2006 Fiscal Year Final Research Report Summary
Effects of metal complexing organic compounds on elemental cycles in Lake Biwa, Japan and identification of these compounds.
| Project/Area Number |
16510008
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | The University of Shiga Prefecture |
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Principal Investigator |
MARUO Masahiro The University of Shiga Prefecture, School of Environmental Science, Lecturer, 環境科学部, 講師 (80275156)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Lake Biwa / Inflowing Rivers / Copper Complexing Capacity / Adsorptive Cathodic Stripping Voltammetry / Organic Ligands |
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| Research Abstract |
Copper complexing capacities of freshwaters in Lake Biwa and River Amano that is an inflowing river, were determined by adsorptive cathodic stripping voltammetry using ligand competition. In June 2004, primary production was high and complexing capacities were also high throughout the water column. In August 2004, complexing capacity of the water in epilimnion was low compared with that of hypolimnion. This difference in concentration was caused by mass of discharged water from river flooding or photolysis of organic ligands. Complexing capacities of both layers in October were almost the same as those of water of R. Amano sampled in September. Estimated from the stability of allochthonous organic compounds from rivers which mainly consist of humic substances, increase in complexing capacity in the epilimnion was caused by the production of autochthonous organic compounds in the lake. Free copper ion concentration [Cu^<2+>] was estimated to be always below 10^<-12> moll-1.Organic complexes with copper account for more than 99.9% of total copper.
Fe(II) concentration was also investigated in Lake Biwa and inflowing rivers by using ferrozine-Fe(II) complex formation and column extraction. In Lake Biwa, dissolved Fe(II) showed maximum value in surface water presumably because of photoreduction of Fe(IIII). Dissolved form of Fe(II) accounts for 20-30% of total dissolved Fe. As for Fe(II) in the inflowing rivers, almost all Fe(II) existed as dissolved form. Considering from the Fe(II) concentration and pH, Fe(II) was continuously supplied to the river by discharged water. Investigation of the relationship between Fe(II) and organic compounds that functions as a mediator of photoreduction of Fe(III) is now in progress in the lake.
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Research Products
(5 results)
