Remediation of mercury in contaminated lakes: The Newcastle Reservoir demonstration project

Transcription

1 Remediation of mercury in contaminated lakes: The Newcastle Reservoir demonstration project D. Naftz and C. Angeroth, USGS, Salt Lake City, Utah R. Jackson, USGS, Urbana, Illinois J. Whitehead and S. Daly, UDEQ/DWQ, Salt Lake City, Utah C. Walker, UDNR/DWR, Salt Lake City, Utah N. Whittier, USGS, Cedar City, Utah

2 OUTLINE Problem Pre-deployment monitoring/modeling Pump deployment and operation Post deployment results

3 Data from Utah DWR Hg IN UTAH RESERVOIRS FDA limit

4 AQUATIC MERCURY CYCLE Krabbenhoft and Rickert (2005)

5 Hg REMEDIATION Utah regulatory agencies can t do much about controlling atmospheric sources of mercury, but may be able to do something about managing Hg methylation Rask and others, Biogeochemistry (2010) 101: Decreased volume of water with high methyl mercury Decreased surface area of low oxygen sediment

6 Exp. Control Exp. Control Exp. Exp. Control MeHg, ng/l DECREASE IN METHYL Hg Fish tissue (small perch, mm) Thermocline pumping (Rask and others, 2011) Water (epilimnion) X = X = Before During/after pumping pumping

7 DEPTH BELOW WATER SURFACE, IN METERS PRE-PUMPING CONDITIONS Outflow gage NCR-2 NCR-3 NCR-4 July 2010 NCR-2 NCR-3 NCR-4 MEHg:THg (MASS) MEHg:THg (MASS) MEHg:THg (MASS) DO 10 Inflow gage MeHg:THg = MeHg:THg DO, IN MG/L DO, IN MG/L DO, IN MG/L

8 DEPTH BELOW WATER SURFACE, IN M DEPTH BELOW WATER SURFACE, IN METERS NUTRIENT POOL AT DEPTH Outflow gage NCR-2 July 2010 Site NCR-2 CHLOROPHYLL A, IN G/L Chlorophyll a Temperature Orthophosphate Ammonia Nitrate + Nitrite Inflow gage PO 4 = 0.09; NO 3 = < PAR, IN MOLES S -1 M TEMP., IN DEG. C CONCENTRATION, IN MG/L

9 Hg SPECIES IN SEDIMENTS 2.6% Anoxic sediments Great Salt Lake wetlands Naftz and others, in review 2.7% 2.8% Hg total 2.1% Hg methyl

10 Hg SPECIES IN SEDIMENTS 4.4% Great Salt Lake wetlands Naftz and others, in review Enterprise Newcastle Hg total Hg methyl

11 SAMPLE DEPTH,IN METERS SAMPLE DEPTH,IN METERS SAMPLE DEPTH,IN METERS SAMPLE DEPTH,IN METERS SESTON PROFILES (Hg total ) July 2010 NCR-2 NCR m 0.2 m MeHg water = 0.16 ng/l MeHg water = 0.21 ng/l 0 to 11 m 0 to 10 m MeHg water = 0.53 ng/l MeHg water = 0.62 ng/l TOTAL Hg, IN UG/KG (DRY WEIGHT) TOTAL Hg, IN UG/KG (DRY WEIGHT) NCR-3 ENR m MeHg water = 0.20 ng/l 0.2 m MeHg water = 0.86 ng/l Plankton net 0 to 11 m 0 to 11 m MeHg water = 0.40 ng/l MeHg water = 4.50 ng/l TOTAL Hg, IN UG/KG (DRY WEIGHT) TOTAL Hg, IN UG/KG (DRY WEIGHT)

12 Model Objectives Simulate pumping of near bottom water to surface HYDRODYNAMIC MODEL Generalized Environmental Modeling System for Surfacewaters Simulate area of influence under different (1) pump rates; (2) pump positions; and (3) reservoir outflows m Bathymetric survey lines from AUV (1 day)

13 BOUNDARY CONDITIONS 15-minute weather station data (Enterprise, Utah) Daily water-level data (regression model) Inflow from Pinto Creek gage (15-minute data) Hourly reservoir outflow data Reservoir outflow Graphic of model grid and bathymetry Bottom layer elevation, in meters Simulated solar pump station Pump locations and rates inserted at various model grid points Inflow from Pinto gage

14 PUMPING INFLUENCE 1500 gpm 3000 gpm 6000 gpm High Hg pool High Hg pool High Hg pool Velocity, cm/sec No wind, pump inlet in bottom layer, reservoir outlet at bottom, vertical pipe inflow and outflow Position pump to the NE and migrate up reservoir (take advantage of bottom water removal from reservoir outflow)? Position closer to reservoir outflow for Hg removal?

15 NUTRIENT DISPERSION Simulation time Wind forcing off 1500 gpm pump rate Surface layer Simulation time Wind forcing on 1500 gpm pump rate Surface layer Dye concentration Dye concentration 20 day simulation 20 day simulation

16 Solar pump MODEL LAYER ELEVATION, IN METERS MODEL LAYER ELEVATION, IN METERS THERMOCLINE IMPACTS Profile fences 1642 Inner profile 1642 Outer profile Pump off Pump on Pump off Pump on TEMP., DEG. C TEMP., DEG. C 20-day pumping cools upper water column and warms lower water column relative to pump off simulation

17 Modified from SolarBee, Inc. Hg REMOVAL PROJECT Low DO bottom water PO 4, NH 3, NO 3, MeHg To irrigation pipeline Irrigated fields Solar-powered pump (SolarBee, Inc.) 1,500 gpm Reverse water flow (bottom up) Oxygenate bottom water, photodegrade MeHg, export nutrients, and??

18 SOLAR PUMP INSTALLED July 2011 Assembly Launch Positioning Attachment

19 SOLAR PUMP OPERATION 1,500 gpm total flow Operates 24-7, 365 days/year Remove algae from outflow Small surface footprint Low-noise operation Hazard light and perimeter chain Sulfide odor

20 THERMISTOR STRING 15-min sampling intervals Thermistors Pressure transducer Thermistor string, Newcastle Reservoir

21 WATER TEMPERATURE, IN DEG. C Pump on Temp. inversion POST-INSTALL TEMPERATURE Temperature increase near bottom m abv bot 0.5 m abv bot T-chain Solar pump Pump impacts thermal gradient /29 7/6 7/13 7/20 7/27 8/3 8/

22 DEPTH BELOW WATER SURFACE, IN M POST-INSTALL PROFILE 0 NCR-3 NCR-2 NCR-1 T-chain Solar pump m from pump 20 m from pump 42 m from pump Increasing depth of high ORP water near pump Low redox water moving to surface OXIDATION-REDUCTION POTENTIAL, IN MV Penetration of higher ORP water near pump

23 SUMMARY