Bulletin of Glaciological Research ,0 (,**2) 3ῌ+.
ῌJapanese Society of Snow and Ice

9Chemical dynamics of snowpack in the Northern Japan Alps during snowmelt season
Shailendra Kumar SHAH+, Motoki TANAKA,, Takayuki KURAMOTO+ and Keisuke SUZUKI+, ,+ Correspondence to: Department of Environmental Science, Faculty of Science, Shinshu University, Asahi, Matsumoto, -3*-20,+,
Japan, Correspondence to: Institute of Mountain Science, Shinshu University, Asahi, Matsumoto, -3*-20,+, Japan(Received February ,-, ,**2; Revised manuscript accepted May +., ,**2)

Abstract
A snow pit study was conducted on Mt. Norikura in the Northern Japan Alps from January toApril ,**1 to clarify the chemical dynamics in the snowpack during the snowmelt season. Littlesnowmelt occurred before February 0, the ﬁrst snowmelt occurred between February 0 and ,+, and thepeak of the snowmelt season occurred after March 1. Snow layers with remarkably high Cl῍, NO-῍,and SO.,῍ concentrations in the snowpack were traced; furthermore, the snow layers with high SO.,῍
concentrations were found to disappear ﬁrst. It was concluded that the ease with which the ions wereﬂushed out from the snowpack was SO.,῍῏NO-῍῎Cl῍.

+.

Introduction

In recent years, acid precipitation has been observed all over the world. The e#ects of acidic precipitation on inland water ecosystems across themany lakes of Scandinavia and eastern Canada havebeen reported (Gorham, +30+; Minns, +32+). And thepH of snowmelt water in particular has been reported
to be extremely low. Therefore, it is important tounderstand the behaviors of anions in snowmelt water and the snowpack during the snowmelt season.
Before snowmelt, the concentration of dissolved
ions in the snowpack is the same as that in the snow.
However, these ions ﬂow out with the snowmelt water
during the snowmelt season. The concentration ofthese ions in the snowmelt water is high early in thesnowmelt season, and it lowers as snowmelt progresses (Johannessen and Henriksen, +312; Jones andDeblois, +321). This is explained by the fact that theions in a snow particle are released to the surface ofthe snow particle during the process by which ittransforms into a granular snow particle in the snowpack; this phenomenon is due to the di#erence infreezing point between pure water and water containing dissolved ions. Thus, the snowmelt water thatﬂows over the surface of the snow particle selectively
dissolves the ions, leading to a higher concentration insnowmelt water than in the snowpack (Suzuki, +32,).
Suzuki (+33+) reported that the snow particles that
constitute the snowpack release the ions to their surfaces during melting/refreezing cycles.

Since di#erent ions will separate from snow particles at di#erent rates, there must be a certain orderin which the ions are ﬂushed out of the snowpack;there have been some reports on this phenomenon(Brimblecombe et al., +32/; Iizuka et al., ,***). For example, Suzuki (+33+) measured the daily variation of
the anionic components in snowmelt water; he foundthat when refreeze occurred at the surface of thesnowpack in the early morning, the ratios of SO.,῍
and NO-῍ were high, and by day the ratio of Cl῍ washigh. This results suggested that the order of theease with which ions were ﬂushed was SO.,῍῎NO-῍῏Cl῍. Brimblecombe et al. (+32/) conducted snow pit
work on two consecutive days in Scotland and compared the order in which di#erent ions were ﬂushedfrom the snowpack with the snowmelt. His results
suggested that the order of the ease with which ionswere ﬂushed was SO.,῍῏NO-῍῏NH.ῌ῏Kῌ῏Ca,ῌ῏
Mg,ῌ῏Hῌ῏Naῌ῏Cl῍. Davies et al., (+321) experimentally deﬁned the order of the ﬂush of each ion andreported it as Ca,ῌ῎Mg,ῌ῏SO.,῍῏NO-῍῏Naῌ῏Cl῍.
Thus, each preceding report has indicated di#erent
orders and there is no uniﬁed opinion.
In most of the low-lying areas of Japan, snowmelts are frequent, even in the winter season. Incontrast, in the high mountainous areas of Japan,
snowmelts seldom occur. The chemical substances
in a snowpack burst out intensively during the snowmelt season. In other words, the chemical dynamics inthe snowpack in high mountainous areas during thesnowmelt season are more conspicuous than those in
the low-lying areas. The object of this study is to