watershed & water quality modeling technical support center wasp7 course metals modeling summary...

Watershed & Water Quality Modeling Technical Support CenterWatershed & Water Quality Modeling Technical Support Center

WASP7 Course

Metals ModelingMetals Modeling

Summary of Process Equations Summary of Process Equations and Model Input Dataand Model Input Data

WASP7 Course


Summary of Significant Heavy Summary of Significant Heavy Metal ReactionsMetal Reactions

MetalMetal AsAs BaBa CdCd CuCu HgHg PbPb SeSe ZnZn

Anion ExchangeAnion Exchange

Sorption PotentialSorption Potential

Acid-Base HydrolysisAcid-Base Hydrolysis Complexation: Complexation:

with Inorganic Ligandswith Inorganic Ligands

with Organic Ligandswith Organic Ligands

Oxidation, Reduction Oxidation, Reduction (kinetic)(kinetic)

Methylation Methylation (kinetic)(kinetic)

From Schnoor, et al., 1987.

WASP7 Course


Speciation of Metals in Aquatic EnvironmentSpeciation of Metals in Aquatic Environment

Free Ion

Total Metal

Soluble Complexes with Organic Ligands

Precipitates

Adsorbed Species

• Adsorption/Coprecipitation on hydrous iron/manganese oxides

•Ion Exchange

•Adsorption to clays, silicates, other minerals

•Adsorption to organic solids

Soluble Complexes with Inorganic Ligands

From Felmy, et al., 1985.

WASP7 Course


Metals AdsorptionMetals Adsorption

• An “adsorption reaction” is a reaction An “adsorption reaction” is a reaction between a solute ion and a functional between a solute ion and a functional group (site) on a solid surface.group (site) on a solid surface.

• Important in attenuating dissolved metal Important in attenuating dissolved metal concentration.concentration.

• Use MINTEQA2 with adsorption reactions Use MINTEQA2 with adsorption reactions to calculate the distribution coefficient to calculate the distribution coefficient between adsorbed and dissolved phases.between adsorbed and dissolved phases.

From Allison and Allison, 2004. MINTEQ course notes.

WASP7 Course


Adsorption in MINTEQA2Adsorption in MINTEQA2

• Are analogous to coordination reactions in Are analogous to coordination reactions in solution.solution.

• Obey mass laws (mass action)Obey mass laws (mass action)• Include both physical and chemical solute-Include both physical and chemical solute-

surface interactions (van der Waals forces, surface interactions (van der Waals forces, electrostatic attraction, valency forces).electrostatic attraction, valency forces).

• Can be written as chemical “reactions” Can be written as chemical “reactions” regardless of the mechanism.regardless of the mechanism.

• Are thermodynamically distinct from solution Are thermodynamically distinct from solution reactions only when an electrostatic term is reactions only when an electrostatic term is computed and applied separately.computed and applied separately.

In MINTEQA2, adsorption reactions:


WASP7 Course


Adsorption Options in MINTEQA2Adsorption Options in MINTEQA2

• Linear Partitioning modelLinear Partitioning model

• Freundlich IsothermFreundlich Isotherm

• Langmuir IsothermLangmuir Isotherm

• Surface Complexation models:Surface Complexation models:– Diffuse layer (i.e., MIT Two-Layer model)– Constant Capacitance– Triple Layer

• Ion Exchange modelIon Exchange modelFrom Allison and Allison, 2004. MINTEQ course notes.

WASP7 Course


Linear, Freundlich, and Langmuir Linear, Freundlich, and Langmuir Equations for: Equations for:

• Linear Partitioning:Linear Partitioning:– Activity Kd Model

• Freundlich Isotherm:Freundlich Isotherm:– Activity Freundlich Model

• Langmuir Isotherm:Langmuir Isotherm:

XM

MXK actf '

,

MXXM

MK

MK

actL

actL

,

,max 1


XM

MXK actd '

,

WASP7 Course


Sorption Model ComparisonSorption Model ComparisonComparison of Linear, Freundlich, & Langmuir Isotherms

(after Stumm and Morgan, 1996; Morel, 1983)


WASP7 Course


Lumped Metals Partition EquationLumped Metals Partition Equation

Adsorbed Species

• Adsorption/Coprecipitation on hydrous iron/manganese oxides

•Ion Exchange

•Adsorption to clays, silicates, other minerals

•Adsorption to organic solids

Free Ion

Total Metal

Soluble Complexes with Organic Ligands

PrecipitatesSoluble Complexes

with Inorganic Ligands

Cd, mg/L

Cs, mg/L

d

sD CM

CK

M, kg/L

WASP7 Course


surface water

pore water

QIN

NPS QNPS

CNPS

adsorption/precipitation

desorption/dissolution

PS T or PS QT (hard inputs)

CT

depositionscourdispersion(calibration)

CD CP

CD CPbed sediment

QOUT

GW QGW hard input

CGW

Q

MPS

calibrationhigh flows( )

hard input or fcn of v and size

calibrationhigh flows( )

hard input inheadwaters( )

calibrationlow flows( )

(calibration)

adsorption

desorption

KD

KD

(calibration)

WASP Non-Reactive Metals Processes

From Caruso, 2005. CREM presentation

WASP7 Course


Selection of TOXI Module for Selection of TOXI Module for Simulating MetalsSimulating Metals

• Non-Reactive Metals: Non-Reactive Metals: Simple Toxicant ModuleSimple Toxicant Module

– Ag, Ba, Be, Cd, Co, Cu, Mo, Ni, Pb, Sb, Tl, V, Zn– As, Cr, Se, Sn (if redox kinetics data unavailable)

• Reactive Metals: Reactive Metals: Non-Ionizing Toxicant ModuleNon-Ionizing Toxicant Module

– As, Cr, Se, Sn (if redox kinetics data available)

• Mercury: Mercury: Mercury ModuleMercury Module

WASP7 Course


Metals Data SpecificationMetals Data SpecificationSimple Toxicant ModuleSimple Toxicant Module

• ConstantsConstants– Log 10 partition coefficient to DOC, log (L/kg)– Partition coefficient to silts and fines, L/kg– Partition coefficient to sands, L/kg– Partition coefficient to organic solids, L/kg

• ParametersParameters– Dissolved organic carbon, mg/L– Partition coefficient to silts and fines, L/kg– Partition coefficient to sands, L/kg– Partition coefficient to organic solids, L/kg

(KD values for constants, if any, take precedence over parameters)

WASP7 Course


Metals Data SpecificationMetals Data SpecificationNon-Ionizing Toxicant ModuleNon-Ionizing Toxicant Module

• ConstantsConstants– Log 10 partition coefficients to DOC, log (L/kg)– Partition coefficients (to silts and fines, to sands, and to

organic solids), L/kg– Oxidation rate constants (diss, sorb, DOC), M-1day-1 (or 1.0)– Oxidation mass yield coefficient (g/g)– Reduction rate constants (diss, sorb, DOC), M-1day-1 (or 1.0)– Reduction mass yield coefficient (g/g)

• ParametersParameters– Dissolved organic carbon, mg/L– Oxidant concentration, M, (or rate constant, day-1)– Reductant concentration, M, (or rate constant, day-1)


WASP7 Course

MetalMetal Soil*Soil* Suspended Suspended Matter*Matter*

Sediment*Sediment* DOC*DOC*

Ag(I)Ag(I) 1.0 / 1.0 / 2.62.6 / 4.5 / 4.5 4.4 / 4.4 / 4.94.9 / 6.3 / 6.3 2.1 / 2.1 / 3.63.6 / / 5.85.8

As(III,V)As(III,V) 0.3 / 0.3 / 3.43.4 / 4.3 / 4.3 2.0 / 2.0 / 4.04.0 / 6.0 / 6.0 1.6 / 1.6 / 2.52.5 / / 4.34.3

Ba(II)Ba(II) 0.7 / - / 3.40.7 / - / 3.4 2.9 / 2.9 / 4.04.0 / 4.5 / 4.5

Be(II)Be(II) 1.7 / 1.7 / 3.13.1 / 4.1 / 4.1 2.8 / 2.8 / 4.14.1 / 6.8 / 6.8

Cd(II)Cd(II) 0.1 / 0.1 / 2.92.9 / 5.0 / 5.0 2.8 / 2.8 / 4.74.7 / 6.3 / 6.3 0.5 / 0.5 / 3.63.6 / / 7.37.3

3.4 / 3.4 / 5.25.2 / / 5.55.5

Co(II)Co(II) -1.2 / -1.2 / 2.12.1 / 4.1 / 4.1 3.2 / 3.2 / 4.74.7 / 6.3 / 6.3 2.9 / 2.9 / 3.33.3 / / 3.63.6

2.9 / 2.9 / 4.54.5 / / 4.84.8

Partition Coefficients by Media(log KD in L/kg)

* Low / Median / HighFrom Allison and Allison, 2005


WASP7 Course



Cr (III)Cr (III) 1.0 / 1.0 / 3.93.9 / 4.7 / 4.7 3.9 / 3.9 / 5.15.1 / 6.0 / 6.0 - / - / 4.54.5 / - / -

Cr (VI)Cr (VI) -0.7 / -0.7 / 1.11.1 / 3.3 / 3.3

Cu(II)Cu(II) 0.1 / 0.1 / 2.72.7 / 3.6 / 3.6 3.1 / 3.1 / 4.74.7 / 6.1 / 6.1 0.7 / 0.7 / 4.24.2 / / 6.26.2

2.5 / 2.5 / 5.55.5 / / 7.07.0

Hg(II)Hg(II) 2.2 / 2.2 / 3.83.8 / 5.8 / 5.8 4.2 / 4.2 / 5.35.3 / 6.9 / 6.9 3.8 / 3.8 / 4.94.9 / / 6.06.0

5.3 / 5.3 / 5.35.3 / / 5.65.6

CHCH33HgHg++ 1.3 / 1.3 / 2.82.8 / 4.8 / 4.8 4.2 / 4.2 / 5.45.4 / 6.2 / 6.2 2.8 / 2.8 / 3.63.6 / / 5.05.0

Mo(VI)Mo(VI) -0.2 / -0.2 / 1.11.1 / 2.7 / 2.7 - / - / 2.52.5 / - / -

* Low / Median / High


From Allison and Allison, 2005


WASP7 Course



Ni(II)Ni(II) 1.0 / 1.0 / 3.13.1 / 3.8 / 3.8 3.5 / 3.5 / 4.64.6 / 5.7 / 5.7 - / - / 4.04.0 / - / - 4.7 / 4.7 / 5.15.1 / / 5.45.4

Pb(II)Pb(II) 0.7 / 0.7 / 4.24.2 / 5.0 / 5.0 3.4 / 3.4 / 5.65.6 / 6.5 / 6.5 2.0 / 2.0 / 5.15.1 / / 7.07.0

3.8 / 3.8 / 5.05.0 / / 5.65.6

Sb(III,V)Sb(III,V) 0.1 / 0.1 / 2.42.4 / 2.7 / 2.7 2.5 / 2.5 / 4.04.0 / / 4.84.8

2.7 / - / 4.32.7 / - / 4.3

Se(VI)Se(VI) -0.3 / -0.3 / 1.01.0 / 2.4 / 2.4 3.1 / - / 4.73.1 / - / 4.7 - / - / 3.63.6 / - / -

Sn(II)Sn(II) 2.1 / 2.1 / 2.92.9 / 4.0 / 4.0 4.9 / 4.9 / 5.65.6 / 6.3 / 6.3 - / - / 4.74.7 / - / -

Tl(I)Tl(I) 3.0 / 3.0 / 3.23.2 / / 3.53.5





WASP7 Course



V(V)V(V) 1.1 / - / 2.71.1 / - / 2.7

Zn(II)Zn(II) -1.0 / -1.0 / 3.13.1 / 5.0 / 5.0 3.5 / 3.5 / 5.15.1 / 6.9 / 6.9 1.5 / 1.5 / 3.73.7 / / 6.26.2

4.6 / 4.6 / 4.94.9 / / 6.46.4

CNCN-- 0.7 / 0.7 / 3.03.0 / 3.6 / 3.6




WASP7 Course


ReferencesReferences

• Allison, J.D., and Allison, T.L. 2004., MINTEQA2 Allison, J.D., and Allison, T.L. 2004., MINTEQA2 Geochemial Speciation Workshop. Allison Geoscience Geochemial Speciation Workshop. Allison Geoscience Consultants, Inc., Buford, GA.Consultants, Inc., Buford, GA.

• Allison, J.D., and Allison, T.L., 2005. Partition Allison, J.D., and Allison, T.L., 2005. Partition Coefficients for Metals in Surface Water, Soil, and Coefficients for Metals in Surface Water, Soil, and Waste. U.S. EPA, Athens, GA. EPA/600/R-05-074.Waste. U.S. EPA, Athens, GA. EPA/600/R-05-074.

• Caruso, B. S., 2005. Caruso, B. S., 2005. Modeling Metals Fate and Transport in the Upper Tenmile Creek Watershed Mining Area, Montana. CREM Presentation.

• Felmy, A. et al., 1985. MINTEQ – A Computer Program Felmy, A. et al., 1985. MINTEQ – A Computer Program for Calculating Aqueous Geochemical Equilibria. U.S. for Calculating Aqueous Geochemical Equilibria. U.S. EPA, Athens, GA. EPA/600/3-84-032.EPA, Athens, GA. EPA/600/3-84-032.

• Schnoor, J.L., et al., 1987. Processes, Coefficients, and Schnoor, J.L., et al., 1987. Processes, Coefficients, and Models for Simulating Toxic Organics and Heavy Metals Models for Simulating Toxic Organics and Heavy Metals in Surface Waters. U.S. EPA, Athens, GA. EPA/600/3-in Surface Waters. U.S. EPA, Athens, GA. EPA/600/3-87-015.87-015.

watershed & water quality modeling technical support center wasp7 course metals modeling summary...

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