黄河干流全河段浮游植物群落特征与水质生物评价

为明晰水利工程修建后的黄河干流生态完整性与多样性状况，于2019年春季及秋季对黄河干流自源区至河口全河段浮游植物群落进行了调查.共鉴定浮游植物8门130属350种，春季（229种）和秋季（307种）物种数分别占总物种数的65.43%和87.71%，硅藻门和绿藻门均为两季浮游植物优势门类；春秋两季所有断面浮游植物密度及生物量平均值分别为162.39×10⁴cells/L、2.53mg/L和141.12×10⁴cells/L、3.04mg/L；根据多样性指数进行水质生物评价，秋季整体水质优于春季水质.受水库影响断面的浮游植物密度与生物量均大于临近自然河道断面；多年调节水库和年调节水库浮游植物现存量为库首>库中>库尾，不完全年调节水库则与之相反，日调节水库库区内三个断面差异不大.水质生物评价结果表明，黄河干流自源区至河口的污染程度逐渐增加.

Phytoplankton in the mainstem of the Yellow River: Community characteristics and bioassessment of water quality

The phytoplankton community in the mainstem from the source region to the estuary of the Yellow River was investigated in the spring and autumn of 2019 to understand the effects of water conservancy projects on ecological integrity and diversity. A total of 350 phytoplankton species, which belong to 8 phyla and 130 genera, were identified. The number of species in spring (229 species) and autumn (307 species) accounted for 65.43% and 87.71% of the total species, respectively. Bacillariophyta and Chlorophyta were dominated. The average phytoplankton density was 162.39×10⁴ cells/L for spring and was 141.12×10⁴ cells/L for autumn. The average biomass was 2.53mg/L and 3.04mg/L in spring and autumn, respectively. Biological evaluation of water quality indicated that water quality in autumn was better than that in spring. The phytoplankton density and biomass of the section influenced by dams were greater than the adjacent natural section. The phytoplankton density and biomass decreased from upstream to downstream in the reservoirs regulated every year or for several years. The opposite phenomenon was investigated in the reservoirs not fully regulated. The values from upstream to downstream were not different significantly in the reservoirs regulated daily. The biological evaluation of water quality indicated that the pollution level from the source region to the estuary increased gradually.