Mg/Ca ratios in stressed foraminifera, Amphistegina gibbosa, from the Florida Keys

Toler, Strawn K.; Hallock, Pamela; Schijf, Johan

doi:10.1016/s0377-8398(01)00034-2

Cited by 33 publications

(17 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The coral Mg/Ca ratios (mmol/mol) reported range from 3.896 to 5.138 (mean 4.628) for coral in Sanya Bay [23] and from 3.18 to 4.61 (mean 3.83) in the Caribbean Sea [24] . Meanwhile, the Mg/Ca ratios (mmol/mol) reported by Toler et al [25] show the higher values of 20-40 (mean 30) in gibbosa specimens (foraminiferal) and 100-150 (mean 120) in high Mg-calcite of A. angulatus (foraminferal), which is compared with the result for using seawater as a parent solution in this study. Lea et al [22] indicate temperature is primary control on foraminifara shell Mg/Ca and seawater pH is secondary influences on shell Mg/Ca and shell Mg/Ca decreases by 6% per 0.1 pH unit increase for seawater pH varying from 7.6 to 8.5, which is inconsistent with the observation in this study that Mg/Ca ratios in SCCP increase with the increase of pH values.…”

Section: Magnesium Concentration Of Calcium Carbonate Precipitation (supporting

confidence: 69%

“…A local high pH value (>9) of system solution enough to form Mg(OH) 2 should present when the drop of NaOH solution was added, but this status is infrequent, but is not absolutely impossible, for the calcification of biological carbonates. Scoffin [32] , as cited by Toler et al [25] , reported that high-magnesium calcite can contain more than 5% MgCO 3 , which implies that MgCO 3 may precipitate with CaCO 3 . In this study, the XRD of MgCO 3 in XRD curve of SCCP is not detected when comparing Figs.…”

Section: Magnesium Concentration Of Calcium Carbonate Precipitation (mentioning

confidence: 99%

See 1 more Smart Citation

An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water

Wei

Sun

et al. 2006

SCI CHINA SER B

View full text Add to dashboard Cite

Inorganic calcium carbonate precipitation from natural seawater and saline water at various pH values was carried out experimentally. The results show the clear positive relationships between boron concentration and δ 11 B of inorganic calcium carbonate with the pH of natural seawater and saline water. However, the variations of boron isotopic fractionation between inorganic calcite and seawater/saline water with pH are inconsistent with the hypothesis that B(OH) 4 − is the dominant species incorporated into the biogenic calcite structure. The isotopic fractionation factors α between synthetic calcium carbonate precipitate and parent solutions increase systematically as pH increases, from 0.9884 at pH 7.60 to 1.0072 at pH 8.60 for seawater and from 0.9826 at pH 7.60 to 1.0178 at pH 8.75 for saline water. An unusual boron isotopic fractionation factor of larger than 1 in synthetic calcium carbonate precipitated from seawater/saline water at higher pH is observed, which implies that a substantial amount of the isotopically heavier B(OH) 3 species must be incorporated preferentially into synthetic inorganic carbonate. The results propose that the incorporation of B(OH) 3 is attributed to the formation of Mg(OH) 2 at higher pH of calcifying microenvironment during the synthetic calcium carbonate precipitation. The preliminary experiment of Mg(OH) 2 precipitated from artificial seawater shows that heavier 11 B is enriched in Mg(OH) 2 precipitation, which suggests that isotopically heavier B(OH) 3 species incorporated preferentially into Mg(O This result cannot be applied to explain the boron isotopic fractionation of marine bio-carbonate because of the possibility that the unusual environment in this study appears in formation of marine bio-carbonate is infinitesimal. We, however, must pay more attention to this phenomenon observed in this study, which accidentally appears in especially natural environment.Keywords: boron, isotopic fractionation, calcium carbonate precipitate, seawater, saline water.Many investigations focused on boron incorporation into marine organisms by co-precipitation with biogenic carbonate minerals, attempting to reconstruct the past oceanic pH using the isotopic composition of boron in coral and foraminifera [1][2][3][4][5][6][7][8][9][10] . Spivack et al. [3] reported that 21 Ma ago, the surface ocean pH was only 7.4 ± 0.2, which then increased to 8.2 ± 0.2 about 7.5 Ma ago. Sanyal et al. [5] estimated that the deep An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater & saline water 455 Atlantic and Pacific oceans had a pH 0.3±0.1 unit higher during the last glaciation. Pearson and Palmer [9] found that the pH was significantly lower during early Palaeogene than in the Neogene period. The application of boron isotope studies in marine biogenic carbonate to the reconstruction of paleo-pH of seawater relies on three hypotheses as follows: (i) A large isotopic fractionation between the two aqueous species, B(OH) 3 and B(OH) 4 − of boron in seawate...

show abstract

Section: Magnesium Concentration Of Calcium Carbonate Precipitation (supporting

confidence: 69%

Section: Magnesium Concentration Of Calcium Carbonate Precipitation (mentioning

confidence: 99%

An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water

Wei

Sun

et al. 2006

SCI CHINA SER B

View full text Add to dashboard Cite

show abstract

“…10c). Since Mg/Ca molar ratio of benthic foraminifera is normally assumed to be between 0.0005 and 0.01 mol mol −1 (Lea, 1999;Toler et al, 2001;Toyofuku and Kitazato, 2005), we propose that conditions of environmental stress may influence the amount of Mg incorporated during the foraminifera's growth. Our results are in agreement with the experimental investigation on Mg intrashell reactions of Bentov and Erez (2005) and which are attributed to a kinetic mechanism played by the carbonate ions in the calcite growth by Lopez et al (2009).…”

Section: Environmental Conditions and Bioerosionmentioning

confidence: 99%

Bioerosion by microbial euendoliths in benthic foraminifera from heavy metal-polluted coastal environments of Portovesme (south-western Sardinia, Italy)

et al. 2012

View full text Add to dashboard Cite

Abstract.A monitoring survey of the coastal area facing the industrial area of Portoscuso-Portovesme (south-western Sardinia, Italy) revealed intense bioerosional processes. Benthic foraminifera collected at the same depth (about 2 m) but at different distances from the pollution source show extensive microbial infestation, anomalous Mg/Ca molar ratios and high levels of heavy metals in the shell associated with a decrease in foraminifera richness, population density and biodiversity with the presence of morphologically abnormal specimens. We found that carbonate dissolution induced by euendoliths is selective, depending on the Mg content and morpho-structural types of foraminiferal taxa. This study provides evidences for a connection between heavy metal dispersion, decrease in pH of the sea-water and bioerosional processes on foraminifera.

show abstract

“…Both these factors play a role in its reactivity (Stumm, 1992). Toler et al (2001) advanced the possibility that an increase in Mg/Ca ratio promotes tests damage. Therefore, differences in magnesium content make calcite tests behave differently in systems close to saturation.…”

Section: Discussionmentioning

confidence: 99%

“…Those features are related to evolution, and also to environmental factors such as climate, salinity, vegetation, hydrochemistry and even pollution conditions (Murray, 1973;Alve & Nagy, 1986;Sen Gupta, 1999;Geslin et al, 2000;Toler et al, 2001;Debeney et al, 2002;Le Cadre et al, 2003). Among these, the geochemical parameters of the carbonate equilibrium solution are of major significance.…”

Section: Introductionmentioning

confidence: 99%

Occurrence of calcareous foraminifera and calcite-carbonate equilibrium conditions – a case study in Minho/Coura estuary (Northern Portugal)

et al. 2007

View full text Add to dashboard Cite

The Minho/Coura estuary, northern Portugal, has been studied for the influence of hydrochemical and geochemical parameters on living (Rose Bengal stained) foraminiferal assemblages. Our previous works showed a prevalence of agglutinated species in the inner estuary and tidal marsh and significant abundance of calcareous species only in the estuary mouth. The new results clarify syndepositional aspects of the calcareous species related to calcite dissolution, such as thin tests that frequently lack the carbonate layer and show typical destruction features. Sites from the estuary mouth, tidal marsh and river were sampled, under Spring and Autumn conditions, in order to describe physical-chemical features and to allow the geochemical modelling of the solution in which calcification occurs. In particular, the chemical equilibrium regarding calcite was evaluated from the saturation index (SI). Such modelling suggests strongly undersaturated conditions at the majority of the sampling sites, in both sampling periods. The water quality data revealed strong spatial and temporal variability, mainly in the tidal marsh environment, and also the existence of a stressed medium regarding calcite saturation state. The observed geochemical trends provide a plausible explanation for (1) the scarcity and distribution of living calcareous foraminifera in the Minho/ Coura estuary and (2) the destruction features observed in the carbonate tests.

show abstract

Mg/Ca ratios in stressed foraminifera, Amphistegina gibbosa, from the Florida Keys

Cited by 33 publications

References 15 publications

An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water

An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water

Bioerosion by microbial euendoliths in benthic foraminifera from heavy metal-polluted coastal environments of Portovesme (south-western Sardinia, Italy)

Occurrence of calcareous foraminifera and calcite-carbonate equilibrium conditions – a case study in Minho/Coura estuary (Northern Portugal)

Contact Info

Product

Resources

About