What is Fukushima?
In case you’ve been living under a rock or on top of an ice sheet, Fukushima radiation, refers to the release of nuclear radiation from the Fukushima I Nuclear Power Plant in Japan starting on March 11, 2011.
The release of radiation was caused by one of the world’s largest ever recorded earthquakes, a 9.0 magnitude, that struck off the east coast of Japan. The earthquake created a large tsunami up to 133 ft in parts of Japan. The combination of the huge amount of shaking and the inundation and power of the tsunami wave lead to the eventual meltdown of 3 of 6 reactors at Fukushima I and the release of large amounts of radiation from the power plant (See Wikipedia and the NY Times).
So what does Fukushima have to do with Summit, Greenland?
Ice core scientists use atmospheric events such as major volcanic eruptions to confirm the age of ice cores at specific depths. Beta radiation from upper atmosphere nuclear weapon testing during the 1950s and 1960s appear in Greenland ice cores (one such core was drilled right here at Summit, GISP2). Will radiation from the Fukushima disaster be deposited in the snowfall of central Greenland?
Dartmouth’s own Erich Osterberg, Research Assistant Professor in Dartmouth College’s Earth Sciences Department, was recently awarded a NSF Rapid Research and Response (RAPID) grant to study the impacts of the Fukushima Nuclear power plant disaster. IGERT student here at Summit Camp are assisting with the collection of snow, which will eventually be tested for the presence of cesium, Cs137.
What evidence is there that radiation from Japan got all the way to Summit?
After the Fukushima disaster began, air masses (possibly containing radiation) from multiple different elevations (red=low, blue=medium, green=high) moved eastward over Greenland, between 2 and 3 weeks after the disaster started according to two different sets of meterological data available from NOAA’s Air Resources Laboratory and their HYSPLIT model.
Now that we know what Fukushima is, what is has to do with the Greenland Ice sheet, and how it got here, lets talk about how we collected samples to test if radiation from Fukushima actually accumulated in detectable amounts in the snow pack.
Willy Wonka and the Chocolate Factory version 2.0 – White Umpa Lumpas on Ice
First we shipped three huge ice core boxes full of 45 4L Nalgene bottles from Hanover, NH all the way to Summit with the 109th Air National Guard unit. Additionally, Thomas Overly, one of the IGERTs who recently completed the 1500km traverse from Thule, Greenland to Summit and back again in May and June had left smaller sampling bottles for us to use for the first sampling procedure. The next step was to dig a huge snow pit (7m long x 2m deep x 1.5 m wide – shown below), which contained two of the sampling locations, and one other pit ~100m away (2m long x 2m deep x 1.5m wide), containing the third replicate.
Thomas, Ben, and Ian digging the big pit
Once the pit was dug, we had the immense pleasure of donning white clean suits and gloves (so as not to contaminate the samples – see Sam and I below) – and transforming into snow umpa lumpas. And FYI wearing straight white was freezing – super high albedo.
Two sampling procedures were conducted at each site. The first set of samples was for isotopes and anions; 125mL of snow was sampled once from each 5cm layer from the surface to 1m depth (see Sam and I in action below). Next we used the 4L nalgenes to sample each 10cm layer three times from the surface to 50cm. In addition to sampling once with the 4Ls, we brought the bottles inside, put them into the sink (we were on dish duty so it was no big deal), and melted the snow in bottles. We then consolidated the water from the different 10cm increments and different sampling locations into one of the three bottles. Once we had two empty containers for each 10cm increment we went back out to the pits and resampled the layers, so as to increase our total amount of water collected. The huge amounts of water from each layer and pit was needed so as to detect the very low levels of radiation, which may or may not be present in the snow at Summit.
You may ask why we only sampled the top 50cm with the 4L bottles – well the answer is that the annual precipitation at Summit is approximately 60cm, therefore sampling the top 50cm is more than enough to capture the precipitation that may contain the radioactive fallout from Fukushima.
Marcus Welker and Sam Fey digging sampling for Fukushima fallout
Overall the sampling for Fukushima was a huge success. In addition to our sampling for radioactive fallout, we observed the stratigraphy of the first ~2m, took a firn sample, and conducted permeability and density tests. Stay tuned for the results of this work.
Read Full Post »