Is the ocean turning into an acid pit? Is it a corrosive as a battery? No! This is a common misconception and a question that our student stewards often bring up during our hydrology lessons. What influences the pH in the ocean? The ocean has had fairly steady pH levels for millions of years, thanks to a buffering system. The term “ocean acidification” is a relatively new word for a well-known processes. The ocean has long been slightly basic, and ocean acidification is causing it to be slightly less basic (closer to neutral).
The pH scale shows the proportion hydrogen ions are in a solution. This scale is from 0 (acidic) to 14 (basic). Neutral is 7.
A buffer system is a series of reactions that break apart and form molecules that keeps the level of H+ protons (pH) constant. There are many types of buffers used in various reactions (even in hottubs), but in the ocean, the most prevalent system is the carbonate buffer system.
Carbon dioxide (CO2) is a very important factor in ocean pH. Sources of CO2 include combustion (volcanoes, also the burning of fossil fuels), respiration, and chemical reactions. An increase CO2 has begun to “overwhelm” the buffer system, which cannot replenish carbonate, and which is not removing hydrogen protons quickly enough to keep up with the absorption of CO2.
It is important to know that in the carbonate buffer system, carbonate ions are consumed to buffer against pH changes. Carbonate ions are also needed by many animals to create shells and skeletons—with an increase of CO2, more carbonate ions are used for buffering, and less is available for these animals.
What can a steward do? With an understanding of sources and sinks of carbon, we can make daily choices to reduce our carbon footprint, and to increase our positive impact. CO2 comes from respiration, chemical reactions, and combustion. Combustion is a huge source of human-made CO2. “Spare the Air” days target combustion by encouraging people to reduce their driving, and banning burning firewood. Biking to work, riding public transportation, carpooling, and choosing products that haven’t been driven or flown from far away, are great actions that individuals can take. Plants absorb CO2, so just by tending your garden, you are helping!
- National Geographic: Ocean Acidification
- NOAA: What is Ocean Acidification?
- NASA Educational Workshop: The Basics of Ocean Chemistry: Carbon, Circulation, and Critters
- NIWA: What is Ocean Acidification?