Removing UV-A and UV-C radiation from UV-B fluorescent lamp emissions. Differences in the inhibition of photosynthesis in the marine alga Dunaliella tertiolecta using chromate versus cellulose acetate-polyester filters.
Ultraviolet-B (UV-B; 280-320 nm)-emitting lamps unavoidably emit ultraviolet-A (UV-A; 320-400 nm) and ultraviolet-C (UV-C; <280 nm) radiation. Short-wavelength-blocking filters are generally used to limit the wave bands of UV under investigation. The widespread use of such filters means that all exposures to UV-B radiation will have a significant UV-A component. Therefore, the physiological effects unique to UV-B exposure are difficult to clearly isolate. This study presents a method to remove the UV-A and UV-C "contamination" using a liquid potassium chromate (K(2)CrO(4)) filter, thus allowing more direct assessment of the effects of UV-B exposure. Cultures of the green marine alga Dunaliella tertiolecta were grown in the absence of UV radiation. Sunlamps supplied the UV radiation for a 24 h exposure (solar radiation was not used in this study). The UV radiation was filtered either by the standard method (i.e. cellulose acetate (CA) with polyester = Mylar controls) or by a liquid filter of potassium chromate. Photosynthetic responses were compared. Major decreases in the ratio of variable to maximal fluorescence in dark-adapted cells and photosynthetic capacity were observed in CA-filtered cultures, whereas no change was observed in cells exposed to the same UV-B flux with the UV-A removed by K(2)CrO(4). The use of a CA filter with a Mylar control does not link results unequivocally to UV-B radiation. Such results should be interpreted with caution.
White
Andrea L
AL
Department of Plant Biology, University of New Hampshire, Durham, NH 03824, USA.
Jahnke
Leland S
LS
D002482:Cellulose / Q000031:analogs & derivatives*; D002840:Chromates; D056890:Eukaryota / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D005374:Filtration; D005453:Fluorescence; D008029:Lighting; D008386:Marine Biology; D010788:Photosynthesis / Q000528:radiation effects*; D011091:Polyesters; D012623:Seawater / Q000382:microbiology; D013057:Spectrum Analysis; D014466:Ultraviolet Rays
D002840:Chromates; D011091:Polyesters; C005062:acetylcellulose; D002482:Cellulose