Tetra Tech, Inc. · NASDAQ:TTEK
Tetra Tech — Technical Presentation (April 2010)
29 slides from Tetra Tech's technical presentation, Apr 28, 2010
Slide 1: Overview of TM6: Simulation of Selenium Fate and Transport in North San Francisco Bay
Overview of TM6: Simulation of Selenium Fate and Transport in North San Francisco Bay Limin Chen, Sujoy Roy, and Tom Grieb Tetra Tech, Inc., Lafayette, CA Presentation to TMDL Advisory Committee April 28, 2010
Slide 2: Overview
Overview Goal: Develop tool to calculate selenium in water and biota in response to different loads of selenium entering North San Francisco Bay Technical Review Process Modeling Approach Selenium Loads Example Calibration Results Predicted Loads and Concentrations Role of Boundary Conditions Model
Slide 3: Technical Review Committee (2007-2010)
Technical Review Committee (2007-2010) Dr. Nicholas S. Fisher, State University of New York, Stony Brook Dr. Regina G. Linville, California State Office of Environmental Health Hazard Assessment Dr. Samuel N. Luoma, Emeritus, U.S. Geological Survey Dr. John J. Oram, San Francisco Estuary Institute T
Slide 4: Model Structure
Model Structure Point Sources (Refineries, POTWs, Other Dischargers) Contribute to dissolved phase Estuary Water Column Dissolved species Organic Selenate Selenite Selenide DSe(VI) DSe(IV) DSe(-II) Total Particulate River and Tributary Selenium as a Uptake by Uptake by Loads Mix of Organic Selenate
Slide 5: Study Domain
Study Domain Red dots: approximate locations of model segments Yellow pins: sampling stations in Cutter and Cutter (2004) survey Model domain starts at Sacramento River at Rio Vista and extends to Golden Gate
Slide 6: Model Components and Steps in Calibration
Model Components and Steps in Calibration 1. Salinity: relatively conservative (advection and dispersion) 2. Total Suspended Material: three components of PSP, BEPS and phytoplankton, result of advection, dispersion 3. Phytoplankton (Chl a): result of advection, dispersion, growth, respiration, and
Slide 7: Modeling Steps
Modeling Steps During model calibration, adjustable parameters were varied to obtain a best fit to the data; for evaluation, the model was run with the fitted parameters and compared with new data sets Model calibrated to data from 1999, and tested against datasets from 2001, 2005, 1998 and 1986 Mod
Slide 8: Model Schematic
Model Schematic Point Sources, Tributaries, and South Bay Input Seawater Sacramento River Exchange at Rio Vista Golden Gate North San Francisco Bay San Joaquin River near Delta 1-D model with 33 well-mixed cells representing the bay.
Slide 9: Selenium Transformations
Selenium Transformations PSP Dissolved Species b Selenate+ Selenite , a’, Se(VI)+ Se(IV) es s /D Ad Selenate Elemental Se Se(VI) Up Se(0) tak e, k5 Organic Oxidation, k3 Selenide Se(-II) Selenite Uptake, k 4 Se(IV) Organic Phyto- Selenide plankton Advective/ Se(-II) k1 k Advective/ Dispersive n, ke,
Slide 10: Uptake by Bivalves
Uptake by Bivalves Se(IV) + Se(VI), particulate Se(-II), dCmss Se(0), particulate particulate dt = ku × Cw + AE × IR × Cf − ke × Cmss Time AE = 0.45 AE = 0.2 Time Cmss is selenium concentration in Time AE = 0.54 to 0.8 tissue (µg/g), ku is the dissolved metal uptake rate constant (L/g/d), Cw is the
Slide 11: Boundary Conditions are Important
Boundary Conditions are Important C Seawater boundary Riverine boundary Sources in the Bay 0 Distance 100 C, on the y-axis, represents a constituent being modeled. The model framework shown on the preceding slides involves the solution of a set of differential equations. These explain the shape of t
Slide 12: Annual Selenium Loads
Annual Selenium Loads Riverine (kg/yr) Refineries (kg/yr) Tributaries (kg/yr) 10000 8000 Selenium loads (kg/yr) 6000 4000 2000 0 1985 1990 1995 2000 2005 Year
Slide 13: Dissolved Loads for Water Year 1999
Dissolved Loads for Water Year 1999 SJR @ Vernalis 2666 7% Delta 365 South Bay 1607 176 SJR @ confluence POTWs 32% 3% Sac. River @ Rio Vista Bay Exchange with Ocean Water 1502 5034 30% Tributaries Refineries 820 559 16% 11%
Slide 14: Particulate Loads for Water Year 1999
Particulate Loads for Water Year 1999 SJR @ Vernalis 652 Delta 78 0 SJR @ confluence POTWs 11% Sac. River @ Rio Vista Bay Exchange with Ocean Water 465 ~ 754 804 (32 BEPS) 89% Tributaries Refineries Bed Exchange 0 0 0.1
Slide 15: Example Calibration 1: Salinity (1999)
35 r = 1.00 Jan 21, 1999 r = 0.99 August 17, 1999 Example 30 GOF = 97.0% GOF = 98.5% 25 Salinity (psu) 20 15 10 Calibration 1: 5 0 35 Salinity (1999) r = 0.98 r = 1.00 ∑ Xcal − ∑ Xobs 30 GOF = 99.6% April 14, 1999 Sep 14, 1999 GOF = 94.9% 25 GOF (%) = 100 * 1 − ∑ Xobs ∑ Xcal Salinity (ps
Slide 16: Example Calibration 2: Chlorophyll a (1999)
12 12 Jan 21, 1999 r = 0.31 August 17, 1999 r = 0.45 10 8 GOF = 68.5% 10 8 GOF =66.8% Example µ g/L) Calibration 2: Chl a (µ 6 6 4 4 2 0 0 2 Chlorophyll a 12 12 10 April 14, 1999 r = 0.09 GOF = 95.2% 10 Sep 14, 1999 r = -0.04 GOF = 48.2% (1999) 8 8 µg/L) Chl a (µ 6 6 4 4 2 2 0 0 12 12 r = 0.40 r = 0
Slide 17: Example Calibration 3: Dissolved Selenium (1999)
0.10 0.08 r = 0.164 GOF= 95.0% Example Selenite (µg/L) 0.06 Calibration 3: 0.04 0.02 Dissolved 0.00 0 5 10 15 20 25 30 35 Selenium (1999) Salinity 0.10 r = 0.192 GOF = 78.3% 0.08 Selenate (µg/L) 0.06 0.04 0.02 0.00 0 5 10 15 20 25 30 35 Salinity 0.10 r = 0.353 GOF = 95.8% 0.08 Org. Selenide (µg/L) 0
Slide 18: Example Calibration 4: Particulate Selenium (1999)
0.025 Part. SeIV+SeVI (µg/L) 0.020 r = 0.801 GOF = 92.1% Example 0.015 Calibration 4: 0.010 0.005 Particulate 0.000 0 5 10 15 20 25 30 35 Selenium (1999) Salinity 0.025 r = 0.676 0.020 GOF = 83.5% Part. Se0 (µg/L) 0.015 0.010 0.005 0.000 0 5 10 15 20 25 30 35 Salinity 0.025 r = -0.021 GOF = 73.5% 0.
Slide 19: TSM Long-Term Evaluation at USGS Stations
TSM Long-Term Evaluation at USGS Stations 250 250 STN 3 Observed STN 14 Observed Simulated Simulated 200 200 TSM (mg/l) TSM (mg/l) 150 150 100 100 50 50 0 0 1998 2000 2002 2004 2006 2008 2010 1998 2000 2002 2004 2006 2008 2010 250 250 STN 6 Observed STN 18 Observed Simulated Simulated 200 200 TSM (m
Slide 20: Evaluation of Chlorophyll a
Evaluation of Chlorophyll a 20 50 STN 3 Observed STN 14 Observed 18 Simulated Simulated 16 40 14 Suisun Bay San Pablo Bay µg/l) 12 µg/l) 30 Chl a (µ Chl a (µ 10 8 20 6 4 10 2 0 0 1998 2000 2002 2004 2006 2008 2010 1998 2000 2002 2004 2006 2008 2010 20 20 STN 6 Observed STN 18 Observed 18 18 Simulate
Slide 21: Predicted Particulate Selenium Concentrations (1999)
November 11, 1999 Predicted Particulate 0.8 0.7 Observed Part. SeIV + SeVI (µg/g) Predicted 0.6 0.5 0.4 Selenium Concentrations 0.3 0.2 (1999) 0.1 0.0 0 5 10 15 20 25 30 35 0.8 0.7 0.6 Part. Se0 (µg/g) 0.5 0.4 0.3 0.2 0.1 0.0 0 5 10 15 20 25 30 35 0.8 0.7 0.6 Part. SeII (µg/g) 0.5 0.4 0.3 0.2 0.1 0.
Slide 22: Bivalve (C. amurensis) Concentrations
Bivalve (C. amurensis) Concentrations 25 Observed IR = 0.45, AE = 0.2,0.45, 0.8 IR = 0.65, AE = 0.2, 0.45, 0.8 20 IR = 0.65, AE = 0.2, 0.45, 0.54 IR = 0.85, AE = 0.2, 0.45, 0.80 Cmss (µg/g) 15 10 5 0 1998 1999 2000 2001 2002 2003 2004 2005 2006 Year
Slide 23: White Sturgeon Concentrations
White Sturgeon Concentrations Suisun Bay San Pablo Bay Estuary Mean 50 Muscle selenium concentration (µg/g) 40 TTF = 1.7 30 20 10 0 80 85 90 95 00 05 10 Year
Slide 24: Effect of Changing Boundary Conditions
Effect of Changing Boundary Conditions Observed Lower Boundary Higher Boundary 1.8 1.6 1.4 Selenium (µg/g) 1.2 Particulate 1.0 0.8 0.6 0.4 0.2 0.0 0 5 10 15 20 25 30 35 Salinity
Slide 25: Scenarios Examined
Scenario Description Scenarios 1 2 Base case Removal of all point source loads (refineries, POTWs), and local tributary loads Examined 3 30% reduction in refinery and San Joaquin River loads, dissolved only 4 50% reduction in all point sources (refineries, POTWs), local tributaries and San Joaquin R
Slide 26: Impact on Dissolved Se
High Flow Month (April, 1999) 0.3 Impact on Dissolved Se (µg/l) 0.2 Dissolved Se 0.1 0.0 0 1 2 3 4 5 6 7 8 9 10 Low Flow Month (November, 1999) 0.2 Dissolved Se (µg/l) 0.1 0.0 0 1 2 3 4 5 6 7 8 9 10 Dry Year Dry Month (July, 2001) 0.2 Dissolved.Se (µg/l) 0.1 0.0 0 1 2 3 4 5 6 7 8 9 10
Slide 27: Impact on Particulate Se
High Flow Month (April, 1999) 2.0 Impact on 1.5 Part. Se (µg/g) 1.0 Particulate Se 0.5 0.0 0 1 2 3 4 5 6 7 8 9 10 Low Flow Month (November, 1999) 2.0 1.5 Part. Se (µg/g) 1.0 0.5 0.0 0 1 2 3 4 5 6 7 8 9 10 Dry Year Dry Month (July, 2001) 2.0 1.5 Part. Se (µg/g) 1.0 0.5 0.0 0 1 2 3 4 5 6 7 8 9 10
Slide 28: Summary of Model Results
Summary of Model Results The model is able to simulate key aspects of physical and biological constituents that affect selenium concentrations. During calibration, the model was able to fit the patterns in concentrations of dissolved and particulate selenate and selenite well, although it performed
Slide 29: Impact on Bivalve Se
High Flow Month (April, 1999) 35 30 Impact on 25 Cmss Se (µg/g) 20 15 Bivalve Se 10 5 0 0 1 2 3 4 5 6 7 8 9 10 Low Flow Month (November, 1999) 35 30 25 Cmss Se (µg/g) 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 10 Dry Year Dry Month (July, 2001) 35 30 25 Cmss Se (µg/g) 20 15 10 5 0 0 1 2 3 4 5 6 7 8 9 10