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Sambaqui means, in the Tupi language, a hill of shells. The sambaquis are archaeological sites with remains of pre-historical Brazilian occupation. Since the sambaqui sites in the Rio de Janeiro state region are older than 10,000 years, the applicability of CO(2) absorption on Carbo-sorb and (14)C determination by counting on a low background liquid scintillation counter was tested. In the present work, sambaqui shells were treated with H(3)PO(4) in a closed vessel in order to generate CO(2). The produced CO(2) was absorbed on Carbo-sorb. On saturation about 0.6g of carbon, as CO(2), was mixed with commercial liquid scintillation cocktail (Permafluor), and the (14)C activity determined by counting on a low background counter, Packard Tricarb 3170 TR/SL, for a period of 1000 mins to enable detection of a radiocarbon age of 22,400 BP. But only samples with ages up to 3500 BP were submitted to the method because the samples had been collected in the municipality of Guapimirim, in archaeological sambaqui-type sites belonging to this age range. The same samples were sent to the (14)C Laboratory of the Centro de Energia Nuclear na Agricultura (CENA/USP) where similar results were obtained.
The continuous irradiation (connected with the accident on the Chernobyl atomic power plant) by cesium-137 of the dominant species of rodents (Clethrionomys glareolus, Microtus oeconomus) in the forests of Bryansk Province had a deteriorating effect on the state of reproductive organs and on the course of embryogenesis, stimulated the reproduction cycle but inhibited the rate of sexual maturation and increased the death-rate of young animals. These effects resulted in significant ageing of the population. But all these phenomena provoked by radiation are within the limits of rodents adaptive capacities.
The children living in 4 regions of Russia contaminated as a result of the Chernobyl catastrophe were investigated. The control group consisted of the children of 2 regions which did not undergo this influence. The investigations were made 1-3 years after the catastrophe took place. An increase of etiologically non-clear asthenic-vegetative disorders was determined in the regions of radiation contamination. They were observed mainly among the children who had light residual organic cerebral deficiency. The authors cannot exclude the impact of the psychogenic factors.
The average concentrations of naturally occurring radionuclides in drinking water are estimated from recent measurements and are used to estimate the annual effective dose equivalent associated with drinking water due to the different radionuclides. The annual effective dose equivalents are determined from the annual intake of these radionuclides using dosimetric information based on ICRP Publication 30 dosimetric models and cohort analysis considering risk coefficients developed by the U.S. Environmental Protection Agency using data from the report of the Biological Effects of Ionizing Radiation Committee (BEIR III) of the National Academy of Sciences. The resulting contribution from drinking water sources to the annual effective dose equivalent is in the range of 0.002 to 0.05 mSv/y (0.2-5 mrem/yr) for those using community drinking water supplies (approximately 216 million people in the United States). The contribution to the annual effective dose equivalent from 222Rn dissolved in water is in the range of 0.8-30 mu Sv/y (0.08-3 mrem/yr) based on the inhalation pathway following the release of 222Rn from drinking water.
The authors represent summarized data on the time course of incorporated Cs in the population of the Krasnogorsk District of Bryansk Province over the period of June 1986-July 1989. A RIKh-5M device used as a counter of human radiations, its technical data and calibration methods were described. A retrospective analysis has shown that the main accumulation of radionuclides occurred before May 15 1986. The highest rates of Cs clearance from the body were noted in the period of August 1986 till February 1987, the average resultant periods of semiclearance for different populated areas and groups of population were 55-85 days. The ratio of accumulated Cs in children and adults was 0.3, in men and women--1.4. The effectiveness of measures aimed at reducing collective doses of internal irradiation was analyzed.
Genetic effects of irradiation in males of wild house mice which were caught in the region of Chernobyl Nuclear Power Station were studied. The dose rate on the ground surface varied from 0.04 to 200 mR/h of gamma-irradiation. The increasing yield of dominant lethal mutations was only observed in males from the most contaminated sector. Reciprocal translocations were observed in spermatocytes of mice at all the levels of contamination. The rate of reciprocal translocations was relatively low and increased linearly with the elevation of the dose rate. The extent of testis damages increased also, as the dose rate grew. The frequency of abnormal sperm heads, the yield of recessive lethal mutations, litter size and radiosensitivity of the first progeny were not changed, depending on the dose rate.
One of the three goals of the United Nations for sustainable food security is to ensure that all people have access to sufficient, nutritionally adequate, and safe food. Decades of tin mining in the Bitsichi area of the Jos Plateau, Nigeria, have left a legacy of polluted water supplies, impoverished agricultural land, and soil containing abnormally high levels of naturally occurring radioactive elements. In order to ascertain the radiological food safety of the population, different crops that constitute the major food nutritive requirements were collected directly across farmlands in the area. The activity concentrations of (226)Ra, (228)Th, and (40)K were determined in the food and soil samples using gamma-ray spectrometry. Additionally, in situ gamma dose rate measurements were performed on the farms using a pre-calibrated survey meter. The corresponding activity concentrations in the food crops ranged from below detection limit (BDL) to 684.5 Bq kg(-1) for (40)K, from BDL to 83.5 Bq kg(-1) for (226)Ra, and from BDL to 89.8 Bq kg(-1) for (228)Th. Activity concentrations of these radionuclides were found to be lower in cereals than in tubers and vegetables. As for the soil samples, activity concentrations of these radionuclides varied from BDL to 166.4 Bq kg(-1), from 10.9 to 470.6 Bq kg(-1), and from 122.7 to 2,189.5 Bq kg(-1) for (40)K, (226)Ra, and (228)Th, respectively. Average external gamma dose rates were found to vary across the farms from 0.50 +/- 0.01 to 1.47 +/- 0.04 microSv h(-1). Due to past mining activities, the soil radioactivity in the area has been modified and the concentration level of the investigated natural radionuclides in the food crops has also been enhanced. However, the values obtained suggest that the dose from intake of these radionuclides by the food crops is low and that harmful health effects are not expected.
We propose a new formulation to calculate the cosmic microwave background (CMB) spectrum in the Randall-Sundrum two-brane model based on recent progress in solving the bulk geometry using a low energy approximation. The evolution of the anisotropic stress imprinted on the brane by the 5D Weyl tensor is calculated. An impact of the dark radiation perturbation on the CMB spectrum is investigated in a simple model assuming an initially scale-invariant adiabatic perturbation. The dark radiation perturbation induces isocurvature perturbations, but the resultant spectrum can be quite different from the prediction of simple mixtures of adiabatic and isocurvature perturbations due to Weyl anisotropic stress.
(137)Cs and (90)Sr background levels in soil and plant around Tianwan Nuclear Power Plant (NPP) are reported. Eighty-four soil samples and 44 plant samples were collected from March 2000 to April 2002. The samples were analyzed by gamma spectrometry and radiochemical separation procedure to quantify (137)Cs and (90)Sr radioactivities. The concentrations (Bqkg(-1) dry weight) have been observed in the range of 0.6-1.6 for (90)Sr and 1.4-6.9 for (137)Cs in soils, their average values are 1.0+/-0.3 and 4.6+/-1.6, respectively, which are relatively lower than the reported values in neighboring countries. The mean concentrations (in Bqkg(-1) fresh weight except for tea and grass which is expressed in Bqkg(-1) dry weight) of (137)Cs and (90)Sr are 0.1+/-0.03 and 7.7+/-4.1 in pine needle, 0.27+/-0.05 and 3.0+/-1.1 in tea, 0.65+/-0.19 and 2.1+/-0.3 in grass, 0.033+/-0.021 and 0.084+/-0.045 in wheat, 0.019+/-0.01 and 0.23+/-0.06 in China cabbage, and 0.009+/-0.007 and 0.024+/-0.084 in rice, respectively. The pine needle and tea can be regarded as indicator species for (90)Sr and (137)Cs. The soil-to-plant transfer factor (TF) values of (90)Sr and (137)Cs are, respectively, 0.022 and 0.031 for rice, 0.066 and 3.83 for China cabbage, 0.0088 and 0.089 for wheat, and 0.037 and 0.56 for grass.
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The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K cosmic microwave background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the Universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole Ipeak = (197 +/- 6), with an amplitude delta T200 = (69 +/- 8) microK. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favoured by standard inflationary models.
The frequency of genetic disturbances in germ-line and in somatic cells was studied in animals caught in radionuclide-cotaminated areas within the 30-km Chernobyl NPP zone as well as in model experiments in laboratory mice exposed to chronic external gamma-radiation or to the internal action of incorporated radionuclides (131I, 137Cs, 238Pu). The results of genetic and of cytologic analysis of germ-line and somatic cells in the caught or exposed house mice and in laboratory mice after incorporation of radionuclides are presented. An estimation of relative genetic efficiency of the most harmful radionuclides was made.
Virological and immunological examinations were carried out in 52 children aged 4 to 15 living at the Bryansk district territories contaminated with radionuclides after the Chernobyl accident. The persistence of herpes simplex virus (HSV) in the blood was detected by indirect immunofluorescence in 90% of children, in 10% it was confirmed by the virus isolation in vitro in a cell culture. Specific antibodies to HSV-1 and HSV-2 were detected by enzyme immunoassay in 100% examinees, in 50% their titers surpassed those in the control group. Study of the cell-mediated immunity reactions showed increased spontaneous lymphocyte blastogenesis in 46%, a functional defect of lymphocytes upon their nonspecific stimulation with PHA mitogen and increased antigen-dependent capacity of cells to proliferation in 45%, and increased levels of circulating immune complexes in the blood and a tendency to increase of the IgG and decrease of the IgA levels in the blood serum. In addition, a quantitative imbalance was revealed in the T-cell population. Study of interferon production revealed a reduced capacity of blood lymphocytes to produce gamma-interferon and an increased production of alpha-interferon by leukocytes, as well as an increased level of circulating interferon in the serum. These data indicate a decrease of the immune status due to radiation and HSV infection.
One of the problems facing the program in the wake of the Chernobyl accident is the estimation of genetic damage to plants and animals. Special attention was directed to studying the influence of radioactive pollutants at the accident site by means of an appropriate test system, using standard genetic subjects. The present study describes such investigations. Levels of persistent genetic damage in natural populations of Drosophila melanogaster found in the vicinity of the Chernobyl accident site were examined from August 1986 to September 1989. Evidence is presented which indicates a relationship between the levels of radioactive pollution resulting from the Chernobyl accident and increasing genetic damage to exposed populations. The possible reasons for the decrease of mutation frequency observed in 1988 and 1989 are also discussed. Furthermore, evidence is presented which suggests that radiosensitive Drosophila mutants may be particularly sensitive indicators of radioactive pollution.