The Significance Of Phosphorus Released From The Sediment Under Anoxic Conditions In Sodus Bay, N.Y.

Abstract

The goal of this study was to evaluate the loss of phosphorus from the sediment to the anoxic hypolimnion of Sodus Bay, New York. Total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations were monitored weekly throughout the water column in Sodus Bay from 16 May 2001 to 22 September 2001. Increased amounts of TP and SRP into the hypolimnion, during periods of hypolimnetic anoxia, indicated that phosphorus was being released from the sediment. On an annual basis, the sediments contributed 600 kg of phosphorus to Sodus Bay (24 kg/d x 25 days, from 8/18 to 9/12) in 2001. This is 7.5% of the annual input of phosphorus to Sodus Bay from the watershed (8,004 kg P, annual average from 1989 to 1994). If the period of anoxia in the hypolimnion is considered (25 days in the late summer), the amount of phosphorus released by the sediments into the hypolimnion is still 600 kg but the amount entering from the watershed is 123 kg of P. That is, phosphorus release into the hypolimnion is 488% greater than the amount entering from the watershed during this period of the year. Since the sediment is releasing phosphorus at a time when inputs from the watershed are minimal, phosphorus inputs from the sediments may prove to be a more important factor in the stimulation of late summer algal blooms than inputs from the watershed.