Recent developments in applied mathematics and mechanics: theory, experiment and practice. Devoted to the 80th anniversary of academician N.N.Yanenko

Akademgorodok, Novosibirsk, Russia, June 24 - 29, 2001

Abstracts

Novosibirsk participants

Method for determining pollen sedimentation velocity

Istomin V.L., Koutzenogii K.P., Golovko V.V.

Lavrentyev Institute of Hydrodynamics (Novosibirsk)
Institute of Chemical Kinetics and Combustion (Novosibirsk)
Institute of Chemical Kinetics and Combustion (Novosibirsk)

Dispersion of plant pollen in the atmosphere is of great theoretical and practical importance. The role of pollen in plant multiplication is well known. Plant pollen is one of the most mass and widely spread components of bioaerosol and often contains allergens which cause the appearance of pollinoses. The pollen kept in sedimentary rocks is an important bioindicator of climatic changes in the environment in the past. Its role in the transport of some of chemical elements is demonstrated. A space-time change in pollen concentration in the biosphere is much determined by the sedimentation velocity of pollen particles. However, the data on this characteristic are rather scarce due to the complex geometrical form of pollen grains and nonuniform mass distribution over particle volume. As a result, the theoretical calculations of sedimentation velocity are rather difficult. The present paper reports the method and set-up for experimental determination of the sedimentation velocity of individual pollen grains and agglomerates consisting of several particles. The set-up includes both a pulse gas-dynamic generator for spreading pollen powder to form a pollen aerosol cloud and a sedimentator. The experimental data are given on the determination of sedimentation velocity of lycodium and agglomerate particles containing up to five particles (test-object). There is a fair agreement between the values obtained for the sedimentation velocity of an individual particle and the published data. Sedimentation velocities were found not only for lycopodium but also for birch pollen and agglomerate particles containing up to seven individual pollen grains. It is shown that the experimental results are well approximated by the equation

< V_ij> = a_ij + b_iji^1/3 , where i is the number of particles in the agglomerate, j is the pollen type. The set-up can be used to measure the mass of individual pollen grains. The data are presented on the weight of pollen grains of the main pollen types of three plant types determining the structure of bioaerosol pollen component in the Novosibirsk region. The method is given for determining sizes, form, surface, volume, mean density and equivalent aerodynamic diameter. Examples are presented of the use of this approach.

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Note. Abstracts are published in author's edition

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