Kati points out some of the first pieces of floating sea ice sighted on our cruise. Photo by Brett Longworth
My name is Kati Gosnell and I’m a graduate student in the Florida State University Oceanography Department, studying chemical oceanography. Currently trucking through my second year in the department, I’m working under the guidance of Dr. William Landing. My focus is in trace metals, so I get to clean a lot of bottles.
There is a lot of trace metal action going on in my little world aboard the Research Vessel Roger Revelle. For this research cruise I am helping to sample for iron in the ocean as well as atmospheric deposition levels.
Iron has been determined to be an essential nutrient in the ocean; phytoplankton cannot live and grow without it. Phytoplankton are an important base in the oceanic food chain, so without their blooming abundance, the rest of life in the fathoms of the deep blue is not as prolific.
It’s therefore important to know the sources and levels of iron in the water column. One source of iron is through dust, transported in aerosols (tiny airborne particles or droplets) and dust storms. Much dust is transported out over the Atlantic Ocean from the Sahara Desert.
Over geological time windblown Saharan dust has left a bold signature in the form of extensive sedimentary iron-bearing deposits on the Atlantic seafloor. While oceanographers are keenly aware of this transport and the resulting geological signatures, the general public is not. Asian deserts are also a major source of dust undergoing aeolian, or windborne, transport toward distant locales.
In order to figure out how much iron (in addition to numerous other trace metals) is deposited down here, as well as potential sources, we have set up an aerosol sample collection tower on an upper deck (03) to receive a clean shot of fresh aerosols when the wind is just right. The aerosol tower is located approximately 57' off the waterline, which would be about 18 or 19 meters up there, depending on how the ship is riding the swell.
Aerosol collection tower in a blitz of sea-spray. Photo by Kati Gosnell
Outreach coordinator’s note: Our only photo of the entire aerosol sample collection tower (left foreground with orange flags running up to it) shows the ship’s bow ploughing through stormy seas. Spray kicks up as the bow cleaves each oncoming wave, pelting and spattering the windows that wrap 360° around the ship’s bridge.
We take all the samples we collect back to Florida and measure them in a clean lab while wearing booties and bunny suits.
Zinc is also important to life in the ocean (although not nearly as well known as iron). Zinc is an interesting element since it acts as a double agent working to aid life as a nanonutrient (present in only very minute amounts), or potentially toxic if more concentrated. Our second mission in this adventure is to get a shipboard system going for measuring zinc while out at sea.
Sampling water and taking it back with you to measure in a lab requires a lot of space and airfreight time and expense, as well as running a further risk of contamination through handling. So if we could get a clean and efficient method of sampling zinc while at the source of our sampling, it would be just swell.
Trace-metals clean working space set up in shipboard lab space. Photo by Kati Gosnell
On top of all that we are also taking rain samples to further determine what is swirling around in the atmosphere down here. Rain samples are analyzed for numerous trace metals, but this time we have set up our samples for a special bonus measurement. I plan on taking the rain samples back to the clean lab and measuring the rainwater for mercury deposition as well.
Mercury in high concentrations causes brain impairment, memory lapses and poor health in general. It is not an element you want loaded up in the oceans. It is expected that levels should be pretty minimal down here since there are few pollution sources, but if not, then it will be good to try to figure out what’s bringing it here.
Our first week at sea was pretty chaotic. We had a blast of several stations to sample right out of the gate the first week, so that was about all I did was perform casts and sample. I have had better weeks in my life than that first one.
The second week was much better. Right out of the starting blocks we were visited by a couple of fin whales curious about the funny package we were yo-yoing in the water, and hung around for our entire cast.
We have been switching back and forth between beautiful sunny clean living days, and dismal, rain-filled, gray ones. We’ve had our first hint of the big waves the southern part of earth has in store for us, and it was pretty big...and only going to get bigger. Now, coming up on the third week, it’s getting really cold.
Kati works, bundled against the cold, inside the large rosette prepping its sample bottle array for the next cast (deployment to the ocean floor for sampling there and on its way back up). Photo by Katy Hill
Casts were delayed for most of the day as the ship's scientists fell into a waiting lull of game playing, including Backgammon and Hearts. It was a pleasant little break that everyone needed and spirits are yet again high and motivated to go out and sample that water.
Outreach coordinator’s note: If you live in South Florida, chances are good you’ve already seen the Saharan dust Kati tells us about without realizing it. Riding the easterly winds across the Atlantic Ocean, Saharan dust falling out over South Florida frequently appears as a fine red-brown coating on cars’ windshields, much to the annoyance of their owners.
Kati has prior cruise experience, so she’s an invaluable mentor for the students new to cruising. Weeks away from land and just getting their “sea legs,” they have to shoulder a lot of responsibility while making the often-difficult adjustment to life on this most challenging of the world’s oceans. Kati’s sense of humor and ready empathy are great confidence-builders.
The trace-metals team collected enough samples to fill more than four-dozen large, heavy-duty picnic coolers, which protect them — not cool them — during shipment. They stabilized the samples with an acid before shipping them via sea out of Capetown, S. Africa, back to FSU in Tallahassee, Florida. The coolers took about two months to cross the Atlantic — a lot longer than the Saharan dust!
Hope you enjoyed this report. Soon we’ll be back with more, including introductions to additional members of the FSU cruise participant team, without whom a successful cruise would not have been possible. We’ll have a first-time-cruiser graduate student’s impressions of the sights, sounds, and the wave of excitement that engulfed all of us as we cruised into a visual cornucopia: floating ice in every direction. We’ll also bring you some preliminary results of the data gathering. Ciao for now!