Volatile organic compounds(VOCs)were measured at six sites in Beijing in August,*** to 148 VOC species,including C_(3) to C_(12) alkanes,C_(3) to C_(11) alkenes,C_(6) to C_(12) aromatics,and halogenated hydrocarbons,w...
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Volatile organic compounds(VOCs)were measured at six sites in Beijing in August,*** to 148 VOC species,including C_(3) to C_(12) alkanes,C_(3) to C_(11) alkenes,C_(6) to C_(12) aromatics,and halogenated hydrocarbons,were *** the concentrations differed at the sites,the chemical compositions were similar,except for the Tongzhou site where aromatics were significantly high in the *** on the source profiles measured from previous studies,the source apportionment of ambient VOCs was preformed by deploying the chemical mass balance(CMB)*** results show that urban VOCs are predominant from mobile source emissions,which contribute more than 50% of the VOCs(in mass concentrations)to ambient air at most *** important sources are gasoline evaporation,painting,and *** exception is at the Tongzhou site where vehicle exhaust,painting,and solvents have about equal contribution,around 35% of the ambient VOC *** the receptor model is not valid for deriving the sources of reactive species,such as isoprene and 1,3-butadiene,other methodologies need to be further explored.
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 ...
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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 （PMzs） 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. 13-Sitostrol also made up relatively a large fraction of PMz5 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.
Taking two typical rivers in high mountains and steep gorge areas as example,this paper analyzes the spetiotemporal variability of the eco-hydrological characteristics and the driving forces leading to ***,based on th...
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Taking two typical rivers in high mountains and steep gorge areas as example,this paper analyzes the spetiotemporal variability of the eco-hydrological characteristics and the driving forces leading to ***,based on the species-environmental data processing,this paper adopts canonical correspondence analysis(CCA)method to identify the environmental factors influencing the distribu- tion of river bank ***,this study uses the ecological diversity Index to represent the spatiotemporel variability of ecological ***,this paper uses the multiple correlation method to analyze the relationship between the hydrological factors and meteorological factors,and to identify the key factors leading to the hydrological regime *** last,based on the analysis of basin water quality data,this paper analyzes the regularity of spatiotemporal variability and its driving *** the systematic analysis on the outcome,we could get that the spatiotemporel distribution of eco-hydrological characteristics shows the regular changes from the upstream to downstream(from the north to the south),and the spatiotemporal variability of eco-hydrological characteristics is typical from the east to the ***,aspect and water distribution are the primary natural driving forces leading to the spatiotemporel variability of eco-hydrological characteristics;and exploitation and op- eration of hydroelectric power station,construction of road on the river bank,and basin land utilization are the main human driving forces.
The present work studied the influence of glucose feeding on the ligninolytic enzyme production of Phanerochaete chrysosporium in a nitrogen-limited(C/N ratio is 56/8.8 mmol/L)*** sets of shaking flask experiments wer...
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The present work studied the influence of glucose feeding on the ligninolytic enzyme production of Phanerochaete chrysosporium in a nitrogen-limited(C/N ratio is 56/8.8 mmol/L)*** sets of shaking flask experiments were *** results showed that 2 g/L glucose feeding on the first day of the culture(24 h after the inoculation)stimulated both fungal biomass growth and enzyme *** manganese peroxidase(MnP)activ-ity was 2.5 times greater than that produced in cultures with-out glucose ***,the glucose feeding mode in fed-batch culture was also *** to cul-tures with glucose feeding every 48 h,cultures with glucose feeding of 1.5 g/L(final concentration)every 24 h produced more *** peak and total yield of MnP activity were 2.7 and 3 times greater compared to the contrast culture,respectively,and the enzyme was kept stable for 4 days with an activity of over 200 U/L.
fouling online in an anaerobic membrane bioreac-tor(AMBR).Short-term running experiments were carried out under different operating conditions to explore feasible ultrasonic *** experimental results indicated that whe...
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fouling online in an anaerobic membrane bioreac-tor(AMBR).Short-term running experiments were carried out under different operating conditions to explore feasible ultrasonic *** experimental results indicated that when the crossflow velocity was more than 1.0 m/s,mem-brane fouling could be controlled effectively only by hydro-dynamic methods without *** ultrasound was applied,an ultrasonic power range of 60-150 W was suitable for the membrane fouling control in the experimental *** experimental results showed that the membrane fouling was controlled so well that membrane filtration resistance(ΣR)could stay at 5×10^(11)m^(−1) for more than a week with the crossflow velocity of 0.75 m/s,which equaled the effect of crossflow velocity of more than 1.0 m/s without ultrasound.
Agricultural activity is one of the most important sources of aerosol *** understand the mass distribu-tion and sources of aerosol particles and their inorganic water-soluble ions in a suburb farmland of Beijing,parti...
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Agricultural activity is one of the most important sources of aerosol *** understand the mass distribu-tion and sources of aerosol particles and their inorganic water-soluble ions in a suburb farmland of Beijing,particle samples were collected using a microorifice uniform deposit impactor(MOUDI)in the summer of 2004 in a suburb vege-table *** distribution of the particles and their inor-ganic water-soluble ions in the diameter range of 0.18-18 mm were *** dominant fine particle ions were SO_(4)^(2−),NO^(3−),and NH_(4)^(+).The association of day-to-day variation of the concentration of these ions with temperature,humidity,and solar radiation suggested that they are formed by the reac-tion of NH_(3) released from the vegetable field with the acid species produced from photochemical *** particle K+is likely from vegetation emission and biomass *** particles like Ca^(2+),Mg^(2+),NO_(3)^(−),and SO_(4)^(2−)are sug-gested to come from the mechanical process by which the soil particle entered the atmosphere,and from the reaction of the acid species at the surface of the soil *** results show that fertilizer and soil are important factors determining the aerosol particle over agricultural fields,and vegetable fields in suburban Beijing contribute significantly to the aerosol particle.
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