Test seawater for pH (it is generally pH 8 or basic).
Compare to drinking water (neutral or slightly acidic/basic).
Compare to stream water, pond water and fish tank water (usually neutral).
Students might also want to test the pH of their spit (neutral).
Water chemistry varies with the kind of rock that the water flows over/through, and the chemicals that are added during treatment.
Ocean water becomes more acidic as more carbon dioxide dissolves in it, which happens as the atmospheric carbon dioxide goes up.
Vancouver drinking water is from North Vancouver watersheds, and is naturally slightly acidic. The treatment process makes it a little higher pH.
From Metro Vancovuer website 2021:
Metro Vancouver currently delivers water with a pH of 7.7.
Adjusting the pH is an existing key component of Metro Vancouver’s water treatment process because our untreated source water is naturally slightly acidic. Increasing the pH to a target range of 8.3 to 8.5 will:
• Reduce the release of copper from pipes in buildings caused by low pH in the region’s water;
• Reduce leaks in pipes caused by copper corrosion;
• Help preserve the lifespan of pipes and hot water tanks; and
• Reduce green stains on tubs, sinks, and grout.