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Sample records for 210pb spiked soils

  1. Correlation of unsupported 210Pb activity in soil and moss

    The activities of unsupported 210Pb, a naturally occurring radionuclide, were measured in samples of soil and terrestrial mosses collected in Serbia. Considering that clay particles in soil have a high affinity for Pb adsorption, and that mosses usually capture aerosol particles to obtain necessary nutrients, measurable amounts of airborne 210Pb, the daughter of 222Rn, can be registered in both soil and mosses. The objective of the present study was to determine if it is possible to compare the activity of unsupported 210Pb in soil and moss collected at the same sampling site, and to establish if a correlation exists between these measured values. - Highlights: • Samples of the soil and mosses were collected at same location. • Lead-210 was measured in mosses and soil. • Annual depositional flux of 210Pb is determined using 210Pb measured in soil. • Dependence of 210Pb in mosses of 210Pb atmospheric depositional flux can be observed

  2. 210Po and 210Pb in soils and vegetables in Kucuk Menderes basin of Turkey

    In this study concentrations of 210Po and 210Pb radionuclides in soils and vegetables collected from both cultivated and uncultivated agricultural lands of the Kucuk Menderes basin were determined. 210Po and 210Pb activity concentrations of vegetables collected from cultivated lands were found to be slightly higher than those collected from undisturbed lands. The activity concentrations in vegetables were detected between 0.15-9.40Bqkg-1 and 0.23-0.62Bqkg-1 for 210Po and 210Pb, respectively. In the bulk soil cores sampled from phosphate fertilizer-applied agricultural lands, the ranges for activity concentrations of 210Po and 210Pb are 30.10-47.15Bqkg-1 and 31.27-61.53Bqkg-1, respectively. 210Po and 210Pb activity concentrations in soil cores collected from uncultivated soils were also determined for comparison. The annual effective dose equivalents to man from 210Po and 210Pb due to consumption of leafy vegetables are calculated to be 30.51 and 22.73μSva-1, respectively. Likewise root vegetables give a dose equivalent of 22.89μSva-1 from 210Po and 44.77μSva-1 from 210Pb

  3. The Use of Excess 210Pb (210Pbex) as a Soil and Sediment Tracer

    Lead-210 (210Pb) is one of the fallout radionuclides offering the broadest spectrum for environmental applications due to its geogenic origin and relatively long half-life of around 22 years. For more than five decades, 210Pb has been widely used for dating sediments and investigating sedimentation processes. It is only since the 1990s that studies have been using fallout 210Pb for providing information on the magnitude of soil erosion and sedimentation in agricultural landscapes. As it is rapidly and strongly adsorbed at the soil surface, 210Pb has an environmental behaviour similar to 137Cs. The use of fallout 210Pb for documenting soil redistribution rates involves the same advantages and limitations as 137Cs. However, 210Pb can extend the temporal scale, associated with other FRNs measurements, to provide a retrospective assessment of long-term soil redistribution rates over a period of up to 100 years. In addition, since the fallout of 210Pb is continuous, its use does not face the problems associated with short- and medium-lived radioactive soil tracers. This paper summarizes the state-of-the-art related to the main assumptions, the requirements and the limitations which have to be recognised when using this FRN as a soil and sediment tracer. In particular, measurement of fallout 210Pb by gamma spectrometry requires more accurate analytical measurements, as compared to 137Cs, to be performed by skilled staff, and appropriate analytical quality assurance systems. Lessons learned and future research needs in the application of fallout 210Pb are also presented and discussed in this paper. (author)

  4. Estimating emission source of lead using 210Pb specific activity (210Pb/Pb) and zinc as tracers in Slovenian forest soils

    Specific activity of 210Pb (210Pb/Pb) is a good indicator for distinguishing local and remote emission sources of Pb deposited on some forest floors in Slovenia. Another parameter (zinc in soil) gives additional information on possible emission sources and distance of Pb transported from the source. The procedure based on 210Pb activity measurements and non-destructive Pb and Zn determination is rather simple, and not necessary any chemical pre-treatments with strong acids. The soils investigated in this study were collected from several temperate forest sites (Zirovski Vrh, Idrija, Kocevski Rog, Pohorje, Gorisnica, Rakitna, Hotavlje, Otovci, Ptujska gora and Puce) in Slovenia where high level of Pb contamination has been known in some places. Regression analyses of the results suggest an applicability of the proposed procedure for estimating emission sources and atmospheric transportation of Pb. (author)

  5. The speciation and determination of 210Pb and 210Po in soil samples

    A method for speciation and determination of 210Pb and 210Po in soil samples was developed. The speciation was carried out by fractionating the soil samples into 5 fractions which are water soluble or exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and bound to residue. After mineralisation, 10% solution of each fraction was used to spontaneously deposit polonium on a silver disk at 85-90 degree C and pH 1.5 and 210Po was measured by α-spectrometry; the remain solution was used to separate lead by anion-exchange resin and purified by precipitation as PbS and PbSO4, and 210Pb was determined by a low background β-counter. IAEA-327 reference material (soil) has been studied for 210Pb and 210Po speciation. The results show that: (1) the average yields are 88.7±6.4% for 210Pb and 93.8±8.2% for 210Po; (2) if compared to the total 210Pb activity in the sample, 210Pb fractions are 0.95% in exchangeable form, 10.6% bound to carbonates, 14.3% bound to Fe-Mn oxides, 7.00% bound to organic matter, and 67.2% bound to residue or acid soluble, and the corresponding values for 210Po are 0.17%, 0.97%, 21.0%, 0.47% and 77.4%, respectively; and (3) the obtained 210Pb concentration is in good agreement with the recommended value given by IAEA.

  6. 210Pb concentration in soils of west coast of India and its dependence on soil properties

    The paper discusses the results of 210Pb concentration, its vertical profiles and its dependence on physico-chemical properties of the soil in the environment of coastal Karnataka, Kaiga and Goa regions of West coast of India. The concentration was measured by gamma spectrometry using a 41% HPGe detector. Results show that the concentration vary in the range 14.6 - 456.5 Bq Kg-1 with a mean of 149.7 Bq kg-1 in the 0 - 5 cm soil profile. A comparison of the results of the present study with those reported for other normal background regions show that the concentrations observed for some of the locations of Kaiga and Goa are higher. The reasons for the higher concentrations of 210Pb are discussed. The influence of soil pH, density, silt, clay, sand and organic matter contents on retention of this radionuclide is also discussed. (author)

  7. Distribution of 210Pb and 210Po in boreal forest soil

    Vertical distribution and activity contents of 210Pb and 210Po were investigated in forest soils of Scots pine-dominated (Pinus sylvestris L.) stands from seven different locations in Finland. The mean total inventory in the soil profile, up to 20 cm, of 210Pb was 4.0 kBq m-2 (range 3.1-5.0 kBq m-2) and 210Po 5.5 kBq m-2 (range 4.0-7.4 kBq m-2), the organic soil layer containing 45% of the total inventory of both nuclides. In both the organic and the mineral layers the 210Po/210Pb ratio was close to unity indicating a radioactive equilibrium between them. In the litter layer there was, however, a clear excess of 210Po suggesting that polonium is recycled via root uptake from the root zone to the ground surface. The activity concentration (Bq kg-1) of 210Pb clearly correlated with organic matter and the Fe, Al and Mn concentrations in soil indicating that radioactive lead is associated both with humic substances and the oxides of iron, aluminium and manganese. Radioactive lead was also seen to follow the behavior of stable lead. No systematic correlation between polonium and soil properties was seen.

  8. Soil to rice transfer factors for 210Pb: a study on rice grown in India

    India is the second largest producer of rice (Oryza sativa L.) in the world and rice is the essential component of the diet for the majority of the population of India. However, detailed studies aimed at evaluation of radionuclide transfer factors (Fv) for rice grown in India are almost non-existent. This paper presents soil to rice transfer factors for 210Pb for rice grown in natural field conditions on the West Coast of India. A rice field was developed very close to the Kaiga nuclear power plant for the field studies. For a comparative study of radionuclide transfer factors, rice samples were also collected from the rice fields of nearby villages. The soil to un-hulled rice grain 210Pb varied in the range <1.2 x10-2 to 8.1 x 10-1 with a mean of 1.4 x 10-1. The mean values of un-hulled grain to white rice processing retention factors (Fr) was 0.03 for 210Pb. Using the processing retention factors the soil to white rice transfer factor was estimated and found to have the mean value of 4.2 x 10-3. The study has shown that the transfer of 210Pb was retained in the root and its transfer to above ground organs of rice plant is significantly lower. (author)

  9. {sup 137}Cs and {sup 210}Pb inventories in soils and sediments from Chapala Lake (Mexico)

    Ruiz-Fernandez, A.C.; Perez-Bernal, L.H. [Unidad Academica Mazatlan, Instituto de Ciencias del Mar y Limnologia, Universidad Nacional Autonoma de Mexico (Mexico); Sanchez-Cabeza, J.A. [Unidad Academica de Procesos Oceanicos y Costeros, Instituto de Ciencias del Mar y Limnologia, Universidad Nacional Autonoma de Mexico (Mexico); Ontiveros-Cuadras, J.F. [Posgrado en Ciencias del Mar y Limnologia, Instituto de Ciencias del Mar y Limnologia, Universidad Nacional Autonoma de Mexico (Mexico)

    2014-07-01

    Chapala Lake is the largest natural freshwater reservoir in Mexico and it is located in Central Mexico, at 1524 m above sea level. The lake is considered to be fairly anthropized and it has experienced periods of extremely low water level as a result of recent climate change and water extraction. The study of recent manifestations of global change in Chapala Lake requires accurate {sup 210}Pb chronological reconstructions, taking into account the expected variability of sediment accumulation rates by using the Constant Flux model. For a reliable application of this dating model, it is important that {sup 210}Pb flux values in the lacustrine sedimentary record are in correspondence with the local atmospheric fluxes. With the aim to estimate the fluxes of the fallout radionuclides {sup 210}Pb and {sup 137}Cs in the region, sediment and soil cores were collected in the Chapala Lake. Sediment profiles were evaluated and estimated fluxes in sediments and soils were compared. Some geochemical properties (e.g. grain size distribution, organic matter concentration, XRF-derived elemental composition and magnetic susceptibility) were also evaluated to understand how diagenesis changes and sediment provenance can affect the {sup 210}Pb and {sup 137}Cs depth profiles and inventories. Document available in abstract form only. (authors)

  10. 137Cs and 210Pb inventories in soils and sediments from Chapala Lake (Mexico)

    Chapala Lake is the largest natural freshwater reservoir in Mexico and it is located in Central Mexico, at 1524 m above sea level. The lake is considered to be fairly anthropized and it has experienced periods of extremely low water level as a result of recent climate change and water extraction. The study of recent manifestations of global change in Chapala Lake requires accurate 210Pb chronological reconstructions, taking into account the expected variability of sediment accumulation rates by using the Constant Flux model. For a reliable application of this dating model, it is important that 210Pb flux values in the lacustrine sedimentary record are in correspondence with the local atmospheric fluxes. With the aim to estimate the fluxes of the fallout radionuclides 210Pb and 137Cs in the region, sediment and soil cores were collected in the Chapala Lake. Sediment profiles were evaluated and estimated fluxes in sediments and soils were compared. Some geochemical properties (e.g. grain size distribution, organic matter concentration, XRF-derived elemental composition and magnetic susceptibility) were also evaluated to understand how diagenesis changes and sediment provenance can affect the 210Pb and 137Cs depth profiles and inventories. Document available in abstract form only. (authors)

  11. Assessment of soil contamination by 210Po and 210Pb around heavy oil and natural gas fired power plants

    Soil contamination by 210Pb and 210Po around heavy oil and natural gas power plants has been investigated; fly and bottom ash containing enhanced levels of 210Pb and 210Po were found to be the main source of surface soil contamination. The results showed that 210Pb and 210Po in fly-ash (economizer, superheater) is highly enriched with 210Pb and 210Po, while bottom-ash (boiler) is depleted. The highest 210Pb and 210Po activity concentrations were found to be in economizer ash, whereas the lowest activity concentration was in the recirculator ash. On the other hand, 210Pb and 210Po activity concentrations in soil samples were found to be higher inside the plant site area than those samples collected from surrounding areas. The highest levels were found in the vicinity of Mhardeh and Tishreen power plants; both plants are operated by heavy oil and natural fuels, while the lowest values were found to be in those samples collected from Nasrieh power plant, which is only operated by one type of fuel, viz. natural gas. In addition, the levels of surface soil contamination have decreased as the distance from the power plant site center increased. - Highlights: • Fly ash containing 210Po and 210Pb is the main enhancement factor in surface soil. • 210Pb and 210Po in soil are higher inside the campus area than the surrounding areas. • 210Pb and 210Po in ash along the combustion path varied with compartment temperature. • Fly-ash contains 210Pb and 210Po much higher than bottom-ash

  12. Distribution and behaviour of 210Po and 210Pb in soil samples of Goa, south west coast of India

    This paper deals with the distribution and behaviour of 210Pb and 210Po in soil samples of Goa. Soil samples were collected and analysed for 210Po and 210Pb radionuclides using standard radiochemical analytical techniques. The activity of 210Po in surface soil vary from 3.2 Bq kg-1 to 186.2 Bq kg-1 with a mean value of 57.4 Bq kg-1 and that of 210Pb vary from 29.6 Bq kg-1 to 253.4 Bq kg-1 with a mean value of 119.9 Bq kg-1. Depth profile study reveals that the activity of 210Po and 210Pb decreases with the increasing depth. The results obtained from these studies are discussed in detail and compared with the literature values reported for other environs. (author)

  13. Assessment of soil contamination by (210)Po and (210)Pb around heavy oil and natural gas fired power plants.

    Al-Masri, M S; Haddad, Kh; Doubal, A W; Awad, I; Al-Khatib, Y

    2014-06-01

    Soil contamination by (210)Pb and (210)Po around heavy oil and natural gas power plants has been investigated; fly and bottom ash containing enhanced levels of (210)Pb and (210)Po were found to be the main source of surface soil contamination. The results showed that (210)Pb and (210)Po in fly-ash (economizer, superheater) is highly enriched with (210)Pb and (210)Po, while bottom-ash (boiler) is depleted. The highest (210)Pb and (210)Po activity concentrations were found to be in economizer ash, whereas the lowest activity concentration was in the recirculator ash. On the other hand, (210)Pb and (210)Po activity concentrations in soil samples were found to be higher inside the plant site area than those samples collected from surrounding areas. The highest levels were found in the vicinity of Mhardeh and Tishreen power plants; both plants are operated by heavy oil and natural fuels, while the lowest values were found to be in those samples collected from Nasrieh power plant, which is only operated by one type of fuel, viz. natural gas. In addition, the levels of surface soil contamination have decreased as the distance from the power plant site center increased. PMID:24602817

  14. Simultaneous determination of 226Ra and 210Pb in groundwater and soil samples by using the liquid scintillation counter - suspension gel method

    A method for the simultaneous determination of 226Ra and 210Pb in groundwater and soil samples by liquid scintillation counting was developed. Radium and lead were separated together from the samples as Ba(Ra)·PbSO4 co-precipitate, which was centrifuged and dissolved with 0.1 M EDTA solution (pH 9.0). Radium was separated as Ba(Ra)SO4 co-precipitate by adding ammonium sulfate and adjusting the pH of the solution to 4.2. Lead remaining in the solution was separated as PbSO4 precipitate by adding 9 M sulfuric acid. These Ba(Ra)SO4 and PbSO4 precipitates were purified with EDTA solution and used for measurement. To save time and to make counting samples simpler, direct counting of Ba(Ra)SO4 and PbSO4 precipitates instead of the phosphoric acid fusion method was attempted. Ba(Ra)SO4 and PbSO4 precipitates were suspended in the scintillation gel, and measured. Two liquid scintillation cocktails, Instagel[r] XF and UltimaGoldtm AB were used to prepare the counting samples. A mixture of water (40%), Instagel[r] XF (40%) and UltimaGoldtm AB (20%) formed a stable gel. Activities of 226Ra and 210Pb were calculated from the alpha spectrum of Ba(Ra)SO4 and beta spectrum of PbSO4, respectively. The long-term stability of the suspension gel was good. The analytical results of 226Ra and 210Pb in spiked groundwater samples were in good agreement with the known concentrations of 226Ra and 210Pb. The analytical values of 226Ra and 210Pb in the soil reference samples were within 11.5 and 1.6% of the relative error from the reference values, respectively

  15. The fractionation and determination procedures for the speciation of 210Pb and 210Po in soil samples

    A method for speciation and determination of 210Pb and 210Po in soil samples was developed. The speciation was carried out by fractionating the soil samples into five fractions which are water soluble or exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and bound to residue. After mineralisation, 10% solution of each fraction was used to spontaneously deposit polonium on a silver disk at 85-90 deg. C and pH 1.5, and 210Po was measured by α-spectrometry; the remain solution was used to separate lead by anion-exchange resin and purified by precipitation as PbS and PbSO4, and 210Pb was determined by a low background β-counter. The IAEA-327 reference material (soil) was studied for 210Pb and 210Po speciation. The results show that: (1) the average yields are 88.7 ± 6.4% for 210Pb and 93.8 ± 8.2% for 210Po; (2) if compared to the total 210Pb activity in the sample, 210Pb fractions are 0.95% in exchangeable form, 10.6% bound to carbonates, 14.3% bound to Fe-Mn oxides, 7.0% bound to organic matter and 67.2% bound to residue or acid soluble, and the corresponding values for 210Po are 0.17%, 0.97%, 21.0%, 0.47% and 77.4%, respectively; and (3) the obtained 210Pb concentration is in good agreement with the recommended value given by the IAEA

  16. Root uptake of lead by Norway spruce grown on Pb-210 spiked soils

    Hovmand, M.F.; Nielsen, Sven Poul; Johnsen, I.

    2009-01-01

    The root uptake of lead (Pb) by trees and the transfer of Pb by leaf litter deposition to the forest floor were investigated through a pot experiment with Norway spruce. Natural Pb and radio isotopic lead (210Pb) were determined in needles and twigs and in the pot soil spiked with 210Pb. Calculat......The root uptake of lead (Pb) by trees and the transfer of Pb by leaf litter deposition to the forest floor were investigated through a pot experiment with Norway spruce. Natural Pb and radio isotopic lead (210Pb) were determined in needles and twigs and in the pot soil spiked with 210Pb...

  17. Results of an IAEA inter-comparison exercise to assess 137Cs and total 210Pb analytical performance in soil

    Fallout radionuclides (FRNs) such as 210Pb and 137Cs have been widely used to assess soil erosion and sedimentation processes. It is of major importance to obtain accurate analytical results of FRNs by gamma analysis before any data treatment through conversion model and to allow subsequent comparison of erosion and sedimentation rates from different case studies. Therefore, IAEA organized an inter-comparison exercise to assess the validity and reliability of the analytical results of 137Cs and total 210Pb using γ-spectrometry in the various laboratories participating in the IAEA Co-ordinated Research Project on 'Assess the effectiveness of soil conservation measures for sustainable watershed management using fallout radionuclides'. Reference materials were distributed to 14 participating laboratories and, using a rating system, their analytical results were compared to the reference values assigned. In the case of 137Cs, the analytical results were satisfactory with 66% of the laboratories producing acceptable results. Only the sample with low 137Cs activity (2.6±0.2 Bq kg-1) gave less accurate results with more than 25% not acceptable results. The total 210Pb analysis indicated a clear need for corrective actions in the analysis process as only 36% of the laboratories involved in the proficiency test was able to access total 210Pb with occurrence (bias ≤10%). This inter-laboratory test underlines that further inter-comparison exercises should be organized by IAEA or regional laboratories to ensure the quality of the analytical data produced in Member States. As a result of the above-mentioned proficiency test, some recommendations have been provided to improve accurate gamma measurement of both 137Cs and total 210Pb

  18. Results of an IAEA inter-comparison exercise to assess 137Cs and total 210Pb analytical performance in soil.

    Shakhashiro, A; Mabit, L

    2009-01-01

    Fallout radionuclides (FRNs) such as (210)Pb and (137)Cs have been widely used to assess soil erosion and sedimentation processes. It is of major importance to obtain accurate analytical results of FRNs by gamma analysis before any data treatment through conversion model and to allow subsequent comparison of erosion and sedimentation rates from different case studies. Therefore, IAEA organized an inter-comparison exercise to assess the validity and reliability of the analytical results of (137)Cs and total (210)Pb using gamma-spectrometry in the various laboratories participating in the IAEA Co-ordinated Research Project on "Assess the effectiveness of soil conservation measures for sustainable watershed management using fallout radionuclides". Reference materials were distributed to 14 participating laboratories and, using a rating system, their analytical results were compared to the reference values assigned. In the case of (137)Cs, the analytical results were satisfactory with 66% of the laboratories producing acceptable results. Only the sample with low (137)Cs activity (2.6+/-0.2Bqkg(-1)) gave less accurate results with more than 25% not acceptable results. The total (210)Pb analysis indicated a clear need for corrective actions in the analysis process as only 36% of the laboratories involved in the proficiency test was able to access total (210)Pb with occurrence (bias 10%). This inter-laboratory test underlines that further inter-comparison exercises should be organized by IAEA or regional laboratories to ensure the quality of the analytical data produced in Member States. As a result of the above-mentioned proficiency test, some recommendations have been provided to improve accurate gamma measurement of both (137)Cs and total (210)Pb. PMID:18760612

  19. Depth profiles of environmental radionuclides (40K, 226Ra, 210Pb and 137Cs) in temperate forest soils in Germany

    Depth profiles of environmental radionuclides (40K, 226Ra, 210Pb and 137Cs) were investigated in several temperate forest soils in Germany to estimate heterogeneity of the soil horizon of interest. Absolute values of the activity concentrations of these nuclides varied to a large extent depending on the properties of individual forests as well as local geology. Activity concentrations of 40K increased with increasing soil density reflecting that most potassium is contained in mineral components of the soil. The variations in the 40K activity with depth may relate to biological activities in subsoil, such as root uptake of the nutrients. Consequences of bioturbation could be deduced from variability in vertical profiles of the environmental radionuclides like 137Cs and 210Pb. (author)

  20. Assessment of 210Po and 210Pb in lichen, moss and soil around Can coal-fired power plant, Turkey

    This paper deals with determination of 210Po and 210Pb activity concentrations using epigeic moss (Hypnum cupressiforme), bushy soil (fruticose) lichen (Cladonia rangiformis) and surface soil samples in the area around Can coal-fired power plant, northwest Turkey. Mean activity concentrations of 210Po and 210Pb were found to be 303.9 and 425.8 Bq kg-1 for moss, 161.6 and 259.1 Bq kg-1 for lichen, and 79.9 and 91.5 Bq kg-1 for soil samples at dry weight, respectively. We propose that distance and altitude of sampling site may be of significant parameters of distribution of both radionuclides. (author)

  1. 210Pb as a tracer of soil erosion, sediment source area identification and particle transport in the terrestrial environment

    Although 137Cs has been used extensively to study soil erosion and particle transport in the terrestrial environment, there has been much less work using excess or unsupported 210Pb (210Pbxs) to study the same processes. Furthermore, since 137Cs activities in soils are decreasing because of radioactive decay, some locations have an added complication due to the addition of Chernobyl-derived 137Cs, and the activities of 137Cs in the southern hemisphere are low, there is a need to develop techniques that use 210Pbxs to provide estimates of rates of soil erosion and particle transport. This paper reviews the current status of 210Pbxs methods to quantify soil erosion rates, to identify and partition suspended sediment source areas, and to determine the transport rates of particles in the terrestrial landscape. Soil erosion rates determined using 210Pbxs are based on the unsupported 210Pb (210Pbxs) inventory in the soil, the depth distribution of 210Pbxs, and a mass balance calibration (‘conversion model’) that relates the soil inventory to the erosion rate using a ‘reference site’ at which neither soil erosion nor soil deposition has occurred. In this paper several different models are presented to illustrate the effects of different model assumptions such as the timing, depth and rates of the surface soil mixing on the calculated erosion rates. The suitability of model assumptions, including estimates of the depositional flux of 210Pbxs to the soil surface and the post-depositional mobility of 210Pb are also discussed. 210Pb can be used as one tracer to permit sediment source area identification. This sediment ‘fingerprinting’ has been extended far beyond using 210Pb as a single radioisotope to include numerous radioactive and stable tracers and has been applied to identifying the source areas of suspended sediment based on underlying rock type, land use (roads, stream banks, channel beds, cultivated or uncultivated lands, pasture lands, forested lands

  2. Measuring soil loss on forest slopes following harvesting - an approach using 210Pb (excess) to 137Cs inventory ratios

    Measurements of the anthropogenic nuclide 137Cs have been routinely used to measure soil movement on hillslopes. However, 137Cs heterogeneity across the landscape may not result from soil redistribution alone as there is considerable variability in the fallout of 137CS due to rain shadowing and small scale runon - runoff processes. As the deposition of 210Pb (excess) is similarly affected by these processes, taking the ratio of these two nuclides may effectively remove them as sources of variability, and thus provide a more constant benchmark across undisturbed landscapes. In addition to the above, these two nuclides also have different penetration characteristics in undisturbed soils and the core 137Cs/210Pb inventory ratio changes as a function of depth. Consequently, a new method is proposed that involves first determining this change in core ratio at a 'control' location where no soil loss is believed to have occurred, a number of soil samples are then obtained from the disturbed location and the average inventory Pb/Cs ratio of these is calculated. The volume of soil that has been removed from the disturbed site can then be calculated by the extent of depletion of this ratio compared with the ratio curve from the 'control' site. This technique was applied to two harvested forest slopes in N.E. Tasmania which had undergone 'normal' and 'minimal impact' logging procedures. The average core inventory ratio at the 'control' location was 2.4 ± 0.2, compared to the means of 0.72 ± 0.1 (n=10) and 1.62 ± 0.3 (n=10) from the normal and minimal impact sites. These indicate average depth losses of 41 ± 5 mm and 16 ± 3 mm and are equivalent to a nett soil loss of 450 ± 50 and 165 ± 30 t ha-1 respectively from these slopes. It is proposed that this method offers an improvement over using 137Cs alone. 16 refs., 3 figs

  3. Mesoscale variability of vertical profiles of environmental radionuclides (40K, 226Ra, 210Pb and 137Cs) in temperate forest soils in Germany

    Vertical profiles of environmental radionuclides (40K, 226Ra, 210Pb and 137Cs) were investigated in several temperate forest soils in Germany to estimate heterogeneity of the soil horizon of interest. Absolute values of the activity concentrations of these nuclides varied to a large extent depending on the properties of individual forests as well as local geology. Several trends were generally observed independent of the location: (1) Activity concentrations of 40K increased with increasing soil density reflecting that most potassium is contained in mineral components of the soil. The variations in the 40K activity with depth may relate to biological activities in subsoil, such as root uptake of the nutrients. (2) Profiles of 226Ra with depth could be an indicator for evaluating soil heterogeneity within a horizon of interest. They are also useful to estimate anthropogenic 210Pb (210Pbexc) derived from the atmosphere via dry fallout or wet deposition. In several forests, there appeared surface enrichment of 210Pb down to a depth of approximately 10 cm, in which the 210Pb would have come from the atmosphere by combustion of fossil fuels. (3) Depth profiles of 137Cs were roughly divided into three types in which (a) the activity concentration decreased exponentially with soil depth, (b) small amounts of 137Cs existed only in the upper-most layer of the soil (0-5 cm) and (c) 137Cs disappeared at certain depths and appeared again at deeper portions of the soil. Consequences of bioturbation could be deduced from variability in vertical profiles of the environmental radionuclides. It is probable that a site showing an exponential decrease of the 137Cs activity with depth and also having a surface enrichment of 210Pb is not significantly influenced by bioturbation

  4. Soil erosion and sedimentation rates in a small eutrophic lake in southern Chile estimated by 210Pb isotope analysis

    The purpose of this research is to study the effects of historical land use patterns on soil erosion within the San Pedro Lake watershed (Concepcion, VIII Region, Chile). To this end, a geochronological reconstruction of the last 50 years was accomplished by 210Pb isotope and photo-interpretation analysis through the use of GIS. The erosion rate has varied from 0.40 t ha-1 y-1 in 1955 to 0.86 t ha-1 y-1 in 1994. The decrease in native forest was closely coupled with the increase in exotic forestry. The Total Change, meaning the land use change without considering each typology, shows a constant trend indicating a greater degree of anthropogenic intervention. As opposed to the expected, there is no relationship between land use typologies and erosion rates, however it is possible to recognise some degree of dependency between Total Change and erosion values. It is concluded that over the last 50 years the soil erosion processes in the San Pedro Lake watershed may have been more regulated more by land use changes than by land use typologies themselves. (author)

  5. Transfer of {sup 40}K, {sup 238}U, {sup 210}Pb, and {sup 210}Po from soil to plant in various locations in south of Syria

    Al-Masri, M.S. [Atomic Energy Commission of Syria, Damascus, P.O. Box 6091 (Syrian Arab Republic)], E-mail: scientific1@aec.org.sy; Al-Akel, B.; Nashawani, A.; Amin, Y.; Khalifa, K.H.; Al-Ain, F. [Atomic Energy Commission of Syria, Damascus, P.O. Box 6091 (Syrian Arab Republic)

    2008-02-15

    Transfer factors of {sup 40}K, {sup 238}U, {sup 210}Pb, and {sup 210}Po from soil to some agriculture crops in various locations in south of Syria (Dara'a and Assuwaydaa districts) have been determined. Soil and vegetable crops (green pepper, cucumber, tomato, and eggplant), legumes crops (lentil, chickpea, and broad bean), fruit trees (apple, grape, and olives) and cereals (barley and wheat) were collected and analyzed for {sup 238}U, {sup 210}Pb, and {sup 210}Po. The results have shown that higher transfer factors (calculated as Bq kg{sup -1} dry wt. plant material per Bq kg{sup -1} dry wt. soil) for {sup 210}Po, {sup 210}Pb and {sup 238}U were observed in vegetable leaves than fruits and cereals leaves; the highest values of transfer factor (TF) for {sup 238}U were found to be 0.1 for straw of chickpea. Transfer factors for {sup 210}Po varied between 2.8 x 10{sup -2} and 2 in fruits of eggplant and grain of barley, respectively. In addition, several parameters affecting transfer factors of the radionuclides were evaluated. The results can be considered as base values for TF of natural radionuclides in the region.

  6. Distribution of 210Pb and 137Cs in snow and soil samples from Antarctica

    This paper reports some results on natural and artificial radionuclide distribution in snow samples collected at the Priestly Neve-Plateau (inland, 1998 m a.s.l.) and the Vegetation Island (near the coast, 200 m a.s.l.) stations, and in a soil samples from Wood Bay station, both near the Italian Base at Terranova Bay in Antarctica. Data on Pb-210 and Cs-137 in snow samples from an 80 cm deep trench and in granulometric fractions of a soil core are discussed. (author)

  7. 226Ra and 210Pb lixiviation sediments from the region of uranium mine and mill in Pocos de Caldas, contaminated in laboratory by river water and chemical agents, mobility and availability in soils

    Leaching experiments of river bottom sediments, contaminated in the laboratory with 226Ra or 210Pb, by river waters or solutions of inorganic salts and mobility experiments of these radionuclides added to soil columns and leached by a volume of distilled or river water, equivalent to the average annual rain precipitation in the region, are performed. The determination of 226Ra and 210Pb exchangeable fractions in soils contaminated in the laboratory are studied too. The results, as a whole, lead to the conclusion that 226Ra should be considered, potentially, the radionuclide most able to increase the population radiation dose, through the ingestion of contaminated water and foodstuff. (M.A.C.)

  8. Diagenesis and 210Pb

    One of the basic questions when studying cores for historical reconstructions of environmental changes is whether the profiles of 210Pb heavy metals and temporal distributions represent actual or have been affected by diagenetic processes. The term refers to processes occurring in the sediment during and after its formation. Such processes can be physical (such as water loss by compaction in clay sludge), biogeochemical (as the decomposition of organic matter) or biological (eg the ingestion of sediments by infauna.) In this chapter we will refer specifically to diagenetic processes caused by the establishment of a vertical zonation of redox conditions and their effects on concentrations of Fe, Mn and other redox-sensitive metals associated. The redox conditions (defined redox potential Eh) of sediments are primarily controlled by the bacterial decomposition of sedimentary organic matter, and are limited by the rate of supply of organic matter (primary production or other sources) and the rate at that accumulates (rate of accumulation of organic matter). During the bacterial decomposition occurs a sequence of reactions involving a succession of oxidants (or electron acceptors) between which the primary oxidant is O2. However, when the dissolved O2 is consumed and the redox potential has decreased enough to favor the most efficient oxidizing the organic matter decomposition can continue through secondary sources of oxidants (suboxic diagenesis).

  9. Vertical distribution of 210Pb around Uraniferous coal-fired power plant in Western Turkey

    Monitoring of 210Pb in soil, water, sediment and biological materials has been increasing in several pollution studies in recent years. The 210Pb in soils generated in situ by the decay of 226Ra is termed supported 210Pb and is in equilibrium with 226Ra. 210Pb activity in excess of the fraction which is derived from decay of the in situ 226Ra is called unsupported 210Pb. The amount of unsupported or atmospherically derived 210Pb in a soil can be calculated by measuring both the 210Pb and 226Ra activities and subtracting the 226Ra supported 210Pb component from the total 210Pb in the sample. We have determined the deposition rates of 210Pb from the atmosphere in Yatagan Region by measuring their inventories in core samples of cultivated and uncultivated soils.Yatagan is located in Western Turkey in a region where there are three CPPs operating with uraniferous coal. Energy production from coal is one of the major sources of increased natural radioactivity in the atmosphere. Soil samples were stored for a period of 2-3 half-lives (9 - 14 months) of 210Po (t1/2 =138 d) before analysis to allow build-up of 210Pb from 210Pb . The determination of the 210Po activity by alpha-counting provided an indirect measurement of the 210Pb activity. Measurements of 210Po were made through its 5.30 MeV alpha particle emission, using 208Po (5.11 MeV alpha emission, t1/2 = 2.9 yr) as the internal tracer. Measurements were made by silicon surface-barrier detector. The 210Pb activity concentrations in cultivated and uncultivated bulk soil cores varied between 83 Bq kg-1 - 22 Bq kg-1 and 250 Bq kg-1 - 55 Bq kg-1, respectively. (authors)

  10. Comparative advantages and limitations of the fallout radionuclides (137)Cs, (210)Pb(ex) and (7)Be for assessing soil erosion and sedimentation.

    Mabit, L; Benmansour, M; Walling, D E

    2008-12-01

    The fallout radionuclides (FRNs) (137)Cs, (210)Pb(ex) and (7)Be are increasingly being used as a means of obtaining quantitative information on soil erosion and sediment redistribution rates within agricultural landscapes, over a range of different timescales, and they are frequently seen to represent a valuable complement to conventional measurement techniques. The recent development of the (7)Be method has greatly extended the timescale over which FRNs can be used, by permitting assessment of short-term soil erosion linked to individual events and changing soil management practices. This paper aims to review the advantages and limitations of each of the three FRNs and to identify key knowledge gaps linked to their use. In addition, guidelines for selecting the most appropriate FRN and associated approach, in order to deal with a range of spatial and temporal scales and to investigate specific sets of agro-environmental problems, are provided. Key requirements for future work, related to the application of FRNs in soil erosion investigations, are also identified. These include the upscaling of the approach to the catchment scale and a shift from use of the approach as a research tool to a decision support tool. PMID:18947911

  11. Comparative advantages and limitations of the fallout radionuclides {sup 137}Cs, {sup 210}Pb{sub ex} and {sup 7}Be for assessing soil erosion and sedimentation

    Mabit, L. [Soil Science Unit, FAO/IAEA Agriculture and Biotechnology Laboratory, IAEA Laboratories, A-1400 Vienna (Austria)], E-mail: l.mabit@iaea.org; Benmansour, M. [Centre National de l' Energie, des Sciences et des Techniques Nucleaires (CNESTEN), Rabat (Morocco); Walling, D.E. [University of Exeter, Department of Geography, Amory Building, Rennes Drive, Exeter EX4 4RJ (United Kingdom)

    2008-12-15

    The fallout radionuclides (FRNs) {sup 137}Cs, {sup 210}Pb{sub ex} and {sup 7}Be are increasingly being used as a means of obtaining quantitative information on soil erosion and sediment redistribution rates within agricultural landscapes, over a range of different timescales, and they are frequently seen to represent a valuable complement to conventional measurement techniques. The recent development of the {sup 7}Be method has greatly extended the timescale over which FRNs can be used, by permitting assessment of short-term soil erosion linked to individual events and changing soil management practices. This paper aims to review the advantages and limitations of each of the three FRNs and to identify key knowledge gaps linked to their use. In addition, guidelines for selecting the most appropriate FRN and associated approach, in order to deal with a range of spatial and temporal scales and to investigate specific sets of agro-environmental problems, are provided. Key requirements for future work, related to the application of FRNs in soil erosion investigations, are also identified. These include the upscaling of the approach to the catchment scale and a shift from use of the approach as a research tool to a decision support tool.

  12. Transfer of {sup 238}U, {sup 230}Th, {sup 226}Ra, and {sup 210}Pb from soils to tree and shrub species in a Mediterranean area

    Blanco Rodriguez, P. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain); Vera Tome, F. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain)], E-mail: fvt@unex.es; Lozano, J.C. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain); Laboratorio de Radiaciones Ionizantes, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca (Spain); Perez Fernandez, M.A. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain); Area de Ecologia, Universidad Pablo Olavide, Carretera de Utrera km. 1, 41013 Sevilla (Spain)

    2010-06-15

    The soil-to-plant transfer factors of natural uranium isotopes ({sup 238}U and {sup 234}U), {sup 230}Th, {sup 226}Ra, and {sup 210}Pb were studied in a disused uranium mine located in the Extremadura region in the south-west of Spain. The plant samples included trees (Quercus ilex, Quercus suber, and Eucalyptus cameldulensis) and one shrub (Cytisus multiflorus). All of them are characteristic of Mediterranean environments. The activity concentrations in leaves and fruit were determined for the tree species at different stages of growth. For the shrub, the total above-ground fraction was considered in three seasons. For old leaves and fruit, the highest activity concentrations were found in Eucalyptus cameldulensis for all the radionuclides studied, except in the case of {sup 230}Th that presented similar activity concentrations in all of the tree species studied. In every case, the transfer to fruit was less than the transfer to leaves. In the shrub, the results depended on the season of sampling, with the highest value obtained in spring and the lowest in autumn. Important correlations were obtained for {sup 238}U and {sup 226}Ra between the activity ratio in soils with that in leaves or fruit.

  13. Atmospheric depositions of 210Pb and 210Po in Lisbon, Portugal

    The long lived radon daughters 210Pb and 210Po were determined in samples of total surface deposition obtained with collectors continuously operated during 5 years, near Lisbon. The annual 210Pb flux was 66±12 Bqm-2, and the average annual 210Po flux was 8±3 Bq m-2, with an overall 210Po/210Pb activity ratio of 0.15±0.06. The deposition of 210Pb was positively correlated with seasonal rainfall, while 210Po was mainly originated in soil particles re-suspension throughout the year and also in seasonal forest fires. Unusually high 210Po/210Pb activity ratios, higher than unity, were occasionally recorded and the sources and causes are discussed. Long time-series of 210Pb and 210Po deposition fluxes, as presented herein, are rare although essential to test and constrain parameter of the atmospheric Global Circulation Models. (author)

  14. Multi-year Surface Deposition of {sup 210}Pb and {sup 210}Po at Lisbon - Atmospheric Depositions of {sup 210}Pb and {sup 210}Po in Lisbon, Portugal

    Carvalho, Fernando P.; Oliveira, Joao M.; Alberto, G. [Instituto Superior Tecnico/ Campus Tecnologico e Nuclear, Universidade Tecnica de Lisboa, E.N. 10, 2686-953 Sacavem (Portugal)

    2014-07-01

    The long lived radon daughters {sup 210}Pb and {sup 210}Po were determined in samples of total atmospheric depositions obtained with surface collectors continuously operated during 5 years, near Lisbon. The average annual {sup 210}Pb flux was 66±12 Bq m{sup -2}, and the average annual {sup 210}Po flux was 8±3 Bq m{sup -2}, with an overall {sup 210}Po/{sup 210}Pb activity ratio of 0.15±0.06. Direct determination of the {sup 210}Pb atmospheric flux was compared with the {sup 210}Pb excess determined in soil surface layers along with atmospheric depositions of {sup 137}Cs. The deposition of atmospheric {sup 210}Pb was positively correlated with seasonal rainfall, while {sup 210}Po was mainly originated in soil particles re-suspension throughout the year and also in seasonal forest fires. Unusually high {sup 210}Po/{sup 210}Pb activity ratios, higher than unity, were occasionally recorded in atmospheric depositions and the sources and causes are discussed. Long time-series of {sup 210}Pb and {sup 210}Po deposition fluxes, as presented herein are useful to test and constrain parameters of the atmospheric Global Circulation Models. (authors)

  15. Multi-year Surface Deposition of 210Pb and 210Po at Lisbon - Atmospheric Depositions of 210Pb and 210Po in Lisbon, Portugal

    The long lived radon daughters 210Pb and 210Po were determined in samples of total atmospheric depositions obtained with surface collectors continuously operated during 5 years, near Lisbon. The average annual 210Pb flux was 66±12 Bq m-2, and the average annual 210Po flux was 8±3 Bq m-2, with an overall 210Po/210Pb activity ratio of 0.15±0.06. Direct determination of the 210Pb atmospheric flux was compared with the 210Pb excess determined in soil surface layers along with atmospheric depositions of 137Cs. The deposition of atmospheric 210Pb was positively correlated with seasonal rainfall, while 210Po was mainly originated in soil particles re-suspension throughout the year and also in seasonal forest fires. Unusually high 210Po/210Pb activity ratios, higher than unity, were occasionally recorded in atmospheric depositions and the sources and causes are discussed. Long time-series of 210Pb and 210Po deposition fluxes, as presented herein are useful to test and constrain parameters of the atmospheric Global Circulation Models. (authors)

  16. Models dated by 210Pb

    The 210Pbex present in sediments, regardless of their origin, decays following the law of radioactive decay. If the rate of sediment accumulation and flow of 210Pb are constant and there are no redistribution processes of 210Pbex in the sediment, a profile of 210Pbex should be perfectly exponential. Although some of these conditions are not met in all cases and observed profiles are rarely found perfect exponentials, models dated by 210Pb described in this chapter allow to obtain valid dated. Anyway, the models described should be seen as tools of interpretation and the dates obtained as estimates to be corroborated by alternative observations. It is recommended to the reader to go deeper into the topics discussed in this chapter reading references and bibliography at the end. Throughout, the closed system hypothesis must be met. For dating of sediments implies that the radionuclide used is integrated into the matrix tested unaffected by redistribution processes. No cases of mixed sediments or showing evidence of mobility by diagenesis are addressed in this chapter, although we believe that in some circumstances estimates of the accumulation rates are provided but not of the age of formation. Starting with the first published use of 210Pb as a tool dating ice cores, different authors develop model conditions adapted to the dating of sediments. In this chapter we describe the most widely used models, which are based on assumptions about the flow of 210Pbex the sediment surface, the rate of accumulation and concentration of initial210Pbex in surface sediments. The models describing nomenclatures have been different and even contradictory. To facilitate reading of the chapter we propose a nomenclature based on the fundamental assumptions of each model (not in implementation) and have homogenised the nomenclature used. While the model most commonly used for dating sediments is the CF (Constant Flux - Constant Flow), commonly known as CRS (Constant Rate of Supply), the

  17. Example dated with 210Pb

    In this chapter we describe in detail, using an example, the procedure to date a core with the technique of 210Pb using the models described in Chapter 7. Described below, one by one, the spreadsheets containing the information and calculations necessary to complete a profile geochronology of 210Pb core adapted from Gulf of Tehuantepec, Mexico. In this case, the old model obtained from the CA model could not be validated with 137Cs because the peak age of 137Cs is too old (1985 ± 3 years). Moreover, there was an investment of age between sections 2-3 and 3-4 cm because the activity of the lower section is higher than at the top, most likely due to a change in sediment accumulation. The average value of MAR (obtained with the CFCS model: 0.222 ± 0.016 g cm-2 yr-1) is in good agreement with the range obtained with the model MAR CF (0.03 ± 0.02 to 0.30 ± 0.01 g cm-2 yr-1). The chronology obtained with the CF model is well validated with the peak of 137Cs (section 6-7 cm: 1960-1972). SAR profiles and MAR show a progressive increase from the late nineteenth century, due to economic development and population growth in the Gulf of Tehuantepec. This growth, which has altered the coastal marine circulation and sedimentation regimes, had its greatest impact during the past two decades, after the establishment of three major industrial complexes in the region.

  18. Uptake and kinetics of 226Ra, 210Pb and 210Po in big sage brush

    Root uptake of 226Pb and 210Po by mature sage brush was studied using a soil injection method for spiking the soil with minimal root disturbance. The main objective was to measure vegetation concentrations and determine concentration ratios (CR's) due to root uptake as a function of time in mature big sage brush. Concentration ratios obtained in mature vegetation and in steady-state situations may be valuable in assessing the impact of uranium mining and milling. The vegetation was sampled approximately every 3 mo for A 2 y period. Significant levels of activity were detected in the vegetation beginning at the first sampling (81 d after soil injection for 226Ra, 28 d for 210Pb and 210Po). There was an exponential decrease in concentration to an apparent steady state value. Mean values (geometric) of the data pooled over the second year period indicated that steady-state Cr's for 226Ra, 210Pb and 210Po, as determined in mature sage brush, were 0.04, 0.009, and 0.08, respectively. Investigations were also carried out to verify the suitability of soil injection for uptake studies and to evaluate the time dependence of 226Ra leaching from sage brush leaves. The soil injection method was determined to produce, on the average, uptake equivalent to that produce by a uniform soil distribution, however, the variety of uptake for plants growing in injected soil was higher than for plants growing in uniformly contaminated soil. A three compartment mathematical model was formulated to help understand mechanisms of plant uptake and to predict, if possible, the concentration of 226Ra, 210Po in vegetation as a function of time after soil spiking

  19. 210Pb as tracer of environmental processes

    210Pb is a radionuclide naturally occurring radioactive belonging to the chain of 238U. Its half-life is T1/2 = 22.23 ± 0.12 yr. There is some discrepancy in the order of 0.1% of this value and, therefore, not significantly affect the results of the chronology, affected by sources of much greater uncertainty. Assuming that 210Pb can be detected up to about 5 times its half-life, we can expect that 210Pb can provide useful information for the last 100 years or so, although this depends on the analytical techniques used and the precision of the assay. 210Pb plays an important role in the study of the environment as it is present in the atmosphere, lithosphere and hydrosphere. This tracer has been used successfully in the study of biogeochemical processes in the oceans, atmospheric deposition and anthropogenic pollution, sedimentary processes and sediment geochronology.

  20. /sup 210/Pb fluxes in acidified lakes

    The acidification of softwater lakes by atmospheric deposition of strong acids has occurred in several regions of the world; however, the rate of acidification of freshwater systems is generally unknown. The authors have tested the hypothesis that the /sup 210/Pb technique can be used to establish the chronologies of sediments in acidified lakes, with the purpose of establishing the rate of change of the chemical and perhaps biological composition of the water. Sediment cores were collected from four lakes near Sudbury, Ontario, Canada, that either were acidic (pH 4.2 to 4.4) or had been acidic, but were recently neutralized by the addition of calcium carbonate/calcium hydroxide. /sup 210/Pb flux was measured at five sites per lake. The whole lake fluxes in the Sudbury lakes were significantly lower than those of 11 nonacidic lakes -- 250 km to the southeast. Because it is unlikely that lead (Pb) is leached from the sediments, it is hypothesized that acidification results in alteration of the sedimentation mechanism, leading to reduced /sup 210/Pb (and stable Pb) retention in acidic lakes. Therefore, the /sup 210/Pb method is not suitable for establishing sediment chronologies in recently acidified lakes using existing models

  1. The 210Pb technique for dating sediments, and some applications

    The use of 210Pb for dating sediment in time scale 100-150 years is described. Various methods of determination of 210Pb concentration are reviewed and the problem of the initial 210Pb concentration using two models for interpretation of data is discussed. (author)

  2. The average concentrations of 226Ra and 210Pb in foodstuff cultivated in the Pocos de Caldas plateau

    The average concentrations of 226Ra and 210Pb in vegetables cultivated in the Pocos de Caldas plateau, mainly potatoes, carrots, beans and corn and the estimation of the average transfer factors soil-foodstuff for both radionuclides, were performed. The total 226Ra and 210Pb content in the soil was determined by gamma spectrometry. The exchangeable fraction was obtained by the classical radon emanation procedure and the 210Pb was isolated by a radiochemical procedure and determined by radiometry of its daughter 210Bi beta emissions with a Geiger Muller Counter. (M.A.C.)

  3. (210)Po and (210)Pb in medicinal plants in the region of Karnataka, Southern India.

    Chandrashekara, K; Somashekarappa, H M

    2016-08-01

    The activity concentrations of naturally occurring radionuclides (210)Po and (210)Pb were estimated in some selected medicinal plants and soil samples of coastal Karnataka in India. The mean activity concentrations of (210)Po and (210)Pb varied in the range of 4.7-42.9 Bq kg(-1) (dry weight) and 36.1-124 Bq kg(-1) (dry weight) in the soil samples, and 3.3-63.7 Bq kg(-1) (dry weight) and 12.0-406 Bq kg(-1) (dry weight), in the medicinal plant samples, respectively. The plants, Ocimum sanctum L. and Plectranthus amboinicus (Lour.) Spreng had significantly higher activity concentrations of (210)Po and (210)Pb than other species sampled. In spite of disequilibrium between them, these two radionuclides were well correlated in both soil and medicinal plants. PMID:27155527

  4. Preliminary Study on the Use of Radionuclides 137Cs and 210Pb and Spectro radiometry Techniques as Tools to Determine Soil Erosion State

    Radionuclides are largely used as tools for studying and quantifying soil erosion. The global fallout of artificial radionuclides derived from weapons testing (1945-1970) was rapidly and firmly fixed in soil surface horizons. This allowed determining soil erosion by comparing 137Cs inventories at individual sampling points with a reference inventory. This procedure is complemented with the 210Pbuns inventory calculation as an indicator of the local average of radionuclides deposition. Spectro radiometry is implemented to associate soil reflectance measurements to physical and chemical soil properties related to soil erosion processes obtained from laboratory analyses. The methodology applies both instrumental techniques in soil samples from a semiarid agricultural area near to Camarena (Toledo). The resulting inventories obtained for 137Cs and 210Pbexc are similar to the Spanish reference allowing comparation. Spectro radiometry results correlate well with soil properties measured in the laboratory and can be applied to determine these properties more quickly and easily, as well as for integration with gamma spectrometry results. This is a preliminary study to identify soils affected by erosion that is presented as a Master thesis of the Official Master Degree: Agro- Environmental Technology for a Sustainable Agriculture, of the Technical University of Madrid - School of Agricultural Engineers (UPM-ETSI). Coherent and complimentary results are obtained applying both instrumental techniques within this agricultural area.. (Author)

  5. The concentrations of 226 Ra and 210 Pb in food cultivated in Pocos de Caldas

    The aim of this study is to determine the average concentrations of 226 Ra and 210 Pb in vegetables widely cultivated in the region, mainly potatoes, carrots, beans and corn which are the main agricultural products (considering production and human consume) in the region and estimation of the average transfer factors soil-foodstuff for both radionuclides. The total 226 Ra and 210 Pb content in the soil was determined by gamma spectrometry. The exchangeable fraction was obtained by ammonium acetate solution extraction. The 226 Ra was analysed by the classical radon emanation procedure and the 210 Pb was isolated by a radiochemical procedure and determined by radiometry of its daughter 210 Bi beta emissions with a Geiger Mueller counter. (author)

  6. Levels and transfer of 210Po and 210Pb in Nordic terrestrial ecosystems

    Brown, J.E.; Gjelsvik, R.; Roos, Per;

    2011-01-01

    concentrations of the main dose forming radionuclides 210Po and 210Pb in biota from terrestrial ecosystems thus providing insight into the behaviour of these radioisotopes. Samples of soil, plants and animals were collected at Dovrefjell, Central Norway and Olkiluoto, Finland. Soil profiles from Dovrefjell...

  7. Intake of 226Ra, 210Pb and 210Po with food in Poland

    Intake with food and water of 226Ra, 210Pb and 210Po was determined for an adult population in regions of central, northern and northeastern Poland. The content of radionuclides was determined in the daily diet and, in the central region, also in foodstuffs and drinking water. The annual intake with foodstuffs was estimated on the basis of their average annual consumption. The 226Ra intake in northeastern Poland was approximately 17% higher than the overall average, correlating well with the higher concentration of this radionuclide in the soil. The 210Po/210Pb ratio was close to unity in the continental regions, whereas at the Baltic Sea coast it was approximately 1.5. The latter value can be ascribed to a larger consumption of fish for which the 210Po/210Pb ratio was found to be approximately 10. In central Poland the largest intake of 226Ra was with flour and vegetables (contribution approx. 60%), the largest intake of 210Pb was with flour and meat (approx. 50%) and the largest intake of 210Po was with fish (approx. 34%). From the intake and dose coefficient, annual effective doses were calculated. The dose from 210Pb and 210Po was approx. 54 μSv year-1, and the dose from 226Ra was approx. 4 μSv year-1

  8. Intake of {sup 226}Ra, {sup 210}Pb and {sup 210}Po with food in Poland

    Pietrzak-Flis, Z.; Chrzanowski, E.; Dembinska, S. [Department of Radiation Hygiene, Central Laboratory for Radiological Protection, Warsaw (Poland)

    1997-09-06

    Intake with food and water of {sup 226}Ra, {sup 210}Pb and {sup 210}Po was determined for an adult population in regions of central, northern and northeastern Poland. The content of radionuclides was determined in the daily diet and, in the central region, also in foodstuffs and drinking water. The annual intake with foodstuffs was estimated on the basis of their average annual consumption. The {sup 226}Ra intake in northeastern Poland was approximately 17% higher than the overall average, correlating well with the higher concentration of this radionuclide in the soil. The {sup 210}Po/{sup 210}Pb ratio was close to unity in the continental regions, whereas at the Baltic Sea coast it was approximately 1.5. The latter value can be ascribed to a larger consumption of fish for which the {sup 210}Po/{sup 210}Pb ratio was found to be approximately 10. In central Poland the largest intake of {sup 226}Ra was with flour and vegetables (contribution approx. 60%), the largest intake of {sup 210}Pb was with flour and meat (approx. 50%) and the largest intake of {sup 210}Po was with fish (approx. 34%). From the intake and dose coefficient, annual effective doses were calculated. The dose from {sup 210}Pb and {sup 210}Po was approx. 54 {mu}Sv year{sup -1}, and the dose from {sup 226}Ra was approx. 4 {mu}Sv year{sup -1}.

  9. Review of the distribution of 210Pb in the world oceans and 210Pb/226Ra ratio as scavenging tracer

    It was first shown by Rama et al. (1961) that 210Pb has a very short residence time and is remove quickly from the surface waters by suspended particulate matter. Since the first application of the daughter-parent pair in the 238U series (210Pb/226Ra) for deep-scavenging studies by Craig et al (1973), a number of vertical profiles from major ocean basins have been published to investigate the residence time and scavenging rates of 210Pb. The vertical distributions of 210Pb in the deep-ocean vary widely, depending on its supply rates (the atmospheric deposition rate of 210Pb and production from 226Ra) and the intensity of scavenging. The inventories of 210Pb in the 3 distinct zones of the deep ocean (epipelagic, mesopelagic and bathypelagic zones) will be assessed and compared to the total supply rates. The variations in the scavenging intensities in these three zones will be assessed and presented. The inventory of 210Pb in the euphotic zone will be compared to the global atmospheric fallout data and the relative contribution of advection, production from 226Ra and atmospheric depositional input to the 210Pb inventory will be discussed. Evaluation of the distinct differences between different ocean basins in the supply rates as well as the scavenging intensities of 210Pb is assessed and the results will be presented. Using the 210Pb/226Ra ratios in the water column the scavenging residence times obtained for different ocean basins will be compared. The utility of 210Pb-226Ra pair towards studying boundary scavenging, sediment focusing/erosion, and settling velocity of particles based on the water column profiles, sediment trap data and inventories of 210Pb in sediments will also be presented. The utility of 210Pb as a tracer for other lithogenic elements in the marine environment will be discussed and the results will be summarized. (author)

  10. Validation of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb measurements in soil and sediment samples through high resolution gamma ray spectrometry

    Dias, Danila Carrijo da Silva; Silva, Nivaldo Carlos da; Bonifacio, Rodrigo Leandro; Guerrero, Eder Tadeu Zenun [Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas

    2013-07-01

    Radionuclides found in ore extraction waste materials are a great source of concern regarding public health and environmental safety. One technique to determine the concentration of substances is high resolution gamma ray spectrometry using HPGe. Validating a measurement technique is essential to warrant high levels of quality to any scientific work. The Laboratory of Pocos de Caldas of the Brazilian Commission for Nuclear Energy partakes into a Quality Management System project, seeking Accreditation under ISO/IEC 17025 through the validation of techniques of chemical and radiometric analysis of environmental samples from water, soil and sediment. The focus of the Radon Laboratory at LAPOC is validation of Ra-226, Ra-228 and Pb-210 concentration determinations in soil and sediment through a gamma spectrometer system. The stages of this validation process included sample reception and preparation, detector calibration and sample analyses. Dried samples were sealed in metallic containers and analyzed after radioactive equilibrium between Ra-226 and daughters Pb-214 and Bi-214. Gamma spectrometry was performed using CANBERRA HPGe detector and gamma spectrum software Genie 2000. The photo peaks used for Ra-226 determination were 609 keV and 1020 keV of Bi-214 and 351 keV of Pb-214. For the Ra-228 determination a photopeak of 911 keV was used from its short half-life daughter Ac-228 (T1/2 = 6.12 h). For Pb-210, the photopeak of 46.5 keV was used, which, due to the low energy, self-absorption correction was needed. Parameters such as precision, bias/accuracy, linearity, detection limit and uncertainty were evaluated for that purpose. The results have pointed to satisfying results. (author)

  11. Geochemistry of 210Pb in the southeastern, US estuarine system

    This study was an attempt to determine the geochemical behavior of 210Pb in southeastern salt marsh estuaries. As a part of this study the 210Pb dating technique was applied to natural and anthropogenic deposits of the region. 210Pb activity of sediment and water from the Georgia coastal area was measured by alpha spectroscopy. The effects of grain size and carbon content of the sediment on 210Pb concentrations was evaluated and the activity of 210Pb in dissolved and particulate phases of rivers was measured as a function of salinity. Ages and sedimentation rates of sedimentary deposits were also determined for some deposits. 210Pb activity in dissolved and particulate phases of rivers showed no clear trends as functions of salinity. River particulate activities were three to four times higher than dissolved activities. The relationship between 210Pb activity in salt marsh sediments and grain size was highly significant. Direct application of the 210Pb method to date and determine sedimentation rates of natural and anthropogenic deposits was partially successful. The anthropogenic deposits, however, had to be dated on the basis of normalizing 210Pb activities to grain size (% silt and clay) and carbon content

  12. Behavior of 210Pb and 226Ra in tailing samples at Jaduguda

    Several investigation at various parts of the world as well as in different parts of India reported wide variation in activity of 210Pb and 226Ra in environmental matrices. Since 210Pb occurs in decay chain of 226Ra one would expect that in isolated and undisturbed domain the ratio to be nearly unity. However such a ratio is rarely reached. In the actual experience this ratio is influenced to different degree by several environmental parameters such as soil porosity, particle size distribution, and chemical nature of soil and subsurface and surface movement of water. A thorough study on 226Ra and 210Pb ratio can in principle be used as tool to evaluate some environmental parameters in the tailing ponds. A study of natural radioactivity levels including 226Ra and 210Pb in tailing sample around tailing pond area of uranium mining and milling complex located in the Singhbhum regions of Eastern India were undertaken. Tailing pond is covered with the normal background soil known as capping soil. This also reduces the emanation of radon and exposure due 226Ra and its daughter products. Tailings samples were collected after removing the top capping soil. Samples were processed as described by Environmental Measurement Laboratory (EML 1990). Activity concentration of natural 238U series radionuclide like thorium isotopes (234Th and 228Th), lead isotopes (210Pb and 212Pb), radium isotopes (226Ra and 228Ra) and 234mPa were measured using HPGe based high resolution gamma spectrometric technique after attaining secular equilibrium between 226Ra and its daughters. IAEA standard sources RGTh-1 (800 μg/g of 232Th), RGU-1 (400μg/g of 238U), were used for energy and efficiency calibration of the spectrometer in the same geometry (plastic containers of 6.5 cm dia x 7.5 cm ht) as that of the samples. (author)

  13. 226Ra, 210Pb and 210Po in food and in population in Poland

    Content of 226Ra, 210Pb and 210Po was determined in daily diet, foodstuffs and drinking water in various regions in Poland. The annual intake of the radionuclides with foodstuffs for an adult population was estimated on the basis of the average annual consumption. The 226Ra intake was in all the places similar; variations between the samples from a locality were bigger than the differences between various localities. Slightly higher 226Ra intake was observed in Suwalki, evidently being associated with the higher concentration of this radionuclide in the soil. The average 210Po/210Pb ratios was below and close to unity in the daily diet of continental regions, whereas at the Baltic Sea coast it was about 1.5. The latter value can be ascribed to a larger consumption of fish for which the 210Po/210Pb ratio was close to 10. The calculated body burden for an adult man was 1.6 Bq for 226Ra, 6.8 Bq for210Pb and 6.8 Bq for 210Po. (author)

  14. 210Po/210Pb equilibrium ratios in Kaveri river ecosystem

    The behaviour of 210Po, the terminal radioactive member of the naturally occurring 238U series is reported to display markedly interesting movement and accumulation behaviour in the aquatic environment, from that of its parent 210Pb. A study was therefore carried out to investigate the status of 210Po/210Pb activity ratios in Kaveri river ecosystem extending from Karur to Grand Anicut (95 km). The paper presents the activity distribution of 210Po and 210Pb, and the observed 210Po/210Pb activity ratios in water, sediment and certain aquatic organisms (plankton, prawn, bivalve and fish) of the river. The aquatic organisms preferentially accumulated more 210Po than 210Pb. The results also demonstrate that while dissolved 210Po/210Pb ratios in river water are less than unity (0.52 - 0.71), there is a gradual enhancement of these ratios in river sediments (1.31 - 1.67) and plankton (5.2). Significantly higher ratios were recorded in higher species like crustacea, mollusca and fish, with a typical range observed from ∼10 to ∼102. The study thus illustrates the active uptake of 210Po than 210Pb by the biotic components of the river. (author). 11 refs., 1 fig., 3 tabs

  15. A record of atmospheric 210Pb deposition in The Netherlands

    The deposition flux of total atmospheric 210Pb has been measured at two sites in The Netherlands: Texel from 1992 to 1996 and Groningen from 1989 to 1994. With predominant westerly oceanic winds, the annual 210Pb deposition is relatively low as 222Rn, the source for atmospheric 210Pb, is mainly exhaled by the continents. The daily fluctuations in 210Pb deposition are determined by the almost random daily fluctuations in precipitation and the concentration in groundlevel air. The variations in annual 210Pb deposition flux appear to be mainly correlated with the number of heavy rains or thunder storms. This explains the variations in annual deposition at short distance. The average 210Pb deposition at Groningen (1987-1994) is 200 mBq m-2 day-1. The 210Pb deposition over the North Sea is estimated to be 115 mBq m-2 day-1 in the same period. The deposition velocity in Groningen is 1.0 cm s-1, which is similar to measurements in Virginia and Connecticut. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  16. Bioaccumulation of 210Pb in the Kaveri River ecosystem, India

    Data on the concentrations of 210Pb in water, sediment and biota (plankton, weed, snail, bivalve, prawn and fish) of the Kaveri River ecosystem at Tiruchirappalli in South India are presented. The highest level of 210Pb activity was observed in the sediment (15.5 Bq kg-1 dry) and the lowest activity in water (2.7 mBq l-1). The root of the aquatic weed, Eichhornia crassipes, showed a higher activity (1.17 Bq kg-1 wet) than its shoot (0.22 Bq kg-1 wet). Among the biotic components, the shells and bones of animals accumulated higher 210Pb than their tissues and muscle. Among animals, the freshwater mussel, Lamellidens marginalis was identified to accumulate more 210Pb in its soft tissues (0.79 Bq kg-1 wet) and shell (6.55 Bq kg-1 wet) than prawns (muscle 0.65 Bq kg-1 wet; exoskeleton: 1.06 Bq kg-1) wet and fish (muscle: 0.24 Bq kg-1 wet; bone: 1.37 Bq kg-1 wet). The concentration factors (CFs) of 210Pb in biotic components ranged from ∼ 101 to ∼ 103 with higher CFs observed for shells and bones. It is shown that 210Pb undergoes a seasonal variation in surface deposition with minimum values in summer and maximum values in winter. The significance of the results of 210Pb in the abiotic and biotic environment of Kaveri River is discussed. (Author)

  17. Comparison of electrodialytic removal of Cu from spiked kaolinite, spiked soil and industrially polluted soil.

    Ottosen, Lisbeth M; Lepkova, Katarina; Kubal, Martin

    2006-09-01

    Electrokinetic remediation methods for removal of heavy metals from polluted soils have been subjected for quite intense research during the past years since these methods are well suitable for fine-grained soils where other remediation methods fail. Electrodialytic remediation is an electrokinetic remediation method which is based on applying an electric dc field and the use of ion exchange membranes that ensures the main transport of heavy metals to be out of the pollutes soil. An experimental investigation was made with electrodialytic removal of Cu from spiked kaolinite, spiked soil and industrially polluted soil under the same operational conditions (constant current density 0.2 mA/cm(2) and duration 28 days). The results of the present paper show that caution must be taken when generalising results obtained in spiked kaolinite to remediation of industrially polluted soils, as it was shown that the removal rate was higher in kaolinite than in both spiked soil and industrial polluted soil. The duration of spiking was found to be an important factor too, when attempting to relate remediation of spiked soil or kaolinite to remediation of industrially polluted soils. Spiking for 2 days was too short. However, spiking for 30 days resulted in a pattern that was more similar to that of industrially polluted soils with similar compositions both regarding sequential extraction and electrodialytic remediation result, though the remediation still progressed slightly faster in the spiked soil. Generalisation of remediation results to a variety of soil types must on the other hand be done with caution since the remediation results of different industrially polluted soils were very different. In one soil a total of 76% Cu was removed and in another soil no Cu was removed only redistributed within the soil. The factor with the highest influence on removal success was soil pH, which must be low in order to mobilize Cu, and thus the buffering capacity against acidification was

  18. Advantages and limitations of 137Cs, 210Pb and 7Be methodologies for assessing erosion and sedimentation processes

    As demonstrated by around 4000 research papers published, fallout radionuclides 'FRN' (137Cs, 210Pb and 7Be) have been successfully used as soil redistribution tracers for measuring erosion and sedimentation processes. A table presents the advantages and limitations of each of the FRNs as soil redistribution tracers

  19. Atmospheric deposition of 210Po and 210Pb in Malaysian waters during haze events

    Biogenic burning as forest fire phenomena occurring from April to August each year in the Sumatra and Borneo islands are major sources of biogenic uranium–thorium decay series in marine systems. 30 samples were collected during the Ekspedisi Pelayaran Saintifik Perdana 2009 cruise (EPSP 2009 cruise) between 12th June and 1st August 2009 from the Straits of Malacca to the Sulu and Sulawesi Seas to study the effect of haze and the monsoon season on the deposition rate of 210Po and 210Pb in Malaysian waters. All samples were spiked with 1 ml of lead [Pb(NO3)2; 25 mg ml-1] and 0.05 ml of Polonium-209 tracer (26.08 dpm ml-1). 210Po activity was determined by auto plating onto silver foil and counting using an alpha spectrometry system (Canberra model Alpha Analyst with a silicon-surface barrier detector). Lead that was collected via electrodeposition, formed lead sulphate (PbSO4) precipitation. This precipitate was wrapped onto plastic discs and counted for 210Pb beta activity using a gross alpha-beta counting system (Tennelec model LB-5100 low background gas-flowing anti-coincidence alpha/beta counter) after 1 month to allow bismuth ingrowths. The range of 210Po activities varied between 51.08 ± 15.1 and 742.08 ± 220.34 Bq/kg, whereas the activity of 210Pb ranged from 31.10 ± 4.20 to 880.23 ± 123.86 Bq/kg and 210Po/210Pb ratio value varied between sampling stations from 0.19 to 13.77. The contents of 210Po were also statistically positively correlated with the amount of total suspended particulate especially those recorded during heavy haze period events. (author)

  20. 226Ra and 210Pb relationship in solid wastes and plants at Uranium mill tailing

    After the uranium extraction from the ore, the waste residues (tailings) contain several radionuclides in elevated levels comparing to normal soils. Nearly all of the uranium progenies (230Th, 226Ra, 210Pb and 210Po) and the unextracted uranium fraction are present in tailings. These large quantities of tailings may provide a significant source of environmental and food chain contamination. The transfer of radioisotopes between different ecological compartments is frequently evaluated using ratios which relate the radionuclide content in one ecosystem compartment to that of another. For instance, the concentration ratio (CR), i.e., the ratio between radionuclide concentrations in tailings and plants can be evaluated. Radium-226, a long-lived alfa emitter, is a chemical analog of calcium. The 226Ra uptake is similar to calcium in biological and ecological systems. The uptake of 210Pb will follow the same pattern as natural lead. Plants do not require lead but in contrast they require the Ra/Ca group elements. The uptake of lead is mainly a function of the lead tolerance of the plant and the hydrogen ion concentration of the soil. Kalin and Sharma (1982) reported that 226Ra and 210Pb uptake by indigenous species from inactive uranium mill tailings in Canada differ from the uptake of the elements by the same plants growing in soil. Ibrahim and Whicker (1992) reported that tailing acidity tends to enhance radionuclide availability for plant uptake. The transport of radionuclides to foliage and subsequent retention and absorption may play a role in plant contamination. The main goal of this study is to evaluate the 226Ra and 210Pb relationship in tailings and plants growing at uranium mill tailings

  1. Fast procedure for self-absorption correction for low γ energy radionuclide 210Pb determination in solid environmental samples

    Low-energy X and γ radiations (for example of 210Pb: Eγ = 46.5 keV) are effectively self-absorbed even in thin environmental samples, including air filters with captured dust or contaminated soil, as well as in bottom sediment matrixes with limited quantities of the samples. In this paper, a simple method for the direct analysis of 210Pb (T1/2 = 22.3 years) by gamma-ray spectrometry in environmental samples with self-absorption correction is described. The method is based on the comparison of two γ peak activities coming from other natural radionuclides, usually present in environmental samples. We have analyzed the dependence of the self-absorption correction factor for the 210Pb activity on the activity ratios of 911 and 209 keV peaks and 609 and 295 keV peaks coming from nuclides of 238U or 232Th rows, present in typical environmental samples. (author)

  2. The Radiological Impact of 210Pb and 210Po Released from the Iron- and Steel-Making Plant ILVA in Taranto (Italy) on the Environment and the Public

    Guogang Jia

    2013-01-01

    Lead-210 and 210Po are naturally occurring radionuclides. Due to volatile characteristic of lead and polonium, environmental pollution of 210Pb and 210Po released from the coal power plant, steel-making industry and refractory material industry has been an exposure problem for the members of public. In this paper studies on the activity concentrations of 210Po and 210Pb in the raw materials, dust particles, surficial soils and atmospheric particulate samples collected in the area of the Iron-...

  3. A study of 210Pb and 210Po levels in various food components and computation of ingestion dose to the resident community at Kalpakkam, Tamilnadu, India

    210Pb is a member of 238U series and a beta (Emax: 0.017 MeV) and gamma (0.047 MeV) emitting isotope with half-life of 22 years. 210Po, the last radioactive member of 238U series, is an alpha emitter (5.3 MeV) having a half-life of 138.4 days which reportedly delivers a significantly high dose to human population via. ingestion route. According to Clayton and Bradley (1995) about 18% of the average internal dose to the population is due to ingestion of 210Po along with its precursor 210Pb. The main source of 210Pb and 210Po in the environment is 222Rn gas, a daughter product of 226Ra, which diffuses into the atmosphere from rocks and soil where it ultimately decay to 210Pb, 210Bi and then to 210Po in the atmosphere. 210Pb and 210Po attach themselves further electrostatically to aerosol particles, transported back to earth's surface to soil, plant and aquatic environments by dry deposition and washout and both are directly taken up by plants, either from the soil through the root system or by foliar sorption from the air. Besides these radionuclide are also generated in plants from 226Ra assimilated from soil and water. This paper presents the distribution of 210Pb and 210Po activities in food of plant origin and food of animal origin in addition to salt and drinking water collected in and around Kalpakkam. The ingestion dose received due to the intake of 210Pb and 210Po via. dietary sources by the public at Kalpakkam, was computed using the 210Pb and 210Po activity data in the analysed matrices

  4. Leaves of higher plants as biomonitors of radionuclides (137Cs, 40K, 210Pb and 7Be) in urban air.

    Todorović, Dragana; Popović, Dragana; Ajtić, Jelena; Nikolić, Jelena

    2013-01-01

    Leaves of linden (Tilia tomentosa L. and Tilia cordata Mill.) and horse chestnut (Aesculus hippocastanum L.) were analysed as biomonitors of radionuclides in urban air. Samples of soils, leaves and aerosols were collected in Belgrade, Serbia. Activities of (137)Cs, (40)K, (210)Pb and (7)Be in the samples were measured on an HPGe detector by standard gamma spectrometry. "Soil-to-leaves" transfer factors were calculated. Student's t test and linear Pearson correlation coefficients were used for statistical analysis. Differences in local conditions at the sampling sites were not significant, and the mechanisms of the radionuclides' accumulation in both plant species are similar. Ceasium-137 was detected in some of the leaf samples only. Transfer factors for (137)Cs and (40)K were (0.03-0.08) and 1.3, respectively. The concentrations of (210)Pb and (7)Be in leaves were higher in autumn than in spring, and there were some similarities in their seasonal patterns in leaves and in air. Weak to medium correlation was obtained for the (210)Pb and (7)Be activities in leaves and aerosols. Large positive correlation was obtained for the (210)Pb activities in linden leaves and the mean activity in aerosols for the preceding months. Different primary modes of radionuclides accumulation in leaves were observed. Since large positive correlation was obtained for the (210)Pb activity in linden leaves and the mean in aerosols for the preceding months, mature linden leaves could be used as biomonitors of recent (210)Pb activity in air. PMID:22562351

  5. Calibration and measurement of 210Pb using two independent techniques

    An experimental procedure has been developed for a rapid and accurate determination of the activity concentration of 210Pb in sediments by liquid scintillation counting (LSC). Additionally, an alternative technique using γ-spectrometry and Monte Carlo simulation has been developed. A radiochemical procedure, based on radium and barium sulphates co-precipitation have been applied to isolate the Pb-isotopes. 210Pb activity measurements were done in a low background scintillation spectrometer Quantulus 1220. A calibration of the liquid scintillation spectrometer, including its α/β discrimination system, has been made, in order to minimize background and, additionally, some improvements are suggested for the calculation of the 210Pb activity concentration, taking into account that 210Pb counting efficiency cannot be accurately determined. Therefore, the use of an effective radiochemical yield, which can be empirically evaluated, is proposed. 210Pb activity concentration in riverbed sediments from an area affected by NORM wastes has been determined using both the proposed method. Results using γ-spectrometry and LSC are compared to the results obtained following indirect α-spectrometry (210Po) method

  6. {sup 210}Pb and {sup 210}Po in Finnish cereals

    Turtiainen, Tuukka, E-mail: tuukka.turtiainen@stuk.f [STUK, Radiation and Nuclear Safety Authority, P.O. Box 14, 00881 Helsinki (Finland); Kostiainen, Eila, E-mail: eila.kostiainen@stuk.f [STUK, Radiation and Nuclear Safety Authority, P.O. Box 14, 00881 Helsinki (Finland); Hallikainen, Anja, E-mail: anja.hallikainen@evira.f [Finnish Food Safety Authority Evira, Mustialankatu 3, 00790 Helsinki (Finland)

    2011-05-15

    A survey was carried out on the activity concentrations of {sup 210}Pb and {sup 210}Po in cereal grains produced in Finland. The cereal species were wheat (Triticum aestivum), rye (Secale cereale), oats (Avena sativa) and barley (Hordeum vulgare), which account for 90% of the Finnish consumption of cereal products. The survey consisted of 18 flour and 13 unprocessed cereal samples and one hulled grain sample from 22 flour mills. According to the results, the mean {sup 210}Pb/{sup 210}Po concentrations in wheat grains, wheat flour, rye flour, oat grains and barley grains were 0.29, 0.12, 0.29, 0.36 and 0.36 Bq kg{sup -1}, respectively. Combined with the consumption rates of the products, we assess that the mean effective doses from {sup 210}Pb and {sup 210}Po in cereal products for the adult male and female population are 22 and 17 {mu}Sv per year, respectively.

  7. /sup 210/Pb in a tropical coastal lagoon sediment core

    Paez-Osuna, F.; Mandelli, E.F. (Universidad Nacional Autonoma de Mexico, Sinaloa. Inst. de Ciencias del Mar y Limnologia)

    1985-03-01

    Excess /sup 210/Pb in a core from a Mexican Coastal Lagoon, which has no connection with the sea shows a small but measurable decay over the length of the core; when different approaches were compared significant differences in the values for the sedimentation rate are obtained. The best coefficient correlation was calculated when corrected /sup 210/Pb activity for the uneven distribution of organic matter and cumulative inorganic weight is considered. Time frames in the sedimentary column were in agreement between the /sup 210/Pb calculated time and the appearance of shell fragments probably associated with the disturbances caused by the 1961 hurricane Tara. The surface accumulation rate is equivalent to a mean deposition of 262.5 g m/sup -2/ yr/sup -1/ of organic matter which is minor but comparable to some salt marshes of United States.

  8. Efficiency calibration of a planar HPGe spectrometer and measurement method for 210Pb

    A semi-empirical formula was adopted to calibrate an φ43.8 x 5 mm planar HPGe low energy γ and X ray spectrometer for the full energy peak efficiency of environmental samples in the energy range between about 14 and 63 keV. The procedure of calibration was described, and the results of calibration were compared with those obtained through a set of volume reference sources of 241Am and U-Ra (in equilibrium), which were made of mediums of coal, gangue, soil and coal ash. It was found that results from semi-empirical formula and reference sources were consistent within +- 5.5%. Another simple technique for calibration and measurement of 210Pb in environmental samples were also described. The measurement results obtained with the spectrometer calibrated with semi-empirical formula and simple technique for calibration and measurement of 210Pb were agreement within +-7.5% for 210Pb and 238U in gangue samples

  9. Comparison of electrodialytic removal of Cu from spiked kaolinite, spiked soil and industrially polluted soil

    Ottosen, Lisbeth M.; Lepkova, Katarina; Kubal, Martin

    2006-01-01

    Electrokinetic remediation methods for removal of heavy metals from polluted soils have been subjected for quite intense research during the past years since these methods are well suitable for fine-grained soils where other remediation methods fail. Electrodialytic remediation is an electrokinetic...... remediation method which is based on applying an electric DC field and the use of ion exchange membranes that ensures the main transport of heavy metals to be out of the pollutes soil. An experimental investigation was made with electrodialytic removal of Cu from spiked kaolinite, spiked soil and industrially...... polluted soil under the same operational conditions (constant current density 0.2 mA/cm2 and duration 28 days). The results of the present paper show that caution must be taken when generalising results obtained in spiked kaolinite to remediation of industrially polluted soils, as it was shown that the...

  10. Comparison of electrodialytic removal of Cu from spiked kaolinite, spiked soil and industrially polluted soil

    Ottosen, Lisbeth M.; Lepkova, Katarina; Kubal, Martin

    2006-01-01

    remediation method which is based on applying an electric DC field and the use of ion exchange membranes that ensures the main transport of heavy metals to be out of the pollutes soil. An experimental investigation was made with electrodialytic removal of Cu from spiked kaolinite, spiked soil and industrially......Electrokinetic remediation methods for removal of heavy metals from polluted soils have been subjected for quite intense research during the past years since these methods are well suitable for fine-grained soils where other remediation methods fail. Electrodialytic remediation is an electrokinetic...

  11. Dual-core mass-balance approach for evaluating mercury and210Pb atmospheric fallout and focusing to lakes

    Van Metre, P.C.; Fuller, C.C.

    2009-01-01

    Determining atmospheric deposition rates of mercury and other contaminants using lake sediment cores requires a quantitative understanding of sediment focusing. Here we present a novel approach that solves mass-balance equations for two cores algebraically to estimate contaminant contributions to sediment from direct atmospheric fallout and from watershed and in-lake focusing. The model is applied to excess 210Pb and Hg in cores from Hobbs Lake, a high-altitude lake in Wyoming. Model results for excess 210Pb are consistent with estimates of fallout and focusing factors computed using excess 210Pb burdens in lake cores and soil cores from the watershed and model results for Hg fallout are consistent with fallout estimated using the soil-core-based 210Pb focusing factors. The lake cores indicate small increases in mercury deposition beginning in the late 1800s and large increases after 1940, with the maximum at the tops of the cores of 16-20 ??g/m 2year. These results suggest that global Hg emissions and possibly regional emissions in the western United States are affecting the north-central Rocky Mountains. Hg fallout estimates are generally consistent with fallout reported from an ice core from the nearby Upper Fremont Glacier, but with several notable differences. The model might not work for lakes with complex geometries and multiple sediment inputs, but for lakes with simple geometries, like Hobbs, it can provide a quantitative approach for evaluating sediment focusing and estimating contaminant fallout.

  12. Size distribution measurements of stable Pb and 210Pb

    High volume impactor measurements were taken to define the particle size distribution of atmospheric stable Pb and 210Pb. This was done in an effort to establish if a particle size effect could be responsible for the differences in wet and dry deposition values of stable Pb and 210Pb. Duplicate impactor tests were run on the roof of the Environmental Measurements Laboratory (EML) and at the Regional Baseline Station in Chester, NJ, to determine the feasibility of collecting flow controlled impactor samples over extended sampling periods. The test results indicate that 210Pb is associated more with smaller particles than is the stable Pb (63% vs 53%, on the average for particles less than 0.58 μm). This difference, although not large, is beyond the experimental error. The duplicate samples gave results that are in good agreement. The differences observed between the total air concentrations at the urban and rural sites are as expected, since 210Pb has a natural source while Pb is of anthropogenic origin

  13. Radiometric evaluation of the {sup 210}Pb in the estuary of the SUAPE Pole in the State of Pernambuco

    Carneiro, Paula Frassinetti P.; Antonio Filho, Joao; Mendonca, Keyla Mary C., E-mail: jaf@ufpe.com [Departamento de Energia Nuclear (DEN/UFPE), Recife, PE (Brazil); Carvalho, Wellington S. [Faculdade Integrada de Pernambuco (FACIPE), Recife, PE (Brazil)

    2011-07-01

    Nowadays there is a growing interest in the study of natural radioactivity levels, mainly of radionuclide {sup 210}Pb present in the environment. The environmental radioactivity control is of extreme importance for attainment of information on the exposition of humans and vegetables the potential sources in natural radioactive occurrences. Industrial processes involving mining and extraction and production of oil foster concentration of radionuclides, contributing to the occurrence of what is known as TENORM Technologically Enhanced Naturally Occurring Radioactive Material. This work aims to assess the environmental radiological impact on the Estuarine Region of the SUAPE Industrial Pole, due to the installation of an oil refinery and the consequent introduction on the environment of natural radioactive materials from other regions. For this, were determined the concentrations of {sup 210}Pb in samples de soil, sediments, roots and levels of fen and fishes in the region above reported, these data will serve of parameters of reference for a radiometric evaluation on future radioecology impacts caused by the functioning of the refinery of SUAPE oil. To determine the concentration of {sup 210}Pb was used the Ionic Resin Exchange method, for in such a way, the detector was used alpha-beta. Concentrations of {sup 210}Pb in the soils, sediments, roots and levels of fen samples vary respectively from 27 {+-} 2 to 60 {+-} 5, from 18 {+-} 5 to 60 {+-} 6, from 65 {+-} 2 to 117 {+-} 3, from 217 {+-} 6 to 239 {+-} 7 Bq.kg-1. Concentrations of the {sup 210}Pb in samples of some species of fish found in the studied region, such as Mullet, Salema, Catfish and Carapitinga, was also determined varying from 26 {+-} 11 to 62 {+-} 6 Bq.kg-1. The results obtained in the samples of soils, sediments, roots of fen e fishes showed that the concentrations of {sup 210}Pb in the environment are normal for the patterns of the area and are in accordance with data the found ones in literature

  14. Characteristics of U-pattern distribution of high-concentration 210Pb in surface air at central Guizhou, China

    WAN Guojiang; YANG Wei; WANG Shilu; WAN Enyuan; WU Fengchang; S.N.LEE; WANG Changsheng; HUANG Ronggui

    2005-01-01

    A better understanding of the variation of 210Pb concentrations in the surface air is the key to trace lake sedimentation and catchment erosion, to establish and validate the global diffusion model of contaminants, and to assess the impact of natural radiation on the ecological system. Basing on the study progresses of the sedimentation, the atmospheric model and the unique environmental background in the Yunnan-Guizhou Plateau, and starting from December 20, 2001, we made use of a 500 NE Type aerosol sampler to collect filter samples, once a week in the past consecutive two years, in the surface air at Mt. Guanfeng, Guiyang City, China. Synchronous detailed γ-energy spectrometric observations of 210Pb concentrations at both Chinese and U.S. laboratories have shown that the average monthly 210Pb concentration displays a regular U-patterns distribution of annual variations, with high values appearing in winter and low values in late spring and summer. The average annual 210Pb concentrations are estimated to be 2.77±0.63 mBq/m3, about 4 times the average maximum concentrations reported from quite a number of monitoring stations throughout the world. The possible factors affecting the sources of 210Pb in the surface air in the central part of Guizhou Province are: Release of 222Rn from the U-Ra series enriched in the soils; chemical weathering of carbonate rocks; the exploitation, processing and utilization of coal and phosphorous resources. The principal factor controlling the high 210Pb concentrations in the surface air in the central Guizhou and their annual U-pattern distribution is the release of 222Rn. The average monthly 210Pb concentrations show a good negative power- function relationship with increasing precipitation and also show a good negative linear-function relationship with the rise of air temperature in month grouping. Group No.1 (June to November) reflects a relatively low release of 222Rn from soils in relatively high temperature seasons; Group No

  15. Transfer of 226Ra and 210Pb to forage and milk in a Brazilian high natural radioactivity region

    The Pocos de Caldas plateau, where the Brazilian uranium mine and mill facilities are located, is a natural high radioactivity region. A study has been carried out in order to assess the environmental transport of the natural radionuclides in the region. The present work is concerned with the transfer of 226Ra and 210Pb to forage and milk. Similar concentrations for both radionuclides were found in soil samples. In forage 210Pb concentrations are one order of magnitude higher than those of 226Ra, however, the milk samples presented higher values for 226Ra concentrations. The average forage to milk concentration factors are of the order of 10-4 d.l-1 for 226Ra and 10-5 d.l-1 for 210Pb. Regarding transfer mechanisms, the results suggest the foliar deposition as the main pathway for 210Pb uptake by the forage. In contrast, for 226Ra the root uptake appears as the main transfer pathway. (author)

  16. Transfer analysis of 210Po and 210Pb in the terrestrial environment

    The transfer of 210Po and 210Pb between various compartments in the terrestrial environment has been analysed by using published data. The average activity concentration of 210Po in dry soil is 61 ± 14 Bq.kg-1 (median 44 Bq.kg-1). Ground water concentrations of 210Po in drilled wells might be as high as 6.5 Bq/l. But in regular drinking water it is just about 3-5 mBq/l. The uptake of radionuclides from soil to plant is usually given as the ratio of dry matter radionuclide-activity concentrations of plant (ACplant) and soil (ACsoil) respectively. This ratio is called the soil transfer factor: STF = ACplant/ACsoil. The soil transfer factor varies widely between various types of crops with an average of about 0.056±0.003. The activity concentrations in leafy plants are, however highly affected by the atmospheric deposition of 210Pb and 210Po. By comparing the activity concentrations in plants grown on an open field with those grown on a field sheltered by a polyethylene tent, it has been possible to estimate a deposition transfer factor: DTF = Difference of the dry matter activity concentration (Bq.kg-1) of plant grown in open field and plants grown in tent shelter, divided by the atmospheric deposition during the vegetation period (Bq.m-2). The deposition transfer factor for 210Pb thus estimated is in the order of 0.5-1.0 (m2.kg-1 dry matter) for leafy plants like grass and 0.1-0.5 for less leafy plant and straw. For various grains it is < 0.2 and for root fruits it is < 0.003 (m2.kg-1 dry matter). Corresponding values for 210Po are about a factor 3 times higher. The world average activity concentration of 210Po in fresh leafy vegetable is estimated to 320±190 mBq.kg-1, and in cereals and grain products 240±80 mBq.kg-1. The average activity concentration in milk products is 59 ± 13 mBq.kg-1 and in meat products about 70 ± 39 mBq.kg-1. The dietary intake of milk and meat products is 170 kg.a- which is the highest of all food items of terrestrial origin. The

  17. Tracking legacy radionuclides in St. Louis, Missouri, via unsupported (210)Pb.

    Kaltofen, Marco P J; Alvarez, Robert; Hixson, Lucas

    2016-03-01

    Analysis of 287 soil, sediment and house dust samples collected in a 200 km(2)-zone in northern St. Louis County, Missouri, establish that offsite migration of radiological contaminants from Manhattan Project-era uranium processing wastes has occurred in this populated area. Specifically, 48% of samples (111 of a subset of 229 soils and sediments tested) had (210)Pb concentrations above the risk-based soil cleanup limits for residential farming established by the US Department of Energy at the Fernald, OH, uranium plant, which handled and stored the same concentrated Manhattan Project-era wastes; the geographical distribution of the exceedances are consistent with water and radon gas releases from a landfill and related sites used to store and dispose of legacy uranium wastes; and offsite soil and house dust samples proximal to the landfill showed distinctive secular disequilibrium among uranium and its progeny indicative of uranium ore processing wastes. The secular disequilibrium of uranium progeny in the environment provides an important method for distinguishing natural uranium from industrial uranium wastes. In this study, the detection of unsupported (210)Pb beyond expected atmospheric deposition rates is examined as a possible indicator of excessive radon emissions from buried uranium and radium-containing wastes. PMID:26741397

  18. 210Pb method for estimating the rate of carbonate sand sedimentation

    Holmes, Charles W.

    1981-01-01

    The plot of 210Pb activity against depth in carbonate sands on the Virgin Island Bank is a negative asymmetric hyperbolic curve. As depth increases, an initial rapid decrease in 210Pb activity caused by the decay of unsupported 210Pb and 226Ra is followed by increasing activity as a result of 210Pb achieving equilibrium with in growing 230Th. As this curve is time dependent, an estimate of the relative ages in carbonate sequences and the rates of net carbonate accumulation can be made. The ease of 210Pb activity determinations makes this procedure an attractive method in obtaining carbonate sand accumulation rates.

  19. Deposition of atmospheric 210Pb and total beta activity in Finland

    The seasonal and regional variation of the atmospheric 210Pb deposition in Finland was studied. The 210Pb activity concentration in precipitation shows a decreasing trend from southeastern Finland north-westwards. An average deposition of 40 Bq/m2 during a 12 months period was observed. The deposition of 210Pb shows a seasonal variation with minimum in spring and maximum in autumn and winter. The specific activity of 210Pb (activity of 210Pb per unit mass of stable lead) in the atmosphere has returned to the level prior to World War II owing to the reduced lead emissions into the atmosphere. (author)

  20. A record of atmospheric 210Pb accumulation in the industrial city

    Buraeva, E A; Stasov, V V; Zorina, L V; Shramenko, B I

    2013-01-01

    The deposition flux of total atmospheric 210Pb in the industrial city Rostov-on-Don, Russia from 2002 to 2010 has been measured. The variations in annual 210Pb deposition flux appear to be mainly correlated with the number of rains and significant amount of anthropogenic 210Pb, polluted into the surface layer of air in the home-heating period. The average 210Pb deposition is 1.75 mBq/m3. Several meteorological parameters which are strongly associated with the fluctuations of concentrations of 210Pb are identified. These results are useful to provide typical information on the atmosphere radioactivity in an industrial city.

  1. 210Pb dating of sediments from Havana Bay

    The study of sedimentation rates and age of marine sediments has been performed through many years using natural and artificial radioactive isotopes. Polluted sediments were collected in three sampling points in the Havana Bay. Sedimentation rates were estimated using two different radiometric approaches: the depth profiles of 137Cs and 210Pb. The maximum activity 137Cs might indicate the proximity of the 1964's. The unsupported 210Pb has been measured to apply both the Constant Initial Concentration Method (CIC) and the Constant Rate of Supply Method (CRS) Dating Models. The results show values for sedimentation rate ranging from 0.2 up to 1.3 cm x y-1 increasing with time which manifests the importance of the achievement of a project of dredging. (author)

  2. Sedimentation rates in Manila Bay from 210Pb profiles

    Manila Bay is one of the water systems affected by red tide occurrences. In an effort to provide an age control to the cyst produced by the red tide causative organism, Pyrodinium bahamense var compressum, several cores were collected from the bay and analyzed for lead-210 (210Pb) by alpha spectrometry. The surface activity ranges from 1.31 dpm/g to 4.56 dpm/g with an average at 3.32 dpm/g. The derived 210Pb vertical profiles indicate a marked increase of 5x to 10x in sedimentation rate in the last ten years in the deeper portions of the bay. This is probably due to the elevated sediment yield of rivers after the eruption of Mt. Pinatubo in 1991 as can be seen in the profiles of the three cores. (Author)

  3. Determination of 210Pb and 210Po in cigarette tobacco

    Cigarette smoking is one of the important pathways that could contribute to enhance the radiation dose to man, due to the relatively large concentrations of 210Pb and 210Po found in tobacco leaves. In this work, concentrations of these two radionuclides were determined in eight of the most commercialized cigarette brands produced in Brazil. The samples analyzed were bought randomly in the market. The 210Pb was determined by counting the beta activity of the 210Bi in a gas flow proportional detector, after radiochemical separation and precipitation of the PbCr04. The 210Po was determined by alpha spectrometry, using a surface barrier detector, after radiochemical separation and spontaneous deposition of Po in copper disk. The results showed concentrations ranging from 11,9 to 30,2 mBq per gram of dry tobacco for 210Pb and from 10,9 to 27,4 mBq per gram of dry tobacco for 210Po. (author)

  4. Evaluation of 239+240Pu, 137Cs and natural 210Pb fallout in agricultural upland fields in Rokkasho, Japan

    The background distributions of 239+240Pu and 137Cs fallout in agricultural soil were investigated in Rokkasho where Japan's first commercial nuclear fuel reprocessing plant is now being constructed. The mean inventories of 239+240Pu and 137Cs in three fields with non-yam-cultivation history were 116 Bq x m-2 and 3.4 kBq x m-2, respectively. The mean atomic ratio of 240Pu/239Pu for all studied fields was 0.18±0.04, and was similar to that of global fallout. The 239+240Pu concentrations correlated very well with 137Cs (r = 0.97) in spite of heavy disturbance of the soil, and the activity ratio of 239+240Pu/137Cs was 0.037 ± 0.007, which is a typical value for global fallout. These results showed that the nuclides had similar behavior in agricultural upland fields in Rokkasho. Since 210Pb is steadily deposited from the atmosphere to the land, this nuclide could be an index for the degree of disturbance of a field and of soil lost from the field. The ratio of excess 210Pb inventory in the soil to the equivalent inventory of atmospheric 210Pb deposition was 96%, and indicated that soil was not lost from the cultivated fields. (author)

  5. Assessment of 210Pb concentration in Nicotiana tabacum L., burley variety, cultivated in Brazil

    Tobacco products are extensively used throughout the world and the most consumed are cigarettes, cigars and narghile. The damaging effects that these products cause to human health are discussed worldwide and many researches are performed with the aim of relating the use of these products with various diseases. Brazil is the largest exporter and second largest producer of tobacco worldwide, according to the crop year 2009/2010 production. The tobacco plant (Nicotiana tabacum L.) is used to manufacture all derivatives and the chemical composition of the resulting tobacco varies with the type of tobacco leaves, how they are grown, the region where they are cultivated, the characteristics of preparation and the temperature variations resulting from the tobacco incomplete combustion. There is lack of information about the chemical and radiological characterization of the tobacco plant both in international and Brazilian literature. Thus a project was established with the objectives of characterizing chemically and radiologically the three varieties most cultivated in Brazil of Nicotiana tobacum L., Virginia, Burley and Common; this paper presents the preliminary results of 210Pb concentrations for the Burley variety. Plants from this variety were cultivated in pots with organic substrate and fertilizer and in a small farm in natural conditions. The entire plant was analyzed, the organic substrates, the fertilizers and the soil. The results obtained presented higher values for 210Pb in leaves when compared with the other parts of the plant. Comparing the three study areas the highest results of 210Pb concentration were obtained in the plants cultivated in the urban area probably due to its atmospheric deposition. (author)

  6. Assessment of {sup 210}Pb concentration in Nicotiana tabacum L., burley variety, cultivated in Brazil

    Rocha, Rique J.F.X.; Silva, Carolina F.; Frujuele, Jonatan V.; Bovolini, Raquel R.; Damatto, Sandra R., E-mail: rjrocha@ipen.br, E-mail: cfsilva@ipen.br, E-mail: jonatanfrujuele@hotmail.com, E-mail: ra_bovolini@yahoo.com.br, E-mail: damatto@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Lab. de Radiometria Ambiental

    2013-07-01

    Tobacco products are extensively used throughout the world and the most consumed are cigarettes, cigars and narghile. The damaging effects that these products cause to human health are discussed worldwide and many researches are performed with the aim of relating the use of these products with various diseases. Brazil is the largest exporter and second largest producer of tobacco worldwide, according to the crop year 2009/2010 production. The tobacco plant (Nicotiana tabacum L.) is used to manufacture all derivatives and the chemical composition of the resulting tobacco varies with the type of tobacco leaves, how they are grown, the region where they are cultivated, the characteristics of preparation and the temperature variations resulting from the tobacco incomplete combustion. There is lack of information about the chemical and radiological characterization of the tobacco plant both in international and Brazilian literature. Thus a project was established with the objectives of characterizing chemically and radiologically the three varieties most cultivated in Brazil of Nicotiana tobacum L., Virginia, Burley and Common; this paper presents the preliminary results of {sup 210}Pb concentrations for the Burley variety. Plants from this variety were cultivated in pots with organic substrate and fertilizer and in a small farm in natural conditions. The entire plant was analyzed, the organic substrates, the fertilizers and the soil. The results obtained presented higher values for {sup 210}Pb in leaves when compared with the other parts of the plant. Comparing the three study areas the highest results of {sup 210}Pb concentration were obtained in the plants cultivated in the urban area probably due to its atmospheric deposition. (author)

  7. The Use of Biomonitors to Monitor Atmospheric Deposition of 210Pb

    The main source of 210Pb in the environment is the exhalation of 222Rn gas from the ground to the atmosphere during the radioactive decay of natural uranium - radium chain. In the atmosphere this radionuclide is rapidly attached to small particles - aerosols, predominantly on those particles below 0.3 mm. The half-life of 210Pb is longer than the atmospheric residence time of the aerosols on which it resides (1). By sedimentation and washout of aerosols this nuclide is then transferred to the soil or vegetation. The other main sources include burning of fossil fuels and phosphate fertilizers. The usual way to determine the levels of 210Pb and other radionuclides in the atmosphere is the use of a high volume filter system, which should operate for a long time to collect enough material for analysis. An other approach to determining the outdoor levels of radionuclides is the use of suitable biomonitors such as lichens or mosses. These organisms, although neither evolutionarie nor taxonomically related, have some common characteristics which enable them to be used as monitors for atmospheric pollution. They lack roots and protective organs against the substances derived from the atmosphere (stomata and cuticle) and are very efficient accumulators of atmospheric particulate material and chemical substances such as radionuclides or heavy metals (2). The levels of these substances in lichens and mosses are usually much higher than in air particulates or precipitation and for these reason the analysis is much easier. Another advantage of biomonitors over conventional sampling of air particulates or precipitation is that the collection of lichens or mosses is very cheap therefore allows a very large number of sites to be included in the same survey and permits detailed geographical deposition patterns to be drawn (3). It must be emphasised that concentration data on elements or radionuclides in lichens or mosses represent the relative deposition patterns over a certain

  8. A method for rapid determination of 210Pb radioactivity in environmental water

    Background: There are three methods for determination of 210Pb radioactivity concentration in environmental water. One is detecting p rays of 210Bi guided by the EJT 859-1994, one is detecting α rays of 210Po for 210Pb radioactivity, and the other is using gamma ray spectrometer to determinate the radioactivity of 210Pb. But the first method can not give an exact recovery rate of 210Pb, the second one is a time-consuming process, and the third one is unable to detect 210Pb in water samples because of its detection limit. This paper describes a method of rapid determination of 210Pb in environmental water with the anion exchange. Purpose: To determine the radioactivity of 210Pb in water samples rapidly. Methods: The stable Pb carrier is added to the water samples for the recovery rate in the chemical and physical process. 210Pb and Pb carrier in the water samples are adsorbed and concentrated by Fe(OH)3 co-precipitation undergoing heating. 210Pb and its carrier are isolated from most interference by an anion exchange. The PbSO4 precipitation has been purified via being precipitated for three times. The PbSO4 precipitation has been stored in the environmental temperature for one month. And then, the p rays of 210Bi and the daughter of 210Pb are detected to determine the radioactivity concentration of 210Pb. Results: This method provides a stable and reliable result and costs less time than the method that detects α rays of 210Po for 210Pb radioactivity. Conclusions: The method for rapid determination of 210Pb is a practical and reliable method and used to analyze water samples in Yunnan province. (authors)

  9. Sedimentation and lateral transport of 210Pb over the East China Sea Shelf

    210Pb is an effective tracer of constraining particle transport and sedimentation in shelf regions. To reveal the spatial pattern of 210Pb over the East China Sea (i.e. ECS) Shelf, 210Pb in the surface sediments were examined at 11 stations, as well as 234Th and 210Pb in the water column at four stations. Overall, the plume zone of the Yangtze River along the coastline is a source area of 210Pb for the outer shelf, exporting 0.46 dpm cm-2 year-1 at least, which accounts for about 25 % of 210Pb input into this region. In the southern ECS Shelf to the north of the Taiwan Strait, the focusing factor (f) values are higher than unity, indicating a sink area of 210Pb. Boundary scavenging of 210Pb contributes 0.36 dpm cm-2 year-1 to this sink area on the basis of a mass balance model evaluation. Lateral transport of 210Pb to this region, quantified by 234Th and 210Pb in the water column, varied from 3.34 to 6.39 dpm cm-2 year-1 with an average of 4.83 dpm cm-2 year-1, also supporting its sink characteristic. To the southwest of the Cheju Island, the f values were less than unity, revealing a source region of 210Pb. The average export flux of 210Pb from this region was 1.64 dpm cm-2 year-1. Therefore, 210Pb sedimentation/settling showed significantly heterogeneous sedimentation of particulate matter over the ECS Shelf. (author)

  10. The Radiological Impact of 210Pb and 210Po Released from the Iron- and Steel-Making Plant ILVA in Taranto (Italy on the Environment and the Public

    Guogang Jia

    2013-01-01

    Full Text Available Lead-210 and 210Po are naturally occurring radionuclides. Due to volatile characteristic of lead and polonium, environmental pollution of 210Pb and 210Po released from the coal power plant, steel-making industry and refractory material industry has been an exposure problem for the members of public. In this paper studies on the activity concentrations of 210Po and 210Pb in the raw materials, dust particles, surficial soils and atmospheric particulate samples collected in the area of the Iron- and Steel-Making Plant ILVA Taranto (Italy were made. These data have been used to evaluate the source-term, distributions, inventories, mass balance, biological availability, ecological migration processes and public exposure risk of 210Pb and 210Po in the concerned environment.

  11. 137Cs and 210Pb distribution in Manila Bay sediment

    Two radionuclides were measured in surface sediment samples taken from geographically distributed sections of Manila Bay, namely cesium-137 (137Cs) and lead-210 (210Pb). Results indicated a noticeable change in the radioactivity concentration levels in sediments collected in 2005 and 2010, with a median concentration of 1.0 and 2.64 Bq kg-1, respectively. Higher levels of 137Cs radioactivity were measured in the northern and inner portion of the bay adjacent to major river systems, agricultural and highly industrialized urban areas. 137Cs isotope increased in activity in most of the samples especially in the northwestern areas of Bataan and Pampanga with five times more than the activity from the first sampling measurements. Nevertheless, radioactivity concentrations observed in surface sediments along the bay are within the range of radioactivity in several areas monitored in the Northern Hemisphere. The country has been frequented by tropical cyclones and storms that have caused erosion, which may have introduced elevated material input in the bay. In addition, wind-driven circulation especially in the shallower areas of the bay is a possibility for the substantial sediment movement and accumulation along this coast. Conversely, areas with higher 137Cs have lower values of 210Pb. In an undisturbed environment, 210Pb deposition values are assumed nearly constant. Hence, changes in the radioactivity concentration levels of these radionuclides can be an indicator of pollution input from land-based sources, sediment movement and reworking in the coastal areas. At present, there is very limited information on the radioactivity level of various radioisotopes in Manila Bay.The data obtained are benchmark values against which changes that will be occurring in the bay can be assessed. (author)

  12. Geochemical fractionation of 210Pb in oxic estuarine sediments of Coatzacoalcos River, Gulf of Mexico

    210Pb activities were analyzed in surface sediments from the Coatzacoalcos River (Gulf of Mexico) to evaluate its distribution according to sediment grain size and in different geochemical compartments by using sequential extraction techniques. The geochemical fractionation experiments provided compatible results: by using the Tessier's method more than 90% of the 210Pb activity in the samples was found the residual fraction (primary and secondary minerals) and the remaining (210Pb content was found in comparative amounts in the reactive, the silicate, and the pyrite fractions (accounting together for >80%), and the rest was found in the residual fraction. The grain size fractionation analyses showed that the 210Pb activities were mostly retained in the clay fraction, accounting up to 60-70% of the 210Pb total activity in the sediment sample and therefore, it is concluded that the separation of the clay fraction can be useful to improve the analysis of low 210Pb content sediments for dating purposes. (author)

  13. Bioavailability of radionuclides 226Ra, 228Ra and 210Pb present in the brazilian phosphate fertilizers and phosphogypsum

    Phosphogypsum, also called gypsum, by-product of the phosphate fertilizer industry, can be used as soil conditioner since it provides improvements in the soil-plant system. However, this by-product concentrates radionuclides of the U and Th series, present in the phosphate rock used as raw material, which can impact the environment. In order to study the bioavailability of radionuclides, samples of phosphogypsum and phosphate fertilizers (monoammonium phosphate and triple superphosphate) were analyzed. The concentration of 226Ra, 228Ra and 210Pb were determined by gamma spectrometry. The samples were leached with a mild EDTA solution and the radionuclides present in the final solution were determined by total alpha and beta counting on a gas flow proportional counter. The percentage of extraction varied from 1.6% to 1.7% for 210Pb, from 0.5% to 1.4% for 226Ra and from 0.1% to 1.0% for the 228Ra in phosphogypsum samples. The low percentage of extraction obtained for the radionuclides can be partly explained by the low solubility of phosphogypsum, which ranged from 7.7% to 16%. For the monoammonium phosphate samples the percentage of extraction were less than 26% for 226Ra, less than 10% for '228Ra and less than 10% for 210Pb. In spite of the high solubility of 77% of monoammonium phosphate in the EDTA solution, low concentrations of radionuclides were observed in the leached solution. For the triple superphosphate samples, the percentage of extraction was 2.3% for 226Ra, 1.2% for 228Ra and 11.3% for 210Pb. In spite of the high solubility of 66% of triple superphosphate in the EDTA solution, low concentrations of radionuclides were observed in the leached solution. (author)

  14. Lead Precipitation Fluxes at Tropical Oceanic Sites Determined From ^(210)Pb Measurements

    Settle, D. M.; Patterson, C C; Turekian, K K; Cochran, J. K.

    1982-01-01

    Concentrations of lead, ^(210)Pb, and ^(210)Po were measured in rain selected for least influence by local sources of contamination at several tropical and subtropical islands (Enewetak; Pigeon Key, Florida; and American Samoa) and shipboard stations (near Bermuda and Tahiti). Ratios expressed as ng Pb/dpm ^(210)Pb in rain were 250–900 for Pigeon Key (assuming 12% adsorption for ^(210)Pb and no adsorption for lead), depending on whether the air masses containing the analyzed rain came from th...

  15. Relationship Between 210Pb Concentrations in Solid Wastes and Plants from Uranium Mill Tailings

    Full text: The exploitation and treatment of uranium ore at the Urgeirica mine (north of Portugal) have led to the accumulation of large amounts of soild wastes (mill tailings) in dams (tailing ponds). These solid wastes containing natural radionuclides could be dispersed by the action of atmospheric agents and contaminate the environment. To minimize the dispersion of these radionuclides into the environment the dams were revegetated with pines (Pinus pinea) and eucalyptes (Eucalyptus globolus). The objective of this study is to know the 210Pb behaviour in what concerns its transfer from the uranium mill tailings to these plants, through the analysis of relationships between 210Pb concentrations in the solid wastes and the plants. Solid wastes and plant samples were randomly collected at the dams and the 210Pb activity concentration in solid wastes and plant (aerial part and roots) samples were determined by gamma spectrometry. The results obtained for pines show a good correlation between 210Pb concentrations in the solid wastes and roots. No correlation was found to 210Pb concentrations in the solid wastes and needles. The 210Pb concentration data for eucalyptes show a quite good correlation between 210Pb concentrations in the solid wastes and leaves. Concentration ratio data, solid wastes/roots and solid wastes/needles for pines are on the same order of magnitude. The 210Pb uptake by pines (roots and needles) and eucalyptes (leaves) show that 210Pb concentration ratios decrease at low 210Pb concentrations in the solid wastes and appear relatively constant at higher 210Pb concentrations in the solid wastes. Data presented for 210Pb in this paper, will be compared with those obtained for 226Ra on the same samples. (author)

  16. Recent aquatic ecosystem response to environmental events revealed from 210Pb sediment profiles

    The 210Pb dating method was first introduced by , and since then has been applied to study sediment from lakes, estuaries and coastal marine environments. Hundreds of studies around the world have used 210Pb as a geochronological tool in aquatic ecosystems. However little attention has been paid to the potential of this naturally occurring isotope as an environmental tracer of ecological events. Here we report three instances in which 210Pb profiles measured on undisturbed sediment cores from lakes, rivers and fjords show us the potential of 210Pb profile as a tracer of natural and anthropogenic processes. The methodology used here is a suite of techniques combining biogeochemistry (micro-electrodes), paleomagnetism (susceptibility), sediment characteristics (LOI) and visualization (SPI and X-ray) applied to the interpretation of 210Pb profiles. We measured 210Pb profiles on sediments from a river, Cruces River (Chile), which recorded a clear shift in the water chemistry caused by a pulp mill effluent to the river. Here metal mobilization and remobilization of the tracer may be the cause of the observed profile. We also measured 210Pb profiles in sediment from two fjords of Southern Chile (Pillan and Renihue), the sudden deposition change of fresh 210Pb with depth observed could very well be the result of bioturbation but it occurred in a seafloor area deprived of bioturbators. In this case, 210Pb recorded the onset of aquaculture activities (fish farming) that took place two decades ago. Finally, 210Pb profiles measured in two lakes in the 'pampa Argentina': Epecuen and Venado showed a particular shape with depth. These profiles apparently registered a sudden depositional event with recent 210Pb material, probably related to strong shifts in precipitation and drought cycles in that part of the world. These three examples show that 210Pb profiles provide valuable information not only on geochronology, but also related to natural and anthropogenic short term

  17. Behaviors of 210Pb and 210Po around hydrothermal vents in the Okinawa Trough

    杨永亮; 日下部正志; 山本惠幸

    2002-01-01

    Vertical profiles for the uranium-series radioisotopes 210Pb and 210Po were obtained at the two hydrothermal vent sites, the Iheya Ridge and the Minami-Ensei Knoll, in the Mid-Okinawa Trough in 1993 and 1994, respectively. In 1995, both radioisotopes were measured at the Minami-Ensei Knoll again. At the Iheya Ridge, where the hydrothermal activity is not active as reflected by the CH4 and 222Rn data, both the total 210Pb and 210Po activities show deficiency relative to their parents, and the mean residence time of 210Pb and 210Po is approximately equal to 20 and 2~ 5 a, respectively. At the Minami-Ensei Knoll, which is characterized by black smokers, the total 210Pb(0.167 × 10-3 ~2.5 × 10-3 Bq/kg) around the plumes is deficient relative to 226Ra but the total 210Po activities ( 1.83 × 10- 3 ~ 2.83× 10-3 Bq/kg) are in excess relative to 210Pb. The 210Po activities are higher than those in the East China Sea and the Okinawa Trough and excess 210Po has been found. The 210Pb/226Ra and 210Po/210Pb activity ratios are 0.1~ 0.4 and 1.1 ~ 7.8, respectively. 210Pb is preferentially scavenged in the hydrothermal plumes. The possible mechanisms governing the concentration of 210Pb in the Minami-Ensei Knoll involve a lateral transport of 210Pb via diffusion. The high 210Po/210Pb activity ratios in the hydrothermal plumes suggest a depletion of 210Pb and addition of 210Po in the hydrothermal vent area.

  18. Estimation of sediment loading in Asian coastal area using 210Pb inventory in mangrove sediment

    Full text: Concentrations of 210Pb in coastal sediment are generally controlled by local atmospheric 210Pb flux and fine sediment input to coastal area, because the 210Pb has high affinity to inorganic fine particles and 210Pb inventory in coastal sediment is coincided with sediment loading to the area. Thus the 210Pb level in coastal sediment is good index of sediment loading to coastal zones. However, in subtropical/tropical coastal area, such as S-E Asian coast, sediment loading is widely variable due to seasonal difference of precipitation and coastal sediment discharge among rainy/dry season. Secondly, the S-E Asian coastal areas are mostly covered with mangroves those entrap the sediment particle supplied from river to adjacent coastal waters. Since the entrapped fine sediment particles include not only the excess 210Pb supplied from local atmosphere but also the accumulated sediment particles by terrestrial input, thus the 210Pb inventory exceeds largely compared to the atmospheric supply. Thus the 210Pb inventory balance in mangrove area is expected to reflect drastically the local sediment loading conditions in S-E Asia. We studied the 210Pb balance in subtropical mangrove coastal water in Japan and found that the 210Pb was useful natural tracer to evaluate the coastal sediment load. However, limited data are reported about the mangrove coastal area. In this study, we collected mangrove sediment cores at the Japan and Viet Nam and analyzed the 210Pb concentrations in sections of different depth and location. By comparing with the atmospheric flux, we estimate the balance of the 210Pb in the area and evaluate the sediment loading to the studied mangrove area. (author)

  19. Radiolead (210)Pb and (210)Po/(210)Pb activity ratios in calcium supplements and the assessment of their possible dose to consumers.

    Strumińska-Parulska, Dagmara I

    2016-08-23

    This paper presents the results of pioneer study of the most popular calcium supplements as a potential additional source of radiolead (210)Pb in human diet. The analyzed calcium pharmaceutics contained organic or inorganic calcium compounds; some came from natural sources as mussels' shells, fish extracts, or sedimentary rocks. The idea was to investigate the naturally occurring (210)Pb activity in different calcium supplements and calculate the annual effective radiation dose from radiolead (210)Pb decay in consumed calcium supplement. The results showed (210)Pb concentrations in natural origin calcium supplements (especially sedimentary rocks) were significantly higher. The highest (210)Pb activity concentrations were determined in mineral tablets made from dolomite - 2.97 ± 0.18 mBq g(-1), while the lowest was observed in organic calcium compounds - both calcium lactate - 0.08 ± 0.01 and 0.13 ± 0.01 mBq g(-1). The highest annual radiation dose from (210)Pb taken with 1 tablet of calcium supplement per day was calculated for soluble calcium lactate sample - 1.19 ± 0.03 µSv year(-1), while the highest annual radiation dose from (210)Pb taken daily with 1 g of pure Ca for dolomite - 5.57 ± 0.34 µSv year(-1). PMID:27253716

  20. 210Pb and 210Po activities in French foodstuffs

    The data on 210Pb and 210Po activities in French foodstuffs acquired during the last 15 years are numerous enough to derive reference values which will be usable to assess the dose to the French population due to the intake of these two natural radionuclides. The means and ranges are close to those observed in various countries and are most often higher than the reference values proposed by UNSCEAR. Mussels and oysters exhibit the highest 210Po activities of all kinds of foodstuffs, with a mean value of 27 Bq.kg-1 fresh weight, followed by crustaceans and small fish species (anchovies, mullets, sardines, etc.) with 210Po activities in the order of 3 to 10 Bq.k-1 fresh weight; cephalopods and other fish species presenting activities around 1 to 3 Bq.kg-1 fresh, close to the UNSCEAR reference value. Below these highest 210Po activities are those of 210Po and 210Pb in terrestrial kinds of foodstuffs, by decreasing order: meats (around 1 Bq.kg-1 fresh), cereals (0.4 Bq.kg-1), leafy vegetables (0.3 Bq.kg-1), other vegetables and fruits (0.1 Bq.kg-1), and milk (from 0.03 to 0.1 Bq.L-1). (authors)

  1. Biogeochemistry of (210)Pb and (210)Po in fresh waters and sediments. Doctoral thesis

    The geochemical cycling of (210)Pb in a Massachusetts lake was studied. A mass balance for the epilimnion showed that (210)Pb inputs by precipitation were matched by outputs on settling particles, so direct uptake by bottom sediments was inconsequential. Below the epilimnion, vertical mixing was very low because of a steep temperature/density gradient, and this limited vertical transport. Anoxic conditions caused remobilization of iron and (210)Pb, which reprecipitated at the oxycline and returned to the bottom via settling. Below the zone of precipitation, (210)Pb and iron distributions resulted from constant release from anoxic sediments and dilution in the water column. Sediment (210)Pb distributions were caused by sedimentation and Fickian transport. The Fickian component was equal to the pore water diffusive flux. In pore waters, (210)Pb and (210)Po were 100 times greater that in overlying water and had steep concentration gradients, unlike Fe, Mn, S(-II), and alkalinity. (210)Pb partition coefficients decreased from 15000 to 1500 with depth controlled by sorption on iron oxides. Remobilization to the water column comes from a thin layer of iron-rich floc near the sediment/water interface. Deeper in the cores, diffusive transport can cause redistribution of (210)Pb to an extent that can affect (210)Pb dating

  2. Concentrations of 226Ra and 210Pb in agricultural products surrounding the first brazilian mine and mill in Pocos de Caldas, MG

    As a complement to the pre-operational environmental monitoring program of the Brazilian first uranium mine and mill, a survey of 226Ra and 210Pb in agriculture products, and in the corresponding soils, were carried out in the Pocos de Caldas Plateau. The survey intended to determine site specific transfer factors, in order to better estimate radiation doses on the population. Resulting from the plant operation. In local soils, 226Ra and 210Pb have similar concentrations. The average contents are comparable to the values found in areas of normal radioactivity, but the maximum values are higher by one order of magnitude. In the vegetables analyzed (beans, carrot, corn and potato), 226Ra concentrations are slightly higher than those of 210Pb, and the maximum values are also one order of magnitude greater than in normal regions. For both radionuclides, the average soil-to-plant transfer factors are of the order of 10-3 and 10-2, when related to total and to exchangeable contents in soils, respectively. These results led to the conclusion that 226Ra and 210Pb have similar importance, concerning the population exposure via the foodstuff ingestion pathway. Therefore, it was recommended to carry on routine monitoring program for both radionuclides in the main agriculture crops. However, the naturally elevated radionuclide concentrations, in some local vegetables, will decrease the sensitivity for detecting small increments resulting from the plant operation. (author)

  3. Spatial and depth variation of 210Po and 210Pb in monazite sand along HBRA of coastal Kerala

    The samples collected from high background radiation area were analyzed for 210Po and 210Pb activities in order to understand their distribution, enrichment and depth profile in the beach sand. The 210Po and 210Pb activities vary from 1.85 to 31.27 Bq kg-1 and 9.77 to 132.30 Bq kg-1 respectively. The 210Po/210Pb indicate that the radionuclides 210Po and 210Pb are not in equilibrium and the accumulation of 210Pb in sand is greater than for 210Po. The spatial variations of 210Po and 210Pb activities were studied in detail. (author)

  4. 210Po and 210Pb activity concentration in the coral bands of Pulau Tuba, Langkawi

    We examined the concentrations of 210Po and 210Pb in each layers of coral banding of coral skeletons. Concentrations of 210Po and 210Pb in massive corals (i.e. Porites, Favites, Platygyra and Goniostrea) from Pulau Tuba, Langkawi were measured using the Alpha-Spectrometry. The concentrations of 210Po were higher than the concentrations of 210Pb. This may due to continuing source of 210Po from 210Pb. Highest concentration on 210Po in coral banding was 48.30 ± 28.53 Bq/ kg, meanwhile for 210Pb was 12.86 ± 5.80 Bq/ kg. The ratios of 210Po/ 210Pb were in the range of 2.21 to 5.49. The variation activity concentrations of 210Po and 210Pb in the coral bands are important to consider in using coral as retrospective study of environmental changes. The coral can represent the total of 210Po and 210Pb in the surrounding water for the past few years. (author)

  5. Atmospheric concentrations and deposition fluxes of 7Be and 210Pb at Rokkasho village, Japan

    Biweekly atmospheric concentrations and deposition fluxes of 7Be and 210Pb were measured at Rokkasho, Aomori Prefecture, Japan, from March 2000 to March 2006, to clarify their regional features. The atmospheric concentration of 7Be was low in summer and winter and high in spring and fall, and that of 210Pb was low in summer and high in winter. Negative correlations were between the atmospheric 7Be or 210Pb concentrations and precipitation in the sampling periods, and that suggested that both nuclides were removed from the atmosphere mainly by wet deposition (rain or snow). The deposition fluxes of 7Be and 210Pb were low in summer and high in winter to spring. Deposition fluxes of 7Be and 210Pb positively correlated to precipitation. From the results of the power spectral analysis by fast Fourier transform, annual periodicities of 7Be and 210Pb deposition at Rokkasho could be classified as a double peak distribution pattern and single peak distribution pattern, respectively. Backward trajectories for 72 h were calculated every 6 h in order to clarify the relation of air mass transport course and atmospheric concentrations of 210Pb. The results showed that atmospheric 210Pb concentrations were strongly affected by air mass from the northern Asian continental area above 40degN. (author)

  6. The 210Pb budget of the North Sea. Atmospheric input versus sediment flux

    Atmospheric deposition is one of the main sources of 210Pb in the North Sea water. Annual variations of this flux are large in the Netherlands. Translated to the North Sea area the atmospheric deposition is 42 Bq.m-2.y-1. In the 210Pb budget of the North Sea, supply by rivers, as artificial supply by power plants and fertilizer plants, does not play a great role. Fishery activities is not a good scavenger in the total 210Pb budget. From measurements of 36 box-cores in the North Sea the average 210Pb flux to the sediment is estimated 150 Bq.m-2.y-1. Fluxes to the sediment smaller than 10% of the atmospheric flux, occur in the sandy areas of the Southern Bight and Dogger Bank. Large fluxes, up to 50 times the atmospheric deposition, occur mainly in the fine grained deposition areas of the Skagerrak and the Norwegian Trench. The net lateral flux accounts for 1/3 part of the flux to the sediment: the North Sea is a true sink for 210Pb. The radon flux from the sediment supplies 1/3 of the 210Pb flux to the sediment. Based on the 210Pb budget total mass accumulation in the North Sea is 1100 x 109 kg.y-1, this is an order of magnitude higher than figures obtained from transport of suspended matter and from 210Pb sedimentation rates. (author)

  7. Method for spiking soil samples with organic compounds

    Brinch, Ulla C; Ekelund, Flemming; Jacobsen, Carsten S

    2002-01-01

    We examined the harmful side effects on indigenous soil microorganisms of two organic solvents, acetone and dichloromethane, that are normally used for spiking of soil with polycyclic aromatic hydrocarbons for experimental purposes. The solvents were applied in two contamination protocols to either......,000-fold higher than in control soil, probably due mainly to release of predation from indigenous protozoa. In order to minimize solvent effects on indigenous soil microorganisms when spiking native soil samples with compounds having a low water solubility, we propose a common protocol in which the...

  8. 7Be and 210Pb radioactivity and implications on sources of surface ozone at Mt. Waliguan

    ZHENG Xiangdong; WANG Guojiang; TANG Jie; ZHANG Xiaochun; YANG Wei; H. N. Lee; WANG Changsheng

    2005-01-01

    Beryllium-7 (7Be) and lead-210 (210Pb) radioac- tivity in aerosols collected, from October 2002 to January 2004 at Mt. Waliguan, by the Global Atmospheric Watch (GAW) Station, Qinghai Province is presented. The data were analyzed together with simultaneously measured surface ozone concentrations. We found that short time variations of 7Be and 210Pb were linked to alternations of synoptic weather around the Mt. Waliguan region. 210Pb showed the lowest concentration in summer while 7Be showed no obvious sea- sonal changes. Relatively high 7Be and 210Pb radioactivity was observed at Mt. Waliguan when compared with the ob- servations at other mountain sites in other parts of the world. Surface ozone and 7Be showed a consistent seasonal variation. Surface ozone correlated fairly well with 7Be/210Pb ratio. This suggested that vertical transport from higher altitudes of the atmosphere has predominant effects on the budget of surface ozone at Mt. Waliguan.

  9. An evaluation of the exposure to 210Pb-210Po in italian population

    Following an introduction on the behaviour in the environment and in man of 210Pb-210Po, experimental data are reported on 210Pb-210Po exposure of the italian population. The analytical methods used to measure 210Pb-210Po activity in the many biological and environmental samples analyzed are also reported. The data collected refer to the intake, excretion, internal burden and metabolism both in a group of subjects representative of the general population and in other critical groups exposed to high internal contamination of 210Pb-210Po, as the radioactive spa wopkes and the miners. The absorbed dose due to 210Pb-210Po has also been evaluated, on the basis of data referring to the various population groups

  10. Method for Spiking Soil Samples with Organic Compounds

    Brinch, Ulla C.; Ekelund, Flemming; Jacobsen, Carsten S.

    2002-01-01

    We examined the harmful side effects on indigenous soil microorganisms of two organic solvents, acetone and dichloromethane, that are normally used for spiking of soil with polycyclic aromatic hydrocarbons for experimental purposes. The solvents were applied in two contamination protocols to either the whole soil sample or 25% of the soil volume, which was subsequently mixed with 75% untreated soil. For dichloromethane, we included a third protocol, which involved application to 80% of the so...

  11. Excess unsupported sup(210)Pb in lake sediment from Rocky Mountain lakes

    Sediment cores from four high-altitude (approximately 3200 m) lakes in Rocky Mountain National Park, Colorado, were dated by sup(210)Pb chronology. Background (supported) sup(210)Pb activities for the four cores range from 0.26 to 0.93 Beq/g dry weight, high for typical oligotrophic lakes. Integrated unsupported sup(210)Pb ranges from 0.81 (a typical value for most lakes) to 11.0 Beq/cmsup(2). The sup(210)Pb activity in the surface sediments ranges from 1.48 to 22.2 Beq/g dry weight. Sedimentation from Lake Louise, the most unusual of the four, has 22.2 Beq/g dry weight at the sediment surface, an integrated unsupported sup(210)Pb=11.0 Beq/cmsup(2), and supported sup(210)Pb=0.74 Beq/g dry weight. sup(226)Ra content of the sediment is insufficient to explain either the high unsupported sup(210)Pb or the sup(222)Rn content of the water column of Lake Louise, which averaged 96.2 Beq/L. We concluded that sup(222)Rn-rich groundwater entering the lake is the source of the high sup(222)Rn in the water column. This, in turn, is capable of supporting the unusually high sup(210)Pb flux to the sediment surface. Groundwater with high sup(222)Rn may control the sup(210)Pb budget of lakes where sediment cores have integrated unsupported sup(210)Pb greater than 2 Beq/cmsup(2)

  12. Indoor air as an important source for 210Pb accumulation in man

    A pilot study was performed with measurements in a German, inhabited, two-family house, to obtain data on the correlation between the equilibrium equivalent radon concentration Ceq and the 210Pb concentration CPb in indoor air. Aerosol samples were collected in various rooms of the house under conditions of low ventilation. The data indicate a linear correlation between Ceq and CPb. A regression analysis, assuming such a relationship, resulted in the following equation: CPb (in mBq.m-3)=8.2x10-3 Ceq (in Bq.m-3) + 0.32. From this relationship it follows that in environments with enhanced radon concentrations direct inhalation of 210Pb is an important source for 210Pb accumulation in man. It was estimated that at an indoor 222Rn concentration of 1,000 Bq.m-3, the 210Pb uptake from inhalation amounts 32 mBq.d-1 of which 62% originates from the direct inhalation of 210Pb. Only the remaining third can be attributed to inhaled short-lived radon progeny and to radon gas dissolved in body tissues. It is shown that, in addition to ingestion and even for elevated indoor radon concentrations, direct inhalation of indoor 210Pb is a further important source of uncertainty, when in vivo measurements of the 210Pb activity in the human body are used as a measure of cumulative radon exposure. (author)

  13. Atmospheric deposition patterns of 210Pb and 7Be in Cienfuegos, Cuba

    The radiometric composition of bulk deposition samples, collected monthly for one year, February 2010 until January 2011, at a site located in Cienfuegos (22° 03′ N, 80° 29′ W) (Cuba), are analysed in this paper. Measurement of 7Be and 210Pb activity concentrations were carried out in 12 bulk deposition samples. The atmospheric deposition fluxes of 7Be and 210Pb are in the range of 13.2–132 and 1.24–8.29 Bq m−2, and their mean values are: 56.6 and 3.97 Bq m−2, respectively. The time variations of the different radionuclide have been discussed in relation with meteorological factors and the mean values have been compared to those published in recent literature from other sites located at different latitudes. The annual average flux of 210Pb and 7Be were 47 and 700 Bq m−2 y−1, respectively. Observed seasonal variations of deposition data are explained in terms of different environmental features. The atmospheric deposition fluxes of 7Be and 210Pb were moderately well correlated with precipitation and well correlated with one another. The 210Pb/7Be ratios in the monthly depositions samples varied in the range of 0.05–0.10 and showed a strong correlation with the number of rainy days. - Highlights: • We evaluated for first time in Cuba the atmospheric deposition fluxes of 7Be and 210Pb. • The annual average flux of 210Pb and 7Be were 47 and 700 Bq m−2 y−1, respectively. • The atmospheric deposition fluxes of 7Be and 210Pb are correlated with precipitation. • 7Be and 210Pb present similar removal behaviour from the atmosphere

  14. Research to improvement of the definition of 210 Po and 210 Pb in deposition

    Investigation to the improvement of the determination of 210Po and 210Pb in deposition. The results of the determination of 210Po and 210Pb in deposition in 1995 do not meet the criteria specified. The chemical recovery of the 208Po tracer added is by many analyses less than the required 50%. The cause of the poor chemical recovery is investigated. This report describes the execution of the investigation and the results. The investigation has led to the improvement of the determination of 210Po and 210Pb in deposition. 12 refs

  15. Sedimentation rates in Kagoshima Bay, Southwestern Japan, using the 210Pb method

    Yokota K; Inoue M.; Kofuji H.; Maeda H.

    2012-01-01

    To understand the pattern of sedimentation rates as fundamental physical parameter of coastal environment, the 210Pb dating method was applied to core samples collected from Kagoshima Bay, Southwestern Japan. The sedimentation rate varied at each location within the bay (0.08–0.30 g·cm−2·y−1), and the rate at the bay-head area was less than that at the centre of the bay. The inventory of ex210Pb has a lower value in the bay-head area. The low ex210Pb inventory at Stn.5' is considered to be du...

  16. Recent aquatic ecosystem response to environmental events revealed from 210Pb sediment profiles.

    Mulsow, S; Piovano, E; Cordoba, F

    2009-01-01

    The (210)Pb dating method was first introduced by Goldberg (1963), and since then has been applied to study sediment from lakes, estuaries and coastal marine environments. Hundreds of studies around the world have used (210)Pb as a geochronological tool in aquatic ecosystems. However little attention has been paid to the potential of this naturally occurring isotope as an environmental tracer of ecological events. Here we report three instances in which (210)Pb profiles measured on undisturbed sediment cores from lakes, rivers and fjords show us the potential of (210)Pb profile as a tracer of natural and anthropogenic processes. The methodology used here is a suite of techniques combining biogeochemistry (micro-electrodes), paleomagnetism (susceptibility), sediment characteristics (LOI) and visualization (SPI and X-ray) applied to the interpretation of (210)Pb profiles. We measured (210)Pb profiles on sediments from a river, Cruces River (Chile), which recorded a clear shift in the water chemistry caused by a pulp mill effluent to the river. Here metal mobilization and remobilization of the tracer may be the cause of the observed profile. We also measured (210)Pb profiles in sediment from two fjords of Southern Chile (Pillan and Reñihue), the sudden deposition change of fresh (210)Pb with depth observed could very well be the result of bioturbation but it occurred in a seafloor area deprived of bioturbators. In this case, (210)Pb recorded the onset of aquaculture activities (fish farming) that took place two decades ago. Finally, (210)Pb profiles measured in two lakes in the "pampa Argentina": Epecuen and Venado showed a particular shape with depth. These profiles apparently registered a sudden depositional event with recent (210)Pb material, probably related to strong shifts in precipitation and drought cycles in that part of the world. These three examples show that (210)Pb profiles provide valuable information not only on geochronology, but also related to

  17. Fallout 210Pb as tools for studying distribution and transport of man-made long-lived radionuclides in terrestrial environment

    The distribution and transport processes of anthropogenic long-lived radionuclides such as 137Cs and 239,249Pu in soil are quite variable even in small areas and influenced by the soil properties, speciation, meteorological conditions, etc. As an attempt to evaluate these differences from place to place, fallout 210Pb in soil from the some areas in Japan was measured together with 139Cs and 239,240Pu. The results indicated that the evaluation of fallout 210Pb inventory and residence time might be useful as an index in quantitatively comparing the spatial distribution, contamination level and migration behavior of different radionuclides such as 139Cs and 239,240Pu in different areas. (author)

  18. Evaluating gully erosion using 137Cs and 210Pb/137Cs ratio in a reservoir catchment

    Water erosion in the hilly areas of west China is the main process contributing to the overall sediment of the Yellow River and the Yangtze River. The impact of gully erosion in total sediment output has been mostly neglected. Our objective was to assess the sediment production and sediment sources at both the hillslope and catchment scales in the Yangjuangou reservoir catchment of the Chinese Loess Plateau, northwest China. Distribution patterns in sediment production caused by water erosion on hills and gully slopes under different land use types were assessed using the fallout 137Cs technique. The total sediment production from the catchment was estimated by using the sediment record in a reservoir. Sediment sources and dominant water erosion processes were determined by comparing 137Cs activities and 210Pb/137Cs ratios in surface soils and sub-surface soils with those of sediment deposits from the reservoir at the outlet of the catchment. Results indicated that landscape location had the most significant impact on sediment production for cultivated hillslopes, followed by the terraced hillslope, and the least for the vegetated hillslope. Sediment production increased in the following order: top>upper>lower>middle for the cultivated hillslope, and top>lower>upper>middle for the terraced hillslope. The mean value of sediment production declined by 49% for the terraced hillslope and by 80% for the vegetated hillslope compared with the cultivated hillslope. Vegetated gully slope reduced the sediment production by 38% compared with the cultivated gully slope. These data demonstrate the effectiveness of terracing and perennial vegetation cover in controlling sediment delivery at a hillslope scale. Averaged 137Cs activities and 210Pb/137Cs ratios in the 0-5 cm surface soil (2.22-4.70 Bq kg-1 and 20.70-22.07, respectively) and in the 5-30 cm subsoil (2.60 Bq kg-1 and 28.57, respectively) on the cultivated hills and gully slopes were close to those of the deposited

  19. Geochronology of lake sediments using 210Pb with double energetic window method by LSC: An application to Lake Van

    In this study the age and sediment accumulation rates of the lake sediment were calculated by using the 210Pb concentrations through the sediment core. The specific activity of 210Pb for each sediment section was determined by LSC with double energetic window method which relies on the direct determination of 210Pb without waiting for the in growth of 210Po from 210Pb. For the successful determination of this radionuclide two counting windows were optimized to eliminate the overlapping of the beta spectra of 210Pb and 210Bi. - Highlights: • LSC method was used to construct the geochronlogy of Lake Van. • Age and accumulation rates of the lake sediment were calculated by using the 210Pb concentrations. • 210Pb activity was determined by LSC with double energetic window method. • The sedimentation rate varies significantly from 0.4 to 0.7 mm yr−1

  20. Study of 7Be and 210Pb as radiotracers of African intrusions in Malaga (Spain)

    The relationship between the particulate matter in the atmosphere of Malaga and the origin of air masses with special attention to African intrusions was analyzed. The concentrations of PM10 and the activities of some radionuclides (7Be and 210Pb) as tracers of these intrusions are discussed. The origin of these radiotracers is completely different. 210Pb is a good tracer of air masses traveling close to the ground and come from inland areas. On the other hand, the production of 7Be is very low in the vicinity of the Earth's surface, and increases with altitude, making it a great tracer of stratospheric air masses in the troposphere. Studies of radionuclide activities in aerosol particles provide a means for evaluating the integrated effects of transport and meteorology on the atmospheric loadings of substances with different sources. Measurements of aerosol mass concentration and specific activities of 7Be and 210Pb in aerosols at Malaga (36° 43′ 40″ N; 4° 28′ 8″ W) for the period 2009–2011 were used to obtain the relationships between radionuclide activities and airflow patterns by comparing the data grouped by air mass trajectory. The average concentration values of 7Be and 210Pb over the 3-year period have been found to be 5.05 and 0.55 mBq m−3, respectively, with mean aerosol mass concentration of 53.6 μg m−3. Taking into account the outbreaks of the daily values limits of PM10 in the study period (2009–2011), the origin of air masses is studied to explain three different situations of both radionuclides 7Be and 210Pb: 1) high concentrations of 7Be and low concentrations of 210Pb; 2) high concentrations of 210Pb and low concentrations of 7Be and 3) high concentrations of 7Be and 210Pb. - Highlights: • Time series of 7Be, 210Pb and PM10 recorded at Malaga (Spain) are analyzed over a 3-y period. • Three different scenarios in the concentrations of 7Be and 210Pb were observed. • High activities of 7Be indicated dust intrusions

  1. Dating hapuka otoliths using 210 Pb/226 Ra, with comments on dating orange roughy otoliths

    It is shown that Hapuka otoliths cannot be reliably dated using the 210 Pb/ 226 Ra method because contrary to previous assumptions, excess 210 Pb is incorporated into the outer layers of otoliths which have been taken from old fish, though the 226 Ra incorporation remains normal. This is shown to apply also to Orange Roughy otoliths. Ages based on calculations using previously published methods will be artificially old. (author). 13 refs., 2 tabs., 3 figs

  2. Validating an erosion model using the environmental radionuclide 210Pb in the Lake Wollumboola catchment, southwestern NSW, Australia

    Soil erosion is a key limitation to achieving sustainable land use and effective soil management, and is the major source of sediment to Australian water bodies resulting in degradation of water quality. Sediment delivery is an important constraint on the sustainable management of coastal lakes along the south coast of New South Wales. Assessment and mitigation of sediment input is a major issue for the sustainable management of water bodies such as coastal lakes and soil erosion caused by rainfall and runoff is of particular concern. In this paper we examine the application of 210Pb analyses of sediment samples to test the extent to which a modified version of the Universal Soil Loss Equation for Australian conditions (OxMUSCLE) is valid. The model is applied to Lake Wollumboola to estimate sediment yield from the catchment into its terminal lake, which is a saline coastal lake 172 km south of Sydney. 14 refs., 1 fig., 1 tab

  3. Application of the 210Pb-dating technique to establish a chronological framework of trace element and heavy metal contamination resulting from the impact of European settlement in estuarine systems of the Sydney Basin, Australia

    The estuaries of Georges River and Hacking River, partly located in suburban Sydney, are at significant risk of contamination by heavy metal and trace element pollutants associated with urban/industrial development. The object of the current work is to correlate changes in land use resulting from European settlement with chemical changes observed in soil sediments. At each location core samples were taken and selected slices analysed for 226Ra and 210Po using alpha spectrometry. The 226Ra activity equates to the supported 210Pb activity and the 210Po activity equates to the total 210Pb activity. The difference between the total and the supported 210Pb is the excess 210Pb activity. Once the excess 210Pb has been layed down in the sediment its activity at depth (assuming the core to be undisturbed) is solely a function of its half-life and the initial amount present; a circumstance which readily affords the calculation of a sedimentation rate. Owing to its relatively short half-life (22.26 year) the 20Pb dating technique can be used to date sediments as far back as about 120 years. In Australia this time frame would cover most of the period of European settlement

  4. Determination of 210Pb e 210Po in marine samples and aerosols

    In this work the methodologies for 210Pb e 210Po analyses in marine samples, such as fish, seaweed, sediment, and aerosol samples are presented. The 210Pb levels in the samples were obtained by both210Bi and 210Po ingrowth. The 210Pb analysis via 210Bi presents the following steps: 210Pb leaching from samples with 8 M nitric acid and hydrogen peroxide; lead sulphate precipitation; conversion to carbonate; dissolution; lead sulphate precipitation; gravimetric analysis of lead; waiting of time to reach radioactive equilibrium and 210Bi beta counting by employing a Geiger-Mueller detector with a low background radiation. The 210Pb analysis via 210Po presents the following steps: 210Pb and 210Po leaching from samples with 8 M nitric acid and hydrogen peroxide; nitric acid elimination by heating and hydrochloric acid addition; spontaneous deposition onto silver disc and alpha counting of polonium in silicon surface-barrier detector. In order to determine 210Pb activity, the solution was percolated in the Dowex AG 1-X 8 anion exchange resin; preconditioned with 8 M nitric acid; the lead was eluted by 8 M hydrochloric acid; the solution was gently evaporated to dryness and diluted with 0.5 N hydrochloric acid. After 3-6 months a second 210Po spontaneous deposition onto silver disc was carried out. The methodology for 210Pb analysis via 210Bi showed lead recoveries from 63 to 100%. In the method via 210Po the polonium recoveries were varied from 39 to 63% under manual agitation, and from 60 to 100% under mechanical agitation. The radiochemical methods for 210Po and 210Pb analyses were applied in reference samples from International Atomic Energy Agency (IAEA) and the results obtained showed the good precision and accuracy of the established methods. The analysis of marine sediment samples of Antarctica presented 210Pb and Po levels from 8 to 60 Bq.kg-1, and fish samples from Sao Paulo Coast presented 210Po levels from 0.5 to 5.3 Bq.kg-1. These results for fish are

  5. Measurement and Meteorological Analysis of 7Be and 210Pb in Aerosol at Waliguan Observatory

    ZHENG Xiangdong; WAN Guojiang; CHEN Zunyu; TANG Jie

    2008-01-01

    Beryllium-7 (7Be) and lead-210 (210Pb) activities were measured from October 2002 to January 2004 at Waliguan Observatory (WO: 36.287 N, 100.898 E, 3816 m a.s.l (above sea level) in northwest China. 7Be and 210Pb activities are high with overall averages of 14.7 3.5 mBq m-3 and 1.8 0.8 mBq m-3 respectively. For both 7Be and 210Pb, there are significant short-term and seasonal variations with a commonly low value in summer (May-September) and a monthly maximum in April (for 7Be) and in December (for 210Pb). The ratio of 7Be/210Pb showed a broad maximum extending from April to July, coinciding with a seasonal peak in surface ozone (O3). The seasonal cycles of 7Be and 210Pb activities were greatly influenced by precipitation and thermal dynamical conditions over the boundary layer, especially for 210Pb. The vertical mixing process between the boundary layer and the aloft air modulates the variations of 7Be and 210Pb at WO in summer. It is indicated that air mass had longer residence time and originated from higher altitudes at WO in the spring-summer time and the winter in 2003. During an event with extremely high weekly-averaged 7Be concentration (24.8 mBq m-3) together with high O3 levels and low water mixing ratio, we found that air masses had been convectively transported a long distance to WO from high latitude source regions in central Asia, where significant subsiding motions were observed. In another case with the extreme 210Pb activity of 5.7 mBq m-3 high CO2 level and specific humidity (in winter), air masses had come from south China and north Indian regions where 222Rn activities were high. This study, using 7Be and 210Pb as atmospheric tracers, has revealed that complex interactions of convective mixing from the upper troposphere and long-range transports exist at WO.

  6. Preparation of low level sealed 210Pb source for random pulse generator

    We have developed the random pulse generator (RPG) that utilizes alpha-particle detection with pin photodiode (PPD). In order to support an expected large market of RPG, a steady production system of weak (about 100 Bq) alpha sealed source is necessary, and, for such alpha-source, 210Pb-210Po source is the best candidate on a viewpoint of environmental radioactivity impact. Two methods for such 210Pb-210Po sealed source preparation, namely direct deposition from isopropyl alcohol solution (IPA solution) of 210Pb-210Po nitrate (D-IPA method) and the 210Pb-210Po hydroxides precipitation (PPT method), were experimentally examined. In the former D-IPA method, an aliquot of IPA solution of 210Pb-210Po nitrate was directly dropped in a sealed cap for PPD and dried by heating. Then, a polycarbonate (PC) solution of 1/1 mixture of dichloromethane and dichloroethane was dropped on the source to make a thin (about 0.1 mg/cm2) film for radioactivity sealed. In the PPT method, 210Pb-210Po hydroxide was filtrated on a PC membrane filter (Nuclipore 0.1 μm) and the membrane filter was dissolved in a 1/1 mixture of dichloromethane and dichloroethane. The sealed 210Pb-210Po sources were prepared directly by dropping an aliquot of the solution into the PPD cap followed by its evaporation. The sealed sources thus prepared were subjected to 1m height fall-down test, air blowing test, and water immersion test. It was confirmed that no radioactive contaminants were coming off from the sealed source through these tests. (author)

  7. Accurate measurements of {sup 210}Pb in industrial wastes for environmental radiation risk assessment purpose

    Bonczyk, Michal; Michalik, Boguslaw [Central Mining Institute, Silesian Centre for Environmental Radioactivity, Plac Gwarkow 1, 40-166 Katowice (Poland)

    2014-07-01

    Lead {sup 210}Pb is a naturally occurring radioactive nuclide element of the uranium ({sup 238}U) radioactive series. It is produced as a result of the decay of so-called short-lived progenies of {sup 222}Rn, i.e. {sup 214}Po (99.98%) and {sup 214}Bi by {sup 219}Tl (0.02%). Activity concentration of lead {sup 210}Pb could vary independently from parent radionuclides due to its physical and chemical properties, especially, due to its half-life (T{sub 1/2} = 22,3 years). Hence, its behaviour in natural environment is very complex and difficult in forecasting. Lead {sup 210}Pb in substantial amount occurs in mining, gas and oil extraction industry wastes, which are deposited in natural environment very often. Due to lack of secular equilibrium proper radiation risk assessment requires accurate concentration of {sup 210}Pb in such materials. The laboratory measurements seem to be the only reliable method in environmental radioactivity monitoring. One of the methods is gamma-ray spectrometry, which is very fast and cost-effective method to determine {sup 210}Pb concentration. On the other hand, the self-attenuation of gamma ray from {sup 210}Pb (46,5 keV) is significant and not depends only on sample density as well the chemical composition (sample matrix) is crucial. Current work describes how the self-attenuation correction factors in the case of {sup 210}Pb concentration analysis in mining wastes are important when environmental radiation risk assessment is carried out. The measurements were done for such industrial wastes as mine sediments which contain significant amount of elements with high Z-number (Barium, Lead, etc.) Experimentally obtained correction factors range between 0.51-6.96 cm{sup 2}/g. Neglecting this factor can cause a significant error or underestimations in radiological risk assessment. (authors)

  8. Distributions of 137Cs and 210Pb in moss collected from Belarus and Slovakia

    In the present work, moss samples collected in Slovakia and Belarus were assayed with respect to gamma-emitting radionuclides. The results for 137Cs and 210Pb are discussed. Moss was used for the first time in Belarus, as a biological indicator of radioactive environmental pollution in consequence of the Chernobyl accident in 1986. In Belarus, the maximum activity of 137Cs was observed in the Gomel region near Mazyr (6830 Bq/kg) and the minimum activity in the Vitebsyevsk Region near Luzhki-Yazno (5 Bq/kg). “Hot spots” were also observed near the towns Borisow and Yuratsishki. The results of measurements of 137Cs in moss samples collected in 2000, 2006 and 2009 in the same localities of Slovakia are presented and compared with the results of air monitoring of 137Cs carried out in Slovakia from 1977 until 2010. Measurements of the 210Pb concentration in moss samples collected over the territory of Slovakia showed, that the median value exceed 2.3 times median value of 210Pb obtained for Belarus moss. For that reason, the inhalation dose for man from 210Pb and 137Cs in Slovakia is more than twice as high as in Belarus, in spite of the initially very high 137Cs exposure in the latter country. -- Highlights: ► Belarus moss was used as a biological indicator of 137Cs and 210Pb. ► Comparison with concentration of 137Cs and 210Pb in moss from Slovakia. ► Moss samples reflect the original distribution of Chernobyl fallout in Belarus. ► Regular decrease of the annual average activity of 137Cs in surface air in Slovakia. ► Median concentration of 210Pb in moss from Belarus is 2.3 times lower than in Slovakia

  9. Decay/ingrowth uncertainty correction of 210Po/210Pb in seawater

    Due to increasing application of 210Po/210Pb in studying particle dynamics, a consistent procedure and calculation to derive accurate and precise result of 210Po and 210Pb in seawater should be proposed in the framework of intercalibration by GEOTRACES. The associated uncertainty of radioactivity, which is a significant component of data report, plays a vital role in intercomparison and should be well evaluated. Although measurement uncertainty of laboratory result was well defined in ISO standards and IAEA technical documents, the decay/ingrowth uncertainty correction from laboratory result to in-situ result was less studied. It was demonstrated that the relative uncertainty of in-situ 210Pb activity was independent of elapsed time and equal to relative uncertainty of laboratory measuring 210Po activity at second spontaneous deposition date. The relative uncertainty of in-situ 210Po activity decreases with in-situ activity ratio of 210Po to 210Pb and increases with elapsed time between sampling date and separation date, relative uncertainty of laboratory measuring 210Po activity at first spontaneous deposition date and relative uncertainty of in-situ 210Pb activity. It was more important to improve precision of 210Po at first spontaneous deposition date than that of 210Po at second spontaneous deposition date. To obtain a desirable relative uncertainty of in-situ 210Po activity, the maximum allowing elapsed time for 210Po, which was important for sampling strategy making and quality assurance, was calculated by in-situ activity ratio of 210Po to 210Pb and precision of analytical method for 210Po. The methodology of decay/ingrowth uncertainty correction could also be applied for other radionuclide pairs (234Th/238U, 90Y/90Sr, 210Bi/210Pb), sample matrixes (aerosols), and disciplines. - Highlights: • Uncertainty of 210Po/210Pb in seawater was comprehensively represented. • Decay/ingrowth uncertainty correction was well quantified and concisely expressed.

  10. Determination of 210Pb activity concentration in ground-level air by gamma-ray spectrometry in Tripoli, Libya

    210Pb activity concentration at ground-level air of Tripoli was determined by gamma-ray spectrometric analysis of 20 particulate samples collected. Each sample, the air filtered through chlorinated vinyl polychloride Petrianow was 78,000 m3 on average. Activity concentrations of 210Pb were ranging from 78-186 μBq x m-3. Estimated effective dose to adult from inhaled 210Pb was calculated to be 2.7 μSv x y-1. (author)

  11. Inhalation of 210Po and 210Pb from cigarette smoking in Poland

    The carcinogenic effect of 210Po and 210Pb with respect to lung cancer is an important problem in many countries with very high cigarette consumption. Poland has one of the highest consumptions of cigarettes in the world. The results of 210Po determination on the 14 most frequently smoked brands of cigarettes which constitute over 70% of the total cigarette consumption in Poland are presented and discussed. Moreover, the polonium content in cigarette smoke was estimated on the basis of its activity in fresh tobaccos, ash, fresh filters and post-smoking filters. The annual effective doses were calculated on the basis of 210Po and 210Pb inhalation with the cigarette smoke. The results of this work indicate that Polish smokers who smoke one pack (20 cigarettes) per day inhale from 20 to 215 mBq of 210Po and 210Pb each. The mean values of the annual effective dose for smokers were estimated to be 35 and 70 μSv from 210Po and 210Pb, respectively. For persons who smoke two packs of cigarettes with higher radionuclide concentrations, the effective dose is much higher (471 μSv yr-1) in comparison with the intake in diet. Therefore, cigarettes and the absorption through the respiratory system are the main sources and the principal pathway of 210Po and 210Pb intake of smokers in Poland

  12. Metabolic balances of 210Pb and 210Po at natural levels

    Metabolic balances of 210Po and 210Pb were determined under strictly controlled dietary conditions in adult males. The intakes of the two nuclides were due to the dietary contents of these radioisotopes, inhalation from the atmosphere, and smoking of cigarettes. No additional radioisotope was given. The mean dietary intake of 210Pb was 1.25 pCi/day and of 210Po, 1.63 pCi/day. The major pathway of excretion of both nuclides is via the gastrointestinal tract; the urinary excretion is much lower. The total excretions of 210Pb and 210Po were greater than the dietary intake and the overall balances were -0.28 and -0.16 pCi/day for the two nuclides, respectively, during a low calcium intake. The 210Pb balances did not change significantly when the calcium intake was increased 7- to 10-fold except for one patient in whom the balance became more negative. The 210Po balance was more negative during calcium intakes of 800 and 2200 mg than during a low calcium intake of 200 mg/day. The urinary and fecal excretions of the two radionuclides were not affected by the intake of sodium fluoride, while the diuretic compound, Hydrodiuril, appeared to decrease the fecal 210Pb excretion

  13. Growth rates in modern speleothems from Santana Cave, Brazil, by the 210Pb-method

    The Santana Cave is located at the Upper Ribeira Touristic State Park (PETAR-Parque Estadual Turístico do Alto Ribeira) in southern São Paulo State, Brazil. This paper describes 210Pb activity concentration data in soda straw stalactites samples collected at Salão das Flores in Santana Cave that is a fossil tributary of the cave river. Non-expensive alpha counting following some analytical steps for extracting and depositing 210Po were used for providing the 210Pb data. In the analyzed samples, 210Pb values of increasingly older samples fitted an exponential curve, thus suggesting that the production of 210Pb has been constant with time. Also, the near-ideal fit indicated that the growth was uniform and there was no break in the continuous growth. The soda straw growth rates were determined from the best fit to the exponential curve through the 210Pb activity concentration. The results of the measurements allowed estimate a longitudinal rate corresponding to 1.3 mm/yr and a lateral rate of 0.01 mm/yr, which permitted calculate times of 70 years and 317–498 years for their formation, respectively. The lateral growth rate is compatible with values from studies of chemical weathering rates held under laboratory and natural conditions.

  14. Detection of 210Pb in the lungs of smokers by in-vivo gamma spectrometry

    Since mainstream smoke is highly enriched in 210Pb, alpha radiation from inhaled cigarette smoke particles has been proposed as a cancer-producing agent in cigarette smokers. 210Po and 210Pb have been observed in tobacco, cigarette smoke and in the lungs of smokers. Since 210Pb is highly enriched in mainstream smoke, there have been estimates of yearly excesses of 210Pb in the lungs of one-pack-a-day smokers of 3 to 10 pCi (0.11 to 0.37 Bq). The ORNL Whole Body Counter was used to verify this estimate by the methodology of high-resolution, in vivo gamma spectrometry. Measurements were made on 113 adult male non-radiation workers who have either smoked at least one pack of cigarettes per day for at least five years, or have never smoked cigarettes. An analysis-of-variance table was generated based on the Pb-ratio for each individual which revealed that there was no statistically significant increase in the amount of 210Pb in the lungs of smokers over those of non-smokers. Sources of error are also discussed

  15. Atmospheric deposition patterns of (210)Pb and (7)Be in Cienfuegos, Cuba.

    Alonso-Hernández, Carlos M; Morera-Gómez, Yasser; Cartas-Águila, Héctor; Guillén-Arruebarrena, Aniel

    2014-12-01

    The radiometric composition of bulk deposition samples, collected monthly for one year, February 2010 until January 2011, at a site located in Cienfuegos (22° 03' N, 80° 29' W) (Cuba), are analysed in this paper. Measurement of (7)Be and (210)Pb activity concentrations were carried out in 12 bulk deposition samples. The atmospheric deposition fluxes of (7)Be and (210)Pb are in the range of 13.2-132 and 1.24-8.29 Bq m(-2), and their mean values are: 56.6 and 3.97 Bq m(-2), respectively. The time variations of the different radionuclide have been discussed in relation with meteorological factors and the mean values have been compared to those published in recent literature from other sites located at different latitudes. The annual average flux of (210)Pb and (7)Be were 47 and 700 Bq m(-2) y(-1), respectively. Observed seasonal variations of deposition data are explained in terms of different environmental features. The atmospheric deposition fluxes of (7)Be and (210)Pb were moderately well correlated with precipitation and well correlated with one another. The (210)Pb/(7)Be ratios in the monthly depositions samples varied in the range of 0.05-0.10 and showed a strong correlation with the number of rainy days. PMID:25233214

  16. Determination of 210 Pb in mineral spring waters of Aguas da Prata city

    Concentration levels of 210 Pb have been analyzed in 12 mineral spring waters of Aguas da Prata city. The 210 Pb concentration was determined through 210 Bi, by measuring the gross beta activity of the 210 Pb Cr O4 precipitate after separation from interfering elements by complexation with nitrile tri acetic acid at basic pH. The 210 Bi beta activity was carried out in a low background gas flow proportional counter. Concentrations ranging from lower limit of detection to 1240 mBq/L were observed for 210 Pb. The radiochemical procedure adopted presented a chemical yield around 85% and a lower limit of detection of 4,9 mBq/L. Dose calculations were performed in order to evaluate the importance of this radionuclide to the radiation exposure due to the ingestion of these waters. Based upon measured concentrations, committed effective doses up to 1,1 mSv/y and committed doses to the bone up to 1.7 x 101 mSv/y were observed for 210 Pb. (author). 64 refs, 6 figs, 7 tabs

  17. Calibration and measurement of {sup 210}Pb using two independent techniques

    Villa, M. [Centro de Investigacion, Tecnologia e Innovacion, CITIUS, Universidad de Sevilla, Av. Reina Mercedes 4B, 41012 Sevilla (Spain)], E-mail: mvilla@us.es; Hurtado, S. [Centro de Investigacion, Tecnologia e Innovacion, CITIUS, Universidad de Sevilla, Av. Reina Mercedes 4B, 41012 Sevilla (Spain); Manjon, G.; Garcia-Tenorio, R. [Departamento de Fisica Aplicada II, E.T.S. Arquitectura, Universidad de Sevilla, Av. Reina Mercedes 2, 41012 Sevilla (Spain)

    2007-10-15

    An experimental procedure has been developed for a rapid and accurate determination of the activity concentration of {sup 210}Pb in sediments by liquid scintillation counting (LSC). Additionally, an alternative technique using {gamma}-spectrometry and Monte Carlo simulation has been developed. A radiochemical procedure, based on radium and barium sulphates co-precipitation have been applied to isolate the Pb-isotopes. {sup 210}Pb activity measurements were done in a low background scintillation spectrometer Quantulus 1220. A calibration of the liquid scintillation spectrometer, including its {alpha}/{beta} discrimination system, has been made, in order to minimize background and, additionally, some improvements are suggested for the calculation of the {sup 210}Pb activity concentration, taking into account that {sup 210}Pb counting efficiency cannot be accurately determined. Therefore, the use of an effective radiochemical yield, which can be empirically evaluated, is proposed. {sup 210}Pb activity concentration in riverbed sediments from an area affected by NORM wastes has been determined using both the proposed method. Results using {gamma}-spectrometry and LSC are compared to the results obtained following indirect {alpha}-spectrometry ({sup 210}Po) method.

  18. Alpha-spectroscopic determination of 210Pb and 210Po in snow samples

    The concentrations of 210Pb and 210Po in several snow samples were determined using α-spectrometry. After 5 l of snow-melt water was subjected to coprecipitation of both nuclides with AlPO4, the solvent extraction procedure with TBP (tri-butyl phosphate)-isopropyl ether was applied to purify the polonium fraction, followed by the spontaneous electro-deposition on a Ni-sheet. The α-spectrum was measured with a Si(Au)-semiconductor detector coupled with a multichannel pulse-height analyzer. After the first determination of 210Po, the concentration of 210Pb was estimated from second measurement of 210Po grown newly from the remaining Pb-fraction during the storage period of more than 3 months. In these analytical procedures, 212Pb and 208Po tracers were conveniently utilized for the determination of collection yield for 210Pb and of the final chemical yield of 210Po, respectively. The contents of 210Po and 210Pb in the fresh snow were 3 -- 30 mBq/l (81 -- 810 fCi/l) and 250 -- 720 mBq/l(6.8 -- 19.5 pCi/l), respectively, and the residence time of 210Pb was given to be 6 -- 12 days from the decay-growth relationships of both nuclides. (author)

  19. The effect of water treatment on the presence of particle-bound 210Po and 210Pb in groundwater

    The distribution of 210Po and 210Pb in various particle-size fractions in Finnish groundwater was studied at five private homes. Each site had water treatment equipment comprising either an ion exchange unit or a granular activated carbon filter. Samples of both raw and treated water were filtered using pore sizes ranging from 450 nm to 100 kDa and the activity concentration of 210Po and 210Pb in the filtrate was determined. In untreated groundwater 86% of 210Pb, on average, was found in the large particle fraction (> 450 nm). However, in Fe- and Mn-rich water with a high Fe/Mn ratio and in organic-rich water, the majority of 210Pb was found in either the intermediate particle (100 kDa-450 nm) or small particle (210Pb, 210Po was bound more to the intermediate and small particle fraction. After water treatment, 210Pb was found most frequently in the large particle fraction. The size distribution of particle-bound 210Po was not as clear as that for 210Pb, and in treated water, 210Po was more evenly distributed among fractions. The ion exchange unit removed 210Pb and 210Po bound to the intermediate or small particle fraction, whereas the efficiency of the activated carbon filters in removing 210Pb and 210Po was independent of the particle size. (orig.)

  20. 238U, 226Ra and 210Pb in some vent waters of the Galapagos spreading center

    The concentrations of 226Ra, 238U and 210Pb have been measured in waters from the Mussel Bed and the Rose Garden thermal fields at the Galapagos spreading center over a temperature range of approx.2.5--16 0C. The 226Ra-T plots yield slopes of 0.112 and 0.036 dpm/kg 0C for the Mussel Bed and the Rose Garden respectively yielding a global hydrothermal 226Ra flux less than 5% of that required to sustain the oceanic inventory. 238U concentration in waters 0C is the same as that in ambient sea water whereas water hotter than approx.9 0C shows a decreasing trend with temperature to zero 238U at approx.29 0C. 210Pb concentration in Mussel Bed increases with temperature, and extrapolated to approx.350 0C yields a 210Pb concentration considerably less than that expected from 222Rn decay and basalt alteration

  1. Determination of sedimentation rate in Thane creek using 210Pb dating

    Sediments are good representatives of the geochemical history of a particular area. They can be regarded as good archives of environmental processes and their effects. Therefore, the study of sediments in coastal areas has great importance for the understanding of the interaction between human activities and marine systems. The sedimentation process can be correlated with time by assessing decays of radionuclides like 210Pb, 137Cs and 14C in different layers of it. 210Pb and its environmental cycle have been commonly used as environmental tracer in many environmental studies. For assessment of chronological history of pollution in the Mumbai region, sediment samples were collected from Thane creek and sedimentation rates were estimated by measurement of 210Po activity which is in equilibrium with 210Pb

  2. Determination of 210Pb in human skeletal remains from Morocco: implications for time since death assessment

    In forensic contexts, time since death assessment in human skeletal remains is crucial for identification, and both accuracy and reliability are required. In this paper, we present the possibilities and constraints of the use of 210Pb in dating skeletonized human bones in Morocco. The method was tested on recent as well as archaeological bones of known dates of death. A calibration curve was obtained from the available data in the scientific literature. The 210Pb initial activity was introduced as an increasing lineal function with time. The 210Pb dating approach gives promising results only for recent bones. On the contrary, for archaeological bones, the technique has erroneously led to post-mortem intervals in the range of recent bones which constitute a serious limitation of the method. On the other hand, uranium isotopes content in bones is suggested in this work as a possible indicator in placing a studied bone within either a forensic or archaeological context. (author)

  3. Radiometric determination of 210Pb in powder samples by the method of standard additions

    The method of standard additions is a well known procedure in chemistry for the measurements of trace substances. The use of this method is described in the radiometric determination of 210Pb activity via the γ-ray at 46.5 keV emitted in about 4% of the decays. Standard additions of 210Pb activity are absorbed on anion exchange resin which is then mixed with the sample. The procedure used to extract the area of the photopeak from the continuum on which it is superimposed, is described in detail. The value of the 210Pb activity is calculated using the slope and intercept of the best straight line fitting the count-rate data plotted against added activity. Results obtained on four standard ore samples indicate that this method yields results of comparable accuracy to other methods such as β-ray spectrometry of the prompt 210Bi daughter. This method, however, avoids the tedious chemical separations required. (author)

  4. Analysis of 210Pb and 210Po in Brazilian foods and diets

    Radiochemical procedures for the analysis of 210Pb and 210Po in foods and diets are presented. Because of the low beta energy of 210Pb, its analysis was based on a separation of the daughter radionuclide 210Bi by precipitation of lead sulphate, 210Bi ingrowing and beta counting of this nuclide. 210Po analysis was based on wet dissolution of the sample, deposition onto silver disc and counting by alpha-spectrometry. Levels of these radionuclides in individual items and diets of selected university students were determined in order to evaluate the intakes of 210Pb and 210Po as well as the dose due to ingestion of foods and diets in Sao Paulo city. (author)

  5. Temporal variations of 7Be and 210Pb activity in aerosols at Xiamen, China

    Huang, Dekun

    2016-04-01

    The radionuclides serve as powerful tracers to identify and quantify several atmospheric processes, such as source, transport and mixing of air masses, air masses exchanging between various atmospheric layers, residence times of atmospheric gasses and pollutants. 7Be and 210Pb activities in aerosols were measurement from October, 2013 to September, 2015 at Xiamen (24°26'7.44″N, 118°5'31.30″N) in South China. The activity of 7Be and 210Pb in aerosols from 2013 to 2015 in Xiamen ranged from 0.26 to 9.05 (mean:4.15) mBq m-3 and from 0.14 to 2.64 (mean:1.05) mBq m-3, respectively. The mean activity of 7Be was comparable with the activities of other places in the same latitude, while the mean activity of 210Pb was lower than the activity of the locations at high altitudes. The possible reason is that Xiamen is a coastal city located on southwest Pacific. The activities of 7Be and 210Pb had a commonly low value in summer (July-September) and a high value in autumn (October-December), it may be controlled by the rainfall. There is significant relationship between the monthly 210Pb activities and the concentration of PM 2.5 and PM 10. In contrast, monthly 7Be activities only show significant correlation with the concentration of PM 10, which implies that 7Be and 210Pb can be used to trace the different sources of the aerosols. And the dry 7Be depositional fluxes increased with latitude along the coast of China (R2=0.92, n=8).

  6. 210Pb content of rainfall in the Shephela (Israel coastal plain)

    Rainfall at two stations in the Shephela (Israel Coastal Plain) was analyzed for 210Pb during the winter of 1974-75. The highest concentrations of 210Pb were found in samples collected early in the rainy season. It seemed that there was a small, but significant difference between the two stations. The total activity at the Bet-Dagan station (near Tel-Aviv) and generally also the activities in the individual samples collected at this station were lower than the respective activities at the Gan-Shomron station (60 kms to the north)

  7. On the Application of Macros to the Automation of different Dating Models Using ''210 Pb

    Different Dating models based on 210 Pb measurements, used for verifying recent events are shown in this report as well as, models that describe different processes affecting the vertical distribution of radionuclides in lacustrine and marine sediments. Macro-Commands are programmes included in calculation work sheets that allow automatised operations to run. In this report macros are used to: a) obtain 210 Pb results from a data base created from different sampling campaigns b) apply different dating models automatically c) optimise the diffusion coefficient employed by models through standards deviation calculations among experimental values and those obtained by the model. (Author) 21 refs

  8. Determination of {sup 210}Pb and {sup 210}Po in cigarette tobacco; Determinacao de {sup 210}Pb e {sup 210}Po em tabaco de cigarros nacionais

    Peres, Ana Claudia

    1999-07-01

    Cigarette smoking is one of the important pathways that could contribute to enhance the radiation dose to man, due to the relatively large concentrations of {sup 210}Pb and {sup 210}Po found in tobacco leaves. In this work, concentrations of these two radionuclides were determined in eight of the most commercialized cigarette brands produced in Brazil. The samples analyzed were bought randomly in the market. The {sup 210}Pb was determined by counting the beta activity of the {sup 210}Bi in a gas flow proportional detector, after radiochemical separation and precipitation of the PbCr0{sub 4}. The {sup 210}Po was determined by alpha spectrometry, using a surface barrier detector, after radiochemical separation and spontaneous deposition of Po in copper disk. The results showed concentrations ranging from 11,9 to 30,2 mBq per gram of dry tobacco for {sup 210}Pb and from 10,9 to 27,4 mBq per gram of dry tobacco for {sup 210}Po. (author)

  9. {sup 210}Po and {sup 210}Pb in seals from the Baltic Sea and Lake Saimaa, Finland

    Solatie, D.; Rissanen, K. [Radiation and Nuclear Safety Authority - STUK, Rovaniemi (Finland). Regional Laboratory in Northern Finland; Vesterbacka, P. [Radiation and Nuclear Safety Authority - STUK, Helsinki (Finland). Natural Radiation Laboratory

    2005-09-15

    {sup 210}Po and {sup 210}Pb are members of the {sup 238}U decay chain. {sup 210}Po is an {alpha}-emitter with a half-life of 138 days, while its grandmother, {sup 210}Pb is a {beta}-emitter with 22.3 year half-life. In the atmosphere {sup 222}Rn formats its decay products {sup 210}Po and {sup 210}Pb. These nuclides are deposited on to the surface of land and sea and thus enter the food chain. The naturally occurring radionuclides {sup 210}Po and {sup 210}Pb are important because their great contribution to radiation dose to human and other species. As top predators in the aquatic food chain, fish-eating seals are vulnerable to the accumulation of contaminants. In the Regional Laboratory in Northern Finland, measurements of {sup 210}Po and {sup 210}Pb activity concentrations in seals from the Baltic Sea and in ringed seals from Lake Saimaa have been performed. Concentrations of {sup 210}Po and {sup 210}Pb in seals were determined in muscle, liver, kidney and spleen. The results of {sup 210}Po and {sup 210}Pb activity concentrations and the ratio of {sup 210}Po / {sup 210}Pb in these samples are presented. (Summary-only contribution)

  10. Retention and tissue distribution of 210Pb (NO3)2 administered orally to infant and adult monkeys

    The retention and tissue distribution of 210Pb were studied in 10-day-old, 150-day-old, and adult monkeys. Lead-210 nitrate was administered to the monkeys by gavage after a 12 hr fast and 210Pb excreted in urine and feces was monitored for 96 hr. All monkeys were necropsied 96 hr after dosing and the 210Pb concentrations of various tissues were deermined. The data demonstrated that infant monkeys retained 64.5 and 69.8% of the orally administered 210Pb at 10 and 150 days of age, respectively, while adult monkeys retained 3.2% of the 210Pb dose. Blood 210Pb levels 96 hr after dosing did not vary significantly between age groups. Of the 210Pb contained in blood, 98 to 99% was found in blood cells and 1 to 2% in blood plamsa; 5 to 8% of the Pb in blood cells was bound to blood cell membranes. None of these parameters varied significantly with age. The percentage of the lead dose excreted in urine did not vary significantly between age groups. Analysis of tissues for 210Pb revealed that both the tissue Pb concentrations and tissue Pb : blood Pb ratios were significantly higher in the bone structure of infants than adults. Brain Pb : blood Pb ratios were significantly greater in 10-day-old infants than 150-day-old infants or adults

  11. Unusually large 210Po deficiencies relative to 210Pb in the Kuroshio Current of the East China and Philippine seas

    Three vertical water profiles of 210Pb and 210Po have been measured in the East China and Philippine seas. All the profiles show a large 210Po deficiency of ∼ 8 dpm/cm2 relative to 210Pb in the top ∼ 1,000 m of the water column. Based on the 210Po deficiency, the steady state flux for 210Po removal from the surface water is estimated to be 14 dpm cm-2/yr. The 210Po/210Pb ratio of sinking particles will be too high unless an additional source of 210Pb into the surface is accounted for. Thus the large 210Po deficit is probably caused by the increased atmospheric input of 210Pb without any significant 210Po, which is focused in the Kuroshio region by isopycnal transport, and the preferential scavenging of 210Po relative to 210Pb by settling particles. The transient model calculations indicate that the model can account for the observed high excess 210Pb inventory and large 210Po deficiency in the water column if focusing of atmospherically derived 210Pb in the Kuroshio water is a factor of 2-3 more than the local input. Such lateral redistribution by the western North Pacific gyre circulation is not inconsistent with the deeper penetration and the high water column inventories of anthropogenic substances observed in this region

  12. 210Pb: bioaccumulation factor and internal radiation dose to the public due to consumption of seafood from Mumbai harbour bay

    Marine organisms such as fishes, molluscs and crustaceans are known to accumulate 210Pb. Distribution of 210Pb in coastal marine organisms mainly fishes and shell fishes is studied. Concentration of 210Pb obtained in muscle of common fishes (edible portion) varied from BDL to 9.71 ± 0.92 Bq kq-1 wet muscle. For fishes like Pampus argenteus (pomfret), Cynoglossus elongatus (sole), Rastrelliger kanagurta (mackerel), Harpoden nehereus (Bombay duck), Arius dussumieri (catfish), the concentration factors for 210Pb in edible portion of fish from sea water works out to 101 to 103. Radiation dose to the public has been evaluated on the basis of daily intake of 40 g of fish (15 kg y-1). Committed effective dose (CED) to 210Pb due to consumption of seafood is calculated, CED varied from 2.5 x 10-3 to 1.27 x 10-1 mSv y-1. (author)

  13. 210Pb-derived ages for the reconstruction of terrestrial contaminant history into the Mexican Pacific coast: Potential and limitations

    210Pb is widely used for dating recent sediments in the aquatic environment; however, our experiences working in shallow coastal environments in the Pacific coast of Mexico have demonstrated that the potential of 210Pb for reliable historical reconstructions might be limited by the low 210Pb atmospheric fallout, sediment mixing, abundance of coarse sediments and the lack of 137Cs signal for 210Pb corroboration. This work discusses the difficulties in obtaining adequate sedimentary records for geochronological reconstruction in such active and complex settings, including examples of 210Pb geochronologies based on sediment profiles collected in two contrasting areas coastal areas (mudflats associated to coastal lagoons of Sinaloa State and the continental shelf of the Gulf of Tehuantepec), in which geochemical data was used to support the temporal frame established and the changes in sediment supply recorded in the sediment cores which were related to the development of land-based activities during the last century.

  14. Technologically enhanced 210Pb and 210Po in iron and steel industry

    Iron and steel manufacture has been ranked as the largest industrial source of environmental contamination in the USA; the wastes generated in their production processes contain heavy elements that can be a source of contamination, and natural radionuclides that can produce an occupational and/or public radiological impact. In this work the potential occupational effective dose rate (μSv/y) due to inhalation in four integrated steel-making factories from Egypt has been evaluated, by assuming a well defined scenario and with basis in the 210Pb and 210Po activity concentrations determined in ore and wastes collected in the aforementioned factories. Activity concentrations, in Bq/kg, of 210Pb and 210Po, and leachable Pb and Fe were measured using gamma-ray spectrometry based on HPGe detector, alpha particle spectrometry based on PIPS detector, and inductively coupled plasma-mass spectrometry (ICP-MS). Levels of 210Pb and 210Po in the range of 210Pb and 210Po radionuclides. → Both radionuclides are enriched through the thermal processes. → For radiation dose assessment inhalation would be the main route of exposure.

  15. Levels of lead-210 (210Pb) and polonium 210 (210Po) in Cuban Tobacco products

    The release of 210Po in tobacco smoke and the radiation dose for man have been studied because of the high incidence of lung cancer among smoker. The electroplating of polonium at two different times onto copper disks and further measurement of alpha activity was the meted used for 210 Po determination in tobacco products. The Polonium daughter is used to determine both the 210Pb and 210Po using the Baseman equations for radioactive growth and decay. A cigarette contains between 10.6 and 14.7 mBq of 210Pb with an average activity of 13.0 mBq and between 8.5 and 12.3 mBq of 210Po with an average activity of 10.4 mBq for different Cuban cigarette brands. For a person smoking a pack of 20 cigarettes a day, the values of intakes estimated range from 32 to 44 mBq for 210Pb and from 34 to 49 mBq for 210 Po with an average daily intake of 39 mBq for 210 Pb and 42 mBq for 210Po. The annual effective dose estimated due to inhalation of these nuclides contained in cigarette smoke shows a value of 66[Sv and was in correspondence with world-wide range dose, 46 - 90 mSv.year 1 - for tobacco product consumption

  16. Lead precipitation fluxes at tropical oceanic sites determined from 210Pb measurements

    Concentrations of lead, 210Pb, and 210Po were measured in rain selected for least influence by local sources of contamination at several tropical and subtropical islands (Enewetak; Pigeon Key, Florida; and American Samoa) and shipboard stations (near Bermuda and Tahiti). Ratios expressed as ng Pb/dpm 210Pb in rain were 250--900 for Pigeon Key (assuming 12% adsorption for 210Pb and no adsorption for lead), depending on whether the air masses containing the analyzed rain came from the Caribbean or from the continent, respectively; about 390 for the northern Sargasso Sea downwind from emissions of industrial lead in North America; 65 for Enewetak, remote from continental emissions of industrial lead in the northern hemisphere; and 14 near Tahiti, a remote location in the southern hemisphere where industrial lead emissions to the atmosphere are much less than in the northern hemisphere. (The American Samoa sample yielded a higher ratio than Tahiti; the reason for this is not clear but may be due to local Pb sources). The corresponding fluxes of lead to the oceans, based on measured or modeled 210Pb precipitation fluxes, are about 4 ng Pb/cm2y for Tahiti, 10 for Enewetak, and 270 for the Sargasso Sea site, and between 110 to 390 at Pigeon Key

  17. Determination of 210Pb at ultra-trace levels in water by ICP-MS

    210Pb (t 1/2 = 22.26 years) is one of the most difficult naturally occurring radionuclides to analyze directly via radiometric measurement due to its low-energy radioactive decay. In this work, inductively coupled plasma mass spectrometry (ICP-MS) was investigated as a possible alternative to radiometric counting for the determination of 210Pb. The formation of isobaric and polyatomic (molecular) interferences was studied and various strategies (i.e. co-precipitation, extraction chromatography, and derivatization) were tested to assess their usefulness in reducing these interferences. In addition, the potential of these strategies as pre-concentration methods was demonstrated. A 210Pb pre-concentration of >300-fold and recoveries of 63-73% were obtained using a combined co-precipitation and extraction chromatography protocol followed by derivatization using an ethylating reagent. The abundance sensitivity at m/z = 210 in the presence of stable Pb was also investigated for three types of mass spectrometers (sector-field (ICP-SFMS), quadrupole-based (ICP-QMS), and quadrupole-based with a dynamic reaction cell (ICP-QMS (DRC))). Finally, the method was applied to determine 210Pb in water samples and a detection limit of 90 mBq L-1 (10 pg L-1) was obtained

  18. Concentrations of 207Bi and 210Pb-210Bi-210Po disequilibrium in fish

    Radioactive 207Bi, produced during nuclear testing at the Pacific Proving Grounds, concentrates in the muscle tissue and organs of goatfish and certain pelagic lagoon fish from Bikini and Enewetak Atolls. It is reasonable to expect that fish capable of accumulating 207Bi could also be efficient accumulators of other bismuth isotopes - namely 210Bi, the daughter of naturally occurring 210Pb. Therefore, 210Bi and consequently 210Po, the decay product of 210Bi, would be expected in notable excess over the precursor 210Pb in specific tissues. To test this assumption, we compared concentrations of 210Pb, 210Bi, and 210Po in muscle, liver, and bone separated from some reef species from the Marshall Islands. Concentrations of 210Bi in muscle and liver were found to exceed those of its precursor by factors of 2 to 15. The excess 210Bi in some species, however, is not from the environmental sources (either food or water) from which 207Bi is derived. The data suggest that the excess 210Bi may be translocated to muscle and liver tissue following the decay of 210Pb in bone

  19. The 226 Ra, 210 Pb and essential elements bioavailability to pines at Urgeirica uranium mill tailings

    The objective of this study is to correlate the uptake of the natural radionuclides 226Ra and 210Pb with the essential elements, potassium, calcium and magnesium in the pines growing at the 'Urgeirica uranium mill tailings. It can be concluded that the potassium, calcium and magnesium mean concentration ratio values are, about two to three orders of magnitude, higher than the values obtained to 226Ra and 210Pb for pines growing on the Urgeirica uranium mill tailings. The concentration ratio values higher than 1 obtained to the potassium, calcium and magnesium elements indicate that pines are behaving as accumulators to these elements. Contrarily, the 226Ra and 210Pb concentration ratio values lower than 1 indicates that pines are behaving as excluders to these radionuclides. So, it can be concluded that this kind of plants is not suitable to a phyto remediation strategy. In general, a marginally significant correlation was observed between the potassium, calcium and magnesium concentrations, the cation-exchange capacity and the ph in the tailings and the 226Ra and 210Pb pines/tailings concentration ratios. (N.C.)

  20. Bioavailability of radionuclides {sup 226}Ra, {sup 228}Ra and {sup 210}Pb present in the brazilian phosphate fertilizers and phosphogypsum; Avaliacao da biodisponibilidade dos radionuclideos {sup 226}Ra, {sup 228}Ra e {sup 210}Pb presentes nos fertilizantes fosfatados e no fosfogesso de procedencia nacional

    Russo, Ana Carolina

    2013-08-01

    Phosphogypsum, also called gypsum, by-product of the phosphate fertilizer industry, can be used as soil conditioner since it provides improvements in the soil-plant system. However, this by-product concentrates radionuclides of the U and Th series, present in the phosphate rock used as raw material, which can impact the environment. In order to study the bioavailability of radionuclides, samples of phosphogypsum and phosphate fertilizers (monoammonium phosphate and triple superphosphate) were analyzed. The concentration of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb were determined by gamma spectrometry. The samples were leached with a mild EDTA solution and the radionuclides present in the final solution were determined by total alpha and beta counting on a gas flow proportional counter. The percentage of extraction varied from 1.6% to 1.7% for {sup 210}Pb, from 0.5% to 1.4% for {sup 226}Ra and from 0.1% to 1.0% for the {sup 228}Ra in phosphogypsum samples. The low percentage of extraction obtained for the radionuclides can be partly explained by the low solubility of phosphogypsum, which ranged from 7.7% to 16%. For the monoammonium phosphate samples the percentage of extraction were less than 26% for {sup 226}Ra, less than 10% for '2{sup 28}Ra and less than 10% for {sup 210}Pb. In spite of the high solubility of 77% of monoammonium phosphate in the EDTA solution, low concentrations of radionuclides were observed in the leached solution. For the triple superphosphate samples, the percentage of extraction was 2.3% for {sup 226}Ra, 1.2% for {sup 228}Ra and 11.3% for {sup 210}Pb. In spite of the high solubility of 66% of triple superphosphate in the EDTA solution, low concentrations of radionuclides were observed in the leached solution. (author)

  1. Export of particulate matter from Tokyo Bay studied with radiochemical tracers, 210Po and 210Pb

    Sediment traps were deployed at the mouth of Tokyo Bay in the winter of 1991 and the summer of 1993, each for a few days. The fluxes of total mass, 210Pb (parent) and 210Po (daughter) increased with depth, especially in the near-bottom layer. All the fluxes of total mass, 210Po and 210Pb decreased offshore at the same depth, while they increased offshore at the same distance above the bottom. The observed particulate flux of 210Pb in the water column was one to two orders of magnitude larger than the sedimentation rate at the bottom. The activity ratio of 210Po/210Pb in the near-bottom layer was largest at each station and did not vary from station to station. These findings indicate that enormous amounts of particulate matter are transported fairly quickly offshore through the near-bottom layer at the entrance. The variation in total mass flux was well synchronized with the tidal cycle at a mid-depth of 85 m in the water column of 240 m in winter of 1991, where the fluxes were larger during ebb and smaller during flood tides. The particulate flux of 210Po was also larger by a factor of about 2 during ebb, while the concentration of 210Pb was about 40 % larger during flood than ebb. These findings indicate that the tidal current is a major conveyor of particulate matter at the mid-depths. The tidal variation, however, was weak for the results obtained in the near-bottom layer in 1993, where much particulate matter was transported toward the Kuroshio region along the valley of Tokyo Bay. Our results suggest that even bays having narrow mouths, such as Tokyo Bay, are a large source of particulate material to the open oceans. (author)

  2. Organic carbon sedimentation rates in Asian mangrove coastal ecosystems estimated by {sup 210}PB chronology

    Tateda, Y.; Wattayakorn, G.; Nhan, D.D.; Kasuya, Y. [Abiko Research Laboratory CRIEPI, Biology Dept., Abiko, Chiba (Japan)

    2004-07-01

    Organic carbon balance estimation of mangrove coastal ecosystem is important for understanding of Asian coastal carbon budget/flux calculation in global carbon cycle modelling which is powerful tool for the prediction of future greenhouse gas effect and evaluation of countermeasure preference. Especially, the organic carbon accumulation rate in mangrove ecosystem was reported to be important sink of carbon as well as that in boreal peat accumulation. For the estimation of 10{sup 3} years scale organic carbon accumulation rates in mangrove coastal ecosystems, {sup 14}C was used as long term chronological tracer, being useful in pristine mangrove forest reserve area. While in case of mangrove plantation of in coastal area, the {sup 210}Pb is suitable for the estimation of decades scale estimation by its half-life. Though it has possibility of bio-/physical- turbation effect in applying {sup 210}Pb chronology that is offset in case of 10{sup 3} years scale estimation, especially in Asian mangrove ecosystem where the anthropogenic physical turbation by coastal fishery is vigorous.In this paper, we studied the organic carbon and {sup 210}Pb accumulation rates in subtropical mangrove coastal ecosystems in Japan, Vietnam and Thailand with {sup 7}Be analyses to make sure the negligible effect of above turbation effects on organic carbon accumulation. We finally concluded that {sup 210}Pb was applicable to estimate organic carbon accumulation rates in these ecosystems even though the physical-/bio-turbation is expected. The measured organic carbon accumulation rates using {sup 210}Pb in mangrove coastal ecosystems of Japan, Vietnam and Thailand were 0.067 4.0 t-C ha{sup -1} y{sup -1}. (author)

  3. Determination of 210Pb and 210Po in Brazilian cigarette tobacco

    Cigarette smoking is one of the important pathways that could contribute to enhance the radiation dose to man, due to the relatively large concentrations of 210Pb and 210Po found in tobacco leaves. In this work, concentrations of these two radionuclides were determined in eight of the most commercialized cigarette brands produced in Brazil. The samples analyzed were bought randomly in the market. The 210 Pb was determined by counting the beta activity of the 210Bi in a gas flow proportional detector, after radiochemical separation and precipitation of the PbCrO4. The 210Po was determined by alpha spectrometry, using a surface barrier detector, after radiochemical separation and spontaneous deposition of Po in copper disk. The results showed concentrations ranging from 15,8 to 30,2 mBq per gram of dry tobacco for 210Pb and from 18,8 to 27,4 mBq per gram of dry tobacco for 210Po. Taking in account the experimental error of the measurements, radioactive equilibrium between 210Pb and 210Po is observed for all analyzed samples. This result was expected, since the delayed time from the harvest of tobacco leaves to the introduction of cigarettes in the market is enough to reach that equilibrium. Assuming a 20 cigarettes per day consumption, and a 10% of Pb and 20% of Po being inhaled by the primary smokers, it is obtained a value of yearly intake of 11,3 Bq of 210Pb and 21,2 Bq of 210Po, due to cigarette consumption. These values lead to an increment to the committed effective dose of 0,025 mSv year-1 and an increment to the probability of getting cancer of 1 x 10-6 per year. (author)

  4. Budget and residence time of 210Pb along the Gulf of Lion's continental slope (Northwestern Mediterranean Sea)

    Concentration of 210Pb has been measured in water and sediment trap samples collected on 7 experimental sites representative of the Gulf of Lion's continental margin. This marine system is characterised by a major continental input through the Rhone river and a powerful along-slope cyclonic current (Northern Current). From the distribution of bulk 210Pb activities, it was intended to gain some information on the processes controlling the transport of trace metals at the ocean/continent boundary. Residence times of 210Pb relative to scavenging in surface waters (0-100 m) showed a constant along-slope (i.e., downstream) decrease that can be related to increasing concentrations in suspended particles. Annual time-series of 210Pb activities in settling particles were determined on samples collected by traps at 500 and 1000 m depth. From this data set, a budget for 210Pb on this margin was established which permitted to determine the flux of 210Pb theoretically adsorbed onto particles. This theoretical flux was compared, at each site, with fluxes effectively measured by traps and revealed that exchange processes - mainly in the form of large inputs of this nuclide (import of 47 to 93% of measured flux) - largely affect the 210Pb distribution on this continental margin. (author)

  5. Bioaccumulation and retention of 210Pb in the Mediterranean mussel Mytilus galloprovincialis

    Pb is commonly reported as a pollutant of concern in the marine environment. Although severely regulated in the industrialised countries, global emissions are not showing a significant downward trend. Therefore Pb will still cause problems because of its conservative nature and its increasing use in some industrial applications. It is therefore important to develop tools to monitor the occurrence and abundance of Pb in coastal waters, particularly those in less-developed regions of the world where its use is not yet, or only poorly, regulated. Thus, the purpose of this study was to quantify Pb bioaccumulation in a widely distributed and abundant species along the Mediterranean coasts of North Africa, i.e. the mussel Mytilus galloprovincialis, in order to assess the relevance of its use as a bioindicator species of Pb contamination. The experimental approach used highly sensitive nuclear detection techniques to investigate uptake and loss kinetics of the radiotracer 210Pb in the mussels. Individuals were exposed experimentally to the radiotracer for 14 d via seawater (uptake phase). At the end of the exposure period, non-contaminated conditions were restored (clean flowing sea water) for 22 d and loss kinetics of 210Pb from mussel tissues were determined (depuration phase) during that time. 210Pb was found to be readily taken up according to linear uptake kinetics. At the end of the exposure period (14 d of exposure), calculated concentration factors reached values as high as 300. When mussels were exposed to increasing 210Pb activities (0.25 to 2.5 Bq ml-1), it was found that Pb bioaccumulation in the mussel tissues was directly proportional to ambient Pb concentrations in sea water. Retention of the metal in mussel tissues was high with ca. 50% of incorporated Pb remaining in the tissues after 3 weeks of depuration. Mussels displayed similar loss kinetics regardless the 210Pb activity (0.25 to 2.5 Bq ml-1) to which they were previously exposed. Estimated

  6. Modeling the downward transport of (210)Pb in Peatlands: Initial Penetration-Constant Rate of Supply (IP-CRS) model.

    Olid, Carolina; Diego, David; Garcia-Orellana, Jordi; Cortizas, Antonio Martínez; Klaminder, Jonatan

    2016-01-15

    The vertical distribution of (210)Pb is commonly used to date peat deposits accumulated over the last 100-150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of (210)Pb within some peat profiles. In this study, we introduce the Initial Penetration–Constant Rate of Supply (IP-CRS) model for calculating ages derived from 210Pb profiles that are altered by an initial migration of the radionuclide. This new, two-phased, model describes the distribution of atmospheric-derived (210)Pb ((210)Pbxs) in peat taking into account both incorporation of (210)Pb into the accumulating peat matrix as well as an initial flushing of (210)Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous (210)Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used (210)Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. (241)Am and (137)Cs). Our results showed that the IP-CRS can provide chronologies from peat records where (210)Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene. PMID:26476062

  7. 7Be, 210Pb, and 210Po in the surface air from the Arctic to Antarctica

    In the present study we have investigated the activity concentrations of 210Pb, 210Po as well as 7Be in surface air of the North and South Atlantic (1988–1989), the Arctic Ocean (1991), and along the coastline of Siberia (1994) during succeeding expeditions in the Swedish Polar Research program. During the cruises in the Arctic Ocean during 1991-07-28 to 1991-10-04 the average air concentrations of 7Be was 0.6 ± 0.4 mBq/m3, 210Pb 40 ± 4 μBq/m3 and 210Po-38 ± 10 μBq/m3. During the Swedish-Russian Tundra Ecology-94 expedition along the Siberian coastline the average air concentrations of 7Be and 210Pb measured during May–July were 11 ± 3, and 2.4 ± 0.4 mBq/m3, and during July–September they were 7.2 ± 2 and 2.7 ± 1.1 mBq/m3 respectively. The results from measurements of the activity concentration of 210Pb in the air over the Arctic Ocean vary between 75 and 176 μBq/m3. In the air close to land masses, however, the activity concentration of 210Pb in the air increases to 269–2712 μBq/m3. The activity concentration of 7Be in the South Atlantic during the cruise down to Antarctica varied between 1.3 and 1.7 with an average of 1.5 ± 0.8 mBq/m3. The activity concentration of 210Pb in the South Atlantic down to Antarctica varied between 6 and 14 μBq/m3. At the Equator the activity concentration recorded in November 1988 was 630 μBq/m3 and in April 1989 it was 260 μBq/m3. The average activity concentration of 210Pb during the route Gothenburg–Montevideo in 1988 was 290 and on the return Montevideo–Gothenburg it was 230 μBq/m3. The activity concentration of 210Po in the South Atlantic down to Antarctica varied between 15 and 58 μBq/m3. At the Equator the activity concentration in November 1988 was 170 and in April 1989 it was 70 μBq/m3. The average activity concentration of 210Po during the route Gothenburg–Montevideo in 1988 was 63 and on the return Montevideo–Gothenburg it was 60 μBq/m3. The average of the activity concentrations in the

  8. Application of Radionuclide 210 Pb in Dating of Black Coral%应用210 Pb 的南海黑角珊瑚定年

    张晓笛; 毕倩倩; 蔡炜颖; 王希龙; 张芬芬; 杜金洲

    2015-01-01

    通过高分辨低本底的α能谱检测技术对采自南海西沙群岛(JYI-1、JYI-2)和鹿回头半岛(LHT)三株黑角珊瑚骨骼中的210 Pb 进行了测定,利用过剩210 Pb 比活度在珊瑚横截面的径向分布规律,对黑角珊瑚进行年代学研究。结果表明,210 Pb 在珊瑚骨骼中的比活度随径向呈指数衰减,各样品中210 Pb 的比活度范围分别为10.28~73.41 mBq/g (JYI-1),1.50~4.72 mBq/g (JYI-2)和5.35~12.67 mBq/g (LHT)。这些黑角珊瑚物种都表现出了生长缓慢、生长周期长的特性。它们持续生长了约185~267 a,年生长率介于17.8~26.5μm/a。而且,年生长率在不同种属、不同区域的样品间有明显区别,生长速率的顺序为:西沙(JYI-2)>西沙(JYI-1)>鹿回头(LHT)。放射性核素210 Pb 对南海黑角珊瑚定年结果与生长环计数的定年结果基本一致。这种黑角珊瑚定年方法可以为其在百年尺度上研究气候环境的演变和重建提供基础数据。%In this study,theαspectrometry technology was used to estimate the activities of 2 1 0 Pb in the skeletons of black corals collected from the Xisha Islands (JYI-1,JYI-2 )and Luhuitou Peninsula (LHT)of the South China Sea.According to the radial distribution characteristics of excess 2 1 0 Pb in the cross-sections of black corals,we studied the chronology of black corals.The results reveal that specific activity of 2 1 0 Pb exhibits an exponential decrease with distance from the edge of the black corals.The ranges of 2 1 0 Pb specific activity in the coral skeleton are 10.28-73.41 mBq/g,1.50-4.72 mBq/g and 5.35-12.67 mBq/g in the JYI-1,JYI-2 and LHT respectively.All black corals are long-lived and slow-growing organisms.They have been growing continuously for 185-267 a,with growth rates ranging from 17.8 to 26.5 μm/a.Moreover,the annual growth rates exhibit obvious distinction in diverse species collected from different regions.The sequence of the growth rate is JYI-2 >JYI-1>LHT.With respect

  9. 210Po/210Pb disequilibria in the shelf edge of the East China Sea

    The uranium-238 series radionuclides 210Pb (t1/2 = 22.3 yr) and its daughter 210Po (t1/2 = 138 days), are important tracers in the marine environment. They are especially useful for studies on material transport scavenging processes within relatively short times and on the mechanism of material transport from coastal zones to the open sea, because they are highly reactive to the particulate matter and is rapidly removal from the water column. In this study, we present measurements of 210Po and 210Pb concentrations in seawater and the calculated rates of removal of these radionuclides from the water column in the shelf edge of the East China Sea

  10. Chronology of sedimentation in Cienfuegos bay, elucidated from 210Pb and 137Cs

    This article present the results of the use of radiotracers in geochronology technique for evaluate the anthropogenic impact on Cienfuegos Bay, Cuba. The excess 210Pb and 137Cs radionuclides were measurements on one sediment corer collected in Cienfuegos Bay using a gravity core. Each core was sliced and pre treatment for gamma spectrometric measurements and other complementary analyses. It was applied the Constant Rate Supply model for dating the 210Pb profile and it was used the 137Cs as an alternative method for dating calibration. The results show a good agreement between CRS method's results and 1963's 137Cs peak. Spatial and temporal evaluation of the radiotracers profiles have shown that sedimentation rate have changed in the last fourth years and it is associated to the economical and industrial development. It was demonstrated the significance of radiotracers in environmental impact on estuaries and semi enclosed bays

  11. Efficiency testing of Red Lake protection dam on Rosu stream by 210Pb method

    The Red lake, a small lake from Romania is threatened by massive sedimentation, therefore two protection dams were constructed on Oii and Rosu brooks. The aim of this study is to get information about the variation of the retention capability of the dams using the 210Pb method. 210Pb, 226Ra and 137Cs were measured by gamma- and 210Po by alpha spectrometry. The values for mass sedimentation are between 0.17 ± 0.03-2.3 ± 0.4 g/cm2y for the Red Lake and 0.21 ± 0.03-0.9 ± 0.1 g/cm2y for the dam lake. Due to these high values, the dam lake will fill up in 20 ± 8y and 80 % of the Red Lake in 81 ± 30y. (author)

  12. Stable (206Pb, 207Pb, 208Pb) and radioactive (210Pb) lead isotopes in 1 year of growth of Sphagnum moss from four ombrotrophic bogs in southern Germany: Geochemical significance and environmental implications

    Shotyk, William; Kempter, Heike; Krachler, Michael; Zaccone, Claudio

    2015-08-01

    behaviour of 210Pb and total Pb in the mosses may reflect differences in the particle size distribution of the corresponding aerosols, their physical and chemical properties, the extent of their interaction with plant surfaces, or some combination of these factors. The 206Pb/207Pb ratios from NBF (HO = 1.159 ± 0.002, n = 19; WI = 1.157 ± 0.003, n = 48) and OB (GS = 1.157 ± 0.003, n = 28; KL = 1.159 ± 0.003, n = 15) are uniform and indicate that both regions are impacted by Pb from predominately anthropogenic sources. Although Sphagnum moss represents an established receptor in monitoring atmospheric Pb deposition, the physical characteristics (size, morphology, composition) of the three predominant kinds of Pb-bearing aerosols considered here, namely 210Pb (adsorbed onto aerosol surfaces, following decay of 222Rn), anthropogenic Pb (sub-micron aerosols from high temperature combustion processes) and lithogenic Pb soil-derived mineral dusts (tens of microns, from chemical weathering of crustal rocks), are fundamentally different and these have consequences for the retention efficiency of the three kinds of particles.

  13. Biogeochemical cycling of 210Po and 210Pb in the upper ocean

    The naturally occurring radionuclide 210Po is typically deficient relative to its parent 210Pb in the surface ocean due to preferential removal by biota, while in near equilibrium or excess below the surface mixed layer due to rapid regeneration from sinking organic matter. In general, larger deficit of 210Po is observed in the oligotrophic oceans interior, which seems to be due to efficient uptake of Po by cyanobacteria. The activities of 210Pb and 210Po were measured for the truly dissolved (< 10 kD), colloidal (10 kD - 0.45 mm), and particulate (> 0.45 mm) phases in the upper ocean (0-200 m) of the East/Japan Sea (EJS) in the summer of 2009. The total 210Pb and 210Po activities in the EJS were in the range of 6.3-23 and 3.3-10 dpm/100L, respectively. The proportions of the truly dissolved, colloidal, and particulate phases were 35±3, 48±7 and 17±8% for 210Pb and 19±2, 36±6, and 45±6% for 210Po, respectively, in the upper ocean. Using a net residence time model, which accounts for biological uptake and remineralization, the residence times of 210Po in the upper 100-m layer were calculated to be 92±41, 63±14, and 166±45 days for the truly dissolved, colloidal, an particulate phases, respectively. The residence time of colloidal 210Po was several-fold longer than typical turnover times (<10 days) of high-molecular-weight dissolved organic carbon and colloidal residence times of short-live 234Th in the surface water. This result suggests that 210Po turns over several times through the colloidal phase perhaps together with other bio-reactive elements, before settling down from the upper ocean. (author)

  14. Variability of excretion rates of 210Pb and 210Po of humans at environmental levels

    Variability of the excretion rates of the nuclides 210Pb and 210Po at natural levels was studied in a group of samples collected from men maintained under the carefully controlled conditions of a metabolic ward. They consumed only the standard diet of the ward in which they had been resident for at least several months prior to this study. The mean urinary rates were about 0.1 to 0.5 pCi/day for both 210Pb and 210Po, while fecal rates ranged from 1 to 2.7 pCi/day for the two nuclides. For urinary 210Pb the coefficients of variation (ratio of standard deviation to mean) for three subjects ranged from 19 to 45 percent for eight continuous 24-hr samples compared to 11 to 13 percent for subsequently collected multiday samples (4 to 9 days each) for each subject. However, the standard errors of the means for the one day collections were about equal to the standard deviations of the pooled samples. Similar variability was noted for the 210Po data. Six day fecal collections from these time periods exhibited higher variabilities than did the urine, from about 12 percent to 50 percent for each of the nuclides. Multiday collections for 12 subjects showed mean coefficients of variation of about 16 percent for 210Pb and 13 percent for the 210Po for urine and 21 and 25 percent, respectively, in fecal collections. Since dietary intake was maintained fairly constant, excreta collections were carefully controlled, and the analytical precision was about 5 percent, these variabilities appear to be due to biological variations and are characteristic of the individuals studied. Some possible causes of these effects are discussed

  15. Discharge of 210Po and 210Pb in coastal groundwater to the ocean

    The activities of 210Po and 210Pb were measured for the truly dissolved (<10 kDa) and colloidal (10 kDa - 0.45 ìm) phases in coastal ground water in 2010 and 2011. The sampling sites include the coast of a large tidal flat (Hampyeong Bay) and a volcanic island, Jeju, Korea, where submarine groundwater discharge (SGD) were reported to be higher than typical continental margins. The total dissolved fraction was separated into the colloidal and truly dissolved fractions using a tangential flow filtration (TFF) system (PLCGC Pellicon). The total 210Po and 210Pb activities in ground water were 1.0 - 18.2 dpm/100L (9.7±7.6 dpm/100L) an 2.9 - 29.1 dpm/100L (16.8±10.7 dpm/100L) in the Hampyeong Bay and Jeju Island samples, respectively. The total 210Po and 210Pb activities in groundwater were similar to or even slightly lower than those in the typical seawater. These lower activities seem to be due to the rapid adsorption of Po and Pb on to particles in the subterranean estuary. The proportions of the truly dissolved and colloidal phases were, respectively, 73±5% and 27±5% for 210Po, and 60±5% and 40±5% for 210Pb. This result is consistent with the earlier study that more than half of the some dissolved trace metals in coastal ground water are in the colloidal form. Thus, our result implies that the colloidal forms are important in controlling the behaviour of Po, Pb, and other trace metals in the subterranean estuary and SGD-associated fluxes to the ocean. (author)

  16. Minimum speed limit for ocean ridge magmatism from 210Pb-226Ra-230Th disequilibria.

    Rubin, K H; van der Zander, I; Smith, M C; Bergmanis, E C

    2005-09-22

    Although 70 per cent of global crustal magmatism occurs at mid-ocean ridges-where the heat budget controls crustal structure, hydrothermal activity and a vibrant biosphere-the tempo of magmatic inputs in these regions remains poorly understood. Such timescales can be assessed, however, with natural radioactive-decay-chain nuclides, because chemical disruption to secular equilibrium systems initiates parent-daughter disequilibria, which re-equilibrate by the shorter half-life in a pair. Here we use 210Pb-226Ra-230Th radioactive disequilibria and other geochemical attributes in oceanic basalts less than 20 years old to infer that melts of the Earth's mantle can be transported, accumulated and erupted in a few decades. This implies that magmatic conditions can fluctuate rapidly at ridge volcanoes. 210Pb deficits of up to 15 per cent relative to 226Ra occur in normal mid-ocean ridge basalts, with the largest deficits in the most magnesium-rich lavas. The 22-year half-life of 210Pb requires very recent fractionation of these two uranium-series nuclides. Relationships between 210Pb-deficits, (226Ra/230Th) activity ratios and compatible trace-element ratios preclude crustal-magma differentiation or daughter-isotope degassing as the main causes for the signal. A mantle-melting model can simulate observed disequilibria but preservation requires a subsequent mechanism to transport melt rapidly. The likelihood of magmatic disequilibria occurring before melt enters shallow crustal magma bodies also limits differentiation and heat replenishment timescales to decades at the localities studied. PMID:16177787

  17. 210Pb and compositional data of sediments from Rondonian lakes, Madeira River basin, Brazil

    Gold exploration has been intensive in Brazilian Amazon over the last 40 years, where the use of mercury as an amalgam has caused abnormal Hg concentrations in water bodies. Special attention has been directed to Madeira River due to fact it is a major tributary of Amazon River and that since 1986, gold exploration has been officially permitted along a 350 km sector of the river. The 210Pb method has been used to date sediments taken from nine lakes situated in Madeira River basin, Rondônia State, and to verify where anthropogenic Hg might exist due to gold exploitation in Madeira River. Activity profiles of excess 210Pb determined in the sediment cores provided a means to evaluate the sedimentation rates using a Constant Flux: Constant Sedimentation (CF:CS) and Constant Rate of Supply (CRS) of unsupported/excess 210Pb models. A significant relationship was found between the CF:CS sedimentation rates and the mean values of the CRS sedimentation rates (Pearson correlation coefficient r=0.59). Chemical data were also determined in the sediments for identifying possible relationships with Hg occurring in the area. Significant values were found in statistical correlation tests realized among the Hg, major oxides and Total Organic Carbon (TOC) content in the sediments. The TOC increased in the sediment cores accompanied by a loss on ignition (LOI) increment, whereas silica decreased following a specific surface area raising associated to the TOC increase. The CRS model always provided ages within the permitted range of the 210Pb-method in the studied lakes, whereas the CF:CS model predicted two values above 140 years. - Highlights: • Gold mining activities. • Madeira River basin at Amazon area. • Pb-210 chronological method. • Models for evaluating sedimentation rates

  18. Optimizing production of Pb beams for 205,210Pb analysis by Accelerator Mass Spectrometry

    Sookdeo, Adam; Cornett, Jack; Kieser, William E.

    2015-10-01

    The measurement of rare radioactive lead isotopes (205Pb or 210Pb) by AMS requires the production of strong Pb negative molecular anion beams from the ion source. This paper summarizes the results of tests of different target composition on the strength and stability of 208PbF3- currents and 210Pb counts. In an 834 SIMS-type Cs+ sputter source, the superhalogen, PbF3- had the largest current or ionization efficiency from a survey of Pb molecular anions. The target matrix that produced the largest current of PbF3- was composed of PbF2, AgF2 and CsF. The ratio of AgF2 and CsF does not affect the ionization efficiency of PbF3-. Chemically refluxed targets of PbF2, AgF2 and CsF increased the ionization efficiency of PbF3-. The count rate of the rare isotope, 210Pb, was increased with the addition of microgram quantities of stable PbF2 to the targets. In an SO-110 type Cs+ sputter source the ionization efficiency of PbF3- was increased with lower rather than higher Cs+ fluence.

  19. Evaluation of 210Pb and 210Po in cigarette tobacco produced in Brazil

    Cigarette smoking is one of the pathways that might contribute significantly to the increase in the radiation dose reaching man, due to the relatively large concentrations of 210Pb and 210Po found in tobacco leaves. In the present study, the concentrations of these two radionuclides were determined in eight of the most frequently sold cigarette brands produced in Brazil. 210Pb was determined by counting the beta activity of 210Bi with a gas flow proportional detector after radiochemical separation and precipitation of PbCrO4. 210Po was determined by alpha spectrometry using a surface barrier detector after radiochemical separation and spontaneous deposition of Po on a copper disk. The results showed concentrations ranging from 11.9 to 30.2 mBq per gram of dry tobacco for 210Pb and from 10.9 to 27.4 mBq per gram of dry tobacco for 210Po. The collective committed effective dose resulting from the use of cigarettes produced in Brazil per year is estimated to be 1.5x104 man-Sv

  20. Concentration of 210Po and 210Pb in the diet at the Marshall Islands

    The concentrations of 210Po and 210Pb have been determined in many local foods consumed by societies residing on different atolls in the Marshall Islands. The average daily intake of these two naturally occurring radionuclides from local and imported food is estimated to be 2.18 and 0.36 Bq, respectively. Local foods contribute 87% of the 210Po and 47% of the 210Pb associated with the diet. The items contributing the majority of the activity to the diet are derived from the marine environment and include parts of fish, invertebrates, seabirds and eggs of seabirds. The committed effective dose from ingestion of 210Po and 210Pb is 2 mSv/year (200 mrem/year). This pathway now contributes 83% of the natural background irradiation received by residents in the Marshall Islands. Because the naturally occurring radionuclides are omnipresent in terrestrial and marine foods at all atolls, the annual intake and computed dose can be considered as typical values for individuals with comparable diets and inhabiting other islands in the Pacific

  1. Unusual 210Po/210Pb ratios in the surface water of the Gulf of Lions

    Concentrations of 210Po and 210Pb have been measured in sea water collected in the Grand Rhone Canyon. Concentrations of 210Pb are at similar levels to those found in other Mediterranean sea water samples, and are at the levels which would be expected in comparison with global sea water data. The same applies to the 210Po concentrations in samples from below 100 m depth. Surface samples from above 100 m have 210Po at levels rather higher than expected, and their 210Po/210Pb ratios are about 1 or more as compared with the usual open ocean ratio 0.5. These data can be interpreted as indicating another source of supply of 210Po to the surface layer in addition to the normal atmospheric input. We suggest that an episodic advective particulate input, probably originating in the output of the Rhone river and perhaps involving resuspension of fine particulates from the bottom sediments as a result of storm conditions, is he most likely candidate for this additional source. (authors)

  2. Measurement of 210Pb and its Application to Evaluate Contamination in an Area Affected by NORM Releases

    Liquid scintillation counting (LSC) is an easy and straightforward technique, and combined with its low limit of detection, makes it a powerful tool for both routine and low level measurements that can be applied to 210Pb low level counting in environmental samples. 210Pb can be easily measured following a sulphate co-precipitation method; the addition of a carrier and the weighing of the recovered amount is a widespread technique to evaluate radiochemical yield, however, this evaluation of the recovery is sometimes questioned. The samples employed in this work were recollected in 1999 and 2005 from the estuary of the Odiel and Tinto rivers (SW of Spain), which were affected by phosphogypsum (pg.) discharges until 1998. Phosphogypsum contains most of the 210Pb from the treated raw material, for that reason analysed riverbed sediments have enhanced 210Pb activity concentrations and hence, enhanced activity concentration of its daughter 210Po, both in secular equilibrium after two years

  3. A method for analyzing low statistics high resolution spectra from 210Pb in underground coal miners from Brazil

    A survey conducted by the IRD-CNEN determined that some workers from an underground coal mine in the south of Brazil were exposed to elevated airborne concentrations of 222Rn. Because inhalation of high airborne concentrations of 222Rn can lead to an increase of 210Pb in bone, in vivo measurements of 210Pb in the skeleton were performed in selected underground workers from this mine. Measurements were performed using an array of high-resolution germanium detectors positioned around the head and knee to detect the low abundant 46.5 keV photon emitted by 210Pb. The gamma-ray spectra were analyzed using a moving median smoothing function to detect the presence of a photopeak at 46.5 keV. The minimum detectable activity of 210Pb in the skeleton using this methodology was 50 Bq. (author)

  4. Ingestion of 210 Pb and 210 Po through fish consumption in the Cananeia-Iguape system, Sao Paulo State, Brazil

    In this work the ingestion of 210 Pb and 210 Po in the Cananeia - Iguape System, coast south of the Sao Paulo State was estimated. After the dissolution of the fish muscle (by microwave) radiochemical methods were applied for the analysis of those radionuclides.210 Pb was detected by using a Geiger-Muller detector while 210 Po by alpha spectrometry. The estimates of individual ingestion of 210 Pb and 210 Po for the fish of higher economical importance for the population of the System were of 0.004 and 0.035 Bq.d-1, respectively. Although, the levels of individual ingestion of these radionuclides obtained in this work are below the recommended levels it is advisable a periodic monitoring of these radionuclides in estuarine samples, especially, for the organisms such as fish that can be used as bio-indicators of 210 Pb and 210 Po. (author)

  5. A Comparison of Tow Nuclear Analytical Techniques for determination of 210PB Specific Activity in Solid Environmental Samples

    Two nuclear analytical techniques for determination of 210Pb-specific activity in solid environmental samples have been validated and compared. The first technique depends on determination of 210Pb via its alpha emitting daughter 210Po using alpha-particle spectrometry, while the second technique is based on direct determination of 210Pb by measuring its activity at the 46-keV gamma line by low-energy gamma-ray spectrometry. Detection limits, repeatability, reproducibility, and surrogate recovery were the main validation parameters. Measurement uncertainties were estimated and compared for both techniques. Results of this study have shown that the expected activity of 210Pb in the environmental samples and the required measurement uncertainty are the main factors influencing a selection of the appropriate method for the application. (author)

  6. Assessment of 210Po and 210Pb in marine biota of the Mallipattinam ecosystem of Tamil Nadu, India

    To provide baseline data on background radiation levels for the future assessment of the impact of nuclear and thermal power stations, a systematic study was carried out in the Mallipattinam ecosystem of Tamil Nadu, India. Mallipattinam is located between the Kudankulam and Kalpakkam nuclear power plants and near to Tuticorin thermal power plant. Water, sediments, seaweeds, crustaceans, molluscs, and fish were collected to measure the concentrations of 210Po and 210Pb. The concentrations of 210Po and 210Pb in most samples are comparable to values reported worldwide. In fish, the concentrations of 210Po and 210Pb are in the range 16-190 Bq kg-1 and 8-153 Bq kg-1, respectively. The concentration factors of 210Po and 210Pb for the biotic components ranges from 103 to 106.

  7. Measurement of {sup 214} Pb, {sup 212} Pb {sup 210} Pb and {sup 7} Be activities in sizes fractionated aerosols in the lower atmosphere at Sacavem (Lisbon)

    Reis, Mario J.; Brogueira, Alfredo L.; Bettencourt, Antonio O. [Instituto Tecnologico e Nuclear, Sacavem (Portugal). Dept. de Protecao Radiologica e Seguranca Nuclear; Rosa, Rui N. [Universidade de Evora (Portugal). Dept. de Fisica

    2001-07-01

    Aerodynamic size distribution measurements of {sup 214} Pb, {sup 212} Pb {sup 210} Pb and {sup 7} Be were carried out using a five-stage high-volume cascade impactor with effective cut-off diameters of 0.49, 0.95, 1.5, 3.0, and 7.2 {mu}m. The activity of the samples was measured by {gamma}-ray spectrometry using both coaxial and ultra-low background well-type HPGe detectors. The activity size distribution measurements indicate that all radionuclides were associated with submicron aerosol in the accumulation mode, being {sup 210} Pb and {sup 7} Be attached to slightly larger particles, when compared to short-lived radon and thoron daughters. The mass size distributions show a significant contribution from aerosol particles larger than 7.2 {mu}m to the total mass concentration, which indicates the occurrence of resuspension processes. However, since that in most of the samples no {sup 210} Pb and short-lived {sup 214} Pb and {sup 212} Pb were found in association with larger particles, it seems that those nuclides were mostly originated by the decay of atmospheric radon (or thoron in the case of {sup 212} Pb) instead of soil resuspension. On average it was observed that about 80% of the {sup 214} Pb and {sup 212} Pb activity was associated with aerosol particles with aerodynamic diameters smaller than 0.49 {mu}m and about 90% with particles smaller than 0.95 {mu}m. (author)

  8. Atmospheric residence time of (210)Pb determined from the activity ratios with its daughter radionuclides (210)Bi and (210)Po.

    Semertzidou, P; Piliposian, G T; Appleby, P G

    2016-08-01

    The residence time of (210)Pb created in the atmosphere by the decay of gaseous (222)Rn is a key parameter controlling its distribution and fallout onto the landscape. These in turn are key parameters governing the use of this natural radionuclide for dating and interpreting environmental records stored in natural archives such as lake sediments. One of the principal methods for estimating the atmospheric residence time is through measurements of the activities of the daughter radionuclides (210)Bi and (210)Po, and in particular the (210)Bi/(210)Pb and (210)Po/(210)Pb activity ratios. Calculations used in early empirical studies assumed that these were governed by a simple series of equilibrium equations. This approach does however have two failings; it takes no account of the effect of global circulation on spatial variations in the activity ratios, and no allowance is made for the impact of transport processes across the tropopause. This paper presents a simple model for calculating the distributions of (210)Pb, (210)Bi and (210)Po at northern mid-latitudes (30°-65°N), a region containing almost all the available empirical data. By comparing modelled (210)Bi/(210)Pb activity ratios with empirical data a best estimate for the tropospheric residence time of around 10 days is obtained. This is significantly longer than earlier estimates of between 4 and 7 days. The process whereby (210)Pb is transported into the stratosphere when tropospheric concentrations are high and returned from it when they are low, significantly increases the effective residence time in the atmosphere as a whole. The effect of this is to significantly enhance the long range transport of (210)Pb from its source locations. The impact is illustrated by calculations showing the distribution of (210)Pb fallout versus longitude at northern mid-latitudes. PMID:27132252

  9. Scavenging and fractionation of particle-reactive radioisotopes 7Be, 210Pb and 210Po in the atmosphere

    Chen, Jinfang; Luo, Shangde; Huang, Yipu

    2016-09-01

    The scavenging and fractionation of 7Be, 210Pb, and 210Po in the atmosphere are investigated by measuring their activities in rainwater collected from 68 rain events during March 2004 to April 2006 at a coastal station of Xiamen, southeastern China. In addition to documenting the large temporal variations in activities, fluxes, and isotope ratios of 7Be, 210Pb and 210Po in rainwater and the role of rainfall intensity in radionuclide scavenging, our results show that an enhanced deposition of 7Be and 210Pb occurs in the spring than in other seasons and is attributed to the "funnel effect" due to the increased atmospheric vertical convective mixing in the spring. This latter hypothesis is further supported by the observed seasonal and inter-annual variations in 7Be/210Pb and 210Po/210Pb ratios showing that the weakening of vertical convective mixing or stratosphere-troposphere exchange (STE) at the study site is linked with the enhancement of summer monsoons. It appears that the rainfall intensity, in connection with the vertical (e.g., STE) and horizontal (summer monsoons) air transport, exerts an important control on the activities, fluxes, and isotope ratios of 7Be, 210Pb, and 210Po in the atmosphere. Application of the observational data to a theoretical model shows that there are significant fractionations among 7Be, 210Pb, and 210Po in the atmosphere, with the scavenging rate constant or reciprocal of the residence time of radionuclide in the atmosphere being 210Pb > 7Be > 210Po. A revised Poet et al. (1972)'s method is proposed for quantitative constraint on the scavenging behavior of radionuclide, aerosols, and aerosol-associated trace pollutants in the atmosphere.

  10. Natural radionuclides 210Po and 210Pb in the Delaware and Chesapeake Estuaries: modeling scavenging rates and residence times

    During the spring and summer months of 2012, 210Po and 210Pb activity were measured in the dissolved and particulate phases from the Delaware and upper Chesapeake estuaries. The upper Delaware estuary, near the freshwater end member, was characterized by high-suspended matter concentrations that scavenged dissolved 210Po and 210Pb. Box models were applied using mass balance calculations to assess the nuclides residence times in each estuary. Only 60% of the dissolved 210Po and 55% of the dissolved 210Pb from the Delaware estuary were exported to coastal waters. A large fraction of soluble 210Po and 210Pb within the estuary was either reversibly adsorbed onto suspended particles, trapped in sediment accumulation zones (such as intertidal marshes), bioaccumulated into phytoplankton and discharged to the coastal ocean. The upper Chesapeake estuary was largely characterized by sub-oxic bottom waters that contained higher concentrations of dissolved 210Po and 210Pb, hypothesized to be subjected to redox cycling of manganese. The Delaware and Chesapeake estuary mean residence times for 210Po differed significantly at 86 ± 7 and 126 ± 10 days respectively, while they were similar for 210Pb (67 ± 6–55 ± 5 days). The difference in residence times corresponds to the greater extent of biogeochemical scavenging and regeneration processes within the upper Chesapeake. - Highlights: • Estuarine 210Pb and 210Po data reveal key biogeochemical processes and rates. • Delaware Bay displays regional differentiation due to dominant particle reactions. •Chesapeake Bay displays vertical differentiation from deep sub-oxic redox cycling. • Parent (210Pb) grand-daughter (210Po) disequilibria evidence principle processes. • Net scavenging residence times calculated weeks (Delaware) to months (Chesapeake)

  11. Dating of sediments from four Swiss prealpine lakes with 210Pb determined by gamma-spectrometry: progress and problems

    In this paper the most important problems in dating lake sediments with unsupported 210Pb are summarized and the progress in gamma-spectrometry of the unsupported 210Pb is discussed. The main topics of these studies concern sediment samples preparation for gamma-spectrometry, measurement techniques and data analysis, as well as understanding of accumulation and sedimentation processes in lakes. The vertical distributions of artificial (137Cs, 241Am, 239Pu) and natural radionuclides (40K, 210,214Pb, 214Bi) as well as stable trace elements (Fe, Mn, Pb) in sediment cores from four Swiss lakes were used as examples for the interpretation, inter-comparison and validation of depth–age relations established by three 210Pb-based models (CF-CSR, CRS and SIT). The identification of turbidite layers and the influence of the turbidity flows on the accuracy of sediment dating is demonstrated. Time-dependent mass sedimentation rates in lakes Brienz, Thun, Biel and Lucerne are discussed and compared with published data. - Highlights: • State-of-the-art aspects of gamma-spectrometry of unsupported 210Pb are summarized. • Reduction of 222Rn loss by sealing sediment samples was experimentally quantified. • 210Pb models (CF-CSR, CRS, SIT) are applied on long sediment cores from 4 lakes. • Results for profiles, depth–age relations and sedimentation rates are compared. • 210Pb dating is supported by independent time-markers (7Be, 137Cs, 241Am, 239Pu)

  12. Deposition of [sup 210]Pb, [sup 137]Cs, [sup 239+240]Pu, [sup 238]Pu, and [sup 241]Am in the Antarctic peninsula area

    Roos, P.; Holm, E.; Persson, R.B.R. (Lund Univ. (Sweden). Dept. of Radiation Physics); Aarkrog, A.; Nielsen, S.P. (Risoe National Lab., Roskilde (Denmark))

    1994-01-01

    [sup 210]Pb, [sup 137]Cs, [sup 239+240]Pu, [sup 238]Pu, and [sup 241]Am were analysed in lichen, moss, grass and soil samples, as well as in lake sediments, from the South Shetland Islands, the Antarctic, in order to evaluate the flux and deposition of these elements. Average inventories of the analysed radionuclides in 1988 are given. The ratios [sup 238]Pu/[sup 239+240]Pu and [sup 241]Am/[sup 239+240]Pu of 0.21 [+-] 0.04 and 0.35 [+-] 0.08 respectively agree well with expected values in this area. A significant difference in [sup 137]Cs/[sup 239+240]Pu ratios between lichens and moss/grass/soil is observed which may be an effect of submerging and melt water altering radionuclide ratios. From one of three lakes studied it is possible to perform [sup 210]Pb dating with reasonable accuracy showing an average annual sediment accumulation in this lake of about 45 g m[sup -2]. (author).

  13. Bioavailability pf radionuclides {sup 226}Ra, {sup 228}Ra and {sup 210}Pb present in Brazilian phosphogypsum and phosphate fertilizers

    Russo, Ana Carolina; Saueia, Catia H.R.; Mazzilli, Barbara P., E-mail: chsaueia@ipen.br [Instituto de Pesquisas Energeticas e Nucleares(IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    Phosphogypsum (PG) is a by-product of phosphate fertilizers industries. The USEPA classified PG as a - Technologically Enhanced Naturally Occurring Radioactive Material (TENORM). Its worldwide production on 2006 was estimated in 150 million tons. Annually the three main phosphate industries in Brazil are responsible for 5.5x106 tons of phosphogypsum, which is stored in stacks. The level of radionuclides present in phosphogypsum is well-known and makes its disposal or reutilization an environmental concern. Part of this byproduct can be reused, for example, to improve fertility of agricultural soils. To assess the long term environmental impact of radioactive contamination of ecosystems, information on source term including radionuclide speciation, mobility and biological uptakes have high importance. This paper intends to evaluate the bioavailability of the radionuclides {sup 226}Ra, {sup 228}Ra and {sup 210}Pb to the environment by following a procedure established by the EC (European Community), which includes a single EDTA-NH{sub 4} 0.05M extraction at pH 7.0 prior to the analyses. These results is compared with the total activity concentration of these radionuclides in Brazilian PG and the most used phosphate fertilizers (SSP, TSP, MAP and DAP). This procedure intends to represent on a more realistic way the leaching of radionuclides from PG and fertilizers to soil and agricultural products. (author)

  14. Bioavailability pf radionuclides 226Ra, 228Ra and 210Pb present in Brazilian phosphogypsum and phosphate fertilizers

    Phosphogypsum (PG) is a by-product of phosphate fertilizers industries. The USEPA classified PG as a - Technologically Enhanced Naturally Occurring Radioactive Material (TENORM). Its worldwide production on 2006 was estimated in 150 million tons. Annually the three main phosphate industries in Brazil are responsible for 5.5x106 tons of phosphogypsum, which is stored in stacks. The level of radionuclides present in phosphogypsum is well-known and makes its disposal or reutilization an environmental concern. Part of this byproduct can be reused, for example, to improve fertility of agricultural soils. To assess the long term environmental impact of radioactive contamination of ecosystems, information on source term including radionuclide speciation, mobility and biological uptakes have high importance. This paper intends to evaluate the bioavailability of the radionuclides 226Ra, 228Ra and 210Pb to the environment by following a procedure established by the EC (European Community), which includes a single EDTA-NH4 0.05M extraction at pH 7.0 prior to the analyses. These results is compared with the total activity concentration of these radionuclides in Brazilian PG and the most used phosphate fertilizers (SSP, TSP, MAP and DAP). This procedure intends to represent on a more realistic way the leaching of radionuclides from PG and fertilizers to soil and agricultural products. (author)

  15. Analytical Performance of 14 Laboratories Taking Part in Proficiency Test for the Determination of Caesium-137 and Total Lead-210 in Spiked Soil Samples

    One of the most widespread threats to agricultural development is soil erosion. Soil erosion further impoverishes low-income farm households by reducing soil quality and consequently agricultural yields. It also affects productivity in irrigated farming systems by contributing suspended sediment to waterways and reducing storage capacity of reservoirs. The costs of these effects are substantial in many developing and developed countries. To combat soil erosion there is an urgent need for reliable quantitative data on the extent and rates of soil erosion and sedimentation. Fallout radiouclides (FRN) 210Pb and 137Cs are widely used for soil erosion and sedimentation studies. FRN measurements for soil redistribution involve gamma analysis on soil samples. It is therefore important that the analytical data are correct to ensure that the conclusions of such studies are based on reliable and validated analytical results and to ensure the comparability of the results of different countries. Through a collaboration between the Chemistry Unit and the Soil Science Unit of the IAEA's laboratories IAEA organized an intercomparison exercise in order to assess the validity and reliability of the analytical measurements of 137Cs and total 210Pb carried out by the different laboratories participating in the IAEA Co-ordinated Research Project D1.50.08 'Assessing the effectiveness of soil conservation measures for sustainable watershed management using fallout radionuclides' lead by the Soil Water Management and Crop Nutrition Section of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. In this proficiency test 90 samples (Proficiency Test (PT) materials) were distributed to the participating laboratories. The laboratories were requested to analyse the samples employing the same methods used in their daily routine gamma measurements. In total 14 out of 18 initially registered laboratories reported their results. The analytical results of the laboratories

  16. Distribution of 210Pb and 210Po concentrations in wild berries and mushrooms in boreal forest ecosystems

    The activity concentrations and distribution of 210Pb and 210Po in wild berries and edible mushrooms were investigated in Finnish forests. The main study areas were located in Scots pine (Pinus sylvestris L.) forests in southern and northern Finland. The activity concentrations of 210Pb and 210Po in blueberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) samples decreased in the order: stems > leaves > berries (i.e. fruits). The activity ratios of 210Po/210Pb in the wild berry samples were mainly higher than one, indicating elevated activity concentrations of polonium in the samples. In mushrooms the activity concentrations of 210Pb and especially 210Po were higher than in fruits of the wild berries. The highest activity concentration of 210Pb was detected in Cortinarius armillatus L. (16.2 Bq kg-1 d.w.) and the lowest in Leccinum vulpinum L. (1.38 Bq kg-1 d.w.). The 210Po activity concentrations of the whole fruiting bodies ranged from 7.14 Bq kg-1 d.w. (Russula paludosa L.) to 1174 Bq kg-1 d.w. (L. vulpinum L.). In general, the highest activity concentrations of 210Po were recorded in boletes. The caps of mushrooms of the Boletaceae family showed higher activity concentrations of 210Po compared to the stipes. In most of the mushrooms analyzed, the activity concentrations of 210Po were higher than those of 210Pb. 210Po and 210Pb dominate the radiation doses received via ingestion of wild berries and mushrooms in northern Finland, while in southern Finland the ingested dose is dominated by 137Cs from the Chernobyl fallout.

  17. Cycling of 7Be and 210Pb in a high DOC, shallow, turbid estuary of south-east Texas

    The Sabine-Neches estuary is a shallow, turbid estuary in south-east Texas with high concentrations of dissolved organic carbon (DOC). The sediment inventory of 210Pb and 239,240Pu indicates that only a fraction of the particle-associated nuclides that reach the estuary were retained in the sediment. To better understand the cause for this low-sediment inventory of particle-reactive nuclides, 7Be and 210Pb concentrations have been measured in the dissolved and particulate phases, in addition to the DOC and suspended particle concentrations. The ratios of dissolved to particulate concentrations of 7Be and 210Pb were generally higher than in most other coastal waters. The dissolved residence times of 7Be and 210Pb (accounting for riverine input) varied between 0.6 and 9.6 days and 1.7 and 9.8 days, respectively. Distribution coefficients (Kd) ranged between 1500 and 87 100 cm3 g-1 for 7Be and 2600 and 37 000 cm3 g-1 for 210Pb. These Kds are lower than those reported for most coastal waters. There was no significant correlation between suspended particle concentration and Kd of either 7Be and 210Pb; this has been observed for many other particle-reactive nuclides, suggesting that particle is not the primary controlling variable for the removal of particle-reactive nuclides in these high DOC waters. The average particle residence time in this estuary is ∼ 2 days. The relatively low Kd values, longer dissolved residence times of 7Be and 210Pb, longer particle residence times and shorter hydraulic residence times compared to other coastal areas, result in only a partial removal of particle-reactive radionuclides in this estuary. (author)

  18. Migration of 226 Ra, 228 Ra, 210 Pb, U and Th from phosphogypsum

    The physico-chemical availability of radioactive elements (210 Pb, 226 Ra, 228 Ra, Th and U) in Brazilian phosphogypsum was investigated in a large scale leaching experiment carried out in lysimeters, using phosphogypsum samples (approximately 1.2 tons) from two phosphoric acid industries. Lysimeters were built using cylindrical concrete containers with 0.9 m inner diameter and 2 m depth. The bottom of the lysimeter was filled with a 10 cm layer of gravel covered with geomembrane sheet. Under this layer a pipe was designed to drain the percolated water. Three lysimeters were filled with phosphogypsum from each industry and a mixture of both. As percolated water comes exclusively from the rain, sample was collected daily when available. Samples were then pooled weekly, carefully prepared and submitted to radiochemical analysis. Radiochemical characterization of phosphogypsum and percolated water was performed by radiochemical separation followed by gross alpha and beta counting (226 Ra, 228 Ra and 210 Pb) and UV-Vis spectrophotometry with Arsenazo III (U and Th). This experiment was carried out from 12/01/1999 to 01/22/2001, with a precipitation of 2,732 mm. It was observed that approximately 40% (534 L) of the rain fall percolated through the lysimeter 1. The analysis of 22 samples of percolated water from lysimeter 1 showed mean radionuclides activities of 70±30 mBqL-1, 70±50 mBqL-1, 100±60 mBqL-1 and 110±55 mBqL-1 for U, 226 Ra, 228 Ra and 210 Pb, respectively. Thorium activities were below detection limit. (author)

  19. Radiochemical determination of 210 Pb and 226Ra in petroleum sludges and scales

    The oil extraction and production, both onshore and offshore, can generate different types of residues, such as sludge, that is deposited in the water/oil separators, valves and storage tanks and scales, which form i the inner surface of ducts and equipment. Analyses already carried out through gamma spectrometry indicated the existence of high radioisotope concentration. However, radionuclides emitting low-energy gamma-rays, such as 210 Pb, are hardly detected by that technique. Consequently, there is a need to test alternative techniques to determine this and other radionuclides from the 238 U series. This work, therefore, focuses on the radiochemical determination of the concentration of 210Pb, and 226 Ra in samples of sludge and scale from the oil processing stations of the UN-SEAL, a PETROBRAS unit responsible for the exploration and production of petroleum in Sergipe and Alagoas. The sludge and scale samples went through a preliminary process of extraction of oil, in order to separate the solid phase, where the largest fraction of the radioactivity is concentrated. After oil removal, the samples were digested using alkaline fusion as an option for dissolution. Finally, their activity concentration was determined for the samples of sludge and scales, using and alternative radiochemical method, which is based on ionic exchange. The activity concentration found for 210Pb varied from 1,14 to 507,3 kBq kg-1. The values for 226Ra were higher, varying from 4,36 to 3.445 kBq kg-1. The results for 226Ra were then compared with the ones found for the same samples of sludge and scales using gamma spectrometry. The results of the comparison confirm the efficiency of the methodology used int hi work, that is, radiochemical determination by means of ionic exchange. (author)

  20. The use of 210Pb and 137Cs in environmental studies

    The use of natural radioactivity in environmental studies has proven a very powerful tool to determine the dynamics of both natural and antrophogenic processes in our environment. The use of 14C in archaeology and past climate studies has led to many scientific discoveries (the shroud of Turin and Utze the ice-man from Austria are two examples). The use of the 238U-decay series is of at least equal value to studies in archaeology and of past climates. Some of the Isotopes studied supplement 14C (which is limited to 40,000 years) data and allow dating of samples formed up to 500,000 years ago (see McCullough, this book of abstracts, pages 19-23), others can be utilised to date very young sediments, which can't be dated by 14C.The so-called 210Pb dating method has been used over the past 3 decades to date recent sediment. The method uses the disequilibrium in the 238U decay chain, caused by the escape of the intermediate daughter 222Rn, a noble gas, from the earth's crust. In the atmosphere the 222Rn decays via short-lived daughter isotopes to 210Pb. This 210Pb with a very convenient half-life of 22,3 years decays to stable 206Pb. By measuring the surface activity of a sediment core and subsequent samples at regular intervals, a chronology for the sediment core can be established (relative to the surface). In addition to 210Pb dating one could analyse the samples for l37Cs to establish an independent chronology based on a pulse of radioactive Caesium. The pulse of 137Cs originates from the atmospheric atomic-bomb test of the early sixties. The maximum of Caesium activity found in a core should correspond to the height of the tests (approximately 1963 in the Northern hemisphere). A combination of the two dating methods often leads to more reliable results in the chronology. Another use of 137Cs is to test if the sediment has been subject to bio-turbation or other mixing. In the case of disturbance the proper pulse of Caesium would be smeared out and would not look

  1. Data base structure and Management for Automatic Calculation of 210Pb Dating Methods Applying Different Models

    The introduction of macros in try calculation sheets allows the automatic application of various dating models using unsupported ''210 Pb data from a data base. The calculation books the contain the models have been modified to permit the implementation of these macros. The Marine and Aquatic Radioecology group of CIEMAT (MARG) will be involved in new European Projects, thus new models have been developed. This report contains a detailed description of: a) the new implement macros b) the design of a dating Menu in the calculation sheet and c) organization and structure of the data base. (Author) 4 refs

  2. Sediment resuspension on the middle continental shelf adjacent to Sydney, Australia - evidence using 210Pb

    Full text: A regional survey of surficial sediments on the central NSW continental margin has established anthropogenic contributions of trace metals from the urban centres of Sydney, Newcastle and Wollongong. The anthropogenic contributions are discernible in the sediment fine fraction (210Pb and trace metals to determine long-term sedimentation rates and zones of sediment mixing due to resuspension. Muddy middle shelf sediments display a shallow surficial mixing zone, increasing in depth in sandy sediment. Sandy middle shelf sediments have therefore a greater resuspension potential during frequent storm events and are unlikely to act as long-term contaminant sinks

  3. Accumulation of 210Pb activity on particulate matter in LPG rail cars

    In Canada, liquefied natural gas is transported over large distances by rail cars with capacities of approx. 105. At least every 10 y, the gas vessels of these cars are tested hydrostatically. During this operation, about 10 L of fine ferric dust is found to have accumulated inside the vessels. The dust has been found to consist of flakes of about 200μ in size which has accumulated 210Pb and daughter activities. The specific activities have been measured for a composite sample by beta and alpha spectrometry and have been found to be similar to activities previously reported for the interior surfaces of valves and separators in natural gas processing plants. (author)

  4. The behavior of 210Pb and 7Be in the atmosphere in Nagasaki

    Nagasaki is located in the western end of Japan, and first receives aerosol factors in Japan from the Eurasian Continent such as Asian dusts and directly almost with no mixing of the domestic factors. Since this geographically situation of Nagasaki area, we have measured the aerosol size and the concentration of 210Pb and 7Be adhering to aerosol. Seasonal variation of these data was analyzed combined with some weather data, the rainfall and the wind direction. We present and discuss some result from the analysis. (author)

  5. 210Pb geochronology of stream sediments from the Guama river and Guajara bay, Belem - Amazon Region

    This study was able to date three sediment profiles collected at the mouth of the Amazon river using the 210Pb geochronology method. All sediment profiles were sliced into layers of 5 cm and each layer was analyzed for radionuclides by Gamma Spectrometry. The results obtained dated the sediments as far back as 65 years. In addition, the sedimentation rate was also determined. A subsequent interpretation of the results can provide information on pollutants present in the sediment layers and infer possible contamination patterns by operating industries and anthropogenic activities in the area of the Amazon Hydrographic Basin. (author)

  6. Sedimentary environment inferred from sedimentation rates by 210Pb and 137Cs and their inventories in Mutsu Bay, Japan

    Fourteen sediment cores were collected from Mutsu Bay, Aomori in Japan, and excess 210Pb and 137Cs were measured γ-spectrometrically. The spatial distributions of sedimentation rates by 210Pbex and 137Cs and their inventories were studied in order to clarify whole pictures about the sedimentary environment of Mutsu Bay. Excessively post-depositional mixing (up to a depth of 10-15 cm) of surface sediments by bioturbation was observed on the 210Pbex depth profiles in cores from the offshore areas. The sedimentation rates calculated varied in the wide range from 0.04 to 0.2 g/cm2/y. The sedimentation rates using 137Cs method could not be applied. Apart from the 210Pbex inventories from the nearshore area, the responding inventories (17-30 kBq/m2) from the offshore area were higher than the reported value of ca.15 kBq/m2 in the surrounding soils, indicating that the sediment focusing due to the inner current etc., to the deeper area from the surrounding nearshore area, affects the sediment accumulation in the offshore area. (author)

  7. Dynamics of bacterial communities in two unpolluted soils after spiking with phenanthrene: soil type specific and common responders

    Guo-Chun eDing

    2012-08-01

    Full Text Available Considering their key role for ecosystem processes, it is important to understand the response of microbial communities in unpolluted soils to pollution with polycyclic aromatic hydrocarbons (PAH. Phenanthrene, a model compound for PAH, was spiked to a Cambisol and a Luvisol soil. Total community DNA from phenanthrene-spiked and control soils collected on days 0, 21 and 63 were analyzed based on PCR-amplified 16S rRNA genefragments. Denaturing gradient gel electrophoresis (DGGE fingerprints of bacterial communities increasingly deviated with time between spiked and control soils. In taxon specific DGGE, significant responses of Alphaproteobacteria and Actinobacteria became only detectable after 63 days, while significant effects on Betaproteobacteria were detectable in both soils after 21 days. Comparison of the taxonomic distribution of bacteria in spiked and control soils on day 63 as revealed by pyrosequencing indicated soil type specific negative effects of phenanthrene on several taxa, many of them belonging to the Gamma-, Beta- or Deltaproteobacteria. Bacterial richness and evenness decreased in spiked soils. Despite the significant differences in the bacterial community structure between both soils on day 0, similar genera increased in relative abundance after PAH spiking, especially Sphingomonas and Polaromonas. However, this did not result in an increased overall similarity of the bacterial communities in both soils.

  8. Dynamics of bacterial communities in two unpolluted soils after spiking with phenanthrene: soil type specific and common responders

    Guo-ChunDing

    2012-01-01

    Considering their key role for ecosystem processes, it is important to understand the response of microbial communities in unpolluted soils to pollution with polycyclic aromatic hydrocarbons (PAH). Phenanthrene, a model compound for PAH, was spiked to a Cambisol and a Luvisol soil. Total community DNA from phenanthrene-spiked and control soils collected on days 0, 21 and 63 were analyzed based on PCR-amplified 16S rRNA genefragments. Denaturing gradient gel electrophoresis (DGGE) fingerprints...

  9. Dynamics of Bacterial Communities in Two Unpolluted Soils after Spiking with Phenanthrene: Soil Type Specific and Common Responders

    Ding, Guo-Chun; Heuer, Holger; Smalla, Kornelia

    2012-01-01

    Considering their key role for ecosystem processes, it is important to understand the response of microbial communities in unpolluted soils to pollution with polycyclic aromatic hydrocarbons (PAH). Phenanthrene, a model compound for PAH, was spiked to a Cambisol and a Luvisol soil. Total community DNA from phenanthrene-spiked and control soils collected on days 0, 21, and 63 were analyzed based on PCR-amplified 16S rRNA gene fragments. Denaturing gradient gel electrophoresis (DGGE) fingerprin...

  10. Air mass origins by back trajectory analysis for evaluating atmospheric 210Pb concentrations at Rokkasho, Aomori, Japan

    Atmospheric concentrations of 210Pb change with various factors such as meso-scale meteorological conditions. We have already reported the biweekly atmospheric 210Pb concentrations in Rokkasho, Japan for 5 years and found that they had clear seasonal variations: low concentrations in summer and high values in winter to spring. To study the reasons for the seasonal variations, the origins of the air mass flowing to Rokkasho were analyzed by 3-D backward air mass trajectory analysis. Routes of the calculated trajectories were classified into four regions: northeastern and southeastern Asian Continent, sea and other regions. The atmospheric 210Pb concentrations were well correlated with the frequency of the routes through the northeastern Asian Continent. A non-linear multiple regression analysis of the 210Pb concentrations and the relative frequencies of the four routes showed good fitting of the predicted values to the observed ones, and indicated that the atmospheric 210Pb concentrations in Rokkasho depended on the frequency of the air mass from the northeastern Asian Continent. (author)

  11. Analysis of 210 Pb and 137 Cs in diets of university students

    In this work, 210 P and 137 Cs were determined in the male students diets (age: 19-25) of Sao Paulo University, by gamma spectrometry. The sampling was made using the duplicate portion methodology, which consists in collecting duplicate portions of all food and beverage consumed during three days of a week. The levels obtained for 210 Pb in these samples varied from the Minimum Detectable Concentration (0.43 Bq.kg-1 ) to 1.68 Bq.kg-1 . For 137 Cs, the values ranged from the Minimum Detectable Concentration (0.17 Bq.kg-1 ) to 0.95 Bq.kg-1 . An estimate of the daily ingestion of those radionuclides was made according to the data obtained. The values varied from 78 to 309 mBq.d-1 for 210 Pb, and 53 to 157 mBq.d-1 , for 137 Cs, among the diets analyzed. The data obtained these diets agreed with the data obtained for other authors. (author)

  12. Sedimentation rate estimates in Sorsogon Bay, Philippines using 210Pb method

    Sorsogon Bay has experienced a long history of recurring harmful algal blooms over the past few years. In an attempt to establish a chronology of events in the sediment layer, lead-210 (210Pb) dating method has been utilized in estimating sedimentation rates from three selected areas along the bay. Based on the unsupported 210Pb data and by applying the Constant Initial Concentration (CIC) model, the calculated sedimentation rates were 0.8, 1.3 and 1.8 cm yr1 for sediment cores collected near the coastal areas of Castilla (SO-01), Sorsogon City (SO-07) and Cadacan River (SO-03), respectively. High sedimentation rates were measured in sediment cores believed to be affected from frequent volcanic ash releases and from areas near human settlement combined with intensive farming and agricultural activities. The collected sediments exhibited non-uniform down core values of dry bulk density and moisture content. This variation in measurements may indicate the general quality and composition of the sediment samples, i.e., amount of organic matter and grain size. The calculated sedimentation rates obtained provided an overview of the sedimentation processes and reflect the land use pattern around the bay which may help in understanding the history and distribution of materials and nutrient input relative to the occurrence of harmful algal bloom in the sediment columns. (author)

  13. Cascade ultrafiltering of 210Pb and 210Po in freshwater using a tangential flow filtering system

    A rapid method was developed using ultrafilters with a tangential flow filtering system for molecular size separation of naturally occurring 210Pb and 210Po in a freshwater sample. Generally, ultrafiltering of a large volume water sample for measuring the nuclides was too time consuming and not practical. The tangential flow filtering system made the filtering time short enough to adapt for in-situ ultrafiltering the large volume sample. In this method, a 20 liter water sample was at first passed through the 0.45 μm pore size membrane filter immediately after sample collection to obtain suspended particle matter [>0.45 μm particulate fraction (PRT)]. Two ultrafilters (Millipore Pellicon 2R) were used sequentially. The nuclides in the filtrate were separated into three fractions: high molecular mass (100 kDa-0.45μm; HMM), low molecular mass (10 k-100 kDa; LMM) and ionic (210Pb and 210Po in an oligotrophic lake, Lake Towada located in the northern area of Japan. (author)

  14. Allometric relationships of 210Po and 210Pb in mussels and their application to environmental monitoring

    Mussels from the Portuguese coast collected during several seasons of the year have shown 210Po and 210Pb body burdens (Bq mussel-1) that increased with mussels' body size but displayed significant decrease in radionuclide concentrations (Bq kg-1). For example, the increase of mussel size from 2.5 cm to 5.0 cm maximum shell length corresponded in average to a 50% decrease of 210Po activity concentration in soft tissues from 1065 Bq kg-1 (dw) to 540 Bq kg-1 (dw). A similar reduction in concentration was observed for 210Pb. The physiological condition of mussels, relating to fat and glycogen storage, had an effect on radionuclide concentrations, although the total body burden of radionuclide in mussels remained nearly constant throughout the year. These factors may play an important role in data interpretation for environmental monitoring programmes. Besides the mussel size and condition index, due to the inter-individual variation even inside narrow mussel size classes, the sample size, i.e., the number of specimens in one mussel sample is another key factor to be considered when obtaining environmentally representative radionuclide concentrations.

  15. 210Po and 210Pb concentration in drinking water of Bangalore and its surroundings

    Drinking water samples collected from different locations of Bangalore and its surrounding area were analysed for the activity concentrations of 210Po and 210Pb by employing radiochemical analysis. The measure concentration of 210Po varies from 0.46 to 36.46 mBq L-1 with a mean of 6.17 mBq L-1 and that of 210Pb ranges from 1.19 to 56.95 mBq L-1 with a mean of 13.98 mBq L-1. The activity concentrations of these radionuclides were found to be low at the place Kambasandra and high at Kalkere. The range and the mean value obtained in the present study are well within the guidance value of 100 mBq L-1 as prescribed by World Health Organization. From the measured concentrations of these radionuclides, the annual effective dose was calculated for different age groups: for babies (age below 1 y), children (age from 2 to 7 y) and adults (age from 17 y and above) using IAEA dose conversion factors and the prescribed water consumption rates. The total dose received is very much less than the ICRP recommended value of 1000 μ Sv y-1 for all age groups. (author)

  16. Hair and feathers as indicator of internal contamination of 210Po and 210Pb

    The activities of the NKS-B HAIRPOL project is summarised in this report. The objective was to investigate if hair and feathers were suitable matrices for the estimation of the intake of 210Po. Human hair from people of different sex and age was analysed for 210Po showing concentrations between 0.4 to 11 Bq/kg dry weight. Samples from horses, mane, fur and tail showed concentration from 6 to 17 Bq/kg with no significant difference between the different sample types. Musk ox from Greenland showed much higher concentrations since the animal has to graze a large surface. In fur the concentration was 260 Bq/kg. A considerable fraction of the total 210Po in this animal is contained in the hair. Also different organs were analysed and the highest concentration was found in kidney, 2 700 Bq/kg. The 210Pb concentration in hair was estimated to about 20 Bq/kg. Three different seabirds from Svalbard were analysed. Feathers from all three seabird species show increasing activity concentrations of 210Po and 210Pb from the base to the tip of the feather, but it was difficult to relate feather concentrations to muscle concentrations due to a number of complicating factors. (author)

  17. Hair and feathers as indicator of internal contamination of 210Po and 210Pb

    Holm, E. (ed.); Gwynn, J.; Zaborska, A.; Gaefvert, T. (Norwegian Radiation Protection Authority (Norway)); Roos, P. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Henricsson, F. (Lund Univ., Lund (Sweden))

    2010-03-15

    The activities of the NKS-B HAIRPOL project is summarised in this report. The objective was to investigate if hair and feathers were suitable matrices for the estimation of the intake of 210Po. Human hair from people of different sex and age was analysed for 210Po showing concentrations between 0.4 to 11 Bq/kg dry weight. Samples from horses, mane, fur and tail showed concentration from 6 to 17 Bq/kg with no significant difference between the different sample types. Musk ox from Greenland showed much higher concentrations since the animal has to graze a large surface. In fur the concentration was 260 Bq/kg. A considerable fraction of the total 210Po in this animal is contained in the hair. Also different organs were analysed and the highest concentration was found in kidney, 2 700 Bq/kg. The 210Pb concentration in hair was estimated to about 20 Bq/kg. Three different seabirds from Svalbard were analysed. Feathers from all three seabird species show increasing activity concentrations of 210Po and 210Pb from the base to the tip of the feather, but it was difficult to relate feather concentrations to muscle concentrations due to a number of complicating factors. (author)

  18. Effect of heavy metals on pH buffering capacity and solubility of Ca, Mg, K, and P in non-spiked and heavy metal-spiked soils.

    Najafi, Sarvenaz; Jalali, Mohsen

    2016-06-01

    In many parts of the world, soil acidification and heavy metal contamination has become a serious concern due to the adverse effects on chemical properties of soil and crop yield. The aim of this study was to investigate the effect of pH (in the range of 1 to 3 units above and below the native pH of soils) on calcium (Ca), magnesium (Mg), potassium (K), and phosphorus (P) solubility in non-spiked and heavy metal-spiked soil samples. Spiked samples were prepared by cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) as chloride salts and incubating soils for 40 days. The pH buffering capacity (pHBC) of each sample was determined by plotting the amount of H(+) or OH(-) added (mmol kg(-1)) versus the related pH value. The pHBC of soils ranged from 47.1 to 1302.5 mmol kg(-1) for non-spiked samples and from 45.0 to 1187.4 mmol kg(-1) for spiked soil samples. The pHBC values were higher in soil 2 (non-spiked and spiked) which had higher calcium carbonate content. The results indicated the presence of heavy metals in soils generally decreased the solution pH and pHBC values in spiked samples. In general, solubility of Ca, Mg, and K decreased with increasing equilibrium pH of non-spiked and spiked soil samples. In the case of P, increasing the pH to about 7, decreased the solubility in all soils but further increase of pH from 7, enhanced P solubility. The solubility trends and values for Ca, Mg, and K did not differed significantly in non-spiked and spiked samples. But in the case of P, a reduction in solubility was observed in heavy metal-spiked soils. The information obtained in this study can be useful to make better estimation of the effects of soil pollutants on anion and cation solubility from agricultural and environmental viewpoints. PMID:27168329

  19. Fractionation of Uranium Forms as Affected by Spiked Soil Treatment and Soil Type

    In a fractionation experiment Uranium forms were compared in two soil types (Mostorud and Elgabalelasfar soil). Also, the variation of U forms due to soil treatment (spiking) were studied. In case of Mostorud soil the initial U - fractions were 45.63 % as residual form, 20.69 % organically bound 16.36 % Mn and Fe oxides bound, 9.76% Carbonate form, 7.41 % exchangeable fractions and 0.15% water soluble fractions. These fractions varied significantly when the soil was spiked with 200 mg U/Kg soil to 46.88 %, 23.19 %, 9.97 %, 16.07 %, 3.79% and 0.10% for residual, organically, Mn- Fe oxide, carbonate, exchangeable and water soluble fractions respectively. These result showed significant reduction in U-ex fraction forms and Mn- Fe bound forms with significant increase in U- carbonate form due to U application. In case of Elgabalelasfar soil, the main U - fractions were 57.42% as residual form (relatively higher residual - U form in the clayey soil) 16.10 % organically bound, 13.78% Mn and Fe oxides bound, 7.22 % Carbonate form, 5.23 % exchangeable fractions and 0.25 % water soluble fractions The application of 200 mg U/Kg soil resulted in a significant changes in U - Fractions distribution as follows : 59.26 % , 11.27 % , 19.59 % , 6.84 % , 2.90 % and 0.14 % for residual , organic , Mn- Fe oxides , carbonate, exchangeable and water soluble fractions , respectively.

  20. The atmospheric depositional fluxes of 7Be, 210Pb and 210Po to Xiamen and Qingdao, China

    7Be (half life t1/2 = 54.3 d) is produced by the spallation of atmospheric oxygen and nitrogen with cosmic rays. 210Pb (t1/2= 22.3 a) in air is produced by decay from 222Rn (t1/2= 3.8d) which emanates into the atmosphere from the earth's surface. 210Po (t1/2= 138 days) in air is produced from the decay of 210Pb through 210Bi (t1/2=5.0 days). 7Be, 210Pb and 210Po is easily absorbed to aerosols and removed to land and ocean through precipitation and dry fallout. The atmospheric depositional fluxes of 7Be, 210Pb and 210Po to Xiamen and Qingdao were measured in this paper. The samples were collected with plastic vessels fixed on the top of the Oceanography Building of Xiamen University and the Environmental Engineering Building of Oceanography University of China in Qingdao of China. The sampling period is one month normally. The 7Be and 210Pb were measured using HPGe-γ spectrometer after concentration by Fe(OH)3 co-precipitation method, but the 210Po was counted with α spectrometer after the sample is digested and electroplated onto a silver planchet. From March to October 2004 at Xiamen, the depositional fluxes of 7Be varied from 0.58 to 2.78 Bq m-2 d-1 and the average is 1.99 Bq m-2 d-1, 210Pb varied from 0.24 to 0.86 Bq m-2 d-1, and the average is 0.60 Bq m-2 d-1; 210Po varied from 0.02 to 0.13 Bq m-2 d-1 and the average is 0.06 Bq m-2 d-1. The 7Be/210Pb activity ratio is between 0.67 and 5.53 and the average is 3.48. The flux of 7Be is lower in April, June and October; the flux of 210Pb in June is lower than other periods. The 7Be/210Pb activity ratio is -the highest in may while it is the lowest in April. From May to November 2004 at Qingdao, the depositional fluxes of 7Be varied between 1.54 and 2.60 Bq m-2 d-1 with the average 2.08 Bq m-2 d-1; 210Pb varied between 0.33 and 0.73 Bq m-2 d-1 with the average 0.55 Bq m-2 d-1; 210Po varied between 0.03 and 0.19 Bq m-2 d-1 with the average 0.08 Bq m-2 d-1. The 7Be/210Pb activity ratio is between 2.81 and 6.62 and

  1. 210Pb balance and implications for particle transport on the continental shelf, U.S. Middle Atlantic Bight

    Bacon, M.P.; Belastock, Rebecca A.; Bothner, Michael H.

    1994-01-01

    Supply of 210Pb to the continental shelf off the northeastern United States is dominated by the deposition from the atmosphere, the rate of which is reliably known from previously published work. Excess 210Pb inventories in the shelf sediments show accumulations that are nearly in balance with the supply, even in areas of relict sands where it is believed that no net accumulation of sediment presently occurs. The 210Pb distributions in shelf and slope water indicate that the two-way fluid exchange at the shelf-slope front and the net transport in the alongshore flow make comparatively small contributions to the shelf 210Pb budget. The near balance between supply and decay of 210Pb on the shelf implies a limit to the particle export flux. It is concluded that the export of particulate organic carbon does not exceed 60 g m−2 y−1 (∼25% of primary production) and is probably lower. The hypothesis is advanced that fine particulate matter introduced to the continental shelf is detained in its transit of the shelf because of bioturbational trapping in the sediment due to benthic animals. Distributions of 210Pb in suspended particulate matter and in the fine fraction of shelf sediments suggest that the average fine particle must undergo several cycles of deposition-bioturbation-resuspension-redeposition and requires a number of decades for its transit and ultimate export from the shelf. Thus, only the most refractory organic matter is likely to be exported.

  2. Distribution and biokinetic analysis of {sup 210}Pb and {sup 210}Po in poultry due to ingestion of dicalcium phosphate

    Casacuberta, N., E-mail: Nuria.Casacuberta@uab.es [Departament de Fisica and Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Traversa, F.L. [Departament d' Electronica, Escola Tecnica Superior d' Enginyeria, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Masque, P.; Garcia-Orellana, J. [Departament de Fisica and Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Anguita, M.; Gasa, J. [Departament de Ciencia Animal i dels Aliments, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain); Garcia-Tenorio, R. [Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012 Sevilla (Spain)

    2010-09-15

    Dicalcium phosphate (DCP) is used as a calcium supplement for food producing animals (i.e., cattle, poultry and pig). When DCP is produced via wet acid digestion of the phosphate rock and depending on the acid used in the industrial process, the final product can result in enhanced {sup 210}Pb and {sup 210}Po specific activities ({approx} 2000 Bq.kg{sup -1}). Both {sup 210}Pb and {sup 210}Po are of great interest because their contribution to the dose received by ingestion is potentially large. The aims of this work are to examine the accumulation of {sup 210}Pb and {sup 210}Po in chicken tissues during the first 42 days of life and to build a suitable single-compartment biokinetic model to understand the behavior of both radionuclides within the entire animal using the experimental results. Three commercial corn-soybean-based diets containing different amounts and sources of DCP were fed to broilers during a period of 42 days. The results show that diets containing enhanced concentrations of {sup 210}Pb and {sup 210}Po lead to larger specific accumulation in broiler tissues compared to the blank diet. Radionuclides do not accumulate homogeneously within the animal body: {sup 210}Pb follows the calcium pathways to some extent and accumulates largely in bones, while {sup 210}Po accumulates to a large extent in liver and kidneys. However, the total amount of radionuclide accumulation in tissues is small compared to the amounts excreted in feces. The single-compartment non-linear biokinetic model proposed here for {sup 210}Pb and {sup 210}Po in the whole animal takes into account the size evolution and is self-consistent in that no fitting parameterization of intake and excretions rates is required.

  3. Transfer of 226Ra, 228Ra, 210Pb and 210Po in aquatic organisms and food chain

    Objective: To find out the transfer regularities of 226Ra, 228Ra, 210Pb and 210Po, which are natural radionuclides in the aquatic organisms and food chain. Methods: Large amount of breed of representative aquatic products and their living waters and sediments were collected and treated according to routine experimental procedures. The contents of 226Ra, 228Ra, 210Pb and 210Po were detected in each sample. Measured data were analyzed statistically and pairwise comparisons were made to determine the differences between groups. Results: 226Ra, 228Ra and 210Pb were mainly deposited in the bones (or shells), their concentration factors (CF) ranged from 102 to 103; the CF ranged only from 100 to 102 in the flesh. 210Po was mainly deposited in the soft tissues, CF ranged from 102 to 104; especially in the stomachs and intestines of fishes, the value reached 104. The cooking process did not impinge significantly on the transfer of 226Ra, 228Ra and 210Pb in the food chain (P>0.05), but did significantly influence the transfer of 210Po, especially in the freshwater fishes and shrimps. Paired comparison test of the activities between raw flesh and cooked flesh showed very significant difference (P226Ra, 228Ra, 210Pb and 210Po. Even though the bones (or shells) of aquatic organisms contained relatively higher levels of 226Ra, 228Ra and 210Pb, the cooking process does not significantly increase the radioactive contents in the foodstuffs. However, the cooking process does significantly influence the transfer of 210Po. It does significantly increase the content of 210Po in foodstuffs

  4. Validation of an extraction chromatographic method with SrResin for determination of 210Pb in various matrices

    A radiochemical method for the determination of 210Pb in various types of samples was validated. An extraction chromatographic material Eichrom SrResin(R) was used for Pb separation. From the resin, Pb was eluted with 6 M HCl. The method was tested for water, inorganic and organic matrices. As a main result of the study, activity concentrations of 210Pb in 19 food samples of the main Czech food-basket items were determined. Results ranged from 0.03 ± 0.01 Bq kg-1 to 1.54 ± 0.40 Bq kg-1, fresh mass. (author)

  5. Separation of 210Pb, 210Bi and 210Po by ion exchange and their Iiquid scintillation standardization

    We applied the CIEMAT/NIST method and alpha/beta discrimination to ''210Pb samples in equilibrium with its daughters, by preparing homogeneous and gel samples. The stability of samples was tested in different available cocktails, HiSafe''TM II, HiSafe''TM III, Ultima-Gold''TM, Ultima-Gold''TM XR, Ultima-Gold''TM AB, Insta-Gel''R and e Insta-Gel''R lI. Also we analyzed the disequilibrium of the radioactive chain 210Pb+210Bi+210Po, achieving an excellent agreement between the results of the spectrum unfolding method and the experimental values. (Author) 13 refs

  6. Separation of 210 Pb, 210 Bi and 210 Po by ion exchange and their liquid scintillation standardization

    We applied the CIEMAT/NIST method and alpha/beta discrimination to ''210 Pb samples in equilibrium with its daughters, by preparing homogeneous and gel samples. The stability of samples was tested in different available cocktails, HiSafe''tm II, HiSafe''tmIII, Ultima-Gold''tm, Ultima-Gold''tmXR, Ultima-Gold''tmAB, Insta-Gel and e Insta-Gel II. Also we analyzed the disequilibrium of the radioactive chain ''210Pb+''210Bi+''210Po, achieving and excellent agreement between the results of the spectrum unfolding method and the experimental values. (Author) 13 refs

  7. Geochronology of recent sediments from the Cariaco Trench (Venezuela) by Alpha Spectrometry of 210Pb (210Po)

    210Pb concentration in marine sediments of the Cariaco Trench (North-East of Venezuela) was measured through the analysis of 210Po alpha emissions, which can be assumed to be in secular equilibrium with 210Pb. The analysed sediment core has a length of 1.9 m. The results allowed to apply the CF:CS dating model (Constant Flux and Constant Supply). The sedimentation rate was estimated to be 0.25 cm/y. As far as we know this is the first α- dating carried out in the country, performed with an alpha spectrometer recently funded by the IAEA.

  8. Transfer of 210Po, 210Pb and 238U from some medicinal plants to their essential oils

    Essential oils were extracted from 35 medicinal plants used by Syrians, organic compounds were determined in these oils and concentrations of 210Po 210Pb and 238U were determined in the original plants and in the essential oils. The results showed that the highest activity concentrations of 210Po and 210Pb were found in leaves with large surfaces and in Sage were as high as 73.5 Bq kg−1 and 73.2 Bq kg−1, respectively. The activity concentration of 238U was as high as 4.26 Bq kg−1 in Aloe. On the other hand, activity concentrations of 210Po ranged between 0.2 and 71.1 Bq kg−1 in extracted essential oils for Rosemary and False yellowhead, respectively. The activity concentration of 210Pb reached 63.7 Bq kg−1 in Aloe oil. The activity concentrations of 238U were very low in all extracted oils; the highest value was 0.31 Bq kg−1 in peel of Orange oil. The transfer of 210Po and 210Pb from plant to its oil was the highest for Eugenia; 7.1% and 5.5% for 210Po and 210Pb, respectively. A linear relationship was found between the transfer factor of radionuclides from plant to its essential oil and the chemical content of this oil. - Highlights: • Natural radionuclides 210Po, 210Pb and 238U were determined in 35 medicinal plants and their essential oils. • The highest activity concentration of 210Po and 210Pb were 73.5 Bq kg−1 and 73.2 Bq kg−1 in Sage, respectively. • The transfer of 210Po and 210Pb from Eugenia plant to its oil was the highest amongst other plants. • The data obtained in this study can be considered the first reported data for medicinal plants and their oils in Syria

  9. Distribution of 210Pb activity concentrations in marine surface sediments within East Coast Peninsula Malaysia Exclusive Economic Zone (EEZ)

    A sampling expedition into the East Coast Peninsula Malaysia Exclusive Economic Zone (EEZ) was carried in June 2008. Marine surface sediment samples were taken and the activity concentrations of 210Pb have been determined. Its distribution was plotted and the findings show that the activity concentrations decline from north to south. On the other hand, the activity concentrations are increasing from west to east right to the edge of the EEZ. The highest activity concentrations were found to be near offshore oil platforms. The 210Pb activity concentrations were found to be in the range of 18.3 - 123.1 Bq/ kg. (author)

  10. 210Pb and 210Po concentrations in the Venice lagoon ecosystem (Italy) and the potential radiological impact to the local public and environment

    In order to evaluate the possible radiological impact to the local public and environment from a phosphogypsum stockpile, 210Po and 210Pb concentrations in river water, lagoon water, suspended matter, superficial sediment, algae and bivalves samples collected in Venice lagoon area have been investigated. The results show that the mean 210Po and 210Pb concentrations in river water are 1.42 ± 0.36 mBq x l-1 and 1.46 ± 0.39 mBq x l-1 with a mean 210Po/210Pb ratio of 0.98 ± 0.17 and about 60% of them are associated with the particulate; 210Po and 210Pb contribution from the phosphogypsum stockpile to the river water is negligible. Higher 210Po (2.61-5.67 mBq x l-1) and 210Pb (1.31-3.62 mBq x l-1) concentrations in the lagoon waters have been observed if compared with the literature values. About 60% of 210Po and 210Pb are found in the soluble form with a mean 210Po/210Pb ratio of 1.79 ± 1.47. 210Po and 210Pb concentrations in 28 out 37 sediment samples ranged from 26 to 45 Bq x kg-1 (dry weight), only 9 sediments with 210Po and 210Pb concentrations greater than 45 Bq x kg-1 are found and most of them are located 1-4 km near the phosphogypsum stockpile. The elevated 210Po and 210Pb concentrations in the sediments may be due to the contamination from the phosphogypsum stockpile. The mean 210Po/210Pb ratio (0.986 ± 0.049) in the sediments shows that 210Po and 210Pb exist in nearly secular equilibrium. 210Po and 210Pb concentrations in algae vary with different species. The mean 210Po and 210Pb concentrations in Gracilaria compress and Ulva laetevirens which show a similar behavior, are 3.18 ± 1.23 Bq x kg-1 and 2.42 ± 1.26 Bq x kg-1 (fresh weight), respectively, with a mean 210Po/210Pb ratio of 1.45 ± 0.34. The mean concentration factors with respect to the filtered water are 1096 ± 424 for 210Po and 1299 ± 680 for 210Pb. The mean 210Po and 210Pb concentrations in the soft part of Mytilus edulis are 23.2 ± 9.7 Bq x kg-1 and 0.537 ± 0.203 Bq x kg-1 (fresh

  11. Using 137Cs and 210Pb to assess the sediment sources in a dam reservoir catchment on the loess plateau, China

    As the part of integrated studies of soil erosion and sedimentation within the same reservoir catchment, 'Sedimentation Assessment Studies' supported by IAEA, the primary scientific objective is to determine the source types of sediments reaching the reservoir and their relative contribution of different spatial locations to dam reservoir. This study addresses the need to quantify and link dam reservoir sedimentation, land use and different landscape locations using the 137Cs and 210Pb techniques within a GIS frame. A brief description of the basis for the site selection, sampling strategy, and the first results on the spatial distributions of 137Cs content and the possible sources of sediment and the relative contributions of these potential sources within the Yangjuangou dam reservoir catchment, Loess Plateau are provided. (3 figs., 4 tabs.)

  12. Radiochemical analysis of Ra, 210Po, 210Pb, U and Th

    Full text: The analysis of isotopes of uranium, thorium, radium, 210Po and 210Pb is of great importance in fields where these isotopes are used as tracers or where dosimetric aspects are considered. Because of the emission of alpha, beta and gamma radiation from several of the isotopes a combined measurement strategy is often preferred (eg beta counting of 234Th followed by alpha spectrometry of 228,230,232Th). Also, due to their position in the natural decay chains it is sometimes an advantage to measure the concentration of the daughter products than the mother isotope itself (eg. 222Rn+daughters instead of analysing 226Ra directly). The presentation gives an overview of analytical techniques useful for separating the isotopes in a sequential manner from each other. (author)

  13. Normal dietary levels of 226Ra, 228Ra, 210Pb, and 210Po for man

    A review of the literature and the results of some recent measurements were presented on the levels in man's diet of the naturally-occurring radionuclides 226Ra, 228Ra, 210Pb, and 210Po. The mean intakes for standard U.S. diets for these nuclides are tabulated. Intakes in other countries are similar to those in the U.S., but in localized populations the 226Ra intake may be 8 or more pCi/day. The contents of 226Ra in diets chosen by individuals ranged from 0.4 to 7 pCi/day. The few data on 228Ra show intake of this nuclide to be about 80% that of 226Ra, except in monazite areas where intakes of up to 160 pCi/day 228Ra are reported, which may be 50 to 100 times that of 226Ra. Drinking water contributes less than 5% of the daily intake, except in special areas

  14. Trace element dating by 210Pb: Application to an estuarine lagoon

    The Lagoa Olho D'Agua (Pernambuco, Brazil), is a 3.75 km2 lagoon which receives freshwater from both the Atlantic Ocean and Jaboatao River. The lagoon is under severe degradation process caused by pollutants released from industrial facilities and by the discharge of untreated domestic sewage. This contamination can be traced by analyzing sediments, which are the ultimate sink of pollutants that are derived from anthropogenic activities. The 210Pb dating method is the principal technique for characterizing sediments on a time scale spanning over the last 100-150 years. The objective of this study was to trace the time evolution of metal contaminants in sediments and its correlation with the industrial history of the area

  15. Determination of 210Pb, 210Bi and 210Po in natural drinking water

    A new method for the radioanalytical determination of the 222Rn progenies 210Pb, 210Bi and 210Po will be presented, which has been improved for analyses of water samples from different regions in Austria. 1-2 liter samples were taken in polyethylene bottles prefilled with conc. HNO3 to obtain 0.2M acidic solutions, thus avoiding adsorption effects. After adding 1.6 mg of inactive lead carrier, the water sample was evaporated to dryness, converted to the chloride form and dissolved in 1M HCl. From this solution (pH ∼ 1.5) sulfide precipitation was carried out using Na2S (1M). The precipitate was dissolved in HNO3, fumed with HCl and transferred into a phosphate system, which is necessary for extraction of 210Bi and 210Po with Polex TM, a liquid scintillation cocktail suitable for α/β-measurements using pulse shape analysis. Lead-210 was determined via ingrown 210Bi by a second extraction after ∼ 2 weeks. The radiochemical yield of the whole procedure was > 90% determined via lead recovery with AAS. Minimum detectable activities of 0.4 and 1.0 mBq x l-1 could be achieved for 210Po and 210Bi (210Pb), respectively. Results ranged from 1.5-20 mBq x l-1 and more in waters with extremely high 222Rn concentrations. Radon decay during the period between sampling and analysis plays an important role and strongly influences the results. (author)

  16. Phytotoxicity of trace metals in spiked and field-contaminated soils: Linking soil-extractable metals with toxicity.

    Hamels, Fanny; Malevé, Jasmina; Sonnet, Philippe; Kleja, Dan Berggren; Smolders, Erik

    2014-11-01

    Soil tests have been widely developed to predict trace metal uptake by plants. The prediction of metal toxicity, however, has rarely been tested. The present study was set up to compare 8 established soil tests for diagnosing phytotoxicity in contaminated soils. Nine soils contaminated with Zn or Cu by metal mining, smelting, or processing were collected. Uncontaminated reference soils with similar soil properties were sampled, and series of increasing contamination were created by mixing each with the corresponding soil. In addition, each reference soil was spiked with either ZnCl2 or CuCl2 at several concentrations. Total metal toxicity to barley seedling growth in the field-contaminated soils was up to 30 times lower than that in corresponding spiked soils. Total metal (aqua regia-soluble) toxicity thresholds of 50% effective concentrations (EC50) varied by factors up to 260 (Zn) or 6 (Cu) among soils. For Zn, variations in EC50 thresholds decreased as aqua regia > 0.43 M HNO3  > 0.05 M ethylenediamine tetraacetic acid (EDTA) > 1 M NH4 NO3  > cobaltihexamine > diffusive gradients in thin films (DGT) > 0.001 M CaCl2 , suggesting that the last extraction is the most robust phytotoxicity index for Zn. The EDTA extraction was the most robust for Cu-contaminated soils. The isotopically exchangeable fraction of the total soil metal in the field-contaminated soils markedly explained the lower toxicity compared with spiked soils. The isotope exchange method can be used to translate soil metal limits derived from soils spiked with metal salts to site-specific soil metal limits. PMID:25053440

  17. Determination of the latest sediment accumulation rates and pattern by performing 210Pb models and 137Cs technique in the Lake Bafa, Mugla, Turkey

    The sediment chronology was determined using Lead-210 (210Pb) and Cesium-137 (137Cs) dating method. Profile distributions of Polonium-210 (210Po) and 210Pb were evaluated with regarding to sediment porosity, core location, bottom currents and prevalent winds. Max. 210Po and 210Pb activity concentrations are found as 193.83 ± 4.43 and 187.84 ± 4.84 Bq kg-1 respectively. According to vertical radionuclide (210Po/210Pb) ratios, sediments especially in east part of the lake are rich with respect to the fecal pellets. Residence time of the 210Pb is calculated as 1.9 months in the lake. Average sedimentation rate (0.359 ± 0.012 cm year-1) in central area is higher than the near shore (0.137 ± 0.006 cm year-1) one in Lake Bafa. (author)

  18. An assessment of 210Pb and 210Po in terrestrial foodstuffs from regions of England and Wales

    Based on data for nationally available foodstuffs, naturally occurring 210Pb and 210Po contribute significantly to the UK radiation dose from dietary intake. To provide a more complete overview of radiological implications to the public, samples of offal, cereal, fruit, root and green vegetables were collected from 11 sites, including regions of potential 210Pb and 210Po enhancement. Considerable variability was evident in levels of 210Pb and 210Po from all sites and in all food types investigated. Higher concentrations were typically found in offal and cereals. Lowest concentrations were generally found in root vegetables. Between sites, the only evidence of elevated concentrations of 210Po occurred at Helston (210Po 3.0 Bq kg-1 in bovine liver, no other offal sample exceeding 0.8 Bq kg-1), and Holyhead 210Po 0.4 Bq kg-1 in blackberries, no other fruit sample exceeding 0.1 Bq kg-1). Other foodstuffs from these sites did not show similar enhanced levels of 210Po. The maximum dose arising from consumption of 210Pb and 210Po in foods surveyed in this study is estimated to be around 120 μSv year-1 to adults. This compares with an estimated UK average consumption dose from all nuclides and foodstuffs of 300 μSv year-1 (broad range 100-1000 μSv year-1). (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  19. Assessment Activity of 210Po and 210Pb in the Edible Tissues of Cultured Seabass (Lates calcariferat Peninsular Malaysia

    Noorliza Zakaria

    2013-01-01

    Full Text Available Analysis levels of 210Po and 210Pb were determined in the edible tissue of sea bass (Lates calcarifer from 14 cages in the west and east coast Peninsular of Malaysia. The concentrations level in fish were found varies from 1.35 ± 0.22 to 6.20 ± 0.99 Bq/kg dry weight210Po and 3.30 ± 2.69 to 51.71 ± 19.26 Bq/kg dry weight 210Pb. The level of this radionuclide was much related to the anthropogenic activities at the sampling locations neighbouring area, differences in metabolisms of fish and food intake pattern for each cage. Then the calculated daily intake value due to fish consumption was to be 7.69 mBq/d/person210Po and 35.90 mBq/d/person210Pb, which lower than those reported in others countries. In addition, the collective doses of210Po and210Pb were estimated to be 0.001mSv/year and 0.009 mSv/year, respectively. This suggests that the dose received by Malaysian due to consumption of fish is rather small, and did not deteriorate human’s health and safe for consumption.

  20. Determination of 210Pb and 212Pb in water and their radiological impact to the public via drinking water

    A sensitive and accurate method for determining ultra low-level 210Pb and 212Pb in water samples through double measurements was developed. Pb was pre-concentrated as hydroxides, separated from alkaline earth elements as PbS precipitate, purified by an anion exchange resin chromatography column, precipitated as PbSO4 for source preparation and counted by a low background β-counter. The procedure was checked with IAEA reference materials, and the results agreed well with the recommended values. The minimum detectable activity was 0.062 mBq·L-1 for 210Pb and 0.053 mBq·L-1 for 212Pb with a 48 L water sample. Seventeen drinking water samples were analyzed,with a Pb recovery of 88.8±5.5%, and the typical activity concentrations were 0.191-15.1 mBq·L-1 for 210Pb and of 1.12-5.77 mBq·L-1 for 212Pb. The estimated committed effective doses to adult members of the public in Italy due to intake of 210Pb and 212Pb in drinking water were 0.096-7.59 μSv·a-1 and 0.005-0.025 μSv·a-1, respectively. (authors)

  1. U/Th ratios, 210Pb activity and geochemical variations in a coastal sediment core off Ratnagiri

    Subsection of a sediment core of 1m length collected from a water depth of 45 m off Ratnagiri, Maharashtra were analysed for U/Th isotopes as well as 210Pb activity by alpha spectrometry and few metals (Al, Fe, Mn and As) by Atomic absorption spectrometry respectively. The clay sedimentation rate of 2.1 mm/y is estimated from excess 210Pb method. The assessed 210Pb inventory of 40 dpm/cm2 in the sediment core is in balance with that expected from the overhead water column 210Pb precipitation from atmospheric fallout. Subsurface sediment aluminum content ranges from 5.2 to 7.5 % which clearly shows clayey nature of sediment. As and Mn as well as As/Al and Mn/Al show relatively lower values in upper 10 cm segment suggesting a low oxygenated bottom waters, which is supported by high values of uranium (2.4 to 5.5 ppm) in the sediment. Further evidence of low oxygenated environment comes from high U/Th weight ratios (0.3 to 1.39) in the core compared to the earth's crustal ratio of 0.25. This site therefore seems to act as a sink for uranium isotopes. (author)

  2. 210Pb and 137Cs measurements in the Circum Bohai Sea coastal region: sedimentation rates and implications

    Fu WANG; Hong WANG; Jianfen LI; Yandong PEI; Changfu FAN; Lizhu TIAN; Zhiwen SHANG; Meiyu SONG; Yan GENG

    2008-01-01

    The representative 210Pb and 137Cs age-depth profiles were selected from more than 100 sites in the Circum Bohai Sea (CBS)coastal region to examine the sedimentation rates and associated environmental changes.There are three unique 210Pbexc distribution patterns:1)ideal-decaying type,representing relatively constant sediment supply and quieter environmental setting;2)wiggling type,but with approximately equivalent amplitude,representing coarser sediments and associated stronger flow current environment;and 3) episodic-eventinfluencing type,each representing typhoon storm-influenced depositional environment.Our results also show that there is a lower sedimentation rate(ca.0.1 cm/a)in the coastal lowlands,a higher sedimentation rate(ca.0.53 cm/a)in the intertidal flat and an intermediate rate of ca.0.58 cm/a in the subtidal zone near the Huanghua Harbor.The interbedded silt layer occurring in the core sediment reveals lower 210Pb activities,indicating a discontinuous sedimentation mostly due to typhoon events which dwarfs against 210Pb and 137Cs applicability.Overall,the 210Pb and 137Cs measurements of the present study provide physical insight into the evaluation of the coastal-marine ecological environment and associated management.

  3. Polonium ({sup 210}Po) and lead ({sup 210}Pb) in marine organisms and their transfer in marine food chains

    Carvalho, Fernando P., E-mail: carvalho@itn.p [Instituto Tecnologico e Nuclear, Departamento de Proteccao Radiologica e Seguranca Nuclear, E.N. 10, 2686-953 Sacavem (Portugal)

    2011-05-15

    The determination of {sup 210}Po and {sup 210}Pb was performed in marine organisms from the seashore to abyssal depths, encompassing a plethora of species from the microscopic plankton to the sperm whale. Concentrations of those radionuclides ranged from low values of about 5 x 10{sup -1} Bq kg{sup -1} (wet wt.) in jellyfish, to very high values of about of 3 x 10{sup 4} Bq kg{sup -1} (wet wt.) in the gut walls of sardines, with a common pattern of {sup 210}Po > {sup 210}Pb.These radionuclides are primarily absorbed from water and concentrated by phyto- and microzooplankton, and then are transferred to the next trophic level along marine food chains. Investigation in epipelagic, mesopelagic, bathypelagic and abyssobenthic organisms revealed that {sup 210}Po is transferred in the marine food webs with transfer factors ranging from 0.1 to 0.7, and numerically similar to those of the energy transfer in the marine food chains. As {sup 210}Po preferentially binds to amino acids and proteins, its transfer in food chains likely traces protein transfer and, thus, {sup 210}Po transfer factors are similar to ecotrophic coefficients. {sup 210}Pb is transferred less efficiently in marine food chains and this contributes to increased {sup 210}Po:{sup 210}Pb activity ratios in some trophic levels.

  4. Correlation of /sup 210/Po and /sup 210/Pb enrichments in the sea-surface microlayer with neuston biomass

    Heyroud, M.; Cherry, R.D. (International Laboratory of Marine Radioactivity, Musee Oceanographique (Monaco))

    1983-01-01

    Samples of surface microlayer, bulk seawater from 20 cm depth and neustonic organisms inhabiting the top 5 cm of the sea, were collected at regular intervals over a period of 17 months at a site 3 km off Monaco and analysed for naturally occurring radionuclides /sup 210/Po and /sup 210/Pb. Enrichment of /sup 210/Po in the microlayer compared with bulk seawater was observed, and found to be correlated significantly with the neuston biomass per unit volume. Enrichment of /sup 210/Pb in the microlayer was also observed, but only under higher neuston biomass conditions. The /sup 210/Po: /sup 210/Pb ratio was always higher in the microlayer than in bulk seawater. Additional information was obtained from /sup 210/Po measurements made on the bulk seawater in which the neuston had been collected and in which it had stood for periods of 2 to 4 h. These showed the neuston lost /sup 210/Po to the water at a rate of about 1 pCi g/sup -1/ dry biomass h/sup -1/. A significant flux of /sup 210/Po from bulk seawater to the surface microlayer, and thence possibly to the atmosphere, is estimated. This flux will vary seasonally with the planktonic biomass. Under high biomass conditions a similar flux for /sup 210/Pb may also be significant.

  5. The effect of air mass origin on the ambient concentrations of /sup 7/Be and /sup 210/Pb in Islamabad

    The concentration of radionuclides /sup 210/Pb and /sup 7/Be, having half lives of 22.3 years and 53.29 days, respectively, in the surface air samples of Islamabad (33.38 N, 73.10 E and Altitude approx. 536 m asl.) were measured. The non-destructive technique of gamma-spectrometry, with a high purity germanium HPGe detector, was employed for the analysis of all samples. The annual average concentrations of /sup 210/Pb and /sup 7/Be in the surface air samples were determined as 0.284 +- 0.15 and 3.171 +- 1.14 mBq m/sup -3/, respectively. Our results have shown a seasonal variation of the concentration of /sup 7/Be in air samples with high values for the spring season. High concentrations for /sup 210/Pb were obtained when air masses originated from plain areas of Pothohar region, located in the South-West, West and North West of Islamabad. Statistics of /sup 210/Pb and /sup 7/Be-laden aerosols in the environment of Islamabad has been shown. Our values show a nice agreement with the relevant reported results. (Orig./A.B.)

  6. Studies on the distribution of 210Po and 210Pb in the ecosystem of Point Calimere Coast (Palk Strait), India

    A systematic study on the natural radionuclides such as 210Po and 210Pb in the environmental matrices of Point Calimere ecosystem has been undertaken to establish a baseline data on the radiation profile of Point Calimere environment. The environmental samples such as water, sediment and biota (seaweeds, crustaceans, molluscs and fish) have been subjected to analyses. It has been observed that the concentration of 210Po and 210Pb in the water samples of Point Calimere to be 0.5 mBq/l and 1.3 mBq/l, respectively. The soft tissues of the organisms accumulated higher 210Po content while shells and bones contained more 210Pb. The bivalve molluscs Meretrix casta have been identified to accumulate higher concentration of 210Po suggesting that they could serve as bio-indicator of radionuclides like 210Po in the Point Calimere ecosystem. The concentration factor of 210Po for the biotic components ranged from ∼103 to 106 while for 210Pb it ranged from ∼103 to 105

  7. Analysis of sup(210)Pb in sediment trap samples and sediments from the northern Arabian Sea: Evidence for boundary scavenging

    Borole, D.V.

    PboninorganicphasesconsistingmostlyofFe– Mnoxides.Incidentally,thetimingoftwoMnflux peaks matches with the timing of 210 Pb flux peaks in the present study. The evidence to suggest that MnO 2 flux peaks during mid-year has been provided by Balakrish- nan Nair et al. (1999). Two reasons...

  8. Comparison of degradation between indigenous and spiked bisphenol A and triclosan in a biosolids amended soil

    This study compared the degradation of indigenous bisphenol A (BPA) and triclosan (TCS) in a biosolids-amended soil, to the degradation of spiked labelled surrogates of the same compounds (BPA-d16 and TCS-13C12). The aim was to determine if spiking experiments accurately predict the degradation of compounds in biosolids-amended soils using two different types of biosolids, a centrifuge dried biosolids (CDB) and a lagoon dried biosolids (LDB). The rate of degradation of the compounds was examined and the results indicated that there were considerable differences between the indigenous and spiked compounds. These differences were more marked for BPA, for which the indigenous compound was detectable throughout the study, whereas the spiked compound decreased to below the detection limit prior to the study completion. The rate of degradation for the indigenous BPA was approximately 5-times slower than that of the spiked BPA-d16. The indigenous and spiked TCS were both detectable throughout the study, however, the shape of the degradation curves varied considerably, particularly in the CDB treatment. These findings show that spiking experiments may not be suitable to predict the degradation and persistence of organic compounds following land application of biosolids. - Highlights: ► Degradation of indigenous and spiked compounds from biosolids were compared. ► Differences were observed for both the rate and pattern of degradation. ► Spiked bisphenol A entirely degraded however the indigenous compound remained. ► TCS was detectable during the experiment however the degradation patterns varied. ► Spiking experiments may not be suitable to predict degradation of organic compounds

  9. Comparison of degradation between indigenous and spiked bisphenol A and triclosan in a biosolids amended soil

    Langdon, Kate A., E-mail: Kate.Langdon@csiro.au [School of Agriculture, Food and Wine and Waite Research Institute, University of Adelaide, South Australia, 5005, Adelaide (Australia); Water for a Healthy Country Research Flagship, Commonwealth Scientific and Industrial Research Organisation (CSIRO), PMB 2, Glen Osmond, South Australia, 5064, Adelaide (Australia); Warne, Michael StJ. [Water for a Healthy Country Research Flagship, Commonwealth Scientific and Industrial Research Organisation (CSIRO), PMB 2, Glen Osmond, South Australia, 5064, Adelaide (Australia); Smernik, Ronald J. [School of Agriculture, Food and Wine and Waite Research Institute, University of Adelaide, South Australia, 5005, Adelaide (Australia); Shareef, Ali; Kookana, Rai S. [Water for a Healthy Country Research Flagship, Commonwealth Scientific and Industrial Research Organisation (CSIRO), PMB 2, Glen Osmond, South Australia, 5064, Adelaide (Australia)

    2013-03-01

    This study compared the degradation of indigenous bisphenol A (BPA) and triclosan (TCS) in a biosolids-amended soil, to the degradation of spiked labelled surrogates of the same compounds (BPA-d{sub 16} and TCS-{sup 13}C{sub 12}). The aim was to determine if spiking experiments accurately predict the degradation of compounds in biosolids-amended soils using two different types of biosolids, a centrifuge dried biosolids (CDB) and a lagoon dried biosolids (LDB). The rate of degradation of the compounds was examined and the results indicated that there were considerable differences between the indigenous and spiked compounds. These differences were more marked for BPA, for which the indigenous compound was detectable throughout the study, whereas the spiked compound decreased to below the detection limit prior to the study completion. The rate of degradation for the indigenous BPA was approximately 5-times slower than that of the spiked BPA-d{sub 16}. The indigenous and spiked TCS were both detectable throughout the study, however, the shape of the degradation curves varied considerably, particularly in the CDB treatment. These findings show that spiking experiments may not be suitable to predict the degradation and persistence of organic compounds following land application of biosolids. - Highlights: ► Degradation of indigenous and spiked compounds from biosolids were compared. ► Differences were observed for both the rate and pattern of degradation. ► Spiked bisphenol A entirely degraded however the indigenous compound remained. ► TCS was detectable during the experiment however the degradation patterns varied. ► Spiking experiments may not be suitable to predict degradation of organic compounds.

  10. Degassing dynamics at Mount Etna inferred from radioactive disequilibria (210Pb-210Bi-210Po) in volcanic gases

    Terray, Luca; Gauthier, Pierre-Jean; Salerno, Giuseppe; La Spina, Alessandro; Giammanco, Salvatore; Sellitto, Pasquale; Briole, Pierre

    2016-04-01

    Volcanic gases are significantly enriched in the last short-half-life radionuclides of the 238U series, namely the so-called Radon daughters 210Pb, 210Bi and 210Po. Because of their contrasted volatilities, these isotopes are strongly fractionated upon degassing, which gives rise to significant radioactive disequilibria between them in the gas phase. These disequilibria carry precious information on shallow degassing processes beneath active volcanoes: they remarkably constrain the magma residence time in the degassing reservoir and the duration of gas extraction from magma to surface. On Mount Etna (Sicily), where the study of these disequilibria was initiated thirty years ago (Lambert et al., EPSL, 1985-86), no measurement of 210Pb, 210Bi and 210Po in the gases has been performed for the last twenty years. Here we present new 210Pb-210Bi-210Po radioactive disequilibria measurements in volcanic plume gases of Mount Etna. Samples were collected in the bulk diluted plume at kilometric distance from the summit area during the May 2015 eruption, then in more concentrated plumes arising from each summit crater of Etna during quiescent degassing in July 2015. We found values of (210Bi/210Pb) = 7.0 ± 0.3 and (210Po/210Pb) = 80 ± 6 during both periods. These results suggest that 210Pb, 210Bi and 210Po are not significantly fractionated during the transport of the plume from the crater rim to close-downslope sites (<1 km). None of the previous degassing models (Lambert et al., EPSL, 1985-86 ; Gauthier et al., JVGR, 2000) satisfactorily explain measured activity ratios. We propose here a new degassing model based on the previous conceptualization designed for basaltic open-conduit volcanoes, like Stromboli. This model considers extreme Radon enrichments in volcanic gases as a source of 210Pb atoms produced by radioactive decay of 222Rn within gas bubbles travelling to surface. We constrain a magma residence time of 470 ± 170 days and an extraction time of the gases of 4

  11. 226Ra, 210Pb and 210Po levels in marine biota and surface coastal sediments from the Red sea, Sudan

    This paper presents data on 226Ra, 210Pb and 210Po activity concentration levels in multicellular marine algae, molluscs, coral as well as in surface marine sediments collected from the shallower waters of the fringing reefs area extending towards north and south (flamingo bay) of Port Sudan harbour. The analyses were performed adopting a simple time efficient method combining alpha-spectrometry, liquid scintillation and Cerenkov counting technique. generally speaking, surface sediments from this coastal region are poor in their radioactivity content in contrast to similar data reported form different coastal areas around the globe. There is surface enrichment of 210Pb and 210Po with respect to their progenitor 226Ra as it is evident form the activity ratios of 210Pb/226Ra (3.03±1.79) and 210Pb/226Ra (2.23±1.56). Among marine plants and animals investigated, the green algae species, Halimeda, and coral species, Favites, show substantial concentration of radium at 8.2 Bq/kg and 21.9 Bq/kg dry weight, respectively. Similarly, the highest concentration of 210Po was met in the favites at 38.7 Bq/kg followed by brown algae, cytoseria sp., at 32.6 Bq/kg. There is no variation seen among algal species for 210Pb uptake, however, converse to radium and polonium, favites (coral) was found to contain the minimum concentration of lead (3.88). In most species there is preferential accumulation of polonium over its parent radium as indicated by 210Po:226Ra activity ratio with cytoseria (brown algae) showing the highest value at 8.81. On the other hand, 210Po:220Pb activity concentration ratio revealed that coral species favites (9.97) and the brown algae sargassum (1.85) have a greater tendency to accumulate 210Po over220Pb, while in the rest of the species; this ratio is less than unity. (Author)

  12. 210Po and 210Pb levels in mussels and fish from Slovenian market and the related dose assessment

    Polonium-210 (t1/2 = 138 d) is a decay product of uranium-radium decay chain and consequently widely spread in the environment. It enters organisms through direct uptake, ingestion or inhalation. It is a pure alpha emitter and its radiotoxicity is connected with the fact that emits alpha particles with relatively high energy of about 5.3 MeV. It is concentrated in the soft tissues such as mussel, liver and others, where significantly contributes to the internal dose. Beta emitter lead-210 (t1/2 = 22.17 years) is the second highest radiotoxic radionuclide from uranium-238 decay chain and decays, through bismuth-210 (t1/2 = 5.01 d) into 210Po. Therefore it is necessary to determine the 21Po in foods, especially in seafood, because of its accumulation capacity. 210Po and 210Pb were determined in mussels (Mytilus galloprovincialis) and fish (salmon, trout) from Slovenia market. Mussels were bought on the local market as well as from domestic producers. Fish of Slovenian origin were bought on the local market. Samples were freeze dried, homogenized and assayed for 210Po and 210Pb. First, radiochemical separation was performed, followed by alpha particle spectrometric measurement of 210Po and beta counting of 210Pb on a low background gas-flow proportional counter. The results obtained show that the activity concentrations of 210Po in mussels varied from 0.9 to 191 Bq/kg of fresh mass and for fish from 0.3 to 2.12 Bq/kg of fresh mass, while for 210Pb they varied from 1.5 to 6.9 Bq/k of fresh mass for mussels and in fish samples the activity concentrations were less than 1.9 Bq/kg of fresh mass. Combined annual ingestion doses due to 210Po and 210Pb for mussels and fish from the Slovenian market is assessed. (author)

  13. 234Th, 210Pb, 210Po and stable Pb in the central equatorial Pacific: Tracers for particle cycling

    Murray, J.W.; Paul, B.; Dunne, J.P.; Chapin, T.

    2005-01-01

    Samples were collected during the 1992 US JGOFS EqPac Survey I and II cruises from 12??N to 12??S at 140??W in the central equatorial Pacific for water column profiles of dissolved, particulate and total 234Th, 210Pb and 210Po and total acid soluble stable Pb and sediment trap fluxes of 234Th, 210Pb and 210Po. Survey I occurred in February/March with moderate El Nino conditions while Survey II was conducted in September/October when there was a well developed cold-tongue. 234Th, 210Pb and 210Po are all particle reactive yet they partition differently between dissolved and particulate phases. Fractionation factors (the ratios of the distribution coefficients) show that the selectivity for suspended and sediment trap particles follows Th>Po>Pb. Scavenging residence times (??) for 234Th, 210Pb and 210Po ranged from 25 to 100 d, 3 to 8 years and 100 to 500 d, respectively. These particle reactive tracers have very different distributions in the water column, which reflect differences in their sources and sinks. The deficiency of 234Th relative to 238U was fairly uniformly distributed meridionally, though deficiencies were higher during Survey II when there was higher new production. Excess 210Pb relative to 226Ra was very asymmetrical with much higher excess values north of the equator. The distributions were similar for Surveys I and II. The deficiency of 210Po relative to 210Pb had a symmetrical distribution about the equator for both Survey I and II but the deficiencies were larger during Survey I when upwelling was smaller. Stable Pb was generally higher at the surface than at 250 m and there was no meridional trend from 12??N to 12??S. A mass balance for 210Pb was used to determine the atmospheric input of 210Pb. The average values for Surveys I and II were 0.12 and 0.32 dpm cm-2 year-1, respectively. There was no general increase in atmospheric input of 210Pb north of the equator but there was a strong maximum at 2-3??N during Survey I coincident with the

  14. Radionuclides (210Pb, 226Ra, 210Po e 137Cs) in the Cananeia-Iguape coastal system: environmental studies

    This work was developed in the Cananeia-lguape Coastal System, coast south of the State of Sao Paulo, with the aim of monitoring the levels of some natural radionuclides (210Pb, 210Po, 226Ra ) and artificial (137Cs) and to study the sedimentary dynamics of the area. For this, some studies and determinations were carried out, such as: sedimentation rates, concentration factors, bio-indicators and ingestion for the human population of some of these radionuclides. For the obtaining of the levels of these radionuclides, radiochemical and instrumental methodologies were developed and applied in reference samples of the International Agency of Atomic Energy (IAEA). After this, the methodologies were applied in samples of sediments, aquatic organisms and water of the channels collected in several points. In the sediments, the levels of (210Pb, 226Ra and 137Cs varied from 6.1 to 167.5 Bq.kg-1 from 4.1 to 28.5 Bq.kg-1 and from MDC (0.28) to 6.1 Bq.kg-1 respectively. More significant correlations were observed among the percentage of mud (silt-clay) in the sediments and the levels of these radionuclides. These data were used for sedimentation rate studies in the points of sampling in the System. The sedimentation rates obtained with the values of unsupported (210Pb and 137Cs for the Ponta do Arrozal (T1), Ponta do Frade (T2), Valo Grande (T3) and Carapara-BOCA River (T4) were of 5.02 and 5.00 mm.a-1, 2.30 and 3.82 mm.a-1, 14.59 and 15.74 mm.a-1, 3.41 and 5.00 mm.a-1 respectively. The sedimentation rates obtained with unsupported 210Pb and the 137Cs in the cores(T1, T2, T3 and T4) showed a good agreement. The sedimentation rates obtained along the System reflect the dynamics intern of the channels, that presents general tendency the one accentuated deposition process, with pronounced contribution of sediments of continental origin, for the drainages Mandira and Ribeira of Iguape Rivers, by the high biological production of the System as well as the pronounced erosion of the

  15. Temporal and spatial distribution patterns of 210Po/210Pb and their implication in biogeochemical cycle along coastal region of China

    The natural radionuclide 210Po and 210Pb were analyzed in samples of atmospheric deposition (dry+wet), river water, tidal flat sediments and seawater along the coastal region of China. The results showed that the atmospheric deposition fluxes of 210Po and 210Pb with a similar trend in yearly time scale, changing seasonally with a higher value in spring and winter. As the river input (XLJ, fresh water end- number of the Chanjiang River), approximately 86% and 78% of the total 210Po and 210Pb in the water column were in particulate phrase, demonstrating that 210Po and 210Pb was easily absorbed and scavenged by the riverine particles. Except in Feb., Apr. and Oct., the ratio 210Po/210Pb of water column was less than 1.0 showing a deficiency 210Po relative to 210Pb. In surface sediments of east Chongming tidal flat of the Changjiang Estuary, the activities of 210Po and 210Pb were decreasing with the height of tidal flat (from land to seaward), due to the variations of the sediments grain size, the vegetational areas and the hydrodynamics force. Although a bit different from 2009 to 2010, the ratios of 210Po/210Pb were over 1.0 in both of two years, suggesting that 210Po was absorbed onto organic matter in the frequent bioturbation processes. In the coastal water, all the results showed a 210Po-deficiency relative to 210Pb in Yellow Sea since the atmospheric deposition source and bio-scavenge in water column. (author)

  16. Separation of 210Pb, 210Bi and 210Po by ion exchange and their Iiquid scintillation standardization; Separacion del 210Pb, 210Bi y 2I0Po mediante columna de cambio ionico y su calibracion por centelleo liquido

    Rodriguez, L.; Jimenez, A.; Grau, A.

    1996-07-01

    We applied the CIEMAT/NIST method and alpha/beta discrimination to ''210Pb samples in equilibrium with its daughters, by preparing homogeneous and gel samples. The stability of samples was tested in different available cocktails, HiSafe''TM II, HiSafe''TM III, Ultima-Gold''TM, Ultima-Gold''TM XR, Ultima-Gold''TM AB, Insta-Gel''R and e Insta-Gel''R lI. Also we analyzed the disequilibrium of the radioactive chain 210Pb+210Bi+210Po, achieving an excellent agreement between the results of the spectrum unfolding method and the experimental values. (Author) 13 refs.

  17. Chemical characterization and 210Pb dating in wetland sediments from the Nhecolandia Pantanal Pond, Brazil

    Pantanal, located in the central region of South America, is recognized as one of the world's largest freshwater wetlands. In order to verify possible changes in this environment, a study was undertaken in Nhecolandia Pantanal, Mato Grosso do Sul State, Brazil. Two sediment cores from the Salina do Meio pond (SM1 and SM2) and one core from a small flood land named Ba (B5) were collected in 2001. The elements As, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb, Zn and Zr were determined by instrumental neutron activation analysis (INAA). Cluster and factorial analysis were applied to the chemical data. The sedimentation rate in the SM2 core was determined by 210Pb method and the mean value found was 0.61 cm x y-1. The results obtained in the present study showed that recent geochemical processes such as desorption, precipitation and dissolution can contribute for the high water alkalinity and salinity in the saline ponds. (author)

  18. Monitoring of sedimentation using bathymetric changes and 210Pb profiling in Laguna de Bay, Philippines

    Laguna de Bay is the largest inland body of water in the Philippines. It is a multi-use resource but at present, the dominant use is for fishery. At present there is a very high demand for domestic water in the Metropolitan Manila Area and the lake is considered as the most viable source. Among the concerns raised are the eutrophic condition of the lake, the alarming siltation due to the denudation of the forest areas within the watershed, deterioration of the water quality due to rapid development in built-up areas and the booming industrialization in the lake's West Bay area. The dredging of the lake has long been requested by the different stake holders to improve its water quality and to achieve the volume necessary to meet the lake's various uses. In line with the thrust of the Laguna Lake Development Authority to formulate policies on the development of the lake region and the sustainable use of the lake's resources based on concrete and reliable data, a collaborative work with the National Institute of Geological Sciences at the University of the Philippines, Diliman Campus, commenced in 1997. Among the objectives is to generate an updated bathymetric map of the lake and establish the changes in the configuration of the lake during the past few tens of years and to estimate the rates of sedimentation using time series analysis of bathymetric maps and radiometric dating using 210Pb

  19. Application of the 210Pb-dating technique to evaluate environmental changes resulting from recent human activities

    The 210Pb-dating technique has shown particular promise for the study of recent environmental change by enabling the establishment of chronologies for contemporary environmental processes. In this paper two case studies are discussed. Case Study (1) looks at trace element and heavy metal levels in the estuaries of the Georges River and the Hacking River which are partly located in suburban Sydney and Case Study (2) looks at blooms of the toxic dinoflagellate Gymnodinium catenatum which were first observed in Tasmanian waters, principally the Huon and Derwent Rivers in 1980. In both cases the 210Pb dating technique has been used to establish the sequence of sediment deposition in order to associate an age to the sediment layer which contains the entity under investigation

  20. Determination of the sedimentation rates in the Sepetiba bay northeastern area by using dating with the excesses 210 Pb radioisotope

    210 Pb dating, using two modes of data analysis, CIC and CRS, was used to determine sedimentation in the North East part of Sepetiba Bay. 210 Pb was leached from samples using dilute HBr and subsequently separated onto anionic exchange columns, followed by re-extraction and precipitation as Pb CrO4. The original method was modified by the introduction of a pre-digestion step whose purpose was to liberate the lead bound as sulphide. The sedimentation rates found o.68 - 0.98 cm.y-1 were moderate, compared to other authors estimates. Dating using the CRS model showed a maximum rate of sedimentation in the period between 1954 and 1977, when the riverine input was probably at its greatest. The CRS model appears to be more applicable to the data, since it works over longer periods and allows for variations in sedimentation rate. (author)

  1. Application of the {sup 210}Pb-dating technique to evaluate environmental changes resulting from recent human activities

    Jenkinson, A.V.; Chisari, R.; Farrar, Y.J.; Heijnis, H.; McOrist, G.D. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia); Hallegraeff, G. [University of Tasmania, Tasmania, (Australia). Department of Plant Science; Hughes, M.; Napoli, M. [University of Sydney, Sydney, NSW (Australia). Department of Geology and Geophysics; James, J.M. [University of Sydney, NSW, (Australia). School of Chemistry; McMinn, A.; Thomson, P. [University of Tasmania, Tasmania, (Australia). Institute of Antartic and Southern Ocean Studies; Smith, J.D.; Tinker, R.A. [University of Melbourne, Parkville, VIC (Australia). School of Chemistry, Marine Chemistry Laboratory

    1997-10-01

    The {sup 210}Pb-dating technique has shown particular promise for the study of recent environmental change by enabling the establishment of chronologies for contemporary environmental processes. In this paper two case studies are discussed. Case Study (1) looks at trace element and heavy metal levels in the estuaries of the Georges River and the Hacking River which are partly located in suburban Sydney and Case Study (2) looks at blooms of the toxic dinoflagellate Gymnodinium catenatum which were first observed in Tasmanian waters, principally the Huon and Derwent Rivers in 1980. In both cases the {sup 210}Pb dating technique has been used to establish the sequence of sediment deposition in order to associate an age to the sediment layer which contains the entity under investigation 7 refs., 5 figs.

  2. Bioturbation in near-surface sediments from the COMRA Polymetallic Nodule Area:evidence from excess 210Pb measurements

    YANG Qunhui; ZHOU Huaiyang

    2004-01-01

    In order to evaluate bioturbation in sediments from the COMRA Polymetallic Nodule Area in the northeast tropical Pacific, excess 210Pb profiles in sediments cores collected with multiple corers during R/V DAYANGYIHAO Environmental Program Cruise in 1998 were measured by direct gamma assay using Ortec HPGe GWL series well-type coaxial low background intrinsic germanium detectors. A steady-state diffusion model of excess 210Pb profiles suggests that bioturbation mixing depths and biodiffusion coefficients are 16 cm and 2.75 cm2/a in East Zone, and 6 cm and 0.26 cm2/a in West Zone, respectively. Furthermore, the observations of macrofauna and measurements of total organic carbon (TOC) content in sediments suggest that bioturbation is directly controlled by species and abundance of benthic fauna, such as polychaete, and the bioturbation mixing depth and intensity are positively correlated with the organic matter content.

  3. Radiochemical analysis of 210Pb e 226Ra in samples of sludges and scales in petroleum industry

    The exploration and production of oil can generate different types of waste, such as scales, which are formed in the internal surface of pipes and equipment, sludges that is deposited in water/oil separators, storage tanks and valves and water that is removed along with the oil, which bring to the surface some of the radionuclides present in the rock matrix. From a radiological point of view, the most important radionuclides, which appear in sludges and scales are 228Ra, 226Ra, 210Pb and 228Th, since the exposure to these radionuclides can represent a significant dose on workers. The analysis already performed using gamma spectrometry in samples of sludge and scales indicated the presence of high concentrations of radio isotopes, showing the need to enlarge the radiometric survey including other elements of the 238U series. This work focuses on radiochemical determination of 210Pb and 226Ra concentrations in samples of sludge and scales

  4. Apparent discrepancy in contamination history of a sub-tropical estuary evaluated through 210Pb profile and chronostatigraphical markers

    Heavy metal concentrations (Zn, Cd, Cu and Pb), lead stable isotopes (204Pb, 206Pb, 207Pb, and 208Pb), and sediment chronology (210Pb method) were determined in a core from Sepetiba Bay (southeastern coast of Brazil, 30 km west of Rio de Janeiro City). During last decades, this region has been modified by increase of industrial activities, population flows, and by human interventions in the watershed area of the bay. In particular, Zn and Cd emissions are well established to the bay, and inputs started during 1960 and 1970, respectively. The core was sampled in the more contaminated northern part of the bay, in the tidal flat in front of the Coroa Grande mangrove. This area is located near to the Sao Francisco Channel, which accounts for 86 % of the freshwater supply to the bay, and receive waters from the Paraiba do Sul River (another watershed) since 1950s. The proxies at the sediment core showed three successive events: at the depth of 50-52 cm, a marked change in the stable lead isotopic ratios; at 38-42 cm depth, the beginning of the Zn concentration upwards increase; and above 30 cm, relatively high Cd concentrations. Such records can easily be explained by the local metallurgic development history. However, sediment accumulation rates evaluated using these reference levels are higher than those calculated from the 210Pb profile by using either the Constant Initial Concentration (CIC) or the Constant Rate of Supply (CRS) models. One possible interpretation can be provided by local hydrodynamics, which has been strongly influenced by deposition of particles transported by runoff in the core site. The main source of these particles may be the mangrove flat that experimented enrichment of unsupported 210Pb by trapping it from the rain. A model, taking into account the exponential increase of the initial 210Pb activity observed in the core allows the calculated rates to fit well with those evaluated from the 'historic' events. (author)

  5. Factors affecting 210Po and 210Pb activity concentrations in mussels and implications for environmental bio-monitoring programmes

    The activity of 210Po and 210Pb was determined in mussels of the same size (3.5-4.0 cm shell length) sampled monthly over a 17-month period at the Atlantic coast of Portugal. Average radionuclide concentration values in mussels were 759 ± 277 Bq kg-1 for 210Po (range 460-1470 Bq kg-1 dry weight), and 45 ± 19 Bq kg-1 for 210Pb (range 23-96 Bq kg-1 dry weight). Environmental parameters and mussel biometric parameters were monitored during the same period. Although there was no seasonal variation of radionuclide concentrations in sea water during the study period, the concentration of radionuclide activity in mussels varied seasonally displaying peaks of high concentrations in winter and low concentrations in summer. Analysis of radionuclide data in relation to the physiological Condition Index of mussels revealed that 210Po and 210Pb activities in the mussel (average activity per individual) remained nearly constant during the investigation period, while mussel body weight fluctuated due to fat storage/expenditure in the soft tissues. Similar variation of radionuclide concentrations was observed in mussels transplanted from the sea coast into the Tejo Estuary. However, under estuarine environmental conditions and with higher food availability throughout the year, transplanted mussel Condition Index was higher than in coastal mussels and average radionuclide concentrations were 210 ± 75 Bq kg-1 (dry weight) for 210Po and 10 ± 4 Bq kg-1 (dry weight) for 210Pb, therefore lower than in coastal mussels with similar shell length. It is concluded that the apparent seasonal fluctuation and inter-site difference of radionuclide concentrations were mostly caused by mussel body weight fluctuation and not by radionuclide body burden fluctuation. This interpretation can be extended to the apparent seasonal fluctuation in concentrations of lipophilic and lipophobic contaminants in mussels, and provides an explanation for occasional high concentrations of 210Po and man

  6. Evaluation of the chromium contamination at Ribeirão dos Bagres, Franca (SP), Brazil, by the 210Pb method

    This paper presents a chronological study focusing the use of 210Pb in four sediment cores collected at Ribeirão dos Bagres in the region of Franca, São Paulo State, Brazil. When evaluating the sedimentation rate by using the 210Pb method, it was possible to monitor historical changes occurring in the concentrations of chromium present in the sediments. In order to do so, several specific parameters were determined in sediments, as chromium concentration, major oxides, organic matter, grain size, and chemical and physical–chemical parameters of waters. The sediments possessed a Cr concentration range of 0.83–26.25 mg/kg that is below the world's average of shales. The sedimentation rates obtained from the 210Pb analysis were between 0.07 and 0.77 g cm−2 year−1, while the linear sedimentation rate was from 0.6 to 3.2 cm/year. The adoption of the CIC (Constant Initial Concentration) 210Pb model allowed characterize older sediments, aged 177 years, and younger sediments, aged 4 years. The organic matter in the sediments was more abundant in the first few centimeters of practically all profiles, and the analysis of oxides showed that silica is the major constituent of the sediments, in which there is predominance of sand and silt. In addition, the analysis of the physical and chemical parameters of waters indicated that they are suitable for navigation and natural harmony landscape. - Highlights: • Application of natural radionuclides in an important industrial center devoted to the production of leather for manufacturing shoes. • Study of a well-known site of environmental Cr contamination. • Use of the Pb-210 chronological CIC model to provide an approach of the historical Cr contamination in the region

  7. Impact of 210PB from Osamu Utsumi mine on sediment of rivers in Caldas Region, Minas Gerais

    The Osamu Utsumi Mine of the Industrias Nucleares do Brasil (INB) is located in Caldas region, Minas Gerais, Brazil. It is a uranium mining and is in process of shutdown, decommissioning stage. CDTN/CNEN (Nuclear Technology Development Center, sponsored by Brazilian Commission for Nuclear Energy) is participating in this decommission step. One contribution will be the characterization of the environmental liability, determining the impact on the environment caused by mining activities. Several radionuclides are being analysed in diversified matrixes, however, this paper is about determination of 210Pb in sediment of rivers. One reason to analyse 210Pb is due to its long half-life (22.3 years) that may point out the carrier of 222Rn, 226Ra, 228Ra, even U, in the region. Besides, it may be used to date sediment. The methodology applied to determine the 210Pb activity in sediment was gamma spectrometry that was established at CDTN during the development of this study. The results confirmed the impact of the uranium mining on the environment. (author)

  8. Seasonal change of sedimentary environment in the Mekong Delta investigated by 7Be, 210Pb and radioactive Cs isotopes

    Radioactivities of 7Be as well as 210Pb and radioactive Cs isotopes were measured in the core samples taken at the Mekong delta, Vietnam, in wet and dry seasons to understand the seasonal change of sedimentary environment. Activity of 7Be was detected in the surface samples (up to ∼30 cm in depth) of the core sediment taken 195 m off from the shore in the wet season (October 2011), while it was under detection limit even at the very surface of the core sediment taken in the next dry season (February 2012). Activity of excess 210Pb was almost constant, suggesting the fast sedimentation. Furthermore activities of 134Cs and 137Cs that were released from the Fukushima Dai-ichi Nuclear Power Plant, Japan, in March 2011 by the extraordinary earthquake and tsunami accident were detected only in the upper samples (5-15 cm in depth) taken in the wet season (October 2011). These facts imply that new surface sediment was deposited fast in the wet season and that it was removed in the next dry season (about 3 months later). The 7Be, 210Pb and radioactive Cs isotopes are proved to be good tools for the research on delta sediments. (author)

  9. Dating human skeletal remains using a radiometric method: biogenic versus diagenetic 90Sr and 210Pb in vertebrae.

    Schrag, Bettina; Uldin, Tanya; Mangin, Patrice; Froidevaux, Pascal

    2012-07-10

    In forensic science, there is a strong interest in determining the post-mortem interval (PMI) of human skeletal remains up to 50 years after death. Currently, there are no reliable methods to resolve PMI, the determination of which relies almost exclusively on the experience of the investigating expert. Here we measured (90)Sr and (210)Pb ((210)Po) incorporated into bones through a biogenic process as indicators of the time elapsed since death. We hypothesised that the activity of radionuclides incorporated into trabecular bone will more accurately match the activity in the environment and the food chain at the time of death than the activity in cortical bone because of a higher remodelling rate. We found that determining (90)Sr can yield reliable PMI estimates as long as a calibration curve exists for (90)Sr covering the studied area and the last 50 years. We also found that adding the activity of (210)Po, a proxy for naturally occurring (210)Pb incorporated through ingestion, to the (90)Sr dating increases the reliability of the PMI value. Our results also show that trabecular bone is subject to both (90)Sr and (210)Po diagenesis. Accordingly, we used a solubility profile method to determine the biogenic radionuclide only, and we are proposing a new method of bone decontamination to be used prior to (90)Sr and (210)Pb dating. PMID:22497702

  10. Development, implementation and utilization of 210Pb in vivo measurement techniques as indicator of human being exposure to 222Rn - evaluation of associated parameters

    Radon and its decay products are present in the atmosphere and are the most important contributors for the internal exposure of humans to natural radiation. The execution of in vivo measurements of 210Pb in the population and in individuals occupationally exposed in underground mines has been studied and recommended as one of the procedures for the estimation of the exposure to 222Rn. The metabolism of 210Pb and its distribution within the human body, mainly deposited in the bone tissue, suggests the regions of skull and knee as the most suitable for the in vivo monitoring of such radionuclide. A radiological survey in non uranium mines in Brazil indicated that an underground coal mine in the State of Parana, in the south of Brazil, had high radon concentration. The aim of this work were: (1) To investigate whether underground coal miners may also have elevated 210Pb in the skeleton as a result of occupational exposure to radon in the coal mine; (2) To estimate the committed equivalent dose and the committed effective dose in different incorporation scenarios using a computer code. The calibration and the in vivo measurements of underground coal miners were performed in the IRD-CNEN Whole Body Counter shielded room using an array of four high resolution germanium detectors. The detection system was positioned at the head and knee geometries. The minimum detectable quantity of 210Pb in the skeleton using this methodology was (50 Bq) and the positive results were verified using a mathematical method that applies a moving median smoothing function to the total spectrum for each measurement. In vivo measurements of 210Pb in 6 out of the 32 underground coal miners ranged between 83 Bq and 164 Bq suggesting that these workers received significant occupational cumulative exposure to 222Rn. The simulation of some exposure patterns of 222Rn progeny and 210Pb incorporation showed that the most important contribution for 210Pb skeleton deposition was the intake of 214Pb and

  11. A temporal increase in the atmospheric 210Pb concentration possibly due to the 1991 eruption of Pinatubo volcano. An observation at Seoul, the Republic of Korea

    A temporal increase in the atmospheric concentration of 210Pb was observed in December, 1991, and January, 1992, at Seoul, the Republic of Korea. This increase was estimated to be due to the fallout of the stratospheric 210Pb originating from the 1991 eruption of Pinatubo volcano, Philippines, along with the aerosol particles injected into the stratosphere by the eruption. The present observation was similar to the previous observations made at Tsukuba Science City, Japan. (author)

  12. 210Pb and 210Po in sediments and suspended matter in the Tagus estuary, Portugal: Local enhancement of natural levels by wastes from phosphate ore processing industry

    Results of analyses of uranium series radionuclides in phosphate ore and in wastes released by the phosphate fertilizer industry confirm their potential for the enhancement of environmental radioactivity levels. Therefore, concentrations of 210Pb and 210Po were measured in bottom sediments and suspended matter in the Tagus estuary, Portugal, to assess the enhancement of radioactivity due to wastes from the phosphate industry. The concentration of 210Pb in surface sediments in the estuary increased inversely with sediment grain-size; conversely, increased percentage of sand has a dilution effect on the concentration of 210Pb measured in bulk sediment samples. By normalizing the data to the 210Pb in sediments was found to be 68 ± 19 Bq kg-1 (dry wt.) in background sediments. Higher 210Pb levels, up to 1580 Bq kg-1 (dry wt.), were measured in some bulk sediment samples. It was verified that this radionuclide has been introduced by the discharge of wastes from a phosphate fertilizer plant but enhanced concentrations are localized near the point of discharge. In other zones of the estuary, the concentrations of 210Pb in sediments and suspended matter were generally below those measured in the zone of phosphatic releases at the Barreiro Peninsula. Concentrations higher than the predicted average concentration of unsupported 210Pb from natural sources (atmospheric deposition, river input) were also measured in the upper estuary, both in bottom sediments and in suspended matter. It is suggested that these relatively elevated concentrations are due to the highly efficient scavenging of soluble naturally-occurring unsupported 210Pb onto suspended matter and to co-precipitation with iron-manganese hydroxides in the fresh water-salt water mixing zone

  13. The effect of CaNa2EDTA on excretion of 210PB, 210Po and stable lead in cases of chronic lead intoxication

    The study describes the effect of CaNa2EDTA on the excretion of the naturally occurring radionuclides 210Pb, 210Po and stable lead in workers' urine. The CaNa2EDTA was administered intravenously to workers in the morning for five days. The results show that CaNa2EDTA mobilises biologically active 210Pb, 210Po and stable lead, appreciably increasing their concentration in urine. (author)

  14. Estimation of the Arctic aerosols from local and long-range transport using relationships between 210Pb and 212Pb atmospheric activity concentrations

    In this study, the aerosol activity concentrations of 210Pb at 28 Canadian radiological monitoring stations from 2009 to 2013 were analyzed. The results show that the ratio of 210Pb winter average concentration to summer average concentration increases with increasing latitude. This could be used to evaluate the transport of pollutants to the Arctic region such as the Arctic haze from Eurasia through long-range atmospheric transport during winter. Based on 12 years of monitoring results from the Yellowknife station that includes both 210Pb and 212Pb concentrations, the study confirms that the seasonal distribution of 210Pb to 212Pb activity concentration ratios has a significant peak in winter and a relatively low value in summer, which can be used as an indicator of the air mass flow to the Arctic. The period dominated by long-range aerosol transport and Arctic haze was estimated by fitting a Gaussian distribution function to the peak values of this ratio in winter. A peak width parameter of full width at half maximum (FWHM) allows a year by year estimate of the period of influence by long-range transport of aerosols, and this varied between 67 and 88 days in this study. The fitted Gaussian peak also shows that the season of the continental influenced air mass in Yellowknife usually starts in mid-to-late November and ends in mid-to-late April. Thus, the 210Pb to 212Pb ratio distributions may enable the determination of periods dominated by long-range aerosol transport and the scale of the Arctic haze at different latitudes. - Highlights: • Twelve years 210Pb/212Pb monitoring results from low to high altitude are presented. • The 210Pbwinter/210Pbsummer ratio increases clearly with latitude of monitoring site. • The pollutant transport to the Arctic is estimated by distribution 210Pb/212Pb ratio. • The time scale of long-range transport aerosol bearing 210Pb to Arctic is reported

  15. The behavior of particle-reactive tracers in a high turbidity environment: 234Th and 210Pb on the Amazon continental shelf

    Excess 234Th and 210Pb seabed inventories were measured in cores collected from the Amazon continental shelf to examine particle scavenging and seabed dynamics. Typical excess 210Pb inventories range from 100 to 300 dpm cm-2, and the total excess 210Pb inventory for the Amazon shelf was determined to be 2.7 x 1017 dpm. The 210Pb measurements indicate that particle-reactive species are scavenged not only form the Amazon River but also from the lateral advection of offshore water. In order to sustain the 210Pb inventories, the volume of water supplied by the lateral advection from offshore must be approximately five to ten times the water discharge of the Amazon River. This lateral advection supplies about 67% of the total excess 210Pb to the Amazon continental shelf with relatively small contributions from riverine input (31%), atmospheric fallout (2.3%), and in-situ production (0.1%). The 234Th inventories were measured on four cruises, which occurred during periods of differing river discharge, wind stress, and flow rates of the North Brazil Current. The 234Th excess seabed inventories show large spatial and seasonal variability, with a range from 0 to 22 dpm cm-2. This approach indicates that for most of the shelf, the inventories of the shorter-term tracer (234Th) are less than predicted by the inventories of the longer-term tracer (210Pb). There are two explanations for this trend. The first is that a larger portion of the 234Th inventory occurs in the fluid muds or the water column relative to 210Pb. The second is that the supply of offshore water, scavenging efficiency, and/or deposition have been lower over the two year study period relative to the last one hundred years. 38 refs., 7 figs

  16. Application of Constant Rate of Supply model (CRS) in dating of Guanabara Bay sediments using 210Pb measures

    A geochronological study of the Guanabara Bay (Rio de Janeiro, Brazil) based on 210Pb dating technique to determine sedimentation rates and using the Constant Rate of Supply model (CRS) is presented in this work. Sediment samples were collected from river-head of Estrela, Sao Joao de Meriti, Guapimirim, Guaxindiba e Imbuacu. A low energy gamma spectrometry (210Pb, samples taken from the Estrela and Sao Joao de Meriti rivers. Radiochemical method was applied to determine the amount of 210Pb in samples collected near Guapimirim, Guaxindiba and Imbuacu Rivers. Atomic absorption spectrometry with air-acetylene flame technique was used to determine the amount of copper in all these samples. Experimental data shown the following variation in the concentration levels of copper and 210Pb: (i) copper; from 2.5 μg/g to 37.1 μg/g (Imbuacu River); from 3.6 to 228.1 μg/g (Estrela River); from 11.6 to 73.4 μg/g (Guapimirim River); from 12.0 to 52.9 μg/g (Guaxindiba River) and from 90.8 to to 237.7 μg/g (Sao Joao de Meriti River), (ti) 210Pb; from 2.0 Bq/kg to 27.0 Bq/kg (Imbuacu River); from 25.2 to 136.6 Bq/kg (Estrela River); from 40.0 to 90.0 Bq/kg (Sao Joao de Meriti River); from 7.0 to 70.0 Bq/kg (Guapimirim River); from 10.0 to 48.0 Bq/kg (Guaxindiba River). The sedimentation rates ranged from 0.30 cm/y in the Imbuacu River for a depth below of 35 cm to 1.3 cm/y for 0-30 cm depth in Guaxindiba River. It was concluded that the experimental data found in this work are consistent with those published in the scientific literature and that they can be predicted by the CRS model. (author)

  17. Inventory of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb in marine sediments cores of Southwest Atlantic Ocean

    Costa, Alice M.R.; Oliveira, Joselene de, E-mail: alice.costa@usp.br, E-mail: jolivei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Gerencia de Metrologia das Radiacoes. Lab. de Radiometria Ambiental; Figueira, Rubens C.L.; Mahiques, Michel M.; Sousa, Silvia H.M., E-mail: rfigueira@usp.br, E-mail: mahiques@usp.br, E-mail: smsousa@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto Oceanografico

    2015-07-01

    {sup 210}Pb (22.3 y) is a radioactive isotope successfully applied as tracer of sediment dating of the last 100-150 years. The application of {sup 226}Ra and {sup 228}Ra as paleoceanographic tracers (half-lives of 1,600 y and 5.7 y, respectively) also gives some information of ocean's role in past climate change. In this work, it was analyzed 2 sediment cores collect at Southwest Atlantic Ocean. The sediments samples were freeze-dried and acid digested in microwave. It was carried out a radiochemical separation of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb and performed a gross alpha and gross beta measurement of both precipitates Ba(Ra)SO{sub 4} and PbCrO{sub 4} in a low background gas-flow proportional counter. Activity concentrations of {sup 226}Ra ranged from 45 Bq kg{sup -1} to 70 Bq kg{sup -1} in NAP-62 and from 57 Bq kg{sup -1} to 82 Bq kg{sup -1} in NAP-63 samples. The concentration of {sup 228}Ra varied between 37 Bq kg{sup -1} and 150 Bq kg{sup -1} in NAP-62 and between 23 Bq kg{sup -1} and 111 Bq kg{sup -1} in NAP-63 samples. The concentration of total {sup 210}Pb ranged from 126 Bq kg{sup -1} to 256 Bq kg{sup -1} in NAP-62 and from 63 Bq kg{sup -1} to 945 Bq kg{sup -1} in NAP-63 samples. Results of {sup 210}Pb{sub uns} varied from 68 Bq kg{sup -1} to 192 Bq kg{sup -1} for NAP-62, while varied from <4.9 Bq kg{sup -1} to 870 Bq kg{sup -1} in NAP-63 profile. Increased values of {sup 210}Pb{sub uns} were found on the top of both NAP-62 and NAP- 63 sediment profile. (author)

  18. Apparent discrepancy in contamination history of a sub-tropical estuary evaluated through 210Pb profile and chronostratigraphical markers.

    Marques, Aguinaldo N; Monna, Fabrice; da Silva Filho, Emmanoel V; Fernex, François E; Fernando Lamego Simões Filho, F

    2006-05-01

    Zn and Cd concentrations, stable lead isotopes and 210Pb-derived chronology were determined in a sediment core sampled at Sepetiba Bay (South-eastern Brazil). During the last decades, the bay's watershed has been modified by the increase of industrial activities and human interventions. In particular, Zn and Cd ore treatment plants were built near the coast in 1960 and 1970, respectively, and water has been diverted from the adjacent Paraíba do Sul River watershed since 1950. The core collected at shallow depth near the industrial area exhibits four successive events: (i) at 50 cm depth, a change in the 206Pb/207Pb ratio from about 1.162 to more than 1.18 might be the result of the São Francisco Channel opening and water diversion from Paraíba do Sul river; (ii) at 40 cm depth, Zn concentration starts to increase (up to 0.8 mg g(-1)) (iii) above 30 cm depth, relatively high Cd concentrations (up to 1.6 microg g(-1)) are observed and (iv) at 16 cm depth, change in unsupported 210Pb slope is probably related to a waste dam built to prevent strong metal contamination in the bay. Sediment accumulation rates evaluated by Zn and Cd profiles used as time-markers are higher than those calculated from 210Pb-based chronology models. Using the constant initial concentration (CIC) model both events are supposed to date back to about 1884 and 1902, respectively, while using the constant rate of supply (CRS) model it shifts to about 1925 and 1935. Such discrepancies are probably assigned to the fact that these models do not take into account site-specific local sedimentation dynamics. In the study area, particles deposition seems to be controlled by enrichment with unsupported 210Pb transported by runoff from a mangrove flat bank. Chronology derived from a model that assumes an exponential increase of the initial 210Pb activity fits well with the estimated rates obtained from historical events. PMID:16309713

  19. Incorporation of 210Pb and 210Po to Poultry through the Addition of Dicalcium Phosphate (DCP) to the Diet

    Casacuberta, N.; Masqué, P.; Garcia-Orellana, J.; Gasa, J.; Anguita, M.

    2008-08-01

    Due to the replacement of calcium by uranium in the phosphorite, sedimentary phosphate rock contains high concentrations of 238U (i.e. from 1500 Bqṡkg-1 in Morocco to 4000 Bqṡkg-1 in Tanzania ores). Dicalcium Phosphate (DCP) is produced by the wet acid digestion of the phosphorite, and is used as a source of calcium and phosphorus for livestock feed supplement. If the phosphorite acid digestion is made with hydrochloric acid, DCP may present specific activities of about 103 Bqṡkg-1 of 238U and some of its decay chain daughters. In particular, due to its radiological implications, the presence of 210Pb and 210Po in DCP is of special relevance. The aim of this work was to investigate the potential incorporation of these radionuclides to poultry through its diet. Three different diets were therefore prepared with different contents of both DCP and 210Pb and 210Po. Diet A was used as a blank, and had a 2.5% in weight of monocalcium phosphate (MCP); diet B, with a 5% in weight of DCP; and diet C, with a 2.5% of DCP. Concentrations of 210Pb were 0.93, 101.4 and 51.2 Bqṡkg-1; whereas concentrations of 210Po were 0.92, 74 and 36 Bqṡkg-1 of food for diets A, B and C, respectively. Accumulation of 210Pb and 210Po was analysed at several times during poultry growth in samples of bone, liver, kidney, muscle, excrements as well as entire animals, with a total of 30 broilers fed with the 3 different diets. Results showed clear enhancements in the accumulation of both 210Pb and 210Po in chicken for diets B and C, and in particular in liver and bone. However, total accumulation of radionuclides in chicken, and especially in edible parts, is low compared to its expulsion through excrements. These results are interpreted in terms of the potential dose through consumption of chicken.

  20. Atmospheric deposition fluxes of 7Be, 210Pb and chemical species to the Arabian Sea and Bay of Bengal

    Aerosol samples collected close to the air-sea interface, between February 1997 to February 1999, over the Arabian Sea and Bay of Bengal were analyzed to determine the atmospheric dry-deposition of Fe (dust inputs), anthropogenic constituents (NO3-, SO42-) and environmental nuclides (7Be, 210Pb). In general, aerosol 210Pb concentrations showed a good correlation with 7Be, suggesting the long-range transport of 210Pb from the continents (via upper troposphere) and similarities in the processes governing their deposition through the marine boundary layer (MBL). The relatively low 7Be/210Pb ratios observed over the Bay of Bengal, during February 1999, are dominated by aerosol transport from the continental surface sources. The dry deposition fluxes of 210Pb and 7Be, to these two oceanic regions, average around 245 and 1860 Bq m-2 y-l, respectively. The non-sea-salt (nss) SO42- (range: 1.7 to 9.4 μg m-3) and NO3- (range: 0.6 to 4.1 μg m-3) are uncorrelated in the MBL, presumably because continental pollution sources for SO42- overwhelm the transport of NO3- from crustal dust and biomass burning. The oceanic biogenic emission (DMS) constitutes a very minor source for nss-SO42-. The enhanced concentrations of aerosol NO3- and Fe observed over the Arabian Sea are attributed to dust storm activities from the adjacent desert areas (Saudi Arabia and Thar). Significant scatter in the linear regression analyses indicate that the aerosol composition along the coastal tracks is different from those transported to the open ocean. On average, dry deposition fluxes of N-NO3 and non-marine SO42- are 150 and 1225 mg m-2 y-1, respectively. In contrast, dry deposition of Fe over the Arabian Sea (255 mg m-2 y-1) far exceeds that over the Bay of Bengal (93 mg m-2 y-1). Thus, dust from desert regions appears to be a potential source of micronutrients (Fe) to the surface Arabian Sea. (author)

  1. Radiochemical determination of {sup 210} Pb and {sup 226}Ra in petroleum sludges and scales; Determinacao radioquimica de {sup 210} Pb e {sup 226}Ra em borras e incrustacoes de petroleo

    Araujo, Andressa Arruda de

    2005-07-01

    The oil extraction and production, both onshore and offshore, can generate different types of residues, such as sludge, that is deposited in the water/oil separators, valves and storage tanks and scales, which form i the inner surface of ducts and equipment. Analyses already carried out through gamma spectrometry indicated the existence of high radioisotope concentration. However, radionuclides emitting low-energy gamma-rays, such as {sup 210} Pb, are hardly detected by that technique. Consequently, there is a need to test alternative techniques to determine this and other radionuclides from the {sup 238} U series. This work, therefore, focuses on the radiochemical determination of the concentration of {sup 210}Pb, and {sup 226} Ra in samples of sludge and scale from the oil processing stations of the UN-SEAL, a PETROBRAS unit responsible for the exploration and production of petroleum in Sergipe and Alagoas. The sludge and scale samples went through a preliminary process of extraction of oil, in order to separate the solid phase, where the largest fraction of the radioactivity is concentrated. After oil removal, the samples were digested using alkaline fusion as an option for dissolution. Finally, their activity concentration was determined for the samples of sludge and scales, using and alternative radiochemical method, which is based on ionic exchange. The activity concentration found for {sup 210}Pb varied from 1,14 to 507,3 kBq kg{sup -1}. The values for {sup 226}Ra were higher, varying from 4,36 to 3.445 kBq kg{sup -1}. The results for {sup 226}Ra were then compared with the ones found for the same samples of sludge and scales using gamma spectrometry. The results of the comparison confirm the efficiency of the methodology used int hi work, that is, radiochemical determination by means of ionic exchange. (author)

  2. Modelling the evolution of 210Pb and 210Po size distributions in the atmosphere

    The study of radon (222Rn and 220Rn) decay products in the atmosphere is important for estimating air ionization, assessing the inhalation doses to humans and for understanding atmospheric transport processes. The decay products 218Po, 214Pb (T1/2 < 1 hour), 212Pb (T1/2 ∼ 10.6 hrs) are short lived and 210Po (T1/2 ∼ 13 days), 210Pb (T1/2 ∼ 22 years) are long lived. Within a short time after their formation, the decay product atom combine with air constituents to form molecular clusters which then get attached to existing aerosol particles. The activity size distributions of the short-lived components in the atmosphere show two major modes, namely fine and coarse modes. The long-lived components predominantly occur in the coarse mode. Several studies have been carried out on the decay product activity distributions to estimate their atmospheric residence times. An important aspect that has received little attention is the upward size evolution of the decay products due to the persistent coagulation of the coarse mode particles. The present study aims at the development of first principle model for progeny attachment dynamics to a coagulating aerosol, which will provide insight in understanding the evolution of activity size distribution. A theoretical model is formulated by considering the processes such a constant formation of background aerosols, attachment of progeny atoms to the aerosol, coagulation, physical decay, and deposition. A set of integro-differential equations for attached and unattached fractions are formulated and are solved by a comprehensive numerical approach. Comparative studies of the activity size distributions, the degree of mixing of radioactivity within particles are carried out for short-lived and long lived species. The results are in agreement with the observations which show that the mode of the activity size distribution strongly depends on the effective life time of the progeny species in the atmosphere. The size dependence of

  3. 210Po and 210Pb trophic transfer within the phytoplankton–zooplankton–anchovy/sardine food web: a case study from the Gulf of Lion (NW Mediterranean Sea)

    The transfer of 210Po and 210Pb in the food web of small pelagic fishes (from phytoplankton and zooplankton to anchovy Engraulis encrasicolus and sardine Sardina pilchardus) is investigated in the Gulf of Lion (GoL). We present original data of 210Po and 210Pb activity concentrations, C and N stable isotope ratios, measured (i) from different size classes of phytoplankton and zooplankton during spring and winter in different environments of the GoL, and (ii) in two fish species. Significant spatial patterns based on 210Po, 210Pb activity concentrations and 210Po/210Pb ratios in the different plankton size classes are evidenced by hierarchical clustering, both in spring and winter. This variability, also observed for C and N stable isotopes ratios, is connected to local specific pelagic habitats and hydrodynamics. The sampling strategy suggests that 210Po bioaccumulation in the GoL remains at a constant level from the first (dominated by phytoplankton) to the second trophic level (zooplankton), while 210Pb bioaccumulation shows an increase in winter. Based on stable N isotope ratios and 210Po activity concentrations measured in anchovies and sardines, we evidence 210Po bio-magnification along the trophic food web of these two planktivorous pelagic fishes. - Highlights: • 210Po and 210Pb activity concentrations in plankton vary up to a factor of two in the Gulf of Lion (East vs West). • 210Po and 210Pb variability is connected to local specific pelagic habitats. • Bio-magnification of 210Po is evidenced in anchovy/sardine foodwebs

  4. Time series study of a 17-year record of 7Be and 210Pb fluxes in northern Taiwan using ensemble empirical mode decomposition

    Using the ensemble empirical mode decomposition (EEMD) and a significance test method, we have analyzed time series data on the fluxes of 7Be and 210Pb collected over a span of 17 y in Northern Taiwan. Among nine intrinsic mode functions (IMFs) extracted from the method five (IMF4–8) are non-trivial for 210Pb and have adequate S/N with significant power in localized windows around the periodicities of 0.5 y, 1 y, 2 y, 5 y, and 11 y, respectively. For 7Be, IMF5 and IMF8 with periods around 1 y and 11 y, respectively, have adequate S/N. The semi-annual and annual cycles represented by IMF4 and IMF5, respectively, are dominated by East Asian monsoon. The sum of IMF6 and IMF7 reveals an inter-annual cycle where both 7Be and 210Pb fluxes are well-correlated with the East Asian winter monsoon index (EAWMI). The close tracking of the 210Pb and 7Be in IMF8 cases may reflect an 11 y cycle; implying that it is caused by common climatologic factors, likely related to solar cycle, rather than their distinct production modes. - Highlights: • Using EEMD method to study the time series of 7Be and 210Pb. • The results provide probable factors controlling 7Be and 210Pb including monsoon delivery, deposition and solar modulation. • We also discussed the probable factors controlling abnormal 210Pb fluxes by analyzing dust records

  5. Assessment of radiation dose from 210Pb and 210Po due to chewing tobacco leaves and smoking cigarettes - an Indian scenario

    The study of 210Pb and 210Po content in tobacco and its products is essential because of their elevated concentrations. The cumulative alpha-radiation dose delivered to humans from inhaled 210Po in cigarette smoke becomes significant. 210Pb is another element of interest since it is the precursor to 210Po in the radioactive decay chain of 238U. Further, in India the ingestion dose due to these radionuclides becomes significant because of chewing tobacco leaves. In the present study, the concentrations of these two radionuclides were determined in dried tobacco leaves and some branded cigarettes. 210Pb was determined by counting the beta activity of 210Bi with a low background beta counter after radiochemical separation and precipitation. 210Po was determined by alpha counter after radiochemical separation and deposition of polonium on silver disc. 210Pb and 210Po concentrations in dry tobacco leaves ranged from 6.0 to 30.5 mBq/g (mean 15.8 mBq/g) and 5.6 to 29.3 mBq/g (mean 12.7 mBq/g). The average annual committed effective dose for the tobacco chewers (10 g/day) was estimated to be 95.5 μSv/y (39.9 μSv/y from 210Pb and 55.6 μSv/y from 210Po). 210Pb and 210Po concentrations in branded cigarettes ranged from 11.0 to 18.4 mBq/cigarette (mean 41.2 mBq/cigarette) and 10.5 to 16.6 mBq/cigarette (mean 13.1 mBq/cigarette). The average annual committed effective dose for the smokers (20 cigarettes per day) was estimated to be 149.8 μSv/y (39.8 μSv/y from 210Pb and 110.0 μSv/y from 210Po). (author)

  6. Evaluation of the activity concentration of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb in sediments from Antarctica in the Admiralty Bay region

    Mora, Tamires de A.; Oliveira, Joselene de, E-mail: tamires.mora@usp.br, E-mail: jolivei@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Figueira, Rubens C.L.; Mahiques, Michel M.; Sousa, Silvia H.M., E-mail: rfigueira@usp.br, E-mail: mahiques@usp.br, E-mail: smsousa@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto Oceanografico

    2015-07-01

    In this study, we performed the radiochemical characterization of a sedimentary record (1B profile), collected in the vicinity of Admiralty Bay, King George Island in Antarctic Operation XXXI (January/2013). The activities of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb were determined by the counting of gross alpha and gross beta activities in the precipitates of Ba(Ra)SO{sub 4} and PbCrO{sub 4}. Those measurements were carried out in a low background gas flow proportional detector. The {sup 226}Ra and {sup 228}Ra were measured after 21 days of the final precipitation. The {sup 210}Pb activity was determined after 10 days of the precipitation date by gross beta counting of its {sup 210}Bi decay product. The activity concentration of {sup 226}Ra ranged from 11±1 (mBq g-1) to 54±3 (mBq g{sup -1}), and the {sup 228}Ra ranged from 48±5 (mBq g{sup -1}) to 155±16 (mBq g{sup -1}). The activity concentration of {sup 210}Pb varied from 8±1 (mBq g{sup -1}) to 458±46 (mBq g{sup -1}), while unsupported {sup 210}Pb ranged from 6±1 (mBq g{sup -1}) to 434±65 (mBq g{sup -1}). The {sup 210}Pb concentrations in sediments have often been used to dating events like deposition and accumulation in various marine environments. Taking into account the results of {sup 210}Pb and {sup 226}Ra activities obtained in testimony-1B it was estimated the unsupported {sup 210}Pb activity which was applied to the CIC geochronological dating model (Constant Initial Concentration). Based in these data, the sedimentation rate obtained was 0.63±0.02 cm year{sup -1}. (author)

  7. Radiochemistry determination of activity concentration of 210Pb in sludge and scale samples of UN-SEAL PETROBRAS, Sergipe

    The presence of radionuclides of the 238U and 232Th series in sludge and scales generated inactivities of oil E and P is a well known phenomenon. Scales formed in the inner surface of ducts are constituted basically of CaCO3 and BaSO4 precipitates, being responsible for the gradual reduction in oil production. Sludge, on the other hand, is a mixture of solid debris (sand and rust particles) and oil that accumulate in the bottom of vessels (storage tanks and separators) normally in the form of sulfate and carbonate deposits. The most important radionuclides normally found in sludge and scale are 226Ra, 228Ra, 210Pb and 228Th. The presence of these radionuclides may cause a significant dose to workers, with the consequent increase in the risk of stochastic effects. A program of studies aiming to determine the activity concentration of radionuclides of the two above mentioned series in scales and sludge samples collected in an E and P unit of PETROBRAS in the State of Sergipe (UN-SEAL), is under way in the Department of Nuclear Energy of the Federal University of Pernambuco (DEN/UFPE). The analyses already carried through by gamma spectrometry had indicated the existence of high concentrations of radium, showing the necessity of extending the survey for other elements of the 238U series. This work, therefore, aims to determine the activity concentrations of 210Pb through radiochemical analysis, as well as, to evaluate some available techniques for the determination of 210Pb in the above-mentioned matrix. (author)

  8. Bioturbation depths, rates and processes in Massachusetts Bay sediments inferred from modeling of 210Pb and 239 + 240Pu profiles

    Crusius, John; Bothner, Michael H.; Sommerfield, Christopher K.

    2004-01-01

    Profiles of 210Pb and 239 + Pu from sediment cores collected throughout Massachusetts Bay (water depths of 36-192 m) are interpreted with the aid of a numerical sediment-mixing model to infer bioturbation depths, rates and processes. The nuclide data suggest extensive bioturbation to depths of 25-35 cm. Roughly half the cores have 210Pb and 239 + 240Pu profiles that decrease monotonically from the surface and are consistent with biodiffusive mixing. Bioturbation rates are reasonably well constrained by these profiles and vary from ~0.7 to ~40 cm2 yr-1. As a result of this extensive reworking, however, sediment ages cannot be accurately determined from these radionuclides and only upper limits on sedimentation rates (of ~0.3 cm yr-1) can be inferred. The other half of the radionuclide profiles are characterized by subsurface maxima in each nuclide, which cannot be reproduced by biodiffusive mixing models. A numerical model is used to demonstrate that mixing caused by organisms that feed at the sediment surface and defecate below the surface can cause the subsurface maxima, as suggested by previous work. The deep penetration depths of excess 210Pb and 239 + 240Pu suggest either that the organisms release material over a range of >15 cm depth or that biodiffusive mixing mediated by other organisms is occurring at depth. Additional constraints from surficial sediment 234Th data suggest that in this half of the cores, the vast majority of the present-day flux of recent, nuclide-bearing material to these core sites is transported over a timescale of a month or more to a depth of a few centimeters below the sediment surface. As a consequence of the complex mixing processes, surface sediments include material spanning a range of ages and will not accurately record recent changes in contaminant deposition.

  9. Inventory of 226Ra, 228Ra and 210Pb in marine sediments cores of Southwest Atlantic Ocean

    210Pb (22.3 y) is a radioactive isotope successfully applied as tracer of sediment dating of the last 100-150 years. The application of 226Ra and 228Ra as paleoceanographic tracers (half-lives of 1,600 y and 5.7 y, respectively) also gives some information of ocean's role in past climate change. In this work, it was analyzed 2 sediment cores collect at Southwest Atlantic Ocean. The sediments samples were freeze-dried and acid digested in microwave. It was carried out a radiochemical separation of 226Ra, 228Ra and 210Pb and performed a gross alpha and gross beta measurement of both precipitates Ba(Ra)SO4 and PbCrO4 in a low background gas-flow proportional counter. Activity concentrations of 226Ra ranged from 45 Bq kg-1 to 70 Bq kg-1 in NAP-62 and from 57 Bq kg-1 to 82 Bq kg-1 in NAP-63 samples. The concentration of 228Ra varied between 37 Bq kg-1 and 150 Bq kg-1 in NAP-62 and between 23 Bq kg-1 and 111 Bq kg-1 in NAP-63 samples. The concentration of total 210Pb ranged from 126 Bq kg-1 to 256 Bq kg-1 in NAP-62 and from 63 Bq kg-1 to 945 Bq kg-1 in NAP-63 samples. Results of 210Pbuns varied from 68 Bq kg-1 to 192 Bq kg-1 for NAP-62, while varied from <4.9 Bq kg-1 to 870 Bq kg-1 in NAP-63 profile. Increased values of 210Pbuns were found on the top of both NAP-62 and NAP- 63 sediment profile. (author)

  10. 210Pb/226Ra disequilibria in otoliths of blue grenadier, (Macruronus novaezelandiae); problems associated with radiometric aging

    Otoliths from blue grenadier (Macruronus novaezelandiae), which had been aged previously by annuli analysis, were analysed for the naturally occurring radionuclides 210Pb and 226Ra in an attempt to independently verify their age. It is concluded that the radiometric technique could not be applied to determine age because the results showed that 226Ra was not incorporated at a constant rate throughout the life of M. novaezelandiae. Uptake of 226Ra was greater in juveniles than in adult fish. This was probably due to the juvenile phase inhabiting inshore/estuarine waters. 20 refs., 1 tab., 2 figs

  11. Apparent discrepancy in contamination history of a sub-tropical estuary evaluated through {sup 210}Pb profile and chronostatigraphical markers

    Marques Junior, Aguinaldo N. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Biologia. Dept. de Biologia Marinha]. E-mail: amarques@vm.uff.br; Monna, Fabrice [Universite de Bourgogne, Dijon (France). Centre des Sciences de la Terre; Silva Filho, Emannoel V. da [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Quimica. Dept. de Geoquimica; Fernex, Francois E. [Universite de Nice, Valrose (France). Dept. des Sciences de la Terre; Simoes Filho, Fernando Lamego [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil)]. E-mail: flamego@ird.gov.br

    2005-07-01

    Heavy metal concentrations (Zn, Cd, Cu and Pb), lead stable isotopes ({sup 204}Pb, {sup 206}Pb, {sup 207}Pb, and {sup 208}Pb), and sediment chronology ({sup 210}Pb method) were determined in a core from Sepetiba Bay (southeastern coast of Brazil, 30 km west of Rio de Janeiro City). During last decades, this region has been modified by increase of industrial activities, population flows, and by human interventions in the watershed area of the bay. In particular, Zn and Cd emissions are well established to the bay, and inputs started during 1960 and 1970, respectively. The core was sampled in the more contaminated northern part of the bay, in the tidal flat in front of the Coroa Grande mangrove. This area is located near to the Sao Francisco Channel, which accounts for 86 % of the freshwater supply to the bay, and receive waters from the Paraiba do Sul River (another watershed) since 1950s. The proxies at the sediment core showed three successive events: at the depth of 50-52 cm, a marked change in the stable lead isotopic ratios; at 38-42 cm depth, the beginning of the Zn concentration upwards increase; and above 30 cm, relatively high Cd concentrations. Such records can easily be explained by the local metallurgic development history. However, sediment accumulation rates evaluated using these reference levels are higher than those calculated from the {sup 210}Pb profile by using either the Constant Initial Concentration (CIC) or the Constant Rate of Supply (CRS) models. One possible interpretation can be provided by local hydrodynamics, which has been strongly influenced by deposition of particles transported by runoff in the core site. The main source of these particles may be the mangrove flat that experimented enrichment of unsupported {sup 210}Pb by trapping it from the rain. A model, taking into account the exponential increase of the initial {sup 210}Pb activity observed in the core allows the calculated rates to fit well with those evaluated from the &apos

  12. The effect of different water managements on rice arsenic content in two arsenic-spiked soils

    Chang H. Y.

    2013-04-01

    Full Text Available Growing rice on arsenic (As-contaminated paddy fields may induce high As level grain production. In order to reduce the food contamination risk, the pot experiments containing two As-spiked aging soils and four water managements were conducted to evaluate the effects of water managements on rice As content. The results indicated that As concentration of Erlin soil solution was 10 to 20 times (210-520 μg/L higher than that of Pinchen soil solution (5-20 μg/L at early stage of experiment (0-60 days. Aerobic water treatment will decrease As level to 30-50% (108-220 μg/L of original As concentration in Erlin soil solution. Statistic results indicated that water management was effective to reduce the rice grain As level in Erlin soil. However, the management impact was not obvious in Pinchen soil, which may be attributed to high clay or free Fe and Al content in the soil. This study suggested that keeping soil under aerobic condition for 3 weeks before rice heading can reduce the risk of rice grown at the As-contamination soil.

  13. 210Pb-226Ra chronology reveals rapid growth rate of Madrepora oculata and Lophelia pertusa on world's largest cold-water coral reef

    N. Tisnérat-Laborde

    2012-03-01

    Full Text Available Here we show the use of the 210Pb-226Ra excess method to determine the growth rate of two corals from the world's largest known cold-water coral reef, Røst Reef, north of the Arctic circle off Norway. Colonies of each of the two species that build the reef, Lophelia pertusa and Madrepora oculata, were collected alive at 350 m depth using a submersible. Pb and Ra isotopes were measured along the major growth axis of both specimens using low level alpha and gamma spectrometry and trace element compositions were studied. 210Pb and 226Ra differ in the way they are incorporated into coral skeletons. Hence, to assess growth rates, we considered the exponential decrease of initially incorporated 210Pb, as well as the increase in 210Pb from the decay of 226Ra and contamination with 210Pb associated with Mn-Fe coatings that we were unable to remove completely from the oldest parts of the skeletons. 226Ra activity was similar in both coral species, so, assuming constant uptake of 210Pb through time, we used the 210Pb-226Ra chronology to calculate growth rates. The 45.5 cm long branch of M. oculata was 31 yr with an average linear growth rate of 14.4 ± 1.1 mm yr−1 (2.6 polyps per year. Despite cleaning, a correction for Mn-Fe oxide contamination was required for the oldest part of the colony; this correction corroborated our radiocarbon date of 40 yr and a mean growth rate of 2 polyps yr−1. This rate is similar to the one obtained in aquarium experiments under optimal growth conditions. For the 80 cm-long L. pertusa colony, metal-oxide contamination remained in both the middle and basal part of the coral skeleton despite cleaning, inhibiting similar age and growth rate estimates. The youngest part of the colony was free of metal oxides and this 15 cm section had an estimated a growth rate of 8 mm yr−1, with high uncertainty (~1 polyp every two to three years. We are less certain of this 210Pb growth rate estimate which is within the lowermost

  14. 210Pb-226Ra chronology reveals rapid growth rate of Madrepora oculata and Lophelia pertusa on world's largest cold-water coral reef

    Sabatier, P.; Reyss, J.-L.; Hall-Spencer, J. M.; Colin, C.; Frank, N.; Tisnérat-Laborde, N.; Bordier, L.; Douville, E.

    2012-03-01

    Here we show the use of the 210Pb-226Ra excess method to determine the growth rate of two corals from the world's largest known cold-water coral reef, Røst Reef, north of the Arctic circle off Norway. Colonies of each of the two species that build the reef, Lophelia pertusa and Madrepora oculata, were collected alive at 350 m depth using a submersible. Pb and Ra isotopes were measured along the major growth axis of both specimens using low level alpha and gamma spectrometry and trace element compositions were studied. 210Pb and 226Ra differ in the way they are incorporated into coral skeletons. Hence, to assess growth rates, we considered the exponential decrease of initially incorporated 210Pb, as well as the increase in 210Pb from the decay of 226Ra and contamination with 210Pb associated with Mn-Fe coatings that we were unable to remove completely from the oldest parts of the skeletons. 226Ra activity was similar in both coral species, so, assuming constant uptake of 210Pb through time, we used the 210Pb-226Ra chronology to calculate growth rates. The 45.5 cm long branch of M. oculata was 31 yr with an average linear growth rate of 14.4 ± 1.1 mm yr-1 (2.6 polyps per year). Despite cleaning, a correction for Mn-Fe oxide contamination was required for the oldest part of the colony; this correction corroborated our radiocarbon date of 40 yr and a mean growth rate of 2 polyps yr-1. This rate is similar to the one obtained in aquarium experiments under optimal growth conditions. For the 80 cm-long L. pertusa colony, metal-oxide contamination remained in both the middle and basal part of the coral skeleton despite cleaning, inhibiting similar age and growth rate estimates. The youngest part of the colony was free of metal oxides and this 15 cm section had an estimated a growth rate of 8 mm yr-1, with high uncertainty (~1 polyp every two to three years). We are less certain of this 210Pb growth rate estimate which is within the lowermost ranges of previous growth

  15. Distribution of some chemical elements between dissolved and particulate phases in the ocean. Research period: August 1, 1975--July 31, 1976. [Fallout /sup 210/Po and /sup 210/Pb diffusion in oceans

    1976-01-01

    Progress is reported on studies on the distributions of fallout /sup 210/Pb and /sup 210/Po in dissolved and particulate states in the Gulf of Maine and a transect of the equatorial North Atlantic Ocean. The ratio of /sup 210/Pb//sup 226/Ra and /sup 210/Po//sup 210/Pb in seawater and suspended particulate matter in samples collected from 10 stations in the tropical and eastern North Atlantic and two stations in the Pacific was also determined. (CH)

  16. Assessment of committed effective dose due to the ingestion of 210Po and 210Pb in consumed Lebanese fish affected by a phosphate fertilizer plant

    Ingestion of radionuclides through seafood intake is a one of the sources contributing to the internal effective dose in the human organism. In order to evaluate the internal exposure and potential risks due to 210Po and 210Pb associated with fish consumption, these radionuclides were measured in commonly consumed fish species from a clean area and an area subjected to the impact of a Lebanese phosphate fertilizer plant. The highest concentration of 210Pb was 98.7 Bq/kg fresh weight while 210Po activity concentrations varied from 3.6 Bq/kg to 140 Bq/kg. A supplementary radiation exposure was detected; the highest committed effective dose due to 210Po and 210Pb was found to be 1110 μSv/y and 450 μSv/y, respectively. Moreover, the average mortality and morbidity risks due to the fish consuming were estimated. - Highlights: • Enrichment in 210Po and 210Pb in fish affected by a phosphate fertilizer plant. • Significant human exposure associated with the ingestion of fish. • Estimation of potential risks due to 210Po and 210Pb via fish consumption

  17. Analysis of the gamma spectrometry 210Pb radioisotope in river bottom sediments of the hydrographic sub-basins around the UTM-Caldas

    The uranium mine of Caldas, currently named Ore Treatment Unit (UTM-Caldas), is sited at the Pocos de Caldas Plateau (Minas Gerais State) and was the first uranium mineral-industrial complex in Brazil. It has been installed since 1982 and now it is under decommissioning process. Taking into account the potential sources of contamination and the assessment of the impact of the mine, based on the presence of radionuclides from the radioactive decay series of natural 238U, the aim of the article is to present the distribution of 210Pb in the stream bottom sediments of the study area that consists of the Taquari watershed, sub-divided by its three major sub-basins: Consulta stream, Soberbo stream and Taquari river. The radionuclide activity concentrations were measured in sediment samples that were collected in twelve collecting points, during four sampling campaigns, carried out in the dry and rainy seasons of 2010 and 2011. The results of the 210Pb concentration activity were obtained by gamma spectrometry performed in both high and low energy CANBERRA detectors. The results point out that the UTM-Caldas is influencing on the bottom sediment distribution of 210Pb activity in its neighborhood. However, a more detailed study should be done in order to identify if there is another source of 210Pb in the study area, such as a geogenic anomaly, that may contributing to the local increment of 210Pb activity. (author)

  18. Recent history of sediment dynamics in Lake Toro and applicability of 210Pb dating in a highly disturbed catchment in northern Japan

    Ahn, Young Sang; Nakamura, Futoshi; Chun, Kun Woo

    2010-01-01

    Sediment dynamics for the last 300 years in Lake Toro and the applicability of 210Pb dating (CIC and CRS models) are evaluated. The lake sedimentation and sediment yield were determined by 137Cs (in 1963) and two tephra layers (Ko-c2 in 1694 and Ta-a in 1739). The average sediment yields for initial development periods of catchments were 13.0-14.1 t km - 2 yr - 1 until 1963 and increased to 30.5 t km - 2 yr - 1 after 1963 because of the conversion of floodplain and upland forests to cultivated lands. In particular, the western zone of the lake near the conjunction with the Kushiro River had a high sedimentation rate, which is attributable to sediment inflow back from the Kushiro River during floods. The CIC model was not applicable because of fluctuations in the 210Pb profiles since 1963. The CRS model agrees with the 137Cs dating in all sites except for one site close to the Kushiro River inflow. 210Pb dating may contain considerable errors where the 210Pb concentration profile and flux are perturbed by floodwater from the Kushiro River, which contains low levels of 210Pb.

  19. Analysis of the gamma spectrometry {sup 210}Pb radioisotope in river bottom sediments of the hydrographic sub-basins around the UTM-Caldas

    Dutra, Pedro H.; Carvalho Filho, Carlos A.; Moreira, Rubens M.; Menezes, Maria Angela B.C.; Oliveira, Aline F.G. de, E-mail: pedrohenrique.dutra@gmail.com [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Silva, Nivaldo C., E-mail: ncsilva@cnen.gov.br [Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas; Viana, Valquiria F.L., E-mail: valquiria.flviana@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Instituto de Ciencias Biologicas

    2015-07-01

    The uranium mine of Caldas, currently named Ore Treatment Unit (UTM-Caldas), is sited at the Pocos de Caldas Plateau (Minas Gerais State) and was the first uranium mineral-industrial complex in Brazil. It has been installed since 1982 and now it is under decommissioning process. Taking into account the potential sources of contamination and the assessment of the impact of the mine, based on the presence of radionuclides from the radioactive decay series of natural {sup 238}U, the aim of the article is to present the distribution of {sup 210}Pb in the stream bottom sediments of the study area that consists of the Taquari watershed, sub-divided by its three major sub-basins: Consulta stream, Soberbo stream and Taquari river. The radionuclide activity concentrations were measured in sediment samples that were collected in twelve collecting points, during four sampling campaigns, carried out in the dry and rainy seasons of 2010 and 2011. The results of the {sup 210}Pb concentration activity were obtained by gamma spectrometry performed in both high and low energy CANBERRA detectors. The results point out that the UTM-Caldas is influencing on the bottom sediment distribution of {sup 210}Pb activity in its neighborhood. However, a more detailed study should be done in order to identify if there is another source of {sup 210}Pb in the study area, such as a geogenic anomaly, that may contributing to the local increment of {sup 210}Pb activity. (author)

  20. Sediment Radiochronology Using Coastal 210Pb: Model, Validation and Applications (Spanish Edition)

    techniques in support of integrated coastal zone. This project is aligned with the objectives of the IAEA in the environment, including 'facilitating the sustainable use of natural resources where isotopes can improve understanding of natural systems that allow, for example, prediction of future global trends from the past and overall assessment of resources'. The project involves Colombia, Costa Rica, Cuba, Guatemala, Haiti, Honduras, Jamaica, Mexico, Nicaragua, Panama, Dominican Republic and Venezuela, with the support of the Centre for Energy, Environment and Technology (CIEMAT, Spain), the Institute Research for Development (IRD, France) and in collaboration with the Regional Coordinating Unit of the Caribbean of the United Nations Program for the Environment (UNEP-CAR/RCU). It is expected that the project results will improve the commitment of Member States and regional organizations in activities to protect the environment now and in the future. Through the regional laboratory training and a better understanding of coastal ecosystems from baseline studies and historical reconstruction of pollution levels, a strong network of laboratories with improved capabilities will be able to continue to contribute to the sustainable management of Caribbean Sea. Methodologies are being developed for monitoring and management. The results will be disseminated to the scientific community, policy makers and society, in addition to international organizations such as UNEP and the Association of Caribbean States. The objective of the results is to support integrated management of the coastal zone. One of the main methodologies of this project is the use of coastal sediments as records of environmental change, including pollution. Since most of the changes have occurred in the region during the twentieth century, the best chronology is provided by 210Pb, a natural radioactive element with a half-life of about 20 years, allowing sediments dating to about 100 years of seniority. Although

  1. The effect of 210Pb and stable lead on the induction of mouthpart deformities in chironomid larvae

    To determine whether mouthpart deformities in chironomid larvae from Port Hope Harbour, Ontario, are the result of exposure to ionizing radiation or heavy metals in the sediment, Chironomus tentans larvae were exposed in the laboratory to concentrations of 210Pb and stable lead representative of contaminant levels in the harbour. Exposure to 100, 1000, and 2000 Bq 210Pb·g-1 dry sediment had no effect on the survival, growth of the larvae or frequency of deformities. Likewise, exposure to 0.5 and 5.0 mg lead·g-1 dry sediment had no effect on the larvae, but exposure to 35.0 mg lead·g-1 dry sediment resulted in 100% mortality of the larvae. These results indicate that the observed mouthpart deformities in chironomid larvae in Port Hope Harbour are not the result of radiation exposure. They also indicate that heavy metals (lead) may be having an impact on the population. (author). 28 refs., 9 tabs., 4 figs

  2. 210Pb and 210Po in tobacco - with a special focus on estimating the doses of 210Po to man

    Inhalation of tobacco smoke is ranked second to food as a source of 210Pb and 210Po exposure to man. assay of 210Pb and 210Po in commercially available tobacco collected from many countries have been carried out to assess the potential risk from 210Po present in tobacco. The range of 210Po contained in the tobacco grands varied from 10.08 to 15.0 mBq/tob or 13.0 to 20.1 mBq/g and the mean was 11.6 mBq/tob or 15.4 mBq/g. During the International Standard Smoking process about 50% of 210Po present in tobaccos was transferred into the smoke and the other 50% remained in the ash and butt. About 10% of the total 210Po of tobacco was inhaled by smoke through mainstream smoke. One pack-a-day smoker inhaled 24 mBq of 210Po per day through smoking and the annual inhalation was 8.8 Bq. The risk of mortality from lung cancer caused by 210Po in tobaccos was 18 per million persons for the above model. (author) 6 refs.; 1 fig.; 4 tabs

  3. Determination of {sup 226}Ra, {sup 228}Ra, and {sup 210}Pb in mushroom from a naturally high radioactive region

    Rosa, Mychelle M.L.; Custodio, Luis Gustavo; Cheberle, Luan T.V.; Taddei, Maria Helena T., E-mail: mychelle@cnen.gov.br, E-mail: lgcustodio@hotmail.com, E-mail: lt.cheberle@bol.com.br, E-mail: mhtaddei@cnen.gov.br [Comissao Nacional de Energia Nuclear (LAPOC/CNEN-MG), Pocos de Caldas, MG (Brazil). Laboratorio de Pocos de Caldas; Maihara, Vera A., E-mail: vmaihara@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (CNEN/IPEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    Many studies have shown that mushrooms are organisms which efficiently accumulate radionuclides and can be used as indicators of environmental contamination and ecosystem quality. The Pocos de Caldas plateau, in Minas Gerais, is a region that has elevated natural radioactivity due to the presence of radiological anomalies of volcanic origin. Seventy areas of radioactive anomalies have been identified in this region. From the radiological point of view the determination of {sup 226}Ra, {sup 228}Ra, and {sup 210}Pb is relevant because they are decay products of the natural series of {sup 238}U and {sup 232}Th, mainly responsible for natural radioactive exposures of man. The present paper is part of a broader study conducted in the Pocos de Caldas plateau, in which the concentration activities of {sup 226}Ra, {sup 228}Ra, and {sup 210}Pb in mushroom samples were determined. The mushrooms were collected at different points of the plateau under the influence of radioactive anomalies and away from the influence of anomalies. From statistical studies a correlation between the accumulation of radionuclides in mushrooms and anomalies was established and it was possible to confirm the efficiency that the mushrooms present as environmental contamination indicators. (author)

  4. Determination of 226Ra, 228Ra, and 210Pb in mushroom from a naturally high radioactive region

    Many studies have shown that mushrooms are organisms which efficiently accumulate radionuclides and can be used as indicators of environmental contamination and ecosystem quality. The Pocos de Caldas plateau, in Minas Gerais, is a region that has elevated natural radioactivity due to the presence of radiological anomalies of volcanic origin. Seventy areas of radioactive anomalies have been identified in this region. From the radiological point of view the determination of 226Ra, 228Ra, and 210Pb is relevant because they are decay products of the natural series of 238U and 232Th, mainly responsible for natural radioactive exposures of man. The present paper is part of a broader study conducted in the Pocos de Caldas plateau, in which the concentration activities of 226Ra, 228Ra, and 210Pb in mushroom samples were determined. The mushrooms were collected at different points of the plateau under the influence of radioactive anomalies and away from the influence of anomalies. From statistical studies a correlation between the accumulation of radionuclides in mushrooms and anomalies was established and it was possible to confirm the efficiency that the mushrooms present as environmental contamination indicators. (author)

  5. 14C and 210Pb in NE Atlantic sediments: evidence of biological reworking in the context of radioactive waste disposal

    Scavenging by the seabed and sediments in the deep ocean may have a significant effect on the removal of artificial radionuclides released in radioactive waste disposal operations. Biological activity in the upper layers of the sediment column will enhance the rate of removal for those particle-reactive radionuclides with a short half-life relative to the turnover time of the upper mixed layer. For longer-lived radionuclides the rate of sediment accumulation will determine the ultimate rate of removal. The rate of sediment accumulation and extent of biological mixing of a deep-sea sediment from three areas of the NE Atlantic Ocean have been investigated using 14C and 210Pb data. For 14C, box cores from the Iberia Abyssal Plain, Madeira Abyssal Plain and from the NEA low-level radioactive waste dumpsite yielded sedimentation rates in the range 0.8 to 2.2 cm ky-1 over the upper 16-25 cm. Continuous particle mixing appears to be taking place to a depth of 4 to 6 cm below the present sediment-water interface. Closely spaced vertical sampling of core 161-2 for 210Pb allowed a biodiffusion coefficient (Dsub(B)) to be calculated (4 x 10-9 cm2s-1). (author)

  6. Study of sedimentation rates in the coastal areas of manila bay using /sup 210/Pb-dating technique

    The presence of toxic Harmful Algal Blooms (HAB) has been reported in more than 20 areas in the Philippine after its first record occurrence in 1983. The HAB causing organism (Pyrodinium bahamense var compressum) normally produces a temporary and resting cyst during its life cycle. These cysts, which are deposited in the sediment column of the affected Bay, may play an important role in initiating the next episode of toxic bloom. To provide an age control to the cyst, produced by the causative organism, several cores have been collected from the Bay and analyzed for /sup 210/Pb using alpha spectrometry. The surface activity of these sediments ranged from 22 plus minus 4 to 110 plus minus 8 Bqkg/sup -1/ with an average value of 68.3 plus minus 38 Bqkg/sup -1/. The derived /sup 210/Pb vertical profile indicates a marked increase in sedimentation rate during the last ten years in the deeper portions of the bay. Higher sedimentation rates about 1 cm y/sup -l/ have been observed in the northern and western parts of the Manila Bay. Results indicate that the sedimentation process occurring in the Bay would require subsurface cyst concentration analysis in evaluating the potential of an area to act as seed-bed. (author)

  7. Leachability of 226Ra from spiked soil as a function of time

    The bioavailability of 226Ra for plant uptake may be dependent on its solubility from the soil components. Solubility of radium from soil may change with time due to chemical and physical binding. A laboratory study was designed to provide data on the water leachable fraction of 226Ra from spiked soil as a function of time. A decreasing trend in the percent leachable fraction was observed over time. The data was modeled by non-linear regression to be a decreasing exponential to a constant value. This information may be helpful in providing an understanding of a similar trend observed in plant uptake studies. The value for the available amount of radium determined in this investigation may help to provide a more meaningful measurement of concentration ratios in plants. 22 references, 3 figures, 5 tables

  8. A sequential and fast method for low level of 226Ra , 228Ra, 210Pb e 210Po in mine effluents and uranium processing plant

    Due to biological risk and long half lives, the radionuclides 228Ra, 226Ra, 210Pb and 210Po should be frequently monitored to check for any environmental contamination around mines and uranium plants. Currently, the methods used for the determination of these radionuclides take about thirty days to reach the radioactive equilibrium of the 210Pb and 226Ra daughter's. The evaluation of effluent discharges and leakage of deposits to water bodies in monitoring programs, require quick answers to implement corrective measures. Thereby fast determination methods must be implemented. This work presents a fast and sequential method to, in three days, determine accurately and sensitively, 226Ra, 228Ra, 210Pb, 210Po, in water and effluent samples

  9. Calibration of an HPGe detector and self-attenuation correction for 210Pb: Verification by alpha spectrometry of 210Po in environmental samples

    Saïdou; Bochud, François; Laedermann, Jean-Pascal; Buchillier, Thierry; Njock Moïse, Kwato; Froidevaux, Pascal

    2007-08-01

    In this work the calibration of an HPGe detector for 210Pb measurement is realised by a liquid standard source and the determination of this radionuclide in solid environmental samples by gamma spectrometry takes into account a correction factor for self-attenuation of its 46.5 keV line. Experimental, theoretical and Monte Carlo investigations are undertaken to evaluate self-attenuation for cylindrical sample geometry. To validate this correction factor, 210Po (at equilibrium with 210Pb) alpha spectrometry procedure using microwave acid digestion under pressure is developed and proposed. The different self-attenuation correction methods are in coherence, and corrected 210Pb activities are in good agreement with the results of 210Po. Finally, self-attenuation corrections are proposed for environmental solid samples whose density ranges between 0.8 and 1.4 g/cm 3 and whose mass attenuation coefficient is around 0.4 cm 2/g.

  10. Methodological issues about techniques for the spiking of standard OECD soil with nanoparticles: evidence of different behaviours

    Miglietta, Maria Lucia, E-mail: mara.miglietta@enea.it; Rametta, Gabriella; Manzo, Sonia; Salluzzo, Antonio; Rimauro, Juri; Francia, Girolamo Di [ENEA, Portici Technical Unit, C.R. Portici (Italy)

    2015-07-15

    The aim of this study is to investigate at what extent the results of standard nanoparticle (NP) toxicity testing methodologies are affected by the different exposure procedures on soil organisms. In this view, differences in physicochemical properties of ZnO NPs (<100 nm), ZnO bulk (<200 nm) and ionic Zinc (ZnCl{sub 2}) and their ecotoxicological potential toward Lepidium sativum were investigated with respect to three different spiking methods. Results show that the spiking procedures give homogeneous distribution of the testing nanomaterial in soil but the physicochemical and ecotoxicological properties of the testing species differ according to the spiking procedure. Dry spiking produced the highest ZnO solubility whereas spiking through dispersions of ZnO in water and in aqueous soil extracts produced the lowest. At the same time, the ecotoxic effects showed different trends with regard to the spiking route. The need for a definition of agreed methods concerning the NP spiking procedures is, therefore, urgent.

  11. Methodological issues about techniques for the spiking of standard OECD soil with nanoparticles: evidence of different behaviours

    The aim of this study is to investigate at what extent the results of standard nanoparticle (NP) toxicity testing methodologies are affected by the different exposure procedures on soil organisms. In this view, differences in physicochemical properties of ZnO NPs (<100 nm), ZnO bulk (<200 nm) and ionic Zinc (ZnCl2) and their ecotoxicological potential toward Lepidium sativum were investigated with respect to three different spiking methods. Results show that the spiking procedures give homogeneous distribution of the testing nanomaterial in soil but the physicochemical and ecotoxicological properties of the testing species differ according to the spiking procedure. Dry spiking produced the highest ZnO solubility whereas spiking through dispersions of ZnO in water and in aqueous soil extracts produced the lowest. At the same time, the ecotoxic effects showed different trends with regard to the spiking route. The need for a definition of agreed methods concerning the NP spiking procedures is, therefore, urgent

  12. Biomonitoring of {sup 210}Po and {sup 210}Pb using lichens and mosses around coal-fired power plants in Western Turkey

    Sert, Emel, E-mail: emel.sert@mail.ege.edu.tr [Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir (Turkey); Ugur, Aysun, E-mail: aysun.ugur@ege.edu.tr [Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir (Turkey); Ozden, Banu, E-mail: banu.ozden@ege.edu.tr [Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir (Turkey); Sac, Mueslim Murat, E-mail: muslum.murat.sac@ege.edu.tr [Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir (Turkey); Camgoez, Berkay, E-mail: berkay.camgoz@ege.edu.tr [Ege University, Institute of Nuclear Sciences, 35100 Bornova, Izmir (Turkey)

    2011-06-15

    Mosses and lichens are useful biological indicators of environmental contamination for a variety of metals and radionuclides of both natural and artificial origin. These plants lack a well-developed root system and rely largely on atmospheric deposition for nourishment. Therefore in the study, different lichens (Cladonia convoluta, Cladonia foliacea) and mosses (Homalothecium sericeum, Hypnum lacunosum, Hypnum cupressiforme, Tortella tortuosa, Didymodon acutus, Syntrichia ruralis, Syntrichia intermedia, Pterogonium graciale, Isothecium alopecuroides, Pleurochatae squarrosa) were collected around the Yatagan (Mugla), Soma (Manisa), Seyitoemer - Tuncbilek (Kuetahya) coal-fired power plants and investigated for potential use as biomonitors for {sup 210}Po and {sup 210}Pb deposition. While the activity concentrations of {sup 210}Po and {sup 210}Pb in lichens are in the ranges of 151 {+-} 7-593 {+-} 21 and 97 {+-} 5-364 {+-} 13 Bq kg{sup -1}, for mosses the ranges for {sup 210}Po and {sup 210}Pb are 124 {+-} 5-1125 {+-} 38 and 113 {+-} 4-490 {+-} 17 Bq kg{sup -1}, respectively. In the study, the moss samples were observed to accumulate more {sup 210}Po and {sup 210}Pb compared to lichens. While the most suitable biomonitor was a moss species (H. lacunosum) for Yatagan (Mugla), it was another moss species (S. intermedia) for Soma (Manisa) and Seyitoemer - Tuncbilek (Kuetahya) sites. {sup 210}Po concentrations were found higher than {sup 210}Pb concentrations at the all sampling stations. - Highlights: > Lichens and mosses have been used as biomonitors of 210Po and 210Pb deposition. > The morphology of lichens and mosses does not vary with seasons. > Lichens and mosses retain and accumulate pollutants deposited from the atmosphere. > Canopy is an important factor causing differences in the concentrations of radionuclides.

  13. Particle-reactive radionuclides (234Th, 210Pb, 210 as tracers for the estimation of export production in the South China Sea

    P. H. Santschi

    2011-12-01

    Full Text Available The time-series station, SEATS (18° N, 116° E in the South China Sea was visited six times during October 2006–December 2008 to carry out seawater sampling and floating trap deployments for the determination of distributions and fluxes of POC, PIC, PN, 234Th, 210Pb, and 210Po in the upper 200 m of the water column. Radionuclide deficiencies resulted in removal fluxes from the euphotic layer of 1.1×103–1.8×103 dpm m−2d−1 and 7.1–40.2 dpm m−2d−1 for 234Th and 210Po, respectively. Due to atmospheric input, an excess of 210Pb relative to 226Ra is commonly observed in the upper water column. Sinking fluxes of total mass, POC, PIC, PN, 234Th, 210Pb, and 210Po measured at the euphotic depth were low in summer-fall and high in winter-spring, reflecting the seasonal variability of biological pumping. Excluding the suspiciously low primary productivity data point in July 2007, a relatively high e-ratio of 0.28–0.69 was estimated by the ratio of the POC flux at the euphotic depth and the integrated primary productivity. The ratios of 234Th, 210Pb, and 210Po to organic carbon, inorganic carbon, and nitrogen in the sinking particles were combined with the disequilibria of 234Th–238U, 210Pb–226Ra, and 210Po–210Pb to estimate export fluxes of POC, PIC, and PN from the euphotic layer. Compared with measured fluxes by the sediment trap and estimated fluxes by other approaches, it is concluded that the export production in the South China Sea, ranging from 1.8 to 21.3 mmol-C m−2d−1, can be reasonably estimated using 234Th, 210Pb, and 210Po as carbon proxies.

  14. Evaluation of two extraction procedures for the recovery of organic chemicals from spiked soils

    The objective of this study was to evaluate the efficiencies of the automatic Soxtec and US EPA SW846 Soxhlet soil extraction methods. In phases one and two of the experiment, extractions were performed on silicon dioxide matrices and silt-loam soils spiked with benz(a)pyrene, pentachlorophenol, and naphthalene at three concentration levels. Each test sample contained either an individual chemical or a 1:1:1 mixture of all three chemicals. Phase three consisted of extractions performed on a silt-loam soil spiked with a coal tar complex mixture. Soxtec samples were sequentially extracted with dichloromethane and methanol while Soxhlet samples were extracted with dichloromethane. Gas chromatographic results obtained from sample extract analysis were used to calculate percent recoveries of the chemicals. The recoveries of benz(a)pyrene and pentachlorophenol in the Soxtec procedure ranged from 55--88% and 49--88%, respectively. For the Soxhlet method, the recoveries ranges from 46--73% and 52--87%, respectively. Complex mixture recoveries ranged from 50--60% for both procedures. The mutagenic potentials of the solvent extracts were evaluated using Salmonella typhimurium strain TA98 with and without metabolic activation

  15. Assessment of the potential impact of the phosphate industry along the Syrian Coast by evaluating 210Po and 210Pb levels in sediment, seawater and selected marine organisms

    Phosphate industry is considered to be one of the potential sources of natural radionuclides in Syrian environment. Most of the phosphate ore is exported in large quantities via one of the main Syrian ports (Tartous) situated on the east coast of the Mediterranean Sea (34 54 North , 35 52 East). The impact of the loading cargoes on the marine environment has been evaluated. 210Po and 210Pb in seawater, sediment and marine organisms have been determined. Results have shown a significant enhancement of these two radionuclides in sediment and surface water inside the port area. The highest 210Po and 210Pb concentrations observed in sediment were found to be 170 Bq.kg-1and 64 Bq.kg-1 respectively. While, 210Pb and 210Po concentrations in surface water ranged from 5 to 20 m Bq.l-1 and 0.93 to 3.23 m Bq.l-1. In addition, other naturally occurring radionuclides were also determined in the collected sediment samples and relatively higher values (226Ra = 33.2 Bq.kg-1 and 234Th = 88 Bq.kg-1) were observed for those samples collected from inside the port. However, the effect of loading cargoes on the near marine environment was found to be mainly related to wind direction where air particulate carrying radioactivity either being blown to lands or sea. Moreover, comparable values of 210Po and 210Pb for all marine organisms (algae, crab and fish) have been observed and it is not recommended to use these organisms for evaluating the effect of phosphate industry on marine environment. This is due to the fact that marine organisms accumulate 210Po and 210Pb in their body. Two core samples were also collected in order to investigate the history of pollution in the port. Results have shown a complex relation for unsupported 210Pb with depth, where the constant supply dating method can not be applied. This is due to the fact that two sources for unsupported 210Pb being observed in the port area; viz. radon gas and phosphate dust carrying radioactivity including 210Pb. However, depth

  16. The particulate {sup 7}Be/{sup 210}Pb{sub xs} and {sup 234}Th/{sup 210}Pb{sub xs} activity ratios as tracers for tidal-to-seasonal particle dynamics in the Gironde estuary (France): Implications for the budget of particle-associated contaminants

    Saari, Hanna-Kaisa [Universite de Bordeaux, UMR5805 EPOC, F-33405 Talence Cedex (France); Schmidt, Sabine, E-mail: s.schmidt@epoc.u-bordeaux1.fr [CNRS, UMR5805 EPOC, F-33405 Talence Cedex (France); Castaing, Patrice; Blanc, Gerard [Universite de Bordeaux, UMR5805 EPOC, F-33405 Talence Cedex (France); Sautour, Benoit [Universite de Bordeaux, UMR5805 EPOC, Station Marine d' Arcachon, F-33120 Arcachon (France); Masson, Olivier [IRSN, BP 3, 13115 Saint Paul Lez Durance (France); Cochran, J. Kirk [Marine Sciences Research Center, School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794-5000 (United States)

    2010-09-15

    The short-lived natural radionuclides {sup 7}Be (T{sub 1/2} = 53 days), {sup 234}Th{sub xs} (T{sub 1/2} = 24.1 days) and {sup 210}Pb{sub xs} (T{sub 1/2} = 22.3 years), i.e. {sup 234}Th and {sup 210}Pb in excesses of that supported within particles by the decay of their parent isotopes, were analysed in suspended particulate matter (SPM) to study the particle dynamics in the Gironde fluvial estuarine system (France), strongly impacted by heavy metal pollution. From surveys of this land-ocean interface in 2006 and 2007, we established a times series of these radioisotopes and of their activity ratios ({sup 7}Be/{sup 210}Pb{sub xs} and {sup 234}Th/{sup 210}Pb{sub xs} ARs) in particles sampled under different hydrological conditions. The particulate {sup 7}Be/{sup 210}Pb{sub xs} AR varies along the fluvial estuarine system mainly due to variations in {sup 7}Be activities, controlled by riverine, oceanic and atmospheric inputs and by resuspension of old {sup 7}Be-deficient sediments. These processes vary with river discharge, tidal cycle and season. Therefore, seasonal particle transport processes can be described using variations of the SPM {sup 7}Be/{sup 210}Pb{sub xs} ARs. During high river discharge, the SPM {sup 7}Be/{sup 210}Pb{sub x} ARs decrease from river to the ocean. The turbidity maximum zone (TMZ) is dispersed and the particles, and the associated contaminants, are rapidly transported from river to coastal waters, without significant retention within the TMZ. During low river discharge, the TMZ intrudes into the fluvial estuary, and the lowest {sup 7}Be/{sup 210}Pb{sub x} ARs are observed there due to resuspension of {sup 7}Be-deficient sediments. Away from the TMZ, from the middle to lower estuary, SPM {sup 7}Be/{sup 210}Pb{sub x} ARs increase, indicating that the particles have been recently tagged with {sup 7}Be. We explain this trend as being caused by marine input of dissolved radionuclides, as traced by SPM {sup 234}Th/{sup 210}Pb{sub xs} ARs

  17. Rate of sedimentation in the Yamuna river around Delhi using the sup(226)Ra-sup(210)Pb method

    Subramanian, V.; Sitasaward, R.; Joshi, L.U.

    1985-07-01

    For six sediment cores collected from Yamuna river (tributary of Ganges) around Delhi, rate of sedimentation was determined by the sup(226)Ra-sup(210)Pb method. While an average rate of 42 mm/y is obtained, there are variations core to core. A clear-cut downstream increase in the rate from 5 mm/y when the river enters Delhi, to 80 mm/y when it leaves Delhi indicates solid waste contribution from the urban areas. The sediment flux of 4000 mg/cmsup(2)/y is not balanced by the calculated rate of erosion (40 tonnes/kmsup(2)/y) in the river. Thus, much of the sediment flux is of local origin.

  18. Determination of 90Sr and 210Pb in sludge samples using a LOV-MSFIA system and liquid scintillation counting

    There has been increasing interest recently in the capacity of water treatment plants to concentrate and eliminate radionuclides from raw water. As the normal operation in these plants generates high quantities of sludge, which can be considered a naturally occurring radioactive material, it is important to gather information about its radiological content. Therefore, in order to determine the activity values of two radioactive beta emitters with minimal sample manipulation, an automated lab-on-valve and multisyringe flow injection system has been developed to achieve the sequential preconcentration and separation of 90Sr and 210Pb using an extraction chromatographic resin (Sr-spec). Activities of both isotopes were measured by liquid scintillation counting (LSC). The developed method was validated by analyzing three samples from three different intercomparison exercises and good Z-score values (between 0.1 and 1) and trueness values (between 10% and 17%) were obtained. The method was then also satisfactorily applied to sludge samples taken from a Spanish drinking water treatment plant which treats water from the Ebro River. The proposed method offers advantages over existing methods as it allows the sequential separation of both isotopes, simply by changing the elution conditions and using a semi-automated approach. Therefore, the method is less time consuming and environmentally friendly. - Highlights: • Flow system methodologies have been developed for the sequential separation of 90Sr and 210Pb. • Two radioactive beta emitters are determined with minimum sample manipulation. • Sludge samples from DWTP which were considered to be NORM samples have been analyzed. • Activities of both isotopes have been measured by liquid scintillation counting

  19. Assessment of exposure of uranium miners to radon progeny using in vivo measurement of 210Pb in bone

    Epidemiological studies of lung cancer incidence among uranium miners from various populations around the world have shown a significant variability in the relative risk per unit exposure - a range of a factor of 30. A significant fraction of the uncertainty associated with these risk coefficients may be due to differences in the methods and quality of data used in calculating cumulative exposures, in Working Level Months (WLM), for the various miner populations. We hypothesize that in vivo measurement of 210Pb, a long-lived radon decay product, retained in bone will provide a better measure of the exposure of individual miners to radon and progeny during their mining careers. To accomplish these in vivo measurements, the Lovelace Respiratory Research Institute (LRRI) In Vivo Bioassay Facility (IVBF) was modified to optimize a counting geometry for measuring 210Pb in the skull. Six phoswich detectors (12.7 cm diameter) were positioned about the head of a reclining subject (one posterior, one anterior, and four on the sides of the head), and photon emission from the skull was measured using anticoincidence multichannel analysis electronics. To date, we have analyzed the in vivo measurement data from about 90 former uranium miners from the Grants, New Mexico (NM), mining district. The recorded WLM exposures for each uranium miner (data from the UNM epidemiological data base) were compared with a WLM exposure calculated using a Pb biokinetic model coupled to the ICRP Publication 66 respiratory tract dosimetry model. The analyses show that the independent measures of exposure are statistically correlated but vary greatly among individual values. (author)

  20. Effects of arsenic and cadmium on bioaccessibility of lead in spiked soils assessed by Unified BARGE Method.

    Xia, Qing; Peng, Cheng; Lamb, Dane; Kader, Mohammed; Mallavarapu, Megharaj; Naidu, Ravi; Ng, Jack C

    2016-07-01

    The bioaccessibility of lead (Pb) in contaminated soils has been extensively studied, including the influence of soil properties on Pb bioaccessibility. However, little is known about the effects of other metals/metalloid, such as arsenic (As), cadmium (Cd) on the bioaccessibility of Pb, i.e. whether As or Cd could increase or decrease the solubility of Pb in human gastrointestinal tract when Pb-contaminated soil and As-contaminated (or Cd-contaminated) soil are ingested simultaneously. Furthermore, it is far from clear that if soil property could make a difference to these effects. In this study, seven types of soils were collected in Australia and spiked with As, Cd or Pb. Gastric bioaccessibility of Pb ranged from 44 ± 0.9% to 100 ± 6.7% whilst intestinal bioaccessibility dropped to 1 ± 0.2% to 36 ± 1.7%. Statistical analysis shows total Pb in soil was the most significant controller for bioaccessible Pb. Effects of As and Cd on the bioaccessibility of Pb in simulated human digestive system were studied by mixing As-spiked soil (or Cd-spiked soil) with Pb-spiked soil of the same type during bioaccessibility test. Results reveal that neither As nor Cd had impact on Pb bioaccessibility, which indicates when As, Cd and Pb aged in soils separately, they may behave independently in the bioaccessibility measuring system. This finding can be part of evidence to assume additive effect when it comes to estimate the bioaccessibility of mixtures of independently-aged As and Pb (or Cd and Pb) in soils. PMID:27062001

  1. 210Pb and 210Po, manganese and iron cycling across the O2/H2S interface of a permanently anoxic fjord: Framvaren, Norway

    Swarzenski, Peter W.; McKee, Brent A.; Sorenson, Kai; Todd, James F.

    1999-01-01

    Vertical profiles of dissolved and particulate 201Po and 210Pb were measured across the redox transition zone at Station F1 in Framvaren Fjord, Norway. In this fjord, a sharp decrease in pH above the O2/H2S interface facilitates the aerobic dissolution of MnO2. In contrast, Fe(II) concentrations begin to increase only at the O2/H2S interface depth. Activity profiles reveal that dissolved 210Po and 210Pb are sequestered efficiently by particulates in surface waters. As polonium-210 and lead-210 activities descend down into the aerobic manganese reduction (AMR) zone, they are remobilized during the reductive dissolution of the carrier phase oxyhydroxides. Both 210Po and 210Pb are highly enriched at the O2/H2S interface where an active community of microbes, such as anoxygenic phototrophs (e.g., Chromatium, Chlorobium sp.), thrives. The coincident peaks in 210Po and 210Pb and microbial biomass suggest a strong biological influence on the behavior of these radionuclides. There is a strong covariance between the vertical distribution of Mn and Pb, indicating that their redox cycling is closely coupled and is likely microbially mediated.

  2. Problems with the dating of sediment core using excess 210Pb in a freshwater system impacted by large scale watershed changes

    Pb-210 dating of freshwater and coastal sediments have been extensively conducted over the past 40 years for historical pollution reconstruction studies, sediment focusing, sediment accumulation and mixing rate determination. In areas where there is large scale disturbance of sediments and the watershed, the vertical profiles of excess 210Pb (210Pbxs) could provide erroneous or less reliable information on sediment accumulation rates. We analyzed one sediment core from Hendrix Lake in southwestern Arkansas for excess 210Pb and 137Cs. There is no decrease in excess 210Pb activity with depth while the 137Cs profile indicates sharp peak corresponding to 1963 and the 137Cs penetration depth of 137Cs corresponds to 1952. The historical data on the accelerated mercury mining during 1931–1944 resulted in large-scale Hg input to this watershed. Using the peak Hg activity as a time marker, the obtained sediment accumulation rates agree well with the 137Cs-based rates. Four independent evidences (two-marker events based on 137Cs and two marker events based on Hg mining activity) result in about the same sedimentation rates and thus, we endorse earlier suggestion that 210Pb profile always needs to be validated with at least one another independent method. We also present a concise discussion on what important factors that can affect the vertical profiles of 210Pbxs in relatively smaller lakes

  3. Time series study of a 17-year record of (7)Be and (210)Pb fluxes in northern Taiwan using ensemble empirical mode decomposition.

    Lee, H-I; Huh, C-A; Lee, T; Huang, N E

    2015-09-01

    Using the ensemble empirical mode decomposition (EEMD) and a significance test method, we have analyzed time series data on the fluxes of (7)Be and (210)Pb collected over a span of 17 y in Northern Taiwan. Among nine intrinsic mode functions (IMFs) extracted from the method five (IMF4-8) are non-trivial for (210)Pb and have adequate S/N with significant power in localized windows around the periodicities of 0.5 y, 1 y, 2 y, 5 y, and 11 y, respectively. For (7)Be, IMF5 and IMF8 with periods around 1 y and 11 y, respectively, have adequate S/N. The semi-annual and annual cycles represented by IMF4 and IMF5, respectively, are dominated by East Asian monsoon. The sum of IMF6 and IMF7 reveals an inter-annual cycle where both (7)Be and (210)Pb fluxes are well-correlated with the East Asian winter monsoon index (EAWMI). The close tracking of the (210)Pb and (7)Be in IMF8 cases may reflect an 11 y cycle; implying that it is caused by common climatologic factors, likely related to solar cycle, rather than their distinct production modes. PMID:26005772

  4. 210Po and 210Pb variations in fish species from the Aegean Sea and the contribution of 210Po to the radiation dose

    In recent years, there has been increasing interest in the significance of natural radionuclides, particularly 210Po, in the marine environment. 210Po, a naturally occurring alpha emitter, accumulates in marine organisms and reflects differences in their diets. In the literature, there is no data for 210Po and 210Pb activity concentrations for fish species on the Turkish coast of Aegean Sea. Therefore, in this study, multiple fish species were collected from six stations seasonally on the Turkish coast of Aegean Sea and were analyzed for their 210Po and 210Pb content. The 210Po and 210Pb concentrations in the fish samples were found to vary from undetectable levels to 499 ± 44 Bq kg−1 dry weight (dw) and from 1.0 ± 0.3 Bq kg−1 to 35 ± 4.0 Bq kg−1 (dw), respectively. There were no significant differences in the activity concentrations of 210Po and 210Pb in fish samples between seasons (ANOVA, P > 0.05). The highest dose contribution of 210Po to humans was calculated to be 10,530 μSv year−1.

  5. Toxicokinetics of polycyclic aromatic hydrocarbons in Eisenia andrei (Oligochaeta) using spiked soil

    Jager, T.; Anton Sanchez, F.A.; Muijs, B.; Velde, E.G. van der; Posthuma, L.

    2000-04-01

    The accumulation of four polycyclic aromatic hydrocarbons ([PAHs]; phenanthrene, pyrene, fluoranthene, and benzo[a]pyrene) was tested in the earthworm Eisenia andrei in a spiked artificial soil medium. A typical peak in the body residues was observed for all PAHs around day 7, which could not be explained from changes in the total soil concentration. It is argued that the most likely cause of this peak is a decrease in the concentration in pore water, the main bioavailable phase for earthworms. The decrease is caused by biodegradation while the low rate of mass transfer from the solid state precludes replenishment. To describe the data, bioavailability was assumed to decline exponentially in time, but the shape of the accumulation curves suggests a more abrupt change. Estimates of the uptake rate (k{sub 1}) are similar for all PAHs when expressed on soil solution basis (approximately 2,000 L/kg/d); the elimination rate (k{sub 2}) shows a decrease with K{sub ow} as expected, but the values tend to be slightly lower than literature data. The dynamic bioconcentration factors (k{sub 1}/k{sub 1}) agree well with an equilibrium partitioning between soil water and the phases inside the organism.

  6. Evaluation of the activity concentration of 226Ra, 228Ra and 210Pb in sediments from Antarctica in the Admiralty bay region

    The natural radionuclides from radioactive series of 238U, 235U and 232Th have been applied as tracers in environmental studies for understanding the dynamics that occur in both marine and terrestrial environment, as for example, in research of oceanic processes and management of the coastal region. In the marine environment, these radionuclides can be used to estimate biogeochemical fluxes of marine particles and nutrients that occur in the water column as well as in the sediment. Several research works applied the distribution and the respective disequilibrium degree of natural radionuclides in the environment, including geochronological models for obtaining historical information on samples of certain sediment profile. In this study we performed a radiochemical characterization of the distribution of 226Ra, 228Ra and 210Pb from a sedimentary column called 1B (248 cm long) collected in the Admiralty Bay, Antarctic Peninsula region. The methodology used included the acid leaching of sediment samples followed by the radiochemical sequential separation of 226Ra and 228Ra by co-precipitation with Ba(Ra)SO4 and 210Pb by co-precipitation with PbCrO4. All measurements were carried out by counting of gross alpha and gross beta measures in a low background gas flow proportional detector. The activity concentrations of 226Ra and 210Pb were used to estimate the unsupported 210Pb activities present in sediment profile 1 B. Based on unsupported 210Pb data and the application of the CIC model (Constant Initial Concentration), it was possible to determine the sedimentation rate of 0.59 ± 0.05 cm /year. (author)

  7. In vivo measurements of 210Pb in skull and knee geometries as an indicator of cumulative 222Rn exposure in underground coal mine in Brazil

    Full text: Cumulative exposure to radon can be evaluated by measuring 210Pb in bone, especially for underground uranium miners and for persons who live in areas where the concentration of radon is high. Lead, with its metabolism and distribution within the human body like its congenor calcium, will be accumulated in the skeleton. The bones of the skull and knee are two convenient locations for measuring 210Pb in vivo because these regions of the body present a high concentration of bone, the detectors are easily positioned and the likelihood of cross contribution from other organs or tissue is low. A radiological survey in non-uranium mines in Brazil indicated that an underground coal mine in Parana, the south of Brazil, had high radon concentration. In vivo measurements of 32 underground coal miners were performed in the IRD-CNEN whole body counter shielded room using an array of four high resolution germanium detectors. These detectors were positioned at the head or knee and were calibrated using anthropometric phantoms of the head and knee for converting the count rate due to 210Pb at 46.5 keV to units of activity (Bq). The activity of 210Pb in the head and knee were used to determine activity in the total skeleton as a means of estimating cumulative exposure to 222Rn. In vivo measurements of 210Pb in 8 of the 32 underground coal miners ranged between 50 Bq and 164 Bq suggesting that these workers received significant occupational exposure to 222Rn. (author)

  8. Carbon and nitrogen cycling in the Zhubi coral reef lagoon of the South China Sea as revealed by 210Po and 210Pb

    Highlights: → 210Po/210Pb disequilibria were used to trace export of POC and PON in a coral lagoon. → Recycling of POC and PON were quantified by a mass balance budget in a coral lagoon. → 210Po excess could be used to qualify the degradation of particulate organic matter. → Degradation rate constant of POM was much more in the lagoon than in the open sea. - Abstract: The radionuclides 210Po and 210Pb were examined to trace the cycling of particulate organic carbon (POC) and particulate organic nitrogen (PON) in the Zhubi coral reef lagoon. The net export flux of POC to the open sea is 14 mgC m-2 d-1. However, the net exchange of PON has not yet been observed. On average, the vertical export fluxes in the lagoon of POC and PON, as derived from 210Po/210Pb disequilibria, are 43 mgC m-2 d-1 and 13.8 mgN m-2 d-1, respectively. The deficit of 210Po relative to 210Pb in particulate matter provides evidence for the degradation of particulate organic matter. According to the mass balance budgets, 310 mgC m-2 d-1 and 121 mgN m-2 d-1 were recycled into dissolved fractions. Based on a first-order kinetics model, the degradation rate constants of POC and PON are 0.28 and 0.30 m-1, respectively. Thus, 210Po and 210Pb can quantify the cycling of carbon and nitrogen in this coral lagoon.

  9. Extraction of Plutonium From Spiked INEEL Soil Samples Using the Ligand-Assisted Supercritical Fluid Extraction (LA-SFE) Technique

    In order to investigate the effectiveness of ligand-assisted supercritical fluid extraction for the removal of transuranic contaminations from soils an Idaho National Engineering and Environmental Laboratory (INEEL) silty-clay soil sample was obtained from near the Radioactive Waste Management Complex area and subjected to three different chemical preparations before being spiked with plutonium. The spiked INEEL soil samples were subjected to a sequential aqueous extraction procedure to determine radionuclide portioning in each sample. Results from those extractions demonstrate that plutonium consistently partitioned into the residual fraction across all three INEEL soil preparations whereas americium partitioned 73% into the iron/manganese fraction for soil preparation A, with the balance partitioning into the residual fraction. Plutonium and americium were extracted from the INEEL soil samples using a ligand-assisted supercritical fluid extraction technique. Initial supercritical fluid extraction runs produced plutonium extraction technique. Initial supercritical fluid extraction runs produced plutonium extraction efficiencies ranging from 14% to 19%. After a second round wherein the initial extraction parameters were changed, the plutonium extraction efficiencies increased to 60% and as high as 80% with the americium level in the post-extracted soil samples dropping near to the detection limits. The third round of experiments are currently underway. These results demonstrate that the ligand-assisted supercritical fluid extraction technique can effectively extract plutonium from the spiked INEEL soil preparations

  10. 210Pb-226Ra chronology reveals rapid growth rate of Madrepora oculata and Lophelia pertusa on world's largest cold-water coral reef

    N. Tisnérat-Laborde

    2011-12-01

    Full Text Available Here we show the use of the 210Pb-226Ra excess method to determine the growth rate of corals from one of the world's largest known cold-water coral reef, the Røst Reef off Norway. Two large branching framework-forming cold-water coral specimens, one Lophelia pertusa and one Madrepora oculata were collected alive at 350 m water depth from the Røst Reef at ~67° N and ~9° E. Pb and Ra isotopes were measured along the major growth axis of both specimens using low level alpha and gamma spectrometry and the corals trace element compositions were studied using ICP-QMS. Due to the different chemical behaviors of Pb and Ra in the marine environment, 210Pb and 226Ra were not incorporated the same way into the aragonite skeleton of those two cold-water corals. Thus to assess of the growth rates of both specimens we have here taken in consideration the exponential decrease of initially incorporated 210Pb as well as the ingrowth of 210Pb from the decay of 226Ra. Moreover a~post-depositional 210Pb incorporation is found in relation to the Mn-Fe coatings that could not be entirely removed from the oldest parts of the skeletons. The 226Ra activities in both corals were fairly constant, then assuming constant uptake of 210Pb through time the 210Pb-226Ra chronology can be applied to calculate linear growth rate. The 45.5 cm long branch of M. oculata reveals an age of 31 yr and a~linear growth rate of 14.4 ± 1.1 mm yr−1, i.e. 2.6 polyps per year. However, a correction regarding a remaining post-depositional Mn-Fe oxide coating is needed for the base of the specimen. The corrected age tend to confirm the radiocarbon derived basal age of 40 yr (using 14C bomb peak with a mean growth rate of 2 polyps yr−1. This rate is similar to the one obtained in Aquaria experiments under optimal growth conditions. For the 80 cm-long specimen of L. pertusa a remaining contamination of metal-oxides is observed for the middle and basal part of the coral skeleton, inhibiting

  11. Removal of oxyfluorfen from spiked soils using electrokinetic soil flushing with the surrounding arrangements of electrodes.

    Risco, C; Rubí-Juárez, H; Rodrigo, S; López-Vizcaíno, R; Saez, C; Cañizares, P; Barrera-Díaz, C; Navarro, V; Rodrigo, M A

    2016-07-15

    This work reports the results of a study in which the remediation of soil that undergoes an accidental discharge of oxyfluorfen is carried out by using electrokinetic soil flushing (EKSF). Two different electrode configurations were tested, consisting of several electrodes surrounding an electrode of different polarity (so-called 1A6C, one anode surrounded by six cathodes, and 1C6A, one cathode surrounded by six cathodes). A pilot plant scale was used (with a soil volume of 175dm(3)) to perform the studies. During the tests, different parameters were measured daily (flowrates, pH, electrical conductivity and herbicide concentration in different sampling positions). Furthermore, at the end of the test, a complete post-mortem analysis was carried out to obtain a 3-D map of the pollution, pH and electrical conductivity in the soil. The results demonstrate that electrode arrangement is a key factor for effective pollutant removal. In fact, the 1A6C configuration improves the removal rate by 41.3% versus the 27.0% obtained by the 1C6A configuration after a period of 35days. Finally, a bench mark comparison of this study of soil remediation polluted with 2,4-D allows for significant conclusions about the scale-up and full-scale application of this technology. PMID:27058128

  12. Enhancement of plant growth and decontamination of nickel-spiked soil using PGPR.

    Tank, Neelam; Saraf, Meenu

    2009-04-01

    Phytoremediation i.e. the use of plants to adsorb, accumulate or detoxify contaminants is an emerging area of interest. A viable technology needs optimum biomass production in metal contaminated soil. Five strains of microbes were selected after testing their potential as plant growth promoters, on the basis of their phosphate solubilization ability, IAA, siderophore and HCN production and biocontrol potentials. They were examined for growth in synthetic medium supplemented with nickel and their MIC (2 mM) was determined. These isolates were also able to grow and produce siderophores in presence of heavy metals like Ni, Zn and Cd. A positive response of bacterial inoculants was observed in chickpea plants towards toxic effect of nickel present in soil at different concentration (0, 1 and 2 mM). Bacterial inoculants enhanced fresh and dry weight of plants even at 2 mM nickel concentration. Pot experiments indicated that presence of nickel at upto 1 mM enhanced plant growth compared to uninoculated nickel free plants. The accumulation of nickel/plant was just 50% in Pseudomonas inoculated plants as compared to uninoculated plants with 2 mM nickel concentration along with increased biomass. The results suggest the use of these PGPR to enhance plant growth in nickel-spiked land and remediate nickel from contaminated sites. PMID:18798171

  13. Lead Bioaccumulation Factor of Cockle Shell (Anadara granosa) Base on Biokinetic Study that Used Radiotracer 210Pb

    Lead is kind of hazardous heavy metal to human health and the concentration in the coastal environment should be monitored continuously because lead could be accumulated by marine biota. One of the monitoring techniques is bio indicator. Anadara granosa is a marine biota which spread in almost all Indonesian coastal, life in the bottom and mud sandy environment in the depth of until 4 meter and relatively still. Base on the book of environmental equilibrium balance DKI Jakarta, Anadara granosa is a macrozobenthos in Jakarta bay which have second highest density after Donax or with density of 14 individual per meter square. Base on the environmental equilibrium balance from 26 locations, 22 locations can be found Anadara granosa so this mollusk could be used for bio indicator. The objective of research for bioaccumulation that use 210Pb as a tracer is to find bio indicator base on biokinetic process which include concentration factor, uptake and depuration processes and biology half life. The result shows that Anadara granosa could be use as a lead bio indicator in Jakarta bay. (author)

  14. {sup 226}Ra, {sup 228}Ra and {sup 210}Pb determination in surface water and groundwater by liquid scintillation counting

    Faria, Ligia S.; Moreira, Rubens M., E-mail: ligsfaria@gmail.com, E-mail: rubens@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    The municipalities of Brumadinho and Nova Lima are located in the metropolitan region of Belo Horizonte city, in the State of Minas Gerais. These two sites are important due to being located inside an Environmental Protection Area inserted in the Iron Quadrangle. In addition to the mineral wealth, the region has geological features that include quartz conglomerates associated with uranium and a significant groundwater potential exhibiting quite peculiar and complex hydrogeological features, such as the quartzite aquifer itself. Nuclear techniques applied to hydrology, such as Liquid Scintillation Counting technique (LSC), make possible the evaluation of natural radioactivity in surface water and groundwater. The objectives of this study were the determination of the activities of the long half-life radionuclides of the uranium and thorium series, such as {sup 226}Ra, {sup 228}Ra and {sup 210}Pb, and provide an effective methodology to define if the direct consumption of these waters can cause risk to health due to its radioactivity. The results were compared with the recommendations of the Ministry of Health. (author)

  15. Isotopic constraints (210Pb, 228Th) on the sedimentary dynamics of contaminated sediments from a subtropical coastal lagoon (NW Mexico)

    Ruiz-Fernandez, A.; Hillaire-Marcel, C.; Ghaleb, B.; Paez-Osuna, F.; Soto-Jimenez, M.

    2001-11-01

    Six sediment push-cores were collected at a coastal lagoon system affected by urban and agriculture wastes. The sediments were analyzed for 228Th, 230Th, 232Th, 210Pb, 226Ra, and 137Cs. 137Cs activities were at background level for all samples. The 210Pbtot activities found in the area varied from 0.5 to 4.5 dpm g-1 with 210Pbsup levels ranging between 1.2-1.8 dpm g-1. Cores CHI and EPC showed flat profiles depleted of 210Pbxs, indicating the absence of recent sedimentation. Core CAI shows a flat 210Pbxs profile that seems to be bioturbated. Cores ERC and BRI show chaotic profiles with layers totally depleted in 210Pbxs, likely caused by resuspension triggered by storm conditions. High 228Th/232Th values observed at core ERC suggest that the resuspension event occurred less than 10 years ago. The contaminated sediment of the lagoon are frequently resuspended, re-oxygenated, and therefore the contaminating trace metals will continue to be easily remobilized in the food chain.

  16. 226Ra, 228Ra and 210Pb determination in surface water and groundwater by liquid scintillation counting

    The municipalities of Brumadinho and Nova Lima are located in the metropolitan region of Belo Horizonte city, in the State of Minas Gerais. These two sites are important due to being located inside an Environmental Protection Area inserted in the Iron Quadrangle. In addition to the mineral wealth, the region has geological features that include quartz conglomerates associated with uranium and a significant groundwater potential exhibiting quite peculiar and complex hydrogeological features, such as the quartzite aquifer itself. Nuclear techniques applied to hydrology, such as Liquid Scintillation Counting technique (LSC), make possible the evaluation of natural radioactivity in surface water and groundwater. The objectives of this study were the determination of the activities of the long half-life radionuclides of the uranium and thorium series, such as 226Ra, 228Ra and 210Pb, and provide an effective methodology to define if the direct consumption of these waters can cause risk to health due to its radioactivity. The results were compared with the recommendations of the Ministry of Health. (author)

  17. Evaluation of recent sedimentation rates in Guajara Bay (N Brazilian coast) with 210Pb and 137Cs

    In the last 50 years the Amazon region suffered the negative effects of urban growth and industrial and agricultural development. Belem, capital city of the state of Para located, is one of its greatest urban centers, and, within its influence, Guajara Bay receives wastes discharges from Belem, which introduce many organic and inorganic contaminants to this bay. As the environmental accumulation of these pollutants is deeply related to intensity and volume of sediments deposition, this study aims to evaluate recent sedimentation rates (in a time range of 60 years) in Guajara Bay. By using high resolution gamma spectrometry, a nuclear technique proper for the analysis of radionuclides 137Cs and 210Pb, recent sedimentation rates were assessed in three sediment cores collected in 2011. The mean sedimentation rates found were 0.85 ± 0.12 cm yr-1for Anadim core, 1.02 ± 0.17 cm yr-1for Outeiro core and 0.53 ± 0.04 cm yr-1for Tucunduba core, which are within the range of expected values for systems such as bays, estuaries and lagoons with anthropic presence (the case of Guajara Bay). (author)

  18. Trace element records in wetlands from Pantanal, Mato Grosso do Sul, Brazil dated by {sup 210}Pb

    Damatto, S.R.; Favaro, D.I.T.; Sakamoto, A.Y.; Mazzilli, B.P.; Valles, V. [Instituto de Pesquisas Energeticas e Nucleares IPEN, Centro de Metrologia das Radiacoes -Divisao de Radiometria Ambiental/CMRA, Butanta, SP (Brazil)

    2004-07-01

    The Pantanal in southwest Brazil is one of world largest freshwater wetlands. This natural ecosystem has been affected due to urban contamination, irregular use of the land, tourism without control, excessive agricultural defensive utilization, etc. In order to verify possible changes in this environment, a study was established in Pantanal da Nhecol dia, Mato Grosso do Sul, Brazil. Two sediment cores were collected in 2001 and the elements As, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Hf, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb, Zn and Zr were determined by neutron activation analysis technique - NAA. The radioactive {sup 210}Pb was used to determine sedimentation rates and the sediment age. The element concentrations ranged from mg kg{sup -1} to %. The majority of the elements and rare earths analyzed showed concentrations lower when compared with shale and earth crust values. Factorial analysis, mode R, was applied to the data. Only the elements Br, Hf and Zr showed concentrations slightly higher, probably due to variations on water level in flooding periods. A mean sedimentation rate of 0.61cmy{sup -1} was found for one core, which is in agreement with data from literature for this kind of ecosystem. (author)

  19. Vertical distribution of Th-isotope ratios, 210Pb, 226Ra and 137Cs in sediment cores from an estuary affected by anthropogenic releases

    In an estuary system highly polluted by mining and industrial activities, the sections of sediment cores affected by anthropogenic inputs of U-series radionuclides (due to fertilizer plants releases) were determined through the vertical profiles of Th-isotopic ratio (230Th/232Th). Also, when possible, a modified version of the 210Pb dating method was applied in the uncontaminated sections of these cores. Using the information provided by the Th-isotopic ratio and 210Pb methods, we were able to establish confident chronologies, covering the last century, in several of the analysed sediment cores. These chronologies will be used in forthcoming research to study the time evolution of pollutant concentrations in the estuary. Additionally, and based on the established chronologies, we have found that sedimentation rates have drastically increased in some zones of the estuary since the commencement of several industrial activities in the surrounding environment and since the construction of two dikes in the area

  20. Enrichment of {sup 210}Po and {sup 210}Pb in ash samples from oil shale-fired power plants in Estonia

    Ozden, B. [University of Tartu, Institute of Physics/Ege University, Institute of Nuclear Sciences (Estonia); Vaasma, T.; Kiisk, M.; Suursoo, S.; Tkaczyk, A.H. [University of Tartu,Institute of Physics (Estonia)

    2014-07-01

    Energy production in Estonia is largely dependent on the oil shale industry. Oil shale is a fossil fuel typically characterized by relatively high mineral composition, modest organic fraction (varying between 10 and 65%), high ash content (usually 45% to 50%), and average lower heating value of 8.4 MJ/kg{sup -1}. Oil shale-fired power plants account for 85% of Estonian electricity production and produce up to 6 million tons of oil shale ash annually. This ash contains elevated amounts of natural radionuclides (from the {sup 238}U and {sup 232}Th series and {sup 40}K), which were bound to oil shale during its formation. These radionuclides become enriched in ash fractions during the combustion process and are partially emitted to the atmosphere via fly ash and flue gases. Oil shale-fired electricity production is foreseen to remain a dominant trend in Estonia, suggesting that the radionuclide emissions to the atmosphere will continue in the future. The natural radionuclides {sup 210}Po and {sup 210}Pb, with half-lives of 138 days and 22.3 years respectively, originate from the radioactive decay of radionuclides of {sup 238}U series present in the earth's crust. These radionuclides are also built up artificially in the environment due to waste discharge from phosphate, oil, and gas industries, combustion of fossil fuels and other energy production as technically enhanced natural radionuclides. There are few studies on oil shale power plants influence on the levels of natural radioactivity in the surrounding areas. Realo, et al. reported that the annual doses from fly ash depositions over a 30 year period are in the range 90 - 200 μSv a{sup -1}. A study previously initiated by the University of Tartu, Institute of Physics (IPh) evaluated enrichment in the activity concentrations of {sup 238}U, {sup 226}Ra, {sup 210}Pb, {sup 232}Th, {sup 228}Ra and {sup 40}K in ash samples collected from Eesti Power Plant's circulating fluidized bed (CFB) boiler. According

  1. Recent atmospheric lead deposition recorded in an ombrotrophic peat bog of Great Hinggan Mountains, Northeast China, from 210Pb and 137Cs dating

    Radioactive markers are useful in dating lead deposition patterns from industrialization in peat archive. Peat cores were collected in an ombrotrophic peat bog in the Great Hinggan Mountains in Northeast China in September 2008 and dated using 210Pb and 137Cs radiometric techniques. The mosses in both cores were examined systematically for dry bulk density, water and ash content. Lead also was measured using atomic emission spectroscopy with inductively coupled plasma (ICP-AES). Both patterned peat profiles were preserved well without evident anthropogenic disturbance. Unsupported 210Pb and 137Cs decreased with the depth in both of the two sample cores. The 210Pb chronologies were established using the constant rate of supply model (CRS) and are in good agreement with the 137Cs time marker. Recent atmospheric 210Pb flux in Great Hinggan Mountains peat bog was estimated to be 337 Bq m-2 y-1, which is consistent with published data for the region. Lead deposition rate in this region was also derived from these two peat cores and ranged from 24.6 to 55.8 mg m-2 y-1 with a range of Pb concentration of 14-262 μg g-1. The Pb deposition patterns were consistent with increasing industrialization over the last 135-170 y, with a peak of production and coal burning in the last 50 y in Northeast China. This work presents a first estimation of atmospheric Pb deposition rate in peatlands in China and suggests an increasing trend of environmental pollution due to anthropogenic contaminants in the atmosphere. More attention should be paid to current local pollution problems, and society should take actions to seek a balance between economic development and environmental protection.

  2. Observation of atmospheric 210Pb and 212Pb originating from the 2004 eruptive activity of Asama volcano, Japan, and relevant 222Rn releasing from the erupting magma

    This paper describes a study of observation of atmospheric 210Pb and 212Pb possibly from the volcano (36 deg N, 138 deg E) activity in the title and of measurement of 222Rn releasing efficiency with the ash-fall deposit collected around the period. The aerosol sample was collected from Sep. 1, an eruption day, on a building terrace (10 m high) of Meiji University at Kawasaki, located at 140 km SE of the volcano, every 24 hr on the glass fiber filter using a high volume air sampler. The filter was cut out to 4 disks, which were packed into acrylic canisters with a window of a thin Mylar film for non-destructive γ-ray measurement. 210Pb and 212Pb radioactivities were determined by the 46.5- and 238.6-keV γ-rays with an LEPS (low energy photon spectrometer) and an HPGe spectrometer, respectively. The ash-fall sample from the eruption Sep. 14, was collected at Kanrakumachi, Gunma Pref., 40 km SE of the volcano, and measurement for the growth curve of 222Rn from the fall started 1 week after the eruption. A well-type HPGe spectrometer was used for determination of the 351.9-keV γ-ray of 222Rn from 214Pb in equilibrium, which was normalized by the 911.1-keV 228Ac γ-ray. 210Pb and 212Pb emitted into the atmosphere were suggested to have been transported 140 km within the time of a few times of the 212Pb half life (10.6 hr) on the northerly wind. 210Pb and 212Pb, and 222Rn were suggested to be a possibly useful tool of monitoring magmatic activities. (S.I.)

  3. Recent atmospheric lead deposition recorded in an ombrotrophic peat bog of Great Hinggan Mountains, Northeast China, from {sup 210}Pb and {sup 137}Cs dating

    Bao, K.; Xia, W.; Lu, X.; Wang, G. [Chinese Academy of Sciences, Changchun (China). Key Laboratory of Wetland Ecology & Environment

    2010-09-15

    Radioactive markers are useful in dating lead deposition patterns from industrialization in peat archive. Peat cores were collected in an ombrotrophic peat bog in the Great Hinggan Mountains in Northeast China in September 2008 and dated using {sup 210}Pb and {sup 137}Cs radiometric techniques. The mosses in both cores were examined systematically for dry bulk density, water and ash content. Lead also was measured using atomic emission spectroscopy with inductively coupled plasma (ICP-AES). Both patterned peat profiles were preserved well without evident anthropogenic disturbance. Unsupported {sup 210}Pb and {sup 137}Cs decreased with the depth in both of the two sample cores. The {sup 210}Pb chronologies were established using the constant rate of supply model (CRS) and are in good agreement with the {sup 137}Cs time marker. Recent atmospheric {sup 210}Pb flux in Great Hinggan Mountains peat bog was estimated to be 337 Bq m{sup -2} y{sup -1}, which is consistent with published data for the region. Lead deposition rate in this region was also derived from these two peat cores and ranged from 24.6 to 55.8 mg m{sup -2} y{sup -1} with a range of Pb concentration of 14-262 {mu} g g{sup -1}. The Pb deposition patterns were consistent with increasing industrialization over the last 135-170 y, with a peak of production and coal burning in the last 50 y in Northeast China. This work presents a first estimation of atmospheric Pb deposition rate in peatlands in China and suggests an increasing trend of environmental pollution due to anthropogenic contaminants in the atmosphere. More attention should be paid to current local pollution problems, and society should take actions to seek a balance between economic development and environmental protection.

  4. Distributions, inventories and isotopic composition of lead in 210Pb-dated peat cores from contrasting biogeochemical environments: Implications for lead mobility

    The use of concentration profiles of lead and other contaminant metals in 210Pb-dated ombrotrophic peat cores for reconstruction of historical trends in atmospheric deposition has become relatively well established. However, uncertainty remains over the validity of the assumption of post-depositional immobility of lead in peats. In particular, a number of studies have suggested that in saturated peat systems, lead is subject to diagenetic remobilisation and redistribution, with the result that 210Pb and lead profiles do not provide a historical record of deposition. Results are presented here for lead concentrations, inventories and stable isotope ratios and for 210Pb activities in two peat cores from locations close to the Glasgow industrial area in west-central Scotland. Contrasting biogeochemical conditions prevailed at the two sampling sites, with one being unsaturated and ombrotrophic while the other was saturated and minerotrophic. The results for the ombrotrophic peat core were compatible with information from other peat and lake sediment core studies, data for archived herbage samples and with known historical trends both in industrial activity and in the use of lead as an additive to petrol, giving a high degree of confidence in the 210Pb chronology and implied record of deposition. This provides strong support for the suggestion that lead is immobile in such systems. In contrast, the lead concentration profile and stable isotope data for the minerotrophic peat provided apparent temporal variations that were inconsistent with other studies and known historical trends, confirming that the saturated peat core did not provide a record of atmospheric deposition. This observation is consistent with the suggestion that lead is subject to diagenetic remobilisation and redistribution in saturated peats. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  5. Application of 210Pb geochronology by the reconstruction of historical radionuclides concentrations ( 137Cs et 239+240Pu ) in the columns of the Alboran Sea

    Full text: The marine sediments are considered as a final reservoir of radioactive contaminants. The 210Pb from atmospheric fallouts deposits is stored in sediments with those from 226Ra original lithogenic. The activity of 210Pb excess in the accumulated sediment is an important tool to study the chronological process of sedimentation on recent time scales at over 100 years. However, this method should be validated using at least one independent tracer which provides an unequivocal temporal marker as 137Cs from nuclear testing. This work presents a method to rebuild historic concentrations of 137Cs and 230+240Pu in the water column Alboran Sea and their corresponding stream sediment. This is achieved by coupling the radiometric dating of the sediment column profiles using three independent levels: the excess 210Pb, 137Cs and 239 +240Pu. On the other hand, a simple model of the water column has been adapted to this end by making use of atmospheric flow, the measured values of distribution coefficient (Kd) and a first approximation of the rate of sedimentation. The timing model CM-CSR (diffusion coefficient of sedimentation rate constant) has been successfully applied to the three independent profiles, and was able to determine the parameters of diffusion and mass sedimentation rate. The results obtained give some ideas on the fate of atmospheric inputs to the marine environment and, particularly, that of the Chernobyl accident. The results of the models showed that direct and deferred contributions of Chernobyl accident are negligible in the Alboran Sea. The annual input of 210Pb to the sediment was estimated at 720±150 Bq.m-2. by year, while the rate of sedimentation is about 0092±0.003 g.cm-2 by year. On the other hand, the model could successfully reconstruct historic concentrations of 137Cs and 239+240Pu in the water column, and was able to reproduce the work of the same elements in the sediment column

  6. 210Pb and composition data of near-surface sediments and interstitial waters evidencing anthropogenic inputs in Amazon River mouth, Macapa, Brazil

    Activity profiles of excess 210Pb determined in three sediment cores from Amazon River mouth, Macapa city, Brazil, provided the evaluation of sedimentation rates, contributing to a better knowledge of the hydrological conditions in the site that is the capital of Amapa State and is drained by the waters of the huge Amazon River. Chemical data were also determined in the sediments, allowing identify signatures coupled to anthropogenic inputs held in the past in Amapa State. Significant direct relationships between LOI (loss on ignition) and organic matter were found for all sediments profiles. Silica was found to be inversely related to organic matter in the three profiles; its decrease accompanied an increase on the specific surface of the sediments. This relationship was confirmed by a great number of inverse significant correlations among silica and oxides Na2O, K2O, CaO, MgO, Al2O3, P2O5, Fe2O3 and MnO. It was possible to identify the role of organic matter on adsorption of several oxides in the core sediments profiles. Apparent sediment mass accumulation rates corresponding to values between 450 and 2510 mg cm-2 yr-1 were obtained, and are compatible with the results of others studies. The 210Pb activities in one sampling point suggested the occurrence of anthropogenic inputs related to the initial period of the mining activities conducted in Serra do Navio, Amapa State, for the commercialization of Mn ores. This was reinforced by the abrupt fluctuations in chemical data obtained for the sediments and composition of the interstitial waters occurring there. The Atlantic hurricane activity also appeared to affect the sedimentation rates in the area, as two different values were recorded in each profile. - Highlights: → New 210Pb and composition dataset at the Amazon River mouth. → Chemical and 210Pb data revealed anthropogenic inputs in the area. → Mining activities at Serra do Navio for the commercialization of Mn ores.

  7. Recent atmospheric lead deposition recorded in an ombrotrophic peat bog of Great Hinggan Mountains, Northeast China, from 210Pb and 137Cs dating.

    Bao, K; Xia, W; Lu, X; Wang, G

    2010-09-01

    Radioactive markers are useful in dating lead deposition patterns from industrialization in peat archive. Peat cores were collected in an ombrotrophic peat bog in the Great Hinggan Mountains in Northeast China in September 2008 and dated using (210)Pb and (137)Cs radiometric techniques. The mosses in both cores were examined systematically for dry bulk density, water and ash content. Lead also was measured using atomic emission spectroscopy with inductively coupled plasma (ICP-AES). Both patterned peat profiles were preserved well without evident anthropogenic disturbance. Unsupported (210)Pb and (137)Cs decreased with the depth in both of the two sample cores. The (210)Pb chronologies were established using the constant rate of supply model (CRS) and are in good agreement with the (137)Cs time marker. Recent atmospheric (210)Pb flux in Great Hinggan Mountains peat bog was estimated to be 337 Bq m(-2)y(-1), which is consistent with published data for the region. Lead deposition rate in this region was also derived from these two peat cores and ranged from 24.6 to 55.8 mg m(-2)y(-1) with a range of Pb concentration of 14-262 microg g(-1). The Pb deposition patterns were consistent with increasing industrialization over the last 135-170 y, with a peak of production and coal burning in the last 50 y in Northeast China. This work presents a first estimation of atmospheric Pb deposition rate in peatlands in China and suggests an increasing trend of environmental pollution due to anthropogenic contaminants in the atmosphere. More attention should be paid to current local pollution problems, and society should take actions to seek a balance between economic development and environmental protection. PMID:20621757

  8. Spatial and temporal variability of 210Po and 210Pb in mussels (Mytilus galloprovincialis) at the Turkish Coast of the Aegean Sea

    In this study, the activity concentrations of 210Po and 210Pb were determined in mussel samples (Mytilus galloprovincialis) collected from the Turkish coast of the Aegean Sea. The samples were collected seasonally for a period of two years (2004-2006) at six coastal stations (Canakkale, Dikili, Foça, Çe°me, Didim, Bodrum). Mussels were separated into several groups according to their size (1-4, 4-6, >6 cm). The results showed that 210Po concentrations in mussels varied between 53±4 and 1960±60 Bq kg-1 dw. The highest activity 210Po concentrations were determined in winter samples of mussels with a shell length of 4-6 cm from Didim. In general, it was observed that the 210Pb concentration levels in mussels were lower than 210Po concentrations. The 210Po/210Pb activity concentration ratios exceeded unity for all mussel samples and averaged 26.0. The inter-site difference seen in 210Po concentrations can be due to both the natural background levels of sites and industrial activities. (author)

  9. Daily ingestion of 232Th, 238U, 226Ra, 228Ra and 210Pb in vegetables by inhabitants of Rio de Janeiro City

    The concentrations of the naturally occurring radionuclides 232Th, 238U, 210Pb, 226Ra and 228Ra were determined in the vegetables (leafy vegetables, fruit, root, bean and rice) and derived products (sugar, coffee, manioc flour, wheat flour, corn flour and pasta) consumed most by the adult inhabitants of Rio de Janeiro City. A total of 88 samples from 26 different vegetables and derived products were analyzed. The highest contribution to radionuclide intake arises from bean, wheat flour, manioc flour, carrot, rice, tomato and potato consumption. The estimated daily intakes due to the consumption of vegetables and derived products are 1.9 mBq of 232Th (0.47 μg), 2.0 mBq of 238U (0.17 μg), 19 mBq of 226Ra, 26 mBq of 210Pb and 47 mBq of 228Ra. The estimated annual effective dose due to the ingestion of vegetables and their derived products with the long-lived natural radionuclides is 14.5 μSv. Taking into account literature data for water and milk from Rio de Janeiro the dose value increases to 29 μSv, with vegetables and derived products responsible for 50% of the dose and water for 48%. 210Pb (62%) and 228Ra (24%) were found to be the main sources for internal irradiation

  10. Anthropogenic emissions of 210Po, 210Pb and 226Ra in an estuarine environment

    An extensive study on the distribution of natural radionuclides in an estuarine ecosystem located in Southwestern Spain is presented. This environment is highly affected by the wastes released by a phosphoric acid industry which uses phosphate rocks raw material for fertilizer production. This rock has generally high concentrations of U and its daughters. The estuary is formed by two rivers. Odiel and Tinto, which have a common mouth into the Atlantic Ocean and a salt marsh (Odiel marsh) affected by the income of Odiel riverwaters. This river receives directly the liquid and part of the solid (gypsum) wastes released from the industries. Besides that, most of the phosphogypsum wastes are stored in uncovered piles at the right margin of the Tinto river. The study has concluded that the wastes from such industries are the cause of the enhanced concentrations found at the bed of both river channels as well as the enhancement found in surface soils in certain zones of the Odiel wet marshland. Indeed, the Northern marsh and the Mojarrera channel at the Odiel marsh seem to be the main sinks of the contaminant released by the phosphoric acid industry. (author). 13 refs., 3 figs., 4 tabs

  11. Determination of {sup 210}Pb e {sup 226}Ra in tobacco leaves cultivated in the states of Rio de Grande do Sul e Alagoas - Brazil; Determinacao de {sup 210}Pb e {sup 226}Ra em folhas de tabaco cultivadas nos estados do Rio de Grande do Sul e Alagoas - Brasil

    Brandao, Y.B. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Valentim, E.; Hazin, C.A. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Antonio Filho, J. [Universidade Catolica de Pernambuco (UNICAP), Recife, PE (Brazil); Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

    2005-07-01

    The literature has shown that tobacco use causes damage to the health of cigarette users, manifesting itself in diseases with high mortality. Among these diseases include respiratory failure, pulmonary emphysema and lung cancer, among others. On the other hand, smoking contributes significantly to increasing the dose of natural radiation received by man, due to the presence of uranium series radionuclides, such as {sup 226}Ra, {sup 210}Pb and {sup 210}Po, in relatively high concentrations in fresh tobacco leaves. The determination of these radionuclides in this matrix is of great interest, once they can be incorporated not only by the active smoker, but also by the passive smoker. The results of this study confirmed the significant presence of {sup 226}Ra and {sup 210}Pb in tobacco samples collected and analyzed. The average values of activity concentration found in samples from the State of Alagoas were of Bq.kg{sup -1} 0.8 to {sup 210}Pb and 183.5 Bq.kg{sup -1} to {sup 226}Ra. For samples coming from the State of Rio Grande do Sul, these values were 4,0 Bq.kg{sup -1} to {sup 210}Pb and 161.3 Bq.kg{sup -1} to {sup 226}Ra.

  12. Grain yield and arsenic uptake of upland rice inoculated with arbuscular mycorrhizal fungi in As-spiked soils.

    Wu, Fuyong; Hu, Junli; Wu, Shengchun; Wong, Ming Hung

    2015-06-01

    A pot trial was conducted to investigate the effects of three arbuscular mycorrhizal (AM) fungi species, including Glomus geosporum BGC HUN02C, G. versiforme BGC GD01B, and G. mosseae BGC GD01A, on grain yield and arsenic (As) uptake of upland rice (Zhonghan 221) in As-spiked soils. Moderate levels of AM colonization (24.1-63.1 %) were recorded in the roots of upland rice, and up to 70 mg kg(-1) As in soils did not seem to inhibit mycorrhizal colonization. Positive mycorrhizal growth effects in grain, husk, straw, and root of the upland rice, especially under high level (70 mg kg(-1)) of As in soils, were apparent. Although the effects varied among species of AM fungi, inoculation of AM fungi apparently enhanced grain yield of upland rice without increasing grain As concentrations in As-spiked soils, indicating that AM fungi could alleviate adverse effects on the upland rice caused by As in soils. The present results also show that mycorrhizal inoculation significantly (p husk, straw, and root in soils added with 70 mg kg(-1) As. The present results suggest that AM fungi are able to mitigate the adverse effects with enhancing rice production when growing in As-contaminated soils. PMID:23292227

  13. Study of the particulate matter transfer and dumping using 210 Po et le 210 Pb. Application to the Gulf of Biscary (NE Atlantic Ocean) and the Gulf of Lion (NW Mediterranean Sea) continental margins

    210 Po and 210 Pb activities and fluxes were measured on seawater, sediment-trapped material collected during one year and sediment. Focalization of 210 Pb is clearly noticed on the Cap-Ferret canyon (Gulf of Biscary) and the Lacaze-Duthiers canyon (western part of the Gulf of Lion). In both sites, 210 Pb fluxes in traps and sediment are always higher than 210 Pb flux available from atmospheric and in situ production. On the contrary, Grand-Rhone canyon and its adjacent open slope exhibit a 210 Pb budget near equilibrium in the near-bottom sediment traps, but focalization is important in the sediment. For the entire Gulf of Lion margin, focalization of 210 Pb in the sediment occurred principally between 500 and 1500 m water depth on the slope, and on the middle shelf mud-patch. 210 Po and 210 Pb have been used in the Cap Ferret and Grand-Rhone canyons to characterize the origin of the particulate trapped material. Two main sources feed the water column. The first source, localized in surface waters, is constituted by biogenic particles from primary production and lithogenic material. The second source, deeper, is due to resuspension at the shelf break and/or on the open slope. In each site, 210 Po and 210 Pb activities of the trapped particles did not show any relations with the major constituents. Quantity of particles appeared to be the main factor regulating adsorption processes of these nuclides. Sedimentation rates based on 210 Po profiles decreased with increasing water depth, from 0.4 ti 0.06 cm y-1 on the Cap Ferret canyon (400 to 3000 m water depth) and from 0.5 to 0.05 cm y-1 for the entire Gulf of Lion margin (50 to 2000 m water depth). (author)

  14. Fluxes of 238U Series Radionuclides in the Industrial Production of Dicalcium Phosphate and the Biokinetic Analysis of 210Pb and 210Po in Poultry Tissue Due to its Ingestion

    NORM derived from the wet acid digestion of phosphate rock might represent a serious problem facing the phosphate industry. The aim of this work is to discuss both: (a) the fluxes of the 238U series radionuclides (U and Th isotopes, 226Ra, 210Pb and 210Po) during the DCP production process and, (b) the accumulation of 210Pb and 210Po in chicken tissues due to the ingestion of DCP. Industrial samples were collected from different production steps at a factory in Spain that uses phosphate rock from Morocco. The results showed that whereas uranium is equally distributed within products and by-products, thorium and 210Po are mainly eliminated through the sludges and 210Pb is mostly found in the final product (DCP). The 210Pb and 210Po results in chicken tissues and faeces after animals were bred with different amounts of DCP for 42 days have shown that about 95% of the ingested 210Pb and 210Po was immediately excreted. From the amount accumulated in tissues it was observed that whereas 210Pb is mostly found in bones, 210Po accumulates in the liver and kidneys. A one compartment non-linear kinetic model has been developed in order to determine the variation of the total activity of 210Pb and 210Po accumulated in the chicken body throughout its 6 weeks life. This model correctly reproduces experimental results and also allows calculating of transfer rates for 210Pb and 210Po, useful for first order models, that is, under stationary metabolic conditions. (author)

  15. {sup 210}Pb dating of sediments from the central and northern Adriatic Sea: deposition and preservation of sedimentary organic carbon

    Hamilton, T. F., LLNL

    1998-04-01

    Lead-210 ({sup 21O}Pb) and organic C depth distribution profiles in sediments from the northern and central Adriatic Sea were measured as part of the EEC funded project on Eutrophic Limits of the Northern Adriatic (ELNA). {sup 210}Pb derived mass-accumulation rates decrease southward from between 0.15 and 0.2 g cm{sup -2}y{sup -1} close to the Po River outflow (> 24 m, water depth) to less than 0.04 g cm{sup -2}y{sup -1} in the Jabuka Pit (246 m, water depth) in the central Adriatic Sea. The mass- accumulation rates obtained in the Jabuka Pit correspond to mean sedimentation rates of about 0.03 cm y{sup -1} (ref. porosity = 0.5) and fall between 5 to 20 times lower than rates found for north Adriatic shelf cores. Estimated sedimentation rates are considered as upper limits because of the possible effects of bioturbation and physical disturbance on the {sup 21O}Pb sedimentary record but are consistent with data from previous work. Rates of sediment accumulation and carbon burial appear to be strongly influenced by the transport of fluvial materials from land and transport of fine-grained particles. First-order estimates of organic C burial rates into surface sediment ranged from 1 to 0.028 mMol cm{sup -2}y{sup -1} between the Po delta and the Jabuka Pit regions, respectively. We estimate that a maximum of 50% of organic C preserved in surface sediment may be derived from biological production in the overlying water column.

  16. {sup 210}Pb geochronology and chemical characterization of sediment cores from lakes of the Parana river alluvial plain

    Teixeira, L.F.L.; Damatto, S.R.; Scapin, M.A. [IPEN - Instituto de Pesquisas Energeticas e Nucleares (Brazil); Remor, M.B.; Sampaio, S.C. [UNIOESTE - Universidade Estadual do Oeste do Parana (Brazil)

    2014-07-01

    The flood plain of the upper Parana River is located among the lakes formed by the Brazilian hydroelectric plants being the last part of the Parana river, in Brazil, where there is an ecosystem with interaction river-flood plain. This flood plain has considerable habitat variability, with great diversity of terrestrial and aquatic species, and the floods are the main factor that regulates the operation of this ecosystem. The seasonality of the flood pulses is mainly influenced by the El Nino phenomenon, which increases precipitation in the drainage basin of the flood plain of the upper Parana River. Because of its unique characteristics this ecosystem is the subject of intense study since 1980, mainly from the ecological point of view. Therefore, two sediment cores were collected in the ponds formed by the floods, Patos pond and Garcas pond, in order to characterize the sediment chemically and evaluate a possible historic contamination. The trace element concentrations As, Ba, Br, Ce, Co, Cr, Cs, Eu, Hf, La, Lu, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn (mg.kg{sup -1}) and the major elements Si, Al, Fe, Ti, K, Ca, Mg, P, V, Mn, and Na (%) were determined in the sediment cores dated by {sup 210}Pb method, using instrumental neutron activation analysis, X-ray fluorescence and gross beta counting, respectively. The results obtained for the elements Ce, Cr, Cs, La, Nd, Sc, Sm and Th are higher than the values of Upper Continental Crust for both ponds. The sedimentation rates obtained for Garca pond, 0.77 cm.y{sup -1}, and Patos pond, 0.62 cm.y{sup -1} are in agreement with studies performed in sedimentary environments similar to the present work, such as Brazilian wetland Pantanal. The enrichment factor and the geo-accumulation index were used to assess the presence of anthropogenic sources of pollution. Document available in abstract form only. (authors)

  17. 210Pb geochronology and chemical characterization of sediment cores from lakes of the Parana river alluvial plain

    The flood plain of the upper Parana River is located among the lakes formed by the Brazilian hydroelectric plants being the last part of the Parana river, in Brazil, where there is an ecosystem with interaction river-flood plain. This flood plain has considerable habitat variability, with great diversity of terrestrial and aquatic species, and the floods are the main factor that regulates the operation of this ecosystem. The seasonality of the flood pulses is mainly influenced by the El Nino phenomenon, which increases precipitation in the drainage basin of the flood plain of the upper Parana River. Because of its unique characteristics this ecosystem is the subject of intense study since 1980, mainly from the ecological point of view. Therefore, two sediment cores were collected in the ponds formed by the floods, Patos pond and Garcas pond, in order to characterize the sediment chemically and evaluate a possible historic contamination. The trace element concentrations As, Ba, Br, Ce, Co, Cr, Cs, Eu, Hf, La, Lu, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn (mg.kg-1) and the major elements Si, Al, Fe, Ti, K, Ca, Mg, P, V, Mn, and Na (%) were determined in the sediment cores dated by 210Pb method, using instrumental neutron activation analysis, X-ray fluorescence and gross beta counting, respectively. The results obtained for the elements Ce, Cr, Cs, La, Nd, Sc, Sm and Th are higher than the values of Upper Continental Crust for both ponds. The sedimentation rates obtained for Garca pond, 0.77 cm.y-1, and Patos pond, 0.62 cm.y-1 are in agreement with studies performed in sedimentary environments similar to the present work, such as Brazilian wetland Pantanal. The enrichment factor and the geo-accumulation index were used to assess the presence of anthropogenic sources of pollution. Document available in abstract form only. (authors)

  18. {sup 137}Cs and excess {sup 210}Pb deposition patterns in estuarine and marine sediment in the central region of the Great Barrier Reef Lagoon, north-eastern Australia

    Pfitzner, John E-mail: j.pfitzner@aims.gov.au; Brunskill, Gregg E-mail: g.brunskill@aims.gov.au; Zagorskis, Irena E-mail: i.zagorskis@aims.gov.au

    2004-07-01

    This paper focuses on the distribution of {sup 137}Cs and {sup 210}Pb{sub xs} in 51 estuarine and marine sediment cores collected between the Upstart Bay and Rockingham Bay in the Great Barrier Reef Lagoon, north-eastern Australia. Historical records of {sup 210}Pb{sub xs} and {sup 137}Cs atmospheric deposition and present day terrestrial inventories in north-eastern Australia are presented. {sup 210}Pb{sub xs} and {sup 137}Cs fluxes measured on suspended sediments in the Burdekin River are considered to be a source of recent inputs of these nuclides to the nearshore region of this part of the Great Barrier Reef. Direct correlations between sediment nuclide inventories, maximum detectable depths, and sediment mass accumulation rates (MARs), calculated using both {sup 137}Cs and {sup 210}Pb{sub xs}, are explored. In relation to inventories of {sup 210}Pb{sub xs}, 60% of atmospheric fallout {sup 137}Cs appears to be missing from the sediments. The reasons for these differences in two tracers, primarily of atmospheric origin, are discussed in terms of the geochemical properties of these two nuclides. Evidence is presented to support the hypothesis that the {sup 137}Cs distribution in these cores can be a useful independent tracer which provides confirmation of MARs calculated from the decay of {sup 210}Pb{sub xs}.

  19. Using natural radionuclides 210Po and 210Pb in GEOTRACES data from the North Atlantic to estimate particulate and biologically reactive trace element scavenging and regeneration

    Rigaud, Sylvain; Church, Thomas

    2016-04-01

    Central to understanding the coupling of oceanic carbon and nutrient cycles are trace elements that can limit ocean production and ultimately climate change. These include elements that are both lithogenic (particle reactive) and biogenic (biologically reactive) central to particle scavenging, exchange and bioavailability. The natural 210Po and 210Pb radionuclide (granddaughter/parent) pair provides the radiometric means to model particle scavenging and exchange in the ocean on monthly to annual time scales. Data on dissolved (0.2 μm, >53μm) 210Po (t1/2= 138.4 d) and 210Pb (T1/2 = 22.3 y) are available from seven complete water profiles during two U.S. GEOTRACES cruises that transited the North Atlantic during fall 2010 and 2011. The transects correspond to a wide range of marine environments: coastal slopes at the western and eutrophic up-welling at the eastern margins, Saharan dust sources from the east, hydro-thermal vents in the TAG plume on the Mid-Atlantic Ridge, and oligotrophic gyres in both the western and eastern basins. Steady state box modeling at each depth interval was employed to estimate radionuclide exchange rates at the fine-large particle and fine particulate-dissolved interface, in terms of biological uptake, and net of radioactive support or decay. By proxy, the results should predict the rates of biological (210Po) and particle reactive (210Pb) trace element adsorption and resorption, vertical particulate and carbon export, and respective residence times. The model results show the contrasting chemical behaviour of the two nuclides over the large range of oceanic conditions encountered in the North Atlantic. In the surface ocean, 210Po scavenging is linearly correlated with the concentration of particulate organic carbon (POC) in large particles, supporting the role of biogenic particles in 210Po bioaccumulation and export. At depth, 210Po exhibits significant widespread deficit with respect to 210Pb, which could in part be attributed to in

  20. Study of the particulate matter transfer and dumping using {sup 210} Po et le {sup 210} Pb. Application to the Gulf of Biscary (NE Atlantic Ocean) and the Gulf of Lion (NW Mediterranean Sea) continental margins; Etude du transfert et du depot du materiel particulaire par le {sup 210} Po et le {sup 210} Pb. Application aux marges continentales du Golfe de Gascogne (NE Atlantique) et du Golfe du Lion (NW Mediterranee)

    Radakovitch, O.

    1995-07-07

    {sup 210} Po and {sup 210} Pb activities and fluxes were measured on seawater, sediment-trapped material collected during one year and sediment. Focalization of {sup 210} Pb is clearly noticed on the Cap-Ferret canyon (Gulf of Biscary) and the Lacaze-Duthiers canyon (western part of the Gulf of Lion). In both sites, {sup 210} Pb fluxes in traps and sediment are always higher than {sup 210} Pb flux available from atmospheric and in situ production. On the contrary, Grand-Rhone canyon and its adjacent open slope exhibit a {sup 210} Pb budget near equilibrium in the near-bottom sediment traps, but focalization is important in the sediment. For the entire Gulf of Lion margin, focalization of {sup 210} Pb in the sediment occurred principally between 500 and 1500 m water depth on the slope, and on the middle shelf mud-patch. {sup 210} Po and {sup 210} Pb have been used in the Cap Ferret and Grand-Rhone canyons to characterize the origin of the particulate trapped material. Two main sources feed the water column. The first source, localized in surface waters, is constituted by biogenic particles from primary production and lithogenic material. The second source, deeper, is due to resuspension at the shelf break and/or on the open slope. In each site, {sup 210} Po and {sup 210} Pb activities of the trapped particles did not show any relations with the major constituents. Quantity of particles appeared to be the main factor regulating adsorption processes of these nuclides. Sedimentation rates based on {sup 210} Po profiles decreased with increasing water depth, from 0.4 ti 0.06 cm y-1 on the Cap Ferret canyon (400 to 3000 m water depth) and from 0.5 to 0.05 cm y-1 for the entire Gulf of Lion margin (50 to 2000 m water depth). (author). 243 refs.

  1. Removal of polycyclic aromatic hydrocarbons in soil spiked with model mixtures of petroleum hydrocarbons and heterocycles using biosurfactants from Rhodococcus ruber IEGM 231.

    Ivshina, Irina; Kostina, Ludmila; Krivoruchko, Anastasiya; Kuyukina, Maria; Peshkur, Tatyana; Anderson, Peter; Cunningham, Colin

    2016-07-15

    Removal of polycyclic aromatic hydrocarbons (PAHs) in soil using biosurfactants (BS) produced by Rhodococcus ruber IEGM 231 was studied in soil columns spiked with model mixtures of major petroleum constituents. A crystalline mixture of single PAHs (0.63g/kg), a crystalline mixture of PAHs (0.63g/kg) and polycyclic aromatic sulfur heterocycles (PASHs), and an artificially synthesized non-aqueous phase liquid (NAPL) containing PAHs (3.00g/kg) dissolved in alkanes C10-C19 were used for spiking. Percentage of PAH removal with BS varied from 16 to 69%. Washing activities of BS were 2.5 times greater than those of synthetic surfactant Tween 60 in NAPL-spiked soil and similar to Tween 60 in crystalline-spiked soil. At the same time, amounts of removed PAHs were equal and consisted of 0.3-0.5g/kg dry soil regardless the chemical pattern of a model mixture of petroleum hydrocarbons and heterocycles used for spiking. UV spectra for soil before and after BS treatment were obtained and their applicability for differentiated analysis of PAH and PASH concentration changes in remediated soil was shown. The ratios A254nm/A288nm revealed that BS increased biotreatability of PAH-contaminated soils. PMID:27015374

  2. Use of radionuclide techniques 137Cs, 210PbEX and Be) to assess soil erosion in Moroccan agriculture lands

    Water erosion is one of the major environmental and agricultural problems causing serious socio-economic impairment for not only develop countries but also developing countries. It reduces the fertility and productivity of agricultural lands and it is besides a major source of surface water pollution. On the other hand, intensive or improper farming accelerates greatly this phenomenon. (Author)

  3. Chemical composition of scales generated from oil industry and correlation to radionuclide contents and gamma-ray measurements of (210)Pb.

    Al Attar, Lina; Safia, Bassam; Abdul Ghani, Basem

    2016-03-01

    Scale generated from the maintenance of equipment contaminated by naturally occurring radioactive materials may contain also chemical components that cause hazardous pollution to human health and the environment. This study spotlights the characterisation of chemical pollutants in scales in relation to home-made comparison samples as no reference material for such waste exists. Analysis by energy dispersive x-ray fluorescence, with accuracy and precision better than 90%, revealed that barium was the most abundant element in scale samples, ranging from 1.4 to 38.2%. The concentrations of the toxic elements such as lead and chromium were as high as 2.5 and 1.2% respectively. Statistically, high correlation was observed between the concentration of Ba and Sr, sample density, radionuclide contents ((210)Pb and (226)Ra) and self-attenuation factor used for the radio-measurements. However, iron showed a reverse correlation. Interpretation of data with regards to the mineralogical components indicated that (226)Ra and (210)Pb co-precipitated with the insoluble salt Ba0.75Sr0.25SO4. Since both Ba and Sr have high Z, samples of high density (ρ) were accompanied with high values of self-attenuation correction factors (Cf) for the emitted radiation; correlation matrix of Pearson reached 0.935 between ρ and Cf. An attempt to eliminate the effect of the elemental composition and improve gamma measurements of (210)Pb activity concentration in scale samples was made, which showed no correction for self-attenuation was needed when sample densities were in the range 1.0-1.4 g cm(-3). For denser samples, a mathematical model was developed. Accurate determinations of radionuclide and chemical contents of scale would facilitate future Environmental Impact Assessment for the petroleum industry. PMID:26741561

  4. Temporal evolution of natural radionuclides distributions 238U, 234Th, 226Ra, 228Ra, 210Pb and 210Po in the Bransfield strait, Antarctica peninsula

    Research on the distribution of natural radionuclides in Antarctica is rare and thus, there is great interest in to know their occurrence and factors related to its mobilization, transference and accumulation in this extremely fragile environment. Natural radionuclides have been used intensively as tracers in the ocean, helping to better understand processes as sinking and particle resuspension, water masses mixture and oceanic circulation. 234Th (t½ = 24.1 days) is a particle-reactive radionuclide produced continuously in seawater by the decay of its soluble precursor conservative with salinity 238U (t½ = 4.5 109 years). Since 234Th presents relatively short half-life, it is used to quantify processes that occur in temporal scale varying from days to weeks. The disequilibrium 234Th/238U in the surface ocean has been applied to estimate carbon fluxes exported via sinking material. The flux of particles biologically productive out of the euphotic zone in the Southern Ocean has special attention due to its importance in the control of CO2 atmospheric concentrations. The radionuclides 210Pb (t½ = 22.3 years) and 210Po (t½ = 138 days) are also particle-reactive. The disequilibrium 210Po/210Pb has been used to estimate fluxes of particles exported in the ocean in the time scale of weeks. The long-lived Ra isotopes, 226Ra (t½ = 1,600 years) and 228Ra (t½ = 5.75 years) are soluble in seawater, presenting unique properties that make them excellent tracers of water masses. This research work had the aim to study the distributions of natural radionuclides 238U, 234Th, 22'6Ra, 22'8Ra, 210Pb and 210Po in the Bransfield Strait during 2 samplings carried out in the 2011 Austral Summer (OPERANTAR XXIX and XXX). (author)

  5. Determination of the sedimentation rates in the Sepetiba bay northeastern area by using dating with the excesses {sup 210} Pb radioisotope; Determinacao das taxas de sedimentacao na porcao nordeste da baia de Sepetiba utilizando datacao com o radioisotopo {sup 210} Pb em excesso

    Forte, Cristiane Maria Sampaio

    1996-07-01

    {sup 210} Pb dating, using two modes of data analysis, CIC and CRS, was used to determine sedimentation in the North East part of Sepetiba Bay. {sup 210} Pb was leached from samples using dilute HBr and subsequently separated onto anionic exchange columns, followed by re-extraction and precipitation as Pb CrO{sub 4}. The original method was modified by the introduction of a pre-digestion step whose purpose was to liberate the lead bound as sulphide. The sedimentation rates found o.68 - 0.98 cm.y{sup -1} were moderate, compared to other authors estimates. Dating using the CRS model showed a maximum rate of sedimentation in the period between 1954 and 1977, when the riverine input was probably at its greatest. The CRS model appears to be more applicable to the data, since it works over longer periods and allows for variations in sedimentation rate. (author)

  6. Verification of the correlation between the {sup 210} Pb and the chemical composition of the incrustations found on gas pipelines and the implication on radiological protection; Verificacao da correlacao entre a atividade de {sup 210}Pb e a composicao quimica de incrustacoes encontradas em linhas de gas e a implicacao em protecao radiologica

    Gomes, Franciane Martins de Carvalho

    2004-07-01

    In the last decades, the occurrence of solid residual deposits, known as black powder, in natural-gas pipelines, gathering systems and compression equipment from gas industries has raised increasing regulatory concerns in terms of radiological protection. Concerns are also raised about the waste disposal and management of the radioactive residues eventually produced. Recent projections indicate a significant increase in the production of natural-gas and its products, due to a growing commercial demand, which leads to the production of huge amounts of residues. Thus, more information is needed in order to allow a preliminary evaluation of the radiological profile of this type of industry. In black powder residues, the most prevalent radioisotope is {sup 210}Pb. The present work aimed to investigate the correlation between the chemical composition of the residue and the concentration of {sup 210}Pb, in black powder samples collected at Bacia de Campos, in the State of Rio de Janeiro, Brazil. The main objective was to generate information to regulatory authorities, to the National Commission of Nuclear Energy (CNEN) and to companies that produce natural-gas, such as PETROBRAS. Based on the information, the gas producing companies could elaborate radiological protection guidelines, and also decide about the need for implementation of a waste management program at the installation. The samples of black powder analyzed at the present work have confirmed the existence of such correlation between the concentration of {sup 210}Pb and chemical parameters. In principle, the present results make the use of such correlation feasible for preliminary evaluations of the {sup 210}Pb levels in natural-gas installations. On the other hand, given the geographic limitations, a broader study is recommended, in order to evaluate the investigated correlation, which could be used as a guiding tool for the Brazilian industry of production and processing of natural-gas.(author)

  7. Evaluation of uncertainty and detection limits in {sup 210}Pb and {sup 210}Po measurement in water by alpha spectrometry using {sup 210}Po spontaneous deposition onto a silver disk

    Fernandez, Pedro L., E-mail: pedroluis.fernandez@unican.es [Department of Medical and Surgical Sciences (Medical Physics Section), Faculty of Medicine, University of Cantabria, 39011 Santander (Cantabria) (Spain); Gomez, Jose; Rodenas, Carmen [Department of Medical and Surgical Sciences (Medical Physics Section), Faculty of Medicine, University of Cantabria, 39011 Santander (Cantabria) (Spain)

    2012-04-15

    An easy and accurate method for the determination of {sup 210}Pb and {sup 210}Po in water using {sup 210}Po spontaneous deposition onto a silver disk is proposed and assessed for its detection capabilities according to the ISO Guide for the expression of uncertainty in measurement (GUM) and ISO Standard 11929-7 concerning the evaluation of the characteristic limits for ionizing radiation measurements. The method makes no assumption on the initial values of the activity concentrations of {sup 210}Pb, {sup 210}Bi and {sup 210}Po in the sample to be analyzed, and is based on the alpha spectrometric measurement of {sup 210}Po in two different aliquots: the first one measured five weeks after the sampling date to ensure radioactive equilibrium between {sup 210}Pb and {sup 210}Bi and the second after a sufficient time for the ingrowth of {sup 210}Po from {sup 210}Pb to be significant. As shown, for a recommended time interval of seven months between {sup 210}Po measurements, the applicability of the proposed method is limited to water samples with a {sup 226}Ra to {sup 210}Pb activity ratio C{sub Ra}/C{sub Pb}{<=}4, as usual in natural waters. Using sample and background counting times of 24 h and 240 h, respectively, the detection limit of the activity concentration of each radionuclide at the sampling time for a 1 L sample typically varies between 0.7 and 16 mBq L{sup -1} for {sup 210}Pb in water samples with an initial activity of {sup 210}Po in the range 0-200 mBq L{sup -1}, and between 0.6 and 8.5 mBq L{sup -1} for {sup 210}Po in water samples with an initial activity of {sup 210}Pb in the same range. - Highlights: Black-Right-Pointing-Pointer {sup 210}Pb and {sup 210}Po measurement in water by {sup 210}Po spontaneous deposition onto silver disks. Black-Right-Pointing-Pointer {sup 210}Pb and {sup 210}Po determination based on {sup 210}Po measurement in two different aliquots. Black-Right-Pointing-Pointer Evaluation of characteristic limits in radioactivity

  8. 210Pb and 137Cs as chronometers for salt marsh accretion in the Venice Lagoon - links to flooding frequency and climate change

    Five salt marsh sediment cores from different parts of the Venice Lagoon were studied to determine their depositional history and its relationship with the environmental changes occurred during the past ∼100 years. X-radiographs of the cores show no disturbance related to particle mixing. Accretion rates were calculated using a constant flux model applied to excess 210Pb distributions in the cores. The record of 137Cs fluxes to the sites, determined from 137Cs profiles and the 210Pb chronologies, shows inputs from the global fallout of 137Cs in the late 1950s to early 1960s and the Chernobyl accident in 1986. Average accretion rates in the cores are comparable to the long-term average rate of mean sea level rise in the Venice Lagoon (∼0.25 cm y-1) except for a core collected in a marsh presumably affected by inputs from the Dese River. Short-term variations in accretion rate are correlated with the cumulative frequency of flooding, as determined by records of Acqua Alta, in four of the five cores, suggesting that variations in the phenomena causing flooding (such as wind patterns, storm frequency and NAO) are short-term driving forces for variations in marsh accretion rate

  9. Examining (239+240)Pu, (210)Pb and historical events to determine carbon, nitrogen and phosphorus burial in mangrove sediments of Moreton Bay, Australia.

    Sanders, Christian J; Santos, Isaac R; Maher, Damien T; Breithaupt, Joshua L; Smoak, Joseph M; Ketterer, Michael; Call, Mitchell; Sanders, Luciana; Eyre, Bradley D

    2016-01-01

    Two sediment cores were collected in a mangrove forest to construct geochronologies for the previous century using natural and anthropogenic radionuclide tracers. Both sediment cores were dated using (239+240)Pu global fallout signatures as well as (210)Pb, applying both the Constant Initial Concentration (CIC) and the Constant Rate of Supply (CRS) models. The (239+240)Pu and CIC model are interpreted as having comparable sediment accretion rates (SAR) below an apparent mixed region in the upper ∼5 to 10 cm. In contrast, the CRS dating method shows high sediment accretion rates in the uppermost intervals, which is substantially reduced over the lower intervals of the 100-year record. A local anthropogenic nutrient signal is reflected in the high total phosphorus (TP) concentration in younger sediments. The carbon/nitrogen molar ratios and δ(15)N values further support a local anthropogenic nutrient enrichment signal. The origin of these signals is likely the treated sewage discharge to Moreton Bay which began in the early 1970s. While the (239+240)Pu and CIC models can only produce rates averaged over the intervals of interest within the profile, the (210)Pb CRS model identifies elevated rates of sediment accretion, organic carbon (OC), nitrogen (N), and TP burial from 2000 to 2013. From 1920 to 2000, the three dating methods provide similar OC, N and TP burial rates, ∼150, 10 and 2 g m(-2) year(-1), respectively, which are comparable to global averages. PMID:26004816

  10. 210Pb chronology and trace metal geochemistry at Los Tuxtlas, Mexico, as evidenced by a sedimentary record from the Lago Verde crater lake

    Carolina Ruiz-Fernández, Ana; Hillaire-Marcel, Claude; Páez-Osuna, Federico; Ghaleb, Bassam; Caballero, Margarita

    2007-03-01

    Lago Verde is a fresh-water maar found on the lower slopes of San Martin volcano, at the Sierra de Los Tuxtlas, Mexico, currently the northernmost remnant of the tropical rain forest in America. 210Pb and 137Cs analyzed in a sediment core were used to reconstruct the historical fluxes of Ag, Cd, Cu, Pb, Hg and Zn to the site during the last ˜ 150 yr. The 210Pb xs-derived sediment accumulation rates, the magnetic susceptibility, C/N ratios and δ13C data evidenced background conditions at the lake until 1960s, when enhanced erosion related to the clearing of large forested areas at Los Tuxtlas promoted higher accumulation rates of a heavier and more magnetic sedimentary material. Recent sediments from Lago Verde were found enriched by Pb (26-fold natural concentration level [NCLs]) and moderately enriched by Cd > Cu > Zn and Hg (6-, 5-, 4- and 4-fold corresponding NCLs, respectively). The fluxes of Cu, Hg, Pb and Zn have significantly increased since 1940s, with peak ratios of total modern to pre-industrial fluxes of 11, 11, 19 and 49, respectively. The lake occupies a relatively pristine, non-industrialized basin, and therefore the increased metal fluxes might be related to long-distance aeolian transport of trace metals.

  11. Residence times of surface water and particle-reactive 210Pb and 210Po in the East China and Yellow seas

    228,226Ra, 210Pb, and 210Po were measured in the surface waters of the East China and Yellow seas. Using mass balance equations for the Ra isotopes. The authors estimated the total flux of diffusion from sediments and desorption from suspended particles to be 0.1 dpm 226Ra cm-2 a-1 and 1 dpm 228Ra cm-2 a-1, and residence times to be 2-3 years for the waters on the East China Sea Shelf and 5-6 years for Yellow Sea waters. Box-model calculations yielded generally congruent scavenging residence times for 210Pb and 210Po in the waters of ∼2 months on the shelf and ∼7 months in the Kuroshio Current. These suggest that reactive heavy metals and pollutants discharged through rivers from the continent to the East Asian continental shelf are largely deposited on the bottom sediments prior to transport to the pelagic ocean by lateral mixing

  12. Evaluation of occupational exposure in a underground coal mine by environmental measures of 222Rn and in vivo measurements of 210Pb in bones

    A radiological survey performed in an underground coal mining in the State of Parana, southern Brazil, has indicated the occurrence of high levels of concentration of radon and its decay products. The levels of 222Rn concentration measured in the basement of this mine, in the period from 1999 to 2003 ranged from 2000 to 7000 Bq m-3. It is estimated, for these workers, an average annual exposure of 2.1 WLM ranging from 0.2 to 7.2 WLM. A retrospective mortality study conducted with 2856 miners of this mining indicated a risk of lung cancer mortality greater than the one expected for the male population of the State. In this study the cumulative exposure to radon cannot be estimated since there was no radon measures in other periods. In this way, the cumulative exposure can be evaluated by through 210Pb activities monitored in the skeleton. The measures of 210Pb in skeleton ranged from 83 to 164 Bq, indicating that these workers were significantly exposed to 222Rn. These results show that cumulative exposure to radon has been higher than estimated based on recent measures of the activity concentration of radon in the workplace and is compatible with the risk determined in the epidemiological study

  13. Naturally occurring radioactive materials in the gas and oil industry. Origin, transport and deposition of stable lead and 210Pb from Dutch gas reservoirs

    Chapter 1 of this thesis provides the reader with background information on the title subject (abbreviated as NORM). Based on an extensive literature search, this chapter deals with general aspects of the natural decay series, the history of oil and gas NORM, identifies the most relevant radionuclides, and investigates geochemical aspects of oil and gas NORM. Special attention is paid to the Netherlands and adjacent southern North Sea area. Focus of this thesis, production of stable Pb and 210Pb with natural gas, was based on the conclusions of this literature search and on the encounter of 210Pb-bearing scales in Dutch gas production facilities. Where relevant, results from this study are included in chapter 1. In Chapter 2 the distribution of NORs in Dutch Rotliegend and Kupferschiefer sediments is studied, in order to identity the origin of 210Pb produced from Dutch gas reservoirs. In addition, a mechanism is proposed for the selective mobilisation of 210Pb from the reservoir sediments. Chapter 3 comprises a study on stable Pb in Dutch and German Rotliegend and Kupferschiefer sediments. A sequential extraction method is used to establish the distribution of Pb over five mineral phases in the sediments. Bulk chemistry, Pb distribution and stable Pb isotope signatures of the sediments are used to investigate whether Pb in Dutch Rotliegend gas reservoir brines can have originated from the Rotliegend sediments themselves. Experimental determination of the solubilities of Pb and water in methane is studied in Chapter 4, in order to see whether enough Pb can be transported in a water saturated gas phase to explain the occurrence of Pb mineral deposits in gas production facilities where no reservoir brines are coproduced with natural gas. Solubilities are compared with observed Pb concentrations in Dutch natural gas production samples, and some remarks are made on the speciation of Pb in the hydrocarbon gas phase. In Chapter 5, preliminary results are reported on the

  14. Ultrasonic Extraction and TLC Determination of Glyphosate in the Spiked Red Soils

    Sandra Babić

    2005-09-01

    Full Text Available Pesticides that get into soil bind mostly to its solid phase by physical or chemical processes. In the valley of the Neretva River the use of herbicides, especially of glyphosate is widespread and sometimes uncontrolled. In this work ultrasonic solvent extraction (USE followed by thin-layer chromatography (TLC was applied for determining glyphosate presence in soil. The experiments were conducted with two characterised soil types. The impact of soil composition on extraction efficiency is discussed. Chemical analysis showed that soil 1 contained much more iron and aluminium oxides than soil 2, which was richer in humic substances. Low glyphosate efficiency (ca 44 % in both soils could be attributed either to its binding to iron and aluminium oxides (soil 1, or to chemisorption on humic macromolecules (soil 2.

  15. Determination of 210Pb, 210Po, 226Ra, 228Ra and uranium isotopes in drinking water in order to comply with the requirements of the EU ‘Drinking Water Directive.

    Vasile, M; Loots, H; Jacobs, K; Verheyen, L; Sneyers, L; Verrezen, F; Bruggeman, M

    2016-03-01

    The European Union published in 2013 a new Drinking Water Directive with stricter requirements for measuring natural radioactivity. In order to adhere to this, a method for sequential separation of 210Pb, 210Po, 238U and 234U in drinking water was applied using UTEVA® and Sr resins. Polonium-210, 238U and 234U were quantified using alpha-particle spectrometry and 210Pb using liquid scintillation counting. Radium-226 and 228Ra were determined using 3M Empore Radium RAD Disks, and their quantification was done using a Quantulus™ 1220 liquid scintillation counter. PMID:27358946

  16. Mass accumulation rates and fallout radionuclides 210Pb, 137Cs and 241Am inventories determined in radiometrically dated abyssal sediments of the Black Sea

    Five abyssal (deep-sea) sediment cores collected during the two international cruises on R/V 'Professor Vodyanitskiy' (RADEUX-1998 and RADEUX-2000) in the framework of the Regional Technical Co-operation Project RER/2/003 'Marine Environmental Assessment in the Black Sea Region' were subjected to detailed radiometric analysis. The sediments were dated using the radionuclides 210Pb, 137Cs and 241Am and the results used to calculate a number of key parameters, e.g. radionuclide inventories, fluxes and sediment accumulation rates. The sediment cores were collected using a MARK II-400 multi-corer (Bowers and Connelly) in both Western and Eastern sub-basins of the Black Sea. The cores were sliced on board with a resolution of 0.2-0.4 cm for the top 5 cm and 1-5 cm downward using an extruder that was specially designed to prevent loss of the uppermost fluff-layer, possible down-smearing and interlayer cross-contamination of the sediment. Dry bulk density (DBD) and cumulative dry mass (CDM) were calculated on a salt-free basis using direct determination of the salt contribution to the dry mass of the sediment. Calculations showed that in the near surface sediments, and particularly in the top fluff-layer, the salt dissolved in pore-water contributed up to 30-60% of the mass of dried sediments. Neglecting this correction could cause an erroneous interpretation of the 210Pb activity profile, resulting in overestimation of both the average sedimentation rate and its recent temporal changes. Sediment samples were analysed for 210Pb, 226Ra, 137Cs and 241Am by direct gamma assay in UHMI after 3 weeks equilibration in hermetically sealed plastic holders, using an EG and G Ortec (Ametek) HPGe GWL series well-type coaxial low background intrinsic germanium detector. Correction was made for the effect of self-absorption of low energy γ-rays within the sample using attenuation parameters determined in. Chronostratigraphical analysis of the data and sediment age calculation have

  17. Two-dimensional model for soil electrokinetic remediation of heavy metals. Application to a copper spiked kaolin.

    Vereda-Alonso, Carlos; Miguel Rodríguez-Maroto, José; García-Delgado, Rafael A; Gómez-Lahoz, César; García-Herruzo, Francisco

    2004-02-01

    A two-dimensional numerical model has been developed to simulate the electrokinetic remediation of soils contaminated with heavy metals and has been validated using laboratory experiments performed with a copper spiked kaolin. The model divides the soil into compartments in a Cartesian grid and a non-conductivity barrier encloses the considered area. Basically, it consists in two main parts clearly distinguishable. The first part describes the electromigration phenomenon in the soil, which is represented by a set of electric resistors, following the Cartesian grid and using Kirchoff's laws of electricity to calculate the voltage drop distribution in the considered area. The second part describes the chemical equilibrium process between the heavy metal and the soil, assuming local equilibrium conditions within the compartments. A good agreement was obtained between the lab scale experimental assays and the model predictions. The model has also been used to examine the effect of the electrolyte neutralization within the scope of the acid-enhanced electrokinetic method. These simulations have foreseen problems related with the system evolution, which would not arise under one-dimensional geometries and are due to the changes of the potential distribution in the two-dimensional arrangement where some kind of short circuit arises, ultimately leading to a decrease of the system efficiency. PMID:14637347

  18. Monte Carlo validation of the self-attenuation correction determination with the Cutshall transmission method in 210Pb measurements by gamma-spectrometry

    The accuracy of estimation of the self-attenuation correction Cs with the Cutshall transmission method in 210Pb measurements by gamma-spectrometry was assessed using the Monte Carlo method. The Cutshall method overestimates the correction for samples with linear attenuation coefficient at 46.5 keV higher than that of the standard and underestimates it in the opposite case. The highest bias was found for thick samples. Cs,Cuts/Cs ratio grows linearly with sample linear attenuation coefficient. - Highlights: • The Cutshall method enables to determine self-attenuation correction experimentally. • The Cutshall method was validated by Monte Carlo simulations. • The Cutshall method provides systematically inaccurate Cs correction values. • The bias depends on relation between attenuation properties of sample and standard. • The highest bias was found for thick samples

  19. Cluster and factor analysis methods in the study of data on concentrations of 210Pb, 210Bi, 210Po and a number of stable elements in atmospheric aerosols

    We have performed cluster and factor analyses of results of determinations of the content of long-lived radon decay products (210Pb, 210Bi, 210Po) and 15 stable elements in atmospheric aerosols of the air near the surface. Using cluster analysis, we have isolated the test samples which are substantially different from the rest. Analysis of the factor loadings for a homogeneous group of filters has shown specificity in the behavior of the long-lived radon decay products and their strong intercollection. We have shown the absence of a number of technogenetic sources of nuclides of this group in the studied region. We note a correlation between the factor determining the variability of the long-lived radon decay products and the factor determining the content of stable lead and the mineral component

  20. Uranium-series radionuclides as tracers of geochemical processes in Long Island Sound. [Natural /sup 210/Pb tracer study of estuarine geochemistry

    Benninger, L.K.

    1976-05-01

    An estuary can be visualized as a membrane between land and the deep ocean, and the understanding of the estuarine processes which determine the permeability of this membrane to terrigenous materials is necessary for the estimation of fluxes of these materials to the oceans. Natural radionuclides are useful probes into estuarine geochemistry because of the time-dependent relationships among them and because, as analogs of stable elements, they are much less subject to contamination during sampling and analysis. In this study the flux of heavy metals through Long Island Sound is considered in light of the material balance for excess /sup 210/Pb, and analyses of concurrent seston and water samples from central Long Island Sound are used to probe the internal workings of the estuary.

  1. Populational exposure to 210Pb and 210Po in two cities with various industrial activities in the south-west of Romania

    In the present work, we proposed to estimate the contribution of the thermal power plants (TPP) relying in fossil fuel to the modification of the natural radioactive background and implicitly to the population's exposure in two urban centers - district residences - Timisoara and Deva. In the range of natural radioelements released in the atmosphere we considered as critical, 220Pb and 210Po for the following reasons: (i) radiolead is one of the long lived daughters of 222Rn in secular equilibrium with its daughter 210Bi. It is a beta active hard element, generator of Typo, an alpha active element with high energy. 210Pb, and 210Po are in the group of very high radiotoxicity; 210Bi high radiotoxicity; (ii) during the technological process of coal combustion of thermal power plants, there take place an accumulation of radiolead in the fly ash by a concentration rate of about 3 to 50. (author)

  2. Why would we use the Sediment Isotope Tomography (SIT) model to establish a 210Pb-based chronology in recent-sediment cores?

    After half a century, the use of unsupported 210Pb (210Pbexc) is still far off from being a well established dating tool for recent sediments with widespread applicability. Recent results from the statistical analysis of time series of fluxes, mass sediment accumulation rates (SAR), and initial activities, derived from varved sediments, place serious constraints to the assumption of constant fluxes, which is widely used in dating models. The Sediment Isotope Tomography (SIT) model, under the assumption of non post-depositional redistribution, is used for dating recent sediments in scenarios in that fluxes and SAR are uncorrelated and both vary with time. By using a simple graphical analysis, this paper shows that under the above assumptions, any given 210Pbexc profile, even with the restriction of a discrete set of reference points, is compatible with an infinite number of chronological lines, and thus generating an infinite number of mathematically exact solutions for histories of initial activity concentrations, SAR and fluxes onto the SWI, with these two last ranging from zero up to infinity. Particularly, SIT results, without additional assumptions, cannot contain any statistically significant difference with respect to the exact solutions consisting in intervals of constant SAR or constant fluxes (both being consistent with the reference points). Therefore, there is not any benefit in its use as a dating tool without the explicit introduction of additional restrictive assumptions about fluxes, SAR and/or their interrelationship. - Highlights: • The 210Pb-based method for dating recent sediments is of a widespread use. • Recent results limit the use of the simplifying assumption of constant fluxes. • SIT model claims to solve scenarios where fluxes and SAR independently vary with time. • The paper shows how SIT model lacks of sound physical basis. • A dating tool is only possible by introducing additional restrictive assumptions

  3. Deposition flux of Zn and Cr at the Cisadane estuary derived from 210Pb unsupported profile and 5 years flood-storm cycle

    The measurement of the depth profile of 210Pb unsupported and heavy metals within the core sediment samples were conducted at the Cisadane estuary at 2002 year. The two sediment cores were taken at the Tanjung Burung and Tiang Sampan estuary; respectively. The 210Pb unsupported depth profile could be used for estimating the sedimentation rate, and for estimating deposition flux of Zn and Cr based on 5 years cycle of time. The sedimentation rates of dry sediment at the Tanjung Burung estuary were 4.142 g/cm2/yr, 2.518 g/cm2/yr and 1.27 g/cm2/yr in periods of 1997- 2002, 1992-1997 and 1987-1992; respectively. The sedimentation rates of dry sediment at the Tiang Sampan estuary were 3.626 g/cm2/yr, 2.8 g/cm2/yr and 1.41 g/cm2/yr in periods of 1997-2002, 1992-1997 and 1987-1992. Deposition flux of Zn : Cr at the Tanjung Burung estuary were 4.867 g/m2/yr : 0.9 g/m2/yr, 3.515 g/m2/yr : 0.69 g/m2/yr and 1.363 g/m2/yr : 0.2 g/m2/yr; in periods of 1997- 2002, 1992-1997 and 1987-1992; respectively. Deposition flux of Zn:Cr at the Tiang Sampan estuary were 3.368 g/m2/yr : 0.703 g/m2/yr, 2.814 g/m2/yr : 0.574 g/m2/yr and 1.593 g/m2/yr : 0.303 g/m2/yr; in periods of 1997- 2002, 1992-1997 and 1987-1992; respectively. (author)

  4. Evaluation of the occupational exposure in a underground coal mine through environmental measurements of {sup 222}Rn and bone in vivo measurements of {sup 210} Pb; Avaliacao da exposicao ocupacional em uma mina subterranea de carvao atraves de medidas ambientais de {sup 222}Rn e medidas in vivo de {sup 210}Pb no osso

    Dantas, A.L.A.; Veiga, L.H.S.; Dantas, B.M.; Melo, V.P. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)]. E-mail: adatnas@ird.gov.br

    2005-03-15

    In this paper the radon cumulative exposure could not be calculated radon measurement in other periods were not available. Being so, the accumulated exposure was evaluated through the activities of {sup 210} Pb monitored in the skeletal. Those measures covered a range of 83 to 164 Bq, indicating that those workers were significant exposed to {sup 222} Rn. These results indicate that the radon accumulated exposure has been greater than the estimated based on the recent measurements of the radon activity concentration at the work local and is compatible with the risk determined in the epidemiological study.

  5. Data base structure and Management for Automatic Calculation of ''210 Pb Dating Methods Applying Different Models; Estructura de la Base de Datos y Modo de Operacion para Realizar el Calculo Automatizado de Datacion mediante ''210 Pb Aplicando Diversos Modelos

    Gasco, C.; Anton, M. P.; Ampudia, J.

    2003-07-01

    The introduction of macros in trie calculation sheets allows the automatic application of various dating models using unsupported ''210 Pb data from a data base. The calculation books the contain the models have been modified to permit the implementation of these macros. The Marine and Aquatic Radioecology group of CIEMAT (MARG) will be involved in new European Projects, thus new models have been developed. This report contains a detailed description of: a) the new implement macros b) the design of a dating Menu in the calculation sheet and c) organization and structure of the data base. (Author) 4 refs.

  6. Prediction of mono- and polycyclic aromatic hydrocarbon degradation in spiked soils using cyclodextrin extraction

    In this study, an aqueous-based hydroxypropyl-β-cyclodextrin (HPCD) extraction technique was assessed for its capacity to determine the microbially degradable fraction of mono- and polycyclic aromatic hydrocarbons in four dissimilar soils. A linear relationship (slope = 0.90; R 2 = 0.89), approaching 1:1 between predicted and observed phenanthrene mineralization, was demonstrated for the cyclodextrin extraction; however, the water only extraction underestimated the microbially available fraction by a factor of three (slope = 3.35; R 2 = 0.64). With respect to determining the mineralizable fraction of p-cresol in soils, the cyclodextrin extraction (slope = 0.94; R 2 = 0.84) was more appropriate than the water extraction (slope = 1.50; R 2 = 0.36). Collectively, these results suggested that the cyclodextrin extraction technique was suitable for the prediction of the mineralizable fraction of representative PAHs and phenols present in dissimilar soils following increasing soil-contaminant contact times. The assessment of the microbial availability of contaminants in soils is important for a more representative evaluation of soil contamination. - An aqueous-based HPCD extraction technique was more appropriate than the water extraction in prediction of the mineralizable fraction of phenanthrene and p-cresol present in a range of dissimilar soils

  7. Effect of Soil Filtration and Ozonation in the Change of Baseline Toxicity in Wastewater Spiked with Organic Micro-pollutants

    Gan, Alexander

    2012-07-01

    Bioassays for baseline toxicity, which measure toxicants’ non-specific effects, have been shown in previous studies to effectively correlate with the increased presence of pharmaceuticals, personal care products, endocrine-disrupting compounds, and other synthetic organics in treated sewage effluent. This study investigated how the baseline toxicity of anthropogenic compounds-spiked wastewater changed during the treatment of biofiltration and ozone oxidation, as measured by the bioluminescence inhibition of the Vibrio fischeri bacterium. The water quality parameters of dissolved organic carbon, seven common anions, and fluorescence spectroscopy were used to corroborate and collate with the toxicity results. Water quality was evaluated on two bench-scale soil filtration columns, which were configured for pre-ozonation and post-ozonation. Both systems’ soil aerobically removed similar amounts of dissolved organic carbon, and the reduction ranged between 57.7% and 62.1% for the post-ozonation and pre-ozonation systems, respectively. Biological removal of DOC, protein-like, humic-like, and soluble microbial product-like material was highest in the first 28.5 cm of each 114 cm-long system. While bioluminescence inhibition showed that ozonation was effective at lowering baseline toxicity, this study’s bioassay procedure was a very poor indicator of soil filtration treatment; both system’s effluents were significantly more toxic than their non-ozonated influents.

  8. Synthesis, characterization and role of zero-valent iron nanoparticle in removal of hexavalent chromium from chromium-spiked soil

    Chromium is an important industrial metal used in various products/processes. Remediation of Cr contaminated sites present both technological and economic challenges, as conventional methods are often too expensive and difficult to operate. In the present investigation, Zero-valent iron (Fe0) nanoparticles were synthesized, characterized, and were tested for removal of Cr(VI) from the soil spiked with Cr(VI). Fe0 nanoparticles were synthesized by the reduction of ferric chloride with sodium borohydride and were characterized by UV–Vis (Ultra violet–Visible) and FTIR (Fourier transform infrared) spectroscopy. The UV–Vis spectrum of Fe0 nanoparticles suspended in 0.8% Carboxymethyl cellulose showed its absorption maxima at 235 nm. The presence of one band at 3,421 cm−1 ascribed to OH stretching vibration and the second at 1,641 cm−1 to OH bending vibration of surface-adsorbed water indicates the formation of ferrioxyhydroxide (FeOOH) layer on Fe0 nanoparticles. The mean crystalline dimension of Fe0 nanoparticles calculated by XRD (X-ray diffraction) using Scherer equation was 15.9 nm. Average size of Fe0 nanoparticles calculated from TEM (Transmission electron microscopy) images was found around 26 nm. Dynamic Light Scattering (DLS) also showed approximately the same size. Batch experiments were performed using various concentration of Fe0 nanoparticles for reduction of soil spiked with 100 mg kg−1 Cr(VI). The reduction potential of Fe0 nanoparticles at a concentration of 0.27 g L−1 was found to be 100% in 3 h. Reaction kinetics revealed a pseudo-first order kinetics. Factors like pH, contact time, stabilizer, and humic acid facilitates the reduction of Cr(VI).

  9. Do drying and rewetting cycles modulate effects of sulfadiazine spiked manure in soil?

    Jechalke, Sven; Radl, Viviane; Schloter, Michael; Heuer, Holger; Smalla, Kornelia

    2016-05-01

    Naturally occurring drying-rewetting events in soil have been shown to affect the dissipation of veterinary antibiotics entering soil by manure fertilization. However, knowledge of effects on the soil microbial community structure and resistome is scarce. Here, consequences of drying-rewetting cycles on effects of sulfadiazine (SDZ) in soil planted withDactylis glomerataL. were investigated in microcosms. Manure containing SDZ or not was applied to the pregrown grass and incubated for 56 days in a climate chamber. Water was either added daily or reduced during two drying events of 7 days, each followed by a recovery phase. Total community DNA was analyzed to reveal the effects on the bacterial community structure and on the abundance ofsul1,sul2,intI1,intI2,qacE+qacEΔ1,traNandkorBgenes relative to 16S rRNA genes. 16S rRNA gene-based DGGE fingerprints indicated that drying-rewetting cycles modulated the effects of SDZ on the bacterial community structure in the soil. Furthermore, the SDZ treatment increased the relative abundance of sulfonamide resistance and integrase genes compared to the control. However, this increase was not different between moisture regimes, indicating that drying-rewetting had only a negligible effect on the selection of the resistome by SDZ in the manured soil. PMID:27053757

  10. Determination of 226Ra, 228Ra and 210Pb in NORM products from oil and gas exploration: Problems in activity underestimation due to the presence of metals and self-absorption of photons

    Typical calibration of solid environmental samples for the determination of 226Ra, 228Ra and 210Pb entails the use of standard reference materials which have a very similar matrix. However, TENORM samples from the oil and gas exploration contain unusually high amounts of calcium, strontium and barium which can severely attenuate the photons of 210Pb and 226Ra with their characteristic 46.1 keV and 186.2 keV gamma-rays, respectively and to some extent 228Ra with the characteristic gamma-rays of 911.2 keV and 969.0 keV. We used neutron activation analysis to evaluate the content of TENORM for calcium, barium and strontium and then used a software program SELABS to determine the self-absorption. Our results confirm that even in Petrie® containers with small dimensions the 210Pb can be underestimated by almost by a factor of four while 226Ra can be underestimated by 5%. The 228Ra activities are virtually unaffected due to the higher energy gamma-rays. However, the implications for TENORM studies that employ large Marinelli® containers having sample sizes between 0.25 and 1.0 L may be severely compromised by the presence of high Z elements in elevated concentrations. The usual spectral interferences on 226Ra, 228Ra and 210Pb coming from other radionuclides in the 234U, 235U and 238U decay chains are virtually nonexistent due the very high activity levels of 226Ra, 228Ra and 210Pb in the tens of thousands of Bq/kg

  11. Evaluation of occupational exposure in a underground coal mine by environmental measures of {sup 222}Rn and in vivo measurements of {sup 210}Pb in bones; Avaliacao da exposicao ocupacional em uma mina subterranea de carvao atraves de medidas ambientais de {sup 222}Rn e medidas in vivo de {sup 210}Pb no osso

    Dantas, A.L.A.; Veiga, L.H.S.; Dantas, B.M.; Melo, V.P. [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2005-07-01

    A radiological survey performed in an underground coal mining in the State of Parana, southern Brazil, has indicated the occurrence of high levels of concentration of radon and its decay products. The levels of {sup 222}Rn concentration measured in the basement of this mine, in the period from 1999 to 2003 ranged from 2000 to 7000 Bq m{sup -3}. It is estimated, for these workers, an average annual exposure of 2.1 WLM ranging from 0.2 to 7.2 WLM. A retrospective mortality study conducted with 2856 miners of this mining indicated a risk of lung cancer mortality greater than the one expected for the male population of the State. In this study the cumulative exposure to radon cannot be estimated since there was no radon measures in other periods. In this way, the cumulative exposure can be evaluated by through {sup 210}Pb activities monitored in the skeleton. The measures of {sup 210}Pb in skeleton ranged from 83 to 164 Bq, indicating that these workers were significantly exposed to {sup 222}Rn. These results show that cumulative exposure to radon has been higher than estimated based on recent measures of the activity concentration of radon in the workplace and is compatible with the risk determined in the epidemiological study.

  12. Experimental determinations of soil copper toxicity to lettuce (Lactuca sativa) growth in highly different copper spiked and aged soils

    Christiansen, Karen Søgaard; Borggaard, Ole K.; Holm, Peter Engelund;

    2015-01-01

    H (ECEC), and at pH 7 (CEC7), soil organic carbon, clay content, and electric conductivity as well as the distribution coefficient (Kd) calculated as the ratio between total soil Cu and water-extractable Cu did not correlate significantly with pEC50(Cu2+). Consequently, Cu toxicity, expressed...

  13. Effect of Wetting-Drying Cycles on Redistribution of Lead in Some Semi-Arid Zone Soils Spiked with a Lead Salt

    H.KHODAVERDILOO; M.RAHMANIAN; S.REZAPOUR; S.GHORBANI DASHTAKI; H.HADI; F.X.HAN

    2012-01-01

    Mobility and bioavailability of lead (Pb) could be affected considerably by soil physicochemical properties; however,less is known about the effect of Pb levels and aging time.This study was conducted to evaluate the effects of Pb levels and wetting-drying (WD) cycles on distribution and bioavailability of Pb in three semi-arid zone soils treated with different levels of Pb(NO3)2.Wetting-drying cycles simulated the actual field irrigation in the semi-arid soils.A soil with a long history of Pb contamination was also taken as a reference soil.The soils were spiked with various levels of Pb and incubated under WD cycles for 160 d.Sequential extractions and batch sorption experiments were performed to assess the fractionation of Pb in the spiked soils.Redistribution index (Uts) and reduced partitioning parameter (IR) were applied to semi-quantify the distribution of Pb in the spiked soils.A small amount of Pb sorbed was desorbed by the soils,indicating a strong and irreversible binding of Pb in the studied soils.Contribution of carbonate-bound (Car) and residual (Res) Pb fractions to the total Pb of the soils was more than 97%.The Car,soluble plus exchangeable (SE),and organic matter-bound (OMB) fractions of Pb were transferred to the Res fraction under the WD cycles.The IR and Uts values were influenced by Pb loading levels and WD; therefore,the Pb lability and/or redistribution pattern could semi-quantitatively be assessed via these parameters.At the end of the experiment,the IR and Uts values for the Pb salt-spiked soils did not show the quasiequilibrium state.The lability of Pb in the soils decreased with increasing incubation time and showed a strong dependence on Pb levels and soil chemical composition.WD cycles significantly affected the overall lability of Pb in soils through influencing the redistribution of Pb among solid-phase components.

  14. Evaluation of recent trends of sedimentation in Indian lakes of western Himalayan region using 210Pb and 137Cs dating techniques

    In the present study, environmental 210Pb and 137Cs dating techniques were employed to determine the recent sedimentation rates of Nainital, Bhimtal, Sat-tal, Naukuchiyatal and Mansar and Dal-Nagin lake of Western Himalayan region. The expected useful life of these lakes have also been estimated. These studies are part of the project funded by Government of India. Three to five sediment cores were collected from the each lakes namely Nainital, Bhimtal, Naukuchiyatal, Sat-tal and Mansar and 14 sediment cores from Dal-Nagin lake using a gravity corer. The sediment cores ranging from 19 to 53 cm in length were sliced at 2 cm intervals. Sliced core sections were brought to laboratory and subjected to various physical and chemical process before measuring 137Cs and 210Pb activities. After the chemical treatment of the sliced samples, the extracted solution containing 210Pb was allowed to stay for a period of one month as 4 to 5 half lives are sufficient for this purpose for getting 210Bi in secular equilibrium with 210Pb activity. The 210Pb activity was measured in terms of beta radiations using 210Bi which is its daughter product and has half life of ∼5 days. The activity of 210Bi was measured using a Ultra Low level Liquid Scintillation spectrometer and CRS model was applied for estimating rates of sedimentation. The 137Cs activity in each section was determined by gamma counting in the oven-dried samples using Hyper Pure Germanium detector coupled with a 4096 channel multichannel analyser system. A 137Cs standard, having essentially the same geometry and density was used. The detection limit for 137Cs by this method is 0.25 mBq.g-1 and the standard counting error was less than 10% in the core sections. The sedimentation rate varies between 1.74 cm/yr to 3.87 cm/yr (weighted mean 1.44 ± 0.18 cm/y) in Bhimtal lake, 0.38 cm/yr to 0.95 cm/yr (weighted mean 0.74 ± 0.04 cm/y) in Naukuchiyatal lake, 0.54 cm/yr to 1.55 cm/yr (weighted mean 0.84 ± 0.05 cm/y) in Sat

  15. Bioavailability of Zn in ZnO nanoparticle-spiked soil and the implications to maize plants

    Liu, Xueqin [Southwest University, College of Resources and Environment (China); Wang, Fayuan, E-mail: wfy1975@163.com; Shi, Zhaoyong [Henan University of Science and Technology, Agricultural College (China); Tong, Ruijian [Luoyang Normal University, Life Science Department (China); Shi, Xiaojun, E-mail: shixj@swu.edu.cn [Southwest University, College of Resources and Environment (China)

    2015-04-15

    Little is known about the relationships between Zn bioavailability in ZnO nanoparticle (NP)-spiked soil and the implications to crops. The present pot culture experiment studied Zn bioavailability in soil spiked with different doses of ZnO NPs, using the diethylenetriaminepentaacetic acid (DTPA) extraction method, as well as the toxicity and Zn accumulation in maize plants. Results showed that ZnO NPs exerted dose-dependent effects on maize growth and nutrition, photosynthetic pigments, and root activity (dehydrogenase), ranging from stimulatory (100–200 mg/kg) through to neutral (400 mg/kg) and toxic effect (800–3200 mg/kg). Both Zn concentration in shoots and roots correlated positively (P < 0.01) with ZnO NPs dose and soil DTPA-extractable Zn concentration. The BCF of Zn in shoots and roots ranged from 1.02 to 3.83 when ZnO NPs were added. In most cases, the toxic effects on plants elicited by ZnO NPs were overall similar to those caused by bulk ZnO and soluble Zn (ZnSO{sub 4}) at the same doses, irrespective of some significant differences suggesting a higher toxicity of ZnO NPs. Oxidative stress in plants via superoxide free radical production was induced by ZnO NPs at 800 mg/kg and above, and was more severe than the same doses of bulk ZnO and ZnSO{sub 4}. Although significantly lower compared to bulk ZnO and ZnSO{sub 4}, at least 16 % of the Zn from ZnO NPs was converted into DTPA-extractable (bioavailable) forms. The dissolved Zn{sup 2+} from ZnO NPs may make a dominant contribution to their phytotoxicity. Although low amounts of ZnO NPs exhibited some beneficial effects, the accumulation of Zn from ZnO NPs into maize tissues could pose potential health risks for both plants and human.

  16. Bioavailability of Zn in ZnO nanoparticle-spiked soil and the implications to maize plants

    Little is known about the relationships between Zn bioavailability in ZnO nanoparticle (NP)-spiked soil and the implications to crops. The present pot culture experiment studied Zn bioavailability in soil spiked with different doses of ZnO NPs, using the diethylenetriaminepentaacetic acid (DTPA) extraction method, as well as the toxicity and Zn accumulation in maize plants. Results showed that ZnO NPs exerted dose-dependent effects on maize growth and nutrition, photosynthetic pigments, and root activity (dehydrogenase), ranging from stimulatory (100–200 mg/kg) through to neutral (400 mg/kg) and toxic effect (800–3200 mg/kg). Both Zn concentration in shoots and roots correlated positively (P < 0.01) with ZnO NPs dose and soil DTPA-extractable Zn concentration. The BCF of Zn in shoots and roots ranged from 1.02 to 3.83 when ZnO NPs were added. In most cases, the toxic effects on plants elicited by ZnO NPs were overall similar to those caused by bulk ZnO and soluble Zn (ZnSO4) at the same doses, irrespective of some significant differences suggesting a higher toxicity of ZnO NPs. Oxidative stress in plants via superoxide free radical production was induced by ZnO NPs at 800 mg/kg and above, and was more severe than the same doses of bulk ZnO and ZnSO4. Although significantly lower compared to bulk ZnO and ZnSO4, at least 16 % of the Zn from ZnO NPs was converted into DTPA-extractable (bioavailable) forms. The dissolved Zn2+ from ZnO NPs may make a dominant contribution to their phytotoxicity. Although low amounts of ZnO NPs exhibited some beneficial effects, the accumulation of Zn from ZnO NPs into maize tissues could pose potential health risks for both plants and human

  17. Temporal evolution of natural radionuclides distributions {sup 238}U, {sup 234}Th, {sup 226}Ra, {sup 228}Ra, {sup 210}Pb and {sup 210}Po in the Bransfield strait, Antarctica peninsula; Evolucao temporal das distribuicoes dos radionuclideos naturais {sup 238}U, {sup 234}Th, {sup 226}Ra, {sup 228}Ra, {sup 210}Pb and {sup 210}Po no estreito de Bransfiel, peninsula Antartica

    Lapa, Flavia Valverde

    2013-07-01

    Research on the distribution of natural radionuclides in Antarctica is rare and thus, there is great interest in to know their occurrence and factors related to its mobilization, transference and accumulation in this extremely fragile environment. Natural radionuclides have been used intensively as tracers in the ocean, helping to better understand processes as sinking and particle resuspension, water masses mixture and oceanic circulation. {sup 234}Th (t½ = 24.1 days) is a particle-reactive radionuclide produced continuously in seawater by the decay of its soluble precursor conservative with salinity {sup 238}U (t½ = 4.5 10{sup 9} years). Since {sup 234}Th presents relatively short half-life, it is used to quantify processes that occur in temporal scale varying from days to weeks. The disequilibrium {sup 234}Th/{sup 238}U in the surface ocean has been applied to estimate carbon fluxes exported via sinking material. The flux of particles biologically productive out of the euphotic zone in the Southern Ocean has special attention due to its importance in the control of CO{sub 2} atmospheric concentrations. The radionuclides {sup 210}Pb (t½ = 22.3 years) and {sup 210}Po (t½ = 138 days) are also particle-reactive. The disequilibrium {sup 210}Po/{sup 210}Pb has been used to estimate fluxes of particles exported in the ocean in the time scale of weeks. The long-lived Ra isotopes, {sup 226}Ra (t½ = 1,600 years) and {sup 228}Ra (t½ = 5.75 years) are soluble in seawater, presenting unique properties that make them excellent tracers of water masses. This research work had the aim to study the distributions of natural radionuclides {sup 238}U, {sup 234}Th, {sup 22}'6Ra, {sup 22}'8Ra, {sup 210}Pb and {sup 210}Po in the Bransfield Strait during 2 samplings carried out in the 2011 Austral Summer (OPERANTAR XXIX and XXX). (author)

  18. Molecular level characterization of diatom-associated biopolymers that bind 234Th, 233Pa, 210Pb, and 7Be in seawater: A case study with Phaeodactylum tricornutum

    Chuang, Chia-Ying; Santschi, Peter H.; Xu, Chen; Jiang, Yuelu; Ho, Yi-Fang; Quigg, Antonietta; Guo, Laodong; Hatcher, Patrick G.; Ayranov, Marin; Schumann, Dorothea

    2015-09-01

    In order to investigate the importance of biogenic silica associated biopolymers on the scavenging of radionuclides, the diatom Phaeodactylum tricornutum was incubated together with the radionuclides 234Th, 233Pa, 210Pb, and 7Be during their growth phase. Normalized affinity coefficients were determined for the radionuclides bound with different organic compound classes (i.e., proteins, total carbohydrates, uronic acids) in extracellular (nonattached and attached exopolymeric substances), intracellular (ethylene diamine tetraacetic acid and sodium dodecyl sulfate extractable), and frustule embedded biopolymeric fractions (BF). Results indicated that radionuclides were mostly concentrated in frustule BF. Among three measured organic components, Uronic acids showed the strongest affinities to all tested radionuclides. Confirmed by spectrophotometry and two-dimensional heteronuclear single quantum coherence-nuclear magnetic resonance analyses, the frustule BF were mainly composed of carboxyl-rich, aliphatic-phosphoproteins, which were likely responsible for the strong binding of many of the radionuclides. Results from this study provide evidence for selective absorption of radionuclides with different kinds of diatom-associated biopolymers acting in concert rather than as a single compound. This clearly indicates the importance of these diatom-related biopolymers, especially frustule biopolymers, in the scavenging and fractionation of radionuclides used as particle tracers in the ocean.

  19. Activity concentration of 210Po and 210Pb, its contribution to the radiation dose and distribution coefficient in aquatic ecosystem of major rivers of coastal Karnataka

    Rivers are the major pathways for the transport of weathered materials from the land to the oceans. The geochemical studies on river waters provide an insight into the weathering process that control the distribution of elements in dissolved and particulate phases and their fluxes to the estuaries. Concentrations of natural series radionuclide in fresh water bodies are liable to be much more variable than those in the marine environment since they are heavily influenced by the local geochemistry of the watershed. The concentrations of radioactive materials vary from region to region and this variation is found to be significantly high in some areas. Some of the regions are rich with the flow of major rivers and estuaries of these rivers, and investigations of these riverine and estuarine aquatic environments would throw light on the transportation, distribution and enrichment mechanism of radionuclides. In this context, the activity of 210Po and 210Pb were measured in different matrices of aquatic ecosystem of the major rivers namely, Kali, Sharavathi and Netravathi river of Coastal Karnataka

  20. Application of 210Pb-derived sedimentation rates and dinoflagellate cyst analyses in understanding Pyrodinium bahamense harmful algal blooms in Manila Bay and Malampaya Sound, Philippines

    The number of areas affected by toxic harmful algal bloom (HAB) in the Philippines has been increasing since its first recorded occurrence in 1983. Thus far, HAB has been reported in about 20 areas in the Philippines including major fishery production areas. The HAB-causing organism (Pyrodinium bahamense var. compressum) produces a cyst during its life cycle. Pyrodinium cysts which are deposited in the sediment column may play a role in initiating a toxic bloom. 210Pb-derived sedimentation rate studies in the two important fishing grounds of Manila Bay and Malampaya Sound, Palawan have shown that Pyrodinium cysts may have been present in the sediment even before the first recorded toxic algal bloom in these areas. High sedimentation rates (approximately 1 cm/year) have been observed in the Northern and Western parts of Manila Bay. The results indicate that the sedimentation processes occurring in these bays would require subsurface cyst concentration analysis in evaluating the potential of an area to act as sea bed

  1. Radioanalytical assessment of sedimentation rates in Guajara Bay (Amazon Estuary, N Brazil). A study with unsupported 210Pb and 137Cs modeling

    Guajara Bay is an integral part of the Amazon Estuary system, and functions as the main receiver of urban and industrial wastes from the city of Belem, capital city of PA State (N Brazil). There is a lack of knowledge regarding quantitative measures of sedimentation, such as sedimentation rates, in the literature for this area of the Amazon Estuary. This study aimed the evaluation of recent (time range of 100 years) sedimentation rates in three sediment profiles collected in the coastal system of Guajara Bay with a radioanalytical approach of unsupported 210Pb and 137Cs modeling. The mean sedimentation rates for the cores obtained were 0.85 ± 0.12 cm year-1 for Anadim core, 1.02 ± 0.17 cm year-1 for Outeiro core and 0.53 ± 0.04 cm year-1 for Tucunduba core. With the use of three models of sedimentation rate models, it was observed that Anadim and Outeiro core presented constant sedimentation rates for the evaluated time range, but Tucunduba did not. This difference in sedimentation rates was probably due to their different sampling locations that present diverse hydrodynamic regime, with deposition of fine sediments in the upper area of the bay and stronger fluvial currents in the southernmost region. (author)

  2. Bioaccumulation and single and joint toxicities of penta-BDE and cadmium to earthworms (Eisenia fetida) exposed to spiked soils

    2010-01-01

    Bioaccumulation of penta-BDE(DE-71) in earthworms(Eisenia fetida) and the induced toxicities on the growth and reproduction of earthworms were investigated.All the major congeners in DE-71 could be bioaccumulated in earthworms and the concentration found in earthworms correlated to the spiked concentration in soil.DE-71 might inhibit the growth and reproduction of cocoons and juveniles of earthworms.The toxicities were dose dependent and increased with exposure time.Exposing earthworms to combination of DE-71 and Cd resulted in enhanced mortality and reduction of cocoons or juveniles in a synergistic mode.The presence of DE-71 may affect the relocation of Cd in earthworms.When the earthworms were exposed to Cd alone,Cd up-taken by earthworms was mainly partitioned in the cytosolic fraction.While DE-71 was present,Cd in the cytosolic fraction decreased significantly.It is perhaps that DE-71 inhibits the synthesis of matallothioneins,and then reduces the detoxification ability of earthworms.This is the first report about the toxicity of PBDEs to earthworms.The result would be useful for ecological risk assessment of PBDEs in terrestrial ecosystem.

  3. Collection of emanating 222Rn for the preparation of a 210Pb-210Po alpha-source and the building of a mobile random pulse and probability generator utilizing alpha-counting technique

    A random pulse and probability generator (RPG) has been developed utilizing the detection technique of alpha-particles as the random signal source. The collection technique for 222Rn emanated from natural uranium ore was examined for preparing highly pure 210Pb-210Po as an alpha source for RPG. The yield with a trap refrigerated by liquid nitrogen was observed to be above 99% for 222Rn collection. (author)

  4. Beryllium-7 and lead-210 chronometry of modern soil processes: The Linked Radionuclide aCcumulation model, LRC

    Landis, Joshua D.; Renshaw, Carl E.; Kaste, James M.

    2016-05-01

    Soil systems are known to be repositories for atmospheric carbon and metal contaminants, but the complex processes that regulate the introduction, migration and fate of atmospheric elements in soils are poorly understood. This gap in knowledge is attributable, in part, to the lack of an established chronometer that is required for quantifying rates of relevant processes. Here we develop and test a framework for adapting atmospheric lead-210 chronometry (210Pb; half-life 22 years) to soil systems. We propose a new empirical model, the Linked Radionuclide aCcumulation model (LRC, aka "lark"), that incorporates measurements of beryllium-7 (7Be; half-life 54 days) to account for 210Pb penetration of the soil surface during initial deposition, a process which is endemic to soils but omitted from conventional 210Pb models (e.g., the Constant Rate of Supply, CRS model) and their application to sedimentary systems. We validate the LRC model using the 1963-1964 peak in bomb-fallout americium-241 (241Am; half-life of 432 years) as an independent, corroborating time marker. In three different soils we locate a sharp 241Am weapons horizon at disparate depths ranging from 2.5 to 6 cm, but with concordant ages averaging 1967 ± 4 via the LRC model. Similarly, at one site contaminated with mercury (HgT) we find that the LRC model is consistent with the recorded history of Hg emission. The close agreement of Pb, Am and Hg behavior demonstrated here suggests that organo-metallic colloid formation and migration incorporates many trace metals in universal soil processes and that these processes may be described quantitatively using atmospheric 210Pb chronometry. The 210Pb models evaluated here show that migration rates of soil colloids on the order of 1 mm yr-1 are typical, but also that these rates vary systematically with depth and are attributable to horizon-specific processes of leaf-litter decay, eluviation and illuviation. We thus interpret 210Pb models to quantify (i) exposure

  5. Bioaccessibility of arsenic and cadmium assessed for in vitro bioaccessibility in spiked soils and their interaction during the Unified BARGE Method (UBM) extraction.

    Xia, Qing; Peng, Cheng; Lamb, Dane; Mallavarapu, Megharaj; Naidu, Ravi; Ng, Jack C

    2016-03-01

    Recent decades have seen a growing popularity of in vitro bioaccessibility being utilised as a screening tool in human health risk assessment. However the existing bioaccessibility studies only focus on single contaminant. Considering human are likely to ingest multi-contaminants, these contaminants could interact within human gastrointestinal tract which may lead to an increase or decrease in bioaccessibility. In this study, seven different types of soil were spiked with arsenic (As) or cadmium (Cd) and aged for one year. The effects of soil properties on the bioaccessibility were examined. Moreover, the interaction between As and Cd in simulated human digestive system was studied by mixing As-spiked soil with Cd-spiked soil of the same type during bioaccessibility test. Results shows the bioaccessibility of As ranged from 40 ± 2.8 to 95 ± 1.3% in the gastric phase and 16 ± 2.0 to 96 ± 0.8% in the intestinal phase whilst a significant difference was observed between Cd gastric bioaccessibility (72 ± 4.3 to 99 ± 0.8%) and intestinal bioaccessibility (6.2 ± 0.3 to 45 ± 2.7%). Organic carbon, iron oxide and aluminium oxide were key parameters influencing the bioaccessibility of As (gastric and intestinal phases) and Cd (intestinal phase). No interactions between As and Cd during bioaccessibility test were observed in any soils, which indicates As and Cd may age independently and did not interact while being solubilised during bioaccessibility test. Thus additive effect may be proposed when estimating the bioaccessibility of mixtures of independently-aged As and Cd in soils. PMID:26774311

  6. Spiking solvent, humidity and their impact on 2,4-D and 2,4-DCP extractability from high humic matter content soils.

    Merini, Luciano Jose; Cuadrado, Virginia; Giulietti, Ana María

    2008-05-01

    The 2,4-dichlorophenoxyacetic acid (2,4-D) is a hormone-like herbicide widely used in agriculture. Although its half life in soil is approximately two weeks, the thousands of tons introduced in the environment every year represent a risk for human health and the environment. Considering the toxic properties of this compound and its degradation products, it is important to assess and monitor the 2,4-D residues in agricultural soils. Furthermore, experiments of phyto/bioremediation are carried out to find economic and environmental friendly tools to restore the polluted soils. Accordingly, it is essential to accurately measure the amount of 2,4-D and its metabolites in soils. There is evidence that 2,4-D extraction from soil samples seriously depends on the physical and chemical properties of the soil, especially in those soils with high content of humic acids. The aim of this work was to assess the variables that influence the recovery and subsequent analysis of 2,4-D and its main metabolite (2,4-dichlorophenol) from those soils samples. The results showed that the recovery efficiency depends on the solvent and method used for the extraction, the amount and kind of solvent used for dissolving the herbicide and the soil water content at the moment of spiking. An optimized protocol for the extraction and quantification of 2,4-D and its main metabolite from soil samples is presented. PMID:18275981

  7. 210Pb-derived history of PAH and PCB accumulation in sediments of a tropical inner lagoon (Las Matas, Gulf of Mexico) near a major oil refinery

    Ruiz-Fernández, Ana Carolina; Sprovieri, Mario; Piazza, Rossano; Frignani, Mauro; Sanchez-Cabeza, Joan-Albert; Feo, Maria Luisa; Bellucci, Luca Giorgio; Vecchiato, Marco; Pérez-Bernal, Libia Hascibe; Páez-Osuna, Federico

    2012-04-01

    Concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in a sediment core from the tropical freshwater inner lagoon of Las Matas, near the petroleum industrial area of Minatitlán-Coatzacoalcos, in the Gulf of Mexico. A 210Pb-derived chronology was used to reconstruct the historical PAH and PCB accumulation in the site during one century (1906-2005). Both geochemical and sedimentological data indicated that a major change occurred in 1947 ± 4, including a shift to coarser sediments and a significant decrease of Al, Li, Fe, organic C and total N contents. This was likely due to the changes in hydrology caused by the confinement of Las Matas Lagoon due to the construction of the Trans-Isthmus road in 1946. PAHs in these samples show relatively low concentrations (259-1176 ng g-1), and the congener relative abundances indicate the influence of pyrogenic (petroleum combustion) sources. Total PCB concentrations in the sediments ranged from 24 to 77 ng g-1, and are composed by low chlorinated PCBs, with 3- and 4-CB as the prevalent species (51-65% and 29-40%, respectively). PAHs and PCBs were detected at depths corresponding to the early 1900s, when Minatitlán refinery started operations, although their time evolution appears to be influenced by different accumulation processes. The PCB background is most likely produced by the combustion of natural organic matter, and an industrial contribution can be recognized when normalizing with OC contents. We concluded that atmospheric deposition is the most significant source of PAHs and PCBs for this water body. This study also provided evidence of the alteration of the wetlands surrounding this industrial area due to urbanization; the fragmentation and alteration of Las Matas Lagoon hydrology contributes to the gradual loss of the wetlands in the zone.

  8. Variations of 210Po and 210Pb in various marine organisms from Western English Channel: contribution of 210Po to the radiation dose

    Measurements of 210Po were carried out in various marine matrices (mussels, oysters, seaweed, fish, and abalones) and in seawater at several points along the French coast, over a period of 2 years (2003-2005). These measurements contribute to a better knowledge of this element, since few recent data exist for the French coast. Marked seasonal variations have been revealed in some species and there are differences according to the way of life of these species. Activities in mussels (Mytilus edulis) and oysters (Crassostrea gigas) are similar and varying between 90 and 600 Bq kg-1 (d.w.). Activities in macroalgae (Fucus serratus) are lowest, between 4 and 16 Bq kg-1 (d.w.). In oyster, abalone (Haliotis tuberculata) and fish (Solea solea, Sparus sp.), the strongest activities are measured in the digestive glands, the gills and the gonads. 210Po/210Pb ratios in all cases have values of more than one for all species. From a significant number of measurements, CFs were calculated for seaweed (between 4.6 x 103 and 5.0 x 103) and for molluscs, with highest CFs (>105) found for the digestive gland and gills of the oysters, the digestive gland of the abalones and the liver of fish. Finally, the activities measured have made it possible to estimate the internal dose from chronic exposure due to 210Po received by the marine organisms (0.05 μG h-1 for macroalgae, between 0.70 and 1.5 μG h-1 for mussels and oyster), and the contribution of seafood to the dose received by humans (46-129 μSv y-1)

  9. Variations of {sup 210}Po and {sup 210}Pb in various marine organisms from Western English Channel: contribution of {sup 210}Po to the radiation dose

    Connan, O. [Institut de Radioprotection et de Surete Nucleaire, Laboratoire de Radioecologie de Cherbourg-Octeville, IRSN/DEI/SECRE/LRC, Rue Max Pol Fouchet, 50130 Cherbourg-Octeville (France)], E-mail: olivier.connan@irsn.fr; Germain, P.; Solier, L.; Gouret, G. [Institut de Radioprotection et de Surete Nucleaire, Laboratoire de Radioecologie de Cherbourg-Octeville, IRSN/DEI/SECRE/LRC, Rue Max Pol Fouchet, 50130 Cherbourg-Octeville (France)

    2007-10-15

    Measurements of {sup 210}Po were carried out in various marine matrices (mussels, oysters, seaweed, fish, and abalones) and in seawater at several points along the French coast, over a period of 2 years (2003-2005). These measurements contribute to a better knowledge of this element, since few recent data exist for the French coast. Marked seasonal variations have been revealed in some species and there are differences according to the way of life of these species. Activities in mussels (Mytilus edulis) and oysters (Crassostrea gigas) are similar and varying between 90 and 600 Bq kg{sup -1} (d.w.). Activities in macroalgae (Fucus serratus) are lowest, between 4 and 16 Bq kg{sup -1} (d.w.). In oyster, abalone (Haliotis tuberculata) and fish (Solea solea, Sparus sp.), the strongest activities are measured in the digestive glands, the gills and the gonads. {sup 210}Po/{sup 210}Pb ratios in all cases have values of more than one for all species. From a significant number of measurements, CFs were calculated for seaweed (between 4.6 x 10{sup 3} and 5.0 x 10{sup 3}) and for molluscs, with highest CFs (>10{sup 5}) found for the digestive gland and gills of the oysters, the digestive gland of the abalones and the liver of fish. Finally, the activities measured have made it possible to estimate the internal dose from chronic exposure due to {sup 210}Po received by the marine organisms (0.05 {mu}G h{sup -1} for macroalgae, between 0.70 and 1.5 {mu}G h{sup -1} for mussels and oyster), and the contribution of seafood to the dose received by humans (46-129 {mu}Sv y{sup -1})

  10. Radiological impact evaluation of an uranium mine in an agricultural soil

    The contamination of a soil near an uranium mine exhaust ventilating shaft was evaluated. The methodology adopted proved to be successful even for facilities which do not present any preoperational or operational results. The activity concentration of 210 Pb, 238U, 226Ra, 228Ra, 137Cs and 40K was measured along a transect of 200m on a field located in the exhaust air direction. The data showed that the activity increased due to the emissions from the mine. The largest effect was observed for 210Pb, whereas smaller effects were observed for 238U and 226Ra. The activity ratios of 210Pb/238U and 238U/226Ra in the soil for distances where the contamination was not detectable anymore, were 1,04 and 1,43 , respectively. These results are in good agreement with other data found in the literature. The semivariograms of the activity concentration of the radionuclides at distances, where the effect of the emissions from the mine was not any longer observable, indicated for 210 Pb and 226Ra the presence of a range (30m and 40m, respectively) within which the variance attains its maximum value. The semivariogram observed for 40K, showed a wider range, indicating the influence of an uneven fertilizers application. A sequential extraction procedure was applied to investigate the speciation of the radionuclides and stable Pb in the soil. The following extractions were carried out: fraction I readily exchangeable, fraction II bound to carbonates and fraction III bound to Fe and Mn oxides. In the soil near the exhaust air the extraction was more effective for 210Pb, 238U and 226Ra . The radionuclide 210Pb was more extracted in fraction I and III, whereas 238U and 226Ra were similarly extracted in fraction II and III. The behaviour of 210Pb was different for the control soil and the agricultural soil. In the control soil 210Pb was more extracted in fraction II and III, whereas in the the agricultural soil it was more extracted in fraction I and III. Stable Pb and 210Pb presented

  11. Vertical distribution of the natural and artificial radionuclides in various soil profiles to investigate soil erosion

    Vertical distributions of 137Cs and 210Pb in soil profiles were examined to study their availability in soil erosion at Goekova region where there exists intensive agricultural activities on sloppy fields. Since the mobility of these radionuclides depend on soil characteristics, soil samples were analyzed also for their physical and chemical properties. From 137Cs inventories measured, erosion rates for cultivated and disturbed (no cultivation) soils were calculated to range from 79.1 to 6.5 t x ha-1 x y-1 and from 79.9 to 3.5 t x ha-1 x y-1, respectively. The 210Pb technique is found to be not suitable for erosion determination for this area, presumably due to the coal-fired power plants operating in the region. (author)

  12. Entwicklung und Validierung einer kombinierten Schnellanalysenmethode zur Bestimmung der natürlichen Radionuklide 210Pb, 210Po, 226Ra, 228Ra, 234U und 238U in Trinkwasser

    Schuster, Martina

    2015-01-01

    Der Richtwert der effektiven Dosis für den Verzehr von Trinkwasser beträgt 0,1 mSv pro Jahr. Zur Berechnung der Dosis müssen die Aktivitätskonzentrationen der relevanten Radionuklide bestimmt werden. Einige Analysenmethoden zur Bestimmung dieser natürlichen Radionuklide sind bekannt, jedoch benötigt man für jedes Nuklid einen komplett anderen und zeitaufwändigen Trennungsgang. In dieser Arbeit wird eine Analysenmethode vorgestellt, mit der die natürlichen Radionuklide 210Pb, 210Po, 226Ra, 228...

  13. Atmospheric deposition of radionuclides (7Be, 210Pb, 134Cs, 137Cs and 40K) during 2000-2012 at Rokkasho, Japan, and impact of the Fukushima Dai-ichi Nuclear Power Plant accident

    We measured the concentrations of several radionuclides in atmospheric deposition samples collected in the period from 2000 to 2012 at Rokkasho, Japan. Monthly 7Be deposition rates were higher in winter/spring and fall, and monthly 210Pb deposition rates were highest in winter/spring. Following the accident at the Fukushima Dai-ichi Nuclear Power Plant in March 2011, the radiocesium (134Cs and 137Cs) deposition rate rapidly increased until it reached the maximum in April 2011, after which the deposition rate of 137Cs decreased with a half-time of 22 days before remaining constant throughout 2012. (author)

  14. Using unsupported lead-210 measurements to investigate soil erosion and sediment delivery in a small Zambian catchment

    Walling, D. E.; Collins, A. L.; Sichingabula, H. M.

    2003-06-01

    Traditional techniques used to assemble information on rates of erosion and soil redistribution possess many important limitations. As a result, the use of environmental radionuclides, and more particularly 137Cs measurements, has attracted increasing attention in recent years as a means of obtaining spatially distributed information on rates of erosion and deposition. The application of the 137Cs approach is, however, hampered in some areas of the world where 137Cs inventories are low and the low concentrations of 137Cs found in soils and sediments cause problems for laboratory analysis. These problems will increase as time progresses due to the radioactive decay of the existing inventory, most of which was deposited as fallout ca. 40 years ago. This contribution explores the potential for using another fallout radionuclide, namely unsupported 210Pb, as an alternative to 137Cs, in the small (63 km 2) Upper Kaleya catchment in southern Zambia where 137Cs inventories are already very low. The approach employed with unsupported 210Pb is similar to that used for 137Cs, although the essentially constant fallout of unsupported 210Pb through time means that the resulting estimates of erosion and soil redistribution rates reflect a longer period of time (ca. 100 years rather than ca. 40 years). The estimates of erosion and deposition rates derived from the unsupported 210Pb measurements are used to construct typical sediment budgets for the three main land-use types in the Upper Kaleya catchment, namely, commercial cultivation, communal cultivation and bush grazing. The results obtained from the unsupported 210Pb are compared with equivalent results based on 137Cs measurements provided by a previous investigation undertaken in the study catchment. The two sets of results are highly consistent. The study reported confirms the viability of using unsupported 210Pb as an alternative to 137Cs in this environment and demonstrates that conjunctive use of both radionuclides can

  15. Evaluation of radiological contamination of a soil cultivation near an uranium mine

    The contamination of a soil near an uranium mine exhaust ventilating shaft was evaluated. The activity concentration of 210 Pb, 238 U, 226 Ra e 228 Ra was measured along a transect of 200 m on a field located in the exhaust air direction. The data showed that the activity increased due to the emissions from the mine. The largest effect was observed for 210 Pb, whereas smaller effects were observed for 238 U and 226 Ra. A sequential extraction procedure was applied to investigate the specification of the radionuclides and stable Pb in the soil. The following extractions were carried out: fraction I readily exchangeable, fraction II bound to carbonates and fraction III bound to Fe and Mn oxides.In the soil near the exhaust air the extraction was more effective for 210 Pb, 238 U and 226 Ra. Concluding 210 Pb was found to be the most critical radionuclide discharged by the exhaust ventilating shaft. Indeed this radionuclide not only presented higher concentration in the near soil but also was the more extracted in fraction I, which is most relevant for the environment. (author)

  16. Use of radionuclide techniques {sup 137}Cs, {sup 210}Pb{sub E}X and Be to assess soil erosion in Moroccan agriculture lands

    Nouira, A.; Benmansour, M.; Benkedad, A.; Bouksirate, H.

    2009-07-01

    Water erosion is one of the major environmental and agricultural problems causing serious socio-economic impairment for not only develop countries but also developing countries. It reduces the fertility and productivity of agricultural lands and it is besides a major source of surface water pollution. On the other hand, intensive or improper farming accelerates greatly this phenomenon. (Author)

  17. Natural and artificial radionuclides in forest and bog soils: tracers for migration processes and soil development

    Radionuclide distributions in undisturbed forest and bog soils, mostly situated in Saxony, Germany (Erzgebirge), were studied. Low concentrations of naturally-occurring U and Th decay series nuclides, including 210Pb, and artificial radioisotopes (125Sb, 134Cs, 137Cs, 241Am) were determined using low-level γ-spectrometry. In addition, the activities of 238Pu and 239,240Pu were determined by radiochemical separation and α-spectrometry. 14C and excess 210Pb dating methods were used to date the sampled bog profiles. The different radionuclides show characteristic depth distributions in the forest and bog soil horizons, which were sub-sampled as thin slices. 125Sb, 241Am, 238Pu and 239,240Pu are strongly fixed in soil organic matter. In spruce forest soils, the influence of soil horizons with distinct properties dominates the vertical time-dependent distribution. In ombrotrophic bogs, the peak positions correlated with the year of maximum input of each nuclide. The Sb, Am and Pu ''time markers'' and the 14C and 210Pb dating results correspond very well. Although Cs seems to be relatively mobile in organic as well as mineral forest soil horizons, it is enriched in the organic material. In ombrotrophic bogs, Cs is very mobile in the peat deposit. In Sphagnum peat, Cs is translocated continuously towards the growing apices of the Sphagnum mosses, where it is accumulated. (orig.)

  18. Determination of the concentration of {sup 238}U, {sup 234}U, {sup 232}Th, {sup 228}Th, {sup 228}Ra, {sup 226}Ra and {sup 210}Pb in the feces of workers from a mining company of niobium and their families; Determinacao da concentracao de {sup 238}U, {sup 234}U, {sup 232}Th, {sup 228}Th, {sup 228}Ra, {sup 226}Ra e {sup 210}Pb na excrecao fecal de trabalhadores de uma mineradora de niobio e de seus familiares

    Oliveira, Roges de; Lopes, Ricardo T. [Coordenacao dos Programas de Pos-Graduacao de Engenharia (LIN/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear. Lab. de Intrumentacao Nuclear; Melo, Dunstana R.; Juliao, Ligia M.Q.C. [Instituto de Radioprotecao e Dosimetria (SEMINIRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Servico de Monitoracao Individual Interna

    2005-07-01

    The object of this study consists of an open mine from which Niobium ore (pyrochlore) is extracted and a metallurgy company, where Fe-Nb alloys are produced for export. For geological reasons, the main ore is associated to natural radionuclides U and Th, and its decay products. The concentration of {sup 234}U, {sup 238}U, {sup 232}Th, {sup 226}Ra and {sup 228}Ra, {sup 228}Th, including {sup 210}Pb in fecal excretion of 12:0 am, 29 workers and 13 family members were determined. The technique employed for the determination of the elements was the sequential method of radiochemical separation, followed by alpha spectrometry and counting {alpha} and {beta} in proportional detector. Statistically significant difference was observed in the concentration of {sup 234}U and {sup 238}U, in feces samples, among the group of mining workers and family members; as well as for {sup 232}Th in the feces of workers of crushing and metallurgy groups when compared with the Family Group. No statistically significant difference was detected at a concentration of {sup 226}Ra, {sup 228}Ra and {sup 210}Pb, in feces of any group of workers of the installation in relation to the family group.

  19. Quality assurance exercise for estimating low-levels of beta emitter (90Sr) in spiked soil matrix: results of an inter-laboratory studies

    The results of two inter-laboratory proficiency tests (first ALMERA and MAPEP-98-W6) are summarized. Inter-laboratory studies are performed with different aims and consequently require different evaluation methods and statistical treatment. As a part of quality assurance (proficiency testing), EAD, BARC participated in the first ALMERA proficiency test organized by International Atomic Energy Agency (IAEA) on the determination of α- and β - emitting radionuclides in soil matrix and solution and MAPEP organized by United State Department of Energy (USDOE) on the determination of 90Sr in 5% nitric acid solution. The results submitted by the laboratory were found to be in very good agreement with IAEA's and USDOE's target (spiked) values. (author)

  20. Dating of a sediment core from Lake Biel (Switzerland) and source characterization of fallout Pu; {sup 210}Pb- und {sup 137}Cs-Datierung eines Sedimentbohrkerns aus dem Bieler See (CH) und Ursprungsbestimmung von Pu-Fallout

    Pregler, Anja

    2016-08-01

    A sediment core from Lake Biel was dated by means of the naturally occurring radioactive isotope {sup 210}Pb as well as by the anthropogenic isotope {sup 137}Cs. The latter one can be detected as radioactive fallout of certain events in the sediment layers and accordingly be correlated with a distinct date. A verification of the correlated events is accomplished by particular isotope ratios of the anthropogenic isotopes {sup 238}Pu, {sup 239}Pu and {sup 240}Pu as well as {sup 241}Am as a decay product of the short-lived {sup 241}Pu. Furthermore, the percentage of the total {sup 137}Cs fallout was calculated corresponding to the specific events.

  1. Modern Sedimentation Rates of Fuxian Lake by 210pb and 137Cs Dating%云南抚仙湖近现代沉积速率变化研究

    王小雷; 杨浩; 丁兆运; 杨本俊; 张明礼

    2011-01-01

    借助GPS定位,采集了云南抚仙湖不同区域的7个沉积物柱芯.通过对抚仙湖沉积物柱芯样品的放射性核素210Pb和137Cs测试分析,发现所有柱芯中均存在3个公认的137Cs计年时标(1954年137Cs首次沉降、1963年全球公认的137Cs最大沉降蓄积峰和l986年前苏联切尔诺贝利核事故产生的137Cs沉降蓄积峰),部分柱芯中存在20世纪70年代中期中国大气核试验形成的1975/1976年次级蓄积峰,分析了该次级定年时标存在的合理性.借助210Pb CRS计年模式获得了抚仙湖过去百余年来的沉积年代,与137Cs时标计年结果相比较存在一定偏差,对两种计年结果产生差异的可能原因进行了探讨.基于210pb和137Cs计年结果,结合历史文献记载得出,自19世纪中期以来,抚仙湖各个沉积物柱芯(FX6除外)的沉积速率变化规律具有相似性,大致可以划分为3个阶段:A:自然演化阶段,B:人为扰动阶段,C:人为改造阶段.这种不稳定的沉积环境与抚仙湖地区相应历史时期的人类活动有密切关系,表明人类活动是影响短时间尺度下环境变化的主要驱动力.%Based on GPS location, seven sediment cores were collected from different areas of Fuxian Lake. By analyzing the radionuclide profiles of 210Pb and 137Cs, we found that there were three obvious time markers of l37Cs in all the sediment cores, which corresponded to the onset of fallout in 1954, the maximum peak fallout in 1963 and the former Soviet Union's Chernobyl accident in 1986. Some sediment cores (FX1, FX3, FX5 and FX7) had the secondary peaks in 1975 or 1976 by the Chinese nuclear tests, verifying the rationality of this auxiliary time marker. On the basis of the 210Pb (CRS) dating, the ages were obtained in the past 150 years. As for dissimilar physical and chemical associations, diffusion characteristics for the two radionuclides (Pb and Cs), we interpreted the rationality of deviation by the two dating methods. In

  2. Degradation of γ-HCH spiked soil using stabilized Pd/Fe0 bimetallic nanoparticles: Pathways, kinetics and effect of reaction conditions

    Highlights: ► This study explores the potential of CMC-Pd/nFe0 to degrade γ-HCH in spiked soil. ► Sorption–desorption characteristics and partitioning of γ-HCH is investigated. ► Three degradation pathways has been proposed and discussed. ► γ-HCH degradation mechanism and kinetics is elucidated. ► Activation energy reveals that γ-HCH degradation is a surface mediated reaction. - Abstract: This study investigates the degradation pathway of gamma-hexachlorocyclohexane (γ-HCH) in spiked soil using carboxymethyl cellulose stabilized Pd/Fe0 bimetallic nanoparticles (CMC-Pd/nFe0). GC–MS analysis of γ-HCH degradation products showed the formation of pentachlorocyclohexene, tri- and di-chlorobenzene as intermediate products while benzene was formed as the most stable end product. On the basis of identified intermediates and final products, degradation pathway of γ-HCH has been proposed. Batch studies showed complete γ-HCH degradation at a loading of 0.20 g/L CMC-Pd/nFe0 within 6 h of incubation. The surface area normalized rate constant (kSA) was found to be 7.6 × 10−2 L min−1 m−2. CMC-Pd/nFe0 displayed ∼7-fold greater efficiency for γ-HCH degradation in comparison to Fe0 nanoparticles (nFe0), synthesized without CMC and Pd. Further studies showed that increase in CMC-Pd/nFe0 loading and reaction temperature facilitates γ-HCH degradation, whereas a declining trend in degradation was noticed with the increase in pH, initial γ-HCH concentration and in the presence of cations. The data on activation energy (33.7 kJ/mol) suggests that γ-HCH degradation is a surface mediated reaction. The significance of the study with respect to remediation of γ-HCH contaminated soil using CMC-Pd/nFe0 has been discussed.

  3. Degradation of {gamma}-HCH spiked soil using stabilized Pd/Fe{sup 0} bimetallic nanoparticles: Pathways, kinetics and effect of reaction conditions

    Singh, Ritu [Ecotoxicology Division, CSIR-Indian Institute of Toxicology Research, Post Box 80, Mahatma Gandhi Marg, Lucknow 226 001, UP (India); Department of Environmental Science, Babasaheb Bhimrao Ambedkar University, Raebareli Road, Lucknow 226 025, UP (India); Misra, Virendra, E-mail: virendra_misra2001@yahoo.co.in [Ecotoxicology Division, CSIR-Indian Institute of Toxicology Research, Post Box 80, Mahatma Gandhi Marg, Lucknow 226 001, UP (India); Mudiam, Mohana Krishna Reddy [Analytical Chemistry Division, CSIR-Indian Institute of Toxicology Research, Post Box 80, Mahatma Gandhi Marg, Lucknow 226 001, UP (India); Chauhan, Lalit Kumar Singh [Petroleum Toxicology Division, CSIR-Indian Institute of Toxicology Research, Post Box 80, Mahatma Gandhi Marg, Lucknow 226 001, UP (India); Singh, Rana Pratap [Department of Environmental Science, Babasaheb Bhimrao Ambedkar University, Raebareli Road, Lucknow 226 025, UP (India)

    2012-10-30

    Highlights: Black-Right-Pointing-Pointer This study explores the potential of CMC-Pd/nFe{sup 0} to degrade {gamma}-HCH in spiked soil. Black-Right-Pointing-Pointer Sorption-desorption characteristics and partitioning of {gamma}-HCH is investigated. Black-Right-Pointing-Pointer Three degradation pathways has been proposed and discussed. Black-Right-Pointing-Pointer {gamma}-HCH degradation mechanism and kinetics is elucidated. Black-Right-Pointing-Pointer Activation energy reveals that {gamma}-HCH degradation is a surface mediated reaction. - Abstract: This study investigates the degradation pathway of gamma-hexachlorocyclohexane ({gamma}-HCH) in spiked soil using carboxymethyl cellulose stabilized Pd/Fe{sup 0} bimetallic nanoparticles (CMC-Pd/nFe{sup 0}). GC-MS analysis of {gamma}-HCH degradation products showed the formation of pentachlorocyclohexene, tri- and di-chlorobenzene as intermediate products while benzene was formed as the most stable end product. On the basis of identified intermediates and final products, degradation pathway of {gamma}-HCH has been proposed. Batch studies showed complete {gamma}-HCH degradation at a loading of 0.20 g/L CMC-Pd/nFe{sup 0} within 6 h of incubation. The surface area normalized rate constant (k{sub SA}) was found to be 7.6 Multiplication-Sign 10{sup -2} L min{sup -1} m{sup -2}. CMC-Pd/nFe{sup 0} displayed {approx}7-fold greater efficiency for {gamma}-HCH degradation in comparison to Fe{sup 0} nanoparticles (nFe{sup 0}), synthesized without CMC and Pd. Further studies showed that increase in CMC-Pd/nFe{sup 0} loading and reaction temperature facilitates {gamma}-HCH degradation, whereas a declining trend in degradation was noticed with the increase in pH, initial {gamma}-HCH concentration and in the presence of cations. The data on activation energy (33.7 kJ/mol) suggests that {gamma}-HCH degradation is a surface mediated reaction. The significance of the study with respect to remediation of {gamma}-HCH contaminated soil using

  4. Determination of distribution coefficients of some natural radionuclides (U, Ra, Pb, Po) between different types of Syrian soils and their solutions

    In this study, distribution coefficients of some natural radionuclides (226Ra, U, 210Pb and 210Po) between different types of soils in Syria and their solutions were determined. The distribution coefficients values ranged from (164-1933, 280-1722, 350-4749 and 101-117) l kg-1 for 226Ra, U, 210Pb and 210Po, respectively at pH = 4.0. While, the distribution coefficients values ranged from (207-6706, 673-2397, 149-2147 and 103- 292) l kg-1 for 226Ra, U, 210Pb and 210Po, respectively at pH = 5.5. In addition, the distribution coefficients values ranged from (167-1707, 126- 1239, 44-1122 and 125-1475) l kg-1 for 226Ra, U, 210Pb and 210Po, respectively at pH = 7.0. Moreover, the results showed that 210Po distribution coefficients had the maximum values at pH 7. While 210Pb distribution coefficients had the minimum values at same pH. In addition to, U distribution coefficients had the maximum values at pH 5.5. On the other hand, the effect of soil mineral content, CEC, ECE, pH and soluble ions on the distribution coefficients were investigated. In general, the results showed that there are logarithmic relationships between studied radionuclide activity in the soil and their distribution coefficients in all soil types (R2 ranged from 0.59 to 1.00 at pH 4.0). On the other hand, there were no relationships between the distribution coefficients and soil pH. (authors)

  5. Geochemistry of natural radionuclide in soils surrounding a mining and plant uranium concentration;Geoquimica de radionuclindeos naturais em solos de areas circunvizinhas a uma unidade de mineracao e atividade de uranio

    Cardoso, Gildevan Viana, E-mail: gildevan.cardoso@vta.incra.gov.b [Instituto Nacional de Colonizacao e Reforma Agraria (INCRA), Rio de Janeiro, RJ (Brazil); Amaral Sobrinho, Nelson Moura Brasil do; Mazur, Nelson, E-mail: nelmoura@ufrrj.b, E-mail: nelmazur@ufrrj.b [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Inst. de Agronomia. Dept. de Solos; Wasserman, Maria Angelica Vergara, E-mail: angelica@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2009-11-15

    The environmental impacts resulting from uranium exploration and processing are to a great extent identical to those caused by extractive mining activities in general. This study aimed to determine the geochemical partitioning of the natural radionuclides {sup 238}U, {sup 226}Ra and {sup 210}Pb in areas surrounding the Uranium Mining and Concentration Plant (URA) of the Brazilian Nuclear Industries S.A., in the uranium deposit region of Lagoa Real, in Caetite, southwestern Bahia state. Representative soil samples of the main regional soil classes were collected from the layer 0-20 cm, in five areas around the URA. The level of total activity and geochemical fractionation (F1 slightly acidic, F2 reducible, F3 oxidisable, F4 alkaline, and F5 residual) were determined for the five areas. The average total radioactivity levels were, in Bq kg{sup -1} soil: 50 for {sup 238}U, 51 for {sup 226}Ra, and 159 for {sup 210}Pb. During the potentially bioavailable phase (F1) 11 % were extracted for {sup 238}U, 13 % for {sup 226}Ra and 3 % for {sup 210}Pb. The bioavailability of {sup 238}U was higher in more acidic soils and the affinity for iron oxides was greater, unlike in the case of {sup 226}Ra, with the greatest bioavailability. {sup 210}Pb was predominantly associated with F5. The high percentage of {sup 238}U, {sup 226}Ra and {sup 210}Pb in the geochemical fraction F5 indicates that the concentrations observed in the five soils are predominantly associated to the parent material of these soils, rather than to an artificial contamination caused by the URA activity. (author)

  6. Use of fallout radionuclides ((7)Be, (210)Pb) to estimate resuspension of Escherichia coli from streambed sediments during floods in a tropical montane catchment.

    Ribolzi, Olivier; Evrard, Olivier; Huon, Sylvain; Rochelle-Newall, Emma; Henri-des-Tureaux, Thierry; Silvera, Norbert; Thammahacksac, Chanthamousone; Sengtaheuanghoung, Oloth

    2016-02-01

    Consumption of water polluted by faecal contaminants is responsible for 2 million deaths annually, most of which occur in developing countries without adequate sanitation. In tropical aquatic systems, streambeds can be reservoirs of persistent pathogenic bacteria and high rainfall can lead to contaminated soils entering streams and to the resuspension of sediment-bound microbes in the streambed. Here, we present a novel method using fallout radionuclides ((7)Be and (210)Pbxs) to estimate the proportions of Escherichia coli, an indicator of faecal contamination, associated with recently eroded soil particles and with the resuspension of streambed sediments. We show that using these radionuclides and hydrograph separations we are able to characterize the proportion of particles originating from highly contaminated soils and that from the resuspension of particle-attached bacteria within the streambed. We also found that although overland flow represented just over one tenth of the total flood volume, it was responsible for more than two thirds of the downstream transfer of E. coli. We propose that data obtained using this method can be used to understand the dynamics of faecal indicator bacteria (FIB) in streams thereby providing information for adapted management plans that reduce the health risks to local populations. Graphical Abstract Graphical abstract showing (1) the main water flow processes (i.e. overland flow, groundwater return flow, blue arrows) and sediment flow components (i.e. resuspension and soil erosion, black arrows) during floods in the Houay Pano catchment; (2) the general principle of the method using fallout radionuclide markers (i.e. (7)Be and (210)Pbxs) to estimate E. coli load from the two main sources (i.e. streambed resuspension vs soil surface washoff); and 3) the main results obtained during the 15 May 2012 storm event (i.e. relative percentage contribution of each process to the total streamflow, values in parentheses). PMID:26490918

  7. Improvement of a method for the sequential determination of {sup 210}Pb, {sup 226}Ra, and uranium isotopes by LSC and alpha-particle spectrometry

    Lozano, J.C. [Departamento de Fisica Fundamental, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca (Spain); Blanco Rodriguez, P. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain); Vera Tome, F., E-mail: fvt@unex.es [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain); Leal-Cidoncha, E. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, 06071 Badajoz (Spain)

    2012-04-15

    In a previous paper the authors proposed a sequential method for the determination of isotopes of uranium, thorium, radium, and lead from environmental samples using alpha-particle spectrometry and LSC techniques. Although the radiochemical yields were suitable when the assays were performed on synthetic samples, application to real environmental samples caused a major decrease in the radiochemical yield, especially for uranium in inorganic samples (soils). A modification of the procedure is described that overcomes this drawback. - Highlights: Black-Right-Pointing-Pointer Sequential methods permit one to obtain the radionuclides from the same aliquot. Black-Right-Pointing-Pointer The proposal method enhances the radiochemical yields. Black-Right-Pointing-Pointer For soil samples, the yields were of (56{+-}2)%, (57{+-}6)%, and (71{+-}4)% for U, Ra, and Pb.

  8. The electromagnetic spike solutions

    Nungesser, Ernesto; Lim, Woei Chet

    2013-12-01

    The aim of this paper is to use the existing relation between polarized electromagnetic Gowdy spacetimes and vacuum Gowdy spacetimes to find explicit solutions for electromagnetic spikes by a procedure which has been developed by one of the authors for gravitational spikes. We present new inhomogeneous solutions which we call the EME and MEM electromagnetic spike solutions.

  9. Removal of radionuclides of the uranium-radium series from polluted soil by wheat plants

    To study the problem of the removal of radionuclides of uranium-radium series (226Ra, 230Th, 210Pb and U) with wheat crops out of contaminated soils, connections between amounts of nuclides in soil and in straw are studied. It is shown that the rate of soil self-purification of radionuclides of uranium-radium series at the expense of their removal by the crop is lower than at the expence of migration into below-lying horizons of soil. Ca content in soil reduces radionuclide transfer from soil to plants

  10. Investigation of the soil-plant transfer of primordial radionuclides in tomatoes by low-level γ-ray spectrometry

    The paper presents actual data from investigations of the soil-plant transfer of the primordial radionuclides 40K, 238U, 226Ra, 210Pb and 227Ac for tomatoes growing at soils from former uranium mining areas. The analysis were carried out using low-level γ-ray spectrometry in a 47 m deep underground laboratory. For tomato fruits transfer factors of (0.0007±0.0006) for 238U, (0.0021±0.0017) for 226Ra, (0.0015±0.0009) for 210Pb and (0.0018±0.0012) for 227Ac were obtained. The investigation of the soil-plant transfer by low-level γ-ray spectrometry is often limited by the Compton-continuum from the always present high-energy γ-ray emitter 40K

  11. Monitoring spike train synchrony

    Kreuz, Thomas; Houghton, Conor; Andrzejak, Ralph G; Mormann, Florian

    2012-01-01

    Recently, the SPIKE-distance has been proposed as a parameter-free and time-scale independent measure of spike train synchrony. This measure is time-resolved since it relies on instantaneous estimates of spike train dissimilarity. However, its original definition led to spuriously high instantaneous values for event-like firing patterns. Here we present a substantial improvement of this measure which eliminates this shortcoming. The reliability gained allows us to track changes in instantaneous clustering, i.e., time-localized patterns of (dis)similarity among multiple spike trains. Additional new features include selective and triggered temporal averaging as well as the instantaneous comparison of spike train groups. In a second step, a causal SPIKE-distance is defined such that the instantaneous values of dissimilarity rely on past information only so that time-resolved spike train synchrony can be estimated in real-time. We demonstrate that these methods are capable of extracting valuable information from ...

  12. Radioactivity in soils and some terrestrial foodstuffs from organic and conventional farming areas in Izmir, Turkey

    The activity concentrations of the naturally occurring radionuclides of 210Po, 210Pb, 226Ra, 228Ra and 40K were determined in wheat, grape leaf, garlic, onion and soil samples collected from organic and conventional farms in the Izmir region. In addition, soil-to-plant transfer factors were estimated. While the activity concentrations of 210Po and 210Pb were determined by alpha spectrometry, those of 226Ra, 228Ra and 40K, were determined by gamma spectrometry. The samples collected from conventional farms showed higher activity concentrations of the above radionuclides when compared to those collected from organic farms. In general, the transfer factor values fall within the range given in the literature. (author)

  13. Western Tasmania - A reconstructed history of wide-spread aerial pollution in a formerly 'pristine' area - the use of 210Pb and 22Ra in retrospective monitoring of the environment

    Full text: Using nuclear dating techniques and trace metal analysis of sediment cores an environmental history of Western Tasmania was reconstructed. Seven sites were selected to encompass a range of environments from highly human impacted to relatively pristine. They include sub-alpine tarns and coastal lowland lakes. Disturbed areas have been impacted by activities associated with logging, mining and colonial settlement while the near-pristine sites were located in areas with little disturbance, such as the Tasmanian Wilderness World Heritage Area. Lead-210 (210Pb) and radium-226 (226Ra), both naturally occurring radioisotopes, were used to determine sediment accumulation rates and establish chronologies. Sediment cores collected from near pristine lakes were expected to reveal low and relatively constant trace metal concentrations consistent with areas subject to little to no human impact. However, evidence from these sediment cores revealed trace metal concentrations peaked in the 1960s and then began to decrease in the 1980s. This trend was also discovered, to a greater extent, in sediment cores collected from human impacted sites particularly those surrounding the Central Western mining area. Of all the metals investigated, lead (Pb), arsenic (As), tin (Sn) and copper (Cu) were found to show the most marked increases. Temporal increases in metal concentrations were found to be a result of mining activities in Central Western Tasmania. Evidence for the most significant increase as shown by the trace metal profile coincided with the escalation of open cut mining while decreases in metal concentrations around 1980 coincided with the cessation of mining. Spatially, the dispersal was predominantly due to aerial pollution as concentrations of Pb, As, Sn and Cu were highest close to the mining areas although sites as far as 150 kilometres away showed marked metal concentration increases above background levels around 1960. (author)

  14. Geoquímica de radionuclídeos naturais em solos de áreas circunvizinhas a uma Unidade de Mineração e Atividade de Urânio Geochemistry of natural radionuclide in soils surrounding a Mining and Plant Uranium Concentration

    Gildevan Viana Cardoso

    2009-12-01

    of the Brazilian Nuclear Industries S.A., in the uranium deposit region of Lagoa Real, in Caetité, southwestern Bahia state. Representative soil samples of the main regional soil classes were collected from the layer 0-20 cm, in five areas around the URA. The level of total activity and geochemical fractionation (F1slightly acidic, F2 reducible, F3 oxidisable, F4 alkaline, and F5 residual were determined for the five areas. The average total radioactivity levels were, in Bq kg-1 soil: 50 for 238U, 51 for 226Ra, and 159 for 210Pb. During the potentially bioavailable phase (F1 11 % were extracted for 238U, 13 % for 226Ra and 3 % for 210Pb. The bioavailability of 238U was higher in more acidic soils and the affinity for iron oxides was greater, unlike in the case of 226Ra, with the greatest bioavailability. 210Pb was predominantly associated with F5. The high percentage of 238U, 226Ra and 210Pb in the geochemical fraction F5 indicates that the concentrations observed in the five soils are predominantly associated to the parent material of these soils, rather than to an artificial contamination caused by the URA activity.

  15. Measuring spike train synchrony

    Kreuz, T; Haas, J S; Morelli, A; Politi, A; Abarbanel, Henry D. I.; Haas, Julie S.; Kreuz, Thomas; Morelli, Alice; Politi, Antonio

    2007-01-01

    Estimating the degree of synchrony or reliability between two or more spike trains is a frequent task in both experimental and computational neuroscience. In recent years, many different methods have been proposed that typically compare the timing of spikes on a certain time scale to be fixed beforehand. Here, we propose the ISI-distance, a simple complementary approach that extracts information from the interspike intervals by evaluating the ratio of the instantaneous frequencies. The method is parameter free, time scale independent and easy to visualize as illustrated by an application to real neuronal spike trains obtained in vitro from rat slices. In a comparison with existing approaches on spike trains extracted from a simulated Hindemarsh-Rose network, the ISI-distance performs as well as the best time-scale-optimized measure based on spike timing.

  16. Dynamical laser spike processing

    Shastri, Bhavin J; Tait, Alexander N; Rodriguez, Alejandro W; Wu, Ben; Prucnal, Paul R

    2015-01-01

    Novel materials and devices in photonics have the potential to revolutionize optical information processing, beyond conventional binary-logic approaches. Laser systems offer a rich repertoire of useful dynamical behaviors, including the excitable dynamics also found in the time-resolved "spiking" of neurons. Spiking reconciles the expressiveness and efficiency of analog processing with the robustness and scalability of digital processing. We demonstrate that graphene-coupled laser systems offer a unified low-level spike optical processing paradigm that goes well beyond previously studied laser dynamics. We show that this platform can simultaneously exhibit logic-level restoration, cascadability and input-output isolation---fundamental challenges in optical information processing. We also implement low-level spike-processing tasks that are critical for higher level processing: temporal pattern detection and stable recurrent memory. We study these properties in the context of a fiber laser system, but the addit...

  17. Temporal spike pattern learning.

    Talathi, Sachin S; Abarbanel, Henry D I; Ditto, William L

    2008-09-01

    Sensory systems pass information about an animal's environment to higher nervous system units through sequences of action potentials. When these action potentials have essentially equivalent wave forms, all information is contained in the interspike intervals (ISIs) of the spike sequence. How do neural circuits recognize and read these ISI sequences? We address this issue of temporal sequence learning by a neuronal system utilizing spike timing dependent plasticity (STDP). We present a general architecture of neural circuitry that can perform the task of ISI recognition. The essential ingredients of this neural circuit, which we refer to as "interspike interval recognition unit" (IRU) are (i) a spike selection unit, the function of which is to selectively distribute input spikes to downstream IRU circuitry; (ii) a time-delay unit that can be tuned by STDP; and (iii) a detection unit, which is the output of the IRU and a spike from which indicates successful ISI recognition by the IRU. We present two distinct configurations for the time-delay circuit within the IRU using excitatory and inhibitory synapses, respectively, to produce a delayed output spike at time t_{0}+tau(R) in response to the input spike received at time t_{0} . R is the tunable parameter of the time-delay circuit that controls the timing of the delayed output spike. We discuss the forms of STDP rules for excitatory and inhibitory synapses, respectively, that allow for modulation of R for the IRU to perform its task of ISI recognition. We then present two specific implementations for the IRU circuitry, derived from the general architecture that can both learn the ISIs of a training sequence and then recognize the same ISI sequence when it is presented on subsequent occasions. PMID:18851076

  18. An investigation of the speciation of radionuclides in sediments and soils

    A sequential chemical extraction procedure has been used to investigate the speciation of the radionuclides 210Pb and 226Ra in three soil and sediment samples from the Mt. Brockman area in the Northern Territory. The analyses, by γ-ray spectrometry, are in terms of those species that are exchangeable, bound to carbonates, bound to iron or manganese oxides, bound to organic matter, and tightly bound in the crystal lattices of various minerals. The results for the radionuclides indicate significant differences between 210Pb and 226Ra in their distribution among the fractions, with very little 226Ra present in all residual fractions. Very low concentrations of both radionuclides were present in the fractions representing species bound to carbonates, with 226 Ra concentrations greater that 210Pb. Where the iron content of the sample is high, and in the form of iron oxides, both radionuclides are associated largely with the iron oxide phase. The fraction representing species bound to organic matter contained relatively high concentrations of both radionuclides in all samples

  19. Intercomparison exercise for the estimation of low levels of man made gamma emitters in soil sample

    The Low Level Counting Laboratory of Egad, BARC participated in the Proficiency Test organized by the International Atomic Energy Agency (IAEA). Intercomparison exercise is the mean for quality assurance and quality control of the system hence to provide good quality analytical result for important decision making. This paper discusses the data evaluation of the analysis result for estimating the low levels of man made gamma emitters in soil sample. 54Mn, 60Co, 65Zn, 137Cs, 210Pb, 241Am were analysed in the sample by using p-type HPGe coupled gamma spectrometry system. The analysis result of 241Am was not matching with IAEA value and 210Pb was not reported. This is attributed to the fact that the low energy photons (∼60 keV) are getting attenuated in coaxial p-type HPGe detector because of the large thickness (∼600m) of the outer contact. Except 210Pb and 241Am, the analysis result of this laboratory passed in the evaluation criteria stipulated by IAEA. (author)

  20. Spike, sex and subtext

    Williamson, Milly

    2005-01-01

    Abstract The vampire Spike of Buffy the Vampire Slayer is the latest in a long line of a mbiguous but sympathetic vampires which have caught the public imagination, stretching back to Polidori?s Byronesque vampire, Lord Ruthven. This article argues that the vampire image that circulates across contemporary vampire fan cultures is one that exceeds any individual depiction of the vampire; the ...

  1. Analysis of PBDEs in soil, dust, spiked lake water, and human serum samples by hollow fiber-liquid phase microextraction combined with GC-ICP-MS.

    Xiao, Qin; Hu, Bin; Duan, Jiankun; He, Man; Zu, Wanqing

    2007-10-01

    A novel method for the analysis of four polybrominated diphenyl ethers (PBDEs) in environmental and human serum samples based on hollow fiber-liquid phase microextraction (HF-LPME) followed by gas chromatography-inductively coupled plasma mass spectrometric (GC-ICP-MS) detection has been developed. The organic solvent in the porous hollow fiber was first dipped into the sample for extraction at a given time, and the retracted organic phase was introduced into the GC-ICP-MS for analysis. The addition of methanol has a strong effect on the HF-LPME extraction efficiency. Other significant parameters affecting the extraction efficiency of HF-LPME were also studied. HF-LPME was effective to isolate the analytes from the complex matrix. Under the optimized conditions, the detection limits of the proposed method varied from 15.2 to 40.5 ng/L. In general, the relative standard deviations (RSDs) were less than 10%. Good linearity was obtained with the correlation coefficients all better than 0.999. The proposed method is simple, quick, few microliters of organic solvent required, and is especially suitable for the analysis of the real sample with small amount available. The overall process of HF-LPME with GC-ICP-MS was applied successfully for the determination of polybrominated diphenyl ethers (PBDEs) in environmental and spiked human serum samples, and the results were satisfactory. PMID:17702599

  2. Effects of industrial by-product amendments on As, Cd and Tl retention/release in an element-spiked acidic soil

    To asses the efficiency of two by-products (phosphogypsum (PG) and sugar foam (SF), rich in gypsum and calcium carbonate, respectively) in the immobilization of three toxic elements (As, Cd and Tl) in an acidic soil, batch-scale sorption and desorption experiments were conducted after 18 months of in situ amendment application. The Langmuir isotherms applied for sorption studies showed that the estimated maximum sorption capacity of the elements was highest in the SF-treated samples. The amount of element retained and the percentage of extraction after TCLP tests indicated that those samples amended with sugar foam (SF and PG + SF) had the potential to immobilize As, Cd and Tl in an acidic soil with low sorptive capacity. In addition to sorption and desorption experiments, scanning electron microscopy in back-scattered electron mode (SEM-BSE) showed the formation of Al-hydroxy polymers which provides the soil with additional sorption capacity. The three target elements were associated with the Al-hydroxy polymers, probably through direct coordination or the formation of ternary complexes. By means of statistical analysis it has been found that sorption processes of As, Cd and Tl in this soil mainly depend on the treatment, whereas desorption is an element-dependent process

  3. Activity and population dynamics of heterotrophic and ammonia-oxidizing microorganisms in soil surrounding sludge bands spiked with linear alkylbenzene sulfonate

    Brandt, K. K.; Sørensen, J.; Krogh, P. H.

    2003-01-01

    bioluminescence toxicity assay, however, LAS or other sludge components never accumulated to toxic levels in the soil compartments and the LAS tolerance of the indigenous microbes further remained unchanged following LAS exposure. LAS effects on the investigated microbial populations largely occurred during...

  4. A comprehensive review on soil erosion using 7Be measurement

    7Be is a natural cosmogenic radionuclide with a relative short half-life of 53.3 d. It is mainly produced in the upper atmosphere as the product of the spallation of oxygen and nitrogen nuclei by cosmic rays. Through continuously wet and dry deposition, 7Be is absorbed strongly by soil particle once it deposits onto the earth's surface. Therefore, it has been regarded as a valuable tracer to document short-term and individual-event soil erosion in recent years. Moreover, it also can be combined with other radionuclides (such as 137Cs, 210Pb, 226Ra) to study soil erosion process. This paper reviewed the previous researches results, including the principle of using 7Be measurement to document soil erosion and the conversion models of soil erosion rates from 7Be data. The problems, suggestions and prospects for further application of 7Be measurement were also discussed. (authors)

  5. Radioxenon spiked air.

    Watrous, Matthew G; Delmore, James E; Hague, Robert K; Houghton, Tracy P; Jenson, Douglas D; Mann, Nick R

    2015-12-01

    Four of the radioactive xenon isotopes ((131m)Xe, (133m)Xe, (133)Xe and (135)Xe) with half-lives ranging from 9 h to 12 days are produced from nuclear fission and can be detected from days to weeks following their production and release. Being inert gases, they are readily transported through the atmosphere. Sources for release of radioactive xenon isotopes include operating nuclear reactors via leaks in fuel rods, medical isotope production facilities, and nuclear weapons' detonations. They are not normally released from fuel reprocessing due to the short half-lives. The Comprehensive Nuclear-Test-Ban Treaty has led to creation of the International Monitoring System. The International Monitoring System, when fully implemented, will consist of one component with 40 stations monitoring radioactive xenon around the globe. Monitoring these radioactive xenon isotopes is important to the Comprehensive Nuclear-Test-Ban Treaty in determining whether a seismically detected event is or is not a nuclear detonation. A variety of radioactive xenon quality control check standards, quantitatively spiked into various gas matrices, could be used to demonstrate that these stations are operating on the same basis in order to bolster defensibility of data across the International Monitoring System. This paper focuses on Idaho National Laboratory's capability to produce three of the xenon isotopes in pure form and the use of the four xenon isotopes in various combinations to produce radioactive xenon spiked air samples that could be subsequently distributed to participating facilities. PMID:26318775

  6. Use of nuclear techniques in soil erosion and siltation studies IAEA activities

    Soil erosion and deposition represent a serious threat in many countries because of their impact on sustainable agricultural development and environmental conservation. Environmental radioactivity (137Cs, 239Pu, 240Pu, 210Pb, 7Be, 14C, 32Si, 26Al, 36Cl) can be used to assess soil erosion, deposition patterns in water bodies and other related problems, depending on the time-scale involved. Caesium-137 and 210Pb were by far the most commonly used radioisotopes for erosion and siltation studies, but further developments are needed to promote broader application of these techniques. To review the state of the art of the use of environmental radioisotopes in soil erosion and siltation studies, an Advisory Group Meeting (AGM) was held at the IAEA's Headquarters in April 1993. Specialists in environmental radioactivity, and representatives of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture and the Land and Water Development Division of the Food and Agriculture Organization of the United Nations attended the meeting. The presentations and discussions held at this AGM showed that fallout radionuclide together with 7Be and 210Pb, are important tools for erosion studies, especially when they combined with conventional methods. In many cases, they allow determination of sedimentation rates in lakes, estuaries and man made reservoirs and provide extensive information on the dynamics and origin of deposited sediments. The most important conclusions and recommendations for future work that arose from this AGM are included here. A Co-ordinated Research Programme (CRP) on this subject is planned for 1995. Detailed information on the CRP objectives and proposed methodologies is presented. (author). 25 refs

  7. Leach tests on grouts made with actual and trace metal-spiked synthetic phosphate/sulfate waste

    Pacific Northwest Laboratory conducted experiments to produce empirical leach rate data for phosphate-sulfate waste (PSW) grout. Effective diffusivities were measured for various radionuclides (90Sr, 99Tc, 14C, 129I, 137Cs, 60Co, 54Mn, and U), stable major components (NO3-, SO42-, H3BO3, K and Na) and the trace constituents Ag, As, Cd, Hg, Pb, and Se. Two types of leach tests were used on samples of actual PSW grout and synthetic PSW grout: the American Nuclear Society (ANS) 16.1 intermittent replacement leach test and a static leach test. Grout produced from both synthetic and real PSW showed low leach rates for the trace metal constituents and most of the waste radionuclides. Many of the spiked trace metals and radionuclides were not detected in any leachates. None of the effluents contained measurable quantities of 137Cs, 60Co, 54Mn, 109Cd, 51Cr, 210Pb, 203Hg, or As. For those trace species with detectable leach rates, 125I appeared to have the greatest leach rate, followed by 99Tc, 75Se, and finally U, 14C, and 110mAg. Leach rates for nitrate are between those for I and Tc, but there is much scatter in the nitrate data because of the very low nitrate inventory. 32 refs., 6 figs., 15 tabs

  8. Coronavirus spike-receptor interactions

    Mou, H.

    2015-01-01

    Coronaviruses cause important diseases in humans and animals. Coronavirus infection starts with the virus binding with its spike proteins to molecules present on the surface of host cells that act as receptors. This spike-receptor interaction is highly specific and determines the virus’ cell, tissue

  9. Radioactivity measurements in soils surrounding four coal-fired power plants in Serbia by gamma-ray spectrometry and estimated dose

    Vukašinović Ivana Ž.

    2014-01-01

    Full Text Available The study of spatial distribution of activity concentration of 238U, 226Ra, 210Pb, 232Th, 40K, and 137Cs radionuclides in the surface soil samples (n = 42 collected in the vicinity of four coal-fired power plants in Serbia is presented. Radioactivity measurements in soils performed by gamma-ray spectrometry showed values [Bqkg-1] in the range: 15-117 for 238U, 21-115 for 226Ra, 33-65 for 210Pb, 20-69 for 232Th, 324-736 for 40K, and 2-59 for 137Cs. Surface soil radio-activity that could have resulted from deposition of radionuclides from airborne discharges or resuspension of ash from disposal sites showed no enhanced levels. It was found that variation of soil textural properties, pH values, and carbonate content influenced activity levels of natural radionuclides while radiocesium activities were associated with soil organic matter content. Modification of some soil properties was observed in the immediate vicinity (<1 km of power plants where the soil was more alkaline with coarser particles (0.2-0.05 mm and carbonates accumulated. Calculated average values of the absorbed gamma dose rate and annual external effective dose originating from the terrestrial radionuclides were 69.4 nGy/h and 0.085 mSv, respectively. [Projekat Ministarstva nauke Republike Srbije, br. 4007: Studying climate change and its influence on the environment: impacts, adaptation and mitigation

  10. THE ADAPTIVE NATURE OF THE CORRELATIION DEPENDENCES WHICH DETERMINE THE PRODUCTIVITY OF THE MAIN SPIKE IN CULTIVARS AND HYBRIDS OF WINTER WHEAT GROWN ON THE BLACK LEACHED SOIL OF CENTRAL CISCAUCASIA

    Oleynik A. A.

    2014-05-01

    Full Text Available This article discusses the adaptive nature of the correlations between the elements and sub-elements of the productivity of main spike of the F1, and F2 hybrids, constant breeding lines (F3, F4 and parental varieties. We have shown the possibility to determine the individual components of spike productivity with a selective advantage in the selection of winter wheat on the adaptability and efficiency in the conditions of the region

  11. Incremental learning algorithm for spike pattern classification

    Mohemmed, A; Kasabov, N

    2012-01-01

    In a previous work (Mohemmed et al.), the authors proposed a supervised learning algorithm to train a spiking neuron to associate input/output spike patterns. In this paper, the association learning rule is applied in training a single layer of spiking neurons to classify multiclass spike patterns whereby the neurons are trained to recognize an input spike pattern by emitting a predetermined spike train. The training is performed in incremental fashion, i.e. the synaptic weights are adjusted ...

  12. Spikes removal in surface measurement

    Several cylinder surface topographies made from grey cast iron were measured by Talysurf CCI white light interferometer with and without use of spikes filter. They were plateau honed by abrasive stones. Measured area was 3.3 mm × 3.3 mm, height resolution was 0.01 nm. The forms were eliminated using polynomial of the 3rd degree. After it, spikes were removed using four methods. These approaches were compared. Parameters of the smaller and highest sensitivity on spikes presence were selected

  13. Procedures for determination of 239,240Pu, 241Am, 237Np, 234,238U, 228,230,232Th, 99Tc and 210Pb-210Po in environmental material

    Since 1987, the Department of Nuclear Safety Research, Risoe National Laboratory has developed procedures for analysis of low-level amounts of radioactivity in large samples of 200 liters seawater, 10 gram sediment, soil and other environmental materials. These analytical procedures provide high chemical yields, good resolution and excellent decontamination factors for large environmental samples analysed by alpha spectrometry and mass spectrometry (ICPMS). The procedures have been checked through practical analysis work and are used in Norway, the Netherlands, Germany, Spain, France and Denmark. (au)

  14. Chemical fractionation of some natural radionuclides in a soil contaminated by slags

    To investigate the chemical fractionation of 238U, 226Ra, 210Pb, and 228Ra in soils contaminated by slags from coal firing and from pyrite roasting, a sequential extraction method (modified Tessier procedure) has been applied. The following fractions were each extracted: 1, easily exchangeable; 2, bound to carbonates; 3, bound to iron-manganese oxides; 4; bound to organic matter; 5, persistently bound; 6, residual. In addition, the extractants were also analyzed for the insoluble matrix elements Al and Fe to provide some information on the effect of each extraction step on the dissolution of the matrix. The results show that the percentage amounts of these radio-nuclide in fractions 1 (238U and 210Pb released from the slag by the iron-manganese oxide extractant are subsequently reabsorbed rapidly to a considerable extent by soil minerals and thus do not appear in the iron-manganese oxide fraction 3 but rather in fractions 4 and 6. As a result of such redistribution processes, it will be almost impossible to predict quantitatively the chemical fractionation of radionuclides in contaminated soils by investigating pure slags only. 24 refs., 2 figs., 2 tabs

  15. Wavelet analysis of epileptic spikes

    Latka, M; Kozik, A; West, B J; Latka, Miroslaw; Was, Ziemowit; Kozik, Andrzej; West, Bruce J.

    2003-01-01

    Interictal spikes and sharp waves in human EEG are characteristic signatures of epilepsy. These potentials originate as a result of synchronous, pathological discharge of many neurons. The reliable detection of such potentials has been the long standing problem in EEG analysis, especially after long-term monitoring became common in investigation of epileptic patients. The traditional definition of a spike is based on its amplitude, duration, sharpness, and emergence from its background. However, spike detection systems built solely around this definition are not reliable due to the presence of numerous transients and artifacts. We use wavelet transform to analyze the properties of EEG manifestations of epilepsy. We demonstrate that the behavior of wavelet transform of epileptic spikes across scales can constitute the foundation of a relatively simple yet effective detection algorithm.

  16. Computing with Spiking Neuron Networks

    Paugam-Moisy, H.; Bohte, Sander; Rozenberg, G.; Baeck, Thomas; Kok, Joost

    2012-01-01

    Abstract Spiking Neuron Networks (SNNs) are often referred to as the 3rd gener- ation of neural networks. Highly inspired from natural computing in the brain and recent advances in neurosciences, they derive their strength and interest from an ac- curate modeling of synaptic interactions between neurons, taking into account the time of spike firing. SNNs overcome the computational power of neural networks made of threshold or sigmoidal units. Based on dynamic event-driven processing, they ope...

  17. An investigation into the upward transport of uranium-series radionuclides in soils and uptake by plants

    assume that both 210Pb and 210Po can be treated as being present in secular equilibrium with the 226Ra. This simplification is not always appropriate. Where geochemical conditions are such that the 226Ra migrates upward in the soil column faster than 210Pb and 210Po, disequilibrium is not a significant issue, as the 226Ra supports 210Pb and 210Po at concentrations somewhat below those estimated on the basis of assumed secular equilibrium. However, for low, but realistic, values of the distribution coefficients for 210Pb and 210Po and high, but realistic, distribution coefficients for 226Ra, the 210Pb and 210Po can reach the surface soil in high concentrations that are not locally supported by 226Ra. This means that models based on the assumption of secular equilibrium should not be employed without a careful consideration of the hydrological and hydrochemical situation of interest. (paper)

  18. Learning Precise Spike Train to Spike Train Transformations in Multilayer Feedforward Neuronal Networks

    Banerjee, Arunava

    2014-01-01

    We derive a synaptic weight update rule for learning temporally precise spike train to spike train transformations in multilayer feedforward networks of spiking neurons. The framework, aimed at seamlessly generalizing error backpropagation to the deterministic spiking neuron setting, is based strictly on spike timing and avoids invoking concepts pertaining to spike rates or probabilistic models of spiking. The derivation is founded on two innovations. First, an error functional is proposed th...

  19. Comparison of magnetoencephalographic spikes with and without concurrent electroencephalographic spikes in extratemporal epilepsy.

    Park, Hyeon-Mi; Nakasato, Nobukazu; Iwasaki, Masaki; Shamoto, Hiroshi; Tominaga, Teiji; Yoshimoto, Takashi

    2004-07-01

    Interictal spikes in patients with epilepsy may be detected by either electroencephalography (EEG) (E-spikes) or magnetoencephalography (MEG) (M-spikes), or both MEG and EEG (E/M-spikes). Localization and amplitude were compared between E/M-spikes and M-spikes in 7 adult patients with extratemporal epilepsy to evaluate the clinical significance of MEG spikes. MEG and EEG were simultaneously measured using a helmet-shaped MEG system with planar-type gradiometers and scalp electrodes of the international 10-20 system. Sources of E/M-spikes and M-spikes were estimated by an equivalent current dipole (ECD) model for MEG at peak latency. Each subject showed 9 to 20 (mean 13.4) E/M-spikes and 9 to 31 (mean 16.3) M-spikes. No subjects showed significant differences in the ECD locations between E/M- and M-spikes. ECD moments of the E/M-spikes were significantly larger in 2 patients and not significantly different in the other 5 patients. The similar localizations of E/M-spikes and M-spikes suggest that combination of MEG and EEG is useful to detect more interictal spikes in patients with extratemporal epilepsy. The smaller tendency of ECD amplitude of the M-spikes than E/M-spikes suggests that scalp EEG may overlook small tangential spikes due to background brain noise. Localization value of M-spikes is clinically equivalent to that of E/M-spikes. PMID:15240925

  20. Radioactivity in soils of the Sao Paulo State, Brazil

    Full text: For proper management of soil and groundwater quality, background levels of toxic elements in a given ecosystem must be known. The main aim of the present study is to perform a radioactive characterization of representative soils from the Sao Paulo State, in order to determine background levels for some selected radionuclides, which could be used as a quality reference value. Soil types and sampling places were chosen according to their representativeness and spatial distribution in the State geological formations, taking also into account their nearness to large urban areas. Thirty samples were collected in areas presenting low antrophic perturbation - native vegetation or ancient reforestation -, minimizing the chances that selected areas could have sustained antrophic effects in recent past. Activity concentration of U-nat, Th-nat, 228Th, 228Ra, 226Ra, 210Pb, 137Cs and 40K were evaluated and correlated with soil mineralogical characteristics. The samples were measured by means of passive gamma spectrometry and spectrophotometry, employing Arsenazo III. Results showed a wide variation on background levels for natural radionuclides of the uranium and thorium series, and very low concentration of 137Cs from radioactive fallout, ranging from -1 for U-nat, 8 to 82 Bq.kg-1 for Th-nat, 4.8 to 120 Bq.kg-1 for 228Th, 3.3 to 97.6 Bq.kg-1 for 228Ra, 1.0 to 61.8 Bq.kg-1 for 226Ra, -1 for 210Pb, 0.8 to 4.1 Bq.kg-1 for 137Cs and 15.3 to 516 Bq.kg-1 for 40 K. No significant correlation could be observed between the clay, silt and sand content in the samples and the respective activity concentration of the radionuclides. (author)

  1. Learning Universal Computations with Spikes

    Thalmeier, Dominik; Uhlmann, Marvin; Kappen, Hilbert J.; Memmesheimer, Raoul-Martin

    2016-01-01

    Providing the neurobiological basis of information processing in higher animals, spiking neural networks must be able to learn a variety of complicated computations, including the generation of appropriate, possibly delayed reactions to inputs and the self-sustained generation of complex activity patterns, e.g. for locomotion. Many such computations require previous building of intrinsic world models. Here we show how spiking neural networks may solve these different tasks. Firstly, we derive constraints under which classes of spiking neural networks lend themselves to substrates of powerful general purpose computing. The networks contain dendritic or synaptic nonlinearities and have a constrained connectivity. We then combine such networks with learning rules for outputs or recurrent connections. We show that this allows to learn even difficult benchmark tasks such as the self-sustained generation of desired low-dimensional chaotic dynamics or memory-dependent computations. Furthermore, we show how spiking networks can build models of external world systems and use the acquired knowledge to control them. PMID:27309381

  2. A nonparametric Bayesian alternative to spike sorting

    Wood, Frank; Black, Michael J.

    2008-01-01

    The analysis of extra-cellular neural recordings typically begins with careful spike sorting and all analysis of the data then rests on the correctness of the resulting spike trains. In many situations this is unproblematic as experimental and spike sorting procedures often focus on well isolated units. There is evidence in the literature, however, that errors in spike sorting can occur even with carefully collected and selected data. Additionally, chronically implanted electrodes and arrays ...

  3. Parallel Algorithms for Neuronal Spike Sorting

    Bergheim, Thomas Stian; Skogvold, Arve Aleksander Nymo

    2011-01-01

    Neurons communicate through electrophysiological signals, which may be recorded using electrodes inserted into living tissue.When a neuron emits a signal, it is referred to as a spike, and an electrode can detect these from multiple neurons.Neuronal spike sorting is the process of classifying the spike activity based on which neuron each spike signal is emitted from.Advances in technology have introduced better recording equipment, which allows the recording of many neurons at the same time.H...

  4. Distribution of radionuclides in surface soils, Singhbhum Shear Zone, India and associated dose.

    Patra, A C; Sahoo, S K; Tripathi, R M; Puranik, V D

    2013-09-01

    Gamma emitters were estimated in surface soils from a mineralized zone in Eastern India using high purity Germanium detector-based high resolution gamma spectrometry system. Activities of (238)U, (226)Ra, (232)Th, (235)U, (227)Th, (234 m)Pa, (210)Pb, (40)K, and (137)Cs were 79 ± 50, 81 ± 53, 65 ± 23, 4 ± 2, 5 ± 4, 92 ± 50, 97 ± 45, 517 ± 201, and 4 ± 2 Bq/kg, respectively. Most radionuclides were observed to follow log-normal distribution. The correlation between physicochemical properties of the samples, like pH, organic matter content, particle size, and moisture content were also studied. Activity ratios of (226)Ra/(238)U, (210)Pb/(226)Ra, and (227)Th/(235)U indicated deviation from secular equilibrium in some samples. The associated annual effective dose ranged from 0.07 to 0.24 mSv and the mean was calculated to be 0.12 ± 0.04 mSv for this region, indicating it to be one of normal natural background radiation. PMID:23456273

  5. Automatic spikes detection in seismogram

    王海军; 靳平; 刘贵忠

    2003-01-01

    @@ Data processing for seismic network is very complex and fussy, because a lot of data is recorded in seismic network every day, which make it impossible to process these data all by manual work. Therefore, seismic data should be processed automatically to produce a initial results about events detection and location. Afterwards, these results are reviewed and modified by analyst. In automatic processing data quality checking is important. There are three main problem data thatexist in real seismic records, which include: spike, repeated data and dropouts. Spike is defined as isolated large amplitude point; the other two problem datahave the same features that amplitude of sample points are uniform in a interval. In data quality checking, the first step is to detect and statistic problem data in a data segment, if percent of problem data exceed a threshold, then the whole data segment is masked and not be processed in the later process.

  6. Assessment of soil erosion and effectiveness of soil conservation measures in China

    China is one of the countries suffering from the most serious soil erosion in the world. For the Loess Plateau and the North-Eastern China, severe water erosion is the major cause, resulting from the intensive tillage operations and potato growing on steep slopes in the Loess Plateau and downslope cultivation and inappropriate crop rotation in North East-China. For the North China site, wind erosion is the main process, resulting from conventional tillage operations without surface cover. In South West (SW) China, the overgrazing is considered a major cause of accelerated soil and water loss. IAEA-funded studies were conducted in the Loess Plateau (Nianzhuang watershed in Yan'an), North China (Fengning site), North East China (Baiquan site), and SW China (Xichang site). Results obtained show that soil erosion rates from cultivated land as measured by fallout radionuclides (137Cs, 210Pb, and 7Be) are substantial. Soil erosion rates, as measured by the fallout radionuclide tracer method, declined by 16 to 80% depending on the type of conservation measure (terraced hillslopes, vegetated hillslopes, contour cultivation and no tillage, species of vegetation) and the studied sites, highlighting the importance of the use of radionuclide tracers in targeting the appropriate soil conservation measures to sites with different levels and types of erosion. The information gained from IAEA-funded studies has been adopted by the Office of the World Bank Project in Baota district, Yan'an for selecting effective soil conservation measures to control soil erosion

  7. Evolutionary Bits'n'Spikes

    D. Floreano; Schoeni, N.; Caprari, G.; Blynel, J.; Standish, R. K.; Beadau, M. A.; Abbass, H. A.

    2002-01-01

    We describe a model and implementation of evolutionary spiking neurons for embedded microcontrollers with few bytes of memory and very low power consumption. The approach is tested with an autonomous microrobot of less than 1 in^3 that evolves the ability to move in a small maze without human intervention and external computers. Considering the very large diffusion, small size, and low cost of embedded microcontrollers, the approach described here could find its way in several intelligent dev...

  8. iSpike: a spiking neural interface for the iCub robot

    This paper presents iSpike: a C++ library that interfaces between spiking neural network simulators and the iCub humanoid robot. It uses a biologically inspired approach to convert the robot’s sensory information into spikes that are passed to the neural network simulator, and it decodes output spikes from the network into motor signals that are sent to control the robot. Applications of iSpike range from embodied models of the brain to the development of intelligent robots using biologically inspired spiking neural networks. iSpike is an open source library that is available for free download under the terms of the GPL. (paper)

  9. iSpike: a spiking neural interface for the iCub robot.

    Gamez, D; Fidjeland, A K; Lazdins, E

    2012-06-01

    This paper presents iSpike: a C++ library that interfaces between spiking neural network simulators and the iCub humanoid robot. It uses a biologically inspired approach to convert the robot's sensory information into spikes that are passed to the neural network simulator, and it decodes output spikes from the network into motor signals that are sent to control the robot. Applications of iSpike range from embodied models of the brain to the development of intelligent robots using biologically inspired spiking neural networks. iSpike is an open source library that is available for free download under the terms of the GPL. PMID:22617339

  10. Spike voltage topography in temporal lobe epilepsy.

    Asadi-Pooya, Ali A; Asadollahi, Marjan; Shimamoto, Shoichi; Lorenzo, Matthew; Sperling, Michael R

    2016-07-15

    We investigated the voltage topography of interictal spikes in patients with temporal lobe epilepsy (TLE) to see whether topography was related to etiology for TLE. Adults with TLE, who had epilepsy surgery for drug-resistant seizures from 2011 until 2014 at Jefferson Comprehensive Epilepsy Center were selected. Two groups of patients were studied: patients with mesial temporal sclerosis (MTS) on MRI and those with other MRI findings. The voltage topography maps of the interictal spikes at the peak were created using BESA software. We classified the interictal spikes as polar, basal, lateral, or others. Thirty-four patients were studied, from which the characteristics of 340 spikes were investigated. The most common type of spike orientation was others (186 spikes; 54.7%), followed by lateral (146; 42.9%), polar (5; 1.5%), and basal (3; 0.9%). Characteristics of the voltage topography maps of the spikes between the two groups of patients were somewhat different. Five spikes in patients with MTS had polar orientation, but none of the spikes in patients with other MRI findings had polar orientation (odds ratio=6.98, 95% confidence interval=0.38 to 127.38; p=0.07). Scalp topographic mapping of interictal spikes has the potential to offer different information than visual inspection alone. The present results do not allow an immediate clinical application of our findings; however, detecting a polar spike in a patient with TLE may increase the possibility of mesial temporal sclerosis as the underlying etiology. PMID:27288809

  11. Statistical analysis of spikes in bioburden

    A spike in a set of bioburden data can be considered a bioburden number or numbers that are several times greater in value than the average value of the data set. A spike is not considered a manifestation of a quality issue, but a consistent component of product bioburden that should be taken into account in establishing the minimum acceptable dose in the radiation sterilization process. Rather than a subjective approach, statistical techniques were used to determine when a bioburden number or numbers represent spikes in a set of bioburden data. Bioburden data taken from a cross section of different products over a few months were analyzed. Results of the study identified spikes when the spike bioburden was approximately three or more times the average bioburden for the data set. In those cases where bioburden spikes were identified, use of the spike bioburden rather than the average bioburden increased the sterilization dose by up to 10%.

  12. Statistical analysis of spikes in bioburden

    Fairand, Barry P.; Le, Vu; Tumaitis, Zabrina

    2012-08-01

    A spike in a set of bioburden data can be considered a bioburden number or numbers that are several times greater in value than the average value of the data set. A spike is not considered a manifestation of a quality issue, but a consistent component of product bioburden that should be taken into account in establishing the minimum acceptable dose in the radiation sterilization process. Rather than a subjective approach, statistical techniques were used to determine when a bioburden number or numbers represent spikes in a set of bioburden data. Bioburden data taken from a cross section of different products over a few months were analyzed. Results of the study identified spikes when the spike bioburden was approximately three or more times the average bioburden for the data set. In those cases where bioburden spikes were identified, use of the spike bioburden rather than the average bioburden increased the sterilization dose by up to 10%.

  13. Enhancement of the 1985 Browns Ferry exercise through the use of spiked samples

    The use of spiked environmental samples has proven to be a beneficial part of nuclear power plant exercises. Milk, soil, and air sampling cartridges can easily be spiked with realistic concentrations of radionuclide without violating Nuclear Regulatory Commission regulations or policy and with no significant radiation hazard to exercise participants. Analysis and reporting of data from realistic samples significantly improves motivation, attitude, moral, and overall preparedness of the individuals participating in that phase of the exercise

  14. Threshold increases in soil lead and mercury from tropospheric deposition across an elevational gradient.

    Stankwitz, Clare; Kaste, James M; Friedland, Andrew J

    2012-08-01

    Atmospheric deposition is the primary mechanism by which remote ecosystems are contaminated, but few data sets show how fluxes change and control soil metal burdens at the landform scale. We present mercury (Hg), lead ((210)Pb and total Pb), and cosmogenic beryllium-7 ((7)Be) measurements in organic (O) soil horizons at high-resolution elevation intervals of ∼60 m from 540 to 1160 m on Camels Hump in northern Vermont, USA. Across this gradient, average O horizon Hg ranges from 0.99 mg m(-2) in the low elevation deciduous forest zone to 7.6 mg m(-2) in the higher elevation coniferous forest at 1030 m. We measure two pronounced threshold increases in soil metal burdens above 801 and 934 m, corresponding to the two most common altitudes of cloud base, which coincide with changes in vegetation species. Lead-210, a unique tracer of tropospheric deposition, also increased from 3200 Bq m(-2) to 11500 Bq m(-2) in O horizons, exhibiting threshold responses at the same elevations as Hg and total Pb. Concentrations of (210)Pb and Hg in foliage double from 760 to 900 m elevation, indicating enhanced deposition across the transition from deciduous to coniferous forest. In contrast, (7)Be is constant across the entire elevational gradient because of its upper atmospheric source. This indicates that the effects of orographic precipitation have a smaller control on soil contaminant burdens than the coupled cloudwater deposition-vegetation scavenging effect in the presence of upwind sources. By measuring soil contaminants and unique tracers of atmospheric deposition, we show that tropospheric fluxes of Hg and Pb are higher by a factor of 2 in high-elevation coniferous forests than in adjacent lowlands. Total O horizon Hg and Pb burdens increase by over 4-fold with elevation because of the compounding effects of enhanced deposition and longer metal residence times at higher elevations (>50 years). PMID:22759071

  15. Spikes in Quantum Regge Calculus

    Ambjorn, J.; Nielsen, J.; Rolf, J.; Savvidy, G.

    1997-01-01

    We demonstrate by explicit calculation of the DeWitt-like measure in two-dimensional quantum Regge gravity that it is highly non-local and that the average values of link lengths $l, $, do not exist for sufficient high powers of $n$. Thus the concept of length has no natural definition in this formalism and a generic manifold degenerates into spikes. This might explain the failure of quantum Regge calculus to reproduce the continuum results of two-dimensional quantum gravity. It points to sev...

  16. Multiscale analysis of neural spike trains.

    Ramezan, Reza; Marriott, Paul; Chenouri, Shojaeddin

    2014-01-30

    This paper studies the multiscale analysis of neural spike trains, through both graphical and Poisson process approaches. We introduce the interspike interval plot, which simultaneously visualizes characteristics of neural spiking activity at different time scales. Using an inhomogeneous Poisson process framework, we discuss multiscale estimates of the intensity functions of spike trains. We also introduce the windowing effect for two multiscale methods. Using quasi-likelihood, we develop bootstrap confidence intervals for the multiscale intensity function. We provide a cross-validation scheme, to choose the tuning parameters, and study its unbiasedness. Studying the relationship between the spike rate and the stimulus signal, we observe that adjusting for the first spike latency is important in cross-validation. We show, through examples, that the correlation between spike trains and spike count variability can be multiscale phenomena. Furthermore, we address the modeling of the periodicity of the spike trains caused by a stimulus signal or by brain rhythms. Within the multiscale framework, we introduce intensity functions for spike trains with multiplicative and additive periodic components. Analyzing a dataset from the retinogeniculate synapse, we compare the fit of these models with the Bayesian adaptive regression splines method and discuss the limitations of the methodology. Computational efficiency, which is usually a challenge in the analysis of spike trains, is one of the highlights of these new models. In an example, we show that the reconstruction quality of a complex intensity function demonstrates the ability of the multiscale methodology to crack the neural code. PMID:23996238

  17. Assessment of soil erosion and deposition rates in a Moroccan agricultural field using fallout 137Cs and 210Pbex.

    Benmansour, M; Mabit, L; Nouira, A; Moussadek, R; Bouksirate, H; Duchemin, M; Benkdad, A

    2013-01-01

    In Morocco land degradation - mainly caused by soil erosion - is one of the most serious agroenvironmental threats encountered. However, only limited data are available on the actual magnitude of soil erosion. The study site investigated was an agricultural field located in Marchouch (6°42' W, 33° 47' N) at 68 km south east from Rabat. This work demonstrates the potential of the combined use of (137)Cs, (210)Pb(ex) as radioisotopic soil tracers to estimate mid and long term erosion and deposition rates under Mediterranean agricultural areas. The net soil erosion rates obtained were comparable, 14.3 t ha(-1) yr(-1) and 12.1 ha(-1) yr(-1) for (137)Cs and (210)Pb(ex) respectively, resulting in a similar sediment delivery ratio of about 92%. Soil redistribution patterns of the study field were established using a simple spatialisation approach. The resulting maps generated by the use of both radionuclides were similar, indicating that the soil erosion processes has not changed significantly over the last 100 years. Over the previous 10 year period, the additional results provided by the test of the prediction model RUSLE 2 provided results of the same order of magnitude. Based on the (137)Cs dataset established, the contribution of the tillage erosion impact has been evaluated with the Mass Balance Model 3 and compared to the result obtained with the Mass Balance Model 2. The findings highlighted that water erosion is the leading process in this Moroccan cultivated field, tillage erosion under the experimental condition being the main translocation process within the site without a significant and major impact on the net erosion. PMID:22898495

  18. User-Guided Interictal Spike Detection

    El-Gohary, Mahmoud; McNames, James; Elsas, Siegward-M.

    2008-01-01

    In the diagnosis and treatment of epilepsy, long-term monitoring may be required to document and study interictal activities such as interictal spikes. However, visual inspection of the EEG done by an expert is too time consuming and researchers normally resort to automatic detection methods. We describe a new EEG user-guided interictal spike detection algorithm that only requires the user to annotate a few spikes. We use the annotations to build a template that captures the relevant features...

  19. Indisputable facts when implementing spiking neuron networks

    Cessac, Bruno; Paugam-Moisy, Hélène; Viéville, Thierry

    2009-01-01

    In this article, our wish is to demystify some aspects of coding with spike-timing, through a simple review of well-understood technical facts regarding spike coding. The goal is to help better understanding to which extend computing and modelling with spiking neuron networks can be biologically plausible and computationally efficient. We intentionally restrict ourselves to a deterministic dynamics, in this review, and we consider that the dynamics of the network is defined by a non-stochasti...

  20. Spiking Deep Networks with LIF Neurons

    Hunsberger, Eric; Eliasmith, Chris

    2015-01-01

    We train spiking deep networks using leaky integrate-and-fire (LIF) neurons, and achieve state-of-the-art results for spiking networks on the CIFAR-10 and MNIST datasets. This demonstrates that biologically-plausible spiking LIF neurons can be integrated into deep networks can perform as well as other spiking models (e.g. integrate-and-fire). We achieved this result by softening the LIF response function, such that its derivative remains bounded, and by training the network with noise to prov...

  1. Supervised Learning in Multilayer Spiking Neural Networks

    Sporea, Ioana

    2012-01-01

    The current article introduces a supervised learning algorithm for multilayer spiking neural networks. The algorithm presented here overcomes some limitations of existing learning algorithms as it can be applied to neurons firing multiple spikes and it can in principle be applied to any linearisable neuron model. The algorithm is applied successfully to various benchmarks, such as the XOR problem and the Iris data set, as well as complex classifications problems. The simulations also show the flexibility of this supervised learning algorithm which permits different encodings of the spike timing patterns, including precise spike trains encoding.

  2. Multineuronal Spike Sequences Repeat with Millisecond Precision

    Yuji Ikegaya

    2013-06-01

    Full Text Available Cortical microcircuits are nonrandomly wired by neurons. As a natural consequence, spikes emitted by microcircuits are also nonrandomly patterned in time and space. One of the prominent spike organizations is a repetition of fixed patterns of spike series across multiple neurons. However, several questions remain unsolved, including how precisely spike sequences repeat, how the sequences are spatially organized, how many neurons participate in sequences, and how different sequences are functionally linked. To address these questions, we monitored spontaneous spikes of hippocampal CA3 neurons ex vivo using a high-speed functional multineuron calcium imaging technique that allowed us to monitor spikes with millisecond resolution and to record the location of spiking and nonspiking neurons. Multineuronal spike sequences were overrepresented in spontaneous activity compared to the statistical chance level. Approximately 75% of neurons participated in at least one sequence during our observation period. The participants were sparsely dispersed and did not show specific spatial organization. The number of sequences relative to the chance level decreased when larger time frames were used to detect sequences. Thus, sequences were precise at the millisecond level. Sequences often shared common spikes with other sequences; parts of sequences were subsequently relayed by following sequences, generating complex chains of multiple sequences.

  3. Connecting Spiking Neurons to a Spiking Memristor Network Changes the Memristor Dynamics

    Gater, Deborah; Iqbal, Attya; Davey, Jeffrey; Gale, Ella

    2014-01-01

    Memristors have been suggested as neuromorphic computing elements. Spike-time dependent plasticity and the Hodgkin-Huxley model of the neuron have both been modelled effectively by memristor theory. The d.c. response of the memristor is a current spike. Based on these three facts we suggest that memristors are well-placed to interface directly with neurons. In this paper we show that connecting a spiking memristor network to spiking neuronal cells causes a change in the memristor network dyna...

  4. Learning Precise Spike Train-to-Spike Train Transformations in Multilayer Feedforward Neuronal Networks.

    Banerjee, Arunava

    2016-05-01

    We derive a synaptic weight update rule for learning temporally precise spike train-to-spike train transformations in multilayer feedforward networks of spiking neurons. The framework, aimed at seamlessly generalizing error backpropagation to the deterministic spiking neuron setting, is based strictly on spike timing and avoids invoking concepts pertaining to spike rates or probabilistic models of spiking. The derivation is founded on two innovations. First, an error functional is proposed that compares the spike train emitted by the output neuron of the network to the desired spike train by way of their putative impact on a virtual postsynaptic neuron. This formulation sidesteps the need for spike alignment and leads to closed-form solutions for all quantities of interest. Second, virtual assignment of weights to spikes rather than synapses enables a perturbation analysis of individual spike times and synaptic weights of the output, as well as all intermediate neurons in the network, which yields the gradients of the error functional with respect to the said entities. Learning proceeds via a gradient descent mechanism that leverages these quantities. Simulation experiments demonstrate the efficacy of the proposed learning framework. The experiments also highlight asymmetries between synapses on excitatory and inhibitory neurons. PMID:26942750

  5. Elevated CO2 increases Cs uptake and alters microbial communities and biomass in the rhizosphere of Phytolacca americana Linn (pokeweed) and Amaranthus cruentus L. (purple amaranth) grown on soils spiked with various levels of Cs

    General concern about increasing global atmospheric CO2 levels owing to the ongoing fossil fuel combustion and elevated levels of radionuclides in the environment, has led to growing interest in the responses of plants to interactive effects of elevated CO2 and radionuclides in terms of phytoremediation and food safety. To assess the combined effects of elevated CO2 and cesium contamination on plant biomass, microbial activities in the rhizosphere soil and Cs uptake, Phytolacca americana Linn (pokeweed, C3 specie) and Amaranthus cruentus L. (purple amaranth, C4 specie) were grown in pots of soils containing five levels of cesium (0, 100, 300, 500 and 1000 mg Cs kg−1) under two levels of CO2 (360 and 860 μL L−1, respectively). Shoot and root biomass of P. americana and Amaranthus crentus was generally higher under elevated CO2 than under ambient CO2 for all treatments. Both plant species exhibited higher Cs concentration in the shoots and roots under elevated CO2 than ambient CO2. For P. americana grown at 0, 100, 300, 500 and 1000 mg Cs kg−1, the increase magnitude of Cs concentration due to elevated CO2 was 140, 18, 11, 34 and 15% in the shoots, and 150, 20, 14, 15 and 19% in the roots, respectively. For A. cruentus, the corresponding value was 118, 28, 21, 14 and 17% in the shoots, and 126, 6, 11, 17 and 22% in the roots, respectively. Higher bioaccumulation factors were noted for both species grown under elevated CO2 than ambient CO2. The populations of bacteria, actinomycetes and fungi, and the microbial C and N in the rhizosphere soils of both species were higher at elevated CO2 than at ambient CO2 with the same concentration of Cs. The results suggested that elevated CO2 significantly affected plant biomass, Cs uptake, soil C and N concentrations, and community composition of soil microbes associated with P. americana and A. cruentus roots. The knowledge gained from this investigation constitutes an important advancement in promoting utilization of CO2

  6. Soils

    For Austria there exists a comprehensive soil data collection, integrated in a GIS (geographical information system). The content values of pollutants (cadmium, mercury, lead, copper, mercury, radio-cesium) are given in geographical charts and in tables by regions and by type of soil (forests, agriculture, greenland, others) for the whole area of Austria. Erosion effects are studied for the Austrian region. Legal regulations and measures for an effective soil protection, reduction of soil degradation and sustainable development in Austria and the European Union are discussed. (a.n.)

  7. A nonparametric Bayesian alternative to spike sorting

    Wood, Frank; Black, Michael J.

    2013-01-01

    The analysis of extra-cellular neural recordings typically begins with careful spike sorting and all analysis of the data then rests on the correctness of the resulting spike trains. In many situations this is unproblematic as experimental and spike sorting procedures often focus on well isolated units. There is evidence in the literature, however, that errors in spike sorting can occur even with carefully collected and selected data. Additionally, chronically implanted electrodes and arrays with fixed electrodes cannot be easily adjusted to provide well isolated units. In these situations, multiple units may be recorded and the assignment of waveforms to units may be ambiguous. At the same time, analysis of such data may be both scientifically important and clinically relevant. In this paper we address this issue using a novel probabilistic model that accounts for several important sources of uncertainty and error in spike sorting. In lieu of sorting neural data to produce a single best spike train, we estimate a probabilistic model of spike trains given the observed data. We show how such a distribution over spike sortings can support standard neuroscientific questions while providing a representation of uncertainty in the analysis. As a representative illustration of the approach, we analyzed primary motor cortical tuning with respect to hand movement in data recorded with a chronic multi-electrode array in non-human primates. We found that the probabilistic analysis generally agrees with human sorters but suggests the presence of tuned units not detected by humans. PMID:18602697

  8. Visually Evoked Spiking Evolves While Spontaneous Ongoing Dynamics Persist

    Huys, Raoul; Jirsa, Viktor K; Darokhan, Ziauddin; Valentiniene, Sonata; Roland, Per E

    2016-01-01

    by evoked spiking. This study of laminar recordings of spontaneous spiking and visually evoked spiking of neurons in the ferret primary visual cortex shows that the spiking dynamics does not change: the spontaneous spiking as well as evoked spiking is controlled by a stable and persisting fixed point......Neurons in the primary visual cortex spontaneously spike even when there are no visual stimuli. It is unknown whether the spiking evoked by visual stimuli is just a modification of the spontaneous ongoing cortical spiking dynamics or whether the spontaneous spiking state disappears and is replaced...... attractor. Its existence guarantees that evoked spiking return to the spontaneous state. However, the spontaneous ongoing spiking state and the visual evoked spiking states are qualitatively different and are separated by a threshold (separatrix). The functional advantage of this organization is that it...

  9. Stochastic Variational Learning in Recurrent Spiking Networks

    Danilo eJimenez Rezende

    2014-04-01

    Full Text Available The ability to learn and perform statistical inference with biologically plausible recurrent network of spiking neurons is an important step towards understanding perception and reasoning. Here we derive and investigate a new learning rule for recurrent spiking networks with hidden neurons, combining principles from variational learning and reinforcement learning. Our network defines a generative model over spike train histories and the derived learning rule has the form of a local Spike Timing Dependent Plasticity rule modulated by global factors (neuromodulators conveying information about ``novelty on a statistically rigorous ground.Simulations show that our model is able to learn bothstationary and non-stationary patterns of spike trains.We also propose one experiment that could potentially be performed with animals in order to test the dynamics of the predicted novelty signal.

  10. PySpike - A Python library for analyzing spike train synchrony

    Mulansky, Mario

    2016-01-01

    Understanding how the brain functions is one of the biggest challenges of our time. The analysis of experimentally recorded neural firing patterns (spike trains) plays a crucial role in addressing this problem. Here, the PySpike library is introduced, a Python package for spike train analysis providing parameter-free and time-scale independent measures of spike train synchrony. It allows to compute bi- and multivariate dissimilarity profiles, averaged values and bivariate matrices. Although mainly focusing on neuroscience, PySpike can also be applied in other contexts like climate research or social sciences. The package is available as Open Source on Github and PyPI.

  11. Spiking neural P systems with anti-spikes and without annihilating priority as number acceptors

    Gangjun Tan,Tao Song,; Zhihua Chen

    2014-01-01

    Spiking neural P systems with anti-spikes (ASN P sys-tems) are variant forms of spiking neural P systems, which are inspired by inhibitory impulses/spikes or inhibitory synapses. The typical feature of ASN P systems is when a neuron contains both spikes and anti-spikes, spikes and anti-spikes wil immediately an-nihilate each other in a maximal way. In this paper, a restricted variant of ASN P systems, cal ed ASN P systems without anni-hilating priority, is considered, where the annihilating rule is used as the standard rule, i.e., it is not obligatory to use in the neuron associated with both spikes and anti-spikes. If the annihilating rule is used in a neuron, the annihilation wil consume one time unit. As a result, such systems using two categories of spiking rules (iden-tified by (a, a) and (a, ¯a)) can achieve Turing completeness as number accepting devices.

  12. Cluster-based spike detection algorithm adapts to interpatient and intrapatient variation in spike morphology.

    Nonclercq, Antoine; Foulon, Martine; Verheulpen, Denis; De Cock, Cathy; Buzatu, Marga; Mathys, Pierre; Van Boga