| 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. |
| 关键词: 人工湿地 汇-源功能 水动力弥散 吸附 磷通量模型 |
| DOI：10.18307/2007.0107 |
| 分类号: |
| 基金项目:国家自然科学基金(40471018);中国科学院南京地理与湖泊研究所所长基金(CXNI-GLAS-2004-1);教育部留学回国人员科研基金联合资助. |
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| Shift of phosphorus sink-source functions of constructed wetlands and a theoretical explanation |
|
ZHANG Qi
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Nanjing Institute of Geography & Limnology, CAS, Nanjing 210008, P.R.China
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| Abstract: |
| A mathematical model was presented to calculate phosphorus flux across water-soil interface of constructed wetlands by employing hydrodynamic dispersion and sorption theory.A critical value of inflow phosphorus concentration ( CR) was derived from the model.The critical value can be used to indicate the shift condition as nutrients 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 CR.During that period, the condition of the wetland as a nutrient sink can be easily satisfied, 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 CR.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 Fuxianhu Lake, Yunnan Province.It was concluded that the wetland did not have apparent phosphorus removal effects after two years'operating with a value of 0.58 mg/L for CR. |
| Key words: Constructed wetland sink-source function hydrodynamic dispersion sorption phosphorus flux model Constructed wetland sink-source function hydrodynamic dispersion sorption phosphorus flux model |
