Sulfuric Acid: Its Potential for Improving Irrigation Water Quality
Affiliation
Department of Agricultural Chemistry and Soils, University of Arizona, TucsonIssue Date
1971-04-23Keywords
Water resources development -- Arizona.Hydrology -- Arizona.
Hydrology -- Southwestern states.
Water resources development -- Southwestern states.
Alkaline soils
Air pollution
Sulfur compounds
Irrigation water
Arid lands
Southwest U.S.Colorado RiverGroundwaterEconomic feasibilityArizonaSodiumBicarbonatesCarbonatesSulfurCalciumSoil chemical propertiesWater qualityIon exchangeSulfuric acidSulfur dioxide
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Copyright ©, where appropriate, is held by the author.Collection Information
This article is part of the Hydrology and Water Resources in Arizona and the Southwest collections. Digital access to this material is made possible by the Arizona-Nevada Academy of Science and the University of Arizona Libraries. For more information about items in this collection, contact anashydrology@gmail.com.Publisher
Arizona-Nevada Academy of ScienceAbstract
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.ISSN
0272-6106Related items
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Effect of irrigation water quality, sulfuric acid and gypsum on plant growth and on some physical and chemical properties of Pima soilField and laboratory experiments to determine the effect of the quality of irrigation water and the combination effects of the quality of water and chemical amendments (Gypsum and H ₂SO₄) on growth and yields of sudangrass, total soluble salt and ionic distribution and the infiltration rates of a Pima soil were conducted. Pima soil was classified as calcareous saline-sodic soil. A field experiment was conducted on the University of Arizona Experimental Farm at Safford, Arizona, for a period of five years. During the first three years, three qualities of water as supplied by well, river and city were used. During the last two years, these waters were coupled with two chemical amendments, gypsum and sulfuric acid. The experiment was a randomized split plot design with nine main plots and 27 subplots and three replications. The rates of the amendments were arbitrarily chosen 1 and 1.72 ton/acre of H ₂SO₄ and gypsum respectively. Four harvests were made over the two-year period and city water treatment gave the best growth and yield of sudangrass as compared to well and river water treatments. H ₂SO₄ and gypsum increased the yield significantly in comparison to the control in 1975. No significant effects of the chemical amendments on the growth and yield of sudangrass were obtained in 1976. Significant negative correlations between the EC and ESP of the first two feet of soil and yield of sudangrass were obtained. Soil analysis indicated that significant decrease in the pH and ESP of the soil resulted from H ₂SO₄ application with the three water treatments. Gypsum reduced pH and ESP significantly just with well water treatment. Due to the stratified texture of soil profile, ions and salts accumulated in the center of the sampled profile. Infiltration rates were higher for well water treatments than for city water treatments. H ₂SO₄ increased the infiltration rates significantly with all water treatments; gypsum increased infiltration only with well water treatment. Infiltration was further studied in the laboratory using soil columns. Two rates of acid and two rates of gypsum were used (1 or 5 and 1.72 or 8.6 ton/acre H ₂SO₄ and gypsum respectively). The higher rate of H ₂SO₄ gave the highest infiltration rate and the lowest infiltration rates were obtained with control with all water treatments. The low rate of H ₂SO₄ and the high rate of gypsum gave similar infiltration rates with the three water treatments. Gypsum treated soil columns required more water to be leached to a specific EC than H ₂SO₄ treated and control columns. More salt can be removed from the soil per unit volume of water with H ₂SO₄ treatment than gypsum or untreated soil. The poorest quality of irrigation water required the least time and amount of water needed to reach equilibrium between the solid and solution phases of soil. The EC of effluent was found to be an index to predict the presence of gypsum and lime in the soil under very low water penetration. Regression equations were developed to predict the time and depth of water required to leach one foot of Pima soil column to a specific EC with a given quality of water and a given type and rate of chemical amendments (H ₂SO₄ and gypsum). A regression equation was developed to estimate the EC of the saturation extract from that of 1:1 soil :water ratio for Pima soil.
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The role of a saline water supply and sulfuric acid in increasing irrigated land at Gila Bend, ArizonaIn this study, well and drainage water were mixed at different rates, and treated with varying amounts of H₂SO₄ to determine if drainage water could supplement ground water supplies and if H₂SO₄ would improve the irrigation water quality of the water mixtures. This study showed that adding amounts of H₂SO₄ equivalent to 15 percent of CO₃ + HCO₃ in irrigation water reduced the detrimental effect of salinity on soil properties and plant growth. In such cases H₂SO₄, which is becoming abundant as an industrial by-product, could be an economic aid in reducing adverse effects of excessive levels of exchangeable sodium in irrigated soils.
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The effects of selected nitrogen and sulfur applications on soil pH, water soluble sulfate, DTPA extractable iron, manganese, copper and zinc on selected Arizona soilsThis study consisted of two experiments to determine the effects of selected N and S application on soil pH, water soluble sulfate and DTPA extractable Fe, Mn, Cu and Zn on selected Arizona soils. The soils in the second experiment were incubated at or beyond saturation. Iron and Mn showed significant reduction; Cu and Zn were generaly unaffected. The soil pH remained fairly near neutral and S was not readily converted to SO₄⁻². The soils in the second experiment were drier and in addition were subjected to repeated N and S applications. Soils with low buffering capacities tended to become acidic and have significant amounts of Fe and Mn. Sulfur was more readily converted to SO₄⁻² under drier conditions. Copper and Zn were generally unaffected. Lime (CaCO₃) as a correction measure for soil acidity and excessive Mn was also studied. Additions of lime kept or raised the soil pH to near neutral and significantly lowered extractable Mn.
