Atmospheric constraints on global emissions of methane from plants

We investigate whether a recently proposed large source of CH4 from vegetation can be reconciled with atmospheric measurements. Atmospheric transport model simulations with and without vegetation emissions are compared with background CH4, delta C-13-CH4 and satellite measurements. For present - day CH4 we derive an upper limit to the newly discovered source of 125 Tg CH4 yr(-1). Analysis of preindustrial CH4, however, points to 85 Tg CH4 yr(-1) as a more plausible limit. Model calculations with and without vegetation emissions show strikingly similar results at background surface monitoring sites, indicating that these measurements are rather insensitive to CH4 from plants. Simulations with 125 Tg CH4 yr(-1) vegetation emissions can explain up to 50% of the previously reported unexpectedly high CH4 column abundances over tropical forests observed by SCIAMACHY. Our results confirm the potential importance of vegetation emissions, and call for further research

Effect of UV radiation and temperature on the emission of methane from plant biomass and structural components

The recently reported finding that plant matter and living plants produce significant amounts of the important greenhouse gas methane under aerobic conditions has led to an intense scientific and public controversy. Whereas some studies question the up-scaling method that was used to estimate the global source strength, others have suggested that experimental artifacts could have caused the reported signals, and two studies, one based on isotope labeling, have recently reported the absence of CH<sub>4</sub> emissions from plants. Here we show – using several independent experimental analysis techniques – that dry and detached fresh plant matter, as well as several structural plant components, emit significant amounts of methane upon irradiation with UV light and/or heating. Emissions from UV irradiation are almost instantaneous, indicating a direct photochemical process. Long-time irradiation experiments demonstrate that the size of the CH<sub>4</sub> producing reservoir is large, exceeding potential interferences from degassing or desorption processes by several orders of magnitude. A dry leaf of a pure <sup>13</sup>C plant produces <sup>13</sup>CH<sub>4</sub> at a similar rate as dry leaves of non-labeled plants produce non-labeled methane

Результати ексгумації останків загиблих солдатів у центрі селища Цумань у 2010 р.

В статті висвітлюються результати археологічних досліджень Цуманської рятівної експедицією ДП « Волинські Старожитності» ДП НДЦ ОАСУ ІА НАН України, проведених у червні 2010 р. на місцезнаходженні останків солдатів Червоної армії часів Другої світової війни у центрі селища Цумань Ківерцівського району Волинської області

Helium-oxygen reduces the production of carbon dioxide during weaning from mechanical ventilation

<p>Abstract</p> <p>Background</p> <p>Prolonged weaning from mechanical ventilation has a major impact on ICU bed occupancy and patient outcome, and has significant cost implications.</p> <p>There is evidence in patients around the period of extubation that helium-oxygen leads to a reduction in the work of breathing. Therefore breathing helium-oxygen during weaning may be a useful adjunct to facilitate weaning. We hypothesised that breathing helium-oxygen would reduce carbon dioxide production during the weaning phase of mechanical ventilation.</p> <p>Materials/patients and methods</p> <p>We performed a prospective randomised controlled single blinded cross-over trial on 19 adult intensive care patients without significant airways disease who fulfilled criteria for weaning with CPAP. Patients were randomised to helium-oxygen and air-oxygen delivered during a 2 hour period of CPAP ventilation. Carbon dioxide production (VCO₂) was measured using a near patient main stream infrared carbon dioxide sensor and fixed orifice pneumotachograph.</p> <p>Results</p> <p>Compared to air-oxygen, helium-oxygen significantly decreased VCO₂production at the end of the 2 hour period of CPAP ventilation; there was a mean difference in CO₂production of 48.9 ml/min (95% CI 18.7-79.2 p = 0.003) between the groups. There were no significant differences in other respiratory and haemodynamic parameters.</p> <p>Conclusion</p> <p>This study shows that breathing a helium-oxygen mixture during weaning reduces carbon dioxide production. This physiological study supports the need for a clinical trial of helium-oxygen mixture during the weaning phase of mechanical ventilation with duration of weaning as the primary outcome.</p> <p>Trial registration</p> <p>ISRCTN56470948</p

Ground-based FTIR measurements of O3- and climate-related gases in the free troposphere and lower stratosphere

In the frame of the EC project UFTIR (Time series of Upper Free Troposphere observations from a European ground-based FTIR network), a common strategy for an optimal determination of the chemical composition in the free troposphere and lower stratosphere with ground-based Fourier-transform infrared (FTIR) spectrometers is being developed. The project focuses on 6 target species that are O3, CO, CH4, N2O, C2H6 and CHClF2 (HCFC-22). The strategy consists in selecting the most appropriate parameters to retrieve vertical concentration profiles from solar FTIR spectra. Among the important parameters are the spectral microwindows: they have been optimised to maximise the information content and to minimize the influence of poorly known spectroscopic data and interfering species

Methane Feedbacks to the Global Climate System in a Warmer World

Methane (CH4) is produced in many natural systems that are vulnerable to change under a warming climate, yet current CH4 budgets, as well as future shifts in CH4 emissions, have high uncertainties. Climate change has the potential to increase CH4 emissions from critical systems such as wetlands, marine and freshwater systems, permafrost, and methane hydrates, through shifts in temperature, hydrology, vegetation, landscape disturbance, and sea level rise. Increased CH4 emissions from these systems would in turn induce further climate change, resulting in a positive climate feedback. Here we synthesize biological, geochemical, and physically focused CH4 climate feedback literature, bringing together the key findings of these disciplines. We discuss environment-specific feedback processes, including the microbial, physical, and geochemical interlinkages and the timescales on which they operate, and present the current state of knowledge of CH4 climate feedbacks in the immediate and distant future. The important linkages between microbial activity and climate warming are discussed with the aim to better constrain the sensitivity of the CH4 cycle to future climate predictions. We determine that wetlands will form the majority of the CH4 climate feedback up to 2100. Beyond this timescale, CH4 emissions from marine and freshwater systems and permafrost environments could become more important. Significant CH4 emissions to the atmosphere from the dissociation of methane hydrates are not expected in the near future. Our key findings highlight the importance of quantifying whether CH4 consumption can counterbalance CH4 production under future climate scenarios

Does the Optimal Size of a Fish Stock Increase with Environmental Uncertainties?

We analyze the effect of environmental uncertainties on optimal fishery management in a bio-economic fishery model. Unlike most of the literature on resource economics, but in line with ecological models, we allow the different biological processes of survival and recruitment to be affected differently by environmental uncertainties. We show that the overall effect of uncertainty on the optimal size of a fish stock is ambiguous, depending on the prudence of the value function. For the case of a risk-neutral fishery manager, the overall effect depends on the relative magnitude of two opposing effects, the 'convex-cost effect' and the 'gambling effect'. We apply the analysis to the Baltic cod and the North Sea herring fisheries, concluding that for risk neutral agents the net effect of environmental uncertainties on the optimal size of these fish stocks is negative, albeit small in absolute value. Under risk aversion, the effect on optimal stock size is positive for sufficiently high coefficients of constant relative risk aversion

Effect of two-step hygiene management on the prevention of nosocomial influenza in a season with high influenza activity

SummaryBackgroundRapid identification of patients infected with influenza virus, precise case definition and strict hygiene measures are important for the prevention of nosocomial transmission.AimTo prove the usefulness of a case definition for rapid identification of patients with influenza and to investigate the effect of two-step hygiene management, including the continuous use of surgical masks by hospital staff, on the rate of nosocomial infections.MethodsAll patients hospitalized between January and March 2015 with suspected influenza were enrolled. Real-time polymerase chain reaction testing for influenza was performed. Infected patients were managed according to the national hygiene guidelines, including the use of surgical masks by hospital staff during close contact with infected patients. When influenza activity increased, the continuous use of surgical masks by hospital staff was implemented as an add-on measure.FindingsMost patients enrolled in this study were elderly (N=212, mean age 75 years). Frequency of cough was the only clinical parameter of respiratory infection that differed between influenza-negative and influenza-positive patients. Compared with the targeted use of surgical masks during close contact with infected patients, the continuous use of surgical masks for the entire working shift resulted in a reduction of nosocomial infections from 31% to 16%, respectively (P<0.01).ConclusionDiscrimination between influenza A and other respiratory infections in elderly hospitalized patients was not possible based on clinical characteristics. With regard to hygiene management, the continuous use of surgical masks by hospital staff seems to be effective for the prevention of nosocomial infections