项目名称： 非点源氮迁移路径与源区识别的定量化研究

项目编号： No.40871026

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 无线电电子学、电信技术

项目作者： 张奇

作者单位： 中国科学院南京地理与湖泊研究所

项目金额： 45万元

中文摘要： 非点源氮污染是地表水体的主要污染源之一，精确识别污染源区，量化其贡献是阐明非点源污染机制急需解决的科学问题。本研究以鄱阳湖乐安江流域为研究区，通过高精度分布式地表-地下径流耦合模型与现场水质监测的联合使用，研究非点源氮素的产出与输移机制。基于自主研制的WATLAC模型，建立了乐安江流域分布式地表-地下径流耦合模型。采用73个气象站和6个水文站，对模型进行参数优化，模型模拟精度较高，日纳西效率系数达0.91。基于该水文模型和水质浓度数据，估算得出主要土地利用类型林地和耕地氮素输出系数分别为3.92mg/L和0.71mg/L。全流域总氮、硝氮和氨氮的平均输出率为3.16t/km2/a、0.73t/km2/a和0.20t/km2/a，输出率从上游到下游呈逐渐增大趋势，反映了土地利用类型变化引起的氮输出量的变化。与太湖流域研究结果的对比发现，乐安江流域耕地仍然是氮素产出的主要土地类型，需要引起关注。本研究基于分布式地表-地下径流耦合模拟结果，以新的思路开展非点源氮污染研究，定量界定了氮输出的主要土地利用类型与空间分布，量化了源区的贡献程度,为流域综合管理，有效实施源区控污提供科学依据。

中文关键词： 非点源污染；氮；水文模型WATLAC；源区识别；鄱阳湖

英文摘要： Non-point nitrogen pollution is one of the major pollution sources of surface water bodies. Accurate identification of the source area and quantification of its contribution to the total loads of mass is an important issue that requires to be answered urgently in order to further understand the mechanism of non-point pollution. This project investigated the nitrogen migration mechanism by a joint use of a distributed hydrological model and surface water quality sampling, taking Leanjiang catchment as an example in the Poyang lake watershed. A coupled surface and subsurface water flow model was first constructed for the study area. The model was calibrated against observed daily stream flows measured at 6 points located at different river branches. The calibration was satisfactory with a daily Nash-Sutcliffe efficiency of above 0.90. By employing this hydrological model, the nitrogen export coefficients for the two main land use types of forest and arable lands were estimated, which were 3.92mg/L and 0.71mg/L, respectively. The catchment-averaged nitrogen yield for total nitrogen, nitrate nitrogen and ammonia nitrogen were 3.16t/km2/a, 0.73t/km2/a and 0.20t/km2/a, respectively. The nitrogen yield increases from upstream to downstream area, which is consistent with the change of land use type with more arable land in the downstream area. This work is new in terms of using a fully calibrated high accuracy surface and subsurface water flow model. The results of this research revealed in more detail the non-point pollution mechanism. The outcomes further help to identify the key source areas that have significant impacts on the surface water quality. Scientific evidence is provided from this research to help formulate accurate and rational management strategies to reduce nitrogen pollution.

英文关键词： Non-point pollution; Nitrogen; Hydrological model WATLAC; Source area identification; Poyang lake