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1.
Sci Total Environ ; 703: 134475, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31759721

RESUMO

Organic molecular composition of fine aerosols in the free troposphere is poorly understood. Here, PM2.5 (particles with aerodynamic diameters ≤ 2.5 µm) samples were collected at the summit of Mt. Emei (3080 m a.s.l.) in the Southwestern China on a daytime and nighttime basis during summer 2016 (June-July). The samples were analyzed by solvent-extraction followed by derivatization and gas chromatography/mass spectrometry (GC/MS). Four classes of organic compounds, i.e. n-alkanes, fatty acids, saccharides and lignin/resin acids were measured quantitatively. Fatty acids were found to be the most abundant species with an average concentration of 401 ±â€¯419 ng m-3 (range 25.7-1490 ng m-3) in the daytime, similar to the average concentration at night (399 ±â€¯447 ng m-3, 19.6-1970 ng m-3). However, the concentrations of biomass burning tracers (e.g., levoglucosan), primary biological aerosol tracers (e.g., mannitol and arabitol) and low molecular weight n-alkanes derived from fossil fuel combustion in daytime samples were obviously higher than those in nighttime samples. The results suggest that valley breezes transported a large number of aerosols and their precursors from the ground surface to the summit of Mt. Emei in the daytime. Estimated with tracer-based methods, the contributions of biogenic primary sources (plant debris, fungal spore, and biomass burning) to organic carbon was in the range of 3.28-83.5% (22.0 ±â€¯17.5%) in the daytime and 3.45-37.4% (10.9 ±â€¯8.97%) at night. As the largest contributor, biomass burning was an important anthropogenic/natural source of aerosol particles in the free troposphere over Mt. Emei. CAPSULE: Valley/mountain breeze is an important constraint to the temporal variations in organic aerosols over Mt. Emei.

2.
Artigo em Inglês | MEDLINE | ID: mdl-30017911

RESUMO

Glycogen, as an intracellular deposit of polysaccharide, takes important roles in energy balance of many animals. In fish, however, the role of glycogen during development is poorly understood. In the present study, we assessed changes in glycogen concentration and gene expression patterns of glycogen-metabolizing enzymes in developing masu salmon (Oncorhynchus masou masou), a salmonid species inhabiting west side of North Pacific Ocean. As we measured glycogen levels in the bodies and yolk sacs containing the liver separately, the glycogen concentration increased in both parts as the fish developed, whereas it transiently decreased in the yolk sac after hatching, implying glycogen synthesis and breakdown in these tissues. Immunofluorescence staining using anti-glycogen monoclonal antibody revealed localization of glycogen in the liver, muscle and yolk syncytial layer of the pre-hatching embryos and hatched larvae. In order to estimate glycogen metabolism in the fish, the genes encoding homologs of glycogen synthase (gys1 and gys2) and glycogen phosphorylase (pygma, pygmb and pygl) were cloned, and their expression patterns were assessed by quantitative PCR and in situ hybridization. In the fish, gys1 and gys2 were robustly expressed in the muscle and liver, respectively. Also, expression of pyg isoforms was found in muscle, liver and yolk syncytial layer during hatching. With changes in glycogen concentration and expression patterns of relevant genes, our results suggest, for the first time, possible involvement of glycogen in energy balance of fish embryos, especially during hatching.


Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Glicogênio/metabolismo , Fígado/enzimologia , Músculos/enzimologia , Salmão/metabolismo , Animais , Clonagem Molecular , Feminino , Imunofluorescência , Glicogênio Fosforilase/metabolismo , Fígado/crescimento & desenvolvimento , Masculino , Desenvolvimento Muscular , Filogenia , RNA Mensageiro/genética , Salmão/genética , Salmão/crescimento & desenvolvimento
3.
Environ Pollut ; 182: 324-34, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23973884

RESUMO

We analyzed the source-receptor relationships for particulate polycyclic aromatic hydrocarbon (PAH) concentrations in northeastern Asia using an aerosol chemical transport model. The model successfully simulated the observed concentrations. In Beijing (China) benzo[a]pyren (BaP) concentrations are due to emissions from its own domain. In Noto, Oki and Tsushima (Japan), transboundary transport from northern China (>40 °N, 40-60%) and central China (30-40 °N, 10-40%) largely influences BaP concentrations from winter to spring, whereas the relative contribution from central China is dominant (90%) in Hedo. In the summer, the contribution from Japanese domestic sources increases (40-80%) at the 4 sites. Contributions from Japan and Russia are additional source of BaP over the northwestern Pacific Ocean in summer. The contribution rates for the concentrations from each domain are different among PAH species depending on their particulate phase oxidation rates. Reaction with O3 on particulate surfaces may be an important component of the PAH oxidation processes.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluição do Ar/estatística & dados numéricos , Ásia , Modelos Químicos , Material Particulado/análise
4.
Environ Sci Technol ; 46(9): 4941-9, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22435795

RESUMO

The emission, concentration levels, and transboundary transport of particulate polycyclic aromatic hydrocarbons (PAHs) in Northeast Asia were investigated using particulate PAH measurements, the newly developed emission inventory (Regional Emission inventory in ASia for Persistent Organic Pollutants version, REAS-POP), and the chemical transport model (Regional Air Quality Model ver2 for POPs version, RAQM2-POP). The simulated concentrations of the nine particulate PAHs agreed well with the measured concentrations, and the results firmly established the efficacy of REAS/RAQM2-POP. It was found that the PAH concentrations in Beijing (China, source region), which were emitted predominantly from domestic coal, domestic biofuel, and other transformations of coal (including coke production), were approximately 2 orders of magnitude greater than those monitored at Noto (Japan, leeward region). In Noto, the PAH concentrations showed seasonal variations; the PAH concentrations were high from winter to spring due to contributions from domestic coal, domestic biofuel, and other transformations of coal, and low in summer. In summer, these contribution were decrease, instead, other sources, such as the on-road mobile source, were relatively increased compared with those in winter. These seasonal variations were due to seasonal variations in emissions from China, as well as transboundary transport across the Asian continent associated with meteorological conditions.


Assuntos
Poluição do Ar/análise , Atmosfera/análise , Material Particulado/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Simulação por Computador , Extremo Oriente , Modelos Teóricos , Estações do Ano , Incerteza
5.
J Phys Chem A ; 112(11): 2370-7, 2008 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-18288821

RESUMO

The HO2 uptake coefficient (gamma) for inorganic submicrometer wet and dry aerosol particles ((NH4)2SO4 and NaCl) under ambient conditions (760 Torr and 296 +/- 2 K) was measured using an aerosol flow tube (AFT) coupled with a chemical conversion/laser-induced fluorescence (CC/LIF) technique. The CC/LIF technique enabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere. HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position-dependent profiles of LIF intensity were measured as a function of aerosol concentration. Measured gamma values for dry aerosols of (NH4)2SO4 were 0.04 +/- 0.02 and 0.05 +/- 0.02 at 20% and 45% relative humidity (RH), respectively, while those of NaCl were <0.01 and 0.02 +/- 0.01 at 20% and 53% RH, respectively. For wet (NH4)2SO4 aerosols, measured gamma values were 0.11 +/- 0.03, 0.15 +/- 0.03, 0.17 +/- 0.04, and 0.19 +/- 0.04, at 45%, 55%, 65%, and 75% RH, respectively, whereas for wet NaCl aerosols the values were 0.11 +/- 0.03, 0.09 +/- 0.02, and 0.10 +/- 0.02 for 53%, 63%, and 75% RH, respectively. Wet (NH4)2SO4 and NaCl aerosols doped with CuSO4 showed gamma values of 0.53 +/- 0.12 and 0.65 +/- 0.17, respectively. These results suggest that compositions, RH, and phase for aerosol particles are significant to HO2 uptake. Potential HO2 loss processes and their atmospheric contributions are discussed.


Assuntos
Sulfato de Amônio/química , Espécies Reativas de Oxigênio/química , Cloreto de Sódio/química , Aerossóis/química , Atmosfera/química , Radicais Livres/química , Cinética
6.
Sci Total Environ ; 376(1-3): 185-97, 2007 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-17306859

RESUMO

The presence of iodine chemistry, hypothesized due to the overprediction of HO(2) levels by a photochemical box model at Rishiri Island in June 2000, was quantitatively tested against the observed NO/NO(2) ratios and the net production rates of ozone. The observed NO/NO(2) ratios were reproduced reasonably well by considering the conversion of NO to NO(2) by IO, whose amount was calculated so as to reproduce the observed HO(2) levels. However, the net production rates of ozone were calculated to be negative when such high mixing ratios of IO were considered, which was inconsistent with the observed buildup of ozone during daytime. These results suggest that iodine chemistry may not be the sole mechanism for the reduced mixing ratios of HO(2), or that "hot spots" for iodine chemistry were present. Diurnal variations in the mixing ratios of HCHO, CH(3)CHO, peroxy acetyl nitrate (PAN) and HNO(3) observed during the study are presented along with the simulated ones. The box model simulations suggest that the effect of iodine chemistry on these concentrations is small and that important sources of CH(3)CHO and sinks of PAN are probably missing from our current understanding of the tropospheric chemistry mechanism.


Assuntos
Poluentes Atmosféricos/análise , Iodo/química , Modelos Químicos , Poluentes Atmosféricos/química , Aldeídos/análise , Aldeídos/química , Monitoramento Ambiental , Geografia , Peróxido de Hidrogênio/análise , Peróxido de Hidrogênio/química , Japão , Ácido Nítrico/análise , Ácido Nítrico/química , Óxidos de Nitrogênio/análise , Óxidos de Nitrogênio/química , Oxidantes/análise , Oxidantes/química , Oxidantes Fotoquímicos/análise , Oxidantes Fotoquímicos/química , Ozônio/análise , Ozônio/química , Ácido Peracético/análogos & derivados , Ácido Peracético/análise , Ácido Peracético/química , Peróxidos/análise , Peróxidos/química , Fatores de Tempo
7.
Appl Opt ; 45(6): 1254-9, 2006 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-16523790

RESUMO

By employing a commercially available high-voltage switch in a time-gating circuit to drive a channel photomultiplier (CPM), the afterpulse rates are significantly reduced in the time window to collect fluorescence >200 ns after the pulsed laser excitation. The CPM, kept deactivated under normal conditions (normally off), is turned on immediately after the passage of the laser pulse by shifting the voltage applied to the photocathode by 150 V to collect the fluorescence. When the detection system is used as part of a laser-induced fluorescence instrument to measure atmospheric OH radicals with the photon-counting method, the background signal is reduced by more than a factor of 10 as compared with our previous case where a conventional dynode-gated photomultiplier tube (PMT) is used, while the sensitivity toward the fluorescence is almost unchanged. A detection limit as low as 2 x 10(5) radicals cm-3 or 0.008 parts per trillion by volume is achieved for OH, with an integration time of 1 min and a signal-to-noise ratio of 2, enabling sensitive detection of the important radical in the atmosphere. This system is a superior choice with higher sensitivity and cost effectiveness as compared with the gated PMITs utilizing a microchannel plate as an electron multiplier, and could also be used effectively in light detection and ranging (lidar) instruments, where a delayed scattering signal would be efficiently discriminated from afterpulses.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/instrumentação , Radical Hidroxila/análise , Aumento da Imagem/instrumentação , Lasers , Fotometria/instrumentação , Espectrometria de Fluorescência/instrumentação , Eletrônica , Monitoramento Ambiental/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Fotometria/métodos , Reprodutibilidade dos Testes , Semicondutores , Sensibilidade e Especificidade , Processamento de Sinais Assistido por Computador/instrumentação , Espectrometria de Fluorescência/métodos
8.
Science ; 302(5651): 1716-9, 2003 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-14657488

RESUMO

The impact of global air pollution on climate and the environment is a new focus in atmospheric science. Intercontinental transport and hemispheric air pollution by ozone jeopardize agricultural and natural ecosystems worldwide and have a strong effect on climate. Aerosols, which are spread globally but have a strong regional imbalance, change global climate through their direct and indirect effects on radiative forcing. In the 1990s, nitrogen oxide emissions from Asia surpassed those from North America and Europe and should continue to exceed them for decades. International initiatives to mitigate global air pollution require participation from both developed and developing countries.

9.
Chem Rec ; 2(3): 199-211, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12112871

RESUMO

OH and HO(2) radicals, atmospheric detergents, and the reservoir thereof, play central roles in tropospheric chemistry. In spite of their importance, we had no choice but to trust their concentrations predicted by modeling studies based on known chemical processes. However, recent direct measurements of these radicals have enabled us to test and revise our knowledge of the processes by comparing the predicted and observed values of the radical concentrations. We developed a laser-induced fluorescence (LIF) instrument and successfully observed OH and HO(2) at three remote islands of Japan (Oki Island, Okinawa Island, and Rishiri Island). At Okinawa Island, the observed daytime level of HO(2) agreed closely with the model estimates, suggesting that the photochemistry at Okinawa is well described by the current chemistry mechanism. At Rishiri Island, in contrast, the observed daytime level of HO(2) was consistently much lower than the calculated values. We proposed that iodine chemistry, usually not incorporated into the mechanism, is at least partly responsible for the discrepancy in the results. At night, HO(2) was detected at levels greater than 1 pptv at all three islands, suggesting the presence of processes in the dark that produce radicals. We showed that ozone reactions with unsaturated hydrocarbons, including monoterpenes, could significantly contribute to radical production.


Assuntos
Atmosfera/química , Radical Hidroxila/análise , Radical Hidroxila/química , Iodo/química , Japão , Fotoquímica
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