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  • 1
    Electronic Resource
    Electronic Resource
    Boundary layer properties of highly dissected leaves: an investigation using an electrochemical fluid tunnel (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 13 (1990), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. A method for modelling heat and mass transfer by diffusion-controlled electrode reactions in a fluid tunnel is described. In this procedure, a nickelplated leaf functions as a test electrode, and the convective transfer of ions to the leaf cathode in an electrolyte-filled flow tunnel is measured as a function of flow rate. The method permits the simulation of water vapour and heat transfer, and in particular, the determination of boundary layer conductances, by analogy with observed ion transfer. The approach is applicable to many problems in modelling heat and mass transfer between leaves and their surroundings, and is especially useful in examining the properties of leaves in which surface characteristics or overall shape are complex. Using this method, the properties of the highly dissected leaves of Achillea lanulosa with regard to forced convection were investigated. The leaves showed high transfer conductances, indicating that the effective unit of heat transfer was probably the individual leaf subelements. Conductances tended to be greater and effective characteristic dimensions smaller for the larger, more open leaves of a lower altitude population in contrast with leaves from high altitude plants. While the results provide insight into the properties of these complex leaf shapes, difficulties in interpreting the findings are discussed, and a number of exploratory approaches are suggested for data analysis and interpretation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1990.tb01094.x
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  • 2
    Electronic Resource
    Electronic Resource
    Aircraft measurements of CO2 exchange over various ecosystems (1984)
    Springer
    Boundary layer meteorology 29 (1984), S. 167-183 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The National Aeronautical Establishment's Twin Otter Atmospheric Research Aircraft has been equipped with open-path CO2 analyzers in order to obtain estimates of CO2 exchange over a corn field, a forest and a lake using the eddy correlation technique. On the 18th of August 1980, mean uptakes obtained over corn and forest were 12 and 8 kg CO2 ha-1 hr-1, respectively. On the 28th of August, mean uptakes obtained over corn, forest and the lake were 36, 14, and 1 kg CO2 ha-1 hr-1, respectively. The data are discussed in the light of general conditions on the two days.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00206829
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  • 3
    Electronic Resource
    Electronic Resource
    Studies of forced-convection heat and mass transfer of fluttering realistic leaf models (1972)
    Springer
    Boundary layer meteorology 2 (1972), S. 263-274 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The forced-convection mass transfer - and by analogy, heat transfer - of various realistic leaf models at Reynolds numbers 2 x 103〈Re〈4 x 104 was studied with an electrochemical method. The results are compared with similar measurements on plates and with transfer coefficients calculated from the laminar boundary-layer theory. In this way the validity of the commonly-used analytical expressions which represent the leaf by a rigid plate and neglect the effects of leaf curvature, fluttering, surface roughness and fluid turbulence, can be tested. The measurements show that for fluttering single leaves, the convective mass-transfer coefficients must be expected to be higher by a factor of 1.4 ± 0.1 than the ones calculated for rigid plates of equal size and shape. For a leaf in a crop, the increase might be as high as a factor of 2. The high transfer coefficients measured for elements of cedar foliage are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02184768
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  • 4
    Electronic Resource
    Electronic Resource
    Footprint prediction of scalar fluxes from analytical solutions of the diffusion equation (1990)
    Springer
    Boundary layer meteorology 50 (1990), S. 355-373 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The use of analytical solutions of the diffusion equation for ‘footprint prediction’ is explored. Quantitative information about the ‘footprint’, i.e., the upwind area most likely to affect a downwind flux measurement at a given height z, is essential when flux measurements from different platforms, particularly airborne ones, are compared. Analytical predictions are evaluated against numerical Lagrangian trajectory simulations which are detailed in a companion paper (Leclerc and Thurtell, 1990). For neutral stability, the structurally simple solutions proposed by Gash (1986) are shown to be capable of satisfactory approximation to numerical simulations over a wide range of heights, zero displacements and roughness lengths. Until more sophisticated practical solutions become available, it is suggested that apparent limitations in the validity of some assumptions underlying the Gash solutions for the case of very large surface roughness (forests) and tentative application of the solutions to cases of small thermal instability be dealt with by semi-empirical adjustment of the ratio of horizontal wind to friction velocity. An upper limit of validity of these solutions for z has yet to be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00120530
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  • 5
    Electronic Resource
    Electronic Resource
    Book reviews (1990)
    Springer
    Boundary layer meteorology 53 (1990), S. 297-302 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00154445
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  • 6
    Electronic Resource
    Electronic Resource
    Model experiments on free-convection heat and mass transfer of leaves and plant elements (1973)
    Springer
    Boundary layer meteorology 3 (1973), S. 454-467 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Effects of orientation, shape, and surface structure on the free convection mass transfer of plates, leaf- and plant-models were studied in an electrolytic system. The results were extrapolated to the transfer of heat and mass in air, in an effort to predict realistic boundary-layer transfer coefficients for leaves and plant-like surfaces. Flow visualization complemented the investigation. The results indicate that increases in transfer of 50% over that of a vertical plate are possible for non-vertical rough leaves, but that a 25% increase is a more reasonable estimate for an ‘average plant’. Evidence is also presented that more reliable caluclations of the transfer properties of pine needles are obtained if the needles are approximated by vertical cylinders, rather than by horizontal ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01034988
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  • 7
    Electronic Resource
    Electronic Resource
    An evaluation of aircraft flux measurements of CO2, water vapor and sensible heat (1989)
    Springer
    Boundary layer meteorology 47 (1989), S. 55-69 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Ground-based flux measurements of carbon dioxide and water vapor integrate physiological processes taking place on a field scale. Aircraft flux measurements have recently been undertaken to attempt to widen the scope of applicability of such measurements. However, because of the intermittency of turbulent transfer, flux measurements must be averaged over long periods of time or long distances to give reproducible results. This requirement makes it difficult to relate aircraft flux measurements to local surface processes. Flux measurements of CO2, latent and sensible heat obtained from repeated passes in four directions and at three elevations over a homogeneous wheat-growing area are compared with ground-based measurements. Averages based on four runs of 4 km in length gave results consistent with ground-based measurements. The largest percentage differences were in the sensible heat flux. Cospectral analyses showed no significant high frequency losses for the data from flight levels of 25 and 50 m, but an underestimation of approximately 10% resulted at 10 m. Flight direction with respect to wind direction was relatively unimportant at 10 and 25 m but some effects were observed at 50 m. It was also shown that at 25 m, over a relatively smooth and homogeneous surface, the means of either three or four runs 4 km in length were similar to the means of 12–16 km runs. This confirms that at this altitude, most of the flux contribution is contained at wavelengths less than 4 km and that the mean of 3 to 4 passes accounts for most of the intermittency of turbulent transfer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122322
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  • 8
    Electronic Resource
    Electronic Resource
    Trace metal contamination in and on Balsam fir (abies Balsamea (L) Mill.) Foliage in southern Quebec, Canada (1995)
    Springer
    Water, air & soil pollution 81 (1995), S. 175-191 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Atmospheric trace metal contamination in and on forest foliage in southern Quebec has been investigated. Washed and unwashed foliage of Balsam fir from seven sampling sites with different elevation were analyzed by NAA. Metal element concentrations in needles were generally well below the suggested levels of potential phytotoxicity, except for Mn. At three rural mountain sampling locations, Mn concentration exceed 600 μg/g in washed and unwashed needles. The variability of metal concentrations between individual trees at a given site showed the expected element-specific differences, with most CV's 〈 50%. The variation of metal deposits on needle surfaces (ng/cm2) with elevation and sampling site depended on the element concerned. The input of Al, As, Cr, La, Sb, Sc, Sm, and V, accompanying Fe in deposits on the foliage surface, may mainly come from atmospheric deposition in the form of soil dust and air pollution. Wet deposition samples from Roundtop Mountain suggest cloud immersion as a significant trace element deposition pathway in high elevation forest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00477264
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  • 9
    Electronic Resource
    Electronic Resource
    Nutrient leaching from dormant trees at an elevated site (1989)
    Springer
    Water, air & soil pollution 45 (1989), S. 253-264 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Observations are presented on ion concentration in winter deposits to coniferous and deciduous trees at an elevated site (860 m). Such sites, with persistent snow and ice cover and considerable deposition of atmospheric pollutants, are common in Eastern Canada and the North-Eastern U.S. Spot samples at a given sampling date and samples of total deposits accumulated over extended periods of time were taken during the winters of 1986–87 and 1987–88. Samples were analyzed for pH and the major anion and cations. Results of spot samples were similar between different sampling times (and years) for deposits on balsam fir but variable for those on branches and twigs of deciduous trees (birch, choke cherry). The chemistries of snow on the ground and snow on trees not in contact with foliage or branches were found not to be significantly different statistically (p〈0.05). However, significant differences exist between concentrations of nutrient ions in snow and ice with and without contact with biological elements of coniferous and deciduous trees. This indicates occurrence of nutrient leaching during winter conditions, leading to possibly non-negligent nutrient stress for K− and Mg−. Based on spot and cumulative samples for balsam fir, and correcting for possible contributions from dry deposition, the contribution from leaching in winter deposits on balsam fir foliage has been estimated at 26, 14 and 9 μeq L−1, for K+, Ca++ and Mg++, respectively. With approximate estimates of stand characteristics and precipitation loading at the sampling sites, these figures represent 90/c, 1% and 8%, respectively, of the estimated annual growth component of the stand for K+, Ca++ and Mg++ This indicates the possibility of non-negligible nutrient stress for K+ and Mg+ during winter conditions at the given site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00283456
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  • 10
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    Uptake and Translocation Studies in Balsam Fir Seedlings with 54 Mn and 65 Zn Radioisotopes Applied to Soil Surfaces (1996)
    Wiley
    Details
    Publication Date: 1996-01-01
    Print ISSN: 0047-2425
    Electronic ISSN: 1537-2537
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley
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