Читать книгу Fundamentals of Aquatic Veterinary Medicine - Группа авторов - Страница 36

Alkalinity is the ability of the water to accept hydrogen ions and neutralize them and offers a buffering system to reduce pH swings. It is measured by the amount of acid (hydrogen ion) that water can absorb (buffer) before achieving a designated pH. Total alkalinity is expressed as milligrams per liter or parts per million calcium carbonate (mg/l or ppm CaCO₃). It consists of negatively charged bases – carbonates, bicarbonates, and hydroxides. Alkalinity is expressed in equivalent concentrations of calcium carbonate.

Carbonates and bicarbonates are sources of carbon for plants, which is used in photosynthesis to make carbohydrates. Carbonates and bicarbonates are the most common and most important components of alkalinity. A desirable range of total alkalinity for fish culture is CaCO₃ 75–200 mg/l. Carbonate–bicarbonate alkalinity (and hardness) in surface and well waters is produced primarily through the interactions of CO₂, water and limestone. Rainwater is acidic because of exposure to atmospheric carbon dioxide and sulfuric acid (H₂SO₄).