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  2. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    At 1 ppm the solution is a very pale yellow. As the concentration increases the colour becomes a more vibrant yellow, then orange, with the final 10,000 ppm a deep red colour. In science and engineering , the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities , e.g. mole fraction or ...

  3. Grain per gallon - Wikipedia

    en.wikipedia.org/wiki/Grain_per_gallon

    It translates into 1 part in about 58,000 parts of water or 17.1 parts per million (ppm). ... 1 mg/L (ppm) = 0.058417831 grains per US gallon; See also. dGH; References

  4. Total dissolved solids - Wikipedia

    en.wikipedia.org/wiki/Total_dissolved_solids

    Most aquatic ecosystems involving mixed fish fauna can tolerate TDS levels of 1000 mg/L. [10] Daphnia magna with eggs. The fathead minnow (Pimephales promelas), for example, realizes an LD 50 concentration of 5,600 ppm based upon a 96-hour exposure. LD50 is the concentration required to produce a lethal effect on 50 percent of the exposed ...

  5. Hard water - Wikipedia

    en.wikipedia.org/wiki/Hard_water

    Parts per million (ppm) is usually defined as 1 mg/L CaCO 3 (the definition used below). [20] It is equivalent to mg/L without chemical compound specified, and to American degree . Grain per gallon (gpg) is defined as 1 grain (64.8 mg) of calcium carbonate per U.S. gallon (3.79 litres), or 17.118 ppm.

  6. Air pollutant concentrations - Wikipedia

    en.wikipedia.org/wiki/Air_pollutant_concentrations

    45 × ( 20.9 - 3 ) ÷ ( 20.9 - 5 ) = 50.7 ppmv of NO x. when corrected to a dry gas having a specified reference O 2 content of 3 volume %. Note: The measured gas concentration C m must first be corrected to a dry basis before using the above equation.

  7. Useful conversions and formulas for air dispersion modeling

    en.wikipedia.org/wiki/Useful_conversions_and...

    Atmospheric pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude because the atmospheric pressure decreases with increasing altitude.

  8. Drinking water quality standards - Wikipedia

    en.wikipedia.org/wiki/Drinking_water_quality...

    A parametric value in this context is most commonly the concentration of a substance, e.g. 30 mg/L of iron. It may also be a count such as 500 E. coli per litre or a statistical value such as the average concentration of copper is 2 mg/L.

  9. Alkalinity - Wikipedia

    en.wikipedia.org/wiki/Alkalinity

    Alkalinity is typically reported as mg/L as CaCO 3. (The conjunction "as" is appropriate in this case because the alkalinity results from a mixture of ions but is reported "as if" all of this is due to CaCO 3.) This can be converted into milliequivalents per Liter (meq/L) by dividing by 50 (the approximate MW of CaCO 3 divided by 2).