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Xu B.,Peking University | Xu B.,Zhejiang Province Environmental Monitoring Center | Zhu T.,Peking University | Tang X.,Peking University | Shang J.,Peking University
Science China Chemistry | Year: 2010

The heterogeneous reaction of formaldehyde (HCHO) on the surface of titanium dioxide (TiO2) was investigated in situ using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) combined with ion chromatography (IC), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Formate, dioxymethylene, methoxy, and polyoxymethylene were observed in the infrared spectra of TiO2 particles during the reaction. On the surface of TiO2, the adsorbed HCHO was first oxidized to dioxymethylene and further oxidized to formate. The effects of temperature and ultraviolet radiation (UV) on the reaction products and reactive uptake coefficients were studied, and the results indicate that the reaction rate can be accelerated at increasing temperatures as well as under UV. The heterogeneous reaction mechanisms of HCHO on the surface of TiO2 in the dark and under UV irradiation are proposed. Kinetic measurements show that formate formation on TiO2 is second order in HCHO concentration and the initial reactive uptake coefficients at room temperature calculated with the Brunauer-Emmett- Teller specific surface area are (0.5-5) × 10 -8 ([HCHO]: 1 × 1013-2 × 1014 molecules/cm3). A linear function relationship exists between the uptake coefficient and the concentration. The apparent activation energy of the reaction was also determined. © 2010 Science China Press and Springer-Verlag Berlin Heidelberg.

Xu B.,Peking University | Xu B.,Zhejiang Province Environmental Monitoring Center | Shang J.,Peking University | Zhu T.,Peking University | Tang X.,Peking University
Atmospheric Environment | Year: 2011

Formaldehyde is one of the most important carbonyl organic compounds. Heterogeneous reactions of formaldehyde on the surface of oxides of crustal elements could be an important sink for formaldehyde in the atmosphere. In this study, the kinetics of the heterogeneous reaction of formaldehyde on the surface of γ-Al2O3 was investigated in situ by diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) combined with ion chromatography (IC), X-ray diffraction (XRD), and field emission environmental scanning electron microscope (ESEM). The adsorbed species, formate, dioxymethylene, polyoxymethylene, and formaldehyde, on γ-Al2O3 particles, were identified by infrared spectroscopy. On the surface of γ-Al2O3 particles, formaldehyde is first oxidized to dioxymethylene, which is further oxidized to formate. The reaction order was determined as 0.74 ± 0.05, and the initial reactive uptake coefficients at room temperature were calculated with the geometric and Brunauer-Emmett-Teller specific surface areas as (3.6 ± 0.8) × 10-4 and (1.4 ± 0.31) × 10-8, respectively. The influences of oxygen concentration, humidity, and temperature on the reaction products and reactive uptake coefficients were studied. The results indicated the reaction is independent of the O2 concentration within the range used in this experiment, and humidity is negatively correlated with the uptake of formaldehyde by the particles. Temperature not only plays a role on the heterogeneous reaction products but also is positively correlated with the uptake rate of formaldehyde by γ-Al2O3 particles in the troposphere. The apparent activation energy of the reaction was determined. © 2011 Elsevier Ltd.

Huang X.-F.,University of Science and Technology of China | Xue L.,University of Science and Technology of China | Tian X.-D.,Zhejiang Province Environmental Monitoring Center | Shao W.-W.,Zhejiang Province Environmental Monitoring Center | And 6 more authors.
Atmospheric Environment | Year: 2013

The Yangtze River Delta (YRD) region is one of the most economically developed regions of China and characterized by high level of urbanization, which comes with the consequence of severe deterioration of its atmospheric environment in a large regional scale. In order to characterize the fine particle pollution features representative for YRD, especially for the abundant and complex carbonaceous component, we deployed advanced on-line measurement at a regional site in Jiaxing in the central YRD area during June 29-July 15 (the summer campaign) and December 11-23 (the winter campaign), with a high resolution aerosol mass spectrometer (AMS) and a single particle soot photometer (SP2). The mean PM1 mass concentration was observed to be 32.9 μg m-3 in summer, with organic matter (OM) and black carbon (BC) contributing 32.1 and 9.1%, respectively, and 41.9 μg m-3 in winter, with OM and BC contributing 30.3 and 16.9%, respectively. The O/C ratio of OM, an indicator for the oxidation level of organic aerosol, was calculated to be 0.28 in summer and 0.33 in winter, and the number fraction of internally mixed BC particles (NIB), an indicator for the aging level of BC, was calculated to be 0.51 in summer and 0.53 in winter. Two popular independent methods were used to estimate the amount of secondary organic aerosol (SOA) in Jiaxing: one is the positive matrix factorization method utilizing the high resolution aerosol mass spectra (the AMS-PMF method), and the other is the simple OC/EC ratio method (the OC/EC method). The AMS-PMF method estimated that SOA averagely accounted for 68.3 and 30.2% of OM in summer and winter, respectively. The SOA amount estimated by the OC/EC method was found to agree well with that by the AMS-PMF method in summer, but strong biomass burning events in winter made the OC/EC method over-estimate SOA largely. The seasonal variation of SOA indicates that SOA production in YRD is more determined by ambient temperatures than by precursors. © 2012 Elsevier Ltd.

Li Y.,Peking University | Li Y.,Chinese Academy of Meteorological Sciences | Zhu T.,Peking University | Zhao J.,CAS Institute of Chemistry | Xu B.,Zhejiang Province Environmental Monitoring Center
Environmental Science and Technology | Year: 2012

Quinones are toxicological substances in inhalable particulate matter (PM). The mechanisms by which quinones cause hazardous effects can be complex. Quinones are highly active redox molecules that can go through a redox cycle with their semiquinone radicals, leading to formation of reactive oxygen species. Electron spin resonance spectra have been reported for semiquinone radicals in PM, indicating the importance of ascorbic acid and iron in quinone redox cycling. However, these findings are insufficient for understanding the toxicity associated with quinone exposure. Herein, we investigated the interactions among anthraquinone (AQ), ascorbic acid, and iron in hydroxyl radical (·OH) generation through the AQ redox cycling process in a physiological buffer. We measured ·OH concentration and analyzed the free radical process. Our results showed that AQ, ascorbic acid, and iron have synergistic effects on ·OH generation in quinone redox cycling; i.e., ascorbyl radical oxidized AQ to semiquinone radical and started the redox cycling, iron accelerated this oxidation and enhanced ·OH generation through Fenton reactions, while ascorbic acid and AQ could help iron to release from quartz surface and enhance its bioavailability. Our findings provide direct evidence for the redox cycling hypothesis about airborne particle surface quinone in lung fluid. © 2012 American Chemical Society.

Wu D.-H.,Nanjing Agricultural University | Yu H.-Y.,Zhejiang Province Environmental Monitoring Center | Wu H.-Y.,Nanjing Agricultural University | Zhou B.,Zhejiang Province Environmental Monitoring Center | Wang B.X.,Nanjing Agricultural University
Chinese Journal of Applied Ecology | Year: 2010

Water eutrophication is a global problem, and one of the major environmental problems in China. At present, its studies in China are mainly focused on lakes and reservoirs, whereas a few on rivers. Based on the stress-response of benthic macroinvertebrate assemblages to water nutrients, we used the nonparametric deviance reduction (change point analysis) to compute the breakpoints of nutrients concentrations, in the upper reaches of Xitiao Stream in Zhejiang. The results indicated that the breakpoints of total nitrogen (TN) and total phosphors (TP) were 1. 409 mg · L-1 and 0. 033-0. 035 mg · L-1, respectively. The TN and TP concentrations at reference sites were lower, while those at urban sewage-polluted sites were higher than the thresholds. In latter ease, a serious degradation of benthic macroinvertebrates assemblages could be induced. To establish water nutrients criteria with relation to aquatic organisms would make the biological monitoring play a full role in water management, and provide scientific data to estimate the total maximum daily load (TMDL) of TN and TP in water body.

Jiang F.,Nanjing University | Zhou P.,Meteorological Bureau | Liu Q.,Hong Kong Polytechnic University | Wang T.,Nanjing University | And 2 more authors.
Journal of Atmospheric Chemistry | Year: 2012

In this study, we investigate the springtime O3 formation over East China (April 2008) using the Weather Research and Forecasting Model with Chemistry (WRF/Chem). A simple process analysis scheme is added to WRF/Chem, which could calculate the contributions of photochemical and physical processes to O3 formation. WRF/Chem calculates the hourly 3-D O3 mixing ratios, photochemical O3 production rates (CPR) and physical processes contribution rates (PCR) on a two nested domain system, with inner domain focusing on East China. Model evaluation shows that the modeled results agree relatively well with the observations. On the ground level, the high O3 mixing ratios (>45 ppbv) are located over Fujian and Jiangxi provinces. The O3 levels over the Yangtze River Delta (YRD) and northern Jiangsu are low (<30 ppbv). The distribution patterns of CPR and PCR over East China reveal that the high O3 mixing ratios over Jiangxi and Fujian are caused by both local photochemical generation and regional transport, while the O3 concentrations over the YRD region are transported and diffused from surrounding areas. In addition, the contributions of biogenic and anthropogenic emissions as well as the regional transport from domain's upstream regions are discussed. On average, the biogenic and anthropogenic emissions account for 2.6 and 4.5 ppbv of daytime mean O 3 mixing ratios in East China, respectively. © 2012 Springer Science+Business Media Dordrecht.

PubMed | Zhejiang Agriculture And forestry University, Zhejiang Province Environmental Monitoring Center, University of Houston-Clear Lake and Zhejiang University
Type: | Journal: The Science of the total environment | Year: 2016

Phthalate esters (PAEs) are widely used as plasticizers and have become one of the emerging contaminants with an increasing public concern. The residues of PAEs frequently co-exist with heavy metals such as cadmium (Cd) in waters; however, their joint ecotoxicity remains largely unknown. We herein investigated the single and joint toxicity of commonly used PAEs and Cd using freshwater luminescent bacteria Vibrio qinghaiensis sp.-Q67. The median effective concentration (EC

PubMed | University Institute of Health Sciences, Zhejiang Province Environmental Monitoring Center, University of Houston-Clear Lake and Zhejiang University
Type: Journal Article | Journal: Environmental pollution (Barking, Essex : 1987) | Year: 2016

Benzotriazole ultraviolet stabilizers (BUVSs) are prominent chemicals widely used in industrial and consumer products to protect against ultraviolet radiation. They are becoming contaminants of emerging concern since their residues are frequently detected in multiple environmental matrices and their toxicological implications are increasingly reported. We herein investigated the antiandrogenic activities of eight BUVSs prior to and after human CYP3A4-mediated metabolic activation/deactivation by the two-hybrid recombinant human androgen receptor yeast bioassay and the invitro metabolism assay. More potent antiandrogenic activity was observed for the metabolized UV-328 in comparison with UV-328 at 0.25M ((40.734.90)% vs. (17.123.00)%), showing a significant metabolic activation. In contrast, the metabolized UV-P at 0.25M resulted in a decreased antiandrogenic activity rate from (16.080.95)% to (6.912.64)%, indicating a metabolic deactivation. Three mono-hydroxylated (OH) and three di-OH metabolites of UV-328 were identified by ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS/MS), which were not reported previously. We further surmised that the hydroxylation of UV-328 occurs mainly at the alicyclic hydrocarbon atoms based on the in silico prediction of the lowest activation energies of hydrogen abstraction from C-H bond. Our results for the first time relate antiandrogenic activity to human CYP3A4 enzyme-mediated hydroxylated metabolites of BUVSs. The biotransformation through hydroxylation should be fully considered during the health risk assessment of structurally similar analogs of BUVSs and other emerging contaminants.

Tang Y.-D.,Environmental Engineering Co. | Feng Y.-Q.,Zhejiang Province Environmental Monitoring Center
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2010

Dynamic test signals of a pile with the wavelet method were analyzed. The traditional testing data of stress wave reflection were used. More information about propagating process of stress wave in the pile was obtained by getting ride of errors from the actual measured signals. The results of some examples demonstrated that the proposed method has better accuracy and flexibility.

PubMed | Zhejiang Province Environmental Monitoring Center and Hangzhou Normal University
Type: Journal Article | Journal: European journal of mass spectrometry (Chichester, England) | Year: 2016

p-Chloroaniline is one of the banned aromatic amines in azo dyes, but it is very difficult to distinguish it from its isomers due to their identical retention time in chromatography and similar mass spectra. In this work, derivatization of the isomeric chloroanilines was carried out to yield the corresponding N-tosyl chloroanilines, which were completely separated by gas chromatography and also possessed clearly different electron ionization mass spectra. Thus, the three isomers could be differentiated and determined at the same time. Density functional theory calculation results indicated that the effect of the substituent pattern in electron ionization mass spectrometry is mainly due to the difference in the stability of the product ion (P2) at m/z 126, originating from the loss of tosyl radical from the precursor ion.

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