Cleaning and pre-treatment procedures for biogenic and synthetic calcium carbonate powders for determination of elemental and boron isotopic compositions
DeCarlo, Thomas M.
MetadataShow full item record
In preparing calcium carbonate samples for the measurement of various geochemical proxies, it is often necessary to remove contaminating phases while leaving the phase of interest altered as little as possible. Here we evaluate the effects of some common cleaning protocols (rinsing (H2O), bleach (~3% NaOCl), hydrogen peroxide (30%), sodium hydroxide (0.006 – 0.1 M NaOH), and acid leaching (0.05 N HNO3)) on the elemental (Li, B, Na, Mg, Sr, Ba, Pb, and U) and boron isotope composition of both biogenic and synthetic calcium carbonates formed in marine environments. In untreated samples, the presence of elevated concentrations of Na and Mg, the most abundant cations in seawater, can be reduced with minimal cleaning (e.g. rinsing). Cleaning protocols that cause partial dissolution are problematic, especially for samples that are compositionally heterogeneous because the remaining sample may be biased towards particular phases with distinctive elemental or isotopic compositions. We show that the use of either acid or unbuffered hydrogen peroxide can lead to partial dissolution which was associated with an increase in the U/Ca ratio of the remaining sample. Bleaching or rinsing with water did not result in significant sample dissolution, suggesting these cleaning techniques may be safely used on heterogeneous samples. Cleaning treatments, other than those resulting in significant dissolution of heterogeneous samples, had no significant effect on δ11B, suggesting that boron isotopes are generally robust to the effects of sample pre-treatment.
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Chemical Geology 398 (2015): 11-21, doi:10.1016/j.chemgeo.2015.01.019.
Showing items related by title, author, creator and subject.
Wang, Jinbo; Flierl, Glenn R.; LaCasce, Joseph H.; McClean, Julie L.; Mahadevan, Amala (American Meteorological Society, 2013-08)A new method is proposed for extrapolating subsurface velocity and density fields from sea surface density and sea surface height (SSH). In this, the surface density is linked to the subsurface fields via the surface ...
Formation of Subtropical Mode Water in a high-resolution ocean simulation of the Kuroshio Extension region Rainville, Luc; Jayne, Steven R.; McClean, Julie L.; Maltrud, Mathew E. (2007-03-09)A high-resolution numerical model is used to examine the formation and variability of the North Pacific Subtropical ModeWater (STMW) over a 3-year period. The STMW distribution is found to be highly variable in both space ...
Delman, Andrew S.; McClean, Julie L.; Sprintall, Janet; Talley, Lynne D.; Yulaeva, Elena; Jayne, Steven R. (American Meteorological Society, 2015-05)Eddy–mean flow interactions along the Kuroshio Extension (KE) jet are investigated using a vorticity budget of a high-resolution ocean model simulation, averaged over a 13-yr period. The simulation explicitly resolves ...