Oxygen-18 of snow meltwater and snow cover

Abstract

Chemical studies of the snow meltwater discharged from a snowpack were conducted at Tahima, Fukushima prefecture. Chemical characteristics of precipitation and snow layers were studied.
The snow meltwater discharged from a snowpack was collected by a large lysimeter with an area of 1, 647 m². Discharge of meltwater was measured by a 45° V-notch weir and a pressure gauge. Conductivity of meltwater was monitored automatically. Periodical samples of meltwater were collected by an automatic water sampler. Precipitation was collected by a bulk sampler.
The pH value of precipitation is from 3.89 to 4.36., indicating acidity of snow falls at Tajima. Significant correlation was found between δ¹⁸O of precipitation and mean air temperature. Conductivity of meltwater decreased, and δ¹⁸O of meltwater increased gradually as the snowmelt progressed. The δ¹⁸O of meltwater shows the diurnal variations during the active snowmelting period. The daily peak value of δ¹⁸O is observed in the afternoon.