Just under 70 pounds

by srosengard

Image (Above: Before landing in Goiania, capital of the state of Goias in central Brazil).


Packing light is not the central philosophy of preparing for field work, and the baggage I am tied to for the next 10 days in central Brazil affirms this. One 68 pound suitcase, and a duffel bag that can fit an average-sized adult. Fortunately, the approximate weight limit of what I can carry on my own equally matches the weight limits for check-in.

In the past 24 hours, I have grown ever the more aware of the trust we put into the check-in agents at airport gates. Perhaps I should not take for granted that all the equipment essential to make a worthwhile field expedition in the Amazon River Basin can actually survive three flights from Boston to Brasilia to Goiania, a sprawling city that sits just beyond the intersection between dry cerrado forest and humid rain forest, at the center of the Brazilian Amazon.

My goal for the next few days is to collect hundred liters of river water from streams flowing through a giant ranch 12 hours away from Goiania by bus (stay tuned to see if my luggage survives that too!). And so it follows that most of my baggage contents are empty plastic containers, from bottles of various size to huge collapsible cubitainers, which can expand to hold almost 20 L of river water (or 5 gallons) at a time.

Although I might have over-packed my water sampling supplies, I do not actually plan to carry hundreds of liters of water back to the United States. If all goes well, I will leave with just the suspended particles of organic carbon and minerals, the soils and plant remains that have washed into the water from adjacent lands. When I analyze these solid materials back in lab, its chemistry will (hopefully) tell us something about which plant types produced this river-borne material in the first place, as well as the history of this organic material since being introduced to the soil and riverine environments. Because this organic material originally came from carbon dioxide in the atmosphere, many scientists are interested in keeping track of its movement from plant to river.

And hence the 68 pound suitcase is full of filtration units to separate the solids from this water. These units have been developed and refined through years of field work by scientists from my rivers research group from Woods Hole Oceanographic Institution and Research Center. A vertical cylinder, the filtration units accept water from the top and pushes it through a filter at the bottom that, very much like a coffee filter, collects only solid materials (or the coffee grinds) too large to pass through its small pores.

Image (above: A filtration unit when connected to a bike pump, during a practice run in Woods Hole with the more experienced river scientist Britta Voss)

With gravity alone, it would take much longer than my daylight hours to get all the water through the filter. So us river scientists are also typically equipped bike pumps, which I will use to pressurize the air inside the cylindrical filtration units, pushing the water downward past the filters faster than gravity would manage alone. Imagine being able to have your drip coffee ready in a few seconds rather than a few minutes. I hope that this bike pump accelerates my work over the next week by a comparable order of magnitude, as well.