Ocean Acidification June 3rd | 页面 2

What is Ocean Acidification?

Ocean acidification means a decrease in the pH levels of our oceans. Although confusing a drop in pH level actual means an increase in acidity because of the way the pH scale is set up. To clarify, pH is set up on a scale that ranges from 1 to 14; 1 being extremely acidic, 14 being extremely basic, and 7 (directly in the center of the scale) being neutral. Another common misnomer associated with ocean acidification is that ocean water is becoming acidic, meaning a pH lower than 7. This is not true; ocean pH will never actually drop below 7 (McAuliffe, 2008).

Nitty Gritty The Chemistry of Ocean Acidification

Ocean Acidification is caused by oceanic absorption of CO2 (Rio+20 Ocean, n.d.). In fact, the ocean absorbs 25-30% of all atmospheric CO2 (Rio+20 Ocean, n.d.). The following process is the chemistry behind how this is done. (NRDC, n.d.)

Step 1: Atmospheric CO2 molecules are absorbed into the ocean

Step 2: They react with H20 molecules to form H2CO3, carbonic acid

Step 3: The formation of carbonic acid creates a free hydrogen ion (H+)

that reacts with carbonate ions to form bicarbonate .

This effectively removes lowers pH levels as well as lowering carbonate ions. Read about why this is bad on the next page.

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http://www.nrdc.org/oceans/acidification/images/chemistry-basics.jpg

8.1, Modern Day pH (NOAA, 2015)

Not-so-fun fact

The ocean has

absorbed 560 billion tons of CO2 in the past 250 years .