Radioactive disequilibrium of thorium series nuclides in surface waters of the Seto Inland Sea

1982 ◽  
Vol 38 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Takashi Okubo
Keyword(s):  
Surface Waters ◽  
Seto Inland Sea ◽  
Radioactive Disequilibrium ◽  
The Seto Inland Sea ◽  
Thorium Series

EVALUATION OF MOUNTAIN AREA AS NON-POINT SOURCE OF NITROGEN FOR SETO INLAND SEA: THE NORTHERN SHIKOKU REGION, JAPAN

2017 ◽  
Author(s):  
Shohei Morisawa ◽  
Shohei Morisawa ◽  
Yukio Komai ◽  
Yukio Komai ◽  
Takao Kunimatsu ◽  
...  
Keyword(s):  
Average Concentration ◽  
Point Sources ◽  
Seto Inland Sea ◽  
Mountain Streams ◽  
Unit Load ◽  
Mountain Areas ◽  
Mountain Area ◽  
The Seto Inland Sea ◽  
Unit Load Method ◽  
Important Position

The northern Shikoku region is located in the Western part of Japan and faces towards the Seto Inland Sea. The forest area, which is one of the non-point sources in the Seto Inland Sea watershed, occupies 75% of the land use in the watershed of the northern Shikoku region. The amount of loadings of nutrients and COD in the Seto Inland Sea has been estimated by the unit load method but actually the data has not been investigated. It is however, necessary to know the real concentration of nitrogen in mountain streams to evaluate the role which is the mountain area plays as non-point sources. Therefore, more water samples of mountain streams in the watershed need to be taken and the concentrations of nitrogen analyzed. The mountain streams in the northern Shikoku area were investigated from April, 2015 to November, 2015. The number of sampling sites was 283, in addition to the past data by Kunimatsu et al. The average concentration of nitrate nitrogen in Ehime, Kagawa, and Tokushima was 0.61mg/L, 0.78mg/L and 0.34mg/L, respectively. The environmental standard range for nitrogen in the Seto Inland Sea is from between less than 0.2mg/L and less than 1mg/L. Therefore, the average concentration of nitrogen in these regions was over category II, and those of mountain streams in Kagawa Prefecture exceeded category III. About 20% of mountain streams were more than 1mg/L. It has become clear that mountain areas occupy an important position as non-point sources for the Seto Inland Sea.

scholarly journals Temporal distribution of primary and secondary production estimated from water quality data in the Seto Inland Sea, Japan

2021 ◽  
Vol 124 ◽  
pp. 107405
Author(s):  
Wataru Nishijima ◽  
Akira Umehara ◽  
Keigo Yamamoto ◽  
Satoshi Asaoka ◽  
Naoki Fujii ◽  
...  
Keyword(s):  
Water Quality ◽  
Secondary Production ◽  
Temporal Distribution ◽  
Seto Inland Sea ◽  
Quality Data ◽  
Water Quality Data ◽  
The Seto Inland Sea
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