Internal Nutrient Loads from Sediments in a Shallow, Subtropical Lake

Potential Effects of Sediment Dredging on Internal Phosphorus Loading in a Shallow, Subtropical Lake

“…Phosphorus flux with no dredging was 0.4 mg P/m 2 /day. In studies conducted 10 years ago, maximum P flux measured for mud sediments were in the range of 0.14-1.89 mg P/m 2 /day (Moore et al 1998, Fisher et al 2005. These results suggest that during the last 10 years internal P load from sediments has not changed appreciably.…”

“…Internal dissolved P fluxes, measured in 1988 in Lake Okeechobee, were equivalent to external loads (Moore et al 1998, Malecki et al 2004, Fisher et al 2005. Similarly, the significance of the internal P loads in regulating eutrophication has been demonstrated in other shallow lakes (Anderson and Ring 1999, Graneli 1999, Sondergaard et al 1999, Watts 2000, Steinman et al 2004.…”

“…The deep pelagic region has an extensive area of flocculent mud sediments. The top 10 cm of these sediments contain an estimated 28,600 metric tons of phosphorus (P) (Reddy et al 1996, Fisher et al 2005. Because these sediments are a source of DRP to the water column of Lake Okeechobee (Moore et al 1998, Fisher et al 2005, one possible management technique to improve water quality in the lake is dredging these mud sediments from the lake.…”

“…Concentration of total P and fractions of P are generally higher in recent sediments, related to recent P loading. Although accretion of sediment-bound P suggests that P flux is downward (i.e., from the water column to sediments), the DRP flux is upward (i.e., from sediments to the water column) in response to concentration gradients across the sedimentwater interface (Lijklema 1994, Moore et al 1998, Steinman et al 2004, Fisher et al 2005.…”

Development of Methods for Spatial Modeling of Sediments Quality in Lake Okeechobee, Florida

“…Because of this large sediment pool of P, sediment-water interactions, including diffusive flux and sediment re-suspension, can affect phosphorus dynamics within the Lake's water column (Fisher et al, 2005;James et al, 2005;. These sediment-water interactions can delay changes of in-lake phosphorus concentration to reduced external loads (James & Pollman, 2011).…”