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Tanaka T.,University of Shizuoka | Murakami K.,Fukushima Prefectural Forestry Research Center | Kumata A.,Fukushima Prefectural Ken nan Agriculture and Forestry Office | Kawai Y.,Akita Prefectural University
Wood Science and Technology | Year: 2015

A method to be potentially used for radiocesium decontamination from timber harvested in Fukushima region, where fallout from the Fukushima Daiichi nuclear disaster was deposited, involves drying the timber and planing away the contaminated wood. The objective of this study was to investigate the influence of drying temperature on the migration of cesium dissolved in the liquid water of sugi (Cryptomeria japonica D. Don) sapwood during the drying process. Small specimens of sugi sapwood impregnated with aqueous cesium chloride (CsCl) solution were dried at 20 or 90 °C, and the migration of CsCl during drying was examined by means of X-ray imaging. The results of this study indicate that the drying of sugi sapwood at any temperature causes surface accumulation of dissolved cesium, which is affected by both the drying temperature and grain orientation of the surface. Statistical analysis confirmed that a high drying temperature causes greater surface accumulation of CsCl during drying. It is recommended to use higher temperatures to dry sugi sapwood when employing the drying/planing method for radiocesium decontamination from timber. © 2015, Springer-Verlag Berlin Heidelberg.


Ozawa H.,Fukushima Prefectural Forestry Research Center | Watanabe A.,Japan Forestry and Forest Products Research Institute | Uchiyama K.,Japan Forestry and Forest Products Research Institute | Saito Y.,University of Tokyo | Ide Y.,University of Tokyo
Journal of Forest Research | Year: 2012

We attempted to evaluate the genetic diversity of long-distance transported pollen flowing over fragmented Pinus densiflora populations during a mating season. A P. densiflora clonal seed orchard, which was located in a rural area where many fragmented populations exist, was selected for pollen capture. Immigrant pollen captured by three clones having different flowering times was regarded as the pollen flowing over fragmented populations during a mating season. The genetic diversity (He) values of the immigrant pollen captured by the three clones were high (He > 0.894). The correlation of paternity (rp) values of the seeds having immigrant parent generated from the three clones were calculated to be negative. From these parameters, the pollen cloud is considered to have maintained high genetic diversity during the mating season. The genetic composition of the pollen cloud showed slight variation. The pollen captured by different trees (i. e., clonal ramets of the three clones) was significantly different based on analysis of molecular variance. Especially, the pollen pools captured by trees planted in the western side of the orchard were significantly different from the gene pool of the surrounding populations. Factors affecting this differentiation could be that the donors of the pollen transported to the orchard vary with time, as well as nonuniform dispersal of the pollen. From these results, the pollen flowing over fragmented P. densiflora populations is considered to have high genetic diversity, compensating to some extent for fragmentation. © 2011 The Japanese Forest Society and Springer.


Ozawa H.,Fukushima Prefectural Forestry Research Center | Watanabe A.,Kyushu University | Uchiyama K.,Japan Forestry and Forest Products Research Institute | Saito Y.,University of Tokyo | Ide Y.,University of Tokyo
Journal of Heredity | Year: 2013

Long-distance dispersal (LDD) of seeds has a critical impact on species survival in patchy landscapes. However, relative to pollen dispersal, empirical data on how seed LDD affects genetic diversity in fragmented populations have been poorly reported. Thus, we attempted to indirectly evaluate the influence of seed LDD by estimating maternal and paternal inbreeding in the seed rain of fragmented 8 Pinus densiflora populations. In total, the sample size was 458 seeds and 306 adult trees. Inbreeding was estimated by common parentage analysis to evaluate gene flow within populations and by sibship reconstruction analysis to estimate gene flow within and among populations. In the parentage analysis, the observed probability that sampled seeds had the same parents within populations was significantly larger than the expected probability in many populations. This result suggested that gene dispersal was limited to within populations. In the sibship reconstruction, many donors both within and among populations appeared to contribute to sampled seeds. Significant differences in sibling ratios were not detected between paternity and maternity. These results suggested that seed-mediated gene flow and pollen-mediated gene flow from outside population contributed some extent to high genetic diversity of the seed rain (HE > 0.854). We emphasize that pine seeds may have excellent potential for gene exchange within and among populations. © The American Genetic Association. 2013. All rights reserved.


PubMed | Tokyo Metroplitan University and Fukushima Prefectural Forestry Research Center
Type: | Journal: Journal of environmental radioactivity | Year: 2016

The changes in the distribution of (137)Cs in the wood of Japanese cedar (Cryptomeria japonica) trunks within three years after the Fukushima Dai-ichi Nuclear Power Plant (FDNP) accident in 2011 were investigated. Thirteen trees were felled to collect samples at 6 forests in 2 regions of the Fukushima prefecture. The radial distribution of (137)Cs in the wood was measured at different heights. Profiles of (137)Cs distribution in the wood changed considerably from 2011 to 2013, and the process of (137)Cs distribution change in the wood was clarified. From 2011 to 2012, the active transportation from sapwood to heartwood and the radial diffusion in heartwood proceeded quickly, and the radial (137)Cs distribution differed according to the vertical positon of trees. From 2012 to 2013, the vertical diffusion of (137)Cs from the treetop to the ground, probably caused by the gradient of (137)Cs concentration in the trunk, was observed. Eventually, the radial (137)Cs distributions were nearly identical at any vertical positions in 2013. Our results suggested that the active transportation from sapwood to heartwood and the vertical and radial diffusion in heartwood proceeded according to the vertical position of the tree and (137)Cs distribution in the wood approached the equilibrium state within three years after the accident.


Sugiura Y.,Nagoya University | Kanasashi T.,Nagoya University | Ogata Y.,Nagoya University | Ozawa H.,Fukushima Prefectural Forestry Research Center | Takenaka C.,Nagoya University
Journal of Environmental Radioactivity | Year: 2016

Through the assessments of radioactive contamination after the Fukushima Dai-ichi Nuclear Power Plant (F1NPP) accident, it has been reported that some sprouts of Chengiopanax sciadophylloides (Franch. et Sav.) at the site contained radiocesium (134,137Cs) at higher concentrations than the other plants. To assess the phytoremediation properties of C. sciadophylloides for 137Cs decontamination, we aimed to quantify the 137Cs accumulation in C. sciadophylloides. We measured the 137Cs concentrations in various organs of C. sciadophylloides collected from the forest in the town of Kawamata, Fukushima prefecture, together with the concentrations of other elements [potassium (K), rubidium, 133Cs, calcium, strontium, and manganese] present. In addition, we compared the foliar concentrations of these elements in C. sciadophylloides with those in four different deciduous tree species. The mean of foliar 137Cs concentration in C. sciadophylloides was 28.1 kBq kg-1 DW, one order of magnitude higher than that found in the other species. The 137Cs concentrations were in the order of leaves > bark > wood. The wood of the treetop, leaf scars, and roots contained higher amounts of 137Cs than that of the trunk. From the distribution of 137Cs in C. sciadophylloides, we confirmed that 137Cs tends to accumulate in the young growing parts. The difference in the distribution of 137Cs and 133Cs indicated that surface uptake of 137Cs occurs. A significant correlation between K and 137Cs concentrations in each organ was found, which suggested that 137Cs in the plant body is transferred through the same pathway as K. On the other hand, there was no correlation between foliar K and 137Cs concentrations, implying that the uptake ratio of K to 137Cs was different for each individual. To determine the factors driving specific 137Cs accumulation and/or the variability of the ratio between K and 137Cs, the distribution of 137Cs and the root in soil, the difference of the expression of transporter, and the existence of mycorrhizal fungi should be considered. However, further research is required. © 2015 Elsevier Ltd.


Sugiura Y.,Nagoya University | Shibata M.,Nagoya University | Ogata Y.,Nagoya University | Ozawa H.,Fukushima Prefectural Forestry Research Center | And 2 more authors.
Journal of Environmental Radioactivity | Year: 2016

Radiocesium (137Cs) transfer to plants immediately after the Fukushima Dai-ichi Nuclear Power Plant accident was investigated by collecting newly emerged leaf and soil samples between May 2011 and November 2012 from 20 sites in the Fukushima prefecture. Radiocesium concentrations in leaf and soil samples were measured to calculate concentration ratios (CR). Woody plants exhibited high CR values because 137Cs deposited on stems and/or leaves were transferred to newly emerging tissues. The CR values in 2012 declined as compared to that in 2011. Exchangeable 137Cs rates in soil (extraction rate) samples were measured at five sites. These rates decreased at four sites in 2012 and depended on environmental conditions and soil type. Both CR values and extraction rates decreased in 2012. However, CR values reflected the changes in extraction rates and characteristics of each species. Amaranthaceae, Chenopodiaceae, and Polygonaceae, which had been identified as Cs accumulators, presented no clear 137Cs accumulation ability. In 2012, the perennial plant Houttuynia cordata and deciduous trees Chengiopanax sciadophylloides and Acer crataegifolium displayed high CR values, indicating that these species are 137Cs accumulators and may be considered as potential species for phytoremediation. © 2016 Elsevier Ltd.


PubMed | Fukushima Prefectural Forestry Research Center and Nagoya University
Type: | Journal: Journal of environmental radioactivity | Year: 2016

Radiocesium ((137)Cs) transfer to plants immediately after the Fukushima Dai-ichi Nuclear Power Plant accident was investigated by collecting newly emerged leaf and soil samples between May 2011 and November 2012 from 20 sites in the Fukushima prefecture. Radiocesium concentrations in leaf and soil samples were measured to calculate concentration ratios (CR). Woody plants exhibited high CR values because (137)Cs deposited on stems and/or leaves were transferred to newly emerging tissues. The CR values in 2012 declined as compared to that in 2011. Exchangeable (137)Cs rates in soil (extraction rate) samples were measured at five sites. These rates decreased at four sites in 2012 and depended on environmental conditions and soil type. Both CR values and extraction rates decreased in 2012. However, CR values reflected the changes in extraction rates and characteristics of each species. Amaranthaceae, Chenopodiaceae, and Polygonaceae, which had been identified as Cs accumulators, presented no clear (137)Cs accumulation ability. In 2012, the perennial plant Houttuynia cordata and deciduous trees Chengiopanax sciadophylloides and Acer crataegifolium displayed high CR values, indicating that these species are (137)Cs accumulators and may be considered as potential species for phytoremediation.


PubMed | Fukushima Prefectural Forestry Research Center and Nagoya University
Type: | Journal: Journal of environmental radioactivity | Year: 2016

We conducted an experiment to investigate the potential of phytoremediation by soil amendments in a forest area. To desorb radiocesium (


PubMed | Fukushima Prefectural Forestry Research Center and Nagoya University
Type: | Journal: Journal of environmental radioactivity | Year: 2015

Through the assessments of radioactive contamination after the Fukushima Dai-ichi Nuclear Power Plant (F1NPP) accident, it has been reported that some sprouts of Chengiopanax sciadophylloides (Franch. et Sav.) at the site contained radiocesium (((134),)(137)Cs) at higher concentrations than the other plants. To assess the phytoremediation properties of C.sciadophylloides for (137)Cs decontamination, we aimed to quantify the (137)Cs accumulation in C.sciadophylloides. We measured the (137)Cs concentrations in various organs of C. sciadophylloides collected from the forest in the town of Kawamata, Fukushima prefecture, together with the concentrations of other elements [potassium (K), rubidium, (133)Cs, calcium, strontium, and manganese] present. In addition, we compared the foliar concentrations of these elements in C. sciadophylloides with those in four different deciduous tree species. The mean of foliar (137)Cs concentration in C. sciadophylloides was 28.1kBqkg(-1) DW, one order of magnitude higher than that found in the other species. The (137)Cs concentrations were in the order of leaves > bark > wood. The wood of the treetop, leaf scars, and roots contained higher amounts of (137)Cs than that of the trunk. From the distribution of (137)Cs in C. sciadophylloides, we confirmed that (137)Cs tends to accumulate in the young growing parts. The difference in the distribution of (137)Cs and (133)Cs indicated that surface uptake of (137)Cs occurs. A significant correlation between K and (137)Cs concentrations in each organ was found, which suggested that (137)Cs in the plant body is transferred through the same pathway as K. On the other hand, there was no correlation between foliar K and (137)Cs concentrations, implying that the uptake ratio of K to (137)Cs was different for each individual. To determine the factors driving specific (137)Cs accumulation and/or the variability of the ratio between K and (137)Cs, the distribution of (137)Cs and the root in soil, the difference of the expression of transporter, and the existence of mycorrhizal fungi should be considered. However, further research is required.


PubMed | Fukushima Prefectural Forestry Research Center
Type: Journal Article | Journal: The Journal of heredity | Year: 2013

Long-distance dispersal (LDD) of seeds has a critical impact on species survival in patchy landscapes. However, relative to pollen dispersal, empirical data on how seed LDD affects genetic diversity in fragmented populations have been poorly reported. Thus, we attempted to indirectly evaluate the influence of seed LDD by estimating maternal and paternal inbreeding in the seed rain of fragmented 8 Pinus densiflora populations. In total, the sample size was 458 seeds and 306 adult trees. Inbreeding was estimated by common parentage analysis to evaluate gene flow within populations and by sibship reconstruction analysis to estimate gene flow within and among populations. In the parentage analysis, the observed probability that sampled seeds had the same parents within populations was significantly larger than the expected probability in many populations. This result suggested that gene dispersal was limited to within populations. In the sibship reconstruction, many donors both within and among populations appeared to contribute to sampled seeds. Significant differences in sibling ratios were not detected between paternity and maternity. These results suggested that seed-mediated gene flow and pollen-mediated gene flow from outside population contributed some extent to high genetic diversity of the seed rain (H E > 0.854). We emphasize that pine seeds may have excellent potential for gene exchange within and among populations.

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