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Volume 67, Issue 1
Displaying 1-5 of 5 articles from this issue
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Original articles
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Genki I. MATSUMOTO, Yuki AKUTSU, Nobuki TAKAMATSU2006 Volume 67 Issue 1 Pages 1-11
Published: April 20, 2006
Released on J-STAGE: March 21, 2008
JOURNAL FREE ACCESSLake Nishi-Inbanuma (area 680 ha, average depth 1.8 m) in northwest Chiba Prefecture, Japan, is known as a typical eutrophic lake. We studied organic components in the surface sediments (0-5 cm) of the lake to elucidate their features and sources. The lake's high total organic carbon (TOC) contents (3.41-7.18 % with an average of 5.54%) revealed it as a typical eutrophic lake. Normal-alkanes maximizing at n-C29 with a predominance of odd-carbon numbers were detected, together with squalane and UCMH (unresolved complex mixture of hydrocarbons). Stenols and stanols (C27-C29) in the lake sediments originated from plankton and vascular plant debris. Stanols are probably derived from diatoms and dinoflagellates as well as to the influence of a selective degradation and reduction of stenols in the sediments. The contribution of autochthonous organic matter (47.1-72.2 % with an average of 62.8 %) was greater than that of allochthonous organic matter. The latter is mainly supplied from the Shinkawa and Kashimagawa Rivers along with the influence of petroleum products.View full abstractDownload PDF (1141K) -
Tetsuya SANADA, Yoshitaka TANAKA, Hajime YAMAZAKI, Nobuki TAKAMATSU2006 Volume 67 Issue 1 Pages 13-21
Published: April 20, 2006
Released on J-STAGE: March 21, 2008
JOURNAL FREE ACCESSAcid river water samples collected from the Numajiri drainage system, Fukushima Prefecture, Japan, were analyzed for rare earth elements (REE) and major chemical components to elucidate the origin and behavior of REE in the system. The REE concentrations in the samples were observed to decrease downstream due to mixing with other river water and to co-precipitation with Fe and Al hydroxide. Measured REE concentrations were in the range of ng L-1 to μ g L-1, and showed zigzag patterns consistent with the Oddo-Harkins law. Leaching experiments with dilute sulfuric acid solution were performed to study the origin and behavior of REE in the river water. We leached unaltered rock samples collected in the vicinity of an abandoned sulfur mine. The REE patterns of the leachate solutions revealed a striking negative Eu anomaly; this is in contrast to the slightly negative Eu anomaly found in the river water samples. The altered rock showed a positive Eu anomaly. These results indicate that most Eu is derived from acid-resistant minerals in the original rocks, and that some Eu in the water samples comes from a subsequent interaction between altered rocks and acid river waters.View full abstractDownload PDF (666K)
Notes
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Hiroki HAGA, Minako ASHIYA, Taisuke OHTSUKA, Masanari MATSUDA, Akihiro ...2006 Volume 67 Issue 1 Pages 23-27
Published: April 20, 2006
Released on J-STAGE: March 21, 2008
JOURNAL FREE ACCESSThe horizontal distribution of dissolved oxygen (DO) concentrations on the lake bottom was investigated on September 2-5, 2002. At 36 out of the 84 sites, DO concentrations were at less than 50% of saturation. The biomass of macrophytes was investigated on September 6-11 at 44 sites, and ignition loss of sediments was investigated at 41 sites on September 17-18. The results of multiple regression analysis suggested that DO concentrations could be estimated using the biomass of Egeria densa, Myriophyllum spicatum, and Potamogeton maackianus, and the water depth as explanatory variables (R = 0.65, R' = 0.61, n = 44, P < 0.01). Both the partial correlation coefficient and partial regression coefficient indicated that biomass of Egeria densa was the most influential environmental factor on the fluctuation of DO concentrations on the bottom water.View full abstractDownload PDF (431K) -
Satoshi INAGAKI, Taro HIRASAWA, Yoshihisa ITO, Hisayoshi TERAI2006 Volume 67 Issue 1 Pages 29-36
Published: April 20, 2006
Released on J-STAGE: March 21, 2008
JOURNAL FREE ACCESSA system for sewage water treatment in a primary sedimentation pond was investigated using a reactor tank equipped with cylindrical reactors which had porous photocatalyst coated with TiO2 around an ultraviolet lamp. Nitrifying bacteria were inoculated into the reaction tank, and then the time course of POC, DOC, ammonium (NH4+), nitrite (NO2-), and nitrate (NO3-) concentrations in the sewage were observed. The results indicated that the porous photocatalyst exerted the effects on the capture of POC and the absorption and decomposition of DOC. In the reactor tank NH4+ is nitrified to NO3-, which revealed that nitrifying bacteria were active at the inside and/or outside of the cylindrical photocatalyst reactor in spite of ultraviolet radiation. It was also revealed that the porous photocatalyst stimulated ammonium nitrification. By doubling the number of cylindrical photocatalyst reactors in the reaction tank, the nitrification rate was increased, although the POC and DOC were not very affected by the number of reactors.View full abstractDownload PDF (587K)
Limnological record
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Masumi YAMAMURO2006 Volume 67 Issue 1 Pages 37-41
Published: April 20, 2006
Released on J-STAGE: March 21, 2008
JOURNAL FREE ACCESSDownload PDF (491K)
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