In:
Paleoceanography, American Geophysical Union (AGU), Vol. 14, No. 2 ( 1999-04), p. 118-134
Abstract:
Treatment of diatom microfossils from Southern Ocean sediments with hot perchloric acid leaves a “diatom‐bound” N fraction which is 0–4‰ lower in δ 15 N than the bulk sediment, typically 3‰ lower in recent Antarctic diatom ooze. Results from Southern Ocean surface sediments indicate that early diagenetic changes in bulk sediment N content and δ 15 N are not reflected in diatom‐bound N, suggesting that diatom‐bound N is physically protected from early diagenesis by the microfossil matrix. A meridional transect of multicores from the Indian sector of the Southern Ocean shows a northward increase in the δ 15 N of diatom‐bound N, suggesting that diatom‐bound δ 15 N, like bulk sedimentary δ 15 N, varies with nitrate utilization in the overlying surface waters. The δ 15 N of diatom‐bound N is 3–4‰ higher in glacial age Antarctic sediments than in Holocene sediments, supporting the hypothesis, previously based on bulk sediment δ 15 N, that nitrate utilization in the surface Antarctic was higher during the last ice age. While there are important uncertainties, the inferred range of utilization changes could potentially explain the entire ∼80 ppm amplitude of observed glacial/interglacial variations in atmospheric CO 2 .
Type of Medium:
Online Resource
ISSN:
0883-8305
,
1944-9186
DOI:
10.1029/1998PA900018
Language:
English
Publisher:
American Geophysical Union (AGU)
Publication Date:
1999
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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