Effects of human disturbance on nitrification and denitrification potential in the Min River estuarine wetland

The reed wetland in the Min River estuary was chosen as study object,and the effects of human disturbance(aquaculture pond,pollutant discharge and agricultural activity) on nitrification and denitrification potential in the wetland soil were measured.The nitrification and denitrification potential in the wetland soils were significantly affected by human disturbance,the nitrification potential ranked from highest to lowest as: paddy soilaquaculture pond sedimentsoil near discharge outletreed wetland soil,the maximum nitration ratio was 103.45%,99.38%,12.58% and 4.16%,respectively,while the order of dentrification potential in the four soils were opposite,the maximum denitrification ratio was 21.89%,26.95%,78.15% and 88.28%,respectively.The greater the human disturbance,the stronger the nitrificaiton potential,and the weaker the denitrification potential.The NO3--N contents were important indicator for the difference of nitrification and denitrification potential in soils under different human disturbance.The soil pH were significantly related to the nitrification and denitrification,while the contents of soil organic matter,total nitrogen,total phosphorus and dissolved organic carbon and electric conductivity did not show significant correlation with the nitrification and denitrification.The increase of nitrification potential and decrease of denitrification potential induced by human disturbance can increase the risk of nitrate nitrogen leaching in the Min River estuary.