ABSTRACT
The pH scale is a measure of the acidity of a liquid, with acids having a value lower than 7, and alkalis higher than 7. The pH scale is logarithmic so that a decrease of one unit represents an increase in acidity of 10 times; hence, fizzy drinks are about 10 times more acidic than tomato juice, and lemon juice 10 times less acidic than car battery acid. Seawater has a pH above 7 because of the solids that are contained within it. Since the Industrial Revolution, the amount of carbon dioxide has increased in the atmosphere, and about 25% of the CO2 is removed from the air and absorbed by the top layer of the oceans. The shells of molluscs, the skeleton of corals and the exoskeleton of some algae are all impacted adversely by the increasing amounts of CO2 being absorbed by the oceans. Although this process is referred to as acidification, seawater is not actually acidic.
