CS36 Ultraviolet Radiation
Date: Friday, June 14, 2002
Time: 9:00:00 AM
Location: Sidney
 
HargreavesBR, Lehigh University, Bethlehem, USA, brh0@lehigh.edu
Morris, D, P, Lehigh University, Bethlehem, USA, 
Zagarese, H, E, Universidad Nacional del Comahue, Bariloche, Argentina, 
Ferraro, M, , Universidad Nacional del Comahue, Bariloche, Argentina, 
Aņon Suarez, D, , Universidad Nacional del Comahue, Bariloche, Argentina, 
Soto, D, , Universidad Austral de Chile, Puerto Montt, Chile, 
 
UV ATTENUATION & CDOM PROPERTIES OF MID TO HIGH LATITUDE SOUTHERN HEMISPHERE LAKES
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Over 3 years we have studied >83 lakes from Argentina, Chile, & the Antarctic peninsula to determine summer UV attenuation & related factors such as algal biomass, DOC concentration, water chemistry, CDOM spectral slope & photolability. The lowest UV attenuation was typically in lakes with low DOC, a condition associated with low productivity and minimal watershed vegetation. We developed a laboratory test for photolability of CDOM in natural waters (48-hour exposure of filtered lake samples and humic acid standards in quartz tube to QP-340 lamps having UV spectral properties similar to sunlight). Photolability rates were correlated inversely with alkalinity & UV-B spectral slope. Among the explanations for variation in photolability is variation in CDOM influx rate relative to the rate of its removal by photochemical and microbial processes.