汉江上游平水期浮游植物群落特征及水质生物评价OA北大核心CSTPCD

In this study,we explored phytoplankton community structure and evaluated water quality in the Hanzhong section of Hanjiang River during a normal water period,and identified the primary environ-mental factors affecting phytoplankton.Our aim was to provide a reference for managing the aquatic eco-logical environment in the water conservation area of the upper Hanjiang River.In April 2020,a phyto-plankton investigation was carried out at 15 sampling sites in the Hanzhong section of the Hanjiang River and 11 primary tributaries,focusing on phytoplankton composition,dominant species,density,biomass,and community diversity.Water samples were collected for determination of water physicochemical pa-rameters,including DO,EC,pH,TN,TP,CODMn,and Chl-a.A total of 51 phytoplankton species(vari-ants)from 35 genera and 6 phyla were identified,with absolute dominance by Bacillariophyta(23 species,13 genera)and Chlorophyta(19 species,14 genera),accounting for 45.10％and 37.25％of the total spe-cies.The main dominant species were Cyclotella sp.,Navicula sp.,Synedra acus,Cymbella cistula,Rhab-dogloea sp.,peridinium bipes,Scenedesmus quadricauda,and Cryptomonas ovata.Phytoplankton density and biomass were in the ranges of 0.39×106-3.59×106 cells/L and 0.39-3.49 mg/L,with average values of 1.69×106 cells/L and 1.27 mg/L.There were no significant differences in phytoplankton density or bio-mass between the main stem and tributaries,but biomass in the tributaries was slightly higher.The Shan-non diversity and Pielou evenness indices,with ranges of 0.64-2.15 and 0.28-0.81,were both slightly higher in the tributaries.Water quality in the investigated area was compnsively evaluated by combining physicochemical parameter values,the trophic status index,pollution indicator species,and community di-versity indices.The results indicate that water quality was in transition from slightly polluted to α-meso-saprobic and was slightly eutrophic.The relationship between phytoplankton and environmental factors was examined using redundancy analysis(RDA)and Spearman analysis,and show that TN played a key role in the structure and dynamics of the phytoplankton community in the Hanzhong section of Hanjiang river.Our results provide a scientific reference for assessing aquatic ecology in the Yangtze River basin.