1992 Fiscal Year Final Research Report Summary
Effects of Human Impact on the Wetland Ecosystem
| Project/Area Number |
02306002
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Institution | Tokyo University of Fisheries |
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Principal Investigator |
ARUGA Yusho Fac. Fish., Tokyo Univ. Fish.; Professor, 水産学部, 教授 (10017022)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAI Yasuo Nodai Res. inst., Tokyo Univ. Agric.; Professor, 総合研究所, 教授 (40011796)
YAMAGUCHI Yukuya Coll. Liberal Arts, Saitama Univ.; Professor, 教養部, 教授 (70114220)
OTHUKI Akira Fac. Fish., Tokyo Univ. Fish.; Professor, 水産学部, 教授 (30101041)
HUKUSIMA Tukasa Fac. Agric., Tokyo Univ. Agric. Technol.; Assoc. Prof., 農学部, 助教授 (30111420)
OGURA Norio Fac. Agric., Tokyo Univ. Agric. Technol.; Professor, 農学部, 教授 (30015127)
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| Project Period (FY) |
1990 – 1992
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| Keywords | Human impact / Wetland ecosystem / Estuaries / Nutrients / Denitrification / Methane formation / Tidal flat / Desalinization |
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| Research Abstract |
(1) Vegetation distribution maps were prepared around the middle course of River Tamagawa. It was shown that man's influence caused simplification of the floristic composition of plant community and reduced the number of plant communities. The input of COD, N and P into Tokyo Bay in 1989 was estimated to be 300,320 and 26 tons/day, respectively, only 3.8% of which were contributed from River Tamagawa. Denitrification activity at tidal flat of the River Tamagawa estuary was estimated to be 178 mumol/m^2/h in December 1991. LAS were removed completely in summer and about 80% in winter mainly by microbial activities in the River Tamagawa estuary. Organic carbon production and organic nitrogen production by phytoplankton off the River Tamagawa estuary in Tokyo Bay Were estimated to be 1,880 gC/m^2/yr and 281 gN/m^2/yr,respectively. (2) Distributions of the Phragmites community and standing stock and species composition of algae attached to Phragmites were investigated in Lake Kasumigaura.
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In most part of the lake, Phragmites community has been heavily affected and destroyed by shore-protection works. It was found that variations of nitrate and nitrite concentrations in lake water were big in the Phragmites zone but small in the Nymphoides zone, and variations of nitrous oxide concentration in the littoral zone seemed to be coupled with those of nitrate and nitrite concentrations. (3) A study was carried out to clarify the interaction between sulfate reduction and methane formation in brackish water wetland and to identify the sources and mechanisms responsible for the emission of methane into atmosphere. The results showed that the predominance of sulfate reducing reaction may suppress methane formation in brackish water wetland. Lake sediments of Songkhla Lake were surveyed and examined for their possible use to land restoration. It was clarified that the efficient desalinization of heavy clayey deposits is needed, and after desalinization they are dried and can be applied for land as soil dressing materials in degraded areas. Less
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