Spectral Modeling of UV Inhibition of In Situ Antarctic Primary Production Using A Field‐Derived Biological Weighting Function

• Published in: Photochemistry and Photobiology
• Main Authors: Boucher, Nicolas P., Prézelin, Barbara B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1996
• Subjects: Physical and Theoretical Chemistry; General Medicine; Biochemistry; Antarctic; Palmer Station; Palmer-Station; Southern Ocean; Antarc*
• Online Access: http://dx.doi.org/10.1111/j.1751-1097.1996.tb03085.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1751-1097.1996.tb03085.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1751-1097.1996.tb03085.x

Abstract— Our major aim is to illustrate an approach for hindcasting or forecasting UV radiation (UVR, 280–400 nm) effects on in situ rates of aquatic primary production when field measurements do not include estimates of UVR effects. A composite of spectral field measurements is employed to model UVR‐dependent rates of photosynthesis in diatomdominated waters in a coastal region of the Southern Ocean. Assumptions, caveats and limitations of the modeling are discussed. Calculations begin with the 1991 Palmer Long Term Ecological Research (LTER) primary production and optical databases, from which daily integrated rates of carbon fixation in the absence of UVR are calculated as a function of depth for a 140 km transect line sampled between dawn and dusk of a single day (14 November 1991). The UVR measurements from the nearby NSF/OPP Polar Network at Palmer Station are used to determine ozone (O 3 ) concentration on the day of the transect, which is then employed in Madronich's (In UV‐B Radiation and Ozone Depletion (Edited by M. Tevini), pp. 17–68. Lewis, Boca Raton, FL, 1993) spectral code to model daytime variations in surface spectral irradiances under clear sky conditions. These data are corrected for cloudiness and then combined with estimates of in‐water UVR spectral attenuation coefficients, derived from Icecolors 90 data, to estimate in situ light exposure for phytoplankton collected at different depths and locations. An absolute chlorophyllspecific biological weighting function (BWF), determined under natural solar light fields for Antarctic diatom communities and shown to be reproducible while differing from a laboratory diatom BWF and other in situ BWF determined for other phytoplankton assemblages, is combined with estimates of in situ UVR exposure to derive in situ estimates of chlorophyllspecific losses of carbon fixation due to UVR inhibittion. By repeating calculations for every sampling site along the transect, we derive a spatial map of estimated UVR effects on primary production across the ...