scholarly journals Water problems in Lake Biwa and its catchment area.Biological features of the water quality in Lake Biwa.

1997 ◽  
Vol 26 (8) ◽  
pp. 485-489 ◽  
Author(s):  
Masami NAKANISHI ◽  
Tatsuki SEKINO
1995 ◽  
Vol 31 (11) ◽  
pp. 153-158 ◽  
Author(s):  
M. Kajino ◽  
K. Sakamoto

Musty odor has occurred annually in Lake Biwa since 1969. Osaka municipal waterworks, which is located downstream of Lake Biwa, has made many efforts to treat musty-odor compounds produced in Lake Biwa from spring through autumn. With the development of analytical methods for the determination of musty-odor compounds, we have been able to confirm that planktonic blue-green algae are the major causes of the musty-odor occurrences. The relationship between the growth of blue-green algae and the water quality was not so apparent. However, through our data analysis focusing on the relationship between musty-odor occurrences due to Phormidium tenue or Oscillatoria tenuis and some nutrients in Lake Biwa, we found that the concentration of nitrate in water may be an important parameter for the estimation of growth of the algae and the musty-odor behavior.


1976 ◽  
Vol 12 (1) ◽  
pp. 22-26
Author(s):  
Susumu HASHIMOTO ◽  
Masanori FUJITA ◽  
Kenji FURUKAWA

2002 ◽  
Vol 45 (9) ◽  
pp. 183-193 ◽  
Author(s):  
S. Fujii ◽  
H. Tanaka ◽  
I. Somiya

For the evaluation of pollutants loading to Lake Biwa, comprehensive river surveys on river mouths and forest sites were conducted 9 times from 1996 to 1999, on 25–40 main rivers in the Lake Biwa watershed. The main results obtained are as follows. (1) River water quality reflects regional characteristics of their catchment areas, and the concentration difference among rivers ranged between 2–3 fold. (2) Concentration variation shows different patterns with time and location depending on water quality indices used. (3) Indices related to organic matter and nutrients have lower correlation between forests and river mouths, but those related to ionic species showed strong correlation. (4) Flux comparison of forest and river mouth sites suggests that pollutants from catchment areas are conveyed to the lake not only through rivers but also underground. (5) In dry weather conditions, forests contribute 30% to the whole pollutants (TN, TP, and TCODMn) loading, and the remainder is derived mainly from paddy fields and residential/commercial zones. (6) Unit loading factors from forests are estimated as 640, 57 and 1200 kg/km2/y, respectively for TN, TP and TCODMn, while those from other areas are estimated as 2,500, 208 and 4,200 kg/km2/y.


1998 ◽  
Vol 38 (10) ◽  
pp. 157-163 ◽  
Author(s):  
Atsushi Ichiki ◽  
Toshiyuki Ohnishi ◽  
Kiyoshi Yamada

This study aims to simulate pollutant runoff into Lake Biwa using the Macro Model and examine the runoff characteristics of pollutants from urban nonpoint sources. As a result of the simulations of all rivers flowing into Lake Biwa, the characteristics of urban nonpoint source pollution and the basic units of urban nonpoint pollutants in the Lake Biwa basin became clear. It was shown that the control of pollutant runoff from nonpoint sources during storm events was significant in order to protect the water quality of Lake Biwa. From these results, valuable data concerning the environmental management of the Lake Biwa basin was obtained.


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