scholarly journals Total gaseous mercury depletion events observed at Cape Point during 2007–2008

2009 ◽  
Vol 9 (5) ◽  
pp. 20979-21009 ◽  
Author(s):  
E.-G. Brunke ◽  
C. Labuschagne ◽  
R. Ebinghaus ◽  
H. H. Kock ◽  
F. Slemr
Keyword(s):  
Marine Boundary Layer ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
Chemical Mechanism ◽  
Polar Regions ◽  
Air Masses ◽  
Transport Distance ◽  
Gaseous Mercury ◽  
Urban Emissions ◽  
Emission Ratios

Abstract. Gaseous mercury in the marine boundary layer has been measured with a 15 min temporal resolution at the Global Atmosphere Watch station Cape Point since March 2007. The most prominent features of the data until July 2008 are the frequent occurrences of pollution (PEs) and depletion events (DEs). Both types of events originate mostly within a short transport distance (up to about 100 km), which are embedded in air masses ranging from marine background to continental. The Hg/CO emission ratios observed during the PEs are within the range reported for biomass burning and industrial/urban emissions. The depletion of gaseous mercury during the DEs is almost quantitative in many cases and suggests a lifetime of elemental mercury as short as a few dozens of hours, which is in contrast to the commonly used estimate of approximately 1 year. The characteristics of the DE occurrence at Cape Point is neither similar to the halogen driven atmospheric mercury depletion events (AMDEs) observed in Polar Regions nor to the DEs reported for plumes of urban air. Additional measurements are necessary to reveal the chemical mechanism of the observed DEs and to assess its importance on larger scales.

scholarly journals Gaseous elemental mercury depletion events observed at Cape Point during 2007–2008

2010 ◽  
Vol 10 (3) ◽  
pp. 1121-1131 ◽  
Author(s):  
E.-G. Brunke ◽  
C. Labuschagne ◽  
R. Ebinghaus ◽  
H. H. Kock ◽  
F. Slemr
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
Chemical Mechanism ◽  
Polar Regions ◽  
Gaseous Elemental Mercury ◽  
Transport Distance ◽  
Gaseous Mercury ◽  
Urban Emissions

Abstract. Gaseous mercury in the marine boundary layer has been measured with a 15 min temporal resolution at the Global Atmosphere Watch station Cape Point since March 2007. The most prominent features of the data until July 2008 are the frequent occurrences of pollution (PEs) and depletion events (DEs). Both types of events originate mostly within a short transport distance (up to about 100 km), which are embedded in air masses ranging from marine background to continental. The Hg/CO emission ratios observed during the PEs are within the range reported for biomass burning and industrial/urban emissions. The depletion of gaseous mercury during the DEs is in many cases almost complete and suggests an atmospheric residence time of elemental mercury as short as a few dozens of hours, which is in contrast to the commonly used estimate of approximately 1 year. The DEs observed at Cape Point are not accompanied by simultaneous depletion of ozone which distinguishes them from the halogen driven atmospheric mercury depletion events (AMDEs) observed in Polar Regions. Nonetheless, DEs similar to those observed at Cape Point have also been observed at other places in the marine boundary layer. Additional measurements of mercury speciation and of possible mercury oxidants are hence called for to reveal the chemical mechanism of the newly observed DEs and to assess its importance on larger scales.

Gaseous mercury in coastal urban areas

2010 ◽  
Vol 7 (6) ◽  
pp. 537 ◽  
Author(s):  
Anne L. Soerensen ◽  
Henrik Skov ◽  
Matthew S. Johnson ◽  
Marianne Glasius
Keyword(s):  
Urban Areas ◽  
Marine Boundary Layer ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
Mercury Deposition ◽  
Mercury Emissions ◽  
Gaseous Elemental Mercury ◽  
Gaseous Mercury ◽  
Range Transport ◽  
Aquatic Food

Environmental context Mercury is a neurotoxin that bioaccumulates in the aquatic food web. Atmospheric emissions from urban areas close to the coast could cause increased local mercury deposition to the ocean. Our study adds important new data to the current limited knowledge on atmospheric mercury emissions and dynamics in coastal urban areas. Abstract Approximately 50% of primary atmospheric mercury emissions are anthropogenic, resulting from e.g. emission hotspots in urban areas. Emissions from urban areas close to the coast are of interest because they could increase deposition loads to nearby coastal waters as well as contribute to long range transport of mercury. We present results from measurements of gaseous elemental mercury (GEM) and reactive gaseous mercury (RGM) in 15 coastal cities and their surrounding marine boundary layer (MBL). An increase of 15–90% in GEM concentration in coastal urban areas was observed compared with the remote MBL. Strong RGM enhancements were only found in two cities. In urban areas with statistically significant GEM/CO enhancement ratios, slopes between 0.0020 and 0.0087 ng m–3 ppb–1 were observed, which is consistent with other observations of anthropogenic enhancement. The emission ratios were used to estimate GEM emissions from the areas. A closer examination of data from Sydney (Australia), the coast of Chile, and Valparaiso region (Chile) in the southern hemisphere, is presented.

scholarly journals Investigation of processes controlling GEM oxidation at mid-latitudinal marine, coastal, and inland sites

2016 ◽  
Author(s):  
Z. Ye ◽  
H. Mao ◽  
C.-J. Lin ◽  
S. Y. Kim
Keyword(s):  
Marine Boundary Layer ◽  
State Of The Art ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
Chemical Mechanism ◽  
Atmospheric Conditions ◽  
Gaseous Elemental Mercury ◽  
Mixing Ratios ◽  
Marine Site ◽  
Study Sites

Abstract. A box model incorporating a state-of-the-art chemical mechanism for atmospheric mercury (Hg) cycling was developed to investigate oxidation of gaseous elemental mercury (GEM) at three locations in the northeastern United States: Appledore Island (marine), Thompson Farm (coastal, rural), and Pack Monadnock (inland, rural, elevated). The chemical mechanism improved model's ability to simulate the formation of gaseous oxidized mercury (GOM) at the study sites. At the coastal and inland sites, GEM oxidation was predominated by O3 and OH, contributing 80–99 % of total GOM production during daytime. H2O2 initiated GEM oxidation was significant (~ 33 % of the total GOM) at the inland site during nighttime. In the marine boundary layer (MBL), Br and BrO were dominant GEM oxidants contributing ~ 70 % of the total GOM production during mid-day, while O3 dominated GEM oxidation (50–90 % of GOM production) over the remaining day. Following the production of HgBr from GEM + Br, HgBr was oxidized by BrO, HO2, OH, ClO, and IO to form Hg(II) brominated GOM species. However, under atmospheric conditions, the prevalent GEM oxidants in the MBL could be Br / BrO or O3 / OH depending on Br and BrO mixing ratios. Relative humidity and products of the CH3O2 + BrO reaction possibly affected significantly the mixing ratios of Br or BrO radicals and subsequently GOM formation. Gas-particle partitioning could be potentially important in the production of GOM as well as Br and BrO at the marine site.

scholarly journals Investigation of processes controlling summertime gaseous elemental mercury oxidation at midlatitudinal marine, coastal, and inland sites

2016 ◽  
Vol 16 (13) ◽  
pp. 8461-8478 ◽  
Author(s):  
Zhuyun Ye ◽  
Huiting Mao ◽  
Che-Jen Lin ◽  
Su Youn Kim
Keyword(s):  
Marine Boundary Layer ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
Box Model ◽  
Chemical Mechanism ◽  
Gaseous Elemental Mercury ◽  
Diurnal Cycles ◽  
Mixing Ratios ◽  
Halogen Chemistry ◽  
Marine Site

Abstract. A box model incorporating a state-of-the-art chemical mechanism for atmospheric mercury (Hg) cycling was developed to investigate the oxidation of gaseous elemental mercury (GEM) at three locations in the northeastern United States: Appledore Island (AI; marine), Thompson Farm (TF; coastal, rural), and Pack Monadnock (PM; inland, rural, elevated). The chemical mechanism in this box model included the most up-to-date Hg and halogen chemistry. As a result, the box model was able to simulate reasonably the observed diurnal cycles of gaseous oxidized mercury (GOM) and chemical speciation bearing distinct differences between the three sites. In agreement with observations, simulated GOM diurnal cycles at AI and TF showed significant daytime peaks in the afternoon and nighttime minimums compared to flat GOM diurnal cycles at PM. Moreover, significant differences in the magnitude of GOM diurnal amplitude (AI > TF > PM) were captured in modeled results. At the coastal and inland sites, GEM oxidation was predominated by O3 and OH, contributing 80–99 % of total GOM production during daytime. H2O2-initiated GEM oxidation was significant (∼ 33 % of the total GOM) at the inland site during nighttime. In the marine boundary layer (MBL) atmosphere, Br and BrO became dominant GEM oxidants, with mixing ratios reaching 0.1 and 1 pptv, respectively, and contributing ∼ 70 % of the total GOM production during midday, while O3 dominated GEM oxidation (50–90 % of GOM production) over the remaining day when Br and BrO mixing ratios were diminished. The majority of HgBr produced from GEM+Br was oxidized by NO2 and HO2 to form brominated GOM species. Relative humidity and products of the CH3O2+BrO reaction possibly significantly affected the mixing ratios of Br or BrO radicals and subsequently GOM formation. Gas–particle partitioning could potentially be important in the production of GOM as well as Br and BrO at the marine site.

scholarly journals A synthesis of atmospheric mercury depletion event chemistry linking atmosphere, snow and water

2007 ◽  
Vol 7 (4) ◽  
pp. 10837-10931 ◽  
Author(s):  
A. Steffen ◽  
T. Douglas ◽  
M. Amyot ◽  
P. Ariya ◽  
K. Aspmo ◽  
...  
Keyword(s):  
Sea Ice ◽  
Current Knowledge ◽  
Kinetic Studies ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Polar Regions ◽  
Environmental Media ◽  
Gaseous Elemental Mercury ◽  
History Of

Abstract. It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM) occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg). This phenomenon is termed atmospheric mercury depletion events (AMDEs) and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review the history of Hg in Polar Regions, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the roles that the snow pack, oceans, fresh water and the sea ice play in the cycling of Hg are presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not remain in the same form in the snow. Kinetic studies undertaken have demonstrated that bromine is the major oxidant depleting Hg in the atmosphere. Modeling results demonstrate that there is a significant deposition of Hg to Polar Regions as a result of AMDEs. Models have also shown that Hg is readily transported to the Arctic from source regions, at times during springtime when this environment is actively transforming Hg from the atmosphere to the snow and ice surfaces. The presence of significant amounts of methyl Hg in snow in the Arctic surrounding AMDEs is important because this species is the link between the environment and impacts to wildlife and humans. Further, much work on methylation and demethylation processes have occurred but are not yet fully understood. Recent changes in the climate and sea ice cover in Polar Regions are likely to have strong effects on the cycling of Hg in this environment; however more research is needed to understand Hg processes in order to formulate meaningful predictions of these changes. Mercury, Atmospheric mercury depletion events (AMDE), Polar, Arctic, Antarctic, Ice

Baseline atmospheric mercury studies at Ross Island, Antarctica

1993 ◽  
Vol 5 (3) ◽  
pp. 323-326 ◽  
Author(s):  
S. J. de Mora ◽  
J. E. Patterson ◽  
D. M. Bibby
Keyword(s):  
Mercury Concentration ◽  
Limit Of Detection ◽  
Atmospheric Mercury ◽  
Polar Regions ◽  
Total Gaseous Mercury ◽  
Gaseous Mercury

The first extended baseline studies of total gaseous mercury (TGM) and dimethylmercury (DMM) in Antarctica are reported. Mean TGM concentrations of 0.52, 0.60 and 0.52 ng m−3 were obtained for three consecutive years at the southern tip of Ross Island (77°S). The levels of DMM in Antarctica are less than 10% of the TGM, and frequently fall below the limit of detection. These results represent the lowest TGM concentrations recorded globally and extend into polar regions the observation of a decrease in atmospheric mercury concentration with increasing latitude.

scholarly journals A synthesis of atmospheric mercury depletion event chemistry in the atmosphere and snow

2008 ◽  
Vol 8 (6) ◽  
pp. 1445-1482 ◽  
Author(s):  
A. Steffen ◽  
T. Douglas ◽  
M. Amyot ◽  
P. Ariya ◽  
K. Aspmo ◽  
...  
Keyword(s):  
Sea Ice ◽  
Current Knowledge ◽  
Kinetic Studies ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Polar Regions ◽  
Environmental Media ◽  
Gaseous Elemental Mercury ◽  
Low Concentrations

Abstract. It was discovered in 1995 that, during the spring time, unexpectedly low concentrations of gaseous elemental mercury (GEM) occurred in the Arctic air. This was surprising for a pollutant known to have a long residence time in the atmosphere; however conditions appeared to exist in the Arctic that promoted this depletion of mercury (Hg). This phenomenon is termed atmospheric mercury depletion events (AMDEs) and its discovery has revolutionized our understanding of the cycling of Hg in Polar Regions while stimulating a significant amount of research to understand its impact to this fragile ecosystem. Shortly after the discovery was made in Canada, AMDEs were confirmed to occur throughout the Arctic, sub-Artic and Antarctic coasts. It is now known that, through a series of photochemically initiated reactions involving halogens, GEM is converted to a more reactive species and is subsequently associated to particles in the air and/or deposited to the polar environment. AMDEs are a means by which Hg is transferred from the atmosphere to the environment that was previously unknown. In this article we review Hg research taken place in Polar Regions pertaining to AMDEs, the methods used to collect Hg in different environmental media, research results of the current understanding of AMDEs from field, laboratory and modeling work, how Hg cycles around the environment after AMDEs, gaps in our current knowledge and the future impacts that AMDEs may have on polar environments. The research presented has shown that while considerable improvements in methodology to measure Hg have been made but the main limitation remains knowing the speciation of Hg in the various media. The processes that drive AMDEs and how they occur are discussed. As well, the role that the snow pack and the sea ice play in the cycling of Hg is presented. It has been found that deposition of Hg from AMDEs occurs at marine coasts and not far inland and that a fraction of the deposited Hg does not remain in the same form in the snow. Kinetic studies undertaken have demonstrated that bromine is the major oxidant depleting Hg in the atmosphere. Modeling results demonstrate that there is a significant deposition of Hg to Polar Regions as a result of AMDEs. Models have also shown that Hg is readily transported to the Arctic from source regions, at times during springtime when this environment is actively transforming Hg from the atmosphere to the snow and ice surfaces. The presence of significant amounts of methyl Hg in snow in the Arctic surrounding AMDEs is important because this species is the link between the environment and impacts to wildlife and humans. Further, much work on methylation and demethylation processes has occurred but these processes are not yet fully understood. Recent changes in the climate and sea ice cover in Polar Regions are likely to have strong effects on the cycling of Hg in this environment; however more research is needed to understand Hg processes in order to formulate meaningful predictions of these changes.

scholarly journals Circumpolar transport and air-surface exchange of atmospheric mercury at Ny-Ålesund (79° N), Svalbard, spring 2002

2007 ◽  
Vol 7 (1) ◽  
pp. 151-166 ◽  
Author(s):  
J. Sommar ◽  
I. Wängberg ◽  
T. Berg ◽  
K. Gårdfeldt ◽  
J. Munthe ◽  
...  
Keyword(s):  
Sea Level ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
Mercury Species ◽  
Research Station ◽  
Flux Chamber ◽  
Vertical Column ◽  
Surface Exchange ◽  
Lower Altitude ◽  
Gaseous Mercury

Abstract. Mercury in different environmental compartments has been measured at Ny-Ålesund (78°54' N, 11°53' E) during an intensive campaign, 17 April to 14 May 2002. Time-resolved speciated determination of mercury in the atmosphere and snow was conducted at the Norwegian research station at the Zeppelin mountain, 474 m above the sea level, and at the Italian research facility Dirigibile Italia, 12 m above the sea level. Total Gaseous Mercury (TGM) was present in the range <0.1 to 2.2 ng m−3 during the campaign. Three mercury depletion events, identified as periods with decreased TGM concentrations, were observed. At the lower altitude, TGM concentrations following such events were found to exhibit both higher magnitude and larger variability in comparison to results from the Zeppelin station. Oxidised mercury species in air and fall-out with snow as well as mercury attached to particles were also measured and their concentrations were found to be anti-correlated with TGM in air. concentrations of total Hg in snow (Hg-tot) showed a large (~15×) increase in response to Gaseous Elemental Mercury Depletion Events (GEMDEs, range 1.5–76.5 ng L−1). Solid evidence for photo-stimulated emissions of Hg0(g) from the snow pack in conjunction to depletion events were obtained from gradient measurements as well as from flux chamber measurements. Steep diurnal concentration variations of Hg0(aq) in surface seawater were also found to concur with changing solar radiation. The concentration of Hg0(aq) in seawater was found to be in the range 12.2–70.4 pg L−1, which corresponds to supersaturation. Hence, the seawater surface constituted a source emitting elemental mercury. The concentrations of RGM (reactive gaseous mercury), Hg-p (particulate mercury), and BrO column densities (detected by DOAS) were very low except for a few individual samples during the major Hg0 depletion event. BrO vertical column densities obtained by the remote satellite ESR-2 and trajectory analysis indicate that the air masses exhibiting low Hg0 concentrations originated from areas with high BrO densities.

scholarly journals Observation and analysis of speciated atmospheric mercury in Shangri-la, Tibetan Plateau, China

2014 ◽  
Vol 14 (8) ◽  
pp. 11041-11074 ◽  
Author(s):  
H. Zhang ◽  
X. W. Fu ◽  
C.-J. Lin ◽  
X. Wang ◽  
X. B. Feng
Keyword(s):  
Tibetan Plateau ◽  
Atmospheric Transport ◽  
Seasonal Pattern ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
North India ◽  
Air Masses ◽  
Gaseous Elemental Mercury ◽  
Wet Scavenging ◽  
In The Beginning

Abstract. This study reports the speciated concentration and the potential sources of atmospheric mercury measured at the Shangri-La Atmosphere Watch Regional Station (SAWRS), a pristine high-altitude site (3580 m a.s.l.) in Tibetan Plateau, China. The total gaseous mercury (TGM, defined as the sum of Gaseous Elemental Mercury, GEM, and gaseous oxidized mercury, GOM), GOM and particulate-bound mercury (PBM) were monitored from November 2009 to November 2010 to investigate the characteristics and atmospheric transport of mercury influenced by the Indian summer monsoon (ISM) and westerlies. The mean concentrations of TGM, PBM and GOM were 2.55 ± 0.73 ng m−3, 37.78 ± 31.35 pg m−3 and 7.90 ± 7.89 ng m−3. A notable seasonal pattern was observed with higher TGM concentrations in the beginning and end of the ISM. High TGM concentrations were associated with the transport of dry air that carried regional anthropogenic emissions from both domestic and foreign sources. The low PBM and GOM level was attributed to the deposition and wet scavenging during the ISM period. Backward trajectory analysis of air masses associated with TGM levels suggested that both the ISM and westerlies can carry Hg emitted in Burma, Bengal bay and north India to the SAWRS.

scholarly journals Worldwide atmospheric mercury measurements: a review and synthesis of spatial and temporal trends

2010 ◽  
Vol 10 (1) ◽  
pp. 1261-1307 ◽  
Author(s):  
F. Sprovieri ◽  
N. Pirrone ◽  
R. Ebinghaus ◽  
H. Kock ◽  
A. Dommergue
Keyword(s):  
Temporal Trends ◽  
Ambient Air ◽  
Atmospheric Mercury ◽  
Water Soluble ◽  
Polar Regions ◽  
Mercury Emissions ◽  
Gaseous Mercury ◽  
National Programs ◽  
Spatial And Temporal Trends

Abstract. A large number of activities have been carried out during the last decade in different regions of the world, including polar regions, aiming to assess the level of mercury (Hg) species in ambient air and in precipitation observing their variation over time and with changing meteorological conditions. Following the discovery of atmospheric Hg depletion events (AMDEs) in Polar Regions several studies have indeed been conducted in order to assess the chemical-physical mechanisms related to AMDEs occurred in polar atmospheres with special attention to the consequences of these phenomena in terms of contamination of polar environment due to the rapid conversion of atmospheric gaseous Hg (Hg0) into reactive and water-soluble forms that may potentially become bioavailable. The understanding of the way in which mercury released to the atmosphere is eventually incorporated into biota is of crucial importance not only for the polar regions but also for the marine environment in general. The world's oceans and seas are in fact both sources and sinks of Hg and although it appears that the atmosphere is the major transport/distribution medium for Hg, because most Hg emissions are to the atmosphere, oceans and seas also play an important role. Currently, however, a coordinated observational network for Hg does not exist. There are a number of state and national programs that are collecting atmospheric Hg data but the parameters monitored, the locations of the monitoring sites and the methods employed may prohibit their utility in assessing Hg long-trend variations. The large increase in mercury emissions in fast developing countries (i.e., China, India) over the last decade due primarily to a sharp increase in energy production from the combustion of coal are not currently reflected in the long-term measurements of total gaseous mercury in ambient air and in precipitation data at several continuous monitoring sites in North Europe and North America. The discrepancy between observed gaseous mercury concentrations (steady or decreasing) and global mercury emission inventories (increasing) is not yet clear however, could be at least in part accounted by the increasing in the potential oxidation of the atmosphere recently documented. Therefore, measurements of other key atmospheric constituents at the global monitoring sites are necessary for us to develop a better understanding of the global redistribution of Hg and to further refine model parameterizations of the key processes. The sharing of data from this network, allowing, in fact, access to comparable and long-term data from a wide array of locations for understanding temporal and spatial patterns of Hg transport, deposition and re-emission process producing thus data that will support the validation of regional and global atmospheric Hg models. This paper presents a detailed overview of atmospheric mercury measurements conducted in the Northern and Southern Hemispheres at several terrestrial sites (industrial, rural and remote) during the last decade as well as measurements performed over the world's ocean and seas and in Polar Regions with reference to the monitoring techniques and location of monitoring sites in most of the continents.

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