Trace gas Trace gas The most abundant gases in the atmosphere are nitrogen (78.1%), oxygen (20.9%), and argon (0.934%). Combined, oxygen, argon, and nitrogen make up 99.934% of the gases in the atmosphere (not including water vapor). The other gases that are not part of the 99.934% of the atmosphere are called trace gases. The abundance of a trace gas can range from a few parts per trillion (ppt) by volume to several hundred parts per million by volume (ppmv). When a trace gas is added into the atmosphere, that process is called a "source". There are two possible types of sources
Shale gas in the United States thickness of the Barnett varies from 100 to , but most economic wells are located where the shale is between 300 and thick. The success of the Barnett has spurred exploration of other deep shales. In 2007, the Barnett shale (Newark East) gas field produced of gas, making it the second-largest source of natural gas in the United States. The Barnett shale currently produces more than 6% of US natural gas production. In April 2015, Baker Hughes reports that there are 0 rig currently in activity at the Barnett gas field. (That doesn't mean 0 production as there are still