OPTICAL CHARACTERIZATION OF ESTUARINE AND COASTAL WATERS AROUND THE SITE AERONET-OC BAHÍA BLANCA, SW ATLANTIC

PRATOLONGO, P.; ARENA, MAXIMILIANO; DELGADO, A.L.; LOISEL, H.

Congreso; ASLO Acquatic Science Meeting 2023; 2023

The site Bahía Blanca (AERONET-OC, NASA) was established in 2020 at the mouth of the main channel of the Bahía Blanca Estuary, a coastal system characterized by high suspended loads and turbidity. We present remote sensing reflectance (Rs) spectra obtained with a hand-held spectroradiometer and data from intensive field water sampling including measurements of turbidity (T, FNU), chlorophyll a (Chla, μg l−1), suspended particulate matter (SPM, mg l−1), phytoplankton absorption (aphy) and the total particulate matter absorption (ap). According to the Rs spectra, waters within the channel showed relatively low values in the blue and green part of the visible spectrum, maximum Rs values occurred around 570 nm, and remained high in the red, with no clear fluorescence peak. Estuarine waters presented the highest suspended loads (5.1 to 140.6 mg l-1) and T values (8.4 to 147.7 FNU). Chla ranged 0.83 to 6.08 μg l−1 and values were not correlated with T. In the coastal zone out of the estuary, the Rs spectra displayed a relative strong peak around 570 nm as well as a secondary peak at 687 nm. SPM (5.1 to 50.1 mg l-1) and T (5.6 and 43.7 FNU) diminished. Chla ranged 0.78 to 3.74 μg l−1 and the strong correlation between T, Chla, aphy, and ap suggest that the SPM includes a relative high proportion of detrital material and phytoplankton cells. The AERONET site is in the transition between these contrasting estuarine vs coastal water types, and the relative contribution of organic and inorganic compounds to the suspended material would be mostly related with the prevalence of NW winds.