The efect of diesel Sulfur content on PM2.5 aburra valley colombia

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This paper was presented at the Air Pollution conference in Athens in 2012. Describes research done at the Aburra Valley during the change in sulfur content of the diesel fuel

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The efect of diesel Sulfur content on PM2.5 aburra valley colombia

  1. 1. THE EFECT OF THE DIESEL FUEL SULPHUR CONTENT ON THE PM2.5 POLLUTION PROBLEM IN THE ABURRÁ VALLEY REGION AROUND MEDELLÍN, COLOMBIA E. Posada (1), M. Gómez (2) (1) INDISA S.A ,Carrera 75 # 48 A 27, Medellín, Colombia (2) Politécnico Colombiano, Medellín, Colombia Presenting author email: enrique.posada@indisa.com co-author mgomez@elpoli.edu.coABSTRACTThe Aburrá Valley region has 3.5 million people, including the city of Medellín. Diesel fuel went down from 2,100 ppmto 500 ppm and then to 50 ppm, between the end of 2009 and the first six months of 2010. A study was made todetermine the impact on the PM2.5 environmental concentrations and on the chemical composition of the PM2.5 matter.This was done by taking PM2.5 samples in several sites and doing chemical analysis on the samples, which includedmetals, anions and cations and carbonaceous matter (EC and OC). The study included samplings in a vehicle tunnelserving the city and emission sampling in a laboratory diesel fuel motor. A clear link was established between dieselsulphur content and PM2.5 compositions and concentrations, which indicates the large influence of diesel fuel vehiclesimpact on the pollution situation in the region and the importance of this sulphur diminution.1. INTRODUCTIONThe Aburrá Valley region in the Andean range of Colombia, has 3.5 million people, with the city of Medellínat its centre. It is a region surrounded by high mountains with relatively poor ventilation. Under the pressureof the environmental authorities, the national provider of diesel fuel decided to supply to the region lowsulphur diesel, to contribute to the lowering of the PM2.5 concentrations in the air. S contents went down from2,100 ppm to 500 ppm and then to 50 ppm between the end of 2009 and the first six months of 2010. Thischange came after a long period of time in which most of the emphasis of the air pollution problem was laidupon industrial sources. Despite the programs developed for industrial control, not much favourable changewas noticed in the urban PM concentrations, so finally the authorities began attacking the problem of mobilesources pollution, which has been steadily growing with the increase in population and traffic. Although theregion counts with a metropolitan metro train and innovative cable mass transportation systems, there are stilllarge amounts of diesel operated buses and trucks, of which many are somewhat old and operated underinefficient conditions which produce frequently black smoke visible fumes.It is well known that sulphur content of diesel fuelcontributes largely to the emission of particulatematter in diesel operated vehicles. Condensedsulphates coming from sulphur tend to enclosesoot masses, protecting them from oxidation anddestruction (see figure taken from MattiMaricq,M.).It is also well known that diesel engines generatemuch larger PM emissions than gasoline engines.Table 1, (based on low estimate emission dataadapted from Geller,M, et al, with vehicle andhigh estimate emission data taken from Toro M.Et al), shows a comparative estimation of yearlyPM2.5 vehicle emissions for the studied region.The estimates presented vary largely due to theeffect of vehicle age, pollution control devicesemployed and operational conditions. Theassumed estimates for the region consider theexistence of significant amounts of older vehicles, Figure 1. Artistic conception of diesel PM – takenlack of pollution control devices and low from Matti Maricq, M.operative standards.
  2. 2. Table 1. Estimated yearly PM2.5 vehicle emissions in the Aburrá Valley region Type of vehicle Units Diesel Gasoline Total Number of vehicles 86,972 571,109 658,081 Distance travelled per vehicle-year Km 20,000 6,000 7,850 Emission factor for PM2.5 , low estimate mg/km 7.57 0.35 2.78 Emission factor for PM2.5 , high estimate mg/km 468.0 41.6 185.2 Emission factor for PM2.5 , laboratory study mg/km 221.9 ND Yearly emissions, assumed estimate tons/year 600 105 705Under the support of the Area Metropolitana del Valle de Aburrá (the regional environmental authority) andECOPETROL (the national petroleum company) a research project was undertaken to examine the effect ofthe lowering of the diesel sulphur content on the PM2.5 composition and concentration. There is considerabledata in the region on total PM, which has been studied since the early 80’s and some data on PM 10, taken inthe last five years. But PM2.5 has been studied only in a few sampling stations during the last two years.Table 2 shows the studied PM2.concentrations for five zones in the region (24 hour samples) before thesulphur content of the diesel fuel was lowered. Samples of table 2 were taken in 2009 and the first fivemonths of 2010. The established annual standard for air quality in this area is 25µg/Nm3 . The table alsoshows the major chemical compositions (taken from Gomez et al and this study) Table 2. PM2.5 concentrations in stations in the studied region, micrograms/Nm3 and PM2.5chemical composition (average % +/- 1.5 standard deviations) before changes in S content in diesel Stations Unal Poli S. Antonio Bello Itagüí All stations Samples 7 7 38 30 30 112 PM 2.5 conc. 27.6+/-6.7 32.7+/-17.4 37.2+/-9.6 43.1+/27.7 25.9+/-10.7 33.7+/-17.6 OC 20.7+/-4.3 25.14+/-4.5 20.48+/-5.1 25.68+/-6.4 26.02+/-5.5 23.78+/-4.3 EC 40.11+/-5.0 23.31+/-5.7 37.18+/-7.0 30.4+/-10.5 26.56+/-7.0 31.53+/-7.6 Sulfates 12.66+/-2.6 16.26+/-3.4 15.35+/-7.6 13.9+/-2.41 15.1+/-4.62 14.69+/-3.3 Nitrates 0.35+/-0.11 0.62+/-0.21 1.35+/-1.46 0.75+/-0.42 1.33+/-1.16 0.98+/-0.73 Sodium 1.21+/-0.35 1.92+/-0.67 1.26+/-0.68 1.23+/-0.32 2.87+/-1.74 1.71+/-0.93 Ammonium 4.01+/-1.38 4.68+/-1.71 5.28+/-2.52 4.23+/-0.98 3.87+/-1.42 4.44+/-1.23 SO3 1.09+/-0.29 1.45+/-1.22 0.46+/-0.74 1.21+/-0.67 0.65+/-0.47 0.90+/-0.58 SiO2 1.36+/-0.67 1.86+/-0.95 1.04+/-0.83 1.07+/-1.56 1.64+/-1.01 1.33+/-0.79 Fe2O3 0.64+/-0.45 0.99+/-0.79 0.65+/-0.46 0.82+/-0.36 0.76+/-0.21 0.76+/-0.302. METHODOLOGYLaboratory emission sampling in a diesel motor bench. This was using a motor (ISUZU 4JA1 Type Iturbocharged, rotating pump direct injection, 2499 cm3, four cylinders in line, compression ratio 18.4,nominal power 59 KW at 4100 rpm), working with fuel with three sulphur contents: 2,100, 500 and 50 ppmunder two different load conditions (4.75 and 24.0 kW), associated with two different motor rotating speeds.(1,770 and 2,420 rpm). Samples were taken with an isokinetic sampling unit capable of separating PMsamples in three fractions (<2.5, 2.5-10, >10 microns).Environmental sampling in a tunnel serving the Aburrá Valley region. Concentrations and samples ofPM2.5 in the FERNANDO GOMEZ MARTINEZ tunnel were taken during complete 24 hour periods, atseveral times in 2010, in which there was certainty about the sulphur content of the diesel fuel used by thevehicles in the Aburrá Valley region. In this way the said three types of diesel fuel, with S content 2,100, 500and 50 ppm could be correlated with the samples.Environmental sampling in two sites in the Aburrá Valley region. For these samples, two (2) PQ-200,BGI Instrument, (equipped with Teflon and Quartz filters) were placed two (2) zones of the Aburrá Valley[Instituto Politecnico Jaime Isaza Cadavid (Poli) and Universidad Nacional- Facultad de Minas (Unal)] in six(6) alternate measurement campaigns, with two simultaneous ones for both sites. Samples were taken duringcomplete 24 hour periods, in such a way that they could be correlated with the ongoing changes in the dieselfuel S content (2,100, 500 and 50 ppm respectively). A total of 50 samples were collected in each area.
  3. 3. In the three studies, samples were taken with Tefón and Quartz filters and subjected to chemical analysis inLaboratory Alpha in Colombia for metallic oxides and in the DRI (Reno, Nevada) for ions and carbonaceousspecies (EC and OC). Analytical techniques used were Spectrofluorometry, 3D Polarized Energy DispersiveX-Ray Fluorescence (Epsilon Model 5), for the determination of mineral oxides; ion chromatography(Dionex Model 3000) for the quantification of anions and cations; and the IMPROVE-A Thermal MethodProtocol for the determination of organic carbon and elemental carbon.3. RESULTS AND DISCUSSIONTable 3 shows the major results obtained in the laboratory bench motor study. The results are expressed asspecific emission factors. Table 3. PM 2.5 specific emissions in diesel laboratory bench motor study Sulfur in diesel fuel, ppm 50 500 2,100 50 500 2,100 Motor rotational speed, rpm 1,770 1,770 1,770 2,420 2,420 2,420 Motor mechanical power, kW 4.69 4.76 4.75 24.1 23.9 23.9 PM 2.5 emissions, kg/ton fuel 3.76 5.50 8.76 0.81 0.78 2.55 OC, kg/ton fuel 2.234 3.303 5.239 0.275 0.218 0.526 EC, kg/ton fuel 0.060 0.068 0.175 0.293 0.328 0.949 Sulfates, kg/ton fuel 0.0396 0.1166 0.1638 0.0130 0.0203 0.6244 Nitrates, kg/ton fuel 0.0468 0.0554 0.0383 0.0046 0.0036 0.0032 Sodium, kg/ton fuel 0.0479 0.0549 0.0501 0.0043 0.0068 0.0292 OC, % of PM 2.5 59.42 60.01 59.83 34.09 28.16 20.63 EC, % of PM 2.5 1.60 1.24 1.99 36.35 42.31 37.22 Sulfates, % of PM 2.5 1.05 2.12 1.87 1.62 2.61 24.49Figures 2 and 3 show that PM 2.5 and sulfate in PM 2.5 emissions diminish with lower S in diesel fuel. Theeffect depends on motor load. 10 0.8 Sulfates in PM 2.5 PM 2.5, kg/ton fuel. 2 8 2 R = 0.98 0.6 R = 0.96 kg/ton fuel. 6 0.4 2 R = 0.81 4 2 0.2 R = 0.95 0.0 2 0 0 1,000 2,000 3,000 0 800 1,600 2,400 S in diesel, ppm S in diesel, ppm PM 2.5 kg/ton fuel at 4.75 kW, average = 6.01 S ulfates kg/ton fuel at 4.75 kW, average = 0.11 PM 2.5 kg/ton fuel at 24 kW, average = 1.38 S ulfates kg/ton fuel at 24 kW, average = 0.22 Figure 2. Specific PM2.5 emissions and S in fuel Figure 3. Sulfates in PM2.5 emissions and S in fuelTable 4 shows some major results obtained in the 5.00tunnel study. Figure 4 shows a clear diminution of 4.00 % of PM 2.5 .sulfate salts in the PM 2.5 with the lowering of thesulfur in the diesel fuel. 3.00 2.00 Table 4 major results in study in tunnel 1.00 S in diesel fuel, ppm 2,100 500 50 0.00 PM 2.5 microgr./m3 225 420 249 0 800 1,600 2,400 Vehicles per hour 268 389 361 S in diesel, ppm OC in PM 2.5 , % 23.8 22.7 25.8 S ulfates Amonium Ions, total EC in PM 2.5 , % 56.3 59.5 55.5 Sulfates in PM2.5 , % 2.10 1.23 0.50 Figure 4. Soluble salts in PM2.5 in tunnel
  4. 4. Table 5 shows the results of the study done in the two sites in the city during the ongoing changes in thediesel fuel composition. Table 5. PM2.5 concentrations in stations in the studied region, micrograms/Nm3 and PM2.5 chemical composition (average % +/- 1.5 standard deviations) during changes in diesel S content Station Poli Unal Poli Unal Poli Unal S in fuel, ppm 2,100 2,100 500 500 50 50 PM 2.5, micrg/m3 32.7+/-17.4 27.6+/-6.9 26.6+/-22.3 31.4+/-13.6 27.9+/-11.4 32.8+/-12.8 OC, % 25.14+/-4.4 20.7+/-4.3 27.6+/-6.3 22.6+/-5.8 27.5+/-4.8 23.4+/-5.0 EC, % 23.3+/-5.7 40.1+/-5.0 27.6+/-10.4 44.2+/-9.3 25.9+/-6.3 44.7+/-6.2 Sulfates, % 16.26+/-3.4 12.66+/-2.6 11.69+/-7.2 7.44+/-3.7 11.25+/-3.3 7.14+/-1.8 Nitrates, % 0.62+/-0.21 0.35+/-0.11 0.56+/-0.51 0.45+/-0.48 0.55+/-0.32 0.57+/-0.75 Sodium, % 1.92+/-0.67 1.21+/-0.35 1.94+/-1.31 1.03+/-0.77 1.77+/-0.78 0.79+/-0.55 Ammonium, % 4.68+/-1.71 4.01+/-1.38 2.11+/-2.4 2.07+/-1.77 2.86+/-1.3 2.15+/-1.57 SO3, % 1.45+/-1.22 1.09+/-0.29 1.01+/-0.77 1.09+/-1.63 1.49+/-1.16 0.80+/-0.38 SiO2, % 1.86+/-0.95 1.36+/-0.67 2.0+/-1.58 1.64+/-1.33 2.45+/-2.38 1.19+/-1.09 Fe2O3, % 0.99+/-0.79 0.64+/-0.45 1.54+/-0.99 1.16+/-0.85 1.9+/-0.89 1.01+/-0.49Figures 5 to 8 show the PM 2.5 concentrations during the entire sampling campaign, including de previousdata taken in the Bello, Itagüi and San Antonio stations. 160 2100 30 Sulfates in PM2.5 % . PM2.5 conc. 120 1400 20 S ppm 80 700 10 40 0 0 0 0 120 240 360 0 120 240 360 S ampling day, starting 2009/11/17 Day of sampling (starting 2009/11/17) PM 2.5, micrograms/m3, av= 31.5 +/- 14.0 S in diesel, ppm Itagüi Bello S an Antonio Poli UnalFigure 5. PM 2.5 and changes in S in diesel fuel Figure 7 Sulfates in PM 2.5 for the stations 160 30 PM 2.5 micrograms/m3 . Sulfate in PM 2.5,% . 25 120 20 15 80 10 40 5 0 0 0 800 1600 2400 0 800 1600 2400 S in diesel ppm S in diesel ppm Itagüi Bello S an Antonio Poli UnalFigure 6. PM 2.5 for each diesel S content value Figure 8 Sulfates in PM 2.5 and S content in diesel fuel4. CONCLUSIONA clear link was established between diesel sulfur content and PM 2.5 compositions and concentrations, whichindicates the large influence of diesel fuel vehicles impact on the pollution situation in the region and theimportance of this sulfur diminution. The impact is quite clear on the chemical PM 2.5 compositions whichshow a significant diminution of sulfates and ammonium salts. The impact on concentrations is detectablebut is affected by the operational conditions of diesel equipment, vehicle age and operational practices.
  5. 5. 5. REFERENCESArango,J. Calidad de los Combustibles en Colombia. 2008. ECOPETROL.Geller,M., Ntziachristos, L,, Mamakos A., Zissis Samaras, D., Schmitz, J., Sioutas,C. Physicochemical and redoxcharacteristics of particulate matter (PM) emitted from gasoline and diesel passenger cars. 2006. AtmosphericEnvironment. Vol 40. Issue 36, 6988-7004.Gómez, M., Dawidowski, L., Posada, E., Correa, M., Saldarriaga, J., Chemical Composition of PM2.5 in three zones of theAburrá Valley, Colombia. 2011. Poster #702 presented at the A&WMA 2011 Annual Meeting, Orlando, USA.Matti Maricq, M. Chemical characterization of particulate emissions from diesel engines: A review. 2007. Journal ofAerosol Science, Vol 38, Issue 11, 1079-1118.Toro M., Ramírez, J., Quiceno, R.,Zuluaga, C. Cálculo de la emisión vehicular de contaminantes atmosféricos en laciudad de Medellín mediante factores de emisión CORINAIR. 2001, Revista ACODAL, 191, 42-49

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