 |
| Titel |
Global spatial distribution of natural riverine silica inputs to the coastal zone |
| VerfasserIn |
H. H. Dürr, M. Meybeck, J. Hartmann, G. G. Laruelle, V. Roubeix |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 3 ; Nr. 8, no. 3 (2011-03-07), S.597-620 |
| Datensatznummer |
250005565
|
| Publikation (Nr.) |
 copernicus.org/bg-8-597-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
| Silica, SiO2, in dissolved (DSi) and particulate (PSi) form, is both a
major product of continental weathering as well as an essential nutrient in
terrestrial and aquatic systems. Here we present estimates of the spatial
distribution of riverine silica fluxes under natural conditions, i.e.
without human influence, to ~140 segments of the global coastal zone.
Focussing on the construction of the DSi budget, natural DSi concentration
is multiplied with discharge of rivers for each segment for documented
basins and segments. Segments with no documentation available are estimated
using clustered information based mainly on considerations of local
lithology, climate, and lake retention. We approximate fluxes of particulate
silica in various forms (PSi) from fluxes of suspended matter, calculated
from existing models. Results have been established for silica fluxes,
concentrations and yields for drainage basins of the different continents,
oceans basins as well as coastal segment basins. For the continental
surfaces actually draining into the oceans (exorheic regions, representing
114.7 million (M) km2), 371 M t y−1 of DSi and 8835 M t y−1
of PSi are transported, corresponding to a mean concentration of
9.5 mg l−1 and 226 mg l−1, and to a mean yield of 3.3 t km−2 y−1
and 77 t km−2 y−1, respectively. DSi yields exceeding
6.6 t km−2 y−1, i.e. >2× the global average, represent
17.4% of the global continental ice-free exorheic area but correspond to
56.0% of DSi fluxes. Pacific catchments hold most of the hyper-active
areas (>5× global average), suggesting a close connection between
tectonic activity and DSi fluxes resulting from silicate weathering. The
macro-filters of regional and marginal seas intercept 33% and 46% of
the total dissolved and particulate silica fluxes. The mass of DSi received
from rivers per unit square area of various oceans ranges over more than one
order of magnitude. When expressed per unit volume and when individual
regional seas are considered this figure ranges over two to three orders of
magnitude, an illustration of the heterogeneity of the land to sea
connection. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|