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Park, Eunmi; Hefter, Jens; Fischer, Gerhard; Mollenhauer, Gesine (2018): Fractional abundances and concentrations of GDGT collected by sediment trap moored in the eastern Atlantic upwelling regimes. PANGAEA, https://doi.org/10.1594/PANGAEA.886701, Supplement to: Park, E et al. (in press): TEX86 in sinking particles in three eastern Atlantic upwelling regimes. Organic Geochemistry, https://doi.org/10.1016/j.orggeochem.2018.07.015

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Abstract:
Seasonal variations in fluxes of isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) and the estimated temperatures based on TEX86 are examined in sinking particles collected using moored sediment traps in the eastern Atlantic upwelling regions. In the equatorial Guinea Basin, GDGT fluxes show a correlation with opal fluxes, implying that GDGTs are mainly transported via aggregation with diatoms. The flux-weighted TEXH86 temperatures derived from particles collected both at 853 m and 3,921 m depth correspond to the water temperature (24.1 °C) of ca. 50 m depth, where nitrate concentration starts to increase, potentially as a consequence of nitrification by Thaumarchaeota. This suggests that nutrient concentrations may affect the depth habitat of Thaumarchaeota, and it determines at which water depth the TEXH86 temperature is recorded. In the coastal upwelling off Namibia, TEXH86 temperatures are similar to satellite-derived sea surface temperature (SST) during the warm season, but the record derived from the trap is delayed relative to the SST by approximately 26 days. Warm biases, however, occur during the cold season, similar to what has previously been observed in the filamentous upwelling region off Cape Blanc. In both coastal upwelling regions, oxygen minimum zones (OMZs) are a common feature, and higher TEX86 values have been found within the OMZs in the water column off Cape Blanc and elsewhere. Thus, contributions from GDGTs produced in OMZs might explain the warmer temperature estimates during the cold season in both regions. We thus conclude that in the eastern Atlantic upwelling system, TEXH86 temperature estimates are influenced by non-thermal factors such as nutrient depth distributions and GDGTs produced in the OMZ. In paleoenvironmental records of TEX86, non-thermal signals have to be considered on regional scales.
Related to:
Vorrath, Maria-Elena; Lahajnar, Niko; Fischer, Gerhard; Miti Libuku, Viktor; Schmidt, Martin; Emeis, Kay-Christian (2018): Spatiotemporal variation of vertical particle fluxes and modelled chlorophyll a standing stocks in the Benguela Upwelling System. Journal of Marine Systems, 180, 59-75, https://doi.org/10.1016/j.jmarsys.2017.12.002
Wefer, Gerold; Fischer, Gerhard (1993): Seasonal patterns of vertical particle flux in equatorial and coastal upwelling areas of the eastern Atlantic. Deep Sea Research Part I: Oceanographic Research Papers, 40(8), 1613-1645, https://doi.org/10.1016/0967-0637(93)90019-Y
Further details:
Lampitt, Richard Stephen; Antia, Avan N; Fischer, Gerhard (2006): Particle fluxes from sediment trap GBN3. PANGAEA, https://doi.org/10.1594/PANGAEA.357371
Coverage:
Median Latitude: -16.386115 * Median Longitude: 5.011402 * South-bound Latitude: -25.481700 * West-bound Longitude: -11.133300 * North-bound Latitude: 1.800000 * East-bound Longitude: 13.090000
Date/Time Start: 1989-03-01T00:00:00 * Date/Time End: 2000-09-05T00:00:00
Size:
3 datasets

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