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| Titel |
Variations of soil profile characteristics due to varying time spans since ice retreat in the inner Nordfjord, western Norway |
| VerfasserIn |
Ana Navas, Katja Laute, Achim A. Beylich, Leticia Gaspar |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074152
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| Zusammenfassung |
| In the Erdalen and Bødalen drainage basins located in the inner Nordfjord in western Norway
the soils have been formed after deglaciation. The climate in the upper valley part is
sub-arctic oceanic with an annual areal precipitation of ca 1500 mm. The lithology in Erdalen
and Bødalen consists of Precambrian granitic orthogneisses on which Leptosols
and Regosols are the most common soils. Parts of the valleys were affected by
the Little Ice Age glacier advance with the maximum glacier extent around 1750
BP.
In this study five sites on moraine and colluvium materials were selected to examine the
main soil properties of the most representative soils found in the region. The objective was to
assess if soil profile characteristics and pattern of fallout radionuclides (FRN’s) and
environmental radionuclides (ERN’s) are affected by different stages of ice retreat. Soil
profiles were sampled at 5 cm depth interval increments until 20 cm depth. The
Leptosols on the moraines are shallow, poorly developed and vegetated with moss
and small birches. The two selected profiles show different radionuclide activities
and grain size distribution. At P2 profile where ice retreated earlier (ca., 1767)
depth profile activities of FRN´s are more homogenous than in P1 that became
ice-free since ca. 1930. The sampled soils on the colluviums outside the LIA glacier
limit became ice free during the Preboral. The Regosols present better developed
profiles, thicker organic horizons and are fully covered by grasses. Activity of 137Cs
and 210Pbex concentrate at the topsoil and decrease sharply with depth. The grain
size distribution of these soils also reflects the difference in geomorphic processes
that have affected the colluvium sites. Lower activities of FRN´s in soils on the
moraines are related to the predominant sand material that has less capacity to fix the
radionuclides. Lower 40K activities in Erdalen as compared to Bødalen are likely related to
soil mineralogical composition. All profiles show disequilibrium in the uranium
and thorium series. These results indicate differences in soil development that are
consistent with the age of ice retreat. In addition, the pattern distribution of 137Cs and
210Pbexactivities differs in the soils related to the LIA glacier limits in the drainage basins. |
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