نتایج جستجو برای: sulfur isotopes
تعداد نتایج: 56644 فیلتر نتایج به سال:
Early geodynamic processes modeled the surface of the Earth, providing suitable environments and energy sources for the development of life. Studying the ancient biogeochemical cycles is thus a valuable way to understand the physicochemical conditions of the early environments, such as the redox state of the primitive oceans and the atmosphere. To investigate early biogeochemistries, the measur...
Oxygen isotopes in marine sulfate (delta18O(SO4)) measured in marine barite show variability over the past 10 million years, including a 5 per mil decrease during the Plio-Pleistocene, with near-constant values during the Miocene that are slightly enriched over the modern ocean. A numerical model suggests that sea level fluctuations during Plio-Pleistocene glacial cycles affected the sulfur cyc...
The Muteh gold district is located about 70 km northeast of Golpaygan within Sanandaj-Sirjan metamorphic zone of Zagros Structural Belt. Geological studies show that the area had been under poly - phase metamorphism. Gold mineralization occurs in metamorphic complex which consists mainly of green schists, meta-volcanics, and gneisses. Shear zones are the host of gold mineralization, and intense...
We report the first Ni and Cr stable isotope data for ureilite meteorites that are mantle residue of a carbon-rich differentiated planet. Ureilites have similar compositions as chondrites, suggesting core-mantle differentiation parent body (UPB) did not fractionate isotopes. Since size Earth is potentially larger than UPB; with diameter >690 km), resulting in higher temperatures at boundary Ear...
Cesium radioactive isotopes (134Cs and 137Cs) are dangerous to human health due to their long half-life and high solubility in water. Nuclear experiments, wars, and nuclear plant accidents have been the main sources of Cs release into the environment. In recent years, several methods have been introduced for the elimination of Cs radioactive isotopes from contaminated wate...
The water column in brackish and saline lakes hosts various forms of sulfur including sulfide (hydrosulfide), elemental, thiosulfate, sulfate sulfur. unequal distribution these reduced species indicates the presence two opposing processes - reduction oxidation newly formed hydrogen sulfide. scale varies among lakes, resulting differing proportions forms. bacterial ions is confirmed by a signifi...
Present address: S.C. Hsu, IT Corporation, 111 N. Canal St, Suite 941, Chicago IL 60606, USA Abstract Acid drainage containing high levels of iron, manganese, and sulfate is a pollution problem widely associated with abandoned coal mines. The remediation of these sites commonly falls to public agencies, so policy-makers need to allocate scarce resources over many sites and to find cost-effectiv...
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