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One part per billion (ppb) denotes one part per 1,000,000,000 (10 9) parts, and a value of 10 −9. This is equivalent to about three seconds out of a century . One part per trillion ( ppt ) denotes one part per 1,000,000,000,000 (10 12 ) parts, and a value of 10 −12 .
1 volume percent = 10,000 ppmv (i.e., parts per million by volume) with a million being defined as 10 6. Care must be taken with the concentrations expressed as ppbv to differentiate between the British billion which is 10 12 and the USA billion which is 10 9 (also referred to as the long scale and short scale billion, respectively).
0.1 × ( 12 ÷ 8 ) = 0.15 grain per dscf when corrected to a gas having a specified reference CO 2 content of 12 volume %. Notes: Although ppmv and grains per dscf have been used in the above examples, concentrations such as ppbv (i.e., parts per billion by volume), volume percent, grams per dscm and many others may also be used.
Ground-level ozone (O 3), also known as surface-level ozone and tropospheric ozone, is a trace gas in the troposphere (the lowest level of the Earth's atmosphere), with an average concentration of 20–30 parts per billion by volume (ppbv), with close to 100 ppbv in polluted areas.
The abundance of elements in Earth's crust is shown in tabulated form with the estimated crustal abundance for each chemical element shown as mg/kg, or parts per million (ppm) by mass (10,000 ppm = 1%).
Values are given as pollution free monthly mean mole fractions in parts-per-billion. [1] Atmospheric methane is the methane present in Earth's atmosphere. [2] The concentration of atmospheric methane is increasing due to methane emissions, and is causing climate change. [3] [4] Methane is one of the most potent greenhouse gases.
If the IPK's value were to have been definitively proven to have changed, one solution would have been to simply redefine the kilogram as being equal to the mass of the IPK plus an offset value, similarly to what had previously been done with its replicas; e.g., "the kilogram is equal to the mass of the IPK + 42 parts per billion" (equivalent ...
The human olfactory system is extremely sensitive to geosmin and is able to detect it at concentrations as low as anywhere from 0.4 parts per billion [14] to 5 parts per trillion. [15] It is proposed that this extreme sensitivity to geosmin evolved in humans or their ancestors to aid them in their search for scarce water, but this is not ...