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Volume 54, Issue 1
Displaying 1-9 of 9 articles from this issue
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Fuji MORII, Takeko MATSUMURA-INOUE, Yosimi TANAKA1993 Volume 54 Issue 1 Pages 3-10
Published: January 25, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSConcentrations of eight major inorganic components (Ca2+, Mg2+, Na+, K+, Cl-, SO42-, SiO2 and HCO3-) were measured in water samples from 22 rivers flowing into Lake Biwa. The water quality of these river waters is discussed in relation to the geological environment around their riverhead. The riverhead environment around Lake Biwa was geologically divided into four areas such as granite-, Ko-biwako-, slate- and limestone area.
The amounts of the inorganic components in the river water samples from the four areas decreased in the following order: limestone-> Ko-biwako-> granite-> slate area. The proportion of each component seemed to reflect the geological features of the riverheads: Ca2+ and HCO3- were dominant in the limestone group; SO42- in the Ko- biwako group; Na+ and SiO2 in the granite group, and Mg2+ and Cl- in the slate group.View full abstractDownload PDF (483K) -
Distribution of Groundwater Quality as Indicators of Seepage PatternsMasao KOBAYASHI, Masahiro OZASA1993 Volume 54 Issue 1 Pages 11-25
Published: January 25, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSThe spatial distributions of groundwater quality were investigated at the western shore of Lake Biwa where shallow groundwater near shore contains high CaCl2 concentrations.
Seepage groundwater having high CaCl2 concentrations occurs mainly within an approximate 20m distance from shore. Confined groundwater flows through a low permeable layer and then seeps into the lake offshore. Contour lines of Cl-concentration of interstitial water veer almost vertically upward on the shore side near the inflexion point of the lake bed. The spatial patterns of water quality distribution along the transect are consistent with those of seepage flux observed by seepage meter.
These results indicate that in shallow groundwater seepage into the lake in a narrow zone near shore, groundwater flow is controlled by geometric configuration of the lake bed. Seepage measurements confirm the validity of the direct method of using a seepage meter for observing groundwater flow into the lake.View full abstractDownload PDF (850K) -
Potential Distribution of Groundwater near ShoreMasao KOBAYASHI1993 Volume 54 Issue 1 Pages 27-38
Published: January 25, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSObservations were carried out using a number of piezometers and seepage meters at the western shore of Lake Biwa to investigate the groundwater flow across the lake bed.
Shallow groundwater moves horizontally toward the lake, then the flow veers rapidly upward assuming an arcuate configuration near shore. The flow concentrates in a narrow zone within about 20m from shore. Seepage distributions in the unconfined aquifer show discernible patterns that generally conformed to other field observa-tions. Seepage fluxes on the offshore bottom composed of a low permeable layer show constant distribution. There are also no seasonal changes in these seepage patterns.
Flow nets inferred by the observed equi-potential lines of groundwater are consis-tent with seepage patterns which observed by seepage meter along the same line, and concur with those predicted in published studies.
These results indicate that field observations strongly confirm the usefulness of the direct method and the applicability of the theoretical models for understanding groundwater seepage into the lake.View full abstractDownload PDF (663K) -
Tatsuo MIYAZAKI, Satoshi MIYASHITA1993 Volume 54 Issue 1 Pages 39-48
Published: January 25, 1993
Released on J-STAGE: December 11, 2009
JOURNAL FREE ACCESSWe measured diel changes in neutral sugars, amino acids and fatty acids of particulate matter in Lake Nakanuma in August 1988. We also measured uptake of carbon and nitrogen during the day and night. During the diel cycle, chlorophyll at 1 m varied little. Neutral sugars and glucose at 1 m increased during the day and decreased at night. Amino acids did not show such changes. Carbon uptake at 1 m was 2.06 μg-at C⋅l-1⋅h-1 during the day and almost zero at night. The uptake increase during the day corresponded to the diurnal increase of neutral sugars. Ammonium uptake under light conditions during the day at 1m was 1.84×10-1 μg-at N⋅l-1⋅h-1, whereas the night uptake was 59% of that. The change in ammonium uptake did not necessarily correspond to the amino acid changes. We discuss the. relationship between the biochemical components and uptake activities of phytoplankton.View full abstractDownload PDF (548K) -
Yasuhiro SATOH, Naoki KOIDE, Shigeru OASA, Izumi SUZUKI, Toshitaka SUZ ...1993 Volume 54 Issue 1 Pages 49-58
Published: January 25, 1993
Released on J-STAGE: December 11, 2009
JOURNAL FREE ACCESSThis is the first attempt to elucidate the seasonal changes in some physical and chemical parameters in a water column of Lake Hibara. The observation extended from spring to early winter of 1991.
In the hypolimnion, nitrification started between 13 June and 10 July. The nitrification rate in this period was 0.21-0.44μg atom N⋅1-1⋅day-1. The dissolved oxygen (DO) level of about 0.6-0.7 mg⋅1-1 appeared critical in impeding efficient nitrification. The gross ammonia production rate was estimated to be 0.05-0.15 μg atom N⋅1-1⋅day-1. Denitrification seems to have taken place in the lower hypolimnion and/or on the surface of the bottom sediment when DO decreased to 2-3%(0.2-0.3 mg⋅1-1). The levels of TN, TP, Chl. a and transparency in the autumn circulation period indicate that the lake is on the boundary between oligo- and mesotrophic, though the epilimnetic water in summer was oligotrophic. The relative areal oxygen deficit in the hypolimnion (0.055-0.061mg⋅cm-2⋅day-1) was at the lower limit of eutrophy. The question of why, in spite of the lake's overlying oligotrophic epilimnion, the hypolimnetic DO consumption rate was at a eutrophic level remained to be solved. The hypolimnetic DO consumption rate seems to have been accelerating for the last 20 years. To elucidate the extent of the fluctuation of the hypolimnetic processes from year to year is important for future study.View full abstractDownload PDF (599K) -
Seiichi NOHARA1993 Volume 54 Issue 1 Pages 59-68
Published: January 25, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSA field survey was made of the annual biomass changes of Trapa natans L., a floating-leaved plant, from 1985 to 1986 in a natural stand in Takahamairi Bay of Lake Kasumigaura, Japan. Aerial photographic surveys were done from 1985 to 1990. In addition to the photographs, vegetation maps from 1972 to 1990 were made, based on photographs of 1972, 1976, 1980, 1984. A violent wind during a typhoon in late August 1985 caused a subsequent decrease in the stand of Trapa natans whose maximum biomass was 340 g dry weight m-2 before the typhoon. The stand recovered in 1986 from buried seed and seed generated before the typhoon. Because the plant floats at the end of a long stem, the sudden rise in water level (100 cm) after the typhoon in August 1986 did not cause a subsequent decrease in the stand of Trapa natans wherever strong water current were absent. The violence of winds and water currents during the growing period are important factors in determining the survival of Trapa natans in Lake Kasumigaura. Due to buried seeds and long stem length, the stands of Trapa natans survive in spite of frequent disturbances.View full abstractDownload PDF (614K) -
Tidal, Meteorological and Hydrological Effects on the Water Level Variation in a Lagoon, Lake ShinjiYu ISHITOBI, Hiroshi KAMIYA, Hiroshi ITOGAWA1993 Volume 54 Issue 1 Pages 69-79
Published: January 25, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSThe characteristics of water level variation in Lake Shinji are reported in comparison with the sea level variation at Sakai. Spectral analysis by the fast Fourier transform method, using hourly data of 355 days shows that semi-diurnal and diurnal variations in Lake Shinji are not due to direct water transport from adjacent Lake Nakanoumi through the Ohashi River, but rather to tidal waves damped and distorted through the Ohashi River channel.
This analysis also indicates that water level variations over periods of 4-8 days are predominant in Lake Shinji under low freshwater input, and are similar to the 25-hour moving mean variation of water level at Sakai. The moving mean water level fluctuated following a temporal variation in atmospheric pressure due to the passage of typhoons in the Japan Sea. Hence, the water level variation in Lake Shinji is not determined by the tide, but by meteorological events in combination with the freshwater inflow.View full abstractDownload PDF (565K) -
Masamichi ITO, Kazumi TAGAMI1993 Volume 54 Issue 1 Pages 81-83
Published: January 25, 1993
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSA new species of the genus Isohypsibius collected from municipal water supply of Tsukuba city is described. This species differs from its congeners in having distinct cuticular bars under the inner claws on legs I-III.View full abstractDownload PDF (127K) -
Yasuhiko TEZUKA, Shin-ichi NAKANO1993 Volume 54 Issue 1 Pages 85-90
Published: January 25, 1993
Released on J-STAGE: December 11, 2009
JOURNAL FREE ACCESSLake water collected in mid-August 1991 at a pelagic site in the south basin of Lake Biwa was poured into 2 1 flasks, enriched with various nutrients (control, phosphate, phosphate plus Fe-EDTA, and phosphate plus nitrate), and incubated at 27°C under continuous light (ca. 2, 500 lux) for 26 days in the laboratory.
In all treatments except P+N, Anabaena affinis, which was scarce (50 cells-ml⋅-1) in the original lake water, became predominant, but final cell densities of A. affinis in P and P+Fe-EDTA were several times higher than that in the control. In contrast, several green algae such as Scenedesmus spp., Coelastrum cambricum, C. microporum, Pediastrum duplex and Gloeocystis gigas became predominant in the N+P treatment (at a N: P supply ratio of 20: 1, by weight). These results support the hypothesis that a low nitrogen: phosphorus ratio of lake water is an important factor causing the appearance of Anabaena bloom in the south basin of Lake Biwa.View full abstractDownload PDF (378K)
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