Maximum Incremental Reactivity Research Articles

Exhaust emissions of volatile organic compounds of powered two-wheelers: Effect of cold start and vehicle speed. Contribution to greenhouse effect and tropospheric ozone formation

Powered two-wheeler (PTW) vehicles complying with recent European type approval standards (stages Euro 2 and Euro 3) were tested on chassis dynamometer in order to measure exhaust emissions of about 25 volatile organic compounds (VOCs) in the range C1–C7, including carcinogenic compounds as benzene and 1,3-butadiene. The fleet consists of a moped (engine capacity≤50cm3) and three fuel injection motorcycles of different engine capacities (150, 300 and 400cm3). Different driving conditions were tested (US FPT cycle, constant speed). Due to the poor control of the combustion and catalyst efficiency, moped is the highest pollutant emitter. In fact, fuel injection strategy and three way catalyst with lambda sensor are able to reduce VOC motorcycles' emission of about one order of magnitude with respect to moped. Cold start effect, that is crucial for the assessment of actual emission of PTWs in urban areas, was significant: 30–51% of extra emission for methane. In the investigated speed range, moped showed a significant maximum of VOC emission factor at minimum speed (10km/h) and a slightly decreasing trend from 20 to 60km/h; motorcycles showed on the average a less significant peak at 10km/h, a minimum at 30–40km/h and then an increasing trend with a maximum emission factor at 90km/h. Carcinogenic VOCs show the same pattern of total VOCs. Ozone Formation Potential (OFP) was estimated by using Maximum Incremental Reactivity scale. The greatest contribution to tropospheric ozone formation comes from alkenes group which account for 50–80% to the total OFP. VOC contribution effect on greenhouse effect is negligible with respect to CO2 emitted.

The use of biodiesel blends on a non-road generator and its impacts on ozone formation potentials based on carbonyl emissions

In this study, emissions of carbonyl compounds from the use B50 and B100 were measured with a non-road diesel generator. A total of 25 carbonyl compounds were identified in the exhaust, including 10 with laboratory-synthesized standards. Formaldehyde, acetaldehyde, and acrolein were found as the most abundant carbonyl compounds emitted for both diesel and biodiesel. The sulphur content of diesel fuels and the source of biodiesel fuels were not found to have a significant impact on the emission of carbonyl compounds. The overall maximum incremental reactivity (MIR) was the highest at 0 kW and slightly increased from 25 to 75 kW. The MIR of B100 was the highest, followed by diesel and B50, which is consistent with the emission rates of total carbonyl compounds. This suggests that the use of biodiesel blends may be more beneficial to the environment than using pure biodiesel.

Volatile organic compounds in an urban environment: a comparison among Belgium, Vietnam and Ethiopia

The effects of urban and indoor air pollution on human health are a major environmental concern for all, but not much has been researched in the developing world. Specifically, quantitative data on the occurrence of volatile organic compounds (VOCs) – main contributors to air pollution – in Asia and Africa are scarce compared to the availability of data in the developed world. This paper presents one of the first studies focusing on the analysis and occurrence of VOCs in Vietnam and Ethiopia, which constitutes part of the novelty of this work. A spectrum of 34 VOCs was measured at eight different urban sites in Ghent (Belgium), Hanoi (Vietnam), Jimma and Addis Ababa (Ethiopia) during three sampling campaigns from September 2008 to September 2010. Sampling was done in an active way by means of sorbent tubes filled with Tenax TA. The analysis was done by TD-GC-MS using internal standard calibration. Data were interpreted and compared in terms of (i) individual, subgroup and total VOCs concentration (TVOCs), (ii) indoor-to-outdoor (I/O) concentration ratios, (iii) source identification by diagnostic ratio and/or correlation coefficients, and (iv) ozone formation potential (OFP) at outdoor sites based on up-to-date maximum incremental reactivity (MIR). I/O concentration ratios varied between 0.2 and 30, with big differences noticed with respect to the type of VOC(s) considered and the type of outdoor sampling location. The highest TVOC concentrations were measured in street samples with maximum values of 54 µg/m3 in Ghent, 507 µg/m3 in Hanoi and 318 µg/m3 in Addis Ababa illustrating the large difference in ambient air quality levels. This is also reflected in the arithmetic mean OFP values (µg/m3) of 82, 1308 and 596 in Ghent, Hanoi and Addis Ababa, respectively. Results of this study could be helpful to support formulation of national policy with regard to ambient air quality.

Volatile Organic Compounds in Roadside Environment of Hong Kong

Vehicular exhaust emissions are one of major sources of anthropogenic volatile organic compounds (VOCs) in urban areas of Pearl River Delta Region (PRDR). Six types of vehicle emission (VE)-dominated samples were collected at representative locations in Hong Kong in the winter of 2003. A total of 111 VOC species were quantified in the samples collected. n-Butane (31%) was the most abundant species in liquefied petroleum gas (LPG)-fueled VE-dominated samples, followed by propane (26%) and i-butane (25%). Toluene was the most abundant species in gasoline-fueled VE-dominated samples (16%), comprising about half of the quantified aromatic content. While ethene and ethyne have the greatest abundance in all diesel-fueled VE-dominated VOCs profiles (except at Tuen Mun Bus Depot). VOCs were also quantified at three roadside locations in Hong Kong. And ethene was the most abundant VOCs at roadside locations which accounted for 9.5 to 29% of the total quantified VOCs, except at Hong Kong Polytechnic University roadside monitoring station (PUX). Moreover, several VOCs were clearly in abundances in the roadside samples, namely toluene, ethyne, propane, ibutane, n-butane and i-pentane. Generally, strong and fair correlations were determined from the marker species of fuel vapor (i.e., LPG, gasoline, and diesel), which show significant fuel evaporation from vehicles in roadside environment of Hong Kong. Maximum incremental reactivity (MIR) was also calculated to evaluate the contributions of individual VOCs to ozone (O3) formation potential. The largest contributors to O3 production at Mong Kok roadside station (MKX) and Lok Ma Chau roadside station (LMX) were toluene (17 and 15% of the measured VOC reactivity, respectively), ethene (14 and 17% of the measured VOC reactivity, respectively), and propene (7 and 8% of the measured VOC reactivity, respectively), indicating the important roles of alkenes and aromatics in the ambient O3 formation.

Volatile Organic Compounds and Nonspecific Conjunctivitis: A Population-Based Study

Volatile Organic Compounds (VOCs) are present in both indoor and outdoor environments, and have the potential to adversely impact the health of all age groups of people that are exposed to them. This study examines and assesses the short-term effects of VOCs on nonspecific conjunctivitis. Data were collected from outpatient visits for nonspecific conjunctivitis in air-quality monitoring areas. Air quality data were collected from the Taiwan Environmental Protection Administration’s air quality monitoring stations. To find the immediate and lag effects of VOCs, an area-specific, casecrossover analysis was performed and a meta-analysis with random effects was used to combine the area-specific results. The results show that toluene, m,p-xylene, o-xylene, propylene, and benzene had higher maximum incremental reactivity (MIR) values and concentrations in air than any of the other studied VOCs. These 5 VOCs also had the strongest shortterm effects on outpatient visits for nonspecific conjunctivitis. The effect was strongest for toluene, and there was a 1.3% increase [95% confidence interval (CI), 0.4–2.2] for an interquartile range rise in concentration. The results showed no evident lag effects. This study, which combined and integrated VOC and ophthalmologic data to investigate associations between outpatient visits for nonspecific conjunctivitis and VOC levels, found that there was a correlation between these visits and the short-term effects of VOCs, suggesting possible causes for nonspecific conjunctivitis.

Identification and Apportionment of Sources of Ozone‐forming Potential for Proper Reduction Strategies

AbstractIn this study, results of source identification and apportionment for ambient volatile organic compounds (VOCs) from a previous work were used to estimate ozone‐forming potentials (OFPs) of effective sources for developing proper strategies for reduction of tropospheric ozone pollution. The source identification and apportionment of ambient VOC pollution within Yildiz Technical University's Davutpasa Campus (Istanbul, Turkey) was done by positive matrix factorization (PMF). The results suggested five effective source groups with the emissions related with paint use and solvent use having the highest contributions (36.8 and 28.2%). The results from PMF were used along with maximum incremental reactivities to estimate potentials of individual sources for ozone formation. It was found that biogenic emissions (3.78) and traffic related emissions (gasoline and diesel vehicle exhaust) (3.83 and 3.15, respectively) have the highest potential for ozone formation in terms of grams O3/g VOC emitted. The results were used to suggest proper source‐based reduction strategies for OFP.

Economic and health benefits of the co-reduction of air pollutants and greenhouse gases

This study examines the monetary value of social costs—private costs and negative externalities—that could be avoided by energy conservation actions. A novel Air Resource Co-Benefits (ARCoB) model has been developed in this study to assess the comprehensive social benefits of greenhouse gas GHG mitigation policy. The rollback model is used to estimate changes in air pollutant concentrations attributed to the emission reductions. Change in ozone concentration is converted from non-methane hydrocarbons based on the maximum ozone increment reactivity. In addition to saved medical expenditure, years of potential life lost (YPLL) is estimated based on the exposure-response coefficients for mortality and is calculated with abridged life table. Two cases of energy efficiency improvement in different scales are analyzed to estimate the annual co-benefits of abatements of air pollutants and greenhouse gas in 2009: 1) the energy intensity reduction in the industrial sector and 2) energy saving at Taipei Taiwan City Hall. Results indicate the saved energy cost accounted for 66 % and 70 % in the first and second case, respectively, and was a major part of the total benefit from energy conservation. The saved air pollution fee was 7.8–8.5 times lower than the averted health cost of medical expenditure, which was US$10.34 million in the first case, in which there were also averted YPLL of 3,478 person-years or averted deaths of 311 persons per year.

Ozone formation potentials of organic compounds from different emission sources in the South Coast Air Basin of California

Different organic compounds exhibit different propensities for ozone formation. Two approaches were used to study the ozone formation potentials or source reactivities of different anthropogenic organic compounds emission categories in California's South Coast Air Basin (SoCAB). The first approach was based on the combination of total organic gases (TOG) emission speciation profiles and the maximum incremental reactivity (MIR) scale of organic species. The second approach quantified ozone impacts from different emission sources by performing 3-dimensional air quality model sensitivity analysis involving increased TOG emissions from particular sources. The source reactivities derived from these two approaches agree reasonably well for 58 anthropogenic organic compounds emission categories in the SoCAB. Both approaches identify TOG emissions from mobile sources as having the highest reactivity. Source reactivities from both approaches were also combined with TOG emissions from each source category to produce a 2005 reactivity-based anthropogenic TOG emission inventory for the SoCAB. The top five reactivity-based anthropogenic TOG emission sources in the SoCAB during 2005 were: light-duty passenger cars, off-road equipment, consumer products, light-duty trucks category 2 (i.e., 3751–5750 lb), and recreational boats. This is in contrast to the mass-based TOG emission inventory, which indicates that livestock waste and composting emission categories were two of the five largest mass-based anthropogenic TOG emission sources. The reactivity-based TOG emission inventory is an important addition to the mass-based TOG emission inventory because it represents the ozone formation potentials from emission sources and can be used to assist in determining targeted sources for developing organic compounds reduction policies.

비메탄계 휘발성유기화합물에 의한 간접 온실효과의 산출

Indirect <TEX>$CO_2$</TEX> effect due to non-methane volatile organic compound (NMVOC) emissions from solvent and product use and fugitive NMVOC emissions from fuels in the Republic of Korea and 13 Annex I countries under United Nations Framework on Climate Change were estimated and the proportions of them to total greenhouse gas (GHG) emissions ranged from 0.092% to 0.45% in 2006. Indirect greenhouse effect (<TEX>$CO_2$</TEX>, <TEX>$CH_4$</TEX>, and <TEX>$O_3$</TEX>) were estimated at 13 photochemical assessment monitoring sites in the Republic of Korea using concentrations of 8 NMVOCs of which indirect global warming potential (GWP) were available. The contribution of toluene to mixing ratio was highest at 11 sites and however, the contribution of toluene to indirect greenhouse effect was highest at nine sites. In contrast to toluene, the contributions of ethane, butane, and ethylene were enhanced. The indirect greenhouse effects of ethane and propane, of which ozone formation potentials are the lowest and the third lowest respectively among targeted 10 NMVOCs, ranked first and fourth highest respectively. Acetaldehyde has relatively higher maximum incremental reactivity and is classified as probable human carcinogen however, its indirect GWP ranked second lowest.

Non-methane Hydrocarbons and Their Ozone Formation Potentials in Foshan, China

Concentrations of non-methane hydrocarbons (NMHCs) were measured to investigate their temporal variations and major sources, and to explore the ozone formation potentials (OFP) of each NMHCs for the first time in December 2008 in Foshan. Ethane, propane, n-butane, i-pentane, 2,3-dimethylbutane, ethene, propene, ethyne, benzene and toluene were the 10 most abundant hydrocarbons, accounting for 82% of the concentration of total NMHCs. Concentrations of these hydrocarbons as well as their fractional contributions to the total NMHCs were higher in the morning and evening than in the afternoon, consistent with the variations in vehicle volumes during these periods. This suggests that the vehicular emission was likely the major source of NMHCs at this site. The mean B/T ratio (0.45 ± 0.24) further supported vehicular emission as the main source of the ambient NMHCs except for aromatic hydrocarbons. These aromatic hydrocarbons were mainly from solvent evaporation, as indicated by the diurnal variations in the ratios of toluene and m/p-xylene to benzene. The results from factor analysis also showed that combustion process and solvent usage were the major sources of NMHCs. On average, total Prop-Equiv and OFP were 153.0 ppbc and 863.4 μg/m 3 , respectively. Based on MIR (maximum incremental reactivity) scale, the leading contributors to OFP in decreasing concentrations were ethene, toluene, propene, i-pentane, m/p-xylene, 1-butene, ethylbenzene, o-xylene, 2,3-dimethylbutane and trans-2-butene, which in total explained 77% of the total OFP. Ranking by Prop-Equiv, the top 10 species were propene, toluene, ethene, 1-butene, i-pentane, m/pxylene, isoprene, 2,3-dimethylbutane, trans-2-butene and ethylbenzene, accounting for 66% of the total Prop-Equiv. Thus, alkenes played the most important role in O3 formation, followed by aromatics and alkanes during the study periods in Foshan.

Prediction of Maximum Incremental Reactivities of Octane and Cetane Improvers.

Prediction of Maximum Incremental Reactivities of Octane and Cetane Improvers.

Carbonyls speciation in a typical European automotive diesel engine using bioethanol/butanol–diesel blends

Carbonyl compounds have been lately measured among researches in diesel exhaust emissions, due to its high atmospheric reactivity. This reactivity is quantified by the Maximum Incremental Reactivity, MIR. However, if comparing different fuels or engine conditions, weighing the emissions generated with their respective MIR is necessary. This weighed parameter is the specific reactivity, SR. The sampling procedure varies from author to author, since it is not normalized. In this paper, exhaust samples were pumped directly through the 2,4-dinitrophenylhydrazine cartridges, without any air dilution ratio. A diesel engine Nissan Euro 5 M1D-Bk, equipped with intercooler, diesel oxidation catalyst and diesel particle filter was used. Four operating modes were chosen from the New European Driving Cycle, two from the urban subcycle and two from the extra-urban one. Samples were collected at three different points along the exhaust pipe, to study the effect of two post-treatment systems. A pure diesel fuel, as reference, and two blends, one with a 10% v/v of bioethanol and another with a 16% v/v of butanol, were used during experiments. For the analysis, a High Performance Liquid Chromatograph, with a C-18 column and ultraviolet–visible detector, was used. Results showed that the emissions of the blends tested were higher than the diesel ones. Besides, in all fuels, urban mode (U10) was the mode with highest emissions. The reduction of emissions due to the post-treatment systems was detected in all fuels too.

Effects of low pressure exhaust gas recirculation on regulated and unregulated gaseous emissions during NEDC in a light-duty diesel engine

Regulated and unregulated gaseous emissions with high pressure and low pressure EGR (exhaust gas recirculation) system were tested in a 4-cylinder, light-duty diesel EURO IV engine typically used in European vehicles. Four different engine calibrations with the low pressure EGR system were studied. Regulated emissions of NO X , CO, HC and CO 2 were measured for each configuration. Unburned Hydrocarbon Speciation, HCHO (formaldehyde), HCOOH (formic acid) and N 2O (nitrous oxide) were also measured in order to determine the MIR (maximum incremental reactivity) of the gaseous emissions. Pollutants were measured without the DOC (diesel oxidation catalyst) to gather data about raw emissions. When the low pressure EGR system was used, decreases in NO X , N 2O and fuel consumption were observed and significant increases HC, CO and unregulated emissions; this is the result of a lower intake manifold temperature, which provides a higher gas density which modifies the combustion process. The potential of tropospheric ozone production was higher in all cases when the low pressure EGR was used.

Characterizations of volatile organic compounds during high ozone episodes in Beijing, China

Air samples were collected in Beijing from June through August 2008, and concentrations of volatile organic compounds (VOCs) in those samples are here discussed. This sampling was performed to increase understanding of the distributions of their compositions, illustrate the overall characteristics of different classes of VOCs, assess the ages of air masses, and apportion sources of VOCs using principal compound analysis/absolute principal component scores (PCA/APCS). During the sampling periods, the relative abundance of the four classes of VOCs as determined by the concentration-based method was different from that determined by the reactivity approach. Alkanes were found to be most abundant (44.3-50.1%) by the concentration-based method, but aromatic compounds were most abundant (38.2-44.5%) by the reactivity approach. Aromatics and alkenes contributed most (73-84%) to the ozone formation potential. Toluene was the most abundant compound (11.8-12.7%) during every sampling period. When the maximum incremental reactivity approach was used, propene, toluene, m,p-xylene, 1-butene, and 1,2,4-trimethylbenzene were the five most abundant compounds during two sampling periods. X/B, T/B, and E/B ratios in this study were lower than those found in other cities, possibly due to the aging of the air mass at this site. Four components were extracted from application of PCA to the data. It was found that the contribution of vehicle exhaust to total VOCs accounted for 53% of VOCs, while emissions due to the solvent use contributed 33% of the total VOCs. Industrial sources contributed 3% and biogenic sources contributed 11%. The results showed that vehicle exhausts (i.e., unburned vehicle emissions+ vehicle internal engine combustion) were dominant in VOC emissions during the experimental period. The solvent use made the second most significant contribution to ambient VOCs.

Concentration characteristics of VOCs and acids/bases in the gas phase and water-soluble ions in the particle phase at an electrical industry park during construction and mass production

The electronics industry is a major business in the Central Taiwan Science Park (CTSP). Particulate samples and 11 water-soluble ionic species in the particulate phase were measured by ionic chromatography (IC). Additionally, acid and base gases were sampled by denuder absorption and analyzed by IC. Volatile organic compounds (VOCs) were collected in stainless-steel canisters four times daily and analyzed via gas chromatography/mass spectrometry. Ozone formation potential (OFP) was measured using maximum increment reactivity. In addition, airborne pollutants during (1) construction and (2) mass production were measured. Particulate matter concentration did not increase significantly near the optoelectronic plant during construction, but it was higher than during mass production. SO2, HNO2 and NH3 were the dominant gases in the denuder absorption system. Nitrate, sulfate, and ammonium ions predominated both in PM2.5 and PM10−2.5; but calcium ion concentration was significantly higher in PM10−2.5 samples during construction. Toluene, propane, isopentane, and n-butane may have come from vehicle exhaust. Construction equipment emitted high concentrations of ethylbenzene, m-xylene, p-xylene, o-xylene, 1,2,4-trimethylbenzene, and toluene. During mass production, methyl ethyl ketone), acetone and ethyl acetate were significantly higher than during construction, although there was continuous rain. The aromatic group constituted > 50% of the VOC concentration totals and contributed >70% of OFP.

Volatile organic compounds in pesticide formulations: Methods to estimate ozone formation potential

The environmental fate and toxicity of active ingredients in pesticide formulations has been investigated for many decades, but relatively little research has been conducted on the fate of pesticide co-formulants or inerts. Some co-formulants are volatile organic compounds (VOCs) and can contribute to ground-level ozone pollution. Effective product assessment methods are required to reduce emissions of the most reactive VOCs. Six emulsifiable concentrate pesticide products were characterized for percent VOC by thermogravimetric analysis (TGA) and gas chromatography–mass spectrometry (GC–MS). TGA estimates exceeded GC–MS by 10–50% in all but one product, indicating that for some products a fraction of active ingredient is released during TGA or that VOC contribution was underestimated by GC–MS. VOC profiles were examined using TGA–Fourier transform infrared (FTIR) evolved gas analysis and were compared to GC–MS results. The TGA–FTIR method worked best for products with the simplest and most volatile formulations, but could be developed into an effective product screening tool. An ozone formation potential (OFP) for each product was calculated using the chemical composition from GC–MS and published maximum incremental reactivity (MIR) values. OFP values ranged from 0.1 to 3.1 g ozone g−1 product. A 24-h VOC emission simulation was developed for each product assuming a constant emission rate calculated from an equation relating maximum flux rate to vapor pressure. Results indicate 100% VOC loss for some products within a few hours, while other products containing less volatile components will remain in the field for several days after application. An alternate method to calculate a product OFP was investigated utilizing the fraction of the total mass of each chemical emitted at the end of the 24-h simulation. The ideal assessment approach will include: 1) unambiguous chemical composition information; 2) flexible simulation models to estimate emissions under different management practices; and 3) accurate reactivity predictions.

Comparative study of regulated and unregulated gaseous emissions during NEDC in a light-duty diesel engine fuelled with Fischer Tropsch and biodiesel fuels

Abstract In this study, regulated and unregulated gaseous emissions and fuel consumption with five different fuels were tested in a 4-cylinder, light-duty diesel EURO IV typically used for the automotive vehicles in Europe. Three different biodiesel fuels obtained from soybean oil, rapeseed oil and palm oil, a Fischer Tropsch fuel and an ultra low sulphur diesel were studied. The test used was the New European Driving Cycle (NEDC), this allowed tests to be carried out on an engine warmed up beforehand to avoid the effect of cold starts and several tests a day. Regulated emissions of NOX, CO, HC and CO2 were measured for each fuel. Unburned Hydrocarbon Speciation and formaldehyde were also measured in order to determine the maximum incremental reactivity (MIR) of the gaseous emissions. Pollutants were measured without the diesel oxidation catalyst (DOC) to gather data about raw emissions. When biodiesel was used, increases in regulated and unregulated emissions were observed and also significant increases in engine fuel consumption. The use of Fischer Tropsch fuel, however, caused lower regulated and unregulated emissions and fuel consumption than diesel.

Characteristics and source apportionment of VOCs measured in Shanghai, China

Volatile organic compounds (VOCs) were measured from 2007 to 2010 at the center of Shanghai, China. Because VOCs are important precursors for ozone photochemical formation, detailed information of VOC sources needs to be investigated. The results show that the measured VOC concentrations in Shanghai are dominated by alkanes (43%) and aromatics (30%), following by halo-hydrocarbons (14%) and alkenes (6%). Based on the measured VOC concentrations, a receptor model (PMF; positive matrix factorization) coupled with the information related to VOC sources (the distribution of major industrial complex, meteorological conditions, etc.) is applied to identify the major VOC sources in Shanghai. The result shows that seven major VOC sources are identified by the PMF method, including (1) vehicle related source which contributes to 25% of the measured VOC concentrations, (2) solvent based industrial source to 17%, (3) fuel evaporation to 15%, (4) paint solvent usage to 15%, (5) steel related industrial production to 12%, (6) biomass/biofuel burning to 9%, and (7) coal burning to 7%. Furthermore, ozone formation potential related to VOC sources is calculated by the MIR (maximum incremental reactivity) technique. The most significant VOC source for ozone formation potential is solvent based industrial sources (27%), paint solvent usage (24%), vehicle related emissions (17%), steel related industrial productions (14%), fuel evaporations (9%), coal burning (6%), and biomass/biofuel burning (3%). The weekend effect on the VOC concentrations shows that VOC concentrations are generally higher in the weekdays than in the weekends at the sampling site, suggesting that traffic conditions and human activities have important impacts on the VOC emissions in Shanghai.

Apportioning and Locating Nonmethane Hydrocarbon Sources to a Background Site in Korea

Nonmethane hydrocarbons (NMHCs) measured between April 2004 and March 2005 at a background monitoring site on Sukmo Island, Korea were analyzed to identify and apportion NMHC sources. A total of 7694 samples and 35 NMHC species were analyzed. Positive matrix factorization (PMF), applied to identify and apportion the sources of NMHCs, resolved six sources: two fuel evaporative sources (36.3%), solvent sources (25.4%), mixed sources of vehicle exhaust and combustion (22.8%), petrochemical sources (9.6%), and biogenic sources (5.4%). During the summer, the largest contributors to ozone formation were biogenic sources (48.9% and 79.7% by maximum incremental reactivity and propene-equivalent concentration, respectively), which were situated locally, and secondary sources included solvent sources (22.2% and 7.4%) and fuel evaporative sources (15.6% and 8.2%). For evaporative-1 sources composed of long-lived alkanes, the potential source contribution function (PSCF) technique using 48 h back trajectories revealed oil and gas fields in China as potential source areas of fresh "regional" air masses. In addition, the PSCF results for evaporative-2 sources and a long-lived marker species of vehicle exhaust/combustion sources showed that the NMHC mixing ratio in Sukmo, South Korea was enhanced by long-range transport from the Shandong area in China.

Ambient formaldehyde and its contributing factor to ozone and OH radical in a rural area

Formaldehyde (HCHO), as well as correlative pollutants was measured from 1 to 31 July in 2007 at Mazhuang, a rural site located in the east of China. Gaseous HCHO was scrubbed from the air with an acidic 2,4-dinitrophenylhydrazine (DNPH) solution, which leaded to the reaction of HCHO with DNPH and produced a stable product, 2,4-dinitrophenylhydrazone, followed by online analysis by high-performance liquid chromatography (HPLC) coupled with Ultraviolet detector. During the observation period, mixing ratios of HCHO ranged from 0.2 ppbv to 6.2 ppbv, with an average of 1.5 ± 0.67 ppbv. HCHO shows an evident diurnal variation, the maximum appeared during 12:00–14:00. The average concentration diurnal variations of measured HCHO, ozone (O 3), Methylhydroperoxides (MHP, CH 3OOH), hydrogen peroxide (H 2O 2), nitrogen oxides (NO x) and meteorological parameters were compared. The similar variations of HCHO, O 3 and radiation imply that photo-oxidation of hydrocarbons might be the major source for HCHO. Based on the maximum incremental reactivity (MIR) coefficient of HCHO, the calculation shows that HCHO contributes about 20% to total observed O 3 during the study period. In order to compare the contributions of O 3, HCHO and HONO to OH radical, photolysis rate parameters ( J-values) of the three compounds were calculated by the Tropospheric Ultraviolet and Visible (TUV) Radiation Model (4.4 version). Based on the comparison, this study reaches the conclusion that O 3 is the dominant source of OH radical at Mazhuang. This study also uses P(HCHO)/P(O 3) which represents the ratio of contrbutions of HCHO and O 3 to OH radical, to discuss the action of HCHO in OH radical soucers. The result shows that P(HCHO)/P(O 3) is 12.5% on average, with the maximum of 21.0% at 13:00 P.M. and minimum of 7.5% before 9:00 A.M. and after 17:00 P.M..Therefore HCHO is also an important source of OH radical and cannot be ignored.