Oregon State University

College of Earth, Ocean, and Atmospheric Sciences

Estuary Dynamics

Colleen Wall

August 30, 2012

Colleen Wall is a second-year Master's student, working with Burke Hales on ocean acidification and carbon cycling in estuaries and the nearshore.

As an undergraduate at a small college, Wall majored in chemistry and worked for two years in an organic chemistry lab. After graduation, she commissioned in the Navy for a six-year program in nuclear power. Her last two-and-a-half years were spent on a nuclear-powered aircraft carrier, operating and maintaining the primary systems of the power plant

Wall discovered that she took to engineering, "I wasn't an engineer in undergrad. But nuclear power school and all of the work on valves and pumps that I did got me interested. I felt I was actually more of an engineer than a chemist."

When Wall was getting out of the Navy, she looked at graduate programs. On a visit to the OSU campus, she met with a number of professors, one of whom was Burke Hales. "He was explaining his towed vehicle with the pump and all the flow-through systems. I liked the fact that not only was he a chemist but he was also an engineer."

Wall arrived at OSU six months before starting classes, and Hales and his main technician, Dale Hubbard, started her training. She learned how to build an underwater cable, to use different communication protocols to talk to a valve, to set up basic instruments for deployments, and do some basic electrical troubleshooting.

Hales' current research is carbon cycling and ocean acidification. Wall is researching the estuary dynamics of pCO2. Other researchers have looked at estuaries to classify them by their net input or output of carbon dioxide, however those researchers have used ocean instrumentation from boats—an expensive approach that does not yield reliable, high-resolution data.

Wall describes estuary processes as being highly undocumented. "There is a lot of sediment and other inputs from the river. Tidal influences differ depending where you are. In Netarts Bay, the water exchanges completely, every tidal cycle. In Yaquina, the tide makes it in only about halfway and then goes back out."

The basis of Wall's project is to build a prototype for conducting the estuary research with a new tool: an inexpensive, drifting, pCO2 analyzer. "We found some small pCO2 sensors that work by infrared—the same principle as the big LI-COR instruments that we use in the lab. The small sensors aren't as accurate or as fast, but they still work."

Wall's prototype drifter, being lowered over the side of R/V Oceanus for its first test deployment.

Inside the drifter is a data logger and sensors to track pCO2 readings, GPS position of the drifter, salinity and temperature in the water. The data logger has a cellular modem, so that a computer can call it and download its data once or twice a day

Wall notes, "By using a drifter, I can see the dynamics of the water. If I put the drifter in at the river end of the estuary, the GPS allows me to watch it move in with the tide, come back, and go out again. Eventually it will end up in the mud somewhere and I'll have to go out and pick it up. Downloading the data each day ensures that data will be preserved, even if the drifter gets hit by a boat and destroyed."

Wall's prototype is a proof of concept, and her work answers questions such as, "Will it work? What type of temperature probe should we use? What kind of range of pressure do I need? How am I going to wire all these things together? How am I going to set up the schedule for the data logger? How can I improve the buoyancy so it is more vertical in the water?"

If Wall can get the drifter to work and collect some pCO2 data, she will then work on improving the instrument: its robustness, cost of construction, length of life, length of deployment, and so on. After improvements, next steps could be building multiple instruments, accumulating data, and writing a paper about what is learned about estuary dynamics.

When asked about career goals, Wall replies, "I would like a career like the Faculty Research Associates have here, where they do a lot of building, instrumentation, taking and analyzing samples … understanding the science behind it and being able to be the person that makes things happen. That's what I'm hoping."


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