THE EFECT OF THE DIESEL FUEL SULPHUR CONTENT ON THE PM2.5

POLLUTION PROBLEM IN THE ABURRÁ VALLEY REGION AROUND MEDELLÍN,

COLOMBIA

Enrique Posada (1) , Myriam Gómez (2)

(1) INDISA S.A ,Carrera 75 # 48 A 27, Medellín, Colombia

(2) Politécnico Colombiano, Medellín, Colombia

enrique.posada@indisa.com mgomez@elpoli.edu.co

8th International Conference on Air Quality - Science and Application in Athens, 19-23 March 2012.

THE ABURRÁ VALLEY REGION WITH THE CITY OF MEDELLÍN , COLOMBIA

Colombia is in South AmericaIt has a 46 million population

The Aburrá Valley 3.5 million people

Medellín 2.7 million people

diesel gasolina

Number of vehicles 90.000 590.000

Under the pressure of the environmental authorities, the national provider of diesel fuel decided to supply the region with low sulfur diesel, to contribute to the lowering of the PM2.5 concentrations in the air.

S contents went down from 2,100 ppm to 500 ppm and then to 50 ppm between the end of 2009 and the first six months of 2010

The region counts with a metropolitan metro train very well cared by everybody under the “CULTURA METRO”

There are several innovative urban cable mass transportation systems and a new natural gas metro bus

But there are still large amounts of diesel operated buses and trucks, of which many are somewhat old and operated under inefficient conditions which produce frequently black smoke visible fumes.

Type of vehicle Units Diesel Gasoline Total

Number of vehicles 86,972 571,109 658,081Distance 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

Estimated yearly emissions tons/year 600 105 705

Estimated yearly PM2.5 vehicle emissions in the Aburrá Valley region

Diesel engines generate much larger PM emissions than gasoline engines.

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+/-0.30

Table 2. PM2.5 concentrations in stations in the studied region, micrograms/Nm3 and PM2.5

chemical composition (average % +/- 1.5 standard deviations) before changes in S content in diesel

Laboratory emission sampling in a diesel motor bench. Motor (ISUZU 4JA1 Type I turbocharged, rotating pump direct injection, 2499 cm3, four cylinders in line, compression ratio 18.4, nominal power 59 KW at 4100 rpm)Fuel with three sulfur contents: 2,100, 500 and 50 ppmTwo 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 PM samples in three fractions (<2.5, 2.5-10, >10 microns).

Environmental sampling in a tunnel serving the Aburrá Valley regionConcentrations and samples of PM2.5 in the FERNANDO GOMEZ MARTINEZ tunnel were taken during complete 24 hour periods, at several times in 2010, in which there was certainty about the sulfur content of the diesel fuel used by the vehicles in the Aburrá Valley region. In this way the said three types of diesel fuel, with S content 2,100, 500 and 50 ppm could be correlated with the samples.

Environmental sampling in two sites in the Aburrá Valley regionTwo (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 during complete 24 hour periods, in such a way that they could be correlated with the ongoing changes in the diesel fuel S content (2,100, 500 and 50 ppm respectively). A total of 50 samples were collected in each area.

Analysis

In the three studies, samples were taken with Tefón and Quartz filters and subjected to chemical analysis in Laboratory Alpha in Colombia for metallic oxides and in the DRI (Reno, Nevada) for ions and carbonaceous species (EC and OC). Analytical techniques used were Spectrofluorometry, 3D Polarized Energy Dispersive X-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 Method Protocol for the determination of organic carbon and elemental carbon.

Sulfur in diesel fuel, ppm 50 500 2,100 50 500 2,100Motor rotational speed, rpm 1,770 1,770 1,770 2,420 2,420 2,420Motor 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 24.49

PM 2.5 specific emissions in diesel laboratory bench motor study

R2 = 0.98

R2 = 0.95

0

2

4

6

8

10

0 800 1,600 2,400S in diesel, ppm

PM

2.5

, kg/

ton

fu

el.

PM 2.5 kg/ton fuel at 4.75 kW, average = 6.01

PM 2.5 kg/ton fuel at 24 kW, average = 1.38

R2 = 0.81

R2 = 0.96

0.00.20.40.60.8

0 1,000 2,000 3,000

S in diesel, ppm

Su

lfat

es in

PM

2.5

kg/

ton

fu

el.

Sulfates kg/ton fuel at 4.75 kW, average = 0.11

Sulfates kg/ton fuel at 24 kW, average = 0.22

PM 2.5 and sulfate in PM 2.5 emissions diminish with lower S in diesel fuel.

The effect depends on motor load.

S in diesel fuel, ppm 2,100 500 50

PM 2.5 micrograms/m3 225 420 249

Vehicles per hour 268 389 361

OC in PM 2.5 , % 23.8 22.7 25.8

EC in PM 2.5 , % 56.3 59.5 55.5

Sulfates in PM2.5 , % 2.10 1.23 0.50

Major results in study in tunnel

0.00

1.00

2.00

3.00

4.00

5.00

0 800 1,600 2,400S in diesel, ppm

% o

f P

M 2

.5 .

Sulfates Amonium Ions, total

In the tunnel there was a clear diminution of sulfate salts in the PM 2.5 with the lowering of the sulfur in the diesel fuel.

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+/-0.49

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

0

40

80

120

160

0 120 240 360Sampling day, starting 2009/11/17

PM

2.5

con

c.

0

700

1400

2100

S p

pm

PM 2.5, micrograms/m3, av= 31.5 +/- 14.0

S in diesel, ppm

0

40

80

120

160

0 120 240 360Sampling day, starting 2009/11/17

PM

2.5

con

c.

0

700

1400

2100

S p

pm

PM 2.5, micrograms/m3, av= 31.5 +/- 14.0

S in diesel, ppm

0

10

20

30

0 120 240 360

Day of sampling (starting 2009/11/17)

Su

lfat

es in

PM

2.5

% .

Itagüi Bello San Antonio Poli Unal

0

5

1015

20

25

30

0 800 1600 2400S in diesel ppm

Su

lfat

e in

PM

2.5

,% .

Itagüi Bello San Antonio Poli Unal

PM 2.5 and sulfate in PM 2.5 concentrations diminish with lower S in diesel fuel for the samples taken in the urban areas.

CONCLUSION

A clear link was established between diesel sulfur content and PM 2.5 compositions and concentrations, which indicates the large influence of diesel fuel vehicles impact on the pollution situation in the region and the importance of this sulfur diminution. The impact is quite clear on the chemical PM 2.5 compositions which show a significant diminution of sulfates and ammonium salts.The impact on concentrations is detectable but is affected by the operational conditions of diesel equipment, vehicle age and operational practices.The impact was detectable in PM2.5 urban concentrations and sulfate salts in PM2.5

Thank you very much for your kind attention

COLOMBIA IS PASSION