A comparison of the Si/Al and Si/time wet-alkaline digestion methods for measurement of biogenic silica in lake sediments

Abstract

A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk compare a conventional Si-only method to a Si/Al wet-alkaline digestion method, which in theory provides a more robust correction for concentrations of non-BSi. Late glacial/Holocene-aged sediment from Lake Baikal, Russia was used for the comparison. Results showed no significant difference between the two techniques, indicating that existing Si-only BSi methods are suitable for reconstructing environmental changes when levels of digested non-BSi are low to moderate.

A reassessment of late glacial – Holocene diatom oxygen isotope record from Lake Baikal using a geochemical mass‐balance approach

“…A number of studies, however, have shown that fossilized diatoms can contain up to 1 wt% Al (see Koning et al ., 2007, and references within). Recent work on fully purified MIS 5e diatom samples from Lake Baikal shows Al concentrations of 0.08% (1σ = 0.02) (Swann, 2010). Although this level of diatom‐bound Al typically only alters modelled δ 18 O diatom within the limits of analytical reproducibility (0.34‰) it nevertheless remains important to account for this contribution.…”

Palaeo-seasonality of the last two millennia reconstructed from the oxygen isotope composition of carbonates and diatom silica from Nar Gölü, central Turkey

“…Firstly, some minerogenic material will be removed by the first fluorination stage before d 18 O measurements are made (Swann and Leng, 2009). Secondly, diatom frustules can incorporate Al into their skeletons and therefore Al% in the samples will not just reflect minerogenic contamination (Beck et al, 2002;Koning et al, 2007;Swann, 2010). However, because of the difficulties and uncertainties of correcting for these components, these two factors were not accounted for in this study.…”

Pliocene diatom and sponge spicule oxygen isotope ratios from the Bering Sea: isotopic offsets and future directions

“…2) and verified by XRF analyses, with aluminium concentrations in the range of 0.23-0.40 % (typical fossil diatom aluminium concentrations ca. 0.30 wt% (Swann, 2010)). Sponge spicules were predominantly found in samples from the > 38 µm fraction, constituting 0-87 % of the biogenic silica assemblage, the rest made up by diatoms (Table S1).…”

“…The use of oxygen isotopes in palaeoenvironmental research is well documented for both lacustrine and marine environments, predominantly from carbonate fossils, but more recently from siliceous microfossils (Emiliani, 1955;Duplessy et al, 1988;Leng and Marshall, 2004;Lisiecki and Raymo, 2007). Of the latter, diatoms (unicellular algae with a siliceous skeleton; class Bacillariophyceae) are most widely used for oxygen isotope analysis with numerous studies showing how changes in the oxygen isotope ratio of diatom silica (δ 18 O diatom ) reflect changes in temperature and the δ 18 O of ambient water (δ 18 O water ) (Shemesh et al, 1992;Swann and Leng, 2009). The majority of this work has also shown that there are few, or no, intra-or inter-species isotope offsets in diatoms (e.g.…”