Albert Benthien

Albert Benthien
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research | AWI

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32
Publications
2,533
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1,155
Citations
Citations since 2017
6 Research Items
421 Citations
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080
2017201820192020202120222023020406080

Publications

Publications (32)
Preprint
RATIONALE Boron isotopes are a powerful tool for pH reconstruction in marine carbonates and as tracer for fluid-mineral interaction in geochemistry. Micro-analytical approaches based on laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) often suffer from effects induced by the sample matrix. In this study, we...
Article
Full-text available
The boron isotopic composition (δ11B) of benthic foraminifera provides a valuable tool to reconstruct past deep-water pH. As the abundance of monospecific species might be limited in sediments, microanalytical techniques can help to overcome this problem, but such studies on benthic foraminiferal δ11B are sparse. In addition, microanalytics provide...
Article
Full-text available
The boron isotopic composition (δ 11 B) of benthic foraminifera provides a valuable tool to reconstruct past deep-water pH. As the abundance of monospecific species might be limited in sediments, microanalytical techniques can help to overcome this problem, but such studies on benthic foraminiferal δ 11 B are sparse. In addition, microanalytics pro...
Article
Full-text available
Methane emissions from peat bogs are mitigated by methanotrophs, which live in symbiosis with peat moss (e.g. Sphagnum). Here, we investigate the influence of temperature and resultant changes in methane fluxes on Sphagnum and methanotroph-related biomarkers, evaluating their potential as proxies in ancient bogs. A pulse-chase experiment using 13C-...
Article
Full-text available
Authentic biomarker standards were obtained from algal cultures in an attempt to accurately determine blank C added during sample processing for compound-specific radiocarbon analysis. Emiliania huxleyi and Thalassiosira pseudonana were grown under manipulated Δ14C dissolved inorganic carbon (DIC) levels and chlorophyll a and either alkenones (E. h...
Article
The boron isotopic composition of planktonic foraminiferal shell calcite (δ11BCc) provides valuable information on the pH of ambient water at the time of calcification. Hence, δ11BCc of fossil surface-dwelling planktonic foraminifera can be used to reconstruct ancient aqueous pCO2 if information on a second carbonate system parameter, temperature a...
Article
The hydrogen isotopic (δD) composition of long-chain alkenones produced by certain haptophyte algae has been suggested as a potential proxy for reconstructing paleo sea surface salinity. However, environmental parameters other than salinity may also affect the δD of alkenones. We investigated the impact of the level of irradiance on hydrogen isotop...
Article
The hydrogen isotopic composition (δD) of long-chain alkenones derived from haptophyte algae has recently been applied as paleo sea surface salinity proxy, but this application has been complicated by reported differences in δD of individual C37 alkenones of up to 45‰. Here we show that this difference in D/H ratios is the result of the desaturatio...
Article
Full-text available
Peat bogs are primarily situated at mid to high latitudes and future climatic change projections indicate that these areas may become increasingly wetter and warmer. Methane emissions from peat bogs are reduced by symbiotic methane oxidizing bacteria (methanotrophs). Higher temperatures and increasing water levels will enhance methane production, b...
Presentation
Culture studies of Emiliania huxleyi and Gephyrocapsa oceanica grown at different salinities and different temperatures and, as a consequence, different growth rates showed that there is a strong correlation between the fractionation factor Alphaalkenones-growthwater and salinity for both E. huxleyi and G. oceanica (Schouten et al., 2006). The hydr...
Article
A potential new tool for paleo-salinity reconstructions uses the hydrogen isotopic composition of long-chain alkenones produced mainly by the coccolithophorid species Emiliania huxleyi and Gephyrocapsa oceanica. Using culture experiments, it has been shown that the fractionation between D/H composition of the water and C37-alkenones is relatively c...
Article
Reconstructing the long-term history of the partial pressure of atmospheric carbon dioxide (pCO2) is a big challenge in paleoclimatic and paleoceanographic research. Hence, a number of proxies have been proposed to estimate paleo-CO2 concentrations at time periods prior to those covered by ice cores. Two of the most prominent proxy approaches are (...
Article
Full-text available
We report a detailed programmed-temperature pyrolysis/combustion methodology for radiocarbon (14C) dating of Antarctic sub-ice shelf sediments. The method targets the autochthonous organic component in sediments that contain a distribution of acid-insoluble organic components from several sources of different ages. The approach has improved sedimen...
Data
We investigated the effect of CO2 and primary production on the carbon isotopic fractionation of alkenones and particulate organic matter (POC) during a natural phytoplankton bloom dominated by the coccolithophore Emiliania huxleyi. In nine semi-closed mesocosms (~11 m**3 each), three different CO2 partial pressures (pCO2) in triplicate represented...
Article
We investigated the effect of CO2 and primary production on the carbon isotopic fractionation of alkenones and particulate organic matter (POC) during a natural phytoplankton bloom dominated by the coccolithophore Emiliania huxleyi. In nine semi-closed mesocosms (∼11 m3 each), three different CO2 partial pressures (pCO2) in triplicate represented g...
Article
Recent studies have revealed that lateral transport and focusing of particles strongly influences the depositional patterns of organic matter in marine sediments. Transport can occur in the water column prior to initial deposition or following sediment re-suspension. In both cases, fine-grained particles and organic-rich aggregates are more suscept...
Article
Full-text available
Two haptophyte algae, Emiliania huxleyi and Gephyrocapsa oceanica, were cultured at different temperatures and salinities to investigate the impact of these factors on the hydrogen isotopic composition of long chain alkenones synthesized by these algae. Results showed that alkenones synthesized by G. oceanica were on average depleted in D by 30‰ co...
Article
Full-text available
Two haptophyte algae, Emiliania huxleyi and Gephyrocapsa oceanica , were cultured at different temperatures and salinities to investigate the impact of these factors on the hydrogen isotopic composition of long chain alkenones synthesized by these algae. Results showed that alkenones synthesized by G. oceanica were on average depleted in D by 30 co...
Article
The carbon isotopic fractionation (εp) of the C37:2 alkenone was analysed for 19 South Atlantic sediment samples from the Last Glacial Maximum (LGM). Our study covers the equatorial and subtropical ocean including the coastal upwelling regions off South Africa, the equatorial upwelling, and the oligotrophic western basins. The results were compared...
Article
We studied the direct effects of CO<sub>2</sub> and related changes in seawater carbonate chemistry on marine planktonic organisms in a mesocosm experiment. In nine outdoor enclosures (∼11 m<sup>3</sup> each), the partial pressure of $\text{CO}_{2}(\text{pCO}_{2})$ in the seawater was modified by an aeration system. The triplicate mesocosm treatmen...
Article
Full-text available
1] We compared ocean atlas values of surface water [PO 4 3À ] and [CO 2 (aq)] against the carbon isotopic fractionation (e p) of alkenones obtained from surface sediments of the South Atlantic and the central Pacific (Pacific data are from Pagani et al. [2002]). We observed a positive correlation between e p and 1/[CO 2 (aq)], which is opposite of...
Data
We compared ocean atlas values of surface water [PO4]3- and [CO2(aq)] against the carbon isotopic fractionation (ep) of alkenones obtained from surface sediments of the South Atlantic and the central Pacific (Pacific data are from Pagani et al. 2002, doi:10.1029/2002PA000756). We observed a positive correlation between ep and 1/[CO2(aq)], which is...
Article
A calibration of the alkenone paleotemperature index UK'37, derived from 370 surface sediment samples from the global ocean between 60°N and 60°S (Müller et al., 1998), revealed a linear relationship (UK'37 = 0.033 T + 0.044) to sea surface temperatures (SST). Regional studies based on euphotic zone particulate organic matter (POM), however, showed...
Article
The carbon isotopic composition of the C37-alkenones has been used in various paleoceanographic studies to estimate the ancient surface water CO2 concentration [CO2aq]. A number of recent culture, field and sediment studies, however, indicate that the carbon isotopic fractionation in haptophyte algae is predominantly controlled by physiological pro...
Article
Reconstruction of past surface water nutrient concentration is crucial to understand the processes responsible for lowering the atmospheric carbon dioxide by ~90 ppmv during the Last Glacial Maximum compared with peak interglacials. It has been demonstrated that the carbon isotopic composition in planktonic foraminiferal calcite is controlled by a...
Article
Full-text available
We have analyzed the stable carbon isotopic composition of the diunsaturated C37 alkenone in 29 surface sediments from the equatorial and South Atlantic Ocean. Our study area covers different oceanographic settings, including sediments from the major upwelling regions off South Africa, the equatorial upwelling, and the oligotrophic western South At...
Article
Discovering the driving mechanisms of varying atmospheric CO2 concentrations de- tected in polar ice cores is the big challenge of glacial/interglacial CO2 research. To define better the mechanisms by which oceanic and atmospheric levels of CO2 change, paleoceanic sources and sinks of carbon dioxide must be delineated. Besides other proxies, the ca...
Article
The carbon isotopic signal of the C37-alkenone, a taxon-specific biomarker for hap- tophyte algae, has been used in various paleoceanographic studies as a proxy for an- cient surface water CO2 concentration ([CO2aq]). However, a number of recent cul- ture, field and sediment studies imply that the carbon isotopic fractionation (ep) of alkenones is...
Data
We have analyzed the stable carbon isotopic composition of the diunsaturated C37 alkenone in 29 surface sediments from the equatorial and South Atlantic Ocean. Our study area covers different oceanographic settings, including sediments from the major upwelling regions off South Africa, the equatorial upwelling, and the oligotrophic western South At...
Article
We analysed the alkenone unsaturation ratio (U37/(K')) in 87 surface sediment samples from the western South Atlantic (5°N-50°S) in order to evaluate its applicability as a paleotemperature tool for this part of the ocean. The measured U37/(K') ratios were converted into temperature using the global core-top calibration of Muller et al. (1998) and...
Data
We analysed the alkenone unsaturation ratio (UK'37) in 87 surface sediment samples from the western South Atlantic (5°N-50°S) in order to evaluate its applicability as a paleotemperature tool for this part of the ocean. The measured UK'37 ratios were converted into temperature using the global core-top calibration of Müller et al. (1998, doi:10.101...

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