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Updated: May 12, 2026

Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading
Published on: March 6, 2014
Glacial rock flour enhances phytoplankton growth in phosphorous- and trace metal-depleted environments
Jørgen Bendtsen1,2, Kristina Vallentin Larsen1, Niels Daugbjerg3
1Centre for Glacial Rock Flour Research, Globe Institute, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark.
Abstract:
Glacial rock flour (GRF) is a fine-grained clay to silt-sized material formed beneath glaciers where bedrock is abraded to fine powder. GRF in meltwater rivers constitutes a major source of continental material to the ocean. Here, we investigate the bioavailability of minerals in GRF and show that GRF increases the biological productivity in incubation experiments with an Arctic green alga, Pyramimonas diskoicola. Essential trace metals such as iron and manganese and the macronutrient phosphorus were biologically available from GRF within 3-6 days. In particular, mobilization of iron supplied the exponential growth of microalgal cells as efficiently as from an iron-replete growth medium, whereas growth rates in iron-depleted treatments without GRF were reduced by more than 60%. Hence, GRF stimulates phytoplankton growth and, therefore, constitutes an important nutrient and trace metal source in polar and subpolar coastal areas.
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