Modelling Persistent Organic Pollutants (POPs) with GEOS-CHEM

Jordi Dachs1,2, Noelle Eckley2, Daniel Jacob2

1Department of Environmental Chemistry, Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain.

2Harvard Atmospheric Chemistry Modelling Group,Harvard University, Cambridge, MA, USA.

Persistent Organic Pollutants (POPs)

POPs are a wide range of organic compounds that:

- are extremely stable and persistent in the environment.

- Bioaccumulate in organisms and food chains.

- Have potential for long range transport.

- Toxic

Polychlorinated Biphenyls (PCBs)

Cln Clm

- Used in capacitors and transformers. Other uses in paints, plasticizers, etc.

- Carcinogens. Neurological, reproductive and immune effects.

The Dirty Dozen

•Aldrin - 1949 - Insecticide used against soil pests (primarily termites) on corn, cotton and potatoes.•Chlordane - 1945 - Insecticide now used primarily for termite control.•DDT - 1942 - Insecticide now used mainly against mosquitoes for malaria control.•Dieldrin - 1948 - Insecticide used on fruit, soil and seed crops, including corn, cotton and potatoes.•Endrin - 1951 - Rodenticide and insecticide used on cotton, rice and corn.•Heptachlor - 1948 - Insecticide used against soil insects, especially termites. Also used against fire ants and mosquitoes.•Hexachlorobenzene - 1945 - Fungicide. Also a by-product of pesticide manufacturing and a contaminant of other pesticide products.•Mirex - 1959 - Insecticide used on ants and termites. One of the most stable and persistent pesticides. Also a fire retardant.•Toxaphene - 1948 - Insecticide used especially against ticks and mites. A mixture of up to 670 chemicals.•PCBs - 1929 - Used primarily in capacitors and transformers, and in hydraulic and heat transfer systems. Also used in weatherproofing, carbonless copy paper, paint, adhesives and plasticizers in synthetic resins.•Dioxins - 1920s - By-products of combustion (especially of plastics) and of chlorine product manufacturing and chlorine bleaching of paper.•Furans - 1920s - By-products, especially of PCB manufacturing, often with dioxins

Stockholm Convention on Persistent Organic Pollutants

Objectives

- To develope a GEOS-CHEM module forPOP modelling with aims to:

- Determine the POP potential for long range transport.

- Constrain the atmospheric and oceanic sinks of POPs.

- To elucidate the relative importance of primary and secondary sources.

- Support regional field studies

Persistent Organic Pollutants (POPs)Physical Chemical Properties

Vapor Pressure

(Schwarzenbach et al. Environmental Organic Chemistry 1999)

Multimedia Partitioning of POPs

CG

CWCP

CAAir-WaterExchange

Water-Particle Partitioning

Gas-Particle Partitioning

Dry Deposition

Wet Deposition

Vertical Fluxes

Advection

Bioaccumulation

Continental Inputs

Atmospheric Transport

Degradation

Environmental fate of organic pollutants

Major Permanent sinks:

- Ocean interior (sediments, deep waters)

- Atmospheric OH degradation

Comparison of the Atmospheric and Oceanic Sinks of PCBs

0

50

100

150

200

250

28 52 101

153

180

Glo

bal

atm

osp

her

ic s

inks

ove

r th

e o

cean

(tn

y-1

)

Oceanic Sink

Reaction with OH radical

The atmospheric and Oceanic sinks account for about 2% of historical emissions (as estimated by Breivik et al. Sci. Total Environ. 2002)

Potential Environmental Reservoirs of POPs

(Dalla valle, M., Dachs, J., Sweetman, A.J., Jones, K.C. Global Biogeochem. Cycles 2004.

Dalla valle, M., Jurado, E., Dachs, J., Sweetman, A.J., Jones, K.C. Environ. Pollut. 2005.)

180ºW 135ºW 90ºW 45ºW 0º 45ºE 90ºE 135ºE 180ºE

90ºN

60ºN

30ºN

0º

30ºS

60ºS

90ºS

0 20 40 60 80 100 120 140 160 180 200

Inventory in soil or ocean mixed layer / Inventory in atm boundary layer

PCB 101

0

20000

40000

60000

80000

100000

120000 -9

0-6

0-3

00

30

60

90

La

titu

de

Soil conc (pg/g dry wt)020000

40000

60000

80000

100000

120000

Total PCB usage (tonnes)

Soil Conc (pg g-1)

PCB usage (tn)

Modifications/additions to GEOS CHEM.

1 – Primary Emissions

2 – Soil/Vegetation reservoirs

3 – Oceanic researvoir and sink

3 - Atmospheric processes

Modifications to GEOS CHEM. 1. Emissions

PCB Consumption and Emissions (Spatially and temporally resolved)

0

5000

10000

15000

20000

25000

30000

35000

1930

1934

1938

1942

1946

1950

1954

1958

1962

1966

1970

1974

1978

1982

1986

1990

1994

1998

Year

PC

B C

on

sum

pti

on

(tn

)

(Knut Breivik, NILU)

Modifications to GEOS CHEM. 2. Soil-Vegetation Reservoirs

fOC

- All partitioning processes driven by fugacity gradients (air-soil, air-vegetation).- Use of spatial resolved data sets for soil OC, vegetation biomass, ....

Soil OC

Vegetation uptake of POPs

MRC(Dalla valle, M. et al. Global Biogeochem. Cycles 2004.)

(Wania & Mclachlan ES&T, 2001.)

Air-Water-Phytoplankton Exchange of POPs

Air-water exchange

Water-phytoplankton exchange

CA

MLD CW CP

FWP

FAW

W

AAWAW C

HC

kF'

Pu

GdWWPWP C

kkk

CkF

-J. Dachs, S.J. Eisenreich, J.E. Baker, F.C. Ko, J.D. Jeremiason. Environ. Sci. Technol. 33, 3653-3660, 1999.

Vertical Flux

P

u

GdSinkSink C

kkk

kF

FSink

>> cruise data>> cruise data

RRS Bransfield Oct-Dec 1998, Rainer Lohmann PCDD/Fs

RV PELAGIA Jan-Feb 2001Foday Jaward PCBs

GAS: Cg

[fg m-3]0 10 20 30 40 50 60

90ºN

60ºN

30ºN

0º

30ºS

60ºS

90ºS

AEROSOL: Cp

[fg m-3]0 10 20 30 40

90ºN

60ºN

30ºN

0º

30ºS

60ºS

90ºS

(Lohmann et al. EST 2001, Jaward et al. EST 2004)

ClCl55DD atmospheric concentration DD atmospheric concentration

0

0.4

0.8

1.2

1.6

2

22 52 95 99 110 187 174

FS

ink

(ng

m-2

d-1

)

Measured

Predicted

0

2

4

6

8

10

28 52 44 70 101 118 153 138 187 180 170

FS

ink

(ng

m-2

d-1

)

MeasuredPredicted

0

1

2

3

4

28 52 101 118 153 138 180

FS

ink

(ng

m-2

d-1

)

Measured

Predicted

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

180 360 540 720

60

120

180

240

300

360

180W 90W 0 90E 180E

90N

60N

30N

0

30S

60S

90S

ng m-2 d-1

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

180 360 540 720

60

120

180

240

300

360

180W 90W 0 90E 180E

90N

60N

30N

0

30S

60S

90S

ng m-2 d-1

PCB 180

Comparison of Measured and Predicted PCB Sinking FluxesNorth Atlantic Ocean

(Gustafsson et al 1997)

Mediterranean Sea

(Dachs et al 1996)

Arabian Sea

(Dachs et al 1999)

(Dachs et al. Environ Sci. Technol, 2002)

Modifications to GEOS CHEM. 3. Ocean Reservoir and Sink

CA

CWCP

CAPAir-WaterExchange

Dry AerosolDeposition

Wet DepositionDry Aerosol

Deposition

Wet Deposition

ML

D

Sinking Fluxes

- All partitioning processes driven by fugacity gradients (air-water, water-phytoplankton, ...).- Use of climatologies of chl, MLD, SST.

Modifications to GEOS CHEM. 4. Atmospheric Processes

- Degradation with OH ( Anderson and Hites 1996).

- Dynamic gas-particle partitioning from aerosol organic and elemental carbon.

SAECOAOMOMOCT

OCTOCTOMP KfK

MWMW

fK 1212 101

10

-5

-4

-3

-2

-1

0

1

-5 -4 -3 -2 -1 0 1

Predicted log KP (from m 3 g-1)

Me

asu

red

lo

g K

P (f

rom

m3

g-1

)

Slope=1.01+0.01

r2=95.1p<0.001

Chesapeake Bay

-5

-4

-3

-2

-1

0

1

-5 -4 -3 -2 -1 0 1

Predicted log KP (from m3 g-1)

Mea

sure

d l

og

KP

(fr

om

m3

g-1

)

Phenanthrene PyreneFluoranthene Chrysene

Slope=0.99+0.01

r2=89.3p<0.001

Baltimore

(Dachs & Eisenreich, ES&T 2000

Jurado et al. ES&T 2004)