scholarly journals Incorporation of uranium in benthic foraminiferal calcite reflects seawater carbonate ion concentration

2013 ◽  
Vol 14 (1) ◽  
pp. 102-111 ◽  
Author(s):  
Nina Keul ◽  
Gerald Langer ◽  
Lennart Jan Nooijer ◽  
Gernot Nehrke ◽  
Gert‐Jan Reichart ◽  
...  
Keyword(s):  
Ion Concentration ◽  
Carbonate Ion

scholarly journals Current CaCO3 dissolution at the seafloor caused by anthropogenic CO2

2018 ◽  
Vol 115 (46) ◽  
pp. 11700-11705 ◽  
Author(s):  
Olivier Sulpis ◽  
Bernard P. Boudreau ◽  
Alfonso Mucci ◽  
Chris Jenkins ◽  
David S. Trossman ◽  
...  
Keyword(s):  
North Atlantic ◽  
Deep Sea ◽  
Hot Spots ◽  
Ion Concentration ◽  
Rate Model ◽  
Saturation State ◽  
Calcite Dissolution ◽  
Carbonate Ion ◽  
Anthropogenic Component ◽  
Compensation Depth

Oceanic uptake of anthropogenic CO2 leads to decreased pH, carbonate ion concentration, and saturation state with respect to CaCO3 minerals, causing increased dissolution of these minerals at the deep seafloor. This additional dissolution will figure prominently in the neutralization of man-made CO2. However, there has been no concerted assessment of the current extent of anthropogenic CaCO3 dissolution at the deep seafloor. Here, recent databases of bottom-water chemistry, benthic currents, and CaCO3 content of deep-sea sediments are combined with a rate model to derive the global distribution of benthic calcite dissolution rates and obtain primary confirmation of an anthropogenic component. By comparing preindustrial with present-day rates, we determine that significant anthropogenic dissolution now occurs in the western North Atlantic, amounting to 40–100% of the total seafloor dissolution at its most intense locations. At these locations, the calcite compensation depth has risen ∼300 m. Increased benthic dissolution was also revealed at various hot spots in the southern extent of the Atlantic, Indian, and Pacific Oceans. Our findings place constraints on future predictions of ocean acidification, are consequential to the fate of benthic calcifiers, and indicate that a by-product of human activities is currently altering the geological record of the deep sea.

scholarly journals Environmental controls on the <i>Emiliania huxleyi</i> calcite mass

2014 ◽  
Vol 11 (8) ◽  
pp. 2295-2308 ◽  
Author(s):  
M. T. Horigome ◽  
P. Ziveri ◽  
M. Grelaud ◽  
K.-H. Baumann ◽  
G. Marino ◽  
...  
Keyword(s):  
Seawater Temperature ◽  
World Ocean ◽  
Environmental Parameters ◽  
Abundant Species ◽  
Emiliania Huxleyi ◽  
Ion Concentration ◽  
Carbonate Chemistry ◽  
Environmental Controls ◽  
Carbonate Ion ◽  
Phosphate Availability

Abstract. Although ocean acidification is expected to impact (bio) calcification by decreasing the seawater carbonate ion concentration, [CO32−], there is evidence of nonuniform response of marine calcifying plankton to low seawater [CO32−]. This raises questions about the role of environmental factors other than acidification and about the complex physiological responses behind calcification. Here we investigate the synergistic effect of multiple environmental parameters, including seawater temperature, nutrient (nitrate and phosphate) availability, and carbonate chemistry on the coccolith calcite mass of the cosmopolitan coccolithophore Emiliania huxleyi, the most abundant species in the world ocean. We use a suite of surface (late Holocene) sediment samples from the South Atlantic and southwestern Indian Ocean taken from depths lying above the modern lysocline (with the exception of eight samples that are located at or below the lysocline). The coccolith calcite mass in our results presents a latitudinal distribution pattern that mimics the main oceanographic features, thereby pointing to the potential importance of seawater nutrient availability (phosphate and nitrate) and carbonate chemistry (pH and pCO2) in determining coccolith mass by affecting primary calcification and/or the geographic distribution of E. huxleyi morphotypes. Our study highlights the importance of evaluating the combined effect of several environmental stressors on calcifying organisms to project their physiological response(s) in a high-CO2 world and improve interpretation of paleorecords.

The coral reef-dwelling Peneroplis spp. shows calcification resilience to ocean acidification conditions - results from culture experiments

2021 ◽  
Author(s):  
Laurie Charrieau ◽  
Katsunori Kimoto ◽  
Delphine Dissard ◽  
Beatrice Below ◽  
Kazuhiko Fujita ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Ocean Acidification ◽  
Sea Water ◽  
General Structure ◽  
Ion Concentration ◽  
Large Benthic Foraminifera ◽  
Carbonate Ion ◽  
Short Period

&lt;p&gt;Ocean acidification is a consequence of current anthropogenic climate changes.&amp;#160;The concomitant decrease in pH and carbonate ion concentration in sea water may have severe impacts on calcifying organisms. Coral reefs are among the first ecosystems recognized vulnerable to ocean acidification. Within&amp;#160;coral reefs, large benthic foraminifera (LBF) are major calcium carbonate producers.&lt;/p&gt;&lt;p&gt;The aim of this study was to evaluate the effects of varying&amp;#160;pH on&amp;#160;survival and calcification of the&amp;#160;symbiont-bearing LBF species &lt;em&gt;Peneroplis&lt;/em&gt; spp.&amp;#160;We performed culture experiments to study their&amp;#160;resistance to ocean acidification conditions,&amp;#160;as well as their resilience once placed back under open ocean pH (7.9).&lt;/p&gt;&lt;p&gt;After three&amp;#160;days, small signs of test decalcification were observed on specimens kept at pH 7.4, and severe test decalcification was observed on specimens kept at pH 6.9, with the inner organic lining clearly appearing.&amp;#160;After 32 days under pH 7.4, similar strongly decalcified specimens were observed. All the specimens were alive&amp;#160;at the end of the experiment. This result demonstrates the&amp;#160;resistance of &lt;em&gt;Peneroplis &lt;/em&gt;spp.&amp;#160;to an acidified pH, at least on a short period of time.&lt;/p&gt;&lt;p&gt;After being partially decalcified, some of the living specimens were placed back at pH 7.9. After one month, the majority of the specimens showed recalcification&amp;#160;features, mostly by addition of new chambers.&amp;#160;The trace elements concentrations of the newly formed chambers were analysed by LA-ICPMS. Interestingly, more chambers were added when food was given, which&amp;#160;highlights the crucial role of energy source in the&amp;#160;recalcification process. Moreover, the newly formed chambers were most of the time abnormal, and the general structure&amp;#160;of the tests was altered, with potential impacts on reproduction and in situ survival. In conclusion, if symbiont-bearing LBF show some resistance and resilience to&amp;#160;lowered pH&amp;#160;conditions, they&amp;#160;will remain&amp;#160;strongly affected by ocean acidification.&lt;/p&gt;

scholarly journals Coupled calcium and inorganic carbon uptake suggested by magnesium and sulfur incorporation in foraminiferal calcite

2019 ◽  
Vol 16 (10) ◽  
pp. 2115-2130 ◽  
Author(s):  
Inge van Dijk ◽  
Christine Barras ◽  
Lennart Jan de Nooijer ◽  
Aurélia Mouret ◽  
Esmee Geerken ◽  
...  
Keyword(s):  
Crystal Lattice ◽  
Multiple Scales ◽  
Proton Pumping ◽  
Ion Concentration ◽  
Carbon Uptake ◽  
Uptake Mechanism ◽  
Carbonate Ion ◽  
Shell Chemistry ◽  
Influence Of Temperature On ◽  
Element Speciation

Abstract. Shell chemistry of foraminiferal carbonate proves to be useful in reconstructing past ocean conditions. A new addition to the proxy toolbox is the ratio of sulfur (S) to calcium (Ca) in foraminiferal shells, reflecting the ratio of SO42- to CO32- in seawater. When comparing species, the amount of SO42- incorporated, and therefore the S∕Ca of the shell, increases with increasing magnesium (Mg) content. The uptake of SO42- in foraminiferal calcite is likely connected to carbon uptake, while the incorporation of Mg is more likely related to Ca uptake since this element substitutes for Ca in the crystal lattice. The relation between S and Mg incorporation in foraminiferal calcite therefore offers the opportunity to investigate the timing of processes involved in Ca and carbon uptake. To understand how foraminiferal S∕Ca is related to Mg∕Ca, we analyzed the concentration and within-shell distribution of S∕Ca of three benthic species with different shell chemistry: Ammonia tepida, Bulimina marginata and Amphistegina lessonii. Furthermore, we investigated the link between Mg∕Ca and S∕Ca across species and the potential influence of temperature on foraminiferal S∕Ca. We observed that S∕Ca is positively correlated with Mg∕Ca on a microscale within specimens, as well as between and within species. In contrast, when shell Mg∕Ca increases with temperature, foraminiferal S∕Ca values remain similar. We evaluate our findings in the light of previously proposed biomineralization models and abiological processes involved during calcite precipitation. Although all kinds of processes, including crystal lattice distortion and element speciation at the site of calcification, may contribute to changes in either the amount of S or Mg that is ultimately incorporated in foraminiferal calcite, these processes do not explain the covariation between Mg∕Ca and S∕Ca values within specimens and between species. We observe that groups of foraminifera with different calcification pathways, e.g., hyaline versus porcelaneous species, show characteristic values for S∕Ca and Mg∕Ca, which might be linked to a different calcium and carbon uptake mechanism in porcelaneous and hyaline foraminifera. Whereas Mg incorporation might be controlled by Ca dilution at the site of calcification due to Ca pumping, S is linked to carbonate ion concentration via proton pumping. The fact that we observe a covariation of S and Mg within specimens and between species suggests that proton pumping and Ca pumping are intrinsically coupled across multiple scales.

scholarly journals Changes in calcification of coccoliths under stable atmospheric CO<sub>2</sub>

2014 ◽  
Vol 11 (4) ◽  
pp. 929-944 ◽  
Author(s):  
C. Berger ◽  
K. J. S. Meier ◽  
H. Kinkel ◽  
K.-H. Baumann
Keyword(s):  
Environmental Factors ◽  
North Atlantic ◽  
Ion Concentration ◽  
Average Weight ◽  
Natural Environments ◽  
Weight Changes ◽  
The Holocene ◽  
The North ◽  
Carbonate Ion ◽  
The North Atlantic

Abstract. The response of coccolithophore calcification to ocean acidification has been studied in culture experiments as well as in present and past oceans. The response, however, is different between species and strains, and for the relatively small carbonate chemistry changes observed in natural environments, a uniform response of the entire coccolithophore community has not been documented so far. Moreover, previous palaeo-studies basically focus on changes in coccolith weight due to increasing CO2 and the resulting changes in the carbonate system, and only few studies focus on the influence of other environmental factors. In order to untangle changes in coccolithophore calcification due to environmental factors such as temperature and/or productivity from changes caused by increasing pCO2 and decreasing carbonate ion concentration, we here present a study on coccolith calcification from the Holocene North Atlantic Ocean. The pre-industrial Holocene, with its predominantly stable atmospheric CO2, provides the conditions for such a comprehensive analysis. For an analysis on changes in major components of Holocene coccolithophores under natural conditions, the family Noelaerhabdaceae was selected, which constitutes the main part of the assemblage in the North Atlantic. Records of average coccolith weights from three Holocene sediment cores along a north–south transect in the North Atlantic were analysed. During the Holocene, mean weight (and therefore calcification) of Noelaerhabdaceae (Emiliania huxleyi and Gephyrocapsa) coccoliths decreased at the Azores (Geofar KF 16) from around 7 to 6 pg, but increased at the Rockall Plateau (ODP site 980) from around 6 to 8 pg, and at the Vøring Plateau (MD08-3192) from 7 to 10 pg. The amplitude of average weight variability is within the range of glacial–interglacial changes that were interpreted to be an effect of decreasing carbonate ion concentration. By comparison with SEM assemblage counts, we show that weight changes are not only partly due to variations in the coccolithophore assemblage but also an effect of a change in calcification and/or morphotype variability within single species. Our results indicate that there is no single key factor responsible for the observed changes in coccolith weight. A major increase in coccolith weight occurs during a slight decrease in carbonate ion concentration in the late Holocene at the Rockall Plateau and Vøring Plateau. Here, more favourable productivity conditions apparently lead to an increase in coccolith weight, either due to the capability of coccolithophore species, especially E. huxleyi, to adapt to decreasing carbonate ion concentration or due to a shift towards heavier calcifying morphotypes.

scholarly journals Ba, B, and U element partitioning in magnesian calcite skeletons of Octocorallia corals

2015 ◽  
Vol 12 (1) ◽  
pp. 413-444 ◽  
Author(s):  
T. Yoshimura ◽  
A. Suzuki ◽  
N. Iwasaki
Keyword(s):  
Carbon Sources ◽  
Deep Ocean ◽  
Ion Concentration ◽  
Dissolved Carbon ◽  
Oxygen And Carbon Isotope ◽  
Carbonate Ion ◽  
Deep Waters ◽  
Element Partitioning ◽  
Physicochemical Factors ◽  
Positive Correlations

Abstract. Barium, boron and uranium element partitioning and oxygen and carbon isotope fractionation of high-Mg calcite skeletons of Octocorallia corals were investigated. The dissolved Ba concentration in seawater and the coral Ba/Ca ratio showed a clear positive correlation. The empirically derived barium partition coefficient is comparable to previous data for not only calcitic corals but also intermediate- to deep-water-dwelling scleractinian corals whose skeletons are composed of aragonite. Octocorallia corals are geologically important producers of biominerals, and they provide long-term records (up to hundreds of years) of environmental conditions in the deep ocean. Our data suggest that Ba/Ca ratios in Octocorallia corals may be a useful proxy for nutrients in intermediate and deep waters. The Ba/Ca ratio, a possible proxy for pH or carbonate ion concentration in seawater, showed the largest correlation with δ13C among the examined parameters. This result implies that the pH of the extracytoplasmic calcifying fluid (ECF) simultaneously influences δ18O, δ13C, and Ba/Ca by influencing the relative contributions of dissolved carbon sources in the ECF. Positive correlations of Ba/Ca with δ18 and δ13C suggest that δ18 and δ13C are enriched in light isotopes when conditions are less alkaline, suggesting a potential role of biological alkalinity pumping becomes more favorable with decreasing calcifying fluid pH. Substantial inter- and intra-specimen variations in Ba/Ca suggest that physicochemical factors do not exert a dominant systematic control on U incorporation.

Effects of seawater carbonate ion concentration and temperature on shell U, Mg, and Sr in cultured planktonic foraminifera

2004 ◽  
Vol 68 (21) ◽  
pp. 4347-4361 ◽  
Author(s):  
Ann D. Russell ◽  
Bärbel Hönisch ◽  
Howard J. Spero ◽  
David W. Lea
Keyword(s):  
Planktonic Foraminifera ◽  
Ion Concentration ◽  
Carbonate Ion
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