Phosphorus deposition from the epilimnion of Onondaga Lake1

Abstract

The downward flux of inorganic and organic fractions of phosphorus from the epilimnion of calcium-rich, hypereutrophic, Onondaga Lake was determined over 7 months in the water and in sediment traps. Material was collected in sediment traps for short and long periods (average of 4 and 14 days) throughout the study. A linear relationship between overlying concentrations of particulate phosphorus and downward flux (mg P m-2 d-l) of phosphorus was only weakly supported (significant at the 99.5% confidence level, r 2 = 0.156). About 30% of the phosphorus deposited was in inorganic form. The time-averaged flux of particulate phosphorus (45.4 mg P m-2 d-l) was greater than any values in the literature for other systems. The substantial contribution of inorganic phosphorus to total phosphorus deposition and the large magnitude of the overall downward flux may' be attributed to oversaturation with respect to the solubility of calcite in the epilimnion of the lake, which facilitates the sedimentation of phosphorus with calcite and may also enhance the settling of phytoplankton cells. A comparison of the sediment trap data with annual mass balance calculations suggests that phosphorus settling across the metalimnion cycles vertically on the average about three times before it is exported from the lake or incorporated into the sediments.

Supply of phosphorus to the water column of a productive hardwater lake: controlling mechanisms and management considerations

“…Comparable water chemistry data are available for earlier years (i.e., 1980, 1981) and were used to interpret changes in lake chemistry. Atomic absorption spectrophotometry (Effler and Driscoll, 1985) 9.9 10-, K + Atomic absorption spectrophotometry 4.4 10-FIon selective electrode (Effler and Driscoll, 1985) 2.4 10-' Temperature 9.1 C * All according to Standard Methods (APHP, 1985), except Fe 2 +.…”

“…The lake is dimictic, has a surface area of 11.7 km 2 , a mean depth of 12 m and a maximum depth of 20 m. The lake has a high flushing rate (4 times y -1), and thus responds rapidly to remedial measures (Devan & Effler, 1984). It is a hardwater system (Effler & Driscoll, 1985), naturally enriched with SO42-(1.6 mmol 1-). Onondaga Lake has received municipal effluent and industrial waste for more than a century.…”

“…Selective extraction (Williams et al, 1976) of sediment trap collections suggests that P co-precipitates with CaCO 3 (s) in the water column. Approximately 30% of the depositing P during May-November 1980 was found to be inorganic; 56% of the P in the surficial sediments of a single deep water location was determined to be inorganic (Wodka et al, 1985).…”

Hydrologic connectivity as a framework for understanding biogeochemical flux through watersheds and along fluvial networks

“…In addition to POM deposition, sediment settling in lakes and reservoirs can deposit C, N, and P that can sorb to charged surfaces (Li et al, 2013;Tanoue and Handa, 1979). This physical retention process is particularly important in relation to P (Wodka et al, 1985) because phosphate (PO 4 ) readily sorbs to sediment particles (Walker and Syers, 1976), but sedimentation processes can also be important in watershed C and N dynamics (Teodoru et al, 2013). Combined physical and biological processes in lakes and reservoirs can decrease annual fluxes of total N, enhance retention of total P (TP) and total suspended sediment (TSS), and decrease annual variability in TSS and TP export in forested and agricultural watersheds (Powers et al, 2014).…”

Biochemogenic Calcite as an Important Component of Matter Turnover in the Eutrophic Mozhaisk Reservoir

“…Trap method (exposition of 4 to 14 days) was used to determine the downward flux of suspended P with a medium rate within seven months (45.4 g P/(m 2 day). More than 30% of this phosphorus was represented by its inorganic form [17], presumably, in the form of phosphate sorbed on particles of biochemogenic calcite.…”