The pH scale


Ongoing discussion about the potential effects of ocean acidification on deep-sea corals has me wondering about the case of acid rain in North American lakes. This is something we understand much better. Environment Canada has a great looking and informative Freshwater Website that includes this handy graphic here.

Isn’t it amazing that acid rain can have almost the same pH as battery acid? And that freshwater fish can survive in such a large range of conditions? I find it remarkable. Of course, you won’t find “freshwater corals” in any lake, so its just food for thought, a bit like comparing apples to oranges.

Dr. M (1729 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, a National Science Foundation supported initiative. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (, a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web. His forthcoming book, Science of the South (, connects cultural icons of South such as pecan pie with the science behind them.

2 comments on “The pH scale
  1. If you look at blackwater streams in South America, Rio Negro for instance, (Google Rio Negro pH) you will find fish, insects, snails, and crustaceans living in pH as low as 3.5. The thing that I find amazing is that many of the catfishes, particularly the doradids, have well developed bony plates. One of the doradids (don’t know the species) eats apple snails. One would think the fish would get calcium from the snail shells. However, the shells pass through the gut and come out unscathed and undigested.

  2. Britain also has generally very clean water, but our corrupt Government wants to add Fluoride, not in its natural form of Calcium Fluoride which is beneficial at not more than 1 ppm.

    But because a powerful lobby in the chemical industry has waste products known as Hexafluorosilicic Acid or Di-sodium Hexafluorosilicate the Government has authorised the “medication” of our water supplies against the wishes of the people.

    The truth is that the cost of setting up this plant and dosing it into the water far exceeds the cost of educating the 1% of the populace who don’t wash their teeth! Indeed, where this material has been added, we find fluorosis of the teeth and serious bone embrittlement, the latter of course most affects the elderly and the British Government doesn’t believe they have any rights to a life.

    Of course given that our Government is as bent as £9 note, what is the next medication they will want to add? Some tranquillisers to stop us reacting to their criminal activities?

    I shall drink certain pure bottle waters until I know our main water supply is not being contaminated for political and mercenary aims.

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