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- Filipsson, Helena, et al.
(författare)
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A culture-based calibration of benthic foraminiferal paleotemperature proxies : δ18O and Mg/Ca results
- 2010
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 7:4, s. 1335-1347
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Tidskriftsartikel (refereegranskat)abstract
- Benthic foraminifera were cultured for five months at four temperatures (4, 7, 14 and 21 degrees C) to establish the temperature dependence of foraminiferal calcite delta O-18 and Mg/Ca. Two Bulimina species (B. aculeata and B. marginata) were most successful in terms of calcification, adding chambers at all four temperatures and reproducing at 7 and 14 degrees C. Foraminiferal delta O-18 values displayed ontogenetic variations, with lower values in younger individuals. The delta O-18 values of adult specimens decreased with increasing temperature in all but the 4 degrees C treatment, exhibiting a relationship consistent with previous delta O-18 paleotemperature calibration studies. Foraminiferal Mg/Ca values, determined by laser ablation inductively coupled plasma mass spectrometry, were broadly consistent with previous Mg/Ca calibration studies, but extremely high values in the 4 degrees C treatment and higher than predicted values at two of the other three temperatures make it challenging to interpret these results.
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| 3. |
- Filipsson, Helena L., et al.
(författare)
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Seasonal variability of stable carbon isotopes (δ13CDIC) in the Skagerrak and the Baltic Sea : Distinguishing between mixing and biological productivity
- 2017
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182. ; 483, s. 15-30
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Tidskriftsartikel (refereegranskat)abstract
- We documented the annual cycle of the carbon isotopic composition of dissolved inorganic carbon (δ13CDIC) in the water columns of the Skagerrak and Baltic Sea to obtain an increased understanding of the processes involved controlling the carbon isotopic distribution in shelf seas. The lowest δ13CDIC values (-4.9‰) were found in the low-oxygen, brackish Baltic bottom water whereas the highest values (+1.8‰) were observed in the surface water of the Skagerrak during late summer. Photosynthesis drove the high δ13CDIC values (between 1.0 and 1.8‰) noted in the surface waters of both the Skagerrak and the Baltic. The δ13CDIC values below the halocline in the Baltic reflect mixing of brackish water and the more saline water from the Skagerrak, and foremost organic matter remineralization processes that release significant amounts of low-δ13C CO2. Similarly, in the stagnant fjord basins, little deep water exchange and the degradation of terrestrial and marine organic matter set the δ13C composition. Deep-water renewal in the fjord basins resulted in rapid increases of the δ13CDIC on the order of 1‰, whereas remineralization processes caused a decrease in δ13CDIC of 0.1-0.3‰ per month depending on location. The combined effects of water mixing and remineralization processes (estimated using apparent oxygen utilization (AOU) values) yielded the expression: δ13CDIC =0.032*S-0.01*AOU-0.12 for the Baltic - Skagerrak region at water depths below the halocline.
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