characteristics of ionic components in precipitation in kitakyushu city, japan

Journal of Atmospheric Chem&try 17: 325-337, 1993. 325 © 1993 Kluwer Academic Publishers. Printed in the Netherlands.

Characteristics of Ionic Components in Precipitation in Kitakyushu City, Japan

Y A S U H I R O Y A M A T O , T A K A S H t Y A M A D A , and K O Z O K I D O Kitakyushu Municipal Institute of Environmental Health Sciences, Shinike 1-2-1, Tobata-ku, Kitakyushu 804, Japan

(Received: 30 June 1992; in final form: 20 May 1993)

Abstract. Precipitation samples were collected by" filtrating bulk sampler in Kitakyushu City, Japan, from January 1988 to December 1990. Volume weighted annual mean of pH was 4.93, but the pH distribution indicated that most probable value lay in the range pH 6.0-6.4. Volume weighted annual mean concentrations of maior ionic components were as follows; SO4>: 84.2, NO3: 28.t, CF: 86.3, NH~: 45.5, Ca2+: 63.3, Mg2+: 27.0, K+: 3.4, Na+: 69.0 ~ eq 1-1. The highest concentrations of these ionic components were observed in winter and the lowest occurred in the rainy season. The ratio of ex- SO42-/NO3 exhibited the lowest ratio in summer, and the highest ratio in winter. Good correlations were obtained between CI- and Na +, ex-SO~ + and ex-Ca 2+ NO~ and ex-Ca 2+, and NH~- and ex-SO]-, respectively. However, no correlation between C1- and Na + with Ca 2+ was observed. The relationship of H + with (ex-SO4 > + NO3) - (ex-Ca 2+ + NH +) indicated positive correlation.

Key words. Acid precipitation, pH, SO4 >, NO~, Ca 2+, NH~, Japan.

1. Introduction

Acidification of precipitation has damaged not only ecosystems in lakes and forests but also man-made constructions (Cheng et al., 1987; National Acid Precipitation Assessment Program, 1987), and the scale of this phenomenon is apparent across the globe. It has become an especially serious problem in Europe and North America. In Japan, the pH of bulk deposition samples decreased during the 1960s (Nishi, 1971). Since 1973, data on precipitation chemistry have been collected by many researchers (Tamaki et al., 1979; Sekiguchi et al., 1983; Dokiya et al., 1987; Fujita and Kawaratani, 1988). They indicate acidification of precipitation on forests in various areas of Japan. Also, the infuence of acid precipitation on forests is gradually being pointed out (Sekiguchi et aI., 1986; Takahashi et al., 1991). In a smvey of precipitation chemistry during the rainy season ~Iorisaki et al., 1990), it was found that the concentrations of ionic components such as NO3, SO4 >, NH 4 mad Ca > were higher in Kitakyushu than at the other sites of Kuyshu district. However, little detailed information on the concentrations of ionic components in precipitation has been obtained.

In this paper, characteristics of major ionic components in precipitation of Kita- kyushu City collected with a filtrating bulk sampler during the period January 1988 to December 1990 are reported.

326 YASUHIRO YAMATO, TAKASHI YAMADA, AND KOZO KIDO

China 40 ° N

Japan Sea

Tokyo<

East

Kitaky

I u/)Cllina Sea Pacific Ocean . _ _ _ _ _ _ _ _ _ _ ~ _ _ O~ ---------- ~-~-30 ° N

120 ° E d

130 °

200km

140 ° E

Fig. 1. Location of Kitakyushu City.

2. Methods

Figure 1 shows the location of Kitakyushu City. The city has a population of approximately 1 030 000 and has an industrial area which consists of heavy and chemical industry. However, concentration of SO 2 in the area is among the lowest registered by National Air Surveillance Network stations, and that of NO and NOz are moderate (Japan Environment Agency, 1990).

The sampling site was located on the rooftop of a building in an urban area. The samples were collected with a filtrating bulk sampler with a piece of membrane filter (pore size: 0.45 gin) attached between a funnel and a storage bottle. This sampler filter keeps out non-soluble substances and prevents the vaporization of the sample in the bottle. The samples were collected weekly and stored in a refrig- erator before the chemical analysis.

Concentrations of major ionic components such as C1-, NO3, SO ]-, Na +, NH4, K +, Mg 2+ and Ca 2+ and pH of precipitation samples were measured. The compo-

IONIC COMPONENTS IN PRECIPITATION 327

nents were analyzed using ion chromatography, and measurements of pH were made with pH electrodes. Concentration of H ÷ was calculated from pH value.

3. Results and Discussion

3.1. Mean Ionic Composition

The annual mean chemical composition of precipitation is shown in Figure 2. The equivalent concentrations of anions and cations decreased in order of C1- > SO4 2- > NO~, and Na + > Ca 2+ > NH] > Mg 2+ > H + > K +, respectively. It was thought that most of Na + and C1- originated in seasalt since the distance from the sampling site to seashore is approximately 1.5 kin. Also, the concentration of ex-C1- was only 6.0 bt eq 1-1. From the above result, it was concluded that, in Kitakyushu, the major anions responsible for acidification of precipitation were SOl- and NO~, and the neutralizing agents were mainly Ca 2+ and NH~. Also, as shown in Figure 2, nearly all SOl- and NO~ was neutralized by Ca 2+ and NH~. The sum of cation was slight- ly higher than the sum of anion. This tendency was consistently observed, as shown in Figure 3. In this study, only three components were investigated for anions. Therefore, this effect may be due to components such as organic acids and HCO~ which were not investigated here.

3.2. pH

Figure 4 shows the pH distribution of 127 weekly samples during the period from January 1988 to December 1990. The frequency at the rank of pH 6.0-6.4 was the highest, and indicated 28.3%. In addition, although the volume weighted annual mean value of pH was 4.93, about 75% of the samples showed pH 5.0 or above. High pH values were encountered when the precipitation amount was small. It is known that much C a 2+ is contained in initial precipitation and small precipitation events, and this component decreased in the succeeding precipitation (Matsumoto

K*

NH4 * Ca z * Na ÷

50 I00 35O 2OO

Concentration (~ eq 1 -~)

Fig. 2. Mean ionic composition of the precipitation in Kitakyushu.

f 250


7

o - i1} E

o e ~

e -

M

6

5

4

3

2

1

L.,"" 0 - " t

0 1

[]

e

I I I

2 3 4 5

5- Cation (meq 1-1) Fig. 3. Relationship between cation and anion,

and Itano, 1985). Perhaps, the component is acting as a neutralizing agent. There- fore, the pH values of a small amount of precipitation may be increased.

Frequency distribution of pH of each season is shown in Figure 5. In spring (March-May), frequency at the rank of pH 5.0-5.4 was the highest. However, the other seasons indicated the highest frequency at the rank of pH 6.0-6.4. In fall (September-November), relatively high frequency was also observed at the rank of pH 4.5-4.9. Moreover, more than 10% of samples in the spring and fall were shown at the rank of pH 4.0-4.4. These results indicate that the pH of rain water decreases in these seasons in Kitakyushu.


30

to

r~

00 ~q

20

70

0

m

4 . 0 4 . 5 5 - 0 5 . 5 6 . 0 6 . 5

n=127

7 . 0

pH

Fig. 4. Frequency histograms of pH of precipitation.

3.3. Seasonal Variation

Monthly variation in volume weighted mean values of pH and concentrations of ionic components are summarized in Table I, and monthly variation of equivalent ratios of various ionic components are shown in Table II. Excess (ex-) SO42- and ex- Ca 2+ were calculated using Na + as seasalt index.

The concentration of C1- decreased in summer, and increased in the cold season. That of Na + also exhibited similar seasonal variation. The ratios of C1-/ Na + varied from 1.08 to 1.40 with a mean of 1.24. The ratios were similar to that of seawater (Figure 6). Therefore, it was reasoned that the origin of most of the C1- and Na + was seasalt.

The highest concentration of ex-SO]- was observed in winter mad the lowest occurred in rainy seasons, such as June and September. The ratio of ex-SO42-/SO] -


(a)

40

30

2O

10 ̧

0 4~0 4.5 5.0

' ' Spring n=34

5 . 5 6 . 0 6 . 5 7 . 0

pH

4 0

3 0

E

20

10

Summer n=30

(b) o

I t

4.0 4.5 5.0 5,5 6.0 6.5 7.0

pK

g

D

t.I

(c)

40

30

Autumn n=30

- - - - - - I I I I

20 V'----- I t

I

0 4,0 4.5 5.0 5.5 6 . 0 6.5 7 . 0

40

3O

g

u 2o

14

10

(d) o ' 4 . 0 4.5 5.0 5_5 6.0

Winter n=33

i 6.5 7,0

pH pll

Fig . 5. pH d i s t r i b u t i o n .

decreased to 0.80 in the winter and increased to 0.96 in summer. Though ions of seasalt origin such as C1- and Na + drastically increased in comparison with other ions in winter monsoon season, the variation was small. NO3 also showed similar monthly variation, but the variation was small in comparison with SO~-.

Seasonal variations in SO]-/NO3 ratio in precipitation have been shown in Europe and North America (Galloway and Likens, 1981; Laurila, 1990). The ratio was highest in smnmer, and the lowest in winter. This might have been caused by a reduction in H2SO4 formation during the winter, because the conversion of SO 2 to H2SO4 in the atmosphere is affected by the concentration of oxidants, especially HzO2 (Calvert et al., 1985), which indicates low concentrations in winter in con-

Tab

le I

, M

onth

ly v

aria

tion

of

prec

ipit

atio

n ch

emis

try

and

prec

ipit

atio

n am

ount

Z

('3

O

0

Mon

th

pH

SO

l-

ex-S

O~-

N

O~

C

1-

NH

+

Ca

> ex

-Ca

2+

Mg

2+

(~ e

q/L

)

K +

N

a +

pA

~

(ram

)

Janu

ary

4.86

10

0.6

88.9

25

.2

126.

6 65

.5

53.4

49

.1

37.1

3.

0 97

.7

55,2

F

ebru

ary

4.94

12

4.7

111.

8 33

.2

135.

3 76

.0

85.6

81

.0

35.4

3.

9 10

7,0

79,4

M

arch

5.

34

116.

8 10

4.0

35,5

12

1.7

58.3

92

.5

87.9

38

,9

3.5

106.

0 69

.3

Apr

il

4.56

95

.3

87.6

34

.6

81.8

46

.3

78,8

76

.0

23.2

3.

2 63

.8

85.3

M

ay

4.53

83

.8

80.2

28

,5

37.2

33

.9

56.3

55

,0

15.0

3.

1 30

.3

119.

1 Ju

ne

5.19

43

.8

42.1

1 17

.7

17.6

26

.3

35.5

34

.8

10.2

1.

5 14

.2

267.

5 Ju

ly

5.24

75

.8

71,4

30

,4

39.9

63

.9

61.8

60

.2

18,8

4.

2 36

.9

72.4

A

ugus

t 5.

33

102.

3 95

.3

53.4

65

.3

54.4

10

6.7

104.

2 26

.7

4.1

57.9

53

.6

Sep

tem

ber

4.95

51

.8

48.3

19

.4

41.3

28

.1

41.6

40

,3

15.7

1.

9 29

.5

211.

3 O

ctob

er

4.91

92

.6

82.4

30

.2

107.

9 37

.3

68.0

64

.3

37.1

4.

4 84

,4

73.5

N

ovem

ber

5.57

14

5.8

116.

1 43

,4

301.

4 74

.1

111,

8 10

1.0

72.8

8.

7 24

7.1

52.9

D

ecem

ber

6.10

30

5.2

244.

5 59

.3

645,

8 16

0.4

184.

7 16

2.7

159.

3 16

.9

504,

4 33

.8

Mea

n 4.

93

84.2

76

.0

28.1

86

.3

45.5

63

.3

60.3

27

.0

3.4

69,0

97

.8

5

" PA

: Pre

cipi

tati

on A

mou

nt.

332 YASUHIRO YAMATO, TAKASHI YAM~ADA, AND KOZO KIDO

Table II. Monthly variation of equivalent ratios of various ion components

Month ex-SO4Z-/SO4 z- ex-SO4>/NO~ ex-Ca>/Ca 2+ NH~/ex-Ca 2+

January 0.88 3.52 0.92 1.33 February 0.90 3.36 0.95 0.94 March 0.89 2.93 0.95 0.66 April 0.92 2.54 0.96 0.61 May 0.96 2.81 0.98 0.62 June 0.96 2.38 0.98 0.76 July 0.94 2.35 0.97 1.06 August 0,93 1.78 0.98 0.52 September 0.93 2.49 0.97 0.70 October 0.89 2.73 0.95 0.58 November 0,80 2.68 0.90 0.73 December 0,80 4.12 0,88 0.99

trast to summer (Sakugawa et al., 1990). Conversely, the ratio in Kitakyushu was lowest in summer, and highest in winter. Similar results have been obtained at sites facing the Japan Sea coast (Mori et al., 1991). The disparity perhaps indicates that most of the ex-SO 2- was transferred from other regions by the strong northwest winds.

The concentration of Ca 2+ also showed monthly variation similar to that of SO4 >. Moreover, the concentration of ex-Ca 2+ also increased in spring. This increase may indicate the influence of bai, a mist appearing in early spring caused by fine particles of sand from China (Mukai et al., 1989). The ratio of ex-Ca2+/Ca 2+ also reveals a seasonal variation similar to ex-SO2-/SO 2-. Variation in the ratio was small, and ranged from 0.98 to 0.88. Among the sites in Kyushu area, it is known that the concentration of ex-Ca 2+ in precipitation is the highest at Kitakyushu (Morisaki et al., 1990). And, it is believed that the major sources of ex-Ca 2+ are factories because deposition of ex-Ca > is highest in industrial areas (Yamato et al., 1991). Thus, the ratio is little affected by the increase in the concentration of the seasalt Ca 2+ during the winter monsoon season.

In Kitakyushu, concentration of NH] was also the highest among the sites in western Japan compred with data on precipitation chemistry at other Japanese cities (Tamaki et al., 1991). The monthly variation was approximately similar to that of ex-Ca 2+, but the concentration of NH~ contrasted to ex-Ca 2+ and varied across a wide range. Also, NH~ drastically increased in December. Therefore, the ratio of NH~/ex-Ca 2+ varied from 0.52 to 1.33 with a mean of 0.89. The ratio increased in winter and July. Al~'icker and Mahar (1984) showed that the ratio increases for large precipitation volumes. However, this tendency was not con- firmed in this study. This ratio increase may require a high concentration of Ca 2+ in the atmosphere.


4.5

!

¢)

V

I

4.0

3.5

,.3.0

2.5

2.0

1.5

1.0

0.5

0 w

0 0.5

I I

%

%,

IN

I I I l I

l.O 1.5 2.0 2.5 3.0 3,5

Na + (meq I - I )

Fig. 6. Relationship between Na + and C1-.

3.4. Correlation between Ionic Components

Correlation coefficients calculated from the concentration of each component in precipitation produce strong correlations between all components except H +. In this study, coefficients were therefore calculated on the basis of the deposition of each ionic component. The result is shown in Table III.

The greatest correlation coefficient (r-- 0.99) was shown between C1- and Na +

taa

Tab

le m

. M

atri

x o

f co

rrel

atio

n c

oeff

icie

nts

amo

ng

ion

co

mp

on

ents

in p

reci

pit

atio

n

H +

S

O~

- N

O~

C

1-

NH

~

Ca

z+

Mg

2+

K +

N

a +

ex

-SO

42-

ex-C

a z+

H +

SO

2-

0.5

4

- N

O~

0.

65

0.76

-

el-

-0

.38

0.

29

-0.2

8

- N

H~

0.

27

0.82

0.

68

0.1

6

Ca

>

0.53

0

.89

0

.93

0

,04

M

g 2+

-0

.24

0

.54

0

.02

0

.93

K

+

0.08

0.

69

0.33

0

.69

N

a +

-0

.42

0.

26

-0,3

1

0.9

9

ex-S

O42

- 0.

65

0.98

0.

86

0.0

8

ex-C

a 2.

0.5

7

0.87

0

.96

-0

.06

0,7

7

0.3

9

0.3

2

- 0.

53

0.5

3

0.8

3

0.13

0.

01

0,9

2

0.8

2

0,9

2

0.3

5

0.7

5

0.99

0

.23

0.68

0

.56

0.

05

- 0

.46

-0

.09

0.

91

> N

©

©

IONIC C O M P O N E N T S IN PRECIPITATION 3 3 5

which are the major constituents of seasalt. Also, correlation between these components and Mg 2+ was great (r > 0.91). However, no correlation between C1- and Na + with Ca 2+ was established (r = 0.04 and 0.01, respectively). This indicates that most Ca 2+ is of non seasalt origin. In addition, a relationship between NO 3 and ionic components of seasalt origin was not found. Close relationships between ex- SO~- and NO~ with ex-Ca 2+ were found (r = 0.91 and 0.96, respectively). Also, the relationship between NH] and ex-SO 2- (r = 0.96) was closer than with NO? (r = 0.68). This suggests the presence of NaC1, Ca(NO3)2, CaSO4, ('NH4)2SO 4 and NH4NO 3 in the atmosphere. Likewise, H + correlated with ex-SO42- (r-- 0.65) and NO~ (r = 0.65). However, we postulate that most of ex-SO42- and NO? was neutralized by ex-Ca 2+ and NH~ because the deposition of H + was small compared with sum of ex-SO42- and NO~. Therefore, the relationship of H + with (ex-SO]- + N O ~ ) - (ex-Ca2+ + NH~) was also investigated (Figure 7). The relationship indicated a positive correlation. The correlation coefficient (r = 0.69) was greater than

5

4-

Z + +

I X

I.....I

I

-.I- I

I

L-.I

4

3

2

1

0

- 1

- 2

- 3

- 4

- 5

h IN II

II

I

I ................. I ........................... I 1 t 1

0 l 2 3 4 5 8

1

7 8

H + (meq m-Z)

Fig. 7. Relationship between H + and (ex-SO4 2- + NO3) - (ex-Ca 2+ + NH~).


that with ex-SO4 2- or NO~. From the above results, it is clear that pH of precipitation in Kitakyushu is mainly affected by ex-SO 2+, NO~, ex-Ca 2+, and NH~.

4. Conclusion

The investigation of precipitation chemistry in Kitakyushu City led to following conclusions.

(1) Volume weighted annual mean vlaue of p H was 4.93. But, the pH distribution indicated the highest probability in the range of 6.0-6.4. In spring (March- May), the values peaked in the range of 5.0-5.4. However, in the other seasons the values peaked in the range of 6.0-6.4.

(2) The highest concentrations of main ionic components were observed in winter and the lowest occurred in rainy season. The ratio of ex-SO2-/NO3 was lowest in summer, mad highest in winter.

(3) The greatest correlation coefficient (r = 0.99) was shown between Ct- and Na + which are the major constituents of seasalt. Strong relationships between ex- SO~- and NO~ with ex-Ca 2+ were found (r = 0.91 and 0.96, respectively). How- ever, no correlation between C1- and Na + with Ca 2+ were observed (r = 0.04 and 0.01, respectively). Also, the relationship between NH~ and ex-SO24 - (r = 0.96) was closer than with NO~ ( r - -0 .68) . The relationship between H + and (ex-SO42- + NO~) - (ex-Ca 2+ + NH~) indicated a positive correlation.

References

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Calvert, J. G., Lazrus, A., Kok, G. L., Heikes, B. G., Walega, J. G., Lind, J., and Cantrell, C. A., 1985, Chemical mechanisms of acid generation in the troposphere, Nature 317, 27-35.

Cheng, R. J., Hwu, J. R., Kim, J. T., and Leu, S.-M., 1987, Deterioration of marble structures. The role of acid rain, Analyt. Chem. 59, 104A-106A.

Dokiya, Y., Aoyama, M., Katsuragi, Y., Yoshimura, E., and Toda, S., 1987, Deposition of chemical components in Japn, in R. W. Johnson, G. E. Gordon, W. Calkins, and A. Z. Elzerman (eds.), The Chemistry of Acid Rain (ACS Symposium Series 349), pp. 258-272.

Fujita, S. and Kawaratani, R. K., 1988, Wet deposition of sulfate in the inland sea region of Japan, J. Atmos. Chem. 7, 59-72.

Galloway, J. N. and Likens, G. E., t981, Acid precipitation: The importance of nitric acid, Atmos. Environ. 15, 1081-1085.

Japan Environment Agency, 1990, Annual Report of the National Air Surveillance Network, Japan Em~ironment Agency, Tokyo, Japan.

Laurila, T., 1990, Wet depositions of major inorganic ions in Finland based on daily bulk deposition samples, I~ter Air Soil Pollut. 52, 295-324.

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Mori, A., Ohara, M., Wakamatsu, S., Murano, K., Taguchi, IC, Sekiguchi, K., Tamaki, M., Kato, H., Kitamura, M., Okita, %, Yamanaka, Y., and Hara, H., 1991, Studies on equivalent ratio of nitrate to sulofate in acid precipitation, Nippon Kagaku Kaishi 1991, 920-929.

Morisaki, S., Utsunomiya, A., Takayanagi, M., Mori, A., Imamura, O., Kawaida, T., Horal, S., Kinjyou, Y., Yarnato, Y., and Nakakuma, M., 1990, Field study of acid precipitation in the Kyushu and Okinawa district, Zenkoku Kougaiken Kaishi 15, 136-143.


Mukai, H., Ambe, Y., Muku, T., Takeshita, K., Fukuma, T., Takahashi, J., and Mizota, S., 1989, Long- term monitoring of the composition of airborne particulate matter in Dogo of the Oki Islands, Kokuritsu Kougai Kenkyusho Hokoku, No. 123, 7-42.

National Acid Precipitation Assessment Program, 1987, Interim assessment, The cause and effects of acidic deposition. IV Effect of acidic deposition.

Nishi, T., 1971, Ame mizu no pH kara mita taiki osen, Taiki Osen News No. 64, 4-5. Sakugawa, H., Kaplan, L R., Tsai, W., and Cohen, Y., 1990, Atmospheric hydrogen peroxide, Environ,

Sci. Technol. 24, 1452-1462. Sekiguchi, K., Kano, K., and U iiie, A., 1983, Acid rain (pH 2.86) in Maebashi, Taiki Osen Gakkaishi

18, 1-7. Sekiguchi, K., Hara, Y., and Ujiie, A., 1986, Dieback of Cryptomeria Japonica and distribution of acid

deposition and oxidant in Kanto district of Japan, Environ. Technol. Lett. 7, 263-268. Takahashi, K., Nashimoto, M., and Ueda, H,, 1991, Relationships among oxidant index, precipitation

and decline of Japanese cedar (Cryptmeria japonica D. Don) trees in the Kansai-Setouchi District, Kankyo Kagaku Kaishi 4, 51-57.

Tamaki, M., Hiraki, T., and Watanabe, H., 1979, Determination of major components in rain water by interval sampling method, Hyougu ken kougai kenkyusho kenkyu Hokoku 11, 1-11.

Tamaki, M., Katou, T., Sekiguchi, K., Kitamura, M., Taguclfi, K., Oohara, M., Moil, A., Wakamatsu, S, Mnrano, K., Okita, T., Yamanaka, Y., and Hara, H., 1991, Acid Precipitation Chemistry over Japan, Nippon Kagaku Kaishi 1991, 667-674.

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characteristics of ionic components in precipitation in kitakyushu city, japan

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