From Ocean Teacher Library
Obsolete Parts-per-X Chemistry UnitsContents |
Background
These "units" are sometimes encountered in environmental data, particularly in reports dealing with trace contaminants (e.g. metals, hydrocarbons and pesticides). They are outdated, and their use is strongly discouraged. All of these "units" were supposed to be based on mass-per-mass ratio, but many measurements were actually based on mass-per-liter, assuming that one liter weighs a kilogram (an error of up to 3%).
Conversion Table
| Names & Symbols Historically Used | Actual Meaning | Preferred Units Today |
| parts per thousand, parts per mille, ‰, 10-3 | grams per kilogram | [g/kg] |
| parts per million, ppm, 10-6 | milligrams per kilogram | [mg/kg] |
| parts per billion, ppb, 10-9 | micrograms per kilogram | [ug/kg] |
| parts per trillion, ppt, 10-12 | nannograms per kilogram | [ng/kg] |
Subsections of this Article
No subsections available
Information about this article
Short title: Parts-per-X
Description: none
Expertise level: beginner
Author: Murray.Brown
Approval status: approved
Approved by: Murray.Brown
Last change: 2009-8-4
Subsection of: Chemical Oceanographic Measurements
Contact
If you have any direct comments or suggestions for the author of this page then please feel free to send an email to the author (listed above). For discussions on this page please use the discussions page.,
