Abstract
Chemical studies of the meltwater discharged from and flowing within a snowpack were conducted. Significant correlation was found between the decreasing pH of the discharged meltwater and the diurnal variation of the anion composition of the meltwater flowing within the sonowpack.
The meltwater discharged from the sonwpack was collected by a lysimeter. Discharge of meltwater was measured by a tipping-bucket gauge and a pulse counter. Conductivity and pH of meltwater were monitored automatically. Periodical samples of meltwater were collected by an automatic water sampler. The first snowmelt of the season was observed on the 14th of March, 1989. In this case, pH of the meltwater decreased quickly from 5.5 to 4.35. After this first melt, snowmelt was not observed for 11 days. On the 28th of March, a second meit occurred, and the decrease of pH was observed again. The pH of meltwater shows the diurnal variations during the active snowmelt period.
The meltwater flowing within the snowpack was collected by a porous cup and vacuum syringe. A trench was dug and a plastic tube with the porous cup was installed in the snowpack horizontally. Meltwater in the snow surrounding the porous cup was collected in the vacuum syringe. The meltwater in the snowpack was collected on the 21st and 24th of April, 1989. It was cold early in the morning of the 21st. The pH of the meltwater discharged from the snowpack decreased about 0.7 during the early melt. On the othre hand, it was not so cold in the morning of the 24th. The decrease in the pH value of meltwater was not so obvious.
When the snowpack was refrozen in the morning, diurnal variation of the anion composition was observed clearly and the depression of pH in meltwater was significant. On the other hand, when the snowpack was not refrozen in the morning, diurnal variation of the anion composition and the depression of pH in meltwater were not so evident.
