Modelling Persistent Organic Pollutants (POPs) with GEOS-CHEM Jordi Dachs 1,2, Noelle Eckley 2, Daniel Jacob 2 1 Department of Environmental Chemistry, Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain. 2 Harvard 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) Cl n Cl m - Used in capacitors and transformers. Other uses in paints, plasticizers, etc. - Carcinogens. Neurological, reproductive and immune effects.

The Dirty Dozen Aldrin Insecticide used against soil pests (primarily termites) on corn, cotton and potatoes. Chlordane Insecticide now used primarily for termite control. DDT Insecticide now used mainly against mosquitoes for malaria control. Dieldrin Insecticide used on fruit, soil and seed crops, including corn, cotton and potatoes. Endrin Rodenticide and insecticide used on cotton, rice and corn. Heptachlor Insecticide used against soil insects, especially termites. Also used against fire ants and mosquitoes. Hexachlorobenzene Fungicide. Also a by-product of pesticide manufacturing and a contaminant of other pesticide products. Mirex Insecticide used on ants and termites. One of the most stable and persistent pesticides. Also a fire retardant. Toxaphene Insecticide used especially against ticks and mites. A mixture of up to 670 chemicals. PCBs 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 s - By-products of combustion (especially of plastics) and of chlorine product manufacturing and chlorine bleaching of paper. Furans s - 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

CGCG CWCW CPCP CACA Air-Water Exchange 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 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 Dalla valle, M., Jurado, E., Dachs, J., Sweetman, A.J., Jones, K.C. Environ. Pollut ) Inventory in soil or ocean mixed layer / Inventory in atm boundary layer PCB 101 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) (Knut Breivik, NILU)

Modifications to GEOS CHEM. 2. Soil-Vegetation Reservoirs fOCfOC - 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 CACA MLD CWCW CPCP F WP F AW -J. Dachs, S.J. Eisenreich, J.E. Baker, F.C. Ko, J.D. Jeremiason. Environ. Sci. Technol. 33, , Vertical Flux F Sink

>> cruise data RRS Bransfield Oct-Dec 1998, Rainer Lohmann PCDD/Fs RV PELAGIA Jan-Feb 2001 Foday Jaward PCBs GAS: C g [fg m -3 ] AEROSOL: C p [fg m -3 ] (Lohmann et al. EST 2001, Jaward et al. EST 2004) Cl 5 DD atmospheric concentration

PCB 180 Comparison of Measured and Predicted PCB Sinking Fluxes North 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 - 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. (Dachs & Eisenreich, ES&T 2000 Jurado et al. ES&T 2004)