Scaling carbon dioxide and water vapour exchange from leaf to canopy in a deciduous forest. II. Model testing and application

Abstract. We present results from a study of canopy-atmosphere fluxes of carbon dioxide from 2007 to 2009 above a site in Wytham Woods, an ancient temperate broadleaved deciduous forest in southern England. Gap-filled net ecosystem exchange (NEE) data were partitioned into gross primary productivity (GPP) and ecosystem respiration (Re) and analysed on daily, monthly and annual timescales. Over the continuous 24 month study period annual GPP was estimated to be 21.1 Mg C ha−1 yr−1 and Re to be 19.8 Mg C ha−1 yr−1; net ecosystem productivity (NEP) was 1.2 Mg C ha−1 yr−1. These estimates were compared with independent bottom-up estimates derived from net primary productivity (NPP) and flux chamber measurements recorded at a plot within the flux footprint in 2008 (GPP = 26.5 ± 6.8 Mg C ha−1 yr−1, Re = 24.8 ± 6.8 Mg C ha−1 yr−1, biomass increment = ~1.7 Mg C ha−1 yr−1). Over the two years the difference in seasonal NEP was predominantly caused by changes in ecosystem respiration, whereas GPP remained similar for equivalent months in different years. Although solar radiation was the largest influence on daily values of CO2 fluxes (R2 = 0.53 for the summer months for a linear regression), variation in Re appeared to be driven by temperature. Our findings suggest that this ancient woodland site is currently a substantial sink for carbon, resulting from continued growth that is probably a legacy of past management practices abandoned over 40 years ago. Our GPP and Re values are generally higher than other broadleaved temperate deciduous woodlands and may represent the influence of the UK's maritime climate, or the particular species composition of this site. The carbon sink value of Wytham Woods supports the protection and management of temperate deciduous woodlands (including those managed for conservation rather than silvicultural objectives) as a strategy to mitigate atmospheric carbon dioxide increases.

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Performance Evaluation of Design AD System Biogas Purification Filter

International Journal of Mathematical Engineering and Management Sciences ◽

10.33889/ijmems.2018.3.1-003 ◽

2018 ◽

Vol 3 (1) ◽

pp. 17-27 ◽

Cited By ~ 1

Author(s):

Ejiroghene Kelly Orhorhoro ◽

Oghenero Wilson Orhorhoro ◽

Eruero Victor Atumah

Keyword(s):

Carbon Dioxide ◽

Performance Evaluation ◽

Water Vapour ◽

Hydrogen Sulphide ◽

Activated Charcoal ◽

Preliminary Test ◽

Decision Matrix ◽

Percentage Composition ◽

Detail Design ◽

Biogas Purification

Biogas purification which is the removal of impurities so as to improve the efficiency of gas produced, ensure the safety of end users and prolong the life of the equipment cannot be neglected. This paper is focused on the design and performance evaluation of AD system biogas purification filter. Three different conceptual designs were generated from possible design consideration, feasibility study and preliminary test and with the help of decision matrix; the best conceptual design was selected from which the purification filter was fabricated. The selected concept for detail design was a transparent polyethene cylindrical purification filter fitted with local iron sponge containing activated charcoal and local potash. The reagents were arranged in this order; local potash for the removal of water vapour and carbon dioxide followed by activated charcoal which serves as a purifying agent for hydrogen sulphide. The results obtained showed reduction in percentage composition of hydrogen sulphide (H2S), carbon dioxide, and water vapour. On the other hand, there was an increase in percentage composition of methane (CH4) which is an indication of improvement in methane production after purification. The outcomes of the results obtained were satisfactory and the combination of local potash and activated charcoal was adequate for biogas purification.

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The Diffusion of Carbon Dioxide and Water Vapour through Stomata

Journal of Experimental Botany ◽

10.1093/jxb/25.5.927 ◽

1974 ◽

Vol 25 (5) ◽

pp. 927-936 ◽

Cited By ~ 60

Author(s):

P. D. JARMAN

Keyword(s):

Carbon Dioxide ◽

Water Vapour

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An Evaluation of Five Carbon Dioxide Analysers for use in the Operating Theatre and Intensive Care Unit

Anaesthesia and Intensive Care ◽

10.1177/0310057x8701500216 ◽

1987 ◽

Vol 15 (2) ◽

pp. 212-216 ◽

Cited By ~ 7

Author(s):

D. G. Selby ◽

A. H. Ilsley ◽

W. B. Runciman

Keyword(s):

Carbon Dioxide ◽

Intensive Care Unit ◽

Intensive Care ◽

Water Vapour ◽

Operating Theatre ◽

Main Stream ◽

Time Stability ◽

Side Stream ◽

Stream Sampling ◽

Available Carbon

Five commercially available carbon dioxide analysers were assessed with respect to accuracy, response time, stability, the effect of water vapour and the effect of rebreathing. Two side-stream sampling analysers (Datex Normocap and Engstrom Eliza) and one main-stream sampling analyser (Hewlett-Packard Capnoshot) were found to be satisfactory for use both in the operating theatre and intensive care unit. The Instrumentation Laboratory (IL) 200, a side-stream monitor, performed satisfactorily but neither it nor the Siemens Sirecust 404, a main-stream monitor, has the facility to compensate for the presence of nitrous oxide. The Siemens analyser, in the form tested, could not be recommended for clinical use, as it was less accurate than the other monitors, could not detect rebreathing, and was subject to fluctuations when used with gas mixtures saturated with water vapour.

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