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Photodegradation of plastic consumer products is known to accelerate weathering and facilitate the release of chemicals and plastic particles into the aquatic environment. However, these processes are complex. In our presented pilot study, eight plastic consumer products were leached in distilled water under strong ultraviolet (UV) light simulating eight months of Central European climate and compared to their respective dark controls (DCs). The leachates and formed plastic particles were exploratorily characterized using a range of chemical analytical tools to describe degradation and leaching processes. These techniques covered (a) microplastic analysis, showing substantial liberation of plastic particles further increased under UV exposure, (b) non-targeted mass spectrometric characterization of the leachates, revealing several hundreds of chemical features with typically only minor agreement between the UV exposure and the corresponding DCs, (c) target analysis of 71 organic analytes, of which 15 could be detected in at least one sample, and (d) metal(loid) analysis, which revealed substantial release of toxic metal(loid)s further enhanced under UV exposure. A data comparison with the US-EPA’s ToxVal and ToxCast databases showed that the detected metals and organic additives might pose substantial health and environmental concerns, requiring further study and comprehensive impact assessments.

The Great Pacific Garbage Patch, a significant collection of plastic introduced by human activities, provides an ideal environment to study bacterial lifestyles on plastic substrates. We proposed that bacteria colonizing the floating plastic debris would develop strategies to deal with the ultraviolet-exposed substrate, such as the production of antioxidant pigments. We observed a variety of pigmentation in 67 strains that were directly cultivated from plastic pieces sampled from the Garbage Patch. The genomic analysis of four representative strains, each distinct in taxonomy, revealed multiple pathways for carotenoid production. These pathways include those that produce less common carotenoids and a cluster of photosynthetic genes. This cluster appears to originate from a potentially new species of the Rhodobacteraceae family. This represents the first report of an aerobic anoxygenic photoheterotrophic bacterium from plastic biofilms. Spectral analysis showed that the bacteria actively produce carotenoids, such as beta-carotene and beta-cryptoxanthin, and bacteriochlorophyll a. Furthermore, we discovered that the genetic ability to synthesize carotenoids is more common in plastic biofilms than in the surrounding water communities. Our findings suggest that plastic biofilms could be an overlooked source of bacteria-produced carotenoids, including rare forms. It also suggests that photoreactive molecules might play a crucial role in bacterial biofilm communities in surface water.

Rivers are pathways and storage zones for plastic pollution. Land-based plastic waste enters river systems through anthropogenic and hydrometeorological processes, after which they are transported and retained. Only a small fraction (<2%) is assumed to make it into the ocean. Understanding and quantifying river plastic transport are important to optimize prevention and reduction strategies and to evaluate the efficacy of new regulations and interventions. To achieve this, consistent and reliable data are crucial. River plastic pollution monitoring is still an emerging field, especially since river-scale plastic pollution assessments are limited to date. Here, we present an estimate of floating plastic transport and polymer characterization along the Rhine, from Switzerland to the river mouth in Netherlands. We show plastic transport is highly variable along the river, but with a significant increase towards the river mouth. High plastic transport was observed close to urban areas, and confluences with tributaries, suggesting both are likely entry points of plastic pollution. The largest plastic transport was measured in the estuary, which is explained by the tidal dynamics, limiting the transport of plastic into the sea. Our results can be used as a baseline to compare with future assessments. Furthermore, the plastic transport and composition estimates can be directly compared to other rivers that applied the same approach, which may reduce the uncertainty in global river plastic emission simulations. With our study, we aim to contribute to the development of a simple harmonized plastic monitoring approach to quantify plastic pollution at the river basin scale.

Plastik und Mikroplastik werden in praktisch allen Gewässern gefunden, auch an entlegenen Orten. Über Flüsse wird ein maßgeblicher Teil des Plastiks in die Meere transportiert. Es gibt Hinweise, dass Talsperren und Stauhaltungen außer Sedimenten auch Mikroplastik zurückhalten. Gezielte Untersuchungen dazu gibt es aber kaum. Im Rahmen des Projektverbundes MikroPlaTaS wurden drei Gewässer mit Staubereichen in NRW untersucht. In allen wurden mehrere Kunststoffsorten in Form von Mikroplastik nachgewiesen.

Rivers are pathways and storage zones for plastic pollution. Land-based plastic waste enters river systems through anthropogenic and hydrometeorological processes, after which they are transported and retained. Only a small fraction (<2%) is assumed to make it into the ocean. Understanding and quantifying river plastic transport are important to optimize prevention and reduction strategies and to evaluate the efficacy of new regulations and interventions. To achieve this, consistent and reliable data are crucial. River plastic pollution monitoring is still an emerging field, especially since river-scale plastic pollution assessments are limited to date. Here, we present an estimate of floating plastic transport and polymer characterization along the Rhine, from Switzerland to the river mouth in Netherlands. We show plastic transport is highly variable along the river, but with a significant increase towards the river mouth. High plastic transport was observed close to urban areas, and confluences with tributaries, suggesting both are likely entry points of plastic pollution. The largest plastic transport was measured in the estuary, which is explained by the tidal dynamics, limiting the transport of plastic into the sea. Our results can be used as a baseline to compare with future assessments. Furthermore, the plastic transport and composition estimates can be directly compared to other rivers that applied the same approach, which may reduce the uncertainty in global river plastic emission simulations. With our study, we aim to contribute to the development of a simple harmonized plastic monitoring approach to quantify plastic pollution at the river basin scale.

Rivers are pathways and storage zones for plastic pollution. Land-based plastic waste enters river systems through anthropogenic and hydrometeorological processes, after which they are transported and retained. Only a small fraction ((Formula presented.) 2%) is assumed to make it into the ocean. Understanding and quantifying river plastic transport are important to optimize prevention and reduction strategies and to evaluate the efficacy of new regulations and interventions. To achieve this, consistent and reliable data are crucial. River plastic pollution monitoring is still an emerging field, especially since river-scale plastic pollution assessments are limited to date. Here, we present an estimate of floating plastic transport and polymer characterization along the Rhine, from Switzerland to the river mouth in Netherlands. We show plastic transport is highly variable along the river, but with a significant increase towards the river mouth. High plastic transport was observed close to urban areas, and confluences with tributaries, suggesting both are likely entry points of plastic pollution. The largest plastic transport was measured in the estuary, which is explained by the tidal dynamics, limiting the transport of plastic into the sea. Our results can be used as a baseline to compare with future assessments. Furthermore, the plastic transport and composition estimates can be directly compared to other rivers that applied the same approach, which may reduce the uncertainty in global river plastic emission simulations. With our study, we aim to contribute to the development of a simple harmonized plastic monitoring approach to quantify plastic pollution at the river basin scale.

Temperature and dissolved oxygen concentration are critical factors affecting the exchange of solutes between sediment and water; both factors will be affected by warming of lakes and thereby influence water quality. Temperature and oxygen responses of single solute fluxes are well known, however not much is known about interaction of temperature and oxygen in regulating the balance of different fluxes in the benthic environment. We analyzed benthic flux (mobilization and immobilization) data of various solutes (DOC, CH4, NO3--N, NH4+-N, SRP, SO4-, Fe, Mn, and O2) collected from laboratory incubations of 142 sediment cores from 5 different reservoirs incubated under varying in-situ temperature and oxygen conditions. Oxygen was the primary driver of benthic fluxes while temperature and total organic content were secondary. Temperature effects on benthic fluxes were stronger under anoxic conditions which imply that warming will substantially increase the benthic fluxes if the sediment surface becomes anoxic. The varying temperature response of processes underlying the studied fluxes will result in a shift of their relative importance in the benthic environment especially in shallow lakes that are more vulnerable to warming. For example more anoxic conditions will shift the equilibrium between net sulfate reduction and methane release towards the latter. We also predict that physical effects of warming leading to hypolimnetic oxygen depletion i.e. stronger stratification and longer hypolimnetic confinement will increase the benthic mobilization of phosphorus, dissolved organic carbon, and methane into water and immobilization of sulfate by the sediments even in deep lakes.

Plastics in freshwaters are a major problem for socio-ecological systems, calling upon smart policies for its solution. At the same time, there is a lack of relevant monitoring data on plastics in freshwaters to design such policies, specifically in the so-called Global South. This study, therefore, aims to analyze the complex barriers to mo-nitoring plastics in freshwaters in example cases of the Global South, as a starting point for more tailored monitoring, and targeted policies to reduce plastics in the environment. Based on a survey amongst 45 stakeholders in Ghana and Cambodia, we systematically analyze general barriers as well as specific technical, human, financial, and knowledge barriers identified through literature analysis and based on eight expert interviews. Results show that barriers to plastic monitoring are in general rather high, with survey respondents indicating rather high challenges with regard to the indicated barriers in both cases. Further, only slight variations between cases exist, with some barriers being slightly higher in Ghana than in Cambodia. Based on these results we call for both specific capacity development activities and less capacity-intense monitoring goals such as macro plastic monitoring to identify hotspots for policy interventions.

Plastics in rivers and lakes have direct local impact, and may also reach the world's oceans. Monitoring river plastic pollution is therefore key to quantify, understand and reduce plastics in all aquatic ecosystems. The lack of harmonization between ongoing monitoring efforts compromises the direct comparison and combination of available data. The United Nations Environment Programme (UNEP) launched guidelines on freshwater plastic monitoring, to provide a starting point for practitioners and scientists towards harmonized data collection, analysis, and reporting. We developed a five-step workflow to support to design effective plastic monitoring strategies. The workflow was applied to three rivers (Rhine, Mekong and Odaw) across relevant gradients, including geography, hydrology, and plastic pollution levels. We show that despite the simplicity of the selected methods and the limited duration of the data collection, our harmonized approach provides crucial insights in the state of plastic pollution in very different river basins globally.

Environmental monitoring involves the quantification of microscopic cells and particles such as algae, plant cells, pollen, or fungal spores. Traditional methods using conventional microscopy require expert knowledge, are time-intensive and not wellsuited for automated high throughput. Multispectral imaging flow cytometry (MIFC) allows measurement of up to 5000 particles per second from a fluid suspension and can simultaneously capture up to 12 images of every single particle for brightfield and different spectral ranges, with up to 60x magnification. The high throughput of MIFC has high potential for increasing the amount and accuracy of environmental monitoring, such as for plant-pollinator interactions, fossil samples, air, water or food quality that currently rely on manual microscopic methods. Automated recognition of particles and cells is also possible, when MIFC is combined with deep-learning computational techniques. Furthermore, various fluorescence dyes can be used to stain specific parts of the cell to highlight physiological and chemical features including: vitality of pollen or algae, allergen content of individual pollen, surface chemical composition (carbohydrate coating) of cells, DNA- or enzyme-activity staining. Here, we outline the great potential for MIFC in environmental research for a variety of research fields and focal organisms. In addition, we provide best practice recommendations.

Das Themenfeld „Plastik in der Umwelt“ ist vielfältig und umfassend. Wissenschaftliche Arbeiten auf diesem Gebiet sind deshalb hochgradig inter- und transdisziplinär und erfordern die Zusammenarbeit von Fachleuten aus vielen naturwissenschaftlich-technischen und sozioökonomischen Disziplinen. Wo verschiedene Disziplinen zusammenkommen, herrscht auch eine gewisse Uneinheitlichkeit bei der Bezeichnung von Dingen: Begriffe und Definitionen im technischen und regulatorischen Bereich sind sehr eng mit spezifischen Anwendungsgebieten verbunden. Deshalb existieren für einen Begriff zuweilen unterschiedliche Bedeutungsebenen. Die vorliegende Handreichung soll dazu beitragen, zu einem gemeinsamen Verständnis der zahlreichen relevanten Begriffe zu gelangen. Einen Begriff oder eine Definition für alle Fallgestaltungen wird es dabei nicht immer geben können. Um dieses Problem so weit wie möglich einzugrenzen, identifizieren die Autor*innen jeweils zunächst den Geltungsbereich von Begriffen und Definitionen und legen dies denweiteren Ausführungen zugrunde. Dieses Kompendium zielt also darauf ab, relevante Begriffe zu schärfen, um zu einem besseren Verständnis innerhalb der heterogenen Community von Plastik in der Umwelt beizutragen. Darüber hinaus soll die Broschüre dazu beitragen, dass die Kommunikation mit und durch außerwissenschaftliche Akteur*innen zum Themenfeld auf ein begrifflich korrektes Fundament gestellt wird, insbesondere in emotional geführten Debatten. Schließlich sind diese Debatten häufig von großer Relevanz für unsere Zukunft, und es erscheint wichtig, dass die notwendigen politischen, gesellschaftlichen und wirtschaftlichen Entscheidungen auf Basis einer wissens- und sachorientierten Faktenlage getroffen werden können.

Die Verbreitung von Mikroplastik in Flüssen verdeutlicht, dass sich Plastik nicht nur im Meer, sondern auch in Binnengewässern nachweisen lässt. Wichtige und bisher wenig untersuchte Kompartimente des Gewässersystems sind Talsperren und Stauhaltungen, deren Funktion im Projekt MikroPlaTaS untersucht wurde. Da sich Mikroplastik auf dem Gewässergrund ablagern kann, stellen Talsperren und Staubereiche mögliche Senken für Mikroplastik dar. Das Verbundprojekt analysierte zum einen das Verhalten und Vorkommen von Mikroplastik in diesen strömungsberuhigten Fließgewässerbereichen. Besonders interessant war dabei die Frage, warum Mikroplastik gerade dort absinkt. So sollte das Projekt dazu beitragen, diese Gewässerbereiche als Senke für Plastik zu bewerten. In diesem Zusammenhang wurde weiterhin untersucht, wie sich Biofilme auf Plastik bilden und warum sich diese bewachsenen Partikel am Boden ablagern. Dies schloss auch die Bewertung der Nahrungsqualität von Plastik-assoziierten Biofilmen ein. Schließlich wurden auch die Auswirkungen auf verschiedene wirbellose Wasserlebewesen untersucht. Dies diente dazu, ein besseres Verständnis der physikalischen Wechselwirkungen zwischen Mikroplastik, mikrobieller Besiedlung, Meio- und Makrofauna im Plankton und Benthos dieser Gewässer zu erreichen.

Iron flocculants play a major role in the remediation of water bodies, removing particulate pollutants such as microplastics through floc formation. Such flocs are prone to microbial iron reduction while lying on top of anoxic sediments, which possibly leads the release of bound microplastics. In this study, Shewanella oneidensis was employed to simulate the impact of microbial iron reduction on the release of polyethylene spheres from sunken flocs in 120 d batch experiments. Most of the flocs iron (oxyhydr)oxides were reduced (70–90%), but this did not affect their integrity. Only a negligible proportion (0.2–2.7%) of polyethylene spheres was released, while the majority remained bound inside the floc matrix. This study exemplifies that flocs are quite stable, even when experiencing microbial iron reduction under anoxic conditions. Thereby incorporation into such aggregates may display a potential mode of long-term microplastics storage in freshwater sediments.