At present, there are few reports on the phytoplankton community characteristics and its relationship with the environmental factors in the sandy river. In this paper, the characteristics of phytoplankton and its relationship were studied taking the Inner Mongolia section of the Yellow River as an object. From the upstream of Inner Mongolia to the downstream 12 sampling sites were set up to carry out an investigation of phytoplankton and the water temperature, dissolved oxygen, total phosphorus and other water quality factors were also synchronally monitored. While the phytoplankton community was analyzed by the diversity index, the similarity index, the non-metric multidimensional scaling (NMDS) was used to study the relationship between the phytoplankton community structure and the environmental factors. The results showed: the phytoplankton species mainly consisted of the bacillariophyta and the chlorophyta phytoplankton from the upstream to the downstream reach of the Inner Mongolia; The biomass of bacillariophyta phytoplankton was dominated, while the density of cyanophyta was dominant; the species number, the density and the biomass of phytoplankton varied obviously along the section, showing a trend of both ends low and the middle high. NMDS analysis furtherly indicated that there were the significant differences in the phytoplankton community structure among the sampling sites from the upstream to the downstream. An analysis combined with the water environment showed that the turbidity (NTU), the suspended matter (SS), COD had a significant effect on the phytoplankton community structure, and thus the effect of the total phosphorus (TP) and the other nutrient factors were weak, which can be closely related to the river terrain and the feature of"less water and more sand".%目前,有关多沙河流中浮游植物群落特征与环境因子关系的研究报道极少.以黄河内蒙古河段为研究对象,研究多沙河流中浮游植物特征及其与环境因子之间的关系.从该河段上游至下游共设置了12个采样点进行浮游植物调查,并同步开展水温、溶解氧、总磷等水质因子的监测.在采用多样性指数、相似性指数等方法分析浮游植物群落特征的同时,也采用了非度量多维尺度法(Non-metric multidimensional scaling,NMDS)研究了浮游植物群落结构变化及其与环境因子的关系.研究结果表明:内蒙古河段从上游至下游,浮游植物种类组成以硅藻门和绿藻门为主;浮游植物生物量以硅藻门占优,而密度以蓝藻门占优;浮游植物物种数、密度与生物量沿程空间变化明显,呈现出两端低中间高的变化趋势.NMDS分析则进一步显示上下游两端的采样点与河段中间采样点浮游植物群落结构存在显著差异,结合水环境因子分析可知浊度(NTU)、悬浮物(SS)、COD对浮游植物群落结构存在显著影响,而总磷(TP)等营养盐因素影响较弱,这可能与黄河内蒙古河段河道地势及"水少沙多"的特征密切相关.
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