An evaluation of a newly developed method with required beneficial qualities for measuring pCO2 from fresh water : Test-study performed in a small boreal stream network, south west of Sweden during March – October 2013 and 2014

Abstract: Studies have concluded that streams emit CO2, which indicates that natural sources of Greenhouse Gases can contribute to climate changefeedback. Why this is of interest is to be able to make reliable climate models. These studies are however debated, since there are differentmethods to measure CO2 evasion from streams which conclude that different hydrological and chemical factors are affecting the gas exchange themost. It is based on an upside-down-placed chamber in the streams, containing a sensor which is able to directly measure the partial pressure ofCO2 (pCO2) in streams. An advantage with this method is that it is built on cheap equipment and therefore can be afforded to cover a bigcatchment with differing hydrological factors. The aim for the thesis is to evaluate the usefulness of this new method by running several statisticalanalyses on the collected data and also by comparing the trend from the statistical results to other methods statistical trends of pCO2. What can beconcluded by this study is that discharge affects the pCO2 in streams and it often appears with a negative correlation. Also, diurnal patterns ofpCO2 seem to appear, with a peak before lunch and minimum levels in the afternoon, which could indicate that pCO2 are dependent onphotosynthesis/respiration and/or temperature. These conclusions are of interest to understand how C acts in freshwater and respond to the climatechange. The study has to be extended with investigation of how more factors affect pCO2 and also some improvement for the method, before itcan be fully used.