STANDARD OPERATION PROCEDURES (SOPS) FOR MICROPLASTIC (MP) SAMPLING AND ANALYSIS
Creators: name: Stratmann, Cleo N.
name: Dris, Rachid
name: Gasperi, Johnny
name: Molazadeh, Marziye
name: Sefiloglu, F. Öykü
name: Löder, Martin
name: Vollertsen, Jes
name: Leslie, Heather
name: Tassin, Bruno
Publisher: name: Zenodo
Year: 2022
Subjects: Microplastics, Analyses

description: Since the beginning of plastic production, approximately 8.3 billion tonnes of plastic have been produced<br> worldwide, of which 60 % ended up in the environment. Microplastics (MPs) are defined as plastic particles<br> ≤5 mm and pollute aquatic ecosystems worldwide, often entering freshwaters in urban areas. MPs affect the<br> environment by releasing toxic compounds, accumulating pollutants, harming organisms, and accumulating in<br> the (human) food chain. The understanding of MPs in freshwater systems is crucial, and rivers are acknowledged<br> to transport MPs into marine ecosystems.<br> The comparability of different study results for MP assessment in the environment is difficult because studies<br> are carried out using widely different methodologies. Difficulties for standardising or harmonising methodologies<br> for MP sampling, sample processing and analysis are manifold. Various aspects influence the quality and the<br> results of studies, such as: diverse sampling locations, heterogeneous samples, available equipment and<br> scientific question. Those aspects are often interdependent, hampering easy and straight forward<br> standardisations. Hence, an underlying concept of standardisation, namely to agree upon certain ways to<br> proceed and accomplish tasks has not fully been developed for MP assessment in freshwaters. However, there<br> is ample consensus in the scientific (and non-scientific) community for the need to develop standards for MP<br> assessment.<br> Nets/trawls for large volume surface water sampling are popular, and the use of a filter-cascade pump set-up for<br> water column sampling has many advantages. Collecting sediment with plastic-free grabbers or corers are<br> suitable. Appropriate sample processing steps (digestion, density separation), and combination/repetition of<br> procedures depending on the sample content (inorganic/organic matter) are necessary, followed by MP particle<br> size fractionation. To comprehensively analyse MPs (determine shape, size, colour, polymer type), a coherent<br> combination of available, complementary techniques (FTIR, Raman, optical microscopy, Pyr-GC-MS) is essential.<br> Quantification (mass, concentration, MP sizes) is important to better understand MP pollution, hence, the<br> acquired data should be reported meticulously in a transparent way using consistent units. Methods for MP<br> assessment depend on the study design, the characteristics of the targeted MPs, the available equipment and<br> more. Therefore, we advise ensuring to provide all data necessary to comprehend the research results and<br> applying good practices along all procedures. Although it is not possible to always apply the same methods for<br> MP assessment in freshwaters among different projects, the recommendations given in this report allow for<br> better comparability of the research results.<br> The project LimnoPlast (2020-2023) aims to assess the sources, fate and sinks of MP in urban freshwater<br> environments and link social, technical and environmental science. Fifteen Early Stage Researcher (ESR) projects<br> have been designed to investigate the MP contamination in Europe’s freshwater systems and tackles the various<br> knowledge gaps. Three of the projects (ESR 3, 4 and 15) will directly assess MP in the water systems in<br> Aalborg/Aarhus (Denmark), the Greater Paris catchment of the Seine river (France) and the City of Amsterdam<br> catchment (The Netherlands), respectively.<br> In the frame of the LimnoPlast project, we conclude that it is inevitable to agree on certain SOPs, while the<br> individuality of each executing project team is taken into account. This report (Deliverable 2.1) contains a method<br> review for sampling, sample processing and analysing MPs in urban freshwater systems, focusing on sediment<br> and water samples. We discuss different procedures regarding flexibility, suitability and representativeness and<br> draw conclusions for recommendations for harmonized strategies (or SOPs) regarding the objectives of the three<br> LimnoPlast projects.<br> The main questions and aspects that are touched upon in this report are:<br> • What are the different steps needed for reliable quantification and characterization of MP?<br> • Which criteria are essential to choose a suitable method?<br> • Where to sample MP (sampling locations)?<br> • How does the targeted size of MP influence the sampling methods?<br> • What influences the matrix has on the sample processing, and how could this be harmonized? What<br> quality assurance (QA) and quality control (QC) processes should be implemented?<br> • What MP characteristics should be analysed and reported (particle size, shape, type of polymer, mass)?