Page Banner

United States Department of Agriculture

Agricultural Research Service

Title: Phosphorus Flux from Reservoir Bottom Sediments in Lake Eucha, Oklahoma

Authors
item Haggard, Brian
item Moore, Philip
item Delaune, Paul - UNIV OF ARKANSAS

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 26, 2004
Publication Date: March 1, 2005
Citation: Haggard, B.E., Moore Jr, P.A., Delaune, P.B. 2005. Phosphorus flux from reservoir bottom sediments in Lake Eucha, Oklahoma. Journal of Environmental Quality. 34:724-728.

Interpretive Summary: Phosphorus (P) inputs into reservoirs include external sources from the watershed and internal sources from the reservoir bottom sediments. This study quantified sediment P flux in Lake Eucha, Oklahoma, USA, and evaluated the effectiveness of chemical treatment to reduce sediment P flux. We collected sediment cores from three sites at Lake Eucha and estimated sediment P flux under aerobic conditions (dissolved oxygen present in the overlying water) and under anaerobic conditions (dissolved oxygen was removed from the overlying water). Sediment P flux was approximately four times greater under anaerobic conditions compared to aerobic conditions. Alum treatment of the intact sediment-water columns reduced sediment P flux under anaerobic conditions. Overall, internal sediment P flux was about 20% of the annual phosphorus load from the watershed, i.e. external sources. Thus, P management strategies in the Ozarks should consider both internal sources from reservoir sediments and external catchment sources.

Technical Abstract: Phosphorus (P) inputs into reservoirs include external sources from the watershed and internal sources from the reservoir bottom sediments. This study quantified sediment P flux in Lake Eucha, Oklahoma, USA, and evaluated the effectiveness of chemical treatment to reduce sediment P flux. Six intact sediment-water columns were collected from three sites in Lake Eucha near the reservoir channel at depths of 10-15 m. Three in-tact sediment and water columns from each site were incubated for 21 d at ~22°C under aerobic conditions, and three in-tact cores were incubated for 21 d under anaerobic conditions (N2 with 300 ppm CO2). After 21 d, the overlying water in the cores was purged with air and then treated with aluminum sulfate (alum) and incubated for 14 d again under aerobic or anaerobic conditions. Sediment P flux was approximately four times greater under anaerobic conditions compared to aerobic conditions. Alum treatment of the intact sediment-water columns reduced (8X) sediment P flux under anaerobic conditions. Internal P flux (1.03 and 4.40 mg m-2 d-1 under aerobic and anaerobic conditions) were greater than external P flux (0.13 mg m-2 d-1), and the internal P load (12 Mg yr-1) from reservoir bottom sediments was almost 27% of the external P load (~45 Mg yr-1) estimated using a calibrated watershed model. Thus, P management strategies in the Ozarks should consider both internal sources from reservoir sediments and external catchment sources.

Last Modified: 7/30/2014
Footer Content Back to Top of Page