Zykubek A: Stoichiometry of carbon forms in a small humic lake, Polish Journal of Environmental Studies. Stoichiometry of carbon forms in a small humic lake

The medium concentration of total organic carbon (TOC) in a small (A=24 ha), shallow (zmax=7 m) and midforest lake Pereszpa in the east of Poland was 15 mgC·dm-3, whereas the concentration of DOC constitutes 90 % TOC. Organic forms of carbon are in balance with inorganic forms, although a wild range of quotient TOC to DIC informs about periodic variability catchment's lake feed with organic compounds or about internal carbon changes. These changes are connected with periodically decreasing POC:chla ratio or increasing quotient DIC:DOC:chla (respectively 240-3155:269-2062:1) in presence of intensive microbiological respiration. In this lake it lead to alternating domination of the plankton organisms characteristic for hetero-, mixo- and autotrophic lakes. Key words: humic lake, dissolved organic carbon, particulate organic carbon, total organic carbon, dissolved inorganic carbon, mixotrophic lake, biogeochemistry