Beyond the aquarium
The point of the class, however, isn’t solely to learn how to take care of cool animals. The students get a glimpse into how concepts they learn in class might apply to real-life problems: For example, how might scientists approach the dropping pH in the world’s oceans? Over the past 200 years, ocean pH has decreased from a pH of 8.2 to 8.1. This sounds like a small difference, but because the pH scale is logarithmic, a drop of 0.1 pH units represents a change in hydrogen ion concentration from 6 x 10-9 M to 8 x 10-9 M.
Like the students in Christian’s class, some scientists have asked: What can be added to the ocean to keep its pH balanced?
Researchers have floated several ideas to reduce the ocean’s CO2—and its acidifying effect—including adding things to it, such as limestone (CaCO3), other minerals, or iron (“iron fertilization”). Limestone and other minerals dissolve and consume CO2. The idea behind iron fertilization—also called iron dumping—is that iron, an important nutrient to phytoplankton, would fuel a boom in the organisms’ growth. Phytoplankton, which are microscopic marine algae, consume CO2 through photosynthesis to produce glucose, removing CO2 from the water.
6 CO2 + 6 H2O + Sunlight ⟶ C6H12O6 + 6 O2
But there are concerns that adding tremendous amounts of minerals or iron to make a measurable difference on ocean CO2 concentration would require too much energy or have unwanted side effects.
A much lower-risk approach to lowering ocean CO2—at least along coastlines—involves planting seagrasses, which like phytoplankton use CO2 for photosynthesis.
Natural beds of some of these plants have been deteriorating over recent decades due to water pollution. Restoring them would not only serve to remove CO2 from local waters, but it would also bring back essential habitats for other sea life.