Water Quality Modeling in Southeastern Lake Management: A Case Study of Lake Lanier, Georgia
Abstract
A model of lake biogeochemical cycling is presented that challenges the traditional paradigm of phosphorus cycling related to iron release in the hypolimnion. Traditional lake nutrient models posit that anoxic hypolimnetic waters induce iron oxihydroxide dissolution, thus leading to phosphorus release during the fall mixis. A one-dimensional (vertical) lake nutrient model is used to account for observed temperatures, dissolved oxygen, specific conductance, and pH profiles in Lake Lanier, a eutrophic Southeastern impoundment. Our model reproduces observations that show benthic release of soluble iron during anoxic conditions in the fall. This increase in soluble iron concentrations, however, is not accompanied by an increase in phosphorus release, presumably due to large inventories of iron minerals in benthic sediments generated from watershed soil erosion. We hypothesize that undissolved iron minerals effectively sequester benthic phosphorus, thus inhibiting nutrient availability. Instead of fall release, we see algal productivity (via phosphorus release) during the summer in shallow embayments where oxic pelagic conditions predominate.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.H42G..07Z
- Keywords:
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- 1030 Geochemical cycles (0330);
- 1806 Chemistry of fresh water;
- 1845 Limnology;
- 1857 Reservoirs (surface);
- 1871 Surface water quality