Bicarbonate is a chemical compound with the formula HCO3. It is commonly found in nature as rock deposits, such as limestone and marble, or dissolved in water as sodium bicarbonate (NaHCO3) or potassium bicarbonate (K2CO3). In biological systems, it plays an important role in maintaining the acid-base balance. For example, carbon dioxide is transported through the bloodstream bound to bicarbonate ions, which can neutralize excess acids and help regulate pH levels. Bicarbonate also has various other uses such as a leavening agent in cooking or as an antacid for heartburn relief.