Evaluation of methods for enhancing methane oxidation via increased soil air capacity and nutrient content in simulated landfill soil cover.

Landfill soil covers and methanotrophs therein have potential to act as final sinks of the greenhouse gas methane (CH) generated in landfills, but soil characteristics in landfills might not support methanotrophic activity due to poor soil material selection or mineralisation over time. Hence, our aim was to determine the performance of mineral landfill soil under simulated CH flux and screen methods for elevating the CH elimination capacity (EC) of soil. The methods tested during the column experiment were inorganic fertilisation (nitrate, phosphate, sulphate, copper), decompaction and amelioration of the soil with compost.

Origin and fate of methane in the Eastern Tropical North Pacific oxygen minimum zone.

Oxygen minimum zones (OMZs) contain the largest pools of oceanic methane but its origin and fate are poorly understood. High-resolution (<15 m) water column profiles revealed a 300 m thick layer of elevated methane (20-105 nM) in the anoxic core of the largest OMZ, the Eastern Tropical North Pacific. Sediment core incubations identified a clear benthic methane source where the OMZ meets the continental shelf, between 350 and 650 m, with the flux reflecting the concentration of methane in the overlying anoxic water.

Nitrous oxide as a function of oxygen and archaeal gene abundance in the North Pacific.

Oceanic oxygen minimum zones are strong sources of the potent greenhouse gas NO but its microbial source is unclear. We characterized an exponential response in NO production to decreasing oxygen between 1 and 30 μmol O l within and below the oxycline using NO, a relationship that held along a 550 km offshore transect in the North Pacific. Differences in the overall magnitude of NO production were accounted for by archaeal functional gene abundance.

Methane oxidation potential of boreal landfill cover materials: The governing factors and enhancement by nutrient manipulation.

Methanotrophs inhabiting landfill covers are in a crucial role in mitigating CH4 emissions, but the characteristics of the cover material or ambient temperature do not always enable the maximal CH4 oxidation potential (MOP). This study aimed at identifying the factors governing MOPs of different materials used for constructing biocovers and other cover structures. We also tested whether the activity of methanotrophs could be enhanced at cold temperature (4 and 12°C) by improving the nutrient content (NO3(-), PO4(3-), trace elements) of the cover material.

Riverbed methanotrophy sustained by high carbon conversion efficiency.

Our understanding of the role of freshwaters in the global carbon cycle is being revised, but there is still a lack of data, especially for the cycling of methane, in rivers and streams. Unravelling the role of methanotrophy is key to determining the fate of methane in rivers. Here we focus on the carbon conversion efficiency (CCE) of methanotrophy, that is, how much organic carbon is produced per mole of CH4 oxidised, and how this is influenced by variation in methanotroph communities.