Chlorinated organic compounds in urban air in Japan

The Science of the Total Environment, 74 (1988) 121 131 Elsevier Science Publishers B.V., A m s t e r d a m Printed in The Netherlands

121

C H L O R I N A T E D ORGANIC C O M P O U N D S IN U R B A N AIR IN J A P A N

KOHEI URANO, KATSUYA KAWAMOTO, YOSHIHUMI ABE and MASATOSHI OTAKE

Yokohama National University, 156 Tokiwadai, Hodogaya-ku, Yokohama-city, 240 (Japan) (Received November 17th, 1987; accepted J a n u a r y 1st, 1988)

ABSTRACT Air pollution by the principal chlorinated organic compounds chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene and tetrachloroethylene was investigated over a period of ~ 1 year at 15 sites in an u r b a n area. Each compound was detected in the range from ~ 0.1 to several ppb; the concentrations of these compounds, with the exception of carbon tetrachloride, were higher t h a n their global pollution levels. The c o n c e n t r a t i o n s of 1,1,1-trichloroethane and trichloroethylene especially were very h i g h in the industrial regions, and the c o n c e n t r a t i o n of tetrachloroethylene was very high in the industrial and commercial regions. Concentrations were low in spring and s u m m e r and h i g h in fall, winter and the rainy season. The correlation between the reciprocal of wind speed and concentrations was found to be subject to seasonal variations. Intake of chlorinated organic compounds by m a n from the air was estimated from the data to be larger t h a n the allowable intakes determined by WHO and EPA for drinking water.

INTRODUCTION

Chlorinated organic compounds are widely used as raw materials for the production of chemicals and solvents and for washing metal parts and clothing (Urano, 1985). Pollution of groundwater by these compounds has attracted much attention because of their carcinogenicity and mutagenicity; regulatory levels for drinking water have been established (EPA, 1976; WHO, 1987). However, many of these materials are discharged into the atmosphere, therefore it is necessary to ascertain the distribution of such compounds in the air in order to estimate their influence on man. There have been a few investigations of global pollution levels (Rasmussen and Khalil, 1982; Kirschmer and Ballschmiter, 1983; Class and Ballschmiter, 1986; Makide et al., 1987) and of the concentrations in urban air over a short period of time (Ohta et al., 1976; Singh et al., 1982; Bozzelli and Kebbekus, 1982; Harkov et al., 1983), but long-term investigations of air pollution in urban areas have been very scarce up till now. One reason for this is that chlorinated organic compounds have not caused much concern as important air pollutants. Another is that there have been many problems with methods of measurements (Kawamoto and Urano, 1986). Since pollutants were collected over a short period of time and analyzed by conventional methods, the data obtained only gave momentary concentrations which fluctuated frequently with weather conditions. Air pollution by these chlorinated organic compounds should be investigated over the long

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122

term because of their potential carcinogenicity; it is important to obtain mean concentrations and total exposure over a prolonged period of time. In order to determine long-term pollution levels at a particular site by conventional methods, concentrations must be measured many times. For example, samples must be collected and analyzed using an automatic analyzer once or twice an hour. As reported previously (Kawamoto and Urano, 1987), a convenient sampling method has been developed to determine mean concentrations of chlorinated organic compounds over a 1 or 2-week period. In the present study, the concentrations of the principal volatile chlorinated organic compounds in the air were measured by this new method at 15 sites in three cities in Japan for ~ 1 year and intake by man of these compounds was estimated. MATERIALS AND METHODS

Activated carbon and solvent A granular activated carbon, BPL (Calgon Co., U.S.A.), was selected for sampling chlorinated organic compounds from the air. The activated carbon was ground, sieved through a 30-60 mesh, washed with distilled water and dried. It was then packed into a glass column and purified for 4 h at 110°C under a nitrogen flow of 700 ml min 1. In order to avoid contamination before use, the columns were stoppered with a TFE cap and preserved in a desiccator charged with clean activated carbon. Ultra-pure n-hexane (Wako Chem Co., Japan) was used for desorption of chlorinated organic compounds from the activated carbon. The n-hexane was also used for preparing standard solutions for measuring chlorinated organic compounds by gas chromatography.

Apparatus and methods The sampling apparatus is shown in Fig. 1. A filter containing 100 g K2 CO3 was attached to the activated carbon columns in order to prevent a decrease of the adsorption capacity of the activated carbon due to water vapor and dust. Two columns, each containing 5g of activated carbon, were connected in series. Airflow was provided by a vacuum pump connected to a glass capillary in order to keep a constant low flow-rate of ~ 3 4 1h 1t h r o u g h o u t the sampling period in spite of changes in pressure. Air sampling was conducted at four sites each in Yokohama City and Kawasaki City (Kanagawa Prefecture) every 2 weeks from June 1985 to Jul y 1986 and at seven sites in Nagoya City (Aichi Prefecture) from June 1985 to F eb r u ar y 1986. Regional characteristics near each sampling site are shown in Table 1. The pollutants adsorbed on the activated carbon were desorbed with nhexane using the apparatus shown in Fig. 2. n-Hexane was placed in a glass

123

I f

I

f f Fig. 1. Apparatus for long~term sampling. (A) K2CO3 filter; (B) activated carbon column; (C) capillary tube; (D) vacuum pump; (E) oil mist trap. syringe and passed gravimetricalIy through the activated carbon column at an up-flow of 0 . 4 m l m i n 1. T h e e f f l u e n t w a s c o l l e c t e d i n a f l a s k e x p o s e d to t h e a t m o s p h e r e b y m e a n s of a c a p i l l a r y t u b e to m i n i m i z e loss of p o l l u t a n t s . F i v e TABLE 1 Characteristics of sampling sites Site

Region

Location

Characteristics

Industrial

Daishi, Kawasaki Tajima, Kawasaki Namamugi, Yokohama Hakusui, Nagoya Chudo, Nagoya

Near Near Near Near Near

expressway expressway expressway chemical industry institute

6 7 8 9 10

Commercial

Tode, Kawasaki Noborito, Kawasaki Mamedo, Yokohama Kurokawa, Nagoya Ikeshita, Nagoya

Near Near Near Near Near

highway park station highway highway

11 12 13 14 15

Residential

Tsuda, Yokohama Tokiwadai, Yokohama Shioji, Nagoya Horagai, Nagoya Yawata, Nagoya

Near Near Near Near Near

middle school university health center water works middle school

1 2 3 4 5

124

B-~

I

C

Fig. 2. Equipment for desorption from activated carbon. (A) n-Hexane; (B) activated carbon column; (C) flask.

chlorinated organic compounds, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene were detected in the effluent using a gas chromatograph (Yanagimoto G2800EN) with an electron capture detector and a column packed with Silicone DC-550 20% on Chromosorb WAW DMCS. By comparing the amount adsorbed in the first column with that in the second, it was confirmed that the pollutants were completely recovered. The mean concentration of chlorinated organic compounds in air for the sampling period, C (ppb), was determined by the following equation from the total amounts, m (ng), in the effluent from the two columns. C

=

mRT/Mvt

where T is the mean temperature (K) over sampling period t (h), v is the mean flow-rate (1 h- 1), M is the molecular weight (g tool 1) and R is the gas constant. RESULTS AND DISCUSSION

P o l l u t i o n levels

All the data for Yokohama City and Kawasaki City from June 1985 to July 1986 are shown in Figs 3-12 for each compound. The average concentrations for five sites in the industrial region, five in the commercial region, and five in the residential region are shown in Table 2 and compared with reported global

125 0.6

Zo_

z~ Site o Site

1 2

• Site o Site

3 6

o_ ~ 0.4

._5

~ 0.2

Jun.

Aug.

Oct.

Dec.

Feb.

Apr.

Jun.

Month

Fig. 3. Change in concentration of chloroform from June 1985 to July 1986 (I). 0.6

o

Z g

0.4

~

0,2

Site

7

Site

8

u

Site

11

•

Site

12

o (9

J un.

Aug.

Oct.

Dec.

Feb.

Apr.

Jun.

Month

Fig. 4. Change in concentration of chloroform from June 1985 to July 1986 (IT). 0.6

v

o~ 0.4

Site u Site

1 2

•

3

S!te

0.2

Jun.

Aug.

Oct.

Dec.

Feb.

Apr.

Jun.

Month

Fig. 5. Change in concentration of carbon tetrachloride from June 1985 to July 1986 (I). 0.6~

~04 ~ s i

o Site z~ S i t e o Site

2

7

8 11

0.2

0

i Jun.

i

~

Aug.

i Oct.

i

L Dec.

i

i Feb.

r

i Apr.

i

i

i

Jun.

Month

Fig. 6. Change in concentration of carbon tetrachloride from June 1985 to July 1986 (II).

126 8

Site

1 2 3

~, H/~ I~/

~._o ~ aSite

~6,0

, Site

l #1/

g g2.C u 0 Jun.

Aug.

Oct.

Deci

Feb.

Apn

Jun.

Month

Fig. 7. Change in concentration of 1,1,1-triehloroethane from June 1985 to July 1986 (I). 8.0

Site ~ Site u Site o

~6.0

7

8 ~

11

~ ~.0 ~c 2.(? uo I

Jun,

I

I

I

Aug.

I

I

Oct.

I

I

Dec.

I

Feb.

I

Ill

Apr.

I

I

Jun.

Month

Fig. 8. Change in concentration of 1,1,1-trich]oroethane from June 1985 to July 1986 (II). 4.0 S ite a Site " Site

1 2 3

5o ~

"-'~3"0

/~/~

t "/

/~

~ 2.0

~ ~.¢

o u

0

I ~ Jun.

i Aug.

I I Oct.

i I Dec.

I I Feb.

I I Apr.

I I Jun,

Month

Fig. 9. Change in concentration of trich]oroethy]ene from June 1985 to July 1986 (I). 4.0

&3.o g

o Site z~ Site a Site

7 8 11

2.0

o u

1.0 O Jun.

Aug

Oct.

Dec.

Feb.

Apr.

Jun.

Month

Fig. 10. Change in concentration of trichloroethylene from June 1985 to July 1986 (II).

127 z,.O Site u Site • Site o Site

3.0

1 2 3 6

~u 2,0 2

~.0 o £J

o Jun.

Aug.

Oct,

Dec.

Feb.

Apr.

Jun.

Month

Fig. 11. Change in concentration of tetrachloroethylene from June 1985 to July 1986 (I). l,.0

~ 3.0

o

Site

?

o

Site Site

8 11

.-~ 2.0 E ~ 1.C o (.9

0 Jun.

Aug.

Oct.

Dec. Mont

Feb.

Apr.

Jun.

h

Fig. 12. Change in concentration of tetrachloroethylene from June 1985 to July 1986 (II).

pollution levels. The values obtained by subtracting the global pollution levels from the measured concentrations give the local pollution levels near the sampling sites. The concentrations of chloroform and carbon tetrachloride, which are mainly used as raw materials for industrial chemicals, were low. The concentrations of carbon tetrachloride were similar to the global pollution levels, especially in the commercial and residential regions. The concentrations of chloroform were slightly elevated at several sites near chemical plants (Site 4), an institute (Site 5), a university (Site 12), and a health center (Site 13) in which chloroform was used. The concentrations of 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene found were much higher than the global pollution levels at all sites. The discharge of these compounds from factories and facilities has a considerable influence on air pollution in urban areas. This was confirmed by the fact that the concentrations determined during the New Year period, when such discharges appeared to be light, were low at all sites.

Regional differences Since the concentrations of chloroform and carbon tetrachloride were low, regional differences in their concentrations were not evident. However, it was obvious that the concentrations of 1,1,1-trichloroethane and trichloroethylene,

128 TABLE 2

Average concentrations (ppb) of chlorinated organic compounds from 1985 to 1986 at each sampling site Site

CHCI~

eel 4

CC13CH 3

CC12CHC1

CC12CC12

1 2 3 4 5 Mean

0.11 0.10 0.1O 0.32 0.22 0.17

0.23 0.20 0.16 0.12 0.15 0.17

2.4 3.3 1.9 3.0 3.0 2.7

1.0 1.1 1.0 2.3 1.4 1.4

0.68 0.53 0.45 0.82 0.64 0.62

6 7 8 9 10

Mean

0.07 0.06 0.08 0.08 0.07 0.07

0.14 0.11 0.14 0.09 0.09 0.11

3.0 2.1 2.4 2.4 1.4 2.3

1.5 0.77 1.0 0.57 0.40 0.85

0.51 0.96 0.72 0.58 0.58 0.67

11 12 13 14 15 Mean

0.07 0.16 0.49 0.09 0.07 0.18

0.12 0.16 0.09 0.09 0.09 0.10

2.0 1.5 1.4 1.5 1.7 1.6

0.90 0.58 0.43 0.53 0.70 0.63

0.45 0.34 0.37 0.48 0.36 0.40

GlobaP

0.013

0.11

0.14

0.002

0.007

a

Kirshmer and Ballschmiter, 1983; M a k i d e et al., 1987.

which were used for washing various metal parts, were high at sites in the industrial regions. The concentrations of tetrachloroethylene, which is not only used for washing metal parts but also for washing clothing in dry cleaning establishments, were high at the sites in the industrial and commercial regions. The concentrations of chlorinated organic compounds for the different regions could be ranked as follows: industrial region > commercial region > residential region. Seasonal variations Seasonal variations in the concentrations of chloroform and carbon tetrachloride were very slight, with the concentration of carbon tetrachloride being approximately constant at many sites. The concentrations of 1,1,1-trichloroethane, trichloroethylene and tetrachloroethylene, however, tended to be low in summer and high in fall and winter. They also tended to be slightly low in spring and slightly high during the rainy season. The amounts of pollutants discharged seemed to be almost the same for all seasons. The concentrations in air varied with season, however, because of weather conditions such as wind speed, wind direction, insolation, hours of sunlight, atmospheric temperature, and precipitation. At all sampling sites, the wind speeds were low in fall, winter and the rainy

129

Site 8 vE

,2

o

o°//

r=0.74.

_s 0.8

0

o

~5

o

0 °

8

o

/°

0,4

3 0

,

I

0.2

,

0.3 Reciprocol

I

,

I

0.4 of wind

speed

0.5 ( s/m

)

Fig. 13. R e l a t i o n s h i p between c o n c e n t r a t i o n of t e t r a c h l o r o e t h y l e n e and reciprocal of wind speed at Site 8.

TABLE 3 Calculated i n t a k e (pg day 1) by m a n from air at each s a m p l i n g site Site

CHCl~

CC14

CC1 s CH 3

CC12 CHC1

CC12 CC12

2 3 4 5

4.9 4.4 4.4 14.0 9.8

13.0 12.0 9.2 6.9 8.6

120 160 95 150 150

50 54 49 113 69

42 33 28 51 40

6 7 8 9 10

3.2 2.6 3.7 3.6 3.1

8.1 6.3 8.1 5.2 5.2

150 110 120 120 70

74 38 49 28 20

32 60 45 36 36

11 12 13 14 15

3.1 7.2 22.0 4.0 3.1

6.9 9.2 5.2 5.2 5.2

100 75 70 75 85

44 29 21 26 34

28 21 23 30 22

WHO a EPA ~

60.0 3.8

6.0 8.0

37

60 54

20 16

1

aFrom guidelines for d r i n k i n g w a t e r quality (EPA, 1976; WHO, 1987).

130 season w h e n the c o n c e n t r a t i o n s were h i g h and the wind speed were high in spring and s u m m e r w h e n the c o n c e n t r a t i o n s were low. F u r t h e r m o r e , it is well k n o w n t h a t diffusion of air p o l l u t a n t s is inversely p r o p o r t i o n a l to wind speed. As an example, the r e l a t i o n s h i p between the c o n c e n t r a t i o n of t e t r a c h l o r o e t h ylene and the r e c i p r o c a l of the wind speed at Site 8 is s h o w n in Fig. 13; a c o r r e l a t i o n coefficient of 0.74 was found, w h i c h is n o t very high because it is a c o r r e l a t i o n for a v e r a g e values for ~ 2 weeks. On the o t h e r hand, there was no c o r r e l a t i o n between c o n c e n t r a t i o n and wind direction, precipitation, h o u r s of sunlight, or t e m p e r a t u r e . It was t h o u g h t t h a t p r e c i p i t a t i o n h a d less influence on the c o n c e n t r a t i o n s of c h l o r i n a t e d o r g a n i c c o m p o u n d s t h a n on o t h e r p o l l u t a n t s such as SOx and NOx, because t h e i r solubility in w a t e r is low and t h e y are volatile.

Intake by man I n t a k e by m a n of c h l o r i n a t e d o r g a n i c c o m p o u n d s from the a t m o s p h e r e at each site could be e v a l u a t e d from the a v e r a g e c o n c e n t r a t i o n s , i n h a l a t i o n volume, and t r a n s f e r r a t i o in the alveoli. The i n h a l a t i o n v o l u m e of a m a n is 12 000-15 0001 day 1 and the t r a n s f e r volume in the alveoli is ~ 8000-10 0001 day 1. The c a l c u l a t e d i n t a k e values are listed in Table 3 and are c o m p a r e d with the allowable i n t a k e values d e t e r m i n e d by W H O (1987) and E P A (1976) for d r i n k i n g water. It is clear t h a t p o l l u t a n t i n t a k e from air at m a n y sites exceeds the allowable levels. In o r d e r to eliminate air pollution c a u s e d by these c h l o r i n a t e d o r g a n i c compounds, r e g u l a t o r y s t a n d a r d s should be established and t e c h n i q u e s for p o l l u t i o n c o n t r o l developed a n d applied as soon as possible. ACKNOWLEDGMENT The s a m p l i n g s t a t i o n s and the w e a t h e r d a t a were t h o s e of the D e p a r t m e n t of P o l l u t i o n C o n t r o l of Y o k o h a m a City, K a w a s a k i City, and N a g o y a City. Special t h a n k s are due to members of these departments.

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131 Kawamoto, K. and K. Urano, 1987. A sampling method for monitoring of organic halogen compounds in air. J. Chem. Soc. Jpn, 1987: 174~1752. Kirschmer, P. and K. Ballschmiter, 1983. Baseline studies of the global pollution (VIII). The complex pattern of C1-C 4 organohalogens in continental and marine background air. Int. J. Environ. Anal. Chem., 14: 275-284. Makide, Y., A. Yokohata, Y. Kubo and T. Tominaga, 1987. Atmospheric concentrations of halocarbons in J a p a n in 1979-1986. Bull. Chem. Soc. Jpn, 60: 571-574. Ohta, T., M. Morita and I. Mizoguchi, 1976. Local distribution of chlorinated hydrocarbons in the ambient air in Tokyo. Atmos° Environ., 10:557 560. Rasmussen, R.A. and M.A. Khalil, 1982. Latitudinal distribution of trace gases in and above the boundary layer. Chemosphere, 11:227 235. Singh, H.B., L.J. Salas and R.E. Stiles, 1982. Distribution of selected gaseous organic mutagens and suspect carcinogens in ambient air. Environ. Sci. Technol., 16: 872-880. Urano, K., 1985. Usage and pollution control of chlorinated organic compounds. J p n J. Water Pollut. Res., 8: 269273. World Health Organization, 1987. WHO New Guidelines for Drinking-Water Quality. WHO, Geneva.