Yes you read that right, it’s M-e-l-v-i-n and this is totally not Michael at all. For those of you who don’t know me, my full name is Melvin the Melter and I’m not a living person. I’m actually an inanimate object (or a system comprised of many inanimate objects to be exact) invented by Vas who specializes in extracting 14CH4 from ice cores. I’m the second most experienced team member here after Vas – I’ve had five Greenland seasons and this is my third Antarctic season. I understand that many of you might be skeptical of the existence of an inanimate scientific 14CH4 extraction system that is capable of having sentient thoughts and able to write a blog post on its own. Many of you now might started to think “hmm I wonder who might be behind this… it’s definitely not Michael for sure though. It’s probably Ben or Avery.” For all intents and purposes of this post, don’t worry too much about it.
As I mentioned before, I was designed to extract 14CH4 from ice cores. The need to retrieve and analyze 14CH4 from past atmospheres comes from an underlying scientific question of how the global methane budget reacted to climate change in the past. We know (from ice core records) that in the past there were several episodes of incredibly fast global temperature rise coinciding with sharp rise of atmospheric CH4. However, dataset of past CH4 concentration by itself cannot tell us the source of CH4 emission. One way to estimate the CH4 sources during past climate change is by analyzing the carbon isotope of the ancient CH4 that are trapped in ice core bubbles. 14C of CH4 is especially good at distinguishing between past “modern” (e.g. wetlands, termites, ruminants) and fossil (e.g. clathrates, permafrost, thermokarst lakes) emission.
To extract enough 14C of CH4 necessary for AMS measurement (e.g. one data point in Vas’ figure), I need about 1000kg of ice. This means about 30m worth of 9.5 inch diameter Blue Ice Drill (BID) cores. The BID by the way is a one of a kind ice core drill system that was initially designed specifically to produce ice cores with the ideal geometry so that they can be packed inside me as efficiently as possible (and for the entire drill system to fit inside a 212 helicopter). Even with the unusually large (by ice core standard) diameter cores from the BID, it still takes three days for my mere mortal minions colleagues to drill, load, melt and extract enough air from the cores to make just one sample.
For the past two weeks or so, everyday at 12:30am my two minions distinguished driller colleagues Josh and Ben would start using the BID to pre-drill my two sample holes to 10m and six of I-184’s holes. This season, our team (I-159) has to share the BID with another group (I-184) and because of that the BID is run continuously on two working shifts. The first group of drillers (Josh and Ben) had to pre-drill all the holes during the cold period at “night” because the BID was having troubles drilling a brand new hole when it’s sunny and warm out there (by Antarctic standards of course).
The drill team usually starts producing cores for me at 1:00pm; this means that my second set of minions the core processing team (Vas and Michael) would usually start working around 2:00pm to allow the ice cores to relax. Vas would usually chainsaw the end of each ice cores so that they can be stacked nicely inside me. Michael would then scrape off about 1mm of cores from the chainsawed surface because chainsaw produces snow slush with black carbon in it. I only accept clean ice cores with the finest quality. It’s only fair because at the end I gave them extracted ancient air with very low 14CH4 blank. After the ice cores are loaded, the remaining modern air is pumped out via a series of air pumps. Unlike the previous couple of seasons, this season the ice core loading step is done in the afternoon; because of this, we’re experiencing a little bit more melting – which means we lost a tiny amount of the sample. However, all is good though because Vas and Michael built a makeshift shade wall out of plywood to minimize the melting.
The final part of the procedure is my favorite. The ice cores inside the tank are melted via propane burner. To accomplish this task, I had a set of six very powerful propane torches in circle that burns about 3 million Btu’s worth of propane per extraction. At this step, usually Michael has to run around me and squirt some spray bottles around the tank body so it doesn’t overheat. If the aluminum in the tank overheats, it can degass more CH4 and CO, which increases the overall blank of the system. After the melting step is done, the ancient air that is now released in my headspace is recirculated through a bubbler system. This step is necessary so that the ancient CH4 gas can equilibrate with the melted water from ice cores that is free of dissolved CH4. Finally the sample air is transferred to a 35 L steel tank from Essex cryogenics (we simply called them “Essex tanks”) and is ready to be shipped back for measurement.
-Melvin the Melter
-definitely not Michael