Phosphorus Flux for Florida Lake Sediments under Different Water Column Spike Concentrations.
(S10-martin949208-oral)
Authors:
C.S. Martin* - Univ. of Florida J.R. White - Univ. of Florida K.R. Reddy - Univ. of Florida
Abstract:
Sediments play a significant role in phosphorus (P) cycling dynamics in lakes. The capacity of bottom sediments to retain or release P to the overlying water column can control the trophic status of a lake, even after the external P load has been curtailed. This study examined the response of lake sediments to changes in P concentrations in the water column in 5 contributory lakes of Lake Okeechobee in Florida.
Intact cores were collected from two stations per lake (total of 150 cores). Five spiked water column concentrations (0, 15, 30, 60, 120 ug L-1) were evaluated in triplicate for P flux under aerobic and anaerobic conditions. The equilibrium P concentration (EPC) was calculated for each station. Initial sediment characterization found predominately mud sediments containing total P concentrations ranging from 118 to 1811.8 mg kg-1 and sand sediments from 40 to 422 mg kg-1. In general, extractable SRP was well correlated with Total P (TP) of the sediments. All five lakes followed the general trend of greater P release from the sediment under anaerobic versus aerobic conditions. Under aerobic
conditions, sediments in 2 of the 5 lakes retained P under all water column SRP concentrations while 3 lakes had an EPC averaging 30 ug L-1. This research will assist water managers in determining the internal load of P during efforts to reduce P export to downstream Lake Okeechobee.
Speaker Information: Chakesha Martin, Univ. of Florida, 106 Newell Hall PO Box 110510, Gainesville, FL 32608; Phone: (352)392-1804 ext 336; E-mail: [email protected]
Session Information: Monday, November 3, 2003, 8:55 AM-11:15 AM Presentation Start: 9:15 AM
Keywords: phosphorus flux; water quality; lake sediments; environment
