Investigation Of Phytoplankton,Zooplankton And Evaluation Water Quality In Hanshiqiao Wetland, Beijing

Hanshiqiao wetland locates at the flat land of east Beijing,southwest of Yang town in Shunyi District,which is about 13 km away from Shunyi City and 35 km away from urban district of Beijing,respectively.The conservation area at Hanshiqiao wetland reaches north to Shunpin Road,east to newly built Muyan Road,south to Chaohua Road,involving Yang town,Lisui town and part of Nancai town,with a total area of 1900km~2.Investigation of Phytoplankton,Zooplankton and evaluation water quality in Hanshiqiao wetland,Beijing in 2007revealed:1.Physical and chemical analysis of water quality:Average transparency was 19.0cm.Average TP,TN and CODcr were 0.88mg/L,27.4mg/L and 102.2mg/L, respectively.The 1st point of Hanshiqiao wetland had the lowest transparency and the worst water quality,followed by 2ed,3rd,5th,4th points,which were affected by the influxion of sewage and the ability of sef-purification of the wetland.The average SD at Miyun reservoir,evaluated between April and November in 2007,was 246cm, which was 10 times that of Hanshiqiao wetland.2.Zooplankton analysis:71 kinds of zooplankton were detected,most of which were protozoa and added up to 31 species,accounting for 43.66%of species composition,followed by 29 species of rotifer,accounting for 40.85%;4 species of freshwater cladocer,accounting for 5.63%;7 species of copepods and copepo, accounting for 9.86%.It can be seen that the species composition of zooplankton comprised mainly of protozoa,followed by rotifers,copepods and cladocera,with an average density of 3.98×10~3ind/L.The H value of zooplankton were calculated to be 0.375,using Shannon-Wiener diversity index method.The water quality was obviously eutrophic.3.Phytoplankton analysis:The results showed that the main species of algae phytoplankton were Chlorophyta,Cyanophyta,Euglenophyta,Pyrrophyta,Cryptophyta and Bacillariophyta,with an average density of 2.4×10~8cells/L,of which 55.7%were Cyanophyta.The density of floating algae at Hanshiqiao was relatively_larger but was proportional to the distance from the sewage outlet,that is,the point closer to the outlet possessed the larger density.The H value was calculated to be 0.246 using Shannon-Wiener diversity index method.By aquatic reservoir evaluation criteria, combined with the type and density of zooplankton,it could be clearly determined that the water quality was seriously polluted and eutrophic.4.Comprehensive assessment of water quality:Affected by the influxion of sewage, slow flow velocity,high contents of nitrogen and phosphorus,the quantities of both zooplankton and phytoplankton at 1st point were relatively high,with the appearance of various indicator species of water pollution.Thus,it can be concluded that the water quality of this point was seriously polluted eutrophication,which was also the worst of the five points detected.The dilutive effect of water and cleanup effect of wetland vegetation of 2nd point at east Guanniao Island resulted in low quantities of zooplankton and phytoplankton compared with that of sewage outlet,however,the water quality was still seriously polluted eutrophication determined by comprehensive analysis.With the extension of watercourse,the water quality gradually changed for the better,_but still remained eutrophic overall.