且上层土壤吸附累积的SDZ浓度显著高于下层土壤(P＜0.05).随着淋溶时间的延长,SDZ淋溶速率逐渐变慢,8～10 d后趋于稳定,SDZ5向下淋溶的浓度和速率显著高于SDZ2,SDZ的GUS值为2.99,高于地下水污染指数限值(2.80),其进入地下水的可能性和潜在风险增加.此外,依据SDZ淋溶渗滤液中的16种产物,推测出SDZ在未利用土壤中可能存在5条降解途径.该研究证实了土壤中SDZ的吸附和淋溶行为均具有浓度依赖特性,同时揭示了 SDZ在自然土壤中可能的自降解机理,对于研究、识别SDZ的生态风险具有重要的指导意义.
Abstract
Unused soil from the mountainous area at north of Taiyuan City was used to investigate sulfadiazine(SDZ)ad-sorption.Two SDZ concentrations(2 and 5 mg·kg-1)were used.Adsorption by and leaching from different soil layers af-ter different times were investigated by performing column tests.Migration of leached SDZ was assessed using the groundw-ater pollution index,and possible SDZ degradation products and pathways in natural soil were identified.The results indi-cate that the SDZ adsorption capacity of each soil layer was concentration-dependent and markedly more SDZ was adsorbed and accumulated in the upper than in the lower soil.The SDZ leaching rate gradually decreased over time and stabilized af-ter 8-10 d of leaching.Like the adsorption capacity,the SDZ concentration in the leachate and SDZ leaching rate were markedly higher when the SDZ concentration in soil was 5 mg·kg-1 than when it was 2 mg·kg-1.The SDZ groundwater pollution indices(GUS)at SDZ concentrations in soil was 2.99,which was higher than the groundwater pollution index limit of 2.8,suggesting that with the increasing of SDZ concentration in soil,the chance of risks posed by SDZ entering groundwater was also increased.The leachate contained 16 SDZ degradation products,which allowed five possible SDZ degradation pathways in unused soil to be identified.The study confirms that concentration-dependent SDZ adsorption and leaching occurs in soil and SDZ degradation is identified in natural soil.The results can improve our ability to assess the ecological risks posed by SDZ.
基金项目
国家重点基础研究发展计划课题(2018YFC1801104)
山西省基础研究计划(202303021212199)
维普
万方数据