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| Titel |
Soil weathering rates in 21 catchments of the Canadian Shield |
| VerfasserIn |
D. Houle, P. Lamoureux, N. Bélanger, M. Bouchard, C. Gagnon, S. Couture, A. Bouffard |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 16, no. 3 ; Nr. 16, no. 3 (2012-03-06), S.685-697 |
| Datensatznummer |
250013204
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| Publikation (Nr.) |
 copernicus.org/hess-16-685-2012.pdf |
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| Zusammenfassung |
| Soil mineral weathering represents an essential source of nutrient base
cation (Ca, Mg and K) for forest growth in addition to provide a buffering
power against precipitation acidity for soils and surface waters. Weathering
rates of base cations were obtained for 21 catchments located within the
temperate and the boreal forest of the Canadian Shield with the geochemical
model PROFILE. Weathering rates ranged from 0.58 to 4.46 kmolc ha−1 yr−1
and their spatial variation within the studied area was
mostly in agreement with spatial variations in soil mineralogy. Weathering
rates of Ca and Mg were significantly correlated (r = 0.80 and 0.64) with
their respective lake concentrations. Weathering rates of K and Na did not
correlate with lake concentrations of K and Na. The modeled weathering rates
for each catchment were also compared with estimations of net catchment
exportations. The result show that modeled weathering rates of Ca were not
significantly different than the net catchment exportations while modeled
weathering rates of Mg were higher by 51%. Larger differences were
observed for K and Na weathering rates that were significantly different
than net catchment exportations being 6.9 and 2.2 times higher than net
exportations, respectively. The results for K were expected given its high
reactivity with biotic compartments and suggest that most of the K produced
by weathering reactions was retained within soil catchments and/or above
ground biomass. This explanation does not apply to Na, however, which is a
conservative element in forest ecosystems because of the insignificant needs
of Na for soil microorganisms and above ground vegetations. It raises
concern about the liability of the PROFILE model to provide reliable values
of Na weathering rates. Overall, we concluded that the PROFILE model is
powerful enough to reproduce spatial geographical gradients in weathering
rates for relatively large areas as well as adequately predict absolute
weathering rates values for the sum of base cations, Ca and Mg. |
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