Detres, Y. University of Puerto Rico, ydetres@hotmail.com
Armstrong, R. University of Puerto Rico, neptune@caribe.net

 
AGING STUDY OF FILTERS USED IN UV-B SUPPLEMENTATION AND EXCLUSION EXPERIMENTS
 
Controlled studies of the effects of UV-B (280 - 320 nm) on plants by exclusion and supplementation experiments, require the use of different filters for the attenuation of desired wavelengths. Six commonly used materials were evaluated to assess changes in their optical properties trough time. The materials included cellulose monoacetate, Mylar polyester film, polycarbonate sheets (Lexan XL, Lexan MR5, Hyzod) and the acrylic material OP4 were exposed to natural sunlight and to UV-B artificial lamps for up to 60 days. The transmission spectra for each filter were measured spectrophotometrically at regular intervals for wavelengths ranging from 280 to 700 nm. Surface irradiance during the experimental period was determined for 305nm, 320nm, 340nm, 380nm and PAR bands using a GUV-511 radiometer. Cellulose monoacetate and Mylar filters showed 10 to 15% reductions in transmittance in the UV region. All the polycarbonate filters had stable transmittance in the UV region but showed reductions of 10 to 15% in the visible wavelengths. This needs to be considered when using these materials in long-term experiments.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: CS65WE1080S