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Earthquake and plant root researches
Since the massive earthquake in 2011, we, the Japanese members of the editorial board, have received many encouraging messages from all over the world. First, on behalf of them, I would like to express my gratitude for these messages and the support we received from the world for our research society, where this journal is based. As for the earthquake, though it seems to have no bearing on plant root research, at least directly, linkages do exist. Here, I take a look at the earthquake from the viewpoint of plant root researches, and try to organize my thoughts and the information available from the media such as newspapers, news programs on TV, radio, and the Internet. Since the media did not always mention the sources from where it sourced the information from, I also try to clarify the sources of information in this article. I hope that this will help plant root researchers interested in the possible effects of earthquakes, tsunamis, and nuclear plant accidents. The Great East Japan Earthquake had a magnitude of 9.0; it triggered a huge tsunami, with a maximum wave run-up height of up to 40 m (Mori et al., 2011), that damaged 23,600 hectares of farmland, according to the Japanese Ministry of Agriculture, Forestry and Fisheries (MAFF)[*1]. Damage to farmland due to soil salinization and tsunami depositing were also reported (Fujikawa et al., 2011; Goto et al., 2011; Sugawara et al., 2011) MAFF aims to desalt these lands in three years[*2]. The tsunami, in turn, triggered a devastating disaster at the Fukushima Daiichi Nuclear Power Plant, the largest nuclear disaster since the Chernobyl disaster of 1986. The Nuclear and Industrial Safety Agency (NISA) of Japan estimates that the release of radioactive material to the atmosphere is approximately 10% of the Chernobyl accident, which is the only other accident to have an International Nuclear and Radiological Event Scale Level 7 rating[*3, *4]. As a result, the Director-General of the Nuclear Emergency Response Headquarters (the Japanese Prime Minister) instructed the government of Fukushima prefecture on April 22 to restrict rice cultivation in the evacuation area, planned evacuation area, and emergency evacuation preparation area[*4]. MAFF estimated that 8,300 ha of farmlands have been contaminated with radiocaesium dose of over 500 Bq/kg[*5]. The distribution maps of the radiation dose are available on the website of the Ministry of Education, Culture, Sports, Science & Technology (MEXT) of Japan[*6]. Strategies for cleaning up the area contaminated by radionuclides have been designed by the Clean-up Committee of the Atomic Energy Society of Japan, although finding a final disposal site is proving very difficult[*7]. The issue of the agricultural products produced in the region being contaminated with radionuclides is closely related to lower-dose radiation risks from the uptake of these radionuclides into human bodies. A risk assessment report on radioactive nuclides in foods was finalized by the Food Safety Commission of Japan[*8], which forms the basis on which the Japanese government makes decisions pertaining to food safety. However, as for the scientific evaluation of lower-dose radiation risks, there seem to exist many arguments due to data limitations. I would not go into detail here because of my limited expertise in this area of research. On the other hand, when it comes to radionuclides uptake by crop plants, the issue is within our research area. Mechanisms of radionuclide uptake by crop plants are important not only for avoiding internal radiation exposure to our bodies from these crops but also for the remediation of the soil contaminated by radionuclides. There exist works dealing with the mechanisms of uptake by plants, particularly for important radionuclides such as caesium (White and Broadley, 2000; Zhu and Smolders, 2000), and the soil-to-plant transfer factor (TF) of radionuclides, a parameter that measures the rate of uptake. Related to this parameter, we can find following studies as examples: soil systems and TFs of radionuclides (IAEA, 2006)[*9]; TFs of various crop plants in Japan (Uchida et al., 2007a, b; Uchida et al., 2006); TFs for specific crop plants, such as rice (Choi et al., 2005; Tsukada et al., 2002; Tsukada et al., 2005), potato (Tsukada and Nakamura, 1999), Chinese cabbage, and radish (Choi et al., 1998); and TF of spruce (Brunner et al., 1996). Here, we can see the contribution of Plant Root researchers, and I would specifically like to mention Dr. White and Dr. Brunner, who are active members of our editorial board. Further, farmers examine the radioactivity of their crop products with the help of local governments and agricultural research centers, and even try to determine the TFs. Some of our editorial board members are actually involved in a project for the assessment of radiocaesium soil conta-mination of rice fields in Fukushima. The recovery from contamination has only just begun. Further, I have to mention that the world faced an-other record-breaking natural disaster in 2011 – a severe drought that hit the Horn of Africa. This was reported to be the worst drought in 60 years and the lives and livelihoods of over 12 million people have been threatened by a severe food crisis, according to the FAO Executive Brief Issue dated Aug 4, 2011[*10]. Plant root researches are obviously related to this issue and hopefully can contribute in the long run, though not in an immediate way. Regarding the Journal, we have entered a new term: 2012–2013. I have again been appointed to the position of Editor-in-Chief of the Plant Root for the new term by the Japanese Society for Root Research, and we have new subject editors in the Editorial Board. I want to express my gratitude to all authors for their contributions, to the researchers who have submitted manuscripts to this journal, and to our managing editors, subject editors, and reviewers.
Brunner I, Frey B, Riesen TK 1996 Influence of ectomycorrhization and cesium/potassium ratio on uptake and localization of cesium in Norway spruce seedlings. Tree Physiol. 16: 705-711.
Choi YH, Lee CW, Kim SR, Lee JH, Jo JS 1998 Effect of application time of radionuclides on their root uptake by Chinese cabbage and radish. J. Env. Radioactiv. 39: 183-198.
Choi YH, Lim KM, Park HG, Park DW, Kang HS, Lee HS 2005 Transfer of 137Cs to rice plants from various paddy soils contaminated under flooded conditions at different growth stages. J. Env. Radioactiv. 80: 45-58.
Fujikawa T, Okazawa H, Nakamura T, Takeuchi Y, Komamura M 2011 Physical and chemical properties of tsunami deposits in the Northeast area of Fukushima prefecture after the Tohoku-Kanto Earthquake. Int. J. Geomate 1: 2186-2990.
Goto K, Chague-Goff C, Fujino S, Goff J, Jaffe B, Nishimura Y, Richmond B, Sugawara D, Szczucinski W, Tappin DR, Witter RC, Yulianto E 2011 New insights of tsunami hazard from the 2011 Tohoku-oki event. Mar. Geol. 290: 46-50.
IAEA (ed) 2006 Classification of soil systems on the basis of transfer factors of radionuclides from soil to reference plants. International Atomic Energy Agency, Vienna, Austria.
Mori N, Takahashi T, Yasuda T, Yanagisawa H 2011 Survey of 2011 Tohoku earthquake tsunami inundation and run-up. Geophys. Res. Lett. 38: L00G14.
Sugawara D, Goto K, Chagugue-Goff C, Fujino S, Goff J, Jaffe B, Nishimura Y, Richmond B, Szczucinski W, Tappin DR 2011 Initial field survey report of the 2011 East Japan Tsunami in Sendai, Natori and Iwanuma Cities. UNESCO-IOC.
Tsukada H, Hasegawa H, Hisamatsu S, Yamasaki S 2002 Rice uptake and distributions of radioactive 137Cs, stable 133Cs and K from soil. Environ. Pollut. 117: 403-409.
Tsukada H, Nakamura Y 1999 Transfer of 137Cs and stable Cs from soil to potato in agricultural fields. Sci. Total Environ. 228: 111-120.
Tsukada H, Takeda A, Takahashi T, Hasegawa H, Hisamatsu S, Inaba J 2005 Uptake and distribution of 90Sr and stable Sr in rice plants. J. Env. Radioactiv. 81: 221-231.
Uchida S, Tagami K, Hirai I 2007a Soil-to-plant transfer factors of stable elements and naturally occurring radionuclides: (1) Upland field crops collected in Japan. J. Nucl. Sci. Technol. 44: 628-640.
Uchida S, Tagami K, Hirai I 2007b Soil-to-plant transfer factors of stable elements and naturally occurring radionuclides: (2) Rice collected in Japan. J. Nucl. Sci. Technol. 44: 779-790.
Uchida S, Tagami K, Komamura M 2006 Variation of transfer factors of radionuclides for food crops in Japan. Classification of soil systems on the basis of transfer factors of radionuclides from soil to reference plants. Food and Environmental Protection Section International Atomic Energy Agency, Vienna, Austria, pp 101-112.
White PJ, Broadley MR 2000 Tansley review No. 113. New Phytol. 147: 241-256.
Zhu YG, Smolders E 2000 Plant uptake of radiocesium: a review of mechanisms, regulation and application. J. Exp. Bot. 51: 1635-1645.
Editor-in-chief, Plant Root
I. Karahara operating a High Voltage EM, Hitachi H-1250M, at National Institute for Physiological Sciences