MadSci Network: Earth Sciences |
Wade, You had the answer yourself! An acid lake does get more acidic as the water evaporates. pH, or acidity and alkalinity, is a physical property of the water. It's based on the amount or concentration of ions in the water (which, combined is the "solution") When we trap the water that comes off a lake or an engineered pond, we can collect it as distilled (pure, clean, nothing else) water, just like if you were to trap the steam that comes out of a tea kettle. If, when the lake evaporates to a low point, the fresh, clean groundwater re-dilutes the lake, the lake will go back to near to its original acidity. But here's a question for you- if we evaporate the lake, and it gets more acidic, what happens if the groundwater that replenishes the lake has just a little bit of acidity to it. Not as much as the lake, just a tiny bit. Or, if a little pond next to the ocean dries out every week for a year- totally dries out, with no water left, and then is replenished by the salty ocean water, how salty does the pond get? Remember- saltiness and acidity are both physical properties, and so the salt and the water, or the acid and the water, can be separated without changing the chemical properties of either the salt (acid) or the water. For extra reading, try doing searches on the water cycle, sea salt ponds, and acid lakes. Some of the acid lakes stuff can get complicated, since nature doesn't like to stay one way or the other for too long (you may have heard "nature abhors a vacuum"). But if you work hard to understand it, and start teaching people who are interested, there are a lot of super cool places you can go in this world that will need your help and expertise. Have fun! --Sarah
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