Salinity Effects on the Isolation and Subsequent Molecular-Level Characterization of Dissolved Organic Matter.
Abstract
Several studies have demonstrated that dissolved organic matter (DOM) characteristics change down estuarine gradients. These changes are often attributed to photochemical and microbial degradation as well as mixing with different DOM sources. In this study, we collected freshwater DOM and treated it by mixing with artificial seawater. After isolating the DOM with common techniques (C18 solid phase extraction and stirred cell ultrafiltration), we collected mass spectra via electrospray ionization mass spectrometry (ESI-MS) and analyzed the data with principal components analysis and discriminant analysis. Results from these experiments show that when freshwater DOM is subjected to changes in salinity prior to isolation, the isolated DOM assumes characteristics different from those of the initial freshwater DOM isolated in the same manner. These molecular-level changes may result from conformational changes in the DOM as a result of the salinity increase or from shifts in the retention characteristics of ultrafiltration and C18 membranes due to changes in ionic strength. In either case, the resulting fractionation of the DOM may help to explain the relative lack of identifiable terrestrial DOM in the global ocean.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.B32B..06D
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling (0412;
- 0793;
- 1615;
- 4805;
- 0428 Carbon cycling (4806);
- 0442 Estuarine and nearshore processes (4235);
- 0452 Instruments and techniques;
- 0458 Limnology (1845;
- 4239;
- 4942)