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Early diagenesis of chlorophyll in a...

Chen, Nianhong.

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Early diagenesis of chlorophyll in a river-dominated margin.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Early diagenesis of chlorophyll in a river-dominated margin./
Author:	Chen, Nianhong.
Description:	162 p.
Notes:	Chair: Thomas S. Bianchi.
Contained By:	Dissertation Abstracts International63-03B.
Subject:	Biogeochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3046639
ISBN:	0493605789

Early diagenesis of chlorophyll in a river-dominated margin.
Chen, Nianhong.

Early diagenesis of chlorophyll in a river-dominated margin. - 162 p.

Chair: Thomas S. Bianchi.

Thesis (Ph.D.)--Tulane University, 2002.

It has been estimated that 80% of the organic carbon preserved in marine sediments occurs in “terrigenous-deltaic” regions near river mouths. The Louisiana coast, which contains the most prolific deltaic regions in the U.S. (Atchafalaya and Mississippi rivers), provides an excellent field laboratory to compare the effects of differential sedimentation rates and redox conditions on organic carbon burial using pigments as biomarkers.

ISBN: 0493605789Subjects--Topical Terms:

545717
Biogeochemistry.

Early diagenesis of chlorophyll in a river-dominated margin.
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005 20110426
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020 $a 0493605789
035 $a (UnM)AAI3046639
035 $a AAI3046639
040 $a UnM $c UnM
100 1 $a Chen, Nianhong. $3 1251717
245 1 0 $a Early diagenesis of chlorophyll in a river-dominated margin.
300 $a 162 p.
500 $a Chair: Thomas S. Bianchi.
500 $a Source: Dissertation Abstracts International, Volume: 63-03, Section: B, page: 1221.
502 $a Thesis (Ph.D.)--Tulane University, 2002.
520 $a It has been estimated that 80% of the organic carbon preserved in marine sediments occurs in “terrigenous-deltaic” regions near river mouths. The Louisiana coast, which contains the most prolific deltaic regions in the U.S. (Atchafalaya and Mississippi rivers), provides an excellent field laboratory to compare the effects of differential sedimentation rates and redox conditions on organic carbon burial using pigments as biomarkers.
520 $a Application of HPLC/MS has led to identification of high concentrations of bacteriopigments in sediments collected in area with recorded hypoxia on the Louisiana shelf. This confirmed the development of anaerobic photosynthetic community (purple and green sulfur bacteria) over a large deltaic area. Downcore distributions of bacteriopigments in sediments indicated the highest concentrations occurred between 1960 and the present, coinciding with increased nutrient loading from the Mississippi River.
520 $a Four novel decay products, esters of carotenols and chlorins (carotenol chlorins esters, CCEs), were also identified in sediments from the LA shelf. Our laboratory copepod grazing experiment confirmed that similar to sterol chlorin esters (SCEs), CCEs can be produced through zooplankton grazing on diatom, providing excellent class-specific biomarkers of zooplankton grazing on phytoplankton. Pigment inventories indicated that pheophytin-<italic>a </italic>, pyropheophytin-<italic>a</italic>, chlorophyllone-<italic>a</italic>, CCEs and SCEs were major decay products in LA shelf sediments. Absence of the two grazing biomarkers, CCEs and SCEs, in river sediments suggested that grazing activity was minimal in river waters. However, chlorophyllone-<italic> a</italic> was present in river sediments and its abundance in river sediments was comparable with that in shelf sediments. This suggested that chlorophyllone-<italic> a</italic> was not closely associated with grazing like CCEs and SCEs. Downcore distribution of pigments, bulk organic carbon and nitrogen, and radioactive isotopes (<super>210</super>Pb, <super>137</super>Cs, <super>7</super>Be) suggested that a 9–10 cm surface mixed layer was common for samples collected in areas with low sedimentation. It was observed that pigment decay rate constants in the mixed layer were greater than the accumulation layer by 1–3 orders of magnitude. Decay rates of pigments in the upper mixed layer were variable and primarily dependent upon differences in the inherent lability of pigment compounds and bulk carbon, while in the accumulation layer all pigments decayed at similar rates.
590 $a School code: 0235.
650 4 $a Biogeochemistry. $3 545717
650 4 $a Engineering, Marine and Ocean. $3 1019064
650 4 $a Geochemistry. $3 539092
690 $a 0425
690 $a 0547
690 $a 0996
710 2 0 $a Tulane University. $3 1019475
773 0 $t Dissertation Abstracts International $g 63-03B.
790 $a 0235
790 1 0 $a Bianchi, Thomas S., $e advisor
791 $a Ph.D.
792 $a 2002
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3046639