SEDIMENTARY PHOSPHORUS IN THE BAY OF QUINTE, LAKE-ONTARIO

Phosphorus distributions in sediments of the Bay of Quinte were measured. Principal fractions in most samples were (in order of decreasing concentration) P associated with CaCO3, residual organic P, associated with Fe and Al hydrous oxides, and P in the fulvic acid fraction. Concentrations of P in each fraction were followed at 3-wk intervals from May to October and on some additional dates at two or more sites. There were only two systematic changes in concentration over this time. The amount of P incorporated in the sedimentary biomass increased during the summer, probably at a time of high microbiological activity; this was followed by a sharp decrease and another slower increase in late summer. Available P steadily increased during the growing season, but returned to near the previous year's value 12 mo later. Dissolved P in water adjacent to the sediments showed a peak in concentration corresponding to the decrease in biomass P in midsummer. The results are consistent with a picture of P cycling in which forms of the element are first incorporated in the biomass, but are later released to the water column or to available sites on the sediment upon decomposition of the biomass.