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Ocean acidification explained with dry ice

Dear imaginary readers,

It took ages for me to write a post as I am about to embark in a very exciting new adventure in the very near future.

I wanted to write this post straight after I was back from Into the blue in Manchester last October, but my worst enemy, the God of Postponing won the battle.

If you remember I was there with the Environmental Chemistry Group of the Royal Society of Chemistry working as a volunteer to introduce the public to the real problems the environmental chemists work on.

We had three stalls with different “hands on” interactive activities for kids (even though adults seemed to enjoy as well).

The first and the second were about environmental pollution, with a tray full of soil and small pieces of plastic dispersed in it and simple nitrates and phosphates testing kits.

into the blue 2

The real queen of the activities we proposed was the ocean acidification demonstration. It does involve smoke and colour changes so it does automatically attract the public attention.

In the rest of the article you can find the procedure, materials and adaptations you can use to realize the experiments in secondary schools, lab or even in the streets, as we did!

First of all we assessed what the audit knows about pH, asking questions and showing a pH colour scale. Then we encourage people to test different thing like drinking water, “fake” pre-made ocean water (pH about 8.2, adjusted with NaOH), coke, orange juice, milk and soap solution with bromothymol blue, litmus paper or any other pH indicator.

Ask the spectators if they know where seawater fits in on the spectrum. Explain that pH is measured on a logarithmic scale like earthquakes and a small change in pH from 8.2 to 8.1 corresponds to an increase in acidity of about 30%.

For this activity, the audience should understand that when humans release carbon dioxide into the atmosphere by burning fossil fuels, some of the carbon dioxide is absorbed by the ocean. This changes the chemistry of seawater making it more acidic. About one third of the carbon dioxide released into the atmosphere over the past 200 years has been taken up by the ocean.

Then we started to explain why ocean acidification is a current and future problem. The average coastal ocean pH is 8.2, but it is changing because of the addition of carbon dioxide to the atmosphere and the subsequent absorption of that carbon dioxide into the ocean. About 30% of the carbon dioxide produced daily is absorbed by the ocean. The pH of the ocean has decreased 0.1 in the last century; it is becoming more acidic (less basic). Some of the organisms at greatest risk include larva and shell-forming animals at the base of the food web that provide food for larger species. Organisms faced with the stress of ocean acidification can migrate, acclimate or go extinct and values of 7.8 are expected by 2100 for the average ocean water, representing a doubling of acidity. Additional stressors that increase the impact include temperature increase and habitat loss.

Then you show the spectators the dry ice in a watch glass pointing out that is the solid form of CO2 and that is changing to a gas (sublimation) at room temperature, so its temperature is about -78 C so they should never touch it with bare hands. When it is added to water it rapidly changes to the gas form and some of this gas becomes dissolved in the water.

We then added enough dry ice to a conical flask containing the “ocean water” and bromothymol blue and the solution will turn progressively yellow as the pH decreases because of the formation of carbonic acid that acidifies the solution.

Because of the quick reaction and the big temperature difference between the “sea water” and the dry ice there will be quite a bit of what looks like smoke or fog billow away from the conical flask (it is actually vapour). The kids will go really excited (some of them even scared) and you will definitely get some “oooooooooooooooh”.



When the reaction has finished and the spectators have regained their concentration, we tried to recap what they saw and why it matters to the ocean’s environment. Adding carbon dioxide to water makes it more acidic or less basic. This is what is happening to the ocean. Humans add carbon dioxide to the atmosphere by burning fossil fuels (driving cars, creating electricity, etc), deforestation, and in many other ways. The ocean then absorbs some of what gets emitted into the atmosphere, sometimes we say that the ocean acts as a “sink” for carbon dioxide. This effect is worsened by the global warming of the planet. The change in the chemical average composition of the ocean’s water, have consequences on many marine creatures, such as shell forming organisms such a corals, bivalves (clams, mussels and oysters) and pteropods (free swimming snails) that are sensitive to changes in pH.

If you want to do this demo as part of a wider lesson in schools, you can add a detailed explanation of the different reactions the CO2 gives in different environments and related demonstrations (acidic rain, weathering of rocks, cave formation)

For the ocean acidification the chemical reaction is the following.

CO2 + H2O      →        H2CO3

As shown in the chemical reaction scheme, when carbon dioxide (CO2) dissolves in seawater, it creates carbonic acid, which releases bicarbonate ions (HCO3-) and hydrogen (H+) ions into the water. The hydrogen ions make the seawater more acidic (lowering its pH). In addition, some of the hydrogen ions react with carbonate ions (CO3=) already in the seawater to create more bicarbonate. This reduces the amount of carbonate (an important mineral for building shells) dissolved in the seawater. The impacts of ocean acidification and lower carbonate ion concentrations on marine ecosystems include reduced growth of organisms that form calcareous skeletons or shells.

Ocean acidification and global warming are relegated to the science fiction shelves by one of the more powerful politician of the world, at a point in the life of our planet when the consequences of the increase of CO2 released into the atmosphere are about to spiral up culminating in a very hostile environment for humans and every other living thing.

For this reason is more important than ever to engage in outreach activities trying to explain to as much person as possible that our choices have a very big and dangerous impact on the place where we live, and that it is important to act on a personal and a political basis.

Time is now!

“I think that once people understand the great risks that climate change poses, they will naturally want to choose products and services that cause little or no emissions of greenhouse gases, which means ‘low-carbon consumption.’ This will apply across the board, including electricity, heating, transport and food.” Nicholas Stern, IG Patel Professor of Economics and Government, Chairman of the Grantham Research Institute on Climate Change and the Environment and Head of the India Observatory at the London School of Economics.

Have a lovely end of summer everyone, but always try to be conscious! Hasta la vista




Science drawings at the Royal Society

If you think about a modern scientist doing his job, you will probably imagine him/her operating complex and expensive cutting edge machines and computers, characterizing materials and structures through a SEM, and producing and disseminating evidences to support their theories and express their results in form of pictures, graphs and images obtained using sophisticated digital cameras and manipulated with innovative softwares. There is a good chance they will use a laser or, even better, a 3D printer.

For the youngest audiences in particular, it is very difficult to imagine that there was a time, when a scientist had to be good at drawing, or at least at finding someone able to do it in his place.

Early biologist, botanists, ethologists, and even chemists, were forced to use their artistic skills to understand and explain the rules of the world that they were trying to unlock. Some of them weren’t so scientific, in a modern sense, at the contrary their works are very imaginative, but they are still interesting, as the following books illustrations.

An image of the human forms (“The pearl of philosophy”) by Gregorius Reish, 1508. The book is a encyclopedic compendium of contemporary knowledge written for university students. Gregor (Gregorius) Reish (1467-1525) was a Carthusian monk and teacher.
A traveller surprised by a dragon. Illustration from “Helveticus Itinera Alpina tria…” by Johan Jakob Scheuczer 1723. In this book Swiss naturalist Scheuchzer (1672-1733) gives an account of his travels in the Swiss Alps and recounts tales of reported sightings of dragon-like creatures supposedly encountered by travellers.
A “dragon” made from fish parts. Illustration from “Serpentum et draconum historie (History of serpents and dragons)” by Ulisse Aldrovandi, 1640. In his book, Aldrovandi, provided detailed descriptions of real snakes while debunking fake “monsters” stiched together from other animal parts.

The changes in the way scientists produce images and share them within their community and the public, was the subject of a day of hands on activities and lecture at the Royal Society, last Saturday, the 25th of October. The title of the event was “The Big Draw: Drawing Science” and was part as The Big Draw festival,

Young children, and curious adults as me, were “pushed” to take inspiration from rare scientific illustrations pulled from the Royal Society archives, exploring areas where science and art overlap.

Illustration of grief from “The Expressions of the Emotions in Man and Animals” by Charles Darwin 1872. In this book, Darwin attempts to trace the animal origins of human characteristic and emotions including grief, anxiety, joy and despair.
Specimens of foraminifera (single celled marine organisms with shells) by Henry Bowman Brady (1835-1891), naturalist and pharmacist.
Lacerta gecko by William Clift, 1816. Illustration produced for the paper “Some account of the feet of those animals whose progressive motion can be carried on in opposition to gravity”, by Everard Home, Philosophical Transactions of the Royal Society vol 106 (1816) pp 149-155. The Lizard specimen was procured by Sir Joseph Banks, apparently from Java.
Spectra from light shone trough prisms. Optical diagrams showing light shone trough prisms and the resulting optical spectral patterns. Plate from the monograph: “Merkwurdige phanomene an und durch verschiedene prismen: zur richtigen wurdigung der Newton’schen und der von Goethe’schen farbenlehre (remarkable phenomena at and trough different prisms to correct Newton’s and Goethe’s theories of colours)” by Johann Friedrich Christian Werneburg (Nurember, 1817).
Hummingbirds, by William Matthew Hart, 1887. “Helianthea Osculans” Buff-tailed Starfrontllet (left) and 2Heliodoxa Xanthogonys” Guiana brilliant (right). Illustration from “A monograph of the Trochilidoe, or family of hummingbirds: supplement…completed after the athors death”, by Bowdler Shape, part V (London 1887). The posthumous supplement to Gould’s 1861 monograph of hummingbirds.
Observations of aphids, and a glass bead microscopes, by Antoni van Leeuwenhook (1632-1723). A red chalk drawing wich accompanied a letter sent to the Royal Society on the 26 October 1700, containing notes on insects observed by Dutch microscopist Antoni van Leeuwenhook. Leeuwenhook investigated the structure of muscles and plants; the shape of crystals in grains of sand and much more. He was the first to describe microscopic organism living in water. We know them today as bacteria and protozoa. A replica single lens microscope, of the tipe developed by Leeuwenhook. The instrument’s small lens could magnify up to 250 times.

In addition to the importance that science illustrations have in documenting the path and development of some of the most important scientific discoveries and theories, they also suggest the hypothesis that drawing complex natural structure precisely, may help to better understand the details, and how they are related and interconnected to each other, forming a whole. In other words, producing your own images you will learn more about what you are studying.


A bean sprouting, by Marcello Malpighi FRS (1628-1694). This read chalk drawing shows the life a bean from germination to a seedling and features in Malpighi’s manuscript “Anatome Plantarum”, 1675. Malpighi was a physician and experimental biologist. Along with his contemporaries Robert Hooke and Antoni van Leeuwenhook, he was a pioneer of the microscope.
Ammonite and other fossils. Illustrations in the “Posthumous works of Robert Hooke” edited by Richard Waller, 1705. Robert Hooke FRS (1635-1703) natural philosopher, architect and polymath, was the Royal Society’s first curator of experiments.
Letters to the Royal Society, by Sir Isaac newton (1642-1727). Newton began to write to the Royal Society in 1672 outlining the main result of his optical experiments. These included his work on light and colours published in the “Philosophica Transactions” and this original drawing of the reflecting telescope.

Because children like drawing, involving them in making their own scientific illustration, copying original drawings, complete animals half drawn, or building mosaics with the basic crystals shapes, can be both educational and fun!

Children and their carers enjoyed a dedicated area with activities and workshops, try their hands at drawing animals, making their on pop-up book, or having a dinosaur named after them.

Personally, I found the activities very interesting and it would be a good idea to carried them out in a school, to be used in support to the science curriculum or during after school or summer club.

James Mckay is a UK based illustrator, writer and designer, who entertained the kids and made personalised fantastic dinosaurs.
One of the fantastic dinosaur created by James Mckay.
One of the children works of art inspired by the material of the exhibition and the histories told by the experts.

During the afternoon two lectures took place, in one of the beautiful rooms of the Carlton House Terrace.

The first one was lead by historian Dr Sachiko Kusukawa, tutor and Fellow in the History and Philosophy of Science at the University of Cambridge.

The focus of the speech was on the intersections of art and science in the 17th and 18th centuries. Professor Kusukawa explored sketches, engraving and paintings that gave background to some of the images on display, and explained how they were used by scientist to guide their studies.

The second lecture, was more informal, and I really enjoyed it. The title was “Dynamic collaborations”, and was lead by Brian Sutton, crystallographer and professor of Molecular Biophysics at the King’s College of London, and glass artist Shelley James, originally trained in textiles, at the Ecole Nationale Superieure des Arts Decoratifs in Paris and then deciding to explore the themes of perception and reality from a more personal perspective, she studied printmaking at the University of the West of England. This lead to developing new techniques for encapsulating prints in glass with support from the National Glass Centre in Sunderland and Arts Council England. The symmetry and quasi-symmetry of crystals inspired Shelley to produce her 2D and 3D glass works. Professor Sutton and Shelley engaged the public with a conversation about how they ended up working together and what the differences and similarities in their vision of crystals are.

Shelley James during her speech with some of the models she uses to get inspired.
Shelley James 1
Essential Symmetry serie: Truncated Octahedron. In Greek philosophy the Octahedron is associated with the air element. Shelley James/blown by James Devereux and Kate Huskie. June 2014, hot glass and print. Image by Ester Segarra c2014

In a passionate and inspiring explanation professor Sutton told us the story of the Penroses tyles and the discover of a very special type of minerals that lead to a very important Nobel price for Chemistry in 2011 . In fact in 1984 the team of Professor Schechtman found that a crystal of a rapidly cooled alloy of aluminum and manganese,  was showing a 5 fold  symmetry (the so called “forbidden symmetry”). The team’s description of the atomic structure of a metal alloy ultimately forced scientists to redefine the term “crystal.”

The 2011 Nobel Prize in Chemistry recognizes the discovery of quasicrystals, in which atoms are ordered over long distances but not in the periodically repeating arrangement of traditional crystals.

A new category of crystals whose patterns don’t repeat in the traditional way.

Nature never stops to surprise us!