Originally posted by Rockabunny
reply to post by Rezlooper
Thank you for replying. It is a unique smell I can't really describe it...there is a smell of sulphur to it. People around here don't pay any attention to it. I have to close my windows when it "rolls" in. I have smelled it in different areas, leave that area, go a few miles down the road and the air is fresh again. I don't know who to bring it up to, everyone just calls it swamp smell, or swamp gas. We had a terrible odor roll through our neighborhood about a month ago in the middle of the afternoon, lasted about an hour, then was gone. I immediately thought of your posts and told a neighbor about your research. It was dismissed...as you guessed it...just the swamp smell. We don't live near a swamp closest one is about 5 miles away. Thank you again, thought you would be interested.
Hydrogen sulfide is the chemical compound with the formula H2S. It is a colorless gas with the characteristic foul odor of rotten eggs; it is heavier than air, very poisonous, corrosive, flammable and explosive. Hydrogen sulfide often results from the bacterial breakdown of organic matter in the absence of oxygen, such as in swamps and sewers; this process is commonly known as anaerobic digestion. H2S also occurs in volcanic gases, natural gas, and some well waters.
Exposure to lower concentrations can result in eye irritation, a sore throat and cough, nausea, shortness of breath, and fluid in the lungs (pulmonary edema). These effects are believed to be due to the fact that hydrogen sulfide combines with alkali present in moist surface tissues to form sodium sulfide, a caustic. These symptoms usually go away in a few weeks.
Long-term, low-level exposure may result in fatigue, loss of appetite, headaches, irritability, poor memory, and dizziness.
Chronic exposure to low level H2S (around 2 ppm) has been implicated in increased miscarriage and reproductive health issues among Russian and Finnish wood pulp workers, but the reports have not (as of circa 1995) been replicated.
0.00047 ppm or 0.47 ppb is the odor threshold, the point at which 50% of a human panel can detect the presence of the compound.
0.0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide, normally described as resembling "a rotten egg". OSHA has established a permissible exposure limit (PEL) (8 hour time-weighted average (TWA)) of 10 ppm.
10–20 ppm is the borderline concentration for eye irritation. 20 ppm is the acceptable ceiling concentration established by OSHA.
50 ppm is the acceptable maximum peak above the ceiling concentration for an 8 hour shift, with a maximum duration of 10 minutes.
50–100 ppm leads to eye damage.
At 100–150 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.
320–530 ppm leads to pulmonary edema with the possibility of death.
530–1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing.
800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure (LC50).
Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath. Although respiratory paralysis may be immediate, it can also be delayed up to 72 hours.
I think this is one of the most fascinating subjects I have ever read on ATS. Thank you for giving my brain something new to think on!
Interspecies electron transfer plays a key role in the functioning of methane-producing microbial communities, which have a significant impact on the global carbon cycle (Stams and Plugge, 2009; Sieber et al., 2012). Organic matter mineralization to methane by microbial processes contributes to 69% of the atmospheric CH4 (Conrad, 2009)
Methanogenic Archaea uses electrons from H2/formate/shuttles or directly to reduce CO2 to CH4 (Morris et al., 2013;Rotaru et al., 2014; Sieber et al., 2014).
Interspecies electron transfer via H2was first demonstrated almost four decades ago in a defined co-culture (Bryant et al., 1967) of the “S organism,” which converted ethanol to acetate and H2, only in the presence ofMethanobacterium ruminantium, which consumed H2 for the reduction of CO2to CH4 (Bryant et al., 1967).
H2 is a very powerful electron donor under anoxic conditions and must be continuously removed by partner organism in order for the syntrophic interaction to take place (Nedwell and Banat, 1981; Lovley and Ferry, 1985; Kleerebezem et al., 1999; Wintermute and Silver, 2010).
"1) Our first observations of elevated methane levels, about ten times higher than in background seawater, were documented already as we climbed up the steep continental slope at stations in 500 and 250 m depth."
"2) Using the mid-water sonar, we mapped out an area of several kilometers where bubbles were filling the water column from depths of 200 to 500 m. During the preceding 48 h we have performed station work in two areas on the shallow shelf with depths of 60-70m where we discovered over 100 new methane seep sites."
A scientist on the Oden has blogged about the seabed methane emissions saturating the water column and entering the atmosphere - terming it a "megaflare." Ulf Hedman, Science Coordinator, Swedish Polar Research Secretariat comments:
"We see the bubbles on video from the camera mounted on the CTD or the Multicorer. All analysis tells the signs. We are in a Mega flare. We see it in the water column we read it above the surface an we follow it up high into the sky with radars and lasers. We see it mixed in the air and carried away with the winds."