Phosphorus cycling in ionically polluted Onondaga lake, New York

A synthesis of the P cycling in Onondaga Lake, New York, is presented, with particular emphasis on the impact of the attendant chemical pollution. The lake has been the focus of a restoration program aimed at reducing phytoplankton biomass through reduction of external P loads. The chemical pollution has altered the behavior of P in at least four ways: (1) reduced vertical mixing, (2) enhanced chemical reactivity of P, (3) increased rate of deposition of P, and (4) reduced availability of sedimentary P. These features reflect very nonconservative behavior of P in the lake, which should facilitate the positive response of the lake to further restoration efforts. The failure of Onondaga Lake to respond to major reductions in external P loading achieved by 1981 reflects the degree to which the system was originally overloaded. Internal P cycling, and P concentrations, in the lake would increase if the loading of ionic material from the major source was discontinued, due to the reversal of existing pollution-based alterations to the P cycle.