You’ve heard of “mass” confusion,
But even more confounding is the curious case of trying to figure out mass “per volume” at very low concentrations.
In scientific terms, it’s 35 parts per thousand (ppt) “salty.”
The recipe in your kitchen would call for adding 26 teaspoons of salt per gallon of water. (Easy enough, I have both.)
How about parts per million (ppm)?
Now we’re getting dilute.
The recipe calls for adding 1 teaspoon to sauce pan the size of 31 rain barrels (at 42.5 gallons per barrel).
Can anything that dilute harm us?
Nitrate levels at a concentration of 10 ppm is cause for alarm for one. (That’s one reason why people buy bottled water instead.)
How about parts per billion (ppb)?
(Now this will test how well equipped we are in our kitchen!)
This recipe calls for adding 1 teaspoon (good we already have that one) to a lobster pot the size of 2 Olympic swimming pools.
In the Everglades, total phosphorus in concentrations above 10 ppb is considered a pollutant.
As confusing as all this seems (even to me), I’m glad to know that I am at least semi-well equipped as a hydrologist (going out into the world) if I have nothing else but a “teaspoon” in my hydrologic satchel.
It’s better than the alternative:
Carrying the water!