LDEO in situ 14C Lab

Beginning July, 2006 Brent began assembling the in situ carbon-14 (14C) lab at Lamont-Doherty Earth Observatory. We are only the second lab in the world with capabilities to extract cosmogenically produced 14C from quartz. The lab will significantly increase the utility of in situ 14C in studies such as glacial chronologies, landscape evolution, and paleoseismology to name just a few. 


The extraction and cleanup lines were designed by Nat Lifton (U. Arizona) and Jeff Pigati (U. Arizona), both of whom have consulted with Brent during construction.


June 2008 Update: We have just moved to our new building, the beautiful Comer Geochemistry Building. The lab now has adequate space and cooling capacity to handle our thermal load during the extraction process. We are in the process of running blanks and will run samples in October following the end of the field season. We have also constructed a new graphitization line that can graphitize two samples simultaneously, greatly reducing the time between sample extraction and measurement via AMS.

Photo of the auxiliary furnace and vacuum line. We use this furnace to clean break seals and other glass pieces in an ultra high purity (UHP) O2 atmosphere. The vacuum system is also used to pump out the O2 source line.

Above is a schematic drawing of the extraction line used at LDEO. It is a single pass system with an UHP O2 carrier gas at ~50 torr. Drawing from Pigati et al., in prep.

Photo of the tube furnace. Here we fuse the quartz grains at 1100°C in LiBO2 and O2 carries the evolved carbon into a quartz bead combustion furnace, where all carbon species are converted to CO2.

Photo of the main extraction line. The quartz bead furnace is not visible and the main furnace is left of the picture edge. The coil trap where CO2 is collected can be seen in the foreground.

Photo of the gas cleanup line. Currently, the line is approximately 1 day away from being completed. The CO2 is transferred from the extraction line to the clean up via a break seal. Using the cleanup line, we remove H2O, SOx, NOx, and halides. We also measure the amount of carbon extracted from the quartz and dilute the sample to 700 to 800 μg of carbon to make the 14C measurement easier.

This is the graphitization line that reduces the clean CO2 to graphite using hot zinc and iron. We still need to characterize the line and understand its blank. This will likely be completed in October as well, following the field season.