International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Chromium in an aqueous environment can exist in various redox states, the most common being Cr(III), which is mainly in the form of an aquacomplex, and Cr(VI), which is mainly in the form of chromate ions. The distribution of compounds containing the respective forms of chromium depends on the redox potential, pH, the presence of an oxidizing or reducing agent, the kinetics of oxidation-reduction reactions, the formation of Cr(III) complexes or insoluble salts, and the total concentration of Cr.

Iron in surface waters occurs in a variety of physical and chemical forms, each exhibiting distinct reactivity and environmental behaviour. To advance the understanding of how individual biogeochemical processes interact and how aquatic ecosystems respond to shifts in iron speciation, it is essential to establish reliable analytical approaches. In this context, the development of a procedure capable of determining the most reactive and kinetically labile fractions of Fe(II) and Fe(III) represents a timely and significant challenge in contemporary environmental analytical chemistry.

This article presents a summary of data derived from studies conducted on the seasonal dynamics of microcystins and nutrients in the water of Kokalyane bent in 2023 and 2024. The chromatographic analytical method (HPLC) was employed for the determination of microcystins in water samples from Kokalyane bent. Ten water samples were examined, and traces of microcystins were identified in two samples from 2023 (equivalent concentration of MYC-LR approximately 0,2 μg L^-1). The measured concentrations of total nitrogen ranged from 0,58 to 1,75 mg L^-1, while those of total phosphorus ranged from 0,02 to 0,04 mg L^-1.