O objetivo deste trabalho foi o de otimizar a adição de estrôncio em liga A356 visando obter as melhores propriedades mecânicas de ductilidade. Foram estudados diferentes níveis de adição de estrôncio em ligas A356 com dois níveis de fósforo residual. Além disto, foi estudado o efeito de adições crescentes de magnésio na morfologia do silício em liga Al-7%Si modificada. Para a realização deste estudo, foram produzidos corpos de prova de tração segundo ASTM B108 com velocidade de resfriamento de 8°C/s. Os corpos de prova foram endurecidos por precipitação via tratamento térmico e tracionados. Além de uma avaliação quantitativa das propriedades mecânicas, amostras de todas as condições passaram por uma avaliação metalográfica qualitativa. Foi feito também ataque profundo para observação das morfologias das partículas de silício em microscópio eletrônico. O efeito da adição crescente de estrôncio na liga A356 em um intervalo de 0 a 256 ppm de estrôncio foi o de aumento do alongamento até teores de 50 a 60 ppm, seguido de uma diminuição do mesmo até 256 ppm. O teste de adição crescente de estrôncio foi repetido para uma liga A356 com teor residual de fósforo de aproximadamente 10 ppm. A curva de alongamento segue o mesmo formato da curva levantada para amostras que não continham fósforo, embora tenha sido encontrada uma sensível queda nos valores de alongamento na presença de fósforo. A presença de magnésio em ligas Al-Si modificadas por estrôncio foi responsável por uma mudança na morfologia de crescimento das partículas de silício nas regiões de contornos de células eutéticas, além do aparecimento de partículas intermetálicas nesta mesma região. Deste trabalho, concluiu-se que as melhores propriedades mecânicas de ductilidade foram obtidas para a adição de estrôncio de 50 a 60 ppm. / This work has, as its main objective, the optimization of the strontium addition in A356 alloy, in order to obtain the best ductility results. The addition of several different strontium amounts in alloys containing two phosphorous amounts was studied. Besides, the effect of increasing magnesium content on the morphology of the silicon particles of Al-7%Si modified alloy was also studied. Test bars were produced from ASTM B108 cooled at a rate of 8°C/s. The samples were heat treated and then tested. The mechanical properties were evaluated and the microstructures were analyzed. The silicon morphology was observed in deep etched samples at SEM. Strontium additions of 0 to 256 ppm increased the elongation up to 50-60 ppm. Above 75 ppm, the addition of strontium caused the elongation to decrease up to 256 ppm. The same test was reproduced for an alloy containing approximately 10 ppm P and, although the best results were achieved at strontium additions of 50-60 ppm, the elongation results were clearly lower. The presence of magnesium in Al-7%Si modified alloys was responsible for a change in the growth morphology of the silicon particles, especially near grain boundaries, and also for the formation of intermetallic particles in those areas. From this work, it was possible to conclude that the best ductility properties are achieved for strontium additions of 50-60 ppm.

Neste trabalho é apresentado o potencial de remoção de íons estrôncio de soluções aquosas pelas fibras de coco na forma bruta e na forma ativada com peróxido de hidrogênio, 1% e 4%, em meio básico. Os experimentos de biossorção foram realizados em batelada com 2 mg.L-1 de solução de Sr(NO3)2 e foram estudadas as influências dos seguintes parâmetros: tempo de contato, pH e a eficiência de biossorção das fibras ativadas em comparação com a fibra de coco bruta (FCB). A caracterização das fibras antes e após o tratamento, e a presença de Sr2+ nas fibras foram realizadas por microscopia de varredura eletrônica com detector de espectroscopia de energia dispersiva, espectroscopia de difração de raios X, espectroscopia de infravermelho e por análise térmica. Dentre as fibras estudadas, a fibra de coco ativada com 1% H2O2 (FCA 1) apresentou a maior capacidade de biossorção: 3,6 mg.g-1, nas seguintes condições: 5 mg de biomassa em pH 6, após 90 minutos de tempo de contato à temperatura ambiente. A fibra de coco ativada com 4% H2O2 (FCA 2) levou a uma maior degradação dos constituintes da fibra e consequentemente a uma menor remoção de íons de Sr2+.Para os estudos de modelos de isotermas de biossorção de Sr2+, tanto a FCB quanto a FCA 1 ajustaram-se melhor ao modelo de Langmuir e à cinética de pseudo-segunda ordem. Os parâmetros termodinâmicos energia livre de Gibbs (ΔG) e coeficiente de distribuição (KD) foram -0,90 kJ.mol-1 e 265,3L.Kg-1 para a FCB e de -7,2 kJ.mol-1 e 824,3 L.Kg-1 para a FCA1. Esses resultados demonstraram que a FCA 1 possui uma boa eficiência para remover íons de Sr2+de resíduos químicos aquosos e é uma boa alternativa no tratamento de rejeitos radioativos líquidos contendo íons 90Sr. / This work presents the potential of strontium ions removal from aqueous solutions using coconut fiber in raw and treated form with hydrogen peroxide, 1% and 4%, in alkaline conditions. The biosorption experiments were performed in batch mode with 2 mg.L-1 solution of Sr(NO3)2 and the influence of the following parameters were studied: contact time and pH. It was also evaluate the biosorption efficiency of the treated coconut fibers in comparison with the raw coconut fiber (RCF). The fibers characterizations before and after treatment and the presence of the Sr2+ in the fibers were performed by scanning electron microscopy with a detector energy dispersive spectroscopy, diffraction of x-ray spectroscopy, infrared spectroscopy and thermal analysis. Among the studied fibers, the treated coconut fiber with 1% of H2O2 (TCF 1) showed the major biosorption capacity of 3.6 mg.g-1 in the following conditions: 5 mg of biomass at pH 6, 90 minutes of contact time at room temperature. Treated coconut fiber with 4% H2O2 (TCF 2) showed the lowest Sr2+ ions removal due to degradation of the fibers constituents. For studies of biosorption isotherms, both raw and treated coconut fiber (TCF 1) were fitted better to Langmuir model and the kinetics reaction was of pseudo-second order. The thermodynamic parameters Gibbs free energy (ΔG) and distribution coefficient (KD) were -0.90 kJ.mol-1 and 265.3 L.Kg-1 for RCF and of -7,2 kJ.mol-1 and 824.3L.Kg-1 for TCF 1. These results demonstrated that the TCF 1 has good efficiency for removing Sr2+ ions in the aqueous chemical waste and is a good alternative in treatment of liquid radioactive wastes containing 90Sr.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016. / Radiostrontium (90Sr and 89Sr) has been released to the environment by global fall-out following atmospheric nuclear explosions, by waste discharges and fall-out from the Chernobyl. 89Sr, with a half-life of 50.5 days, quickly decays to undetectable levels, while 90Sr is radiobiologically more important because of its longer half-life of 28.78 years, and because it behaves chemically similar to Ca, and accumulates in bones and teeth. Cost effective and relatively simple procedures for determination of radiostrontium are desirable. An accurate determination of radionuclides from various sources in the environment is essential for assessment of the potential hazards and suitable countermeasures both in case of accidents, authorised releases and routine surveillances. Reliable radiochemical separation and detection techniques are needed for accurate determination of alpha and beta emitters. Rapid analytical methods are needed in case of an accident for early decision-making. At the Koeberg Nuclear Power Station (KNPS), 90Sr analysis are performed on liquid effluent samples making use of the traditional fuming nitric acid method, and subsequent counting of particulate samples on an alpha/beta proportional counter. This method is often at times very time – consuming, and involves many precipitation steps. The use of fuming nitric acid is also very dangerous and could lead to severe personnel injuries in the event of an accident. This project focussed on the application of Sr-Spec resin in the analysis of 90Sr. This work presents the methods for 90Sr analysis for both effluent samples as well as environmental samples. This research also focussed on the calibration of the different radiometric instruments, which are the Liquid Scintillation Counter, the Alpha/Beta Counter as well as the Gamma Detector.

The timing of glacial-interglacial cycles shows a clear dependence on the periodic variations in the Earth’s orbital parameters. However, the Earth’s climate is an extremely complex, non-linear system, with many internal feedback mechanisms and there are still features of the climate record for which a definitive explanation remains elusive. Understanding reef history is important due to significant predicted feedbacks between changes in global climate and carbonate production via the carbon cycle; phases of rapid reef growth in shallow water areas being associated with increased release of carbon dioxide to the atmosphere. Previous work on Pleistocene reef history, investigated via reef boreholes, shows a large global expansion of reefs between 800-400ka; approximately concurrent with one of the major unexplained alterations in the climate system, the Mid-Pleistocene Transition (MPT). Quaternary reef history is usually investigated via reef boreholes, which provide limited spatial information and are subject to dating uncertainties of the order of ±100kyrs. This means that any inferences made about the relationship between reef expansion and specific changes in the climate system are not well constrained. This thesis instead, presents a novel approach to reconstructing reef growth history, using a trial site near the island of New Caledonia, in the south west Pacific. The initiation of carbonate production on shallow shelves is known to produce a signal in the surrounding deeper basins, via sediment shedding. Therefore, this research set out to independently verify the proposed expansion of the New Caledonia Barrier Reef at ~ 400ka (Marine Isotope Stage [MIS] 11) by examining the composition of turbidites deposited in the New Caledonia Trough. Deep sea sediment core MD06-3019, was collected south west of the New Caledonia Barrier Reef (22oS, 165oE; 3,500m water depth). It is predominantly composed of pelagic carbonate ooze, into which 79 sandy turbidite layers have been deposited. These layers interrupt, but do not disturb, the background sedimentation and source material from the shallow shelf, which is carried to the deep sea via submarine canyons. A core age model based principally on orbital tuning, yields a core bottom age of 1,260ka, ~MIS38. This chronology has allowed the timing of deposition of the turbidite layers within the core to be assigned to within ±10kyr. Turbidite layers vary in width (1-35cm), grain size (φ=4 to -2) and composition, containing among other shelf derived material, well preserved coral fragments from 1.26Ma through to the present day. Patterns in turbidite timing and frequency, grain size and composition (investigated via point counting, carbonate coulometry and aragonite content) have been analysed, to assess whether there are any temporal changes which may reflect variation in shallow shelf reef extent. This included the development of XRF scanning measurements for [Sr], as a new proxy for the aragonite content of samples. A calibration line with the equation: Aragonite %=0.0011* Sr count +2.64 (R2 =0.6105, p-value < 0.001) was obtained for turbidite samples from sediment core MD06-3019. The method shows significant promise as a new proxy for quickly establishing the aragonite content of sediment samples. Corroborating the work of previous investigators, turbidites deposited since MIS11 show an increase in average bulk carbonate and aragonite content, a greater dominance of shallow water bioclasts and a higher occurrence of coral fragments. Additionally, both coarse and fine grained turbidites are present, whereas directly before this period only fine grained turbidites occur. However, there is another significant shift in depositional style further back in the record. Prior to MIS23 both coarse and fine grained turbidites are present, the average carbonate content of turbidite layers is higher and there is a greater dominance of shallow water biota. Coral abundance for turbidites at the base of the core can equal values for turbidites at the top of the core. These results challenge the assumption that the only significant evolution on the western New Caledonia margin over the last 1.2Myrs was the expansion of the barrier reef at MIS11. This suggests that the history of the western New Caledonia margin may be more complicated than initially anticipated. These temporal variations in turbidite deposition are interpreted as reflecting changes in the level of carbonate production on the shallow shelf over the course of the 1.26Myr record. Shallow water carbonate production having decreased substantially during the period MIS23-MIS11. There are many possible controls on the shallow water carbonate production; such as: sea surface temperature and salinity, sea-level and nutrient availability. However, it is hypothesised that the principal control is glacial-interglacial sea-level change. It is proposed that prior to MIS23 sea-level was high enough during certain interglacial periods for significant carbonate production to occur on the shelf. However, from MIS23 onwards the climate proceeded into a period of ‘lukewarm’ interglacials which were both cooler and had lower sea-levels. It is hypothesised that during this period sea-level did not rise enough during highstands to flood the shelf sufficiently to allow for significant shallow water carbonate production. The high sea-levels of the long, warm MIS11then allowed for the expansion of the barrier reef (perhaps on substrates provided by former siliciclastic coast lines, deposited between MIS23-11) and its continuation during subsequent interglacial periods until the current day. This pattern of shallow shelf carbonate production is similar to those proposed for the Belize margin and the Gulf of Papua over the last 1.2Myrs. This thesis provides one of the first detailed investigations of gravity deposits in the New Caledonia Trough, providing information on their composition and timing over an unprecedented 1.26Myr time period. This study demonstrates that deep sea turbidites, sourced from shallow shelf areas, can be used to help reconstruct tropical reef growth histories. The results corroborate the work of previous researchers in the area and provide new insights into the history of reefs along the western New Caledonian margin. The main advantage of this method, compared to traditional borehole techniques, is the 10-fold reduction in the age uncertainty of events, to ±10 kyr. In addition, because turbidite material is sourced from a wide area along the coast, the method is able to provide information on reef history over a larger spatial area than single reef boreholes. This method can now be extended globally to help improve knowledge of the timing and history of tropical reef growth during the Quaternary. This will enable a better understanding of how reefs have impacted on, and been affected by, changes in climate, linked by feedbacks mechanisms via the global carbon cycle.

Over the past several decades, rapid progress has been made toward the accurate characterization and control of atoms, made possible largely by the development of narrow-linewidth lasers and techniques for trapping and cooling at ultracold temperatures. Extending this progress to molecules will have exciting implications for chemistry, condensed matter physics, and precision tests of physics beyond the Standard Model. These possibilities are all consequences of the richness of molecular structure, which is governed by physics substantially different from that characterizing atomic structure. This same richness of structure, however, increases the complexity of any molecular experiment manyfold over its atomic counterpart, magnifying the difficulty of everything from trapping and cooling to the comparison of theory with experiment. This thesis describes work performed over the past six years to establish the state of the art in manipulation and quantum control of ultracold molecules. Our molecules are produced via photoassociation of ultracold strontium atoms followed by spontaneous decay to a stable ground state. We describe a thorough set of measurements characterizing the rovibrational structure of very weakly bound (and therefore very large) ⁸⁸Sr₂ molecules from several different perspectives, including determinations of binding energies; linear, quadratic, and higher order Zeeman shifts; transition strengths between bound states; and lifetimes of narrow subradiant states. The physical intuition gained in these experiments applies generally to weakly bound diatomic molecules, and suggests extensive applications in precision measurement and metrology. In addition, we present a detailed analysis of the thermally broadened spectroscopic lineshape of molecules in a non-magic optical lattice trap, showing how such lineshapes can be used to directly determine the temperature of atoms or molecules in situ, addressing a long-standing problem in ultracold physics. Finally, we discuss the measurement of photofragment angular distributions produced by photodissociation, leading to an exploration of quantum-state-resolved ultracold chemistry.

Nuclear plant stainless steel can become contaminated by radionuclides during normal operation whereby the final disposition of these materials then becomes a major decommissioning challenge to address. Characterisation of the chemical and metallurgical processes that underpin contamination is essential in consideration of developing cost effective decontamination and prevention methods, as are in situ measurement techniques that allow assessment of contamination. To address these issues, contamination experiments to simulate the nitric acid-based reprocessing streams of the PUREX (Plutonium Uranium Redox Extraction) process, and alkaline spent fuel storage ponds were investigated. Solution and surface spectroscopic measurements were performed to characterise the sorption behaviour of stable analogues of two high yield fission products, Sr-90 and Cs-137, on as received and 30 % cold rolled AISI Type 304 stainless steel, respectively. In addition Laser Induced Breakdown Spectroscopy (LIBS) was also investigated as a standoff contamination assessment technique. Fission product accumulation was modelled to a second order kinetic fit that considers chemisorption, typically to a hydrous metal oxide surface, as rate controlling. This process is observed to be independent of solution composition and strain processing regime. This behaviour reflects complexation to the passivating surface chromium oxide film, and as determined by depth elemental analysis, effectively inhibits contaminant migration into the bulk material. Environment chemistry and microstructural variables that destabilise the Cr-rich passive film however reduces the passive layer capabilities to effectively inhibit fission product bulk diffusion. The importance of corrosion phenomena towards radionuclide sorption processes necessitates the consideration of metallurgical and chemical factors during the implementation of decontamination approaches to treat affected plant material at nuclear licenced sites. LIBS was found to be a satisfactory technique for measurement of Sr sorbed to steel but Cs could not be detected at the concentrations used in this experimentation. Furthermore, EDX and TOF-SIMS elemental mapping indicated ablated material may be redistributed into the crater profile during elemental analysis. This process has clear implications for the deployment of LIBS for in situ characterisation of nuclear materials as the uncontrolled redistribution of radioactive material certainly violates decommissioning principles.

Neste trabalho é apresentado o potencial de remoção de íons estrôncio de soluções aquosas pelas fibras de coco na forma bruta e na forma ativada com peróxido de hidrogênio, 1% e 4%, em meio básico. Os experimentos de biossorção foram realizados em batelada com 2 mg.L-1 de solução de Sr(NO3)2 e foram estudadas as influências dos seguintes parâmetros: tempo de contato, pH e a eficiência de biossorção das fibras ativadas em comparação com a fibra de coco bruta (FCB). A caracterização das fibras antes e após o tratamento, e a presença de Sr2+ nas fibras foram realizadas por microscopia de varredura eletrônica com detector de espectroscopia de energia dispersiva, espectroscopia de difração de raios X, espectroscopia de infravermelho e por análise térmica. Dentre as fibras estudadas, a fibra de coco ativada com 1% H2O2 (FCA 1) apresentou a maior capacidade de biossorção: 3,6 mg.g-1, nas seguintes condições: 5 mg de biomassa em pH 6, após 90 minutos de tempo de contato à temperatura ambiente. A fibra de coco ativada com 4% H2O2 (FCA 2) levou a uma maior degradação dos constituintes da fibra e consequentemente a uma menor remoção de íons de Sr2+.Para os estudos de modelos de isotermas de biossorção de Sr2+, tanto a FCB quanto a FCA 1 ajustaram-se melhor ao modelo de Langmuir e à cinética de pseudo-segunda ordem. Os parâmetros termodinâmicos energia livre de Gibbs (&Delta;G) e coeficiente de distribuição (KD) foram -0,90 kJ.mol-1 e 265,3L.Kg-1 para a FCB e de -7,2 kJ.mol-1 e 824,3 L.Kg-1 para a FCA1. Esses resultados demonstraram que a FCA 1 possui uma boa eficiência para remover íons de Sr2+de resíduos químicos aquosos e é uma boa alternativa no tratamento de rejeitos radioativos líquidos contendo íons 90Sr. / This work presents the potential of strontium ions removal from aqueous solutions using coconut fiber in raw and treated form with hydrogen peroxide, 1% and 4%, in alkaline conditions. The biosorption experiments were performed in batch mode with 2 mg.L-1 solution of Sr(NO3)2 and the influence of the following parameters were studied: contact time and pH. It was also evaluate the biosorption efficiency of the treated coconut fibers in comparison with the raw coconut fiber (RCF). The fibers characterizations before and after treatment and the presence of the Sr2+ in the fibers were performed by scanning electron microscopy with a detector energy dispersive spectroscopy, diffraction of x-ray spectroscopy, infrared spectroscopy and thermal analysis. Among the studied fibers, the treated coconut fiber with 1% of H2O2 (TCF 1) showed the major biosorption capacity of 3.6 mg.g-1 in the following conditions: 5 mg of biomass at pH 6, 90 minutes of contact time at room temperature. Treated coconut fiber with 4% H2O2 (TCF 2) showed the lowest Sr2+ ions removal due to degradation of the fibers constituents. For studies of biosorption isotherms, both raw and treated coconut fiber (TCF 1) were fitted better to Langmuir model and the kinetics reaction was of pseudo-second order. The thermodynamic parameters Gibbs free energy (&Delta;G) and distribution coefficient (KD) were -0.90 kJ.mol-1 and 265.3 L.Kg-1 for RCF and of -7,2 kJ.mol-1 and 824.3L.Kg-1 for TCF 1. These results demonstrated that the TCF 1 has good efficiency for removing Sr2+ ions in the aqueous chemical waste and is a good alternative in treatment of liquid radioactive wastes containing 90Sr.

Orientador: Rosemary Adriana Chiérici Marcantonio / Resumo: O objetivo deste estudo foi avaliar o efeito do uso de diferentes substitutos sobre o reparo ósseo de defeitos críticos de calvárias de ratos com ou sem osteoporose. Para tanto, foram divididos em três estudos. O estudo 1 avaliou o efeito de diferentes biomateriais sobre o reparo de defeitos críticos de calota (DCC) de 40 ratos saudáveis que foram aleatoriamente divididos em 5 grupos com 8 animais, de acordo com o tipo de biomaterial utilizado para preencher os DCC: Grupo COA (coágulo); Grupo AUT (osso autógeno); Grupo OBD (osso bovino desproteinizado); Grupo HA/ TCP (cerâmica bifásica composta de hidroxiapatita e β-fosfato tricálcio); Grupo TCP (β-fosfato tricálcio). Foram executadas análise microtomográfica para avaliação do comprimento linear remanescente (DLL) do DCC e o volume dos tecidos mineralizados (MT) dentro do defeito nos períodos de 3, 7, 15 e 30 dias após cirurgia. Adicionalmente, foi executado análise histométrica para avaliar a composição do tecido ósseo reparado (% Osso e % Biomaterial) no período de 30 dias. O grupo COA apresentou o menor DLL e MT dentro do DCC e maior % osso do que os outros grupos. O grupo OBD apresentou maior volume de tecidos mineralizados e maior % biomaterial do que o grupo os grupos AUT e TCP. Os grupos OBD e AUT apresentaram maior % osso que o grupo TCP. O estudo 2 avaliou o efeito do enxerto com OBD carregado de estrôncio (Sr) na cicatrização óssea em DCC em 42 ratos saudáveis. Foram feitos 2 defeitos/rato, e um destes aleatoriament... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

The goal of this research was to aid in the fight against the heroin and opioid epidemic by developing new methodology for heroin provenance determination and forensic sample comparison. Over 400 illicit heroin powder samples were analyzed using quadrupole and high-resolution inductively-coupled plasma mass spectrometry (Q-ICP-MS and HR-ICP-MS) in order to measure and identify elemental contaminants useful for associating heroin samples of common origin and differentiating heroin of different geographic origins. Additionally, 198 heroin samples were analyzed by multi-collector ICP-MS (MC-ICP-MS) to measure radiogenic strontium isotope ratios (87Sr/86Sr) with high-precision for heroin provenance determination, for the first time. Supervised discriminant analysis models were constructed to predict heroin origin using elemental composition. The model was able to correctly associate 88% of the samples to their region of origin. When 87Sr/86Sr data were combined with Q-ICP-MS elemental data, the correct association of heroin samples improved to ≥90% for all groups with an average of 93% correct classification. For forensic sample comparisons, quantitative elemental data (11 elements measured) from 120 samples, 30 from each of the four regions, were compared in order to assess the rate of discrimination (5400 total comparisons). Using a match criterion of ±3 standard deviations about the mean, only 14 of the 5400 possible comparison pairs were not discriminated resulting in a discrimination rate of 99.7%. For determining the rate of correct associations, 3 replicates of 24 duplicate samples were prepared and analyzed on separate days. Only 1 of the 24 correct pairs were not associated for a correct association rate of 95.8%. New methods for provenance determination and sample comparison are expected to be incredibly useful to intelligence agencies and law enforcement working to reduce the proliferation of heroin.

Forensic anthropologists increasingly use chemical isotope analysis in the investigation of unidentified human remains, as biochemical georeferencing continually improves with the development of modern reference data of known origins. Isotope variations in trace elements such as strontium (Sr) and lead (Pb) in human teeth are some of the most useful indicators of past domicile in archaeological research and thus have high potential for modern, forensic applications. In this study, high-precision lead isotope analysis was conducted on 63 modern human teeth, which were previously analyzed for strontium isotopes. The results present new lead isotope data for the following countries: United States (n=34), Colombia (n=9), Haiti (n=5), Cape Verde (n=3), Morocco (n=2), El Salvador (n=2), Guatemala (n=2), Honduras (n=2), Jamaica (n=1), Dominican Republic (n=1), Albania (n=1), and United Kingdom (n=1). In addition, the lead and strontium isotope data of 23 modern human teeth from individuals born in Holland, eight teeth from individuals born in Bulgaria, and 26 teeth from individuals born in the U.S. are extracted from the literature to supplement the data analysis. Exploratory data analysis, nonparametric Kruskal-Wallis tests, and one-way analysis of variance (Scheffe post hoc) are conducted using IBM SPSS® Statistics 24 to test for regional variation. Several trends are observed in the lead isotope data that may be relevant to modern forensic contexts involving unidentified human remains: Individuals from the northeast U.S. have relatively distinct 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios when compared to individuals from the rest of the U.S. European and American individuals can be easily distinguished from each other using 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios. Central American individuals have significantly lower 87Sr/86Sr ratios than North American individuals, and these groups can be easily distinguished using lead versus strontium scatterplots. Colombian individuals have significantly lower 87Sr/86Sr ratios than North American individuals, and these groups can be easily distinguished using lead versus strontium scatterplots. Caribbean individuals have significantly lower 87Sr/86Sr isotope ratios than individuals from the northeast U.S., and these groups can be easily distinguished using lead versus strontium scatterplots.