LAGUNA LAGUNA 10 p Water quality of Lake Kamo, Sado Island, northeast Japan, Katsuaki Kanzo 1, Ni

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1 LAGUNA LAGUNA 10 p Water quality of Lake Kamo, Sado Island, northeast Japan, Katsuaki Kanzo 1, Niigata Prefectural Ryotsu High School Science Club, Iwao Kobayashi 2 and Masaaki Tateishi 2 Abstract: We have examined the water quality of the Lake Kamo over a 4-year period from August 1997 to August 2001 at 17 observation sites that were set up at 250-m intervals along a N-S line in the lake. Measurements on water temperature, salinity, density, transparency, dissolved oxygen and ph were made at all the observation sites for every depth interval of 50 cm. Thus the data were obtained from a total of 180 measurement points during the entire study period, except on certain stormy days. The data were analyzed and the results are summarized. Key words: Kamo Lake, lagoon, monitoring, natural environment, water quality m cm Fig.1. Map showing the location of the Lake Kamo. 1 2 Niigata Prefectural Sado High School Faculty of Science, Niigata University 47

2 Fig. 2. Bathymetry of Lake Kamo km km 2km 2 9m 5m 260 m 3 4m 30 m 0.9 m sec km 4.2 km 3.8 km ha ,202 10, m 6 9 m m 2E 3 D 4 D 5 D 6 D 7 E 8 E 9 E 10 F 11 G 12 H 13 H 14 H 15 H 16 H 17 H 18 H 17 2 E 4 D 6 D 7 E 9 E 11 G 12 H 14 H 16 H 18 H 10 6 D 11 G 16 H 3 COD 2E 10 F 11 G 13 H 14 H 18 H 18 H 2E mpsu tph YSI-model 85,pH PH TPX-90 i

1997 2001 49 1 Table 1. Observation dates. days on which observations were stopped due to stormy weather; **, days on which water sampling could not be made due to stormy weather.

3 Table 1. Observation dates. days on which observations were stopped due to stormy weather; **, days on which water sampling could not be made due to stormy weather COD NO 2 PO 4 MBAS Fig. 3. Location of observation sites. 17 sites where observations were made for 8 hours aday. 13 sites at which measurements were made for 5 hours in the morning. 10 sites at which measurements were made for 4 hours in the afternoon. 3 sites where COD, NO2, PO4 and MBAS were measured m 50 cm a 5 11 G a a F H 4a

4 50 a d b e c f 4 2 E18 H 10 km abpsu c t d m e fph Fig. 4. Trends in water quality parameters. a, temperature ; b, salinity PSU ; c, densityt ; d, transparency m ; e, dissolved oxygen ; f, ph., average value of the surface measurements;, average value of the bottom measurements;, average of the measured values at all the points between the surface and bottom;, difference in average of surface and bottom values.

5 a 2 4a a 5a psu 32 psu 30 psu 4b 18 H 2E 1psu 4b 1 psu b 30 cm 5b mm 17.8 t 22.5 t 20.8 t 4c 18 H 2E 1 t 4c t 1 5c 5c c mm m 9m 4.5 m 50 4 d 4d 4 5 m e 3 4e 73

6 52 a b d c e 5 11 G a bpsu c t d 30 eph Fig. 5. Temporal changes in the water quality at the observation site 11 G in the central part of the Lake month-year of observation on the horizontal axis; water quality parameter on the vertical axis. a, air and water temperatures, average of the daily maximum and minimum temperatures;, period when the surface water temperature was higher than that of the bottom;, period when the surface water temperature was lower than that of the bottom ; b, salinity PSU ; c, densityt ; d, dissolved oxygen, period when the DO is lower than 30; e, ph., measured value of surface water;, measured value of bottom water;, difference between surface and the bottom.

7 e d ph ph f ph 4f ph ph 4e f ph G 4 6 6a 6c 6b 6d 6e 6f 6g ph 6a psu mm mm 6d 10 psu

8 神蔵勝明新潟県立両津高校理科部小林巖雄立石雅昭 54 a b c d e f g 図 6 湖中央観測点 11 G での時系列等値線図横軸は観測月縦軸は深度 m a 日最高気温 b 水温 c 月別降雨量 mm d 塩分 PSU e 密度 σt f 溶存酸素量と透明度 m g ph. Fig. 6. Time series isometric lines of water quality parameters at observation site 11 G in the central part of the Lake date month of observation on the horizontal axis and water quality parameter on the vertical axis. a, maximum air temperature ; b, water temperature ; c, monthly precipitation mm ; d, salinity PSU ; e, density σt ; f, dissolved oxygen and transparency, m ; g, ph.

9 mm 1.5 m 6d 1.5 m e f mm 1.5 m m m m m COD f 6e m

10 56 ph ph ph ph 6 gph ph pdf http: // pdf pdf pdf pdf pdf ** pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf pdf* pdf pdf pdf* pdf 1998 LAGUNA No.5, A Nguyen Lap Van C 5-34.

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