Investigation of the deposition and emission of mercury in arctic snow during an atmospheric mercury depletion event

Johnson, Kelsey P.; Blum, Joel D.; Keeler, Gerald J.; Douglas, Thomas A.

doi:10.1029/2008jd009893

Cited by 71 publications

(114 citation statements)

References 43 publications

(58 reference statements)

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“…[245] In contrast, it is now well established that the Hg deposited during AMDEs can be readily re-emitted from the snowpack during winter conditions following AMDEs [7,16,25,80,101,187,241,[246][247][248] and during snow metamorphism and melt. [20,79] Establishing a link between AMDEs and enhanced Hg levels in Arctic biota is complicated partly by a poor understanding of the net outcome of the AMDE deposition pathway, and partly by the complex Hg biogeochemistry of aquatic marine and fresh water ecosystems that contain inorganic Hg II from a variety of sources (of which AMDEs are but one) and methylate the inorganic Hg II into MeHg.…”

Section: Eastern Beaufort Sea Belugamentioning

confidence: 99%

“…[252] Results from many Arctic locations suggest that 60-80 % of total deposited Hg is photo-reduced to volatile Hg 0 and re-emitted back to the atmosphere within days of AMDEs. [7,80,101,187,241,247,248] Fig. 10 includes a summary of the results from 10 different studies [247] that monitored the THg concentration in snow with time since an AMDE was active.…”

Section: Eastern Beaufort Sea Belugamentioning

confidence: 99%

“…Resolute, Canada (Poulain et al [293] ) Alert, Canada (St Louis et al [218] ) Barrow, Alaska (Johnson et al [248] ) to be particularly strong in the northernmost area. [258,259] This pattern is not due to higher wet deposition along the coast.…”

Section: Eastern Beaufort Sea Belugamentioning

confidence: 99%

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The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

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123

147

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Environmental context. Mercury, in its methylated form, is a neurotoxin that biomagnifies in marine and terrestrial foodwebs leading to elevated levels in fish and fish-eating mammals worldwide, including at numerous Arctic locations. Elevated mercury concentrations in Arctic country foods present a significant exposure risk to Arctic people. We present a detailed review of the fate of mercury in Arctic terrestrial and marine ecosystems, taking into account the extreme seasonality of Arctic ecosystems and the unique processes associated with sea ice and Arctic hydrology.Abstract. This review is the result of a series of multidisciplinary meetings organised by the Arctic Monitoring and Assessment Programme as part of their 2011 Assessment 'Mercury in the Arctic'. This paper presents the state-of-the-art knowledge on the environmental fate of mercury following its entry into the Arctic by oceanic, atmospheric and terrestrial pathways. Our focus is on the movement, transformation and bioaccumulation of Hg in aquatic (marine and fresh water) and terrestrial ecosystems. The processes most relevant to biological Hg uptake and the potential risk associated with Hg exposure in wildlife are emphasised. We present discussions of the chemical transformations of newly deposited or transported Hg in marine, fresh water and terrestrial environments and of the movement of Hg from air, soil and water environmental compartments into food webs. Methylation, a key process controlling the fate of Hg in most ecosystems, and the role of trophic processes in controlling Hg in higher order animals are also included. Case studies on Eastern Beaufort Sea beluga (Delphinapterus leucas) and landlocked Arctic char (Salvelinus alpinus) are presented as examples of the relationship between ecosystem trophic processes and biologic Hg levels. We examine whether atmospheric mercury depletion events (AMDEs) contribute to increased Hg levels in Arctic biota and provide information on the links between organic carbon and Hg speciation, dynamics and bioavailability. Long-term sequestration of Hg into non-biological archives is also addressed. The review concludes by identifying major knowledge gaps in our understanding, including:(1) the rates of Hg entry into marine and terrestrial ecosystems and the rates of inorganic and MeHg uptake by Arctic microbial and algal communities; (2) the bioavailable fraction of AMDE-related Hg and its rate of accumulation by biota and (3) the fresh water and marine MeHg cycle in the Arctic, especially the marine MeHg cycle.

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Section: Eastern Beaufort Sea Belugamentioning

confidence: 99%

Section: Eastern Beaufort Sea Belugamentioning

confidence: 99%

See 1 more Smart Citation

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

Self Cite

123

147

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“…In the frozen upper portions of deep convective clouds, the scavenging and removal of soluble gas also depends on whether dissolved gas stays in solution when liquid drops freeze onto hail or graupel, as HNO 3 does (Barth et al, 2001(Barth et al, , 2007Yin et al, 2001). GOM observations in high-altitude clouds are not available, but surface observations of GOM during riming and snowfall conditions suggest that dissolved GOM is also retained during freezing, but not scavenged from gas by ice Johnson et al, 2008;Sigler et al, 2009). Particle-bound mercury is found on polluted urban, sulfate and sea salt aerosols (Murphy et al, 2006;Feddersen et al, 2012) and thus behaves similarly to other hydrophilic aerosols inside clouds.…”

Section: Introductionmentioning

confidence: 99%

Cloud-resolving simulations of mercury scavenging and deposition in thunderstorms

Nair

Holmes

et al. 2013

Atmos. Chem. Phys.

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Abstract. This study examines dynamical and microphysical features of convective clouds that affect mercury (Hg) wet scavenging and concentrations in rainfall. Using idealized numerical model simulations in the Regional Atmospheric Modeling System (RAMS), we diagnose vertical transport and scavenging of soluble Hg species -gaseous oxidized mercury (GOM) and particle-bound mercury (HgP), collectively Hg(II) -in thunderstorms under typical environmental conditions found in the Northeast and Southeast United States (US). Mercury scavenging efficiencies from various initial altitudes are diagnosed for a case study of a typical strong convective storm in the Southeast US. Assuming that soluble mercury concentrations are initially vertically uniform, the model results suggest that 60 % of mercury deposited to the surface in rainwater originates from above the boundary layer (> 2 km). The free troposphere could supply a larger fraction of mercury wet deposition if GOM and HgP concentrations increase with altitude. We use radiosonde observations in the Northeast and Southeast to characterize three important environmental characteristics that influence thunderstorm morphology: convective available potential energy (CAPE), vertical shear (0-6 km) of horizontal wind (SHEAR) and precipitable water (PW). The Southeast US generally has lower SHEAR and higher CAPE and PW. We then use RAMS to test how PW and SHEAR impact mercury scavenging and deposition, while keeping the initial Hg(II) concentrations fixed in all experiments. We found that the mercury concentration in rainfall is sensitive to SHEAR with the nature of sensitivity differing depending upon the PW. Since CAPE and PW cannot be perturbed independently, we test their combined influence using an ensemble of thunderstorm simulations initialized with environmental conditions for the Northeast and Southeast US. These simulations, which begin with identical Hg(II) concentrations, predict higher mercury concentrations in rainfall from thunderstorms forming in the environmental conditions over the Southeast US compared to the Northeast US. A final simulation of a stratiform rain event produces lower mercury concentrations than in thunderstorms forming in environments typical of the Southeast US. The stratiform cloud scavenges mercury from the lowest ∼ 4 km of the atmosphere, while thunderstorms scavenge up to ∼ 10 km.

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“…Reduction is primarily through photoreduction by UV-B radiation in the 305-320 nm wavelength range (Lalonde et al, 2003;Poulain et al, 2004;St. Louis et al, 2005;Dommergue et al, 2007;Faïn et al, 2007;Johnson et al, 2008;Sherman et al, 2010). Prior to revolatilization, the produced GEM may be reoxidized (Lalonde et al, 2003;Ferrari et al, 2004b;Poulain et al, 2004Poulain et al, , 2007bMann et al, 2005;Lahoutifard et al, 2006;Lin et al, 2006;Dommergue et al, 2007;Faïn et al, 2006Faïn et al, , 2007Faïn et al, , 2008.…”

Section: Introductionmentioning

confidence: 99%

How relevant is the deposition of mercury onto snowpacks? – Part 2: A modeling study

Durnford¹,

Dastoor

Ryzhkov

et al. 2012

Atmos. Chem. Phys.

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Abstract. An unknown fraction of mercury that is deposited onto snowpacks is revolatilized to the atmosphere. Determining the revolatilized fraction is important since mercury that enters the snowpack meltwater may be converted to highly toxic bioaccumulating methylmercury. In this study, we present a new dynamic physically-based snowpack/meltwater model for mercury that is suitable for large-scale atmospheric models for mercury. It represents the primary physical and chemical processes that determine the fate of mercury deposited onto snowpacks. The snowpack/meltwater model was implemented in Environment Canada's atmospheric mercury model GRAHM. For the first time, observed snowpack-related mercury concentrations are used to evaluate and constrain an atmospheric mercury model. We find that simulated concentrations of mercury in both snowpacks and the atmosphere's surface layer agree closely with observations. The simulated concentration of mercury in both in the top 30 cm and the top 150 cm of the snowpack, averaged over 2005-2009, is predominantly below 6 ng L −1 over land south of 66.5°N but exceeds 18 ng L −1 over sea ice in extensive areas of the Arctic Ocean and Hudson Bay. The average simulated concentration of mercury in snowpack meltwater runoff tends to be higher on the Russian/European side (>20 ng L −1 ) of the Arctic Ocean than on the Canadian side (<10 ng L −1 ). The correlation coefficient between observed and simulated monthly mean atmospheric surface-level gaseous elemental mercury (GEM) concentrations increased significantly with the inclusion of the new snowpack/meltwater model at two of the three stations (midlatitude, subarctic) studied and remained constant at the third (arctic). Oceanic emissions are postulated to produce the observed summertime maximum in concentrations of surface-level atmospheric GEM at Alert in the Canadian Arctic and to generate the summertime volatility observed in these concentrations at both Alert and Kuujjuarapik on subarctic Hudson Bay, Canada. We find that the fraction of deposited mercury that is revolatilized from snowpacks increases with latitude from 39 % between 30 and 45°N, to 57 % from 45 to 60°N, 67 % from 60 to 66.5°N, and 75 % polewards of 66.5°N on an annual basis. Combining this latitudinal gradient with the latitudinally increasing coverage of snowpacks causes yearly net deposition as a fraction of gross deposition to decrease from 98 % between 30 and 45°N to 89 % between 45 and 60°N, 73 % between 60 and 66.5°N, and 44 % within the Arctic Circle. The yearly net deposition and net accumulation of mercury at the surface within the Arctic Circle north of 66.5°N are estimated at 153 and 117 Mg, respectively. We calculate that 58 and 50 Mg of mercury are deposited annually to the Arctic Ocean directly and indirectly via melting snowpacks, respectively. For terrestrial surfaces within the Arctic Circle, we find that 29 and 16 Mg of mercury are deposited annually directly and indirectly via melting snowpacks, respectively. Within the Arctic Circle, multi-s...

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Investigation of the deposition and emission of mercury in arctic snow during an atmospheric mercury depletion event

Cited by 71 publications

References 43 publications

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

Cloud-resolving simulations of mercury scavenging and deposition in thunderstorms

How relevant is the deposition of mercury onto snowpacks? – Part 2: A modeling study

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