The Effect Of The Simulated Sulfate Deposition On Nitrous Oxide Fluxes From The Estuarine Freshwater Tidal Marsh In The Min River Estuary

As an important greenhouse gas,nitrous oxide had a great contribution to global warming.In the background that sulfuric acid rain is getting more and more serious in the Fujian province,the effect of the simulated sulfate deposition on nitrous oxide fluxes from the estuarine freshwater tidal Sagitaria trifolia marsh of the Taj iaozhou in the Min River estuary was studied.The experiment treatments included CK treatment[Okg SO₄^2--S/（hm²a）],S60 treatment[60kgSO₄^2--S/（hm²a）]and S120 treatment[120kg SO₄^2--S/（hm²a）].Indoor cultivation experiment was carried out using acetylene inhibition method,the aim was to measure the sediment denitrification rate.The results showed that:（1）The average nitrous oxide flux of CK treatment(58.06μg·m^-2·h^-1)is higher than S60(23.50μg·m^-2·h^-1)treatment,and S60 treatment is higher than S120(20.75μg·m^-2·h^-1)treatment in the Tajiaozhou wetland,which shows that the Tajiaozhou wetland is the source of nitrous oxide emission and the sulfate subsidence could inhibit the nitrous oxide emission.The range of nitrous oxide flux under the CK treatment is from（7.63±26.80）to（257.87±29.91）μg·m^-2·h^-1,The range of nitrous oxide flux under the S60 treatment is from（58.92±58.92）to（173.79±24.52）μg·m^-2·h^-1,The range of nitrous oxide flux under the S120 treatment is from（32.64±32.64）to（40.95±19.14）μg·m^-2·h^-1.The highest nitrous oxide of CK treatment came out in winter and the lowest in spring,The highest nitrous oxide of S60 treatment came out in autumn and the lowest in summer,The highest nitrous oxide of S120 treatment came out in winter and the lowest in summer.（2）This study shows that nitrous oxide flux of monthly and seasonal variations hasn’t any close relationship with air temperature.And The average nitrous oxide flux of CK treatment is higher than S60 treatment and the S60 treatment is higher than S120 trratment,which shows that soil sulfate content could inhibit nitrous oxide emission.Moreover the nitrous oxide flux of CK treatment is mainly affected by soil pH value,while the S60 and S120 treatment are mainly affected by the pore water electrical conductivity.The rest of the physical and chemical properties have not any influence.（3）The highest sediment denitrification rate of CK treatment came out in winter and the lowest came out in summer,the average sediment denitrification rate is-2.66mmol·g^-1 ·h^-1,The highest sediment denitrification rate of S60 treatment came out in spring and the lowest came out in winter,the average sediment denitrification rate is 1.57mmo1·g^-1 ·h^-1,The highest sediment denitrification rate of S120 treatment came out in autumn and the lowest came out in winter,the average sediment denitrification rate is-8.18mmol·g^-1 ·h^-1.Among the three treatmen’ sediment denitrification rate,except for that the sediment denitrification rate of CK treatment is significantly higher than S60 treatment（P<0.05）in winter and the sediment denitrification rate of S60 treatment is significantly higher than S120 treatment（P<0.05）in spring,the three treatments’sediments denitrification rate have no any significantly diffrences in the rest seasons.（4）This study showed that the temperature hasn’t any close relationship with the three treatments’ sediment denitrification rate,which shows that temperature is not the key factor that affects the sediment denitrification rate.The average sediment denitrification rate of S60 treatment(1.57mmol·g^-1 ·h^-1)is higher than CK treatment(-2.66mmol·g^-1 ·h^-1),and the average sediment denitrification rate of CK treatment is higher than S120 treatment(-8.18mmol·g^-1 ·h^-1).In general,sulfate could inhihibit sediment denitrification rate.The sediment denitrification rate of S120 treatment has a close relationship with tidal water Chloride ion content（P<0.05）,the sediment denitrification rate of the S60 treatment has a close relationship with sediment NO_x^--N content（P<0.05）.The other physical and chemical factors have no any significant effect.