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Ota, Masakazu; Terada, Hiroaki; Hasegawa, Hidenao*; Kakiuchi, Hideki*
Science of the Total Environment, 704, p.135319_1 - 135319_15, 2020/02
Times Cited Count:6 Percentile:29.22(Environmental Sciences)Land-surface transfers of I are modeled and incorporated into a land-surface model (SOLVEG-II), and the model was applied to the observed transfer of I at a vegetated field impacted by atmospheric releases of I from Rokkasho reprocessing plant during 2007 to investigate the importance of each I-transfer pathway. The model calculation revealed that contamination of leaves of wild bamboo grasses was mostly caused by foliar adsorption of I (81%) induced via wet deposition of I. Wet deposition of I was the main I-input to the soil, ten-fold the dry deposition of I; however, the deposition of I during 2007 was only 2% of the model-assumed I that pre-existed in the soil; indicating the importance of long-term accumulation of I in soils. The model calculation also revealed that root uptake of I, not methylation, control the long-term turnover of soil I.
Ota, Masakazu; Tanaka, Taku*
Journal of Environmental Radioactivity, 201, p.5 - 18, 2019/05
Times Cited Count:4 Percentile:16.44(Environmental Sciences)CH released from deep underground radioactive waste disposal facilities can be a belowground source of CO owing to microbial oxidation of CH to CO in soils. Environmental C models assume that the transfer of CO from soil to plant occurs via foliar uptake of CO. Nevertheless, the importance of CO root uptake is not well understood. In the present study, belowground transport and oxidation of CH were modeled and incorporated into an existing land surface CO model (SOLVEG-II) to assess the importance of root uptake on CO transfer to plants. Performance of the model in calculating the belowground dynamics of CH was validated by simulating a field experiment of CH injection into subsoil. The model was then applied to C transfer in a hypothetical ecosystem impacted by continuous CH input from the water table (bottom of one-meter thick soil). In a shallowly rooted ecosystem with rooting depth of 11 cm, foliar uptake of CO was significant, accounting for 80% of the C accumulation in the leaves. In a deeply rooted ecosystem (rooting depth of 97 cm), where the root penetrated to depths close to the water-table, more than half (63%) the C accumulated in the leaves was transferred by the root uptake. We found that CO root uptake in this ecosystem depended on the distribution of methane oxidation in the soil; all C accumulated in the leaves was transferred by the root uptake when methane oxidation occurred at considerable depths (e-folding depths of 20 cm, or 80 cm). These results indicate that CO root uptake contributes significantly to CO transfer to plants if CH oxidation occurs at great depths and roots penetrate deeply into the soil.
Takahashi, Tomoyuki; *; *
Kurosu Oba Kenkyu Shimpojiumu, Osen Busshitsu No Kankyo Kyodo Yosoku Ni Kansuru Kyokuchi Kibo Shosai Moderu Narabini Sono Iko Parameta, 0, p.134 - 142, 1995/00
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