Response to Comment on “The Chemical Nature of Phosphorus in Subtropical Lake Sediments”, by Kenney et al

Polyphosphate is a quantitatively important and dynamic component of the sedimentary phosphorus in many lakes. Kenney et al. correctly note that we misrepresented their data on polyphosphate in Lake Apopka in our article on the phosphorus composition of subtropical lake sediments, and we regret this error. However, we reiterate that their operationally defined heat extraction procedure overestimates polyphosphate in lake sediments because it includes phosphorus from a number of non-polyphosphate sources. In contrast, our measurements by solution 31 P NMR spectroscopy provide direct quantification of polyphosphate in Lake Apopka sediments and are therefore closer to the true values. Future studies addressing the origins and dynamics of polyphosphate in the environment should employ analytical procedures that unequivocally identify and quantify polyphosphate.