Oxygen

Deadly poison hydrogen sulfide induces suspended animation

Researchers from the Massachusetts General Hospital in Boston (USA) have announced that hydrogen sulfide (sulphide) gas, H2S, can induce a state of suspended animation in mice while maintaining normal blood pressure. It is hoped that this result eventually will help in the treatment critically-ill patients. This result was presented at the American Physiological Society conference, "Comparative Physiology 2006: Integrating Diversity," in Virginia Beach, Virginai, USA, October 2006.

Hydrogen sulfide (sulphide) gas, sometimes called sewer gas, produces a noxious odour often described as a rotten egg smell. This highly toxic gas occurs naturally in swamps, some springs, and volcanoes.

The researchers administered 80 parts per million of H2S gas to their and found that their:

  • heart rate fell from 500 beats per minute to 200 beats per minute
  • respiration rate decreased from 120 breaths to 25 breaths per minute
  • core body temperature fell from 38° C to 30° C
  • activity level fell dramatically, moving only when the researchers touched them or shook their chambers

After the mice returned to breathing normal air they quickly returned to normal. Normally, as oxygen consumption goes down and heart rate decreases, blood pressure decreases also. Since the heart rate of the mice fell by more than 50%, the researchers expected blood pressure to fall, but it didn't.

"These findings demonstrate that mice that breathe 80 parts per million of hydrogen sulfide become hypothermic and decrease their respiration rate, heart rate and cardiac output without affecting stroke volume or mean arterial pressure," the authors said. This line of research could have a variety of helpful applications, including sustaining the function of organs of critically ill people, Ichinose said. It may also be possible to use the finding for patients undergoing surgery. This would be an advance, because anesthesia usually causes blood pressure to drop.

Manganese blocks hydrogen sulphide in water systems

Trace amounts of manganese is essential to human health. Now, a team of scientists from the University of Delaware, Scripps Institution of Oceanography, the University of Hawaii, and Oregon Health and Science University has found that a dissolved form of manganese, Mn(III), is important in waterways such as the Black Sea and Chesapeake Bay. It can keep toxic hydrogen sulfide (sulphide) zones in check.1

The research is based on research conducted in 2003 that explored the chemistry of the Black Sea. Nearly 90% of the mile-deep system is a no-oxygen "dead zone," containing large amounts of naturally produced hydrogen sulfide (sulphide), which is lethal to most marine life. Only specialized microbes can survive in this underwater region.

Above this "dead zone" in the Black Sea lies another aquatic layer, the "suboxic zone,". This has both minimal amounts of oxygen and minimal amounts of hydrogen sulfide. This layer may be up to 40 metres (130 feet) deep in the Black Sea, but only 4 metres (13 feet) deep in the Chesapeake Bay.

The research team found that a chemical form of dissolved manganese, Mn(III), can maintain the existence of the suboxic zone by reacting as a reductant with oxygen and as an oxidant with hydrogen sulfide, preventing deadly hydrogen sulfide from reaching the surface layer of water, which is where most fish, algae and microscopic plants live. The scientists used an electrochemical analyzer to locate and map the chemistry of the suboxic zone in real time under changing salinity, temperature and depth.

The finding is surprising, George Luther (Delaware) said, because dissolved manganese as Mn(III) was assumed not to form in the environment and thus was largely ignored by scientists. The research team conclude that "Manganese in natural oxygen-poor waters can persist in a +3 oxidation state, a state previously seen only in the lab, necessitating a major revision of the current understanding of manganese aqueous geochemistry".

"Now we've learned that this form of dissolved manganese [Mn(III)] can constitute almost all the dissolved manganese in suboxic water columns and can react with hydrogen sulfide and other compounds that only solid manganese(IV) phases were thought to be doing," Luther noted. "It is also more reactive than the solid phases."

"Our research shows that the impact of dissolved manganese(III) is significant in any aquatic environment, including lakes, plus sediments on the seafloor and soils on land," Luther said. "And for the public who live near the water, dissolved manganese(III) actually helps prevent naturally occurring hydrogen sulfide from getting to the surface, so it prevents both fish kills and the foul odours from this compound's telltale 'rotten egg' smell."

Record ozone loss over South Pole

OzoneOzoneOzone measurements made by the European Space Agency Envisat satellite reveal the ozone loss of 40 million tons by 2 October in 2006 and that this exceeds the record ozone loss of about 39 million tons for the whole of 2000. The size of this year's ozone hole is 28 million square km.

The Ozone layer is a protective layer found about 25 kilometres above us mostly in the stratospheric stratum of the atmosphere that acts as a sunlight filter shielding life on Earth from harmful ultraviolet rays. Over the last few years the effective thickness of the ozone layer declined, increasing the risk of skin cancers, cataracts and harm to marine life. The thinning of the ozone layer is caused by the presence of pollutants in the atmosphere originating from, for instance, chlorofluorocarbons (CFCs), which have still not vanished from the air although banned under the 1987 Montreal Protocol.

"Such significant ozone loss requires very low temperatures in the stratosphere combined with sunlight. This year’s extreme loss of ozone can be explained by the temperatures above Antarctica reaching the lowest recorded in the area since 1979," European Space Agency Atmospheric Engineer Claus Zehner said.

Background Information

Ozone (O3) is another allotrope of oxygen. It is bent with a O-O-O angle of about 123° It is formed from electrical discharges or ultraviolet light acting on O2. It is an important component of the atmosphere (in total amounting to the equivalent of a layer about 3 mm thick at ordinary pressures and temperatures) which is vital in preventing harmful ultraviolet rays of the sun from reaching the earth's surface. Aerosols in the atmosphere have a detrimental effect on the ozone layer. Large holes in the ozone layer are forming over the polar regions and these are increasing in size annually. Paradoxically, ozone is toxic! Undiluted ozone is bluish in colour. Liquid ozone is bluish-black, and solid ozone is violet-black.

For chemical robots

IUPAC Name: ozone
Canonical SMILES: [O-][O+]=O
InChI: InChI=1/O3/c1-3-2

New form of carbon dioxide: amorphous

Only carbon from the Group 14 elements forms stable double bonds with oxygen under normal conditions. When frozen, carbon dioxide is known as "dry-ice". A non-molecular single-bonded crystalline form of carbon dioxide (phase V) exists at high pressure according to Italian and French researchers.1

Amorphous forms of silica (a-SiO2) and germania (a-GeO2) are known at ambient conditions but only recently has an amorphous, silica-like form of carbon dioxide, a-CO2. This is labelled a-carbonia and made by compression of CO2 at room temperature at pressures between 40 and 48 GPa (that's a staggering 400-500 thousand atmospheres).

During this compression, infrared spectra at temperatures up to 680 K show the progressive formation of C–O single bonds and the simultaneous disappearance of all infrared bands associated with molecular CO2. Raman and synchrotron X-ray diffraction measurements confirm the amorphous character of the CO2. Vibrational and diffraction data for a-SiO2 and a-GeO2 are closely related and calculations also suggest shows that a-CO2 is structurally homologous to a-silica (a-SiO2) and a-germania (a-GeO2).

This research helps to understanding the nature of the interiors of gas-giant planets where carbon dioxide may be squeezed at very high pressures. Maybe it could be used to make very hard glass because it is expected to be very stiff rather like diamond. The researchers ponder whether "small amounts of these new glasses could be of interest for technology applications like hard and resistant coatings for micro-electronics, for example."

Royal Society gives access to 340 years of landmark science

The complete archive of the Royal Society journals, including some of the most significant scientific papers ever published since 1665, is to be made freely available electronically for the first time until 2007.

The archive contains seminal research papers including accounts of Michael Faraday's groundbreaking series of electrical experiments, Isaac Newton's invention of the reflecting telescope, and the first research paper published by Stephen Hawking.

The Society's online collection, which until now only extended back to 1997, contains every paper published in the Royal Society journals from the first ever peer-reviewed scientific journal, Philosophical Transactions in 1665, to the most recent addition, Interface.

You can register for free. So now, for a time at least, you can read free of charge some extraordinary historical documents. Here are a few examples:

  • On the Constitution of the Atmosphere by John Dalton
  • On the Action of Radium Emanations on Diamond by William Crookes
  • The Separation of the Most Volatile Gases from Air without Liquefaction by James Dewar
  • On the Compressibilities of Oxygen, Hydrogen, Nitrogen, and Carbonic Oxide between One Atmosphere and Half an Atmosphere of Pressure, and on the Atomic Weights of the Elements Concerned.--Preliminary Notice by Lord Rayleigh

Note: this facility seems to have been withdrawn?

Water on Mars

A NASA press release claims that the Opportunity rover "has demonstrated some rocks on Mars probably formed as deposits at the bottom of a body of gently flowing saltwater." "Bedding patterns in some finely layered rocks indicate the sand-sized grains of sediment that eventually bonded together were shaped into ripples by water at least five centimeters (two inches) deep, possibly much deeper, and flowing at a speed of 10 to 50 centimeters (four to 20 inches) per second," said Dr. John Grotzinger, rover science-team member from the Massachusetts Institute of Technology, Cambridge, Mass.

Special interests threat to ozone layer?

The BBC report that special interests in a number of developed countries wish to to be allowed to continue using a bromine containing gas, methyl bromide, for various purposes such as crop fumigation. Methyl bromide is known to destroy ozone, O3, (an allotrope of oxygen, O2) and this is being debated at an international meeting in Canada. The Montreal Protocol does allow continued use of ozone-destroying gases for purposes agreed to be "critical", but is this really critical?

Oxygen and Carbon Found in Atmosphere of an Extrasolar Planet

The Hubble telescope has identified oxygen and carbon in the atmosphere of an extrasolar planet for the first time. The oxygen and carbon are evaporating from a "hot jupiter" planet HD 209458b, orbiting a star lying 150 light-years from Earth. HD 209458b is only 4.3 million miles from its Sun-like star, completing an orbit in less than 4 days. This is not a sign of life!

Carbonate minerals on Mars

A NASA press release indicates that NASA's Spirit, the first of two Mars Exploration Rovers on the surface within Mars' Gusev crater, has identified carbonate minerals "in the rover's first survey of the site with its infrared sensing instrument, called the miniature thermal emission spectrometer or Mini-TES. Carbonates form in the presence of water, but it's too early to tell whether the amounts detected come from interaction with water vapor in Mars' atmosphere or are evidence of a watery local environment in the past, scientists emphasized."

"We came looking for carbonates. We have them. We're going to chase them," said Dr. Phil Christensen of Arizona State University, Tempe, leader of the Mini-TES team. Previous infrared readings from Mars orbit have revealed a low concentration of carbonates distributed globally. Christensen has interpreted that as the result of dust interaction with atmospheric water. First indications are that the carbonate concentration near Spirit may be higher than the Mars global average.

After the rover drives off its lander platform, infrared measurements it takes as it explores the area may allow scientists to judge whether the water indicated by the nearby carbonates was in the air or in a suspected ancient lake. http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040109a/graph-carb...

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Copyright 1993-2011 Mark Winter [The University of Sheffield and WebElements Ltd, UK]. All rights reserved.