Mechanistic Insight into the Uptake and Fate of Persistent Organic Pollutants in Sea Ice

Garnett, Jack; Halsall, Crispin J.; Thomas, Max; France, James L.; Kaiser, Jan; Graf, Carola; Leeson, Amber; Wynn, P.

doi:10.1021/acs.est.9b00967

Cited by 23 publications

(40 citation statements)

References 27 publications

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“…These findings are also supported by previous studies in sea ice which display similar findings for hydrophobic POPs of varying molecular mass and aqueous solubility. 13 Partitioning of PFAS to ice surfaces can be linked to hydrophobic interactions, which increase with carbon chain length. Interestingly, differences were also observed between PFAS with the same carbon chain length (e.g., 6:2 FTSA, PFOS, and PFOA) which shows that other physicochemical properties also control the their behavior in sea ice, such as the number of fluorine atoms and different functional groups.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, experimental studies in artificial sea ice also showed elevated levels of organic pollutants in brine and demonstrated their distribution in newly formed bulk sea ice was primarily due to the movement of brine. 13 Furthermore, α-HCH was released at a faster rate from melting sea ice compared to less soluble chemicals (i.e., BDE-47, BDE-99), suggesting that partitioning of chemicals between internal solid ice surfaces and liquid brine was also an important process. Due to their known surface acting properties, we anticipate PFAS to display partitioning within sea ice which could result in their enrichment, presenting a motivation to undertake similar experiments to investigate their behavior during sea ice formation and subsequent melt.…”

Section: Introductionmentioning

confidence: 99%

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Investigating the Uptake and Fate of Poly- and Perfluoroalkylated Substances (PFAS) in Sea Ice Using an Experimental Sea Ice Chamber

Garnett

Halsall

Thomas

et al. 2021

Environ. Sci. Technol.

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Poly- and perfluoroalkyl substances (PFAS) are contaminants of emerging Arctic concern and are present in the marine environments of the polar regions. Their input to and fate within the marine cryosphere are poorly understood. We conducted a series of laboratory experiments to investigate the uptake, distribution, and release of 10 PFAS of varying carbon chain length (C 4 –C 12 ) in young sea ice grown from artificial seawater (NaClsolution). We show that PFAS are incorporated into bulk sea ice during ice formation and regression analyses for individual PFAS concentrations in bulk sea ice were linearly related to salinity ( r 2 = 0.30 to 0.88, n = 18, p < 0.05). This shows that their distribution is strongly governed by the presence and dynamics of brine (high salinity water) within the sea ice. Furthermore, long-chain PFAS (C 8 –C 12 ), were enriched in bulk ice up to 3-fold more than short-chain PFAS (C 4 –C 7 ) and NaCl. This suggests that chemical partitioning of PFAS between the different phases of sea ice also plays a role in their uptake during its formation. During sea ice melt, initial meltwater fractions were highly saline and predominantly contained short-chain PFAS, whereas the later, fresher meltwater fractions predominantly contained long-chain PFAS. Our results demonstrate that in highly saline parts of sea ice (near the upper and lower interfaces and in brine channels) significant chemical enrichment (ε) of PFAS can occur with concentrations in brine channels greatly exceeding those in seawater from which it forms (e.g., for PFOA, ε brine = 10 ± 4). This observation has implications for biological exposure to PFAS present in brine channels, a common feature of first-year sea ice which is the dominant ice type in a warming Arctic.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigating the Uptake and Fate of Poly- and Perfluoroalkylated Substances (PFAS) in Sea Ice Using an Experimental Sea Ice Chamber

Garnett

Halsall

Thomas

et al. 2021

Environ. Sci. Technol.

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“…Elevated concentrations of PFAAs in the uppermost ice layers of sea ice may be a result of entrainment of chemicals present in seawater during initial sea ice formation. 15 , 43 However, snow is also likely to play an important role in the delivery of PFAAs 44 to sea ice with the amount and timing of snowfall deposition likely to affect accumulation dynamics.…”

Section: Resultsmentioning

confidence: 99%

“… 10 , 15 Sea ice brine has also been shown to contain contaminant concentrations at levels significantly greater than those observed in the underlying seawater. 10 , 15 In the warming Arctic Ocean dominated by brine-rich single-season ice, this has important implications for contaminant exposure to the many organisms situated at the base of the pelagic food web, which are abundant in sea ice. Sympagic organisms, such as ice algae and associated heterotrophic protists and metazoans, inhabit a network of brine inclusions and brine channels at the base of the ice and may be particularly vulnerable to brine which is enriched in contaminants.…”

Section: Introductionmentioning

confidence: 99%

High Concentrations of Perfluoroalkyl Acids in Arctic Seawater Driven by Early Thawing Sea Ice

Garnett

Halsall

Vader³

et al. 2021

Environ. Sci. Technol.

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Poly- and perfluoroalkyl substances are synthetic chemicals that are widely present in the global environment including the Arctic. However, little is known about how these chemicals (particularly perfluoroalkyl acids, PFAA) enter the Arctic marine system and cycle between seawater and sea ice compartments. To evaluate this, we analyzed sea ice, snow, melt ponds, and near-surface seawater at two ice-covered stations located north of the Barents Sea (81 °N) with the aim of investigating PFAA dynamics in the late-season ice pack. Sea ice showed high concentrations of PFAA particularly at the surface with snow-ice (the uppermost sea ice layer strongly influenced by snow) comprising 26–62% of the total PFAA burden. Low salinities (<2.5 ppt) and low δ 18 O H20 values (<1‰ in snow and upper ice layers) in sea ice revealed the strong influence of meteoric water on sea ice, thus indicating a significant atmospheric source of PFAA with subsequent transfer down the sea ice column in meltwater. Importantly, the under-ice seawater (0.5 m depth) displayed some of the highest concentrations notably for the long-chain PFAA (e.g., PFOA 928 ± 617 pg L –1 ), which were ≈3-fold higher than those of deeper water (5 m depth) and ≈2-fold higher than those recently measured in surface waters of the North Sea infuenced by industrial inputs of PFAAs. The evidence provided here suggests that meltwater arising early in the melt season from snow and other surface ice floe components drives the higher PFAA concentrations observed in under-ice seawater, which could in turn influence the timing and extent of PFAA exposure for organisms at the base of the marine food web.

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“…We grew free-floating sea ice to (11.0 ± 0.9) cm (run 1) and (16.4 ± 2.7) cm (run 2) thickness (mean and standard deviation of measured ice core thickness). Measurements of sea-ice temperature, thickness, and the initial ocean salinity were used to force the model, which has been used previously to model experiments in the RvG-ASIC (Garnett et al, 2019;Thomas et al, 2020). We used the Griewank and Notz (2013) https://doi.org/10.5194/amt-2020-392 Preprint.…”

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confidence: 99%

The Roland von Glasow Air-Sea-Ice Chamber (RvG-ASIC): an experimental facility for studying ocean/sea-ice/atmosphere interactions

Thomas¹,

France²,

Crabeck³

et al. 2020

Preprint

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Abstract. Sea ice is difficult, expensive, and potentially dangerous to observe in nature. The remoteness of the Arctic and Southern Oceans complicates sampling logistics, while the heterogeneous nature of sea ice and rapidly changing environmental conditions present challenges for conducting process studies. Here, we describe the Roland von Glasow Air-Sea-Ice Chamber (RvG-ASIC), a laboratory facility designed to reproduce polar processes and overcome some of these challenges. The RvG-ASIC is an open-topped 3.5 m3 glass tank housed in a coldroom (temperature range: −55 to +30 °C). The RvG-ASIC is equipped with a wide suite of instruments for ocean, sea ice, and atmospheric measurements, as well as visible and UV lighting. The infrastructure, available instruments, and typical experimental protocols are described. To characterise some of the technical capabilities of our facility, we have quantified the timescale over which our chamber exchanges gas with the outside, τl = (0.66 ± 0.07) days, and the mixing rate of our experimental ocean, τm = (4.2 ± 0.1) minutes. Characterising our light field, we show that the light intensity across the tank varies by less than 10 % near the centre of the tank but drops to as low as 60 % of the maximum intensity in one corner. The temperature sensitivity of our light sources over the 400 nm to 700 nm range (PAR) is (0.028 ± 0.003) W m−2 °C−1, with a maximum irradiance of 26.4 W m−2 at 0 °C; over the 320 nm to 380 nm range, it is (0.16 ± 0.1) W m−2 °C−1, with a maximum irradiance of 5.6 W m−2 at 0 °C. We also present results characterising our experimental sea ice. The extinction coefficient for PAR varies from 3.7 m−1 to 6.1 m−1 when calculated from irradiance measurements exterior to the sea ice and from 4.5 m−1 to 6.2 m−1 when calculated from irradiance measurements within the sea ice. The bulk salinity of our experimental sea ice is measured using three techniques, modelled using a halo-dynamic one-dimensional (1D) gravity drainage model, and calculated from a salt and mass budget. The growth rate of our sea ice is between 2 cm d−1 and 4 cm d−1 for air temperatures of (−9.2 ± 0.9) °C and (−26.6 ± 0.9) °C. The PAR extinction coefficients, vertically integrated bulk salinities, and growth rates all lie within the range of previously reported comparable values for first-year sea ice. The vertically integrated bulk salinity and growth rates can be reproduced well by a 1D model. Taken together, the similarities between our laboratory sea ice and observations in nature, and our ability to reproduce our results with a model, give us confidence that sea ice grown in the RvG-ASIC is a good representation of natural sea ice.

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Mechanistic Insight into the Uptake and Fate of Persistent Organic Pollutants in Sea Ice

Cited by 23 publications

References 27 publications

Investigating the Uptake and Fate of Poly- and Perfluoroalkylated Substances (PFAS) in Sea Ice Using an Experimental Sea Ice Chamber

Investigating the Uptake and Fate of Poly- and Perfluoroalkylated Substances (PFAS) in Sea Ice Using an Experimental Sea Ice Chamber

High Concentrations of Perfluoroalkyl Acids in Arctic Seawater Driven by Early Thawing Sea Ice

The Roland von Glasow Air-Sea-Ice Chamber (RvG-ASIC): an experimental facility for studying ocean/sea-ice/atmosphere interactions

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