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Volume 52, Issue 4
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Kazuhiro KATOH1991 Volume 52 Issue 4 Pages 229-239
Published: October 24, 1991
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSEnvironmental factors affecting the species composition of periphytic diatom assemblages were analyzed in the partly polluted Asa River, in Tokyo, Japan, using principal component analysis, individual differences scaling and direct gradient analysis. The effects of water pollution, seasonal change of temperature, and substrate were detected, among which pollution was the most influential in this river. Substrate had only a little effect. The existence of both direct and indirect effects (through water quality and temperature) was suggested.View full abstractDownload PDF (545K) -
Senichi EBISE1991 Volume 52 Issue 4 Pages 241-253
Published: October 24, 1991
Released on J-STAGE: December 11, 2009
JOURNAL FREE ACCESSThe mountainous area of an upper river is important as the first site of conversion of rainwater to freshwater in a natural state. To study the sharp changes in storm runoff loading on the steep slopes of mountainous watersheds, detailed observations of three small rivers were conducted, including many runoff loading observations during storm events, regular observation of loading during the high flow stage on dry days for riverwater, and observations of annual total loadings of nutrients and pollutants for rainwater. In the mountainous rivers the concentrations and loadings for many water quality indicators under high flow condition increased as the mean value of observed flows increased in each observation year. The fact that the flow-weighted mean concentrations of almost all water quality indicators were higher than their arithmetic means confirmed the high loadings during the high flow stage. Regression equations for total loading during any storm runoff, ΣLgross/A= b⋅(ΣQgross/A)m, for the three rivers were obtained, and high correlation coefficients were noted for total, particulate and dissolved components of many indicators from 13-14 storm events. The exponent, m, in the regression equations for NO3-N, NO2-N, PO4-P and K for the three rivers exceeded 1.0. These analytical results are considered to confirm increases in nutrient and pollutant loading during storm runoff periods.View full abstractDownload PDF (651K) -
Norio OHKUBO, Osami YAGI, Mitsumasa OKADA1991 Volume 52 Issue 4 Pages 255-261
Published: October 24, 1991
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSA field study was carried out from summer to fall in 1988 to clarify the change in the dominant species of Microcystis in Lake Kasumigaura. Microcystis aeruginosa f. aeruginosa and M. aeruginosa f. flos-aquae were dominant in the summer, and M. viridis became dominant in the fall. A high correlation was found between the standing crop of M. aeruginosa and the water temperature, but the standing crop of M. viridis and M. wesenbergii showed no correlation with the water temperature.
Effects of temperature and illumination on the specific growth rates (μ) and the algal yield of M. viridis N-1 and M. viridis NIES 102 were studied with a batch culture. Maximum specific growth rates (μmax) of M. viridis N-1 and M. viridis NIES 102 were observed at 25 and 30°C, respectively. M. viridis could grow at lower temperature than the other species of Microcystis. M. viridis N-1 could not grow under continuous illumination of 2, 000 lx but did so under periodic illumination. The specific growth rate of M. viridis was lower than for other Microcystis species.
These results suggested that M. viridis was more difficult to dominate than other Microcystis in summer.View full abstractDownload PDF (392K) -
Eitaro WADA, John A. LEE, Makoto KIMURA, Isao KOIKE, William S. REEBUR ...1991 Volume 52 Issue 4 Pages 263-281
Published: October 24, 1991
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSThis report is an extended summary of the symposium on "Carbon and Nitrogen Cycles in the Biosphere and Geosphere" in INTECOL '90 held at Yokohama on 28 August 1990. The general ideas and aspects of nitrogen and carbon dynamics in ecosystems are described along with atmospheric nitrogen supply, and behavior of biogenic gases such as carbon dioxide, methane, molecular nitrogen and nitrous oxide.
Increases of the radiatively active gas concentrations (CO2, CH4, and N2, O) in the atmosphere are described in connection with human impacts such as energy requirements and food demand. The increase in atmosheric carbon dioxide has been caused by fossil fuel combustion, that is, a man-made short circuit between atmosphere and C-O-Fe-S cycle. Increase in crop production dominates the fluxes of mineralization processes of organic matter both in aerobic and anaerobic conditions, resulting in the enhancement of methane and nitrous oxide production in the whole biosphere.
Several current efforts to investigate atmosphere-biosphere interactions are schematically summarized for site specific phenomenon such as plant-soil associations and for some representative ecosystems (heathland, rice rhizosphere, tundra and taiga, lake, tropical reservoir, coastal and estuarine system, and global N2O cycle).View full abstractDownload PDF (4382K) -
1991 Volume 52 Issue 4 Pages 283-292
Published: October 24, 1991
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSDownload PDF (669K)
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