Contamination of some reservoirs and lakes in Republic of Bulgaria by microcystins

This paper presents the results from analyses of water samples from 15 Bulgarian reservoirs and lakes for detection of microcystins presence by high-performance liquid chromatography (HPLC) coupled to a ultraviolet (UV) and photo diode array (PDA) detector. In 3 of the studied drinking water reservoirs cyanobacterial blooms were not detected. Cyanobacterial blooms were observed in 6 of 12 investigated water bodies used for fishing and water sports. Microcystis was the dominant cyanobacterial genus. The concentration of total microcystins in the biomasses ranged from 8 to 1070 mu g g(-1) (d.w.). Microcystin-LR and microcystin-RR were the predominant microcystins, followed by microcystin-YR. Presence of dissolved microcystins was obtained in one water sample with concentration of total microcystins 1.64 mu g L-1. Presence of microcystin-LF and -LW or unknown peaks possessing characteristic microcystin-like UV-spectra were not detected. Those first results for occurrence of microcystins in some Bulgarian reservoirs and lakes are a contribution to the knowledge on their distribution.