title: Using stable isotopes to resolve transit times and travel routes of river water: a case study from southern Finland.
abstract: The stable isotopic composition of two rivers, the Vantaanjoki River and the Kokemäenjoki River, in southern and southwestern Finland was studied to resolve the transit times and travel routes of the river water in the two different catchments. The Kokemäenjoki River is dominated by great lake basins whereas the Vantaanjoki River has been reported having a significant groundwater component. The mean residence time of the young surface flow component could be resolved by sine function fitting onto the annual fluctuations of the isotopic signal, and the amount of base flow was estimated by using the isotopic composition of the river and groundwater. In this study, we found that the methods work for simple two component catchments. In more complex cases with three different components mixing, the solution becomes increasingly difficult and requires more study.
authors.affiliation: a Department of Geosciences and Geography , University of Helsinki , Helsinki , Finland.
authors.forename: Paula I A
authors.initials: PI
authors.lastname: Niinikoski
authors.affiliation: b Geological Survey of Finland GTK , Espoo , Finland.
authors.forename: Nina M
authors.initials: NM
authors.lastname: Hendriksson
authors.affiliation: a Department of Geosciences and Geography , University of Helsinki , Helsinki , Finland.
authors.forename: Juha A
authors.initials: JA
authors.lastname: Karhu
mesh_terms: D003903:Deuterium / Q000032:analysis*; D004784:Environmental Monitoring; D005387:Finland; D060587:Groundwater / Q000032:analysis*; D060106:Lakes / Q000032:analysis*; D010103:Oxygen Isotopes / Q000032:analysis; D045483:Rivers; D014872:Water Movements
chemical_list: D010103:Oxygen Isotopes; D003903:Deuterium
keywords: Finland; d-Excess; hydrogen-2; isotope hydrology; mean residence time; oxygen-18; river water; seasonal variations; snow