Effects of Airborne Particulates on Nitrogen Fixation in Legumes and Algae

Abstract

This paper presented some of the effects of anthropogenic sulfur compounds along with the phytotoxic elements in the stack emissions from coal-fired electrical facilities and smelters on diazotrophic processes. S0/sub 2/ damage to conifers is evident for 48.3 km (30 miles) north of the present smelter site. Inhibition of nitrogen fixation by SO/sub 2/ or its oxidation products involves either a direct effect on nitrogenase or on photosynthesis. In either case, the result is an increased dependence on combined soil nitrogen for growth. Data presented in Fig. 3 for anabaena suggest that nitrogenase is more sensitive to acid rain than is the photosynthetic mechanism. Treatment of anabaena with sodium bisulfite solutions at pH 5.3 effected a 30% reduction of N/sub 2/ fixation at 1 ppM HSO/sub 3/ which is equivalent to 9 ppB SO/sub 2/. The loss of any combined nitrogen in the already nitrogen-poor grassland soils would be expected to reduce yields of rangeland grasses. Similarly, the loss of the nitrogen contributions by the soil-binding terricolous lichens would be serious. The utility industries suggest that any loss of combined nitrogen derived from diazotrophs would be supplied via NO/sub 3/ from stack emissions as the oxidation products of NO/sub 3/more » would be available to the plants. Recall that the nitrogenase activity is reduced by the addition of combined nitrogen. However, the scenario, based on ecological principles, would predict that the diazotrophs would lose their physiological advantage and disappear from a system in which combined nitrogen was supplied by industrial emissions resulting in a dependence on anthropogenic nitrogen which is emitted along with other phytotoxicants. Should the anthropogenic source cease, the stage for a biological catastrophe is set with resulting desertification of the fumigated plains ecosystem.« less