What is ocean acidification and why is it important? Let’s start by looking at the pH scale, and where the ocean currently sits upon it. The pH scale is a measure of the acidity, or alkalinity of a substance (usually a fluid) - in this case the ocean. The scale runs from 1 to 14, with any reading below 7 considered to be acidic, while any reading above 7 is considered to be alkaline. A reading of 7 is considered neutral – neither acidic or alkaline. The pH reading is dependant on water chemistry, particularly the ions present in the water. An excess of H+ ions will cause acidity, and excess of OH- ions will create alkaline conditions. But how does this happen and why is it important?
Firstly, the Ocean is slightly alkaline – currently sitting at 8.1 on the pH scale. Before the industrial revolution began (around 250 years ago) the ocean was slightly more alkaline, sitting at a pH of 8.2. So what has changed? The burning of fossil fuels has added an enormous amount of carbon dioxide (CO2) into the atmosphere, and while this has impacted global warming and climate change, it has also affected the pH of the ocean. Carbon dioxide reacts with seawater to produce carbonic acid (H2CO3). So an increase in carbon dioxide leads to an increase in carbonic acid in the world's oceans, and this process is known as ocean acidification. You may wonder why this is a problem. Well, sea creatures like snails, mussels, oysters, limpets, barnacles and periwinkles all have shells made of calcium carbonate – even coral skeletons are made of this. Calcium carbonate requires an alkaline environment to be built and remain strong. Any reduction in alkalinity (or increase in acidity) weakens calcium carbonate, putting all of the sea creatures who depend on it at great risk.
You can see this at work by putting a few seashells in vinegar and watching what happens. Vinegar is a highly acidic liquid, and calcium carbonate will fizz and bubble when placed in it and eventually dissolve away or crumble apart.
The more carbon dioxide we humans put into the atmosphere, the more carbonic acid will be produced in our oceans, so to save an extremely important part of the ocean ecosystem, it’s critical for us to do what we can to reduce carbon emissions – and we can all do our part! Find out how you can help to save the world’s oceans and reduce your ‘carbon footprint’ here.
Comments