A significant unknown in our understanding of climate change and the chemical state of the ocean involves oceanic methane (CH4). Numerous studies have conducted measurements of the sea-air flux of methane. These studies were conducted primarily to assess the extent to which the massive reservoir of methane in ocean sediments is contributing to the atmospheric greenhouse gas budget. Most of these studies have relied on collecting discrete surface water samples and historic measurements of atmospheric methane concentration and meteorological data.
This EAGER seeks to to design and test a small portable unit for assessing the sea-air flux of methane in natural water systems including the ocean, estuaries, and lakes. This instrument is based on the small footprint design of the pCO2 systems developed for use on volunteer observing ships and research vessels and described by Pierrot et al. [2009]. One of the modifications to the pCO2 system design will be the simultaneous monitoring of both the air and the recirculated headspace from the equilibrator rather than alternating the analysis and losing time to flushing out the cells.
Broader Impacts
The potential benefit to ocean community of having an accurate quantification of methane source strengths is important to future climate modeling. A graduate student from an underrepresented group in STEM fields will be trained during the development and field testing of this new instrument.
The goal of this award is to develop a portable, user-friendly system to measure the air-water flux of methane and carbon dioxide. Methane and carbon dioxide are greenhouse gases and marine and terrestrial aquatic environments are large reservoirs of these gases. Measuring the transfer of these greenhouse gases between the atmosphere and these aqueous reservoirs enables the understanding of what roles these systems play in global climate change. Previous techniques have been established to measure the air-water transfer of these gases, however, they are both labor intensive as well as require dedicated and specialized scientists to conduct these analyses. The project recognizes the diversity of aqueous environments that span Earth and the massive greenhouse gas reservoirs below their water surfaces; a portable, user-frieldly system was developed who's design will be disseminated to the larger scientific community. The development and dissemination of this system will enable the efficient global characterization of these greenhouse gas fluxes. This system was first developed in the laboratory using seawater equilibrators for the analysis of dissolved gas concentration in surface waters. This system was tested during 2 expeditions throughout the state of Alaska during 2011 and 2012. An updated system was then developed building upon the findings from these two research expeditions. The updated system contains a dissolved gas extraction system for the rapid analysis of dissolved gas concentrations. This updated system was intercompared againsted the original system during two oceanographic expeditions: August 2012 in the Gulf of Mexico on the R/V Cape Hatteras and July 2014 in the North Atlantic Ocean on the R/V Endeavor. Based on the results of these laboratory and field experiments, final system designs are being prepared for dissemination to the scientific community.
