I am guessing here but I would think that the vast majority of the mercury found in the fly ash would settle close to the smoke stack that it came out of. The larger the particle size the less distance it will drift or blow away from the source. Now the very find particulate matter will actually float in the air for long periods of time. Those fine particles may travel thousands of miles away from the point source. This will help dispurse the initial pollutants. But when you have a smoke stack that is continusouly streaming out pollants such as fly ash containing mercury in trace amounts it will eventually build up in the downwind environemnt.

I know that the levels in the fish are measured in PPM. I suspect that is parts per million parts on a weight/weight basis. In air pollution we measure PPM on a vol/vol basis by converting the molecular weight of the gas into a gas volume. One mole of a gas at STP will occupy a certain volume of space.

Anyway bottom line is that I would think that there is more mercury closer to the smoke stack in most cases.

I would have to know the particle size distribution of the gases and how the trace mercury was distributed in each particle size category. That would be a job to figure out. Maybe someone has already figure that out.

I do know that coal is a trickly devil to test. The coal seam can contain coal of different chemical composition.

Normally they will take a shovel of coal from a pile and store it in a burlap sack. They will take so many shovels of coal from the pile and then try to mix the samples up and then crush it. The crushed coal is then homogonized and divide up over and over again until they get a small plastic jar that is represenative of the entire coal pile out in the field. They will take samples from the coal pile as the loader takes a scoop out of the coal pile and loads that into a coal car that is waiting at the site. As the coal car is loaded by a front end loader a sampler will continue to take samples of the coal pile after each scoop from the front end loader. I know that at the end of the day the guy sampling the coal is tired, dirty as hell and ready for a hot shower and a good meal. I only did that job for a couple of days and believe me it will take a toll on your body. Just breathing in the coal dust on a hot summer day will about kill a man. LOL. I did this a few days to see what the coal sampling guys had to put up with. To test the coal we took small samples of the sample jar and tested them for sulfur content, BTU heat content, Ash content and melting point. Some of our clients wanted special analysis of the coal and we performed other tests on those samples.

I do remember one of the labs chemist testing water samples for mercury and that test was a hard test to conduct. It took more time to conduct than the other tests. It's was not easy testing for trace amounts of mercury. We also tested water samples for cynaide and other contaminates. We did PCB test also. Most all we did was test the water and soils for inorganic pollutants. All the organic tests other than some generic test were sent to California for testing out there at our Organic Testing laboratory. We had labortories located all around the world. Today the lab I worked for is owned by Haliburton. Our lab started out as a geological testing lab and tested mainly core samples from the earth. Then it grew into testing the coal for the local coal companies and the power plants that were purchasing the coal. We tested their coal to document the amount of sulfur in the coal to meet their environemental permit conditions.



Regards,

Moose1am