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Volume 63, Issue 1
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Senichi EBISE, Osamu NAGAFUCHI2002 Volume 63 Issue 1 Pages 1-10
Published: February 28, 2002
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSConcentrations of water quality in streamwater are governed by the path of each runoff component of precipitation and the length of its travel time in that path. Therefore, the combined influence of amounts of rainfall and intervals of rain events govern the concentration of streamwater quality. Yakushima Island is 800 km east of Shanghai and faces to the East China Sea. It has been exposed to acid rain of which the annual mean pH is 4.7, and the annual mean precipitation is about 4300 mm. More than 60 streams from the island's central highland run down radially to the circular shoreline. We have been seasonally observing the water quality of these streams at downstream points and at the five main streams during downflows. The concentration of SO42- on the west and northwest coast streams were always higher than other streams because of acid deposition transported from the East Asian Continent by dominant seasonal winds. The concentrations of almost all chemical components in five main streamwaters ranged from higher values at the upper reaches to lower ones at the lower reaches. The concentrations of pH, alkalinity and electric conductivity have also showed similar characteristics.
Based on the observation data during dry-weather days, there were no remarkable tendencies in either seasonal or yearly changes in water quality in the streams . However, we observed water quality changes during two storm events in the two biggest streams, River Anboh and River Miyanoura, at upstream and downstream points, respectively. Due to the difference in the scales of the two storms and the altitudes of our observation points during the downflow, the changes in the concentrations of water quality components during the two storms differed from each other. Because of its steep topography and thin soil layer, the effects of acid rain on fresh water should be estimated by classifying them into the direct effects over the short term and the indirect effects over on the long term.View full abstractDownload PDF (713K) -
Osamu NAGAFUCHI, Hironori KAKIMOTO, Senichi EBISE, Masao UKITA2002 Volume 63 Issue 1 Pages 11-19
Published: February 28, 2002
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSIn order to evaluate the effects of acid deposition and the function of forests on fresh water environments, mountain stream waters have been monitored on Yakushima Island. The concentrations of SO42-, NO3-, and other anions and cations in the rainwater undergo seasonal change and vary with the level of precipitation. In particular, the pH in rainwater shows a tendency to fall lower in the winter than in the other seasons. The characteristics of water quality in the central area of the island, that is, the high mountainous area, are lower pH and EC, and also lower concentrations of SO42- and NO3-. On the other hand, the water quality of the western part of the island has a distinguishing feature, that is, a low pH and a higher concentration of anions. However, from calculations of the distance index, no difference is shown in the ion constituents of each mountain stream. The watershed of the Kawara streams, which is located in the western part of the island, is covered with one of the most extensive evergreen broad-leaved forest in Japan. The area is very steep with an average incline of 20 degrees from the summit of Mt. Kuniwaridake to the coastline. As to the reasons why higher concentrations of acid substances are found in the stream waters in the western area, the densely growing canopy may play a role in trapping air pollutants, and acid substances deposited on the canopy would be discharged through fall and a stem flow. Therefore, there is a future risk of acidification of the stream waters due to an increase in the acids loaded from the Asian continent on Yakushima Island.View full abstractDownload PDF (544K) -
Shin-ichi ONODERA, Chieko FUJISAKI, Tomohiro NARUOKA, M.D. BIRMANO2002 Volume 63 Issue 1 Pages 21-30
Published: February 28, 2002
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSIn order to clarify the effect of acid rain on the stream water chemistry of mountainous catchments covered by degraded soil in the Setouchi region, we collected water samples of rainfall, soil water, groundwater, spring water and river water as well as making runoff observations in a small experimental catchment located in Takahara city of eastern Hiroshima. The results are summarized as follows: 1) the exchangeable base cation content in soil was extremely low; 2) the strong acid in rainwater was buffered in surface soil by an ion exchange process between base cations and Al3+". After the infiltration of rainfall, pH of water increased. However, the Al concentration in the surface soil indicates soil acidifications; 3) metal ion in the stream water was composed of base cations except for rainfall periods. On the other hand, Al concentration in the stream water increased, and base cation concentration decreased with the rise in stream discharge during rainfall events; 4) H+ concentration was higher at the spring point than farther downstream. Al concentration also showed the same trend as H+, suggesting a greater contribution of groundwater with high pH to the lower stream and acid neutralization by dilution. On the other hand, the increase in Al concentration in stream water during rainfall events indicates acidification by a discharge of acid subsurface water through the surface soil.View full abstractDownload PDF (822K) -
Masatoshi KAWASAKI, Nobuhito OHTE, Kei NAMBU, Satoru HOBARA, Ryota OKA ...2002 Volume 63 Issue 1 Pages 31-45
Published: February 28, 2002
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSThe purpose of this study was to clarify the dynamics of dissolved organic carbon (DOC) in the Kiryu Experimental Forest. The concentration of DOC and the UV absorbance: DOC ratio were measured along the flow path from precipitation to stream water via soil solution and groundwater. The DOC concentration and the UV absorbance: DOC ratio decreased with depth. There was a vertical variation in the rate of the decrease in DOC concentration, which we postulated as resulting from the occurrence of two different mechanisms in the infiltration process. In the upper soil layer, the relationships between DOC and Al and Fe indicated that organically-complexed Al and Fe contributed to decreasing the DOC concentration. In the lower soil layer, no fluctuation in DOC concentration was seen, although the DOC adsorption efficiency seemed to be homogeneous from the upper soil layer to the lower. We postulated that the easily adsorbed DOC fraction had been removed, and that decomposition contributed to decreasing the DOC concentration in the lower soil layer. The DOC concentrations of stream water and groundwater were almost the same, suggesting that the DOC concentration of stream water during the period of baseflow is determined mainly in the unsaturated zone.View full abstractDownload PDF (1097K) -
Kyoko SAKAZAKI, Akihiko YAGI, Tokihide YOKOI, Hisayoshi TERAI2002 Volume 63 Issue 1 Pages 47-57
Published: February 28, 2002
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSIn the Chita Peninsula of Aichi Pref., there are mainly spring waters (red water) and an abundance of red mud produced around the circumference of spring water on the banks of the Uno-ike Pond. An investigation of this spring water (140 cm maximum depth, 1998-1999) revealed that the minimal value of dissolved organic carbon (DOC) appeared at a depth at which it rapidly decreased to 2 mg L-1 or less in vertical distribution of dissolved oxygen. The maximal value of particulate iron (PFe) also appeared in the same layer. Abundant of Leptothrix sp., heterotrophic iron oxidation bacteria observed under microscopic examination, were found in the DOC mininum layer. By a laboratory experiment using this water, the generation of PFe was confirmed to correspond to the decrease in the dissolved iron (DFe) . It was also possible to clearly observe DOC consumption. These observations were also carried out in the red spring waters of Aichi Pref. In the culture experiments, particulate iron production per day (0.61 ng CFU-1 d-1) was measured, and we obtained a heterotrophic iron oxidation bacterium (KK-2: isolated from the Koogetsuin where red water appeared in spring and summer).View full abstractDownload PDF (4575K) -
Tatsunori NAKAGAWA, Manabu FUKUI2002 Volume 63 Issue 1 Pages 59-66
Published: February 28, 2002
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSUsing known 16S ribosomal DNA fragments amplified by PCR from different bacteria, we evaluated the validity of denaturing gradient gel electrophoresis (DGGE) profiling as a quantitative method to estimate the microbial community in freshwater ecosystems. The number of copies as template DNAs was 104-105 in 100μL of 30-cycle PCR reaction to obtain a detectable DGGE band stained with ethidium bromide under transillumina-tion. Moreover, we compared the band abundances on the DGGE profiling with the band mixture of 16S rDNA fragments blended in PCR solution to evaluate whether DGGE band intensities reflect true gene abundance. As the result, the optimum copy number of mixed template DNA fragments was 105 order in 100μL of PCR solution to estimate the accurate the ratio of mixed DNA by PCR-DGGE. As the abundance of one template DNA was more than 86% of total template DNAs in the PCR reaction solution, the difference in the ratio between the abundance of template DNA and that of DGGE band intensity was decreased. These results indicate that it is important to adjust the concentration of template DNA in the PCR reaction solution in order to perform the PCR-DGGE analysis for evaluation of a predominant microorganism in the microbial community.View full abstractDownload PDF (1838K) -
2002 Volume 63 Issue 1 Pages 67-85
Published: February 28, 2002
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSDownload PDF (1243K)
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