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THE ORIGIN AND AGE OF SPRING WATERS IN THE ST JOHNS RIVER WATER MANAGEMENT DISTRICT, CENTRAL FLORIDA. by David J. Toth, Ph.D., P.G. St Johns River Water Management District Brian G Katz, Ph.D., P.G. U. S. Geological Survey. PURPOSE. - PowerPoint PPT Presentation
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THE ORIGIN AND AGE OF SPRING WATERS IN THE ST
JOHNS RIVER WATER MANAGEMENT DISTRICT,
CENTRAL FLORIDA
by
David J. Toth, Ph.D., P.G.St Johns River Water Management
District
Brian G Katz, Ph.D., P.G.U. S. Geological Survey
PURPOSE
Determine the origin and age of water discharging from 11 springs in the St. Johns River Water Management District
Study Area (In SJRWMD)
Fig. 1 Study Area
D U
D
U
Spring Nitrate-N (mg/l) Delta nitrogen-15 (ppt)Wekiwa 0.89 8.6Palm 0.52 7.8Sanlando 0.25 11.7Starbuck 0.22 12.9Rock 1.29 5.8Juniper 0.07Ponce de Leon 1.14 8.9Alexander 0.03Silver Glen 0.03Blue 0.24Salt 0.09
Fig. 2 Thickness of the Confining Unit
Fig 3. Elevation of the Floridan Aquifer
Fig 4. Thickness of the MSCU
Fig 5. Elevation of the Top of the Lower Floridan Aq.
SODIUM CHLORIDE
CALCIUM BICARBONATE
SODIUM CHLORIDE,CALCIUM BICARBONATE
Fig 6. Water Quality
Fig 7. May 2001 Pot Surface
REACTIONSCALCIUM BICARBONATE
SPRINGS
Rain Water + a CH2O + b CaCO3 + c CaMg(CO3)2 + d O2 =
Spring Water
REACTIONSSODIUM CHLORIDE SPRINGS
Rain Water + Lower Floridan Water + a CH2O + b CaCO3 + c CaMg(CO3)2 + d O2 = Spring Water
Upper Floridan Water + Lower Floridan Water + b CaCO3 = Blue Spring
Upper Floridan Water + Lower Floridan Water = Salt Springs
REACTIONSSODIUM CHLORIDE,
CALCIUM BICARBONATE SPRING
Rain Water + Lower Floridan Water + a CH2O + b CaCO3 + c CaMg(CO3)2 + d O2 = Spring Water
Spring Computed C-13 Observed C-13 Observed-ComputedWekiwa -10.54 -10.52 0.02Palm -11.43 -11.2 0.23Sanlando -11.41 -10.87 0.54Starbuck -10.93 -10.84 0.09Rock -9.25 -9.44 -0.19Juniper -9.5 -10 -0.50Ponce de Leon -9.88 -8.4 1.48Alexander -10.24 -9.57 0.67Silver Glen -6.98 -8.15 -1.17Blue -11.25 -10.61 0.64Salt -8.75 -8.73 0.02
Spring Percent Lower FloridanAlexander 9.5Silver Glen 15.7Blue 15.7Salt 53.0Ponce de Leon 3.5
Spring Average Residence Time (yrs)Wekiwa 14Starbuck 18Palm 19Rock 21Blue 22Ponce de Leon 22Sanlando 23Juniper 25Alexander 25Silver Glen 26Salt 32
Error + or - 1
CONCLUSION
Water discharging from these springs are locally derived and contain variable amounts of recently recharged water.