Acidifikation

Acidifikation is the process of increasing the acidity of a substance or environment, characterized by a higher concentration of hydrogen ions and a lower pH. It can occur by adding acids, by chemical or biological production of acidic species, or by atmospheric deposition of acid-forming compounds. In environmental science, acidification commonly describes the long-term lowering of pH in soils and aquatic systems, often driven by human activities.

In water and soil, several mechanisms drive acidification. Dissolution of carbon dioxide in water forms carbonic acid, which dissociates to H+ and bicarbonate. Emissions of sulfur dioxide and nitrogen oxides convert to sulfuric and nitric acids, contributing to acid rain and soil/water acidification. In soils, nitrification and the input of ammonium release protons, decreasing pH and leaching base cations such as calcium and magnesium. The result is reduced buffering capacity and altered nutrient availability. In biological contexts, many microorganisms produce organic acids during fermentation, lowering pH at sites of activity, and food industry uses intentional acidification to preserve products.

Impacts depend on ecosystem and buffering capacity. In soils and freshwater, lower pH can increase metal solubility (for example aluminum), harm aquatic organisms, reduce nutrient uptake by plants, and shift species composition. In oceans, progressive acidification affects carbonate chemistry, reducing availability of carbonate ions critical for calcifying organisms such as corals and some plankton.

Measurement and mitigation include monitoring pH and alkalinity, titrimetric determination, and modeling of buffering capacity. Mitigation strategies cover emission reductions of sulfur and nitrogen compounds, liming of acidic soils and waters to restore neutralization capacity, and land and water management to maintain buffering. Acidifikation also has industrial and culinary applications through controlled acidification of foods and beverages for preservation and flavor development.