The team was able to derive new emissions factors based on data from Chinese government programs that analyzed nearly 5000 coal samples taken throughout the country. (sciencemag.org)
However, those emission factors have shortcomings because they are based on analyses of only a few coal samples. (eia.gov)
Doughty gathered coal samples from mines throughout the U.S.. By measuring the coal elemental concentrations, he found elements needed by plants, like phosphorus, were more abundant and much better distributed during the era of the dinosaurs than the Carboniferous. (sciencedaily.com)