Hule and Río Cuarto are maar lakes located 11 and 18 km N of Poás volcano along a 27 km long fracture zone, in the Central Volcanic Range of Costa Rica. Both lakes are characterized by a stable thermic and chemical stratification and recently they were affected by fish killing events likely related to the uprising of deep anoxic waters to the surface caused by rollover phenomena. The vertical p...

Large amounts of CH4 in the form of solid hydrates are stored on continental margins and in permafrost regions. If these CH4 hydrates could be converted into CO2 hydrates, they would serve double duty as CH4 sources and CO2 storage sites. We explore here the swapping phenomenon occurring in structure I (sI) and structure II (sII) CH4 hydrate deposits through spectroscopic analyses and its poten...

Abstract. Tropical ecosystems contribute significantly to global emissions of methane (CH4), and landscape topography influences the rate CH4 from wet tropical forest soils. However, extreme events such as drought can alter normal topographic patterns emissions. Here we explain dynamics during conditions across a catena in Luquillo Experimental Forest, Puerto Rico. Valley soils served major sou...

Small water bodies including drainage ditches can be hotspots for methane (CH4) emissions from peatlands. We assessed the CH4 of a drained and rewetted temperate fen managed unmanaged over course 2.5 years, covering three vegetation periods. Ditch in were significantly higher than fen. In contributed up to 91% annual budget, despite only 1.5% area. solely made ditch emissions. When uptake by pe...

We report dissolved CO2, CH4 and N2O concentrations in two large East African lakes, Edward (surface area 2,325 km2, average depth of 37 m) George 273 2 m). Lake showed modest seasonal spatial variations, lower partial pressure CO2 (pCO2) (26 ± 16 ppm, mean standard deviation), (234 208 nmol/L) saturation levels (%N2O) (80 9 %) than (404 145 357 483 nmol/L, 139 222 %). Surface waters both lakes...

Atmospheric methane (CH4) is the second strongest greenhouse gas and it is emitted to the atmosphere naturally by different sources. It is crucial to define the dimension of these natural emissions in order to forecast changes in atmospheric CH4 mixing ratio in future scenarios. However, CH4 emissions by seagrass ecosystems in shallow marine coastal systems have been neglected although their gl...

Hydrocarbons such as CH4 are known to be formed through the Fischer-Tropsch or Sabatier type reactions in hydrothermal systems usually at temperatures above 100°C. Weathering of olivine is sometimes suggested to account for abiotic formation of CH4 through its redox lowering and water splitting properties. Knowledge about the CH4 and H2 formation processes at low temperatures is important for t...

We found unprecedentedly high abundances of microbially produced CH4 in the anoxic deep waters of Lake Untersee, an oligotrophic, perennially ice-covered Antarctic freshwater lake. The maximum CH4 concentration (approaching 21.8 6 1.4 mmol L21) is one of the highest observed so far in a natural aquatic ecosystem. Although surficial lake sediments are the predominant source of CH4 in Lake Unters...

The laser methane detector (LMD) has been proposed as a method to characterize enteric methane (CH4) emissions from animals in a natural environment. To validate LMD use, its CH4 outputs (LMD-CH4), were compared against CH4 measured with respiration chambers (chamber-CH4). The LMD was used to measure CH4 concentration (μL/L) in the exhaled air of 24 lactating ewes and 72 finishing steers. In ew...

Changes in the hydrological conditions of coastal wetlands may potentially affect the role of wetlands in the methane (CH4) cycle. In this study, the CH4 production potential and emissions from restored coastal reed wetlands at different water levels were examined in eastern China at a field scale in two phenological seasons. Results showed that the total CH4 flux from reeds at various water le...