Pan-European rural monitoring network shows dominance of NH<sub>3</sub> gas and NH<sub>4</sub>NO<sub>3</sub> aerosol in inorganic atmospheric pollution load
<p>A comprehensive European dataset on monthly atmospheric NH<span class="inline-formula"><sub>3</sub></span>, acid gases (HNO<span class="inline-formula"><sub>3</sub></span>, SO<span class="inline-formula"><...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/21/875/2021/acp-21-875-2021.pdf |
| _version_ | 1830483678550032384 |
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| author | Y. S. Tang C. R. Flechard U. Dämmgen S. Vidic V. Djuricic M. Mitosinkova H. T. Uggerud M. J. Sanz M. J. Sanz M. J. Sanz I. Simmons U. Dragosits E. Nemitz M. Twigg N. van Dijk Y. Fauvel F. Sanz M. Ferm C. Perrino M. Catrambone D. Leaver C. F. Braban J. N. Cape M. R. Heal M. A. Sutton |
| author_facet | Y. S. Tang C. R. Flechard U. Dämmgen S. Vidic V. Djuricic M. Mitosinkova H. T. Uggerud M. J. Sanz M. J. Sanz M. J. Sanz I. Simmons U. Dragosits E. Nemitz M. Twigg N. van Dijk Y. Fauvel F. Sanz M. Ferm C. Perrino M. Catrambone D. Leaver C. F. Braban J. N. Cape M. R. Heal M. A. Sutton |
| author_sort | Y. S. Tang |
| collection | DOAJ |
| description | <p>A comprehensive European dataset on monthly atmospheric NH<span class="inline-formula"><sub>3</sub></span>, acid gases
(HNO<span class="inline-formula"><sub>3</sub></span>, SO<span class="inline-formula"><sub>2</sub></span>, HCl), and aerosols (NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="a9b2fdba183dceff94210c316afa95ef"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00001.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00001.png"/></svg:svg></span></span>, NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="1933cd4f78557ae19e1c84fa4d0b5473"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00002.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00002.png"/></svg:svg></span></span>,
SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="6051c44ba131ac206db43e824688e92d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00003.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00003.png"/></svg:svg></span></span>, Cl<span class="inline-formula"><sup>−</sup></span>, Na<span class="inline-formula"><sup>+</sup></span>, Ca<span class="inline-formula"><sup>2+</sup></span>, Mg<span class="inline-formula"><sup>2+</sup>)</span> is presented and
analysed. Speciated measurements were made with a low-volume denuder and
filter pack method (DEnuder for Long-Term Atmospheric sampling, DELTA<sup>®</sup>) as part of the EU
NitroEurope (NEU) integrated project. Altogether, there were 64 sites in 20
countries (2006–2010), coordinated between seven European laboratories. Bulk wet-deposition measurements were carried out at 16 co-located sites (2008–2010).
Inter-comparisons of chemical analysis and DELTA<sup>®</sup>
measurements allowed an assessment of comparability between laboratories.</p>
<p><span id="page876"/>The form and concentrations of the different gas and aerosol components
measured varied between individual sites and grouped sites according to
country, European regions, and four main ecosystem types (crops, grassland,
forests, and semi-natural). The smallest concentrations (with the exception of
SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="9def59c1763723bf85d4c029a1ebd14e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00004.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00004.png"/></svg:svg></span></span> and Na<span class="inline-formula"><sup>+</sup></span>) were in northern Europe (Scandinavia), with
broad elevations of all components across other regions. SO<span class="inline-formula"><sub>2</sub></span>
concentrations were highest in central and eastern Europe, with larger
SO<span class="inline-formula"><sub>2</sub></span> emissions, but particulate SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="49798bc14746e7788afe38c7f4bc425f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00005.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00005.png"/></svg:svg></span></span> concentrations were more
homogeneous between regions. Gas-phase NH<span class="inline-formula"><sub>3</sub></span> was the most abundant single
measured component at the majority of sites, with the largest variability in
concentrations across the network. The largest concentrations of NH<span class="inline-formula"><sub>3</sub></span>,
NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M22" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="51ca01690260423140b5b0de9583232a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00006.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00006.png"/></svg:svg></span></span>, and NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="d4917cb251612ae03efebb0a66479930"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00007.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00007.png"/></svg:svg></span></span> were at cropland sites in intensively
managed agricultural areas (e.g. Borgo Cioffi in Italy), and the smallest were at
remote semi-natural and forest sites (e.g. Lompolojänkkä, Finland),
highlighting the potential for NH<span class="inline-formula"><sub>3</sub></span> to drive the formation of both
NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M25" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="97d6670f25963670a5296db4fdcc740f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00008.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00008.png"/></svg:svg></span></span> and NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M26" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="d96e0e0e6a6172a7d34ac185b1d0a8a7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00009.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00009.png"/></svg:svg></span></span> aerosol. In the aerosol phase,
NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M27" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="85fd114689db246c4a85801ec5a5cef2"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00010.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00010.png"/></svg:svg></span></span> was highly correlated with both NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M28" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a1391ede9a489b3338de96b652340830"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00011.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00011.png"/></svg:svg></span></span> and
SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M29" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="29af680a2c2c3e13b3242191be5b1002"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00012.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00012.png"/></svg:svg></span></span>, with a near-<span class="inline-formula">1:1</span> relationship between the equivalent
concentrations of NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M31" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="c1c3b9106f16e5133fc0596b88c825a9"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00013.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00013.png"/></svg:svg></span></span> and sum (NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M32" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup><mo>+</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="16pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="ddbe66d730701bfadefff5769c4fc105"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00014.svg" width="16pt" height="16pt" src="acp-21-875-2021-ie00014.png"/></svg:svg></span></span>
SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M33" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup><mo>)</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="16pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="ce48dadc7f162bbff7d21af668787813"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00015.svg" width="16pt" height="17pt" src="acp-21-875-2021-ie00015.png"/></svg:svg></span></span>, of which around 60 % was as NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span>.</p>
<p>Distinct seasonality was also observed in the data, influenced by changes
in emissions, chemical interactions, and the influence of meteorology on
partitioning between the main inorganic gases and aerosol species.
Springtime maxima in NH<span class="inline-formula"><sub>3</sub></span> were attributed to the main period of manure
spreading, while the peak in summer and trough in winter were linked to the
influence of temperature and rainfall on emissions, deposition, and
gas–aerosol-phase equilibrium. Seasonality in SO<span class="inline-formula"><sub>2</sub></span> was mainly driven by
emissions (combustion), with concentrations peaking in winter, except in
southern Europe, where the peak occurred in summer. Particulate
SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M38" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="af927745ea04007aff9f618f883ce002"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00016.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00016.png"/></svg:svg></span></span> showed large peaks in concentrations in summer in southern
and eastern Europe, contrasting with much smaller peaks occurring in early
spring in other regions. The peaks in particulate SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M39" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="43551dd6939ff027a946c13e8be02135"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00017.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00017.png"/></svg:svg></span></span> coincided
with peaks in NH<span class="inline-formula"><sub>3</sub></span> concentrations, attributed to the formation of the
stable (NH<span class="inline-formula"><sub>4</sub>)<sub>2</sub></span>SO<span class="inline-formula"><sub>4</sub></span>. HNO<span class="inline-formula"><sub>3</sub></span> concentrations were more complex,
related to traffic and industrial emissions, photochemistry, and
HNO<span class="inline-formula"><sub>3</sub></span>:NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> partitioning. While HNO<span class="inline-formula"><sub>3</sub></span> concentrations were
seen to peak in the summer in eastern and southern Europe (increased
photochemistry), the absence of a spring peak in HNO<span class="inline-formula"><sub>3</sub></span> in all regions
may be explained by the depletion of HNO<span class="inline-formula"><sub>3</sub></span> through reaction with surplus
NH<span class="inline-formula"><sub>3</sub></span> to form the semi-volatile aerosol NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span>. Cooler, wetter
conditions in early spring favour the formation and persistence of
NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> in the aerosol phase, consistent with the higher springtime
concentrations of NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M55" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="b2f4688389b28d9f41ec2e2928fae4e0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00018.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00018.png"/></svg:svg></span></span> and NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M56" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="3a8cc437bdf71dca45b98349c6558e05"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00019.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00019.png"/></svg:svg></span></span>. The seasonal profile of
NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M57" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a402a240ce5132e2a27ae10dba777396"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00020.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00020.png"/></svg:svg></span></span> was mirrored by NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M58" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="86d32ea7a5702b11ca110db304544d0d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00021.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00021.png"/></svg:svg></span></span>, illustrating the influence of
gas–aerosol partitioning of NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> in the seasonality of these
components.</p>
<p>Gas-phase NH<span class="inline-formula"><sub>3</sub></span> and aerosol NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> were the dominant species in
the total inorganic gas and aerosol species measured in the NEU network.
With the current and projected trends in SO<span class="inline-formula"><sub>2</sub></span>, NO<span class="inline-formula"><sub><i>x</i></sub></span>, and NH<span class="inline-formula"><sub>3</sub></span>
emissions, concentrations of NH<span class="inline-formula"><sub>3</sub></span> and NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> can be expected
to continue to dominate the inorganic pollution load over the next decades,
especially NH<span class="inline-formula"><sub>3</sub></span>, which is linked to substantial exceedances of
ecological thresholds across Europe. The shift from (NH<span class="inline-formula"><sub>4</sub>)<sub>2</sub></span>SO<span class="inline-formula"><sub>4</sub></span>
to an atmosphere more abundant in NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> is expected to maintain a
larger fraction of reactive N in the gas phase by partitioning to NH<span class="inline-formula"><sub>3</sub></span>
and HNO<span class="inline-formula"><sub>3</sub></span> in warm weather, while NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> continues to
contribute to exceedances of air quality limits for PM<span class="inline-formula"><sub>2.5</sub></span>.</p> |
| first_indexed | 2024-12-21T17:56:26Z |
| format | Article |
| id | doaj.art-a952b0c04758491b864445c08bba8669 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-21T17:56:26Z |
| publishDate | 2021-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-a952b0c04758491b864445c08bba86692022-12-21T18:55:12ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242021-01-012187591410.5194/acp-21-875-2021Pan-European rural monitoring network shows dominance of NH<sub>3</sub> gas and NH<sub>4</sub>NO<sub>3</sub> aerosol in inorganic atmospheric pollution loadY. S. Tang0C. R. Flechard1U. Dämmgen2S. Vidic3V. Djuricic4M. Mitosinkova5H. T. Uggerud6M. J. Sanz7M. J. Sanz8M. J. Sanz9I. Simmons10U. Dragosits11E. Nemitz12M. Twigg13N. van Dijk14Y. Fauvel15F. Sanz16M. Ferm17C. Perrino18M. Catrambone19D. Leaver20C. F. Braban21J. N. Cape22M. R. Heal23M. A. Sutton24UK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UKFrench National Research Institute for Agriculture, Food and Environment (INRAE), UMR 1069 SAS, 65 rue de St-Brieuc, 35042 Rennes CEDEX, Francevon Thunen Institut (vTI), Bundesallee 50, 38116 Braunschweig, GermanyMeteorological and Hydrological Service of Croatia (MHSC), Research and Development Division, Gric 3, 10000 Zagreb, CroatiaMeteorological and Hydrological Service of Croatia (MHSC), Research and Development Division, Gric 3, 10000 Zagreb, CroatiaSlovak Hydrometeorological Institute (SHMU), Department of Air Quality, Jeseniova 17, 833 15 Bratislava, Slovak RepublicNorwegian Institute for Air Research (NILU), P.O. Box 100, 2027 Kjeller, NorwayFundación CEAM, C/Charles R. Darwin, 46980 Paterna (Valencia), SpainBasque Centre for Climate Change, Sede Building 1, Scientific Campus of the University of the Basque Country, 48940, Leioa, Bizkaia, SpainIkerbasque, Basque Science Foundation, María Díaz Haroko Kalea, 3, 48013 Bilbo, Bizkaia, SpainUK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UKUK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UKUK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UKUK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UKUK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UKFrench National Research Institute for Agriculture, Food and Environment (INRAE), UMR 1069 SAS, 65 rue de St-Brieuc, 35042 Rennes CEDEX, FranceFundación CEAM, C/Charles R. Darwin, 46980 Paterna (Valencia), SpainIVL Swedish Environmental Research Institute, P.O. Box 5302, 400 14, Gothenburg, SwedenC.N.R. Institute of Atmospheric Pollution Research, via Salaria Km. 29, 300 – 00015, Monterotondo st, Rome, ItalyC.N.R. Institute of Atmospheric Pollution Research, via Salaria Km. 29, 300 – 00015, Monterotondo st, Rome, ItalyUK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UKUK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UKUK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UKSchool of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, UKUK Centre for Ecology & Hydrology (UKCEH), Bush Estate, Penicuik, Midlothian EH26 0QB, UK<p>A comprehensive European dataset on monthly atmospheric NH<span class="inline-formula"><sub>3</sub></span>, acid gases (HNO<span class="inline-formula"><sub>3</sub></span>, SO<span class="inline-formula"><sub>2</sub></span>, HCl), and aerosols (NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="a9b2fdba183dceff94210c316afa95ef"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00001.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00001.png"/></svg:svg></span></span>, NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="1933cd4f78557ae19e1c84fa4d0b5473"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00002.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00002.png"/></svg:svg></span></span>, SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="6051c44ba131ac206db43e824688e92d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00003.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00003.png"/></svg:svg></span></span>, Cl<span class="inline-formula"><sup>−</sup></span>, Na<span class="inline-formula"><sup>+</sup></span>, Ca<span class="inline-formula"><sup>2+</sup></span>, Mg<span class="inline-formula"><sup>2+</sup>)</span> is presented and analysed. Speciated measurements were made with a low-volume denuder and filter pack method (DEnuder for Long-Term Atmospheric sampling, DELTA<sup>®</sup>) as part of the EU NitroEurope (NEU) integrated project. Altogether, there were 64 sites in 20 countries (2006–2010), coordinated between seven European laboratories. Bulk wet-deposition measurements were carried out at 16 co-located sites (2008–2010). Inter-comparisons of chemical analysis and DELTA<sup>®</sup> measurements allowed an assessment of comparability between laboratories.</p> <p><span id="page876"/>The form and concentrations of the different gas and aerosol components measured varied between individual sites and grouped sites according to country, European regions, and four main ecosystem types (crops, grassland, forests, and semi-natural). The smallest concentrations (with the exception of SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="9def59c1763723bf85d4c029a1ebd14e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00004.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00004.png"/></svg:svg></span></span> and Na<span class="inline-formula"><sup>+</sup></span>) were in northern Europe (Scandinavia), with broad elevations of all components across other regions. SO<span class="inline-formula"><sub>2</sub></span> concentrations were highest in central and eastern Europe, with larger SO<span class="inline-formula"><sub>2</sub></span> emissions, but particulate SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="49798bc14746e7788afe38c7f4bc425f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00005.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00005.png"/></svg:svg></span></span> concentrations were more homogeneous between regions. Gas-phase NH<span class="inline-formula"><sub>3</sub></span> was the most abundant single measured component at the majority of sites, with the largest variability in concentrations across the network. The largest concentrations of NH<span class="inline-formula"><sub>3</sub></span>, NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M22" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="51ca01690260423140b5b0de9583232a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00006.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00006.png"/></svg:svg></span></span>, and NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="d4917cb251612ae03efebb0a66479930"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00007.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00007.png"/></svg:svg></span></span> were at cropland sites in intensively managed agricultural areas (e.g. Borgo Cioffi in Italy), and the smallest were at remote semi-natural and forest sites (e.g. Lompolojänkkä, Finland), highlighting the potential for NH<span class="inline-formula"><sub>3</sub></span> to drive the formation of both NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M25" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="97d6670f25963670a5296db4fdcc740f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00008.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00008.png"/></svg:svg></span></span> and NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M26" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="d96e0e0e6a6172a7d34ac185b1d0a8a7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00009.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00009.png"/></svg:svg></span></span> aerosol. In the aerosol phase, NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M27" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="85fd114689db246c4a85801ec5a5cef2"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00010.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00010.png"/></svg:svg></span></span> was highly correlated with both NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M28" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a1391ede9a489b3338de96b652340830"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00011.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00011.png"/></svg:svg></span></span> and SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M29" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="29af680a2c2c3e13b3242191be5b1002"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00012.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00012.png"/></svg:svg></span></span>, with a near-<span class="inline-formula">1:1</span> relationship between the equivalent concentrations of NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M31" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="c1c3b9106f16e5133fc0596b88c825a9"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00013.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00013.png"/></svg:svg></span></span> and sum (NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M32" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup><mo>+</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="16pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="ddbe66d730701bfadefff5769c4fc105"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00014.svg" width="16pt" height="16pt" src="acp-21-875-2021-ie00014.png"/></svg:svg></span></span> SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M33" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup><mo>)</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="16pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="ce48dadc7f162bbff7d21af668787813"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00015.svg" width="16pt" height="17pt" src="acp-21-875-2021-ie00015.png"/></svg:svg></span></span>, of which around 60 % was as NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span>.</p> <p>Distinct seasonality was also observed in the data, influenced by changes in emissions, chemical interactions, and the influence of meteorology on partitioning between the main inorganic gases and aerosol species. Springtime maxima in NH<span class="inline-formula"><sub>3</sub></span> were attributed to the main period of manure spreading, while the peak in summer and trough in winter were linked to the influence of temperature and rainfall on emissions, deposition, and gas–aerosol-phase equilibrium. Seasonality in SO<span class="inline-formula"><sub>2</sub></span> was mainly driven by emissions (combustion), with concentrations peaking in winter, except in southern Europe, where the peak occurred in summer. Particulate SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M38" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="af927745ea04007aff9f618f883ce002"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00016.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00016.png"/></svg:svg></span></span> showed large peaks in concentrations in summer in southern and eastern Europe, contrasting with much smaller peaks occurring in early spring in other regions. The peaks in particulate SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M39" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="43551dd6939ff027a946c13e8be02135"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00017.svg" width="13pt" height="17pt" src="acp-21-875-2021-ie00017.png"/></svg:svg></span></span> coincided with peaks in NH<span class="inline-formula"><sub>3</sub></span> concentrations, attributed to the formation of the stable (NH<span class="inline-formula"><sub>4</sub>)<sub>2</sub></span>SO<span class="inline-formula"><sub>4</sub></span>. HNO<span class="inline-formula"><sub>3</sub></span> concentrations were more complex, related to traffic and industrial emissions, photochemistry, and HNO<span class="inline-formula"><sub>3</sub></span>:NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> partitioning. While HNO<span class="inline-formula"><sub>3</sub></span> concentrations were seen to peak in the summer in eastern and southern Europe (increased photochemistry), the absence of a spring peak in HNO<span class="inline-formula"><sub>3</sub></span> in all regions may be explained by the depletion of HNO<span class="inline-formula"><sub>3</sub></span> through reaction with surplus NH<span class="inline-formula"><sub>3</sub></span> to form the semi-volatile aerosol NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span>. Cooler, wetter conditions in early spring favour the formation and persistence of NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> in the aerosol phase, consistent with the higher springtime concentrations of NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M55" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="b2f4688389b28d9f41ec2e2928fae4e0"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00018.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00018.png"/></svg:svg></span></span> and NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M56" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="3a8cc437bdf71dca45b98349c6558e05"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00019.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00019.png"/></svg:svg></span></span>. The seasonal profile of NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M57" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a402a240ce5132e2a27ae10dba777396"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00020.svg" width="9pt" height="16pt" src="acp-21-875-2021-ie00020.png"/></svg:svg></span></span> was mirrored by NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M58" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="86d32ea7a5702b11ca110db304544d0d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-875-2021-ie00021.svg" width="8pt" height="15pt" src="acp-21-875-2021-ie00021.png"/></svg:svg></span></span>, illustrating the influence of gas–aerosol partitioning of NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> in the seasonality of these components.</p> <p>Gas-phase NH<span class="inline-formula"><sub>3</sub></span> and aerosol NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> were the dominant species in the total inorganic gas and aerosol species measured in the NEU network. With the current and projected trends in SO<span class="inline-formula"><sub>2</sub></span>, NO<span class="inline-formula"><sub><i>x</i></sub></span>, and NH<span class="inline-formula"><sub>3</sub></span> emissions, concentrations of NH<span class="inline-formula"><sub>3</sub></span> and NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> can be expected to continue to dominate the inorganic pollution load over the next decades, especially NH<span class="inline-formula"><sub>3</sub></span>, which is linked to substantial exceedances of ecological thresholds across Europe. The shift from (NH<span class="inline-formula"><sub>4</sub>)<sub>2</sub></span>SO<span class="inline-formula"><sub>4</sub></span> to an atmosphere more abundant in NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> is expected to maintain a larger fraction of reactive N in the gas phase by partitioning to NH<span class="inline-formula"><sub>3</sub></span> and HNO<span class="inline-formula"><sub>3</sub></span> in warm weather, while NH<span class="inline-formula"><sub>4</sub></span>NO<span class="inline-formula"><sub>3</sub></span> continues to contribute to exceedances of air quality limits for PM<span class="inline-formula"><sub>2.5</sub></span>.</p>https://acp.copernicus.org/articles/21/875/2021/acp-21-875-2021.pdf |
| spellingShingle | Y. S. Tang C. R. Flechard U. Dämmgen S. Vidic V. Djuricic M. Mitosinkova H. T. Uggerud M. J. Sanz M. J. Sanz M. J. Sanz I. Simmons U. Dragosits E. Nemitz M. Twigg N. van Dijk Y. Fauvel F. Sanz M. Ferm C. Perrino M. Catrambone D. Leaver C. F. Braban J. N. Cape M. R. Heal M. A. Sutton Pan-European rural monitoring network shows dominance of NH<sub>3</sub> gas and NH<sub>4</sub>NO<sub>3</sub> aerosol in inorganic atmospheric pollution load Atmospheric Chemistry and Physics |
| title | Pan-European rural monitoring network shows dominance of NH<sub>3</sub> gas and NH<sub>4</sub>NO<sub>3</sub> aerosol in inorganic atmospheric pollution load |
| title_full | Pan-European rural monitoring network shows dominance of NH<sub>3</sub> gas and NH<sub>4</sub>NO<sub>3</sub> aerosol in inorganic atmospheric pollution load |
| title_fullStr | Pan-European rural monitoring network shows dominance of NH<sub>3</sub> gas and NH<sub>4</sub>NO<sub>3</sub> aerosol in inorganic atmospheric pollution load |
| title_full_unstemmed | Pan-European rural monitoring network shows dominance of NH<sub>3</sub> gas and NH<sub>4</sub>NO<sub>3</sub> aerosol in inorganic atmospheric pollution load |
| title_short | Pan-European rural monitoring network shows dominance of NH<sub>3</sub> gas and NH<sub>4</sub>NO<sub>3</sub> aerosol in inorganic atmospheric pollution load |
| title_sort | pan european rural monitoring network shows dominance of nh sub 3 sub gas and nh sub 4 sub no sub 3 sub aerosol in inorganic atmospheric pollution load |
| url | https://acp.copernicus.org/articles/21/875/2021/acp-21-875-2021.pdf |
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