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A fantastic Ocean and Earth Day at National Oceanography Centre

09 April 2013


Blowing through the straw in a cabbage juice. Image courtesy of Barry MarshAnother successful Ocean and Earth Open Day was held at the National Oceangraphy Centre (Southampton) on Saturday 23rd March 2013. A great turn out on a very cold day, they had over 3000 visitors attending the event and the feedback was extremely positive.

The Sea Surface Ocean Acidification consortium (@surfaceoa) participated in the event with a poster display and information material about their research on ocean acidification and its impacts on marine life and ecosystem processes.

A key feature of the stand was a simple experiment; a safe and easy way to show to children what their breath can do to a natural and easy-to-make acid/base indicator.

The star of the show was some red cabbage juice. A very small volume of the cooled juice was poured into test tubes and children were asked to blow through a drinking straw repeatedly for a few minutes until they could see the cabbage juice turn noticeably pinker that the juice in the bottle.

What happened? The carbon dioxide (CO2) in the breath combined with the water in the cabbage juice (cabbage is an acid indicator) to form carbonic acid, causing the pH of the solution to drop and the cabbage juice to turn pink.

Why this is interesting? About a quarter of the CO2 emitted by activities, such as burning fossils fuels, is absorbed by oceans and as a result the ocean weater becomes more acidic, like the cabbage juice in the experiment.

The simple experiment was particularly successful; the children and some of the parents too, had a lot of fun blowing into the cabbage juice and after the experiment they commented that they now have a better understanding of what ocean acidification is and why it is important.