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Wu J.,Xi'an University of Technology | Wu J.,Design Science | Xu C.,Hangzhou Environmental Monitoring Center Station | Xu C.,Shanghai Academy of Environmental science | And 2 more authors.
Atmosphere | Year: 2016

Continuous measurements of meteorological parameters, gaseous pollutants, particulate matters, and the major chemical species in PM2.5 were conducted in urban Hangzhou from 1 September to 30 November 2013 to study the potential sources and formations of PM2.5 pollution. The average PM2.5 concentration was 69 μg·m-3, ~97% higher than the annual concentration limit in the national ambient air quality standards (NAAQS) of China. Relative humidity (RH) and wind speed (WS) were two important factors responsible for the increase of PM2.5 concentration, with the highest value observed under RH of 70%-90%. PM2.5 was in good correlation with both NO2 and CO, but not with SO2, and the potential source contribution function (PSCF) results displayed that local emissions were important potential sources contributing to the elevated PM2.5 and NO2 in Hangzhou. Thus, local vehicle emission was suggested as a major contribution to the PM2.5 pollution. Concentrations of NO2 and CO significantly increased in pollution episodes, while the SO2 concentration even decreased, implying local emission rather than region transport was the major source contributing to the formation of pollution episodes. The sum of SO4 2-, NO3 -, and NH4 + accounted for ~50% of PM2.5 in mass in pollution episodes and the NO3 -/EC ratios were significantly elevated, revealing that the formation of secondary inorganic species, particularly NO3 -, was an important contributor to the PM2.5 pollution in Hangzhou. This study highlights that controlling local pollution emissions was essential to reduce the PM2.5 pollution in Hangzhou, and the control of vehicle emission in particular should be further promoted in the future. © 2016 by the authors.


Dai Q.,Nankai University | Li L.,Nankai University | Li T.,Nankai University | Bi X.,Nankai University | And 7 more authors.
Aerosol and Air Quality Research | Year: 2016

The atmospheric signature and potential sources of rare earth elements (REEs) in ambient particulate matter (PM) collected at urban (ZH) and background sites (ZWY) between February 2011 and January 2012 in the Yangtze River Delta region were investigated in this study. The average total concentrations of REEs for TSP, PM10 and PM2.5 were measured to be 11.98, 9.37, 2.24 ng m-3 in ZH, which were 1.9, 1.8, 1.3 times higher than those measured in ZWY. The size distribution pattern of the REEs shows that they are significantly fractionated into coarse particles (e.g., approximately 50% in PM2.5-10). However, La, Ce and Sm are even more enriched in PM with respect to each other and other REEs. It is also shown that Ce contamination is prevalent throughout the study area, which is particularly exemplified in the finer particulate matter fraction; this significant Ce contamination could be primarily attributed to vehicle emissions. Additionally, the REEs’ pollution events during the sampling campaign were identified by the time series of the REE ratios. And the contaminations of La, Sm and Ce show clearly wind-induced variations. The enrichment factors for REEs indicate that La, Ce, Nd and Sm originated from a mix of anthropogenic and natural emission sources with small EF values. © Taiwan Association for Aerosol Research.


Dai Q.,Nankai University | Li L.,Nankai University | Yang J.,Nankai University | Liu B.,Nankai University | And 5 more authors.
Environmental Science and Pollution Research | Year: 2016

Improved understanding of the fractionation and geochemical characteristic of rare earth elements (REEs) from steel plant emissions is important due to the unclear atmospheric signature of these elements and their adverse impact on human health and the environment. In this study, ambient particulate matter of different sizes was collected from one site in an integrated iron and steelmaking industrial zone (HG) and one urban background site with no direct industrial emissions (ZWY) during a 1-year sampling campaign in China. The total concentrations of REEs for TSP, PM10, and PM2.5 were 27.248, 14.989, 3.542 ng/m3 in HG and 6.326, 5.274, 1.731 ng/m3, respectively, in ZWY, which revealed the local influence of the steelmaking activities to the air quality. With respect to ZWY, the REEs in HG site are obviously fractionated in the coarser fraction, and LREEs account for more than 80 % of the total REE burden in all of the samples. Additionally, the REEs in HG and ZWY show a homogeneous trend with successively increased LREE/HREE ratios from the coarse particles to the fine particles. In our samples, La, Ce, Nd, and Sm are the most enriched rare earth elements, especially in the HG site. Moreover, ternary diagrams of LaCeSm indicate that the REEs in HG are potentially contributed by steelworks, carrier vehicles, coal combustion, and road dust re-suspension. © 2016 Springer-Verlag Berlin Heidelberg


Xu H.,Nankai University | Bi X.-H.,Nankai University | Feng Y.-C.,Nankai University | Lin F.-M.,Hangzhou Environmental Monitoring Center Station | And 4 more authors.
Environmental Monitoring and Assessment | Year: 2011

To understand the origin and chemical characteristics of precipitation in Hangzhou, rainwater samples were collected from June 2006 to May 2008. All samples were analyzed for pH, electrical conductivity, and major ions (NH 4 +, Ca 2+, Mg 2+, Na +, K +, SO 4 2, NO 3{-}, F -, and Cl -). Acidification of precipitation in Hangzhou was serious with volume-weighted mean pH value of 4.5, while frequency of acid rain was 95%. The calculated SO -{4 2 /NO 3{-} ratio in Hangzhou precipitation was 2.87, which indicated that the precipitation of Hangzhou belonged to sulfate-based acid rain. The results of acid neutralization analysis showed that not all the acidity in the precipi tation of Hangzhou was neutralized by alkaline constituents. The results of sea salt contribution analysis showed that nearly all SO 4 2, Ca 2+, and Mg 2+ and 33.7% of K + were of non-sea origins, while all Na + and Cl - and 66.3% of K + originated from sea sources. The principal component analysis which was used to analyze the sources of various ions indicated that chemical compositions of precipitation in Hangzhou mainly came from terrestrial sources, factory emissions, fuel wood burning, and marine sources. © 2011 Springer Science+Business Media B.V.


Yu H.-X.,Hangzhou Environmental Monitoring Center Station | Min H.,Zhejiang University | Lu Z.-M.,Zhejiang University
Journal of Coal Science and Engineering | Year: 2010

A new biofilter technology was used to control the methane concentration in the coal mine. The results indicate that the biofilter achieves a steady methane removal capacity of 1 470 mg/(L•h) after 30 days start-up. More than 90% of the methane can be removed with an empty bed retention time (EBRT) of 5.6 min when the inlet concentration of methane (IMC) is lower than 70 mg/L (10%, V/V) and about 80% when IMC is at 105 mg/L (15%, V/V). The biofilter is still a reliable method to control methane concentration as an auxiliary means to boost coal mine production safety together with aggrandized ventilation and drainage technologies, even though the removal efficiency of methane is not very satisfactory with a high IMC (>10%) or a short EBRT (<3.8 min). © 2010 The Editorial Office of Journal of Coal Science and Engineering (China) and Springer-Verlag Berlin Heidelberg.


Chang J.,Zhejiang University | Ren Y.,Zhejiang University | Shi Y.,Zhejiang University | Zhu Y.,Zhejiang University | And 4 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2012

VOCs (volatile organic compounds) are believed to have close relationships with the chemical composition and physical characteristics of the atmosphere. Biogenic VOCs (BVOCs) are more reactive than anthropogenic VOCs (AVOCs), can contribute to tropospheric ozone and secondary particle formation, and have indirect effects on climate change. Estimates of regional BVOC emissions are thus crucial input parameters of air quality models. However, most of the BVOC inventory work has concentrated on natural habitats in Europe, North America and some tropical regions. Although an increasing number of studies are being carried out in tropical and mid-latitude regions throughout Asia in recent years, few studies are concerned with humid subtropical areas, especially in urban areas. Here, a field survey of vegetation composition and distribution was conducted in a subtropical urban-rural complex, Greater Taizhou Area (28°01'-29°20' N,120°17'-121°56'E), Zhejiang Province. Different models were developed and used to estimate leaf biomass of the main tree species. BVOC were divided into isoprene, monoterpenes and other VOCs (OVOCs) and different algorithms were used calculate them separately. The isoprene emission rate data of the main tree species in this area was identified using a plant enclosure approach followed by a GC-PID analysis, while other emission data was compiled from measurements available in China. Tree distribution information, leaf biomass, plant emissions, and meteorological data were combined to investigate the BVOC emission intensity, temporal and spatial patterns and species features in Greater Taizhou Area. Results showed that the annual BVOC emissions of Taizhou in 2009 is 4. 6×10 10 g C. Isoprene, total monoterpenes and OVOCs emissions account for 93. 8%, 3. 5% and 2. 7%, respectively. In rural area, the emission intensity of bamboo forest (133. 8 t C·km -2·a -1) is two orders of magnitude higher than those of Pinus massoniana forest, Cunninghamia lanceolata forest and evergreen broad-leaved forests (0. 9, 0. 8, 0. 6 t C·km -2· a -1, respectively). So from the perspective of improving air quality, expansion of bamboo forests should be inhibited while increasing the proportion of evergreen broad -leaf forests. Within Taizhou city, the BVOC emission intensity of street and riparian trees is 2. 4 t C·km -2· a -1, while the emission intensity of trees in parks and residential areas is 1. 6 t C·km -2· a -1, both of which are higher than that of any rural forest types other than bamboo forest. Among the primary tree species within the built-up area, Salix babylonica, Albizia julibrissin, Sophora japonica and Liquidambar formosana exhibited high BVOC emission potential, while Cinnamomum camphora, Magnolia grandiflora and Ginkgo biloba have relatively low emission potential. There were no significant differences in the emission patterns between native and nonnative tree species in Taizhou area. Species with low BVOC emission potential should therefore be chosen for future in urban greening initiatives. The annual BVOC emissions of Taizhou are much higher than those of Beijing (1. 6×10 10 g C/ a) and Hong Kong (1. 6×10 10 g C/ a) because these areas vary in climate and vegetation characteristics. This study also provides a scientific basis for the selection of tree species and improvement of air quality in cities in similar climate zones as Taizhou.


Dai Q.-L.,Nankai University | Bi X.-H.,Nankai University | Wu J.-H.,Nankai University | Zhang Y.-F.,Nankai University | And 5 more authors.
Aerosol and Air Quality Research | Year: 2015

The purpose of this study is to characterize heavy metals in ambient PM10 (particles with aerodynamic diameter below 10 μm) and PM2.5 (particles with aerodynamic diameter below 2.5 μm) particles in a typical integrated iron and steel industry zone (HG) and a background site (ZWY) during February 2011 to January 2012 in the Yangtze River Delta (YRD) region, China. Twelve elements were measured to study their levels, size distribution and sources. At the two sampling sites, Fe was found as the dominated metal in the total detected metals in both particle sizes, followed by Zn and Pb. They were regarded as the marker elements of iron and steel production emission along with Cr and Mn. The concentrations of all measured heavy metals in HG were 1–3.53 times higher than those measured in ZWY. When compared with previous studies, the concentrations of steel related elements (Fe, Zn, Mn) in this work were significantly high. The highest correlation coefficient was observed in HG for Fe and Zn. Additionally, Cd was found as the most enriched heavy metal by the enrichment factor analysis, followed by Zn, Pb, and Cu. The main sources contributing to heavy metals at HG site were identified by principle component analysis: steel dust (including coal combustion of coal-fired power plant, coke making and steel making emission), vehicle emission and road re-suspension dust and soil dust. Besides, steel dust was also found as the possible source of heavy metals at ZWY site. The result suggested the steel dust has influence on the whole study area. © Taiwan Association for Aerosol Research.


Ying F.,Hangzhou Environmental Monitoring Center Station | Ying F.,Zhejiang University | Bao Z.,Hangzhou Environmental Monitoring Center Station | Yang C.,Hangzhou Environmental Monitoring Center Station | And 4 more authors.
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2012

Volatile organic compounds (VOCs) in the ambient air were measured around main types of urban traffic roads (tunnel, expressway, trunk road and brach) from October 2010 to July 2011 in Hangzhou, China. The results showed that VOC concentration around the traffic roads was much higher than that in scenic spot, and the concentration decreased with the decrease of vehicle flow rate. Source apportionment results indicated that the VOCs in Hangzhou mainly came from anthropogenic sources, including vehicle emission, solvent evaporation, biomass fuel and coal burning. The VOCs around the traffic roads were mainly influenced by vehicle emissions, while the VOCs in scenic spot were more readily impacted by biomass fuel or coal burning. The concentration and chemical reactivity of VOCs around expressway was the highest in summer and lowest in spring, which was influenced by vehicle emissions, temperature, biogenic VOC and topographic conditions. Alkenes and aromatic compounds from the vehicle emissions contributed more than 80% of the VOCs reactivity in the air around all kinds of the traffic roads, suggesting that the VOCs reactivity in ambient air in Hangzhou was determined mainly by vehicle emissions. In summer and autumn, the emission of isoprene from plants increased the VOCs reactivity in the air around roads remarkably.


Xie H.,Zhejiang GongShang University | Ren M.,Zhejiang GongShang University | Lei Q.,Zhejiang University | Fang W.,Zhejiang University | Ying F.,Hangzhou Environmental Monitoring Center Station
Journal of Physical Chemistry C | Year: 2012

Rhodium has been proved to possess unique reactivity to convert NO x into N 2 with high conversion efficiency and selectivity. In this study, we have carried out DFT calculations on the reaction mechanism in the reduction of NO by CO on the surface of the Rh 7 + cluster. The calculated results suggest that the reaction proceeds via three steps. First, the NO and CO are adsorbed on the Rh 7 + cluster, then the adsorbed NO decomposes to N and O atoms. The O atom reacts with the adsorbed CO leading to the formation of CO 2 molecule. Second, another NO is adsorbed on the rhodium cluster and decomposes to N and O atoms, then the two N atoms couple with each other to yield N 2 molecule. Finally, the second CO can be adsorbed on the Rh 1 or Rh 7 atom of the Rh 7 + cluster and oxidized to CO 2 molecule. On the basis of present calculations from gas-phase Gibbs free energy profiles, the reaction path related to CO adsorption on the Rh 7 atom is energetically more favorable. The second adsorbed NO generating N and O atoms in the second step is the rate-limiting step of whole catalytic cycle. The high activation barrier (TS 67) of 56.6 kcal/mol can be driven by large exergonic reaction. Our work would provide some valuable fundamental insights into the reaction mechanism between NO and CO on the rhodium surface, which is vitally important to decrease NO emissions in automotive exhaust gas. © 2012 American Chemical Society.


Chen J.,Zhejiang University | Chen J.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control | Liu Y.-M.,Hangzhou Environmental Monitoring Center Station | Zhang J.-Y.,Zhejiang University | Zhang J.-Y.,Zhejiang Province Key Laboratory of Organic Pollution Process and Control
Chinese Journal of Applied Ecology | Year: 2014

Species sensitivity distributions (SSDs) methods in both forward and reverse modes were used to evaluate the ecological risk and determine the contaminant concentration threshold for the protection of aquatic species and ecological quality. In this study, the existing toxicity data of freshwater organisms were fitted to SSD functions to estimate the hazardous concentrations for 5% of the species (HC5) for microcystins, ammonia and nitrite, and the ecological risk of their mixtures. The potentially affected fractions (PAFs) of various concentrations of microcystins, ammonia and nitrite were also calculated. Results showed that microcystins exhibited a higher ecological risk than ammonia and nitrite. The HC5 value for microcystins exposure was 19.22 μg·L-1 whereas the HC5 values for ammonia and nitrite exposure were 6583.94 μg·L-1 and 334.33 μg·L-1, respectively. The sensitivity of freshwater organisms varied with exposed concentrations of microcystins, ammonia and nitrite. Crustaceans were more sensitive than fishes to microcystins, and less sensitive than fishes to nitrite when the concentrations of microcystins and nitrite were below 125.04 μg·L-1 and 2989.40 μg·L-1, respectively, and vice versa when exposed to higher concentrations of microcystins and nitrite. No significant difference was observed for the sensitivities of fishes and crustaceans exposed to ammonia. In studies with selected lakes in China, our results showed that the ecological risk in both Tai and Hongfeng lakes exceeded the permissible HC5 threshold, and the multiple substance potentially affected fractions (msPAFs) of microcystins, ammonia and nitrite were 2.6%-5.6%, indicating that the ecological risk of their mixtures was more threatening than each individual contaminant being investigated.

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