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Soil acidification is the buildup of hydrogen cations, which reduces the soil pH. Chemically, this happens when a proton donor gets added to the soil. The donor can be an acid, such as nitric acid, sulfuric acid, or carbonic acid. It can also be a compound such as aluminium sulfate, which reacts in the soil to release protons.
At low pH, the oxidative stress induced by aluminium (Al 3+) affects soil animals the body of which is not protected by a thick chitinous exoskeleton like in arthropods, and thus are in more direct contact with the soil solution, e.g. protists, nematodes, rotifers , enchytraeids and earthworms .
The term ‘acid sulfate soils’ (ASS) was coined by the Working Party on Nomenclature and Methods for the first International Symposium on Acid Sulfate Soils (1972, Wageningen) to mean soils that contain, or have the potential to produce, sulfuric acid in quantities that cause significant and long-lasting changes in key soil properties. [22]
Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH).Most water, including drinking water, has a neutral pH that exists between 6.5 and 8.5, but acid rain has a pH level lower than this and ranges from 4–5 on average.
A mixture of ammonia gas and water vapor is introduced into a reactor that contains a saturated solution of ammonium sulfate and about 2% to 4% of free sulfuric acid at 60 °C. Concentrated sulfuric acid is added to keep the solution acidic, and to retain its level of free acid. The heat of reaction keeps reactor temperature at 60 °C.
Effect of soil pH on cation-exchange capacity. The amount of negative charge from deprotonation of clay hydroxy groups or organic matter depends on the pH of the surrounding solution. Increasing the pH (i.e. decreasing the concentration of H + cations) increases this variable charge, and therefore also increases the cation-exchange capacity.
Molecular models of the different molecules active in Piranha solution: peroxysulfuric acid (H 2 SO 5) and hydrogen peroxide (H 2 O 2). Piranha solution, also known as piranha etch, is a mixture of sulfuric acid (H 2 SO 4) and hydrogen peroxide (H 2 O 2).
The degree to which a given amount of lime per unit of soil volume will increase soil pH depends on the buffer capacity of the soil (this is generally related to soil cation exchange capacity or CEC). Most acid soils are saturated with aluminum rather than hydrogen ions. Soil acidity generally results from hydrolysis of aluminum. [4]