Thursday, March 27, 2008

Snow Day

Today we took a snowmachine ride to the Barrow Environmental Observatory (BEO) to sample snow. The BEO is an area of land over 7,400 acres in size permanently set aside for Arctic research experiments. The land belongs to the UIC (Ukpeagvik Inupiat Corporation) and they have set aside this land specifically for scientific research. The existence of the BEO is a testament to the commitment of the North Slope residents to the advancement of science and to collaboration between local people and scientists. BASC has been designated to manage the operations at the BEO and the National Science Foundation also has a cooperative agreement with BASC to support management of the BEO. The North Slope Borough (northern Alaska's regional government) also supports the BEO. In short, it is a great place to conduct research, as there is an existing infrastructure that makes the life of a scientist much easier than just tromping off into the tundra un-aided (or un-invited).

You can see from the photos, we try to take precautions not to accidently contaminate our samples. We wear Tyvek full-body suits that slip over our clothes/coats/parkas. We wear nitrile gloves. We also walk a ways upwind of our snowmachines. Our sampling scoops/shovels have been washed throughly and are transported to the site wrapped in foil and then plastic. We look rather funny out there on the tundra with our "bunny suits", but it's all for a good cause.

And now for the science!:

The snow we sampled will be used for several purposes. First, we will be extracting organic polltuants from the samples. We will melt the snow and pass it through a glass column that contains small particles of an organic resin called XAD. The pollutants should "stick" to the resin and the water will pass through. We'll then package up the XAD resin and ship it back to Villanova where we'll extract it and analyze what comes off to identify and quantify what was in the snow. We're looking for things like pesticides, PCBs, etc. The reason we don't do the extraction here is because it takes a rather large volume of solvent, and we don't want to generate a lot of chemical waste while we are here in Barrow.

We'll also take a small volume of melted snow (about 300 milliliters) and do a different kind of extraction - this one is using "stir bar sorptive extraction". Basically, we have a small magnetic stir bar that is coated with an organic polymer called polydimethyl siloxane (PDMS). The sample sits on a magnetic stirring plate and the stir bar agitates the sample for several days. Again, the assumption is that the pollutants will stick to the PDMS on the stir bar. We'll then extract the stir bar using a very small volume of hexane and Ian will be able to analyze that on the GC that we have on-site here. We can do this analysis on site because it generates virtually no chemical waste.

Finally, Glenn and I will be using some of the snow to make solutions that contain known amounts of pollutants. (Very small quantities - the concentrations are a few micrograms of pollutant per liter of water). We're going to seal these solutions in glass containers (small little vials called "ampules") and set them outside in the snow and let them "cook" in the sunlight. We think that some of the pollutants are going to degrade when left to "cook". Over the course of many hours we will monitor the concentration of the pollutant (since we know what we put in at the start, we can see how much of it degrades, or goes away). If it goes away fast, then it means that photochemistry (that is, chemistry driven by sunlight) is a potentially important way the pollutant degrades in this environment. If it goes away slowly (or not at all) then it means that photochemistry isn't so important.

We want to know about all of this, because ultimately these pollutants will end up getting into surrounding soils, streams, lakes and the ocean when the snow melts. The local indigenous population relies heavily on wildlife from the area as a food source and unfortunately, these pollutants are showing up in the fish and whales and seals and other wildlife they consume. We want to better understand HOW the pollutants are getting to their ultimate destinations and how the pollutants might change while they are sitting in snow and ice, waiting for snowmelt to transport them elsewhere.

So that is a description of our goals for this particular set of samples. We'll be going out a lot more to sample ... and you'll see those trips on here as well.

No comments: