Adsorption of Nutrient Elements by the Sediment from Ditch System in a Farmland-Wetland in Guizhou Province,China:Kinetics and Influential Factors

XUE Fei 1,LIU Wen 2,XIA Pin-hua 1,LIN Tao 1,DENG He-xia 1,KONG Xiang-liang 1,3,ZHANG Jun-mei 1(1.Guizhou Key Laboratory for Mountainous Environmental Information and Ecological Protection,Guizhou Normal University,Guiyang 550001,China;2.The Administration Bureau of the Caohai National-Level Natural Reserve in Guizhou,Weining 553100,China;3.Agricultural College,Guizhou University,Guiyang 550001,China)

farmland-wetland;ditch sediment;adsorption;NH 4 +-N;PO 43--P

This research is to investigate the removal effects of ditch system in a farmland-wetland on nitrogen and phosphorus.A simulation experiment was carried out to study the kinetic characteristics of nitrogen and phosphorus adsorptions on the sediment of the agricultural ditch system in Caohai Wetlands.Results showed that the retention rates of the everglade farmland ditch system for TP,TN and NH 4 +-N were 66.7%～79.7%,66.0～76.4% and 82.8～89.3%,respectively.The equilibrium time of adsorption on nitrogen and phosphorus were long,comparing with the sediments from Taihu and Dianchi.With the increasing concentrations of the salinity,SO 42-and NO 3-,the sorption ability of PO 43--P and NH 4 +-N on the sediment declined,respectively.However,the influence of Ca 2+ on PO 43--P sorption might be divided into two patterns:Restraining at low concentration and promoting at high concentration,and Ca 2+ was found to have a significant restraining effect on NH 4 +-N adsorption,with the minimum adsorption value at the Ca 2+ concentration of 5 mg·L-1.