Phosphorus Cycling in Southeastern Piedmont Lakes: An Alternative Pathway
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Author(s)
Parker, Amanda K.
Rasmussen, Todd C.
Advisor(s)
Editor(s)
Hatcher, Kathryn J.
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Abstract
The phosphorus cycling paradigm in lakes is
based on data from systems in northern temperate regions.
Anoxic respiration in the hypolimnion of north-temperate
lakes creates strongly reducing conditions that liberate
dissolved inorganic phosphorus (DIP) from settling
particulates. Hypolimnetic DIP steadily increases during
summer stratification as phosphorus is liberated, and is
mixed throughout the water column at fall overturn. This
paradigm fails to explain phosphorus cycling in Southeastern Piedmont lakes. No increase in DIP is found in
the anoxic hypolimnion during summer stratification; nor
is an increase in DIP observed during fall overturn. We
hypothesize that the conventional paradigm is not appropriate in iron-rich Southeastern Piedmont lakes because:
a) iron-oxide sorption reduces the bioavailability of DIP,
and b) the abundance of oxidized iron prevents DIP accumulation in the anoxic hypolimnion. We use iron-oxide
chemistry to develop an alternate phosphorus cycling
pathway: DIP is released from iron-phosphate particulates
when pH increases due to photosynthesis. This mechanism forms a biogeochemical feedback loop that enhances
algal blooms.
Sponsor
Sponsored and Organized by: U.S. Geological Survey, Georgia Department of Natural Resources, Natural Resources Conservation Service, The University of Georgia, Georgia State University, Georgia Institute of Technology
Date
2001-03
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Proceedings