Experimental Simulation of the Influence of Temperature on the Migration of Substances from Bottom Sediments

Abstract

The results of experimental investigations of the influence of water temperature on the migration of nutrients, organic matter, and metals from bottom sediments into the aquatic environment are discussed in the paper. It has been found that the increase in water temperature from 5°C to 15&degC resulted in the increase in the concentration of inorganic nitrogen, inorganic and total phosphorus, and dissolved silicon respectively by a factor of 1.6, 1.1, 1.2, and 1.4. The increase in water temperature from 5&degC to 25&degC resulted in the increase in the content of these nutrients by a factor of 1.8, 5.8, 1.9, and 2.5. Water temperature increase influenced the contribution of nitrogen compounds to the total balance of inorganic nitrogen. A relative content of ammonium decreased, whereas the contribution of nitrite- and nitrate ions increased as a result of the process of nitrification. The concentration of readily oxidized organic matter and the total content of organic matter also increased almost by a factor of 1.6 with increasing water temperature from 5&degC to 25&degC. Under such conditions, the concentration of aluminum, manganese, and chromium increased by a factor of 1.9, 3.2, and 2.0. In this case, the content of iron and copper remained almost unchanged due to their occurrence in inaccessible fractions of bottom sediments. Artificial aeration at 25&degC was responsible for an insignificant decrease in the concentration of inorganic nitrogen, inorganic and total phosphorus, dissolved organic matter, and also of dissolved aluminum, manganese, and chromium. It has been found that water temperature increase results in the migration of the studied chemical compounds from bottom sediments. However, this process is not as intensive as, for example, with a deficiency of dissolved oxygen and a decrease in pH and redox potential in the near-bottom layer of water.