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Rivers flowing into the ocean have been identified as one of the largest contributors to the marine plastic pollution budget. However, much uncertainty remains over the spatio-temporal distribution of plastic pollution and the scale of fluxes entering the marine environment from river systems. This work aims to develop and validate a new Earth Observation (EO) approach to quantify the microplastic flux rates from rivers into coastal waters using satellite ocean colour data. The current methods available to quantify and monitor microplastic fluxes are based on localised, time and resource intensive in-situ sampling, laboratory analysis and modelling approaches. Previous EO approaches have focused primarily on floating macroplastic aggregation detection in the open ocean and relatively clear coastal waters. Microplastic concentrations are often not sufficiently high to change the water surface optical reflectance signal.. River mouths present additional challenges because the waters are often highly turbid and optically-complex, making it more difficult to accurately detect water constituent components. In light of these challenges, one possible approach to quantify microplastic discharge from rivers is to use an indirect detection method where optically active substances derived from medium resolution optical satellite imagery, like suspended particulate matter (SPM), are used to estimate microplastic concentrations. This study presents the results from an in situ sampling campaign in the estuary at the mouth of the river Tamar (UK). In situ SPM is correlated to microplastic concentrations (100µm¿D¿2.5cm). This relationship is used to produce microplastic proxy concentration and, with river gauge data, a time-varying microplastic discharge estimate for this river system is calculated. The methodology for the microplastic discharge quantification and preliminary results will be presented, discussing the assumptions it makes and the advantages and limitations of the approach. Also see: https://micro2022.sciencesconf.org/427179/document, In MICRO 2022, Online Atlas Edition: Plastic Pollution from MACRO to nano

This document constitutes Deliverable 3.2 of the MONOCLE project and defines operational protocols for deployment of new sensors and platforms. Most systems described here are designed to collect radiometricdata to characteriseirradiance arriving at and leaving the water surface.These systems are essential to build ground networks to support satellite observation calibration and validation.The systemsdescribed hererange from those delivering low-cost observations, including smartphone extensions and the use of‘prosumer’ drones with added payload, to reference systems incorporating high-end spectrometers to provide stable measurements from diverse platforms.In addition, sensors and methodologies which complement in situ and remote radiometric observations are included, specifically to monitor nutrients, turbidity and transparency in optically and morphologically complex water bodies, at small spatial scales. The aim of this report is to provide a set of protocols for the deployment of the MONOCLE systems to ensure best practices before, during and after data collectionAfter reading theseprotocols, operators will be able to work with the following MONOCLE sensors/platforms in the field to collect reliable data: Peak Design Ltd Hyperspectral Radiometer (HSR): intended for permanent mounting situations, providing reference measurements of hyperspectral Global and Diffuse irradiance in the 350 nm – 1050 nm spectral range Solar-tracking radiometry platform (So-Rad): intended to maintain optimal viewing angles of radiance sensors recording water-leaving reflectance in order to avoid sun glint and platform shading, even from moving platforms (ships and buoys). The system is developed to operate autonomously, with low power consumption, integrating radiance sensors and providing connectivity with the MONOCLE back-end. WISPstation: using two sets of sensors looking NNW and NNE to collect water leaving reflectance data. It providestwo optimal viewing geometry moments during the day and a large time window with acceptable viewing geometries that can be accounted for. Imaging sensors onboard of Remotely Piloted Aircraft Systems (RPAS or drones): for the observation of water-leaving reflectance and to derive water quality parameters including Total Suspended Matter (TSM) and chlorophyll-a (Chl-a) with RGB and multispectral sensors. iSPEX 2: a smartphone add-on that turns the smartphone camera into a spectropolarimeter. A grating projects a spectrum onto the smartphone camera. This spectrum is modulated by a highly chromatic retarder to include dark bands that contain information on the linear polarisation of the incoming light. KdUINO (KdUSTICK and KdUMOD), a Do-It-Yourself moored instrument that measures the diffuse attenuation coefficient (Kd). The purpose is to assess the water transparency, a critical parameter to know the environmental status of water bodies, strongly affected by different water quality related components (such as the presence of phytoplankton, organic matter and sediment concentrations). FreshWater Watch (FWW) is an integrated and flexible citizen science programme run with a specific focus on water quality monitoring. The programme was designed to explore the effects of river restoration, catchment management practices and land use change on the chemical, biological and optical characteristics of freshwater ecosystems, including lakes, ponds, streams, rivers, canals, and wetlands.

This document includes the Mission Statement and the Terms of Reference of the Task Force on Remote Sensing of Marine Litter and Debris of the International Ocean-Colour Coordinating Group (IOCCG). The Task Force has as an overarching goal to coordinate the advancement of current and future remote sensing technologies and techniques that have potential to provide observations of marine plastic litter over all aquatic environments. Considering all remote sensing technologies (with a special focus on radiometric approaches), the Task Force aims to promote a unified interdisciplinary international team of remote sensing experts with the goal to coordinate the development of traceable and transparent approaches for detecting, identifying, quantifying and tracking requirements of plastic litter. These requirements will be supported by four interlinked core topics that are the foundation pillars of the Task Force; (i) technologies, (ii) algorithms and applications, (iii) datasets and (iv) interdisciplinary aspects.

This is the Final Report of the European Space Agency (ESA) project OPTIMAL, funded by the ESA General Studies Programme (GSP), with contract no. 4000120879/17/NL/PS. The OPTIMAL project investigated the feasibility of Remote Sensing of Marine Litter, in particular marine plastic. The Final Report provides a summary of the work carried out in this project, and it includes a brief introduction to the scientific background, development of user requirements and main results from the experimental and modelling phases, scientific impact and assessment, concluding with a forward look and final remarks.

Plastics and other artificial materials pose new risks to the health of the ocean. Anthropogenic debris travels across large distances and is ubiquitous in the water and on shorelines, yet, observations of its sources, composition, pathways, and distributions in the ocean are very sparse and inaccurate. Total amounts of plastics and other man-made debris in the ocean and on the shore, temporal trends in these amounts under exponentially increasing production, as well as degradation processes, vertical fluxes, and time scales are largely unknown. Present ocean circulation models are not able to accurately simulate drift of debris because of its complex hydrodynamics. In this paper we discuss the structure of the future integrated marine debris observing system (IMDOS) that is required to provide long-term monitoring of the state of this anthropogenic pollution and support operational activities to mitigate impacts on the ecosystem and on the safety of maritime activity. The proposed observing system integrates remote sensing and in situ observations. Also, models are used to optimize the design of the system and, in turn, they will be gradually improved using the products of the system. Remote sensing technologies will provide spatially coherent coverage and consistent surveying time series at local to global scale. Optical sensors, including high-resolution imaging, multi- and hyperspectral, fluorescence, and Raman technologies, as well as SAR will be used to measure different types of debris. They will be implemented in a variety of platforms, from hand-held tools to ship-, buoy-, aircraft-, and satellite-based sensors. A network of in situ observations, including reports from volunteers, citizen scientists and ships of opportunity, will be developed to provide data for calibration/validation of remote sensors and to monitor the spread of plastic pollution and other marine debris. IMDOS will interact with other observing systems monitoring physical, chemical, and biological processes in the ocean and on shorelines as well as the state of the ecosystem, maritime activities and safety, drift of sea ice, etc. The synthesized data will support innovative multi-disciplinary research and serve a diverse community of users.

This document constitutes Deliverable 4.1 of the MONOCLE project and provides an overview of the key performance indicators (KPIs) for each sensor or system as defined at the start of the project, briefly summarised as follows. Prosumer units of a Remote Piloted Aircraft System (RPAS), either DJI Phantom 4 pro or DJI M200, equipped with a range of cameras (RBG, Micasense Red-edge or Multispectral) are intended to be deployed by professionals and citizen science groups. These sensors measure radiance of the water surface and convert this to water-leaving reflectance, which will be validated by a TriOS Ramses, ASD Field Spec or WISP system. Concentrations of total suspended matter (TSM) and chlorophyll-a (Chl-a) derived from the camera imagery will be validated against laboratory measurements. Target measurement precision and performance accuracy for all parameters will be tested and are expected to depend on illumination conditions. The HSP1 is a fixed installation that will collect global and diffuse irradiance measurements, to be validated against a sun photometer (e.g. Cimel) in the field. Measurement precision is in the range of 3-5%, while target performance accuracy is 5% uncertainty/offset. The CLAM is presently a bench top flow-through system which measures in situ Chl-a concentrations. Measurements will be validated against accredited laboratory analysis of Chl-a (e.g. High Performance Liquid Chromatography (HPLC)). Measurement range and precision are to be tested and feed back into the development cycle, while target performance accuracy will be 10% uncertainty/offset. The sun tracking radiometer platform is a ship-mounted device for control of the azimuth viewing angle of radiometers with respect to the sun and ship heading. Reference values can be calculated from ship compass and solar position. Measurement precision is 1°, while target performance accuracy is 90° and a ship heading is available. The iSPEX is a smartphone add-on for citizen science measurements of aerosol optical thickness (AOT), which will be adapted for MONOCLE to measure water colour. Measurements of AOT will be validated against groundSPEX, MODIS or AERONET measurements. AOT measurement precision is >5% per individual measurement and 50 measurements, and target performance accuracy is The KdUINO is a profiling device from a surface buoy that measures the light extinction coefficient (Kd). It will be adapted for MONOCLE with a new sensor and hardware, improved accuracy and temperature sensors. Measurements will be validated in the laboratory against TriOS radiometers, and precision and accuracy will be defined during the MONOCLE campaigns to feed back into the development cycle. The WISPStation is a fixed installation which measures remote sensing reflectance (Rrs(l)).Measurements will be validated against other high-end calibrated field spectroradiometers (e.g. TriOS Ramses).Measurement precision is 2%, depending on the ambient light and wave conditions) and target performance accuracy will be determined during the MONOCLE campaigns. FreshWater Watch is an established citizen science method for monitoring of global freshwaters, which includes assessments of water colour, turbidity (Secchi tubes) and colourimetric phosphate measurement using inosine enzymatic reactions. Phosphate measurements will be validated in the laboratory (Skalar SAN++ system autoanalyzer with ammonium molybdate). Measurement precision is 43% (Relative Standard Deviation - to be confirmed) and performance accuracy will be defined during the MONOCLE campaigns. The system KPIs described in this deliverable will inform planning of the forthcoming MONOCLE field campaigns as well as the novel development activities (WP2 & WP3) and innovation activities (WP5, WP6 & WP7).