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Full-Text Articles in Physical Sciences and Mathematics

Dissolved And Particulate Organic Matter Source-Age Characterization In The Upper And Lower Chesapeake Bay: A Combined Isotope And Biochemical Approach, An Loh, Je Bauer, Ea Canuel May 2006

Dissolved And Particulate Organic Matter Source-Age Characterization In The Upper And Lower Chesapeake Bay: A Combined Isotope And Biochemical Approach, An Loh, Je Bauer, Ea Canuel

VIMS Articles

In order to characterize the sources and ages of organic matter contributing to river and estuarine outflow waters, the present study investigated Delta C-14 and delta C-13 signatures of the major operationally defined biochemical classes of ultrafiltered dissolved organic matter (UDOM) in conjunction with lipid biomarker and elemental compositions of UDOM and suspended particulate organic matter (POM) in the Chesapeake Bay. Freshwater (Susquehanna River) UDOM was dominated by a molecularly uncharacterized (MUC) fraction, followed by total carbohydrate (TCHO), total hydrolysable amino acid (THAA) and total lipid (TLE) components. In contrast, UDOM at the bay mouth (salinity similar to 22-24) was …


Bioreactivity Of Estuarine Dissolved Organic Matter: A Combined Geochemical And Microbiological Approach, Sl Mccallister, Je Bauer, Elizabeth A. Canuel Jan 2006

Bioreactivity Of Estuarine Dissolved Organic Matter: A Combined Geochemical And Microbiological Approach, Sl Mccallister, Je Bauer, Elizabeth A. Canuel

VIMS Articles

An integrated multidisciplinary study utilizing geochemical and microbial ecological approaches was conducted to characterize the origins, chemical nature, and quantities of dissolved and particulate organic matter (OM) utilized by heterotrophic bacteria in a temperate estuary. C: N, stable isotope (delta C-13), and lipid biomarker analyses revealed differences in the inferred reactivity of autochthonous versus allochthonous OM sources. Isotopic comparison of OM size fractions and bacterial nucleic acids suggests that high-molecular-weight dissolved OM (DOM) is consistently linked to bacterial biomass synthesis along the estuarine salinity gradient. Polyunsaturated fatty acids (as percent of total fatty acids, FA) were a reliable predictor of …


Sediment Biogeochemistry Of Northern Cascadia Margin Shallow Gas Hydrate Systems, John W. Pohlman Jan 2006

Sediment Biogeochemistry Of Northern Cascadia Margin Shallow Gas Hydrate Systems, John W. Pohlman

Dissertations, Theses, and Masters Projects

Methane contained in gas hydrate is a significant component of the global organic carbon inventory. Describing the methane sources supporting these systems and the mechanisms that control the distribution of methane in marine sediments are critical elements in evaluating the resource potential, climate change implications and geologic hazards associated with gas hydrate. The northern Cascadia margin (offshore Vancouver Island, Canada) is a convergent margin with gas hydrate-bearing cold seeps composed of both thermogenic (Barkley Canyon) and microbial (Bullseye vent) gas sources. Gas hydrate and sediment cores were collected from each of these settings to examine the sources that sustain the …