Fluvial transport and redistribution of Chernobyl fallout radionuclides

Fallout of Chernobyl-derived radionuclides over the UK evidenced marked spatial variation. Relatively high levels were recorded in central Wales, but they declined rapidly to the east and southeast. As a result, the headwaters of the River Severn received substantial inputs of fallout, whereas only low levels were recorded over the middle and lower reaches of its drainage basin. This situation afforded a valuable opportunity to investigate the sediment-associated transport of Chernobyl-derived radiocaesium through the 10 000 km² drainage basin and its redistribution by fluvial processes.Information on the fallout inputs of radiocaesium has been obtained from the sampling of soil inventories across the basin. Measurements of the radiocaesium content of suspended sediment have been made at several sites on the main river over a period extending from before the Chernobyl disaster through to 1988. Concentrations of caesium-137 in the suspended sediment increased by two orders of magnitude immediately after the accident up to 1450 mBq g ^–1, declined rapidly subsequently, but remained almost an order of magnitude greater than the pre-Chernobyl levels throughout the remainder of the period (1986–1988). Downstream redistribution of radiocaesium has occurred as a result of deposition of sediment-associated radiocaesium in channel and floodplain sinks. It is estimated that 0.6% of the total fallout input of Chernobyl-derived caesium-134 has been transported out of the basin during the period 1986–1990. Estimates of channel and floodplain storage of sediment-associated caesium-134 at the time of sampling in 1988 and 1989 account for 0.01% and 0.2% of the total fallout input to the basin respectively.     

Transfer factor of131I from the fallout to human thyroid dose equivalent after the Chernobyl accident

Summary A similar pattern of variation with time in observed maxima of daily dose equivalent rates in human thyroids (TD - µSv·d^–1) and of daily fallout radioactivities (FR - kBq·m^–2) has been found after the Chernobyl accident. An estimate of the time-lag between the maxima in TD lines and the preceding FR peaks was made of about seven days for adult and nine days for juveniles. Applying this time-lag it was possible to estimate transfer factors from the fall-out to thyroid dose equivalent: the highest estimated values were 221 µSv/kBq·m^–2 for adult and 641 µSv/kBq·m^–2 for juvenile thyroids. These values differ from those published by UNSCEAR (United Nations 1988), which have been calculated for various regions of Czechoslovakia, from ingestion and inhalation intake estimates. A broad variation of transfer factor values could be expected to result from such transfer calculations using ingestion and inhalation estimates. The findings also support the concept of a need for prolonged iodine prophylaxy after emissions of radioiodine into the environment.Abbreviations TD dose equivalent rates in thyroids [µSv·d^–1] - FR fall-out radioactivity (-ies) [kBq·m^–2]     

Chernobyl radionuclides outside the boundaries of the USSR. The European continent]

The reports on radiation sequels of Chernobyl disaster outside the country are scanty in the USSR. The present paper meets the lack, reporting the scale and the nature of the radioactive fall-outs outside the USSR. The analysis is made of possible radiological consequences of such fall-outs and the preventive measures taken by the governments of some European countries.     

Strontium fallout from Chernobyl and perinatal mortality in Ukraine and Belarus

Perinatal mortality rates in the regions of Ukraine and Belarus surrounding the Chernobyl site increased in 1987, the year following the Chernobyl accident. The same year, increases of perinatal mortality were also observed in Germany and Poland, and the effect can be associated with the caesium burden in pregnant women. After 1989, there is an unexpected second rise of perinatal mortality in Belarus and Ukraine. This increase is shown to correlate with the strontium content in pregnant women. The findings parallel an increase of perinatal mortality in Germany following the atmospheric bomb tests in the 1950's and 1960's. While the effect from caesium is essentially limited to 1987, the effect from strontium persists until the end of the study period in 1998. The cumulative effect from strontium around Chernobyl outweighs the effect from caesium by at least a factor of 10. This is contrary to the assertion that the caesium content in the Chernobyl fallout was more than 10-times greater than the strontium content. Thus, the dose factor presently used seems to severely underestimate the effect of strontium on perinatal mortality.     

The migration of radionuclides from global fallout in the trophic chains of biogeocenoses in arid zones

Radionuclide (137Cs and 90Sr) content in soil, plants, terrestrial vertebrates and invertebrates has been studied in Kalmyk ASSR, Turkmenian SSR, and Great Gobi Reserve (Mongolia). The content of radionuclides accumulated by wild animals in arid zone biogeocenoses and the patterns of radionuclide migration along food chains have been estimated. 90Sr was found to be involved in biological cycles with participation of soil and terrestrial organisms 3-23 times more intensively than 137Cs.     

Observation of fallout in Hiroshima caused by the reactor accident at Chernobyl

Fallout from the reactor accident at Chernobyl has been surveyed at Hiroshima. gamma-rays from samples of aerosol, rain water and tap water were measured using low-background gamma-ray spectrometers and concentrations of activities were followed. Almost all of the nuclides detected in Europe were observed in Hiroshima. In addition to dominant volatile fission products of 131I, 132Te-132I and 103Ru, long-lived fission products 137Cs, 106Ru-106Rh, 125Sb and activities produced through the (n, gamma) process in the reactor such as 134Cs, 136Cs and 110mAg were observed in relatively high concentrations.     

Transgenerational accumulation of radiation damage in small mammals chronically exposed to Chernobyl fallout

The purpose of this investigation has been the analysis of the long-term development of biological damage in natural populations of a model mammalian species, the bank vole (Clethrionomys glareolus, Schreber), which were chronically exposed to low doses of ionizing radiation over 22 animal generations within 10 years following the Chernobyl accident. The time course of the biological end-points (chromosome aberrations in bone marrow cells and embryonic lethality) was compared with the time course of the whole-body absorbed dose rate from external and internal exposure in the studied populations inhabiting monitoring sites in Belarus with different ground deposition of radionuclides. The yield of chromosome aberrations and, in lesser degree, embryonic lethality was associated with the radionuclide contamination of the monitoring areas in a dose-dependent manner. As a main feature of the long-term development of biological damage under low dose rate irradiation, permanently elevated levels of chromosome aberrations and an increasing frequency of embryonic lethality have developed over 22 animal generations. This contrasts with the assumption that the biological damage would gradually disappear since in the same period of time the whole-body absorbed dose rate decreased exponentially with a half-value time of about 2.5–3 years. Furthermore, gravid females were captured, and their offspring, born and grown up under contamination-free laboratory conditions, showed the same enhanced level of chromosome aberrations. Therefore the authors suggest that, along with the biological damage attributable to the individual exposure of each animal, the observed cellular and systemic effects reflect the transgenerational transmission and accumulation, via genetic and/or epigenetic pathways, of damage attributable to the chronic low-dose rate exposure of the preceding generations of animals. They also suggest that the level of the accumulated transmissible damage in the investigated populations will decrease in future due to the further recession of the chronic exposure and as a consequence of selection processes.     

The main radionuclides and dose formation in fish of the Chernobyl NPP exclusion zone

The results of the researches of spices-specificity, accumulation dynamics and distribution of 90Sr, of 137Cs and of transuranic elements in fish of the Chernobyl NPP exclusion zone are analysed. The data of estimations of absorbed doze rate from incorporated radionuclides for pray fish and predatory species are given. For the fish from the lake of the left-bank floodplain of the Pripyat River the increase of 90Sr specific activity is registered which is presumably connected with the dynamics of the physical-chemical forms of the radionuclide in soils and their wash out in water bodies from the catchment basin. Now about 90% of internal dose rate of fish from closed aquatic ecosystems within the Chernobyl NPP exclusion zone is caused by 90Sr incorporation.     

Segmentary topography and ventilation gradients in human lungs]

Segmentary topography of the air volume was studied by regional electroplethysmography of the lungs. A distinct apical-basal gradient was shown to be present in men tested in supine position, along with the dorsal-ventral gradient; the origin of the apical-basal gradient could not be explained from the point of view of the gravitational mechanism. A possibility of recalculation of the electroplethysmographic index of the percentage of the air content in the lobe of the lung to the regional air volume index in the lungs, and the principal possibility of calculation of the regional total lung capacity index with the help of electroplethysmography was shown.     

The effect on lymphocyte chromosomes of additional radiation burden due to fallout in Salzburg (Austria) from the Chernobyl accident

An investigation has been carried out to determine whether chromosome aberrations in peripheral blood lymphocytes reflect the elevated environmental dose of low-LET ionising radiation, mainly due to radiocesium from Chernobyl fallout, to the population living in Salzburg city. Sixteen volunteers were sampled 1 year after the Chernobyl accident. Two of these persons were also sampled before the accident, and then in 1988 and 1990. The radioactive environment of Salzburg city and the radiation burden of its inhabitants have been frequently determined before and after the accident. The Cs-137 content of the volunteers was measured by whole-body counting. The additional external plus internal radiation doses in the year 1987 to the tested individuals ranged between 15 and 68% of the former normal environmental burden. The aberration frequencies showed a sharp increase of about a factor 6 from the pre-Chernobyl dose rate (0.9. mGy/year) to the post-Chernobyl dose rate (about 2 mGy/year total) but then decreased again with higher additional dose. In the two persons analysed before and up to 4 years after the accident the aberration yield showed a significant increase from 1984/85 to 1987, a decrease in 1988 and a further decrease in 1990. If these last 2 values are plotted against additional dose they fit the curve of the pooled 1987 values. The dose-effect curves revealed the same tendency as we found in various previous investigations and support the assumption that repair enzymes could be triggered by a certain amount of damage to the DNA.     

The state of the reproductive system of several fish species from water bodies polluted with radionuclides during the Chernobyl catastrophe

The state of the reproductive system in several fish species—offspring of individuals exposed to radiation as a result of the catastrophe at the Chernobyl Nuclear Power Plant (CNPP) was studied. Material was collected in water bodies of Ukraine polluted with radionuclides: water cooler of the CNPP (1992, 2002–2004), Lake Glubokoe (2003–2004), Kiev Reservoir, and Teterev River (1997, 1999–2005). It was shown that the total number and the degree of disturbances in gonads of the studied fish species were positively correlated with the levels of pollution of water bodies: in the cleanest water body, Teterev River, the proportion of fish with gonads without considerable deviations was about 78%; in the Kiev Reservoir, 67%; in the water cooler, 51%; and in Lake Glubokoe, 45%. By the number and pattern of gonad anomalies, species specificity in their response to the radiation background was revealed. A smaller degree of damage of sexual cells and gonads in unisexual (triploid) populations of goldfish Carassius auratus reproducing gynogenetically, as compared to bisexual (diploid) populations, was detected. Among postemergency generations of the studied fish species, in all water bodies the number and degree of gonad disturbances were in F_2–4, in Kiev Reservoir and Teterev River, this was most likely accounted for by the phenomenon of prolonged mutagenesis.     

Environmental behaviour of radionuclides deposited after the reactor accident of Chernobyl and related exposures

Several radioecological experiences with isotopes of ruthenium, iodine, caesium and barium, obtained after the reactor accident of Chernobyl, are reported. It was found that for a wet deposition barium was the element with the highest retention on grass. The retention of caesium was lower by a factor of 1.6, retention of iodine by a factor of 2.4 and retention of ruthenium by a factor of 3.5. Former data on the caesium transport in cereals from leaves to grain were confirmed. Depending on the conditions the iodine transfer factor for milk varied between 0.002 and 0.007 d · kg^–1. The caesium transfer factor for milk was (0.003±0.0006) d . kg^–1 and was found to be relatively constant in the years 1986–1988. In 1991, the values were higher by a factor of 2–5. Radioecological model results of whole-body burdens in Southern Bavaria showed a reduction of the caesium ingestion doses due to countermeasures and spontaneous changes of consumption habits in the first 2 months by a factor of 5 and till the end of 1987 by a factor of 1.5. The model results agree well with the range of measured whole-body burdens. One month after the deposition, the external exposures in urban environments due to ruthenium, caesium and barium isotopes were found to be reduced by a factor of 2, compared with open lawns, in the case of iodine the reduction was even a factor of 2.5. External exposures of a population group from the Munich area were determined by thermoluminescence dosimetry. The results are in accordance with the spectral measurements of external dose rates in urban environments.Dedicated to Prof. W Jacobi on the occasion of his 65th birthday     

Delayed assessment of glucose level bioassays using a chemical stabilizer]

We have studied 36 chemical compounds. Moreover bromide 9,10-bismethyltriphenylphosphoniumantracene has been found to stabilize bioassays and preserve their glucose content unchanged for a period of 75-990 days. Due to its use a delayed technique of a quantitative assessment of glucose in biologic objects has been elaborated characterized by universal novelty. It may be used with the aim of studying metabolic processes in the cosmonauts body, atomic submarine crews members of polar, alpine, desert, underwater, space and other expeditions which cannot be accompanied by a biochemical laboratory.     

A method of equalizing the level of DNA sequences of varying amount in a heterogeneous DNA mixture]

A method for the equalization of double-stranded DNA concentrations in the mixture which may be used for equalizing double-stranded cDNA concentrations involves thermal denaturation of the double-stranded DNA mixture followed by reassociation. The initial reassociation rate is Vi = Ki.(single-stranded DNA)2, and by the end of the process the concentrations of the unreassociated molecules for different DNAs should be approximately equal. Using hydroxylapatite chromatography one can separate single-stranded DNAs from double-stranded DNAs and carry out complete single-stranded DNAs reassociation. The new ratio of different double-stranded DNA concentrations would be almost 1.     

The distribution of the radionuclides in the main components of lake ecosystems within the Chernobyl NPP exclusion zone

The results of the studies devoted to the distribution of radionuclides 90Sr, 137Cs, 238Pu, 239 + 240Pu and 241Am in 1998-2003 in main components of Glubokoe Lake and Dalekoe-1 Lake located within Krasnensky flood lands of the Pripyat River (inner exclusion zone of the Chernobyl NPP) were analysed. The data about the radionuclide content in bottom sediments, in water, in seston, in macrozoobenthos (including bivalvia molluscs), in gasteropods molluscs, in higher aquatic plants and in fish are presented.     

An assessment of binary mixture interactions for nine sweeteners

Binary mixtures of acesulfame K, aspartame, sodium cyclamate,fructose, glucose, stevioside, sodium saccharin, sucrose andxylitol were assessed using factorial mixture designs. A simpleadditive model was used to generate predictions for the sweetnessof the mixtures and these predicted responses were comparedto the observed sweetness ratings of the mixtures. It was foundthat the mixtures tended to exhibit superadditivity at low concentrations,additivity at intermediate concentrations and subadditivityat high concentrations. Synergistic and suppressive effectsin the mixtures were evaluated by comparing mixture responsesto the sweetness ratings of ‘self-mixtures’. Self-mixturedata were generated by treating a mixture of a substance withitself as if it were a mixture of two different substances.Synergism was defined as a mixture response that was greaterthan the sweetness of the component self-mixtures, and suppressionwas defined as a mixture response that was less than the sweetnessof the component self-mixtures. Of the 31 binary mixtures studied,18 showed synergism, two showed suppression and 11 did not differsignificantly from their components. It is hypothesized thatmultiple sweetness receptors or release from bitter suppressionmay account for the synergistic effects.     

The role of vegetation in the regulation of fluxes of technogenic radionuclides at different stages after radioactive fallout

In the remote period after the radioactive fallout in the Chernobyl accident, the biological cycle of ¹³⁷Cs in pine forests of the northern forest-steppe zone and in those of Bryanskoe Polesye become essentially different. In the cleaner northern zone with dark-gray forest soil, the ¹³⁷Cs flux to the soil with litterfall exceeds its influx to the vegetation by a factor of 5; i.e., the ¹³⁷Cs cycle differs from that of stable K, the descending flux being still dominant. In the more contaminated Bryanskoe Polesye zone with podzolic illuvial-iron sandy soil, the annual ¹³⁷Cs influx to above-ground vegetation via root uptake exceeds its return to the soil with litterfall, i.e., the ¹³⁷Cs cycle approaches the biological cycle of stable K.     

Isolation and properties of the angiotensin-converting enzyme from human lungs

Using chromatofocusing, an angiotensin-converting enzyme (EC 3.4.15.1) has been isolated from human lung. The procedure allows for 24 300-fold purification of the enzyme. The enzyme specific activity is 36.3 u. per mg protein; Mr as determined by polyacrylamide gel electrophoresis is 150 000. The lung enzyme after solubilization by trypsin treatment was found to be heterogeneous. Four isoforms of the enzyme with pI 5.3, 4.9, 4.8 and 4.6 were identified. The pH-optimum for the enzyme with respect to hippuryl-L-histidyl-L-leucine hydrolysis lies at 8.3; Km = 2.8 mM. The effect of Cl- on the enzyme activity was studied. It was found that the bradykinin-potentiating factor (SQ 20 881) inhibits the human lung angiotensin-converting enzyme (I50 = 1.6 X 10(-8) M).