Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Atmospheric Mercury Has Declined -- But Why?

10.06.2003

The amount of gaseous mercury in the atmosphere has dropped sharply from its peak in the 1980s and has remained relatively constant since the mid 1990s. This welcome decline may result from control measures undertaken in western Europe and North America, but scientists who have just concluded a study of atmospheric mercury say they cannot reconcile the amounts actually found with current understanding of natural and manmade sources of the element.

An international group of scientists, led by Franz Slemr of the Max Planck Institute for Chemistry [Max-Planck-Institut fuer Chemie] in Mainz, Germany, studied the worldwide trend of total gaseous mercury at six sites in the northern hemisphere, two sites in the southern hemisphere, and on eight ship transatlantic ship cruises since 1977. They have published their findings in Geophysical Research Letters, a journal of the American Geophysical Union.

The fixed sites ranged from the Canadian Arctic to Antarctica. In both hemispheres, total gaseous mercury increased in the late 1970s, apparently peaked in the late 1980s, decreased to a minimum in the mid 1990s, and has remained relatively constant since then. Concentrations in the southern hemisphere are about one-third less than in the northern hemisphere. These observations accord well, the researchers say, with data on mercury deposited in peat bogs and found in ice cores.

Scientists have believed that natural processes and human activities put about equal amounts of mercury into the atmosphere. Assuming that natural emissions and re-emissions of the historically deposited mercury have remained constant, the observed reduction of about 17 percent in concentration from 1990 to 1996 would have to result from a reduction of about 34 percent in manmade emissions during that period. This, the scientists say, is three to four times larger than the 10 percent decrease in manmade emissions suggested by previous studies. Therefore, either our understanding of manmade emissions or of the ratio of natural to manmade emissions probably has to be refined, they say.

The level of atmospheric mercury is important, even though at current levels, it is not directly toxic. The problem, says Slemr, "is that some 5,000 metric tons of atmospheric mercury are currently deposited worldwide every year. The atmospheric lifetime of elemental mercury is about one year and, thus, the mercury is deposited even in remote areas."

Further, Slemr says, some of the atmospheric mercury is deposited into soil and water, where it can be "transformed to methyl mercury, one of the most toxic compounds." In ocean water, methyl mercury concentrates in plankton and further accumulates in fish, especially those high in the food chain, such as tuna. High methyl mercury levels in tuna can lead to chronic diseases in persons who eat the fish, with pregnant women most in danger.

Therefore, the researchers say, it is essential that we better understand the amount and sources of mercury in the atmosphere. The amount of mercury emitted naturally is not well understood at present. With regard to manmade emissions, coal burning definitely emits mercury, and it was recently discovered that biomass burning is another important source. Waste incineration is also a source, but not yet well quantified. Further, says Slemr, the annual re-emission of a small fraction of the 200,000 metric tons of mercury deposited into the environment since Roman times is uncertain.

Slemr and his colleagues conclude that future emission inventories must take into account the difference between atmospheric mercury levels in the northern and southern hemispheres, as well as the historic and present day emission trends. Further research will be necessary with regard to the quantitative and qualitative sources of atmospheric mercury, both natural and manmade, for any emission inventory to be credible.

The study was funded in part by the Deutsche Forschungsgemeinschaft.

Harvey Leifert | AGU

More articles from Earth Sciences:

nachricht Small- and mid-sized cities particularly vulnerable
29.09.2016 | Universität Stuttgart

nachricht Tracking the amount of sea ice from the Greenland ice sheet
28.09.2016 | Ca' Foscari University of Venice

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

HLF: From an experiment to an establishment

29.09.2016 | Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

 
Latest News

New Multiferroic Materials from Building Blocks

29.09.2016 | Materials Sciences

Silicon Fluorescent Material Developed Enabling Observations under a Bright “Biological Optical Window”

29.09.2016 | Materials Sciences

X-shape Bio-inspired Structures

29.09.2016 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>