La Cienega Project
Organ Pipe Cactus National Monument

When you come out to Organ Pipe Cactus National Monument, if you are in the 8th grade
class, you will collect this same data for yourself! The main difference you will notice between
this data and your data are the units. Historically, our tests have units of mg /L, which is
milligrams of DO for one liter of water. The test you will perform will use ppm (parts per
million) as units, which is basically the number of "partsof DO" for each one million "parts"
of water.

If you do the math, you can find that mg/L is actually the same as ppm. Try it and prove it to
yourself! (Remember one liter of water is equal to one kilogram of water).

It is always good to check and know what units you are comparing. In this case, even though
they are different, they are actually equal.

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