Kelly-Ann UR - What Do You Ask Yourself Before You Swim?

     Before you get into a freshwater source here in Florida, have you ever considered if it is safe?  Those of us living in Florida become accustomed to looking out for alligators, snakes, and other dangerous wildlife, however there are dangers we cannot see as well.  Nitrate, a nutrient naturally found in freshwater systems, can reach toxic levels due to anthropogenic enrichment.

Algae Bloom in 2005, St. Johns River

     The St. Johns river is the largest freshwater body in our area.  It has been classified as a class 3 water source, which means it is supposed to be safe for recreational use.  People do often fish, swim, and participate in other activities that put them within direct contact with the water of the river.  However, regular toxic algae blooms indicate that there may be elevated levels of nitrate in the river, since algae blooms are caused by high levels of nitrate and phosphorus.  Although the photo shown to the right is from 2005, there have been reports of toxic algae blooms as recently as last summer.  Naturally, nitrate levels tend to be less than 1 mg/L in freshwater sources.  Certain species of fish are sensitive to nitrate levels above 0.06 mg/L.  Levels above 10 mg/L are toxic to humans.  We know that excess nitrate is making its way into the St. Johns river due to the use of fertilizers, storm runoff, industrial waste, failing septic systems, and other human based sources.

St. Johns River Map

     Based on what is already known about the nitrate in the St. Johns river, I am investigating if the nitrate levels in the St. Johns river is safe for fish and human recreation. In order to answer my scientific question, I am going to be preforming a transect of the river, taking surface samples at five locations along the river: in Jacksonville, Green Cove Springs, Lake George, Lake Monroe, and the St. Johns Marsh.  I will be preforming the transect in the previously listed order, which follows the river from in the opposite direction of its flow.  I will be preforming the complete transect in one day.  The samples will be analyzed using method 1002l with a HACH DR/890 colorimeter to quantitatively measure total nitrate concentration.  I will visually present my data in a line graph, which shows changes in concentration of nitrate over distance.

Sources:
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.