Plastic Pollution: Advancing The Science To Better Manage Micro- And Nano-Plastics

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Thursday, April 14, 2022 1:00 pm EST
Organizer: Ruth Marfil-Vega, Shimadzu

Plastic pollution is one of the major environmental issues faced on a global scale. In 2019, the most pessimistic estimates suggested that the mass of microplastics in aquatic habitats will surpass that of the fish by 2050. This prediction dramatically changed with the impact of the COVID-19 pandemic since Use of single-use plastic products and recycling and reusing practices were impacted worldwide. Despite current and emerging efforts to mitigate plastic-based waste, the presence of micro- and nano-plastics in the environment is unavoidable since they can persist for decades. Hence, a thorough understanding of the occurrence, fate and effects of these contaminants is essential for supporting the circular economy of plastics, mitigating environmental concerns and implementing regulations across the globe. This symposium will provide the larger science community at Pittcon the opportunity to learn about the fate of plastic materials used in our daily lives and discover the latest developments in regard to the diverse challenges posed by micro- and nano-plastics – namely their toxicity, risk management, method standardization, sources and aging of materials, among others.

Presentation 1
Analysis of Microplastics in Water: Focus on Sampling, Sample Preparation and Green Analytical Protocols
Damia Barcelo, Catalan Institute for Water Research

The sampling, sample preparation and analysis of microplastics (MPs) pollution in water is identified as one major problem the world is currently facing. Consequently, there is an urgent necessity to establish analytical protocols for MPs in water [1]. MPs are not homogeneously distributed in the water column but depending on MPs characteristics (density, shape, size) and environmental variables (type of water, streams, waves). Three approaches nets, sieves, or pumps are commonly used. Net-based sampling devices with different mesh sizes including bongo nets (>500 μm), manta nets (>300 μm), and plankton nets (>200 and >400 μm) to filtration of grab samples (0.45 μm) established that MP concentrations using net-based methods were ∼3 orders of magnitude less than those obtained by filtration of 1 L grab samples. Mesh size is a critical point that determines the minimum size and the number of MPs detected. Furthermore, synthetic fibers and particles (as nanoplastics) having dimensions <25 μm easily bypass these devices. One point that needs to be emphasized is that there is an absolute lack of standardized method or guidelines to sampling water for MPs. Green Analytical Chemistry examines analytical methods from the point of view of their toxicity to both the environment and humans. [2]- This will be related to the 12 principles of green analytical chemistry. Examples of MPs determination in water of the channels and ponds that conduct residual water in two most important cities of Saudi Arabia, Riyadh and Al-Jubail will be reported.Infrared spectral analysis revealed that most of the selected particles were identified as MPs of polypropylene and polyethylene (48.3%) [3]. References [1] Y. Picó, D. Barceló, ACS Omega, 4, 6709-6719 (2019) [2] Y. Picó, D. Barceló, Current Opinion in Green and Sustainable Chemistry, 31, 100503 (2021) [3] Y. Picó, V. Soursou, A.H. Alfarhan, M.A. El-Sheikh, D. Barceló, Journal of Hazardous Materials, 416, 125747 (2021)

Presentation 2
Plastic Pollution: Advancing The Science To Better Manage Micro- And Nano-Plastics
Harry Allen, U.S. Environmental Protection Agency Region 9
The need for understanding the impacts of plastic waste in our environment is rapidly growing with some government intervention already underway. A major issue with estimating microplastics in the environment is their unique properties and subsequent behavior. Microplastics occur as a heterogenous mixture of particulates and fibers of various polymeric materials with variable sizes and densities. Count-based analytical methods, employing micro-spectroscopy, have become widely adopted by researchers. These yield rich information but are difficult to reproduce in environmental samples as they require rigorous preparation techniques to separate polymers from other materials. Gravimetric, or mass-based, methods, most notably Pyrolysis-GC/MS, enable users to achieve polymer identification and mass quantitation directly from samples with minimal particle separation. The resulting mass-based measurements from Py-GCMS are much more robust and repeatable and are easily adaptable for multiple environmental matrices including water, soils, sediments, and air. Gravimetric analysis provides the added benefit of comparability to estimation of other types of pollutants. This talk will present insights into the development of appropriate microplastic field study planning and the future of microplastic monitoring programs with an emphasis on recent efforts in development of ASTM standards for sample collection, preparation and analysis as well as data interpretation.

Presentation 3
Elucidating the Weathering Degrees and Associated Contaminants of Plastic Nurdles and Along Texas Coasts
Zhanfei Liu, The University of Texas at Austin
One type of plastic debris often found along shorelines is nurdles, the pre-produced plastic pellets used to make final plastic products. The nurdles are often spilled to the environment during the processes of production and transportation. Once in environments, the nurdles undergo slow weathering, mainly photodegradation, and adsorb toxic contaminants due to their hydrophobic characteristics, thus acting as vector that passes the contaminants to marine organisms that often feed on nurdles, such as birds and turtles. In this talk, I will present data about the weathering status of nurdles collected along Texas shorelines using Fourier transform infrared spectroscopy and pyrolysis coupled with gas chromatography mass spectrometry. I will also talk about the concentrations and types of contaminants associated with nurdles, including polycyclic aromatic hydrocarbon, polychlorinated biphenyls,and mercury. Our results showed that the more the nurdles were weathered, the more contaminants they adsorbed, and that the types and concentrations of contaminants on nurdles are dependent on the surrounding environment.

Presentation 4
Pyrolysis Coupled to Gas Chromatography Mass Spectrometry as a Tool for Evaluating the Environmental Plastics Cycle
Kevin Thomas, The University of Queensland
Plastics are now reported in all environmental ‘spheres’ (hydro-, litho-, atmo- and bio-) and increasingly in media that indicates human exposure. We need critical understanding of the mechanisms and drivers from the point of plastics release into terrestrial, atmospheric, and freshwater systems through to environmental and human exposure. Increasingly this is being referred to as the environmental plastics cycle where plastics move and transform between compartments in ways that we have yet to fully understand. Pyrolysis gas chromatography- mass spectrometry (Py-GC/MS) methods increasingly show potential as a technique that can add to our understanding of the environmental plastics cycle. Through this presentation examples of how quantitative and qualitative analysis of plastics by Py-GC/MS can help provide understanding of the environmental plastics cycle. This will include assessment of leakage across point and diffuse (e.g., road dust) sources, plastics in seafood and other common foodstuffs, contemporary and historical biosolids (solids waste from sewage treatment) as well as evaluating sources of analytical uncertainty and how these can potentially be overcome will also be presented.

Presentation 5
Streamlined Monitoring Strategy for Characterizing the Life Cycle of Plastics, From the Macro- to the Micro- Sizes
Ruth Marfil-Vega, Shimadzu
Microplastics’ occurrence is a major contributor to aquatic pollution and threat to marine ecosystems because these contaminants persist in the environment for hundreds of years. Estimates calculated in 2019 suggest that mass of microplastics in aquatic habitat will surpass that of fish by 2050. This prediction has dramatically changed with the impact of the COVID-19 pandemic as the use of single-use plastic products have increased since early 2020. This highlights the need for better understanding of the occurrence, fate and effects of microplastics within the context of the overall life cycle of plastic-based waste. We will present a streamlined analytical monitoring strategy that supports research and standardization efforts for characterizing the life cycle of plastics, from the macro- to the micro- sizes, and their traces components. And we will provide examples of the application of traditional and novel analytical techniques for the analysis of microplastics.

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