Publication Date:
2015-01-16
Description:
Subpolar regions are key areas to study natural climate variability due to their high sensitivity to rapid environmental changes, particularly through sea surface temperature (SST) variations. Here, we have tested three independent organic temperature proxies (UK'37, TEX86 and LDI) on their potential applicability for SST reconstruction in the subpolar region around Iceland. UK'37, TEX86 and TEXL86 temperature estimates from suspended particulate matter result in a substantial discrepancy with instrumental data, while long chain alkyl diols were below detection limit in most of the stations. In the northern Iceland basin sedimenting particles revealed a seasonality in lipid fluxes similar to that in the bulk flux and the net primary production, i.e. highest flux of alkenones and GDGTs were measured during late spring-summer, and late summer for long chain alkyl diols. The flux-weighted average temperature estimates had a significant negative (ca. 2.3 °C for UK'37) and positive (up to 5 °C for TEX86) offset with satellite-derived SSTs and the temperature derived from the underlying surface sediment. In contrast, sedimentary UK'37 estimates temperatures around Iceland correlate well with summer mean temperatures, while TEX86 derived temperatures correspond well with either annual or winter mean 0–200 m temperatures, suggesting a subsurface temperature signal. Anomalous LDI-SST values in surface sediments, and low mass flux of 1,13- and 1,15-diols compared to 1,14-diols, suggest that Proboscia diatom is the major source of long chain alkyl diols in this area rather than eustigmatophyte algae, and therefore the LDI cannot be applied in this region.
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
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