Sulfuric Acid: Its Potential for Improving Irrigation Water Quality

Abstract

The 2 major environmental problems of Arizona and the southwest are the alkalinization of soil and water by irrigation and air pollution from copper smelting. It is proposed that the amelioration of both problems may be solved through a common process. This is the production of sulfuric acid from sulfur dioxide, which is the main pollutant of smelter effluent gases. The conversion process is cheap and easy, and the sulfuric acid could then be added to irrigation waters to increase the solubility of CA carbonate in the soil, thereby decreasing alkalinity. Lower alkalinity results in increased soil permeability and increased water use efficiency by plants. The potential market for sulfuric acid in irrigation was calculated, on the basis of neutralizing 90% of the bicarbonate ion concentration in Colorado River water and Arizona well water, to be about 1.6 million tons annually, representing about 1/3 of the sulfur now dissipated by smelters as air pollution. This market includes both the Imperial Valley of California and the Mexicali Valley of Mexico, both of which are currently experiencing mounting salinity problems. Salinity itself is not amenable to this treatment, but the cumulative increase in NA and bicarbonate may be slowed and reversed, leading to gradual soil stabilization.