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Atmospheric Environment 40 (2006) 1601–1609

www.elsevier.com/locate/atmosenv

Impact of using fishing boat fuel with high poly aromatic contenton the emission of polycyclic aromatic hydrocarbons

from the diesel engine

Yuan-Chung Lina, Wen-Jhy Leea, Hsing-Wang Lia, Chung-Ban Chenb,Guor-Cheng Fangc, Perng-Jy Tsaid,�

aDepartment of Environmental Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, TaiwanbHeavy Duty Diesel Engine Emission Group, Refining and Manufacturing Research Center, Chinese Petroleum Corporation,

Chia-Yi 60036, TaiwancDepartment of Environmental Engineering, Hungkuang University, Sha-Lu, Taichung, Taiwan

dDepartment of Environmental and Occupational Health, Medical College, National Cheng Kung University, 138, Sheng-Li Road,

Tainan 70428, Taiwan

Received 28 June 2005; received in revised form 7 November 2005; accepted 7 November 2005

Abstract

Because of the fishery subsidy policy, the fishing boat fuel oil (FBFO) exemption from commodity taxes, business taxes

and air pollution control fees, resulted in the price of FBFO was �50% lower than premium diesel fuel (PDF) in Taiwan.

It is estimated that �650,000 kL FBFO was illegally used by traveling diesel-vehicles (TDVs) with a heavy-duty diesel

engine (HDDE), which accounted for �16.3% of the total diesel fuel consumed by TDVs. In this study, sulfur, poly

aromatic and total-aromatic contents in both FBFO and PDF were measured and compared. Exhaust emissions of

polycyclic aromatic hydrocarbons (PAHs) and their carcinogenic potencies (BaPeq) from a HDDE under transient cycle

testing for both FBFO and PDF were compared and discussed. Finally, the impact caused by the illegal use of FBFO on

the air quality was examined. Results show that the mean sulfur-, poly aromatic and aromatic-contents in FBFO were 43.0,

3.89 and 1.04 times higher than that of PDF, respectively. Emission factors of total-PAHs and total-BaPeq obtained by

utilizing FBFO were 51.5 and 0.235mgL�1-Fuel, which were 3.41 and 5.82 times in magnitude higher than obtained by

PDF, respectively. The estimated annual emissions of total-PAHs and total-BaPeq to the ambient environment due to the

illegally used FBFO were 23.6 and 0.126 metric tons, respectively, which resulted in a 17.9% and a 25.0% increment of

annual emissions from all mobile sources, respectively. These results indicated that the FBFO used illegally by TDVs had a

significant impact on PAH emissions to the ambient environment.

r 2005 Elsevier Ltd. All rights reserved.

Keywords: Fishery subsidy policy; Fishing boat fuel oil; Diesel fuel; PAH emissions; Carcinogenic potencies

e front matter r 2005 Elsevier Ltd. All rights reserved

mosenv.2005.11.013

ing author. Tel.: +886 6 2353535x5806;

2484.

ess: pjtsai@mail.ncku.edu.tw (P.-J. Tsai).

1. Introduction

For many countries, the fishery subsidy is one ofimportant measures to preserve their fisheries.However, the current opinions of World Trade

.

ARTICLE IN PRESSY.-C. Lin et al. / Atmospheric Environment 40 (2006) 1601–16091602

Organization (WTO) members have taken twoopposing extremes on the policy of the fisherysubsidy (WTO, 2003). Among all, one of theimportant fishery subsidy measurements is theexemption of the fishing boat fuel oil (FBFO) fromcommodity taxes, business taxes and air pollutioncontrol fees, which results in the price of FBFO is�50% lower than that of premium diesel fuel (PDF)in Taiwan. The government in Taiwan found that agreat amount of FBFO had been used illegally bytraveling diesel-vehicles (TDVs) with a heavy-dutydiesel engine (HDDE). Yet, it is true that the use ofFBFO in TDVs does cause more PM emission andthe impairment of fuel nozzles. Nevertheless, thecost arising from nozzle replacements is still muchcheaper than the cost arising from the use of PDF inTDVs which provides the incentive for the illegaluse of FBFO in Taiwan. In 2003, the actual annualFBFO consumption was 1,953,000 kL. We esti-mated the trend for the increment of FBFO annualconsumptions based on the long-term consumptionrecords from 1950 to 2002, and obtained anestimated value for FBFO consumption in 2003was approximately 1,303,000 kL. In this study, thedifference between the actual and the estimatedvalues (650,000 kL) was regarded as the fraction ofFBFO which was illegally used in 2003, whichaccounted for �16.3% of total diesel fuel consumedby TDVs ( ¼ 3,985,671 kL).

Diesel-powered engines have high fuel efficiency,power output, fuel economy and lower emissions oftraditional pollutants such as hydrocarbons (HCs),nitrogen oxides (NO) and carbon monoxide (CO)than gasoline-powered engines (Williams et al.,1989; Schinder, 1992). Diesel-powered engines areused worldwide in heavy-duty buses, trucks, con-struction machines and generators, etc. However,emissions of smoke, particulate matter (PM), sulfuroxide (SOx), polycyclic aromatic hydrocarbons(PAHs) and exhaust odor from the exhaust of aHDDE have always been a concern for the publicand environmental researchers (Barfknecht, 1983;Lee et al., 1995; Harrison et al., 1996; Yang et al.,1999). Many researchers have suggested that mobilesources are the major contributor to PAH concen-trations in urban and suburban environments. Yanget al. (1999) indicated that the contribution of total-PAHs from mobile sources to ambient air were91.8% at the traffic intersections studied. Total-PAH concentrations in the ambient air of thetraffic-source averaged approximately 5.3 and 8.3times higher than mean values in the urban and

rural atmosphere, respectively (Lee et al., 1995).Moreover, Barfknecht indicated that the PAHemission factors from HDDE exhaust was 10-foldhigher than that from gasoline engines (Barfknecht,1983). Analytical results show TDVs are thedominant source of PAHs in the city traffic jamsand the major contributor to the total amount ofPAHs in Taiwan. In the past 30 years, many studieshave suggested that PAHs are environmentalimmunosuppressive contaminants. PAHs, especiallybenzo(a)pyrene, not only injure the respiratory andimmune system but also cause cell mutation andcancers such as lung and skin (Knize et al., 1999;Hecht, 1999; Yousef et al., 2002; Page et al., 2002;Laupeze et al., 2002; Grevenynghe et al., 2003).There is no doubt that FBFO used illegally byTDVs might have a significant effect on air qualityand human health.

The air pollutions in HDDE exhaust is directlyrelated to those in diesel fuel such as fuel cetaneindex, density, distillation temperature at both 90%and 95%, aromatic content, poly aromatic content,fuel sulfur content, and operation parameters(Westerholm and Li, 1994; Collier et al., 1995;Sjogren et al., 1995; Hori et al., 1997; Yang et al.,1998; Mi et al., 2000). For a given type of fuel undera specified operation condition, it can be expectedthat the amount of sulfur, aromatic, and polyaromatic contents in fuel might affect pollutantemissions. Based on this, this study first probes intothe measures of sulfur, poly aromatic and aromaticcontents in FBFO and PDF. Second, PAH emis-sions from HDDE exhaust were compared anddiscussed by using FBFO and PDF, respectively.Finally, the impact of illegally used FBFO by TDVson PAH emissions from diesel vehicles and mobilesources were evaluated.

2. Methods and materials

2.1. Engine and dynamometer system

There are two test fuels used in this study: PDFand FBFO; both were bought at the gas station.Testing procedure was according to Code of FederalRegulations (CFR) 40, Part 86, Subpart N (US-HDD Transient Cycle). A dilution tunnel andmonitoring system were both installed downstreamof diesel engine exhaust and supplied diluted air in aappropriate ratio and for continuous measurementof smoke, suspended particles and gas-phase pollu-tants. The heavy-duty diesel engine (non-catalyst)

ARTICLE IN PRESSY.-C. Lin et al. / Atmospheric Environment 40 (2006) 1601–1609 1603

used was a Cummins B5.9-160 with the followingcharacteristics: six-cylinders; four strokes; directinjection; fuel injection sequence 1-5-3-6-2-4; boreand stroke of 102mm (Dia.) � 120mm; totaldisplacement of 5880ml; compression ratio of17.9:1, maximum horsepower of 118 kW at2500 rpm; and, maximum torque of 534Nm at1600 rpm. The testing procedure included varyspeed (rpm) and load (%) to simulate real trafficon an express way, in congested-urban and un-congested-urban environments. Cold start and hotstart emissions were measured and a complexemission index was calculated by multiplyingweighting factors (1/7� cold start+6/7� hot start).This type of HDDE is used in Taiwan for regulationtest of pollutant emissions.

2.2. Sample collection

PAHs samples of both particulate-phase and gas-phase were collected by using a PAH sampling systemat a temperature below 52 1C. Particulate-phase PAHswere collected on a glass-fiber filter. Before sampling,filters were placed in an oven at 450 1C for 8h to burnoff any organic compounds that might be present infilters. Finally, the cleaned filters were stored in adesiccator for at least 8 h for the moisture equilibriumbefore weighing. After the experiments, the filters werebrought back to the laboratory and put in a desiccatorfor 8h to remove moisture, they were weighed againto determine the net mass of particles collected. Gas-phase PAHs were collected on a three stages of glasscartridge containing polyurethane foam (PUF) plugfollowed XAD-16 resin. The glass cartridge waspacked with 5.0 cm of XAD-16 resin sandwichedbetween a 2.5-cm upper PUF plug and a 2.5-cmbottom PUF plug. Silicone glue was used to seal andhold these two pieces of PUF to prevent resin fromleaking out during sampling and extraction processes.After 8h of adherence, the newly PUF/resin cartridgewas cleaned up by Soxhlet extracting for one day eachwith distilled water, methanol, dichloromethane andfinally n-hexane for a total of 4 days and then thesePUF/resin cartridge was placed in a vacuum oven at60 1C for 2h to dry and to evaporate the residualsolvent in them. After drying, each PUF/resincartridge was individually wrapped in hexane-washedaluminum foil and was stored in a refrigerator at 4 1Cand transported in clean screw-capped jars withTeflon cap liners before sampling. Each glass fiberfilter was transported to and from the field in a glassbox, which was also wrapped with aluminum foil.

2.3. PAH analysis

Each collected sample (including particulate andgaseous PAH samples) was extracted in a Soxhletextractor with a mixed solvent (n-hexane anddichloromethane; vol/vol, 1:1; 500ml each) for24 h. The extract was then concentrated, cleanedup, and reconcentrated to exactly 1.0mL. The PAHcontents were determined with a Hewlett-Packard(HP) gas chromatograph (GC) (HP 5890A; Hewlett-Packard, Wilmington, DE, USA), a mass selectivedetector (MSD) (HP 5972), and a computer work-station (Aspire C500; Acer, Taipei, Taiwan). This GC/MSD was equipped with a capillary column (HPUltra 2, 50m� 0.32mm� 0.17mm) and an automaticsampler (HP-7673A) and operated under the follow-ing conditions: injection volume of 1mL; splitlessinjection at 310 1C; ion source temperature at 310 1C;oven temperature from 50 to100 1C at 20 1Cmin�1,100 to 290 1C at 3 1Cmin�1, and held at 290 1C for40min. The mass of primary and secondary PAHsions were determined by using the scan mode for purePAH standards. The PAHs were qualified by usingthe selected ion monitoring (SIM) mode.

PAH homologues grouped by the number ofrings are as follows: naphthalene(Nap) for 2-ring;acenaphthylene(AcPy), acenaphthene(Acp), fluore-ne(Flu), phenanthrene(PA), and anthracene(Ant)for 3-ring; fluoranthene(FL), pyrene(Pyr), ben-zo[a]anthracene(BaA), and chrysene(CHR) for 4-ring; cyclopenta[c,d]pyrene(CYC), benzo[b]fluor-anthene (BbF), benzo[k]fluoranthene(BkF), ben-zo[e]pyrene(BeP), benzo(a)pyrene(B[a]P), perylene(PER), dibenzo[a,h]anthracene(DBA), benzo[b]-chrycene(BbC) for 5-ring; indeno[1,2,3,-cd]pyre-ne(IND), benzo[ghi]perylene(Bghip) for 6-ring;and, coronene (COR) for 7-ring. According to themolecular weight, these 21 individual PAHs aredivided into three categories: low molecular weights(LM–PAHs containing two- and three-ringedPAHs); middle molecular weights (MM–PAHscontaining four-ringed PAHs); and, high molecularweights (HM–PAHs containing five- to seven-ringed PAHs). The total-PAH data for the HDDEexhaust were the summation of 21 individual PAHs.

The GC/MSD was calibrated with a dilutedstandard solution of 16 PAH compounds (PAHmixture-610M; Supelco, Bellefonte, PA, USA) plusfive additional individual PAHs obtained fromMerck(Darmstadt, Germany). Analysis of serialdilutions of PAHs standards showed the detectionlimit (DL) for GC/MSD was between 25 and 321 pg

ARTICLE IN PRESSY.-C. Lin et al. / Atmospheric Environment 40 (2006) 1601–16091604

for the 21 PAH compounds. The limit of quantifica-tion (LOQ) is defined as DL divided by thesampling volume or sampling time. The LOQ forindividual PAHs was between 22 and 284 pgm�3,while values for sampling time were between 75 and963 pg h�1. Ten consecutive injections of a PAH610-M standard yielded an average relative stan-dard deviation of GC/MSD integration area of6.86%, within a range of 4.29–9.67%. Following thesame experimental procedures used for sampletreatment, recovery efficiencies were determined byprocessing a solution containing known PAHconcentrations. This study showed the recoveryefficiencies for the 21 PAH compounds ranged from0.799 to 0.901, with an average value of 0.842.Analyses of field blanks, including aluminum foil,glass-fiber filters, and PUF/XAD-16 cartridges,revealed no significant contamination (GC/MSDintegrated areaodetection limit).

2.4. Data analysis

The total-PAH concentration was the sum of theconcentrations for the 21 PAH compounds in eachcollected sample. To assess PAH homolog distribu-tion for each collected sample, total-PAHs werefurther classified into three categories of theLM–PAHs, MM–PAHs, and HM–PAHs. More-over, considering that several PAH compounds areknown human carcinogens, the carcinogenic poten-cies of PAH emissions from each emission sourcewere also determined. In principle, the carcinogenicpotency of a given PAH compound is assessed onthe basis of its benzo[a]pyrene equivalent concen-tration (BaPeq). Calculation of the BaPeq concentra-tion for a given PAH compound uses its toxicequivalent factor (TEF), which represents therelative carcinogenic potency of the given PAHcompound, using benzo[a]pyrene as a reference

0.02

0.86

0.0

0.5

1.0

1.5

PDF FBFO PDF

Sulf

ur c

onte

nt (

wt %

)

1.8

0

2

4

6

8

10

Tot

al P

olya

rom

atic

cont

ent (

wt %

)

(A) (B)

Fig. 1. The sulfur, total-poly aromatic and total-aromatic contents i

respectively.

compound to adjust its original concentration. Onlya few proposals for TEFs are available. In this studythe TEFs completed by Nisbet and LaGoy (Nisbetand LaGoy, 1992) were employed. On the basis ofthis TEF, the carcinogenic potency of total-PAHs(i.e., total-BaPeq) was assessed by the sum of theBaPeq concentrations estimated for each PAHcompound with a TEF in the total-PAHs.

3. Results and discussion

3.1. Fuel specification

The mean sulfur, total-poly aromatic and total-aromatic contents in FBFO were 0.86, 7.0 and25.3wt%, respectively; they were 43.0, 3.89 and 1.04times higher in magnitude than the correspondingfigures for PDF (Fig. 1). Analytical results sug-gested that TDVs using FBFO significantly in-creased the SOx by more than 40 times whencompared with PDF. Furthermore, the high contentof poly aromatics in FBFO, was responsible for theTDVs’ high potential for emitting carcinogenicPAHs to ambient air. Other fuel specifications werelisted in Table 1.

3.2. Emission of traditional pollutants

As shown in Table 2, the emission factor of PM inthe exhaust of HDDE fed with FBFO was0.296 gBHP�1 h�1, 3.15 times of magnitude higherthan HDDE fed with PDF. That is because the T90,final boiling point (FBP) and viscosity of FBFO(347.6 1C, 384 1C, 3.887 CST; see Table 1) werehigher than those of PDF(314.3 1C, 357.9 1C, 2.433CST; see Table 1), causing that FBFO was not easyto burn than PDF. Previous research indicated thatdiesel fuel sulfur content and boiling point had anabsolute relation to PM emission from HDDE

FBFO PDF FBFO

7.0

24.325.3

20

22

24

26

28

30

Tot

al a

rom

atic

cont

ent (

wt%

)

(C)

n premium diesel fuel (PDF) and fishing boat fuel oil (FBFO),

ARTICLE IN PRESS

Table 1

Specifications of the premium diesel fuel (PDF) and fishing boat fuel oil (FBFO), respectively

Fuel parameter Premium diesel fuel (PDF) Fishing boat fuel oil (FBFO) Analytical method

Density (gml�1 at 15 1C) 0.823 0.845 ASTMa D-287

Flash point (1C) 72 93 ASTM D-93

Pour point (1C) �15 �3 ASTM D-97

Viscosity (CST at 40 1C) 2.433 3.887 ASTM D-445

Cetane index 53.4 53.3 ASTM D-976

Cetane number 52.6 52.7 ASTM D-976

Carbon residue (wt%) 0.09 0.14 ASTM D-524

Distillation, IBPb (1C) 194.5 215.8 ASTM D-86

T10 (1C) 218 248.2 ASTM D-86

T20 (1C) 228.1 261 ASTM D-86

T50 (1C) 254.1 293 ASTM D-86

T90 (1C) 314.3 347.6 ASTM D-86

FBP (1C) 357.9 384 ASTM D-86

Residue (vol%) 1.5 1.2 ASTM D-524

GHVc (kcal kg�1) 10,217 10,367 ASTM D-240

aAmerican Society for Testing Materials.bInitial boiling point.cGross heat value.

Table 2

Emission factor of traditional pollutants in the exhaust of HDDE

(gBHP�1-h�1)

Traditional

pollutants

Premium diesel

fuel (PDF)

Fishing boat

fuel oil (FBFO)

FBFO/PDF

PM 0.094 0.296 3.15

THC 0.376 0.242 0.644

CO 1.91 2.01 1.05

CO2 756 789 1.04

NOx 6.54 6.71 1.03

Y.-C. Lin et al. / Atmospheric Environment 40 (2006) 1601–1609 1605

exhaust (Arai, 1992; Rantanen et al., 1993; Horiet al., 1997). The same phenomenon was found inthis study. The sulfur content in FBFO was alsohigher than that in PDF (Fig. 2). Moreover, a largeproportion of incompletely burned hydrocarbonadhered to particulates and lead into the emissionfactors of total hydrocarbon (THC) of FBFO waslower than that of PDF. The emission factors ofCO, CO2 and NOx for FBFO were slightly higher(3–5%) than those corresponding for PDF. Butbecause the concentrations of CO, CO2 and NOx

emitted from TDVs by using both FBFO and PDFwere quite high, which led to no significantdifference could be found statistically. Nevertheless,the TDVs’ primary problem was the HDDEemission of PM, SOx and PAHs. Analytical resultsclearly suggested that the illegal use of FBFO byTDVs increased the emission of PM, and SOx.

3.3. PAH concentration in the exhaust of heavy-duty

diesel engine (HDDE)

In this study, each of the three-stage PUF/resinglass cartridges was analyzed. We found that lessthan 5% of total gas-phased PAHs (i.e. stage1+stage 2+stage 3) were collected by stage 3 suggest-ing the breaking through of gas-phase PAHs wasnegligible. We also found that PAH emissionsarising from the cold start was only slightlyhigher (o5%) than that from hot start in bothPDF and FBFO. But there was no significantdifference could be found statistically. This ismainly because the air temperature in Taiwan wasquite high, which led to the engine operatingtemperature in cold start would reach the steady-state within 1min. But it should be noted that itmight cause a significant difference when tested inthe frigid zones.

Table 3 illustrates the PAH concentration ofcomplex emission index in HDDE exhaust by usingPDF and FBFO. The mean total-PAH concentra-tion for FBFO used by HDDE was 4230 mgNm�3;this figure was 3.20 times higher than that for PDF(1320 mgNm�3). Comparing those of FBFO andPDF, the total-PAH concentration ratio in dieselengine exhaust (so called EE ratio ¼ 3.20) was verysimilar to the total-poly aromatic content ratio inthe fuels (so called F ratio ¼ 3.89). Analyticalresults verified that the total-poly aromatic content

ARTICLE IN PRESS

15.1

51.5

01020304050607080

PDF FBFO

PDF FBFO

EF t

otal

-PA

Hs

mg/

L4.42

14.8

0

5

10

15

20

PDF FBFO

PDF FBFO

EF t

otal

-PA

Hs m

g/B

HP-

hr

0.0404

0.235

0

0.1

0.2

0.3

0.4

EF t

otal

-BaP

eq m

g/L

0.0118

0.0672

0

0.05

0.1

EF t

otal

-BaP

eq m

g/B

HP-

hr

(C)

(D)(B)

(A)

Fig. 2. Emission factors of total-PAHs and total-BaPeq from the exhaust of HDDE in the unit of mgL�1 and mgBHP�1-h�1, respectively.

Table 3

PAH concentration (gaseous+particulate phase) in the exhaust of HDDE

PAHs PDF (n ¼ 3) FBFO (n ¼ 3)

Mean (mgm�3) RSD (%) Mean (mgm�3) RSD (%)

Nap 1100 18.6 2758 17.6

AcPy 66.9 22.3 411 18.2

Acp 35.2 27.2 264 20.7

Flu 37.4 21.7 245 19.8

PA 54.6 23.3 377 21.5

Ant 7.17 26.3 53.3 26.8

FL 5.66 30.5 36.1 21.8

Pyr 5.70 32.4 38.8 18.2

CYC 0.341 27.2 2.28 27.1

BaA 0.105 29.7 0.951 32.8

CHR 0.236 19.7 1.98 23.0

BbF 0.351 28.7 2.52 26.4

BkF 0.303 26.4 1.87 29.5

BeP 0.401 31.5 3.02 22.0

BaP 1.61 21.1 10.7 19.3

PER 0.426 27.7 3.22 19.7

IND 1.52 19.9 9.65 25.4

DBA 0.315 24.4 2.34 19.7

BbC 0.337 28.7 2.72 33.6

BghiP 0.397 29.6 2.89 24.4

COR 0.329 31.3 2.30 25.5

PLM�PAHs 1300 19.2 4109 18.6

PMM�PAHs 11.7 31.2 77.9 20.2

PHM�PAHs 6.32 25.0 43.5 23.4

Total PAHs 1320 19.3 4230 18.7

Total BaPeq 3.53 21.0 19.3 19.9

Y.-C. Lin et al. / Atmospheric Environment 40 (2006) 1601–16091606

ARTICLE IN PRESSY.-C. Lin et al. / Atmospheric Environment 40 (2006) 1601–1609 1607

in the fuel is a key factor affecting PAH emissionfrom HDDE exhaust.

The mean total-BaPeq concentration for HDDEexhaust burning FBFO was 19.3 mgNm�3, 5.47times higher than that of PDF. Therefore, the EEratio of total-BaPeq concentration (5.47) is signifi-cantly higher than the F ratio of total-poly aromaticcontent (3.89). Analysis of experimental resultsrevealed that the carcinogenic risk of exhaust fromFBFO diesel engine is dramatically higher than forthe total-poly aromatic content in the fuel.

Furthermore, the concentration ofP

LM–PAHs,PMM–PAHs, and

PHM–PAHs for HDDE burn-

ing FBFO were 4109, 77.9 and 43.5 mgNm�3,respectively, and 3.16, 6.66 and 6.88 times higherthan that of PDF, respectively. If the individualPAHs were investigated in more detail, eachindividual PAH concentration emitted by burningwere all higher than that of PDF. The ratios ofindividual PAH concentrations for FBFO and PDFwere between 2.51 and 9.05 (increased from low tohigh molecular weight PAHs). It is known that thehigher molecular weight of PAHs, the highercarcinogenic potency can be expected (i.e., higherTEF value). The above results further confirm thatEE ratio of total-BaPeq concentration ( ¼ 5.47) issignificantly higher than the EE ratio of total-PAHconcentration ( ¼ 3.20). In other words, our experi-mental results also confirmed that TDVs usingFBFO with a high poly aromatic content dischargedconsiderable amount of hazardous PAHs into theambient air.

3.4. Emission factors of PAHs emitted from HDDE

The generation and/or depletion mechanisms ofPAHs in a high temperature combustion processfollowed three pathways: pyrosysthesis (Bjørseth,1983); direct emission with unburned fuel (Williamset al., 1989); and, the thermodynamic destructibility ofthe PAHs molecule (Tancell et al., 1995). In this study,experimental data did not allow us to clearly identifyPAH generation and/or depletion mechanisms.Nevertheless, PAH emission factors (mgL�1-fuel ormg�1BHP-h) on both total-PAHs and total-BaPeq(denoted EFtotal-PAHs and EFtotal-BaPeq, respectively)were calculated. As shown in sequence for magnitudesof EFtotal-PAHs and EFtotal-BaPeq in mgL�1-fuel,analysis identified FBFO (51.5mgL�1-fuel)4PDF(15.8mgL�1-fuel) and FBFO (0.235mgL�1-fuel)4PDF (0.0404mgL�1-fuel), respectively(Figs. 2A, B). A similar trend was also identified

for EFtotal-PAHs and EFtotal-BaPeq in mgBHP�1-h�1:FBFO (14.8mgBHP�1-h�1)4PDF (4.42mgBHP�1-h�1) and FBFO (0.0672mgBHP�1-h�1)4PDF(0.0118mgBHP-h), respectively (Figs. 2C, D).However, it should be noted that EFtotal-PAHs andEFtotal-BaPeq in mgL�1-fuel (or mgBHP�1-h�1) forFBFO was 3.41-fold (or 3.35-fold) and 5.82-fold (or5.69-fold) higher than those for PDF.

The emission factor of PAHs (mgg�1) from thediesel exhaust normalized by the mass of total-polyaromatics in the fuels (mgg�1) was estimated by thePAH emission factor (mgL�1-fuel), the density offuels and the total-poly aromatic contents in the fuel.For FBFO, the EFtotal-PAH and EFtotal-BaPeq in mgg�1

of total-poly aromatics were 0.87 and 0.0040mgg�1,respectively, and 1.07 and 0.0027mgg�1 for PDF,respectively. We found that there were more high-molecular-weight aromatic contents in FBFO thanthat in PDF. Therefore, it could be expected that morehigh-molecular-weight PAHs would be emitted fromFBFO rather than PDF. On the other hand, it alsocould be expected that more low-molecular-weightPAHs would be emitted from PDF rather than FBFOsince the more complete combustion was known forthe former. Since PAHs with the higher molecularweight are known with the higher carcinogenicpotencies, which explains why higher EFtotal-BaPeq

were found in FBFO but higher EFtotal-PAH in PDF.Our results also suggest that total-PAH (summationof 21 individual PAHs) and total-BaPeq emissionsfrom the diesel engine exhaust can be predicted byusing the total-poly aromatic contents in the fuels.

3.5. Impacts on PAH emissions due to the illegal use

of FBFO by TDV

Table 4 shows the amount of total-PAH emissionfrom mobile sources in Taiwan during 2003 wasestimated as 18.4, 8.41, 21.5 and 83.8 metric tonsfrom two-stroke motorcycles, four-stroke motor-cycles, gasoline-fueled cars and diesel-engine vehi-cles, respectively; they were equal to 13.9%, 6.37%,21.5% and 63.5% of total-PAH emissions frommobile sources in Taiwan. The amount of total-BaPeq emission were 0.0390, 0.0331, 0.145 and 0.287metric tons from two-stroke motorcycles, four-stroke motorcycles, gasoline-fuel cars and diesel-engine vehicles, respectively; they were equal to7.74%, 6.57%, 28.8% and 56.9% of total-BaPeq

emissions from mobile sources in Taiwan.The diesel fuel consumption of diesel-engine

vehicles in 2003 in Taiwan was estimated at

ARTICLE IN PRESS

Table 4

Amount of total-PAH and total-BaPeq emissions from mobile sources during 2003 in Taiwan

Mobile sources Numbers of

vehicles during

year 2003 in

Taiwan

Estimated

volume of fuel

consumption

during 2003 in

Taiwan (kL)

EFtotal-PAHs

(mgkL�1)

EFtotal-BaPeq

(mg kL�1)

Amount of

total-PAH

emission during

2003 (metric

tons)

Amount of

total-BaPeq

emission during

2003 (metric

tons)

Two-stroke

motorcycles

5,180,613 924,554 19,900b 42.2b 18.4 (13.9%) 0.0390 (7.74%)

Four-stroke

motorcycles

7,418,711 1,605,759 5240b 20.6b 8.41 (6.37%) 0.0331 (6.57%)

Gasoline-fueled cars 6,063,602 7,861,715 2730b 18.5b 21.5 (16.3%) 0.145 (28.8%)

Diesel-engine vehicles 184,891 3,984,671a 15,100 (PDF) 40.4 (PDF) 83.8 (63.5%) 0.287 (56.9%)

Total 18,900,105 14,376,699 — — 132 (100%) 0.504 (100%)

aIncluding 3,334,671 kL of PDF legally used and 650,000 kL of FBFO used illegally by diesel-engine vehicles.bData obtained from our research group.

Y.-C. Lin et al. / Atmospheric Environment 40 (2006) 1601–16091608

3,984,671kL, this figure included 3,334,671kL ofPDF legally used and 650,000kL of FBFO usedillegally by TDVs, which accounted for approximately16.3% of total diesel fuel consumed by TDVs. If the650,000kL of FBFO was replaced with legal dieselfuel (i.e., PDF), the amount of total-PAH and total-BaPeq emissions from diesel-engine vehicles in 2003 inTaiwan would be 60.2 and 0.161 metric tons,respectively. Therefore, the emission increase fortotal-PAHs and total-BaPeq in 2003 in Taiwan fromTDVs illegally burning FBFO was 23.6 and 0.126metric tons, and resulted in a 17.9% and a 25.0%increase in total-PAHs and total-BaPeq from mobilesources, respectively, or a 39.2% and a 78.3% increasefor diesel-engine vehicles, respectively. Analysis ofthese results confirmed that the TDVs illegallyburning FBFO had a significant impact on the PAHemissions from mobile sources. There are somestrategies for the prevention of FBFO from beingused illegally in TDVs, such as lowering the subsidy ofFBFO, increasing frequencies for on-road pollutantinspection particularly for TDVs driving in the harborareas, and issuing more rigorous punishment, etc.

4. Conclusion

This study shows that the emission factor of PMin the exhaust of HDDE burning FBFO was0.296 gBHP-h, 3.15 times higher than HDDEburning PDF. But there was no significant differencein emissions of CO, CO2 or NOx for FBFO andPDF. For PAHs, the magnitudes of EFtotal-PAHs andEFtotal-BaPeq in mgL�1-fuel were FBFO(51.5mgL�1-fuel)4PDF (15.8mgL�1-fuel) andFBFO (0.235mgL�1-fuel)4PDF (0.0404mgL�1-

fuel), respectively. The above result confirmed thatTDVs using FBFO with a high poly aromaticcontent discharged considerable amount of hazar-dous PAHs into the ambient air. The emissionincrease of total-PAHs and total-BaPeq in 2003 inTaiwan arising from the illegal use of FBFO byTDVs were 23.6 and 0.126 metric tons, whichresulted in a 17.9% and a 25.0% increase frommobile sources, respectively, or a 39.2% and a 78.3%increase for diesel-engine vehicles, respectively. Theseresults proved that TDVs illegally using FBFO had asignificant impact on total amount of PAH emissionsfrom mobile sources and hence need our greatattention on it.

Acknowledgments

The authors gratefully acknowledge the contribu-tions of Mr. S.H. Gua, Refining and ManufacturingResearch Center, Chinese Petroleum Corporation,for heavy-duty diesel engine operation and Mr. S.K.Lien, Department of Environmental Engineering,National Cheng Kung University, for helping thelaboratory work.

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