Spatial distributions of soluble salts in surface snow of East Antarctica

Figures & data

Fig. 1 Region of study and sampling sites in East Antarctica. The green boundary in the left map shows the location in Antarctica. At right, an enlarged region shows locations of snow samples. Blue marks spots where several tens of centimetres were extracted, and red marks spots where only freshly fallen surface snow was extracted. The base map is from GMT free software.

Table 1. Particle sampling sites, their positions and dates

Sample site	Latitude (°S)	Longitude (°E)	Altitude (m)	Distance from the sea (km)	Sampled date	Top (cm)	Bottom (cm)	Particle measured number (N)	Average diameter (µm)
H15	69.07	40.77	1022	132	23 Nov 2012	0	5	505	0.83
H72	69.20	41.08	1185	167	23 Nov 2012	0	5	456	0.87
Z2	70.04	43.15	1924	406	25 Nov 2012	0	80	195	0.79
Z32	70.25	43.55	2060	453	26 Nov 2012	0	5	348	0.72
Mizuho	70.71	44.27	2215	540	27 Nov 2012	0	50	362	0.81
NMD196	72.51	43.64	2845	537	3 Dec 2012	0	50	373	1.05
MD270	73.17	43.35	3063	553	5 Dec 2012	0	5	255	1.13
MD370	74.06	42.98	3338	567	8 Dec 2012	0	50	361	0.91
MD422	74.52	42.62	3431	573	9 Dec 2012	0	5	369	1.06
MD480	75.05	42.17	3537	585	10 Dec 2012	0	5	503	0.83
MD590	76.03	41.13	3684	621	12 Dec 2012	0	50	383	0.89
MD690	76.93	40.12	3754	681	14 Dec 2012	0	5	434	0.80
Dome Fuji	77.32	39.70	3803	714	13 Jan 2013	0	30	461	0.96
JARE54-024	79.36	40.51	3678	890	28 Dec 2012	0	30	348	0.91
S80E40.5	80.00	40.50	3625	944	3 Jan 2013	0	30	367	0.81

Distance from the sea is measured from Syowa Station (69.00°S, 39.58°E). Also shown are the number of measured particles, particle diameters and depth of snow extracted.

Fig. 2 Elemental distribution of non-volatile particles in surface snow. Each column shows the relative number of particles, at the labelled latitude, having chloride without sodium (light blue), sodium chloride (dark blue), sulphate without sodium (light green), sodium sulphate (dark green) and neither sulphate nor chloride (‘other’, red).

Table 2. Ion concentrations (Cl⁻, , , Na⁺; µmol L⁻¹) and Cl⁻/Na⁺ ratio

Sample site	Altitude (m)	Cl^−			Na^+	Cl^−/Na^+	Na2SO4 (IDM)	NaCl (IDM)
H15	1022	11.50	1.18	1.02	9.69	1.19	1.18	7.33
H72	1185	4.29	0.55	2.25	1.75	2.45	0.55	0.65
Z2	1924	1.61	0.49	0.84	1.21	1.33	0.49	0.23
Z32	2060	0.94	0.57	0.73	0.52	1.80	0.26	0
Mizuho Station	2215	1.40	0.86	1.65	0.83	1.69	0.41	0
NMD196	2845	1.42	0.36	1.29	0.96	1.48	0.36	0.24
MD270	3063	1.54	0.71	2.60	0.83	1.85	0.42	0
MD370	3338	0.76	0.45	1.34	0.32	2.39	0.16	0
MD422	3431	n.a.	n.a.	n.a.	n.a.
MD480	3537	0.57	0.33	2.40	0.14	4.01	0.07	0
MD590	3684	1.73	0.54	1.51	0.95	1.82	0.47	0
MD690	3754	2.06	0.75	1.90	1.24	1.66	0.62	0
Dome Fuji	3803	2.09	0.80	1.29	1.27	1.64	0.64	0
JARE54-024	3678	1.87	0.83	1.29	0.87	2.16	0.43	0
S80E40.5	3625	1.78	0.73	2.11	0.82	2.17	0.41	0

Na₂SO₄ and NaCl (µmol L⁻¹) are from the ion-deducing method (IDM).

Fig. 3 Ternary plots of Na, Cl and S atomic ratios in non-volatile particles by the sublimation–EDS results. Latitude titles are marked as in Table 1. Yellow, purple, blue and green circles in the bottom-right diagram (right of the 80°S plot) denote the atomic ratios of bulk seawater, wholly Cl-depleted sea-salt particles with nitrates, wholly Cl-depleted sea-salt particles with sulphates and wholly Cl-depleted sea-salt particles with methane sulphonates, respectively.

Fig. 4 Number fraction of Na compounds. From the same data as plotted in Fig. 3. Dark blue denotes sea salt. Light blue denotes wholly Cl-depleted sea-salt particles with sulphates and purple denotes partly Cl-depleted sea-salt particles with sulphates. Light green denotes wholly Cl-depleted sea-salt particles with nitrates and brown denotes partly Cl-depleted sea-salt particles with nitrates. The colour order in the data is the same as that in the legend.

Fig. 5 Mole and number ratios of NaCl/Na₂SO₄ along the traverse by the ion-deducing method (IDM) and the sublimation–EDS method. Top plot is logarithmic and also shows the altitude (purple diamonds) along the traverse. The bottom plot is the same, except a normal, linear scale. Non-filled white boxes with coloured frame are for summer snow, whereas the filled coloured boxes mean multiyear snow.