Modelling atmospheric transport of Benzo(a)Pyrene with CMAQ The need for time resolved emissions V. Matthias, A. Aulinger GKSS Research Centre, Geesthacht, Germany

Research Objectives Investigation and assessment of air pollution , i.e. persistent organic pollutants (POPs) in Europe Deposition of POPs into the North and Baltic Sea Focus on coastal regions Evaluation of past and forecast of future developments (scenarios) on time scales of decades Assessment of the impact of regulations

CMAQ model domain and nest 54x54 km2 grid 18x18 km2 grid 30 vertical layers

BaP was included as a new substance into CMAQ is mainly particle bound we consider 3 particle modes and the gas phase model results can be compared to (few) measurements

Meteorology, initial and boundary conditions Meteorological fields are calculated with MM5 Boundary Layer: MRF (Hong and Pan, 1996) Microphysics: Reisner 2, incl. ice, snow and graupel (Reisner et al., 1998). Cumulus: Kain Fritsch 2, (Kain and Fritsch, 1993) One year is represented by four months (January, April, July and October), selected years will be calculated (starting with 2001) Interest in long term runs / use of met. fields from other models (e.g. CLM) ICs: constant profiles, one day spinoff time for each month BCs: Either constant profiles or daily means from a global CTM (MOZART)

Emissions Hourly anthropogenic emissions of 2000 for CO, NOx, SO2 , NH3 , NMVOC (in RADM speciation), PM2.5 and PM10 on the 54 km and 18 km CMAQ grid provided by the IER Stuttgart. Biogenic emissions of terpenes and isoprene from POET database (monthly values for 2000 on 1° x 1°), addition of a diurnal cycle for isoprene, no diurnal cycle for terpenes Sea salt emissions internally considered by CMAQ (depending on wind speed)

BaP Emissions Available data: Annual BaP emissions for 1970, 1975, 1980, 1985, 1990, 1993/1995, provided by Dr. Knut Breivik on the 50 x 50 km² polar stereographic EMEP grid. Annual BaP emissions (in 5 sectors) based on TNO report for 2000 also on the EMEP grid but: no temporal resolution available Main sources are residential heating traffic industry (steel and coke) Annual, weekly and diurnal cycles need to be considered

Temporal cycle of BaP Emissions season Residential heating: depends on season Traffic: depends on working times Industrial emissions: depend on working days week day

Example BaP Emissions (1) Based on 1993/1995 annual emissions

Example BaP Emissions (2) Based on 2000 annual emissions

Model Results (1) Jan /July 2001 based on 1995 emissions

Model Results (2) Monthly concentrationmeans of 2001 based on 1995 emissions in North Sea areas

Wet deposition 1995 vs 2000 emissions

Comparison to measurements - January blue: 1995 emissions red: 2000 emissions black: measurements (monthly means)

Comparison to measurements - July blue: 1995 emissions black: measurements (monthly means)

Summary and Outlook First results of BaP simulations with CMAQ look promising BaP emissions need improvement ( incl. ship emissions) Reconstruction of BaP concentrations 1970 –2000 based on EMEP emissions Include other POPs (eg. PAHs, PCBs, PFOS) Include second nest simulations

Partitioning

Measured size distributions

Simulated particulate BaP concentrations Aspvreten Kosetice

Simulations vs. ground measurements Measured mean Model mean

Simulations vs. ground measurements Model mean Measured mean

Simulated particulate BaP concentrations in September 2001 Bornhöved Zingst

Simulations vs. ground measurements

Simulations vs. ground measurements

CMAQ in a ´very small´ domain Run CMAQ on a 1x 1 grid to investigate processes Example: BaP wet deposition under predefined conditions:

Nitrogen deposition into the North Sea

Nitrogen deposition into the North Sea: influence of meteorological fields control run / shallow convection run

Adsorption to dry surface Φad adsorbed fraction of compound c Junge parameter θ surface of adsorbat pL subcooled liquid vapor pressure

Absorption into organic matter Φab absorbed fraction of compound Kp gas/particle partitioning constant Kp octanol/air partitioning constant fOC fraction of organic carbon TSP total suspended particles mass

Absorption into aerosol water Φaq absorbed fraction of compound Kp gas/particle partitioning constant Kp water/air partitioning constant fOC fraction of aerosol water TSP total suspended particles mass

Simulated gaseous BaP concentrations in September 2001

Total simulated BaP depositions in September 2001

Interest in long term runs / use of met. fields from other models Meteorology Meteorological fields are calculated with MM5 Boundary Layer: MRF (Hong and Pan, 1996), based on Troen and Mahrt (1986) nonlocal diffusion concept. Microphysics: Reisner 2, incl. ice, snow and graupel (Reisner et al., 1998). Cumulus: Kain Fritsch 2, conservation of mass, thermal energy, total moisture and momentum (Kain and Fritsch, 1993) Interest in long term runs / use of met. fields from other models

Processes BaP is emitted as accumulation mode aerosol (with 0.1% in Aitken-mode) Gas-particle partitioning considering three aerosol modes (Junge-Pankow concept) Dry deposition, scavenging and wet deposition as for aerosol particles in CMAQ No photolytical and chemical degradation so far