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Plastic Debris: Remote Sensing and Characterization A. Driedger, H. Dürr, K. Mitchell, J. Flannery, E. Brancazi, P. Van Cappellen Plastic debris is a global problem affecting all surface water bodies and their littoral zones, with far-reaching economic, ecological, public health and aesthetic impacts. Plastic pollution is a global, international and trans-boundary issue. Plastic debris are a potential carrier of pathogens and contaminants, while microplastics, largely invisible to the human eye, can accumulate in the food chain. Plastic litter is found in increasing amounts in the Great Lakes, even in remote areas. Existing estimates of plastic pollution are generally based on limited shipboard or aerial observations of large debris patches, and inferences from beach surveys. Reliable regional and global surveys of the amounts, nature and fate of plastics in large water bodies are largely missing. We have initiated a feasibility study to analyze and evaluate the diagnostic capabilities of remote sensing and in situ spectral methods, for detecting and characterizing the distribution of plastic debris in surface waters and associated littoral zones. Preliminary field trials will focus on the Great Lakes as a testing ground for these new approaches. The Plastic Pollution Problem Sources • Recreational activities • Wind and stormwater runoff • Illegal dumping • Wastewater treatment plants • Fishing industry Environmental Impacts • Wildlife entanglement, ingestion • Spreading of invasive species • Transport of toxic chemicals including PCBs and heavy metals • Accumulation in the food chain Socio-Economic Impacts • Shipping/fishing vessel damage • Reduced/impaired fishing catch • Loss of ecosystem services • Beach/harbour cleaning costs • Reduced tourism activity • Potential health impacts Macroplastics (> 5mm) Traditional Surveying Methods • Net tows, beach cleanups → Manually intensive, time-consuming and costly Remote Sensing and Characterization Data Streams and Micro-Satellites Reflected Infrared Spectroscopy Raman Spectroscopy Great Lakes Marine Debris Network An Internet- and Mobile Phone-Based App Polyethylene Reference Spectra Observed Spectra Hörig, B., Kühn, F., Oschütz, F. and Lehmann, F., 2001. HyMap hyperspectral remote sensing to detect hydrocarbons. International Journal of Remote Sensing, 22(8): 1413-1422. Pichel, W.G., Churnside, J.H., Veenstra, T.S., Foley, D.G., Friedman, K.S., Brainard, R.E., Nicoll, J.B., Zheng, Q., Clemente-Colón, P., 2007. Marine debris collects within the North Pacific Subtropical Convergence Zone. Marine Pollution Bulletin 54, 1207–1211. UNEP, 2001. Marine litter - trash that kills. Near-infrared (NIR): (750 – 1400 nm) Short-wave infrared (SWIR): (1400 – 3000nm) Predictive Mapping of Marine Debris Accumulation AVIRIS Bands Used: R: 1672.0200nm G: 1731.7920nm B: 1791.5560nm (Pichel et al., 2007) Debris Estimated Likelihood Index Goal: Obtain current, wave pattern, surface temperature, and chlorophyll-a concentration data from existing models and satellite imagery to identify areas of downwelling and surface convergence in the Great Lakes (indicative of where debris is more likely to collect) and predict where debris will concentrate on beaches. Rationale: Hydrocarbon-bearing substances, including plastics, have typical absorption maxima around 1730nm and 2310nm (Hörig et al., 2001). “In many regions, as much as 90- 95% of marine debris may be comprised of plastics.” - UNEP “In 2012, net tows conducted in the Great Lakes showed there to be over 600,000 plastic pieces per sq. km in some locations.” - 5 Gyres Features: • Integrates beached debris survey data from multiple organizations • Incorporates data into interactive maps and graphs Designed to raise awareness of the plastic debris problem in the Great Lakes, service researchers and industry stakeholders, and encourage public engagement. Rationale: Raman spectroscopy is able to identify plastic components, similar to infrared absorption (Tsuchida et al., 2009). Findings: SWIR has the ideal spectral range for both remote and in situ identification of plastic debris. Due to significant attenuation in water, Reflected IR sensing technology should focus on plastics detection in surface water and beach environments. References Findings: Raman suffers less from attenuation in water than Reflected IR and holds great promise for the development of sensors for monitoring plastics within the water column. AVIRIS Hyperspectral Imagery; predominately plastic litter is distinguishable from its surroundings. Sunshine Canyon Landfill (California) Google Maps View 31 1L surface water samples were collected from the Grand River, Lake Erie and Lake Ontario. Pixel: 7.1m x 7.1m Microscopic pieces of polyethylene, polypropylene, and polystyrene were found in the samples. Microplastics (0.33mm – 5 mm) Microscopic Plastics (< 0.33mm)
