Lessons in Cleanliness
The Revelle passed through the Kerguelen Plateau today, a Southern Ocean landmark of several qualifications. For one, this underwater feature extends from one of the only island clusters in this vast expanse of open ocean, the Kerguelen Islands, which happens to include Heard Island, a strictly regulated marine protected area and natural heritage site owned by Australia. If you do in fact wish to visit this island, take care to diligently study the “Environmental Code of Conduct for Visitors to Heard Island” before setting foot.
From an academic standpoint, the waters above the Kerguelen Plateau are a landmark for being one of the unique iron-rich areas of the Southern Ocean. Iron in the ocean is like gold on land: it is scarce, but it is valuable.
The reason, like most reasons in my field, comes down to the base of the marine food chain: phytoplankton. Like plants, these ocean surface critters manufacture organic matter from sunlight and carbon dioxide through photosynthesis. Just as we are told as youngsters that the iron in green vegetables makes us strong, this same element is vital to phytoplankton, as well. Especially in this part of the ocean, scientists believe that iron that is the ultimate nutrient for phytoplankton; it is the prized ingredient that makes them grow, produce and prosper. And it is this prized ingredient that generates particles of organic matter in seawater, waiting to be collected by eager scientists like us.
For all the attention it gets, iron is actually very dilute in the ocean. While the Kerguelen Plateau is considered to be rich in iron, it only exists in trace amounts. The iron in our blood and the iron virtually everywhere on this ship are likely more concentrated than what you’d find in most parts of the ocean. This presents one massive problem for trace metal oceanographers: how to prevent the small amounts of iron in collected seawater from getting contaminated with everything else on this ship.
On the Revelle, the triumphant answer is the “clean bubble,” a special space used just to process trace iron from the sea. When moving onto the ship, I was surprised by how much it was a literal bubble, as opposed to a figurative bubble. The clean bubble was constructed by the six trace metal reps on this vessel: Phoebe Lam, Dan Ohnemus, Ben Twining, Angel Ruacho, Sara Rauschenberg, and myself (kind of). The process of construction starts with an ordinary, iron-laden room and transforms it into a room-within-a-room with the following clean features: contact paper lining every desktop and shelf, walls of plastic sheeting, a HEPA blower ejecting all dirty particles from the air, and finally, special slippers to ensure only the cleanest walkers inside. It is here in this bubble that one may measure ocean iron with a clear conscience.