title: Spatiotemporal distributions of nutrients in the downstream from Gezhouba Dam in Yangtze River, China.
abstract: BACKGROUND
  From December 2008 to November 2009, an investigation of water quality was performed in the 70-km long downstream from Gezhouba Dam in Yangtze River.
  
  
  METHODS
  Twelve sites in all were chosen. Nine parameters of water quality including the total phosphorus, the total nitrogen, chlorophyll a (Chl.a), nitrite, nitrate, ammonia, water temperature, DO, and pH were monitored almost monthly. The multivariate statistical technique (cluster analysis) and the nonparametric method (Kruskal-Wallis Test and Spearman's rank correlation) were applied to evaluate the spatiotemporal variations of water quality data sets.
  
  
  CONCLUSIONS
  According to the Chinese environmental quality standards for surface water (GB3838-2002), the water quality in the river section investigated can attain to the III water standards except total nitrogen. Further analysis indicated that there were no significant spatial differences in these parameters of water quality, but the sampling date had a significant effect. The temporal variation of water quality can be related to the discharge of Gezhouba Dam and moreover be affected by the reservoir regulation. During the discharge, the discharge increased the concentration of total phosphorus and then decreased the N:P ratio, which helps to the occurrence of algae blooms. The high consternation of phosphorus and the low N:P ratio show that the water body can be in the process of eutrophication during the discharge of Gezhouba Dam. In fact, Chl.a had begun to rise in the same period.
authors.affiliation: Key Laboratory of Ecological Effects of Hydraulic Engineering and Restoration of Aquatic Ecosystem of the Ministry of Water Resources, The Institute of Hydroecology, Ministry of Water Resources & Chinese Academy of Sciences, Wuhan, Hubei Province, People's Republic of China. xhujun@gmail.com
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.forename: Ye
authors.initials: Y
authors.lastname: Qiao
authors.forename: Lianfeng
authors.initials: L
authors.lastname: Zhou
authors.forename: Sixin
authors.initials: S
authors.lastname: Li
mesh_terms: D025041:Animal Migration; D000818:Animals; D002681:China; D016000:Cluster Analysis; D003247:Conservation of Natural Resources; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D005068:Eutrophication; D005399:Fishes; D009584:Nitrogen / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry; D011210:Power Plants; D012098:Reproduction / Q000502:physiology; D045483:Rivers / Q000737:chemistry*; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen