Amount concentrations in aquatic chemistry

Usually, two main terms for concentration are used: amount concentration and mass concentration. Mass concentrations can significantly distort the actual presentation of inorganic and organic compounds in the mixture. They cannot be used when comparing quantity and properties of different compounds, when explaining reaction kinetics, reaction mechanisms and when investigating relationships between concentration and chemical or biological activity. In these cases it is necessary to prefer amount concentrations. "Equivalent concentration" is based on the charge balance of ions in the solution and not on their actual number. The dimension of the equivalent concentration is the same as that of amount concentration (e.g., mmol l-1) which concerns also ANC or BNC (alkalinity or acidity).