摘要
微塑料一般是指粒径小于5 mm的塑料颗粒,具有稳定性高、粒径小及迁移性强等特性,能长期存在于土壤环境中,并且充当各种污染物迁移的载体,甚至通过植物富集等方式经食物链逐级传递,对环境和人体健康造成严重危害。然而,由于土壤基质的复杂性和分析技术的限制,关于土壤微塑料的研究尚存很多空白。开展土壤微塑料分析技术的研究是探索微塑料在土壤中的迁移转化规律和评估微塑料生态风险的基础。本文综述了国内外环境样品中微塑料的分离提取和识别定量技术的研究进展,探讨了各方法的优缺点及其对土壤样品的适用性,并对未来分析技术的发展方向提出展望。文章认为,密度分离法作为最常用的分离方法,操作简单且分离效果良好,但存在无法有效去除有机物和分离小塑料颗粒(<50μm)的问题;新兴的加压流体萃取技术会对微塑料结构造成一定破坏,但由于其自动化程度高、成本低、效率高,仍具有良好的应用前景;其他替代方法(如油提法、磁性分离法等)的应用相对有限,其对土壤样品的适用性还有待研究。不同强度的消解方法均会对微塑料结构造成不同程度的破坏,且增强有机质消解效率往往以牺牲微塑料回收率为代价。现阶段的识别定量方法主要包括借助显微镜的目视鉴定方法、以红外光谱和拉曼光谱及其衍生技术为主的光谱分析方法以及与质谱或色谱等联用的热分析方法,这些方法在应用于土壤微塑料识别时存在耗时长、微塑料尺寸和样品量大小受限或破坏微塑料结构等诸多问题,将不同的方法进行组合有望解决这些不足。此外,由于研究者采用的分离检测方法的差异性,研究结果难以横向比较。考虑到现有分离检测方法的局限性,今后的研究重点应在于:(1)建立一套适合土壤中微塑料分离提取和识别定量的标准方法;(2)探索适合小颗粒微塑料的分析手段;(3)开发不损害微塑料结构的高效分离/识别/定量方法。
Microplastics(MPs)refer to plastic debris with a dimension<5 mm and possess high chemical stability,small particle size,and strong mobility.Once they enter the soil environment,MPs can exhibit long-term retention,act as a vector for soil contaminants,and even pass through the food chain by plant enrichment,causing serious damage to the environment and human health.Due to the complexity of soil substrates and the limitations of analytical techniques,there is still a big gap in the study of soil MPs.Research on soil MPs analysis technology is the basis for uncovering the migration and transformation mechanism in soils and to evaluate the ecological risks of MPs.In this study,worldwide research progress on the separation,extraction,and identification of MPs in environmental samples is reviewed.Moreover,the advantages and disadvantages of these methods and their applicability to soil samples are discussed.Finally,the development direction of future research on the analysis technology is suggested.The most common separation method,density separation,is simple and effective for extracting MPs,but it cannot remove organic matter or separate plastic debris<50μm.Though it may damage MPs structures,the newly developed pressure fluid extraction(PFE)still has good application prospects because of its low cost,high automation and efficiency.Other alternative methods(e.g.,oil extraction and magnetic separation)are rarely used,and their applicability to soil samples remains unclear.Also,digestion methods with different intensity are reported to cause different degrees of damage to the MPs structures,and the enhancement of organic matter digestion efficiency is usually at the cost of MPs recovery.The existing identification and quantification methods include(i)visual identification methods with the aid of a microscope,(ii)FTIR and Raman based spectral analysis methods,and(iii)the MS or chromatography coupled thermal analysis methods.When applied to soil MPs identification,these methods exhibited shortcomings such as time consumption,size and amount limitations of MPs sample,and damage to MPs structures.The combination of different technologies is expected to address these shortcomings.Importantly,due to the selection biases of researchers on available separation and analysis methods,the results of different studies were difficult to be compared horizontally.Considering the existing deficiencies in current analytical methods,the future research focus should be(1)to establish standard methods for soil MPs extraction,identification,and quantification;(2)to explore suitable analytical methods for small MPs(<50μm);(3)to develop separation/identification/quantification methods that do not damage MPs structures and are less time-consuming.
作者
陈雅兰
孙可
韩兰芳
高博
CHEN Yalan;SUN Ke;HAN Lanfang;GAO Bo(State Key Laboratory of Water Environment Simulation,School of Environment,Beijing Normal University,Beijing 100875,China;Institute of Environmental and Ecological Engineering,Guangdong University of Technology,Guangzhou 510006,China;State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research,Beijing 100038,China)
出处
《土壤学报》
CAS
CSCD
北大核心
2022年第2期364-380,共17页
Acta Pedologica Sinica
基金
国家自然科学基金面上项目(41977299)
流域水循环模拟与调控国家重点实验室自主研究课题(SKL2020ZY02)资助。
关键词
土壤
微塑料
分离
识别
定量
Soil
Microplastics
Separation
Identification
Quantification
