Carbon and Nitrogen Stable Isotope Fractionation in the Sediment of Lake Bled (Slovenia)

Stable isotope composition of carbon and nitrogen in the sediment and pore water of a eutrophic freshwater lake was studied. Based on changes in the δ¹¹C and δ¹⁵N values of dissolved components and sediment fraction. possible processes involved in the decomposition of sedimentary organic matter are outlined. The relative importance of acetate fermentation and CO₂ reduction was estimated using known mathematical models, and ammonia assimilation by methanogenic bacteria is hypothesised to be the main process governing the isotope fractionation of dissolved nitrogen in pore water.