How Well Do Optical and Geochemical Properties of Terrestrial DOM Correlate in the Coastal Ocean?
Abstract
Terrestrial inputs of DOM to the coastal ocean are important features of the marine carbon cycle. The optical and chemical properties of terrestrial DOM are related, but these bulk properties are difficult to resolve when mixing of other DOM sources occurs in coastal waters. Molecular chemical information, such as the stable isotope values of DOM and dissolved lignin, are more specific to DOM sources, yet few systematic studies have sought to correlate these measurements with the optical properties of chromophoric DOM (CDOM). Results from measurements of DOM optics and chemistry for the Atchafalaya River estuary in the northern Gulf of Mexico and from the North Sea-Baltic Sea mixing near Denmark, indicate a better agreement between short wave DOM absorption (<350 nm) and chemical properties of DOM (carbon stable isotopes and lignin) than long wave absorption (>400 nm). DOC stable isotope values were isotopically-depleted (<-25‰) when CDOM absorption was high, and isotopically-enriched (ca. -21±2‰) when CDOM absorption was low, approaching zero. More variability in DOC stable isotope values occurred for the Baltic Sea than did for the Atchafalaya Estuary in the northern Gulf of Mexico. However, in both systems, dissolved lignin concentration was strongly correlated to CDOM absorption The non-chromophoric fraction of DOM, and that which will not be sensed remotely, was roughly 70 μM C in both systems. The similarity of regression and mixing models relating DOM optics and chemistry between these two coastal environments will be discussed.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMOS53C1337O
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling (0412;
- 0793;
- 1615;
- 4805;
- 4912);
- 4806 Carbon cycling (0428);
- 4850 Marine organic chemistry (0470;
- 1050)