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Fig. 3. Synergy coefficient Ks(zn) in relation to principal component zn, n=1, 2, 3. All data are normalized to the values of corresponding control group.

For completeness the global synergy coefficient Ksint of combined influence

of low-dose radiation and cadmium is shown in Figure 4. As it is evident from the graphs, chronic influence of these agents in low doses leads to distinctly antagonistic interaction in overall organism status. It may be a further important evidence of complicated nature of adaptation processes in radiation damage.

Fig. 4. Global quantitative estimation of effects (E(A)) and synergy coefficient (Ks(int)) for combined low-dose radiation and cadmium under chronic influence.

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7. Conclusion

On the grounds of the received results, we can make the following conclusions:

ξ The chronicle influence of the low-dose ionizing radiation and cadmium ions shows an antagonistic interaction numerically characterized by the integral synergy

coefficient Ksint R,Cd 1, which is calculated by PCA of 49 morphological and biochemical indices of rat’s liver and intestine.

ξ Increasing of the absorbed dose leads to the initial decreasing of the agents’ antagonism (the effect of the combined action is less detectable for 84-day age group than for 42-day group), and further dose increasing raises it again (the coefficient of antagonism deviates from 1 to a lesser or greater extent correspondingly). We consider such changes in the range of low cadmium and radiation-absorbed dose to be in complete agreement with the scheme of stressadaptation syndrome.

ξ The observed decreasing of antagonism with absorbed dose does not mean the equivalent direct decreasing of effect value itself, as the synergy coefficient is determined only by the effect’s ratio. At the same time, effects themselves can decrease or increase with absorbed dose, as well. Exactly such situation is typical for the experimental data analyzed above (the graphs for effect values in Fig.4 are non-monotone with dose or time duration). Such a behavior, along with mentioned above, is in well agreement with the general concept of the adaptation mechanisms of the damage reparations under conditions of low-dose radiation.

8. References

1.V.G.Petin, V.P.Komarov. Quantitative description of radiosensitivity modification. M., Energoatomizdat, 1989, 192 pp. (In Russian).

2.A.M.Kuzin. Problem of synergy in radiobiology. Acadamy of science of the USSR, Izvestija, ser. Biology. ¹4, pp. 485-502, 1983. (In Russian).

3.T.W.Anderson. An introduction to multivariate statistical analysis. John Wiley&Sons, New York, 1958.

4.H.Martens, T.Naes. Multivariate calibration. John Wiley&Sons, Chichester, 1991.

5.O.V.Volkova, Iu.Eleckij Foundation of histology and histological technique. M., Nauka, pp.25-40, 1982. (In Russian).

6.W.E.Chijsen, M.D.De Jong, C.H.Van Os Dissociation between Ca2+-ATPase and alcaline phosphatase activities in plasma membranes of rat duodenum. Biochem. et biophys. acta. Vol. 599, 2. pp.538-551, 1980.

7.V.Harms, E.M.Wright. Some characteristics of Na+,K+–ATPase from rat intestinal basolateral membranes. J.Membr.Biol., Vol. 53, ¹ 2. pp.119-128, 1980.

8.Modern methods in biochemistry / Ed. V.N.Orehovich. M., Medicina, 1977. (In Russian).

9.A.N.Klimov, N.G.Nikul’chev Lipid and lipoprotein metabolism and its derangement. SP: Piter Kom, 1999. (In Russian).

10.E.B.Burlakova, A.N.Goloschapov, G.P.Jijina, A.A.Konradov. New aspects in regularity of low-dose low-intensity irradiation. Radiation biology. Radioecology. V. 39, ¹1, pp. 26-33, 1999. (In Russian).

11.V.M.Voitsitsky, S.V.Hizhnyak, A.V.Kurashov, O.O.Kysil, N.E.Kucherenko. An estimation of combined effect of ionizing radiation and cadmium by principal component analysis. IV Congress on radiation investigations, Abstr, Vol. II, p.379.Moscow, Nov. 20-24. 2001.

12.L.E.Franks. Signal theory. Prentice-Hall, N.J., 1969.

CHARACTERIZATION AND TREATMENT OF ACTINIDE CONTAMINATED SOILS AND WELL WATERS

J. D. NAVRATIL

Environmental Engineering and Science, Clemson University, 342 Computer Court, Anderson, South Carolina 29625-6510 USA

1. Abstract

Soil and well water contaminated with actinides, such as uranium and plutonium, are an environmental concern at most U.S. Department of Energy sites, as well as other locations in the world. Remediation actions are on going at many sites, and plans for cleanup are underway at other locations. This paper will review work underway at Clemson University in the area of characterization and treatment of soil and water contaminated with actinide elements.

2. Introduction

Actinide contamination in soil and water has been identified at many sites worldwide including the United States. A variety of treatment methods are available to remove actinides from soil and water, and many methods are commercially available. This paper will review some work in progress at Clemson University on actinide contaminated soil remediation methods as well as characterization methods. The Clemson work on inexpensive methods to remove uranium from water will also be highlighted.

3. Soil treatment

In the United States, the Nevada Test Site (NTS) possesses widespread soil contamination caused by deposition of uranium, plutonium and other radionuclides from defence related nuclear test operations. Clean up efforts are ongoing using conventional remediation techniques. However, the U.S. Department of Energy (DOE) desires to obtain technologies that can further reduce risks, reduce clean up costs, and reduce the volume of remaining contaminated soil.

Clemson University and teaming partner Waste Policy Institute, through a cooperative agreement with the National Environmental Technologies Lab in Morgantown, West Virginia, are assisting the NTS in evaluating possible technologies that have the potential of reducing risks and clean-up cost. Physical, chemical and biological treatment processes are being evaluated. Our technology assessment includes the following sub-tasks:

ξ A description of soil contamination problems at the NTS including a description of contaminant distribution, soil characteristics and adhesion/absorption characteristics of contaminants on soil particles.

ξ An evaluation of physical, chemical and biological processes that have potential to remediate radioactive contaminated soils.

ξ Ranking of technologies based on technical merit, potential experience and ease of implementation.

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The removal of actinides from NTS soils has been attempted using various combinations of attrition scrubbing, size classification, gravity based separation, flotation, air flotation, segmented gate, bioremediation, magnetic separation and vitrification [1-6]. Attrition scrubbing was used extensively as a pretreatment step to break up agglomerated materials, to remove surficial coatings from larger soil particles, and hopefully to make the contaminated soil more amenable to processing. Size separation, based on wet sieving of the contaminated soil, showed that the contamination was associated with the smaller particles. Attrition scrubbing and wet sieving of NTS soil was able to achieve a 70% volume reduction.

Gravity-based processes work on the principle of Stokes’ law; heavy particles settle faster than light particles. However, the size of the particle also influences the rate of settling, thus, gravity based separation is not very effective for fine particles, typical of the NTS soils. Gravity and centrifugal separators utilize the terminal velocity of a particle for the basis of separation, which depends on the combination of density and size. Thus, the fine (size) and heavy (density) actinide oxide particles will be separated and report together to the same concentrate product stream with the large (size) and light (density) soil matrix particles.

Flotation separation is highly dependent on using the correct reagent in the slurry, which would permit air bubbles to attach to contaminated mineral grains. More work is needed to identify the best reagents to produce better separations of soil and contaminants. Carrier flotation has the advantage over air flotation of use of a carrier, which is especially important if the contaminant of interest is present at very low concentrations.

The segmented gate system separates contaminated soil from clean soil according to a preset radioactivity criterion. Poor results were obtained in a recent field test of the technology performed at the NTS: only 61% of the plutonium activity ended up in the “concentrate” with a volume reduction of 2:1 (weight of feed to weight of clean).

Bio-leaching of plutonium oxide occurs with sulphuric acid produced from elemental sulphur in the presence of sulphur oxidizing bacteria. This technology is also based on a precipitation of plutonium sulphate complex (PuO2(SO4)34-) as plutonium oxide sulphur (PuO2S) in the presence of sulphate reducing bacteria. Good results of field testing at the NTS were obtained and the technology has been evaluated as promising. The unit processes are based on sound scientific concepts that have been proven in the acid leaching of uranium oxides with sulphuric acid and oxygen, and in the precipitation of metal ions in wetland-treatment of acid-mine drainage.

Early studies with magnetic separation indicated that the magnetic susceptibility of fine soil is very low. Wet magnetic separation was being tested and indications were that wet magnetic separation might work. Although results to date

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have not been encouraging, there is the potential to further optimize treatment and reduce the amount of material that is held up.

Vitrification and fixation are expensive and do not achieve soil volume reduction. It does not meet DOE programmatic goals of volume reduction; instead, it provides only immobilization of the contaminant. However, it is possible that vitrification may be an acceptable form of treatment on certain locations, especially for uranium contaminated soils.

Leaching methods may be more attractive for uranium contaminated soils than plutonium soils. Carbonate leaching at pH above seven has shown to work extremely well to solubilize the uranyl ion as a carbonato complex while not significantly leaching any of the soil constituents [7].

In summary, size separation helps as an initial soil decontamination step and is especially useful for smaller sized particles. But there can be significant variability in contaminant distribution in the soils and any successful treatment process must address this drawback. Attrition scrubbing appears to help although there is limited data to compare results with and without scrubbing – most studies used either one or the other. Carbonate leaching may improve these systems as well as be totally effective as a primary method. None of these processes have been fully optimized, so significant improvement may be realized by more in-depth studies.

4. Water treatment

Naturally occurring uranium has contaminated numerous private domestic water wells in South Carolina at levels exceeding the U.S. Environmental Protection Agency’s (EPA) drinking water standard of 30 µg/L for uranium concentration. This is based on nephro-toxicity, rather than on radiological hazards. Other areas of the U.S., such as California and New Mexico, also have natural uranium in well water that exceeds the EPA standards.

In Simpsonville-Greenville, South Carolina, high amounts of uranium (30 to 9900 µg/L) were found in 31 drinking water wells. The contamination of uranium in the well water was most likely the result of veins of pegmatite, running east of Greenville to southwest of Simpsonville. In addition to the elevated uranium concentration, elevated radon levels have also been discovered. All the wells that have been tested (currently 111) are above 300 pCi/L in radon. The South Carolina Department of Health and Environmental Control (SC DEHC) requested homeowners to discontinue the use of the well water since chronic ingestion of this water may result in an increased risk of cancer. In addition, SC DEHC is beginning a program to test the levels of radon in air in this community.

The purpose of our work at Clemson University was to determine the form of uranium present in the well water and to test the effectiveness of common household treatment devices to remove uranium and radium. Batch tests with activated carbon, iron powder, magnetite, anion exchange resin and cation exchange resin were used to characterize the form of uranium in the drinking water. In the tests, water and the separation materials were first equilibrated, filtered and then analyzed by alpha spectrometry. The results of the batch tests showed that it is possible to remove greater than 90% of the uranium and radium in the drinking water by using any of the sorbants listed above. Simple filtration with a 0.1 µm filter had little to no impact on uranium removal. Testing of two household treatment devices was performed and found not to be totally effective.

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A magnetic field-enhanced filtration/sorption device is also being evaluated for removal of actinides from water [8-10]. The device consists of a column of supported magnetite surrounded by a movable permanent magnet. The mineral magnetite, or synthetically prepared iron ferrite (FeO.Fe2O3), is typically supported on various materials to permit adequate water passage through the column. In the presence of the external magnetic field, enhanced capacity was observed in using supported magnetite for removal of actinides and heavy metals from wastewater. The enhanced capacity is primarily due to magnetic filtration of colloidal and submicron particles along with some complex and ion exchange sorption mechanisms. The loaded magnetite can easily be regenerated by the removal of the magnetic field and use of a regenerating solution.

One inexpensive device for containing supported magnetite is simply some type of static-bed column with screens at the entrance and exit for holding the support in place while permitting the flow of smaller magnetite particles in and out of the column. The first step in operating the column would be to pass a slurry of activated magnetite down the column containing a support material such as glass beads. Once the column is loaded with magnetite, the magnets would be placed around it to hold the magnetite in place. Then water to be treated would be passed upflow through the column until contaminant breakthrough is reached. Then the magnetic field would be removed and an additional amount of fresh magnetite slurry added to the top of the column to displace a portion of loaded magnetie and the captured contaminate particles. Then the magnets would be replaced around the column and more water passed upflow. The spent magnetite could be regenerated or discared depending on the contaminants and operational situation. Discarding the material would be useful for contaminants that sorb strongly onto the adsorbent material (thus perhaps serving as a favourable waste form for final disposal).

In some cases it may be advantageous to have the magnetite bonded to the support and to use a normal fixed-bed column operation with regenerating solution. There are several methods available to adhere or bond the magnetite particles onto supports. For example, crushed glass and glass wool may be mixed with the support in the presence of a solution of a alkali or alkaline hydroxide (this process would also activate the magnetite); heating may also assist the process, as well as raising the temperature to near the melting point of the glass without the solution present. Grinding the glass wool (or waste fiberglass insulation) with the magnetite may also bond the materials, as would the use of silica gel, resins and other bonding adhesives.

Many processes have utilized iron oxides for the treatment of liquid wastes containing radioactive and hazardous metals. These processes have included adsorption, precipitation and other chemical and physical techniques [11-12]. For example, a radioactive wastewater precipitation process includes addition of a ferric hydroxide floc to scavenge radioactive contaminants, such uranium [13-15]. Some adsorption processes for wastewater treatment have utilized ferrites and a variety of iron containing minerals, such as akaganeite, feroxyhyte, ferrihydrite, goethite, hematite, lepidocrocite, maghemite and magnetite. Ferrite is a generic term for a class of magnetic iron oxide compounds. Ferrites posses the property of spontaneous magnetization and are crystalline materials soluble only in strong acid. Besides ferrite treatment, wastewater could also be pretreated with standard flocculation/precipitation and filtration steps to remove gross amounts of actinides from solution. The magnetic filtration/sorption device would then be used as a

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polishing step for the water to remove colloids, small particles and complex ions not removed in the precipitation/filtration steps.

5. References

1.Cost/Risk/Benefit Analysis of Alternative Cleanup Requirements for Plutonium-Contaminated Soils On and Near the Nevada Test Site, DOE/NV-399, US DOE Nevada Operations Office, May 1995.

2.Murarik, T.M., “Characterization, Liberation and Separation of Plutonium at the Nevada Test Site: Safety Shot Residues”, Proceedings of the Soil Decon ’93: Technology Targeting Radionuclides and Heavy Metals, June 16 and 17, 1993, Gatlinburg, TN, ORNL-6769, Oak Ridge National Laboratory, Oak Ridge, TN, September 1993.

3.Cho, Eung Ha, et. Al., Soil Volume Reduction Technologies, Evaluation of Current Technologies, DOE Cooperative Agreement DE-FC26-98FT40396, Deployment Leading to Implementation, Final Report, submitted by West Virginia University to US DOE National Energy Technology Laboratory, July 2000.

4.Heavy Metals Contaminated Soil Project Technical Summary, DOE/EM-0129P, National Technology Transfer Centre, Wheeling, WV, 1994.

5.Misra, M., et. al., “Characterization and Physical Separation of Radionuclides from Contaminated Soils,” Proceedings of the Soil Decon ’93: Technology Targeting Radionuclides and Heavy Metals, June 16 and 17, 1993, Gatlinburg, TN, ORNL-6769, Oak Ridge National Laboratory, Oak Ridge, TN, September 1993.

6.Papelis, et. al., Evaluation of Technologies for Volume Reduction of Plutonium-Contaminated Soils from the Nevada Test Site, DOE/NV/10845-57, US DOE Nevada Operations Office, June, 1996.

7.Bonnema,B.E., Navratil, J.D. and Bloom, R.R., “SOIL*EX Process Design Basis for Mixed Waste Treatment, Proceedings of WM’95, Tucson, AZ (1995).

8.Kochen R.L. and Navratil J. D., U.S. Patent 5,595,666, January 21, 1997, and U.S. Patent 5,652,190, July 29, 1997.

9.Navratil J. D., Kochen R. L. and Ritter J. A., Proceedings of WM’95, Tucson, AZ (1995).

10.Ebner A. D., Ritter J. A. , Ploehn H. J., Kochen, R. L. and Navratil J. D, Sep. Sci. Tech., 34, 1277, 1999.

11.King C.J. and Navratil J. D., Chemical Separations, Litarvan, Denver, 1986.

12.Macasek F. and Navratil J. D., Separation Chemistry, Horwood, New York, 1992.

13.Boyd T. E., Kochen R. L., Navratil J. D., and Price M. Y., Radioactive Waste Manag. Nucl. Fuel Cycle, 42, 195, 1983.

14.Boyd T. E., Cusick M. J. and Navratil J. D., in Li N. N. and Navratil J. D. (Eds.), Recent Developments in Separation Science, Vol. VIII, CRC Press, Boca Raton, FL, 1986.

15.Kochen R. L. and Navratil J. D., Lanthanide/Actinide Research, 2, 9, 1987.

THE ENDOGENIC AND EXOGENIC FACTORS OF THE REALIZATION OF PHENOTYPIC ADAPTATION

A. N. MIKHYEYEV, M. I. GUSCHA, Y. V. SHILINA

Institute of Cell Biology and Genetic Engineering, National Academy of Sciences of Ukraine,

148 Zabolotny st., Kyiv, 03143, UKRAINE

One of actual branches of modern biology is the research of biological objects resistance to extreme environmental factors (low and high temperatures, various types of electromagnetic radiation, drought, hypoxia etc.). In this article the attempt is made to consider some aspects of adaptation problem and, in particular, mechanisms of phenotypic adaptation (PA).

Hardening of plants, change enzyme spectrum of bacteria passing on different growth medium, virulence change of pathogenic bacteria and fungi, which parasite on the hosts with different levels of resistance and at cultivating of pathogens on growth medium in vitro is represented as the most known examples of PÀ. These examples of PA can be continued. So, the lag phase on a growth curve of bacterial culture is frequently defined as the adaptation phase to new growth medium conditions [1]. Under influence of host changes the physiological characteristics of parasite can be shown as virulence increase as a result of passages [2]. The increasing of phytopathogenic bacteria virulence by the passage through the appropriate plants is also a well-known fact and is frequently used for restoration of pathogenicity properties in museum cultures [3]. Plant hardening phenomenon is investigated well enough [4 - 7]. All above-mentioned facts have created empirical an base for transition to a stage of fundamental researches concentrated on disclosing of resistance mechanisms and on a theoretical substantiation of updating of the methodology [8 - 12].

A few definitions of adaptation phenomena are known. At first, the adaptation is necessarily considered as the actual process of the adaptation (process of adaptiogenesis, adaptive response) to changed conditions. For example, temperature hardening (low or high-temperature) is realized not immediately, but gradually, passing through some phases (stages). Second, the adaptation can mean an already generated adaptation state of an object (result of adaptatiogenesis, adaptability, resistance) to the influence of extreme factors in the environment. In other words adaptation in this case is considered as the final result of the process. An example of this aspect of adaptation is the existence of certain current levels of the resistance of biological objects to stressor influence (coldhardiness, radioresistance and so on). The concept « adaptive response» more unequivocally specifies the dynamic character of adaptation.

Thus, the adaptation of biological objects can be considered as the process and the result of their resistance increase to influence of external and, probably, internal stressors.

Stressors are physical, chemical or biological factors, which act on biological system with dose levels that exceed limits of its sensitivity. An example of plants and microorganisms adaptation can be the increase of their resistance to salting, drought, low or high temperatures, xenobiotics, ultra-violet or ionising radiation. Plant organisms also acquire a system of resistance as a reply to the I nfluence of specific or unspecific pathogens There may also be the adaptation of

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plants and microorganisms populations to their coexistence with individuals of other plants or animals species [1, 4, 5, 8, 12-15].

The changes caused by a stressor are appearing in the transition process of a biological object into a temporarily or a constantly new state, which is characterized by the changed resistance level to the next influences. This can be revealed in conditions of repeated (testing, challenge) action of stressor in an acute or prolonged mode. The final or the current result of interaction of the object with the factor (stressor) can be a state of adaptation or desadaptation. In the first case after action of the certain stressor dose an increase of the resistance of a biological object to the subsequent action of that or an other factor is observed. The first factor is referred to as adaptative, and its action transits the object to adaptation state (state of eu-stress by H. Selye) [16]. In the second case the system decreases its resistance level for the next influences, passing into a condition of desadaptation (distress by H. Selye).

The essence of the adaptation phenomenon as a process is the transition of a biosystem under influence of the stressor into a new state: a stress state. In its turn, the transient process is temporary or constant state of the biological object in a condition of the re-regulation of its parameters [4, 17-20]. This condition is represented by phases of hypoand hyperrecovery (hypoand - or hypercompensation). For example, hyperrecovery of growth rate of the main root is observed at gammairradiation of pea seedling in doses about 2 - 5 Gy [21] or at a high temperature treatment [22]. In these phases the biological object can be characterized by increased resistance to repeated influence of the same or an other factor (cross or multiple adaptation) [15, 23-31]. Just the presence of re-regulation state (hyperrecovery in particular) testifies that biological objects are in a adaptation state [13, 26]. Further, if the adaptive response stops, the biological object more or less full restores to the initial values of the parameters. In case of incomplete recovery we deal with an irreversible component of stressor action on the biological object. The state of the increased resistance (adaptation) can be testified as a persistence of the biological system in the phase of hyporecovery (inhibition) of parameters modified by stressor, staying thence in a condition of hyperrecovery (stimulating action, hormesis) [32, 33]. In the first case the increase of resistance is caused by passive mechanisms. For example, the increase of abscisic acid level in root meristem cells after radiation as a stressor promotes a more complete recovery of cells due to lengthening of time necessary for realization of reparation processes [34]. In the second case the biological system, being in hyporecovery state (hypobiosis) [35], has an opportunity to use except of constitutive recovery systems, also induced components. The character of the transition process at PÀ is universal and can have a variable duration [36]. We are obtained results that illustrated this concept (Figure. 1).

Fig. 1. Effect of gamma-irradiation on cell number dynamic Escherichia coli.

The results of the study of the adaptation phenomenon specify that inertia of biological regulation systems lays at its basis. Biological systems during their development and function are characterized by increased or lowered resistance, which arise spontaneously, under influence of internal factors, and are caused by inertia of biological regulation systems. This circumstance allows us to speak of the existence of constitutive processes and results of adaptation, which are brought about under the influence of endogenous factors, and also about the existence of inducible processes of adaptation, which are caused by the action of exogenous factors. It is possible to consider that the induced adaptation is increased constitutive adaptation. It also concerns processes of decrease (reduction) of initial resistance, i.e. desadaptation processes.

One can distinguish the ontogenetic (phenotype modification, epigenetic) adaptation and phylogenetic (genetic) adaptation. An attribute of phenotype adaptation is the increase of resistance in time limited to the ontogenesis period. During ontogenetic adaptation the occurrence of new properties is not related to a change of the primary genome structure, i.e. this type of adaptation is not inherited, and its mechanism is based on epigenetic reorganizations, which can be inherited by non-genetic mechanisms, for example, due to mechanisms of DNA methylation [37]. A first step of adaptation by procaryotae to external stressors is the initiation of DNA transcription by participation of regulator proteins and change of the S-factors [38]. The phylogenetic adaptation is an adaptation, which is characterized by the genetic inheritance of the increased resistance. The base of its mechanism is the inherited change of the primary genome structure owing to direct or indirect action of various physical, chemical and biological stressors. For example genetic adaptation of microorganisms is based on dot and block reorganizations in certain locuses of its genome [39].

The range of the stressor characteristics, in which limits the adaptive response of biological object is possible, refers to as an adaptive zone. It is necessary to distinguish an adaptive zone on a stressor dose and adaptive zone on its capacity. For example, the adaptation to high temperatures is impossible, if their value exceed a threshold of protein coagulation [23].

The stressor can acutely act during a time interval, which should essentially be the less ontogenetic period of object, repeatedly or chronically (in specific case - is constantly). The acute influence can be defined as this type of