白洋淀水陆交错带对陆源营养物质的截留作用初步研究

Retention of allochthonous nutrients by ecotones or Baiyangdian Lake

在白洋淀进行的野外实验结果表明水陆交错带中的芦苇群落和群落间的小沟都能有效地截留来自府河的陆源营养物质．其中，有植被２９０ｍ长的小沟对地表径流总Ｎ和总Ｐ的截留分别为４２和６５％；４ｍ芦苇根区土壤对地表下径流总Ｎ和总Ｐ的截留率分别为６４和９２％．被截留比率最大的是无机态的正磷酸根态磷和铵态氮．

Field experiments show that reed community and ditches in Baiyangdian Lake ecotonescan effectively retain nutrient elements from land sources. Under moderate hydrologicalcondition, water flows through the ditches and the root zone of reed community. The retention of total nitrogen (TN ) and total phosphorus (TP) by a 300m ditch is measured tobe 42 and 65 % respectively, and that by a 4m distance of reed community soil is respectively 64 and 92%. The retention by reed community mainly happens at the rhizosphere,while the removal of organic matter is less in comparison with inorganic nutrients. Thecomponents retained at the largest ratio are ammonia nitrogen and ortho-phosphate phosphorus. These retention effects play an important role in stabilizing the adjacent ecosystems and reducing the eutrophication of waters.