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| Titel |
Predicting riverine dissolved silica fluxes by chemical weathering: results from a hyperactive region and analysis of first-order controls |
| VerfasserIn |
Jens Hartmann, Nils Jansen, Hans H. Dürr, Akira Harashima, Kenji Okubo, Stephan Kempe |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037902
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| Zusammenfassung |
| Silicate weathering and resulting transport of dissolved matter influence the global carbon
cycle in two ways. First, by the uptake of atmospheric/soil CO2, and second, by providing
the oceanic ecosystems via the fluvial systems with the nutrient dissolved silica
(DSi).
Previous work suggests that regions dominated by volcanics are hyperactive or even “hot
spots” concerning DSi-mobilization from the critical zone. Here, we present a new approach
for predicting riverine DSi-fluxes by chemical weathering, emphasizing “first-order”
controlling factors (lithology, runoff, relief, land cover and temperature). This approach is
applied to the Japanese Archipelago, a region characterized by a high percentage of volcanics
(29.1% of surface area).
The presented DSi-flux model is based on data of 516 catchments, covering
approximately 56.7% of the area of the Japanese Archipelago. The spatial distribution of
lithology — one of the most important first order controls — is taken from a new, high
resolution map of Japan. Results show that the Japanese Archipelago is a hyperactive region
with a specific DSi-yield 6.6 times higher than the world average of 3.3 t SiO2 km-2 a-1, but
with large regional variations.
Approximately 10% of its area exceeds 10 times the world average specific DSi-yield.
Slope constitutes another important controlling factor on the mobilization of DSi-fluxes from
the critical zone, besides lithology and runoff, and can exceed the influence of runoff on
specific DSi-yields. Even though the monitored area on the Japanese Archipelago
stretches from about 31Ë to 46Ë N, temperature is not identified as a significant
first-order model variable. This may be due to the fact that slope, runoff and lithology
are correlated with temperature due to regional settings of the Archipelago, and
temperature information is substituted to a certain extent by these factors. Land
cover data also do not improve the prediction model. This may partly be attributed
to misinterpreted land cover information from satellite images. Implications of
results for chemical weathering rates based on lithological information applied are
discussed.
Reference:
Hartmann, J., Jansen, N., Dürr, H.H., Harashima, A., Okubo, K., Kempe S. (2010)
Predicting riverine dissolved silica fluxes into coastal zones from a hyperactive region and
analysis of their first order controls. International Journal of Earth Sciences, 99(1), 207-230.
doi:10.1007/s00531-008-0381-5. |
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