Articles | Volume 11, issue 23
Research article 08 Dec 2014
Research article | 08 Dec 2014
Dependence of the cyclization of branched tetraethers on soil moisture in alkaline soils from arid–subhumid China: implications for palaeorainfall reconstructions on the Chinese Loess Plateau
H. Wang et al.
No articles found.
Meng Xing, Weiguo Liu, and Jing Hu
Atmos. Chem. Phys. Discuss.,
Preprint withdrawnShort summary
Our results proved that below-cloud (BC) evaporation is the dominant BC processes in our study regions,reminding us to cautiously use the precipitation isotopic results;the impact of BC evaporation on the snowfall samples is weak,enhancing the confidence by using ice-cores to reconstruct the paleoclimates;and the isotopic method is more suitable to compute the evaporation remaining fraction in the high latitude areas,helping us to better evaluate the hydrological cycling processes.
Haiyan Ni, Ru-Jin Huang, Junji Cao, Weiguo Liu, Ting Zhang, Meng Wang, Harro A. J. Meijer, and Ulrike Dusek
Atmos. Chem. Phys., 18, 16363–16383,Short summary
Seasonal changes in organic carbon (OC) and elemental carbon (EC) sources in Xi'an, China, are investigated based on measurements of radiocarbon and the stable isotope 13C. Relative contributions to EC from biomass burning, coal combustion, and vehicle emissions change substantially between different seasons. Biomass burning contributes 60 % to the EC increment in winter. Comparing concentrations and sources of primary OC to total OC suggests non-negligible OC loss due to active photochemistry.
N. Jiao, C. Robinson, F. Azam, H. Thomas, F. Baltar, H. Dang, N. J. Hardman-Mountford, M. Johnson, D. L. Kirchman, B. P. Koch, L. Legendre, C. Li, J. Liu, T. Luo, Y.-W. Luo, A. Mitra, A. Romanou, K. Tang, X. Wang, C. Zhang, and R. Zhang
Biogeosciences, 11, 5285–5306,
Related subject area
Paleobiogeoscience: Proxy use, Development & ValidationCalibration of Mg ∕ Ca and Sr ∕ Ca in coastal marine ostracods as a proxy for temperatureTechnical note: Accelerate coccolith size separation via repeated centrifugationMg∕Ca, Sr∕Ca and stable isotopes from the planktonic foraminifera T. sacculifer: testing a multi-proxy approach for inferring paleotemperature and paleosalinityChemical destaining and the delta correction for blue intensity measurements of stained lake subfossil treesModern calibration of Poa flabellata (tussac grass) as a new paleoclimate proxy in the South AtlanticSeawater pH reconstruction using boron isotopes in multiple planktonic foraminifera species with different depth habitats and their potential to constrain pH and pCO2 gradientsBottom-water deoxygenation at the Peruvian margin during the last deglaciation recorded by benthic foraminiferaThe pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii)Benthic foraminifera as tracers of brine production in the Storfjorden “sea ice factory”Evaluation of bacterial glycerol dialkyl glycerol tetraether and 2H–18O biomarker proxies along a central European topsoil transectLeaf wax n-alkane patterns and compound-specific δ13C of plants and topsoils from semi-arid and arid MongoliaOrganic-carbon-rich sediments: benthic foraminifera as bio-indicators of depositional environmentsStrong correspondence between nitrogen isotope composition of foliage and chlorin across a rainfall gradient: implications for paleo-reconstruction of the nitrogen cycleEnvironmental and biological controls on Na∕Ca ratios in scleractinian cold-water coralsDepth habitat of the planktonic foraminifera Neogloboquadrina pachyderma in the northern high latitudes explained by sea-ice and chlorophyll concentrationsTemporal variability in foraminiferal morphology and geochemistry at the West Antarctic Peninsula: a sediment trap studySeasonality of archaeal lipid flux and GDGT-based thermometry in sinking particles of high-latitude oceans: Fram Strait (79° N) and Antarctic Polar Front (50° S)Long-chain diols in settling particles in tropical oceans: insights into sources, seasonality and proxiesMulti-trace-element sea surface temperature coral reconstruction for the southern Mozambique Channel reveals teleconnections with the tropical AtlanticOxygen isotope composition of the final chamber of planktic foraminifera provides evidence of vertical migration and depth-integrated growthMg ∕ Ca and δ18O in living planktic foraminifers from the Caribbean, Gulf of Mexico and Florida StraitsManganese incorporation in living (stained) benthic foraminiferal shells: a bathymetric and in-sediment study in the Gulf of Lions (NW Mediterranean)Effects of light and temperature on Mg uptake, growth, and calcification in the proxy climate archive Clathromorphum compactumA systematic look at chromium isotopes in modern shells – implications for paleo-environmental reconstructionsReviews and syntheses: Revisiting the boron systematics of aragonite and their application to coral calcificationPhysico-chemical and biological factors influencing dinoflagellate cyst production in the Cariaco BasinEffects of alkalinity and salinity at low and high light intensity on hydrogen isotope fractionation of long-chain alkenones produced by Emiliania huxleyiInterplay of community dynamics, temperature, and productivity on the hydrogen isotope signatures of lipid biomarkersBenthic foraminiferal Mn / Ca ratios reflect microhabitat preferencesThe effects of environment on Arctica islandica shell formation and architectureDiatoms as a paleoproductivity proxy in the NW Iberian coastal upwelling system (NE Atlantic)Factors controlling the depth habitat of planktonic foraminifera in the subtropical eastern North AtlanticThe effect of shell secretion rate on Mg / Ca and Sr / Ca ratios in biogenic calcite as observed in a belemnite rostrumCarbonate “clumped” isotope signatures in aragonitic scleractinian and calcitic gorgonian deep-sea coralsExamining the provenance of branched GDGTs in the Tagus River drainage basin and its outflow into the Atlantic Ocean over the Holocene to determine their usefulness for paleoclimate applicationsMussel shells of Mytilus edulis as bioarchives of the distribution of rare earth elements and yttrium in seawater and the potential impact of pH and temperature on their partitioning behaviorFossil invertebrates records in cave sediments and paleoenvironmental assessments – a study of four cave sites from Romanian CarpathiansTesting the D / H ratio of alkenones and palmitic acid as salinity proxies in the Amazon PlumeTechnical Note: Towards resolving in situ, centimeter-scale location and timing of biomineralization in calcareous meiobenthos – the calcein–osmotic pump methodA comparison of benthic foraminiferal Mn / Ca and sedimentary Mn / Al as proxies of relative bottom-water oxygenation in the low-latitude NE Atlantic upwelling systemThe stable isotopic composition of Daphnia ephippia reflects changes in δ13C and δ18O values of food and waterThe contribution of tephra constituents during biogenic silica determination: implications for soil and palaeoecological studiesSeasonal lake surface water temperature trends reflected by heterocyst glycolipid-based molecular thermometersTechnical Note: Silica stable isotopes and silicification in a carnivorous sponge Asbestopluma sp.Environmental controls on the boron and strontium isotopic composition of aragonite shell material of cultured Arctica islandicaGlobal analysis of seasonality in the shell flux of extant planktonic ForaminiferaBoron incorporation in the foraminifer Amphistegina lessonii under a decoupled carbonate chemistryOxygen and carbon isotope composition of modern planktic foraminifera and near-surface waters in the Fram Strait (Arctic Ocean) – a case studyUpper ocean mixing controls the seasonality of planktonic foraminifer fluxes and associated strength of the carbonate pump in the oligotrophic North AtlanticI/Ca ratios in benthic foraminifera from the Peruvian oxygen minimum zone: analytical methodology and evaluation as a proxy for redox conditions
Maximiliano Rodríguez and Christelle Not
Biogeosciences, 18, 1987–2001,Short summary
Mg/Ca in calcium carbonate shells of marine organisms such as foraminifera and ostracods has been used as a proxy to reconstruct water temperature. Here we provide new Mg/Ca–temperature calibrations for two shallow marine species of ostracods. We show that the water temperature in spring produces the best calibrations, which suggests the potential use of ostracod shells to reconstruct this parameter at a seasonal scale.
Hongrui Zhang, Chuanlian Liu, Luz María Mejía, and Heather Stoll
Biogeosciences, 18, 1909–1916,
Delphine Dissard, Gert Jan Reichart, Christophe Menkes, Morgan Mangeas, Stephan Frickenhaus, and Jelle Bijma
Biogeosciences, 18, 423–439,Short summary
Results from a data set acquired from living foraminifera T. sacculifer collected from surface waters are presented, allowing us to establish a new Mg/Ca–Sr/Ca–temperature equation improving temperature reconstructions. When combining equations, δ18Ow can be reconstructed with a precision of ± 0.5 ‰, while successive reconstructions involving Mg/Ca and δ18Oc preclude salinity reconstruction with a precision better than ± 1.69. A new direct linear fit to reconstruct salinity could be established.
Feng Wang, Dominique Arseneault, Étienne Boucher, Shulong Yu, Steeven Ouellet, Gwenaëlle Chaillou, Ann Delwaide, and Lily Wang
Biogeosciences, 17, 4559–4570,Short summary
Wood stain is challenging the use of the blue intensity technique for dendroclimatic reconstructions. Using stained subfossil trees from eastern Canadian lakes, we compared chemical destaining approaches with the
delta bluemathematical correction of blue intensity data. Although no chemical treatment was completely efficient, the delta blue method is unaffected by the staining problem and thus is promising for climate reconstructions based on lake subfossil material.
Dulcinea V. Groff, David G. Williams, and Jacquelyn L. Gill
Biogeosciences, 17, 4545–4557,Short summary
Tussock grasses that grow along coastlines of the Falkland Islands are slow to decay and build up thick peat layers over thousands of years. Grass fragments found in ancient peat can be used to reconstruct past climate because grasses can preserve a record of growing conditions in their leaves. We found that modern living tussock grasses in the Falkland Islands reliably record temperature and humidity in their leaves, and the peat they form can be used to understand past climate change.
Maxence Guillermic, Sambuddha Misra, Robert Eagle, Alexandra Villa, Fengming Chang, and Aradhna Tripati
Biogeosciences, 17, 3487–3510,Short summary
Boron isotope ratios (δ11B) of foraminifera are a promising proxy for seawater pH and can be used to constrain pCO2. In this study, we derived calibrations for new foraminiferal taxa which extend the application of the boron isotope proxy. We discuss the origin of different δ11B signatures in species and also discuss the potential of using multispecies δ11B analyses to constrain vertical pH and pCO2 gradients in ancient water columns to shed light on biogeochemical carbon cycling in the past.
Zeynep Erdem, Joachim Schönfeld, Anthony E. Rathburn, Maria-Elena Pérez, Jorge Cardich, and Nicolaas Glock
Biogeosciences, 17, 3165–3182,Short summary
Recent observations from today’s oceans revealed that oxygen concentrations are decreasing, and oxygen minimum zones are expanding together with current climate change. With the aim of understanding past climatic events and their relationship with oxygen content, we looked at the fossils, called benthic foraminifera, preserved in the sediment archives from the Peruvian margin and quantified the bottom-water oxygen content for the last 22 000 years.
Hannah K. Donald, Gavin L. Foster, Nico Fröhberg, George E. A. Swann, Alex J. Poulton, C. Mark Moore, and Matthew P. Humphreys
Biogeosciences, 17, 2825–2837,Short summary
The boron isotope pH proxy is increasingly being used to reconstruct ocean pH in the past. Here we detail a novel analytical methodology for measuring the boron isotopic composition (δ11B) of diatom opal and apply this to the study of the diatom Thalassiosira weissflogii grown in culture over a range of pH. To our knowledge this is the first study of its kind and provides unique insights into the way in which diatoms incorporate boron and their potential as archives of palaeoclimate records.
Eleonora Fossile, Maria Pia Nardelli, Arbia Jouini, Bruno Lansard, Antonio Pusceddu, Davide Moccia, Elisabeth Michel, Olivier Péron, Hélène Howa, and Meryem Mojtahid
Biogeosciences, 17, 1933–1953,Short summary
This study focuses on benthic foraminiferal distribution in an Arctic fjord characterised by continuous sea ice production during winter and the consequent cascading of salty and corrosive waters (brine) to the seabed. The inner fjord is dominated by calcareous species (C). In the central deep basins, where brines are persistent, calcareous foraminifera are dissolved and agglutinated (A) dominate. The high A/C ratio is suggested as a proxy for brine persistence and sea ice production.
Johannes Hepp, Imke Kathrin Schäfer, Verena Lanny, Jörg Franke, Marcel Bliedtner, Kazimierz Rozanski, Bruno Glaser, Michael Zech, Timothy Ian Eglinton, and Roland Zech
Biogeosciences, 17, 741–756,
Julian Struck, Marcel Bliedtner, Paul Strobel, Jens Schumacher, Enkhtuya Bazarradnaa, and Roland Zech
Biogeosciences, 17, 567–580,Short summary
We present leaf wax n-alkanes and their compound-specific (CS) δ13C isotopes from semi-arid and/or arid Mongolia to test their potential for paleoenvironmental reconstructions. Plants and topsoils were analysed and checked for climatic control. Chain-length variations are distinct between grasses and Caragana, which are not biased by climate. However CS δ13C is strongly correlated to climate, so n-alkanes and their CS δ13C show great potential for paleoenvironmental reconstruction in Mongolia.
Elena Lo Giudice Cappelli, Jessica Louise Clarke, Craig Smeaton, Keith Davidson, and William Edward Newns Austin
Biogeosciences, 16, 4183–4199,Short summary
Fjords are known sinks of organic carbon (OC); however, little is known about the long-term fate of the OC stored in these sediments. The reason for this knowledge gap is the post-depositional degradation of OC. This study uses benthic foraminifera (microorganisms with calcite shells) to discriminate between post-depositional OC degradation and actual OC burial and accumulation in fjordic sediments, as foraminifera would only preserve the latter information in their assemblage composition.
Sara K. E. Goulden, Naohiko Ohkouchi, Katherine H. Freeman, Yoshito Chikaraishi, Nanako O. Ogawa, Hisami Suga, Oliver Chadwick, and Benjamin Z. Houlton
Biogeosciences, 16, 3869–3882,Short summary
We investigate whether soil organic compounds preserve information about nitrogen availability to plants. We isolate chlorophyll degradation products in leaves, litter, and soil and explore possible species and climate effects on preservation and interpretation. We find that compound-specific nitrogen isotope measurements in soil have potential as a new tool to reconstruct changes in nitrogen cycling on a landscape over time, avoiding issues that have limited other proxies.
Nicolai Schleinkofer, Jacek Raddatz, André Freiwald, David Evans, Lydia Beuck, Andres Rüggeberg, and Volker Liebetrau
Biogeosciences, 16, 3565–3582,Short summary
In this study we tried to correlate Na / Ca ratios from cold-water corals with environmental parameters such as salinity, temperature and pH. We do not observe a correlation between Na / Ca ratios and seawater salinity, but we do observe a strong correlation with temperature. Na / Ca data from warm-water corals (Porites spp.) and bivalves (Mytilus edulis) support this correlation, indicating that similar controls on the incorporation of sodium exist in these aragonitic organisms.
Mattia Greco, Lukas Jonkers, Kerstin Kretschmer, Jelle Bijma, and Michal Kucera
Biogeosciences, 16, 3425–3437,Short summary
To be able to interpret the paleoecological signal contained in N. pachyderma's shells, its habitat depth must be known. Our investigation on 104 density profiles of this species from the Arctic and North Atlantic shows that specimens reside closer to the surface when sea-ice and/or surface chlorophyll concentrations are high. This is in contrast with previous investigations that pointed at the position of the deep chlorophyll maximum as the main driver of N. pachyderma vertical distribution.
Anna Mikis, Katharine R. Hendry, Jennifer Pike, Daniela N. Schmidt, Kirsty M. Edgar, Victoria Peck, Frank J. C. Peeters, Melanie J. Leng, Michael P. Meredith, Chloe L. Todd, Sharon Stammerjohn, and Hugh Ducklow
Biogeosciences, 16, 3267–3282,Short summary
Antarctic marine calcifying organisms are threatened by regional climate change and ocean acidification. Future projections of regional carbonate production are challenging due to the lack of historical data combined with complex climate variability. We present a 6-year record of flux, morphology and geochemistry of an Antarctic planktonic foraminifera, which shows that their growth is most sensitive to sea ice dynamics and is linked with the El Niño–Southern Oscillation.
Eunmi Park, Jens Hefter, Gerhard Fischer, Morten Hvitfeldt Iversen, Simon Ramondenc, Eva-Maria Nöthig, and Gesine Mollenhauer
Biogeosciences, 16, 2247–2268,Short summary
We analyzed GDGT-based proxy temperatures in the polar oceans. In the eastern Fram Strait (79° N), the nutrient distribution may determine the depth habit of Thaumarchaeota and thus the proxy temperature. In the Antarctic Polar Front (50° S), the contribution of Euryarchaeota or the nonlinear correlation between the proxy values and temperatures may cause the warm biases of the proxy temperatures relative to SSTs.
Marijke W. de Bar, Jenny E. Ullgren, Robert C. Thunnell, Stuart G. Wakeham, Geert-Jan A. Brummer, Jan-Berend W. Stuut, Jaap S. Sinninghe Damsté, and Stefan Schouten
Biogeosciences, 16, 1705–1727,Short summary
We analyzed sediment traps from the Cariaco Basin, the tropical Atlantic and the Mozambique Channel to evaluate seasonal imprints in the concentrations and fluxes of long-chain diols (LDIs), in addition to the long-chain diol index proxy (sea surface temperature proxy) and the diol index (upwelling indicator). Despite significant degradation, LDI-derived temperatures were very similar for the sediment traps and seafloor sediments, and corresponded to annual mean sea surface temperatures.
Jens Zinke, Juan P. D'Olivo, Christoph J. Gey, Malcolm T. McCulloch, J. Henrich Bruggemann, Janice M. Lough, and Mireille M. M. Guillaume
Biogeosciences, 16, 695–712,Short summary
Here we report seasonally resolved sea surface temperature (SST) reconstructions for the southern Mozambique Channel in the SW Indian Ocean, a region located along the thermohaline ocean surface circulation route, based on multi-trace-element temperature proxy records preserved in two Porites sp. coral cores for the past 42 years. Particularly, we show the suitability of both separate and combined Sr / Ca and Li / Mg proxies for improved multielement SST reconstructions.
Hilde Pracht, Brett Metcalfe, and Frank J. C. Peeters
Biogeosciences, 16, 643–661,Short summary
In palaeoceanography the shells of single-celled foraminifera are routinely used as proxies to reconstruct the temperature, salinity and circulation of the ocean in the past. Traditionally a number of specimens were pooled for a single stable isotope measurement; however, technical advances now mean that a single shell or chamber of a shell can be measured individually. Three different hypotheses regarding foraminiferal biology and ecology were tested using this approach.
Anna Jentzen, Dirk Nürnberg, Ed C. Hathorne, and Joachim Schönfeld
Biogeosciences, 15, 7077–7095,
Shauna Ní Fhlaithearta, Christophe Fontanier, Frans Jorissen, Aurélia Mouret, Adriana Dueñas-Bohórquez, Pierre Anschutz, Mattias B. Fricker, Detlef Günther, Gert J. de Lange, and Gert-Jan Reichart
Biogeosciences, 15, 6315–6328,Short summary
This study looks at how foraminifera interact with their geochemical environment in the seabed. We focus on the incorporation of the trace metal manganese (Mn), with the aim of developing a tool to reconstruct past pore water profiles. Manganese concentrations in foraminifera are investigated relative to their ecological preferences and geochemical environment. This study demonstrates that Mn in foraminiferal tests is a promising tool to reconstruct oxygen conditions in the seabed.
Siobhan Williams, Walter Adey, Jochen Halfar, Andreas Kronz, Patrick Gagnon, David Bélanger, and Merinda Nash
Biogeosciences, 15, 5745–5759,
Robert Frei, Cora Paulukat, Sylvie Bruggmann, and Robert M. Klaebe
Biogeosciences, 15, 4905–4922,Short summary
The reconstruction of paleo-redox conditions of seawater has the potential to link to climatic changes on land and therefore to contribute to our understanding of past climate change. The redox-sensitive chromium isotope system is applied to marine calcifiers in order to characterize isotope offsets that result from vital processes during calcification processes and which can be eventually used in fossil equivalents to reconstruct past seawater compositions.
Thomas M. DeCarlo, Michael Holcomb, and Malcolm T. McCulloch
Biogeosciences, 15, 2819–2834,Short summary
Understanding the mechanisms of coral calcification is limited by the isolation of the calcifying environment. The boron systematics (B / Ca and δ11B) of aragonite have recently been developed as a proxy for the carbonate chemistry of the calcifying fluid, but a variety of approaches have been utilized. We assess the available experimental B / Ca partitioning data and present a computer code for deriving calcifying fluid carbonate chemistry from the boron systematics of coral skeletons.
Manuel Bringué, Robert C. Thunell, Vera Pospelova, James L. Pinckney, Oscar E. Romero, and Eric J. Tappa
Biogeosciences, 15, 2325–2348,Short summary
We document 2.5 yr of dinoflagellate cyst production in the Cariaco Basin using a sediment trap record. Each species' production pattern is interpreted in the context of the physico-chemical (e.g., temperature, nutrients) and biological (other planktonic groups) environment. Most species respond positively to upwelling, but seem to be negatively impacted by an El Niño event with a 1-year lag. This work helps understanding dinoflagellate ecology and interpreting fossil assemblages in sediments.
Gabriella M. Weiss, Eva Y. Pfannerstill, Stefan Schouten, Jaap S. Sinninghe Damsté, and Marcel T. J. van der Meer
Biogeosciences, 14, 5693–5704,Short summary
Algal-derived compounds allow us to make assumptions about environmental conditions in the past. In order to better understand how organisms record environmental conditions, we grew microscopic marine algae at different light intensities, salinities, and alkalinities in a temperature-controlled environment. We determined how these environmental parameters affected specific algal-derived compounds, especially their relative deuterium content, which seems to be mainly affected by salinity.
S. Nemiah Ladd, Nathalie Dubois, and Carsten J. Schubert
Biogeosciences, 14, 3979–3994,Short summary
Hydrogen isotopes of lipids provide valuable information about microbial activity, climate, and environmental stress. We show that heavy hydrogen in fatty acids declines from spring to summer in a nutrient-rich and a nutrient-poor lake and that the effect is nearly 3 times as big in the former. This effect is likely a combination of increased biomass from algae, warmer temperatures, and higher algal growth rates.
Karoliina A. Koho, Lennart J. de Nooijer, Christophe Fontanier, Takashi Toyofuku, Kazumasa Oguri, Hiroshi Kitazato, and Gert-Jan Reichart
Biogeosciences, 14, 3067–3082,Short summary
Here we report Mn / Ca ratios in living benthic foraminifera from the NE Japan margin. The results show that the Mn incorporation directly reflects the environment where the foraminifera calcify. Foraminifera that live deeper in sediment, under greater redox stress, generally incorporate more Mn into their carbonate skeletons. As such, foraminifera living close to the Mn reduction zone in sediment appear promising tools for paleoceanographic reconstructions of sedimentary redox conditions.
Stefania Milano, Gernot Nehrke, Alan D. Wanamaker Jr., Irene Ballesta-Artero, Thomas Brey, and Bernd R. Schöne
Biogeosciences, 14, 1577–1591,
Diana Zúñiga, Celia Santos, María Froján, Emilia Salgueiro, Marta M. Rufino, Francisco De la Granda, Francisco G. Figueiras, Carmen G. Castro, and Fátima Abrantes
Biogeosciences, 14, 1165–1179,Short summary
Diatoms are one of the most important primary producers in highly productive coastal regions. Their silicified valves are susceptible to escape from the upper water column and be preserved in the sediment record, and thus are frequently used to reconstruct environmental conditions in the past from sediment cores. Here, we assess how water column diatom’s community in the NW Iberian coastal upwelling system is seasonally transferred from the surface to the seafloor sediments.
Andreia Rebotim, Antje H. L. Voelker, Lukas Jonkers, Joanna J. Waniek, Helge Meggers, Ralf Schiebel, Igaratza Fraile, Michael Schulz, and Michal Kucera
Biogeosciences, 14, 827–859,Short summary
Planktonic foraminifera species depth habitat remains poorly constrained and the existing conceptual models are not sufficiently tested by observational data. Here we present a synthesis of living planktonic foraminifera abundance data in the subtropical eastern North Atlantic from vertical plankton tows. We also test potential environmental factors influencing the species depth habitat and investigate yearly or lunar migration cycles. These findings may impact paleoceanographic studies.
Clemens Vinzenz Ullmann and Philip A. E. Pogge von Strandmann
Biogeosciences, 14, 89–97,Short summary
This study documents how much control growth rate has on the chemical composition of fossil shell material. Using a series of chemical analyses of the fossil hard part of a belemnite, an extinct marine predator, a clear connection between the rate of calcite formation and its magnesium and strontium contents was found. These findings provide further insight into biomineralization processes and help better understand chemical signatures of fossils as proxies for palaeoenvironmental conditions.
Justine Kimball, Robert Eagle, and Robert Dunbar
Biogeosciences, 13, 6487–6505,Short summary
Deep-sea corals are a potentially valuable archive of temperature and ocean chemistry. We analyzed clumped isotope signatures (Δ47) in live-collected aragonitic scleractinian and high-Mg calcitic gorgonian deep-sea corals and compared results to published data and found offsets between taxa. The observed patterns in deep-sea corals may record distinct mineral equilibrium signatures due to very slow growth rates, kinetic isotope effects, and/or variable acid digestion fractionation factors.
Lisa Warden, Jung-Hyun Kim, Claudia Zell, Geert-Jan Vis, Henko de Stigter, Jérôme Bonnin, and Jaap S. Sinninghe Damsté
Biogeosciences, 13, 5719–5738,Short summary
Enhanced analytical techniques were applied to characterize fossilized microbial cell membrane lipids from samples in the Tagus River basin spanning the last 6000 years. Using the novel methods and calibration, the pH estimates were improved upon, and this study reveals new factors that should be considered when using this proxy as well as affirms the importance of examining the provenance of these lipids before applying them for paleoclimate reconstructions.
A. Ponnurangam, M. Bau, M. Brenner, and A. Koschinsky
Biogeosciences, 13, 751–760,Short summary
Our study demonstrates that rare earth elements and yttrium (REY) accumulating in mussel shells emerge as potential proxies for environmental changes. Focusing on pH and temperature variation effects on the distribution of REY in seawater, we show that shells incorporate the free REY3+ species and that decreasing pH leads to increased REY concentrations, while rising temperatures impact the REY distribution pattern with minor effects on the absolute REY concentrations in shells.
O. T. Moldovan, S. Constantin, C. Panaiotu, R. D. Roban, P. Frenzel, and L. Miko
Biogeosciences, 13, 483–497,Short summary
The paper presents the results of a fossil invertebrates study in four caves of the Romanian Carpathians, to complement paleoenvironmental data previously reported. Oribatid mites and ostracods are the most common invertebrates in the studied cave sediments. By corroborating the fossil invertebrates' record with the information given by magnetic properties and sediment structures, complementary data on past vegetation, temperatures, and hydraulic regimes could be gathered.
C. Häggi, C. M. Chiessi, and E. Schefuß
Biogeosciences, 12, 7239–7249,
J. M. Bernhard, W. G. Phalen, A. McIntyre-Wressnig, F. Mezzo, J. C. Wit, M. Jeglinski, and H. L. Filipsson
Biogeosciences, 12, 5515–5522,Short summary
We present an innovative method using osmotic pumps and the fluorescent marker calcein to help identify where and when calcareous bottom-dwelling organisms mineralize in sediments. These organisms, and their geochemical signatures in their carbonate, are the ocean’s storytellers helping us understand past marine conditions. For many species, the timing and location of their calcite growth is not known. Knowing this will enable us to reconstruct past marine environments with greater accuracy.
C. L. McKay, J. Groeneveld, H. L. Filipsson, D. Gallego-Torres, M. J. Whitehouse, T. Toyofuku, and O.E. Romero
Biogeosciences, 12, 5415–5428,Short summary
We highlight the proxy potential of foraminiferal Mn/Ca determined by secondary ion mass spectrometry and flow-through inductively coupled plasma optical emission spectroscopy for recording changes in bottom-water oxygen conditions. Comparisons with Mn sediment bulk measurements from the same sediment core largely agree with the results. High foraminiferal Mn/Ca occurs in samples from times of high productivity export and corresponds with the benthic foraminiferal faunal composition.
J. Schilder, C. Tellenbach, M. Möst, P. Spaak, M. van Hardenbroek, M. J. Wooller, and O. Heiri
Biogeosciences, 12, 3819–3830,Short summary
We show that the stable (C, N, O) isotopic composition of the water flea Daphnia pulicaria is strongly related to that of its diet (C, N) and the water they live in (O). We also show that the stable isotopic composition of the sheaths of Daphnia resting eggs (ephippia) is indicative of the isotopic composition of Daphnia that produced them. This implies that stable isotope ratios of fossil Daphnia ephippia can provide information on past ecological and climatic developments in and around lakes.
W. Clymans, L. Barão, N. Van der Putten, S. Wastegård, G. Gísladóttir, S. Björck, B. Moine, E. Struyf, and D. J. Conley
Biogeosciences, 12, 3789–3804,Short summary
Biogenic silica (BSi) is used as a proxy by soil scientists to identify biological effects on the Si cycle and by palaeoecologists to study environmental changes. We show the presence of tephra constituents can make measurements erroneous at low BSi concentrations, with repercussions for soil and palaeoecological studies. However, we also show that glass shards do not produce an identical dissolution signal to that of BSi, meaning they can be distinguished with appropriate experimental setups.
T. Bauersachs, J. Rochelmeier, and L. Schwark
Biogeosciences, 12, 3741–3751,
K. R. Hendry, G. E. A. Swann, M. J. Leng, H. J. Sloane, C. Goodwin, J. Berman, and M. Maldonado
Biogeosciences, 12, 3489–3498,Short summary
The stable isotope composition of benthic sponge silica skeletons (spicules) has been shown to be a source of useful palaeoceanographic information about past deep seawater chemistry. Here, we investigate the biological vital effects on silica stable isotope composition in a Southern Ocean carnivorous sponge, Asbestopluma sp. We find significant variations in isotopic composition within the specimen – in both silicon and oxygen isotopes – that appear to be related to unusual spicule growth.
Y.-W. Liu, S. M. Aciego, and A. D. Wanamaker Jr.
Biogeosciences, 12, 3351–3368,Short summary
We report the first high-resolution strontium (87Sr/86Sr and δ88/86Sr) and boron (δ11B) isotopic values in the aragonite shell of cultured Arctica islandica. These results suggest that well-preserved subfossil specimens may be used to determine the past Sr isotopic composition of seawater. The δ11B in this experiment suggests that the boron uptake of the shell changes at a temperature threshold of 13°C and a species-specific fractionation factor may be required for seawater pH reconstructions.
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K. Kaczmarek, G. Langer, G. Nehrke, I. Horn, S. Misra, M. Janse, and J. Bijma
Biogeosciences, 12, 1753–1763,Short summary
Culture experiments based on a decoupled pH and CO32- chemistry indicate that the δ11B of the test of A. lessonii is related to pH whereas the B/Ca of the foraminiferal shells show a positive correlation with B(OH)4-/HCO3-. The latter observation suggests a competition between B(OH)4- and HCO3- of the culture media for B uptake into the test.
T. Pados, R. F. Spielhagen, D. Bauch, H. Meyer, and M. Segl
Biogeosciences, 12, 1733–1752,Short summary
Fossil planktic foraminifera and their geochemical composition are commonly used proxies in palaeoceanography. Our study with living specimens revealed that in the Fram Strait both Neogloboquadrina pachyderma and Turborotalita quinqueloba from the water column have lower δ18O and δ13C values than inorganically precipitated calcite/fossil tests from the sediment surface. These offsets indicate biological influence during calcification and a change of water column properties in the recent past.
K. H. Salmon, P. Anand, P. F. Sexton, and M. Conte
Biogeosciences, 12, 223–235,Short summary
Planktonic foraminifera are an important component of the marine carbon/carbonate cycle, yet the environmental controls on their abundances are still debated. In our study, we see larger foraminifera fluxes, particularly of heavy species, during winter when nutrients are mixed into the surface waters or during eddy mixing. Climatic factors that control mixing could therefore control the flux of planktonic foraminfera and the carbon/carbonate flux on seasonal and decadal timescales.
N. Glock, V. Liebetrau, and A. Eisenhauer
Biogeosciences, 11, 7077–7095,Short summary
Our study explores the correlation of I/Ca ratios in four benthic foraminiferal species (three calcitic, one aragonitic) from the Peruvian OMZ with bottom water oxygenation ([O2]BW), and evaluates foraminiferal I/Ca ratios as a possible redox proxy. All species have a positive trend in the I/Ca ratios as a function of [O2]BW. Only for the aragonitic species Hoeglundina elegans is this trend not significant. The highest significance has been found for Uvigerina striata.
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The relationships between environmental variables and the cyclization of branched tetraethers (CBT) were investigated in surface soils in the Chinese Loess Plateau (CLP) and its vicinity. We find that CBT is not sensitive to soil pH but correlates best with soil moisture in these alkaline soils from arid-subhumid regions. Therefore, we suggest that CBT can potentially be used as a palaeorainfall proxy on the CLP and applied it to three loess-paleosol sequences published before.
The relationships between environmental variables and the cyclization of branched tetraethers...