Volume 1 No. 2, August 2011
International Journal of Science and Technology
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Diurnal and Seasonal Variations in Surface Ozone Levels at Tropical Semi- Urban site ,Nagercoil , India, and Relationships with Meteorological Conditions K.Elampari, T.Chithambarathanu Department of Physics, S.T.Hindu College, Nagercoil, India-629002
ABSTRACT Surface ozone measurements at the southernmost tropical semi-urban site Nagercoil (8o11’ N, 77o29’ E, 25m), India has been studied for the first time for the period from 2007 to 2010. A Gas Sensitive Semiconductor (GSS) sensor based ozone monitor is used for measurement. The measurement showed that the ozone concentration is a function of time and it varies from morning minimum to afternoon maximum. Temperature shows a good positive correlation whereas relative humidity shows a negative correlation with ozone. The correlation between wind speed and ozone is found to be insignificant at the measuring site. Results of this study have revealed that the annual mean of daily average surface ozone concentration varies from 18.91 ppb to 20.08 ppb. The highest average seasonal concentration was observed in summer and lowest in north east monsoon. Keywords: Surface Ozone, Air Pollution, GSS, Diurnal variations, Meteorological parameters.
I. INTRODUCTION Surface ozone (O3) or ground level ozone is the potential problem of developing countries. It plays various roles in the earth atmosphere even though its abundance is very low. Its role in the atmospheric environment through radiative and chemical processes is very significant. According to the intergovernmental Panel on Climate Change (IPCC) (2001), it is regarded as the third most powerful green house gas in the atmosphere after CO 2 and CH4 with a radiative forcing of +0.35 Wm-2. Each additional molecule of ozone produced in the atmosphere is 1200-2000 times more effective in global warming than an additional CO2 molecule [1]. It is both cytotoxic and phytotoxic in nature. Short-term exposures to ambientlevel O3 concentrations have been shown to result in a spectrum of adverse effects on the human respiratory system, including drops in lung function (i.e., measures of lung volume and expiratory flow rates), increases in lung reactivity to other irritants, and pulmonary inflammation [2]. Young children may be particularly sensitive to O3, because significant lung development continues postnatally[3]. Recent literature also shows that the estimated number of ozone related deaths during the period June–August 2000, 2002 and 2003 in Netherlands were 990, 1140 and 1400, respectively [4]. Also it is now clearly established that ozone, at the ambient concentrations can cause a range of ill effects to plants. Although plants have evolved protective mechanisms to prevent ozone damage, there is a threshold ozone concentration above which the plant’s detoxification processes can no longer cope[5]. The effects that occur include reductions in crop yield and quality, growth reductions, changes in morphology and physiology, visible injury, and early senescence [6,7,8]. Significant losses of agricultural production often occur at ozone exposures
above 40 ppb, a level already reached in many Northern hemisphere countries including India[9]. The results of the study conducted by Deb et al., (2009)[10] clearly indicate that presently the enhanced concentrations of ozone can have a potential impact on crop yield and forest over the large areas of India. Surface ozone is not emitted directly into the atmosphere. It results from photochemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight [11].Photo chemical production, Chemical destruction, Atmospheric transport, Surface dry deposition on vegetation, water and other materials and Stratospheric-Tropospheric exchanges are the five main factors which control the tropospheric ozone levels [12]. At the surface level, photochemical ozone formation depends on a number of natural and anthropogenic factors. High surface ozone concentrations are not only confined to urban environment but are also spreading to the relatively cleaner areas in remote locations [1]. The reduction of surface ozone is an important objective of air quality policy for many governments. At present, ozone is measured in very few cities in India. Significant amount of research, including monitoring and modelling of surface ozone pollution, is required to draft policies for its control
II. OBJECTIVE OF THE STUDY In this study an attempt has been made to address briefly some of the important issues, relevant to the changing climate scenario, with special emphasis on temporal (diurnal and seasonal) variations in surface ozone over a tropical semi-urban site. Study related with the inter relation of ozone and available meteorological parameters (Relative humidity, Temperature, Rainfall, and Wind speed) is also carried out and discussed. 80
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OF
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STUDY
35.00
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60.00 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Nagercoil (8o11’ N, 77o29’ E, 25m), the headquarter of Kanniyakumari district and the 12 th largest city in the state of Tamilnadu, situated close to the southern tip of peninsular India, is the study area (Figure 1).
Min.Temp Ws (km/h)
RH (%)
III. METEOROLOGY AREA
Temperature (oC), wind speed (km/h)
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It is located about 15 km from Kanniyakumari where the Bay of Bengal, Arabian Sea and Indian Ocean merge and is 6 km away from Arabian Sea. According to Assistant Director of Statistics, the climate of this region is divided into four seasons. The winter season extends from January to February followed by summer from March to May. The South West monsoon (SWM) period starts from June and ends in September, while the North East monsoon (NEM) period commences from the month of October and ends in mid-December. This region experiences a very humid and warm summer and temperature reaching up to 32oC. The approximate yearly rainfall of this district is 1188.6 mm. The weather is influenced by the Western Ghats mountain range and has a very tropical type of climate. Unlike other districts in the state of Tamil Nadu, India, Kanniyakumari district receives rainfall both during the SWM and the NEM and displays a distinct variation in the climatic conditions in itself. Figure 2 shows the average monthly variations in minimum and maximum temperature, relative humidity, wind speed, and rainfall during the observational period. The site records an average minimum temperature of 25 oC (July & December) and an average maximum of 32 oC (April). The average difference between the maximum and minimum temperature among the seasons differs only by less than 2 oC. During the measurement period the average highest relative humidity was found during July and lowest during March. Wind speed records its maximum value during August and minimum during December. It is evident from the Figure 2 the observational site is strongly influenced by the north east monsoon rainfall.
Rainfall …
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
Figure 1: Location of the observational site
300.00 250.00 200.00 150.00 100.00 50.00 0.00
Figure 2: Average monthly variations of meteorological variables.
Methods Surface ozone measurements were carried out for all the possible days in a month at local times 5:30, 08:30, 11:30,17:30, 20:30, 23:30 and 02:30 hr IST. Observations were made from March 2007 to February 2010, comprising 36 months, 12 seasons and 3 years. The instrument chosen for the study was a portable Aeroqual Series 200 monitor employing GSS sensors. This particular instrument was chosen for its simplicity and reliability in operation, ease of handling, cost and quickness in obtaining the gas concentration directly. The measurement units being either ppm or µg/m3. The ozone sensor was calibrated against a certified UV photometer. Aeroqual monitors with GSS ozone sensors were used by several authors for the measurement of the atmospheric ozone and nitrogen dioxide [13,14,15,16,17,18,19,20].
Results The measured O3 data is analyzed on the basis of diurnal, seasonal and annual variations. All hourly values were used to analyze diurnal variability and daily averaged values were used to analyze the day-to-day variability. Monthly means are calculated from the daily values, to study the seasonal cycle. The overall distribution of data 81
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So the diurnal variation represents overall budget of production and loss process. The overall mean diurnal variation for the entire study period 2007-2010 is represented in Figure 5.
Ozone (ppb)
points concerning the O3 concentration is given in Figure 3 with respect to the annual time scale.
Figure 3: Surface ozone distribution, 2007 -2010
Obviously, from the more generalized picture it is understood that the accumulation of data points are high at 10 to 15 ppb range with secondary maxima at 25 to 30 ppb.
Frequency distribution of surface ozone concentration
45-50
41-45
36-40
31-35
26-30
21-25
16-20
5-10
28 24 20 16 12 8 4 0 11-15
Frequency (%)
The frequency distribution of O3 in different concentration ranges is illustrated in Figure 4. It is clear
Surface ozone interval (ppb) Figure 4: Frequency distribution of surface ozone
From the Figure 4 that 70% of all measurements in the total data points of 3688 are in the 05- 25 ppb range, 29% of measurements are in the range 26-40 ppb and the remaining 1% measurements are above 40 ppb. The highest distribution is at 11-15 ppb (24.70%) and the lowest distribution is at 45-50 ppb (0.14%). It is also noted that 50% data are in the range 15-35 ppb.
Diurnal Variations The diurnal variation of surface ozone is helpful to understand the different processes responsible for ozone formation and destruction at this particular location. Chemical and atmospheric dynamic processes regulate the diurnal ozone concentration. A typical diurnal ozone variation coincides with the intensity of solar radiation where as the maximum ozone is shifted towards afternoon.
40.00 35.00 30.00 25.00 20.00 15.00 10.00 5.00 0.00 5:30 8:30 11:3014:3017:3020:3023:30 2:30
Time, hr (IST) Figure 5. Diurnal variation of surface ozone during the period 2007-2010
During the entire period of study the surface ozone concentration varied from the minimum of 6 ppb to a maximum of 49 ppb. The diurnal cycle of ozone was characterized by the maximum ozone concentration in the afternoon (14:30 hr) and minimum ozone concentration in the early hours of the morning (05:30 hr). A gradual decrease was observed in the evening hours (17:30 hr). After sunset, the concentration declining further and reached the lowest level between 02:30 hr and 05:30 hr. The cycles showed that the relationship between the buildup of ozone precursor gases in the morning hours and the photochemical formation of ozone around the noon time. The increase of ozone concentrations during daylight hours is attributed to the photolysis reactions of NO2 and photo oxidation of VOC’s, CO, hydrocarbons and other O3 precursors. It is also attributed to the downward transport of ozone by the vertical mixing, due to convective heating, which takes place during daytime hours [21,22]. In the evening, ozone concentration decreases steadily because the night inversion layer is formed and once it is formed, no great changes occur [22]. The low values at night were attributed to the destruction of ozone by a rapid reaction between ozone and nitric oxide (NO titration) and also there was no photolysis of O3 precursors taking place due to the absence of sunlight. The rate of increase in the morning was faster whereas the rate of decrease in the evening was quite slower. This means that, in situations with significant ozone formation, destruction of O3 is small compared to the rate of O3 production. The process of NOx titration can only remove at most one O3 per emitted NO, whereas that of ozone formation typically produces four or more O 3 per NO emitted [23]. The diurnal behaviour of surface ozone at this place could be explained on the basis of the basic atmospheric processes. The rate of photolysis of NO2 increases due to intense solar radiation produces atomic oxygen in an energetically exited state which is followed 82
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Time , hr (IST)
Winter 2009-10
NEM 2009
SWM 2009
Summer2009
NEM2008
Winter 2008-09
SWM2008
Summer2008
NEM 2007
30.00 28.00 26.00 24.00 22.00 20.00 18.00 Winter 2008-09
02:30
23:30
20:30
17:30
14:30
11:30
08:30
Summer SWM NEM Winter
SWM 2007
45.00 40.00 35.00 30.00 25.00 20.00 15.00 10.00 5.00 0.00 05:30
Ozone (ppb)
The diurnal variation of average ozone concentration which includes four different seasons for the study period 2007-2010 is shown in Figure 6.
Summer 2007
Seasonal Variations
maximum and minimum values of daily surface ozone values. The seasonal average diurnal amplitude of surface ozone for each year is given in Figure 7. From this figure it is inferred that the seasonal average of diurnal amplitude, in general lies within the range of 20.11 to 29.50 ppb. It shows that, under favorable conditions the atmosphere concerned can produce 30 ppb of ozone concentration in a day and even in unfavorable condition the atmosphere could build up a concentration of 20 ppb. A closer sinusoidal pattern of variation observed from the Figure 7 indicates the seasonal dependence of ozone concentration. Ozonce (ppb)
by a reaction to produce two OH radicals. This OH radical plays an important role in atmospheric oxidation processes of many organic compounds and there by supports the photochemical ozone production [24,25].
Seasons
Figure 6: Seasonal diurnal variation of surface ozone
High levels of average O3 concentrations were reached in summer followed by south west monsoon and winter and low values at NEM. From the Figure 6, it can be seen that in summer the highest mean ozone concentration is 38.45 ppb and the lowest is about 10.31 ppb. For the SWM the highest value is 33.44 ppb and the lowest is 8.86 ppb. The maximum and minimum mean ozone concentration in winter is 33.30 ppb and 10.55 ppb respectively. The NEM values are lower than that of winter and SWM. The diurnal pattern between different seasons shows a reasonable consistency in its behaviour. The variation in ozone concentration in different seasons may be due to the variation in NOx, CO, CH4, hydro carbon levels and changing meteorological conditions like solar radiation, temperature, cloud coverage, wind velocity , wind direction, relative humidity and rainfall. Low ozone concentrations observed in NEM was attributed to the non-availability of adequate solar radiation due to the cloudy skies that reflected back the solar radiation from reaching the surface, and also the reduction in precursor species from the atmosphere by rain which took place during this season.
Seasonal average of diurnal amplitude One more statistical tool used to reveal the actual characteristic of the location concerned is the diurnal amplitude. Diurnal amplitude is the difference between the
Figure 7: Seasonal average of diurnal amplitude
Variation of parameters
ozone
with
meteorological
Variation in surface ozone concentration depends not only on precursor emissions but also on meteorological conditions. Meteorological variables such as solar radiation, near surface wind, temperature and precipitation influence (i) ozone formation, (ii) deposition and transport process by affecting photochemical reactions and (iii) atmospheric dynamic conditions [26,27,28]. Clear skies, warm temperature, solar radiation and soft winds are believed to have a great influence on surface ozone concentration [29]. The influence of available meteorological variables on the surface ozone concentration at the observational site is discussed briefly in the following sections.
Correlation between surface ozone
temperature and
The relation between ozone concentration and temperature is shown in Figure 8. The ozone concentration is at peak when temperature is the maximum which indicates ozone concentration levels are directly related to temperature.
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Ozone
Temperature
31.00
35.00
30.00
30.00
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25.00
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0.00
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8:30
11:30 14:30 17:30 20:30 23:30 2:30
Time , hour(IST)
Figure 8: Average diurnal variations of temperature and surface ozone at Nagercoil (2007-2010)
Ambient air temperatures differ with seasons of the year and time of the day. During the study period, average maximum temperature about 32oC was observed in summer and average low temperature of about 25oC was observed in monsoon months. In all seasons, it was observed that the highest temperature was reached at 14:30 hr. Table 1 shows the correlation between average temperature (Tavg) and average ozone (Oavg) on seasonal scale.
Table 1: Correlation between Tavg and Oavg Correlation between Tavg and Oavg Season
R
P
Summer
0.64
9.1040E-15
SWM
0.49
3.1600E-11
NEM
0.66
3.5530E-15
Winter
0.69
3.1910E-11
A scatter plot in Figure 9 clearly shows the correlation between temperature and ozone in different seasons.
Temperature (o C )
Ozone concentration (ppb)
40.00
A significant correlation (r=0.66 , p < 0.000) is found during the NEM. This can be explained on the basis of decisive role of temperature on the formation of surface ozone rather than the other boundary layer processes and local emissions of precursors since the role of boundary layer processes and local emissions of precursors in deciding the ozone levels might be minimized during NEM. The temperature solely plays the catalytic role of ozone formation in this season. This is a unique observation made at the study location. It is found that the overall correlation between temperature and ozone concentration (r) is 0.59 (p < 0.000) which clearly indicates the role of photochemical reactions in the formation of ozone at the study place. Also a simple linear regression analysis on average ozone concentration and average temperature gives R2 =0.3471 with slope = 1.686. The positive slope indicates temperature played a significant role in enhancing the formation of ozone in the study area.
Correlation between wind speed and surface ozone It is known that there is a clear relationship between ambient air quality and wind speed and wind direction. These two parameters are important for the dispersion and transport of ozone and its precursors from their emission sources [29]. At the place of study, the average wind speed varied from a minimum of 3.70 km/hr to a maximum of about 14.80 km/hr during the study period. The monthly averages were in the range of 6 km/hr to 10 km/hr. July and August experienced maximum wind speed. Table 2 gives the correlation between Oavg and average wind speed (Wavg) in different seasons.
Table 2 Correlation between Wavg and Oavg Correlation between Wsavg and Oavg Season
R
P
Summer SWM NEM Winter
0.11 0.01 -0.04 -0.02
0.2448 0.9020 0.6525 0.8537
From the Table 2 and from the scatter plot in Figure 10 it is clear that at the study place wind speed played an insignificant role in reducing the concentration of ozone by dispersion or transportation. The reason for this insignificant correlation can be attributed to insufficient wind dynamics and local wind circulation patterns that could not make any alteration on the dispersion and transportation of surface ozone. Figure 9: Scatter plot between Tavg and Oavg during different seasons
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d
Figure 11: Scatter plot between Rhavg and Oavg during different seasons
The average daily ozone concentration was in slight negative correlation with the average wind speed during NEM and winter seasons and in slight positive correlation in summer and SWM season.
Correlation between relative humidity and surface ozone Table 3 shows the correlation between average relative humidity (Rhavg) and Oavg on seasonal scale.
Correlation between Ravg and Oavg Season
R
P
Summer
-0.19
0.0383
SWM
-0.41
0.0000
NEM
-0.33
0.0005
Winter
-0.12
0.3153
A scatter plot in Figure 11 clearly shows the correlation between relative humidity and ozone in different seasons. When the humidity becomes higher, the major photochemical paths for removal of ozone will be enhanced.
Ozone (ppb)
Table 3: Correlation between average Rhavg and Oavg
40.00 35.00 30.00 25.00 20.00 15.00 10.00 5.00 0.00
Ozone
RH
90.00 85.00 80.00 75.00 70.00 65.00 60.00 55.00 50.00
RH (%)
Figure 10: Scatter plot between Wsavg and Oavg during different seasons
Moreover, due to higher atmospheric instability the photochemical process was slow down and the surface ozone was depleted by deposition on water droplets in this location. Hence the ozone concentration has a strong dependence on humidity. From the Table 3, it is clear that, even though the relative humidity shows overall negative correlation with surface ozone in all the seasons, the correlation between ozone and humidity is more pronounced in monsoons than winter and summer. Also linear regression analysis gives R2= 0.1008 with slope -0.1404. Once again the –ve slope indicates that ozone concentrations decrease with increase in RH values. The diurnal behaviour of ozone with relative humidity shown in Figure 12 indicates the inverse relationship exists between ozone and RH.
Time , hrs (IST) Figure 12: Diurnal relationship between Ozone and Relative Humidity
Correlation between Rainfall and Surface Ozone Concentration of O3 is affected significantly by clouds in the sky. Any changes of meteorological 85
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conditions and rain often result in their evident changes [30]. For example, ozone levels tend to be higher under hot, sunny conditions which are favorable for photochemical ozone production. Conversely, wet, rainy weather with high relative humidity is typically associated with the low ozone levels provided by wet ozone deposition on the water droplets [31]. Figure 13 represents the influence of monthly average rainfall on ozone during the study period. From the Figure 13, it is observed that generally low ozone levels are associated with high rainfall. Figure 14 shows the scatter diagram between average rain fall and average ozone at different seasons.
Ozone (ppb)
Nov 09
Jul 090
Mar 09
Nov 08
Jul 08
Mar 08
Nov 07
26.00 24.00 22.00 20.00 18.00 16.00 14.00 12.00 10.00
Jul 07
450 400 350 300 250 200 150 100 50 0
Mar 07
Rainfall (mm)
Rainfall Ozone
Annual average concentration
of
surface
ozone
The annual average of surface ozone concentration at this site is represented by a single value, averaged over all days/months/seasons is given in Table 4.
Table 4: Annual Average of Surface ozone Year O3 (ppb Average
2007-08
2008-09
2009-10
18.91
19.13
20.08
Figure 15 shows clearly the increasing trend of surface ozone. Surface concentrations of O3 at some places have increased by a factor of 5 since the beginning of the 20th century, corresponding to an increase of 1.6% per year and even higher (2.4%) since last few decades [1]. Ozone concentrations are observed to be increasing at the rate of 1-2% in many parts of globe in northern hemisphere [32,33]. At the study place it is found that the percentage of increase during 2007-08 to 2008-09 was 1.15 and during 2008-09 to 2009-10 it was 4.73.
Ozone (ppb)
Month Figure 13: Relation between ozone and rainfall
20.50 20.00 19.50 19.00 18.50 18.00
20.08 18.91
19.13
2007-08 2008-09 2009-10 Year Figure 15: Annual average ozone concentration
IV. CONCLUSION
Figure 14: Scatter plot between average rainfall and Oavg during different seasons
Highest average rainfall and also the lowest average O3 values observed in NEM indicate a negative relation between rainfall and ozone. The overall correlation between average rainfall and average ozone is -0.21. The reason for this negative correlation is mainly attributed to two important parameters such as cloud coverage and rainfall. The thick cloud coverage prevailing in the season prevented solar radiation to reach the surface and also heavy down pour of rain washes away the precursor gases through wet deposition.
As a result of the field study conducted at Nagercoil, a tropical semi-urban site, in southernmost region of India, a data pool of surface ozone concentration was obtained with a sample size of 3688 data points. From the above analysis, the following inferences are made. -
-
-
The frequency distribution of data points accounts only to 30% for the 26-49 ppb range. This indicates the environment experiences a relatively low concentration range for the maximum period of time. The diurnal pattern of surface ozone concentration clearly indicates its dependency on the photochemical production process rather than from on-site vertical or horizontal transport. In general the surface ozone concentration is observed to the highest in summer, and lowest in north east monsoon. The winter and south west 86
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-
-
-
monsoon values lie in between these two extreme values. The seasonal variations were mostly due to the in-situ photochemistry. The analysis confirms that the ozone concentration was mostly positively correlated with air temperature and negatively with the relative air humidity. The correlation between wind speed and ozone is insignificant and the role of wind is not fully understood at this site. From this study, it is found that there is an increasing trend in ozone concentration. This increasing trend is supported by the general pattern of variation and trend observed at south Indian continent. This is an indication of the increasing concentration in ozone precursor species. Concentrated study on the surface ozone concentration at the semi-urban location, Nagercoil brings forth the first hand information on the lower atmosphere. The characteristic properties were well-understood. It illustrates the healthy atmospheric conditions. Although surface ozone concentrations are below the national standard at present, it has the potential to be a problem in the future with increased anthropogenic activities.
ACKNOWLEDGEMENT The authors wish to thank India Meteorological Department, India and Weather Services International, USA, for providing the meteorological data.
REFERENCES [1] Lal, S., Trace gases over the Indian region, Indian Journal of Radio & Space Physics, vol.36, 556-570, 2007. [2] Kinney, P.L.,Thurston, G,D., and Raizenne, M., The effects of ambient ozone on lung function in children: A reanalysis of six summer camp studies. Environmental Health Perspectives. 104 (2), 170-174, 1996 [3] Finkelstein, J,N., and Johnston, C.J, Enhanced sensitivity of the postnatal lung to environmental insults and oxidant stress. Pediatrics. 113, 10921096, 2004. [4] Pulikesi, M., Baskaralingam, P., Rayudu, VN., Elango, D., Ramamurthi , V., Sivanesan,S. ,Surface ozone measurements at urban coastal site Chennai, in India. Journal of Hazardous Materials B137, 1554–1559, 2006.
[5] Karenlampi, L., Skarby, L., Critical levels for ozone in Europe: testing and finalizing the concepts. Department of Ecology and Environmental Science, University of Kuopio, 363, 1996 [6] Fuhrer, J., and Achermann, B., Critical levels for ozone: a UN-ECE workshop report, Swiss Federal Research Station for Agricultural Chemistry and Environmental Hygiene, (FAC Report, No. 16), 1994 [7] Finnan, J.M., Jones, M.B. and Burke, J.I., A time-concentration study on the effects of ozone on spring wheat (Triticum aestivum L.) I. Effects on yield. Agriculture, Ecosystems and Environment,57: 159–167 ,1996 [8] Gimeno, B.S., Bermejo, V., Sanz, J., de la Torre, D., Gil, J.M., “Assessment of the effects of ozone exposure and plant competition on the reproductive ability of three therophytic clover species from Iberian pastures”, Atmos. Environ., 38, 2295-2303,(2004). [9] The Royal Society, Ground-level ozone in the 21th century: future trends, impacts and policy implications. The Royal Society. Science Policy. Report 15/08, London, UK, 2008. [10] Deb Roy S, Beig,G., and Ghude,S.D., Exposure-plant response of ambient ozone over the tropical Indian region , Atmos. Chem. Phys., 9, 5253–5260, doi:10.5194/acp-9-5253-2009, 2009. [11] Lin Tang Deliang Chen Per-Erik Karlsson Yongfeng Gu and Tinghai Ou, Synoptic circulation and its influence on spring and summer surface ozone concentrations in southern Sweden, Boreal Environment Research. 14, 889-902, 2009. [12] Alvim-Ferraz, M.C.M., Mesquita, M.C., Isabel Ferreira ,M., and Sousa, S.I.V, Influence of landsea breezes on nocturnal ozone maxima observed in urban sites’, Int. J. Environment and Waste Management, vol. 6, Nos. 3/4, .293–308, 2010. [13] Akram Ali, Factors affecting on response of Broad Bean and Corn to air quality and soil CO 2 flux rates in Egypt. Water Air Soil Pollut. 195, 311–323, DOI 10.1007/s11270-008-9748-2, 2008. [14] Akram Ali, Ahmed Alfarhan, Ibrahim Aldjain, Nagat Bokhari, Wafa’a Al-Taisan, Khaled,AlRasheid and Saleh Al-Quraishi , Photosynthetic responses of pea plants (Pisumsativum L. cv. 87
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Little marvel) exposed to climate change in Riyadh city, KSA, African Journal of Biotechnology Vol. 7 (15), 2630-2636, 2008. [15] Su Lee and Shih-Wei Tsai , Passive sampling of ambient ozone by solid phase microextraction with on-fiber derivatization, Analytica Chimica Acta Vol. 610, Issue 2, 149-155,2008. [16] Michael Frei, Juan Pariasca Tanaka and Matthias Wissuwa , Genotypic variation in tolerance to elevated ozone in rice:dissection of distinct genetic factors linked to tolerance mechanisms”, Journal of Experimental Botany, Vol. 59, No. 13, 3741–3752, 2008. [17] Dovilė Laurinavičienė ,Ground-level Ozone Air Pollution in Vilnius City , Environmental Research, Engineering and Management, No. 3(49), 21-28, 2009. [18] Chang-fu Wu, I-Chun Kuo, Ta-Chen Su, Ya-Ru Li, Lian-Yu Lin, Chang-Chuan Chan, and ShihChieh Hsu , Effects of Personal Exposure to Particulate Matter and Ozone on Arterial Stiffness and Heart Rate Variability in Healthy Adults, American Journal of Epidemiology, Vol. 171, No. 12, 1299-1309, 2010.
environments, Atmos. Environ, 33: 1821-1845, 1995. [24] Crutzen, P.J.,Ozone in the troposphere, in: Composition, Chemistry, and Climate of the Atmosphere. H.B. Sing (Ed.), Van Nostrand Reinhold Publ., New York, 349-393,1995. [25] Seinfeld, J.H., Pandis, S.N., Atmospheric Chemistry and Physics From Air Pollution to Climate Change (2nd edition), John Wiley &Sons, Inc. New York, 2006. [26] Lennartson, G.J., and Schwartz, M.D., A synoptic climatology of surface-level ozone in eastern Wisconsin, USA. Climate Res. 13: 207-220,1999. [27] Solberg, S., Bergstrӧm, R., Langner,J., Laurila, T. and Lindskog, A. Changes in Nordic surface ozone episodes due to European emission reductions in the 1990s., Atmos. Environ.39 :179192, 2005. [28] Andersson,C.,Langner,J., and Bergstrom,R.,Interannual variation and trends in air pollution over Europe due to climate variability during 19582001 simulated with a regional CTM coupled to the ERA40 reanalysis. Tellus 59B:77-98,2007
[19] Karim N. Jallad and Cyntia Espada-Jallad , Analysis of ambient ozone and precursor monitoring data in a densely populated residential area of Kuwait, Journal of Saudi Chemical Society , Vol. 14, Issue 4,363-372, 2010.
[29] Duenas, C., Fernandez, M.C., Caiiete, S,, Carretero, J., Liger ,E., Assessment of ozone variations and meteorological effects in an urban area in the Mediterranean Coast, Science of total Environment, 299, 97-1 13, 2002.
[20] Andrea Cattaneo , Matteo Taronna , Gaetano Garramone , Carlo Peruzzo , Christian Schlitt , Dario Consonni & Domenico M. Cavallo , Comparison between Personal and Individual Exposure to Urban Air Pollutants, Aerosol Science and Technology, 44:370–379, 2010.
[30] Jianhui Bai , Study on surface O3 chemistry and photochemistry by UV energy conservation , Atmospheric Pollution Research , 118‐127, 2010
[21] Lal, S., Naja, M., Subbaraya, B.H, Seasonal variations in surface ozone and its precursors over an urban site in India, Atmos. Environ., 34,271 3-2724, 2000. [22] Tyson, P.D., Kruger, F.J., Louw, C.W., Atmospheric pollution and its implications in the Eastern Transvaal Highveld, South African National Scientific Programmes Report no. 150, 4-40, 1998.
[31] Tarasova ,O.A., and Karpetchko , A. Y., Accounting for local meteorological effects in the ozone time-series of Lovozero (Kola Peninsula) , Atmos. Chem. Phys. Discuss., 3, 655–676, 2003. [32] Oltmans, S.J.,and Levy, H.H., Surface ozone measurements from a global network, Atmos.Environ., 28, 1994. [33] Naja, M., and Lal, S., Changes in Surface Ozone Amount and its Diurnal and Seasonal Pattern, from 1954–1955 to 1991–1993, Measured at Ahmedabad (23oN) India, Geophys. Res. Lett. 23: 81-84, 2009.
[23] Sillman, S., The relation between ozone, NOX, and hydrocarbons in urban and polluted rural
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