Exchange of Elemental Mercury between the Oceans and the Atmosphere

Qureshi, Asif H.; MacLeod, Matthew; Sunderland, Elsie M.; Hungerbühler, Konrad

doi:10.1002/9781118146644.ch12

Cited by 15 publications

(23 citation statements)

References 67 publications

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“…3) (Kim and Fitzgerald, 1986). Surface wind speed is an important driving force enhancing the mass transfer coefficient in water (Qureshi et al, 2011b), D Hg 0 has been experimentally determined as a function of temperature (T , Kelvin) for freshwater (D fresh Hg 0 = 0.0335e −18.63/RT , R represents gas constant) and seawater (D sea Hg 0 = 0.0011e −11.06/RT ) (Kuss, 2014).…”

Section: Air-water Hg Exchangementioning

confidence: 99%

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

et al. 2016

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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.

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Section: Air-water Hg Exchangementioning

confidence: 99%

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

et al. 2016

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“…Globally, atmospheric deposition is the dominant Hg input to the ocean (Mason and Sheu, 2002;Selin, 2009). In seawater Hg can reduce to Hg(0) via photochemistry and microbial activities (Amyot et al, 1997;Rolfhus and Fitzgerald, 2004;Fantozzi et al, 2009;Qureshi et al, 2010;Whalin et al, 2007;Monperrus et al, 2007) from sea surface to atmosphere (Fitzgerald et al, 1984;Kuss and Schneider, 2007;Fu et al, 2010;Andersson et al, 2011;Ci et al, 2011a;Qureshi et al, 2012). Modeling studies showed that more than 80% of Hg deposited to oceans is reemitted to atmosphere as Hg(0) (e.g., Strode et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Elemental mercury (Hg(0)) in air and surface waters of the Yellow Sea during late spring and late fall 2012: Concentration, spatial-temporal distribution and air/sea flux

Wang

et al. 2015

Chemosphere

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“…Studies suggest that the reduction of divalent Hg (Hg(II)) to elemental Hg (Hg(0)) and oxidation of Hg(0) to Hg(II) (i.e., Hg redox chemistry) in waters can occur simultaneously and is regulated by both photochemical process and microbial process and the photoreduction of Hg(II) is the primary pathway for the production of Hg(0) (Amyot et al 1997;Lanzillotta et al 2002;Rolfhus and Fitzgerald 2004;Whalin et al 2007;Qureshi et al 2010;Ci et al 2016). Factors influencing the Hg redox chemistry in the marine environment include the Hg concentration and speciation in water, the strength and spectrum of solar radiation, the concentration and structure of dissolved organic matter and suspended particulate matter, salinity, biological activity, and so on (Qureshi et al 2012;Ci et al 2016). Field observations showed that water Hg(0) concentrations in waters of oceans and seas were highly variable both spatially and temporally, and surface waters were supersaturated with Hg(0) compared to air in most study time and regions (Qureshi et al 2012 and references therein).…”

Section: Introductionmentioning

confidence: 99%

“…Factors influencing the Hg redox chemistry in the marine environment include the Hg concentration and speciation in water, the strength and spectrum of solar radiation, the concentration and structure of dissolved organic matter and suspended particulate matter, salinity, biological activity, and so on (Qureshi et al 2012;Ci et al 2016). Field observations showed that water Hg(0) concentrations in waters of oceans and seas were highly variable both spatially and temporally, and surface waters were supersaturated with Hg(0) compared to air in most study time and regions (Qureshi et al 2012 and references therein).…”

Section: Introductionmentioning

confidence: 99%

Air–sea exchange of gaseous mercury in the tropical coast (Luhuitou fringing reef) of the South China Sea, the Hainan Island, China

Zhang

Wang

2016

Environ Sci Pollut Res

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The air-sea exchange of gaseous mercury (mainly Hg(0)) in the tropical ocean is an important part of the global Hg biogeochemical cycle, but the related investigations are limited. In this study, we simultaneously measured Hg(0) concentrations in surface waters and overlaying air in the tropical coast (Luhuitou fringing reef) of the South China Sea (SCS), Hainan Island, China, for 13 days on January-February 2015. The purpose of this study was to explore the temporal variation of Hg(0) concentrations in air and surface waters, estimate the air-sea Hg(0) flux, and reveal their influencing factors in the tropical coastal environment. The mean concentrations (±SD) of Hg(0) in air and total Hg (THg) in waters were 2.34 ± 0.26 ng m −3 and 1.40 ± 0.48 ng L −1 , respectively. Both Hg(0) concentrations in waters (53.7 ± 18.8 pg L −1 ) and Hg(0)/THg ratios (3.8 %) in this study were significantly higher than those of the open water of the SCS in winter. Hg(0) in waters usually exhibited a clear diurnal variation with increased concentrations in daytime and decreased concentrations in nighttime, especially in cloudless days with low wind speed. Linear regression analysis suggested that Hg(0) concentrations in waters were positively and significantly correlated to the photosynthetically active radiation (PAR) (R 2 = 0.42, p < 0.001). Surface waters were always supersaturated with Hg(0) compared to air (the degree of saturation, 2.46 to 13.87), indicating that the surface water was one of the atmospheric Hg(0) sources. The air-sea Hg(0) fluxes were estimated to be 1.73 ± 1.25 ng m −2 h −1 with a large range between 0.01 and 6.06 ng m −2 h −1 . The high variation of Hg(0) fluxes was mainly attributed to the greatly temporal variation of wind speed.

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Exchange of Elemental Mercury between the Oceans and the Atmosphere

Cited by 15 publications

References 67 publications

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

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

Elemental mercury (Hg(0)) in air and surface waters of the Yellow Sea during late spring and late fall 2012: Concentration, spatial-temporal distribution and air/sea flux

Air–sea exchange of gaseous mercury in the tropical coast (Luhuitou fringing reef) of the South China Sea, the Hainan Island, China

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