To investigate the plankton and water quality of Qiantang river, plankton of 12 sampling sites of the study area were monitored in summer 2013. Results revealed that 65 genera of phytoplankton including 37 bio-indicators of pollution and 21 genera of zooplankton were observed. Diversity analysis showed that Shannon-Wiener indexes of phytoplankton and zooplankton were at 1.44 to 2.56 and 1.61 to 2.61, plankton biodiversity integrated index were at 0.419 to 0.558, and water quality integrated index were at 0.303 to 1.43. Data analysis suggested that the water quality of Qiantang river could be sorted from α type to β type of moderate pollution, the pollution degree could be sorted from moderate pollution to slight pollution. The evaluation results by using plankton and physicochemical indexes were consistent.
Long-term trends and spatial patterns of water quality at 5 stations in the upstream of the Daling River basin of North China were examined for 5 parameters—pH, suspended sediment (SS), dissolved oxygen (DO), permanganate demand (CODMn) and biochemical oxygen demand (BOD5). Analysis determined the trends of parameters of each station between 1987 and 2007. The variations in permanganate demand and biochemical oxygen demand showed increasing trends and the variations in dissolved oxygen were decrease in 1990s. Multi-year average values of permanganate demand and dissolved oxygen in Chaoyang station and Jianping station were 2.8 mg/L, 37.6 mg/L and 9.6 mg/L, 6.1 mg/L, respectively. The parameter characteristics of water quality in flood and dry season showed significant heterogeneity at main stream and tributary. Correlations between parameters were analyzed using a regression analysis method. The correlations of each parameter determined there were linear negative correlation between dissolved oxygen and permanganate demand, dissolved oxygen and biochemical oxygen demand at Habaqi station, Dachengzi station and Chaoyang station. The permanganate demand and biochemical oxygen demand was significant positive correlation in 3 stations.
Soils and vegetation of submerged areas will be the endogenous pollutions sources after water storage comes into use in the newly constructed reservoir. Enriched nutrients are released gradually into water, which has an effect on the water quality of reservoir. In this paper, taking Laohutan Reservoir as a study object, accumulation levels of nutrients in soils of the four main types of land use in the reservoir area are studied, the total amount of the pollutants produced by vegetation incineration in the reservoir area is estimated, and based on the experiments the effects of the pollutants in residual vegetation on the water quality of the proposed reservoir are predicted. It provides the theoretical bases for the pollution control of newly constructed reservoir and the establishment of purification measurements before water storage.
In this paper, taking Laohutan reservoir in Huzhou city of Zhejiang province as an example, we systematically discussed the variation trends of trophic status in the early impoundment period of newly built reservoir and the dominant factor of eutrophication. It has been proved that the reservoir’s nutrition index in the early stage is on rise and the water body has a trend of eutrophication. According to actual situation, the outbreak of cyanobacteria and deterioration of water quality in September have showed the features of eutrophication. The dominant factors of eutrophication are total phosphorus, total nitrogen and dissolved oxygen, among which total phosphorus matters most to the trophic status. The results have laid great important foundation for people to explore evolution process of new reservoir ecosystem and the influences of hydraulic engineering construction to ecological environment, and they also provide reference for construction and management of other new reservoir.
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