Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mercury in atmosphere could be washed out more easily than earlier believed

09.12.2005


Scientists for years have been at a loss to explain unexpectedly high levels of mercury in fish swimming the rivers and streams of areas like eastern Oregon, far away from industrial sources of mercury pollution such as coal-fired power plants.

New University of Washington research suggests mercury can be carried long distances in the atmosphere, combining with other airborne chemicals as it travels. These compounds are much more water-soluble and therefore are more easily removed from the air in rainfall.

Mercury generally is present in the atmosphere in only very small amounts compared with other pollutants, said Philip Swartzendruber, a University of Washington doctoral student in atmospheric sciences. But mercury does not break down and after it washes out of the atmosphere it can be converted to a more toxic form, methyl mercury. Even in places thought to be pristine, the more toxic form can become very concentrated as it is passed up the food chain.



"By the time mercury gets to the top of the food chain, it can increase by a factor of a million," he said. "It can go from being nearly undetectable in the air to being toxic to larger organisms."

Swartzendruber presents his team’s findings Thursday during the American Geophysical Union’s fall meeting in San Francisco. He is part of a team that began taking measurements of atmospheric mercury levels early this year atop Mount Bachelor, near Bend, Ore. At about 9,000 feet, the station is high enough to take readings from the bottom of the free troposphere, where substances such as mercury, carbon dioxide and ozone can travel great distances and remain for a long time. The free troposphere extends from about 5,000 feet in altitude to about 40,000 feet.

The researchers recorded mercury levels that included significant concentrations of a type called reactive gaseous mercury. "After nearly half a year of results, it is pretty clear things are going on up there," Swartzendruber said.

The researchers are only able to pinpoint a source of mercury if the air mass arrives at the observation station within a few days after the mercury is emitted. Measurements of other chemicals in the air help provide evidence of the origin, but after a few days in the free troposphere air masses dilute and can change chemically, masking their origin.

The research indicates there is a lot more mercury than previously believed that is available to be washed out of the atmosphere, even far away from industrial sources, Swartzendruber said. He noted that a large portion of atmospheric mercury comes from eastern Asia, and it can survive in the free troposphere for a year, perhaps more. But even a relatively small amount of mercury emitted in North America can settle to the Earth in remote, unspoiled regions.

The type called reactive gaseous mercury – basic, or elemental, mercury that has combined with another substance – is important because rain washes it out of the air very easily. It is likely that ozone, a common pollutant usually associated with smog, or other oxidants most often combine with elemental mercury to form reactive gaseous mercury, Swartzendruber said.

Contrary to what researchers previously thought, he added, high concentrations of reactive mercury can be present in the atmosphere far from industrial sources. That means either that elemental mercury can transform to the reactive variety in just a week or two, a much shorter time than scientists have believed, or that there is a large pool of reactive mercury at the top of the troposphere.

"We need to be looking for reactive gaseous mercury when we do air studies," Swartzendruber said. "It is possible it is being produced more quickly than our estimates, based on laboratory experiments."

The work continues the effort to understand how a chemical once thought to be inactive has become a global toxin. It also sheds light on why fish in streams far from people and industry are tainted with mercury.

"It’s definitely a step in understanding the global cycling of mercury and how this toxin is carried by the atmosphere and removed a great distance from its source," Swartzendruber said.

Vince Stricherz | EurekAlert!
Further information:
http://www.washington.edu

More articles from Earth Sciences:

nachricht Impacts of mass coral die-off on Indian Ocean reefs revealed
21.02.2017 | University of Exeter

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Microhotplates for a smart gas sensor

22.02.2017 | Power and Electrical Engineering

Scientists unlock ability to generate new sensory hair cells

22.02.2017 | Life Sciences

Prediction: More gas-giants will be found orbiting Sun-like stars

22.02.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>