Distribution and export of isoprenoid tetraether lipids in suspended particulate matter from the water column of the Western Atlantic Ocean

Sarah J. Hurley, Julius S. Lipp, Hilary Close, Kai Uwe Hinrichs, Ann Pearson

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The TEX86 paleotemperature proxy is based on the distribution of archaeal glycerol dibiphytanyl glycerol tetraether (GDGT) lipids preserved in marine sediments, yet both the influence of different physiological factors on the structural distribution of GDGTs and the mechanism(s) by which GDGTs is(are) exported to marine sediments remain(s) unresolved. We investigated the abundance and structural distribution of GDGTs in the South-west and Equatorial Atlantic Ocean in four water column profiles spanning 48 degrees of latitude. The depth distribution was consistent with production by ammonia-oxidizing Thaumarchaeota; maximum GDGT concentration occurred at the base of the NO2 maximum, core GDGTs dominated the structural distribution in surface waters above the NO2 maximum, and intact polar GDGTs – potentially indicating live cells – were more abundant below the NO2 maximum. Between 0 and1000 m, > 98% of the integrated GDGT inventory was present in waters at and below the NO2 maximum. Depth profiles of TEX86 temperature values displayed local minima at the NO2 maximum, while the ratio of GDGT-2:GDGT-3 increased with depth. A model based on the results predicts an average depth of origin for GDGTs exported to sediments between ca. 80–250 m. In the model, exported TEX86 values are remarkably insensitive to change in the average depth of origin of GDGTs. However, TEX86 values exported from the water column appear to reflect euphotic zone productivity, possibly due to the correlative intensity of organic matter remineralization providing substrates for ammonia oxidation. Predicting the influence of these regional controls on sedimentary TEX86 records requires a better understanding of the interaction between GDGT production, particle dynamics, and the depth of origin for exported organic matter.

Original languageEnglish (US)
Pages (from-to)90-102
Number of pages13
JournalOrganic Geochemistry
Volume116
DOIs
StatePublished - Feb 1 2018

Fingerprint

Particulate Matter
isoprenoid
Terpenes
suspended particulate matter
Glycerol
water column
lipid
Lipids
Water
ocean
marine sediment
ammonia
organic matter
remineralization
paleotemperature
euphotic zone
Sediments
vertical distribution
Ammonia
Biological materials

Keywords

  • Export
  • GDGT
  • Intact polar lipids
  • Suspended particulate matter
  • TEX

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

Distribution and export of isoprenoid tetraether lipids in suspended particulate matter from the water column of the Western Atlantic Ocean. / Hurley, Sarah J.; Lipp, Julius S.; Close, Hilary; Hinrichs, Kai Uwe; Pearson, Ann.

In: Organic Geochemistry, Vol. 116, 01.02.2018, p. 90-102.

Research output: Contribution to journalArticle

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abstract = "The TEX86 paleotemperature proxy is based on the distribution of archaeal glycerol dibiphytanyl glycerol tetraether (GDGT) lipids preserved in marine sediments, yet both the influence of different physiological factors on the structural distribution of GDGTs and the mechanism(s) by which GDGTs is(are) exported to marine sediments remain(s) unresolved. We investigated the abundance and structural distribution of GDGTs in the South-west and Equatorial Atlantic Ocean in four water column profiles spanning 48 degrees of latitude. The depth distribution was consistent with production by ammonia-oxidizing Thaumarchaeota; maximum GDGT concentration occurred at the base of the NO2 − maximum, core GDGTs dominated the structural distribution in surface waters above the NO2 − maximum, and intact polar GDGTs – potentially indicating live cells – were more abundant below the NO2 − maximum. Between 0 and1000 m, > 98{\%} of the integrated GDGT inventory was present in waters at and below the NO2 − maximum. Depth profiles of TEX86 temperature values displayed local minima at the NO2 − maximum, while the ratio of GDGT-2:GDGT-3 increased with depth. A model based on the results predicts an average depth of origin for GDGTs exported to sediments between ca. 80–250 m. In the model, exported TEX86 values are remarkably insensitive to change in the average depth of origin of GDGTs. However, TEX86 values exported from the water column appear to reflect euphotic zone productivity, possibly due to the correlative intensity of organic matter remineralization providing substrates for ammonia oxidation. Predicting the influence of these regional controls on sedimentary TEX86 records requires a better understanding of the interaction between GDGT production, particle dynamics, and the depth of origin for exported organic matter.",
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AB - The TEX86 paleotemperature proxy is based on the distribution of archaeal glycerol dibiphytanyl glycerol tetraether (GDGT) lipids preserved in marine sediments, yet both the influence of different physiological factors on the structural distribution of GDGTs and the mechanism(s) by which GDGTs is(are) exported to marine sediments remain(s) unresolved. We investigated the abundance and structural distribution of GDGTs in the South-west and Equatorial Atlantic Ocean in four water column profiles spanning 48 degrees of latitude. The depth distribution was consistent with production by ammonia-oxidizing Thaumarchaeota; maximum GDGT concentration occurred at the base of the NO2 − maximum, core GDGTs dominated the structural distribution in surface waters above the NO2 − maximum, and intact polar GDGTs – potentially indicating live cells – were more abundant below the NO2 − maximum. Between 0 and1000 m, > 98% of the integrated GDGT inventory was present in waters at and below the NO2 − maximum. Depth profiles of TEX86 temperature values displayed local minima at the NO2 − maximum, while the ratio of GDGT-2:GDGT-3 increased with depth. A model based on the results predicts an average depth of origin for GDGTs exported to sediments between ca. 80–250 m. In the model, exported TEX86 values are remarkably insensitive to change in the average depth of origin of GDGTs. However, TEX86 values exported from the water column appear to reflect euphotic zone productivity, possibly due to the correlative intensity of organic matter remineralization providing substrates for ammonia oxidation. Predicting the influence of these regional controls on sedimentary TEX86 records requires a better understanding of the interaction between GDGT production, particle dynamics, and the depth of origin for exported organic matter.

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