Photochemical Formation of volatile mercury in high Arctic lakes

Amyot, Marc; Lean, D. R. S.; Mierle, Greg

doi:10.1002/etc.5620161010

Cited by 86 publications

(57 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[52][53][54] Arctic lakes generally contain supersaturated surface water concentrations of DGM. [55,56] The latter studies reported average DGM concentrations of the order of 200 fM (40 pg L À1 ), representing ,3 % of the total dissolved Hg in lake waters. In Arctic Alaskan lakes, the DGM evasion flux was similar to the atmospheric input of Hg in summer precipitation [56] but dry deposition of Hg species was not included in this budget.…”

Section: Since 1993 Prof Henrik Skov Has Worked As Principal Scientimentioning

confidence: 98%

“…The rate is controlled by: the intensity of solar radiation, particularly the UV-B (280-320 nm) and UV-A (320-400 nm) wavebands, and the concentration of available photo-reducible Hg II complexes. [55] A model for Hg 0 with depth in the water column incorporating photoreduction, photooxidation, bioreduction and biooxidation was recently developed. [60] The model results suggest that because of: (i) light energy attenuation with depth and (ii) the presence of chloride, biologically mediated processes are likely to dominate the production of Hg 0 .…”

Section: Since 1993 Prof Henrik Skov Has Worked As Principal Scientimentioning

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

119

147

View full text Add to dashboard Cite

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.

show abstract

Section: Since 1993 Prof Henrik Skov Has Worked As Principal Scientimentioning

confidence: 98%

Section: Since 1993 Prof Henrik Skov Has Worked As Principal Scientimentioning

confidence: 99%

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

Douglas

Loseto²,

Macdonald³

et al. 2012

Environ. Chem.

Self Cite

119

147

View full text Add to dashboard Cite

show abstract

“…Photochemically induced Hg II reduction is the predominant pathway of DGM formation in surface water (Amyot et al, 1994(Amyot et al, , 1997aCosta and Liss, 1999;Lalonde et al, 2001;Feng et al, 2004). Zhang (2006) summarized the Hg photochemical redox chemical process.…”

Section: Air-water Hg Exchangementioning

confidence: 99%

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

et al. 2016

View full text Add to dashboard Cite

Abstract. Reliable quantification of air-surface fluxes of elemental Hg vapor (Hg 0 ) is crucial for understanding mercury (Hg) global biogeochemical cycles. There have been extensive measurements and modeling efforts devoted to estimating the exchange fluxes between the atmosphere and various surfaces (e.g., soil, canopies, water, snow, etc.) in the past three decades. However, large uncertainties remain due to the complexity of Hg 0 bidirectional exchange, limitations of flux quantification techniques and challenges in model parameterization. In this study, we provide a critical review on the state of science in the atmosphere-surface exchange of Hg 0 . Specifically, the advancement of flux quantification techniques, mechanisms in driving the air-surface Hg exchange and modeling efforts are presented. Due to the semi-volatile nature of Hg 0 and redox transformation of Hg in environmental media, Hg deposition and evasion are influenced by multiple environmental variables including seasonality, vegetative coverage and its life cycle, temperature, light, moisture, atmospheric turbulence and the presence of reactants (e.g., O 3 , radicals, etc.). However, the effects of these processes on flux have not been fundamentally and quantitatively determined, which limits the accuracy of flux modeling.We compile an up-to-date global observational flux database and discuss the implication of flux data on the global Hg budget. Mean Hg 0 fluxes obtained by micrometeorological measurements do not appear to be significantly greater than the fluxes measured by dynamic flux chamber methods over unpolluted surfaces (p = 0.16, one-tailed, Mann-Whitney U test). The spatiotemporal coverage of existing Hg 0 flux measurements is highly heterogeneous with large data gaps existing in multiple continents (Africa, South Asia, Middle East, South America and Australia). The magnitude of the evasion flux is strongly enhanced by human activities, particularly at contaminated sites. Hg 0 flux observations in East Asia are comparatively larger in magnitude than the rest of the world, suggesting substantial re-emission of previously deposited mercury from anthropogenic sources. The Hg 0 exchange over pristine surfaces (e.g., background soil and water) and vegetation needs better constraints for global analyses of the atmospheric Hg budget. The existing knowledge gap and the associated research needs for future measurements and modeling efforts for the air-surface exchange of Hg 0 are discussed.

show abstract

“…During such incubations, some samples are wrapped in various light filters, or kept in the dark, in order to isolate the effect of different wavebands (UV-A, UV-B, visible). Samples are occasionally spiked with reactive oxy-gen species (Amyot et al, 1997), dissolved organic carbon (Amyot et al, 1997); humic acids (Costa and Liss, 2000) or other compounds potentially involved in photoreduction reactions such as Fe(III) (Zhang and Lindberg, 2001). Photoreduction and photooxidation are known to occur simultaneously.…”

Section: Photoreduction and Photooxidation In Fresh And Sea Watermentioning

confidence: 99%

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

Steffen

Douglas

Amyot³

et al. 2008

Atmos. Chem. Phys.

436

439

View full text Add to dashboard Cite

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 Correspondence to: A. Steffen (alexandra.steffen@ec.gc.ca) 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 Published by Copernicus Publications on behalf of the European Geosciences Union. 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 envir...

show abstract

Photochemical Formation of volatile mercury in high Arctic lakes

Cited by 86 publications

References 40 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

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

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

Contact Info

Product

Resources

About