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In order to provide insight into the characteristics of dissolved gaseous mercury(DGM)transformations and gaseous mercury flux emission from water surface to atmosphere,The one sampling sites was chosen for mercury flux from air/water surface and five sampling sites were chosen for dissolved gaseous mercury(DGM)in artificial eutrophication reservoir(Changshou reservoir).Three measurement campaigns were conducted from June 2013 to Jan 2014.The average concentrations of DGM were measured in warm season(46±17 pg L-1)were three times higher than those in the warm-cold transition season DGM(14±15 pg L-1),cold season(17±8 pg L-1)and during cold season campaign,DGM concentration did not show clear seasonal trend in the depth profiles.Dissolved gaseous mercury was significantly positively correlated with temperatures in warm-cold transitions season with significantly positively linear correlation coefficients of 0.507(p<0.01; ANOVA),and dissolved gaseous mercury correlated with dissolved oxygen with linear correlation coefficients of 0.370(p<0.05; ANOVA)in warm-cold transitions season.Generally DGM concentrations in surface water of Changshou reservoir are oversaturated and it was significantly positive correlated with UVR.Hg0 emission from the high DOC concentration aquatic system is the predominant process of DGM formation.The average TGM concentrations during the sampling campaigns(5.9±7.26 ng m-3)were highly elevated comparing to the results observed in North America lakes and the global background value.The seasonal and diurnal variations of Mercury fluxes from water surface in warm season were observed,and the peak values of mercury flux occurred around the noon,and the lowest values of mercury flux occurred around the midnight.No consistent diurnal patterns in mercury flux from air/water in cold season were observed.solar induced Hg reduction was the predominant process producing DGM in surface water and bacteria reduction processes may be important in the bottom of eutrophic reservoir system.