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| Titel |
Silica cycling in the ultra-oligotrophic eastern Mediterranean Sea |
| VerfasserIn |
M. D. Krom, N. Kress, K. Fanning |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 15 ; Nr. 11, no. 15 (2014-08-12), S.4211-4223 |
| Datensatznummer |
250117543
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| Publikation (Nr.) |
 copernicus.org/bg-11-4211-2014.pdf |
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| Zusammenfassung |
| Although silica is a key plant nutrient, there have been few studies aimed at
understanding the Si cycle in the eastern Mediterranean Sea (EMS). Here we
use a combination of new measurements and literature values to explain the
silicic acid distribution across the basin and to calculate a silica budget
to identify the key controlling processes. The surface water concentration of
∼1 μM, which is unchanging seasonally across the basin, was
due to the inflow of western Mediterranean Sea (WMS) water at the Straits of
Sicily. It does not change seasonally because there is only a sparse
population of diatoms due to the low nutrient (N and P) supply to the photic
zone in the EMS. The concentration of silicic acid in the deep water of the
western Ionian Sea (6.3 μM) close to the S Adriatic are an of
formation was due to the preformed silicic acid (3 μM) plus
biogenic silica (BSi) from the dissolution of diatoms from the winter
phytoplankton bloom (3.2 μM). The increase of 4.4 μM
across the deep water of the EMS was due to silicic acid formed from in situ
diagenetic weathering of aluminosilicate minerals fluxing out of the
sediment. The major inputs to the EMS are silicic acid and BSi inflowing from
the western Mediterranean (121 × 109 mol Si yr−1
silicic acid and 16 × 109 mol Si yr−1 BSi), silicic
acid fluxing from the sediment (54 × 109 mol Si yr−1)
and riverine (27 × 109 mol Si yr−1) and subterranean groundwater
(9.7 × 109 mol Si yr−1) inputs, with only a minor
direct input from dissolution of dust in the water column
(1 × 109 mol Si yr−1). This budget shows the importance
of rapidly dissolving BSi and in situ weathering of aluminosilicate minerals
as sources of silica to balance the net export of silicic acid at the Straits
of Sicily. Future measurements to improve the accuracy of this preliminary
budget have been identified. |
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