Seasonal Variability of Optical Properties in a Highly Turbid Lake (Laguna Chascomús, Argentina)

PEREZ, G.L.; LLAMES, M.E.; LAGOMARSINO, L.; ZAGARESE, H.E.

Photochemistry and Photobiology

Wiley-Blackwell Publishing Inc.

Lugar: Hoboken; Año: 2011 vol. 87 p. 659 - 670

1751-1097

We study the underwater light field seasonality in a turbid lake,Laguna Chascomu´ s (Buenos Aires, Argentina). We report (1)relationships between optical properties (OPs) and opticallyactive substances (OASs); (2) relationships between inherent(IOPs) and apparent (AOPs) optical properties; and (3) theseasonal variability in OASs and OPs. Light absorption wasdominated by the particulate fraction. The contributions ofphytoplankton pigments and unpigmented components weresimilar. The best predictors of total particulate absorption,unpigmented particulate absorption, turbidity and vertical attenuationcoefficient were total suspended solids or their ashcontent. Many OASs and OPs varied seasonally. The concentrationsof OASs were higher during spring and summer,resulting in lower transparency and higher turbidity. However,mass-specific absorption coefficients displayed lower valuesduring spring and summer. Thus, the higher light attenuationobserved during spring and summer resulted from higherconcentrations of relatively less absorptive OASs. Collectively,these results suggest that: (1) light extinction is enhanced duringspring and summer; (2) the enhanced light extinction is due tochanges in the particulate fraction; (3) the enhanced lightextinction is mostly due to an increase in the amount ofparticulate material; and (4) the increase of particulate matteralso enhanced light extinction through increased scattering.