New labs take a while to set up but now that his is, Dave McGee is one happy paleoclimatologist.
David McGee, Assistant Professor of Paleoclimate, joined the EAPS faculty in January 2012. Now, almost two years on, his group has a beautiful new laboratory to carry out their research.
McGee’s research focuses on building and interpreting records of past climate changes using natural archives such as stalagmites and seafloor sediments. These valuable deposits preserve continuous records of past conditions in the atmosphere and ocean, enabling unique insights into the patterns and drivers of past climate changes.
Much of McGee’s work involves reconstructing inputs of windblown dust to the ocean over the glacial-interglacial cycles and millennial-scale climate changes of the last 200,000 years; this work documents past changes in the hydrological cycle and provides estimates of the delivery of essential micronutrients to the surface ocean.
Recent work has used a series of sediment cores from North Africa’s western coast to reconstruct changes in dust emissions from the Sahara Desert from the peak of the last ice age to the more recent past. This work demonstrated that cores forming an 800-km north-south transect along the margin record similar changes, providing greater confidence than has been available from previous studies employing only one site. Most significantly, this work provides quantitative estimates of past dust emission changes – ranging over a factor 10 from peak emissions during two millennial-scale cold events at the end of the last ice age to minimum emissions during the “Green Sahara” climate between 5000-11000 years ago – allowing exploration of the climatic and biogeochemical impacts of these changes in dust transport and deposition in the North Atlantic Ocean.
McGee’s group is also involved in an Integrated Ocean Drilling Program to the Japan Sea targeting sediments that record the evolution of the East Asian Monsoon over the last five million years. The group will use changes in the delivery of windblown dust and riverine sediments to the region to reconstruct changes in monsoon precipitation and winter/spring westerly winds.
On land, McGee’s group uses calcium carbonate deposits formed in lakes and caves (e.g., stalagmites) to develop records of past precipitation changes. A major focus of his group’s current work is in understanding past wet episodes in two currently dry places – the U.S. Great Basin and the Atacama Desert of northern Chile.
These studies involve a variety of types of data, but at the center of all of them are uranium-series isotopes, which he uses for precise dating in terrestrial deposits and determination of accumulation rates in marine sediments. He is currently primary advisor for three graduate students Christine Chen, Christopher Kinsley, and Elena Steponaitis. Graduate students Alex Andrews, Andrea Dubin, Ross Williams and Ning Zhao are also affliliated with the McGee Lab, though McGee is not their primary advisor. Postdoc Chris Hayes, UROP student Jessica Fujimori and Lab Technician Irit Tal complete the team.
EAPS News recently visited the new facility to take some pictures and hear about the project.
Q: This is the first lab you have had full responsibility for setting up - what did you find the biggest challenge?
McGee: The timeline was a big challenge - when I was first starting many people told me that their renovations took 2 years from start to finish, and I couldn’t see why it would take that long. In the end, though, even with everyone on the planning and construction teams working very hard, it still took just a few months shy of 2 years (I know because my daughter was born a week after we starting planning in earnest, and she's closing in on 2!) It was hard to stay patient with the process given how excited we all were to have our own space. I'm very thankful to the folks who let my group use their facilities in the meantime - Sam Bowring, Roger Summons and in particular Ed Boyle.
Another challenge was educating myself sufficiently to make informed decisions about all the important minutiae that go into making the lab work for us - from duct linings to hood designs to eyewash placement. I can't tell you how many flooring and paint samples we tested to arrive at materials that would meet our needs for acid resistance.
Q: If you had to choose one bit of the lab you particularly love which would it be and why?
McGee: I love the clean lab. It's streamlined, efficient and, well, clean. A big part of how it feels is all the windows - it's remarkable to have a clean lab with natural light in it as well as clean sight lines to the lab space outside it.
Q: What special features does your new lab have to enable you to do the specific work you do?
McGee: Four things... First, laminar flow hoods: unlike standard hoods, in which air flows from the outside lab into the hood over your samples, these have built-in ULPA filters (think HEPA but at a higher standard) that pass ultra-clean air directly onto and past your samples, all within the hood; outside lab air doesn't make it in. The particle counts we've done find that air in these hoods is 100x cleaner than lab air just outside them. As a result, we're already getting total procedural blank values at the same levels as some of the leading U-series labs, and we can definitely get them lower. Next, metal-free hotplates made of graphite - to limit metal contamination of our samples as well as corrosion from acid vapors. The anti-static system in the clean lab is also key - to minimize buildup of static in a lab made almost entirely of plastic (static is a huge nuisance when weighing samples, dealing with small sample drops, and pipetting; it also causes plastic sample vials to attract airborne dust --- so this is not just about avoiding getting shocked, or having good hair days in the lab). Finally a hood that sprays water through its exhaust vapors, capturing almost all of the acid fumes and draining the water to the building's neutralization system rather than sending the fumes out onto the roof.
For a virtual tour, visit the EAPS flickr channel more
Looking forward to lots more dusty discoveries in the years to come.