 |
| Titel |
Seasonal hydrology drives rapid shifts in the flux and composition of dissolved and particulate organic carbon and major and trace ions in the Fraser River, Canada |
| VerfasserIn |
B. M. Voss, B. Peucker-Ehrenbrink, T. I. Eglinton, R. G. M. Spencer, E. Bulygina, V. Galy, C. H. Lamborg, P. M. Ganguli, D. B. Montluçon, S. Marsh, S. L. Gillies, J. Fanslau, A. Epp, R. Luymes |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 19 ; Nr. 12, no. 19 (2015-10-01), S.5597-5618 |
| Datensatznummer |
250118109
|
| Publikation (Nr.) |
 copernicus.org/bg-12-5597-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Rapid changes in the volume and sources of discharge during the spring
freshet lead to pronounced variations in biogeochemical properties in
snowmelt-dominated river basins. We used daily sampling during the onset of
the freshet in the Fraser River (southwestern Canada) in 2013 to identify
rapid changes in the flux and composition of dissolved material, with a
focus on dissolved organic matter (DOM). Previous time series sampling (at
twice monthly frequency) of dissolved inorganic species in the Fraser River
has revealed smooth seasonal transitions in concentrations of major ions and
tracers of water and dissolved load sources between freshet and base flow
periods. In contrast, daily sampling reveals a significant increase in
dissolved organic carbon (DOC) concentration (200 to 550 μmol L−1)
occurring over a matter of days, accompanied by a shift in DOM optical
properties, indicating a transition towards higher molecular weight, more
aromatic DOM composition. Comparable changes in DOM composition, but not
concentration, occur at other times of year, underscoring the role of
seasonal climatology in DOM cycling. A smaller data set of total and
dissolved Hg concentrations also showed variability during the spring
freshet period, although dissolved Hg dynamics appear to be driven by
factors beyond DOM as characterized here. The time series records of DOC and
particulate organic carbon (POC) concentrations indicate that the Fraser
River exports 0.25–0.35 % of its annual basin net primary productivity.
The snowmelt-dominated hydrology, forested land cover, and minimal reservoir
impoundment of the Fraser River may influence the DOC yield of the basin,
which is high relative to the nearby Columbia River and of similar magnitude
to that of the Yukon River to the north. Anticipated warming and decreased
snowfall due to climate changes in the region may cause an overall decrease
in DOM flux from the Fraser River to the coastal ocean in coming decades |
| |
|
| Teil von |
|
|
|
|
|
|
|
|