Global Concentrations of Gaseous Elemental Mercury and Reactive Gaseous Mercury in the Marine Boundary Layer

2010 ◽  
Vol 44 (19) ◽  
pp. 7425-7430 ◽  
Author(s):  
Anne L. Soerensen ◽  
Henrik Skov ◽  
Daniel J. Jacob ◽  
Britt T. Soerensen ◽  
Matthew S. Johnson
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Elemental Mercury ◽  
Gaseous Elemental Mercury ◽  
Reactive Gaseous Mercury ◽  
Gaseous Mercury

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 High levels of reactive gaseous mercury observed at a high elevation research laboratory in the Rocky Mountains

2009 ◽  
Vol 9 (4) ◽  
pp. 15641-15671 ◽  
Author(s):  
X. Faïn ◽  
D. Obrist ◽  
A. G. Hallar ◽  
I. McCubbin ◽  
T. Rahn
Keyword(s):  
Relative Humidity ◽  
Elemental Mercury ◽  
High Elevation ◽  
Dominant Factor ◽  
Gaseous Elemental Mercury ◽  
Reactive Gaseous Mercury ◽  
Gaseous Mercury ◽  
Long Time ◽  
Chemical Cycling

Abstract. The chemical cycling and spatiotemporal distribution of mercury in the troposphere is poorly understood. We measured gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate mercury (HgP) along with CO, ozone, aerosols, and meteorological variables at Storm Peak Laboratory at an elevation of 3200 m a.s.l., in Colorado, from 28 April to 1 July 2008. The mean mercury concentrations were 1.6 ng m−3 (GEM), 20 pg m−3 (RGM) and 9 pg m−3 (HgP). We observed eight events of strongly enhanced atmospheric RGM levels with maximum concentrations up to 135 pg m−3. RGM enhancement events were unrelated to daytime/nighttime patterns and lasted for long time periods of 2 to 6 days. During seven of these events, RGM was inversely correlated to GEM (RGM/GEM regression slope ~ −0.1), but did not exhibit correlations with ozone, carbon monoxide, or aerosol concentrations. Relative humidity was the dominant factor affecting RGM levels with high RGM levels always present whenever relative humidity was below 40 to 50%. We conclude that RGM enhancements observed at Storm Peak Laboratory were not induced by pollution events and were related to oxidation of tropospheric GEM, but the mechanism remain unclear. Based on backtrajectory analysis and a lack of mass balance between RGM and GEM, we propose that in situ production of RGM may have occurred in some distance allowing for scavenging and/or deposition of some RGM prior to reaching the laboratory, and that GEM oxidation is an important tropospheric Hg sink. Our observations provide evidence that the tropospheric pool of mercury is frequently enriched in divalent mercury and that high RGM levels are not limited to the upper troposphere.

scholarly journals Two new sources of reactive gaseous mercury in the free troposphere

2012 ◽  
Vol 12 (11) ◽  
pp. 29203-29233 ◽  
Author(s):  
H. Timonen ◽  
J. L. Ambrose ◽  
D. A. Jaffe
Keyword(s):  
Source Region ◽  
Elemental Mercury ◽  
Anthropogenic Pollution ◽  
Atmospheric Mercury ◽  
Free Troposphere ◽  
Mercury Deposition ◽  
Gaseous Elemental Mercury ◽  
Reactive Gaseous Mercury ◽  
Gaseous Mercury ◽  
The Pacific

Abstract. Mercury (Hg) is a neurotoxin that bioaccumulates in the food chain. Mercury is emitted to the atmosphere primarily in its elemental form, which has a long lifetime allowing global transport. It is known that atmospheric oxidation of gaseous elemental mercury (GEM) generates reactive gaseous mercury (RGM) which plays an important role in the atmospheric mercury cycle by enhancing the rate of mercury deposition to ecosystems. However, the primary GEM oxidants, and the sources and chemical composition of RGM are poorly known. Using speciated mercury measurements conducted at the Mt. Bachelor Observatory since 2005 we present two previously unidentified sources of RGM to the free troposphere (FT). Firstly, we observed elevated RGM concentrations, large RGM/GEM-ratios, and anti-correlation between RGM and GEM during Asian long-rang transport events, demonstrating that RGM is formed from GEM by in-situ oxidation in some anthropogenic pollution plumes in the FT. During the Asian pollution events the measured RGM/GEM-ratios reached peak values, up to ~0.20, which are significantly larger than ratios typically measured (RGM/GEM < 0.05) in the Asian source region. Secondly, we observed very high RGM levels – the highest reported in the FT – in clean air masses that were processed upwind of Mt. Bachelor Observatory over the Pacific Ocean. The high RGM concentrations (up to 700 pg m−3), high RGM/GEM-ratios (up to 1), and very low ozone levels during these events provide the first observational evidence indicating significant GEM oxidation in the lower FT. The identification of these processes changes our conceptual understanding of the formation and distribution of oxidized Hg in the global atmosphere.

scholarly journals High levels of reactive gaseous mercury observed at a high elevation research laboratory in the Rocky Mountains

2009 ◽  
Vol 9 (20) ◽  
pp. 8049-8060 ◽  
Author(s):  
X. Faïn ◽  
D. Obrist ◽  
A. G. Hallar ◽  
I. Mccubbin ◽  
T. Rahn
Keyword(s):  
Boundary Layer ◽  
Carbon Monoxide ◽  
Relative Humidity ◽  
Vertical Mixing ◽  
Elemental Mercury ◽  
High Elevation ◽  
Dominant Factor ◽  
Air Masses ◽  
Reactive Gaseous Mercury ◽  
Gaseous Mercury

Abstract. The chemical cycling and spatiotemporal distribution of mercury in the troposphere is poorly understood. We measured gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate mercury (HgP) along with carbon monoxide (CO), ozone (O3), aerosols, and meteorological variables at Storm Peak Laboratory at an elevation of 3200 m a.s.l., in Colorado, from 28 April to 1 July 2008. The mean mercury concentrations were 1.6 ng m−3 (GEM), 20 pg m−3 (RGM) and 9 pg m−3 (HgP). We observed eight events of strongly enhanced atmospheric RGM levels with maximum concentrations up to 137 pg m−3. RGM enhancement events lasted for long time periods of 2 to 6 days showing both enriched level during daytime and nighttime when other tracers (e.g., aerosols) showed different representations of boundary layer air and free tropospheric air. During seven of these events, RGM was inversely correlated to GEM (RGM/GEM regression slope ~−0.1), but did not exhibit correlations with ozone, carbon monoxide, or aerosol concentrations. Relative humidity was the dominant factor affecting RGM levels with high RGM levels always present whenever relative humidity was below 40 to 50%. We conclude that RGM enhancements observed at Storm Peak Laboratory were not induced by pollution events and were related to oxidation of tropospheric GEM. High RGM levels were not limited to upper tropospheric or stratospherically influenced air masses, indicating that entrainment processes and deep vertical mixing of free tropospheric air enriched in RGM may lead to high RGM levels throughout the troposphere and into the boundary layer over the Western United States. Based on backtrajectory analysis and a lack of mass balance between RGM and GEM, atmospheric production of RGM may also have occurred in some distance allowing for scavenging and/or deposition of RGM prior to reaching the laboratory. Our observations provide evidence that the tropospheric pool of mercury is frequently enriched in divalent mercury, that high RGM levels are not limited to upper tropospheric air masses, but that the build-up of high RGM in the troposphere is limited to the presence of dry air.

Sign in / Sign up

Export Citation Format

Share Document