scholarly journals Iodine-mediated coastal particle formation: an overview of the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) Roscoff coastal study

2009 ◽  
Vol 9 (6) ◽  
pp. 26421-26489 ◽  
Author(s):  
G. McFiggans ◽  
C. S. E. Bale ◽  
S. M. Ball ◽  
J. M. Beames ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ultrafine Particles ◽  
Marine Boundary Layer ◽  
Cloud Condensation Nuclei ◽  
Measurement Techniques ◽  
Ultrafine Particle ◽  
Molecular Iodine ◽  
Particle Formation ◽  
North West ◽  
Iodine Species

Abstract. This paper presents a summary of the measurements that were made during the heavily-instrumented Reactive Halogens in the Marine Boundary Layer (RHaMBLe) coastal study in Roscoff on the North West coast of France. It was clearly demonstrated that iodine-mediated coastal particle formation occurs, driven by daytime low tide emission of molecular iodine, I2, by macroalgal species fully or partially exposed by the receding waterline. Ultrafine particle concentrations strongly correlate with the rapidly recycled reactive iodine species, IO, produced at high concentrations following photolysis of I2. The heterogeneous macroalgal I2 sources lead to variable relative concentrations of iodine species observed by path-integrated and in situ measurement techniques. Apparent particle emission fluxes were associated with an enhanced apparent depositional flux of ozone, consistent with both a direct O3 deposition to macroalgae and involvement of O3 in iodine photochemistry and subsequent particle formation below the measurement height. The magnitude of the particle formation events was observed to be greatest at the lowest tides with higher concentrations of ultrafine particles growing to much larger sizes, probably by the condensation of anthropogenically-formed condensable material. At such sizes the particles should be able to act as cloud condensation nuclei at reasonable atmospheric supersaturations.

scholarly journals Iodine-mediated coastal particle formation: an overview of the Reactive Halogens in the Marine Boundary Layer (RHaMBLe) Roscoff coastal study

2010 ◽  
Vol 10 (6) ◽  
pp. 2975-2999 ◽  
Author(s):  
G. McFiggans ◽  
C. S. E. Bale ◽  
S. M. Ball ◽  
J. M. Beames ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ultrafine Particles ◽  
Marine Boundary Layer ◽  
Cloud Condensation Nuclei ◽  
Measurement Techniques ◽  
Ultrafine Particle ◽  
Molecular Iodine ◽  
Particle Formation ◽  
North West ◽  
Iodine Species

Abstract. This paper presents a summary of the measurements made during the heavily-instrumented Reactive Halogens in the Marine Boundary Layer (RHaMBLe) coastal study in Roscoff on the North West coast of France throughout September 2006. It was clearly demonstrated that iodine-mediated coastal particle formation occurs, driven by daytime low tide emission of molecular iodine, I2, by macroalgal species fully or partially exposed by the receding waterline. Ultrafine particle concentrations strongly correlate with the rapidly recycled reactive iodine species, IO, produced at high concentrations following photolysis of I2. The heterogeneous macroalgal I2 sources lead to variable relative concentrations of iodine species observed by path-integrated and in situ measurement techniques. Apparent particle emission fluxes were associated with an enhanced apparent depositional flux of ozone, consistent with both a direct O3 deposition to macroalgae and involvement of O3 in iodine photochemistry and subsequent particle formation below the measurement height. The magnitude of the particle formation events was observed to be greatest at the lowest tides with the highest concentrations of ultrafine particles growing to the largest sizes, probably by the condensation of anthropogenically-formed condensable material. At such sizes the particles should be able to act as cloud condensation nuclei at reasonable atmospheric supersaturations.

scholarly journals Summertime observations of elevated levels of ultrafine particles in the high Arctic marine boundary layer

2017 ◽  
Vol 17 (8) ◽  
pp. 5515-5535 ◽  
Author(s):  
Julia Burkart ◽  
Megan D. Willis ◽  
Heiko Bozem ◽  
Jennie L. Thomas ◽  
Kathy Law ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ultrafine Particles ◽  
Marine Boundary Layer ◽  
Ultrafine Particle ◽  
High Arctic ◽  
Particle Formation ◽  
Open Ocean ◽  
Biologically Active ◽  
The Arctic ◽  
Depositional Processes

Abstract. Motivated by increasing levels of open ocean in the Arctic summer and the lack of prior altitude-resolved studies, extensive aerosol measurements were made during 11 flights of the NETCARE July 2014 airborne campaign from Resolute Bay, Nunavut. Flights included vertical profiles (60 to 3000 m above ground level) over open ocean, fast ice, and boundary layer clouds and fogs. A general conclusion, from observations of particle numbers between 5 and 20 nm in diameter (N5 − 20), is that ultrafine particle formation occurs readily in the Canadian high Arctic marine boundary layer, especially just above ocean and clouds, reaching values of a few thousand particles cm−3. By contrast, ultrafine particle concentrations are much lower in the free troposphere. Elevated levels of larger particles (for example, from 20 to 40 nm in size, N20 − 40) are sometimes associated with high N5 − 20, especially over low clouds, suggestive of aerosol growth. The number densities of particles greater than 40 nm in diameter (N >  40) are relatively depleted at the lowest altitudes, indicative of depositional processes that will lower the condensation sink and promote new particle formation. The number of cloud condensation nuclei (CCN; measured at 0.6 % supersaturation) are positively correlated with the numbers of small particles (down to roughly 30 nm), indicating that some fraction of these newly formed particles are capable of being involved in cloud activation. Given that the summertime marine Arctic is a biologically active region, it is important to better establish the links between emissions from the ocean and the formation and growth of ultrafine particles within this rapidly changing environment.

scholarly journals Direct evidence for coastal iodine particles from Laminaria macroalgae – linkage to emissions of molecular iodine

2004 ◽  
Vol 4 (3) ◽  
pp. 701-713 ◽  
Author(s):  
G. McFiggans ◽  
H. Coe ◽  
R. Burgess ◽  
J. Allan ◽  
M. Cubison ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Forcing ◽  
Particle Production ◽  
Marine Boundary Layer ◽  
Cloud Condensation Nuclei ◽  
Ultrafine Particle ◽  
Molecular Iodine ◽  
Photo Oxidation ◽  
Coastal Boundary Layer ◽  
Coastal Boundary

Abstract. Renewal of ultrafine aerosols in the marine boundary layer may lead to repopulation of the marine distribution and ultimately determine the concentration of cloud condensation nuclei (CCN). Thus the formation of nanometre-scale particles can lead to enhanced scattering of incoming radiation and a net cooling of the atmosphere. The recent demonstration of the chamber formation of new particles from the photolytic production of condensable iodine-containing compounds from diiodomethane (CH2I2), (O'Dowd et al., 2002; Kolb, 2002; Jimenez et al., 2003a; Burkholder and Ravishankara, 2003), provides an additional mechanism to the gas-to-particle conversion of sulphuric acid formed in the photo-oxidation of dimethylsulphide for marine aerosol repopulation. CH2I2 is emitted from seaweeds (Carpenter et al., 1999, 2000) and has been suggested as an initiator of particle formation. We demonstrate here for the first time that ultrafine iodine-containing particles are produced by intertidal macroalgae exposed to ambient levels of ozone. The particle composition is very similar both to those formed in the chamber photo-oxidation of diiodomethane and in the oxidation of molecular iodine by ozone. The particles formed in all three systems are similarly aspherical. When small, those formed in the molecular iodine system swell only moderately when exposed to increased humidity environments, and swell progressively less with increasing size; this behaviour occurs whether they are formed in dry or humid environments, in contrast to those in the CH2I2 system. Direct coastal boundary layer observations of molecular iodine, ultrafine particle production and iodocarbons are reported. Using a newly measured molecular iodine photolysis rate, it is shown that, if atomic iodine is involved in the observed particle bursts, it is of the order of at least 1000 times more likely to result from molecular iodine photolysis than diiodomethane photolysis. A hypothesis for molecular iodine release from intertidal macroalgae is presented and the potential importance of macroalgal iodine particles in their contribution to CCN and global radiative forcing are discussed.

scholarly journals Direct evidence for coastal iodine particles from <i>Laminaria</i> macroalgae – linkage to emissions of molecular iodine

2004 ◽  
Vol 4 (1) ◽  
pp. 939-967 ◽  
Author(s):  
G. McFiggans ◽  
H. Coe ◽  
R. Burgess ◽  
J. Allan ◽  
M. Cubison ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Forcing ◽  
Particle Production ◽  
Marine Boundary Layer ◽  
Cloud Condensation Nuclei ◽  
Ultrafine Particle ◽  
Molecular Iodine ◽  
Photo Oxidation ◽  
Coastal Boundary Layer ◽  
Coastal Boundary

Abstract. Renewal of ultrafine aerosols in the marine boundary layer may lead to repopulation of the marine distribution and ultimately determine the concentration of cloud condensation nuclei (CCN). Thus the formation of nanometre-scale particles can lead to enhanced scattering of incoming radiation and a net cooling of the atmosphere. The recent demonstration of the chamber formation of new particles from the photolytic production of condensable iodine-containing compounds from diiodomethane (CH2I2), (O'Dowd et al., 2002; Kolb, 2002; Jimenez et al., 2003a; Burkholder and Ravishankara, 2003), provides an additional mechanism to the gas-to-particle conversion of sulphuric acid formed in the photo-oxidation of dimethylsulphide for marine aerosol repopulation. CH2I2 is emitted from seaweeds (Carpenter et al., 1999, 2000) and has been suggested as an initiator of particle formation. We demonstrate here for the first time that ultrafine iodine-containing particles are produced by intertidal macroalgae exposed to ambient levels of ozone. The particle composition is very similar both to those formed in the chamber photo-oxidation of diiodomethane and in the oxidation of molecular iodine by ozone. The particles formed in all three systems are similarly aspherical and behave alike when exposed to increased humidity environments. Direct coastal boundary layer observations of molecular iodine, ultrafine particle production and iodocarbons are reported. Using a newly measured molecular iodine photolysis rate, it is shown that, if atomic iodine is involved in the observed particle bursts, it is of the order of at least 1000 times more likely to result from molecular iodine photolysis than diiodomethane photolysis. A hypothesis for molecular iodine release from intertidal macroalgae is presented and the potential importance of macroalgal iodine particles in their contribution to CCN and global radiative forcing are discussed.

scholarly journals Estimation of Reactive Inorganic Iodine Fluxes in the Indian and Southern Ocean Marine Boundary Layer

2020 ◽  
Author(s):  
Swaleha Inamdar ◽  
Liselotte Tinel ◽  
Rosie Chance ◽  
Lucy J. Carpenter ◽  
Prabhakaran Sabu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Southern Ocean ◽  
Marine Boundary Layer ◽  
Molecular Iodine ◽  
Polar Front ◽  
Sea Surface ◽  
Surface Seawater ◽  
Significance Level ◽  
Iodine Species ◽  
Iodine Chemistry

Abstract. Iodine chemistry has noteworthysignificant impacts on the oxidising capacity of the marine boundary layer (MBL) through the depletion of ozone (O3) and changes to HOx (OH/HO2) and NOx (NO/NO2) ratios. Hitherto, studies have shown that the reaction of atmospheric O3 with surface seawater iodide (I−) contributes to the flux of iodine species into the MBL mainly as hypoiodous acid (HOI) and molecular iodine (I2). Here, we present the first concomitant observations of iodine oxide (IO), O3 in the gas phase, and sea surface iodide concentrations. The results from three field campaigns in the Indian Ocean and the Southern Ocean during 2014–2017 are used to compute reactive iodine fluxes to the MBL. Observations of atmospheric IO by MAX-DOAS show active iodine chemistry in this environment, with IO values up to 1 pptv (parts per trillion by volume) below latitudes of 40° S. In order to compute the sea-to-air iodine flux supporting this chemistry, we compare previously established global sea surface iodide parameterisations with new, region-specific parameterisations based on the new iodide observations. This study shows that regional changes in salinity and sea surface temperature play a role in surface seawater iodide estimation. Sea-air fluxes of HOI and I2, calculated from the atmospheric ozone and seawater iodide concentrations (observed and predicted), failed to adequately explain the detected IO in this region. This discrepancy highlights the need to measure direct fluxes of inorganic and organic iodine species in the marine environment. Amongst other potential drivers of reactive iodine chemistry investigated, chlorophyll-a showed a significant correlation with atmospheric IO (R = 0.7 above the 99 % significance level) to the north of the polar front. This correlation might be indicative of a biogenic control on iodine sources in this region.

scholarly journals Isoprene suppression of new particle formation in a mixed deciduous forest

2011 ◽  
Vol 11 (12) ◽  
pp. 6013-6027 ◽  
Author(s):  
V. P. Kanawade ◽  
B. T. Jobson ◽  
A. B. Guenther ◽  
M. E. Erupe ◽  
S. N. Pressley ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Ultrafine Particles ◽  
Deciduous Forest ◽  
Cloud Condensation Nuclei ◽  
Ultrafine Particle ◽  
Underlying Mechanism ◽  
Particle Formation ◽  
Formation Mechanisms ◽  
New Particle Formation ◽  
Mixed Deciduous Forest

Abstract. Production of new particles over forests is an important source of cloud condensation nuclei that can affect climate. While such particle formation events have been widely observed, their formation mechanisms over forests are poorly understood. Our observations made in a mixed deciduous forest with large isoprene emissions during the summer displayed a surprisingly rare occurrence of new particle formation (NPF). Typically, NPF events occur around noon but no NPF events were observed during the 5 weeks of measurements. The exceptions were two evening ultrafine particle events. During the day, sulfuric acid concentrations were in the 106 cm−3 range with very low preexisting aerosol particles, a favorable condition for NPF to occur even during the summer. The ratio of emitted isoprene carbon to monoterpene carbon at this site was similar to that in Amazon rainforests (ratio >10), where NPF events are also very rare, compared with a ratio <0.5 in Finland boreal forests, where NPF events are frequent. Our results suggest that large isoprene emissions can suppress NPF formation in forests although the underlying mechanism for the suppression is unclear. The two evening ultrafine particle events were associated with the transported anthropogenic sulfur plumes and ultrafine particles were likely formed via ion-induced nucleation. Changes in landcover and environmental conditions could modify the isoprene suppression of NPF in some forest regions resulting in a radiative forcing that could have influence on the climate.

scholarly journals The first steps of iodine gas-to-particle conversion as seen in the lab: constraints on the role of iodine oxides and oxyacids

2020 ◽  
Author(s):  
Juan Carlos Gomez Martin ◽  
Tom Lewis ◽  
Manoj Kumar ◽  
John Plane ◽  
Joseph Francisco ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Gas Phase ◽  
Marine Boundary Layer ◽  
Oxide Particle ◽  
Molecular Iodine ◽  
Chem Phys ◽  
Particle Formation ◽  
Atmospheric Modeling ◽  
Atmospheric Environment ◽  
Iodine Oxides

&lt;p&gt;The photooxidation of gas phase iodine-bearing molecules emitted by marine biota leads to intense particle nucleation events in the coastal and polar marine boundary layer&lt;sup&gt;1-3&lt;/sup&gt;. The ubiquity of iodine in the marine atmospheric environment&lt;sup&gt;4-7&lt;/sup&gt; has suggested that this may be a previously unrecognized global source of new aerosol particles&lt;sup&gt;8&lt;/sup&gt;. Atmospheric modeling is required in order to evaluate the importance of this process, but a substantial lack of understanding of the gas-to-particle conversion mechanism is hindering this effort, especially regarding the gas phase chemistry of the nucleating molecules (iodine oxides&lt;sup&gt;9&lt;/sup&gt;&lt;sup&gt;,&lt;/sup&gt;&lt;sup&gt;10&lt;/sup&gt; and/or oxyacids&lt;sup&gt;7&lt;/sup&gt;) and the formation kinetics of molecular clusters. To address this problem, we have conducted new flow tube laboratory experiments where pulsed laser photolysis or continuous broad-band photolysis of I&lt;sub&gt;2&lt;/sub&gt;/O&lt;sub&gt;3&lt;/sub&gt; mixtures&amp;#160; in air are used to generate iodine radicals in the presence of atmospherically representative mixing ratios of water vapor. The molecular reactants and the resulting molecular products are detected by time-resolved VUV laser photo-ionization time-of-flight mass spectrometry. High-level quantum chemistry and master equation calculations and gas kinetics modelling are used to analyse the experimental data. In this presentation we discuss our results and their implications for the interpretation of field meassurements and for the implementatiion of an iodine oxide particle formation mechanism in atmospheric models.&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;1. Hoffmann, T., O'Dowd, C. D. &amp; Seinfeld, J. H. Iodine oxide homogeneous nucleation: An explanation for coastal new particle production. Geophys. Res. Lett. &lt;strong&gt;28&lt;/strong&gt;, 1949-1952 (2001).&lt;/p&gt;&lt;p&gt;2. McFiggans, G. et al. Direct evidence for coastal iodine particles from Laminaria macroalgae - linkage to emissions of molecular iodine. Atmos. Chem. Phys. &lt;strong&gt;4&lt;/strong&gt;, 701-713 (2004).&lt;/p&gt;&lt;p&gt;3. O'Dowd, C. D. et al. Marine aerosol formation from biogenic iodine emissions. Nature &lt;strong&gt;417&lt;/strong&gt;, 632-636 (2002).&lt;/p&gt;&lt;p&gt;4. Prados-Roman, C. et al. Iodine oxide in the global marine boundary layer. Atmos. Chem. Phys. &lt;strong&gt;15&lt;/strong&gt;, 583-593, doi:10.5194/acp-15-583-2015 (2015).&lt;/p&gt;&lt;p&gt;5. Sch&amp;#246;nhardt, A. et al. Simultaneous satellite observations of IO and BrO over Antarctica. Atmos. Chem. Phys. &lt;strong&gt;12&lt;/strong&gt;, 6565-6580, doi:10.5194/acp-12-6565-2012 (2012).&lt;/p&gt;&lt;p&gt;6. Mahajan, A. S. et al. Concurrent observations of atomic iodine, molecular iodine and ultrafine particles in a coastal environment. Atmos. Chem. Phys. &lt;strong&gt;10&lt;/strong&gt;, 27227-27253 (2010).&lt;/p&gt;&lt;p&gt;7. Sipil&amp;#228;, M. et al. Molecular-scale evidence of aerosol particle formation via sequential addition of HIO3. Nature &lt;strong&gt;537&lt;/strong&gt;, 532-534, doi:10.1038/nature19314 (2016).&lt;/p&gt;&lt;p&gt;8. Saiz-Lopez, A. et al. Atmospheric Chemistry of Iodine. Chem. Rev. &lt;strong&gt;112&lt;/strong&gt;, 1773&amp;#8211;1804, doi:DOI: 10.1021/cr200029u (2012).&lt;/p&gt;&lt;p&gt;9. G&amp;#243;mez Mart&amp;#237;n, J. C. et al. On the mechanism of iodine oxide particle formation. Phys. Chem. Chem. Phys. &lt;strong&gt;15&lt;/strong&gt;, 15612-15622, doi:10.1039/c3cp51217g (2013).&lt;/p&gt;&lt;p&gt;10. Saunders, R. W., Mahajan, A. S., G&amp;#243;mez Mart&amp;#237;n, J. C., Kumar, R. &amp; Plane, J. M. C. Studies of the Formation and Growth of Aerosol from Molecular Iodine Precursor. Z. Phys. Chem. &lt;strong&gt;224&lt;/strong&gt;, 1095-1117 (2010).&lt;/p&gt;

scholarly journals Isoprene suppression of new particle formation in mixed deciduous forest

2011 ◽  
Vol 11 (4) ◽  
pp. 11039-11075 ◽  
Author(s):  
V. P. Kanawade ◽  
B. Tom Jobson ◽  
A. B. Guenther ◽  
M. E. Erupe ◽  
S. N. Pressely ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Radiative Forcing ◽  
Ultrafine Particles ◽  
Deciduous Forest ◽  
Cloud Condensation Nuclei ◽  
Ultrafine Particle ◽  
Underlying Mechanism ◽  
Particle Formation ◽  
Formation Mechanisms ◽  
New Particle Formation

Abstract. Production of new particles over forests is an important source of cloud condensation nuclei that can affect climate. While such particle formation events have been widely observed, their formation mechanisms over forests are poorly understood. Our observations made in a mixed deciduous Michigan forest with large isoprene emissions during the summer show surprisingly rare occurrence of new particle formation (NPF). No NPF events were observed during the 5 weeks of measurements, except two evening ultrafine particle events as opposed to the typically observed noontime NPF elsewhere. Sulfuric acid concentrations were in the 106 cm−3 ranges with very low preexisting aerosol particles, a favorable condition for NPF to occur even during the summer. The ratio of emitted isoprene carbon to monoterpene carbon at this site was similar to that in Amazon rainforests (ratio >10), where NPF is also very rare, compared with a ratio <0.5 in Finland boreal forests, where NPF events are frequent. Our results showed that large isoprene emissions can suppress NPF formation in forests although the underlying mechanism for the suppression is unclear and future studies are needed to reveal the likely mechanism. The two evening ultrafine particle events were associated with the transported anthropogenic sulfur plumes and the ultrafine particles likely formed via ion induced nucleation. Changes in landcover and environmental conditions could modify the isoprene suppression of NPF in some forest regions resulting in a radiative forcing that could influence climate.

scholarly journals Factors controlling marine aerosol size distributions and their climate effects over the Northwest Atlantic Ocean region

2020 ◽  
Author(s):  
Betty Croft ◽  
Randall V. Martin ◽  
Richard H. Moore ◽  
Luke D. Ziemba ◽  
Ewan C. Crosbie ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Phytoplankton Bloom ◽  
Cloud Condensation Nuclei ◽  
Particle Formation ◽  
Size Distributions ◽  
Key Factors ◽  
Radiative Effects ◽  
Northwest Atlantic ◽  
Ocean Region

Abstract. Aerosols over Earth's remote and spatially extensive ocean surfaces have important influences on planetary climate. However, these aerosols and their effects remain poorly understood, in part due to the remoteness and limited observations over these regions. In this study, we seek to understand factors that shape marine aerosol size distributions and composition in the Northwest Atlantic Ocean region. We use the GEOS-Chem-TOMAS model to interpret measurements collected from ship and aircraft during the four seasonal campaigns of the North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) conducted between 2015 and 2018. Observations from the NAAMES campaigns show enhancements in aerosol total number concentration at atmospheric altitudes of about 1 km, most pronounced during the phytoplankton bloom maxima (May/June). Our simulations, combined with NAAMES ship and aircraft measurements, suggest several key factors contribute to aerosol number and size in the Northwest Atlantic lower troposphere, with significant regional-mean (40–60° N, 20–50° W) aerosol-cloud albedo indirect effects (AIE) and direct radiative effects (DRE) during the phytoplankton bloom. These key factors and their associated radiative effects in the region are: (1) particle formation above/near the marine boundary layer (MBL) top (AIE: −3.37 W m−2, DRE: −0.62 W m−2), (2) particle growth due to marine secondary organic aerosol (MSOA) as the nascent particles subside into the MBL, enabling them to become cloud-condensation-nuclei-size particles (AIE: −2.27 W m−2, DRE: −0.10 W m−2), (3) particle formation/growth due to the products of dimethyl sulfide, above/within the MBL (−1.29 W m−2, DRE: −0.06 W m−2), and (4) ship emissions (AIE: −0.62 W m−2, DRE: −0.05 W m−2). Our results suggest a synergy of particle formation near the MBL top and growth by MSOA that contributes strongly to cloud-condensation-nuclei-sized particles with significant regional radiative effects in the Northwest Atlantic. Future work is needed to understand the sources and temperature-dependence of condensable marine vapors forming MSOA and to understand the species that can form new particles at the boundary layer top and grow these particles as they descend into the marine boundary layer.

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