Calibration of alkenone unsaturation ratios (U[sup k[prime]][sub 37]) for paleotemperature estimation in cold polar waters

Journal Article · Thu Apr 01 04:00:00 EST 1993 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(93)90120-L· OSTI ID:6390296

Sikes, E L ^[1]; Volkman, J K ^[2]

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1. Univ. of Tasmania (Australia)
2. Cooperative Research Centre for Antarctic and Southern Ocean Environment and CSIRO Division of Oceanography, Hobart, Tasmania (Australia)

C[sub 37]-C[sub 39] long-chain unsaturated ketones (alkenones) and alkenes were identified in samples of particulate organic matter obtained from surface waters spanning the temperature range [minus]0.7-12.2[degrees]C in the Southern Ocean south of Australia. The carbon number distribution indicates that these compounds are derived from the prymnesiophyte alga Emiliania huxleyi which is the predominant coccolithophorid in these waters. Values of U[sup k[prime]][sub 37] were calculated according to the definition U[sup k[prime]][sub 37] = [37:2]/([37:2] + [37:3]), where [37:[chi]] is the concentration of the C[sub 37] alkenone with [chi] double bonds, and plotted against sea surface temperature (SST). The data form a contiguous set with earlier compilations of data from warmer waters. Over much of the temperature range the relationship between U[sup k[prime]][sub 37] and temperature is remarkably linear, and is best fitted by the simple equation U[sup k[prime]][sub 37] = 0.0414T - 0.156 (for temperatures 4-25[degrees]C). This calibration of U[sup k[prime]][sub 37] with temperature for field samples is significantly different from that established from analyses of prymnesiophyte algae in culture, and it diverges especially at the colder temperatures. Data for temperatures below about 4-6[degrees]C show increased scatter and the calibration at these low temperatures may be better fitted by a nonlinear exponential function, but this requires further testing. Certainly, the predictive power of the linear calibration is severely constained at temperatures less than 5.0[degrees]C, but at temperatures above this the data establish the usefulness of U[sub k[prime]][sub 37] as an SST indicator for waters north of the polar front in the Southern Ocean and for several regions of the world ocean.

• OSTI ID: 6390296
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 57:8; ISSN GCACAK; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
ALGAE
ALKENES
ATLANTIC OCEAN
CONCENTRATION RATIO
ECOLOGICAL CONCENTRATION
HYDROCARBONS
KETONES
MATHEMATICS
NONLINEAR PROBLEMS
ORGANIC COMPOUNDS
PALEOCLIMATOLOGY
PALEONTOLOGY
PLANTS
REGRESSION ANALYSIS
SEAS
STATISTICS
SURFACE WATERS
TEMPERATURE MEASUREMENT
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K