ADVANCES IN RESEARCH ON NITROGEN RETENTION IN RIVER ECOSYSTEMS

River system was a major transportation channel between land ecosystem and aquatic ecosystem,and river ecosystem normally controls the nutrients output to the downstream by influencing nutrients cycling in the ecosystem.As a major element of eutrophication,nitrogen exists in different forms and concentrations,which are affected by physical,chemical and biological characteristics of river ecosystems,and the natural flow of nitrogen in a river may be disturbed by human activities,which in turn will accelerate eutrophication in rivers.The detailed information of nutrient retention mechanisms,influencing factors and ecological effects of human intervention were reviewed in this paper.With the increase of eutrophication as a major baffle to watershed ecosystem health,further study is needed to examine the effect of nitrogen retention in river ecosystems and corresponding restoration measures.