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Book ; Online ; Thesis: Benthic Foraminifera as Proxies in Contourite Drift Systems

Saupe, Anna [Verfasser] / Grunert, Patrick [Gutachter] / Schmiedl, Gerhard [Gutachter]

2023

Author's details	Anna Saupe ; Gutachter: Patrick Grunert, Gerhard Schmiedl
Keywords	Geowissenschaften ; Earth Sciences
Subject code	sg550
Language	English
Publisher	Universitäts- und Stadtbibliothek Köln
Publishing place	Köln
Document type	Book ; Online ; Thesis
Database	Digital theses on the web

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Book ; Online: Monsoon-driven changes in aeolian and fluvial sediment input to the central Red Sea recorded throughout the last 200 000 years

Ehrmann, Werner / Wilson, Paul A. / Arz, Helge W. / Schulz, Hartmut / Schmiedl, Gerhard

eISSN: 1814-9332

2024

Abstract: Climatic and associated hydrological changes controlled the transport processes and composition of the sediments in the central Red Sea during the last ca. 200 kyr. Three different source areas for mineral dust are identified. The dominant source is ... ...

Abstract	Climatic and associated hydrological changes controlled the transport processes and composition of the sediments in the central Red Sea during the last ca. 200 kyr. Three different source areas for mineral dust are identified. The dominant source is located in the eastern Sahara (Sudan and southernmost Egypt). We identify its imprint on Red Sea sediments by high smectite and Ti contents, low 87 Sr / <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="527256ea34e0af356380afd605ccefc0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cp-20-37-2024-ie00001.svg" width="8pt" height="14pt" src="cp-20-37-2024-ie00001.png"/></svg:svg> 86 Sr, and high ε Nd . The availability of deflatable sediments was controlled by the intensity of tropical rainfall and vegetation cover over North Africa linked to the African monsoon. Intense dust input to the Red Sea occurred during arid phases, and low input occurred during humid phases. A second, less significant source indicated by palygorskite input is probably located on the eastern Arabian Peninsula and/or Mesopotamia, while the presence of kaolinite suggests an additional minor dust source in northern Egypt. Our grain size data reflect episodes of fluvial sediment discharge to the central Red Sea and document the variable strength in response to all of the precession-paced insolation maxima during our study interval including both those that were strong enough to trigger sapropel formation in the eastern Mediterranean Sea and those that were not. The African humid period most strongly expressed in our Red Sea record was the one during the Eemian last interglacial at ca. 125 ka (when the Baraka River was far more active than today), followed by those at 198, 108, 84, and 6 ka.
Subject code	333 ; 550
Language	English
Publishing date	2024-01-03
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Stable carbon isotopes in paleoceanography: atmosphere, oceans, and sediments

Mackensen, Andreas / Schmiedl, Gerhard

Earth-science reviews. 2019 Oct., v. 197

2019

Abstract: Carbon is one of the key elements in organisms and non-living compounds on Earth. Carbon dioxide and methane are important greenhouse gases in the atmosphere, dissolved inorganic (DIC) and organic carbon (DOC) determine water biogeochemistry, and ... ...

Abstract	Carbon is one of the key elements in organisms and non-living compounds on Earth. Carbon dioxide and methane are important greenhouse gases in the atmosphere, dissolved inorganic (DIC) and organic carbon (DOC) determine water biogeochemistry, and carbonates are major constituents of marine sediments. Stable carbon isotope ratios (13C/12C), expressed as δ13C values, are widely used in modern Earth sciences. δ13CCO2 values of atmospheric carbon dioxide reflect global climate evolution and change. Marine δ13CDIC is used as water-mass tracer and helps quantifying the anthropogenic CO2 uptake of the ocean. The δ13C values of fossil planktic and benthic carbonates indicate changes in circulation pattern and deep-water ventilation of ancient oceans, as well as paleoproductivity at the sea surface and methane release at the sea floor. The δ13COM values of sedimentary organic matter (OM) and compound-specific δ13C values of molecular organic biomarkers indicate whether the organic carbon is of marine or terrestrial provenience. Secular δ13C variations and excursions in carbonates are important stratigraphic marker and tie points.Here we review the application of stable carbon isotope ratios in ocean water and biogenic carbonates as proxies in paleoceanography, including the atmospheric and sedimentary reservoirs oceanic carbon is in exchange with. Due to the wide use of δ13C values in Earth sciences, this overview necessarily does not claim to be complete; rather we focus on field-based stable carbon isotope research and its significance in paleoceanography. This may assist in evaluating general circulation model results and foster development of new innovative proxies.
Keywords	General Circulation Models ; biogeochemistry ; biomarkers ; carbon dioxide ; carbonates ; climatology ; fossils ; greenhouse gases ; marine sediments ; methane ; oceans ; organic carbon ; paleoceanography ; provenance ; seawater ; stable isotopes
Language	English
Dates of publication	2019-10
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	1792-9
ISSN	0012-8252
ISSN	0012-8252
DOI	10.1016/j.earscirev.2019.102893
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: A deep-learning automated image recognition method for measuring pore patterns in closely related bolivinids and calibration for quantitative nitrate paleo-reconstructions.

Govindankutty Menon, Anjaly / Davis, Catherine V / Nürnberg, Dirk / Nomaki, Hidetaka / Salonen, Iines / Schmiedl, Gerhard / Glock, Nicolaas

Scientific reports

2023 Volume 13, Issue 1, Page(s) 19628

Abstract: Eutrophication is accelerating the recent expansion of oxygen-depleted coastal marine environments. Several bolivinid foraminifera are abundant in these oxygen-depleted settings, and take up nitrate through the pores in their shells for denitrification. ... ...

Abstract	Eutrophication is accelerating the recent expansion of oxygen-depleted coastal marine environments. Several bolivinid foraminifera are abundant in these oxygen-depleted settings, and take up nitrate through the pores in their shells for denitrification. This makes their pore density a possible nitrate proxy. This study documents three aspects related to the porosity of bolivinids. 1. A new automated image analysis technique to determine the number of pores in bolivinids is tested. 2. The pore patterns of Bolivina spissa from five different ocean settings are analysed. The relationship between porosity, pore density and mean pore size significantly differs between the studied locations. Their porosity is mainly controlled by the size of the pores at the Gulf of Guayaquil (Peru), but by the number of pores at other studied locations. This might be related to the presence of a different cryptic Bolivina species in the Gulf of Guayaquil. 3. The pore densities of closely related bolivinids in core-top samples are calibrated as a bottom-water nitrate proxy. Bolivina spissa and Bolivina subadvena showed the same correlation between pore density and bottom-water nitrate concentrations, while the pore density of Bolivina argentea and Bolivina subadvena accumeata is much higher.
Language	English
Publishing date	2023-11-10
Publishing country	England
Document type	Journal Article
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-023-46605-y
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: North Sea salt-marsh archives trace past storminess and climate variability

Bunzel, Dorothea / Milker, Yvonne / Müller-Navarra, Katharina / Arz, Helge Wolfgang / Schmiedl, Gerhard

Global and planetary change. 2021 Mar., v. 198

2021

Abstract: Intertidal coastal wetlands are regularly exposed to storm surges and associated flooding, resulting in the recurrent accretion of reworked sediments on the salt-marsh surfaces. In this context, well-stratified salt-marsh sediment sequences provide an ... ...

Abstract	Intertidal coastal wetlands are regularly exposed to storm surges and associated flooding, resulting in the recurrent accretion of reworked sediments on the salt-marsh surfaces. In this context, well-stratified salt-marsh sediment sequences provide an exceptional archive to evaluate the response of coastal wetlands to past storm-climate variability. Hence, this study focusses on the investigation of two sedimentary salt-marsh sequences from the south-eastern German North Sea coast (Bay of Tümlau and Friedrichskoog) to understand how and to which extent changes in the storm-surge climate are transferred into the sediment archive. This objective is particularly challenging as German mainland salt marshes have been greatly altered by human activities over the last century. To overcome this problem, this study combines different sedimentological and geochemical proxy data, using mean grain sizes together with ln(Br/Cl), Br/Cₒᵣg, and ln(Zr/Rb) ratios, to allow for the identification of storm-surge layers. Local changes in the sedimentary organic matter supply are reflected by the ln(Br/Cl) ratio. There, abrupt drops in the ln(Br/Cl) data coincide with relatively coarser textured sand layers, indicating impacts by regional storm surges during winter, while intervals of comparable higher ln(Br/Cl) values may represent deposition during spring to fall. The Br/Cₒᵣg record reflects the marine versus terrestrial organic matter input and reveals a long-term increase starting during the first half of the 20th century towards recent times, resembling the observed amplification in North Sea storminess. A similar trend is reflected by the ln(Zr/Rb) ratio (since 1950 CE), which can be used as a proxy for the grain-size distribution. Periodic fluctuations in the ln(Zr/Rb) ratio at inter-decadal timescales (10–19 years) suggest a close linkage between local sediment accretion and large-scale atmosphere-ocean climate oscillations over the North Atlantic and Europe, and thus related storm-surge frequency and intensity. Periodic variability on decadal scales was also identified in the ln(Br/Cl) record at the less human-modified and more naturally developed salt marsh at the Bay of Tümlau (12–22 years), likewise indicating a relation between North Sea storminess and associated shifts in the seasonal signal of the primary production and sediment texture to oscillations in the atmosphere-ocean system. On the contrary, similar periodicities are lacking for the intense modified salt marsh at Friedrichskoog. Apparently, the salt-marsh depositional system in the Bay of Tümlau reacts more sensitively to super-regional climatic changes, respectively, the natural depositional processes in the salt marsh at Friedrichskoog are superimposed by the more intense local human activities.
Keywords	climate ; coasts ; humans ; littoral zone ; organic matter ; primary productivity ; salt marshes ; sand ; sediment texture ; spring ; storms ; winter ; Europe ; North Sea
Language	English
Dates of publication	2021-03
Publishing place	Elsevier B.V.
Document type	Article
Note	NAL-AP-2-clean
ZDB-ID	2016967-X
ISSN	0921-8181
ISSN	0921-8181
DOI	10.1016/j.gloplacha.2020.103403
Database	NAL-Catalogue (AGRICOLA)

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Book ; Online: Monsoon-driven changes in aeolian and fluvial sediment input to the central Red Sea recorded throughout the last 200,000 years

Ehrmann, Werner / Wilson, Paul A. / Arz, Helge W. / Schulz, Hartmut / Schmiedl, Gerhard

eISSN: 1814-9332

2023

Abstract	Climatic and associated hydrological changes controlled the transport processes and composition of the sediments in the central Red Sea during the last ca. 200 kyr. Three different source areas for mineral dust are identified. The dominant source is located in the eastern Sahara (Sudan and southernmost Egypt). We identify its imprint on Red Sea sediments by high smectite and Ti contents, high 87 Sr/ 86 Sr and low ε Nd . The availability of deflatable sediments was controlled by the intensity of tropical rainfall and vegetation cover over northern Africa linked to the African monsoon. Intense dust input to the Red Sea occurred during arid phases, low input during humid phases. A second, less significant source indicated by palygorskite input is probably located on the eastern Arabian Peninsula and/or Mesopotamia, while the presence of kaolinite suggests an additional minor dust source in northern Egypt. Our grain size data reflect episodes of fluvial sediment discharge to the central Red Sea and document the variable strength in response to all of the precession-paced insolation maxima during our study interval including both those that were strong enough to trigger sapropel formation in the eastern Mediterranean Sea and those that were not. The African Humid Period most strongly expressed in our Red Sea record was the one during the Eemian last interglacial at ca. 125 ka, followed by those at 198 ka, 108 ka, 84 ka and 6 ka.
Subject code	550 ; 333
Language	English
Publishing date	2023-06-06
Publishing country	de
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Are They Everywhere? – Benthic Foraminifera From Saline Springs in Central Germany

Milker, Yvonne / Schönfeld, Joachim / Meng, Stefan / Wrozyna, Claudia / Schneppmüller, Martin / Schmiedl, Gerhard

2023

Abstract: Benthic foraminifera have rarely been reported from saline springs in Germany. To fill this gap, we investigated live (Rose Bengal stained) and dead benthic foraminifera from saline ponds, springs, and meadows in central Germany. For foraminiferal ... ...

Abstract	Benthic foraminifera have rarely been reported from saline springs in Germany. To fill this gap, we investigated live (Rose Bengal stained) and dead benthic foraminifera from saline ponds, springs, and meadows in central Germany. For foraminiferal investigations, we collected surface samples along transects with changes in vegetation at Sülldorf in Saxony-Anhalt, in Artern and close to Auleben, Luisenhall, and Esperstedt in Thuringia. We found live and dead foraminifera at all investigated saline locations. We observed seven different agglutinated species that commonly inhabit coastal salt marshes (Trochamminita irregularis, Trochamminita salsa, Entzia macrescens, Miliammina fusca, Siphotrochammina lobata, Haplophragmoides manilaensis, and Haplophragmoides wilberti), one agglutinated species, Entzia sp., which has not been described to date, and one calcareous species, Gordiospira arctica, which has earlier been described from shallow-water settings at high northern latitudes. We hypothesize that foraminifera have been repeatedly transported to the inland saline habitats in central Germany by migratory birds on their routes from northern and southern Europe probably since the early Holocene. Future genetic investigations of the species in central Germany and comparisons with sequenced specimens from other localities will provide a better understanding of their provenance and phylogenetic position.
Subject code	590
Language	English
Publishing date	2023-11-30
Publisher	Chusman Foundation for Foraminiferal Research
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: A deep-learning automated image recognition method for measuring pore patterns in closely related bolivinids and calibration for quantitative nitrate paleo-reconstructions

Govindankutty Menon, Anjaly / Davis, Catherine V. / Nürnberg, Dirk / Nomaki, Hidetaka / Salonen, Iines / Schmiedl, Gerhard / Glock, Nicolaas

2023

Abstract	Eutrophication is accelerating the recent expansion of oxygen-depleted coastal marine environments. Several bolivinid foraminifera are abundant in these oxygen-depleted settings, and take up nitrate through the pores in their shells for denitrification. This makes their pore density a possible nitrate proxy. This study documents three aspects related to the porosity of bolivinids. 1. A new automated image analysis technique to determine the number of pores in bolivinids is tested. 2. The pore patterns of Bolivina spissa from five different ocean settings are analysed. The relationship between porosity, pore density and mean pore size significantly differs between the studied locations. Their porosity is mainly controlled by the size of the pores at the Gulf of Guayaquil (Peru), but by the number of pores at other studied locations. This might be related to the presence of a different cryptic Bolivina species in the Gulf of Guayaquil. 3. The pore densities of closely related bolivinids in core-top samples are calibrated as a bottom-water nitrate proxy. Bolivina spissa and Bolivina subadvena showed the same correlation between pore density and bottom-water nitrate concentrations, while the pore density of Bolivina argentea and Bolivina subadvena accumeata is much higher.
Subject code	551
Language	English
Publishing date	2023-11-10
Publisher	Nature Research
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Intensity of African Humid Periods Estimated from Saharan Dust Fluxes.

Ehrmann, Werner / Schmiedl, Gerhard / Beuscher, Sarah / Krüger, Stefan

PloS one

2017 Volume 12, Issue 1, Page(s) e0170989

Abstract: North Africa experienced dramatic changes in hydrology and vegetation during the late Quaternary driven by insolation-induced shifts of the tropical rain belt and further modulated by millennial-scale droughts and vegetation-climate feedbacks. While most ...

Abstract	North Africa experienced dramatic changes in hydrology and vegetation during the late Quaternary driven by insolation-induced shifts of the tropical rain belt and further modulated by millennial-scale droughts and vegetation-climate feedbacks. While most past proxy and modelling studies concentrated on the temporal and spatial dynamics of the last African humid period, little is known about the intensities and characteristics of pre-Holocene humid periods. Here we present a high-resolution record of fine-grained eastern Saharan dust from the Eastern Mediterranean Sea spanning the last 180 kyr, which is based on the clay mineral composition of the marine sediments, especially the kaolinite/chlorite ratio. Minimum aeolian kaolinite transport occurred during the African Humid Periods because kaolinite deflation was hampered by increased humidity and vegetation cover. Instead, kaolinite weathering from kaolinite-bearing Cenozoic rocks was stored in lake basins, river beds and soils during these periods. During the subsequent dry phases, fine-grained dust was mobilised from the desiccated lakes, rivers and soils resulting in maximum aeolian uptake and transport of kaolinite. The kaolinite transport decreased again when these sediment sources exhausted. We conclude that the amount of clay-sized dust blown out of the Sahara into the Eastern Mediterranean Sea is proportional to the intensity of the kaolinite weathering and accumulation in soils and lake sediments, and thus to the strength of the preceding humid period. These humid periods provided the windows for the migration of modern humans out of Africa, as postulated previously. The strongest humid period occurred during the Eemian and was followed by two weaker phases centred at ca. 100 ka and ca. 80 ka.
MeSH term(s)	Africa, Northern ; Aluminum Silicates/chemistry ; Droughts ; Dust/analysis ; Geologic Sediments/analysis ; Geologic Sediments/chemistry ; Humans ; Humidity ; Lakes ; Rain ; Rivers ; Tropical Climate
Chemical Substances	Aluminum Silicates ; Dust ; clay (1302-87-0)
Language	English
Publishing date	2017
Publishing country	United States
Document type	Journal Article
ISSN	1932-6203
ISSN (online)	1932-6203
DOI	10.1371/journal.pone.0170989
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Recent benthic foraminiferal distribution in the Elbe Estuary (North Sea, Germany)

Francescangeli, Fabio / Milker, Yvonne / Bunzel, Dorothea / Thomas, Helmuth / Norbisrath, Mona / Schönfeld, Joachim / Schmiedl, Gerhard

A response to environmental stressors

2021

Abstract: Highlights • Investigations of the benthic foraminiferal distribution in the Elbe Estuary. • Low diverse assemblages are dominated by Ammonia species. • Low salinities and high-frequency dredging confines foraminiferal proliferation. • Over 40 years, ... ...

Abstract	Highlights • Investigations of the benthic foraminiferal distribution in the Elbe Estuary. • Low diverse assemblages are dominated by Ammonia species. • Low salinities and high-frequency dredging confines foraminiferal proliferation. • Over 40 years, changes in hydrodynamic conditions induced assemblage modifications. Abstract For the past 200 years, estuarine environments experienced intense and rapid environmental degradations due to human interventions. In addition, Global Changes are modifying the estuarine physiography, leading to a re-structuration of marginal marine benthic communities. The aim of this study is to document, the modern assemblage composition and the species-environment relations of benthic foraminifera upstream the Elbe Estuary (southern North Sea) and to observe what has changed since the first survey in 1981. For this purpose, a surface sampling was carried out from 22 stations along the transitional area of the Elbe Estuary. Living (rose-Bengal stained) and dead foraminiferal assemblages were analysed as well as hydrological and sedimentological parameters (such as salinity, pH, grain-size, and organic matter). Living faunas are characterized by very low densities and largely dominated by Ammonia species. Dead assemblages are more diverse and dominated by Ammonia aomoriensis, Haynesina germanica, and Cribroelphidium selseyense. Salinity and grain-size seem to be the major factors influencing foraminiferal distributions in the transitional area. Under the ongoing climate changes, future strategies will be taken to foster the application of benthic foraminifera as biomonitoring tool in the Elbe Estuary, via this baseline investigation.
Subject code	550
Language	English
Publisher	Elsevier
Publishing country	de
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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