CALL FOR PROPOSALS:

ORGANIZERS

  • Harvey Thorleifson, Chair
    Minnesota Geological Survey
  • Carrie Jennings, Vice Chair
    Minnesota Geological Survey
  • David Bush, Technical Program Chair
    University of West Georgia
  • Jim Miller, Field Trip Chair
    University of Minnesota Duluth
  • Curtis M. Hudak, Sponsorship Chair
    Foth Infrastructure & Environment, LLC

 

Paper No. 8
Presentation Time: 10:15 AM

CLIMATE CHANGE EFFECTS ON THE MECHANISMS OF INTERNAL PHOSPHORUS LOADING AND ALGAL ECOLOGY IN ALKALINE EUTROPHIC LAKES


BALLARD, Nathaniel C., Earth & Atmospheric Sciences, University of Alberta, Centennial Centre for Interdisciplinary Science 2-223, Edmonton, AB T6G 2E3, Canada, nballard@ualberta.ca

Recent and rapid eutrophication of two alkaline lakes followed the onset of anomalous atmospheric temperatures in central Alberta. Historical changes in sediment C, N, P content from two hypereutrophic lakes correlated with molar S:Fe and Fe:Mn ratios, and a reorganization of algal assemblages. Pore-water samples retrieved from cores collected in seven Central Alberta alkaline lakes suggested that P retention in sediments was regulated by Fe rather than Ca. Simultaneous release of alkalinity generating ions and P occurred in Fe deficient pore-water regardless of saturation with respect to hydroxyapatite. Higher temperatures, lower redox potentials and accelerated internal P-loading established positive feedbacks that lead to diminished sediment P-binding capacity of sediments via sequestration of un-reactive Fe by S and a modification of algal assemblages. As many lakes subject to internal P-loading are becoming more productive in the absence of catchment development, sediment Fe-S-P dynamics may inform efforts towards mitigating climate impacts on the water quality, the aesthetics, and the growth of harmful algal blooms in alkaline eutrophic lakes.
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