白洋淀总氮的时空分布及污染特征分析

Spatial and temporal distribution features and pollution sources of the total nitrogen in Lake Baiyangdian

于2009—2010年春、夏、秋、冬季分别对白洋淀典型点位上覆水、间隙水及底泥中的总氮（TN）进行了监测,对总氮质量浓度间的相关关系进行了分析。结果表明：秋季上覆水总氮质量浓度为1.08-1.54mg/L,与其他季节相比质量浓度最低,即秋季各采样点总氮污染程度最轻;各采样点间隙水中的总氮质量浓度均高于上覆水,表明底泥中的氮有向水体中扩散的趋势,内源污染不容忽视;上覆水、间隙水、底泥中总氮质量浓度线性相关系数均小于0.2,不存在相关性。采用地理信息系统（GIS）为数据处理平台,生成各采样点的总氮质量浓度专题图。根据各采样点总氮在间隙水和底泥中的分配系数,结合专题图,将污染源分为3类———鱼鸭养殖区、生活污染源和水生植物生长区,对3类污染源的污染特征进行了分析。

This article intends to present the investigation results of the spatial and temporal distribution features and pollution sources of the total nitrogen in Lake Baiyangdian. To accomplish our investigation, we had been keeping our monitoring activities for over three months, that is, May, August and October in 2009, and one month, that is, March, in 2010.In our monitoring practice, we kept mon-i toring the total nitrogen changing situation in the overlying water, the interstitial water and sediment in the lakewhile choosing five monitoring sites in the fish-farming zone, duck-raising zone, living-garbage dumping site, the sewage outlet and the aquatic plants-farming area, respectively. In proceeding with our monitoring and investigation activities, we have carried out analysis of the changing situations, aiming to find the significant variations of the total nitrogen content in the overlying water, the interstitial water and the sediment by using SPSS software. The results indicate that the total nitrogen concentrations of overlying water in autumn stand in a range of 1.08-1.54 mg/L, which is the lowest during the four seasons of a year. That is to say, the pollution level of the total nitrogen is the slightest in this season. However, the total nitrogen concentration in the interstitial water proves higherthan the homologous overlyingwater, which reveals that nitrogen tends to diffuse from the sediment to overlying water. In addition, the linear correlation coefficient between the overlying water, the interstitial water and the sediment proves to be less than 0.2, with significant linear correlation of the total nitrogen observed. When using the Geographic Information System （GIS） as a platform of spatial data processing, the spatial distribution of the total nitrogen can be expressed figuratively in a thematic map generated by GIS. Based on the distribution coefficient comparison among the interstitial water, the sediment and the thematic map, we have divided the nitrogen po-l lutant sources into three different types： the nitrogen pollutant sources from the aquiculture zones, the home garbage sources and the aquatic plant area. As a result, we have made clear some characteristic distinctions amongthe three kinds of pollution sources in the spatia-l temporal distribution and pollution degrees. And, in turn, we have further analyzed the pollution features of the three pollutant sourcesmentioned in the paper. Thus, we believe that the conclusion we have made as the result of investigation is of importance and helps to expand the understanding of the eutrophication mechanism of the env-i ronment protection of Lake Baiyangdian.