Dissolved and colloidal oxyanion trace elements in the Yukon River system
Abstract
Dissolved and colloidal trace elements were determined in rivers and streams within the Yukon River Basin in Alaska and Canada. Among the oxyanions, we have determined As, Cr, Mo, Re, and V in the dissolved (< 0.02 μm) and colloidal (0.02 - 0.45 μm) phases. Among these elements, Re and Mo are found almost entirely in the dissolved phase. For the other three elements, while most of their < 0.45 μm concentration is in the dissolved phase, they nonetheless have significant colloidal suspended fractions. In general, these colloidal oxyanion concentrations follow colloidal Fe, with somewhat higher colloidal oxyanion/Fe ratios for glacial streams. This is likely a result of significant alumino-silicate colloidal Fe in the glacial streams versus dominant colloidal FeOOH in the non-glacial streams. In the dissolved phase, Mo and Re tend to be correlated as do V and As (and to a lesser extent Cr). V, As, and Cr all show positive correlations with DOC for high DOC streams. However, streams with low DOC show no such trend and frequently have higher V, As, and Cr than the high DOC streams. This suggests control by organic complexation (including retention in soils) for the high DOC systems, and by other processes (e.g., redox chemistry and mineral weathering) in low DOC systems.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.B21B0354S
- Keywords:
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- 1065 Major and trace element geochemistry;
- 1615 Biogeochemical cycles;
- processes;
- and modeling (0412;
- 0414;
- 0793;
- 4805;
- 4912);
- 1806 Chemistry of fresh water;
- 1871 Surface water quality