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Collaborative Meeting on Modeling Mercury in Collaborative Meeting on Modeling Mercury in Freshwater EnvironmentsFreshwater Environments
January 19, 2006January 19, 2006Niagara Falls, NY Niagara Falls, NY
Overview of Watershed and Water Body Models for Mercury
used by the US EPA
Christopher KnightesChristopher KnightesUSEPA / ORD / NERL / ERD Athens, GAUSEPA / ORD / NERL / ERD Athens, GA
Wet Deposition
Hg2+
Dry DepositionHg2+(p,v)
Evasion (Hg0)
Resuspension
Runoff and Erosion
Litterfall and
Throughfall
Hg0
WatershedProcesses
Settling
Hg2+
MeHg
Diffusion
DryDeposition
Burial
Mercury in WatershedsAnd Water Bodies
Food WebTransformation
Ground Water?
MeHgHg2+
Primary1 and Support Models for Analysis of Mercury Fate
available from EPA - Athens
• SERAFM – Mercury Risk Screening Model
• WCS (MLM) – Watershed Loading Model
• GBMM – Grid-Based Watershed Loading Model
• WhAEM2000 – Groundwater Flow Model
• WASP7 – Water Body Pollutant Fate Model
• EFDC – Water Body Hydrodynamic Model
• BASS – Aquatic Food Web Model1 Simulates mercury explicitly.
Watershed Mercury Models
• Watershed Characterization System, Mercury Loading Module – WCS MLM Current available model Grid soil calculations, sub-watershed loading resolution Simple hydrology, erosion, mass balance Provides yearly-average concentrations, loads
• Grid-Based Mercury Model – GBMM Projected Availability: January 2006 Fine grid resolution Simple wetland and tributary transport and transformation
algorithms for mercury Provides daily concentrations, loads Future incorporation into BASINS toolkit
Water Body Mercury Models• SERAFM:
Process-based, Steady-State Lake/Pond Model Enhanced version of IEM-2M from Mercury Report to Congress Stand-Alone model developed for Risk Assessors Incorporates Watershed Runoff and Erosion, Mercury Cycle Chemistry,
Bioaccumulation, and Wildlife/Human Risk Values Provides yearly-average concentrations, loads Serves as a Repository for Updates in Mercury Science and Modeling
• WASP7 and WASP7 Mercury Module: Dynamic, Process Modeling Framework General design for modeling contaminant fate and transport in surface
waters Compartment Modeling Approach, Lakes/Ponds/Rivers Incorporates Mercury Module Is being updated to incorporate SERAFM Science Model architecture is being updated and improved
PamlicoSound
TrentRiver
ClubfootCreek
AdamsCreek South
River
E
Scale
10 km0
N
S
W
5 km
BeardCreek
SlocumCreek
HancockCreek
UpperBroadCreek Goose
Creek
SwiftCreek
BroadCreek
GreensCreek
DawsonCreek
BachelorCreek
WASP Mercury Module
VolatileExchangeof Hg(0)
Watershed and Atmospheric Loadsof Hg(II) and MeHg
State VariablesHg(0) SiltHg(II) SandMeHg Biotic SolidsMethylation
Demethylation Oxidation
Reduction
Burial
Point Source Loads of
Hg(II)
DOC
Mercury Watershed/Water Body Links
Watershed ModelsWCS-MLM
GBMM WARMF
Water Body ModelsWASP
SERAFM
Hydrodynamic ModelsEFDC
DYNHYDEPD-RIV1
BioaccumulationModelsBASSFCM-2
External Spreadsheets
ASCII FilesWindows Clipboard
Atmospheric Models
Brier Creek Mercury Modeling: WCS-MLM and WASP7
HgII in Soil
Tributaries
reduction,evasion
Atmospheric Wet and Dry Deposition
reduction,volatilization
Impervious Surface
volatilization
export
export
Water Surface
runoff
export
runoff and erosion
sediment layer
MeHg Hg(II) Hg0
Silt, POM water column Sand
Burial
Leaching
Mercury Reduction Benefits Analysis:Changes in Mercury Concentrations and
Evaluation of Response Times for Mercury Emission/Deposition Reductions
Applications of
SERAFM, WASP, WCS, and BASS
Eagle Butte, South Dakota Pawtuckaway Lake, New Hampshire
Lake Waccamaw, North Carolina Brier Creek, Georgia Lake Barco, Florida
Summary of Ecosystem CharacteristicsParameter Pawtuckaway
Lake, NHLake
Waccamaw, NCLake Barco,
FLEagle
Butte, SDBrier
Creek, GA
Watershed Area
50 km2 217 km2 0 4.2 km2 2,190 km2
Lake Area 3.64 km2 34.7 km2 0.12 km2 0.19 km2 n/a
Watershed/
Lake Ratio
13.7 6.3 0 22 n/a
Residence Time
165 days 241 days 0 0 12 days
Stratification Yes No No No No
Depth 5m 2.3m 3.7m 2.0m 0.3 – 2.0 m
pH Neutral Acidic Acidic Alkaline n/a
Trophic State Dystrophic Mesotrophic Oligotrophic Eutrophic n/a
Total Hg Dep 20.7 ug/m2/yr
29.2 ug/m2/yr
31.5 ug/m2/yr
19.8 ug/m2/yr
26.8 ug/m2/yr
Predicted vs Observed Fish Concentrations
2
2.5
3
3.5
2 2.5 3 3.5
Log Hg fish (ng/g) - Observed
Lo
g H
g f
ish
(n
g/g
) -
Pre
dic
ted
PawtuckawayLake
Lake Waccamaw
Lake Barco
Eagle Butte
Observed vs. predicted fish mercury concentrations in model ecosystems at steady state with no change in atmospheric loading. Straight line represents 1:1 relationship between observed and modeled results.
Fast: 1 cm sediment, D = 10-4 cm2/s
Medium: 2 cm sediment, D = 10-4 cm2/s
Slow: 3 cm sediment,
D = 5x10-5 cm2/s
Lake Barco, FL50% Loading Reduction
MMapsProportional Relationship
Representative Changes in Fish Concentrations in Response to
Emission/Deposition Reductions
Fast: 1 cm sediment, D = 10-4 cm2/s
Medium:2 cm sediment, D = 10-4 cm2/s
Slow: 3 cm sediment,
D = 5x10-5 cm2/s
Pawtuckaway Lake, NH50% Loading Reduction
MMapsProportional Relationship
Site SERAFM WASPFast Medium Slow Fast Medium Slow
Eagle Butte, SD 3 4 6 6 11 16
Pawtuckaway Lake, NH 80 125 >180 24 44 69
Lake Waccamaw, NC 3 6 12 10 15 17
Brier Creek, GA n/a n/a n/a 49 82 123
Lake Barco, FL 14 28 45 n/a n/a n/a
Sensitivity Range of Response Times
Current and Historical Applications by NERL-ERD Staff
• Steamboat Creek and Wetland Mesocosm near Reno, NV Scott Brown (MS Thesis at UNR) under advisement of Chris Knightes (SERAFM)
• Sudbury River, MA Chris Knightes (SERAFM, WASP7)
• Cheyenne Sioux Reservation Ponds, SD John Johnston (SERAFM)
• Five Representative Ecosystems: Brier Creek, GA; Lee Dam, SD; Pawtuckaway Lake, NH; Lake Barco, FL; Lake Waccamaw, NC. Robert Ambrose, Elsie Sunderland, Chris Knightes, John Johnston (WCS-MLM,
SERAFM, WASP7, BASS)• Vermont & New Hampshire Lakes
Chris Knightes (R-MCM)• Ogeechee, Canoochee, & Brier Creek River Basins, GA
Tim Wool, Chris Knightes & Robert Ambrose (WCS-MLM, WASP7)• Ochlockonee, Savannah, St. Mary’s, Satilla, Suwanee, GA
Tim Wool & Robert Ambrose (WCS-MLM, WASP7); Craig Barber (BASS)• Everglades, FL
Robert Ambrose, Craig Barber, Rochelle Araujo (WASP5, BASS)