Simulation of Ozone Depletion Using Ambient Irradiance Supplemented with UV Lamps

S. DÍAZ,1 S. GIANESELLA,10 M. GOSSELIN,11 C. NOZAIS,12 É. PELLETIER,13 I. SCHLOSS,14 M. VERNET,15 C. CAMILIÓN,2 J. ESCOBAR,3 G. DEFERRARI,4 S. ROY,5 K. LACOSTE,6 S. DEMERS,7 C. BELZILE,8 AND G. FERREYRA9

PHOTOCHEMISTRY AND PHOTOBIOLOGY

Año: 2006 p. 857 - 864

0031-8655

In studies of the biological effects of UV radiation, ozone depletion can be mimicked by performing the study under ambient conditions and adding radiation with UV-B lamps. We present here a discussion on this methodology for three different locations along a latitudinal gradient: Rimouski (Canada), Ubatuba (Brazil) and Ushuaia (Argentina). Experiments on the effect of potential ozone depletion on marine ecosystems were carried out in large outdoor enclosures (mesocosm). In all localities we simulated irradiances corresponding to 60% ozone depletion, which may produce between 130 and 1900% increase in 305 nm irradiance, at noon, depending on site and season. Supplementing with a fixed percentage of ambient irradiance provides a better simulation of irradiance increase due to ozone depletion than supplementing with a fixed irradiance value, particularly near sunrise and sunset or under cloudy sky conditions. Calculations performed for Ushuaia showed that, in very cloudy days, supplementation by the square wave method may produce unrealistic irradiances. Differences between the spectra of the calculated supplementing irradiance and the lamp, for a given site and date, will be a function of the time of day and may become more or less pronounced according to the biological weighting function of the effect under study.