In the Erdalen and Bodalen drainage basins located in the inner Nordfjord in western Norway the soils have been formed after deglaciation. The climate in the uppermost valley areas is sub-arctic oceanic and the lithology consists of Precambrian granitic orthogneisses on which Leptosois and Regosois are the most common soils. The Little Ice Age glacier advance affected parts of the valleys with the maximum glacier extent around AD 1750. In this study five sites on moraine and colluvium materials were selected to examine the main soil properties to assess it soil profile characteristics and pattern of fallout radionuclides (FRNs) and environmental radionuclides (ERNs) are affected by dit[erent stages of ice retreat. The Leptosols on the moraines are shallow, poorly developed and vegetated with moss and small birches. The two selected profiles show dit[erent radionuclide activities and grain size distribution. 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 tully ccv- ered by grasses. Activity of 137Cs and 210Pbex concentrate at the topsoil and decrease sharply with depth. The grain size distribution ot these soils also reflects the diflerence in geomorphic processes that have atíected the colluvium sites. Significant lower mass activities of FRNs are found in soils on the moraines than on colluviums. Variations of ERNs activities in the valleys are related to characteristics soil mineralogical compo20 sition. These results indicate differences in soil development that are consistent with the age of ice retreat. In addition, the pattern distribution of 137Cs and 210Pbex activities differs in the soils related to the LIA glacier limits in the drainage basins.

Financial support from CICYT project EROMED (CGL2011-25486/BTE) is gratefully acknowledged.

28 Pags., 4 Tabls., 6 Figs. ©Author(s) 2014 CC Attribution License.

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