Photodegradation of dissolved organic matter (DOM) due to ultraviolet (UV) exposure
can have important consequences for coastal zone productivity. The availability of UV
radiation to aquatic environments has increased due to ozone depletion. Chromophoric
DOM affects the amount of light penetration in a water column. Ecosystem productivity
depends in part on the input of DOM into a coastal zone. DOM can protect animals,
plants, and microbes from damaging UV light by acting as sunscreen, resulting in
increased ecosystem productivity. Alternatively, DOM can decrease ecosystem
productivity by absorbing light needed for photosynthesis and forming reaction products
that are harmful to coastal zone biota. Increased urbanization of watersheds and seasonal
differences in weather patterns change the delivery pathways, reactivity, input, and
energy flow of DOM into aquatic systems. Understanding the input and reactivity of DOM in coastal systems as a function of land urbanization and season will help
determine the fate of irradiated organic matter and its potential role as a sunscreen in
coastal waters. The consequences of energy flow from UV radiation to DOM in aquatic
systems will provide useful preliminary data to be used for land-use planning in tributary
regions. This study also provides data useful for predictive models of the fate of
irradiated organic chemicals and the resultant impact on water quality. In this paper, the
study of watershed urbanization and season on the input and photodegradation of DOM
in coastal waters is discussed based on organic carbon analysis, UV-Visible
spectrophotometry, microbial processing of DOM, and terrestrial (land-use) analysis.
University of Minnesota M.S. thesis. May 2012. Major: Water resources science. Advisor: Dr. Elizabeth C. Minor. 1 computer file (PDF); v, 72 pages.
Macdonald, Megan J..
Photochemical and microbial degradation of dissolved organic matter in the Lake Superior watershed..
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