Measurements of nitrogen dioxide concentrations at rural sites in the United Kingdom using diffusion tubes

Nitrogen dioxide concentrations have been measured at rural sites in the United Kingdom and have revealed a marked spatial variation. The annual mean NO2 concentration varies from approximately 1 microg Nm-3 in Northern Ireland to approximately 7 microg Nm-3 in East Anglia. Though the temporal resolution of the diffusion tube method is limited by exposure periods of 2-4 weeks, it was possible to detect a marked seasonal variation in NO2 concentration at all sites, with higher values in the winter than in the summer. This is in contrast to the small seasonal variation previously observed at sites in London. Sulphur dioxide concentrations were measured daily using a bubbler method and, if expressed in terms of mass of sulphur and nitrogen, the SO2 and NO2 annual mean concentrations were similar. This is in contrast to an S/N ratio of greater than 3 in total UK emissions of SO2 and NOx. It seems likely that this difference is due to a combination of the different spatial distributions and heights of emissions of SO2 and NOx, the influence of local sources of NOx, and the smaller S/N ratio in Continental European emissions.     

Abatement of sulfur hexafluoride emissions from the semiconductor manufacturing process by atmospheric-pressure plasmas

Sulfur hexafluoride (SF6) is an important gas for plasma etching processes in the semiconductor industry. SF6 intensely absorbs infrared radiation and, consequently, aggravates global warming. This study investigates SF6 abatement by nonthermal plasma technologies under atmospheric pressure. Two kinds of nonthermal plasma processes--dielectric barrier discharge (DBD) and combined plasma catalysis (CPC)--were employed and evaluated. Experimental results indicated that as much as 91% of SF6 was removed with DBDs at 20 kV of applied voltage and 150 Hz of discharge frequency for the gas stream containing 300 ppm SF6, 12% oxygen (O2), and 40% argon (Ar), with nitrogen (N2) as the carrier gas. Four additives, including Ar, O2, ethylene (C2H4), and H2O(g), are effective in enhancing SF6 abatement in the range of conditions studied. DBD achieves a higher SF6 removal efficiency than does CPC at the same operation condition. But CPC achieves a higher electrical energy utilization compared with DBD. However, poisoning of catalysts by sulfur (S)-containing species needs further investigation. SF6 is mainly converted to SOF2, SO2F4, sulfur dioxide (SO2), oxygen difluoride (OF2), and fluoride (F2). They do not cause global warming and can be captured by either wet scrubbing or adsorption. This study indicates that DBD and CPC are feasible control technologies for reducing SF6 emissions.     

Simultaneous absorption of NO and SO2 into hexamminecobalt(II)/iodide solution

An innovative catalyst system has been developed to simultaneously remove NO and SO2 from combustion flue gas. Such catalyst system may be introduced to the scrubbing solution using ammonia solution to accomplish sequential absorption and catalytic oxidation of both NO and SO2 in the same reactor. When the catalyst system is utilized for removing NO and SO2 from the flue gas, Co(NH3)(6)2+ ions act as the catalyst and I- as the co-catalyst. Dissolved oxygen, in equilibrium with the residual oxygen in the flue gas, is the oxidant. The overall removal process is further enhanced by UV irradiation at 365 nm. More than 95% of NO is removed at a feed concentration of 250-900 ppm, and nearly 100% of SO2 is removed at a feed concentration of 800-2500 ppm. The sulfur dioxide co-existing in the flue gas is beneficial to NO absorption into hexamminecobalt(II)/iodide solution. NO and SO2 can be converted to ammonium sulfate and ammonium nitrate that can be used as fertilizer materials. The process described here demonstrates the feasibility of removing SO2 and NO simultaneously only by retrofitting the existing wet ammonia flue-gas-desulfurization (FGD) scrubbers.     

生物法同时脱硫脱硝试验研究

采用轻质陶粒生物滴滤塔处理摸拟燃煤烟气中二氧化硫和氮氧化物的试验研究，探讨生物法同时脱硫脱硝的影响因素及生物降解宏观动力学。研究结果表明，生物法能有效同时去除烟气中的二氧化硫和氮氧化物，烟气同时脱硫脱硝效率分别可达99.9%和88.9%。为获得最佳烟气同时脱硫脱硝效果，二氧化硫和氮氧化物进气负荷应分别＜140 g/（m³·h）和20 g/（m³·h），循环液pH=7～8，空床停留时间为30.28 s，喷淋密度为8.81 L/（m³·h）。     

The importance of the location of sodium chlorite application in a multipollutant flue gas cleaning system

In this study, removing sulfur dioxide (SO2), nitrogen oxides (NO(x)), and mercury (Hg) from simulated flue gas was investigated in two laboratory-sized bubbling reactors that simulated an oxidizing reactor (where the NO and Hg(0) oxidation reactions are expected to occur) and a wet limestone scrubber, respectively. A sodium chlorite solution was used as the oxidizing agent. The sodium chlorite solution was an effective additive that enhanced the NO(x), Hg, and SO2 capture from the flue gas. Furthermore, it was discovered that the location of the sodium chlorite application (before, in, or after the wet scrubber) greatly influences which pollutants are removed and the amount removed. This effect is related to the chemical conditions (pH, absence/presence of particular gases) that are present at different positions throughout the flue gas cleaning system profile. The research results indicated that there is a potential to achieve nearly zero SO2, NO(x), and Hg emissions (complete SO2, NO, and Hg removals and -90% of NO(x) absorption from initial values of 1500 ppmv of SO2, 200 ppmv of NO(x), and 206 microg/m3 of Hg(0)) from the flue gas when sodium chlorite was applied before the wet limestone scrubber. However applying the oxidizer after the wet limestone scrubber was the most effective configuration for Hg and NO(x) control for extremely low chlorite concentrations (below 0.002 M) and therefore appears to be the best configuration for Hg control or as an additional step in NO(x) recleaning (after other NO(x) control facilities). The multipollutant scrubber, into which the chlorite was injected simultaneously with the calcium carbonate slurry, appeared to be the least expensive solution (when consider only capital cost), but exhibited the lowest NO(x) absorption at -50%. The bench-scale test results presented can be used to develop performance predictions for a full- or pilot-scale multipollutant flue gas cleaning system equipped with wet flue gas desulfurization scrubber.     

A short-term diffusive sampler for nitrogen dioxide monitoring in epidemiology.

An automated timed exposure diffusive sampler (TEDS) for sampling nitrogen dioxide (NO2) was developed for use in epidemiological studies. The TEDS sequentially exposes four passive sampling devices (PSD) by microprocessor controlled valves while a pump and air flow guide prevent sampler "starvation." Two TEDS units and two portable, real-time NO2 monitors were tested for accuracy, precision, sensitivity, and linearity of response. The accuracy of the TEDS was within 10 percent of the calibrated NO2 values, and precision was within 10 percent of the means of the measured values. The TEDS sensitivity was 20 to 30 ppb-hour for NO2. Co-location of the TEDS with a chemiluminescent NOx monitor (EPA reference method) showed similar responses to ambient NO2 (R2 = 0.9991). TEDS allows better time resolution than traditional diffusive samplers (i.e., Palmes tube) while sharing their ability to sample a variety of gases.     

H2O2溶液同时脱硫脱硝实验研究

二氧化硫和氮氧化物是电厂产生的主要大气污染物，研究焦点越来越集中在在一个反应器内实现同时脱硫脱硝。实验以H2O溶液作为吸收液，在自制的鼓泡反应器内，对模拟烟气进行同时脱硫脱硝的实验研究，实验结果表明：H2O浓度、反应温度、NO浓度、SO2浓度、烟气流量对脱除率影响显著，pH、氧含量对脱硝率影响不大。在整个实验范围内脱硫效率总是保持在98．5％以上，脱硝效率最高达到67．4％。     

Effects of sulphur dioxide and nitrogen dioxide, singly and in mixture, on the macroscopic growth of three birch clones

An investigation of some aspects of the effects of low concentrations of the gases, sulphur dioxide and nitrogen dioxide, singly and in mixture, was made on the growth of three birch clones, two of Betula pendula Roth. (silver birch) and one of Betula pubescens Ehr. (downy birch). Comparative measurements of the growth form and dry mass increment were made over one year in glasshouses supplied with charcoal-filtered ambient air, and SO(2) and NO(2), singly or in mixture, at mean concentrations of 62 ppb (nl litre (-1)) of one or both gases. The main effects were found in those plants that were fumigated with SO(2) singly, and SO(2) and NO(2) together. Both treatments induced premature leaf loss and reduction in mass, especially of roots, the effects increasing over time. The heights and initial leaf areas were maintained, apparently at the expense of other parameters. NO(2), if present singly, had little or no effect, but it tended to enhance the damaging effect of SO(2) when the two were applied together. The different clones showed different degrees of response to the pollutants, but these differences became less marked during the second season of fumigation. The effects found are discussed in relation to the annual growth of trees, particularly birch.     

Economics of an integrated approach to control SO2, NOX,HCl, and particulate emissions from power plants

An integrated approach for the simultaneous reduction of major combustion-generated pollutants from power plants is presented along with a simplified economic analysis. With this technology, the synergistic effects of high-temperature sorbent/coal or sorbent/natural gas injection and high-temperature flue gas filtration are exploited. Calcium-based (or Na-based, etc.) sorbents are sprayed in the post-flame zone of a furnace, where they react with S- and Cl-containing gases to form stable salts of Ca (or Na, etc.). The partially reacted sorbent is then collected in a high-temperature ceramic filter, which is placed downstream of the sorbent injection point, where it further reacts for a prolonged period of time. With this technique, both the likelihood of contact and the length of time of contact between the solid sorbent particles and the gaseous pollutants increase, because reaction takes place both in the furnace upstream of the filter and inside the filter itself. Hence, the sorbent utilization increases significantly. Several pollutants, such as SO2, H2S, HCl, and particulate (soot, ash, and tar), may be partially removed from the effluent. The organic content of the sorbents (or blends) also pyrolyzes and reduces NOx. Unburned carbon in the ash may be completely oxidized in the filter. The filter is cleaned periodically with aerodynamic regeneration (back pulsing) without interrupting furnace operation. The effectiveness of this technique has been shown in laboratory-scale experiments using either rather costly carboxylic salts of Ca or low- to moderate-cost blends of limestone, lime, or sodium bicarbonate with coal fines. Injection occurred in the furnace at 1150 degrees C, while the filter was maintained at 600 degrees C. Results showed that 65 or 40% SO2 removal was obtained with calcium formate or a limestone/coal blend, respectively, at an entering calcium-to-sulfur molar ratio of 2. A sodium bicarbonate/coal blend resulted in 78% SO2 removal at a sodium-to-sulfur molar ratio of 2. HCl removal efficiencies have been shown to be higher than those for SO2. NOx reductions of 40% have been observed with a fuel (coal)-to-air equivalence ratio, phi, around 2. The filter has been shown to be 97-99% efficient in removing PM2.5 particulates. Calculations herein show that this integrated sorbent/filter method is cost-effective, in comparison with current technologies, on both capital cost ($/kW) and levelized cost ($/ton pollutant removed) bases, if a limestone/coal mixture is used as the sorbent for fossil fuel plants. Capital costs for the filter/sorbent combination are estimated to be in the range of $61-$105/kW for a new plant. Because current technologies are designed for removing one pollutant at a time, both their cost and space requirements are higher than those of this integrated technique. At the minimum projected removal efficiencies for HCl/SO2/NOx of about 40%, the levelized costs are projected to be $203-$261/ton of combined pollutant SO2/HCl/NOx and particulates removed from coal-fired power plants.     

The exchange of nitric oxide, nitrogen dioxide and ozone between pasture and the atmosphere

Fluxes of NO, NO2 and O3 were determined over a drained marshland pasture in south-east England by using flux-gradient techniques. Nitric oxide was found to be emitted at rates of up to 40 ng m(-2) s(-1), the rate of emission being related to the magnitude of the eddy diffusivity. Nitrogen dioxide deposited at rates of up to 90 ng m(-2) s(-1) under the control of stomatal resistance, a clear diurnal cycle being observed. Minimum canopy resistance was of the order of 80 s m(-1). Ozone deposition was also controlled by stomatal resistance, the minimum canopy resistance being around 100 s m(-1) and fluxes reaching a maximum of 220 ng m(-2) s(-1). Corrections made to NO and NO2 fluxes to compensate for chemical reactions showed flux divergences of the order of 30% for NO and NO2, but these were not statistically significantly different from the measured fluxes. The pasture was found to be a net sink for nitrogen in the form of NOx.     

Rural concentrations of nitrogen dioxide pollution throughout Wales

Monitoring of nitrogen dioxide was carried out at over 50 rural sites in Wales throughout 1986. All sites were chosen so as to be remote from any local sources of NO(2) and the values obtained were deemed to be minimum values for the different regions. Measurements were made using a diffusion tube technique which aimed to give mean concentrations of NO(2) for 2-week exposure periods. The results obtained have been used to generate pollution maps to show mean monthly levels of NO(2) for rural environments throughout Wales. It is apparent that levels of NO(2) are generally higher during the winter months. In addition, annual mean concentrations of the pollutant are greatest in the north-eastern and south-eastern parts of Wales with the lowest levels being found along the western coast. The work marks the completion of the first national survey of nitrogen dioxide pollution in Wales. The data are discussed in terms of the potential threat rural concentrations of NO(2) pose to crops and natural vegetation.     

Measurements of nitrogen dioxide and sulphur dioxide concentrations in urban and rural areas of Poland using a passive sampling method

Measurements of 1-month concentrations of NO(2) and SO(2) were carried out in the period from May 1993 to April 1994 in 147 points in 30 major cities of Poland and in 31 points in rural areas. The measurement points were divided into five classes representing: centres of cities, residential areas, industrial areas, traffic locations and rural areas. Passive samplers were prepared in one laboratory, mailed to local laboratories for sampling and then returned for analysis. The same samplers were used for collecting both NO(2) and SO(2). Analyses for NO(2) absorbed as nitrite were made spectrophotometrically after reaction with Saltzman reagent. Sulphur dioxide was determined as sulphate with ion chromatography. The consistency of data allowed comparison of levels of air pollution in different cities and the production of maps of spatial distribution of NO(2) and SO(2) in rural areas of Poland.     

Effects of sulfur dioxide and nitric oxide on mercury oxidation and reduction under homogeneous conditions

This paper is particularly related to elemental mercury (Hg0) oxidation and divalent mercury (Hg2+) reduction under simulated flue gas conditions in the presence of nitric oxide (NO) and sulfur dioxide (SO2). As a powerful oxidant and chlorinating reagent, Cl2 has the potential for Hg oxidation. However, the detailed mechanism for the interactions, especially among chlorine (Cl)-containing species, SO2, NO, as well as H2O, remains ambiguous. Research described in this paper therefore focused on the impacts of SO2 and NO on Hg0 oxidation and Hg2+ reduction with the intent of unraveling unrecognized interactions among Cl species, SO2, and NO most importantly in the presence of H2O. The experimental results demonstrated that SO2 and NO had pronounced inhibitory effects on Hg0 oxidation at high temperatures when H2O was also present in the gas blend. Such a demonstration was further confirmed by the reduction of Hg2+ back into its elemental form. Data revealed that SO2 and NO were capable of promoting homogeneous reduction of Hg2+ to Hg0 with H2O being present. However, the above inhibition or promotion disappeared under homogeneous conditions when H2O was removed from the gas blend.     

Sulfur dioxide and nitrogen oxides emissions from U.S. pulp and paper mills, 1980-2005

Comprehensive surveys conducted at 5-yr intervals were used to estimate sulfur dioxide (SO,) and nitrogen oxides (NO.) emissions from U.S. pulp and paper mills for 1980, 1985, 1990, 1995, 2000, and 2005. Over the 25-yr period, paper production increased by 50%, whereas total SO, emissions declined by 60% to 340,000 short tons (t) and total NO, emissions decreased approximately 15% to 230,000 t. The downward emission trends resulted from a combination of factors, including reductions in oil and coal use, steadily declining fuel sulfur content, lower pulp and paper production in recent years, increased use of flue gas desulfurization systems on boilers, growing use of combustion modifications and add-on control systems to reduce boiler and gas turbine NO, emissions, and improvements in kraft recovery furnace operations.     

Effects of nitrogen dioxide on leaf chlorophyll and nitrogen content of soybean

One-month-old soybean (Glycine max [L.] Merrill), cultivar 'Williams', plants were exposed to nitrogen dioxide (0.1, 0.2, 0.3 and 0.5 ppm) and carbon filtered air (control), 7 h per day, for 5 days, under a controlled environment. Leaf chlorophyll content (Ch a, Ch b, and total Ch content) and foliar nitrogen content (%N) were determined before and after the exposure. The influence of NO(2) treatments up to 0.3 ppm on leaf chlorophyll content was negligible although a stimulatory effect was evident in Ch a and total Ch content with 0.2 ppm NO(2). Marked decline in Ch content was observed with 0.5 ppm treatment; the reductions in Ch a and total Ch were 45% and 47%, respectively. Foliar-N contents of plants treated with 0.2 and 0.3 ppm NO(2) were higher than the control; plants exposed to 0.5 ppm NO(2) showed a 41% reduction in foliar-N compared to pre-exposure values.     

Nitrogen oxides from waste incineration: control by selective non-catalytic reduction

An experimental study of the selective non-catalytic reduction (SNCR) process was carried out to determine the efficiency of NOx removal and NH3 mass balance, the NOx reducing reagent used. Experimental tests were conducted on a full-scale SNCR system installed in a hospital waste incineration plant. Anhydrous NH3 was injected at the boiler entrance for NOx removal. Ammonia was analyzed after each flue-gas treatment unit in order to establish its mass balance and NH3 slip in the stack gas was monitored as well. The effective fraction of NH3 for the thermal NOx reduction was calculated from measured values of injected and residual NH3. Results show that a NOx reduction efficiency in the range of 46.7-76.7% is possible at a NH3/NO molar ratio of 0.9-1.5. The fraction of NH3 used in NOx removal was found to decrease with rising NH3/NO molar ratio. The NH3 slip in the stack gas was very low, below permitted limits, even at the higher NH3 dosages used. No direct correlation was found between the NH3/NO molar ratio and the NH3 slip in the stack gas since the major part of the residual NH3 was converted into ammonium salts in the dry scrubbing reactor and subsequently collected in the fabric filter. Moreover, another fraction of NH3 was dissolved in the scrubbing liquor.     

Effects of nitrogen dioxide on biochemical and physiological characteristics of soybean

One month old soybean (Glycine max (L.) Merrill) cv. 'Williams' plants were exposed to nitrogen dioxide (NO2 at 0.1, 0.2, 0.3, and 0.5 microl liter(-1) and carbon filtered air (control), 7 h per day for five days, under controlled environment. Data were collected on net photosynthetic rate (PN), stomatal resistance (SR), and dark respiration rate (DR), immediately following the fifth day of exposure and 24 h after termination of exposure. Chlorophyll a (Ch a), chlorophyll b (Ch b), total chlorophyll (tot Ch) and foliar nitrogen (N) were measured before and after exposures. Growth characteristics--relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), and root shoot ratio (RSR) -- were computed for treated plants using standard growth equations. Increases of 18% and 23% in PN were observed immediately following exposure to 0.2 microl liter(-1) NO2 and after 24 h recovery period, respectively. With 0.5 microl liter(-1) NO2 treatment, reductions in PN of 23% and 50% were observed, immediately after exposure and following 24 h recovery, respectively. DR rates with 0.2 l liter(-1) treatment were higher than the control. Chlorophyll a and tot Ch showed significant reduction with 0.5 microl liter(-1) NO2 treatment. The percent reduction in Ch a and tot Ch with 0.5 microl liter(-1) NO2 were 45% and 47%, respectively. Increases in foliar nitrogen content after 0.2 and 0.3 microl liter(-1) NO2 treatments were 46% and 69%, respectively. Nitrogen dioxide at 0.5 microl liter(-1) reduced RGR and NAR by 47% and 51%, respectively. Leaf area ratio was 42% higher in 0.5 microl liter(-)1 NO2 treated plants, compared with the control; this increase was insufficient to compensate for the decrease in NAR resulting in a net decline in RGR. Nitrogen dioxide up to 0.2 microl liter(-1) increased PN and foliar-N content of soybean. With 0.5 microl liter(-1) NO2, significant decreases were observed in PN, leaf chlorophyll, foliar-N, NAR and RGR. Nitrogen dioxide up to 0.2 microl liter(-)1 has a favorable influence on overall growth characteristics of soybean; however, inhibitory effects were seen with NO2 treatment at 0.5 microl liter(-1).     

Simultaneous removal of NO and SO2 by high-temperature fluidized zero-valent iron processes

A new approach to simultaneously remove nitrogen monoxide (NO) and sulfur dioxide (SO2) by zero valent iron (ZVI) was investigated. Three different parameters, temperature, flux, and ZVI dosage, were tested in fluidized ZVI column studies containing 500 ppmv of NO and SO2, respectively. Under the ZVI dosage of 0.5 g at flux of 0.6 L/cm2 x min for temperature 573 K, there is neither NO nor SO2 reduction. For 623 K and 673 K, complete removal for NO and > 90% removal for SO2 were achieved. For temperatures of 723 K and 773 K, 100% removal was achieved for both NO and SO2. The amounts of NO or SO2 reduction (as milligrams of NO or SO2 per gram ZVI) increased as temperature increased, and linearities were observed with both correlation coefficients > 0.97. Compared with NO, SO2 had earlier breakthrough because of a slower diffusion rate and less reactivity but higher mass reduction because of a higher molecular weight for SO2 (64 g/mol for SO2 and 30 g/mol for NO). At same temperature, both NO and SO2 reductions (as milligrams of NO or SO2 per gram of ZVI) were constant regardless of either flux or ZVI dosage variation, but breakthrough time was affected by both flux and ZVI dosage. A parameter weight of ZVI/flux (W/F) was developed to represent these two parameters at the same time to assess the breakthrough time of NO and SO2. Higher breakthrough time was achieved for higher W/F value. Moreover, interestingly, longer breakthrough time and more NO and SO2 mass reduction were achieved for combined NO and SO2 than individual NO or SO2 treated by ZVI, and both oxidation and reduction reactions occurred instead of a reduction reaction only. Chemical reactions among ZVI/NO, ZVI/ SO2, and ZVI/NO/SO2 were also proposed and verified by X-ray diffraction analyses.     

Differential assimilation of nitrogen dioxide by 70 taxa of roadside trees at an urban pollution level

In order to screen for the best species for mitigating nitrogen dioxide (NO2) by plants at urban levels, we investigated assimilation of nitrogen dioxide by 70 taxa of woody plants that are mostly utilized as roadside trees. They were fumigated with 15N-labeled NO2 at 0.1 microl l(-1) for 8h, and the amount of reduced nitrogen derived from NO2 (in mg Ng(-1) dry weight) in the leaves (designated NO2 assimilation capability hereafter) were determined. Data were analyzed in the comparison with the previously reported ones obtained at 4 microl l(-1) NO2. Among the 70 taxa, the value of NO2 assimilation capability differed by a factor of 122 between the highest (Prunus yedoensis; 0.061) and the lowest (Cryptomeria japonica; 0.0005). Based on the analysis of NO2 assimilation capability values at 0.1 and 4 micro l(-1) NO2, the 70 taxa of woody plants appeared to be classified into four types; those of high NO2 assimilation and high NO2 resistance, those of high NO2 assimilation but low NO2 resistance, those of low NO2 assimilation and low NO2 resistance, and those of low NO2 assimilation but high NO2 resistance. The first, second, third and fourth types include 13, 11, 35 and 11 taxa, respectively. The broad-leaf deciduous trees may have advantages of high biomass and fast growth as compared with woody plants of other habits. Thus, four broad-leaf deciduous species, Robinia pseudo-acacia, Sophora japonica, Populus nigra and Prunus lannesiana, were concluded here to be the best phytoremediators for the urban air.     

Atmospheric conversion of sulfur dioxide to particulate sulfate and nitrogen dioxide to particulate nitrate and gaseous nitric acid in an urban area

Sulfur dioxide, nitrogen dioxide, particulate sulfate and nitrate, gaseous nitric acid, ozone and meteorological parameters (temperature and relative humidity) were measured during the winter season (1999-2000) and summer season (2000) in an urban area (Dokki, Giza, Egypt). The average particulate nitrate concentrations were 6.20 and 9.80 microg m(-3), while the average gaseous nitric acid concentrations were 1.14 and 6.70 microg m(-3) in the winter and summer seasons, respectively. The average sulfate concentrations were 15.32 microg m(-3) during the winter and 25.10 microg m(-3) during the summer season. The highest average concentration ratio of gaseous nitric acid to total nitrate was found during the summer season. Particulate sulfate and nitrate and gaseous nitric acid concentrations were relatively higher in the daytime than those in the nighttime. Sulfur conversion ratio (Fs) and nitrogen conversion ratio (Fn) defined in the text were calculated from the field measurement data. Sulfur conversion ratio (Fs) and nitrogen conversion ratio (Fn) in the summer were about 2.22 and 2.97 times higher than those in the winter season, respectively. Moreover, sulfur conversion ratio (Fs) and nitrogen conversion ratio (Fn) were higher in the daytime than those in the nighttime during the both seasons. The sulfur conversion ratio (Fs) increases with increasing ozone concentration and relative humidity. This indicates that the droplet phase reactions and gas phase reactions are important for the oxidation of SO2 to sulfate. Moreover, the nitrogen conversion ratio (Fn) increases with increasing ozone concentration, and the gas phase reactions are important and predominant for the oxidation of NO2 to nitrate.