Fluxes of CO2, CH4 and N2O and reservoir metabolism of twelve Mediterranean reservoirsin Southern Spain

Simultaneous fluxes of CO2, CH4 and N2O in twelve reservoirs in Southern Spain during the stratification period and the mixing period were measured using a Picarro G2508 gas analyzer connected to a floating chamber. For each reservoir in each sampling period, we took 3-5 measurements for 40 min. We calculated the daily (from 10 am to 4 pm) average (mean) and the standard error (SE) from these measurements. Flux calculations were based on Zhao et al (2015). To obtain the reservoir radiative forcings we summed the corresponding forcing due to CO2 emissions, the warming potential (GWP) of CH4 in terms of CO2 equivalents, and the warming potential of N2O in terms of CO2 equivalents. We used 34 to convert CH4 in CO2 equivalent and 298 to convert N2O in CO2 equivalent in a 100-year time horizon, including the climate-carbon feedbacks (IPCC 2013). We measured ambient temperature, barometric pressure (HANNA HI 9828), and wind speed (MASTECH MS6252A) at the beginning of each flux measurement. We recorded dissolved oxygen concentration and water temperature using a miniDOT (PME) submersible water logger during the stratification period, and calculated the lake metabolism (i.e., gross primary production, net production and respiration rate) according to Staehr et al (2010).