Author: Dr. Michael Chase, 16th May 2019
SCOPE
This article describes the method and PRELIMINARY outcome of a relatively low cost “laboratory” (kitchen) experiment on the response of seawater pH to increases in atmospheric CO2.
When additional CO2 is added to the air above seawater the chemistry of the water is expected to change, and there is much focus on the pH measure of acidity. I find that the change in pH when equilibrium is established is readily detectable with a low cost portable pH meter with 0.01 resolution, but the measured size of the effect appears to be significantly smaller than reported in the recent scientific literature. This article deals mostly with the experimental method and results.
EXPERIMENTAL SET-UP
A schematic plan of the experimental apparatus is shown in the following figure. A 2-litre “airtight” food storage jar contains seawater and air, and portable (battery powered) instruments to measure seawater pH and atmospheric CO2 level, with alterations to the latter by injection of pulses of additional CO2. The water is mixed continuously by a magnetic stirrer.
The actual experimental system used is shown in the following photo, the pH meter is white, and the CO2 meter is grey, with its air intake visible just above the water surface. Food storage technology provided the 2-litre airtight container, the plastic “table” that holds the CO2 meter just above the water surface, and “Cling Film” to protect the CO2 meter from getting wet, with a hole cut for the air intake. Details of the meters used, and of the magnetic stirrer, are given at the end of the article.
The original plan was to use a small portable electric fan to mix-up the air, but it was found that the batteries ran-out after about an hour, insufficient time to achieve pH equilibrium, which is found to take around 10 hours.
CO2 GENERATION & INJECTION
CO2 was generated by adding vinegar to bicarbonate of soda in a beaker (with splash guard), injected via an unused ear syringe, a plastic syringe or eye drop dispenser could be substituted:
In a draft-free room the CO2 generated in the beaker can be thought of as a relatively dense fluid which remains there, and which can be drawn into a suitable device and injected into the 2-litre glass container. The aim is to get around 1000 ppm of CO2 in the 2-litre glass container, which is 1 part in a thousand, i.e. 2 ml of CO2 at atmospheric pressure, which can be easily generated and captured.
SEAWATER
Seawater samples of around 450 ml each time were obtained from the shoreline near Weymouth in Dorset, on the South coast of England. The shoreline had some seaweed, which may influence the pH. Each sample was stored in a sealed 500 ml plastic bottle in the “laboratory” overnight to warm it to the laboratory air temperature.
PRELIMINARY RESULTS
Each run of the experiment lasts around 12 hours, which is roughly the observed time required for pH equilibrium to be achieved, with data recording at 15-minute intervals. The runs start mid-morning and run to around 10 pm, a period in which the room temperature remains fairly constant.
The following figure shows early results for 3 runs, one with no injected CO2 (uppermost data), one with injected CO2 such that around 820 ppm was measured (shown in blue with a constant +0.2 shift in all pH values), and one where the final CO2 level was around 1500 ppm:
DISCUSSION
If the recent growth rate of around 2.4 ppm per year of atmospheric CO2 is maintained then the level at the end of the 21st century will be around 600 ppm, with a change in seawater pH of around 0.15, which is considerably lower than figures quoted in the scientific literature. Note that the change of 0.15 in pH applies to seawater of 8.8 pH, which is at the high end of the observed range. Hydrogen ion concentration at a pH of 7.8 is ten times higher than for a pH of 8.8, so the change of pH in 7.8 pH seawater may be even lower than 0.15.
EQUIPMENT DETAILS
· pH meter: Hanna Instruments HI 98108
· CO2 meter: Kane-alert-CO2
· Magnetic Stirrer: Hanna Instruments HI 190M
Note: Water in a sealed container gives 100% humidity, and condensation may eventually damage the electrics of the meters, everything is thoroughly dried at the end of each run.
FURTHER INFORMATION
Readers can follow developments, and make comments, at the following website:
An Ocean Acidification Experiment
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
The world’s oceans hold 1.35 billion cubic kilometers (320 million cubic miles) of water. The average depth is 12,100 feet.
I was taught by one of the best marine chemist at the time (circa 1960s) that the oceans, besides being far larger than most people comprehend, were a strongly buffered system. We had to keep that in mind anytime we were sampling and interpreting the results. Note ocean acidification was been discussed even then, before CAGW arrived, it drove my professor nuts.
I attended foundation lecture for the public on the horrors of climate change causing ocean acidification in a fund raiser attended by several local politicians. We were shown similar experiment on a larger scale with coral added into the bottles. We were shown before and after images of how the coral died when the pH was lowered. During the question and answer section I asked how much they had changed the pH and over what time period and how did that change compare to the possible ocean acidification? I said that corals can likely tolerate a small slow increments but just about anything will die if you dump enough acid on it all at once. The presenting ‘scientist’ got extremely uncomfortable. He literally started shifting his eyes back and forth and then, by his body language, acted like I had caught him out. He said he wasn’t sure because they had done many experiments and he wasn’t sure which experiment matched the images he had shown, and he would have to get back to me on that. I said surely since this was his experiment he could provide an estimate, 1, 2, 3 units? Over a week, a day, an hour? He shifted to but ocean acidification was a very important topic and needed funding for in depth research if we were to save the reefs and blah blah blah never actually answering me. To my surprise, several others including the politicians, picked up on that and spoke to me at the wine and cheese post presentation. Underlings kept trying to insert themselves between me and the politicians. I got a lot of dirty looks. I never heard if he got the money.
The pH scale is log so every whole number is a power/factor of ten.
By definition pH is the negative exponent of the hydrogen ion concentration.
For instance, pH 9 is 10^-9 or 1 part per billion, 0.000000001.
pH 8 is 10^-8 or 10 parts per billion, 0.000000010.
To go from pH 9 to pH 8 is factor of 10 or 1,000%!!!! Makes 26% look trivial.
Ocean “acidification” of pH 8.2 to pH 8.1 is a change in H ions of 1 ppb.
I’m fairly certain the ocean flora and fauna don’t even notice.
Good experiment, but I think too generous to the fruit loops who scream disaster. The atmosphere at sea level is about 1000 times less dense than the ocean, but the ocean has about 1000 times more mass, so their volumes are roughly comparable. Your sea water, then, should be about the same volume as the air above it, but you experiment seems to have much less water than that.
Your results are common sense.
Ocean acidification is, however, only an issue if humans caused the atmospheric CO2 rise. There is observational evidence that atmospheric CO2 is tracking temperature. For that to be true there must be a larger source of CO2 into the biosphere and a larger sink of CO2 out of the biosphere.
New organic sinks of CO2 discovered.
This recent observation that C14 is making to the deepest ocean disproves the CAGW created Bern model of CO2 sinks and sources and resident times.
https://www.livescience.com/65466-bomb-carbon-deepest-ocean-trenches.html
Bomb C14 Found in Ocean Deepest Trenches
‘Bomb Carbon’ from Cold War Nuclear Tests Found in the Ocean’s Deepest Trenches
Bottom feeders
Organic matter in the amphipods’ guts held carbon-14, but the carbon-14 levels in the amphipods’ bodies were much higher. Over time, a diet rich in carbon-14 likely flooded the amphipods’ tissues with bomb carbon, the scientists concluded.
Ocean circulation alone would take centuries to carry bomb carbon to the deep sea. But thanks to the ocean food chain, bomb carbon arrived at the seafloor far sooner than expected, lead study author Ning Wang, a geochemist at the Chinese Academy of Sciences in Guangzhou, said in a statement.
This is an excellent summary of the CO2 resident times and the creation of the Bern model dogma.
https://www.co2web.info/ESEF3VO2.pdf
Thank you so much. A fascinating link . A brilliant history.
What would be the pH if the temperature of the “seawater” was 37 degrees Celsius?
I hypothesise (guess) that it may be around 7.4.
Dr. Michael Chase
Your pH values are on the high side of what is usually reported. Have you given thought to calibrating your instruments?
It is unclear for what purpose this experiment was performed. The dependence of CO2 concentration in water on its partial pressure in air has long been studied, the values of the Henry constant are known:
https://images.search.yahoo.com/search/images;_ylt=A0geKeoWut5cbYsAODBXNyoA;_ylu=X3oDMTByMjB0aG5zBGNvbG8DYmYxBHBvcwMxBHZ0aWQDBHNlYwNzYw–?p=henry+constant+for+co2+in+water+at+different+temperatures+char
Also known is the dissociation constant of carbonic acid in pure water and in an artificial mixture similar to seawater. Knowing the partial pressure of CO2, the temperature and the dissociation constant, one can calculate the pH.
In other words, this experiment could only show how the results for water samples taken “from the shoreline near Weymouth in Dorset” differ from the calculated values. And in order to explain this discrepancy, it is necessary to know, in as much detail as possible, the chemical composition of water, primarily the concentration of carbonate and bicarbonate ions, as well as borates and silicates, which have a buffer effect.
By the way, the concentration of carbonate ions in sea water exceeds the concentration of dissolved CO2 by more than 20 times, and the concentration of hydrogen carbonate ions is greater than the concentration of CO2 by more than 170 times (Table 1.2 on page 26 in http://oceanrep.geomar.de/8471/1/Guide%20best%20practices%202011.pdf )
From this it follows that the increase in CO2 concentration in the atmosphere from 0.03 to 0.04% over the last century should practically not have changed the acidity of the ocean.
While CO2 effects on sea water may have been studied, and you may be able to calculate pH in a “perfect setting”, science is all about measurements. It’s the taking of measurements and then trying to figure out why they do not match theory that leads to important discoveries.
I encourage people to make their own measurements. It might not advance the debate on the effects of atmospheric CO2 on the oceans, but it will advance at least one person’s understanding and might lead to a curious finding.
Suggestion: Try doing the experiment again and add carbonic anhydrase to the solution. You might see a difference at the beginning, depending on various experimental factors.
The experiment reaction rate is more susceptible to mixing rates and other factors than might first appear to be the case. In fact it is sometimes used as an simple undergraduate demonstration experiment where a saturated (with added excess solid CO2) solution containing indicator is neutralized/basified with added sodium hydroxide solution. The color changes immediately upon addition of base and then, after about 10 seconds or so, reverts back to mildly acidic as le Chatelier slowly drives it back again with the excess CO2.
Why would that matter if it doesn’t change the final result? It speeds up the kinetics of the CO2+H2O/H2CO3 exchange over a million-fold. It is thus ubiquitous in nature for obvious reasons, and present in the biofilm covering the surfaces of all water bodies on earth. The rate of this chemical reaction determines how fast oceans can absorb (or expel) carbon dioxide. In the real-world ocean experiment we never get to see the end point, only the beginning of the experiment because oceans are so vast, mixing is relatively slow, and the final equilibrium end-point is never reached.
Any climate model that ignores this factor is probably useless.
Dr. Chase ==> You might want to read the two essays I wrote here some time ago on this topic. A great deal of effort has been put in by a group of OA scientists to change the way OA experimentation was being done and bringing about better and more real, dependable results.
You might review “the European Project on OCean Acidification (EPOCA) – which produced the booklet “Guide to best practices for ocean acidification research and data reporting” .
You guys are something else. Get yourselves a bucket cold water and a heat gun and try putting physical heat through the surface of water. The heat is rejected. Only radiated energy penetrates the surface of water. Have a nice day.
As a chemist, I am outraged at calling a faint neutralization of a mild base “acidification.” That is emotional, like calling climate skeptics “deniers.” High school and college Chemistry class acids are extremely strong and burn a hole in your skin in less than a second if you splash a drop on yourself.
pH of the ocean is 8.1. Your blood is 7.4–so that is likely the ideal for life. Organisms can thrive in an actual acidic environment of say, pH6.
The reason Climatistas use the term “Ocean Acidification” is simply that it sounds so much scarier than “a very slight and probably undetectable decrease in the alkalinity of seawater”.
A few years ago, a commenter posted a very interesting comment/short article on his experiments with “radiative gases” over water. He found enhanced cooling. Since 3/4 of Earth’s surface is ocean, this suggested a net cooling effect of CO2.
I tried to verify that using ordinary glass oven pan–and found too much of a breeze at all times. I calculated that even a very slow zephyr of 1 mile an hour, 5280 feet, divided by 3600 seconds per hour came to over a foot a second–can’t get a practical reading outdoors. For you metric people, there is usually at least half a meter a second or more wind speed outdoors.
Your equipment, used indoors, with a window for sunshine, might be usable to find out more about this.
This is silly. It’s like two guys with a bottle of CO2 trying to show global warming.
The systems involved in real life are ridiculously complex and to bother with this type of home experiment is ridiculous.
More useful would be lots of reporting on pH around the oceans under various conditions showing what a wide variety of pH exist on an hourly basis. WUWT had an article that reported on pH fluctuations by the hour around some reefs which should have made everyone who claims the reef will be destroyed by a small fluctuation sit up and say “Oh, I didn’t know that”.
This is an interesting first-approximation experiment, but it’s not very realistic. As some commenters have noted, what about the effects of photosynthetic organisms (plankton or seaweed) which could be absorbing CO2? Also, in shallow sea water, there are many reactions between bicarbonate or carbonate ions with dissolved calcium salts, which can be taken up by mollusks and used in their shells. It would be a good idea to repeat this experiment with a sealed salt-water aquarium whose temperature could be regulated, which includes some photosynthetic organisms and mollusks and (why not?) fish.
Such an experiment would not adequately model deep-water areas (> 100 meters) of the ocean. There would still be phytoplankton in the surface layer, but any excess carbonates could be precipitated out as calcium carbonate and drop to the bottom, so that the deep oceans would be a huge sink for CO2 during cooler weather (at night, or during winter in temperate areas) when CO2 is more soluble in sea water. It would take a long time to precipitate all the calcium salts out of the oceans!
While a noble effort to document the sensitivity (or lack thereof) of seawater pH to CO2, the values you obtained indicate a serious flaw somewhere in your experiment. Using the well documented thermodynamic equations to calculate the rest of the carbonate system (alkalinity, total dissolved inorganic carbon, etc), and assuming your salinity was 32, temp around 13, and operating at surface pressures suggests that your total alkalinity is between 16,000 to 23,000 micromoles per KG of seawater. This is roughly 10x higher than nearly all measurements ever made of surface seawater (it is far outside the realm of even plausible). Your experiments are essentially violating some basic fundamentals of thermodynamics if your numbers are in fact correct and real.
There are two possible explanations for this, first is your 2L jar or seawater sample was contaminated by the baking soda you used in some way, or second that either (both) of the instruments you are using are incorrect. Did you calibrate either of them to ensure the values are correct? with at least a 2 point calibration to ensure appropriate responses? Also, a pH of 8.8 would be a very unusual value for seawater (but far more possible than the computed alkalinity values). What time of year and time of day was your seawater collected as this would allow others to see if perhaps local photosynthesis may be able to explain the very high pH (it would not be able to explain the alkalinity though). It is important to note that a resolution of 0.01 pH units does not mean an accuracy or precision of similar magnitude.
You can download the software for the calculations here:
https://www.usgs.gov/software/co2calc
And might I suggest a very good reference book on marine carbonate chemistry by Zeebe and Wolf-Gladrow called “CO2 in Seawater: Equilibrium, Kinetics, and Isotopes”.
Finally, just one correction on the statement about pH changes being less at lower pH, this is actually opposite. As more CO2 is added to seawater the change per unit added becomes greater because the solution has less ability to absorb that CO2 into the acid-base system (due to the consumption of carbonate ions via carbonic acid dissociation). The Revelle Factor is the index used to determine how sensitive the carbonate chemistry is to increases in CO2.
cheers
george
https://lnkd.in/ep3BvYJ
Dr. Raveendran Narayanan USA :-
Since 1980 Oceans and Seas pH never ever came below pH 8.00.
IPCC needs $122 TRILLION for Climate Correction, BUT not C02 and GHG.
3° C Temperature REDUCTION is possible by errecting ZERO DISCHARGE SYSTEMS in DESALINATION plants. The Mother Earth can be AIR CONDITIONED WITHOUT A DOLLAR.
https://lnkd.in/erZHg3W ” NOMINATE FOR NOBEL PEACE PRIZE 🏆 2019″
“ONE SHOT MANY BIRDS” : http://wp.me/p25H2W-dB via @Raveendrannaray.
—->>>>> 3° C TEMPERATURE REDUCTION IS POSSIBLE + NO MORE ESCAPING OF METHANE FROM ICE SHELVES + NO MORE OZONE HOLES + NO MORE SEA RISE + NOT MUCH STRONGER HURRICANES + NOT MUCH CALAMITIES+ NO MORE EXTREME WEATHER + PLENTY OF DRINKING WATER FROM SEA WATE R + MORE FOOD & VEGGIES + WORLD ECONOMY WILL BE GOOD –>>>>> ” AIR CONDITIONING OF MOTHER EARTH”
#youtube #climatechange #globalwarming #noozoneholes #rewritingearthscience #notco2 #2019earthsciencecommettee
#airconditioningthemotherearth
#cop24 #unfcc #ipcc #epa #timemagazine
#challengingexpertglaciologists
#1000ppmco2noproblem #cop25 #chile2019 #environmentalprotection
#challengingipcc #stoppingcalamites
http://raveendran_narayanan@airconditioningthemotherearth.com
One important detail is not explained here: is the air levels of co2 kept constant during the experiment, or is it only the initial level?
Although simple, this experiment demonstrates to a general audience that even partial pressures of CO2 much larger than atmospheric levels will probably have a small effect on ocean pH. The ocean will continue to be alkaline for the foreseeable future.
Measurements from Hawaii and Bermuda show that the ph in Ocean surface water has decreased by approximately 0.04 since 1990ph readings from Hawaii and Bermuda
/Jan
/Jan
Sorry for error in link, hope this work:
Measurements from Hawaii and Bermuda show that the ph in Ocean surface water has decreased by approximately 0.04 since 1990 ph readings from Hawaii and Bermuda
/Jan
Many Decades go I was taught in level 2 physical chemistry that glass electrode pH meters cannot measure pH if the salt concentration exceeded 0.1 mol/litre.
As sea water is higher than this could you comment on the reliability of your findings ?
Second issue: we are talking here of an equilibrium for the equation:
CO2 (aq) + 2H2O = HCO3 + H30 (Sorry cannot do the charge signs, just take them as read)
Being an equilibrium, the reaction would go in reverse and increase the CO2 if the hydronium ion concentration got too high.
At the end of the day the CO2 in the atmosphere is determined by temperature of the ocean and the state of the equilibrium between these compounds (plus carbonate) Not by the puny amount that humans add to the atmosphere
Bear in mind that bicarbonate concentration in sea water is 100 times that of CO2 (aq)