Computer Science
Scientific paper
Jan 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995gecoa..59...33c&link_type=abstract
Geochimica et Cosmochimica Acta, vol. 59, Issue 1, pp.33-46
Computer Science
10
Scientific paper
The elemental and major biochemical compositions of the relict f-turbidite sampled in two cores from the Madeira Abyssal Plain were determined. This fine-grained, distal sequence occurs at ca. 9 m core depth and includes a surficial oxidized horizon defined by a distinct color change. Oxygen diffused downward through sediments above this interface and in ca. 10 kyr destroyed 80% of the organic substances that below the front had survived degradation in the presence of porewater sulfate for ca. 140 kyr. These deposits provide an opportunity to establish the extent and selectivity of oxic sedimentary degradation under natural conditions without the usual complications of bioturbation and varying sources or sedimentation rates. In both cores, a sample from the upper oxidized layer was compared to two samples from the underlying unoxidized layers. The unoxidized sequences of both turbidities contained 0.93-1.02 wt% organic carbon (OC) and 0.10-0.11 wt% total nitrogen (TN). Approximately 20% of the initial OC and 40% of the initial TN remained in the oxidized horizons, with a consequent decrease in atomic C/N ratio from ca. 11 to ca. 5. All samples gave very low yields of lignin phenols and comparable OC-normalized yields of total aldoses and amino acids, and indicated predominantly marine organic matter (OM) and nonselective oxic degradation of these biochemical classes. Compositions of individual aldoses and amino acids generally were also similar in surface and deep sediments, except that the oxidized horizons yielded markedly elevated (3-5X) percentages of nonprotein amino acids. This study clearly demonstrates that prolonged exposure to OZ can lead to organic matter alteration which is far more extensive than that obtained with sulfate alone. In comparison to early diagenesis, however, alteration of the measured biochemicals was largely nonselective. Such oxidation reactions could control the distribution and composition of organic matter in slowly accumulating continental rise and deep-ocean environments.
Cowie Gregory L.
de Lance G. J.
Hedges John I.
Prahl Fredrick G.
No associations
LandOfFree
Elemental and major biochemical changes across an oxidation front in a relict turbidite: An oxygen effect does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Elemental and major biochemical changes across an oxidation front in a relict turbidite: An oxygen effect, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Elemental and major biochemical changes across an oxidation front in a relict turbidite: An oxygen effect will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1820900