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Atmospheric Transport and Deposition of Bromoanisoles Along a Temperate to Arctic Gradient Terry F. Bidleman, Eva Brorström-Lundén, Katarina Hansson, Hjalmar Laudon, Olle Nygren, and Mats Tysklind Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b03218 • Publication Date (Web): 08 Sep 2017 Downloaded from http://pubs.acs.org on September 10, 2017
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Environmental Science & Technology
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Atmospheric Transport and Deposition of Bromoanisoles
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Along a Temperate to Arctic Gradient
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Terry F. Bidleman1*, Eva Brorström-Lundén2, Katarina Hansson2, Hjalmar Laudon3,
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Olle Nygren4, Mats Tysklind1
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Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden; 2Swedish
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Environmental Research Institute (IVL), Aschebergsgatan 44, SE-411 33 Gothenburg, Sweden;
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Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
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(SLU), SE-901 83 Umeå, Sweden; 4Building Office, Umeå University, SE-901 87 Umeå,
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Sweden.
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*E-mail:
[email protected], phone (mobile): +46-72-510-1254
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Abstract Bromoanisoles (BAs) arise from O-methylation of bromophenols, produced by marine algae
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and invertebrates. BAs undergo sea-air exchange and are transported over the oceans. Here we
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report 2,4-DiBA and 2,4,6-TriBA in air and deposition on the Swedish west coast (Råö) and the
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interior of arctic Finland (Pallas). Results are discussed in perspective with previous
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measurements in the northern Baltic region in 2011-2013. BAs in air decreased from south to
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north in the order Råö ˃ northern Baltic ˃ Pallas. Geometric mean concentrations at Pallas
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increased significantly (p 2.5, we assumed PUF/air equilibrium and calculated the air concentration from:
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Equilibrium sampling: CA = KPA/CPUF
VS/VB > 2.5
(1)
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where CA and CPUF and KPA have units of pg m-3 air, pg g-1 PUF and m3 g-1, respectively.
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When VS/VB ≤ 2.5, the breakthrough level b was estimated as described in Supporting
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Information and the air concentration was calculated from the mass of analyte collected by the
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PUF (QPUF), the sampled air volume VS and 1-b:
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Non-equilibrium sampling: CA = QPUF/[VS*(1-b)]
VS/VB ≤ 2.5
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(2)
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Environmental Science & Technology
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Most Råö samples were collected under equilibrium conditions, due to the high air volumes and
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relatively warm temperatures (Table S1). A few non-equilibrium events occurred in winter-early
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spring. The frequency of these was greater at Pallas and only summer samples were collected
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under equilibrium conditions (Table S2).
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3. Results and Discussion
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3.1. Atmospheric concentrations
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BAs were above the LOD in every sample analyzed. Mean and geometric mean (GM)
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concentrations of 2,4-DiBA and 2,4,6-TriBA in air at Råö and Pallas are summarized in Table 1
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and details for each sample are given in Tables S1 and S2. Discontinuities in the biweekly or
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monthly records are due to missing samples. We also identified 2,6-DiBA at about 10% of 2,4-
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DiBA concentrations, but quantitative results are not reported. 2,6-DiBA is more volatile than the
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other DiBAs56 and its KPA has not been determined. Searches for 2,5- and 3,5-DiBA were
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negative, as in our previous Baltic study.43
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Temporal trends of BAs at Råö and Pallas during each year of observation are shown in
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Figures S2 and S3. Annual mean concentrations at Råö ranged from 20 ± 9.1 to 41 ± 20 pg m-3
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for 2,4-DiBA, and 43 ± 20 to 74 ± 36 pg m-3 for 2,4,6-TriBA. Annual means at Pallas ranged
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from 3.7 ± 4.4 to 20 ± 23 pg m-3 for 2,4-DiBA and 4.9 ± 5.5 to 14 ± 12 pg m-3 for 2,4,6-TriBA.
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GM concentrations of 2,4-DiBA and increased significantly at Pallas between 2002-2015 (p =
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0.041), while an increasing trend was also suggested for 2,4,6-TriBA, but was not significant (p =
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0.064).
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The trends in Figures S2 and S3 are summarized in Figure 3a, derived as follows. Monthly
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concentrations in each year (5 years at Råö, 7 years at Pallas) were expressed as percentages of
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the peak month concentrations and these percentages were averaged over the years.
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Concentrations of both BAs at Råö rose smoothly from spring to midsummer and remained near
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peak until December, when they dropped sharply and remained low until March. Mean trends 7 ACS Paragon Plus Environment
Environmental Science & Technology
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were different at Pallas. BA concentrations rose from May, peaked in September, and remained
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high through December for 2,4,6-TriBA while dropping for 2,4-DiBA. Lowest concentrations for
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both BAs occurred in March-April. Proportions of the two BAs (Figure 3b) are discussed in
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Section 3.3.
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BAs in air were previously measured by deploying passive samplers over 3-4 months at
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northern Baltic island stations Holmön (HOL, 63.79 oN, 20.84 oE ) and Haparanda Sandskär
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(SKR, 65.57 oN, 23.75 oE) and at Krycklan Catchment (KRY, 64.23 oN, 19.77 oE), about 60 km
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inland, and active air samples were also collected during short-term campaigns on HOL.51 Mean
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concentrations of 2,4-DiBA and 2,4,6-TriBA were 23 ± 16 and 43 ± 30 pg m-3 at HOL, 19 ± 13
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and 18 ± 7.9 pg m-3 at SKR, and 38 ± 19 and 23 ± 8.9 pg m-3 at KRY (Table 1). Mean ± SD
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concentrations at the five sites between 2012-2015 are summarized in Figure 2 and show a
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general decrease northward with Råö > HOL ≈ KRY > SKR > Pallas. Others have reported BAs
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in air along the Norwegian coast. Concentrations in air at Lista (58.10 oN, 6.57 oE) in 2003 were
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19 ± 12 pg m-3 for 2,4-DiBA and 13 ± 9 pg m-3 for 2,4,6-TriBA.49 2,4,6-TriBA was measured at
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Birkenes (58.38 oN, 8.25 oE) from 2007-2014 (3.3 – 5.0 pg m-3) and Andøya (69.28 °N, 16.01
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°E) from 2010-2014 (2.8 – 5.7 pg m-3).38,39 Levels over the North and South Atlantic in 1993 and
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1999-2000 ranged from 0.2 – 7 pg m-3 for 2,4-DiBA, 0.4 – 3.6 pg m-3 for 2,6-DiBA and 0.5 – 42
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pg m-3 for 2,4,6-TriBA .4,45,46 Means over the Canadian Arctic Archipelago in 2007-2008 were 15
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± 10 pg m-3 for 2,4-DiBA and 20 ± 14 pg m-3 for 2,4,6-TriBA.48
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Temperature relationships are examined for plotting the logarithm of partial pressure (log
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P/Pa) versus 1/T (K). Regressions at Råö are significant for each year (p
