Research with radiation and radioisotopes to better understand plant physiology and agricultural consequences of radioactive contamination from the Fukushima Daiichi nuclear accident

Abstract

Research carried out by me and my group over the last almost four decades are summarized here. The main emphasis of my work was and continues to be on plant physiology using radiation and radioisotopes. Plants live on water and inorganic elements. In the case of water, we developed neutron imaging methods and produced 15 O-labeled water (half-life 2 min) and applied them to understand water circulation pattern in the plant. In the case of elements, we developed neutron activation analysis methods to analyze a large number of plant tissues to follow element specific distribution. Then, we developed realtime imaging system using conventional radioisotopes for the macroscopic and microscopic observation of element movement. After the accident in Fukushima Daiichi nuclear power plant, we, the academic staff of Graduate School, have been studying agricultural effects of radioactive fallout; the main results are summarized in two books published by Springer.

Real-Time Element Movement in a Plant

“…Fig. 4.16 32 P-phosphate distribution in a soybean plant [7]. 32 P-phosphate was supplied from the root, and the accumulation pattern of 32 P was recorded by RRIS.…”

“…Fig. 4.18 Image analysis of the 32 P-phosphate accumulation in the pod [7]. The pseudocolor was assigned based on the counts in the pixels.…”

“…This depletion zone was observed as a dark colored Fig. 4.29 Development of the real-time RI imaging system [7]. The sample for imaging and a scintillator device were kept in the dark in the first generation, since the CCD camera employed to image the light from the scintillator is highly sensitive to light.…”

Potentiality of Graphene Oxide and Polyoxometalate as Radionuclides Adsorbent to Restore the Environment after Fukushima Disaster: A Mini Review

“…It has been reported that the soil present around FDNPP and the soil in the neighboring prefectures were contaminated with approximately 100,000 MBq/km 2 and 10,000 MBq/km 2 of 137 Cs, respectively [1]. The soil surface area was the most contaminated [2]. It has been predicted that several radionuclides, such as cesium ( 137 Cs, 136 Cs, 134 Cs), strontium ( 90 Sr, 89 Sr), uranium (UO 2+ ), iodine ( 131 I), thorium ( 90 Th), barium ( 140 Ba), lanthanum ( 140 La), and tritium ( 3 H) are present.…”

Model-Based Design of Long-Distance Tracer Transport Experiments in Plants

“…Studying long-distance transport in plants is of high interest for the investigation of functional traits under the influence of diverse environmental factors (Van Bel, 2003 ; Jahnke et al, 2009 ). Non-invasive methods using short-lived radioisotopes have been established to detect the transport of radioactive tracer in vivo (Jahnke et al, 1998 , 2009 ; Minchin and Thorpe, 2003 ; Alexoff et al, 2011 ; Garbout et al, 2012 ; Weisenberger et al, 2013 ; Hubeau and Steppe, 2015 ; Nakanishi, 2017 ). For example, after labeling a plant with 11 CO 2 , transported 11 C can be detected and localized within the supplied plant organs from outside with positron emission tomography (PET) or scintillation detectors.…”