Phytoplankton Investigation and Water Quality Evaluation in Beiyunhe River
北运河浮游植物调查及水质评价

Beiyunhe River is the main sewage system of Beijing and Tianjin,which is the crucial river for safety of water supply and ecological security of Beijing-Tianjin regions.In order to exploit and protect this river environment rationally,we carried out four times investigations of phytoplankton and physico-chemical factors character of water in Beiyunhe River during 2009 to 2010,and the phytoplankton species composition,density,biomass diversity index and physico-chemical character were also analyzed.The results showed that there were 41 species of phytoplankton in Beiyunhe River,including 14 species of Cyanophyta,14 species of Chlorophyta,7 species of Bacillariophyta,5 species of Euglenophyta,and the other two species.The Beiyunhe River was dominated by blue algae in summer,green algae being the main species in autumn,winter and spring.Overall,this river belongs to blue algae-green algae type,and the dominant species are Cyanophyta and Chlorophyta which are species tolerant to pollution.The value of CODMn,NH3-N,NO3-N,TP and TN in Beiyunhe River was 2.12-9.79 times higher than standards of type V national surface water environment quality.The total nitrogen,ammonia nitrogen and total phosphorus were the major pollutants.Base on our results,we suggest that the water quality in Beiyunhe River is generally poor,most of sections being medium pollution,some sections being heavy pollution,and the water quality is middle-heavy level.