Measurements of hydrogen peroxide concentrations in Tokyo and ...

J. Agric. Meteorol. 68 (1): 45–53, 2012

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Measurements of hydrogen peroxide concentrations in Tokyo and Thailand Cattleya CHUTTEANG*,†, Prathomrak NA-NGERN*, Ryota MARUSHIMA*, Masatoshi AOKI*, Nongpat CHAICHANA**, and Tiwa PAKOKTOM** *Tokyo University of Agriculture and Technology, Fuchu, Tokyo, 183-8509, Japan **Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand Abstract Gas-phase hydrogen peroxide (H2O2) is very harmful to plants when combined with ozone (O3). Information on ambient H2O2 concentrations, especially for long durations, is limited not only in Thailand and South East Asia but also in Japan. The objective of the present research was to accumulate data of H2O2 concentrations over long durations in Tokyo and Thailand. Hydrogen peroxide concentrations were monitored at Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan (lat. 35.7°N long. 139.5°E), Kasetsart University, Kamphaeng Saen, Nakhon Pathom (lat. 14.0°N long. 100.0°E) and Mae-On, Chiang Mai (lat. 18.8°N long. 99.2°E), Thailand in 2009, 2010 and 2011. During the measurement period, the monthly average H2O2 concentration in Tokyo ranged from 0.0 to 2.2 ppbv, and showed lower values in May, June and November 2010 and became zero in January, February and April 2011. In Chiang Mai, the monthly average H2O2 concentration was a little higher than that of Tokyo, ranging from 1.2 to 3.1 ppbv. The monthly average H2O2 concentrations in Nakhon Pathom were three to four times higher than those of Tokyo and Chiang Mai in the same period except March and April 2011. The diurnal characteristics of H2O2 concentrations from October to December 2009 in Tokyo and Chiang Mai were similar and high around noon and low in the morning and late afternoon. Nevertheless, the pattern of diurnal characteristics in 2010 at Chiang Mai was high in the morning and gradually decreased in the afternoon and it was different from Tokyo. In the case of Nakhon Pathom, the variation was high each time. Thus, the diurnal characteristics varied from place to place and year to year. A positive correlation between atmospheric H2O2 and O3 and air temperature in Tokyo was found in the present observation. Key words: Air pollutant, Hydrogen peroxide, Ozone, RQflex 10, Volatile organic compounds.

1. Introduction Gas-phase hydrogen peroxide (H2O2) is one of the most important precursors of hydroxyl radical gases in atmospheric chemistry. H2O2 plays an important role as a radical reservoir and sink and a major oxidant of sulfur dioxide to sulfuric acid (Calvert et al., 1985). Peroxides including H2O2 always coexist with ozone (O3) in the air via the reaction of O3 with volatile organic compounds (VOCs). The H2O2 concentrations are in the level of several ppbv (Gunz and Hoffmann, Received; May 10, 2011 Accepted; October 31, 2011. †

Corresponding Author: [email protected]

1990; Takami et al., 2003; Chen et al., 2008). At present, O3 is gradually increasing in several regions around the world and large volumes of VOCs are being emitted as a by-product of industry. Therefore, the concentrations of atmospheric peroxides can be expected to increase in the future. From an agricultural perspective, peroxides are very harmful to plants, especially when combined with O3 (Chen et al., 2005, 2010). Peroxides damage macromolecules such as nucleic acids, proteins and lipids, and strongly impact plant growth by affecting source and sink strength, reducing photosynthetic capacity, inhibiting transportation and decreasing yield accumulation (Terry et al., 1995). Chen et al. (2010) demonstrated that only 2-3 ppbv peroxides combined with 50

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J. Agric. Meteorol. 68 (1), 2012 ppbv O3 can cause more severe damage to Japanese radishes than 100 ppbv O3. Moreover increases in H2O2 were reported to be associated with forest decline (Hatakeyama et al., 1993; Takami et al., 2003). Therefore, knowledge about the concentration of H2O2 in the field is very important for agriculture and terrestrial ecosystems. In recent years, short period field measurements of hydrogen peroxides (H2O2) have been carried out in several areas in the US, Europe and Japan (Watanabe et al., 1995; Jackson and Hewitt, 1996; Das and Husain, 1999; Yamada et al., 2002; Takami et al., 2003). In Japan, Watanabe et al. (1995), Yamada et al. (2002) and Takami et al. (2003) reported that the concentration of H2O2 in the daytime is usually higher than that at night and ranged from 0.1 to 4.5 ppbv. The ambient H2O2 concentration depends on several environmental factors such as air temperature, humidity, solar radiation, seasons and areas (Gunz and Hoffmann, 1990). However, information on atmospheric H2O2 concentrations, especially for long durations, is very limited not only in Thailand and South East Asia but also in Japan. Hence, the objective of the present research was to accumulate data on H2O2 concentrations for long periods in Tokyo and Thailand to understand the annual and seasonal characteristics of ambient H2O2 in Thailand and Japan.

2. Materials and Methods 2.1 Measurement sites H2O2 concentrations were measured at three sites. (Fig. 1) The first location was at Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan (lat. 35.7°N long. 139.5°E). This measurement site, the Tokyo site, was in a city located 20 km west of central Tokyo and 15 km from Tokyo Bay. The second location was at Kasetsart University Kamphaeng Saen Campus, Kamphaeng Saen, Nakhon Pathom (lat. 14.0°N long. 100.0°E). This measurement site, the Nakhon Pathom site, contained a mix of residential and crop production areas in the central part of Thailand. It was located 80 km from Bangkok and 30 km from downtown Nakhon Pathom Province, and was surrounded by the industrial areas of Ayutthaya and Saraburi, 70 and 120 km away, respectively (see Fig. 2). The pollutants emitted by these industrial areas may have affected this measurement site in the dry season from November to January due to the steady prevailing

Tokyo

Chiang Mai

Nakhon Pathom

Fig. 1. Locations of three measurement sites in Tokyo, Nakhon Pathom and Chiang Mai. northeast wind. The industrial area of Rachaburi was located about 45 km southwest from the measurement site, and the emitted pollutants may have affected the measurement site due to the steady prevailing southwest wind that blows during the Monsoon rainy season from May to October. Within the period of MarchApril, the prevailing wind direction was from the south. In this period, there was no big industrial area which would have affected the Nakhon Pathom site. The third location was in the northern part of Thailand in Mae On, Chiang Mai, Thailand (lat. 18.8°N long. 99.2°E). This site, the Chiang Mai site, was in a rural valley area and surrounded by mountains. The measurement site was located 45 km east of central Chiang Mai. 2.2 Measurement of gaseous H2O2 Gaseous H2O2 in the air was sampled for 30-60 min with a Pyrex glass mist chamber (Cofer et al., 1985) filled with about 5 ml of distilled water. The mist chamber was placed 2 m above ground. In order to prevent photolysis of peroxides during sampling, the mist chamber was shielded with aluminum foil. A Teflon filter with a pore size of 1 μm was mounted at the sample air inlet of the mist chamber to eliminate dust. Samples were collected basically four days a month and three to five times a day in the morning, afternoon and evening from 2009 to 2011. Samples were analyzed using a portable RQflex 10 reflectometer (MERCK KGaA, Darmstadt, Germany), which measures the difference in the intensity of emitted and reflected light and allows a quantitative determination

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C. Chutteang et al.：Measurements of hydrogen peroxide concentrations in Tokyo and Thailand

N

Nov-Jan

W

May-Oct

E

S Mar-Apr Prevailing wind direction

0

Saraburi

20 km

Ayutthaya

Bangkok

Ratchaburi

Fig. 2.

Nakhon Pathom site

Location of Nakhon Pathom measurement site and surrounding big cities and industrial areas. Fig. 3, which was calibrated with an HPLC system by using a standard soluble water solution basis. The H2O2 value was the mean of three analyses made using the RQflex 10. Other pollutant gases and meteorological factors at the Tokyo site were provided by a monitoring site in Fuchu, one of the sites of the Atmospheric Environmental Regional Observation System (AEROS) in Japan. The Fuchu AEROS site is located 2 km south west of the Tokyo site.

3. Results

Fig. 3. Calibration of H2O2 concentration from RQ FLEX 10 versus HPLC system (LCSS-905; JASCO). Different symbols refer to different measurement series. of the concentration of H2O2. This equipment is a reliable way to measure H2O2 concentration as shown in

3.1 Monthly H2O2 concentrations in Tokyo, Chiang Mai and Nakhon Pathom During the measurement period, the monthly average H2O2 concentration at the Tokyo site ranged from 0.0 to 2.2 ppbv, showed lower concentrations in May, June and November 2010 (0.6, 0.6, and 0.0, respectively), and became zero in January, February and April 2011. The range of minimum and maximum air temperatures in May-June 2010 were 7-28℃, -3-14℃ in November 2010-February 2011 and 8-28℃ in April

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J. Agric. Meteorol. 68 (1), 2012

Fig. 4. Monthly average H2O2 concentration in three measurement sites. The error bars show the standard deviation.

Fig. 5. Diurnal variation of H2O2 from October to December in 2009 (a) and 2010 (b). The error bars show the standard deviation. 2011. The monthly average H2O2 concentration in Chiang Mai, was from 1.2 to 3.1 ppbv, which is slightly higher than that of Tokyo. However, the levels in March and April 2011 were high. In the case of Nakhon Pathom, the monthly average H2O2 concentrations from August 2010 to February 2011 were about three to four times higher than those of Chiang Mai in the same period except in March and April 2011 (Fig. 4). The gas-phase H2O2 concentrations measured in 2009, 2010 and 2011 are summarized in Table 1. The

H2O2 concentration ranged from below the detection limit of 0.1 to 5.1 ppbv in Tokyo. Similar results were reported in urban areas in Germany and China (Gnauk et al., 1997; Hua et al., 2008). In Chiang Mai and Nakhon Pathom, the ranges of the monthly averages were from below the detection limit of 0.1 to 6.2 ppbv and 1.4 to 15 ppbv, respectively. The high levels in Nakhon Pathom were similar to levels in farmland in Claremont and Riverside, CA, USA, which showed strong diurnal variation (Kok et al., 1978). The monthly mean H2O2 concentration in Tokyo

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Table 1. Observed atmospheric H2O2 concentrations in 2009, 2010 and 2011 in Tokyo, Chiang Mai and Nakhon Pathom based on each measured data. Site Measurement Number of Min Max Mean SD periods measurements (ppbv) (ppbv) (ppbv) (ppbv) Tokyo Oct. 29-30, 2009 5 1.0 2.4 1.7 0.6 Nov. 1-4, 2009 4 0.9 1.8 1.3 0.4 AVG 2009* 9 1.5 0.5 Apr. 30-May 3, 2010 12 ＜0.1 2.4 0.6 0.8 9 ＜0.1 1.4 0.6 0.7 Jun. 5-7, 2010 14 ＜0.1 5.1 2.2 1.6 Jul. 15-20, 2010 15 0.7 2.6 1.7 0.6 Sep. 30-Oct. 4, 2010 ＜0.1 ＜0.1 Nov. 18-21, 2010 8 0.1 0.0 AVG 2010* 58 1.2 1.2 Jan. 19-22, 2011 12 ＜0.1 ＜0.1 ＜0.1 0.0 12 ＜0.1 ＜0.1 ＜0.1 0.0 Feb. 22-25, 2011 ＜0.1 ＜0.1 ＜0.1 Apr. 14-17, 2011 12 0.0 AVG 2011* 36 ＜0.1 0.0 Chiang Mar. 15-17, 2009 29 ＜0.1 5.4 2.6 1.6 16 0.2 4.0 1.4 1.0 Mai May 2-5, 2009 15 ＜0.1 4.0 1.4 1.4 Oct. 12-14, 2009 10 ＜0.1 3.6 1.3 1.4 Nov. 20-22, 2009 ＜0.1 Dec. 23-26, 2009 21 2.7 1.2 1.0 AVG 2009* 91 1.7 1.4 Jan. 23-26, 2010 8 ＜0.1 4.7 1.4 1.5 15 0.3 6.2 2.4 1.6 Jul. 8-12, 2010 25 1.0 5.7 2.9 1.2 Aug. 12-16, 2010 23 1.1 4.1 2.4 0.8 Sep. 30- Oct. 4, 2010 25 1.3 4.8 2.6 0.9 Nov. 2-6, 2010 Dec. 25-29, 2010 25 0.5 3.6 2.1 0.8 AVG 2010* 121 2.4 1.1 Jan. 25-29, 2011 25 0.6 3.5 1.6 0.7 25 1.1 4.4 3.1 0.9 Feb. 27-Mar. 3, 2011 Apr. 4-8, 2011 25 0.8 5.4 3.0 1.0 AVG 2011* 75 2.6 1.1 Nakhon Aug. 24-27, 2010 15 6.0 14.7 9.2 2.3 4 6.0 8.1 7.1 1.1 Pathom Oct. 30, 2010 16 5.8 12.1 8.5 1.7 Nov. 12-15, 2010 Dec. 18-20, 2010 12 6.1 13.3 10.2 2.3 AVG 2010* 47 9.0 2.2 Jan. 14-17, 2011 16 4.1 9.5 6.8 1.7 20 4.8 7.1 6.0 0.7 Feb. 11-14, 2011 20 1.6 3.2 2.2 0.5 Mar. 12-15, 2011 Apr. 21-24, 2011 16 1.4 3.1 2.2 0.5 AVG 2011* 72 4.3 2.3 * average of all measurement data. was high in early summer and low in winter and early spring. The monthly mean values of the H2O2 concentration in Chiang Mai were high in July to November

2010 and March to April 2011, whereas the monthly mean concentration in Nakhon Pathom was low in March and April 2011 and high in August 2010 to

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J. Agric. Meteorol. 68 (1), 2012

Fig. 6. Correlation of peroxides with NO (a), NO2 (b), NOx (c), O3 (d), SPM (e), air temperature (f), relative humidity (g), solar radiation (h) and wind speed (i) in July (△) and October (●) 2010. All plots are based on each measured data in Tokyo site and Fuchu AEROS site. January 2011. 3.2 Diurnal characteristics of H2O2 concentration in 2009 and 2010 The diurnal characteristics of H2O2 concentrations from October to December 2009 in Tokyo and Chiang Mai had similar patterns which were high around noon and low in the morning and in the evening (Fig. 5a). Nevertheless, the pattern of diurnal characteristics of Chiang Mai in 2010 was high in the morning and gradually decreased in the afternoon (Fig. 5b), and the daily pattern was different from that of Tokyo. In the case of Nakhon Pathom, the monthly variation in concentration was high. Thus, the diurnal characteristics differed from place to place and year to year. 3.3 Correlation between H2O2 and air pollutant and meteorological data Due to the limitation of air pollutants and a lack of a meteorological database at the measurement sites in Thailand, the correlations between H2O2 and air pollu-

Fig. 7. Correlation of ozone with air temperature in Tokyo in July (△) and October (●) 2010. All plots are based on each measured data. tants and meteorological data was analyzed only in Tokyo. The correlations of H2O2 with other pollutant gases and meteorological factors at the Tokyo meas-

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urement site are shown in Fig. 6. Among them, O3 and air temperature showed a positive correlation (Figs. 6d and 6f). However, the slopes of air temperature and H2O2 were different for July and October 2010. These trends were similar to the correlation between O3 and air temperature (Fig. 7). Relative humidity showed a weak negative correlation with H2O2 in July and October 2010 (Fig. 6g). As for NO, a negative correlation was observed (Fig. 6a). NO2 and NOx showed similar patterns, which were a positive correlation in July and a negative correlation in October 2010 (Figs. 6b and 6c). However, no clear correlations were found between H2O2 and SPM or Rs and wind speed (Figs. 6e, 6h and 6i).

4. Discussion 4.1 Monthly H2O2 concentrations in Tokyo, Chiang Mai and Nakhon Pathom Gnauk et al. (1997) and Hua et al. (2008) reported that atmospheric H2O2 concentrations in urban areas in Germany and China ranged from 0 to 5.3 ppbv, with mean values of 2.1 to 2.4 ppbv. These levels are similar to those of the Tokyo site (the monthly mean ranged from ＜0.1 to 2.2 ppbv). The H2O2 concentrations in Tokyo were high in July and October 2010 and autumn and lower than the detection limit of the RQflex10 from November 2010 until April 2011. The lower H2O2 may be primarily due to lower O3 concentration and the effect of low temperatures. Sakugawa et al. (2005) reported that the H2O2 concentration in a mountainous forest area, Mt. Oyama, Kanagawa, ranged from 0.8 to 4.0 ppbv. These values are similar to the concentration of the Chiang Mai measurement site, which was located in a natural area and surrounded by mixed-deciduous forest where the monthly aver-

age level ranged from 1.2 to 3.1 ppbv. Moreover Watanabe et al. (1995) demonstrated that natural olefins such as isoprene and monoterpenes are emitted from the forest into the atmosphere and produce H2O2 and organic peroxides such as methylhydroperoxide (CH3OOH, MHP) in mountainous area in Mt. Norikura, Japan. The Nakhon Pathom measurement site was located in a mix of crop production and residential areas and close to the big metropolitan city of Bangkok. The site was surrounded by industrial areas such as Ayutthaya, Saraburi and Ratchaburi (Fig. 2). Monthly average levels from August to February were three to four times higher than those of Chiang Mai. There is a possibility that the transport of air masses from heavily polluted areas affected the Nakhon Pathom site due to steady northeast and southwest prevailing winds. The monthly average level in October 2010 was slightly low because of the high amount of rainfall in this period, which can wash out hydrogen peroxides. In March and April 2011, the site showed a low H2O2 concentration. This may be attributed to the change in wind direction to the south in March and April (Fig. 2). Gunz and Hoffmann (1990) showed that the highest H2O2 concentration was found in heavily polluted areas such as Los Angeles. According to the air pollutant data of the Pollution Control Department, Ministry of Natural Resources and Environment of Thailand, the values for O3 concentration in Bangkok and Chiang Mai were similar to Tokyo and ranged from 0-125 ppbv in 2010. However, in Bangkok, the annual average level of some VOCs such as benzene was about 6.2 μg m-3, which is about 10 times higher than that of Tokyo (the annual average level in 2008 was around 0.5 μg m-3) (Table 2). The very high concentration of H2O2 in Nakhon Pathom was probably due to the high concen-

Table 2. Yearly range of O3 and annual average of volatile organic compounds (VOC) concentration in Tokyo and Thailand in 2010 provided by AEROS of Japan and Pollution Control Department, Ministry of Natural Resources and Environment of Thailand. Site O3 (ppbv) Benzene Chloroform 1, 3-Butadiene range μg m-3 μg m-3 μg m-3 average average average Tokyo 0-115 0.5* 0.0* 0-125 4.6 0.2 0.4 Chiang Mai Bangkok 0-100 6.2 0.9 0.6 *Annual average in 2008 reported by Tajima et al. (2010) in Hachioji city, Tokyo, which is located 12 km south west of Tokyo site. - 51 -

J. Agric. Meteorol. 68 (1), 2012 tration of VOCs and also to high air temperature. The Thai Meteorological Department, Ministry of Information and Communication Technology of Thailand reported that the monthly average air temperature in 2010 was higher than that of the past, especially in lowland areas. However, the monthly average air temperature was low in January and February 2011, resulting in the lower monthly H2O2 concentrations. We also found that several plants at the Nakhon Pathom measurement site had leaf injury symptoms. 4.2 Diurnal characteristics of H2O2 concentrations in 2009 and 2010 Several observations of H2O2 concentrations showed that the concentration of H2O2 at ground level was higher in the day time and lower at night due to photochemical processes (Gunz and Hoffmann, 1990). The concentration of H2O2 in our observations at Tokyo and Chiang Mai was low in the morning, gradually increased during the afternoon and became low in the evening in 2009. The diurnal patterns of H2O2 concentrations in Tokyo and Nakhon Pathom in 2010 was similar to those of 2009, and these patterns are similar to those of several H2O2 observations made by Gnauk et al. (1997) and Hua et al. (2008). Meanwhile, the Chiang Mai measurement site in 2010 showed high values in the early morning which gradually decreased through the day time. This pattern is similar to reported H2O2 observations in mountain areas, which were high at night and low in the day time, made by Watanabe et al. (1995) and Das and Husain (1999). The high concentration of H2O2 at night is possibly due to the transport of higher H2O2 air mass from the high altitude atmospheric layer where the H2O2 concentration is higher than at ground level. It is not clear why the diurnal pattern from October to December 2009 was not the same with October to December 2010 (see Fig. 5) 4.3 Correlation between H2O2 and air pollutant and meteorological data A strong positive correlation with H2O2 is observed for air temperature and ozone. There are two possible reasons for the strong correlation between H2O2 and air temperature. Firstly, photochemical reactions are accelerated by high temperatures. Secondly, high temperatures are associated with high formation of O3, which is the key component for H2O2 production (Gunz and Hoffmann, 1990). Nevertheless, the production of H2O2 depends on the total values of formation and removal processes. Similar results are re-

ported by Takami et al. (2003) and Chen et al. (2008). However, relations between H2O2 and air temperature in July and October were significantly different. A steep slope of H2O2 against air temperature was found in July when the range of air temperature was 30-38℃. On the contrary, a gentle slope was observed in October when the range of air temperature was only 1826℃. This suggests that the range of air temperature may be important for accelerating the formation and removal process of hydrogen peroxide in the atmosphere. The correlation between O3 and H2O2 seems to be the strongest among the factors we examined. Several reports have shown the same positive correlation (Jackson and Hewitt, 1996; Takami et al., 2003; Chen et al., 2008). This may be because O3 is not only a precursor to produce OH and HO2 radicals via photochemical reactions, but is also the substance which produces H2O2 by reacting with VOCs (Gunz and Hoffmann, 1990). A negative correlation is observed for nitric oxide (NO). Hydrogen peroxide is a product of hydroperoxyl (HO2) radical recombination which is produced by the reaction during photolysis of ozone and an oxidation product of hydrocarbon. Nitric oxide is one of the gases affected by this reaction. At high NO concentration, the reaction of HO2 with NO regenerates OH and reduces HO2 (Gunz and Hoffmann, 1990; Aneja and Das, 1994). Thus, the H2O2 concentration was low when NO was high.

5. Conclusion We found that the monthly average level of H2O2 in Chiang Mai ranged from 1.2 to 3.1 ppbv, which was a little higher than the range in Tokyo. However, in Nakhon Pathom, it was about three to four times higher than that of Chiang Mai and Tokyo. The diurnal characteristics in H2O2 concentration were found to be dependent on place, year and season. It appears that H2O2 concentration is directly dependent on O3; however, air temperature indirectly affects H2O2 concentration. Systematic measurement data of H2O2 would be required to determine how its concentration will increase in the future and how this will affect agricultural and natural plants.

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Acknowledgements The authors are thankful for the portion of the data


which was obtained via a collaboration of Kasetsart University and Tokyo University of Agriculture and Technology under the Education Program for FieldOriented Leaders in Environmental Sectors in Asia and Africa (FOLENS). We wish to thank Assoc. Prof. Dr. Onwona-Agyeman Siaw and Dr. Amy Lynn Burton for correcting the English in the manuscript. C. Chutteang and P. Na-gnern are grateful to the Japanese Government and FOLENS, Tokyo University of Agriculture and Technology for awarding the scholarship.

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