Particulate geochemistry update: Using synchrotron light to see black carbon nanoparticles

In the 4 months since our return from Greenland, the Black and Bloom team has been busy analysing samples, collecting data, and preparing manuscripts. In August, Steffi, Alex Holland, Liane, and I all had the opportunity to present our research at the Goldschmidt geochemistry conference in Paris. Steffi has recently finished writing a manuscript on the diversity of the microbial communities collected from the ice sheet during the 2016 field season, and is currently analysing the microbial samples collected this summer.

One of the big tasks the particulate geochemistry team have been preparing for is analysing the black carbon nanoparticles we collected in Greenland. Black carbon is the soot produced during fossil fuel combustion, and is well known for its ability to reduce albedo as a result of its light absorbing properties. One of the challenges of studying black carbon is that these particles can be as many as 3000 times smaller than the width of a human hair. In order to study these particles, we use a circular particle accelerator called a synchrotron. The synchrotron accelerates electrons to almost the speed of light, and these electrons produce light that is 10 billion times brighter than the sun. We are able to use this light to study the composition and structure of materials – in this case – our black carbon nanoparticles.

Last week Jim, Liane, and I visited Diamond Light Source, which is the only synchrotron facility in the UK. Understanding the chemistry of these particles will help us determine where they are coming from, which is important if they are influencing the albedo of the Greenland Ice Sheet. This visit to the synchrotron was a successful test of our experimental method, which we will put to work when we return to the synchrotron this coming March.

Our black carbon analyses are just part of our aim to understand the atmospheric deposition of particulates onto the Greenland Ice Sheet. Jim has been busy crunching the aethalometer and optical particle counter data collected in the field, and I have been imaging the particulates, collected on the aerosol sampling tower, using scanning and transmission electron microscopes. This data will come together in the coming months in a paper I’m currently writing on atmospheric particulate deposition.