I recently prepared a blog for Der Standard an Austrian newspaper entitled: Wie unberührt ist Grönlands Schnee? I say prepared as really it was re-written by my colleague Elisabeth Schlosser to make the German sound more native!
Anyway here is an English version of it:
Nowadays my work is primarily studying glaciers, but I used to work in a water chemistry laboratory, studying ice cores from the Canadian Arctic.
An ice core section showing dust layering inside it. Photo B. Markle
I always liked how clearly you can see the impacts of some human activities in ice cores, for example by looking at the lead records you can see the rise of leaded petrol use in the 1920s, and then the subsequent advent of unleaded petrol from the mid-1970s to the early 2000s.
Measured lead (Pb) levels in an ice core from Greenland (annual samples) and the Monte Rosa massif (5-year samples) in the Alps. Lead can come from a variety of sources but you can see the pattern of leaded and unleaded petrol usage. Graphic redrawn from Osterberg et al, 2008; Greenland data from McConnell et al (2006) and Alpine data from Schwikowski et al (2004).
Although the levels of lead measured in the ice core from the European Alps are much higher, the pattern of leaded petrol use can also be seen in the Arctic areas even though most of the industrial activities and cars are far away from the Arctic. This is because the snow falling in the Arctic is made of moisture that has travelled far through the atmosphere and so it carries the emissions and pollutants from elsewhere into the Arctic. Thus, some of the impacts of our activities in mainland Europe are felt in the farthest reaches of our planet.
A family of pollutants that is of particular interest in the Arctic are the so-called persistent organic pollutants (POPs). POPs are man-made compounds like pesticides, herbicides and fire retardants that are not easily broken down in nature. Because of being so long-lived, they can be transported far from their place of emission or use into the Arctic, where they are stored in snow, water and soil. Unfortunately these POPs are generally toxic, and have been found in elevated concentrations in the fatty tissue of Arctic fish, seabirds, whales, polar bear and human populations. POPs may be responsible for long-term health issues, in both animal and human populations, including hormone disruption, infertility and cancer.
Last year I was asked to participate in an expedition called POP Greenland to collect samples of snow from Greenland to see how much POPs are being transported into the Greenlandic snow. We will use non-contaminating sampling techniques to collect large samples of fresh snow, which will later be analysed to find out the concentration of pollutants within it.
We were hoping to traverse the icesheet taking regular samples but the logistics for that did not work out, so now we are sampling at two locations in east Greenland and we have linked up with colleagues from the Greenlandic Geological Survey, the Norwegian Polar Institute and students from the Royal Scottish Geographical Society Polar Academy, who will take samples from other locations on Greenland to spread the reach of our study.
Once we have found out the current levels of modern POPs in the snow, we will use 3D representations of air flow from atmospheric models to trace their transport pathways back to the likely location of the source emission. By doing all this, we can develop a much better idea of the present deposition and storage of POPs in the snow and ice of the Greenland icesheet.
Knowing the modern day levels and transport pathways better will also enable us to make a more educated estimate of how much pollution was deposited in the Greenland snows since the start of the 20th century. This is important because, during the middle of the last century, much higher levels of more toxic, pesticides and other POPs were used. The Stockholm Convention which has been in effect since 2004 restricted use of 12 of the substances deemed most potentially damaging. However, meltwater runoff from the icesheet is coming from both modern and older snow and ice, and this will flow into the rivers and surrounding ocean. Our work will help us find out if, counterintuitively, meltwater from the seemingly ‘pristine’ Greenland icesheet may in fact present a source of toxic pollution to the Arctic environment in the coming years.
In case you are wondering, the sampling team is being kept as small as possible, and we will do our sampling by ski to minimise the use of vehicles in Greenland. To get there, from Austria and Poland, we do however have to use planes and helicopters. As far as possible the carbon emissions of this travel have been offset, but we know it is not perfect.
Our project is supported primarily by a National Geographic Society Explorers Grant. You can follow our project on the web (www.popgreenland.wordpress.com/) and via social media (@POP_Greenland or www.facebook.com/popgreenland/). Agna and Justyna set off for Greenland on April 10th – I will join them on May 15th.
If you are really interested in this topic the Arctic AMAP report is a great source of information: https://www.amap.no/
- Osterberg, E. C., Mayewski, P., Kreutz, K., Fisher, D., Handley, M., Sneed, S., Zdanowicz, C., Zheng, J., Demuth, M., Waskiewicz, M. and Bourgeois, J. (2006) Ice core record of rising lead pollution in the North Pacific atmosphere, Geophys. Res. Lett., 35(5), 2–5.
- McConnell, J. R., S. Kipfstuhl, and H. Fischer (2006), The NGT and PARCA shallow ice core arrays in Greenland: A brief overview, PAGES Newsl., 14, 13– 14.
- Schwikowski, M., et al. (2004), Post-17th-century changes of European lead emissions recorded in high-altitude alpine snow and ice, Sci. Technol., 38, 957– 964.