Detecting and monitoring an unusual highly reflective plume from space in the Río de la Plata (Argentina)

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

Conferencia; ECSA 2017 Where Land Meets Ocean: The Vulnerable Interface; 2017

TheRío de la Plata (RdP) river, located in the eastern coast of South America atapproximately 35 °S, carries high amounts of suspended particulate mattermaking this estuary one of the most turbid in the world with meanconcentrations of suspended particulate matter (SPM) ranging from 100 to 300 gm-3 and measured maximum values around 1,000 g m-3. Thehigh sediment concentration, as well as its distribution, has a great impact onthe different uses and functions of the RdP. The capital cities of Argentina and Uruguay(Buenos Aires and Montevideo)are located in the respective margins of the river, being the main source ofdrinking water of Buenos Aires,as well as the area of ​​discharge of its domestic and industrial effluents.The dredging activity in the river is very intense since access channels thatallow the entry of ships from the Atlantic Oceanto upstream ports need dredging with regularity. Therefore, water qualitycontrol in this highly active and human impacted area is fundamental and theknowledge of its dynamics as well as the particle size composition using remotesensing data is highly desired and of great importance. Frommid-May until the end of October 2016 a conspicuous feature has been detectedin the upper RdP estuary using remote sensing imagery, like Sentinel-2,Landsat-8, VIIRS, and MODIS sensors. This unusual plume had a different colorin the RGB composite appearing brighter and more yellow comparing to the adjacentwaters. In September 25, 2016 a field campaign was performed in the upperestuary and measurements were performed in and outside the plume. Waterreflectance was measured and surface water samples were collected for turbidity,SPM, and particle size distribution (PSD) determinations. In this study oceancolor systems with different spectral and spatial resolutions have been used todetect the highly reflective plume during the May-October 2016 period. Samplescollected inside the striking plume showed different spectral characteristics,smaller median particle size, and turbidity (T) values ten times higher (T~500FNU) than the surrounding waters. The variability of the T:SPM relationshipregarding the particle size was analyzed as well as the capability to detectdifferent particle size using ocean colour satellite data.