# Fate of trace elements and emerging environmental pollutants (benzotriazoles and benzothiazoles) from a glacier-fed river in the mixing zone of an Arctic fjord system

Joséphine Amey, Øyvind Mikkelsen

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## To cite this version:

Joséphine Amey, Øyvind Mikkelsen. Fate of trace elements and emerging environmental pollutants (benzotriazoles and benzothiazoles) from a glacier-fed river in the mixing zone of an Arctic fjord system. Environmental Chemistry and Ecotoxicology, 2025, 7, pp.339-350. 10.1016/j.enceco.2025.01.001. hal-05104311

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# Fate of trace elements and emerging environmental pollutants (benzotriazoles and benzothiazoles) from a glacier-fed river in the mixing zone of an Arctic fjord system

Joséphine Amey<sup>a</sup>, Øyvind Mikkelsen<sup>b,*</sup>

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## ARTICLE INFO

### Keywords:

Arctic fjord system

Trace metals

Benzotriazoles

Benzothiazoles

Glacier

Sediment

Seawater

## ABSTRACT

The fate of organic and inorganic pollutants was studied in the Arctic, in the mixing zone of freshwater and seawater of a glacier-fed river and a fjord (Ny-Ålesund, Svalbard). Concentrations of trace elements and contaminants of emerging concern, benzotriazoles and benzothiazoles (BTRs and BTHs), were assessed. Metal concentrations of Al, As, Cr, Hg, Mo, Ni, Pb, Sb, Sn, V, and Zn in marine sediment were up to two or three times higher than in riverine sediment and most of them showed an increasing trend from the upper to the lower part of the river. Pb (0.058 µg/L) and Zn (0.80 µg/L) were present in levels of moderate pollution in seawater close to town, while Cu (0.11 µg/L) exceeded background levels in the same area. As (0.042 µg/L), Hg (0.004 µg/L) and Cd (0.011 µg/L) showed levels of low to moderate pollution in freshwater from the river. In seawater and river water detected BTRs and BTHs were: BTR, TTR, 2-OH-BTH, XTR, 2-Me-S-BTH, 2-M-BTH, 2-S-BTH, and 2-NH₂-BTH. Considerably high concentrations of BTR (1460 ng/L) and 2-OH-BTH (1070 ng/L) were found. Compounds present in marine and riverine sediment were BTR, 2-OH-BTH, 2-Me-S-BTH, and 2-M-BTH. Sediment appeared to be a significant sink of BTRs and BTHs with a concentration range of 1.13–32.7 ng/g. A trend of higher concentrations of trace elements in sediment (ANOVA, *p* = 0.044) and seawater (ANOVA, *p* = 0.013), as well as 2-OH-BTH in seawater (*t*-test, *p* = 0.010) was observed in the vicinity of the town, where most anthropogenic activities have taken place due to former mining operations.

## 1. Introduction

Organic pollutants are known to be persistent in Arctic environments and can, together with trace metals and metalloids, bioaccumulate and biomagnify in Arctic wildlife with highly toxic effects [1–3]. Changing climate conditions have resulted in glacier melting and permafrost thawing, which can contribute to the release of pollutants into aquatic systems and eventually increase their bioavailability [2,4,5]. Arctic regions receive long-range transported pollutants originating e.g., from atmospheric deposition and oceanic currents. Trace metals originate from natural local sources like parent materials or from anthropogenic sources like fossil fuel combustion and waste incineration [2,6,7]. They can be transported over long distances via the atmosphere, in gaseous or particulate form, and tend to accumulate in ice and snow in the Arctic. The accumulation of trace metals takes place especially over the wintertime due to the cold and dense air that makes them condensate

and precipitate [2,3,8]. Other matrices in the Arctic where trace metals were detected are vegetation and soils. During the spring melting season, trace elements are released into glacier-fed rivers, which transport them into fjord systems and subsequently into the ocean. Commonly found metals are mercury, cadmium, and copper among many others [2,6].

BTRs and BTHs are two groups of organic pollutants with metal complexing properties and are therefore mainly used as corrosion inhibitors [9,10]. These heterocyclic aromatic compounds, considered contaminants of emerging concern (CECs), are highly water soluble and likely to be transported by ocean currents and rivers [11]. Yearly, 78 tons of BTRs and BTHs flow through rivers from central Europe to the North Sea, presenting a potential source of BTRs and BTHs of long-range transport [12]. BTRs and BTHs are chemicals produced in high volume since the late 1950s for a versatile use in industries and consumer products [13]. BTRs are typically used in de-icing/anti-icing fluids,

<footnote><sup>a</sup> Aix Marseille Univ, LCE, Marseille, France</footnote>

<footnote><sup>b</sup> Department of Chemistry, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway</footnote>

<footnote>* Corresponding author.</footnote>

<footnote>E-mail address: oyvindm@ntnu.no (Ø. Mikkelsen).</footnote>
especially for aircrafts, in cooling and hydraulic fluids, in dishwasher detergents, and as ultraviolet light stabilizer for plastics [12,14,15]. BTHs are used in rubber manufacturing, de-icing/anti-icing fluids, in various pesticides, drugs, and food flavors [14,16]. Correlations between BTRs and BTHs, and trace metals would indicate a common source or origin [9,10].

In the Arctic, the fate of trace elements and persistent organic pollutants (POPs) such as BTRs and BTHs, entering the mixing zone of fresh and salt water is poorly studied. It has been shown that the speciation of trace metals depends on many different factors, such as salinity, temperature, pH, turbidity, etc., which contribute to whether these elements adsorb onto particles and accumulate in the sediment or are released into the seawater. Previous studies revealed that glaciers contribute to the release of trace elements [8,17]. In the last 40 to 50 years, the ice cover of Svalbard (Arctic Archipelago) decreased by 2 %, which implied the loss of 600 km² of glacier fronts. Glacier meltwater has high sediment loads and loses the sediment gradually once it reaches seawater [18].

This study intends to analyze the fate of BTRs, BTHs and trace metals in the mixing zone of freshwater and seawater, as well as possible correlations between these organic and inorganic species. In general, data about BTRs and BTHs is scarce to non-existent for Arctic regions [19]. For the first time (to the best of our knowledge) the presence and behavior of BTRs and BTHs in relation with trace elements were assessed in an Arctic fjord system.

# 2. Materials and methods

## 2.1. Study area

The study area is located at 78°55'30"N, 11°55'20"E in the surroundings of Ny-Ålesund, on the west coast of the island of Spitsbergen (Fig. 1). Spitsbergen is part of the Svalbard archipelago in the Arctic Ocean. Ny-Ålesund is the world's northernmost year-round research station, which in the past was a coal mining town from 1916 to 1963

[20,21].

Ny-Ålesund is situated on the southern shore of Kongsfjorden, a fjord with a length of 6.4 km and widths ranging between 6.4 and 14.5 km [22]. Near Ny-Ålesund, two glaciers, Vestre and Austre Brøggerbreene, have run-offs in the summer that lead into the fjord via the Bayelva River (Fig. 1). The glacier Austre Brøggerbreen is one of the glaciers with the highest negative cumulative mass balance over the period of 1967 up until today [18]. Kongsfjorden, with depths close to 350 m, has a deep continental shelf connected to the open sea, allowing seawater from the Arctic Ocean to enter easily. Thus, the water in the fjord is mainly dominated by Arctic water and surface water. The bathymetry of Kongsfjorden changes constantly due to moving sandbanks influenced by currents and riverine inputs [18].

## 2.2. Sample collection

### 2.2.1. Sampling in Kongsfjorden

Sampling of seawater and sediment was carried out on the 25th and 26th August 2022. Samples were taken at eleven locations (Fig. 2) in Kongsfjorden near the river mouth of Bayelva. Information regarding the geo-coordinates of the sample locations and sample types is given in Table S1 (Supporting Information SI). Before the actual sampling, conductivity, temperature, and depth (CTD) measurements, including turbidity, were carried out using a CTD device (model SD204, SAIV A/S, Bergen, Norway). The water samples were taken at each location with two Niskin bottles, one at one meter below the sea surface, and one at one meter above the sea bottom (12 l volume, PVC, metal free, KC Denmark A/S). The water samples were collected in polypropylene (PP) tubes of 15 ml (for trace elements) and 50 ml (for BTRs and BTHs), three replicates for each sample. Sediment samples were collected with a VanVeen grab at up to 60 m depth and stored in the 50 ml PP tubes for both, metals and BTRs and BTHs. Nitrile gloves were worn during sampling.

The 15 ml seawater samples for trace element analysis were filtered by using a syringe (50 ml, HENKE-JECT®) with a 0.45 µm pore size

<figure><img src="image_5.png" /><figcaption>Fig. 1. Map of sampling points in Kongsfjorden and Bayelva River in the area of Ny-Ålesund.</figcaption></figure>
<figure><img src="image_6.png" /><figcaption>**Fig. 2.** Map of sample locations showing the method used to analyze concentrations in terms of distance in two rows starting from the upper part of Bayelva (BU) towards the lower part of Bayelva (BL).</figcaption></figure>

polyethersulfone (PTFE) membrane filter and acidified to pH < 2 with ultra-pure nitric acid (14.4 M, prepared inhouse using SubPUR Milestone distillation system). A list of all chemicals and materials used can be found in Table S2 (SI). All samples were stored at –20 °C.

### 2.2.2. Sampling at the Bayelva River

Freshwater and fluvial sediment samples were taken at two different locations along the Bayelva River (Fig. 2). Sampling at the first location took place on the 27th August at the upper part of the river (BU) at 78°54′56.94″ N, 11°50′00.69″ E near the glacier Vestre Brøggerbreen. Sampling at the second location, the lower part of Bayelva (BL), closer to the river mouth, was carried out on the 28th August at 78°55′18.41″N, 11°49′30.62″E. For trace element analysis the water was filtered in situ into 15 ml PP tubes and acidified to pH < 2 with ultra-pure nitric acid (14.4 M, prepared inhouse using SubPUR Milestone distillation system), while for BTRs and BTHs volumes of 50 ml were sampled. The samples were stored at –20 °C.

## 2.3. Analysis of trace elements

### 2.3.1. Sample preparation of seawater and freshwater samples

For trace element analysis, 40 seawater samples were prepared by preconcentrating and removing the matrix with SeaFAST (ESI, Omaha, U.S.A.) before the analysis with ICP-MS (Agilent 8800). A total of six freshwater samples were analyzed with ICP-MS without pretreatment, along with three field blanks of the seawater samples. These blanks were placed in a plastic cup fixed on a mount on the vessel where the sampling took place. The field blanks were exposed for the duration of the sampling, which was approximately 25 min per sample location.

### 2.3.2. Sample preparation of sediment samples

Frozen sediment samples were freeze-dried (ALPHA 1–4 LD Plus, CHRIST GmbH) for 177 h (main drying phase) until reaching a pressure of 0.94 mbar. Matrix digestion of sediment samples was carried out with UltraCLAVE (Milestone GmbH, Leutkirch, Germany) with nitric acid (AnalaR NORMAPUR®, VWR). Therefore, ~300 mg freeze-dried sediment was weighed out into Teflon™ tubes and 9 ml of HNO₃ 50 % (prepared by sub-boiling distillation of 65 % HNO₃ (AnalaR NORMAPUR®, VWR)) were added to each tube. In addition to the sediment samples, three solvent blanks containing 9 ml HNO₃ 50 % were included as well as certified reference material (MESS-4 and BCR-277R). The rack with the Teflon™ tubes was placed into a container with a solution of sulfuric acid and hydrogen peroxide (320 ml Milli-Q water, 30 ml H₂O₂ (30 %, AnalaR NORMAPUR®, VWR), 2 ml H₂SO₄ (96 %, Suprapur, Merck)). Once the process was completed the samples were diluted with ultrapure water (~18.2 MΩ·cm) to achieve a final HNO₃ concentration of 0.6 M.

### 2.3.3. Analysis with ICP-MS

Samples were analyzed for elemental composition using 8800 Triple Quadrupole inductive coupled plasma mass spectrometry (ICP-MS) system (Agilent, USA) equipped with prepFAST M5 autosampler (ESI, USA). Accuracy of the analysis was determined using certified reference materials (BCR-277R and MESS-4). System parameters during analysis are to be found in Table S3 (SI).

## 2.4. Analysis of BTRs and BTHs

### 2.4.1. Sample preparation of water and sediment samples

Water samples were adjusted to pH < 3 with HCl (37 %, AnalaR NORMAPUR, VWR®) and filtered with glass microfiber filters
(Whatman®, 47 mm) to separate the particulate phase from the liquid phase. The filters were frozen and then freeze-dried for 24 h (ALPHA 1–4 LD Plus, CHRIST GmbH). Sediment samples were the same freeze-dried samples as used for trace metals. Filters and sediments (~0.1 g each sample) were placed in 15 ml PP tubes to which 5 ml of solvent (MeOH: acidified H₂O) and 10 µL of internal standard (IS) were added. The filters were put in an ultrasonic bath (Branson 3510 Ultrasonic Cleaner) for partitioning. Subsequently, the tubes were centrifuged and the resulting liquid phase was taken out with a glass pipette into new 50 ml PP tubes that were topped up with acidified water. To the filtered water samples in 50 ml PP tubes, 10 µL of the IS were added.

The isolation of the target analytes was achieved by solid-phase extraction (SPE) with SPE-cartridges (Strata-X 33 µm Polymeric Reverse Phase, 200 mg, 6 ml, Phenomenex). TurboVap (Biotage TurboVap® LV Concentration Workstation) was used to concentrate the samples to a volume of 250 µL and the vials were topped up to 1 ml with a mix of MeOH: ACN + 1 % formic acid. A procedure blank of distilled water was added to each set of samples that was prepared for analysis.

### 2.4.2. Analysis with LC-MS/MS

The group of BTHs analyzed in this study included benzothiazole (BTH), 2-hydroxybenzothiazole (2-OH-BTH), 2-(methylthio)benzothiazole (2-Me-S-BTH), 2-mercapto benzothiazole (2-S-BTH), 2-aminobenzothiazole (2-NH2-BTH), 2-morpholin-4-yl-benzothiazole (2-M-BTH), 2-chlorobenzothiazole (2-Cl-BTH), 2-thiocyano-methylthio-benzothiazole (2-SCNMeS-BTH), 2-methylbenzothiazole (2-Me-BTH). The group of BTRs analyzed was composed of benzotriazole (BTR), 4-methyl-1H-benzotriazole, benzotriazole-d4 (BTR-d4), 5,6-dimethyl-1H-benzotriazole monohydrate (XTR), 1-hydroxybenzotriazolehydrate (1-OH-BTR), benzotriazole-5-carboxyl acid (BTR-COOH), 5-amino-1H-benzotriazole (5-amino-BTR), 5-chlorobenzotriazole (5-Cl-BTR).

The target analytes were detected with an Acquity UPLC system (IClass) coupled to a Xevo TQ-S (triple quadrupole (QqQ)) mass spectrometry system (Waters, Milford, U.S.), by adapting the method for BTRs and BTHs from Wang et al. (2016) [23]. Optimized inhouse method was applied for UPLC-Xevo-TQ-S instrument [19].

The chromatograph was equipped with a Kinetex C18 column (30 × 2.1 mm, 1.3 µm, 100 A Phenomenex) and serially connected to a Phenomenex guard column (C18, recommended for 2.1 mm ID columns). The analysis was carried out with the mass analyzer in ESI positive mode, at a column temperature of 30 °C, an injection volume of 5 µL and a flow rate of 0.4 µL/min. The mobile phase consisted of two phases – the water phase contained water with 0.1 % of formic acid (A) and the organic phase acetonitrile with 0.1 % formic acid (B), while the solvent for washing was 96 % ethanol. General parameters are listed in Table S4 (SI).

### 2.4.3. Data analysis of BTRs and BTHs

Chromatograms and data were obtained using the software MassLynx V4.1 from Waters™ and were analyzed in MRM mode.

### 2.4.4. Quality assurance and quality control

Calibration curves for BTRs and BTHs were prepared with BTR-d4 as IS in MeOH: H₂O and 1 % formic acid at eleven concentrations ranging from 0.01 ppb to 50 ppb. Calibration curves for water and sediment samples presented a linearity with regression coefficients >0.99. Limits of detection (LODs) and limits of quantification (LOQs) were obtained by using the signal-to-noise ratios (S/N) of three and ten times the noise, respectively. LODs for marine and fluvial sediments were in the range of 0.33–3.3 ng/g, with LOQs of 1.0–10 ng/g (Table 2). For freshwater and seawater, LODs were in the range of 0.33–5.0 ng/L and LOQs of 1.0–15 ng/L (SI Table S8). The results were consistent with those of Asimakopolus et al. (2013) [14]. The relative standard deviation exceeded 20 % for most compounds, except for BTR and 2-M-BTH (SI Table S5). Recoveries (%) of the target compounds have been previously reported by Asheim et al. (2019). All concentrations of BTRs and BTHs were blank

subtracted.

## 2.5. Statistical analysis

Principle component analysis (PCA) was conducted with the software Aspen Unscrambler V12.1 for various data sets. Points that are found in clusters reflect a similar variability in their data, which in the case of trace metals and BTRs and BTHs could suggest a common source or origin. Statistical analyses were performed using the DATAtab software, including Spearman's correlation, ANOVA, and Student's t-tests. Data sets that did not meet the assumption of normality were standardized using the Box-Cox transformation method in DATAtab. Statistical significance was determined at a significance level of α = 0.05 for all analyses. The PCA and statistical analysis results can be found in Section SA of the SI. River samples were excluded from all statistical analysis due to an insufficient number of samples.

# 3. Results and discussion

## 3.1. CTD parameters

CTD measurements in Kongsfjorden confirmed the presence of a salinity gradient in the mixing zone of freshwater and seawater as can be seen in the two salinity profile sections that are parallel to the coast (Fig. 3). However, freshwater discharge during summer is moderate compared to the late spring snow melting season when runoff is a mix of both snow melting and glacier runoff.

Salinity-depth-profiles with the data from all sample locations in Kongsfjorden together showed clear trends of temperature and turbidity along the water column (Fig. 4). Stratification of the water column was due to changing temperatures and to the salinity gradient. The stratification pattern is comparable to the findings of Bazzano et al. (2014) [24]. Increased turbidity in higher stratification layers is characteristic for river water with sediment loads entering the fjord.

## 3.2. Spatial distribution of metals in sediment

The elements Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Sb, Sn, V and Zn, as relevant elements related to pollution in the Arctic, were targeted in sediment samples. Their concentrations at each sampling location are shown in Table 1. Concentrations of the metals were present in marine sediment in the following descending order: Al > Fe > Mn > Zn > V > Cr > Ni > Cu > Pb > Co > As > Sn > Mo > Cd > Sb > Hg. In fluvial sediment the order was as follows: Fe > Al > Mn > Zn > V > Cr > Ni > Cu > Co > Pb > As > Sn > Mo > Cd > Sb > Hg.

The distribution of trace elements in sediments was analyzed in terms of distance to the upper part of Bayelva and in two rows in Kongsfjorden (1st row: P5 to P1; 2nd row: P6 to P10) (Fig. 2). An increase of Al, As, Cd, Co, Fe, Mn, Mo, Ni, Pb, Sb, Sn, V, and Zn was noticeable from the upper part of Bayelva (BU) to the lower part (BL) and towards Kongsfjorden. No concentration pattern between the 1st and the 2nd row, that might be influenced by the salinity gradient, was observed.

As, Cr, Hg, Ni, Pb, Sb, and Zn, classified as priority contaminants by the United States Environmental Protection Agency [25], along with Al, Mo, Sn, and V, had concentrations in sediments from Kongsfjorden that were approximately two to three times higher than those in fluvial sediment from the Bayelva River. The geochemical distribution of metals in sediment is influenced by various physical and chemical factors such as granulometry, redox reactions, adsorption and desorption processes as well as the composition of the sediment itself. Sediments composed of silt and clay present a larger surface area than sand, which allows them to adsorb and retain trace metals from the surrounding water more easily, in the same way they retain organic matter [26–28]. The higher presence of organic matter in silt and clay can enhance the formation of complexes with metals and further increase the
<figure><img src="image_7.png" /><figcaption>**Fig. 3.** A: Vertical profiles of sample locations in Kongsfjorden that were (A) closest to the shore (P1, P2, P3, P4, and P5), and (B) further out in Kongsfjorden (P7, P9, and P10), showing the salinity gradient in relation with the depth. Generated with the Ocean Data View (Schlitzer, Reiner, Ocean Data View, odv.awi.de, 2023).</figcaption></figure>

concentration of trace metals [28]. This phenomenon is particularly characteristic in the mixing zones of glacier-fed fjords, where the settling of fine-grained sediments, primarily composed of silt and clay, occurs [28,29]. In this study, visual inspection revealed that silt and clay dominated the mixing zone, likely explaining the higher metal concentrations in Kongsfjorden, whereas river sediments consisted primarily of fine to coarse sand. Additionally, sediments of the mixing zone in Kongsfjorden are prone to receive larger amounts of metals of anthropogenic origin (from local anthropogenic activities and ocean currents (LRT)) [2,7,19,22,30], while river sediments receive their metal inputs mainly from the bedrock, glacier water and snow melt [2,6,31]. Another factor that can enhance the accumulation of metals in sediment is the presence of Mn or Fe oxides that play an important role in scavenging processes, especially for V [32,33].

The sampling locations closest to the town (P1, P2, P9, and P10) presented increased concentrations of metals, including As, Cd, Co, Cu, Cr, Hg, Mo, Pb, Sb, Sn, V, and Zn (ANOVA, *p* = 0.044). In addition, increased concentrations of Al (t-test, *p* = 0.043) and Fe (t-test, *p* = 0.063) were observed at these locations. This locally concentrated presence of these metals could be an indicator of local anthropogenic pollution. These elements are associated to many sources such as former mining activities, traffic, diesel combustion, wastewater, etc. [2,7,22,30]. It is important to note that trace metals tend to accumulate in sediment and can be released again over long periods of time [34–36]. Interestingly, the sampling location P6 was supposedly the one furthest away from local anthropogenic pollution (from town) and presented the lowest overall metal concentrations in Kongsfjorden. This difference was statistically significant (ANOVA, *p* = 0.007).

The concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and Hg in

Table 1 are consistent with the results of sediment samples taken in Kongsfjorden in July 2009 [37]. Lu et al. (2013) associated Hg, Cd, Pb, and Zn partly to anthropogenic pollution indicated by the enrichment factor analysis. A report published by the Geological Survey of Norway presented values for marine sediment in Kongsfjorden from 2017 and 2018, in which Cd levels were remarkably lower (0.05–1 µg/g) [38] compared to the results of this recent study. In this study, the concentrations of Hg found in marine sediment from Kongsfjorden were consistent with those reported in several studies conducted in the Arctic Ocean [39].

According to the quality standards set by the Norwegian Environmental Agency for the classification of environmental conditions of sediment, all listed trace metals of fluvial and marine sediments were within background levels, except Cd, which showed a small degree of contamination (class 2) in marine sediment at P10, and Hg at locations P8 and P9 [40]. These findings align with those reported by Sagar et al. (2021), who characterized the sediment in the area nearby as presenting minor enrichment of trace metals.

### 3.3. Spatial distribution of metals in water

The concentrations of Cd, Co, Cu, Fe, Mn, Ni, Pb, V, and Zn were assessed in surface water at one meter depth and in bottom seawater, one meter above the seafloor, and are listed in Table S6a (SI) for each sample location. SEAFast presented limitations in the analysis (recoveries) of trace metals, hence the limited number of metals analyzed in seawater. Concentrations of Al, As, Cd, Co, Cu, Cr, Fe, Hg, Mn, Mo, Ni, Sb, Sn, V, and Zn in freshwater are presented in Table S6b (SI).

The spatial distribution of trace metals in water was assessed by
<figure><img src="image_8.png" /><figcaption>Fig. 4. (A) Depth-Temperature-Salinity and (B) Depth-Turbidity-Salinity profiles of all sample points combined (P1, P2, P3, P4, P5, P7, P9, P10). Generated with the Ocean Data View (Schlitzer, Reiner, Ocean Data View, odv.awi.de, 2023).</figcaption></figure>

comparing freshwater from Bayelva with surface seawater from Kongsfjorden. Fe, Cu, V, and Zn were present in significantly higher concentrations in seawater, whereas Mn and Ni were two to four times more concentrated in river water. This difference may be attributed to the parent material from the Eastern Brøggerdalen area [41,42]. Interestingly, Cd also had the highest concentration in freshwater at BU, which is rather associated to anthropogenic sources and atmospheric deposition [6,43]. The sheltered valleys formed by the Austre and Vestre Brøggerbreene glaciers are particularly prone to pollution from atmospheric transport, as they are exposed to strong winds coming from the sea towards the mountains, where the winds collapse. This allows large amounts of dust, potentially carrying trace metals and other pollutants, to settle [43].

Based on the classification of heavy metals for freshwater and coastal seawater provided by the Norwegian Environmental Agency, the measured Cd concentration indicated a low degree of contamination, as did the concentrations of As and Hg in freshwater, pointing towards anthropogenic pollution in the Bayelva River [40]. Other metals that were within background levels can be explained by the local bedrock mineralogy and are consistent with expected values from parent material and other natural sources [40,44,45].

Surface seawater showed consistently higher concentrations of metals, a trend that was also observed for organic compounds (SI Fig. SA4). Comparing metal concentrations in surface and bottom water (Fig. 5) revealed higher concentrations of Cd, Co, Cu, Fe, Mn and Ni in surface water (ANOVA, *p* = 0.002), likely due to their behavior as scavenged elements [46,47]. The locations close to town (P1, P2, P9, P10) presented elevated concentrations of Co, Fe, Mn, Ni, Pb, and Zn in bottom water. This might indicate a potential underwater leakage of metals either from the sediment itself or from anthropogenic sources, such as the old dump site in the little bay (Thiisbukta) between Ny Ålesund and the airport (same as the sampling site) (Fig. 2). This dump site is a significant pollution source of both, organic and inorganic contaminants [7]. Pb, with a maximum value of 2.24 µg/L at P2, is

classified as moderate contamination, according to the Norwegian Environmental Agency. Similarly, Zn, with a concentration of 5.97 µg/L at P10, falls within class 3 (moderate pollution) but is near the threshold for class 4 (severe pollution) [40]. In general, the largest inputs of V originate from continental dust and fossil fuel combustion [48]. V was generally higher in bottom water and could originate from leaching sediment, where it might have accumulated over time, mainly from continental dust. It has been observed that dissolved V in pore water is quickly removed from the dissolved phase during early diagenetic processes through surface adsorption or the formation of insoluble oxides. This can create a diffusive flux of V from the overlying water column to sediment, which can lead to elevated concentrations of V in bottom water [32].

Cu, present in levels of low contamination [40], presented an irregular pattern of spatial distribution. After Krause et al. (2021), the distribution of dissolved Cu cannot entirely be explained by the salinity gradient [41]. The same study highlighted that in the mixing zone of freshwater and seawater, dissolved Co, Fe and Ni decrease linearly with increasing salinity [41]. In this study, only Ni confirmed this trend while Fe and Co were not decreasing with increasing salinity. Bazzano et al. (2014) observed negative correlations between trace metals and salinity while analyzing suspended particulate matter from Kongsfjorden [24]. It is important to note that the present study focused exclusively on the dissolved fraction of metals, and therefore cannot be directly compared to the results of Bazzano et al. (2014). Further findings of Bazzano et al. (2014) showed that Cr, Cu, Mn, Mo, Ni, Pb, and Zn were mainly introduced into Kongsfjorden by Atlantic Water carried by the West Spitsbergen Current while Al, Co, Fe and V originated from the glaciers in the form of natural inputs.

Sources of trace metals from long-range transport are well known, such as industrial sites like Norilsk, which has the world's largest heavy metal smelting complex, releasing over four million tons of As, Cd, Cu, Ni, Pb, and Zn into the atmosphere each year [43]. Other long-range pollution sources, though closer in proximity, include settlements on
<table><caption>**Table 1**
Mean concentrations of trace metals (µg/g) in sediment of Kongsfjorden (P1-P10) and Bayelva River (BL and BU) and LODs given in µg/L.</caption><thead><tr><th></th><th>Al</th><th>As</th><th>Cd</th><th>Co</th><th>Cu</th><th>Cr</th><th>Fe</th><th>Hg</th><th>Mn</th><th>Mo</th><th>Ni</th><th>Pb</th><th>Sb</th><th>Sn</th><th>V</th><th>Zn</th></tr></thead><tbody><tr><td>P1</td><td>33,300</td><td>5.62</td><td>0.140</td><td>9.01</td><td>12.8</td><td>41.1</td><td>24,800</td><td>0.0182</td><td>328</td><td>0.371</td><td>20.7</td><td>11.8</td><td>0.0453</td><td>0.760</td><td>51.5</td><td>51.0</td></tr><tr><td>P2</td><td>32,500</td><td>5.24</td><td>0.115</td><td>8.81</td><td>12.2</td><td>40.8</td><td>24,100</td><td>0.0243</td><td>329</td><td>0.330</td><td>20.6</td><td>11.2</td><td>0.0488</td><td>0.694</td><td>51.5</td><td>49.0</td></tr><tr><td>P3</td><td>32,500</td><td>4.96</td><td>0.121</td><td>8.92</td><td>12.6</td><td>40.5</td><td>24,600</td><td>0.00417</td><td>318</td><td>0.522</td><td>20.7</td><td>11.7</td><td>0.0524</td><td>0.781</td><td>51.1</td><td>51.8</td></tr><tr><td>P4</td><td>30,200</td><td>4.29</td><td>0.121</td><td>8.27</td><td>11.6</td><td>36.6</td><td>22,000</td><td>0.0108</td><td>339</td><td>0.437</td><td>18.6</td><td>9.93</td><td>0.0477</td><td>0.739</td><td>44.9</td><td>59.6</td></tr><tr><td>P5</td><td>31,400</td><td>5.79</td><td>0.140</td><td>8.68</td><td>12.6</td><td>40.0</td><td>24,300</td><td>0.0202</td><td>285</td><td>0.546</td><td>20.5</td><td>11.2</td><td>0.0654</td><td>0.908</td><td>48.2</td><td>47.8</td></tr><tr><td>P6</td><td>25,009</td><td>4.14</td><td>0.118</td><td>7.09</td><td>8.90</td><td>32.7</td><td>19,200</td><td>n.d.</td><td>294</td><td>0.345</td><td>16.8</td><td>8.55</td><td>0.0573</td><td>0.591</td><td>39.9</td><td>37.3</td></tr><tr><td>P7</td><td>34,400</td><td>5.26</td><td>0.117</td><td>9.25</td><td>11.7</td><td>42.4</td><td>25,000</td><td>0.0145</td><td>357</td><td>0.424</td><td>21.4</td><td>11.5</td><td>0.0450</td><td>0.653</td><td>52.2</td><td>49.9</td></tr><tr><td>P7/8</td><td>32,500</td><td>7.22</td><td>0.108</td><td>9.12</td><td>12.2</td><td>40.7</td><td>25,000</td><td>0.00787</td><td>382</td><td>0.330</td><td>20.8</td><td>11.3</td><td>0.0514</td><td>0.624</td><td>50.3</td><td>48.7</td></tr><tr><td>P8</td><td>31,600</td><td>5.14</td><td>0.099</td><td>8.81</td><td>11.8</td><td>39.6</td><td>24,600</td><td>0.132</td><td>334</td><td>0.300</td><td>20.2</td><td>11.1</td><td>0.0491</td><td>0.611</td><td>48.4</td><td>48.4</td></tr><tr><td>P9</td><td>36,700</td><td>6.59</td><td>0.103</td><td>10.2</td><td>13.7</td><td>45.2</td><td>27,500</td><td>0.180</td><td>375</td><td>0.358</td><td>23.2</td><td>13.0</td><td>0.0396</td><td>0.667</td><td>56.3</td><td>56.5</td></tr><tr><td>P10</td><td>34,600</td><td>5.64</td><td>0.294</td><td>9.47</td><td>12.9</td><td>42.0</td><td>25,800</td><td>0.0263</td><td>341</td><td>0.326</td><td>21.3</td><td>12.1</td><td>0.0431</td><td>0.743</td><td>51.8</td><td>53.1</td></tr><tr><td>BL</td><td>16,600</td><td>2.44</td><td>0.104</td><td>8.09</td><td>12.3</td><td>19.7</td><td>18,800</td><td>0.00675</td><td>294</td><td>0.277</td><td>14.8</td><td>7.91</td><td>0.0251</td><td>0.372</td><td>25.5</td><td>31.4</td></tr><tr><td>BU</td><td>16,500</td><td>1.97</td><td>0.092</td><td>7.76</td><td>10.5</td><td>19.9</td><td>17,600</td><td>0.00950</td><td>261</td><td>0.248</td><td>13.9</td><td>6.55</td><td>0.0188</td><td>0.312</td><td>24.2</td><td>30.4</td></tr><tr><td>LOD</td><td>0.184</td><td>0.000550</td><td>0.000531</td><td>0.00215</td><td>0.00296</td><td>0.0100</td><td>0.00835</td><td>0.00241</td><td>0.00258</td><td>0.00108</td><td>0.00222</td><td>0.000534</td><td>0.000726</td><td>0.00226</td><td>0.000731</td><td>0.000217</td></tr></tbody></table>

Spitsbergen itself, such as Longyearbyen, a former mining town with 2400 inhabitants (2019) and approximately 150,000 visitors each year [49]. Many visitors reach Spitsbergen by cruise ships, contributing to environmental impacts through fossil fuel combustion and increased sewage effluent. Even though all mines in Longyearbyen are closed today, one mine remained active until 2023, and coal was burned for the local energy supply releasing heavy metals to the atmosphere. The other larger settlement on Spitsbergen is Barentsburg, which is still an active mining site with 500 inhabitants, contaminating through coal mining and related activities [7].

A study of trace metals of a fjord at the south of Spitsbergen Island (Hornsund) presented significantly higher concentrations (in August) of Cd (20–198 ng/L) and slightly higher concentrations of Cu (438–1611 ng/L) and Zn (3097–13,466 ng/L) while Pb concentrations were consistent [5]. Zaborska et al. (2020) found that dissolved metal concentrations of Cd, Cu, Pb and Zn in the fjord were highest during the melting season (Cd in May/others in June), which was attributed to the release of trace metals from glaciers, ice, snow, and soil [5]. The higher metal concentrations observed in Hornsund may be explained by its southern location, where metals might settle first when carried towards the Arctic by atmospheric transport.

### 3.4. Spatial distribution of BTRs and BTHs in sediment

The concentrations of BTRs and BTHs in sediment (Table 2) were dominated by BTR and 2-OH-BTH. 2-OH-BTH had the highest concentrations near the town of up to 32.7 ng/g (t-test, *p* = 0.010), while BTR was highest at P4 close to the river outlet. 2-M-BTH had comparatively high concentrations at both locations, P4 and P10. An increasing trend in BTR concentrations was observed from freshwater to seawater (BU < BL < SW). These findings, consistent with Hu et al. (2021) [50], revealed that BTRs and BTHs tend strongly to accumulate in sediment. However, Xu et al. (2022) suggested that BTR concentrations in sediments are generally lower than in water due to their low octanol/water partition coefficient (log K<sub>OW</sub>) [51].

The accumulation of 2-M-BTH and 2-Me-S-BTH in sediment can be attributed to their lower solubility and higher hydrophobicity, as reflected in their elevated log K<sub>OW</sub> values (SI Table S7). These properties likely explain the accumulation of these two compounds in sediment. In contrast, the more hydrophilic and water-soluble compounds, BTR and 2-OH-BTH, may accumulate in sediments due to the rapid settling of fine sediments. This process could potentially entrain these compounds, initially present in high concentrations in river and seawater. Few correlations of BTRs and BTHs with trace metals were observed (Fig. SA1). Notably, 2-M-BTH showed positive correlations with Zn, Sn, and Cd (*p* = 0.72–0.79), which may be associated with sewage effluents or other anthropogenic activities (e.g., harbor or dump site of Thiisbukta) [7].

A study from China presented sediment concentrations of BTR ranging between 15.3 ng/g and 97.5 ng/g and BTH concentrations of up to 132 ng/g at the Pearl River Delta, which is one of the most developed and urbanized areas in China receiving high rates of sewage water [51]. Comparing these values to the present results of sediment from Bayelva, maximum concentrations of BTR and 2-OH-BTH were 2.98 ng/g and 10.1 ng/g, respectively. Overall, data about BTRs and BTHs in sediment is scarce [52].

### 3.5. Spatial distribution of BTRs and BTHs in water

Concentrations of BTRs and BTHs, along with detection limits and detection rates in seawater and river water, are shown in Table S8 (SI). 2-OH-BTH and BTR concentrations were considerably higher than those of all other detected compounds, particularly near the town and the river outlet (P5 and P6) (Fig. 6). These two compounds were also the most abundant compounds, with detection rates of 100 % and 92.3 %, respectively. BTR was remarkably high (BU: 363 ng/L; BL: 1460 ng/L) in freshwater of Bayelva, exceeding concentrations measured in seawater
<figure><img src="image_9.png" /><figcaption>Fig. 5. Illustration of concentration ratios of Co, Cu, Ni, Pb, and V in surface and bottom water of Kongsfjorden.</figcaption></figure>

<caption>**Table 2**</caption>

Mean concentrations (ng/g) and detection rates (DR) in % of BTRs and BTHs in sediment with LODs and LOQs given in ng/L.

<table><thead><tr><th>Location</th><th>BTR</th><th>2-OH-BTH</th><th>2-Me-S-BTH</th><th>2-M-BTH</th></tr></thead><tbody><tr><td>P1</td><td>8.66</td><td>n.d.</td><td>*0.722</td><td>1.70</td></tr><tr><td>P2</td><td>11.5</td><td>n.d.</td><td>*0.798</td><td>&lt;LOD</td></tr><tr><td>P3</td><td>10.2</td><td>*7.68</td><td>*0.411</td><td>1.72</td></tr><tr><td>P4</td><td>15.2</td><td>29.2</td><td>1.26</td><td>6.57</td></tr><tr><td>P5</td><td>10.2</td><td>n.d.</td><td>1.13</td><td>*0.577</td></tr><tr><td>P6</td><td>7.29</td><td>n.d.</td><td>*0.563</td><td>&lt;LOD</td></tr><tr><td>P7</td><td>14.7</td><td>*5.54</td><td>*0.381</td><td>&lt;LOD</td></tr><tr><td>P7/8</td><td>11.3</td><td>14.0</td><td>*0.524</td><td>&lt;LOD</td></tr><tr><td>P8</td><td>13.9</td><td>29.8</td><td>1.75</td><td>&lt;LOD</td></tr><tr><td>P9</td><td>9.68</td><td>*7.02</td><td>1.42</td><td>*0.337</td></tr><tr><td>P10</td><td>8.34</td><td>32.7</td><td>*0.492</td><td>5.27</td></tr><tr><td>BU</td><td>*2.39</td><td>10.1</td><td>&lt;LOD</td><td>1.15</td></tr><tr><td>BL</td><td>*2.98</td><td>&lt;LOD</td><td>1.55</td><td>&lt;LOD</td></tr><tr><td>DR (%)</td><td>100</td><td>66.7</td><td>88.1</td><td>81.0</td></tr><tr><td>LOD</td><td>1.00</td><td>3.33</td><td>0.333</td><td>0.333</td></tr><tr><td>LOQ</td><td>3.00</td><td>10.0</td><td>1.00</td><td>1.00</td></tr></tbody></table>

(Fig. 6). These concentrations were comparable to concentrations of BTRs (200-1250 ng/L) found in rivers of central Europe [12]. Wolschke et al. (2011) reported that these BTRs flow into the North Sea, where their concentrations ranged from 1.7 ng/L to 40 ng/L. The decrease of the concentrations from the rivers to the North Sea was associated to dilution in seawater since BTRs are poorly degradable in the marine environment [12].

Elevated concentrations of BTR were also detected in seawater at P2 in close proximity to the town. 2-OH-BTH, a widely used corrosion inhibitor, was observed in high concentrations in seawater, with a maximum observed near the town at P1 and P2 (1070 ng/L and 1030 ng/L, respectively) (Fig. 6) [14,16]. 2-OH-BTH correlated strongly with Co (p = 0.007), Fe (p = 0.002), Mn (p = 0.003) and to some extent with Ni (p > 0.05) (SI Fig. SA2 and SA3), which might reflect a common source or transport route, such as the leaching from urban coastal settings and protective coatings used in harbor installations.

Most organic compounds showed a trend of higher concentrations near the town, where XTR, 2-Me-S-BTH, and 2-S-BTH correlated with Zn

in bottom water (Fig. SA3), potentially originating from common sources such as marine paints and coatings, rubber or plastic debris [53,54].

Altogether, eight compounds of BTRs and BTHs were detected in seawater and freshwater (SI Table S8), while in sediment from Bayelva and Kongsfjorden only four of those eight compounds were present (Table 2). Despite this, the concentrations in sediment were of up to four orders of magnitude higher than in water (fresh- and seawater), indicating that the sediment (fluvial and marine) acts as a significant sink for BTRs and BTHs (SI Table S9).

Vike-Jonas (2021) collected seawater samples from three locations in the open sea on the east side of Svalbard and from one remote location further north at 83° N, where she detected BTHs in surface water and in Atlantic water at depths of up to 3500 m. BTHs were also detected at two out of the three locations near Svalbard, and BTRs were found at one location at a depth of approximately 40 m, within the Arctic water body [19]. These findings suggest that BTRs and BTHs can be transported over long distances and periods, highlighting their persistence in the ocean.

Concentrations of BTR and TTR reported by Vike-Jonas (2021) were 6.90–9.55 ng/L and 1.73–7.38 ng/L, respectively [19], while in Kongsfjorden, the concentrations of these compounds ranged from 1.08 to 849 ng/L (BTR) and 0.580–34.3 ng/L (TTR), respectively. Vike-Jonas (2021) detected BTHs in seawater at the following concentrations: BTH (225 ng/L), 2-S-BTH (7.42–34.4 ng/L), 2-Me-S-BTH (5.75–28.5 ng/L), and 2-M-BTH (0.72 ng/L). In comparison, concentrations in Kongsfjorden were 0.723–17.9 ng/L for 2-Me-S-BTH and 0.587–54.0 ng/L for 2-M-BTH, while 2-S-BTH was detected at only a few locations, ranging from 3.54 to 40.9 ng/L. BTH was absent in the samples from Kongsfjorden, most likely due to its natural oxidation to 2-OH-BTH (up to 1070 ng/L). All compounds of BTRs and BTHs reported by Vike-Jonas (2021) were also detected in water samples from Ny-Ålesund, with the exception of BTH [19]. However, it is important to note that the concentrations from the open sea are being compared to those from a fjord, which has a much greater potential to accumulate pollutants. To the best of our knowledge, the work of Vike-Jonas (2021) is the only study that addresses BTRs and BTHs in Arctic seawater.

In a study assessing BTRs and BTHs in the Yangtze estuary, salinity was suspected to be responsible for the degradation of BTRs and BTHs in seawater, resulting in lower concentrations with increasing salinity

<footnote>* Mean concentrations below LOQ. Concentrations of replicates that were n.d. or <LOD were considered as LOD/2.</footnote>
<figure><img src="image_10.png" /><figcaption>Fig. 6. Illustration of concentration ratios of BTR and 2-OH-BTH in seawater from Kongsfjorden and freshwater from Bayelva.</figcaption></figure>

[55]. Such a trend was not observed in this present study. Surprisingly, the concentrations of BTRs and BTHs found in this study ranged from n. d. up to 1030 ng/L in surface seawater while in surface water (saline water) of the Yangtze Estuary the concentrations ranged from n. d. up to 10.73 ng/L [55].

A cruise ship and several smaller boats were present in and around the sampling area during sample collection in Kongsfjorden. Boats and especially cruise ships may represent potential contamination sources of BTRs and BTHs, since these compounds are commonly found in hydraulic and brake fluids [13,56–58]. Additionally, BTRs and BTHs are in use to prevent paints, plastic and other building materials from yellowing and degradation [13,59]. Several cruise ships dock in Ny-Ålesund during the summer, bringing up to 20,000 visitors annually and increasing the risk of potential releases of BTRs and BTHs into Kongsfjorden [60].

Another potential source is the wastewater from Ny-Ålesund, especially in summer when the number of inhabitants rises to approximately 150 [60]. Even though there is a small and relatively simple wastewater treatment plant since 2015, BTRs and BTHs are known to be only partially removed as they are highly water soluble and resistant to biological degradation [7,14,56,59,61,62]. The use of dishwasher detergents, sunscreens, personal care products, such as cosmetics and shampoos, and the washing of textiles contribute to the release of BTRs and BTHs in wastewater [58,59]. Other sources of BTRs and BTHs include automobiles and machinery through the wear and tear of tires, other rubber materials, and metallic parts, as well as the use of metal-cutting fluids, for example, in construction and harbor activities [9,19,52,59,62].

In Longyearbyen, sewage water from town and from the airport is released untreated directly into the adjacent fjord (170,000 m³/year), along with 100 tons of food waste each year [7]. This provides a significant source of BTRs and BTHs originating from personal care products, pharmaceuticals, cleaning products, and especially de-/anti-icing agents used at the airport, among other chemicals. Also, the settlement of Barentsburg releases untreated wastewater [7]. These two settlements are located along the shores of the fjord Isfjord, which is connected to the Arctic Ocean. When the pollutants are carried out of Isfjorden by currents, they may be subject to the West Spitsbergen Current. This current could carry the pollutants all the way up to Kongsfjorden if the

conditions are favorable. Even though the Arctic is known to act like a sink for all sorts of pollutants of long-range transport [1,24,63], and even though local pollution might also contribute, the question remains whether this alone can explain the unexpected high levels of BTRs and BTHs found in Kongsfjorden in this study.

A study conducted in the Pearl River basin presented concentrations of 2-OH-BTH, BTR, and 2-Me-S-BTH in freshwater samples, in the ranges of 17.3–426 ng/L, 0.32–201 ng/L, and 0.77–48.2 ng/L, respectively [50]. In comparison, freshwater from Bayelva exhibited significantly higher concentrations of BTR (363–1460 ng/L), while 2-OH-BTH (115–130 ng/L) and 2-Me-S-BTH (1.76–10.1 ng/L) were within similar ranges to those observed in the Pearl River Basin. Another study from the Pearl River Delta reported concentrations of BTRs and BTHs in river water of up to 1279 ng/L [64]. As previously mentioned, the Pearl River Delta is subject to high loads of sewage discharge, which is not the case for the Bayelva River. Therefore, the detection of such high concentrations in Bayelva is unexpected.

The sources of BTRs and BTHs found in Bayelva remain uncertain. Possible sources include the airport, even though no de-icing agents are used, and a sand pit near Lake Tvillingvann, where trucks and wheeled loaders operate to extract raw materials [65] (Fig. 2). This sand pit area has runoff into the Bayelva River (near BU) which could have led to sediment and water contamination over the years. During the coal mining period from 1916 to 1963, mining waste was deposited next to the mines in spoil heaps. In 1963 when the mining town was closed and the inhabitants left Ny-Ålesund, all the waste and eventually old machinery was also left in those spoil heaps and other dump sites. A dump site named Kolhaugen and a former mining site named Vestre Senterfelt (operated from 1960 to 1963) are located close to the Bayelva River in the area of Tvillingvann (Fig. 2) [7,66,67], and may be potential sources of BTRs and BTHs. Sulfuric acid is produced in the heaps, which causes metals to dissociate and accumulate in runoff. Until today it is unknown what is to be found in those heaps, but since BTRs and BTHs were in use since the 1950s, these pollutants might eventually have been released together with metals in the so-called "acid mine drainage" [13,66]. Recently, significant contamination of PFAS/PFOS was discovered in and around the center of Ny-Ålesund, dating back to the late 1980s, caused by the use of firefighting foam during an oil spill at the tank facility [68]. This shows how contamination from past incidents can
continue to surface even today.

Another possible pathway for BTRs and BTHs to reach Bayelva and Kongsfjorden might be the atmosphere. According to models of Arctic Contamination Potential (ACP) for organic compounds, BTRs and BTHs do not tend to be long-range transported via the atmosphere because of their high water solubility and low log KOW (SI Table S7) [69]. However, organic compounds with an octanol/air partition coefficient (Log KOA) > 10 are usually deposited with atmospheric particles before reaching the Arctic [69], which is the case for 2-M-BTH and 2-NH2-BTH (SI Table S7). In turn, the compounds BTR, TTR and 2-S-BTH can be considered as semi-volatile according to their Henry's law constant and vapor pressure (SI Table S7) [70]. This might explain the elevated presence of BTR at BU and BL, as well as the relatively high concentration of TTR in surface water at P6 (34.2 ng/L). In fact, BTR and TTR showed a trend of higher concentrations in surface water (ANOVA, *p* = 0.022). In contrast, the high concentration of 2-M-BTH (54.0 ng/L) in surface water at P6 is likely attributed to nearby sources. Some studies have found concentrations of BTRs and BTHs in particulate matter of outdoor air samples nearby industrial sites [71,72]. Another study found BTRs and BTHs in rain and snow samples, with a maximum concentration of BTH in rain of 70 ng/L [73]. These findings highlight the potential for BTRs and BTHs to be transported via the atmosphere [71–73]. However, this raises the question of whether BTRs and BTHs could be carried by air all the way to the Arctic from Europe or other regions. A more likely pathway for atmospheric transport of these compounds could be through sea spray [74–77].

## 4. Conclusions

This study examined the fate of trace elements, BTRs and BTHs in the mixing zone of freshwater and seawater of a glacier-fed river and an Arctic fjord. Trace metals, BTRs, and BTHs were found in the water and sediment of Kongsfjorden and the Bayelva River. Marine sediment had higher loads of metals compared to river sediments. The trace metals As, Hg and Cd presented a low degree of contamination in freshwater from Bayelva, while in Kongsfjorden, Pb and Zn reached levels of moderate pollution and Cu exceeded background levels. Cd and Hg were enriched in marine sediment. BTRs and BTHs were found in high concentrations in river and seawater, especially BTR and 2-OH-BTH. Both, river and seawater contained eight compounds of BTRs and BTHs while in marine and riverine sediments only four of these were present. Marine and riverine sediments proved to be a significant sink for BTRs and BTHs, demonstrating the potential of these relatively polar compounds to accumulate there. BTRs and BTHs were generally more abundant in marine sediments, although 2-OH-BTH was unexpectedly high in the upper part of the Bayelva River. The pathways of BTRs and BTHs to these compartments (fluvial and marine sediment and fresh- and seawater) remain uncertain and more studies are needed to confirm the concentrations found in Bayelva and Kongsfjorden. The distribution of trace elements and BTRs and BTHs was not affected by the salinity gradient. A spatial distribution pattern of higher concentrations of both, organic and inorganic species in seawater was observed in relation to the proximity to town, as well as to the river outlet. Ultimately, this study revealed for the first time the presence of BTRs and BTHs in an Arctic fjord system and therefore provides a good set up for future studies.

### CRediT authorship contribution statement

**Joséphine Amey:** Writing – original draft, Visualization, Validation, Investigation, Formal analysis, Data curation, Conceptualization.
**Øyvind Mikkelsen:** Writing – review & editing, Supervision, Resources, Project administration, Conceptualization.

### Declaration of competing interest

The authors declare that they have no known competing financial

interests or personal relationships that could have appeared to influence the work reported in this paper.

### Acknowledgements

Susana Villa González for the analysis of organic compounds, Kyyas Seyitmuhammedov and Anica Simic for the analysis of inorganic compounds, at the Department of Chemistry, Norwegian University of Science and Technology (NTNU).

## Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.enceco.2025.01.001.

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