Potential Use of Ocean Color Data to Retrieve More Than Particle Concentration in a Highly Reflective Dredging Plume in the Río de la Plata (Argentina)

GOSSN, J.I.; MOREIRA, D.; DOGLIOTTI, A.I.; SIMIONATO, C.G.

Dubrovnik

Conferencia; Ocean Optics XXIV; 2018

The Oceanography Society

The Rio de la Plata (RdP) waterway is an essential link between the Atlantic Ocean and numerous ports in Argentina allowing theexportation of grain and agricultural by-products, major drivers in the Argentine economy, to reach destinations all over the world.Given the shallow nature of the estuary, the navigation channels demand regular dredging. Therefore, water quality control in thishighly active and human impacted area is fundamental and the knowledge of its dynamics as well as the particle size compositionusing remote sensing data is highly desired and of great importance. From mid-May until the end of October 2016 an unusuallyintense dredging plume was detected in the upper RdP estuary using remote sensing imagery. In September 25 2016 a field campaignwas performed in the upper estuary and measurements of water refelectance (ρw), turbidity, total suspended matter, and particlesize distribution (PSD) were performed in and close to the plume. Samples collected inside the plume showed different spectralcharacteristics, smaller median particle size, and turbidity (T) values ten times higher (T~500 FNU) than the surrounding waters. In thisstudy ocean color imagery was used to detect the highly reflective plume in May-October 2016. Existing models to retrieve bbp(λ) fromρw(λ) were tested and bbp*(λ)/ap*(λ) ratio were estimated from saturated water reflectance. Backscattering spectral slope and massspecificinherent optical properties were then related to observed variability in measured PSD in and outside the plume showing theirpotential use in retrieving relevant information besides particle concentration (like size) from ρw(λ).