Week 6: First Results

This week, things started to feel more like real analysis rather than just data collection. While I continued collecting data by completing another round of sampling, this time under much hotter conditions (this week was very hot), and I also received the results from my first full set of Occoquan samples.

The results were not what I expected. I expected the deep water to have the highest concentration, as I thought the PFAS might sink to the river floor. However, both the surface sample and the deep-water sample came back at around 36 ppt, which suggests that PFAS may be more evenly distributed throughout the water column than I initially thought. However, the middle-depth sample was noticeably lower at 31 ppt. While the difference might not seem huge, it is still significant enough to raise questions, especially since I expected a more consistent gradient. I will double check this by seeing if the pattern continues in my other samples.

Right now, one of my hypotheses is that this could be related to density differences or how PFAS compounds interact with water layers, but I am still researching this and trying to better understand the chemistry behind it. It could also be influenced by mixing patterns or environmental conditions that I have not fully accounted for yet.

In addition to analyzing these results, I have decided to expand my sampling locations. I plan to test streams near semiconductor plants and around the Dulles area to see whether proximity to potential industrial sources affects PFAS concentrations. Up to this point, I have mainly focused on variability within a single water body, but this will allow me to start exploring how location itself might play a role.