Our big question
How do sediments influence the morphology, or shape, of the webbed microbial mats? Ancient fossil mats are similar to these modern examples in Lake Joyce, and our observations will improve interpretations of the relationship between ancient mats and the environment where they were growing billions of years ago. In Lake Joyce, the environment has been changing with more days above freezing. This warming causes the glacial ice around the lake to melt, leading to more water and sediment flowing into the lake. How much sediment? And is the sediment settling evenly in all parts of the lake? And how much is it affecting mat growth and shape?
Problem No. 1
There are numerous challenges that had to be overcome in order to measure the amount of sediment accumulating in the lake. First, we need to identify where the webbed mats are, because that’s what we want to focus our research on. We’ve solved this problem by drilling countless holes in the lake and using cameras and other instruments to “see” what’s down there.
Problem No. 2
Another problem of measuring sediment deposition is that a collection device would have to be in place for a year in order to see a change over time. If we place it this year, the hole we use will freeze over and we’ll have to drill down to get it next year. The lake ice has a lot of sediment in it, which is released and falls to the bottom of the lake every time we drill a hole. So how do we extract the device next year without pouring lake ice sediment on top of it, clouding our results?
The Solution
Tyler has solved these problems and devised a creative plan to collect and measure the amount of sediment being deposited, which he’s explained in his blog:
1) Drill a hole through the ice cover and let any released sediment clear out 2) Insert a 6”-diameter PVC pipe to case this hole in the ice cover 3) Lower in the sediment traps 4) Insert a smaller diameter PVC pipe with an electric heating element wrapped around the lower 10 feet 5) Cap this whole assembly and pressurize it to displace the water above the heating element 6) Let it freeze up…
A drawing which explains how the sediment traps will be dropped into Lake Joyce.
Then, when the research team returns to Lake Joyce next year, Tyler can plug in the heater and free the internal pipe from the set-up, extract the sediment collector through the larger pipe, and then remove that outer pipe too.
These raw pipes will form the sediment traps that we'll use to measure the amount of sediment collecting in the lake and how it influences mat growth.
In devising this plan, Tyler got a lot of help from PVC piping experts. He also had to figure out how to fit all 700 pounds of pipes in a giant crate for shipping! These pipes were supposed to be placed during last year’s field season, but the government shut down and the crate of pipes has been waiting for Tyler at McMurdo station for the past year. Fortunately, that means that I get to be a part of his project!
These crates are waiting at McMurdo Station for us to pick up. They contain all of the pipes needed to form sediment traps for our study.
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