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131.
132.
Jianjun Chen Qi Ying Michael J. Kleeman 《Atmospheric environment (Oxford, England : 1994)》2010,44(10):1331-1340
The UCD/CIT air quality model with the Caltech Atmospheric Chemistry Mechanism (CACM) was used to predict source contributions to secondary organic aerosol (SOA) formation in the San Joaquin Valley (SJV) from December 15, 2000 to January 7, 2001. The predicted 24-day average SOA concentration had a maximum value of 4.26 μg m?3 50 km southwest of Fresno. Predicted SOA concentrations at Fresno, Angiola, and Bakersfield were 2.46 μg m?3, 1.68 μg m?3, and 2.28 μg m?3, respectively, accounting for 6%, 37%, and 4% of the total predicted organic aerosol. The average SOA concentration across the entire SJV was 1.35 μg m?3, which accounts for approximately 20% of the total predicted organic aerosol. Averaged over the entire SJV, the major SOA sources were solvent use (28% of SOA), catalyst gasoline engines (25% of SOA), wood smoke (16% of SOA), non-catalyst gasoline engines (13% of SOA), and other anthropogenic sources (11% of SOA). Diesel engines were predicted to only account for approximately 2% of the total SOA formation in the SJV because they emit a small amount of volatile organic compounds relative to other sources. In terms of SOA precursors within the SJV, long-chain alkanes were predicted to be the largest SOA contributor, followed by aromatic compounds. The current study identifies the major known contributors to the SOA burden during a winter pollution episode in the SJV, with further enhancements possible as additional formation pathways are discovered. 相似文献
133.
Ultrafine particles (UFPs) released from laser printers are electrostatically charged during the working processes of the devices, and the electrostatic force can obviously influence the dynamics of the particles. Due to the measurement difficulty and scarcity of relevant research, this issue was not reported. This study tried to address this issue through experimental measurement of the surface charge of UFPs and numerical investigation on the influence of electrostatic force on the dynamics of UFPs. A test chamber was set up to collect the UFPs, and the Scanning Electron Microscope was used to observe the morphologies of the UFPs. Based on the particle diameter and surface zeta potential, the surface charge of UFPs was calculated. The measurement results gave that particle emitted from laser printers are negatively charged and the average surface charge of particle emissions for four laser printers is in a range of about ?4.16 × 10?17 to ?6.07 × 10?17 C (~?260 to ?379 e). This paper also discussed the influence of electrostatic force on the dynamics of UFPs. According to the numerical investigation, it was found that, in the absence of electric field, the electrostatic force has to be considered when the surface charge is larger than 1 × 10?16 C and when the UFP is very close to the wall with a distance of less than 0.01 m. These findings will guide constructively in predicting the dispersion and deposition of particles emitted from laser printers. 相似文献
134.
光/电Fenton牺牲阳极法降解有机污染物 总被引:2,自引:1,他引:1
采用Fe片为阳极和石墨为阴极,在可见光(λ450 nm)照射并外加电压条件下,以有机染料橙Ⅱ(orangeⅡ)及有机无色小分子2,4-二氯苯酚(2,4-dichlorophenol,DCP)为目标化合物,探讨了光/电Fenton牺牲阳极法降解有机污染物的最佳反应条件,结果表明,在电压=3 V,pH=3.0,H2O2浓度为5×10-5mol/L时,orangeⅡ的降解效果最好,反应10 h矿化率可达到78%,210 min内2,4-DCP降解率为91.4%。通过对光/电Fenton体系原位循环伏安参数测定及过氧化物酶催化反应吸光光度法和苯甲酸荧光分析法检测光/电Fenton降解orange II过程中H2O2和羟基自由基(.OH)的变化,表明orangeⅡ降解过程涉及.OH历程。 相似文献
135.
Luís Costa Kirsten Thonicke Benjamin Poulter Franz-W. Badeck 《Regional Environmental Change》2011,11(3):543-551
Within the changing fire regimes of Portugal, the relative importance of humans and climatic variability for regional fire
statistics remains poorly understood. This work investigates the statistical relationship between temporal dynamics of fire
events in Portugal and a set of socioeconomic, landscape, and climatic variables for the time periods of 1980–1990, 1991–2000,
and extreme fires years. For 10 of 15 districts, it was possible to observe moderate shifts in the significance of fire drivers
for the first two decadal periods. For others, pronounced changes of the significance of fire drivers were found across time.
Results point toward a dynamic (perhaps highly non-linear) behavior of socioeconomic and landscape fire drivers, especially
during the occurrence of extreme fire years of 2003 and 2005. At country level, population density alone explained 42% of
the inter-annual and inter-district deviance in number of fires. At the same temporal and spatial scale, the explanatory power
of temperature anomalies proved to explain 43% of area burnt. We highlight the necessity of including a broad set of socioeconomic
and landscape fire drivers in order to account for potential significance shifts. In addition, although climate does trigger
broad favorable fire conditions across Portugal mainland, socioeconomic and landscape factors proved to determine much of
the complex fire patterns at a subnational scale. 相似文献
136.
在给水曝气生物滤池内置粉末活性炭,对比分析其对各工艺单元水质净化效果的影响,确定给水曝气生物滤池内置粉末活性炭的作用与最佳投加量,研究表明,给水曝气生物滤池将活性炭截留在滤池内,大幅度提高了粉末活性炭利用率,部分未饱和粉末活性炭通过反冲洗排入后续常规处理系统,作为生物载体仍能够进一步发挥生物强化作用。当粉末活性炭的投加量为8 mg/L时,砂滤出水氨氮、CODMn、浊度和色度均值分别为:0.02 mg/L,1.82 mg/L0,.46 NTU和6度,去除率分别达到99.6%、71.2%、99.1%和80.6%,出水指标达到《生活饮用水卫生标准(》GB5749-2006)和《饮用净水水质标准(》CJ94-2005)规定的标准。与常规工艺相比,投加量降低了20%~60%。 相似文献
137.
138.
Cao ZJ Lu D Luo LS Deng YX Bian YG Zhang XQ Zhou MH 《Environmental science and pollution research international》2011,19(7):2690-2696
Purpose
Feathers are one of the most abundant bioresources. They are discarded as waste in most cases and could cause environmental pollution. On the other hand, keratin constituted by amino acids is the main component of feathers. In this article, we reported on biorefined feathers and integrants and application of degraded products.Materials and methods
The fermentation of whole chicken feathers with Stenotrophomonas maltophilia DHHJ in a scale-up of a 5-L bioreactor was investigated in this article. The fermentation process was controlled at 0.08 MPa pressure, 2.5 L/min airflow, and 300 rpm as 100% oxygen saturation level, 40°C, and pH 7.8.Results
Feathers were almost completely degraded in the tested fermentation reaction with the following conditions: 80 g of whole feathers in 3 L fermentation broth for 72 h, seed age of 16 h, 100 mL inoculation amount, and 50% oxygen saturation level. The degraded products contain 397.1 mg/L soluble protein that has mass weight ranging from 10 to 160 kD, 336.9 mg/L amino acids, and many kinds of metal ions. The fermentation broth was evaluated as leaf fertilizer and found to increase plant growth to 82% or 66% for two- or fourfold dilutions, respectively. In addition, in a hair care assay, the broth showed a hair protective function by increasing weight, flexibility, and strength of the treated hair.Conclusions
The whole feathers were degraded completely by S. maltophilia DHHJ. The degraded product includes many factors to life, such as peptides, amino acids, and mineral elements. It could be applied as leaf fertilizer and hair care product. 相似文献139.
Chen D Lu J Wang H Shen Y Gong D 《Environmental science and pollution research international》2011,18(8):1405-1413
Purpose
Nonpoint sources (NPS) pollution has been an important cause for water quality impairment worldwide. To take the temporal variations of both NPS pollution and in-stream attenuation into consideration, an inverse modeling approach and the load duration curve (LDC) method were combined for variable nutrient total maximum daily load (TMDL) development. 相似文献140.
Lu Q He ZL Graetz DA Stoffella PJ Yang X 《Environmental science and pollution research international》2011,18(6):978-986