Optimization, performance, and application of a pyrolysis-GC/MS method for the identification of microplastics

Plastics are found to be major debris composing marine litter; microplastics (MP, < 5 mm) are found in all marine compartments. The amount of MPs tends to increase with decreasing size leading to a potential misidentification when only visual identification is performed. These last years, pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) has been used to get information on the composition of polymers with some applications on MP identification. The purpose of this work was to optimize and then validate a Py-GC/MS method, determine limit of detection (LOD) for eight common polymers, and apply this method on environmental MP. Optimization on multiple GC parameters was carried out using polyethylene (PE) and polystyrene (PS) microspheres. The optimized Py-GC/MS method require a pyrolysis temperature of 700 °C, a split ratio of 5 and 300 °C as injector temperature. Performance assessment was accomplished by performing repeatability and intermediate precision tests and calculating limit of detection (LOD) for common polymers. LODs were all below 1 μg. For performance assessment, identification remains accurate despite a decrease in signal over time. A comparison between identifications performed with Raman micro spectroscopy and with Py-GC/MS was assessed. Finally, the optimized method was applied to environmental samples, including plastics isolated from sea water surface, beach sediments, and organisms collected in the marine environment. The present method is complementary to μ-Raman spectroscopy as Py-GC/MS identified pigment containing particles as plastic. Moreover, some fibers and all particles from sediment and sea surface were identified as plastic.

Ludovic Hermabessiere, Charlotte Himber, Béatrice Boricaud, Maria Kazour, Rachid Amara, Anne-Laure Cassone, Michel Laurentie, Ika Paul-Pont, Philippe Soudant, Alexandre Dehaut, Guillaume Duflos, Analytical and Bioanalytical Chemistry, , Volume 410, Issue 25, pp 6663–6676

The article

The Impact of Microplastics on Marine Copepods

Marine atmospheres are exposed to a widespread of anthropogenic pollutants, including radionuclides, nanoparticles, sewage, endocrine disruptors, hydrophobic contaminants and plastic debris. Plastic debris is a wide range contaminant of both freshwater and marine ecosystems, where it can accumulate over time and pose a risk to the health of aquatic organisms (Barnes et al. 2009; Derraik 2002). In the last 60 years, there has been a rapid growing in plastic manufacture, and in 2012 over 288 million tonnes of plastic was produced globally (Plastics Europe 2013) which demonstrates 2.8% development upon the previous year (Plastics Europe 2013). It is held on that 10% of plastics mass produced are likely to end up in the marine environment (Thompson 2006).

P. Raju, S. Gunabal, P. Santhanam, Basic and Applied Zooplankton Biology, pp 429-442, , chapter

The chapter

LIFE and the marine environment – Tackling the blight of marine litter

LIFE (“The Financial Instrument for the Environment and Climate Action”) is a programme launched by the European Commission and coordinated by the Environment and Climate Action Directorates-General. The Commission has delegated the implementation of many components of the LIFE programme to the Executive Agency for Small and Medium-sized Enterprises (EASME).

LIFE projects are practical tools in the fight against marine litter or invasive alien species, among others. They help balance or reduce any negative impacts of fishing and aquaculture, underwater noise, marine contaminants and eutrophication.

European Union, 2018, 76 pages, The report

Tackling the blight of marine litter, Stopping microplastics from clothes washing into the sea (p. 39)

Quality Criteria for the Analysis of Microplastic in Biota Samples: A Critical Review

Data on ingestion of microplastics by marine biota are quintessential for monitoring and risk assessment of microplastics in the environment. Current studies, however, portray a wide spread in results on the occurrence of microplastic ingestion, highlighting a lack of comparability of results, which might be attributed to a lack of standardization of methods. We critically review and evaluate recent microplastic ingestion studies in aquatic biota, propose a quality assessment method for such studies, and apply the assessment method to the reviewed studies. The quality assessment method uses ten criteria: sampling method and strategy, sample size, sample processing and storage, laboratory preparation, clean air conditions, negative controls, positive controls, target component, sample (pre)treatment, and polymer identification. The results of this quality assessment show a dire need for stricter quality assurance in microplastic ingestion studies. On average, studies score 8.0 out of 20 points for “completeness of information” and 0 for “reliability”. Alongside the assessment method, a standardized protocol for detecting microplastic in biota samples incorporating these criteria is provided.

Enya Hermsen, Svenja M. Mintenig, Ellen Besseling, and Albert A. Koelmans, Environ. Sci. Technol., Article ASAP, August 23, 2018

The article

Plastic pollution: Scientists identify two more potential ‘garbage patch’ zones in world’s oceans

Study attempts to locate remaining 99% of plastic unaccounted for by conventional surveys.

An attempt to locate millions of tons of “missing” plastic in the world’s oceans has thrown up two locations that may contain enormous, previously unreported patches of debris.

Plastic has risen to the top of the environmental agenda after scientists sounded the alarm about the potential impact it as having on marine life.

Best estimates suggest 10 million tons of plastic are dumped in the sea every year. (…) (Theindependent, 13/09/2018)

The news

Influence of Nano- and Microplastic Particles on the Transport and Deposition Behaviors of Bacteria in Quartz Sand

Plastic particles are world widely present in natural environment and are highly likely to interact with bacteria (the ubiquitous microbes in natural environment), which might affect the transport and deposition of bacteria in porous media. In this study, the significance of plastic particles from nano-scale to micron-scale (0.02-2 μm) on the transport and deposition behaviors of bacteria (Escherichia coli) in quartz sand was examined under environmentally relevant conditions in both NaCl and CaCl2 solutions at pH 6. The results showed that the presence of different-sized plastic particles did not affect bacterial transport behaviors at low ionic strength (10 mM NaCl and 1 mM CaCl2), whereas, at high ionic strength conditions (50 mM NaCl and 5 mM in CaCl2), plastic particles increased bacterial transport in quartz sand. At low ionic strength conditions, the mobility of both plastic particles and bacteria was high, which might drive to the negligible effects of plastic particles on bacterial transport behaviors. The mechanisms driving to the enhanced cell transport at high ionic strength were different for different-sized plastic particles. Specifically, for 0.02 μm nano-plastic particles, the adsorption of plastic particles onto cell surfaces and the repel effect induced by suspended plastic particles contributed to the increased cell transport. As for 0.2 μm MPs, the suspended plastic particles that induced repelling effect contributed to the increased cell transport. Whereas, for 2 μm MPs, the competition deposition sites by the plastic particles was the contributor to the increased cell transport.

HE LEI, Dan Wu, Haifeng Rong, Meng Li, Meiping Tong, and Hyunjung Kim, Environ. Sci. Technol., Just Accepted Manuscript, September 11, 2018

Field-Based Evidence for Microplastic in Marine Aggregates and Mussels: Implications for Trophic Transfer

Marine aggregates incorporate particles from the environment, including microplastic (MP). The characteristics of MP in aggregates and the role of aggregates in linking MP with marine organisms, however, are poorly understood. To address these issues, we collected aggregates and blue mussels, Mytulis edulis, at Avery Point, CT, and analyzed samples with microspectrometers. Results indicate that over 70% of aggregates sampled harbored MP (1290 ± 1510 particles/m3). Fifteen polymer types were identified, with polypropylene, polyester and synthetic-cellulose accounting for 44.7%, 21.2% and 10.6%, respectively, of the total MP count. Over 90% of MP in aggregates were ≤1000 μm, suggesting that aggregations are a sink for this size fraction. Although size, shape, and chemical type of MP captured by mussels were representative of those found in aggregates, differences in the sizes of MP in pseudofeces, feces and digestive gland/gut were found, suggesting size-dependent particle ingestion. Over 40% of the MP particles were either rejected in pseudofeces or egested in feces. Our results are the first to identify a connection between field-collected marine aggregates and bivalves, and indicate that aggregates may play an important role in removing MP from the ocean surface and facilitating their transfer to marine food webs.

Shiye Zhao, J. Evan Ward, Meghan Danley, and Tracy J. Mincer, Environ. Sci. Technol., Article ASAP, August 29, 2018

The article