Water-air and soil-air exchange rate of total gaseous mercury measured at background sites

Poissant, Laurier; Casimir, A.

doi:10.1016/s1352-2310(97)00132-5

Cited by 261 publications

(204 citation statements)

References 16 publications

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“…However, this phenomenon needs further investigation by measuring the soil flux of mercury and its interaction with TGM in urban sectors of Beijing during warm periods. Measuring the water-air and soilair exchange rate of TGM in the summer of 1995 in the southern part of Quebec, Canada, Poissant and Casimir (1998) found that mercury flux from a grass covered soil was relatively constant ($2-3 ng/m 2 h) in the temperature range of 10-20°C. In the temperature range of 20-30°C mercury flux rose to $7-8 ng/m 2 h. They also found that mercury flux was positively correlated with wind speed (r 2 ¼ 0:3906).…”

Section: Diurnal Changes In Atmospheric Mercury Concentrationsmentioning

confidence: 99%

“…The relative flux parameter (F ) was measured using the modified version of a mass balance equation used by Poissant and Casimir (1998) for computation of mercury flux with the dynamic flux chamber technique. If site 6 was considered as a mercury receptor, the relative flux parameter (F ) measuring the mercury flux in all directions could be written as…”

Section: Effect Of Wind Frequencies On Atmospheric Mercury Fluxmentioning

confidence: 99%

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Atmospheric mercury monitoring survey in Beijing, China

et al. 2002

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With the aid of one industrial, two urban, two suburban, and two rural sampling locations, diurnal patterns of total gaseous mercury (TGM) were monitored in January, February and September of 1998 in Beijing, China. Monitoring was conducted in six (two urban, two suburban, one rural and the industrial sites) of the seven sampling sites during January and February (winter) and in four (two urban, one rural, and the industrial sites) of the sampling locations during September (summer) of 1998. In the three suburban sampling stations, mean TGM concentrations during the winter sampling period were 8.6, 10.7, and 6.2 ng/m 3 , respectively. In the two urban sampling locations mean TGM concentrations during winter and summer sampling periods were 24.7, 8.3, 10, and 12.7 ng/m 3 , respectively. In the suburban-industrial and the two rural sampling locations, mean mercury concentrations ranged from 3.1-5.3 ng/m 3 in winter to 4.1-7.7 ng/m 3 in summer sampling periods. In the Tiananmen Square (urban), and Shijingshan (suburban) sampling locations the mean TGM concentrations during the summer sampling period were higher than winter concentrations, which may have been caused by evaporation of soil-bound mercury in warm periods. Continuous meteorological data were available at one of the suburban sites, which allowed the observation of mercury concentration variations associated with some weather parameters. It was found that there was a moderate negative correlation between the wind speed and the TGM concentration at this suburban sampling location. It was also found that during the sampling period at the same site, the quantity of TGM transported to or from the sampling site was mainly influenced by the duration and frequency of wind occurrence from certain directions. Ó

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Section: Diurnal Changes In Atmospheric Mercury Concentrationsmentioning

confidence: 99%

Section: Effect Of Wind Frequencies On Atmospheric Mercury Fluxmentioning

confidence: 99%

Atmospheric mercury monitoring survey in Beijing, China

et al. 2002

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“…Une station est située en milieu rural, à Saint-Anicet (Québec, Canada), sur la rive sud du fleuve Saint-Laurent (45°07' de latitude nord et 74°17' de longitude ouest) (voir les détails dans POISSANT et CASIMIR, 1998). Une autre station est située dans un marécage de la baie Saint-François, au lac Saint-Pierre (46°06' de latitude nord et 72°56' de longitude ouest), entre Montréal et Trois-Rivières (voir les détails dans .…”

Section: Localisation Des Sites De Mesuresunclassified

“…Elle est en acier inoxydable et enduite d'une pellicule de Téflon sur ses surfaces. Elle a un diamètre de 40 cm à sa base (une superficie de 0,13 m 2 (A)) et son volume est de 10 L (POISSANT et CASIMIR, 1998 ;POISSANT ef al., 1999). La mesure dynamique demande un renouvellement continu de l'air à l'intérieur de la chambre.…”

Section: 3unclassified

Les échanges surface-atmosphère du mercure gazeux dans l'écosystème lac Ontario/fleuve Saint-Laurent

Poissant¹

2005

rseau

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La volatilisation du mercure des surfaces vers l'atmosphère et les dépôts atmosphériques du mercure sont des phénomènes importants dans la dynamique globale du mercure. Les échanges surface-atmosphère du mercure gazeux dans l'écosystème lac Ontario/fleuve Saint-Laurent sont variables dans le temps et dans l'espace. Bien que le modèle de la double couche montre que la grande partie des écosystèmes aquatiques sont en sursaturation par rapport à la constante d'Henry, des observations in situ, à l'aide de techniques de chambre à flux, montrent que des dépôts gazeux sont également possibles. Les dépôts gazeux du mercure dans l'écosystème lac Ontario/fleuve Saint-Laurent oscillent entre 0 et 4,66 ng/m2/h alors que les valeurs de volatilisation varient entre 0 et 9,28 ng/m2/h. Globalement, la volatilisation médiane du mercure est de 0,77 ng/m2/h alors que le dépôt gazeux médian est d'environ un ordre de grandeur inférieur (0,075 ng/m2/h). En été, l'ensemble des dépôts atmosphériques du mercure semble être mis à contribution lors de la volatilisation du mercure au-dessus des sols. Il semble que la majeure partie de cette volatilisation serait en fait de la ré-émission du mercure vers l'atmosphère. En hiver, seule la portion gazeuse des dépôts de mercure semble être ré-émise vers l'atmosphère. Plusieurs observations dans un marécage fluvial du lac Saint-Pierre (baie Saint-François) montrent que les flux de volatilisation du mercure sont supérieurs en période sèche qu'en période inondée (0,83 vs. 0,52 ng/m2/h). Ainsi, en période d'inondation le mercure réactif disponible pour la volatilisation serait en compétition avec les mécanismes responsables pour la méthylation du mercure (bio-disponible) et/ou la formation du sulfure de mercure (inerte sous forme de cinabre). Cet article a pour objectifs de présenter et discuter les échanges surface-atmosphère du mercure gazeux dans l'écosystème lac Ontario/fleuve Saint-Laurent.

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“…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

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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Water-air and soil-air exchange rate of total gaseous mercury measured at background sites

Cited by 261 publications

References 16 publications

Atmospheric mercury monitoring survey in Beijing, China

Atmospheric mercury monitoring survey in Beijing, China

Les échanges surface-atmosphère du mercure gazeux dans l'écosystème lac Ontario/fleuve Saint-Laurent

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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