The St. Johns river is classified as a class three water source, meaning it is appropriate for recreation, propagation, and maintenance of a healthy, well-balanced population of fish and wildlife. This is more commonly known as being safe for fishing and swimming (Maher, n.d.). Despite its classification, the St. Johns river has had several algae blooms that has killed off fish causing red tides. Algae blooms are caused by an excess amount of nutrients in the water, usually from anthropogenic (human) sources. One of the nutrients that has historically been a problem in the St. Johns river is nitrogen (Issues, n.d.).
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Nitrogen is naturally found in freshwater systems. Blue-green algae fix atmospheric nitrogen into nitrate, which aquatic plants need to survive. When aquatic plants either die or are digested by marine animals, nitrogen returns to the environment as ammonium. Bacteria oxidize ammonium into nitrite and then into nitrate, which is the most common form of nitrogen found in freshwater sources. Natural levels of nitrate in freshwater sources are typically less than 1 mg/L. Toxic levels of nitrate for both marine life and humans is anything above 10 mg/L, however, some fish species are sensitive to concentrations of nitrogen over 0.06 mg/L (Behar, 1997).
Sources of elevated levels of nitrate in the St. Johns include fertilizers, damaged septic tanks, storm water runoff, industrial waste, and wastewater treatments plants (Issues, n.d.). For my independent research project (IRP) I have chosen to investigate and measure the nitrate levels in two location on the St. Johns River, at Ed Stone Park, and Lake George. Are the nitrate levels at these two popular areas on the river really safe for fishing and swimming? Ideally, I would like to be able to take samples from the lower basin, upper basin, and a central part of the river, however, as you can see in the figure the St. Johns river is rather large and sampling those three areas wouldn't be feasible for me at this time. Instead, I chose to focus on popular fishing and recreation areas close to me.
Behar, S. (1997). Testing the waters: chemical and physical vital signs of a river. Retrieved February 9, 2017, from https://fosc.org/WQData/WQParameters.htm
Issues. (n.d.). Retrieved February 09, 2017, from http://www.stjohnsriverkeeper.org/issues#nutrients
Maher, J. R., P.E. (n.d.). Water quality and the st. johns river [PDF]. Department of Environmental Protection.
I like your nitrogen idea. How about doing a sampling transect on the Tomoka River? That's certainly closer and easier to access.
ReplyDeleteThat is a great idea. I will add that as one of my sites. Thank you for the suggestion.
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