This is Dom and Gaby writing. We know it has been a while since we last wrote - It has been a bit of a hectic semester, but we have interesting results to share with all of you!
With all of our samples thoroughly analyzed by Harbin, we were finally able to start seeing some results for our data. Two weeks ago we used the GIS data compiled by Sarah to calculate upstream area for the basin 49 watersheds.
As you can see in the map below, our watershed is divided into 3 branches, the west branch (in blue), the east branch (in red), and the main stem in the middle (in green). The watershed where the three branches converge is shaded in yellow.
Last week we began plotting unsupported Pb-210 activity against upstream area, and what we discovered is really spectacular. First, we saw that the main stem had a lot less un-Pb than the tributaries, and that in both cases the amount of un-Pb generally increases with upstream area.
Then, after we separated the results by branches, it turns out that the central river stretch in basin 49 is almost completely stripped of unsupported Pb-210. The graph below shows that most of the Pb-210 that is showing up in main stem river samples is actually from the eastern and western tributaries.
This data along with the fact that there is no Cs-137 in this basin indicates that there has been intense surface erosion. The results of this graph show that the central river stretch is more eroded than the tributaries. Our prediction is that this is due to heavier land use along the central branch of the river. In the future, we would like to analyze Google earth images and Landsat data to confirm our predictions.
This summer Dom will be continuing his work on this project through a Mellon Mays research fellowship. Specifically he will be studying the difference between over bank deposits and in-river, suspended sediment. Gaby has been selected to participate in a Keck project that studies coral reefs in Belize. This research will be the basis of Gaby's geology honor's project.
It has been great getting to work in this project with our peers and prof. Amanda. We look forward to seeing this project continue to yield interesting data.