Chapter 4, Problem 5CHI

In the chapter opening case study, we focus on the production of methane by archaea living in the rumens of domesticated ruminant animals. However, there are many other sources of methane besides livestock. These include wild ruminants, the anoxic soils of rice paddies, and deforestation. There is considerable interest in more precisely measuring the output of methane by all these sources, yet current methods have many drawbacks. Some are laborious; some have a high degree of variability; others can only be used in highly controlled environments. In 2011 a group of scientists reported their attempts to correlate methane production with the amount of archaeol in the feces of cattle. They also determined archaeol levels resulting from different feeding regimens. Archaeol is a glycerol diether that can be measured by chemical procedures such as gas chromatography. What assumption did the scientists make when they chose to measure archaeol? Why did they choose to measure a glycerol diether rather than a diglycerol tetraether in their study? Suggest one other application of this method to better understand methane release into the atmosphere.