The role of hydrogen peroxide in natural aquatic media

Chemical and biochemical processes defining the H₂O₂ cycle in natural waters and in biological objects are examined. Assessments are given of the inflow of H₂O₂ into surface waters from the atmosphere; data are collated on the H₂O₂ content of sea and fresh water. Photochemical, catalytic and biochemical processes make the main contribution to H₂O₂ formation. The interaction between intracellular redox processes of aquatic microorganisms and the redox state of aquatic media is discussed. Biotic and abiotic processes for the decomposition of H₂O₂ in natural waters and the role of free radicals connected with the H₂O₂ cycle in the self-purification of natural aquatic media are examined. Data are presented which indicate the important role of H₂O₂ in the formation of the biological wealth of natural waters. The bibliography includes 289 references.