Pollution characteristics and health risk assessment of polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons during heating season in Beijing

Polycyclic aromatic hydrocarbons(PAHs)and their nitrated derivatives(NPAHs)attract continuous attention due to their outstanding carcinogenicity and mutagenicity.In order to investigate the diurnal variations,sources,formation mechanism,and health risk assessment of them in heating season,particulate matter(PM)were collected in Beijing urban area from December 26,2017 to January 17,2018.PAHs and NPAHs in PM were quantitatively analyzed via gas chromatography-mass spectrometry(GC-MS).Average daily concentrations of PAHs and NPAHs were(78±54)ng/m^(3)and(783±684)pg/m^(3),respectively.The concentrations of them were significantly higher at nighttime than at daytime,and NPAHs concentrations were 1-2 orders of magnitude lower than PAHs concentrations.In the heating season,the dominant species of PAHs include benzo[b]fluoranthene,fluoranthene,pyrene,and chrysene,while 9-nitroanthracene,2+3-nitrofluoranthene,and 2-nitropyrene were dominant species for NPAHs.NPAHs were found to have a single peak during heating and to be primarily distributed in the 0.4-0.7μm particle size.Primary emissions such as biomass burning,coal combustion,and traffic emissions were the major sources of PAHs.NPAHs were produced by the primary source of vehicle emissions and the secondary reaction triggered by OH radicals,as well as biomass burning during daytime.According to the health risk assessment,the total carcinogenic risk was higher in adults than in children.While upon oral ingestion,the carcinogenic risk in children was higher than that of adults,but the risk of adults was higher than children through skin contact and respiratory inhalation.

Chemical characteristics of haze particles in Xi＇an during Chinese Spring Festival： Impact of fireworks burning

Fireworks burning releases massive fine particles and gaseous pollutants, significantly deteriorating air quality during Chinese Lunar New Year （LNY） period. To investigate the impact of the fireworks burning on the atmospheric aerosol chemistry, 1-hr time resolution of PM2.5 samples in Xi＇an during the winter of 2016 including the LNY were collected and detected for inorganic ions, acidity and liquid water content （LWC） of the fine aerosols. PM2.5 during the LNY was 167 ± 87 μg/m^3, two times higher than the China National Ambient Air Quality Standard （75 μg/m^3）. K^＋ （28 wt.% of the total ion mass） was the most abundant ion in the LNY period, followed by SO^2-4 （25 wt.%） and C1^- （18 wt.%）. In contrast, NO^-3 （34 wt.%） was the most abundant species in the haze periods （hourly PM2.5 〉 75 μg/m^3）, followed by SO^2-4 （29.2 wt.%） and NH^＋4 （16.3 wt.%）, while SC94 （35 wt.%） was the most abundant species in the clean periods （hourly PM2.5 〈 75 μg/m^3）, followed by NO^-3 （23.1 wt.%） and NH^＋4 （11 wt.%）. Being different from the acidic nature in the non-LNY periods, aerosol in the LNY period presented an alkaline nature with a pH value of 7.8 ± 1.3. LWC during the LNY period showed a robust linear correlation with K2SO4 and KC1, suggesting that aerosol hygroscopicity was dominated by inorganic salts derived from fireworks burning. Analysis of correlations between the ratios of NO^-3/SO^2-4 and NH^＋4/SO^2-4 indicated that heterogeneous reaction of HNO3 with NH3 was an important formation pathway of particulate nitrate and ammonium during the LNY period.

Seasonal variation and size distribution of biogenic secondary organic aerosols at urban and continental background sites of China

Size-resolved biogenic secondary organic aerosols （BSOA） derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau （a continental background site） and five cities of China were measured using gas chromatography/mass spectrometry （GC/MS）. Concentrations of the determined BSOA are higher in the cities than in the background and are also higher in summer than in winter. Moreover, strong positive correlations （R^2 = 0.44-0.90） between BSOA and sulfate were found at the six sites, suggesting that anthropogenic pollution （i.e., sulfate） could enhance SOA formation, because sulfate provides a surface favorable for acid-catalyzed formation of BSOA. Size distribution measurements showed that most of the determined SOA tracers are enriched in the fine mode （〈3.3 μm） except for cis-pinic and cis-pinonic acids, both presented a comparable mass in the fine and coarse （〉3.3 μm） modes, respectively. Mass ratio of oxidation products derived from isoprene to those from monoterpene in the five urban regions during summer are much less than those in Qinghai Lake region. In addition, in the five urban regions relative abundances of monoterpene oxidation products to SOA are much higher than those of isoprene. Such phenomena suggest that BSOA derived from monoterpenes are more abundant than those from isoprene in Chinese urban areas.

Exploration of a Sequential Gp140-Gp145 Immunization Regimen with Heterologous Envs to Induce a Protective Cross-Reactive HIV Neutralizing Antibody Response In Non-human Primates

Raising a heterologous tier 2 neutralizing antibody(nAb)response remains a daunting task for HIV vaccine development.In this study,we explored the utility of diverse HIV-1 envelope(Env)immunogens in a sequential immunization scheme as a solution to this task.This exploration stemmed from the rationale that gp145,a membrane-bound truncation form of HIV Env,may facilitate the focusing of induced antibody response on neutralizing epitopes when sequentially combined with the soluble gp140 form as immunogens in a prime-boost mode.We first showed that gp140 DNA prime-gp145 Tiantan vaccinia(TV)boost likely represents a general format for inducing potent nAb response in mice.However,when examined in rhesus macaque,this modality showed little effectiveness.To improve the efficacy,we extended the original modality by adding a strong protein boost,namely native-like SOSIP.664 trimer displayed on ferritin-based nanoparticle(NP),which was generated by a newly developed click approach.The resulting three-immunization regimen succeeded in eliciting tier-2 nAb response with substantial breadth when implemented in rhesus macaque over a short 8-week schedule.Importantly,the elicited nAb response was able to effectively contain viremia upon a heterologous SHIV challenge.Collectively,our studies highlighted that diversification of Env immunogens,in both types and formulations,under the framework of a sequential immunization scheme might open new opportunity toward HIV vaccine development.