Defining the BASElines and standards for Microplastics ANalyses in European waters : Final report Project BASEMAN

Abstract

Persistent plastic litter amasses. It fragments over time, both before entering and within the marine environment. Together with micro-sized primary plastic litter from consumer products, this leads to an increasing amount of small plastic particles, so called microplastics (MP). The ubiquitous presence and massive accumulation of MP in marine habitats and the uptake of MP by at least 700 marine species biota is now well recognised by scientists and authorities worldwide. However, the impact of plastic particles on aquatic ecosystems is far from understood. A fundamental issue precluding assessment of the environmental risks arising from MP is the lack of standard operating procedures (SOP) for MP sampling and analysis. Consequently, there is a lack of reliable data on concentrations of MP and the composition of polymers within the marine environment. Comparability of data on MP concentrations is currently hampered by the huge variety of different methods, each generating data of very different quality and resolution. Although MPs are recognised as emerging contaminants in the environment, neither sampling, extraction, purification nor identification or quantification approaches are currently standardised, making the increasing numbers of MP studies hardly -if at allcomparable. The overall goal of the interdisciplinary and international collaborative research project BASEMAN was to overcome these problems through a profound and detailed comparison and evaluation of all approaches from sampling to identification of MP. The collaborative research project BASEMAN combined experienced MP scientists (from different disciplines and countries) in a cutting edge project addressing the JPI Oceans pilot call “Ecological aspects of MP in the marine environment”. BASEMAN was structured in 5 work packages (WPs): Defining baselines for all relevant identification approaches (WP1), Preparation of standardized test samples for inter‐lab comparisons (WP2), Inter‐lab and inter‐method comparisons (WP3), Sampling methodologies for MPs in the marine environment: Standardization, suitability and intercomparison (WP4) and finally a coordination work package Coordination, Integration and Synthesis (WP5). In WP1 the strength and limitations of different analytical techniques with respect to MP identification, quantification (numbers and masses) were successfully investigated covering different Fourier-transform infrared spectroscopy (FTIR) techniques, Raman-microscopy, pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) and py-GC/MS with Orbitrap. Multi-spectroscopic databases for FTIR and Raman microscopy were generated encompassing “pristine” synthetic polymers, weathered synthetic polymers but also representative natural substances present in environmental matrices. For evaluation of the generated data, dedicated software pipelines were developed. A MP reference kit was produced and used for investigations on MP weathering and spiking of different samples in inter-lab comparison in WP2 and WP3. For inte-rlab comparisons, different sample matrices (plankton, sediment and biota) were spiked and provided to the participating BASEMAN partners. Unfortunately, unforeseen problems related to milling, sieving, handling & analyses (size distributions) of the polymer beads and the spiking procedure itself (transfer of the kit to the samples) lead to extreme delays. The inter-lab comparison approach to quantitate the small particle fractions below 100 μm particle size from the named matrices with methods of the current state of the art is considered as failed. However, with considerable further method development (including strict QA/QC criteria), the task is considered feasible. Further, in the scope of WP3 several purification methods were developed and/or optimized for the separation of microplastics from sediments. These included newly developed small-scale sediment separators based on density separation. Different purification methods were successfully investigated of which the use of alkaline digestion, enzymatic digestion, wet oxidation (including Fenton’s reagent) were applied, evaluated and to some extent compared. To reduce contamination risks and allow an easier handling a “purification reactor” was developed. In WP4, sampling methodologies for MP in the marine environment were standardized, evaluated (suitability) and compared. For this task, two joint cruises were conducted (Galway Bay, Ireland and Rias de Vigo, Spain). Both cruises intended to collect environmental samples of benthic sediments and water samples from surface and water column. Samples collected in both cruises were aimed to be processed under the same conditions by the different laboratories involved in order to estimate the associated errors of microplastic counting and identification. Furthermore, marine biota species were suggested that might serve as relevant and appropriate as biomonitoring species with respect to MP in Europe. Three white papers finally were generated: i) Standardization protocols for monitoring microplastics in seawater; ii)Standardization protocols for monitoring microplastics in sediments; and iii) Harmonized protocol for monitoring microplastics in biota (in collaboration with the JPI Oceans project EPHEMARE). In general, BASEMAN provided EU authorities with tools and operational measures that can be applied to describe the abundance and distribution of MP in the environment in existing (e.g. MSFD) or future monitoring requirements.