The Effect of Evapo-concentration on the Water Chemistry of Prairie Wetlands A PHREEQC Modeling Exercise by Vanessa O’Connor and David Mushet

Data Courtesy of National Climatic Data Center

WATER DEPTH (M) WETLAND P1 Data Courtesy of Dr. Don Rosenberry, U.S. Geological Survey Water Resources Division, Denver, Colorado

Photo Courtesy of U.S. Geological Survey, Northern Prairie Wildlife Research Center, Jamestown, North Dakota

Photo Courtesy of U.S. Geological Survey, Northern Prairie Wildlife Research Center, Jamestown, North Dakota

WATER DEPTH (M) WETLAND P1 Data Courtesy of Dr. Don Rosenberry, U.S. Geological Survey Water Resources Division, Denver, Colorado

SPRING Photo by D. M. Mushet

SUMMER Photo by D. M. Mushet

Recharge Flow Through Discharge Wetland Hydrological Functions T8 P1 P11

Constituent T8P1P11 May 14, 2001 EC μS/cm pH Alkalinity Ca Mg Na K SO Cl N P Cottonwood Lake Study Area Wetlands Beginning Concentrations (ppm) Data Courtesy of Dr. Jim LaBaugh, U.S. Geological Survey Water Resources Division, Reston, Virginia

SO 4 2- Cl - Na + + K + Ca 2+ Mg 2+ CO HC O 3 - Modified from Faure, G Principles and Applications of Geochemistry, Second Edition. Figure Prentice Hall, Upper Saddle River, New Jersey. P1 P11 T8 P1 P11

TITLE P1 Evapoconcentration (-95% H2O) SOLUTION 1 May 14, 2001, Starting Concentrations temp 21.2 pH 8.7 pe 4 redox pe units mg/l density 1 Ca 88.4 Mg Na 80.3 K 23.7 Cl P 0.15 N 3.4 Alkalinity S(6) water 1 # kg REACTION 1 H2O moles EQUILIBRIUM_PHASES 1 CO2(g) SAVE solution 2 END PHREEQC Program (part 1) One Liter of H 2 O is Approximately 55.5 moles This Code Removes 95% (52.73 moles) of the H 2 O For 25% evaporation, moles of H 2 O would be removed moles for 50% moles for 75% Etc.

TITLE Example 4b.--Factor of 20 more solution MIX SAVE solution 3 END PHREEQC Program (part 2) Solution 2 is now 0.05 kg (i.e., 5% of the 1kg Starting Solution) This code increases solution 2 by a factor of 20 to bring it back to the 1 kg standard For 25% evaporation (i.e., 0.75kg solution) solution 2 would be increased kg (50% evaporation) by kg (75% evaporation) by 4

ConstituentSolution 1Solution 2Solution 3 Mass of Water, kg Ca, mol2.21E E-02 Ca, mol/kg water2.21E E-02 EXAMPLE

Constituent Solution 1Solution 2Solution 3Solution 4Solution 5 May 14, % Evaporation 50% Evaporation 75% Evaporation 95% Evaporation Mass of water, kg pH Ca2.65E E E E E-03 Mg2.51E E E E E-03 Na6.09E E E E E-03 K5.99E E E E E-02 HCO E E E E E-02 SO E E E E E-03 Cl E E E E E-03 N2.36E E E E E-03 P1.74E E E E E-04 Cottonwood Lake Study Area Wetland T8

Constituent Solution 1Solution 2Solution 3Solution 4Solution 5 May 14, % Evaporation 50% Evaporation 75% Evaporation 95% Evaporation Calcite CaCO Aragonite CaCO Dolomite CaMg(CO 3 ) Gypsum CaSO 4 : 2H 2 O Anhydrite CaSO Halite NaCl Wetland T8 Solubility Indexes (SI)

Constituent Solution 1Solution 2Solution 3Solution 4Solution 5 May 14, % Evaporation 50% Evaporation 75% Evaporation 95% Evaporation Mass of water, kg pH Ca2.20E E E E E-02 Mg6.11E E E E E-01 Na3.50E E E E E-02 K6.07E E E E E-02 HCO E E E E E-02 SO E E E E-01 Cl E E E E E-02 N2.43E E E E E-03 P4.85E E E E E-05 Cottonwood Lake Study Area Wetland P1

Constituent Solution 1Solution 2Solution 3Solution 4Solution 5 May 14, % Evaporation 50% Evaporation 75% Evaporation 95% Evaporation Calcite CaCO Aragonite CaCO Dolomite CaMg(CO 3 ) Gypsum CaSO 4 : 2H 2 O Anhydrite CaSO Halite NaCl Wetland P1 Solubility Indexes (SI)

Constituent Solution 1Solution 2Solution 3Solution 4Solution 5 May 14, % Evaporation 50% Evaporation 75% Evaporation 95% Evaporation Mass of water, kg pH Ca1.42E E E E E-02 Mg4.61E E E E E-02 Na1.15E E E E E-01 K1.03E E E E E-02 HCO E E E E E-01 SO E E E E E-02 Cl E E E E E-02 N2.29E E E E E-03 P8.09E E E E E-04 Cottonwood Lake Study Area Wetland P11

Constituent Solution 1Solution 2Solution 3Solution 4Solution 5 May 14, % Evaporation 50% Evaporation 75% Evaporation 95% Evaporation Calcite CaCO Aragonite CaCO Dolomite CaMg(CO 3 ) Gypsum CaSO 4 : 2H 2 O Anhydrite CaSO Halite NaCl Wetland P11 Solubility Indexes (SI)

Photo Courtesy of U.S. Fish and Wildlife Service, Hailstone NWR, Lewistown, Montana Hailstone National Wildlife Refuge Soon After Dam Construction

Hailstone National Wildlife Refuge Soon As It Appears Today Photo Courtesy of U.S. Fish and Wildlife Service, Hailstone NWR, Lewistown, Montana

Photo Courtesy of U.S. Fish and Wildlife Service, Hailstone NWR, Lewistown, Montana