Skip to main content
U.S. flag

An official website of the United States government

Nitrogen, phosphorus, and suspended-sediment loads and trends measured at the Chesapeake Bay Nontidal Network stations: Water years 1985-2016

December 11, 2017

Degassing thermal features at Yellowstone National Park include spectacular geysers, roiling hot springs, bubbling mud pots, fumaroles, frying pans, and areas of passive degassing characterized by steaming ground. Most of these features are readily identified by visible clouds of steam that are occasionally accompanied by a strong rotten egg odor from emissions of hydrogen sulfide gas. Gas compositions typically are greater than 90% carbon dioxide with lesser amounts of helium, hydrogen, hydrogen sulfide, methane, nitrogen and other trace components. The composition of the gas and relative amounts of gas and steam relate both to the type of feature as well as the geographic location within the park. In 2003 we began a long-term field study of Yellowstone gases with a goal of obtaining complete chemical analyses from a variety of features from all areas of the park. Results from samples collected through 2012 are published in numerous journal articles and 2 data releases (see below). Synthesis of these studies enabled us to delineate areas dominated by crustal and magmatic gas sources and to tease out information on additional sources of gas related to sedimentary and metamorphic processes. This report compiles the early gas data and new gas and water data from samples collected in 2014 and 2015. In total there are 190 analyses of gas collected in evacuated bottles containing sodium hydroxide, 30 analyses of gas collected in dry evacuated bottles, and 62 water analyses from thermal and non-thermal features. Some of the analyses represent replicate samples collected in different bottles on the same day, others are samples collected from the same location in different years, and some sites were only sampled once. The analytical results include major and trace element chemistry for the gases and waters and isotope values for water and steam (d18O, dD), carbon dioxide (d13C), methane (d13C), helium (3He/4He), neon (20Ne/22Ne and 21Ne/22Ne), and argon (38Ar/36Ar and 40Ar/36Ar). All data in this report supersede previously published analyses. The gas and water data are presented in 3 tables and are keyed to a group number, from 1 through 20. Samples in groups 2 through 10 and 12 through 20 tend to be in close proximity. Group 11 includes samples from general locations across Eastern Yellowstone. Samples keyed to group 1 (miscellaneous) are not co-located. The reader is directed to early publications for details on sampling and analytical methods and for in depth discussions regarding interpretations of the gas data.