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Research article2006Peer reviewed

Landscape control of stream water aluminum in a boreal catchment during spring flood

Cory N, Buffam I, Laudon H, Kohler S, Bishop K

Abstract

Inorganic aluminum (Al) concentrations are critical for defining the biological effects of acidification. The landscape's role in controlling the spatial variability of Al and its speciation has received only limited attention. We analyzed the speciation of stream Al at 14 sites within a 68 km(2) boreal catchment during spring snowmelt, a period of episodic acidity. Three factors that influenced Al at these sites were landscape type (specifically the proportion of wetland areas), stream pH, and dissolved organic carbon (DOC). Forested catchment sites underlain by mineral soils had higher total Al concentrations and greater inorganic Al proportions than catchments with larger wetland areas, despite significantly higher pH. We suggest that this difference results from source limitation of Al in the peat wetlands. The control of Al solubility was dominated by organic complexes, with the organic carrying capacity exceeding Al in the majority of samples. When assessing the inorganic phase, only four percent of the samples were oversaturated with regards to commonly forming secondary Al minerals, with no samples showing supersaturation higher than 10 times with respect to any given solid phase. Inorganic Al rarely exceeded biological thresholds, except for short periods during peak flow in forested areas, despite two-thirds of the streams having minimum pH values below 4.9. Streams with a high percentage of wetland area were associated with lower Al: DOC ratios. The Al: DOC ratios were quite stable in each stream before, during, and after snowmelt, with the exception of isolated spikes in the Al: DOC ratio associated with particulate Al at a downstream site during high flow

Published in

Environmental Science and Technology
2006, Volume: 40, number: 11, pages: 3494-3500
Publisher: AMER CHEMICAL SOC

      SLU Authors

    • Buffam, Ishi

      • Department of Forest Ecology, Swedish University of Agricultural Sciences

      • Laudon, Hjalmar

        • Department of Forest Ecology, Swedish University of Agricultural Sciences

        • UKÄ Subject classification

        Environmental Sciences related to Agriculture and Land-use

        Publication identifier

        DOI: https://doi.org/10.1021/es0523183

        Permanent link to this page (URI)

        https://res.slu.se/id/publ/8198