纤维状海洋微塑料静水沉降实验研究  

Study on Settling Experiment of Fibrous Marine Microplastics in Quiescent Water

作　　者：张金凤[1,2] 唐千姿 陈超 季超群[1] 张庆河 Zhang Jinfeng;Tang Qianzi;Chen Chao;Ji Chaoqun;Zhang Qinghe(State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University,Tianjin 300072,China;Key Laboratory of Earthquake Engineering Simulation and Seismic Resilience of China Earthquake,Administration(Tianjin University),Tianjin 300350,China;College of Harbour and Coastal Engineering,Jimei University,Xiamen 361021,China)

机构地区：[1]天津大学水利工程仿真与安全国家重点实验室,天津300072 [2]中国地震局地震工程综合模拟与城乡抗震韧性重点实验室(天津大学),天津300350 [3]集美大学港口与海岸工程学院,厦门361021

出　　处：《天津大学学报（自然科学与工程技术版）》2023年第8期840-849,共10页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(52271289).

摘　　要：近年来海洋微塑料污染治理受到了学者们的广泛关注.海洋微塑料的种类包括纤维、碎片、薄膜和颗粒,其中纤维状微塑料在水体中含量最高.然而纤维状微塑料的沉降形态和沉降速度目前研究还存在不足,已有的一些半经验沉降速度公式需要更多的实验数据进行验证.对不同密度、直径和长径比的聚酰胺和聚酯纤维状微塑料进行了室内静水沉降实验,利用高精度颗粒沉降观测系统对微塑料颗粒沉降过程进行直接测量,并统计了纤维状微塑料颗粒的沉降速度和沉降形态.实验结果表明,当纤维状微塑料的长径比固定时,微塑料颗粒的无量纲沉降速度随无量纲颗粒等效粒径的增大而增大.根据实验测量值和公式计算值的比较,当纤维状微塑料的长径比L d≤6.0时,Khatmullina-Isachenko公式的计算结果较为准确,各组次平均相对误差小于23.61%;而当长径比L d>6.0时,Waldschläger-Schüttrumpf公式的计算结果较为准确,各组次平均相对误差小于20.18%.此外,实验中85.51%的纤维状微塑料的沉降状态是沿着长轴方向的,纤维状微塑料在下沉过程中有旋转形成最大阻力形态的趋势.实验所采用的纤维状微塑料为理想材料,实际海洋中的微塑料颗粒可能因长期光照老化导致表面粗糙度和比表面积增大,应用公式时应注意这些因素对沉降速度造成的影响.本文为微塑料沉降速度的公式选择提供了参考,并为海洋微塑料治理提供了科学依据.The management of marine microplastics pollution has attracted extensive attention of researchers in recent years.The types of marine microplastics include fibers,fragments,films and particles,among which the fibrous ones are the most abundant in the sea water.However,the settling morphology and settling velocity of fibrous microplastics are still insufficiently studied,and the existing semi-empirical formulas for settling velocity need more measured data to verify.In this paper,indoor settling experiments in quiescent water were carried out on polyamide and polybutylene terephthalate fibrous microplastics with different densities,diameters and length-to-diameter(L/d)ratios.The settling processes of fibrous microplastics were measured directly by a high-precision particle settling observation system,and the corresponding settling velocity and settling morphology were counted.Experimental results indicate that the dimensionless settling velocity of microplastics increases with the increase in their dimensionless equivalent diameter when the L/d ratio is fixed.According to the comparison between measured and calculated values,the Khatmullina-Isachenko formula is more accurate if L/d≤6.0,with an average relative error of each group less than 23.61%.How-ever,the Waldschläger-Schüttrumpf formula is more accurate if L/d>6.0,with an average relative error of each group less than 20.18%.In addition,it is found that 85.51%of fibrous microplastics settled along the long axis direction in experiments,since there was a tendency for the fibrous microplastics to rotate and form the maximum resistance mor-phology during their settling process.The fibrous microplastics used in experiments are ideal materials,while the ac-tual microplastics in the ocean may have increased their surface roughness and specific surface area due to long-term light aging,so the effects of these factors on the settling velocity should be taken into account when applying the for-mulas.The research in this paper provides a reference when selecting fo

关 键 词：海洋微塑料 纤维 静水沉降 沉降速度 沉降形态 

分 类 号：X55[环境科学与工程—环境工程]