Remote Sensing of Plastic Marine Litter

Motivation

Marine litter can be defined as any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment [1]. The identification of the origin and pathways that lead to litter entering the marine environment can be very complex, due to the multitude of potential sources, but also as litter can be transported by sea currents and wind across long distances [2].

Marine Litter is a global issue and can be found in all the seas from the equator to the poles, and in freshwater systems, such as rivers and lakes. According to monitoring data, the large majority of marine litter is plastic [3], in particular buoyant polymers as polyethylene (PE) and polypropylene (PP). It has been estimated that between 4.8 and 12.7 million tonnes of plastic entered the ocean from land in 2010 alone [4], and plastic production is constantly increasing. Despite this large input, it is estimated that only about a quarter of a million tonne is floating on the surface of the ocean [5], with most of the plastic likely to be sinking. Plastic marine litter not only dramatically affects marine animals and ecosystems, but it also has economic impacts on coastal communities, tourism and fisheries. The issue is also becoming a concern for human health due to contamination of seafood with plastic particles and associated pollutants, some of which are known to be harmful to humans.

Existing ground-based data collection systems are limited and therefore are not able to answer fundamental questions, for instance related to plastic marine litter concentrations and spatial and temporal dynamics (in particular, plastic items can travel over long distances and accumulate over time in areas very far from their source points). This is due partly to the vastness of the problem, partly to the diversity in types of litter and partly to its general sparseness. A remote monitoring system could, if successful, provide missing data on a large scale, possibly at a global level, and for long time intervals. This would have a drastic impact from a scientific viewpoint, by improving quantification of concentrations and by supporting and validating predictive models of transport and accumulation, allowing to better identify sources, sinks and fluxes, and also in order to contribute to prevention and remediation of the issue, by:

• providing clear data for policy-makers to take measures to prevent plastic litter entering the oceans and by monitoring the effectiveness of these measures;
• pinpointing the major sources of litter (e.g. estuaries of large rivers);
• guiding potential cleaning missions and assess their effectiveness.

Background information and current activities
 

The remote sensing of plastic marine litter is in its infancy, e.g. [6]-[15], and there is no doubt it is a big technological challenge. Due to the huge diversity in type and size (from microplastic, i.e. items smaller than 5 mm to macro- and mega-plastic items, lost fishing nets and large marine litter accumulations) and due to the different ways and areas of accumulation, defining observational requirements for plastic marine litter is complex [12], and only the combination of data from different sensing technologies (and observational platforms) might eventually provide a successful remote detection and monitoring of marine litter [16].

Current studies in ESA provided indications of the possibility to remotely detect accumulations of marine litter containing plastic, by using passive optical spectral sensors, and reported promising results with the MultiSpectral Instrument (MSI) on board of the Sentinel-2 satellites, which is, however, not optimized for detection of marine plastics. There are different remote sensing technologies that can be tested to detect plastic marine litter, and they can be classified in passivetechnologies (e.g. optical spectroradiometry, high spatial resolution imaging, microwave radiometry) and active technologies (e.g. LIDAR and RADAR). 

Expected Ideas

ESA seeks novel and innovative ideas that address the remote sensing of plastic marine litter,namely detection, quantification and tracking of plastic litter in saltwater and freshwater systems, including shores/coasts. Ideas shall include the exploitation of at least a space asset and can address the upstream as well as the downstream segment.

In particular, ESA is looking for ideas in the following domains:

1. Novel applications of existing remote sensing technologies or innovative remote sensing technologies for the detection and/or quantification and/or tracking of plastic marine litter;
2. Novel applications of existing remote sensing data processing techniques/algorithms or innovative approaches to the processing of remote sensing data for the detection and/or quantification and/or tracking of plastic marine litter;
3. Novel and innovative ideas for experimental tests for the characterization of plastic marine litter with remote measurement techniques;
4. Novel and innovative ideas for airborne (e.g. planes and drones) campaigns for validation/calibration of satellite data/sensors for the detection and/or quantification and/or tracking of plastic marine litter;
5. Novel and innovative ideas aiming at identifying remote sensing-based proxies of plastic marine litter concentration;
6. Novel and innovative ideas to improve models simulating the transport dynamics of plastic marine litter, by using remote sensing data;
7. Novel and innovative ideas of potential services based on remote sensing data of plastic marine litter.

Read the general rules of participation

References

1. Global Programme of Action for the Protection of the Marine Environment from Land-based Activities, adopted in Washington DC, 1995.
2. J. M. Veiga, D. Fleet, S. Kinsey, P. Nilsson, T. Vlachogianni, S. Werner, F. Galgani, R.C. Thompson, J. Dagevos, J. Gago, P. Sobral, and R. Cronin, Identifying Sources of Marine Litter, MSFD GES TG Marine Litter Thematic Report 2016, JRC Technical Report; EUR 28309; EUR28309; doi:10.2788/018068.
3. OSPAR-Commission (2010a), Quality Status Report 2010, OSPAR Commission, London, 176 pp.
4. J. R. Jambeck et al., Plastic waste inputs from land into the ocean, Science, 2015, 347(6223), 768–771.
5. M. Eriksen, L. Lebreton, H. S. Carson, M. Thiel, C. J. Moore, J. C. Borrero, et al., Plastic Pollution in the World’s Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea, PLOS ONE. 2014; 9(12): e111913.
6. N. Maximenko et al., Remote sensing of marine debris to study dynamics, balances and trends, NASA Workshop on Mission Concepts for Marine Debris Sensing, 2016, University of Hawaii at Manoa, Hawaii.
7. S. P. Garaba, H. M. Dierssen, An airborne remote sensing case study of synthetic hydrocarbon detection using short wave infrared absorption features identified from marine-harvested macro- and microplastics, Remote Sens. Environ. 2018, 205, 224−235.
8. S. P. Garaba, J. Aitken, B. Slat, H. M. Dierssen, L. Lebreton, O. Zielinski, J. Reisser, Sensing Ocean Plastics with an Airborne Hyperspectral Shortwave Infrared Imager, Environ. Sci. Technol. 2018, 52, 20, 11699-11707.
9. L. Goddijn-Murphy, S. Peters, E. van Sebille, N. A. James, S. Gibb, Concept for a hyperspectral remote sensing algorithm for floating marine macro plastics, Mar. Pollut. Bull. 2018, 126, 255−262.
10. T. Acuña-Ruza et al., Anthropogenic marine debris over beaches: Spectral characterization for remote sensing applications, Remote Sensing of Environment 217 (2018) 309–322.
11. K. Topouzelis, A. Papakonstantinou, S. P. Garaba, Detection of floating plastics from satellite and unmanned aerial systems (Plastic Litter Project 2018), Int. Journal of Applied Earth Observation and Geoinformation, Vol. 79, July 2019, pag 175-183.
12. V. Martinez-Vicente et al., Towards marine plastic debris detection from satellite remote sensing: translating observation needs into specifications, in publication.
13. A. Mata et al., Optical Remote Sensing Detection of Plastic Targets on the Shore: Field Campaign and Modelling Results, in publication.
14. L. Biermann et al., Using high resolution data from Sentinel-2 to detect floating debris in coastal environments, in publication.
15. V. Martinez-Vicente et al. Concentration threshold for microplastic detection using remote sensing of ocean colour, in publication.
16. N. Maximenko et al., Towards the Integrated Marine Debris Observing System, in publ. in Frontiers of Marine Science – Ocean Observation.