Environmental variability in the reactivity of freshwater dissolved organic carbon to UV-B

Author: Clair T.A.  

Publisher: Springer Publishing Company

ISSN: 0168-2563

Source: Biogeochemistry, Vol.36, Iss.1, 1997-01, pp. : 89-97

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Abstract

Reductions in the global stratospheric ozone layer are thought to be increasing the amount of ultraviolet B (UV-B) radiation reaching the planet's surface and may be affecting the chemistry of dissolved organic carbon (DOC) in surface waters. We studied the abundance of chromophores in DOC collected in four different aquatic environments in southwestern Nova Scotia using ^13C nuclear magnetic resonance (^13C NMR) spectroscopy. We showed a clear seasonal pattern in the distribution of structural carbon related to light-sensitive chromophores. There seemed to be little variation in the UV-B related chemical structure of DOC between lakes and streams, though water from a bog pool showed large differences from the other samples. These patterns of potential UV-B reactivity tend to be dampened however, by variations in DOC concentrations which also occur seasonally.