EVALUATION OF SELF-PURIFICATION EFFICIENCY OF FUHESTREAM-BAIYANGDIAN LAKE THROUGH ZOOPLANKTON

The Fuhe Stream is the majar one for the discharge of wastewater from Baoding City.Itreceives a large amount of domestic sewage and some industrial wastewater from the urbandistricts and then runs into Baiyangdian Lake.To monitor the toxic stress of pollution and the efficiency of self-purification at varioussections of Fuhe Stream-Baiyangdain Lake, investigations into the temporal and spatial variations of zooplankton community structure and function were undertaken in May,July and October,1993.The water quality in Fuhe Stream-Baiyangdain Lake was assessed by qualitative and quantitative analyses of zooplankton community.Six sample stations from the upstream close to pollution source to the downstream into Baiyangdian Lake weredistinguishable in terms of differences in the species richness, PFU colonization rate(a functional parameter),individual abundance,biomass and diversity index.Two sample sites of Wangting and Anzhou located in upstream had poor water quality due to the receiving of agreat deal of sewage which contained high concentrations of BOD,COD,NH4-N and T-P,and this was reflected in the variations of the structural and functional parameters ofzooplankton community,that is,impoverished species richness,low PFU colonization rate,high tolerant population abundance and low diversity index value.Pollution stress was obviously lessened at two stations ie Dongxiangyang and Yangdikou in the middle reaches of Fuhe Stream due to water quality's improvement by showing of a great species restoration.The self-purification was greatly enhanced and water quality was clearly improved at twosample stations,ie Wangjiazai and Zaolinzhuang in the downstream. This was indicated bythe dramatic increase in the number of species, the high PFU colonization rate and the highdiversity index value as well as the decrease in the tolerant population abundance andbiomass,along with the reduction of pollutants.The self-purification in Fuhe Stream plays an important role in protecting water qualityof Baiyangdian Lake. The author presents some constructive suggestions for keeping the stability of self-purification in Fuhe Stream to improve water quality of Baiyangdian Lake.