# Aerial Remote Sensing of Aquatic Microplastic Pollution:
## 4 Discussion and Recommendations
Most are lighter than water, including environmentally pervasive polyethylene, polypropylene, and some polystyrene, all of which tend to float, whereas polyester polyamide and acrylics tend to be submerged. However, for all plastic particles, their mass can increase with time spent in aquatic environments as they weather and accrue materials, causing them to sink in the water column and eventually collect in the sediment [43]. Remote sensing of surface and near-surface MPs could contribute to a fuller understanding of whether surface plastics can be an indicator of recent environmental inputs and/or a source of MPs at greater depths. Further aspects that could be explored include the relationship between MP concentrations near the surface where they are optically detectable and concentrations at greater depths, and how vertical water circulation patterns may affect this relationship. Additional unknowns related to aerial optical remote sensing of aquatic MPs that may warrant investigation include how water surface perturbations such as ripples, waves, or white caps, as well as turbidity in freshwater, estuarine, or coastal systems, affect MP detectability; and whether it is possible to distinguish among different plastic types based on moderate variations in their spectral signatures. In conclusion, despite the relatively sparse published literature and gradual progress to date, there have been promising developments toward aerial remote sensing of aquatic microplastics, and there are clear opportunities to continue moving the science forward, in particular with regard to detecting their spectral characteristics and their effects on water surface roughness. Although the feat is distinctly and inherently challenging, ongoing research efforts, in conjunction with continuously improving remote sensing technology (e.g., sensor resolution/precision and data analysis approaches), seem poised to advance the practice from its current experimental stage to operational status. [PERSON] contributed remote sensing expertise, [PERSON] contributed environmental contaminants expertise, [PERSON] conceived the project, [PERSON] conducted the literature survey and synthesis, [PERSON] was the primary author of the manuscript, and [PERSON] was the secondary author. All authors have read and agreed to the published version of the manuscript. Funding for this work was provided by the Department of Fisheries and Oceans Canada. We thank [PERSON], [PERSON], and [PERSON] for their critical input throughout the literature survey, synthesis, and write-up. The authors declare no conflicts of interest. * [PERSON] et al. (2024) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Evaluating Microplastic Pollution Along the Dubai Coast: An Empirical Model Combining On-Site Sampling and Sentinel-2 Remote Sensing Data. _J. Sustain. Dev. Energy Water Environ. Syst._**2024**, _12_, 1110482. [CrossRef]
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