Contributions from coal and industrial materials to mercury in air, rainwater and snow.

The mean mercury level in some British coals was 0.97 (range 0.13-2.28) ppm. Mean values of 0.01-3.3 ppm have been reported for coals elsewhere in the world with maxima upto 300 ppm. Release of mercury from coal used all over the world lies in the range 0.14-2.72 x 10(9) g yr-1 depending on mean mercury concentrations in the coal and amount of mercury trapped by precipitators before release from chimney stacks. The amount released from cement manufacture is estimated to be 2.5 x 10(8) g yr-1. Iron ores had 0.09 (range 0.02-0.28) ppm, minerals 0.31 (range 0.01-0.73) ppm, the ingredients used in cement contained between 0.03-0.46 ppm, rainwater 16.7 (range 6-30) ng 1(-1), snow 13 (range 4-21) ng 1(-1) and air levels were 18.9 (range 1-66) ng m-3. Proposals to burn more coal for energy are discussed in relation to (i) the mercury released from it, (ii) the mercury already present in the environment which is constantly being revaporized and redistributed, and (iii) the mercury washed out of the atmosphere into permanent sinks such as marine sediments.