Stewardship Monday: Acid Ocean?

As discussed in last week’s post, the ocean is an important “sink” for the greenhouse gas, CO2 (carbon dioxide). Unfortunately, increases of this gas affect more than the atmosphere; it is linked to “ocean acidification”. Does this mean the ocean is turning into battery acid? No! The ocean is actually alkaline (basic). That means on the pH scale 0-14, where water is 7 “neutral”, the ocean today is on average, 8.1—which is 0.1 more acidic than it was two centuries ago (8.2). So the term “ocean acidification” is referring this drop in alkalinity.

The ocean is a fantastic buffer. That means that there are chemical processes that take place to minimize changes in pH, which are caused by amount of hydrogen atoms (H+). Buffers are very important because many biological processes are sensitive to pH and even a 0.1 change in pH (on average) can represent a huge shift in functions for animals that live in the ocean.

The basics of acidification:

  1. When the ocean absorbs CO2, water molecules combine with it to create carbonic acid (H2CO3).
  2. Carbonic acid then breaks down into hydrogen atoms (which decrease pH, or make it more acidic) and bicarbonate ions.
  3. The extra hydrogen ions react with carbonate ions (CO3) to form bicarbonate.

For a free classroom unit with activities that demonstrate this effect, visit: Division of Earth and Life Studies of the national Academies by clicking the picture below:

 Marine species that build shells or exoskeletons combine carbonate ions with calcium ions to create their calcium carbonate homes. The extra hydrogen “takes up” some of these carbonate ions, so there is less building materials for them unless they have special adaptations to deal with this influx of ions.

In addition to hindering the building of shells, acidity dissolves existing shell material, further weakening shelled animals.

photo credit: http://www.hnc.org

What does this mean for us? This is a global issue that will have wide reaching affects. For example, oyster farming is an important food industry that has already felt the affects of changing water conditions. Beyond affecting animals that we directly eat, this change in water chemistry will affect the entire food web, harming the crustaceans and mollusks that feed larger fish that humans consume. Because some animals are more sensitive than others, we may also see a dramatic change in ocean ecosystems and communities.

What can we do?

Recent reports show that if all human carbon emissions stop today the effects of climate change will still be felt for generations to come. However, if they continue unabated, the affects will be orders of magnitude more powerful. So as stewards we can do our part by making choices to reduce greenhouse gas emissions, and support sequestration (taking up) of carbon.

Visit the carbon footprint calculator linked on the first Stewardship Monday this month to see what your impact is. With this information you may be able to identify carbon sources that you can avoid or reduce in your daily routine. I’ll admit, I used a plastic Tupperware for lunch today; to minimize my impact I will reuse this as long as I can, and next time I will choose a container that lasts longer and has a lower impact.

These are some other things that I will try to do to reduce my carbon output this week:

  • walk to the local grocery store and buy local produce
  • make sure I turn the lights off when I leave the room
  • unplug my phone charger when not in use
  • make sure that the insulation on my home is good as the weather gets colder
  • wear a sweater at home and turn down the heater by a couple degrees

What small changes (or big changes) can you make to reduce your impact?

 

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