Abstract

Aluminum ( Al) transfer from soils to surface waters is a crucial determinant of aquatic biodiversity in acidified and/or naturally acid surface waters. Defining how landscapes and acid deposition influence Al export depends on our understanding of the mobilization of Al within catchments. This paper documents the evolution of Al chemistry in water during its transport through a hillslope by using soil water chemistry combined with hydrometric data. Al levels moving laterally from upslope mineral soils were low (< 0.1 mg.L-1). This is not consistent with a vertically infiltrating acidification front mobilizing Al from across the catchment. As water moves laterally downslope into the peaty soils of the riparian zone ( RZ), Al increased along with organic acids and iron. The RZ in this study was thus a net source of Al to soil solution on all 9 sampling occasions where Al was measured, as well as a net source of dissolved organic carbon ( DOC) on another dozen measurement occasions. The potential for Al concentrations being modified during transport through the RZ needs to be accounted for in efforts to relate acid deposition to toxic stream Al concentrations. Organic carrying capacity was in excess of Al for all samples. Only samples from the deeper mineral soils showed supersaturation; however, none of the samples showed degrees of supersaturation high enough for spontaneous mineral precipitation. A key area for further research is how the RZ can sustain a larger Al pool than upslope mineral soils when the supply of Al from these upslope soils to lateral flux is currently lower than that from the RZ. Two possibilities are either episodic downslope transport during periods of high lateral flow, or drainage-induced changes in hydrology that transformed the RZ from an accumulator of Al to a source of Al

Keywords

aluminum; soil; stream; transect; transport; acidification

Published in

Journal of Geophysical Research
2007, Volume: 112, number: G3, article number: G03014
Publisher: AMERERICAN GEOPHYSICAL UNION

SLU Authors

• Cory, Neil

  • Department of Forest Resource Management, Swedish University of Agricultural Sciences
    

• Bishop, Kevin

  • Department of Environmental Assessment, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Fish and Aquacultural Science
Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.1029/2006JG000387

Permanent link to this page (URI)

https://res.slu.se/id/publ/16539