Features of Prooxidant and Antioxidant Systems of Greater Plantain <Emphasis Type="Italic">Plantago major</Emphasis> Growing for a Long Time under Conditions of Radioactive Contamination

The viability and state of the prooxidant and antioxidant systems of Plantago major seed progeny from cenopopulations growing for a long time at the East-Ural Radioactive Trace (EURT) has been estimated. Radiation doses of maternal plants have been calculated using our empirical data in ERICA Tool. The absorbed dose rates for plantain in the EURT zone varied from 19 to 157 μGy/h, which is 178–1455 times higher than the background values. These relatively low levels of chronic irradiation did not cause a significant decrease in the survival rate of P. major seed progeny; the rate of root and leaf growth decreased only in seedlings from the most polluted cenopopulation. A prooxidant shift was revealed in seedlings from the EURT zone. Given the same regime of enzyme protection (SOD, CAT, and POX) against active oxygen forms, the average rate of accumulation of secondary products of lipid peroxidation (MDA) was 3.3 times higher in impact samples than in background samples. The level of prooxidant shift in impact samples is not linearly related to dose rates that are classified as low doses.     

Microscale Spatial Variation in Forest Litter Phytotoxicity

The spatial variation (within a 100 × 100 m plot) in the pollution of forest litter with heavy metals (Cu, Cd, Pb, and Zn), its acidity, and phytotoxicity (measured by the results of the root test using seedlings from a genetically homogeneous sample of common dandelion (Taraxacum officinale s.l.) have been estimated. Forest litter has been sampled in three zones differing in the toxic impact of long-term polymetal pollution by emissions from a copper-smelting plant emissions in the Middle Urals. The phytotoxicity variation is maximum in a moderately polluted plot, where both very high and very low pollution levels were observed, which determines a substantially nonlinear dose–effect relationship. The litter phytotoxicity is mainly accounted for by exchangeable forms of metals. Biological testing of samples from the most polluted plot has demonstrated marked antagonism between heavy metals and acidity.     

Variation in the seed progeny of smooth brome grass,Bromus inermis Leyss., under conditions of chronic irradiation in the zone of the Eastern Ural Radioactive Trace

Long-term studies have been performed on the seed progeny of B. inermis from test plots established along the radioactive contamination gradient in the zone of the Eastern Ural Radioactive Trace (EURT), where dose loads on maternal plants and embryos of seeds from chronically irradiated cenopopulations (with natural background radiation taken into account) exceed control values by factors of 2 to 107. Interannual and individual variation in the viability, mutability, and radiosensitivity of the seed progeny has been revealed. Against the background of high interpopulation variation in test parameters in the EURT zone, weather conditions appear to have no significant effect on seed quality, while such effects are appreciable in background cenopopulations. It has been shown that a positive correlation exist between the initial viability of the seed progeny and their radioresistance. Chronic irradiation in a wide dose range induces an increased frequency of different mutations and morphological modifications. The contents of low-molecular antioxidants in seedlings from impact cenopopulations proved to be higher than in the background sample. The results obtained characterize the potential of protective and restorative mechanisms acquired in the course of evolution that allow plants to survive in the changing environment under exposure to technogenic stress.     

Assessment of radiation impact on <Emphasis Type="Italic">Stellaria graminea</Emphasis> cenopopulations in the zone of the Eastern Ural Radioactive Trace

The seed progeny of the little starwort (Stellaria graminea) growing in the zone of the Eastern Ural Radioactive Trace (EURT) and in background areas was studied. The radiation exposure of this species in the EURT zone was three orders of magnitude higher than in the background. Evidence was obtained for high interannual variation in seed viability and tolerance to additional acute irradiation, but no specific connection was revealed between these parameters and radioactive contamination level in plant habitats. Weather conditions are an important source of variation in seed viability, but significant influence of temperature and precipitation was revealed only for cenopopulations of the EURT. The proportion of seedlings with morphoses in samples from the EURT was found to be increased; additional irradiation facilitated the detection of latent abnormalities. A negative correlation between seedling survival rate and the content of low-molecular antioxidants in the seedlings was revealed in all test areas. The allozyme structure of starwort cenopopulation was analyzed for the first time. A directed switch of allele frequencies at loci Pgi-2 and Fdh was revealed in samples from the EURT.     

Adaptation of greater plantain, <Emphasis Type="Italic">Plantago major</Emphasis> L., to long-term radiation and chemical exposure

A comparative study of the greater plantain seed progeny was performed with samples from cenopopulations growing for a long time under conditions of radioactive contamination (in the Eastern Ural Radioactive Trace, EURT) or chemical pollution (in the impact zone of the Nizhny Tagil Iron and Steel Works, NTMK). The progeny of plants from the NTMK zone had low viability but proved to be resistant to the additional impact of a “new” factor (acute γ-irradiation) as well as of the “habitual” factor (heavy metal toxicity). Plantain seeds from the EURT area showed high viability and low heavy metal and radiation resistance; i.e., no preadaptation effect was revealed. In experiments on growing plants from different cenopopulations in plot culture, samples from the EURT zone were characterized mainly by morphoses of generative organs, while samples from the NTMK area, by morphoses of vegetative organs.     

Pathways of adaptation of common dandelion cenopopulations to long-term chemical and radiation influences

A comparative study of the seed progeny of dandelions was performed with samples from cenopopulations growing for a long time under conditions of radioactive contamination (the zone of the Eastern Ural Radioactive Trace, EURT) or chemical pollution (the impact zone of the Nizhnii Tagil Metallurgical Plant, NTMP). The viability of seeds proved to decrease in a similar way along with an increase in technogenic pressure, irrespective of its nature. Experiments on acute exposure to heavy metals and γ-irradiation made it possible to reveal the adaptive capacities of the seed progeny from each cenopopulation. The background sample (formed beyond the zone of any impact) was relatively resistant to irradiation and very sensitive to heavy metals. The cenopopulations from the EURT and NTMP zones manifested nonspecific responses to the effects of both habitual and new factors.     

Analysis of Local Dandelion (Taraxacum officinales.l.) Cenopopulations from Radioactively Contaminated Zones

Local dandelion (Taraxacum officinales.l.) populations were studied in the areas of the Eastern Ural Radioactive Trace and the floodplain of the Techa River in its upper reaches. In impact plots, the density of soil and plant cover contamination with ⁹⁰Sr and ¹³⁷Cs exceeded the background level by factors of 13–440 and 2–500, respectively; the radiation load exceeded the background level by factors of 1.5 to 45. The seed progeny of plants from these plots was characterized by a high proportion of abnormal seedlings and an increased level of chromosome aberrations in meristem cells. In some years, variation in the seedling viability, growth rate, and developmental rate in these plots exceeded the reaction norm of plants from the background plot, demonstrating both stimulation and inhibition of growth processes. The response of seeds to acute irradiation at high challenging doses varied depending on the level of background radiation in the plots.     

The survival strategy of Crepis tectorum L. under conditions of chronic atmospheric pollution

The results of demographic studies on Crepis tectorum L. populations from polluted and clean habitats are presented. They show that these populations significantly differ from each other in a number of parameters, including the seasonal dynamics of seed germination, the number of generations, the time of plant transition to reproduction, and the rate of generation succession in general. These data provide evidence that populations of annual or biennial plants can employ different survival strategies when growing under conditions of pollution or its absence.     

Composition of pied flycatcher (<Emphasis Type="Italic">Ficedula hypoleuca</Emphasis> Pall.) nestling diet in industrially polluted area

The composition of pied flycatcher (Ficedula hypoleuca Pall.) nestling diet was studied in the zone of strong pollution with emissions from the Middle Ural Copper Smelter (Revda, Sverdlovsk oblast) and in the background area from 2005 to 2007. The results show that diversity of the diet decreases and prevalence in it of one insect taxon (Lepidoptera) increases near the source of emissions. The proportion of uncharacteristic food objects (orthopterans, herpetobiont invertebrates) and variation in the size of invertebrates brought by parents to their nestlings increase, which is explained by degradation of forest habitats in the polluted area. Pied flycatchers provide nestlings with sufficient quantities of food, but its quality in the polluted zone is lower than in the background area.     

Intraspecific variation in Melandrium album along a radioactive contamination gradient at the Eastern Ural radioactive trace

Specific ecogenetic features of plants and parameters of seed progeny have been studied in Melandrium album cenopopulations from test plots established along the radioactive contamination gradient in the zone of the Eastern Ural Radioactive Trace (EURT), where absorbed radiation doses in buffer and impact plots exceeded the background level by factors of 2–18 and 330–418, respectively. It has been shown that interannual variation in parameters characterizing the viability of seed progeny largely depends on fluctuations of weather conditions. This dependence is more distinct in cenopopulations from the EURT than in control samples, which is indicative of interaction between radiation and other relevant ecological factors. The radioresistance of seed progeny is contingent on its viability, being independent of radiation load at the sites of maternal plant growth. Hermaphrodite plants occur only in irradiated M. album cenopopulations. This character is inherited: all F ₁ descendants of such plants grown in a vegetation experiment had hermaphrodite flowers. The mutability of seed progeny formed in the EURT zone exceeds the background level. The occurrence and frequencies of recorded anomalies has proved to vary by years and, therefore, can be interpreted as nonheritable modifications.     

Intrapopulation variation in the quality of dandelion seed progeny in zones of chemical and radioactive contamination

Interfamilial variation in metal tolerance and radioresistance of seed progeny from F ₁ plants was studied in the dandelion from cenopopulations growing over several decades in gradients of radioactive or chemical contamination. The progeny from the impact zone of the Eastern Ural Radioactive Trace (EURT) proved to be highly viable but had latent injuries that accounted for a high sensitivity to additional technogenic impact. In the F ₁ generation from the zone of chemical contamination, high seed viability was combined with increased tolerance to additional impact of radiation and heavy metals. No significant differences between responses to challenge with habitual and new factors were revealed in samples from either zone.     

Strategies of adaptation to heavy metal pollution in Deschampsia caespitosa and Lychnis flos-cuculi: Analysis based on dose-response relationship

The response to copper pollution was studied in the vegetative progeny of tufted hair grass (Deschampsia caespitosa (L.) Beauv.) and ragged robin (Lychnis flos-cuculi L.) plants growing together in chronically polluted areas around the Middle Ural Copper Smelter or in background areas. The root elongation test was used, with copper sulfate (0.006–0.51 mg Cu/L) being added directly to the nutrient medium. Using multimodel inference, dose-response curves were plotted for each of 85 maternal plants, and their parameters (effective Cu concentrations and curve slope in the linear segment) were evaluated. The pattern of transformation in dose dependence of root increment upon transition from background to impact populations proved to be basically different in the two species. The curves for L. flos-cuculi showed a parallel shift, with their shape remaining generally unchanged. In D. caespitosa, this transition was accompanied by a decrease in sensitivity to Cu, but tolerance to this metal was found to increase only at the highest concentration range. These results provide evidence for different strategies of adaptation to heavy metal pollution, which are discussed by comparing the physiological and ecological properties of the two species.     

Specific features of the allozyme structure of dandelion populations under conditions of radionuclide and chemical contamination

A study of allozyme spectra has been performed in dandelion cenopopulations growing for a long time under conditions of chemical pollution (the zone of the Nizhnii Tagil Metallurgical Plant, NTMP) or radioactive contamination (the zone of the Eastern Ural Radioactive Trace, EURT). Cenopopulations from the NTMP and EURT zones and from the background area differ significantly in the qualitative and quantitative composition of allozyme phenes. An analysis of clonal diversity has shown that all cenopopulations are phenogenetically unique. The genesis of each cenopopulation proceeded in a specific way: they had different sets of progenitor plants, whose descendants varied genetically in the course of their reproduction and more or less successful colonization of habitats, undergoing selection under the impact of natural environmental factors and technogenic stress. An increased variability of enzyme systems, compared to the sample from the background area, and, as a consequence, reduced clonal diversity may be regarded as a trait common to populations exposed to chemical or radiation stress.     

Estimates of energy expenditures for reproduction in the pied flycatcher Ficedula hypoleuca Pall. in an industrially polluted environment

Energy expenditures for reproduction in local populations of the pied flycatcher in the environs of the Middle Urals Copper Smelter (Revda, Sverdlovsk oblast) have been estimated on the basis of the results of long-term studies (1989?C2008). It is shown that the total energy expenditures per fledgling over the nesting period are 1.2 times higher than in the background area, which is explained by increased energy losses (by a factor of 4.1) resulting from partial mortality of the progeny (eggs or nestlings). Variation in the average energy ??cost?? of one fledgling in the heavily polluted zone is also higher, compared to the background area. Average energy expenditures per fledgling increase in years with cold weather, and the same is observed when the birds lay larger clutches.     

Long-term dynamics of heavy metal concentrations in the food and liver of bank voles (<Emphasis Type="Italic">Myodes glareolus</Emphasis>) in the period of reduction of emissions from a copper smelter

Long-term changes in the contents of heavy metals (Cu, Zn, Cd, Рb) in the food and liver of bank voles (Myodes glareolus) inhabiting areas exposed to pollution from the Middle Ural Copper Smelter (MUCS) in the period of reduction of its emissions (1990–2015). The results show that 50-fold reduction of emissions has not resulted in an equivalent decrease in the dietary and body concentrations of metals: in the impact zone (1–2 km from the MUCS), Cu, Zn, and Pb concentrations remain unchanged, while Cd concentrations have increased twofold by the end of the observation period; in the background zone (20 km), Cu, Zn, and Cd concentrations remain unchanged, while Pb concentrations have decreased by a factor of 1.7–2.5; and no directed changes have been revealed in moderately polluted plots (4–6 km). The accumulation of heavy metals in the animal body depends primarily on the contents of these elements in food and on the system of elementspecific homeostatic barriers providing effective protection from the toxic effect of heavy metals.     

Irregularity in frequency of mast seed years in <Emphasis Type="Italic">Quercus floribunda</Emphasis> a late successional species of Central Himalaya

The mid altitudinal oak, Quercus floribunda forms predominantly evergreen forest in Central Himalaya between 2000–2400 m. It is late successional, mature phase species that has limited regeneration on disturbance prone sites. This oak produces mast seed crops at an interval of 2–3 years. During masting in Q. floribunda the seed fall and germination is upto ten times greater than in normal years, emphasizing the importance of mast year crop in forest maintenance. However, no mast year in this species since the last nine years (1997–2005) is a matter of serious concern. The rise in the summer and winter temperature over a period of 15 years appear to have affected the frequency of masting in this oak. The importance of masting can be adjudged from the fact that 97% of the surviving seedlings m⁻² are of the mast year crop.     

Analysis of rodent populations in technogenically transformed areas (with reference to <Emphasis Type="Italic">Apodemus</Emphasis> (<Emphasis Type="Italic">S.</Emphasis>) <Emphasis Type="Italic">uralensis</Emphasis> from the EURT zone)

It is shown that the response of rodent populations to acute and chronic irradiation depends on its functional structure, i.e., on specific features of animals with two alternative types of ontogenetic development. Upon acute irradiation, sexually immature young of the year (animals with the second type of ontogeny) are most radioresistant. Exposure to chronic irradiation, as in the zone of the Eastern Ural Radioactive Trace (EURT), leads to an increase in the proportion of mature young of the year (animals with the first type of ontogeny), which are the most radiosensitive part of the population. The abundance and fecundity of mice in the impact zone are consistently higher than in the background zone, which improves the adaptive potential of the population. The role of species ecological specialization and configuration of the contaminated zone in the formation of migrant rodent population is emphasized. It is concluded that a high migration activity allows the pigmy wood mouse (a radiosensitive species) to avoid long-term radiation exposure.     

Relationship between morphological disparity and taxonomic diversity in rodent communities in the zone of influence from the Eastern Ural Radioactive Trace in the Southern Urals

To test the hypothesis that morphological disparity increases while taxonomic diversity decreases in a radioactively contaminated environment, the relationship of these parameters was studied in communities (taxocenes) of rodents living in the Southern Urals in the zone of influence from the Eastern Ural Radioactive Trace (EURT) (2003–2008). Young of the year of six rodent species (98 samples) were examined in the background (control) area (0.2 Ci/km²) and in the impact area polluted with radionuclides from the EURT (750 Ci/km²). The dynamics of morphological disparity (MD), assessed with regard to average values of five exterior characters, was compared between the control and impact taxocenes. Taxonomic (taxocenotic) diversity was estimated with the Shannon index (H). Morphological disparity was found to increase significantly at low rodent abundance (in conditionally unfavorable years) and decrease at high abundance, with the value of MD in the impact taxocene being significantly higher. A negative correlation between MD and H was revealed (r = −0.70), in conformity with the above hypothesis. Discordance (difference in direction) of annual changes in the test parameters, with H increasing while MD decreases (or vice versa) was observed in unfavorable years; it can be used as an indicator of conditions unfavorable for rodent taxocenes.     

Toxicity evaluation of sewage sludges in Hong Kong.

Anaerobically digested sewage sludges collected from four wastewater treatment plants located in Sha Tin, Tai Po, Yuen Long, and Shek Wu Hui in Hong Kong were subjected to chemical characterization and toxicity testing to provide preliminary assessment of their suitability for land application. All sewage sludges were slightly alkaline with pH range of 8.3-8.7. Electrical conductivity (EC; 0.69 dS m(-1)) and soluble NH4-N content (996 mg kg(-1)) of sewage sludge from Yuen Long were lower than that of other plants. Concentrations of heavy metals were determined as total, extractable, and water-soluble fraction using mixed acid digestion, DTPA (pH 7.3), and distilled water, respectively. Yuen Long sludge was most polluted with Zn and Cr higher than the pollutant concentration limits listed in Part 503 of USEPA, owing to the effluent coming from the tannery industry. High concentration of Ni was found in sludge from Sha Tin that originated mainly from the electroplating industry. DTPA-extractable Zn contents were high in sludges from Yuen Long (1247 mg kg(-1)) and Shek Wu Hui (892 mg kg(-1)), while 3.7 mg kg(-1) of DTPA-extractable Cr was found in Yuen Long sludge. Metal speciation of sludges showed that Pb was major in residual phase while Cu, Cr, and Ni in organic and residual phases, and Zn did not show any dominant chemical phase. The sludge extracts did not exert significant adverse effect on seed germination of Brassica chinensis (Chinese cabbage), but Yuen Long sludge caused a reduction in root growth. In view of its lower EC and soluble ammonia contents, the high concentration of Zn and Cr in Yuen Long sludge would likely be responsible for this adverse effect on root growth. Therefore, Yuen Long sludge would likely have a more serious impact on soil quality and plant growth as compared to other sludges. This would require further verification from greenhouse and field experiments.     

Variability of biochemical parameters and radiation resistance of the seed progeny of <Emphasis Type="Italic">Descurainia sophia</Emphasis> and <Emphasis Type="Italic">Lepidium apetalum</Emphasis> under exposure to various factors

The physiological and biochemical characteristics of seedlings of Descurainia sophia (Fisch.) and Lepidium apetalum Wild. have been used as examples to demonstrate that long-term exposure of plant populations to environmental stress factors causes adaptive changes in antioxidant and genomic systems that may considerably affect the radioresistance of seed progeny. The resistance to additional acute irradiation of seed progeny of wild plants adapted to different environmental conditions has been found to be determined not only by the combination of antioxidant and DNA-repair protection systems and the vulnerability of the functioning genome, but also by their variability. The data on the relationship of the radioresistance of wild plant populations with physiological and biochemical characteristics and their variability may be used for expert environmental assessment of the state of the biota and prediction of its viability under exposure to abiotic environmental factors.