Standard defining the isotopic composition of ocean water
Vienna Standard Mean Ocean Water (VSMOW) is an isotopic standard for water, that is, a particular sample of water whose proportions of different isotopes of hydrogen and oxygen are accurately known. VSMOW is distilled from ocean water and does not contain salt or other impurities. Published and distributed by the Vienna-based International Atomic Energy Agency in 1968, the standard and its essentially identical successor, VSMOW2, continue to be used as a reference material.
Water samples made up of different isotopes of hydrogen and oxygen have slightly different physical properties. As an extreme example, heavy water, which contains two deuterium (2H) atoms instead of the usual, lighter hydrogen-1 (1H), has a melting point of 3.82 °C (38.88 °F) and boiling point of 101.4 °C (214.5 °F).[1] Different rates of evaporation cause water samples from different places in the water cycle to contain slightly different ratios of isotopes. Ocean water (richer in heavy isotopes) and rain water (poorer in heavy isotopes) roughly represent the two extremes found on Earth. With VSMOW, the IAEA simultaneously published an analogous standard for rain water, Standard Light Antarctic Precipitation (SLAP), and eventually its successor SLAP2. SLAP contains about 5% less oxygen-18 and 42.8% less deuterium than VSMOW.
A scale based on VSMOW and SLAP is used to report oxygen-18 and deuterium concentrations. From 2005 until its redefinition in 2019, the kelvin was specified to be 1/273.16 of the temperature of specifically VSMOW at its triple point.
^"Thermophysical Properties of D2O" (PDF). Journal of Physical and Chemical Reference Data. 13 (601). 2009.
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ViennaStandardMeanOceanWater (VSMOW) is an isotopic standard for water, that is, a particular sample of water whose proportions of different isotopes...
impurities in water A commonly quoted value of 15.7 used mainly in organic chemistry for the pKa of water is incorrect. ViennaStandardMeanOceanWater (VSMOW)...
temperature is not defined for such subsystems. A For ViennaStandardMeanOceanWater at one standard atmosphere (101.325 kPa) when calibrated strictly per...
isotopologues of water. ViennaStandardMeanOceanWater is the current international standard for water isotopes. Naturally occurring water is almost completely...
Supersaturation Thermodynamics Troposphere Vapor pressure Lide (1992) ViennaStandardMeanOceanWater (VSMOW), used for calibration, melts at 273.1500089(10) K (0...
point of water, the definition of the kelvin would refer to water having the isotopic composition specified for ViennaStandardMeanOceanWater. In 2005...
the triple point of special isotopically controlled water called ViennaStandardMeanOceanWater occurred at precisely 273.16 K and 0.01 °C. One effect...
French-language name for the unit of angular measurement. For ViennaStandardMeanOceanWater at one standard atmosphere (101.325 kPa) when calibrated solely per...
water also depends on the isotopic ratios of the oxygen and hydrogen atoms in a particular sample. Modern measurements of ViennaStandardMeanOcean Water...
to ViennaStandardMeanOceanWater (VSMOW) or Vienna Pee Dee Belemnite (VPDB). Variations in oxygen isotope ratios are used to track both water movement...
based on the melting pressure of helium-3. Kelvin Triple point ViennaStandardMeanOceanWater (VSMOW) Resistance thermometer Platinum resistance thermometer...
are reported. This can mean a material that historically defined an isotopic scale, such as ViennaStandardMeanOceanWater (VSMOW) for hydrogen isotopes...
that of the dalton does) or to a specific isotope ratio, e.g. ViennaStandardMeanOceanWater, this removes a source of ambiguity and variation, but adds...
about temperature. For water, the isotope ratio standard is ViennaStandardMeanOceanWater, and for carbonates, the standard is Pee Dee Belemnite. Using...
enriched/depleted relative to a standard. The field typically normalizes to both ViennaStandardMeanOceanWater (VSMOW) and Standard Light Antarctic Precipitation...
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