Obscured Contribution of Oxygenated Intermediate-Volatility Organic Compounds to Secondary Organic Aerosol Formation from Gasoline Vehicle Emissions.

Secondary organic aerosol (SOA) formation from gasoline vehicles spanning a wide range of emission types was investigated using an oxidation flow reactor (OFR) by conducting chassis dynamometer tests. Aided by advanced mass spectrometric techniques, SOA precursors, including volatile organic compounds (VOCs) and intermediate/semivolatile organic compounds (I/SVOCs), were comprehensively characterized. The reconstructed SOA produced from the speciated VOCs and I/SVOCs can explain 69% of the SOA measured downstream of an OFR upon 0.

Characteristics of typical intermediate and semi volatile organic compounds in Shanghai during China International Import Expo event.

To ensure good air quality during the China International Import Expo (CIIE) event, stringent emission-reduction measures were implemented in Shanghai. To assess the efficacy of these measures, this study measured typical categories of intermediate/semi volatile organic compounds (I/SVOCs), including alkanes (C-C n-alkanes and pristane), EPA-priority polycyclic aromatic hydrocarbons (PAHs), alkylnaphthalenes, benzothiazole (BTH) and chlorobenzenes (CBs), at an urban site of Shanghai before and during two CIIE events (2019 and 2020; non-CIIE versus CIIE). The average concentrations of alkanes and PAHs during both 2019 and 2020 CIIE events decreased by approximately 41% and 17%, respectively, compared to non-CIIE periods.

Enigma of Urban Gaseous Oxygenated Organic Molecules: Precursor Type, Role of NO, and Degree of Oxygenation.

Oxidation of volatile organic compounds (VOCs) forms oxygenated organic molecules (OOMs), which contribute to secondary pollution. Herein, we present measurement results of OOMs using chemical ionization mass spectrometry with nitrate as the reagent ion in Shanghai. Compared to those in forests and laboratory studies, OOMs detected at this urban site were of relatively lower degree of oxygenation.

Fate of Oxygenated Volatile Organic Compounds in the Yangtze River Delta Region: Source Contributions and Impacts on the Atmospheric Oxidation Capacity.

The Community Multiscale Air Quality model (CMAQv5.2) was implemented to investigate the sources and sinks of oxygenated volatile organic compounds (OVOCs) during a high O and high PM season in the Yangtze River Delta (YRD) region, based on constraints from observations. The model tends to overpredict non-oxygenated VOCs and underpredict OVOCs, which has been improved with adjusted emissions of all VOCs.

An online method for monitoring atmospheric intermediate volatile organic compounds with a thermal desorption-gas chromatography/mass spectrometry.

As one of important precursors of secondary organic aerosol (SOA), intermediate volatile organic compounds (IVOCs) have attracted much attention in recent years. Most of the previous studies however largely focused on characteristics of IVOCs from different emission sources, while data from field observations to study their temporal variations was limited for lacking the sufficient time resolution monitoring data. In this study, an online thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) method was developed to generate monitor data with a three-hour time resolution for gaseous atmospheric IVOCs.

Field Detection of Highly Oxygenated Organic Molecules in Shanghai by Chemical Ionization-Orbitrap.

Secondary organic aerosol, formed through atmospheric oxidation processes, plays an important role in affecting climate and human health. In this study, we conducted a comprehensive campaign in the megacity of Shanghai during the 2019 International Import Expo (EXPO), with the first deployment of a chemical ionization─Orbitrap mass spectrometer for ambient measurements. With the ultrahigh mass resolving power of the Orbitrap mass analyzer (up to 140,000 Th/Th) and capability in dealing with massive spectral data sets by positive matrix factorization, we were able to identify the major gas-phase oxidation processes leading to the formation of oxygenated organic molecules (OOM) in Shanghai.

Intermediate volatile organic compounds emissions from vehicles under real world conditions.

Real-world vehicle emission factors (EFs) for the total intermediate volatile organic compounds (total-IVOCs) and volatile organic compounds (VOCs) from mixed fleets of vehicles were quantified in the Yangtze tunnel in Shanghai. Relationships of EFs of IVOCs with fleet compositions and vehicle speed as well as secondary organic formation potentials (SOAFPs) from IVOCs and VOCs were studied. Multiple linear regression (MLR) was used to estimate EFs of total-IVOCs for gasoline and diesel vehicles.

[Characteristics and Reactivity of Ambient VOCs in Urban Hangzhou, China].

The ambient concentration of 122 volatile organic compound (VOC) species were continuously measured in urban Hangzhou, China from May 2018 to April 2019. The average mixing ratio of VOCs was (59.4±23.

[Source Apportionment of Ambient Carbonyl Compounds Based on a PMF and Source Tracer Ratio Method: A Case Based on Observations in Nanjing].

Ambient carbonyl compounds play an important role in tropospheric atmospheric chemistry. Primary emissions and photochemical formation are both sources of carbonyls, and therefore it is challenging work to analyze their sources. In this study, carbonyl sources were apportioned using the source tracer ratio method (STR) and positive matrix factorization model (PMF) based on offline carbonyls observations at a site in Nanjing during March 2017.

Estimating Secondary Organic Aerosol Production from Toluene Photochemistry in a Megacity of China.

The production of secondary organic aerosols (SOA) from toluene photochemistry in Shanghai, a megacity of China, was estimated by two approaches, the parametrization method and the tracer-based method. The temporal profiles of toluene, together with other fifty-six volatile organic compounds (VOCs), were characterized. Combing with the vapor wall loss corrected SOA yields derived from chamber experiments, the estimated toluene SOA by the parametrization method as embodied in the two-product model contributes up to ∼40% of the total SOA budget during summertime.

[Chemical Compositions, Mass Concentrations, and Emission Factors of Particulate Organic Matters Emitted from Catering].

Catering is an important emission source of atmospheric particulate organic matters (POMs). Mass concentrations, chemical compositions, and emission factors of POMs emitted from catering were studied based on simulation experiments. The effects of different cooking methods, various ingredients, oils, and other factors were investigated.

Intermediate Volatility Organic Compound Emissions from a Large Cargo Vessel Operated under Real-World Conditions.

Intermediate volatility organic compound (IVOC) emissions from a large cargo vessel were characterized under real-world operating conditions using an on-board measurement system. Test ship fuel-based emission factors (EFs) of total IVOCs were determined for two fuel types and seven operating conditions. The average total IVOC EF was 1003 ± 581 mg·kg-fuel, approximately 0.

Emission factors of particulate and gaseous compounds from a large cargo vessel operated under real-world conditions.

On-board emissions measurements were performed on a Handysize-class bulk carrier operating under real-world conditions. Emission factors (EFs) were determined for criteria pollutants such as NO, CO, total hydrocarbons (THC), and PM; PM composition, including organic and elemental carbon (OC and EC), inorganic species, and a variety of organic compounds and VOC species (including alkanes, alkenes, single-ring aromatics, and oxygenated VOCs) were also analyzed. To investigate the impacts of engine type, fuel, and operating conditions on emissions, measurements were conducted on one main and one auxiliary engines using low- and high-sulfur fuels (LSF and HSF) under actual operating conditions, including at-berth, maneuvering, and cruising at different engine loads.

[Chemical Characterization, Spatial Distribution, and Source Identification of Organic Matter in PM in summertime Shanghai, China].

Particulate organic matter (POM) has attracted increasing attention recently due to its great contribution to fine particles (PM) and complex components and sources. In the present study, 78 particulate organic compounds in PM were quantified at three sites in Shanghai during summer; these sites were located in urban (Xuhui), suburban (Qingpu), and coastal (Lin'gang) areas of the city. Accordingly, the chemical composition and spatial distribution were investigated and sources were explored based on the indicators and diagnostic ratios combined with backward trajectory.

[Estimation of Fine Particle (PM) Emission Inventory from Cooking: Case Study for Shanghai].

Cooking is one of important emission sources of fine particles (PM). This study using the catering enterprises of Shanghai as an example, presents a method to estimate the PM emission inventory from cooking according to the number of stoves, cooking time, and number of customers. Based on in situ measurements, the concentrations of PM emissions ranged from 0.

[Volatile Organic Compounds(VOCs) Source Profiles of Industrial Processing and Solvent Use Emissions: A Review].

Industrial processing and solvent use are two most important industrial sources of volatile organic compounds (VOCs) in China, and the source profile study has attracted increasing attention recently. Studies of VOCs source profiles from industrial processing and solvent use since the year of 2000 were summarized in this study, focusing on the comparison among different studies and the potential impact of different research methods. In general, studies were very limited and focused on few sources.

[Quantification of the Influence of Industrial Emissions on Volatile Organic Compounds (VOCs) Using PMF Model: A Case Study of Jiangbei Industrial Zone in Nanjing].

Volatile organic compounds(VOCs)are important precursors of ozone and secondary organic aerosol. The effect of industrial emissions on ambient VOC concentrations in the Jiangbei Industrial Zone in Nanjing was evaluated using the ambient VOCs measurements taken at Nanjing University of Information Science and Technology (NUIST) during March 2017. The monitoring data showed that the sum of 92 measured VOCs (TVOCs) ranged from 10.

[Treatment Status and Emission Characteristics of Volatile Organic Compounds from Typical Industrial Sources].

The status of treatment equipment, the emission characteristics, and the ozone formation potential (OFP) of volatile organic compounds (VOCs) for 11 typical enterprises, which were categorized into the 8 major VOC emission industries identified by the emission inventory of a typical city in the Yangtze River Delta, are discussed in this paper. There was a large difference in the removal efficiency of non-methane hydrocarbon (NMHC) between different treatment techniques, and even an increase in concentration occurred after some of the treatments. The current treatment equipment for VOCs needs further optimization.

Volatile organic compounds (VOCs) source profiles of on-road vehicle emissions in China.

Volatile Organic Compounds (VOCs) source profiles of on-road vehicles were widely studied as their critical roles in VOCs source apportionment and abatement measures in megacities. Studies of VOCs source profiles from on-road motor vehicles from 2001 to 2016 were summarized in this study, with a focus on the comparisons among different studies and the potential impact of different factors. Generally, non-methane hydrocarbons dominated the source profile of on-road vehicle emissions.