Monitoring Study on Acid Rain in Kanagawa Prefecture, Central Japan

研究論文 1-11

Hiromi Kobori 1,MakiKumazawa 2,Yoshiki Kai 3 and Young-Sik Ham 4

Introduction

Acid deposition has a long historical background. In the 17th century, scientists noted the ad- verseeffectsthat industry and acidic pollution had on vegetation and people. However, the term acid rain was not coined until two centuries later when British scientist Robert Angus Smith pub- lished ‘Air and Rain : The Beginning of a Chemical Climatology’ in 1872. Acid deposition is de- fined as the atmospheric acids deposited on the earth as wet deposition(snow, rain, fog, mist, etc.) and dry deposition (gas and dry particles). However, this paper deals exclusively with what is commonly called “acid rain”. Acid rain forms in the air, and is caused by burning fossil fuels to produce electricity and run automobiles. The burning of these fuels results in emissions of sulfur dioxide and nitrous oxide into the air. In the 1960s, the problems associated with acid rain be- came an international concern when fishermen noticed declines in both fish numbers and diversity in many lakes throughout North America and Europe. Indeed, acid rain has become one of the most serious worldwide environmental problems to date. The Environment Agency, Government of Japan－renamed the Ministry of the Environment, Government of Japan in 2001－has been performing surveys of acid rain since 1983. In recent years, acid rain in Japan has been observed at roughly the same levels as those in Europe and North America (Ministry of the Environment, Government of Japan, 2004). Inaddition, starting in 1984, a more detailed investigation of acid rain began in Yokohama City－located in Central Ja- pan－by the Yokohama Environmental Science Research Institute. They have been collecting and analyzing rainfall and their initial 1 mm rainfalls, which were then used for determining the differences within one-time collected rainfall. However, sampling sites for acid rain monitoring by federal and local governments are limited, and it is necessary to accumulate more data in local ar- eas in Japan. The following study monitored acid rain at two sites in Kanagawa Prefecture where acid rain previously had not been monitored. This study analyzed rainfall in 1 mm increments, in order to (1) estimate the effect of acid rain on ecosystems and (2) explain the relationship between one- time collected rainfall and the initial 1 mm rainfall.

1 Professor, Faculty of Environmental and Information Studies, Musashi Institute of Technology 2 Furezenium Kawazui, Co.Ltd. 3 Chuhoku Seiyaku, Co.Ltd. 4 Visiting researcher, Faculty of Environmental and Information Studies,Musashi Institute of Technology

97 Materials and Methods

The rainfall was collected at a residential area in Kagawa, Chigasaki City, Kanagawa Prefec- ture (E139°24′,N35°19′)inMay-December 2000 and in Eda-cho, Aoba area, Yokohama City, Kanagawa Prefecture (N35°33′,E139°33′)inJanuary-December 2002 (Figure 1). The rainfall collector (Horiba, AR-8II) was set-up using one automatic open rain sensor cap and 8 cups used for collecting the initial rainfall in 1 mm increments (Figure 2). Amounts over 8 mm of rainfall were collected by one drainage cup up to 30 mm. After collection, the rainfall pH and electrical conductivity (EC) of each cup were measured using a pH meter (Horiba, Twin pH B-212) and a EC meter (Horiba, TwinCond B-173). Statistical analyses were conducted using XLSTAT software (1995-2004 Addinsoft, XLSTAT 7.1) ; as described in the text, significant differences among the rainfall data were analyzed by Student’s t test for paired samples (α<0.01) and Pearson’s correlation coefficient test (α<0.01).

Yokohama City point Rain sensor cap

Drainage

Tokyo Bay

Chigasaki City point

10 km

FigureFigure 1. 1. The The collecting collecting pointspoints ofof rainfall rainfall in in FigureFigure 2. 2. Rainfall Rainfall collector collector KanagawaKanagawa Prefecture Prefecture

Results

Acid rain below pH 5.6 was observed in 83% of 103 rainfall samples collected in Chigasaki City (2000) and Yokohama City (2002) (Figure 3). In the detailed result of the collected rainfall sample, the volume-weighted mean pH (VWMpH) of rainfall showed an average pH of 4.7 in Chigasaki City in 2000 (range from pH 3.6 to 7.7), and VWMpH of rainfall in Yokohama City wasestimated at an average pH of 5.3 in 2002 (range from 3.9 to 7.5). Furthermore, it has been concluded that rainfall below pH 4.0 can damage certain varieties of plants (Evans et al. 1980 ; Jacobson 1980). In our study, readings at or below pH 4.0 were observed 6 times in Chigasaki City and once in Yokohama City during the study periods of 2000 and 2002. Umeda and Katou (2002) reported that the rainfall pH in Yokohama City decreased as a

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㪸㪊㪩㪉㪈 2000 2001 2002 㪇㪏㪏㪈㪐㪇㪋㪈㪎㪋㪈㪉㪊㪎㪇㪌㪅㪅㪅㪈㪈㪉㪈㪈㪈㪉㪉㪉㪉㪱㪱㪅㪅㪅㪅㪅㪅㪅㪅㪘㪛㪦㫃㪄㪄㪡㫅㫅㪪㪪㪘㪤㪡㪊㪇㪡㪡㪈㪉㪅㪅㪦㪤 Collecting date

FigureFigure 3. The3. The rainfall rainfall pH inpH Chigasaki in Chigasaki City (2000) City and(2000) Yokohama and City (2002) in Kanagawa Prefecture (Dashed line : acid rain at pH Yokohama City (2002) in Kanagawa Prefecture (The dashed 5.6 ; Solid line : acid rain at pH 4.0, crop-damageable level ; 2001 : noline: data) acid rain below pH 5.6, Solid line: crop-damageable level below pH 4, 2001: no data) result of volcanic gases emitted duing the eruption of Mt. Oyama (elevation : 813 m, location : N 34°04′43″,E139°31′46″)inMiyakejima Island, which is located 160 km south of Chigasaki City, during September 2000-August 2001. Also, particularly strong acid rain was detected in Chi- gasaki City from August to December 2000. This may bearesult of differences in the intensity of volcanic gases over time. As above-mentioned, it can be concluded that during the study periods most of the rainfall pHs were observed in the 4.0 - 5.6 range. Of particular note, acid rain below pH 5.6 was observed in 56% of 103 initial 1 mm rainfall samples in Chigasaki City (2000) and Yokohama City (2002) (Figure 4). Contrasting with the result of Umeda and Katou (1998 and 2002), our data indicated a higer level of pH (less acidic) for the initial 1 mm rainfall. Even though the reason forthis result is not clearly understood, it is in- teresting to note that initial first 1 mm rainfall pHs were significantly different from one-time collected rainfall pHs in our study (Figure 5). Umeda and Katou (1998) reported that the concentrations of each measured ion in initial first 1mmrainfall were higher compared with its one-time collected rainfall. This result may reflect that rainfall pH is dependent on the processes of proton (H+)formation and consumption of limited materials (e.g. : H2SO4,NH3,etc.) in the air. Consequently, there is a possibility that the chemical property of the initial first 1 mm rainfallmeasurements was different from their rainfall measurements. In our study, there was a significantdifference between the initial first 1 mm rainfall electrical conductivity (EC)－which estimates the amount of total dissolved salts (TDS) or the total amount of dissolved ions in the water－and the rainfall EC (Figure5).In addition, as acid rain pH decreased downward to pH 3.6 there was a corresponding increase in the acid rain EC, with a significant correlation coefficient between pH and EC in each of the initial 1 mm acid rain measurements and corresponding one-time full rainfall measurements below pH 5.6 (Figure 6).

99 㪏㪎㪍㪟㫇

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㪸㪊㪩㪉㪈 2000 2001 2002 㪇㪏㪏㪈㪐㪇㪋㪈㪋㪎㪈㪊㪉㪇㪎㪌㪅㪅㪅㪈㪈㪈㪉㪈㪉㪈㪉㪉㪉㪱㪱㪅㪅㪅㪅㪅㪅㪅㪅㪘㪛㪦㫃㪄㪄㪡㫅㫅㪪㪪㪘㪤㪡㪊㪇㪡㪡㪈㪉㪅㪅㪦㪤 Collecting date FigureFigure 4. 4. The The initial initial first first 1 1 mm mm rainfall rainfall pHs pH inin ChigasakiChigasaki CityCity (2000)(2000) and and Yokohama Yokohama City City (2002) (2002) (Dashed in lineKanagawa : acid rainPrefecture at pH 5.6 ; Solid line : acid rain at pH 4.0, crop-damageable level. 2001 : (Dashed line: acid rain below pH 5.6, Solid line: crop-damageable no data) level below pH 4, 2001: no data) ) 1

- 300 m 10 1400 m R = 0.701*** c

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µ 200 t

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r ) i 1

1000 C - f

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m l 6 a 100 c l 800 i

t a H i S f p n µ n I

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a 0 r 400 C 2 E 3456 200 Initial first 1 mm rainfall pH 0 0 150 ) R = 0.578*** 1

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Figure 5. 5. Means Means of of (1) : (1)initial Initial first 11 mmmm

C 50 E

rainfall pHs and (2) one-time colleted rainfall pHs and (2) their rainfall pHs, and l l a rainfall pHs ; (3) Initial 1 mm rainfall f 0 n

(3) initial first 1 mm rainfall ECs and (4) i a 3456

ECs and (4) one-time collected rainfall R ECs.their Verticalrainfall barsECs. indicateVertical maximumbars indicate and Rainfall pH minimummaximum valuesand minimum (n=103). Symbolvalues (n=103). of *** Figure 6. 6. Relationships Relationships between between initial initial first showsSymbol aof significant*** shows a difference significant (Student’sdifference α 11mmrainf mm rainfallall pH pH and and EC EC (n=58,(n=58, upper), up- ttestforpairedsamples,(Student's t test for paired =0samples,.001) α = andper), their and rainfall one-time pH collected and EC rainfall(n=85, 0.001) pH and EC (n=85, bottom). Symbol of bottom).*** shows Symbols significant of *** correlation show significant coef- correlationficients (Pearson’s coefficients correlation (Pearson's coeffi- correlationcient test, αcoefficient=0.001) test, α = 0.001)

100 Conclusion

This study showed acid rain in Kanagawa Prefecture was still observed with a high frequency of 83% in 103 rainfall samples in Chigasaki City (2000) and Yokohama City (2002). Also, there wasasignificant difference between the initial 1 mm rainfall pH and the one-time collected rainfall pH in Kanagawa Prefecture through the study periods of 2000 and 2002. Significantly, acid rain was more acidified with increasing acid rain EC in this study. Furthermore, the initial first 1 mm rainfall ECs were higher compared with their one-time collected rainfall ECs. This result suggests that a high concentration of dissolved ions was absorbed by the initial first 1 mm rainfall. Consequently, this study suggests that further study on effect of the frequency of rainfall on an ecosystem is required to illuminate the complex ecological effects of acid rain. Especially in unique conditions such as active volcanoes, acid rain can be further acidified within a regional wide area in Japan. Consequently, a successive monitoring study of acid rain in Japan is needed to explain acid rain and elucidate possible countermeasures.

Acknowledgments

We thank Ms. Brenda Bushell, Musashi Institute of Technology and Mr. Adam Lobel for their help during the preparation of this article.

References

Evans, L. S., C. A. Conway and Lewin (1980) Yield responses of field-grown soybeans exposed to simulated acid rain. In Proceedings of an International Conference of Ecological Impact of Acid Precipitation, Sandefjord, Norway, March 11-14, 1980, Eds. D Drablös and A Tollan, p. 162-163, Oslo-Aas, Norway : SNSF project Jacobson, J. S. (1980) The influence of rainfall composition on the yield and quality of agricul- tural crops. In Proceedings of an International Conference of Ecological Impact of Acid Pre- cipitation, Sandefjord, Norway, March 11-14, 1980, Eds. D Drablos and A Tollan, p. 41-46, Oslo-Aas, Norway : SNSF project Kanagawa Prefecture Agriculture, Forestry and Fisheries Information Center (2004) Meteorologi- cal Information Database. http : //web05.agri.pref.kanagawa.jp/kisyo/ Ministry of the Environment of Japan (2004) State of the Global Environment at a Glance : Acid Deposition. http : //www.env.go.jp/en/topic/acid/acid_situ.html Umeda, T and Y. Katou (1998) Successive progress ofpHand chemical property in rainfall in Yokohama City (Japanese title was translated into English by author). In Annual Report of Yokohama Evironmental Science Research Institute. p. 11-20, Yokohama Environmental Sci- ence Research Institute,Yokohama (in Japanese) Umeda, T and Y. Katou (2002) Acid rain by volcanic gases from Miyakejima (Part. 2). In Annual Report of Yokohama Evironmental Science Research Institute. p. 117-121, Yokohama Environ- mental Science Research Institute, Yokohama (in Japanese) Umeda, T and Y. Katou (2002) Survey of Acid Rain in Yokohama City. -Rain acidity data from January to December 2000-. In Annual Report of Yokohama Evironmental Science Research Institute. p. 139-142, Yokohama Environmental Science Research Institute, Yokohama (in Japa- nese)

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