This project is funded by the State of Vermont's Department of Environmental Conservation.

The project is 2-fold:

First we are working on defining the total phosphorus load contained within the sediments in St. Albans Bay and the adjoining wetlands of Stevens Brook near the St. Albans Bay town park. We will compare this with similar studies completed in 1982 (Ackerley) and 1994 (Martin et. al.) to ascertain how much that P load has changed in the past 22 years.

Second, we are tring to understand the process by which sediment-bound P may be released from the sediment, into the water column. This process may be critical in the formation of algal blooms in the area and an important piece of information regarding the best

A general picture of the process which we are attempting to evaluate may be found below.

Ferric oxyhydroxide (FeOOH) minerals are very good at taking up phosphorus . When the phosphate (PO₄^3-) is sorbed (essentially stuck on the mineral surface), P is generally not available to algae and stays out of the water column. When the sediment is more oxidized (i.e. the top of the sediment has some oxygen in it), then these FeOOH minerals will keep the P in the sediment. If the sediment becomes more reduced on a seasonal basis through the increased activity of microorganisms which breathe in oxygen and consume it, then other organisms which can breathe in iron or sulfate, the FeOOH minerals will dissolve or turn into iron sulfide minerals, which would release the P into the water column.

We are attempting to evaluate this process in sediments of St. Albans Bay by defining the amount of oxygen, iron, sulfur, and manganese occuring in the sediments. If the sediment chemistry changes markedly thorugh the summer and this compares to the movement of P in the sediments, we know more about the process driving P release and entrappment in the sediments. We collect sediment cores and use voltammetric microelectrodes in those cores to do this: