Chemical Regime and its Variation in Volcanic Lakes

Chemical regime and its variation in two volcanic lakes, Lake Onneto and Lake Kussharo，Hokkaido were examined by estimating their water and chemical mass budgets. Each of the lakes has ageothermal area in the drainage basin，制作热springs. The chemistry of lake water is thus considered to be controlled by variationsin the discharge and chemistry of hot groundwater originated from the geothermal area. Hydrologicaland limnological observations and water samplings in Onneto and Kussharo performed for aperiod of 26 Aug. to 2 Oct. 1998 and of April 1999 to Feb. 2000，respectively.As a result. Groundwater input to Onneto and Kussharo was estimated at 0.012 to 0.049m D13 D1/s and at 2.96 to 9.43 m m D13 D1/s，respectively.化学mass budget revealed that a seasonal variation in chemistry of chemistryOnneto is dominated by shallow groundwater within the Me-akan Volcano. In order to accurately估计在Kussharo的水购买the hydrological data in the ice-cover period proved to be必要性when the great fluctuation of lake level by surface seiche are neglected。

Chemical regime and its variation in two volcanic lakes, Lake Onneto and Lake Kussharo, Hokkaido were examined by estimating their water and chemical mass budgets. Each of the lakes has a geothermal area in the drainage basin, producing hot springs. The chemistry of lake water is thus considered to be controlled by variations in the discharge and chemistry of hot groundwater originated from the geothermal area. Hydrological and limnological observations and water samplings in Onneto and Kussharo were performed for a period of 26 Aug. to 2 Oct. 1998 and of April 1999 to Feb. 2000, respectively.As a result. Groundwater input to Onneto and Kussharo was estimated at 0.012 to 0.049 mィイD13ィエD1/s and at 2.96 to 9.43 mィイD13ィエD1/s, respectively. Calculation of chemical mass budget revealed that a seasonal variation in chemistry of Onneto is dominated by shallow groundwater within the Me-akan Volcano. In order to accurately estimate the water budget in Kussharo, the hydrological data in the ice-cover period proved to be necessary, when the great fluctuation of lake level by surface seiche are neglected.