Effects of pre-treatment on ostracod valve chemistry

Keatings, K.; Holmes, Jonathan A.; Heaton, T.H.E.

doi:10.1016/j.chemgeo.2006.07.003

Cited by 40 publications

(40 citation statements)

References 25 publications

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“…Considering that chemical and physical pre-analytical treatments are potential sources of alteration of isotopic composition, and that their effects may differ between species, a general recommendation should be to avoid the application of such treatments. This is consistent with recent recommendations for corals (Grottoli et al, 2005), ostracods (Keatings et al, 2006) and a range of carbonates (Wierzbowski, 2007). This study does not provide universal guidelines for all species of foraminifera or for different pre-treatment designs, and further tests should be done to evaluate whether these findings can be generalized.…”

Section: Resultssupporting

confidence: 63%

Effects of sample pre-treatment on the δ13C and δ18O values of living benthic foraminifera

Serrano

Mateo

2008

Chemical Geology

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Stable carbon and oxygen isotope ratios (δ 13 C and δ 18 O) of the epibenthic foraminiferan Elphidium macellum var. aculeatum were measured and compared both in raw aliquots and after various preanalytical treatments. We tested the effects of chemical cleaning procedures (oxygen plasma ashing, NaClO and H 2 O 2 ) and physical (ultrasounds) aimed at removing allochthonous particles.We also assessed the effects of using preservatives (formaldehyde and ethanol) and stains (Bengal Rose and Sudan Black B) prior to δ 13 C and δ 18 O analyses. Although the effects were generally small, three of the pre-treatments had a significant effect on δ 13 C or δ 18 O values. The use of Sudan Black B for vital identification caused a significant enrichment in the 13 C of the samples (0.24‰).In addition, sample oxidation with hydrogen peroxide and ultrasonic cleaning each led to a slight decrease in δ 18 O values (-0.18‰, in both cases). Our results demonstrate that Sudan Black B should be avoided prior to isotopic analysis. Bengal Rose showed no significant effect and should be used instead for staining. Because palaeoclimatic studies are based in small isotopic shifts, we discourage the pre-analysis use of unnecessary harsh cleaning treatments of foraminifera shell samples that may lead to isotopic fractionation and hence confound ecological interpretation.

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Section: Resultssupporting

confidence: 63%

Effects of sample pre-treatment on the δ13C and δ18O values of living benthic foraminifera

Serrano

Mateo

2008

Chemical Geology

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“…Empty and disarticulated valves were then thoroughly rinsed with tap water, distilled water, and ethanol (Merck absolute R.G. for analyses), and permitted to dry at room temperature (for ostracod pretreatment methods, see Danielopol et al, 2002;Keatings et al, 2006;Mischke et al, 2008). All valves were then separated according to species, gender, and instars following Danielopol (1969) and Meisch (2000) and weighed separately (in general adults and A-1 instars) or by batches (small valves and A-2 instars).…”

Section: Living Ostracodsmentioning

confidence: 99%

Controls on ostracod valve geochemistry: Part 2. Carbon and oxygen isotope compositions

Decrouy

Vennemann

Ariztegui

2011

Geochimica et Cosmochimica Acta

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The stable carbon and oxygen isotope compositions of fossil ostracods are powerful tools to estimate past environmental and climatic conditions. The basis for such interpretations is that the calcite of the valves reflects the isotopic composition of water and its temperature of formation. However, calcite of ostracods is known not to form in isotopic equilibrium with water and different species may have different offsets from inorganic precipitates of calcite formed under the same conditions. To estimate the fractionation during ostracod valve calcification, the oxygen and carbon isotope compositions of 15 species living in Lake Geneva were related to their autoecology and the environmental parameters measured during their growth. The results indicate that: (1) Oxygen isotope fractionation is similar for all species of Candoninae with an enrichment in 18 O of more than 3& relative to equilibrium values for inorganic calcite. Oxygen isotope fractionation for Cytheroidea is less discriminative relative to the heavy oxygen, with enrichments in 18 O for these species of 1.7 to 2.3&. Oxygen isotope fractionations for Cyprididae are in-between those of Candoninae and Cytheroidea. The difference in oxygen isotope fractionation between ostracods and inorganic calcite has been interpreted as resulting from a vital effect. (2) Comparison with previous work suggests that oxygen isotope fractionation may depend on the total and relative ion content of water. (3) Carbon isotope compositions of ostracod valves are generally in equilibrium with DIC. The specimens' d 13 C values are mainly controlled by seasonal variations in d 13 C DIC of bottom water or variation thereof in sediment pore water. (4) Incomplete valve calcification has an effect on carbon and oxygen isotope compositions of ostracod valves. Preferential incorporation of CO 3 2À at the beginning of valve calcification may explain this effect. (5) Results presented here as well as results from synthetic carbonate growth indicate that different growth rates or low pH within the calcification site cannot be the cause of oxygen isotope 'vital effects' in ostracods. Two mechanisms that might enrich the 18 O of ostracod valves are deprotonation of HCO 3 À that may also contribute to valve calcification, and effects comparable to salt effects with high concentrations of Ca and/or Mg within the calcification site that may also cause a higher temperature dependency of oxygen isotope fractionation.

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“…H 2 O 2 has been shown to dissolve abiogenic and biogenic calcium carbonates, even when buffered with NaOH [Boiseau and Juillet-Leclerc, 1997;Gaffey and Bronnimann, 1993;Mitsuguchi et al, 2001;Pingitore et al, 1993;Keatings et al, 2006], because H 2 O 2 is a strong enough acid (pK a 11.6) [CRC Press, 2010-2011] to corrode CaCO 3 (equations (2) and (3)):…”

Section: H 2 O 2 Treatmentmentioning

confidence: 99%

“…Thus, the latter authors strongly recommended to either remove of the organic matrix prior to LA-ICP-MS analyses or to mathematically correct for the Me content of the insoluble organic matrix. [5] Previous studies question the effectiveness of different treatment agents and point out that pretreatment itself may alter the trace element composition of the calcium carbonate sample [Keatings et al, 2006;Love and Woronow, 1991;Watanabe et al, 2001]. For example, Gaffey and Bronnimann [1993] studied the effectiveness of sample treatment to remove organic matter from green algae and echinoid skeletons.…”

Section: Introductionmentioning

confidence: 99%

“…Since then Me/Ca (Me stands for divalent metal ions like Mg, Mn, Sr, and Ba which can be substituted for Ca in the calcium carbonate) ratios of biogenic calcium carbonates (e.g., bivalves [Schöne et al, 2011;Vander Putten et al, 2000], corals [Mitsuguchi et al, 1996;Watanabe et al, 2001], ostracods [Holmes, 1996;Keatings et al, 2006], and foraminifera [Barker et al, 2003;Bryan and Marchitto, 2010]) are widely used to reconstruct past environmental conditions [Foster et al, 2008a]. Sample preparation for Me/Ca analysis often includes chemical treatment to remove organic matter from the biogenic calcium carbonate [Gaffey and Bronnimann, 1993].…”

Section: Introductionmentioning

confidence: 99%

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Impact of sample pretreatment on the measured element concentrations in the bivalveArctica islandica

Krause-Nehring

Klügel

Nehrke

et al. 2011

Geochem. Geophys. Geosyst.

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[1] Correlating metal to calcium (Me/Ca) ratios of marine biogenic carbonates, such as bivalve shells, to environmental parameters has led to contradictory results. Biogenic carbonates represent complex composites of organic and inorganic phases. Some elements are incorporated preferentially into organic phases, and others are incorporated into inorganic phases. Chemical sample pretreatment to remove the organic matrix prior to trace element analysis may increase the applicability of the investigated proxy relationship, though its efficiency and side effects remain questionable. We treated inorganic calcium carbonate and bivalve shell powder (Arctica islandica) with eight different chemical treatments including H 2 O 2 , NaOH, NaOCl, and acetone and analyzed the effects on (1) Me/Ca ratios (Sr/Ca, Mg/Ca, Ba/Ca, and Mn/Ca), (2) organic matter (≈N) content, and (3) mineralogical composition of the calcium carbonate. The different treatments (1) cause element and treatment specific changes of Me/Ca ratios, (2) vary in their efficiency to remove organic matter, and (3) can even alter the phase composition of the calcium carbonate (e.g., formation of Ca(OH) 2 during NaOH treatment). Among all examined treatments there were none without any side effects. In addition, certain Me/Ca changes we observed upon chemical treatment contradict our expectations that lattice-bound elements (Sr and Ba) should not be affected, whereas non-lattice-bound elements (Mg and Mn) should decrease upon removal of the organic matrix. For instance, we observe that NaOCl treatment did not alter Sr/Ca ratios but caused unexpected changes of the Mg/Ca ratios. The latter demonstrates that the buildup of complex biogenic composites like the shell of Arctica islandica are still poorly understood.

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Effects of pre-treatment on ostracod valve chemistry

Cited by 40 publications

References 25 publications

Effects of sample pre-treatment on the δ13C and δ18O values of living benthic foraminifera

Effects of sample pre-treatment on the δ13C and δ18O values of living benthic foraminifera

Controls on ostracod valve geochemistry: Part 2. Carbon and oxygen isotope compositions

Impact of sample pretreatment on the measured element concentrations in the bivalveArctica islandica

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