In:
Paleoceanography, American Geophysical Union (AGU), Vol. 12, No. 4 ( 1997-08), p. 604-614
Abstract:
The δ 15 N records of two sediment cores from the Angola Basin have been used to investigate past changes in nutrient utilization in the surface waters of this highly productive region. Low 15 N/ 14 N ratios in the cores (from 〉 3000 m water depth) generally correspond to low sea surface temperatures and high sedimentary organic content, demonstrating a link between upwelling, productivity, and the degree of nitrate depletion. Glacial δ 15 N was lower by 0.5–0.7‰, and paleoproductivity was elevated by around 30% relative to interglacial periods, indicating that although productivity was higher, nitrate was less depleted during glacial than interglacial periods. More pronounced than the glacial/interglacial changes in δ 15 N values of both cores are precession‐related (23 kyr) fluctuations. These cyclic δ 15 N variations, which are in phase with those of paleoproductivity and sea surface temperature, indicate that changes in trade wind driven upwelling intensity and the advection of cold, nutrient‐rich water from the south drive nutrient availability and productivity off the southwest coast of Africa. No strong evidence was found from sedimentary δ 15 N values for denitrification in the water column in the Angola Basin during the past 180 kyr.
Type of Medium:
Online Resource
ISSN:
0883-8305
,
1944-9186
Language:
English
Publisher:
American Geophysical Union (AGU)
Publication Date:
1997
detail.hit.zdb_id:
637876-6
detail.hit.zdb_id:
2015231-0
detail.hit.zdb_id:
2916554-4
SSG:
16,13
SSG:
13
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