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Fundamental Structure in Simultaneous Removal for Phytoplankton and Nutrient Salt in Lakes
Tatsuhiro Seki,Yuuichi Ishii,Toshio Ishii,Kazuo Taki 대한환경공학회 2009 Environmental Engineering Research Vol.14 No.4
The water quality in eutrophic lakes is affected by serious problems, such as abnormal increasing of Cyanobacteria. The purpose of this study was to investigate the possibility of a modified flotation system using a hybrid technique formed by chemical compounds and an electrostatic bridge. Therefore, experiments using the hybrid technique were performed to measure the zeta potential value on the phytoplankton surface and the removal efficiencies of phytoplankton, ammonia nitrogen, nitrate nitrogen and phosphoric acid. The results were as follows: Firstly, the zeta potential of M.aeruginosa was observed to approach charge neutralization due to adhesion of magnesium hydroxide precipitate on the phytoplankton surface in the pH range 10.5 to 11. Secondly, the concentration of chlorophyll-a decreased from about 150 to 20 μg/L, with a maximum removal efficiency of 84% due to coagulation with pH values higher than 10. Thirdly, the NH₄-N concentration was observed to decrease from 0.62 to 0.54 mg-N/L (13%), and the PO₄-P concentration, which is a limiting factor to the formation of algae blooms, decreased from 0.27 to 0.02 mg-P/L (92%). These findings suggest that the modified flotation system can be applied for the purification of the raw water of numerous lakes containing high phytoplankton populations and elevated pH.
Miller-Rushing, Abraham J.,Katsuki, Toshio,Primack, Richard B.,Ishii, Yukio,Lee, Sang Don,Higuchi, Hiroyoshi Botanical Society of America, Inc. (Columbus) * Bu 2007 American journal of botany Vol.94 No.9
<P>Climate change is affecting plant phenology worldwide. Phenological responses vary among species, but it is not clear how responses differ among closely related species. We examined a 25-yr record (1981-2005) of flowering times for 97 trees, representing 17 species and hybrids of cherry (Cerasus sp. or Prunus sp.) grown at Mt. Takao, in Tokyo, Japan. The cherry trees flowered earlier over time, by an average of 5.5 d over the 25-yr study. Earlier flowering was explained largely by a 1.8C increase in February-March mean monthly temperatures. Most species and hybrids flowered 3-5 d earlier for each 1C increase in temperature, but early-flowering taxa flowered as much as 9 d earlier for each 1C increase in temperature. Flowering durations and differences in flowering times among species were greater in warm years than in cold years. Species and individual trees also flowered longer in warm years. These results show that the flowering times of closely related species may change similarly in response to climate change, but that early-flowering species may diverge from the overall trend in a predictable way. Such changes in flowering may affect gene flow and pollination as the length of the flowering season increases.</P>