Duncan & Alex

How Salinity of the Neponset River Changes as Distance From Boston Harbor Changes

Discussion:

We hypothesized that the salinity of the Neponset River would decrease as the distance from the Boston Harbor- which we considered to be open ocean- increases. Our results were consistent with this hypothesis which can be seen through the graph above. With an R^2 value of .95, we are very confident in our conclusion and the only possible outlier in our data came from location 10. An explanation of this outlier that aligns with the inaccuracy of the data trend is that we took the data in a boatyard right by The Rainbow Swash which is the large colorful water tower as you approach Boston from the south. This boatyard is located in a small nook of the Neponset River which could be considered an eddy and therefore is inconsistent with the rest of our data-taking locations which were out on open parts of the river. This site most likely was a spinning pool of slightly less saline water that became an eddy while flowing out to sea with the tide. Additionally, water from the boatyard could be more contaminated than at other parts of the river because of potential gas leakages which may slightly dilute the salinity reading. Another thing to note about this data is that all of it was collected at low tide where the salinity at each point will be much lower than if it was high tide. In the video, an example sample was collected at a relatively high tide. The sensor had the salinity at 1.6 ppt while in our data the salinity was only 0.3 ppt at location 2. This means that one of the most important control variables in this data collection process was to record each location a the same tide, because the salinity at one specific point changes throughout the day.

One of the most important implications of our project is to consider the human impact on the Neponset River and the ecosystem as a whole. Thinking about things like road salts, those can enter storm drains after periods of snow melt, which then, as we know, drains out into the Neponset River and local streams like Pine Tree Brook. Because Pine Tree Brook is a tributary of the Neponset River, an increase in salinity in Pine Tree Brook and the rest of the Neponset River Tributaries could result in an increase in salinity of the Neponset River. This could be a problem for the ecosystems around these tributaries and the Neponset because an increase in salinity could result in different organisms to die off or have to relocate. Although this is all speculation that is an extension of our work, we believe it is still very important to address how the anthroposphere can affect the environment around our campus and homes.