The ammonium release of core samplers in Lake Taihu were simulated at different temperatures.The results showed that the area-weighed nitrogen exchange rates in the conditions of 5g,15g, and25gare-16.0±17.6mg/(m²·d),12.6±6.9mg/(m²·d),and34.1±20.8mg/(m²·d),respectively.But the ammonium fluxes were quite different among the sediments from different lake aveas.In respect of the waters that were greatly influenced by external pollution source, there was a positive correlation between the ammonium exchange amount and temperature.In the areas where there are more algal gathering and macrophyte growth, the annual release fluxes of nitrogen were usually greater because of being impacted with deposition of biological detritus on the surficial sediment.The ammonium exchange amount, onthewholelake, wasestimatedtobeabout9960.3±4960.0t/a, ofwhichthesinking flux was about-911±637.9t/a.There appeared source-sink transition at least once in most of the sediment areas.