This suspended-animation state may be suitable for surgical applications. Very low doses of it can reduce metabolic rate, and it has been suggested that this could allow organ function to continue even when oxygen supply is limited, after a traumatic injury, for example. Yes, but there may just be medical uses for H 2S. This in turn led to oceanic bacteria reducing sulphate to produce large amounts of H 2S, killing aqueous plants and animals, both in the oceans and on land. The eruption of Siberian volcanoes led to large amounts of volcanic CO 2, leading to warming that depleted oceanic oxygen levels. It's been suggested that H 2S was responsible for a huge mass extinction of life about 250 million years ago, the "Permian-Triassic extinction event".
Right: Warning sign from Germany, which says "No ice-skating - danger of life - hydrogen sulphide in the water". Left: Warning sign to wear a gas-mask in enclosed spaces if H 2S is present. The celebrated Bogle-Chandler case - the mysterious deaths of Dr Gilbert Bogle and Mrs Margaret Chandler on a Sydney riverbank in 1963 - has recently been attributed to H 2S released from the Lane Cove River. H 2S is denser than air, and can accumulate in the bottom of unventilated spaces, such as sewers. Inhibition of cytochrome c oxidase in a similar manner to HCN has been suggested as a reason for its toxicity, but others believe that it could also involve a reactive S-containing species which depletes glutathione and activates oxygen.Īpart from people working with "sour gas" fields of natural gas, sewage workers are particularly at risk, as stagnant sewage can release large amounts of H 2S when agitated, and fatalities are regularly reported. Taken together, this means that a person exposed to high concentrations may get no warning. At 500 ppm, inhalation can cause immediate collapse and unconsciousness, whilst one breath at the 1000 ppm level results in immediate loss of consciousness, cardiac arrest and death. Levels around 150-250 ppm cause the sense of smell to disappear, and slightly higher levels may well be fatal. It can be detected by its "bad egg" smell at levels around 0.005 ppm (parts per million). Surprisingly toxic, roughly comparable to hydrogen cyanide. These two gases react together in a redox reaction, forming sulphur, which can often be seen as a yellow deposit round the crater of a volcano (see photo, right).Ģ H 2S (g) + SO 2 (g) 3S (s) + 2 H 2O (g) How toxic is hydrogen sulphide? Volcanoes emit sulphur mainly in the form of sulphur dioxide, but some hydrogen sulphide is released too this is why the smell of volcanoes is mainly that of SO 2 ("burning match") rather than bad eggs. 64,000 residents were evacuated, but 243 people died from breathing in the fumes, China's worst gas-field disaster. on December 23, 2003, releasing hydrogen sulphide.
There was an accidental sour-gas blow-out from a well in Kaixian County of southwest China at 10 p.m. The hydrogen sulphide content can present a real health hazard. Organic sulphur compounds present in crude oil have to be removed the sulphur they contain is converted to hydrogen sulphide, or to sulphur itself, which can be stored in blocks (shown below in blocks 25 feet tall on the prairie at Alberta, Canada). The H 2S can be removed by being converted to sulphur in the Claus process this is an important industrial source of sulphur. Some natural gas fields (such as Lacq in Aquitaine, France (shown right) Canada China the USA) yield gas which is often found to contain significant amounts of hydrogen sulphide, and is termed " sour gas". Most certainly not, eggs are only a very minor one. Is that the only source of hydrogen sulphide? Due to bacteria in the mouth, hydrogen sulphide may also be a cause of bad breath. The Curate: Oh no, My Lord, I assure you! Parts of it are excellent!ĭrawn by George du Maurier and published in the issue of Punchīacteria in the colon can form H 2S there, and it is released as a principal component of flatus.
Right Reverend Host: I'm afraid you've got a bad egg, Mr. Originally the expression meant to call something bad, good, out of politeness or deference nowadays, the term is used to mean something partly good and partly bad. Yes, it is formed when proteins contained in the egg are decomposed by bacteria, making H 2S, as in the famous Punch cartoon (below), which gave rise to the expression "a curate's egg". Hydrogen Sulphide, H 2S The smell of rotten eggs Hydrogen sulphide - Molecule of the Month March 2009 - HTML-only version
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