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Search Results: 1 - 10 of 1416 matches for " Isotope "
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Evaluation of Accuracy and Precision of IRMS by Using Standard Materials and Applications  [PDF]
J. Y. Hwang, B. K. Kim, M. S. Kim, J. W. Choi, T. S. Kim, W. S. Lee
Journal of Agricultural Chemistry and Environment (JACEN) , 2016, DOI: 10.4236/jacen.2016.54022
Abstract: The isotope ratio mass spectrometer (IRMS) is an instrument that measures both of the elemental contents and isotope ratios of hydrogen, oxygen, carbon, nitrogen and sulfur in environmental samples at the same time. In this study, we want to try to get two main goals; first, to make up for setting the analytical conditions such as accuracy and precision, second, to apply for comparing of the carbon and nitrogen isotope ratio of sediments in the abandoned mine located in middle province of Korea. For the first goal, a recently introduced IRMS was used to analyze CRM (certified reference materials), which helped to make up the analytical conditions of carbon and nitrogen isotope ratios. So, the accuracy and precision of isotope ratios and elemental contents were also assessed simultaneously, and also the results were very satisfactory. The analytical results of carbon reference materials (EMA-P2) showed an accuracy of -2.801 × 10‰ ± 0.01‰ (2σ) and a precision of 0.009‰ in the mass range from 0.008 μg - 0.162 μg. For nitrogen reference materials (EMA-P2), an accuracy of -1.632‰ ± 0.72‰ (2σ) was obtained in the mass range from 0.082 - 0.162 mg. These values of accuracy and precision are higher than those reported by other studies. For the second goal, carbon and nitrogen isotopes in river sediment near abandoned mines were analyzed based on the established analytical conditions. The result suggested that carbon isotope ratios ranged from -22.5‰ - -7.5‰ and nitrogen isotope ratios from -1.9‰ - 7.9‰. By comparing the isotope ratios and sampling sites of sediment, we know that the nitrogen isotope values in samples of entrance area of mine are greater than those of the farm house area, which is indicating the effects of organic materials. So, we could guess that the newly accumulated organic materials were much more in the farm house area than mine entrance area. And a result of this study, the accuracy and precision tests of IRMS using certified reference materials were very satisfactory and optimum analytical conditions were established well. And also, it was found that the applications of isotopic analysis for environmental samples by using the IRMS could be very useful for the studies on tracing pollution sources.
System for High Throughput Water Extraction from Soil Material for Stable Isotope Analysis of Water  [PDF]
Timothy S. Goebel, Robert J. Lascano
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2012, DOI: 10.4236/jasmi.2012.24031
Abstract:

A major limitation in the use of stable isotope of water in ecological studies is the time that is required to extract water from soil and plant samples. Using vacuum distillation the extraction time can be less than one hour per sample. Therefore, assembling a distillation system that can process multiple samples simultaneously is advantageous and necessary for ecological or hydrological investigations. Presented here is a vacuum distillation apparatus, having six ports, that can process up to 30 samples per day. The distillation system coupled with the Los Gatos Research DLT-100 Liquid Water Isotope Analyzer is capable of analyzing all of the samples that are generated by vacuum distillation. These two systems allow larger sampling rates making investigations into water movement through an ecological system possible at higher temporal and spatial resolution.

Preserved Sm-Nd Isotopic Composition as Useful Provenance Indicators in Neoproterozoic Sandstones in the Voltaian Basin, Ghana  [PDF]
Chris Anani, Daniel Asiedu, Johnson Manu, Prosper Nude, Jacob Kutu, Patrick Asamoah Sakyi
International Journal of Geosciences (IJG) , 2012, DOI: 10.4236/ijg.2012.33049
Abstract: The provenance of sandstones derived from theLower Voltaian Kwahu-Morago Group and the Middle Voltaian Oti-Pendjari Group of the Neoproterozoic Voltaian basin are discriminated by their Sm-Nd Isotopic compositions. Plots from the Sm-Nd data suggested provenance of the Kwahu-Morago Group to be from the Birimian metasediments and associated “basin type”granitoids. The Sm-Nd studies have further revealed an average TDM model age of whole rock samples in the Kwahu-Morago Group to be 2.2 Ga which shows that this portion of the Voltaian Supergroup represents eroded remnants of “basin type” granitoids. Sm-Nd data from the Oti-Pendjari Group suggested provenance from the Birimian volcanic rocks and probably with contribution from the Pan African rocks. Its average TDM model age of whole rock samples was 2.0 Ga, which generally falls in the range of the model ages for the basement Birimian volcanic rocks as well as the model ages for the granitoid rocks and thus suggests the major source rock of the Oti-Pendjari Group as coming from the volcanic belts. The model ages for both groups seem to indicate clastic supply from an early Proterozoic crustal provenance. This study shows that whole rock isotopic analyses can also be complementary in providing an insight into the origin and development of sedimentary successions.
Determining the Authenticity of Artifacts by Oxygen Isotope Analysis  [PDF]
Joel Kronfeld, Amnon Rosenfeld, Howard R. Feldman
Open Journal of Geology (OJG) , 2013, DOI: 10.4236/ojg.2013.34036
Abstract:

A technique used to determine the authenticity of artifacts that compares the oxygen isotopic composition of speleothems to the carbonate included within the patina of unprovenanced artifacts is of questionable value. The unprovenanced Jehoash Inscription Tablet and James Ossuary are of potentially immense historical and cultural importance. Nevertheless, they both were rejected by workers based on the oxygen isotope technique which provided the major foundational evidence of forgery in the longest running archaeological trial in Israel. Nevertheless, both these artifacts were determined not to be forged. The initial incongruence between the oxygen isotopes of the speleothems of the Soreq cave (Israel) purported to represent the unique composition of Jerusalem rainfall, and the patina on the artifacts, can be readily explained by the accretion of materials and geo-biochemical processes expected in normal patina formation in the Jerusalem region. The patina formation involves sporadic events in disequilibrium kinetic processes that are opposed to the equilibrium formation of speleothems in a sealed cave. Moreover, 23 of 56 patina samples (41%) on well-documented ancient artifacts from Israel yielded oxygen isotope values greater or lower than the expected speleothem values of -4 δ18O ‰ [PDB] to -6 δ18O ‰ [PDB]. Thus, the speleothem-patina correlation is invalid and the applied oxygen isotopes technique for determining the authenticity of patinas on artifacts is not a useful tool in the authentication of artifacts.

Paleoclimate reconstruction during MIS5a based on a speleothem from Nerja Cave, Málaga, South Spain  [PDF]
C. Jiménez de Cisneros, E. Caballero
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.55067
Abstract:

Speleothems from Nerja Cave in southern Spain provide a record during interglacial period MIS5a. Period of speleothem deposition occurred from 70,000 90,000 yr ago. Oxygen (δ18O) and hydrogen (δD) isotope ratios of speleothem and fluid inclusions enable the reconstruction of climatic variability in this region of southern Spain. Fluid inclusions trapped in speleothems represent samples of drip water from which the speleothems grew. The isotopic compositions of cave dripwaters approximate average annual δ18O and δD of precipitation, therefore δ18O can be calculated from D/H of inclusion water using the MWL relationship δD = 8δ18O + 10. The measurements of the δD values of fluid-inclusion water and δ18O values from speleothems have been applied to paleoclimate reconstruction in Southern Spain indicating a colder condition than at present.

13C/12C Isotope Fractionation during Aerobic and Anaerobic Biodegradation of Naphthalene  [PDF]
Luis E. Lesser-Carrillo
International Journal of Geosciences (IJG) , 2014, DOI: 10.4236/ijg.2014.52022
Abstract:

Microcosm experiments were conducted to determine the fractionation of stable carbon isotopes during biodegradation of naphthalene. The microcosms were performed under aerobic conditions, anaerobic (amended with sulfate, amended with nitrate and with no amendments) and sterile controls. The liquid phase was analyzed to determine naphthalene concentration and stable carbon isotope signature. Aerobic microcosm showed that naphthalene degraded aerobically within 60 hours. The δ13C increased from -25.5‰ to -25.1‰ (enrichment of 0.4‰ ± 0.08‰) in a single sample in which 95% of the naphthalene was biodegraded. Anaerobic microcosms show that after 288 days, the microcosms with no amendments, amended with nitrate and amended with sulfate had consumed respectively 30%, 50% and 60% of naphthalene on average, compared to control microcosms. Under the denitrifying conditions, the δ13C of naphthalene increased from -25.2‰ to -23.9‰ (enrichment of 1.3‰ ± 0.3‰) after a 95% of naphthalene biodegradation. For the unamended microcosms, a slight enrichment on δ13C napththalene was detected, from -25.2‰ to -24.5‰ (enrichment of 0.7‰ ± 0.3‰) after a biodegradation of approximately 65% of naphthalene (after 288 days). For sulfate reducing microcosms, no significant changes were detected on the δ13C during naphthalene biodegradation.

Fusion Platform for Renal Cyst Characterization  [PDF]
Hatem Besbes, Wathek Belhajamor
Open Journal of Medical Imaging (OJMI) , 2015, DOI: 10.4236/ojmi.2015.51002
Abstract: This work concerns the field of diagnostic aids that facilitate diagnostic decisions for practitioners, especially in medical imaging. The pathology in question, in this study, is the renal cyst. The diagnostic process starts from simultaneous acquisitions of double isotope (Teechnetium-99 m and Iodine-131) scintigraphic images. Then, the platform allows the fusion of these images and the calculation of a pathological parameter that permits the characterization of the state of the dysplasic kidney by comparing it with the normal one. The final result is fusion images annotated by the pathological parameter value.
Slope Year for the U-Pb Dating Method and Its Applications  [PDF]
Jie Yuan
Open Journal of Geology (OJG) , 2015, DOI: 10.4236/ojg.2015.55032
Abstract: The slope year tslope for the U-Pb dating method is given as \"\", where λ238 and λ235 are the decay constants for 238U and 235U, respectively, and k is the slope of the tangent line at a point on either the Concordia or Discordia line. These two lines are determined by the
Uso da técnica HRICP-MS na avalia??o dos isótopos de boro em eucalipto
Mattiello, Edson Marcio;Ruiz, Hugo Alberto;Silva, Ivo Ribeiro da;Sarkis, Jorge Eduardo de Souza;
Química Nova , 2011, DOI: 10.1590/S0100-40422011000300025
Abstract: the 10b isotope tracer technique is essential to study the b mobility in plants. factors that can influence the quality of measured b isotope ratios were optimized experimentally using high resolution inductively coupled plasma mass spectrometry (hricp-ms). an isotopically certified standard (nist srm-951) was used. the best combination was obtained using a resolution of 400, a rf power of 1250 w, followed by 15 measurements over a 10-s integration period each (15*10). utilizing this approach it was possible to obtain a precision of 0.3 % in standard material and 2z % in the experimental samples. the results show the importance of establishing optimized work conditions before carrying out the analytical series.
H-O ISOTOPE COMPOSITION OF SHANHAIGUAN MIAROLITIC ALKALINE GRANITE

科学通报(英文版) , 1989,
Abstract:
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