Detecting Ocean Microplastics with Remote Sensing in the Near-Infrared: A Feasibility Study

Since plastic began entering the oceans in the 1950s, trends have shown that this pollution has been and will continue to increase in the future. The only method to estimate the abundance and distribution of ocean plastic pollution is by computer-generated models using data from in-situ plankton net tows, which are costly, time consuming, and cover a relatively small scale. This project investigates the potential of detecting ocean microplastics with satellite remote sensing based on theoretically elevated near-infrared (NIR) reflectance. Emphasis was placed on the Great Pacific Garbage Patch in the North Pacific Ocean, notorious for its extremely high concentration of plastic debris. Floating plastic from this region was treated with bulk optical properties. We examined the inherent optical properties of water and bulk plastic to derive the apparent optical property, remote sensing reflectance. Overall, the optimal NIR wavelength for strongest plastic reflectance was estimated as ~880 nm. Utilizing the Generalized Inherent Optical Properties model, we calculated the theoretical satellite remote sensing reflectance values at 748 and 869 nm for real, in-situ collected plastic concentrations. Preliminary modeling suggests this methodology might be useful for future ocean plastic investigations. All considerations were based on the capabilities and limitations of the ocean color satellite, MODIS Aqua.