Combustion-driven inorganic nitrogen in PM from a city in central China has the potential to enhance the nitrogen load of North China.

Inorganic nitrogen (NH and NO) is a significant component of PM, influencing not only regional ecological systems but also on other regions through the migration of air masses. However, few studies have simultaneously investigated the sources of NH and NO, and their potential transport pathways remain poorly understood. Here, daily PM samples were collected in Jiaozuo, a key city in the air pollution transmission channel to the north China, from 1 September to 5 December, 2017.

Thermal degradation of 18 amino acids during pyrolytic processes.

Biomass pyrolysis greatly impacts climates, ecosystem dynamics, air quality, human health, global carbon and nitrogen cycle. The emissions of nitrogen-containing compounds from biomass pyrolysis highly depend on the protein nitrogen existing in biomass. However, the quantitative kinetic information, including the rate constant and apparent activation energy of individual amino acid induced by pyrolysis are still yet to be well-constrained.

Stable carbon isotope reveals high impact of fishing ship activities on total carbon from PM in Qingdao, China.

Although total carbon (TC) is an important component of fine particulate matter (PM: particulate matter with aerodynamic diameter of <2.5 μm); its sources remain partially unidentified, especially in coastal urban areas. With ongoing development of the global economy and maritime activities, ship-generated TC emissions in port areas cannot be neglected.

Dual isotope analysis reveals the COVID-19 lockdown impact on nitrate aerosol sources and formation pathways in Shanghai.

Nitrate (NO) is an important contributor to PM which can adversely affect the environment and human health. A noticeable decrease in NO concentrations has been reported due to the lockdown measures implemented to curb the spread of Corona Virus Disease 2019 (COVID-19). However, questions remain, regarding the nonlinear relationship between NO and NO.

Kinetic nitrogen isotope effects of 18 amino acids degradation during burning processes.

Understanding the nitrogen isotopic variations of individual amino acids (AAs) is essential for utilizing the nitrogen isotope values of individual amino acids (δN-AA) as source indicators to identify proteinaceous matter originating from biomass combustion processes. However, the nitrogen isotope effects (ε) associated with the degradation of individual amino acids during combustion processes have not been previously explored. In this study, we measured the nitrogen isotope values of residual free amino acids -following a series of controlled combustion experiments at temperatures of 160-240 °C and durations of 2 min to 8 h, as described in Part 1.

Characterizing leaf-deposited particles: Single-particle mass spectral analysis and comparison with naturally fallen particles.

The size and composition of particulate matter (PM) are pivotal in determining its adverse health effects. It is important to understand PM's retention by plants to facilitate its atmospheric removal. However, the distinctions between the size and composition of naturally fallen PM (NFPM) and leaf-deposited PM (LDPM) are not well-documented.

Pollution characteristics, sources, and health risks of phthalate esters in ambient air: A daily continuous monitoring study in the central Chinese city of Nanchang.

In recent years, the atmospheric pollution caused by phthalate esters (PAEs) has been increasing due to the widespread use of PAE-containing materials. Existing research on atmospheric PAEs lacks long-term continuous observation and samples from cities in central China. To investigate the pollution characteristics, sources, and health risks of PAEs in the ambient air of a typical city in central China, daily PM samples were collected in Nanchang from November 2020 to October 2021.

Sources and influences of atmospheric nonpolar organic compounds in Nanchang, central China: Full-year monitoring with a focus on winter pollution episodes.

Nonpolar organic compounds (NPOCs) are found in atmospheric aerosols and have significant implications for environmental and human health. Although many studies have quantitatively estimated the sources of NPOCs in different cities, few have evaluated their main influencing factors (e.g.

Multiphase interactions between sulfur dioxide and secondary organic aerosol from the photooxidation of toluene: Reactivity and sulfate formation.

There is growing evidence that the interactions between sulfur dioxide (SO) and organic peroxides (POs) in aerosol and clouds play an important role in atmospheric sulfate formation and aerosol aging, yet the reactivity of POs arising from anthropogenic precursors toward SO remains unknown. In this study, we investigate the multiphase reactions of SO with secondary organic aerosol (SOA) formed from the photooxidation of toluene, a major type of anthropogenic SOA in the atmosphere. The reactive uptake coefficient of SO on toluene SOA was determined to be on the order of 10, depending strikingly on aerosol water content.

Multiphase Reactions between Organic Peroxides and Sulfur Dioxide in Internally Mixed Inorganic and Organic Particles: Key Roles of Particle Phase Separation and Acidity.

Organic peroxides (POs) are ubiquitous in the atmosphere and particularly reactive toward dissolved sulfur dioxide (SO), yet the reaction kinetics between POs and SO, especially in complex inorganic-organic mixed particles, remain poorly constrained. Here, we report the first investigation of the multiphase reactions between SO and POs in monoterpene-derived secondary organic aerosol internally mixed with different inorganic salts (ammonium sulfate, ammonium bisulfate, or sodium nitrate). We find that when the particles are phase-separated, the PO-S(IV) reactivity is consistent with that measured in pure SOA and depends markedly on the water content in the organic shell.

Enhanced aerosols over the southeastern Tibetan Plateau induced by open biomass burning in spring 2020.

The Tibetan Plateau is the third pole of the world, with an essential role in regulating Northern Hemisphere climate. Previous studies showed that atmospheric aerosols over the Tibetan Plateau are influenced by biomass burning (BB) products from South and Southeast Asia. In fact, open biomass burning (OBB) is also an important form of BB in Southeast Asian countries, causing serious springtime air pollution yearly.

Acylperoxy Radicals as Key Intermediates in the Formation of Dimeric Compounds in α-Pinene Secondary Organic Aerosol.

High molecular weight dimeric compounds constitute a significant fraction of secondary organic aerosol (SOA) and have profound impacts on the properties and lifecycle of particles in the atmosphere. Although different formation mechanisms involving reactive intermediates and/or closed-shell monomeric species have been proposed for the particle-phase dimers, their relative importance remains in debate. Here, we report unambiguous experimental evidence of the important role of acyl organic peroxy radicals (RO) and a small but non-negligible contribution from stabilized Criegee intermediates (SCIs) in the formation of particle-phase dimers during ozonolysis of α-pinene, one of the most important precursors for biogenic SOA.

Isomer-Resolved Reactivity of Organic Peroxides in Monoterpene-Derived Secondary Organic Aerosol.

Organic peroxides play a vital role in the formation, evolution, and health impacts of atmospheric aerosols, yet their molecular composition and fate in the particle phase remain poorly understood. Here, we identified, using iodometry-assisted liquid chromatography mass spectrometry, a large suite of isomer-resolved peroxide monomers (CHO) and dimers (CHO) in secondary organic aerosol formed from ozonolysis of the most abundant monoterpene (α-pinene). Combining aerosol isothermal evaporation experiments and multilayer kinetic modeling, bulk peroxides were found to undergo rapid particle-phase chemical transformation with an average lifetime of several hours under humid conditions, while the individual peroxides decompose on timescales of half an hour to a few days.

The use of stable oxygen and nitrogen isotopic signatures to reveal variations in the nitrate formation pathways and sources in different seasons and regions in China.

Nitrate (NO) is one of the most important inorganic ions in fine particulate (PM) and drives regional haze formation; however, the NO sources and formation mechanisms in different seasons and regions are still debated. Here, PM samples were collected from Kunming and Nanning in southwestern China from September 1, 2017, to February 28, 2018 (spanning warm and cold months). We measured the daily O and N isotopic compositions of NO (δO-NO and δN-NO), estimated the δO-HNO values produced by different oxidation pathways, and quantified the NO formation pathways based on the isotope mass-balance equation.

Evaluation of black carbon source apportionment based on one year's daily observations in Beijing.

Combustion-derived black carbon (BC) is increasingly recognized as a significant pollutant that can have adverse effects on the atmospheric environment, human health, and regional climate. Fossil fuel combustion is the main source of BC, yet understanding of the relative contributions to BC from coal and liquid fuel combustion remains incomplete. Moreover, few studies have assessed the relative contributions based on long-term continuous daily field observations.

The impacts of reservoirs on the sources and transport of riverine organic carbon in the karst area: A multi-tracer study.

Reservoirs have been constructed as clean energy sources in recent decades with various environmental impacts. Karst rivers typically exhibit high dissolved inorganic carbon (DIC) concentrations, whether and how reservoirs affect carbon cycling, especially organic carbon (OC)-related biogeochemical processes in karst rivers, are unclear. To fill this knowledge gap, multiple tracer methods (including fluorescence excitation-emission matrix (EEM), ultraviolet (UV) absorption, and stable carbon (δC) and radiocarbon (ΔC) isotopes) were utilized to track composition and property changes of both particulate OC (POC) and dissolved OC (DOC) along river-transition-reservoir transects in the Southwest China karst area.

Oxidation and sources of atmospheric NOx during winter in Beijing based on δO-δN space of particulate nitrate.

The determination of both stable nitrogen (δN-NO) and stable oxygen (δO-NO) isotopic signatures of nitrate in PM has shown potential for an approach of assessing the sources and oxidation pathways of atmospheric NOx (NO+NO). In the present study, daily PM samples were collected in the megacity of Beijing, China during the winter of 2017-2018, and this new approach was used to reveal the origin and oxidation pathways of atmospheric NOx. Specifically, the potential of field δN-NO signatures for determining the NOx oxidation chemistry was explored.

Seasonal variation of nitrogen biogeochemical processes constrained by nitrate dual isotopes in cascade reservoirs, Southwestern China.

The increase of affected river reaches by reservoirs has drastically disturbed the original hydrological conditions, and subsequently influenced the nutrient biogeochemistry in the aquatic system, particularly in the cascade reservoir system. To understand the seasonal variation of nitrogen (N) behaviors in cascade reservoirs, hydrochemistry and nitrate dual isotopes (δN-NO and δO-NO) were conducted in a karst watershed (Wujiang River) in southwest China. The results showed that NO-N accounted for almost 90% of the total dissolved nitrogen (TDN) concentration with high average concentration 3.

Isotopic source analysis of nitrogen-containing aerosol: A study of PM in Guiyang (SW, China).

The source of fine particulate matter (PM) has been a longstanding subject of debate, the nitrogen-15 isotope (δN) has been used to identify the major sources of atmospheric nitrogen. In this study, PM samples (n = 361) were collected from September 2017 to August 2018 in the urban area of Guiyang (SW, China), to investigate the chemical composition and potential sources of PM. The results showed an average PM of 33.

Changes in nitrate accumulation mechanisms as PM levels increase on the North China Plain: A perspective from the dual isotopic compositions of nitrate.

Nitrate (NO) has become recognized as the most important water-soluble ion in fine particulate (PM), and has been proposed as a driving factor for regional haze formation. However, nitrate formation mechanisms are still poorly understood. In this study, PM samples were collected from September 2017 to August 2018 in Shijiazhuang, a city located on the North China Plain, and NOconcentration, δO-NO and δN-NO values in PM were analyzed.

Methylmercury biomagnification in aquatic food webs of Poyang Lake, China: Insights from amino acid signatures.

As the dominant mercury species in fish, methylmercury (MeHg) biomagnifies during its trophic transfer through aquatic food webs. MeHg is known to bind to cysteine, forming the complex of MeHg-cysteine. However, relationship between MeHg and cysteine in large-scale food webs has not been explored and contrasted with MeHg biomagnification models.

Enhanced biomass burning as a source of aerosol ammonium over cities in central China in autumn.

Atmospheric ambient gaseous ammonia (NH), the most abundant alkaline gas, affects public health and climate change through its key role in the formation of secondary aerosols via reactions with acidic gases. Estimation of the contributions of ammonia sources is very challenging in the urban atmosphere. Stable nitrogen isotope ratio (δN) measurements have shown that urban aerosol NH and gaseous NH are derived from fossil fuel combustion-related (FF) sources, such as coal combustion, NH slip, and vehicle exhaust, and volatilization-related sources, such as agriculture and urban water volatilization.

Spatial variability of inhalable fungal communities in airborne PM across Nanchang, China.

Although fungi are ubiquitous in the atmosphere and have important effect on human health, their spatial variability about diversity and taxonomic composition, remain poorly understood. Considering the differences of environmental conditions, distinct airborne fungal communities were expected in the urban, suburban and forest areas. To test this hypothesis, PM samples were consecutively collected for 14 days across Nanchang, China.

Response of fine aerosol nitrate chemistry to Clean Air Action in winter Beijing: Insights from the oxygen isotope signatures.

The implementation of Clean Air Actions improved air quality in Beijing, and the mass loadings of PM and numerous gaseous precursors decreased considerably. However, concentrations of particulate nitrate (p-NO) changed slightly in wintertime aerosol and its mass fraction increased from 11.3% in 2013 to 29.