Elemental gas phase atmospheric mercury as it interacts with the ambient aerosol and its subsequent speciation and deposition

2000 ◽  
Vol 259 (1-3) ◽  
pp. 211-222 ◽  
Author(s):  
Luigi Forlano ◽  
Ian M. Hedgecock ◽  
Nicola Pirrone
Keyword(s):  
Gas Phase ◽  
Atmospheric Mercury ◽  
Ambient Aerosol

scholarly journals Global atmospheric model for mercury including oxidation by bromine atoms

2010 ◽  
Vol 10 (24) ◽  
pp. 12037-12057 ◽  
Author(s):  
C. D. Holmes ◽  
D. J. Jacob ◽  
E. S. Corbitt ◽  
J. Mao ◽  
X. Yang ◽  
...  
Keyword(s):  
Gas Phase ◽  
Atmospheric Model ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Deposition Flux ◽  
Mercury Deposition ◽  
Photochemical Reduction ◽  
Global Atmospheric Model ◽  
Summer Maximum ◽  
Southeast Us

Abstract. Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII and thus driving mercury deposition to ecosystems. However, thermodynamic considerations argue against the importance of these reactions. We demonstrate here the viability of atomic bromine (Br) as an alternative Hg0 oxidant. We conduct a global 3-D simulation with the GEOS-Chem model assuming gas-phase Br to be the sole Hg0 oxidant (Hg + Br model) and compare to the previous version of the model with OH and ozone as the sole oxidants (Hg + OH/O3 model). We specify global 3-D Br concentration fields based on our best understanding of tropospheric and stratospheric Br chemistry. In both the Hg + Br and Hg + OH/O3 models, we add an aqueous photochemical reduction of HgII in cloud to impose a tropospheric lifetime for mercury of 6.5 months against deposition, as needed to reconcile observed total gaseous mercury (TGM) concentrations with current estimates of anthropogenic emissions. This added reduction would not be necessary in the Hg + Br model if we adjusted the Br oxidation kinetics downward within their range of uncertainty. We find that the Hg + Br and Hg + OH/O3 models are equally capable of reproducing the spatial distribution of TGM and its seasonal cycle at northern mid-latitudes. The Hg + Br model shows a steeper decline of TGM concentrations from the tropics to southern mid-latitudes. Only the Hg + Br model can reproduce the springtime depletion and summer rebound of TGM observed at polar sites; the snowpack component of GEOS-Chem suggests that 40% of HgII deposited to snow in the Arctic is transferred to the ocean and land reservoirs, amounting to a net deposition flux to the Arctic of 60 Mg a−1. Summertime events of depleted Hg0 at Antarctic sites due to subsidence are much better simulated by the Hg + Br model. Model comparisons to observed wet deposition fluxes of mercury in the US and Europe show general consistency. However the Hg + Br model does not capture the summer maximum over the southeast US because of low subtropical Br concentrations while the Hg + OH/O3 model does. Vertical profiles measured from aircraft show a decline of Hg0 above the tropopause that can be captured by both the Hg + Br and Hg + OH/O3 models, except in Arctic spring where the observed decline is much steeper than simulated by either model; we speculate that oxidation by Cl species might be responsible. The Hg + Br and Hg + OH/O3 models yield similar global budgets for the cycling of mercury between the atmosphere and surface reservoirs, but the Hg + Br model results in a much larger fraction of mercury deposited to the Southern Hemisphere oceans.

scholarly journals Gas-Phase Photolysis of Hg(I) Radical Species: A New Atmospheric Mercury Reduction Process

2019 ◽  
Vol 141 (22) ◽  
pp. 8698-8702 ◽  
Author(s):  
Alfonso Saiz-Lopez ◽  
A. Ulises Acuña ◽  
Tarek Trabelsi ◽  
Javier Carmona-García ◽  
Juan Z. Dávalos ◽  
...  
Keyword(s):  
Gas Phase ◽  
Reduction Process ◽  
Atmospheric Mercury ◽  
Radical Species ◽  
Mercury Reduction

scholarly journals Campholenic aldehyde ozonolysis: a mechanism leading to specific biogenic secondary organic aerosol constituents

2014 ◽  
Vol 14 (2) ◽  
pp. 719-736 ◽  
Author(s):  
A. Kahnt ◽  
Y. Iinuma ◽  
A. Mutzel ◽  
O. Böge ◽  
M. Claeys ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Negative Ion ◽  
Mass Spectrometry Analysis ◽  
Radical Scavenger ◽  
Ambient Aerosol ◽  
Campholenic Aldehyde

Abstract. In the present study, campholenic aldehyde ozonolysis was performed to investigate pathways leading to specific biogenic secondary organic aerosol (SOA) marker compounds. Campholenic aldehyde, a known α-pinene oxidation product, is suggested to be a key intermediate in the formation of terpenylic acid upon α-pinene ozonolysis. It was reacted with ozone in the presence and absence of an OH radical scavenger, leading to SOA formation with a yield of 0.75 and 0.8, respectively. The resulting oxidation products in the gas and particle phases were investigated employing a denuder/filter sampling combination. Gas-phase oxidation products bearing a carbonyl group, which were collected by the denuder, were derivatised by 2,4-dinitrophenylhydrazine (DNPH) followed by liquid chromatography/negative ion electrospray ionisation time-of-flight mass spectrometry analysis and were compared to the gas-phase compounds detected by online proton-transfer-reaction mass spectrometry. Particle-phase products were also analysed, directly or after DNPH derivatisation, to derive information about specific compounds leading to SOA formation. Among the detected compounds, the aldehydic precursor of terpenylic acid was identified and its presence was confirmed in ambient aerosol samples from the DNPH derivatisation, accurate mass data, and additional mass spectrometry (MS2 and MS3 fragmentation studies). Furthermore, the present investigation sheds light on a reaction pathway leading to the formation of terpenylic acid, involving α-pinene, α-pinene oxide, campholenic aldehyde, and terpenylic aldehyde. Additionally, the formation of diaterpenylic acid acetate could be connected to campholenic aldehyde oxidation. The present study also provides insights into the source of other highly functionalised oxidation products (e.g. m / z 201, C9H14O5 and m / z 215, C10H16O5), which have been observed in ambient aerosol samples and smog chamber-generated monoterpene SOA. The m / z 201 and 215 compounds were tentatively identified as a C9- and C10-carbonyl-dicarboxylic acid, respectively, based on reaction mechanisms of campholenic aldehyde and ozone, as well as detailed interpretation of mass spectral data, in conjunction with the formation of corresponding DNPH derivatives.

scholarly journals An investigation of the origins of reactive gaseous mercury in the Mediterranean marine boundary layer

2009 ◽  
Vol 9 (6) ◽  
pp. 24815-24846 ◽  
Author(s):  
F. Sprovieri ◽  
I. M. Hedgecock ◽  
N. Pirrone
Keyword(s):  
Gas Phase ◽  
Marine Boundary Layer ◽  
Atmospheric Mercury ◽  
Chemical Mechanism ◽  
Back Trajectory ◽  
Emission Sources ◽  
Anthropogenic Emission ◽  
Modelling Studies ◽  
In Situ Production

Abstract. Atmospheric mercury concentrations were measured during two oceanographic cruise campaigns covering the Adriatic Sea, the first during the autumn in 2004 and the second in the summer of 2005. The inclement weather during the autumn campaign meant that no clear in-situ production of oxidised gas phase mercury was seen, and that events where high values of HgII(g) and/or Hg associated with particulates (HgP) were observed, were the result of plumes from anthropogenic emission sources. During the summer campaign however, the by now rather familiar diurnal variation of HgII(g) concentration, with maxima around midday, was observed. Again there were events when high HgII(g) and particulates (HgP) concentrations were seen which did not fit with the pattern of daily in-situ HgII(g) production, which were traceable, with the help of back trajectory calculations, to anthropogenic emission sources. All the emission plumes encountered could be traced back to ports, not all of which are associated with major industrial installations. It therefore seems likely in theses cases that the emissions are either due to shipping or to port activities. Box modelling studies of the summer 2005 campaign show that although the in-situ production of HgII(g) occurs in the MBL, the exact chemical mechanism responsible is difficult to determine. However given the high O3 concentrations encountered during this campaign it seems clear that if Hg0 does react with O3, it does not produce gas phase HgII, and the reaction between Hg0 and OH if it occurs, does not contribute appreciably to HgII(g) production.

scholarly journals Campholenic aldehyde ozonolysis: a possible mechanism for the formation of specific biogenic secondary organic aerosol constituents

2013 ◽  
Vol 13 (8) ◽  
pp. 22487-22534
Author(s):  
A. Kahnt ◽  
Y. Iinuma ◽  
A. Mutzel ◽  
O. Böge ◽  
M. Claeys ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Negative Ion ◽  
Mass Spectrometry Analysis ◽  
Radical Scavenger ◽  
Ambient Aerosol ◽  
Campholenic Aldehyde

Abstract. In the present study, campholenic aldehyde ozonolysis was performed to investigate pathways leading to specific biogenic secondary organic aerosol (SOA) marker compounds. Campholenic aldehyde, a known α-pinene oxidation product, is suggested to be a key intermediate in the formation of terpenylic acid upon α-pinene ozonolysis. It was reacted with ozone in the presence and absence of an OH radical scavenger leading to SOA formation with a yield of 0.75 and 0.8, respectively. The resulting oxidation products in the gas and particle phases were investigated employing a denuder/filter sampling combination. Gas-phase oxidation products bearing a carbonyl group, which were collected by the denuder, were derivatised with 2,4-dinitrophenylhydrazine (DNPH) followed by Liquid Chromatography/negative ion Electrospray Ionisation Time-of-Flight Mass Spectrometry analysis and were compared to the gas-phase compounds detected by online Proton-Transfer-Reaction Mass Spectrometry. Particle-phase products were also analysed, directly or after DNPH derivatisation, to derive information about specific compounds leading to SOA formation. Among the detected compounds, the aldehydic precursor of terpenylic acid was identified and its presence was confirmed in ambient aerosol samples from the DNPH derivatisation, accurate mass data, and MS2 and MS3 fragmentation studies. Furthermore, the present investigation sheds light on a reaction pathway leading to the formation of terpenylic acid, involving α-pinene, α-pinene oxide, campholenic aldehyde, and terpenylic aldehyde. Additionally, the formation of diaterpenylic acid acetate could be connected to campholenic aldehyde oxidation. The present study also provides insights into the source of other highly functionalised oxidation products (e.g. m/z 201, C9H14O5 and m/z 215, C10H16O5), which have been observed in ambient aerosol samples and smog chamber-generated monoterpene SOA. The m/z 201 and 215 compounds were tentatively identified as a C9- and C10-carbonyl-dicarboxylic acid, respectively, based on reaction mechanisms of campholenic aldehyde and ozone, detailed interpretation of mass spectral data, in conjunction with the formation of corresponding DNPH-derivatives.

The role of ambient aerosol characteristics in the speciation of atmospheric mercury

1999 ◽  
Vol 30 ◽  
pp. S463-S464 ◽  
Author(s):  
I. Hedgecock ◽  
L. Forlano ◽  
N. Pirrone
Keyword(s):  
Atmospheric Mercury ◽  
Ambient Aerosol

Towards an advanced description and modelling of the atmospheric multiphase chemistry of mercury: CAPRAM HG module 1.0

2021 ◽  
Author(s):  
Erik Hans Hoffmann ◽  
Tao Li ◽  
Andreas Tilgner ◽  
Yan Wang ◽  
Hartmut Herrmann
Keyword(s):  
Gas Phase ◽  
Aqueous Phase ◽  
Aerosol Particles ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
Gas Phase Reactions ◽  
Gaseous Elemental Mercury ◽  
Gas Phase Chemistry ◽  
Reactive Halogen Species ◽  
Phase Chemistry

<p>Mercury is a neurotoxic element emitted predominantly in its less-reactive form as gaseous elemental mercury (GEM) into the atmosphere by various natural and anthropogenic processes. Once emitted it undergoes chemical processing in the atmospheric gas and aqueous phase. There, GEM is oxidised into gaseous oxidised mercury (GOM), which partitions into aerosol particles residing there as particulate bounded mercury (PBM) due to its much higher solubility. The faster deposition of GOM and PBM compared to GEM is of special environmental importance, because they can be converted into more toxic organic mercury in aquatic environments and then take serious place in the food web. Thus, it is crucial for models to understand the transformation of GEM into GOM and PBM and vice versa. To date, numerous gas-phase chemistry simulations were performed, but reveal missing oxidation and reduction processes. However, only few models exist that investigate the multiphase mercury chemistry in a detailed manner.</p><p>Therefore, a comprehensive multiphase mercury chemistry mechanism, the CAPRAM HG module 1.0 (CAPRAM-HG1.0), has been developed. The CAPRAM-HG1.0 includes 74 gas-phase reactions, 22 phase transfers and 77 aqueous-phase reactions. It was coupled to the multiphase chemistry mechanism MCMv3.2/CAPRAM4.0 and the extended CAPRAM halogen module 3.0 (CAPRAM-HM3.0) for investigations of multiphase Hg redox under Chinese polluted conditions. Simulations were performed for summer conditions in 2014 using the air parcel model SPACCIM to investigate the performance of the model to simulate typical concentrations and patterns of GEM, GOM and PBM.</p><p>Under non-cloud conditions, model results reveal good coincides with concentrations and patterns for GEM, GOM and PBM measured in China. However, the simulations also show that there are still high uncertainties in atmospheric mercury chemistry. Especially, the complexation with HULIS within aerosol particles needs evaluation as the simulations indicate this process as key process driving concentrations and patterns of both GOM and PBM. Further, the present study demonstrates the need of a better understanding of continental concentrations of reactive halogen species and particle bounded halides as well as their link to the multiphase chemistry and atmospheric cycling of mercury.</p>

scholarly journals Air–snowpack exchange of bromine, ozone and mercury in the springtime Arctic simulated by the 1-D model PHANTAS – Part 1: In-snow bromine activation and its impact on ozone

2014 ◽  
Vol 14 (8) ◽  
pp. 4101-4133 ◽  
Author(s):  
K. Toyota ◽  
J. C. McConnell ◽  
R. M. Staebler ◽  
A. P. Dastoor
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Gas Phase ◽  
Aqueous Phase ◽  
Ambient Air ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Radical Chemistry ◽  
Ozone Loss ◽  
Key Species

Abstract. To provide a theoretical framework towards a better understanding of ozone depletion events (ODEs) and atmospheric mercury depletion events (AMDEs) in the polar boundary layer, we have developed a one-dimensional model that simulates multiphase chemistry and transport of trace constituents from porous snowpack and through the atmospheric boundary layer (ABL) as a unified system. This paper constitutes Part 1 of the study, describing a general configuration of the model and the results of simulations related to reactive bromine release from the snowpack and ODEs during the Arctic spring. A common set of aqueous-phase reactions describes chemistry both within the liquid-like layer (LLL) on the grain surface of the snowpack and within deliquesced "haze" aerosols mainly composed of sulfate in the atmosphere. Gas-phase reactions are also represented by the same mechanism in the atmosphere and in the snowpack interstitial air (SIA). Consequently, the model attains the capacity of simulating interactions between chemistry and mass transfer that become particularly intricate near the interface between the atmosphere and the snowpack. In the SIA, reactive uptake on LLL-coated snow grains and vertical mass transfer act simultaneously on gaseous HOBr, a fraction of which enters from the atmosphere while another fraction is formed via gas-phase chemistry in the SIA itself. A "bromine explosion", by which HOBr formed in the ambient air is deposited and then converted heterogeneously to Br2, is found to be a dominant process of reactive bromine formation in the top 1 mm layer of the snowpack. Deeper in the snowpack, HOBr formed within the SIA leads to an in-snow bromine explosion, but a significant fraction of Br2 is also produced via aqueous radical chemistry in the LLL on the surface of the snow grains. These top- and deeper-layer productions of Br2 both contribute to the release of Br2 to the atmosphere, but the deeper-layer production is found to be more important for the net outflux of reactive bromine. Although ozone is removed via bromine chemistry, it is also among the key species that control both the conventional and in-snow bromine explosions. On the other hand, aqueous-phase radical chemistry initiated by photolytic OH formation in the LLL is also a significant contributor to the in-snow source of Br2 and can operate without ozone, whereas the delivery of Br2 to the atmosphere becomes much smaller after ozone is depleted. Catalytic ozone loss via bromine radical chemistry occurs more rapidly in the SIA than in the ambient air, giving rise to apparent dry deposition velocities for ozone from the air to the snow on the order of 10−3 cm s−1 during daytime. Overall, however, the depletion of ozone in the system is caused predominantly by ozone loss in the ambient air. Increasing depth of the turbulent ABL under windy conditions will delay the buildup of reactive bromine and the resultant loss of ozone, while leading to the higher column amount of BrO in the atmosphere. During the Arctic spring, if moderately saline and acidic snowpack is as prevalent as assumed in our model runs on sea ice, the shallow, stable ABL under calm weather conditions may undergo persistent ODEs without substantial contributions from blowing/drifting snow and wind-pumping mechanisms, whereas the column densities of BrO in the ABL will likely remain too low in the course of such events to be detected unambiguously by satellite nadir measurements.

scholarly journals An investigation of the origins of reactive gaseous mercury in the Mediterranean marine boundary layer

2010 ◽  
Vol 10 (8) ◽  
pp. 3985-3997 ◽  
Author(s):  
F. Sprovieri ◽  
I. M. Hedgecock ◽  
N. Pirrone
Keyword(s):  
Gas Phase ◽  
Marine Boundary Layer ◽  
Atmospheric Mercury ◽  
Chemical Mechanism ◽  
Back Trajectory ◽  
Mercury Species ◽  
Back Trajectories ◽  
Trajectory Calculations ◽  
In Situ Production

Abstract. Atmospheric mercury species concentrations were measured during two oceanographic cruise campaigns covering the Adriatic Sea, the first during the autumn in 2004 and the second in the summer of 2005. The inclement weather during the autumn campaign meant that no clear in-situ production of oxidised gas phase mercury was seen. Events where high values of HgII(g) and/or Hg associated with particulates (HgP) were observed, could be linked to probable anthropogenic emission source areas. During the summer campaign however, the by now rather familiar diurnal variation of HgII(g) concentration, with maxima around midday, was observed. Again there were events when high HgII(g) and particulates (HgP) concentrations were seen which did not fit with the pattern of daily in-situ HgII(g) production. These events were traceable, with the help of back trajectory calculations, to areas of anthropogenic emissions. The back trajectories for all the events during which high Hg species concentrations were encountered showed that the airmass being sampled had passed near port areas in the previous 24 h. Not all these ports are associated with major industrial installations, it is possible therefore (bearing in mind the uncertainty associated with the back trajectory calculations) that either shipping or port activities are a Hg source. Box modelling studies of the summer 2005 campaign show that although the in-situ production of HgII(g) occurs in the MBL, the exact chemical mechanism responsible is difficult to determine. However given the high O3 concentrations encountered during this campaign it seems clear that if Hg0 does react with O3, it does not produce gas phase HgII. Equally, the reaction between Hg0 and OH if it occurs, does not contribute appreciably to HgII(g) production.

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