Abstract:Cooking emission is an important unorganized source of volatile organic compounds (VOCs) in urban areas.VOCs from cooking is still a weak link in atmospheric environment research and management,due to the complexity of their emission characteristics.In this study,VOCs were sampled in restaurant kitchens and designed cooking experiments.Carbonyl compounds and whole air samples were collected by 2,4-dinitrophenylhydrazine (DNPH) and stainless steel canister,respectively.A total of 116 compounds were quantitatively analyzed by high performance liquid chromatography (HPLC) and gas chromatography (GC).The emission characteristics of VOCs from cooking were then analyzed and their influencing factors were investigated.In general,oxygenated VOCs (OVOCs) and alkanes were the main contributors to VOCs emitted from cooking,while the chemical source profiles of VOCs from different cooking sources showed significant discrepancies.In addition,we found that oil types,times of oil use,heating modes,cooking styles,and seasoning have significant impacts on cooking emission of VOCs.The ozone formation potential (OFP) of VOCs from different cuisines were then calculated.The most abundant components for OFP were formaldehyde,acetaldehyde,butyraldehyde,ethylene,and propylene.The results obtained in this study can supplement China's database of VOCs emitted from cooking.

Abstract:It is particularly important to clarify the correlation between fine particulate matter (PM_2.5) and O₃ (P-O) in account of the seemingly increasing surface ozone and decreasing PM_2.5 trends in China since 2014.Therefore,observations of hourly PM_2.5 and O₃ data for Beijing and Nanjing during 2014 to 2019 were summarized to reveal their P-O correlations.The observations showed a decreasing trend of annual average PM_2.5 mass concentration,which was -6.86 and -6.15 μg·m^-3·a^-1 for Beijing and Nanjing,respectively.While the annual maximum daily 8-hour average O₃ (MDA8 O₃) increased by 1.50 and 1.75 μg·m^-3·a^-1 for Beijing and Nanjing,respectively.O₃ pollution became more serious in summer for both cities.For Beijing,when O₃ mass concentration was below/above 100 μg·m^-3,the increase of O₃ concentration would correspond to the decrease/increase of PM_2.5 concentration,indicating a negative/positive P-O correlation.The same varying P-O correlation existed for Nanjing,except for the different critical value of O₃ mass concentration of 150 μg·m^-3.Significantly positive P-O correlation,indicated by Pearson correlation coefficient (COR) being larger than 0.5 on daily time scale,was found in both Beijing and Nanjing during May to September.While significantly negative P-O correlation,indicated by COR value being smaller than -0.5 on hourly time scale,was found for both Beijing and Nanjing during November to February.Compared with Nanjing,monthly and seasonal P-O correlation varied more greatly for Beijing.As for the diurnal variation,there was a significantly positive P-O correlation at 16:00 in summer and a weakly positive correlation during 13:00-17:00 in spring and autumn,and a significantly negative correlation at 08:00 in spring,autumn and winter.

Abstract:A total of 99 volatile organic compounds (VOCs) were measured using online Gas Chromatography Mass Spectrometer/Flame Ionization Detector (GC-MS/FID) at a rural site in Dezhou from November,2017 to January,2018.The VOCs composition,diurnal variation,sources,ozone formation potential (OFP),and secondary organic aerosol (SOA) yields were analyzed.The average volume fraction of total VOCs was (47.74±33.11)×10^-9,and alkanes were the most abundant VOCs species (40.66%).The diurnal variation of VOCs showed high concentration in morning and evening but low concentration at noon.Propane,propylene,benzene,methylbenzene,and dichloromethane were mainly from liquid petrol gas usage,biogenic sources,vehicle emissions,and solvent usage.Back trajectory model analysis showed that air mass from the north might contribute to VOCs concentration.The OFP of alkanes,alkenes,and aromatics were (34.87±33.60),(120.48±118.76),and (59.77±94.14) μg/m³,respectively;and ethylene,propylene,toluene,and m/p-xylene were the top 4 species which contributed most to OFP.The SOA formation was explored and aromatics,including toluene,m/p-xylene,and benzene,contributed most to SOA (93.7%).As a result,reducing aromatics emission will be an important way to control the ozone and PM_2.5 pollution in Dezhou.

Abstract:The ambient PM₁ levels during late autumn and winter season in Qingdao were monitored for two consecutive years (November 1st to next January 31st of 2017 and 2018).The carbon components of PM₁,and other atmospheric pollutants of PM₁₀,PM_2.5,SO₂,and NO₂,as well as correlated meteorological conditions,were used to trace the sources of ambient PM₁ in Qingdao.The results showed that the average daily concentrations of PM₁ were 40.58±25.98 μg/m³ and 42.55±25.05 μg/m³ for the two observation periods,which increased to 84.71±16.70 μg/m³ and 81.52±18.39 μg/m³ during haze episodes.The mass concentrations of OC and EC in PM₁ in haze days were 13.67±3.95 μg/m³ (16.48±6.34 μg/m³),3.95±1.02 μg/m³ (3.34±1.16 μg/m³) for year 2017(2018),respectively.While the SOC mass concentrations in haze days were 1.28 and 2.15 times of those in non-haze days for year of 2017 and 2018,suggesting the strong potential of secondary transformation of organic carbon during haze episodes.Three factors were apportioned through principal component analysis of carbon-containing components.Factor 1 has the largest explanatory variables,which were 58.98% and 67.14% for 2017 and 2018,indicating the carbon-containing components of PM₁ were mainly from sources of biomass combustion,coal burning,road dust,and gasoline vehicle exhaust.The backward airflow trajectory analysis showed that the air masses were mostly originated in Inner Mongolia and passed through Hebei,Tianjin,or other cities of Shandong and finally arrived at Qingdao.

Abstract:Air quality has always been a public concern,especially when regional air pollution episodes occurred in several typical regions of China,such as the Beijing-Tianjin-Hebei region,the Yangtze River Delta (YRD),and the Pearl River Delta.However,the decrease of fine particulate matter (PM_2.5) would somehow stimulate surface ozone production.Traditional air quality models usually use a simplified photochemical reaction mechanism to simulate the ozone concentration and its precursors with fitted kinetics and products based on chamber experiments,which leads to large discrepancies between model predictions and actual observations.To solve this problem,a near-explicit photochemical mechanism,the Master Chemical Mechanism (MCM) was implemented into the Community Multi-scale Air Quality model (CMAQ) to investigate a high ozone episode during August 27th to September 5th of 2015 over the YRD.The model can generally reproduce the temporal variation of ozone and its precursors in six representative cities.Statistical analysis of the maximum daily averaged 8-hour O₃ showed that both the normalized mean bias (NMB) and normalized mean error (NME) met the criteria,with the best performances in Xuzhou (NMB=-0.15 and NME=0.23).In the YRD,residential source contributed most to the total VOCs,accounting for 39.08%,followed by transportation (33.25%) and industry (25.56%).Power plants contributed least to the total VOCs for about 2.11%.Further analysis of reactive oxidized nitrogen (NO_y),which is the reservoirs of NO_x,indicated that its majority was NO_x (80%),followed by the nitric acid (HNO₃< 10%) in the YRD.The spatial distribution of O₃ was very similar to those of NO_y and NO_x.The distributions of other oxidized products,such as HCHO was similar to that of NO_x,perhaps due to the production by VOCs oxidation under high NO_x conditions.Methyl vinyl ketone (MVK) and methacrolein (MACR) were possibly formed by oxidation of biogenic VOCs,estimated from their similar spatial distributions with that of the BVOCs.The air pollutants in the YRD is affected by strong interactions between anthropogenic and biogenic emissions.

Abstract:Volatile organic compounds (VOCs) are important precursors of ozone and atmospheric particulate matters.In this study,98 VOCs were measured by online Gas Chromatography-Mass Spectrometer (Online GC-MS) from May to June in 2018 at a regional site in Taizhou,Jiangsu province.The compositions and diurnal variations of VOCs in Taizhou were analyzed,followed by a parameterization approach to calculate primary emissions and secondary formation of aldehydes and ketones.Source apportionment was conducted using the EPA Positive Matrix Factorization (PMF 5.0),while the Ozone Formation Potential (OFP) was calculated using the Maximum Incremental Reactivity (MIR).The results indicated that alkanes accounted for the highest proportion of VOCs in Taizhou,followed by aldehydes and ketones.The diurnal profiles of alkanes,alkenes,halogenated hydrocarbon,and aromatics were similar.The parameterization method demonstrated that aldehydes mainly came from secondary formation,while ketones mainly came from primary emission.PMF model results showed that VOCs in Taizhou were mainly influenced by vehicle emission,solvent volatilization,biomass combustion,and other industrial or natural sources.OFP results indicated that alkenes were predominant,accounting for 34.18% of the total ozone formation potential.As a result,measures of reducing industrial emissions and the use of solvent will play an important role in air pollutant control strategies of Taizhou.

Abstract:Emission inventories of air pollutants are important inputs for air quality models.This study compared two emission inventories for Jiangsu province,referred to as YRD emission inventory and JS emission inventory,compiled by Shanghai Academy of Environmental Sciences and Jiangsu Academy of Environmental Sciences,respectively.The impacts of emission inputs on simulated PM_2.5 and O₃ in the Yangtze River Delta (YRD) in January,April,July,and October of 2017 were assessed with the community multiscale air quality (CMAQ) model.The emission estimates of various pollutants (except SO₂) by JS emission inventory are lower than those by YRD emission inventory.Both the emission inventories can reproduce observations of SO₂,NO_x,O₃,and PM_2.5 with CMAQ.While the simulated PM_2.5 and O₃ with the two emission inputs are similar in spatial distributions and seasonal variations,PM_2.5 and O₃ with JS emission inventory are lower than those with YRD emission inventory mostly in the YRD region (except O₃ in January).This work shows that both of the emission inventories are good enough for air quality modeling,and to inform policy decision on control of fine particulate matter and photochemical smog pollution in Jiangsu province.

Abstract:We analyzed the characteristics of volatile organic compounds (VOCs) and their key active components in Jiangsu province using the VOCs data monitored in urban areas of Jiangsu's 13 cities from August 13th to September 30th,2019.The results showed that the daily concentration of VOCs in Jiangsu ranged from 8.83×10^-9 to 45.11×10^-9,with alkanes being dominant and followed by aromatics,alkenes,and alkynes.The concentration of VOCs in 13 cities ranged from 7.85×10^-9 to 30.52×10^-9,which was highest in Xuzhou due to the location of its monitoring station as well as its industrial structure.When the ambient ozone concentration was excellent,good,light pollution,and moderate pollution,the total VOCs were 14.96×10^-9,17.96×10^-9,25.85×10^-9,and 25.11×10^-9,respectively.On the whole,the VOCs concentration was higher when the ozone was in pollution level,and the proportion of alkyne in VOCs increased with the aggravation of ozone pollution,indicating the close relation between ozone generation and human activities.Species including m/p-xylene,ethylene,toluene,propylene,isoprene and o-xylene,were screened out by weighting,which were the key species that had large and extensive impact on ambient VOCs of Jiangsu province.

Abstract:Peroxyacetyl nitrate (PAN) is a typical secondary product of VOCs and NO_x photochemical reaction,and a better indicator of photochemical smog than O₃.The ambient levels of PAN in Jinhua from June to October,2019 were measured by online instrument,and the PAN variation and correlated influencing factors,as well as one typical photochemical pollution episode were analyzed.The results showed that the average volume fraction of PAN was 0.656×10^-9,with maximum value recorded as 4.348×10^-9.Daily averaged PAN volume fractions were ranged from 0.130×10^-9 to 2.203×10^-9.The diurnal variation of PAN was a double-peak pattern in September and a single-peak one in other months.The ambient PAN level in summer was generally lower than that in autumn due to the meteorological influences.During the typical pollution episode from September 27th to September 30th,the hourly mean PAN volume fraction was 2.8 times of that during the whole observation period,and the pollution was dominated by local accumulation.The difference of precursor concentration and removal mechanism were important factors affecting the correlation between PAN and O₃,in addition,the ratio of NO/NO₂ was an important factor affecting the PAN formation rate,and the peak PAN values appeared during time with low ratio of NO/NO₂.Propane,ethane and m,p-xylene were the most important VOCs precursors of PAN.

Abstract:In recent years,ozone (O₃) pollution has become increasingly severe,which has proved to be the bottleneck of air quality control in Wuhan.Clarifying the nonlinear relationship between ozone and its precursors is the basis for ozone pollution control.To address this,an observation-based model was used to calculate relative incremental reactivity (RIR) and ozone formation potential based on online observation data of O₃ and its precursors collected by Wuhan city station during April to September 2018.The results showed that O₃ possessed obvious temporal variation on both seasonal and diurnal scales,and was subject to O₃ precursors as well as meteorological conditions.The average volume fraction of volatile organic compounds (VOCs) was 32.5×10^-9 during the observation period.Alkanes were the dominant VOCs in Wuhan,followed by oxygenated VOCs (OVOCs) and halogenated hydrocarbons.The reductions of VOCs and NO_x would respectively result in a significant drop and an increase of ozone formation potential.It indicated that Wuhan was under the VOCs-limited regime during the observation period.Among the anthropogenic VOCs,m/p-xylene and o-xylene had the highest RIR,thus were the major components affecting the formation of ambient ozone in Wuhan.

Abstract:Surface ozone pollution has become a bottleneck affecting the continuous improvement of air quality in recent years.Based on online observation data of ozone and its precursors including volatile organic compounds (VOCs) and nitrogen oxides (NO_x) in Huzhou during August 23rd to September 23rd,2017,the pollution characteristics of ozone and its precursors were analyzed.Furthermore,source apportionment of VOCs and the formation mechanism of ozone were investigated using positive matrix factorization (PMF) and observation based model (OBM),respectively.The results showed that average volume fraction of VOCs in Huzhou was (24.78±9.10)×10^-9 during the observation period.Alkanes,oxygenated VOCs (OVOCs),and halogenated hydrocarbons accounted for highest proportion to total VOCs.During the period when ozone concentration did not exceed air quality standard,ozone formation was in VOCs-limited regime,while during ozone pollution days,O₃ formation was in transitional regime but still limited by VOCs.During O₃ pollution days,aromatic hydrocarbons,olefins,and OVOCs were the three largest contributors to ozone formation potential (OFP),with relative contributions of 39.6%,21.5%,and 19.4%,respectively.The top three key components for OFP were toluene,ethylene,and m,p-xylene.PMF source apportionment results showed that the VOCs in Huzhou during the observation period were from solvent use (27.0%),traffic emission (22.7%),background and transport (19.3%),industrial emission (16.9%),gasoline volatilization (7.7%),and biogenic emission (6.4%).During O₃ pollution episodes,traffic emission and solvent use were the two largest contributors to OFP,with relative contributions of 35.1% and 30.5%,respectively.Therefore,reduction in traffic emissions and solvent use is an effective way to control ozone pollution in Huzhou.

Abstract:Understanding the characteristics of volatile organic compounds (VOCs) emission from coating industry is important to formulate the prevention and control strategy of ozone (O₃) and PM_2.5 in Shandong province.In this work,the volatile organic compounds (VOCs) discharged from metal coating process are analyzed for Shandong's two food packaging factories.The results showed that the concentration of VOCs emitted by the two factories were similar,with variations ranged at 50-1 500 μg/m³.However,their VOCs compositions were different to some extent.The oxygenated volatile organic compounds (OVOCs) was dominant and accounted for 89.71% of total VOCs discharged by factory manufacturing both aluminum and tinplate cans (Factory 1); while the aromatic hydrocarbon (56.15%) instead of the OVOCs (32.32%) became the main component of total VOCs discharged by factory manufacturing only aluminum cans (Factory 2).The VOCs source profiles were also different between the two factories.Specifically,the ethanol was dominant for both Factory 1's internal (94.28%) and external (84.46%) coating processes,while the 2-butanone (24.33%) and toluene (36.40%) were the most important components for Factory 2's internal and external coating process,respectively.

Abstract:The pharmaceutical industry has attracted much concern due to its large use of organic solvents and emission of VOCs (volatile organic compounds).In this study,107 VOCs species from 3 kinds of pharmaceutical enterprises including chemical synthesis,biological fermentation,and traditional Chinese medicine are measured.The results showed that the total VOCs concentration was more than 20 mg/m³ for chemical synthesis and biological fermentation pharmaceutical enterprises,and was relatively small to be 902.66 μg/m³ for traditional Chinese medicine enterprise.Among the 107 VOCs species,the OVOCs (oxygenated volatile organic compounds) were dominant,which accounted for more than 75% of the VOCs discharged by pharmaceutical enterprises.Besides that,the proportion of halogenated hydrocarbon species was high for chemical synthesis pharmacy.Pharmaceutical methods,production process,collection and emission measures are important factors affecting VOCs composition.

Abstract:An air suction seed drainer was designed and simulated in order to improve the mechanization level of precision seeders applicable for small size grains such as Chinese cabbage seeds.Firstly,the performance of the seed metering device was acquired through tests using performance test-bench of JPS-12,based on which the optimal parameter combination was obtained.Then,the flow field distribution inside the air suction chamber under different vacuum degrees or rotating speeds was analyzed using computational fluid dynamics (CFD) and FLUENT software,and a seed shape model of Chinese cabbage was established based on discrete element method (DEM).Finally,the seed metering device simulation was carried out by a simplified model and grid meshing.The comparison between bench test and simulation result showed that the air suction seed drainer performed best when the rotating speed of seed metering tray is 20 r/min and the vacuum degree of air suction chamber is 2.2 kPa.