The influence of environmental factors on the carbon dioxide flux across the water–air interface of reservoirs in south-eastern Poland

Studies concerning the emission of carbon dioxide(CO_2) were carried out in 2009–2012 for six reservoirs located in four provinces of south-eastern Poland. The CO_2 flux across the water–air interface was measured using the "static chamber" method. The measured fluxes of CO_2(FCO_2) ranged from-30.64 to 183.78 mmol/m~2/day, and the average values varied in the range from-3.52 to 82.11 mmol/m2/day. In most of the cases, emission of CO_2 to the atmosphere was observed. The obtained values of CO_2 fluxes were comparable to values typical for other temperate reservoirs. Analysis of the influence of selected environmental factors on the FCO_2 showed that it depends on parameters characterizing both the sediments and surface water. The CO_2 flux at the water–air interface was positively correlated with parameters of bottom sediments such as porosity, content of organic carbon and total nitrogen; and negatively with p H value and δ~(13)C of organic carbon. In the case of the parameters characterizing surface water, positive dependences on the concentrations of nitrate and total nitrogen, and negative relationships with water temperature and chlorophyll a concentrations, were found.