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Haze formation is a major problem for the fruit wine and beverage industry. Conventional clarification treatments can inhibit haze formation but also cause loss of flavor and commodity value. In this study, a new technology was developed for the selective removal of haze proteins from fruit wines by magnetic adsorbent material. The material is based on phosphorylated chitin (PCT)-coated magnetic nanoparticles (Fe 3 O 4), which can adsorb chitinase through hydrophobic interaction forces and hydrogen bonding, and its adsorption capacity reached 74.4 μg/mg. When Fe 3 O 4 @PCT was mixed with mulberry wine at the dosage of 0.06 % (W/V) and incubated at 35 °C for 8 h, the material could effectively inhibit the haze formation in mulberry wine by specifically removing chitinase. The material exhibited high selectivity for adsorbing chitinase, and the adsorption rates of polyphenols and anthocyanins in mulberry wine were only 5.09 % and 3.019 %, respectively. Compared with traditional clarifiers such as bentonite or chitin, the clarification of mulberry wine using Fe 3 O 4 @PCT as a mulberry wine clarifier can retain the volatile substances closely related to the aroma of the wine, such as vinyl acetate, ethyl 2-hydroxybutyrate, and ethyl benzoate, etc., maximizing the retention of the flavor components in mulberry wine. The material was also characterized by magnetic recovery and elution regeneration, making it an effective alternative to conventional clarification methods for fruit wines. In addition, this selective technology could be beneficial in other fields such as biotechnology. • A novel clarifier is prepared by phosphorylated chitin-coated Fe 3 O 4 nanoparticles. • The clarifier selectively adsorbs chitinase by hydrophobicity and hydrogen bonding. • The clarifier can effectively inhibit the haze formation in mulberry wine. • The clarifier has a low adsorption rate against polyphenols and anthocyanins. • The clarifier can retain volatile substances closely related to the aroma of wine. [ABSTRACT FROM AUTHOR]

• Mannoproteins-rich extracts from sequential fermentations improved wine protein stability. • In sequential fermentations a higher number of released proteins was found. • Most of the proteins were glucan hydrolase involved in the release of cell wall mannoproteins. • S. bacillaris proteins MKC7 and ENG1 were exclusively found in the sequential fermentations. • Aspartic proteinase MKC7 could be involved in degrading grape proteins. Wine protein haze formation is a problem due to grape proteins aggregation during wine storage. The cell wall components of wine yeasts, particularly high molecular weight mannoproteins, have a protective effect against haze formation, although their involvement remains poorly understood. This study aimed at characterizing glycosylated proteins released by Starmerella bacillaris and Saccharomyces cerevisiae during single and sequential fermentations in a synthetic must, and testing their impact on wine protein stability. Mannoproteins-rich extracts from sequential fermentations showed an increase in the low MW polysaccharide fraction and, when added to an unstable wine, had a greater effect on protein stability than S. cerevisiae extracts. Shotgun proteomics approaches revealed that the identified cell wall proteins exclusively found in sequential fermentations were produced by both S. bacillaris (MKC7, ENG1) and S. cerevisiae (Bgl2p). Moreover, sequential fermentations significantly increased the expression of Scw4p and 1,3-beta-glucanosyltransferase (GAS5), produced by S. cerevisiae. Finally, some of the key proteins identified might play a positive role in increasing wine protein stability. [ABSTRACT FROM AUTHOR]

Haze can appear in white wines as a result of the denaturation and subsequent aggregation of grape pathogenesis-related (PR) proteins. Yeast cell-wall polysaccharides, particularly mannoproteins, represent a promising strategy to reduce the incidence of this phenomenon. The aim of this study was to evaluate the effects of 13 Starmerella bacillaris strains, in sequential fermentation with Saccharomyces cerevisiae, on wine protein stability of three white wines (Sauvignon blanc, Pinot grigio, and Manzoni bianco). The resulting wines were characterized in terms of their chemical composition, content of PR proteins and polysaccharides, and heat stability. In addition, the mannoprotein fraction was purified from six wines, five produced with S. bacillaris and one with S. cerevisiae EC1118 used as control. Generally, wines produced with S. bacillaris strains were more heat-stable, despite generally containing higher amounts of PR proteins. The increased heat stability of Starmerella wines was attributed to the stabilizing effect resulting from their higher concentrations of both total polysaccharides and mannoprotein fractions. In particular, for the most heat unstable wine (Manzoni bianco), the low MW mannoprotein fraction resulted to be the most involved in wine stability. The ability to produce wines with different heat stability was demonstrated to be strain-dependent and was more evident in the most unstable wines. By reducing fining waste, the use of S. bacillaris as an enological starter can be proposed as a new tool to manage wine protein stability for a more sustainable winemaking.

The atmospheric oxidizing capacity is the most important driving force for the chemical transformation of pollutants in the atmosphere. Traditionally, the atmospheric oxidizing capacity mainly depends on the concentration of O 3 and other gaseous oxidants. However, the atmospheric oxidizing capacity based on gas-phase oxidation cannot accurately describe the explosive growth of secondary particulate matter under complex air pollution. From the chemical perspective, the atmospheric oxidizing capacity mainly comes from the activation of O 2 , which can be achieved in both gas-phase and interfacial processes. In the heterogeneous or multiphase formation pathways of secondary particulate matter, the enhancement of oxidizing capacity ascribed to the O 2 /H 2 O-involved interfacial oxidation and hydrolysis processes is an unrecognized source of atmospheric oxidizing capacity. Revealing the enhanced oxidizing capacity due to interfacial processes in high-concentration particulate matter environments and its contribution to the formation of secondary pollution are critical in understanding haze chemistry. The accurate evaluation of atmospheric oxidizing capacity ascribed to interfacial processes is also an important scientific basis for the implementation of PM 2.5 and O 3 collaborative control in China and around the world.

Secondary inorganic aerosols, including sulfate, nitrate, and ammonium contribute to a large extent to the severe haze pollution events in China. Understanding their formation mechanisms is critical for designing effective mitigation strategies to control haze pollution, especially as the role of nitrate seemed to become more important recently, especially in some megacities. In the present study, simultaneous observations were conducted in two megacities (Chengdu and Chongqing) in Sichuan Basin of southwest China, one of the regions suffering from severe aerosol pollution. One typical long-lasting pollution event in Chengdu and Chongqing was captured during wintertime from December 25, 2016 to January 5, 2017. The campaign-average of hourly concentrations of PM 2.5 , sulfate, and nitrate, measured by an Aerosol Analyzer (ZSF) were 101 ± 73.8 μg/m3, 15.9 ± 11.8 μg/m3, and 24.9 ± 20.6 μg/m3, respectively, in Chengdu, and were 87.7 ± 53.8 μg/m3, 19.7 ± 13.5 μg/m3, and 15.1 ± 10.1 μg/m3, respectively, in Chongqing. Nitrate contributed substantially to PM 2.5 pollution when PM 2.5 was lower than 150 μg/m3, largely due to the strong secondary transformation of NO X to nitrate during the occurrence of the pollution episode. Heterogeneous hydrolysis of N 2 O 5 dominated nitrate formation during nighttime, while photochemical reactions and high-RH enhanced gas- to aqueous-phase dissolution of NH 3 and HNO 3 or cloud processes likely played important roles for nitrate formation during daytime. RH-dependent heterogeneous reactions contributed greatly to the formation of sulfate. NO X is confirmed to play an important role as an oxidant in accelerating the secondary transformation of SO 2 to sulfate at high RH and low O 3 levels under neutralization condition during heavy PM 2.5 pollution episode. Results from this study identified the formation mechanism of nitrate, especially during the daytime, and addressed the importance of heterogeneous inorganic reactions in the formation of heavy aerosol pollution events. Image 1 • Nitrate rather than sulfate largely drove the growth of PM 2.5 pollution in Sichuan Basin. • Photochemical oxidation had stronger influence on the formation of nitrate than sulfate. • NO X promoted the secondary transformation of SO 2 to sulfate during heavy PM 2.5 pollution episode. Nitrate rather than sulfate largely drove the growth of PM 2.5 pollution, due to the strong atmospheric photochemistry in daytime and high RH sustained nitrate growth at night. [ABSTRACT FROM AUTHOR]

Abstract Water-soluble organic acids are widely involved in various atmospheric physicochemical processes and appear as an important fraction of atmospheric aerosols. Nineteen water-soluble organic acids in 12-h PM 1 , PM 2.5 and PM 10 samples collected in urban Beijing during haze episodes in winter and spring of 2017 were identified to investigate their characteristics and secondary formation mechanism. The molecular distributions of water-soluble organic acids as well as the high ratio of phthalic acid (Ph)/azelaic acid (C 9) indicated severe aromatic secondary organic aerosol pollution during the haze episodes, especially in winter. The diurnal patterns, size distributions, and concentration ratios of specific organic acids were investigated to reveal the pollution characteristics and possible sources of major organic acids in particulate matter in Beijing during haze events. Multiple linear regression was used to tentatively quantify the relative contributions of photochemical oxidation and aqueous-phase oxidation to the formation of total water-soluble organic acids in PM 1 , PM 2.5 and PM 10 during haze episodes. The formation mechanism of sulfate and nitrate was also investigated for comparison. Different from the secondary formation of sulfate, the secondary formation of water-soluble organic acids showed enhanced contribution of gas-phase photochemical oxidation though the aqueous-phase oxidation was the dominant process. Capsule Molecular analyses of organic acids in PM 1 , PM 2.5 and PM 10 in Beijing during haze periods revealed their pollution characteristics, possible sources and formation mechanism. Graphical abstract Unlabelled Image Highlights • Aromatic SOA pollution was severe during haze episodes, especially in winter. • Photochemical oxidation was suppressed during haze episodes. • Aqueous-phase oxidation was the major formation pathway of organic acids. [ABSTRACT FROM AUTHOR]

Abstract Formation of haze is a phenomenon dependent on the relative atmospheric humidity and concentration of aerosol particles. The physical and chemical reactions on particle surfaces would lead to variations in particle sizes. This paper focuses on the physical behaviour of aerosol particles under the influence of atmospheric humidity, which produces liquid bridging forces and electrostatic interactions among particles. By water absorption experiment, a correlation between relative humidity (RH) and water content on particles was obtained. Through theoretical derivation, a relationship between the relative humidity and humidity ratio was established for calculating liquid bridging forces. The findings from experiments on atmospheric particles charging, showed most aerosols were negatively or positively charged and the average charges on these particles was more than one. An extended soft-sphere discrete element method (DEM) was used to simulate the evolution of aerosol particles, encapsulated in water vapour by considering liquid bridging forces, electrostatic interactions and Brownian forces. Results suggest that the agglomeration rate of particles would increase with a rise in the atmospheric humidity due to the increased liquid bridging forces that enhance the agglomeration velocity. The higher humidity would enhance the ionization on particle surfaces, which could affect electrostatic interactions. This paper provides an insight of a mechanism for formation of haze in atmosphere. Highlights • Extended DEM model is developed to show the size evolution of aerosol particles. • Liquid-bridge and electrical forces related to RH is present in our simulation. • Our experiment further indicates most particles charged negatively or positively. [ABSTRACT FROM AUTHOR]

Abstract: Ammonium sulfate (AS) and ammonium nitrate (AN) are key components of urban fine particles. Both field and model studies showed that heterogeneous reactions of SO2, NO2, and NH3 on wet aerosols accelerated the haze formation in northern China. However, little is known on phase transitions of AS‐AN containing haze particles. Here hygroscopic properties of laboratory‐generated AS‐AN particles and individual particles collected during haze events in an urban site were investigated using an individual particle hygroscopicity system. AS‐AN particles showed a two‐stage deliquescence at mutual deliquescence relative humidity (MDRH) and full deliquescence relative humidity (DRH) and three physical states: solid before MDRH, solid‐aqueous between MDRH and DRH, and aqueous after DRH. During hydration, urban haze particles displayed a solid core and aqueous shell at RH = 60–80% and aqueous phase at RH > 80%. Most particles were in aqueous phase at RH > 50% during dehydration. Our results show that AS content in individual particles determines their DRH and AN content determines their MDRH. AN content increase can reduce MDRH, which indicates occurrence of aqueous shell at lower RH. The humidity‐dependent phase transitions of nitrate‐abundant urban particles are important to provide reactive surfaces of secondary aerosol formation in the polluted air. [ABSTRACT FROM AUTHOR]

The construction of an experimental system that can mimic koji making in the manufacturing setting of a sake brewery is initially required for the quantitative evaluation of mycelia grown on/in koji pellets ( haze formation). Koji making with rice was investigated with a solid-state fermentation (SSF) system using a non-airflow box (NAB), which produced uniform conditions in the culture substrate with high reproducibility and allowed for the control of favorable conditions in the substrate during culture. The SSF system using NAB accurately reproduced koji making in a manufacturing setting. To evaluate haze formation during koji making, surfaces and cross sections of koji pellets obtained from koji making tests were observed using a digital microscope. Image analysis was used to distinguish between haze and non- haze sections of koji pellets, enabling the evaluation of haze formation in a batch by measuring the haze rate of a specific number of koji pellets. This method allowed us to obtain continuous and quantitative data on the time course of haze formation. Moreover, drying koji during the late stage of koji making was revealed to cause further penetration of mycelia into koji pellets (internal haze ). The koji making test with the SSF system using NAB and quantitative evaluation of haze formation in a batch by image analysis is a useful method for understanding the relations between haze formation and koji making conditions. [ABSTRACT FROM AUTHOR]

East Asian experiences frequent severe haze episodes (EPs) during winter–spring, and their causes are not fully understood. Two EPs (daily average PM 2.5 > 35 μg m−3) occurred at Tianjin (TJ), China, and Daejeon (DJ), Korea, during late February (EP-1) and early March (EP-2) 2019. The mean total PM 2.5 concentrations at the TJ and DJ sites during these events (82.9 and 66.2 μg m−3, respectively) were approximately three times higher than those observed during non-haze events (27.3 and 23.0 μg m−3, respectively). MODIS satellite RGB images suggested that aerosols were transported regionally from east Asian countries to the DJ site during EPs. After NO 3 −, the major contributors to PM 2.5 during the EPs at both sites were NH 4 +, SO 4 2−, and organic carbon (OC), indicating that secondary aerosols were important in severe haze formation. During the EPs, the distributions of secondary chemical species were similar at the two sites, with coefficient of divergence (COD) values of <0.2, whereas primary chemical species had dissimilar distributions with COD values of >0.2. This suggests that secondary aerosols may be impacted by regional influences, whereas primary aerosols are subject to more local influence. The average COD values in the first two days (27–28 February) relative to the remaining days (1–7 March) were <0.2 at the DJ site during EP-2, indicating no additional local production of secondary and primary species. Sulfur oxidation ratios (SOR) were lower at the TJ site than at the DJ site, while nitrogen oxidation ratios (NOR) were higher. Gradual increases observed in SOR and NOR at the TJ site early in the EPs imply significant secondary formation of SO 4 2− and NO 3 −. Strong correlations between aerosol liquid-water content (ALWC) and SOR and NOR at the TJ site indicate that aqueous-phase reactions were important in the formation of SO 4 2− and NO 3 −. Although high concentrations of SO 4 2− and NO 3 − were observed at the DJ site, correlations between ALWC and SOR/NOR were weak with low regression gradients, implying that SO 4 2− and NO 3 − may have been associated with regional transport. Low COD values, and SOR and NOR values similar to those at the beginning of EP-2, imply that additional formation of SO 4 2− or NO 3 − at the DJ site is not active, with stagnant atmospheric conditions prevailing. • Investigations of haze aerosol formation in two East Asian cities. • High concentration of NO3- was found during episodic events. • Secondary aerosols play a major role in the formation of haze episodes. • Aqueous-phase reactions play an important role in the formation of SO 4 2− and NO 3 − • Regional aerosol transport from Asia resulted in high SO 4 2− and NO 3 − levels. [ABSTRACT FROM AUTHOR]

We measured submicron aerosols (PM 1 ) at a beachfront site in Texas in Spring 2021 to characterize the "background" aerosol chemical composition advecting into Texas and the factors controlling this composition. Observations show that marine "background" aerosols from the Gulf of Mexico were highly processed and acidic; sulfate was the most abundant component (on average 57% of total PM 1 mass), followed by organic material (26%). These chemical characteristics are similar to those observed at other marine locations globally. However, Gulf "background" aerosols were much more polluted; the average non-refractory (NR-) PM 1 mass concentration was 3-70 times higher than that observed in other clean marine atmospheres. Anthropogenic shipping emissions over the Gulf of Mexico explain 78.3% of the total measured "background" sulfate in the Gulf air. We frequently observed haze pollution in the air mass from the Gulf, with significantly elevated concentrations of sulfate, organosulfates, and secondary organic aerosol associated with sulfuric acid. Analysis suggests that aqueous oxidation of shipping emissions over the Gulf of Mexico by peroxides in the particles might potentially be an important pathway for the rapid production of acidic sulfate and organosulfates during the haze episodes under acidic conditions.

Urban air quality in China has been declining substantially in recent years due to severe haze episodes. The reduction of sulfur dioxide (SO 2 ) and nitrogen oxide (NO x ) emissions since 2013 does not yet appear to yield substantial benefits for haze mitigation. As the reductions of those key precursors to secondary aerosol formation appears not to sufficient, other crucial factors need to be considered for the design of effective air pollution control strategies. Here we argue that ammonia (NH 3 ) plays a - so far - underestimated role in the formation of secondary inorganic aerosols, a main component of urban fine particulate matter (PM 2.5 ) concentrations in China. By analyzing in situ concentration data observed in major cities alongside gridded emission data obtained from remote sensing and inventories, we find that emissions of NH 3 have a more robust association with the spatiotemporal variation of PM 2.5 levels than emissions of SO 2 and NO x . As a consequence, we argue that urban PM 2.5 pollution in China in many locations is substantially affected by NH 3 emissions. We highlight that more efforts should be directed to the reduction of NH 3 emissions that help mitigate PM 2.5 pollution more efficiently than other PM 2.5 precursors. Such efforts will yield substantial co-benefits by improving nitrogen use efficiency in farming systems. As a consequence, such integrated strategies would not only improve urban air quality, but also contribute to China's food-security goals, prevent further biodiversity loss, reduce greenhouse gas emissions and lead to economic savings. [ABSTRACT FROM AUTHOR]

Polysaccharides are the major high-molecular weight components of wines. In contrast, proteins occur only in small amounts in wine, but contribute to haze formation. The detailed mechanism of aggregation of these proteins, especially in combination with other wine components, remains unclear. This study demonstrates the different aggregation behavior between a buffer and a model wine system by dynamic light scattering. Arabinogalactan-protein, for example, shows an increased aggregation in the model wine system, while in the buffer system a reducing effect is observed. Thus, we could show the importance to examine the behavior of wine additives under conditions close to reality, instead of simpler buffer systems. Additional experiments on melting points of wine proteins reveal that only some isoforms of thaumatin-like proteins and chitinases are involved in haze formation. We can confirm interactions between polysaccharides and proteins, but none of these polysaccharides is able to prevent haze in wine. [ABSTRACT FROM AUTHOR]

Flocculation plays a central role in the way beer is produced. The primary function of flocculation is particle removal that can impart color to beer, create turbidity, and/or retain bacterial organisms. This study was carried out to investigate if carbon chitin and chitosan can be used as heterogeneous flocculants in the treatment of beer. A series of experiments were conducted in which the efficiency of chitin and chitosan was compared with the efficiency of traditional stabifix and bentonite used by the industry in the flocculation process. Turbidity, viscosity, total solids, total suspended solids, total polyphenols and the zeta potential were used to monitor the progress of the flocculation process. Both chitin and chitosan demonstrated the ability to flocculate colloidal particles in the beer. Of all the tested flocculants, chitosan (5 mg/L) was found to be the most effective. [ABSTRACT FROM AUTHOR]

A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility < l0 km and RH (relative humidity) < 90%. Four haze episodes, which accounted for ~ 60% of the time during the whole campaign, were characterized by increases of SNA (sulfate, nitrate, and ammonium) and SOA (secondary organic aerosol) concentrations. The average values with standard deviation of SO42−, NO3−, NH4+ and SOA were 49.8 (± 31.6), 31.4 (± 22.3), 25.8 (± 16.6) and 8.9 (± 4.1) μg/m³, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO42−, NO3−, NH4+, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM10 during the non-haze days. The respective contributions of SNA species to PM10 rose to about 27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM10 mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR (sulfur oxidation ratio) and NOR (nitrogen oxidation ratio) increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO2 to SO42− and NO2 to NO3−, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing. [ABSTRACT FROM AUTHOR]

Highlights: [•] High pressure (HP) treatments modify the secondary structure of wine proteins. [•] HP treatment may contribute to stabilising proteins in Sauvignon blanc wine. [•] Modifications in protein structure and thermal stability depend on HP intensity. [•] Haze formation in wine during storage could be delayed by HP. [Copyright &y& Elsevier]

Beer is a complex mixture of over 450 constituents and, in addition, it contains macromolecules such as proteins, nucleic acids, polysaccharides, and lipids. In beer, several different protein groups, originating from barley, barley malt, and yeast, are known to influence beer quality. Some of them play a role in foam formation and mouthfeel, and others are known to form haze and have to be precipitated to guarantee haze stability, since turbidity gives a first visual impression of the quality of beer to the consumer. These proteins are derived from the malt used and are influenced, modified, and aggregated throughout the whole malting and brewing process. During malting, barley storage proteins are partially degraded by proteinases into amino acids and peptides that are critical for obtaining high-quality malt and therefore high-quality wort and beer. During mashing, proteins are solubilized and transferred into the produced wort. Throughout wort boiling proteins are glycated and coagulated being possible to separate those coagulated proteins from the wort as hot trub. In fermentation and maturation process, proteins aggregate as well, because of low pH, and can be separated. The understanding of beer protein also requires knowledge about the barley cultivar characteristics on barley/malt proteins, hordeins, protein Z, and LTP1. This review summarizes the protein composition and functions and the changes of malt proteins in beer during the malting and brewing process. Also methods for protein identification are described. [ABSTRACT FROM AUTHOR]

Beer is a complex mixture of over 450 constituents. In addition, it contains macromolecules such as proteins, nucleic acids, polysaccharides and lipids. Proteins influence the entire brewing process with regard to enzymes, which degrade starch, β-glucans and proteins; with protein-protein linkages that stabilize foam and are responsible for mouthfeel and flavour stability; and in combination with polyphenols, thought to form haze. With this complexity, problems in processability are as various as the constituents. Several substances in beer are responsible for haze formation. Organic components such as proteins, polyphenols and carbohydrates (α-glucans, β-glucans) are known to form haze. In addition, inorganic particles such as filter aids and label remains can cause increased turbidity. In this article only nonmicrobiological induced hazes are described. Many studies have been conducted on the identification of haze and foam active components in beer. Hence the aim of this work was to survey the different possibilities of haze formation and for haze identification. A summary is provided on methods for haze identification including dyeing methods, microscopic analyses and size exclusion chromatography. [ABSTRACT FROM AUTHOR]

Abstract: The chemical and physical properties of haze particles in the Dead Sea were measured using airborne and ground-based instruments. The results show a very distinct layering of the haze with two major layers, one below about 300m ASL and the other at around −150m ASL, which is around +250m above the Dead Sea surface. The lower layer was found to contain a large fraction of sodium nitrate particles with sizes larger than 1μm . The particles in this layer are likely transported at night from pollution sources to the south west of the Dead Sea. The upper layer contained large concentrations of fine sulfate particles that are transported from distance sources such as the Israeli Mediterranean coastal regions or even from sources as far away as Europe. The two haze layers appear to be separated in the morning hours, but as the day marches on and the temperature of the land surface on both sides of the lake increases, thermal convection sets in and the two layers become homogenized. A third layer around 1000m ASL is also observed. This layer is the commonly observed marine boundary layer over Israel and is not affected by the circulation in and around the Dead Sea. In the afternoon the Mediterranean sea breeze reaches the Dead Sea valley and is diverted first into a weak easterly and then into stronger northerly winds, which clear the haze particles from the valley. The land breeze over the lake during the night brings new pollution particles from the Rotem Plato to the southeast of the Dead Sea and is responsible for the formation of the early morning lower haze layer. [Copyright &y& Elsevier]

Aerosol growth potentials were investigated based on measurements of aerosol properties from three field campaigns carried out at sites in urban Beijing (BJ) and suburban Xingtai (XT) located in the North China Plain (NCP). BJ and XT were located in a northern megalopolis area and a central-southern industrial area, respectively, in the NCP. Results suggest new particle formation (NPF) events occurred more frequently, and the particle growth potential was greater in the central-southern NCP region than in the northern NCP region in summer. It is found that differences in primary emissions and meteorological conditions can cause regional and seasonal variations in aerosol growth potential in the NCP. Photochemical reactions were more important for particle growth in summer, while nocturnal aqueous chemical reactions were more important in winter. The large nocturnal particle growth rate (7.5 nm h−1) was the reason inducing the severe aerosol pollution in winter BJ. Further analyses of submicron aerosol chemical species indicate more sulfate in submicron aerosols at XT, suggesting that the growth of new particles in the central-southern NCP in summer may be mainly dominated by the secondary formation of inorganics. Diurnal variations in aerosol chemical species during the three field campaigns suggest that the downward vertical mixing of nitrate over the nocturnal boundary layer played an important role in aerosol growth in the morning in summer. Moreover, the enhanced anthropogenic emissions during the late-day rush hours can cause clear increases in nitrate and organics. Our results highlight the distinct aerosol growth potentials in the northern and central-southern areas of NCP, implying that different emission control measures are needed in two regions to further improve air quality in the future. ● Diverse aerosol growth potentials were found in different regions of the North China Plain. ● Different particle growth mechanisms in winter and summer were reported. ● Distinct emission control measures are needed in different regions of the North China Plain to further improve air quality in the future. [ABSTRACT FROM AUTHOR]

Haze pollution is inseparable from the transformation of air pollutants especially the ammonium and sulfate. Chemical and physical processes play important roles in this transformation. However, the role of microbial processes has rarely been studied. In this report, we applied the cultivation-independent metagenomic approach to study airborne microorganisms, investigating the potential microbial-catalyzed transformation of ammonium and sulfate in PM 2.5 samples. Functional genes predict that airborne microorganisms have the potential to catalyze ammonium formation but not ammonium oxidation since no ammoxidation genes were identified. We also found that the frequency of sulfate-forming genes was 1.56 times of those for sulfate-reducing genes. It was speculated that microbial metabolisms in the atmosphere could contribute to the accumulation of ammonium and sulfate. With the increase of PM 2.5 concentration, the frequency of functional genes and the relative abundance of genera which involved in nitrogen and sulfur metabolisms increased. That suggested air pollution was conducive to the microbial-mediated formation of ammonium and sulfate. Overall, our results provided evidence for the possible role of microbial processes in the air pollutant transformation and brought a new perspective for studying the formation of secondary air pollutants. Image 1 • Bioaerosols potentially catalyzed ammonium formation but not ammonium oxidation. • Bioaerosols preferred to mediate sulfate formation rather than sulfate oxidation. • PM 2.5 was correlated to the microbial-mediated formation of ammonium sulfate. Bioaerosols potentially mediated the haze pollution via the accumulation of ammonium and sulfate, which was the most severe in the heavily polluted air. [ABSTRACT FROM AUTHOR]

Atmospheric ammonia (NH 3) as the most important alkaline gas in the atmosphere has attracted much attention in recent years due to its critical role in haze formation, especially on the North China Plain (NCP). Comprehensive studies are needed for investigating diurnal variations of NH 3 and underlying mechanisms in different seasons and their potential impacts on atmospheric chemistry. In this study, continuous long-term observation (Mar. 2016 to May 2017) of NH 3 at a rural site in the NCP was used to characterize the diurnal variation of NH 3 in different seasons and to unveil its causes and potential impacts on atmospheric chemistry. NH 3 concentrations displayed rapid increases during the morning, reaching very prominent peaks mostly between 8:00 to 11:00 LT. Such frequent (55%) morning peaks were mainly caused by the evaporation of dew and guttation water droplets. Average dew and guttation water volume concentrations of 750 mL m−2 was estimated for spring, which resulted in approximate NH 3 emissions of 800 ng m−2 s− 1. Such high emission fluxes from dew and guttation water evaporation have never been reported before, suggesting dew and guttation droplets to be significant night-time reservoirs and strong morning sources for NH 3. In light of recent studies putting forward that NH 3 can promote the heterogeneous formation of HONO and nitrate under high humidity conditions, we investigated the differences in HONO and aerosol chemical composition diurnal variations between days with and without NH 3 morning spikes during November. HONO, nitrate and sulfate concentrations were significantly higher for days with NH 3 morning spikes, with HONO displaying a morning peak near that of NH 3. These results demonstrate that the prevailing NH 3 morning spikes on the NCP have significant influences on aerosol formation and atmospheric chemistry. NH 3 emission mitigation strategies and regulations are urgently needed. • Highly frequent morning peaks of NH 3 caused by dew and guttation water. • Dew and guttation water exhibit very high NH 3 storage and emission capacity. • NH 3 diurnal variation has potential impact on rapid haze formation. Dew and guttation water exhibit very high NH 3 storage and emission capacity, causing highly frequent NH 3 morning peaks, inducing rapid haze formation in the North China Plain. [ABSTRACT FROM AUTHOR]

Bentonite fining is the most popular treatment used to remove proteins in white and rosé wines. The usual heat test used to adjust the bentonite dose consists of heating the wine during 30 min at 80 °C. At this temperature, all of the proteins are unfolded, and this can lead to an overestimation of the dose. We have shown that proteins adsorb on bentonite in a specific order and, more importantly, that the proteins responsible for haze formation adsorb first. Fluorescence spectroscopy showed that this is due to the structural properties of proteins, which can be classified as hard and soft proteins. Alternative heat tests were performed at a lower temperature (40 °C) and showed a better correlation with accelerated aging. These tests were also less dependent upon the wine pH.

Atmospheric ammonia (NH 3 ) as the most important alkaline gas in the atmosphere has attracted much attention in recent years due to its critical role in haze formation, especially on the North China Plain (NCP). Comprehensive studies are needed for investigating diurnal variations of NH 3 and underlying mechanisms in different seasons and their potential impacts on atmospheric chemistry. In this study, continuous long-term observation (Mar. 2016 to May 2017) of NH 3 at a rural site in the NCP was used to characterize the diurnal variation of NH 3 in different seasons and to unveil its causes and potential impacts on atmospheric chemistry. NH 3 concentrations displayed rapid increases during the morning, reaching very prominent peaks mostly between 8:00 to 11:00 LT. Such frequent (55%) morning peaks were mainly caused by the evaporation of dew and guttation water droplets. Average dew and guttation water volume concentrations of 750 mL m -2 was estimated for spring, which resulted in approximate NH 3 emissions of 800 ng m -2 s - 1 . Such high emission fluxes from dew and guttation water evaporation have never been reported before, suggesting dew and guttation droplets to be significant night-time reservoirs and strong morning sources for NH 3 . In light of recent studies putting forward that NH 3 can promote the heterogeneous formation of HONO and nitrate under high humidity conditions, we investigated the differences in HONO and aerosol chemical composition diurnal variations between days with and without NH 3 morning spikes during November. HONO, nitrate and sulfate concentrations were significantly higher for days with NH 3 morning spikes, with HONO displaying a morning peak near that of NH 3 . These results demonstrate that the prevailing NH 3 morning spikes on the NCP have significant influences on aerosol formation and atmospheric chemistry. NH 3 emission mitigation strategies and regulations are urgently needed., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Urban air quality in China has been declining substantially in recent years due to severe haze episodes. The reduction of sulfur dioxide (SO 2 ) and nitrogen oxide (NO x ) emissions since 2013 does not yet appear to yield substantial benefits for haze mitigation. As the reductions of those key precursors to secondary aerosol formation appears not to sufficient, other crucial factors need to be considered for the design of effective air pollution control strategies. Here we argue that ammonia (NH 3 ) plays a - so far - underestimated role in the formation of secondary inorganic aerosols, a main component of urban fine particulate matter (PM 2.5 ) concentrations in China. By analyzing in situ concentration data observed in major cities alongside gridded emission data obtained from remote sensing and inventories, we find that emissions of NH 3 have a more robust association with the spatiotemporal variation of PM 2.5 levels than emissions of SO 2 and NO x . As a consequence, we argue that urban PM 2.5 pollution in China in many locations is substantially affected by NH 3 emissions. We highlight that more efforts should be directed to the reduction of NH 3 emissions that help mitigate PM 2.5 pollution more efficiently than other PM 2.5 precursors. Such efforts will yield substantial co-benefits by improving nitrogen use efficiency in farming systems. As a consequence, such integrated strategies would not only improve urban air quality, but also contribute to China's food-security goals, prevent further biodiversity loss, reduce greenhouse gas emissions and lead to economic savings., (Copyright © 2016 Elsevier Ltd. All rights reserved.)