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Geology topics

B.B. Ward

Publications and source records attributed to B.B. Ward.

2 recordsLinked to original sources

Ideas and perspectives: A strategic assessment of methane and nitrous oxide measurements in the marine environment

>In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics – namely production, consumption, and net emissions – is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climate-active trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. Fundamental to these efforts is ensuring that the datasets produced by independent scientists are comparable and interoperable. Equally critical is transparent communication within the research community about the technical improvements required to increase our collective understanding of marine CH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB) was organized to enhance dialogue and collaborations pertaining to marine CH4 and N2O. Here, we summarize the outcomes from the workshop to describe the challenges and opportunities for near-future CH4 and N2O research in the marine environment.

Biogeosciences

Selective inhibition of ammonium oxidation and nitrification-linked N2O formation by methyl fluoride and dimethyl ether

Methyl fluoride (CH 3 F) and dimethyl ether (DME) inhibited nitrification in washed-cell suspensions of Nitrosomonas europaea and in a variety of oxygenated soils and sediments. Headspace additions of CH 3 F (10% [vol/vol]) and DME (25% [vol/vol]) fully inhibited NO 2 - and N 2 O production from NH 4 + in incubations of N. europaea , while lower concentrations of these gases resulted in partial inhibition. Oxidation of hydroxylamine (NH 2 OH) by N. europaea and oxidation of NO 2 - by a Nitrobacter sp. were unaffected by CH 3 F or DME. In nitrifying soils, CH 3 F and DME inhibited N 2 O production. In field experiments with surface flux chambers and intact cores, CH 3 F reduced the release of N 2 O from soils to the atmosphere by 20- to 30-fold. Inhibition by CH 3 F also resulted in decreased NO 3 - + NO 2 - levels and increased NH 4 + levels in soils. CH 3 F did not affect patterns of dissimilatory nitrate reduction to ammonia in cell suspensions of a nitrate-respiring bacterium, nor did it affect N 2 O metabolism in denitrifying soils. CH 3 F and DME will be useful in discriminating N 2 O production via nitrification and denitrification when both processes occur and in decoupling these processes by blocking NO 2 - and NO 3 - production.

Applied and Environmental Microbiology