During August–September 2012, we sampled six hydropower reservoirs in southeastern United States for CO2 and CH4 emissions via three pathways: diffusive emissions from water surface; ebullition in the water column; and losses from dam tailwaters during power generation. Estimates of average areal emission rates of CO2 attributable to the six reservoirs (i.e., reservoir plus tailwater emissions)...

This is the first attempt to budget average current annual carbon (C) and associated greenhouse gas (GHG) exchanges and transfers in a subarctic landscape, the Lake Torneträsk catchment in northern Sweden. This is a heterogeneous area consisting of almost 4000 km2 of mixed heath, birch and pine forest, and mires, lakes and alpine ecosystems. The magnitudes of atmospheric exchange of carbon in t...

Natural open-water pools are a common feature of northern peatlands and are known to be an important source of atmospheric methane (CH4). Pool environmental variables, particularly water chemistry, vegetation community and physical characteristics, have the potential to exert strong controls on carbon cycling in pools. A total of 66 peatland pools were studied across three regions of the UK (no...

The levels of dissolved sulfate and methane are crucial indicators in the geochemical analysis of pore water. Compositional analysis of pore water samples obtained from sea trials was conducted using Raman spectroscopy. It was found that the concentration of SO42- in pore water samples decreases as the depth increases, while the expected Raman signal of methane has not been observed. A possible...

Carbon can be a major constituent of crustal and mantle fluids, occurring both as dissolved ionic species (e.g., carbonate ions or organic acids) and molecular species (e.g., CO2, CO, CH4, and more complex organic compounds). The chemistry of dissolved carbon changes dramatically with pressure (P) and temperature (T). In aqueous fluids at low P and T, molecular carbon gas species such as CO2 an...

Carbon isotope fractionation factors reported for aerobic bacterial oxidation of CH4 ðaCH4–CO2Þ range from 1.003 to 1.039. In a series of experiments designed to monitor changes in the carbon isotopic fractionation of CH4 by Type I and Type II methanotrophic bacteria, we found that the magnitude of fractionation was largely due to the first oxidation step catalyzed by methane monooxygenase (MMO...

The decomposition of deep peat deposits controls the long-term carbon balance of peatlands but is poorly understood with respect to rates and controls. To rectify this deficiency, we estimated in situ dissolved inorganic carbon (DIC) and methane (CH4) production rates from a beaver pond to a central bog dome and related them to organic matter properties, Gibbs free energies of respiration, and ...

Entrapped gas bubbles in peat can alter the buoyancy, storativity, void ratio and expansion/contraction properties of the peat. Moreover, when gas bubbles block water-conducting pores they can significantly reduce saturated hydraulic conductivity and create zones of over-pressuring, perhaps leading to an alteration in the magnitude and direction of groundwater flow and solute transport. Some pr...

Livestock manures are broadly used in agriculture to improve soil quality. However, manure application can increase the availability of organic carbon, thereby facilitating methane (CH4) production. Cattle and swine manures are expected to have different CH4 emission characteristics in rice paddy soil due to the inherent differences in composition as a result of contrasting diets and digestive ...