生态环境学报2025，Vol.34Issue(7)：1042-1052,11.DOI:10.16258/j.cnki.1674-5906.2025.07.005
流速和水流中断对纳米塑料与三氯生共迁移的影响
Effect of Flow Rate and Flow Interruption on the Co-transport of Nanoplastics and Triclosan
摘要
Abstract
Nanoplastics,particularly polystyrene nanoplastics(PSNPs),are widely detected in the environment owing to their extensive use in consumer and industrial products.Their high surface area and hydrophobicity enable them to strongly adsorb organic contaminants,such as triclosan(TCS),a persistent antibacterial agent commonly found in wastewater,soil,and sediments.While nanoplastics are known to enhance contaminant mobility,their co-transport behavior under dynamic hydrodynamic conditions is unknown.Flow rate variations and interruptions are common in natural and engineered systems,affecting nanoplastics-contaminant interactions by altering mobility,deposition,and desorption.While increased flow rates can enhance detachment,flow interruption may promote retention through prolonged contact times and irreversible adsorption.However,the mechanisms governing nanoplastic contaminant transport upon flow resumption,including stepwise release and delayed migration,remain poorly understood.This study systematically investigated the flow rate variations and flow interruption effects on PSNP-TCS co-transport in saturated quartz sand.Column transport experiments were conducted to examine breakthrough and retention behaviors,and a mathematical model was used to quantify attachment,detachment,and adsorption-desorption dynamics.These findings provide mechanistic insights into the hydrodynamic regulation of nanoplastics-contaminant transport,contributing to risk assessment and pollution mitigation strategies for aquatic environment.Quartz sand(0.6 mm mean grain size)was used as the porous medium and pretreated through acid washing,deionization,drying,and calcination at 600℃to remove contaminants.The sand had a porosity of 0.44 and a saturated hydraulic conductivity of 1.44 cm·min-1.PSNPs[(121.9±1.8)nm]were obtained commercially and dispersed in a 0.5 mmol∙L-1 NaCl solution,followed by ultrasonication at 100 W for 5 min to ensure homogeneity.TCS stock solutions(2.5 g∙L-1)were prepared in methanol and diluted to 5 mg∙L-1,maintaining a methanol content below 0.2%(v/v)to minimize solvent effects.Transport experiments were performed in glass columns(10.0 cm length and 2.74 cm inner diameter)packed with quartz sand.The columns were pre-equilibrated with a 0.5 mmol∙L-1 NaCl solution for 12 h.Two experimental conditions were investigated:(1)Flow rate variation:Transport behavior was evaluated at 0.3 mL·min-1 and 1.0 mL·min-1 to assess the shear force effects on breakthrough and retention.(2)Flow interruption:Following the introduction of the PSNP and/or TCS for 1.81 times the pore volume at 0.3 mL·min-1,the flow was interrupted for 2,12,or 24 h before resumption to examine the release dynamics.Effluent samples were analyzed using fluorescence spectrophotometry(PSNP,excitation/emission:488/518 nm)and UV spectrophotometry(TCS,210 nm).Zeta potential measurements were performed to evaluate the variations in the surface charge.A convective-dispersive transport model coupled with a dual-kinetic-site adsorption model was used to quantify the attachment,detachment,and sorption parameters.1)PSNP-TCS co-transport Interactions.The results demonstrate a mutual promotion effect between PSNP and TCS,which significantly alters their transport behaviors in quartz sand.TCS reduced PSNP attachment at both reversible and irreversible sites,while increasing detachment at reversible sites,thereby enhancing PSNP mobility.Moreover,PSNP facilitated TCS transport,as evidenced by a 2.6-fold increase in TCS breakthrough recovery and a 76.2%reduction in TCS adsorption.These findings indicate that PSNP serve as mobile carriers for TCS,reducing its retention in porous media.2)Flow Rate Effects on Transport Behavior.Increasing the flow rate from 0.3 mL·min-1 to 1.0 mL·min-1 significantly enhanced the transport of both PSNP and TCS.The detachment coefficient of PSNP at reversible sites increased,whereas TCS adsorption onto quartz sand decreased to 13.0-18.0%of its original value.These changes suggest that higher flow rates disrupt particle-collector interactions,reducing deposition and enhancing contaminant mobility.3)Flow Interruption and Resuspension Mechanisms.Flow interruption induced significant PSNP and TCS retention,particularly at irreversible sites.The longer the interruption,the greater the retention,as reflected in a 3.9-5.1 fold increase in PSNP maximum attachment capacity and a 1.2-1.7 fold increase in TCS adsorption.Upon flow resumption,hydrodynamic shear and turbulence caused the stepwise release of previously deposited PSNP and TCS,leading to sharp concentration peaks before reaching equilibrium.This finding highlights the potential for delayed contaminant migration in transient flow environments.This study systematically examined the co-transport behavior of PSNP and TCS under variable hydrodynamic conditions,revealing critical mechanistic insights into their migration dynamics.These findings confirm that PSNP and TCS mutually enhance each other's mobility,with PSNP acting as a contaminant carrier and TCS altering PSNP stability.AN increase in flow rate facilitated transport,whereas flow interruption promoted retention,followed by stepwise resuspension upon flow resumption.This study advances the fundamental understanding of nanoplastic contaminant transport,emphasizing the role of hydrodynamic forces in regulating their environmental fate.Future research should explore unsaturated flow conditions,heterogeneous porous media,and periodic hydrodynamic fluctuations to develop a more comprehensive framework for assessing nanoplastics-related environmental risks and informing pollution control strategies.关键词
纳米塑料/三氯生/柱实验/迁移/动力学模型Key words
nanoplastics/triclosan/column experiment/transport/kinetic model分类
资源环境引用本文复制引用
马林婷,魏建兵,张巍巍,孙子程,许佳瑶..流速和水流中断对纳米塑料与三氯生共迁移的影响[J].生态环境学报,2025,34(7):1042-1052,11.基金项目
国家自然科学基金项目(31670412 （）
41771200) （）
辽宁省"兴辽英才计划"项目(XLYC2007127) （XLYC2007127）
辽宁省教育厅基本科研项目(LJKQZ20222367 （）
LJ212411035015) （）
