Six hydrophobic and hydrophilic fractions were isolated using XAD-8 and XAD-4 resins, and were extensively characterized. Partition coefficients of perylene, pbenanthrene and anthracene binding to the six fractions we...
详细信息
Six hydrophobic and hydrophilic fractions were isolated using XAD-8 and XAD-4 resins, and were extensively characterized. Partition coefficients of perylene, pbenanthrene and anthracene binding to the six fractions were determined by fluorescence quenching titration. The Kdo~ values obtained for the polycyclic aromatic hydrocarbons （PAHs） binding to the hydrophobic fractions were larger than those to the hydrophilic fractions. Nonlinear Stem-Volmer plots were observed when binding phenanthrene and anthracene to some hydrophilic fraction samples, suggesting saturation of polar interaction binding sites. A significant correlation of logKdo~ values with molecular weights and molar absorptivities at 280 nm was observed, while atomic ratio of C/t-I was found to be a poor indicator for aromaticity. Other structural descriptors such as paraffinic carbon and polarity influenced the DOM-fraction ability to bind PAHs. Different interaction mechanisms underlying binding of the different fractions to the PAHs were also discussed.
With XAD-series and ion exchange resins, dissolved organic matter （DOM） from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid （HA）, fulvic acid （FA）, hydrophobic neutra...
详细信息
With XAD-series and ion exchange resins, dissolved organic matter （DOM） from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid （HA）, fulvic acid （FA）, hydrophobic neutrals （HON）, hydrophilic acids （HIA）, hydrophilic bases （HIB） and hydrophilic neutrals （HIN）. Those fractions were characterized by high performance size exclusion chromatography, fluorescence spectroscopy and UV absorbance. Among the 6 fractions, FA was predominant and accounted for 51% of the total DOM. The weight-average （Mw） and number-averaged （Mn） molecular weight of these fractions ranged from 1688 to 2355 Da and from 1338 to 1928 Da, respectively. A strong correlation was observed between specific UV absorbance at 280 nm, E2/E3 （absorbance at 250 nm to 365 nm）, and the molecular weight for DOM fractions. UV-Vis fulvic-like fluorescence peaks were found in all fractions. Proteinlike fluorescence peaks existed in HON may indicate that microbial activity was severely in Lake Hongfeng. There was a significant relationship between fluorescence intensities and specific UV absorbance at 254 nm for those DOM fractions, suggesting their similar luminescence characteristics. The values of fluorescence index （f450/500） indicated that hydrophobic fractions may derive from terrestrial sources, and the hydrophilic fractions from microbial and terrestrial origins. Those results suggest that there were inter-relationships between molecular weight, fluorescence and absorbance characteristics, and also subtle consistencies between the hydrophilic and hydrophobic properties and the sources for these 6 fractions from Lake Hongfeng.
The aim of this work was to establish a Dynamic Dilution Olfactometer, basement of research was national standard GB/T14675-93 and European standard En13725, core process of gas pipeline was flow-mixing of the odor an...
详细信息
The aim of this work was to establish a Dynamic Dilution Olfactometer, basement of research was national standard GB/T14675-93 and European standard En13725, core process of gas pipeline was flow-mixing of the odor and the pure gas by many MFCs, and compiled automation control software based on the LabVIEW programming language, realized functions of automatic control test schedule and determination of odor. The results show that on the calibration experiment to the dynamic olfactometer by the different concentration CO tracing gas, instrumental instability average Id of all dilution step is 0.92%, instrumental accuracy average Ad is 7.2%, meet to and smaller than European standard Id5% and Ad20%.
Poly（vinylpyridine） WH-225 resin was prepared and characterized. Compared with the commercial hypercrosslinked adsorbent NDA-100 and macroporous adsorbent XAD-4 resins, the newly synthesized poly（vinylpyridine） WH...
详细信息
Poly（vinylpyridine） WH-225 resin was prepared and characterized. Compared with the commercial hypercrosslinked adsorbent NDA-100 and macroporous adsorbent XAD-4 resins, the newly synthesized poly（vinylpyridine） WH-225 resin exhibited the highest adsorption capacity toward SIPA from aqueous solution.
In order to provide basic data for practical application,photodegradation experiment of Nnitrosodimethylamine(NDMA)in aqueous solution was carried out with a low-pressure Hg *** of the initial concentration of NDMA,so...
详细信息
In order to provide basic data for practical application,photodegradation experiment of Nnitrosodimethylamine(NDMA)in aqueous solution was carried out with a low-pressure Hg *** of the initial concentration of NDMA,solution pH,dissolved oxygen,and the presence of humic acid on NDMA photodegradation were *** at various initial concentrations selected in this study was almost completely photodegraded by UV irradiation within 20 min,except that at 1.07 mmol/L,NDMA could be photodegraded almost completely in the acidic and neutral solutions,while the removal efficiency decreased remarkably in the alkaline *** oxygen enhanced the NDMA photodegradation,and the presence of humic acid inhibited the degradation of *** on the initial concentration of NDMA,NDMA photodegradation by UV obeyed the pseudo-first-order ***,nitrite,and nitrate were detected as the photodegradation products of NDMA.^(1)O_(2) was found to be the reactive oxygen species present in the NDMA photodegradation process by UV,based on the inhibiting experiments using tert-butanol and sodium azide.
During 2005, the filter samples of ambient PM10 from five sites and the source samples of particulate matter were collected in Kaifeng, Henan Province of China. Nineteen elements, water-soluble ions, total carbon （TC...
详细信息
During 2005, the filter samples of ambient PM10 from five sites and the source samples of particulate matter were collected in Kaifeng, Henan Province of China. Nineteen elements, water-soluble ions, total carbon （TC） and organic carbon （OC） contained in samples were analyzed. Seven contributive source types were identified and their contributions to ambient PM10 were estimated by chemical mass balance （CMB） receptor model. Weak associations between the concentrations of organic carbon and element carbon （EC） were observed during the sampling periods, indicating that there was secondary organic aerosol pollution in the urban atmosphere. An indirect method of ＂OC/EC minimum ratio＂ was applied to estimate the concentration of secondary organic carbon （SOC）. The results showed that SOC contributed 26.2%, 32.4% and 18.0% of TC in spring, summer-fall and winter, respectively, and the annual average SOC concentration was 7.07 μg/m^3, accounting for 5.73% of the total mass in ambient PM10. The carbon species concentrations in ambient PM10 were recalculated by subtracting SOC concentrations from measured concentrations of TC and OC to increase the compatibility of source and receptor measurements for CMB model.
Based on,but not limited to the research results of electrical engineering published in the special issue of Science in China Series E,June 2008,this essay gives a brief review on a wide range of state-of-art advancem...
详细信息
Based on,but not limited to the research results of electrical engineering published in the special issue of Science in China Series E,June 2008,this essay gives a brief review on a wide range of state-of-art advancement in electrical engineering field of China,which includes power system modeling,analysis and control,risk assessments in power system,etc.
PM2.5 samples were collected at urban, industrial and coastal sites in Tianjin during winter, spring and summer in 2007. Concentrations of elemental carbon （EC） and organic carbon （OC） were analyzed using the IMPR...
详细信息
PM2.5 samples were collected at urban, industrial and coastal sites in Tianjin during winter, spring and summer in 2007. Concentrations of elemental carbon （EC） and organic carbon （OC） were analyzed using the IMPROVE thermal-optical reflectance （TOR） method. Both OC and EC exhibited a clear seasonal pattern with higher concentrations observed in the winter than in the spring and summer, due to cooperative effect of changes in emission rates and seasonal meteorology. The concentrations of carbonaceous species were also influenced by the local factors at different sampling sites, ranking in the order of industrial〉 urban 〉 coastal during winter and spring. In the summer, the port emissions, enriched with EC, had a significant impact on carbonaceous aerosols at the coastal site. Total carbonaceous aerosol accounted for 40.0% in winter, 33.8% in spring and 31.4% in summer of PM2.5 mass. Good correlation （R = 0.84-0.93） between OC and EC indicated that they had common dominant sources of combustion such as coal burning and traffic emissions. The daily average OC/EC ratios ranged from 2.1 to 9.1, the elevated OC/EC ratios being found in the winter. The estimated secondary organic carbon （SOC） accounted for 46.9%, 35.3% and 40.2% of the total OC in the winter, spring and summer, respectively, indicating that SOC may be an important contributor to fine organic aerosol in Tianjin.
暂无评论