Laurion, I. University of Innsbruck, isaelle.laurion@uibk.ac.at
Sommaruga, R. University of Innsbruck, ruben.sommaruga@uibk.ac.at
Psenner, R. University of Innsbruck, roland.psenner@uibk.ac.at

 
FACTORS CONTROLLING THE ATTENUATION OF ULTRAVIOLET RADIATION IN ALPINE LAKES WITH PARTICULAR ATTENTION TO PHYTOPLANKTON ABSORBING COMPOUNDS
 
Organisms living in clear mountain lakes are presently experiencing high exposure to solar ultraviolet radiation (UVR) because these systems have low protection provided by chromophoric dissolved organic matter. A series of lakes below and above the tree line was sampled in the tyrolian Alps, extending from 1500 to 2800 meters of altitude. In these mountain lakes, dissolved organic carbon concentration ranged from 0.2 to 1.7 mg liter-1 and chlorophyll a from 0.3 to 8 ug liter-1 at the surface and from 1 to 10 ug liter-1 at the deep chlorophyll maximum. We measured the attenuation coefficients of downwelling UVR (e.g. Kd at 320 nm ranges from 0.2 to 2.1 m-1) and the absorbance spectra and fluorescence of chromophoric dissolved organic matter (Raman and quinine sulfate units and fluorescence index) in an attempt to understand and define the contribution of each water-component to the attenuation of UVR. The contribution of UV-absorbing compounds in the attenuation of UVR was also investigated, and the occurence, concentration and composition of mycosporine-like compounds and carotenoids are related to UV-exposure.
 
Day: Wednesday, Feb. 3
Time: 09:00 - 09:15am
Location: Sweeney Center
 
Code: CS65WE0900S