ECOTOXIC EFFECTS IN PINUS SYLVESTRIS L POPULATIONS GROWING IN THE VICINITY OF A RADIOACTIVE WASTE STORAGE FACILITY AND IN THE 30-KM ZONE OF THE CHERNOBYL NPP

D.V. Vasiliev, V.G. Dikarev, N.S. Dikareva, S.A. Geraskin, A.A. Oudalova

Russian Institute of Agricultural Radiology and Agroecology, RAAS, Obninsk, Russia

The influence was studied of the regional enterprise for processing and temporary storage of radioactive wastes, “Radon” LWPE (Leningrad region), on plant components of natural ecosystems.

Materials and Methods

Cones and young shoots were collected (in autumn, 1997–2002 and in May, 1998–2002, respectively) from trees of three Scotch pine populations located at the LWPE territory, in the centre of the Sosnovy Bor town, and at 30-km distance from the town in an ecologically safe site chosen considering the wind rose. A similar experiment was carried out earlier in the 30-km Chernobyl NPP zone, where populations of Scots pine within the asphalt-concrete plant (ACP, "Red wood") site and the Cherevach village (rather safe site within the 30-km ChNPP zone) were examined. The population within an ecologically safe area of the Kaluga region was used as a reference. The collected cones were allowed to ripen up to opening. Seeds were germinated in thermostat at 240 C in Petri dishes on a filter paper. The seedling roots at the cell stage of first mitosis (10-15 (в опубликованных статьях указано 8-14 мм – несоответствия не должно быть!) mm in length) were fixed in ethanol-acetic acid (3:1). Squashed temporary preparations of seedling root apical meristem and intercalar meristem of young needles were stained with acetic orcein. All anaphase and telophase cells were analyzed in each preparation and aberrations were scored; the aberration spectrum analysis was carried out with separation of chromatid (single) and chromosome (double) bridges and fragments, multipolar mitoses, and also chromosome laggings (genome mutations).

Results and Discussion

Сytogenetic analysis revealed an increased damage level in meristematic cells of reproductive (seeds) (Figure 1) and vegetative (needles) organs of Scotch pine (Pinus sylvestris L.) sampled in the Sosnovy Bor town and at the LWPE territory [1, 2]. The frequencies of cytogenetic disturbances at the 'Radon' LWPE site were, however, well below those in the Scots pine populations from the sub-lethal zone (the ACP site) of the 30-km Chernobyl NPP zone (Figure 1). It should be noted that, while the incidence of cytogenetic damage in the samples from the 30-km Chernobyl NPP zone increased with radiation exposure, the cytogenetic damage found in the seed and needle samples from the 'Radon' LWPE site could not be attributed to the radiation exposure alone.

Additional information on the possible factors affecting the trees may be obtained from an analysis of the mutation spectrum. Mitotic anomalies occurrences in the Scots pine populations of Sosnovy Bor and ‘Radon’ LWPE sites exceeded corresponding reference levels [2]. At these two sites, cytogenetic damages of rare type, so-called three-polar mitosis, were revealed, while there were no multipolar mitoses as in the reference population (Figure 2) as in the earlier Chernobyl-related study [1]. It allows a conclusion about the presence of significant components of chemical pollution in the Sosnovy Bor town (почему?).

The regression analysis indicates that the frequencies of cytogenetic disturbances increase with time in all the tree populations of the Leningrad Region.

The seeds sampled in the Leningrad Region were treated with acute g-irradiation at a dose of 15 Gy. The seeds from the populations of the LWPE site and Sosnovy Bor town were found to be more radioresistant in comparison to the reference ones (Figure 3). It gives evidence on the presence of a selection directed on increasing in an efficiency of the repair system. Such increased repair efficiency reflects an appearance of processes of genetic structure changes caused by long-term anthropogenic influence.

Conclusions

As a whole, our findings demonstrate that an analysis of the frequency and spectrum of cytogenetic disturbances in both reproductive (seeds) and vegetative (needles) structures of Scots pine may be used to quantify the differences in pollution-induced stress not only in areas with prominent damage to the conifers, but also in forests with slight or no visible symptoms of a pollution impact.

References

1.  GERAS’KIN S.A., ZIMINA L.M., DIKAREV V.G. et al., 2003 Bioindication of the anthropogenic effects on micropopulations of Pinus sylvestris, L. in the vicinity of a plant for the storage and processing of radioactive waste and in the Chernobyl NPP zone, J. Env. Radioactivity 66 171-180.

2.  GERAS’KIN S.A., KIM J.K., OUDALOVA A.A, VASILIYEV D.V., et al., 2005, Biomonitoring the genotoxicity of the environmental factors with wild populations of Scots pine in the vicinity of a plant for the storage of radioactive waste , Mutation Research, in press.