wasp7 course organic chemical model summary of process equations and model input data

Organic Chemical ModelOrganic Chemical Model

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

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

WASP7 Course

Aquatic Transport, Speciation and Aquatic Transport, Speciation and Transformation ProcessesTransformation Processes


WASP7 Course

TOXI Organic Chemical ProcessesTOXI Organic Chemical Processes• Equilibrium ProcessesEquilibrium Processes

– Sorption– Ionization

• Kinetic ProcessesKinetic Processes– Volatilization– Photolysis– Hydrolysis– Bacterial Degradation– Oxidation– Reduction


WASP7 Course

Sorption - DesorptionSorption - Desorption• ReactionReaction

– Movement of chemical between the dissolved phase and particulate or solid phase. The chemical may be physically associated or chemically bound to functional groups on the solid.

• Linear Partitioning EquationLinear Partitioning Equation• DataData

– Partition coefficient (Kp, Koc, or Kow), Lw/kgS

– Solids concentration, mg/L– Solids organic fraction

psw KSCSC ,

kgLLmgkgmg

pws KCC


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IonizationIonization• ReactionReaction

– Dissociation of neutral parent molecule into ionic species– Weak acid − Weak base

• Equilibrium EquationsEquilibrium Equations

• Data Data – pKai, negative log of Kai

– pKbi, negative log of Kbi

– pH, negative log of [H+]

aiKHRCOORCOOH , biKOHRROH ,

HKCC ai0 OHKCC bi

0


WASP7 Course

VolatilizationVolatilization

• DataData– Atmospheric concentration, g/m3

– Depth (surface area/volume), m– Henry’s Law constant, atm/molar– Water temperature, kelvin– Conductivity, kv, m/day

• Function of depth, current velocity and wind speed, m/sec

K

aw

vw

TRH

CC

D

k

t

C

• ReactionReaction– Movement of dissolved

chemical between water and air

• Kinetic EquationKinetic Equation


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PhotolysisPhotolysis

• DataData– Surface photolytic rate constant, kps, day-1

– Latitude and reference latitude, degrees– Light intensity at surface– Depth (surface area/volume), m– Light extinction coefficient, m-1

• Measured, or function of chl a, DOC, S

wPw Ckt

C

• ReactionReaction– Degradation of dissolved

chemical by sunlight

• KineticKinetic

EquationEquation

PlightCw


WASP7 Course

HydrolysisHydrolysis• ReactionReaction

• Kinetic Kinetic EquationEquation

• DataData– pH– kH or kHn, day-1

– kHa, molar-1day-1

– kHb, molar-1day-1

OHKKHKk HbHnHaH

'

'3

'2

PPOHCCatalysisBase

PPOHCCatalysisAcid

PPOHCNeutral

Ckt

CH


WASP7 Course

Bacterial DegradationBacterial Degradation

• ReactionReaction

• Kinetic Kinetic

EquationEquation

• DataData– kBW or kBS, day-1

– kB, (cells/mL)-1day-1

– bacterial population density, bac, (cells/mL)

isegBBSBWB backorkkk ,,

'' PbacteriaCmentSediBenthic

PbacteriaCColumnWater

sed

wc

Ckt

CB


WASP7 Course

OxidationOxidation


• KineticKinetic

EquationEquation

• DataData– kOX, day-1

– kO, (moles/L)-1day-1

– oxidant concentration, oxrad, (moles/L)

isegOOX oxradkk

PoxidantC

Ckt

COX


WASP7 Course

ReductionReduction


• KineticKinetic

EquationEquation

• DataData– kEX, day-1

– kE, (moles/L)-1day-1

– reductant concentration, exrad, (moles/L)

isegEEX exradkk

PreductantC

Ckt

CEX


WASP7 Course

Organic Toxicant Time FunctionsOrganic Toxicant Time Functions

• Water temperature (4) (degrees C)Water temperature (4) (degrees C)• Water velocity (4) (m/sec)Water velocity (4) (m/sec)• pH of water column & benthic segmentspH of water column & benthic segments• Normalized light intensity (photolysis option 2)Normalized light intensity (photolysis option 2)• Wind speed at 10 meters (m/sec)Wind speed at 10 meters (m/sec)• Bacteria population (Water & Benthos)Bacteria population (Water & Benthos)• Air temperature (degrees C)Air temperature (degrees C)• Reaeration rate constant (dayReaeration rate constant (day-1-1))• Chlorophyll-a (mg/L)Chlorophyll-a (mg/L)


WASP7 Course

Organic Toxicant Segment ParametersOrganic Toxicant Segment Parameters• Water velocity time function pointerWater velocity time function pointer• Water temperature (time function pointer and multiplier)Water temperature (time function pointer and multiplier)• Wind speed multiplierWind speed multiplier• Reaeration rate multiplierReaeration rate multiplier• Dissolved organic carbon, DOC (mg/L)Dissolved organic carbon, DOC (mg/L)• Fraction organic carbon for solids 1, 2, 3 (fraction)Fraction organic carbon for solids 1, 2, 3 (fraction)• Chlorophyll a concentration (mg/L)Chlorophyll a concentration (mg/L)• pHpH• Light extinction coefficient (meterLight extinction coefficient (meter-1-1))• Bacteria Population (cells/100 mL)Bacteria Population (cells/100 mL)• Oxidative radical concentration (moles/L)Oxidative radical concentration (moles/L)• Extra environmental property (e.g., reductant, moles/L)Extra environmental property (e.g., reductant, moles/L)• Overall decay rate constant for chemicals 1, 2, 3 (dayOverall decay rate constant for chemicals 1, 2, 3 (day -1-1))


WASP7 Course

Organic Toxicant ConstantsOrganic Toxicant Constants

• Constants GroupsConstants Groups– Solids– Ionization– Sorption– Volatilization– Hydrolysis– Photolysis– Biodegradation– Oxidation– Reduction

• Notes on ListingNotes on Listing– Constants are listed by

group for Non-Ionic Toxicant module

– In the general Organic Toxicant Module, these constants are repeated for each of 5 ionic species

– Chemical 1 constants are shown; these are repeated for chemicals 2 and 3


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Sorption ConstantsSorption Constants


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Volatilization ConstantsVolatilization Constants


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Hydrolysis ConstantsHydrolysis Constants


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Hydrolysis Constants, cont’dHydrolysis Constants, cont’d


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Photolysis ConstantsPhotolysis Constants


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Biodegradation ConstantsBiodegradation Constants


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Oxidation ConstantsOxidation Constants


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Reduction ConstantsReduction Constants


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Ionization ConstantsIonization Constants


WASP7 Course

Additional Additional Oxidation Oxidation Constants Constants for Ionic for Ionic

ChemicalChemical

wasp7 course organic chemical model summary of process equations and model input data

Documents

molesl slide

cellsml slide

atmmolar water temperature

degrees c water

negative log of h slide

model input data slide

s solids concentration

transformation processes