Nitric acid: Environmental effects
Description
Nitric acid is a very corrosive compound when in concentrated form such as that commonly used in industrial and chemical processes. It is present in nature in very minute amounts. Severe thunderstorms can produce temperatures high enough to generate nitrogen dioxide which combines with water to form nitric acid. This is either rained or washed out of the atmosphere in very low concentrations. Nitric acid from this source readily reacts with ammonia in the atmosphere to form ammonium nitrate.
Entering the environment
Nitric acid exists in the atmosphere in the gas phase. The atmospheric removal processes for gaseous nitric acid are by wet and dry deposition. The estimated half-life and lifetime for dry deposition of nitric acid is 1.5 to 2 days and 2 to 3 days, respectively, and efficient rain out during episodic precipitation events. Nitric acid reacts with gaseous ammonia to form particulate or aerosol nitrate, which in turn is removed by wet and dry deposition of the particles. The average half-life and lifetime for particles in the atmosphere is about 3.5 to 10 days and 5 to 15 days, respectively.
Where it ends up
In the atmosphere, nitric acid is present in very minute quantities as a gas or vapour. It reacts with ammonia in the atmosphere to form a nitrate compound that is unlikely to persist for more than 10 to 15 days. Nitric acid does not build up in plant or animal tissues largely because of its highly reactive properties. In a concentrated form, nitric acid reacts very quickly with many other commonly occurring natural or manufactured substances and compounds. In some cases this can produce a vigorous reaction in the form of a chemical fire or explosion.
Environmental guidelines
No national guideline for nitric acid.
Key
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