Mountain rivers in densely populated areas have recently been reported as substantially polluted by macroplastics [1]. Previous works suggest that macroplastic delivered to mountain river channel can be quickly fragmented to microplastic, because of distinct natural characteristics of  mountain river channel (e.g. high energy of flow, steep gradient, coarse bed sediments).  The produced microplastic (and  related risks) can not only affect mountain rivers but can also be transported downstream to lowland rivers and oceans [2]. The information on local, regional, and global patterns of plastic emission within mountain river catchments is crucial for planning effective mitigation strategies.

Here we combine existing databases of river catchments [3] and mismanaged plastic waste (MPW) emission [4] to calculate flux of plastic waste from global mountain river catchments [t yr^-1]. Our results demonstrate the highest plastic emissions in Asian mountain river catchments, with the maximum (total MPW 37111630 t yr^-1) detected in Himalayas. Similar values were also observed in mountain river catchments in the Chilean Andes; however, the number of hotspots was lower in this region. Mountain river catchments in Europe (especially northern Europe) and Australia are influenced by three times lower emissions of MPW compared to those in Asia and South America. We identified numerous hotspots of MPW emission in mountain river catchments that coincide with areas of extreme rainfall occurrence (particularly in the Southeast Asia region). This spatial correlation may consequently accelerate microplastic production during extreme events and facilitate its downstream transport. The obtained data provide a unique source of information for future detailed research aimed at mitigating the plastic pollution problem in global mountain rivers and highlight areas that require urgent regulations to address the plastic pollution problem.

The study was completed within the Research Project 2020/39/D/ST10/01935 financed by the National Science Centre of Poland.

References

[1] Liro, M., Mikuś, P., Wyżga, B., 2022. First insight into the macroplastic storage in a mountain river: The role of in-river vegetation cover, wood jams and channel morphology. Sci. Total Environ.838, 156354. https://doi.org/10.1016/j.scitotenv.2022.156354

[2] Liro, M., van Emmerik, T.H.M., Zielonka, A., Gallitelli, L., Mihai, F.C., 2023. The unknown fate of macroplastic in mountain rivers. Sci. Total Environ. 865, 161224. https://doi.org/10.1016/j.scitotenv.2022.161224.

[3] Ouellet, D.C., Lehner, B., Sayre, R., Thieme, M., 2019. A multidisciplinary framework to derive global river reach classifications at high spatial resolution. Environ. Res. Let. 14(2): 024003. https://doi.org/10.1088/1748-9326/aad8e9

[4] Lebreton, L., Andrady, A., 2019. Future scenarios of global plastic waste generation and disposal. Palgrave Commun. 5 (6), 1–11. https://doi.org/10.1057/s41599-018-0212-7

How to cite: Zielonka, A. and Liro, M.: Macroplastic pollution hotspots across global mountain river catchments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20411, https://doi.org/10.5194/egusphere-egu24-20411, 2024.

Plastic waste as a permanent pollutant in the environment is of increasing concern due to its largely unknown long-term effects on biota. The occurrence in rivers, has, compared to research in the oceans, only become the focus of scientific investigations in the last few years. The Austrian Alps in particular are largely unexplored in this respect. Therefore, the Alplast project addresses microplastic transport from the glaciers at the summit over steep mountain torrents to the lowland rivers and aims in conducting a first inventory of the alpine area. Specifically, analyses of microplastic occurrences are being carried out from the Sonnblick glacier via the Rauriser Ache, the Salzach, the Inn and the Danube and are intended to expand the understanding of processes with regard to the behaviour of microplastics in the water cycle from the glacier to the valley. The influence of snowmelt as well as the temporal development, which can be determined from ice cores, are of great interest. In addition, questions regarding the origin and distribution of plastic in flowing waters as well as the possible biological degradation by microorganisms will be clarified.

Since the sampling areas cover entire catchments at different altitudes, different methodologies and devices are used. For the studies on the glaciers, the snow cover as well as ice cores are sampled and analysed. In the rivers a multi-point method is used due to the spatial distribution of plastic particles in the river cross-section. But the net samples at different depths are combined with isokinetic pump sampling in order to detect the widest possible size range. Isokinetically taken pump samples have the great advantage that a weighting process takes place directly during sampling. This means that samples can be taken in different areas (high and low flow velocities) of the cross-section (together with the nets) and then a composite sample can be analysed for the profile. Particle counts, classification and the measurement of concentrations and loads are then used to determine quantities and the most common types of plastics in the alpine environment. The measuring stations were selected in such a way that more and more potential microplastic sources are added in the course of the catchment in order to achieve the best possible process understanding regarding the origin and fate of the plastic waste.

How to cite: Liedermann, M., Pessenlehner, S., Mayerhofer, E., Schöner, W., Ribitsch, D., Gübitz, G., and Gmeiner, P.: Microplastics in the Alpine watercycle – A combination of methods to cover the widest possible size range , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20682, https://doi.org/10.5194/egusphere-egu24-20682, 2024.

Plastic debris of size < 5mm are considered as microplastics and are serious concern in the present world due to its persistent nature and ubiquitousness in every spheres of the environment. Waste Water Treatment Plants (WWTP) are one of the main point sources of microplastic to the environment. The primary objective of this study was to identify and characterize microplastics present in wastewater from the dairy industry and to suggest effective management practices for their efficient removal before the effluent is discharged into the environment. The samples were collected from the influents to the WWTP, Aeration-tank, Clarifier, Final-effluent and sludge. The microplastic extraction were done by digestion (30%-H₂O₂) and density separation (NaCl and NaI) method. Micro-Raman spectroscopy, SEM and SEM-EDS techniques were used for the identification and characterization of microplastics. The findings indicated that the sludge from the WWTP contained a significantly higher particle count (2560 particles/g) compared to the water samples (38 particles/L). Microplastics of different shapes were identified in the study, its abundance is in the following order: fragments>films/sheets>pellets> foam. The size of microplastics ranges from 20µm to 2500 µm and the highest abundance observed in the range between 100-500 µm. Most of the microplastics were transparent (46.87 %), white (31.26%) and blue (15.62%) in color. Seven different varieties of microplastic such as Polyamide, Polyethylene, Poly-vinyl-chloride, Polypropylene, Low-density-polyethylene, Polyurethanes, Nylon were identified. Polyethylene is the predominant microplastic found in all the samples (62.49%) followed by Polypropylene (11.72%) and Poly-vinyl-chloride (9.37%) respectively. Polyurethane (7.81%) and Nylon (3.9%) were found only in sludge samples. SEM images showed cracks, pores (480 nm to 998 nm), fractures on the surface and are prone to breakdown. Some of the microplastics exhibit signs of being colonized by microorganisms or particle-like structures within cracks, signifying the presence of high surface area. It would increase the chance to attach contaminants, resistant microbes and other pollutants to microplastic when discharged/exposed to more complex environment and elevate its toxicity. SEM-EDS analysis shows microplastics association with metals (Mg, Al, Na, Si, Ca, Fe, Pd). The economical and expeditious solution for microplastic removal is to improve, the current treatment process instead of finding a new method. Some recommendations to enhance the removal of microplastics include lengthening the retention time in the sedimentation/skimming processes, altering the materials in the filtration-units, and improving the flocculation/coagulation methods. For example, aluminum-based coagulant is more effective in eliminating microplastic than Fe and polyacrylamide-based coagulant to reduce, comparatively high microplastics content in the influent and aeration-tank. The extraction of microplastic in fat-trap stage using grease and subsequent pyrolysis prevents larger particles to enter the system and helping to curb the elevated concentration of microplastic in sludge. Co-pyrolysis with biomass and hydrothermal reactions can also be adopted. Recommendations for efficient microplastics management practices were also proposed.

How to cite: Vilambukattu Appukuttan Pillai, S. and Udayar Pillai, S.: Identification, characterization and the removal of Microplastic, a persistent neo-contaminant from Dairy Waste Water Treatment Plant (WWTP), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3011, https://doi.org/10.5194/egusphere-egu24-3011, 2024.

Plastic pollution is acknowledged across all environmental compartments, ranging from high mountain ranges to the deepest abyssal plains. It has been identified in the lithosphere (sediment), hydrosphere (water bodies), atmosphere (air), and biosphere (living organisms). In this context of ubiquitous pollution, beaches, and in particular the wrack line, are commonly used as monitoring sites for plastic pollution. There are established monitoring programs to track plastic pollution at different scales along beaches, such as the OSPAR beach litter monitoring program at the North-East Atlantic scale or the French monitoring program for meso- and large microplastics on beaches.

This study aims to build upon the expertise and experience gained from existing monitoring programs to provide a comprehensive approach for understanding the processes of plastic influx, accumulation, and impregnation on beaches. Four types of coasts were selected in Brittany (Erquy, France) to represent various configurations: (i) Accreting sandy beach, (ii) Eroding sandy beach, (iii) Protected cliff (iv) Exposed cliff. The study covers a period from August 2022 to August 2023, where bimonthly statements were conducted, resulting in seven dataset collection points (308 measurements). Each of the four sectors, measuring 100 meters along the wrack line, was studied using eleven 40x40 cm quadrats spaced every 10 meters. The top centimeter of sand was collected using a trowel and filtered through a 1mm mesh sieve. Seawater flotation was employed to separate and recover plastics.

Plastics were then classified into three categories: large microplastic (1-5mm, LMP), mesoplastic (5-25mm) and macroplastics (>25mm). Plastics were counted and weighed within each category. Four indicators were quantified to monitor potential sources of plastic pollution: (i) "Pellet" indicator of chronic or accidental losses along the plastic production chain, (ii) "Port" indicator for port and related recreational activities, (iii) "WWTP" indicator for water network management issues, (iv) "Butt" indicator for activities linked to the improper disposal of cigarette butts.

Results are presented in the form of box plots providing rich information illustrating variability, outliers, and the overall distribution of quadrat measurements. The maximum value by quadrat reaches 706 items/m² of wrack line. The annual survey provides baseline values for different coast types of 106, 39, 39 and 3 items/m² of wrack line for accreting sandy beach, eroding sandy beach, protected cliff, and exposed cliff, respectively. Out of the total 308 measurements, 82 of them have the smallest value possible, which is 0. Principal Component Analysis (PCA) was finally carried out to understand the importance of various environmental factors (e.g., wind, wave, tidal range) on the influx, accumulation, and distribution of plastics along the wrack line.

By combining surveys across different coastal types in a specific region, this work enhances the understanding of the dynamics of plastic pollution, especially to implement effective environmental monitoring strategies.

How to cite: Rohais, S., Lacroix, C., Tallec, K., Paul, M., and André, S.: Plastic pollution monitoring in the wrack line: baseline and seasonality trends along several coastlines from Brittany (Erquy, France), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3999, https://doi.org/10.5194/egusphere-egu24-3999, 2024.

Plastic pollution in the natural environment poses a growing threat to ecosystems and human health, prompting urgent needs for monitoring, prevention and clean-up measures, and new policies. To effectively prioritize resource allocation and mitigation strategies, it is key to identify and define plastic hotspots. UNEP's draft global agreement on plastic pollution mandates prioritizing hotspots, suggesting a potential need for a defined term. Yet, the delineation of hotspots varies considerably across plastic pollution studies, and a definition is often lacking or inconsistent without a clear purpose and boundaries of the term. In this paper, we applied four common hotspot definitions to plastic pollution datasets ranging from urban areas to a global scale. For each scale, hotspots were defined according to 1) values above the average of the dataset, 2) values in the highest interval, 3) outliers, and 4) values exceeding the 90th percentile. Our findings reveal that these hotspot definitions encompass between 0.8% to 93.3% of the total plastic pollution, covering <0.1% to 50.3% of the total locations. Given this wide range of results and the possibility of temporal inconsistency in hotspots, we emphasize the need for fit-for-purpose criteria and a unified approach to defining plastic hotspots. Therefore, we designed a step-wise framework to define hotspots by determining the purpose, units, spatial scale, temporal scale, and threshold values. Incorporating these steps in research and policymaking yields a harmonized definition of hotspots, facilitating the development of effective plastic pollution prevention and reduction measures.

How to cite: Tasseron, P., van Emmerik, T., Vriend, P., Hauk, R., Alberti, F., Mellink, Y., and van der Ploeg, M.: Defining Plastic Pollution Hotspots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5250, https://doi.org/10.5194/egusphere-egu24-5250, 2024.

Beach litter (BL) poses a constant threat to coastal areas and related ecosystems. Standard monitoring techniques used so far for the identification and classification of BL items consist of in situ visual surveys, which are time-consuming and only allow to cover limited coastal stretches. Recently, innovative and multi-disciplinary approaches have attempted to limit these logistic and practical issues. In this context, a growing number of studies are exploiting the use of aero-photogrammetric surveys, coupled with GIS software post-processing tools, for the monitoring of BL-related pollution. To this purpose, Unmanned Aerial Vehicles (UAVs) are often used to acquire images that can be used to evaluate the BL items' density and the relationships between coastal morphodynamic processes and BL distribution along the beach profile. In this study, carried out in the frame of the RETURN Extended Partnership and RiPARTI Project, the results obtained from a monitoring survey carried out along the Torre Guaceto beach (Apulia region, Italy) are shown. In particular, aero-photogrammetric flights were conducted to obtain RGB georeferenced orthomosaics on which manual image screening and morphodynamic analysis were performed to define the recent shoreline evolution and analyze the potential influence of coastal processes in the dispersion and accumulation of BL along the beach profile. The visual screening process was carried out in QGIS software and 382 BL items were identified and categorized. Artificial polymers/plastic (88%) turned out to be the most frequently represented object, followed by glass and textiles (3.4%). Coastal evolution trends were estimated using a specific GIS tool. Results highlighted a general retreat trend of the shoreline, with erosion rates ranging from 1.4 m/yr to 0.18 m/yr. The limit of the fixed vegetation has also been affected by recent retreat processes, up to 3 m. The zone between the embryo dune and the foredune limit, corresponding to the inner section of the investigated beach, gathered the highest density of BL items (1.24 items/m²). This zone is relatively far from marine or aeolic processes along the shoreline so, objects tend to lay for a longer period of time. These can constitute accretion cores for small embryo dunes that, in turn, will tend to increase the risk of burial for BL items. In conclusion, this study highlights that the exploitation of UAV systems facilitates the monitoring of wide coastal sectors and the analysis of beach morphodynamic trends, supporting the identification of hotspot areas for BL accumulation and the definition and planning of tailored clean-up activities.

How to cite: Rizzo, A., Sozio, A., Anfuso, G., La Salandra, M., and Sasso, C.: Analysis of the interactions between coastal morphodynamic processes and Beach Litter distribution. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5672, https://doi.org/10.5194/egusphere-egu24-5672, 2024.

Due to the geology of the Mediterranean coastline zone and insufficient waste management in many nations, the Mediterranean Sea has become overflowed with plastic litter attributed to its dense population and high level of tourism activity. To mitigate the plastic pollution, protect marine life, and preserve the ecological balance a series of novel approaches for monitoring and detection of marine litter in the Mediterranean sea are needed. The primary objective of this study is to demonstrate the feasibility of using AI-driven aerial drones for the detection of plastic hotspots on beaches, followed by the use of a monitoring app for community-led plastic pollution monitoring and cleanup initiatives that were held at Saidia beach in Morocco in November 2023. For that purpose, artificial intelligence was tested to quantify and identify litter on beaches using drones that flew over the beach being monitored. Specifically, the drone's video stream is processed by an algorithm that first segments (in polygons) the objects in the video stream and then through deep learning (DL) each object is identified to categorise it as plastic or general waste. The acquired images are then used to train the DL algorithm in order to constantly improve the recognition performance of plastic and other generic waste types. This technique will allow the observation in detail of the monitoring area before and after the monitoring/clean up event, and thus, it can serve as a method to validate the grade of execution of the activity and analysis of the monitored/cleaned area. The focus on citizen science is essential to connect the public with the technologies that will allow them to collaborate in the collection of methodical data that can complement the existing data for a more detailed analysis.Together with the drones, another approach is the new app that will include the option to collect data for beach monitoring and for beach clean-ups. Created to function in both IOS and Android operating systems, this smart app for collecting marine litter monitoring data features an intuitive user interface and other advanced tools to enable even non-professional users to properly collect scientific data. The app also is designed to be used simultaneously by multiple users, that is, to collect data from multiple devices and referring to a single monitoring event. At the conclusion of the event, all collected data can be easily reviewed and supplemented with other advanced metadata for subsequent analysis and sharing activities, as well as then shared in the European repository of the EMODnet ML. The compilation of data from these techniques, to be tested on different demo sites, together with the results of future replications in other areas and the input of data from citizens and external organisations, will be the next step to facilitate a more holistic approach to tackle the crucial situation the Mediterranean sea is facing nowadays due the uncontroled discharge of plastics in its waters.

Acknowledgements

The authors acknowledge financial support from the European Union’s HORIZON EUROPE innovation program for the project REMEDIES awarded under Grant Agreement No. 101093964.

How to cite: Delgado, J., Barkaoui, A., Petelin, M., Palatinus, A., and Velimirovic, M.: AI-driven aerial drones and monitoring app: New developments to facilitate citizen science initiatives on plastic pollution monitoring and clean-ups on beaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7368, https://doi.org/10.5194/egusphere-egu24-7368, 2024.

Riverine macroplastic pollution (>0.5 cm) is omnipresent and can negatively impact ecosystems and livelihoods. Monitoring data are crucial for understanding the nature and extent of pollution as well as aiding the design of effective intervention strategies. Recent years have marked the development of methods to collect surveillance data, primarily focusing on the monitoring of floating plastics and plastics deposited on riverbanks. Today, these methods need validation. Criteria that are essential in robust monitoring are the accuracy and precision of collected data, and the minimum observable particle size. Addressing these challenges, we have conducted field experiments aimed to review the most widely employed protocols: the RIMMEL protocol for floating macroplastics and the river-OSPAR protocol for macroplastics deposited on riverbanks. We find that the recovery of larger pieces ranges between 80-90% for both methods, with the accuracy decreasing significantly when considering smaller items sizes, item colour, number of observers, and factoring in external variables such as bridge height or riverbank surface type. The precision, however, varied greatly between the different experiments. These results indicate that the limits & usage of data from different protocols are highly context dependent. It further highlights the urgent need to include these uncertainties in their communication and utilization. Our result show the urgency of standardizing the operating protocol to optimize the accuracy and precision for measuring riverine macroplastics, and of the necessity to quantify uncertainty in studies estimating plastic fluxes using the two protocols.

How to cite: Vriend, P., Drok, S., Kamp, N., Collas, F., Vijver, M., and Bosker, T.: Validating monitoring methods for riverine macroplastic pollution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9448, https://doi.org/10.5194/egusphere-egu24-9448, 2024.

Marine caves are mostly formed by dissolution processes in carbonate massifs and may be of karst origin, as the last part of a large terrestrial aquifer, or can originate at the sea level through different processes such as chemical dissolution and mechanical action of sea waves. They are affected by wide spatial and temporal environmental variability and/or extreme values of environmental conditions (light, nutrients, oxygen, pH, hydrodynamic conditions, difficulty of larval dispersion etc.). Despite this seemingly hostile environment, marine caves are biodiversity hotspots and refuge habitats, hosting many crevice-dwelling and deep-water species, but also some obligate cave-dwelling organisms.

Studies on anthropogenic pollution of marine caves, generally believed to be pristine environments, are practically missing. Only recently, the microplastic (MP) pollution in sediments, water, and in some benthic, sediment-dwelling organisms (benthic foraminifera, hard-shelled protozoans) of two Mediterranean marine caves has been recorded. The first one was the Bue Marino cave, a huge karst cave of the Gulf of Orosei (Sardinia, Italy) where microplastic was detected at rather low concentrations of 10-27 items kg^-1 and 18-22 items l^-1, in sediments and water, respectively. Microplastic was also recognised, through Micro Fourier Transform Infrared Spectroscopy (μFTIR), in the shell of the agglutinated foraminifer Eggerelloides advena. Microplastic was also recorded in sediments of the small Argentarola cave (Tuscan coast, Italy) at concentrations of 5.4-11.9 items kg^-1, and in the shell of the agglutinated foraminifer Lagenammina difflugiformis. Polyethylene, the most abundant polymer in sediments of both caves, was the one detected in the foraminiferal shells.

These studies have demonstrated that some foraminiferal species, building their shell by collecting sediment particles, also collect tiny MP fragments of the order of magnitude of a few microns due to a scarce selection ability. Consequently, MPs enter the trophic chain because foraminifera are preyed upon by many marine organisms such as gastropods, scaphopods, fishes, decapods, and polychaetes.

The research carried out in marine caves has demonstrated that MP has reached also these remote and enclosed habitats and that MP deposited in sediments is available to the benthic organism and enters the trophic chain at very low phylogenetic levels. Foraminiferal agglutinated species including MP polymers, even if present at low concentrations, may be considered early indicators of MP pollution. A clear indication to consider MP pollution not only in water but also in sediment, to preserve the ecosystem of marine caves, was a relevant result of this research.

How to cite: Romano, E., Bergamin, L., Di Bella, L., and Provenzani, C.: Microplastic pollution in marine caves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16399, https://doi.org/10.5194/egusphere-egu24-16399, 2024.

Researchers are increasingly utilizing Deep Learning methods for computer vision to identify and quantify floating macroplastic litter. While these methods can provide precise assessments of plastic pollution by automatically processing images and videos, they often rely on the availability of large amount of annotated data for supervised learning (SL). Moreover, the manual labeling work is expensive and time-consuming. This hinders obtaining high model generalization capability, which is essential for the development of robust computer vision systems for structural monitoring.

To overcome this challenge, we propose a two-stage semi-supervised learning (SSL) method for detecting floating macroplastic litter based on the SwAV (Swapping Assignments between multiple Views of the same image) approach. SwAV is a self-supervised learning method that extracts the feature representations of data (such as images with macroplastic litter) without manual annotations. In the first stage of the SSL method, we use SwAV to pre-train a ResNet50 (Residual Neural Network with 50 layers) backbone architecture on more than 100K unlabeled images. In the second stage, we add additional layers to ResNet50 to create a Faster R-CNN (Faster Region-based Convolutional Neural Network) architecture, and fine-tune it for object detection using a limited amount of labeled data (<13K images with 2.6K annotations).

We demonstrate the effectiveness and robustness of our methodology for images collected in canals and waterways of the Netherlands and South East Asia. We conduct a thorough comparison with the conventional SL method using the same Faster R-CNN architecture and ImageNet pre-trained weights. The results suggest that our method improves both in-domain and out-of-domain generalization performances over the SL method. Our findings also demonstrate that feature representations learned by the SwAV pre-training on context-related images outperform those learned from much larger, but unrelated, datasets (e.g., ImageNet).

Based on these results, we suggest stakeholders (e.g., researchers, consultants and governmental organizations) to consider SSL methods to develop more robust systems for targeted long-term floating macroplastics monitoring. Future work should focus on scaling up computations by resorting to much larger (e.g., over 1 million images), yet relatively inexpensive, unlabeled datasets to fully exploit SSL.

How to cite: Jia, T., de Vries, R., Kapelan, Z., and Taormina, R.: Detecting Floating Macroplastic Litter with Semi-Supervised Deep Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9691, https://doi.org/10.5194/egusphere-egu24-9691, 2024.

Rivers are one of the main conduits that deliver plastic from land into the sea, and also act as reservoirs for plastic retention. Yet, our understanding of the extent of river exposure to plastic pollution remains limited. In particular, there has been no comprehensive quantification of the contributions from different river compartments, such as the surface, water column, riverbank and floodplain, to the overall river plastic transport and storage. Here, we provide an initial quantification of these contributions. First, we identified the main relevant transport processes for each river compartment considered. We then estimated the transport and storage terms, by harmonizing available observations on surface, suspended and floodplain plastic. This approach was applied to two river sections in the Netherlands, with a focus on macroplastics (≥ 2.5 cm). Our analysis revealed that for the studied river sections, suspended plastics account for over 96% of items transported within the river channel, while their relative contribution to mass transport was only 30-37% (depending on the river section considered). Surface plastics predominantly consisted of heavier items (mean mass: 7.1 g/#), whereas suspended plastics were dominated by lighter fragments (mean mass: 0.1 g/#). Additionally, the majority (98%) of plastic mass was stored within the floodplains, with the river channel accounting for only 2% of the total storage. Our study developed, and demonstrates, a harmonised approach for quantifying plastic transport and storage across different river compartments, providing a replicable methodology  which will be applicable to many different river environments. Our findings emphasize the importance of adopting a systematic monitoring approach, across the range of river compartments encountered, in order to achieve a coherent and  comprehensive understanding of riverine plastic pollution dynamics.

How to cite: Schreyers, L. J., van Emmerik, T. H. M., Huthoff, F., Collas, F. P. L., Wegman, C., Vriend, P., Boon, A., de Winter, W., Oswald, S. B., Schoor, M. M., Wallerstein, N., van der Ploeg, M., and Uijlenhoet, R.: Quantifying plastic contributions to different components of the river channel and floodplain, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10185, https://doi.org/10.5194/egusphere-egu24-10185, 2024.

Plastic monitoring is a challenging task worldwide. Currently, limited plastic measurements are available along the river in coastal areas or in the ocean. Such data from traditional manual monitoring can contribute to describing plastic transport dynamics within river networks, but not extensively in both spatial and time scales. Consequently, it is crucial to advance long-term monitoring within the river corridor in order to properly quantify and characterize  plastic transport and fates.

Recent advances in optical sensing, using commercially available camera systems (e.g. fixed cameras, drones, smartphones) provide huge opportunities in scene monitoring, which has been already successfully integrated in environment-controlled plastic recycling facilities. In this context, image processing techniques can represent a valuable tool, since their use in natural environments introduces a number of difficulties related to light conditions, shadows, and environmental changes (e.g., riparian and submerged vegetation). Therefore, there is a need to build robust methods able to handle such disturbances balancing detection performance with computational cost. 

Considering all these factors, this work utilizes four river plastic datasets (taken from Indonesia, Italy, The Netherlands, and Vietnam) and explores the possibility of tier-based plastic detection, characterization based on different levels of plastic type (from generalized “plastic” to more specific types e.g., plastic, plastic bag, plastic bottle etc.). These datasets represent very different water systems, e.g. urban water systems, natural rivers, tidal rivers, tropical rivers with diverse levels of lighting conditions, water spectra, camera angle, and image resolutions. Different data combinations and augmentation were explored which were used to train base models of YOLOv7 and YOLOv8 (You Only Look Once family of single detectors). Resulting models were compared in terms of transfer learning performance, labor and computational cost.

This work is part of a PRIN funded project, RiverWatch: a citizen-science approach to river pollution monitoring. Preliminary results show that with constant training parameters (batch=16, epoch=100), YOLOv8 performs better than YOLOv7 in river plastic detection. In fact, even though YOLOv7 provides a higher plastic count, this often includes false positives, with generally lower inference scores than YOLOv8. In addition, simple brightness adjustments appear to have a varying effect in improving detection performance depending on plastic types. 

We presented data augmentation methods and techniques in order to improve algorithm detection performance without complicating its network architecture, also in this way the dataset will remain workable with future algorithms. Future work includes the exploration of adding pre-detection localization layers in the test data to enhance local features prior to detection. 

Keywords: river plastic detection, optical remote sensing, YOLO, tier-based plastic characterization, data augmentation

How to cite: Saddi, K. C., Miglino, D., Isgrò, F., Tasseron, P., Poggi, M., van Emmerik, T. H. M., and Manfreda, S.: Building a Comprehensive Dataset for Training Object Detection Algorithms applied on Plastic Transport Monitoring in Riverine Environments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10583, https://doi.org/10.5194/egusphere-egu24-10583, 2024.

Remote sensing observations from satellites have the great advantage of surveying large areas in a short time. On the other hand, the pixel size of satellite-borne camera on the ground is larger than that of drones or ground-based measurements, making it difficult to classify types of litter based on their detailed shape. Detailed spectral measurements using hyperspectral cameras are expected to be effective in classifying plastics and wood floating on the ocean, or litter accumulated on the beach, from vegetation, sand and stones, but the typical ground resolution of existing satellite-borne hyperspectral cameras is about 30 m. It is not easy to discriminate between types of litter and other objects. We have established imaging technology with a bandwidth (FWHM) of 10-20 nm, 1 nm steps at the centre wavelength and ground resolution of 5-120 m in the 0.4-1.0 micron wavelength range by developing and operating a 50 kg class micro-satellite equipped with a liquid crystal tunable filter (LCTF). In order to capture plastic features, it is necessary to observe even longer wavelength ranges. Currently, by developing a new spectral camera and satellite attitude control technologies, we plan to achieve a bandwidth of less than 10 nm and a ground resolution of about 10 m at 0.4-1.6 um. It is also important to build up a spectral library of spectra for different types of litter and plastics based on ground-based measurements. In this presentation, we report on the development of our micro-satellites and on-board cameras, as well as the methodology and status of the construction of the spectral library.

How to cite: Takahashi, Y., Mohamed, S., and Kako, S.: Debris classification based on detailed spectral observations using micro-satellite, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20324, https://doi.org/10.5194/egusphere-egu24-20324, 2024.

Among other marine environmental problems, the issue of marine litter accumulation in the World Oceans is of increased interest. It is relevant not only in areas with direct intense anthropogenic pressure, but also in remote and presumably pristine areas, such as the Arctic Sea. As the concentration of plastic waste in the marine environment increases, it can have impacts on various components of the marine ecosystem, at sea, on the seafloor, on the coasts and in particular in accumulation areas, while it also can negatively affect human social and economic activities. To reduce the release of plastic debris into the marine environment, litter occurrence and pathways need to be studied in order to identify litter sources, requiring monitoring studies that provide comparable results. Here we present the results of studies of the level of pollution by marine litter floating at sea and flowing with rivers in the Arctic region. Ship-based visual observations at sea were performed in the period 2019-2021 in the White Sea, the Barents Sea, the Kara Sea, the Laptev Sea and the East Siberian Sea. To assess the floating litter input with rivers, regular observations (2 times a month) were carried out by the trained observers on the Northern Dvina and Onega rivers. In all cases a standardized methodology was applied to obtain a unified data and to record the data a Floating Macro Litter mobile application (JRC) was used. The methodology contains a unified list and classification of observed floating sea/riverine litter items, which simplifies the data processing and analysis and allows to compare the data. For the first time a large scale assessment of litter pollution was performed in these remote Arctic regions. The international methodology confirmed the possibility of collecting unified data in the region and at the same time revealed some regional features.

How to cite: Pogojeva, M., Zhdanov, I., Berezina, A., Kotova, E., Mikusheva, M., Kozhevnikov, A., Danilova, E., and Yakushev, E.: Monitoring of floating macro litter in the Arctic seas and rivers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11105, https://doi.org/10.5194/egusphere-egu24-11105, 2024.

As a rising global pollution issue, microplastics have been discovered in every major environment around the world. Marine and coastal ecosystems in particular are often highlighted for the presence and impacts of plastic pollution; however, salt marshes are quickly gaining interest, and concern, as potential traps and long-term sinks for microplastics.

Fundamental sedimentation processes within salt marshes are hypothesised to be ideal for microplastic accumulation, as well as potential abundant physical trapping from vegetation. Salt marshes also provide ideal natural conditions that promote the breakdown and degradation of plastic, thus leading to several different incoming sources of microplastic. With several possible plastic inputs, there is the potential for high microplastic concentration in salt marshes, however when compared to other coastal ecosystems, there are very few studies within this habitat and so plastic levels are largely unknown.

As habitats with important ecosystem services such as biodiversity and carbon storage, it is critical that we improve our understanding of the impacts which microplastics may have upon salt marshes. However, to do this we must first understand what the spread of microplastics in this environment is. This project hopes to measure the amount of microplastics in a natural salt marsh, focussing on their spatial distribution throughout the marsh and neighbouring mudflats. From this initial location data, we will then investigate the impact of physical marsh attributes on any distribution trends and see how much the amount of microplastics across the marsh can be explained by these factors.

How to cite: Grover, B. and Nolte, S.: Studying the Presence and Distribution of Microplastics in a Norfolk Salt Marsh, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3193, https://doi.org/10.5194/egusphere-egu24-3193, 2024.

Geosynthetics are a wide range of materials used in many fields ranging from civil engineering to agriculture, road transport and environmental protection. Made up of synthetic or natural polymers, these materials are characterized by their strip shape of varying width and length. It is estimated that currently 150 million m² of geosynthetics are used in France (data from the French Geosynthetics Committee). Despite this massive and constantly increasing use in recent years, their impact on the environment and in particular in terms of the emission of plastic particles, has been very little studied. It is therefore crucial (1) to quantify the risk of fragmentation and emission of plastic particles by geosynthetics and (2) to investigate how exposure to environmental conditions or implementation methods of these materials are likely to modify the quantities of particles emitted.

In partnership with the Tignes ski slopes authority, the Grande Motte cable car company and the Cimes Conseil design office, a quantification of the fluxes of plastic particles emitted by geosynthetics used for Snow Farming was set up between 2020 and 2023. In a context of climate change, Snow Farming makes it possible to reduce the melting of snow on sensitive parts of the ski area (e.g. ski lifts), during summer periods and thus to optimize the opening periods of the ski stations. The geosynthetics used in this context are exposed to extreme environmental conditions including strong ultraviolet radiation and significant daily temperature variations. These conditions could lead to the fragmentation of plastics and to the subsequent release of microplastics.

The work carried out in this study focused on vertical (through the snow cover) and horizontal (at the surface) particle fluxes. These fluxes were compared to the atmospheric fallout of microplastic at the scale of the glacier on which the ski area is located. In addition, 3 types of geosynthetics were compared: a waterproof PVC tarpaulin, a permeable polypropylene tarpaulin and a tarpaulin made from natural materials. The work showed very contrasting results between the 3 types of tarpaulins.

Permeable polypropylene tarps showed the greatest fluxes of particles (microplastics and mesoplastics) to the snowpack in terms of mass, with transfers exceeding one meter in depth. PVC tarpaulins showed grater fluxes in terms of number of particles and the transfers were limited to snow directly in contact with the tarpaulins. These differences are probably explained by contrasting emissions processes linked either to environmental exposures or to the handling of the tarpaulins. No plastic contamination could be detected in the tarpaulins of natural origin. On the scale of the glacier, the fluxes emitted annually represent approximately 2.3 kg and are of the same order of magnitude as the atmospheric fallout (about 8 kg) while the tarpaulins only cover 0.44% of the glacier surface.

How to cite: Gateuille, D., Naffrechoux, E., Pin, M., and Gillet, F.: Emission of microplastics by geosynthetics during Snow Farming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13346, https://doi.org/10.5194/egusphere-egu24-13346, 2024.

Urban centers worldwide, especially in rapidly developing nations, grapple with significant challenges in solid waste management (SWM). High waste generation, limited finances, and the influx of plastic material into historically plastic-free waste streams resulted in plastic waste accumulation in the environment (or unsustainable open dumping practices). Environmental challenges extend beyond SWM, impacting human life, infrastructure (e.g., waterway, sewage, stormwater network), and diverse ecosystems (e.g., mudflats, beaches, mangroves) crucial for protecting ecological barriers and preserving marine diversity. The ecological and socio-economic concerns spanning from plastic pollution necessitate a nuanced understanding of its abundance and distribution in urban areas to devise effective and targeted interventions. Investigative efforts on plastic pollution accumulation patterns are mainly conducted in industrialized nations, marine settings, and remote locations, creating a knowledge gap that hinders locally influential strategizing. This study assessed geospatial patterns of prominent plastic accumulation sites in Mumbai, India, considering the interplay of geographical and socioeconomic factors. Sampling methods comprised in-situ observations of 249 plastic accumulation sites across the city from April to May 2022, alongside 241 satellite-based remote observations utilizing spectral properties to analyze a broader range of sites. Sites were geospatially analyzed with urban geographical features. Results showed that more than half the sites fall within 100 meters of a residential or commercial building (283) and informal settlement (434), spanning an area of 335,549 and 493,076 m². Concerning the correlation between the proportion of plastic waste to feature-based land area coverage, we found an accumulation of roughly 2.2 m² and 2.0 m² of plastic waste within 100 meters for every 100 m² of waterway and railway. Although significant, the land area to plastic waste area proportion was less for coastlines (0.1m²), intertidal zones (0.3m²), and coastally-located mangroves (0.2m²), supporting evidence that most plastic accumulates inland and is transported to the ocean via waterways and other mechanisms. Notably, most plastic accumulation sites were closer to waterbodies, green spaces, railways, and buildings, with only a few near roads. Accessing these sites often required a park-and-walk approach. This illustrative study underscores the advantages of identifying specific locations and patterns of plastic pollution accumulation as a crucial first step in achieving integrative material management. The visually compelling narrative equips communities with vital information for targeted strategies, emphasizing early intervention’s significance in curbing environmental impacts and protecting livelihoods. Visual representation fosters transparency, enhancing accountability for policy changes. This study urges a focus on addressing plastic pollution at its source, emphasizing proactive mitigation’s practicality and effectiveness. It underscores the importance of decisive action, advocating for early intervention as a vital strategy against plastic pollution. Mumbai has introduced a range of initiatives to reduce plastic pollution, including implementing legislation to limit the production and usage of single-use plastic products. Like many cities worldwide, it is a reminder of the pressing need to address social inequalities and environmental sustainability in rapidly growing urban areas. 

How to cite: Mathis, J., Maniyar, C., Mishra, D., Dubey, B., and Jambeck, J.: Uncovering Geospatial Patterns Emphasize the Urgency of Tackling Plastic Pollution at its Source, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14269, https://doi.org/10.5194/egusphere-egu24-14269, 2024.

In the current discourse of marine science, the issue of anthropogenic plastic pollution poses a growing existential threat to marine ecosystems and their inhabitants. The relentless increase in global plastic production further intensifies this ecological challenge, necessitating the adoption of innovative monitoring approaches for marine debris management. This investigation outlines the effectiveness and precision of remote sensing technologies in documenting and monitoring the distribution of macro plastics in marine and coastal environments. It addresses the intricate difficulties in detecting individual plastics due to their diminutive size and demonstrates how remote sensing can surmount these obstacles by identifying accumulations of plastics, with the assistance of natural oceanographic processes like hydrodynamic fronts and eddies. This study is conducted near the fishing harbor in Tharangambadi, Tamil Nadu, India. Experimental methodologies are employed at depths of approximately ten meters to minimize the impact of bottom reflectance and obtain precise spectral signatures of both water and plastics. Utilizing a Fishing Harbor Jetty as a stable platform for drone operations counters challenges related to drone endurance and operational range. A comprehensive setup, employing High-Density Polyethylene (HDPE) nets, buoyancy aids, and anchoring systems, facilitates the deliberate collection of plastic debris for remote detection.
The research methodology incorporates the aggregation of various distinct polymer categories. The experimental setup features two 30 x 30 meter testbeds where waste plastics are secured to HDPE nets using Ziploc ties. These testbeds are strategically placed to enhance the differentiation between water and plastic reflectance. A designated benchmark site near the operational center ensures accurate georectification of images obtained from Unmanned Aerial Vehicles (UAVs), synchronized with the overpass of Sentinel, Landsat, and Planet Scope satellites. Unlike previous studies that used high-resolution aerial RGB imagery from drones to calculate the percentage of plastic coverage in satellite images, this study employs UAVs equipped with push-broom hyperspectral sensors to capture high-resolution (approximately 3nm) spectral signatures ranging from approximately 400nm to 1000nm of aggregated plastics. This approach confirms the feasibility of using satellites to identify macro plastic conglomerations. Concurrent in-situ measurements of the properties of water and plastics provide essential data on the detection of marine macro plastic contaminants.
A comparative analysis between the radiometric measurements of macro plastics' spectral signatures and the hyperspectral data acquired by the drone was conducted. The results demonstrate a strong correlation, suggesting that drone-based hyperspectral data could effectively replace radiometric measurements in future satellite validation or matchup activities. This research represents a significant stride in the remote monitoring and evaluation of plastic pollution, offering a scalable solution with considerable implications for the conservation of marine ecosystems.

Keywords: Macro Plastics, UAV, Hyperspectral Remote Sensing

How to cite: Shanmugam, V. and Palanisamy, S.: Remote Sensing and In-Situ Monitoring of Macro Plastics in Coastal Waters Using Hyperspectral UAV Imaging: A Comprehensive Study near Tharangambadi, Tamil Nadu, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14490, https://doi.org/10.5194/egusphere-egu24-14490, 2024.

Roads are identified by many researchers as important source of waste emissions into the environment [1][2]. Previous works on this topic have analysed spatial distribution of roadside dumping sites as well as composition and amounts of waste they contain [3][4][5]. Recent work has hypothesized that in the case of populated mountain regions, where roads are preferentially located within relatively flat valley bottoms, roads can be an important source of macrolitter to the fluvial system [6]. In this study, we investigate the scale of this phenomenon in the Kamienica Gorczańska catchment in the Polish Carpathians. During fieldwork conducted in 2023, we determined the amount and composition of macrolitter within 103 plots located along various types of roads in the floodplain area of the studied stream. We have distinguished two types roadside macrolitter emission: dispersed and point one. Within plots representing dispersed emission (74) 1759 macrolitter items were reported, including 845 (48.04%) plastic items. Furthermore glass litter had the largest share in the total weight of the colleted waste (56.3%). Moreover, we found that point sources of macrolitter emission (e.g., illegal dumping sites) are most often located along roads surrounded by forests within a distance of up to 100 m from the nearest buildings. Our results highlight the importance of road systems in delivering household waste to the fluvial systems of mountain rivers, suggesting that roadside areas should be more adequately addressed in future waste management strategies.

Keywords: road system, macroplastic, mountain stream, household waste, waste management, Kamienica Gorczańska stream

The study was completed within the scope of the Research Project 2020/39/D/ST10/01935 financed by the National Science Center of Poland

How to cite: Haska, W., Liro, M., and Gorczyca, E.: Road-related macrolitter input to mountain river: the case of the Kamienica Gorczańska stream in Polish Carpathians, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14992, https://doi.org/10.5194/egusphere-egu24-14992, 2024.

Plastic pollution, and in particular, microplastic pollution, is a global environmental concern particularly in marine ecosystems. The small size of these particles (< 5 mm) means they are prone to ingestion and accumulation by organisms across all trophic levels. Beaches are situated on the transition between the terrestrial and oceanic ecosystems, an important habitat for many species, and have long been known to be sinks of other environmental pollutants. However, until recently their importance as sinks for microplastics and the sources involved were relatively unknown.

This study investigates the extent and likely sources of microplastic pollution on beaches in Arctic and sub-Arctic regions, focusing on Svalbard and Iceland. Sediments on beaches at four sites in Svalbard and eleven in Iceland were sampled for microplastics. Subsequent laboratory analyses for microplastic particle ID, size, type, and polymer (using micro-FTIR) was then carried out to estimate abundance and potential uses of the microplastics identified. Statistical analyses of these results, in conjunction with environmental and geographical data, were conducted to identify patterns and potential sources.

The results revealed significant variability in microplastic quantity, types, and polymers across all locations. Sites with the lowest microplastic concentrations were situated in the most remote areas, while those with the highest concentrations were in proximity to areas with intense human activities or higher population densities. Statistical analyses showed a clear relationship between observed data and the proximity to human activities/inhabitation, with environmental conditions such as wind direction and currents also playing a significant contributory role. These findings suggest that the lower microplastic concentrations found in remote areas are background contamination from ocean delivered from more distant densely inhabited regions (notably Western Europe), with the high contamination hotspots linked to local activities. These findings underscore the heightened impact of local human factors in driving elevated microplastic pollution in beach sediments over oceanic controls in remote yet inhabited Arctic and subarctic locations.

How to cite: Dick, J., Lloyd-Jones, T., Galata, S., Lane, T., Cunningham, E., and Kiriakoulakis, K.: The occurrence and sources of microplastics to Arctic and sub-Arctic beaches: human influence on local microplastic hotspots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17352, https://doi.org/10.5194/egusphere-egu24-17352, 2024.

Microplastics are detected in the environment, particularly in oceanic waters, and have adverse effects on marine ecosystems, biota, climate dynamics, and human health, primarily through the induction of marine pollution. The microplastics are introduced into marine ecosystems either as primary particles through direct discharge or as secondary particles resulting from the weathering of macroplastics. For this, a new laboratory optical-based measurement technique using the static light scattering (SLS) instrument was proposed for the detection and quantification of the microplastics size distribution and to mitigate marine pollution. The SLS instrument relies on the Lorenz-Mie scattering and Fraunhofer diffraction theories and a single monochromatic laser beam is passed through the sample and measures the light scattered intensity in all the scattering angles and with one or many detectors. SLS analysis yields information about microplastic samples, including the volume fraction of each size class bin and the cumulative log-normal distribution of particles. The volume fraction calculation will give the microplastics mean diameter (Dµ) and standard deviation (σ). The microplastics considered in the present study, include polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC). The mean size and standard deviation for PE samples are 3 µm and 2 µm and similarly, the mean size and standard deviation for PP are 3.5 µm and 2 µm. In the case of PS samples, the mean size and standard deviation are 3.5 µm and 2 µm, whereas PVC samples demonstrate a mean size and standard deviation of 3 µm and 2 µm. The findings of the SLS data show the Dµ and σ values are in the range of 3-3.5 µm and 2 µm, respectively, for all the microplastic types. The results of the present study will be helpful for a comprehensive understanding of microplastic behavior, facilitating the development of targeted methodologies for detection using hyperspectral remote sensing data in marine environment.

How to cite: Sandhani, C. G., Shanmugam, P., and Sannasiraj, S. A.: Comprehensive Investigation of Microplastics size distribution in Marine Environment: Detection, Quantification, and Optical Analysis Using Static Light Scattering (SLS), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18753, https://doi.org/10.5194/egusphere-egu24-18753, 2024.