Denitrification Rate In Soils From Freshwater And Brackish Marshes In The Minjiang Estuary And Their Responses To Salinity And Nitrogen Input

The estuarine wetland,due to the dual influence of rivers and oceans,leads to differences in the sedimentary grain texture,the main factors denitrification is different in different soils under different circumstances.In recent years,the increasing intensity of human activities has resulted in the increase of nitrogen elements exported to the receiving estuaries from the coastal basins and the global warming leading to the salt water-freshwater mixed area of some estuaries.Based on this,the study selected the sandy loam and loamy soil of Longxiang Island and Shanyutan Wetland?respectively freshwater and brackish water wetland?in the Min River Estuary as the research object.Through indoor cultivation experiments,the study revealed that the Minjiang River Estuary Denitrification Rates of Different Textures in Fresh/Brackish Wetlands and Their Responses to Salinity and Nitrogen Input.The results show that:?1?The change range of sandy soil denitrification rate in Longxiang Island and Shanyutan Wetland?respectively freshwater and brackish water wetland?of Minjiang Estuary were 0.06-0.49 ng N·g-1·h-1 and 0.29?0.65 ng N·g₁·h-1),Loamy soil denitrification rate range were 0.09?2.04 ng N-g-1·h-1 and 5.00?18.22 ngN·g-1·h-1.The highest and lowest seasonal variation of sandy soil denitrification rate occurred in summer?spring?and summer?autumn?,and the highest?lowest?values of loamy soil denitrification occurred in summer and autumn.?2?The sediment denitrification rates of Longxiang Island and Shanyutan Wetland were all higher than sandy soil in four seasons.The same is sandy soil,Shanyutan Wetland four seasons in addition to the denitrification rate in spring,the other three seasons are higher than the Longxiang Island,The same loamy soil,Shanyutan Wetland four-season denitrification rate was significantly higher than the Long xiang Island.Among them,the temperature is not an important factor that affects the seasonal change of sediment denitrification rate,The denitrification rate of sandy soil sediments in Longxiang Island and Shanyutan Wetland had no significant correlation with all the physical and chemical indexes,However,the loamy sediments in Longxiang Island and eel Beach are mainly affected by the combined effect of NO3-N content and organic matter.?3?The average annual denitrification rates of different texture of Longxiang Island and Shanyutan Wetland Sediment showed significant differences with increasing of salinity and nitrogen input,showing the trend of nitrogen>control>saline + nitrogen>saline.The main influencing factors of each treatment denitrification rate are different,and the salt water treatment is mainly affected by the content of C1-;Nitrogen input has a positive effect on denitrification rate of different texture of wetland sediments;Effect of salt and nitrogen treatment on pH and conductivity and NH4' concentration promotion.?4?The average denitrification rate of different materials with different morphological nitrogen input-coupled saline intrusion process in Longxiang Island/Shanyutan Wetland in summer has a great difference,Among them,nitrate nitrogen significantly increased denitrification rate of different textures,while other forms of nitrogen did not show significant?except Longxiang Island sandy soil?.However,the rate of denitrification under salt intrusion coupled with input of different forms of nitrogen was inhibited.