Original functions of the Ca-Mg index correlating positively with phytoplanktonic particulate phosphorus concentration in a reservoir
| Project/Area Number |
02804055
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
生態学
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| Research Institution | Ehime University |
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Principal Investigator |
KAGAWA Hisanori Ehime University, College of Agriculture, Professor, 農学部, 教授 (40003777)
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| Co-Investigator(Kenkyū-buntansha) |
HIROTANI Hiroshi Ehime University, College of Agriculture, Assistant, 農学部, 助手 (70218858)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1991: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1990: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Reservoir / Phytoplankton / Ca-Mg index / Particulate phosphorus |
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| Research Abstract |
The Ca-Mg index, which we proposed previously, consists of an empirical formula 'log(Ca/Mg)-O. 5log(Ca+Mg)' in dissolved calcium (Ca) and magnesium (Mg) in mol concentration, and correlates positively with phytoplanktonic particulate phosphorus concentration (PP) in a log scale at the head of a river reservoir where the river water low in dissolved phosphorus concentration inflows continuously.
A monthly survey of water quality, which began in the Ishitegawa Dam Reservoir in 1984, was continued and in this study the effects of impermeable sheet fences traversing the head of the reservoir at the top 5m of the water column on the availability of the Ca-Mg index were examined preferentially. Little effect was found on the correlation between the Ca-Mg index and logPP. The Ca-Mg index seemed to contain the mixed ratio between river and lake waters in the latter part of the index, -log(Ca+Mg), regardless of the existence of fences, because a significant multiple correlation was found between logPP versus log(Ca/Mg)and volumetric flow rate of inflowing river water in a log scale in addition to the correlation between logPP versus Ca-Mg index.
Unicellular green alga Chlorella vulgaris was cultivated semi-continuously using four kinds of culture media which were low in phosphorus concentration each differing in the Ca-Mg index. Under conditions near the steady state a significant positive correlation was found between the CaMg index and logPP which suggested the existence of a direct physiological function of the Ca-Mg index to the phosphorus nutrition of algae.
In order to make clear the original functions of this empirical CaMg index, the physiological functions of the index, especially of the latter part of the index, -log(Ca+Mg), should be further examined, and a mathematical model, including hydrological factors, of the phosphorus nutrition of algae at the head of reservoir should be developed.
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Report
(3 results)
Research Products
(4 results)
