In an electrolyzed solution, the negatively charged particle, or ion, which travels to the anode and is therefore discharged, evolved, or deposited. Also, by extension, any negative ion. Anions are opposed to cations, which carry a positive charge. There must be equal amounts of positive and negative charged ions in any water sample. Following are the common anions in their order of decreasing concentration for most lakes: bicarbonate (HCO3-), Sulfate(SO4--), chloride (Cl-), carbonate (CO3--), nitrate (NO3-), Nitrite (NO2-), and phosphates (H2PO4-, HPO4--, and PO4-- ).
A negatively charged ion in an electrolyte solution, attracted to the anode under the influence of a difference in electrical potential. Chloride (CI-) is an anion.