Water quality and growth of phytoplankton for the Yellow River estuary reservoirs—The nutrients release from reservoir sediments

Effects of nutrients released from sediments on eutrophication in lakes and reservoirs were not well known in China. In the test, the release conditions of nitrogen and phosphorus from the sediments were observed by batch experiment. The test results revealed that the content released is correlated to the initial content of organic matter in sediments. In the Gengjing area, when the water quality of waterway, grit chamber and reservoir were compared, the water quality of the waterway was the highest, and lowered in the order of the grit chamber and the reservoir. The grit chamber could get not only fine sand removal but also the organic substance, nitrogen, phosphorus and phytoplankton, therefore it is important to operate and maintain the grit chamber to preserve the water quality of the reservoir. Due to little organic substance in sediments, ammonium nitrogen and phosphorus weren’t released during the incubation. But from the absorptiometric turbidity unit (ATU) test results, although the release of ammonium concentration was very low, ammonium oxidizing and nitrite oxidizing bacteria existed in sediments.     

Water quality and growth of phytoplankton for the Yellow River estuary reservoirs—The phytoplankton growth potential in reservoirs

In this test,we used phytoplankton assay procedure to carry out determinations of phytoplankton growth potential and limiting nutrients in Gengjing reservoir.The test results revealed that,in Gengying reservoir waters,the phytoplankton growth potential of the autoclaved-filtrates and the filtrates are from 0.2 to 2.1 mg/L and from 0 to 1.0 mg/L,and in waterway waters,those of the autoclaved-filtrates and the filtrates are from 0 to 3.3 mg/L and from 0 to 2.2 mg/L.The phytoplankton growth potential of the autoclaved filtrates is approximately two times higher than those of the filtrates.When phosphorus is adjusted beyond 0.5 mg/L,the growth of the phytoplankton is especially very high.Moreover,the limiting concentration of the phosphorus for the growth of phytoplankton is in the range of 0.025 to 0.05 mg/L;the phytoplankton growth potential of the grit chamber sediment samples is higher than those of the waterway sediment.     

Water quality and growth of phytoplankton for the Yellow River estuary reservoirs—current status of water environment

In this paper,the characteristics of the water quality in Yellow River estuary reservoirs were surveyed and the progress of the eutrophication was investigated by observing the behavior of nitrogen and phosphorus.The results showed that the concentration of dissolved inorganic nitrogen and total nitrogen was very high in all the reservoirs,and the level of nitrogen was eutrophic state.According to Vollenweider’s type model for phosphorus load,the total phosphorus was close to permissible load in Guangnan and Xinan reservoirs.But sometimes,the total phosphorus exceeded an excessive load in Gengjing reservoir.In Yellow River estuary reservoirs,Cyanobacteria,and Diatom phytoplankton were observed mainly,and the cyanobacteria was a the dominant species in summer.