Investigation Of Aquatic Ecosystem And Watre Quality Evaluation In Beiyunhe River

Beiyunhe River is the main sewage system of Beijing and Tianjin, which is the crucial river for safetyof water supply and ecological security of Beijing-Tianjin regions. In order to exploit and protect this riverenvironment rationally, we took four times investigations of phytoplankton, zootoplankton, zoobenthos andphysico-chemical factors character of water in Beiyunhe River, and analysed the phytoplankton speciescomposition, density, biomass diversity index and physico-chemical character during2009to2010. Themian results are briefy summarized as follows:1. There are41species of phytoplankton in Beiyunhe River, including14species of Cyanophyta,14species of Chlorophyta,7species of Bacillariophyta,5species of Euglenophyta, and the other two species.Dominated by blue algae in summer, green algae was main species in autumn, winter and spring. Overall, itbelongs to blue algae-green algae type, and the dominant species are Cyanophyta and Chlorophyta whichare species tolerant to pollution, Such as Oscillatoria, Chlorophyta, Entophysalis, Scenedesmus.2. There are79species of zootoplankton in Beiyunhe river, including34species of Rotifers,23species of Cladocera,12species of Protozo,10species of Copepods; Dominated by Rotifers in summer,winter and spring in Beiyunhe river, but it is mainly Protozoa in autumn,the dominant species ofzootoplankton are Rotifers and Cladocera which are species tolerant to pollution, Such as B.calyciflorus,B.rotundiformis, Bosminopsis deitersi.3. There are17species of zoobenthos in Beiyunhe River, including7species of Mollusca,7species ofOligochaeta,3species of Hydrophily insect. The dominant species are Mollusca and Oligochaeta which arespecies tolerant to pollution,such as T.aulodrilus bretscher, B.sowerbyi.4. The water pollution sensitive speciesin Beiyunhe River, including Oscillatoria and Chlorella,Cyclotella of phytoplankton, B.rotundiformis and B.calyciflorus of zootoplankton, T.aulodrilus bretscherand B.sowerbyi of zoobenthos.5. The seasonal variation chlorophyll a in beiyunhe river, the highest in summer and winter, theminimum in autumn. Changes are consistent with the planktonic algae biomass season; The transparency ofthe sample points are lower in beiyunhe river, the highest value of transparency in the summer, the lowestvalue in the autumn; The concentration of dissolved oxygen maximum in spring, winter solution of the concentration of oxygen minimum; The nitrogen to phosphorus ratio below20:1, only the fall of thehighest13.02:1, other seasonal nitrogen and phosphorus than nitrogen limiting nutrient salt in13below,which can be inferred in beiyunhe river.6. The number and types of Benthic are small, the flutter earthworm index evaluation of water quality,very different results with other indicators, it is not suitable to use the the chatter earthworm index toevaluate the water quality in beiyunhe river. The results obtained by the benthic fauna biodiversity indexonly serious water pollution in beiyunhe river, few species can not clearly distinguish the specific degree ofpollution.7. Combination of physicochemieal index, we assessmen the river water quality by phytoplankton,zootoplankton on Shannon-wiener index, the results are: The value of CODMn, NH3-N, NO3-N, TP and TNin Beiyunhe River are2.12-9.79times higher than standards of type V national surface water environmentquality. The total nitrogen, ammonia nitrogen and total phosphorus are major pollutants. TST index showedthat water quality in beiyunhe rivre are eutrophic throughout the year, the overall trend is the highest insummer and autumn, the minimum in winter. In a word, the water quality in Beiyunhe River is generallypoor, most of sections are medium pollution, some sections are heavy pollution, the water quality ismiddle-heavy level.