Estimation of buffer capacity of model systems and natural waters by experimental and calculation methods

The aim of this work is to teach students to determine the stability of small lakes in relation to acidification processes by calculating the buffer capacity of water. A decrease in the pH of natural waters is caused by the influx of acid-forming oxides of sulfur and nitrogen into the atmosphere and water bodies. An increase in the acidity of water bodies has extremely negative consequences, contributes to the leaching of heavy metals, changes the ionic composition of water, and reduces the ability of natural water bodies to heal themselves. Low salinity waters of small lakes in the northern regions are especially vulnerable to acidification processes. The indicators of acid-neutralizing ability, the content of hydrocarbons, the value of the buffer capacity of natural waters are used as criteria for the stability of natural waters. To calculate the buffer capacity, the following indicators of the chemical composition of waters were used in this work: hydrogen index (pH), the content of organic (Corg) and mineral (Cmin) forms of carbon. Concentrations of conjugated forms of components of natural acid-base systems are calculated based on the concept of acid-base equilibrium in solutions of carbonic acid and humic acids.