Effect of temperature and air movement on the flux of elemental mercury from substrate to the atmosphere

Gustin, Mae Sexauer; Taylor, George; Maxey, Rachel A.

doi:10.1029/96jd02742

Cited by 132 publications

(105 citation statements)

References 32 publications

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“…Figure 1 (middle panels) shows the total Hg emission from both anthropogenic and natural sources. Geogenic Hg emissions in the model are a significant source in western North America along a band stretching from southwest Canada to Mexico (Gustin et al, 1997). The modeled re-emissions from soil, snow and ocean generally follow the spatial pattern of anthropogenic emissions.…”

Section: Nested-grid Hg Simulationmentioning

confidence: 99%

Nested-grid simulation of mercury over North America

et al. 2012

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Abstract. We have developed a new nested-grid mercury (Hg) simulation over North America with a 1/2 • latitude by 2/3 • longitude horizontal resolution employing the GEOSChem global chemical transport model. Emissions, chemistry, deposition, and meteorology are self-consistent between the global and nested domains. Compared to the global model (4 • latitude by 5 • longitude), the nested model shows improved skill at capturing the high spatial and temporal variability of Hg wet deposition over North America observed by the Mercury Deposition Network (MDN) in [2008][2009]. The nested simulation resolves features such as higher deposition due to orographic precipitation, land/ocean contrast and and predicts more efficient convective rain scavenging of Hg over the southeast United States. However, the nested model overestimates Hg wet deposition over the Ohio River Valley region (ORV) by 27 %. We modify anthropogenic emission speciation profiles in the US EPA National Emission Inventory (NEI) to account for the rapid inplume reduction of reactive to elemental Hg (IPR simulation). This leads to a decrease in the model bias to −2.3 % over the ORV region. Over the contiguous US, the correlation coefficient (r) between MDN observations and our IPR simulation increases from 0.60 to 0.78. The IPR nested simulation generally reproduces the seasonal cycle in surface concentrations of speciated Hg from the Atmospheric Mercury Network (AMNet) and Canadian Atmospheric Mercury Network (CAMNet). In the IPR simulation, annual mean gaseous and particulate-bound Hg(II) are within 140 % and 11 % of observations, respectively. In contrast, the simulation with unmodified anthropogenic Hg speciation profiles overestimates these observations by factors of 4 and 2 for gaseous and particulate-bound Hg(II), respectively. The nested model shows improved skill at capturing the horizontal variability of Hg observed over California during the ARCTAS aircraft campaign. The nested model suggests that North American anthropogenic emissions account for 10-22 % of Hg wet deposition flux over the US, depending on the anthropogenic emissions speciation profile assumed. The modeled percent contribution can be as high as 60 % near large point sources in ORV. Our results indicate that the North American anthropogenic contribution to dry deposition is 13-20 %.

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Section: Nested-grid Hg Simulationmentioning

confidence: 99%

Nested-grid simulation of mercury over North America

et al. 2012

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“…Factors that have been identified as controls on GEM surface exchange in the literature include soil moisture (Gustin et al, 2006), precipitation (Song and Van Heyst, 2005), radiation (Carpi and Lindberg, 1997;Choi and Holsen, 2009), temperature (Gustin et al, 1997;Choi and Holsen, 2009), vegetation (Hanson et al, 1995;Stamenkovic and Gustin, 2009) and GEM/oxidant concentrations (Engle et al, 2005;Zhang et al, 2008). Linear correlations between GEM fluxes and environmental data were generally weak ( Table 1).…”

Section: Environmental Correlatesmentioning

confidence: 99%

Mercury fluxes over an Australian alpine grassland and observation of nocturnal atmospheric mercury depletion events

Howard

Edwards

2018

Atmos. Chem. Phys.

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Abstract. Aerodynamic gradient measurements of the airsurface exchange of gaseous elemental mercury (GEM) were undertaken over a 40 ha alpine grassland in Australia's Snowy Mountains region across a 3-week period during the late austral summer. Bi-directional GEM fluxes were observed throughout the study, with overall mean value of 0.2 ± 14.5 ng m −2 h −1 and mean nocturnal fluxes of −1.5 ± 7.8 ng m −2 h −1 compared to diurnal fluxes of 1.8 ± 18.6 ng m −2 h −1 . Deposition velocities ranged from −2.2 to 2.9 cm s −1 , whilst ambient GEM concentrations throughout the study were 0.59 ± 0.10 ng m −3 . Cumulative GEM fluxes correlated well with 24 h running mean soil temperatures, and one precipitation event was shown to have a positive impact on diurnal emission fluxes. The underlying vegetation had largely senesced and showed little stomatal control on fluxes. Nocturnal atmospheric mercury depletion events (NAMDEs) were observed concomitant with O 3 depletion and dew formation under shallow, stable nocturnal boundary layers. A mass balance box model was able to reproduce ambient GEM concentration patterns during NAMDE and non-NAMDE nights without invoking chemical oxidation of GEM throughout the column, indicating a significant role of surface processes controlling deposition in these events. Surface deposition was enhanced under NAMDE nights, though uptake to dew likely represents less than one-fifth of this enhanced deposition. Instead, enhancement of the surface GEM gradient as a result of oxidation at the surface in the presence of dew is hypothesised to be responsible for a large portion of GEM depletion during these particular events. GEM emission pulses following nights with significant deposition provide evidence for the prompt recycling of 17 % of deposited mercury, with the remaining portion retained in surface sinks. The long-term impacts of any sinks are however likely to be minimal, as cumulative GEM flux across the study period was close to zero.

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“…As duas primeiras etapas são fortemente influenciadas pelas características físico-químicas do solo e a última, é bastante influenciada pelas condições meteorológicas 41 . Vários estudos da literatura demonstram forte influência dos parâmetros meteorológicos sobre as emissões de Hg, entre eles, temperatura do solo e do ar, radiação solar e umidade relativa do ar 8,28,29,42,43 .…”

Section: Fluxos De Mgt Na Interface Solo/atmosferaunclassified

“…Isto explicaria inclusive a variação nictemeral e sazonal da emissão de Hg pelos solos 28,41,42 . A elevação da temperatura pode causar também um aumento da atividade microbiológica, que resultaria numa intensificação da formação de espécies voláteis de Hg 42 .…”

Section: Fluxos De Mgt Na Interface Solo/atmosferaunclassified

“…Em estudos recentes, a intensidade e a natureza das radiações solares, assim como a temperatura do solo, foram indicadas como fatores determinantes no aumento das emissões de mercúrio dos solos para a atmosfera 8,11,13,[24][25][26][27][28][29] . A variação da umidade do solo, por sua vez, parece apresentar tanto uma influência positiva quanto negativa sobre as emissões de Hg, dependendo do grau de saturação do solo 11 .…”

Section: Introductionunclassified

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Quantificação de fluxos de mercúrio gasoso na interface solo/atmosfera utilizando câmara de fluxo dinâmica: aplicação na bacia do Rio Negro

Magarelli¹,

Fostier²

2005

Quím. Nova

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Recebido em 1/7/04; aceito em 28/3/05; publicado na web em 10/8/05QUANTIFICATION OF ATMOSPHERE -SOIL MERCURY FLUXES BY USING A DYNAMIC FLUX CHAMBER: APPLICATION AT THE NEGRO RIVER BASIN, AMAZON. Gaseous mercury sampling conditions were optimized and a dynamic flux chamber was used to measure the air/surface exchange of mercury in some areas of the Negro river basin with different vegetal coverings. At the two forest sites (flooding and non-flooding), low mercury fluxes were observed: maximum of 3 pmol m -2 h -1 -day and minimum of -1 pmol m -2 h -1 -night. At the deforested site, the mercury fluxes were higher and always positive: maximum of 26 pmol m -2 h -1 -day and 17 pmol m -2 h -1 -night. Our results showed that deforestation could be responsible for significantly increasing soil Hg emissions, mainly because of the high soil temperatures reached at deforested sites.Keywords: mercury fluxes; atmosphere-soil exchange; flux chamber. INTRODUÇÃOUma das características mais marcantes do Hg em relação a outros metais é sua capacidade de ser emitido ou reemitido para a atmosfera, principalmente na sua forma gasosa elementar (Hg 0 ). Devido a algumas de suas propriedades tais como baixa reatividade e baixa solubilidade em água, o Hg 0 apresenta um tempo de residência na atmosfera da ordem de um ano, facilitando sua distribuição e deposição numa escala global, razão pela qual foi desenvolvido o conceito de "poluente global" para esse elemento 1 . Na atmosfera, o Hg pode participar de vários processos e/ou interações de natureza química, física ou fotoquímica, propiciando sua transferência para os compartimentos aquáticos e terrestres, bem como sua possível conversão a metil-mercúrio (MeHg) 2 . A propriedade do MeHg de ser bio-acumulado em até um milhão de vezes ao longo da cadeia alimentar em meio aquático constitui uma das principais preocupações ambientais da ecotoxicologia do mercúrio, justificando o estudo do seu ciclo biogeoquímico e, em particular, dos processos de transferência desse elemento entre os diferentes compartimentos 1,2 .O "Expert Panel" 3 estimou que aproximadamente 95% das 200.000 t de Hg mobilizados desde 1890 acumulam-se atualmente nos solos superficiais. A reemissão de uma parcela desse estoque seria equivalente ao total das emissões antrópicas dos Estados Unidos 4 . As florestas cobrem aproximadamente 4x10 9 ha da superfície terrestre, e o destino do Hg estocado, seja no solo, seja na vegetação, é ainda amplamente desconhecido. Considerando que a Amazônia brasileira é coberta por 0,4x10 9 ha de floresta 5 , ou seja, 10% da área coberta por florestas no planeta, justifica-se a importância de se estudar os processos de transferência do Hg nesse ecossistema. Esta necessidade aumenta se for considerada a pequena quantidade de dados já obtidos em áreas de florestas tropicais úmidas, sendo que a maioria dos dados disponíveis são relativos a florestas temperadas e boreais 2,6,7 .Vários estudos já foram realizados com o objetivo de medir in situ as taxas de emissão ou de deposição do mercúrio gasoso t...

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Effect of temperature and air movement on the flux of elemental mercury from substrate to the atmosphere

Cited by 132 publications

References 32 publications

Nested-grid simulation of mercury over North America

Nested-grid simulation of mercury over North America

Mercury fluxes over an Australian alpine grassland and observation of nocturnal atmospheric mercury depletion events

Quantificação de fluxos de mercúrio gasoso na interface solo/atmosfera utilizando câmara de fluxo dinâmica: aplicação na bacia do Rio Negro

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