【摘要】 采用水动力弥散和吸附理论建立了表流湿地水-土界面磷通量模型,定义了湿地汇-源转换的临界水体磷浓度值．模型揭示,湿地对磷的截留是水动力弥散和吸附共同作用的结果．在湿地建成运行初期,吸附作用明显,临界浓度值较低,湿地较好地发挥截磷功能．随着湿地的运行,土壤吸附趋于饱和,吸附作用减弱,水动力弥散变为主导因素,临界浓度值增大,使湿地除磷功能减弱,在一定条件下,反而可能释放磷．本文建立的磷通量模型具有明确的物理基础,能解释湿地对磷去除功能退化的机理和汇-源转换条件．应用模型对抚仙湖马料河湿地的观测数据作了初步解释,该湿地运行两年后,临界磷浓度值为0．58 mg/L,湿地除磷功能明显衰退．更多还原

【Abstract】 A mathematical model was presented to calculate phosphorus flux across water-soil interface of construc- ted wetlands by employing hydrodynamic dispersion and sorption theory.A critical value of inflow phosphorus con- centration(C_R)was derived from the model.The critical value can be used to indicate the shift condition as nutri- ents sink or source of wetlands.According to the model,removal of phosphorus is a joint effect of hydrodynamic dispersion and sorption.During the first few years after construction of wetlands,the sorption process is dominant resulting in a low value of C_R.During that period,the condition of the wetland as a nutrient sink can be easily sat- isfied,which make the wetland effectively remove phosphorus.After several years’ running,the wetland soil may become sorption-saturated,which make the hydrodynamic dispersion process dominant.This further results in an increased value of C_R.At that stage,the condition of the wetland as a nutrient sink may be hardly met,and the wetland may function as a nutrient source rather than a sink.The model presented in this paper is physically based and can explain the decline of phosphorus removal efficiency of a wetland with time and the shift condition as a sink or a source.The model was used to interpret the observation data of a constructed wetland right upstream of Fuxian- hu Lake,Yunnan Province.It was concluded that the wetland did not have apparent phosphorus removal effects af- ter two years’ operating with a value of 0.58 mg/L for C_R.更多还原