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  • 1
    Publication Date: 2023-02-08
    Description: The dynamics of the particulate organic carbon (POC) pool in the ocean are central to the marine carbon cycle. POC is the link between surface primary production, the deep ocean, and sediments. The rate at which POC is degraded in the dark ocean can impact atmospheric CO2 concentration. Therefore, a central focus of marine organic geochemistry studies is to improve our understanding of POC distribution, composition, and cycling. The last few decades have seen improvements in analytical techniques that have greatly expanded what we can measure, both in terms of organic compound structural diversity and isotopic composition, and complementary molecular omics studies. Here we provide a brief overview of the autochthonous, allochthonous, and anthropogenic components comprising POC in the ocean. In addition, we highlight key needs for future research that will enable us to more effectively connect diverse data sources and link the identity and structural diversity of POC to its sources and transformation processes.
    Type: Article , PeerReviewed
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  • 2
    Publication Date: 2024-02-07
    Description: Understanding residence times of plastic in the ocean is a major knowledge gap in plastic pollution studies. Observations report a large mismatch between plastic load estimates from worldwide production and disposal and actual plastics floating at the sea surface. Surveys of the water column, from the surface to the deep sea, are rare. Most recent work, therefore, addressed the “missing plastic” question using modeling or laboratory approaches proposing biofouling and degradation as the main removal processes in the ocean. Through organic matrices, plastic can affect the biogeochemical and microbial cycling of carbon and nutrients. For the first time, we provide in situ measured vertical fluxes of microplastics deploying drifting sediment traps in the North Atlantic Gyre from 50 m down to 600 m depth, showing that through biogenic polymers plastic can be embedded into rapidly sinking particles also known as marine snow. We furthermore show that the carbon contained in plastic can represent up to 3.8% of the total downward flux of particulate organic carbon. Our results shed light on important pathways regulating the transport of microplastics in marine systems and on potential interactions with the marine carbon cycle, suggesting microplastic removal through the “biological plastic pump”.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 3
    Publication Date: 2024-02-07
    Description: Microplastics (MP) including tire wear particles (TWP) are ubiquitous. However, their mass loads, transport, and vertical behavior in water bodies and overlying air are never studied simultaneously before. Particularly, the sea surface microlayer (SML), a ubiquitous, predominantly organic, and gelatinous film (〈1 mm), is interesting since it may favor MP enrichment. In this study, a remote-controlled research catamaran simultaneously sampled air, SML, and underlying water (ULW) in Swedish fjords of variable anthropogenic impacts (urban, industrial, and rural) to fill these knowledge gaps in the marine-atmospheric MP cycle. Polymer clusters and TWP were identified and quantified with pyrolysis-gas chromatography–mass spectrometry. Air samples contained clusters of polyethylene terephthalate, polycarbonate, and polystyrene (max 50 ng MP m–3). In water samples (max. 10.8 μg MP L–1), mainly TWP and clusters of poly(methyl methacrylate) and polyethylene terephthalate occurred. Here, TWP prevailed in the SML, while the poly(methyl methacrylate) cluster dominated the ULW. However, no general MP enrichment was observed in the SML. Elevated anthropogenic influences in urban and industrial compared to the rural fjord areas were reflected by enhanced MP levels in these areas. Vertical MP movement behavior and distribution were not only linked to polymer characteristics but also to polymer sources and environmental conditions.
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2024-03-25
    Description: Thermal methods are of increased relevance in the field of microplastics (MP) analysis. The presented method improvements emphasize the potential of pyrolysis gas-chromatography mass-spectrometry (Py-GCMS) methods for mass-related MP quantification in environmental samples. A previously established Curie-Point (CP)-pyrolyzer is compared to a micro furnace (MF) pyrolyzer of higher sample capacity. The two Py-GCMS systems are examined in terms of calibration aspects like dynamic range, linearity, process standard deviation and overall sensitivity. Here, MF-PyGCMS provided advantages. Depending on the samples and their residual organic matrix content, the related pyrolysis products may interact with relevant indicator ions of interesting polymers. This can hamper or even impede any calibration and quantification of MP in the given sample. An internal standard mixture added just before the pyrolysis process (ISTD py ) mimics these interactions to a certain extent. Based on selected peak ratios, ISTD py offers a possible quantification option in those cases. The application in selected environmental samples (sea salt, surface water and muddy sediment) after adequate preconcentration illustrates the capability and sensitivity of MF-Py-GCMS for MP-quantification regarding the encountered concentrations (ppt–ppm).
    Type: Article , PeerReviewed
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