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Sample records for 206pb 207pb 208pb

  1. Direct determination of lead isotopes (206Pb, 207Pb, 208Pb) in arctic ice samples at picogram per gram levels using inductively coupled plasma-sector field MS coupled with a high-efficiency sample introduction system.

    PubMed

    Krachler, Michael; Zheng, James; Fisher, David; Shotyk, William

    2004-09-15

    Adopting strict cleanroom procedures, ice samples from the Canadian High Arctic have been analyzed for Pb concentrations and Pb isotopes (206Pb, 207Pb, 208Pb) using ICP-SMS. The detection limit for Pb (0.06 pg g(-1)) was approximately 2 orders of magnitude lower than the lowest concentration of Pb in the ice samples (range, 4.3-1660 pg g(-1); median, 45 pg g(-1)). Acidification of ice samples with high-purity HNO3 for stabilization purposes contributed only 0.004 pg of Pb g(-1), which is an insignificant source of Pb. Using a new sample introduction system consisting of a heated (140 degrees C) minicyclonic spray chamber and a Peltier cooled condenser (2 degrees C) and by replacing the conventional sample cone with a high-performance cone, signal intensities for Pb were increased by approximately 1 order of magnitude. Thus, it was possible not only to measure Pb isotope ratios directly using ICP-SMS but also to achieve reasonable precision (approximately 0.2%) at low picogram per gram concentrations of total Pb. This precision is comparable to that achievable by thermal ionization mass spectrometry at such low Pb concentrations, but the ICP-SMS requires much less sample volume (approximately 2 mL), needs no sample pretreatment, and therefore is considerably faster and less expensive than the conventional approach. Even though absolute Pb concentrations in two ice samples dating from 1974 and 1852 were very similar (9 and 6 pg g(-1)) their fundamentally different isotopic signature (206Pb/207Pb: 1.169 +/- 0.002 vs 1.147 +/- 0.003) clearly indicates different sources of Pb. The analytical procedures described here, therefore, offer great promise for fingerprinting the predominant sources of atmospheric Pb in polar snow and ice.

  2. 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

    The surfaces of Sphagnum carpets were marked with plastic mesh and 1 year later the production of plant matter was harvested in four ombrotrophic bogs from two regions of southern Germany: Upper Bavaria (Oberbayern, OB) and the Northern Black Forest (Nordschwarzwald, NBF). Radioactive, 210Pb was determined in solid samples using ultralow background gamma spectrometry while total Pb concentrations and stable isotopes (206Pb, 207Pb, 208Pb) were determined in acid digests using ICP-SMS. Up to 12 samples (40 × 40 cm) were collected per site, and 6-10 sites investigated per bog. The greatest variations within a given sampling site were in the range 212-532 Bq kg-1 for 210Pb activity, whereas 206Pb/207Pb and 208Pb/206Pb varied less than 1%. The median values of all parameters for the sites (6-10 per bog) were not significantly different. The median activities of 210Pb (Bq kg-1) in the mosses collected from the bogs in NBF (HO = 372 ± 56, n = 55; WI = 342 ± 58, n = 93) were slightly less from those in OB (GS = 394 ± 50, n = 55; KL = 425 ± 58, n = 24). However, the mosses in the NBF bogs exhibited much greater productivity (187-202 g m-2 a-1) compared to those of OB (71-91 g m-2 a-1), and this has a profound impact on the accumulation rates of 210Pb (Bq m-2 a-1), with the bogs in the NBF yielding fluxes (HO = 73 ± 30; WI = 65 ± 20) which are twice those of OB (GS = 29 ± 11; KL = 40 ± 13). Using the air concentrations of 210Pb measured at Schauinsland (SIL) in the southern Black Forest and average annual precipitation, the atmospheric fluxes of 210Pb at SIL (340 Bq m-2 a-1) exceeds the corresponding values obtained from the mosses by a factor of five, providing the first quantitative estimate of the net retention efficiency of 210Pb by Sphagnum. When the 210Pb activities of all moss samples are combined (n = 227), a significant decrease with increasing plant production rate is observed; in contrast, total Pb concentrations show the opposite trend. The contrasting

  3. New high spin states and isomers in the {sup 208}Pb and {sup 207}Pb nuclei

    SciTech Connect

    Broda, R.; Wrzesinski, J.; Pawlat, T.

    1996-12-31

    The two most prominent examples of the heavy doubly closed shell (DCS) nuclei, {sup 208}Pb and {sup 132}Sn, are not accessible by conventional heavy-ion fusion processes populating high-spin states. This experimental difficulty obscured for a long time the investigation of yrast high-spin states in both DCS and neighboring nuclei and consequently restricted the study of the shell model in its most attractive regions. Recent technical development of multidetector gamma arrays opened new ways to exploit more complex nuclear processes which populate the nuclei of interest with suitable yields for gamma spectroscopy and involve population of moderately high spin states. This new possibility extended the range of accessible spin values and is a promising way to reach new yrast states. Some of these states are expected to be of high configurational purity and can be a source of important shell model parameters which possibly can be used later to check the validity of the spherical shell model description at yet higher spin and higher excitation energy. The nuclei in the closest vicinity of {sup 132}Sn are produced in spontaneous fission and states with spin values up to I=14 can be reached in fission gamma spectroscopy studies with the presently achieved sensitivity of gamma arrays. New results on yrast states in the {sup 134}Te and {sup 135}I nuclei populated in fission of the {sup 248}Cm presented at this conference illustrate such application of the resolving power offered by modern gamma techniques.

  4. 26Al- 26Mg and 207Pb- 206Pb systematics of Allende CAIs: Canonical solar initial 26Al/ 27Al ratio reinstated

    NASA Astrophysics Data System (ADS)

    Jacobsen, Benjamin; Yin, Qing-zhu; Moynier, Frederic; Amelin, Yuri; Krot, Alexander N.; Nagashima, Kazuhide; Hutcheon, Ian D.; Palme, Herbert

    2008-07-01

    The precise knowledge of the initial 26Al/ 27Al ratio [( 26Al/ 27Al) 0] is crucial if we are to use the very first solid objects formed in our Solar System, calcium-aluminum-rich inclusions (CAIs) as the "time zero" age-anchor and guide future work with other short-lived radio-chronometers in the early Solar System, as well as determining the inventory of heat budgets from radioactivities for early planetary differentiation. New high-precision multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) measurements of 27Al/ 24Mg ratios and Mg-isotopic compositions of nine whole-rock CAIs (six mineralogically characterized fragments and three micro-drilled inclusions) from the CV carbonaceous chondrite, Allende yield a well-defined 26Al- 26Mg fossil isochron with an ( 26Al/ 27Al) 0 of (5.23 ± 0.13) × 10 - 5 . Internal mineral isochrons obtained for three of these CAIs ( A44A, AJEF, and A43) are consistent with the whole-rock CAI isochron. The mineral isochron of AJEF with ( 26Al/ 27Al) 0 = (4.96 ± 0.25) × 10 - 5 , anchored to our precisely determined absolute 207Pb- 206Pb age of 4567.60 ± 0.36 Ma for the same mineral separates, reinstate the "canonical" ( 26Al/ 27Al) 0 of 5 × 10 - 5 for the early Solar System. The uncertainty in ( 26Al/ 27Al) 0 corresponds to a maximum time span of ± 20 Ka (thousand years), suggesting that the Allende CAI formation events were culminated within this time span. Although all Allende CAIs studied experienced multistage formation history, including melting and evaporation in the solar nebula and post-crystallization alteration likely on the asteroidal parent body, the 26Al- 26Mg and U-Pb-isotopic systematics of the mineral separates and bulk CAIs behaved largely as closed-system since their formation. Our data do not support the "supra-canonical" 26Al/ 27Al ratio of individual minerals or their mixtures in CV CAIs, suggesting that the supra-canonical 26Al/ 27Al ratio in the CV CAIs may have resulted from post

  5. Lead fluxes and 206Pb/207Pb isotope ratios in rime and snow collected at remote mountain-top locations (Czech Republic, Central Europe): Patterns and sources

    NASA Astrophysics Data System (ADS)

    Cimova, Nikoleta; Novak, Martin; Chrastny, Vladislav; Curik, Jan; Veselovsky, Frantisek; Blaha, Vladimir; Prechova, Eva; Pasava, Jan; Houskova, Marie; Bohdalkova, Leona; Stepanova, Marketa; Mikova, Jitka; Krachler, Michael; Komarek, Arnost

    2016-10-01

    During three winter seasons (2009-2011), Pb concentrations were measured in precipitation at 10 high-elevation sites in the Czech Republic, close to the borders with Austria, Germany, Poland, and Slovakia. Soluble and insoluble Pb forms were quantified in snow (vertical deposition), and rime (horizontal deposition). The objective was to compare Pb input fluxes into ecosystems via vertical and horizontal deposition, and to identify the residual Pb pollution sources in an era of rapidly decreasing industrial pollution. Lead soluble in diluted HNO3 made up 96% of total Pb deposition, with the remaining 4% Pb bound mainly in silicates. Three times higher concentrations of soluble Pb in rime than in snow, and 2.5 times higher concentrations of insoluble Pb in rime than in snow were associated with slightly different Pb isotope ratios. On average, the 206Pb/207Pb ratios in rime were higher than those in snow. Higher mean 206Pb/207Pb ratios of insoluble Pb (1.175) than in soluble Pb (1.165) may indicate an increasing role of geogenic Pb in recent atmospheric deposition. A distinct reversal to more radiogenic 206Pb/207Pb ratios in snow and rime in 2010, compared to literature data from rain-fed Sphagnum peatlands (1800-2000 A.D.), documented a recent decrease in anthropogenic Pb in the atmosphere of Central Europe. Since the early 1980s, Pb concentrations in snow decreased 18 times in the rural south of the Czech Republic, but only twice in the industrial north of the Czech Republic. Isotope signatures indicated that Pb in today's atmospheric deposition is mainly derived from Mesozoic ores mined/processed in Poland and coal combustion in the Czech Republic and Poland.

  6. 206Pb-230Th-234U-238U and 207Pb-235U geochronology of Quaternary opal, Yucca Mountain, Nevada

    USGS Publications Warehouse

    Neymark, Leonid A.; Amelin, Yuri V.; Paces, James B.

    2000-01-01

    U–Th–Pb isotopic systems have been studied in submillimeter-thick outermost layers of Quaternary opal occurring in calcite–silica fracture and cavity coatings within Tertiary tuffs at Yucca Mountain, Nevada, USA. These coatings preserve a record of paleohydrologic conditions at this site, which is being evaluated as a potential high-level nuclear waste repository. The opal precipitated from groundwater is variably enriched in 234U (measured 234U/238U activity ratio 1.124–6.179) and has high U (30–313 ppm), low Th (0.008–3.7 ppm), and low common Pb concentrations (measured 206Pb/204Pb up to 11,370). It has been demonstrated that the laboratory acid treatment used in this study to clean sample surfaces and to remove adherent calcite, did not disturb U–Th–Pb isotopic systems in opal. The opal ages calculated from 206Pb∗/238U and 207Pb∗/235U ratios display strong reverse discordance because of excess radiogenic 206Pb∗ derived from the elevated initial 234U. The data are best interpreted using projections of a new four-dimensional concordia diagram defined by 206Pb∗/238U, 207Pb∗/235U, 234U/238Uactivity, and 230Th/238Uactivity. Ages and initial 234U/238U activity ratios have been calculated using different projections of this diagram and tested for concordance. The data are discordant, that is observed 207Pb∗/235U ages of 170 ± 32 (2σ) to 1772 ± 40 ka are systematically older than 230Th/U ages of 34.1 ± 0.6 to 452 ± 32 ka. The age discordance is not a result of migration of uranium and its decay products under the open system conditions, but a consequence of noninstantaneous growth of opal. Combined U–Pb and 230Th/U ages support the model of slow mineral deposition at the rates of millimeters per million years resulting in layering on a scale too fine for mechanical sampling. In this case, U–Pb ages provide more accurate estimates of the average age for mixed multiage samples than 230Th/U ages, because ages based on shorter

  7. Search for the two-phonon octupole vibrational state in {sup 208}Pb

    SciTech Connect

    Blumenthal, D.J.; Henning, W.; Janssens, R.V.F.

    1995-08-01

    We performed an experiment to search for the two-phonon octupole vibrational state in {sup 208}Pb. Thick targets of {sup 208}Pb, {sup 209}Bi, {sup 58,64}Ni, and {sup 160}Gd were bombarded with 1305 MeV beams of were bombard {sup 208}Pb supplied by ATLAS. Gamma rays were detected using the Argonne-Notre Dame BGO gamma-ray facility, consisting of 12 Compton-suppressed germanium detectors surrounding an array of 50 BGO scintillators. We identified some 30 known gamma rays from {sup 208}Pb in the spectra gated by the 5{sup -} {yields} 3{sup -} and 3{sup -} {yields} 0{sup +} transitions in {sup 208}Pb. In addition, after unfolding these spectra for Compton response, we observed broad coincident structures in the energy region expected for the 2-phonon states. Furthermore, we confirmed the placement of a 2485 keV line observed previously in {sup 207}Pb and find no evidence consistent with the placement of this line in {sup 208}Pb. We are currently in the process of investigating the origin of the broadened lines observed in the spectra, extracting the excitation probability of states in {sup 208}Pb, and determining the relative probability of mutual excitation and neutron transfer in this reaction. An additional experiment is also being performed to collect much higher statistics germanium-germanium coincidence data for the thick {sup 208}Pb target.

  8. Observation of bound and unbound 1- states in 208Pb by particle spectroscopy

    NASA Astrophysics Data System (ADS)

    Heusler, Andreas

    2015-02-01

    Using the Q3D magnetic spectrograph of the Maier-Leibnitz-Labaratorium at Garching (Germany), experiments on the 208Pb(d,d'), the 207Pb(d,p), the resonant and the non-resonant 208Pb(p,p') reactions were performed. The 208Pb(p,p') reaction was investigated near all seven known isobaric analog resonances in 209Bi. The excitation energies of about 300 states in 208Pb at Ex < 8MeV were determined with an accuracy of about 100 eV. The mean distance between states in 208Pb is about 10keV up to the neutron threshold (S(n) = 7368 keV). The number of 1- states observed by particle spectroscopy up to the proton threshold (S(p) = 8.00 MeV) is close to the number predicted by the schematic shell model without residual interaction. The structure of several 1- states is deduced from particle spectroscopy. Four out of the seven lowest 1- states contain about 80% strength of a single configuration.

  9. Deep Sub-Barrier Fusion Enhancement in the {sup 6}He+{sup 206}Pb Reaction

    SciTech Connect

    Penionzhkevich, Yu.E.; Zagrebaev, V.I.; Lukyanov, S.M.; Kalpakchieva, R.

    2006-04-28

    The fusion of {sup 6}He with {sup 206}Pb has been studied at energies close to and below the Coulomb barrier. The experiment was carried out at the Dubna Radioactive Ion Beams complex of FLNR, JINR. The {sup 6}He beam intensity was about 5x10{sup 6} pps, the maximum energy being 60.3{+-}0.4 MeV. The yield of the {sup 210}Po isotope, produced in the 2n-evaporation channel, demonstrates an extremely large enhancement of the sub-barrier fusion cross section as compared with the {sup 4}He+{sup 208}Pb reaction. This enhancement is most likely due to the mechanism of 'sequential fusion' with an intermediate neutron transfer from {sup 6}He to the Pb nucleus with positive Q values.

  10. Using stable lead isotopes to trace heavy metal contamination sources in sediments of Xiangjiang and Lishui Rivers in China.

    PubMed

    Sun, Guo-Xin; Wang, Xin-Jun; Hu, Qin-Hong

    2011-12-01

    Lead isotopes and heavy metal concentrations were measured in two sediment cores sampled in estuaries of Xiangjiang and Lishui Rivers in Hunan province, China. The presence of anthropogenic contribution was observed in both sediments, especially in Xiangjiang sediment. In the Xiangjiang sediment, the lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratio, than natural Pb isotope signature (1.198 and 2.075 for (206)Pb/(207)Pb and (208)Pb/(206)Pb, respectively), indicated a significant input of non-indigenous Pb with low (206)Pb/(207)Pb and high (208)Pb/(206)Pb. The corresponding concentrations of heavy metals (As, Cd, Zn, Mn and Pb) were much higher than natural values, suggesting the contaminations of heavy metals from extensive ore-mining activities in the region.

  11. Feather lead concentrations and207Pb/206Pb ratios reveal lead exposure history of California condors (Gymnogyps californianus)

    USGS Publications Warehouse

    Finkelstein, M.E.; George, D.; Scherbinski, S.; Gwiazda, R.; Johnson, M.; Burnett, J.; Brandt, J.; Lawrey, S.; Pessier, Allan P.; Clark, M.; Wynne, J.; Grantham, And J.; Smith, D.R.

    2010-01-01

    Lead poisoning is a primary factor impeding the survival and recovery of the critically endangered California Condor (Gymnogyps californianus). However, the frequency and magnitude of lead exposure in condors is not well-known in part because most blood lead monitoring occurs biannually, and biannual blood samples capture only ???10% of a bird's annual exposure history. We investigated the use of growing feathers from free-flying condors in California to establish a bird's lead exposure history. We show that lead concentration and stable lead isotopic composition analyses of sequential feather sections and concurrently collected blood samples provided a comprehensive history of lead exposure over the 2-4 month period of feather growth. Feather analyses identified exposure events not evident from blood monitoring efforts, and by fitting an empirically derived timeline to actively growing feathers, we were able to estimate the time frame for specific lead exposure events. Our results demonstrate the utility of using sequentially sampled feathers to reconstruct lead exposure history. Since exposure risk in individuals is one determinant ?? 2010 American Chemical Society.

  12. Feather lead concentrations and (207)Pb/(206)Pb ratios reveal lead exposure history of California Condors (Gymnogyps californianus).

    PubMed

    Finkelstein, M E; George, D; Scherbinski, S; Gwiazda, R; Johnson, M; Burnett, J; Brandt, J; Lawrey, S; Pessier, A P; Clark, M; Wynne, J; Grantham, J; Smith, D R

    2010-04-01

    Lead poisoning is a primary factor impeding the survival and recovery of the critically endangered California Condor (Gymnogyps californianus). However, the frequency and magnitude of lead exposure in condors is not well-known in part because most blood lead monitoring occurs biannually, and biannual blood samples capture only approximately 10% of a bird's annual exposure history. We investigated the use of growing feathers from free-flying condors in California to establish a bird's lead exposure history. We show that lead concentration and stable lead isotopic composition analyses of sequential feather sections and concurrently collected blood samples provided a comprehensive history of lead exposure over the 2-4 month period of feather growth. Feather analyses identified exposure events not evident from blood monitoring efforts, and by fitting an empirically derived timeline to actively growing feathers, we were able to estimate the time frame for specific lead exposure events. Our results demonstrate the utility of using sequentially sampled feathers to reconstruct lead exposure history. Since exposure risk in individuals is one determinant of population health, our findings should increase the understanding of population-level effects from lead poisoning in condors; this information may also be helpful for other avian species potentially impacted by lead poisoning. PMID:20199067

  13. Identification of the sources of metal (lead) contamination in drinking waters in north-eastern Tasmania using lead isotopic compositions.

    PubMed

    Harvey, P J; Handley, H K; Taylor, M P

    2015-08-01

    This study utilises a range of scientific approaches, including lead isotopic compositions, to differentiate unknown sources of ongoing lead contamination of a drinking water supply in north-eastern Tasmania, Australia. Drinking water lead concentrations are elevated above the Australian Drinking Water Guideline (10 μg/L), reaching 540 μg/L in the supply network. Water lead isotopic compositions from the town of Pioneer ((208)Pb/(207)Pb 2.406, (206)Pb/(207)Pb 1.144 to (208)Pb/(207)Pb 2.360, (206)Pb/(207)Pb 1.094) and Ringarooma ((208)Pb/(207)Pb 2.398, (206)Pb/(207)Pb 1.117) are markedly different from the local bedrock ((208)Pb/(207)Pb 2.496, (206)Pb/(207)Pb 1.237). The data show that the lead in the local waters is sourced from a combination of dilapidated drinking water infrastructure, including lead jointed pipelines, end-of-life polyvinyl chloride pipes and household plumbing. Drinking water is being inadvertently contaminated by aging infrastructure, and it is an issue that warrants investigation to limit the burden of disease from lead exposure.

  14. The graphical presentation of lead isotope data for environmental source apportionment.

    PubMed

    Ellam, R M

    2010-07-15

    Lead isotope ratios are widely used to identify original sources of Pb in the environment. Such source apportionment depends on the ability to distinguish potential sources on the basis of their isotopic composition. However, almost all terrestrial Pb is co-linear in some of the plots i.e. (206)Pb/(208)Pb versus (206)Pb/(207)Pb and (206)Pb/(204)Pb versus (206)Pb/(207)Pb commonly presented in the literature. These diagrams are unable to distinguish more than two sources of environmental Pb. Linear trends in such plots are an inevitable consequence of the co-linearity of terrestrial leads and should not be taken necessarily to indicate simple binary mixing of sources. A more reliable test for multiple source mixing can be obtained from plots involving (206)Pb/(204)Pb, (207)Pb/(204)Pb and (208)Pb/(204)Pb and therefore requires measurements of the minor (204)Pb isotope.

  15. Fusion of {sup 9}Li with {sup 208}Pb

    SciTech Connect

    Vinodkumar, A. M.; Loveland, W.; Sprunger, P. H.; Prisbrey, L.; Trinczek, M.; Dombsky, M.; Machule, P.; Kolata, J. J.; Roberts, A.

    2009-11-15

    We have measured the fusion excitation function for the {sup 9}Li+{sup 208}Pb reaction for near-barrier projectile center-of-mass energies of 23.9 to 43.0 MeV using the ISAC2 facility at TRIUMF. The {alpha}-emitting evaporation residues ({sup 211-214}At) were stopped in the {sup 208}Pb target, and their decay was measured. The isotopic yields at each energy were in good agreement with the predictions of a statistical model code (HIVAP). The measured fusion excitation function shows evidence for substantial sub-barrier fusion enhancement not predicted by current theoretical models. There is a suppression of the above barrier cross sections relative to these model predictions. The implications of this measurement for studying the fusion of {sup 11}Li with {sup 208}Pb are discussed.

  16. {sup 208}Pb neutron density: A mean field problem?

    SciTech Connect

    Gmuca, Stefan

    1998-12-21

    The ground-state nuclear densities and radii of {sup 208}Pb doubly-magic nucleus have been evaluated within the framework of the relativistic mean-field approach. It is pointed out that the neutron density and the neutron radius in the RMF approach are quite different from both, the empirical data and the predictions of the Skyrme-Hartree-Fock model.

  17. Energy dependence of pion inelastic scattering from sup 208 Pb

    SciTech Connect

    Oakley, D.S. Lewis and Clark College, Portland, Oregon ); Peterson, R.J. ); Seestrom, S.J.; Morris, C.L.; Plum, M.A. ); Zumbro, J.D. ); Williams, A.L.; Bryan, M.A.; McDonald, J.W.; Moore, C.F. )

    1991-11-01

    Differential cross sections were measured for pion elastic and inelastic scattering from {sup 208}Pb at {ital T}{sub {pi}}=120 and 250 MeV. Energy-dependent neutron- and proton-transition matrix elements for a range of excited states were extracted and tested for consistency, using several structure models.

  18. Spontaneous fission of light californium isotopes produced in 206,207,208Pb + 34,36S reactions; new nuclide 238Cf

    NASA Astrophysics Data System (ADS)

    Lazarev, Yu. A.; Shirokovsky, I. V.; Utyonkov, V. K.; Tretyakova, S. P.; Kutner, V. B.

    1995-02-01

    In bombardments of 206,207,208Pb with 34S and 206Pb with 36S, we identified a new spontaneously fissioning isotope 238Cf with T sf ≈ T {1}/{2} = 21 ± 2 ms and obtained evidence of the production of a new isotope 237Cf with T {1}/{2} = 2.1 ± 0.3 s. The spontaneous-fission (SF) decay mode was established for 240Cf; its SF branch was estimated to be bsf ˜ 2 × 10 -2. We measured also bsf ⩽ 1.4 × 10 -4 for 242Cf and estimated bsf ˜ 10 -1 for 237Cf. The production cross sections of 238Cf in the 206,207,208Pb + 34S reactions were measured to be in the range of 0.3 to 1.1 nb. Finally, we probed the influence of the neutron excess in the N = 20 projectile 36S on cross sections of fusion-evaporation reactions occurring on lead targets.

  19. Lead isotope ratios in tree bark pockets: an indicator of past air pollution in the Czech Republic.

    PubMed

    Conkova, M; Kubiznakova, J

    2008-10-15

    Tree bark pockets were collected at four sites in the Czech Republic with differing levels of lead (Pb) pollution. The samples, spanning 1923-2005, were separated from beech (Fagus sylvatica) and spruce (Picea abies). Elevated Pb content (0.1-42.4 microg g(-1)) reflected air pollution in the city of Prague. The lowest Pb content (0.3-2.6 microg g(-1)) was found at the Kosetice EMEP "background pollution" site. Changes in (206)Pb/(207)Pb and (208)Pb/(206)Pb isotope ratios were in agreement with operation times of the Czech main anthropogenic Pb sources. Shortly after the Second World War, the (206)Pb/(207)Pb isotope ratio in bark pockets decreased from 1.17 to 1.14 and the (208)Pb/(206)Pb isotope ratio increased from 2.12 to 2.16. Two dominant emission sources responsible for these changes, lignite and leaded petrol combustion, contributed to the shifts in Pb isotope ratios. Low-radiogenic petrol Pb ((206)Pb/(207)Pb of 1.11) lead to lower (206)Pb/(207)Pb in bark pockets over time. High-radiogenic lignite-derived Pb ((206)Pb/(207)Pb of 1.18 to 1.19) was detected in areas affected by coal combustion rather than by traffic.

  20. Measurement of internal pairs from {sup 206}Pb

    SciTech Connect

    Ahmad, I.; Back, B.B.; Betts, R.R.

    1995-08-01

    The failure to observe sharp sum-energy lines in measurements of {sup 238}U + {sup 181}Ta and {sup 238}U + {sup 232}Th raises the issue of the correct functioning of APEX under in-beam conditions. Extensive measurements with electron and pair emitting sources were used to demonstrate the resolution and acceptance of APEX, but the possibility remains that some unforeseen background or other effects might compromise the ability to see peaks in-beam. In order to test the functioning of APEX under the most stringent conditions, we also performed a measurement of internal pairs produced in the decay of the 2.648-MeV 3{sup -} state in {sup 206}Pb to the 2{sup +} state at 0.803 MeV. The 3{sup -} state was excited in the {sup 206}Pb + {sup 206}Pb reaction at 5.9 MeV/u with a cross section of roughly 40 mb, resulting in an expected pair cross section of approximately 16 {mu}b. It should be emphasized that this measurement represents a much stricter test of the functioning of the apparatus than the observation of sum-energy lines would represent, as the internal pair measurement requires a Doppler shift correction before the transition can be seen. These data were analyzed and clearly show the expected peak. A Doppler-corrected sum-energy spectrum showing the expected IPC line at 823 keV. At present we are evaluating the acceptance of APEX for events of this type but it is clear that the observed yield is close to expectations.

  1. NMR absolute shielding scale and nuclear magnetic dipole moment of (207)Pb.

    PubMed

    Adrjan, Bożena; Makulski, Włodzimierz; Jackowski, Karol; Demissie, Taye B; Ruud, Kenneth; Antušek, Andrej; Jaszuński, Michał

    2016-06-28

    An absolute shielding scale is proposed for (207)Pb nuclear magnetic resonance (NMR) spectroscopy. It is based on ab initio calculations performed on an isolated tetramethyllead Pb(CH3)4 molecule and the assignment of the experimental resonance frequency from the gas-phase NMR spectra of Pb(CH3)4, extrapolated to zero density of the buffer gas to obtain the result for an isolated molecule. The computed (207)Pb shielding constant is 10 790 ppm for the isolated molecule, leading to a shielding of 10799.7 ppm for liquid Pb(CH3)4 which is the accepted reference standard for (207)Pb NMR spectra. The new experimental and theoretical data are used to determine μ((207)Pb), the nuclear magnetic dipole moment of (207)Pb, by applying the standard relationship between NMR frequencies, shielding constants and nuclear moments of two nuclei in the same external magnetic field. Using the gas-phase (207)Pb and (reference) proton results and the theoretical value of the Pb shielding in Pb(CH3)4, we find μ((207)Pb) = 0.59064 μN. The analysis of new experimental and theoretical data obtained for the Pb(2+) ion in water solutions provides similar values of μ((207)Pb), in the range of 0.59000-0.59131 μN. PMID:27265668

  2. New Neutron Rich Nuclei Near {sup 208}Pb

    SciTech Connect

    Aeystoe, J.; Andreyev, A.; Evensen, A.-H.; Hoff, P.; Huhta, M.; Huyse, M.; ISOLDE Collaboration; Jokinen, A.; Karny, M.; Kugler, E.; Kurpeta, J.; Lettry, J.; Nieminen, A.; Plochocki, A.; Ramdhane, M.; Ravn, H.; Rykaczewski, K.; Szerypo, J.; VanDuppen, P.; Walter, G.; Woehr, A.

    1998-11-13

    The level properties near the stable doubly-magic nuclei formed the experimental grounds for the theoretical description of nuclear structure. However with a departure from the beta-stability line, the classical well-established shell structure might be modified. In particular, it may even vanish for extremely exotic neutron-rich nuclei near the neutron-drip line. Presently, it is impossible to verify such predictions by a direct experimental studies of these exotic objects. However, one may try to observe and understand the evolution of the nuclear structure while departing in the experiment as far as possible from the stable nuclei. An extension of experimental nuclear structure studies towards the nuclei characterized by high neutron excess is crucial for such verifications as well as for the {tau}-process nucleosynthesis scenario. Heavy neutron-rich nuclei, south-east of doubly-magic {sup 208}Pb, were always very difficult to produce and investigate. The nuclei like {sup 218}Po and {sup 214}Pb or {sup 210}Tl marked the border line of known nuclei from the beginning of the radioactivity era for over ninety years. To illustrate the difficulties, one can refer to the experiments employing the on-line mass separator technique. A spallation of heavy targets like {sup 232}Th and {sup 238}U by high-energy protons was proven as a source of heavy neutron-rich nuclei. The isotopes near and beyond doubly-magic {sup 208}Pb were produced too. However, such studies often suffered from an isobaric contamination of much more strongly produced and efficiently released elements like francium or radon and their decay products. A new experimental technique, based on the pulsed release element selective method recently developed at the PS Booster-ISOLDE at CERN [7,8,9] greatly reduces the contamination of these very short-lived {alpha}-emitters (Z {ge} 84) for the isobaric mass chains A=215 to A=218.

  3. Hyperfine Structure Study of Several Lines of 207Pb I

    NASA Astrophysics Data System (ADS)

    Wasowicz, T. J.; Drozdowski, R.; Kwela, J.

    2005-01-01

    The hfs splitting of four lines from the array 6p7s → 6p2 as well as two lines from the array 6p8s → 6p2 of Pb I have been analyzed. A discharge tube containing metallic isotope 207Pb was used as a light source. Our experiment yields hyperfine splitting constants A for some levels of the configurations 6p2 and 6p7s: A(6p2 1D2) = (20.99 ± 0.43) mK, A(6p2 3P2) = (91.37 ± 0.34) mK, A(6p7s 3P1) = (294.16 ± 0.93) mK, A(6p7s 1P1) = (16.45 ± 0.95) mK and A = (202.04 ± 0.48) mK for the level 6p8s 3P1. Our results are compared with recent theory and other experiments.

  4. Multinucleon transfer in the 136Xe+208Pb reaction

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Zhang, Fan; Li, Jingjing; Zhu, Long; Tian, Junlong; Wang, Ning; Zhang, Feng-Shou

    2016-01-01

    The dynamic mechanics in the multinucleon transfer reaction 136Xe+208Pb at an incident energy of Ec .m .=450 MeV is investigated by using the improved quantum molecular dynamics model (ImQMD). The lifetime of the neck directly influences the nucleon exchange and energy dissipation between the projectile and the target. The total-kinetic-energy-mass distributions and excitation energy division of primary binary fragments and the mass distributions of primary fragments at different impact parameters are calculated. The thermal equilibrium between two reaction partners has been observed at the lifetime of a neck larger than 480 fm /c . By using the statistical decay code gemini to describe the de-excitation process of the primary fragments, the isotope production cross sections from Pt to At are compared with the prediction by the dinuclear system and GRAZING model. The calculations indicate that the GRAZING model is suitable for estimating the isotope production cross sections only for Δ Z =-1 to +2; the DNS + gemini calculations underestimate the cross sections in the neutron-rich and neutron-deficient regions; and the ImQMD + gemini calculations give reasonable predictions of the isotope production cross sections for Δ Z =-3 to 0.

  5. New Isomers in the Neutron-Rich Region Beyond 208Pb

    NASA Astrophysics Data System (ADS)

    Gottardo, A.; Valiente-Dobón, J. J.; Benzoni, G.; Gadea, A.; Lunardi, S.; Boutachkov, P.; Bruce, A. M.; Górska, M.; Grebosz, J.; Pietri, S.; Podolyák, Zs.; Pfützner, M.; Regan, P. H.; Weick, H.; Alcántara Núñez, J.; Algora, A.; Al-Dahan, N.; de Angelis, G.; Ayyad, Y.; Alkhomashi, N.; Allegro, P. R. P.; Bazzacco, D.; Benlliure, J.; Bowry, M.; Bracco, A.; Bunce, M.; Camera, F.; Casarejos, E.; Cortes, M. L.; Crespi, F. C. L.; Corsi, A.; Bacelar, A. M. Denis; Deo, A. Y.; Domingo-Pardo, C.; Doncel, M.; Dombradi, Zs.; Engert, T.; Eppinger, K.; Farrelly, G. F.; Farinon, F.; Farnea, E.; Geissel, H.; Gerl, J.; Goel, N.; Gregor, E.; Habermann, T.; Hoischen, R.; Janik, R.; John, P. R.; Klupp, S.; Kojouharov, I.; Kurz, N.; Lenzi, S. M.; Leoni, S.; Mandal, S.; Menegazzo, R.; Mengoni, D.; Million, B.; Modamio, V.; Morales, A. I.; Napoli, D. R.; Naqvi, F.; Nicolini, R.; Nociforo, C.; Prochazka, A.; Prokopowicz, W.; Recchia, F.; Ribas, R. V.; Reed, M. W.; Rudolph, D.; Sahin, E.; Schaffner, H.; Sharma, A.; Sitar, B.; Siwal, D.; Steiger, K.; Strmen, P.; Swan, T. P. D.; Szarka, I.; Ur, C. A.; Walker, P. M.; Wieland, O.; Wollersheim, H.-J.

    2014-03-01

    The region of neutron-rich nuclei beyond 208Pb has been very difficult to explore due to its high mass and exoticity. However, recent experimental improvements allowed one to perform a quite extended isomer decay spectroscopy of these nuclei.

  6. Lead isotopic composition of insoluble particles from widespread mountain glaciers in western China: Natural vs. anthropogenic sources

    NASA Astrophysics Data System (ADS)

    Yu, Guangming; Xu, Jianzhong; Kang, Shichang; Zhang, Qianggong; Huang, Jie; Ren, Qian; Ren, Jiawen; Qin, Dahe

    2013-08-01

    Stable lead (Pb) isotopic fingerprints provide opportunities to trace natural and anthropogenic Pb sources in the environment. In order to evaluate Pb deposition from different sources over mountainous areas of western China, Pb isotopic compositions were characterized from modern aeolian dust in 15 snowpit samples collected from 13 typical mountain glaciers between 2008 and 2010. Most of the snowpits sampled cover more than a whole year of accumulation and overlap with each other on deposition date. Pb isotopic variability among all the samples is small, varying in the range of 18.1399-18.9199 for 206Pb/204Pb, 15.5979-15.8743 for 207Pb/204Pb, 38.2272-39.9453 for 208Pb/204Pb, 1.1605-1.2009 for 206Pb/207Pb and 2.4433-2.5182 for 208Pb/207Pb. Three isotopic plots of the different Pb isotope ratios (207Pb/204Pb vs. 206Pb/204Pb, 208Pb/204Pb vs. 206Pb/204Pb, and 208Pb/207Pb vs. 206Pb/207Pb) in all the samples show identical geographic trends, with more radiogenic in the south and less in the north. This trend is consistent with the distribution of natural dust sources and supports the interpretation of a regional/local source for insoluble particles (IP) to snow/glaciers in this region. Comparison with the Pb isotope results from potential dust sources, however, it shows that the Pb isotopic compositions of IP samples in snow samples are relatively less radiogenic. Parts of these less-radiogenic Pb isotopes are comparable with the ice core results during recent decades, which are shown to be influenced by anthropogenic sources. At sites located along the periphery of western China, the Pb isotopic compositions are much closer to anthropogenic results. Natural and anthropogenic Pb sources are roughly assessed using a simple binary model. The sites with a high anthropogenic fraction are at lower elevations and are relatively close to population centers.

  7. The influence of projectile neutron number in the 208Pb(48Ti, n)255Rf and 208Pb(50Ti, n)257Rf reactions

    SciTech Connect

    Dragojevic, Irena; Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Sudowe, R.; Nitsche, H.

    2008-07-11

    Four isotopes of rutherfordium,254-257Rf, were produced by the 208Pb(48Ti, xn)256-xRf and 208Pb(50Ti, xn)258-xRf reactions (x = 1, 2) at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Excitation functions were measured for the 1n and 2n exit channels. A maximum likelihood technique, which correctly accounts for the changing cross section at all energies subtended by the targets, was used to fit the 1n data to allow a more direct comparison between excitation functions obtained under different experimental conditions. The maximum 1n crosssections of the 208Pb(48Ti, n)255Rf and 208Pb(50Ti, n)257Rf reactions obtained from fits to the experimental data are 0.38 +/- 0.07 nb and 40 +/-5 nb, respectively. Excitation functions for the 2n exit channel were also measured, with maximum cross sections of nb for the 48Ti induced reaction, and 15.7 +/- 0.2 nb for the 50Ti induced reaction. The impact of the two neutron difference in the projectile on the 1n cross section is discussed. The results are compared to the Fusion by Diffusion model developed by Swiatecki, Wilczynska, and Wilczynski.

  8. Measurements of neutron capture cross section for {sup 207,208}Pb

    SciTech Connect

    Segawa, M.; Toh, Y.; Harada, H.; Kitatani, F.; Koizumi, M.; Fukahori, T.; Iwamoto, N.; Iwamoto, O.; Oshima, M.; Hatsukawa, Y.; Nagai, Y.; Igashira, M.; Kamada, S.; Tajika, M.

    2014-05-02

    The neutron capture cross sections for {sup 207,208}Pb have been measured in the neutron energy region from 10 to 110 keV. The γ-rays cascaded from a capture state to the ground state or low-lying states of {sup 208,209}Pb were observed for the first time, using an anti-Compton Nal(Tl) spectrometer and a TOF method. The observed discrete γ-ray energy spectra enabled us to determine neutron capture cross sections for {sup 207,208}Pb with small systematic errors, since we could distinguish γ-ray of {sup 207,208}Pb(n,γ) reactions from background γ-ray with use of the γ-ray spectra. The obtained cross sections include both contributions of resonance and direct capture components different from the previous TOF measurements.

  9. Sensitivity of the electric dipole polarizability to the neutron skin thickness in {sup 208}Pb

    SciTech Connect

    Roca-Maza, X.; Agrawal, B. K.; Colo, G.; Nazarewicz, W.; Paar, N.; Piekarewicz, J.; Reinhard, P.-G.; Vretenar, D.

    2012-10-20

    The static dipole polarizability, {alpha}{sub D}, in {sup 208}Pb has been recently measured with highresolution via proton inelastic scattering at the Research Center for Nuclear Physics (RCNP) [1]. This observable is thought to be intimately connected with the neutron skin thickness, r{sub skin}, of the same nucleus and, more fundamentally, it is believed to be associated with the density dependence of the nuclear symmetry energy. The impact of r{sub skin} on {alpha}{sub D} in {sup 208}Pb is investigated and discussed on the basis of a large and representative set of relativistic and non-relativistic nuclear energy density functionals (EDF) [2].

  10. Discrimination of the Cigarettes Geographical Origin by DRC-ICP-MS Measurements of Pb Isotope Compositions

    NASA Astrophysics Data System (ADS)

    Guo, W.; Hu, S.; Jin, L.

    2014-12-01

    Trace Pb are taken up with the same isotopic ratios as is present in the source soil, and the isotopic composition of Pb could used to reflect these sources and provide powerful indicators of the geographic origin of agriculture products derived from vegetative matter. We developed a simple and high throughput method, which based on DRC-ICP-MS for determination of Pb isotope ratios for discriminating the geographic origin of cigarettes. After acid digestion procedure, the cigarette digested solutions were directly analyzed by ICP-QMS with a DRC pressurized by the non-reactive gas Ne. In the DRC, Ne molecules collision with Pb ions and improves Pb isotope ratios precision 3-fold, which may be due to the collisional dampling smoothes out the ion beam fluctuations. Under the optimum DRC rejection parameter Q (RPq = 0.45), the main matrix components (K, Na, Ca, Mg, Al, Fe etc.) originating from cigarettes were filtered out. Mass discrimination of 208Pb/206Pb ratio in Ne DRC mode increased 0.3% compared to the standard mode, the mass bias due to the in-cell Ne gas collision can be accurately corrected by NIST 981 Pb isotope standard. This method was verified by a tobacco reference material CTV-OTL-2. Results of 208Pb/206Pb and 207Pb/206Pb were 2.0848 ± 0.0028 (2δ) and 0.8452 ± 0.0011 (2δ) for CTA-VTL-2, which were agreed with the literature values (208Pb/206Pb = 2.0884 ± 0.0090 and 207Pb/206Pb = 0.8442 ± 0.0032). The precision of Pb isotope ratios (208Pb/206Pb and 207Pb/206Pb) for the cigarette samples are ranged from 0.01 to 0.08% (N = 5). It has sufficient precision to discriminate 91 different brand cigarettes originated from four different geographic regions (Shown in Fig).

  11. Elastic scattering of 17O+208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Torresi, D.; Strano, E.; Mazzocco, M.; Boiano, A.; Boiano, C.; Di Meo, P.; La Commara, M.; Manea, C.; Nicoletto, M.; Grebosz, J.; Guglielmetti, A.; Molini, P.; Parascandolo, C.; Pierroutsakou, D.; Signorini, C.; Soramel, F.; Toniolo, N.; Filipescu, D.; Gheorghe, A.; Glodariu, T.; Jeong, S.; Kim, Y. H.; Lay, J. A.; Miyatake, H.; Pakou, A.; Sgouros, O.; Soukeras, V.; Stroe, L.; Vitturi, A.; Watanabe, Y.; Zerva, K.

    2016-05-01

    Within the frame of the commissioning of a new experimental apparatus EXPADES we undertook the measurement of the elastic scattering angular distribution for the system 17O+208Pb at energy around the Coulomb barrier. The reaction dynamics induced by loosely bound Radioactive Ion Beams is currently being extensively studied [4]. In particular the study of the elastic scattering process allows to obtain direct information on the total reaction cross section of the exotic nuclei. In order to understand the effect of the low binding energy on the reaction mechanism it is important to compare radioactive weakly bound nuclei with stable strongly-bound nuclei. In this framework the study of the 17O+208Pb elastic scattering can be considered to be complementary to a previous measurement of the total reaction cross section for the system 17F+208Pb at energies of 86, 90.4 MeV [5, 6]. The data will be compared with those obtained for the neighboring systems 16,18O+208Pb and others available in literature.

  12. Pb isotope composition in lichens and aerosols from eastern Sicily: Insights into the regional impact of volcanoes on the environment

    SciTech Connect

    Monna, F. ); Aiuppa, A.; Varrica, D. ); Dongarra, G. CNR, Palermo . Istituto Geochimica dei Fluidi)

    1999-08-01

    A total of 25 lichen thalli of Parmelia conspersa (Ehrh), collected at Vulcano island and at Mt. Etna, during a one-year biogeochemical survey, were analyzed for Pb, br, Al, Sc,[sup 206]Pb/[sup 207]Pb, and [sup 208]Pb/[sup 206]Pb ratios. Lead isotope ratios were also measured on aerosol samples from urban areas and industrial sites of Sicily. The observed [sup 206]Pb/[sup 207]Pb range for urban and industrial aerosols matches the anthropogenic signature. Lichens instead, are closer to the compositional field of [sup 206]Pb rich geogenic sources. This natural input is more evident at Vulcano island than at Mt. Etna, where the anthropogenic activities are considerably more effective. On the basis of lead isotope data, Pb/Br ratios and calculated lead enrichment factors, a natural lead pollution from volcanoes is suggested. Volcanic lead contribution ranges from 10 to 30% at Mt. Etna to 10--80% at Vulcano island.

  13. A precise 232Th-208Pb chronology of fine-grained monazite: Age of the Bayan Obo REE-Fe-Nb ore deposit, China

    USGS Publications Warehouse

    Wang, Jingyuan; Tatsumoto, M.; Li, X.; Premo, W.R.; Chao, E.C.T.

    1994-01-01

    We have obtained precise Th-Pb internal isochron ages on monazite and bastnaesite for the world's largest known rare earth elements (REE)-Fe-Nb ore deposit, the Bayan Obo of Inner Mongolia, China. The monazite samples, collected from the carbonate-hosted ore zone, contain extremely small amounts of uranium (less than 10 ppm) but up to 0.7% ThO2. Previous estimates of the age of mineralization ranged from 1.8 to 0.255 Ga. Magnetic fractions of monazite and bastnaesite samples (<60-??m size) showed large ranges in 232Th 204Pb values (900-400,000) and provided precise Th-Pb internal isochron ages for paragenetic monazite mineralization ranging from 555 to 398 Ma within a few percent error (0.8% for two samples). These results are the first indication that REE mineralization within the giant Bayan Obo ore deposit occurred over a long period of time. The initial lead isotopic compositions (low 206Pb 204Pb and high 208Pb 204Pb) and large negative ??{lunate}Nd values for Bayan Obo ore minerals indicate that the main source(s) for the ores was the lower crust which was depleted in uranium, but enriched in thorium and light rare earth elements for a long period of time. Zircon from a quartz monzonite, located 50 km south of the ore complex and thought to be related to Caledonian subduction, gave an age of 451 Ma, within the range of monazite ages. Textural relations together with the mineral ages favor an epigenetic rather than a syngenetic origin for the orebodies. REE mineralization started around 555 Ma (disseminated monazite in the West, the Main, and south of the East Orebody), but the main mineralization (banded ores) was related to the Caledonian subduction event ca. 474-400 Ma. ?? 1994.

  14. Enhanced E1 transitions and {alpha}+{sup 208}Pb(3{sup -}) clustering in {sup 212}Po

    SciTech Connect

    Suzuki, Y.; Ohkubo, S.

    2010-10-15

    We formulate a model for {sup 212}Po, based on the coupled-channels of {alpha}+{sup 208}Pb(0{sup +}) and {alpha}+{sup 208}Pb(3{sup -}) in which the {alpha}-Pb interaction contains scalar, quadrupole, and octupole terms. The model reproduces the recently observed enhanced E1 transitions from the several new negative-parity levels to the yrast states. Because these data are hard to understand in the shell model, this success gives a strong support for a unique role of {alpha}+{sup 208}Pb(3{sup -}) clustering in {sup 212}Po.

  15. Understanding the partitioning processes of mobile lead in soakaway sediments using sequential extraction and isotope analysis.

    PubMed

    Kumar, Manish; Furumai, Hiroaki; Kurisu, Futoshi; Kasuga, Ikuro

    2009-01-01

    Lead (Pb) isotopic data were used in this study to first distinguish the partitioning of anthropogenic and natural lead in different fractions, obtained by BCR sequential extraction, and then to anticipate their mixing process in the soakaway sediment of artificial infiltration facilities (AIF). Total metal content was found higher in soakaway sediment samples than that of soil. The lowest (206)Pb/(207)Pb ratios were mostly observed in exchangeable fractions of soil and sediment samples, while residual fractions mostly showed the highest (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios than those of other fractions. In general, both ratios were higher in the soil than those of sediments. Further among soil samples, residual fraction of bottom soil exhibited higher ratios than surface soil indicating higher contribution of natural lead with depth. In addition, the difference in Pb content, partitioning and its isotope signature among four sediment samples were also investigated considering their sampling locations. The plot of (206)Pb/(207)Pb versus (208)Pb/(207)Pb showed two well demarcated cluster formations by soil and sediments samples that describe the partitioning between anthropogenic and natural lead; and some points falling in between soil and sediment samples pertinently illustrated the mixing processes between these two different pools of lead.

  16. Effects of reduced lead deposition on pied flycatcher (Ficedula hypoleuca) nestlings: tracing exposure routes using stable lead isotopes.

    PubMed

    Berglund, Asa M M; Klaminder, Jonatan; Nyholm, N Erik I

    2009-01-01

    To what extent the lead burden of birds living in strongly contaminated ecosystems is responding to decreased atmospheric lead deposition is not well known. In this study, we measured lead concentrations and stable lead isotope ratios (206pb/207Pb and 208Pb/207Pb) in liver and feces from pied flycatcher nestlings (Ficedula hypoleuca) along a 90 km pollution gradient from the Rönnskär smelter in northern Sweden. Changes in lead concentration in the birds from 1984 to 2006 were used for assessing the recovery of the environment following reduced lead emissions at the smelter. The 206Pb/207Pb and 208Pb/207Pb ratios were used to identify lead sources to the birds. Lead concentrations in liver and feces have decreased since the 1980s, typically by 9-15% (liver) and 18-40% (feces) as a result of a 98% emission reduction. This relatively weak recovery is explained by a transfer of old lead contaminants accumulated in soil to the birds via their prey, which was evident by a 206Pb/207Pb ratio in liver tissue (1.15 +/- 0.01) that overlapped with the ratio in ants (1.16 +/- 0.01) and organic soil horizon (1.17 +/- 0.01) rather than the current atmospheric lead pollution (1.11 +/- 0.01). Our findings suggest that insectivorous birds living around smelters may remain contaminated decades after ceased emissions.

  17. The characteristic of Pb isotopic compositions in different chemical fractions in sediments from Three Gorges Reservoir, China.

    PubMed

    Han, Lanfang; Gao, Bo; Wei, Xin; Gao, Li; Xu, Dongyu; Sun, Ke

    2015-11-01

    To explore the distribution and sources of Pb within the Three Gorges Reservoir (TGR), Pb concentrations and isotope ratios were measured in sediment cores collected from one mainstream and three tributaries. The results showed that sediments contained an average of 43.54 mg kg(-1) of Pb, roughly 1.6 times higher than the geochemical background concentration. Mainstream sediments showed higher average Pb concentrations but slightly less (206)Pb/(207)Pb and more radiogenic (207)Pb/(208)Pb ratios than all tributaries. Most Pb occurred in reducible phases, with much less in exchangeable and oxidizable fractions; thus, Fe-Mn oxides may be the major sink of anthropogenic Pb. Bi-plots of (206)Pb/(207)Pb versus Pb content, and of (206)Pb/(207)Pb versus (207)Pb/(208)Pb, indicated that coal combustion was the predominant anthropogenic Pb source for exchangeable, reducible, and oxidizable fractions, while residual Pb mainly occurred naturally. The average percentage of coal consumption contribution was 61.1% for the Pb contamination in sediments in the lower reaches in the TGR region.

  18. Measurement of the 208Pb(52Cr, n)259Sg Excitation Function

    SciTech Connect

    Folden III, C.M.; Dragojevic, I.; Dullmann, Ch.E.; Eichler, R.; Garcia, M.A.; Gates, J.M.; Nelson, S.L.; Sudowe, R.; Gregorich, K.E.; Hoffman, D.C.; Nitsche, H.

    2010-03-19

    The excitation function for the 208Pb(52Cr, n)259Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from 259Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the 208Pb(52Cr, 2n)258Sg reaction was obtained, and an improved 258Sg half-life of ms was calculated by combining all available experimental data.

  19. Theoretical study on neutron distribution of 208Pb by parity-violating electron scattering

    NASA Astrophysics Data System (ADS)

    Liu, Jian; Zhang, Cun; Ren, Zhong-Zhou; Xu, Chang

    2016-03-01

    The precise determination of neutron distribution has important implications for both nuclear structure and nuclear astrophysics. The purpose of this paper is to study the characteristics of neutron distribution of 208Pb by parity-violating electron scattering (PVS). Parity-violating asymmetries of 208Pb with different types of neutron skins are systematically calculated and compared with the experimental data of PREx. The results indicate that the PVS experiments are very sensitive to the nuclear neutron distributions. From further PVS measurements, detailed information on nuclear neutron distributions can be extracted. Supported by the National Natural Science Foundation of China (11505292, 11175085, 11235001, 11447226), by the Shandong Provincial Natural Science Foundation, China (BS2014SF007), by the Fundamental Research Funds for the Central Universities (15CX02072A, 15CX02070A, 15CX05026A, 13CX10022A, 14CX02157A).

  20. Atomic mass measurements of short-lived nuclides around the doubly-magic 208Pb

    NASA Astrophysics Data System (ADS)

    Weber, C.; Audi, G.; Beck, D.; Blaum, K.; Bollen, G.; Herfurth, F.; Kellerbauer, A.; Kluge, H.-J.; Lunney, D.; Schwarz, S.

    2008-04-01

    Accurate atomic mass measurements of neutron-deficient and neutron-rich nuclides around the doubly-magic 208Pb and of neutron-rich cesium isotopes were performed with the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The masses of 145,147Cs, 181,183Tl, 186Tl m, 187Tl m, 196Tl m, 205Tl, 197Pb m, 208Pb, 190-197Bi, 209,215,216Bi, 203,205,229Fr, and 214,229,230Ra were determined. The obtained relative mass uncertainty in the range of 2×10 to 2×10 is not only required for safe identification of isomeric states but also allows mapping the detailed structure of the mass surface. A mass adjustment procedure was carried out and the results included into the Atomic Mass Evaluation. The resulting separation energies are discussed and the mass spectrometric and laser spectroscopic data are examined for possible correlations.

  1. Production and identification of new, neutron-rich nuclei in the [sup 208]Pb region

    SciTech Connect

    Rykaczewski, K. ); Szerypo, J.; Evensen, A.-H.; Kugler, E.; Lettry, J.; Ravn, H. ); Kurpeta, J.; Pkochocki, A.; Karny, M.; Szerypo, J. ); Szerypo, J. ); Andreyev, H.; Huyse, M.; Wo uml; hr, A. ); Aystuml, J.; Nieminen, A.; Huhta, M. ); Walter, G. ) Hoff, P. )

    1998-12-01

    The recently developed methods allowing the experimental studies on new neutron-rich nuclei beyond doubly-magic [sup 208]Pb are briefly described. An identification of new neutron-rich isotopes [sup 215]Pb and [sup 217]Bi, and new decay properties of [sup 216]Bi studied by means of a pulsed release element selective technique at PS Booster-ISOLDE are reported. [copyright] [ital 1998 American Institute of Physics.

  2. Scattering of {sup 8}He on {sup 208}Pb at 22 MeV

    SciTech Connect

    Marquinez-Duran, G.; Sanchez-Benitez, A. M.; Martel, I.; Berjillos, R.; Duenas, J. A.; Parkar, V. V.; Acosta, L.; Rusek, K.; Alvarez, M. A. G.; Gomez-Camacho, J.; Borge, M. J. G.; Cruz, C.; Cubero, M.; Pesudo, V.; Tengblad, O.; Chbihi, A.; Fernandez-Garcia, J. P.; Moro, A. M.; Fernandez-Martinez, B.; Labrador, J. A.; and others

    2013-06-10

    The skin nucleus {sup 8}He is investigated by measuring the angular distribution of the elasticly scattered {sup 8}He and the {sup 6,4}He fragments produced in the collision with a {sup 208}Pb target at 22 MeV, just above the Coulomb barrier. The experiment was carried out at SPIRAL/GANIL in 2010. Here we present preliminary results for the elastic scattering.

  3. Complete identification of states in 208Pb below Ex=6.2 MeV

    NASA Astrophysics Data System (ADS)

    Heusler, A.; Jolos, R. V.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.; von Brentano, P.

    2016-05-01

    The Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium of the Ludwig-Maximilians-Universität München and the Technische Universität München (Garching, Germany), was used to study the 208Pb(p ,p' ) , 206,207,208Pb (d,p), and 208Pb(d ,d' ) reactions. One hundred fifty-one states at Ex<6.20 MeV in 208Pb are identified and spin and parity assigned. Four states are newly identified and new spins and/or parities are assigned to 25 states. Tentative spin assignments are done to five states at 5.90

  4. Neutron skin of (208)Pb, nuclear symmetry energy, and the parity radius experiment.

    PubMed

    Roca-Maza, X; Centelles, M; Viñas, X; Warda, M

    2011-06-24

    A precise determination of the neutron skin Δr(np) of a heavy nucleus sets a basic constraint on the nuclear symmetry energy (Δr(np) is the difference of the neutron and proton rms radii of the nucleus). The parity radius experiment (PREX) may achieve it by electroweak parity-violating electron scattering (PVES) on (208)Pb. We investigate PVES in nuclear mean field approach to allow the accurate extraction of Δr(np) of (208)Pb from the parity-violating asymmetry A(PV) probed in the experiment. We demonstrate a high linear correlation between A(PV) and Δr(np) in successful mean field forces as the best means to constrain the neutron skin of (208)Pb from PREX, without assumptions on the neutron density shape. Continuation of the experiment with higher precision in A(PV) is motivated since the present method can support it to constrain the density slope of the nuclear symmetry energy to new accuracy.

  5. Complete Electric and Magnetic Dipole Response of 208Pb from Zero-Degree Inelastic Proton Scattering

    NASA Astrophysics Data System (ADS)

    von Neumann-Cosel, P.

    2015-11-01

    Small-angle polarized proton scattering including 0° off 208Pb has been studied at the RCNP cyclotron with high energy resolution of the order of 25 keV (FWHM). The complete E1 strength distribution from 5 to 20 MeV could be extracted from the data and is found to agree well with available data. New E1 strength is found in the energy region above threshold inacessible in previous experiments. The total E1 polarizability as well as the properties of the pygmy dipole resonance could be determined with high precision providing important experimental constraints on the neutron skin thickness in 208Pb and the symmetry energy of neutron-rich matter. Additionally, information on the spin-M1 strength in 208Pb was obtained. Assuming dominance of the central spin-isospinflip part of the effective proton-nucleus interaction, the B(M1) transition strength can be derived. It corresponds well with data from electromagnetic probes indicating that the reaction can provide information on the poorly known spin-M1 resonance in heavy nuclei.

  6. Identification of the 0+ proton pairing vibration state in the doubly magic nucleus 208Pb by particle spectroscopy

    NASA Astrophysics Data System (ADS)

    Heusler, A.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.; von Brentano, P.

    2015-04-01

    Among about 150 levels below Ex=5.86 MeV in 208Pb listed by the Nuclear Data Sheets as of 2007, most levels were recently identified as particle-hole states. All natural parity states excited by the 208Pb(α ,α') reaction are identified, two of them are newly identified. The state at Ex=5667 keV is identified as the 0+ proton pairing vibration state. Based on the analysis of data from the Pb 206 ,207 ,208 (d ,p ) ,208Pb(d ,d') , and 208Pb(p ,p') reactions obtained with the Q3D magnetic spectrograph of the Maier-Leibnitz-Laboratorium at Garching (Germany) at scattering angles 15° ≤Θ ≤138° and bombarding energies Ed=22 ,24 MeV and 14.8 208Pb(p ,p') and the 208Pb(d ,d') reactions is about 1 μ b/sr . A new state at Ex=5042 ±3 keV is suggested to have the spin of 2+. The 0+ neutron pairing vibration state at Ex=4868 keV and the 0+ member of the double-octupole multiplet at Ex=5241 keV are verified by the nonresonant 208Pb(p ,p') and 208Pb(d ,d') reactions with cross sections of around 3 μ b /sr .

  7. The application of lead isotope ratios in the Antarctic macroalga Iridaea cordata as a contaminant monitoring tool.

    PubMed

    Runcie, John W; Townsend, Ashley T; Seen, Andrew J

    2009-07-01

    Lead (Pb) isotope ratios were measured in the marine macroalga Iridaea cordata collected from four locations in the Windmill Islands, East Antarctica. Based on the masses of thalli collected, samples analysed in this study were likely to be a mixture of one and two year old thalli. For a sample of thalli of various ages (<12 months to 2 years old) from the same site there was no apparent variation in Pb concentration or Pb isotope ratio with thallus mass/age, indicating that contaminant sources had been constant over the lifetime of the thalli sampled. I.cordata samples close to the Thala Valley waste disposal site (Brown Bay Inner) near the Australian Station, Casey, displayed isotopic signatures ((208)Pb/(204)Pb 35.99; (206)Pb/(207)Pb 1.066; n=3; average values shown) trending towards that possessed by major Australian Pb sources (Broken Hill and Mt Isa, (208)Pb/(204)Pb 35.60; (206)Pb/(207)Pb 1.041) suggesting that these samples had been exposed to anthropogenic Pb originating from the Thala Valley waste disposal site. Material collected hundreds of metres from the tip location at Brown Bay Outer had isotopic values ((208)Pb/(204)Pb 36.32; (206)Pb/(207)Pb 1.088; n=10) intermediate between Brown Bay Inner and sites further from the contaminant source at Sparkes Bay and Wilkes ((208)Pb/(204)Pb 36.46; (206)Pb/(207)Pb 1.094; n=4) showing that contaminant transport was predominantly restricted to Brown Bay Inner. This study demonstrates that the isotope ratios of Pb in marine macroalgae can provide valuable information as to the origin and extent of heavy metal flux in a marine environment.

  8. Radiogenic lead with dominant content of {sup 208}Pb: New coolant and neutron moderator for innovative nuclear reactors

    SciTech Connect

    Shmelev, A. N.; Kulikov, G. G.; Kryuchkov, E. F.; Apse, V. A.; Kulikov, E. G.

    2012-07-01

    The advantages of radiogenic lead with dominant content of {sup 208}Pb as a reactor coolant with respect to natural lead are caused by unique nuclear properties of {sup 208}Pb which is a double-magic nucleus with closed proton and neutron shells. This results in significantly lower micro cross section and resonance integral of radiative neutron capture by {sup 208}Pb than those for numerous light neutron moderators. The extremely weak ability of {sup 208}Pb to absorb neutrons results in the following effects. Firstly, neutron moderating factor (ratio of scattering to capture cross sections) is larger than that for graphite and light water. Secondly, age and diffusion length of thermal neutrons are larger than those for graphite, light and heavy water. Thirdly, neutron lifetime in {sup 208}Pb is comparable with that for graphite, beryllium and heavy water what could be important for safe reactor operation. The paper presents some results obtained in neutronics and thermal-hydraulics evaluations of the benefits from the use of radiogenic lead with dominant content of {sup 208}Pb instead of natural lead as a coolant of fast breeder reactors. The paper demonstrates that substitution of radiogenic lead for natural lead can offer the following benefits for operation of fast breeder reactors. Firstly, improvement of the reactor safety thanks to the better values of coolant temperature reactivity coefficient and, secondly, improvement of some thermal-hydraulic reactor parameters. Radiogenic lead can be extracted from thorium sludge without isotope separation as {sup 208}Pb is a final isotope in the decay chain of {sup 232}Th. (authors)

  9. Study of the cross section determination with the PRISMA spectrometer: The 40Ar + 208Pb case

    NASA Astrophysics Data System (ADS)

    Mijatović, T.; Szilner, S.; Corradi, L.; Montanari, D.; Pollarolo, G.; Fioretto, E.; Gadea, A.; Goasduff, A.; Jelavić Malenica, D.; Mărginean, N.; Montagnoli, G.; Scarlassara, F.; Soić, N.; Stefanini, A. M.; Ur, C. A.; Valiente-Dobón, J. J.

    2016-04-01

    The PRISMA spectrometer's response function was successfully applied to match three angular and magnetic settings over a wide angular range for measurements of quasi-elastic reactions in 40Ar + 208Pb . The absolute scale of cross sections has been obtained by using the Rutherford cross section at the forward angles and the information from the energy distributions measured with the spectrometer without and with coincidences with the CLARA γ-array. The semi-classical model GRAZING has been used to test the unfolding procedure and for comparison with the corrected cross sections.

  10. Confirmation of production of element 110 by the (208)Pb(64-Ni,n) reaction

    SciTech Connect

    Ginter, T.N.; Gregorich, K.E.; Loveland, W.; Lee, D.M.; Kirbach, U.W.; Sudowe, R.; Folden III, C.M.; Patin, J.B.; Seward, N.; Wilk, P.A.; Zielinski, P.M.; Aleklett, K.; Eichler, R.; Nitsche, H.; Hoffman, D.C.

    2002-12-08

    We report the experimental confirmation of the production of element110. In the bombardment of a 208Pb target with a 309~MeV 64Ni beam, we have observed two chains of time- and position-correlated events. Each chain consisted of the implantation of an evaporation residue followed by the emission of alpha-particles. We attribute these two chains to the decay of 271-110 produced with a cross section of 8.3 (+11/-5.3)pb.

  11. Elastic scattering of {sup 9}Li on {sup 208}Pb at energies around the Coulomb barrier

    SciTech Connect

    Cubero, M.; Fernandez-Garcia, J. P.; Alvarez, M. A. G.; Lay, J. A.; Moro, A. M.; Acosta, L.; Martel, I.; Sanchez-Benitez, A. M.; Alcorta, M.; Borge, M. J. G.; Tengblad, O.; Buchmann, L.; Shotter, A.; Walden, P.; Diget, D. G.; Fulton, B.; Fynbo, H. O. U.; Galaviz, D.; Gomez-Camacho, J.; Mukha, I.

    2011-10-28

    We have studied the dynamical effects of the halo structure of {sup 11}Li on the scattering on heavy targets at energies around the Coulomb barrier. This experiment was performed at ISAC-II at TRIUMF with a world record in production of the post-accelerated {sup 11}Li beam. As part of this study we report here on the first measurement of the elastic cross section of the core nucleus, i.e. {sup 9}Li on {sup 208}Pb, at energies around the Coulomb barrier. A preliminary optical model analysis has been performed in order to extract a global optical potential to describe the measured angular distributions.

  12. Multinucleon transfer processes in {sup 40}Ca+{sup 208}Pb

    SciTech Connect

    Szilner, S.; Corradi, L.; Behera, B.R.; Fioretto, E.; Gadea, A.; Latina, A.; Stefanini, A.M.; Trotta, M.; Vinodkumar, A.M.; Wu, Y.; Pollarolo, G.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Haas, F.

    2005-04-01

    Multinucleon transfer reactions in {sup 40}Ca+{sup 208}Pb have been studied at bombarding energies close to the Coulomb barrier. Projectilelike fragments have been identified in nuclear mass and charge with a time-of-flight spectrometer. Angular and total kinetic energy loss distributions and inclusive cross sections have been compared with those of semiclassical models. The analysis shows that a successive transfer mechanism of single nucleons does not account for the data, and a direct nucleon pair transfer has to be included in the description. Nucleon evaporation effects are taken into account.

  13. Sub-Barrier Fusion in the HI + 208Pb Systems and Nuclear Potentials for Cluster Decay

    SciTech Connect

    Sagaidak, R.N.; Tretyakova, S.P.; Khlebnikov, S.V.; Ogloblin, A.A.; Rowley, N.

    2005-11-21

    Near-barrier fusion excitation functions for the 12,14C, 16,18O + 208Pb reactions have been analyzed in the framework of the barrier-passing model using different forms of the nuclear potential and the phenomenology of a fluctuating barrier. The best-fit fusion potentials were used to estimate cluster decay probabilities from the corresponding ground states of Ra and Th, i.e., for the inverse decay process. The analysis supports the 'alpha-decay-like' scenario for carbon and oxygen emission from these nuclei.

  14. Elastic neutron scattering at 96 MeV from 12C and 208Pb

    NASA Astrophysics Data System (ADS)

    Klug, J.; Blomgren, J.; Ataç, A.; Bergenwall, B.; Hildebrand, A.; Johansson, C.; Mermod, P.; Nilsson, L.; Pomp, S.; Tippawan, U.; Elmgren, K.; Olsson, N.; Jonsson, O.; Prokofiev, A. V.; Renberg, P.-U.; Nadel-Turonski, P.; Dangtip, S.; Phansuke, P.; Österlund, M.; Le Brun, C.; Lecolley, J. F.; Lecolley, F. R.; Louvel, M.; Marie-Noury, N.; Schweitzer, C.; Eudes, Ph.; Haddad, F.; Lebrun, C.; Koning, A. J.; Bauge, E.; Delaroche, J. P.; Girod, M.; Ledoux, X.; Romain, P.; Madland, D. G.; Amos, K.; Deb, P. K.; Karataglidis, S.; Crespo, R.; Moro, A. M.

    2003-03-01

    A facility for detection of scattered neutrons in the energy interval 50 130 MeV, scattered nucleon detection assembly, has recently been installed at the 20 180 MeV neutron beam line of The Svedberg Laboratory, Uppsala. First results on elastic neutron scattering from 12C and 208Pb at 96 MeV incident neutron energy are presented. This experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. The results are compared with modern optical model predictions.

  15. Uncertainty analysis of 208Pb neutron skin predictions with chiral interactions

    DOE PAGES

    Sammarruca, Francesca

    2015-09-14

    Here, we report predictions for the neutron skin in 208Pb using chiral two- and three-body interactions at increasing orders of chiral effective field theory and varying resolution scales. Closely related quantities, such as the slope of the symmetry energy, are also discussed. As a result, the sensitivity of the skin to just pure neutron matter pressure when going from order 2 to order 4 of chiral effective theory is singled out in a set of calculations that employ an empirical equation of state for symmetric nuclear matter.

  16. Weak-coupling calculations in the /sup 208/Pb core region

    SciTech Connect

    McGrory, J.B.

    1981-01-01

    The structure of Tl and Hg isotopes near the /sup 208/Pb core is discussed in terms of a weak-coupling model where low-lying proton-hole states are coupled to low-lying neutron-hole states. The even Pb isotopes are first discussed in terms of a generalized seniority-2 approximation which is shown to be very accurate. The weak-coupling results are not satisfactory, and it is suggested that the defeat may be in the n-p interaction.

  17. The pairing correlation study in the {sup 40}Ar+{sup 208}Pb reaction

    SciTech Connect

    Mijatović, T. Szilner, S.; Malenica, D. Jelavić; Prepolec, L.; Soić, N.; Tokić, V.; Corradi, L.; Fioretto, E.; Goasduff, A.; Stefanini, A. M.; Dobón, J. J. Valiente; Montanari, D.; Courtin, S.; Haas, F.; Montagnoli, G.; Scarlassara, F.; Ur, C. A.; Pollarolo, G.

    2015-10-15

    The multinucleon transfer reaction {sup 40}Ar+{sup 208}Pb has been measured at E{sub lab} = 260 MeV with the large solid angle magnetic spectrometer PRISMA. Mass and charge yields, differential and total cross sections, total kinetic energy loss distributions of different channels were simultaneously studied. Angular distributions were measured in a wide angular range by matching three different angular settings of the spectrometer. Absolute cross sections were obtained after the response function of the spectrometer was evaluated. These cross sections for different transfer channels allow the discussion of the role played by nucleon-nucleon correlations.

  18. Measurement of the Neutron Radius of 208Pb Through Parity-Violation in Electron Scattering

    DOE PAGES

    Abrahamyan, Sergey; Albataineh, Hisham; Aniol, Konrad; Armstrong, David; Armstrong, Whitney; Averett, Todd; Babineau, Benjamin; Barbieri, A.; Bellini, Vincenzo; Beminiwattha, Rakitha; et al

    2012-03-15

    We report the first measurement of the parity-violating asymmetry APV in the elastic scattering of polarized electrons from 208Pb. APV is sensitive to the radius of the neutron distribution (Rn). The result APV = 0.656 ± 0.060 (stat) ± 0.013 (syst) corresponds to a difference between the radii of the neutron and proton distributions Rn-Rp = 0.33-0.18+0.16 fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

  19. Electric dipole response of {sup 208}Pb and constraints on the symmetry energy

    SciTech Connect

    Tamii, A.

    2014-05-02

    The electric dipole (E1) response of {sup 208}Pb has been precisely determined by measuring polarized proton inelastic scattering at very forward angles including zero degrees. The electric dipole polarizability, that is defined as the inverse energy-weighted sum rule of the E1 reduced transition strength, has been extracted as α{sub D} = 20.1 ±0.6 fm{sup 3}. A constraint band has been extracted in the plane of the symmetry energy (J) and its slope parameter (L) at the saturation density.

  20. Anomalies in the Nuclear Dissociation Cross Sections of {sup 208}Pb at 33 TeV

    SciTech Connect

    Datz, S.; Beene, J.R.; Krause, H.F.; Vane, C.R.; Grafstroem, P.; Schuch, R.H.

    1997-11-01

    We have measured total nuclear disintegration cross sections for {sup 208}Pb ions at 33TeV (160-GeV A) colliding with C, Si, Cu, Sn, and Pb. Using well established theory, we calculate the nuclear electromagnetic, electron electromagnetic, and the hadronic contributions and find that their sum underestimates the measured cross sections. An additive correction term linear in target Z{sub T} (i.e., 120Z{sub T} mb ) is necessary to bring agreement between theory and experiment. The source of this additional term is unknown. {copyright} {ital 1997} {ital The American Physical Society}

  1. Early Archean crustal evolution of the Jack Hills Zircon source terrane inferred from Lu-Hf, 207Pb/ 206Pb, and δ 18O systematics of Jack Hills zircons

    NASA Astrophysics Data System (ADS)

    Bell, Elizabeth A.; Harrison, T. Mark; McCulloch, Malcolm T.; Young, Edward D.

    2011-09-01

    Several lines of isotopic evidence - the most direct of which is from Hadean Jack Hills zircons - suggest a very early history of crust formation on Earth that began by about 4.5 Ga. To constrain both the fate of the reservoir for this crust and the nature of crustal evolution in the sediment source region of the Jack Hills, Western Australia, during the early Archean, we report here initial 176Hf/ 177Hf ratios and δ 18O systematics for <4 Ga Jack Hills zircons. In contrast to the significant number of Hadean zircons which contain highly unradiogenic 176Hf/ 177Hf requiring a near-zero Lu/Hf reservoir to have separated from the Earth's mantle by 4.5 Ga, Jack Hills zircons younger than ca. 3.6 Ga are more radiogenic than -13ɛ (CHUR) at 3.4 Ga in contrast to projected values at 3.4 Ga of -20ɛ for the unradiogenic Hadean reservoir indicating that some later juvenile addition to the crust is required to explain the more radiogenic younger zircons. The shift in the Lu-Hf systematics together with a narrow range of mostly mantle-like δ 18O values among the <3.6 Ga zircons (in contrast to the spread towards sedimentary δ 18O among Hadean samples) suggests a period of transition between 3.6 and 4 Ga in which the magmatic setting of zircon formation changed and the highly unradiogenic low Lu/Hf Hadean crust ceased to be available for intracrustal reworking. Constraining the nature of this transition provides important insights into the processes of crustal reworking and recycling of the Earth's Hadean crust as well as early Archean crustal evolution.

  2. Investigation of off-site airborne transport of lead from a superfund removal action site using lead isotope ratios and concentrations

    USGS Publications Warehouse

    Pribil, Michael J.; Maddaloni, Mark A.; Staiger, Kimberly; Wilson, Eric; Magriples, Nick; Ali, Mustafa; Santella, Dennis

    2014-01-01

    Lead (Pb) concentration and Pb isotopic composition of surface and subsurface soil samples were used to investigate the potential for off-site air transport of Pb from a former white Pb processing facility to neighboring residential homes in a six block area on Staten Island, NY. Surface and subsurface soil samples collected on the Jewett White Pb site were found to range from 1.122 to 1.138 for 206Pb/207Pb and 2.393 to 2.411 for 208Pb/207Pb. The off-site surface soil samples collected from residential backyards, train trestle, near site grass patches and background areas varied from 1.144 to 1.196 for 206Pb/207Pb and 2.427 to 2.464 for 208Pb/207Pb. Two soil samples collected along Richmond Terrace, where Jewett site soils accumulated after major rain events, varied from 1.136 to 1.147 for 206Pb/207Pb and 2.407 to 2.419 for 208Pb/207Pb. Lead concentration for on-site surface soil samples ranged from 450 to 8000 ug/g, on-site subsurface soil samples ranged from 90,000 to 240,000 ug/g and off-site samples varied from 380 to 3500 ug/g. Lead concentration and isotopic composition for the Staten Island off-site samples were similar to previously published data for other northeastern US cities and reflect re-suspension and re-mobilization of local accumulated Pb. The considerable differences in both the Pb isotopic composition and Pb concentration of on-site and off-site samples resulted in the ability to geochemically trace the transport of particulate Pb. Data in this study indicate minimal off-site surface transport of Pb from the Jewett site into the neighboring residential area.

  3. An odyssey of environmental pollution: the rise, fall and remobilization of industrial lead in Australia

    NASA Astrophysics Data System (ADS)

    Taylor, M. P.; Kristensen, L.; Liqin, W.; Harvey, P. J.; Dong, C.; Rouillon, M.

    2015-12-01

    The use of lead in automobile gasoline resulted in more than 240,000 tonnes of lead being emitted to the Australian environment over its 70-year period of use starting in 1932. The consequences of the emissions and subsequent depositions have resulted in marked contamination of urban and peri-urban aerosols, soils, plants and humans. This paper charts these effects and examines the extent of recovery from one of the most pervasive and persistent environmental pollutants. Lead isotopic composition of Adelaide and Sydney aerosol filters show that air lead composition shifts from values that approximate Broken Hill type ores, the predominant lead source used in gasoline (1.04 206Pb/207Pb and 2.31 208Pb/207Pb), towards ratios that more closely match local uncontaminated soil and bedrock values (Adelaide ~1.19 206Pb/207Pb and ~2.50 208Pb/207Pb; Sydney ~1.15 206Pb/207Pb and 2.48 208Pb/207Pb). Proxy atmospheric measurements from historic wine, lichen and fungi samples extending over 120 years show how both concentration and composition values shifted in the middle to late 20th century to reflect petrol emissions and then recovered rapidly at the end of the century as leaded gasoline consumption declined. For example, lead in wine from South Australia fell from >100 μg/L in the 1960s and 1970s to < 5 μg/L in the 2010s due to the removal of the primary source of atmospheric lead - gasoline. However, measurement of contemporary surface soils, ash produced from wildfires and air filters demonstrate that the effect of depositions persists and industrial lead and other toxic metals (including arsenic, cadmium and nickel) are subject to frequent remobilization. Predicted increases in wildfires and the generation of lead, arsenic and cadmium toxic particulates warrants greater consideration of the risk for vulnerable populations and firefighters who are most exposed.

  4. Thallium dispersal and contamination in surface sediments from South China and its source identification.

    PubMed

    Liu, Juan; Wang, Jin; Chen, Yongheng; Shen, Chuan-Chou; Jiang, Xiuyang; Xie, Xiaofan; Chen, Diyun; Lippold, Holger; Wang, Chunlin

    2016-06-01

    Thallium (Tl) is a non-essential element in humans and it is considered to be highly toxic. In this study, the contents, sources, and dispersal of Tl were investigated in surface sediments from a riverine system (the western Pearl River Basin, China), whose catchment has been contaminated by mining and roasting of Tl-bearing pyrite ores. The isotopic composition of Pb and total contents of Tl and other relevant metals (Pb, Zn, Cd, Co, and Ni) were measured in the pyrite ores, mining and roasting wastes, and the river sediments. Widespread contamination of Tl was observed in the sediments across the river, with the highest concentration of Tl (17.3 mg/kg) measured 4 km downstream from the pyrite industrial site. Application of a modified Institute for Reference Materials and Measurement (IRMM) sequential extraction scheme in representative sediments unveiled that 60-90% of Tl and Pb were present in the residual fraction of the sediments. The sediments contained generally lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratios compared with the natural Pb isotope signature (1.2008 and 2.0766 for (206)Pb/(207)Pb and (208)Pb/(206)Pb, respectively). These results suggested that a significant fraction of non-indigenous Pb could be attributed to the mining and roasting activities of pyrite ores, with low (206)Pb/(207)Pb (1.1539) and high (208)Pb/(206)Pb (2.1263). Results also showed that approximately 6-88% of Tl contamination in the sediments originated from the pyrite mining and roasting activities. This study highlights that Pb isotopic compositions could be used for quantitatively fingerprinting the sources of Tl contamination in sediments. PMID:27038575

  5. Characteristics of lead geochemistry and the mobility of Pb isotopes in the system of pedogenic rock-pedosphere-irrigated riverwater-cereal-atmosphere from the Yangtze River delta region, China.

    PubMed

    Wang, Cheng; Wang, Jianhua; Yang, Zhongfang; Mao, Changping; Ji, Junfeng

    2013-11-01

    Knowledge of the characteristics of Pb and its isotopic transfer in different compartments is scant, especially for the mobility of Pb isotopes in the geochemical cycle. The present study characterizes differential Pb transport mechanism and the mobility of Pb isotopes in the pedogenic parent rock-pedosphere-irrigated riverwater-cereal-atmosphere system in the Yangtze River delta region, by determining Pb concentration and Pb isotopic ratios of pedogenic parent rocks, fluvial suspended particle matter, tillage soils, soil profiles, irrigated riverwater, fertilizer, Pb ore, cereal roots and grains. The results show that Pb isotopes in the geochemical cycle generally follow the equation of (208)Pb/(206)Pb=-1.157×(206)Pb/(207)Pb+3.46 (r(2)=0.941). However, Pb isotopes have different mobility in different environmental matrixes. Whereas in the pedosphere, the heavier Pb ((208)Pb) usually shows stronger mobility relative to the lighter Pb, and is more likely to transfer into soil exchangeable Pb fraction and carbonates phase. The lighter Pb shows stronger transfer ability from soil to cereal grain via root compared to the heavier Pb. However, the cereal grains have lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratios than root and tillage soil, similar to the airborne Pb and anthropogenic Pb, implying that a considerable amount of Pb in cereal grains comes from the atmosphere. The estimate model shows that 16.7-52.6% (average: 33.5%) of Pb in rice grain is the airborne Pb.

  6. A two century record of lead isotopes in high altitude Alpine snow and ice

    NASA Astrophysics Data System (ADS)

    Rosman, K. J. R.; Ly, C.; Van de Velde, K.; Boutron, C. F.

    2000-03-01

    A 140 m snow/ice core drilled at Mont Blanc, France, has been analysed for Pb isotopes, Pb and Ba concentrations. The 206Pb/ 207Pb ratio, which was measured by thermal ionisation mass spectrometry, decreased steadily from ˜1.18 about two centuries ago to ˜1.17 in 1960, then fell rapidly to ˜1.15 by 1968. Evidence of the Italian (Turin) isotopic lead experiment (IILE) was found in samples dated ˜1977 where the ratio dipped to 1.117. By the early 1990s it had returned to mid 1960s values. Large seasonal variations were found in Pb and Ba concentrations. Summer samples were associated with smooth changes in the 206Pb/ 207Pb ratio while larger fluctuations were encountered in winter which is consistent with a low altitude inversion near Mont Blanc in the winter and free transfer of pollutants from lower to higher altitudes at other times. A plot of 208Pb/ 207Pb versus 206Pb/ 207Pb ratios reveals three isotopic groupings, associated with the periods pre-1923, 1923-1968 and 1969-1991. In the first group, the isotopic composition is consistent with local mining, smelting and coal burning, while in the second, motor vehicle exhaust emissions dominate. In the third group, motor vehicle emissions also dominate but the Pb is even less radiogenic. During this period the IILE occurred and there was a reduction in the use of leaded gasoline in Europe. A comparison of the Mont Blanc and Summit (central Greenland) records shows they contain similar 206Pb/ 207Pb ratios between 1960 and 1968, although small differences in isotopic composition can be detected by also considering the 208Pb/ 207Pb ratio. However, after 1969 the two records diverge markedly, with the Greenland ratios being dominated by the highly radiogenic Mississippi valley-type Pb from the USA and with the Mont Blanc ratios moving to lower values particularly about the time of the IILE.

  7. Diversity of neutron star properties at the fixed neutron-skin thickness of 208Pb

    NASA Astrophysics Data System (ADS)

    Alam, N.; Sulaksono, A.; Agrawal, B. K.

    2015-07-01

    We study the diversities in the properties of the neutron stars arising due to the different choices for the cross coupling between various mesons, which governs the density dependence of the nuclear symmetry energy in the extended relativistic mean-field (RMF) model. For this purpose, we obtain two different families of the extended RMF model corresponding to different nonlinear cross-coupling terms in the isovector part of the effective Lagrangian density. The lowest-order contributions for the δ mesons are also included. The different models within the same family yield wide variation in the value of neutron-skin thickness in the 208Pb nucleus. These models are employed to compute the neutron-star properties such as core-crust transition density, radius and red shift at canonical mass ( 1.4 M⊙) , tidal polarizability parameter, and threshold mass required for the enhanced cooling through the direct Urca process. Most of the neutron-star properties considered are significantly different(10-40%) for the different families of models at a smaller neutron-skin thickness (˜0.15 fm ) in the 208Pb nucleus.

  8. Trace element and Pb isotope composition of plagioclase from dome samples from the 2004-2005 eruption of Mount St. Helens, Washington: Chapter 35 in A volcano rekindled: the renewed eruption of Mount St. Helens, 2004-2006

    USGS Publications Warehouse

    Kent, Adam J.R.; Rowe, Michael C.; Thornber, Carl R.; Pallister, John S.; Sherrod, David R.; Scott, William E.; Stauffer, Peter H.

    2008-01-01

    Plagioclase crystals from gabbronorite inclusions in three dacite samples have markedly different trace-element and Pbisotope compositions from those of plagioclase phenocrysts, despite having a similar range of anorthite contents. Inclusions show some systematic differences from each other but typically have higher Ti, Ba, LREE, and Pb and lower Sr and have lower 208Pb/206Pb and 207Pb/206Pb ratios than coexisting plagioclase phenocrysts. The compositions of plagioclase from inclusions cannot be related to phenocryst compositions by any reasonable petrologic model. From this we suggest that they are unlikely to represent magmatic cumulates or restite inclusions but instead are samples of mafic Tertiary basement from beneath the volcano.

  9. Influences upon the lead isotopic composition of organic and mineral horizons in soil profiles from the National Soil Inventory of Scotland (2007-09).

    PubMed

    Farmer, John G; Graham, Margaret C; Eades, Lorna J; Lilly, Allan; Bacon, Jeffrey R

    2016-02-15

    Some 644 individual soil horizons from 169 sites in Scotland were analyzed for Pb concentration and isotopic composition. There were three scenarios: (i) 36 sites where both top and bottom (i.e. lowest sampled) soil horizons were classified as organic in nature, (ii) 67 with an organic top but mineral bottom soil horizon, and (iii) 66 where both top and bottom soil horizons were mineral. Lead concentrations were greater in the top horizon relative to the bottom horizon in all but a few cases. The top horizon (206)Pb/(207)Pb ratio was lesser (outside analytical error) than the corresponding bottom horizon (206)Pb/(207)Pb ratio at (i) 64%, (ii) 94% and (iii) 73% of sites, and greater at only (i) 8%, (ii) 3% and (iii) 8% of sites. A plot of (208)Pb/(207)Pb vs. (208)Pb/(206)Pb ratios showed that the Pb in organic top (i, ii) and bottom (i) horizons was consistent with atmospherically deposited Pb of anthropogenic origin. The (206)Pb/(207)Pb ratio of the organic top horizon in (ii) was unrelated to the (206)Pb/(207)Pb ratio of the mineral bottom horizon as demonstrated by the geographical variation in the negative shift in the ratio, a result of differences in the mineral horizon values arising from the greater influence of radiogenic Pb in the north. In (iii), the lesser values of the (206)Pb/(207)Pb ratio for the mineral top horizon relative to the mineral bottom horizon were consistent with the presence of anthropogenic Pb, in addition to indigenous Pb, in the former. Mean anthropogenic Pb inventories of 1.5 and 4.5 g m(-2) were obtained for the northern and southern halves of Scotland, respectively, consistent with long-range atmospheric transport of anthropogenic Pb (mean (206)Pb/(207)Pb ratio~1.16). For cultivated agricultural soils (Ap), this corresponded to about half of the total Pb inventory in the top 30 cm of the soil column. PMID:26674702

  10. A Clean Measurement of the Neutron Skin of 208Pb Through Parity Violating Electron Scattering

    SciTech Connect

    Riad Suleiman

    2003-07-01

    The difference between the neutron radius Rn of a heavy nucleus and the proton radius Rp is believed to be on the order of several percent. This qualitative feature of nuclei, which is essentially a neutron skin, has proven to be elusive to pin down experimentally in a rigorous fashion. A new Jefferson Lab experiment will measure the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 208Pb. Since the Z-boson couples mainly to neutrons, this asymmetry provides a measure of the size of Rn that can be interpreted with as much confidence as the traditional electron scattering data. The projected experimental precision corresponds to a 1% determination of Rn, which will have a big impact on nuclear theory and its application to neutron rich matter such as neutron stars.

  11. Gamow-Teller and dipole strength in the 208Pb(n,p) reaction

    NASA Astrophysics Data System (ADS)

    Raywood, K. J.; Long, S. A.; Spicer, B. M.

    1997-02-01

    Earlier data on the 208Pb(n,p) 208Ti reaction at 198 MeV has been analysed using the multipole decomposition technique, and the contributions to the spectra from L = 0 and 1 transitions determined. The L = 0 cross section has been found to be smaller than values given by the calculations of MacFarlane [3] for Gamow-Teller transitions, using three different forms for the population of single particle states about the Fermi energy. Comparison is made with GT-strength values obtained from a more recent mean field calculation of these populations, and with an older nuclear structure calculation of properties of the lead nuclei. The L = 1 strength distribution is also reported.

  12. Light charged particles emitted in fission reactions induced by protons on 208Pb

    NASA Astrophysics Data System (ADS)

    Rodríguez-Sánchez, J. L.; Benlliure, J.; Paradela, C.; Ayyad, Y.; Casarejos, E.; Alvarez-Pol, H.; Audouin, L.; Bélier, G.; Boutoux, G.; Chatillon, A.; Cortina-Gil, D.; Gorbinet, T.; Heinz, A.; Kelić-Heil, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.; Pietras, B.; Ramos, D.; Rodríguez-Tajes, C.; Rossi, D. M.; Simon, H.; Taïeb, J.; Vargas, J.; Voss, B.

    2016-09-01

    Light charged particles emitted in proton-induced fission reactions on 208Pb have been measured at different kinetic energies: 370 A ,500 A , and 650 A MeV. The experiment was performed by the SOFIA Collaboration at the GSI facilities in Darmstadt (Germany). The inverse kinematics technique was combined with a setup especially designed to measure light charged particles in coincidence with fission fragments. This measurement allowed us, for the first time, to obtain correlations between the light charged particles emitted during the fission process and the charge distributions of the fission fragments. These correlations were compared with different model calculations to assess the ground-to-saddle dynamics. The results confirm that transient and dissipative effects are required for an accurate description of the fission observables.

  13. Excitation energies of particle-hole states in {sup 208}Pb and the surface delta interaction

    SciTech Connect

    Heusler, A.; Jolos, R. V.; Brentano, P. von

    2013-07-15

    The schematic shell model without residual interaction (SSM) assumes the same excitation energy for all spins in each particle-hole configuration multiplet. In {sup 208}Pb, more than forty states are known to contain almost the full strength of a single particle-hole configuration. The experimental excitation energy for a state with a certain spin differs from the energy predicted by the SSM by -0.2 to +0.6 MeV. The multiplet splitting is calculated with the surface delta interaction; it corresponds to the diagonal matrix element of the residual interaction in the SSM. For states containing more than 90% strength of a certain configuration and for the centroid of several completely observed configurations, the calculated multiplet splitting often approximates the experimental excitation energy within 30 keV. The strong mixing within some pairs of states containing the full strengths of two configurations is explained.

  14. Fluctuation properties of the strength function associated with the giant quadrupole resonance in {sup 208}Pb

    SciTech Connect

    Aiba, Hirokazu; Matsuo, Masayuki; Nishizaki, Shigeru; Suzuki, Toru

    2011-02-15

    We performed fluctuation analysis by means of the local scaling dimension for the strength function of the isoscalar (IS) giant quadrupole resonance (GQR) in {sup 208}Pb where the strength function is obtained by the shell model calculation including 1p1h and 2p2h configurations. It is found that at almost all energy scales, fluctuation of the strength function obeys the Gaussian orthogonal ensemble (GOE) random matrix theory limit. This is contrasted with the results for the GQR in {sup 40}Ca, where at the intermediate energy scale of about 1.7 MeV, a deviation from the GOE limit was detected. It is found that the physical origin for this different behavior of the local scaling dimension is ascribed to the difference in the properties of the damping process.

  15. Correlations between Pb isotopes and volatile elements in melt inclusions from Sao Miguel, Azores

    NASA Astrophysics Data System (ADS)

    Moreira, M. A.; Rose-Koga, E. F.; Koga, K. T.; Vlastelic, I.; Shimizu, N.; Whitehouse, M.

    2009-12-01

    Sao Miguel is the biggest eastern-most island of the Azores archipelago in the northern Atlantic and is known to have a very peculiar isotopic systematics including Sr, Nd and Pb. We studied 4 lavas of Sao Miguel, one is from the 1563 historical lava flow Queimado peak eruption, one is from Picos Volcanic zone and the two others are Pliocene ankaramites from the Nordest. The olivine phenocrysts of these samples have been documented for helium isotopes and show very radiogenic 3He/4He ratios (<6Ra). We analyzed 9 primitive olivine-hosted melt inclusions for both Pb isotopes and volatile element concentrations (H2O, CO2, F, S, and Cl). The Pb isotope ratios were measured by a multicollection SIMS 1280 (NMNH Stockholm, Sweden) and volatiles by a monocollection SIMS 1280 (WHOI, USA). The repeated 207Pb/206Pb measurements of the GOR132 glass standard (20 ppm Pb) yielded a 0.15% relative variation (1 sigma of the distribution). All the melt inclusions have 207Pb/206Pb (0.782 to 0.797) and 208Pb/206Pb (1.969 to 2.041) lower than MORB value (DMM: 0.857, 2.053), i.e., more radiogenic compositions. We found positive linear correlations between 207Pb/206Pb and CO2, F, S, and Cl. The correlations further improve when Pb isotope ratios are plotted against F/P2O5, and Cl/K2O. The Sao Miguel source is characterized by a mixing between a low 207Pb/206Pb and low 208Pb/206Pb in the Nordest coming from a long time residence of high (U+Th)/Pb recycled material, and a component with higher ratios, more similar to other islands from the central group. The low 3He/4He ratio measured on Nordest samples also suggests a high (U+Th)/3He in its source, which may be due to degassing presumably during an early stage of the recycling. The low 207Pb/206Pb with low volatiles samples could also be explain this early degassing. Samples with the highest 207Pb/206Pb are richer in volatile suggesting the presence of a volatile rich lithology beneath the Azores central group, which was also proposed by

  16. Nuclear deformation of {sup 20}Ne from {sup 20}Ne(105 MeV)+{sup 208}Pb scattering

    SciTech Connect

    Strojek, I.; Czarnacki, W.; Keeley, N.; Kisielinski, M.; Piasecki, E.; Rusek, K.; Kliczewski, S.; Siudak, R.; Kordiasz, A.; Trzcinska, A.; Koshchiy, E.; Kowalczyk, M.; Piorkowska, A.; Stuad, A.

    2010-04-26

    We have measured differential cross section for quasielastic scattering of {sup 20}Ne+{sup 208}Pb at a lab energy of 105 MeV. The data are analyzed by a rotational-model coupled-channels calculation including the 0{sup +} ground state, 2{sup +} and 4{sup +} states of {sup 20}Ne.

  17. Complete dipole response in {sup 208}Pb from high-resolution polarized proton scattering at 0 deg

    SciTech Connect

    Neumann-Cosel, P. von; Kalmykov, Y.; Poltoratska, I.; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Adachi, T.; Fujita, Y.; Matsubara, H.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Yosoi, M.; Bertulani, C. A.; Carter, J.; Fujita, H.; Dozono, M.; Fujita, K.; Hashimoto, H.; Hatanaka, K.

    2009-01-28

    The structure of electric and magnetic dipole modes in {sup 208}Pb is investigated in a high-resolution measurement of the (p-vector,p-vector') reaction under 0 deg. First results on the E1 strength in the region of the pygmy dipole resonance are reported.

  18. A lead isotopic study of the human bioaccessibility of lead in urban soils from Glasgow, Scotland.

    PubMed

    Farmer, John G; Broadway, Andrew; Cave, Mark R; Wragg, Joanna; Fordyce, Fiona M; Graham, Margaret C; Ngwenya, Bryne T; Bewley, Richard J F

    2011-11-01

    The human bioaccessibility of lead (Pb) in Pb-contaminated soils from the Glasgow area was determined by the Unified Bioaccessibility Research Group of Europe (BARGE) Method (UBM), an in vitro physiologically based extraction scheme that mimics the chemical environment of the human gastrointestinal system and contains both stomach and intestine compartments. For 27 soils ranging in total Pb concentration from 126 to 2160 mg kg(-1) (median 539 mg kg(-1)), bioaccessibility as determined by the 'stomach' simulation (pH ~1.5) was 46-1580 mg kg(-1), equivalent to 23-77% (mean 52%) of soil total Pb concentration. The corresponding bioaccessibility data for the 'stomach+intestine' simulation (pH ~6.3) were 6-623 mg kg(-1) and 2-42% (mean 22%) of soil Pb concentration. The soil (206)Pb/(207)Pb ratios ranged from 1.057 to 1.175. Three-isotope plots of (208)Pb/(206)Pb against (206)Pb/(207)Pb demonstrated that (206)Pb/(207)Pb ratios were intermediate between values for source end-member extremes of imported Australian Pb ore (1.04)--used in the manufacture of alkyl Pb compounds (1.06-1.10) formerly added to petrol--and indigenous Pb ores/coal (1.17-1.19). The (206)Pb/(207)Pb ratios of the UBM 'stomach' extracts were similar (<0.01 difference) to those of the soil for 26 of the 27 samples (r=0.993, p<0.001) and lower in 24 of them. A slight preference for lower (206)Pb/(207)Pb ratio was discernible in the UBM. However, the source of Pb appeared to be less important in determining the extent of UBM-bioaccessible Pb than the overall soil total Pb concentration and the soil phases with which the Pb was associated. The significant phases identified in a subset of samples were carbonates, manganese oxides, iron-aluminium oxyhydroxides and clays.

  19. Quaternary geochronology using the U-Th-Pb method

    SciTech Connect

    Getty, S.R.; DePaolo, D.J.

    1995-08-01

    We describe a method of uranium-thorium-lead (U-Th-Pb) isotopic age dating for Quaternary rocks. The approach uses an instrumental mass discrimination correction for lead isotope ratios, which allows small enrichments of radiogenic {sup 206}Pb and {sup 208}Pb to be detected at the level of 0.001%. Igneous rocks hosting minerals with a range in {sup 238}U/{sup 204}Pb values of 100 can be dated with uncertainties of approximately {+-}15-20 kyr. A Quarternary rhyolite dated at 1.19 Ma by K-Ar yields a {sup 238}U-{sup 206}Pb age of 1.03{+-}0.10 Ma. A Holocene dacite (9.5 ka) has uniform {sup 206}Pb/{sup 207}Pb to within {+-}0.0015% in groundmass phases, but 1 mm plagioclase phenocrysts have lower {sup 206}Pb/{sup 207}Pb by 0.105{+-}0.002% indicating contamination of the magma after plagioclase crystallization. High precision {sup 206}Pb/{sup 207}Pb ratios may be a useful new tool for petrogenetic studies.

  20. Evaporation residue cross-section in the decay of 254No* formed in 206Pb + 48Ca and its isotopic dependence using other Pb targets within the dynamical cluster-decay model

    NASA Astrophysics Data System (ADS)

    Niyti; Gupta, Raj K.; Hess, Peter Otto

    2015-06-01

    The dynamical cluster-decay model (DCM), with deformation and orientation effects included, is used to calculate the fusion evaporation residue cross-sections σxn for x = 1, 2, 3 and 4 neutrons emission in a fusion reaction 206Pb + 48Ca → 254No* at various 48Ca-beam energies Elab = 212.7- 242.5 MeV (equivalently, E* = 19.8- 43.9 MeV). Considering the higher multipole deformations up to hexadecapole deformation β4i and the sticking moment-of-inertia IS, the DCM with pocket formula for nuclear proximity potential is shown to give a good description of the measured individual light-particle (here neutrons) decay channels for configurations of "hot, compact" orientations θci, within one parameter fitting of the neck-length ΔR. A check on some of the variables involved in DCM shows that (i) spherical configurations give nearly the same result as above for deformed and oriented ones; (ii) the non-sticking moment-of-inertia INS gives unphysical results; and (iii) configurations of "cold, elongated" orientations do not fit the data at all. Furthermore, for the four different isotopes of 204,206,207,208Pb-based reactions, the dependence of, say, the 2n-emission yield σ2n on the isotopic composition of the compound nucleus is also studied within the DCM for "hot" fusion process. Of all the four Pb-isotopes and three excitation energies E* considered, at each E*, the ΔR is largest for compound system 256No*, followed by 255No*, 254No* and smallest for 252No*, which means to suggest that the neutrons emission occur earliest for 256No*, then for 255No*, 254No* and finally by 252No*, in complete agreement with experimental data according to which compound system 256No* has the highest cross-section and 252No* the lowest with 255No* and 254No* lying in between. This result is related to the double magicity of both the target (208Pb) and projectile (48Ca) nuclei, as well as to the experimentally known result of projectile with a larger number of neutrons (here the target

  1. Elastic neutron scattering at 96 MeV from 12 C and 208 Pb

    NASA Astrophysics Data System (ADS)

    Klug, J.; Blomgren, J.; Ataç, A.; Bergenwall, B.; Hildebrand, A.; Johansson, C.; Mermod, P.; Nilsson, L.; Pomp, S.; Tippawan, U.; Elmgren, K.; Olsson, N.; Jonsson, O.; Prokofiev, A. V.; Renberg, P.-U.; Nadel-Turonski, P.; Dangtip, S.; Phansuke, P.; Österlund, M.; Le Brun, C.; Lecolley, J. F.; Lecolley, F. R.; Louvel, M.; Marie-Noury, N.; Schweitzer, C.; Eudes, Ph.; Haddad, F.; Lebrun, C.; Koning, A. J.; Ledoux, X.

    2003-12-01

    A facility for detection of scattered neutrons in the energy interval 50 130 MeV , SCANDAL, has recently been installed at the 20 180 MeV neutron beam line of the The Svedberg Laboratory, Uppsala. Elastic neutron scattering from 12 C and 208 Pb has been studied at 96 MeV in the 10° 70° interval. The achieved energy resolution, 3.7 MeV , is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3% , is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions based on phenomenology or microscopic nuclear theory.

  2. Quantitative determination of lead in mixtures of lead(II) halidesusing solid-state 207pb nmr spectroscopy

    SciTech Connect

    Glatfelter, Alicia; Stephenson, Nicole; Bai, Shi; Dybowski,Cecil; Perry, Dale L.

    2006-11-01

    A multi-spectrum technique for facile, quantitativedetermination of lead in solid materials using solid-state 207Pb NMR thatavoids the major problem of uniform excitation across a wide spectralrange has been demonstrated. The method can be employed without chemicalseparation or other chemical manipulations and without any prior samplepreparation, resulting in a non-destructive analysis, and producingresults that are in agreement with gravimetric analyses of mixed samplesof the lead halides.

  3. Plumbotectonic aspects of polymetallic vein mineralization in Paleozoic sediments and Proterozoic basement of Moravia (Czech Republic)

    NASA Astrophysics Data System (ADS)

    Slobodník, Marek; Jacher-Śliwczyńska, Katarzyna; Taylor, Matthew C.; Schneider, Jens; Dolníček, Zdeněk

    2008-02-01

    A regional isotopic study of Pb and S in hydrothermal galenas and U-Pb and S in potential source rocks was carried out for part of Moravia, Czech Republic. Two major generations of veins, (syn-) Variscan and post-Variscan, are defined based on the Pb-isotope system together with structural constraints (local structures and regional trends). The Pb-isotopic compositions of galena plot in two distinct populations with outliers in 206Pb/204Pb-207Pb/204Pb space. Galena from veins hosted in greywackes provides a cluster with the lowest Pb-Pb ratios: 206Pb/204Pb = 18.15-18.27, 207Pb/204Pb = 15.59-15.61, 208Pb/204Pb = 38.11-38.23. Those hosted in both limestones and greywackes provide the second cluster: 206Pb/204Pb = 18.37-18.44, 207Pb/204Pb = 15.60-15.63, 208Pb/204Pb = 38.14-38.32. These clusters suggest model Pb ages as Early Carboniferous and Triassic-Jurassic, the latter associated with MVT-like deposits. Two samples from veins hosted in Proterozoic rocks lie outside the two clusters: in metagranitoid (206Pb/204Pb = 18.55, 207Pb/204Pb = 15.64, 208Pb/204Pb = 38.29) and in orthogneiss (206Pb/204Pb = 18.79, 207Pb/204Pb = 15.73, 208Pb/204Pb = 38.54). The results from these two samples suggest an interaction of mineralizing fluids with the radiogenic Pb-rich source (basement?). The values of δ34S suggest the Paleozoic host rocks (mostly -6.7 to +5.2‰ CDT) as the source of S for hydrothermal sulfides (mostly -4.8 to +2.5‰ CDT). U-Pb data and Pb isotope evolutionary curves indicate that Late Devonian and Early Carboniferous sediments, especially siliciclastics, are the general dominant contributor of Pb for galena mineralization developed in sedimentary rocks. Plumbotectonic mixing occurred, it is deduced, only between the lower and the upper crust (the latter involving Proterozoic basement containing heterogeneous radiogenic Pb), without any significant input from the mantle. It is concluded that in the Moravo-Silesian and Rhenohercynian zones (including proximal

  4. Measurement of the {sup 208}Pb({sup 52}Cr,n){sup 259}Sg excitation function

    SciTech Connect

    Folden III, C. M.; Dragojevic, I.; Garcia, M. A.; Gates, J. M.; Nelson, S. L.; Hoffman, D. C.; Nitsche, H.; Duellmann, Ch. E.; Sudowe, R.; Gregorich, K. E.; Eichler, R.

    2009-02-15

    The excitation function for the {sup 208}Pb({sup 52}Cr,n){sup 259}Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of 320{sub -100}{sup +110} pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from {sup 259}Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the {sup 208}Pb({sup 52}Cr,2n){sup 258}Sg reaction was obtained, and an improved {sup 258}Sg half-life of 2.6{sub -0.4}{sup +0.6} ms was calculated by combining all available experimental data.

  5. Hindrance of complete fusion in the {sup 8}Li+{sup 208}Pb system at above-barrier energies

    SciTech Connect

    Aguilera, E. F.; Martinez-Quiroz, E.; Rosales, P.; Kolata, J. J.; DeYoung, P. A.; Peaslee, G. F.; Mears, P.; Guess, C.; Becchetti, F. D.; Lupton, J. H.; Chen, Yu

    2009-10-15

    The {sup 211,212}At yields resulting from the interaction of the radioactive projectile {sup 8}Li with a {sup 208}Pb target have been measured at energies between 3 and 8.5 MeV above the Coulomb barrier. They are signatures for fusion of the whole charge but not necessarily the whole mass of the projectile, so they are included in a corresponding operational definition of complete fusion. Within this definition, a fusion suppression factor of 0.70{+-}0.02 (stat.) {+-}0.04 (syst.) is deduced from a comparison to a one-dimensional barrier-penetration-model calculation using parameters extrapolated from values for {sup 6,7}Li+{sup 209}Bi and {sup 9}Be+{sup 208}Pb taken from the literature. Possible incomplete fusion processes are discussed and the results are fitted with a phenomenological model assuming breakup prior to fusion followed by capture of a {sup 7}Li fragment.

  6. Tracing changes in atmospheric sources of lead contamination using lead isotopic compositions in Australian red wine.

    PubMed

    Kristensen, Louise Jane; Taylor, Mark Patrick; Evans, Andrew James

    2016-07-01

    Air quality data detailing changes to atmospheric composition from Australia's leaded petrol consumption is spatially and temporally limited. In order to address this data gap, wine was investigated as a potential proxy for atmospheric lead conditions. Wine spanning sixty years was collected from two wine regions proximal to the South Australian capital city, Adelaide, and analysed for lead concentration and lead and strontium isotopic composition for source apportionment. Maximum wine lead concentrations (328 μg/L) occur prior to the lead-in-air monitoring in South Australia in the later 1970s. Wine lead concentrations mirror available lead-in-air measurements and show a declining trend reflecting parallel reductions in leaded petrol emissions. Lead from petrol dominated the lead in wine ((206)Pb/(207)Pb: 1.086; (208)Pb/(207)Pb: 2.360) until the introduction of unleaded petrol, which resulted in a shift in the wine lead isotopic composition closer to vineyard soil ((206)Pb/(207)Pb: 1.137; (208)Pb/(207)Pb: 2.421). Current mining activities or vinification processes appear to have no impact with recent wine samples containing less than 4 μg/L of lead. This study demonstrates wine can be used to chronicle changes in environmental lead emissions and is an effective proxy for atmospherically sourced depositions of lead in the absence of air quality data.

  7. Identification of environmental lead sources and pathways in a mining and smelting town: Mount Isa, Australia.

    PubMed

    Mackay, A K; Taylor, M P; Munksgaard, N C; Hudson-Edwards, K A; Burn-Nunes, L

    2013-09-01

    Lead (Pb) concentrations and isotopic compositions from soils, dusts and aerosols from public land and residential lots adjacent to the copper and Pb mine and smelter at Mount Isa, Australia, were examined to understand the sources and risks of environmental Pb exposure. Urban soil samples contain elevated Pb concentrations (mean 1560 mg/kg), of which 45-85% of the Pb is bioaccessible. The Pb isotopic composition of surface soils (0-2 cm), aerosols and dusts ((206)Pb/(207)Pb, (208)Pb/(207)Pb range: 1.049, 2.322-1.069, 2.345) are dominated by Pb derived from the Mount Isa Pb-zinc ore bodies. Underlying soil horizons (10-20 cm) have distinctly different Pb isotopic compositions ((206)Pb/(207)Pb, (208)Pb/(207)Pb range: 1.093, 2.354-1.212, 2.495). Surface soil-, dust- and aerosol-Pb are derived predominantly from smelter emissions and fugitive mining sources and not from in situ weathered bedrock. Remediation strategies should target legacy and ongoing sources of environmental Pb to mitigate the problem of Pb exposure at Mount Isa. PMID:23770073

  8. Tracing changes in atmospheric sources of lead contamination using lead isotopic compositions in Australian red wine.

    PubMed

    Kristensen, Louise Jane; Taylor, Mark Patrick; Evans, Andrew James

    2016-07-01

    Air quality data detailing changes to atmospheric composition from Australia's leaded petrol consumption is spatially and temporally limited. In order to address this data gap, wine was investigated as a potential proxy for atmospheric lead conditions. Wine spanning sixty years was collected from two wine regions proximal to the South Australian capital city, Adelaide, and analysed for lead concentration and lead and strontium isotopic composition for source apportionment. Maximum wine lead concentrations (328 μg/L) occur prior to the lead-in-air monitoring in South Australia in the later 1970s. Wine lead concentrations mirror available lead-in-air measurements and show a declining trend reflecting parallel reductions in leaded petrol emissions. Lead from petrol dominated the lead in wine ((206)Pb/(207)Pb: 1.086; (208)Pb/(207)Pb: 2.360) until the introduction of unleaded petrol, which resulted in a shift in the wine lead isotopic composition closer to vineyard soil ((206)Pb/(207)Pb: 1.137; (208)Pb/(207)Pb: 2.421). Current mining activities or vinification processes appear to have no impact with recent wine samples containing less than 4 μg/L of lead. This study demonstrates wine can be used to chronicle changes in environmental lead emissions and is an effective proxy for atmospherically sourced depositions of lead in the absence of air quality data. PMID:27037773

  9. Identification of environmental lead sources and pathways in a mining and smelting town: Mount Isa, Australia.

    PubMed

    Mackay, A K; Taylor, M P; Munksgaard, N C; Hudson-Edwards, K A; Burn-Nunes, L

    2013-09-01

    Lead (Pb) concentrations and isotopic compositions from soils, dusts and aerosols from public land and residential lots adjacent to the copper and Pb mine and smelter at Mount Isa, Australia, were examined to understand the sources and risks of environmental Pb exposure. Urban soil samples contain elevated Pb concentrations (mean 1560 mg/kg), of which 45-85% of the Pb is bioaccessible. The Pb isotopic composition of surface soils (0-2 cm), aerosols and dusts ((206)Pb/(207)Pb, (208)Pb/(207)Pb range: 1.049, 2.322-1.069, 2.345) are dominated by Pb derived from the Mount Isa Pb-zinc ore bodies. Underlying soil horizons (10-20 cm) have distinctly different Pb isotopic compositions ((206)Pb/(207)Pb, (208)Pb/(207)Pb range: 1.093, 2.354-1.212, 2.495). Surface soil-, dust- and aerosol-Pb are derived predominantly from smelter emissions and fugitive mining sources and not from in situ weathered bedrock. Remediation strategies should target legacy and ongoing sources of environmental Pb to mitigate the problem of Pb exposure at Mount Isa.

  10. Total fission cross section of {sup 181}Ta and {sup 208}Pb induced by protons at relativistic energies

    SciTech Connect

    Ayyad, Y.; Benlliure, J.; Casarejos, E.; Schmidt, K. H.; Jurado, B.; Pol, H. A.; Ricciardi, M. V.; Pleskac, R.; Enqvist, T.; Rejmund, F.; Giot, L.; Henzl, V.; Lukic, S.; Ngoc, S. N.; Boudard, A.; Leray, S.; Kurtukian, T.; Schmitt, C.; Henzlova, D.; Paradela, C.; Bacquias, A.; Loureiro, D. P.; Foehr, V.; Tarrio, D.; Kezzar, K.

    2011-07-01

    Total fission cross section induced by protons in {sup 181}Ta and {sup 208}Pb at energies in the range of 300 to 1000 A MeV have been measured at GSI (Germany) using the inverse kinematics technique. A dedicated setup with high efficiency made it possible to determine these cross sections with high accuracy. The new data seed light in the controversial results obtained so far and contribute to the understanding of the fission process at high excitation energies. (authors)

  11. Experimental Cross Sections for Reactions of Heavy Ions and 208Pb, 209Bi, 238U, and 248Cm Targets

    SciTech Connect

    Patin, Joshua B.

    2002-05-24

    The study of the reactions between heavy ions and {sup 208}Pb, {sup 209}Bi, {sup 238}U, and {sup 248} Cm targets was performed to look at the differences between the cross sections of hot and cold fusion reactions. Experimental cross sections were compared with predictions from statistical computer codes to evaluate the effectiveness of the computer code in predicting production cross sections. Hot fusion reactions were studied with the MG system, catcher foil techniques and the Berkeley Gas-filled Separator (BGS). 3n- and 4n-exit channel production cross sections were obtained for the {sup 238}U({sup 18}O,xn){sup 256-x}Fm, {sup 238}U({sup 22}Ne,xn){sup 260-x}No, and {sup 248}Cm({sup 15}N,xn){sup 263-x}Lr reactions and are similar to previous experimental results. The experimental cross sections were accurately modeled by the predictions of the HIVAP code using the Reisdorf and Schaedel parameters and are consistent with the existing systematics of 4n exit channel reaction products. Cold fusion reactions were examined using the BGS. The {sup 208}Pb({sup 48}Ca,xn){sup 256-x}No, {sup 208}Pb({sup 50}Ti,xn){sup 258-x}Rf, {sup 208}Pb({sup 51}V,xn){sup 259-x}Db, {sup 209}Bi({sup 50}Ti,xn){sup 259-x}Db, and {sup 209}Bi({sup 51}V,xn){sup 260-x}Sg reactions were studied. The experimental production cross sections are in agreement with the results observed in previous experiments. It was necessary to slightly alter the Reisdorf and Schaedel parameters for use in the HIVAP code in order to more accurately model the experimental data. The cold fusion experimental results are in agreement with current 1n- and 2n-exit channel systematics.

  12. Isotopic ratio based source apportionment of children's blood lead around coking plant area.

    PubMed

    Cao, Suzhen; Duan, Xiaoli; Zhao, Xiuge; Wang, Beibei; Ma, Jin; Fan, Delong; Sun, Chengye; He, Bin; Wei, Fusheng; Jiang, Guibin

    2014-12-01

    Lead exposure in the environment is a major hazard affecting human health, particularly for children. The blood lead levels in the local children living around the largest coking area in China were measured, and the source of blood lead and the main pathways of lead exposure were investigated based on lead isotopic ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) in blood and in a variety of media, including food, airborne particulate matter, soil, dust and drinking water. The children's blood lead level was 5.25 (1.59 to 34.36 as range) μg dL(-1), lower than the threshold in the current criteria of China defined by the US Centers for Disease Control (10 μg dL(-1)). The isotopic ratios in the blood were 2.111±0.018 for (208)Pb/(206)Pb and 0.864±0.005 for (207)Pb/(206)Pb, similar to those of vegetables, wheat, drinking water, airborne particulate matter, but different from those of vehicle emission and soil/dust, suggesting that the formers were the main pathway of lead exposure among the children. The exposure pathway analysis based on the isotopic ratios and the human health risk assessment showed that dietary intake of food and drinking water contributed 93.67% of total exposed lead. The study further indicated that the coal used in the coking plant is the dominant pollution source of lead in children's blood.

  13. Age of the moon: an isotopic study of uranium-thorium-lead systematics of lunar samples.

    PubMed

    Tatsumoto, M; Rosholt, J N

    1970-01-30

    Concentrations of U, Th, and Pb in Apollo 11 samples studied are low (U. 0.16 to 0.87; Th, 0.53 to 3.4; Pb, 0.29 to 1.7, in ppm) but the extremely radiogenic lead in samples allows radiometric dating. The fine dust and the breccia have a concordant age of 4.66 billion years on the basis of (207)Pb/(206)Pb, (206)Pb/(238)U, (207)Pb/(235U), and(208)Pb/(232)Th ratios. This age is comparable with the age of meteorites and with the age generally accepted for the earth. Six crystalline and vesicular samples are distinctly younger than the dust and breccia. The (238)U/(235)U ratio is the same as that in earth rocks, and (234)U is in radioactive equilibrium with parent (238)U.

  14. A new method for stable lead isotope extraction from seawater.

    PubMed

    Zurbrick, Cheryl M; Gallon, Céline; Flegal, A Russell

    2013-10-24

    A new technique for stable lead (Pb) isotope extraction from seawater is established using Toyopearl AF-Chelate 650M(®) resin (Tosoh Bioscience LLC). This new method is advantageous because it is semi-automated and relatively fast; in addition it introduces a relatively low blank by minimizing the volume of chemicals used in the extraction. Subsequent analyses by HR ICP-MS have a good relative external precision (2σ) of 3.5‰ for (206)Pb/(207)Pb, while analyses by MC-ICP-MS have a better relative external precision of 0.6‰. However, Pb sample concentrations limit MC-ICP-MS analyses to (206)Pb, (207)Pb, and (208)Pb. The method was validated by processing the common Pb isotope reference material NIST SRM-981 and several GEOTRACES intercalibration samples, followed by analyses by HR ICP-MS, all of which showed good agreement with previously reported values.

  15. Age of the moon: An isotopic study of uranium-thorium-lead systematics of lunar samples

    USGS Publications Warehouse

    Tatsumoto, M.; Rosholt, J.N.

    1970-01-01

    Concentrations of U, Th, and Pb in Apollo 11 samples studied are low (U. 0.16 to 0.87; Th, 0.53 to 3.4; Pb, 0.29 to 1.7, in ppm) but the extremely radiogenic lead in samples allows radiometric dating. The fine dust and the breccia have a concordant age of 4.66 billion years on the basis of 207Pb/206Pb, 206Pb/238U, 207Pb/235U, and 208Pb/232Th ratios. This age is comparable with the age of meteorites and with the age generally accepted for the earth. Six crystalline and vesicular samples are distinctly younger than the dust and breccia. The 238U/235U ratio is the same as that in earth rocks, and 234U is in radioactive equilibrium with parent 238U.

  16. Weak charge form factor and radius of 208Pb through parity violation in electron scattering

    DOE PAGES

    Horowitz, C. J.; Ahmed, Z.; Jen, C. -M.; Rakhman, A.; Souder, P. A.; Dalton, M. M.; Liyanage, N.; Paschke, K. D.; Saenboonruang, K.; Silwal, R.; et al

    2012-03-26

    We use distorted wave electron scattering calculations to extract the weak charge form factor FW(more » $$\\bar{q}$$), the weak charge radius RW, and the point neutron radius Rn, of 208Pb from the PREX parity violating asymmetry measurement. The form factor is the Fourier transform of the weak charge density at the average momentum transfer $$\\bar{q}$$ = 0.475 fm-1. We find FW($$\\bar{q}$$) = 0.204 ± 0.028(exp) ± 0.001(model). We use the Helm model to infer the weak radius from FW($$\\bar{q}$$). We find RW = 5.826 ± 0.181(exp) ± 0.027(model) fm. Here the exp error includes PREX statistical and systematic errors, while the model error describes the uncertainty in RW from uncertainties in the surface thickness σ of the weak charge density. The weak radius is larger than the charge radius, implying a 'weak charge skin' where the surface region is relatively enriched in weak charges compared to (electromagnetic) charges. We extract the point neutron radius Rn = 5.751 ± 0.175 (exp) ± 0.026(model) ± 0.005(strange) fm, from RW. Here there is only a very small error (strange) from possible strange quark contributions. We find Rn to be slightly smaller than RW because of the nucleon's size. As a result, we find a neutron skin thickness of Rn-Rp = 0.302 ± 0.175 (exp) ± 0.026 (model) ± 0.005 (strange) fm, where Rp is the point proton radius.« less

  17. Isotopic source signatures for atmospheric lead: the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Bollhöfer, A.; Rosman, K. J. R.

    2000-10-01

    Aerosols collected between 1994 and 1999 at more than 70 different sites affecting the Southern Hemisphere have been measured for their 206Pb/ 207Pb, 208Pb/ 207Pb and 206Pb/ 204Pb ratios and Pb concentrations. Lower ratios are found at the southern tips of Africa, Australia and South America probably due to the supply of alkyllead from a common supplier such as Associated Octel. The ratios increase in a northerly direction probably due to a changing market share in alkyllead or an increasing industrial Pb contribution. The geographical variations in isotopic signatures made it possible to broadly characterize the different regions that influence the Southern Hemisphere. Brazil and Argentina exhibited 206Pb/ 207Pb, 208Pb/ 207Pb and 206Pb/ 204Pb ratios in aerosols of 1.141-1.184, 2.416-2.442 and 17.77-18.57, respectively. Mexican aerosols had values of 1.188-1.197, 2.452-2.463 and 18.46-18.73. Aerosols sampled in Chile had low ratios in the South of 1.063-1.094, 2.337-2.373 and 16.46-17.13 which increased in a northerly direction. Emissions from South Africa were characterized by ratios 1.067-1.090, 2.340-2.358 and 16.53-16.99. In 1994-1995 Australia and New Zealand had ratios of 1.060-1.193, 2.324-2.445 and 16.08-18.54. In 1997 however, the range was narrower: 1.072-1.112, 2.342-2.398 and 16.55-17.36, respectively. These isotopic signatures are potentially useful for tracing sources of pollution and the movement of air-masses on a global scale.

  18. A comparison of the isotopic composition of lead in rainwater, surface vegetation and tree bark at the long-term monitoring site, Glensaugh, Scotland, in 2007.

    PubMed

    Farmer, John G; Eades, Lorna J; Graham, Margaret C; Cloy, Joanna M; Bacon, Jeffrey R

    2010-08-01

    The lead concentrations and isotopic ratios (206Pb/207Pb, 208Pb/206Pb, 208Pb/207Pb) of 31 rainwater (September 2006-December 2007) and 11 surface vegetation (moss, lichen, heather) samples (October 2007) from the rural upland catchment of Glensaugh in northeast Scotland and of nine bark samples (October 2007) from trees, predominantly Scots pine, in or near Glensaugh were determined. The mean 206Pb/207Pb ratios for rainwater in 2006 and 2007 were similar to those previously determined for 2000 to 2003 at Glensaugh, yielding an average mean annual value of 1.151+/-0.005 (+/-1 SD) for the period from 2000, when an outright ban on leaded petrol came into force in the UK, to 2007. The mean 206Pb/207Pb ratio (1.146+/-0.004; n=7) for surface vegetation near the top (430-450 m) of the catchment was not significantly different (Student's t test) from that of rainwater (1.148+/-0.017; n=24) collected over the 12-month period prior to vegetation sampling, but both were significantly different, at the 0.1% (i.e. p<0.001) and 1% (p<0.01) level, respectively, from the corresponding mean value (1.134+/-0.006; n=9) for the outermost layer of tree bark. When considered in conjunction with similar direct evidence for 2002 and indirect evidence (e.g. grass, atmospheric particulates, dated peat) for recent decades in the Glensaugh area, these findings confirm that the lead isotopic composition of surface vegetation, including that of suitably located moss, reflects that of the atmosphere while that of the outermost layer of Scots pine bark is affected by non-contemporaneous lead. The nature and relative extent of the different contributory sources of lead to the current UK atmosphere in the era of unleaded petrol, however, are presently not well characterised on the basis of lead isotopic measurements.

  19. Anthropogenic lead concentrations and sources in Baltic Sea sediments based on lead isotopic composition.

    PubMed

    Zaborska, Agata

    2014-08-15

    The Gulf of Gdańsk is influenced by heavy metals of anthropogenic origin. In this study, temporal concentration changes of Pb, Zn, Cd, and Cu were studied in six, 50 cm long sediment cores. The main aim of the study was to concentrate on the history of Pb fluxes and Pb isotopic composition ((206)Pb/(207)Pb and (208)Pb/(206)Pb) to trace Pb sources. The lowest Pb concentrations (19 μg g(-1)) were measured in sediments deposited circa 1860, while the highest Pb concentrations (63-147 μg g(-1)) were measured in sediments deposited between 1960s and 70s. Pre-industrial Pb fluxes were 7 Pb m(2)year(-1), while after WWII they reached 199 Pb m(2)year(-1). Highest (206)Pb/(207)Pb ratios (∼1.22) were measured in the oldest sediment layers, and the lowest (206)Pb/(207)Pb ratios (∼1.165) were measured in the sediments deposited in 1970s-90s. During the period of highest Pb contamination, the anthropogenic Pb fraction reached up to 93%. A general discussion of the Pb sources, emissions, and loads for Poland is included.

  20. Dendrochemical record of historical lead contamination sources, Wells G&H Superfund site, Woburn, Massachusetts.

    PubMed

    Burnett, Aaron; Kurtz, Andrew C; Brabander, Daniel; Shailer, Mark

    2007-01-01

    Laser-ablation inductively coupled-plasma mass-spectrometry analysis of red oak (Quercus rubra) from a well documented heavy metal contaminated United States Environmental Protection Agency superfund site in Woburn, Massachusetts reveals decade-long trends in Pb contaminant sources. Lead isotope ratios (207Pb/206Pb and 208Pb/206Pb) in tree rings plot along a linear trend bracketed by several local and regional contamination sources. Statistically significant interannual variations in 207Pb/206Pb suggest that atmospheric Pb is rapidly incorporated into wood, with minimal mobility subsequent to deposition in annual growth rings. We interpret the decadal trends in our record as a changing mixture of local pollution sources and gasoline-derived Pb. Between 1940 and 1970, Pb was predominantly derived from remobilization of local industrial Pb sources. An abrupt shift in 207Pb/206Pb may indicate that local Pb sources were overwhelmed by gasoline-derived Pb during the peak of leaded gasoline emissions in the late 1960s and early 1970s.

  1. Study of the γ decay of high-lying states in 208Pb via inelastic scattering of 17O ions

    NASA Astrophysics Data System (ADS)

    Crespi, F. C. L.; Kmiecik, M.; Bracco, A.; Leoni, S.; Maj, A.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Camera, F.; Ceruti, S.; Giaz, A.; Million, B.; Morales, A. I.; Nicolini, R.; Pellegri, L.; Riboldi, S.; Vandone, V.; Wieland, O.; Bednarczyk, P.; Ciemala, M.; Grebosz, J.; Krzysiek, M.; Mazurek, K.; Zieblinski, M.; Bazzacco, D.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Calore, E.; De Angelis, G.; Farnea, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Isocrate, R.; Lenzi, S.; Lunardi, S.; Mengoni, D.; Michelagnoli, C.; Molini, P.; Napoli, D. R.; Recchia, F.; Sahin, E.; Siebeck, B.; Siem, S.; Ur, C.; Valiente Dobon, J. J.

    2014-03-01

    A measurement of the high-lying states in 208Pb has been made using 17O beams at 20 MeV/u. The gamma decay following inelastic excitation was measured with the detector system AGATA Demonstrator based on segmented HPGe detectors, coupled to an array of large volume LaBr3:Ce scintillators and to an array of Si detectors. Preliminary results in comparison with (γ,γ') data, for states in the 5-8 MeV energy interval, are presented.

  2. Nuclear spectroscopy study of the isotopes populated via multinucleon transfer in the 90Zr + 208Pb reaction

    SciTech Connect

    Ur, C. A.; Corradi, L.; Stefanini, A. M.; Behera, B. R.; Fioretto, E.; Gadea, A.; Latina, A.; Szilner, S.; Beghini, S.; Farnea, E.; Montagnoli, G.; Scarlassara, F.; Haas, F.; Pollarolo, G.

    2006-08-14

    The present work takes advantage of the multinucleon transfer mechanism between heavy reaction partners to study the population pattern of excited nuclear states in near spherical Zirconium isotopes following the 90Zr + 208Pb reaction at an energy closed to the Coulomb barrier. Both the projectile and the target are well known closed shell nuclei offering an optimum situation for clean experimental and theoretical conditions. Total kinetic energy loss (TKEL) distributions were compared with calculations performed with the GRAZING code. The ability to use the TKEL as a selection tool for the states at different excitation energies was shown.

  3. Response function of the magnetic spectrometer PRISMA for the multinucleon transfer reaction {sup 40}Ar+{sup 208}Pb

    SciTech Connect

    Mijatovic, T.; Szilner, S.; Corradi, L.; Courtin, S.; Farnea, E.; Fioretto, E.; Gadea, A.; Goasduff, A.; Haas, F.; Jelavic-Malenica, D.; Lunardi, S.; Mengoni, D.; Montagnoli, G.; Montanari, D.; Pollarolo, G.; Recchia, F.; Sahin, E.; Scarlassara, F.; Soic, N.; Stefanini, A. M.; and others

    2012-10-20

    Multinucleon transfer reaction {sup 40}Ar+{sup 208}Pb has been investigated with the PRISMA-CLARA experimental setup in LNL, INFN, Italy. The experimental differential cross sections have been obtained for different transfer channels by measuring more than {Delta}{theta}{sub lab} = 20 Degree-Sign covered by three angular settings of PRISMA. Results have been compared with the semiclassical calculation GRAZING. Since the understanding of the reaction mechanism depends strongly on the determination of absolute cross section, effect of transport of ions through PRISMA has been studied via a Monte Carlo simulation code.

  4. Pionic fusion near threshold using the /sup 208/Pb(/sup 3/He,. pi. /sup -/)/sup 211/At reaction

    SciTech Connect

    Ward, T.E.

    1987-12-01

    The coherent production of pions in the /sup 208/Pb(/sup 3/He,..pi../sup -/)/sup 211/At reaction was measured radiochemically using activation techniques near the physical pion threshold at energies of 158--270 MeV. Above threshold, the total cross sections were measured in the 1--10 nb range. A theoretical fit of the summed total cross section into all particle bound states was made using the two-nucleon model of Dillig with appropriate two-body scaling of the momentum transfer.

  5. Levels and source apportionment of children's lead exposure: could urinary lead be used to identify the levels and sources of children's lead pollution?

    PubMed

    Cao, Suzhen; Duan, Xiaoli; Zhao, Xiuge; Wang, Beibei; Ma, Jin; Fan, Delong; Sun, Chengye; He, Bin; Wei, Fusheng; Jiang, Guibin

    2015-04-01

    As a highly toxic heavy metal, the pollution and exposure risks of lead are of widespread concern for human health. However, the collection of blood samples for use as an indicator of lead pollution is not always feasible in most cohort or longitudinal studies, especially those involving children health. To evaluate the potential use of urinary lead as an indicator of exposure levels and source apportionment, accompanying with environmental media samples, lead concentrations and isotopic measurements (expressed as (207)Pb/(206)Pb, (208)Pb/(206)Pb and (204)Pb/(206)Pb) were investigated and compared between blood and urine from children living in the vicinities of a typical coking plant and lead-acid battery factory. The results showed urinary lead might not be a preferable proxy for estimating blood lead levels. Fortunately, urinary lead isotopic measurements could be used as an alternative for identifying the sources of children's lead exposure, which coincided well with the blood lead isotope ratio analysis.

  6. Levels and source apportionment of children's lead exposure: could urinary lead be used to identify the levels and sources of children's lead pollution?

    PubMed

    Cao, Suzhen; Duan, Xiaoli; Zhao, Xiuge; Wang, Beibei; Ma, Jin; Fan, Delong; Sun, Chengye; He, Bin; Wei, Fusheng; Jiang, Guibin

    2015-04-01

    As a highly toxic heavy metal, the pollution and exposure risks of lead are of widespread concern for human health. However, the collection of blood samples for use as an indicator of lead pollution is not always feasible in most cohort or longitudinal studies, especially those involving children health. To evaluate the potential use of urinary lead as an indicator of exposure levels and source apportionment, accompanying with environmental media samples, lead concentrations and isotopic measurements (expressed as (207)Pb/(206)Pb, (208)Pb/(206)Pb and (204)Pb/(206)Pb) were investigated and compared between blood and urine from children living in the vicinities of a typical coking plant and lead-acid battery factory. The results showed urinary lead might not be a preferable proxy for estimating blood lead levels. Fortunately, urinary lead isotopic measurements could be used as an alternative for identifying the sources of children's lead exposure, which coincided well with the blood lead isotope ratio analysis. PMID:25617855

  7. Lead shot contribution to blood lead of First Nations people: the use of lead isotopes to identify the source of exposure.

    PubMed

    Tsuji, Leonard J S; Wainman, Bruce C; Martin, Ian D; Sutherland, Celine; Weber, Jean-Philippe; Dumas, Pierre; Nieboer, Evert

    2008-11-01

    Although lead isotope ratios have been used to identify lead ammunition (lead shotshell pellets and bullets) as a source of exposure for First Nations people of Canada, the actual source of lead exposure needs to be further clarified. Whole blood samples for First Nations people of Ontario, Canada, were collected from participants prior to the traditional spring harvest of water birds, as well as post-harvest. Blood-lead levels and stable lead isotope ratios prior to, and after the harvest were determined by ICP-MS. Data were analyzed by paired t-tests and Wilcoxon Signed-Ranks tests. All participants consumed water birds harvested with lead shotshell during the period of study. For the group excluding six males who were potentially exposed to other sources of lead (as revealed through a questionnaire), paired t-tests and Wilcoxon Signed-Ranks tests showed consistent results: significant (p<0.05) increases in blood-lead concentrations and blood levels of (206)Pb/(204)Pb and (206)Pb/(207)Pb towards the mean values we previously reported for lead shotshell pellets; and a significant decrease in (208)Pb/(206)Pb values towards the mean for lead shotshell pellets. However, when we categorized the group further into a group that did not use firearms and did not eat any other traditional foods harvested with lead ammunition other than waterfowl, our predictions for (206)Pb/(204)Pb, (206)Pb/(207)Pb and (208)Pb/(206)Pb hold true, but there was not a significant increase in blood-lead level after the hunt. It appears that the activity of hunting (i.e., use of a shotgun) was also an important route of lead exposure. The banning of lead shotshell for all game hunting would eliminate a source of environmental lead for all people who use firearms and/or eat wild game.

  8. Metal enrichment and lead isotope analysis for source apportionment in the urban dust and rural surface soil.

    PubMed

    Yu, Yang; Li, Yingxia; Li, Ben; Shen, Zhenyao; Stenstrom, Michael K

    2016-09-01

    To understand the metal accumulation in the environment and identify its sources, 29 different metal contents and lead (Pb) isotope ratios were determined for 40 urban dust samples, 36 surface soil samples, and one river sediment sample collected in the municipality of Beijing, China. Results showed that cadmium, copper (Cu), mercury, Pb, antimony (Sb), and zinc demonstrated to be the typical urban contaminants and mostly influenced by the adjacent human activities with higher content to background ratios and SD values. Among the 29 metal elements investigated, Cu and Sb were found to be the most distinct elements that were highly affected by the developing level and congestion status of the cities with much higher contents in dust in more developed and congested cities. There was a relatively wider range of Pb isotope ratios of country surface soil than those of urban dust. The results of source identification based on Pb isotope ratios showed that coal combustion was the first largest Pb source and vehicle exhaust was the second largest source. The sum of them accounted for 74.6% mass proportion of overall Pb pollution on average. The surface soil sample collected at an iron mine had the highest (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios indicating ore had much higher ratios than other sources. The fine particle subsamples had higher (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios than the coarse particle subsamples indicating more anthropogenic sources of coal combustion and vehicle exhaust for fine particles and more background influence for coarse particles. These results help with pinpointing the major Pb sources and applying suitable measures for the target sources. PMID:27376990

  9. Metal enrichment and lead isotope analysis for source apportionment in the urban dust and rural surface soil.

    PubMed

    Yu, Yang; Li, Yingxia; Li, Ben; Shen, Zhenyao; Stenstrom, Michael K

    2016-09-01

    To understand the metal accumulation in the environment and identify its sources, 29 different metal contents and lead (Pb) isotope ratios were determined for 40 urban dust samples, 36 surface soil samples, and one river sediment sample collected in the municipality of Beijing, China. Results showed that cadmium, copper (Cu), mercury, Pb, antimony (Sb), and zinc demonstrated to be the typical urban contaminants and mostly influenced by the adjacent human activities with higher content to background ratios and SD values. Among the 29 metal elements investigated, Cu and Sb were found to be the most distinct elements that were highly affected by the developing level and congestion status of the cities with much higher contents in dust in more developed and congested cities. There was a relatively wider range of Pb isotope ratios of country surface soil than those of urban dust. The results of source identification based on Pb isotope ratios showed that coal combustion was the first largest Pb source and vehicle exhaust was the second largest source. The sum of them accounted for 74.6% mass proportion of overall Pb pollution on average. The surface soil sample collected at an iron mine had the highest (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios indicating ore had much higher ratios than other sources. The fine particle subsamples had higher (204)Pb/(206)Pb, (207)Pb/(206)Pb, and (208)Pb/(206)Pb ratios than the coarse particle subsamples indicating more anthropogenic sources of coal combustion and vehicle exhaust for fine particles and more background influence for coarse particles. These results help with pinpointing the major Pb sources and applying suitable measures for the target sources.

  10. 207,208Pb(n,xnγ) reactions for neutron energies from 3 to 200 MeV

    NASA Astrophysics Data System (ADS)

    Vonach, H.; Pavlik, A.; Chadwick, M. B.; Haight, R. C.; Nelson, R. O.; Wender, S. A.; Young, P. G.

    1994-10-01

    High-resolution γ-ray spectra from the interaction of neutrons in the energy range from 3 to 200 MeV with 207,208Pb were measured with the white neutron source at the weapons neutron research (WNR) facility at Los Alamos National Laboratory. From these data, excitation functions for prominent γ transitions in 200,202,204,206,207,208Pb were derived from threshold to 200 MeV incident neutron energy. These γ-production cross sections reflect the excitation cross sections for the respective residual nuclei. The results are compared with the predictions of nuclear reaction calculations based on the exciton model for precompound emission, the Hauser-Feshbach theory for compound nucleus decay, and coupled channels calculations to account for direct excitation of collective levels. Good agreement was obtained over the entire energy range covered in the experiment with reasonable model parameters. The results of this work clearly demonstrate that multiple preequilibrium emission has to be taken into account above about 40 MeV, and that the level density model of Ignatyuk, which accounts for the gradual disappearance of shell effects with increasing excitation energy, should be used instead of the Gilbert-Cameron and backshifted Fermi-gas models if excitation energies exceed about 30 MeV. No indication for a reduction of the nuclear moment of inertia below the rigid body value was found.

  11. Lead isotopes and lead shot ingestion in the globally threatened marbled teal (Marmaronetta angustirostris) and white-headed duck (Oxyura leucocephala).

    PubMed

    Svanberg, Fredrik; Mateo, Rafael; Hillström, Lars; Green, Andy J; Taggart, Mark A; Raab, Andrea; Meharg, Andy A

    2006-11-01

    Lead isotope ratios ((206)Pb/(207)Pb and (208)Pb/(207)Pb) and concentrations in the livers and bones of marbled teal and white-headed duck found dead or moribund were determined in order to establish the main lead source in these waterfowl species. Lead concentrations in bone (dry weight) and liver (wet weight) were found to be very high in many of the white-headed ducks (bone: geometric mean=88.9 ppm, maximum=419 ppm; liver: geometric mean=16.8 ppm, maximum=57.0 ppm). Some of the marbled teal had high lead levels in the bones but liver lead levels were all low (bone: geometric mean=6.13 ppm, maximum=112 ppm; liver: geometric mean=0.581 ppm, maximum=4.77 ppm). Ingested lead shot were found in 71% of the white-headed duck and 20% of the marbled teal. The (206)Pb/(207)Pb ratio in livers and bones of white-headed ducks and marbled teals showed no significant differences compared to the ratios obtained from lead shot. The (206)Pb/(207)Pb ratio in bones of marbled teal ducklings with the highest lead concentrations tended to resemble the ratios of lead shot, which supports our hypothesis that the lead was derived from the hens. We also found that the lead ratios of lead shot and lead ratios described for soils in the area overlapped, but also that the isotopic ratio (206)Pb/(207)Pb in lead shot used in Spain has a narrow range compared with those used in North America. The principal source of lead in many of these birds was, however, most likely lead shot, as supported by the similar isotopic ratios, high lead concentrations in tissues and evidence of ingested shot.

  12. Radial distribution of lead and lead isotopes in stem wood of Norway spruce: A reliable archive of pollution trends in Central Europe

    NASA Astrophysics Data System (ADS)

    Novak, Martin; Mikova, Jitka; Krachler, Michael; Kosler, Jan; Erbanova, Lucie; Prechova, Eva; Jackova, Iva; Fottova, Daniela

    2010-08-01

    Annual growth rings of a common hardwood species, Picea abies L., were investigated as a potential archive of past atmospheric Pb pollution. Wide distribution of trees in terrestrial settings and straightforward chronology are two advantages of this potential geochemical archive, but several processes described in the literature may obscure the trends in past Pb deposition. These confounding factors include, e.g., radial post-depositional mobility of Pb in xylem, and ecosystem acidification leading to higher bioavailability of Pb. One- to five-year annual wood increments were analyzed for Pb concentrations and 206Pb/ 207Pb ratios at Jezeri (JEZ), Uhlirska (UHL) and Na Lizu (LIZ), three sites in the Czech Republic, differing in atmospheric Pb loads. Three to four trees per site were included in the study. Distinct Pb concentration maxima between 1960 and 1990 at the two heavily polluted sites (JEZ and UHL) coincided with historical Pb emissions known from inventories of industrial production. No Pb concentration maxima were found at one site, LIZ, situated in a national park 150 km from major pollution sources. Spruce tree rings from JEZ, located just 5 km from coal-burning power stations, contained a large proportion of coal-derived Pb (a high- 206Pb/ 207Pb ratio of 1.19). A coal-related maximum in 206Pb/ 207Pb in JEZ tree rings was found using two different analytical techniques, laser-ablation multi-collector ICP MS, and single-collector sector-field ICP MS. In a three-isotope graph ( 206Pb/ 207Pb vs. 208Pb/ 207Pb), tree-ring data plotted into the field of ombrotrophic (i.e., rain-fed) peat bogs, suggesting negligible contribution of bedrock-derived Pb in the xylem. We concluded that none of the potential confounding factors played a major role at our sites. Annual growth rings of P. abies in Central Europe faithfully recorded historical changes in atmospheric Pb depositions.

  13. Solid-state 207pb nmr studies of lead-group 16 and mixedtransition-metal-lead-group 16 element-containing materials

    SciTech Connect

    Van Bramer, S.E.; Glatfelter, A.; Bai, S.; Dybowksi, C.; GNeue,G.; Perry, D.L.

    2005-08-26

    207Pb solid-state NMR studies have been conducted on binarylead-group 16 and mixed transition-metal/lead group 16 materials,correlating the NMR chemical shifts of the materials with theirstructures. The experimental results show that the 207Pb chemical shiftsare strongly influenced by the local electronic structure. Data arereported for lead selenide, lead selenate, calcium plumbate, strontiumplumbite, barium plumbite, lead borate, lead zirconate, lead tungstate,lead meta-tantalate, lead niobate, lead molybdate, lead meta-vanadate,lead sulfite, and lead sulfate.

  14. Comparison of the concentrations of metal elements and isotopes of lead found in rice and rice bran.

    PubMed

    Dai, Shouhui; Yang, Hui; Yang, Lan; Wang, Fuhua; Du, Ruiying; Wen, Dian

    2014-08-01

    Very few studies have investigated the difference in the distribution of metal elements between rice and rice bran samples. In this study, the concentrations of 27 metal elements (Li, Be, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Ag, Cd, Cs, Ba, Tl, Pb, and U) in 56 polished rice and their corresponding bran samples were determined. A significant difference in concentrations of all elements except Ag and Cd was found between rice and bran (P < 0.05), with bran/rice ratios of 1.21 to 36.3. High concentrations of metal elements, especially that of the heavy metal Cr, in bran samples present a potential safety issue for bran products, such as food and feed containing bran. Pb isotope ((204)Pb, (206)Pb, (207)Pb, and (208)Pb) ratios also were determined. The (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios in bran were generally higher than those in rice (P < 0.0001), and rice and bran samples were distinctly different from each other, indicating that Pb isotope composition is an effective for discriminating between bran and rice samples.

  15. Comparison of the concentrations of metal elements and isotopes of lead found in rice and rice bran.

    PubMed

    Dai, Shouhui; Yang, Hui; Yang, Lan; Wang, Fuhua; Du, Ruiying; Wen, Dian

    2014-08-01

    Very few studies have investigated the difference in the distribution of metal elements between rice and rice bran samples. In this study, the concentrations of 27 metal elements (Li, Be, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Ag, Cd, Cs, Ba, Tl, Pb, and U) in 56 polished rice and their corresponding bran samples were determined. A significant difference in concentrations of all elements except Ag and Cd was found between rice and bran (P < 0.05), with bran/rice ratios of 1.21 to 36.3. High concentrations of metal elements, especially that of the heavy metal Cr, in bran samples present a potential safety issue for bran products, such as food and feed containing bran. Pb isotope ((204)Pb, (206)Pb, (207)Pb, and (208)Pb) ratios also were determined. The (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios in bran were generally higher than those in rice (P < 0.0001), and rice and bran samples were distinctly different from each other, indicating that Pb isotope composition is an effective for discriminating between bran and rice samples. PMID:25198608

  16. Lead isotope profiling in dairy calves.

    PubMed

    Buchweitz, John; McClure-Brinton, Kimberly; Zyskowski, Justin; Stensen, Lauren; Lehner, Andreas

    2015-03-01

    Lead (Pb) is a common cause of heavy metal poisonings in cattle. Sources of Pb on farms include crankcase oil, machinery grease, batteries, plumbing, and paint chips. Consequently, consumption of Pb from these sources may negatively impact animal health and Pb may be inadvertently introduced into the food supply. Therefore, the scope of poisoning incidents must be clearly assessed and sources of intoxication identified and strategies to mitigate exposure evaluated and implemented to prevent future exposures. Stable isotope analysis by inductively-coupled plasma mass spectrometry (ICP-MS) has proven itself of value in forensic investigations. We report on the extension of Pb stable isotope analysis to bovine tissues and profile comparisons with paint chips and soils collected from an affected dairy farm to elucidate the primary source. Pb occurs naturally as four stable isotopes: (204)Pb, (206)Pb, (207)Pb, and (208)Pb. Herein a case is reported to illustrate the use of (207)Pb/(206)Pb and (208)Pb/(206)Pb ratios to link environmental sources of exposure with tissues from a poisoned animal. Chemical Pb profiling provides a valuable tool for field investigative approaches to Pb poisoning in production agriculture and is applicable to subclinical exposures.

  17. Field isotopic study of lead fate and compartmentalization in earthworm-soil-metal particle systems for highly polluted soil near Pb recycling factory.

    PubMed

    Goix, Sylvaine; Mombo, Stéphane; Schreck, Eva; Pierart, Antoine; Lévêque, Thibaut; Deola, Frédéric; Dumat, Camille

    2015-11-01

    Earthworms are important organisms in soil macrofauna and play a key role in soil functionality, and consequently in terrestrial ecotoxicological risk assessments. Because they are frequently observed in soils strongly polluted by metals, the influence of earthworm bioturbation on Pb fate could therefore be studied through the use of Pb isotopes. Total Pb concentrations and isotopic composition ((206)Pb, (207)Pb and (208)Pb) were then measured in earthworms, casts and bulk soils sampled at different distance from a lead recycling factory. Results showed decreasing Pb concentrations with the distance from the factory whatever the considered matrix (bulk soils, earthworm bodies or cast samples) with higher concentrations in bulk soils than in cast samples. The bivariate plot (208)Pb/(206)Pb ratios versus (206)Pb/(207)Pb ratios showed that all samples can be considered as a linear mixing between metallic process particulate matter (PM) and geochemical Pb background. Calculated anthropogenic fraction of Pb varied between approximately 84% and 100%. Based on Pb isotopic signatures, the comparison between casts, earthworms and bulk soils allowed to conclude that earthworms preferentially ingest the anthropogenic lead fraction associated with coarse soil organic matter. Actually, soil organic matter was better correlated with Pb isotopic ratios than with Pb content in soils. The proposed hypothesis is therefore a decrease of soil organic matter turnover due to Pb pollution with consequences on Pb distribution in soils and earthworm exposure. Finally, Pb isotopes analysis constitutes an efficient tool to study the influence of earthworm bioturbation on Pb cycle in polluted soils.

  18. Field isotopic study of lead fate and compartmentalization in earthworm-soil-metal particle systems for highly polluted soil near Pb recycling factory.

    PubMed

    Goix, Sylvaine; Mombo, Stéphane; Schreck, Eva; Pierart, Antoine; Lévêque, Thibaut; Deola, Frédéric; Dumat, Camille

    2015-11-01

    Earthworms are important organisms in soil macrofauna and play a key role in soil functionality, and consequently in terrestrial ecotoxicological risk assessments. Because they are frequently observed in soils strongly polluted by metals, the influence of earthworm bioturbation on Pb fate could therefore be studied through the use of Pb isotopes. Total Pb concentrations and isotopic composition ((206)Pb, (207)Pb and (208)Pb) were then measured in earthworms, casts and bulk soils sampled at different distance from a lead recycling factory. Results showed decreasing Pb concentrations with the distance from the factory whatever the considered matrix (bulk soils, earthworm bodies or cast samples) with higher concentrations in bulk soils than in cast samples. The bivariate plot (208)Pb/(206)Pb ratios versus (206)Pb/(207)Pb ratios showed that all samples can be considered as a linear mixing between metallic process particulate matter (PM) and geochemical Pb background. Calculated anthropogenic fraction of Pb varied between approximately 84% and 100%. Based on Pb isotopic signatures, the comparison between casts, earthworms and bulk soils allowed to conclude that earthworms preferentially ingest the anthropogenic lead fraction associated with coarse soil organic matter. Actually, soil organic matter was better correlated with Pb isotopic ratios than with Pb content in soils. The proposed hypothesis is therefore a decrease of soil organic matter turnover due to Pb pollution with consequences on Pb distribution in soils and earthworm exposure. Finally, Pb isotopes analysis constitutes an efficient tool to study the influence of earthworm bioturbation on Pb cycle in polluted soils. PMID:26025429

  19. Lead isotope study of Zn-Pb ore deposits associated with the Basque-Cantabrian basin and Paleozoic basement, Northern Spain

    NASA Astrophysics Data System (ADS)

    Velasco, F.; Pesquera, A.; Herrero, J. M.

    1996-01-01

    A total of forty-three galena samples from syngenetic and epigenetic Pb-Zn mineralizations emplaced in the Lower Cretaceous Basque-Cantabrian basin and Paleozoic basement of the Cinco Villas massif in the western Pyrenees, have been analyzed for Pb-isotopic composition. Galena from sedex mineralizations hosted in Carboniferous clastic rocks in the Cinco Villas massif display an homogeneous lead isotopic signature (206Pb/2044Pb ≈ 18.43, 207Pb/204Pb ≈ 15.66, 208Pb/ 204Pb ≈ 38.69) suggesting a single lead reservoir. These values are slightly more radiogenic than lead from other European Hercynian deposits, possibly reflecting the influence of a more evolved upper crustal source. Underlying Paleozoic sediments are proposed as lead source for the Cinco Villas massif ores. Analyses from twenty-six galena samples from the four strata-bound ore districts hosted in Mesozoic rocks reveal the existence of two populations regarding their lead isotopic composition. Galena from the western Santander districts (e.g., Reocin) is characterized by more radiogenic isotope values (206Pb/204Pb ≈ 18.74, 207Pb/204Pb ≈ 15.67, 208Pb/ 204Pb ≈ 38.73) than those from the central and eastern districts (Troya-Legorreta, Central and Western Vizcaya, 206Pb/204Pb ≈ 18.59, 207Pb/204Pb ≈ 15.66, 208Pb/ 204Pb ≈ 38.73). In all districts, the most likely source for these mineralizations was the thick sequence of Lower Cretaceous clastic sediments. The existence of two separate lead isotopic populations could be the result of regional difference in the composition of the basement rocks and the clastic sediments derived of it or different evolution histories. In both sub-basins, isotopic ratios indicate an increase in crustal influence as the age of the ores decreases.

  20. Multinucleon transfer in O,1816,19F+208Pb reactions at energies near the fusion barrier

    NASA Astrophysics Data System (ADS)

    Rafferty, D. C.; Dasgupta, M.; Hinde, D. J.; Simenel, C.; Simpson, E. C.; Williams, E.; Carter, I. P.; Cook, K. J.; Luong, D. H.; McNeil, S. D.; Ramachandran, K.; Vo-Phuoc, K.; Wakhle, A.

    2016-08-01

    Background: Nuclear reactions are complex, involving collisions between composite systems where many-body dynamics determines outcomes. Successful models have been developed to explain particular reaction outcomes in distinct energy and mass regimes, but a unifying picture remains elusive. The irreversible transfer of kinetic energy from the relative motion of the collision partners to their internal states, as is known to occur in deep inelastic collisions, has yet to be successfully incorporated explicitly into fully quantal reaction models. The influence of these processes on fusion is not yet quantitatively understood. Purpose: To investigate the population of high excitation energies in transfer reactions at sub-barrier energies, which are precursors to deep inelastic processes, and their dependence on the internuclear separation. Methods: Transfer probabilities and excitation energy spectra have been measured in collisions of O,1816,19F+208Pb , at various energies below and around the fusion barrier, by detecting the backscattered projectile-like fragments in a Δ E -E telescope. Results: The relative yields of different transfer outcomes are strongly driven by Q values, but change with the internuclear separation. In 16O+208Pb , single nucleon transfer dominates, with a strong contribution from -2 p transfer close to the Coulomb barrier, though this channel becomes less significant in relation to the -2 p 2 n transfer channel at larger separations. For 18O+208Pb , the -2 p 2 n channel is the dominant charge transfer mode at all separations. In the reactions with 19F,-3 p 2 n transfer is significant close to the barrier, but falls off rapidly with energy. Multinucleon transfer processes are shown to lead to high excitation energies (up to ˜15 MeV), which is distinct from single nucleon transfer modes which predominantly populate states at low excitation energy. Conclusions: Kinetic energy is transferred into internal excitations following transfer, with this

  1. (. pi. sup +- ,. pi. sup +- prime N) reactions on sup 12 C and sup 208 Pb near the giant resonance region

    SciTech Connect

    Yoo, Sung Hoon.

    1990-05-01

    Angular distributions for the {sup 12}C({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p) and {sup 208}Pb({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p or n) reactions near the giant resonance region have been measured at T{sub {pi}} = 180 MeV, and found different between {pi}{sup +} and {pi}{sup {minus}} data. This observation is interpreted as evidence for different excitation mechanisms dominating the {pi}{sup {minus}}-nucleus and {pi}{sup +}-nucleus interactions in the giant resonance region of these targets. A comparison with the single-nucleon knock-out distorted-wave impulse approximation calculations shows, even though these calculations underestimate ({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} N) data for both targets, the dominance of direct process for ({pi}{sup +}, {pi}{sup {plus}}{prime} p) or ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} n) in contrast to ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) or ({pi}{sup +}, {pi}{sup +}{prime} n). In the ({pi}{sup +}, {pi}{sup +}{prime} p) reaction proton-proton hole states are excited directly and appear to have a large probability for direct decay with escape width, whereas in ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) the preferentially excited neutron-neutron hole doorway states couple to resonance states and decay with spreading width. This interpretation led us to suggest that the ratio of cross-sections for inelastic scattering to the giant resonance region should be written in terms of an incoherent sum of cross-sections to neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states contribute incoherently because the different decay processes do not populate the same final states of the residual nucleus.

  2. First observation of high-spin states in {sup 214}Po: Probing the valence space beyond {sup 208}Pb

    SciTech Connect

    Astier, Alain; Porquet, Marie-Genevieve

    2011-01-15

    Excited states in {sup 214}Po have been populated using the {sup 18}O + {sup 208}Pb reaction at 85-MeV beam energy and studied with the Euroball IV {gamma}-multidetector array. The level scheme has been built up to {approx}2.7-MeV excitation energy and spin I=12({h_bar}/2{pi}) from the triple-{gamma} coincidence data. Spin and parity values of most of the observed states have been assigned from the {gamma}-angular properties. The configurations of the yrast states are discussed using results of empirical shell-model calculations and by analogy with the neighboring nuclei. The {sup 214}Po level scheme established in this work constitutes an important step for the determination of the effective nucleon-nucleon interactions beyond N=126.

  3. Spin observables for the {sup 208}Pb(p,n){sup 208}Bi reaction at 135 MeV

    SciTech Connect

    Plumley, M.R.; Watson, J.W.; Anderson, B.D.; Baldwin, A.R.; Madey, R.; Wang, Y.; Foster, C.C.; Wang, Y.; Pella, P.J.; Ramstroem, E.; Unkelbach, W.

    1997-07-01

    We measured the spin observables A{sub y}, P, and S{sub NN{sup {prime}}} for the {sup 208}Pb(p,n){sup 208}Bi reaction at 135 MeV at laboratory angles of 0{degree}, 3{degree}, 6{degree}, and 9{degree}. The overall energy resolution was about 1 MeV. Data for S{sub NN{sup {prime}}} are compared with distorted-wave impulse-approximation calculations that use random-phase approximation wave functions. Comparisons are also made for the {sup 48}Ca(p,n){sup 48}Sc reaction. The agreement between these calculations and the data is generally good, after adjustment of the nucleon-nucleon interaction in the random-phase approximation calculations to place the 0{sup +} isobaric-analog states at the correct excitation energies. A single adjustment of the nucleon-nucleon force works for both target nuclei. {copyright} {ital 1997} {ital The American Physical Society}

  4. Similarity of nuclear structure in the {sup 132}Sn and {sup 208}Pb regions: Proton-neutron multiplets

    SciTech Connect

    Coraggio, L.; Gargano, A.; Covello, A.; Itaco, N.

    2009-08-15

    Starting from the striking similarity of proton-neutron multiplets in {sup 134}Sb and {sup 210}Bi, we perform a shell-model study of nuclei with two additional protons or neutrons to find out to what extent this analogy persists. We employ effective interactions derived from the CD-Bonn nucleon-nucleon potential renormalized by use of the V{sub low-k} approach. The calculated results for {sup 136}Sb, {sup 212}Bi, {sup 136}I, and {sup 212}At are in very good agreement with the available experimental data. The similarity between {sup 132}Sn and {sup 208}Pb regions is discussed in connection with the effective interaction, emphasizing the role of core polarization effects.

  5. New chronometers for the metamorphism of ophiolitic rocks: 40Ar/39Ar neptunite and 232Th/208Pb joaquinite

    NASA Astrophysics Data System (ADS)

    Borneman, N.; Hodges, K. V.; Van Soest, M. C.

    2015-12-01

    Both primary magmatism and metamorphism of ophiolite sequences are difficult to date, due in large part to the fact that the majority of lithologies present tend to contain very low concentrations of radioactive elements. As a result, researchers are often forced to process large amounts of material to search for accessory phases like zircons in gabbro, or to employ geochronometers that often yield multiply interpretable results (e.g., 40Ar/39Ar glaucophane or phengite), or to rely on indirect evidence for inferring ages. Here, we introduce two new options for chronometery of metamorphosed ophiolites: 40Ar/39Ar neptunite and 232Th/208Pb joaquinite. The best known locality for these rare minerals is the New Idria serpentinite diapir, found within the southern Diablo Range of the Coast Range Province of California. Here, both the joaquinite and neptunite chronometers record indistinguishable dates that we interpret to be the crystallization age of the phases during diapir ascent, based on the demonstrated low temperature history of the diapir as whole and the agreement of dates from chromonometers that almost certainly have different closure temperatures. This age is generally inferred to be coincident with the timing of the passage of the Mendocino Triple Junction and associated initiation of the San Andreas fault in this area. We propose that the mean40Ar/39Ar neptunite plateau date of 12.375 ± 0.082 Ma and corroborating 232Th/208Pb joaquinite date (12.08 ± 0.59 Ma) may represent a high-precision constraint on the timing of this event. We also report a second application of these chronometers to samples from the Yarlung suture, which formed at the time of initial India-Eurasia collision in southern Tibet. Here, both chronometers record indistinguishable dates of ca. 52 Ma, which we also interpret as the crystallization age. This age is consistent with most previously published estimates for the timing of the India-Eurasia collision.

  6. Nuclear magnetic resonance spectra and (207)Pb chemical-shift tensors of lead carboxylates relevant to soap formation in oil paintings.

    PubMed

    Catalano, Jaclyn; Yao, Yao; Murphy, Anna; Zumbulyadis, Nicholas; Centeno, Silvia A; Dybowski, Cecil

    2014-01-01

    Soap formation in traditional oil paintings occurs when heavy-metal-containing pigments, such as lead white, 2PbCO3·Pb(OH)2, and lead tin yellow type I, Pb2SnO4, react with fatty acids in the binding medium. These soaps may form aggregates that can be 100-200 μm in diameter, which swell and protrude through the paint surface, resulting in the degradation of the paint film and damage to the integrity of the artwork. The factors that trigger soap formation and the mechanism(s) of the process are not yet well understood. To elucidate these issues, chemical and structural information is necessary, which can be obtained using solid-state (207)Pb and (13)C nuclear magnetic resonance (NMR). In this article, we report (207)Pb and (13)C solid-state NMR spectra and (207)Pb chemical-shift tensors of lead carboxylates implicated in soap formation: lead stearate, lead palmitate, and lead azelate, in addition to lead oleate and lead heptanoate for comparison. The (13)C cross polarization with magic-angle spinning (MAS) spectra of these lead carboxylates show resonance doubling for the carbons closest to the lead, indicating two different conformations of the fatty acid chains in the asymmetric unit. The (207)Pb NMR spectra, from which tensors were determined, were obtained with direct excitation and spin-temperature alternation, with and without MAS, and with the wide band uniform rate smooth truncation Carr-Purcell-Meiboom-Gill pulse sequence. The results of these experiments show that the local coordination environment of lead azelate is different from lead palmitate and lead stearate and could thus be distinguished from these in a paint film displaying soap formation. In addition, comparing the (207)Pb NMR chemical-shift tensors of the lead carboxylates studied shows that crystal packing of the acyl chains may be a factor in determining the coordination environment around the lead. PMID:24666944

  7. Who Needs Uranium? Pb-Pb Dating of (and Temporal Resolution in) Zircon

    NASA Astrophysics Data System (ADS)

    Tera, F.

    2002-12-01

    A method akin to Differential Isotope Correlation (Tera, 2000 and 2002) is applied to 204Pb-depleted systems (e. g., zircons), where 206Pb/ 208Pb and 207Pb/ 208Pb are plotted separately versus the same X-axis of 207Pb/ 206Pb or ( 206Pb/ 208Pb)-( 207Pb/ 208Pb). Because of the general transparency of isotopic ratios to recent U-Pb mobility, these correlations usually project less obscured patterns, which are reiterated in the two diagrams. The redundancy allows correlated filtration of aberrant data, thus resulting in sharper lineation. The justification of filtration through redundancy (FTR) is in the concurrent emergence of synchronism (that is, co-incidence of reason) from the two diagrams. Each judiciously filtered line is the result of mixing of two end-members: (1) initial Pb and (2) in-situ produced Pb (through U and Th decay). A system of a single age can have multiple lines, each corresponding to a specific K = Th / U for the in-situ component. If such a system is not complicated beyond recent mobilities, the lines would converge to intersect at a point corresponding to initial Pb (see Fig. 3, Tera, 1983). The {206, 207, 208}Pb plots mentioned are referred to here as Quasi Differential Diagrams. When the data of the filtered lines, obtained as described above, are plotted on an age-producing diagram of 206Pb/ 208Pb Vs 207Pb/ 208Pb they would produce a single line, the slope of which yields the age as is conventionally calculated. Thus without measuring the often hopelessly non-correlated U (mostly because of prevalent recent U-Pb mobility), a uranium-enriched mineral (e. g., zircon), may be accurately dated. Furthermore, two other aspects of evolution-history may be revealed: (1) In a case where determination of initial Pb on a Quasi Differential Diagram was possible, the age of the source is calculable in a straightforward fashion from the radiogenic ratio of 207Pb/ 206Pb; (2) Events resulting in coexisting re-equilibrated domains may be resolvable into

  8. Lead pollution in subtropical ecosystems on the SE Gulf of California Coast: a study of concentrations and isotopic composition.

    PubMed

    Soto-Jiménez, Martin F; Páez-Osuna, Federico; Scelfo, Genine; Hibdon, Sharon; Franks, Rob; Aggarawl, Jugdeep; Flegal, A Russell

    2008-10-01

    Lead pollution was investigated in environmental matrices and biological indicators collected from two typical subtropical coastal ecosystems in the southeast Gulf of California, Mexico. Lead concentrations and isotopic compositions ((206)Pb/(207)Pb and (208)Pb/(207)Pb) were measured using high resolution inductively-coupled plasma-mass spectrometry (HR-ICP-MS) and thermal ionization mass spectrometry (TIMS), respectively. Lead in surface estuary sediments (10.0-34.2microgg(-1)) and particulate Pb (25.0-128.7microgg(-1), >98% of total Pb) in the water column were significantly higher than levels in natural bedrock soils (15.1+/-8.3microgg(-1)) and river runoff (1.9+/-1.4microgg(-1)). Aquatic plants had Pb concentrations between 2.5 and 7.2microgg(-1), while those in macroalgae ranged from 3 to 5microgg(-1). The ranges of mean Pb concentrations in the aquatic animals studied (ranges in microgg(-1)) were as follows: zooplankton 32+/-3, mussels 2.3-3.9, oysters 1.9-7.9, snail 2.0-7.7, barnacles 0.1-18.5, fish 1.4-8.9, crab 6.3-40.2 and polychaetae 8.5-16.7. Pb values in 20-40% of oyster and fish samples and in all samples of crab exceeded acceptable levels for a food source for human consumption. Pb isotope ratios (206)Pb/(207)Pb, (208)Pb/(207)Pb in biota ranged from 1.188 to 1.206 and 2.448 to 2.470, respectively. A plot of (206)Pb/(207)Pb versus (208)Pb/(207)Pb for the environmental and biological samples collected from two study areas indicates that they contain lead from ores mined in Mexico and used in the past to produce leaded gasoline in use until 1997, natural Pb weathered from the Sierra Madre Occidental mother rock, and the later influence of inputs from a more radiogenic source related to industrial activity in the United States. Statistical software IsoSource results revealed that the Pb contained in environmental matrices and biomonitors is mostly derived from gasoline (20-90%) and US emissions (10-40%).

  9. Lead Isotopes in Highway Runoff

    NASA Astrophysics Data System (ADS)

    Ferreira, M.; Lau, S.; Green, P. G.; Stenstrom, M. K.

    2011-12-01

    Lead (Pb) isotopes have been used extensively to study the provenance of lead pollution on air, water, and sediments. In this study, we measured Pb isotopes and Pb aqueous concentration in highway runoff in three west Los Angeles sites. Those three sites, part of a long-term study sponsored by the California Department of Transportation, represent small catchment areas, and host heavy traffic. In addition, there were no inputs of sand or salt to the highway because the sites are almost completely impervious and also due to the lack of snow to be controlled. Highway runoff from the three sites was collected for 7 storms during the 2004-2005 Winter. Grab samples were collected every 15 minutes during the first hour, and hourly afterwards. A total of 202 samples were collected and filtered into five size fractions (<0.45μm, 0.45-8μm, 8-20μm, 20-100μm, >100μm). Aqueous concentration of Pb range from 0.08μg/L to 46.95μg/L (7.98±10.89μg/L) and it is not correlated with any of the lead isotope ratios. The 208Pb/206Pb ratio ranges from 1.983 to 2.075 (2.024±0.026) and there is no statistical difference for the mean value of the 208Pb/206Pb ratio for the four particulate size fractions (0.45-8μm, 8-20μm, 20-100μm, >100μm). However, the 208Pb/206Pb ratio of nearby soils yield 2.060±0.021 and it is statistically different from the ratios obtained for the highway runoff. This hints that the lead present in highway runoff does not come from local soils. The 207Pb/206Pb ratio ranges from 0.804 to 0.847 (0.827±0.011) and there is no statistical difference for the mean value of the 207Pb/206Pb ratio for the four particulate size fractions (0.45-8μm, 8-20μm, 20-100μm, >100μm). Surprisingly, there is also no statistical difference with the 207Pb/206Pb ratio of nearby soils (0.833±0.009).

  10. Direct ion microprobe U-Pb dating of fossil tooth of a Permian shark

    NASA Astrophysics Data System (ADS)

    Sano, Yuji; Terada, Kentaro

    1999-12-01

    We report here direct ion microprobe dating of fossil tooth (dentine) of a Permian fresh-water shark, Orthacanthus senckenbergianus using the SHRIMP instrument recently installed at Hiroshima University. Fifteen spots on the small sample (approximately 2 mm×1 mm) indicate a 238U/ 206Pb isochron age of 266±18 Ma and a Tera-Wasserburg concordia intercept age of 266±24 Ma in a three-dimensional 238U/ 206Pb- 207Pb/ 206Pb- 204Pb/ 206Pb diagram. These Permian ages are consistent with a 235U/ 207Pb age of 453±170 Ma and a 232Th- 208Pb age of 235±310 Ma, suggesting indistinguishable depositional and early diagenetic ages of the fossil in its sedimentary sequences. The success of the method depends on the chemical fractionation of uranium from lead in a specimen a few hundred microns in size and the consequent variations in lead isotopic compositions due to radioactive decay.

  11. 207Pb NMR in minium, Pb3O4: Evidence for the [Pb2]4+ ion andpossible relativistic effects in the Pb-Pb bond

    SciTech Connect

    Gabuda, S.P.; Kozlova, S.G.; Terskikh, V.V.; Dybowski, C.; Neue,G.; Perry, D.L.

    1999-07-18

    Solid Pb3O4 has been studied with 207Pb nuclear magnetic resonance (NMR) spectroscopy. The 207Pb NMR chemical-shift tensor of the Pb2+ site has principal values of delta 11=1980+-5 ppm, delta 22=1540+-5ppm, and delta 33=-1108+-10 ppm; delta iso=804+-10 ppm. The chemical-shift tensor of the Pb4+ site is axial, with principal values delta bar bar=-1009+-3 ppm and delta perpendicular=1132+-3 ppm; delta iso=-1091+-3ppm. The Pb4+ Pb2+ scalar coupling constant JPb Pb=2.3+-0.1 kHz. The main contribution to the Pb2+ chemical-shift anisotropy is proposed to arise from an exchange interaction in the Pb2+ Pb2+ pairs, conventionally regarded as molecular [Pb2]4+ ions.

  12. Double-magic nature of 132Sn and 208Pb through lifetime and cross-section measurements

    SciTech Connect

    Allmond, James M; Stuchbery, Andrew E; Beene, James R; Galindo-Uribarri, Alfredo {nmn}; Liang, J Felix; Padilla-Rodal, Elizabeth; Radford, David C; Varner Jr, Robert L; Ayres, A.; Batchelder, J. C.; Bey, A.; Bingham, C. R.; Howard, Meredith E; Jones, K. L.; Manning, Brett M; Mueller, Paul Edward; Nesaraja, Caroline D; Pain, Steven D; Peters, William A; Ratkiewicz, Andrew J; Schmitt, Kyle; Shapira, Dan; Smith, Michael Scott; Stone, N. J.; Stracener, Daniel W; Yu, Chang-Hong

    2014-01-01

    Single-neutron states in 133Sn and 209Pb, which are analogous to single electrons outside of closed atomic shells in alkali metals, were populated by the (9Be,8Be) one-neutron transfer reaction in inverse kinematics using particle-gamma coincidence spectroscopy. In addition, the s1/2 single-neutron hole-state candidate in 131Sn was populated by (9Be,10Be). Doubly closed-shell 132Sn (radioactive) and 208Pb (stable) beams were used at sub-Coulomb barrier energies of 3 MeV per nucleon. Level energies, gamma-ray transitions, absolute cross sections, spectroscopic factors, asymptotic normalization coefficients, and excited-state lifetimes are reported and compared to shell-model expectations. The results include a new transition and precise level energy for the 3p1/2 candidate in 133Sn, new absolute cross sections for the 1h9/2 candidate in 133Sn and 3s1/2 candidate in 131Sn, and new lifetimes for excited states in 133Sn and 209Pb. This is the first report on excited-state lifetimes of 133Sn, which provide a unique signature of the single-neutron states and 132Sn double-shell closure.

  13. A Study of the Nuclear Resonance Fluorescence Reaction Yield Dependence on the Target Thickness of 208PB

    NASA Astrophysics Data System (ADS)

    Negm, Hani; Daito, Izuru; Zen, Heishun; Kii, Toshiteru; Masuda, Kai; Hori, Toshitada; Ohgaki, Hideaki; Hajima, Ryoichi; Shizuma, Toshiyuki; Hayakawa, Takehito; Kikuzawa, Nobuhiro; Toyokawa, Hiroyuki

    2015-10-01

    We have been developing an active, non-destructive detection system based on nuclear resonance fluorescence (NRF) for inspecting special nuclear materials (SNMs) such as 235U in a container at a seaport. The study of the NRF yield dependence on the target thickness of SNMs is required to evaluate the performance of the inspection system. To this end, an NRF experiment has been performed using a laser Compton backscattering γ-ray beam line at New SUBARU in 208Pb. Cylindrical shaped natural lead targets with a 0.5 cm radius and varying thicknesses of 1.0, 1.44, and 3.05 cm were irradiated at a resonance energy of 7.332 MeV. The NRF yield was detected using two HPG detectors with relative efficiencies of 120% and 100% positioned at scattering angles of 90° and 130°, respectively, relative to the incident γ-ray beam. As a result, the NRF yield exhibited a saturation behavior for the thick lead target. An analytic treatment and Monte Carlo simulation using GEANT4 was performed to interpret the reaction yield (RY) of the NRF interaction. The simulation result is in good agreement with the experimental data for the target thickness dependence. The analytic treatment, the NRF RY model, is also in reasonable agreement.

  14. Sensitivity of neutron radii in a {sup 208}Pb nucleus and a neutron star to nucleon-{sigma}-{rho} coupling corrections in relativistic mean field theory

    SciTech Connect

    Shen, G.; Li, J.; Hillhouse, G.C.; Meng, J.

    2005-01-01

    We study the sensitivity of the neutron skin thickness S in a {sup 208}Pb nucleus to the addition of nucleon-{sigma}-{rho} coupling corrections to a selection (PK1, NL3, S271, and Z271) of interactions in a relativistic mean field model. The PK1 and NL3 effective interactions lead to a minimum value of S= 0.16 fm in comparison with the original value of S= 0.28 fm. The S271 and Z271 effective interactions yield even smaller values of S= 0.11 fm, which are similar to those for nonrelativistic mean field models. A precise measurement of the neutron radius, and therefore S, in {sup 208}Pb will place an important constraint on both relativistic and nonrelativistic mean field models. We also study the correlation between the radius of a 1.4-solar-mass neutron star and S.

  15. Relevance of single-particle and collective excitations in zirconium isotopes populated by neutron transfer reactions in the {sup 90}Zr+{sup 208}Pb system

    SciTech Connect

    Pajtler, M. Varga; Szilner, S.; Malenica, D. Jelavić; Mijatović, T.; Soić, N.; Corradi, L.; Angelis, G. de; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Valiente-Dobón, J. J.; Gadea, A.; Haas, F.; Lunardi, S.; Mengoni, D.; Montagnoli, G.; Recchia, F.; Scarlassara, F.; Märginean, N.; Pollarolo, G.; and others

    2015-10-15

    Multineutron transfer reaction {sup 90}Zr+{sup 208}Pb has been studied at the energy close to the Coulomb barrier energy by using the PRISMA + CLARA set-up. In this fragment-γ coincidence measurement, the selective properties of the reaction mechanism in the population of the specific states have been discussed. Based on the observed γ transitions of neutron transfer channels, namely {sup 89–94}Zr isotopes, their level schemes have been constructed and updated.

  16. Regional variations in the lead isotopic composition of galena from southern Korea with implications for the discrimination of lead provenance

    NASA Astrophysics Data System (ADS)

    Jeong, Youn-Joong; Cheong, Chang-sik; Shin, Dongbok; Lee, Kwang-Sik; Jo, Hui Je; Gautam, Mukesh Kumar; Lee, Insung

    2012-11-01

    This study presents a comprehensive database (n = 215) of lead isotopes in galena from the southern Korean peninsula using new and published data. Of the 69 metal mines examined, predominantly skarn- and hydrothermal-type Pb-Zn-Au-Ag-Cu deposits were observed and were associated with Mesozoic magmatic activities. Galena samples from each geotectonic unit showed discrete lead isotopic signatures. The Gyeongsang basin samples were characteristically unradiogenic and had restricted variations in lead isotopic composition (206Pb/204Pb = 18.16-18.59, 207Pb/204Pb = 15.48-15.64, 208Pb/204Pb = 37.87-38.77). Their 208Pb/204Pb range indicated an involvement of source materials less thorogenic than the associated granites. The galena samples from Cambro-Ordovician carbonate rocks of the northeastern Yeongnam massif and eastern Taebaeksan basin had the most radiogenic 206Pb/204Pb (19.28 ± 0.14) and 207Pb/204Pb (15.833 ± 0.027) ratios. Their lead isotopic trend indicated a combined contribution of ore lead from granitic magmas, Precambrian basements, and overlain host rocks. Less radiogenic galena samples from the middle to southwestern parts of the Yeongnam massif and Okcheon belt showed limited lead isotopic variations (206Pb/204Pb = 18.332 ± 0.065, 207Pb/204Pb = 15.693 ± 0.012, 208Pb/204Pb = 38.93 ± 0.07 on average), probably resulted from mixing with a common crustal basement. The differences in lead isotopes between the radiogenic and unradiogenic groups from the Yeongnam massif and Okcheon belt may reflect the spatial dissimilarity of involved crustal rocks. The old crust appears to have significantly contributed ore lead to galenas from the western Gyeonggi massif, but the geochronological meaning of their steep 207Pb/204Pb-206Pb/204Pb trend is not clear. The comprehensive database constructed by the present study suggests that lead province in the southern Korean peninsula may be subdivided into four discrete zones. Linear discriminant analysis showed that more

  17. Single particle structure of 209,210Pb and 206Hg investigated through the deep inelastic reaction 136Xe +208 Pb

    NASA Astrophysics Data System (ADS)

    Hamill, C. R.; McCutchan, E. A.; Sonzogni, A. A.; Barrett, J. S.; Loveland, W.; Yanez, R.; Zhu, S.; Ayangeakaa, A. D.; Carpenter, M. P.; Greene, J. P.; Janssens, R. V. F.; Lauritsen, T.; Chiara, C. J.; Harker, J. L.; Walters, W. B.; Brown, A. B.

    2015-10-01

    The region of nuclei around 208Pb is rich in information relevant to nuclear structure and astrophysics, yet is relatively unexplored. To access these nuclei, a deep inelastic reaction was performed at Argonne National Laboratory's Gammasphere, where a 136Xe beam was incident on a 208Pb target. Our analysis focused on209Pb, 210Pb and 206Hg, and our findings of new relevant information include energy level schemes, angular correlations resulting in level spins and gamma-ray multipolarities, and half-lives of isomeric states. Known transitions in these nuclei were observed and confirmed and coincidence techniques were used to expand upon this data to discover new excited states. The results from this study were compared to theoretical shell model calculations and states interpreted in terms of valence nucleon excitation or coupling of the extra neutron(s) or proton holes to the double magic (Z = 82, N =126) 208Pb core. Results will be presented. Supported by US DOE under the SULI Program and Award No. DE-FG06-97ER41026 and No. DE-FG02-94ER40834 and Contract No. DE-AC02-06CH11357 and No. DE-AC02-06CH10886.

  18. Metallic elements and isotope of Pb in wet precipitation in urban area, South America

    NASA Astrophysics Data System (ADS)

    Migliavacca, Daniela Montanari; Teixeira, Elba Calesso; Gervasoni, Fernanda; Conceição, Rommulo Vieira; Raya Rodriguez, Maria Teresa

    2012-04-01

    The atmosphere of urban areas has been the subject of many studies to show the atmospheric pollution in large urban centers. By quantifying wet precipitation through the analysis of metallic elements (ICP/AES) and Pb isotopes, the wet precipitation of the Metropolitan Area of the Porto Alegre (MAPA), Brazil, was characterized. The samples were collected between July 2005 and December 2007. Zn, Fe and Mn showed the highest concentration in studied sites. Sapucaia do Sul showed the highest average for Zn, due to influence by the steel plant located near the sampling site. The contribution of anthropogenic emissions from vehicular activity and steel plants in wet precipitation and suspended particulate matter in the MAPA was identified by the isotopic signatures of 208Pb/207Pb and 206Pb/207Pb. Moreover the analyses of the metallic elements allowed also to identify the contribution of other anthropic sources, such as steel plants and oil refinery.

  19. Pb Isotopes Track Asian Pollution in California

    NASA Astrophysics Data System (ADS)

    Ewing, S. A.; Christensen, J. N.; Brown, S. T.; Vancuren, R. A.; Cliff, S. S.; Depaolo, D. J.

    2008-12-01

    The transport of Asian pollution to North America has broad implications for global climate models and regional air quality regulation. In the western US, rising atmospheric Pb levels have been evident since the mid-1990s despite the phase-out of leaded gasoline. We use Pb isotopes to fingerprint the trans-Pacific component of atmospheric pollution in California. We measured Pb isotopes in airborne particles collected at two sites west (Mt. Tamalpais) and east (Chabot Observatory, Oakland Hills) of the San Francisco Bay Area, from winter 2007 through late spring 2008. We also analyzed archived springtime samples from inland sites throughout central California. Wintertime values of 206Pb/207Pb vs. 208Pb/207Pb at Chabot Observatory form a linear array that is consistent with published data for San Francisco Bay waters, whereas published values for Chinese cities and loess fall along a separate and distinct array for that region, consistent with our analysis of samples collected at Hefei, China in 2002. Between March and May 2008, the Tamalpais and Chabot samples diverge from the California regional array toward the Chinese array. About half of the central California samples also show a strong Asian influence. We quantify the divergence of values from the regional California array as Δ208Pb = (208Pb/207Pb)expected - (208Pb/207Pb) )observed, where (208Pb/207Pb)expected is derived from a linear fit to the wintertime samples at Chabot Observatory. These Δ208Pb values increase between winter and spring at both Mt. Tamapais and Chabot Observatory, and are higher at Mt. Tamalpais, despite lower Pb concentrations at that site. They indicate that up to 80% of the Pb in the Tamalpais samples, and up to 40% of the Pb in the Chabot Observatory samples, reflect trans-Pacific transport. The lower proportion in the Chabot samples -- where there is often more Pb -- indicates dilution by local urban sources. Our data provide conclusive evidence of Asian air pollution reaching

  20. Impact of submersible pumps on Pb constituents in residential wells.

    PubMed

    Sidle, W C; Li, P

    2008-02-01

    Dissolved Pb in 51 domestic wells screened from 18 to 48 m in glacial tills and outwash deposits were examined in conjunction with the characteristics of their corresponding submersible pump. Pb concentrations, ranging from 0.8 to 24.9 microg l(-1), entering residential water supplies were measured during 2001-2004 in the Royal watershed, Maine. Principal component analyses assisted the weighting of pump age, well screen depth, and draw time variables. Preliminary Pb sequestration significance in the boreholes was predicted from geochemical speciation and synchrotron XAS analyses. Nascent 207Pb/206Pb and 208Pb/206Pb isotope analyses assisted the discrimination of possibly leached Pb from submersible pump materials among geogenic sources.

  1. Pb, Sr, and Nd isotopes in basalts and sulfides from the Juan de Fuca Ridge

    NASA Technical Reports Server (NTRS)

    Hegner, E.; Tatsumoto, M.

    1987-01-01

    Isotopic Pb, Sr, and Nd data were collected by the Alvin submersible from seven basalt glasses in the southern Juan de Fuca Ridge (JFR), giving similar ratios for Pb-206/Pb-204 of about 18.45, for Pb-207/Pb-204 of about 15.47, for Pb-208/Pb-204 of about 37.81, for Sr-87/Sr-86 of about 0.70249, and for Nd-143/Nd-144 of about 0.51315. Data suggest that the basalts are all cogenetic, and that four of the samples are also comagmatic. It is concluded that isotopic data for the JFR and seamount basalts provide additional support for the mantle blob cluster model (Allegre et al., 1984), suggesting the involvement of multiple components in the genesis of ridge basalts, and including an unusual end-member that has nonradiogenic Sr and variable Pb-206/Pb-204 isotopic compositions.

  2. Tracing fetal and childhood exposure to lead using isotope analysis of deciduous teeth.

    PubMed

    Shepherd, Thomas J; Dirks, Wendy; Roberts, Nick M W; Patel, Jaiminkumar G; Hodgson, Susan; Pless-Mulloli, Tanja; Walton, Pamela; Parrish, Randall R

    2016-04-01

    We report progress in using the isotopic composition and concentration of Pb in the dentine and enamel of deciduous teeth to provide a high resolution time frame of exposure to Pb during fetal development and early childhood. Isotope measurements (total Pb and (208)Pb/(206)Pb, (207)Pb/(206)Pb ratios) were acquired by laser ablation inductively coupled mass spectrometry at contiguous 100 micron intervals across thin sections of the teeth; from the outer enamel surface to the pulp cavity. Teeth samples (n=10) were selected from two cohorts of children, aged 5-8 years, living in NE England. By integrating the isotope data with histological analysis of the teeth, using the daily incremental lines in dentine, we were able to assign true estimated ages to each ablation point (first 2-3 years for molars, first 1-2 years for incisors+pre-natal growth). Significant differences were observed in the isotope composition and concentration of Pb between children, reflecting differences in the timing and sources of exposure during early childhood. Those born in 2000, after the withdrawal of leaded petrol in 1999, have the lowest dentine Pb levels (<0.2µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.126-2.079) (208)Pb/(206)Pb (mean ±2σ: 0.879-0.856) ratios that correlate very closely with modern day Western European industrial aerosols (PM10, PM2.5) suggesting that diffuse airborne pollution was probably the primary source and exposure pathway. Legacy lead, if present, is insignificant. For those born in 1997, dentine lead levels are typically higher (>0.4µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.145-2.117) (208)Pb/(206)Pb (mean ±2σ: 0.898-0.882) ratios that can be modelled as a binary mix between industrial aerosols and leaded petrol emissions. Short duration, high intensity exposure events (1-2 months) were readily identified, together with evidence that dentine provides a good proxy for childhood changes in the isotope composition of blood Pb. Our pilot study confirms that

  3. Tracing fetal and childhood exposure to lead using isotope analysis of deciduous teeth.

    PubMed

    Shepherd, Thomas J; Dirks, Wendy; Roberts, Nick M W; Patel, Jaiminkumar G; Hodgson, Susan; Pless-Mulloli, Tanja; Walton, Pamela; Parrish, Randall R

    2016-04-01

    We report progress in using the isotopic composition and concentration of Pb in the dentine and enamel of deciduous teeth to provide a high resolution time frame of exposure to Pb during fetal development and early childhood. Isotope measurements (total Pb and (208)Pb/(206)Pb, (207)Pb/(206)Pb ratios) were acquired by laser ablation inductively coupled mass spectrometry at contiguous 100 micron intervals across thin sections of the teeth; from the outer enamel surface to the pulp cavity. Teeth samples (n=10) were selected from two cohorts of children, aged 5-8 years, living in NE England. By integrating the isotope data with histological analysis of the teeth, using the daily incremental lines in dentine, we were able to assign true estimated ages to each ablation point (first 2-3 years for molars, first 1-2 years for incisors+pre-natal growth). Significant differences were observed in the isotope composition and concentration of Pb between children, reflecting differences in the timing and sources of exposure during early childhood. Those born in 2000, after the withdrawal of leaded petrol in 1999, have the lowest dentine Pb levels (<0.2µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.126-2.079) (208)Pb/(206)Pb (mean ±2σ: 0.879-0.856) ratios that correlate very closely with modern day Western European industrial aerosols (PM10, PM2.5) suggesting that diffuse airborne pollution was probably the primary source and exposure pathway. Legacy lead, if present, is insignificant. For those born in 1997, dentine lead levels are typically higher (>0.4µgPb/g) with (208)Pb/(206)Pb (mean ±2σ: 2.145-2.117) (208)Pb/(206)Pb (mean ±2σ: 0.898-0.882) ratios that can be modelled as a binary mix between industrial aerosols and leaded petrol emissions. Short duration, high intensity exposure events (1-2 months) were readily identified, together with evidence that dentine provides a good proxy for childhood changes in the isotope composition of blood Pb. Our pilot study confirms that

  4. Lead Isotope Characterization of Petroleum Fuels in Taipei, Taiwan

    PubMed Central

    Yao, Pei-Hsuan; Shyu, Guey-Shin; Chang, Ying-Fang; Chou, Yu-Chen; Shen, Chuan-Chou; Chou, Chi-Su; Chang, Tsun-Kuo

    2015-01-01

    Leaded gasoline in Taiwan was gradually phased out from 1983 to 2000. However, it is unclear whether unleaded gasoline still contributes to atmospheric lead (Pb) exposure in urban areas. In this study, Pb isotopic compositions of unleaded gasolines, with octane numbers of 92, 95, 98, and diesel from two local suppliers in Taipei were determined by multi-collector inductively coupled plasma mass spectrometry with a two-sigma uncertainty of ± 0.02 %. Lead isotopic ratios of vehicle exhaust (208Pb/207Pb: 2.427, 206Pb/207Pb: 1.148, as estimated from petroleum fuels) overlap with the reported aerosol data. This agreement indicates that local unleaded petroleum fuels, containing 10–45 ng·Pb·g−1, are merely one contributor among various sources to urban aerosol Pb. Additionally, the distinction between the products of the two companies is statistically significant in their individual 208Pb/206Pb ratios (p-value < 0.001, t test). Lead isotopic characterization appears to be applicable as a “fingerprinting” tool for tracing the sources of Pb pollution. PMID:25918913

  5. Lead and strontium isotopic evidence for crustal interaction and compositional zonation in the source regions of Pleistocene basaltic and rhyolitic magmas of the Coso volcanic field, California

    USGS Publications Warehouse

    Bacon, C.R.; Kurasawa, H.; Delevaux, M.H.; Kistler, R.W.; Doe, B.R.

    1984-01-01

    The isotopic compositions of Pb and Sr in Pleistocene basalt, high-silica rhyolite, and andesitic inclusions in rhyolite of the Coso volcanic field indicate that these rocks were derived from different levels of compositionally zoned magmatic systems. The 2 earliest rhyolites probably were tapped from short-lived silicic reservoirs, in contrast to the other 36 rhyolite domes and lava flows which the isotopic data suggest may have been leaked from the top of a single, long-lived magmatic system. Most Coso basalts show isotopic, geochemical, and mineralogic evidence of interaction with crustal rocks, but one analyzed flow has isotopic ratios that may represent mantle values (87Sr/86Sr=0.7036,206Pb/204Pb=19.05,207Pb/204Pb=15.62,208Pb/204Pb= 38.63). The (initial) isotopic composition of typical rhyolite (87Sr/86Sr=0.7053,206Pb/204Pb=19.29,207Pb/204Pb= 15.68,208Pb/204Pb=39.00) is representative of the middle or upper crust. Andesitic inclusions in the rhyolites are evidently samples of hybrid magmas from the silicic/mafic interface in vertically zoned magma reservoirs. Silicic end-member compositions inferred for these mixed magmas, however, are not those of erupted rhyolite but reflect the zonation within the silicic part of the magma reservoir. The compositional contrast at the interface between mafic and silicic parts of these systems apparently was greater for the earlier, smaller reservoirs. ?? 1984 Springer-Verlag.

  6. High-precision measurements of seawater Pb isotope compositions by double spike thermal ionization mass spectrometry.

    PubMed

    Paul, Maxence; Bridgestock, Luke; Rehkämper, Mark; van DeFlierdt, Tina; Weiss, Dominik

    2015-03-10

    A new method for the determination of seawater Pb isotope compositions and concentrations was developed, which combines and optimizes previously published protocols for the separation and isotopic analysis of this element. For isotopic analysis, the procedure involves initial separation of Pb from 1 to 2L of seawater by co-precipitation with Mg hydroxide and further purification by a two stage anion exchange procedure. The Pb isotope measurements are subsequently carried out by thermal ionization mass spectrometry using a (207)Pb-(204)Pb double spike for correction of instrumental mass fractionation. These methods are associated with a total procedural Pb blank of 28±21 pg (1sd) and typical Pb recoveries of 40-60%. The Pb concentrations are determined by isotope dilution (ID) on 50 mL of seawater, using a simplified version of above methods. Analyses of multiple aliquots of six seawater samples yield a reproducibility of about ±1 to ±10% (1sd) for Pb concentrations of between 7 and 50 pmol/kg, where precision was primarily limited by the uncertainty of the blank correction (12±4 pg; 1sd). For the Pb isotope analyses, typical reproducibilities (±2sd) of 700-1500 ppm and 1000-2000 ppm were achieved for (207)Pb/(206)Pb, (208)Pb/(206)Pb and (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)Pb, respectively. These results are superior to literature data that were obtained using plasma source mass spectrometry and they are at least a factor of five more precise for ratios involving the minor (204)Pb isotope. Both Pb concentration and isotope data, furthermore, show good agreement with published results for two seawater intercomparison samples of the GEOTRACES program. Finally, the new methods were applied to a seawater depth profile from the eastern South Atlantic. Both Pb contents and isotope compositions display a smooth evolution with depth, and no obvious outliers. Compared to previous Pb isotope data for seawater, the (206)Pb/(204)Pb ratios are well correlated

  7. Regional lead isotope study of a polluted river catchment: River Wear, Northern England, UK.

    PubMed

    Shepherd, Thomas J; Chenery, Simon R N; Pashley, Vanessa; Lord, Richard A; Ander, Louise E; Breward, Neil; Hobbs, Susan F; Horstwood, Matthew; Klinck, Benjamin A; Worrall, Fred

    2009-08-15

    High precision, lead isotope analyses of archived stream sediments from the River Wear catchment, northeast England (1986-88), provide evidence for three main sources of anthropogenic lead pollution; lead mining, industrial lead emissions and leaded petrol. In the upper catchment, pollution is totally controlled and dominated by large lead discharges from historic mining centres in the North Pennine Orefield ((208)Pb/(206)Pb, (207)Pb/(206)Pb ratios range from 2.0744-2.0954 and 0.8413-0.8554 respectively). In the lower catchment, co-extensive with the Durham Coalfield and areas of high population density, pollution levels are lower and regionally more uniform. Isotope ratios are systematically higher than in the upper catchment ((208)Pb/(206)Pb, (207)Pb/(206)Pb ratios range from 2.0856-2.1397 and 0.8554-0.8896 respectively) and far exceed values determined for the geogenic regional background. Here, the pollution is characterised by the atmospheric deposition of industrial lead and petrol lead. Lead derived from the combustion of coal, although present, is masked by the other two sources. Recent sediments from the main channel of the River Wear are isotopically indistinguishable from older, low order stream sediments of the North Pennine Orefield, indicating that contamination of the river by lead mining waste (up to several 1000 mg/kg Pb at some locations) continues to pose an environmental problem; a pattern that can be traced all the way to the tidal reach. Using within-catchment isotope variation and sediment lead concentrations, estimates can be made of the discharges from discrete mines or groups of mines to the overall level of lead pollution in the River Wear. As well as providing information pertinent to source apportionment and on-going catchment remediation measures, the database is a valuable resource for epidemiologists concerned with the health risks posed by environmental lead.

  8. [Heavy metal contamination and Pb isotopic composition in natural soils around a Pb/Zn mining and smelting area].

    PubMed

    Sun, Rui; Shu, Fan; Hao, Wei; Li, Li; Sun, Wei-Ling

    2011-04-01

    The heavy metal (Pb, Zn, Cr, Cu, Cd, and Hg) concentrations in the A horizon and C horizon soils, collected around the Pb/Zn mining and smelting area of Shuikoushan in Hunan, China, were investigated, and the Pb isotopic compositions were also determined to identify the potential origin of Pb in the A horizon soil. Compared with C horizon soils, the A horizon soils exhibit elevated heavy metal concentrations, especially in the vicinity of the mining and smelting area. This reveals that the surface soil was contaminated to some degree. The contents of Pb, Zn, Cr, Cu, Cd, and Hg in soils are up to 3966.88, 2086.25, 135.31, 185.63, 56.15, and 16.434 mg/kg, respectively. The potential risks caused by different metals are in the order of Cd > Hg > Pb > Cu > Zn = Cr. Much higher potential ecological risk was observed for the central area (Shuikoushan Pb/Zn mining and smelting area) than for the surrounding area. About 34%, 33%, 11%, and 22% of the sampling sites demonstrate low, moderate, considerable, and very high potential ecological risk in the central area, while about 68%, 16%, 10%, and 6% of the sampling sites show low, moderate, considerable, and very high potential ecological risk in the surrounding area, respectively. Compared with the Pb isotopic compositions in the C horizon soils (206Pb/207Pb 1.168-1.246, 208 Pb/206 Pb 2.014-2.130), the Pb in the A horizon soils has lower 206 Pb/207Pb ratios (1.166-1.226) and higher 208Pb/206Pb ratios (2.043-2. 135). The Pb in the A horizon soils predominantly derives from two-component mixing resources. One is the parent materials of C horizon, and the other is the atmospheric deposition of the smelting flue gas dust.

  9. Isotopic characterisation of lead in contaminated soils from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria.

    PubMed

    Bacon, Jeffrey R; Dinev, Nikolai S

    2005-03-01

    Soil samples from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria contained very high concentrations of cadmium, lead and zinc (up to 140, 4900 and 5900 mg kg(-1), respectively). A roadside soil in a relatively uncontaminated area also contained high concentrations of the same metals (24, 1550 and 1870 mg kg(-1), respectively) indicating that the transport of ores could be a source of contamination. Even though the lead isotope ratios in all the samples fell within a very narrow range (for example, 1.186-1.195 for (206)Pb/(207)Pb), the samples could be differentiated into three distinct groups: ores ((206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of 1.1874-1.1884 and 2.4755-2.4807, respectively), current deposition (1.1864 and 2.4704-2.4711, respectively) and local background (1.1927-1.1951 and 2.4772-2.4809, respectively). Although most of the current deposition has its origin in the ores used at the smelter, up to 12% could be from other sources such as petrol lead.

  10. Temporal evolution of lead isotope ratios in sediments of the Central Portuguese Margin: a fingerprint of human activities.

    PubMed

    Mil-Homens, Mário; Caetano, Miguel; Costa, Ana M; Lebreiro, Susana; Richter, Thomas; de Stigter, Henko; Trancoso, Maria A; Brito, Pedro

    2013-09-15

    Stable Pb isotope ratios ((206)Pb/(207)Pb, (208)Pb/(206)Pb), (210)Pb, Pb, Al, Ca, Fe, Mn and Si concentrations were measured in 7 sediment cores from the west coast of the Iberian Peninsula to assess the Pb contamination throughout the last 200 years. Independently of their locations, all cores are characterized by increasing Pb/Al rends not related to grain-size changes. Conversely, decreasing trends of (206)Pb/(207)Pb were found towards the present. This tendency suggest a change in Pb sources reflecting an increased proportion derived from anthropogenic activities. The highest anthropogenic Pb inventories for sediments younger than 1950s were found in the two shallowest cores of Cascais and Lisboa submarine canyons, reflecting the proximity of the Tagus estuary. Lead isotope signatures also help demonstrate that sediments contaminated with Pb are not constrained to estuarine-coastal areas and upper parts of submarine canyons, but are also to transferred to a lesser extent to deeper parts of the Portuguese Margin.

  11. Temporal evolution of lead isotope ratios in sediments of the Central Portuguese Margin: a fingerprint of human activities.

    PubMed

    Mil-Homens, Mário; Caetano, Miguel; Costa, Ana M; Lebreiro, Susana; Richter, Thomas; de Stigter, Henko; Trancoso, Maria A; Brito, Pedro

    2013-09-15

    Stable Pb isotope ratios ((206)Pb/(207)Pb, (208)Pb/(206)Pb), (210)Pb, Pb, Al, Ca, Fe, Mn and Si concentrations were measured in 7 sediment cores from the west coast of the Iberian Peninsula to assess the Pb contamination throughout the last 200 years. Independently of their locations, all cores are characterized by increasing Pb/Al rends not related to grain-size changes. Conversely, decreasing trends of (206)Pb/(207)Pb were found towards the present. This tendency suggest a change in Pb sources reflecting an increased proportion derived from anthropogenic activities. The highest anthropogenic Pb inventories for sediments younger than 1950s were found in the two shallowest cores of Cascais and Lisboa submarine canyons, reflecting the proximity of the Tagus estuary. Lead isotope signatures also help demonstrate that sediments contaminated with Pb are not constrained to estuarine-coastal areas and upper parts of submarine canyons, but are also to transferred to a lesser extent to deeper parts of the Portuguese Margin. PMID:23871578

  12. Lead contamination and transfer in urban environmental compartments analyzed by lead levels and isotopic compositions.

    PubMed

    Hu, Xin; Sun, Yuanyuan; Ding, Zhuhong; Zhang, Yun; Wu, Jichun; Lian, Hongzhen; Wang, Tijian

    2014-04-01

    Lead levels and isotopic compositions in atmospheric particles (TSP and PM2.5), street dust and surface soil collected from Nanjing, a mega city in China, were analyzed to investigate the contamination and the transfer of lead in urban environmental compartments. The lead contents in TSP and PM2.5 are significantly higher than them in the surface soil and street dust (p < 0.05). The enrichment factor using the mass ratio of lead to the major crustal elements (Al, Sr, Ti and Fe) indicates significant lead enrichment in atmospheric particles. The plots of (206)Pb/(207)Pb vs.(208)Pb/(206)Pb and (206)Pb/(207)Pb vs. 1/Pb imply that the street dust and atmospheric particles (TSP and PM2.5) have very similar lead sources. Coal emissions and smelting activities may be the important lead sources for street dust and atmospheric particles (TSP and PM2.5), while the deposition of airborne lead is an important lead source for urban surface soil.

  13. Nuclear potentials for sub-barrier fusion and cluster decay in {sup 14}C, {sup 18}O+{sup 208}Pb systems

    SciTech Connect

    Sagaidak, R. N.; Tretyakova, S. P.; Khlebnikov, S. V.; Ogloblin, A. A.; Rowley, N.; Trzaska, W. H.

    2007-09-15

    Near-barrier fusion excitation functions for the {sup 14}C and {sup 18}O+{sup 208}Pb reactions have been analyzed in the framework of the barrier-passing model using different forms of the nuclear potential and the phenomenology of a fluctuating barrier. The best-fit fusion potentials were used to estimate cluster decay probabilities from the corresponding ground states of Ra and Th (i.e., for the inverse decay process). The analysis supports the ''{alpha}-decay-like'' scenario for carbon and oxygen emission from these nuclei.

  14. Source assessment of atmospheric lead measured at Ny-Ålesund, Svalbard

    NASA Astrophysics Data System (ADS)

    Bazzano, Andrea; Ardini, Francisco; Becagli, Silvia; Traversi, Rita; Udisti, Roberto; Cappelletti, David; Grotti, Marco

    2015-07-01

    Size-segregated (PM10) aerosol samples were collected at Ny-Ålesund (Svalbard Islands, Norwegian Arctic) from April to September 2012 and analysed for lead content and isotopic composition (207Pb/206Pb and 208Pb/206Pb), along with other chemical tracers, such as aluminium (crustal marker) and non-sea-salt sulphates (anthropogenic and marine biogenic marker). It was found that most of lead reaching Ny-Ålesund is anthropogenic, with a marked seasonality of both the concentration and isotopic signature. Particularly, average lead concentration in summer was significantly lower than in spring (p = 0.003), whereas 208Pb/206Pb decreased from 2.107 ± 0.002 to 2.090 ± 0.005 (mean ± 95%-confidence level, p = 6.0 10-6). A comparison of the measured isotopic ratios to literature data suggests that the atmospheric lead reaching the Arctic during spring can be mainly related to inputs from eastern Eurasia, whereas North America appeared to be the major source during the summer. Experimental results and sampling strategy also indicate that local inputs of crustal and anthropogenic lead play a minor role. The source-receptor relationship was confirmed by a back-trajectory cluster analysis of air-masses reaching the sampling site.

  15. Containing arsenic-enriched groundwater tracing lead isotopic compositions of common arsenical pesticides in a coastal Maine watershed

    USGS Publications Warehouse

    Ayuso, Robert A.; Foley, Nora K.; Robinson, Glipin R.; Colvin, A.S.; Lipfert, G.; Reeve, A.S.

    2006-01-01

    Arsenical pesticides and herbicides were extensively used on apple, blueberry, and potato crops in New England during the first half of the twentieth century. Lead arsenate was the most heavily used arsenical pesticide until it was officially banned. Lead arsenate, calcium arsenate, and sodium arsenate have similar Pb isotope compositions: 208Pb207Pb = 2.3839-2.4722, and 206Pb207Pb = 1.1035-1.2010. Other arsenical pesticides such as copper acetoarsenite (Paris green), methyl arsonic acid and methane arsonic acid, as well as arsanilic acid are widely variable in isotope composition. Although a complete understanding of the effects of historical use of arsenical pesticides is not available, initial studies indicate that arsenic and lead concentrations in stream sediments in New England are higher in agricultural areas that intensely used arsenical pesticides than in other areas. The Pb isotope compositions of pesticides partially overlap values of stream sediments from areas with the most extensive agricultural use. The lingering effects of arsenical pesticide use were tested in a detailed geochemical and isotopic study of soil profiles from a watershed containing arsenic-enriched ground water in coastal Maine. Acid-leach compositions of the soils represent lead adsorbed to mineral surfaces or held in soluble minerals (Fe- and Mn-hydroxides, carbonate, and some micaceous minerals), whereas residue compositions likely reflect bedrock compositions. The soil profiles contain labile Pb (acid-leach) showing a moderate range in 206Pb 207Pb (1.1870-1.2069), and 208Pb207Pb (2.4519-2.4876). Isotope values vary as a function of depth: the lowest Pb isotope ratios (e.g.,208Pb206Pb) representing labile lead are in the uppermost soil horizons. Lead contents decrease with depth in the soil profiles. Arsenic contents show no clear trend with depth. A multi-component mixing scheme that included lead from the local parent rock (Penobscot Formation), lead derived from combustion of

  16. [Speciation analysis of lead and its isotopes in fine particulate matters in Beijing by ICP-MS].

    PubMed

    Chen, Xi; Wang, Xiao-Yan; Liu, Yang; Zhang, Jing-Hua; Liu, Jing-Xiu; Yan, Lai-Lai; Wang, Jing-Yu

    2009-02-01

    Fine particulate matters (PMZ2.5) collected in Beijing during a period from September 2005 to May 2006 were studied. Sequential extraction procedures were applied to divide the total lead into three fractions, i.e. water soluble, liposoluble and insoluble lead. Lead concentrations and their isotopes in each fraction were then determined by inductively coupled plasma mass spectrometry (ICP-MS). Lead standard reference GBW 09133 was used to investigate the accuracy of lead concentration determination and SRM 981 was used to correct the mass discrimination and instrumental drift. The obtained results showed that the analytical precision of lead isotope ratios for SRM 981 of seven repeat measurements at lead concentration of 10 ng x mL(-1) came to about 0.34, 0.27 and 0.24 percent for the 206 Pb/204 Pb, 206Pb/207 Pb and 206Pb/208 Pb ratios, respectively. In Beijing, the mass concentrations for PM2.5 and lead of ambient air were 125.556 and 0.5415 microg x m(-3) respectively for winter 2005, and 201.6 and 0.475 microg x m(-3) respectively for spring 2006 on average, resembling those published results. It was indicated that the lead in the PM2.5 existed mainly in insoluble form, which accounted for 78.99%, while water soluble lead and liposoluble lead amount were 20.69% and 0.32%, respectively. The mean values of 206Pb/207Pb ratio for water soluble species and insoluble species were 1.152 6 +/- 0.009 3 and 1.219 3 +/- 0.009 1 respectively, with a significant difference (Student's test; p < 0.01) statically. By comparing 206Pb/207Pb ratios between biological specimen and ambient air samples, the 206Pb/207Pb ratios in water soluble fraction coincided very well with those in adult blood, therefore, water soluble lead but not insoluble lead in PM2.5 may be the potential source of adults blood lead in Beijing. More attention should be paid to the effect of soluble lead in fine particle matters on human health.

  17. Novel Manifestation of {alpha}-Clustering Structures: New '{alpha}+{sup 208}Pb' States in {sup 212}Po Revealed by Their Enhanced E1 Decays

    SciTech Connect

    Astier, A.; Porquet, M.-G.; Petkov, P.; Delion, D. S.; Schuck, P.

    2010-01-29

    Excited states in {sup 212}Po were populated by {alpha} transfer using the {sup 208}Pb({sup 18}O,{sup 14}C) reaction, and their deexcitation {gamma} rays were studied with the Euroball array. Several levels were found to decay by a unique E1 transition (E{sub {gamma}}<1 MeV) populating the yrast state with the same spin value. Their lifetimes were measured by the Doppler-shift attenuation method. The values, found in the range 0.1-1.4 ps, lead to very enhanced transitions, B(E1)=2x10{sup -2}-1x10{sup -3} W.u. These results are discussed in terms of an {alpha}-cluster structure which gives rise to states with non-natural-parity values, provided that the composite system cannot rotate collectively, as expected in the '{alpha}+{sup 208}Pb' case. Such states due to the oscillatory motion of the {alpha}-core distance are observed for the first time.

  18. The identification of lead ammunition as a source of lead exposure in First Nations: the use of lead isotope ratios.

    PubMed

    Tsuji, Leonard J S; Wainman, Bruce C; Martin, Ian D; Sutherland, Celine; Weber, Jean-Philippe; Dumas, Pierre; Nieboer, Evert

    2008-04-15

    The use of lead shotshell to hunt water birds has been associated with lead-contamination in game meat. However, evidence illustrating that lead shotshell is a source of lead exposure in subsistence hunting groups cannot be deemed definitive. This study seeks to determine whether lead shotshell constitutes a source of lead exposure using lead isotope ratios. We examined stable lead isotope ratios for lichens, lead shotshell and bullets, and blood from residents of Fort Albany and Kashechewan First Nations, and the City of Hamilton, Ontario, Canada. Data were analyzed using ANOVA and regression analyses. ANOVA of isotope ratios for blood revealed significant differences with respect to location, but not sex. Hamilton differed from both Kashechewan and Fort Albany; however, the First Nations did not differ from each other. ANOVA of the isotope ratios for lead ammunition and lichens revealed no significant differences between lichen groups (north and south) and for the lead ammunition sources (pellets and bullets). A plot of (206)Pb/(204)Pb and (206)Pb/(207)Pb values illustrated that lichens and lead ammunition were distinct groupings and only the 95% confidence ellipse of the First Nations group overlapped that of lead ammunition. In addition, partial correlations between blood-lead levels (adjusted for age) and isotope ratios revealed significant (p<0.05) positive correlations for (206)Pb/(204)Pb and (206)Pb/(207)Pb, and a significant negative correlation for (208)Pb/(206)Pb, as predicted if leaded ammunition were the source of lead exposure. In conclusion, lead ammunition was identified as a source of lead exposure for First Nations people; however, the isotope ratios for lead shotshell pellets and bullets were indistinguishable. Thus, lead-contaminated meat from game harvested with lead bullets may also be contributing to the lead body burden.

  19. Anthropogenic and natural lead isotopes in Fe-hydroxides and Fe-sulphates in a watershed associated with arsenic-enriched groundwater, Maine, USA

    USGS Publications Warehouse

    Ayuso, Robert A.; Foley, Nora K.

    2008-01-01

    A survey of the natural and anthropogenic sources of lead contributing to secondary minerals in sulphidic schists associated with arsenic-enriched groundwater in Coastal Maine shows that the most likely source is natural Pb, particularly from coexisting sulphide minerals. The secondary minerals also reflect notable contributions from anthropogenic Pb. The Pb isotopes establish pathways by which Pb, and by inference As, could have been transported from As-bearing minerals (arsenian pyrite, arsenopyrite, lollingite, orpiment, arsenic oxide and others), via sulphide oxidation or carbonation reactions into multiple generations of secondary minerals (goethite, hematite, jarosite, natrojarosite and others). Lead isotopic compositions of the sulphides and secondary minerals determined by thermal ionization mass spectrometry (n=53) range widely. Lead and As contents of the sulphides and secondary minerals overlap, and are generally positively correlated. Pyrite, the dominant sulphide in sulphidic schists associated with As-enriched groundwater in Coastal Maine, has values of 206Pb/204Pb from 18.186 to 18.391, 207Pb/204Pb from 15.617 to 15.657, 208Pb/204Pb from 38.052 to 38.210, 206Pb/207Pb from c. 1.1625 to 1.1760 and 208Pb/207Pb from c. 2.4276 to 2.4394. Mixtures of Fe-hydroxide and oxide minerals (predominantly goethite and hematite) and secondary Fe-sulphate minerals (jarosite, natrojarosite, rozenite and melanterite) in the sulphidic schists have overlapping but generally higher values of 206Pb/204Pb from 18.495 to 19.747 (one sample at 21.495), 207Pb/204Pb from 15.595 to 15.722 (one sample at 15.839), 208Pb/204Pb from 38.186 to 39.162,206Pb/207Pb from c.1.1860 to 1.2575 (one sample at 1.3855) and 208Pb/207Pb from c. 2.4441 to 2.4865 than the sulphides. Sulphides from Zn-Pb metal mines are somewhat less radiogenic than sulphides from the schists. Other sulphides (mostly pyrite) associated with pegmatites and granitic rocks are heterogeneous and more

  20. Source and distribution of lead in the surface sediments from the South China Sea as derived from Pb isotopes.

    PubMed

    Zhu, Laimin; Guo, Laodong; Gao, Ziyou; Yin, Guan; Lee, Ben; Wang, Fei; Xu, Jiang

    2010-11-01

    Rapid economic development in East Asian countries has inevitably resulted in environmental degradation in the surrounding seas, and concern for the environment and its protection against pollutants is increasing. Identification of sources of contaminants and evaluation of current environmental status are essential to environmental pollution management, but relatively little has been done in the South China Sea (SCS). In order to investigate the abundance, distribution, and sources of Pb within the SCS, stable Pb isotopes and their ratios were employed to assess the contamination status and to differentiate between natural and anthropogenic origins of Pb in the surface sediments. The total Pb concentrations in sediments varied from 4.18 to 58.7 mg kg(-1), with an average concentration of 23.6 ± 8.9 mg kg(-1). The observed Pb isotope ratios varied from 18.039 to 19.211 for (206)Pb/(204)Pb, 15.228 to 16.080 for (207)Pb/(204)Pb, 37.786 to 39.951 for (208)Pb/(204)Pb, 1.176 to 1.235 for (206)Pb/(207)Pb, and 2.468 to 2.521 for (208)Pb/(207)Pb. The majority of these ratios are similar to those reported for natural detrital materials. Combined with Pb enrichment factor values, our results show that Pb found within most of the SCS sediments was mainly derived from natural sources, and that there was not significant Pb pollution from anthropogenic sources before 1998. Further studies are needed to reconstruct deposition history and for trend analysis.

  1. Isotopic identification of natural vs. anthropogenic lead sources in marine sediments from the inner Ría de Vigo (NW Spain).

    PubMed

    Álvarez-Iglesias, P; Rubio, B; Millos, J

    2012-10-15

    San Simón Bay, the inner part of the Ría de Vigo (NW Spain), an area previously identified as highly polluted by Pb, was selected for the application of Pb stable isotope ratios as a fingerprinting tool in subtidal and intertidal sediment cores. Lead isotopic ratios were determined by inductively coupled plasma mass spectrometry on extracts from bulk samples after total acid digestion. Depth-wise profiles of (206)Pb/(207)Pb, (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)Pb and (208)Pb/(207)Pb ratios showed, in general, an upward decrease for both intertidal and subtidal sediments as a consequence of the anthropogenic activities over the last century, or centuries. Waste channel samples from a nearby ceramic factory showed characteristic Pb stable isotope ratios different from those typical of coal and petrol. Natural isotope ratios from non-polluted samples were established for the study area, differentiating sediments from granitic or schist-gneiss sources. A binary mixing model employed on the polluted samples allowed estimating the anthropogenic inputs to the bay. These inputs represented between 25 and 98% of Pb inputs in intertidal samples, and 9-84% in subtidal samples, their contributions varying with time. Anthropogenic sources were apportioned according to a three-source model. Coal combustion-related emissions were the main anthropogenic source Pb to the bay (60-70%) before the establishment of the ceramic factory in the area (in the 1970s) which has since constituted the main source (95-100%), followed by petrol-related emissions. The Pb inputs history for the intertidal area was determined for the 20th century, and, for the subtidal area, the 19th and 20th centuries.

  2. Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments

    NASA Astrophysics Data System (ADS)

    Hu, Ningjing; Huang, Peng

    2016-04-01

    Anthropogenic Pb input into Bohai Bay, China: Evidence from stable Pb isotopic compositions in sediments Hu Ning-jinga, Huang Pengb,, Liu Ji-huaa, a First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China b Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China To investigate the source of Pb within Bohai Bay, Pb concentrations and Pb isotopic compositions (204Pb, 206Pb, 207Pb, and 208Pb) of surface sediments in this area were determined. The Pb concentration in this bay varied widely from 6.9 to 39.2 μg/g (average: 21.8 ± 7.8 μg/g), and the Pb isotopic compositions ranged from 0.8338 to 0.8864 (average: 2.0997 ± 0.0180) for 208Pb/206Pb and from 2.0797 to 2.1531 (average: 0.8477 ± 0.0135) for 207Pb/206Pb, presenting in three distinct clusters. The Pb isotopic ratios of sediments from the northeastern (NE zone) and northwestern (NW zone) coastal areas were significantly influenced by anthropogenic sources such as coal combustion and automobile emission. In sediments from the central and southern Bohai Bay (C-S zone); however, Pb mainly originated from the Yellow River catchment, as a result of lithogenic sediment (from rock weathering) accumulation. The Pb isotopic ratios further indicate that, apart from riverine inputs, the neighboring large-scale ports and aerosols significantly contributed to the anthropogenic Pb contained in these sediments. Pb contamination in the Haihe and Luanhe river mouths as well as in the regions near ports is also suggested from anthropogenic enrichment factors. As cities and ports continue to develop around Bohai Bay, a long-term extensive sewage monitoring program is highly recommended.

  3. Monthly-resolved coral skeletal lead isotopic determination in picogram quantities by MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    Chou, Y.; Shen, C.; Lo, Y.; Chang, C.

    2011-12-01

    Pb concentrations and isotopic composition in coral skeletons have been applied to understanding annual-decadal trends of natural hydrological evolution, ocean circulation, and anthropogenic pollution. However, the low Pb contents of only 10s-100s ng/g has hindered measurements of monthly-resolved coral Pb isotopic records and limited its applications. We refined chemistry and improved instrumental methodology to develop a reliable procedure for picogram-quantity coral Pb isotopic determination (Pb-204, Pb-206, Pb-207, and Pb-208) on a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS, Thermo Electron NEPTUNE). The overall procedural blank is <20 pg. Replicate measurements made on standard NIST SRM 981 shows that our method can achieve a precision of ± 300 ppm (2σ) for Pb-207/Pb-206 and Pb-208/Pb-206 with 100s-1000s pg of Pb. Monthly-resolution Pb isotopic and concentration records of a coral Porites collected by Son Tra Island, central Vietnam (16°12'59.4", 108°1'57.1") from 1978-2004 AD have been measured. Three features are exhibited as follows: (1) The high Pb/Ca background level of 0.652 μmol/mol after 1992, 1.5 times larger than value of 0.437 μmol/mol in 1978-1992, shows an impact of economic development on hydrological change. (2) Ratios of Pb-208/Pb-207, Pb-206/Pb-207, and Pb-206/Pb-204 are relatively low in winter and high in summer, reflecting different seasonal sources. (3) Significant Pb isotopic anomalies in 1991-1992 could result from the eruption of Mt. Pinatubo on June 15, 1991. Our results indicate that monthly-resolved coral Pb isotopic and concentration can be used as proxies of seasonal climate changes, volcanic impacts and humanity activities.

  4. First proton-pair breaking in semi-magic nuclei beyond 132Sn and 208Pb: Configuration of the long-lived isomer of 217Pa

    NASA Astrophysics Data System (ADS)

    Astier, Alain; Porquet, Marie-Geneviève

    2013-01-01

    The close similarity between the shell structures in the 132Sn and 208Pb regions is a well known phenomenon. Thus, using the correspondence between the high-j orbits located above the Z=50 and Z=82 shell gaps, we discuss the evolutions of the fully aligned states with one broken proton pair in the N=82 and N=126 isotones. A long-lived isomeric state was discovered in 217Pa more than thirty years ago and, despite two other experiments giving new experimental results, the discussions on its main properties (spin, parity, configuration) remained inconclusive. Then, using the comparison with the Iπ=17/2+ isomeric state recently measured in 139La, the isomeric state of 217Pa is assigned as the fully aligned state of the (πh9/2)2(πf7/2)1 configuration.

  5. (e, e'p) reaction at true quasielastic kinematics in {sup 16}O, {sup 12}C and {sup 208}Pb at JLab

    SciTech Connect

    Herraiz, J. L.; Udias, J. M.; Weinstein, L.; Fissum, K.; Camsonne, A.; Saha, A.; Cornejo, J. C.; Aniol, K.; Urciuoli, G. M.

    2010-04-26

    The reactions {sup 16}O(e,e'p) {sup 15}N, {sup 208}Pb(e,e'p) {sup 207}Tl and {sup 12}C(e,e'p) {sup 11}B were measured in experiments E00-102 and E06-007 performed at JLab (VA, USA) at true quasielastic kinematics (x{sub B} = 1) with constant energy (omega) and momentum (q) transferred over a wide p{sub miss} range. These experiments address several open issues in nuclear structure such as the role of relativity and of long-range correlations in the description of nuclei as well as a possible dependence of the spectroscopic factors on Q{sup 2}. Preliminary experimental results and theoretical predictions from a fully relativistic DWIA model carefully averaged over the experimental acceptances are shown.

  6. Unusual potential behavior for the weakly bound nucleus 9Be in elastic scattering from 208Pb and 209Bi near the threshold

    NASA Astrophysics Data System (ADS)

    Yu, N.; Zhang, H. Q.; Jia, H. M.; Zhang, S. T.; Ruan, M.; Yang, F.; Wu, Z. D.; Xu, X. X.; Bai, C. L.

    2010-07-01

    The elastic scattering angular distributions of the weakly bound 9Be projectile from 208Pb and 209Bi have been measured for 14 beam energies near the threshold from 37 to 50 MeV. The parameters of the optical potential are extracted by means of phenomenological optical model analysis with PTOLEMY. Both of the systems show unusual potential behavior in the vicinity of the Coulomb barrier that the strength of the imaginary (absorptive) part of the potential is increasing (rather than decreasing) with decreasing energy, which is quite different from the results of some previous reports. This unusual threshold phenomenon indicates that the breakup channel is strongly coupled with the elastic channel and has obvious effects on the optical potential. The analyses also show that high precision elastic scattering angular distributions, especially those below the Coulomb barrier, are very important for extracting correct threshold behavior of the optical potential.

  7. Study of two- and multi-particle correlations in 12C+24Mg and 12C+208Pb reactions at E=35 AMeV

    NASA Astrophysics Data System (ADS)

    Quattrocchi, L.; Acosta, L.; Amorini, F.; Anzalone, A.; Auditore, L.; Berceanu, I.; Cardella, G.; Chbihi, A.; De Filippo, E.; Dell'Aquila, D.; Francalanza, L.; Gnoffo, B.; Grzeszczuk, A.; Lanzalone, G.; Lombardo, I.; Martel, I.; Minniti, T.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Veselsky, M.; Vigilante, M.

    2016-05-01

    Two and multi particle correlations from the decay of sources produced in 12C+24Mg and 12C+208Pb collisions at E=35 AMeV have been studied by using the forward part (1° < θlab < 30°) of the CHIMERA multi-detector. Correlations and invariant mass spectroscopy are used to explore simultaneous and sequential decays of resonances in light isotopes with Z˜3-6, produced in peripheral collisions via the break-up of excited quasi-projectiles. Among them we mention 5Li, 6Li, 6Be, 8Be and the astrophysically important state in 12C decaying into three alpha particles. Results and future perspectives at the INFN-LNS will be presented.

  8. Extended optical model analyses of elastic scattering and fusion cross section data for the {sup 7}Li+{sup 208}Pb system at near-Coulomb-barrier energies using a folding potential

    SciTech Connect

    So, W. Y.; Udagawa, T.; Kim, K. S.; Hong, S. W.; Kim, B. T.

    2007-08-15

    Simultaneous {chi}{sup 2} analyses previously made for elastic scattering and fusion cross section data for the {sup 6}Li+{sup 208}Pb system are extended to the {sup 7}Li+{sup 208}Pb system at near-Coulomb-barrier energies based on the extended optical model approach, in which the polarization potential is decomposed into direct reaction (DR) and fusion parts. Use is made of the double folding potential as a bare potential. It is found that the experimental elastic scattering and fusion data are well reproduced without introducing any normalization factor for the double folding potential and that both the DR and fusion parts of the polarization potential determined from the {chi}{sup 2} analyses satisfy separately the dispersion relation. Further, we find that the real part of the fusion portion of the polarization potential is attractive while that of the DR part is repulsive except at energies far below the Coulomb barrier energy. A comparison is made of the present results with those obtained from the coupled discretized continuum channels calculations and a previous study based on the conventional optical model with a double folding potential. We also compare the present results for the {sup 7}Li+{sup 208}Pb system with the analysis previously made for the {sup 6}Li+{sup 208}Pb system.

  9. Chemical signatures of the Anthropocene in the Clyde estuary, UK: sediment-hosted Pb, (207/206)Pb, total petroleum hydrocarbon, polyaromatic hydrocarbon and polychlorinated biphenyl pollution records.

    PubMed

    Vane, C H; Chenery, S R; Harrison, I; Kim, A W; Moss-Hayes, V; Jones, D G

    2011-03-13

    The sediment concentrations of total petroleum hydrocarbons (TPHs), polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), Pb and (207/206)Pb isotope ratios were measured in seven cores from the middle Clyde estuary (Scotland, UK) with an aim of tracking the late Anthropocene. Concentrations of TPHs ranged from 34 to 4386 mg kg(-1), total PAHs from 19 to 16,163 μg kg(-1) and total PCBs between less than 4.3 to 1217 μg kg(-1). Inventories, distributions and isomeric ratios of the organic pollutants were used to reconstruct pollutant histories. Pre-Industrial Revolution and modern non-polluted sediments were characterized by low TPH and PAH values as well as high relative abundance of biogenic-sourced phenanthrene and naphthalene. The increasing industrialization of the Clyde gave rise to elevated PAH concentrations and PAH isomeric ratios characteristic of both grass/wood/coal and petroleum and combustion (specifically petroleum combustion). Overall, PAHs had the longest history of any of the organic contaminants. Increasing TPH concentrations and a concomitant decline in PAHs mirrored the lessening of coal use and increasing reliance on petroleum fuels from about the 1950s. Thereafter, declining hydrocarbon pollution was followed by the onset (1950s), peak (1965-1977) and decline (post-1980s) in total PCB concentrations. Lead concentrations ranged from 6 to 631 mg kg(-1), while (207/206)Pb isotope ratios spanned 0.838-0.876, indicative of various proportions of 'background', British ore/coal and Broken Hill type petrol/industrial lead. A chronology was established using published Pb isotope data for aerosol-derived Pb and applied to the cores.

  10. Pb isotopic constraints on the formation of the Dikulushi Cu-Pb-Zn-Ag mineralisation, Kundelungu Plateau (Democratic Republic of Congo)

    NASA Astrophysics Data System (ADS)

    Haest, Maarten; Schneider, Jens; Cloquet, Christophe; Latruwe, Kris; Vanhaecke, Frank; Muchez, Philippe

    2010-04-01

    Base metal-Ag mineralisation at Dikulushi and in other deposits on the Kundelungu Plateau (Democratic Republic of Congo) developed during two episodes. Subeconomic Cu-Pb-Zn-Fe polysulphide ores were generated during the Lufilian Orogeny (c. 520 Ma ago) in a set of E-W- and NE-SW-oriented faults. Their lead has a relatively unradiogenic and internally inhomogeneous isotopic composition (206Pb/204Pb = 18.07-18.49), most likely generated by mixing of Pb from isotopically heterogeneous clastic sources. These sulphides were remobilised and enriched after the Lufilian Orogeny, along reactivated and newly formed NE-SW-oriented faults into a chalcocite-dominated Cu-Ag mineralisation of high economic interest. The chalcocite samples contain only trace amounts of lead and show mostly radiogenic Pb isotope signatures that fall along a linear trend in the 207Pb/204Pb vs. 206Pb/204Pb diagram (206Pb/204Pb = 18.66-23.65; 207Pb/204Pb = 15.72-16.02). These anomalous characteristics reflect a two-stage evolution involving admixture of both radiogenic lead and uranium during a young fluid event possibly c. 100 Ma ago. The Pb isotope systematics of local host rocks to mineralisation also indicate some comparable young disturbance of their U-Th-Pb systems, related to the same event. They could have provided Pb with sufficiently radiogenic compositions that was added to less radiogenic Pb remobilised from precursor Cu-Pb-Zn-Fe polysulphides, whereas the U most likely originated from external sources. Local metal sources are also suggested by the 208Pb/204Pb-206Pb/204Pb systematics of combined ore and rock lead, which indicate a pronounced and diversified lithological control of the immediate host rocks on the chalcocite-dominated Cu-Ag ores. The Pb isotope systematics of polysulphide mineralisation on the Kundelungu Plateau clearly record a diachronous evolution.

  11. U-Th-Pb isotopic constraints on the oxidation age of 3.4 Ga basalts from Marble Bar, Pilbara Craton, NW Australia

    NASA Astrophysics Data System (ADS)

    Li, W.; Johnson, C.; Beard, B. L.

    2011-12-01

    Determining the evolution of Earth's early atmosphere is critical to understanding the geologic history of the Earth, and one of the key aspects of atmospheric evolution has been the development of free oxygen. A common model involves an increase in free O2 between 2.4 and 2.2 Ga, termed the Great Oxidation Event (GOE). Although there is growing evidence for free O2 in the atmosphere or photic zone of the oceans several hundred m.y. before the GOE, hematite alteration products in 3.4 Ga basalts from the Marble Bar area of the Pilbara Craton, NW Australia have been used to infer the presence of an O2-bearing atmosphere even earlier. These Fe-oxides have not been directly dated, however, raising the possibility that they formed at a later time. Here we report new U-Th-Pb isotopic results of Apex Basalt samples from the ABDP-1 drill core at Marble Bar that allows determination of the age of the iron oxides. The basalt samples that have been variously oxidized have highly variable Pb and U concentrations, and scatter about a 207Pb/204Pb-206Pb/204Pb array that could be interpreted as an Archean age. U/Pb ratios are positively correlated with Fe(III)/ Fetotal ratios, indicating that U enrichment accompanied oxidation. In contrast, Th is positively correlated with Zr, suggesting Th has been immobile. The samples do not form isochrons on 238U/204Pb-206Pb/204Pb, 235U/204Pb-207Pb/204Pb, or 232Th/204Pb-208Pb/204Pb diagrams, indicating post-formation U and Pb addition. The 207Pb/204Pb-206Pb/204Pb array, therefore, is a mixing line and not an isochron. The U-Pb isotope data mandate that the age for U addition for three basalt samples must be younger than 2.5 Ga, even in the most conservative estimate. A more stringent model, which compares the measured U/Th ratios with those required to produce the 208Pb/204Pb-206Pb/204Pb variations, indicates that U enrichment most likely occurred in the last 200 m.y. This relatively young age for U enrichment is consistent with the deep

  12. Fission and binary fragmentation reactions in {sup 80}Se+{sup 208}Pb and {sup 80}Se+{sup 232}Th systems

    SciTech Connect

    Thomas, R. G.; Saxena, A.; Sahu, P. K.; Kailas, S.; Kapoor, S. S.; Choudhury, R. K.; Govil, I. M.; Barbui, M.; Cinausero, M.; Prete, G.; Rizzi, V.; Fabris, D.; Lunardon, M.; Moretto, S.; Viesti, G.; Nebbia, G.; Pesente, S.; Dalena, B.; D'Erasmo, G.; Fiore, E. M.

    2007-02-15

    Fission and binary fragmentation of the excited nuclear systems of Z=116 and 124 were investigated using the reactions induced by {sup 80}Se beams on {sup 208}Pb and {sup 232}Th targets at bombarding energies ranging from 470 to 630 MeV. The mass and kinetic energy of the binary reaction products were reconstructed by measuring their velocities by the time-of-flight method and the angles of emission using multiwire proportional chambers. Total neutron multiplicities were measured in coincidence with the fragments, using an array of neutron detectors. The fragment mass-energy correlation was studied for the two systems. The average total kinetic energy (TKE) of fragments for the {sup 80}Se+{sup 208}Pb system agrees with earlier measurements and with Viola's systematics in the mass symmetric region for compound nucleus fission, whereas for the {sup 80}Se+{sup 232}Th system, the TKE values are significantly lower. This is also consistent with higher values of total neutron multiplicities observed for the case of {sup 80}Se+{sup 232}Th at comparable available energies. From an extrapolation of the measured total neutron multiplicities for the mass symmetric region to zero compound nucleus excitation energy, the average number of prompt neutrons expected to be emitted in the spontaneous fission of the superheavy Z=116 has been estimated to be {nu}{sub tot}{sup sf}=10{+-}2, which is consistent with the value derived for the same compound nucleus populated in the {sup 56}Fe+{sup 232}Th reaction in an earlier work. In the case of the {sup 80}Se+{sup 232}Th system, similar analysis was carried out by taking the average TKE from Viola's systematics for estimating the available energy for particle emission corresponding to compound nucleus fission. In this way, by extrapolating the observed neutron multiplicities to zero compound nucleus excitation energy, a value of {nu}{sub tot}{sup sf}=15{+-}2 was obtained for the spontaneous fission of the superheavy Z=124 nucleus. The

  13. Lead (Pb) fluxes and Pb isotopic compositions from Masaya Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Vallelonga, P.; Mather, T. A.

    We report Pb concentrations and isotopic compositions measured in plume aerosol and Pele's hair (lava) samples collected from Masaya volcano, Nicaragua, to provide the first data pertaining to Pb emissions from the Central American volcanic arc. Lead isotopic compositions, determined by Thermal Ionisation Mass Spectrometry, in the Pele's hair samples were found to be 206Pb/ 207Pb˜1.196, 208Pb/ 207Pb˜2.46 and 206Pb/ 204Pb˜18.6. Mean Pb fluxes from Masaya were calculated to be 1.0 ton Pb yr -1 with a mean plume Pb/S (gas) ratio of 1.3×10 -5. Also, it was found that the majority of Pb emitted was present in the fine aerosol (<2.5 μm diameter) fraction but that the percentage of Pb in the fine aerosol fraction decreased from 96% in the dry daytime plume to 61% in the condensed night-time plume. The contribution from the filter blank was usually a substantial fraction of the total amount of Pb measured, requiring the data to be corrected for blank contributions using Pb isotopic systematics.

  14. K-Ar ages and Pb, Sr isotopic characteristics of Cenozoic volcanic rocks in Shandong Province, China

    USGS Publications Warehouse

    Daogong, C.; Zicheng, P.; Lanphere, M.A.; Zartman, R.E.

    1985-01-01

    28 samples of Cenozoic volcanic rocks collected from Shandong Province have been dated by K-Ar method. They are mainly Neogene with an age range of 4-19 m. y. The basalts from Linqu and Yishui in west Shandong Province are Miocene and those from Penglai and Qixia in east Shandong Province are Miocene and Pliocene in age. The basalts from Wudi in north Shandong Province are Middle-Early Pleistocene in age. In each area the duration of volcanic eruption was estimated at about 2-3 m. y. Pb and Sr isotopic compositions and U, Th, Pb, Rb, Sr, and major elements in most of the samples were determined. The isotopic compositions are:206Pb/204Pb-16.92-18.48,207Pb/204Pb-15.30-15.59,208Pb/204Pb-37.83-38.54, and (87Sr/86Sr)i-0.70327-0.70632. There are some positive or negative linear correlations between206Pb/204Pb and207Pb/204Pb, Pb isotopes and Pb content, Pb isotopes and Sr isotopes, and Sr isotopes and other elements. The basaltic rocks from east and west Shandong Province have somewhat differences in isotopic composition and element content. The basalts probably are products of multi-stage evolution of the mantle. They have preserved the primary features of the source, although they were influenced, to some extent, by the contamination of crustal materials. ?? 1985 Institute of Geochemistry, Chinese Academy of Sciences.

  15. Identification of trace metal pollution in urban dust from kindergartens using magnetic, geochemical and lead isotopic analyses

    NASA Astrophysics Data System (ADS)

    Zhu, Zongmin; Sun, Guangyi; Bi, Xiangyang; Li, Zhonggen; Yu, Genhua

    2013-10-01

    In the present study, magnetic measurements were combined with geochemical analysis and stable Pb isotopic ratios to reveal the distribution and origination of trace metal pollutants in kindergarten dusts from a typical urban environment of Wuhan, central China. The geoaccumulation index (Igeo) of magnetic properties was more prominent than those of individual metals. The magnetic susceptibility (MS) and trace metals (Zn, Pb, and Cu) in this study together with published results from other Chinese cities formed a liner relationship, suggesting that metal contaminants in Chinese urban areas had similar MS to metal ratios, which could be used as an indicator for identification of pollution sources between Chinese cities and the other Asian cities. Stable Pb isotopic ratios (1.1125-1.1734 for 206Pb/207Pb and 2.4457-2.4679 for 208Pb/207Pb) in the urban dusts from Wuhan were characterized by higher 208Pb component in comparison with those from other Chinese cities. This result combined with principal component analysis (PCA) indicated that metal pollutants in the dusts were derived from industrial activities and coal combustion, whereas the traffic emissions were no longer a predominant pollution source in urban environment. Our study demonstrated that environmental magnetic methods could not only reveal the overall situation of trace metal contamination, but also prove evidence in the identification of pollution sources.

  16. The Condor seamount at Mid-Atlantic Ridge as a supplementary source of trace and rare earth elements to the sediments

    NASA Astrophysics Data System (ADS)

    Caetano, Miguel; Vale, Carlos; Anes, Bárbara; Raimundo, Joana; Drago, Teresa; Schimdt, Sabine; Nogueira, Marta; Oliveira, Anabela; Prego, Ricardo

    2013-12-01

    The Condor Seamount rises from seabed to 180m water depth, being located 10 nautical miles southwest of the island of Faial, Azores Archipelago at the Mid-Atlantic Ridge (MAR). The vertical distribution of major, minor, trace and rare earth elements (REE) and Pb isotopes was studied in four sediment cores: one from the top of the Condor Seamount (200m, MC9), two from the seamount base (1400m, MC2 and MC4), and one from a deep area (1900m, MC8). Sediments from the top of the Condor were composed by coarser particles being the fine fraction lower than 1%. Conversely the other sediments were constituted by 51-92% of fine particles (<63μm). Individual fragments of volcanic material (>2mm) were found at several depths of the cores sampled at the base of the seamount. The core collected in the top of the Condor showed higher carbonate content (76-86%) compared with the other cores (41-64%). The chemical compositions of MC2 and MC4 point to an enhancement of V, Cr, Co, Ni and Fe concentrations. Lower concentrations in MC8 hypothesis that Condor seamount constitutes a supplementary source of trace elements. The most plausible explanation for the enhancement found in sediments of the seamount base is the weathering of slopes with volcanic activities, which supply particles with higher element concentrations than pelagic sediments. This hypothesis is corroborated by REE data, showing increased chondrite normalized ratios in MC2 and MC4. Moreover, the REE pattern found in those cores was comparable to that existing in volcanic material with Light REE enrichment in comparison to Heavy REE. These results indicate a substantial contribution of particles derived from volcanic activities to sediments settled in the vicinity of the Condor Seamount. It is argued the potential use of REE in sediments from this region as tracers of volcanic activities. Depth profiles of 206Pb/207Pb and 206Pb/208Pb showed lower ratios in the first 8cm sediment layers, reflecting atmospheric input of

  17. Natural radionuclide mobility and its influence on U-Th-Pb dating of secondary minerals from the unsaturated zone at Yucca Mountain, Nevada

    USGS Publications Warehouse

    Neymark, L.A.; Amelin, Y.V.

    2008-01-01

    Extreme U and Pb isotope variations produced by disequilibrium in decay chains of 238U and 232Th are found in calcite, opal/chalcedony, and Mn-oxides occurring as secondary mineral coatings in the unsaturated zone at Yucca Mountain, Nevada. These very slowly growing minerals (mm my-1) contain excess 206Pb and 208Pb formed from excesses of intermediate daughter isotopes and cannot be used as reliable 206Pb/238U geochronometers. The presence of excess intermediate daughter isotopes does not appreciably affect 207Pb/235U ages of U-enriched opal/chalcedony, which are interpreted as mineral formation ages. Opal and calcite from outer (younger) portions of coatings have 230Th/U ages from 94.6 ?? 3.7 to 361.3 ?? 9.8 ka and initial 234U/238U activity ratios (AR) from 4.351 ?? 0.070 to 7.02 ?? 0.12, which indicate 234U enrichment from percolating water. Present-day 234U/238U AR is ???1 in opal/chalcedony from older portions of the coatings. The 207Pb/235U ages of opal/chalcedony samples range from 0.1329 ?? 0.0080 to 9.10 ?? 0.21 Ma, increase with microstratigraphic depth, and define slow long-term average growth rates of about 1.2-2.0 mm my-1, in good agreement with previous results. Measured 234U/238U AR in Mn-oxides, which pre-date the oldest calcite and opal/chalcedony, range from 0.939 ?? 0.006 to 2.091 ?? 0.006 and are >1 in most samples. The range of 87Sr/86Sr ratios (0.71156-0.71280) in Mn-oxides overlaps that in the late calcite. These data indicate that Mn-oxides exchange U and Sr with percolating water and cannot be used as a reliable dating tool. In the U-poor calcite samples, measured 206Pb/207Pb ratios have a wide range, do not correlate with Ba concentration as would be expected if excess Ra was present, and reach a value of about 1400, the highest ever reported for natural Pb. Calcite intergrown with opal contains excesses of both 206Pb and 207Pb derived from Rn diffusion and from direct ??-recoil from U-rich opal. Calcite from coatings devoid of opal

  18. Excitation function for the production of {sup 262}Bh (Z=107) in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n)

    SciTech Connect

    Folden, C.M. III; Nelson, S.L.; Duellmann, Ch.E.; Schwantes, J.M.; Zielinski, P.M.; Nitsche, H.; Hoffman, D.C.; Sudowe, R.; Gregorich, K.E.

    2006-01-15

    The excitation function for production of {sup 262}Bh in the odd-Z-projectile reaction {sup 208}Pb({sup 55}Mn, n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from {sup 262}Bh and 2 decay chains originating from {sup 261}Bh were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540{sub -150}{sup +180} pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than five times larger than that expected based on previously reported results for production of {sup 262}Bh in the analogous even-Z-projectile reaction {sup 209}Bi({sup 54}Cr, n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the optimum energy rule proposed by SwiaPtecki, Siwek-Wilczynska, and Wilczynski.

  19. Excitation function for the production of 262Bh (Z = 107) in theodd-Z projectile reaction 208Pb(55Mn, n)

    SciTech Connect

    Folden III, C.M.; Nelson, S.L.; Dullmann, Ch.E.; Schwantes, J.M.; Sudowe, R.; Zielinski, P.M.; Gregorich, K.E.; Nitsche, H.; Hoffman, D.C.

    2005-05-16

    The excitation function for production of 262Bh in the odd-Z-projectile reaction 208Pb(55Mn,n) has been measured at three projectile energies using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. In total, 33 decay chains originating from 262Bh and 2 decay chains originating from 261Bh were observed. The measured decay properties are in good agreement with previous reports. The maximum cross section of 540 +180 - 150 pb is observed at a lab-frame center-of-target energy of 264.0 MeV and is more than fives times larger than that expected based on previously reported results for production of 262Bh in the analogous even-Z-projectile reaction 209Bi(54Cr,n). Our results indicate that the optimum beam energy in one-neutron-out heavy-ion fusion reactions can be estimated simply using the ''Optimum Energy Rule'' proposed by Swiatecki, Siwek-Wilczynska, and Wilczynski.

  20. Neutron and light-charged-particle productions in proton-induced reactions on 208Pb at 62.9 MeV

    NASA Astrophysics Data System (ADS)

    Guertin, A.; Marie, N.; Auduc, S.; Blideanu, V.; Delbar, Th.; Eudes, P.; Foucher, Y.; Haddad, F.; Kirchner, T.; Le Brun, Ch.; Lebrun, C.; Lecolley, F. R.; Lecolley, J. F.; Ledoux, X.; Lefèbvres, F.; Lefort, T.; Louvel, M.; Ninane, A.; Patin, Y.; Pras, Ph.; Rivière, G.; Varignon, C.

    2005-01-01

    Neutrons and light charged particles produced in 62.9MeV proton-induced reactions on 208Pb were measured during a single experiment performed at the CYCLONE facility in Louvain-la-Neuve (Belgium). Two independent experimental set-ups were used to extract double differential cross-sections for neutrons, protons, deuterons, tritons, 3He and alpha-particles. Charged particles were detected using a set of Si- Si- CsI telescopes from 25° to 155°, by step of 10 degrees. Neutrons were measured using shielded DeMoN counters, liquid NE213 scintillators, at 24°, 35°, 55°, 80° and 120°. These data allowed the determination of angle differential, energy differential and total production cross-sections. A comparison with theoretical calculations (MCNPX, FLUKA and TALYS) has been performed. It shows that the neutron and proton production rates are well predicted by MCNPX, using the INCL4 option. All the other codes underestimate the neutron production whereas they overestimate the proton one. For composite particles, which represent 17% of the charged particle total reaction cross-section, neither the shape nor the amplitude of the cross-sections are correctly predicted by the models.

  1. The fusion fission and quasi-fission processes in the reaction 48Ca + 208Pb at energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Prokhorova, E. V.; Bogachev, A. A.; Itkis, M. G.; Itkis, I. M.; Knyazheva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Pashkevich, V. V.; Rusanov, A. Ya.

    2008-04-01

    Mass-energy distributions (MEDs) and capture-fission cross sections have been measured in the reaction 48Ca + 208Pb → 256No at the energies E=206-242 MeV using a double-arm time-of-flight spectrometer CORSET. It has been observed that MED of the fragments consists of two parts, namely, the classical fusion-fission process corresponding to the symmetric fission of 256No and quasi-fission "shoulders" corresponding to the light fragment masses ˜60-90 u and complimentary heavy fragment masses. The quasi-fission "shoulders" have a higher total kinetic energy (TKE) as compared with that expected for the classical fission. A mathematical formalism was employed for the MEDs fragment decomposition into fusion-fission and quasi-fission components. In the fusion-fission process a high-energy Super-Short mode has been discovered for the masses M=130-135 u and the TKE of ≈233 MeV.

  2. Precise geochronology of phoscorites and carbonatites: - The critical role of U-series disequilibrium in age interpretations

    NASA Astrophysics Data System (ADS)

    Amelin, Yuri; Zaitsev, Anatoly N.

    2002-07-01

    We present the results of a comparative study of several geochronometer minerals (baddeleyite, zircon, apatite, phlogopite and tetraferriphlogopite) and isotopic systems (U-Pb, Th-Pb and Rb-Sr) from phoscorites (magnetite-forsterite-apatite-calcite rocks) and carbonatites of the Kovdor ultramafic-alkaline-carbonatite massif, Kola Peninsula, Russia. Uranium, thorium and their decay products are extremely fractionated by minerals that crystallise from carbonatite and phoscorite magma. We obtain high-precision ages from different chronometers, compare their accuracy, and evaluate the role of geochronological pitfalls of initial radioactive disequilibrium, differential migration of radiogenic isotopes, and inaccurate decay constants. Apatite yielded concordant U-Th-Pb ages between 376 and 380 Ma. The accuracy of the apatite 238U- 206Pb ages is, however, compromised by uncertainty in the amount of radiogenic 206Pb produced from initial excess 230Th. The 235U- 207Pb ages are relatively imprecise due to large common Pb correction and the uncertainty in the initial Pb isotopic composition. The Th-Pb system yields a more precise age of 376.4 ± 0.6 Ma. Zircon from two carbonatite samples is characterised by moderate to low U contents, high Th contents, and very high Th/U ratios up to 9000. The 206Pb*/ 238U systems in the zircon are strongly affected by the presence of excess 206Pb*, produced by decay of initial 230Th. The 208Pb*/ 232Th ages of zircon from both carbonatite samples are uniform and yield a weighted average of 377.52 ± 0.94 Ma. Baddeleyite U-Pb analyses are 3 to 6% normally discordant and have variable 207Pb*/ 206Pb* apparent ages. Eleven alteration-free baddeleyite fractions from three samples with no evidence for Pb loss yield uniform 206Pb*/ 238U ages with a weighted average of 378.54±0.23 Ma (378.64 Ma after correction for initial 230Th deficiency), which we consider the best estimate for age of the phoscorite-carbonatite body of the Kovdor massif. The

  3. Spectroscopic Constants of the Known Electronic States of Lead Monofluoride

    SciTech Connect

    McRaven, C.P.; Sivakumar, P.; Shafer-Ray, N.E.; Hall, G.E.; Sears, T.J.

    2010-08-01

    Based on measurements made by mass-resolved 1 + 1{prime} + 1{double_prime} resonance-enhanced multiphoton ionization spectroscopy, we have determined new molecular constants describing the rotational and fine structure levels of the B, D, E, and F states of the most abundant isotopic variant {sup 208}Pb{sup 19}F, and we summarize the spectroscopic constants for all the know electronic states of the radical. Many spectroscopic constants for the isotopologues {sup 206}Pb{sup 19}F and {sup 207}Pb{sup 19}F have also been determined. The symmetry of the D-state is found to be {sup 2}{pi}{sub 1/2}, and the F-state is found to be an {Omega} = 3/2 state.

  4. Determination of the geographic origin of rice by chemometrics with strontium and lead isotope ratios and multielement concentrations.

    PubMed

    Ariyama, Kaoru; Shinozaki, Miyuki; Kawasaki, Akira

    2012-02-22

    The objective of this study was to develop a technique for determining the country of origin of rice in the Japanese market. The rice samples included a total of 350 products grown in Japan (n = 200), the United States (n = 50), China (n = 50), and Thailand (n = 50). In this study, (87)Sr/(86)Sr and Pb isotope ((204)Pb, (206)Pb, (207)Pb, and (208)Pb) ratios and multielement concentrations (Al, Fe, Co, Ni, Cu, Rb, Sr, and Ba) were determined by high-resolution inductively coupled plasma mass spectrometry. By combining three chemometric techniques based on different principles and determination criteria, the countries of origin of rice were determined. The predictions made by 10-fold cross-validation were around 97% accurate. The presented method demonstrated the effectiveness of determining the geographic origin of an agricultural product by combining several chemometric techniques using heavy element isotope ratios and multielement concentrations.

  5. Allanite from the El Muerto Pegmatite, Oaxaca, Mexico: A Potential New Standard for 232Th-208Pb Dating by LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Price, J.; Crowley, J. L.; Solari, L.; Prol-Ledesma, R.

    2012-12-01

    Allanite dating may be important to studies addressing tectonomagmatic evolution, provenance of monocyclic sediment, and mineral weathering. Obtaining accurate allanite ages by SIMS has been challenging and time-consuming due to the mineral's extreme chemical variability which often prevents finding adequately matrix-matched standards. Isotopic measurements by LA-ICP-MS minimize the need for standards of nearly identical composition to the unknown allanite being analyzed, and it is done relatively rapidly. Dating by LA-ICP-MS requires high quality standards for isotopic fractionation corrections. However, readily accessible and well characterized allanite standards are scarce. We investigated gemstone allanite from the El Muerto pegmatite, Oaxaca, Mexico, as a potential new geochronology standard for 232Th-208Pb allanite dating by LA-ICP-MS. Compositional homogeneity was thoroughly investigated by scanning and backscatter electron microscopy, cathodoluminescence, quantitative and qualitative energy dispersive x-ray spectroscopy, electron microprobe, and LA-ICP-MS. The possibility of metamictization was investigated by extensive X-ray diffraction analyses. The El Muerto allanite was U-Pb dated by ID-TIMS, with common Pb ratios determined from cogenetic K-feldspar by ID-TIMS and LA-MC-ICP-MS. Future work includes Th-Pb dating by ID-TIMS. The samples investigated are homogeneous with respect to major and trace elements. Major element compositional results are generally in agreement with published values, and no metamictization was identified despite the allanite being nearly 1 Ga. The only limitation of the El Muerto allanite is that it contains small, generally <100 μm, scarce inclusions of quartz, calciothorite, albite, calcite, and biotite. However, these grains are easily recognized and avoided during LA-ICP-MS analyses. Based on these results, the El Muerto allanite has the potential to serve as a standard for LA-ICP-MS dating.

  6. Lead isotopes and trace metal ratios of aerosols as tracers of Pb pollution sources in Kanpur, India

    NASA Astrophysics Data System (ADS)

    Sen, Indra; Bizimis, Michael; Tripathi, Sachchida; Paul, Debajyoti; Tyagi, Swati; Sengupta, Deep

    2015-04-01

    The anthropogenic flux of Pb in the Earth's surface is almost an order of magnitude higher than its corresponding natural flux [1]. Identifying the sources and pathways of anthropogenic Pb in environment is important because Pb toxicity is known to have adverse effects on human health. Pb pollution sources for America, Europe, and China are well documented. However, sources of atmospheric Pb are unknown in India, particularly after leaded gasoline was phased out in 2000. India has a developing economy with a rapidly emerging automobile and high temperature industry, and anthropogenic Pb emission is expected to rise in the next decade. In this study, we report on the Pb- isotope compositions and trace metal ratios of airborne particulates collected in Kanpur, an industrial city in northern India. The Pb concentration in the airborne particulate matter varies between 14-216 ng/m3, while the other heavy metals vary by factor of 10 or less, e.g. Cd=0.3-3 ng/m3, As=0.4-3.5 ng/m3, Zn=36-161 ng/m3, and Cu=3-22 ng/m3. The 206Pb/207Pb, 208Pb/206Pb, and 208Pb/207Pb vary between 1.112 - 1.129, 2.123-2.141, and 2.409-2.424 respectively, and are highly correlated with each other (R2>0.9). Pb isotopes and trace metal data reveals that coal combustion is the major source of anthropogenic Pb in the atmosphere, with limited contribution from mining and smelting processes. We further conclude that combination of Pb isotope ratios and V/Pb ratios are powerful tracers for Pb source apportionment studies, which is otherwise difficult to differentiate based only on Pb systematics [1] Sen and Peucker-Ehrenbrink (2012), Environ. Sci. Technol.(46), 8601-8609

  7. Spatial and temporal evolution of lead isotope ratios in the North Atlantic Ocean between 1981 and 1989

    NASA Astrophysics Data System (ADS)

    Weiss, Dominik; Boyle, Edward A.; Wu, Jingfeng; Chavagnac, ValéRie; Michel, Anna; Reuer, Matthew K.

    2003-10-01

    /tropical surface water exchanges. Triple-isotope plots (206Pb, 207Pb, and 208Pb) suggest that most of the lead can be accounted for by wet aerosol deposition derived from the adjacent landmasses of America to the west (transported via the North American Westerlies) and from Europe to the east (transported via the European Easterlies) and probably by some advected surface waters from the Sargasso Sea. The 1989 triple-isotope plot suggests, however, a third lead source in the subtropical western North Atlantic, possibly leaded gasoline from Mexico. Gasoline lead emission patterns as well as atmospheric lead isotope signatures confirm that gasoline was the main pollutant source in the early 1980s but suggest that contributions from high-temperature industrial processes (coal combustion, steel manufacture, waste incineration) have been increasing in the late 1980s. From isotopic mass balance estimates, lead inputs to the 1980s North Atlantic were dominated by North American sources (>53%). These elemental and isotopic results demonstrate the strongly variable isotopic and elemental signatures of North American and European lead throughout the North Atlantic Ocean, frequently dominated by high 206Pb/207Pb and [Pb] North American signatures throughout the subtropical North Atlantic gyre.

  8. Plume-Lithosphere Interaction beneath the Snake River Plain, Idaho: Constraints from Pb, Sr, Nd, and Hf Isotopes

    NASA Astrophysics Data System (ADS)

    Jean, M. M.; Hanan, B. B.; Shervais, J. W.

    2011-12-01

    The Yellowstone-Snake River Plain (YSRP) volcanic province links 17 million years of volcanic activity that extends from the Owyhee Plateau in western Idaho/eastern Oregon to its current terminus underlying the Yellowstone Plateau. This investigation presents new Strontium, Neodymium, Lead, and Hafnium isotopic compositions of 25 basalts that represent four distinct areas of the YSRP (i.e., eastern province, central province, western province, Owyhee Plateau), which transect the ancient cratonic boundary of North America. The purpose of this study is to test and refine models for plume-lithosphere interaction and determines the mantle origin for YSRP basalts. New results shows: (1) low-K tholeiites from the eastern, central, and western SRP have ɛNd (-2 to -5.5), 87Sr/86Sr (0.7060-0.7071) and similar Pb-isotopes [206Pb/204Pb (17.8-18.6), 207Pb/204Pb (15.5-15.66), 208Pb/204Pb (38.4-39.1)]; (2) central SRP tholeiites are enriched in 208Pb/204Pb (~38.5-38.9), relative to eastern SRP basalts and define a 208Pb/204Pb trend, intermediate between the eastern SRP and Craters of the Moon lavas; (3) western SRP high-K basalts are depleted in ɛNd (> -1) and 87Sr/86Sr (0.7050-0.7057), relative to low-K tholeiites, and plot closer to "bulk silicate earth," but are enriched in 206Pb/204Pb (18.66-18.71), and have 207Pb/204Pb (15.62-15.65) and 208Pb/204Pb (39.1-39.2) isotope ratios similar to high-K basalts of Smith Prairie (Boise River Group 2); (4) Silver City basalt (>16.6 Ma) overlaps in Pb-isotope space with Imnaha basalt compositions (Columbia River Basalt Group); (5) new 177Hf/176Hf isotopic data lie above and parallel to the Mantle array in Nd and Hf isotope space and define a linear trend between Leucite Hills lavas and OIB basalts (i.e., Steens and Hawaii); (6) these basalts follow a systematic geographic pattern: eastern and central plain low-K tholeiites have low ɛNd (-3 to -5) and intermediate 206Pb/204Pb (~17.7-18.5), while western plain low-K tholeiites are

  9. Lead Isotopes from the Upper Mississippi Valley District: A Regional Perspective

    USGS Publications Warehouse

    Millen, Timothy M.; Zartman, Robert E.; Heyl, Allen Van

    1995-01-01

    New lead isotopic data on galena from within and peripheral to the Upper Mississippi Valley lead-zinc district make it possible, by extending coverage to outlying locations, to trace the pathway traversed by the mineralizing fluids beyond the boundary of the main district. All but one of the samples exhibit elevated ratios of the radiogenic isotopes typical of the Upper Mississippi Valley ore deposits; 206PbP04Pb ranges from 19.38 to 24.46, 207PbP04Pb ranges from 15.73 to 16.24, and 208PbP04Pb ranges from 39.24 to 43.69. Galena from the Pints quarry near Waterloo, Iowa, has distinctly lower values of these ratios and may not be related paragenetically to the other samples. Otherwise, the lowest ratios are for samples in the southern part of the region in north-central Illinois, and the highest ratios are for samples to the northeast of the main district in the vicinity of Madison, Wisconsin. Thus, an isotopic pattern rather similar to that observed originally by Heyl and others (1966) prevails regionally, although the predominant fluid flow is now believed to have emanated from the Illinois Basin rather than from the Forest City Basin. Metal-bearing brines being driven northward out of the Illinois Basin probably played the key role in mineralization of the Upper Mississippi Valley district. Both the new and the previously reported lead ratios for the Upper Mississippi Valley district are plotted on 207PbP04Pb and Pb208/pb204Pb versus 206PbP04Pb diagrams, which permit their comparison and the calculation of refined slopes for the expanded data set. A two-stage model age for the time of mineralization can be determined from the 207PbP04Pb_Pb206/Pb204 slope, provided that the source age of the lead is known. With our limited know ledge of this source age, the time of mineralization cannot be tightly constrained but is permissive of a Permian or younger lateral secretion event, as suggested by other geochronological results.

  10. Temporal trends of pollution Pb and other metals in east-central Baffin Island inferred from lake sediment geochemistry.

    PubMed

    Michelutti, Neal; Simonetti, Antonio; Briner, Jason P; Funder, Svend; Creaser, Robert A; Wolfe, Alexander P

    2009-10-15

    Concentrations and stable isotope ratios of lead (Pb) from lake sediments were used to quantify temporal patterns of anthropogenic Pb pollution in the Clyde River region of Baffin Island, Arctic Canada. Surface sediments from eight lakes on eastern Baffin Island and one from northern-most Greenland, spanning a gradient of 20 degrees latitude, showed great variability with respect to Pb concentration and stable isotopic Pb ratios, with little apparent latitudinal trend. To constrain the temporal evolution of regional Pb pollution, a well-dated core from one of the sites, Lake CF8 on east-central Baffin Island, was analyzed geochemically at high stratigraphic resolution. A pronounced decrease in the (206)Pb/(207)Pb ratio occurs in sediments deposited between 1923 and the mid-1970s, likely reflecting alkyl-Pb additives derived from the combustion of fossil fuels at a global scale. A two-component mixing model indicates that 17-26% of the Pb in the labile fraction of sediments deposited in Lake CF8 between 2001 and 2005 is from anthropogenic input. A Pb-Pb co-isotopic plot ((206)Pb/(207)Pb vs.(208)Pb/(206)Pb ratios) of the Lake CF8 time series data indicates multiple possible sources of industrial Pb pollution. Despite widespread reductions in industrial Pb emissions since the 1970s, there is no evidence for attendant reductions of pollution Pb at Lake CF8. Enhanced scavenging from increased primary production as well as changing precipitation rates as climate warms may represent important factors that modulate Pb deposition to Lake CF8, and Arctic lakes elsewhere. PMID:19665172

  11. Accumulation and quantitative estimates of airborne lead for a wild plant (Aster subulatus).

    PubMed

    Hu, Xin; Zhang, Yun; Luo, Jun; Xie, Mingjie; Wang, Tijian; Lian, Hongzhen

    2011-03-01

    Foliar uptake of airborne lead is one of the pathways for Pb accumulation in plant organs. However, the approximate contributions of airborne Pb to plant organs are still unclear. In the present study, aerosols (nine-stage size-segregated aerosols and total suspended particulates), a wild plant species (Aster subulatus) and the corresponding soils were collected and Pb contents and isotopic ratios in these samples were analyzed. Average concentration of Pb was 96.5 ± 63.5 ng m(-3) in total suspended particulates (TSP) and 20.4 ± 5.5 ng m(-3) in the fine fractions of size-segregated aerosols (SSA) (<2.1 μm), higher than that in the coarser fractions (>2.1 μm) (6.38 ± 3.71 ng m(-3)). Enrichment factors show that aerosols and soils suffered from anthropogenic inputs and the fine fractions of the size-segregated aerosols enriched more Pb than the coarse fractions. The order of Pb contents in A. subulatus was roots>leaves>stems. The linear relationship of Pb isotope ratios ((206)Pb/(207)Pb and (208)Pb/(206)Pb) among soil, plant and aerosol samples were found. Based on the simple binary Pb isotopic model using the mean (206)Pb/(207)Pb ratios in TSP and in SSA, the approximate contributions of airborne Pb into plant leaves were 72.2% and 65.1%, respectively, suggesting that airborne Pb is the most important source for the Pb accumulation in leaves. So the combination of Pb isotope tracing and the simple binary Pb isotope model can assess the contribution of airborne Pb into plant leaves and may be of interest for risk assessment of the exposure to airborne Pb contamination.

  12. Time differences in the formation of meteorites as determined from the ratio of lead-207 to lead-206

    USGS Publications Warehouse

    Tatsumoto, M.; Knight, R.J.; Allegre, C.J.

    1973-01-01

    Measurements of the lead isotopic composition and the uranium, thorium, and lead concentrations in meteorites were made in order to obtain more precise radiometric ages of these members of the solar system. The newly determined value of the lead isotopic composition of Canyon Diablo troilite is as follows: 206Pb/204Pb = 9.307, 207Pb/204Pb = 10.294, and 208Pb/204Pb = 29.476. The leads of Angra dos Reis, Sioux County, and Nuevo Laredo achondrites are very radiogenic, the 206Pb/204Pb values are about 200, and the uranium-thorium-lead systems are nearly concordant. The ages of the meteorites as calculated from a single-stage 207Pb/206Pb isochron based on the newly determined primordial lead value and the newly reported 235U and 238U decay constants, are 4.528 ?? 10 9 years for Sioux County and Nuevo Laredo and 4.555 ?? 10 9 years for Angra dos Reis. When calculated with the uranium decay constants used by Patterson, these ages are 4.593 ?? 109 years and 4.620 ?? 109 years, respectively, and are therefore 40 to 70 ?? 106 years older than the 4.55 ?? 109 years age Patterson reported. The age difference of 27 ?? 106 years between Angra dos Reis and the other two meteorites is compatible with the difference between the initial 87Sr/86Sr ratio of Angra dos Reis and that of seven basaltic achondrites observed by Papanastassiou and Wasserburg. The time difference is also comparable to that determined by 129I-129Xe chronology. The ages of ordinary chondrites (H5 and L6) range from 4.52 to 4.57 ?? 109 years, and, here too, time differences in the formation of the parent bodies or later metamorphic events are indicated. Carbonaceous chondrites (C2 and C3) appear to contain younger lead components.

  13. Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead.

    PubMed

    Yang, Sha; Liu, Yun

    2015-01-01

    The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac's formalism of full-electron wave function. Equilibrium (202)Hg/(198)Hg, (205)Tl/(203)Tl, (207)Pb/(206)Pb and (208)Pb/(206)Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of [formula in text] for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb(4+)-bearing species are found can enrich heavier Pb isotopes than Pb(2+)-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of (208)Pb/(206)Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb(2+)-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., [formula in text]) and odd-mass MIFs (i.e., [formula in text) are almost the same but with opposite signs. PMID:26224248

  14. Spatial Distribution of Lead Isotope Ratios and Inorganic Element Concentrations in Epiphytic Lichens from the Athabasca Oil Sands Region

    NASA Astrophysics Data System (ADS)

    Graney, J. R.; Landis, M. S.; Puckett, K.; Edgerton, E.; Krupa, S.; Percy, K.

    2013-12-01

    Coupled studies of inorganic element concentrations and lead (Pb) isotope ratios have been conducted on Hypogymnia physodes samples collected in the Athabasca Oil Sands Region (AOSR) in Alberta, Canada in 2002, 2008, and 2011. To investigate the spatial extent of air emissions, the lichens were collected from sites as far as 160 km from the mining and processing operations. 30 milligram sub-samples of the lichens were microwave digested, and the extracts were analyzed using DRC-ICPMS to determine elemental concentrations, and sector field ICPMS to measure Pb isotope ratios. Concentrations of elements in the lichens were found to reflect proximity to mining and oil processing sites as well as topography, ecosystem differences, and the metabolic biogeochemistry of the lichens. An exponential decrease in concentration of metals associated with fugitive dust (aluminum and others) versus distance from the mining sites, suggests elevated coarse particle emissions associated with mining operations. Near source concentrations of metals with an oil signature (vanadium and others) are less enhanced and more homogeneous than the metals in the fugitive dust, reflecting emission and deposition of smaller diameter particles at greater distances from oil processing sources. The mining and oil processing signatures are superimposed over elemental concentrations that reflect the nutrient needs of the lichens. These findings are being confirmed through ongoing studies using dichot samplers to collect coarse and fine particulate aerosol samples. The lichen samples collected beyond 50 km from the mining and processing sites cluster into a Pb isotope grouping with a 207Pb / 206Pb ratio of 0.8650 and a 208Pb / 206Pb ratio near 2.095. This grouping likely reflects the regional background Pb isotope ratio signature. 207Pb / 206Pb and 208Pb / 206Pb ratios decrease as one nears the mining and processing operations. This indicates that other Pb source(s), (e.g. Pb in the bitumen from the oil

  15. U-Th-Pb isotope data indicate phanerozoic age for oxidation of the 3.4 Ga Apex Basalt

    NASA Astrophysics Data System (ADS)

    Li, Weiqiang; Johnson, Clark M.; Beard, Brian L.

    2012-02-01

    The occurrence of ferric oxides in Archean rocks has played an important role in discussions on the amount of free oxygen in the atmosphere of the ancient Earth. Recognizing that post-Archean weathering may also produce oxide minerals, drill cores have been used to obtain samples beneath the depth of Phanerozoic weathering. The first core of the Archean Biosphere Drilling Project (ABDP-1) documented hematite as alteration products in 3.4 Ga basalts from the Marble Bar area of the Pilbara Craton, NW Australia, and this has been used to infer the presence of an O2-bearing atmosphere in the Archean. It is possible, however, that despite recovery of samples from > 100 m depth, oxidation of the basalts occurred much younger than the depositional age. In this study, the age of oxidation of the Apex Basalt from the ABDP-1 drill core at Marble Bar is constrained by U-Th-Pb geochronology. Lead and U concentrations of the basalts from the ABDP-1 drill core vary greatly, between < 1-58 ppm and 0.08-1.04 ppm, respectively, whereas Th contents are more restricted (0.24-0.71 ppm). 206Pb/204Pb ratios are non-radiogenic and vary from 12.44 to 14.69. The linear array in terms of 206Pb/204Pb-207Pb/204Pb variations does not reflect an age but reflects two-component mixing between a non-radiogenic "ore lead" end member and a radiogenic "basalt lead" end member. The samples do not form isochrons on 238U/204Pb-206Pb/204Pb, 235U/204Pb-207Pb/204Pb, or 232Th/204Pb-208Pb/204Pb diagrams, indicating post-formation U and Pb addition. Comparison of measured U/Th ratios with "model" U/Th ratios calculated based on 208Pb/204Pb-206Pb/204Pb variations indicates that U enrichment most likely occurred in the last 200 Ma. The degree of U enrichment in the samples is correlated with Fe(III)/FeTotal ratios, indicating that U addition and oxidation were related, most likely reflecting penetration of oxygenated surface waters in the Phanerozoic along bedding planes and shear zones. These results

  16. Sr-Pb isotopic studies of primitive and near-primitive basaltic magmas, Garibaldi volcanic belt, northern Cascadia subduction system

    NASA Astrophysics Data System (ADS)

    Green, N. L.; Sinha, A. K.

    2003-12-01

    The northern Cascadia subduction system is intimately associated with aseismic subduction of extremely young and presumably `hot' oceanic lithosphere beneath northwestern Washington and southwestern British Columbia. Sr and Pb isotopic analyses are presented for primitive and near-primitive (>6.0 wt. % MgO) basalts from a southeast-northwest transect along the Garibaldi volcanic belt (GVB), which overlies subducted oceanic lithosphere that decreases in age from ca. 22 m.y. below Glacier Peak at its southern end to about 13 m.y. beneath the northernmost eruptive centers in the Mosaic (Meager Mountain) and Salal Glacier-Bridge River areas. The basaltic rocks have initial 87Sr/86Sr ratios of 0.70317-0.70426, with minimum observed values in individual lava suites decreasing northward. Values of Pb isotopic ratios for GVB basaltic suites range from 18.22 to 18.97 for 206Pb/204Pb, from 15.51 to 15.59 for 207Pb/204Pb, and from 37.73 to 38.49 for 208Pb/204Pb. Sr isotopic compositions, unsupported by lava Rb contents, show positive correlations with Cs/Rb, La/Nb, Ba/La, Ba/Nb, Ba/Ta, B/La, B/Zr, Sr/Nd, and primitive mantle normalized Sr/P; and negative correlations with high field strength elements (HFSE: Nb, and Ta), FeO and other transition metals (Co and Zn), Ce/Pb,Cr/Ni, Sm/Yb, Ta/Yb, Hf/Yb, K/Ba, K/Sr, and La/Yb. Moderate to strong correlations between 87Sr/86Sr and ratios involving fluid-mobile and less-fluid-mobile elements are compatible with decreased slab input northward along the volcanic front as the subducted plate becomes hotter. The Pb isotopic compositions exhibit only limited variations when examined against position along the volcanic arc, but show uniform to extremely weak positive correlations of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb with 87Sr/86Sr, Ba/La, Sr/Nd, Ba/Nb, Zr/Nb, Mg-Number and SiO2; and similarly weak negative correlation of Ce/Pb with 206Pb/204Pb and 207Pb/204Pb. The isotopic data suggest that GVB basaltic magmas have experienced with

  17. 207Pb and 119Sn solid-state NMR and relativistic density functional theory studies of the historic pigment lead-tin yellow type I and its reactivity in oil paintings.

    PubMed

    Catalano, Jaclyn; Murphy, Anna; Yao, Yao; Alkan, Fahri; Zumbulyadis, Nicholas; Centeno, Silvia A; Dybowski, Cecil

    2014-09-11

    Lead soaps (lead carboxylates) have been detected in traditional oil paintings in layers containing the pigment lead-tin yellow type I (LTY-I). LTY-I has been used by artists from at least the second quarter of the 15th century until the first half of the 18th century. Soap formation can lead to protrusions in paint layers and increased transparency, causing the paint support to become visible. We have characterized LTY-I by (119)Sn and (207)Pb solid-state NMR (ssNMR) spectroscopy. Using a combination of NMR techniques and DFT molecular cluster calculations, we identify the individual species in LTY-I and determine their (119)Sn and (207)Pb chemical-shift tensors. The presence of starting materials from the synthesis, minium, and tin(IV) oxide was also verified. Knowledge of the chemical-shift tensor components and the impurities in LTY-I is important for examining the chemistry of degradation processes and soap formation. We demonstrate that ssNMR can be used to detect reaction between Pb2SnO4 and added palmitic acid in a model paint sample containing LTY-I. PMID:25144651

  18. Improved 206Pb/238U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID-TIMS, ELA-ICP-MS and oxygen isotope documentation for a series of zircon standards

    USGS Publications Warehouse

    Black, L.P.; Kamo, S.L.; Allen, C.M.; Davis, D.W.; Aleinikoff, J.N.; Valley, J.W.; Mundil, R.; Campbell, I.H.; Korsch, R.J.; Williams, I.S.; Foudoulis, C.

    2004-01-01

    Precise isotope dilution-thermal ionisation mass spectrometry (ID-TIMS) documentation is given for two new Palaeozoic zircon standards (TEMORA 2 and R33). These data, in combination with results for previously documented standards (AS3, SL13, QGNG and TEMORA 1), provide the basis for a detailed investigation of inconsistencies in 206Pb/238U ages measured by microprobe. Although these ages are normally consistent between any two standards, their relative age offsets are often different from those established by ID-TIMS. This is true for both sensitive high-resolution ion-microprobe (SHRIMP) and excimer laser ablation-inductively coupled plasma-mass spectrometry (ELA-ICP-MS) dating, although the age offsets are in the opposite sense for the two techniques. Various factors have been investigated for possible correlations with age bias, in an attempt to resolve why the accuracy of the method is worse than the indicated precision. Crystallographic orientation, position on the grain-mount and oxygen isotopic composition are unrelated to the bias. There are, however, striking correlations between the 206Pb/238U age offsets and P, Sm and, most particularly, Nd abundances in the zircons. Although these are not believed to be the primary cause of this apparent matrix effect, they indicate that ionisation of 206Pb/238U is influenced, at least in part, by a combination of trace elements. Nd is sufficiently representative of the controlling trace elements that it provides a quantitative means of correcting for the microprobe age bias. This approach has the potential to reduce age biases associated with different techniques, different instrumentation and different standards within and between laboratories. Crown Copyright ?? 2004 Published by Elsevier B.V. All rights reserved.

  19. Dispersal of natural and anthropogenic lead through submarine canyons at the Portuguese margin

    NASA Astrophysics Data System (ADS)

    Richter, T. O.; de Stigter, H. C.; Boer, W.; Jesus, C. C.; van Weering, T. C. E.

    2009-02-01

    Submarine canyons represent natural conduits for preferential transport of particulate material, including anthropogenic contaminants, from coastal zones directly to the deep sea. To assess related dispersal of natural and anthropogenic lead (Pb), we analyzed Pb concentrations and stable isotope ratios in surface sediments and sediment trap particulate material from the Portuguese margin Nazaré and Setúbal/Lisbon canyons. Geochemical data are integrated with previously obtained data on near-bottom hydrodynamics and processes and pathways of sediment transport. The two canyon systems are located in close geographic proximity to each other, but represent contrasting settings in terms of sediment input and down-canyon sediment transport processes. Concentration-isotope diagrams and three-isotope plots ( 206Pb/ 207Pb vs. 208Pb/ 206Pb) suggest binary mixing between natural and anthropogenic end members. The inferred isotopic signature of pollutant Pb ( 206Pb/ 207Pb=1.143 [1.134-1.149, 95% confidence interval]) is most consistent with industrial Pb; ongoing influence from gasoline Pb additives is at most of minor importance. Two proposed natural end members most likely bracket the isotopic signature of natural Pb. Accordingly, binary mixing calculations indicate that on average 20-45% vs. 35-55% of total Pb is derived from anthropogenic sources in the Nazaré and Setúbal-Lisbon canyon systems, respectively. Enhanced anthropogenic influence in the latter area is consistent with its proximity to heavily populated and industrialized areas and with sediment input from the Tagus and Sado rivers, potential major carriers of pollutant particles. In both canyon systems, the anthropogenic component generally decreases with increasing water depth. Isotopic signatures of sediment trap particulate material are generally consistent with surface sediment data at similar water depth, but show large variability in the upper Nazaré canyon and major deviations from surface sediments

  20. Pb-isotopic Features of Primitive Rocks from Hess Deep: Distinguishing between EPR and Cocos-Nazca Mantle Source(s)

    NASA Astrophysics Data System (ADS)

    Jean, M. M.; Falloon, T.; Gillis, K. M.

    2014-12-01

    We have acquired high-precision Pb-isotopic signatures of primitive lithologies (basalts/gabbros) recovered from IODP Expedition 345.The Hess Deep Rift, located in the vicinity of the Galapagos triple junction (Cocos, Nazca, and Pacific), is viewed as one the best-studied tectonic windows into fast-spreading crust because a relatively young (<1.5 Ma) cross section of oceanic crust. This allows for (1) characterization of the mantle source(s) at Hess Deep, (2) insight into the extent of isotopic homogeneity or heterogeneity in the area, and (3) constrain the relative contributions from the intruding Cocos-Nazca spreading center. The observed Pb-isotopic variation at Hess Deep covers almost the entire range of EPR MORB (10°N to -5°S). Hess Deep samples range from 208Pb (37.3-38.25), 207Pb (15.47-15.58), 206Pb (17.69-18.91). These compositions suggest that this part of Hess Deep mantle is no more isotopically homogeneous than EPR mantle. Two distinct arrays are also observed: 208Pb-enriched (r2=0.985; n=30) and 208Pb-depleted (r2=0.988; n=6). The 208Pb/204Pb isotopes indicates that the Pb-source for some of the samples at Hess Deep had very low Th/U ratios, whereas other areas around the Galapagos microplate seem to have more "normal" ratios. These trends are less apparent when viewed with 207Pb-isotopes. Instead, the majority of basalts and gabbros follow the NHRL, however, at the depleted-end of this array a negative excursion to more enriched compositions is observed. This negative but linear trend could signify an alteration trend or mixing with an EMI-type mantle source, yet this mixing is not observed with 208Pb. This trend is also observed at Pito Deep, which has similar origins to Hess Deep (Barker et al., 2008; Pollack et al., 2009). The Galapagos region has been considered a testing ground for mixing of HIMU, Enriched Mantle, and Depleted Mantle reservoirs (e.g., Schilling et al., 2002). According to our data, however, an EPR-component must also be

  1. Extended optical model analyses of elastic scattering and fusion cross sections for the {sup 6}Li+{sup 208}Pb system at near-Coulomb-barrier energies using a folding potential

    SciTech Connect

    So, W. Y.; Udagawa, T.; Kim, K. S.; Hong, S. W.; Kim, B. T.

    2007-02-15

    Based on the extended optical model approach in which the polarization potential is decomposed into direct reaction (DR) and fusion parts, simultaneous {chi}{sup 2} analyses are performed for elastic scattering and fusion cross section data for the {sup 6}Li+{sup 208}Pb system at near-Coulomb-barrier energies. A folding potential is used as the bare potential. It is found that the real part of the resultant DR part of the polarization potential is repulsive, which is consistent with the results from the continuum discretized coupled channel (CDCC) calculations and the normalization factors needed for the folding potentials. Further, it is found that both DR and fusion parts of the polarization potential satisfy separately the dispersion relation.

  2. Characteristics and genesis of mineral deposits in East Ujimqin Banner, western segment of the Great Xing'an Mountains, NE China

    NASA Astrophysics Data System (ADS)

    Zhang, Wanyi; Nie, Fengjun; Liu, Shuwen; Zuo, Liyan; Yao, Xiaofeng; Jia, Delong; Liu, Jiangtao

    2015-01-01

    The East Ujimqin Banner, located in the western segment of the Great Xing'an Mountains, NE China, has undergone a long and multi-stage tectonic evolution, which has resulted in significant Fe-Ag-Pb-Zn-Au-Cu-Mo deposits. There are two main types of mineralization: vein and skarn types. The Jilinbaolige and Aerhada vein deposits, and the Chagan Obo and Chaobuleng skarn-type deposits are four typical deposits in this area. The vein deposits mainly occur as veins with hydrothermal alteration in fractures within pre-mineralization clastic rocks and felsic volcanic rocks. The skarn-type deposits always show a temporal and spatial relationship with Mesozoic granite intruded into Paleozoic limestone. The sulfur isotope data from the sulfides in these four deposits have a very narrow range (+1‰ to +8‰), suggesting that most were derived from magma. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios range from 17.949 to 18.529, 15.370 to 15.691 and 37.653 to 38.460 respectively, indicating that the metals derive mainly from the mantle source. In the diagrams 207Pb/204Pb vs. 206Pb/204Pb and 208Pb/204Pb vs. 206Pb/204Pb, the points of lead isotope of the sulfide ores are very near or coincide to the K-feldspar, indicating that the ore-forming materials sources have the genetic relationship. It seems that there are four key factors controlling the mineralization styles in this district: the tectonic setting, magmatic activity, wall rocks, and structures. The superposition of multi-stage tectonism from a Mesozoic extensional setting on a Paleozoic subduction setting provided a remobilization and enrichment mechanism for the ore-forming elements. The magmatic activities were sources of metals and fluids, and drove them to the mineralization sites. The wall rocks are key factors for mineralization styles. When metal-bearing fluid flows into clastic rocks and felsic volcanic rocks, the mineralization is mainly vein type, and mineralization in limestone is mainly skarn type. NE

  3. A study of radionuclides, metals and stable lead isotope ratios in sediments and soils in the vicinity of natural U-mineralisation areas in the Northern Territory.

    PubMed

    Frostick, A; Bollhöfer, A; Parry, D

    2011-10-01

    Australian guidelines recommend that tailings materials from uranium (U) mining and milling be contained without any detrimental impact on the environment for at least 1000 years. Natural analogue sites are being investigated to determine if they can provide data on the rates of natural erosion processes which occur over these timescales, for input into predictive geomorphic computer models. This paper presents radionuclide, metal and stable lead (Pb) isotope data from sediment cores and surface soils in the vicinity of two mineralised areas in the Alligator Rivers Region. Surface scrapes from the natural Anomaly #2, south of the Ranger mineral lease, exhibit radiogenic (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios, and elevated U and metal concentrations typical for a near surface U anomaly. In contrast, samples taken from the Koongarra mineral lease (KML) show radionuclide activity and metal concentrations similar to natural areas elsewhere in the Alligator Rivers Region and Pb isotope ratios are closer to present day average crustal ratios (PDAC), as the orebodies at KML are covered by surficial sand. A sediment core collected from Anbangbang Billabong, downstream of KML, exhibits small variations in Pb isotope ratios that indicate that approximately 1% of the upper sediments in the sediment core may be derived from material originating from the U anomaly at Koongarra.

  4. Reconstructing lead isotope exposure histories preserved in the growth layers of walrus teeth using the SHRIMP II ion microprobe

    SciTech Connect

    Stern, R.A.; Outridge, P.M.; Davis, W.J.; Stewart, R.E.A.

    1999-05-15

    Development of a microprobe technique to determine Pb isotope ratios within the growth layers of mammal teeth could have widespread applications in Pb toxicology, Pb pollution tracing, and human and animal ecology. Here, the SHRIMP II ion microprobe is shown to possess sufficient sensitivity, accuracy, and precision to satisfactorily determine Pb isotope ratios in the canine tooth cementum of a walrus (Odobenus rosmarus rosmarus), with a sampling resolution of 130 {micro}m. The tooth layers were estimated to contain only 1--3 {micro}g/gf Pb. By combining multiple replicates within each annual layer, the {+-}1 SE uncertainty was typically {+-}1% for {sup 206}Pb/{sup 207}Pb and {+-}0.5% for {sup 208}Pb/{sup 207}Pb. Significant isotopic differences were found between layers deposited at age 10 and ages 2, 27, and 30. This result, together with corroborative data on excised cementum fragments analyzed by thermal ionization mass spectrometry, indicates that the animal migrated into different geological terrains several times during its life. There was no evidence of exchange between the Pb deposited in early growth layers and more recent ambient Pb.

  5. Spatial distribution, health risk assessment, and isotopic composition of lead contamination of street dusts in different functional areas of Beijing, China.

    PubMed

    Han, Lanfang; Gao, Bo; Wei, Xin; Xu, Dongyu; Gao, Li

    2016-02-01

    Street dusts from heavy density traffic area (HDTA), tourism area (TA), residential area (RA), and educational area (EA) in Beijing were collected to explore the distribution, health risk assessment, and source of lead (Pb). The average concentration of Pb in TA was the highest among the four areas. Compared with other cities, Pb concentrations in Beijing were generally at moderate or low levels. The average value (14.05) of ecological risk index (RI) indicated that Pb was at "low pollution risk" status. According to the calculation on hazard index (HI), the ingestion of dust particles of children and adults was the major route of exposure to street dusts in four studied areas, followed by dermal contact. The lower values of HI than 1 further suggested that non-carcinogenic risks of Pb in the street dusts were in the low range. Comparing (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of street dusts with other environmental samples, it was found that atmospheric deposition of coal combustion dust might be the main pathway for anthropogenic Pb input to the street dusts in four functional areas. PMID:26490894

  6. Spatial distribution, health risk assessment, and isotopic composition of lead contamination of street dusts in different functional areas of Beijing, China.

    PubMed

    Han, Lanfang; Gao, Bo; Wei, Xin; Xu, Dongyu; Gao, Li

    2016-02-01

    Street dusts from heavy density traffic area (HDTA), tourism area (TA), residential area (RA), and educational area (EA) in Beijing were collected to explore the distribution, health risk assessment, and source of lead (Pb). The average concentration of Pb in TA was the highest among the four areas. Compared with other cities, Pb concentrations in Beijing were generally at moderate or low levels. The average value (14.05) of ecological risk index (RI) indicated that Pb was at "low pollution risk" status. According to the calculation on hazard index (HI), the ingestion of dust particles of children and adults was the major route of exposure to street dusts in four studied areas, followed by dermal contact. The lower values of HI than 1 further suggested that non-carcinogenic risks of Pb in the street dusts were in the low range. Comparing (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of street dusts with other environmental samples, it was found that atmospheric deposition of coal combustion dust might be the main pathway for anthropogenic Pb input to the street dusts in four functional areas.

  7. Heavy metals pollution and pb isotopic signatures in surface sediments collected from Bohai Bay, North China.

    PubMed

    Gao, Bo; Lu, Jin; Hao, Hong; Yin, Shuhua; Yu, Xiao; Wang, Qiwen; Sun, Ke

    2014-01-01

    To investigate the characteristics and potential sources of heavy metals pollution, surface sediments collected from Bohai Bay, North China, were analyzed for the selected metals (Cd, Cr, Cu, Ni, Pb, and Zn). The Geoaccumulation Index was used to assess the level of heavy metal pollution. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of Cd, Cr, Cu, Ni, Pb, and Zn were 0.15, 79.73, 28.70, 36.56, 25.63, and 72.83 mg/kg, respectively. The mean concentrations of the studied metals were slightly higher than the background values. However, the heavy metals concentrations in surface sediments in Bohai Bay were below the other important bays or estuaries in China. The assessment by Geoaccumulation Index indicated that Cr, Zn, and Cd were classified as "the unpolluted" level, while Ni, Cu, and Pb were ranked as "unpolluted to moderately polluted" level. The order of pollution level of heavy metals was: Pb > Ni > Cu > Cr > Zn > Cd. The Pb isotopic ratios in surface sediments varied from 1.159 to 1.185 for (206)Pb/(207)Pb and from 2.456 to 2.482 for (208)Pb/(207)Pb. Compared with Pb isotopic radios in other sources, Pb contaminations in the surface sediments of Bohai Bay may be controlled by the mix process of coal combustion, aerosol particles deposition, and natural sources.

  8. Characteristics of heavy metals and Pb isotopic composition in sediments collected from the tributaries in three Gorges Reservoir, China.

    PubMed

    Gao, Bo; Zhou, Huaidong; Huang, Yong; Wang, Yuchun; Gao, Jijun; Liu, Xiaobo

    2014-01-01

    The concentrations, distribution, accumulation, and potential ecological risk of heavy metals (Cr, Cu, Zn, Ni, As, Pb, Cd, and Hg) in sediments from the Three Gorges Reservoir (TGR) tributaries were determined and studied. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of heavy metals in sediment of TGR tributaries were higher than the local background values of soils and sediments in China. The assessment by Geoaccumulation Index indicated that Cu, Ni, and Hg were at the "slightly polluted" level and Cd was ranked as the "moderately polluted" level in tributary sediments of TGR. The assessment by Potential Ecological Risk Index showed that Hg and Cd were the predominant elements in tributary sediments in TGR. The Pb isotopic ratios in sediments varied from 1.171 to 1.202 for (206)Pb/(207)Pb and from 2.459 to 2.482 for (208)Pb/(207)Pb in TGR. All Pb isotopic ratios in sediments were similar to those from coal combustion, lead ores (the mining activities and smelting process), and cement material, indicating that these anthropogenic inputs may be the main sources for Pb pollution in sediments of TGR tributaries.

  9. Trace Metal Inventories and Lead Isotopic Composition Chronicle a Forest Fire’s Remobilization of Industrial Contaminants Deposited in the Angeles National Forest

    PubMed Central

    Odigie, Kingsley O.; Flegal, A. Russell

    2014-01-01

    The amounts of labile trace metals: [Co] (3 to 11 µg g−1), [Cu] (15 to 69 µg g−1), [Ni] (6 to 15 µg g−1), [Pb] (7 to 42 µg g−1), and [Zn] (65 to 500 µg g−1) in ash collected from the 2012 Williams Fire in Los Angeles, California attest to the role of fires in remobilizing industrial metals deposited in forests. These remobilized trace metals may be dispersed by winds, increasing human exposures, and they may be deposited in water bodies, increasing exposures in aquatic ecosystems. Correlations between the concentrations of these trace metals, normalized to Fe, in ash from the fire suggest that Co, Cu, and Ni in most of those samples were predominantly from natural sources, whereas Pb and Zn were enriched in some ash samples. The predominantly anthropogenic source of excess Pb in the ash was further demonstrated by its isotopic ratios (208Pb/207Pb: 206Pb/207Pb) that fell between those of natural Pb and leaded gasoline sold in California during the previous century. These analyses substantiate current human and environmental health concerns with the pyrogenic remobilization of toxic metals, which are compounded by projections of increases in the intensity and frequency of wildfires associated with climate change. PMID:25259524

  10. Pyrogenic remobilization of historic industrial lead depositions.

    PubMed

    Odigie, Kingsley O; Flegal, A Russell

    2011-08-01

    Relatively high levels (4.3 to 51 μg/g) of labile lead (Pb) in ash from the 2009 Jesusita Fire in Santa Barbara County, California attest to the pyrogenic remobilization of historic industrial lead depositions in this relatively pristine area in Southern California, USA. The primarily industrial origin of that lead was evidenced by its poor correlations (simple linear regressions) with lithogenic aluminum (r = 0.18, p = 0.354, n = 30) and iron (r = 0.21, p = 0.270, n = 30) concentrations and by its associated enrichment factors (EFs): EF using aluminum as conservative element (f-Al) vs lead concentration [Pb] (r = 0.79, p < 0.001, n = 30), and EF using iron as conservative element (f-Fe) vs [Pb] (r = 0.83, p < 0.001, n = 30). The industrial origins of much of that lead were corroborated by its isotopic compositions ((206)Pb/(207)Pb and (208)Pb/(207)Pb), which fell between those of natural lead in the Santa Barbara Basin and previous leaded gasoline emissions in Southern California. This apparent pyrogenic remobilization of legacy lead pollution indicates that it-and other persistent pollutants-will increase with the projected increase in the frequency and intensity of forest fires in the Southwest U.S. and elsewhere as a consequence of climate change.

  11. Tracing the anthropogenic lead sources in coastal sediments of SE-pacific (36 degrees Lat. S) using stable lead isotopes.

    PubMed

    Muñoz, Práxedes N V; Garbe-Schönberg, Carl-Dieter; Salamanca, Marco A

    2004-04-01

    This study evaluates the main sources of antropogenic Pb in one of the most industrialized centers of the southern Chilean coast (36 degrees S). Stable lead isotopes ((206)Pb/(207)Pb, (208)Pb/(207)Pb) were used to trace main Pb sources to coastal sediments, considering the suspended particulate matter (SPM) from marine (traps), continental (rivers) and industrial effluents, sediments and leaded gasoline samples. The atmospheric input was evaluated through natural collectors; i.e. Raqui-Tubul salt marsh. Results show that marine samples lie on a trend between industrial effluents ( approximately 1.16, 2.44) and natural sources (1.20, 2.50), not related to gasoline consumption. Salt marsh sediments show comparable isotopic composition to marine samples, suggesting the importance of the atmospheric input in the coastal sediments, not related to the leaded gasoline composition either. The continental input (1.18, 2.48) is highly influenced by precipitation, being difficult to separate both sources (atmosphere and continental runoff), showing also similar isotopic ratio to marine sediments. The signal of industrial emissions is masked with the introduction of Pb with higher isotopic ratios, compared to the values observed in the material collected from traps (SPM approximately 1.19, 2.48). The contribution of more radiogenic Pb by the upwelling is suggested.

  12. Trace metal inventories and lead isotopic composition chronicle a forest fire's remobilization of industrial contaminants deposited in the angeles national forest.

    PubMed

    Odigie, Kingsley O; Flegal, A Russell

    2014-01-01

    The amounts of labile trace metals: [Co] (3 to 11 µg g-1), [Cu] (15 to 69 µg g-1), [Ni] (6 to 15 µg g-1), [Pb] (7 to 42 µg g-1), and [Zn] (65 to 500 µg g-1) in ash collected from the 2012 Williams Fire in Los Angeles, California attest to the role of fires in remobilizing industrial metals deposited in forests. These remobilized trace metals may be dispersed by winds, increasing human exposures, and they may be deposited in water bodies, increasing exposures in aquatic ecosystems. Correlations between the concentrations of these trace metals, normalized to Fe, in ash from the fire suggest that Co, Cu, and Ni in most of those samples were predominantly from natural sources, whereas Pb and Zn were enriched in some ash samples. The predominantly anthropogenic source of excess Pb in the ash was further demonstrated by its isotopic ratios (208Pb/207Pb: 206Pb/207Pb) that fell between those of natural Pb and leaded gasoline sold in California during the previous century. These analyses substantiate current human and environmental health concerns with the pyrogenic remobilization of toxic metals, which are compounded by projections of increases in the intensity and frequency of wildfires associated with climate change.

  13. Tracing the origin of pollution in French Alpine snow and aerosols using lead isotopic ratios.

    PubMed

    Veysseyre, A M; Bollhöfer, A F; Rosman, K J; Ferrari, C P; Boutron, C F

    2001-11-15

    Fresh snow samples collected at 15 remote locations and aerosols collected at one location in the French Alps between November 1998 and April 1999 have been analyzed for Pb concentration and isotopic composition by thermal ionization mass spectrometry. The snow samples contained 19-1300 pg/g of Pb with isotopic ratios 206Pb/207Pb (208Pb/207Pb) of 1.1279-1.1607 (2.3983-2.4302). Airborne Pb concentrations at one sampling site ranged from 0.42 to 6.0 ng/m3 with isotopic ratios of 1.1321-1.1427 (2.4029-2.4160). Air mass trajectory analysis combined with isotopic compositions of potential source regions did not show discernible evidence of the long-range atmospheric transport of pollutants. Isotopic ratios in the Alpine snow samples and thus the free troposphere were generally higher than airborne Pb isotopic ratios in urban France, which coupled with the relatively high Pb concentrations suggested a regional anthropogenic Pb source, probably Italy but possibly Eastern Europe.

  14. Source identification and apportionment of heavy metals in urban soil profiles.

    PubMed

    Luo, Xiao-San; Xue, Yan; Wang, Yan-Ling; Cang, Long; Xu, Bo; Ding, Jing

    2015-05-01

    Because heavy metals (HMs) occurring naturally in soils accumulate continuously due to human activities, identifying and apportioning their sources becomes a challenging task for pollution prevention in urban environments. Besides the enrichment factors (EFs) and principal component analysis (PCA) for source classification, the receptor model (Absolute Principal Component Scores-Multiple Linear Regression, APCS-MLR) and Pb isotopic mixing model were also developed to quantify the source contribution for typical HMs (Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn) in urban park soils of Xiamen, a representative megacity in southeast China. Furthermore, distribution patterns of their concentrations and sources in 13 soil profiles (top 20 cm) were investigated by different depths (0-5, 5-10, 10-20 cm). Currently the principal anthropogenic source for HMs in urban soil of China is atmospheric deposition from coal combustion rather than vehicle exhaust. Specifically for Pb source by isotopic model ((206)Pb/(207)Pb and (208)Pb/(207)Pb), the average contributions were natural (49%)>coal combustion (45%)≫traffic emissions (6%). Although the urban surface soils are usually more contaminated owing to recent and current human sources, leaching effects and historic vehicle emissions can also make deep soil layer contaminated by HMs.

  15. Primitive and contaminated basalts from the Southern Rocky Mountains, U.S.A

    USGS Publications Warehouse

    Doe, B.R.; Lipman, P.W.; Hedge, C.E.; Kurasawa, H.

    1969-01-01

    to the primitive basalts in lead isotope ratios. The primitive basalts have: 206Pb/204Pb ??? 18.09-18.34, 207Pb/204Pb ??? 15.5, 208Pb/204Pb ??? 37.6-37.9, 87Sr/86Sr ??? 0.704-0.705. In the primitive basalts from the Southern Rocky Mountains the values of 206Pb/204Pb are similar to values reported by others for Hawaiian and eastern Honshu basalts and abyssal basalts, whereas 208Pb/204Pb tends to be equal to or a little less radiogenic than those from the oceanic localities. 87Sr/86Sr appears to be equal to or a little greater than those of the oceanic localities. These 206Pb/204Pb and 208Pb/204Pb ratios are distinctly less radiogenic and 87Sr/86Sr values are about equal to those reported by others for volcanic islands on oceanic ridges and rises. ?? 1969 Springer-Verlag.

  16. Long-range transport of atmospheric lead reaching Ny-Ålesund: Inter-annual and seasonal variations of potential source areas

    NASA Astrophysics Data System (ADS)

    Bazzano, Andrea; Cappelletti, David; Udisti, Roberto; Grotti, Marco

    2016-08-01

    Atmospheric particulate matter (PM10) was collected at Ny-Ålesund (Svalbard Islands, Norwegian Arctic) during spring and summer from 2010 to 2014 and analysed for lead content, enrichment factor and isotopic composition (208Pb/206Pb and 207Pb/206Pb). It was found that atmospheric lead was mainly of anthropogenic origin and neither its mean concentration, nor its isotopic composition was subjected to significant inter-annual differences (p-value > 0.1). Seasonal differences in both lead content and isotopic compositions occurred (p-value < 0.001), with the exception of 2013 samples. Lead content in spring was higher than in summer. Isotopic analysis indicated that mining and smelting activities in the Rudny Altay region (Central Eurasia), as well as industrial emission in north-eastern North America, were the main sources of atmospheric lead in spring and summer, respectively. During 2013, no significant differences between the two seasons were found (p-value > 0.3), showing a prolonged influence of Eurasian sources also in summer. The results obtained by the Pb isotopic composition were corroborated by a back-trajectory cluster analysis of air-masses reaching the sampling site.

  17. Lead isotopes in the western North Atlantic: Transient tracers of pollutant lead inputs

    SciTech Connect

    Veron, A.J. |; Church, T.M.; Flegal, A.R.

    1998-08-01

    In the early 1980s, Patterson and colleagues demonstrated that most lead in oceanic surface waters had an anthropogenic origin. Their discovery occurred during the phasing out of leaded gasoline in North America initiated in the previous decade. The corresponding decrease in anthropogenic lead emissions, verified by Pb/{sup 210}Pb ratios, accounted for the systematic decline in lead concentrations in surface waters of the western Sargasso Sea. Subsequent changes in anthropogenic lead inputs to the western Sargasso Sea surface waters have been documented by measurements of lead concentrations, isotopic compositions ({sup 206}Pb/{sup 207}Pb, {sup 208}Pb/{sup 206}Pb), and Pb/{sup 210}Pb ratios in precipitation and seawater for the period of 1981 to 1994. These data indicate the easterly trade winds are now the primary source of atmospheric lead in Bermuda, and they confirm that the decline of lead concentrations in the North Atlantic is associated with the phasing out of leaded gasoline in North America and western Europe over the past decade. Moreover, temporal variations in the relative contribution of industrial lead inputs from the two sides of the North Atlantic over that period can be quantified based on differences in their isotopic composition. The transient character of those isotopic signatures also allows calculations of pollutant lead penetration rates into the mixed layer and upper thermocline of the western Sargasso Sea.

  18. Identifying the sources and timing of ancient and medieval atmospheric lead pollution in England using a peat profile from Lindow bog, Manchester.

    PubMed

    Le Roux, Gaël; Weiss, Dominik; Grattan, John; Givelet, Nicolas; Krachler, Michael; Cheburkin, Andriy; Rausch, Nicole; Kober, Bernd; Shotyk, William

    2004-05-01

    A peat core from Lindow bog near Manchester, England, was precisely cut into 2 cm slices to provide a high-resolution reconstruction of atmospheric Pb deposition. Radiocarbon and (210)Pb age dates show that the peat core represents the period ca. 2000 BC to AD 1800. Eleven radiocarbon age dates of bulk peat samples reveal a linear age-depth relationship with an average temporal resolution of 18.5 years per cm, or 37 years per sample. Using the Pb/Ti ratio to calculate the rates of anthropogenic, atmospheric Pb deposition, the profile reveals Pb contamination first appearing in peat samples dating from ca. 900 BC which clearly pre-date Roman mining activities. Using TIMS, MC-ICP-MS, and SF-ICP-MS to measure the isotopic composition of Pb, the (208)Pb/(206)Pb and (206)Pb/(207)Pb data indicate that English ores were the predominant sources during the pre-Roman, Roman, and Medieval Periods. The study shows that detailed studies of peat profiles from ombrotrophic bogs, using appropriate preparatory and analytical methods, can provide new insight into the timing, intensity, and predominant sources of atmospheric Pb contamination, even in samples dating from ancient times.

  19. Identifying the sources and timing of ancient and medieval atmospheric lead pollution in England using a peat profile from Lindow bog, Manchester.

    PubMed

    Le Roux, Gaël; Weiss, Dominik; Grattan, John; Givelet, Nicolas; Krachler, Michael; Cheburkin, Andriy; Rausch, Nicole; Kober, Bernd; Shotyk, William

    2004-05-01

    A peat core from Lindow bog near Manchester, England, was precisely cut into 2 cm slices to provide a high-resolution reconstruction of atmospheric Pb deposition. Radiocarbon and (210)Pb age dates show that the peat core represents the period ca. 2000 BC to AD 1800. Eleven radiocarbon age dates of bulk peat samples reveal a linear age-depth relationship with an average temporal resolution of 18.5 years per cm, or 37 years per sample. Using the Pb/Ti ratio to calculate the rates of anthropogenic, atmospheric Pb deposition, the profile reveals Pb contamination first appearing in peat samples dating from ca. 900 BC which clearly pre-date Roman mining activities. Using TIMS, MC-ICP-MS, and SF-ICP-MS to measure the isotopic composition of Pb, the (208)Pb/(206)Pb and (206)Pb/(207)Pb data indicate that English ores were the predominant sources during the pre-Roman, Roman, and Medieval Periods. The study shows that detailed studies of peat profiles from ombrotrophic bogs, using appropriate preparatory and analytical methods, can provide new insight into the timing, intensity, and predominant sources of atmospheric Pb contamination, even in samples dating from ancient times. PMID:15152320

  20. Subducted upper and lower continental crust contributes to magmatism in the collision sector of the Sunda-Banda arc, Indonesia

    NASA Astrophysics Data System (ADS)

    Elburg, M. A.; van Bergen, M. J.; Foden, J. D.

    2004-01-01

    Pb isotopes in igneous rocks from the Banda-Sunda arc show extreme along-arc variations, which correspond to major lithologic changes in crustal components entering the subduction system. An increase in 206Pb/204Pb ratios toward the zone of collision with the Australian continent reflects input of subducted upper-crustal material; maximum values coincide with anomalously radiogenic 3He/4He ratios that have been earlier attributed to the involvement of the continental margin. The collision zone is further characterized by 208Pb/204Pb ratios that are higher for a given 207Pb/204Pb value than observed in the noncollisional sectors, and in the central part of the collision zone, the 206Pb/204Pb ratios are lower than the most radiogenic values in the adjacent areas. We propose that these Pb isotope signatures reflect input of subducted lower crust, mobilized as a result of slab-window formation during arc-continent collision. Variations in Pb isotopes in the collision zone are solely determined by variations in the nature and proportions of different subducted components. The Pb isotope arrays in the noncollision area may be dominated by slab components as well and could reflect mixing between subducted oceanic crust and entrained sediments, rather than between subarc mantle and subducted sediments. Our new interpretation of the Indonesian Pb isotope data does not call for involvement of ocean-island basalt (OIB) type mantle or Australian subcontinental lithospheric mantle, as has been suggested previously.

  1. Influence of paint chips on lead concentration in the soil of public playgrounds in Tokyo.

    PubMed

    Takaoka, Michie; Yoshinaga, Jun; Tanaka, Atsushi

    2006-03-01

    Lead concentration in the surface soils from 31 playgrounds in a ward in Tokyo was measured to examine if paint chips, peeled off from playing equipment installed in the playgrounds, contribute to elevated Pb concentration in the soil of public playgrounds. Lead concentration in the paint chips sampled from playgrounds ranged from 0.003 to 8.9%. Lead concentration in the surface soil ranged from 15.2 to 237 mg kg(-1) (average, 55.5 mg kg(-1)) and higher Pb concentration was found in the soil near painted playing equipment indicating that paint chips from playing equipment contributed to increase soil Pb level of playgrounds in Tokyo. The degree of peeling-off of paint on the surface of playing equipment in the public playground (peeling-off index: POI) positively correlated with Pb concentration in the soil (Spearman rank-correlation coefficient, r = 0.366, p = 0.043). The stronger correlation between Pb concentration and isotope ratios (207Pb/206Pb and Pb conc., r = 0.536, p = 0.002, 208Pb/206Pb and Pb conc. r = 0.600, p < 0.001) than that between Pb and POI indicated that gasoline Pb contributed more to the playground-to-playground variation in soil Pb concentration. It was concluded that both gasoline Pb of the past and paint chips contributed to increased Pb concentration in the surface soil of playgrounds in Tokyo, though the contribution of paint chips is smaller than gasoline Pb.

  2. High-precision analysis on annual variations of heavy metals, lead isotopes and rare earth elements in mangrove tree rings by inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Yu, Ke-Fu; Kamber, Balz S.; Lawrence, Michael G.; Greig, Alan; Zhao, Jian-Xin

    2007-02-01

    Annual variations from 1982 to 1999 of a wide range of trace elements and reconnaissance Pb isotopes ( 207Pb/ 206Pb and 208Pb/ 206Pb) were analyzed by solution ICP-MS on digested ash from mangrove Rhizophora apiculata, obtained from Leizhou Peninsula, along northern coast of South China Sea. The concentrations of the majority of elements show a weak declining trend with growth from 1982 to 1999, punctuated by several high concentration spikes. The declining trends are positively correlated with ring width and negatively correlated with inferred water-use efficiency, suggesting a physiological control over metal-uptake in this species. The episodic metal concentration-peaks cannot be interpreted with lateral movement or growth activities and appear to be related to environmental pollution events. Pb isotope ratios for most samples plot along the 'Chinese Pb line' and clearly document the importance of gasoline Pb as a source of contaminant. Shale-normalised REE + Y patterns are relatively flat and consistent across the growth period, with all patterns showing a positive Ce anomaly and elevated Y/Ho ratio. The positive Ce anomaly is observed regardless of the choice of normaliser, in contrast to previously reported REE patterns for terrestrial and marine plants. This pilot study of trace element, REE + Y and Pb isotope distribution in mangrove tree rings indicates the potential use of mangroves as monitors of historical environmental change.

  3. Pb, Sr, and Nd isotopes in basalts and sulfides from the Juan de Fuca Ridge

    SciTech Connect

    Hegner, E.; Tatsumoto, M.

    1987-10-10

    Pb, Sr, Nd isotopes of seven basalt glasses collected by the submersible Alvin from the southern Juan de Fuca Ridge (SJFR) are almost identical (/sup 206/Pb//sup 204/Pbapprox.18.45, /sup 207/Pb//sup 204/Pbapprox.15.47, /sup 208/Pb//sup 204/Pbapprox.37.81, /sup 87/Sr//sup 86/Srapprox.0.70249, /sup 143/Nd//sup 144/Ndapprox.0.51315). Whereas all basalts appear cogenetic, four of the samples have uniform abundances of U, Th, Rb, Nd, Sm, Pb, and Sr, indicating that they are also comagmatic. Two basalt glasses dredged previously at the SJFR have similar isotopic compositions but higher concentrations of U, Th, and Pb. The /sup 206/Pb//sup 204/Pb ratios are intermediate between generally less radiogenic ridge basalts from south of the Juan de Fuca Ridge (JFR) and often more radiogenic basalts from the northern JFR and NE Pacific seamounts. Sr and Nd isotopic compositions closely resemble data of other ridge basalts from the northernmost East Pacific Rise and are intermediate between isotopically more diverse seamount basalts produced nearby.

  4. The source of natural and anthropogenic heavy metals in the sediments of the Minjiang River Estuary (SE China): implications for historical pollution.

    PubMed

    Xu, Yonghang; Sun, Qinqin; Yi, Liang; Yin, Xijie; Wang, Aijun; Li, Yunhai; Chen, Jian

    2014-09-15

    Two sedimentary cores in the Minjiang River estuary (SE China) are documented for grain size, clay minerals, heavy metals, magnetic parameters and Pb isotopes to investigate the source and historical variation of heavy metals. The MJK9 core was collected outside of the Minjiang River estuary, and the core is composed of mixed sediments, of which ~70% from the Yangtze River and 30% from the Minjiang River. It is thus difficult to be used for tracing the human activity along the Minjiang River. In contrast, the sediments of MJK16 core which was collected in a nearshore area are primarily from the Minjiang River. The enrichment factors of the sediments were <1.5, indicating minor pollution. The results indicate that the sediments of the MJK16 core have Cu and Pb concentrations increasing since 1980, associated with the increase of magnetic mineral concentration and (206)Pb/(207)Pb and (206)Pb/(208)Pb of the sediments. We compared the Pb isotopic compositions between our results and those for the deposit mining in the Minjiang River basin, and aerosols and coal dust in south China, and considered that Pb in the sediments of the MJK16 core was derived primarily from weathered rocks as well as industrial emission (e.g. coal combustion). The sediments have anthropogenic Pb concentrations ranging from 6% in 1950 to 23.7% in 2010, consistent with the impact of rapid urban and industrial development in China. PMID:24995639

  5. Ancient bronze coins from Mediterranean basin: LAMQS potentiality for lead isotopes comparative analysis with former mineral

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Italiano, A.; Torrisi, A.

    2016-11-01

    Bronze coins coming from the area of the Mediterranean basin, dated back the II-X Cent. A.D., were analyzed using different physical analytical techniques. Characteristic X-ray fluorescence was used with electrons and photons, in order to investigate the elemental composition of both the surface layers and bulk. Moreover, the quadrupole mass spectrometry coupled to laser ablation (LAMQS technique) in high vacuum was used to analyse typical material compounds from surface contamination. Mass spectrometry, at high resolution and sensitivity, extended up to 300 amu, allowed measuring the 208Pb/206Pb and 207Pb/206Pb isotopic ratios into the coins. Quantitative relative analyses of these isotopic ratios identify the coin composition such as a "fingerprint" depending on the mineral used to extract the lead. Isotopic ratios in coins can be compared to those of the possible minerals used to produce the bronze alloy. A comparison between the measured isotope ratios in the analyzed coins and the literature database, related to the mineral containing Pb as a function of its geological and geophysical extraction mine, is presented. The analysis, restricted to old coins and the mines of the Mediterranean basin, indicates a possible correlation between the coin compositions and the possible geological sites of the extracted mineral.

  6. Asian industrial lead inputs to the North Pacific evidenced by lead concentrations and isotopic compositions in surface waters and aerosols.

    PubMed

    Gallon, Céline; Ranville, Mara A; Conaway, Christopher H; Landing, William M; Buck, Clifton S; Morton, Peter L; Flegal, A Russell

    2011-12-01

    Recent trends of atmospheric lead deposition to the North Pacific were investigated with analyses of lead in aerosols and surface waters collected on the fourth Intergovernmental Oceanographic Commission Contaminant Baseline Survey from May to June, 2002. Lead concentrations of the aerosols varied by 2 orders of magnitude (0.1-26.4 pmol/m(3)) due in part to variations in dust deposition during the cruise. The ranges in lead aerosol enrichment factors relative to iron (1-119) and aluminum (3-168) were similar, evidencing the transport of Asian industrial lead aerosols across the North Pacific. The oceanic deposition of some of those aerosols was substantiated by the gradient of lead concentrations of North Pacific waters, which varied 3-fold (32.7-103.5 pmol/kg), were highest along with the Asian margin of the basin, and decreased eastward. The hypothesized predominance of Asian industrial lead inputs to the North Pacific was further corroborated by the lead isotopic composition of ocean surface waters ((206)Pb/(207)Pb = 1.157-1.169; (208)Pb/(206)Pb = 2.093-2.118), which fell within the range of isotopic ratios reported in Asian aerosols that are primarily attributed to Chinese industrial lead emissions.

  7. Improved Discrimination for Brassica Vegetables Treated with Agricultural Fertilizers Using a Combined Chemometric Approach.

    PubMed

    Yuan, Yuwei; Hu, Guixian; Chen, Tianjin; Zhao, Ming; Zhang, Yongzhi; Li, Yong; Xu, Xiahong; Shao, Shengzhi; Zhu, Jiahong; Wang, Qiang; Rogers, Karyne M

    2016-07-20

    Multielement and stable isotope (δ(13)C, δ(15)N, δ(2)H, δ(18)O, (207)Pb/(206)Pb, and (208)Pb/(206)Pb) analyses were combined to provide a new chemometric approach to improve the discrimination between organic and conventional Brassica vegetable production. Different combinations of organic and conventional fertilizer treatments were used to demonstrate this authentication approach using Brassica chinensis planted in experimental test pots. Stable isotope analyses (δ(15)N and δ(13)C) of B. chinensis using elemental analyzer-isotope ratio mass spectrometry easily distinguished organic and chemical fertilizer treatments. However, for low-level application fertilizer treatments, this dual isotope approach became indistinguishable over time. Using a chemometric approach (combined isotope and elemental approach), organic and chemical fertilizer mixes and low-level applications of synthetic and organic fertilizers were detectable in B. chinensis and their associated soils, improving the detection limit beyond the capacity of individual isotopes or elemental characterization. LDA shows strong promise as an improved method to discriminate genuine organic Brassica vegetables from produce treated with chemical fertilizers and could be used as a robust test for organic produce authentication. PMID:27355562

  8. The source of natural and anthropogenic heavy metals in the sediments of the Minjiang River Estuary (SE China): implications for historical pollution.

    PubMed

    Xu, Yonghang; Sun, Qinqin; Yi, Liang; Yin, Xijie; Wang, Aijun; Li, Yunhai; Chen, Jian

    2014-09-15

    Two sedimentary cores in the Minjiang River estuary (SE China) are documented for grain size, clay minerals, heavy metals, magnetic parameters and Pb isotopes to investigate the source and historical variation of heavy metals. The MJK9 core was collected outside of the Minjiang River estuary, and the core is composed of mixed sediments, of which ~70% from the Yangtze River and 30% from the Minjiang River. It is thus difficult to be used for tracing the human activity along the Minjiang River. In contrast, the sediments of MJK16 core which was collected in a nearshore area are primarily from the Minjiang River. The enrichment factors of the sediments were <1.5, indicating minor pollution. The results indicate that the sediments of the MJK16 core have Cu and Pb concentrations increasing since 1980, associated with the increase of magnetic mineral concentration and (206)Pb/(207)Pb and (206)Pb/(208)Pb of the sediments. We compared the Pb isotopic compositions between our results and those for the deposit mining in the Minjiang River basin, and aerosols and coal dust in south China, and considered that Pb in the sediments of the MJK16 core was derived primarily from weathered rocks as well as industrial emission (e.g. coal combustion). The sediments have anthropogenic Pb concentrations ranging from 6% in 1950 to 23.7% in 2010, consistent with the impact of rapid urban and industrial development in China.

  9. Impact on the environment from steel bridge paint deterioration using lead isotopic tracing, paint compositions and soil deconstruction.

    PubMed

    Gulson, Brian; Chiaradia, Massimo; Davis, Jeffrey; O'Connor, Gary

    2016-04-15

    Deterioration and repair of lead paint on steel structures can result in contamination of the ambient environment but other sources of lead such as from past use of leaded paint and gasoline and industrial activities can also contribute to the contamination. Using a combination of high precision lead isotopic tracing, detailed paint examination, including with scanning electron microscopy, and soil deconstruction we have compared paint on a steel bridge and bulk soil and lead-rich particles separated from soil. The majority of Pb found in the paint derives from Australian sources but some also has a probable US origin. The isotopic data for the bulk soils and selected particles lie on a mixing line with end members the geologically ancient Broken Hill lead and possible European lead which is suggested to be derived from old lead paint and industrial activities. Data for gasoline-derived particulates lie on this array and probably contribute to soil Pb. Although paint from the bridge can be a source of lead in the soils, isotopic tracing, paint morphology and mineralogical identification indicate that other sources, including from paint, gasoline and industrial activities, are contributing factors to the lead burden. Even though physical characteristics and elemental composition are the same in some particles, the isotopic signatures demonstrate that the sources are different. Plots using (206)Pb/(208)Pb vs (206)Pb/(207)Pb ratios, the common representation these days, do not allow for source discrimination in this investigation.

  10. Trace-element and Sr, Nd, Pb, and O isotopic composition of Pliocene and Quaternary alkali basalts of the Patagonian Plateau lavas of southernmost South America

    USGS Publications Warehouse

    Stern, C.R.; Frey, F.A.; Futa, K.; Zartman, R.E.; Peng, Z.; Kurtis, Kyser T.

    1990-01-01

    The Pliocene and Quaternary Patagonian alkali basalts of southernmost South America can be divided into two groups. The "cratonic" basalts erupted in areas of Cenozoic plateau volcanism and continental sedimentation and show considerable variation in 87Sr/86Sr (0.70316 to 0.70512), 143Nd/144Nd (e{open}Nd) and 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios (18.26 to 19.38, 15.53 to 15.68, and 38.30 to 39.23, respectively). These isotopic values are within the range of oceanic island basalts, as are the Ba/La, Ba/Nb, La/Nb, K/Rb, and Cs/Rb ratios of the "cratonic" basalts. In contrast, the "transitional" basalts, erupted along the western edge of the outcrop belt of the Pliocene and Quaternary plateau lavas in areas that were the locus of earlier Cenozoic Andean orogenic arc colcanism, have a much more restricted range of isotopic composition which can be approximated by 87Sr/86Sr=0.7039??0.0004, e{open}Nd, 206Pb/204Pb=18.60??0.08, 207Pb/204Pb=15.60??0.01, and 208Pb/204Pb=38.50??0.10. These isotopic values are similar to those of Andean orogenic are basalts and, compared to the "cratonic" basalts, are displaced to higher 87Sr/86Sr at a given 143Nd/144Nd and to higher 207Pb/204Pb at a given 208Pb/204Pb. The "transitional" basalts also have Ba/La, Ba/Nb, La/Nb, and Cs/Rb ratios higher than the "cratonic" and oceanic island basalts, although not as high as Andean orogenic are basalts. In contrast to the radiogenic isotopes, ??18O values for both groups of the Patagonian alkali basalts are indistinguishable and are more restricted than the range reported for Andean orogenic are basalts. Whole rock ??18O values calculated from mineral separates for both groups range from 5.3 to 6.5, while measured whole rock ??18O values range from 5.1 to 7.8. The trace element and isotopic data suggest that decreasing degrees of partial melting in association with lessened significance of subducted slabderived components are fundamental factors in the west to east transition from arc

  11. Lead isotope constraints on the origin of andesite and dacite magmas at Tungurahua volcano (Ecuador)

    NASA Astrophysics Data System (ADS)

    Nauret, Francois; Ancellin, Marie-Anne; Vlastelic, Ivan; Tournigand, Pierre-Yves; Samaniego, Pablo; Le Pennec, Jean Luc; Gannoun, Mouhcine; Hidalgo, Silvana; Schiano, Pierre

    2016-04-01

    Understanding the occurrence of large explosive eruptions involving silica-rich magmas at mostly andesitic volcanoes is crucial for volcanic hazard assessment Here we focus on the well-known active Tungurahua volcano (Ecuador), specifically its eruptive sequence for the last 3000 years BP, which are characterized by VEI 3 explosive events involving mostly homogeneous andesitic compositions (56-59 wt.% SiO2). However, some large eruptions (VEI ≥ 4) involving andesitic and dacitic magmas (up to 66 wt.% SiO2) also occur at 3000 BP, 1250 BP and 1886 AD. An additional outburst of siliceous magmas occurred during the last eruptive eruption of this volcano in 2006 [1]. Volcanic products at Tungurahua are described as been generated by a binary mixing between a silica-rich and a silica-poor end-member, but the origin of these components was not discussed [2]. Major, trace elements and Sr-Nd-Pb isotopes were used to investigate the genesis of the andesites and dacites. Andesites are heterogeneous in terms of Pb isotopes (206Pb/204Pb: 18.189-19.154, 207Pb/204Pb:15.658-15.696, 208Pb/204Pb: 38.752-38.918, 207Pb/206Pb: 0.8240-0.8275) but homogeneous in terms of major-trace element. Dacite are characterized by homogenous and low 207Pb/206Pb (0.8235±0.0001), very low Nb/U (1.97 to 4.49) and Ce/Pb (2.52-2.99) and high Th/La ratios (0.24 to 0.49). Triangular distribution of data in major element or trace element ratio vs. Pb isotopes plots suggests that at least three components control geochemical variability at Tungurahua. We interpret andesite compositions as reflecting mainly a deep mixture of two mantle components, with small addition of crustal material. We suggest that dacite results from a mixing between various andesite compositions and a larger amount of a contaminant derived from the volcanic basement of the Tungurahua made of late Cretaceous to Palaeogene oceanic plateau basalts and volcano-sedimentary rocks volcanic. Since andesite and dacite occur during the same

  12. Petrogenesis of pegmatites and granites in southwestern Maine

    SciTech Connect

    Tomascak, P.B.; Walker, R.J.; Krogstad, E.J. . Dept. of Geology)

    1993-03-01

    Granitic pegmatites occurring near the town of Topsham in southwestern Maine are mineralogically diverse, featuring abundant dikes and contain rare earth element minerals as well as one pegmatite that contains Li minerals. The pegmatite series crops out near the Brunswick granite, a texturally diverse granitic pluton, and lies 13 km southeast of the Mississippian age Sebago batholith. Areas intruded by pegmatites that possess such different mineral assemblages are globally rare. The origins of these mixed'' pegmatite series have not been comprehensively investigated. There is no known pattern of regional zonation (mineral/chemical) among Topsham series pegmatites, hence simple fractionation processes are probably not responsible for the compositional variations. The authors are attempting to clarify pegmatite petrogenesis using common Pb isotopic ratios of feldspars and Sm-Nd isotopic data from whole rocks and minerals. Pb isotopic ratios from leached feldspars reflect the Pb ratios of the source from which they were derived. The range of Pb isotopic compositions of alkali feldspars from 7 granitic pegmatites is as follows: [sup 206]Pb/[sup 204]Pb = 18.5-19.1; [sup 207]Pb/[sup 204]Pb = 15.53-15.69; [sup 208]Pb/[sup 204]Pb = 38.3-38.6. The Brunswick granite has K-feldspars with [sup 206]Pb/[sup 204]Pb = 18.40-18.47, [sup 207]/[sup 204]Pb = 15.64-15.66 and [sup 208]Pb/[sup 204]Pb = 38.29-38.39. The Pb isotopic compositions of both pegmatites and granites are significantly more radiogenic than existing data for the Sebago granite and argue against the consanguinity of Topsham pegmatites and the Sebago batholith. These data instead support a genetic link between the pegmatites and the Brunswick granite, which ranges from a fine-grained two-mica granite to a garnet-bearing pegmatitic leucogranite.

  13. Source components and magmatic processes in the genesis of Miocene to Quaternary lavas in western Turkey: constraints from HSE distribution and Hf-Pb-Os isotopes

    NASA Astrophysics Data System (ADS)

    Aldanmaz, Ercan; Pickard, Megan; Meisel, Thomas; Altunkaynak, Şafak; Sayıt, Kaan; Şen, Pınar; Hanan, Barry B.; Furman, Tanya

    2015-08-01

    Hf-Pb-Os isotope compositions and highly siderophile element (HSE) abundance variations are used to evaluate the mantle source characteristics and possible effects of differentiation processes in lavas from western Turkey, where the eruption of Late Miocene to Quaternary OIB-type intraplate mafic alkaline lavas followed pre-Middle Miocene convergent margin-type volcanism. Concentrations of Os, Ir, and Ru (IPGE) in the OIB-type intraplate lavas decrease with fractionation for primitive melts (MgO > 10 wt%), suggesting that these elements reside predominantly in olivine and associated HSE retaining trace phases and behave compatibly during olivine-dominated fractionation. Fractional crystallization trends indicate distinctly lower bulk partition coefficients for IPGE in more evolved lavas, possibly reflecting a change in the fractionating assemblages. Pd and Re in the primitive melts display negative correlations with MgO, demonstrating moderately incompatible behavior of these elements during fractionation, while the significantly scattered variation in Pt against MgO may indicate the effects of micronuggets of a Pt-rich alloy. Os-rich alkaline primary lavas (>50 ppt Os) exhibit a limited range of 187Os/188Os (0.1361-0.1404), with some xenolith-bearing lavas displaying depletions in 187Os/188Os (0.1131-0.1232), suggesting slight compositional modification of primitive melts through contamination with highly depleted, Os-rich mantle lithosphere. More radiogenic Os isotope ratios (187Os/188Os > 0.1954) in the evolved lavas reflect contamination of the magmas by high187Os/188Os crustal material during shallow differentiation. The OIB-type lavas show limited variations in Hf and Pb isotopes with 176Hf/177Hf = 0.282941-0.283051, 206Pb/204Pb = 18.683-19.091, 207Pb/204Pb = 15.579-15.646, 208Pb/204Pb = 38.550-38.993; 176Hf/177Hf ratios correlate negatively with 208Pb*/206Pb*, suggesting the effects of similar mantle processes on the evolution of time-integrated Th/U and Lu

  14. Effects of weathering on the UPb ages of zircon from the Morton Gneiss, Minnesota

    USGS Publications Warehouse

    Stern, T.W.; Goldich, S.S.; Newell, M.F.

    1966-01-01

    Weathering has caused large losses of lead from the zircon in the residual clay derived from the Morton Gneiss of southwestern Minnesota, drastically reducing the 206Pb/238U and the 207Pb/235U ages. The 207Pb/206Pb age probably has not been significantly affected. Loss of lead by leaching during weathering has not been adequately considered in explanation of discordant ages of zircon. ?? 1966.

  15. Multiple tree-ring isotopes as environmental indicators of diffuse atmospheric pollution in a peri-urban area

    NASA Astrophysics Data System (ADS)

    Doucet, A.; Savard, M. M.; Bégin, C.; Ouarda, T. B.; Marion, J.

    2010-12-01

    The combined analyses of tree-ring δ13C, δ18O, δ15N, 206Pb/207Pb, 206Pb/204Pb and 206Pb/208Pb isotope ratios of three red spruce specimens from the Tantaré ecological reserve located 40 km northwest of Québec City (Canada) were studied with the aim of reconstructing environmental conditions and unravel past air-quality changes of the 1880-2007 period. To separate the tree-ring δ18O and δ13C patterns induced by natural conditions from those generated by anthropogenic perturbations, a linear regression was applied between the most explicative meteorological parameters and the isotopic series for the period of low pollution (1880 to 1909). The model equations were then applied to the most recent part of the series (1910-2007) to verify if climatic conditions have remained the main driver of the tree-ring isotopic variations. The good fit between the modeled and measured δ18O series for the entire studied period suggests that the assimilation of oxygen by red spruce trees is not significantly affected by pollution stress near Québec City. However, the deviation between the measured and modeled δ13C values for the 1944-2007 period indicates that diffuse pollution affected carbon assimilation by the investigated trees. To independently validate if atmospheric pollution could have generated the deviation between the measured and the estimated δ13C values, a linear regression was applied between the portion of the residual δ13C values and atmospheric pollution (Canadian fossil fuel proxy from 1958 to 2000). The nice fit between the modeled δ13C values from the combination of the two regression analyses based on climate and emission proxy strongly supports the hypothesis that there is a natural and an anthropogenic portion in the δ13C variations of the studied specimens. The short-term variations of the red spruce δ15N series are correlated with the instrumentally measured amounts of provincial N emissions for the 1990 to 2006 period (longest measurements

  16. Nuclear level densities in {sup 208}Bi and {sup 209}Po from the neutron spectra in the (p, n) reactions on {sup 208}Pb and {sup 209}Bi nuclei

    SciTech Connect

    Zhuravlev, B. V. Lychagin, A. A. Titarenko, N. N.; Demenkov, V. G.; Trykova, V. I.

    2010-07-15

    The spectra of neutrons from the (p, n) reactions on the {sup 208}Pb and {sup 209}Bi nuclei were measured in the proton-energy range 8-11 MeV. These measurements were performed by using a time-of-flight spectrometer of fast neutrons on the basis of the pulsed tandem accelerator EGP-15 of the Institute of Physics and Power Engineering (Obninsk, Russian Federation). A high resolution and stability of the time-of-flight spectrometermade it possible to identify reliably low-lying discrete levels alongwith the continuum section of the neutron spectra. The measured data were analyzed on the basis of the statistical equilibrium and preequilibrium models of nuclear reactions. The respective calculations were performed by using the precise formalism of Hauser-Feshbach statistical theory together with the generalized model of a superfluid nucleus and the back-shifted Fermi gas model for the nuclear-level density. The nuclear-level densities in {sup 208}Bi and {sup 209}Po were determined along with their energy dependencies and model parameters. Our results are discussed together with available experimental data and recommendations of model systematics.

  17. Lead-isotopic data from sulfide minerals from the Cascade Range, Oregon and Washington

    USGS Publications Warehouse

    Church, S.E.; LeHuray, A.P.; Grant, A.R.; Delevaux, M.H.; Gray, J.E.

    1986-01-01

    Lead-isotopic studies of mineral deposits associated with Tertiary plutons found in the Cascade Range of Oregon and Washington demonstrate a rather uniform isotopic composition in various sulfide minerals ( 206Pb 204Pb = 18.84 to 19.05; 207Pb 204Pb = 15.57 to 15.62; 208Pb 204Pb = 38.49 to 38.74), show less variation than data from the volcanic rocks of the Cascade Range and fall within the mixing array defined by the MORB regression line and continental sediments. An evaluation of the role of crustal assimilation by hydrothermal convection during emplacement was made on five sulfide deposits associated with a single composite batholith, the Cloudy Pass pluton. The Pb-isotopic data and mass balance calculations suggest that only minor amounts of the lead were derived from the overlying Precambrian (?) Swakane Biotite Gneiss during emplacement. The bulk of the metal that occurs in sulfide deposits in the Cascade mineral belt appears to have been derived from subducted continental detritus. The variation of the Pb-isotopic signature of Sulfides from specific districts or deposits suggests that there is a correlation with age and structure of the crust. 206Pb 204Pb is greater than 18.92 in northern Washington and southern Oregon where deposits have intruded Mesozoic or older crust. However, the ore deposits between the northern Oregon border and central Oregon, south of Eugene, have intruded younger crust composed largely of mafic and andesitic volcanic rocks and 206Pb 204Pb lies between 18.84 and 18.92. This region, previously called the Columbia embayment, appears to be underlain by Tertiary volcanic rocks. Lead-isotopic data may be used to define the boundaries between discontinuous blocks of Mesozoic crust and Tertiary volcanic cover. ?? 1986.

  18. Isotopic Studies of the Guerrero Composite Terrane, West-Central Mexico: Implications for Provenance of Crustal Rocks and Ore Metals

    NASA Astrophysics Data System (ADS)

    Potra, A.; Macfarlane, A. W.; Salters, V. J.; Sachi-Kocher, A.

    2010-12-01

    New Pb, Sr, and Nd isotope analyses of various crustal units and ores from the Guerrero terrane are presented in order to gain insight into their provenance. Mesozoic basement rocks from the Arteaga Complex and Tejupilco metamorphic suite contain radiogenic Pb relative to bulk earth models (206Pb/204Pb between 18.701 and 19.256, 207Pb/204Pb between 15.623 and 15.693, and 208Pb/204Pb between 38.694 and 39.216), plotting to the right of the average Pb crust evolution curve of Stacey and Kramers (1975). The isotopic compositions of Pb in these rocks are substantially more radiogenic than published data on high-grade metamorphic rocks from the Grenvillian-age Oaxaca terrane, but are similar to Paleozoic basement rocks of the Mixteca terrane. Sr and Nd isotope data suggest that the basement rocks of the Guerrero terrane partly originated from ocean-floor rocks which were overlain by sediments derived from a cratonic terrane, possibly represented by the metamorphic complexes of the Oaxaca or Mixteca terranes. Lead isotope ratios of Cretaceous sedimentary rocks of the Zihuatanejo and Huetamo Sequences define two different clusters, with the Zihuatanejo Sequence units shifted to more radiogenic values (206Pb/204 between 18.763 and 19.437, 207Pb/204Pb between 15.580 and 15.643, and 208Pb/204Pb between 38.510 and 38.892). Samples from the Huetamo Sequence are less radiogenic than the metamorphic basement, with Pb isotope ratios between 18.630 and 18.998 for 206Pb/204, 15.563 and 15.641 for 207Pb/204Pb, and 38.369 and 38.610 for 208Pb/204Pb. They plot close to the radiogenic end of the MORB field, suggesting a possible mixing line between the basement rocks and the MORB component. Lead isotope ratios of Tertiary intrusive rocks from La Verde, El Malacate, and La Esmeralda resemble the orogene reservoir in the plumbotectonics model of Zartman and Doe (1981). Plutonic rocks from La Verde show the most radiogenic Pb compositions, suggesting a significant influence of old

  19. Tracking atmospheric sulphur pollution from the study of Racomitrium lanuginosum mosses in Iceland: A multi-isotope approach (δ34S, 206Pb/204Pb, δ13C and δ15N)

    NASA Astrophysics Data System (ADS)

    Proust, E.; Widory, D.; Gautason, B.; Rogers, K.; Morrison, J.

    2010-12-01

    Among terrestrial plants, the applicability of mosses as monitoring organisms of atmospheric pollutants is a world-wide accepted technique due to their special biological and morphologic characteristics as nonvascular plants. They are commonly regarded as the best bioindicators of air quality because they can accumulate sulphur (S) and other elements to a far greater level than is necessary for their physiological needs. This study aims at using different isotope systematics δ34S, 206Pb/204Pb, δ13C and δ15N) to help understand the origin of S in the atmophsere of Reykjavik and its vicinity, and especially the potential contribution of surrounding geothermal plants. The selected Icelandic woolly fringe moss (Racomitrium lanuginosum (Hedw.) Brid.) is extremely common in lava fields and gravely and stony areas. Samples were taken in four distinct sampling sites around the city of Reykjavik: Bláfjöll area (south-eastern suburb of the city), and close to three power plants: Hellisheioarvirkjun (northern suburb of the city), Svartsengi (south-western suburb of the city) and Nesjavellir (north-eastern suburb of the city). Results show that, whatever the sampling context is, S is controlled by a binary mixing, between i) a high δ34S (around 16‰) end-member, characteristic of mosses from Hellisheioarvirkjun, and ii) a low δ34S (around -2‰) end-member, characteristic of mosses from Nesjavellir. The multi-isotope approach, confirms this binary relation and helps to constrain the different end-members involved.

  20. Two-types of Early Cretaceous adakitic porphyries from the Luxi terrane, eastern North China Block: Melting of subducted Paleo-Pacific slab and delaminated newly underplated lower crust

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Xu, Zhaowen; Lu, Xiancai; Fu, Bin; Lu, Jianjun; Yang, Xiaonan; Zhao, Zengxia

    2016-01-01

    The origin and tectonic setting of Early Cretaceous adakitic rocks from the Luxi terrane in the eastern North China Block (NCB) remain debated. To resolve this issue, we determined whole-rock geochemistry, zircon U-Pb ages, and in situ Hf-O isotopes of the Mengyin and Liujing adakitic porphyries from the Luxi terrane. Zircon U-Pb dating results reveal that both the Mengyin and Liujing plutons were emplaced during the Early Cretaceous, with weighted mean 206Pb/238U ages of 130 ± 1 Ma (2σ) and 131 ± 2 Ma (2σ), respectively. In addition, abundant Neoarchean-Paleoproterozoic inherited zircon cores are identified in the Mengyin adakitic porphyry with 207Pb/206Pb ages ranging from 2.53 to 2.42 Ga. Rocks of both plutons are silicic (SiO2 = 65.4-70.2 wt.%), metaluminous, and alkaline in composition, comprising mainly quartz syenite porphyries. Samples from both plutons are enriched in large ion lithophile elements (LILEs) (e.g., Rb, Sr, and Ba), and light rare earth elements (LREEs), depleted in high field strength elements (HFSEs) (e.g., Nb, Ta, and Ti), and heavy rare earth elements (HREEs), and have either positive or no Eu anomalies. In addition, both adakitic porphyries have high Mg# values (51-64), high Sr and La contents, low Y and Yb contents, and high Sr/Y (Mengyin = 149-264; Liujing = 58-110) and (La/Yb)N (Mengyin = 32.4-45.3; Liujing = 43.8-53.1) ratios, similar to adakitic rocks worldwide. The Mengyin adakitic porphyry has higher whole-rock εNd(t) values (-5.8 to - 4.1), more radiogenic Pb [(206Pb/204Pb)i = 18.35-18.39, (207Pb/204Pb)i = 15.55-15.56, (208Pb/204Pb)i = 38.20-38.23], higher zircon rim εHf(t) values (+ 3.3 to + 8.8) and δ18O values (+ 6.5‰ to + 7.9‰), and lower (87Sr/86Sr)i ratios (0.7049-0.7050) than the Liujing adakitic porphyry [εNd(t) = - 12.4 to - 12.2, (206Pb/204Pb)i = 17.63-17.72, (207Pb/204Pb)i = 15.56-15.58, (208Pb/204Pb)i = 37.76-37.94, εHf(t) = - 14.8 to - 11.2, δ18O = + 5.9‰ to + 7.1‰, (87Sr/86Sr)i = 0.7090-0.7091]. The

  1. The lead isotope systematics of ophiolite complexes

    NASA Astrophysics Data System (ADS)

    Hamelin, Bruno; Dupré, Bernard; Allègre, Claude J.

    1984-03-01

    Samples of eleven ophiolites from the Mediterranean and the Pacific belts have been studied through Pb sbnd Pb systematics. The ophiolites studied show both isotopic variations within one sequence and differences between the various complexes. The intra-sequence isotopic variations result principally from the in situ decay of uranium and thorium since the formation of the ophiolites. μ ratios ( 238U/ 204Pb ) higher than 50 in the effusive part of ophiolites are required to explain the 206Pb/ 204Pb spread within the sequences, and such values are notably higher than those presently measured in the oceanic crust. This uranium enrichment with respect to lead is due to the combined effect of the magmatic fractionations and of chemical exchanges during marine alteration. Pb loss must be an important factor for the U/Pb increase. Since the 207Pb/ 204Pb ratio is not affected by recent radioactive decay, it represents a very useful tracer for the discussion of the genetic environment of the ophiolites. Three main types of Pb isotopic characteristics may be distinguished among ophiolite complexes, on the basis of their 207Pb/ 204Pb : - The ophiolite complexes of In Zecca (Corsica), Semail (Oman) and Toba (Japan) show 207Pb/ 204Pb similar to the least radiogenic present-day MORB. These complexes probably originated in regions geochemically comparable to the present-day depleted mantle. However, the Semail ophiolite has a higher 208Pb/ 204Pb ratio than MORB, which may be compatible with an origin in an interarc basin or premature arc. - The circum-Pacific ophiolites of Papua New Guinea, New Caledonia and Zambales (Philippines) have 207Pb/ 204Pb comparable to the present-day "transitional" portions of the ridges. - Finally the circum-Mediterranean ophiolites of Troodos, Vourinos, and Antalya, display 207Pb/ 204Pb ratios clearly higher than those of the present accretion zones. Thus, their genesis must have involved a significant continental component, and an origin in an

  2. Lead Isotopic Compositions of the Endeavour Sulfides, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Labonte, F.; Hannington, M. D.; Cousens, B. L.; Blenkinsop, J.; Gill, J. B.; Kelley, D. S.; Lilley, M. D.; Delaney, J. R.

    2006-12-01

    32 sulfide samples from the main structures of the Endeavour vent field, Juan de Fuca Ridge, were analyzed for their Pb isotope composition. The samples were collected from 6 main vent fields between 1985 and 2005 and encompass a strike length of more than 15 km along the ridge crest. The sulfides are typical of black smoker deposits on sediment-starved mid-ocean ridges. Pb isotope compositions of the massive sulfides within the six hydrothermal fields vary within narrow ranges, with 206Pb/204Pb = 18.58 18.75, 207Pb/204Pb = 15.45 15.53 and 208Pb/204Pb = 37.84 38.10. A geographic trend is observed, with the lower Pb ratios restricted mostly to the northern part of the segment (Salty Dawg, Sasquatch and High Rise fields), and the higher Pb ratios restricted mostly to the southern part of the segment (Main Endeavour, Clam Bed and Mothra fields). Variations within individual fields are much smaller than those between fields, and variation within individual sulfide structures is within the uncertainty of the measurements. Therefore, it is unlikely that the ranges of Pb isotope compositions along the length of the segment reflect remobilization, replacement, and recrystallization of sulfides, as suggested for the observed Pb isotope variability in some large seafloor sulfide deposits. Instead, the differences in isotopic compositions from north to south are interpreted to reflect differences in the source rocks exposed to hydrothermal circulation of fluids below the seafloor. Possible sources of the somewhat more radiogenic Pb may be small amounts of buried sediment, either from turbidites or from hemipelagic sediment. This possibility is supported by high concentrations of CH4 and NHC4 found in the high-temperature vent fluids at the Main Endeavour Field, which are interpreted to reflect subseafloor interaction between hydrothermal fluids and organic material in buried sediments. However, the majority of the samples fall below and are approximately parallel to the

  3. Sr-Nd-Pb isotope systematics and clinopyroxene-host disequilibrium in ultra-potassic magmas from Toro-Ankole and Virunga, East-African Rift: Implications for magma mixing and source heterogeneity

    NASA Astrophysics Data System (ADS)

    Muravyeva, N. S.; Belyatsky, B. V.; Senin, V. G.; Ivanov, A. V.

    2014-12-01

    Nd, Pb and Sr isotope ratios have been determined for kamafugite lava and clinopyroxene phenocrysts from Bunyaruguru (Toro-Ankole) and Virunga volcanic fields of the East African Rift. The whole rock Sr-Nd isotopic signatures of kamafugites (87Sr/86Sr: 0.70463-0.70536; 143Nd/144Nd: 0.51249-0.51255) suggest derivation from an EM1-type mantle source. In contrast, Pb isotopic compositions of the same samples (206Pb/204Pb: 19.00-19.57; 207Pb/204Pb: 15.69-15.74; 208Pb/204Pb: 39.30-40.26) reveal a similarity to EM2-type mantle. New Nd, Pb and Sr isotopic data for clinopyroxene (87Sr/86Sr: 0.70473-0.70503; 143Nd/144Nd: 0.51250-0.51254; 206Pb/204Pb: 18.04-18.17; 207Pb/204Pb: 15.58-15.60; 208Pb/204Pb: 38.09-38.23) suggest derivation from an EM1-like source, and indicate Sr and Pb isotope disequilibrium between clinopyroxene and corresponding host rock. Moreover, clinopyroxenes exhibiting a greater degree of isotopic disequilibrium with their host rock are more sodic in composition. The isotopic disequilibrium is corroborated by the presence of chemical zoning within clinopyroxene, which suggests rapid magma ascent rates preventing melt homogenization. The Pb isotopic ratios for both mineral and corresponding whole rock, together with published data on East African rift-related alkaline centers, define a trend interpreted to represent a mixing line for melts derived from sources such as EM1 and as HIMU. The similar isotopic compositions for clinopyroxene from the different volcanic rocks within the East African Rift suggest the existence of a common, older mantle source for their parental melts. The origin of these melts can be attributed to an enrichment event ~ 400-500 Ma, i.e., significantly prior the younger ultrapotassic magmatism. Our preferred interpretation for the results reported here involves the mixing of melts derived from EM1- and HIMU-like sources, which were rapidly transported to the Earth's surface. The primary magmas formed as the result of melting of a

  4. Dust Deposition and Migration of the ITCZ through the Last Glacial Cycle in the Central Equatorial Pacific (Line Islands).

    NASA Astrophysics Data System (ADS)

    Reimi Sipala, M. A.; Marcantonio, F.

    2014-12-01

    Atmospheric dust can be used to record climate change in addition to itself playing a role in several key climate processes, such as affecting Earth's albedo, fomenting rain coalescence, encouraging biological productivity, and enhancing carbon export though particle sinks. Using deep sea sediments, it is possible to quantify and locate the sources and sinks of atmospheric dust. A key area of research is the shift in the inter-tropical converge zone (ITCZ), a thermally influenced area that shifts according to the northern and southern hemisphere temperature gradient. This ongoing project focuses on the changes of the ITCZ over the Central Equatorial Pacific (CEP) over the past ~25000 years. The research focuses on two cores taken from the Line Islands Ridge at 0° 29' N (ML1208-18GC), and 4° 41' N (ML1208-31BB). The main aim is to quantify the magnitude and provenance of windblown dust deposited in the CEP, and to address questions regarding the nature of the variations of dust through ice-age climate transitions. Radiogenic isotopes (Sr, Nd, Pb) have been successfully used to distinguish between different potential dust sources in the aluminosilicates fractions of Pacific Sediments. Our preliminary Pb isotope ratios suggest that, for modern deposition, the northern core's (31BB) detrital sediment fraction is likely sourced from Asian Loess (average ratios are 206Pb/204Pb = 18.88, 207Pb/204Pb = 15.69, 208Pb/204Pb = 39.06). The equatorial core's (18GC) detrital fraction has a less radiogenic Pb signature, which is consistent with South American dust sourcing (206Pb/204Pb = 18.62, 207Pb/204Pb = 15.63, 208Pb/204Pb = 38.62). This is indicative of a strong modern ITCZ that acts as an effective barrier for inter-hemispheric dust transport. Prior to Holocene time, the changes in Pb isotope ratios in both cores appear to be in anti-phase; the northern core becomes less radiogenic up to the LGM, while the southern core becomes more radiogenic. This is potentially due to a

  5. Pb and O isotopic constraints on the source of granitic rocks from Cape Breton Island, Nova Scotia, Canada

    USGS Publications Warehouse

    Ayuso, R.A.; Barr, S.M.; Longstaffe, F.J.

    1996-01-01

    Pb isotopic compositions of leached feldspars from twenty-three plutons in Cape Breton Island can be divided into two groups: anorthosite, syenite, and granite in the Blair River Complex, which have the least radiogenic compositions on the Island, and granitic rocks from terranes (Aspy, Bras d'Or, and Mira) to the south. Pb isotopic data for the Blair River Complex (206Pb/204Pb = 17.399-18.107; 207Pb/204Pb = 15.505-15.560; 208Pb/204Pb = 36.689-37.733) are consistent with an old source region ultimately derived from the mantle and contaminated by sialic crust. Oxygen isotopic compositions of syenite in the Blair River Complex (??18O = +8.0 to +8.5 permil) are slightly higher than anorthosite (+7.0 to +8.3 permil); a Silurian granite in the Blair River Complex has ??18O = +7.5 permil. Cambrian to Devonian plutons in the Aspy, Bras d'Or, and Mira terranes are more radiogenic (206Pb/204Pb = 18.192-18.981; 207Pb/204Pb = 15.574-15.712; 208Pb/ 204Pb =37.815-38.936) than the Blair River Complex and were generated from source regions having a predominant crustal Pb signature (high ??). The ??18O values of granites and granodiorites in the Aspy terrane (+7.5 to +9.2 permil; avg = +8.6 permil) and Bras d'Or (+3.7 to +11.3 permil; avg = +9.4 permil) are also consistent with involvement of sialic crust. Many Late Proterozoic granites from the Mira terrane have anomalously low ??18O values (+0.2 to +5.9 permil), perhaps produced from protoliths that had undergone hydrothermal alteration prior to melting. Paleozoic granitic rocks from the Aspy, Bras d'Or, and Mira terranes cannot be uniquely distinguished on the basis of their Pb and O isotopic compositions. The granitic rocks could have been generated during terrane amalgamation from combinations of unradiogenic (Grenville-like) and more radiogenic (Avalon-like) sources.

  6. Inter-Tropical Convergence Zone Shifts During the Last Glacial Cycle Near the Line Islands Ridge.

    NASA Astrophysics Data System (ADS)

    Reimi Sipala, M. A.; Marcantonio, F.

    2015-12-01

    This research focuses on the shift in the inter-tropical convergence zone (ITCZ) during the last glacial cycle. Deep sea sediments from the Central Equatorial Pacific (CEP) are used to quantify and isolate the sources and sinks of atmospheric dust. Dust records and influences climate affecting a wide range of process from Earth's Albedo to carbon export. Our aim is to determine the provenance of windblown dust deposited in the CEP near the Line Islands Ridge using radiogenic Nd and Pb isotopes, and to infer the location of the ITCZ and the changes of atmospheric transport through ice-age climate transitions. We focus on three cores from the CEP, along a meridional transect at approximately 160° W --- 0° 28' N (ML1208-17PC), 4° 41' N (ML1208-31BB), and 7 ° 2'N (ML1208-31BB). Radiogenic isotopes (Sr, Nd, Pb) have been successfully used to distinguish between different potential dust sources in the aluminosilicates fractions of Pacific Sediments. Our preliminary data suggest that the equatorial core (17PC) predominantly receives its dust from South America and South American volcanics South America (206Pb/204Pb = 18.62, 207Pb/204Pb = 15.63, 208Pb/204Pb = 38.62; ; ɛNd = ~ -5). The middle core, which more closely reflects the modern position of the ITCZ, has varied dust provenance through time, at times consistent with Asian Loess (average ratios are 206Pb/204Pb = 18.88, 207Pb/204Pb = 15.69, 208Pb/204Pb = 39.06; ɛNd = ~ -7) and Asian Volcanics (ɛNd = ~-1) suggesting a shift in the ITCZ south of 4N before the LGM. Our results for the most northern core are forthcoming. Prior to Holocene time, the changes in Pb isotope ratios in both cores appear to be in anti-phase; the northern core becomes less radiogenic up to the LGM, while the southern core becomes more radiogenic. This is potentially due to a weakening of the ITCZ during glacial times. A secondary aim of this work is to determine if the ITCZ migrated further south than core 17PC during Heinrich stage II.

  7. Geological, fluid inclusion and isotopic studies of the Yinshan Cu-Au-Pb-Zn-Ag deposit, South China: Implications for ore genesis and exploration

    NASA Astrophysics Data System (ADS)

    Wang, Guo-Guang; Ni, Pei; Wang, Ru-Cheng; Zhao, Kui-Dong; Chen, Hui; Ding, Jun-Ying; Zhao, Chao; Cai, Yi-Tao

    2013-09-01

    The Yinshan Cu-Au-Pb-Zn-Ag deposit is located in Dexing, South China. Ore bodies are primarily hosted in low-grade phyllite of the Neoproterozoic Shuangqiaoshan Group along EW- and NNW-striking fault zones. Pb-Zn-Ag mineralization is dictated by Jurassic rhyolitic quartz porphyries (ca. 172 Ma), whereas Cu-Au mineralization is associated with Jurassic dacite porphyries (ca. 170 Ma). The main ore minerals are pyrite, chalcopyrite, galena, sphalerite, tetrahedrite-tennatite, gold, silver, and silver sulphosalt, and the principal gangue minerals are quartz, sericite, calcite, and chlorite. Two-phase liquid-rich (type I), two-phase vapor-rich (type II), and halite-bearing (type III) fluid inclusions can be observed in the hydrothermal quartz-sulfides veins. Type I inclusions are widespread and have homogenization temperatures of 187-303 °C and salinities of 4.2-9.5 wt.% NaCl equivalent in the Pb-Zn-Ag mineralization, and homogenization temperatures of 196-362 °C and salinities of 3.5-9.9 wt.% NaCl equivalent in the Cu-Au mineralization. The pervasive occurrence of type I fluid inclusions with low-moderate temperatures and salinities implies that the mineralizing fluids formed in epithermal environments. The type II and coexisting type III inclusions, from deeper levels below the Cu-Au ore bodies, share similar homogenization temperatures of 317-448 °C and contrasting salinities of 0.2-4.2 and 30.9-36.8 wt.% NaCl equivalent, respectively, which indicates that boiling processes occurred. The sulfur isotopic compositions of sulfides (δ34S = -1.7‰ to +3.2‰) suggest a homogeneous magmatic sulfur source. The lead isotopes of sulfides (206Pb/204Pb = 18.01-18.07; 207Pb/204Pb = 15.55-15.57; and 208Pb/204Pb = 38.03-38.12) are consistent with those of volcanic-subvolcanic rocks (206Pb/204Pb = 18.03-18.10; 207Pb/204Pb = 15.56-15.57; and 208Pb/204Pb = 38.02-38.21), indicating a magmatic origin for lead in the ore. The oxygen and hydrogen isotope compositions (δ18O = +7.8

  8. CONCH: A Visual Basic program for interactive processing of ion-microprobe analytical data

    NASA Astrophysics Data System (ADS)

    Nelson, David R.

    2006-11-01

    A Visual Basic program for flexible, interactive processing of ion-microprobe data acquired for quantitative trace element, 26Al- 26Mg, 53Mn- 53Cr, 60Fe- 60Ni and U-Th-Pb geochronology applications is described. Default but editable run-tables enable software identification of secondary ion species analyzed and for characterization of the standard used. Counts obtained for each species may be displayed in plots against analysis time and edited interactively. Count outliers can be automatically identified via a set of editable count-rejection criteria and displayed for assessment. Standard analyses are distinguished from Unknowns by matching of the analysis label with a string specified in the Set-up dialog, and processed separately. A generalized routine writes background-corrected count rates, ratios and uncertainties, plus weighted means and uncertainties for Standards and Unknowns, to a spreadsheet that may be saved as a text-delimited file. Specialized routines process trace-element concentration, 26Al- 26Mg, 53Mn- 53Cr, 60Fe- 60Ni, and Th-U disequilibrium analysis types, and U-Th-Pb isotopic data obtained for zircon, titanite, perovskite, monazite, xenotime and baddeleyite. Correction to measured Pb-isotopic, Pb/U and Pb/Th ratios for the presence of common Pb may be made using measured 204Pb counts, or the 207Pb or 208Pb counts following subtraction from these of the radiogenic component. Common-Pb corrections may be made automatically, using a (user-specified) common-Pb isotopic composition appropriate for that on the sample surface, or for that incorporated within the mineral at the time of its crystallization, depending on whether the 204Pb count rate determined for the Unknown is substantially higher than the average 204Pb count rate for all session standards. Pb/U inter-element fractionation corrections are determined using an interactive log e-log e plot of common-Pb corrected 206Pb/ 238U ratios against any nominated fractionation-sensitive species pair

  9. Clinopyroxene-host disequilibrium (Sr-Nd-Pb isotope systematics) in ultra-potassic magmas from East-African Rift: Implications for magma mixing and source heterogeneity

    NASA Astrophysics Data System (ADS)

    Muravyeva, Natalya; Belyatsky, Boris; Senin, Valeriy

    2014-05-01

    Nd, Pb and Sr isotope ratios have been determined for kamafugite lava and clinopyroxene and phlogopite phenocrysts from Toro-Ankole and Virunga volcanic fields of the East African Rift. The whole rock Sr - Nd isotopic signatures of kamafugites (87Sr/86Sr: 0.70463 - 0.70536; 143Nd/144Nd: 0.51249 - 0.51255) suggest derivation from an EM1-type mantle source. In contrast, Pb isotopic compositions of the same samples (206Pb/204Pb: 19.00 - 19.57; 207Pb/204Pb: 15.69 - 15.74; 208Pb/204Pb: 39.30 - 40.26) reveal a similarity to EM2-type mantle. New Nd, Pb and Sr isotopic data for clinopyroxene (87Sr/86Sr: 0.70473 - 0.70503; 143Nd/144Nd: 0.51250 - 0.51254; 206Pb/204Pb: 18.04 - 18.17; 207Pb/204Pb: 15.58 - 15.60; 208Pb/204Pb: 38.09 - 38.23) suggest derivation from an EM1-like source, and indicate Sr and Pb isotope disequilibrium between clinopyroxene and corresponding host rock. Moreover, clinopyroxenes demonstrating a greater degree of isotopic disequilibrium with their host rock are more sodic in composition. The isotopic disequilibrium is corroborated by the presence of chemical zoning within clinopyroxene, which suggests rapid magma ascent rates preventing melt homogenization. The Pb isotopic ratios for both mineral and corresponding whole rock, together with published data on East African rift-related alkaline centers, define a trend interpreted to represent a mixing line for melts derived from sources such as EM1 and as HIMU. The similar isotopic compositions for clinopyroxene from the different volcanic rocks within the East African Rift suggest the existence of a common, older mantle source for their parental melts. The origin of these melts can be attributed to an enrichment event ~ 400-500 Ma, i.e., significantly prior the younger (Quaternary) ultrapotassic magmatism. Our preferred interpretation for the results reported here involves the mixing of the melts derived from EM1- and HIMU-like sources, which were rapidly transported to the Earth's surface. The primary

  10. Pb isotope geochemistry of Piton de la Fournaise historical lavas

    NASA Astrophysics Data System (ADS)

    Vlastélic, Ivan; Deniel, Catherine; Bosq, Chantal; Télouk, Philippe; Boivin, Pierre; Bachèlery, Patrick; Famin, Vincent; Staudacher, Thomas

    2009-07-01

    between the two major refilling events of March 1986 and February 2005 (0.28 km 3) could provide a realistic estimate of the magma reservoir size. Unradiogenic anomalies appear to be linked, more or less directly, to the eruption of olivine-rich lavas. The related samples have low 206Pb/ 204Pb and 208Pb/ 204Pb but normal 207Pb/ 204Pb, suggesting a recent decrease of U/Pb and Th/Pb, for instance through sequestration of Pb into sulfides. Olivine and sulfides, which are both denser than silicate melts, could be entrained with magma pulses, which give rise to high-flux oceanite eruptions.

  11. Lead Isotope Constraints on the Sources of Ore Metals in SW Mexican Deposits

    NASA Astrophysics Data System (ADS)

    Potra, A.; Macfarlane, A. W.

    2007-12-01

    the field defined by the sedimentary rocks. Whereas the metamorphic and igneous rocks analyzed so far plot generally above the Stacey-Kramers (1975) reference line, the ores and sedimentary rocks define a narrow field just below this line. The distribution of data from these ores on co-variation diagrams also appears to define a steep array, suggesting a MORB-EPR source contaminated with a 207Pb- and 208Pb-rich component (possibly the metamorphic basement or a sedimentary component). The analyzed sedimentary rocks are less radiogenic than the metamorphic basement, suggesting they are not simply derived from the basement and that other rocks were involved in their provenance.

  12. Source of lead in Central American and Caribbean mineralization, II. Lead isotope provinces

    NASA Astrophysics Data System (ADS)

    Cumming, George L.; Kesler, Stephen E.; Krstic, Dragan

    1981-12-01

    In an earlier study of Mesozoic and Cenozoic mineralization in Central America and the Caribbean region, we found that lead isotopic compositions of deposits in northern Central America, which is underlain by a pre-Mesozoic craton, ranged to higher 206Pb/ 204Pb and 207Pb/ 204Pb compositions than did deposits from elsewhere in the region, where the basement is Mesozoic oceanic material. Using 16 analyses for 12 new deposits, as well as new analyses for 11 of the samples studied previously, we have found that lead isotopic compositions correlate closely with crustal type but show little or no correlation with depth to the M-discontinuity. The deposits are divisible into three main groups including (in order of increasing 207Pb/ 204Pb and 208Pb/ 204Pb ratio): (1) deposits in southern Central America and all deposits in the Greater Antilles except Cuba; (2) all deposits in northern Central America; and (3) the Cuban deposits. Southern Central American and Caribbean lead is higher in 207Pb/ 204Pb and 208Pb/ 204Pb than most mid-ocean ridge basalts but could have been derived directly or indirectly from undepleted mantle. Northern Central America can be divided into the Maya block, which belongs to the Americas plate, and the Chortis block, which belongs to the Caribbean plate. Maya block deposits fall along a linear array whereas those of the Chortis block (except the Monte Cristo deposit) form a cluster. These results suggest that the Maya block is underlain by crust or mantle with a large range of U/Pb and Th/U ratios, whereas the Chortis block basement is more homogeneous. Two-stage model calculations indicate an age of about 2280±310 m.y. for the Maya block basement, although no such rocks are known in the region. Comparison of the Chortis block data to our recently published lead isotopic analyses of Mexican deposits shows considerable similarities suggesting that the Chortis block could have been derived from Mexico.

  13. A lead isotope study of mineralization in the Saudi Arabian Shield

    USGS Publications Warehouse

    Stacey, J.S.; Doe, B.R.; Roberts, R.J.; Delevaux, M.H.; Gramlich, J.W.

    1980-01-01

    New lead isotope data are presented for some late Precambrian and early Paleozoic vein and massive sulfide deposits in the Arabian Shield. Using the Stacey Kramers (1975) model for lead isotope evolution, isochron model ages range between 720 m.y. and 420 m.y. Most of the massive sulfide deposits in the region formed before 680 m.y. ago, during evolution of the shield. Vein type mineralization of higher lead content occurred during the Pan African event about 550 m.y. ago and continued through the Najd period of extensive faulting in the shield that ended about 530 m.y. ago. Late post-tectonic metamorphism may have been responsible for vein deposits that have model ages less than 500 m.y. Alternatively some of these younger model ages may be too low due to the mineralizing fluids acquiring radiogenic lead from appreciably older local crustal rocks at the time of ore formation. The low207Pb/204Pb ratios found for the deposits in the main part of the shield and for those in north-eastern Egypt, indicate that the Arabian craton was formed in an oceanic crustal environment during the late Precambrian. Involvement of older, upper-crustal material in the formation of the ore deposits in this part of the shield is precluded by their low207Pb/204Pb and208Pb/204Pb characteristics. In the eastern part of the shield, east of longitude 44??20???E towards the Al Amar-Idsas fault region, lead data are quite different. They exhibit a linear207Pb/204Pb-206Pb/204Pb relationship together with distinctly higher208Pb/204Pb characteristics. These data imply the existence of lower crustal rocks of early Proterozoic age that apparently have underthrust the shield rocks from the east. If most of the samples we have analyzed from this easterly region were mineralized 530 m.y. ago, then the age of the older continental rocks is 2,100??300 m.y. (2??). The presence of upper crustal rocks, possibly also of early Proterozoic age, is indicated by galena data from Hailan in South Yemen and also

  14. Stable lead isotopes reveal a natural source of high lead concentrations to gasoline-contaminated groundwater

    USGS Publications Warehouse

    Landmeyer, J.E.; Bradley, P.M.; Bullen, T.D.

    2003-01-01

    Concentrations of total lead as high as 1,600 ??g/L were detected in gasoline-contaminated and uncontaminated groundwater at three gasoline-release sites in South Carolina. Total lead concentrations were highest in turbid groundwater samples from gasoline-contaminated and uncontaminated wells, whereas lower turbidity groundwater samples (collected using low-flow methods) had lower total lead concentrations. Dissolved lead concentrations in all wells sampled, however, were less than 15 ??g total lead/L, the current United States Environmental Protection Agency (US EPA) maximum contaminant level (MCL). Because many total lead concentrations exceeded the MCL, the source of lead to the groundwater system at two of the three sites was investigated using a stable lead isotope ratio approach. Plots of the stable isotope ratios of lead (Pb) in groundwater as 207Pb/206Pb versus 208Pb/206Pb, and 208Pb/204Pb versus 206Pb/204Pb were similar to ratios characteristic of lead-based minerals in local rocks of the southeastern US, and were not similar to the stable lead isotopes ratios characteristic of distant lead ore deposits such as Broken Hill, Australia, used to produce tetraethyl lead in gasoline products prior to its phase-out and ban in the United States. Moreover, the isotopic composition of dissolved lead was equivalent to the isotopic composition of total lead in turbid samples collected from the same well, suggesting that the majority of the lead detected in the groundwater samples was associated with sediment particulates of indigenous aquifer material, rather than lead associated with spilled leaded gasoline. The results of this investigation indicate that (1) lead detected at some gasoline-release sites may be derived from the local aquifer material, rather than the gasoline release, and consequently may affect site-specific remediation goals; (2) non-low flow groundwater sampling methods, such as a disposable bailer, may result in turbid groundwater samples and

  15. Correlated Nd, Sr and Pb isotope variation in Walvis Ridge basalts and implications for the evolution of their mantle source

    NASA Astrophysics Data System (ADS)

    Richardson, S. H.; Erlank, A. J.; Duncan, A. R.; Reid, D. L.

    1982-07-01

    Basement intersected in DSDP holes 525A, 528 and 527 on the Walvis Ridge consists of submarine basalt flows and pillows with minor intercalated sediments. These holes are situated on the crest and mid and lower northwest flank of a NNW-SSE-trending ridge block which would have closely paralleled the paleo mid-ocean ridge [13, 14]. The basalts were erupted approximately 70 m.y. ago, an age equivalent to that of immediately adjacent oceanic crust in the Angola Basin and consistent with formation at the paleo mid-ocean ridge [14]. The basalt types vary from aphyric quartz tholeiites on the ridge crest to highly plagioclase phyric olivine tholeiites on the ridge flank. These show systematic differences in incompatible trace element and isotopic composition. Many element and isotope ratio pairs form systematic trends with the ridge crest basalts at one end and the highly phyric ridge flank basalts at the other. The low 143Nd/ 144Nd (0.51238), 206Pb/ 204Pb (17.54), 208Pb/ 204Pb (15.47), 208Pb/ 204Pb (38.14) and high 87Sr/ 86Sr (0.70512) ratios of the ridge crest basalts suggest derivation from an old Nd/Sm-, Rb/Sr- and Pb/U-enriched mantle source. This isotopic signature is similar to that of alkaline basalts on Tristan de Cunha but offset to significantly lower Nd and Pb isotopic ratios. The isotopic ratio trends may be extrapolated beyond the ridge flank basalts with higher 143Nd/ 144Nd (0.51270), 206Pb/ 204Pb (18.32), 207Pb/ 204Pb (15.52), 208Pb/ 204Pb (38.77) and lower 87Sr/ 86Sr (0.70417) ratios in the direction of increasingly Nd/Sm-, Rb/Sr- and Pb/U-depleted source compositions. These isotopic correlations are equally consistent with mixing od depleted and enriched end member melts or partial melting of an inhomogenous, variably enriched mantle source. However, observe Zr sbnd Ba sbnd Nb sbnd Y interelement relationships are inconsistent with any simple two-component model of magma mixing, as might result from the rise of a lower mantle plume through the upper

  16. Petrogenesis of synorogenic diorite-granodiorite-granite complexes in the Damara Belt, Namibia: Constraints from U-Pb zircon ages and Sr-Nd-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Jung, S.; Kröner, A.; Hauff, F.; Masberg, P.

    2015-01-01

    The synorogenic Palmental complex (central Damara Belt, Nambia) consists of ca. 545 Ma old quartz diorites and rare granodiorites and ca. 520 Ma-old leucogranites, representing one of the earliest and most primitive phase of crustal plutonism predating the main high-T regional metamorphism. Most quartz diorites and one granodiorite evolved through multistage, polybaric evolutionary processes involving fractionation from a lithospheric mantle-derived melt, followed by fractional crystallization of mainly hornblende, plagioclase and apatite which is shown by decreasing MgO, FeO, CaO, TiO2 and P2O5 with increasing SiO2. Assimilation of felsic basement gneisses was also important during formation of these granitoids. Although their chemical characteristics (high LILE, low HFSE) resemble those of quartz diorites and granodiorites with calc-alkaline affinity, they differ in their enriched Sr (initial 87Sr/86Sr: 0.7061-0.7098) and Nd (initial εNd: -2.7 to -9.9) isotopic composition. Neodymium depleted mantle mean crustal residence ages range from 1.3 to 1.9 Ga for the quartz diorites including the granodiorite. These model ages correlate with major and trace element abundances, further substantiating that AFC processes modified the initial isotopic systematics. Lead (206Pb/204Pb: 17.43-17.68, 207Pb/204Pb: 15.61-15.66, 208Pb/204Pb: 38.19-38.49) isotopic composition are unradiogenic relative to other Damaran intrusive rocks but plot above the Stacey and Kramers (1975) reference line, indicating that the source underwent an ancient (pre Pan-African) increase in U/Pb and Th/U, followed by more recent U-depletion. Some variation in 206Pb/204Pb at high 207Pb/204Pb further indicates involvement of ancient crustal material, most likely through AFC processes. A cross-cutting leucogranite dyke has also evolved isotopic compositions (initial 87Sr/86Sr: 0.7326; initial εNd: -15.6; 206Pb/204Pb: 17.42, 207Pb/204Pb: 15.62, 208Pb/204Pb: 38.16) but in view of the apparent younger age of

  17. Lead atmospheric deposition rates and isotopic trends in Asian dust during the last 9.5 kyr recorded in an ombrotrophic peat bog on the eastern Qinghai-Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Ferrat, Marion; Weiss, Dominik J.; Dong, Shuofei; Large, David J.; Spiro, Baruch; Sun, Youbin; Gallagher, Kerry

    2012-04-01

    A full understanding of the atmospheric Pb cycle in Asia during the Holocene is key to palaeoclimate studies of past atmospheric circulation patterns, as well as to assess the impact of increasing industrial activities in this region. However, long-term records of atmospheric Pb isotopic trends in Asia are still sparse. Consequently, we study changes in the concentrations, fluxes and isotopic signature of deposited Pb contained in a 14C-dated peat core from the eastern Qinghai-Tibetan Plateau, dating back to 9.5 kyr BP, and present the first peat record of the changing isotopic composition of atmospheric Pb in dust in Asia during this time. Lead concentrations and fluxes vary between 2.96-21.58 μg g-1 and 0.06-3.52 mg m-2 y-1, respectively, with an average Pb baseline of 6.80 ± 4.18 μg g-1. These values agree with other Pb studies of lake and peat archives in China but are one order of magnitude larger than early and mid-Holocene values measured in Europe. Lead isotopic variability throughout the core is small, varying between 206Pb/207Pb = 1.190-1.197, 206Pb/204Pb = 18.648-18.786, 207Pb/204Pb = 15.666-15.694 and 208Pb/204Pb = 38.890-39.090. The application of Bayesian trans-dimensional changepoint modelling to the Pb dataset enabled the identification of eight significant changes in the isotopic composition of the deposited Pb. Such changes mark different phases of atmospheric Pb deposition, and hence variations in atmospheric circulation patterns and environmental conditions. Temporal variations in the potential natural and/or anthropogenic Pb sources are assessed based on the 206Pb, 207Pb, 208Pb and 204Pb isotopic composition and the 1/[Pb] ratio of the peat samples. Our results suggest that Pb deposition throughout the Holocene was governed by local deposition and long-range input from natural dust sources in northwestern (Taklamakan desert and Qaidam basin) and northern China (Badain Jaran and Tengger deserts). Input from the northern sources seems to have

  18. Geological, rare earth elemental and isotopic constraints on the origin of the Banbanqiao Zn-Pb deposit, southwest China

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zhou, Jia-Xi; Huang, Zhi-Long; Yan, Zai-Fei; Bao, Guang-Ping; Sun, Hai-Rui

    2015-11-01

    The newly discovered Banbanqiao Zn-Pb deposit in the southeastern part of the Sichuan-Yunnan-Guizhou (SYG) Pb-Zn metallogenic province is located on the western Yangtze Block, southwest China. Ore bodies of the Banbanqiao deposit are stratiform type, host in dolomitic limestone and dolostone of the Lower Carboniferous Dapu Formation and occur within the NNE-trending Banbanqiao anticline. More than 1.5 million tones (Mt) Zn-Pb ores at grades of 0.26-10.32 wt.% Pb and 0.81-28.8 wt.% Zn have been controlled until now. δ13CPDB and δ18OSMOW values of calcite separates range from -2.8‰ to -0.7‰ (average -1.1‰) and +14.1‰ to +17.0‰ (average +15.5‰), respectively. The δ13CPDB values are similar to those of marine carbonate rocks, but higher than those of mantle and significantly different from those of sedimentary organic matter. However, the δ18OSMOW values are among those of mantle, marine carbonate rocks and sedimentary organic matter. δ34SCDT values of sulfide separates range from +3.2‰ to +9.9‰ (average +6.5‰), unlike mantle-derived sulfur (0 ± 3‰), whilst lower than evaporites (+22‰ to +28‰) within host strata. 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values of country shale and dolostone whole-rock samples are 18.47, 15.66 and 38.70, and 18.44-18.60, 15.66-15.85 and 38.70-39.14, respectively. Sulfide separates have 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values ranging from 18.03 to 18.73, 15.65 to 15.78 and 38.15 to 39.14, respectively. These Pb isotopic data indicate a clearly crustal source of Pb in the plot of 207Pb/204Pb vs. 206Pb/204Pb. Total REE (ΣREE) contents of country shale and dolostone whole-rock samples are 2.63 ppm and 0.72-86.2 ppm with δEu values are 2.79 and 0.34-0.70, respectively. Pyrite, sphalerite, galena and calcite samples have ΣREE contents of 5.3-36.4 ppm, 0.29-3.39 ppm, 0.52 ppm and 22.0-41.1 ppm, respectively, and δEu values of 0.64-0.86, 0.94-2.86, 0.32 and 0.21-0.45, respectively. These rare earth

  19. Isotope evolution in the HIMU reservoir beneath St. Helena: Implications for the mantle recycling of U and Th

    NASA Astrophysics Data System (ADS)

    Hanyu, Takeshi; Kawabata, Hiroshi; Tatsumi, Yoshiyuki; Kimura, Jun-Ichi; Hyodo, Hironobu; Sato, Keiko; Miyazaki, Takashi; Chang, Qing; Hirahara, Yuka; Takahashi, Toshiro; Senda, Ryoko; Nakai, Shun'ichi

    2014-10-01

    HIMU (high-μ; 238U/204Pb) is a mantle reservoir that has been thought to form by subduction and subsequent storage of ancient oceanic crust and lithosphere in the mantle. In order to constrain the processes that acted on subducted materials over several billion years, we present precise Pb-Sr-Nd-Hf-He isotopic data together with 40Ar/39Ar and K/Ar ages of HIMU lavas from St. Helena in the Atlantic. Clinopyroxene separates were analyzed together with whole-rock samples to better describe the geochemical characteristics of the HIMU component. Although isotopic variations are small in the St. Helena lavas (20.6-21.0 for 206Pb/204Pb) between 12 and 8 Ma, the younger lavas have more HIMU-like isotopic compositions than the older lavas. The mixing arrays defined by these lavas are remarkably similar to those observed in HIMU lavas from Austral Islands in the Pacific, suggesting that the two HIMU reservoirs located in different mantle domains are characterized by similar isotopic compositions with radiogenic 206Pb/204Pb and 208Pb/204Pb, enriched Nd and Hf isotopes, depleted Sr isotopes, and radiogenic 3He/4He. However, there is a significant difference between the St. Helena and Austral Islands lavas in 207Pb/204Pb. The St. Helena lavas show systematically higher 207Pb/204Pb for a given 206Pb/204Pb. Lead isotope evolution models suggest that both HIMU reservoirs formed around 2 Ga; however, the HIMU reservoir for St. Helena is about 0.3 Ga older than that for Austral Islands. The relation between 206Pb/204Pb and 208Pb/204Pb could reflect the time-integrated κ (232Th/238U) in the components. The HIMU components for St. Helena and Austral Islands have κ values between 3.3 and 3.7, which are intermediate between the present-day fresh mid-ocean ridge basalts (MORB; 2.6-3.2) and the chondritic silicate Earth (∼4). This is consistent with the model that the HIMU precursor is subducted oceanic crust created around 2 Ga from depleted upper mantle, in which κ monotonously

  20. Rb-Sr whole-rock and mineral ages, K-Ar, 40Ar/39Ar, and U-Pb mineral ages, and strontium, lead, neodymium, and oxygen isotopic compositions for granitic rocks from the Salinian Composite Terrane, California:

    USGS Publications Warehouse

    Kistler, R.W.; Champion, D.E.

    2001-01-01

    This report summarizes new and published age and isotopic data for whole-rocks and minerals from granitic rocks in the Salinian composite terrane, California. Rubidium-strontium whole-rock ages of plutons are in two groups, Early Cretaceous (122 to 100 Ma) and Late Cretaceous (95 to 82 Ma). Early Cretaceous plutons occur in all granitic rock exposures from Bodega Head in the north to those from the Santa Lucia and Gabilan Ranges in the central part of the terrane. Late Cretaceous plutons have been identified in the Point Reyes Peninsula, the Santa Lucia and the Gabilan Ranges, and in the La Panza Range in the southern part of the terrane. Ranges of initial values of isotopic compositions are 87Sr/86Sr, 0.7046-0.7147, δ18O, +8.5 to +12.5 per mil, 206Pb/204Pb, 18.901-19.860, 207Pb/204Pb, 15.618-15.814, 208Pb/204Pb, 38.569- 39.493, and εNd, +0.9 to -8.6. The initial 87Sr/86Sr=0.706 isopleth is identified in the northern Gabilan Range and in the Ben Lomond area of the Santa Cruz Mountains, in Montara Mountain, in Bodega Head, and to the west of the Farallon Islands on the Cordell Bank. This isotopic boundary is offset about 95 miles (160km) by right-lateral displacements along the San Gregorio-Hosgri and San Andreas fault systems.

  1. Lead isotopes reveal different sources of lead in balsamic and other vinegars.

    PubMed

    Ndung'u, Kuria; Hibdon, Sharon; Véron, Alain; Flegal, A Russell

    2011-06-15

    Fifty-eight brands of balsamic vinegars were analyzed for lead concentrations and isotopic compositions ((204)Pb, (206)Pb, (207)Pb, and (208)Pb) to test the findings of a previous study indicating relatively high levels of lead contamination in some of those vinegars--more than two thirds (70%) of them exceeded California's State Maximum Level (34 μg/L) based on consumption rates ≥0.5 μg Pb per day. The lead isotopic fingerprints of all those vinegars with high lead concentrations were then found to be primarily anthropogenic. This isotopic analysis unquestionably reveals multiple contamination sources including atmospheric pollutant Pb and an unidentified contamination source, likely occurring after grape harvest. Organically grown grape vinegars display the same Pb content and isotopic signatures as other vinegars. This implies that pesticides might not be a significant source of pollutant Pb in vinegars. A significant post-harvest contamination would be inherited from chemicals added during production and/or material used during transport, processing or storage of these vinegars. This is consistent with the highest Pb levels being found in aged vinegars (112±112 μg/L) in contrast to other vinegars (41.6±28.9 μg/L) suggesting contamination during storage. It is, therefore, projected that lead levels in most vinegars, especially aged balsamic and wine vinegars, will decrease with improvements in their manufacture and storage processes consequential to recent concerns of elevated levels of lead in some vinegars.

  2. Variations in lead isotopic abundances in Sprague-Dawley rat tissues: possible reason of formation.

    PubMed

    Liu, Duojian; Wu, Jing; Ouyang, Li; Wang, Jingyu

    2014-01-01

    It has been reported in previous research that the lead isotopic composition of blood, urine and feces samples statistically differed from the given lead sources in Sprague-Dawley (SD) rats. However, the reason for this phenomenon is still unclear. An animal experiment was performed to investigate the lead isotope fractionation in diverse biological samples (i.e., lungs, liver, kidneys, bone) and to explore the possible reasons. SD rats were intratracheally instilled with lead acetate at the concentrations of 0, 0.02, 0.2, and 2 mg/kg body weight. Biological samples were collected for lead isotope analysis using an inductively coupled plasma mass spectrometry (ICP-MS). Significant differences are observed in lead isotope abundances among the diverse biological samples. The lead isotope abundances ((206)Pb, (207)Pb and (208)Pb) in diverse biological samples show different degrees and directions of departure from the given lead source. The results suggest that differences in enrichment or depletion capacity for each lead isotope in the various tissues might lead to the variation in lead isotopic abundances in tissues. Moreover, a nonlinear relationship between the blood lead level and the lead isotope abundances in liver and bone is observed. When the whole-blood level is higher than 50 ng/mL, the lead isotopic compositions of biological samples tend to be the same. Thus, the data support the speculation of a fractionation functional threshold.

  3. Determination of trace element concentrations and stable lead, uranium and thorium isotope ratios by quadrupole-ICP-MS in NORM and NORM-polluted sample leachates.

    PubMed

    Mas, J L; Villa, M; Hurtado, S; García-Tenorio, R

    2012-02-29

    This work focuses on the monitoring of the potential pollution in scenarios that involve NORM-related industrial activities (environmental or in-door scenarios). The objective was to develop a method to determine extent and origin of the contamination, suitable for monitoring (i.e. simple, fast and economical) and avoiding the use of too many different instruments. It is presented a radiochemical method that allows the determination of trace element concentrations and 206Pb/207Pb/208Pb, 238U/234U and 232Th/230Th isotope ratios using a single sample aliquot and a single instrument (ICP-QMS). Eichrom UTEVA® extraction chromatography minicolumns were used to separate uranium and thorium in sample leachates. Independent ICP-MS determinations of uranium and thorium isotope ratios were carried out afterwards. Previously a small aliquot of the leachate was used for the determination of trace element concentrations and lead isotope ratios. Several radiochemical arrangements were tested to get maximum performances and simplicity of the method. The performances of the method were studied in terms of chemical yields of uranium and thorium and removal of the potentially interfering elements. The established method was applied to samples from a chemical industry and sediments collected in a NORM-polluted scenario. The results obtained from our method allowed us to infer not only the extent, but also the sources of the contamination in the area.

  4. Lead and strontium isotope data for thermal waters of the regional geothermal system in the Twin Falls and Oakley areas, South-Central Idaho

    SciTech Connect

    Mariner, R.H.; Young, H.W.

    1995-12-31

    Thermal fluids obviously related to aquifers in both rhyolite and limestone occur in the Twin Falls-Oakley area of south-central Idaho. Limestone-related waters (high calcium with low silica and fluoride) occur in the middle and upper (southern) parts of the area. Rhyolite-related waters (low calcium but high in silica and fluoride) occur in the lower (northern) part of the area. The relation of thermal fluids in Paleozoic limestone to thermal fluids in Tertiary rhyolite is unknown. Thermal fluids from limestone are dilute, so water-rock reaction in rhyolite could obliterate chemical evidence of fluid residence in a limestone. However, isotopic tracers such as {sup 206}Pb/{sup 204}Pb, {sup 207}Pb/{sup 204}Pb, {sup 208}Pb/{sup 204}Pb, and {sup 87}Sr/{sup 86}Sr might preserve evidence of fluid residence in limestone. Systematic relations between these isotopes and dissolved constituents in the water demonstrate the presence of limestone beneath most if not all of the study area and that aquifers in the limestone and rhyolite are hydrologically connected.

  5. Coupling of Uranium and Thorium Series Isotope Systematics for Age Determination of Late Pleistocene Zircons using LA-ICP-MS

    NASA Astrophysics Data System (ADS)

    Sakata, S.; Hirakawa, S.; Iwano, H.; Danhara, T.; Hirata, T.

    2014-12-01

    Zircon U-Th-Pb dating method is one of the most important tools for estimating the duration of magmatism by means of coupling of uranium, actinium and thorium decay series. Using U-Pb dating method, its reliability is principally guaranteed by the concordance between 238U-206Pb and 235U-207Pb ages. In case of dating Quaternary zircons, however, the initial disequilibrium effect on 230Th and 231Pa should be considered. On the other hands, 232Th-208Pb dating method can be a simple but powerful approach for investigating the age of crystallization because of negligible influence from initial disequilibrium effect. We have developed a new correction model for accurate U-Pb dating of the young zircon samples by taking into consideration of initial disequilibrium and a U-Pb vs Th-Pb concordia diagram for reliable age calibration was successfully established. Hence, the U-Th-Pb dating method can be applied to various zircons ranging from Hadean (4,600 Ma) to Quaternary (~50 ka) ages, and this suggests that further detailed information concerning the thermal history of the geological sequences can be made by the coupling of U-Th-Pb, fission track and Ar-Ar ages. In this presentation, we will show an example of U-Th-Pb dating for zircon samples from Sambe Volcano (3 to 100 ka), southwest Japan and the present dating technique using LA-ICP-MS.

  6. Lead concentration and isotopic composition in five peridotite inclusions of probable mantle origin

    USGS Publications Warehouse

    Zartman, R.E.; Tera, F.

    1973-01-01

    The lead content of five whole-rock peridotite inclusions (four lherzolites and one harzburgite) in alkali basalt ranges from 82 to 570 ppb (parts per billion). Approximately 30-60 ppb of this amount can be accounted for by analyzed major silicate minerals (olivine ??? 10 ppb; enstatite 5-28 ppb; chrome diopside ???400 ppb). Through a series of acid leaching experiments, the remainder of the lead is shown to be quite labile and to reside in either glassy or microcrystalline veinlets or accessory mineral phases, such as apatite and mica. The lead isotopic composition of the peridotites (206Pb/204Pb = 18.01-18.90; 207Pb/204Pb = 15.52-15.61; 208Pb/204Pb = 37.80-38.86) lies within the range of values defined by many modern volcanic rocks and, in particular, is essentially coextensive with the abyssal tholeiite field. In all but one instance, isotopic differences were found between the peridotite and its host alkali basalt. Two of the peridotites clearly demonstrated internal isotopic heterogeneity between leachable and residual fractions that could not simply be due to contamination by the host basalt. However, there is no evidence that these ultramafic rocks form some layer in the mantle with isotopic characteristics fundamentally different from those of the magma sources of volcanic rocks. ?? 1973.

  7. [High-precision in situ analysis of the lead isotopic composition in copper using femtosecond laser ablation MC-ICP-MS and the application in ancient coins].

    PubMed

    Chen, Kai-Yun; Fan, Chao; Yuan, Hong-Lin; Bao, Zhi-An; Zong, Chun-Lei; Dai, Meng-Ning; Ling, Xue; Yang, Ying

    2013-05-01

    In the present study we set up a femtosecond laser ablation MC-ICP-MS method for lead isotopic analysis. Pb isotopic composition of fifteen copper (brass, bronze) standard samples from the National Institute of Standards Material were analyzed using the solution method (MC-ICP-MS) and laser method (fLA-MC-ICPMS) respectively, the results showed that the Pb isotopic composition in CuPb12 (GBW02137) is very homogeneous, and can be used as external reference material for Pb isotopic in situ analysis. On CuPb12 112 fLA-MC-ICPMS Pb isotope analysis, the weighted average values of the Pb isotopic ratio are in good agreement with the results analyzed by bulk solution method within 2sigma error, the internal precision RSEs of the 208 Pb/204 Pb ratio and 207 Pb/206 Pb ratio are less than 90 and 40 ppm respectively, and the external precision RSDs of them are less than 60 and 30 ppm respectively. Pb isotope of thirteen ancient bronze coins was analyzed via fLA-MC-ICPMS, the results showed that the Pb isotopic composition of ancient coins of different dynasties is significantly different, and not all the Pb isotopic compositions in the coins even from the same dynasty are in agreement with each other.

  8. Variations in Lead Isotopic Abundances in Sprague-Dawley Rat Tissues: Possible Reason of Formation

    PubMed Central

    Liu, Duojian; Wu, Jing; Ouyang, Li; Wang, Jingyu

    2014-01-01

    It has been reported in previous research that the lead isotopic composition of blood, urine and feces samples statistically differed from the given lead sources in Sprague-Dawley (SD) rats. However, the reason for this phenomenon is still unclear. An animal experiment was performed to investigate the lead isotope fractionation in diverse biological samples (i.e., lungs, liver, kidneys, bone) and to explore the possible reasons. SD rats were intratracheally instilled with lead acetate at the concentrations of 0, 0.02, 0.2, and 2 mg/kg body weight. Biological samples were collected for lead isotope analysis using an inductively coupled plasma mass spectrometry (ICP-MS). Significant differences are observed in lead isotope abundances among the diverse biological samples. The lead isotope abundances (206Pb, 207Pb and 208Pb) in diverse biological samples show different degrees and directions of departure from the given lead source. The results suggest that differences in enrichment or depletion capacity for each lead isotope in the various tissues might lead to the variation in lead isotopic abundances in tissues. Moreover, a nonlinear relationship between the blood lead level and the lead isotope abundances in liver and bone is observed. When the whole-blood level is higher than 50 ng/mL, the lead isotopic compositions of biological samples tend to be the same. Thus, the data support the speculation of a fractionation functional threshold. PMID:24587048

  9. Lead isotopes in lichen transplants around a Cu smelter in Russia determined by MC-ICP-MS reveal transient records of multiple sources.

    PubMed

    Spiro, B; Weiss, D J; Purvis, O W; Mikhailova, I; Williamson, B J; Coles, B J; Udachin, V

    2004-12-15

    Transplants of the lichen Hypogymnia physodes, which is relatively tolerant to SO2 and heavy metals, were deployed for 3 months over a 60 km long SW-NE transect centered on a highly polluting Cu smelter and its adjoining town of Karabash, southern Urals, Russia. The abundance of 206Pb, 207Pb, 208Pb, and 204Pb were determined by MC-ICP-MS. The measurement of 204Pb revealed critical features, which would otherwise remain concealed: (i) The precise isotope ratios referenced to 204Pb allowed several different sources to be resolved even within the small area covered: (a) the obvious pollutant source of the Karabash Cu smelter; (b) two dispersed sources, likely to include soil with lower and different contributions of thorogenic and uranogenic lead; and (c) one anthropogenic source with higher contribution of 235U derived Pb. (ii) In part of the transect, the Pb isotope composition changed while the Pb concentrations remained the same. This indicates that the Pb content of the transplantation material from the background site was largely replaced and that the transplants provide a transient record reflecting a continuous accumulation and loss of environmental Pb, probably mainly in the form of extracellular particles. Overall, the method of lichen transplantation coupled with Pb isotope ratio determinations proved effective in assessing the usefulness of lichens in biomonitoring and in resolving different sources of atmospheric deposition.

  10. Stable isotope identification of lead sources in preschool children--the Omaha Study.

    PubMed

    Angle, C R; Manton, W I; Stanek, K L

    1995-01-01

    The objective was to determine, from analysis of the naturally occurring stable isotopes of lead, the relative contribution of food, handdust, housedust, soil and air lead to the absorbed (urinary) lead and the blood lead of children living in a former smelter city. A longitudinal 12 month study was conducted of 21 children, 2 - 3 years of age, living in central Omaha, balanced for race, gender and socioeconomic status. Field clean samples were collected monthly of 24 hour duplicate diet, handwipe and urine, with quarterly blood lead, annual environmental lead, weekly air for total lead and 206Pb, 207Pb and 208Pb by thermal ionization/mass spectrometry with a 205Pb spike in a Class II laboratory. Despite residence in a smelter city each child had a unique isotopic ratio of handwipe, blood and urine lead, the latter being identical. There was no correlation of handwipe isotopic ratio with proximity to a lead emission source or to the decade of the housing stock. The isotopic ratio of the annual mean handwipe lead predicted 43% of the variance of the annual mean blood and urine lead ratio (r2 = .43; p = .001). Handwipe lead ratios correlated (p < or = .05) with those of the windowsills and air ducts. The mean isotopic ratios of blood and urine lead were lower than those of handwipe and food, consistent with a contribution by endogenous bone lead. Clean catch urine provides a noninvasive index of blood lead isotopic ratio in children, as in adults.

  11. Enriched Nd-Sr-Pb isotopic signatures in the Dovyren layered intrusion ( eastern Siberia, Russia): Evidence for source contamination by ancient upper-crustal material

    USGS Publications Warehouse

    Amelin, Yu. V.; Neymark, L.A.; Ritsk, E. Yu; Nemchin, A.A.

    1996-01-01

    Major- and trace-element concentrations and Nd-, Sr- and Pb-isotopic ratios are reported for the Dovyren layered mafic-ultramafic intrusion in the northern Baikal region, eastern Siberia. Sm-Nd internal isochrons for an olivine gabbro from the layered series and a gabbronorite from a sill at the bottom of the Dovyren intrusion yield ages of 673 ?? 22 and 707 ?? 40 Ma, respectively. Initial isotopic ratios: 87Sr/86Sr (673) from 0.7101 to 0.7135, ??Nd(673 Ma) from - 16.3 to - 14.1, 206Pb/204Pb from 16.80 to 17.14, 207Pb/204Pb from 15.477 to 15.501 and 208Pb/204Pb from 37.17 to 37.59, are similar to those of late Archean-early Proterozoic upper continental crust, but do not appear to be a result of wallrock assimilation in the magma chamber. These isotopic features, as well as high K, Rb and LREE and low Ti concentrations in the calculated composition of the Dovyren parental magma, may be explained by subduction of sediments derived from upper continental crust into depleted mantle and subsequent melting of the metasomatized peridotite.

  12. Sources and characteristics of lead pollution in the urban environment of Guangzhou.

    PubMed

    Duzgoren-Aydin, Nurdan S

    2007-10-15

    Guangzhou, the capital of the southeastern province of Guangdong, is one of the largest and most rapidly developing industrial cities in China. In recent years its rapid economic development has brought great prosperity to the Pearl River Delta (PRD) region, but has also given rise to a wide variety of environmental problems. The current level of lead (Pb) contamination (75-926 mg/kg) in the surface environment of Guangzhou remains a major concern, even though the use of leaded petrol in the city was banned in 1997. The Pb isotope ratios (206Pb/207Pb(min-max) : 1.1612-1.1961 and 208Pb/207Pb(min-max) : 2.4495-2.4838) of the urban dusts from unconfined (road dusts and gully sediments) and relatively confined (vehicular tunnel) settings in Guangzhou remains in a relatively narrow range, comparable with those of the regional natural and anthropogenic sources. This study highlights the inherent shortcomings of the Pb isotope fingerprinting technique for provenancing Pb sources, as both the target media (urban dusts) and potential sources have similar and highly radiogenic Pb isotope values. This could not only lead to an overestimation of the effectiveness of phasing-out of leaded petrol, but also an underestimation of the ever-increasing relative contributions from other potential sources of pollution, including coal combustion, industrial emissions of local Pb-ores and non-additive Pb contents of crude oils. Re-suspended Pb-bearing particulates deposited from early vehicular exhaust emission of leaded petrol with distinctly low Pb isotope compositions are still an important source of Pb pollution in the region.

  13. Radiogenic Isotopes As Paleoceanographic Tracers in Deep-Sea Corals: Advances in TIMS Measurements of Pb Isotopes and Application to Southern Ocean Corals

    NASA Astrophysics Data System (ADS)

    Wilson, D. J.; van de Flierdt, T.; Bridgestock, L. J.; Paul, M.; Rehkamper, M.; Robinson, L. F.; Adkins, J. F.

    2014-12-01

    Deep-sea corals have emerged as a valuable archive of deep ocean paleoceanographic change, with uranium-series dating providing absolute ages and the potential for centennial resolution. In combination with measurements of radiocarbon, neodymium isotopes and clumped isotopes, this archive has recently been exploited to reconstruct changes in ventilation, water mass sourcing and temperature in relation to millennial climate change. Lead (Pb) isotopes in both corals and seawater have also been used to track anthropogenic inputs through space and time and to trace transport pathways within the oceans. Better understanding of the oceanic Pb cycle is emerging from the GEOTRACES programme. However, while Pb isotopes have been widely used in environmental studies, their full potential as a (pre-anthropogenic) paleoceanographic tracer remains to be exploited. In deep-sea corals, challenges exist from low Pb concentrations in aragonite in comparison to secondary coatings, the potential for contamination, and the efficient elemental separation required for measurement by thermal ionisation mass spectrometry (TIMS). Here we discuss progress in measuring Pb isotopes in coral aragonite using a 207Pb-204Pb double spike on a ThermoFinnigan Triton TIMS. For a 2 ng NIST-981 Pb standard, the long term reproducibility (using 1011 Ω resistors) is ~1000 ppm (2 s.d.) on 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios. We now show that using a new 1012 Ω resistor to measure the small 204Pb beam improves the internal precision on these ratios from ~500 ppm (2 s.e.) to ~250 ppm (2 s.e.) and we envisage a potential improvement in the long term reproducibility as a consequence. We further assess the internal precision and external reproducibility of our method using a BCR-2 rock standard and an in-house coral standard. Preliminary evidence on the application of this method to natural samples is derived from cleaning experiments and replication tests on deep-sea corals from the Southern

  14. Lead isotope ratios in six lake sediment cores from Japan Archipelago: Historical record of trans-boundary pollution sources.

    PubMed

    Hosono, Takahiro; Alvarez, Kelly; Kuwae, Michinobu

    2016-07-15

    Sediment cores from six lakes situated from north to south on the Japanese Archipelago were collected during 2009-2010 to investigate the hypothesis that deposition of lead (Pb) was coming from East Asia (including China, South Korea and eastern part of Russia). Accumulation rates and ages of the lake sediment were estimated by the (210)Pb constant rate of supply model and (137)Cs inputs to reconstruct the historical trends of Pb accumulation. Cores from four lakes located in the north and central Japan, showed clear evidence of Pb pollution with a change in the (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios in the recent sediment as compared to the deeper sediment. Among the six studied lakes, significant inputs of anthropogenic lead emissions were observed at Lake Mikazuki (north Hokkaido in north Japan), Lake Chokai (north of Honshu), and Lake Mikuriga (central part of Honshu). Pb isotopic comparison of collected core sediment and previously reported data for wet precipitation and aerosols from different Asian regions indicate that, before 1900, Pb accumulated in these three lakes was not affected by trans-boundary sources. Lake Mikazuki started to receive Pb emissions from Russia in early 1900s, and during the last two decades, this lake has been affected by trans-boundary Pb pollution from northern China. Lake Chokai has received Pb pollutant from northern China since early 1900s until 2009, whereas for the Lake Mikuriga the major Pb contaminant was transported from southern China during the past 100years. The results of our study demonstrate that Japan Archipelago has received trans-boundary Pb emissions from different parts of East Asian region depending on location, and the major source region has changed historically. PMID:27058126

  15. Atmospherically deposited trace metals from bulk mineral concentrate port operations.

    PubMed

    Taylor, Mark Patrick

    2015-05-15

    Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965 μg/m(2)/day) across all sites was more than 10-times the mean pre-play loadings (95 μg/m(2)/day). Maximum loading values after a 10-minute play period were 3012 μg/m(2), more than seven times the goal of 400 μg/m(2) used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404 μg/m(2)) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15 μg/m(2)/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes ((208)Pb/(207)Pb and (206)Pb/(207)Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are clear - even where operations are considered acceptable by managing authorities, targeted assessment and monitoring can be used to evaluate whether current management practices are truly best practice. Reassessment can identify opportunities for improvement and maximum environmental and human health protection. PMID:25706750

  16. Identification of contamination in a lake sediment core using Hg and Pb isotopic compositions, Lake Ballinger, Washington, USA

    USGS Publications Warehouse

    Gray, John E.; Pribil, Michael J.; Van Metre, Peter C.; Borrok, David M.; Thapalia, Anita

    2013-01-01

    Concentrations and isotopic compositions of Hg and Pb were measured in a sediment core collected from Lake Ballinger, near Seattle, Washington, USA. Lake Ballinger has been affected by input of metal contaminants emitted from the Tacoma smelter, which operated from 1887 to 1986 and was located about 53 km south of the lake. Concentrations and loadings of Hg and Pb in Lake Ballinger increased by as much as three orders of magnitude during the period of smelting as compared to the pre-smelting period. Concentrations and loadings of Hg and Pb then decreased by about 55% and 75%, respectively, after smelting ended. Isotopic compositions of Hg changed considerably during the period of smelting (δ202Hg = −2.29‰ to −0.38‰, mean −1.23‰, n = 9) compared to the pre-smelting period (δ202Hg = −2.91‰ to −2.50‰, mean −2.75‰, n = 4). Variations were also observed in 206Pb/207Pb and 208Pb/207Pb isotopic compositions during these periods. Data for Δ199Hg and Δ201Hg indicate mass independent fractionation (MIF) of Hg isotopes in Lake Ballinger sediment during the smelting and post-smelting period and suggest MIF in the ore smelted, during the smelting process, or chemical modification at some point in the past. Negative values for Δ199Hg and Δ201Hg for the pre-smelting period are similar to those previously reported for soil, peat, and lichen, likely suggesting some component of atmospheric Hg. Variations in the concentrations and isotopic compositions of Hg and Pb were useful in tracing contaminant sources and the understanding of the depositional history of sedimentation in Lake Ballinger.

  17. Pb-Sr-Nd isotopes in surficial materials at the Pebble Porphyry Cu-Au-Mo Deposit, Southwestern Alaska: can the mineralizing fingerprint be detected through cover?

    USGS Publications Warehouse

    Ayuso, Robert A.; Kelley, Karen D.; Eppinger, Robert G.; Forni, Francesca

    2013-01-01

    The Cretaceous Pebble porphyry Cu-Au-Mo deposit is covered by tundra and glacigenic sediments. Pb-Sr-Nd measurements were done on sediments and soils to establish baseline conditions prior to the onset of mining operations and contribute to the development of exploration methods for concealed base metal deposits of this type. Pebble rocks have a moderate range for 206Pb/204Pb = 18.574 to 18.874, 207Pb/204Pb = 15.484 to 15.526, and 208,Pb/204Pb = 38.053 to 38.266. Mineralized granodiorite shows a modest spread in 87Sr/86Sr (0.704354–0.707621) and 143Nd/144Nd (0.512639–0.512750). Age-corrected (89 Ma) values for the granodiorite yield relatively unradiogenic Pb (e.g., 207Pb/204Pb 87Sr/86Sr, and positive values of ɛNd (1.00–4.52) that attest to a major contribution of mantle-derived source rocks. Pond sediments and soils have similar Pb isotope signatures and 87Sr/86Sr and 143Nd/144Nd values that resemble the mineralized granodiorites. Glacial events have obscured the recognition of isotope signatures of mineralized rocks in the sediments and soils. Baseline radiogenic isotope compositions, prior to the onset of mining operations, reflect natural erosion, transport and deposition of heterogeneous till sheets that included debris from barren rocks, mineralized granodiorite and sulfides from the Pebble deposit, and other country rocks that pre- and postdate the mineralization events. Isotopic variations suggest that natural weathering of the deposit is generally reflected in these surficial materials. The isotope data provide geochemical constraints to glimpse through the extensive cover and together with other geochemical observations provide a vector to concealed mineralized rocks genetically linked with the Pebble deposit.

  18. Atmospherically deposited trace metals from bulk mineral concentrate port operations.

    PubMed

    Taylor, Mark Patrick

    2015-05-15

    Although metal exposures in the environment have declined over the last two decades, certain activities and locations still present a risk of harm to human health. This study examines environmental dust metal and metalloid hazards (arsenic, cadmium, lead and nickel) associated with bulk mineral transport, loading and unloading port operations in public locations and children's playgrounds in the inner city of Townsville, northern Queensland. The mean increase in lead on post-play hand wipes (965 μg/m(2)/day) across all sites was more than 10-times the mean pre-play loadings (95 μg/m(2)/day). Maximum loading values after a 10-minute play period were 3012 μg/m(2), more than seven times the goal of 400 μg/m(2) used by the Government of Western Australia (2011). Maximum daily nickel post-play hand loadings (404 μg/m(2)) were more than 26 times above the German Federal Immission Control Act 2002 annual benchmark of 15 μg/m(2)/day. Repeat sampling over the 5-day study period showed that hands and surfaces were re-contaminated daily from the deposition of metal-rich atmospheric dusts. Lead isotopic composition analysis of dust wipes ((208)Pb/(207)Pb and (206)Pb/(207)Pb) showed that surface dust lead was similar to Mount Isa type ores, which are exported through the Port of Townsville. While dust metal contaminant loadings are lower than other mining and smelting towns in Australia, they exceeded national and international benchmarks for environmental quality. The lessons from this study are clear - even where operations are considered acceptable by managing authorities, targeted assessment and monitoring can be used to evaluate whether current management practices are truly best practice. Reassessment can identify opportunities for improvement and maximum environmental and human health protection.

  19. Seven thousand years of records on the mining and utilization of metals from lake sediments in central China.

    PubMed

    Lee, Celine S L; Qi, Shi-Hua; Zhang, Gan; Luo, Chun-Ling; Zhao, Lu Y L; Li, Xiang-Dong

    2008-07-01

    A 268 cm section of sediment core from Liangzhi Lake in Hubei province in central China was used to assess the use and accumulation of metals in the lake in the past 7,000 years. The concentrations of trace metals, including Cu, Pb, Ni, and Zn, and major elements, Ca, Fe, and Mg, in a 14C- dated segment of sediment core were analyzed. Historical trends on the input of metals to Liangzhi Lake from around 5000 BC to the present were recorded in the sediments, representing about 7,000 years of history on the mining and utilization of metals in central China. The concentrations of Cu, Ni, Pb, and Zn increased gradually from about 3000 +/- 328 BC, indicating the start of the Bronze Age in ancient China. During the period 467 +/- 257 to 215 +/- 221 AD, there was a rapid increase in the concentrations of these metals in the sediments, indicating enormous inputs of these metals at that time. This era corresponded to China's Warring States Period (475- 221 BC) and the early Han Dynasty (206 BC-220 AD), during which copper and lead were extensively used in making bronze articles such as vessels, tools, and weapons. From 1880 +/- 35 AD to the early 1900s, there was also a significant increase in the concentrations of metals such as Cu, Ni, and Pb, which probably reflected the metal emissions and utilization during the early period of industrial development and weapon manufacture during the wars in China. The Pb isotopic analysis showed that the surface and subsurface sediments had lower 206Pb/207Pb and 208Pb/ 207Pb ratios than the deeper layers, reflecting the additional input of Pb from mining activities that took place during the Bronze Age era and in modern times. This study provides direct evidence of the environmental impact of the mining and utilization of metals in the last 7,000 years in one of the important regions of Chinese civilization.

  20. Selected organochlorine pesticides and polychlorinated biphenyls in atmosphere at Ruoergai high altitude prairie in eastern edge of Qinghai-Tibet Plateau and their source identifications

    NASA Astrophysics Data System (ADS)

    Gai, Nan; Pan, Jing; Tang, Hua; Tan, Ke-Yan; Chen, Da-Zhou; Zhu, Xiao-Hua; Lu, Guo-Hui; Chen, Shu; Huang, Yi; Yang, Yong-Liang

    2014-10-01

    Compared to the low-altitude areas, high-altitude regions have low air temperature and relatively high snow precipitation. These climatological characteristics will affect the environmental behavior of persistent organic pollutants (POPs) in such a special geographical environment, leading to cold-trapping of certain POPs in these areas. Ruoergai highland prairie in the eastern edge of the Qinghai-Tibetan Plateau was selected to study the distribution characteristics of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in aerosols and gas phase samples collected in two seasons of 2011 and measured by isotope dilution-HRGC/HRMS method. OCPs and PCBs in the Ruoergai air were at low levels compared with the adjacent populated areas such as Lanzhou and Chengdu. Higher concentrations of POPs in aerosol and gas phase were observed in winter than in summer, showing the impact of monsoon on the transport of POPs to this region. Northwesterly winds in winter may transport OCPs and PCBs from industrial and agricultural areas in the northwestern China. HCB, α-HCH, and PCB 28 were the predominant compounds found in the air. Soil to air fugacity ratios show that Ruoergai soils behave as a secondary source of the relatively volatile compounds (HCHs, α-endosulfan, PCB 28 and 52) to the atmosphere during summer and behave as a sink of atmospheric DDTs due to the OC-rich soils as well as lower temperatures. Similar 206Pb/207Pb and 208Pb/207Pb ratios in Ruoergai aerosols to those of aerosols of Lanzhou and ores in Qinghai, Xinjiang, Kazakhstan, and Russia may indicate that the aerosol sources were mainly related to air mass passing over the neighboring regions and countries.

  1. Environmental arsenic, cadmium and lead dust emissions from metal mine operations: Implications for environmental management, monitoring and human health.

    PubMed

    Taylor, Mark Patrick; Mould, Simon Anthony; Kristensen, Louise Jane; Rouillon, Marek

    2014-11-01

    Although blood lead values in children are predominantly falling globally, there are locations where lead exposure remains a persistent problem. One such location is Broken Hill, Australia, where the percentage of blood lead values >10 μg/dL in children aged 1-4 years has risen from 12.6% (2010), to 13% (2011) to 21% (2012). The purpose of this study was to determine the extent of metal contamination in places accessible to children. This study examines contemporary exposure risks from arsenic, cadmium, lead, silver and zinc in surface soil and dust, and in pre- and post-play hand wipes at six playgrounds across Broken Hill over a 5-day period in September 2013. Soil lead (mean 2,450 mg/kg) and zinc (mean 3,710 mg/kg) were the most elevated metals in playgrounds. Surface dust lead concentrations were consistently elevated (mean 27,500 μg/m(2)) with the highest lead in surface dust (59,900 μg/m(2)) and post-play hand wipes (60,900 μg/m(2)) recorded close to existing mining operations. Surface and post-play hand wipe dust values exceeded national guidelines for lead and international benchmarks for arsenic, cadmium and lead. Lead isotopic compositions ((206)Pb/(207)Pb, (208)Pb/(207)Pb) of surface dust wipes from the playgrounds revealed the source of lead contamination to be indistinct from the local Broken Hill ore body. The data suggest frequent, cumulative and ongoing mine-derived dust metal contamination poses a serious risk of harm to children.

  2. REE characteristics and Pb, Sr and Nd isotopic compositions of steel plant emissions.

    PubMed

    Geagea, M Lahd; Stille, P; Millet, M; Perrone, Th

    2007-02-01

    A comprehensive Pb-Sr-Nd isotope and REE tracer study of atmospheric trace metal pollution by a steel plant situated to the north of the urban communities of Strasbourg (France) and Kehl (Germany) has been performed using tree barks as biomonitors. The 206Pb/207Pb and 208Pb/207Pb isotopic ratios of the steel plant's filter dust are similar to values found in dust of waste incinerators. The 87Sr/86Sr ratio is similar to present-day ratios of Phanerozoic or Precambrian granitic rocks. The 143Nd/144Nd isotopic composition is very low and corresponds to an (Nd) value of -17.5. Such a low value is characteristic of old Precambrian granitic rocks and banded iron formations. Thus, this low (Nd) value might point to the origin of the iron necessary for the steel production. The fact, that this isotopic composition does not occur in crustal rocks of Western Central Europe makes the Nd isotope ratio a powerful tool to trace steel plants atmospheric emissions. The rare earth element (REE) distribution pattern of the steel plant's filter dust shows very specific fractionations like La and Nd enrichments which are traceable in tree barks over a distance of 4 km. The Pb, Sr and Nd isotope ratios not only enable the steel plant's emissions to be traced in a north-easterly direction, along the principal wind pathway but also enables the interference of this emission at 4 km NE from the steel plant with another atmospheric component originating from the Strasbourg Rhine harbour to be identified.

  3. Pb isotopic heterogeneity in basaltic phenocrysts

    SciTech Connect

    Bryce, Julia G.; DePaolo, Donald J.

    2002-06-01

    The Pb isotopic compositions of phenocrystic phases in young basaltic lavas have been investigated using the Getty-DePaolo method (Getty S. J. and DePaolo D. J. [1995] Quaternary geochronology by the U-Th-Pb method. Geochim. Cosmochim. Acta 59, 3267 3272), which allows for the resolution of small isotopic differences. Phenocryst, matrix, and whole rock analyses were made on samples from the 17 Myr-old Imnaha basalts of the Columbia River Group, a zero-age MORB from the Mid-Atlantic Ridge, and a ca. 260 kyr-old tholeiite from Mount Etna. Plagioclase feldspar phenocrysts have low-(U, Th)/Pb, and in each sample the plagioclase has significantly lower 206Pb/207Pb and 208Pb/207Pb values than whole rock, matrix, and magnetite-rich separates. The Pb isotopic contrast between plagioclase and matrix/whole rock is found in three samples with varying grain sizes (0.5 2 cm for the Imnaha basalt and MORB and <1 mm for the Etna sample) from different tectonic settings, suggesting that these results are not unique. The isotopic contrasts are only slightly smaller in magnitude than the variations exhibited by whole rock samples from the region. The Imnaha basalts also have Sr isotopic heterogeneity evident only in plagioclase phenocrysts, but the MORB and Etna lavas do not. The isotopic heterogeneities reflect magma mixing, and indicate that isotopically diverse magmas were mixed together just prior to eruption. The results reinforce indications from melt inclusion studies that magma source region isotopic heterogeneities have large amplitudes at short length scales, and that the isotopic variations imparted to the magmas are not entirely homogenized during segregation and transport processes.

  4. The Contribution of Trans-Pacific Submicron Aerosols and Local Particle Nucleation Bursts to California's Air Quality as Seen from the Pacific Coast Mountain Range

    NASA Astrophysics Data System (ADS)

    Asher, E. C. C.; Christensen, J. N.; Post, A.; Faloona, I. C.

    2015-12-01

    The long-range transport of dust and anthropogenic aerosols to the Western US has received considerable attention due to the growing disparity between North American and Asian air quality. Using MODIS and space-borne LIDAR measurements some have argued that the transcontinental transport of dust from Asia, Africa, and Europe outweighs that of locally produced combustion aerosols (Yu et al. 2012). This study seeks to compare the aerosol composition, number, and size distribution of locally derived submicron aerosols (including particle nucleation events) vs. long-range transported aerosols observed at a remote mountain site near the Pacific Coast. Toward this aim, rotating drum impactor (RDI) and scanning mobility particle size (SMPS) measurements of size-segregated elemental compositions and size spectra were collected from February to November of 2012 at Chews Ridge (elevation 1450 m) in Monterey County, California. This mountaintop site experiences two main wind modes. The main mode is ohshore-directed winds from the southwest, which are most likely to bring trans-Pacific aerosols to the site; and offshore-directed, northeasterly winds that bring continental aerosols to the site from the interior of California. Elemental ratios (normalized to Al), matrix factorization, and a k-cluster analysis of these data suggest distinct crustal, combustion, and marine sources with considerable seasonal as well as short-term variability. HYSPLIT model back trajectories support the hypothesized sources of these submicron aerosols. Locally, SMPS data reveal consistent nucleation bursts and subsequent growth in the 20-60 nm range during the afternoons. A distinct but weaker diel cycle was observed in the 70 - 100 nm range, corresponding to the smallest RDI impactor stage. Finally, the Pb isotopic composition (206Pb/207Pb and 208Pb/207Pb) of aerosol samples from selected dates will be measured by MC-ICPMS to further identify aerosol origins (e.g. Ewing et al. 2010).

  5. Application of laser ablation multicollector inductively coupled plasma mass spectrometry for the measurement of calcium and lead isotope ratios in packaging for discriminatory purposes.

    PubMed

    Santamaria-Fernandez, Rebeca; Wolff, Jean-Claude

    2010-07-30

    The potential of high-precision calcium and lead isotope ratio measurements using laser ablation coupled to multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) to aid distinction between four genuine and five counterfeit pharmaceutical packaging samples and further classification of counterfeit packaging samples has been evaluated. We highlight the lack of reference materials for LA-MC-ICP-MS isotope ratio measurements in solids. In this case the problem is minimised by using National Institute of Standards and Technology Standard Reference Material (NIST SRM) 915a calcium carbonate (as solid pellets) and NIST SRM610 glass disc for sample bracketing external standardisation. In addition, a new reference material, NIST SRM915b calcium carbonate, has been characterised in-house for Ca isotope ratios and is used as a reference sample. Significant differences have been found between genuine and counterfeit samples; the method allows detection of counterfeits and aids further classification of packaging samples. Typical expanded uncertainties for measured-corrected Ca isotope ratio values ((43)Ca/(44)Ca and (42)Ca/(44)Ca) were found to be below 0.06% (k = 2, 95% confidence) and below 0.2% for measured-corrected Pb isotope ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb). This is the first time that Ca isotope ratios have been measured in packaging materials using LA coupled to a multicollector (MC)-ICP-MS instrument. The use of LA-MC-ICP-MS for direct measurement of Ca and Pb isotopic variations in cardboard/ink in packaging has definitive potential to aid counterfeit detection and classification. PMID:20552700

  6. The petrogenesis of volcanics from Mt. Bulusan and Mt. Mayon in the Bicol arc, the Philippines

    NASA Astrophysics Data System (ADS)

    McDermott, Frank; , Francisco G. Delfin, Jr.; Defant, Marc J.; Turner, Simon; Maury, Rene

    2005-12-01

    Pliocene to recent volcanic rocks from the Bulusan volcanic complex in the southern part of the Bicol arc (Philippines) exhibit a wide compositional range (medium- to high-K basaltic-andesites, andesites and a dacite/rhyolite suite), but are characterised by large ion lithophile element enrichments and HFS element depletions typical of subduction-related rocks. Field, petrographic and geochemical data indicate that the more silicic syn- and post-caldera magmas have been influenced by intracrustal processes such as magma mixing and fractional crystallisation. However, the available data indicate that the Bicol rocks as a group exhibit relatively lower and less variable 87Sr/86Sr ratios (0.7036-0.7039) compared with many of the other subduction-related volcanics from the Philippine archipelago. The Pb isotope ratios of the Bicol volcanics appear to be unlike those of other Philippine arc segments. They typically plot within and below the data field for the Philippine Sea Basin on 207Pb/204Pb versus 206Pb/204Pb and 208Pb/204Pb versus 206Pb/204Pb diagrams, implying a pre-subduction mantle wedge similar to that sampled by the Palau Kyushu Ridge, east of the Philippine Trench. 143Nd/144Nd ratios are moderately variable (0.51285-0.51300). Low silica (<55 wt%) samples that have lower 143Nd/144Nd tend to have high Th/Nd, high Th/Nb, and moderately low Ce/Ce* ratios. Unlike some other arc segments in the Philippines (e.g. the Babuyan-Taiwan segment), there is little evidence for the involvement of subducted terrigenous sediment. Instead, the moderately low 143Nd/144Nd ratios in some of the Bicol volcanics may result from subduction of pelagic sediment (low Ce/Ce*, high Th/Nd, and high Th/Nb) and its incorporation into the mantle wedge via a slab-derived partial melt.

  7. The isotopic composition of lead in potassium feldspars from some 1.0-b.y. old North American igneous rocks

    USGS Publications Warehouse

    Zartman, R.E.; Wasserburg, G.J.

    1969-01-01

    The isotopic composition of lead and the uranium, thorium and lead concentrations in potassium feldspars are determined for more than 30 1.0-b.y. old North American igneous rocks. Samples representing a broad spectrum in petrographic type and mode of occurrence were chosen; an effort was made to include only rocks having well-documented ages from 950 to 1140 m.y. and showing minimal evidence of subsequent metamorphism. Most samples, including those from extensive terranes of contemporaneous age, have limited lead isotope variations ( Pb206 Pb204 = 16.74-17.38; Pb207 Pb204 = 15.39-15.59; Pb208 Pb204 = 36.38-37.10), which yield model ages close to the radiometric ages. Granite, pegmatite, and rhyolite from within the Grenville province of Canada and age-equivalent rocks of New York, Virginia, Texas, and Colorado and granophyric units associated with the Duluth Gabbro Complex of Minnesota are among the materials yielding this main isotopic spectrum. Several samples were encountered which had isotopic compositions very different from the above group. Lead showing a marked deficiency in radiogenic isotopes was found in two granitic bodies associated with older Labrador Trough rocks from Quebec, in a rapakivi granite from southern Nevada, and in a small granite stock from Mellen, Wisconsin. These occurrences all involve small intrusions of granite which lie near considerably older areas of basement rock. Model ages calculated from the Pb206 Pb204 ratio are older than the age of the intrusions and approach the age of the host basement rock. Several possible interpretations are offered to explain the isotopic behavior encountered in this study. In particular, a "vertically differentiated crust" model is proposed which will account for both the main spectrum and the anomalous lead. The significance of lead isotopic studies in understanding crustal structure in continental regions is discussed. ?? 1969.

  8. Application of laser ablation multicollector inductively coupled plasma mass spectrometry for the measurement of calcium and lead isotope ratios in packaging for discriminatory purposes.

    PubMed

    Santamaria-Fernandez, Rebeca; Wolff, Jean-Claude

    2010-07-30

    The potential of high-precision calcium and lead isotope ratio measurements using laser ablation coupled to multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) to aid distinction between four genuine and five counterfeit pharmaceutical packaging samples and further classification of counterfeit packaging samples has been evaluated. We highlight the lack of reference materials for LA-MC-ICP-MS isotope ratio measurements in solids. In this case the problem is minimised by using National Institute of Standards and Technology Standard Reference Material (NIST SRM) 915a calcium carbonate (as solid pellets) and NIST SRM610 glass disc for sample bracketing external standardisation. In addition, a new reference material, NIST SRM915b calcium carbonate, has been characterised in-house for Ca isotope ratios and is used as a reference sample. Significant differences have been found between genuine and counterfeit samples; the method allows detection of counterfeits and aids further classification of packaging samples. Typical expanded uncertainties for measured-corrected Ca isotope ratio values ((43)Ca/(44)Ca and (42)Ca/(44)Ca) were found to be below 0.06% (k = 2, 95% confidence) and below 0.2% for measured-corrected Pb isotope ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb). This is the first time that Ca isotope ratios have been measured in packaging materials using LA coupled to a multicollector (MC)-ICP-MS instrument. The use of LA-MC-ICP-MS for direct measurement of Ca and Pb isotopic variations in cardboard/ink in packaging has definitive potential to aid counterfeit detection and classification.

  9. [Lead isotope signatures and source identification in urban soil of Baoshan district, Shanghai].

    PubMed

    Dong, Chen-Yin; Zhang, Wei-Guo; Wang, Guan; Ma, Hong-Lei; Liu, Yuan; Liu, Ying; Ye, Lei-Ping; Yu, Li-Zhong

    2012-03-01

    Two soil cores were collected from the Yuepu Park and a vegetable field near the Yunchuan Road in Baoshan district, Shanghai. Particle size, Pb content and Pb stable isotopic ratios were measured to examine Pb contamination status and its source. The results indicate that Pb concentration in the vegetable field soil and Yuepu park soil varies from 17.2 mg x kg(-1) to 34.8 mg x kg(-1) and 17.5 mg x kg(-1) to 36. 5 mg x kg(-1), respectively. The observed Pb isotopic ratios of vegetable field samples vary from 0.827 to 0.849 for 207Pb/206Pb, and 2.082 to 2.101 for 208Pb/206Pb, while those of Yuepu Park samples range from 0.839 to 0.848 and 2.089 to 2.097, respectively. Pb content, its enrichment factor (EF) and Pb stable isotopic ratios increase upward in both soil cores. EF values of surfacial (top 10 cm) vegetable field samples and park samples are mostly greater than 1.5, suggesting that higher Pb contents in topsoils are caused by anthropogenic activities. Compared with previous reports on Pb isotope signatures of different environmental materials in Shanghai, Pb isotopic ratios in the two soil cores are between those of Yangtze River intertidal sediments and the dust of coal combustion, and those of soil samples with EF > 1.5 are closer to the isotopic ratios of coal combustion dust. It indicates that topsoil in the Baoshan district is contaminated by dust derived from coal combustion.

  10. Accumulation of atmospheric radionuclides and heavy metals in cryoconite holes on an Arctic glacier.

    PubMed

    Łokas, Edyta; Zaborska, Agata; Kolicka, Małgorzata; Różycki, Michał; Zawierucha, Krzysztof

    2016-10-01

    Surface of glaciers is covered by mineral and organic dust, together with microorganisms forming cryoconite granules. Despite fact that glaciers and ice sheets constitute significance part of land surface, reservoir of freshwater, and sites of high biological production, the knowledge on the cryoconite granules still remain unsatisfactory. This study presents information on radionuclide and heavy metal contents in cryoconites. Cryoconites collected from the Hans Glacier in SW Spitsbergen reveal high activity concentrations of anthropogenic ((238,239,240)Pu, (137)Cs, (90)Sr) and natural ((210)Pb) radionuclides. The (238)Pu/(239+240)Pu activity ratios in these cryoconites significantly exceed the mean global fallout ratio (0.025). The (238)Pu/(239+240)Pu ranged from 0.064 to 0.118. The (239+240)Pu/(137)Cs varied from 0.011 ± 0.003 to 0.030 ± 0.007. Such activity ratios as observed in these cryoconites were significantly higher than the values characterizing global fallout, pointing to possible contributions of these radionuclides from other sources. Heavy metals (Pb, Cd, Cu, Zn, Fe, and Mn) in cryoconites exceed both UCC concentrations and local rocks' concentrations, particularly for cadmium. The concentration ratios of stable lead isotopes ((206)Pb/(207)Pb, (208)Pb/(206)Pb) were determined to discriminate between the natural and anthropogenic sources of Pb in cryoconites and to confirm the strong anthropogenic contribution to heavy metal deposition in the Arctic. In investigated cryoconite holes, two groups of invertebrates, both extremophiles, Tardigrada and Rotifera were detected. Our study indicate that cryoconites are aggregates of mineral and organic substances on surfaces of glaciers are able to accumulate large amounts of airborne pollutants bound to extracellular polymeric substances secreted by microorganisms.

  11. Childhood lead exposure in an industrial town in China: coupling stable isotope ratios with bioaccessible lead.

    PubMed

    Li, Hong-Bo; Chen, Kai; Juhasz, Albert L; Huang, Lei; Ma, Lena Q

    2015-04-21

    Fingerprinting based on stable isotopes of lead (Pb) in blood and environmental media helps to identify Pb exposure pathways in children. However, previous studies used stable isotopes of total Pb in media. In this study, a wire rope production town in China (Zhuhang) was selected for investigating the effectiveness of using isotope ratios in bioaccessible Pb to identify childhood Pb exposure pathways. Blood Pb levels of 115 children in Zhuhang were 1.7-20.4 μg dL(-1), averaging 6.1 ± 3.2 μg dL(-1) (mean ± standard deviation), and were ∼1.6 times the national average in China (3.9 ± 1.8 μg dL(-1)). Among different environmental media (housedust, soil, PM10, vegetables, rice, and drinking water), housedust (695 ± 495 mg kg(-1)) and vegetables [0.36 ± 0.40 mg (kg of fresh weight)(-1)] contained elevated Pb concentrations. The isotope ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) of total Pb were the highest in housedust (0.8587 ± 0.0039 and 2.1049 ± 0.0087) but lower than blood Pb ratios (0.8634 ± 0.0027 and 2.1244 ± 0.0061). When using bioaccessible Pb in housedust (0.8639 ± 0.0018 and 2.1171 ± 0.0036), the isotope ratios overlapped with blood Pb ratios, suggesting that incidental ingestion of housedust was the predominant contributor to children's blood Pb. Coupling the stable isotope technique with bioaccessible Pb is more reliable for identifying Pb exposure pathways than total Pb determinations.

  12. Isotopes and Trace Elements as Natal Origin Markers of Helicoverpa armigera – An Experimental Model for Biosecurity Pests

    PubMed Central

    Holder, Peter W.; Armstrong, Karen; Van Hale, Robert; Millet, Marc-Alban; Frew, Russell; Clough, Timothy J.; Baker, Joel A.

    2014-01-01

    Protecting a nation's primary production sector and natural estate is heavily dependent on the ability to determine the risk presented by incursions of exotic insect species. Identifying the geographic origin of such biosecurity breaches can be crucial in determining this risk and directing the appropriate operational responses and eradication campaigns, as well as ascertaining incursion pathways. Reading natural abundance biogeochemical markers using mass spectrometry is a powerful tool for tracing ecological pathways as well as provenance determination of commercial products and items of forensic interest. However, application of these methods to trace insects has been underutilised to date and our understanding in this field is still in a phase of basic development. In addition, biogeochemical markers have never been considered in the atypical situation of a biosecurity incursion, where sample sizes are often small, and of unknown geographic origin and plant host. These constraints effectively confound the interpretation of the one or two isotope geo-location markers systems that are currently used, which are therefore unlikely to achieve the level of provenance resolution required in biosecurity interceptions. Here, a novel approach is taken to evaluate the potential for provenance resolution of insect samples through multiple biogeochemical markers. The international pest, Helicoverpa armigera, has been used as a model species to assess the validity of using naturally occurring δ2H, 87Sr/86Sr, 207Pb/206Pb and 208Pb/206Pb isotope ratios and trace element concentration signatures from single moth specimens for regional assignment to natal origin. None of the biogeochemical markers selected were individually able to separate moths from the different experimental regions (150–3000 km apart). Conversely, using multivariate analysis, the region of origin was correctly identified for approximately 75% of individual H. armigera samples. The geographic resolution

  13. Lead isotopes and trace metals in dust at Yucca Mountain

    USGS Publications Warehouse

    Kwak, Loretta; Neymark, Leonid A.; Peterman, Zell E.

    2008-01-01

    Lead (Pb)-isotope compositions and trace-metal concentrations were determined for samples of dust collected from underground and surface locations at and near the proposed radioactive waste repository at Yucca Mountain, Nevada. Rare earth element concentrations in the dust samples from the underground tunnels are similar to those in wholerock samples of the repository host rocks (Miocene Tiva Canyon Tuff and Topopah Spring Tuff), supporting interpretation that the subsurface dust is mainly composed of rock comminuted during tunnel construction. Other trace metals (arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, lead, antimony, thallium, and zinc) are variably enriched in the subsurface dust samples relative to the average concentrations in the host rocks. Average concentrations of arsenic and lead in dust samples, high concentrations of which can cause corrosion of waste canisters, have enrichment factors from 1.2 to 1.6 and are insignificant relative to the range of concentrations for these metals observed in the host rock samples. Most dust samples from surface sites also are enriched in many of these trace metals relative to average repository host rocks. At least some of these enrichments may be artifacts of sampling. Plotted on a 208Pb/206Pb-207Pb/206Pb graph, Pb-isotope compositions of dust samples from underground sites form a mixing line extending from host-rock Pb-isotope compositions towards compositions of many of the dust samples from surface sites; however, combined Pb concentration and isotope data indicate the presence of a Pbenriched component in the subsurface dust that is not derived from host rock or surface dust and may derive from anthropogenic materials introduced into the underground environment.

  14. Childhood lead exposure in an industrial town in China: coupling stable isotope ratios with bioaccessible lead.

    PubMed

    Li, Hong-Bo; Chen, Kai; Juhasz, Albert L; Huang, Lei; Ma, Lena Q

    2015-04-21

    Fingerprinting based on stable isotopes of lead (Pb) in blood and environmental media helps to identify Pb exposure pathways in children. However, previous studies used stable isotopes of total Pb in media. In this study, a wire rope production town in China (Zhuhang) was selected for investigating the effectiveness of using isotope ratios in bioaccessible Pb to identify childhood Pb exposure pathways. Blood Pb levels of 115 children in Zhuhang were 1.7-20.4 μg dL(-1), averaging 6.1 ± 3.2 μg dL(-1) (mean ± standard deviation), and were ∼1.6 times the national average in China (3.9 ± 1.8 μg dL(-1)). Among different environmental media (housedust, soil, PM10, vegetables, rice, and drinking water), housedust (695 ± 495 mg kg(-1)) and vegetables [0.36 ± 0.40 mg (kg of fresh weight)(-1)] contained elevated Pb concentrations. The isotope ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb) of total Pb were the highest in housedust (0.8587 ± 0.0039 and 2.1049 ± 0.0087) but lower than blood Pb ratios (0.8634 ± 0.0027 and 2.1244 ± 0.0061). When using bioaccessible Pb in housedust (0.8639 ± 0.0018 and 2.1171 ± 0.0036), the isotope ratios overlapped with blood Pb ratios, suggesting that incidental ingestion of housedust was the predominant contributor to children's blood Pb. Coupling the stable isotope technique with bioaccessible Pb is more reliable for identifying Pb exposure pathways than total Pb determinations. PMID:25803404

  15. The recycling of marine carbonates and sources of HIMU and FOZO ocean island basalts

    NASA Astrophysics Data System (ADS)

    Castillo, Paterno R.

    2015-02-01

    Many, and perhaps all, oceanic island basalts (OIB) clearly contain a component of crustal materials that have been returned to the mantle through subduction or other processes. One of the first recycled materials to be identified as a potential source of OIB was mid-ocean ridge basalt (MORB), and this was later fine-tuned as having a long time-integrated (b.y.) high U/Pb ratio or high μ (HIMU) and producing OIB with the most radiogenic Pb isotopic ratios (206Pb/204Pb > 20). However, it is becoming more evident that the compositional connection between subducted MORB and HIMU basalts is problematic. As an alternative hypothesis, a small amount (a few %) of recycled Archaean marine carbonates (primarily CaCO3) is proposed to be the main source of the distinct 206Pb/204Pb, 207Pb/204Pb and 87Sr/86Sr isotopic and major-trace element compositions of classic HIMU and post-Archaean marine carbonates for younger HIMU or the so-called FOZO mantle source. As an extension of the hypothesis, a conceptual model that combines the separate evolutionary histories of ancient oceanic lithosphere, which is the source of OIB, and upper mantle, which is the source of MORB, is also proposed. The model claims that FOZO mainly consists of the lithospheric mantle portion of the ancient metamorphosed oceanic slabs that have accumulated in the deep mantle. Such an ultramafic source is geochemically depleted due to prior extraction of basaltic melt plus removal of the enriched subduction component from the slab through dehydration and metamorphic processes. Combined with other proposed models in the literature, the conceptual model can provide reasonable solutions for the 208Pb/204Pb, 143Nd/144Nd, 176Hf/177Hf, and 3He/4He isotopic paradoxes or complexities of oceanic lavas. Although these simultaneous solutions for individual paradoxes are qualitative and non-unique, these are unified under a single, marine carbonate recycling hypothesis.

  16. Some Pb and Sr isotopic measurements on eclogites from the Roberts Victor mine, South Africa

    USGS Publications Warehouse

    Manton, W.I.; Tatsumoto, M.

    1971-01-01

    Five nodules of eclogite, one nodule of garnet peridotite and one sample of kimberlite from the Roberts Victor mine were analyzed for concentrations of U, Th, Pb, Rb and Sr and isotopic compositions of Pb and Sr. In the eclogites, U content ranges from 0.09 to 0.26 ppm, Th from 0.35 to 1.1 ppm, Pb from 0.79 to 5.5 ppm, Rb from 2.1 to 28 ppm and Sr from 133 to 346 ppm; 206Pb/204Pb ratios range from 14.8 to 18.5, 207Pb/204Pb from 14.9 to 15.7, 208Pb/204Pb from 35.2 to 38.5. The garnet peridotite contains 0.22 ppm U, 0.97 ppm Th, 1.05 ppm Pb, 6.9 ppm Rb and 108 ppm Sr and the kimberlite contains 2.5 ppm U, 30 ppm Th, 37 ppm Pb, 113 ppm Rb and 2040 ppm Sr. The lead in the eclogites has two components, a lead pyroextractable at 1100-1200?? and a non-pyroextractable residual lead. In three of the eclogites, which are to some extent altered, a proportion of the pyroextractable lead may be contaminating lead from the kimberlite, but an altered kyanite eclogite does not appear to be contaminated by this same kimberlite. The pyroextractable lead from a less altered eclogite contains a much larger proportion of 206Pb. Compositions calculated for the residual leads vary greatly. In many of the pyroextraction runs the primary eclogitic phases disappeared and the new phases plagioclase, clinopyroxene and a magnetic iron compound were formed. Why part of the lead should have been retained by these new phases is not understood. ?? 1971.

  17. Character of the pre-Mesozoic basement along the edge of the western US craton: Pb isotopic evidence from Mesozoic plutonism

    SciTech Connect

    Wooden, J.L.; Kistler, R.W.; Robinson, A.; Tosdal, R.M. ); Wright, J.E. . Dept. of Geology and Geophysics)

    1993-04-01

    The pre-Mesozoic cratonic crust of the western US was a composite of provinces composed mostly of Archean and Early Proterozoic rocks that had been truncated by Late Proterozoic rifting and had some new Paleozoic crust added along the western edge. Mesozoic and younger geologic events greatly obscured this pre-Mesozoic basement along the craton edge. However, the Pb isotopic signatures of Mesozoic plutons provide significant clues to the character of the crust in which they formed or were emplaced because of a strong contrast in Pb concentration between low-Pb, mantle-derived melts and Pb-rich crust. Thus, magmas whether derived from the crust or the mantle with subsequent crustal interaction, will likely have Pb isotopic compositions that reflect those of the crust. In the western US the Pb isotopic compositions of Mesozoic plutonic rocks have strong regional characteristics. Within the Early Proterozoic Mojave crustal province, Mesozoic plutonic rocks have a large range of 206Pb/204Pb ratios that plot above the crustal average, relatively high 207Pb/204Pb ratios that suggest an Archean contribution, and Pb and Sr isotopic compositions that are not correlated and that do not distinguish age groups. At the southern and western edge of this province where some 1.1 Ga rocks are exposed, 208Pb/204Pb ratios lie along the average crust model curve. These data suggest that any individual pluton provides a composite Pb isotopic composition for a discrete vertical section of the crust. Pb isotopic compositions of plutons in the Sierra Nevada and Great Basin are very different from those described above with 206Pb/204Pb ratios starting at 18.6, well-correlated Pb isotopic trends starting below the crustal model but extending to values that require input from the very radiogenic Wyoming province Archean crust, and good correlations between Pb and (1) Sr isotopic compositions and (2) W-E geographic position.

  18. Tracing dust transport from Middle-East over Delhi in March 2012 using metal and lead isotope composition

    NASA Astrophysics Data System (ADS)

    Kumar, S.; Aggarwal, S. G.; Malherbe, J.; Barre, J. P. G.; Berail, S.; Gupta, P. K.; Donard, O. F. X.

    2016-05-01

    A severe dust-storm which was originated in Middle-East crossed over Delhi during March 20-22, 2012. We have collected these dust-storm (DS) aerosol samples, and analyzed them for selected metals (As, Cd, Cr, Cu, Fe, Ni, Pb, Sb, Se, Sn, Sr, V and Zn) together with after dust-storm (ADS) and winter (WS) samples. High aerosol mass loadings were observed in DS samples (1097-1965 μg/m3). On the contrary, metals derived prominently from the anthropogenic sources were found lower in concentration compared to that of ADS and WS aerosols. We observed significantly high concentrations of Ni and V (which are abundantly found in crude oils of Middle-East origin) in the DS samples than that of ADS and WS samples. Also enrichment factor (EF) of these metals with respect to Fe shows no significant enrichment (<10). Fe (and Sr) concentrations were also 3-5 fold higher in DS samples compared to ADS and WS. These results suggest that Ni and V can be used as tracers for dust aerosols transported from Middle-East region. Lead isotope signatures can tell about the variation in the sources of urban aerosols. Therefore Pb isotope analyses of these samples were performed using MC-ICP-MS. The isotope ratios, 208Pb/206Pb is determined to be (mean ± sd) 2.1315 ± 0.0018, 2.1370 ± 0.0022 and 2.1389 ± 0.0016, whereas 206Pb/207Pb is 1.1311 ± 0.0022, 1.1244 ± 0.0017 and 1.1233 ± 0.0016 in DS, ADS and WS aerosols, respectively. There is a clear distinction in Pb isotope composition between DS and urban (ADS and WS) aerosols. Further, these results suggest that in urban aerosols, Pb is less radiogenic in nature compared to that of in transported dust aerosols collected in New Delhi.

  19. Lead concentrations and isotopes in aerosols from Xiamen, China.

    PubMed

    Zhu, Laimin; Tang, Jianwu; Lee, Ben; Zhang, Yu; Zhang, Feifei

    2010-11-01

    To investigate the magnitude and origin of lead (Pb) pollution in the atmosphere of Xiamen, China, 40 aerosol samples were collected from the coast of Xiamen from January to December 2003. All these samples were measured for Pb isotopic compositions ((208)Pb/(206)Pb=2.10897 ± 0.00297, (207)Pb/(206)Pb=0.85767 ± 0.00159, n=40) using a Multi-collector-Inductively Coupled Plasma Mass Spectrometer (MC-ICPMS). Thirty-five out of forty samples were also measured for Pb concentrations (79.1 ± 38.3 ng/m(3), n=35) by Atomic Absorption Spectroscopy (AAS). The results indicate that the Pb concentrations display significant seasonal variations while Pb isotopic ratios remain relatively constant. The Pb concentrations were high in January and February, abruptly decreased in March, remained relatively constant (but low) from April to August, and then gradually increased from September to December. This corresponds to the rainless climate in winter and rain scavenging in summer. The higher Pb concentration of Xiamen aerosols in winter and spring may be also caused by long-range transferred anthropogenic Pb during the northeastern monsoon seasons. Although the use of leaded gasoline in Xiamen was banned in 2000, our new data indicate that the Pb annual concentrations of aerosols in Xiamen increased about 12% when compared to the data measured between 1991 and 1993. Thus, Pb pollution in the atmosphere of Xiamen has not receded even after the phase-out of leaded gasoline. Our results further confirm the previous studies' conclusion that the primary source of atmospheric Pb in China, especially in South China, is the vast combustion of lead-containing coal, not leaded gasoline.

  20. Accumulation of atmospheric radionuclides and heavy metals in cryoconite holes on an Arctic glacier.

    PubMed

    Łokas, Edyta; Zaborska, Agata; Kolicka, Małgorzata; Różycki, Michał; Zawierucha, Krzysztof

    2016-10-01

    Surface of glaciers is covered by mineral and organic dust, together with microorganisms forming cryoconite granules. Despite fact that glaciers and ice sheets constitute significance part of land surface, reservoir of freshwater, and sites of high biological production, the knowledge on the cryoconite granules still remain unsatisfactory. This study presents information on radionuclide and heavy metal contents in cryoconites. Cryoconites collected from the Hans Glacier in SW Spitsbergen reveal high activity concentrations of anthropogenic ((238,239,240)Pu, (137)Cs, (90)Sr) and natural ((210)Pb) radionuclides. The (238)Pu/(239+240)Pu activity ratios in these cryoconites significantly exceed the mean global fallout ratio (0.025). The (238)Pu/(239+240)Pu ranged from 0.064 to 0.118. The (239+240)Pu/(137)Cs varied from 0.011 ± 0.003 to 0.030 ± 0.007. Such activity ratios as observed in these cryoconites were significantly higher than the values characterizing global fallout, pointing to possible contributions of these radionuclides from other sources. Heavy metals (Pb, Cd, Cu, Zn, Fe, and Mn) in cryoconites exceed both UCC concentrations and local rocks' concentrations, particularly for cadmium. The concentration ratios of stable lead isotopes ((206)Pb/(207)Pb, (208)Pb/(206)Pb) were determined to discriminate between the natural and anthropogenic sources of Pb in cryoconites and to confirm the strong anthropogenic contribution to heavy metal deposition in the Arctic. In investigated cryoconite holes, two groups of invertebrates, both extremophiles, Tardigrada and Rotifera were detected. Our study indicate that cryoconites are aggregates of mineral and organic substances on surfaces of glaciers are able to accumulate large amounts of airborne pollutants bound to extracellular polymeric substances secreted by microorganisms. PMID:27372266

  1. Impact of urbanization on sediment chemistry in small-scale watersheds, southeast Virginia.

    NASA Astrophysics Data System (ADS)

    Evans, M. J.; Packard, H.

    2007-12-01

    The state of Virginia contains only two natural bodies of water with the rest being comprised of mill ponds, farm ponds and impoundment lakes. These man made water bodies are ubiquitous along the eastern seaboard. Southeast Virginia (Williamsburg, Jamestown and surrounding counties) was the locus of early European settlement and many of the local ponds date back to the early colonial period. As such, the sediment record in these ponds provides a unique historical record of the impact human activity can have on small watersheds. Two small man-made ponds (Lake Matoaka and Jolly Pond) were studied. Both ponds lie within the James River basin, a major feeder to the Chesapeake Bay. Both drainage basins cover ~600 ha but differ significantly in the level of development. Lake Matoaka was originally dammed ca. 1720. The Matoaka drainage is currently experiencing rapid development (~22% high population residential/commercial) and includes the College of William & Mary's campus. Jolly Pond and the two dams that created it first appear on maps dating back to 1863. The Jolly Pond basin is largely dominated by forests and agricultural land. Sediment cores were taken from both ponds using a Russian peat corer, Matoaka to 1.5m depth and Jolly Pond to 0.9m dpeth. Sediment splits were analyzed for total exchangeable lead concentration and lead isotopes (207Pb/206Pb & 208Pb/206Pb), as well total carbon and nitrogen. Carbon/Nitrogen ratios were used to indicate changes in water level and dam height increases. Lead concentrations in both cores show a peak associated with leaded gasoline use. [Pb] in Matoaka are significant (~320 ppm) and show a clear anthropogenic isotopic signature. Jolly Pond [Pb] are surprisingly low and are close to background values. These data indicate that even minimal development has significant impact on sediment chemistry. Likely lead sources for Lake Matoaka include road and building runoff and lead aerosols.

  2. Investigation of Lead Target Nuclei Used on Accelerator-Driven Systems for Tritium Production

    NASA Astrophysics Data System (ADS)

    Tel, E.; Aydin, A.

    2012-02-01

    High-current proton accelerators are being researched at Los Alamos National Laboratory and other laboratories for accelerator production of tritium, transmuting long-lived radioactive waste into shorter-lived products, converting excess plutonium, and producing energy. These technologies make use of spallation neutrons produced in ( p,xn) and ( n,xn) nuclear reactions on high-Z targets. Through ( p,xn) and ( n,xn) nuclear reactions, neutrons are produced and are moderated by heavy water. These moderated neutrons are subsequently captured on 3He to produce tritium via the ( n,p) reaction. Tritium self-sufficiency must be maintained for a commercial fusion power plant. Rubbia succeeded in a proposal of a full scale demonstration plant of the Energy Amplifier. This plant is to be known the accelerator-driven system (ADS). The ADS can be used for production of neutrons in spallation neutron source and they can act as an intense neutron source in accelerator-driven subcritical reactors, capable of incinerating nuclear waste and of producing energy. Thorium and Uranium are nuclear fuels and Lead, Bismuth, Tungsten are the target nuclei in these reactor systems. The spallation targets can be Pb, Bi, W, etc. isotopes and these target material can be liquid or solid. Naturally Lead includes the 204Pb (%1.42), 206Pb (%24.1), 207Pb (%22.1) and 208Pb (%52.3) isotopes. The design of ADS systems and also a fusion-fission hybrid reactor systems require the knowledge of a wide range of better data. In this study, by using Hartree-Fock method with an effective nucleon-nucleon Skyrme interactions rms nuclear charge radii, rms nuclear mass radii, rms nuclear proton, neutron radii and neutron skin thickness were calculated for the 204, 206, 208Pb isotopes . The calculated results have been compared with those of the compiled experimental and theoretical values of other studies.

  3. Chemical and isotopic studies of granitic Archean rocks, Owl Creek Mountains, Wyoming: Uranium-thorium-lead systematics of an Archean granite from the Owl Creek Mountains, Wyoming

    SciTech Connect

    Stuckless, J.S.; Nkomo, I.T.; Butt, K.A.

    1986-01-01

    Isotopic analyses of apparently unaltered whole-rock samples of a granite from the Owl Creek Mountains, Wyo., yield a lead-lead isochron age of 2730 {plus minus} 35 Ma, which is somewhat older than the age obtained by the rubidium-strontium whole-rock method. Thorium-lead data for the same samples deviate markedly from an isochronal relation; however, calculated initial {sup 208}Pb/{sup 204}Pb ratios correlate with whole-rock {delta}{sup 18}O values and lead to the conclusion that the {sup 232}Th-{sup 208}Pb data are not colinear because of an originally heterogeneous granitic magma. Relationships in the {sup 207}Pb/{sup 235}U-{sup 206}Pb/{sup 238}U system show that uranium was mobilized during early Laramide time or shortly before, such that most surface and shallow drill-core samples lost 60-80 percent of their uranium, and some fractured, deeper drill-core samples gained from 50 to 10,000 percent uranium. Fission-track maps show that much uranium is located along edges and cleavages of biotite and magnetic where it is readily accessible to oxidizing ground water. Furthermore, qualitative comparisons of uranium distribution in samples with excess radiogenic lead and in samples with approximately equilibrium amounts of uranium and lead suggest that the latter contain more uranium in these readily accessible sites. Unlike other granites that have uranium distributions and isotopic systematics similar to those observed in this study, the granite of the Owl Creek Mountains is not associated with economic uranium deposits.

  4. Lead in the Getchell-Turquoise ridge Carlin-type gold deposits from the perspective of potential igneous and sedimentary rock sources in Northern Nevada: Implications for fluid and metal sources

    USGS Publications Warehouse

    Tosdal, R.M.; Cline, J.S.; Fanning, C.M.; Wooden, J.L.

    2003-01-01

    Lead isotope compositions of bulk mineral samples (fluorite, orpiment, and realgar) determined using conventional techniques and of ore-stage arsenian pyrite using the Sensitive High Resolution Ion-Microprobe (SHRIMP) in the Getchell and Turquoise Ridge Carlin-type gold deposits (Osgood Mountains) require contribution from two different Pb sources. One Pb source dominates the ore stage. It has a limited Pb isotope range characterized by 208Pb/206Pb values of 2.000 to 2.005 and 207Pb/206Pb values of 0.8031 to 0.8075, as recorded by 10-??m-diameter spot SHRIMP analyses of ore-stage arsenian pyrite. These values approximately correspond to 206Pb/204Pb of 19.3 to 19.6, 207Pb/204Pb of 15.65 to 15.75, and 208Pb/204Pb of 39.2 to 39.5. This Pb source is isotopically similar to that in average Neoproterozoic and Cambrian elastic rocks but not to any potential magmatic sources. Whether those clastic rocks provided Pb to the ore fluid cannot be unequivocally proven because their Pb isotope compositions over the same range as in ore-stage arsenian pyrite are similar to those of Ordovician to Devonian siliciclastic and calcareous rocks. The Pb source in the calcareous rocks most likely is largely detrital minerals, since that detritus was derived from the same sources as the detritus in the Neoproterozoic and Cambrian clastic rocks. The second Pb source is characterized by a large range of 206Pb/204Pb values (18-34) with a limited range of 208Pb/204Pb values (38.1-39.5), indicating low but variable Th/U and high and variable U/Pb values. The second Pb source dominates late and postore-stage minerals but is also found in preore sulfide minerals. These Pb isotope characteristics typify Ordovician to Devonian siliciclastic and calcareous rocks around the Carlin trend in northeast Nevada. Petrologically similar rocks host the Getchell and Turquoise Ridge deposits. Lead from the second source was either contributed from the host sedimentary rock sequences or brought into the

  5. Stable lead isotopic analyses of historic and contemporary lead contamination of San Francisco Bay estuary

    USGS Publications Warehouse

    Ritson, P.I.; Bouse, R.M.; Flegal, A.R.; Luoma, S.N.

    1999-01-01

    Variations in stable lead isotopic composition (240Pb, 206Pb, 207Pb, 208Pb) in three sediment cores from the San Francisco Bay estuary document temporal changes in sources of lead during the past two centuries. Sediment, with lead from natural geologic sources, and relatively homogeneous lead isotopic compositions are overlain by sediments whose isotopic compositions indicate change in the sources of lead associated with anthropogenic modification of the estuary. The first perturbations of lead isotopic composition in the cores occur in the late 1800s concordant with the beginning of industrialization around the estuary. Large isotopic shifts, toward lower 206Pb/207Pb, occur after the turn of the century in both Richardson and San Pablo Bays. A similar relationship among lead isotopic compositions and lead concentrations in both Bays suggest contamination from the same source (a lead smelter). The uppermost sediments (post 1980) of all cores also have a relatively homogenous lead isotopic composition distinct from pre-anthropogenic and recent aerosol signatures. Lead isotopic compositions of leachates from fourteen surface sediments and five marsh samples from the estuary were also analyzed. These analyses suggest that the lead isotopic signature identified in the upper horizons of the cores is spatially homogeneous among recently deposited sediments throughout the estuary. Current aerosol lead isotopic compositions [Smith, D.R., Niemeyer, S., Flegal, A.R., 1992. Lead sources to California sea otters: industrial inputs circumvent natural lead biodepletion mechanisms. Environmental Research 57, 163-175] are distinct from the isotopic compositions of the surface sediments, suggesting that the major source of lead is cycling of historically contaminated sediments back through the water column. Both the upper core sediments and surface sediments apparently derive their lead predominantly from sources internal to the estuary. These results support the idea that

  6. Lead isotopic compositions of common arsenical pesticides used in New England

    USGS Publications Warehouse

    Ayuso, Robert; Foley, Nora; Robinson, Gilpin; Wandless, Gregory; Dillingham, Jeremy

    2004-01-01

    . The new data characterize these anthropogenic sources. The data show that the arsenical pesticides have similar compositions: 208Pb/207Pb = 2.3839-2.4721, 206Pb/207Pb = 1.1035-1.2010, and 206Pb/204Pb = 17.070-18.759 and, more importantly, that the pesticides overlap the composition of the stream sediments that represent the areas with the most extensive agricultural use. Copper acetoarsenite (Paris green), arsenic oxide, methyl arsonic acid, methane arsonic acid, and arsanilic acid were also analyzed and have lead isotope compositions that range widely. An important source of arsenic and metals to most of the stream sediment samples in New England appears to be weathering products from rocks and industrial lead, but the extensive use of arsenical pesticides and herbicides up to about the 1960s can also be a significant anthropogenic source in agricultural regions.

  7. Pb, Nd, and Sr isotopic evidence for a multicomponent source for rocks of Cook-Austral Islands and heterogeneities of mantle plumes

    SciTech Connect

    Nakamura, Yoichi; Tatsumoto, Mitsunobu )

    1988-12-01

    Sr, Nd, and Pb isotopic compositions were measured in alkane volcanic rocks from the South Cook Islands and the Austral Islands. The results show that the Cook-Austral rocks have an extremely wide range in isotopic compositions of Pb: {sup 206}Pb/{sup 204}Pb from 18.25 to 21.76, {sup 207}Pb/{sup 204}Pb from 15.48 to 15.83, and {sup 208}Pb/{sup 204}Pb from 38.37 to 40.62, whereas isotopic compositions of Sr and Nd are less variable. Isotopically, Mangaia, Rimatara, and Rurutu form one group, which shows extremely ratiogenic Pb isotopic compositions but near-MORB (mid-ocean ridge basalts) values for Sr and Nd isotopic ratios. In contrast, samples from Aitutaki, Rarotonga, Mauke, and Atiu (Aitutaki group) have high {sup 207}Pb/{sup 204}Pb and {sup 208}Pb/{sup 204}Pb and moderately high {sup 87}Sr/{sup 86}Sr (Dupal anomaly). The Aitutaki group could have been derived from heterogeneous mantle plumes, which rose from the enriched deep mantle (the almost primitive lower mantle or recycled continental and oceanic slabs). On the other hand, the Mangaia component could have been derived from the depleted upper mantle which may have been metasomatized with a Co{sub 2}-rich fluid, as indicated by the near-MORB values of Sr and Nd isotopes. Although Pb isotopic data of the two groups cannot be distinguished from each other statistically, the end components of the Pb-Pb system do not match with those of the Nd-Sr system. Thus, the data must be explained by a multi-, at least three, component mixing model: the mantle plumes, metasomatized upper mantle, and lithosphere. The K-Ar ages and isotopic characteristics of the Cook-Austral rocks indicate that if one mantle plume rises from the deep mantle in this region, it has separated into at least two segments on the way to the surface.

  8. Pb, Nd, and Sr isotopic evidence for a multicomponent source for rocks of Cook-Austral Islands and heterogeneities of mantle plumes

    USGS Publications Warehouse

    Nakamura, Y.; Tatsumoto, M.

    1988-01-01

    Sr, Nd, and Pb isotopic compositions were measured in alkaline volcanic rocks (alkali basalt, ankaramite, nephelinite, phonolite, and trachyte) from the South Cook Islands (Aitutaki, Mauke, Rarotonga, Atiu, and Mangaia) and the Austral Islands (Rimatara and Rurutu). The results show that the Cook-Austral rocks have an extremely wide range in isotopic compositions of Pb: 206Pb 204Pb from 18.25 to 21.76, 207pb 204pb from 15.48 to 15.83, and sol208pb 204Pb from 38.37 to 40.62, whereas isotopic compositions of Sr and Nd are less variable. Isotopically, Mangaia, Rimatara, and Rurutu form one group (Mangaia group), which shows extremely radiogenic Pb isotopic compositions but near-MORB (mid-oceanic ridge basalts) values for Sr and Nd isotopic ratios. In contrast, samples from Aitutaki, Rarotonga, Mauke, and Atiu (Aitutaki group) have high 207Pb 204Pb and 208Pb 204Pb and moderately high 87Sr 86Sr (Dupal anomaly). The Aitutaki group could have been derived from heterogeneous mantle plumes, which rose from the enriched deep mantle (the almost primitive lower mantle or recycled continental and oceanic slabs). On the other hand, the Mangaia component could have been derived from the depleted upper mantle which may have been metasomatized with a CO2-rich fluid, as indicated by the near-MORB values of Sr and Nd isotopes. Although Pb isotopic data of the two groups cannot be distinguished from each other statistically, the end components of the Pb-Pb system do not match with those of the Nd-Sr system. Thus, the data must be explained by a multi-, at least three, component mixing model: the mantle plumes (Dupal component and a recycled oceanic slab), metasomatized upper mantle, and lithosphere. The K-Ar ages and isotopic characteristics of the Cook-Austral rocks indicate that if one mantle plume rises from the deep mantle in this region, it has separated into at least two segments on the way to the surface. ?? 1988.

  9. Bioavailability and Sources of Lead in the Terrestrial Environment of Egypt

    NASA Astrophysics Data System (ADS)

    Marzouk, Ezzat; Shetaya, Waleed; Elkassas, Mohamed; Mohamed, Elham; Bailey, Elizabeth; Young, Scott

    2016-04-01

    . Isotopic ratios (206Pb/207Pb and 208Pb/207Pb) fell on a mixing line between end-members attributed to petrol and regional geogenic Pb sources and clearly showed a distinction between Pb from geogenic and anthropogenic sources (mainly petrol-derived Pb). In contaminated locations, there was clear evidence that petrol-derived Pb, in average, remained considerably more labile than Pb from the soil parent material. However, in all samples, both petrol-derived and geogenic Pb contributed to the labile fraction depending on soil conditions.

  10. Oceanic Pb-isotopic sources of proterozoic and paleozoic volcanogenic massive sulfide deposits on Prince of Wales Island and vicinity, southeastern Alaska

    USGS Publications Warehouse

    Ayuso, Robert A.; Karl, Susan M.; Slack, John F.; Haeussler, Peter J.; Bittenbender, Peter E.; Wandless, Gregory A.; Colvin, Anna

    2005-01-01

    Volcanogenic massive sulfide (VMS) deposits on Prince of Wales Island and vicinity in southeastern Alaska are associated with Late Proterozoic through Cambrian volcanosedimentary rocks of the Wales Group and with Ordovician through Early Silurian felsic volcanic rocks of the Moira Sound unit (new informal name). The massive sulfide deposits in the Wales Group include the Big Harbor, Copper City, Corbin, Keete Inlet, Khayyam, Ruby Tuesday, and Stumble-On deposits, and those in the Moira Sound unit include the Barrier Islands, Moira Copper, Niblack, and Nichols Bay deposits. Pb-isotopic signatures were determined on sulfide minerals (galena, pyrite, chalcopyrite, pyrrhotite, and sphalerite) to constrain metal sources of the massive sulfides and for comparison with data for other deposits in the region. Except for the Ruby Tuesday deposit, galena is relatively rare in most of these deposits. Pb-isotopic signatures distinguish the mainly Cu+Zn±Ag±Au massive sulfide deposits in the Wales Group from the Zn+Cu±Ag±Au massive sulfide deposits in the Moira Sound unit. Among the older group of deposits, the Khayyam deposit has the widest variation in Pb-isotopic ratios (206Pb/204Pb=17.169–18.021, 207Pb/204Pb=15.341–15.499, 208Pb/204Pb=36.546–37.817); data for the other massive sulfide deposits in the Wales Group overlap the isotopic variations in the Khayyam deposit. Pb-isotopic ratios for both groups of deposits are lower than those on the average crustal Pbevolution curve (µ=9.74), attesting to a large mantle influence in the Pb source. All the deposits show no evidence for Pb evolution primarily in the upper or lower continental crust. Samples from the younger group of deposits have scattered Pb-isotopic compositions and plot as a broad band on uranogenic and thorogenic Pb diagrams. Data for these deposits overlap the trend for massive sulfide deposits in the Wales Group but extend to significantly more radiogenic Pb-isotopic values. Pb-isotopic ratios of

  11. Lead contamination of the Seine River, France: geochemical implications of a historical perspective.

    PubMed

    Ayrault, Sophie; Roy-Barman, Matthieu; Le Cloarec, Marie-Françoise; Priadi, Cindy Rianti; Bonté, Philippe; Göpel, Christa

    2012-05-01

    Four sediment cores collected in the Seine River basin and dated between 1916 and 2003 were analyzed for lead concentrations and isotopic composition. In all four cores, the measured Pb concentration (up to 460 mg kg(-1)) lies significantly above the natural background (27-40 mg kg(-1)), although a significant decrease (down to 75 mg kg(-1)) was observed during the second half of the 20th century which can be explained by the reduction of lead emissions. The (206)Pb/(207)Pb ratio measured in these samples indicates that the main source of Pb used in the Paris conurbation is characterized by a "Rio Tinto" signature (defined as (206)Pb/(207)Pb=1.1634 ± 0.0001). A high contribution, up to 25%, from the leaded gasoline (characterized by (206)Pb/(207)Pb=1.08 ± 0.02) is revealed in the Seine River downstream Paris, indicating that lead from the leaded gasoline is preferentially released to the river. The dominating Pb signature in the Paris conurbation that is currently sampled through incinerators fumes ((206)Pb/(207)Pb=1.1550 ± 0.0005) and waste water treatment plant ((206)Pb/(207)Pb=1.154 ± 0.002), represents a mixture of highly recycled lead from the Rio Tinto mine and lead from leaded gasoline (imprinted by the low (206)Pb/(207)Pb of the Broken Hill mine). This signature is called "urban" rather than "industrial", because it is clearly distinct from the Pb that is found in areas contaminated by heavy industry, i.e. the heavy industries located on the Oise River which used lead from European ores characterized by high (206)Pb/(207)Pb ratios (~1.18-1.19) and possibly a minor amount of North American lead ((206)Pb/(207)Pb ratios>1.20). The "urban" signature is also found in a rural area upstream of Paris in the 1970's. At the Seine River mouth in 2003, Pb with an urban signature represents 70% of the total Pb sediment content, with the 30% remaining corresponding to natural Pb.

  12. Structure of ²⁰⁷Pb populated in ²⁰⁸Pb + ²⁰⁸Pb deep-inelastic collisions*

    DOE PAGES

    Shand, C. M.; Wilson, E.; Podolyák, Zs.; Grawe, H.; Brown, B. A.; Fornal, B.; Janssens, R. V. F.; Bowry, M.; Bunce, M.; Carpenter, M. P.; et al

    2015-01-01

    The yrast structure of 207Pb above the 13/2+ isomeric state has been investigated in deep-inelastic collisions of 208Pb and 208Pb at ATLAS, Argonne National Laboratory. New and previously observed transitions were measured using the Gammasphere detector array. The level scheme of 207Pb is presented up to ~ 6 MeV, built using coincidence and γ-ray intensity analyses. In addition, the spin and parity assignments of states were made, based on angular distributions and comparisons to shell model calculations.

  13. Surface dust wipes are the best predictors of blood leads in young children with elevated blood lead levels

    SciTech Connect

    Gulson, Brian; Anderson, Phil; Taylor, Alan

    2013-10-15

    Background: As part of the only national survey of lead in Australian children, which was undertaken in 1996, lead isotopic and lead concentration measurements were obtained from children from 24 dwellings whose blood lead levels were ≥15 µg/dL in an attempt to determine the source(s) of their elevated blood lead. Comparisons were made with data for six children with lower blood lead levels (<10 µg/dL). Methods: Thermal ionisation and isotope dilution mass spectrometry were used to determine high precision lead isotopic ratios ({sup 208}Pb/{sup 206}Pb, {sup 207}Pb/{sup 206}Pb and {sup 206}Pb/{sup 204}Pb) and lead concentrations in blood, dust from floor wipes, soil, drinking water and paint (where available). Evaluation of associations between blood and the environmental samples was based on the analysis of individual cases, and Pearson correlations and multiple regression analyses based on the whole dataset. Results and discussion: The correlations showed an association for isotopic ratios in blood and wipes (r=0.52, 95% CI 0.19–0.74), blood and soil (r=0.33, 95% CI −0.05–0.62), and blood and paint (r=0.56, 95% CI 0.09–0.83). The regression analyses indicated that the only statistically significant relationship for blood isotopic ratios was with dust wipes (B=0.65, 95% CI 0.35–0.95); there were no significant associations for lead concentrations in blood and environmental samples. There is a strong isotopic correlation of soils and house dust (r=0.53, 95% CI 0.20–0.75) indicative of a common source(s) for lead in soil and house dust. In contrast, as with the regression analyses, no such association is present for bulk lead concentrations (r=−0.003, 95% CI −0.37–0.36), the most common approach employed in source investigations. In evaluation of the isotopic results on a case by case basis, the strongest associations were for dust wipes and blood. -- Highlights: • Children with elevated blood lead ≥15 µg/dL compared with a group with <10

  14. Uranium-lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

    SciTech Connect

    Gaffney, A M; Borg, L E; Connelly, J N

    2006-12-22

    Uranium-lead ratios (commonly represented as {sup 238}U/{sup 204}Pb = {mu}) calculated for the sources of martian basalts preserve a record of petrogenetic processes that operated during early planetary differentiation and formation of martian geochemical reservoirs. To better define the range of {mu} values represented by the source regions of martian basalts, we completed U-Pb elemental and isotopic analyses on whole rock, mineral and leachate fractions from the martian meteorite Queen Alexandra Range 94201 (QUE 94201). The whole rock and silicate mineral fractions have unradiogenic Pb isotopic compositions that define a narrow range ({sup 206}Pb/{sup 204}Pb = 11.16-11.61). In contrast, the Pb isotopic compositions of weak HCl leachates are more variable and radiogenic. The intersection of the QUE 94201 data array with terrestrial Pb in {sup 206}Pb/{sup 204}Pb-{sup 207}Pb/{sup 204}Pb-{sup 208}Pb/{sup 204}Pb compositional space is consistent with varying amounts of terrestrial contamination in these fractions. We calculate that only 1-7% contamination is present in the purified silicate mineral and whole rock fractions, whereas the HCl leachates contain up to 86% terrestrial contamination. Despite the contamination, we are able to use the U-Pb data to determine the initial {sup 206}Pb/{sup 204}Pb of QUE 94201 (11.086 {+-} 0.008) and calculate the {mu} value of the QUE 94201 mantle source to be 1.823 {+-} 0.008. This is the lowest {mu} value calculated for any martian basalt source, and, when compared to the highest values determined for martian basalt sources, indicates that {mu} values in martian source reservoirs vary by at least 100%. The range of source {mu} values further indicates that the {mu} value of bulk silicate Mars is approximately three. The amount of variation in the {mu} values of the mantle sources ({mu} {approx} 2-4) is greater than can be explained by igneous processes involving silicate phases alone. We suggest the possibility that a small

  15. Lead isotopes combined with a sequential extraction procedure for source apportionment in the dry deposition of Asian dust and non-Asian dust.

    PubMed

    Lee, Pyeong-Koo; Yu, Soonyoung

    2016-03-01

    Lead isotopic compositions were determined in leachates that were generated using sequential extractions of dry deposition samples of Asian dust (AD) and non-Asian dust (NAD) and Chinese desert soils, and used to apportion Pb sources. Results showed significant differences in (206)Pb/(207)Pb and (206)Pb/(204)Pb isotopic compositions in non-residual fractions between the dry deposition samples and the Chinese desert soils while (206)Pb/(207)Pb and (206)Pb/(204)Pb isotopic compositions in residual fraction of the dry deposition of AD and NAD were similar to the mean (206)Pb/(207)Pb and (206)Pb/(204)Pb in residual fraction of the Alashan Plateau soil. These results indicate that the geogenic materials of the dry deposition of AD and NAD were largely influenced by the Alashan Plateau soil, while the secondary sources of the dry deposition were different from those of the Chinese desert soils. In particular, the lead isotopic compositions in non-residual fractions of the dry deposition were homogenous, which implies that the non-residual four fractions (F1 to F4) shared the primary anthropogenic origin. (206)Pb/(207)Pb values and the predominant wind directions in the study area suggested that airborne particulates of heavily industrialized Chinese cities were one of the main Pb sources. Source apportionment calculations showed that the average proportion of anthropogenic Pb in the dry deposition of AD and NAD was 87% and 95% respectively in total Pb extraction, 92% and 97% in non-residual fractions, 15% and 49% in residual fraction. Approximately 81% and 80% of the anthropogenic Pb was contributed by coal combustion in China in the dry deposition of AD and NAD respectively while the remainder was derived from industrial Pb contamination. The research result proposes that sequential extractions with Pb isotope analysis are a useful tool for the discrimination of anthropogenic and geogenic origins in highly contaminated AD and NAD.

  16. Lead isotope ratios in bone ash of blesbok (Damaliscus pygargus phillipsi): a means of screening for the accumulation of contaminants from uraniferous rocks.

    PubMed

    Nöthling, Johan O; Du Toit, Johannes S; Myburgh, Jan G

    2014-09-19

    This study was done to determine whether blesbok (Damaliscus pygargus phillipsi) from the Krugersdorp Game Reserve (KGR) in Gauteng Province, South Africa have higher concentrations of (238)U and higher (206)Pb/(204)Pb and (207)Pb/(204)Pb ratios in their bone ash than blesbok from a nearby control reserve that is not exposed to mine water and has no outcrops of uraniferous rocks. Eight blesbok females from the KGR and seven from the control site, all killed with a brain shot, were used. A Thermo X-series 2 quadrupole ICPMS was used to measure the concentrations of (238)U and lead and a Nu Instruments NuPlasma HR MC-ICP-MS to measure the lead isotope ratios in the tibial ash from each animal. KGR blesbok had higher mean concentrations of (238)U (P = 0.02) and ratios of (206)Pb/(204)Pb and (207)Pb/(204)Pb (P < 0.00001) than the control blesbok. The probability of rejecting the false null hypothesis of no difference in the (206)Pb/(204)Pb or (207)Pb/(204)Pb ratios between KGR and control reserve animals (the power of the test) was 0.999. The blesbok from the KGR accumulated contaminants from an uraniferous environment. The (206)Pb/(204)Pb and (207)Pb/(204)Pb ratios in tibial ash proved effective in confirming accumulation of contaminants from uraniferous rocks.

  17. A century long sedimentary record of anthropogenic lead (Pb), Pb isotopes and other trace metals in Singapore.

    PubMed

    Chen, Mengli; Boyle, Edward A; Switzer, Adam D; Gouramanis, Chris

    2016-06-01

    Reconstructing the history of metal deposition in Singapore lake sediments contributes to understanding the anthropogenic and natural metal deposition in the data-sparse Southeast Asia. To this end, we present a sedimentary record of Pb, Pb isotopes and eleven other metals (Ag, As, Ba, Cd, Co, Cr, Cu, Ni, Tl, U and Zn) from a well-dated sediment core collected near the depocenter of MacRitchie Reservoir in central Singapore. Before the 1900s, the sedimentary Pb concentration was less than 2 mg/kg for both soil and sediment, with a corresponding (206)Pb/(207)Pb of ∼1.20. The Pb concentration increased to 55 mg/kg in the 1990s, and correspondingly the (206)Pb/(207)Pb decreased to less than 1.14. The (206)Pb/(207)Pb in the core top sediment is concordant with the (206)Pb/(207)Pb signal of aerosols in Singapore and other Southeast Asian cities, suggesting that Pb in the reservoir sediment was mainly from atmospheric deposition. Using the Pb concentration in the topmost layer of sediment, the estimated atmospheric Pb flux in Singapore today is ∼1.6 × 10(-2) g/m(2) yr. The concentrations of eleven other metals preserved in the sediment were also determined. A principal component analysis showed that most of the metals exhibit an increasing trend towards 1990s with a local concentration peak in the mid-20(th) century.

  18. A century long sedimentary record of anthropogenic lead (Pb), Pb isotopes and other trace metals in Singapore.

    PubMed

    Chen, Mengli; Boyle, Edward A; Switzer, Adam D; Gouramanis, Chris

    2016-06-01

    Reconstructing the history of metal deposition in Singapore lake sediments contributes to understanding the anthropogenic and natural metal deposition in the data-sparse Southeast Asia. To this end, we present a sedimentary record of Pb, Pb isotopes and eleven other metals (Ag, As, Ba, Cd, Co, Cr, Cu, Ni, Tl, U and Zn) from a well-dated sediment core collected near the depocenter of MacRitchie Reservoir in central Singapore. Before the 1900s, the sedimentary Pb concentration was less than 2 mg/kg for both soil and sediment, with a corresponding (206)Pb/(207)Pb of ∼1.20. The Pb concentration increased to 55 mg/kg in the 1990s, and correspondingly the (206)Pb/(207)Pb decreased to less than 1.14. The (206)Pb/(207)Pb in the core top sediment is concordant with the (206)Pb/(207)Pb signal of aerosols in Singapore and other Southeast Asian cities, suggesting that Pb in the reservoir sediment was mainly from atmospheric deposition. Using the Pb concentration in the topmost layer of sediment, the estimated atmospheric Pb flux in Singapore today is ∼1.6 × 10(-2) g/m(2) yr. The concentrations of eleven other metals preserved in the sediment were also determined. A principal component analysis showed that most of the metals exhibit an increasing trend towards 1990s with a local concentration peak in the mid-20(th) century. PMID:26967352

  19. Isotopic tracing of landfill leachates and pollutant lead mobility in soil and groundwater.

    PubMed

    Vilomet, J D; Veron, A; Ambrosi, J P; Moustier, S; Bottero, J Y; Chatelet-Snidaro, L

    2003-10-15

    Here we provide evidence of the capability of stable lead isotopes to trace landfill leachate in a shallow groundwater. The municipal landfill we have investigated is located in southeastern France. It has no bottom liner, and wastes are placed directly on the ground. Stable lead isotopes allow the characterization of this landfill leachate signature (206Pb/207Pb = 1.189 +/- 0.004) that is clearly different from that of the local atmosphere (206Pb/207Pb = 1.150 +/- 0.006) and crustal lead (206Pb/207Pb = 1.200 +/- 0.005). Piezometers located in the direct vicinity of the landfill generally display this contaminant imprint. The landfill plume is monitored up to 1000 m downgradient of the landfill, in very good agreement with evaluation from chloride concentration. Meanwhile, 206Pb/207Pb ratios measured at a piezometer located 4600 m downgradient of the landfill suggest a contamination by the landfill plume. This result shows that the complexity of a pollutant plume dispersion in this shallow groundwater system requires several independent tracers to clearly resolve origin and transport pathways for contaminants. Furthermore, seasonal rainfall variation for this Mediterranean mixed Quaternary alluvion reservoir and the use of KCl fertilizers might favor an efficient remobilization of atmospheric lead in plowed soils and its transfer into groundwater as shown by lead isotope systematics.

  20. Pb contamination and isotopic composition of urban soils in Hong Kong.

    PubMed

    Wong, Coby Sze Chung; Li, Xiang Dong

    2004-02-01

    In the urban environment, intense human activities can lead to degradation of environmental quality and have potential long-term effects on human health. In the present study, Pb contamination of urban soil cores in Hong Kong was investigated using a combination of the 'total' concentration, chemical partitioning and isotopic composition of Pb in the soils. The analytical results showed that urban soil cores in close vicinity to high traffic volumes (> 40000 vehicles per day) were usually contaminated with Pb, suggesting atmospheric deposition of Pb as a consequence of vehicular emissions arising from the combustion of leaded gasoline in the past. Increasing Pb concentrations were generally associated with decreasing 206Pb/207Pb ratios of the contaminated soil cores, offering strong evidence of accumulation of Pb derived from anthropogenic sources. In selected contaminated soil cores, the 206Pb/207Pb ratios tended to increase in the order: carbonate < exchangeable < Fe-Mn oxide < organic < residual fractions. The distribution of the 206Pb/207Pb ratios in the five operationally defined chemical fractions showed that the 206Pb/207Pb ratios generally increased with increasing stability, demonstrating preferential association of anthropogenic Pb with the carbonate, exchangeable, Fe-Mn oxide and organic fractions in the soils.

  1. Early atmospheric metal pollution provides evidence for Chalcolithic/Bronze Age mining and metallurgy in Southwestern Europe.

    PubMed

    Martínez Cortizas, Antonio; López-Merino, Lourdes; Bindler, Richard; Mighall, Tim; Kylander, Malin E

    2016-03-01

    Although archaeological research suggests that mining/metallurgy already started in the Chalcolithic (3rd millennium BC), the earliest atmospheric metal pollution in SW Europe has thus far been dated to ~3500-3200 cal.yr. BP in paleo-environmental archives. A low intensity, non-extensive mining/metallurgy and the lack of appropriately located archives may be responsible for this mismatch. We have analysed the older section (>2100 cal.yr. BP) of a peat record from La Molina (Asturias, Spain), a mire located in the proximity (35-100 km) of mines which were exploited in the Chalcolithic/Bronze Age, with the aim of assessing evidence of this early mining/metallurgy. Analyses included the determination of C as a proxy for organic matter content, lithogenic elements (Si, Al, Ti) as markers of mineral matter, and trace metals (Cr, Cu, Zn, Pb) and stable Pb isotopes as tracers of atmospheric metal pollution. From ~8000 to ~4980 cal.yr. BP the Pb composition is similar to that of the underlying sediments (Pb 15 ± 4 μg g(-1); (206)Pb/(207)Pb 1.204 ± 0.002). A sustained period of low (206)Pb/(207)Pb ratios occurred from ~4980 to ~2470 cal.yr. BP, which can be divided into four phases: Chalcolithic (~4980-3700 cal.yr. BP), (206)Pb/(207)Pb ratios decline to 1.175 and Pb/Al ratios increase; Early Bronze Age (~3700-3500 cal.yr. BP), (206)Pb/(207)Pb increase to 1.192 and metal/Al ratios remain stable; Late Bronze Age (~3500-2800 cal.yr. BP), (206)Pb/(207)Pb decline to their lowest values (1.167) while Pb/Al and Zn/Al increase; and Early Iron Age (~2800-2470 cal.yr. BP), (206)Pb/(207)Pb increase to 1.186, most metal/Al ratios decrease but Zn/Al shows a peak. At the beginning of the Late Iron Age, (206)Pb/(207)Pb ratios and metal enrichments show a rapid return to pre-anthropogenic values. These results provide evidence of regional/local atmospheric metal pollution triggered by the earliest phases of mining/metallurgy in the area, and reconcile paleo-environmental and

  2. A stable lead isotopic investigation of the use of sycamore tree rings as a historical biomonitor of environmental lead contamination.

    PubMed

    Patrick, Gavin J; Farmer, John G

    2006-06-01

    The validity of the use of sycamore (Acer pseudoplatanus) tree-rings for the reconstruction of atmospheric lead pollution histories was investigated. Tree cores spanning 1892-2003 were collected from several sycamores from the eastern shore of Loch Lomond, Scotland, an area with no local point sources of lead emission. The lead concentration and 206Pb/207Pb profiles of the Loch Lomond region cores were compared with corresponding data for the 210Pb-dated loch sediment, and also with data for moss of known age from a Scottish herbarium collection. Two of the seven sycamore cores showed the same lead concentration trend as the lead flux to the loch, the rest having no similarity to either each other or the loch sediment record. Two further sycamore cores showed some similarity in their temporal 206Pb/207Pb trends to those seen in the sediment and moss records, but only in part of their profiles, whilst the 206Pb/207Pb ratios of the other sycamore cores remained relatively unchanged for the majority of the time covered, or exhibited an opposite trend. The 206Pb/207Pb ratios of the tree cores were also mostly higher than those of the previously established records for any given time period. Tree cores covering 1878-2002 were also collected along transects from Wanlockhead and Tyndrum, two areas of former lead mining and smelting associated with distinct 206Pb/207Pb ratios of 1.170 and 1.144, respectively. The Wanlockhead tree cores exhibited a generally decreasing trend in lead concentration with both time and distance from the lead mine. The characteristic 206Pb/207Pb ratio of 1.170 was observed in samples close to the mine but a decrease in the influence of the mine-derived lead was observed in more distant samples. The tree sampled at Tyndrum showed elevated lead concentrations, which decreased with time, and a fairly constant 206Pb/207Pb ratio of 1.15 reflecting input from the mine, features not observed in any other trees along the transect. Overall the data

  3. Early atmospheric metal pollution provides evidence for Chalcolithic/Bronze Age mining and metallurgy in Southwestern Europe.

    PubMed

    Martínez Cortizas, Antonio; López-Merino, Lourdes; Bindler, Richard; Mighall, Tim; Kylander, Malin E

    2016-03-01

    Although archaeological research suggests that mining/metallurgy already started in the Chalcolithic (3rd millennium BC), the earliest atmospheric metal pollution in SW Europe has thus far been dated to ~3500-3200 cal.yr. BP in paleo-environmental archives. A low intensity, non-extensive mining/metallurgy and the lack of appropriately located archives may be responsible for this mismatch. We have analysed the older section (>2100 cal.yr. BP) of a peat record from La Molina (Asturias, Spain), a mire located in the proximity (35-100 km) of mines which were exploited in the Chalcolithic/Bronze Age, with the aim of assessing evidence of this early mining/metallurgy. Analyses included the determination of C as a proxy for organic matter content, lithogenic elements (Si, Al, Ti) as markers of mineral matter, and trace metals (Cr, Cu, Zn, Pb) and stable Pb isotopes as tracers of atmospheric metal pollution. From ~8000 to ~4980 cal.yr. BP the Pb composition is similar to that of the underlying sediments (Pb 15 ± 4 μg g(-1); (206)Pb/(207)Pb 1.204 ± 0.002). A sustained period of low (206)Pb/(207)Pb ratios occurred from ~4980 to ~2470 cal.yr. BP, which can be divided into four phases: Chalcolithic (~4980-3700 cal.yr. BP), (206)Pb/(207)Pb ratios decline to 1.175 and Pb/Al ratios increase; Early Bronze Age (~3700-3500 cal.yr. BP), (206)Pb/(207)Pb increase to 1.192 and metal/Al ratios remain stable; Late Bronze Age (~3500-2800 cal.yr. BP), (206)Pb/(207)Pb decline to their lowest values (1.167) while Pb/Al and Zn/Al increase; and Early Iron Age (~2800-2470 cal.yr. BP), (206)Pb/(207)Pb increase to 1.186, most metal/Al ratios decrease but Zn/Al shows a peak. At the beginning of the Late Iron Age, (206)Pb/(207)Pb ratios and metal enrichments show a rapid return to pre-anthropogenic values. These results provide evidence of regional/local atmospheric metal pollution triggered by the earliest phases of mining/metallurgy in the area, and reconcile paleo-environmental and

  4. Origin of lead in eight Central European peat bogs determined from isotope ratios, strengths, and operation times of regional pollution sources.

    PubMed

    Novák, Martin; Emmanuel, Simon; Vile, Melanie A; Erel, Yigal; Véron, Alain; Paces, Tomás; Wieder, R Kelman; Vanecek, Mirko; Stepánová, Markéta; Brízová, Eva; Hovorka, Jan

    2003-02-01

    Lead originating from coal burning, gasoline burning, and ore smelting was identified in 210Pb-dated profiles through eight peat bogs distributed over an area of 60,000 km2. The Sphagnum-dominated bogs were located mainly in mountainous regions of the Czech Republic bordering with Germany, Austria, and Poland. Basal peat 14C-dated at 11,000 years BP had a relatively high 206Pb/207Pb ratio (1.193). Peat deposited around 1800 AD had a lower 206Pb/207Pb ratio of 1.168-1.178, indicating that environmental lead in Central Europe had been largely affected by human activity (smelting) even before the beginning of the Industrial Revolution. Five of the sites exhibited a nearly constant 206Pb/207Pb ratio (1.175) throughout the 19th century, resembling the "anthropogenic baseline" described in Northern Europe (1.17). At all sites, the 206Pb/207Pb ratio of peat decreased at least until 1980; at four sites, a reversal to more radiogenic values (higher 206Pb/207Pb), typical of easing pollution, was observed in the following decade (1980-1990). A time series of annual outputs for 14 different mining districts dispersing lead into the environment has been constructed for the past 200 years. The production of Ag-Pb, coal, and leaded gasoline peaked in 1900, 1980, and 1980, respectively. In contrast to other European countries, no peak in annual Pb accumulation rates was found in 1900, the year of maximum ore smelting. The highest annual Pb accumulation rates in peat were consistent with the highest Pb emission rates from coal-fired power plants and traffic (1980). Although maximum coal and gasoline production coincided in time, their isotope ratios were unique. The mean measured 206Pb/207Pb ratios of local coal, ores, and gasoline were 1.19, 1.16, and 1.11, respectively. A considerable proportion of coal emissions, relative to gasoline emisions, was responsible for the higher 206Pb/207Pb ratios in the recent atmosphere (1.15) compared to Western Europe (1.10). As in West European

  5. Alpha / Mendeleev Ridge and Chukchi Borderland 40Ar/39Ar Geochronology and Geochemistry: Character of the First Submarine Intraplate Lavas Recovered from the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Mukasa, Samuel B.; Mayer, Larry A.; Aviado, Kimberly; Bryce, Julie; Andronikov, Alex; Brumley, Kelley; Blichert-Toft, Janne; Petrov, Oleg; Shokalsky, Sergey

    2015-04-01

    At least three episodes of magmatic activity have been recognized on the basis of 40Ar/39Ar age determinations in the submarine basaltic samples dredged, drilled or grabbed with a manipulation arm from Alpha / Mendeleev Ridge and Chukchi Borderland of the Arctic Ocean by US Coast Guard Icebreaker Healy, in August-September 2008, and Russian research vessel Captain Dranitsin in August-October 2012: ca. 112 Ma, ca. 100 Ma and ca. 85-73 Ma. Major-oxide and trace-element concentrations, and Pb, Sr, Nd, and Hf isotopic ratios of the recovered lavas provide important constraints on the composition and sources for the original melts. Lavas erupted at ca. 112 Ma (Group 1) have alkali basalt major-oxide compositions. Their low degree of rare-earth-element (REE) fractionation (CeN/YbN = 1.7-2.5), combined with high overall HREE (22-24 times chondrite) and Mg# ~54, suggest derivation from a garnet-free source followed by only minimal crystal fractionation for this group. Pb-Sr-Nd-Hf isotopic systematics of the lavas (206Pb/204Pb = 18.73-18.79; 207Pb/204Pb = 15.54-15.56; 208Pb/204Pb = 38.28-38.35; 143Nd/144Nd = 0.512594-0.512610; 87Sr/86Sr = 0.709458-0.709601; 176Hf/177Hf = 0.283224), together with ratios of highly incompatible trace elements (Th/Ce = 0.09-0.11; Ce/Nb = 2.58-3.09; Th/Nb = 0.24-0.33), point toward a lithospheric source for the magmas. Eruptions at ca. 100 Ma and 85-73 Ma produced two types of lavas: low-Ti tholeiitic basalts - LT, and high-Ti alkali basalts - HT, both assigned to Group 2. This distribution of low- and high-Ti lavas is common in continental flood basalt (CFB) provinces elsewhere, and has been attributed to plume activity in some studies. The trace-element abundance patterns for these Group 2 Arctic lavas are also very similar to those of CFBs elsewhere. Their low degrees of REE fractionation (CeN/YbN = 2.0-3.3) accompanied by progressively decreasing Mg#s (from 53 to 33) suggest a garnet-free source, with the derivative magmas experiencing

  6. Late Cretaceous porphyry Cu and epithermal Cu-Au association in the Southern Panagyurishte District, Bulgaria: the paired Vlaykov Vruh and Elshitsa deposits

    NASA Astrophysics Data System (ADS)

    Kouzmanov, Kalin; Moritz, Robert; von Quadt, Albrecht; Chiaradia, Massimo; Peytcheva, Irena; Fontignie, Denis; Ramboz, Claire; Bogdanov, Kamen

    2009-08-01

    the magmas. 87Sr/86Sr(i) ratios of igneous rocks in the range of 0.70464 to 0.70612 and 143Nd/144Nd(i) ratios in the range of 0.51241 to 0.51255 indicate mixed crustal-mantle components of the magmas dominated by mantellic signatures. The epsilon Hf composition of magmatic zircons (+6.2 to +9.6) also suggests mixed mantellic-crustal sources of the magmas. However, Pb isotopic signatures of whole rocks (206Pb/204Pb = 18.13-18.64, 207Pb/204Pb = 15.58-15.64, and 208Pb/204Pb = 37.69-38.56) along with common inheritance component detected in magmatic zircons also imply assimilation processes of pre-Variscan and Variscan basement at various scales. U-Pb zircon and rutile dating allowed determination of the timing of porphyry ore formation at Vlaykov Vruh (85.6 ± 0.9 Ma), which immediately followed the crystallization of the subvolcanic dacitic bodies at Elshitsa (86.11 ± 0.23 Ma) and the Elshitsa granite (86.62 ± 0.02 Ma). Strontium isotope analyses of hydrothermal sulfates and carbonates (87Sr/86Sr = 0.70581-0.70729) suggest large-scale interaction between mineralizing fluids and basement lithologies at Elshitsa-Vlaykov Vruh. Lead isotope compositions of hydrothermal sulfides (206Pb/204Pb = 18.432-18.534, 207Pb/204Pb = 15.608-15.647, and 208Pb/204Pb = 37.497-38.630) allow attribution of ore-formation in the porphyry and epithermal deposits in the Southern Panagyurishte district to a single metallogenic event with a common source of metals.

  7. Two Distinct Sets of Magma Sources in Cretaceous Rocks From Magnet Cove, Prairie Creek, and Other Igneous Centers of the Arkansas Alkaline Province, USA

    NASA Astrophysics Data System (ADS)

    Duke, G. I.; Carlson, R. W.; Eby, G. N.

    2008-12-01

    Two distinct sets of magma sources from the Arkansas alkaline province (~106-89 Ma) are revealed by Sr-Nd-Pb isotopic compositions of olivine lamproites vs. other alkalic rock types, including carbonatite, ijolite, lamprophyres, tephrite, malignite, jacupirangite, phonolite, trachyte, and latite. Isotopic compositions of diamond-bearing olivine lamproites from Prairie Creek and Dare Mine Knob point to Proterozoic lithosphere as an important source, and previous Re-Os isotopic data indicate derivation from subcontinental mantle lithosphere. Both sources were probably involved in lamproite generation. Magnet Cove carbonatites and other alkalic magmas were likely derived from an asthenospheric source. Lamproite samples are isotopically quite different from other rock types in Sr-Nd-Pb isotopic space. Although three lamproite samples from Prairie Creek have a large range of SiO2 contents (40-60 wt %), initial values of ɛNd (-10 to -13), 206Pb/204Pb (16.61-16.81), 207Pb/204Pb (15.34-15.36), and 208Pb/204Pb (36.57-36.76) are low and similar. Only 87Sr/86Sr(i) displays a wide range in the Prairie Creek lamproites (0.70627-0.70829). A fourth lamproite from Dare Mine Knob has the most negative ɛNd(i) of -19. Lamproite isotope values show a significant crustal component and isotopically overlap subalkalic rhyolites from the Black Hills (SD), which assimilated Proterozoic crust. Six samples of carbonatite, ijolite, and jacupirangite from Magnet Cove and Potash Sulphur Springs exhibit the most depleted Sr-Nd isotopic signatures of all samples. For these rock types, 87Sr/86Sr(i) is 0.70352 - 0.70396, and ɛNd(i) is +3.8 - +4.3. Eight other rock types have a narrow range of ɛNd(i) (+1.9 - +3.7), but a wide range of 87Sr/86Sr(i) (0.70424 - 0.70629). These 14 samples comprise a fairly tight cluster of Pb isotopic values: 206Pb/204Pb (18.22-19.23), 207Pb/204Pb (15.54-15.62), and 208Pb/204Pb (38.38-38.94), suggesting very little crustal assimilation. They are most similar to EM-2

  8. Geochemical and geochronological constraints on the genesis of Au-Te deposits at Cripple Creek, Colorado

    USGS Publications Warehouse

    Kelley, K.D.; Romberger, S.B.; Beaty, D.W.; Pontius, J.A.; Snee, L.W.; Stein, H.J.; Thompson, T.B.

    1998-01-01

    The Cripple Creek district (653 metric tons (t) of Au) consists of Au-Te veins and disseminated gold deposits that are spatially related to alkaline igneous rocks in an Oligocene intrusive complex. Vein paragenesis includes quartz-biotite-K feldspar-fluorite-pyrite followed by base metal sulfides and telluride minerals. Disseminated deposits consist of microcrystalline native gold with pyrite that are associated with zones of pervasive adularia. New 40Ar/39Ar dates indicate that there was a complex magmatic and hydrothermal history. Relatively felsic rocks (tephriphonolite, trachyandesite, and phonolite) were emplaced into the complex over about 1 m.y., from 32.5 ?? 0.1 (1??) to 31.5 ?? 0.1 Ma. A younger episode of phonolite emplacement outside of the complex is indicated by an age of 30.9 ?? 0.1 Ma. Field relationships suggest that at least one episode of mafic and ultramafic dike emplacement occurred after relatively more felsic rocks and prior to the main gold mineralizing event. Only a single whole-rock date for mafic phonolite (which indicated a maximum age of 28.7 Ma) was obtained. However, constraints on the timing of mineralization are provided by paragenetically early vein minerals and K feldspar from the disseminated gold pyrite deposits. Early vein minerals (31.3 ?? 0.1-29.6 ?? 0.1 Ma) and K feldspar (29.8 ?? 0.1 Ma) from the Cresson disseminated deposit, together with potassically altered phonolite adjacent to the Pharmacist vein (28.8 and 28.2 ?? 0.1 Ma), suggest there was a protracted history of hydrothermal activity that began during the waning stages of phonolite and early mafic-ultramafic activity and continued, perhaps intermittently, for at least 2 m.y. Estimated whole-rock ??18O values of the alkaline igneous rocks range from 6.4 to 8.2 per mil. K feldspar and albite separates from igneous rocks have lead isotope compositions of 206Pb/204Pb = 17.90 to 18.10, 207Pb/204Pb = 15.51 to 15.53, and 208Pb/204Pb = 38.35 to 38.56. These isotopic

  9. A composite, isotopically-depleted peridotite and enriched pyroxenite source for Madeira magmas: Insights from olivine

    NASA Astrophysics Data System (ADS)

    Gurenko, Andrey A.; Geldmacher, Jörg; Hoernle, Kaj A.; Sobolev, Alexander V.

    2013-06-01

    The Madeira and Canary island/seamount chains represent two adjacent hotspot tracks in the eastern North Atlantic, which were derived from mixed peridotite-pyroxenite mantle sources. They possess systematically different Sr-Nd-Pb, Os and Hf isotope signatures, implying mixing of DMM-, HIMU- and EM-type components from different mantle lithologies. The lithological nature of these postulated mantle endmembers (e.g., if formed by peridotite, pyroxenite and/or eclogite) is still a subject of debate. We studied the chemical composition of olivine phenocrysts (focusing on their Ni, Mn and Ca concentrations) from the lavas covering the entire volcanic history of the Madeira Archipelago (~ 0-5 Ma). We demonstrate that Ni × FeO/MgO and Mn/FeO ratios and Ca-concentrations of olivine correlate with Sr, Nd and Pb isotopic compositions of their host lavas. The amounts of peridotite- and pyroxenite-derived melt fractions in the parental Madeira magmas were inferred from olivine compositions and independently confirmed by modeling of two-component source melting using trace elements. Our calculations demonstrate that the amount of recycled crust (= eclogite) in the Madeira magma source varies but does not exceed ~ 10%. Strong linear relationships between chemical composition of olivine and radiogenic isotopes of the host lavas allow us to determine the isotopic composition of peridotite and pyroxenite endmembers of the Madeira hotspot. The peridotite endmember has a highly depleted isotopic composition 87Sr/86Sr = 0.7022-0.7026, 143Nd/144Nd = 0.5132-0.5135, 206Pb/204Pb = 17.4-18.6, 207Pb/204Pb = 15.4-15.49, and 208Pb/204Pb = 36.8-38.2, whereas the pyroxenite endmember has an enriched composition 87Sr/86Sr = 0.7031-0.7035, 143Nd/144Nd = 0.5127-0.5130, 206Pb/204Pb = 19.9-21.3, 207Pb/204Pb = 15.59-15.69, and 208Pb/204Pb = 39.6-41.2. Our new data confirm the existence of recycled (pyroxenitic) lithology in the Madeira magma source that was previously interpreted to represent

  10. Transport and selective uptake of radium into natural clay minerals

    NASA Astrophysics Data System (ADS)

    Hidaka, Hiroshi; Horie, Kenji; Gauthier-Lafaye, Françoise

    2007-12-01

    Understanding of the environmental behavior of Ra is important from the viewpoint of the long-termed repository safety of radioactive waste, but investigation of Ra behavior in natural environment is difficult to detect. We found isotopic evidence of Ra transportation and its selective uptake into clay minerals from Pb isotopic analyses. Illite grains found in calcite veins included in sandstone near the Oklo uranium deposit, Republic of Gabon, show extremely low 207Pb/ 206Pb (˜ 0.0158) isotopic ratios. Although the Pb isotopic ratios of calcite and quartz coexisting with illite indicate the formation age of each component, those of illite do not. In addition, illite grains having low 207Pb/ 206Pb isotopic ratios contain a strongly large amount of Ba (1230 to 6010 ppm) in contrast with low contents of Ba in calcite and quartz (< 0.26 ppm). Considering the chemical similarity between Ba and Ra, the 207Pb/ 206Pb isotopic data suggest an excess of 206Pb due to selective adsorption of 226Ra (and also Ba) into illite grains. This is a very rare example to show evidence of the selective adsorption behavior of Ra from the isotopic excesses of 206Pb, although the adsorption ability of Ra itself in nature was largely reported.

  11. Using biochemical and isotope geochemistry to understand the environmental and public health implications of lead pollution in the lower Guadiana River, Iberia: a freshwater bivalve study.

    PubMed

    Company, R; Serafim, A; Lopes, B; Cravo, A; Shepherd, T J; Pearson, G; Bebianno, M J

    2008-11-01

    Lead is a natural component of aquatic ecosystems with no known biological role and is highly toxic. Its toxicity stems from its ability to mimic biologically important metals and to produce membrane damage through lipid peroxidation (LPO). Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme, delta-aminolevulinic acid dehydratase (ALAD), the activity of which is markedly inhibited by lead. The purpose of this work was to study the levels and effects of lead pollution (responses of ALAD and oxidative stress biomarker LPO) in the freshwater bivalve Corbicula fluminea along the lower Guadiana River (Portugal and Spain); a major river system impacted by historic mining pollution and more recent anthropogenic inputs. The results show that the enzymatic activity of ALAD is negatively correlated with the total Pb concentration of the whole tissue suggesting that ALAD has considerable potential as a biomarker of lead exposure in C. fluminea. To identify the sources of lead to which bivalves have been exposed, high precision (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)/Pb ratios for C. fluminea confirm that historical mining activities in the Iberian Pyrite Belt are the dominant source of lead pollution in the lower Guadiana River. The isotope patterns however exhibit marked seasonal and geographic variation in response to rainfall and river water management. Locally, other anthropogenic sources of lead have been detected in C. fluminea close to population centres, thus adding to its versatility as a freshwater bio-indicator. Overall, the study highlights the value of natural ecosystems as monitors of water quality and their importance for public health assessment and surveillance.

  12. A volcanic district between the Hoggar uplift and the Tenere Rifts: Volcanology, geochemistry and age of the In-Ezzane lavas (Algerian Sahara)

    NASA Astrophysics Data System (ADS)

    Yahiaoui, Rachid; Dautria, Jean-Marie; Alard, Olivier; Bosch, Delphine; Azzouni-Sekkal, Abla; Bodinier, Jean-Louis

    2014-04-01

    The In-Ezzane volcanic district (EZD), located at the triple junction of Algeria, Niger and Libya belongs to the Eastern Hoggar, covers 350 km2 and includes 9 volcanic edifices that are probably aligned along NW-SE faults, parallel to the Tafassasset valley. The low volume (0.7 and 1 km3) of emitted lavas, the similar morphology of the monogenic cones and the lack of differentiated rocks indicate that the volcanic activity of the EZD was restricted in time and volume. The new K-Ar age (i.e. 2.86 ± 0.07 Ma) indicates that the EZD is contemporaneous with the last alkali volcanism paroxysm in Hoggar and with the nearby Libyan volcanics. The EZD alkali basalts (mainly basanite) show a remarkable homogeneous compositions both in major elements (44.8 ⩽ SiO2 ⩽ 45.8 wt.%; 5.2 ⩽ (Na2O + K2O) ⩽ 6.2 wt.%), trace elements (4.3 ⩽ Th ⩽ 5.5 ppm; 34.7 ⩽ La ⩽ 44.7 ppm; 16.1 < La/Yb(N) < 21.6) and radiogenic isotopes (0.70285 < 87Sr/86Sr < 0.70303; 0.51298 < 143Nd/144Nd < 0.51301; (19.212 < 206Pb/204Pb < 19.340, 15.589 < 207Pb/204Pb < 15.602 and 38.834 < 208Pb/204Pb < 38.903). Relative to the Hoggar alkaly basalts the EZD basalts appear systematically impoverished in incompatible elements and show a depleted signature both in Sr and Nd isotopes (almost MORB-like). The Pb isotopes are relatively enriched and intermediate between tholeiites and alkali basalts of the Hoggar. This unusual geochemical signature, is uneasy to reconcile with the known characteristics of the Hoggar swell, and would rather fingerprint a circum cratonic mantle lying beneath the west border of the Murzuq craton (Libya).

  13. Solving petrological problems through machine learning: the study case of tectonic discrimination using geochemical and isotopic data

    NASA Astrophysics Data System (ADS)

    Petrelli, Maurizio; Perugini, Diego

    2016-10-01

    Machine-learning methods are evaluated to study the intriguing and debated topic of discrimination among different tectonic environments using geochemical and isotopic data. Volcanic rocks characterized by a whole geochemical signature of major elements (SiO2, TiO2, Al2O3, Fe2O3T, CaO, MgO, Na2O, K2O), selected trace elements (Sr, Ba, Rb, Zr, Nb, La, Ce, Nd, Hf, Sm, Gd, Y, Yb, Lu, Ta, Th) and isotopes (206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, 87Sr/86Sr and 143Nd/144Nd) have been extracted from open-access and comprehensive petrological databases (i.e., PetDB and GEOROC). The obtained dataset has been analyzed using support vector machines, a set of supervised machine-learning methods, which are considered particularly powerful in classification problems. Results from the application of the machine-learning methods show that the combined use of major, trace elements and isotopes allows associating the geochemical composition of rocks to the relative tectonic setting with high classification scores (93 %, on average). The lowest scores are recorded from volcanic rocks deriving from back-arc basins (65 %). All the other tectonic settings display higher classification scores, with oceanic islands reaching values up to 99 %. Results of this study could have a significant impact in other petrological studies potentially opening new perspectives for petrologists and geochemists. Other examples of applications include the development of more robust geothermometers and geobarometers and the recognition of volcanic sources for tephra layers in tephro-chronological studies.

  14. Impact of Dust from Ore Processing Facilities on Rain Water Collection Tanks in a Tropical Environment--The Obvious Source "Ain't Necessarily So".

    PubMed

    Gulson, Brian; Korsch, Michael; Bradshaw, Anthony

    2016-02-01

    Concerns have been expressed that dust from the minerals processing facilities at Karumba Queensland Australia have resulted in elevated lead (Pb) concentrations in rain water tanks. The ores derived from the Century mine some 304 km from the port. High precision Pb isotopic measurements on environmental samples have been undertaken to evaluate the source of Pb in rainwaters and acid digests from roof wipes and gutter wipes. There does not appear to be any relationship between sample location and the processing facility but samples from the area subject to the prevailing winds show the highest contribution of Century Pb. All gutter wipes (82 to 1270 µg Pb/wipe) have contributions of Century ore ranging from 87% to 96%. The contribution of Century ore to five roof wipes (22 to 88 µg Pb/wipe) ranges from 89% to 97% and in the other two samples there is a mix of Century and Broken Hill Pb. Three of the seven rainwater have contributions of Century ore Pb ranging from 33% to 75%. Two of the other four rainwater samples have the highest water Pb concentrations of 88 and 100 µg/L and their isotopic data show Broken Hill Pb contributions ranging from 77% to 80%. The source of the Broken Hill Pb is probably from the galvanized roofing material and/or brass fittings in the rainwater tanks. The discrimination between various sources is only detectable using high precision (204)Pb-based isotopic ratios and not the now common inductively coupled plasma mass spectrometry (ICP-MS ) data presentations of the higher abundance isotopes (208)Pb, (207)Pb and (206)Pb. Isotopic results for the waters demonstrate that apportioning blame where there is an obvious point source may not always be the correct conclusion. Nevertheless the isotopic data for the gutter wipes indicates that there was widespread contamination from the processing facilities throughout the town. PMID:26907319

  15. Syn-collisional granitoids in the Qilian Block on the Northern Tibetan Plateau: A long-lasting magmatism since continental collision through slab steepening

    NASA Astrophysics Data System (ADS)

    Huang, Hui; Niu, Yaoling; Mo, Xuanxue

    2016-03-01

    In this paper we present a new model that can explain the large zircon age spectrum of ~ 510 - 420 Ma within a single sample from the Gangcha (Gcha) biotite granodiorite and the Huangyuan (HY) two-mica monzogranite on the northern Tibetan Plateau. The large age spread recorded in zircons is characteristic of granitoid samples from the studied region, which is best explained by the long-lasting magmatism since the onset of continental collision at ~ 500 Ma, followed by slab steepening and the ultimate slab break-off at ~ 450 Ma. These granitoids have a large major and trace element compositional variation, but limited initial Sr (ISr[450] = 0.709 to 0.715), Nd (ԐNd[450] = - 6.5 to - 3.7), Hf (ԐHf[450] = - 4.3 to 1.5) and Pb (206Pb/204Pb[450] = 17.70 to 17.17; 207Pb/204Pb[450] = 15.60 to 15.69; 208Pb/204Pb[450] = 38.04 to 38.73) isotopic variation. The small negative whole rock ԐNd[450] and ԐHf[450] values are most consistent with the granitoid source being dominated by subducted seafloor materials. The inherited zircons with large negative ԐHf[450] values (e.g. - 50) are indicative of input from the lower continental crust and subducted sediments. The correlated variations among major elements, trace elements and radiogenic isotopes are best interpreted as reflecting melting-induced mixing of a compositionally heterogeneous source with superimposed effect of varying extent of fractional crystallization and crustal assimilation. The inherited zircons of Palaeo-Proterozoic age and the Archean crustal model ages signify the involvement of ancient basement rocks.

  16. Lead Isotope Measurement by Lead Double Spike and Thallium Spike Using MC-ICP-MS and TIMS - a Comparison Using Basaltic Samples

    NASA Astrophysics Data System (ADS)

    Taylor, R. N.; Ishizuka, O.

    2001-12-01

    Multi-collector ICP-MS has provided a new level of precision to lead isotope analysis using Thallium addition as an internal mass bias monitor. Further enhancement of precision has been achieved by the application of double lead spike to measurement procedures. In this study, we directly compare results using thallium addition and the new SBL74 double lead spike on both TIMS and MC-ICP-MS (Micromass IsoProbe). The comparisons are performed using standard Pb solutions and basaltic matrix-bearing solutions. Analyses of standards measured over 8 analytical sessions using the thallium spike method are reproducible to within 100 ppm for 206Pb/204Pb, 130 ppm for 207Pb/204Pb and 220 ppm (2sd) for 208Pb/204Pb. If the ratios for individual analytical sessions are normalised to the SRM981{day average}/SRM981true the increasing error with greater mass difference of the ratio is eliminated and all ratios are less than ±85 ppm. This implies that variability between the Tl and Pb mass bias factors on a day-to-day basis is the cause of increasing imprecision with mass difference. Double spike MC-ICP-MS is found to produce similar levels of precision to the Tl method for standards. However, the decreasing precision with increasing mass difference is greatly reduced, indicating that the correlation is due to Tl and Pb differences. With basaltic matrix samples with a single anion exchange separation, the effects of Tl-Pb differential mass bias are slightly exaggerated. We present the results from mixtures of SRM981 with Pb-free Fe measured using MC-ICP-MS using Tl and double spike mass bias correction, to replicate the basaltic matrix analyses.

  17. Lead and sulfur isotopes of Guarn Halfaya and Bou Grine deposits associated to salt dome cap rocks (Diapirs zone, Northern Tunisia): sources of metals and genetic model

    NASA Astrophysics Data System (ADS)

    Jemmali, N.; Souissi, F.; Carranza, E. J. M.; Vennemann, T. W.

    2012-04-01

    The Pb-Zn ores districts at Guarn Halfaya and Bou Grine are hosted mainly by the dolostones in the contact breccias between Triassic and Upper Cretaceous and by Upper Cretaceous limestones. The mineralization occurs as lenticular, impregnations, substitutions, replacements, stratiform, vein, dissemination, and stockwork. A complex polymetallic sulfide assemblage typifies the main ore stage, dominated by sphalerite and galena, pyrite with minor chalcopyrite, arsenopyrite, and sulfosalt (grey copper). Limestone, barite and celestite dominate the gangue, with lesser calcite. Barite and celestite intergrown with main ore-stage sulfides of Oum Edeboua has δ34S values of 12.7 to 15.0 ‰, consistent with the derivation of sulfate from Triassic evaporites form the study area (12.8<δ34S<14.0 ‰). The δ34S values for sulfides of the both study area range from 2.6 to 9.5 ‰. These positive δ34S values are likely due to abiotic thermally-driven abiotic sulfate reduction (TSR) of Triassic sulfates at depth. However, the presence of bacterial relics suggests involvement of bacterially-mediated sulfate reduction (BSR). The lead isotope composition is homogeneous with 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratio ranging between from 18.723 to 18.783, 15.667 to 15.685, and 38.806 to 38.889, respectively, and plot between the upper crust and orogene curves of Zartman and Doe (1981) which imply involvement of a well-mixed multi-source reservoir of Pb at depth. The syn-diagenetic mineralization in the Bahloul Formation and the calculate of model age suggest a Late Cretaceous age, correspond to a NE-SW to ENE-WSS regional extensional tectonic events, which likely favored migration of mineralizing fluids and eventual deposition at Guarn Halfaya and Bou Grine.

  18. Mt. St. Augustine, Alaska: Geochemical evolution of an eastern Aleutian volcanic center

    SciTech Connect

    Johnson, K.E. . Dept. of Geology); Harmon, R.S. . Kingsley Dunham Centre); Moorbath, S. . Dept. of Earth Sciences); Sigmarsson, O. )

    1993-04-01

    Mt. St. Augustine is a calc-alkaline Quaternary volcano, situated within Cook Inlet, Alaska. The island is composed of low- to medium-K andesite and dacite domes and pyroclastic flows. Major element variations indicate the magmatic evolution is dominantly influenced by fractionation and magma-mixing processes. Incompatible element and isotopic compositions suggest that despite its continental location, crustal assimilation is not significant factor in magmatic evolution. Alkali contents for Augustine are generally lower than elsewhere in the Aleutians (e.g. Augustine Cs/Rb = 0.016--0.024, K/Rb = 372--553; Aleutians Cs/Rb = 0.016--0.17, K/Rb = 231--745). Sr- and Nd-isotope ratios encompass narrow ranges ([sup 87]Sr/[sup 86]Sr = 0.70317--0.70343; [sup 143]Nd/[sup 144]Nd = 0.513011--0.513085), characteristic of uncontaminated mantle-derived melts. U-Th disequilibrium isotopic values also indicate little or no assimilation of evolved continental crust. Pb-isotopic ranges are also relatively restricted ([sup 206]Pb/[sup 204]Pb = 18.62--18.82; [sup 207]Pb/[sup 204]Pb = 15.54--15.57; [sup 208]Pb/[sup 204]Pb = 38.18--38.34) and comparison with north Pacific enriched (OIB) and depleted (MORB) mantle sources suggest the incorporation of only a small percentage of subducted terrigenous sediments. A model for Augustine magma genesis is proposed where parental magmas are generated by 5--20% partial melting of a lherzolite mantle with up to a 5% subducted terrigenous sediment component. The major influence of the thickened continental crust is to prevent the ascent and eruption of basaltic magma. The data exhibit no temporal variations, indicating that the magmatic system which produced the historic eruptions is well established.

  19. A proposed new approach and unified solution to old Pb paradoxes

    NASA Astrophysics Data System (ADS)

    Castillo, Paterno R.

    2016-05-01

    One of the most remarkable features of many and, perhaps, all oceanic basalts is that their Pb isotopic ratios (206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb) are too radiogenic to be coming from the undifferentiated mantle or bulk silicate Earth. This has created three major concerns in the behavior of U, Th and Pb in the Earth's mantle that have been termed the Pb paradoxes. These are the unexpectedly long time-integrated high U/Pb (1st paradox), long time-integrated low Th/U (2nd paradox) and constant Ce/Pb and Nb/U (3rd paradox) in the mantle sources of oceanic basalts. The origins of such unexpected ratios have been the object of intense studies that produced several highly significant, but generally individualized results during the last four decades. Detailed analysis of available data shows that the paradoxes are closely interrelated as they all pertain to the mantle and have many common characteristic features. Thus, the Pb paradoxes constitute a system of equations that must be solved all together as each solution must satisfy every equation in the system. For example, compositional data for the voluminous mid-ocean ridge basalts (MORB) show that the 1st and 2nd paradoxes exhibit a long time-integrated enrichment of U and the Th/U and Nb/Th ratios are also constant. A single solution to simultaneously explain the paradoxes in MORB is possible if recycled materials with variable enrichments in incompatible trace elements, particularly U and its daughter Pb* plus Nb, Ce, and Th are added to or mixed with the depleted upper mantle. Significantly, a similar binary mixing solution has been proposed for the Pb paradoxes in ocean island basalts.

  20. Basalt of Summit Creek: Eocene Magmatism Associated with Farallon Slab Break Off

    NASA Astrophysics Data System (ADS)

    Kant, L. B.; Tepper, J. H.; Eddy, M. P.

    2015-12-01

    In the Pacific Northwest the Early-Middle Eocene was a time of widespread magmatism and tectonic reorganization that included accretion of the Siletzia terrane, Challis volcanism, and establishment of the modern Cascade arc. Although individual events are well documented our knowledge of the underlying tectonic framework is incomplete. To better understand the tectonic changes that occurred during this interval we studied the ~48 Ma Basalt of Summit Creek (BSC), a 1500m section of lavas located south of Mt. Rainier that erupted during the critical time period between the docking of Siletzia and the initiation of the modern Cascade arc. The BSC consists mainly of tholeiitic basalts (wt. % SiO2 = 45.54-63.45, Mg# = 0.68-0.30) with EMORB traits (La/YbN = 1.2-5.9; 206Pb/204Pb = 19.005-19.102; 207Pb/204Pb = 15.538-15.593; 208Pb/204Pb = 38.560-38.714). These lavas lack arc signatures (e.g., HFSE depletions) but overlap in elemental and isotopic composition with oceanic basalts of the Crescent Formation (part of Siletzia) located ~100 km to the west. We suggest that emplacement of lavas that lack arc traits in what was the forearc was a response to break off of the Farallon slab, which occurred as a result of the accretion of Siletzia at ~49 Ma (Wells et al., 2014). Break off opened a gap in the subducted slab, allowing upwelling and subsequent decompression melting. BSC lavas are consistent in age, location and composition with this model. After break off subduction resumed outboard of Siletzia, initiating the Cascade arc. Thus, BSC provides evidence of Farallon slab break off and furthers our understanding of the tectonic transition from widespread magmatism of the Early-Middle Eocene to the Cascade arc.

  1. Impact of Dust from Ore Processing Facilities on Rain Water Collection Tanks in a Tropical Environment--The Obvious Source "Ain't Necessarily So".

    PubMed

    Gulson, Brian; Korsch, Michael; Bradshaw, Anthony

    2016-02-22

    Concerns have been expressed that dust from the minerals processing facilities at Karumba Queensland Australia have resulted in elevated lead (Pb) concentrations in rain water tanks. The ores derived from the Century mine some 304 km from the port. High precision Pb isotopic measurements on environmental samples have been undertaken to evaluate the source of Pb in rainwaters and acid digests from roof wipes and gutter wipes. There does not appear to be any relationship between sample location and the processing facility but samples from the area subject to the prevailing winds show the highest contribution of Century Pb. All gutter wipes (82 to 1270 µg Pb/wipe) have contributions of Century ore ranging from 87% to 96%. The contribution of Century ore to five roof wipes (22 to 88 µg Pb/wipe) ranges from 89% to 97% and in the other two samples there is a mix of Century and Broken Hill Pb. Three of the seven rainwater have contributions of Century ore Pb ranging from 33% to 75%. Two of the other four rainwater samples have the highest water Pb concentrations of 88 and 100 µg/L and their isotopic data show Broken Hill Pb contributions ranging from 77% to 80%. The source of the Broken Hill Pb is probably from the galvanized roofing material and/or brass fittings in the rainwater tanks. The discrimination between various sources is only detectable using high precision (204)Pb-based isotopic ratios and not the now common inductively coupled plasma mass spectrometry (ICP-MS ) data presentations of the higher abundance isotopes (208)Pb, (207)Pb and (206)Pb. Isotopic results for the waters demonstrate that apportioning blame where there is an obvious point source may not always be the correct conclusion. Nevertheless the isotopic data for the gutter wipes indicates that there was widespread contamination from the processing facilities throughout the town.

  2. Petrogenesis and tectonic setting of the early Mesozoic Xitian granitic pluton in the middle Qin-Hang Belt, South China: Constraints from zircon U-Pb ages and bulk-rock trace element and Sr-Nd-Pb isotopic compositions

    NASA Astrophysics Data System (ADS)

    Wu, Qianhong; Cao, Jingya; Kong, Hua; Shao, Yongjun; Li, Huan; Xi, Xiaoshuang; Deng, Xuantong

    2016-10-01

    The Xitian pluton in southeast Hunan province is one of the early Mesozoic (Indosinian) granitic plutons in the South China Block. It is composed of biotite adamellite with K-feldspar megacrysts, biotite adamellite, and biotite granite that have U-Pb zircon ages of 229.9 ± 1.4 Ma, 223.6 ± 1.3 Ma, and 224.0 ± 1.4 Ma, respectively. The Indosinian granitoids in the Xitian pluton belong to S-type granites, with highly radiogenic initial 87Sr/86Sr ratios (0.71397-0.71910), negative εNd(t) values ranging from -10.1 to -9.4, and old Nd model ages (1858-1764 Ma). They are enriched in radiogenic Pb isotopes, with (206Pb/204Pb)t ranging from 18.130 to 18.903, (207Pb/204Pb)t from 15.652 to 15.722, and (208Pb/204Pb)t from 38.436 to 39.037, respectively. These features indicate that the granitoidswithin the Xitian pluton were formed from magmas generated by remelting of metapelite and metapsammite of the Paleoproterozoic metamorphic basement at temperatures of ca. 800 °C, with low oxygen fugacity. The Sr-Nd isotopic compositions of the rocks from Xitian pluton indicate that the granitic magmas were mixed with less than 10% mantle-derived magmas. We suggest that the Xitian pluton was emplaced in an extensional tectonic setting related to release of compressional stresses within the thickened crust during the early Mesozoic.

  3. Chemical constraints on the petrogenesis of mildly alkaline lavas from Vestmannaeyjar, Iceland: the Eldfell (1973) and Surtsey (1963 1967) eruptions

    NASA Astrophysics Data System (ADS)

    Furman, Tanya; Frey, Fred A.; Park, Kye-Hun

    1991-03-01

    The Vestmannaeyjar archipelago is composed of alkalic lavas erupted at the southern end of the active, southward propagating, Eastern Volcanic Zone. Recent eruptions include the most primitive (Surtsey) and most evolved (Eldfell) compositions found in this area. We studied time-stratigraphic sample suites from both eruptions to characterize the magmatic environment of Vestmannacyjar. All samples are nearly homogeneous in radiogenic isotopic ratios (87Sr/86Sr 0.70304 to 0.70327;143Nd/144Nd 0.51301 to 0.50307;206Pb/204Pb 18.96 to 19.18;207Pb/204Pb 15.50 to 15.53;208Pb/204Pb 38.47 to 38.76; KH Park and A Zindler, in preparation). Compositional trends of lavas from the two eruptions are not consistent with fractionation in a near-surface environment, but indicate rather moderate pressure evolution of small magma batches. At Eldfell, mugearite lavas can be modeled by 30% closed-system fractional crystallization of olivine+plagioclase+clinopyroxene+Fe-Ti oxides from parental hawaiite. The phase proportions are consistent with an experimentally determined moderate pressure (8 kbar) cotectic in mildly alkaline systems (Mahood and Baker 1986). Compositional variations of Surtsey lavas can be modeled by crystallization of clinopyroxene+olivine+plagioclase+minor Fe-Ti oxides. The presence of sodic plagioclase megacrysts and clinopyroxene with ˜8 wt% Al2O3 in xenoliths from Surtsey lavas are consistent with a moderate pressure fractionation event. Based on major-element and REE data the most primitive Surtsey lavas formed by small degrees of melting of a lherzolite source. The alkaline nature of Vestmannaeyjar lavas is not the result of assimilation of lower crustal melts (cf. Oskarsson et al. 1985; Steinthorsson et al. 1985).

  4. Mantle heterogeneities beneath the Northeast Indian Ocean as sampled by intra-plate volcanism at Christmas Island

    NASA Astrophysics Data System (ADS)

    Taneja, Rajat; Rushmer, Tracy; Blichert-Toft, Janne; Turner, Simon; O'Neill, Craig

    2016-10-01

    The intra-plate region of the Northeast Indian Ocean, located between the Ninetyeast Ridge and the North West Shelf of Australia, contains numerous submerged seamounts and two sub-aerially exposed volcanic island groups. While the Cocos (Keeling) Archipelago is a coral atoll, Christmas Island is the only sub-aerially exposed volcanic island and contains Late Cretaceous, Eocene and Pliocene lavas. The lavas are predominantly basaltic in composition, except for one sampled flow that is trachytic. Although the evolution of the western margin of Australia, and the seismicity in the intra-plate region, has received considerable attention, the origin of the seamount province in the Northeast Indian Ocean is still a matter of debate. In order to constrain the origin of volcanism on Christmas Island and the associated Seamount Province we analysed 14 Christmas Island samples for major and trace element abundances and 12 of these for Nd, Hf and Pb isotope compositions. The trace element patterns of the lavas are similar to many ocean island basalts, while high 208Pb/204Pb and 207Pb/204Pb at a given 206Pb/204Pb suggest affiliation with the DUPAL anomaly. The reconstructed position of Christmas Island during the Eocene (44-37 Ma) places the island in close proximity to the (present-day) upper mantle low-seismic velocity anomalies. Moreover, an enriched mantle (EM-2) type component in addition to the DUPAL anomaly is observed in the Eocene volcanic phase. The younger Pliocene (~ 4 Ma) sequences at Christmas Island are inferred to be the product of partial melting of existing material induced by lithospheric flexure.

  5. Determination of Cd, Cr, Hg and Pb in plastics from waste electrical and electronic equipment by inductively coupled plasma mass spectrometry with collision-reaction interface technology.

    PubMed

    Santos, Mirian C; Nóbrega, Joaquim A; Cadore, Solange

    2011-06-15

    A procedure based on the use of a quadrupole inductively coupled plasma-mass spectrometer equipped with a collision-reaction interface (CRI) for control of spectral overlap interferences was developed for simultaneous determination of Cd, Cr, Hg, and Pb in plastics from waste electrical and electronic equipment (WEEE). The injection of H(2) and He (80 and 60 mL min(-1), respectively) into the sampled plasma, colliding and reacting with potentially interfering polyatomic ions, allows interference-free determination of chromium via its isotopes (52)Cr and (53)Cr that are freed from overlap due to the occurrence of (40)Ar(12)C(+), (40)Ar(12)C(1)H(+), (36)S(16)O(+) or (1)H(36)S(16)O(+). Cadmium, Hg and Pb were directly determined via their isotopes (110)Cd, (111)Cd, (112)Cd, (199)Hg, (200)Hg, (201)Hg, (202)Hg, (206)Pb, (207)Pb, and (208)Pb, without using CRI. The CRI can be quickly activated or deactivated before each analyte measurement. Limits of detection for (52)Cr were 0.04 or 0.14 μg L(-1) with He or H(2) injected in CRI. Cadmium and Pb have LODs between 0.02 and 0.08 μg L(-1) and Hg had 0.93-0.98 μg L(-1), without using CRI. Analyte concentrations for samples varied from 16 to 43, 1 to 11, 4 to 12, and 5 to 13 mg kg(-1) for Cr, Cd, Hg and Pb, respectively.

  6. Geochemical and Sr-Nd-Pb-O isotope composition of granitoids of the Early Cretaceous Copiapó plutonic complex (27°30'S), Chile

    NASA Astrophysics Data System (ADS)

    Marschik, Robert; Fontignie, Denis; Chiaradia, Massimo; Voldet, Pia

    2003-10-01

    Early Cretaceous plutonic rocks exposed south of Copiapó form part of the Coastal Batholith of northern Chile. These rocks intrude arc-derived volcanic and volcaniclastic rocks and marine limestones that were deposited in the Early Cretaceous Atacama backarc basin. The Copiapó plutonic complex consists mainly of calc-alkaline, medium- to coarse-grained diorite, granodiorite, tonalite, monzodiorite, and quartz monzonite. The plutonic rocks are subalkaline to alkaline, metaluminous, magnetite-series, volcanic arc, I-type granitoids. Batholithic magmas are a heat, potential fluid, metal, and sulphur source for the hydrothermal iron oxide-rich Cu-Au mineralization in the Candelaria-Punta del Cobre district. Ore-related hydrothermal alteration affected large portions of the Copiapó complex. The least altered batholithic rocks have initial 87Sr/ 86Sr of 0.703070-0.703231; initial 143Nd/ 144Nd of 0.512733-0.512781; and 206Pb/ 204Pb, 207Pb/ 204Pb, and 208Pb/ 204Pb of 18.428-18.772, 15.550-15.603, and 38.127-38.401, respectively. The δ18O values for these rocks range from +6.9 to +8.6‰. Isotope signatures and trace element distributions suggest that the magmas are mantle derived. A subduction fluid-modified mantle source may explain the geochemical characteristics of the Copiapó complex. The ascent of magmas occurred along deep-rooted structures without significant crustal contamination, though minor contamination by relatively young (e.g. Jurassic) igneous rocks during ascent is possible. Intrusive rocks with high-K to shoshonitic characteristics probably represent residual liquids of less evolved magmas. The regional geologic context suggests that the plutons of the Copiapó complex were emplaced at a relatively shallow crustal level of 2-3 km.

  7. Plume-orogenic lithosphere interaction recorded in the Haladala layered intrusion in the Southwest Tianshan Orogen, NW China

    NASA Astrophysics Data System (ADS)

    He, Peng-Li; Huang, Xiao-Long; Xu, Yi-Gang; Li, Hong-Yan; Wang, Xue; Li, Wu-Xian

    2016-03-01

    The plume-orogenic lithosphere interaction may be common and important for the generation of large igneous provinces. The information regarding such a process is recorded by the Haladala gabbroic intrusion (~300 Ma), the largest layered ultramafic-mafic intrusion hosting V-Ti magnetite deposits in the Southwest Tianshan Orogen, NW China. The Haladala gabbros exhibit unfractionated chondrite-normalized rare earth element patterns with negative Nb and Ta anomalies and positive Pb anomaly on the primitive mantle-normalized multielement variation diagram. They are characterized by low initial Sr isotopes, slightly decoupled but high positive bulk rock ɛNd(t) and ɛHf(t), and high 207Pb/204Pb and 208Pb/204Pb relative to 206Pb/204Pb, delineating a DUPAL signature in the sources. The Haladala gabbros cannot be arc or postcollisional magmatism, given the lack of hydrous minerals and low K contents, respectively. This is further supported by the relatively low oxygen fugacity required for the gradual enrichment of V-Ti magnetite during the magma fractionation and by an overall anhydrous mantle source suggested by troctolite mineral assemblage (olivine + plagioclase). The emplacement age of the Haladala gabbros is identical to that of the Wajilitag kimberlites in the Tarim's interior, which have been interpreted as the first magmatic expression of the Tarim mantle plume. We thus propose that the Haladala gabbroic intrusion was generated in a hybrid geodynamic setting in which the Southwest Tianshan Orogen was impacted by an upwelling mantle plume. In this sense, the Haladala layered gabbroic intrusion records the early phase of magmatism of the Tarim plume, which was preferentially emplaced in a lithospheric weak zone.

  8. Cenozoic alkali basalts from Jingpohu, NE China: The role of lithosphere asthenosphere interaction

    NASA Astrophysics Data System (ADS)

    Yan, Jun; Zhao, Jian-Xin

    2008-06-01

    The geochemistry of Late Cenozoic volcanic rocks from Jingpohu, NE China, provides important constraints on the petrogenesis of continental alkali basalts and lithospheric evolution in the eastern Central Asian Orogenic Belt (CAOB). Miocene-Pleistocene and Holocene basalts from Jingpohu show alkali affinities and are characterized by Ocean Island Basalt (OIB)-like REE and trace element patterns somehow resembling Holocene potassic rocks from Wudalianchi which are considered to be derived from ancient enriched lithospheric mantle. These basalts show depleted Sr-Nd isotopic compositions ( 87Sr/ 86Sr = 0.7039-0.7046, ɛNd = 1.3-6.0) and Dupal-like but unradiogenic Pb isotopic signatures ( 206Pb/ 204Pb = 17.54-17.94, 207Pb/ 204Pb = 15.45-15.54, 208Pb/ 204Pb = 37.71-38.07), comparable to the OIB. The combined geochemical and isotopic signatures are consistent with magma source mixing between a Focal Zone (FOZO)-like asthenospheric mantle component (characterized by enriched Pb and depleted Sr-Nd isotopic compositions) and an isotopically enriched EM1-type subcontinental lithospheric mantle component. Lithospheric thickness inferred from alkali basalts from different regions implies a progressive thinning from west to east in the CAOB, which may be caused by lithosphere-asthenosphere interaction. We propose that upwelling of the asthenosphere and subsequent mechanical and chemical erosion beneath lithospheric mantle induced by subduction of the Pacific plate might have been responsible for the lithospheric thinning in the eastern CAOB. The lithospheric thinning has proceeded in a dischronous way in the western North China Craton, near the Daxinganling-Taihangshan gravity lineament, but this event did not take place in the corresponding area of the CAOB. The lithospheric thinning shows different styles both spatially and temporally in the two tectonic units.

  9. Petrogenesis and geodynamics of plagiogranites from Central Turkey (Ekecikdağ/Aksaray): new geochemical and isotopic data for generation in an arc basin system within the northern branch of Neotethys

    NASA Astrophysics Data System (ADS)

    Köksal, Serhat; Toksoy-Köksal, Fatma; Göncüoglu, M. Cemal

    2016-09-01

    In the Late Cretaceous, throughout the closure of the Neotethys Ocean, ophiolitic rocks from the İzmir-Ankara-Erzincan ocean branch were overthrusted the northern margin of the Tauride-Anatolide Platform. The ophiolitic rocks in the Ekecikdaǧ (Aksaray/Central Turkey) region typify the oceanic crust of the İzmir-Ankara-Erzincan branch of Neotethys. The gabbros in the area are cut by copious plagiogranite dykes, and both rock units are intruded by mafic dykes. The plagiogranites are leucocratic, fine- to medium-grained calc-alkaline rocks characterized mainly by plagioclase and quartz, with minor amounts of biotite, hornblende and clinopyroxene, and accessory phases of zircon, titanite, apatite and opaque minerals. They are tonalite and trondhjemite in composition with high SiO2 (69.9-75.9 wt%) and exceptionally low K2O (<0.5 wt%) contents. The plagiogranites in common with gabbros and mafic dykes show high large-ion lithophile elements/high-field strength element ratios with depletion in Nb, Ti and light rare-earth elements with respect to N-MORB. The plagiogranites together with gabbros and mafic dykes show low initial 87Sr/86Sr ratios (0.70419-0.70647), high ƐNd(T) (6.0-7.5) values with 206Pb/204Pb (18.199-18.581), 207Pb/204Pb (15.571-15.639) and 208Pb/204Pb (38.292-38.605) ratios indicating a depleted mantle source modified with a subduction component. They show similar isotopic characteristics to the other supra-subduction zone (SSZ) ophiolites in the Eastern Mediterranean to East Anatolian-Lesser Caucasus and Iran regions. It is suggested that the Ekecikdaǧ plagiogranite was generated in a short time interval from a depleted mantle source in a SSZ/fore-arc basin setting, and its nature was further modified by a subduction component during intra-oceanic subduction.

  10. Mesozoic igneous intrusions in New England and Quebec: Implications from lead (Pb) isotopes on petrogenesis and mantle sources (Ascutney Mountain, Vermont; Mont Saint Hilaire, Quebec; Pliny Complex, New Hampshire)

    SciTech Connect

    Schucker, D.E.

    1992-01-01

    Lead isotopes are used to study Mesozoic intrusions from New England and Quebec, specifically the igneous complexes of Ascutney Mountain (Vermont), Mont Saint Hilaire (Quebec), and Pliny (New Hampshire). The main objectives are to address the: (1) petrogenesis of specific complexes using Pb isotopes along with previous results; and (2) sources of parental magmas in the context of a possible plume source for the Cretaceous intrusions and New England Seamounts. Analytical procedures for Pb and U are also described in detail. For each of the three complexes, significant variation in apparent initial [sup 208]Pb/[sup 204]Pb, [sup 207]Pb/[sup 204]Pb, and [sup 206]Pb/[sup 204]Pb ratios are observed. These variations reflect crustal contamination and local country rocks are isotopically suitable contaminants. Contamination lowers the Pb isotopic ratios of the modified magmas. The Pb ratios of the parental magmas are constrained by defining trends resulting from crustal contamination. At the Ascutney complex, granites appear to be uniform at the time of formation based on feldspar results. Granite whole rocks exhibit open system U-Pb behavior which is attributed to significant recent U loss (of up to 38%). Both local schists and gneisses are important contaminants with generally <25% contamination. Significant isotopic variations are apparent at Mont Saint Hilaire where rock-feldspar variations are apparently not in isotopic equilibrium. Feldspars reflect magmatic values and indicate crustal contamination of a parental magma for the Hilaire complex. A limited data set for the Pliny complex suggests a parental magma. The Pb results support a common mantle source for the Cretaceous continental intrusions (Ascutney and Mont Saint Hilaire) and the New England Seamounts. They imply magma from a sublithospheric mantle-plume, and that magmas ascended with little or no lithospheric interaction. The magma source for the Jurassic Pliny complex appears to be different.

  11. Sr-Nd-Pb-Hf isotope systematics of the Hugo Dummett Cu-Au porphyry deposit (Oyu Tolgoi, Mongolia)

    NASA Astrophysics Data System (ADS)

    Dolgopolova, A.; Seltmann, R.; Armstrong, R.; Belousova, E.; Pankhurst, R. J.; Kavalieris, I.

    2013-04-01

    Major and trace element geochemistry including Sr-Nd-Pb-Hf isotopic data are presented for a representative sample suite of Late Devonian to Early Carboniferous plutonic and volcanic rocks from the Hugo Dummett deposit of the giant Oyu Tolgoi porphyry Cu-Au district in South Gobi, Mongolia. Sr and Nd isotopes (whole-rock) show restricted ranges of initial compositions, with positive ɛNdt mainly between + 3.4 and + 7.4 and (87Sr/86Sr)t predominantly between 0.7037 and 0.7045 reflecting magma generation from a relatively uniform juvenile lithophile-element depleted source. Previously dated zircons from the plutonic rocks exhibit a sample-averaged range of ɛHft values of + 11.6 to + 14.5. Depleted-mantle model ages of 420-830 (Nd) and 320-730 Ma (zircon Hf) limit the involvement of pre-Neoproterozoic crust in the petrogenesis of the intermediate to felsic calc-alkaline magmas to, at most, a minor role. Pb isotopes (whole-rock) show a narrow range of unradiogenic initial compositions: 206Pb/204Pb 17.40-17.94, 207Pb/204Pb 15.43-15.49 and 208Pb/204Pb 37.25-37.64, in agreement with Sr-Nd-Hf isotopes indicating the dominance of a mantle component. All four isotopic systems suggest that the magmas from which the large Oyu Tolgoi porphyry system was generated originated predominantly from juvenile material within the subduction-related setting of the Gurvansayhan terrane.

  12. Early Cretaceous (ca. 100 Ma) magmatism in the southern Qiangtang subterrane, central Tibet: Product of slab break-off?

    NASA Astrophysics Data System (ADS)

    Li, Yalin; He, Haiyang; Wang, Chengshan; Wei, Yushuai; Chen, Xi; He, Juan; Ning, Zijie; Zhou, Aorigele

    2016-09-01

    The lack of Early Cretaceous magmatic records with high-quality geochemical data in the southern Qiangtang subterrane has inhibited a complete understanding of the magmatic processes and geological evolution of central Tibet. In this study, we present zircon U-Pb ages, whole-rock geochemistry, and Sr-Nd-Pb and zircon Hf isotopic data for the newly discovered Moku pluton in the southern Qiangtang subterrane. Zircon U-Pb dating reveals that the Moku granites were emplaced in the Early Cretaceous (ca. 100 Ma) and are coeval with the hosted dioritic enclaves. The granites are slightly peraluminous and high-K calc-alkaline I-type granites and characterized by initial (87Sr/86Sr)i ratios of 0.70605-0.70658, negative ɛ Nd(t) values (-4.44 to -3.35), and Nd isotopic model ages of 1.19-1.29 Ga. The granites have a wide range of zircon ɛ Hf(t) values (-24.4 to 2.6) and concordant ratios of (206Pb/204Pb)t = 18.645-18.711, (207Pb/204Pb)t = 15.656-15.666, and (208Pb/204Pb)t = 38.751-38.836. The coeval dioritic enclaves are medium- to high-K calc-alkaline rocks with zircon ɛ Hf(t) values of -13.3 to +3.6. The geochemical signatures of the host granites and coeval dioritic enclaves indicate that the Moku pluton was most likely generated by partial melting of the ancient lower crust with contributions from mantle-derived melts. Our new data, together with other recently published data, indicate that the ca. 100 Ma magmatic rocks were derived from anatexis of the Qiangtang lower crust that mixed with upwelling asthenosphere materials in response to the slab break-off of the northward subduction of the Bangong-Nujiang oceanic lithosphere.

  13. Siliciclastic Ordovician to Silurian units of the Argentine Precordillera: Constraints on provenance and tectonic setting in the proto-Andean margin of Gondwana

    NASA Astrophysics Data System (ADS)

    Abre, P.; Cingolani, C. A.; Cairncross, B.; Chemale, F.

    2012-12-01

    A combination of petrography, geochemistry, Sm-Nd, Pb-Pb and U-Pb detrital zircon dating provide constraints to the provenance of Middle Ordovician to Early Silurian clastic sequences of the Precordillera s.s. as a part of the Cuyania terrane in western-central Argentina. The uniformity shown by the provenance proxies indicate that there were no important changes in the provenance within these units. A dominant upper crustal component is evident as well as a subordinate mafic input. Nd isotopes indicate ɛNd of -5.4, ƒSm/Nd -0.34 and TDM 1.57 Ga in average for all the units studied. Pb-isotope ratios display average values for 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb of 19.37, 15.86 and 39.43 respectively. Detrital zircon dating further constraints the input as being dominantly of Mesoproterozoic age (51-83%), but with contributions from Neoproterozoic-Lower Cambrian (9-31%), Middle Cambrian to Ordovician grains (recorded up to 7%), and Palaeoproterozoic (2-7%) sources. The combination of the different provenance approaches applied indicates that the Mesoproterozoic Cuyania terrane basement, and partially the Pampia terrane were the main sources. The new information provided for the Ordovician to Silurian clastic sequences permitted enhanced the known geochemical and isotopic dataset to constrain the tectonic evolution of the Cuyania terrane. The interpretation of the obtained data supports that the terrane accretion to the proto-Andean margin of Gondwana probably occurred during Middle to early Upper Ordovician.

  14. Dissolved lead in the deep Southeast Pacific Ocean: results of the 2013 US GEOTRACES cruise

    NASA Astrophysics Data System (ADS)

    Boyle, E. A.; Lee, J. M.; Zhang, J.; Echegoyen, Y.

    2014-12-01

    Lead (Pb) in the modern ocean is dominated by anthropogenic Pb, which has been evidenced by highly elevated seawater Pb concentrations and Pb stable isotope ratios (204Pb, 206Pb, 207Pb, and 208Pb) altered from pre-anthropogenic values. A number of studies have shown the human impact on oceanic Pb in many parts of the world ocean, but little Pb data has been available for the Southeast Pacific Ocean. In this presentation, we will show the dissolved Pb (<0.2µm) results from the US GEOTRACES cruise in October - December 2013, which sailed from Manta, Ecuador, to Tahiti along around 12 degrees south. Dissolved Pb concentrations from all 36 surface stations and deep (>1000m) Pb profiles from 18 stations will be presented, and the results will be also compared to our unpublished data from the BiG RAPA cruise in 2010, whose cruise track from Arica, Peru, to Easter Island is slightly south of the US GEOTRACES cruise. The BiG RAPA data showed that dissolved Pb concentrations of the southeast Pacific Ocean are relatively low, varying in the range of 8-20 pmol/kg at the surface with a slight maximum (14-22 pmol/kg) at around 400m depth, and 2-10 pmol/kg in deep waters below 1000m depth. The Pb concentrations were found to be higher at a marginal station off Peru, reaching 45 pmol/kg at the surface and 65 pmol/kg in the subsurface maximum at 150m depth, and varying between 17 and 23 pmol/kg in deep waters. Our dataset, along with the results from the BiG RAPA cruise, will provide the first overview on the dissolved Pb distribution of the southeast Pacific Ocean, which will further our understanding on the human impact on the global ocean.

  15. Impact of Dust from Ore Processing Facilities on Rain Water Collection Tanks in a Tropical Environment—The Obvious Source “Ain’t Necessarily So”

    PubMed Central

    Gulson, Brian; Korsch, Michael; Bradshaw, Anthony

    2016-01-01

    Concerns have been expressed that dust from the minerals processing facilities at Karumba Queensland Australia have resulted in elevated lead (Pb) concentrations in rain water tanks. The ores derived from the Century mine some 304 km from the port. High precision Pb isotopic measurements on environmental samples have been undertaken to evaluate the source of Pb in rainwaters and acid digests from roof wipes and gutter wipes. There does not appear to be any relationship between sample location and the processing facility but samples from the area subject to the prevailing winds show the highest contribution of Century Pb. All gutter wipes (82 to 1270 µg Pb/wipe) have contributions of Century ore ranging from 87% to 96%. The contribution of Century ore to five roof wipes (22 to 88 µg Pb/wipe) ranges from 89% to 97% and in the other two samples there is a mix of Century and Broken Hill Pb. Three of the seven rainwater have contributions of Century ore Pb ranging from 33% to 75%. Two of the other four rainwater samples have the highest water Pb concentrations of 88 and 100 µg/L and their isotopic data show Broken Hill Pb contributions ranging from 77% to 80%. The source of the Broken Hill Pb is probably from the galvanized roofing material and/or brass fittings in the rainwater tanks. The discrimination between various sources is only detectable using high precision 204Pb-based isotopic ratios and not the now common inductively coupled plasma mass spectrometry (ICP-MS ) data presentations of the higher abundance isotopes 208Pb, 207Pb and 206Pb. Isotopic results for the waters demonstrate that apportioning blame where there is an obvious point source may not always be the correct conclusion. Nevertheless the isotopic data for the gutter wipes indicates that there was widespread contamination from the processing facilities throughout the town. PMID:26907319

  16. Geochemistry of A-type granites in the Huangshaping polymetallic deposit (South Hunan, China): Implications for granite evolution and associated mineralization

    NASA Astrophysics Data System (ADS)

    Li, Huan; Watanabe, Koichiro; Yonezu, Kotaro

    2014-07-01

    The Huangshaping granites in Hunan Province, South China were investigated for their geochemical characteristics. Three types of granites have been petrographically identified: quartz porphyry, granophyre, and granite porphyry. Whole rock geochemistry suggests that the Huangshaping granites, especially the granite porphyry, exhibit typical A-type granite characteristics with their enrichment in Si, Rb, U, Th, and Nb and significant depletion in Ba, Sr, Ti, Eu, and P. Based on the Al, Y and Zr contents as well as the REE patterns of the rocks investigated, the quartz porphyry and the granophyre are classified as A1 type alkaline granites whereas the granite porphyry is considered as A2 type aluminous granite. Whole rock and quartz/feldspar O isotope data yields a wide range of δ18OSMOW values (11.09-26.32‰). The granites are characterized by high radiogenic Pb isotopic composition. The present-day whole rock Pb isotopic ratios are 206Pb/204Pb = 18.706-19.155, 207Pb/204Pb = 15.616-15.711 and 208Pb/204Pb = 38.734-39.296. Combining the O-Pb isotope compositions with major, trace and REE geochemistry and regional geology characteristics, the Huangshaping granites were determined to resemble within-plate granites that were mainly derived from a felsic infracrustal source related to continental extension. The magma source of the quartz porphyry and the granophyre may have been generated from deeper depths, and then ascended rapidly with limited water content and low oxygen fugacity, which contributed to Cu, Pb and Zn mineralization. On the other hand, the magma that generated the granite porphyry may have ascended relatively slower and experienced pronounced crystal fractionation, upper-crustal basement rock contamination (assimilation) and wall-rock interaction, producing the Sn- and W-rich granite porphyry. This study reveals the crustal extension process and associated magmatic-metallogenic activities during 180-150 Ma in South Hunan.

  17. Trace Metals, Rare Earths, Carbon and Pb Isotopes as Proxies of Environmental Catastrophe at the Permian - Triassic Boundary in Spiti Himalayas, India

    NASA Astrophysics Data System (ADS)

    Ghosh, N.; Basu, A. R.; Garzione, C. N.; Ghatak, A.; Bhargava, O. N.; Shukla, U. K.; Ahluwalia, A. D.

    2015-12-01

    Himalayan sediments from Spiti Valley, India preserve geochemical signatures of the Permian - Triassic (P-Tr) mass extinction in the Neo-Tethys Ocean. We integrate new sedimentological and fossil record with high-resolution geochemical-isotopic data from Spiti that reveals an ecological catastrophe of global proportions. Trace elements of U, Th, Nb, Ta, Zr, Hf, the rare earths (REE) and carbon, oxygen and lead isotopes measured across the P-Tr boundary in Spiti are used as proxies for evaluating abrupt changes in this continental shelf environment. δ13Corg excursions of 2.4‰ and 3.1‰ in Atargu and Guling P-Tr sections in Spiti Valley are associated with an abrupt fall of biological productivity while δ13Ccarb and δ18Ocarb record of these sediments shows effects of diagenesis. Here, the P-Tr boundary is compositionally distinct from the underlying Late Permian gray shales, as a partly gypsiferous ferruginous layer that allows additional geochemical-isotopic investigation of sedimentary sources. Conspicuous Ce - Eu anomalies in the light REE-enriched Late Permian shales reflect the source composition of the adjacent Panjal Trap basalts of Kashmir. An abrupt change of this source to continental crust is revealed by Nb - Ta and Zr - Hf anomalies at the P-Tr ferruginous layer and continuing through the overlying Early Triassic carbonate rocks. Pb concentration and isotope ratios of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb identify changes in the sedimentary element flux, distinguishing the Late Permian shales from the distinct siliciclastic continental crustal signature in the Early Triassic carbonates. These geochemical-isotopic constraints on the sedimentary geochemistry of one of the most critical transitions in geological record establish the utility of multi-proxy datasets for paleoenvironmental reconstructions.

  18. The Permian Dongfanghong island-arc gabbro of the Wandashan Orogen, NE China: Implications for Paleo-Pacific subduction

    NASA Astrophysics Data System (ADS)

    Sun, Ming-Dao; Xu, Yi-Gang; Wilde, Simon A.; Chen, Han-Lin; Yang, Shu-Feng

    2015-09-01

    The Dongfanghong hornblende gabbro is located in the western part of the Wandashan Orogen and to the east of the Jiamusi Block in NE China. It was emplaced into Early Paleozoic oceanic crust (i.e. Dongfanghong ophiolite) at ~ 275 Ma and both later collided with the eastern margin of the Jiamusi Block. The Dongfanghong gabbro is sub-alkaline with high Na2O contents and is characterized by enrichment in light rare earth elements (LREE), large ion lithosphile elements (LILE), Sr, Eu, and Ba, and depletion in high field strength elements (HFSE). The enriched isotopic signatures (87Sr/86Sri = ~ 0.7065, εNd(t) = ~- 0.5, 208Pb/204Pbi = ~ 38.05, 207Pb/204Pbi = ~ 15.56, 206Pb/204Pbi = ~ 18.20 and zircon εHf(t) = ~+ 5.8) indicate an enriched mantle (EM2) source, with some addition of continental material. It has arc geochemical affinities similar to Permian arc igneous rocks in the eastern margin of the Jiamusi Block, the Yakuno Ophiolite in SW Japan, arc rocks along the western margin of the North America Craton, and also the Gympie Group in eastern Australia. All these features, together with information from tectonic discrimination diagrams, suggest that the Dongfanghong gabbro formed in an immature island arc. The spatial configuration of ~ 290 Ma immature continental arc rocks in the eastern part of the Jiamusi Block and the ~ 275 Ma immature island arc Dongfanghong gabbro in the Wandashan Orogen to the east is best explained by eastward arc retreat and slab roll-back of the Paleo-Pacific Plate. This model is also supported by the Carboniferous-Permian stratigraphic transition in the Jiamusi Block from oceanic carbonate rocks to coal-bearing terrestrial clastic rocks and andesites. We thus suggest that both Paleo-Pacific subduction and roll-back occurred in the Early Permian along the eastern margin of Asia.

  19. Lead isotopic studies of the Samail ophiolite, Oman

    SciTech Connect

    Chen, J.H.; Pallister, J.S.

    1981-04-10

    The isotopic composition of Pb and the concentrations of U, Th, and Pb have been determined for samples from various lithologic units and massive sulfides of the Samail ophiolite. The observed /sup 206/Pb//sup 204/Pb ratios range from 17.90 to 19.06, /sup 207/Pb//sup 204/Pb ratios from 15.43 to 15.63, and /sup 208/Pb//sup 204/Pb from 37.66 to 38.78. In Pb isotopic evolution diagrams, the initial Pb isotopic compositions of most of the samples from the Samail ophiolite plot within the field of oceanic basalt, clearly distinct from island arc data, and define some of the least radiogenic Pb observed from oceanic rocks. Lead data from the Samail are compatible with a model involving magma generation from an oceanic mantle source and formation of the ophiolite at an oceanic spreading center. U--Th--Pb isotopic systematics demonstrate that vertical heterogeneity in the oceanic crust can be created through differential concentration of U, Th, and Pb during crystal fractionation and alteration at, or near, the spreading ridge. Calcite form amygdules in the ophiolite basalt has similar Pb isotopic composition to the igneous rocks, suggesting precipitation of the calcite from seawater which contained Pb derived mostly from the oceanic crust. Lead isotopic data on Fe--Cu sulfides are also similar to the results from the igneous suite suggesting that the source of the sulfides is predominently from the oceanic crust. Lead data from serpentinized peridotite and a galena sample from below the ophiolite suggest that part of the serpentinization process and the formation of galena could involve addition of radiogenic Pb from either a continental source or from oceanic sediments.

  20. Expanded Geochemical Analysis of the Eocene Crescent Formation, Olympic Peninsula, Washington

    NASA Astrophysics Data System (ADS)

    Haileab, B.; Denny, A.; Harrison, B. K.

    2012-12-01

    The Coast Range Volcanic Province (Siletzia) of Washington and Oregon formed adjacent to western North America in the early Eocene, and consists of an estimated 250,000 km3 of predominantly tholeiitic flows. In the Crescent Formation, which is locally divided into a submarine lower member and a subaerial upper member, this basaltic flow sequence reaches stratigraphic thicknesses of up to 16 km. A consensus has yet to be reached on the origin of this Large Igneous Province (LIP); proposed mechanisms include slab windows, margin-parallel rifting, and the action of the Yellowstone hotspot. Outcrop evidence for shallow-water depositional environments in the Lower Crescent argues against the member's origin as an abducted portion of oceanic crust, as has also been proposed, and further supports the widely held view that the Upper and Lower Crescent members together represent a nearly continuous eruptive sequence. Rare Earth Element plots for both members display three distinct trends that suggest high and low degrees of both mantle partial melting and fractional crystallization. We also present here what we believe are the first isotopic values for the Lower Crescent (0.512941<143Nd/144Nd<0.512997, 0.703287<87Sr/86Sr<0.703678, 18.907<206Pb/204Pb<19.240, 15.599<207Pb/204Pb<15.661, 38.521<208Pb/204Pb<39.034), which are similar to previous isotopic data collected for the Upper Crescent and suggest a plume component in the mantle source for these rocks.

  1. The origin of lead in the organic horizon of tundra soils: atmospheric deposition, plant translocation from the mineral soil or soil mineral mixing?

    PubMed

    Klaminder, Jonatan; Farmer, John G; MacKenzie, Angus B

    2011-09-15

    Knowledge of the anthropogenic contribution to lead (Pb) concentrations in surface soils in high latitude ecosystems is central to our understanding of the extent of atmospheric Pb contamination. In this study, we reconstructed fallout of Pb at a remote sub-arctic region by using two ombrotrophic peat cores and assessed the extent to which this airborne Pb is able to explain the isotopic composition ((206)Pb/(207)Pb ratio) in the O-horizon of tundra soils. In the peat cores, long-range atmospheric fallout appeared to be the main source of Pb as indicated by temporal trends that followed the known European pollution history, i.e. accelerated fallout at the onset of industrialization and peak fallout around the 1960s-70s. The Pb isotopic composition of the O-horizon of podzolic tundra soil ((206)Pb/(207)Pb=1.170 ± 0.002; mean ± SD) overlapped with that of the peat ((206)Pb/(207)Pb=1.16 ± 0.01) representing a proxy for atmospheric aerosols, but was clearly different from that of the parent soil material ((206)Pb/(207)Pb=1.22-1.30). This finding indicated that long-range fallout of atmospheric Pb is the main driver of Pb accumulation in podzolic tundra soil. In O-horizons of tundra soil weakly affected by cryoturbation (cryosols) however, the input of Pb from the underlying mineral soil increased as indicated by (206)Pb/(207)Pb ratios of up to 1.20, a value closer to that of local soil minerals. Nevertheless, atmospheric Pb appeared to be the dominant source in this soil compartment. We conclude that Pb concentrations in the O-horizon of studied tundra soils - despite being much lower than in boreal soils and representative for one of the least exposed sites to atmospheric Pb contaminants in Europe - are mainly controlled by atmospheric inputs from distant anthropogenic sources.

  2. Radiogenic Isotopes in Weathering and Hydrology

    NASA Astrophysics Data System (ADS)

    Blum, J. D.; Erel, Y.

    2003-12-01

    cycling of calcium. The decay of 235U to 207Pb, 238U to 206Pb, and 232Th to 208Pb have half-lives of 0.704 Gyr, 4.47 Gyr, and 14.0 Gyr, respectively, and result in variations in the 207Pb/204Pb, 206Pb/204Pb, and 208Pb/204Pb ratios (e.g., Blum, 1995). Uranium-234 has a half-life of 0.25 Myr and the ratio 234U/238U approaches a constant secular equilibrium value in rocks and minerals if undisturbed for ˜1 Myr. Differences in this ratio are often observed in solutions following rock-water interaction and have been used in studies of weathering and hydrology. Uranium and thorium tend to be highly concentrated in the trace accessory minerals such as zircon, monazite, apatite, and sphene, which therefore develop high 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios. Once released into the hydrosphere, lead retains its isotopic composition without significant geochemical or biological fractionation and tends to generally follow the chemistry of iron in soils and aqueous systems (Erel and Morgan, 1992). The use of the U-Th disequilibrium series as a dating tool falls outside the scope of this chapter and is reviewed in Chapters 6.14 and 6.17 as well as Chapter 3.15. The decay of 147Sm to 143Nd, 176Lu to 176Hf, and 187Re to 187Os have half-lives of 106 Gyr, 35.7 Gyr, and 42.3 Gyr, respectively, and result in natural variability in the 144Nd/143Nd, 176Hf/177Hf, and 187Os/188Os ratios (e.g., Blum, 1995). Neodymium is a rare earth element (REE), hafnium is a transition metal with chemical similarities to zirconium, and osmium is a platinum group element. The geochemical behaviors of these elements in the hydrosphere are largely determined by these chemical affinities.

  3. Childhood lead poisoning from the smelter in Torreón, México.

    PubMed

    Soto-Jiménez, Martin F; Flegal, Arthur R

    2011-05-01

    Lead concentrations and isotopic compositions in blood samples of 34 children (ages 2-17 years) living within a 113 km(2) area of a silver-zinc-lead smelter plant in Torreón, México were compared to those of associated environmental samples (soil, aerosols, and outdoor and indoor dust) to identify the principal source(s) of environmental and human lead contamination in the area. Lead concentrations of soil and outdoor dust ranged 130-12,050 and 150-14,365 μg g(-1), respectively. Concentrations were greatest near the smelter, with the highest levels corresponding with the prevailing wind direction, and orders of magnitude above background concentrations of 7.3-33.3 μg g(-1). Atmospheric lead depositions in the city varied between 130 and 1350 μg m(-2) d(-1), again with highest rates <1 km from the smelter. Blood lead (PbB) concentrations (11.0±5.3 μg dl(-1)) levels in the children ranged 5.0-25.8 μg dl(-1), which is 3-14 times higher than the current average (1.9 μg dl(-1)) of children (ages 1-5 years) in the US. Lead isotopic ratios ((206)Pb/(207)Pb, (208)Pb/(207)Pb) of the urban dust and soil (1.200±0.009, 2.467±0.003), aerosols (1.200±0.002, 2.466±0.002), and PbB (1.199±0.001, 2.468±0.002) were indistinguishable from each other, as well as those of the lead ores processed at the smelter (1.199±0.007, 2.473±0.007). Consequently, an elevated PbB concentrations of the children in Torreón, as well as in their environment, are still dominated by industrial emissions from the smelter located within the city, in spite of new controls on atmospheric releases from the facility. PMID:21329917

  4. Environmental arsenic, cadmium and lead dust emissions from metal mine operations: Implications for environmental management, monitoring and human health

    SciTech Connect

    Taylor, Mark Patrick Mould, Simon Anthony; Kristensen, Louise Jane; Rouillon, Marek

    2014-11-15

    Although blood lead values in children are predominantly falling globally, there are locations where lead exposure remains a persistent problem. One such location is Broken Hill, Australia, where the percentage of blood lead values >10 μg/dL in children aged 1–4 years has risen from 12.6% (2010), to 13% (2011) to 21% (2012). The purpose of this study was to determine the extent of metal contamination in places accessible to children. This study examines contemporary exposure risks from arsenic, cadmium, lead, silver and zinc in surface soil and dust, and in pre- and post-play hand wipes at six playgrounds across Broken Hill over a 5-day period in September 2013. Soil lead (mean 2,450 mg/kg) and zinc (mean 3,710 mg/kg) were the most elevated metals in playgrounds. Surface dust lead concentrations were consistently elevated (mean 27,500 μg/m{sup 2}) with the highest lead in surface dust (59,900 μg/m{sup 2}) and post-play hand wipes (60,900 μg/m{sup 2}) recorded close to existing mining operations. Surface and post-play hand wipe dust values exceeded national guidelines for lead and international benchmarks for arsenic, cadmium and lead. Lead isotopic compositions ({sup 206}Pb/{sup 207}Pb, {sup 208}Pb/{sup 207}Pb) of surface dust wipes from the playgrounds revealed the source of lead contamination to be indistinct from the local Broken Hill ore body. The data suggest frequent, cumulative and ongoing mine-derived dust metal contamination poses a serious risk of harm to children. - Highlights: 1.Playground soils and surface dust in a mining town have high metal concentrations. 2.Elevated levels of As, Cd, Pb and Zn dust are found on playground users′ hands. 3.Pb isotope analysis shows that the source of playground dust is ore body Pb. 4.Surface mine operations must be contained to reduce childhood lead exposure risks. 5.Mine environmental licences need to set trigger values for As, Cd, Pb and Zn dust.

  5. Childhood lead poisoning from the smelter in Torreón, México.

    PubMed

    Soto-Jiménez, Martin F; Flegal, Arthur R

    2011-05-01

    Lead concentrations and isotopic compositions in blood samples of 34 children (ages 2-17 years) living within a 113 km(2) area of a silver-zinc-lead smelter plant in Torreón, México were compared to those of associated environmental samples (soil, aerosols, and outdoor and indoor dust) to identify the principal source(s) of environmental and human lead contamination in the area. Lead concentrations of soil and outdoor dust ranged 130-12,050 and 150-14,365 μg g(-1), respectively. Concentrations were greatest near the smelter, with the highest levels corresponding with the prevailing wind direction, and orders of magnitude above background concentrations of 7.3-33.3 μg g(-1). Atmospheric lead depositions in the city varied between 130 and 1350 μg m(-2) d(-1), again with highest rates <1 km from the smelter. Blood lead (PbB) concentrations (11.0±5.3 μg dl(-1)) levels in the children ranged 5.0-25.8 μg dl(-1), which is 3-14 times higher than the current average (1.9 μg dl(-1)) of children (ages 1-5 years) in the US. Lead isotopic ratios ((206)Pb/(207)Pb, (208)Pb/(207)Pb) of the urban dust and soil (1.200±0.009, 2.467±0.003), aerosols (1.200±0.002, 2.466±0.002), and PbB (1.199±0.001, 2.468±0.002) were indistinguishable from each other, as well as those of the lead ores processed at the smelter (1.199±0.007, 2.473±0.007). Consequently, an elevated PbB concentrations of the children in Torreón, as well as in their environment, are still dominated by industrial emissions from the smelter located within the city, in spite of new controls on atmospheric releases from the facility.

  6. Childhood lead poisoning from the smelter in Torreon, Mexico

    SciTech Connect

    Soto-Jimenez, Martin F.; Flegal, Arthur R.

    2011-05-15

    Lead concentrations and isotopic compositions in blood samples of 34 children (ages 2-17 years) living within a 113 km{sup 2} area of a silver-zinc-lead smelter plant in Torreon, Mexico were compared to those of associated environmental samples (soil, aerosols, and outdoor and indoor dust) to identify the principal source(s) of environmental and human lead contamination in the area. Lead concentrations of soil and outdoor dust ranged 130-12,050 and 150-14,365 {mu}g g{sup -1}, respectively. Concentrations were greatest near the smelter, with the highest levels corresponding with the prevailing wind direction, and orders of magnitude above background concentrations of 7.3-33.3 {mu}g g{sup -1}. Atmospheric lead depositions in the city varied between 130 and 1350 {mu}g m{sup -2} d{sup -1}, again with highest rates <1 km from the smelter. Blood lead (PbB) concentrations (11.0{+-}5.3 {mu}g dl{sup -1}) levels in the children ranged 5.0-25.8 {mu}g dl{sup -1}, which is 3-14 times higher than the current average (1.9 {mu}g dl{sup -1}) of children (ages 1-5 years) in the US. Lead isotopic ratios ({sup 206}Pb/{sup 207}Pb, {sup 208}Pb/{sup 207}Pb) of the urban dust and soil (1.200{+-}0.009, 2.467{+-}0.003), aerosols (1.200{+-}0.002, 2.466{+-}0.002), and PbB (1.199{+-}0.001, 2.468{+-}0.002) were indistinguishable from each other, as well as those of the lead ores processed at the smelter (1.199{+-}0.007, 2.473{+-}0.007). Consequently, an elevated PbB concentrations of the children in Torreon, as well as in their environment, are still dominated by industrial emissions from the smelter located within the city, in spite of new controls on atmospheric releases from the facility. - Highlights: {yields} Pb contents in environmental samples evidenced chronic Pb pollution in Torreon. {yields} Pb stable isotopes evidenced contemporary emissions from the Ag-Cod-Pb-Zn smelter. {yields} Pb urban dust and soil account for most of the childhood lead poisoning in Torreon.{yields} Levels of

  7. A lead isotopic study of the Stillwater Complex, Montana: constraints on crustal contamination and source regions

    USGS Publications Warehouse

    Wooden, J.L.; Czamanske, G.K.; Zientek, M.L.

    1991-01-01

    Analyses of the Pb isotopic compositions of plagioclase from 23 samples covering the stratigraphic thickness of the Stillwater Complex indicate a narrow range of apparent initial isotopic compositions (206Pb/ 204Pb=13.95; 207Pb/204Pb=14.95-15.01; 208Pb/204Pb=33.6). The uniformity of our data is in contrast to, but not necessarily contradictory to, other recent investigations which give indications that the complex formed by repeated injection of magmas with at least two distinct compositions that were presumably derived from different source regions. Samples from the Basal series of the complex have consistently higher 207Pb/204Pb ratios, suggesting either minor contamination from adjacent country rocks or a slight distinction between parental magmas. Apparent initial Pb isotopic compositions of the complex are very radiogenic compared to Late Archean model-mantle values, but are nearly identical to initial Pb isotopic compositions found for the the adjacent, slightly older (2.73-2.79 Ga), Late Archean crustal suite in the Beartooth Mountains. Contamination of magmas parental to the Stillwater Complex by the Late Archean crustal suite is rejected for two reasons: (1) Th and U concentrations in Stillwater rocks and plagioclase are very low (about 0.08 and 0.02 ppm respectively), yet Th/U ratios are uniform at about 4, in contrast to the highly variable (2-26) but often high Th/U ratios found for the Late Archean crustal complex; (2) it seems improbable that any contamination process would have adjusted the isotopic compositions of the diverse magmas entering the Stillwater chamber to near-identical values. The preferred hypothesis to explain the Pb isotopic data for the Stillwater Complex and the associated Late Archean crustal suite involves a major Late Archean crust-forming event that resulted in a compositionally complex crust/mantle system with relatively homogeneous and unusual Pb isotopic compositions. The parental magmas of the Stillwater Complex were

  8. Shifts in alpine lakes' ecosystems in Japan driven by increasing Asian dusts

    NASA Astrophysics Data System (ADS)

    Tsugeki, N. K.; Tani, Y.; Ueda, S.; Agusa, T.; Toyoda, K.; Kuwae, M.; Oda, H.; Tanabe, S.; Urabe, J.

    2011-12-01

    Recently in East Asia the amount of fossil fuel combustion have increased with economic growth. It has caused a problem of trans-boundary air pollution in the whole of eastern Asia. Furthermore, Asian dust storms contribute episodically to the global aerosol load. However, the effects of increased Asian dusts on aquatic ecosystems are not well understood. If biologically important nutrients such as nitrogen (N) and phosphorus (P) are transported via air dust, the atmospheric deposition of the dust may have serious impacts on recipient aquatic ecosystems because the biological production is limited by these nutrient elements. A previous report using sedimentary records has evaluated that atmospheric P inputs to the alpine lakes in the United States increased fivefold following the increased western settlement to this country during the nineteenth century. Since P is the most deficient nutrient for production in many lakes increase in P loading through atmospheric deposition of anthropogenically-derived dust might greatly affect the lake ecosystems. We examined fossil pigments and zooplankton remains from Pb-dated sediments taken from a high mountain lake of Hourai-Numa, located in the Towada-Hachimantai National Park of Japan, to uncover historical changes in the phyto- and zooplankton community over the past 100 years. Simultaneously, we measured the biogeochemical variables of TOC, TN, TP, δ13C, δ15N, and 206Pb/207Pb, 208Pb/207Pb in the sediments to identify environmental factors causing such changes. As a result, despite little anthropogenic activities in the watersheds, alpine lakes in Japan Islands increased algal and herbivore plankton biomasses by 3-6 folds for recent years depending on terrestrial the surrounded vegetations and landscape conditions. Biological and biogeochemical proxies recorded in the lake sediments indicate that this eutrophication occurred after the 1990s when P deposition increased due to atmospheric loading transported from Asian

  9. Historical lead isotope record of a sediment core from the Derwent River (Tasmania, Australia): a multiple source environment.

    PubMed

    Townsend, Ashley T; Seen, Andrew J

    2012-05-01

    A 105 cm sediment core from the Derwent River (Tasmania, Australia) was collected in 2004 and was characterised considering both physical (loss on ignition at 550 °C and grain size) and chemical (Fe, Cu, Zn, Cd and Pb concentrations, Pb isotope ratios and (210)Pb dating) properties. The core was analysed to (i) investigate the historical profiles of some important elements associated with the Risdon zinc refinery adjacent to the Derwent River, (ii) determine Pb isotopic signatures of sediment samples, and (iii) assess the veracity of Pb isotope ratios as indicators of contaminant Pb input. Extractable metal concentrations were (all values as mgkg(-1), non-normalised for grain size) Fe: 20,000-35,000, Zn: 42-4500, Pb: 5-1090, Cu: 13-141, and Cd: 1-31; with a close correlation between Cu, Zn, Cd and Pb. Metal enrichment factors (normalised to Al) were Pb: 0.9-144, Zn: 0.8-93, Cd: 0.8-30, Cu: 0.8-8.9 and Fe: 0.9-1.3, confirming anthropogenic contributions of Cu, Zn, Pb and Cd to the sediments. The onset of metal contamination above background levels occurred at a depth between 43 and 49 cm, with maximum concentrations noted near 20 cm for Cu, Zn, Cd and Pb. Lead isotope ratios were determined in sediments using sector field ICP-MS, and were found to be 36.5-38.8, 16.5-18.7 and 1.07-1.20 for (208)Pb/(204)Pb, (206)Pb/(204)Pb and (206)Pb/(207)Pb ratios, respectively. Major Australian ores processed at the refinery over the previous ~90 years include those from Broken Hill, Rosebery, Mt Isa, Elura, Hellyer and Century deposits. Anthropogenic impact by Pb with Broken Hill type isotopic ratio was initially evident in the core at 43-49 cm. The introduction of Rosebery and Elura ores to the refinery was also clearly noted. Pb isotope ratios further highlight that the Derwent River has been exposed to a greater impact by anthropogenic Pb in comparison to other major Tasmanian rivers, namely the Huon and Tamar.

  10. N zooming into the Mediterranean outflow fossil moat during the 1.2-1.8 million years period (Early-Pleistocene) - An approach by radiogenic and stable isotopes

    NASA Astrophysics Data System (ADS)

    Lebreiro, Susana M.; Antón, Laura; Reguera, M. Isabel; Fernández, Marta; Conde, Estefanía; Barrado, Ana I.; Yllera, Abel

    2015-12-01

    The fossil Alvarez Cabral erosive Moat contains hemipelagite, contourite and turbidite facies where oceanography changes in the Mediterranean outflow are archived over the 1.2-1.8 Myr time period. Here we used Pb and Sr radiogenic isotopes to trace water masses and sediment source changes, for the first time in twenty glacial-interglacial (G-I) cycles of the Early-Pleistocene interval, and the last Glacial Maximum through Holocene cycle (including the Younger Dryas and Heinrich Stadial-1). A mixing line of Pb isotopes gives reliable low radiogenic 208Pb/204Pb, 206Pb/204Pb, and 206Pb/207Pb typical of Mediterranean Outflow Water (MOW) in one end-member and the signature of high radiogenic isotopes of Atlantic Waters (AW) towards the second end-member. The 87Sr/86Sr isotopes also display two end-members of the mixing line between eolian transport/dust source (0.71) and fluvial transport/weathering source (0.73) previously proposed in the Gulf of Cadiz. Combination of Pb and Sr radiogenic isotopes with O and C stable isotopes of planktonic and benthic foraminifera, and the response of foraminifera benthos over the Early-Pleistocene interval, reveals a direct link between water masses circulation and shifts in G-I. We found a persistent cyclic pattern of MOW circulation and fluvial deposition during glaciations and AW and aeolian influence during interglaciations. On site U1386B/C, the upper-MOW was less ventilated but productive and with high flux of organic flux matter during glacials, while Atlantic Waters were better ventilated, enriched in O, but less productive during interglacials. We infer that shifts in ocean and atmospheric processes in the Gulf of Cadiz were strongly controlled by Earth's obliquity (41 kyr-cycle) and 35°NH insolation during the Early-Pleistocene. We propose a correlation in changes in phase-relationship between precession and obliquity. In general terms, physical properties of fine sediments (glacials) show lower NGR, low reflectance and

  11. Upper and lower crust recycling in the source of CAMP basaltic dykes from southeastern North America

    NASA Astrophysics Data System (ADS)

    Callegaro, Sara; Marzoli, Andrea; Bertrand, Hervé; Chiaradia, Massimo; Reisberg, Laurie; Meyzen, Christine; Bellieni, Giuliano; Weems, Robert E.; Merle, Renaud

    2013-08-01

    The densest dykes swarm of the Central Atlantic magmatic province (CAMP) occur in southeastern North America (SENA) and were intruded between 202 and 195 Ma during Pangea break-up. New combined geochemical data (major and trace elements, Sr-Nd-Pb-Os isotopes) constrain the mantle source of these magmatic bodies and their evolution path. While Sr-Nd isotopic compositions for SENA rocks (87Sr/86Sr200Ma 0.70438-0.70880 and 143Nd/144Nd200Ma 0.51251-0.51204) fall within the low-Ti CAMP field, Pb-Pb isotopes (206Pb/204Pb200Ma 17.46-18.85, 207Pb/204Pb200Ma 15.54-15.65, 208Pb/204Pb200Ma 37.47-38.76) are peculiar to this area of the CAMP and cover a considerable span of compositions, especially in 206Pb/204Pb200Ma. Given the generally unradiogenic Os isotopic compositions (187Os/188Os200Ma 0.127-0.144) observed and the lack of correlation between these and other geochemical markers, crustal contamination during the evolution of SENA dykes must have been limited (less than 10%). Thus the isotopic variation is interpreted to reside primarily within the mantle source. These observations, coupled with typical continental signatures in trace elements (positive anomaly in Pb and negative anomalies in Ti and Nb), require another means of conveying a continental flavor to these magmas, which is here hypothesized to be the shallow recycling within the upper mantle of subducted lower and upper crustal materials. Pseudo-ternary mixing models show that a maximum of 10% recycled crust is enough to explain their trace element patterns as well as their isotopic heterogeneity. Looking at the larger picture of the origin of the CAMP, the thermal contribution of a mantle plume cannot be ruled out due to the relatively high mantle potential temperatures (1430-1480 °C) calculated for high-Fo SENA olivines. Nevertheless, our results suggest that the chemical involvement of a mantle plume is negligible (less than 5%) if either a C- or an EM-flavored plume is considered. Rather, the possibility

  12. A Geochemical and Isotopic Study of the Youngest Lavas from the Islands of Upolu and Savai’i, Samoa

    NASA Astrophysics Data System (ADS)

    Buhler, A.; Pietruszka, A. J.; Hanan, B. B.

    2009-12-01

    We report major and trace element abundances and Hf, Pb, Sr, and Nd isotopic ratios for eight of the youngest rejuvenation stage lavas from the Samoan Islands of Upolu and Savai’i. The extensive and voluminous amount of rejuvenation stage volcanism on the Samoan islands, especially on the islands of Savai’i and Upolu, has made these islands key in the understanding of rejuvenation magmatism. The six lavas from Upolu are basanites, whereas the two lavas from Savai’i are alkali basalts. With the exception of one basanite with 7.4 wt. % MgO, all of the samples are relatively primitive (MgO = 10.5 to 12.2 wt. %) and show little evidence of fractionation beyond olivine control. However, variations in major element abundances at a given MgO value indicate changes in the parental melt composition. This interpretation is confirmed by wide variations in ratios of incompatible trace elements (e.g., Nb/La or Ce/Yb). On a primitive mantle normalized trace element diagram, the lavas have relatively constant, low abundances of heavy rare-earth elements (e.g., Yb) due to the presence of residual garnet in the mantle source region. The ɛNd (-0.3 to +2.9) and ɛHf (+3.7 to +8.0) values, and Pb isotope ratios (e.g., 206Pb/204Pb = 18.57-18.88, Δ207Pb/204Pb = 3.3-11.4, and Δ208Pb/204Pb = 59.4-76.3) vary significantly but plot within the range of published data for rejuvenation stage lavas from these islands. On a plot of ɛNd vs. 206Pb/204Pb, the new Upolu and Savai’i analyses make a distinctive positive correlation that overlaps with previous analyses of rejuvenation stage lavas from these islands. Interestingly, this trend is distinct from the ones defined by many of the purported Upolu and Savai’i shield stage lavas. These data will help to better understand the origin of rejuvenation stage magmatism.

  13. Sources of granite magmatism in the Embu Terrane (Ribeira Belt, Brazil): Neoproterozoic crust recycling constrained by elemental and isotope (Sr-Nd-Pb) geochemistry

    NASA Astrophysics Data System (ADS)

    Alves, Adriana; Janasi, Valdecir de Assis; Campos Neto, Mario da Costa

    2016-07-01

    Whole rock elemental and Sr-Nd isotope geochemistry and in situ K-feldspar Pb isotope geochemistry were used to identify the sources involved in the genesis of Neoproterozoic granites from the Embu Terrane, Ribeira Belt, SE Brazil. Granite magmatism spanned over 200 Ma (810-580 Ma), and is dominated by crust-derived relatively low-T (850-750 °C, zircon saturation) biotite granites to biotite-muscovite granites. Two Cryogenian plutons show the least negative εNdt (-8 to -10) and highest mg# (30-40) of the whole set. Their compositions are strongly contrasted, implying distinct sources for the peraluminous (ASI ∼ 1.2) ∼660 Ma Serra do Quebra-Cangalha batholith (metasedimentary rocks from relatively young upper crust with high Rb/Sr and low Th/U) and the metaluminous (ASI = 0.96-1.00) ∼ 630 Ma Santa Catarina Granite. Although not typical, the geochemical signature of these granites may reflect a continental margin arc environment, and they could be products of a prolonged period of oceanic plate consumption started at ∼810 Ma. The predominant Ediacaran (595-580 Ma) plutons have a spread of compositions from biotite granites with SiO2 as low as ∼65% (e.g., Itapeti, Mauá, Sabaúna and Lagoinha granites) to fractionated muscovite granites (Mogi das Cruzes, Santa Branca and Guacuri granites; up to ∼75% SiO2). εNdT are characteristically negative (-12 to -18), with corresponding Nd TDM indicating sources with Paleoproterozoic mean crustal ages (2.0-2.5 Ga). The Guacuri and Santa Branca muscovite granites have the more negative εNdt, highest 87Sr/86Srt (0.714-0.717) and lowest 208Pb/206Pb and 207Pb/206Pb, consistent with an old metasedimentary source with low time-integrated Rb/Sr. However, a positive Nd-Sr isotope correlation is suggested by data from the other granites, and would be consistent with mixing between an older source predominant in the Mauá granite and a younger, high Rb/Sr source that is more abundant in the Lagoinha granite sample. The

  14. Lead isotopes and the sources of the Columbia River Basalt Group

    NASA Astrophysics Data System (ADS)

    Chamberlain, V. E.; Lambert, R. St. J.

    1994-06-01

    A detailed study of Pb-208/Pb-204, Pb-207/Pb-204, and Pb-206/Pb-204 ratios suggests that the number of Pb isotopic reservoirs required for the Columbia River Basalt Group (CRBG) (as currently defined) must be increased from the presently accepted four to at least six. The identities of the six reservoirs are two of mid-ocean ridge basalt (MORB) slightly contaminated with sediment (R1 and R2, R1 being 'Cascades' PB); one a probable plume component (R3); two of unspecified mantle material but probably of R1 type, contaminated with local crustal Pb (R4 and R5); and the sixth a complex enriched reservoir of 2150 Ma age (R6). R1 is an end-member for all CRBG, except the Saddle Mountains Basalts. R2 is a second end-member for the Picture Gorge Basalt and CRBG, except the Saddle Mountains Basalts. R2 is a second end-member for the Picture Gorge Basalt and appears to be unique to it. R3 is the principal source for most of the Wanapum Basalt, as well as for most of the chemically evolved portions of the Grande Ronde Basalt. Volumetric and tectonic considerations require that one source of the CRBG be a plume or, at least, a nonlocal crustal or uppermost mantle source, and R3 is the ideal candidate for that role. R4 is the second source for the Imnaha Basalt, and R5 is the source for the (206)Pb-rich varieties of the Grande Ronde Basalt. R4 and R5 are identified with contamination by local Phanerozoic crust because of their similarity to local crustal Pb and because the rocks which contain them also have Cu contents correlated with their Pb isotopic compositions. R6 is the parent for Pb in all the Saddle Mountain Basalts. This last source appears to have been homogeneous 2150 m.y. ago but has since split into a number of separate, discrete pockets, each with its own characteristic Pb isotopic signature. Some of these appear in individual Saddle Mountain Basalt flows, while other sources have mixed with R4 to produce individual Saddle Mountain Basalt flows of the Ice Harbor

  15. Nd, Sr, Pb, Ar, and O isotopic systematics of Sturgeon Lake kimberlite, Saskatchewan, Canada: constraints on emplacement age, alteration, and source composition

    NASA Astrophysics Data System (ADS)

    Hegner, E.; Roddick, J. C.; Fortier, S. M.; Hulbert, L.

    1995-06-01

    Rb-Sr isotopic dating of phlogopite megacryst samples separated from Sturgeon Lake kimberlite, Saskatchewan, yields a crystallization age of 98±1 Ma (2 σ, MSWD=1.2; 87Sr/86Sr( t)=0.7059). The 40Ar/39Ar analyses of a phlogopite megacryst sample indicate the presence of large amounts of excess 40Ar and yield an excessively old age of ˜410 Ma. Assessment of the Ar data using isotope correlation plots indicates clustering of the data points about a mixing line between the radiogenic 40Ar component at 98 Ma and a trapped component with uniform 36Ar/40Ar and Cl/40Ar. Values of δ 18O as high as +20‰ (VSMOW) for calcite from the groundmass and a whole-rock sample indicate pervasive low-temperature alteration. The δ 13C of matrix carbonate is -11.3‰ (PDB), slightly lighter than typical values from the literature. The δ 18O values of about +5‰ (VSMOW) for brown phlogopite megacrysts may be primary, green phlogopites are interpreted to be an alteration product of the brown variety and are 2‰ heavier. Initial Nd-Sr-Pb isotopic ratios for a whole-rock sample ( ɛ Nd=+0.8; 87Sr/86Sr=0.7063, 206Pb/204Pb=18.67, 207Pb/204Pb=15.54, 208Pb/204Pb=38.97) suggest an affinity with group I kimberlites. Initial ɛ Nd values of +1.7 and +0.5 (87Sr/86Sr( t)=0.7053 and 0.7050) for eclogitic and lherzolitic garnet megacryst samples, and values of 0.0 for two phlogopite megacryst samples reflect an origin from an isotopically evolving melt due to assimilation of heterogeneous mantle. Lilac high-Cr lherzolitic garnet megacrysts give an unusually high ɛ Nd(98. Ma) of +28.6 (87Sr/86Sr=0.7046) indicating a xenocrystic origin probably from the lithospheric mantle. The very radiogenic 87Sr/86Sr and 206Pb/204Pb ratios of the kimberlite are consistent with melting of EM II (enriched) mantle components.

  16. Major element, REE, and Pb, Nd and Sr isotopic geochemistry of Cenozoic volcanic rocks of eastern China: implications for their origin from suboceanic-type mantle reservoirs

    USGS Publications Warehouse

    Basu, A.R.; Wang, Junwen; Huang, Wankang; Xie, Guanghong; Tatsumoto, M.

    1991-01-01

    Major- and rare-earth-element (REE) concentrations and UThPb, SmNd, and RbSr isotope systematics are reported for Cenozoic volcanic rocks from northeastern and eastern China. These volcanic rocks, characteristically lacking the calc-alkaline suite of orogenic belts, were emplaced in a rift system which formed in response to the subduction of the western Pacific plate beneath the eastern Asiatic continental margin. The rocks sampled range from basanite and alkali olivine basalt, through olivine tholeiite and quartz tholeiite, to potassic basalts, alkali trachytes, pantellerite, and limburgite. These rock suites represent the volcanic centers of Datong, Hanobar, Kuandian, Changbaishan and Wudalianchi in northeastern China, and Mingxi in the Fujian Province of eastern China. The major-element and REE geochemistry is characteristic of each volcanic suite broadly evolving through cogenetic magmatic processes. Some of the outstanding features of the isotopic correlation arrays are as follows: (1) NdSr shows an anticorrelation within the field of ocean island basalts, extending from the MORB end-member to an enriched, time-averaged high Rb Sr and Nd Sr end-member (EM1), (2) SrPb also shows an anticorrelation, similar to that of Hawaiian and walvis Ridge basalts, (3) NdPb shows a positive correlation, and (4) the 207Pb 204Pb vs 206Pb 204Pb plot shows linear arrays parallel to the general trend (NHRL) for MORB on both sides of the geochron, although in the 208Pb 204Pb vs 206Pb 204Pb plot the linear array is significantly displaced above the NHRL in a pattern similar to that of the oceanic island basalts that show the Dupal signatures. In all isotope correlation patterns, the data arrays define two different mantle components-a MORB-like component and an enriched mantle component. The isotopic data presented here clearly demonstrate the existence of Dupal compositions in the sources of the continental volcanic rocks of eastern China. We suggest that the subcontinental mantle

  17. Geochemistry of ultrapotassic volcanic rocks in Xiaogulihe NE China: Implications for the role of ancient subducted sediments

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Ying, Jifeng; Zhou, Xinhua; Shao, Ji'an; Chu, Zhuyin; Su, Benxun

    2014-11-01

    The unique eruptions of ultrapotassic volcanic rocks in eastern China reported so far took place in the Xiaogulihe area of western Heilongjiang Province, NE China. These ultrapotassic rocks are characterized by extremely high K2O contents (> 7 wt.%), abnormally unradiogenic Pb isotopic compositions (206Pb/204Pb = 16.44-16.55; 207Pb/204Pb = 15.39-15.46; 208Pb/204Pb = 36.35-36.61), and moderately high 87Sr/86Sr ratios (0.7053-0.7057), which can be basically correlated with those of ultrapotassic igneous rocks distributed widely in northwestern America and Aldan Shield. The positive correlation between 187Os/188Os and 1/Os argues that these ultrapotassic rocks have probably experienced negligible lower continental crust addition (less than 1%) during magma ascent. The high contents of K2O and negative correlation between 87Sr/86Sr and 206Pb/204Pb of these ultrapotassic rocks indicate the presence of a potassic phase, mostly phlogopite, in their mantle source. Their strong fractionation of rare earth elements and lack of Nd-Hf isotopic decoupling reveal a low-degree partial melting of garnet-bearing source rocks. In addition, the low CaO and Al2O3 contents of whole-rock compositions and low Fe/Mn ratios of olivine phenocryst chemistries suggest peridotites rather than pyroxenites as dominant source rocks for the Xiaogulihe ultrapotassic rocks. Based on these distinctive geochemical characteristics, we thus propose that the ultimate mantle source of the Xiaogulihe ultrapotassic volcanic rocks is phlogopite-bearing garnet peridotite within the lower part of the sub-continental lithospheric mantle (SCLM) that had been metasomatized by potassium-rich silicate melts. Combined with the unradiogenic Pb compositions, the most likely source of these potassium-rich silicate melts is the ancient subducted continental-derived sediments (> 1.5 Ga). These ancient subducted sediments, possessing relatively low initial Pb isotopic compositions, had experienced large U/Pb fractionation

  18. Factors controlling elevated lead concentrations in water samples from aquifer systems in Florida

    USGS Publications Warehouse

    Katz, B.G.; Bullen, M.P.; Bullen, T.D.; Hansard, Paul

    1999-01-01

    Concentrations of total lead (Pb) and dissolved Pb exceeded the U.S. Environmental Protection Agency action level of 15 micrograms per liter (mg/L) in approximately 19 percent and 1.3 percent, respectively, of ground-water samples collected during 1991-96 from a statewide network of monitoring wells designed to delineate background water quality of Florida's major aquifer systems. Differences in total Pb concentrations among aquifer systems reflect the combined influence of anthropogenic sources and chemical conditions in each system. A highly significant (p<0.001) difference in median total Pb concentrations was found for water samples from wells with water-level recording devices that contain Pb-counterweights (14 mg/L) compared to non-recorder wells (2 mg/L). Differences between total Pb concentrations for recorder and non-recorder wells are even more pronounced when compared for each aquifer system. The largest differences for recorder status are found for the surficial aquifer system, where median total Pb concentrations are 44 and 2.4 mg/L for recorder wells and non-recorder wells, respectively. Leaching of Pb from metal casing materials is another potential source of Pb in ground water samples. Median total Pb concentrations in water samples from the surficial, intermediate, and Floridan aquifer systems are higher from recorder wells cased with black iron than for recorder wells with steel and PVC casing material. Stable isotopes of Pb were used in this study to distinguish between anthropogenic and natural sources of Pb in ground water, as Pb retains the isotopic signature of the source from which it is derived. Based on similarities between slopes and intercepts of trend lines for various sample types (plots of 206Pb/204Pb versus 208Pb/204Pb and 207Pb/204Pb versus 208Pb/204Pb) the predominant source of total Pb in water samples from the surficial aquifer system is corrosion of Pb counterweights. It is likely that only ground-water samples, not the aquifer

  19. Dynamic variability of dissolved Pb and Pb isotope composition from the U.S. North Atlantic GEOTRACES transect

    NASA Astrophysics Data System (ADS)

    Noble, Abigail E.; Echegoyen-Sanz, Yolanda; Boyle, Edward A.; Ohnemus, Daniel C.; Lam, Phoebe J.; Kayser, Rick; Reuer, Matt; Wu, Jingfeng; Smethie, William

    2015-06-01

    This study presents dissolved Pb concentration and isotopic composition distributions from GEOTRACES GA03, the U.S. North Atlantic Transect. Pb in the ocean is primarily derived from anthropogenic sources and Pb fluxes into the North Atlantic Ocean have been steadily decreasing following the phase-out of alkyl leaded gasoline usage in North America and Europe between 1975 and 1995. A compilation of dissolved Pb profiles from three stations occupied repeatedly during the last three decades reveals a dramatic decrease in concentrations within the surface layers and the thermocline maxima, although elevated concentrations greater than 60 pmol/kg are still observed in the center of the North Atlantic gyre where ventilation timescales are longer than at the western boundary. The evolution of stable Pb isotopes at these stations shows a shift from dominantly North American-like composition in surface waters in the early 1980s towards a more European-like composition in later years. The most recent shallow signatures at the Bermuda Atlantic Time Series station (BATS) show an even more recent trend returning to higher 206Pb/207Pb ratios after the completed phase-out of leaded gasoline in Europe, presumably because recently deposited Pb is more strongly influenced by industrial and incineration Pb than by residual alkyl leaded gasoline utilization. In surface waters, trends toward a more prominent European influence are also found in the middle of the basin and toward the European coast, coincident with higher concentrations of surface dissolved Pb. Scavenging of anthropogenic Pb is observed within the TAG hydrothermal plume, and it is unclear if there is any significant contribution to deep water by basaltic Pb leached by hydrothermal fluids. In the upper water column, many stations along the transect show Pb concentration maxima at ~100 m depth, coincident with a low 206Pb/207Pb isotopic signature that is typical of European emission sources. Although Pb ores from the

  20. The origin of the Maozu carbonate-hosted Pb-Zn deposit, southwest China: Constrained by C-O-S-Pb isotopic compositions and Sm-Nd isotopic age

    NASA Astrophysics Data System (ADS)

    Zhou, Jiaxi; Huang, Zhilong; Yan, Zaifei

    2013-09-01

    The Maozu Pb-Zn deposit, located on the western margin of the Yangtze Block, southwest China, is a typical carbonate-hosted deposit in the Sichuan-Yunnan-Guizhou Pb-Zn metallogenic province with Pb + Zn reserves of about 2.0 million tonnes grading 4.15 wt.% Pb and 7.25 wt.% Zn. Its ore bodies are hosted in Sinian (635-541 Ma) Dengying Formation dolostone and show stratiform, vein and irregular textures. Ores are composed of sphalerite, galena, pyrite, calcite, dolomite, quartz and fluorite with massive, banded, disseminated and veined structures. The C-O-Sm-Nd isotopic compositions of hydrothermal calcites and S-Pb isotopic compositions of sulfides were analyzed to constrain the origin of the Maozu deposit. δ13CPDB and δ18OSMOW values of hydrothermal calcites range from -3.7‰ to -2.0‰ and +13.8‰ to +17.5‰, respectively, and plot near the marine carbonate rocks field in a plot of δ13CPDB vs. δ18OSMOW, with a negative correlation. It suggests that CO2 in the hydrothermal fluids was mainly originated from marine carbonate rocks, with limited influence from sedimentary organic matter. δ34SCDT values of sulfides range from +9.9‰ to +19.2‰, similar to that of Cambrian to Triassic seawater sulfate (+15‰ to +35‰) and evaporate (+15‰ to +30‰) in the Cambrian to Triassic sedimentary strata. It suggests that reduced sulfur was derived from evaporate in sedimentary strata by thermo chemical sulfate reduction. Sulfides have low radiogenic Pb isotope compositions (206Pb/204Pb = 18.129-18.375, 207Pb/204Pb = 15.640-15.686 and 208Pb/204Pb = 38.220-38.577) that plot in the field between upper crust and the orogenic belt evolution curve in the plot of 207Pb/204Pb vs. 206Pb/204Pb, and similar to that of age corrected Proterozoic basement rocks (Dongchuan and Kunyang Groups). This indicates that ore-forming metals were mainly derived from basement rocks. Hydrothermal calcite yields a Sm-Nd isotopic age of 196 ± 13 Ma, possibly reflecting the timing of Pb

  1. Major, trace element and isotope geochemistry (Sr-Nd-Pb) of interplinian magmas from Mt. Somma-Vesuvius (Southern Italy)

    USGS Publications Warehouse

    Somma, R.; Ayuso, R.A.; de Vivo, B.; Rolandi, G.

    2001-01-01

    compositions in the interplinian rocks show a tendency to become slightly more radiogenic with age, from the Protohistoric (143Nd/144Nd=0.51240-0.51247) to Ancient Historic (143Nd/144Nd=0.51245-0.51251). Medieval interplinian activity (143Nd/144Nd: 0.51250-0.51241) lacks meaningful internal trends. All the interplinian rocks have virtually homogeneous compositions of 207Pb/204Pb and 208Pb/204Pb in acid-leached residues (207Pb/204Pb ???15.633 to 15.687, 208Pb/204Pb ???38.947 to 39.181). Values of 206Pb/204Pb are very distinctive, however, and discriminate among the three interplinian cycles of activity (Protohistoric: 18.929-18.971, Ancient Historic: 19.018-19.088, Medieval: 18.964-19.053). Compositional trends of major, trace element and isotopic compositions clearly demonstrate strong temporal variations of the magma types feeding the Somma-Vesuvius activity. These different trends are unlikely to be related only to low pressure evolutionary processes, and reveal variations of parental melt composition. Geochemical data suggest a three component mixing scheme for the interplinian activity. These involve HIMU-type and DMM-type mantle and Calabrian-type lower crust. Interaction between these components has taken place in the source; however, additional quantitative constraints must be acquired in order to better discriminate between magma characteristics inherited from the sources and those acquired during shallow level evolution.

  2. Petrogenesis of pillow basalts from Baolai in southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Liu, Chih-Chun; Yang, Huai-Jen

    2016-04-01

    The pillow basalts from Baolai in southwestern Taiwan have been inferred to bear Dupal signautres based on their Th/Ce ratio, linking the Baolai basalts to the South China Sea (SCS) seamounts that are characterized by Dupal Pb isotope signatures (Smith and Lewis, 2007). In this study, thirty-two Baolai basalt samples were analyzed for abundances of major and trace elements as well as Pb and Nd isotope ratios to verify their Dupal characters and to constrain their petrogenesis significance. The Baolai basalts contain 4-10 % L.O.I.. Three stages of alteration are inferred from plots of L.O.I. abundance versus concentrations major oxides as well as mineral textures and compositions. The first alteration stage was characterized by albitization that converted Ca-rich plagioclase to albite. The second alteration stage was dominated by chloritization of olivine and augite, resulting in increases in L.O.I. abundance. The last alteration stage is represented by formation of secondary calcite in vesicles and cracks. These alteration processes reflect interaction with seawater and apparently did not affect the magmatic Pb isotope composition for the low Pb concentration in seawater. Relative to the North Hemisphere Reference Line (NHRL), the Baolai pillow basalts have higher 208Pb/204Pb ratios at a given 206Pb/204Pb value, showing Dupal anomaly. For their relatively higher 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios, the Baolai basalts are distinct from majority of the Cenozoic basalts in the Hainan-Leizhou peninsula, the Indochina peninsula, and the SCS seamounts, for which derivation from the Hainan mantle plume has been recently proposed (Wang et al., 2013). In contrast, the Baolai basalts and the Cenozoic basalts from eastern Guangdong at southeastern China have similar Pb and Nd isotope compositions, indicating derivation from similar mantle sources. However, the Baolai basalts have lower abundance ratios of Zr/Hf (40.3-45.6 versus 46.5-50.5), La/Yb (12

  3. Reconstructing the environmental impact of smelters using Pb isotope analyses of peat cores from bogs: Flin Flon, Manitoba and Harjavalta, Finland

    NASA Astrophysics Data System (ADS)

    Shotyk, W.

    2012-04-01

    Located on the Manitoba - Saskatchewan border, the city of Flin Flon has been home to a metallurgical complex since 1930, processing Cu and Zn ores from surrounding mines and consisting of a concentrator, Zn plant, and Cu smelter. Peat cores were collected from two sites, dated using 210Pb, and measured for a broad suite of potentially toxic trace metals. A peat core collected from the bog at Kotyk Lake (30 km NE of FF) shows declines in 206Pb/207Pb from the natural "background" values of 1.25 at the base of the core, to a minimum of 1.02. A peat core collected from the bog at Sask Lake (88 km NW of FF) shows declines in 206Pb/207Pb from the natural "background" values of 1.35 at the base of the core to a minimum of 1.05. But the isotopic evolution of Pb shows significantly declines in 206Pb/207Pb beginning in the late 1800's, presumably because of long-range atmospheric transport from other sources. The 206Pb/207Pb values increase in both cores starting in the 1960's, and reach a recent maximum in the 1990's, apparently reflecting the growing use and eventually phase out of leaded gasoline use. Since the 1990's, the 206Pb/207Pb have continued their decline, apparently reflecting the elimination of leaded gasoline and the growing relative importance of Pb from the smelter. The temporal evolution in Pb enrichment factors follows the history of the metallurgical complex, with the maximum EF values (calculated using Sc) reaching maxima of ca. 100 x (Kotyk Lake) and 10 x (Sask Lake). The maximum rates of atmospheric Pb accumulation are approximately 1200 and 120 μg/m2/yr, respectively. In Finland, peat cores were taken from three bogs: the Pyhäsuo mire in SW Finland, 6 km NE from the Cu Ni smelter at Harjavalta (HAR); at the Viurusuo complex in eastern Finland, 8 km SW of the Cu Ni mine in the town of Outokumpu (OUT); and at Hietajärvi (HJ), in the Patvinsuo National Park of eastern Finland. The cores from HJ and OUT document 3,000 years of anthropogenic Pb and

  4. Effect of recent climate change on Arctic Pb pollution: a comparative study of historical records in lake and peat sediments.

    PubMed

    Liu, Xiaodong; Jiang, Shan; Zhang, Pengfei; Xu, Liqiang

    2012-01-01

    Historical changes of anthropogenic Pb pollution were reconstructed based on Pb concentrations and isotope ratios in lake and peat sediment profiles from Ny-Ålesund of Arctic. The calculated excess Pb isotope ratios showed that Pb pollution largely came from west Europe and Russia. The peat profile clearly reflected the historical changes of atmospheric deposition of anthropogenic Pb into Ny-Ålesund, and the result showed that anthropogenic Pb peaked at 1960s-1970s, and thereafter a significant recovery was observed by a rapid increase of (206)Pb/(207)Pb ratios and a remarkable decrease in anthropogenic Pb contents. In contrast to the peat record, the longer lake record showed relatively high anthropogenic Pb contents and a persistent decrease of (206)Pb/(207)Pb ratios within the uppermost samples, suggesting that climate-sensitive processes such as catchment erosion and meltwater runoff might have influenced the recent change of Pb pollution record in the High Arctic lake sediments.

  5. Lead contamination of small cetaceans in European waters--the use of stable isotopes for identifying the sources of lead exposure.

    PubMed

    Caurant, F; Aubail, A; Lahaye, V; Van Canneyt, O; Rogan, E; López, A; Addink, M; Churlaud, C; Robert, M; Bustamante, P

    2006-08-01

    Lead concentrations and isotopic composition have been measured in bone and teeth of small cetaceans belonging to three species (Delphinus delphis, Phocoena phocoena and Stenella coeruleoalba), to evaluate the toxicological risk and to determine sources of lead in the European waters. Lead concentrations, far lower than threshold value inducing toxic effects in human, were higher in teeth than in bones, but highly correlated between the two tissues (r=0.92, p<0.001). Large variations of 206Pb/207Pb values in bone tissue showed that cetaceans must be submitted to various atmospheric influences. No geographical differences appeared which is consistent with studies on their distribution indicating seasonal movements between Brittany waters and the Bay of Biscay. The negative correlation between 206Pb/207Pb ratios and age of the individuals reflected the decrease in the production of alkyl lead in Europe, i.e., the increasing use of unleaded gasoline.

  6. Pb-concentrations and Pb-isotope ratios in soils collected along an east-west transect across the United States

    USGS Publications Warehouse

    Reimann, Clemens; Smith, David B.; Woodruff, Laurel G.; Flem, Belinda

    2011-01-01

    Analytical results for Pb-concentrations and isotopic ratios from ca. 150 samples of soil A horizon and ca. 145 samples of soil C horizon collected along a 4000-km east–west transect across the USA are presented. Lead concentrations along the transect show: (1) generally higher values in the soil A-horizon than the C-horizon (median 21 vs. 16.5 mg/kg), (2) an increase in the median value of the soil A-horizon for central to eastern USA (Missouri to Maryland) when compared to the western USA (California to Kansas) (median 26 vs. 20 mg/kg) and (3) a higher A/C ratio for the central to eastern USA (1.35 vs. 1.14). Lead isotopes show a distinct trend across the USA, with the highest 206Pb/207Pb ratios occurring in the centre (Missouri, median A-horizon: 1.245; C-horizon: 1.251) and the lowest at both coasts (e.g., California, median A-horizon: 1.195; C-horizon: 1.216). The soil C-horizon samples show generally higher 206Pb/207Pb ratios than the A-horizon (median C-horizon: 1.224; A-horizon: 1.219). The 206Pb/207Pb-isotope ratios in the soil A horizon show a correlation with the total feldspar content for the same 2500-km portion of the transect from east-central Colorado to the Atlantic coast that shows steadily increasing precipitation. No such correlation exists in the soil C horizon. The data demonstrate the importance of climate and weathering on both Pb-concentration and 206Pb/207Pb-isotope ratios in soil samples and natural shifts thereof in the soil profile during soil-forming processes.

  7. The lead (Pb) isotope signature, behaviour and fate of traffic-related lead pollution in roadside soils in The Netherlands.

    PubMed

    Walraven, N; van Os, B J H; Klaver, G Th; Middelburg, J J; Davies, G R

    2014-02-15

    In this study the origin, behaviour and fate of anthropogenic Pb in sandy roadside soils were assessed by measuring soil characteristics, Pb isotope composition and content. In 1991 and 2003 samples were taken at different depth intervals at approximately 8 and 75 m from two highways in The Netherlands. The Pb isotope composition of the litter layer ((206)Pb/(207)Pb=1.12-1.14) differs from the deeper soil samples ((206)Pb/(207)Pb=1.20-1.21). Based on a mixing model it is concluded that the samples contain two Pb sources: natural Pb and anthropogenic Pb, the latter mainly derived from gasoline. (206)Pb/(207)Pb ratios demonstrate that the roadside soils were polluted to a depth of ~15 cm. Within this depth interval, anthropogenic Pb content is associated with organic matter. Although Pb pollution only reached a depth of ~15 cm, this does not mean that the topsoils retain all anthropogenic Pb. Due to the low pH and negligible binding capacity of soils at depths >15 cm, anthropogenic Pb migrated towards groundwater after reaching depths of >15 cm. The Pb isotope composition of the groundwater ((206)Pb/(207)Pb=1.135-1.185) establishes that groundwater is polluted with anthropogenic Pb. The contribution of anthropogenic Pb to the groundwater varies between ~30 and 100%. Based on the difference in soil Pb content and Pb isotope compositions over a period of 12 years, downward Pb migration is calculated to vary from 72 ± 95 to 324 ± 279 mg m(-2)y(-1). Assuming that the downward Pb flux is constant over time, it is calculated that 35-90% of the atmospherically delivered Pb has migrated to the groundwater.

  8. The lead (Pb) isotope signature, behaviour and fate of traffic-related lead pollution in roadside soils in The Netherlands.

    PubMed

    Walraven, N; van Os, B J H; Klaver, G Th; Middelburg, J J; Davies, G R

    2014-02-15

    In this study the origin, behaviour and fate of anthropogenic Pb in sandy roadside soils were assessed by measuring soil characteristics, Pb isotope composition and content. In 1991 and 2003 samples were taken at different depth intervals at approximately 8 and 75 m from two highways in The Netherlands. The Pb isotope composition of the litter layer ((206)Pb/(207)Pb=1.12-1.14) differs from the deeper soil samples ((206)Pb/(207)Pb=1.20-1.21). Based on a mixing model it is concluded that the samples contain two Pb sources: natural Pb and anthropogenic Pb, the latter mainly derived from gasoline. (206)Pb/(207)Pb ratios demonstrate that the roadside soils were polluted to a depth of ~15 cm. Within this depth interval, anthropogenic Pb content is associated with organic matter. Although Pb pollution only reached a depth of ~15 cm, this does not mean that the topsoils retain all anthropogenic Pb. Due to the low pH and negligible binding capacity of soils at depths >15 cm, anthropogenic Pb migrated towards groundwater after reaching depths of >15 cm. The Pb isotope composition of the groundwater ((206)Pb/(207)Pb=1.135-1.185) establishes that groundwater is polluted with anthropogenic Pb. The contribution of anthropogenic Pb to the groundwater varies between ~30 and 100%. Based on the difference in soil Pb content and Pb isotope compositions over a period of 12 years, downward Pb migration is calculated to vary from 72 ± 95 to 324 ± 279 mg m(-2)y(-1). Assuming that the downward Pb flux is constant over time, it is calculated that 35-90% of the atmospherically delivered Pb has migrated to the groundwater. PMID:24342096

  9. Lead and stable lead isotope ratios in soil, earthworms, and bones of American woodcock (Scolopax minor) from eastern Canada.

    PubMed

    Scheuhammer, Anton M; Bond, Della E; Burgess, Neil M; Rodrigue, Jean

    2003-11-01

    A study to discriminate among different possible sources of elevated Pb exposure for American woodcock (Scolopax minor) in eastern Canada is described. Undamaged wing bones excised from young-of-the-year woodcock collected from several locations in southern Ontario, southern Quebec, New Brunswick, and Nova Scotia, Canada, along with soil and earthworm (Aporrectodea tuberculata and Lumbricus rubellus) samples from the same sites, were analyzed for total Pb, and stable Pb isotopes. Ignoring six soil samples with high (> 60 microg/g) Pb concentration from the vicinity of Montreal (QC, Canada), the mean soil-Pb concentration for all sites combined was 19 microg/g (dry wt; n = 64), with a mean 206Pb:207Pb ratio of 1.19, values typical for uncontaminated rural soils in eastern North America. In earthworms, Pb concentrations ranged from 2.4 to 865 (microg/g [dry wt], mean = 24 microg/g). Concentrations of Pb in worms and soils were positively correlated (r = 0.71; p < 0.01), and 206Pb:207Pb ratios for worms and soils were also positively correlated (r = 0.54; p < 0.05). However, most young-of-the-year woodcock with high bone-Pb accumulation (> 20 microg/g) had 206Pb:207Pb ratios substantially different from worms and soils sampled from the same areas, even though woodcock feed extensively on soil invertebrates, especially earthworms. The range of 206Pb:207Pb ratios in wing bones of woodcock with elevated Pb exposure was not consistent with exposure to environmental Pb from past gasoline combustion nor Precambrian mining wastes but was consistent with ingestion of spent Pb shotgun pellets. PMID:14587896

  10. Three centuries of heavy metal pollution in Paris (France) recorded by urban speleothems.

    PubMed

    Pons-Branchu, Edwige; Ayrault, Sophie; Roy-Barman, Matthieu; Bordier, Louise; Borst, Wolfgang; Branchu, Philippe; Douville, Eric; Dumont, Emmanuel

    2015-06-15

    The first record of urban speleothems used to reconstruct the history of heavy metal pollution of shallow groundwaters is presented. Two speleothems grew during the last 300 years in an underground aqueduct in the north-eastern part of Paris. They display high Pb, Mn V, Cu, Cd and Al concentrations since 1900 due to the urbanization of the site which triggered anthropogenic contamination of the water feeding the speleothems. Surprisingly, these heavy metal concentrations are also high in the oldest part. This early pollution could come from the use of Parisian waste as fertilizers in the orchards and vineyards cultivated above the aqueduct before urbanization. Lead isotopes were measured in these carbonates as well as in lead artifacts from the 17th-18th centuries ((206)Pb/(207)Pb=1.180+/-0.003). The mean (206)Pb/(207)Pb ratio, for one of the speleothems is 1.181+/-0.003 unvarying with time. These lead signatures are close to those of coal and old lead from northern European mines, lower than the natural background signature. It confirms that the high metal concentrations found come from anthropogenic pollution. Conversely, the lead isotopic composition of the second speleothem presents two temporal trends: for the oldest levels, the mean value (1.183+/-0.003) is similar to the first speleothem. For the youngest part, a lower value (1.172+/-0.005) is recorded, evidencing the contribution of a new lead source at the beginning of the industrial revolution. Pb isotopes were also measured in recent samples from a nearby superficial site. The first sample is a recent (AD 1975+/-15 years) deposit ((206)Pb/(207)Pb=1.148+/-0.003), and the second, a thin subactual layer ((206)Pb/(207)Pb=1.181+/-0.002). These data are compatible with the adding of anthropogenic sources (leaded gasoline and industrial lead from Rio Tinto ore).

  11. Lead and stable lead isotope ratios in soil, earthworms, and bones of American woodcock (Scolopax minor) from eastern Canada.

    PubMed

    Scheuhammer, Anton M; Bond, Della E; Burgess, Neil M; Rodrigue, Jean

    2003-11-01

    A study to discriminate among different possible sources of elevated Pb exposure for American woodcock (Scolopax minor) in eastern Canada is described. Undamaged wing bones excised from young-of-the-year woodcock collected from several locations in southern Ontario, southern Quebec, New Brunswick, and Nova Scotia, Canada, along with soil and earthworm (Aporrectodea tuberculata and Lumbricus rubellus) samples from the same sites, were analyzed for total Pb, and stable Pb isotopes. Ignoring six soil samples with high (> 60 microg/g) Pb concentration from the vicinity of Montreal (QC, Canada), the mean soil-Pb concentration for all sites combined was 19 microg/g (dry wt; n = 64), with a mean 206Pb:207Pb ratio of 1.19, values typical for uncontaminated rural soils in eastern North America. In earthworms, Pb concentrations ranged from 2.4 to 865 (microg/g [dry wt], mean = 24 microg/g). Concentrations of Pb in worms and soils were positively correlated (r = 0.71; p < 0.01), and 206Pb:207Pb ratios for worms and soils were also positively correlated (r = 0.54; p < 0.05). However, most young-of-the-year woodcock with high bone-Pb accumulation (> 20 microg/g) had 206Pb:207Pb ratios substantially different from worms and soils sampled from the same areas, even though woodcock feed extensively on soil invertebrates, especially earthworms. The range of 206Pb:207Pb ratios in wing bones of woodcock with elevated Pb exposure was not consistent with exposure to environmental Pb from past gasoline combustion nor Precambrian mining wastes but was consistent with ingestion of spent Pb shotgun pellets.

  12. Application of lead isotopic methods to the study of the anthropogenic lead provenance in Spanish overbank floodplain deposits.

    PubMed

    Adánez Sanjuán, Paula; Flem, Belinda; Llamas Borrajo, Juan F; Locutura Rupérez, Juan; Garcia Cortés, Angel

    2016-04-01

    Changes in the principal sources of Pb in overbank sediment profiles have been documented for two Spanish areas by using Pb isotopes and Pb concentrations. These locations (Madrid and Tinto-Odiel basin) represent two of the most contaminated regions in Spain. The Community of Madrid is characterized by heavy industrial and urban activity, focused mainly in Madrid City. The Tinto-Odiel basin drains the Iberian Pyrite Belt, which hosts many polymetallic massive sulphides and is heavily affected by mining activities in their headwaters. It has been proven that the influence of anthropogenic activity is reflected in these overbank deposits by variations in Pb concentrations that, in general, correlate with shifts in the (206)Pb/(207)Pb ratio. Rivas profile (downstream of Madrid) was found to be the most anthropogenically influenced site. The sediments within this profile which were recently deposited (170 ± 40 years BP) have the least radiogenic signatures. (206)Pb/(207)Pb ratios ranged between 1.1763 and 1.1876 indicating significant contributions of anthropogenic Pb. In contrast, profiles upstream of Madrid possess an average (206)Pb/(207)Pb ratio of 1.2272. It is difficult to clearly identify the most prominent source as the sediments appear to be characterized by an input from several sources. The floodplain profiles in the Tinto-Odiel basin exhibit uniform (206)Pb/(207)Pb ratios ranging from 1.1627 (Odiel river) to 1.1665 (Tinto river). These ratios are similar to the ones possessed by sulphide ores in the area and differ from the ratios of other nonmineralized formations in the basin, indicating that mining activities are the primary, if not sole, source of Pb to the sediments. PMID:26100323

  13. U-Th-Pb zircon ages of some Keweenawan Supergroup rocks from the south shore of Lake Superior

    USGS Publications Warehouse

    Zartman, R.E.; Nicholson, S.W.; Cannon, W.F.; Morey, G.B.

    1997-01-01

    New single-crystal zircon U-Th-Pb ages for plutonic and rhyolitic Keweenawan Supergroup rocks from the south shore of Lake Superior provide geochronological constraints on magmatic evolution associated with the 1.1 Ga Midcontinent rift. Analyses of a granophyric phase of the Mineral Lake intrusion and the Meilen granite, both parts of the Meilen Intrusive Complex, and a laterally extensive rhyolite from the top of the Kallander Creek Volcanics have weighted average 207Pb/206Pb ages of 1102.0 ?? 2.8 Ma (N = 2), 1100.9 ?? 1.4 Ma (N = 5), and 1098.8 ?? 1.9 Ma (N = 4), respectively. Analyses of a pyroclastic rhyolite flow at the top of the Porcupine Volcanics result in variable 207Pb/206Pb ages that range from 1080 to 1137 Ma. This rhyolite exhibits a continuum between morphologically complex and simpler prismatic zircon crystals, the latter yielding concordant analyses having a weighted average 207Pb/206Pb age of 1093.6 ?? 1.8 Ma (N = 2). Four prismatic zircons from an aphyric rhyolite of the Chengwatana Volcanics in the Ashland syncline form a linear array intersecting concordia at 1094.6 ?? 2.1 Ma (MSWD = 1.3). Another presumed Chengwatana rhyolite recovered from drill core intersecting the Hudson-Afton horst in southeast Minnesota yielded only ???20 morphologically indistinguishable zircons. Six analyses give 207Pb/206Pb ages ranging from 1112 to 1136 Ma, including one analysis with a virtually concordant age of 1130 Ma. This age, however, is considerably older than that obtained for the Chengwatana Volcanics in the Ashland syncline or any other precisely dated rock from the Midcontinent rift.

  14. Probing the source and timing of rejuvenation and hybridization in post-caldera rhyolite magmas at Yellowstone Caldera

    NASA Astrophysics Data System (ADS)

    Till, C.; Vazquez, J. A.; Boyce, J. W.; Stelton, M. E.

    2013-12-01

    We find petrographic, isotopic and geochemical evidence for rejuvenation and recycling of subvolcanic intrusions within low δ18O intracaldera rhyolite lavas erupted following the formation of Yellowstone Caldera. In order to resolve the timing and compositional end-members involved in rejuvenation and hybridization of Yellowstone's subvolcanic magma reservoir, we have analyzed the Pb isotopic composition of clinopyroxene and sanidine phenocrysts and performed U-Pb dating of zircons from the South Biscuit Basin (SBB) and Scaup Lake (SCL) rhyolite lava flows. Both SBB and SCL erupted ca. 260 ka based on indistinguishable 40Ar/39Ar ages [1,2] and represent a renewed episode of postcaldera volcanism after a hiatus of ~200 kyr. Zoned phenocrysts of quartz, clinopyroxene, orthopyroxene, plagioclase, and sanidine and accessory zircon and Fe-Ti oxides characterize both SBB and SCL. SCL and SBB clinopyroxene have identical compositions and core-to-rim zoning patterns in Fe, Mg, and trace elements and commonly exhibit exsolution lamellae in their cores, suggesting that subsolidus conditions were attained during the early evolution of these rhyolites. The exsolution-bearing cores are mantled by a zone of relatively high Mg/Fe and low HREE & Rb, which is in turn overgrown by a rim with slightly lower Mg/Fe, and higher HREE & Rb. This zoning pattern suggests rejuvenation of subsolidus rhyolite by the influx of at least two less evolved, hotter silicic magmas. Diffusion modeling of Fe-Mg concentration profiles in clinopyroxene suggests that these events occurred on the order of 103 yrs prior to eruption. To identify the source of the rejuvenated rhyolite and delimit intra-grain variability, we analyzed the Pb-isotopic compositions of the SBB and SCL clinopyroxene zones via LA-MC-ICPMS. The different zones within SBB and SCL clinopyroxene yield indistinguishable Pb-isotope compositions with 208Pb/206Pb=2.165-2.185 and 207Pb/206Pb=0.882-0.890, which matches the Pb

  15. Lead isotope compositions of Late Cretaceous and early Tertiary igneous rocks and sulfide minerals in Arizona: Implications for the sources of plutons and metals in porphyry copper deposits

    USGS Publications Warehouse

    Bouse, R.M.; Ruiz, J.; Titley, S.R.; Tosdal, R.M.; Wooden, J.L.

    1999-01-01

    Porphyry copper deposits in Arizona are genetically associated with Late Cretaceous and early Tertiary igneous complexes that consist of older intermediate volcanic rocks and younger intermediate to felsic intrusions. The igneous complexes and their associated porphyry copper deposits were emplaced into an Early Proterozoic basement characterized by different rocks, geologic histories, and isotopic compositions. Lead isotope compositions of the Proterozoic basement rocks define, from northwest to southeast, the Mojave, central Arizona, and southeastern Arizona provinces. Porphyry copper deposits are present in each Pb isotope province. Lead isotope compositions of Late Cretaceous and early Tertiary plutons, together with those of sulfide minerals in porphyry copper deposits and of Proterozoic country rocks, place important constraints on genesis of the magmatic suites and the porphyry copper deposits themselves. The range of age-corrected Pb isotope compositions of plutons in 12 Late Cretaceous and early Tertiary igneous complexes is 206Pb/204Pb = 17.34 to 22.66, 207Pb/204Pb = 15.43 to 15.96, and 208Pb/204Pb = 37.19 to 40.33. These Pb isotope compositions and calculated model Th/U are similar to those of the Proterozoic rocks in which the plutons were emplaced, thereby indicating that Pb in the younger rocks and ore deposits was inherited from the basement rocks and their sources. No Pb isotope differences distinguish Late Cretaceous and early Tertiary igneous complexes that contain large economic porphyry copper deposits from less rich or smaller deposits that have not been considered economic for mining. Lead isotope compositions of Late Cretaceous and early Tertiary plutons and sulfide minerals from 30 metallic mineral districts, furthermore, require that the southeastern Arizona Pb province be divided into two subprovinces. The northern subprovince has generally lower 206Pb/204Pb and higher model Th/U, and the southern subprovince has higher 206Pb/204Pb and

  16. SIMS and TIMS U-Th-Pb Geochronology of Zircon From the Bishop Tuff

    NASA Astrophysics Data System (ADS)

    Ickert, R. B.; Magee, C. W.; Mundil, R.

    2013-12-01

    ages of only 80 Ka with a mean age of less than 800 Ka. The precision of single-spot analyses are on the order of 4% (2σ), yielding an absolute precision of approximately × 30 ka per spot. Inferred common 206Pb concentrations are on the order of 2 ppb, yielding fractions of radiogenic 206Pb mostly higher than 98%. Common Pb corrections based on the so-called 207Pb and 208Pb methods yield nearly identical results. The agreement between both common Pb corrections eliminates the possibility of interfering species on the common Pb peak as a source of inaccuracy. These data show no evidence of an old (>850 Ka) component in this sample. There is no excess scatter, allowing the possibility that zircon crystallization took place over a very short period of time (<10 Ka), consistent with TIMS analyses. Single grain TIMS analyses from the same sample also show no evidence for protracted zircon crystallization. Preliminary leaching experiments of multi-grain samples (progressive dissolution) show no variation of Pb/U during individual leaching steps, suggesting that the within-grain age variation may be less than 10 Ka. A more comprehensive study including geochemical and geochronological analyses on volcanic products of the entire Long Valley Suite is crucial to better understand the timing of magma generation, crystal growth and eruptions of this volcanic system.

  17. Effectiveness of leaded petrol phase-out in Tianjin, China based on the aerosol lead concentration and isotope abundance ratio.

    PubMed

    Wang, Wan; Liu, Xiande; Zhao, Liwei; Guo, Dongfa; Tian, Xiaodan; Adams, Freddy

    2006-07-01

    The phase-out of leaded petrol has been a measure widely used to reduce atmospheric lead pollution. Since the 1980s, China began to promote unleaded petrol. In order to assess the effectiveness of the measure an isotope fingerprint technique was applied for aerosol samples in the city of Tianjin. After dilute acid leaching, the lead concentration and isotope abundance ratios were determined for 123 samples collected in Tianjin during eight years (1994-2001). The 206Pb/207Pb ratio was lower in summer, when coal combustion emission was low and vehicle exhaust became more important, indicating that the 206Pb/207Pb ratio of leaded petrol in Tianjin is lower than that of aerosol samples. The 206Pb/207Pb ratio gradually increased from 1994 to 2001, a trend that suggests that the contribution from vehicle exhaust was diminishing. Overall, the measurements matched well with national statistical data of leaded and unleaded petrol production. After the nationwide switch to unleaded gasoline, comprehensive control measures are urgently needed to reduce air lead pollution in China, as aerosol lead reduced slightly but remains at a relatively high level.

  18. Bioavailability of soilborne lead in adults, by stable isotope dilution.

    PubMed Central

    Maddaloni, M; Lolacono, N; Manton, W; Blum, C; Drexler, J; Graziano, J

    1998-01-01

    Using stable isotope dilution, we determined the bioavailability of soilborne lead (Pb) in human adult volunteers. Soil from a residential yard at a mining-impacted federal Superfund site that had negligible amounts of other priority pollutants was dried and screened through a 25-micron mesh sieve. The < 250-micron fraction, which likely represents that ingested via hand-to-mouth activity, was then sterilized by exposure to radiation. Ten replicate samples yielded a mean (SD) soil Pb concentration of 2924 +/- 36 ppm, and a mean 206Pb/207Pb ratio of 1.1083 +/- 0.0002, indicating remarkable soil homogeneity. Six adults with 206Pb/207Pb ratios of > 1.190 were admitted to the clinical research center and fasted overnight prior to dosing with 250 micrograms Pb/70 kg bw (i.e., 85.5 mg soil/70 kg) in a gelatin capsule. Blood for Pb and 206Pb/207Pb ratios was obtained at 14 time points through 30 hr. Results of the isotopic analyses from these subjects indicate that on average 26.2% +/- 8.1 of the administered dose was absorbed. Six additional subjects were subsequently studied but ingested soil immediately after a standardized breakfast. Bioavailability in this group was only 2.52% +/- 1.7. Collectively, this study provides the first experimental estimates of soil Pb absorption in humans, and should allow for more precise estimates of health risks due to Pb-contaminated soil. Images Figure 1 Figure 2 Figure 3 PMID:9860919

  19. Cross-Section Measurements for (n,xn) Reactions by In-Beam Gamma-Ray Spectroscopy

    SciTech Connect

    Pavlik, A.; Baumann, P.; Kerveno, M.; Rudolf, G.; Borcea, C.; Mihailescu, L.C.; Jericha, E.; Raskinyte, I.; Jokic, S.; Lukic, S.; Meulders, J.P.; Nolte, R.; Plompen, A.J.M.

    2005-05-24

    The nuclear reactions 207Pb(n,2n)206Pb and 232Th(n,5n)228Th were studied by measuring prompt gamma-ray emission spectra from the interaction of neutrons with an enriched 207Pb sample and a natTh sample. For 207Pb the measurements were performed at the white neutron beam of the GELINA neutron source at IRMM Geel in the neutron energy range up to 20 MeV. The Th measurements were done at the quasi-monoenergetic 7Li(p,n)7Be neutron source at the Universite Catholique de Louvain for five peak neutron energies in the range 29 MeV to 42 MeV. The measurements were complemented by model calculations using the code system EMPIRE-II.

  20. U-Pb Dating, whole rock and Sr-Nd-Pb-O isotope geochemistry of collisional magmatism in the CACC: Çiçekdaǧ igneous complex (ÇIC)

    NASA Astrophysics Data System (ADS)

    Deniz, Kiymet; Kagan Kadioglu, Yusuf; Stuart, Finlay; Ellam, Rob; Boyce, Adrian; Condon, Daniel

    2015-04-01

    these intrusive rocks have experienced fractional crystallisation coupled with crustal assimilation. The calcalkaline and alkaline series show enrichment in LILE and LREE relative to HFSE and HREE. These rocks have moderate 208Pb/204Pb (38.87-39.16) and 207Pb/204Pb (15.62-15.71) and high 206Pb/204Pb (18.76-18.81). Both trace element and Pb isotope data indicate enriched mantle source (EM-II). Mafic alkaline rocks differed with their low 206Pb/204Pb (17.55-17.62). These rocks are derived from subduction modified lithospheric mantle. The geochemistry and Sr-Nd-O isotope data of ophiolitic rocks and late alkaline dykes are very similar. Both of them have flat REE pattern, high 87Sr/86Sr and 143Nd/144Nd, low δ18O values (1.9-4.0), moderate 208Pb/204Pb (38.81-38.97, 38.51-38.91) and 207Pb/204Pb (15.62-15.70, 15.54-15.69) and high 206Pb/204Pb (18.37-18.77, 18.39-18.73). All data indicate heterogeneous mantle source. Trace element ratio diagrams suggest depleted mantle source and subduction enrichment for late alkaline dykes. Dy versus Dy/Yb diagram and calculated partial melting curves suggest 20-25% degree of partial melting of amphibole-phlogopite bearing spinel lherzolitic mantle sources. Ba/Rb versus Rb/Sr diagram indicate the presence of amphibole in the mantle source of ophiolitic rocks and phlogopite for the late alkaline dykes. U-Pb dating of zircon yielded crystallization ages of 73.74±0.027-73.78±0.046 and 73.78±0.071 for calcalkaline series and alkaline series, respectively. Both series are coexistence and may have coevally been confined from same sources.

  1. Cenozoic Bimodal Volcanic Rocks of the Northeast boundary of Tibetan Plateau: implication for the collision-induced mantle flow beneath the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yu, X.; Mo, X.; Zhao, Z.

    2011-12-01

    Cenozoic bimodal volcanic rocks of the Northeastern boundary of Tibetan Plateau are found in the area of West Qinling in China, E104°30'-105°36' and N33°35'-34°40',which located tectonically to the western boundary of Ordos block and also the north section of the N-S trending Helan mountain-Liupan mountain-Yunnan tectonic belt. The geological setting of the bimodal volcanic rocks belongs to an assemblage of Cratonic blocks composed of many small blocks linked by oroginic belts(Deng et al., 1996). The bimodal volcanic rocks, similar to those in East African rift, are consisted of kamafugite, volcanic eruption carbonatite, shoshonite, rhyolite and/or trachyte. The age of the bimodal volcanic rocks is between 23Ma to 7.1Ma according to isotopic dating of K/Ar and 39Ar/40Ar. All of these volcaic rocks in the volcanic assemblage have the characteristics rich in LREE and LIL. Not only that, the HFS, especially Nb, Zr and P in the volcanic rocks are higher than other Cenozoic alkaline volcanic rocks in Tibetan Plateau. The 87Sr/86Sr=0.704031-0.70525, 206Pb/204Pb=18.408-19.062, 207Pb/204Pb=15.476-15.677, 208Pb/204Pb=38.061-39.414 and ɛ(Nd) =0.3-5.3 of the volcanic rocks, all of these are akin to the feature of Neo-Tethyan mantle geochemical end member as represented by Yaluzangbu ophiolites defined by Zhao and Mo et al (2009), and also akin to the volcanic rocks related to Ontong Java and FOZO mantle plum(Yu et al.,2009). Cenozoic bimodal volcanic rocks in Western Qinling, Northeastern boundary of Tibetan Plateau provide ideal lithoprobes for understanding of the mantle beneath Tibetan Plateau and showed that the Cenozoic bimodal volcanic rocks bear the geochemical feature of Indian ocean mantle domain, and its genesis may be related to mantle plum, the magmatic source of the bimodal volcanic rocks should be a depleted mantle. For this reason, we suggest the bimodal volcaic rock is a rifting magmatisim, and its origin and genesis of the bimodal volcaic rocks of

  2. Geochemical and isotopic perspectives on the origin and evolution of the Siletzia Terrane.

    NASA Astrophysics Data System (ADS)

    Phillips, B. A.; Weis, D.; Mullen, E.; Kerr, A. C.

    2015-12-01

    The Siletzia terrane, located in the Cascadia forearc region of Oregon, Washington and Vancouver Island, consists of a series of accreted basaltic pillow lavas, massive flows and intrusive sheets. It represents a late Paleocene-Eocene oceanic large igneous province (LIP), previously proposed to represent an accreted oceanic plateau, hotspot island chain, backarc basin, island arc, or a sequence of slab window volcanics formed by ridge subduction. A province-wide geochemical reassessment of the terrane, including new high precision Sr-Pb-Nd-Hf isotope data on basaltic samples, has been used to assess the validity of the proposed tectonomagmatic models for Siletzia. The trace element data show REE patterns that are flat to LREE enriched with an absence of any arc signatures. These features are comparable to other oceanic plateaus such as the Ontong Java and the Caribbean and so therefore support a mantle plume origin. Initial isotope ratios range from 206Pb/204Pb = 18.869 - 19.673, 207Pb/204Pb = 15.527 - 15.609, 208Pb/204Pb = 38.551 - 39.220, ɛHf = +9.0 - 14.8, ɛNd = +5.0 - 8.0 and 87Sr/86Sr = 0.70304 - 0.70397. The isotope signatures become more varied southward across the terrane and reveal two trends: i) HIMU-DMM and ii) another extending from DMM towards the Imnaha component, thought to represent the mantle plume source of the Columbia River Basalts and Yellowstone 1,2. The data may support the previously proposed idea that the volcanism of the Siletzia terrane represents initial melting of the mantle plume head of the Yellowstone hotspot 3,4,5. Other evidence indicating a LIP origin includes the relatively rapid eruption/intrusion of an estimated magma volume of 2.6 x 106 km3 6 between ~56-49 Ma 5, which, in conjunction with our new elemental and isotopic data, indicates that the Siletzia terrane most likely represents an accreted oceanic plateau. 1. Wolff et al., (2008) Nature Geoscience 1, 177-180. 2. Jean et al., (2014) EPSL 389, 119-131 3. Duncan (1982

  3. Isotope geochemistry and fluid inclusion study of skarns from Vesuvius

    USGS Publications Warehouse

    Gilg, H.A.; Lima, A.; Somma, R.; Belkin, H.E.; de Vivo, B.; Ayuso, R.A.

    2001-01-01

    We present new mineral chemistry, fluid inclusion, stable carbon and oxygen, as well as Pb, Sr, and Nd isotope data of Ca-Mg-silicate-rich ejecta (skarns) and associated cognate and xenolithic nodules from the Mt. Somma-Vesuvius volcanic complex, Italy. The typically zoned skarn ejecta consist mainly of diopsidic and hedenbergitic, sometimes "fassaitic" clinopyroxene, Mg-rich and Ti-poor phlogopite, F-bearing vesuvianite, wollastonite, gehlenite, meionite, forsterite, clinohumite, anorthite and Mg-poor calcite with accessory apatite, spinell, magnetite, perovskite, baddeleyite, and various REE-, U-, Th-, Zr- and Ti-rich minerals. Four major types of fluid inclusions were observed in wollastonite, vesuvianite, gehlenite, clinopyroxene and calcite: a) primary silicate melt inclusions (THOM = 1000-1050??C), b) CO2 ?? H2S-rich fluid inclusions (THOM = 20-31.3??C into the vapor phase), c) multiphase aqueous brine inclusions (THOM = 720-820??C) with mainly sylvite and halite daughter minerals, and d) complex chloride-carbonate-sulfate-fluoride-silicate-bearing saline-melt inclusions (THOM = 870-890??C). The last inclusion type shows evidence for immiscibility between several fluids (silicate melt - aqueous chloride-rich liquid - carbonate/sulfate melt?) during heating and cooling below 870??C. There is no evidence for fluid circulation below 700??C and participation of externally derived meteoric fluids in skarn formation. Skarns have considerably variable 206Pb/204Pb (19.047-19.202), 207Pb/204Pb (15.655-15.670), and 208Pb/204Pb (38.915-39.069) and relatively low 143Nd/144Nd (0.51211-0.51244) ratios. The carbon and oxygen isotope compositions of skarn calcites (??13CV-PDB = -5.4 to -1.1???; ??18OV-SMOW = 11.7 to 16.4???) indicate formation from a 18O- and 13C-enriched fluid. The isotope composition of skarns and the presence of silicate melt inclusion-bearing wollastonite nodules suggests assimilation of carbonate wall rocks by the alkaline magma at moderate depths (< 5

  4. Geochemistry and petrogenesis of carbonatites from South Nam Xe, Lai Chau area, northwest Vietnam

    NASA Astrophysics Data System (ADS)

    Nguyen Thi, Thuy; Wada, Hideki; Ishikawa, Tsuyoshi; Shimano, Taketo

    2014-06-01

    This paper presents a study of the petrography, mineral chemistry, geochemistry, and Sr-Nd-Pb-C-O isotope systematics of carbonatite dykes and associated rocks from the northeastern part of the Song Da intracontinental rift in South Nam Xe (northwest Vietnam) aimed at constraining the origin of the carbonatite magmas. The carbonatites are characterized by SiO2 < 12.18 wt.% and by wide ranges in FeO, MgO and CaO content that define them as calciocarbonatite and ferrocarbonatite. On U-Th-Pb isochron diagrams, whole rocks and mineral separates from the ferrocarbonatites form linear arrays corresponding to ages of 30.2-31.6 Ma (Rupelian, Oligocene). The South Nam Xe carbonatites are extremely enriched in Sr, Ba, and light rare earth elements (LREE), and depleted in high field strength elements (HFSE) (e.g. Ti, Nb, Ta, Zr and Hf). The age-corrected Sr-Nd-Pb isotope ratios and C isotope data are relatively uniform (87Sr/86Sr(t) = 0.708193-0.708349; 143Nd/144Nd(t) = 0.512250-0.512267; ɛNd(t) = -6.46 to -6.80; 206Pb/204Pb(t) = 18.26-18.79; 207Pb/204Pb(t) = 15.62-15.64; 208Pb/204Pb(t) = 38.80-39.38; δ13CV-PDB = -2.7 ‰ to -4.1 ‰). These isotopic compositions indicate source contamination that occurred before the production of the carbonatite magmas, and did not change noticeably during or after emplacement. The variation in oxygen isotopes is consistent with the change in mineral compositions and trace element abundances: the lower δ18O values (9.1-11.0 ‰) coupled with Sr-rich, Mn-poor calcite, and igneous textures such as triple junctions among calcite grain boundaries, define a magmatic origin. However, the elevated δ18O values of the ferrocarbonatites (12.0-13.3 ‰) coupled with a volatile-bearing mineral assemblages (including REE fluorcarbonates, sulfates, sulfides and fluorite) may be due to interaction with meteoric water during low-temperature alteration. High δ13C values and Sr-Pb ratios, and low Rb/Sr (0.00014-0.00301), Sm/Nd (0.089-0.141) and 143Nd/144

  5. Asthenosphere versus lithosphere as possible sources for basaltic magmas erupted during formation of the Red Sea: constraints from Sr, Pb and Nd isotopes

    NASA Astrophysics Data System (ADS)

    Altherr, Rainer; Henjes-Kunst, Friedhelm; Baumann, Albrecht

    1990-01-01

    Representative basalts from the axial trough of the Red Sea and from volcanic fields of the Arabian Peninsula ranging in composition from N-type MORB to basanite and in age from Early Miocene to Recent show a limited variation in their isotopic compositions: 87Sr/ 86Sr= 0.70240-0.70361 , 206Pb/ 204Pb= 18.040-19.634 , 207Pb/ 204Pb= 15.496-15.666 , 208Pb/ 204Pb= 37.808-39.710 , 143Nd/ 144Nd= 0.513194-0.512670 . There is a poorly constrained correlation between chemical composition and isotope ratios: with increasing alkalinity, Sr and Pb isotope ratios increase and the Nd isotope ratio tends to decrease. In Pb isotope variation diagrams most of the basalts plot significantly above the NHRLs, irrespective of tectonic setting, i.e. thickness of underlying crust and/or lithosphere. MORBs from the axial trough of the Red Sea have higher Pb isotope ratios for a given 87Sr/ 86Sr than MORBs from the Indian Ocean ridges, including the Carlsberg Ridge. It is therefore suggested that both spreading ridges tap different convective systems in the asthenosphere. The tectonic setting of the basalts is reflected in their Nd sbnd Sr isotope characteristics. Basalts from areas where the continental lithosphere is drastically thinned or absent (i.e. Red Sea axial trough and coastal plain, Afar) plot along a reference line defined by N-type MORB and Tristan da Cunha. Basalts erupted in areas with Pan-African crust of normal thickness and moderately thinned lithospheric mantle (i.e. rift shoulder) are characterized by relative low 143Nd/ 144Nd ratios and plot below the reference line towards an EM I component which is also found in the subcontinental lithospheric mantle. These differences in the Nd sbnd Sr isotopic compositions of the basalts are independent of bulk-rock chemistry and are therefore controlled by tectonic setting alone. It is suggested that the low- 143Nd/ 144Nd trend of basalts from the Arabian rift shoulder is caused by a significant contribution of the pre

  6. The geology of the carbonate-hosted Blende Ag-Pb-Zn deposit, Wernecke Mountains, Yukon, Canada

    NASA Astrophysics Data System (ADS)

    Moroskat, Micheal; Gleeson, Sarah A.; Sharp, R. J.; Simonetti, A.; Gallagher, C. J.

    2015-01-01

    The Ag-Zn-Pb Blende deposit is located in the Wernecke Mountains, Yukon and is hosted by the middle Proterozoic Gillespie Lake Group dolomitic siltstones. The sulphide mineralization is localized within the axial planar cleavage of a kilometre-scale anticline and is dominated by galena- and sphalerite-cemented mosaic, rubble and crackle breccias with minor pyrite, galena, sphalerite and dolomite veins. 206Pb/204Pb values from galena range from 16.355 to 16.600, 207Pb/204Pb from 15.430 to 15.461, and 208Pb/204Pb from 36.016 to 36.283, respectively, and yield model ages between 1,490 and 1,430 Ma. A hydrothermal alteration zone, which is younger than the mineralization, has a poorly constrained U-Pb monazite age of 1,307 ± 180 Ma, which suggests that the Blende deposit is Proterozoic in age. Dolomites associated with the main- and late-stage mineralization have δ13C values that range from -1.8 to 0.9 ‰ and δ18O values of 15.7 to 21.9 ‰. The total range of δ34S values from pyrite, galena and sphalerite is 9.4 to 58.1 ‰, indicating that the sulphur in the deposit was derived from reduction of seawater sulphate in a closed system. Strontium isotopes suggest there were three fluids involved in the Blende mineralizing system: Fluid 1 was derived from seawater and formed carbonate and quartz veins pre-mineralization; it has an 87Sr/86Sr ratio of 0.70948. Fluid 2 has a high 87Sr/86Sr ratio of 0.73866, and fluid 3 has a Sr isotopic ratio of 0.71602. Fluids 1 and 3 have similar isotopic compositions but different total Sr ion signals (a function of concentration). This suggests that fluids 1 and 3 may have ultimately been derived from Proterozoic seawater but have undergone different amounts of water-rock interaction. The isotopic and geochemical data suggest the mineralization formed when a H2S-rich fluid derived from seawater (fluid 3) mixed with a metal-bearing fluid (fluid 2) in the high permeability zones of the axial planar cleavage. The Blende deposit is an

  7. Geochemical and isotopic constraints on the genesis of the Jueluotage native copper mineralized basalt, Eastern Tianshan, Northwest China

    NASA Astrophysics Data System (ADS)

    Zhang, Dayu; Zhou, Taofa; Yuan, Feng; Fiorentini, Marco L.; Said, Nuru; Lu, Yongjun; Pirajno, Franco

    2013-09-01

    The Jueluotage native copper mineralized basalt is located in the Jueluotage Volcanic-sedimentary Belt, Eastern Tianshan, Xinjiang Uygur Autonomous region. The basalt, amygdaloidal basalt and tuff, which host native copper mineralization, were erupted in the lower strata of the Late Carboniferous Matoutan Formation. Whole-rock geochemistry shows that the basaltic occurrences at Shilipo, Heilongfeng, Changchengshan and Dongjianfeng have fractionated chondrite-normalized REE distributions and distinctly negative primitive mantle-normalized Nb, Ta and Ti anomalies. The whole-rock strontium, neodymium and lead isotopic data indicate low εSr(t) (-7.9 to +23.6), high εNd(t) (+2.5 to +7.1), with restricted 206Pb/204Pb (18.152-18.491), 207Pb/204Pb (15.521-15.562) and 208Pb/204Pb (37.978-38.251) ranges. On the basis of these data, we report that the Cu-bearing basalt is associated with high-iron tholeiitic basalts that were sourced from depleted continental lithosphere mantle garnet-bearing peridotite. The primary magma of the Cu-bearing basalt was: (1) relatively low in silica and magnesium; and (2) underwent only slight olivine and clinopyroxene crystal fractionation during the magmatic evolution process. In the Jueluotage belt, the Shilipo basalt lavas display significant geochemical similarities to numerous mafic intrusions that are present throughout the Jueluotage belt. Those mafic lavas and intrusions probably represent successive pulses of mafic magmatism, which lasted between ca. 310 and 270 Ma. A crucial empirical observation is that the Jueluotage volcanic-sedimentary belt is a well-known metallogenic province that contains a wide range of copper, nickel, gold, and iron mineral deposits. These mineral systems were formed at different times and are associated with radically different ore-forming processes. However, they are all within the Jueluotage belt, which is interpreted to be a suture zone between the Junggar and Tarim plates, northwestern China. We

  8. Lead isotopes in North Pacific deep water - Implications for past changes in input sources and circulation patterns

    USGS Publications Warehouse

    van de Flierdt, T.; Frank, M.; Halliday, A.N.; Hein, J.R.; Hattendorf, B.; Gunther, D.; Kubik, P.W.

    2003-01-01

    The sources of non-anthropogenic Pb in seawater have been the subject of debate. Here we present Pb isotope time-series that indicate that the non-anthropogenic Pb budget of the northernmost Pacific Ocean has been governed by ocean circulation and riverine inputs, which in turn have ultimately been controlled by tectonic processes. Despite the fact that the investigated locations are situated within the Asian dust plume, and proximal to extensive arc volcanism, eolian contributions have had little impact. We have obtained the first high-resolution and high-precision Pb isotope time-series of North Pacific deep water from two ferromanganese crusts from the Gulf of Alaska in the NE Pacific Ocean, and from the Detroit Seamount in the NW Pacific Ocean. Both crusts were dated applying 10 Be/9Be ratios and yield continuous time-series for the past 13.5 and 9.6 Myr, respectively. Lead isotopes show a monotonic evolution in 206Pb/204Pb from low values in the Miocene (??? 18.57) to high values at present day (??? 18.84) in both crusts, even though they are separated by more than 3000 km along the Aleutian Arc. The variation exceeds the amplitude found in Equatorial Pacific deep water records by about three-fold. There also is a striking similarity in 207Pb/204Pb and 208Pb/ 204Pb ratios of the two crusts, indicating the existence of a local circulation cell in the sub-polar North Pacific, where efficient lateral mixing has taken place but only limited exchange (in terms of Pb) with deep water from the Equatorial Pacific has occurred. Both crusts display well-defined trends with age in Pb-Pb isotope mixing plots, which require the involvement of at least four distinct Pb sources for North Pacific deep water. The Pb isotope time-series reveal that eolian supplies (volcanic ash and continent-derived loess) have only been of minor importance for the dissolved Pb budget of marginal sites in the deep North Pacific over the past 6 Myr. The two predominant sources have been young

  9. Provenancing anthropogenic Pb within the fluvial environment: developments and challenges in the use of Pb isotopes.

    PubMed

    Bird, Graham

    2011-05-01

    The potentially deleterious presence of ore-derived Pb within riverine environments has been a long-term impact of industrial and anthropogenic activity in general. The surface drainage network has been widely established as a key transport mechanism and storage environment for anthropogenically-derived Pb and other potentially harmful trace metals. Lead isotopes ((204)Pb, (206)Pb, (207)Pb, (208)Pb) have been utilized as a geochemical tracer of Pb origin in a variety of environmental media, notably in atmospheric aerosols. However, given the relative complexity of dispersal processes within riverine environments, the use of Pb isotopes as geochemical tracers has been relatively limited and it is only relatively recently that a growing body of research has applied Pb isotopes to provenancing fluvially-dispersed Pb. This paper seeks to synthesize the developments in the use of Pb isotopes within riverine environments. In doing so it outlines the Pb-isotope fingerprinting technique and associated analytical developments, and assesses the application of Pb isotopes in establishing the origin and dispersal mechanisms of anthropogenically- and geogenically-derived Pb at a range of temporal and spatial scales. Of particular importance are the approaches quantifying source inputs using Pb isotopic signatures and the challenges faced, and options available in quantifying source inputs at the catchment scale; where Pb may be sourced from a variety (n=>2) of sources. The Pb isotopic signature of contemporary riverine Pb loads is shown to reflect a spatially complex influence of mineralization chemistry, anthropogenic activity as well as the hydro-morphological controls exerted upon Pb release, dispersal and storage. In relation to this, the long-term environmental legacy, and its influence upon Pb fingerprinting studies, of tetra-ethyl Pb, sourced from the combustion of leaded-petrol is also discussed. Finally, this paper places the use of Pb isotopes in the context of

  10. U Pb zircon age, geochemical and Sr Nd Pb Hf isotopic constraints on age and origin of alkaline intrusions and associated mafic dikes from Sulu orogenic belt, Eastern China

    NASA Astrophysics Data System (ADS)

    Liu, Shen; Hu, Ruizhong; Gao, Shan; Feng, Caixia; Qi, Youqiang; Wang, Tao; Feng, Guangying; Coulson, Ian M.

    2008-12-01

    Post-orogenic alkaline intrusions and associated mafic dikes from the Sulu orogenic belt of eastern China consist of quartz monzonites, A-type granites and associated mafic dikes. We report here U-Pb zircon ages, geochemical data and Sr-Nd-Pb-Hf isotopic data for these rocks. The SHRIMP U-Pb zircon analyses yield consistent ages ranging from 120.3 ± 2.1 Ma to 126.9 ± 1.9 Ma for five samples from the felsic rocks, and two crystallization ages of 119.0 ± 1.7 Ma and 120.2 ± 1.9 Ma for the mafic dikes. The felsic rocks and mafic dikes are characterized by high ( 87Sr/ 86Sr) i ranging from 0.7079 to 0.7089, low ɛNd( t) values from - 15.3 to - 19.2, 206Pb/ 204Pb = 16.54-17.25, 207Pb/ 204Pb = 15.38-15.63, 208Pb/ 204Pb = 37.15-38.45, and relatively uniform ɛHf( t) values of between - 21.6 ± 0.6 and - 23.7 ± 1.0, for the magmatic zircons. The results suggest that they were derived from a common enriched lithospheric mantle source that was metasomatized by foundered lower crustal eclogitic materials before magma generation. Geochemical and isotopic characteristics imply that the primary magma to these rocks originated through partial melting of ancient lithospheric mantle that was variably hybridized by melts derived from foundered lower crustal eclogite. The mafic dikes may have been generated by subsequent fractionation of clinopyroxene, whereas the felsic rocks resulted from fractionation of potassium feldspar, plagioclase and ilmenite or rutile. Both were not affected by crustal contamination. Combined with previous studies, these findings provide new evidence that the intense lithospheric thinning beneath the Sulu belt of eastern China occurred between 119 and 127 Ma, and that this was caused by the removal of the lower lithosphere (mantle and lower crust).

  11. Sr-Nd-Hf-Pb isotopic constraints on the origin of silicic lavas in the northern Cascade Arc

    NASA Astrophysics Data System (ADS)

    Martindale, M.; Mullen, E.; Weis, D.

    2015-12-01

    The Cascade Arc is the type-locality for a 'hot' subduction zone, where the downgoing slab is young and subduction is relatively slow; a unique setting for studying the controls on silicic (>56 wt% SiO2) magma genesis [1,2]. We present high precision Sr-Nd-Hf-Pb isotopic and trace element data for silicic lavas and country rocks from the major centres of the Garibaldi Volcanic Belt (GVB) in British Columbia, which are hosted by the Mesozoic Coast Plutonic Complex and accreted Coast Belt terranes. In isotopic plots, the silicic GVB lavas define mixing curves between northern Cascadia Basin sediment [3] and Juan de Fuca MORB. The silicic GVB lavas have lower ɛNd, and higher ɛHf, 87Sr/86Sr, 208Pb/204Pb and 207Pb/204Pb for a given 206Pb/204Pb than co-existing alkalic mafic lavas [2,4] which define a separate isotopic cluster. The alkalic mafic lavas have OIB-like trace element compositions [2,4], but the silicic lavas are calc-alkaline with a typical 'arc' trace element signature. Geochemical systematics suggest that a mafic, isotopically 'depleted' contaminant may be affecting the composition of GVB silicic lavas. However, modelling indicates that slab melts do not constitute a major component of the lavas despite high slab temperatures. Geochemical models also rule out the accreted Coast Belt terranes as an assimilant. However, AFC modelling using 147 Ma Cloudburst quartz diorite [5] as the assimilant can explain both the trace element and isotopic compositional range displayed by GVB silicic magmas, consistent with the Coast Plutonic Complex as a major component of the deep crust in this region. Crustal assimilation would have partially overprinted any alkalic mantle-derived signature of parental magmas, while imparting a calc-alkaline arc signature to resulting silicic magmas. [1] Green & Harry (1999) EPSL, 171; [2] Mullen & Weis (2013) G3, 14; [3] Carpentier et al. (2014) Chem Geol, 382; [4] Mullen & Weis (2015) EPSL, 414; [5] Friedman & Armstrong (1995) GSA

  12. Timescales of magma differentiation from basalt to andesite beneath Hekla Volcano, Iceland: Constraints from U-series disequilibria in lavas from the last quarter-millennium flows

    NASA Astrophysics Data System (ADS)

    Chekol, Takele A.; Kobayashi, Katsura; Yokoyama, Tetsuya; Sakaguchi, Chie; Nakamura, Eizo

    2011-01-01

    Measurements of 238U- 230Th- 226Ra disequilibria, Sr-Nd-Pb-Hf isotopes and major-trace elements have been conducted for lavas erupted in the last quarter-millennium at Hekla volcano, Iceland. The volcanic rocks range from basalt to dacite. Most of the lavas (excluding dacitic samples) display limited compositional variations in radiogenic Sr-Nd-Pb-Hf isotopes ( 87Sr/ 86Sr = 0.70319-0.70322; 143Nd/ 144Nd = 0.51302-0.51305; 206Pb/ 204Pb = 19.04-19.06; 207Pb/ 204Pb = 15.53-15.54; 208Pb/ 204Pb = 38.61-38.65; 176Hf/ 177Hf = 0.28311-0.28312). All the samples possess ( 230Th/ 238U) disequilibrium with 230Th excesses, and they show systematic variations in ( 230Th/ 232Th) and ( 238U/ 232Th) ratios. The highest 226Ra excesses occur in the basalt and most differentiated andesite lavas, while some basaltic-andesite lavas have ( 226Ra/ 230Th) ratio that are close to equilibrium. The 238U- 230Th- 226Ra disequilibria variations cannot be produced by simple closed-system fractional crystallization with radioactive decay of 230Th and 226Ra in a magma chamber. A closed-system fractional crystallization model and assimilation and fractional crystallization (AFC) model indicate that the least differentiated basaltic andesites were derived from basalt by fractional crystallization with a differentiation age of ˜24 ± 11 kyr, whereas the andesites were formed by assimilation of crustal material and fractionation of the basaltic-andesites within 2 kyr. Apatite is inferred to play a key role in fractionating the parent-daughter nuclides in 230Th- 238U and 226Ra- 230Th to make the observed variations. Our proposed model is that several batches of basaltic-andesite magmas that formed by fractional crystallization of a basaltic melt from a deeper reservoir, were periodically injected into the shallow crust to form individual magma pockets, and subsequently modifying the original magma compositions via simultaneous assimilation and fractional crystallization. The assimilant is the dacitic

  13. Geochemical and Sr-Nd-Pb Isotopic Insights of the Low-Ti basalts from Paraná-Etendeka Igneous Province, Southern Brazil: Constraints on Petrogenesis and the Role of Crustal Contamination

    NASA Astrophysics Data System (ADS)

    Raposo, I.; Barreto, C. J.; Lima, E. F. D.; Lafon, J. M.; Sommer, C. A.; Waichel, B. L.

    2015-12-01

    The south hinge of the Torres Syncline in southernmost Brazil hosts a volcanic succession of pahoehoe and rubbly Gramado-type lavas belonging to the ~132 Ma Paraná-Etendeka Igneous Province. We employ local-scale stratigraphy in three distinct profiles (Santa Cruz do Sul-Herveiras, Morro da Cruz and Lajeado geologic sections) as guidelines for geochemical and Sr-Nd-Pb isotope studies in order to discuss the petrogenesis of lava flows in a single magma type and to quantitatively evaluate the role of crustal contamination and the potential contaminants involved. In all profiles, the lava flows exhibit compositions ranging from basalt to andesite with tholeiitic affinity. The compositional and isotopic variations are not systematic according to stratigraphy, implying that the magma chamber could have undergone periodic replenishments or distinct magma pulses through time or multiple plumbling systems may have existed. The andesites (SiO2 55-58 wt.%) with ponded pahoehoe morphology represent evolved melts at early stages of volcanism with strong susceptibility to crustal contamination as they established pathways to the surface. The olivine basalts (SiO2 47-50 wt.%) and basaltic andesites (SiO2 51-56 wt.%) showing compound morphology and simple pahoehoe morphology, respectively, could be explained by longer time residence of liquids in the crust with higher degrees of crustal assimilation than the ponded pahoehoe lavas. The basaltic andesites (SiO2 52-56 wt. %) with rubbly morphology are related to late differentiation process in shallow magma chambers. Crustal assimilation process accounts for the high initial 87Sr/86Sr ratios at 0.707798-0.715751, very low ɛNd between -8.36 and -5.41, high 206Pb/204Pb ratios at 18.424-18.865, with intermediate 207Pb/204Pb and 208Pb/204Pb ratios at 15.649-15.710 and 38.618-39.369, respectively. The isotopic variations require assimilation of both Paleoproterozoic and Neoproterozoic contaminants at variable degrees.

  14. Petrology and Geochemistry of the Eocene Volcanic Rocks in the Kahrizak Mountains, Central Iran

    NASA Astrophysics Data System (ADS)

    Yazdani, S.; Castillo, P.; Tutti, F.

    2013-12-01

    The Eocene volcanic rocks in the Kahrizak (KH) Mountains in the northern part of Central Iran were mainly formed by magmatism that accompanied block-faulting tectonism in the region. In the KH area, the volcanic rocks are nonconformably overlain by Oligocene-Pliocene sedimentary deposits, suggesting that the Eocene magmatic activity in the region was followed by a sequence of uplift and shallow marine regression. The volcanic rocks consist of pyroclastics (tuff and ignimbrites) and lava flows (basalt, basaltic trachyandesite, trachyandesite, and rhyolite); superposition indicates an earlier explosive volcanic phase that caused the widespread distribution of rhyolitic ignimbrites and tuffs, and this was followed by a quieter phase of lava eruptions. Petrographic evidence such as mineral zoning, sieve texture and rounded crystals of plagioclase and pyroxene phenocrysts indicate non-equilibrium conditions between melt and crystals during magma cooling. These textures suggest magma mixing, although these may also be due to rapid decompression, where heat loss is minor relative to the ascent rate. The geochemistry of KH samples indicates their subalkaline to alkaline affinity. In terms of trace element contents, most samples exhibit the distinct geochemical trait of arc volcanism, i.e., Nb and Ta depletions relative to LILE (e.g., Ba, Rb) enrichment and positive Sr anomaly; however, Zr and Ti depletions are not prominent. The samples have a light-REE enriched but flat heavy-REE pattern and negative Eu anomaly in the rhyolites and trachyandesites. They have a ~narrow to ~moderate range of Pb isotopic ratios (206Pb/204Pb ~18.6-18.9, 207Pb/204Pb ~15.5-15.6, and 208Pb/204Pb ~38.5-38.8), with basaltic rocks somewhat higher than rhyolitic rocks. Available geochemical and isotopic data suggest a complex origin and evolution of the KH magmas. The magmas originated from an intrinsically ~heterogeneous source and, in addition to fractional crystallization, some of the

  15. Genesis of the Bangbule Pb-Zn-Cu polymetallic deposit in Tibet, western China: Evidence from zircon U-Pb geochronology and S-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Kan, Tian; Zheng, Youye; Gao, Shunbao

    2016-04-01

    The Banbule Pb-Zn-Cu skarn deposit is located in the Longger-Gongbujiangda volcanic magma arc in the Gangdese-Nyainqentanglha Plate. It is the only lead-zinc polymetallic deposit discovered in the westernmost Nyainqentanglha metallogenic belt. The measured and indicated resources include 0.9 Mt of Pb+Zn (4.77% Pb and 4.74% Zn, respectively), 6499 t of Cu, and 178 t of Ag (18.75g/t Ag). The orebodies mainly occur as lenses, veins and irregular shapes in the contact zone between the quartz-porphyry and limestone of the Upper Permian Xiala Formation, or in the boundaries between limestone and sandstone. Pb-Zn-Cu mineralization in the Banbule deposit is closely associated with skarns. The ore minerals are dominated by galena, sphalerite, chalcopyrite, bornite, and magnetite, with subordinate pyrite, malachite, and azurite. The gangue minerals are mainly garnet, actinolite, diopside, quartz, and calcite. The ore-related quartz-porphyry displays LA-ICP-MS zircon U-Pb age of 77.31±0.74 Ma. The δ34S values of sulfides define a narrow range of -0.8 to 4.7‰ indicating a magmatic source for the ore-forming materials. Lead isotopic systematics yield 206Pb/204Pb of 18.698 to 18.752, 207Pb/204Pb of 15.696 to 15.760, and 208Pb/204Pb of 39.097 to 39.320. The data points are constrained around the growth curves of upper crust and orogenic belt according to the tectonic discrimination diagrams. The calculated Δβ - Δγ values plot within the magmatic field according to the discrimination diagram of Zhu et al. (1995). The S-Pb isotopic data suggest that Bangbule is a typical skarn deposit, and the Pb-Zn-Cu mineralization is genetically related to the quartz-porphyry in the mining district. The discovery of the Bangbule deposit indicates that there is metallogenic potential in the westernmost Nyainqentanglha belt, which is of great importance for the exploration work in this area.

  16. Heavy metal input to agricultural soils from irrigation with treated wastewater: Insight from Pb isotopes

    NASA Astrophysics Data System (ADS)

    Kloppmann, Wolfram; Cary, Lise; Psarras, Georgios; Surdyk, Nicolas; Chartzoulakis, Kostas; Pettenati, Marie; Maton, Laure

    2010-05-01

    A major objective of the EU FP6 project SAFIR was to overcome certain drawbacks of wastewater reuse through the development of a new irrigation technology combining small-scale modular water treatment plants on farm level and improved irrigation hardware, in the aim to lower the risks related to low quality water and to increase water use efficiency. This innovative technology was tested in several hydro-climatic contexts (Crete, Italy, Serbia, China) on experimental irrigated tomato and potato fields. Here we present the heavy metal variations in soil after medium-term (3 irrigation seasons from 2006-2008) use of treated municipal wastewater with a special focus on lead and lead isotope signatures. The experimental site is located in Chania, Crete. A matrix of plots were irrigated, combining different water qualities (secondary, primary treated wastewater, tap water, partially spiked with heavy metals, going through newly developed tertiary treatment systems) with different irrigation strategies (surface and subsurface drip irrigation combined with full irrigation and partial root drying). In order to assess small scale heavy metal distribution around a drip emitter, Pb isotope tracing was used, combined with selective extraction. The sampling for Pb isotope fingerprinting was performed after the 3rd season of ww-irrigation on a lateral profile from a drip irrigator (half distance between drip lines, i.e. 50cm) and three depth intervals (0-10, 10-20, 20-40 cm). These samples were lixiviated through a 3 step selective extraction procedure giving rise to the bio-accessible, mobile and residual fraction: CaCl2/NaNO3 (bio-accessible fraction), DPTA (mobile fraction), total acid attack (residual fraction). Those samples were analysed for trace elements (including heavy metals) and major inorganic compounds by ICP-MS. The extracted fractions were then analysed by Thermal Ionisation Mass Spectrometry (TIMS) for their lead isotope fingerprints (204Pb, 206Pb, 207Pb, 208Pb

  17. Genesis of the Bangbule Pb-Zn-Cu polymetallic deposit in Tibet, western China: Evidence from zircon U-Pb geochronology and S-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Kan, Tian; Zheng, Youye; Gao, Shunbao

    2016-04-01

    The Banbule Pb-Zn-Cu skarn deposit is located in the Longger-Gongbujiangda volcanic magma arc in the Gangdese-Nyainqentanglha Plate. It is the only lead-zinc polymetallic deposit discovered in the westernmost Nyainqentanglha metallogenic belt. The measured and indicated resources include 0.9 Mt of Pb+Zn (4.77% Pb and 4.74% Zn, respectively), 6499 t of Cu, and 178 t of Ag (18.75g/t Ag). The orebodies mainly occur as lenses, veins and irregular shapes in the contact zone between the quartz-porphyry and limestone of the Upper Permian Xiala Formation, or in the boundaries between limestone and sandstone. Pb-Zn-Cu mineralization in the Banbule deposit is closely associated with skarns. The ore minerals are dominated by galena, sphalerite, chalcopyrite, bornite, and magnetite, with subordinate pyrite, malachite, and azurite. The gangue minerals are mainly garnet, actinolite, diopside, quartz, and calcite. The ore-related quartz-porphyry displays LA-ICP-MS zircon U-Pb age of 77.31±0.74 Ma. The δ34S values of sulfides define a narrow range of -0.8 to 4.7‰ indicating a magmatic source for the ore-forming materials. Lead isotopic systematics yield 206Pb/204Pb of 18.698 to 18.752, 207Pb/204Pb of 15.696 to 15.760, and 208Pb/204Pb of 39.097 to 39.320. The data points are constrained around the growth curves of upper crust and orogenic belt according to the tectonic discrimination diagrams. The calculated Δβ ‑ Δγ values plot within the magmatic field according to the discrimination diagram of Zhu et al. (1995). The S-Pb isotopic data suggest that Bangbule is a typical skarn deposit, and the Pb-Zn-Cu mineralization is genetically related to the quartz-porphyry in the mining district. The discovery of the Bangbule deposit indicates that there is metallogenic potential in the westernmost Nyainqentanglha belt, which is of great importance for the exploration work in this area.

  18. Magmas with slab fluid and decompression melting signatures coexisting in the Gulf of Fonseca: Evidence from Isla El Tigre volcano (Honduras, Central America)

    NASA Astrophysics Data System (ADS)

    Mattioli, Michele; Renzulli, Alberto; Agostini, Samuele; Lucidi, Roberto

    2016-01-01

    Isla El Tigre volcano is located in the Gulf of Fonseca (Honduras) along the Central America volcanic front, where a significant change in the strike of the volcanic chain is observed. The studied samples of this poorly investigated volcano are mainly subalkaline basic to intermediate lavas (basalts and basaltic andesites) and subordinate subalkaline/alkaline transitional basalts, both having the typical mineralogical and geochemical characteristics of arc volcanic rocks. On the basis of petrographic and geochemical features, two groups of rocks have been distinguished. Lavas from the main volcanic edifice are highly porphyritic and hy-qz normative, and have lower MgO contents (< 5 wt.%). They show significant LILE and LREE enrichments and Nb-Ta depletions, and have a strong slab signature as well as incompatible element contents similar to those of the main front of the adjacent volcanoes in El Salvador and Nicaragua (e.g., Ba/La up to 80). In contrast, lavas from the parasitic cones have higher MgO contents (> 5 wt.%), are ol-hy normative and show lower HFSE depletions relative to LILE and LREE, with lower Ba/La, Ba/Nb and Zr/Nb ratios. This suggests that mantle-derived magmas were not produced by the same process throughout the activity of the volcano. The bulk rock geochemistry and 87Sr/86Sr (0.70373-0.70382), 143Nd/144Nd (0.51298-0.51301), 206Pb/204Pb (18.55-18.58), 207Pb/204Pb (15.54-15.56) and 208Pb/204Pb (38.23-38.26) isotopic data of Isla El Tigre compared with the other volcanoes of the Gulf of Fonseca and all available literature data for Central America suggests that this stratovolcano was mainly built by mantle-derived melts driven by slab-derived fluid-flux melting, while magmas erupted through its parasitic cones have a clear signature of decompression melting with minor slab contribution. The coexistence of these two different mantle melting generation processes is likely related to the complex geodynamic setting of the Gulf of Fonseca, where the

  19. Petrogenesis of the Yaochong granite and Mo deposit, Western Dabie orogen, eastern-central China: Constraints from zircon U-Pb and molybdenite Re-Os ages, whole-rock geochemistry and Sr-Nd-Pb-Hf isotopes

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Xu, Zhaowen; Qiu, Wenhong; Li, Chao; Yu, Yang; Wang, Hao; Su, Yang

    2015-05-01

    The Dabie orogen is among the most famous continent-continent collisional orogenic belts in the world, and is characterized by intensive post-collisional extension, magmatism and Mo mineralization. However, the genetic links between the mineralization and the geodynamic evolution of the orogen remain unresolved. In this paper, the Yaochong Mo deposit and its associated granitic stocks were investigated to elucidate this issue. Our new zircon U-Pb ages yielded an Early Cretaceous age (133.3 ± 1.3 Ma) for the Yaochong granite, and our molybdenite Re-Os dating gave a similar age (135 ± 1 Ma) for the Mo deposit. The Yaochong stock is characterized by high silica and alkali but low Mg, Fe and Ca. It is enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs: Rb, K, Th and U), but strongly depleted in heavy REEs, and high field strength elements (HFSEs: Nb, Ta, Ti and Y). The Yaochong granite has initial 87Sr/86Sr ratios of 0.7087-0.7096, and Pb isotopic ratios of (206Pb/204Pb)i = 16.599-16.704, (207Pb/204Pb)i = 15.170-15.618 and (208Pb/204Pb)i = 36.376-38.248. The granite has εNd(t) of -18.0 to -16.3 and εHf(t) values of -26.5 to -20.0. All these data indicate that the Yaochong granite is a high-K calc-alkaline fractionated I-type granite, and may have originated from partial melting of the thickened Yangtze continental crust. The Mo ores also show low radiogenic Pb isotopes similar to the Yaochong stock. Medium Re content in molybdenite (21.8-74.8 ppm) also suggests that the ore-forming materials were derived from the thickened lower crust with possibly minor mixing with the mantle. Similar to the Eastern Dabie orogen, the thickened crust beneath the Western Dabie orogen may also have experienced tectonic collapse, which may have exerted fundamental geodynamic controls on the two-stage Mo mineralization in the region.

  20. A Coordinated Research Project on the Implementation of Nuclear Techniques to Improve Food Traceability

    NASA Astrophysics Data System (ADS)

    Frew, Russell; Cannavan, Andrew; Zandric, Zora; Maestroni, Britt; Abrahim, Aiman

    2013-04-01

    coffee, the adulteration of milk with soy protein, chemical contamination of food products, and inhomogeneity in isotopic ratios in poultry and eggs as a means to determine production history. Analytical techniques include stable isotope ratio measurements (2H/1H, 13C/12C, 15N/14N, 18O/16O, 34S/32S, 87Sr/86Sr, 208Pb/207Pb/206Pb), elemental analysis, DNA fingerprinting, fatty acid and other biomolecule profiling, chromatography-mass spectrometry and near infra-red spectroscopy.

  1. Nd, Pb and Sr isotopic data from the Mount Elgon volcano, eastern Uganda-western Kenya: Implications for the origin and evolution of nephelinite lavas

    NASA Astrophysics Data System (ADS)

    Simonetti, A.; Bell, K.

    1995-11-01

    Nd, Pb and Sr isotope ratios for nephelinites from the Tertiary Mount Elgon alkaline volcanic centre, eastern Uganda-western Kenya, are highly variable and indicate open system behaviour. The variation in {143Nd }/{144Nd } (0.51219-0.51286) and {87Sr }/{86Sr } (0.70314-0.70604) ratios span almost the entire range documented for carbonatites from several East African alkaline complexes. The whole rock chemical data, mineralogy, composition of diopside phenocrysts, and variation in isotopic ratios from the Mount Elgon nephelinites are similar to those from the nephelinite lavas from the Tertiary Napak volcano, Uganda (Simonetti and Bell, 1994a). The diopside phenocrysts from Mount Elgon nephelinite lavas reveal large core-to-rim compositional variations (which include normal, oscillatory and reverse zoning), and their Nd, Pb and Sr isotopic ratios are not in isotopic equilibrium with their host lavas. Microprobe data along with textural evidence from the Mount Elgon diopside phenocrysts support a model that involves crystallization in an open magma system that was undergoing continuous chemical and isotopic change. The large variation in Pb isotopic ratios (whole rocks- {206Pb }/{204Pb }: 18.45-21.51; {207Pb }/{204Pb }: 15.61-15.88; {208Pb }/{204Pb }: 38.62-41.02), from the Mount Elgon lavas, best fit a model involving mixing between EM I and HIMU mantle components, and correlations in Pb-Sr and Pb-Nd isotopic plots partly support this interpretation. The isotopic data from Mount Elgon and Napak nephelinites suggest complex evolutionary histories involving magma mixing, and support the presence of a heterogeneous sub-continental source beneath eastern Uganda, similar to that documented for various types of peralkaline nephelinite lavas from the only active carbonatite-nephelinite volcano, Oldoinyo Lengai, Tanzania (Bell and Dawson, 1995) and other East African volcanoes (e.g. Vollmer and Norry, 1983). The chemical data and large variation in isotopic ratios for the

  2. Magma source components in an arc-continent collision zone: the Flores-Lembata sector, Sunda arc, Indonesia

    NASA Astrophysics Data System (ADS)

    Stolz, A. J.; Varne, R.; Davies, G. R.; Wheller, G. E.; Foden, J. D.

    1990-10-01

    Major, trace-element, and Sr-, Nd-and Pbisotope data are presented for volcanics from 12 active or recently active volcanoes from the islands of Flores, Adonara, Lembata and Batu Tara in the eastern Sunda are. The volcanics vary in composition from low-K tholeiite, through medium-and high-K calcalkaline types to the K-rich leucite basanites of Batu Tara. From the tholeiites to the leucite basanites there are marked increases in the concentrations of LILE (K, Rb, Ba, Sr), LREE and La/Yb, and all the volcanics have high Ba/ Nb, La/Nb and Ba/La compared with mid-ocean ridge and intraplate eruptives. K/Cs values are generally lower than OIB values, and overlap those of other arc volcanics and northeast Indian Ocean sediments. The volcanics exhibit a broad range of 87Sr/86Sr (0.70468 0.70706), 143Nd/144Nd (0.512946 0.512447), and a moderate range in 206Pb/204Pb (18.825 19.143), 207Pb/ 204Pb (15.643 15.760) and 208Pb/204Pb (38.97 39.51). Trace-element and isotopic data suggest that the mantle beneath the eastern Sunda arc is a complex heterogeneous mixture of 3 or 4 major source components: MORB-source or depleted MORB-source, OIB-source and subducted Indian Ocean sediment. The low-K tholeiites were probably formed by relatively large degrees of melting of depleted MORB-source mantle, modified by subduction-related fluids, whereas the trace-element and isotopic characteristics of the K-rich volcanics suggest that they were derived from an OIB source which and been modified by a subduction-related melt component. The source components of the medium-to high-K calcalkaline rocks are more difficult to determine, and probably include mixtures of MORB-source or OIB-source, and melt/fluid derived from subducted oceanic sediment. Minor-and trace-element modelling calculations indicate substantial difficulties in producing the relatively low Ti-contents of arc volcanics by melting OIB-source mantle. Where OIB mantle is considered to be an important component of arc magmas it is

  3. Geochronology and geochemistry of Eocene potassic felsic intrusions in the Nangqian basin, eastern Tibet: Tectonic and metallogenic implications

    NASA Astrophysics Data System (ADS)

    Xu, Yue; Bi, Xian-Wu; Hu, Rui-Zhong; Chen, You-wei; Liu, He-qing; Xu, Lei-luo

    2016-03-01

    The Jinshajiang-Ailaoshan copper belt is the most significant porphyry copper belt in eastern Tibet. In the northern segment of this belt within the Nangqian basin, which occurs 100 km east of the Yulong porphyry copper deposit, several felsic intrusions have been recently discovered. The Yulong porphyry copper deposit is one of the largest porphyry copper deposits in China, and it is associated with peraluminous adakitic rocks formed in a post-collisional setting. The Nangqian felsic intrusions vary from syenite porphyry to monzonite porphyry in rock types. No significant Cu-Au mineralization has been found in the Nangqian felsic intrusions despite extensive exploration in recent years. LA-ICP-MS zircon U-Pb dating reveals that the Nangqian syenite porphyry and monzonite porphyry were emplaced at ~ 35.6±0.3 Ma and from 39.5±0.3 to 37.4±0.3 Ma, respectively, similar to the age of the Yulong porphyry copper deposit. The Nangqian felsic intrusions are characterized by metaluminous compositions (A/CNK = 0.82-1.01), and they share some common features with shoshonites such as high K2O contents (4.58-5.58 wt.%), high K2O/Na2O ratios (0.92-1.28), LREE-LILE enrichments and negative Nb-Ta-Ti-P anomalies, as well as with adakites derived from an eclogite-facies source with high Al2O3 (14.98-15.74 wt.%), Sr (954-2190 ppm), Sr/Y (68-132) and La/Yb (53-85), and low Y and Yb contents. The Nangqian felsic intrusions have high initial 87Sr/86Sr (0.7050-0.7055), variable εNd(t) (- 0.31-1.43) and small variations in (206Pb/204Pb)i (18.68-18.74), (207Pb/204Pb)i (15.53-15.62) and (208Pb/204Pb)i (38.51-38.80). Zircon crystals from both syenite and monzonite porphyries are characterized by positive εHf(t) from 5.2 to 8.5. The results suggest that the syenite and monzonite magmas were differentiated from parental shoshonitic melts by fractional crystallization of olivine, clinopyroxene and minor feldspar. The parent magmas originated from a lithospheric mantle metasomatized by slab

  4. Zircon U-Pb dating, geochemistry and Sr-Nd-Pb-Hf isotopes of the Wajilitag alkali mafic dikes, and associated diorite and syenitic rocks: Implications for magmatic evolution of the Tarim large igneous province

    NASA Astrophysics Data System (ADS)

    Zou, Si-Yuan; Li, Zi-Long; Song, Biao; Ernst, Richard E.; Li, Yin-Qi; Ren, Zhong-Yuan; Yang, Shu-Feng; Chen, Han-Lin; Xu, Yi-Gang; Song, Xie-Yan

    2015-01-01

    The Early Permian Tarim large igneous province (Tarim LIP) consists mainly of basaltic lavas, mafic-ultramafic intrusions including dikes and, syenite bodies in the Tarim Basin, NW China. A major unit of the Tarim LIP, the Wajilitag intrusive complex, consists of olivine pyroxenite, clinopyroxenite and gabbro units (from bottom to top), diorite and syenite rocks occurred in the upper part of the complex and alkali mafic dikes intrude the clinopyroxenite phase. Here we report the zircon U-Pb age and Hf isotopes, geochemical characteristics and Sr-Nd-Pb isotopic data of the alkali mafic dikes, and diorite, aegirine-nepheline syenite and syenite porphyry units in the Wajilitag intrusive complex. Zircons from the diorite and alkali mafic rocks yield concordant crystallization ages of 275.2 ± 1.2 Ma and 281.4 ± 1.7 Ma, respectively. The diorite and syenitic rocks in Wajilitag area have a narrow range of SiO2 contents (51.9-57.3 wt.%), and are enriched in total alkalis (Na2O + K2O = 8.3-14.3 wt.%), among which the aegirine-nepheline syenite and syenite porphyry have the geochemical affinity of A-type granites. The alkali mafic rocks and syenitic rocks have high Al2O3 (19.4-21.1 wt.%), Zr, Hf, Ba contents, total rare earth element abundances and LREE/HREE ratios and low Mg# value, K, P and Ti contents. Diorites have lower Al2O3 contents, total REE abundances and LREE/HREE ratios and higher Mg# values than the alkali mafic rocks and syenitic rocks. The diorites and syenitic rocks have low initial 87Sr/86Sr ratios (0.7034-0.7046), and high εNd(t) values (0.1-4.1) and zircon εHf(t) values (- 0.9-4.4). All the diorites and syenitic rocks show the 206Pb/204Pb ratios ranging of 18.0-19.5, 207Pb/204Pb of 15.4-15.6 and 208Pb/204Pb of 38.0-39.9. Sr-Nd isotopic ratios indicate a FOZO-like mantle source for the diorite and syenitic rocks, similar to that of the mafic-ultramafic rocks in the Wajilitag complex. In contrast, zircon Hf isotopes of basalt and syenite elsewhere in the

  5. Geological, fluid inclusion and isotopic studies of the Baiyangping Pb-Zn-Cu-Ag polymetallic deposit, Lanping basin, Yunnan province, China

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Hu; Hou, Zeng-Qian; Song, Yu-Cai; Zhang, Hong-Rui

    2015-11-01

    Baiyangping Pb-Zn-Cu-Ag deposit is located in Lanping basin, northwestern Yunnan province. The deposit is composed of a few ore veins and can be divided into several ore blocks. The ore bodies are primarily hosted in Mesozoic carbonate, sandstone and siltstone along the north-south-striking, NWW-striking and NE-SW-striking fault zones. There are breccia, massive, vein like and disseminated ores. The main ore minerals are sphalerite, galena, gratonite, jordanite, tetrahedrite series minerals, chalcocite, chalcopyrite, realgar, orpiment, bournonite, cobalt-bearing arsenopyrite, argentite, kongsbergite, cobaltine, siegenite. The sizes of fluid inclusions in Baiyangping deposit are generally less than 10 μm and have the shape of round, oval, irregular, etc. The ore-forming fluid system is Ca2+-Na+-K+-Mg2+-Cl--F--NO3- brine system. The freezing temperature of fluid inclusions in mineral deposits ranges from -26.4 to -0.2 °C, average -14.6 °C; the homogenization temperature is concentrated in 120-180 °C, and the salinity is between 0.35 and 24.73 wt% (NaCleq), average 16.9 wt% (NaCleq). δ13CPDB and δ18OSMOW values of hydrothermal calcite range from -4.16‰ to 3‰ and -2.5‰ to 20.4‰, respectively. δ34S values of sulfide minerals range from -10.2‰ to 11.2‰, average 5.6‰. The sulfide samples yield 206Pb/204Pb values of 18.609-18.818, 207Pb/204Pb of 15.548-15.842 and 208Pb/204Pb = 38.514-39.556. C-O-S-Pb isotope compositions of the Baiyangping deposit indicate a homogeneous carbon source, and the carbon in hydrothermal calcite is derived from the dissolution of carbonate rock strata, the ore-forming fluid belongs to basin brine fluid system, which is mixed with the precipitate water, sulfur in sulfides and sulfosalts is derived from thermal chemical sulfate reduction, and the thermal decomposition of sulfur-bearing organic matter. The metal mineralization material is from sedimentary strata and basement. The late Pb-Zn polymetallic mineralization event

  6. Sm-Nd dating and REE Composition of scheelite for the Honghuaerji scheelite deposit, Inner Mongolia, Northeast China

    NASA Astrophysics Data System (ADS)

    Guo, Zhijun; Li, Jinwen; Xu, Xinying; Song, Zeyou; Dong, Xuzhou; Tian, Jing; Yang, Yuncheng; She, Hongquan; Xiang, Anping; Kang, Yongjian

    2016-09-01

    Sm-Nd analyses of seven scheelite samples from scheelite-quartz veins in the Honghuaerji scheelite deposit produce a well-defined linear array on an isochron diagram with a mean square weighted deviation (MSWD) of 0.87 corresponding to an age of 178.4 ± 2.9 Ma with εNd(t) = + 1.50. This age is interpreted to represent the age of scheelite mineralization. The scheelite Sm-Nd age is in good agreement with U-Pb ages obtained from a mineralization-related granite (179.4 ~ 178.6 Ma), indicating that there is no apparent age gap between granite crystallization and ore formation. Rare earth element (REE) abundances in the scheelite were determined by in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and the scheelite samples contain elevated REE concentrations with total ΣREE + Y contents in the range of 3339 to 6321 ppm. The chondrite-normalized REE distribution patterns of all scheelites are middle REE (MREE)-enriched, with strong negative Eu-anomalies (Eu/Eu* = 0.09 ~ 0.23). The REE characteristics of the Honghuaerji scheelite suggest that REE3 + substituted into the Ca site along with Na and Nb (dominated by Na), whereas Eu is predominantly present as Eu2 + in the scheelite and may have crystallized from relatively reduced fluids. All sulfur isotope data (δ34S) for sulfide separates range from + 2.0 to + 3.8‰, with an average of 3.2‰. Measured 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios vary from 18.243 to 18.451, 15.494 to 15.574, and 37.933 to 38.340, respectively. On the basis of common Sr-Nd-Pb-Hf isotopic characteristics between the scheelite and the host granite and the positive initial Nd isotope ratios (+ 1.46 - + 1.52), low 87Sr/86Sr ratios (0.704983-0.705297) in the scheelites, it is inferred that the hydrothermal fluids responsible for tungsten mineralization at Honghuaerji were of magmatic origin with a mantle-derived signature. Based on the regional geology, tectonic evolution, and geochemical evidence, the

  7. A Coast Mountains provenance for the Valdez and Orca groups, southern Alaska, based on Nd, Sr, and Pb isotopic evidence

    USGS Publications Warehouse

    Farmer, G.L.; Ayuso, R.; Plafker, G.

    1993-01-01

    Nd, Sr, and Pb isotopic data were obtained for fourteen fine- to coarse-grained samples of accreted flysch of the Late Cretaceous and early Tertiary Valdez and Orca Groups in southern Alaska to determine the flysch provenance. Argillites and greywackes from the Orca Group, as well as compositionally similar but higher metamorphic grade rocks from the Valdez Group, show a restricted range of correlated ??{lunate}Nd ( -0.6 to -3.8) and 87Sr 86Sr (0.7060-0.7080) at the time of sediment deposition ( ??? 50 Ma). Pb isotopic compositions also vary over a narrow range ( 206Pb 204Pb = 19.138-19.395, 207Pb 204Pb = 15.593-15.703, 208Pb 204Pb = 38.677-39.209), and in the Orca Group the samples generally become more radiogenic with decreasing ??{lunate}Nd and increasing 87Sr 86Sr. All samples have similar trace element compositions characterized by moderate light rare earth element enrichments, and low ratios of high field strength elements to large ion lithophile elements. Based on petrographic, geochemical, and isotopic data the sedimentary rocks are interpreted to have been derived largely from a Phanerozoic continental margin arc complex characterized by igneous rocks with ??{lunate}Nd values between 0 and -5. The latter conclusion is supported by the ??{lunate}Nd values of a tonalite clast and a rhyodacite clast in the Orca Group (??{lunate}Nd = -4.9 and -0.9, respectively). However, trondjemitic clasts in the Orca Group have significantly lower ??{lunate}Nd ( ??? -10) and require a derivation of a portion of the flysch from Precambrian crustal sources. The Nd, Sr, and Pb isotopic compositions of both the Valdez and Orca Groups overlap the values determined for intrusive igneous rocks exposed within the northern portion of the Late Cretaceous to early Tertiary Coast Mountains Plutonic Complex in western British Columbia and equivalent rocks in southeastern Alaska. The isotopic data support previous conclusions based on geologic studies which suggest that the flysch was

  8. New insights into the petrogenesis of volcanic rocks in the Shanghang Basin in the Fujian Province, China

    NASA Astrophysics Data System (ADS)

    Jiang, Si-Hong; Bagas, Leon; Liang, Qing-Ling

    2015-06-01

    The Mesozoic Shanghang Basin in southeastern China consists of Early Cretaceous mottled coarse-grained clastic and volcanic rocks, and Late Cretaceous clastic rocks. The volcanic rocks are intermediate-mafic to felsic and spatially close to the famous Zijinshan Mineral Field. In order to better understand the timing, petrogenesis and tectonic setting of these volcanic rocks and the relationship between magmatism and metallogeny in the mineral field, U-Pb zircon geochronological, geochemical and Sr-Nd-Pb-Hf isotopic studies were completed on the volcanic rocks. Fifteen LA-MC-ICP-MS U-Pb zircon analyses of the volcanic rocks yield weighted mean ages of between 105 and 99 Ma. Major and trace element geochemistry shows that these rocks are mostly high-K to shoshonitic, enriched in LREE and Th, U, and depleted in Ba, Nb, Sr, P and Ti. The volcanic rocks have 87Sr/86Sri ratios of between 0.70732 and 0.70977, 206Pb/204Pb isotope ratios of 18.57-19.77, 207Pb/204Pb isotope ratios of 15.64-15.71, 208Pb/204Pb isotope ratios of 38.87-40.62, 176Hf/177Hf ratios of 0.282589-0.282823, εNdT values of -7.5 to -4.7, and εHf(t) values of -4.2 to 4. Such characteristics, with similarities to coeval volcanic and intrusive rocks adjacent to the basin, suggest that the parent magma of the Cretaceous volcanic rocks in the basin and their contemporaneous intrusives originated from crustal melts with a juvenile component. Petrogenetically, fractional crystallization with minor wall-rock assimilation is the controlling process in deriving a wide range of more evolved rocks. With reference to the ore-forming events and isotopic features of ore-related intrusions in the Zijinshan Mineral Field, we propose that volcanism in the Shanghang Basin and coeval magmatism in the mineral field are related to the formation of the regional porphyry and epithermal Cu-Au-Mo-Ag deposits in an extension tectonic setting related to the subduction of the Paleo-Pacific Plate.