According to Hanna Instruments , acidity can be caused by mineral or organic acids, or by carbon dioxide as carbonic acid.
Acidity of aqueous solutions contributes to corrosiveness and influences the rates of biological processes. For these reasons acidity is monitored in fish farming, soil testing, environmental testing, treated wastewater discharge, lakes and rivers. The Total Exchangeable Acidity (TEA) measures the total amount of soil acidifiers (hydrogen, aluminum, iron and manganese) in meq/100 g unit, equivalent to 1000 parts per 100 g of soil. A high value of total exchangeable acidity means a low soil pH level. Soil with high acidity can damage some crops.