A multi-compartment modeling system for
estimating emissions and transport of
persistent organic pollutants
The case of benzo(a)pyrene
Presented at the 13th Annual CMAS conference
11/27/14 • Chapel Hill, NC
by
Christos Efstathiou, Jana Matejovicova, Martin Tomas, Tom Rebok, Gerhard Lammel
Research Center for Toxic Compounds in the Environment
Centrum pro výzkum toxických látek v prostředí
Kamenice 753/5, pavilon A29, 625 00 Brno, Czech Republic
Outline
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Introduction
Setting up the models
Adaptations to treat POPs
Model results
Summary and future aims
13th Annual CMAS conference, Chapel Hill, North Carolina
RECETOX Modeling Group - 2
Rationale: POPs & Environment
• POPs have been an active topic of environmental chemistry and
toxicology since the 1960s
• Several POPs including PCBs and agrochemicals banned – still observed!
• Different intrinsic physical-chemical properties dictate environmental fate
Single-hoppers, Multi-hoppers, swimmers, flyers - Persistent in various
environmental compartments (e.g. soil, vegetation) – LRT a concern
• Significant adverse effects at low doses
• Highly bioaccumulative
Object of the Stockholm Convention and the Aarhus Protocol (UNECE, 98)
BaP target values for air concentrations – national policymaking
EU: 1 ng/m3 (annual average) - UK: 0.25 ng/m3
Benzo(a)pyrene has received attention as a representative toxic substance
for PAHs with substantial experimental and modeling efforts
13th Annual CMAS conference, Chapel Hill, North Carolina
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Research Objectives
Enhance CMAQ to account for emission and transport of POPs between
environmental compartments
Which POPs ?
•BaP (PAH)
•PCBs (representative congeners)
•DDT (insecticide)
Study specifics
•Seasonal and inter-annual variation of the concentration and depositions
•Implement and evaluate relevant Gas – Particle Partitioning (GPP) and
heterogeneous chemistry schemes
•Include soil-atmosphere exchange scheme – additional soil compartment
13th Annual CMAS conference, Chapel Hill, North Carolina
RECETOX Modeling Group - 4
Research Objectives
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Model Setup
physical schemes and parameterisations
Weather Research Forecast (WRF) Model version 3.2.1
• GFS inputs (spatial resolution 0.5° x 0.5°)
• Long wave radiation scheme `RRTM`
• Short wave radiation scheme `Dudhia`
• Near-surface `Monin-Obukhov` scheme
• `WSM` 3-class simple ice scheme
• Land-surface scheme `Noah` with 4 soil layers
Community Multiscale Air Quality (CMAQ) Model version 4.7.1
• Carbon Bond 5 (CB-5) chemistry scheme incl. aqueous chemistry
• 4th Generation aerosol module (AERO4)
• Emissions from SMOKE-EU model (Biogenic + Anthropogenic + BaP)
Bieser, J., Aulinger, A., Matthias, V., Quante, M., & Builtjes, P. (2011). SMOKE for Europe –
adaptation, modification and evaluation of a comprehensive emission model for Europe.
Geosci Model Dev, 4(1), 47–68. doi:10.5194/gmd-4-47-2011
13th Annual CMAS conference, Chapel Hill, North Carolina
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B(a)P Emissions – major sources
PAHs are formed by any incomplete combustion of organic matter
• Incineration of household and medical waste
• Iron and steel production
• Electricity generation
• Residential heating
• Road transport
• Ship engines
• Oil platforms
• Wildfires
Emission Inventories for
legacy POPs and agrochemicals are limited
(Breivik et al., 2002)
13th Annual CMAS conference, Chapel Hill, North Carolina
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CMAQ modifications for POPs
Emissions mapping to different aerosol modes (99% into accumulation)
IC & BC were obtained from global model (Stemmler & Lammel, ‘12)
Gas-phase chemistry
•Reaction with ozone for BaP
•Reaction with OH for PCBs
General considerations and implicit assumptions for GPP schemes:
•Instantaneous relaxation to phase equilibrium
•Compound does not irreversibly reacting in particulate phase
•Sorption processes do not interact
13th Annual CMAS conference, Chapel Hill, North Carolina
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Gas-Particle Partitioning schemes
• J-P adsorption model (Junge ‘77 – Pankow ‘87)
• Dissolution to aerosol water (Aulinger et al., ‘07, Cooter & Hutzell ‘02)
• Absorption to organic matter (OM – Harner & Bidleman ’98)
• Absorption to elemental carbon (EC – Dachs & Eisenreich ‘00)
Developed CMAQ Fortran modules
• Set the partitioning scheme(s) configuration
• Calculate the physico-chemical parameters of POPs
• Solve the system of equations for the selected GPP(s)
Heterogeneous chemistry
• Reaction with O3 (Langmuir-Hinshelwood mech., Kwamena et al., ‘04)
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Soil-atmosphere exchange module
Soil-Atmosphere exchange module according to Jury
0
- mt
soil
Fvol = C e
DE
pt
æ
ç 1- e
è
L2
4 Dgt
ö
÷
ø
Linked to :
•Initial soil burden from global model output (Stemmler & Lammel, ‘12)
•WRF output (driver variables soil Temperature, moisture)
•European Soil Database (key soil parameters, including OC fraction) +
Harmonized World Soil Database (gap filling)
•Depositions from CMAQ output
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Annual means and spatial distribution of the effect of GPP
schemes
J-P
annual
mean
J-P_W /
J-P_W_KOA
13th Annual CMAS conference, Chapel Hill, North Carolina
J-P /
J-P_W
(=+ Water
dissol.)
J-P_W_KOA /
J-P_W_KOA_EC
(= +
Dual Model
KOA+EC)
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Comparison against measurements: GENASIS database
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Comparison against Active and passive samples: Kosetice
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Comparison against GENASIS database
1119 observation – modeled pairs
Measurement J-P only
Median 0.022130
0.004420
Mean
0.085950
0.005175
Std. dev 0.343190
0.003519
R2
0.980519
13th Annual CMAS conference, Chapel Hill, North Carolina
JP_W
JP_W_KOA
0.004398 0.007350
0.005513 0.009197
0.004130 0.006825
0.979035 0.928591
JP_W_DL
0.007527
0.009389
0.006935
0.925308
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Size distribution
Brno, 2006
Kosetice, 2006
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Concentrations of BaP
Jan 17 -18
17
.1
0
17 :00
.1
2
17 :00
.1
17 4:0
.1 0
6
17 :00
.1
17 8:0
.1
0
1
17 0 :0
.1
0
1
17 2 :0
.1
0
1
17 4 :0
.1
0
1
17 6 :0
.1
0
1
17 8 :0
.1
0
2
17 0 :0
.1
0
22
18 :00
.1
0
18 :00
.1
2
18 :00
.1
18 4:0
.1 0
6
18 :00
.1
18 8:0
.1
0
1
18 0 :0
.1
0
1
18 2 :0
.1
0
1
18 4 :0
.1
0
1
18 6 :0
.1
0
1
18 8 :0
.1
0
2
18 0 :0
.1
0
22
:0
0
nanograms/m3
CMAQ model output – wet deposition
Wet deposition
Jan 17-18
g/ha/h
0,45
0,4
0,35
0,3
0,25
0,2
0,15
0,1
0,05
0
Aspvreten
13th Annual CMAS conference, Chapel Hill, North Carolina
Kosetice
Rucava
Zoseni
RECETOX Modeling Group - 16
Summary
• Simulations showed good correlations to measurements, improving
with more complex GPP schemes
• Simulations underestimate measurements – further analysis needed to
evaluate usefulness of PUF samplers
• Emissions seem to be missing a background winter component –
possibly domestic heating?
• Evaluate the new compartment with more volatile POPs (PCBs) –
include soil degradation, effects of vegetation
• Develop data assimilation methods to incorporate information of initial
soil burdens
• Evaluate different heterogeneous reactions (Perraudin et al., ‘07)
• Evaluate the effect of different meteorological inputs and land surface
models (LSM) on the soil-atmosphere exchange module
13th Annual CMAS conference, Chapel Hill, North Carolina
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Thank you!
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