Tuesday, December 7, 2010

Acid Snow

I've heard and read that snow is more acidic than regular lake water and I've often wondered if that is true. I know from experience on winter camping trips that drinking water made from melting snow certainly has a different flavor. It's a known fact that acids taste sour but I'm not sure that I would call the flavor of snow, sour. So I thought I'd look into this a bit with a quick Google search.

Essentially acid snow is just acid rain in a solid form rather than liquid. As a droplet of water falls through the atmosphere it removes water soluble particles such as sulphur dioxide and nitrogen dioxide and combines with them to become more acidic. Typically acid rain has a pH of 4.4 and snow 4.8. My guess would be that the higher pH level of snow can be explained by the fact that a solid will absorb particles less readily than a liquid and will therefore be less acidic.

The pH scale ranges from 0 to 14 with 0 being purely acidic and 14 being purely basic, a pH of 7 is neutral.

While winter camping I used to melt snow for all of my water needs (I don't mind the flavor of snow) but in recent years we have started chopping a water hole in the lake ice so we can have access to fresh liquid water. It is much more convenient to have liquid water available and it saves a lot of time that used to be spent on making water from snow.

Photosynthesis, respiration and decomposition tend to lower the pH levels in lakes and typically the pH of natural water is between 6.5 and 8.5.

So I guess there is some truth to snow being more acidic than water but I'm not sure that this explains the difference in flavors.

Our water hole on the lake ice

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