颗粒态新污染物的根际赋存

Rhizosphere occurrence of particulate emerging contaminants

随着工农业的不断发展,农田土壤中颗粒态新污染物(particle emerging contaminants,PECs)的数量持续增加.PECs因其粒径和界面效应发生团聚-解团聚、吸附-解吸、溶解-重塑等迁移转化行为,影响其环境归趋与健康风险.PECs的独特粒径效应,使其不仅对生物体造成化学损伤,还会对生物体产生物理损伤,破坏生物体的细胞膜结构,导致氧化胁迫.此外,PECs还具有缓释特性,通过溶解和生物降解等过程缓慢释放出有害物质,产生长期胁迫.根际作为土壤中物质进入植物的重要门户,也是PECs在农田土壤中发生生物地球化学过程的关键微域.本综述指出,PECs不仅可以直接被根系吸收和吸附,还会刺激低分子量有机酸等根系分泌物的释放,驱动根际微生物和土壤动物的群落组成与功能变化,导致根际效应;根际特殊的理化性质使得PECs的根际环境行为不同于非根际,PECs暴露促进还原态低分子量有机酸类根系分泌物的释放,促进PECs的还原、重塑和颗粒分散;此外,根系分泌物促使根际成为土壤微生物和土壤动物的活动热区,两者活跃的生理行为进一步增加了PECs的根际迁移与转化,增加了PECs的生物有效性和暴露风险.明晰PECs的根际赋存与转化特征,为其环境健康风险评估和原位植物修复提供理论基础.

With the continuous development of industry and agriculture,the prevalence of particle emerging contaminants(PECs)in farmland soil is on the rise.These PECs,owing to their unique particle size and interface effects,exhibit complex behaviors such as agglomeration-deagglomeration,adsorption-desorption,and dissolution-remodeling.These processes significantly affect their environmental fate and associated health risks.Owing to their unique particle size,PECs cause not only chemical damage to organisms through the release of hazardous substances like heavy metals and plastic additives during dissolution and biodegradation but also physical damage by disrupting the cell membrane structures and inducing oxidative stress in organisms.In addition,PECs could release some hazardous substances,such as heavy metals and plastic additives,during dissolution and biodegradation,causing long-term risks to the environment.The rhizosphere,the crucial zone surrounding plant roots,serves as an important gateway for these contaminants,facilitating their entry into plants and playing a key role in their biogeochemical cycling within farmland soil.This review points out that PECs can be directly absorbed and adsorbed by plant roots.Furthermore,they stimulate the release of root exudates,such as low-molecular-weight organic acids,which drive changes in the microbial and animal communities within rhizosphere soils.These interactions lead to unique rhizosphere effects,differing from behaviors observed in non-rhizosphere soils.PEC exposure in rhizosphere soils promotes the release of low-molecular-weight organic acids with reduced properties,enhancing the reduction,remodeling and particle dispersion of PECs.Root exudates create hotspots for soil microorganisms and animals,increasing the migration and transformation of PECs.This activity likely improves the bioavailability and exposure risks of PECs to the environment.To better assess the environmental health risks and develop effective in situ phytoremediation strategies for PECs,it is crucial to further investigate their behavior and transformation in the rhizosphere.This will provide a theoretical foundation for assessing their environmental health risks.