Seeps of free methane gas escaping the seabed can be found throughout the ocean basins. To understand the role of methane gas seeps in the global carbon cycle—including both gas added to the atmosphere and that which is dissolved and potentially oxidized in the ocean volume—it is important to quantify the amount of methane escaping the seabed. Few large-scale mapping projects of natural methane...

The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes and their phylogenetic diversities in deeply buried marine sediments of the Pacific Ocean Margins. During the ...

Numerous articles have recently reported on gas seepage offshore Svalbard, because the gas emission from these Arctic sediments was thought to result from gas hydrate dissociation, possibly triggered by anthropogenic ocean warming. We report on findings of a much broader seepage area, extending from 74° to 79°, where more than a thousand gas discharge sites were imaged as acoustic flares. The g...

We investigate the effects of methanol and NaCl, which are known as thermodynamic hydrate inhibitors, on the dissociation kinetics of methane hydrate in aqueous solutions by using molecular dynamics simulations. It is shown that the dissociation rate is not constant but changes with time. The dissociation rate in the initial stage is increased by methanol whereas it is decreased by NaCl. This d...

The exceptional catalytic activity of silver for a number of partial oxidation reactions has been known for nearly a century. Despite the wid espread use of silver in heterogeneous catalysis, there still remain unresolved questions about the mechanistic details of reaction. The ethylene epoxidation and formaldehyde synthesis reactions are the two industrially-relevant reactions which have recei...

176 DETERMINING DISSOLVED HYDROGEN, METHANE, AND VINYL CHLORIDE CONCENTRATIONS IN AQUEOUS SOLUTION ON A NANOMOLAR SCALE WITH THE BUBBLE STRIP METHOD D.H. Kampbell, J.T. Wilson, and D.M. McInnes U.S. EPA, National Risk Management Research Laboratory, Subsurface Protection and Remediation Division, P.O. Box 1198, Ada, OK 74820; ManTech Environmental Research Services Corp., East Central Universit...

Fuel ethanol releases can stimulate methanogenesis in impacted aquifers, which could pose an explosion risk if methane migrates into enclosed spaces where ignitable conditions exist. To assess this potential risk, a flux chamber was emplaced on a pilot-scale aquifer exposed to continuous release (21 months) of an ethanol solution (10% v:v) that was introduced 22.5 cm below the water table. Desp...

The super-saturation condition has to be provided to form gas hydrates. Consequently, the prediction of the guest molecule fraction in the aqueous phase is crucial in the study of the gas hydrate kinetics. In the present work, several experiments were carried out in a semi-batch reactor in order to determine the mole fraction of methane and ethane during gas hydrates formation (growth stage...