DSpace at VNU: Distribution of persistent organic pollutants and polycyclic aromatic hydrocarbons in sediment samples from Vietnam

DSpace at VNU: Distribution of persistent organic pollutants and polycyclic aromatic hydrocarbons in sediment samples fr...

Distribution of Persistent Organic Pollutants and Polycyclic Aromatic Hydrocarbons in Sediment Samples from Vietnam

Masao Kishida,∗, aKiyoshi Imamura,a Yasuaki Maeda,b Tran Thi Ngoc Lan,c

Nguyen Thi Phuong Thao,d and Pham Hung Viete

a Environmental Pollution Control Center, Osaka Prefectural Government, 1–3–62 Nakamichi, Higashinari-ku, Osaka 537–0025, Japan, b Graduate School of Engineering, Osaka Prefecture University, 1–1 Gakuen-cho, Naka-ku, Sakai, Osaka 599–8531, Japan,

c College of Natural Science, Vietnam National University of Ho Chi Minh City, 227 Nguyen Van Cu Str., Dist.5, Ho Chi Minh City, Vietnam, d National Center for Natural Science and Technology, Hoang Quoc Viet Str., Hghia Do, Cau Giay, Hanoi, Vietnam, and

e College of Science, Vietnam National University of Hanoi, T3 Building, 333 Nguyen Trai Str., Thanh Xuan Dist., Hanoi, Vietnam

(Received January 11, 2007; Accepted April 2, 2007; Published online April 6, 2007)

The presence of eight kinds of persistent organic pollutants (POPs) such as DDT and its metabolites (DDTs), hexachlorocyclohexanes (HCHs), chlordane compounds (CHLs), drin compounds (Drins), heptachlor, hexachlorobenzene (HCB), heptachlor-epoxide, polychlorinated biphenyls (PCBs) and sixty-four polycyclic aro-matic hydrocarbon compounds (PAHs) was identified using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) to investigate their distribution in surface sediment from Hanoi, Hue, and Ho Chi Minh in Vietnam A survey of sediment samples from Osaka was conducted for comparison The concentra-tions of ΣDDTs, ΣCHLs, ΣPCBs and ΣPAHs in Vietnam were 0.19–140, N.D.–9.0, 0.11–110, and 30–5500 ng/g-dry, respectively Concentrations of these compounds in urban areas were higher than those in other areas In addition, the ΣDDT concentrations in Vietnamese urban areas were higher than those in Osaka These results sug-gest that most DDTs would be used as insecticides for the purpose of health services rather than as agricultural chemicals PAH pollution in urban areas and suburbs is caused mainly by runoff of petrol, whereas in rural areas, the combustion of fossil fuels and biomass is the major pollutant source.

Key words —— persistent organic pollutant, polycyclic aromatic hydrocarbon, Vietnam, sediment sample, high

resolution gas chromatography/high resolution mass spectrometry

INTRODUCTION

More than 120 countries participated in the

May 2001 Stockholm Convention on persistent

organic pollutants (POPs), adopting the

reduc-tion and/or prohibireduc-tion of their use The

con-vention identified twelve types of compounds as

POPs, which consist of intentional compounds and

unintentional by-products of industrial processes

The former are DDT and its metabolites (DDTs),

hexachlorocyclohexanes (HCHs), chlordane

com-pounds (CHLs), toxaphene, drin compounds

(Drins), hexachlorobenzene (HCB),

polychlori-nated biphenyls (PCBs), and mirex; and the

lat-ter are polychlorinated dibenzo- p-dioxins (PCDDs)

∗

To whom correspondence should be addressed:

Environ-mental Pollution Control Center, Osaka Prefectural

Govern-ment, 1–3–62 Nakamichi, Higashinari-ku, Osaka 537–0025,

Japan Tel.: +81-6-6972-1321; Fax: +81-6-6972-5865; E-mail:

KishidaMas@mbox.pref.osaka.lg.jp

and polychlorinated dibenzofurans (PCDFs) The issue of POPs has generated a lot of inter-est in most countries POPs released to the envi-ronment can be transported through air and water to regions far from their original sources, such as the Arctic.1)Moreover, POPs bioaccumulate in fatty tis-sues of living organisms because of low water solu-bility and/or high fat solusolu-bility

In Southeast Asia and South Asia, a great deal

of POPs have been used since the 1960s.2, 3) Ap-proximately 24000 tons of DDTs were imported to Vietnam between 1957 and 1990 to control malaria vectors and to remove insect pests from grains.4) Al-though the use of these pesticides has been prohib-ited since 1993, and the quantity of imported pesti-cides has been reduced, organochlorine pestipesti-cides still remain in the environment of northern Viet-nam.5, 6)

Import of approximately 27000–30000 tons of oil containing PCBs from socialist countries such

as the U.S.S.R., China, and Romania,4) and a great

deal of electric products from Australia has

con-tributed to the presence of PCBs.7)

Polycyclic aromatic hydrocarbons (PAHs) are

considered serious pollutants because of their

car-cinogenicity The two main origins of PAH

pol-lution are petroleum runoff and the combustion of

fossil fuel and biomass.8) Concentrations of PAHs

in industrialized cities such as Boston9, 10)and New

York11) were extremely high and are thought to

result from petroleum use In contrast, in

devel-oping countries such as Malaysia, their

concentra-tions were not as high, and their primary origin was

supposed to be the combustion of fossil fuel and

biomass.8)

Since 1986, the economy of Vietnam has been

rapidly expanding due to Doi Moi policy, which

in-troduced a free market economy system to the

so-cialist country The country has been industrialized,

and the number of motorcycles in the cities has

dras-tically increased As a result, the consumption of

petrol has increased in cities such as Hanoi and Ho

Chi Minh

Several POP surveys have been conducted in

ur-ban areas3, 6, 12) using gas chromatography/electron

captured detectors (GC/ECD) However, detailed

investigations of their components, such as the

geners and/or isomers of PCBs, have not been

con-ducted

In the present study, we determined the

concen-trations of POPs and PAHs in sediment samples

us-ing high resolution gas chromatography/high

rolution mass spectrometry (HRGC/HRMS) to

es-timate their distribution throughout Vietnam The

sampling locations were 2 sites in Hanoi, 4 sites in

Hue, 5 sites in Ho Chi Minh, and 1 site in Osaka,

Japan, situated at the mouth of the Yamato River

POP monitoring has been conducted at the latter

sampling site since 1978, to determine the

effec-tiveness of the Chemical Substances Control Law

in Japan, which has prohibited their production and

use since 1972

MATERIALS AND METHODS

Compounds Examined —— The POPs monitored

were DDTs (o, p′

-, p, p′

-DDT, o, p′

-, p, p′

-DDD,

and o, p′

-, p, p′

-DDE), HCHs (α-, β-, γ-, δ-HCH),

CHLs (trans-, cis-chlordane, trans-, cis-nonachlor,

and oxchlordane), Drins (aldrin, dieldrin, and

en-drin), heptachlor, heptachlor-epoxide, HCB, and

PCBs

PAHs are classified into six categories, depend-ing on the number of rdepend-ings in the molecule;

2-ring: naphthalene, benzo[b]thiophene,

1-,2-methylnaphthalene, biphenyl, 2,6-, 2,7-, 1,3-, 1,4-, 2,3-, 1,5-, 1,2-dimethylnaphthalene, and 2,3,5-trimethylnaphthalene;

3-ring: acenaphthylene, biphenylene, aceneph-thene, fluorene, 9,10-dihydroanthracene, 9,10-dihydrophenanthrene, dibenzothiophene,

phenan-threne, anthracene, 1-,2-phenylnaphthalene, o-, m-,

p-terphenyl, 1-, 2-, 3-, 4-, 9-methylphenanthrene, 2-,9-methylanthracene, 3,6-dimethylphenanthrene, and 9,10-dimethylanthracene;

4-ring: 1,2,3,4-tetrahydrofluoranthene,

4H-cyclopenta[def ]phenanthrene (4H-CdefP), pyrene,

fluoranthene, benzo[b]fluorene, 1,1-binaphthyl, 9-phenyanthracene, benz[a]anthrathene (BaA), triphenylene, chrysene, naphthacene, and

7-methylbenz[a]anthracene (7-MeBaA);

5-ring: benzo[b]fluoranthene (BbF), benzo[ j] fluoranthene (BjF), benzo[k]fluoranthene (BkF), benzo[e]pyrene (BeP), benzo[a]pyrene (BaP),

perylene, 3-methylcholanthrene, 7-methylbenzo[a]

pyrene (7-MeBaP), 9,10-diphenylanthracene, and

dibenzo[a, h]anthracene;

6-ring: indeno[1,2,3-cd]pyrene (INcdP), benzo [ghi]perylene (BghiP), anthanthrene,

naphtho[2,3-a]pyrene, and 3,4,8,9-dibenzopyrene;

7-ring: coronene

Sampling Methods —— The sample properties

and sampling locations are shown in Table 1 Sed-iments were collected at three points near the sam-pling site using an Eckmann dredge samsam-pling ap-paratus The sediments were mixed uniformly and put in a glass vessel for transport to the laboratory The sediments were centrifuged by 3000 rpm for

10 min to remove water, and stored in the refrig-erator Some samples were dried under moderate conditions in the laboratory

Reagents —— Standard POP materials except for

p, p′

-DDE, CHLs, and PCBs were purchased from Gasukuro Kogyo Inc (Tokyo, Japan) A standard

material of p, p′

-DDE was purchased from Wako Pure Chemical Industries Ltd (Osaka, Japan) Stan-dard solutions of CHLs were purchased from Ac-cuStandard Inc (Shelton, CT, U.S.A.) A stan-dard mixture solution of PCBs (BP-WD) was pur-chased from Wellington Laboratories, Inc (Ontario, Canada) A standard mixture solution of 16 PAH components (TCL Polynuclear Aromatic Hydrocar-bons Mix) cited in Target Compound List/Priority

Table 1 List of Sediment Samples from Vietnam

02 ′

46 ′′

101 ◦

50 ′

21 ′′

27/July/2002

03 ′

27 ′′

105 ◦

50 ′

15 ′′

27/July/2002

33 ′

37 ′′

107 ◦

37 ′

15 ′′

13/January/2002

29 ′

30 ′′

107 ◦

43 ′

20 ′′

12/January/2002

20 ′

19 ′′

107 ◦

52 ′

28 ′′

10/January/2002

23 ′

31 ′′

107 ◦

34 ′

35 ′′

10-12/January/2002

45 ′

48 ′′

106 ◦

41 ′

54 ′′

18/July/2002

49 ′

08 ′′

106 ◦

43 ′

55 ′′

16/July/2002

47 ′

36 ′′

106 ◦

41 ′

46 ′′

16/July/2002

48 ′

52 ′′

106 ◦

45 ′

07 ′′

16-18/July/2002

51 ′

04 ′′

106 ◦

43 ′

44 ′′

16-18/July/2002

36 ′

30 ′′

135 ◦

26 ′

06 ′′

11/October/2002

a) Japan.

Table 2 Operational Conditions for HRGC/HRMS

HRGC

30 m × 0.25 mm I.D., 0.5 µm f.t 15 m × 0.25 mm I.D., 0.25 µm f.t.

C (1 min.hold)–30 ◦

C/min–160 ◦

C (1 min.hold)–15 ◦

C/min–130 ◦

C–

5 ◦ C/min–300 ◦

C/min–300 ◦

C (2 min.hold)

C

HRMS

C

C

Pollutant List of US EPA was purchased from

Supelco (Bellefonte, PA, U.S.A.) Standard

so-lutions of methylphenanthlene isomers were

pur-chased from Chiron AS (Trondheim, Norway)

Standard solutions of 2-phenylnaphthalene,

3,6-dimethylphenanthrene, 7-MeBaA, BeP, and

an-thanthrene were purchased from AccuStandard Inc

All other PAH materials were purchased from Wako

Pure Chemical Industries Ltd., AccuStandard Inc.,

Supelco, Aldrich Chemical Co., Inc (Milwaukee,

WI, U.S.A.), Tokyo Kasei Kogyo Co., Ltd (Tokyo,

Japan), Ishizu Pharmaceutical Co., Ltd (Osaka,

Japan), Nakarai Chemicals Ltd (Kyoto, Japan),

ICN Biomedicals Inc (Aurora, OH, U.S.A.), Acros

Organics (Morris Plains, NJ, U.S.A.), and Alfa

Ae-sar (Ward Hill, MA, U.S.A.) A standard

mate-rial of fluoranthene-d12 was purchased from Wako

Pure Chemical Industries Ltd All other reagents were purchased from Wako Pure Chemical Indus-tries Ltd All chemicals were residual pesticide an-alytical grade

Analysis —— Sample extraction and clean-up

fol-lowed procedures specified in the manual edited

by the Ministry of the Environment, Japan.13) Ten-twenty g of wet and/or dry sediment was extracted three times with 25 ml acetonitrile using ultrasonic extraction The extracts were cleaned up with

the acetonitrile/n-hexane partition The acetonitrile

layer was put into 500 ml of 5% sodium chloride

so-lution and extracted twice with 50 ml n-hexane The

concentrate was cleaned up with 5 g of 5% hydrous silica gel column chromatography The first

frac-tion, eluted with 20 ml of n-hexane, was treated with

5 g reduced granular copper (60–80 mesh) The

sec-Fig 1 Representative SIM Chromatograms of POPs (DDTs and PCBs) at the Sampling Site of HC3

(A) and (B): DDTs, (C): PeCBs.

ond fraction, eluted with 50 ml of 1%

acetone/n-hexane, was submitted for PAHs analysis The third

fraction was eluted with 40 ml of 10%

acetone/n-hexane 100 ng of fluoranthene-d12 was added to

each fraction and submitted for analysis One µl

of each concentrate was analyzed by HRGC/HRMS

(HP5890; Agilent, DE, U.S.A JMS-700D; JEOL,

Japan) and the conditions are shown in Table 2

Representative chromatograms of selected ion

mon-itoring (SIM) for a sediment sample at a location

HC3 were shown in Fig 1

RESULTS AND DISCUSSION

POPs

Analytical results for DDTs are shown in Ta-ble 3 The averages of ΣDDTs for Hanoi, Hue, Ho Chi Minh, and Osaka were 43, 1.3, 36, and 13 ng/g-dry, respectively The ΣDDT concentrations at sam-pling sites HN1, HN2, HC1, and HC3, located in urban areas, range between 29 and 140 ng/g-dry, while concentrations at the other sites in Vietnam range between 0.19 and 5.5 ng/g-dry These data

Table 3 Concentrations of POPs (ng/g-dry weight) in Sediment Samples from Vietnam and Osaka

Sampling locations

p, p′

p, p′

p, p′

o, p′

o, p′

o, p′

γ-HCH 0.14 0.074 0.12 0.033 N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) 0.056 N.D.e) N.D.e) δ-HCH 0.077 0.081 0.055 0.023 N.D.e) N.D.e) N.D.e) N.D.e) 0.040 N.D.e) N.D.e) 0.090

trans-Chlordane 0.54 0.034 0.010 0.007 0.016 N.D.e) 0.37 0.014 3.1 0.084 N.D 7.6

cis-Chlordane 0.29 N.D.e) 0.013 N.D.e) N.D.e) N.D.e) 0.34 0.014 2.9 N.D.e) N.D.e) 7.2 Oxychlordane N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e)

trans-Nonachlor 0.20 N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) 0.20 N.D.e) 2.1 0.064 N.D.e) 6.1

cis-Nonachlor 0.042 N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) 0.15 N.D.e) 0.80 0.036 N.D.e) 2.6

Aldrin N.D.e) 0.008 N.D.e) 0.054 N.D.e) N.D.e) N.D.e) 0.012 0.095 N.D.e) N.D.e) 0.054 Dieldrin 0.65 N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) 5.9 N.D.e) 6.2 N.D.e) N.D.e) 0.54 Endrin N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) 0.10 Σdrinsd) 0.65 0.008 N.D.e) 0.054 N.D.e) N.D.e) 5.9 0.012 6.3 N.D.e) N.D.e) 0.70 Heptachlor 0.96 N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) 0.41

Heptachlor Epoxide N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) N.D.e) 0.066 N.D.e) N.D.e) N.D.e)

a ) Sum of concentratios of o, p′-, p, p′-DDT, o, p′-, p, p′-DDD, and o, p′-, p, p′-DDE b) Sum of concentrations of α-, β-, γ-, δ-HCH c) Sum of concentrations of trans-, cis-chlordane, trans-, cis-nonachlor, and oxchlordane d) Sum of concentrations of aldrin, dieldrin, and endrin.

e) N.D., not detected.

show that the ΣDDT concentrations in urban areas

of Hanoi and Ho Chi Minh were higher than those

in Osaka

In an aqueous environment, p, p′

-DDT

decom-poses very slowly to p, p′

-DDE and subsequently

to p, p′

-DDD through biological and chemical

pro-cesses.14)The residence time of p, p′

-DDT could be

estimated using the ratio of p, p′

-DDT to ΣDDTs

The ratio for technical DDTs was reported to be

0.77.15)Ratios of p, p′

-DDT to ΣDDTs at sampling sites HU1, HU2, HU3, HU4, and HC5 were 0.22–

0.33, and those at the other locations were 0.02–

0.13 These results indicate that fields in areas HU1,

HU2, HU3, HU4, and HC5 have been sprayed with

DDTs more recently

Analytical results for HCHs are also shown in

Table 3 The averages of ΣHCHs for Hanoi, Hue,

Ho Chi Minh, and Osaka were 0.54, 0.13, 0.085,

and 0.61 ng/g-dry, respectively ΣHCH

concentra-tions in the sediment samples were lower than those

of ΣDDTs, despite the fact that HCHs were used in Vietnam as well as DDTs.16) Nhan et al.6) pointed out that lower concentrations of ΣHCH, compared with ΣDDT, are caused by the relatively short envi-ronmental half-lives of HCHs in soils (T1/2of hours

to weeks), lower K OW 3.6–3.8, and higher water solubilities, which are 3 to 4 orders of magnitude higher than those of DDTs In addition, the ΣHCH and ΣDDT concentrations in the atmospheric en-vironment at Hue were reported to be 12000 and

2400 ng/m3, respectively.2) These results indicate that HCHs are more volatile than DDTs, and evap-orate readily into the atmosphere

Previously, the technical HCH mixtures have been reported17) to contain 55–80% of α-HCH, 5– 14% of β-HCH, and 8–15% of γ-HCH, and the ratio

of α-/γ-HCH was 5.3–6.7 The ratios of α-/γ-HCH

at sampling sites HN1, HN2, HU1, HU2, and HC4 were 0.58–2.2, lower than those of technical HCH These results indicate that the HCHs used in

Viet-nam contained higher percentages of γ-HCH, that

is, Linden.18)

Analytical results for CHLs are also shown in

Table 3 The ranges of ΣCHL concentrations in

Hanoi, Hue, Ho Chi Minh, and Osaka were 0.034–

1.1, N.D.–0.023, N.D.–9.0, and 24 ng/g-dry,

respec-tively The ΣCHL concentrations at urban areas

ex-cept for a sampling site NH2 were 1.1–24 ng/g-dry

and those at the other sites were N.D.–0.18 ng/g-dry

These results indicate that the ΣCHL concentrations

in Osaka were higher than those at the urban areas

of Vietnam No oxychlordane compounds were

de-tected in the sediments

Iwata et al.3) reported that the technical CHLs

consist of 24±2 wt% of trans-chlordane, 19±3%

of cis-chlordane, 7±3% of trans-nonachlor, and

other compounds, and the ratios of trans-nonachlor

to trans-chlordane ranged between 0.15–0.45,

un-der continuous CHL usage The ratios of

trans-nonachlor to trans-chlordane at HN1, HC1, HC3,

and Y1 were 0.37, 0.54, 0.68, and 0.80,

respec-tively The value at HN1 was close to those of

tech-nical chlordane In contrast, the ratios at HC1, HC3,

and Y1 were higher than those of technical CHLs

In Japan, CHLs remaining in the environment have

resided for more than 30 years, since the production

and use of POPs was prohibited in 1972 Over a

long residence time, the ratio of trans-nonachlor to

trans-chlordane changes due to the preferential

de-pletion of trans-chlordane.3, 19, 20)

Analytical results for Drins, HCB, heptachlor,

and heptachlor-epoxide are also shown in Table 3

The concentration ranges of aldrin, dieldrin, endrin,

heptachlor, HCB, and heptachlor-epoxide in Hanoi,

Hue, Ho Chi Minh, and Osaka were N.D.–0.96,

N.D.–0.054, N.D.–16, and N.D.–0.70 ng/g-dry,

re-Table 4 Concentrations of PCBs Congeners (ng/g-dry weight) in Sediment Samples from Vietnam and Osaka

Sampling locations

MoCBs N.D.b) N.D.b) N.D.b) N.D.b) N.D.b) N.D.b) N.D.b) N.D.b) 0.11 0.12 N.D.b) 0.16

OcCBs 0.17 N.D.b) N.D.b) N.D.b) N.D.b) N.D.b) 0.79 0.21 2.6 0.22 N.D.b) 0.35 NoCBs N.D.b) N.D.b) N.D.b) N.D.b) N.D.b) N.D.b) 0.12 N.D.b) 0.36 N.D.b) N.D.b) N.D.b) DeCBs 0.14 N.D.b) N.D.b) N.D.b) N.D.b) N.D.b) 0.43 N.D.b) 1.7 N.D.b) N.D.b) 0.073

a ) Sum of concentrations of Mo to DeCBs b) N.D., not detected.

spectively The concentrations of these compounds were low when compared with DDTs and CHLs Analytical results for PCBs are shown in Ta-ble 4 The averages of ΣPCBs in Hanoi, Hue,

Ho Chi Minh, and Osaka were 21, 0.46, 33, and

67 ng/g-dry, respectively The ΣPCBs concentra-tions at sampling sites HN1, HN2, HC1, HC3, and Y1 were 21–110 ng/g-dry and those at the other sites were 0.11–7.3 ng/g-dry These data show that the concentrations of ΣPCBs in urban areas of Hanoi and Ho Chi Minh were at the same levels as those in Osaka

Profiles of PCB congeners at the five sampling sites NH1, HN2, HC1, HC3, and Y1 and for the commercial product Kanechlor (KC)21) are shown

in Fig 2 The pentachloro-biphenyls (PeCBs) were the highest congeners at sampling sites HN1 and HN2 and the trichloro-biphenyls (TriCBs) were the highest ones at sampling sites HC1 and HC3 These facts indicate that the PCB components in Hanoi (at sampling sites HN1 and HN2) was mainly con-tributed from the KC-500 product and Ho Chi Minh (at sampling sites HC1 and HC3) were from the

KC-300 product At the site of Y1, the concentrations of PCB congeners increased as the number of the chlo-rine atoms in the PCB molecules decreased The dichloro-biphenyls (DiCBs) was the highest con-geners However, DiCBs was not main compo-nents of any PCB products These facts suggest that the higher chlorinated PCBs would be dechlorinated gradually to the lower ones under anaerobic con-ditions22, 23) as shown in the Netherlands24) and in Rhode Island, U.S.A.25)

As discussed previously, ΣDDTs, ΣCHLs, and ΣPCBs at sampling sites HN1, HN2, HC1, HC3, and Y1, located near the center of cities, were much

Fig 2 Homologue Profiles of PCBs in Sediment Samples from Vietnam and Osaka

Relative concentration was the ratio of each PCBs homologue to the most intense one (A) HN1, (B) HN2, (C) HC1, (D) HC3, (E) Y1, (F) KC-300, (G) KC-400, (H) KC-500, (I) KC-600.

higher than those at the other sites The ΣDDT

con-centrations in Vietnamese urban areas were higher

than those in Osaka These facts suggest that they

were mainly used as insecticides for public health

reasons rather than as agricultural chemicals In

contrast, the ΣCHL concentrations in Osaka were

higher than those in Vietnamese urban areas The

CHLs have been stored in sediment of Osaka for

more than 30 years because of long environmental

half-lives and the moderate climate of Japan The

use and production of CHLs have been prohibited since 1972 by the law in Japan,

PAHs

Analytical results for PAHs are shown in Ta-ble 5 The averages of ΣPAHs in Hanoi, Hue,

Ho Chi Minh, and Osaka were 1600, 130, 1900, and 3200 ng/g-dry, respectively The concentra-tions of ΣPAHs at sampling sites HN1, HN2, HC1, HC3, and Y1, which were located in urban areas,

Table 5 Concentrations of PAHs (ng/g-dry weight) in Sediment Samples from Vietman and Osaka

Sampling locations

1,2,3,4-tetrahydrofluoranthene 0.5 0.4 N.D.i) N.D.i) N.D.i) N.D.i) 2.0 0.2 2.9 0.5 N.D.i) 0.9

9,10-diphenylanthracene 1.9 N.D.i) N.D.i) N.D.i) N.D.i) N.D.i) 0.3 N.D.i) N.D.i) N.D.i) N.D.i) N.D.i)

3,4,8,9-dibenzopyrene N.D.i) N.D.i) N.D.i) N.D.i) N.D.i) N.D.i) N.D.i) N.D.i) N.D.i) N.D.i) N.D.i) N.D.i)

a ) Sum of 2-ring PAH compound concentrations b) Sum of 3-ring PAH compound concentrations c) Sum of 4-ring PAH compound concentrations d) Sum of 5-ring PAH compound concentrations e) Estimated by subtracting the concentration of perylene from ΣPAHs f ) Sum

of 6-ring PAH compound concentrations g) Coronene concentration h) Sum of 2- through 7-ring PAH compound concentrations i) N.D., not

detected.

were 1700–5700 ng/g-dry, while those at other sites

were 30–420 ng/g-dry These values were estimated

by subtracting the concentration of perylene from

ΣPAHs since perylene is considered to be naturally

occurring.26) The ΣPAHs concentrations in urban

areas of Hanoi and Ho Chi Minh were at the same levels as in Osaka

The profiles of 2- to 7-aromatic ring PAHs at HN1, HN2, HC1, HC3, and Y1 are shown in Fig 3 The compositions of the 2- to 7-ring PAHs at the five

Fig 3 Profiles of 2- to 7-Aromatic Rings of PAHs in Sediment Samples from Vietnam and Osaka

locations HN1, HN2, HC1, HC3, and Y1 were

sim-ilar to each other The percentages of 2-, 3-, 4-, 5-,

6-, and 7-ring PAHs to ΣPAHs at the five locations

listed above were 1–6%, 7–14%, 17–32%, 31–38%,

22–31%, and 2–5%, respectively Thus, the

sedi-mentary PAHs at these locations mainly consist of

4- to 6-ring PAHs

The predominant components observed at

sam-pling sites NH1 and HN2 were BaP, BghiP, pyrene,

INcdP, BeP, BaA, BbF/BjF, and BkF and their

av-erages were 220, 210, 190, 120, 120, 87, 72, and

69 ng/g-dry, respectively At HC1 and HC3, the

predominant components were BaP, BghiP, INcdP,

BeP, methylphenanthrene isomers, BaA, pyrene,

BkF, and BbF/BjF and their means were 740, 550,

350, 240, 240, 220, 200, 150, and 120 ng/g-dry,

respectively At Y1, the predominant components

were BaP, BghiP, INcdP, pyrene, BeP, BkF, and

BbF/BjF and their concentrations were 580, 450,

300, 250, 240, 160, and 150 ng/g-dry, respectively

Profiles of predominant PAH components at

HN1, HN2, HC1, HC3, and Y1 are shown in Fig 4

The two components, BaP and BghiP among eleven

predominant ones were mainly observed at the five

sampling sites The PAH components in the

re-gional differences were pyrene and

methylphenan-threne isomers The concentrations of pyrene were

relatively high in Hanoi and Osaka, and those of

methylphenanthrene isomers in Ho Chi Minh

Zakaria et al.8)reported that the origin of PAHs

could be estimated using the ratio of total

concentra-tions of methylphenanthrene isomers (ΣMPs) to that

of phenanthrene (P) The ratios in petrol were more

than 2.0, whereas those emitted by combustion of

Table 6 ΣMPsa) /Pb) Ratios in Sediment Samples from

Vietnam and Osaka

a) Sum of concentrations of 1-, 2-, 3-, 4-,

9-methylphenanthrene b) concentration of phenanthrene.

the materials were less than 1.0 because phenan-threne was a predominant compound produced in the combustion process The ratios of ΣMPs/P are shown in Table 6 The ratios at sampling locations HN1, HN2, HC1, HC2, HC3, HC4, and Y1 were 1.9–4.9 These values show that PAH pollution at these sites was mainly caused by petrol runoff (pet-rogenic origin) In contrast, ΣMPs/P at other loca-tions were 0.7–1.1 The PAH pollution at these lo-cations was of pyrogenic origin

The higher values of ΣPAHs were observed in urban areas, as in the case of POPs The PAHs in the urban areas and suburbs are predominantly of peterogenic origin, whereas in the rural areas, the PAHs are of pyrogenic origin, such as the combus-tion of fossil fuel and biomass

Fig 4 Profiles of Predominant PAH Components in Sediment Samples from Vietnam and Osaka

Relative concentration was the ratio of each PAH component to the BaP (A) HN1, (B) HN2, (C) HC1, (D) HC3, (E) Y1 a: phenanthrene, b: ΣMPs, c: fluoranthene, d: pyrene, e: BaA, f: BbF/BjF, g: BkF, h: BeP, i: BaP, j: INcdP, k: BghiP.

Acknowledgements We heartily express our

thanks to Prof Jyunko Oda, Kibi Kokusai

Univer-sity, for technical support of GC/MS analysis of

PAHs and also to Dr Norimichi Takenaka, Osaka

Prefecture University, for useful advice

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