Phosphorus adsorption-desorption from soils and sediments with a photosynthetically elevated PH
Flaishans, Jonathan Mark
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Eutrophication alters the quality of surface water, limiting its use for drinking water and recreation. A notable chemical alteration to surface waters is a photosynthetically elevated pH, where phytoplankton production raises the pH due to the depletion of aqueous carbonate species. Elevated pH limits phosphorus (P) adsorption to iron oxides, releasing P into solution through alkaline desorption. This study characterizes suspended sediments (SS) in Georgia Piedmont streams in an effort to better understand P desorption mechanisms in terms of a photosynthetically elevated pH. SS behave like topsoils at low solution P concentrations but are able to sorb high P concentrations like subsoils. Alkaline P desorption from SS and cultivated topsoils is substantial at high sediment loading. Cultivated topsoils pose the greatest risk to causing eutrophic waters through alkaline P desorption. Subsoils act as P sinks in the aquatic environment and pose little risk when exposed to a photosynthetically elevated pH.