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- Title
Risk analysis of dissolved organic matter-mediated ultraviolet B exposure in Canadian inland waters.
- Authors
Molot, L. A.; Keller, W.; Leavitt, P. R.; Robarts, R. D.; Waiser, M. J.; Arts, M. T.; Clair, T. A.; Pienitz, R.; Yan, N. D.; McNicol, D. K.; Prairie, Y. T.; Dillon, P. J.; Macrae, M.; Bello, R.; Nordin, R. N.; Curtis, P. J.; Smol, J. P.; Douglas, M. S. V.
- Abstract
With depleted ozone levels and the possibility that climate change might lower dissolved organic matter (DOM) concentrations, the risk of exposure of fresh waters in Canada to ultraviolet B (UV-B) was evaluated. First, the distribution of a UV-B-sensitive zooplankton genus, Daphnia, was examined as a function of DOM concentration and maximum depth (Zmax) in 258 systems. Distribution was not restricted by UV-B, although very clear, shallow systems are underrepresented. Secondly, the depth at which 1% of surface radiance at 320 nm occurs (Z320,1%) was compared with Zmax in over 1000 aquatic systems in 15 ecozones to determine the proportions of optically clear systems (Zmax ≤ Z320,1%) and systems that may become clear (i.e., are "at risk") should DOM decrease by 50%. South of the treeline, <6% of systems were clear, with the exception of two ecozones with 10%–20%. The proportion of systems at risk was 0% in most regions, with 5%–9% in four regions. DOM levels appear adequate to prevent extirpation of sensitive taxa like Daphnia through direct exposure to UV-B in most regions south of the treeline. However, optically clear and at-risk ponds were much more common in the three Artic ecozones, especially the Northern Arctic and Arctic Cordillera.
- Subjects
CANADA; RISK assessment; ORGANIC compound content of seawater; ULTRAVIOLET radiation; RIVERS
- Publication
Canadian Journal of Fisheries & Aquatic Sciences, 2004, Vol 61, Issue 12, p2511
- ISSN
0706-652X
- Publication type
Article
- DOI
10.1139/F04-165