Biogenic Si analysis in volcanically imprinted lacustrine systems: the case of Lake Rutundu (Mt. Kenya)

Verfasser / Beitragende:
[Lúcia Barão, Gijs De Cort, Patrick Meire, Dirk Verschuren, Eric Struyf]
Ort, Verlag, Jahr:
2015
Enthalten in:
Biogeochemistry, 125/2(2015-09-01), 243-259
Format:
Artikel (online)
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024 7 0 |a 10.1007/s10533-015-0125-0  |2 doi 
035 |a (NATIONALLICENCE)springer-10.1007/s10533-015-0125-0 
245 0 0 |a Biogenic Si analysis in volcanically imprinted lacustrine systems: the case of Lake Rutundu (Mt. Kenya)  |h [Elektronische Daten]  |c [Lúcia Barão, Gijs De Cort, Patrick Meire, Dirk Verschuren, Eric Struyf] 
520 3 |a Diatoms are important primary producers in lake ecosystems and, as a sink for dissolved (DSi) and biogenic silica (BSi) originating from land, can significantly impact the global Si cycle. After burial in lake sediments, resistant diatom frustules can also be used for reconstructions of past ecosystem change. The BSi content of lake sediments is thus often used as a proxy for past diatom productivity, and measured using a time-step analysis of Si extracted in 0.1M Na2CO3. However, studies in soils and ocean sediments have shown that also certain non-biogenic Si fractions are prone to dissolve in alkaline solutions, contributing to a potential overestimate of sedimentary BSi concentration. In lakes, volcanic and terrestrial Si compounds reactive at high pH are likely to interfere with the analysis. In this study we used a continuous analysis of Si and Al extracted in 0.5M NaOH and a new mathematical model improved from Koning et al. (Aquat Geochem 8:37-67, 2002) to distinguish between biogenic and non-biogenic Si fractions in lake-sediment extracts. We tested this approach in 43 samples of a 19,000-year sediment sequence recovered from Lake Rutundu, a volcanic crater lake on Mt. Kenya. Our results show that a significant fraction of the extractable Si is of non-biogenic origin, especially in the part of the sequence deposited during the glacial period. We conclude that this technique is essential for the characterization of different Si phases, and in particular the diatom-derived BSi, in the sediment of lakes situated in volcanic catchments. It allows calculating a correction, based on the distinct Si:Al ratio of each of those Si phases, that eliminates the contribution from non-BSi fractions. 
540 |a Springer International Publishing Switzerland, 2015 
690 7 |a Lakes  |2 nationallicence 
690 7 |a Diatoms  |2 nationallicence 
690 7 |a Volcanic interference  |2 nationallicence 
690 7 |a Alkaline extractions  |2 nationallicence 
690 7 |a Continuous analysis  |2 nationallicence 
700 1 |a Barão  |D Lúcia  |u Ecosystem Management Research Group, Department of Biology, University of Antwerp, Universiteitsplein 1C, 2610, Wilrijk, Belgium  |4 aut 
700 1 |a De Cort  |D Gijs  |u Limnology Unit, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium  |4 aut 
700 1 |a Meire  |D Patrick  |u Ecosystem Management Research Group, Department of Biology, University of Antwerp, Universiteitsplein 1C, 2610, Wilrijk, Belgium  |4 aut 
700 1 |a Verschuren  |D Dirk  |u Limnology Unit, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium  |4 aut 
700 1 |a Struyf  |D Eric  |u Ecosystem Management Research Group, Department of Biology, University of Antwerp, Universiteitsplein 1C, 2610, Wilrijk, Belgium  |4 aut 
773 0 |t Biogeochemistry  |d Springer International Publishing  |g 125/2(2015-09-01), 243-259  |x 0168-2563  |q 125:2<243  |1 2015  |2 125  |o 10533 
856 4 0 |u https://doi.org/10.1007/s10533-015-0125-0  |q text/html  |z Onlinezugriff via DOI 
898 |a BK010053  |b XK010053  |c XK010000 
900 7 |a Metadata rights reserved  |b Springer special CC-BY-NC licence  |2 nationallicence 
908 |D 1  |a research-article  |2 jats 
949 |B NATIONALLICENCE  |F NATIONALLICENCE  |b NL-springer 
950 |B NATIONALLICENCE  |P 856  |E 40  |u https://doi.org/10.1007/s10533-015-0125-0  |q text/html  |z Onlinezugriff via DOI 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Barão  |D Lúcia  |u Ecosystem Management Research Group, Department of Biology, University of Antwerp, Universiteitsplein 1C, 2610, Wilrijk, Belgium  |4 aut 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a De Cort  |D Gijs  |u Limnology Unit, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium  |4 aut 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Meire  |D Patrick  |u Ecosystem Management Research Group, Department of Biology, University of Antwerp, Universiteitsplein 1C, 2610, Wilrijk, Belgium  |4 aut 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Verschuren  |D Dirk  |u Limnology Unit, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium  |4 aut 
950 |B NATIONALLICENCE  |P 700  |E 1-  |a Struyf  |D Eric  |u Ecosystem Management Research Group, Department of Biology, University of Antwerp, Universiteitsplein 1C, 2610, Wilrijk, Belgium  |4 aut 
950 |B NATIONALLICENCE  |P 773  |E 0-  |t Biogeochemistry  |d Springer International Publishing  |g 125/2(2015-09-01), 243-259  |x 0168-2563  |q 125:2<243  |1 2015  |2 125  |o 10533