16:15–16:30 | ABSTRACT 1303
OPTICAL SIGNATURES OF DISPERSED OIL AND MICROPLASTICS IN SEAWATER: IMPLICATIONS FOR REMOTE SENSING
Dispersed oil is a common component of seawater in coastal and estuarine environments, particularly near ports, oil extraction sites, shipping routes, and spill-affected areas. Microplastic pollution is likewise pervasive in coastal zones and semi-enclosed basins. Due to their hydrophobic nature, oil droplets and microplastics can interact, and as optically significant constituents, jointly modify seawater optical properties and the upwelling light field. Direct measurement of the inherent optical properties (IOPs) of small oil droplets and microplastics (submicron to tens of micrometers) remains challenging. To address this, we applied a Lorenz–Mie-based model to derive hyperspectral IOPs for various oil types and microplastic dispersions with different particle size distributions. The influence of oil type (crude, lubricant, bio-oil), polymer type (PS, PE, PET, PVC), and size distributions (log-normal and Rosin–Rammler) on spectral features of absorption, scattering, backscattering, attenuation coefficients, and volume scattering functions was analyzed. At 10 ppm, absorption coefficients ranged from 0.009 to 0.048 m–1 for bright, semi-transparent oils, were an order of magnitude higher for opaque crude oils, and up to two orders of magnitude lower for microplastics. Backscattering coefficients varied from 0.02 to 0.11 m–1 for oil dispersions, and from near zero for large microplastics (~tens of micrometers) to ~1 m–1 for submicron particles. The modelled IOPs were implemented in Hydrolight simulations to assess impacts on remote sensing reflectance (Rrs). Results indicate up to a threefold increase in Rrs at 590 nm and broadening of the chlorophyll fluorescence peak near 690 nm, with implications for bio-optical algorithm performance.
Kamila Haule, Gdynia Maritime University, [email protected], https://orcid.org/0000-0002-0254-9385
Włodzimierz Freda, Gdynia Maritime University, [email protected], https://orcid.org/0000-0002-9731-5003
Henryk Toczek, Gdynia Maritime University, [email protected], https://orcid.org/0000-0001-5091-3754
Emilia Baszanowska, Gdynia Maritime University, [email protected], https://orcid.org/0000-0002-3041-3725
Artur Bizewski, Gdynia Maritime University, [email protected]
Mirosław Darecki, Institute of Oceanology of Polish Academy of Sciences, [email protected]
Sławomir Sagan, Institute of Oceanology of Polish Academy of Sciences, [email protected]
