La atmósfera sobre el Mar Muerto contiene grandes concentraciones de mercurio oxidado/Air Above Dead Sea Contains Very High Levels of Oxidized Mercury

Según los investigadores, la atmósfera del Mar Muerto está cargada con mercurio oxidado. En esa zona se encuentran algunos de los mayores niveles de mercurio oxidado, aparte de las regiones polares.
Daniel Obrist y sus colegas del Desert Research Institute de Reno, Nevada (E.E.U.U.) y de la Hebrew University de Israel han encontrado y medido varios periodos con niveles extremadamente elevados de mercurio oxidado. El mercurio atmosférico puede estar en estado elemental u oxidado. Procede de fuentes naturales y antropogénicas y en la atmósfera se convierte de una forma a otra. Las especies oxidadas se depositan rápidamente después de su formación, siendo ésta la manera en que el mercurio, un potente neurotóxico, encuentra su camino en los ecosistemas globales, acumulándose en la cadena alimentaria a través de la pesca oceánica y llegando hasta el hombre.
Hasta ahora, las observaciones de concentraciones elevadas de mercurio oxidado se habían limitado a la atmósfera polar, en la que se forma mercurio oxidado durante los denominados 'eventos de disminución de mercurio atmosférico'. En ellos el mercurio elemental es convertido en mercurio oxidado que rápidamente se deposita sobre la superficie terrestre. Estos eventos pueden aumentar en cientos de toneladas cada año, la cantidad de mercurio en estos entornos árticos sensibles.

(GEM es Mercurio Elemental Gaseoso y RGM es Mercurio (oxidado) Gaseoso Reactivo)

Se pensaba hasta ahora que las temperaturas altas impedían estos procesos, pero se ha encontrado uno similar en el Mar Muerto, a temperaturas de 45ºC. Los mecanismos implicados en la conversión del mercurio en el Mar Muerto son similares a los de las regiones polares y son causados por el bromo.
Los investigadores opinan que los niveles de bromo observados sobre los océanos podrían ser lo bastante grandes como para iniciar la oxidación del mercurio. "Hemos descubierto que el bromo puede oxidar al mercurio en la atmósfera y lejos de los Polos, a latitudes medias. Esto apunta a un papel importante de la oxidación del mercurio inducida por el bromo sobre los océanos de todo el mundo"
Los resultados se publicaron on-line el 28 de noviembre en la revista 'Natural Geoscience'


Researchers have found that the atmosphere over the Dead Sea is laden with oxidized mercury. Some of the highest levels of oxidized mercury ever observed outside the Polar Regions exist there.
Daniel Obrist and colleagues at the Desert Research Institute in Reno, Nevada (USA), and at Hebrew University in Israel, measured several periods of extremely high atmospheric oxidized mercury. Mercury exists in the atmosphere in an elemental and in an oxidized state. It's emitted by various natural and human processes, and can be converted in the atmosphere between these forms. The oxidized form is deposited quickly after its formation, and that is the way in which mercury, a potent neurotoxin, finds its way into ecosystems accumulating through the food chain, via the fish caught in oceans and arriving at last to the man..
Until now, the observations of high naturally-occurring oxidized mercury levels had been limited to the polar atmosphere, where oxidized mercury is formed during 'atmospheric mercury depletion events' in which elemental mercury is converted to oxidized mercury, which is then readily deposited on earth surfaces. These events may increase mercury loads to sensitive arctic environments by hundreds of tons of mercury each year.

(GEM: Gaseous Elemental Mercury; RGM: Reactive (oxidized) Gaseous Mercury)

High temperatures were thought to impede this chemical process, but now a similar process has been found above the Dead Sea, a place where temperatures reach 45 degrees Celsius. The mechanisms involved in the conversion of mercury above the Dead Sea are similar to those in Polar Regions and are driven by bromine.
The researches also think that bromine levels observed above oceans may be high enough to initiate mercury oxidation. "We discovered that bromine can oxidize mercury in the mid-latitude atmosphere, far from the poles. That points to an important role of bromine-induced mercury oxidation in mercury deposition over the world's oceans."
The results were published online November 28th in the journal Nature Geoscience

Tomado de/Taken from Science Daily

Resumen de la publicación/Abstract of the paper
Bromine-induced oxidation of mercury in the mid-latitude atmosphere
Daniel Obrist, Eran Tas, Mordechai Peleg, Valeri Matveev, Xavier Faïn, David Asaf and Menachem Luria
Nature Geoscience 4, 22–26 (2011)
Mercury is a potent neurotoxin, which enters remote ecosystems primarily through atmospheric deposition. In the polar atmosphere, gaseous elemental mercury is oxidized to a highly reactive form of mercury, which is rapidly removed from the atmosphere by deposition. These atmospheric mercury-depletion events are caused by reactive halogens, such as bromine, which are released from sea-ice surfaces. Reactive halogens also exist at temperate and low latitudes, but their influence on mercury in the atmosphere outside polar regions has remained uncertain. Here we show that bromine can oxidize gaseous elemental mercury at mid-latitudes, using measurements of atmospheric mercury, bromine oxide and other trace gases over the Dead Sea, Israel. We observed some of the highest concentrations of reactive mercury measured in the Earth’s atmosphere. Peaks in reactive mercury concentrations coincided with the near-complete depletion of elemental mercury, suggesting that elemental mercury was the source. The production of reactive mercury generally coincided with high concentrations of bromine oxide, but was also apparent at low levels of bromine oxide, and was observed at temperatures of up to 45 °C. Using a chemical box model, we show that bromine species were the primary oxidants of elemental mercury over the Dead Sea. We suggest that bromine-induced mercury oxidation may be an important source of mercury to the world’s oceans
Información adicional/Suplementary information