نتایج جستجو برای: Sulfur isotopes
تعداد نتایج: 56644 فیلتر نتایج به سال:
The sulfur isotopic composition of dissolved sulfate in seawater has varied through time. Distinct variations and relatively high rates of change characterize certain time intervals. This allows for dating and correlation of sediments using sulfur isotopes. The variation in sulfur isotopes and the potential stratigraphic resolution of this isotope system is discussed and graphically displayed.
Separating the contributions of anaerobic oxidation of methane and organoclastic sulfate reduction in the overall sedimentary sulfur cycle of marine sediments has benefited from advances in isotope biogeochemistry. Particularly, the coupling of sulfur and oxygen isotopes measured in the residual sulfate pool (δOSO4 vs. δSSO4). Yet, some important questions remain. Recent works have observed pat...
In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: a b s t r a c t a r t i c l e i n f o The distribution of sulfur isotopes in geological materials reveals information about ...
Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with (13)C-labeled methane showed co-occurring sulfate reduct...
sar-kuh porphyry copper deposit is located 6 km southwest of the sar-cheshmeh copper mine, kerman province, iran. based on field geology, petrography and fluid inclusions studies, four alteration types have been identified in the sar-kuh area. early hydrothermal alteration formed a potassic zone in the central parts of mamzar granite/grano-diorite stock and propylitic alteration in its peripher...
The shell structure underlying shape changes in neutron-rich nuclei near N = 28 has been investigated by a novel application of the transient-field technique to measure the first-excited-state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed 40S does not ...
1. Background 2. Elements, Nuclides, and Stable Isotopes 3. The Mass Spectrometer and Isotope Ratio Measurement 4. Isotope Fractionation 5. Temperature and Fractionation 6. Stable Isotopes in the Hydrologic Cycle 7. O in Minerals and Rocks 8. C and Carbon Cycling 9. N Cycling in Watersheds 10.S and the Sulfur Cycle 11. Chlorine and Bromine Isotopes 12. Light Lithophile Elements: δLi and δB Glos...
Title of Document: SULFUR ISOTOPE FRACTIONATIONS IN BIOLOGICAL SYSTEMS: INSIGHT INTO THE PROTEROZOIC BIOSPHERE David T. Johnston, Ph.D. 2007 Directed By: Professor J. Farquhar, Department of Geology and ESSIC This study focuses on developing a framework for interpreting isotopic fractionations in the four stable sulfur isotopes, with a special focus on microbial effects. Calculations of low tem...
The effect of organic enrichment of sediments on the composition of stable sulfur isotopes (δ34S), sulfide invasion (Fsulfide) and concentrations of total sulfur (TS) and elemental sulfur (S0) in the seagrass Posidonia oceanica was investigated along transects from 3 Mediterranean fish farms in Spain, Italy and Greece. The δ34S decreased and Fsulfide, TS and S0 decreased with distance from the ...
Sulfur stable isotopes are increasingly being used as tracers of material processing in studies of both modern and historical food webs. Preparation of plant and animal material for isotope analysis routinely includes steps that remove inorganic material not normally assimilated by consumers. Whereas acidification of samples is known to assist with this for some elements (carbon), it can produc...
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