Effects of acid precipitation on soil leachate quality: computer calculations

• Main Authors: Sposito, G., Page, A.L., Frink, M.E.
• Language: unknown
• Published: 2022
• Subjects: 54 ENVIRONMENTAL SCIENCES; 60 APPLIED LIFE SCIENCES; ACID RAIN; ENVIRONMENTAL EFFECTS; SOIL CHEMISTRY; RESPONSE MODIFYING FACTORS; AGRICULTURE; COMPUTER CALCULATIONS; FERTILITY; G CODES; LEACHING; MINERALS; PH VALUE; ATMOSPHERIC PRECIPITATIONS; CHEMISTRY; COMPUTER CODES; DISSOLUTION; INDUSTRY; RAIN; SEPARATION PROCESSES; Carbonic acid
• Online Access: http://www.osti.gov/servlets/purl/6458528; https://www.osti.gov/biblio/6458528; https://doi.org/10.2172/6458528

The multipurpose computer program GEOCHEM was employed to calculate the equilibrium speciation in 23 examples of acid precipitation from New Hampshire, New York, and Maine, and in the same number of mixtures of acid precipitation with minerals characteristic of soils in the three states mentioned. Between 100 and 200 soluble inorganic and organic complexes were taken into account in each speciation calculation. The calculations performed on the acid-precipitation samples showed that the metals (including heavy metals) and the sulfate, chloride, and nitrate ligands would be almost entirely in their free-ionic forms, while the phosphate, carbonate, ammonia, and organic ligands would be in their protonated forms. This result was independent of the geographic location of the acid precipitation and the month of the year in which the sample was collected. The speciation calculations on the precipitation-soil mineral mixtures showed that aluminum and iron levels in a soil solution affected by acid precipitation would be significantly higher than in one whose chemistry is dominated by carbonic acid. The higher levels found were caused by the lower pH value of acid precipitation as well as by complexes formed with inorganic and organic ligands. It was also shown that soil cation exchangers would adsorb preferentially heavy metals, such as Cd and Pb, which are found in acid precipitation.