Selenium Dynamics in Boreal Streams: The Role of Wetlands and Changing Groundwater Tables

Abstract

The concentrations of selenium in 10 catchments of a stream network in northern Sweden were monitored over two years, yielding almost 350 observations of selenium concentrations in streamwater. The export of selenium was found to be systematically greater from forests than from mires. Accounting for atmospheric deposition, which was monitored over four years, there was a net accumulation of selenium in mires, while the export from forest soils was approximately equal to the atmospheric deposition. In forest dominated catchments the concentrations of selenium oscillated rapidly back and forth from high to low levels during spring floods. High selenium concentrations coincided with rising groundwater tables in the riparian forest soils, while low selenium concentrations were associated with receding groundwater. Thermodynamic modeling indicated that precipitation of elemental selenium would occur under reducing conditions in the riparian soils. Since changes in the redox conditions are likely to occur near the transition from the unsaturated to the saturated zone, it is hypothesized that the transport of selenium from forest soils to streams is controlled by redox reactions in riparian soils.

Published in

Environmental Science and Technology
2011, volume: 45, number: 7, pages: 2677-2683
Publisher: AMER CHEMICAL SOC

SLU Authors

• Laudon, Hjalmar

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences and Nature Conservation
Other Environmental Engineering

Publication identifier

• DOI: https://doi.org/10.1021/es102885z

Permanent link to this page (URI)

https://res.slu.se/id/publ/57384