# Chemical Distribution, Fate and 

# Transport in the Environment
September 10, 2014 Jaeshin Kim and Gary E. Kozerski Dow Corning Corporation

# Acknowledgement

• Dr. David E. Powell (Dow Corning Co.)

• Dr. Don Mackay and Lauren Hughes (Trent University, Canada)

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# Outline

• Background: Why do we need multimedia models?

• Introduction to the EQC model and recent update

• Applications of New EQC model

• Summary

# What Do We Want to Know?

Distribution and 

## important fate processes for different chemicals 

## Overall persistence (P) Environmental 

## concentrations and exposures
Potential for long range transport (LRT) Bioaccumulation in

organisms and food webs Evaluation of likely 

## recovery times of contaminated environments


## Checking the consistency of monitoring data 

## Screening and prioritizing chemicals Documenting the sources 

## and nature of contamination and feasible remedial strategies

4

## Without Modeling 

# Why Do We Need Multimedia Modeling?

5 

### Chemical Fate, Transport & Distribution 

## Chemical Properties Environment

Properties Emissions

Scenarios

Environmental Exposure Difficult to survey the set of properties

and predict environmental behaviors of

chemicals Difficult to conceive how environmental assessments can be done consistently and openly without modeling

# The EQC (Equilibrium Criterion) Model (Mackay et al. 1996)

6 Mackay D., S. Paterson , A. Di Guardo, and C.E. Cowan. 1996. Evaluating the environmental fate of types of chemicals using th e E QC model. Environ. Toxicol. Chem. 15:1627

- 1637. McKone T.E. 1993. CalTox, a multi

- media total

- exposure model for hazardous waste sites part II the dynamic multi

- media transport and transformation model. A report prepared for the State of California, Department Toxic Substances Control by the Lawrence Livermore National Laborat ory No. UCRL

- CR

- 111456PtII. Livermore, CA. EC (1996). EUSES, the European Union System for the Evaluation of Substances. National Institute of Public Health and the Env iro nment (RIVM), the Netherlands. Available from the European Chemicals Bureau (EC/JRC), Ispra, Italy. 

# • Based on fugacity
- based mass balance

• Prediction of mass distribution, persistence and rates of transport 

# and transformation

• Not site - specific but an evaluative standard environment

• Internationally used for regulation purposes

• Imbedded in EPI SuiteTM (US EPA)

– “Fugacity” Tab



# • Similar models

– CalTox (McKone et al. 1993)



## – SimpleBox (EUSES, EC 1996)

# Level 1: Equilibrium

7 

## Soil 

## Air

Water

Sediment No degrading reactions No advective processes No intermedia transport processes The equilibrium distribution of a fixed quantity of conserved chemical, in a closed environment at equilibrium

# Level 2: Steady
- state and Equilibrium

8 

## Soil 

## Air

Water

Sediment

A

A

A R

R

R R E 

## A chemical is continuously discharged at a constant rate and achieves a steady

- state and equilibrium condition at which the input and output rates are equal.

Degrading reactions and advective processes are the loss or output processes treated. Intermedia transport processes (e.g. wet deposition, or sedimentation) are not quantified.

# Level 3: Steady
- state and Non
- Equilibrium

9 

## Soil 

## Air

Water

Sediment

A

A

A R

R

R R E E

E 

## A chemical is continuously discharged at a constant rate and achieves a steady state condition in which input and output rates are equal.

The loss processes are degrading reactions and advection. A mass balance applies to the system as a whole, as well as to each compartment. 

### Rates of intermedia transport are calculated using D values which contain information on mass transfer coefficients, areas, deposition and resuspension rates, diffusion rates, and soil runoff rates.

# EQC Model Update

• More flexible input entries

– Chemical properties

– Emission scenarios

– Sensitivity/uncertainty analysis



# • Spreadsheet platform



# • Publically available at CEMC website

– http://www.trentu.ca/academic/aminss/envmodel/models/NewEQCv101.html



# • Publications

– Hughes, Lauren, Don Mackay, David E. Powell, and Jaeshin Kim. 2012. An updated state of the science EQC model for evaluating chemical fate in the environment: Application to D5 (decamethylcyclopentasiloxane). Chemosphere 87 (2):118

- 124.

– Kim, Jaeshin, David E. Powell, Lauren Hughes, and Don Mackay. 2013. Uncertainty analysis using a fugacity

- based multimedia mass

- balance model: Application of the updated EQC model to decamethylcyclopentasiloxane (D5). Chemosphere 93 (5):819

- 829.

10

# Applications of New EQC to Hypothetical Chemicals

1. An Easy - to - Test Compound 1. Non

- volatile 2. High water solubility 

# 2. A Difficult
- to - Test Compound, DTC1 1. Non

- volatile 

## 2. Low water solubility 3. High Log Kow and Log Koc 

# 3. A Difficult
- to - Test Compound, DTC2 1. Volatile 2. Low water solubility 3. Mid

- high Log Koc

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# Example 1: An Easy
- to - Test Compound

12



## Physico
- chemical properties Half
- lives (hr)

• Henry's Law constant: 9.38E

- 04 Pa·m3/mol

• Log Kow: 2

• Log Koc: 2



## • Log BCF: 2 • Air: 15.8

• Water: 360

• Soil: 720



## • Sediment: 3,240

Total Emission Initial Release

WWTP AIR (0%)

Sludge SOIL (4 %) Effluent WATER (96%) 

## Emission Scenario

100%

100% 0% 0%

100% 100%

4% 96%

# Example 1: An Easy
- to - Test Compound

13

Soil Air

Water

Sediment 0.005

329 kg/h

0.04 R

R

R R 960 kg/h 40 kg/h

3.51 kg/h Fugacity: 4.34E - 11 Pa Mass fraction: 0% Concentration: 4.56E - 12 g/m3

Fugacity: 5.31E - 9 Pa Mass fraction: 0.5% Concentration: 3.85E - 3 g/m3 Fugacity: 2.92E - 9 Pa Mass fraction: 10.3% Concentration: 2.11E - 13 g/m3 Fugacity: 6.17E - 9 Pa Mass fraction: 89.2% Concentration: 1.65E - 3 g/m3 0.11 kg/h

0.11 kg/h 0.03 kg/h 0.01 kg/h

1.89 kg/h 1.44 kg/h 36.5 kg/h 634 kg/h

0.41 kg/h 0.02 kg/h

Advection time: 1,121 h Reaction time: 550 h Overall persistence: 369 h Total emission: 1,000 kg/h Total mass: 3.69E5 kg

# Example 2: A Difficult
- to - Test Compound DTC1

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## Physico
- chemical properties Half
- lives (hr)

• Henry's Law constant: 2.35 Pa·m3/mol

• Log Kow: 7.2

• Log Koc: 6.8



## • Log BCF: 10,000 • Air: 2,450

• Water: 4,320

• Soil: 8,640



## • Sediment: 38,900

Total Emission Initial Release

WWTP AIR (0%)

Sludge SOIL (90%) Effluent WATER (10%) 

## Emission Scenario

100%

100% 0% 0%

100% 100%

90% 10%

# Example 2: A Difficult
- to - Test Compound DTC1

15

Soil Air

Water

Sediment 0.22

24.7 kg/h

38.1 R

R

R R 100 kg/h 900 kg/h

1.14 kg/h Fugacity: 6.18E - 10 Pa Mass fraction: 0% Concentration: 2.19E - 10 g/m3

Fugacity: 2.12E - 7 Pa Mass fraction: 14.5% Concentration: 3.81E0 g/m3 Fugacity: 2.78E - 8 Pa Mass fraction: 85.3% Concentration: 6.23E - 1 g/m3 Fugacity: 7.85E - 8 Pa Mass fraction: 0.19% Concentration: 1.23E - 4 g/m3 0.01 kg/h

0.32 kg/h 0.58 kg/h 0.04 kg/h

110 kg/h 38.1 kg/h 899 kg/h 4.0 kg/h

33.9 kg/h 0.01 kg/h

Advection time: 208,657 h Reaction time: 14,021 h Overall persistence: 13,138 h Total emission: 1,000 kg/h Total mass: 1.31E7 kg

# Example 3: A Difficult
- to - Test Compound DTC2

16



## Physico
- chemical properties Half
- lives (hr)

• Henry's Law constant: 7.2 × 10 5 

## Pa·m3/mol

• Log Kow: 8.0

• Log Koc: 4.2



## • Log BCF: 10,000 • Air: 250

• Water: 100

• Soil: 120



## • Sediment: 9,000

Total Emission Initial Release

WWTP AIR (94.8%)

Sludge SOIL (4.7%) Effluent WATER (0.5%) 

## Emission Scenario

100%

10% 48% 90%

100% 100%

47% 5%

# Example 3: A Difficult
- to - Test Compound DTC2

17

Soil Air

Water

Sediment 776 kg/h

0.48 kg/h

0.01 R

R

R R 5 kg/h

<0.001 kg/h Fugacity: 4.18E - 6 Pa Mass fraction: 97.6% Concentration: 7.76E - 7 g/m3

Fugacity: 5.41E - 3 Pa Mass fraction: 0.70% Concentration: 1.17E - 3 g/m3 Fugacity: 1.51E - 4 Pa Mass fraction: 1.03% Concentration: 4.55E - 5 g/m3 Fugacity: 4.10E - 3 Pa Mass fraction: 0.60% Concentration: 2.39E - 6 g/m3 43.7 kg/h

1.39 kg/h 1.15 kg/h 0.002 kg/h

0.07kg/h 0.01 kg/h 4.73 kg/h 3.32 kg/h

0.05 kg/h 215 kg/h

Advection time: 102 h Reaction time: 356 h Overall persistence: 80 h Total emission: 1,000 kg/h Total mass: 7.95E4 kg

47 kg/h 948 kg/h

# Comparison of Three Test Compounds

Compound Major

compartment Major loss

mechanism Major

intermedia transport Overall

persistence (h) Easy
- to
- Test Water Degradation and advection 

## in water No significant

transport 369

DTC1 Soil,

Sediment Degradation

in soil Water to

sediment 13,138

DTC2 Air Degradation and advection in air Soil to air 80

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# Uncertainty Analysis

19 

## Input uncertainty Output uncertainty

Propagates

Probability density function

95% confidence interval X1

X2

X3 Y = 

## f (X1,X2,X3)

95% confidence interval

X1 X2 X3 Model

Contribution

Factors to the variance

# Example 3: A Difficult
- to - Test Compound DTC2

20 

## Uncertainty Analysis

Oracle Crystal Ball (v7.3.1) 

## Monte Carlo simulation 10,000 trials of random sets

# 95% Confidence Intervals and Contribution factors

21 Normalized intermedia transport rates

# Summary

• Multimedia environmental modeling like the EQC model is useful to 

# predict chemical distributions, fate processes, exposure concentrations and overall persistence.

• The inputs of the EQC model (partition coefficients, half
- lives and emission scenarios) are more easily entered with the recent update.



# • Uncertainty analysis can provide confidence intervals of model outcomes and contributing factors.

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