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This
is a way of expressing very dilute concentrations
of substances. Just as per cent means out of a hundred,
so parts per million or ppm means out of a million.
Usually describes the concentration of something
in water or soil. One ppm is equivalent to 1 milligram
of something per liter of water (mg/l) or 1 milligram
of something per kilogram soil (mg/kg). |
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