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  • Oliver

More firsts - Theory and practice in sampling pollutant samples in mountains

Updated: Dec 14, 2019

Some of you might still remember Helens post where she described all her firsts when she was visiting Leipzig and conducted some work at the UFZ. Here are my impressions and thoughts of my first P³ sampling period in the Pyrenees.

After I started my PhD roughly 9 month ago I had a lot of time to build up some basic knowledge about the theoretical behavior of contaminants in mountain lakes and familiarize myself with some preliminary results on the pollution of our P³ lakes (kindly provided by Mara Grodtke). By doing this I thought I got a good overview. However, when actually standing in the field it is not that easy to bring together theory and practice. For example, all authors highlight the fact that mountain lakes are located at very remote sites and receive their pollutants via atmospheric transport. Therefore, one cannot just stand at a lake and see the sources of pollution (like a smoking chimney). Nevertheless, when I was standing beside my first mountain lake and looked down from the plateau into the valley, which was just covered with grass and did not show any sign of pollution source, I caught myself thinking about the fact whether pollution can actually be a problem at this site. This was of course foolish. Many papers have already proven the fact that certain chemicals can reach lakes at high altitudes, especially also chemicals used in agriculture. So, i realized how well hidden some environmental problems actually are. Hence, projects like P³, which raise public awareness for problems that would otherwise be overseen, are of major importance.

The theoretical transport of pollutants vs what you actually experience in the mountains

Another topic is the sampling itself. While sitting in front of your comfortable desk it is easy to plan a sampling campaign. However, when you are actually in the field things get more difficult, much more difficult. An excellent example for this is the sampling of the sediments of our lakes. Sediments act as perfect sink for pollutants that enter lakes and are hence of immense value for the characterization of how severely polluted a lake is. Therefore, one of my top priorities for this sampling campaign was to obtain excellent sediment samples for all of the P³ lakes. However, little did I know about how difficult it is to wrest the samples out of the lakes. The plan was to simply sample sediment from the edge of the lake. Unfortunately this is not possible, as most of the lakes at high altitudes have only very rocky and organic poor sediments at their corners, while the desired more finely and organic-rich sediment is in the middle of the lake. They are simply oligotrophic lakes with little nutrients and hence sediments.

Picture: Image of typical lake sediments for a small lake at high altitudes.

Further, at first glance going into the water and diving for some sediment sounds like a good idea. Especially in spring, water temperatures at 10°C are considered warm, and with water even colder diving for sediments becomes pure torture. After experimenting a bit, two approaches have proven to be the best. In approach 1, one has to search for shallow areas that allow you to walk into the lake as far as possible and then obtain the precious sediment samples. Approach 2, is to jump from rock to rock till you can try, while balancing on the rock, to fish for some sediment. Both approaches often result in more contact with the cold water than hoped for. But if there is some analyzable sediment in the sampling container at the end of the day it was worth the effort and will hopefully help to develop a deeper understanding of the dynamics of pollutants in high mountain lakes

While performing mountain research is definitely one of the physically more demanding research topics it also doesn’t fail to make up for the stresses and strains. So it grants you panoramic views you can hardly find anywhere else and even when you think “Now this was a great view today, how much better can it get” then nature will for sure be able to surprise you and astonish you again in the next valley. And if that’s not enough to make you forget your tired legs then nature will for sure think of something else to comfort you. This can be a marmot which takes its afternoon nap in the middle of your hiking path and decides, after a moment of shock and confusion when it sees you approaching, to complain loudly or escape in a rapid downhill sprint .

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