A modified method for biogenic silica determination |
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| Authors: | Christian Ohlendorf Michael Sturm |
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| Institution: | (1) Geomorphology and Polar Research (GEOPOLAR), Institute of Geography, University of Bremen, Celsiusstr. FVG-M, Bremen, 28359, Germany;(2) Sedimentology Section/SURF, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Dübendorf, 8600, Switzerland |
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| Abstract: | We describe a modified method for the determination of biogenic silica (BSi) in lacustrine sediment samples with BSi concentrations
>0.5% SiO2 (detection limit). To speed up the leaching procedure (48 samples per day), we suggest the use of Teflon autoclaves that
can be left unattended (no stirring of the solution) for 3 h at 100°C in an oven. We suggest a volume correction by Na measurement
to account for volume errors during pipetting off a hot solution. We also propose to carry out a correction for minerogenic
silica by the simultaneous determination of Al in the leachate. Analytical precision and accuracy of the proposed method are
2.4% (relative standard deviation) and 70–110% recovery (relative to the mean of four international reference sediment samples),
respectively. Additionally, we demonstrate that pre-treatment of the samples with H2O2 and/or HCl prior to alkaline leaching is not necessary for all samples. Due to the great diversity of lacustrine and marine
sediments, however, the pre-treatment procedure should be tailored for samples from different sites. |
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| Keywords: | Biogenic silica NaOH-extraction ICP-OES Teflon autoclaves |
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