HR: 0800h
AN: B41D-0755    [Abstracts]
TI: Breaking Down the Yukon River: Analysis of Solute Chemistry in Yukon River Tributaries
AU: * Frederick, Z A
EM: zan@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado Campus Box 450, Boulder, CO 80309-0450,
AU: Striegl, R G
EM: rstriegl@usgs.gov
AF: USGS, Box 25046 MS 413, Denver, CO 80225-0046,
AU: Anderson, S P
EM: suzanne.anderson@colorado.edu
AF: Institute of Arctic and Alpine Research, University of Colorado Campus Box 450, Boulder, CO 80309-0450,
AB: The Yukon River (YR), one of the largest unregulated rivers in the northern hemisphere, drains a diverse assemblage of terrain from glacierized mountains to lowland peatlands underlain by permafrost. Tributaries to the YR can be characterized by the nature of the suspended sediment, inorganic solutes, and dissolved organic matter they carry depending on the topography, geology, and ecology of the individual watersheds. In order to understand how these landscape characteristics affect solute flux from the tributaries we examine surface water data from 43 tributaries to the YR in Alaska and Canada. Principle component analysis (PCA) based on 9 dissolved constituents has been applied to the major tributaries of the YR and has successfully reduced the dimensionality of the data set through non-subjective groupings of variables. Five principle components explain approximately 90% of the total variance in dissolved constituents among rivers within the YR basin that represent 85% of the total Yukon River area. The first principle component (PC 1) shows strong negative (<-0.6) correlations with the major dissolved ions (Ca²⁺, Mg²⁺, SO₄^2-, HCO₃^-) and Sr. PC 2 shows strong positive (>0.6) correlations with Na⁺, Cl^- and SiO₂. PC 3 is represented by inverse loadings of SiO2 (-0.6) and Cl^- (0.6). PC 4 is a nearly unique loading for K⁺ (-0.7), with additional weak loadings for SiO₂ (0.3) and Mg²⁺ (0.2). PC 5 shows weak positive loadings for Ca²⁺ (0.2) and HCO₃^- (0.4) and weak negative loadings for Sr (-0.2) and SO₄^2- (-0.3). This study demonstrates the usefulness of PCA for simplifying a set of surface water solute data for a major river system in order to establish the important factors controlling river chemistry. It is expected that further analysis will resolve specific correlations between the five PC's and subbasin characteristics such as percent of land covered by wetlands, glacier extent, permafrost distribution, and type of underlying bedrock in YR tributaries.
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
DE: 0496 Water quality
DE: 0744 Rivers (0483, 1856)
DE: 0790 Weathering (1625, 1886)
DE: 1806 Chemistry of fresh water
SC: Biogeosciences [B]
MN: 2007 Fall Meeting