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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 Source

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. Source

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. Source

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. Source

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. Source

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