RIKEN Accel. Prog. Rep. 50 (2017)

Ⅱ-7. Astrophysics and Astro-Glaciology

Characteristics of Na+ and Cl− distributions in shallow samples froman Antarctic ice core DF01 (Dome Fuji) drilled in 2001: Result ofstrong atmospheric high-pressure blocking events?†Y. Motizuki,∗1 H. Motoyama,∗2 Y. Nakai,∗1 K. Suzuki,∗3 Y. Iizuka,∗4 and K. Takahashi∗1Ice cores record aspects of the geological history ofthe Earth, including past climate changes. Dome Fuji
station, situated in inland Antarctica (77.3◦ S, 39.7◦ E;
3,810m above sea level), is one of the best drilling locations for obtaining ice cores to reconstruct past climates and environments. We present the concentration proﬁles of certain dissolved ions in samples of thepart of a Dome Fuji ice core (DF01) drilled in 2001
that was 7.7m to 65.0m deep.
The anions analyzed were HCOO− , CH3 COO− ,−−−
2−
2−−
CH3 SO−
3 , F , Cl , NO2 , NO3 , SO4 , C2 O4 , and
3−+2++
PO4 , and the cations were Na , K , Mg , Ca2+ ,and NH+
4 . The temporal resolution of the depth proﬁles of the ionic concentrations was about one year(Fig. 1). No signiﬁcant correlations were observed between any ions except for Na+ and Cl− .
The ratios of the averaged ionic concentrations insamples of the ice core diﬀered from the ratios in sea
salt, a result consistent with the ﬁndings of previousstudies. This suggests that the ionic components of thesamples may mainly be of stratospheric origin. Only
several synchronous peaks appear in the concentrations of the Na+ and Cl− proﬁles (Fig. 1).
The Cl− /Na+ ratios of the DF01 ice core samples
analyzed in this study are diﬀerent from those reported
previously for the surface snow at Dome Fuji1) . Thisimplies that Cl− , but not Na+ , was redistributed after deposition2) . High concentrations of SO2−
4 in some
DF01 samples may account for the diﬀerence between
the ice core Cl− /Na+ ratios and the surface snow
Cl− /Na+ ratio.
There were indentiﬁable synchronous peaks of Na+
and Cl− in several samples of the DF01 ice core(Fig. 1). In the samples with synchronous peaks, thecorresponding Cl− /Na+ ratios were conﬁrmed to beclose to the ratio in sea salt (=1.8), indicating the presence of strong sea salt components. This implies thatthe some critical climatic change in the troposphereoccurred to cause precipitation with enhanced sea salt
components to fall in the Dome Fuji area.
Our results suggest that there were, intermittently,
large-scale intrusions of sea salt particles into the interior of Antarctica − the Dome Fuji station is about†∗1
∗2
∗3
∗4

First part of this article was condensed from the paper inGeochemical J., 51, 293 (2017) doi:10.2343/geochemj.2.0458
RIKEN Nishina Center
National Institute of Polar Research, Research Organizationof Information and Systems
Department of Environmental Sciences, Shinshu University
Institute of Low Temperature Science, Hokkaido University- 144 -Fig. 1. Depth proﬁles of Na+ and Cl− of DF01 ice corewith temporal resolution of about 1 year. Synchronous
Na+ and Cl− peaks are shown by arrows; the Cl− /Na+ratios of these samples were conﬁrmed to be close to
the ratio in sea salt.

1000 km from the coast. The intrusion events appear
to have lasted for certain (cumulative) duration thataﬀected one or two of time-resolution periods (Fig. 1).
We conjecture that our analyses could be chemical evidence that the usual Antarctic airﬂow was distorted3)−6)
3–6). High-pressure
High-pressure
by high-pressurehigh-pressure blocking
blockingevents
eventsblocking events convey warm and moist air masses
from the Antarctic coast in the troposphere to inland.
A blocking event at Dome Fuji was observed in 1997 to3,4)
but oneone particularparticular event
event
persist for about a weekweek3),4),, butobserved in 1994 lasted as long as several weeks5) . Ourﬁndings may indicate that several much larger eventsoccurred in the ∼1300-year period investigated in thisstudy. Those events may have been unusually strong
atmospheric high-pressure blocking events.
It is important that the same DF01 samples analyzed for Na+ and Cl− be analyzed for δ 18 O and δD
isotopes, so that the four proﬁles can be compared inorder to conﬁrm that blocking events actually caused
the synchronous ionic peaks in our data.
References
1) e.g., Y. Iizuka et al.: Tellus B 68, 29285 (2016).
2) S. Fujita et al.: J. Glacilology, doi:10.1017/jog.2016.16.
3) N. Hirasawa et al.: Geophys. Res. Lett. 27, 1911 (2000).
4) N. Hirasawa et al.: J. Geophys. Res. 118, 6916 (2013).
5) H. Enomoto et al.: J. Geophys. Res. 103, 23103 (1998).
6) K. Fujita et al.: Geophys. Res. Lett. 33, L18503 (2006).