白洋淀芦苇型水陆交错带水化学动态及其净化功能研究

于2007年3月-11月对富营养化湖泊一白洋淀进行了现场调查，分析了温度、溶解氧（DO）、叶绿素、总磷（TP）及其他水化学指标的动态变化规律，并讨论了它们之间的相互关系。结果表明：白洋淀芦苇（Phragmites australis var．baiyangdiansis）型水陆交错带对营养物质具有强烈的截留作用，可以达到净化白洋淀水体的效果。从水质指标的空间分布看，污染较重的府河河口区域其水体TP、化学需氧量（CODc，）含量明显高于污染较轻的湖泊中心区域，空间梯度上呈逐步递减趋势。根据水体盐度、总溶解性固体、TP及DO含量进行聚类分析，可以将采样点分为3类：Ⅰ区、污染较重河口区域；Ⅱ区、中间过渡缓冲区域；Ⅲ区、污染较轻中心区域。Ⅰ区其水体DO含量明显低于Ⅲ区，而水体盐度则明显高于Ⅲ区。通过调查发现：在8月份，白洋淀水体DO含量突然增加；相关分析表明：叶绿素含量与DO（P=0．046）及温度（P〈0．01）之间呈显著正相关关系。结合叶绿素等指标的动态变化规律，8月份左右可能是白洋淀藻类爆发的危险时期。

Studies on hydrochemical changes and purification effects of the Phragmites australis-dominated land/inland water ecotones in Baiyangdian Lake

To study the mechanisms of wetlands degradation in the eutrophicated Baiyangdian Lake, field surveys had been con-ducted periodically from March to November 2007. The spatial and temporal variations of temperature, dissolved oxygen (DO), chlorophyll, total phosphorus (TP), and other hydrochemical indices were examined along a pollution gradient at a relatively large spatial scale. The relationships between these indices were analyzed. Results indicated that the Phragmites australis-dominated eco-tones in Baiyangdian Lake possessed strong retention capacity on allochthonons nutrients, and could act as buffer zones to protect the lake water. The spatial distributions of water quality indices showed that the contents of TP and chemical oxygen demand (COD_Cr) in the heavily polluted river mouth areas were significantly higher than those in the less polluted central lake areas. Gradual decreasing trends of TP and COD_Cr were found from river mouth areas to central areas. Cluster analysis according to salinity, total dissolved solids, TP and DO, demonstrated that all sampling stations could be divided into 3 categories: Zone Ⅰ, heavily polluted river mouth areas; Zone Ⅱ, the intermediate transitional buffering areas; Zone Ⅲ, less polluted central lake areas. The DO contents of Zone Ⅰ were significantly lower than those of Zone Ⅲ, while the salinity of Zone Ⅰ was significantly higher than that of Zone Ⅲ. Field sur-veys gave evidence of a sudden increase of DO contents in the water column of Baiyangdian Lake in August. Correlation analysis revealed that the DO contents correlated positively with chlorophyll (P=0.046), and chlorophyll was positively correlated to temper-ature (P < 0.01). Based on the changes of chlorophyll, it was suggested that about August might be a critical stage for the outbreak of algal bloom in Baiyangdian Lake because of high temperature and artificial disturbance.