Perriono Helsinki TFMM

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PM10 and PM2.5 MASS CLOSURE in the LAZIO region (CENTRAL ITALY) Cinzia PERRINO C.N.R. Institute of Atmospheric Pollution Montelibretti (Rome) A study funded by the Lazio region EMEP TFMM 7th MEETING – HELSINKI, 10th-12th May 2006

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ROME – TRAFFIC STATION : 194 PM10 EXCEEDANCES IN 2004 OUR STARTING POINT

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WHICH CONDITIONS LEAD TO EXCEEDANCES? WHICH COMPOUNDS ARE RESPONSABLE FOR THE INCREASE IN PM CONCENTRATION? WHICH SOURCES ARE RESPONSABLE FOR THE DIRECT OR INDIRECT PRODUCTION OF THESE COMPOUNDS? WHICH ARE THE DRIVING FACTORS DETERMINING THE TIME PATTERN OF ATMOSPHERIC POLLUTANTS?

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“Fine Dust” 2004 - 2005 A research project funded by the Lazio Region

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C. PERRINO - C.N.R. Institute of Atmospheric Pollution October 2004 – July 2005 (daily sampling – analysis of the 140 most interesting days) Six stations: 1 regional background, 1 urban background, 1 peri-urban, three urban stations (Roma, Latina Viterbo) Two size fractions: PM10, PM2.5 Study of the chemical composition of atmospheric particles apportionment of particle sources discrimination between natural and anthropogenic events

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3-step procedure: Mixing properties of the lower atmosphere Size distribution of particulate matter Chemical composition of particles Natural radioactivity monitoring Optical particle counter Analysis of metals, ions, carbon compounds

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Having information about the air volume available for pollution dispersion we could uncouple pollutants variations due to changes in the emission rate from those due to changes in the dilution properties of the atmosphere

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Weak mixing of the lower atmosphere: Radon is trapped in the lower layer and its air concentration increases Convective mixing of the lower atmosphere: Radon dilutes into the whole mixing layer

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ATMOSFERIC STABILITY MONITOR the instrument collects atmospheric particles and determines the natural radioactivity due to Radon progeny (1-h average). identification of stability periods and advection periods good index of the dilution properties of the lower atmosphere

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During cold months high-pressure periods are sporadic and advection often occurs. Diurnal mixing is weak and of limited duration. During warm months natural radioactivity shows a well-defined and modulated temporal pattern (all days are similar: nocturnal stability and convective mixing during the day)

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JUNE – JULY 2003 DECEMBER 2003 NATURAL RADIOACTIVITY NATURAL RADIOACTIVITY

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STEP 1: Mixing properties of the lower atmosphere

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STEP 1: Mixing properties of the lower atmosphere

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Starting from natural raadioactivity values we can develop Atmospheric Stability Indexes… … for each day, they give the probability, from the meteorological point of view, for the occurrence of an atmospheric pollution event STEP 1: Mixing properties of the lower atmosphere EXPERIMENTAL FORECASTED

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The episode of December 27th 2003 in Rome: traffic or meteorology?

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The mixing properties of the lower atmosphere are a key factor in determining PM concentration level and its time variations FIRST REMARK

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3-step procedure: Mixing properties of the lower atmosphere Size distribution of particulate matter Chemical composition of particles Natural radioactivity monitoring Optical particle counter Analysis of metals, ions, carbon compounds

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Optical particle counter in six size ranges: 0.3 – 0.5 m; 0,5 – 1,0 m; 1,0 – 1,5 m; 1,5 – 2,0 m 2 – 5 m; 5 – 10 m

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Evaluation of the ratio between the number of particles in the coarse ( > 1,5 m) and the fine (0,3 – 0,5 m) ranges

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Daily average ratio between the number of particles in the coarse ( > 1,5 m) and the fine (0,3 – 0,5 m) ranges

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FASE 2: DISTRIBUZIONE DIMENSIONALE DELLE PARTICELLE In the case of natural events (e.g. Saharan dust intrusions) the Atmospheric Stability Indexes are much lower than the real concentration of PM

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3-step procedure: Mixing properties of the lower atmosphere Size distribution of particulate matter Chemical composition of particles Natural radioactivity monitoring Optical particle counter Analysis of metals, ions, carbon compounds

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Chemical characterisation: 1.  Anions and cations (NO3-, SO4=, Cl-, Na+, Ca++, Mg++, K+, NH4+)  2. Elemental carbon and organic carbon compounds (EC, OC) 3.  Crustal metals (major components) (Si, Al, Fe, Ca, K) 4. Inorganic volatile components (ammnium chloride and nitrate)

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Organic carbon Elemental carbon PM10 PM2.5 Termo-optical analyser ED-XRF Extraction ICP Ion chromatography Trace metals Anions and cations Univ.of Rome “La Sapienza” Chemistry Department plus DIFFUSION LINES at ML station

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MASS CONCENTRATION OF PM10 IN MONTELIBRETTI (ROME) MEASURED BY THE DUST MONITOR (blue) AND RECONSTRUCTED BY THE CHEMICAL ANALYSES (red)

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MASS CONCENTRATION OF PM2.5 IN MONTELIBRETTI (ROME) MEASURED BY THE DUST MONITOR (blue) AND RECONSTRUCTED BY THE CHEMICAL ANALYSES (red)

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10-15% of the ammonium nitrate is lost by the 20°C monitor and about 80% is lost by the 45°C monitor

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[sea-spray aerosol] = (Na+ + Cl-) * 1.176 [SO4= Mg Ca K] [crustal] = (1.89 Al + 2.14 Si + 1.4 Ca + 1.2 K + 1.36 Fe) * 1.12 [Mg Na Ti] [primary anthropogenic compounds] = EC * 2 [OM] [secondary compounds] = NH4+ + SO4= + NO3- + (OM – EC) 4 main sources

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Sea-spray events: NaCl concentration increases from 1-2% to 20-40% the coarse/fine ratio increases they occur in advection conditions (generally clean air masses) PM10 concentretion is low; the increase due to sea-salt is generally < 10 ug/m3 generally they do no cause exceedances they have low impact on PM2.5 concentration

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Saharan dust events: crustal matter concentration increases from 10-20% to over 50% the coarse/fine ratio increases they begin in advection conditions (but re-suspension may increase the time duration of the episode) PM10 concentretion can be very high (up to more than 100 ug/m3) they often cause exceedances they also generally cause an increase of PM2.5 concentration

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IDENTIFICATION AND CHARACTERISATION OF NATURAL EVENTS:

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Natural events can be identified from an increase of the coarse-to-fine ratio and are characterised by advection conditions SECOND REMARK

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ELEMENTAL CARBON PRIMARY ANTHROPOGENIC POLLUTANTS

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Average % composition of PM10 in the Lazio region

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Average % composition of PM2.5 in the Lazio region

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For primary anthropogenic pollutants we cannot identify “events” Their concentration depends on the proximity to the emission sources and their concentration variations mainly depend on the dispersion capacity of the lower atmosphere THIRD REMARK

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SULPHATE SECONDARY POLLUTANTS

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Average % composition of PM10 in the Lazio region

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Average % composition of PM2.5 in the Lazio region

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PM10 Secondary pollutants are homogeneously distributed at least on a regional scale.

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PM10 PM10-2.5 PM2.5

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For secondary pollutants we cannot identify “events” Their concentration is homogeneous on a regional scale and their concentration variations mainly depend on the dispersion capacity of the lower atmosphere FOURTH REMARK

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PM10 concentration higher than 65 mg/m3 PM composition during polluted days is very close to PM composition during clean days with the exception of days characterised by important natural events

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FASE 3: COMPOSIZIONE CHIMICA DEL MATERIALE PARTICELLARE PM10 - 2.5 SIA L’AEROSOL MARINO CHE LE SPECIE DI DERIVAZIONE TERRIGENA SONO UNA COMPONENTE QUANTITATIVAMENTE IMPORTANTE DELLA FRAZIONE COARSE