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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."
Many agree that replacing conventional petrol driven cars with hydrogen is a good idea provided the hydrogen does not originate in a process involving oil as the only product from hydrogen burning is water, rather than carbon dioxide.
However the road to hydrogen-powered vehicles will not be easy, industry experts state. Representatives of European and American car and energy companies at the National Hydrogen Association convention said hydrogen technology is feasible, but faces big challenges to become commercially viable.
"We all have our homework to do in the coming years," said Klaus Bonhof, manager of the alternative fuels division of DaimlerChrysler AG. "We must produce technology viable in volume, and that technology must be commercially applicable."
Several car compnaies had hydrogen-powered vehicles on display at the conference, but all have similar technological challenges, including costs that range up to a million dollars a piece and limited range on a hydrogen fill-up. While a hydrogen-pwered car can travel 45 to 50 miles on a gallon, the fuel tank only provide a range of 125 to 150 miles. This is because hydrogen is put in a car as a liquid at very low temperatures, but reverts to a gas as on warming. The gas produced has to be vented while the car is not being used so that after a few days the tank will be empty.
The industry is working on this and BMW vice president of clean technology Frank Ochmann said BMW is testing an insulated tank that would keep hydrogen cold and liquid. "If you put in this tank a snowman, it would take about thirteen years to melt down," he said.
Developing hydrogen fuel station is easy part, experts said as hydrogen is already shipped to industrial users in tanks or moved through pipelines. BMW estimates it will be 2025 before hydrogen powered vehicles are commonly produced and sold.
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.
Researchers at the Carnegie Institution of Washington (Washington DC, USA) have managed to make a remarkable alloy of hydrogen and oxygen from water! They used X-rays to dissociate water at high pressure to form a solid mixture, that is, an alloy, of molecular oxygen (O2) and molecular hydrogen (H2).
The researchers placed some water under an extremely high pressure, about 170,000 atmospheres (17 Gigapascals), using a diamond anvil and then beamed high-energy X-rays at the water. Nearly all the water molecules split and reformed as a solid alloy of O2 and H2. The X-rays are key to cleaving the O—H bonds in water. Without it, the water remains as a high-pressure form of ice known as ice VII. Ice VII is one of at least 15 kinds of ice that exist under various high pressure and variable temperature conditions.
Russell Hemley of the Carnegie Institution of Washington said "we managed to hit on just the right level of X-ray energy input. Any higher, and the radiation tends to pass right through the sample. Any lower, and the radiation is largely absorbed by the diamonds in our pressure apparatus."
The researchers subjected the alloy to a range of pressures and temperatures, and also bombardment with X-ray and laser radiation. Provided the alloy is kept at about 10,000 times atmospheric pressure at sea level (1 Gigapascal), it withstands the treatment. Although clearly a crystalline solid, more experiments are needed to determine the alloy's precise crystal structure.
"The new radiation chemistry at high pressure was surprising," said Wendy Mao of the Los Alamos National Laboratory in the USA. "The new alloy containing the incompatible oxygen and hydrogen molecules will be a highly energetic material." An explosive alloy!
Scientists at NASA's Johnson Space Center in Houston have shipped pieces of the Genesis polished aluminium collector to researchers at Washington University in St. Louis, marking the first distribution of a Genesis scientific sample from JSC since the science canister arrived there Oct. 4, 2004. The sample, the first to be allocated for Genesis early science analysis, may hold important evidence about the overall composition of the sun.
While much of the solar wind is hydrogen, it is hoped that Genesis captured samples of many elements in the periodic table. An analysis of these elements will help to determine the sun's composition in detail. Several important Genesis science objectives will be investigated as part of the Early Science Return, including studies of noble gas isotopes in bulk solar wind and nitrogen isotopes.