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hboy007

Wed Jan 23 2013, 10:25PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374

At least in natural gas production mercury contamination is a significant issue. Liquid mercury condenses in some stages of raw gas processing, residual amounts of mercury metal have to be scrubbed with activated absorbers or cooled traps. In addition, inorganic compounds of mercury may be present.
Given that there is very limited information and media presence, one might assume that the mercury emissions from the product itself are negligible.
In the following documents it is being pointed out that emissions due to flaring are significant and incidents with plant workers being exposed to large amounts of mercury do happen. Now I wonder how much mercury is left in the natural gas delivered to the customer after (economically) "reasonable reduction" through filtering, since efficient absorbers are rather expensive.

related documents in
English:

German:

additional information on mercury toxicity can be obtained from peer-reviewed medical publications. There's also a lot of controversy going on in the internets. For a quick video, check out

Conundrum

Sat Jan 26 2013, 10:47AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Interesting articles.
Does this mean many people who use gas at home could be being slowly poisoned with Hg?
-A

Nik

Sat Jan 26 2013, 06:55PM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

The short answer is no reason to get all alarmist about it. If there was a danger it would have probably shown up earlier when practices were more lax. In addition gas appliances all supposed to vent outside (furnaces and water heaters via a chimney stoves via range hood) I doubt there is an appreciable exposure to mercury in a modern home.

In lesser developed areas of the world that have already high mercury content I would imagine there would be considerably higher exposure but how much combusted natural gas over time would you have to inhale to suffer from the effects of mercury even? Is it more than you would need to inhale to suffer other long-term or fatal effects from the rest of the gas?

hboy007

Sat Jan 26 2013, 07:05PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374

Nothing here to get overly worried about. I just wanted to bring this source of mercury to attention even if cooking with a gas oven or stove on a daily basis and with the windows closed creates an exposure one or two orders of magnitude less than the average daily uptake through food.
I just didn't even think about it before and it appears that numbers are hard to find when it comes to a quantitative consideration.

Nik

Sat Jan 26 2013, 07:39PM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

I am curious if it could be measured and extrapolated out for a lifetime. Would it be grams or ug?

nixie

Sat Jan 26 2013, 08:05PM

Registered Member #3908 Joined: Tue May 24 2011, 09:40PM
Location: Gilbert, Arizona USA
Posts: 68

Nik wrote ...

I am curious if it could be measured and extrapolated out for a lifetime. Would it be grams or ug?

Methylmercury can be measured through a hair test, or whole blood analysis.

The scaling varies by the source. IIRC the FDA (USA) assigns a 1ppm limit to fish or shellfish.
Measurement in humans are in ug. Average human daily exposure is estimated at 50ng in developed countries through food ingestion.
Depending on the form (chlorides or methyl) it can leave the body through urine or breath, so cumulative measurements may be best performed through hair follicle tests.

We use NG for various heating and cooking in our home. Most notably the six burner cooking island. The exhaust fan isn't always used.

This subject sparked my interest in determining a method to measure both the NG mercury levels, and cumulative value in humans without a Gas Chromatograph.

Regards, Jeff

Proud Mary

Sat Jan 26 2013, 09:38PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Most sensitive mercury detector ever costs under $10

Nik

Sun Jan 27 2013, 12:15AM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

Cool bit of kit. I wonder if it can distinguish between contaminants. The 10$ price tag is a little misleading though. Gasoline is the cheapest way to go 400 km/h if you don't include the price of the bugatti ;)

nixie

Sun Jan 27 2013, 01:59AM

Registered Member #3908 Joined: Tue May 24 2011, 09:40PM
Location: Gilbert, Arizona USA
Posts: 68

Proud Mary wrote ...

Most sensitive mercury detector ever costs under $10

Vaporware. Although I do like the concept of a disposable test element.
Perhaps a chemical reaction, similar to a ph strip indication could deliver a worthwhile resolution.

Regards, Jeff

Bored Chemist

Sun Jan 27 2013, 07:13PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

The high pressure gas pipeline network in the UK runs at pressures up to 85 bar.
The vapour pressure is about 1.2Âµ m Hg
That's a couple of parts per million or so.
So, if there was bulk liquid mercury in the pipe network and the gas was saturated then, once it expanded to 1 bar, there would be 0.02 ppm in the gas as it reached the burners.
The occupational exposure limits are of the order of 0.02mg/m^3
That's about .15 ppm
So, as long as the gas was diluted about 8 fold before you breathed it in, you wouldn't need to worry too much about the mercury.
On the other hand, you would need to worry about the lack of oxygen.

Also, of course, most of the mercury in the gas will be lost through the flue.
Feel free to check my maths, but as far as I can see, it's a potential issue, particularly at the production plant, but it's not something you need to worry about in the home.

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