Quantification of the Sediment Phosphorus Available to Aquatic Macrophytes

The specific activity of phosphorus taken up by three species of submergent macrophytes grown in partitioned containers and rooted in 32P-labeled sediments was shown to be identical to the specific activity of the sediment mobile phosphorus as measured by two techniques. Therefore, the mobile phosphorus, as determined by isotopic dilution, represents the total pool of sediment phosphorus available to macrophytes. The ability to measure and to specifically label this pool will allow the testing of hypotheses concerning the role of macrophytes in phosphorus cycling.