# Measurement report: Spatial variations in snowpack ionic chemistry and water stable isotopes across Svalbard

Elena Barbaro, Krystyna Koziol, Mats P Björkman, Carmen P Vega, Christian Zdanowicz, Jean-Charles Gallet, Daniel Kępski, Catherine Larose, Bartlomiej Luks, Florian Tolle, et al.

<figure><img src="image_1.png" /></figure>

To cite this version:

Elena Barbaro, Krystyna Koziol, Mats P Björkman, Carmen P Vega, Christian Zdanowicz, et al. Measurement report: Spatial variations in snowpack ionic chemistry and water stable isotopes across Svalbard. Atmospheric Chemistry and Physics, 2021, 10.5194/acp-2020-740. doi:10.5194/acp-2020-740

HAL Id: hal-03365920

https://hal.science/hal-03365920

Submitted on 5 Oct 2021

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_3.png" /></figure>

1 **Measurement report: Spatial variations in snowpack ionic chemistry and water stable isotopes across Svalbard**

2

3

4 Elena Barbaro¹,², Krystyna Koziol³, Mats P. Björkman⁴, Carmen P. Vega⁵, Christian Zdanowicz⁶, Tonu Martma⁷, Jean-Charles Gallet⁸, Daniel Kępski⁹, Catherine Larose¹⁰, Bartłomiej Luks⁹, Florian Tolle¹¹,

5
6 Thomas V. Schuler¹²,¹³, Aleksander Uszczyk¹⁴ and Andrea Spolaor¹,²*

6 Thomas V. Schuler¹²,¹³, Aleksander Uszczyk¹⁴ and Andrea Spolaor¹,²*

7

8
¹Institute of Polar Sciences, ISP-CNR, Via Torino 155, 30170 Venice Mestre, Italy

9
²Department of Environmental Sciences, Informatics and Statistics, Ca' Foscari University of Venice,

10
Via Torino 155, 30172, Venice, Italy.

11
³Department of Analytical Chemistry, Chemical Faculty, Gdansk University of Technology, G.

12
Narutowicza 11/12, 80-233 Gdańsk, Poland.

13
⁴Department of Earth Sciences, University of Gothenburg, Box 460, SE-40530 Gothenburg, Sweden.

14
⁵Dirección Meteorológica de Chile, Dirección General de Aeronáutica Civil, Portales 3450, Santiago,

15
Chile. *Previously at*: Department of Earth Sciences, Uppsala University, Villavägen 16, Uppsala,

16
Sweden.

17
⁶Department of Earth Sciences, Uppsala University, Villavägen 16, SE-76236, Uppsala, Sweden.

18
⁷Department of Geology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn,

19
Estonia⁸Norwegian Polar Institute, Tromsø, No-9296, Norway

20
⁹Institute of Geophysics, Polish Academy of Sciences, Księcia Janusza 64, 01-452 Warsaw, Poland

21
¹⁰Environmental MicrobialGenomics, Laboratoire Ampère, CNRS, University of Lyon, France

22
¹¹Université de Franche-Comté, Besançon, FEMTO-ST, UMR 6174 CNRS

23
¹²Departement of Geosciences, University of Oslo, Oslo, Norway

24
¹³Arctic Geophysics, University Center on Svalbard, UNIS, Longyearbyen, Svalbard, Norway

25
¹⁴University of Silesia in Katowice, Faculty of Natural Sciences, Będzińska 60, 41-200 Sosnowiec,

26
Poland

27

28
*Corresponding author

29
Andrea Spolaor (andrea.spolaor@cnr.it)

30
**Keywords**

31
Snow, Svalbard, Arctic, inorganic ions, water isotopes

32

33

34

35
<figure><img src="image_4.png" /></figure>

<figure><img src="image_5.png" /></figure>

36 Abstract

The Svalbard archipelago, between 74° and 81° N, is ~60% covered by glaciers and located at the Arctic sea ice edge. The region experiences rapid variations in atmospheric flow during the snow season (from late September to May) and can be affected by air advected both from lower and higher latitudes, which likely impact the chemical composition of snowfall. While long-term changes in Svalbard snow chemistry have been documented in ice cores drilled from two high-elevation glaciers, the spatial variability of the snowpack composition across Svalbard is comparatively poorly understood. Here, we report the results of the most comprehensive seasonal snow chemistry survey to date, carried out in April 2016 across 22 sites on 7 glaciers across the archipelago. At each glacier, three snow pits were sampled along altitudinal profiles and the collected samples were analysed for major ions ($Ca^{2+}$, $K^+$, $Na^+$, $Mg^{2+}$, $NH_4^+$, $SO_4^{2-}$, $Br^-$, $Cl^-$ and $NO_3^-$) and stable water isotopes ($\delta^{18}O$, $\delta^{2}H$). The main aims were to investigate the natural and anthropogenic processes influencing the snowpack and to better understand the influence of atmospheric aerosol transport and deposition patterns on the snow chemical composition. The snow deposited in the southern region of Svalbard was characterized by the highest total ionic loads, mainly attributed to sea salt particles. Both $NO_3^-$ and $NH_4^+$ in the seasonal snowpack reflected secondary aerosol formation and post-depositional changes, resulting in very different spatial deposition patterns: $NO_3^-$ had its highest loading in northwestern Spitsbergen, and $NH_4^+$ in the southwest. The $Br^-$ enrichment in snow was highest in northeastern glacier sites closest to areas of extensive sea ice coverage. Spatial correlation patterns between $Na^+$ and $\delta^{18}O$ suggest that the influence of long-range transport of aerosols on snow chemistry is proportionally greater above 600-700 m a.s.l.

56

57 1. Introduction

Svalbard is a region of the Arctic experiencing rapid climate change, with a mean warming rate of +1.35 K per decade, much faster than the global average (Isaksen et al., 2016; Maturilli et al., 2013; Nordli et al., 2014). This archipelago is located at the southern edge of the perennial Arctic sea ice, in the North Atlantic Ocean, and is characterized by a maritime climate with large, rapid temperature variations during winter (Brage et al., 2014). South-westerly inflow of mild oceanic air, associated with a low-pressure system east of Iceland, often brings relatively warm and moist air in winter months, while Arctic air intrusions from the north-east, driven by a high-pressure system over Greenland, result in much colder temperatures (Rinke et al., 2017). In addition to these synoptic fluctuations, intense autumn or winter cyclonic storms associated with anomalous warming events sometimes occur, transporting both heat and moisture from lower latitudes to Svalbard (Rinke et al., 2017).

68

The aforementioned meteorological conditions also favor long-range transport of aerosols to the archipelago, including pollutants from continental sources. Depending on the predominant air flow pattern at the time of snowfall, the archipelago may experience regionally different amounts of both snow accumulation (Eneroth et al., 2003; Forland et al., 2011) and chemical loads, the latter reflecting
<figure><img src="image_6.png" /></figure>

73 contrasting mixtures of aerosol, varying by source area (Aas et al., 2016; Forsström et al., 2009; Möller and Kohler, 2018). These regional differences are also associated with contrasts in sea ice cover. While 74 all Svalbard coasts are usually ice-free in summer, sea ice can form and cover large parts of the ocean 75 surface in the eastern and northern parts of the archipelago, while the southern and western parts often 76 remain ice-free (Dahlke et al., 2020), and therefore tend to experience greater snowfall owing to the 77 proximity of open water. In addition, the West Spitsbergen Current, a branch of the Atlantic Meridional 78 Overturning Circulation (AMOC) that flows to the west of the archipelago, causes markedly different 79 regional climatic conditions between its eastern and western parts (van Pelt et al., 2019): the west 80 exhibits higher temperatures and precipitation, while the east is less humid and cooler, and has also 81 experienced a stronger warming trend since 1957. 82

83
84 The seasonal snowpack contains a complex mixture of impurities that are either scavenged from the
85 atmosphere during snowfall or directly received through dry deposition (Kuhn, 2001). On land, the
86 majority of impurities found in seasonal snow are usually eluted during summer melting, influencing
87 terrestrial and aquatic systems (Björkman et al., 2014; Brimblecombe et al., 1987). However, in the
88 accumulation area of Arctic glaciers and ice caps, impurities can be retained within or below the seasonal
89 snow layer (Björkman et al., 2014; Pohjola et al., 2002; Vega et al., 2015b). For this reason, chemical
90 impurities such as major ions ($Ca^{2+}$, $K^+$, $Na^{2+}$, $Mg^{2+}$, $NH_4^+$, $SO_4^{2-}$, $Br^-$, $Cl^-$ and $NO_3^-$) in ice cores have
91 been widely used to study past trends of atmospheric and climatic conditions (Barbante et al., 2017;
92 Isaksson et al., 2003; Thompson et al., 2002; Wolff et al., 2010). Previous studies in Svalbard (Goto-
93 Azuma et al., 1994; Nawrot et al., 2016; Semb et al., 1984; Winther et al., 2003) have shown that the
94 chemistry of the seasonal snowpack is dominated by sea salt ions (Hodgkins and Tranter, 2017).
95 However, the region is also a sink for atmospheric contaminants brought in by long-range transport
96 (Vecchiato et al., 2018). Investigations of precipitation and snow cover chemistry have predominantly
97 focused on the central and western parts of the archipelago (Kühnel et al., 2011; Nawrot et al., 2016;
98 Vega et al., 2015a; Virkkunen et al., 2007), due to the accessibility of research facilities in these sectors.
99

100 In the present study, the concentration, mass loading, spatial and altitudinal distribution of major ion
101 species ($Ca^{2+}$, $K^+$, $Na^{2+}$, $Mg^{2+}$, $NH_4^+$, $SO_4^{2-}$, $Br^-$, $Cl^-$ and $NO_3^-$) in snow, together with its stable oxygen
102 and hydrogen isotope composition ($\delta^{18}$O and $\delta^{2}$H), were evaluated in the late winter snowpack at 22
103 glacier sites across Svalbard. This study was part of the larger Community Coordinated Snow Study in
104 Svalbard (C2S3) project and the most comprehensive survey of seasonal snow chemistry in Svalbard to
105 date. The snowpack survey, which was carried out by coordinated teams using a standardized sampling
106 protocol (Gallet et al., 2018) aimed to map and characterize regional differences in the chemical
107 composition and impurity load of the winter snow pack, and interpret the observed differences in relation
108 to meteorological and other environmental factors. In this way, we aim to identify the conditions
<figure><img src="image_7.png" /></figure>

109 controlling the chemistry of Svalbard snow that are susceptible to be influenced by future climate
110 warming across the region.

111

112 **2. Methods**

113 **2.1 Sampling location and strategy**

114 During April 2016, the seasonal snowpack was sampled at 22 sites on seven glaciers across Svalbard:
115 Austfonna (AF) on Nordaustlandet, Lomonosovfonna (LF) on central Spitsbergen, Hansbreen (HB) and
116 Werenskiöldbreen (WB) in the Hornsund area of southern Spitsbergen, and Austre Lovénbreen (ALB),
117 Kongsvegen (KVG) and Holtedahlfonna (HDF) in the vicinity of Ny-Ålesund on northwestern
118 Spitsbergen (Table 1 and Figure 1). The glaciers are of different sizes and hypsometries. Each glacier
119 was sampled in the ablation zone, close to the equilibrium line altitude (ELA), and in the accumulation
120 zone (Table 1). The ELA is the elevation at which the surface mass balance is zero, i.e., where the
121 accumulation of snow is exactly balanced by ablation over a period of a year (Cogley et al., 2011).

122 Although the exact elevation range of these zones differ for each glacier, they share enough glaciological
123 similarities to support inter-site comparisons. Snowpit sampling was performed using a standardized
124 common protocol (Gallet et al., 2018) with pre-cleaned equipment (i.e., tubes, plastic scrapers and plastic
125 shovels cleaned with ultrapure water) and protective clothing (powder-free plastic gloves, clean suits and
126 face masks). Samples for ionic chemistry were taken in each discrete snow pit layer, according to the
127 visible stratigraphy, and directly into pre-cleaned, 50 mL polypropylene "Falcon" centrifuge tubes.

128 Samples for the isotopic composition of water were collected at a 5-cm resolution for sites in the Ny-
129 Ålesund area and at a 10-cm or stratigraphic layer resolution for other sites. All sampling was conducted
130 in a safe distance and upwind from potential local pollution sources, such as the snowmobiles used as
131 transport by the sampling team.

132

133 **2.2 Major ion analyses**

134 Samples from glaciers in the Hornsund region (HB, WB) were analysed at the Polish Polar Station
135 Hornsund (Institute of Geophysics, Polish Academy of Sciences), while samples from glaciers near Ny-
136 Ålesund (KVG, ALB, HDF) were shipped frozen to the Institute of Polar Sciences (ISP-CNR) in Venice
137 (Italy). Snow sampled in central Spitsbergen (AF, LF) was shipped frozen to the Department of Earth
138 Sciences at Uppsala University (Sweden). Due to a temporary equipment malfunction in Uppsala, only
139 cations could be analysed there, and the refrozen samples were forwarded to ISP-CNR for anion analysis.

140 All samples and standards were handled and prepared under clean room conditions, wearing powder-free
141 gloves. In all labs except at the Polish Polar Station Hornsund, laminar flow hoods (class 100) were used.
142 Samples were melted immediately before analysis.

143

144 **2.2.1. Hornsund**
<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

145 Samples were filtered through 0.45 µm mixed cellulose esters membranes (Merck Millipore S-pak®) prior to analysis. Ion concentrations were determined on a Metrohm 761 Compact IC ion chromatograph 146 equipped with an autosampler (Metrohm, Herisau, Switzerland), with isocratic flow, and chemical 147 suppression for anions (column Metrosep A Supp S + Metrosep A Supp 4/5 Guard 4.0, eluent: NaHCO₃ 148 1.0 mmol L⁻¹ + Na₂CO₃ 3.2 mmol L⁻¹). Cations were determined without suppression (column Metrosep 149 C4 + Metrosep C4 Guard; eluent: HNO₃ 1.7 mmol L⁻¹ + 2,6-pyridinecarboxylic acid [dipicolinic acid, or 150 DPA] 0.7 mmol L⁻¹). Cation samples were acidified with 2 µL of 2mM HNO₃ per 10 mL sample prior to 151 analysis, as recommended for this device and column. The injection volume was 20 µL in the anion 152 system and 100 µL in the cation system. Nitric acid solutions were prepared from POCH S.A. (Poland) 153 concentrated weighed amounts, while sodium carbonate and hydrogen carbonate, as well as DPA, were 154 dissolved from solid phase (Merck Millipore). 155

156

### 2.2.2 Uppsala

158 Samples were filtered using 0.22 µm polyethersulfone membranes (Minisart®, Sartorius) and anion 159 determinations were performed using a Metrohm ProfIC850 ion chromatograph (Metrohm, Herisau, 160 Switzerland), equipped with an autosampler and a Metrosep C4 column. The mobile phase of 0.02 M 161 DPA and 0.1 M HNO₃ was run in isocratic flow of 0.7 mL min⁻¹. Very low detection limits (≤ 0.006 mg⁻¹) 162 ¹L) were achieved thanks to the sample injection volume of 500 µL. 163

164

### 2.2.3. Venice

165 Anion determination was performed using a Dionex™ ICS-5000 ion chromatograph 166 (ThermoScientific™, Waltham, US) equipped with an anionic exchange column (Dionex IonPac AS 11, 167 2 × 250 mm) and a guard column (Dionex IonPac AG11 2 × 50 mm). Sodium hydroxide (NaOH), used 168 as a mobile phase, was produced by an eluent generator (Dionex ICS 5000EG, Thermo Scientific). The 169 injection volume was 100 µL. The IC was coupled to a single quadrupole mass spectrometer (MSQ 170 Plus™, Thermo Scientific™) with an electrospray source (ESI) that operated in negative mode. To 171 determine cations, a capillary ion chromatograph (Thermo Scientific Dionex ICS-5000), equipped with a 172 capillary cation exchange column (DionexIonPac CS19-4µm, 0.4 × 250 mm) and a guard column 173 (Dionex IonPac CG19-4µm, 0.4 × 50 mm), was used, coupled to a conductivity detector. The injection 174 volume was 0.4 µL. All details about the anion and cation methods are reported by (Barbaro et al., 2017). 175

176

### 2.2.4. Instrumental performance of each laboratory

177 For all laboratories, calibration for ions were evaluated using analytical standards (Merck/Sigma 178 Aldrich). The calibrations in each lab gave different linear ranges for each ion due to the different 179 methods used (Table S1). Good linearity was demonstrated in each lab and all calibration curves had 180 R²>0.99. Samples that had ion concentrations beyond the calibration range were diluted with ultrapure 181 water before re-analysis. Analytical blanks of ultrapure water (>18 MΩ·cm) were included in the
<figure><img src="image_10.png" /></figure>

182 analysis at all three labs. The method detection limit (MDL) was set to three times the standard deviation of the blank values (Table S1). For Na⁺, Mg²⁺, Cl⁻ and SO₄²⁻, values <MDL occurred in less than 10% of cases, and for Ca²⁺ and NO₃⁻ the <MDL concentrations were noted in 12% and 17% of cases, respectively. However, K⁺ and Br⁻ were detected only in 53% and 46% of all samples, respectively, while NH₄⁺ concentration exceeded the MDL only in 36% of all measurements. For the calculation of bulk ionic loading in snow pits, values <MDL were assumed to be equal to half the MDL.

188
189 Accuracy and precision are important parameters to evaluate during method validation. Checks for accuracy were made using certified multi-element standard solutions for anions (F⁻, Cl⁻, Br⁻, NO₃⁻, SO₄²⁻, n° 89886-50ML-F, Sigma Aldrich) and cations (Na⁺, K⁺, Mg²⁺, Ca²⁺, n° 89316-50ML-F, Sigma Aldrich), at the concentration of 10 mg L⁻¹ ± 0.2%. Accuracy is expressed as a relative error calculated as (Q–T)/T×100, where Q is the determined value and T is the “true” value. The accuracy for each ion in all labs was always <±10%, except for Mg²⁺ measurements at the Hornsund laboratory. The analytical precision was quantified as the relative standard deviation (RSD) for replicates (n>3) of standard solutions and was always <10% for each ion (Table S1).

197
198
**2.3. Stable water isotopes**

199 The determination of stable isotope ratios of O and H was performed at Tallinn University of Technology using a Picarro L2120-i water isotope analyser with a high-precision AO211 vaporizer. Results are reported in the standard delta notation as δ¹⁸O and δ²H relative to VSMOW. Reproducibility was ±0.1‰ for δ¹⁸O and ±1‰ for δ²H, respectively.

203
<figure><img src="image_11.png" /></figure>

<figure><img src="image_12.png" /></figure>

204 **3. Results**

205 **3.1 Spatial distribution of ionic species**

206 To investigate differences in snowpack composition across all glaciers, we compared the total mass of
207 ions that accumulated in snow at the different sampling sites. On average, the snow cover season on
208 Svalbard lasts from early September to early May, but snow may also fall in summer months at high
209 elevations. The snow pits in this study were sampled in early to late April 2016 and might therefore not
210 contain the full annual ionic burden, since deposition might occur also in other months. Therefore, we
211 report these data as ionic loads (mg m⁻²) rather than annual fluxes. In each snow pit, the ionic load was
212 calculated as the cumulative sum of the ionic concentrations multiplied by the snow water equivalent in
213 each discrete layer. The snowpack chemical characteristics were then compared between glacier zones
214 (ablation zone, ELA, and accumulation zone; Table 2, Figure 1).

215
216 Snow pits samples collected in the Hornsund area (southern Spitsbergen) showed a markedly higher total
217 load for all major ions (Figures 1 and 2) than at all other sites. The samples collected in the accumulation
218 zones of WB and HB had total ionic loads of 8161 and 8023 mg m⁻², respectively, four times higher than
219 those collected in the same zone at KVG (2861 mg m⁻²), AF (2607 mg m⁻²) and ALB (1934 mg m⁻²) and
220 16 times higher than those sampled at LF (639 mg m⁻²) and HDF (583 mg m⁻²). Similar differences were
221 observed for the snow pits collected at lower altitudes (Figure 2).

222
223 In the accumulation zone of all glaciers (Figure S1), Na⁺ and Cl⁻ were generally the most abundant ionic
224 species, with percentages ranging from 29% (HDF) to 36% (AF) for Na⁺, and from 34% (LF) to 48%
225 (HB and WB) for Cl⁻, respectively. The snowpack on Hornsund glaciers (HB, WB) had higher Cl⁻
226 percentages (48-49%) compared to that of other glaciers (34-39%), while conversely the SO₄²⁻ percentage
227 was lower there (9%) than on other glaciers (11-23%). The ionic loads were generally highest in the
228 accumulation zone of glaciers, and lowest in the ablation zone (Figure 2), mostly due to the lower snow
229 accumulation and greater wind deflation at lower elevations. This pattern held true for Na⁺, Cl⁻, NH₄⁺,
230 K⁺, Ca²⁺, and Mg²⁺ at most glacier sites, except in the Hornsund region. The load of Br⁻ was similar on
231 glaciers of the Ny-Ålesund sector (ALB, HDF, KVG) and on LF, but was higher in AF and Hornsund
232 glaciers (HB, WB; Figure 2). The load of NO₃⁻ was similar for all glaciers, except for LF, where very low
233 loads were found. Unlike total SO₄²⁻, the non-sea-salt fraction of sulphate (nss-SO₄²⁻), calculated using a
234 seawater SO₄²⁻:Na⁺ mass ratio of 0.252, (Millero et al., 2008) showed lower loads on Hornsund glaciers
235 (15-107 mg m⁻²) when compared to glaciers in other parts of the archipelago (Figure 1, Table 2). The
236 nss-SO₄²⁻ loads varied between 22-131 mg m⁻² at HDF and LF, 75-266 mg m⁻² at KVG and ALB, and
237 153-206 mg m⁻² at AF.

238
239 **3.2 Stable water isotopes (δ¹⁸O and δ²H)**
<figure><img src="image_13.png" /></figure>

Our results provide the first picture of spatial variations in the mean stable water isotope composition of the seasonal snowpack across Svalbard (Table 2, Figure S2). The snow water equivalent (SWE)-weighted mean δ¹⁸O and δ²H decreased significantly from south to north (Spearman rank correlation ρ with latitude was -0.69 and -0.65 for δ¹⁸O and δ²H, with p<0.001 and p<0.01, respectively). The isotopically heaviest snow (least negative δ values) occurred on glaciers of the Hornsund region (δ¹⁸O: -11.25 to -9.54 ‰; δ²H: -77.62 to -63.64 ‰), and the isotopically lightest (most negative δ values) in AF (δ¹⁸O: -16.00 to -13.89 ‰; δ²H: -111.15 to -96.89 ‰). Glacier sites in NW Spitsbergen and on LF had mean δ¹⁸O and δ²H values that fell within these ranges. On KVG, ALB, HDF and LF, the δ¹⁸O and δ²H in snow decreased monotonically (becoming gradually more negative) with increasing elevation. However, on other glaciers this pattern did not hold: on AF, we found an increase from AF1 to AF2, but a decrease from AF2 to AF3; on WB the δ¹⁸O and δ²H were similar at WB1 and WB2, but less negative at WB3. On HB there was no statistical difference between the mean δ¹⁸O and δ²H value in all snow pits. A general, significant anticorrelation with altitude was found for SWE-weighted mean δ²H (ρ= -0.63, p<0.01), and δ¹⁸O (ρ= -0.65, p<0.01).

254

## 4. Discussion

255

There have been few published studies on recent seasonal snow or firn chemistry in Svalbard, hence comparisons of our data with these earlier results are limited to a few sites. (Virkkunen et al., 2007) and (Vega et al., 2015a) and unpublished data) quantified the annual chemical loads of Na⁺, Ca²⁺, NO₃⁻ and nss-SO₄²⁻ at Lomonosovfonna summit (LF3) from 2002 to 2011 using snow and firn cores, and our study extends these data to 2016. The range of annual ionic loads at LF3 over the 15-year period is remarkably wide, but no clear temporal trend can be identified (Table 3). At Holtedahlfonna summit (HDF3), firn core measurements by (Spolaor et al., 2013) found a mean Na⁺ concentration of 110 ±73 ng g⁻¹ over the period 2003-2012, while the mean concentration in the April 2016 snowpack (this study) was 191 ng g⁻¹, hence within the range reported in earlier years.

266

### 4.1 The main ion sources in the Svalbard seasonal snow

The composition of the Svalbard seasonal snowpack sampled during the C2S3 project clearly indicates that the ocean is the main source of ions in snow, as was shown by Hodgkins and Tranter (2017). At all sites, the dominant ions are Na⁺, Cl⁻, and SO₄²⁻, with comparatively minor amounts of K⁺, Ca²⁺ and Mg²⁺ (Figure S1). To help clarify the possible sources and modes of deposition of ions in snow, we computed Spearman rank correlations between total ionic loads (ρload), as well as between volume-weighted mean ionic concentrations (ρconc), across all snow pits (n = 22; Table 4). The chemical species that are predominantly wet-deposited and sharing common sources and not undergoing significant composition changes in transport should exhibit similar concentration patterns (high ρconc) (Schüpbach et al., 2018). The concentrations of Mg²⁺, K⁺ and Ca²⁺ were all positively correlated with those of Na⁺ and Cl⁻,

269

The dominant ions are Na⁺, Cl⁻, and SO₄²⁻, with comparatively minor amounts of K⁺, Ca²⁺ and Mg²⁺ (Figure S1). To help clarify the possible sources and modes of deposition of ions in snow, we computed Spearman rank correlations between total ionic loads (ρload), as well as between volume-weighted mean ionic concentrations (ρconc), across all snow pits (n = 22; Table 4). The chemical species that are predominantly wet-deposited and sharing common sources and not undergoing significant composition changes in transport should exhibit similar concentration patterns (high ρconc) (Schüpbach et al., 2018). The concentrations of Mg²⁺, K⁺ and Ca²⁺ were all positively correlated with those of Na⁺ and Cl⁻,

271
272
273
274
275
276
276
<figure><img src="image_14.png" /></figure>

277 indicating a common sea spray source. The $\rho_{load}$ correlations are very similar for these ionic species, which points to both wet and dry deposition being a significant mechanism in their accumulation in snowpack.

280 The concentrations of Mg$^{2+}$ were positively and significantly correlated with both Ca$^{2+}$ and nss-Ca$^{2+}$ ($\rho_{conc}$ = 0.70 and 0.47, respectively; the latter coefficient was higher for loads at 0.56; Table 4), suggesting they share some non-marine source(s). Furthermore, all glaciers had greater Ca$^{2+}$:Mg$^{2+}$ ratios than seawater (0.32; (Millero et al., 2008) (Figure 3). It is likely that the excess Ca$^{2+}$ and Mg$^{2+}$ came from mineral particles, i.e. CaCO$_3$ (calcite), and local rock (or soil) dust (Kekonen et al., 2005) derived from calcareous rocks, especially limestone, dolostone and marble, which are abundant in (Dallmann, 1999) The presence of carbonate ions in the collected snow samples would explain the missing negative charge in the ionic balance (anion X⁻; Figure S3).

285 Sulphate (SO$_4^{2-}$) was highly and significantly ($p$-value <0.05) correlated with both Na$^+$ ($\rho_{load}$ = 0.92; $\rho_{conc}$ = 0.80) and Cl$^-$ ($\rho_{load}$=0.93; $\rho_{conc}$ = 0.75), indicating that sea spray is its main source. However Na$^+/SO_4^{2-}$ and Cl$^-:SO_4^{2-}$ ratios were well below seawater values (Millero et al., 2008) on most glaciers except those near Hornsund (WB and HB), suggesting inputs of nss-SO$_4^{2-}$ (Figure 3). Biogenic nss-SO$_4^{2-}$ can be deposited in the snow as an oxidized by-product of dimethyl sulphide (DMS) emitted by marine algal blooms (Gondwe et al., 2003), typically initiated in April but sometimes later (Ardyna et al., 2013). Another plausible source of nss-SO$_4^{2-}$ deposition in Svalbard is long-range transport of SO$_4^{2-}$ aerosols from biomass burning in the spring, or from fossil fuel combustion throughout the winter (Barrie, 1986; Law and Stohl, 2007; Nawrot et al., 2016). The nss-SO$_4^{2-}$ did not correlate significantly with other ionic species, suggesting a separate origin. An extra consideration is that in the southern region of the archipelago, the higher sea spray input could partially mask the nss-SO$_4^{2-}$ signal, which is a derived variable, because the larger uncertainty for greater Na$^+$ concentrations would disproportionately affect estimations of nss-SO$_4^{2-}$ at these sites.

300 Bulk ionic loads of SO$_4^{2-}$ in the snow pits were significantly and positively correlated with those of NO$_3^-$ ($\rho_{load}$= 0.55) and NH$_4^+$ ($\rho_{load}$= 0.68), but the correlations between weighted mean ionic concentrations were not significant, hinting at co-deposition (wet) rather than shared sources (Table 4). These species are known to form secondary aerosols (Karl et al., 2019; Schaap et al., 2004) and thus their proportions in aerosols may differ significantly from those in their source emissions. It is also possible that nitrogen species underwent further post-depositional photochemical reduction and evasion, thereby reducing their concentrations in snow (Curtis et al., 2018). Finally, we remark here that the snow pit sampling was done in April, earlier than the beginning of the oceanic algal bloom in the surrounding Svalbard basin, which could have led to underrepresentation of biological emissions from late spring in our samples.

313
<figure><img src="image_15.png" /></figure>

314 Spatial variations of ammonium loads ($NH_4^+$) across Svalbard glaciers mirrored the pattern shown by sea salt ions, with higher loads in the Hornsund region and lower loads in other areas. This was also reflected by significant correlations between bulk loads of $NH_4^+$ with those of $Na^+$ and $Cl^-$ ($\rho_{load}$ = 0.64 and 0.73, respectively), and with $Na^+$, $K^+$ and $Mg^{2+}$ by concentration ($\rho_{conc}$ = 0.47, 0.62 and 0.47, respectively), the latter relationships suggesting that some ammonium is deposited as coatings on crustal aerosols (Eastwood et al., 2009). Ammonium has been linked to biogenic, forest fire, and anthropogenic agricultural emissions (Trachsel et al., 2019). The higher annual snowpack load of $NH_4^+$, determined in the Hornsund region is more likely connected with biological sources than anthropogenic activities, although some contribution from biomass burning events cannot be excluded. The marine primary productivity in spring 2016 (April and May) was higher in the south-eastern ocean sector of the Svalbard archipelago (Figure S4), which could partially explain the higher $NH_4^+$ load. This would also explain the correlation between ammonium and sea-salt ions (Table 4). Locally, especially for HB, there may be extra $NH_4^+$ emissions from bird colonies (Keslinka et al., 2019; Wojczulanis K. et al., 2008).

327 Unlike $NH_4^+$, the bulk loading of $NO_3^-$ in snow was highest in northwestern Spitsbergen (Ny-Ålesund area), when compared to other parts of Svalbard. Deposition of $NO_3^-$ in Arctic snow is often associated with the long-range atmospheric transport of $NO_x$ and related N species from anthropogenic source regions at lower latitudes (Björkman et al., 2014; Fibiger et al., 2016; Vega et al., 2015a). Differences in $NO_3^-$ loads in snow in various parts of Svalbard might therefore reflect differences in the transport pathways of precipitating air masses, including formation of secondary aerosols, or post-depositional processes, rather than local emissions. While local shipping routes and the settlement of Ny Ålesund itself may contribute $NO_3^-$ emissions (Winther et al., 2014), the highest share of the total ionic load of $NO_3^-$ was found in the accumulation zone of HDF (9% of the total ionic load; Figure S1). Given that HDF is the most remote site from Ny Ålesund relative to KVG or ALB, it should not capture a high share of local pollution. The highest correlation coefficient for $NO_3^-$, both in terms of concentrations and loads, was found with nss-Ca$^{2+}$. This would support both the formation of calcium nitrate in the atmosphere (Gibson et al., 2006) or post-depositional processes removing the $NO_3^-$ from layers poor in Ca$^{2+}$, since calcium has been hypothesised to stabilise the nitrate in snowpack against post-depositional losses (Kekonen et al., 2017).

### 4.2. Chlorine depletion

344 Although $Na^+$ and $Cl^-$, the main species of sea salt, were significantly correlated ($\rho_{conc}$ = 0.95), the values of the $Cl^/-Na^+$ ratio in snow were lower than that in seawater on most studied glaciers, except those near Hornsund (Figure 3), suggesting a $Cl^-$ deficit at the more northerly sites. A possible explanation of this $Cl^-$ deficit might be de-chlorination of the sea spray aerosol during transport or, less likely, at the snow-atmosphere interface. This reaction occurs between sea salt particles, containing NaCl, and $NO_3^-$, $SO_4^{2-}$, or organic acids to release gaseous HCl (Zhuang et al., 1999). We calculated the percentage of $Cl^-$
<figure><img src="image_16.png" /></figure>

As described earlier, the SWE-weighted mean δ¹⁸O and δ²H values in glacier snow pits decreased significantly with increasing latitude across Svalbard, the least negative values occurring on glaciers of the Hornsund region, and the most negative in Austfonna (Table 2). This pattern follows the climate gradient across the archipelago, milder in the south, colder in the north. Part of the south-north contrast in δ values could be explained by the lower mean altitude of glacier sites in the Hornsund region compared to some of the higher-elevation sites further north on Spitsbergen or on Austfonna, and the relationship with elevation was similar for both isotopic ratios in the collected dataset.

The deuterium excess ($d = \delta^{2}H - (8\cdot\delta^{18}O)$) is mainly influenced by the source region of the precipitating moisture and in particular by the sea surface temperature. In addition, $d$ is also influenced by the temperature gradient between the moisture source and precipitation area. The SWE-weighted mean $d$ values in Svalbard snow pits varied within a relatively narrow range of 6.74‰ (from 10.10 to 16.84 ‰), and similarly to δ¹⁸O, showed no clear gradient with elevation or longitude. Deuterium excess showed a significant correlation with latitude, at $\rho = 0.60$ ($p < 0.01$). A more detailed analysis of $d$ by latitude showed that only beyond 79.2 °N, i.e. in Austfonna snow pits, was $d$ significantly different than at other sites (Kruskal-Wallis test, $z = 4.23$, $p < 0.04$). This is consistent with lower temperatures and evaporation rates in the more northern waters around Svalbard, and suggests that snowfall on AF is at least partly affected by a different, more northerly moisture source than the rest of the archipelago.

404

### 4.5 Effect of elevation: a case study of Na

The glacier survey carried out during the C2S3 project afforded the opportunity to investigate the possible effect of elevation on the ionic composition of the snowpack. To do this, we compared the bulk load and SWE-weighted mean concentration of Na⁺ across all studied snow pits, ordered by elevation (Figure 4). Overall, both Na⁺ loads and concentrations decreased with increasing altitude ($\rho_{load} = -0.24$, $p > 0.05$; $\rho_{conc} = -0.72$, $p < 0.05$). This likely reflects greater local sea spray aerosol deposition at lower, compared to higher, glacier sites. We then computed linear (Pearson) correlation coefficients ($R$, with associated $p$-values) between log-transformed Na⁺ loadings (log(Na$_{load}$)) and δ¹⁸O for all snow pits in the accumulation zones of glaciers (Figure 5). The calculation was performed with all snow layers. The Na⁺ load was used as sea-spray tracer, while the δ¹⁸O was assumed to vary with moisture source between discrete snowfall events. We found that the positive correlation between log(Na$_{load}$) and δ¹⁸O increased with elevation from $R = 0.1$ (HB3; 396 m a.s.l.) to $R = 0.65$ (LF3; 1193 m a.s.l.), and reached a 95 % threshold of significance ($R > 0.3$) for glaciers sites above 600 m a.s.l. (KVG, AF, LF and HDF; Figure 5). The average distance was a comparatively negligible factor in explaining the correlation between log(Na$_{load}$) and δ¹⁸O.

420

The increase in strength and significance of the log(Na$_{load}$)-δ¹⁸O correlation with altitude might be explained by different contributions of locally-emitted ssNa⁺, relative to those of Na⁺ from more distant sources. Sites located at lower altitudes are proportionally more affected by local sea spray deposition,
<figure><img src="image_17.png" /></figure>

with or without snowfall. Conversely, sites at higher elevations likely receive a larger share of their ionic load from more distant sources, and by wet deposition through snowfall. At the four sites (KVG, AF, LF and HDF) where the log(Na<sub>load</sub>)-δ<sup>18</sup>O correlation was significant, increases in δ<sup>18</sup>O in snow layers were often associated with higher Na<sup>+</sup> concentrations. The isotopically heavier (less negative) δ<sup>18</sup>O values suggests that the co-registered Na<sup>+</sup> enhancements were associated with precipitation of relatively warm air, probably advected from lower latitudes. Air masses arriving from the south travel across the ocean for an extended time, which can enrich them in sea spray aerosol and hence in Na<sup>+</sup>. It is also possible that the poorer log(Na<sub>load</sub>)-δ<sup>18</sup>O correlation at lower altitude glacier sites is partly due to stronger post-depositional modification of isotopic and ionic signals in snowpack related to more frequent melt-refreeze episodes.

434

435 **5.Summary and Conclusion**

436 We have quantified and described, for the first time, the spatial distribution of major ion loads (Ca<sup>2+</sup>, K<sup>+</sup>, Na<sup>2+</sup>, Mg<sup>2+</sup>, NH<sub>4</sub><sup>+</sup>, SO<sub>4</sub><sup>2-</sup>, Br<sup>-</sup>, Cl<sup>-</sup> and NO<sub>3</sub><sup>-</sup>) and variations of δ<sup>18</sup>O and δ<sup>2</sup>H in the snowpack on glaciers across Svalbard for a single accumulation season (2015-2016). The highest total ionic loads were found in the southern region of Spitsbergen (Hornsund area), and exceeded 8 g m<sup>-2</sup>. Conversely, the lowest total ionic loads (≤ 0.6 g m<sup>-2</sup>) were found at sites in central or northwestern Spitsbergen (LF and HDF). Sea salt ions (Cl<sup>-</sup>, Na<sup>+</sup> and SO<sub>4</sub><sup>2-</sup>) dominated the ionic loads at all sites, but their share was highest at sites near Hornsund, for e.g., 48% Cl<sup>-</sup>, compared to only 29% on Holtedahlfonna. Relatively elevated Ca<sup>2+</sup>/Mg<sup>2+</sup> ratios in snow at all sites indicated non-sea-salt Ca<sup>2+</sup> inputs, most likely in the form of carbonate dust. Unlike other ions, NO<sub>3</sub><sup>-</sup> had the highest loads in glaciers of northwestern Spitsbergen, and the lowest at LF. The nitrogen species, NO<sub>3</sub><sup>-</sup> and NH<sub>4</sub><sup>+</sup>, showed distinct spatial distribution patterns. The highest NO<sub>3</sub><sup>-</sup> loads were found in the northwestern part of Svalbard, while the highest NH<sub>4</sub><sup>+</sup> loads were in the southwest. Bromide (Br<sup>-</sup>) was most enriched in snow relative to seawater at AF and LF, the glacier sites located closest to areas with first-year sea ice cover. This supports first-year sea ice being an important source of non-sea salt Br<sup>-</sup> in the polar atmosphere.

450

451 An increasing, positive correlation between log(Na<sub>load</sub>) and δ<sup>18</sup>O as a function of elevation sites suggests that locations above 600-700 m a.s.l. are influenced by a proportionally higher share of ions from distant sources, while the lower sites are exposed to more local sources, especially sea spray. These findings confirm that the optimal sites to study the effects of long-range pollution deposition in Svalbard are those found at higher elevations sites, such as the accumulation zones of HDF or LF, because they are the least impacted by the local aerosol emissions. The current study gives the first picture of the ionic composition in the Svalbard snowpack in different regions across the archipelago, in the context of which processes are relevant in controlling the annual snowpack chemical composition there, especially the influence of local and long-range transport.

460
<figure><img src="image_18.png" /></figure>

461 Acknowledgements

462 The work developed here was supported through grants 246731/E10 and 257636/E10 from the Svalbard

463 Science Forum /(Research Council of Norway), by the Gothenburg Centre of Advanced Studies, BECC -

464 Biodiversity and Ecosystem Services in a Changing Climate, Gothenburg Air and Climate Centre,

465 International Arctic Science Committee - Cryosphere working group and the Norwegian Polar Institute.

466 Part of fieldwork has been conducted thanks to the funds of the Leading National Research Centre

467 (KNOW) in Poland, received by the Centre for Polar Studies for the period 2014–2018. This research

468 was also partially supported within statutory activities No 3841/E-41/S/2020 of the Ministry of Science

469 and Higher Education of Poland. The project has received further funding from the European Union's

470 Horizon 2020 research and innovation programme under grant agreement no. 689443 via project iCUPE

471 (Integrative and Comprehensive Understanding on Polar Environments).

472
<figure><img src="image_19.png" /></figure>

473 REFERENCES

474

475 Aas, K. S., Dunse, T., Collier, E., Schuler, T. V., Berntsen, T. K., Kohler, J., and Luks, B.: The climatic mass balance of Svalbard glaciers: a 10-year simulation with a coupled atmosphere–glacier mass balance model, The Cryosphere, 10, 1089–1104, 2016.

478 Ardyna, M., Babin, M., Gosselin, M., Devred, E., Bélanger, S., Matsuoka, A., and Tremblay, J.-E.: Parameterization of vertical chlorophyll a in the Arctic Ocean: impact of the subsurface chlorophyll maximum on regional, seasonal, and annual primary production estimates, Biogeosciences, 10, 4383–4404, 2013.

482 Barbante, C., Spolaor, A., Cairns, W. R. L., and Boutron, C.: Man's footprint on the Arctic environment as revealed by analysis of ice and snow, Earth-Sci Rev, 168, 218-231, 2017.

484 Barbaro, E., Spolaor, A., Karroca, O., Park, K.-T., Martma, T., Isaksson, E., Kohler, J., Gallet, J. C., Bjorkman, M. P., Cappelletti, D., Sreen, G., Zangrando, R., Barbante, C., and Gambaro, A.: Free amino acids in the Arctic snow and ice core samples: Potential markers for paleoclimatic studies, Sci Total Environ, 607-608, 454-462, 2017.

488 Barrie, L. A.: Arctic air pollution: An overview of current knowledge, Atmospheric Environment (1967), 20, 643-663, 1986.

490 Björkman, M. P., Vega, C. P., Kühnel, R., Spataro, F., Ianniello, A., Esposito, G., Kaiser, J., Marca, A., Hodson, A., Isaksson, E., and Roberts, T. J.: Nitrate postdeposition processes in Svalbard surface snow, Journal of Geophysical Research: Atmospheres, 119, 12,953-12,976, 2014.

493 Brage, B. H., Ketil Isaksen, Rasmus E. Benestad, Jack Kohler, Åshild Ø Pedersen, Leif E Loe, Stephen J. Coulson, Jan Otto Larsen, and Varpe, Ø.: Warmer and wetter winters: characteristics and implications of an extreme weather event in the High Arctic, Environ. Res. Lett., 9, 2014.

496 Brimblecombe, P., Clegg, S. L., Davies, T. D., Shooter, D., and Tranter, M.: Observations of the preferential loss of major ions from melting snow and laboratory ice, Water Research, 21, 1279-1286, 1987.

499 Cogley, J. G., R. Hock, L.A. Rasmussen, A.A. Arendt, A. Bauder, R.J. Braithwaite, P. Jansson, G. Kaser, M. Möller, Nicholson, L., and Zemp., M.: Glossary of Glacier Mass Balance and Related Terms, IHP-VII Technical Documents in Hydrology, IACS Contribution No. 2, Unesco-IHP, Paris, 86, 2011.

503 Curtis, C. J., Kaiser, J., Marca, A., Anderson, N. J., Simpson, G., Jones, V., and Whiteford, E.: Spatial variations in snowpack chemistry, isotopic composition of NO3– and nitrogen deposition from the ice sheet margin to the coast of western Greenland, Biogeosciences, 15, 529-550, 2018.

506 Dahlke, S., Hughes, N. E., Wagner, P. M., Gerland, S., Wawrzyniak, T., Ivanov, B., and Maturilli, M.: The observed recent surface air temperature development across Svalbard and concurring footprints in local sea ice cover, International Journal of Climatology, n/a, 2020.

509 Dallmann, W. K.: The geology of Svalbard, Norwegian Polar Institute, 1999.

510 Eastwood, M. L., Cremel, S., Wheeler, M., Murray, B. J., Girard, E., and Bertram, A. K.: Effects of sulfuric acid and ammonium sulfate coatings on the ice nucleation properties of kaolinite particles, Geophys Res Lett, 36, 2009.

513 Eneroth, K., Kjellström, E., and Holmén, K.: A trajectory climatology for Svalbard; investigating how atmospheric flow patterns influence observed tracer concentrations, Physics and Chemistry of the Earth, Parts A/B/C, 28, 1191-1203, 2003.

516 Fibiger, D. L., Dibb, J. E., Chen, D., Thomas, J. L., Burkhart, J. F., Huey, L. G., and Hastings, M. G.: Analysis of nitrate in the snow and atmosphere at Summit, Greenland: Chemistry and transport, Journal of Geophysical Research: Atmospheres, 121, 5010-5030, 2016.

519 Forland, E. J., Benestad, R., Hanssen-Bauer, I., Haugen, J. E., and Skaugen, T. E.: Temperature and Precipitation Development at Svalbard 1900&#8211;2100, Advances in Meteorology, 2011, 14, 2011.

522 Forsström, S., Ström, J., Pedersen, C. A., Isaksson, E., and Gerland, S.: Elemental carbon distribution in Svalbard snow, Journal of Geophysical Research: Atmospheres, 114, 2009.

524 Gallet, J. C., Bjorkman, M. P., Larose, C., Luks, B., Martma, T., and Zdanowicz, C.: Protocols and recommendations for the measurement of snow physical properties, and sampling of snow for black carbon, water isotopes, major ions and microorganisms, Norsk Polarinstitutt, 46, 2018.
<figure><img src="image_20.png" /></figure>

527 Gibson, E. R., Hudson, P. K., and Grassian, V. H.: Physicochemical Properties of Nitrate Aerosols: Implications for the Atmosphere, The Journal of Physical Chemistry A, 110, 11785-11799, 2006.

528 Gondwe, M., Krol, M., Gieskes, W., Klaassen, W., and de Baar, H.: The contribution of ocean-leaving DMS to the global atmospheric burdens of DMS, MSA, SO2, and NSS SO4=, Global Biogeochem Cy, 17, 2003.

529 Goto-Azuma, K., Nakawo, M., Jinkang, H., Watanabe, O., and Azuma, N.: Melt-induced relocation of ions in glaciers and in a seasonal snowpack, Snow Ice Cover. Interact with Atmos. Ecosyst., 223, 287-297, 1994.

530 Hodgkins, R. and Tranter, M.: Solute in high arctic glacier snow cover and its impact on runoff chemistry, Annals of Glaciology, 26, 156-160, 2017.

531 Isaksen, K., Nordli, Ø., Førland, E. J., Łupikasza, E., Eastwood, S., and Niedźwiedź, T.: Recent warming on Spitsbergen—Influence of atmospheric circulation and sea ice cover, Journal of Geophysical Research: Atmospheres, 121, 11,913-911,931, 2016.

532 Isaksson, E., Hermanson, M., Hicks, S., Igarashi, M., Kamiyama K., Moore, J., Motoyama, H., Muir, D., Pohjola, V., Vaikmae, R., Van de Wal, R. S. W., and Watanabe, O.: Ice cores from Svalbard—useful archives of past climate and pollution history, 28, 1217-1228, 2003.

533 Jacobi, H. W., Obleitner, F., Da Costa, S., Ginot, P., Eleftheriadis, K., Aas, W., and Zanatta, M.: Deposition of ionic species and black carbon to the Arctic snowpack: combining snow pit observations with modeling, Atmos. Chem. Phys., 19, 10361-10377, 2019.

534 Karl, M., Leck, C., Mashayekhy Rad, F., Bäcklund, A., Lopez-Aparicio, S., and Heintzenberg, J.: New insights in sources of the sub-micrometre aerosol at Mt. Zeppelin observatory (Spitsbergen) in the year 2015, Tellus B: Chemical and Physical Meteorology, 71, 1613143, 2019.

535 Kekonen, T., Moore, J., Perämäki, P., Mulvaney, R., Isaksson, E., Pohjola, V., and van de Wal, R. S. W.: The 800 year long ion record from the Lomonosovfonna (Svalbard) ice core, Journal of Geophysical Research: Atmospheres, 110, 2005.

536 Kekonen, T., Moore, J. C., Mulvaney, R., Isaksson, E., Pohjola, V., and van de Wal, R. S. W.: A 800 year record of nitrate from the Lomonosovfonna ice core, Svalbard, Annals of Glaciology, 35, 261-265, 2017.

537 Keslinka, L. K., Wojczulanis-Jakubas, K., Jakubas, D., and Neubauer, G.: Determinants of the little auk (Alle alle) breeding colony location and size in W and NW coast of Spitsbergen, PLOS ONE, 14, e0212668, 2019.

538 Kuhn, M.: The nutrient cycle through snow and ice, a review, Aquatic Sciences, 63, 150-167, 2001.

539 Kühnel, R., Roberts, T. J., Björkman, M. P., Isaksson, E., Aas, W., Holmén, K., and Ström, J.: 20-Year Climatology of NO3 and NH4+ Wet Deposition at Ny-Alesund, Svalbard, Advances in Meteorology, 2011, 10, 2011.

540 Law, K. S. and Stohl, A.: Arctic Air Pollution: Origins and Impacts, Science, 315, 1537, 2007.

541 Maturilli, M., Herber, A., and König-Langlo, G.: Climatology and time series of surface meteorology in Ny-Älesund, Svalbard, Earth Syst. Sci. Data, 5, 155-163, 2013.

542 Millero, F. J., Feistel, R., Wright, D. G., and McDougall, T. J.: The composition of Standard Seawater and the definition of the Reference-Composition Salinity Scale, Deep Sea Research Part I: Oceanographic Research Papers, 55, 50-72, 2008.

543 Möller, M. and Kohler, J.: Differing Climatic Mass Balance Evolution Across Svalbard Glacier Regions Over 1900-2010, Frontiers in Earth Science, 6, 128, 2018.

544 Nawrot, A. P., Migała, K., Luks, B., Pakszys, P., and Głowacki, P.: Chemistry of snow cover and acidic snowfall during a season with a high level of air pollution on the Hans Glacier, Spitsbergen, Polar Science, 10, 249-261, 2016.

545 Nordli, Ø., Przybylak, R., Ogilvie, A. E. J., and Isaksen, K.: Long-term temperature trends and variability on Spitsbergen: the extended Svalbard Airport temperature series, 1898-2012, Polar Res, 33, 21349, 2014.

546 Peterson, P. K., Hartwig, M., May, N. W., Schwartz, E., Rigor, I., Ermold, W., Steele, M., Morison, J. H., Nghiem, S. V., and Pratt, K. A.: Snowpack measurements suggest role for multi-year sea ice regions in Arctic atmospheric bromine and chlorine chemistry, Elem Sci Anth, 7(1), 14, 2019.

547 Pohjola, V. A., Moore, J. C., Isaksson, E., Jauhiainen, T., van de Wal, R. S. W., Martma, T., Meijer, H. A. J., and Vaikmäe, R.: Effect of periodic melting on geochemical and isotopic signals in an ice core
<figure><img src="image_21.png" /></figure>

<figure><img src="image_22.png" /></figure>

581 from Lomonosovfonna, Svalbard, Journal of Geophysical Research: Atmospheres, 107, ACL 1-1-582 ACL 1-14, 2002.

583 Rinke, A., Maturilli, M., Graham, R. M., Matthes, H., Handorf, D., Cohen, L., Hudson, S. R., and 584 Moore, J. C.: Extreme cyclone events in the Arctic: Wintertime variability and trends, Environ Res 585 Lett, 12, 094006, 2017.

586 Schaap, M., van Loon, M., ten Brink, H. M., Dentener, F. J., and Builtjes, P. J. H.: Secondary inorganic 587 aerosol simulations for Europe with special attention to nitrate, Atmos. Chem. Phys., 4, 857-874, 588 2004.

589 Schüpbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., 590 Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, 591 H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P., Winstrup, M., Wegner, A., 592 Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., 593 Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., 594 Barbante, C., Kang, J. H., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., 595 Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O., McConnell, J., and Wolff, E. W.: Greenland 596 records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene, Nature 597 Communications, 9, 1476, 2018.

598 Semb, A., Brækkan, R., and Joranger, E.: Major ions in Spitsbergen snow samples, Geophys Res Lett, 599 11, 445-448, 1984.

600 Spolaor, A., Barbaro, E., Cappelletti, D., Turetta, C., Mazzola, M., Giardi, F., Björkman, M. P., 601 Lucchetta, F., Dallo, F., Pfaffhuber, K. A., Angot, H., Dommergue, A., Maturilli, M., Saiz-Lopez, A., 602 Barbante, C., and Cairns, W. R. L.: Diurnal cycle of iodine, bromine, and mercury concentrations in 603 Svalbard surface snow, Atmos. Chem. Phys., 19, 13325-13339, 2019.

604 Spolaor, A., Barbaro, E., Christille, J. M., Kirchgeorg, T., Giardi, F., Cappelletti, D., Turetta, C., 605 Bernagozzi, A., Björkman, M. P., Bertolini, E., and Barbante, C.: Evolution of the Svalbard annual 606 snow layer during the melting phase, Rendiconti Lincei, doi: 10.1007/s12210-015-0500-8, 2016. 1-8, 607 2016.

608 Spolaor, A., Gabrieli, J., Martma, T., Kohler, J., Björkman, M. B., Isaksson, E., Varin, C., Vallelonga, 609 P., Plane, J. M. C., and Barbante, C.: Sea ice dynamics influence halogen deposition to Svalbard, The 610 Cryosphere, 7, 1645-1658, 2013.

611 Spolaor, A., Vallelonga, P., Gabrieli, J., Martma, T., Björkman, M. P., Isaksson, E., Cozzi, G., Turetta, 612 C., Kjær, H. A., Curran, M. A. J., Moy, A. D., Schönhardt, A., Blechschmidt, A. M., Burrows, J. P., 613 Plane, J. M. C., and Barbante, C.: Seasonality of halogen deposition in polar snow and ice, Atmos. 614 Chem. Phys., 14, 9613-9622, 2014.

615 Thompson, L. G., Mosley-Thompson, E., Davis, M. E., Henderson, K. A., Brecher, H. H., Zagorodnov, 616 V. S., Mashiotta, T. A., Lin, P.-N., Mikhalenko, V. N., Hardy, D. R., and Beer, J. r.: Kilimanjaro Ice 617 Core Records: Evidence of Holocene Climate Change in Tropical Africa, Science, 298, 589-593, 618 2002.

619 Trachsel, J. C., Avak, S. E., Edebeli, J., Schneebeli, M., Bartels-Rausch, T., Bruetsch, S., and Eichler, 620 A.: Microscale Rearrangement of Ammonium Induced by Snow Metamorphism, Frontiers in Earth 621 Science, 7, 194, 2019.

622 van Pelt, W., Pohjola, V., Pettersson, R., Marchenko, S., Kohler, J., Luks, B., Hagen, J. O., Schuler, T. 623 V., Dunse, T., Noël, B., and Reijmer, C.: A long-term dataset of climatic mass balance, snow 624 conditions, and runoff in Svalbard (1957–2018), The Cryosphere, 13, 2259-2280, 2019.

625 Vecchiato, M., Barbaro, E., Spolaor, A., Burgay, F., Barbante, C., Piazza, R., and Gambaro, A.: 626 Fragrances and PAHs in snow and seawater of Ny-Ålesund (Svalbard): Local and long-range 627 contamination, Environmental Pollution, 242, 1740-1747, 2018.

628 Vega, C. P., Björkman, M. P., Pohjola, V. A., Isaksson, E., Pettersson, R., Martma, T., Marca, A., and 629 Kaiser, J.: Nitrate stable isotopes in snow and ice samples from four Svalbard sites, Polar Res, 34, 630 2015a.

631 Vega, C. P., Pohjola, V. A., Beaudon, E., Claremar, B., van Pelt, W. J. J., Pettersson, R., Isaksson, E., 632 Martma, T., Schwikowski, M., and Bøggild, C. E.: A synthetic ice core approach to estimate ion 633 relocation in an ice field site experiencing periodical melt; a case study on Lomonosovfonna, 634 Svalbard, The Cryosphere Discuss., 9, 5053-5095, 2015b.
<figure><img src="image_23.png" /></figure>

<figure><img src="image_24.png" /></figure>

635 Virkkunen, K., Moore, J. C., Isaksson, E., Pohjola, V., Perämäki, P., Grinsted, A., and Kekonen, T.:

636 Warm summers and ion concentrations in snow: comparison of present day with Medieval Warm

637 Epoch from snow pits and an ice core from Lomonosovfonna, Svalbard, J Glaciol, 53, 623-634, 2007.

638 Winther, J.-G., Bruland, O., Sand, K., Gerland, S., Marechal, D., Ivanov, B., Gøowacki, P., and König,

639 M.: Snow research in Svalbard—an overview, Polar Res, 22, 125-144, 2003.

640 Winther, M., Christensen, J. H., Plejdrup, M. S., Ravn, E. S., Eriksson, Ö. F., and Kristensen, H. O.:

641 Emission inventories for ships in the arctic based on satellite sampled AIS data, Atmos Environ, 91,

642 1-14, 2014.

643 Wojczulanis K., Jakubas D., and Stempniewicz, L.: Avifauna of Hornsund area, SW Spitsbergen: present

644 state and recent changes, Polish Polar Research, 29, 187-197, 2008.

645 Wolff, E. W., Barbante, C., Becagli, S., Bigler, M., Boutron, C. F., Castellano, E., De Angelis, M.,

646 Federer, U., Fischer, H., and Fundel, F.: Changes in environment over the last 800,000 years from

647 chemical analysis of the EPICA Dome C ice core, Quaternary Sci Rev, 29, 285-295, 2010.

648 Zhuang, H., Chan, C. K., Fang, M., and Wexler, A. S.: Formation of nitrate and non-sea-salt sulfate on

649 coarse particles, Atmos Environ, 33, 4223-4233, 1999.

650

651
<figure><img src="image_25.png" /></figure>

<figure><img src="image_26.png" /></figure>

652 TABLES

653 **Table 1.** Table 1. laciers and sampling sites included in this study with their main characteristic. AWS: atmospheric weather station; UiO: University of Oslo; ThèMA: Thèoriser & Modèliser pour Amènager, University of Franche-Comté; NPI: Norwegian Polar Institute; IMAU: Institute for Marine and Atmospheric Research, Utrecht University; UoS: University of Silesia, IG PAS – Institute of Geophysics, Polish Academy of Sciences; CNR – Consiglio Nazionale delle Ricerche. The seven glaciers were considered at three different altitudes: 1) lower ablation zone; 2) ELA; 3) upper accumulation zone. Exceptionally, two snow pits (KVG 1 and KVG 1.5) were dug in the ablation zone of Kongsvegen glacier.

660

661 **Table 2.** Total load (mg m⁻²) of major ions, calculated as the sum of loads in all layers of each snow pit. Sea salt sulphate (ss-SO₄²⁻) and non-sea-salt sulphate (nss-SO₄²⁻) are expressed as mg m⁻², while chloride depletion (Cl⁻_dep) is given as a percentage and bromide enrichment (Brₐₗ) refers to an enrichment compare to sea water. Average SWE-weighted stable water isotope ratios (δ¹⁸O and δ²H) and average deuterium excess (d) are also reported.

666

667 **Table 3.** Chemical loads (mg m⁻²) of selected elements from the 2016 sampling and earlier studies at Lomonosovfonna summit (LF3), corresponding to the concentrations given in Fig. 4.

669

670 **Table 4.** Spearman rank order correlations for all 7 glaciers (n=22 locations) with a p < 0.05: a) of total loads (mg m⁻²) of major ions (calculated as the sum of loads in all layers of each snow pit), b) of volume-weighted average concentrations of each snow pit, calculated by dividing the total load of each snow pit by its total water equivalent. Non-sea-salt (nss) components were calculated based on the seawater ratios to Na⁺ (0.038 and 0.252, respectively, for Ca²⁺ and SO₄²⁻ in mg L⁻¹; Millero et al. 2008); ns = not significant with p-value > 0.05.
<figure><img src="image_27.png" /></figure>

676 FIGURES

677

678 **Figure 1.** Total snowpack loads (mg m⁻²) of major ions in 22 snow pits collected on glaciers during the C2S3 project. Seven glaciers were sampled in three snow pits in the lower ablation zone (1), near the equilibrium line (2) and in the upper accumulation zone (3), except on Kongsvegen glacier (KVG) where there was an extra snow pit sampled within the ablation zone. Glacier site abbreviations are given in Table 1.

679

680

681

<figure><img src="image_28.png" /></figure>

682

683

684

685

686

687
<figure><img src="image_29.png" /><figcaption>**Figure 2.** Calculated ionic loads in the snowpack (mg m⁻²) at the 7 glacier sites sampled during the C2S3 project. Snow pits for each glacier are marked with the same colour and ordered from lower (left) to higher altitudes (right). For the KGV another snow pit was dug between glaciers zone 1 and 2.</figcaption></figure>

691

<figure><img src="image_30.png" /></figure>

692

693

694

695

696

697

698

699

700

701

702
<figure><img src="image_31.png" /></figure>

Figure 3. Panels from top: 1) Cl-/Na⁺; 2) Na⁺/SO₄²⁻; 3) Cl-/SO₄²⁻; 4) the total loads of sea-salt sulphate (ss-SO₄²⁻) and non-sea-salt sulphate (nss-SO₄²⁻), and 5) Ca²⁺/Mg²⁺ - for all glaciers investigated during the C2S3 project (in the spring 2016).

706

707

<figure><img src="image_32.png" /></figure>

708
<figure><img src="image_33.png" /></figure>

709

710 **Figure 4.** Sodium load in snow pits ordered by increasing elevation in m a.s.l., indicated by the red lines.

711 The colours identify areas where the snow pits have been excavated: each colour represents a separate glacier

712 (HB - blue; WB - purple; ALB - red; LF - green; KVG - pink; AF - light blue; HDF - orange). IQR =

713 inter-quartile range, i.e. the difference between the value of quartiles 3 and 1.

714

<figure><img src="image_34.png" /></figure>

715

716

717

718

719

720

721

722

723

724
<figure><img src="image_35.png" /></figure>

Figure 5. The correlation coefficient between oxygen isotope ratio (δ¹⁸O) and log[Naload] increases with elevation. The left axis represents the correlation coefficient (R) between log[Naload] and δ¹⁸O, using the entire dataset for each snow pit (i.e. all layers have been used for the statistical correlation). The x axis indicates the altitude of the snow pit. The upper panel shows the p-value: correlations have been considered statistically significant if p < 0.05.

<figure><img src="image_36.png" /></figure>
<figure><img src="image_37.png" /></figure>

<figure><img src="image_38.png" /><figcaption>**Table 1.** Glaciers and sampling sites included in this study with their main characteristics. AWS: automatic weather station; UIO: University of Oslo; ThéMA: Théoriser & Modéliser pour Aménager, Université de Franche-Comté; NPI: Norwegian Polar Institute; IMAU: Institute for Marine and Atmospheric Research, Utrecht University; UoS: University of Silesia, IG PAS – Institute of Geophysics, Polish Academy of Sciences; CNR – Consiglio Nazionale delle Ricerche.</figcaption></figure>

<table><thead><tr><th rowspan="2">Glacier</th><th rowspan="2">Site</th><th rowspan="2">Zone</th><th rowspan="2"></th><th colspan="5">AWS</th><th colspan="3">Air Temp.</th><th colspan="2">Snow Water Equivalen</th></tr><tr><th>Lat. (°N)</th><th>Lon. (°E)</th><th>Elev. (m)</th><th>Date (dd.mm.yyyy)</th><th>Temp. (°C)</th><th>height (cm)</th><th>t (mm)</th><th>(SWE)</th></tr></thead><tbody><tr><td rowspan="3">Austfonna</td><td>AF1</td><td>ablation</td><td rowspan="3">UIO</td><td>79.734</td><td>22.414</td><td>336</td><td>21.04.2016</td><td>-13.5</td><td>106</td><td>330.50</td><td></td></tr><tr><td>AF2</td><td>equilibrium line</td><td>79.767</td><td>22.825</td><td>507</td><td>23.04.2016</td><td>-7.1</td><td>135</td><td>439.59</td><td></td></tr><tr><td>AF3</td><td>accumulation</td><td>79.832</td><td>24.004</td><td>785</td><td>24.04.2016</td><td>-14.7</td><td>181</td><td>803.93</td><td></td></tr><tr><td rowspan="3">Austre Lovénbreen</td><td>ALB1</td><td>ablation</td><td rowspan="3">ThéMA</td><td>78.883</td><td>12.136</td><td>195</td><td>25.04.2016</td><td>-3.7</td><td>81</td><td>296.66</td><td></td></tr><tr><td>ALB2</td><td>equilibrium line</td><td>78.889</td><td>12.159</td><td>340</td><td>25.04.2016</td><td>-2.8</td><td>90</td><td>353.17</td><td></td></tr><tr><td>ALB3</td><td>accumulation</td><td>78.861</td><td>12.187</td><td>513</td><td>20.04.2016</td><td>-11.3</td><td>161</td><td>499.67</td><td></td></tr><tr><td rowspan="4">Kongsvegen</td><td>KVG1</td><td>ablation</td><td rowspan="4">NPI\CNR</td><td>78.830</td><td>12.759</td><td>226</td><td>13.04.2016</td><td>-13.9</td><td>20</td><td>51.29</td><td></td></tr><tr><td>KVG1.5</td><td>ablation</td><td>78.813</td><td>12.869</td><td>326</td><td>13.04.2016</td><td>-13.9</td><td>75</td><td>261.94</td><td></td></tr><tr><td>KVG 2</td><td>equilibrium line</td><td>78.780</td><td>13.153</td><td>534</td><td>11.04.2016</td><td>-17.5</td><td>162</td><td>575.78</td><td></td></tr><tr><td>KVG3</td><td>accumulation</td><td>78.756</td><td>13.336</td><td>672</td><td>12.04.2013</td><td>-15.5</td><td>234</td><td>880.13</td><td></td></tr><tr><td rowspan="3">Holtedahlfonna</td><td>HDF1</td><td>ablation</td><td rowspan="3">NPI\CNR</td><td>78.931</td><td>13.303</td><td>570</td><td>17.04.2016</td><td>-14.5</td><td>108</td><td>372.98</td><td></td></tr><tr><td>HDF2</td><td>equilibrium line</td><td>79.029</td><td>13.531</td><td>718</td><td>17.04.2016</td><td>-14.2</td><td>175</td><td>625.00</td><td></td></tr><tr><td>HDF3</td><td>accumulation</td><td>79.140</td><td>13.394</td><td>1119</td><td>15.04.2016</td><td>-18.1</td><td>201</td><td>732.08</td><td></td></tr><tr><td rowspan="3">Lomonosovfonna</td><td>LF1</td><td>ablation</td><td rowspan="3">IMAU</td><td>78.633</td><td>17.077</td><td>223</td><td>10.04.2016</td><td>-10.9</td><td>27</td><td>99.4</td><td></td></tr><tr><td>LF2</td><td>equilibrium line</td><td>78.691</td><td>17.150</td><td>523</td><td>9.04.2016</td><td>-5.8</td><td>94</td><td>277.28</td><td></td></tr><tr><td>LF3</td><td>accumulation</td><td>78.824</td><td>17.435</td><td>1193</td><td>11.04.2016</td><td>-24</td><td>146</td><td>487.01</td><td></td></tr><tr><td rowspan="3">Hansbreen</td><td>HB1</td><td>ablation</td><td rowspan="3">UoS/IG PAS</td><td>77.049</td><td>15.639</td><td>102</td><td>25.04.2016</td><td>-7.3</td><td>102</td><td>396.10</td><td></td></tr><tr><td>HB2</td><td>equilibrium line</td><td>77.083</td><td>15.639</td><td>275</td><td>25.04.2016</td><td>-6.9</td><td>169</td><td>640.28</td><td></td></tr><tr><td>HB3</td><td>accumulation</td><td>77.120</td><td>15.487</td><td>396</td><td>29.04.2016</td><td>0.7</td><td>288</td><td>1305.09</td><td></td></tr><tr><td rowspan="3">Werenskiöldbreen</td><td>WB1</td><td>ablation</td><td rowspan="3">UoS</td><td>77.075</td><td>15.313</td><td>166</td><td>16.04.2016</td><td>-9.2</td><td>81</td><td>328.34</td><td></td></tr><tr><td>WB2</td><td>equilibrium line</td><td>77.072</td><td>15.441</td><td>413</td><td>16.04.2016</td><td>-11.2</td><td>110</td><td>454.75</td><td></td></tr><tr><td>WB3</td><td>accumulation</td><td>77.092</td><td>15.489</td><td>528</td><td>18.04.2016</td><td>-11.1</td><td>330</td><td>1396.60</td><td></td></tr></tbody></table>
<figure><img src="image_39.png" /></figure>

<figure><img src="image_40.png" /><figcaption>**Table 2.** Total load (mg m⁻²) of major ions, calculated as the sum of loads in all layers of each snow pit. Sea salt sulphate (ss-SO₄²⁻) and non-sea-salt sulphate (nss-SO₄²⁻) are expressed as mg m⁻², while chloride depletion (Cl⁻_dep) is given as a percentage and bromide enrichment (Brₐₘₐ₅) refers to an enrichment compare to sea water. Average SWE-weighted stable water isotope ratios (δ¹⁸O and δ²H) and average deuterium excess (d) are also reported.</figcaption></figure>

<table><thead><tr><th>Cl⁻</th><th>Br⁻</th><th>SO₄²⁻</th><th>NO₃⁻</th><th>Na⁺</th><th>NH₄⁺</th><th>K⁺</th><th>Mg²⁺</th><th>Ca²⁺</th><th>ss-SO₄²⁻</th><th>nss-SO₄²⁻</th><th>Cl⁻_dep</th><th>%</th><th>Brₐₘₐ₅</th><th>δ¹⁸O</th><th>δ²H</th><th>d</th></tr></thead><tbody><tr><td>KVG1</td><td>190</td><td>0.4</td><td>96</td><td>6</td><td>421</td><td>0.3</td><td>7</td><td>37</td><td>20</td><td>106</td><td>nd</td><td>75</td><td>0.2</td><td>-9.69</td><td>-66.17</td><td>11.37</td></tr><tr><td>KVG1.5</td><td>281</td><td>1.9</td><td>157</td><td>45</td><td>327</td><td>0.9</td><td>6</td><td>36</td><td>33</td><td>82</td><td>75</td><td>52</td><td>1.0</td><td>-11.32</td><td>-78.25</td><td>12.34</td></tr><tr><td>KVG2</td><td>652</td><td>1.2</td><td>342</td><td>118</td><td>605</td><td>1.9</td><td>9</td><td>51</td><td>63</td><td>152</td><td>190</td><td>40</td><td>0.3</td><td>-12.51</td><td>-88.62</td><td>11.48</td></tr><tr><td>KVG3</td><td>1039</td><td>1.2</td><td>509</td><td>148</td><td>967</td><td>2.9</td><td>12</td><td>86</td><td>94</td><td>244</td><td>266</td><td>40</td><td>0.2</td><td>-12.72</td><td>-89.50</td><td>12.25</td></tr><tr><td>HDF1</td><td>373</td><td>1.3</td><td>144</td><td>74</td><td>267</td><td>2.6</td><td>4</td><td>23</td><td>33</td><td>68</td><td>79</td><td>21</td><td>0.9</td><td>-13.51</td><td>-94.37</td><td>13.75</td></tr><tr><td>HDF2</td><td>423</td><td>2.5</td><td>192</td><td>148</td><td>240</td><td>4.5</td><td>6</td><td>18</td><td>67</td><td>61</td><td>131</td><td>2</td><td>1.7</td><td>-13.91</td><td>-99.15</td><td>12.10</td></tr><tr><td>HDF3</td><td>227</td><td>0.8</td><td>65</td><td>51</td><td>170</td><td>4.5</td><td>9</td><td>12</td><td>45</td><td>43</td><td>22</td><td>25</td><td>0.8</td><td>-15.18</td><td>-104.51</td><td>16.97</td></tr><tr><td>ALB1</td><td>446</td><td>1.9</td><td>226</td><td>115</td><td>343</td><td>1.5</td><td>10</td><td>31</td><td>90</td><td>86</td><td>139</td><td>27</td><td>0.9</td><td>-11.22</td><td>-75.17</td><td>14.59</td></tr><tr><td>ALB2</td><td>294</td><td>1.4</td><td>158</td><td>87</td><td>221</td><td>1.6</td><td>4</td><td>17</td><td>38</td><td>56</td><td>107</td><td>25</td><td>1.2</td><td>-12.19</td><td>-83.11</td><td>14.40</td></tr><tr><td>ALB3</td><td>729</td><td>1.8</td><td>342</td><td>64</td><td>648</td><td>4.2</td><td>8</td><td>56</td><td>81</td><td>158</td><td>165</td><td>36</td><td>0.4</td><td>-12.40</td><td>-85.40</td><td>13.79</td></tr><tr><td>LF1</td><td>75</td><td>1.1</td><td>59</td><td>1</td><td>95</td><td>0.4</td><td>3</td><td>12</td><td>6</td><td>31</td><td>48</td><td>51</td><td>2.1</td><td>-11.61</td><td>-82.79</td><td>10.10</td></tr><tr><td>LF2</td><td>174</td><td>2.8</td><td>127</td><td>18</td><td>141</td><td>2.6</td><td>5</td><td>12</td><td>7</td><td>53</td><td>127</td><td>38</td><td>3.2</td><td>-14.54</td><td>-105.44</td><td>10.90</td></tr><tr><td>LF3</td><td>216</td><td>3.5</td><td>144</td><td>10</td><td>225</td><td>2.9</td><td>7</td><td>22</td><td>9</td><td>56</td><td>93</td><td>45</td><td>2.7</td><td>-15.14</td><td>-110.42</td><td>10.69</td></tr><tr><td>AF1</td><td>498</td><td>5.7</td><td>348</td><td>38</td><td>578</td><td>2.2</td><td>27</td><td>48</td><td>95</td><td>127</td><td>173</td><td>53</td><td>1.6</td><td>-14.34</td><td>-100.76</td><td>13.94</td></tr><tr><td>AF2</td><td>438</td><td>6.3</td><td>263</td><td>15</td><td>509</td><td>3.4</td><td>19</td><td>62</td><td>26</td><td>147</td><td>153</td><td>51</td><td>2.0</td><td>-16.00</td><td>-111.15</td><td>16.84</td></tr><tr><td>AF3</td><td>928</td><td>6.5</td><td>439</td><td>88</td><td>933</td><td>8.1</td><td>35</td><td>89</td><td>81</td><td>185</td><td>206</td><td>54</td><td>1.5</td><td>-13.89</td><td>-96.89</td><td>14.24</td></tr><tr><td>WB1</td><td>2041</td><td>4.7</td><td>332</td><td>34</td><td>1278</td><td>6.7</td><td>53</td><td>131</td><td>91</td><td>340</td><td>15</td><td>10</td><td>0.6</td><td>-10.17</td><td>-70.62</td><td>10.75</td></tr><tr><td>WB2</td><td>1584</td><td>2.7</td><td>304</td><td>38</td><td>1051</td><td>9.9</td><td>44</td><td>110</td><td>68</td><td>220</td><td>24</td><td>16</td><td>0.4</td><td>-10.25</td><td>-70.14</td><td>11.90</td></tr><tr><td>WB3</td><td>3922</td><td>7.2</td><td>713</td><td>118</td><td>2649</td><td>26.1</td><td>137</td><td>277</td><td>313</td><td>671</td><td>37</td><td>17</td><td>0.5</td><td>-9.54</td><td>-63.64</td><td>12.66</td></tr><tr><td>HB1</td><td>2680</td><td>6.2</td><td>482</td><td>46</td><td>1722</td><td>10.5</td><td>74</td><td>201</td><td>110</td><td>475</td><td>47</td><td>13</td><td>0.6</td><td>-11.14</td><td>-75.93</td><td>13.19</td></tr><tr><td>HB2</td><td>2499</td><td>2.8</td><td>490</td><td>185</td><td>1667</td><td>32.5</td><td>105</td><td>159</td><td>150</td><td>350</td><td>73</td><td>19</td><td>0.3</td><td>-10.69</td><td>-73.34</td><td>12.17</td></tr><tr><td>HB3</td><td>3964</td><td>6.5</td><td>719</td><td>118</td><td>2557</td><td>28.2</td><td>125</td><td>281</td><td>223</td><td>751</td><td>107</td><td>13</td><td>0.4</td><td>-11.25</td><td>-77.62</td><td>12.35</td></tr></tbody></table>
<figure><img src="image_41.png" /></figure>

<figure><img src="image_42.png" /><figcaption>**Table 3.** Loads (mg m⁻²) of selected major ions from the 2016 sampling and from earlier studies at Lomonosovfonna summit (LF3), corresponding to the concentrations given in Fig. 4.</figcaption></figure>

<table><thead><tr><th>Year</th><th>Na<sup>+</sup></th><th>Ca<sup>2+</sup></th><th>NO<sub>3</sub><sup>-</sup></th><th>ns<sup>ss-</sup><br>SO<sub>4</sub><sup>2+</sup></th><th>Study</th></tr></thead><tbody><tr><td>2002</td><td>126.7</td><td>7.1</td><td>27.3</td><td>37.1</td><td>(Virkkunen et al., 2007)</td></tr><tr><td>2009</td><td>n.a.</td><td>n.a.</td><td>33.5</td><td>n.a.</td><td>Vega C. (unpublished data)</td></tr><tr><td>2010</td><td>80.1</td><td>24.3</td><td>52.3</td><td>48.1</td><td>Vega C. (unpublished data)</td></tr><tr><td>2011</td><td>262.9</td><td>46.2</td><td>27.2</td><td>34.1</td><td>(Vega et al., 2015), Vega C. (unpublished data)</td></tr><tr><td>2016</td><td>222.2</td><td>7.2</td><td>11.4</td><td>93.0</td><td>This study</td></tr></tbody></table>
<figure><img src="image_43.png" /><figcaption>**Table 4.** Spearman rank order correlations of a) ionic loads (mg m⁻²) and b) SWE-weighted mean concentrations of major ions across all 7 glaciers (n=22 locations). ns = non-significant correlations (p-value > 0.05). Ionic loads were calculated from all snow pit layers, while SWE-weighted mean concentrations were calculated by dividing the ionic loads in each snow pit by its total SWE. Non-sea-salt (nss) components were estimated based from seawater ratios to Na⁺, 0.038 and 0.252, respectively, for Ca²⁺ and SO₄²⁻ in mg L⁻¹; Millero et al. 2008.</figcaption></figure>

a)

<table><thead><tr><th></th><th>Cl⁻</th><th>Br⁻</th><th>SO₄²⁻</th><th>NO₃⁻</th><th>Na⁺</th><th>NH₄⁺</th><th>K⁺</th><th>Mg²⁺</th><th>Ca²⁺</th><th>nss-SO₄²⁻</th></tr></thead><tbody><tr><td>Br⁻</td><td>0.53</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>SO₄²⁻</td><td>0.93</td><td>0.60</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>NO₃⁻</td><td>0.55</td><td>ns</td><td>0.55</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Na⁺</td><td>0.94</td><td>0.48</td><td>0.92</td><td>0.44</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>NH₄⁺</td><td>0.73</td><td>0.62</td><td>0.68</td><td>ns</td><td>0.64</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>K⁺</td><td>0.82</td><td>0.61</td><td>0.81</td><td>ns</td><td>0.85</td><td>0.75</td><td></td><td></td><td></td><td></td></tr><tr><td>Mg²⁺</td><td>0.90</td><td>0.51</td><td>0.88</td><td>ns</td><td>0.98</td><td>0.62</td><td>0.82</td><td></td><td></td><td></td></tr><tr><td>Ca²⁺</td><td>0.86</td><td>ns</td><td>0.83</td><td>0.69</td><td>0.82</td><td>0.61</td><td>0.76</td><td>0.71</td><td></td><td></td></tr><tr><td>nss-</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>SO₄²⁻</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td></tr><tr><td>nss-Ca²⁺</td><td>0.76</td><td>ns</td><td>0.75</td><td>0.77</td><td>0.68</td><td>0.56</td><td>0.66</td><td>0.56</td><td>0.96</td><td>ns</td></tr></tbody></table>

b)

<table><thead><tr><th></th><th>Cl⁻</th><th>Br⁻</th><th>SO₄²⁻</th><th>NO₃⁻</th><th>Na⁺</th><th>NH₄⁺</th><th>K⁺</th><th>Mg²⁺</th><th>Ca²⁺</th><th>nss-SO₄²⁻</th></tr></thead><tbody><tr><td>Br⁻</td><td>ns</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>SO₄²⁻</td><td>0.75</td><td>0.58</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>NO₃⁻</td><td>ns</td><td>-0.48</td><td>ns</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Na⁺</td><td>0.95</td><td>ns</td><td>0.80</td><td>ns</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>NH₄⁺</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>0.47</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>K⁺</td><td>0.83</td><td>0.46</td><td>0.73</td><td>ns</td><td>0.88</td><td>0.62</td><td></td><td></td><td></td><td></td></tr><tr><td>Mg²⁺</td><td>0.92</td><td>ns</td><td>0.78</td><td>ns</td><td>0.98</td><td>0.47</td><td>0.86</td><td></td><td></td><td></td></tr><tr><td>Ca²⁺</td><td>0.85</td><td>ns</td><td>0.64</td><td>0.44</td><td>0.76</td><td>ns</td><td>0.62</td><td>0.70</td><td></td><td></td></tr><tr><td>nss- SO₄²⁻</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td><td>ns</td></tr><tr><td>nss-Ca²⁺</td><td>0.67</td><td>ns</td><td>0.45</td><td>0.56</td><td>0.54</td><td>ns</td><td>ns</td><td>0.47</td><td>0.91</td><td>ns</td></tr></tbody></table>