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1.
Gene ; 808: 145991, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34626723

RESUMO

Porcine circovirus 4 (PCV4) was identified as a novel porcine circovirus in China in 2019. To investigate the prevalence and genetic characteristics of PCV2 and PCV4, 133 clinical samples (103 tissue samples and 30 serum samples) were collected from 30 different pig farms in Henan province of China, and a SYBR Green I-based duplex quantitative real-time polymerase chain reaction assay was established to detect PCV2 and PCV4 genomes simultaneously. The complete genome sequences of 20 PCV2 and 6 PCV4 strains from 19 and 6 clinical samples respectively were sequenced and analyzed. The results showed the detection limits of this assay were 80.2 copies/µL for PCV2 and 58.6 copies/µL for PCV4. The detection results of clinical samples revealed the PCV2 positive rate was 63.16% (84/133), the PCV4 positive rate was 33.33% (45/133), and the PCV2 and PCV4 co-infection positive rate was 21.05% (28/133). Among 20 PCV2 strains, 6 belonged to PCV2a, 6 belonged to PCV2b and 8 belonged to PCV2d. Co-infection with JZ1 (PCV2b) and JZ2 (PCV2d) strains was identified in one sample (JZ-1). Eleven putative recombination events were found through the recombination analysis, suggesting that the new PCV2 variant strains had circulated in Henan province, which contributes to our understanding of evolutionary characteristics of PCV2 in China. The possible genotypes of PCV4 strains were determined based on genomic sequences of 6 PCV4 strains in this study and 29 PCV4 reference strains available at GenBank. According to three different phylogenetic trees (ORF1, ORF2 and complete genome), all 35 PCV4 strains were clustered into two major genotypes (PCV4a and PCV4b), and 6 PCV4 strains in this study belonged to PCV4a. Additionally, the functional regions of PCV4 strains were predicted by comparison with other circoviruses, which are conducive to the further study of the biological functions of PCV4 genome.

2.
Environ Sci Technol ; 55(17): 11557-11567, 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34431667

RESUMO

The lockdown due to COVID-19 created a rare opportunity to examine the nonlinear responses of secondary aerosols, which are formed through atmospheric oxidation of gaseous precursors, to intensive precursor emission reductions. Based on unique observational data sets from six supersites in eastern China during 2019-2021, we found that the lockdown caused considerable decreases (32-61%) in different secondary aerosol components in the study region because of similar-degree precursor reductions. However, due to insufficient combustion-related volatile organic compound (VOC) reduction, odd oxygen (Ox = O3 + NO2) concentration, an indicator of the extent of photochemical processing, showed little change and did not promote more decreases in secondary aerosols. We also found that the Chinese provinces and international cities that experienced reduced Ox during the lockdown usually gained a greater simultaneous PM2.5 decrease than other provinces and cities with an increased Ox. Therefore, we argue that strict VOC control in winter, which has been largely ignored so far, is critical in future policies to mitigate winter haze more efficiently by reducing Ox simultaneously.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , COVID-19 , Aerossóis/análise , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Poluição do Ar/prevenção & controle , China , Controle de Doenças Transmissíveis , Monitoramento Ambiental , Humanos , Oxigênio , Material Particulado/análise , SARS-CoV-2
3.
Chaos ; 31(6): 063127, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34241305

RESUMO

Digital memcomputing machines (DMMs) are a novel, non-Turing class of machines designed to solve combinatorial optimization problems. They can be physically realized with continuous-time, non-quantum dynamical systems with memory (time non-locality), whose ordinary differential equations (ODEs) can be numerically integrated on modern computers. Solutions of many hard problems have been reported by numerically integrating the ODEs of DMMs, showing substantial advantages over state-of-the-art solvers. To investigate the reasons behind the robustness and effectiveness of this method, we employ three explicit integration schemes (forward Euler, trapezoid, and Runge-Kutta fourth order) with a constant time step to solve 3-SAT instances with planted solutions. We show that (i) even if most of the trajectories in the phase space are destroyed by numerical noise, the solution can still be achieved; (ii) the forward Euler method, although having the largest numerical error, solves the instances in the least amount of function evaluations; and (iii) when increasing the integration time step, the system undergoes a "solvable-unsolvable transition" at a critical threshold, which needs to decay at most as a power law with the problem size, to control the numerical errors. To explain these results, we model the dynamical behavior of DMMs as directed percolation of the state trajectory in the phase space in the presence of noise. This viewpoint clarifies the reasons behind their numerical robustness and provides an analytical understanding of the solvable-unsolvable transition. These results land further support to the usefulness of DMMs in the solution of hard combinatorial optimization problems.

4.
Infect Genet Evol ; 94: 105016, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34325052

RESUMO

Porcine circovirus type 2 (PCV2) is the causative agent of porcine circovirus-associated diseases (PCVAD), causing substantial economic losses to the swine industry worldwide. PCV3, as a recently discovered virus, is associated with porcine dermatitis, nephropathy syndrome, reproductive failure, congenital tremors, and other clinical symptoms. To further investigate the epidemic profile and genetic diversity of the two viruses, a total of 198 samples from swine at various growth stages suspected for PCVAD on 55 different pig farms between 2018 and 2020 were analyzed for presence of PCV2 and PCV3 by using a multiplex real-time PCR assay. Among the 198 samples, 113 (57.07%) and 72 (36.36%) were positive for PCV2 and PCV3 respectively, and 39 (19.7%) were positive for PCV2 and PCV3 co-infection. Subsequently, whole genome sequences of 34 PCV2 and 19 PCV3 strains were obtained from 30 and 19 clinical samples, respectively. Of these, 8 PCV2 strains belonged to PCV2a, 10 belonged to PCV2b and 16 belonged to PCV2d, indicating PCV2d was the predominant PCV2 genotype circulating in central China. Furthermore, co-infection of different PCV2 genotype strains was identified in three samples (JZ-4, KF-2 and JY-1), and a cross-recombination was found in the ORF2 region of the sequenced 13 PCV2d strains whose putative parental strains were LN6/1999 (MF278777) and MEX/41238/2014 (KT795287) strains. The phylogenetic analysis of PCV3 showed high nucleotide identity (>98%) among sequences obtained in this study and reference sequences. These data will aid our understanding of the molecular epidemiology and evolution of PCV2 and PCV3.

5.
Transbound Emerg Dis ; 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34076964

RESUMO

Porcine circovirus 4 (PCV4), a novel circovirus, was first discovered in April 2019 in Hunan Province of China. At present, PCV4 infection has been detected in China and South Korea. However, until 2019, there was little information about its circulating status and genetic characteristics. To further clarify the origin and prevalence of PCV4, a total of 152 clinical samples collected from 49 different swine farms of 15 cities in Henan Province of China from 2011 to 2021 were tested for the presence of PCV4 by qPCR, and the complete genome of PCV4 strains was amplified from the positive samples and sequenced. Among these samples, 45.39% (69/152) were positive for PCV4 and 86.67% (13/15) of the cities and 67.35% (33/49) of the swine farms were positive for PCV4. The genome sequences of 15 PCV4 strains were obtained, of which two PCV4 strains (HN-ZMD-201212 and HN-XX-201212) were achieved from archival samples in 2012, indicating that PCV4 has been circulating for at least 10 years in Henan Province of China. The phylogenetic analysis showed that 15 PCV4 strains in our study together with PCV4 strain HNU-AHG1-2019 were clustered into an identical but separate evolutionary branch, with genomic identity ranging from 98.2% to 98.8%. Our research further provides significant epidemiological information on PCV4 in China, which will help understand the origin and genetic characteristics of this new virus.

6.
J Virol Methods ; 293: 114152, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33845107

RESUMO

Porcine circovirus 4 (PCV4) was a novel circovirus identified from diseased pigs in 2019 in Hunan Province, China, and PCV3 and PCV4 co-infection has been reported. In order to detect and differentiate PCV3 and PCV4 simultaneously, the SYBR Green І-based duplex quantitative PCR (qPCR) assay was established in the present study. The two viruses could be easily distinguished by different Tm values: 86.5°C for PCV3 and 79°C for PCV4, while other porcine pathogens did not shown specific melting peaks. The detection limits of this duplex qPCR assay were 51.7 copies/µL for PCV3 and 67.7 copies/µL for PCV4, and both of the intra-assay and inter-assay of the CV analysis of this assay were less than 2.0 %. Sixty-four clinical samples from 22 different swine farms were screened by the duplex qPCR assay. The results showed that the positive detection rate of PCV3 was 37.5 % (24/64) and PCV4 was 34.38 % (22/64), and PCV3 and PCV4 co-infection rate was 17.19 % (11/64). The detection rate of the duplex qPCR assay was higher than that of the conventional PCR assay. The duplex qPCR was of high sensitivity and specificity, being able to provide technical support for clinical detection, differential diagnosis and control of PCV3 and PCV4.


Assuntos
Infecções por Circoviridae , Circovirus , Doenças dos Suínos , Animais , China , Infecções por Circoviridae/diagnóstico , Infecções por Circoviridae/veterinária , Circovirus/genética , Filogenia , Reação em Cadeia da Polimerase em Tempo Real , Reprodutibilidade dos Testes , Suínos , Doenças dos Suínos/diagnóstico
7.
Phys Rev Lett ; 125(17): 170501, 2020 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-33156669

RESUMO

Quantum compiling, a process that decomposes the quantum algorithm into a series of hardware-compatible commands or elementary gates, is of fundamental importance for quantum computing. We introduce an efficient algorithm based on deep reinforcement learning that compiles an arbitrary single-qubit gate into a sequence of elementary gates from a finite universal set. It generates near-optimal gate sequences with given accuracy and is generally applicable to various scenarios, independent of the hardware-feasible universal set and free from using ancillary qubits. For concreteness, we apply this algorithm to the case of topological compiling of Fibonacci anyons and obtain near-optimal braiding sequences for arbitrary single-qubit unitaries. Our algorithm may carry over to other challenging quantum discrete problems, thus opening up a new avenue for intriguing applications of deep learning in quantum physics.

8.
Huan Jing Ke Xue ; 35(11): 4070-7, 2014 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-25639078

RESUMO

Based on preliminary studies by aerosol time-of-flight mass spectrometer (ATOFMS) and single particle aerosol mass spectrometer (SPAMS), typical methods for identifying the number of particles (or particle count) for five major components including sulfate, nitrate, ammonium, organic carbon (OC), and elemental carbon (EC) in China and abroad were summarized. In this study, combined with the characteristics of single particle mass spectrum by SPAMS, an optimized method is proposed. With field measurement using SPAMS during January 2013 in Beijing, particle counts of sulfate, nitrate, ammonium, OC, and EC determined by different methods were compared. The comparison with results of off-line filter analyses for these five components proved that the method proposed in this study is comparable and optimized. We also suggest factors needed to be considered in future application of SPAMS and other areas that require in-depth research.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/instrumentação , Espectrometria de Massas/métodos , Material Particulado/análise , Aerossóis/análise , Compostos de Amônio/análise , Carbono/análise , China , Nitratos/análise , Sulfatos/análise
9.
Huan Jing Ke Xue ; 35(11): 4404-14, 2014 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-25639123

RESUMO

Organic aerosol is one of the most important components of atmospheric aerosols. In recent years, organic aerosol has been found and proved to be light absorbing in UV-Visible region. Light absorbing organic carbon (also named as brown carbon) has been one of the forefronts in the field of atmospheric research. Its light absorption contributions to radiative forcing, regional air quality, and global climate change have drawn much attention. Regional air pollution is complex in China. Frequent visibility decline and severe regional haze episodes occurred since January 2013. Previous studies showed high amount of estimated columnar light-absorbing organic carbon in China, and according to current research findings, major sources of fine particulate matter in China (e. g. biomass burning and fossil fuel combustion) were also recognized as the main sources for brown carbon. Considering the high abundance of brown carbon in atmosphere, there is a great need to reconsider and reevaluate contributions of organic aerosol to light absorption, especially its role in haze formation and radiative forcing. However, up to now, basic researches on light absorbing organic carbon are still limited in China. This study aimed to elucidate the need for basic research on brown carbon, summarize previous studies and research progress from different aspects such as sources, composition, measurement, mass concentration distribution, optical property, radiative forcing of brown carbon, point out the existing problems and deficiencies, and put forward suggestions for future study.


Assuntos
Poluição do Ar/análise , Carbono/análise , Aerossóis/análise , Atmosfera , China , Mudança Climática , Luz , Material Particulado/análise
10.
Huan Jing Ke Xue ; 32(4): 930-5, 2011 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-21717728

RESUMO

The atmospheric nucleation rates are calculated, the nucleation mechanism and factors affecting the calculation are investigated at Xinken Site in the Pearl River Delta of China. Based on particle size distribution data from Xinken site during PRIDE-PRD2004, the apparent formation rates of 3 nm particles are obtained. Nucleation rates for critical nuclei of 1 nm size are analyzed from particle flux equation of different size in the diameter axis. The results show the 3 nm apparent formation rates during the new particle formation events are 7.2-9.4 cm(-3) x s(-1), the atmospheric nucleation rate for 1 nm critical nuclei are 7.65 x 10(2)-1.14 x 10(5) cm(-3). The derived nucleation rates are consistent with the concentrations of precursor vapor sulphuric acid, which are supposed to participate nucleation in most cases. With higher contribution of accumulation mode background aerosol to coagulation sink, the variation in particle number during event period imposes neglectable influence on the calculated nucleation rates. Information on nucleation rates provide further insight into the nucleation mechanism. Since variation in critical nuclei size may lead large uncertainty to nucleation rates, identification of the exact critical nuclei size is important for nucleation rate study.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Material Particulado/análise , Aerossóis/análise , Atmosfera/análise , China , Tamanho da Partícula , Rios
11.
Huan Jing Ke Xue ; 30(3): 631-6, 2009 Mar 15.
Artigo em Chinês | MEDLINE | ID: mdl-19432304

RESUMO

Characterizations and their primary sources of 17 carbonyls compounds in the serious air polluted summer-days of 2006 were studied by DNPH-HPLC-UV measurement methods. Results were shown as follows, acetone was found to be the most predominant carbonyls followed by formaldehyde, 2-butone and acetaldehyde, with the 24 h average concentrations of 10.84, 9.29, 8.35, 8.0 microg x m(-3) respectively, which accounted for 72.29% of total carbonyl compounds in the atmosphere. Among the four sites, the highest level of total carbonyl compounds was 59.66 microg x m(-3) at the urban site of Guangdong Provincial Centre of Environmental Monitor, the lowest was 43.51 microg x m(-3) at the rural site of Conghua. Different variation characterizations of each carbonyl compounds at there different height sites were found, and the diurnal variation was shown that the total concentration of carbonyl compounds in daytime was much higher than that of nighttime. Good correlations between formaldehyde, acetaldehyde and acetone indicated that they mainly derived from the same sources, and the value that C1/C2 and C2/C3 ratios were 1.12 and 7.51 respectively implied that the important pollution sources of carbonyl compounds was vehicular exhaust in Guangzhou.


Assuntos
Acetaldeído/análise , Acetona/análise , Poluentes Atmosféricos/análise , Formaldeído/análise , Emissões de Veículos/análise , China , Compostos Orgânicos Voláteis/análise
12.
Environ Sci Technol ; 42(12): 4461-6, 2008 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-18605571

RESUMO

Little is known about the characteristics of particulate matter emissions from vehicles in China, although such information is critical in source apportionment modeling, emission inventories, and health effect studies. In this paper, we report a comprehensive characterization of PM2.5 emissions in the Zhujiang Tunnel in the Pearl River Delta region of China. The chemical speciation included elemental carbon, organic carbon, inorganic ions, trace elements, and organic compounds. The emission factors of individual species and their relative distributions were obtained for a mixed fleet of heavy-duty vehicles (19.8%) and light-duty vehicles (80.2%). In addition, separate emission factors of PM2.5 mass, elemental carbon, and organic matter for heavy-duty vehicles and light-duty vehicles also were derived. As compared to the results of other tunnel studies previously conducted, we found that the abundances and distributions of the trace elements in PM2.5 emissions were more varied. In contrast, the characteristics of the trace organic compounds in the PM2.5 emissions in our study were consistent with characteristics found in other tunnel studies and dynamometer tests. Our results suggested that vehicular PM2.5 emissions of organic compounds are less influenced by the geographic area and fleet composition and thereby are more suitable for use in aerosol source apportionment modeling implemented across extensive regions.


Assuntos
Emissões de Veículos , China
13.
J Environ Sci (China) ; 19(2): 167-75, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17915724

RESUMO

Cereal straw is one of the most abundant biomass burned in China but its contribution to fine particulates is not adequately understood. In this study, three main kinds of cereal straws were collected from five grain producing areas in China. Fine particulate matters (PM2.5) from the cereal straws subjected to control burnings, both under smoldering and flaming status, were sampled by using a custom made dilution chamber and sampling system in the laboratory. Element carbon (EC) and organic carbon (OC) was analyzed. 141 compounds of organic matters were measured by gas chromatography-mass spectrum (GC-MS). Source profiles of particulate organic matters emitted from cereal straw burnings were obtained. The results indicated that organic matters contribute a large fraction in fine particulate matters. Levoglucosan had the highest contributions with averagely 4.5% in mass of fine particulates and can be considered as the tracer of biomass burnings. Methyloxylated phenols from lignin degradation also had high concentrations in PM2.5, and contained approximately equal amounts of guaiacyl and syringyl compounds. beta-Sitostrol also made up relatively a large fraction of PM2.5 compared with the other sterols (0.18%-0.63% of the total fine particle mass). Normal alkanes, PAHs, fatty acids, as well as normal alkanols had relatively lower concentrations compared with the compounds mentioned above. Carbon preference index (CPI) of normal alkanes and alkanoic acids showed characteristics of biogenic fuel burnings. Burning status significantly influenced the formations of EC and PAHs. The differences between the emission profiles of straw and wood combustions were displayed by the fingerprint compounds, which may be used to identify the contributions between wood and straw burnings in source apportionment researches.


Assuntos
Poluentes Atmosféricos/análise , Grão Comestível , Fumaça/análise , Agricultura/métodos , Carboidratos/análise , Ácidos Graxos/análise , Temperatura Alta , Compostos Orgânicos/análise , Tamanho da Partícula , Esteróis/análise , Gerenciamento de Resíduos/métodos
14.
Huan Jing Ke Xue ; 28(7): 1614-20, 2007 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-17891978

RESUMO

The concentration of methyl tert-butyl ether (MTBE) and its spatio-temporal distribution were researched in atmosphere of the Pearl River Delta (PRD) by sampling with air sampling canisters and analyzing with pre-concentrator and gas chromatograph-mass spectrum instrument. The results showed that 1) MTBE could be prevalently checked in atmosphere of traffic area, industrial area, residential area and commercial area of the PRD, and its range of hourly average concentration in the long-term observation was from 0 - 1.250 microg m(-3), the summer had more serious pollution than the spring, and urban was the central area of high MTBE concentration, and suburban in the downwind was obviously polluted by the urban air. 2) During the enhanced observation in summertime, the diurnal average concentration of Guangzhou urban site was (1.520 +/- 0.370) microg m(-3), which was about 7 times of Huadou site in the downwind of Guangzhou and over 100 times of Conghua site in the background of Guangzhou. In urban, 2 peak values appeared in the period of 10:00 - 12:00 and 16:00 - 18:00 respectively, and the nighttime had the lowest average concentration, but the suburban in the downwind had the peak value in the nighttime. 3) During the enhanced observation in wintertime, the diurnal average concentration of Guangzhou urban site was (0.950 +/- 0.240) microg m(-3), which was 3.6 times of Xinken site in the downwind of Guangzhou. Several peak values appeared on the diurnal variation, the high concentration period of urban was in 18:00 - 22:00, and that of suburban was in 04:00 - 10:00 of the next day. 4) When it was weak sunshine, the concentration of MTBE beside the urban traffic roadside was decreasing with the height increasing, but when it was strong sunshine, it was increasing with the height increasing. So, except the original emission from the automobiles, MTBE still had the secondary pollution sources formed by air photochemical reaction.


Assuntos
Poluentes Atmosféricos/análise , Atmosfera/análise , Éteres Metílicos/análise , China , Cromatografia Gasosa-Espectrometria de Massas , Rios
15.
J Environ Sci (China) ; 18(3): 475-81, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-17294643

RESUMO

The pollution of particulate matter less than 2.5 microm (PM2.5) is a serious environmental problem in Beijing. The annual average concentration of PM2.5 in 2001 from seasonal monitor results was more than 6 times that of the U.S. national ambient air quality standards proposed by U.S. EPA. The major contributors to mass of PM2.5 were organics, crustal elements and sulfate. The chemical composition of PM2.5 varied largely with season, but was similar at different monitor stations in the same season. The fine particles (PM2.5) cause atmospheric visibility deterioration through light extinction. The mass concentrations of PM2.5 were anti-correlated to the visibility, the best fits between atmospheric visibility and the mass concentrations of PM2.5 were somehow different: power in spring, exponential in summer, logarithmic in autumn, power or exponential in winter. As in each season the meteorological parameters such as air temperature and relative humidity change from day to day, probably the reason of above correlations between PM2.5 and visibility obtained at different seasons come from the differences in chemical compositions of PM2.5.


Assuntos
Poluição do Ar/análise , Cidades , Monitoramento Ambiental/estatística & dados numéricos , Estações do Ano , China , Umidade , Tamanho da Partícula , Temperatura
16.
Sci Total Environ ; 359(1-3): 167-76, 2006 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-16083946

RESUMO

Beijing is a rapidly developing city with severe and unique air pollution problems. Organic matter is the most abundant fraction in fine particles in Beijing, occupying 30-50% of the total mass, indicating its key role in air pollution control. However, detailed chemical characterization of particulate organic matter in Beijing has never been reported. In this study, fine particles in the urban atmosphere in Beijing were investigated for its organic components by GC/MS technique. Over 100 individual organic compounds were identified and quantified in 25 PM2.5 samples from the summer, autumn and winter of 2002-2003. Alkanes, fatty acids, dicarboxylic acids, polycyclic aromatic hydrocarbons and some important tracer compounds (hopanes, levoglucosan and steroids) were the major constituents with the sum of their concentrations of 502, 1471 and 1403 ng m(-3) in summer, autumn and winter, respectively. Different organic compounds presented apparently different seasonal characteristics, reflecting their different dominant emission sources, such as coal combustion, biomass burning and cooking emission. The abundance and origin of these organic compounds are discussed to reveal seasonal air pollution characteristics of Beijing.


Assuntos
Poluentes Atmosféricos/análise , Poeira/análise , Compostos Orgânicos/análise , Poluição do Ar , China , Colesterol/análise , Cidades , Monitoramento Ambiental , Cromatografia Gasosa-Espectrometria de Massas , Glucose/análogos & derivados , Glucose/análise , Tamanho da Partícula , Estações do Ano , Sitosteroides/análise
17.
Chemosphere ; 62(10): 1565-73, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16087214

RESUMO

Vehicle populations in China have been increasing sharply since 1990s. Vehicle emissions including various gaseous pollutants and particulate matter cause deterioration of air quality. However, measurements of particulate mater from on-road vehicles in China are scarcely reported, and thus the chemical compositions of particles emitted from vehicles in China are unknown. In this research, tunnel experiments were performed to measure PM2.5 in the Wutong tunnel, Shenzhen, China. Detailed PM2.5 chemical compositions, with organic compounds determined by GC/MS, in the tunnel were presented. Elemental carbon and organic matter composed 63% and 34% of the total PM2.5 mass in the Wutong tunnel, respectively. Alkanes, PAHs, hopanes, fatty acids, and dicarboxylic acids were the major identified organic compounds, and their source profiles in the PM2.5 in the Wutong tunnel were characterized. The comparisons of our measurements with those in the literature were also made to demonstrate the characteristics of the vehicle source profiles in the Wutong tunnel. The experimental results in this paper can improve understanding of particulate matter emitted from vehicles in China.


Assuntos
Poluentes Atmosféricos/química , Monitoramento Ambiental , Emissões de Veículos/análise , China , Tamanho da Partícula
18.
Huan Jing Ke Xue ; 25(5): 15-20, 2004 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-15623015

RESUMO

A determination method was developed for the quantification of polar organic compounds in atmospheric fine particles in Beijing City by GC-MS. The optimally reactive conditions of two derivative methods were set up. The related coefficients (R2) of standard curves were 0.995-1.000. The precise of the GC-MS was 1%-10%, and the quantified detection limits ranged from 0.1 to 4.0 ng x microL(-1) depending on the various standard compounds. The percent relative standard deviation of standards and atmospheric samples were 3%-20% and 3%-17%, respectively. The methods were applied for Beijing fine particle samples in summer, fall, and winter in 2002. Total 42 polar organic compounds were identified and quantified, including 30 n-aliphatic and n-alkenoic acid species, 5 aliphatic dicarboxylic acid species, 3 monosaccharide anhydrides, 3 steroids, and benzoic acid. The sources of these compounds were discussed.


Assuntos
Poluentes Atmosféricos/análise , Compostos Orgânicos/análise , China , Cromatografia Gasosa-Espectrometria de Massas , Tamanho da Partícula
19.
J Environ Sci (China) ; 16(5): 860-4, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15559829

RESUMO

The recent year's monitor results of Beijing indicated that the pollution level of fine particles PM2.5 showed an increasing trend. To understand pollution characteristics of PM2.5 and its relationship with the meteorological conditions in Beijing, a one-year monitoring of PM2.5 mass concentration and correspondent meteorological parameters was performed in Beijing in 2001. The PM2.5 levels in Beijing were very high, the annual average PM2.5 concentration in 2001 was 7 times of the National Ambient Air Quality Standards proposed by US EPA. The major chemical compositions were organics, sulfate, crustals and nitrate. It was found that the mass concentrations of PM2.5 were influenced by meteorological conditions. The correlation between the mass concentrations of PM2.5 and the relative humidity was found. And the correlation became closer at higher relative humidity. And the mass concentrations of PM2.5 were negtive-correlated to wind speeds, but the correlation between the mass concentration of PM2.5 and wind speed was not good at stronger wind.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/estatística & dados numéricos , Estações do Ano , Tempo (Meteorologia) , China , Umidade , Tamanho da Partícula , Espectrometria por Raios X , Fatores de Tempo , Vento
20.
J Environ Sci (China) ; 16(4): 570-5, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15495958

RESUMO

PM2.5 samples were collected by a three-stage cascade impactor at two kinds of Chinese restaurants to characterize fine organic particulate matter from Chinese cooking sources. Major individual organic compounds have been quantified by GC/MS, including series of alkanes, n-alkanoic acids, n-alkanals, alkan-2-ones and PAHs. Alkanes and ketones make up a significant fraction of particle-phase organic compounds, ranging from C11 to C26, and C9 to C19, respectively. In addition, other organic compound classes have been identified, such as alkanols, esters, furans, lactones, amides, and nitriles. The mass concentrations of fine particles, alkanes, n-alkanoic acids and PAHs in air emitted from the Uigur style cooking are hundreds times higher than ambient PM2.5 in Beijing.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Culinária , Alcanos/análise , China , Monitoramento Ambiental , Tamanho da Partícula , Hidrocarbonetos Policíclicos Aromáticos/análise
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