Assessment of the buffer capacity of waters in small lakes in Purovsky region

About the authors:

Tatyana A. Kremleva, Dr. Sci. (Chem.), Professor, Department of Organic and Ecological Chemistry, University of Tyumen; t.a.kremleva@utmn.ru

Alexandra S. Kononova, Student, Institute of Chemistry, Tyumen State University

Abstract:

The aim of this work is to determine the stability of small lakes concerning the processes of acidification by calculating the buffering capacity of natural water. The decrease of pH in natural waters is caused by the arrival of acidifying sulfur and nitrogen oxides in the atmosphere and in water. Acidification of reservoirs has extremely negative consequences, promotes admission of heavy metals, changes the ionic composition of water, and reduces the ability of natural waters to self-regeneration. The low-mineralized water of small lakes of the northern regions is particularly vulnerable to acidification processes. The criteria for stability of natural waters are the indicator of acid-neutralizing capacity, the level of hydrocarbons, and the value of the buffer capacity of natural waters. To calculate the buffer capacity in this paper we use the following indicators of the chemical composition of water: the pH value (pH), organic content (TOC) and inorganic (TIC) forms of carbon. Concentrations of conjugated forms of natural components of acid-base systems are calculated on the basis of representations of the acid-base equilibria in solutions of carbonic acid and humic acids. The total buffer capacity of natural waters is calculated as the sum of humic and hydrocarbonate buffer capacity. The paper shows that the critical value is the value of the buffer capacity of 15-20 μeq/dm3. For 9 lakes of Purovsky region (Yamalo- Nenets Autonomous Okrug) buffer capacity is calculated. On the basis of these data we determine which reservoirs are the most stable and vulnerable to acidification.

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