Incubation of dissolved organic matter was performed in June, August and September 2019 and the difference in dissolved organic carbon and nitrogen concentrations and optical properties of dissolved organic matter were measured before and after incubations. In order to test effect of temperature, incubation were performed during 6 days in situ and under controlled conditions of temperature. Samples were incubated under filtered water so total organic carbon and filtered samples so dissolved organic carbon to test the effect of filtration and partial removing of microorganisms. Incubation were also performed under natural sunlight and under dark conditions to test the exfect of light on degradation. Absorbance indices (i.e. SUVA254, E2:E3 ratio and Sr) were measured with a absorbance spectrometry (Biochrom Ultrospec 3100 pro UV/Visible Spectrophotometer) for events from 18B1 to 18B5 and a Horiba Duetta for events from 19B1 to 19B4. Fluorescence indices (i.e. Fluorescence Index and Beta:Alpha index) were measured with spectrofluorimetry using a Horiba Duetta (events from 19B1 to 19B4).