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<article language="en">
	<journal>
		<journal_title>Atmospheric Chemistry and Physics Discussions</journal_title>
		<journal_url>www.atmos-chem-phys-discuss.net</journal_url>
		<issn>1680-7367</issn>
		<eissn>1680-7375</eissn>
		<volume_number>9</volume_number>
		<issue_number>5</issue_number>
		<publication_year>2009</publication_year>
	</journal>
	<doi>10.5194/acpd-9-20913-2009</doi>
	<article_url>http://www.atmos-chem-phys-discuss.net/9/20913/2009/</article_url>
	<abstract_html>http://www.atmos-chem-phys-discuss.net/9/20913/2009/acpd-9-20913-2009.html</abstract_html>
	<fulltext_pdf>http://www.atmos-chem-phys-discuss.net/9/20913/2009/acpd-9-20913-2009.pdf</fulltext_pdf>
	<start_page>20913</start_page>
	<end_page>20948</end_page>
	<publication_date>2009-10-05</publication_date>
	<article_title content_type="html">Circumpolar measurements of speciated mercury, ozone and carbon monoxide in the boundary layer of the Arctic Ocean</article_title>
	<authors>
		<author numeration="1" affiliations="1">
			<name>J. Sommar</name>
			<email>jonas@mails.gyig.ac.cn</email>
		</author>
		<author numeration="2" affiliations="2">
			<name>M. E. Andersson</name>
		</author>
		<author numeration="3" affiliations="3,4">
			<name>H.-W. Jacobi</name>
		</author>
	</authors>
	<affiliations>
		<affiliation numeration="1" content_type="html">State key Laboratory of Environmental Geochemistry, Institute of  Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China</affiliation>
		<affiliation numeration="2" content_type="html">Department of Chemistry, Göteborg University, 41296 Göteborg, Sweden</affiliation>
		<affiliation numeration="3" content_type="html">Laboratoire de Glaciologie et Géophysique de l&apos;Environnement, CNRS –  Université Joseph Fourier Grenoble, 54 Rue Molière, 38400 St Martin d&apos;Hères, France</affiliation>
		<affiliation numeration="4" content_type="html">Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany</affiliation>
	</affiliations>
	<abstract content_type="html">Using the Swedish icebreaker Oden as a platform, continuous
measurements of airborne mercury (gaseous elemental mercury
(Hg&lt;sup&gt;0&lt;/sup&gt;), divalent mercury Hg&lt;sup&gt;II&lt;/sup&gt;(g) (acronym RGM) and
mercury attached to particles (PHg)) and some long-lived trace gases
(carbon monoxide CO and ozone O&lt;sub&gt;3&lt;/sub&gt;) were performed over the
North Atlantic and the Arctic Ocean. The measurements were performed
for nearly three months (July–September, 2005) during the Beringia
2005 expedition (from Göteborg, Sweden via the proper Northwest
Passage to the Beringia region Alaska – Chukchi Penninsula – Wrangel
Island and in-turn via a north-polar transect to Longyearbyen,
Spitsbergen). The Beringia 2005 expedition was the first time that
these species have been measured during summer over the Arctic Ocean
going from 60&amp;deg; to 90&amp;deg; N.
&lt;br&gt;&lt;br&gt;
During the North Atlantic transect, concentration levels of
Hg&lt;sup&gt;0&lt;/sup&gt;, CO and O&lt;sub&gt;3&lt;/sub&gt; were measured comparable to typical
levels for the ambient mid-hemispheric average. However, a rapid
increase of Hg&lt;sup&gt;0&lt;/sup&gt; in air and surface water was observed when
entering the ice-covered waters of the Canadian Arctic
archipelago. Large parts of the measured waters were supersaturated
with respect to Hg&lt;sup&gt;0&lt;/sup&gt;, reflecting a strong
disequilibrium. Heading through the sea ice of the Arctic Ocean,
a fraction of the strong Hg&lt;sup&gt;0&lt;/sup&gt;} pulse in the water was spilled
with some time-delay into the air samples collected
~20 m a.s.l. Several episodes of elevated
Hg&lt;sup&gt;0&lt;/sup&gt;(g) were encountered along the sea ice route with higher
mean concentration (1.81&amp;plusmn;0.43 ng m&lt;sup&gt;&amp;minus;3&lt;/sup&gt;) compared to
the marine boundary layer over ice-free oceanic waters
(1.55&amp;plusmn;0.21 ng m&lt;sup&gt;&amp;minus;3&lt;/sup&gt;). In addition, an overall majority
of the variance in the temporal series of Hg&lt;sup&gt;0&lt;/sup&gt; concentrations
was observed during July. Atmospheric boundary layer {O&lt;sub&gt;3&lt;/sub&gt;}
mixing ratios decreased when initially sailing northward. In the
Arctic, an O&lt;sub&gt;3&lt;/sub&gt; minimum around 15–20 ppbv was
observed during summer (July–August). Alongside the polar transect
during the beginning of autumn, a steady trend of increasing
O&lt;sub&gt;3&lt;/sub&gt; mixing ratios was measured returning to initial levels of
the expedition (&gt;30 ppbv). Ambient CO was fairly stable
(84&amp;plusmn12 ppbv) during the expedition. However, from the
Beaufort Sea and moving onwards steadily increasing CO mixing ratios
were observed (0.3 ppbv day&lt;sup&gt;&amp;minus;1&lt;/sup&gt;). On a comparison with
coeval archived CO and O&lt;sub&gt;3&lt;/sub&gt; data from the Arctic coastal strip
monitoring sites Barrow and Alert, the observations from Oden indicate
these species to be homogeneously distributed over the Arctic
Ocean. Neither correlated low ozone and GEM events nor elevated
concentrations of RGM and PHg were at any extent sampled, suggesting
that atmospheric mercury deposition to the Arctic basin is low during
the Polar summer and autumn. Elevated levels of Hg&lt;sup&gt;0&lt;/sup&gt; and CO
were episodically observed in air along the Chukchi Peninsula
indicating transport of regional pollution.</abstract>
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