Development of an Atmosphere-Soil-Vegetation Model for Investigation of Radioactive Materials Transport in the Terrestrial Biosphere

Abstract

In order to investigate the transport of radionuclides in the terrestrial biosphere we have developed a one-dimensional numerical model named SOLVEG that predicts the transfer of water, heat, and gaseous and particulate matters in the atmosphere-vegetation-soil system. SOLVEG represents the atmosphere, the soil, and the vegetation as an aggregation of several layers. Basic equations used in the model are solved using the finite difference method. Most of the predicted variables are interrelated with the source/sink terms of momentum, water, heat, gases, and particles based on mathematically described biophysical processes in atmosphere, soil and vegetation. SOLVEG can calculate the deposition of gaseous compounds and particulates, including fog droplets, at each canopy layer. Performance tests of SOLVEG were carried out with several observational sites. SOLVEG predicted well the observed temporal changes in water vapor and CO 2 fluxes, and the deposition velocity of O 3 and SO 2 at the vegetation surface, mainly driven by photosynthesis. SOLVEG also reproduced measured fluxes of fog droplets (diameter > 1 m) and of fine aerosols (diameter < 1 m) over a coniferous forest.

Development of the RAQM2 aerosol chemical transport model and predictions of the Northeast Asian aerosol mass, size, chemistry, and mixing type

“…For example, the size-segregated dry deposition velocity for the vegetative surface decreased and increased by one order of magnitude within the 0.1-and 1-µm-diameter range, which is comparable to the performance of the detailed multi-layer particle deposition model by Katata et al (2011). For ground and water surfaces, a good agreement was found between the modified model calculations and the observations from the literature, as shown in Petroff and Zhang (2010).…”

“…Gas chemistry 72 species and 214 reactions (SAPRC99; Carter, 2000) SOA chemistry Edney et al (2007) Liquid chemistry Walcek and Taylor (1986); Carlton et al ( 2007) New particle formation Kuang et al (2008) Aerosol dynamics (condensation, evaporation, coagulation) This study and MADMS (Kajino, 2011) Surface gas-aerosol equilibrium of inorganic and organic compounds ISORROPIA2 (Fountoukis and Nenes, 2007), Edney et al (2007) Dry deposition This study, Zhang et al (2001Zhang et al ( , 2003, and Katata et al (2008Katata et al ( , 2011 CCN activation Abdul-Razzak and Ghan (2000) IN activation Lohmann and Diehl (2010) Grid-scale cloud microphysics Lin et al (1983) Collision of aerosol with grid-scale rain, snow and graupel droplets…”

“…(A44) to (A48). With regard to calculating the dry deposition for particles, however, the original parameterization of surface resistance by Zhang et al (2001) used by Kajino and Kondo (2011) was modified based on comparisons by more recent works (Katata et al, 2008(Katata et al, , 2011Petroff and Zhang, 2010) using observational data to improve the prediction Atmos. Chem.…”

“…(14) and (16) in Katata et al, 2011), respectively, were also used for vegetative surfaces. Those formulations were verified using the flux data for fine aerosols (< 1 µm) over the coniferous forest in Katata et al (2011).…”

Estimation of dry deposition velocities of radionuclides released by the accident at the Fukushima Dai-ichi Nuclear Power Plant

“…The process of dry deposition is driven by a variety of physical, chemical and biological factors. Further complication arises from the fact that radionuclides, when released into the atmosphere, exist in various chemical and physical states [2].…”