Influence of Thiol Compounds on Redox State of Natural Waters in the Republic of Moldova

Background

Monitoring the ecological status of natural waters provides the necessary information about their well-being. In addition, due to the complexity and even more diversity of the sources of pollution, it is essential to evaluate water quality in a complex manner using a wide range of physical, chemical, and biological parameters. Natural waters have the capacity for self-purification (Gladchi, 2018), which represents a complex series of biological, chemical, and physical processes that partially or entirely restore their initial chemical composition (Figure 1). However, the ecological state of water bodies on the country's territory suggests that the intensity of these processes is low.

Figure 1.

General scheme of self-purification of water basins

The biological self-purification processes are the most active and effective at reestablishing the aquatic object's natural composition among all other self-purification processes, including chemical and physical ones. However, research in the field of ecological chemistry show that the valuable biological state of natural waters as a habitat for hydrobionts is actually formed by the chemical processes of self-purification (Blonschi, 2022b). All self-purification chemical processes come down to a dynamic balance between reducing and oxidative equivalents. This balance cannot be estimated using traditional hydrochemical parameters, so there are specific parameters required, such as the redox state of the waters.