Observation and analysis of atmospheric volatile organic compounds in a typical petrochemical area in Yangtze River Delta, China.

Volatile organic compounds (VOCs) are a kind of important precursors for ozone photochemical formation. In this study, VOCs were measured from November 5th, 2013 to January 6th, 2014 at the Second Jinshan Industrial Area, Shanghai, China. The results showed that the measured VOCs were dominated by alkanes (41.8%), followed by aromatics (20.1%), alkenes (17.9%), and halo-hydrocarbons (12.5%). The daily trend of the VOC concentration showed a bimodal feature due to the rush-hour traffic in the morning and at nightfall. Based on the VOC concentration, a receptor model of Positive Matrix Factorization (PMF) coupled with the information related to VOC sources was applied to identify the major VOC emissions. The result showed five major VOC sources: solvent use and industrial processes were responsible for about 30% of the ambient VOCs, followed by rubber chemical industrial emissions (23%), refinery and petrochemical industrial emissions (21%), fuel evaporations (13%) and vehicular emissions (13%). The contribution of generalized industrial emissions was about 74% and significantly higher than that made by vehicle exhaust. Using a propylene-equivalent method, alkenes displayed the highest concentration, followed by aromatics and alkanes. Based on a maximum incremental reactivity (MIR) method, the average hourly ozone formation potential (OFP) of VOCs is 220.49 ppbv. The most significant source for ozone chemical formation was identified to be rubber chemical industrial emissions, following one by vehicular emission. The data shown herein may provide useful information to develop effective VOC pollution control strategies in industrialized area.

An observational study of nitrous acid (HONO) in Shanghai, China: The aerosol impact on HONO formation during the haze episodes.

Continuous HONO measurement was conducted to study the formation features of HONO during the haze episodes at Shanghai, China. The HONO concentration ranged from 0.26 to 5.84ppb and averaged at 2.31ppb during the measurement period. The HONO concentration during the haze episode (P1), the haze-fog episode (P2) and the clean period (P3) were 2.80, 2.35 and 1.78ppb, respectively. Heterogeneous conversion of NO2 was the dominate pathway for nocturnal HONO formation, and the heterogeneous conversion efficiency of NO2 to HONO was closely associated with the PM2.5 concentration. The averaged heterogeneous conversion rate of NO2-to-HONO (CHONO) during the pollution periods (P1+P2) was 1.58×10-2h-1, higher than that during the clean period (P3) (0.93×10-2h-1), suggesting the higher conversion potential of NO2 to HONO during the pollution episodes. The daytime unknown HONO production rate (Punknown) in the pollution period was 2.98ppb/h, higher than 1.78ppb/h in the clean period. Further, aerosol played a role in Punknown during the transformation of the clean period to the pollution period. At a single particle scale, transmission electron microscopy (TEM) images revealed that most of the particles during P1 and P2 were agglomerated, whereas the particles collected from P3 were uniformly distributed and showed simple morphologies. The number percentage of the S/N-bearing particles during P1 (34%) and P2 (27%) were higher than that during P3 (20%). In addition, particles contained more internally mixed nitrates during P1 and P2 than those during P3, suggesting more intense heterogeneous conversion of NO2 to HONO on particle surfaces during the pollution episodes. In the present study, the averaged HONO/NOx ratio (5.60%), especially during P1 (7.80%) and P2 (7.50%) was much higher than that assumed global averaged value of 2.0%, suggesting a potentially important role for the HONO chemistry in Shanghai. This study provides new insights into the HONO formation mechanism in the atmosphere characterized by high fine particle level.

Edible ginger-derived nanoparticles: A novel therapeutic approach for the prevention and treatment of inflammatory bowel disease and colitis-associated cancer.

There is a clinical need for new, more effective treatments for chronic and debilitating inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis. In this study, we characterized a specific population of nanoparticles derived from edible ginger (GDNPs 2) and demonstrated their efficient colon targeting following oral administration. GDNPs 2 had an average size of ∼230 nm and exhibited a negative zeta potential. These nanoparticles contained high levels of lipids, a few proteins, ∼125 microRNAs (miRNAs), and large amounts of ginger bioactive constituents (6-gingerol and 6-shogaol). We also demonstrated that GDNPs 2 were mainly taken up by intestinal epithelial cells (IECs) and macrophages, and were nontoxic. Using different mouse colitis models, we showed that GDNPs 2 reduced acute colitis, enhanced intestinal repair, and prevented chronic colitis and colitis-associated cancer (CAC). 2D-DIGE/MS analyses further identified molecular target candidates of GDNPs 2 involved in these mouse models. Oral administration of GDNPs 2 increased the survival and proliferation of IECs and reduced the pro-inflammatory cytokines (TNF-α, IL-6 and IL-1ß), and increased the anti-inflammatory cytokines (IL-10 and IL-22) in colitis models, suggesting that GDNPs 2 has the potential to attenuate damaging factors while promoting the healing effect. In conclusion, GDNPs 2, nanoparticles derived from edible ginger, represent a novel, natural delivery mechanism for improving IBD prevention and treatment with an added benefit of overcoming limitations such as potential toxicity and limited production scale that are common with synthetic nanoparticles.

Individual particle analysis of aerosols collected at Lhasa City in the Tibetan Plateau.

To understand the composition and major sources of aerosol particles in Lhasa City on the Tibetan Plateau (TP), individual particles were collected from 2 February to 8 March, 2013 in Tibet University. The mean concentrations of both PM2.5 and PM10 during the sampling were 25.7±21.7 and 57.2±46.7 µg/m3, respectively, much lower than those of other cities in East and South Asia, but higher than those in the remote region in TP like Nam Co, indicating minor urban pollution. Combining the observations with the meteorological parameters and back trajectory analysis, it was concluded that local sources controlled the pollution during the sampling. Transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectra (EDS) was used to study 408 particles sampled on four days. Based on the EDS analysis, a total of 8 different particle categories were classified for all 408 particles, including Si-rich, Ca-rich, soot, K-rich, Fe-rich, Pb-rich, Al-rich and other particles. The dominant elements were Si, Al and Ca, which were mainly attributed to mineral dust in the earth's crust such as feldspar and clay. Fe-, Pb-, K-, Al-rich particles and soot mainly originated from anthropogenic sources like firework combustion and biomass burning during the sampling. During the sampling, the pollution mainly came from mineral dust, while the celebration ceremony and religious ritual produced a large quantity of anthropogenic metal-bearing particles on 9 and 25 February 2013. Cement particles also had a minor influence. The data obtained in this study can be useful for developing pollution control strategies.

Investigation into adsorption and photocatalytic degradation of gaseous benzene in an annular fluidized bed photocatalytic reactor.

The adsorption and photocatalytic degradation of gaseous benzene were investigated considering the operating variables and kinetic mechanism using nano-titania agglomerates in an annular fluidized bed photocatalytic reactor (AFBPR) designed. The special adsorption equilibrium constant, adsorption active sites, and apparent reaction rate coefficient of benzene were determined by linear regression analysis at various gas velocities and relative humidities (RH). Based on a series of photocatalytic degradation kinetic equations, the influences of operating variables on degradation efficiency, apparent reaction rate coefficient and half-life were explored. The findings indicated that the operating variables have obviously influenced the adsorption/photocatalytic degradation and corresponding kinetic parameters. In the photocatalytic degradation process, the relationship between photocatalytic degradation efficiency and RH indicated that water molecules have a dual-function which was related to the structure characteristics of benzene. The optimal operating conditions for photocatalytic degradation of gaseous benzene in AFBPR were determined as the fluidization number at 1.9 and RH required related to benzene concentration. This investigation highlights the importance of controlling RH and benzene concentration in order to obtain the desired synergy effect in photocatalytic degradation processes.