Phosphorus cycling in ionically polluted Onondaga Lake, New York

Previous investigations had indicated that Onondaga lake, was atypical as regards internal phosphorus cycling. This had been attributed to the large inputs of ionic solutes, particularly calcium, from a chlor-alkali plant. After a brief description of the lake, the authors reviewed available information to assess the effect of this industrial wastewater on the phosphorus cycle in the lake, and concluded that chemical pollution had altered the behaviour of phosphorus by reducing vertical mixing, increasing the chemical reactivity of phosphorus, increasing the rate of deposition of phosphorus, and reducing the availability of sediment phosphorus. As a result, phosphorus in the lake behaved in a non-conservative manner, which should facilitate the response of the lake to further restoration methods. The failure of the lake to respond to marked reductions in phosphorus loading in 1981, following a ban on phosphorus detergents and provision of secondary and tertiary sewage treatment facilities, was attributed to the previous severe overloading of the lake. If discharge of the chlor-alkali waste were discontinued, there would be increases in internal phosphorus cycling and in phosphorus concentrations in the lake.