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Sample records for 210pb spiked soils

  1. {sup 210}Po and {sup 210}Pb in Forest Soil and in Wild Berries in Finland

    SciTech Connect

    Vaaramaa, Kaisa; Lehto, Jukka; Solatie, Dina; Aro, Lasse

    2008-08-07

    The behaviour of {sup 210}Po and {sup 210}Pb was investigated in forests in the Southern Finland site and in the Northern Finland site. Sampling sites were in Scots pine (Pinus sylvestris) forests. Maximum activities of {sup 210}Po and {sup 210}Pb in soil columns were found in organic layers. According to preliminary results of wild berry samples, the lowest {sup 210}Po concentrations were found in berries. The highest concentration of {sup 210}Po was found in stems of the blueberry (Vaccinium myrtillus) and the lingonberry (Vaccinium vitis-idaea) samples.

  2. [Using 137Cs and 210Pb(ex) to trace the impact of soil erosion on soil organic carbon at a slope farmland in the black soil region].

    PubMed

    Fang, Hai-Yan; Sheng, Mei-Ling; Sun, Li-Ying; Cai, Qiang-Guo

    2013-07-01

    Soil cores were collected from a 28.5 hm2 slope farmland in the black soil region of Northeast China. Based on the sampled data of 137Cs, 210Pb(ex) and SOC, the potentials of applying 137Cs and 210Pb(ex) for assessing SOC redistribution were evaluated, aimed to approach the impact of soil erosion on soil organic carbon (SOC) in black soil region. At both planar and vertical directions, the 137Cs, 210Pb(ex) and SOC in the farmland had similar distribution patterns. Although there were large planar variations in the 137Cs and 210Pb(ex) areal activities and the SOC stock as affected by soil erosion and deposition, the 137Cs, 210Pb(ex) and SOC had similar changing trends over the landscape. Two depth distribution profiles were also used to study the relations of 137Cs and 210Pb(ex) with SOC. At eroded site, the radioactivities of 137Cs and 210Pb(ex) and the SOC mass fraction did not show large variations in 0-25 cm soil layer, but decreased sharply below 25 cm. For the deposition sample, the radioactivities of 137Cs and 210Pb(ex) in 0-100 cm soil increased firstly and then decreased. The SOC mass fraction also had similar depth distribution pattern in this soil layer. The 137Cs and 210Pb(ex) presented positive linear correlations with the SOC, indicating that 137Cs, 210Pb(ex) and SOC moved with the same physical mechanism in the farmland, and fallout 137Cs and 210Pb(ex) could be used to study spatio-temporal distribution characteristics of SOC in the black soil region under the condition of soil erosion. PMID:24175514

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

    PubMed

    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

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

    PubMed

    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

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

    PubMed

    Matisoff, Gerald

    2014-12-01

    Although (137)Cs 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 (210)Pb ((210)Pbxs) to study the same processes. Furthermore, since (137)Cs activities in soils are decreasing because of radioactive decay, some locations have an added complication due to the addition of Chernobyl-derived (137)Cs, and the activities of (137)Cs in the southern hemisphere are low, there is a need to develop techniques that use (210)Pbxs to provide estimates of rates of soil erosion and particle transport. This paper reviews the current status of (210)Pbxs 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 (210)Pbxs are based on the unsupported (210)Pb ((210)Pbxs) inventory in the soil, the depth distribution of (210)Pbxs, 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 (210)Pbxs to the soil surface and the post-depositional mobility of (210)Pb are also discussed. (210)Pb can be used as one tracer to permit sediment source area identification. This sediment 'fingerprinting' has been extended far beyond using (210)Pb 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

  6. (The determination of sup 222 Rn flux from soils based on sup 210 Pb and sup 226 Ra disequilibrium)

    SciTech Connect

    Turekian, K.K.

    1991-01-01

    The emanating fraction of radon in soils from the southern part of the United States is about 40% greater than in those from the northern part. The mean {sup 226}Ra activity in the southern soils is also slightly higher and as a consequence the {sup 222}Rn flux derived from the top 50 cm. is greater in the southern samples. We tentatively attribute these observations to the greater degree of weathering associated with the pre-glacial age of the parent material of many of the southern soils. The weathering has concentrated {sup 226}Ra near grain surfaces and results in an increased emanating power for {sup 222}Rn. The estimated correction in {sup 210}Pb analyses described above results in a small decrease in our estimate of the mean loss rate of {sup 222}Rn from the upper 50 cm of soils.

  7. 210Pb dating

    USGS Publications Warehouse

    Swarzenski, Peter W.

    2014-01-01

    Roughly fifty years ago, a small group of scientists from Belgium and the United States, trying to better constrain ice sheet accumulation rates, attempted to apply what was then know about environmental lead as a potential geochronometer. Thus Goldberg (1963) developed the first principles of the 210Pb dating method, which was soon followed by a paper by Crozaz et al. (1964), who examined accumulation history of Antarctic snow using 210Pb. Shortly thereafter, Koide et al. (1972, 1973) adapted this technique to unravel sediment deposition and accumulation records in deep-sea environments. Serendipitously, they chose to work in a deep basin off California, where an independent and robust age model had already been developed. Krishanswami et al. (1971) extended the use of this technique to lacustrine deposits to reconstruct depositional histories of lake sediment, and maybe more importantly, contaminant inputs and burial. Thus, the powerful tool for dating recent (up to about one century old) sediment deposits was established and soon widely adopted. Today almost all oceanographic or limnologic studies that address recent depositional reconstructions employ 210Pb as one of several possible geochronometers (Andrews et al., 2009; Gale, 2009; Baskaran, 2011; Persson and Helms, 2011). This paper presents a short overview of the principles of 210Pb dating and provides a few examples that illustrate the utility of this tracer in contrasting depositional systems. Potential caveats and uncertainties (Appleby et al., 1986; Binford, 1990; Binford et al., 1993; Smith, 2001; Hancock et al., 2002) inherent to the use and interpretation of 210Pb-derived age-models are also introduced. Recommendations as to best practices for most reliable uses and reporting are presented in the summary.

  8. Soil to rice transfer factors for (226)Ra, (228)Ra, (210)Pb, (40)K and (137)Cs: a study on rice grown in India.

    PubMed

    Karunakara, N; Rao, Chetan; Ujwal, P; Yashodhara, I; Kumara, Sudeep; Ravi, P M

    2013-04-01

    India is the second largest producer of rice (Oryza sativa L.) in the world and rice is an essential component of the diet for a majority of the population in India. However, detailed studies aimed at the evaluation of radionuclide transfer factors (F(v)) for the rice grown in India are almost non-existent. This paper presents the soil to rice transfer factors for natural ((226)Ra, (228)Ra, (40)K, and (210)Pb) and artificial ((137)Cs) radionuclides 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 and the water required for this field was drawn from the cooling water discharge canal of the power plant. For a comparative study of the radionuclide transfer factors, rice samples were also collected from the rice fields of nearby villages. The study showed that the (226)Ra and (228)Ra activity concentrations were below detection levels in different organs of the rice plant. The soil to un-hulled rice grain (40)K transfer factor varied in the range of 6.5 × 10(-1) to 2.9 with a mean of 0.15 × 10(1), and of (210)Pb varied in the range of <1.2 × 10(-2) to 8.1 × 10(-1) with a mean of 1.4 × 10(-1), and of (137)Cs varied in the range of 6.6 × 10(-2) to 3.4 × 10(-1) with a mean of 2.1 × 10(-1). The mean values of un-hulled grain to white rice processing retention factors (F(r)) were 0.12 for (40)K, 0.03 for (210)Pb, and 0.14 for (137)Cs. Using these processing retention factors, the soil to white rice transfer factors were estimated and these were found to have mean values of 1.8 × 10(-1), 4.2 × 10(-3), and 3.0 × 10(-2) for (40)K, (210)Pb, and (137)Cs, respectively. The study has shown that the transfer of (40)K was higher for above the ground organs than for the root, but (210)Pb and (137)Cs were retained in the root and their transfer to above the ground organs of the rice plant is significantly lower. PMID:23266913

  9. [The determination of {sup 222}Rn flux from soils based on {sup 210}Pb and {sup 226}Ra disequilibrium]. Progress report

    SciTech Connect

    Turekian, K.K.

    1991-12-31

    The emanating fraction of radon in soils from the southern part of the United States is about 40% greater than in those from the northern part. The mean {sup 226}Ra activity in the southern soils is also slightly higher and as a consequence the {sup 222}Rn flux derived from the top 50 cm. is greater in the southern samples. We tentatively attribute these observations to the greater degree of weathering associated with the pre-glacial age of the parent material of many of the southern soils. The weathering has concentrated {sup 226}Ra near grain surfaces and results in an increased emanating power for {sup 222}Rn. The estimated correction in {sup 210}Pb analyses described above results in a small decrease in our estimate of the mean loss rate of {sup 222}Rn from the upper 50 cm of soils.

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

    PubMed

    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. Variations of 210Pb concentrations in surface air at Thessaloniki, Greece (40°N)

    NASA Astrophysics Data System (ADS)

    Ioannidou, A.; Kotsopoulou, E.; Karanatsiou, A.; Papastefanou, C.

    2012-04-01

    Atmospheric concentrations of 210Pb were measured over the year 2009 in ground level air at Thessaloniki, Northern Greece (40°62' N, 22°95'E). The mean activity concentrations of 210Pb in surface air have been found to be 671 ± 213 μBq m-3. The highest values of monthly atmospheric concentrations of 210Pb were observed in the autumn and the lowest in the spring period. The higher values of 210Pb during autumn were attributed to frequent inversion conditions of the surface layers, resulting in an enrichment of radon and its decay products in surface air. The lower values during the winter months might be due to the low emanation of radon from the frozen or snow-covered soil. The minima of 210Pb concentrations during spring might reflect on higher washout during this period, which results in less emanation of radon from saturated with water soil, resulting in less production of 210Pb near ground-level air. The relative high values during summer are probably due to the higher 222Rn exhalation from the ground and due to the higher air mixing within the troposphere, which has as a result to carry down to the surface layer 210Pb whose origin is older air masses which entered into the free troposphere.

  12. Radiolead (210)Pb and (210)Po/(210)Pb activity ratios in dogs' hair.

    PubMed

    Strumińska-Parulska, Dagmara I; Szymańska, Karolina; Skwarzec, Bogdan

    2015-01-01

    The aim of this study was to determine activity concentrations of radiolead (210)Pb as well as (210)Po/(210)Pb activity ratios in dog hair. The objectives of this research were also to investigate the utility of domestic animal hair as a noninvasive indicator of metal exposure for radiotoxic, naturally occurring (210)Pb and find the correlations between (210)Pb concentration in hair and age, gender, hair type or diet of analyzed animals. The highest (210)Pb concentrations were measured in a 2-year-old Shih Tzus (9.82 ± 0.53 Bq kg(-1) dw(-1)) and a 2-year-old Bichon Maltese (8.09 ± 0.42 Bq kg(-1) dw(-1)), both longhair males, while the lowest was found in a 15-year-old Yorkshire Terrier (0.44 ± 0.02 Bq kg(-1) dw(-1)), small longhair male as well. As results showed, mainly dog hair color as well as their age and gender influenced the differences in the values of (210)Pb concentrations in analyzed hair samples. Also the values of activity ratios of (210)Po/(210)Pb in analyzed dog hair samples were calculated and obtained results were similar to those observed in human hair. PMID:26191992

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

    PubMed

    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

  14. Measurements of 210Pb and 7Be in China and their analysis accompanied with global model calculations of 210Pb

    NASA Astrophysics Data System (ADS)

    Lee, H. N.; Wan, Guojiang; Zheng, Xiangdong; Sanderson, Colin G.; Josse, Beatrice; Wang, Shilu; Yang, Wei; Tang, Jie; Wang, Changsheng

    2004-11-01

    Previous global models generally simulated high concentrations of 210Pb in the surface air over China. Measured data of 210Pb are needed in order to examine the accuracy and performance of the models. We collected the first-ever set of surface air radionuclide measurements of 210Pb and 7Be at Guiyang (26.57°N, 106.72°E, 1080 m above sea level) on the east of the Himalayas in Guizhou Province and at Mt. Waliguan (36.29°N, 100.90°E, 3816 m above sea level), a Global Atmosphere Watch station for the World Meteorological Organization, on the Qinghai-Tibetan plateau extending from the Himalayas in Qinghai Province, China. These measurements were carefully analyzed for data assurance and quality control and were used for validating models. The patterns for the variations in both measured 210Pb and 7Be at the Guiyang site have been shown to be consistent. In this case the increase of 7Be concentration was the result of the weak subsidence of air developed at the periphery of the high-pressure system. Because of the weak subsidence the boundary layer turbulence could mix the upward transport of 210Pb, thus increasing 210Pb concentration. The ratio of 7Be/210Pb indicated a seasonal variability with rough monthly oscillation. The ratio peaks were in spring and summer when the convective activities were significant. The 210Pb levels measured at Mt. Waliguan, located at the peak of the mountain, could be attributed to the long-range transport of 222Rn that decays to 210Pb, whereas the 7Be concentration varied directly with the local airflow passing over the site. We found that it was not appropriate to use the ratio of 7Be/210Pb for analysis of vertical transport exchange processes at the high-altitude Mt. Waliguan site because of the long-range transport of 210Pb that occurred at the site. For the purpose of model validation we have simulated the global transport of 210Pb for the year 2002 by using a comprehensive multiscale three-dimensional global chemical transport

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

    PubMed

    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

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

    PubMed

    Brown, J E; Gjelsvik, R; Roos, P; Kålås, J A; Outola, I; Holm, E

    2011-05-01

    Recent developments regarding environmental impact assessment methodologies for radioactivity have precipitated the need for information on levels of naturally occurring radionuclides within and transfer to wild flora and fauna. The objectives of this study were therefore to determine activity concentrations of the main dose forming radionuclides (210)Po and (210)Pb 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 exhibited an approximately exponential fall in (210)Pb activity concentrations from elevated levels in humus/surface soils to "supported" levels at depth. Activity concentrations of (210)Po in fauna (invertebrates, mammals, birds) ranged between 2 and 123 Bq kg(-1)d.w. and in plants and lichens between 20 and 138 Bq kg(-1)d.w. The results showed that soil humus is an important reservoir for (210)Po and (210)Pb and that fauna in close contact with this media may also exhibit elevated levels of (210)Po. Concentration ratios appear to have limited applicability with regards to prediction of activity concentrations of (210)Po in invertebrates and vertebrates. Biokinetic models may provide a tool to explore in a more mechanistic way the behaviour of (210)Po in this system. PMID:20650552

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

    PubMed

    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

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

    USGS Publications Warehouse

    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.

  19. A study on possible use of Urtica dioica (common nettle) plant as polonium (210)Po and lead (210)Pb contamination biomonitor in the area of phosphogypsum stockpile.

    PubMed

    Olszewski, Grzegorz; Boryło, Alicja; Skwarzec, Bogdan

    2016-04-01

    The aim of this study was to test a possible use of Urtica dioica (common nettle) plant as a biomonitor of polonium (210)Po and lead (210)Pb contamination near phosphogypsum stacks by determining concentrations of these radionuclides in samples collected from the area of phosphogypsum stockpile in Wiślinka (northern Poland). The (210)Po and (210)Pb contents in roots depended on their concentrations in soils. Bioconcentration factor values from soil to root of the plant did not depend on (210)Po and (210)Pb contents in soils that leads to the conclusion that different polonium and lead species have different affinities to U. dioica plants. The main sources of both analyzed radionuclides in green parts of plants are wet and dry air deposition and transportation from soil. The values of (210)Po/(210)Pb activity ratio indicate natural origin of these radioisotopes in analyzed plants. (210)Po and (210)Pb concentration in U. dioica roots is negatively weakly correlated with distance from phosphogypsum stockpile. PMID:26645235

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

    PubMed

    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

  1. 210Pb method for estimating the rate of carbonate sand sedimentation

    USGS Publications Warehouse

    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.

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

    PubMed

    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

  3. Geochemistry of /sup 210/Pb in the southeastern, US estuarine system

    SciTech Connect

    Storti, F.W.

    1980-11-01

    This study was an attempt to determine the geochemical behavior of /sup 210/Pb in southeastern salt marsh estuaries. As a part of this study the /sup 210/Pb dating technique was applied to natural and anthropogenic deposits of the region. /sup 210/Pb 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 /sup 210/Pb concentrations was evaluated and the activity of /sup 210/Pb 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. /sup 210/Pb 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 /sup 210/Pb activity in salt marsh sediments and grain size was highly significant. Direct application of the /sup 210/Pb 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 /sup 210/Pb activities to grain size (% silt and clay) and carbon content (% carbon).

  4. Skeletal sup 210 Pb from inhalation of sup 222 Rn and its decay products

    SciTech Connect

    Keane, A.T.; Schlenker, R.A.; Stebbings, J.H.

    1990-01-01

    Concern about health effects of radon and its decay products has recently broadened to include the potential role of radon in the causation of myeloid leukemia, multiple myeloma, and melanoma, kidney cancer, and certain childhood cancers. Description of the distribution of radon and its daughters in the skeleton and the marrow, and the dose delivered to red marrow, are of particular relevance. Our interest in a metabolic model for inhaled radon and radon decay products originated with an interest in the use of radioactivity measurement techniques in vivo to quantify the {sup 210}Pb activity of bone. In this paper we estimate the rates of transfer to body fluids of {sup 210}Pb originating from inhaled radon and radon decay products and the quantity of {sup 210}Pb deposited in compact and in cancellous bone for the ideal case of continuous exposure to a constant level of radon and its daughters. We review the contributions of ambient airborne {sup 210}Pb, diet, and active and passive smoking to skeletal levels of {sup 210}Pb, and finally, from the magnitude and the variability of the natural {sup 210}Pb content of the skeleton, we estimate the minimal rate of exposure to airborne radon and its decay products that is required to elevate the skeletal {sup 210}Pb content of an individual to a statistically significant level above the population mean skeletal {sup 210}Pb content derived from all the other environmental sources combined. 55 refs., 4 tabs.

  5. {sup 210}Po and {sup 210}Pb intake by the Portuguese population: The contribution of seafood in the dietary intake of {sup 210}Po and {sup 210}Pb

    SciTech Connect

    Carvalho, F.P.

    1995-10-01

    Through analysis of {sup 210}Po and {sup 210}Pb in the diet, the average ingestion rate for the Portuguese population is estimated at 1.2 and 0.47 Bq d{sup -1} per capita for {sup 210}Po and {sup 210}Pb, respectively. Detailed analysis of foods indicate that seafood alone contributes up to 70% of the {sup 210}Po ingestion rate, whereas cerals, vegetables, and meat altogether contribute 79% of the {sup 210}Pb ingestion rate. Consumption of seafood, both in terms of quantities (kg d{sup -1} per person) and preferential consumption of certain marine species, is the cause of the relatively high intake of {sup 210}Po and high {sup 210}Po:{sup 210}Pb ratio in the diet in comparison with other countries. Other {sup 210}Po and {sup 210}Pb sources, namely inhalation of surface air and cigarette smoke, contribute only a small percentage of the adsorption of these radionuclides in the blood. Estimated total body burdens of {sup 210}Po and {sup 210}Pb in adult men, 70 Bq, are 3.5 times higher than estimates for humans living in normal radioactivity regions and consuming a reference diet. Average whole body effective doses for the adult from the Portuguese population are estimated at about 85 {mu}Sv y{sup -1} from {sup 210}Po and 170 {mu}Sv y{sup -1} from {sup 210}Pb adsorbed with the diet. Effective dose from {sup 210}Po in the diet may vary from 25 {mu}Sv y{sup -1} in an heavy consumer of sardines, to 1,000 {mu}Sv y{sup -1} in an hypothetical heavy consumer of molluscs. 46 refs., 2 figs., 4 tabs.

  6. Spatial and temporal variability of (7)Be and (210)Pb wet deposition during four successive monsoon storms in a catchment of northern Laos.

    PubMed

    Gourdin, E; Evrard, O; Huon, S; Reyss, J-L; Ribolzi, O; Bariac, T; Sengtaheuanghoung, O; Ayrault, S

    2014-10-01

    Fallout radionuclides (7)Be and (210)Pb have been identified as potentially relevant temporal tracers for studying soil particles dynamics (surface vs. subsurface sources contribution; remobilization of in-channel sediment) during erosive events in river catchments. An increasing number of studies compared (7)Be: (210)Pb activity ratio in rainwater and sediment to estimate percentages of freshly eroded particles. However, the lack of data regarding the spatial and temporal variability of radionuclide wet deposition during individual storms has been identified as one of the main gaps in these estimates. In order to determine these key parameters, rainwater samples were collected at three stations during four storms that occurred at the beginning of the monsoon (June 2013) in the Houay Xon mountainous catchment in northern Laos. Rainwater (7)Be and (210)Pb activities measured using very low background hyperpure Germanium detectors ranged from 0.05 to 1.72 Bq L(-1) and 0.02 to 0.26 Bq L(-1), respectively. Water δ(18)O were determined on the same samples. Total rainfall amount of the four sampled storms ranged from 4.8 to 26.4 mm (51 mm in total) at the time-fractionated collection point. Corresponding cumulative (7)Be and (210)Pb wet depositions during the sampling period were 17.6 and 2.9 Bq m(-2), respectively. The (7)Be: (210)Pb activity ratio varied (1) in space from 6 to 9 for daily deposition and (2) in time from 3 to 12 for samples successively collected. Intra-event evolution of rainwater (7)Be and (210)Pb activities as well as δ(18)O highlighted the progressive depletion of local infra-cloud atmosphere radionuclide stock with time (washout), which remains consistent with a Raleigh-type distillation process for water vapour. Intra-storm ratio increasing with time showed the increasing contribution of rainout scavenging. Implications of such variability for soil particle labelling and erosion studies are briefly discussed and recommendations are formulated

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

    PubMed

    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

  8. Relationships Between Pb and 210Pb in Aerosol and Precipitation at a Semiremote Site in Northern Wisconsin

    NASA Astrophysics Data System (ADS)

    Talbot, R. W.; Andren, A. W.

    1983-08-01

    Measurements of Al, Pb, 210Pb, and 210Po in precipitation and aerosol were used to estimate wet and dry components of the atmospheric flux at a semiremote site in northern Wisconsin. Wet deposition was primarily responsible for removing airborne Pb, 210Pb, and 210Po, while dry deposition was also important for Al. Although Pb and 210Pb both exhibited a wet/total ratio of about 0.8, precipitation washout ratios for Pb and 210Pb suggested that 210Pb was washed from the atmosphere with greater efficiency than was Pb. This phenomenon was also illustrated by comparing the weighted mean annual specific activity in precipitation (976 pCi 210Pb mg-1 Pb) and in aerosol (476 pCi 210Pb mg-1 Pb) at this site between June 1979 and June 1980. By consideration of the apparent differential precipitation washout of Pb and 210Pb, a reasonable estimate of the atmospheric flux of Pb was obtained by using the mean Pb/210Pb ratio in aerosol and the 210Pb flux. The atmospheric flux to northern Wisconsin was estimated to be 0.8 μg cm-2 yr-1 for Pb and 0.70 pCi cm-2 yr-1 for 210Pb.

  9. Determination of (210)Pb and (210)Po in water using the extractive scintillation cocktail Polex™.

    PubMed

    Landstetter, Claudia; Hiegesberger, Bernd; Sinojmeri, Merita; Katzlberger, Christian

    2014-11-01

    Method validation was performed to achieve the accreditation for our determination method of (210)Pb and (210)Po in water. A Pb(NO3)2 carrier is added to the sample and lead is precipitated with Na2SxH2O. (210)Po is co-precipitated and the extractive scintillation cocktail Polex(™) is used to determine (210)Po and (210)Pb. Uranium is also extracted by Polex(™). It can be removed by washing the precipitate with 1% HNO3. The ingrowth of (210)Pb from (222)Rn during transportation time must be calculated. It has to be subtracted from the original (210)Pb in the sample and taken into account for the calculation of the lower limit of detection. PMID:24816175

  10. 210Po and 210Pb inhalation by cigarette smoking in Italy.

    PubMed

    Desideri, Donatella; Meli, Maria Assunta; Feduzi, Laura; Roselli, Carla

    2007-01-01

    210Po and its precursor 210Pb in cigarette smoke contribute a significant radiation dose to the lungs of smokers. In this work, the concentration of 210Po was determined in 17 of the most frequently smoked cigarette brands in Italy. Samples of tobacco, fresh filters, ash, and post-smoking filters were analyzed; 210Po was determined by alpha spectrometry after its spontaneous deposition on a silver disk. To verify the radioactive equilibrium between 210Po and 210Pb, lead was determined in one tobacco sample by counting the beta activity of its decay product 210Bi with a gas flow proportional detector after separation. The results of the present study show 210Po concentrations ranged from 6.84 to 17.49 mBq per cigarette. Based on these results, smokers who smoke 20 cigarettes per day inhale, on average, 79.53 +/- 28.65 mBq d(-1) of 210Po and 210Pb each. The mean value of the annual committed effective dose for Italian smokers, calculated by applying the dose conversion factor for adults of 4.3 microSv Bq(-1) for 210Po and 5.6 microSv Bq(-1) for 210Pb, was estimated to be 124.8 and 162.6 microSv y(-1) for 210Po and 210Pb, respectively. The lung dose from inhalation of cigarette smoke is much higher than the lung dose from inhalation of atmospheric 210Po and 210Pb. PMID:17164600

  11. Evidence for diffusive redistribution of sup 210 Pb in lake sediments

    SciTech Connect

    Benoit, G.; Hemond, H.F. )

    1991-07-01

    {sup 210}Pb, {sup 210}Po, and ancillary geochemical parameters were measured in the sediments and pore waters of a lake with seasonally anoxic bottom waters. Substantial release of radionuclides to the water column has been documented at this site. Solid phase {sup 210}Pb profiles do not match the expected input history, suggesting that the radionuclide may be undergoing redistribution. High levels of the radionuclides were measured in pore waters, consistent with partition coefficients in the range from 10{sup 3} to 10{sup 4}. The high pore water activities, apparent redistribution pattern, and the documented release of {sup 210}Pb from these sediments to the water column, all point to the possible importance of pore water diffusion as a {sup 210}Pb transport mechanism. The distribution of {sup 210}Pb in these sediments was successfully modeled using a combination of sediment burial and pore water diffusion without the need to invoke particle reworking. Theoretical analysis supports the idea that in some cases large dating errors can result if diffusive redistribution of {sup 210}Pb is neglected.

  12. Extreme 210Pb-226Ra Disequilibria Observed in arc Lavas: Implications for the Time Scales of Magma Degassing

    NASA Astrophysics Data System (ADS)

    Turner, S.; Black, S.

    2003-12-01

    We have undertaken α -counting measurements of 210Pb activity in 39 arc lavas previously analysed by TIMS for U-Th-Ra and, more recently, U-Pa disequilibria from the Lesser Antilles, Tonga, Vanuatu, Philippines, Marianas, Sunda, Kamchatka and the Aleutians. The lavas were erupted between 1953 and 1999 and show extreme variation in 210Pb -226Ra disequilibria with age corrected (210Pb /226Ra) activity ratios ranging from 0.36 to 3.14. In detail, the majority (25) of the lavas analysed preserve 210Pb deficits with 17 having (210Pb /226Ra) < 0.9 and 7 (210Pb /226Ra) < 0.8 whilst 5 are below (210Pb /226Ra) = 0.6. Of the 14 lavas that have 210Pb excess, 6 have (210Pb /226Ra) > 1.2. Whereas 210Pb deficits are found across the compositional spectrum of lavas analysed (silica = 47-65 percent), (210Pb /226Ra) appears to increase with increasing silica in those lavas that have 210Pb excesses. The 210Pb deficits are most readily interpreted in terms of protracted magma degassing and the numerical model of Gauthier and Condomines 1999 (EPSL 172: 111-126) suggests that the typical duration of degassing is on the order of 10's of years but may reach 45 years in the case of the largest 210Pb deficits at Yasur in Vanuatu, Mt Mayon in the Philippines, Avachinsky in Kamchatka and Spurr, Redoubt and Shishaldin in the Aleutians. These estimates for the duration of degassing represent minimum time scales since they assume 100 percent efficient degassing of 222Rn and no magma replenishment during that period. Therefore, it appears that the majority of arc magmas undergo efficient and protracted degassing for decades prior to eruption. By contrast, there is no simple model for explaining the 210Pb excesses. Mass balance calculations indicate that plagioclase accumulation cannot account for the observed excesses. Instead, we suggest that inefficient gas release and/or sublimation of 210Pb produced by decay from 222Rn during gaseous transport through the magma may be responsible for the

  13. Meso and small-scale variations of 210Pb fluxes on the Northwestern Mediterranean continental margins

    NASA Astrophysics Data System (ADS)

    Radakovitch, O.; Sanchez-Cabeza, J. A.; Abassi, A.; Masqué, P.; Heussner, S.

    2003-05-01

    210Pb was analysed in samples collected from (16) sediment traps, deployed during 1 year on the Northwestern Mediterranean continental margins, within the framework of the (MTP I)-EUROMARGE-NB programme. The traps were moored within (5) submarine canyons and their adjacent open slope, corresponding to contrasting conditions of particle inputs (fluxes and constituents). The major meso-scale observation (at the margin) is the variation in 210Pb fluxes along the slope, increasing by a factor of 2-3 between the entrance and the exit of the slope, in relation to the general (water) circulation. At a smaller scale (canyon), the 210Pb fluxes showed trends which were common to the various sites, i.e. a seaward decrease at 500 m depth and an increase, with depth, in the canyons. All these features are related to mass flux variations, except for periods with huge mass fluxes, when 210Pb fluxes reached a constant value. 210Pb activities decreased with increasing mass flux; then did not show clear relationship with the concentration of the major constituents of the flux. 210Pb fluxes, obtained from the traps were mainly in excess of the theoretical 210Pb flux, available in the overlying water column. Since 210Pb inventories, measured on the basis of the shelf and slope bottom sediments, were also in excess in relation to the available flux. The margin, as a whole, appears as a sink for 210Pb. This boundary-scavenging process appears to be controlled completely by the mass flux of particles. Differences were observed between 210Pb fluxes in the near-bottom traps and in the underlying sediments; there can be linked to mass flux and/or morphobathymetry (the trap flux is higher than the sediment flux in the canyon, but lower on the open slope). Overall, the differences were not in excess of 50%, confirming good representation of data collected by the sediment traps. However, this finding must be taken into account when comparing organic carbon or other constituent fluxes, between

  14. Decay/ingrowth uncertainty correction of (210)Po/(210)Pb in seawater.

    PubMed

    Lin, Wuhui; Ma, Hao; Chen, Liqi; Zeng, Zhi; He, Jianhua; Zeng, Shi

    2014-11-01

    Due to increasing application of (210)Po/(210)Pb in studying particle dynamics, a consistent procedure and calculation to derive accurate and precise result of (210)Po and (210)Pb 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 (210)Pb activity was independent of elapsed time and equal to relative uncertainty of laboratory measuring (210)Po activity at second spontaneous deposition date. The relative uncertainty of in-situ (210)Po activity decreases with in-situ activity ratio of (210)Po to (210)Pb and increases with elapsed time between sampling date and separation date, relative uncertainty of laboratory measuring (210)Po activity at first spontaneous deposition date and relative uncertainty of in-situ (210)Pb activity. It was more important to improve precision of (210)Po at first spontaneous deposition date than that of (210)Po at second spontaneous deposition date. To obtain a desirable relative uncertainty of in-situ (210)Po activity, the maximum allowing elapsed time for (210)Po, which was important for sampling strategy making and quality assurance, was calculated by in-situ activity ratio of (210)Po to (210)Pb and precision of analytical method for (210)Po. The methodology of decay/ingrowth uncertainty correction could also be applied for other radionuclide pairs ((234)Th/(238)U, (90)Y/(90)Sr, (210)Bi/(210)Pb), sample matrixes (aerosols), and disciplines. PMID:24992240

  15. Influence of submarine groundwater discharge on (210)Po and (210)Pb bioaccumulation in fish tissues.

    PubMed

    Garcia-Orellana, J; López-Castillo, E; Casacuberta, N; Rodellas, V; Masqué, P; Carmona-Catot, G; Vilarrasa, M; García-Berthou, E

    2016-05-01

    This study presents the results of the accumulation of (210)Po and (210)Pb in fish tissues and organs in a brackish-water marshland that is characterized by high concentrations of (222)Rn and (226)Ra supplied by submarine groundwater discharge (SGD). Tissues and organs from Cyprinus carpio, Chelon labrosus and Carassius auratus in the wetland were significantly enriched by both (210)Pb and (210)Po (up to 55 and 66 times, respectively) compared to blanks. The major input route of (210)Pb and (210)Po into the fish body seems to be through ingestion, due to the high levels of (210)Pb and (210)Po found in the gut content as well as in organs involved in digestion and metabolism (i.e. gut, kidney and hepatopancreas). Results showed that (210)Po was more accumulated in all fish tissues and organs except for the spine, which showed a higher affinity for (210)Pb, due to its capacity to replace Ca from apatite in bones. Over all the variables analyzed, fish tissues/organs and, secondarily, fish species were the most important factors explaining the concentration of radionuclides, whereas fish length and the sampling location played a minor role. The relationship of the two radionuclides varied markedly among tissues and their concentration levels were only correlated in gills, gut and, marginally, in spines. In general, the highest values of (210)Pb and (210)Po concentrations in tissues were found on C. labrosus tissues rather C. auratus and C. carpio. This study demonstrates that inputs of natural radionuclides supplied by SGD to coastal semi-enclosed areas (such as marshlands, lagoons or ponds) may significantly increase the contents of (210)Pb and (210)Po in fish tissues/organs. Thus, this study represents one of the first evidences of direct ecological effects derived from SGD. PMID:26913976

  16. [Alpha-spectroscopic determination of 210Pb and 210PO in snow samples].

    PubMed

    Hashimoto, T; Masumura, S; Komatsu, S; Sotobayashi, T

    1982-09-01

    The concentrations of 210Pb and 210PO in several snow samples were determined using alpha-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 alpha-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. PMID:7156418

  17. Detection of /sup 210/Pb in the lungs of smokers by in-vivo gamma spectrometry

    SciTech Connect

    Berger, C.D.; Lane, B.H.

    1982-09-01

    Since mainstream smoke is highly enriched in /sup 210/Pb, alpha radiation from inhaled cigarette smoke particles has been proposed as a cancer-producing agent in cigarette smokers. /sup 210/Po and /sup 210/Pb have been observed in tobacco, cigarette smoke and in the lungs of smokers. Since /sup 210/Pb is highly enriched in mainstream smoke, there have been estimates of yearly excesses of /sup 210/Pb 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 /sup 210/Pb in the lungs of smokers over those of non-smokers. Sources of error are also discussed.

  18. Determination of 210Pb and 222Rn in ground water of Okinawa Island

    NASA Astrophysics Data System (ADS)

    Ito, M.; Tanahara, A.

    2012-12-01

    In this study, we developed the method of 210Pb measurement from a large amount of ground water. The chelating resin (NOBIAS CHELATE-PA1; Hitachi High-technology) column combined with the ion-exchange resin (DOWEX-88; Dow Chemical Company) column were used for pre-treatment of 210Pb from ground water of 20 litter. It should be mentioned that this determination procedure is simple, fast, and give high recovery (more than 80 %). It avoids precipitation and large consumption of chemicals. Finally 210Pb was precipitated as PbSO4 and determined with low background 2πgas flow counter. 210Pb concentration in ground water of Okinawa Island ranged from 1.40-16.7 mBq/L. We also found that the organo-210Pb complex which could not be detected by this method was involved in some water samples. By increasing the column radius and the resin mass, while keeping a constant height of the resin column, it is possible to additionally increase the flow rate and accelerate the isolation procedure. 222Rn was determined by the direct method. The emulsion scintillation cocktail (10 mL) and water sample (10 mL) were put into a vial. After shaking and stand for 200 min, 222Rn was counted by LSC for 120 min. 222Rn concentration in ground water of Okinawa Island ranged from 0.71-14.0 Bq/L.

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

    PubMed

    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

  20. Metrological Determination of Natural Radioactive Isotopes {sup 226}Ra, {sup 228}Ra and {sup 210}Pb by Means of Ge Detector

    SciTech Connect

    Almeida, Maria Candida M. de; Delgado, Jose U.; Poledna, Roberto; Oliveira, Estela Maria de; Silva, Ronaldo L. da

    2008-08-07

    A metrological method to determine the activity per mass unity (activity concentration) of {sup 226}Ra and {sup 210}Pb ({sup 238}U decay series) and {sup 228}Ra ({sup 232}Th series) by gamma-ray spectrometers based on hyper-pure coaxial germanium detector was developed. In the soil the {sup 22}Ra (half-life = 1600 years) exhibits the same level of radioactivity as {sup 238}U (half-life 4.5x10{sup 9} years) because of a natural phenomenon called secular equilibrium. {sup 226}Ra decays into {sup 222}Rn (half-life = 3.8 days), a radioactive inert gas. After several days, the {sup 222}Rn naturally decays to {sup 218}Po (half-life = 3 minutes), where finally {sup 210}Pb (half-life = 22 years) is produced. The metrological capability of high-resolution gamma-ray spectrometry for naturally occurring radionuclides at environmental levels is showed, with emphasis on the use of 2 mL standard sources volume in a glass ampoule. Source preparation and calibration procedures are described. Radionuclide standards in an activity range of 10 to 250 Bq/g were produced which can be applied in a variety of environmental sample analysis (water, plant material, sediment, etc.). Uncertainties for {sup 226}Ra and {sup 210}Pb around 3% (k = 1) were obtained.

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

    NASA Astrophysics Data System (ADS)

    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).

  2. Rapid determination of (210)Pb and (210)Po in water and application to marine samples.

    PubMed

    Villa-Alfageme, M; Mas, J L; Hurtado-Bermudez, S; Masqué, P

    2016-11-01

    Measurement of radionuclides in marine samples, specifically radioactive pairs disequilibrium, has gained interest lately due to their ability to trace cutting edge biogeochemical processes. In this context, we developed a fast, direct method for determining (210)Pb and (210)Po water through the use of ultra low-level liquid scintillation counting and alpha-particle spectrometry respectively and through Eichrom Sr resins for the Po-Pb separation. For (210)Pb analysis, the method uses stable lead as a yield tracer measured by a robust ICP-MS technique, and (210)Po is determined through self-deposition using the conventional (209)Po yield tracer. The improvements of the method over other techniques are: a) the analysis can be completed within 6 days, simplifying other methods, b) very low limits of detection have been achieved -0.12 and 0.005mBqL(-1) for (210)Pb and (210)Po, respectively - and c) most of the method could be carried out in on-board analysis. We applied the method to different aqueous samples and specifically to marine samples. We determined (210)Pb and (210)Po in the dissolved fraction of Mediterranean Sea water and an estuary at the South-West of Spain. We found that it can be successfully employed to marine samples but we recommend to i) use a minimum of 20L water to measure the (210)Pb in the dissolved phase by LSC and lower volumes to measure total concentrations; ii) wait for (210)Pb and (210)Bi in secular equilibrium and measure the total spectrum to minimise the limit of detection and improve accuracy. PMID:27591584

  3. Measurement of liquid scintillation sources of (210)Pb obtained from (222)Rn decay.

    PubMed

    Antohe, A; Sahagia, M; Luca, A; Ioan, M-R; Ivan, C

    2016-03-01

    Liquid scintillation samples were filled with (222)Rn and the activity was measured with good precision after reaching the secular equilibrium with the progeny (218)Po, (214)Pb, (214)Bi and (214)Po. After decay of most of (222)Rn activity, the samples contain (210)Pb and progeny. The activities of (210)Pb and progeny can be calculated as a function of time using the initial (222)Rn activity. The samples were measured in a TDCR counter and the experimentally determined counting efficiencies are in accordance with previously published results. PMID:26725538

  4. Distribution of 7Be, 210Pb and 137Cs in watersheds of different scales in the Seine River basin: inventories and residence times.

    PubMed

    Le Cloarec, Marie-Françoise; Bonté, Philippe; Lefèvre, Irène; Mouchel, Jean-Marie; Colbert, Steven

    2007-04-01

    The activity of environmental radionuclides ((7)Be, (210)Pb and (137)Cs) was monitored in nested catchments, inside the Seine River basin. Suspended matter data was collected at 8 different watersheds, ranging from order 1 to order 7, and ranging in size over 4 orders of magnitude. Suspended matter was analyzed for (210)Pb, (137)Cs and (7)Be, and used to calculate the flux of sediments out of each watershed. Monthly atmospheric flux data of (210)Pb and (7)Be was analyzed to assess the input flux of each into the watersheds, taking into account the rainfall during sampling periods. Taking advantage of the different half-lives of (7)Be (53 days) and (210)Pb (22 years), a two-box model was built for each of the catchments following a methodology previously developed by Dominik et al. [Dominik J, Burrus D, Vernet JP. Transport of the environmental radionuclides in alpine watershed. Earth Planet Sci Letters 1987; 84: 165-180.]. The model divides the watershed into a soil box and a rapid reservoir and provides insight into the removal rate of suspended matter from the surrounding watershed. The model enables the assessment of the surface area and the residence time of slow and rapid reservoirs to describe the fate of contaminants of atmospheric origin inside the river basin. The model was improved by considering the dissolved fraction in the total flux and adding the (137)Cs inventory as an additional constraint. The effects of these changes are discussed. Residence times in the soil box, characterized by low transport velocity, range between 4800 years at Melarchez (order 1) to about 30000 years at Andresy and Poses (order 7). They remain constant in each watershed over a large range of variation of atmospheric fluxes of (7)Be and (210)Pb during the whole study, but are sensitive to SM variations. The residence time in the rapid box, which includes the surface of the river and immediate surroundings, is less than one year, while its surface area is in the range 0.6% to

  5. RELATIONSHIPS BETWEEN PB AND 210 PB IN AEROSOL AND PRECIPITATION AT A SEMIREMOTE SITE IN NORTHERN WISCONSIN

    EPA Science Inventory

    Measurements of Al, Pb, (210)Pb, and (210)Po in precipitation and aerosol were used to estimate wet and dry components of the atmospheric flux at a semiremote site in northern Wisconsin. Wet deposition was primarily responsible for removing airborne Pb, (210)Pb, and (210)Po, whil...

  6. Lead precipitation fluxes at tropical oceanic sites determined from /sup 210/Pb measurements

    SciTech Connect

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

    1982-02-20

    Concentrations of lead, /sup 210/Pb, and /sup 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 /sup 210/Pb in rain were 250--900 for Pigeon Key (assuming 12% adsorption for /sup 210/Pb 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 /sup 210/Pb precipitation fluxes, are about 4 ng Pb/cm/sup 2/y for Tahiti, 10 for Enewetak, and 270 for the Sargasso Sea site, and between 110 to 390 at Pigeon Key.

  7. Growth rate of a deep-sea coral using sup 210 Pb and other isotopes

    SciTech Connect

    Druffel, E.R.M.; King, L.I.; Belastock, R.A.; Buesseler, K.O. )

    1990-05-01

    A deep-sea coral was studied to determine its growth rate and to reconstruct time histories of isotope distributions in the deep ocean. The specimen was collected at a depth of 600 m off Little Bahama Banks using the Deep Submergence Vehicle (DSV) Alvin. The growth rate of the calcitic coral trunk was determined using excess {sup 210}Pb measured in concentric bands. Excess {sup 210}Pb was found in the outer half of the coral's radius, and a growth rate of 0.11 {plus minus} 0.02 mm/a is calculated. Assuming a constant growth rate during formation of the entire trunk, an age of 180 {plus minus} 40 a is estimated for the coral. The decrease observed in radiocarbon activities measured on the same bands (Griffin and Druffel, 1989) concurred with the growth rate estimated from excess {sup 210}Pb activity. {sup 239,240}Pu activities measured by mass spectrometry were also detected in the outer two bands of the coral, as expected from the {sup 210}Pb chronology. Stable oxygen and carbon isotopes measured in samples collected by a variety of techniques are positively correlated. This is evidence of a variable kinetic isotope effect most likely caused by variations in the skeletal growth rate. Long-lived corals such as this specimen have the potential for serving as integrators of seawater chemistry in the deep-sea over several century timescales.

  8. /sup 210/Pb dating and the recent geologic history of Crystal Bay, Lake Minnetonka, Minnesota

    SciTech Connect

    Murchie, S.L.

    1985-11-01

    /sup 210/Pb dating of five cores from Crystal Bay, Lake Minnetonka, was used to examine the geologic history of the basin during the last century. A lakewide /sup 210/Pb budget and the basinwide average cumulative activities of /sup 210/Pb within time-stratigraphic units were estimated from multiple cores. Ages of time-stratigraphic markers and sediment accumulation rates of time-stratigraphic units were calculated from a constant-flux /sup 210/Pb-dating model. The basinwide bulk-sediment accumulation rate was found to have increased from 0.003 g cm/sup -2/ yr/sup -1/ before settlement to 0.07 g cm/sup -2/ yr/sup -1/ for the period from 1962 to 1983. Since settlement of the surrounding area, profundal sediment became highly calcareous and accumulation of littoral marl began. Intensity of focusing of sediment to the center of Crystal Bay decreased as basinwide sediment accumulation rates increased. Light organic sediment was also found to be more intensely focused than heavier siliceous or calcareous sediment. Accumulation of sediment spread to regions shallower than 5 m as the rate of sedimentation exceeded the rate of sediment resuspension at the depth, about 4 mm yr/sup -1/.

  9. Distribution of 7Be, 210Pb and 210Po in Size Fractionated Aerosols From Northern Taiwan

    NASA Astrophysics Data System (ADS)

    Su, C.; Huh, C.

    2003-12-01

    The partition of 7Be, 210Pb and 210Po in size fractionated aerosols was studied using samples collected from Nankang (northern Taiwan) during July 2002-July 2003. A TSP air sampler coupled to a 6-stage cascade impactor was used to collect large-volume samples and separate the aerosols into six size classes with the cut-off points at 7.2 μ m, 3 μ m, 1.5 μ m, 0.95 μ m and 0.49 μ m. The total mass concentrations of the aerosol samples ranged from 23 to 99 μ g m-3, with a maximum (18-50 %) falling at the sixth stage (< 0.49 μ m) and a minimum (5-13 %) at the third stage (1.5-3.0 μ m). Total concentrations of 7Be, 210Pb and 210Po in the samples were 0.11-0.56, 0.012-0.100 and 0.0009-0.0158 dpm m-3, respectively. For most of the samples, more than 70 % of the radioactivities are found in the fifth and sixth stages (< 0.95 μ m). Concurrent with the measurements of 7Be and 210Pb concentrations in aerosols, we have also measured the fluxes of these nuclides. Coupling the concentration data with the flux data, we obtained an overall deposition velocity of 0.02-3.71 cm s-1 for 7Be and 0.09-6.18 cm s-1 for 210Pb, without any obvious seasonal variation during the experimental periods. The size of aerosol particles and the height of cloud are the major factors controlling the deposition velocity of 7Be and 210Pb. The time series of 210Po/210Pb was in phase with that of 7Be/210Pb and showed an increase during the spring and summer, probably reflecting stratospheric folding in the spring and more vigorous tropospheric mixing (e.g., due to typhoons) in the summer.

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

    PubMed

    Persson, Bertil R R; Holm, Elis

    2014-12-01

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

  11. Concentration levels of 210Pb and 210Po in dry tobacco leaves in Greece.

    PubMed

    Savidou, A; Kehagia, K; Eleftheriadis, K

    2006-01-01

    Tobacco leaves are large and have sticky exudates that retain the radon decay products once they deposit on the leaves. The study of 210Po in tobacco is required, because of the cumulative alpha-radiation dose delivered to humans from inhaled 210Po in cigarette smoke. 210Pb is the other element of interest since it is the 210Po precursor in the radioactive decay chain. In the present study, the concentrations of these two radionuclides were determined in tobacco samples from seven regions in Greece. 210Po was determined by alpha spectrometry using a surface barrier detector after radiochemical separation and spontaneous deposition of polonium on a nickel disk. The 210Pb activity in the samples was determined via the 210Po resulting from the decay of 210Pb. The results of the present study indicate that 210Po concentrations ranged from 3.6 to 17.0 mBqg(-1) (average 13.1 mBqg(-1)) of dry tobacco, while 210Pb concentrations ranged from 7.3 to 18.0 mBqg(-1) (average 13.4 mBqg(-1)). The mean value of the annual committed effective dose for smokers (20 cigarettes per day) of Greek tobacco was estimated to be 287 microSv (124 microSv from 210Po and 163 microSv from 210Pb). The inhalation dose for smokers is on average about 12 times higher than for non-smokers living in the mid-latitudes of the northern hemisphere. PMID:16098642

  12. Atmospheric flux, transport and mass balance of (210)Pb and (137)Cs radiotracers in different regions of Romania.

    PubMed

    Begy, R Cs; Kovacs, T; Veres, D; Simon, H

    2016-05-01

    This study focuses on the determination of (210)Pb and (137)Cs fluxes from different areas in Transylvania, Romania and on the determination of transport and mass balance within the lacustrine system of Red Lake. In order to achieve this, samples were taken from six different locations (Bihor County area, Ighiel area, Red Lake area, Mluha Peatbog, Mohos Peatbog and Zanoaga Rosie Peat bog in the Semenic Mountains) throughout Romania, these being compared to the values of the Danube Delta area. The activity concentrations of the soil samples were measured by gamma spectrometry (HPGe detector) for both (210)Pbtotal, (210)Pbsup ((226)Ra) and (137)Cs, while peat samples were measured by both alpha ((210)Po) spectrometry (PIPS detectors) as well. The mean value for the (210)Pb flux was measured in the Danube Delta region (42±8Bqm(-2) yr(-1)), while the highest was measured in the Semenic Peatbog (227±54Bqm(-2) yr(-1)); the average being 132±8Bqm(-2) yr(-1). In case of (137)Cs the mean was 298±3Bqm(-2) yr(-1), maximum being 1683±15Bqm(-2) yr(-1) in case of Ighiel area and minimum being 32±1Bqm(-2) yr(-1) in the Danube Delta region. In case of the Red Lake, from the total inventory of 410±23Bqm(-2) yr(-1) in the sediments, the loss by outflows is 100±12Bqm(-2) yr(-1), the catchment to lake transfer factor being 0.84%. PMID:26922393

  13. Tracing pre-eruptive magma degassing using ( 210Pb/ 226Ra) disequilibria in the volcanic deposits of the 1980-1986 eruption of Mount St. Helens

    NASA Astrophysics Data System (ADS)

    Berlo, Kim; Turner, Simon; Blundy, Jon; Black, Stuart; Hawkesworth, Chris

    2006-09-01

    Disequilibria between 210Pb and 226Ra can be used to trace magma degassing, because the intermediate nuclides, particularly 222Rn, are volatile. Products of the 1980-1986 eruptions of Mount St. Helens have been analysed for ( 210Pb/ 226Ra). Both excesses and deficits of 210Pb are encountered suggesting rapid gas transfer. The time scale of diffuse, non-eruptive gas escape prior to 1980 as documented by 210Pb deficits is on the order of a decade using the model developed by Gauthier and Condomines (Earth Planet. Sci. Lett. 172 (1999) 111-126) for a non-renewed magma chamber and efficient Rn removal. The time required to build-up 210Pb excess is much shorter (months) as can be observed from steady increases of ( 210Pb/ 226Ra) with time during 1980-1982. The formation of 210Pb excess requires both rapid gas transport through the magma and periodic blocking of gas escape routes. Superposed on this time trend is the natural variability of ( 210Pb/ 226Ra) in a single eruption caused by tapping magma from various depths. The two time scales of gas transport, to create both 210Pb deficits and 210Pb excesses, cannot be reconciled in a single event. Rather 210Pb deficits are associated with pre-eruptive diffuse degassing, while 210Pb excesses document the more vigorous degassing associated with eruption and recharge of the system.

  14. Transfer of {sup 210}Po and {sup 210}Pb through the lichen-caribou-wolf food chain of northern Canada

    SciTech Connect

    Thomas, P.A.; Sheard, J.W.; Swanson, S.

    1994-06-01

    Natural background activity and food chain transfer of the uranium decay products, {sup 210}Po and {sup 210}Pb, were examined in the lichen-caribou-wolf food chain at two locations in the Northwest Territories of Canada. {sup 210}Po and {sup 210}Pb activities in lichens differed with species and location. Both {sup 210}Po and {sup 210}Pb were markedly higher in caribou bone than in wolf bone. {sup 210}Po activities in liver, kidney, and muscle were similar in both species. Caribou fetuses had lower activities of {sup 210}Po but higher activities of {sup 210}Pb than maternal muscle and placenta, suggesting greater placental transport of {sup 210}Pb than {sup 210}Po. Concentration ratios (CR = Bq kg{sup {minus}1} in consumer/Bq kg{sup {minus}1} in its food source) and f{sub f} values (f{sub f} in d kg{sup {minus}1} = Bq kg{sup {minus}1} in muscle/Bq d{sup {minus}1} ingested) showed that wolves retain more {sup 210}Po and less {sup 210}Pb from their diet than do caribou. {sup 210}Po CRs averaged 0.38 for caribou/lichens, 0.26 for caribou/rumen contents, and 0.40 for wolves/caribou. {sup 210}Pb CRs averaged 0.36 for caribou/lichens, 0.57 for caribou/rumen contents, and 0.13 for wolves/caribou. 43 refs., 4 figs., 5 tabs.

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

    PubMed

    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

  16. 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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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

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

    PubMed

    Bonotto, Daniel Marcos; Vergotti, Marcelo

    2015-05-01

    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 350km sector of the river. The (21)(0)Pb 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 (21)(0)Pb 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 (21)(0)Pb 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 (21)(0)Pb-method in the studied lakes, whereas the CF:CS model predicted two values above 140 years. PMID:25699663

  19. Atmospheric 210Pb and anthropogenic trace metals in the continental outflow to the Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Bikkina, Srinivas; Sarin, M. M.; Chinni, Venkatesh

    2015-12-01

    Atmospheric 210Pb and trace metals (Pb, Cd, Cu, Mn, Cr, Co, Ni and Zn) have been studied in fine mode aerosols (PM2.5) from a sampling site (Kharagpur: 22.3°N, 87.3°E) in the Indo-Gangetic Plain (IGP) during the continental outflow (November-March) to the Bay of Bengal (BoB). The aerosol 210Pb activity (1.3-6.6 mBq m-3) is significantly high in the wintertime (December-January) compared to model based data in the literature. The cause for higher 210Pb activity is attributed to enhanced 222Rn emanation from Alluvium in the IGP as well as lower boundary layer height. The trace metal concentrations (in ng m-3) also exhibit pronounced temporal variability (Pb: 8-296, Mn: 8-568, Cr: 4.5-33, Cu: 2.1-29.3, Ni: 2.3-14.3, Co: 0.5-1.6 and Cd: 1-29.5) and are of comparable magnitude with those documented over the BoB (Srinivas and Sarin, 2013b), suggesting dominant impact of IGP-outflow on marine atmospheric boundary layer. The enrichment factors (EFcrust) of Pb, Cd, Cu, Mn, Cr, Co and Ni in PM2.5, relative to upper continental crust, varied as 105-1561, 1265-24006, 13-87, 3-99, 7-27, 3-19 and 9-27, respectively. Significant linear relationship among trace metals and chemical species (non-sea-salt-K+, nss-SO42- and EC) emphasizes their anthropogenic source. The high concentrations and EFcrust of Pb, Cd and Cu, together with residence time of PM2.5 (2-13 days, assessed from 210Pb) in the IGP-outflow has implications to increase in the aerosol toxicity and their impact on biogeochemistry of ocean surface waters via air-sea deposition.

  20. A method for simultaneous determination of 210Pb and 212Pb in drinking water samples

    NASA Astrophysics Data System (ADS)

    Jia, Guogang; Torri, G.; Leandro, M.

    2012-04-01

    A sensitive and accurate method for determination of 210Pb and 212Pb in drinking water samples was developed. In the method Pb was pre-concentrated as hydroxides, separated from alkaline earth elements as PbS precipitate, purified by an anion exchange resin chro-matography column, precipitated as PbSC4 for source preparation and counted by a low background β-counter. The procedure was checked with a reference material supplied by the IAEA, and the obtained data were in good agreement with the recommended values, showing the recommended procedure can provide reliable results. The minimum detectable activity of the method was 0.039 mBq L-1 for 210Pb and 0.033 mBq L-1 for 212Pb if a 48 liter of water sample was analyzed. Seventeen drinking water samples were analyzed with a Pb recovery of 88.8 ± 5.5%, and the typical activity concentration was in the range of 0.191-15.1 mBq L-1 for 210Pb and of 1.12-5.77 mBq L-1 for 212Pb.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    Peres, A C; Hiromoto, G

    2002-01-01

    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 1.5 x 10(4) man-Sv. PMID:12141603

  3. 210Pb and 210Po in fossil fuel combustion at the Šoštanj thermal power plant (Slovenia)

    NASA Astrophysics Data System (ADS)

    Vreček, P.; Benedik, L.

    2003-01-01

    The main aim of the present study was to evaluate 210Pb and 210Po emissions from the Šoštanj TPP and to evaluate their mass balance in unit 4. Samples of coal, fly ash, slag and flue gases were analysed for 210Pb and 210Po content. The results showed that these radionuclides are mostly concentrated in ash (71% and 81% for 210Pb and 210Po, respectively). Only a small part of the input activity was detected in flue gases. The activities of 210Pb and 210Po in unit 4 were from 1.1 to 2.7 Bq m-3 and from 0.37 to 0.56 Bq m-3, respectively. The mass balance of the two radionuclides in unit 4 show only 6 and 10% differences between the annual activities of the input and output samples.

  4. Degradation of nonylphenol in spiked soils and in soils treated with organic waste products.

    PubMed

    Mortensen, Gerda Krog; Kure, Liv Kerstin

    2003-04-01

    Widespread application of sewage sludge to agricultural soils in Denmark has led to concern about the accumulation and effects of nonylphenol (NP) in the soil ecosystem. We have thus studied the degradation of NP and possible uptake in agricultural plants in greenhouse pot experiments. Different waste products including anaerobic and aerobic sludge, compost, and pig manure were incorporated into a sandy soil. In addition, NP was used to spike soil to known concentrations. Rape (Brassica napus L. cv Hyola 401) was sown in the pots and harvested after 30 d. In order to investigate the influence of plant growth on the degradation, plant-free pots were established. The concentrations in the soil were between 13 and 534 ppb dry weight. No plant uptake was observed above the detection limit at 100 ppb dry weight. When NP was added as waste to the soil, plant growth significantly stimulated the degradation. In experiments with anaerobic and aerobic sludge, respectively, 13 and 8.3% of NP remained in the soil from pots planted with rape compared with 26 and 18% in soil without plant growth. When NP was added as a spike to soil, the degradation was more complete and plant growth did not influence the degradation. Percentages of 2.2 and 1.8 were still in the soil at harvest for planted and plant-free pots, respectively. The degradation of NP was more extensive in sludge-amended soil compared with compost. PMID:12685703

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    Marsan, D; Rigaud, S; Church, T

    2014-12-01

    During the spring and summer months of 2012, (210)Po and (210)Pb 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 (210)Po and (210)Pb. Box models were applied using mass balance calculations to assess the nuclides residence times in each estuary. Only 60% of the dissolved (210)Po and 55% of the dissolved (210)Pb from the Delaware estuary were exported to coastal waters. A large fraction of soluble (210)Po and (210)Pb 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 (210)Po and (210)Pb, hypothesized to be subjected to redox cycling of manganese. The Delaware and Chesapeake estuary mean residence times for (210)Po differed significantly at 86 ± 7 and 126 ± 10 days respectively, while they were similar for (210)Pb (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. PMID:25239647

  8. Disequilibrium between [sup 226]Ra and supported [sup 210]Pb in a sediment core from a shallow Florida lake

    SciTech Connect

    Brenner, M.; Peplov, A.J.; Schelske, C.L. )

    1994-07-01

    [sup 210]Pb dating can be used to assign ages in lake sediment cores, calculate rates of sediment accumulation, and determine the timing of recent changes in lake-watershed ecosystems. We used low-background gamma counting to measure [sup 226]Ra and total [sup 210]Pb activity in a core from Lake Rowell, Florida. [sup 226]Ra activity was high and strongly variable throughout the core, even exceeding total [sup 210]Pb activity in recently deposited sediments. We traced one source of Ra-rich sediments to the only inflow, Alligator Creek, where stream-bottom deposits display disequilibrium between [sup 226]Ra and supported [sup 210]Pb. High and variable [sup 226]Ra activity in the Lake Rowell profile argues for direct estimates of in situ Ra in lake sediment cores from disturbed watersheds that have Ra-bearing bedrock. Isotopic disequilibrium between [sup 226]Ra and supported [sup 210]Pb makes it difficult to distinguish between supported and unsupported [sup 210]Pb activity throughout the Lake Rowell core and would require special assumptions and nonconventional dating models to establish age-depth relationships. 78 refs., 3 figs., 1 tab.

  9. 210Pb balance and implications for particle transport on the continental shelf, U.S. Middle Atlantic Bight

    USGS Publications Warehouse

    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. ?? 1994.

  10. Evaluation of spiking procedures for the introduction of poorly water soluble contaminants into soil

    SciTech Connect

    Reid, B.J.; Northcott, G.L.; Jones, K.C.; Semple, K.T.

    1998-10-15

    There is currently considerable interest in the fate and behavior of persistent organic pollutants (POPs) within the soil environment. Processes such as sorption, desorption, subsurface transport, and biodegradation have been the focus of much attention. The purpose of this study was to assess the suitability of various spiking procedures for the introduction of persistent organic pollutants (POPs) into soil environments. {sup 14}C-radiolabeled analogues of two representative polycyclic aromatic hydrocarbons (PAHs), phenanthrene (Phe), and benzo[a]pyrene (B[a]P), were introduced into soil using different spiking techniques, and the homogeneity of compound distribution in subsamples was assessed. It was established that under analogous spiking procedures dry soil could be spiked with greater homogeneity than wet soil. The procedure which gave the most homogeneous distribution of compound involved a single spiking/rehydration operation conducted on dry soil. Relative standard deviations of 2.40% for {sup 14}C-9-Phe and 3.65% for {sup 14}C-7-B[a]P were obtained for this procedure. An optimum procedure for the spiking of wet soil was established, giving relative standard deviations of 4.1% for {sup 14}C-9-Phe and 3.7% for {sup 14}C-7-B[a]P. This procedure employed a highly spiked wet soil inoculum to distribute the compound throughout the soil system. The influence of carrier solvent on microbial cell numbers determined as colony forming units was also evaluated and shown to have a dramatic negative impact at high volumes.

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

    PubMed

    Vaaramaa, Kaisa; Solatie, Dina; Aro, Lasse

    2009-12-15

    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. PMID:19800659

  12. The geochemistries of 210Po and 210Pb in waters overlying and within the Orca Basin, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Todd, James F.; Wong, George T. F.; Reid, David F.

    1986-10-01

    Vertical profiles of dissolved 210Po, 210Pb, and 226Ra were obtained from waters overlying and within the Orca Basin; an anoxic, hypersaline and virtually non-sulfide bearing basin in the Gulf of Mexico. The station had a depth of 2410 m. The seawater-brine interface was located at 2230 m. In oxic waters, near-surface (0-250 m) concentrations of dissolved 210Po and 210Pb ranged from 6 to 8 dpm/100 kg and decreased to about 3 dpm/100 kg at 740 m. Below this depth concentrations remained relatively constant. Near-surface 226Ra concentrations varied from about 7 to 9 dpm/100 kg, and then increased with depth to a relatively uniform deep-water value of approximately 13 dpm/100 kg, in agreement with previously reported data for the Gulf of Mexico. The slight deficiency of 210Pb in the surface waters may result from mixing with inner shelf waters that are enriched in 226Ra. At the seawater-brine interface, sharp maxima were observed in the profiles of 210Po, 210Pb, and 226Ra, where concentrations reached 56.0, 28.3, and 840 dpm/100 kg, respectively. These are among the highest values reported for the marine environment to date. Below the interface, concentrations decreased to about 9, 6, and 210 dpm/100 kg for 210Po, 210Pb, and 226Ra, respectively. These sharp maxima may be caused by a combination of the accumulation of particles in the strong pycnocline, the subsequent dissolution of particulate hydrous Mn and Fe oxides and hydroxides, and the decomposition of biogenic particulate material. The residence time of 210Pb in the brine is about one year, a value similar to that reported for the anoxic waters of the Cariaco Trench even though the concentration of 210Pb in that basin is much lower.

  13. 210Pb and 210Po concentrations in Italian cigarettes and effective dose evaluation.

    PubMed

    Taroni, Mattia; Zagà, Vincenzo; Bartolomei, Paolo; Gattavecchia, Enrico; Pacifici, Roberta; Zuccaro, Piergiorgio; Esposito, Massimo

    2014-09-01

    It has been known for a long time that cigarette tobacco contains naturally occurring radioactive nuclides such as 210Pb and 210Po. In this study, the concentrations of 210Pb and 210Po in the 10 most widely sold cigarette brands in Italy during the year 2010 were measured, and the effective dose to smokers has been calculated. The results of this study show that 210Pb concentration ranged from 11.6 to 20.0 mBq cig-1 with an arithmetic mean of 14.6 mBq cig-1, while the activity concentration of 210Po ranged from 13.1 to 19.0 mBq cig-1 with an arithmetic mean of 15.7 mBq cig-1, thus confirming previous results and showing that the radioactivity concentration was not reduced in the last few years. The annual effective dose for a typical smoker consuming 20 cigarettes per day ranged from an average of 55 μSv y-1 to about 81 μSv y-1. It is finally put in evidence the need to improve the knowledge about crucial data needed for accurate dose assessment deriving from the inhalation of both radioisotopes contained in the cigarettes, namely the dose conversion coefficients, which strongly depend on several parameters such as the inhalation speed through the mouth, the real fraction of radionuclide transferred from cigarette to mainstream smoke, the lung absorption behavior of the radioisotopes inhaled with mainstream smoke, and the AMAD of particles inhaled by smokers. PMID:25068956

  14. Comparisons of 210Pb and pollen methods for determining rates of estuarine sediment accumulation

    USGS Publications Warehouse

    Brush, G.S.; Martin, E.A.; DeFries, R.S.; Rice, C.A.

    1982-01-01

    Comparisons of sedimentation rates obtained by 210Pb and pollen analyses of 1-m cores collected throughout the Potomac Estuary show good agreement in the majority of cores that can be analyzed by both methods. Most of the discrepancy between the methods can be explained by the analytical precision of the 210Pb method and by the exactness with which time horizons can be identified and dated for the pollen method. X-radiographs of the cores and the distinctness of the pollen horizons preclude significant displacement by reworking and/or mixing of sediments. Differences between the methods are greatest where uncertainties exist in assigning a rate by one or both methods (i.e., 210Pb trends and/or "possible" horizon assignments). Both methods show the same relative rates, with greater sediment accumulation more common in the upper and middle estuary and less toward the mouth. The results indicate that geochronologic studies of estuarine sediments should be preceded by careful observation of sedimentary structures, preferably by X-radiography, to evaluate the extent of mixing of the sediments. Time horizons, whether paleontologic or isotopic, are generally blurred where mixing has occurred, precluding precise identification. Whenever possible, two methods should be used for dating sediments because a rate, albeit erroneous, can be obtained isotopically in sediments that are mixed; accurate sedimentation rates are also difficult to determine where the time boundary is a zone rather than a horizon, where the historical record does not provide a precise date for the pollen horizon, or where scouring has removed some of the sediment above a dated pollen horizon. ?? 1982.

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

    PubMed Central

    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) 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. PMID:22934091

  16. Transport and sediment accumulation of sup 210 Pb and sup 137 Cs in two southeast Alaskan fjords

    SciTech Connect

    Sugai, S.F. )

    1991-05-01

    Sediment profiles of {sup 210}Pb and {sup 137}Cs in cores collected at increasing distances form the heads of Smeaton Bay and Boca de Quadra fjords indicate that watersheds influence the inventories of radioisotopes present and that the steep topographies of the fjords enhance sediment redistribution. Episodic deposition of terrestrially derived sediment was responsible for roughly 50% of the {sup 137}Cs and 45% of the {sup 210}Pb inventories in shallower (less than 180 m) locations in Wilson and Bakewell arms of Smeaton Bay. {sup 210}Pb sedimentation rates at shallower sites when corrected for episodic deposition were less than sedimentation rates obtained in the deep basins of the fjords where sediment focusing and increased primary productivity in the overlaying water column occur. Higher fluxes of dissolved Mn from surficial sediments and subsequent reoxidation in the overlying water may have enhanced scavenging of {sup 210}Pb in basin locatons resulting in higher inventories. Episodic events have occured frequently in Smeaton Bay and Boca de Quadra suggesting that steady-state conditions with respect to sedimenting particles can be achieved only when averaged over long time periods approaching the time over which {sup 137}Cs and {sup 210}Pb are useful.

  17. Residence times of fine tropospheric aerosols as determined by {sup 210}Pb progeny.

    SciTech Connect

    Marley, N. A.; Gaffney, J. S.; Drayton, P. J.; Cunningham, M. M.; Mielcarek, C.; Ravelo, R.; Wagner, C.

    1999-10-05

    Fine tropospheric aerosols can play important roles in the radiative balance of the atmosphere. The fine aerosols can act directly to cool the atmosphere by scattering incoming solar radiation, as well as indirectly by serving as cloud condensation nuclei. Fine aerosols, particularly carbonaceous soots, can also warm the atmosphere by absorbing incoming solar radiation. In addition, aerosols smaller than 2.5 {micro}m have recently been implicated in the health effects of air pollution. Aerosol-active radioisotopes are ideal tracers for the study of atmospheric transport processes. The source terms of these radioisotopes are relatively well known, and they are removed from the atmosphere only by radioactive decay or by wet or dry deposition of the host aerosol. The progeny of the primordial radionuclide {sup 238}U are of particular importance to atmospheric studies. Uranium-238 is common throughout Earth's crust and decays to the inert gas {sup 222}Rn, which escapes into the atmosphere. Radon-222 decays by the series of alpha and beta emissions shown in Figure 1 to the long-lived {sup 210}Pb. Once formed, {sup 210}Pb becomes attached to aerosol particles with average attachment times of 40 s to 3 min.

  18. Iunconsistencies in Accumulation Rates of Black Sea Sediments Inferred from Records of Laminae and 210Pb

    NASA Astrophysics Data System (ADS)

    Crusius, J.; Anderson, R. F.

    1992-04-01

    Recently-published estimates for the age of the unit 1-unit 2 contact in Black Sea sediments based on accelerator mass spectrometry (AMS) 14C measurements [Jones, 1990; Calvert et al., 1991] appear to be older than those based on the previously published chronology based on lamina couplets [Degens et al., 1980; Hay, 1988] by a factor of 2 to 3. To help reconcile the differences, we compare sediment accumulation rates based on the 210Pb method with estimates based on lamina counts for two cores from the Black Sea abyssal plain. Accumulation rates estimated using the 210Pb technique have varied little over the last 150 years from the averages of 55 and 50 g m-2 yr-1 at stations in the western and eastern basins, respectively. These values are about a factor of 2 lower than accumulation rates derived by counting lamina couplets over the dated intervals. Close examination of the laminae suggests that the discrepancy exists both because it is difficult to count the very fine laminae and because a complete couplet is not deposited every year. In order to provide a useful stratigraphic horizon for future investigators studying sedimentary records of the Black Sea, we estimate the age of a distinct black marker horizon which can be easily identified across the entire abyssal plain to be 150±8 years (deposited in 1838±8 A.D.).

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

    PubMed

    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

  20. (210)Pb content in natural gas pipeline residues ("black-powder") and its correlation with the chemical composition.

    PubMed

    Godoy, José Marcus; Carvalho, Franciane; Cordilha, Aloisio; Matta, Luiz Ernesto; Godoy, Maria Luiza

    2005-01-01

    The present work was carried out to assess the (210)Pb content in "black-powder" found in pigging operations on gas pipelines in Brazil, in particular, on the Campos Basin gas pipeline. Additionally, the chemical composition of such deposits was determined and an eventual correlation with (210)Pb concentration evaluated. Typical "black-powder" generated in the natural gas pipeline from Campos Basin oilfield contains mainly iron oxide ( approximately 81%) and residual organic matter ( approximately 9%). The (210)Pb content ranges from 4.9 to 0.04k Bqkg(-1) and seems to be inversely correlated with the distance to the platforms. On the other hand, (226)Ra concentration is higher on the pipeline branch between the platform and the onshore installations. (228)Ra was only observed in few samples, in particular, in the samples with the highest (226)Ra content. PMID:15885858

  1. Distribution of (226)Ra-(210)Pb-(210)Po in marine biota and surface sediments of the Red Sea, Sudan.

    PubMed

    Sirelkhatim, D A; Sam, A K; Hassona, R K

    2008-12-01

    Activity concentration levels and ratios of (226)Ra, (210)Pb and (210)Po are presented 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 PortSudan harbour, Sudan. The analyses were performed adopting alpha-spectrometry, liquid scintillation and Cerenkov counting techniques. Surface sediments from this coastal region are poor in their radioactivity content in contrast to similar data reported from different coastal areas around the globe. There is surface enrichment of (210)Pb and (210)Po with respect to their progenitor (226)Ra as it is evident from the activity ratios of (210)Pb/(226)Ra (3.03+/-1.79) and (210)Po/(226)Ra (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 8.2Bq/kg and 21.9Bq/kg dry weight, respectively. Similarly, the highest concentration of (210)Po was met in Favites at 38.7Bq/kg followed by brown algae, Cystoseria sp., at 32.6Bq/kg. There is no variation seen among algal species for (210)Pb uptake, however, converse to radium and polonium, Favites (coral) was found to contain the minimum concentration of lead (3.88Bq/kg). In most species there is preferential accumulation of polonium over its parent radium as indicated by (210)Po:(226)Ra activity ratio with Cystoseria (brown algae) showing the highest value at 8.81. On the other hand, (210)Po:(210)Pb activity concentration ratio revealed that coral species Favites (9.97) and the brown algae Sargassum (1.85) have a greater tendency to accumulate (210)Po over (210)Pb, while in the rest of species; this ratio is less than unity. PMID:18774629

  2. 210Pb balance and implications for particle transport on the continental shelf, U.S. Middle Atlantic Bight

    USGS Publications Warehouse

    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.

  3. Geochronology of recent sediments from the Cariaco Trench (Venezuela) by Alpha Spectrometry of {sup 210}Pb ({sup 210}Po)

    SciTech Connect

    Arriojas, A.; Barros, H.; Palacios, D.; Sajo-Bohus, L.; Hurtado, S.; Villa, M.; Perez, K.; Alfonso, J.

    2010-08-04

    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 {alpha}- dating carried out in the country, performed with an alpha spectrometer recently funded by the IAEA.

  4. Beryllium-7 and (210)Pb atmospheric deposition measured in moss and dependence on cumulative precipitation.

    PubMed

    Krmar, M; Mihailović, D T; Arsenić, I; Radnović, D; Pap, I

    2016-01-15

    This paper focuses on analysis of the time series of (7)Be and (210)Pb activity measured in moss, and the amount, as well as duration of precipitation, to gain a better understanding of the possible relationships between airborne radionuclide deposition and precipitation. Here we consider whether the amount of these airborne radionuclides in moss samples is a cumulative measure of radionuclide deposition and decay, and a new approach for analyses of the relationships between precipitation and moss activity concentrations is suggested. Through these analyses it was shown that comparison of cumulative activity measured at one location using moss, normalized by values of cumulative amount or duration of precipitation, showed different regimes of airborne radionuclide deposition. PMID:26461139

  5. 210Pb mass accumulation rates in the depositional area of the Magra River (Mediterranean Sea, Italy)

    NASA Astrophysics Data System (ADS)

    Delbono, I.; Barsanti, M.; Schirone, A.; Conte, F.; Delfanti, R.

    2016-08-01

    Nine sediment cores were collected between 2009 and 2012 in the inner continental shelf (Mediterranean Sea, Italy) mainly influenced by the Magra River, at water depths ranging from 11 to 64 m. Mass Accumulation Rates (MARs) were calculated through 210Pb analysed by Gamma spectrometry. Three different dating models (single and two-layer CF-CS, CRS) were applied to clay normalised 210Pbxs profiles and 137Cs was used to validate the 210Pb geochronology. The maximum MAR values (>2 g cm-2 yr-1) were found in the region adjacent to the Magra River mouth and outside the Gulf of La Spezia (0.9±0.1 g cm-2 yr-1 at St. 3-C6 and 4-C4). Results from 137Cs/210Pbxs ratios calculated in Surface Mixed Layers (SMLs) evidenced the coastal boundaries of the Magra River depositional area, which is very limited towards south. Differently, in the north-west sector, fine sediments are generally driven by the Ligurian Current and move towards north-west: at the deepest and most distant station from the River mouth, the MAR value is the lowest one in the study area. Few major Magra River floods occurred during the sediment core sampling period. By using the short-lived radioisotope 7Be as a tracer of river floods, a clear 7Be signature of 2009 flood is present at St. 1-SA1C. Finally, by analyzing the clay normalised 210Pbxs profiles, a decrease of its activity dating the years 1999 and 2000 is observed in four cores, corresponding to two major Magra River floods occurring in those years.

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

    PubMed

    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

  7. 210Po and 210Pb Activity Concentrations in Cigarettes Produced in Vietnam and Their Estimated Dose Contribution Due to Smoking

    NASA Astrophysics Data System (ADS)

    Tran, Thuy-Ngan N.; Le, Cong-Hao; Chau, Van-Tao

    Smoking cigarettes contributes significantly to the increase of radiation in human body because 210Po and 210Pb exist relatively high in tobacco leaves. Therefore, these two radioisotopes in eighteen of the most frequently sold cigarette brands produced in Vietnam were examined in this study. 210Po was determined by alpha spectroscopy using a passivated implanted planar silicon (PIPS) detector after a procedure including radiochemical separation and spontaneous deposition of polonium on a copper disc (the deposition efficiency of 210Po on a copper disc was approximately 94%). Sequentially, 210Pb was determined through the ingrowth of 210Po after storing the sample solutions for approximately six months. The activity concentrations of 210Po in cigarettes ranged from 13.8 to 82.6 mBq/cigarette (the mean value was 26.4 mBq/cigarette) and the activity concentrations of 210Pb in cigarettes ranged from 13.9 to 78.8 mBq/cigarette (the mean value was 25.8 mBq/cigarette). The annual committed effective dose for smokers who smoke one pack per day was also estimated to be 295.4 µSv/year (223.0 µSv/year and 72.4 µSv/year from 210Po and 210Pb, respectively). These indicated that smoking increased the risk of developing lung cancer was approximately 60 times greater for smokers than for non-smokers.

  8. Measurement of {sup 210}Pb and its Application to Evaluate Contamination in an Area Affected by NORM Releases

    SciTech Connect

    Mosqueda, F.; Vaca, F.; Villa, M.; Hurtado, S.; Absi, A.; Manjon, G.; Garcia-Tenorio, R.

    2008-08-07

    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 {sup 210}Pb low level counting in environmental samples. {sup 210}Pb 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 {sup 210}Pb from the treated raw material, for that reason analysed riverbed sediments have enhanced {sup 210}Pb activity concentrations and hence, enhanced activity concentration of its daughter {sup 210}Po, both in secular equilibrium after two years.

  9. {sup 210}Pb atmospheric flux and growth rates of a microbial mat from the northwestern Mediterranean Sea (Ebro River Delta)

    SciTech Connect

    Sanchez-Cabeza, J.A.; Masque, P.; Martinez-Alonso, M.; Mir, J.; Esteve, I.

    1999-11-01

    Environmental archives are needed to study the variability of natural systems and the impact of man on them. Microbial mats, modern homologues of stromatolites, can be found in extreme environments such as the Ebro River Delta and were studied as potential environmental archives of atmospheric deposition. {sup 210}Pb, a radiotracer widely used in geochronology studies, was used both to determine the growth rates of a microbial mat from this environment and to estimate the {sup 210}Pb atmospheric flux in the northwestern Mediterranean Sea. The {sup 210}Pb profile showed the presence of three distinct peaks related to low growth-rate periods. This variability indicted the sensitivity of the system to external forcing. The annual atmospheric flux of {sup 210}Pb was 81.2 {+-} 1.4 B1 m{sup {minus}2}yr{sup {minus}1}, which is similar to other values found in the literature. The age profile showed two layers of differing growth rates, being 0.99 {+-} 0.10 mm yr{sup {minus}1} from the surface down to 10 mm depth. The accumulated mass profile showed a change at about 9 mm depth, corresponding to year 1983 {+-} 1. It is noteworthy that this is coincident with a strong El Nino Southern Oscillation event during 1982--1983, which has been shown to affect other ecosystems, including some in the Mediterranean area.

  10. Concentrations of /sup 207/Bi and /sup 210/Pb-/sup 210/Bi-/sup 210/Po disequilibrium in fish

    SciTech Connect

    Noshkin, V.E.; Wong, K.M.; Eagle, R.J.; Jokela, T.A.

    1984-10-01

    Radioactive /sup 207/Bi, 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 /sup 207/Bi could also be efficient accumulators of other bismuth isotopes - namely /sup 210/Bi, the daughter of naturally occurring /sup 210/Pb. Therefore, /sup 210/Bi and consequently /sup 210/Po, the decay product of /sup 210/Bi, would be expected in notable excess over the precursor /sup 210/Pb in specific tissues. To test this assumption, we compared concentrations of /sup 210/Pb, /sup 210/Bi, and /sup 210/Po in muscle, liver, and bone separated from some reef species from the Marshall Islands. Concentrations of /sup 210/Bi in muscle and liver were found to exceed those of its precursor by factors of 2 to 15. The excess /sup 210/Bi in some species, however, is not from the environmental sources (either food or water) from which /sup 207/Bi is derived. The data suggest that the excess /sup 210/Bi may be translocated to muscle and liver tissue following the decay of /sup 210/Pb in bone.

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

    PubMed

    Suriyanarayanan, S; Brahmanandhan, G M; Malathi, J; Ravi Kumar, S; Masilamani, V; Shahul Hameed, P; Selvasekarapandian, S

    2008-04-01

    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 approximately 10(3) to 10(6) while for 210Pb it ranged from approximately 10(3) to 10(5). PMID:18035457

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

    NASA Astrophysics Data System (ADS)

    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

  13. Sorption characteristics of 210Pb, 210Po and 7Be onto microparticle surfaces and the effects of macromolecular organic matter

    NASA Astrophysics Data System (ADS)

    Yang, W.; Guo, L.; Chuang, C.; Santschi, P. H.

    2011-12-01

    210Pb, 210Po and 7Be have been widely used as tracers of particle dynamics, carbon cycling, ocean circulation, sedimentation, and other geochemical and oceanographic studies. However, the pathways and mechanisms in the interactions between these radionuclides and particulate surfaces in marine environments are not well understood. Controlled laboratory experiments have been carried out to examine the interactions of 210Pb, 210Po and 7Be in ultrafiltered seawater (<1 kDa) with different microparticles, including kaolinite, SiO2, CaCO3, Al2O3, Fe2O3, MnO2 and chitin, in the presence or absence of macromolecular organic matter, such as humic acids (HA), acid polysaccharides (APS, carrageenan type V) and proteins (bovine serum albumin, BSA). Values of the log of the partition coefficient (Kd) of 210Pb between dissolved and particulate phases varied from 3.22 to 6.29, with the highest value for MnO2 and the lowest for CaCO3. LogKd values of 210Pb increased in the presence of natural organic matter compounds (e.g. HA, APS and BSA) for SiO2, CaCO3 and kaolinite, but decreased for Al2O3. 210Pb sorption on Fe2O3 and MnO2 seemed to be enhanced by humic acid but depressed by BSA. Measured logKd values for 210Po varied from 3.02 to 5.19 with the highest value for MnO2 and the lowest for kaolinite. Humic acids, APS and BSA promoted the adsorption of 210Po onto CaCO3, kaolinite, SiO2 and MnO2, but slightly decreased sorption onto Al2O3 and Fe2O3. 7Be had logKd values similar to those observed in the field, ranging from 3.5 to 4.6 with the highest value for SiO2 and the lowest for CaCO3. The highly selective adsorption on different particle surfaces resulted in fractionations between 210Pb, 210Po and 7Be, with the largest fractionation between 210Pb and 210Po (FPb/Po>10) on MnO2 in the absence of organic matter. All particles preferentially absorbed 210Pb in the presence of APS and HA (except for HA-CaCO3), whereas Al2O3, SiO2 and CaCO3 preferred 210Po to 210Pb in the presence of

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

    PubMed

    Langdon, Kate A; Warne, Michael Stj; Smernik, Ronald J; Shareef, Ali; Kookana, Rai S

    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-d16 and TCS-(13)C12). 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. PMID:23376516

  15. Washing of soils spiked with various pollutants by surfactant solutions

    SciTech Connect

    Yang, G.C.C.; Chang, J.H.

    1995-12-31

    In this study, the batch-type of washing with surfactant solutions was employed for the treatment of soils artificially contaminated with various volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals. 15 industrial grade surfactants were tested. Washing was conducing by adding surfactant solution to the soils and mixing for one hour, then centrifuging it and analyzing the supernatant. Deionized water was used for soil washing for comparison. Results indicated that deionized water performed as well as Surfactant No. 1 in washing VOC-contaminated soils. Therefore, it is concluded that the VOCs tested can be easily washed from soils by rain water. In washing PAH-contaminated soils, nonionic surfactants performed better than anionic surfactants in terms of removal efficiency. The amphoteric surfactant performed worst in washing PAH-contaminated soils. Generally, surfactants are useful in removing cadmium from soils, but are not useful for the removal of lead and copper. Amphoteric, anionic, and low pH cationic surfactants were the most effective of those tested. For PAH/heavy metals-contaminated soils, removal efficiencies were lower than that of soils containing a single contaminant.

  16. 234Th, 210Pb, 210Po and stable Pb in the central equatorial Pacific: Tracers for particle cycling

    USGS Publications Warehouse

    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

  17. 210Po and 210Pb as Tracers of Particle Cycling and Resuspension in a Dynamic Freshwater System: Case Study from the Clinton River, Southeast Michigan

    NASA Astrophysics Data System (ADS)

    Mudbidre, R.; Baskaran, M. M.; Schweitzer, L.

    2013-12-01

    Polonium-210 and 210Pb are constantly delivered to the surface waters through atmospheric deposition with a 210Po/210Pb activity ratio (AR) of < 0.10. Freshly produced suspended particles in surface waters are ';tagged' with this ratio which tends to grow towards the secular equilibrium value of 1.0. This disequilibrium between 210Po and 210Pb in freshwater system with a relatively short hydrological residence time can be utilized to quantify sediment resuspension rates and to investigate the extent of recycling of sedimentary particulate matter. From the measurements of 210Po and 210Pb in particulate matter collected in sediment traps and surficial bottom sediments at 5 different sites in the Clinton River in southeast Michigan over a period of 6 months (April - September, 2005) and subsequent modeling of these data, we report the following: i) The direct atmospheric deposition of 210Po and 210Pb collected in the sediment trap materials accounted for 1% and 0.1%, respectively, of the total deposited in the sediment trap; ii) The ranges and mean values of the 210Po and 210Pb in the sediment trap material and bottom sediments are comparable, with near identical 210Po/210Pb ratios, indicating that most of the trapped 210Po and 210Pb were delivered by the resuspension of bottom sediments; iii) The particle residence times varied from 0.3 to 4 days for 210Pb and 0.9 to 13.4 days for 210Po; and iv) The sediment resuspension rates calculated via single box model approach yielded resuspension rates ranging from 0.2 to 14.2 g cm-2 yr-1 using 210Pb and 0.1 to 1.0 g cm-2 yr-1 using 210Po. We propose that the distribution of 210Bi (and 210Bi/210Pb) would provide better insight on particle cycling in short-time scales and a brief discussion will be presented on the utility of 210Bi/210Pb ratio as a powerful tool for short-term particle cycling and as tracers of POC, PON export studies in deeper freshwater lakes.

  18. 210Pb chronology and trace metal geochemistry in the intertidal sediment of Qinjiang River estuary, China

    NASA Astrophysics Data System (ADS)

    Xia, Peng; Meng, Xianwei; Feng, Aiping; Yin, Ping; Wang, Xiangqin; Zhang, Jun

    2012-06-01

    Historical records of metal inputs were studied by using a sediment core collected from a sand-rich mudflat in the Qinjiang River estuary, China. 210Pb chronology was used to reconstruct the fluxes of Hg, Cu, Pb, Zn, Cd, Cr and As to the core site during the last 86 years. Based on the constant initial concentration model, the sedimentation rates are 1.18 cm year-1 in the top 30 cm sandy layer and 0.92 cm year-1 in the muddy bottom layer. To compensate for grain-size and mineralogy effects on metal concentrations, aluminum was used as the normalizing element. The enrichment factors ( EF) indicate that the natural inputs had prevailed up to the early 1980s. After this period, the intensity of human activities has resulted in continual increasing trend of metals towards the surface. Recent sediment samples from the Qinjiang River estuary are found moderately enriched by Cd ( EF>1.5) and slightly enriched by other metals ( EF<1.5). Considering that the drainage area of the Qinjiang River is mostly agricultural land, the increased Cd may be due to the usage of fertilizers and pesticides in agricultural activities and the combustion of fossil fuels.

  19. The 210Po and 210Pb levels in surface sediment samples in the Izmir Bay (Aegean Sea-Turkey).

    PubMed

    Saçan, Sezen; Uğur, Aysun; Sunlu, Uğur; Büyükişik, Baha; Aksu, Mehmet; Sunlu, F Sanem

    2010-02-01

    Bottom sediments reflect in general the relative contamination of a sea area. Therefore, a great deal of monitoring work has been dedicated to the analysis of bottom sediments. Izmir Bay is a very important pollution centre in Turkish Aegean coast region due to a densely populated community, industrial complex and maritime transportation, and there are many streams flowing into the bay that pass through a number of industrial and agricultural areas. It had received the majority of domestic and industrial wastewaters until the wastewater treatment plant was constructed. It is well known that sediments play an important role as reservoirs of a fraction of the pollution in aquatic systems. Therefore, sediment samples were collected monthly from three stations which are located in the inner part of the bay during the period January to December 2003. Temporal variations and seasonal changes on their (210)Po and (210)Pb contents were examined, and the activity concentrations of (210)Po and (210)Pb were found to vary from 43+/-6 to 132+/-12 and 27+/-5 to 91+/-9 Bq kg(-1) dry wt, respectively. The highest values of those natural radionuclides were measured at Karşiyaka Station because of the current systems of the bay. Seasonally, the (210)Pb levels were found to increase during the winter time for all the stations. PMID:19242813

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

    PubMed

    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

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

    PubMed

    Putyrskaya, V; Klemt, E; Röllin, S; Astner, M; Sahli, H

    2015-07-01

    In this paper the most important problems in dating lake sediments with unsupported (210)Pb are summarized and the progress in gamma-spectrometry of the unsupported (210)Pb 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 ((137)Cs, (241)Am, (239)Pu) and natural radionuclides ((40)K, (210,214)Pb, (214)Bi) 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 (210)Pb-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. PMID:25875007

  2. Particulate organic carbon export fluxes on Chukchi Shelf, western Arctic Ocean, derived from 210Po/210Pb disequilibrium

    NASA Astrophysics Data System (ADS)

    He, Jianhua; Yu, Wen; Lin, Wuhui; Men, Wu; Chen, Liqi

    2015-05-01

    Fluxes of particulate organic carbon (POC) were derived from 210Po/210Pb disequilibrium during the 4th Chinese National Arctic Research Expedition (CHINARE-4) from July 1 to September 28, 2010. Average residence times of particulate 210Po in the euphotic zone were -16.00 a to 1.54 a, which are higher than those of dissolved 210Po (-6.89 a to -0.70 a). Great excesses of dissolved 210Po were observed at all stations, with an average 210Po/210Pb ratio of 1.91±0.20, resulting from 210Pb atmospheric deposition after sea ice melt. POC fluxes from the euphotic zone were estimated by two methods (E and B) in the irreversible scavenging model. Estimated POC fluxes were 945-126 mmol C/(m2·a) and 1 848-109 mmol C/(m2·a) by methods E and B, respectively, both decreasing from low to high latitude. The results are comparable to previous works for the same region, indicating efficient biological pumping in the Chukchi Sea. The results can improve understanding of the carbon cycle in the western Arctic Ocean.

  3. Seasonal distribution patterns of 7Be and 210Pb in surface sediments in the Changjiang Estuary, China and their implication

    NASA Astrophysics Data System (ADS)

    Du, Juan; Du, Jinzhou; Huang, Dekun; Wang, Jinlong; Zhang, Jing

    2016-02-01

    The estuarine-inner shelf region of the East China Sea (ECS) is heavily impacted from the riverine input from the Changjiang River. In this study, the grain size and activities of radionuclides (7Be and 210Pb) of surface sediments collected from the Changjiang Estuary to the southern inner shelf of the ECS in June and November 2010, were measured to provide the study of the sources and the transportation pathways of surface sediments in this region. The results indicated that the grain size of surface sediments ranged from 8.1 to 251.1 μm and from 5.8 to 128.3 μm with an average of 85.1 μm and 56.6 μm in June and November 2010, respectively. Relatively large particle sizes were observed in the northwest and southeast of our study area. Meanwhile, the grain size increased offshore. The activities of 7Be in the surface sediments were high in the nearshore stations and the activities of 210Pbex in the surface sediments increased from north to south. For 7Be, more than 90% was decayed before deposition into the surface sediment. However, most 210Pb (99%) was deposited into the sediment. Both7Be and 210Pb need to be input into the inner shelf by boundary scavenging processes to balance the budget.

  4. Atmospheric fluxes of (7)Be and (210)Pb on monthly time-scales and during rainfall events at Stony Brook, New York (USA).

    PubMed

    Renfro, Alisha A; Cochran, J Kirk; Colle, Brian A

    2013-02-01

    The particle-reactive radionuclides (7)Be and (210)Pb have been employed extensively as tracers and chronometers for a variety of aquatic and terrestrial processes. Both radionuclides are delivered to the Earth's surface from the atmosphere, and in order to use them effectively as natural tracers, an understanding of variations in atmospheric fluxes of these radionuclides due to latitudinal differences and storm events is required. The monthly atmospheric fluxes of (7)Be and (210)Pb, measured from April-2008 to December-2009 at Stony Brook, NY, ranged from 67 to 385 Bq m(-2) and 6.7 to 16.7 Bq m(-2), respectively. Composite annual atmospheric fluxes over the sampling period were 3110 ± 1200 Bq m(-2) y(-1) for (7)Be and 146 ± 50 Bq m(-2) y(-1) for (210)Pb and were similar to geographically comparable sites. The monthly atmospheric fluxes of (7)Be and (210)Pb were significantly correlated with rainfall. The (7)Be/(210)Pb ratio in the monthly samples varied seasonally, with values of ∼10-11 during the winter months and ∼20-28 during the spring - fall. The pattern of seasonal variation in (7)Be fluxes and (7)Be/(210)Pb ratios is most consistent with that observed in surface air at continental sites in which more frequent deep convective storms occur during the summer and therefore result in an increased transport of (7)Be from the upper troposphere to the Earth's surface. An additional factor may be that the winds at Stony Brook were dominantly from the northwest during the winter of 2009 and so were characterized by low (7)Be/(210)Pb ratios while in the spring, winds from the southwest brought marine air with higher (7)Be/(210)Pb ratios to the sampling site. Fluxes of (7)Be and (210)Pb also were measured over two long (16-24 h) and two short (∼1 h) intense periods of rainfall in June and July 2009. Fluxes of (7)Be and (210)Pb continued throughout the short events, but the two radionuclides showed different patterns during the long events. While the entirety of

  5. Sulfide precipitates at 21/sup 0/N on the East Pacific Rise: /sup 226/Ra, /sup 210/Pb and /sup 210/Po

    SciTech Connect

    Finkel, R.C.; Macdougall, J.D.; Chung, Y.C.

    1980-09-01

    Sulfide samples collected by the deep submersible ALVIN from hydrothermal vents at 21/sup 0/N on the East Pacific Rise have extremely variable contents of uranium series nuclides. In samples we have analyzed, /sup 210/Pb and /sup 210/Po activities vary by more than an order of magnitude within the same vent. In two out of three samples measured /sup 210/Po activities are hgiher than the parent /sup 210/Pb activities. Consideration of /sup 210/Pb/Pb in particulate sulfide filtered from hot vent water indicates that the lead in these deposits has a basalt as opposed to a seawater origin. Comparison of /sup 210/Po and /sup 210/Pb contents of active and inactive vent particulates suggests that the cycle of buildup, cessation and decay by oxidation of these sulfide chimneys is measured in tens to a few hundreds of years.

  6. Influence of organic matter on the adsorption of 210Pb, 210Po and 7Be and their fractionation on nanoparticles in seawater

    NASA Astrophysics Data System (ADS)

    Yang, Weifeng; Guo, Laodong; Chuang, Chia-Ying; Santschi, Peter H.; Schumann, Dorothea; Ayranov, Marin

    2015-08-01

    Improved applications of 210Po, 210Pb and 7Be as geochemical proxies require more detailed understanding of their interactions with particles. Here, laboratory sorption experiments were carried out to examine the adsorption of 210Po, 210Pb and 7Be and their fractionation on inorganic nanoparticles, including SiO2, CaCO3, Al2O3, TiO2 and Fe2O3, in the presence or absence of macromolecular organic compounds (MOCs) that include humic acids (HA), acid polysaccharides (APS) and proteins (BSA), in natural seawater. Results showed that nanoparticle sorption was not greatly enhanced over that of microparticles as would be expected from their much higher specific surface areas, likely indicating their aggregation in seawater. It was found that synergistic interactions between inorganic nanoparticles, MOCs, and radionuclides determined the sorption, although their adsorption was particle composition-dependent. MOCs enhanced the sorption of selected nuclides on most nanoparticles. On average, in the presence of MOCs, partition coefficients (Kc) of 210Po, 210Pb, and 7Be on nanoparticles increased 2.9-, 5.0- and 5.9-fold, respectively. The effect of MOCs could be explained for 210Po and 210Pb from their different log ⁡Kc values on inorganic nanoparticles. In addition, fractionation effects between 210Po and 210Pb (or between 210Pb and 7Be) could be quantified from their relative log ⁡Kc values on end-member sorbent components. Applications of both 210Po-210Pb and 7Be-210Pb pairs as particle dynamics tracers could be more quantitative when the nature of the organic coatings is taken into account.

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

    SciTech Connect

    Smoak, J.M.; DeMaster, D.J.; Pope, R.H.; Kuehl, S.A.; McKee, B.A.

    1996-06-01

    Excess {sup 234}Th and {sup 210}Pb seabed inventories were measured in cores collected from the Amazon continental shelf to examine particle scavenging and seabed dynamics. Typical excess {sup 210}Pb inventories range from 100 to 300 dpm cm{sup {minus}2}, and the total excess {sup 210}Pb inventory for the Amazon shelf was determined to be 2.7 x 10{sup 17} dpm. The {sup 210}Pb 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 {sup 210}Pb 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 {sup 210}Pb to the Amazon continental shelf with relatively small contributions from riverine input (31%), atmospheric fallout (2.3%), and in-situ production (0.1%). The {sup 234}Th 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 {sup 234}Th excess seabed inventories show large spatial and seasonal variability, with a range from 0 to 22 dpm cm{sup {minus}2}. This approach indicates that for most of the shelf, the inventories of the shorter-term tracer ({sup 234}Th) are less than predicted by the inventories of the longer-term tracer ({sup 210}Pb). There are two explanations for this trend. The first is that a larger portion of the {sup 234}Th inventory occurs in the fluid muds or the water column relative to {sup 210}Pb. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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

  10. 137Cs and excess 210Pb deposition patterns in estuarine and marine sediment in the central region of the Great Barrier Reef Lagoon, north-eastern Australia.

    PubMed

    Pfitzner, John; Brunskill, Gregg; Zagorskis, Irena

    2004-01-01

    This paper focuses on the distribution of 137Cs and 210Pb(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 210Pb(xs) and 137Cs atmospheric deposition and present day terrestrial inventories in north-eastern Australia are presented. 210Pb(xs) and 137Cs 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 137Cs and 210Pb(xs), are explored. In relation to inventories of 210Pb(xs), 60% of atmospheric fallout 137Cs 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 137Cs distribution in these cores can be a useful independent tracer which provides confirmation of MARs calculated from the decay of 210Pb(xs). PMID:15245842

  11. Bayesian integration of radioisotope dating (210Pb, 137Cs, 241Am, 14C) and an 18-20th century mining history of Brotherswater, English Lake District

    NASA Astrophysics Data System (ADS)

    Schillereff, Daniel; Chiverrell, Richard; Macdonald, Neil; Hooke, Janet; Welsh, Katharine; Piliposyan, Gayane; Appleby, Peter

    2014-05-01

    Lake sediment records are often a useful tool for investigating landscape evolution as geomorphic changes in the catchment are reflected by altered sediment properties in the material transported through the watershed and deposited at the lake bed. Recent research at Brotherswater, an upland waterbody in the Lake District, northwest England, has focused on reconstructing historical floods from their sedimentary signatures and calculating long-term sediment and carbon budgets from fourteen sediment cores extracted from across the basin. Developing accurate chronological control is essential for these tasks. One sediment core (BW11-2; 3.5 m length) from the central basin has been dated using artificial radionuclide measurements (210Pb, 137Cs, 241Am) for the uppermost sediments and radiocarbon (14C) for lower sediments. The core appears to span the past 1500 years, however a number of problems have arisen. We present our explanations for these errors, the independent chronological techniques used to generate an accurate age-depth model for this core and methods for its transferral to the other 13 cores extracted from the basin. Two distinct 137Cs markers, corresponding to the 1986 Chernobyl disaster and 1960s weapons testing, confirm the 210Pb profile for sediment deposition since ~1950, but calculations prior to this appear erroneous, possibly due to a hiatus in the sediment record. We used high-resolution geochemical profiles (measured by XRF) to cross-correlate with a second 210Pb-dated chronology from a more distal location, which returned more sensible results. Unfortunately, the longer 14C sequence exhibits two age-reversals (radiocarbon dates that are too old). We believe the uppermost two dates are erroneous, due to a shift in inflow location as a flood prevention method ~1900 A.D., dated using information from historical maps. The lower age-reversal coincides with greater supply of terrigenous material to the lake (increased Zr, K, Ti concentrations

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

    USGS Publications Warehouse

    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.

  13. A revision factor to the Cutshall self-attenuation correction in (210)Pb gamma-spectrometry measurements.

    PubMed

    Jodłowski, Paweł

    2016-03-01

    The Cutshall transmission method of determination of self-attenuation correction in (210)Pb measurements by gamma-spectrometry gives the results burdened with errors of up to 10%. The author proposes introducing into the Cutshall correction Cs,Cuts an additional revision factor CCs,Cuts to eliminate errors. The proposed formula of the revision factor describes the CCs,Cuts value depending on the experimentally obtained Cs,Cuts correction. Formula holds true in wide ranges of the measurement geometries and linear attenuation coefficients of both the standard and the sample. PMID:26702546

  14. Measurements of210Pb,137Cs, organic carbon and trace elements in sediments of the Illinois and Mississippi rivers

    USGS Publications Warehouse

    Cahill, R.A.; Autrey, A.D.

    1987-01-01

    Radiometric dating of sediment accumulations by137Cs and210Pb has been successfully initiated in the Illinois and Mississippi Rivers. Sedimentation rates measured at 13 locations range from 0.7 to 3.6 cm/y. Chemical analysis has been completed for up to 45 major and trace elements in core samples. The upper Illinois River contains higher metal levels than the Mississippi River. The amount of carbon (energy) lost to sediments in large floodplain rivers is estimated between 370 and 4000 g/m2/y. ?? 1987 Akade??miai Kiado??.

  15. Dating of coastal marine sediments: 210Pb versus 137Cs signal on the Danube-influenced Black Sea shelf

    NASA Astrophysics Data System (ADS)

    Friedrich, Jana; Laptev, Gennady

    2010-05-01

    Coastal marine sediments represent a natural archive of pelagic processes, coastal erosion and river discharge of suspended matter. Correct dating of those sediments is a prerequisite for chronological reconstruction of the flux of pollutants and organic matter from the water column to the sediments and hence, the reconstruction of the pollution and eutrophication events. In the reconstruction of the sedimentation history during the pre-industrial and industrial periods, which usually spans the past 100 years, the natural occurring radionuclide 210Pb and the artificial radionuclides 137Cs and 241Am are widely applied tracers. 137Cs is used as an independent time marker for end the atmospheric bomb test fallout in 1963 and the Chernobyl accident in 1986. As the 137Cs signal is often weakened due to its mobility in sediments, 241Am, less mobile than 137Cs and derived from decay the bomb fallout of 241Pu, is used as a second time marker of the 1963 event. The northwestern shelf of the Black Sea has been seriously affected by eutrophication and pollution from the late 1960's to the mid-1990's, largely triggered by Danube River input of nutrients and pollutants. The aim of our study is ultimately to reconstruct the eutrophication history and recycling of nutrients following the deposition of organic matter. The ‘memory effect' of sediment recycling plays a critical role in maintaining eutrophic conditions in enclosed seas such as the Black Sea. Here we present results from sediment cores taken within the Danube River plume on the shallow northwestern shelf of the Black Sea. The cores have been dated in two laboratories to rule out artifacts. The sediment record is repeatedly interrupted by so-called turbidites that consist of stiff clay. The clay horizons display a drop in unsupported 210Pb and 137Cs and a higher signal of supported 210Pb than the non-clay horizons. Below the turbidite, the unsupported 210Pb and 137Cs increase again to values above the turbidite. This

  16. Alkaline biosolids and EDTA for phytoremediation of an acidic loamy soil spiked with cadmium.

    PubMed

    Wong, Jonathan W C; Wong, Winnie W Y; Wei, Zhenggui; Jagadeesan, Hema

    2004-05-25

    A greenhouse experiment was conducted to investigate the growth of Brassica juncea and Cd phytoextraction in a mimicked Cd contaminated acidic loamy soil amended with alkaline biosolids, prepared from sewage sludge and coal fly ash, in the presence and absence of EDTA at 2 mmol kg(-1). The acidic loamy soil was spiked with 0, 5, 20, 50 and 100 mg Cd kg(-1) in the form of CdCO(3) and then amended with 4% alkaline biosolids (w/w). Alkaline biosolids and 0.12% CaCO(3) amendments resulted in a higher biomass than unamended soil spiked with 20 mg kg(-1) Cd where plants did not survive and of the two amendments, alkaline biosolids amendment had higher plant dry weight yield and phytoextraction of Cd. Adding 2 mmol kg(-1) EDTA to alkaline biosolids amended soil significantly increased the solubility of Cd ions by 9- to 29-fold, but plant Cd accumulation decreased by a factor of 24-48%. The results indicate that alkaline biosolids amendment is an effective approach for assisting growth of B. juncea and phytoextraction of Cd from the contaminated acidic loamy soil, but further application of chelating agents did not enhance the phytoextraction efficiency of Cd. PMID:15081709

  17. Adsorption characteristics of 210Pb, 210Po and 7Be onto micro-particle surfaces and the effects of macromolecular organic compounds

    NASA Astrophysics Data System (ADS)

    Yang, Weifeng; Guo, Laodong; Chuang, Chia-Ying; Schumann, Dorothea; Ayranov, Marin; Santschi, Peter H.

    2013-04-01

    210Po, 210Pb and Be isotopes (e.g. 7Be and 10Be) have long been used as proxies of particle/sediment dynamics, carbon cycling, and oceanographic investigations of coupled processes. However, adsorption characteristics and interactions between these nuclides and particle surfaces remain poorly understood. Laboratory studies have been conducted to examine the adsorption of 210Po, 210Pb and 7Be onto micro-particles, including marine suspended particulate matter, kaolinite, Al2O3, SiO2, CaCO3, Fe2O3, MnO2, and chitin in natural seawater (<1 kDa), and the role of macromolecular organic compounds (MOCs), including humic acids (HA), acid polysaccharides (APS) and proteins (BSA) in regulating the adsorption process. In the absence of MOCs, the partition coefficients (Kd, reported in log Kd) range from 3.02 to 5.19 for 210Po, from 3.22 to 6.29 for 210Pb, and from 3.57 to 4.65 for 7Be. Ferric and manganese oxides are the strongest sorbents of 210Po and 210Pb, comparing with SiO2 and CaCO3. In the presence of the protein BSA, both SiO2 and CaCO3 preferentially adsorb 210Po over 210Pb, whereas the opposite effect was observed in the presence of acid polysaccharides, indicating that proteins could enhance the adsorption of 210Po and acid polysaccharides enhance the adsorption of 210Pb. The log Kd values of both 210Po and 210Pb in the presence of MOCs become similar (log Kd at ˜4.0) for all lithogenic and biogenic particles, suggesting that their adsorption is likely controlled by specific natural organic compounds associated with particle surfaces. For 7Be, the highest and lowest log Kd value was measured, in general, on SiO2 and CaCO3, respectively, consistent with field observations. Nevertheless, the log Kd values of 7Be varied little between particle types regardless of the presence or absence of MOCs, suggesting that the adsorption of Be on particle surfaces is less affected by particle composition or MOCs. These results indicate that 7Be and 10Be could quantitatively

  18. 210Pb-226Ra chronology reveals rapid growth rate of Madrepora oculata and Lophelia pertusa on world's largest cold-water coral reef

    NASA Astrophysics Data System (ADS)

    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

  19. 210Po and 210Pb trophic transfer within the phytoplankton-zooplankton-anchovy/sardine food web: a case study from the Gulf of Lion (NW Mediterranean Sea).

    PubMed

    Strady, Emilie; Harmelin-Vivien, Mireille; Chiffoleau, Jean François; Veron, Alain; Tronczynski, Jacek; Radakovitch, Olivier

    2015-05-01

    The transfer of (210)Po and (210)Pb 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 (210)Po and (210)Pb 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 (210)Po, (210)Pb activity concentrations and (210)Po/(210)Pb 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 (210)Po bioaccumulation in the GoL remains at a constant level from the first (dominated by phytoplankton) to the second trophic level (zooplankton), while (210)Pb bioaccumulation shows an increase in winter. Based on stable N isotope ratios and (210)Po activity concentrations measured in anchovies and sardines, we evidence (210)Po bio-magnification along the trophic food web of these two planktivorous pelagic fishes. PMID:25771222

  20. Seasonal and spatial variations of 210Po and 210Pb activity concentrations in Mytilus galloprovincialis from Croatian coast of the Adriatic Sea.

    PubMed

    Rožmarić, Martina; Rogić, Matea; Benedik, Ljudmila; Štrok, Marko; Barišić, Delko

    2013-11-01

    Results of 2 years monitoring of (210)Po and (210)Pb activity concentrations in soft tissue of the species Mytilus galloprovincialis from Croatian part of the Adriatic coast are presented. The samples were collected at thirteen coastal stations (some of which are also a part of the Mediterranean Mussel Watch Project) in spring and autumn of 2010 and 2011. The collected mussels were ranging between 4 cm and 6 cm in shell length. After sample pre-treatment lead and polonium were radiochemically separated on Sr resin. (210)Po was determined by alpha-particle spectrometry and (210)Pb was determined, via (210)Bi, by a low-level gas proportional counter. The results of (210)Po activity concentrations were found to vary between (104±11) and (1421±81) Bq kg(-1) dry weight while (210)Pb activity concentrations were much lower and in range (8.2±5.3)-(94.1±29.8) Bq kg(-1) dry weight. Higher (210)Po and (210)Pb activity concentrations were determined in spring period. The inter-site differences seen in their activity concentrations can be due to natural background levels of sites. The (210)Po/(210)Pb activity concentration ratios in all cases exceeded unity for all mussel samples and ranged between 4.0 and 47.9. PMID:23932819

  1. [Vertical distribution and relationship between 210Pb(ex) activities and nutrients in sediment cores of two different eutrophication level lakes].

    PubMed

    Wang, Xiao-Lei; Yang, Hao; Gu, Zhu-Jun; Zhang, Ming-Li

    2014-07-01

    The 210Pb(ex) activities and nutrient (TOC, TN and TP) contents in sediment cores of Fuxian Lake and Dianchi Lake were measured by traditional methods, as well as their vertical distribution and relationship were also comparatively analyzed in this paper. The study results indicated that the vertical distributions of 210Pb(ex) and nutrients were significantly different between Fuxian Lake and Dianchi Lake. The variation amplitude of 210Pb(ex) activities in Dianchi Lake was higher than that in Fuxian Lake. The disordered distribution characteristics of 210Pb(ex) in Dianchi Lake surface sediments were closely related to physicochemical migration of lead caused by human activities. The variation trends of nutrients in sediment cores were corresponded to local natural evolution and human activities in different historical periods. Relationship between 210Pb(ex) activities and nutrients were mainly affected by the nutrition level of lakes. The greater the lake eutrophication level was, the stronger the correlation was found. To the individual nutrient indicators, similar characteristics were shown in the two lakes, and the order was TOC > TP > TN. PMID:25244838

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Assessment of measurement result uncertainty in determination of (210)Pb with the focus on matrix composition effect in gamma-ray spectrometry.

    PubMed

    Iurian, A R; Pitois, A; Kis-Benedek, G; Migliori, A; Padilla-Alvarez, R; Ceccatelli, A

    2016-03-01

    Reference materials were used to assess measurement result uncertainty in determination of (210)Pb by gamma-ray spectrometry, liquid scintillation counting, or indirectly by alpha-particle spectrometry, using its daughter (210)Po in radioactive equilibrium. Combined standard uncertainties of (210)Pb massic activities obtained by liquid scintillation counting are in the range 2-12%, depending on matrices and massic activity values. They are in the range 1-3% for the measurement of its daughter (210)Po using alpha-particle spectrometry. Three approaches (direct computation of counting efficiency and efficiency transfer approaches based on the computation and, respectively, experimental determination of the efficiency transfer factors) were applied for the evaluation of (210)Pb using gamma-ray spectrometry. Combined standard uncertainties of gamma-ray spectrometry results were found in the range 2-17%. The effect of matrix composition on self-attenuation was investigated and a detailed assessment of uncertainty components was performed. PMID:26653212

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

    PubMed

    Aoun, M; El Samad, O; Bou Khozam, R; Lobinski, R

    2015-02-01

    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 (210)Po and (210)Pb 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 (210)Pb was 98.7 Bq/kg fresh weight while (210)Po 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 (210)Po and (210)Pb 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. PMID:25461512

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Assessment of the biological and chemical availability of the freshly spiked and aged DDE in soil.

    PubMed

    Škulcová, L; Neuwirthová, N; Hofman, J; Bielská, L

    2016-05-01

    The study compared the ability of various chemical methods (XAD, β-hydroxypropylcyclodextrin - HPCD) and solid phase micro-extraction (SPME)) to mimic earthworm uptake from two similar soils containing either spiked or aged p,p´-DDE, thus representing two extreme scenarios with regard to the length of pollutant-soil contact time and the way of contamination. The extent of bioaccumulation was assessed at fixed exposure periods (10 and 21 days) and at equilibrium derived from uptake curves by multiple-point comparison or kinetic modeling. The decision on the best chemical predictor of biological uptake differed. The degree of bioaccumulation at equilibrium was best predicted by XAD while HPCD rather reflected the extent of accumulation derived after 21 days when, however, steady-state was not reached for spiked p,p´-DDE. SPME seemed to underestimate the uptake of aged p,p´-DDE, probably of the fraction taken up via soil particles. Thus, the degree of predictability seems to be associated with the capability of the chemical method to mimic the complex earthworm uptake via skin and intestinal tract as well as with the quality of biological data where the insufficient length of exposure period appears to be the major concern. PMID:26840523

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

    SciTech Connect

    Huebner, H.J.; Brown, K.W.; Donnelly, K.C.; He, L.Y.

    1994-12-31

    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.

  8. Timescales of degassing and crystallization implied by 210Po- 210Pb- 226Ra disequilibria for andesitic lavas erupted from Arenal volcano

    NASA Astrophysics Data System (ADS)

    Reagan, Mark K.; Tepley, Frank J.; Gill, James B.; Wortel, Matthew; Garrison, Jennifer

    2006-09-01

    Disequilibrium between 210Po, 210Pb, and 226Ra was measured on whole rocks and plagioclase mineral separates erupted between 1968 and 2003 from Arenal volcano with a goal of monitoring the volatile fluxing and crystallization in the decades and years leading up to eruption. Degassing during the eruption was found to remove nearly all 210Po from Arenal lavas, which appears to be true of lava eruptions in general. Most of Arenal's lavas have ( 210Pb)/( 226Ra) ratios within 20% of equilibrium, indicating that most of the magmas involved in this eruption did not have strong, persistent fluxes of 222Rn in or out of the system during the decades leading to eruption. This is consistent with a time-frame of differentiation from basalt to basaltic andesite exceeding a century. Lava erupted in 1971 had ( 210Pb) in excess of ( 226Ra) by as much as a factor of 2. These lavas were the first to mark the change in geochemical trends that were likely caused by the arrival of a new magma at the surface at Arenal [Ryder, C.H., Gill, J.B., Tepley III, F., Ramos, F., Reagan, M., this issue. Closed to open system differentiation at Arenal Volcano (1968-2003). Journal of Volcanology and Geothermal Research.], suggesting that the 210Pb excess was related to the first appearance of this magma. The high ( 210Pb)/( 226Ra) ratio in this lava apparently reflects Rn-degassing from large volumes of underlying magma and/or extraction of Rn from conduit-area rocks or fluids due to deformation and heating. Plagioclase mineral separates had 210Po- 210Pb- 226Ra disequilibrium patterns suggesting a growth period stretching over a period of more than 50 years up to the time of eruption.

  9. 210Po and 210Pb distribution, dissolved-particulate exchange rates, and particulate export along the North Atlantic US GEOTRACES GA03 section

    NASA Astrophysics Data System (ADS)

    Rigaud, S.; Stewart, G.; Baskaran, M.; Marsan, D.; Church, T.

    2015-06-01

    Vertical profiles of 210Po and 210Pb in the water column were measured in the dissolved phase (<0.45 μm), and small (0.8-51 μm) and large (>51 μm) particles at seven stations along the US GEOTRACES North Atlantic Zonal Transect (GA03). Mass balance calculations were employed to assess nuclide exchange rates at the dissolved-small particle interface and between small and large particles, and to quantify export with settling large particles. 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 particle in 210Po bioaccumulation and export. In stations near the coast, this link is more complex due to the variable source of biogenic material and temporal changes in the surface biogeochemical and physical conditions. At depth, 210Po exhibits significant widespread deficit with respect to 210Pb that could in part be attributed to in situ 210Po scavenging and may be related to surface biological productivity. As previously reported the 210Pb scavenging rates in the surface ocean were higher at ocean margins. At depth, 210Pb scavenging increases with depth and eastward due to the increase of adsorption sites available in the benthic layers and to a regional contribution of benthic 210Pb scavenging and/or particle flux, respectively. The benthic nepheloid layer (BNL) and the Hydrothermal TAG plume distinctly enhance 210Pb scavenging due to increased surface adsorption in association with resuspended or freshly formed particles. In contrast, 210Po is not seen to be significantly scavenged in these environments due to its relatively short half-life and the long residence time of particles.

  10. Partitioning and Fractionation of 210Pb, 210Po and 7Be During Their Interactions With Inorganic and Organic Nanoparticles in Seawater

    NASA Astrophysics Data System (ADS)

    Guo, L.; Yang, W.; Chuang, C.; Santschi, P. H.; Schumann, D.; Ayranov, M.

    2012-12-01

    Controlled laboratory experiments were carried out to examine the role of natural organic matter in regulating the partitioning and fractionation of particle-reactive radionuclides 210Pb(II), 210Po(-II, II, IV) and 7Be(II) during their interactions with colloidal or nanoparticles in seawater. Selected nanoparticles with similar sizes (20 nm), including SiO2, CaCO3, Al2O3, TiO2, and Fe2O3, and macromolecular organic matter including humic acids (HA), acid polysaccharides (APS, carrageenan type V), proteins (bovine serum albumin, BSA), and extracellular polymeric substances (EPS) were used to examine the partition coefficients (Kd) of 210Pb, 210Po and 7Be between dissolved and colloidal phases in the <1 kDa seawater. Similar Kd values were observed for 210Pb, 210Po and 7Be during their interactions with either HA or BSA, showing no significant fractionation between these isotopes. However, there was a significant fractionation between nuclides in the APS or EPS treatment, with 1-2 orders of magnitude difference in Kd values following the order of Po > Pb > Be. For inorganic nanoparticles, SiO2 and CaCO3 had lower affinity for both 210Po and 210Pb, while TiO2 or Fe2O3 had the highest affinity for 210Pb with an overall high Kd value. Fe2O3 also had the highest affinity for 7Be with a Kd value 400 times higher than that of CaCO3. In binary systems with both inorganic and organic nanoparticles, except for Fe2O3, the Kd values for 210Pb, 210Po and 7Be all increased by varying degrees compared to pure inorganic sorbents, implying that the interactions between organic and inorganic particles in most cases promote stronger sorption of these nuclides on nanoparticles. In contrast, experimental treatments with Fe2O3 and model organic compounds decreased the Kd values for 210Pb and 7Be, suggesting the coating of organic matter on high affinity sorbents would depress the sorption of trace elements on nanoparticle surfaces. These results highlight the importance of chemical

  11. An Improved Method to Determine {sup 210}Pb, {sup 210}Bi and {sup 210}Po in air Aerosol Filters

    SciTech Connect

    Miguel, E. G. San; Bolivar, J. P.; Teran, T.

    2008-08-07

    {sup 222}Rn daughters (e.g. {sup 210}Pb, {sup 210}Po, {sup 210}Bi) have been widely used to study a variety of atmospheric processes. Many works in literature about {sup 222}Rn daughters do not specify the way by the activities of these radionuclides are calculated. Besides, {sup 210}Po corrections due to the in-growth of {sup 210}Bi, if taken into account, are not indicated. In this work, the increase in uncertainties of radionuclides activities due to delay between air sampling and radionuclides determinations have been evaluated and the influence of neglecting the contribution of {sup 210}Bi in-growth to {sup 210}Po determination has been estimated. The results indicate that, in general, ignoring the {sup 210}Bi in-growth in {sup 210}Po determinations lead to significant differences (could reach until 100%) between the estimation of {sup 210}Po activity and its true value.

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

    PubMed

    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

  13. 210Pb and 210Po, manganese and iron cycling across the O2/H2S interface of a permanently anoxic fjord: Framvaren, Norway

    USGS Publications Warehouse

    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.

  14. Time-efficient method for the determination of 210Pb, 210Bi, and 210Po activities in seawater using liquid scintillation spectrometry.

    PubMed

    Biggin, Colin D; Cook, Gordon T; MacKenzie, Angus B; Pates, Jacqueline M

    2002-02-01

    A novel method has been developed for determining the natural decay series radionuclides (NDS), 210Pb, 210Bi, and 210Po, in seawater by way of state-of-the-art liquid scintillation spectrometry. For 210Pb analysis, the method makes use of a 212Pb yield tracer, prepared by ion exchange separation from aged Th(NO3)4. 210Bi recovery is determined using 207Bi as the yield tracer, and 210Po is determined using the conventional 208Po yield tracer. The limits of detection for this method are 0.32, 0.34, and 0.004 mBq 1-1 for 210Pb, 210Bi, and 210Po, respectively. The analysis can be completed within 10 days, as compared with up to one year for traditional methods. Results are presented for a preliminary study of 210Pb, 210Bi, and 210Po in the dissolved and particle-bound phases of Irish Sea water. PMID:11838694

  15. (210)Po and (210)Pb activity concentrations in Mytilus galloprovincialis from Croatian Adriatic coast with the related dose assessment to the coastal population.

    PubMed

    Rožmarić, Martina; Rogić, Matea; Benedik, Ljudmila; Štrok, Marko; Barišić, Delko; Gojmerac Ivšić, Astrid

    2012-06-01

    Activity concentrations of (210)Po and (210)Pb in the species Mytilus galloprovincialis from Croatian Adriatic coast were determined. The samples were collected in thirteen sampling places which are also a part of Croatian Mediterranean mussel watch project. The results of (210)Po and (210)Pb activity concentrations were found to vary between (22.1±2.5)-(207±21) Bq kg(-1) fresh weight and (2.8±1.4)-(9.3±0.7) Bq kg(-1) fresh weight, respectively. (210)Po/(210)Pb ratio ranged between 6.2 and 30.7. The highest measured activities were found in the enclosed basins of the Neretva channel, where the majority of Croatian mussel cultivation is taking place. The estimated consequent average total annual effective ingestion dose due to (210)Po and (210)Pb from mussel consumption in Croatian coastal region is 202±99 μSv with 96% contribution of (210)Po to the total effective dose. PMID:22342336

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

    PubMed

    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

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

    SciTech Connect

    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.

  18. Degradation of phenanthrene and pyrene in spiked soils by single and combined plants cultivation.

    PubMed

    Cheema, Sardar Alam; Imran Khan, Muhammad; Shen, Chaofeng; Tang, Xianjin; Farooq, Muhammad; Chen, Lei; Zhang, Congkai; Chen, Yingxu

    2010-05-15

    The present study was conducted to investigate the capability of four plant species (tall fescue, ryegrass, alfalfa, and rape seed) grown alone and in combination to the degradation of phenanthrene and pyrene (polycyclic aromatic hydrocarbons, PAHs) in spiked soil. After 65 days of plant growth, plant biomass, dehydrogenase activity, water-soluble phenolic (WSP) compounds, plant uptake and accumulation and residual concentrations of phenanthrene and pyrene were determined. Our results showed that presence of vegetation significantly enhanced the dissipation of phenanthrene and pyrene from contaminated soils. Higher degradation rates of PAHs were observed in the combined plant cultivation (98.3-99.2% phenanthrene and 88.1-95.7% pyrene) compared to the single plant cultivation (97.0-98.0% phenanthrene and 79.8-86.0% pyrene). Contribution of direct plant uptake and accumulation of phenanthrene and pyrene was very low compared to the plant enhanced dissipation. By contrast, plant-promoted biodegradation was the predominant contribution to the remediation enhancement. The correlation analysis indicates a negative relation between biological activities (dehydrogenase activity and WSP compounds) and residual concentrations of phenanthrene and pyrene in planted soils. Our results suggest that phytoremediation could be a feasible choice for PAHs contaminated soil. Moreover, the combined plant cultivation has potential to enhance the process. PMID:20079966

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

    SciTech Connect

    Fox, R.V.; Mincher, B.J.; Holmes, R.G.G.

    1999-08-01

    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.

  20. Prediction of [3-(14)C]phenyldodecane biodegradation in cable insulating oil-spiked soil using selected extraction techniques.

    PubMed

    Dew, Nadia M; Paton, Graeme I; Semple, Kirk T

    2005-11-01

    This study investigated the use of an aqueous hydroxypropyl-beta-cyclodextrin (HPCD) shake extraction in predicting microbial mineralisation and total loss of [3-(14)C]phenyldodecane associated activity in soils spiked with cable insulating oil; phenyldodecane represents a major constituent of cable insulating oil. Direct comparisons were made between freshly spiked and aged soils, and following composting. Soil was spiked with [3-(14)C]phenyldodecane (10mg kg(-1)) and stored in microcosms and aged for 1, 23, 44, 65, 90 and 153 d. At each sample time point, a variety of analyses were performed to assess the relationship between chemical and biological techniques in determining mineralisation and loss of (14)C-activity in soils under composting and non-composting conditions. Methods included determination of total (14)C-activity remaining, dichloromethane (DCM) and HPCD extractions. Mineralisation assays were also carried out to quantify the fraction of (14)C-phenyldodecane associated activity available for degradation in the soil at each time point. DCM and HPCD extractability were compared to contaminant mineralisation and to total loss of (14)C-phenyldodecane associated activity from the microcosms, after 153 d incubation. Poor relationships were found between (i) the amount of (14)C-activity mineralised and the fraction removed from the soils using DCM extraction and (ii) DCM extraction and total loss of [(14)C]phenyldodecane associated activity from the soil systems. Good relationships were observed between (i) the amount of (14)C-activity mineralised and the fraction removed from the soils using the HPCD extraction and (ii) HPCD extraction and total loss of [(14)C]phenyldodecane associated activity from the soil systems. The results of this study indicate that an aqueous HPCD extraction may be a useful tool in assessing the microbial availability of phenyldodecane in freshly and aged spiked soils. PMID:15949878

  1. 210Pb-226Ra chronology reveals rapid growth rate of Madrepora oculata and Lophelia pertusa on world's largest cold-water coral reef

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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 similar accurate age

  2. VULNERABILITY OF HEADWATER CATCHMENT RESOURCES TO INCIDENCES OF 210PB EXCESS AND 137CS RADIONUCLIDE FALLOUT

    EPA Science Inventory

    Recent identification of elevated excess 210Pb (≤302.6 mBq L-1) and 137Cs (≤ 111.3 mBq L-1) activity in drinking water wells up to 20 m depth indicates some transport of airborne radionuclide fallout beyond soils in the Shaker Village c...

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

    PubMed

    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

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

    PubMed

    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

  5. Soil acidification as a confounding factor on metal phytotoxicity in soils spiked with copper-rich mine wastes.

    PubMed

    Ginocchio, Rosanna; De la Fuente, Luz María; Sánchez, Pablo; Bustamante, Elena; Silva, Yasna; Urrestarazu, Paola; Rodríguez, Patricio H

    2009-10-01

    Pollution of soil with mine wastes results in both Cu enrichment and soil acidification. This confounding effect may be very important in terms of phytotoxicity, because pH is a key parameter influencing Cu solubility in soil solution. Laboratory toxicity tests were used to assess the effect of acidification by acidic mine wastes on Cu solubility and on root elongation of barley (Hordeum vulgare L.). Three contrasting substrates (two soils and a commercial sand) and two acidic, Cu-rich mine wastes (oxidized tailings [OxT] and smelter dust [SmD]) were selected as experimental materials. Substrates were spiked with a fixed amount of either SmD or OxT, and the pH of experimental mixtures was then modified in the range of 4.0 to 6.0 and 7.0 using PIPES (piperazine-1,4-bis(2-ethanesulfonic acid)), MES (2-(N-morpholino)ethanesulfonic acid), and MOPS (3-(N-Morpholino)-propanesulfonic acid) buffers. Chemical (pore-water Cu and pH) and toxicological (root length of barley plants) parameters were determined for experimental mixtures. Addition of SmD and OxT to substrates resulted in acidification (0.11-1.16 pH units) and high levels of soluble Cu and Zn. Neutralization of experimental mixtures with MES (pH 6.0) and MOPS (pH 7.0) buffers resulted in a marked decrease in soluble Cu and Zn, but the intensity of the effect was substrate-dependent. Adjustment of soil pH above the range normally considered to be toxic to plants (pH in water extract, > 5.5) significantly reduced metal toxicity in barley, but phytotoxicity was not completely eliminated. The present results stress the importance of considering confounding effects on derivation of toxicity thresholds to plants when using laboratory phytotoxicity tests. PMID:19480535

  6. Linking the distribution of (210)Po and (210)Pb with plankton community along Line P, Northeast Subarctic Pacific.

    PubMed

    Choi, Hiu Yan; Stewart, Gillian M; Lomas, Michael W; Kelly, Roger P; Moran, S Bradley

    2014-12-01

    Depth profiles of (210)Po and (210)Pb activity and phytoplankton and zooplankton abundance were collected during two cruises along the Canadian time-series Line P in the Northeast Subarctic Pacific (ranging from 48o39 N to 50o00 N and 126o40 W to 145o00 W) in August 2010 and February 2011 to evaluate connections between the planktonic community and distributions of these radionuclides in the upper 500 m of the water column. Statistical analysis indicates that (210)Po is more effectively removed from the surface ocean when large (>0.1 mg ind(-1) dry wt) zooplankton dominate, and is less effectively scavenged when the picoplankton Synechococcus is present at high concentrations (>1 × 10(5) cells ml(-1)). While the zooplankton field data are consistent with previous lab studies and field observations, the phytoplankton results seem to conflict with recent evidence that small cells may contribute significantly to export in other oligotrophic regions. Differences in ecosystem mechanisms between the Subarctic Pacific and other oligotrophic systems that limit the contribution of small cells to sinking flux remain to be identified. PMID:24629375

  7. 210Pb-derived chronology in sediment cores evidencing the anthropogenic occupation history at Corumbataí River basin, Brazil

    NASA Astrophysics Data System (ADS)

    Bonotto, D. M.; de Lima, J. L. N.

    2006-07-01

    Activity profiles of excess 210Pb combined with chemical data determined in two sediment cores from Corumbataí River basin, São Paulo State, Brazil, provided new insights into the reconstruction of historical inputs of anthropogenic constituents, contributing to improving management strategies of the hydrological resources in the basin since most of the municipalities extensively utilize the waters of Corumbataí River and tributaries for drinking purposes, among other uses. Excellent significant relationships between loss on ignition (LOI) and organic matter were found for sediments of both analyzed profiles. Silica was found to be inversely related to organic matter at both analyzed profiles: its decrease accompanied an increase in 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, MnO, and TiO2. It was possible to identify the role of organic matter on adsorption of several oxides/elements in the core sediments profiles. Apparent sediment mass accumulation rates corresponding to 224 and 802 mg cm-2 year-1 were obtained, and are compatible with field evidence, indicating a higher value associated with sand mining activities interfering with the natural/normal sedimentation process, due to modifications of the channel drainage.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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

  10. 210Pb and 210Po, manganese and iron cycling across the O2/H2S interface of a permanently anoxic fjord: Framvaren, Norway

    USGS Publications Warehouse

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

    1999-01-01

    Vertical profiles of dissolved and particulate 210Po and 210b 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, 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.

  11. 230Th/232Th activity ratios as a chronological marker complementing 210Pb dating in an estuarine system affected by industrial releases.

    PubMed

    San Miguel, E G; Bolívar, J P; García-Tenorio, R; Martín, J E

    2001-01-01

    The main purpose of this research is to show the usefulness of the 230Th/232Th activity ratios as a chronological marker that can be helpful in the dating of sediment cores collected from an estuarine system located in the south west of Spain highly polluted by wastes from fertilizer plants. These wastes, being released for 30 years, and enriched in radionuclides from the uranium series including 210Pb, invalidate the application of the 210Pb dating technique in full extent to the sediment cores collected in this estuary. However, the evaluation and the interpretation of both 210Pb and 230Th/232Th profiles allows the determination of average sedimentation rates in different parts of the cores, contaminated and noncontaminated zone, that agree in the case analysed in this research. Through this approach, a confident chronology covering the last century, which is essential to analyse and reconstruct the historical evolution of other pollutants in this heavily contaminated system can be established. PMID:11291442

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

    PubMed

    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 < 0.05) decreased As concentrations in 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. An estimate of hydrothermal fluid residence times and vent chimney growth rates based on 210Pb Pb ratios and mineralogic studies of sulfides dredged from the Juan de Fuca Ridge

    USGS Publications Warehouse

    Kadko, D.; Koski, R.; Tatsumoto, M.; Bouse, R.

    1985-01-01

    The 210Pb Pb ratios across two sulfide samples dredged from the Juan de Fuca Ridge are used to estimate the growth rate of the sulfide material and the residence time of the hydrothermal fluid within the oceanic crust from the onset of basalt alteration. 210Pb is added to the hydrothermal fluid by two processes: (1) high-temperature alteration of basalt and (2) if the residence time of the fluid is on the order of the 22.3-year half-life of 210Pb, by in-situ growth from 222Rn (Krishnaswami and Turekian, 1982). Stable lead is derived only from the alteration of basalt. The 210Pb Pb ratio across one sample was ??? 0.5 dpm/10-6 g Pb, and across the other it was ??? 0.4 dpm/10-6 g Pb. These values are quite close to the 238U Pb ratios of basalts from the area, suggesting that the residence time of the hydrothermal fluid from the onset of basalt alteration is appreciably less than the mean life of 210Pb, i.e., the time required for ingrowth from the radon. An apparent growth rate of 1.2 cm/yr is derived from the slope of the 210Pb Pb curve for one of the samples. This is consistent with its mineralogy and texture which suggest an accretionary pattern of development. There is no obvious sequential growth pattern, and virtually no gradient in 210Pb Pb across the second sample. This is consistent with alteration of the original 210Pb Pb distribution by extensive remobilization reactions which are inferred from the mineralogic and textural relationships of the sample. ?? 1985.

  14. Duration of gas accumulation before the 2010 Eyjafjallajökull eruption constrained by 210Po-210Pb-226Ra disequilibria

    NASA Astrophysics Data System (ADS)

    Sigmarsson, Olgeir; Gauthier, Pierre-Jean; Condomines, Michel

    2014-05-01

    Excess gas phase in magmas erupting explosively is well known world-wide. However, the origin of this gas phase, in excess of what can be dissolved in the erupting magma at depth, and the duration of gas accumulation, is less well defined. The 2010 mildly explosive eruption at Eyjafjallajökull, Iceland, produced mingled tephra of benmoreiitic and trachytic composition whereas alkali basalt (MgO > 8 %) was emitted during the preceding flank eruption. The silicic tephra of the first explosive phase is composed of three glass types, alkaline rhyolite, mixed benmoreiite, and evolved basalt (MgO < 5 %). The rhyolitic glass is indistinguishable from tephra glass composition emitted during the penultimate eruption of Eyjafjallajökull in 1821-23 AD (Sigmarsson et al., 2011). Tephra from the first explosive phase, emitted on 15 and 17 April, had large 210Po in excess of 210Pb ((210Po/210Pb)0 as high as 2!) and a small, but significant, 210Pb excess over its parent 226Ra ((210Pb/226Ra)0= 1.05 and 1.04, respectively). These excesses suggest rapid accumulation of Po and Rn together with the major gas species in the residual rhyolitic magma from the 1821-23 eruption. The gas most likely originates from the basalt recharge that eventually provoked the eruption. Basalts emitted a month earlier during the flank eruption at Fimmvörðuháls lost all their Po upon eruption and had (210Po/210Pb)0 equal to 0). From a simple model of radon and polonium degassing and accumulation, the mass of basalt magma degassing over the mass of silicic magma accumulating the excess gas can be calculated. Moreover, the duration of gas accumulation can be shown to be close to 300 days. This duration suggests that gas was liberated from the basaltic magma since June 2009, a month that corresponds to the initial seismic swarm beneath Eyjafjallajökull preceding the explosive eruption of 14 April 2010.

  15. Incorporation of {sup 210}Pb and {sup 210}Po to Poultry through the Addition of Dicalcium Phosphate (DCP) to the Diet

    SciTech Connect

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

    2008-08-07

    Due to the replacement of calcium by uranium in the phosphorite, sedimentary phosphate rock contains high concentrations of {sup 238}U (i.e. from 1500 Bq{center_dot}kg{sup -1} in Morocco to 4000 Bq{center_dot}kg{sup -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 10{sup 3} Bq{center_dot}kg{sup -1} of {sup 238}U and some of its decay chain daughters. In particular, due to its radiological implications, the presence of {sup 210}Pb and {sup 210}Po 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 {sup 210}Pb and {sup 210}Po. 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 {sup 210}Pb were 0.93, 101.4 and 51.2 Bq{center_dot}kg{sup -1}; whereas concentrations of {sup 210}Po were 0.92, 74 and 36 Bq{center_dot}kg{sup -1} of food for diets A, B and C, respectively. Accumulation of {sup 210}Pb and {sup 210}Po 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 {sup 210}Pb and {sup 210}Po 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.

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

    SciTech Connect

    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.

  17. Sterilization affects soil organic matter chemistry and bioaccumulation of spiked p,p'-DDE and anthracene by earthworms.

    PubMed

    Kelsey, Jason W; Slizovskiy, Ilya B; Peters, Richard D; Melnick, Adam M

    2010-06-01

    Laboratory experiments were conducted to assess the effects of soil sterilization on the bioavailability of spiked p,p'-DDE and anthracene to the earthworms Eisenia fetida and Lumbricus terrestris. Physical and chemical changes to soil organic matter (SOM) induced by sterilization were also studied. Uptake of both compounds added after soil was autoclaved or gamma irradiated increased for E. fetida. Sterilization had no effect on bioaccumulation of p,p'-DDE by L. terrestris, and anthracene uptake increased only in gamma-irradiated soils. Analyses by FT-IR and DSC indicate sterilization alters SOM chemistry and may reduce pollutant sorption. Chemical changes to SOM were tentatively linked to changes in bioaccumulation, although the effects were compound and species specific. Artifacts produced by sterilization could lead to inaccurate risk assessments of contaminated sites if assumptions derived from studies carried out in sterilized soil are used. Ultimately, knowledge of SOM chemistry could aid predictions of bioaccumulation of organic pollutants. PMID:20227150

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

    NASA Astrophysics Data System (ADS)

    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) and particulate (>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

  19. Toxicity in lead salt spiked soils to plants, invertebrates and microbial processes: Unraveling effects of acidification, salt stress and ageing reactions.

    PubMed

    Smolders, Erik; Oorts, Koen; Peeters, Sofie; Lanno, Roman; Cheyns, Karlien

    2015-12-01

    The fate and effects of toxic trace metals in soil freshly spiked soluble metal salts do not mimic those of metals in the field. This study was set up to test the magnitude of effects of salinity, acidification, and ageing on toxicity of lead (Pb) to plants, invertebrates and soil microbial processes. Three soils were spiked with Pb2+ salts up to a concentration of 8000 mg Pb/kg and were tested either after spiking, after soil leaching followed by pH correction, or after a 5-year outdoor ageing period with free drainage followed by pH correction. Soil solution ionic strength exceeded 150 mmol/L in soils tested directly after spiking and this decreased partially after leaching and returned back to background values after 5-year outdoor equilibration. Chronic toxicity to two plants, two invertebrates, and three microbial endpoints was consistently found in all spiked soils that were not leached. This toxicity significantly decreased or became absent after 5 years of ageing in 19 of the 20 toxicity tests by a factor 8 (median factor; range: 1.4->50), measured by the factor increase of total soil Pb dose required to induce 10% inhibition. The toxicity of Pb in leached soils was intermediate between the other two treatments. The lowest detectable chronic thresholds (EC10) in aged soils ranged 350-5300 mg Pb/kg. Correlation analysis, including data of Pb2+ speciation in soil solution, suggests that reduced ionic strength rather than acidification or true ageing is the main factor explaining the soil treatment effects after spiking. It is suggested that future toxicity studies should test fine PbO powder as a relevant source for Pb in soils to exclude the confounding salt effects. PMID:26218561

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

    PubMed

    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

  1. Constraints from 210Pb and 7Be on wet deposition and transport in a global three-dimensional chemical tracer model driven by assimilated meteorological fields

    NASA Astrophysics Data System (ADS)

    Liu, Hongyu; Jacob, Daniel J.; Bey, Isabelle; Yantosca, Robert M.

    2001-06-01

    The atmospheric distributions of the aerosol tracers 210Pb and 7Be are simulated with a global three-dimensional model driven by assimilated meteorological observations for 1991-1996 from the NASA Goddard Earth Observing System (GEOS1). The combination of terrigenic 210Pb and cosmogenic 7Be provides a sensitive test of wet deposition and vertical transport in the model. Our simulation of moist transport and removal includes scavenging in wet convective updrafts (40% scavenging efficiency per kilometer of updraft), midlevel entrainment and detrainment, first-order rainout and washout from both convective anvils and large-scale precipitation, and cirrus precipitation. Observations from surface sites in specific years are compared to model results for the corresponding meteorological years, and observations from aircraft missions over the Pacific are compared to model results for the days of the flights. Initial simulation of 7Be showed that cross-tropopause transport in the GEOS1 meteorological fields is too fast by a factor of 3-4. We adjusted the stratospheric 7Be source to correct the tropospheric simulation. Including this correction, we find that the model gives a good simulation of observed 210Pb and 7Be concentrations and deposition fluxes at surface sites worldwide, with no significant global bias and with significant success in reproducing the observed latitudinal and seasonal distributions. We achieve several improvements over previous models; in particular, we reproduce the observed 7Be minimum in the tropics and show that its simulation is sensitive to rainout from convective anvils. Comparisons with aircraft observations up to 12-km altitude suggest that cirrus precipitation could be important for explaining the low concentrations in the middle and upper troposphere.

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

    PubMed

    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

  3. Scavenging of ex 234Th, ex 230Th, and ex 210Pb by particulate matter in the water column of the California Continental Margin

    NASA Astrophysics Data System (ADS)

    Shaw, Timothy J.; Smoak, Joseph M.; Lauerman, Lynn

    The accumulation of ex 230Th, organic carbon and total mass at Station M (a 4100-m site 220 Km off Central California) is not supported by sediment trap-collected fluxes. The flux of ex 230Th to sediment traps only accounts for 10% of the ex 230Th accumulation in sediments. The accumulation of ex 230Th in sediments exceeds water column production by a factor of 20. This discrepancy is reconciled by the vertical flux of very large aggregate flocs, which are not efficiently sampled by sediment traps. This process was examined through measurement of ex 234Th, ex 210Pb, and ex 230Th on sediment trap material, large aggregate flocs and surface sediments. Aggregate flocs and sediments were collected during two cruises with the submersible Alvin during major floc deposition events in August and September of 1994. Sediment trap material was analyzed for the summer/fall 1994 and the winter/spring of 1995. Our results indicate that a single floc deposition event may exceed the integrated annual sediment trap flux for organic carbon, mass and ex 230Th at Station M. Sediment trap flux data for ex 210Pb and ex 230Th, as well as lithogenic material (as Ti), suggest seasonality in their water column inventories. Seasonality implies residence times on the order of one-year or less for the water column inventories of ex 210Pb and ex 230Th at Station M. Bloom-induced floc deposition events represent an important mechanism for removal of suspended material, organic carbon and dissolved radionuclides in the waters of the California continental margin.

  4. 210Pb and 210Po Abundances in Dacites Erupted May, 2003 From Anatahan Volcano: Implications for the Time-scales of Magma Generation and Degassing

    NASA Astrophysics Data System (ADS)

    Reagan, M. K.; Matthew, W.; Brian, H.

    2003-12-01

    Six samples of dacite pumice and scoria erupted in May, 2003 and collected from a number of sites around Anathan by Tobias Fischer and David Hilton were analyzed for 210Po activities on three occasions between early June and the time of this writing. With two exceptions, all scoria and pumice samples have 210Po activities that plot on a single growth curve indicating initial (210Po)=0.15 +/-0.07 (1σ ) dpm/g and (210Pb)=1.08+/-0.20 dpm/g. More precise values for these initial activities will be presented at the meeting after further analyses are performed in November. Preliminary alpha spectrometry analyses for U and Th, and ICPMS analyses distributed by Terry Plank suggest that the average (238U) is about 0.53 dpm/g. Equilibrium (228Th)/( 232Th) ratios indicate that these samples do not have excess 228Ra. Assuming that (210Pb )< (226Ra) because of minor degassing of 210Pb (see Gauthier and Condomines, 1999, EPSL, v. 172), the degassing efficiency factor for 210Po is greater than or equal to about 0.85, which is identical to the value calculated for a basaltic andesitic lava from Arenal volcano in Costa Rica (Gill et al., 1985, GRL, v. 12). This is surprising, as the May 10 plinian eruption of Anatahan should have resulted in more closed-system degassing than a lava eruption. This and the similar 210Po values for the scoria and pumice samples suggest that the shallow-level degassing history has little impact on the efficiency of polonium degassing. The scoria and pumice samples from sample 8-1e both have significant excesses of 210Po over the calculated initial (210Pb) value for the other samples. These excesses were partially leachable, indicating that 210Po was sublimated onto these samples, and that these ejecta resided in the vent before being ejected and redeposited The high inferred (226Ra)/( 230Th) for the Anatahan dacites despite the nearly equilibrium (238U)/( 230Th) value measured for one sample contrasts with the values for these ratios in more mafic

  5. Effects and bioavailability of 2,4,6-trinitrotoluene in spiked and field-contaminated soils to indigenous microorganisms

    SciTech Connect

    Gong, P.; Siciliano, S.D.; Greer, C.W.; Paquet, L.; Hawari, J.; Sunahara, G.I.

    1999-12-01

    The response of potential nitrification activity (PNA), nitrogen-fixation activity (NFA), and dehydrogenase activity (DHA) in soil to 2,4,6-trinitrotoluene (TNT) was assessed. Two garden soils of contrasting texture were spiked with TNT. Soil microbial activities and TNT residues were analyzed 1 week later. The estimated IC50 ranged from 39 to 533 mg/kg of the acetonitrile-extractable (AE) TNT, depending on indicators and soils. The lowest LOEC (lowest-observed-effect concentration) was 1 mg AE TNT/kg. Field soil was collected from three known contaminated sites in an abandoned TNT manufacturing facility. Microbial toxicity significantly correlated to TNT levels in these soils. The LOEC and NOEC (no-observed-effect concentration) values were site and indicator specific, with the lowest LOEC being 1 mg AE TNT/kg and the lowest NOEC being 0.4 mg AE TNT/kg. The IC50 of the pooled field samples was 51 mg AE TNT/kg for PNA or 157 mg AE TNT/kg for DHA. These results indicate that microbial responses were consistent and comparable between the laboratory and the field and that TNT could significantly inhibit soil microbial activities at very low levels. Both AE TNT and deionized water-extractable (DW) TNT concentrations correlated well with microbial toxicity, but AE TNT provided a better evaluation of TNT bioavailability than did DW TNT.

  6. Examining (239+240)Pu, (210)Pb and historical events to determine carbon, nitrogen and phosphorus burial in mangrove sediments of Moreton Bay, Australia.

    PubMed

    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

  7. Sediment accumulation, stratigraphic order, and the extent of time-averaging in lagoonal sediments: a comparison of 210Pb and 14C/amino acid racemization chronologies

    NASA Astrophysics Data System (ADS)

    Kosnik, Matthew A.; Hua, Quan; Kaufman, Darrell S.; Zawadzki, Atun

    2015-03-01

    Carbon-14 calibrated amino acid racemization (14C/AAR) data and lead-210 (210Pb) data are used to examine sediment accumulation rates, stratigraphic order, and the extent of time-averaging in sediments collected from the One Tree Reef lagoon (southern Great Barrier Reef, Australia). The top meter of lagoonal sediment preserves a stratigraphically ordered deposit spanning the last 600 yrs. Despite different assumptions, the 210Pb and 14C/AAR chronologies are remarkably similar indicating consistency in sedimentary processes across sediment grain sizes spanning more than three orders of magnitude (0.1-10 mm). Estimates of long-term sediment accumulation rates range from 2.2 to 1.2 mm yr-1. Molluscan time-averaging in the taphonomically active zone is 19 yrs, whereas below the depth of final burial (~15 cm), it is ~110 yrs/5 cm layer. While not a high-resolution paleontological record, this reef lagoon sediment is suitable for paleoecological studies spanning the period of Western colonization and development. This sedimentary deposit, and others like it, should be useful, albeit not ideal, for quantifying anthropogenic impacts on coral reef systems.

  8. Air mass origin and its influence on radionuclide activities ( 7Be and 210Pb) in aerosol particles at a coastal site in the western Mediterranean

    NASA Astrophysics Data System (ADS)

    Dueñas, C.; Orza, J. A. G.; Cabello, M.; Fernández, M. C.; Cañete, S.; Pérez, M.; Gordo, E.

    2011-07-01

    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 Málaga (36° 43' 40″ N; 4° 28' 8″ W) for the period 2000-2006 were used to obtain the relationships between radionuclide activities and airflow patterns by comparing the data grouped by air mass trajectory clusters. The average concentration values of 7Be and 210Pb over the 7 year period have been found to be 4.6 and 0.58 mBq m -3, respectively, with mean aerosol mass concentration of 53.6 μg m -3. The identified air flow types arriving at Málaga reflect the transitional location of the Iberian Peninsula and show significant differences in radionuclide activities. Air concentrations of both nuclides and the aerosol mass concentration are controlled predominantly by the synoptic scenarios leading to the entrance of dust-laden continental flows from northern Africa and the arrival of polar maritime air masses, as implied by the strong correlations found between the monthly frequencies of the different air masses and the specific activities of both radionuclides. Correlations between activity concentrations and precipitation are significant though lower than with air masses.

  9. Influence of compost amendment on pyrene availability from artificially spiked soil to two subspecies of Cucurbita pepo.

    PubMed

    Kobayashi, Takayuki; Navarro, Ronald R; Tatsumi, Kenji; Iimura, Yosuke

    2008-10-01

    The dissolved organic matter (DOM) fraction of soil organic matter (SOM) may positively contribute to polycyclic aromatic hydrocarbons (PAHs) bioavailability. This work investigated the effects of DOM-rich and PAHs-free compost amendment on the plant uptake of pyrene. Two subspecies of Cucurbita pepo (ssp. pepo cv. Raven and ssp. texana cv. Sunray) were grown for three weeks in a spiked soil containing 83.9 mg kg(-1) pyrene under four different treatments; inorganic fertilizer (IF) alone, 15% (v/v) mixed gardening compost with IF (MX15%+IF), MX30% alone, and no fertilization (NF). Equilibrium pyrene desorptions from a spiked soil (104 mg kg(-1)) under different concentrations (35-590 mg-C L(-1)) of DOM extracts derived from two types of composts including MX and cow manure were also conducted. After harvest, the decrease in the pyrene concentration of the soil ranged from 46-65% for the different treatments. The total dry biomass for both plants was highest under MX15%+IF. The bioconcentration factors of pyrene for both also tended to decrease with increasing MX dose from 15% to 30%. However, the total uptakes of pyrene with IF and MX15%+IF were not statistically different (36.7 and 33.7 microg for Raven, and 5.20 and 7.90 microg for Sunray, respectively). These values were around 100% higher than that with NF (17.4 microg for Raven and 2.0 microg for Sunray). The pyrene desorption data confirmed the ability of DOM to associate with pyrene as indicated by its increase in apparent water solubility. On the basis of these results, MX application at 15% (v/v) does not significantly reduce the phytoextraction of pyrene due to the enhancement of plant growth as well as the possible contribution of DOM fractions to pyrene bioavailability. The application of compost may not pose serious concerns regarding the efficiency of phytoremediation of PAHs-polluted soil. PMID:18632137

  10. Accumulation of 2,4-dinitroanisole in the earthworm Eisenia fetida from chemically spiked and aged natural soils.

    PubMed

    Lotufo, Guilherme R; Coleman, Jessica G; Harmon, Ashley R; Chappell, Mark A; Bednar, Anthony J; Russell, Amber L; Smith, Jared C; Brasfield, Sandra M

    2016-07-01

    An initiative within the US military is targeting the replacement of traditional munitions constituents with insensitive munitions to reduce the risk of accidental detonation. The bioavailability and bioaccumulative potential of the insensitive munitions compound 2,4-dinitroanisole (DNAN) to Eisenia fetida was assessed in soils with different geochemical characteristics. Prior to exposure, soils were chemically spiked with DNAN and aged for 1 wk or 29 wk. Transformation products 2- and 4-amino-nitroanisole (2A-4NAN and 4A-2NAN) occurred in aged soils and their porewater but never at concentrations higher than the residual DNAN. The sum of DNAN, 2A-4NAN, and 4A-2NAN (sumDNAN) in soil decreased with aging, likely by irreversible binding. Both clay and organic matter contents of the soil appeared to affect the bioavailability of DNAN. The sumDNAN body residues of earthworms approached apparent steady state after 1 d and remained relatively constant through to day 7. Higher concentrations of 2A-4NAN and 4A-2NAN measured in worm tissues relative to those in soil suggest reductive transformation of DNAN in the tissues. Mean bioaccumulation factors (ratio of tissue to soil concentrations) varied from 1.2 to 4.3, whereas mean bioconcentration factors (ratio of tissue to porewater concentrations) ranged from 1.4 to 3.2. Porewater seems to play a significant role in the accumulation of DNAN in earthworms, consistent with equilibrium partitioning theory. The concentration of DNAN in soil porewater could serve as an indicator of bioavailability as well as a predictor of the concentration of that compound in earthworms. Environ Toxicol Chem 2016;35:1835-1842. Publlished 2015 SETAC. This article is a US Government work, and as such, is in the public domain in the United States of America. PMID:26666709

  11. 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.

    PubMed

    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

  12. Two-dimensional model for soil electrokinetic remediation of heavy metals. Application to a copper spiked kaolin.

    PubMed

    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

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

    SciTech Connect

    Hamilton, T.; Fowler, S.; Miquel, J.C.; La Rosa, J.

    1996-04-01

    A central goal of the ELNA project is to assess the carbon assimilation capacity of the Northern Adriatic Sea. This requires fundamental quantitative information on budgets and sinks of organic carbon. Any change in carbon production in the water column should be reflected in the underlying sediments. Moreover, the fraction of particulate organic carbon reaching the sea floor which is subsequently preserved in the sediment will be strongly coupled to sediment accumulation and mixing. In this study a series of box cores were collected in order to characterize a hypothetical eutrophication gradient extending from the Po River outflow region in the north down to the shallow meso-Adriatic depression (Jabuka Pit). The main tasks assigned to IAEA-MEL were to provide {sup 210}Pb derived sedimentation and dry-mass accumulation rates and to examine the possible correlations between sedimentary processes, the deposition and preservation of sedimentary organic carbon and pelagic primary productivity.

  14. (210)Pb and composition data of near-surface sediments and interstitial waters evidencing anthropogenic inputs in Amazon River mouth, Macapá, Brazil.

    PubMed

    Nery, José Reinaldo Cardoso; Bonotto, Daniel Marcos

    2011-04-01

    Activity profiles of excess (210)Pb determined in three sediment cores from Amazon River mouth, Macapá 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 Amapá 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 Amapá 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 Na(2)O, K(2)O, CaO, MgO, Al(2)O(3), P(2)O(5), Fe(2)O(3) 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 (210)Pb 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, Amapá 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. PMID:21353731

  15. 210Pb, 137Cs and 239,240Pu in East China Sea Sediments: Sources, Pathways and Budgets of Sediments and Radionuclides

    NASA Astrophysics Data System (ADS)

    Su, C.; Huh, C.

    2001-05-01

    Profiles of 210Pb, 137Cs and 239,240Pu measured in eighty-three sediment cores collected from various sedimentary regimes in the East China Sea were analyzed to elucidate the sources, routes and budgets of sediments as well as these radionuclides. Distributions of sedimentation rates and nuclide inventories reveal alongshore transport of sediments, 137Cs and 239,240Pu from the mouth of the Yangtze River toward the south, and it is largely confined to the inner-shelf area (water depth <70 m). Mass balance calculations of the budgets of nuclides suggest that the East China Sea is a sink for the particle-reactive 210Pb and 239,240Pu, with up to 20% of their sedimentary budgets supplied via boundary scavenging. In contrast, due to lower affinity of 137Cs for particles and rapid turnover of the shelf water, the East China Sea serves as a source for 137Cs. About two-thirds of the cumulative inputs of 137Cs have been transported out of the East China Sea, leaving the remaining one-third in sediments and the overlying water column. As for the sediment budget, mass balance can not be established due to a shortfall in sediment supply of more than 30% based on a comparison between input terms documented thus far and the sedimentation flux derived from this study. It could be that our sedimentation rates are overestimated, and/or that long-distance transport from the Yellow River's dispersal system to the ECS is underestimated previously. Alternatively, there is no reason to expect the attainment of equilibrium between sediment input and output in the East China Sea on decadal time scales.

  16. Asymmetric flow field-flow fractionation of manufactured silver nanoparticles spiked into soil solution.

    PubMed

    Koopmans, G F; Hiemstra, T; Regelink, I C; Molleman, B; Comans, R N J

    2015-05-01

    Manufactured metallic silver nanoparticles (AgNP) are intensively utilized in consumer products and this will inevitably lead to their release to soils. To assess the environmental risks of AgNP in soils, quantification of both their concentration and size in soil solution is essential. We developed a methodology consisting of asymmetric flow field-flow fractionation (AF4) in combination with on-line detection by UV-vis spectroscopy and off-line HR-ICP-MS measurements to quantify the concentration and size of AgNP, coated with either citrate or polyvinylpyrrolidone (PVP), in water extracts of three different soils. The type of mobile phase was a critical factor in the fractionation of AgNP by AF4. In synthetic systems, fractionation of a series of virgin citrate- and PVP-coated AgNP (10-90 nm) with reasonably high recoveries could only be achieved with ultrahigh purity water as a mobile phase. For the soil water extracts, 0.01% (w:v) sodium dodecyl sulfate (SDS) at pH 8 was the key to a successful fractionation of the AgNP. With SDS, the primary size of AgNP in all soil water extracts could be determined by AF4, except for PVP-coated AgNP when clay colloids were present. The PVP-coated AgNP interacted with colloidal clay minerals, leading to an overestimation of their primary size. Similar interactions between PVP-coated AgNP and clay colloids can take place in the environment and facilitate their transport in soils, aquifers, and surface waters. In conclusion, AF4 in combination with UV-vis spectroscopy and HR-ICP-MS measurements is a powerful tool to characterize AgNP in soil solution if the appropriate mobile phase is used. PMID:25798868

  17. Do drying and rewetting cycles modulate effects of sulfadiazine spiked manure in soil?

    PubMed

    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 with Dactylis glomerata L. 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 of sul1, sul2, intI1 ,intI2, qacE+qacEΔ1, traN and korB genes 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

  18. Ground water contamination with (238)U, (234)U, (235)U, (226)Ra and (210)Pb from past uranium mining: cove wash, Arizona.

    PubMed

    Dias da Cunha, Kenya Moore; Henderson, Helenes; Thomson, Bruce M; Hecht, Adam A

    2014-06-01

    The objectives of the study are to present a critical review of the (238)U, (234)U, (235)U, (226)Ra and (210)Pb levels in water samples from the EPA studies (U.S. EPA in Abandoned uranium mines and the Navajo Nation: Red Valley chapter screening assessment report. Region 9 Superfund Program, San Francisco, 2004, Abandoned uranium mines and the Navajo Nation: Northern aum region screening assessment report. Region 9 Superfund Program, San Francisco, 2006, Health and environmental impacts of uranium contamination, 5-year plan. Region 9 Superfund Program, San Franciso, 2008) and the dose assessment for the population due to ingestion of water containing (238)U and (234)U. The water quality data were taken from Sect. "Data analysis" of the published report, titled Abandoned Uranium Mines Project Arizona, New Mexico, Utah-Navajo Lands 1994-2000, Project Atlas. Total uranium concentration was above the maximum concentration level for drinking water (7.410-1 Bq/L) in 19 % of the water samples, while (238)U and (234)U concentrations were above in 14 and 17 % of the water samples, respectively. (226)Ra and (210)Pb concentrations in water samples were in the range of 3.7 × 10(-1) to 5.55 × 102 Bq/L and 1.11 to 4.33 × 102 Bq/L, respectively. For only two samples, the (226)Ra concentrations exceeded the MCL for total Ra for drinking water (0.185 Bq/L). However, the (210)Pb/(226)Ra ratios varied from 0.11 to 47.00, and ratios above 1.00 were observed in 71 % of the samples. Secular equilibrium of the natural uranium series was not observed in the data record for most of the water samples. Moreover, the (235)U/(total)U mass ratios ranged from 0.06 to 5.9 %, and the natural mass ratio of (235)U to (total)U (0.72 %) was observed in only 16 % of the water samples, ratios above or below the natural ratio could not be explained based on data reported by U.S. EPA. In addition, statistical evaluations showed no correlations among the distribution of the radionuclide concentrations

  19. Chemometric treatment of multimode laser-induced fluorescence (LIF) data of fuel-spiked soils

    NASA Astrophysics Data System (ADS)

    Van Benthem, Mark H.; Mitchell, Ben C.; Gillispie, Gregory D.; St. Germain, Randy W.

    1996-11-01

    Field screening of fuel-contaminated soils using laser- induced fluorescence is a cost effective and timely method of characterizing contaminated sites. Data collected with laser-based screening tools are often extensive and difficult to interpret. Pattern recognition algorithms can be utilized to enable less highly trained personnel to identify contaminants. In this work, fluorescence intensity of various hydrocarbon fuels deposited on various soil types was measured as a function of emission wavelength and decay time, generating wavelength-time matrices. The data were arranged into a three mode array and subjected to trilinear decomposition (TLD). The results of the TLD were then utilized in pattern recognition schemes, specifically, linear discrimination and classification and hierarchical cluster analysis. Classification rates and clustering results indicate that these techniques can be very valuable tools in site characterization.

  20. Chemometric treatment of multimode laser-induced fluorescence (LIF) data of fuel-spiked soils

    SciTech Connect

    Van Benthem, M.H.; Mitchell, B.C.; Gillispie, G.D.; St. Germain, R.W.

    1996-12-31

    Field screening of fuel-contaminated soils using laser-induced fluorescence is a cost effective and timely method of characterizing contaminated sites. Data collected with laser-based screening tools are often extensive and difficult to interpret. Pattern recognition algorithms can be utilized to enable less highly trained personnel to identify contaminants. In this work, fluorescence intensity of various hydrocarbon fuels deposited on various soil types was measured as a function of emission wavelength and decay time, generating wavelength-time matrices (WTMs). The data were arranged into a three mode array and subjected to trilinear decomposition (TLD). The results of the TLD were then utilized in pattern recognition schemes, specifically, linear discrimination and classification and hierarchical cluster analysis. Classification rates and clustering results indicate that these techniques can be very valuable tools in site characterization.

  1. Application of a magnesium/co-solvent system for the degradation of polycyclic aromatic hydrocarbons and their oxygenated derivatives in a spiked soil.

    PubMed

    Elie, Marc R; Williamson, Robert E; Clausen, Christian A; Yestrebsky, Cherie L

    2014-12-01

    This study evaluates the capability, efficacy and practicality of a combined approach based on solvent extraction and chemical reduction to simultaneously degrade polycyclic aromatic hydrocarbons (PAHs) and their oxygenated derivatives (OPAHs) in spiked soil. The spiked soil was washed using a composite organic solvent consisting of ethanol and ethyl lactate (1:1, v/v) and then degradation of the extracted contaminants using zero-valent magnesium. The extraction conditions were optimized at 25 °C with solvent-soil ratio of 2:1 (v/w) and the ensuing degradation efficiency ranged from 79% to 88% for the OPAHs, and 66% to 87% for the PAHs after 24 h of reaction at pH of 6.1. The reductive degradation of the spiked contaminants followed pseudo-first-order kinetics; however, comparing the kinetic results of this study to soil-free studies, the degradation rates are significantly reduced. It can be inferred that extracted organic or inorganic components from the soil medium hinder the degradation process, possibly by reducing the reactivity of the activated metal. Furthermore, to our understanding, this study is the first report on the simultaneous degradation of these priority pollutants and their oxygenated derivatives. The experimental results encourage the application of this magnesium/co-solvent system for future pilot-scale remediation studies. PMID:25461950

  2. The effects of temperature and nitrogen and sulfur additions on carbon accumulation in a nutrient-poor boreal mire: Decadal effects assessed using 210Pb peat chronologies

    NASA Astrophysics Data System (ADS)

    Olid, Carolina; Nilsson, Mats B.; Eriksson, Tobias; Klaminder, Jonatan

    2014-03-01

    Boreal peatlands are a major long-term reservoir of atmospheric carbon (C) and play an important role in the global C cycle. It is unclear how C accumulation in peatlands responds to changing temperatures and nutrients (specifically, nitrogen and sulfur). In this study, we assessed how the C input rate and C accumulation rate in decadal old peat layers respond to increased air temperatures (+3.6°C) during the growing season and the annual additions of nitrogen (N) and sulfur (S) (30 and 20 kg ha-1 yr-1, respectively) over 12 years of field treatments in a boreal mire. An empirical mass balance model was applied to 210Pb-dated peat cores to evaluate changes in C inputs, C mass loss, and net C accumulation rates in response to the treatments. We found that (i) none of the treatments generated a significant effect on peat mass loss decay rates, (ii) C input rates were positively affected by N additions and negatively affected by S additions, (iii) the C accumulation rate in the uppermost (10 to 12 cm) peat was increased by N additions and decreased by S additions, and (iv) only air temperature significantly affected the main effects induced by N and S additions. Based on our findings, we argue that C accumulation rates in surface peat layers of nutrient-poor boreal mires can increase despite the predicted rise in air temperatures as long as N loads increase and acid atmospheric S remains low.

  3. Application of 210Pb-derived sedimentation rates and dinoflagellate cyst analyses in understanding Pyrodinium bahamense harmful algal blooms in Manila Bay and Malampaya Sound, Philippines.

    PubMed

    Sombrito, E Z; Bulos, A dM; Sta Maria, E J; Honrado, M C V; Azanza, Rhodora V; Furio, Elsa F

    2004-01-01

    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 seed bed. PMID:15245847

  4. Why would we use the Sediment Isotope Tomography (SIT) model to establish a 210Pb-based chronology in recent-sediment cores?

    PubMed

    Abril Hernández, José-María

    2015-05-01

    After half a century, the use of unsupported (210)Pb ((210)Pbexc) 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 (210)Pbexc 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. PMID:25725452

  5. Molecular level characterization of diatom-associated biopolymers that bind 234Th, 233Pa, 210Pb, and 7Be in seawater: A case study with Phaeodactylum tricornutum

    NASA Astrophysics Data System (ADS)

    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.

  6. Determination of (210)Pb and (226)Ra/(228)Ra in continental water using HIDEX 300SL LS-spectrometer with TDCR efficiency tracing and optimized α/β-discrimination.

    PubMed

    Eikenberg, J; Beer, H; Jäggi, M

    2014-11-01

    An analytical method for determination of (210)Pb, (226)Ra and (228)Ra is presented based on adsorption on 3M Empore RadDiscs, and measurement applying liquid scintillation spectrometry (LSC) after elution. The LSC measurement was performed with optimized α/β-discrimination and isotope standardization using the triple to double coincidence ratio (TDCR). The consistency of measurement results between radioactive parent-daughter pairs (210)Pb/(210)Bi, (226)Ra/(222)Rn and (228)Ra/(228)Ac was checked in long-term counting experiments and the influence ofinterference of in-growing daughters from (226)Ra into the β-spectrum of (228)Ra+(228)Ac was studied as well. Recommendations for optimized LSC (228)Ra measurement besides presence of (226)Ra are given. PMID:24637085

  7. Beryllium-7 and lead-210 chronometry of modern soil processes: The Linked Radionuclide aCcumulation model, LRC

    NASA Astrophysics Data System (ADS)

    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

  8. Bioaccessibility of arsenic and cadmium assessed for in vitro bioaccessibility in spiked soils and their interaction during the Unified BARGE Method (UBM) extraction.

    PubMed

    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

  9. Spiking solvent, humidity and their impact on 2,4-D and 2,4-DCP extractability from high humic matter content soils.

    PubMed

    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

  10. Hg Deposition to Lakes in Northern New England Inferred at Multiple Scales From 210Pb-Dated Sediment Cores

    NASA Astrophysics Data System (ADS)

    Kamman, N. C.; Engstrom, D.

    2004-05-01

    Mercury (Hg) contamination of aquatic systems is recognized to be a problem of global consequence, and Hg bioaccumulation poses significant risks to piscivorous animals and humans who consume gamefish. In order to quantify historical and current Hg deposition to the northern New England landscape, we dated and performed Hg analyses on sediments cores from various lakes at local and regional scales. In this presentation, we contrast results of three studies: a regional assessment of Hg deposition to the VT-NH landscape (10 lakes); a localized study of deposition to the Lye Brook Wilderness of southern VT (four lakes); and the first-ever dated assessment of sediment Hg deposition history for Lake Champlain (three sites + one adjacent inland lake). At the VT-NH scale, total Hg (HgT) fluxes to sediments ranged from 5 to 17 μ g.m-2.yr-1 during pre-industrial times, and from 21 to 83 μ g.m-2.yr-1 presently. Present-day HgT fluxes are between 2.1 to 6.9 times greater than pre-1850 fluxes, and atmospheric Hg deposition to the VT-NH region was estimated at 21 μ g.m-2.yr-1. This agrees well with measured HgT deposition, when re-evasion of Hg is accounted for. Hg fluxes to lake sediments have declined in recent decades, owing to reductions in atmospheric Hg deposition to the lake surfaces. In the high-elevation Lye Brook Wilderness landscape, baseline, peak, and present accumulations were higher than those estimated from the VT-NH dataset, a finding that highlights the roles of elevation, watershed size, and dissolved organic carbon export in mediating Hg transport. Available data from the Lake Champlain Basin show the influence of historical and current watershed sediment delivery due to land cultivation, and more recently to land-use conversion. These studies jointly indicate that watershed export of legacy Hg continues despite declines in present-day deposition rates, contributing to the impression that Hg retention by watershed soils has declined.

  11. 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

    NASA Astrophysics Data System (ADS)

    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.

  12. The effectiveness of ferrous iron and sodium dithionite for decreasing resin-extractable Cr(VI) in Cr(VI)-spiked alkaline soils.

    PubMed

    Cheng, Chia-Jung; Lin, Tzu-Huei; Chen, Chiou-Pin; Juang, Kai-Wei; Lee, Dar-Yuan

    2009-05-30

    Ferrous iron, Na(2)S(2)O(4), and a mixture of Fe(II) and Na(2)S(2)O(4) (4:1 mol/mol) were tested for their effectiveness for decreasing resin-extractable Cr(VI) in alkaline Cr(VI)-spiked soils. The results indicated that adding those reductants greatly decreased the amount of resin-extractable Cr(VI) when the application rate of reductants equaled the number of equivalents of dichromate added to the Cr(VI)-spiked soils. This was mainly as a result of the Cr(VI) reduction into Cr(III), as supported by the XANES spectra. Among the tested reductants, a mixture of Fe(II) and Na(2)S(2)O(4) was the most effective to decrease resin-extractable Cr(VI). The extent to which resin-extractable Cr(VI) and soil pH were decreased was affected by the pH of the reductants. Among the tested reductants at various pH, FeSO(4) at pH below 1 was the most effective in decreasing resin-extractable Cr(VI) in alkaline soils. However, the soil pH was the most decreased as well. On the other hand, the mixtures of ferrous iron and dithionite at a wide range of pH were all efficient (>70% efficiency) in decreasing resin-extractable Cr(VI). Moreover, the extent of the decrease in soil pH was much smaller than that by FeSO(4) (pH<1) alone, and thus the possibility of the Cr(III) hazard can be avoided. PMID:18824300

  13. Timing of degassing and plagioclase growth in lavas erupted from Mount St. Helens, 2004-2005, from 210Po-210Pb-226Ra disequilibria: Chapter 37 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Reagan, Mark K.; Cooper, Kari M.; Pallister, John S.; Thornber, Carl R.; Wortel, Matthew

    2008-01-01

    Disequilibrium between 210Po, 210Pb, and 226Ra was measured on rocks and plagioclase mineral separates erupted during the first year of the ongoing eruption of Mount St. Helens. The purpose of this study was to monitor the volatile fluxing and crystal growth that occurred in the weeks, years, and decades leading up to eruption. Whole-rock samples were leached in dilute HCl to remove 210Po precipitated in open spaces. Before leaching, samples had variable initial (210Po) values, whereas after leaching, the groundmasses of nearly all juvenile samples were found to have had (210Po) ≈ 0 when they erupted. Thus, most samples degassed 210Po both before and after the magmas switched from open- to closed-system degassing. All juvenile samples have (210Pb)/(226Ra) ratios within 2 δ of equilibrium, suggesting that the magmas involved in the ongoing eruption did not have strong, persistent fluxes of 222Rn in or out of magmas during the decades and years leading to eruption. These equilibrium values also require a period of at least a century after magma generation and the last significant differentiation of the Mount St. Helens dacites. Despite this, the elevated (210Pb)/(226Ra) value measured in a plagioclase mineral separate from lava erupted in 2004 suggests that a significant proportion of this plagioclase grew within a few decades of eruption. The combined dataset suggests that for most 2004-5 lavas, the last stage of open-system degassing of the dacite magmas at Mount St. Helens is confined to the period between 1-2 years and 1-2 weeks before eruption, whereas plagioclase large enough to be included in the mineral separate grew around the time of the 1980s eruption or earlier.

  14. Using unsupported lead-210 measurements to investigate soil erosion and sediment delivery in a small Zambian catchment

    NASA Astrophysics Data System (ADS)

    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. Is it clean or contaminated soil? Using petrogenic versus biogenic GC-FID chromatogram patterns to mathematically resolve false petroleum hydrocarbon detections in clean organic soils: a crude oil-spiked peat microcosm experiment.

    PubMed

    Kelly-Hooper, Francine; Farwell, Andrea J; Pike, Glenna; Kennedy, Jocelyn; Wang, Zhendi; Grunsky, Eric C; Dixon, D George

    2013-10-01

    The Canadian Council of Ministers of the Environment (CCME) reference method for the Canada-wide standard (CWS) for petroleum hydrocarbon (PHC) in soil provides chemistry analysis standards and guidelines for the management of contaminated sites. However, these methods can coextract natural biogenic organic compounds (BOCs) from organic soils, causing false exceedences of toxicity guidelines. The present 300-d microcosm experiment used CWS PHC tier 1 soil extraction and gas chromatography-flame ionization detector (GC-FID) analysis to develop a new tier 2 mathematical approach to resolving this problem. Carbon fractions F2 (C10-C16), F3 (C16-C34), and F4 (>C34) as well as subfractions F3a (C16-C22) and F3b (C22-C34) were studied in peat and sand spiked once with Federated crude oil. These carbon ranges were also studied in 14 light to heavy crude oils. The F3 range in the clean peat was dominated by F3b, whereas the crude oils had approximately equal F3a and F3b distributions. The F2 was nondetectable in the clean peat but was a significant component in crude oil. The crude oil–spiked peat had elevated F2 and F3a distributions. The BOC-adjusted PHC F3 calculation estimated the true PHC concentrations in the spiked peat. The F2:F3b ratio of less than 0.10 indicated PHC absence in the clean peat, and the ratio of greater than or equal to 0.10 indicated PHC presence in the spiked peat and sand. Validation studies are required to confirm whether this new tier 2 approach is applicable to real-case scenarios. Potential adoption of this approach could minimize unnecessary ecological disruptions of thousands of peatlands throughout Canada while also saving millions of dollars in management costs. PMID:23703885

  16. Soil erosion and sediment sources in an Ohio watershed using beryllium-7, cesium-137, and lead-210.

    PubMed

    Matisoff, Gerald; Bonniwell, Everett C; Whiting, Peter J

    2002-01-01

    Soil cores and suspended sediments were collected within the Old Woman Creek, Ohio (OWC) watershed following a thunderstorm and analyzed for 7Be, 137Cs, and 210Pb activities to compare the effects of till vs. no-till management on soil erosion and sediment yield. The upper reaches of the watershed draining tilled agricultural fields were disproportionately responsible for the majority of the suspended sediment load compared with lower in the watershed (2.0-7.0 metric tons/km2 [Mg/km2] vs. 1.2-2.6 Mg/km2). About 6 to 10 times more sediment was derived from the subbasins that are predominantly tilled (6.8-12.4 Mg/km2) compared with the subbasins undergoing no-till practices (0.5-1.1 Mg/km2). In undisturbed soils the 210Pb activities decreased with movement toward the bottom of the cores to the constant supported 210Pb value at a depth of about 10 cm. There was a subsurface maximum in 137Cs activity within the top 10 cm. In contrast, the 210Pb and 137Cs distributions in soils that are currently or were previously tilled were nearly homogeneous with depth, reflecting continuing or previous mixing by plowing. The activities of 210Pb and 7Be were linearly correlated and were higher in suspended sediments derived from no-till subbasins than those derived from tilled subbasins, indicating that the soil surface is the source of suspended sediment. This study demonstrates that no-till farming results in decreases in soil erosion and decreases in suspended sediment discharges and that those eroded sediments have a radionuclide signature corresponding to the tillage practice and the depth of erosion. PMID:11837444

  17. Combined effect of Cd and Pb spiked field soils on bioaccumulation, DNA damage, and peroxidase activities in Trifolium repens.

    PubMed

    Lanier, C; Bernard, F; Dumez, S; Leclercq, J; Lemière, S; Vandenbulcke, F; Nesslany, F; Platel, A; Devred, I; Cuny, D; Deram, A

    2016-01-01

    The present study was designed to investigate the combined effects of Cd and Pb on accumulation and genotoxic potential in white clover (Trifolium repens). For this purpose, T. repens was exposed to contaminated soils (2.5-20 mg kg(-1) cadmium (Cd), 250-2000 mg kg(-1) lead (Pb) and a mixture of these two heavy metals) for 3, 10 and 56 days. The resulting bioaccumulation of Cd and Pb, DNA damage (comet assay) and peroxidase activities (APOX and GPOX) were determined. The exposure time is a determinant factor in experiments designed to measure the influence of heavy metal contamination. The accumulation of Cd or Pb resulting from exposure to the two-metal mixture does not appear to depend significantly on whether the white clover is exposed to soil containing one heavy metal or both. However, when T. repens is exposed to a Cd/Pb mixture, the percentage of DNA damage is lower than when the plant is exposed to monometallic Cd. DNA damage is close to that observed in the case of monometallic Pb exposure. Peroxidase activity cannot be associated with DNA damage under these experimental conditions. PMID:26396009

  18. Use of fallout radionuclides ((7)Be, (210)Pb) to estimate resuspension of Escherichia coli from streambed sediments during floods in a tropical montane catchment.

    PubMed

    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

  19. The electromagnetic spike solutions

    NASA Astrophysics Data System (ADS)

    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.

  20. Low level measurements of natural radionuclides in soil samples around a coal-fired power plant

    NASA Astrophysics Data System (ADS)

    Rosner, G.; Bunzl, K.; Hötzl, H.; Winkler, R.

    1984-06-01

    To detect a possible contribution of airborne radioactivity from stack effluents to the soil radioactivity, several radionuclides in the soil around a coal-fired power plant have been determined. A plant situated in a rural region of Bavaria was selected to minimize contributions from other civilisatory sources. The soil sampling network consisted of 5 concentric circles with diameters between 0.4 and 5.2 km around the plant, 16 sampling points being distributed regularly on each circle. Radiochemical analysis techniques for 210Pb and 210Po in soil samples of several grams had to be developed. They include a wet dissolution procedure, simultaneous precipitation of lead and polonium as the sulfides, purification via lead sulfate, counting of the lead as the chromate in a low-level beta counter and alpha spectrometric determination of the 210Po in a gridded ionization chamber. The 238U, 226Ra, 232Th and 40K were counted by low level gamma spectrometry. Specific activities found were in the range of 0.7 to 2.0 pCi g -1 for 210Pb and 0.3 to 1.6 pCi g -1 for 226Ra. The distribution patterns of 210Po and 210Pb around the plant were found to be similar. They were different, however, from that of 226Ra. The highest 210Pb/ 226Ra activity ratio was 3.9 at a distance of 0.76 km SSE from the plant. Nevertheless, the evidence is not considered to be sufficient to attribute these observations unambiguously to plant releases.

  1. Monitoring spike train synchrony.

    PubMed

    Kreuz, Thomas; Chicharro, Daniel; Houghton, Conor; Andrzejak, Ralph G; Mormann, Florian

    2013-03-01

    Recently, the SPIKE-distance has been proposed as a parameter-free and timescale-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 eventlike firing patterns. Here we present a substantial improvement of this measure that 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 field data by monitoring the synchrony between neuronal spike trains during an epileptic seizure. Finally, the applicability of both the regular and the real-time SPIKE-distance to continuous data is illustrated on model electroencephalographic (EEG) recordings. PMID:23221419

  2. Temporal spike pattern learning

    NASA Astrophysics Data System (ADS)

    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 t0+τ(R) in response to the input spike received at time t0 . 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.

  3. Temporal spike pattern learning.

    PubMed

    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

  4. Spiking the Geomagnetic Field

    NASA Astrophysics Data System (ADS)

    Constable, C.; Davies, C. J.

    2015-12-01

    Geomagnetic field intensities corresponding to virtual axial dipole moments of up to 200 ZAm2, more than twice the modern value, have been inferred from archeomagnetic measurements on artifacts dated at or shortly after 1000 BC. Anomalously high values occur in the Levant and Georgia, but not in Bulgaria. The origin of this spike is believed to lie in Earth's core: however, its spatio-temporal characteristics and the geomagnetic processes responsible for such a feature remain a mystery. We show that a localized spike in the radial magnetic field at the core-mantle boundary (CMB) must necessarily contribute to the largest scale changes in Earth's surface field, namely the dipole. Even the limiting spike of a delta function at the CMB produces a minimum surface cap size of 60 degrees for a factor of two increase in paleointensity. Combined evidence from modern satellite and millennial scale field modeling suggests that the Levantine Spike is intimately associated with a strong increase in dipole moment prior to 1000 BC and likely the product of north-westward motion of concentrated near equatorial Asian flux patches like those seen in the modern field. New archeomagnetic studies are needed to confirm this interpretation. Minimum estimates of the power dissipated by the spike are comparable to independent estimates of the dissipation associated with the entire steady state geodynamo. This suggests that geomagnetic spikes are either associated with rapid changes in magnetic energy or strong Lorentz forces.

  5. Concentrations of 238U, 234U, 235U, 232Th, 230Th, 228Th, 226Ra, 228Ra, 224Ra, 210Po, 210Pb and 212Pb in drinking water in Italy: reconciling safety standards based on measurements of gross alpha and beta.

    PubMed

    Jia, Guogang; Torri, Giancarlo; Magro, Leandro

    2009-11-01

    Some important naturally occurring alpha- and beta-radionuclides in drinking water samples collected in Italy were determined and the radiological quality evaluated. The mean activity concentrations (mBqL(-1)) of the radionuclides in the water samples were almost in the order: 26+/-36 ((234)U)>21+/-30 ((238)U)>8.9+/-15 ((226)Ra)>4.8+/-6.3 ((228)Ra)>4.0+/-4.1 ((210)Pb)>3.2+/-3.7 ((210)Po)>2.7+/-1.2 ((212)Pb)>1.4+/-1.8 ((224)Ra)> 1.1+/-1.3 ((235)U)>0.26+/-0.39 ((228)Th)>0.0023+/-0.0009 ((230)Th)>0.0013+/-0.0006 ((232)Th). The mean estimated dose (microSvyr(-1)) to an adult from the water intake was in this order: 2.8+/-3.3 ((210)Po)>2.4+/-3.2 ((228)Ra)>2.1+/-2.1 ((210)Pb)>1.8+/-3.1 ((226)Ra)>0.94+/-1.30 ((234)U)>0.70+/-0.98 ((238)U)>0.069+/-0.087 ((224)Ra)>0.036+/-0.044 ((235)U)>0.014+/-0.021 ((228)Th)>0.012+/-0.005 ((212)Pb)>0.00035+/-0.00029 ((230)Th)>0.00022+/-0.00009 ((232)Th). It is obvious that (210)Po, (228)Ra, (210)Pb and (226)Ra are the most important dose contributors in the drinking water intake. As far as the seventeen brands of analysed drinking water were concerned, the committed effective doses were in the range of 2.81-38.5 microSvyr(-1), all well below the reference level of the committed effective dose (100 microSvyr(-1)) recommended by the WHO. These data throw some light on the scale of the radiological impact on the public from some naturally occurring radionuclides in drinking water, and can also serve as a comparison for the dose contribution from artificial radionuclides released to the environment as a result of human practices. Based on the radionuclide composition in the analysed waters, comment was made on the new screening level for gross alpha activity in guidelines for drinking-water quality recommended by the WHO, 2004. PMID:19635638

  6. Production of a microcapsule agent of chromate-reducing Lysinibacillus fusiformis ZC1 and its application in remediation of chromate-spiked soil.

    PubMed

    Huang, Jun; Li, Jingxin; Wang, Gejiao

    2016-01-01

    Lysinibacillus fusiformis ZC1 is an efficient Cr(VI)-reducing bacterium that can transform the toxic and soluble chromate [Cr(VI)] form to the less toxic and precipitated chromite form [Cr(III)]. As such, this strain might be applicable for bioremediation of Cr(VI) in soil by reducing its bioavailability. The study objective was to prepare a microcapsule agent of strain ZC1 for bioremediation of Cr(VI)-contaminated soil. Using a single-factor orthogonal array design, the optimal fermentation medium was obtained and consisted of 6 g/L corn flour, 12 g/L soybean flour, 8 g/L NH4Cl and 6 g/L CaCl2. After enlarged fermentation, the cell and spore densities were 5.9 × 10(9) and 1.7 × 10(8) cfu/mL, respectively. The fermentation products were collected and embedded with 1 % gum arabic and 1 % sorbitol as the microcapsule carriers and were subsequently spray-dried. Strain ZC1 exhibited viable cell counts of (3.6 ± 0.44) × 10(10) cfu/g dw after 50-day storage at room temperature. In simulated soil bioremediation experiments, 67 % of Cr(VI) was reduced in 5 days with the inoculation of this microcapsule agent, and the Cr(VI) concentration was below the soil Cr(VI) standard level. The results demonstrated that the microcapsule agent of strain ZC1 is efficient for bioremediation of Cr(VI)-contaminated soil. PMID:27218011

  7. Spikes in quantum trajectories

    NASA Astrophysics Data System (ADS)

    Tilloy, Antoine; Bauer, Michel; Bernard, Denis

    2015-11-01

    A quantum system subjected to a strong continuous monitoring undergoes quantum jumps. This very-well-known fact hides a neglected subtlety: sharp scale-invariant fluctuations invariably decorate the jump process, even in the limit where the measurement rate is very large. This article is devoted to the quantitative study of these remaining fluctuations, which we call spikes, and to a discussion of their physical status. We start by introducing a classical model where the origin of these fluctuations is more intuitive, and then jump to the quantum realm where their existence is less intuitive. We compute the exact distribution of the spikes for a continuously monitored qubit. We conclude by discussing their physical and operational relevance.

  8. Spike sorting of synchronous spikes from local neuron ensembles.

    PubMed

    Franke, Felix; Pröpper, Robert; Alle, Henrik; Meier, Philipp; Geiger, Jörg R P; Obermayer, Klaus; Munk, Matthias H J

    2015-10-01

    Synchronous spike discharge of cortical neurons is thought to be a fingerprint of neuronal cooperativity. Because neighboring neurons are more densely connected to one another than neurons that are located further apart, near-synchronous spike discharge can be expected to be prevalent and it might provide an important basis for cortical computations. Using microelectrodes to record local groups of neurons does not allow for the reliable separation of synchronous spikes from different cells, because available spike sorting algorithms cannot correctly resolve the temporally overlapping waveforms. We show that high spike sorting performance of in vivo recordings, including overlapping spikes, can be achieved with a recently developed filter-based template matching procedure. Using tetrodes with a three-dimensional structure, we demonstrate with simulated data and ground truth in vitro data, obtained by dual intracellular recording of two neurons located next to a tetrode, that the spike sorting of synchronous spikes can be as successful as the spike sorting of nonoverlapping spikes and that the spatial information provided by multielectrodes greatly reduces the error rates. We apply the method to tetrode recordings from the prefrontal cortex of behaving primates, and we show that overlapping spikes can be identified and assigned to individual neurons to study synchronous activity in local groups of neurons. PMID:26289473

  9. U and Th-series isotopes: a probe into time-dependent erosion processes in soils

    NASA Astrophysics Data System (ADS)

    Hillaire-Marcel, Claude; Ghaleb, Bassam; Barbecot, Florent

    2010-05-01

    Disequilibria between 238U-234Th-234U-230Th-226Ra-210Pb-210Po, 235U-231Pa and 232Th-228Ra-228Th, offer probes into time dependent processes over time scales ranging 106 a to a few days, thus the means to document soil erosion rates over a large array of time scales and hydroclimatic forcings. Because lithology constitutes a boundary condition, we intend to illustrate the behavior of such isotopes in carbonate-rich soils, with examples from cool-temperate (St Lawrence Lowlands, Canada) or arid settings (Palmyre area, Syria) but special attention to Mediterranean environments (SE France). In this later case, a >12 m thick unsaturated zone has been sampled, near Beziers, in the recharge zone of the "Astian carbonate sand Aquifer", firstly along a naturally exposed section, then in a cored sequence. Geochemical and mineralogical analyses, including stable isotopes were complemented by 228U, 234U, 230Th, 226Ra, 210Pb and 228Th, 232Th measurements from soil surface, down to about 12 m below surface. Whereas the upper 7 m depict geochemical and isotopic features linked to dissolution/re-precipitation processes with highly variable radioactive disequilibria, the lower part of the sequence shows distinctive properties. In this deep horizon, strong excesses in 234U and 230Th over parent isotopes (i.e. 238U and 234U, respectively) are observed simultaneously whereas 226Ra and 230Th are in secular equilibrium. We interpret these features as an indication for a slow-process enrichment in 234Th(234U) and 230Th, linked to dissolved U-decay during groundwater recharge events. 210Pb deficits (vs. parent 226Ra) are observed down to 12 m along the natural outcropping section and below the top-soil 210Pb-excess in the cored sequence, due to 222Rn-diffusion. It is concluded from this example that beside the strong impact on U- and Th-series disequilibria of fast chemical process occurring in the upper soil horizons, slower processes still leave an imprint with longer

  10. Spiking optical patterns and synchronization

    NASA Astrophysics Data System (ADS)

    Rosenbluh, Michael; Aviad, Yaara; Cohen, Elad; Khaykovich, Lev; Kinzel, Wolfgang; Kopelowitz, Evi; Yoskovits, Pinhas; Kanter, Ido

    2007-10-01

    We analyze the time resolved spike statistics of a solitary and two mutually interacting chaotic semiconductor lasers whose chaos is characterized by apparently random, short intensity spikes. Repulsion between two successive spikes is observed, resulting in a refractory period, which is largest at laser threshold. For time intervals between spikes greater than the refractory period, the distribution of the intervals follows a Poisson distribution. The spiking pattern is highly periodic over time windows corresponding to the optical length of the external cavity, with a slow change of the spiking pattern as time increases. When zero-lag synchronization between two lasers is established, the statistics of the nearly perfectly matched spikes are not altered. The similarity of these features to those found in complex interacting neural networks, suggests the use of laser systems as simpler physical models for neural networks.

  11. Radioxenon spiked air.

    PubMed

    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

  12. Radioxenon spiked air

    DOE PAGESBeta

    Watrous, Matthew G.; Delmore, James E.; Hague, Robert K.; Houghton, Tracy P.; Jenson, Douglas D.; Mann, Nick R.

    2015-08-27

    Four of the radioactive xenon isotopes (131mXe, 133mXe, 133Xe and 135Xe) 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 Internationalmore » 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 study 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.« less

  13. Rayleigh--Taylor spike evaporation

    SciTech Connect

    Schappert, G. T.; Batha, S. H.; Klare, K. A.; Hollowell, D. E.; Mason, R. J.

    2001-09-01

    Laser-based experiments have shown that Rayleigh--Taylor (RT) growth in thin, perturbed copper foils leads to a phase dominated by narrow spikes between thin bubbles. These experiments were well modeled and diagnosed until this '' spike'' phase, but not into this spike phase. Experiments were designed, modeled, and performed on the OMEGA laser [T. R. Boehly, D. L. Brown, R. S. Craxton , Opt. Commun. 133, 495 (1997)] to study the late-time spike phase. To simulate the conditions and evolution of late time RT, a copper target was fabricated consisting of a series of thin ridges (spikes in cross section) 150 {mu}m apart on a thin flat copper backing. The target was placed on the side of a scale-1.2 hohlraum with the ridges pointing into the hohlraum, which was heated to 190 eV. Side-on radiography imaged the evolution of the ridges and flat copper backing into the typical RT bubble and spike structure including the '' mushroom-like feet'' on the tips of the spikes. RAGE computer models [R. M. Baltrusaitis, M. L. Gittings, R. P. Weaver, R. F. Benjamin, and J. M. Budzinski, Phys. Fluids 8, 2471 (1996)] show the formation of the '' mushrooms,'' as well as how the backing material converges to lengthen the spike. The computer predictions of evolving spike and bubble lengths match measurements fairly well for the thicker backing targets but not for the thinner backings.

  14. Radioxenon spiked air

    SciTech Connect

    Watrous, Matthew G.; Delmore, James E.; Hague, Robert K.; Houghton, Tracy P.; Jenson, Douglas D.; Mann, Nick R.

    2015-08-27

    Four of the radioactive xenon isotopes (131mXe, 133mXe, 133Xe and 135Xe) 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 study 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.

  15. An online spike detection and spike classification algorithm capable of instantaneous resolution of overlapping spikes

    PubMed Central

    Natora, Michal; Boucsein, Clemens; Munk, Matthias H. J.; Obermayer, Klaus

    2009-01-01

    For the analysis of neuronal cooperativity, simultaneously recorded extracellular signals from neighboring neurons need to be sorted reliably by a spike sorting method. Many algorithms have been developed to this end, however, to date, none of them manages to fulfill a set of demanding requirements. In particular, it is desirable to have an algorithm that operates online, detects and classifies overlapping spikes in real time, and that adapts to non-stationary data. Here, we present a combined spike detection and classification algorithm, which explicitly addresses these issues. Our approach makes use of linear filters to find a new representation of the data and to optimally enhance the signal-to-noise ratio. We introduce a method called “Deconfusion” which de-correlates the filter outputs and provides source separation. Finally, a set of well-defined thresholds is applied and leads to simultaneous spike detection and spike classification. By incorporating a direct feedback, the algorithm adapts to non-stationary data and is, therefore, well suited for acute recordings. We evaluate our method on simulated and experimental data, including simultaneous intra/extra-cellular recordings made in slices of a rat cortex and recordings from the prefrontal cortex of awake behaving macaques. We compare the results to existing spike detection as well as spike sorting methods. We conclude that our algorithm meets all of the mentioned requirements and outperforms other methods under realistic signal-to-noise ratios and in the presence of overlapping spikes. PMID:19499318

  16. Mapping Spikes to Sensations

    PubMed Central

    Stüttgen, Maik C.; Schwarz, Cornelius; Jäkel, Frank

    2011-01-01

    Single-unit recordings conducted during perceptual decision-making tasks have yielded tremendous insights into the neural coding of sensory stimuli. In such experiments, detection or discrimination behavior (the psychometric data) is observed in parallel with spike trains in sensory neurons (the neurometric data). Frequently, candidate neural codes for information read-out are pitted against each other by transforming the neurometric data in some way and asking which code’s performance most closely approximates the psychometric performance. The code that matches the psychometric performance best is retained as a viable candidate and the others are rejected. In following this strategy, psychometric data is often considered to provide an unbiased measure of perceptual sensitivity. It is rarely acknowledged that psychometric data result from a complex interplay of sensory and non-sensory processes and that neglect of these processes may result in misestimating psychophysical sensitivity. This again may lead to erroneous conclusions regarding the adequacy of candidate neural codes. In this review, we first discuss requirements on the neural data for a subsequent neurometric-psychometric comparison. We then focus on different psychophysical tasks for the assessment of detection and discrimination performance and the cognitive processes that may underlie their execution. We discuss further factors that may compromise psychometric performance and how they can be detected or avoided. We believe that these considerations point to shortcomings in our understanding of the processes underlying perceptual decisions, and therefore offer potential for future research. PMID:22084627

  17. An investigation into the upward transport of uranium-series radionuclides in soils and uptake by plants.

    PubMed

    Pérez-Sánchez, D; Thorne, M C

    2014-09-01

    soil, but to assume that both (210)Pb and (210)Po can be treated as being present in secular equilibrium with the (226)Ra. This simplification is not always appropriate. Where geochemical conditions are such that the (226)Ra migrates upward in the soil column faster than (210)Pb and (210)Po, disequilibrium is not a significant issue, as the (226)Ra supports (210)Pb and (210)Po at concentrations somewhat below those estimated on the basis of assumed secular equilibrium. However, for low, but realistic, values of the distribution coefficients for (210)Pb and (210)Po and high, but realistic, distribution coefficients for (226)Ra, the (210)Pb and (210)Po can reach the surface soil in high concentrations that are not locally supported by (226)Ra. 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. PMID:24984104

  18. Wavelet analysis of epileptic spikes

    NASA Astrophysics Data System (ADS)

    Latka, Miroslaw; Was, Ziemowit; Kozik, Andrzej; West, Bruce J.

    2003-05-01

    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.

  19. Geophone with depth sensitive spikes

    SciTech Connect

    Rice, J.A.; Houston, L.M.; Arevalo, R.

    1992-06-23

    This patent describes a geophone. It comprises a seismic sensitive element for sensing elastic motion and converting the motion to an electrical signal, a housing for enclosing the seismic element, and an elongated spike attachable to the housing.

  20. Comparison of magnetoencephalographic spikes with and without concurrent electroencephalographic spikes in extratemporal epilepsy.

    PubMed

    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

  1. A 500 year sediment lake record of anthropogenic and natural inputs to Windermere (English Lake District) using double-spike lead isotopes, radiochronology, and sediment microanalysis.

    PubMed

    Miller, Helen; Croudace, Ian W; Bull, Jonathan M; Cotterill, Carol J; Dix, Justin K; Taylor, Rex N

    2014-07-01

    A high-resolution record of pollution is preserved in recent sediments from Windermere, the largest lake in the English Lake District. Data derived from X-ray core scanning (validated against wavelength dispersive X-ray fluorescence), radiochronological techniques ((210)Pb and (137)Cs) and ultrahigh precision, double-spike mass spectrometry for lead isotopes are combined to decipher the anthropogenic inputs to the lake. The sediment record suggests that while most element concentrations have been stable, there has been a significant increase in lead, zinc, and copper concentrations since the 1930s. Lead isotope down-core variations identify three major contributory sources of anthropogenic (industrial) lead, comprising gasoline lead, coal combustion lead (most likely source is coal-fired steam ships), and lead derived from Carboniferous Pb-Zn mineralization (mining activities). Periods of metal workings do not correlate with peaks in heavy metals due to the trapping efficiency of up-system lakes in the catchment. Heavy metal increases could be due to flood-induced metal inwash after the cessation of mining and the weathering of bedrock in the catchment. The combination of sediment analysis techniques used provides new insights into the pollutant depositional history of Windermere and could be similarly applied to other lake systems to determine the timing and scale of anthropogenic inputs. PMID:24902065

  2. Geochemistry and Chemical Weathering in Soils along an Earthworm Invasion Gradient

    NASA Astrophysics Data System (ADS)

    Resner, K.; Yoo, K.; Aufdenkampe, A. K.; Hale, C.; Sebestyen, S. D.

    2010-12-01

    One of the central tenets in geomorphology is that a chemical denudation rate is limited by the total denudation rate, which controls how fast minerals are exposed to reactive environments of the earth’s surface. Though the mineral supply rate has been routinely tied to tectonic uplifts, in soil mantled landscapes, organisms such as earthworms may also significantly contribute to exposing minerals to varying geochemical environments and thus altering chemical denudation rates of the landscapes they inhabit through mineral translocation. In glaciated parts of North America, many forests evolved without native earthworms, since the last glacial retreat, until they were invaded by exotic earthworm species that arrived with agriculture, recreational fishing, and logging. Therefore, an earthworm invasion chronosequence in northern Minnesota--the focus of this ongoing study--provides an ideal natural laboratory to quantitatively study how burrowing organisms, by mixing soils, contribute to chemically denuding the landscapes. We are currently determining the inorganic chemistry of soils along a ~200 meter long transect that includes pre earthworm invasion soils as well as soils populated with several earthworm species with different burrowing habits. Additionally, six soils pits along the transect are densely installed with lysimeters, piezometers, and gas sampling tubes. The soils’ elemental chemistry profiles show that earthworms have significantly relocated minerals vertically, which is consistent with the 210Pb activity profiles determined with gamma spectroscopy. Major elements, depending on their solubility, biological demands, and susceptibility to be complexed with organic matter, respond to the enhanced mixing rates in different ways. To constrain the impacts of earthworm burrowing on chemical denudation, we are also measuring cations, anions, and alkalinity in the water samples collected with the lysimeters and piezometers. Ultimately, the soil and water

  3. Learning Universal Computations with Spikes

    PubMed Central

    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

  4. Leach tests on grouts made with actual and trace metal-spiked synthetic phosphate/sulfate waste

    SciTech Connect

    Serne, R.J.; Martin, W.J.; LeGore, V.L.; Lindenmeier, C.W.; McLaurine, S.B.; Martin, P.F.C.; Lokken, R.O.

    1989-10-01

    Pacific Northwest Laboratory conducted experiments to produce empirical leach rate data for phosphate-sulfate waste (PSW) grout. Effective diffusivities were measured for various radionuclides ({sup 90}Sr, {sup 99}Tc, {sup 14}C, {sup 129}I, {sup 137}Cs, {sup 60}Co, {sup 54}Mn, and U), stable major components (NO{sub 3}{sup {minus}}, SO{sub 4}{sup 2{minus}}, H{sub 3}BO{sub 3}, 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 {sup 137}Cs, {sup 60}Co, {sup 54}Mn, {sup 109}Cd, {sup 51}Cr, {sup 210}Pb, {sup 203}Hg, or As. For those trace species with detectable leach rates, {sup 125}I appeared to have the greatest leach rate, followed by {sup 99}Tc, {sup 75}Se, and finally U, {sup 14}C, and {sup 110m}Ag. 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.

  5. Distribution of radionuclides in surface soils, Singhbhum Shear Zone, India and associated dose.

    PubMed

    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

  6. Automatic Spike Sorting Using Tuning Information

    PubMed Central

    Ventura, Valérie

    2011-01-01

    Current spike sorting methods focus on clustering neurons’ characteristic spike waveforms. The resulting spike-sorted data are typically used to estimate how covariates of interest modulate the firing rates of neurons. However, when these covariates do modulate the firing rates, they provide information about spikes’ identities, which thus far have been ignored for the purpose of spike sorting. This letter describes a novel approach to spike sorting, which incorporates both waveform information and tuning information obtained from the modulation of firing rates. Because it efficiently uses all the available information, this spike sorter yields lower spike misclassification rates than traditional automatic spike sorters. This theoretical result is verified empirically on several examples. The proposed method does not require additional assumptions; only its implementation is different. It essentially consists of performing spike sorting and tuning estimation simultaneously rather than sequentially, as is currently done. We used an expectation-maximization maximum likelihood algorithm to implement the new spike sorter. We present the general form of this algorithm and provide a detailed implementable version under the assumptions that neurons are independent and spike according to Poisson processes. Finally, we uncover a systematic flaw of spike sorting based on waveform information only. PMID:19548802

  7. Prospective Coding by Spiking Neurons

    PubMed Central

    Brea, Johanni; Gaál, Alexisz Tamás; Senn, Walter

    2016-01-01

    Animals learn to make predictions, such as associating the sound of a bell with upcoming feeding or predicting a movement that a motor command is eliciting. How predictions are realized on the neuronal level and what plasticity rule underlies their learning is not well understood. Here we propose a biologically plausible synaptic plasticity rule to learn predictions on a single neuron level on a timescale of seconds. The learning rule allows a spiking two-compartment neuron to match its current firing rate to its own expected future discounted firing rate. For instance, if an originally neutral event is repeatedly followed by an event that elevates the firing rate of a neuron, the originally neutral event will eventually also elevate the neuron’s firing rate. The plasticity rule is a form of spike timing dependent plasticity in which a presynaptic spike followed by a postsynaptic spike leads to potentiation. Even if the plasticity window has a width of 20 milliseconds, associations on the time scale of seconds can be learned. We illustrate prospective coding with three examples: learning to predict a time varying input, learning to predict the next stimulus in a delayed paired-associate task and learning with a recurrent network to reproduce a temporally compressed version of a sequence. We discuss the potential role of the learning mechanism in classical trace conditioning. In the special case that the signal to be predicted encodes reward, the neuron learns to predict the discounted future reward and learning is closely related to the temporal difference learning algorithm TD(λ). PMID:27341100

  8. Measuring multiple spike train synchrony.

    PubMed

    Kreuz, Thomas; Chicharro, Daniel; Andrzejak, Ralph G; Haas, Julie S; Abarbanel, Henry D I

    2009-10-15

    Measures of multiple spike train synchrony are essential in order to study issues such as spike timing reliability, network synchronization, and neuronal coding. These measures can broadly be divided in multivariate measures and averages over bivariate measures. One of the most recent bivariate approaches, the ISI-distance, employs the ratio of instantaneous interspike intervals (ISIs). In this study we propose two extensions of the ISI-distance, the straightforward averaged bivariate ISI-distance and the multivariate ISI-diversity based on the coefficient of variation. Like the original measure these extensions combine many properties desirable in applications to real data. In particular, they are parameter-free, time scale independent, and easy to visualize in a time-resolved manner, as we illustrate with in vitro recordings from a cortical neuron. Using a simulated network of Hindemarsh-Rose neurons as a controlled configuration we compare the performance of our methods in distinguishing different levels of multi-neuron spike train synchrony to the performance of six other previously published measures. We show and explain why the averaged bivariate measures perform better than the multivariate ones and why the multivariate ISI-diversity is the best performer among the multivariate methods. Finally, in a comparison against standard methods that rely on moving window estimates, we use single-unit monkey data to demonstrate the advantages of the instantaneous nature of our methods. PMID:19591867

  9. iSpike: a spiking neural interface for the iCub robot.

    PubMed

    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.

    PubMed

    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. Threshold increases in soil lead and mercury from tropospheric deposition across an elevational gradient.

    PubMed

    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

  12. Multiscale analysis of neural spike trains.

    PubMed

    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

  13. Assessment of soil erosion and deposition rates in a Moroccan agricultural field using fallout 137Cs and 210Pbex.

    PubMed

    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

  14. Forms and accumulation of soil P in natural and recently restored peatlands - Upper Klamath Lake, Oregon, USA

    USGS Publications Warehouse

    Graham, S.A.; Craft, C.B.; McCormick, P.V.; Aldous, A.

    2005-01-01

    Forms, amounts, and accumulation of soil phosphorus (P) were measured in natural and recently restored marshes surrounding Upper Klamath Lake located in south-central Oregon, USA to determine rates of P accumulation in natural marshes and to assess changes in P pools caused by long-term drainage in recently restored marshes. Soil cores were collected from three natural marshes and radiometrically dated to determine recent (l37Cs-based) and long-term (210Pb-based) rates of peat accretion and P accumulation. A second set of soil cores collected from the three natural marshes and from three recently restored marshes was analyzed using a modification of the Hedley procedure to determine the forms and amounts of soil P. Total P in the recently restored marshes (222 to 311 ??g cm-3) was 2-3 times greater than in the natural marshes (103 to 117 ??g cm-3), primarily due to greater bulk density caused by soil subsidence, a consequence of long-term marsh drainage. Occluded Fe- and Al-bound Pi, calcium-bound Pi and residual P were 4 times, 22 times, and 5 times greater, respectively, in the recently restored marshes. More than 67% of the P pool in both the natural and recently restored marshes was present in recalcitrant forms (humic-acid P o and residual P) that provide long-term P storage in peat. Phosphorus accumulation in the natural marshes averaged 0.45 g m-2 yr-1 (137Cs) and 0.40 g m-2 yr-1 (210Pb), providing a benchmark for optimizing P sequestration in the recently restored marshes. Effective P sequestration in the recently restored marshes, however, will depend on re-establishing equilibrium between the P-enriched soils and the P concentration of floodwaters and a hydrologie regime similar to the natural marshes. ?? 2005, The Society of Wetland Scientists.

  15. Learning Precise Spike Train-to-Spike Train Transformations in Multilayer Feedforward Neuronal Networks.

    PubMed

    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

  16. Spike Decomposition Technique: Modeling and Performance Tests

    NASA Astrophysics Data System (ADS)

    Nita, Gelu M.; Fleishman, Gregory D.; Gary, Dale E.

    2008-12-01

    We develop an automated technique for fitting the spectral components of solar microwave spike bursts, which are characterized by narrowband spectral features. The algorithm is especially useful for periods when the spikes occur in densely packed clusters, where the algorithm is capable of decomposing overlapping spike structures into individual spectral components. To test the performance and applicability limits of this data reduction tool, we perform comprehensive modeling of spike clusters characterized by various typical bandwidths, spike densities, and amplitude distributions. We find that, for a wide range of favorable combinations of input parameters, the algorithm is able to recover the characteristic features of the modeled distributions within reasonable confidence intervals. Having model-tested the algorithm against spike overlap, broadband spectral background, noise contamination, and possible malfunction of some spectral channels, we apply the technique to a spike cluster recorded by the Chinese Purple Mountain Observatory (PMO) spectrometer, operating above 4.5 GHz. We study the variation of the spike distribution parameters, such as amplitude, bandwidth, and related derived physical parameters, as a function of time. The method can be further applied to observations from other instruments and to other types of fine structures.

  17. A "Last Word" on Ice Spikes.

    ERIC Educational Resources Information Center

    Perry, Helene F.

    1995-01-01

    Attempts an explanation of how "ice spikes" are formed. The spikes are upward protrusions of ice that occur when water expands as it cools in a rigid container of low thermal conductivity. Describes the results of an investigation and includes color photos. (LZ)

  18. Spiking dynamics of interacting oscillatory neurons

    NASA Astrophysics Data System (ADS)

    Kazantsev, V. B.; Nekorkin, V. I.; Binczak, S.; Jacquir, S.; Bilbault, J. M.

    2005-06-01

    Spiking sequences emerging from dynamical interaction in a pair of oscillatory neurons are investigated theoretically and experimentally. The model comprises two unidirectionally coupled FitzHugh-Nagumo units with modified excitability (MFHN). The first (master) unit exhibits a periodic spike sequence with a certain frequency. The second (slave) unit is in its excitable mode and responds on the input signal with a complex (chaotic) spike trains. We analyze the dynamic mechanisms underlying different response behavior depending on interaction strength. Spiking phase maps describing the response dynamics are obtained. Complex phase locking and chaotic sequences are investigated. We show how the response spike trains can be effectively controlled by the interaction parameter and discuss the problem of neuronal information encoding.

  19. Stochastic variational learning in recurrent spiking networks

    PubMed Central

    Jimenez Rezende, Danilo; Gerstner, Wulfram

    2014-01-01

    The ability to learn and perform statistical inference with biologically plausible recurrent networks of spiking neurons is an important step toward 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 both stationary 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. PMID:24772078

  20. Millisecond Radio Spikes in the Decimetric Band

    NASA Astrophysics Data System (ADS)

    dąbrowski, B. P.; Rudawy, P.; Karlický, M.

    2011-11-01

    We present the results of the analysis of thirteen events consisting of dm-spikes observed in Toruń between 15 March 2000 and 30 October 2001. The events were obtained with a very high time resolution (80 microseconds) radio spectrograph in the 1352 - 1490 MHz range. These data were complemented with observations from the radio spectrograph at Ondřejov in the 0.8 - 2.0 GHz band. We evaluated the basic characteristics of the individual spikes (duration, spectral width, and frequency drifts), as well as their groups and chains, the location of their emission sources, and the temporal correlations of the emissions with various phases of the associated solar flares. We found that the mean duration and spectral width of the radio spikes are equal to 0.036 s and 9.96 MHz, respectively. Distributions of the duration and spectral widths of the spikes have positive skewness for all investigated events. Each spike shows positive or negative frequency drift. The mean negative and positive drifts of the investigated spikes are equal to -776 MHz s-1 and 1608 MHz s-1, respectively. The emission sources of the dm-spikes are located mainly at disk center. We have noticed two kinds of chains, with and without frequency drifts. The mean durations of the chains vary between 0.067 s and 0.509 s, while their spectral widths vary between 7.2 MHz and 17.25 MHz. The mean duration of an individual spike observed in a chain was equal to 0.03 s. While we found some agreement between the global characteristics of the groups of spikes recorded with the two instruments located in Toruń and Ondřejov, we did not find any one-to-one relation between individual spikes.

  1. Millisecond Radio Spikes in the Decimetric Band

    NASA Astrophysics Data System (ADS)

    Dąbrowski, B. P.; Rudawy, P.; Karlický, M.

    We present the results of the analysis of thirteen events consisting of dm-spikes observed in Toruń between 15 March 2000 and 30 October 2001. The events were obtained with a very high time resolution (80 microseconds) radio spectrograph in the 1352 - 1490 MHz range. These data were complemented with observations from the radio spectrograph at Ondřejov in the 0.8 - 2.0 GHz band. We evaluated the basic characteristics of the individual spikes (duration, spectral width, and frequency drifts), as well as their groups and chains, the location of their emission sources, and the temporal correlations of the emissions with various phases of the associated solar flares. We found that the mean duration and spectral width of the radio spikes are equal to 0.036 s and 9.96 MHz, respectively. Distributions of the duration and spectral widths of the spikes have positive skewness for all investigated events. Each spike shows positive or negative frequency drift. The mean negative and positive drifts of the investigated spikes are equal to -776 MHz s-1 and 1608 MHz s-1, respectively. The emission sources of the dm-spikes are located mainly at disk center. We have noticed two kinds of chains, with and without frequency drifts. The mean durations of the chains vary between 0.067 s and 0.509 s, while their spectral widths vary between 7.2 MHz and 17.25 MHz. The mean duration of an individual spike observed in a chain was equal to 0.03 s. While we found some agreement between the global characteristics of the groups of spikes recorded with the two instruments located in Toruń and Ondřejov, we did not find any one-to-one relation between individual spikes.

  2. The Global Spike: Conserved Dendritic Properties Enable Unique Ca2+ Spike Generation in Low-Threshold Spiking Neurons

    PubMed Central

    Connelly, William M.; Crunelli, Vincenzo

    2015-01-01

    Low-threshold Ca2+ spikes (LTS) are an indispensible signaling mechanism for neurons in areas including the cortex, cerebellum, basal ganglia, and thalamus. They have critical physiological roles and have been strongly associated with disorders including epilepsy, Parkinson's disease, and schizophrenia. However, although dendritic T-type Ca2+ channels have been implicated in LTS generation, because the properties of low-threshold spiking neuron dendrites are unknown, the precise mechanism has remained elusive. Here, combining data from fluorescence-targeted dendritic recordings and Ca2+ imaging from low-threshold spiking cells in rat brain slices with computational modeling, the cellular mechanism responsible for LTS generation is established. Our data demonstrate that key somatodendritic electrical conduction properties are highly conserved between glutamatergic thalamocortical neurons and GABAergic thalamic reticular nucleus neurons and that these properties are critical for LTS generation. In particular, the efficiency of soma to dendrite voltage transfer is highly asymmetric in low-threshold spiking cells, and in the somatofugal direction, these neurons are particularly electrotonically compact. Our data demonstrate that LTS have remarkably similar amplitudes and occur synchronously throughout the dendritic tree. In fact, these Ca2+ spikes cannot occur locally in any part of the cell, and hence we reveal that LTS are generated by a unique whole-cell mechanism that means they always occur as spatially global spikes. This all-or-none, global electrical and biochemical signaling mechanism clearly distinguishes LTS from other signals, including backpropagating action potentials and dendritic Ca2+/NMDA spikes, and has important consequences for dendritic function in low-threshold spiking neurons. SIGNIFICANCE STATEMENT Low-threshold Ca2+ spikes (LTS) are critical for important physiological processes, including generation of sleep-related oscillations, and are

  3. Cluster-based spike detection algorithm adapts to interpatient and intrapatient variation in spike morphology.

    PubMed

    Nonclercq, Antoine; Foulon, Martine; Verheulpen, Denis; De Cock, Cathy; Buzatu, Marga; Mathys, Pierre; Van Bogaert, Patrick

    2012-09-30

    Visual quantification of interictal epileptiform activity is time consuming and requires a high level of expert's vigilance. This is especially true for overnight recordings of patient suffering from epileptic encephalopathy with continuous spike and waves during slow-wave sleep (CSWS) as they can show tens of thousands of spikes. Automatic spike detection would be attractive for this condition, but available algorithms have methodological limitations related to variation in spike morphology both between patients and within a single recording. We propose a fully automated method of interictal spike detection that adapts to interpatient and intrapatient variation in spike morphology. The algorithm works in five steps. (1) Spikes are detected using parameters suitable for highly sensitive detection. (2) Detected spikes are separated into clusters. (3) The number of clusters is automatically adjusted. (4) Centroids are used as templates for more specific spike detections, therefore adapting to the types of spike morphology. (5) Detected spikes are summed. The algorithm was evaluated on EEG samples from 20 children suffering from epilepsy with CSWS. When compared to the manual scoring of 3 EEG experts (3 records), the algorithm demonstrated similar performance since sensitivity and selectivity were 0.3% higher and 0.4% lower, respectively. The algorithm showed little difference compared to the manual scoring of another expert for the spike-and-wave index evaluation in 17 additional records (the mean absolute difference was 3.8%). This algorithm is therefore efficient for the count of interictal spikes and determination of a spike-and-wave index. PMID:22850558

  4. Spike Decomposition Technique: Modeling and Performance Tests

    NASA Astrophysics Data System (ADS)

    Nita, G. M.; Fleishman, G. D.; Gary, D. E.

    2008-05-01

    We develop an automated technique for fitting the spectral components of solar microwave spike bursts characterized by narrow-band (1-50~MHz) features of 1-10~ms duration, which are thought to be due to Electron-Cyclotron Maser emission. The algorithm is especially useful for periods when the spikes occur in densely packed clusters, where the algorithm is capable of decomposing overlapping spike structures into individual spectral components. To test the performance and applicability limits of this forward fitting algorithm, we perform comprehensive modeling of spike clusters characterized by various typical bandwidths, spike densities, and amplitude distributions. We find that, for a wide range of input parameters, the algorithm is able to recover the characteristic features of the modeled distributions within reasonable confidence intervals. Having model-tested the algorithm comprehensively against spike overlap, broadband spectral background, noise contamination, and possible contamination of cross-channel polarization, we apply the technique to observational data obtained from different instruments in different frequency ranges. Specifically, we studied spike clusters recorded by a Chinese Purple Mountain Observatory (PMO) spectrometer above 4.5 GHz and by Owens Valley Solar Array's FASR Subsystem Testbed instrument above 1 GHz. We study variation of the spike distribution parameters, such as amplitude, bandwidth and related derived physical parameters as a function of frequency and time. We discuss the implications of our results for the choice between competing models of spike generation and underlying physical processes. The method can be further applied to observations from other instruments and to other types of radio spectral fine structures. This work was supported in part by NSF grants AST-0607544 and ATM-0707319 and NASA grant NNG06GJ40G to New Jersey Institute of Technology.

  5. Soil Chemical Weathering and Nutrient Budgets along an Earthworm Invasion Chronosequence in a Northern Minnesota Forest

    NASA Astrophysics Data System (ADS)

    Resner, K. E.; Yoo, K.; Sebestyen, S. D.; Aufdenkampe, A. K.; Lyttle, A.; Weinman, B. A.; Blum, A.; Hale, C. M.

    2011-12-01

    We are investigating the impact of exotic earthworms on the rate of nutrient and ion release from soil chemical weathering along an ~200 m invasion chronosequence in a northern Minnesota sugar maple forest. The earthworms belong to three ecological groups that represent different feeding and burrowing behaviors, all of which were introduced from Europe to the previously earthworm-free Great Lakes Region through fishing and agricultural activities. As earthworms digest and mix the soil, we hypothesize that they significantly alter chemical weathering processes by incorporating mineral surfaces to new geochemical environments in their intestines and at different soil depths. The effect of mixing on soil morphology is dramatic, but biogeochemical changes remain largely unknown and therefore are poorly coupled to the current and potential changes in forest ecosystems under the threat of exotic earthworms. We analyze the activities of short-lived isotopes 137-Cs and 210-Pb along with the inorganic chemistry of soil, water, and leaf litter across an invasion transect and link these measurements to the biomass and species composition of exotic earthworms. Earthworms vertically relocate minerals and organic matter largely within the top ~10 cm, which is reflected in the depth profiles of the short-lived isotopes. Among the inorganic nutrients analyzed, Ca is of particular interest due to sugar maple's aptitude for recycling Ca. Fractional mass loss values (tau) of Ca, relative to the soil's parent material, show an enrichment factor of 14 in the least invaded A horizon soils. However, such a high enrichment factor declines dramatically in the heavily invaded soils, suggesting that earthworm activities contribute to leaching Ca. In contrast, the enrichment factor of Fe increases with greater degrees of earthworm invasion, which is consistent with the extraction chemistry data showing greater quantities of pedogenic crystalline iron oxides and greater mineral specific

  6. Decoding of intracellular calcium spike trains

    NASA Astrophysics Data System (ADS)

    Prank, K.; Läer, L.; von zur Mühlen, A.; Brabant, G.; Schöfl, C.

    1998-04-01

    Cells respond to external signals, such as hormonal stimuli, by generating repetitive spikes in the intracellular free-calcium concentration ([Ca2+]i). These [Ca2+]i spikes, which can be modulated in their frequency and amplitude, regulate diverse cellular processes. Experimentally, [Ca2+]i can be assessed continuously in contrast to cellular responses represented by the activation of proteins. We propose a mathematical model that allows for the on-line decoding of [Ca2+]i spike trains into cellular responses represented by the activation of proteins.

  7. Spike detection using the continuous wavelet transform.

    PubMed

    Nenadic, Zoran; Burdick, Joel W

    2005-01-01

    This paper combines wavelet transforms with basic detection theory to develop a new unsupervised method for robustly detecting and localizing spikes in noisy neural recordings. The method does not require the construction of templates, or the supervised setting of thresholds. We present extensive Monte Carlo simulations, based on actual extracellular recordings, to show that this technique surpasses other commonly used methods in a wide variety of recording conditions. We further demonstrate that falsely detected spikes corresponding to our method resemble actual spikes more than the false positives of other techniques such as amplitude thresholding. Moreover, the simplicity of the method allows for nearly real-time execution. PMID:15651566

  8. Spiking sediment with organochlorines for toxicity testing

    SciTech Connect

    Murdoch, M.H.; Chapman, P.M.; Norman, D.M.; Quintino, V.M.

    1997-07-01

    Sediment toxicity testing integrates responses to sediment variables and hence does not directly indicate cause and effect. One tool for determining cause and effect is sediment spiking, in which relatively uncontaminated sediment is amended with known amounts of contaminants, then tested for toxicity. However, sediment spiking methods vary considerably. The present study details appropriate methodologies (dry and wet spiking) for amending sediments with a range of organic contaminant concentrations, i.e., polychlorinated biphenyl (PCB). Target and actual concentrations were similar. A dose-response was determined, but PCB was not toxic in an acute sediment toxicity test. Chronic testing of these same sediments is reported in a companion article in this issue.

  9. Vibration (?) spikes during natural rain events

    NASA Technical Reports Server (NTRS)

    Short, David A.

    1994-01-01

    Limited analysis of optical rain gauge (ORG) data from shipboard and ground based sensors has shown the existence of spikes, possibly attributable to sensor vibration, while rain is occurring. An extreme example of this behavior was noted aboard the PRC#5 on the evening of December 24, 1992 as the ship began repositioning during a rain event in the TOGA/COARE IFA. The spikes are readily evident in the one-second resolution data, but may be indistinguishable from natural rain rate fluctuations in subsampled or averaged data. Such spikes result in increased rainfall totals.

  10. Lixiviation of natural radionuclides and heavy metals in tropical soils amended with phosphogypsum.

    PubMed

    Nisti, M B; Saueia, C R; Malheiro, L H; Groppo, G H; Mazzilli, B P

    2015-06-01

    The main phosphate industries in Brazil are responsible for the annual production of 5.5 million tons of a residue (phosphogypsum), which is stored in stacks. The presence of radionuclides and metals puts restrictions on the use of phosphogypsum in agriculture. To assure a safe utilization, it is important to estimate the lixiviation of the radionuclides ((238)U, (226)Ra, (210)Pb, (210)Po, (232)Th and (228)Ra) and metals (As, Cd, Cr, Ni, Se, Hg and Pb) present in phosphogypsum. For this purpose, an experiment was carried out, in which columns filled with sandy and clay Brazilian typical soils mixed with phosphogypsum were percolated with water, to achieve a mild extraction of these elements. The results obtained for the concentration of the radionuclides and metals in the leachate were low; giving evidence that, even when these elements are present in the phosphogypsum, they do not contribute to an enhancement of their content in water. PMID:25841114