[Wonder Warthog]

"I am not sure why coal fired power plants are the cause in the United States -- seems like scrubbers in the chimney should help remove this, but maybe mercury is too light an element to be easily scrubbed."

Not because it is too light, but because it is being sent "up the flue" as metallic mercury vapor, which is not highly reactive with current scrubbing chemistries. Maybe if they added sodium hydrogen sulfide to the scrubbing spray, but that would probably cost a fortune.

[topher]

Maybe my analysis is too simple, but if you put a turn in the smoke stack (horizontal), spray it with water, and then drain the water into a special tank.

Basically, just put a couple of "L"s into the smoke stack. Then the real cost is building such a smoke stack, and draining the water into a waste water tank.

Such a system would have up front capital costs, but the only additional cost in operation would be processing the waste water.

I do think it is a worthwhile use of tax dollars to try to make industry competitive but the environment clean. Tax credits for cleaning contaminates would relive energy sticker shocks.

[Eric in the Ozarks]

There is a new control system being developed by a guy in Minnesota. I think its called Enviroscrub and uses another heavy metal to trap mercury, sulfur and other bad actors.