Redox potential as an important characteristic of the chemical and biological state of surface waters (review)

ABSTRACT

This review summarises literature data on redox potential (Eh) as an essential characteristic of surface waters affecting their ecological and chemical state. We consider the influence of Eh on the migration of nutrients, metals, and metalloids in the ‘bottom sediments – water’ system and its role in the secondary pollution of water bodies. Hypoxia, anaerobic conditions, and reduced Eh leads to an increase in the concentration of nutrients, reduced forms of manganese and iron, due to their migration from bottom sediments to the aquatic environment. This, in turn, contributes to enhanced eutrophication of water bodies. We reviewed the data on the transformation of metal and metalloid compounds depends on the intensity of redox processes resulting their bioavailability, and toxicity to aquatic organisms. Humic substances, as the most common group of dissolved surface water organic substances, exhibit reducing properties and affect the coexisting metals and metalloid species. The intensity of redox processes in surface water will increase under climate change. The issue of redox transformation of elements will need to be considered in the context of developing measures to reduce surface water loading with primarily nutrients and metals, taking into account the possibility of internal pollution of water bodies.

KEYWORDS:

• Redox potential
• surface water bodies
• metals
• metalloids
• nutrients
• ammonium nitrogen
• phosphorus
• iron
• manganese
• chromium
• arsenic
• selenium
• humic substances

Acknowledgements

The authors wish to thank Prof. Jim Smith from University of Portsmouth, UK for his comments on the manuscript and help in improving the English. We also appreciate the anonymous reviewers whose comments enabled us to significantly improve the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Peter Linnik

Prof. Peter Linnik, Doctor of Sciences in Chemistry, 1991; Institute of Hydrobiology of the National Academy of Sciences of Ukraine, 1977; Currently Head of Hydrochemical Department. He is an environmental chemist. Areas of his expertise are (i) Elaboration of methodological approach to investigation of physico-chemical state (Speciation) of metals in natural water; (ii) Investigation of the metal coexisting forms in surface water. Peculiarities of their distribution among water ecosystem components and transformation ways under the influence of intrawater body processes; (iii) Biologically active of different forms of heavy metals; (iiii) Investigation of component composition of dissolved organic matter, including humic substances in surface water bodies. Research on the complexation of metals with various groups of natural organic substances in surface waters.

Volodymyr Osadchyi

Prof. Volodymyr Osadchyi, Doctor of Sciences in Geography, 2008; Ukrainian Hydrometeorological Institute of the State Service of Emergencies of Ukraine and the National Academy of Sciences of Ukraine, 1991. Currently he occupies a position of director. He is an environmental chemist. His scientific interests include a wide range of issues related to the study of processes determining surface waters chemistry under the influence of natural and anthropogenic factors. Interphase distribution of nutrients and pollutants of different nature in the system water-suspended substances-sediments. Study of features of distribution and migration of chemical elements in conditions of increased heat load (water reservoirs - coolers of thermal and nuclear power plants). Chemistry of atmospheric precipitation.

Natalia Osadcha

Prof. Natalia Osadcha, Doctor of Sciences in Geography, 2011; Ukrainian Hydrometeorological Institute of the State Service of Emergencies of Ukraine and the National Academy of Sciences of Ukraine, 1993. Currently Head of the Water Chemistry Department. It deals with the formation of the chemical composition of surface waters under the influence of natural and anthropogenic factors, and investigates their regional manifestations. Methodology of anthropogenic load assessment. A study of humus substances migration regularities in the surface waters of Ukraine is carried out. Thermodynamic calculations of the chemical components' transformation under the action of various factors. Prof. Osadcha teaches a graduate course in processes determining water chemistry.

Rostyslav Linnik

Rostyslav Linnik, PhD, The Taras Shevchenko Kyiv National University, 2004. Currently Associate Professor of the Chemistry Department. He is an analyst chemist. He uses luminescent, spectrophotometric and gel-chromatography technics to enhance the detection of organic substances including humic substances in natural waters. He develops methodological approach to investigate metal speciation in surface water and conducts research of metal binding with organic substances. Dr. Linnik teaches an undergraduate course in analytical chemistry.