If you’ve read the title of this post, you already have some idea of what it takes to develop and assemble a novel scientific instrument. For the past week or so, my colleague and I have been taking ordinary parts you may find in a lab—tubes, pumps, bottles, a glass cell—and assembling them carefully to achieve a greater purpose. In this case: precise automatic measurements of seawater chemistry.
As you may imagine, perfect results don’t come immediately when building an instrument from scratch (oh how I wish they did!). But during my first long-term research cruise, I’m quickly realizing the benefits of persistence and ingenuity. That’s where the concept of “tinker, watch, repeat” comes in. First though, I’ll explain the purpose of this particular instrument. And to avoid losing you, I’ll try to do so as briefly and simply as possible.
There’s always been some amount of carbon dioxide in Earth’s atmosphere, but we humans are disrupting natural levels with practices like fossil fuel burning (you’ll know all about that if you’ve read this post). Much of that extra carbon dioxide dissolves into the ocean where it increases seawater acidity and alters the balance between certain dissolved carbon molecules (called carbonate, bicarbonate, and carbonic acid). As the NOAA Ship Ronald H. Brown traverses the eastern Pacific, our intrepid instrument will measure three quantities continuously in the surface water: pH (the acidity of the water), carbonate ion concentration (the molecule that critters like oysters and clams use to make their shells), and total alkalinity (a parameter influenced by all three of those dissolved carbon molecules). The results will give us a better idea of how human carbon emissions are influencing marine life and how effective the ocean is at sucking up our “extra” carbon dioxide.
Okay back to the tinkering story. So once our instrument is initially assembled, we attempt to run it. Unsurprisingly, bugs appear. A faulty pump. A clogged valve. These issues are addressed and resolved through creative solutions…the tinkering. Now the instrument is operating and collecting data. We patiently observe and assess the data…the watching. The results seem variable and sometimes questionable. We modify a pump’s speed, adjust the measurement timing, ensure the temperature is accurate. Then we run the instrument some more, evaluate the data, tinker more…you guessed it, the repeating.
Eventually, we begin to see results that are stable, consistent, and plausible. It is at this time that we measure standard seawater, samples whose chemical characteristics have been precisely measured and preserved using tried-and-true methods. We check for consistency between our measurements and the known values of the standards, calibrating ours to remedy slight discrepancies. And finally, the instrument is functional, tuned, and ready to collect meaningful data. Yahoo!
This process has been my story over the past week or so. Now the instrument that we so meticulously assembled and calibrated is gathering seawater carbon chemistry data constantly as we cruise up the West Coast. And in reality the tinkering, watching, and repeating never ends; we continue to measure standards periodically to ensure all systems are operating properly.
Though the process can seem tedious at times, it’s important to remember that these measurements go a long way in improving our overall understanding of the ocean-atmosphere system. For example, surface pH data can provide information on the motion of marine currents, the activity of organisms in the upper ocean, and the exchange of gases between the ocean and atmosphere. Carbonate concentrations have critical impacts on marine creatures and are useful for predicting imminent effects on West Coast shellfish fisheries.
Solving one problem only to be presented with another is as exhilarating as it is exhausting. As a scientist, especially during instrument development, “tinker, watch, repeat” is just a way of life.
Author: Jonathan Sharp