Online ISSN: 1884-4111 Print ISSN: 0033-8303
Radioisotopes 66(9): 321-329 (2017)


イネ科草本植物の群落構造が群落内の風速に与える影響—TRU廃棄物処理における安全評価にむけてImpacts of Height and Density of Gramineous Plant Community on Internal Wind Speed —Toward Safety Assessments of TRU Waste Disposal—

1兵庫県立大学環境人間学部School of Human Science and Environment, the University of Hyogo ◇ 670–0092 兵庫県姫路市新在家本町1–1–12 ◇ 1–1–12 Shinzaike-Honcho, Himeji-shi, Hyogo Pref. 670–0092, Japan

2量子科学技術研究開発機構National Institute for Quantum and Radiological Science and Technology, National Institute of Radiological Sciences ◇ 263–8555 千葉県千葉市稲毛区穴川4–9–1 ◇ 4–9–1 Anagawa, Inage-ku, Chiba-shi, Chiba Pref. 263–8555, Japan

3琉球大学農学部Faculty of Agriculture, University of the Ryukyus ◇ 沖縄県中頭郡西原町千原1 ◇ 1 Senbaru, Nishiharacho, Nakagamigun, Okinawa Pref. 903–0213, Japan

受付日:2017年2月3日Received: February 3, 2017
受理日:2017年4月28日Accepted: April 28, 2017
発行日:2017年9月15日Published: September 15, 2017


Radioactive carbon (14C) is the dominant radioactive nuclide in transuranic (TRU) waste. However, only a few studies to date have taken into account 14C transition in its gaseous form (14CO2). For an appropriate biosphere assessment of geological disposal, it is important to understand the degree of 14CO2 mixing with ambient air by vegetation. To evaluate the impacts of the structure of the plant community, relative to the vertical and horizontal wind speed, we characterized the structure of two gramineous plant communities (community-1, community-2) and compared the wind at three heights (middle, top, and above) of each community. The comparison of the two plant communities revealed that the biomass was the same, but the plant height of community-1 was 78% of that of community-2, and its vegetation density was approximately twice as high. Wind speeds of middle of the community with a higher vegetation density were less affected by the winds outside the community. It was assumed that the winds in the plant communities became more restricted as the community density increased. It is therefore suggested that effects of vegetation density are an important factor for the retention and the transition of 14CO2 to vegetation.

Key words: Geological disposal; 14CO2; horizontal wind; vertical wind; vegetation density

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