Arch. Pol. Fish.     Vol. 14     Fasc. 2            2006      p. 271-282

ORGANIC CARBON AS AN INDICATOR OF VARIATIONS IN THE TROPHIC STATE OF TWO LAKES LOCATED IN THE UPPER REACHES OF THE ŁYNA RIVER (MAZURIAN LAKELAND, POLAND)

Julita Dunalska*, Bogusław Zdanowski**, Konrad Stawecki**, Jakub Pyka**

*Chair of Environmental Protection Engineering,
University of Warmia and Mazury in Olsztyn, Poland
**Department of Hydrobiology, The Stanisław Sakowicz Inland
Fisheries Institute in Olsztyn, Poland

ABSTRACT. Seasonal variations in the content of the dissolved (DOC) and particulate (POC) fractions of organic carbon were investigated in the waters of lakes Święte and Łańskie. The SUVA260 parameter, which is the value of absorbance normalized against DOC, was used in the qualitative description of dissolved organic matter. The results of the investigations indicated that the concentration of organic carbon was higher in Lake Święte, which is evidence that this basin is more productive. High concentrations of DOC in summer accompanied by low SUVA260 values indicate that the main source of organic matter in this basin is primary production. This is confirmed by the high chlorophyll content, low visibility, and oxygen over-saturation in the surface water layer. In accordance with the criteria proposed by Thurman (1985), while both of the studied lakes are mesotrophic, the range of DOC concentration in Lake Święte indicates that the eutrophication process there is more advanced.

Key words: TOC, DOC, POC, SUVA260, TROPHY, LAKE

CORESPONDING AUTHOR:

Dr inż. Julita Dunalska, Uniwersytet Warmińsko-Mazurski, Wydział Ochrony Środowiska i Rybactwa, Katedra Inżynierii Ochrony Środowiska, ul. Prawocheńskiego 1, 10-957 Olsztyn; Tel./Fax:+48 89 5234257; e-mail: jultad@uwm.edu.pl