July 16, 2006 - What ARE we doing here?!, Description of the project Options

[Maggie_Kane]

Today we learned about the Limnology of Lake Linne (Linnevatnet) where we will be working. Limnology is the study of inland waters (both salt and fresh water). Limnology is important here because lots of the material moved by the Linnebreen ends up in the lake. We are able to look at what has accumulated in the lake over time and get a glimpse of the history of the glacier and river.

We are lucky because the lake sediments in Linnevatnet are striped with what we think are seasonal bands (called varves). This helps us read the years like we might read the rings on a tree stump. The top stripes are the most recent, and the deeper you go, the older the layers. We see these in cores we will take from the lake bottom. We will have to be careful to locate where each core comes from, and make sure not to loose ANY of the sample – one inch represents about 10 years or more! We will also have to be careful not to fall out of the boat!

Why are we are studying the sediments in the lake? It can tell us a whole lot about past environmental conditions. Imagine that the glacier experienced a really cold time – would you expect as much sediment to come down the river and into the lake then as in a warm time? Probably not! When it is warm, the glacier will melt faster, and as the water runs, it picks up and carries a lot more sediment to the lake. Some of the other components of our lake study will include collecting data on temperature, salinity (saltiness) and using filter traps suspended in the water. This is just one piece of a much larger study about what has happened to our climate over the past several thousand years.

Our project will consist of several main parts besides our lake study:

* We will be working with our weather station positioned at the far end of the lake to collect data on wind speed and direction, rain accumulation, radiation values both up into the sky and at the ground, barometric pressure and humidity and the temperature of the soil below. The weather station is positioned on a tall pole and collects data all year long with computers logging data every 30 minutes! We will collect the data from this past winter and be able to download it into our computers and then look at 11 months worth of data. Fun!

* Work on the glacier will involve mapping the edge with a GPS to add 2006 to our map of how far back the edge is retreating. This sounds easy, but the ice sometime looks just like debris, and sometime what looks like debris is actually filled with ice! The glacier has been retreating faster and faster in recent years: back in the 50s, it retreated an average of just over 6m per year. Since 1995, it has receded at an average rate of 35m per year. That is a huge difference! We also can learn about overall melt by looking at ablation stakes posted all along the length of the glacier. These poles have marks on the side that we can look at and measure the height of the ice. Probably the hardest part of that study is the 20 kilometer round trip hike every day or so. Wow!

* We will be working in the river that connects the glacier to the lake as well. We have a really cool piece of equipment that pulls samples from the river up a tube and squirts it into a marked bottle. This happens every 2 hours all day long. Each day, we will go up and collect the samples. What can we learn from those? If we filter out the samples in papers like fancy coffee filters, we can dry and then weigh the sediment and find out how much the river is carrying at any hour on any day. Just pretend that there was a heavy rain at 10am one day. It made the stream all muddy and fast running. Our sample from 11 might show us how much sediment actually got moved during that event. That helps us understand what might be on its way to the lake. If we can correlate (match up) our weather data and sediment data, we have a better understanding of how things work in the entire system.

Lots and lots of brilliant geologist have worked on projects similar to this all over the arctic. Often, when scientists collect data, they are trying to add new and helpful information to a story that is already partly understood. The data collected by these bright and enthusiastic students and amazing researchers will be tremendously important to the larger study of how our world climate is changing.

We will travel today to Isfjord Radio on a big boat called the Stockholm. It will take several days to get set up at our field station, so stay tuned for great stories and pictures of our adventures in science!