1. Hg data part of WoCQI coal analysis project Proximate, Ultimate Major and minor elements Se, Hg by CVAA, Precision ± 10%, d.l. 0.02 ppm Engineering parameters Strategy of Sampling Identify and collect samples from the largest mines 328 Samples of coal used for electric power production and industrial facilities. 305 are run-of-mine samples. Mean = 0.15; Min. 0.02; Max. 0.69 Hg data for China coals Collaboration between USGS & State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang

3. Censored data* <0.02 ppm -A small percentage- Replacement factor = 0.55 [ = 0.011 ppm] *Sanford, R.F., Pierson, C.T., and Crovelli, R.A., 1993. An objective replacement method for censored geochemical data., Mathematical Geology, vol. 25, 59-80. Chlorine data All 305 samples by ion electrode (d.l. 150 ppm) 40 samples re-done using direct combustion Cl analyzer (d.l. 10-15 ppm) China Coal Samples

5. Guizhou Province Commercial vs. Mineralized Coal

6. Comparison with Other Studies This Study n = 305 Mean = 0.15 ppmThis Study n = 305 Mean = 0.15 ppm Wang et al. n = 234 Mean = 0.22 ppm Huang & Yang n = 1466 Mean = 0.15 ppm Zhang et al. n = 990 Mean = 0.16 ppm USGS COALQUAL (in ground U.S. coals) Mean = 0.17 ppm EPA ICR (delivered U.S. coals) Mean = 0.10 ppm