Processes, dynamics and modelling of radiocaesium cycling in a chronosequence of Chernobyl-contaminated Scots pine (Pinus sylvestris L.) plantations

Title: Processes, dynamics and modelling of radiocaesium cycling in a chronosequence of Chernobyl-contaminated Scots pine (Pinus sylvestris L.) plantations

Author: François Goor, Yves Thiry

Reference: Science of The Total Environment, Volume 325, Issues 1–3, 5 June 2004, Pages 163-180

DOI: http://dx.doi.org/10.1016/j.scitotenv.2003.10.037

Keywords: Forest biological cycling; Annual fluxes; Chronosequence; Chernobyl consequences; Wood contamination; Modelling of radiocaesium transfer

Abstract: In a large forested area affected by the Chernobyl radioactive fallout, especially in CIS, the lasting recycling of radiocaesium (¹³⁷Cs) by the trees is a source of long-term contamination of woody products. The quantitative description of the ¹³⁷Cs dynamics in contaminated forest is a prerequisite to predictive modelling and further management of such territories. Three even-aged mono-specific Scots pine stands (17, 37 and 57 years old) were selected in a contaminated woodland in southeastern Belarus to constitute an adequate chronosequence. We determined the potassium and radiocaesium annual fluxes involved in the biological cycling in each stand using a well-documented calculation methodology. Qualitatively, ¹³⁷Cs was shown to be rapidly recycled in trees through the same pathways as K and to redistribute similarly between the tree components. Compared to K, a higher fraction of ¹³⁷Cs, corresponding to about the half of the annual uptake, is immobilised in perennial organs. With tree development, trunk wood and bark become prevailing sinks for ¹³⁷Cs since they represent an increasing pool of biomass. In the pine chronosequence, the current root absorption, respectively, mobilizes 0.53, 0.32 and 0.31% year⁻¹ of the total ¹³⁷Cs pool in soil. Variations in the ¹³⁷Cs uptake do not reflect differences in the ¹³⁷Cs balance between stands. In the two older stands, 51 and 71% of the current tree contamination are related to earlier accumulation subsequent to the initial fallout interception and recycling. The soil is the dominant source of long-term tree contamination. A simple modelling based on the measured ¹³⁷Cs fluxes indicates that, for young stands, radioactive decay-corrected contamination would stabilize after reaching a maximum of 25 years after the ¹³⁷Cs deposition. Stemwood presents a maximum of 15 years after the deposition and decrease afterwards mainly through radioactive decay. In the older stands, the decontamination is constant without local maximum of ¹³⁷Cs level in the wood. The ¹³⁷Cs contamination of tree components is the result of different influential processes like root uptake, internal translocation and immobilisation. For more accurate predictions, the calibration of existing models would be benefited by comparing with the ¹³⁷Cs annual fluxes instead of the simple transfer factor coefficients. In the perspective of other applications, there is a need of such data for other radionuclides as well as for heavy metals.

URL: http://www.sciencedirect.com/science/article/pii/S0048969703006454

Genetic consequences of irradiation in scots pine Pinus sylvestris L. population

Title:  Genetic consequences of irradiation in scots pine Pinus sylvestris L. population

Author: Oficerov M.V., Igonina E.V.

Reference: Genetics, (Russian: “ГЕНЕТИКА”) 2009 Feb; 45(2):209-14.

ISSN: 1022-7954

DOI: 10.1134/S1022795409020082

Keywords: Scots pine, contamination, genetics

Abstract: The genetic consequences of irradiation were studied in a Scots pine population from a region contaminated as a result of the Chernobyl meltdown. Mutations of isozyme loci were not detected in seeds collected from trees of the first post-meltdown generation in 2004. The frequency of cells with chromosome aberrations in the root meristem of seedlings grown from the seeds did not differ from the control level. A deviation from the expected ratio 1:1 was observed for some isozyme alleles in endosperms of seeds obtained from heterozygous trees.

URL: http://www.ncbi.nlm.nih.gov/pubmed/19334615

Detecting contamination-induced tree stress within the Chernobyl exclusion zone

Title: Detecting contamination-induced tree stress within the Chernobyl exclusion zone

Author: Corine Davids, Andrew N Tyler

Reference: Remote Sensing of Environment, Volume 85, Issue 1, 25 April 2003, Pages 30-38

DOI: http://dx.doi.org/10.1016/S0034-4257(02)00184-0

Keywords: Contamination-induced tree stress; Chernobyl Nuclear Power Plant; Three Channel Vegetation Index

Abstract: The radioactive contamination from the 1986 accident at the Chernobyl Nuclear Power Plant (CNPP) caused significant change in the abundance and distribution of tree species in the exclusion zone. Some 400 ha of Scots pine (Pinus sylvestris) were killed from high levels of contamination and these areas have since been recolonised by silver birch (Betula pendula). Much work has shown that changes in leaf pigments (chlorophyll a and b, carotenoids) and biomass as a result of water and nutrient deficiencies and other environmental influences can be detected through spectral reflectance characteristics of leaves. This paper presents the results of a reconnaissance study showing that spectral reflectance measurements can also be used to detect the effect of radionuclide contamination on the vegetation in the Chernobyl exclusion zone. Through laboratory and in situ spectroradiometry of silver birch and Scots pine, we demonstrate that the chlorophyll red edge and the Three Channel Vegetation Index (TCHVI) correlate well with specific activities of ⁹⁰Sr and ¹³⁷Cs in leaves, γ-dose rates and ¹³⁷Cs inventories in soil. The results show that remote sensing has the potential of providing a valuable monitoring technique for assessing the ecological impact of radionuclide contamination.

URL: http://www.sciencedirect.com/science/article/pii/S0034425702001840

Effects of radioactive contamination on Scots pines in the remote period after the Chernobyl accident

Title: Effects of radioactive contamination on Scots pines in the remote period after the Chernobyl accident

Author: Geras’kin, Stanislav / Oudalova, Alla / Dikareva, Nina / Spiridonov, Sergey / Hinton, Thomas / Chernonog, Elena / Garnier-Laplace, Jacqueline

Reference: Ecotoxicology, 20 (6), p.1195-1208, Aug 2011 DOI: 10.1007/s10646-011-0664-7

Keywords: Chernobyl accident, Radioactive contamination, Scots pine, Absorbed doses, Cytogenetic effects, Reproductive ability, Radio-adaptation

Abstract: A 6 year study of Scots pine populations inhabiting sites in the Bryansk region of Russia radioactively contaminated as a result of the Chernobyl accident is presented. In six study sites, ¹³⁷Cs activity concentrations and heavy metal content in soils, as well as ¹³⁷Cs, ⁹⁰Sr and heavy metal concentrations in cones were measured. Doses absorbed in reproduction organs of pine trees were calculated using a dosimetric model. The maximum annual dose absorbed at the most contaminated site was about 130 mGy. Occurrence of aberrant cells scored in the root meristem of germinated seeds collected from pine trees growing on radioactively contaminated territories for over 20 years significantly exceeded the reference levels during all 6 years of the study. The data suggest that cytogenetic effects occur in Scots pine populations due to the radioactive contamination. However, no consistent differences in reproductive ability were detected between the impacted and reference populations as measured by the frequency of abortive seeds. Even though the Scots pine populations have occupied radioactively contaminated territories for two decades, there were no clear indications of adaptation to the radiation, when measured by the number of aberrant cells in root meristems of seeds exposed to an additional acute dose of radiation.

URL: http://link.springer.com/article/10.1007%2Fs10646-011-0664-7

Genome hypermethylation in Pinus silvestris of Chernobyl—a mechanism for radiation adaptation?

Title: Genome hypermethylation in Pinus silvestris of Chernobyl—a mechanism for radiation adaptation?

Author: Kovalchuk, Olga / Burke, Paula / Arkhipov, Andrey / Kuchma, Nikolaj / James, S.Jill / Kovalchuk, Igor / Pogribny, Igor

Reference: Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 529 (1-2), p.13-20, Aug 2003

doi: 10.1016/S0027-5107(03)00103-9

Keywords:Chernobyl; Radiation; Pine; Stress response; Global genome methylation

Abstract: Adaptation is a complex process by which populations of organisms respond to long-term environmental stresses by permanent genetic change. Here we present data from the natural “open-field” radiation adaptation experiment after the Chernobyl accident and provide the first evidence of the involvement of epigenetic changes in adaptation of a eukaryote-Scots pine (Pinus silvestris), to chronic radiation exposure.

URL: http://www.sciencedirect.com/science/article/pii/S0027510703001039