Influence of the FNPP Accident on Coniferous Trees: A Review

Abstract

After the accident at Fukushima Daiichi Nuclear Power Plant (FNPP) in March 2011, high contamination levels in the environment suggest possible effects of radiation on nonhuman biota. In order to understand the effect on wild animals and plants, field investigations were conducted in the ex-evacuation zone where ambient dose-rate was particularly high. For the purpose of biomonitoring of the radiation effect, coniferous trees have been demonstrated to be suitable indicator organisms because of their high radiosensitivity, which was revealed decades ago by experiments using gamma irradiation facilities. Subsequently, radiosensitive damages in conifers became real after the Chernobyl nuclear power plant (CNPP) accident in 1986, where local coniferous species showed distinct biological damage in the radioactively contaminated areas. This review outlines the results obtained from the past radiation experiments and cases in surrounding forests after the CNPP accident for radiation effect studies of coniferous trees. By referring to them, the author explains the present situation and problems of the investigation on coniferous trees after the FNPP accident.

Effects of Ionizing Radiation on Flora Ten Years after the Fukushima Dai-ichi Disaster

“…Several studies have analyzed these higher plants in the forests of the ex-evacuation zone. Precisely in this area, about eight months after the accident, in November 2011, a thorough investigation was conducted, but no chronic radiation injuries such as morphological anomalies or yellowing and fall of the leaves were observed [30][31][32][33]. These same observations also occurred in the forest most contaminated by the accident, about 3 km west of FNPP [28][29][30].…”

“…At the time of the accident, in the areas around FNPP, there were several warm temperate forests that have suffered radionuclides deposition (Figure 2). The forests of this area were and are mainly formed by coniferous plants such as Japanese red pine (Pinus densiflora), Japanese fir (Abies firma), Japanese cypress (Chamaecyparis obtusa), Japanese cedar (Cryptomeria japonica) and broad-leaved trees such as Konara oak (Quercus serrata) [8,[28][29][30]. Several studies have analyzed these higher plants in the forests of the ex-evacuation zone.…”

“…Precisely in this area, about eight months after the accident, in November 2011, a thorough investigation was conducted, but no chronic radiation injuries such as morphological anomalies or yellowing and fall of the leaves were observed [30][31][32][33]. These same observations also occurred in the forest most contaminated by the accident, about 3 km west of FNPP [28][29][30]. Contrariwise to the Chernobyl Nuclear Power Plant (CNPP) accident where radiation injury was observed relatively early, in the case of the FNPP accident, large-scale radiation damage did not occur in plants following sub-acute exposure [12,[34][35][36].…”

“…Contrariwise to the Chernobyl Nuclear Power Plant (CNPP) accident where radiation injury was observed relatively early, in the case of the FNPP accident, large-scale radiation damage did not occur in plants following sub-acute exposure [12,[34][35][36]. However, to evaluate the effects of ionizing radiation on conifers in the ex-evacuation zone over the medium and long term, further studies have been performed [28,30]. In January 2015, assessments were conducted in the area around FNPP.…”

“…In January 2015, assessments were conducted in the area around FNPP. Specifically, morphology was observed in the Japanese fir population present in the forest [29,30]. In detail, the observation was performed as follows: within the ex-evacuation zone, three distinct zones were examined, each with an area of approximately 1 km 2 .…”