 Xenon is a trace gas in Earth 's atmosphere , occurring at 87 ± 1 parts per billion ( nL / L ) , or approximately 1 part per 11 @.@ 5 million , and is also found as a component in gases emitted from some mineral springs . 
 Xenon <a href='drop_aux' title='1'><mark>is</mark></a>a trace gas in Earth <a href='null_genetive' title='2'><mark>'s</mark></a>atmosphere , occurring at 87 ± 1 parts per billion ( nL / L ) , or approximately 1 part per 11 @.@ 5 million , and is also found as a component in gases emitted from some mineral springs . 
Xenon a trace gas in Earth  atmosphere , occurring at 87 ± 1 parts per billion ( nL / L ) , or approximately 1 part per 11 @.@ 5 million , and is also found as a component in gases emitted from some mineral springs .