Research has shown that during hurricane seasons, rising sea levels allow storms to push more seawater inland. As a result, freshwater sources such as rivers, lakes, and streams may experience a rise in salinity. The following study was conducted at Whitney Laboratory for Marine Biosciences of the University of Florida.
Measuring levels of dissolved organic carbon (DOC), Dissolved Oxygen (DO), and pH can illustrate how the slow, yet certain, sea level rise may affect an ecosystem’s water quality. For this experiment, soil cores were taken from two locations: Freshwater area and a Juncus romerianus (a brackish water plant) area. Furthermore, six total jugs of water (two jugs per site) were collected from three different (freshwater, brackish water, and seawater) sites. A multifactorial experiment was set-up to observe possible changes occurring in soil flux due to salinity change over time. For this experiment, the various water treatments were poured over previously cored soil. Over two weeks, at each predetermined time period for sampling, the DO and pH of every core was taken. The samples were then acidified to halt further decomposition and refrigerated. Lastly, they were tested for nitrogen and DOC using the Shimadzu TOC/ TN Analyzer (TOC-L) for analysis.
Results/Conclusions
Over time, a steady decrease was seen in DO levels of water treatments in Juncus soil; as compared to the other water treatments in freshwater soil, where oscillations were seen in DO levels. This is believed to be due to the effects of the consumption of oxygen by aerobic bacteria. Results for pH in each water treatment, for both soil locations, were also graphed in Microsoft Excel 360. It was observed that pH in freshwater soil cores exhibited a slightly decreasing concentration trend. This is in opposition to what was seen in pH in Juncus cores, which followed a slight increasing trend. However, the trends in both locations both had a steady change over time. This could be due to salt concentrations in the locations the samples were taken. While dissolved organic carbon concentrations are a lot higher than dissolved nitrogen, there is still a slight decrease in DOC over time and dissolved nitrogen increased greatly over the course of the experiment. As cores were inundated for longer time periods and oxygen levels decreased, microbial decomposition occurred slower over time, possibly explaining the decrease in DOC during the course of the experiment.