Study: Acid rain now making water bodies — are you ready — more alkaline!

This is precisely the opposite of what the public was told during 1980s acid rain hysteria.

The media release is below.


Eastern US water supplies threatened by a legacy of acid rain

Human activities are changing the water chemistry of many streams and rivers in the Eastern U.S., with consequences for water supplies and aquatic life, so reports a new study in the journal Environmental Science and Technology.

In the first survey of its kind, researchers looked at long-term alkalinity trends in 97 streams and rivers from Florida to New Hampshire. Sites ranged from small headwater streams to some of the nation’s largest rivers. Over the past 25 to 60 years, two-thirds have become significantly more alkaline.

Alkalinity is a measure of water’s ability to neutralize acid. In excess, it can cause ammonia toxicity and algal blooms, altering water quality and harming aquatic life. Increasing alkalinity hardens drinking water, causing pipe scaling and costly infrastructure problems. And, perhaps most alarming, it exacerbates the salinization of fresh water.

In what may seem like a paradox, human activities that create acid conditions are driving the problem. This is because acid rain, acidic mining waste, and agricultural fertilizers speed the breakdown of limestone, other carbonate rocks, and even concrete and cement. The result: alkaline particles are washed off of the landscape and into streams and rivers.

The survey found watershed geology was the strongest predictor of river alkalinization, with rivers receiving water from porous, limestone, and other carbonate rocks being more alkaline. Topography and pollution were also triggers. The most rapid rates of alkalinization were at high elevation sites that were chronically exposed to acid pollution.

Among the rivers impacted by higher alkalinity are those that provide water for Washington, D.C., Philadelphia, Baltimore, Atlanta, and other major cities, the researchers reported. This is due, in part, to acid rain exposure, urbanization, and the extent of land covered by cement and concrete.

Also affected are rivers that flow into water bodies already harmed by excess algae, such as the Chesapeake Bay, where managers are struggling to contain algal blooms that are toxic to fish, oysters, and crabs. Appalachian Mountain streams are also vulnerable. In that region, thin soils and steep slopes cause erosion, and there is persistent exposure to industry emissions.

Noted ecologist Gene Likens, Founding Director of the Cary Institute of Ecosystem Studies and a co-discoverer of acid rain, was among the study’s authors. The extent of alkalinity change in streams and rivers exceeded his expectations: “This is another example of the widespread impact humans are having on natural systems. Policymakers and the public think that the acid rain problem has gone away, but it has not.”

Adding, “Acid rain has led to increased outputs of alkalinity from watersheds and contributed to long-term, increasing trends in our rivers. And this is twenty years after federal regulations were enacted to reduce the airborne pollutants that cause acid rain.”

Lead author Sujay Kaushal, an associate professor and aquatic ecologist at the University of Maryland, notes, “What we are seeing may be a legacy effect of more than five decades of pollution. These systems haven’t recovered. Lagging effects of river alkalinization are showing up across a major region of the U.S. How many decades will it persist? We really don’t know the answer.”


21 thoughts on “Study: Acid rain now making water bodies — are you ready — more alkaline!”

  1. The mechanism described — acid dissolution of rock so that buffering and alkaline materials enter bodies of water — is at least sort of plausible.
    The key question is, how much have different bodies of water changed? Alkalinity is not really “…a measure of water’s ability to neutralize acid.” It’s a measure of the concentration of hydroxide ions (OH-) in solution. It’s true that the hydroxide ions will bond with hydrogen ions (H+, the chemical that makes an acid) and result in a water molecule. Alkalis have other properties, though, so alkalinity is more than “…a measure of water’s ability to neutralize acid.”
    Acid-base character is described on the pH scale from 1 to 12. A lower number is more acid and a higher number is more alkaline. The numbers toward the middle are actually more neutral — the H+ or OH- ions are fewer at 5 or 9 than at 3 or 10.
    If the shift is to a slightly less acid body of water, it would be hard to say that the water is more alkaline. I don’t remember enough chemistry to know where the concerns would begin and I’d have to know a lot about the local life forms and the pH ranges to which they are adapted.
    But y’know, if the acid rain was causing this kind of change, I’da thunk it would have come up sooner.

  2. “But y’know, if the acid rain was causing this kind of change, I’da thunk it would have come up sooner.’

    The reason it didn’t is they weren’t looking for it–they were so convinced the waters were becoming acidic that all of their “research” went into proving their theory. decades later, they see the opposite is happening.

    Just like “global warming”. When it gets really cold, they will call it evidence of “climate change”. The acid rain guys didn’t have a back-up label.

  3. “Acid rain now making water bodies — are you ready — more alkaline!”
    Which mean less Acidification.

  4. John, I’m unaware of a litmus stick which exclusively reports acid but not alkaline. If they were testing for acidity, they would have to have known the pH levels!

    But, isn’t the mechanism they’re reporting make the pH level limiting? That is to say, if it is bicarbonate which is causing this, then the pH level isn’t going to swing too high?

  5. Howdy suyts
    Keep in mind I’m dusting off high-school chemistry here, back when the periodic table was just the periodic row.
    A buffer like bicarbonate interacts with an acid or a base to neutralize it. It’s commonly a weak acid or base itself, but it doesn’t just bind H+ and OH- ions. Buffers will not turn an acid lake to base nor vice versa.
    If you mix an acid and a base, their ions will bond to form water. I dunno what else may happen – exothermic (heat-producing) reactions, if I recall correctly.

  6. Hi, Geoff:
    The simple definition of alkalinity is the ability to neutralize an acid. The definitions get a bit more complicated when you go to things like carbonate alkalinity, etc. I believe some of this article is pushing toward the buffering effect you get from carbonates. If I can remember all the way back to acid rain, I thought they were going to dissolve all the carbonate and make the ponds/lakes/streams acidic. Apparently we have changed our minds when it didn’t really happen as predicted.

  7. The words “acid” and “alkali” are now subject to the same level of hand-waving abuse by the ignoranti as the word “science”.
    We are talking well-characterized aqueous chemistry here. Give me the numbers!

  8. Hi, again, Geoff,
    A strong acid/strong base titration curve is vertical about pH 7, so a drop of acid or base takes you a long way on the pH scale. A buffer interferes with the simple H+ + OH- =>H2O and flattens the curve. Buffers are used to hold the pH in certain ranges, so in the case of acid rain, the carbonates from rock dissolution buffer the receiving streams and don’t allow the pH to drop as predicted.
    Years ago I started up a wastewater plant after it had been built. The aerobic digestion section works best at a basic pH and with a certain alkalinity. Someone decided we could achieve that with sodium hydoxide solution. The pH and alkalinity dropped so fast that we used huge amounts of caustic. Replacing the caustic with lime provided a buffer and we were able to hold the pH and alkalinity much easier.

  9. This is a handwaving argument, TC, without numbers. These folks are looking for another reason to get save the Bay money. They have been pushing on nitrate, phosphorous and sediment, so why not try some acid rain for along with the mix? BTW, if we have had a quarter century or more acid rain reduction (reduced fuel sulfur, NOx), wouldn’t the freshwater respond with a pH increase?

  10. It sounds like stopping acid rain would have caused an increase in alkalinity. Are they sure that that isn’t what they are measureing? Did they expect nothing to change when they stopped acid rain? If so, why did they do it?

  11. I don’t get the bit about alkalinity causing algal blooms. I’ve always thought algal blooms caused alkalinity. High alkalinity stymies photosynthesis. Not that the range they are talking about is high by any measure, but I think they have reversed the cause and the effect. It is possible though, that if it is bicarbonate alkalinity, the algae assimilate inorganic carbon (which they will happily do) and grow because of it.

  12. When I was taking high school chemistry and learning about pH, acids and bases, there was a shampoo commerical that talked about how some shampoos would raise the pH of hair but this shampo would lower the pH of hair. By then I knew that hair had better be in a pretty narrow pH band — I dunno what a hair pH of 4 would do to your scalp but I don’t want it to happen to mine!
    Since the pH scale is logarithmic, yes, a small amount of acid, base or buffer near the center will produce a bigger change in the number than if you’re more acid or more base.
    I don’t think my old chem teacher, who resembled Gandalf with his eyebrows, ever defined alkalinity as the capacity to neutralize an acid, though it would involve that property. Bases and acids have properties when the other is not around; lye is a strong oxidizer without throwing any acid into it.

  13. My chem teacher was Mr. Sproul — I have him in my mind’s eye forty years later, which says something about his effect.

  14. My high school teacher was “aunt” Betty Abernathy, and everyone remembers her. Most of the chemistry I had 50 years ago stuck. We had fun in her classes.
    “lye is a strong oxidizer without throwing any acid into it.” “lye” is either sodium hydroxide or potassium hydroxide, the term can refer to either. Both are strong bases (NaOH or KOH) and will corrode some metals but are not oxidizers. Alkalinity is measured by titration with a strong acid. Acidity is measured by titration with a strong base.

  15. My guess is algal blooms are more related to the phosphorous (phosphate) and nitrogen (nitrate, ammonia) content of the water. At least that’s the claim when they beat on wastewater plants.

  16. It sounds to me like they’re suggesting that acid erosion of limestone causes chunks of limestone to break away, which could further on dissolve and decrease the acidity. Other than this (inferred) mechanical breakdown of the rock, there is no way to add acid to a solution and thereby make a solution less acidic. Utterly impossible no matter what kind of buffer you’ve got.

  17. There is an important semantic difference between “more alkaline” and “less acidic”, for a professional chemist to misuse those phrases smacks of propaganda to me. Couple that with the usual omission of hard numbers in favor of “increase” or “decrease” and you get a nice, vaguely alarming statement that doesn’t actually say anything. How large was the shift? Certainly not whole numbers or they’d have published it. Are we talking tenths, hundredths? What is the normal seasonal variation in pH? What is the range of pH that sensitive species can survive in controlled conditions? Does anyone calling themselves “scientist” actually do experiments anymore, or is it all just glorified data entry?

  18. More alkaline fresh water meeting (supposedly) more acidic seawater. Seems like we’re edging toward recognizing a natural buffering process that keeps oceans nearly neutral.

  19. I find the whole thing utter nonsense! What is different now compared to when acid rain was considered a problem because it acidified the waters??? Don’t you guys remember when “scientists” called some bodies of water having the pH of VINEGAR??

    Somebody explain to me WHY it’s causing alkaline conditions NOW and not 20 years ago??

  20. I just don’t agree with that at all. You take a body of water and stick a pH meter in it. There are only three possible states: acidic, neutral or basic. Then you go around and check others.

    I think that the answer is they got all this information and just IGNORED the alkaline bodies of water and falsely raised the issue of acid rain.

    Let’s call it the acid rain hockey stick!

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