A EUROPEAN AEROSOL PHENOMENOLOGY: TOTAL CARBON, ELEMENTAL CARBON AND ABSORPTION COEFFICIENT Fabrizia Cavalli and JP Putaud European Commission – DG Joint Research Centre M. Zanatta Laboratory of Glaciology and Geophysics of Environment, St Martin d'Hères Cedex Paul Scherrer Institute, Laboratory of Atmospheric Chemistry, Villigen

C ARBONACEOUS AEROSOL, I. E. E LEMENTAL C ARBON AND CO - EMITTED O RGANIC COMPOUNDS, ARE RECEIVING INCREASING ATTENTION DUE TO EFFECTS ON HUMAN HEALTH AND ON GLOBAL CLIMATE DIRECTIVE 2008/50/EC ON AMBIENT AIR QUALITY AND CLEANER AIR FOR E UROPE (21 M AY 2008) CHAPTER II - SECTION 1 - Article 6 Assessment criteria In addition to the assessments referred to in paragraphs 2, 3 and 4, measurements shall be made, at RURAL BACKGROUND LOCATIONS away from significant sources of air pollution, for the purposes of providing, as a minimum, information on the total mass concentration and the chemical speciation concentrations of fine particulate matter (PM2.5) on an annual average basis … ANNEX IV MEASUREMENTS AT RURAL BACKGROUND LOCATIONS IRRESPECTIVE OF CONCENTRATION Substances - Measurement of PM2.5 must include at least the total mass concentration and concentrations of appropriate compounds to characterise its chemical composition. At least the list of chemical species given below shall be included: ▪ Major inorganic ions: SO 4 2–, Na +, NH 4 +, Ca 2+, NO 3 –, K +, Cl –, Mg 2+ ▪ O RGANIC C ARBON (OC) AND E LEMENTAL C ARBON (EC) M OTIVATION : C ONCENTRATION A BSORPTION COEFFICIENT

▪ T OTAL C ARBON, E LEMENTAL C ARBON, PM MASS, ABSORPTION COEFFICIENT in PM2.5 and in PM10 ▪ 10 EUROPEAN REGIONAL BACKGROUND SUPER-SITES, part of the EMEP measurement NETWORK ▪ 4 YEARS of data: 2008 – 2011 FINOKALIA BIRKENES VAVIHILL ASPVRETEN HARWELL MELPITZ KOSETICE PUY de DÔME ISPRA MONTSENY NORDIC CONTINENTAL HIGH ALTITUDE MEDITERRANEAN CONTENT of the STUDY:

COMMON STANDARDISED METHODOLOGY plus COMPARABILITY INFORMATION on: SAMPLING of CARBONACEOUS AEROSOLS on filters ( LEADED BY JRC ) MEASUREMENT of: T OTAL C ARBON and E LEMENTAL C ARBON CONCENTRATION ( LEADED BY JRC ) A BSORPTION COEFFICIENT RESEARCH&DEVELOPMENT and INTEGRATION ACTIVITIES for ATMOSPHERIC MEASUREMENTS within EUSAAR and ACTRIS EU-I NTEGRATED I NFRASTRUCTURES I NITIATIVES (2006 – on going) UNIQUE STUDY: HIGHLY HARMONISED DATASET AT ALL SITES

A - DEVELOPMENT of a STANDARD method and ADOPTION EUSAAR - ARTIFACT-FREE SAMPLING TRAIN Denuder efficiency from 40%-90% at different sites 1.1- DATA HARMONISATION: SAMPLING of CARBONACEOUS AEROSOLS B - TESTS to assess SAMPLING ARTIFACT across the network, in winter and summer Sampler 1 TDQ Sampler 2 TQ Sampler 3 Q Teflon filters Quartz fiber filters Front filter Denuder Sampling Head Carbon honeycomb monoliths Back-up filters - HARMONISATION CORRECTIONS for POSITIVE ARTIFACT : Maximum average correction -30% for TC no information for 3 sites - NEGATIVE ARTIFACT NOT EXACERBATED BY DENUDER : <5%

A - DEVELOPMENT of a STANDARD method and ADOPTION EUSAAR_2 protocol (C AVALLI et al., AMT 2010) for thermal-optical analysis officially adopted as standard method by EMEP 1.2- DATA HARMONISATION: ANALYSIS OF T OTAL, O RGANIC and E LEMENTAL C ARBON B - EXERCISES to assess INTER-LABORATORY COMPARABILITY within the NETWORK Five inter-laboratory comparisons - laboratory systematic BIASES and HARMONISATION FACTORS: max average deviation for EC/TC of 20% among sites using EUSAAR_2 TC and EC with protocols other than EUSAAR_2 at two sites: max average deviation on EC/TC of a factor 2.3

1.3- DATA HARMONISATION: MEASUREMENT of ABSORPTION COEFFICIENT FILTER-BASED INSTRUMENTS : MAAP: MULTI ANGLE ABSORPTION PHOTOMETER (4) PSAP: PARTICLE SOOT ABSORPTION PHOTOMETER (2) AE: AETHALOMETER (2) A - ADOPTION of STANDARDISED DATA CORRECTION PROCEDURES: MAAP: SHIFT OF THE OPERATIVE WAVELENGTH (MÜLLER et al., 2011) PSAP: CORRECTION FOR RESPONSE TO ABSORPTION AND SCATTERING (BOND et al., 1999; OGREN, 2010) AE: CORRECTION FOR MULTIPLE SCATTERING AND SHADOWING EFFECTS (WEINGARTNER et al., 2003) - ADJUSTED OF ABSORPTION COEFFICIENT TO A COMMON WAVELENGTH 637 nm with constant Absorption Ångstrom Exponent of 1 B - WORKSHOPS to assess the INTER-INSTRUMENT COMPARABILITY within the NETWORK - instrument systematic BIASES and HARMONISATION FACTORS: HF MAAP = 1 HF PSAP = HF AE = 1.6

HARMONISED ANNUAL AVERAGE of PM MASS, T OTAL C ARBON and E LEMENTAL C ARBON SIGNIFICANT POSITIVE GRADIENT from N to S 6 μgm -3 (BIR) - 30 μgm -3 (ISP) M ASS μg m -3 PM10 T OTAL C ARBON and E LEMENTAL C ARBON : SIGNIFICANT POSITIVE GRADIENT from N to S TC: 1 μgm -3 (BIR) - 10 μgm -3 (ISP) EC: 0.1 μgm -3 (BIR) - 2 μgm -3 (ISP) 2.1 a,b RESULTS: PdD high altitude site – special case! NORTHWEST SOUTH PM10 Mass:

HARMONISED ANNUAL AVERAGE of A BSORPTION COEFFICIENT 2.1 c RESULTS: A BSORPTION COEFFICIENT Mm -1 SIGNIFICANT POSITIVE GRADIENT from N to S: 0.8 Mm -1 (BIR) - 11 Mm -1 (ISP)

2.2a RESULTS: HARMONISED ANNUAL AVERAGE of T OTAL C ARBON / M ASS R ATIO L EAST CARBONACEOUS AEROSOL AT THE M EDITERRANEAN SITES, i.e. F INOKALIA and M ONTSENY : M OST CARBONACEOUS AEROSOL IN I SPRA : F OR THE MAJORITY OF THE SITES, FAIRLY HOMOGENEOUS T OTAL C ARBON / M ASS RATIO : T OTAL C ARBON / M ASS

2.2b RESULTS: HARMONISED ANNUAL AVERAGE of E LEMENTAL C ARBON / T OTAL C ARBON R ATIO F AIRLY HOMOGENEOUS (P UY DE D ÔME EXCEPTED ) E LEMENTAL C ARBON / T OTAL C ARBON RATIO : E LEMENTAL C ARBON / T OTAL C ARBON RATIO AFFECTED BY THE PROXIMITY OF EMISSION SOURCES E LEMENTAL C ARBON / T OTAL C ARBON

2.2c RESULTS: HARMONISED ANNUAL AVERAGE of A BSORPTION COEFFICIENT / E LEMENTAL C ARBON, I. E. MASS ABSORPTION CROSS SECTION m 2 g -1 MAC m 2 g -1 H OMOGENEITY IN THE MAC VALUES : 6. 6 m 2 g -1 (VHL) — 16.1 m 2 g -1 (PdD) ( P d D AND VHL HAVE A POORER DATA COVERAGE WITH LESS THAN 150 DATA POINTS ) “E UROPEAN REGIONAL BACKGROUND ” MAC = 10.8 ± 3.00

HARMONISED SEASONAL AVERAGES of T OTAL C ARBON / M ASS R ATIO WINTER SPRING SUMMER FALL WINTER SPRING SUMMER FALL PM2.5PM10 T OTAL C ARBON / M ASS 2.3a RESULTS: SEASON - SPECIFIC SOURCES OF CARBONACEOUS AEROSOL MODULATE THE SEASONAL CYCLE OF T OTAL C ARBON / M ASS RATIO

C ARBONACEOUS AEROSOL CONTRIBUTION FROM TRAFFIC CONSTANT THROUGHOUT THE YEAR M OST CARBONACEOUS AEROSOL IN WINTER - FALL DUE TO WOOD BURNING B IOGENIC AEROSOL PEAKS IN SUMMER L EAST CARBONACEOUS AEROSOL IN SPRING I NVERSE CYCLE AT FINOKALIA DUE TO AGRICULTURAL WASTE BURNING AND FOREST FIRES IN SPRING AND SUMMER FALL SUMMER WINTER TRAFFIC WOOD BURNING BIOGENIC AEROSOL SPRING 2.3a RESULTS: HARMONISED SEASONAL AVERAGES of T OTAL C ARBON / M ASS R ATIO WINTER SPRING SUMMER FALL WINTER SPRING SUMMER FALL PM2.5PM10 T OTAL C ARBON / M ASS TC / M ASS

HARMONISED SEASONAL AVERAGES of E LEMENTAL C ARBON / T OTAL C ARBON R ATIO E LEMENTAL C ARBON / T OTAL C ARBON WINTER SPRING SUMMER FALL WINTER SPRING SUMMER FALL PM2.5 PM10 E LEMENTAL C ARBON / T OTAL C ARBON RATIO SEASONAL CYCLE : MAXIMUM IN FALL - WINTER AND MINIMUM IN SUMMER 2.3b RESULTS:

2.3b RESULTS: HARMONISED SEASONAL AVERAGES of E LEMENTAL C ARBON / T OTAL C ARBON R ATIO E LEMENTAL C ARBON / T OTAL C ARBON WINTER SPRING SUMMER FALL WINTER SPRING SUMMER FALL PM2.5 PM10 R EMARKS : -L ESS PRONOUNCED CYCLE AT CONTINENTAL SITES DUE TO WEAKER BIOGENIC SOURCES / OR STRONGER TRAFFIC SOURCE - AT F INOKALIA : MAXIMA IN SPRING - SUMMER DUE TO FIRES - AT P UY DE D ÔME : CYCLE DETERMINED MAINLY BY THE BOUNDARY LAYER DYNAMIC FALL SUMMER WINTER WOOD BURNING BIOGENIC AEROSOL SPRING TRAFFIC EC / TC

HARMONISED SEASONAL AVERAGES of A BSORPTION COEFFICIENT / E LEMENTAL C ARBON, I. E. MASS ABSORPTION CROSS SECTION WINTER SPRING SUMMER FALL MAC m 2 g -1 M AC SEASONAL CYCLE : - MAXIMUM IN SUMMER AT THE MAJORITY OF SITES - I N CORRESPONDENCE TO THE MINIMUM OF THE EC / TC RATIO ( I. E. MAXIMUM ABUNDANCE OF ORGANIC CARBON ) - T HIS WOULD INDICATE AN AMPLIFICATION OF EC ABSORPTIVITY BY THE THICKER O RGANIC C ARBON COATING 2.3c RESULTS:

3. CONCLUSIONS P HENOMENOLOGICAL H IGHLY INTEGRATED NETWORK AND A BIAS - FREE DATASET ALLOW UNDERSTANDING SOURCES AND TRANSFORMATION OF AEROSOLS O N A E UROPEAN REGIONAL BACKGROUND SCALE : -C LEAR POSITIVE SPATIAL GRADIENT – FROM N TO S – FOR ALL EXTENSIVE AEROSOL PROPERTIES : PM MASS, T OTAL C ARBON & ELEMENTAL C ARBON AND ABSORPTION COEFFICIENT - HOMOGENEITY FOR ALL INTENSIVE AEROSOL PROPERTIES : T OTAL C ARBON / M ASS, E LEMENTAL C ARBON / T OTAL C ARBON AND MAC -S EASONALITY OF INTENSIVE AEROSOL PROPERTIES AND SOURCES : -T OTAL C ARBON / M ASS : M AXIMA IN FALL - WINTER ( WOOD BURNING ) AND IN SUMMER ( BIOGENIC AEROSOL ) -E LEMENTAL C ARBON / T OTAL C ARBON : M AXIMUM IN FALL - WINTER AND MINIMUM IN SUMMER -A BSORPTION COEFFICIENT / E LEMENTAL C ARBON : M INIMUM IN FALL - WINTER AND M AXIMUM IN S UMMER S CIENTIFIC PUBLICATION (C AVALLI ET AL., in preparation ) M ETHODOLOGICAL : -I MPORTANCE OF COMMON STANDARDISED PROCEDURES FROM SAMPLING TO DATA SUBMISSION -T HIS IS A MORE EFFICIENT AND ACCURATE APPROACH THAN APPLYING a-posteriori CORRECTION FACTORS -P ERIODICAL CHECKS OF COMPARABILITY I NTERNATIONAL P ROGRAMMES ( EMEP AND AQUILA ) E UROPEAN T ECHNICAL B ODY FOR STANDARDS – CEN WG 35 – IN SUPPORT TO EU-DIR IMPLEMENTATION I NTERNATIONAL OBSERVATIONS - MODELS COMPARISON INITIATIVES - A ERO C OM J RC EXPERTISE P ROJECT PRODUCTS P ILOT EXPERIMENT