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2.
《Chemosphere》1987,16(6):1143-1147
γ-Lactones with 6 – 15 carbons have been detected for the first time in atmospheric aerosols. Their concentrations ranged from 0.07 ng/m3 to 0.7 ng/m3. 相似文献
3.
《Atmospheric environment (Oxford, England : 1994)》1999,33(22):3579-3595
Measurements of C2–C5 hydrocarbons on an hourly basis at the TNO site in Delft from 1982 to 1984 and at Moerdijk over the period 1981–1991 are presented. In combination with meteorological data (wind direction and wind speed) the Delft and Moerdijk series are evaluated to identify source categories, annual variations, background concentrations and trends. The C2–C5 hydrocarbon concentrations at Delft and Moerdijk are determined mainly by emission characteristics and meteorological dispersion; the dominant sources are relatively nearby and atmospheric degradation is not of much importance. Under conditions of high wind speed the concentrations measured at Moerdijk in the marine sector are close to the Atlantic background concentrations in winter and somewhat above this in summer. The continental background concentrations are higher than the marine background concentrations by a factor of almost two. The annual variation of acetylene is more pronounced than that of the other hydrocarbons, most likely due to a different seasonal variation in acetylene emissions. The annual variation of propene is smoother, indicating stronger sources in summer than in winter. This feature of propene is observed in continental as well as in marine sectors. The observations show that at Moerdijk C2–C4 concentrations measured in Rijnmond sector have decreased considerably since the early 1980s, corresponding with changes in emissions in that area. Averaged over all wind directions the trend of all species is downward, but for acetylene the trend is significant at a 95% confidence interval. The acetylene concentrations show an annual downward trend of 3% during the 1980s, supporting other estimates of decreasing hydrocarbon emissions from traffic over this period at the same rate. 相似文献
4.
《Atmospheric environment (Oxford, England : 1994)》2002,36(30):4839-4847
Most foods from plant origin usually contain 1–10 mg/kg (dry weight) of non-resolved isomeric alkanes in the range of the n-alkanes C20–C50 which are assumed to be residues from mineral oil products (in addition to the natural paraffins). In edible vegetable oils, concentrations may exceed 100 mg/kg. Since it was suspected that this contamination was mostly of environmental origin, particulate matter from air was analysed for the same range of paraffins. In a road tunnel, around 5 μg/m3 of such paraffins were found, corresponding to about 3% of the fine dust (PM10). The composition corresponded to that found in the particulate matter from the exhaust of diesel engines, which in turn largely corresponded to engine (lubricating) oil. In Swiss cities, the C20–C50 mineral paraffins in the PM10 from ambient air amounted to 0.1–1.5 μg/m3 (about 1% of the dust) and seemed to primarily originate from incomplete combustion of heating and diesel oil, lubricating oil, and road tar debris. On the countryside, the concentrations were around 0.03 μg/m3 (0.3% of the dust). Soil contained 0.5–10 mg/kg of these paraffins. The similarity of the molecular weight (volatility) distribution suggests that the food contamination with paraffins, is mostly from the air. A substantial proportion probably consists of lubricating oil. If this hypothesis is confirmed, measures should be investigated to reduce this contamination. 相似文献
5.
Shinji Saito Ippei Nagao Hiroshi Kanzawa 《Atmospheric environment (Oxford, England : 1994)》2009,43(29):4384-4395
To understand the characteristics of non-methane hydrocarbon (NMHC) abundance in an urban air of Nagoya, one of the metropolitan areas of Japan, 48 species of C2–C11 NMHCs were measured with a measurement system, developed in this study, by using gas chromatography with flame ionization detection (GC/FID) continuously for one year from December 2003 to November 2004.Annual mean concentration of NMHCs in normal and propylene equivalent (PE) in Nagoya was compared with those in four urban areas of Seoul, London, Lille, and Dallas to extract characteristics of urban air. While the absolute values of the normal and PE concentrations of alkanes, alkenes, alkyne, and aromatics were significantly different among these urban areas, the proportions of each chemical group to the total NMHC were not so different.In Nagoya, the total normal concentration was high from November to February and low from June to August. The pattern of the seasonal variation was influenced mainly by that of alkanes. On the other hand, the total PE concentration was high from July to December and low from January to June. The pattern of the seasonal variation was influenced mainly by those of alkenes and aromatics. Particularly the normal concentration of isoprene was high from May to September because of large emission associated with activity of plants. As the results, in summer, the PE concentration of isoprene was especially high, and its contribution to the total NMHCs measured in this study was approximately 40%. The total PE concentrations were high in summer when the concentration of OH radicals is also high, suggesting that the productions of ozone and secondary organic aerosol (SOA) are likely to be promoted in summer of Nagoya. 相似文献
6.
Emma L. Yates Richard G. Derwent Peter G. Simmonds Brian R. Greally Simon O’Doherty Dudley E. Shallcross 《Atmospheric environment (Oxford, England : 1994)》2010,44(23):2705-2713
Continuous in-situ measurements of NMHCs at Mace Head, Ireland during two full annual cycles from January 2005 to January 2007 were used to investigate NMHC emission sources and transport including dilution and photochemical oxidation. The Mace Head research station is ideally located to sample a wide range of air masses including polluted European transport, clean North Atlantic and Arctic air masses and the ultra-clean, Southern Atlantic air masses. The variety in air mass sampling is used to investigate interaction of emissions, transport, dilution and photochemistry. Variability of long-lived hydrocarbon ratios is used to assess and estimate typical transport times from emission source to the Mace Head receptor. Seasonality in the ratios of isomeric alkane pairs (for butane and pentanes) are used to assess the effects of atmospheric transport and photochemical ageing. Finally, the natural logarithms of NMHC ratios are used to assess photochemical oxidation. 相似文献
7.
《Atmospheric environment(England)》1985,19(11):1899-1904
Ambient air concentrations of specific C2–C6 hydrocarbons (HCs) are reported for various days during the summer months of 1983. The samples are classified as either urban, rural or polluted rural according to the sampling site, meteorological conditions and ozone levels. Generally, both the concentrations and HC/acetylene ratios are similar to those reported by other workers for comparable sites. The alkane/alkene ratio at the rural site exceeded that for the urban site and it is concluded that the major contribution to HCs at the former site is advection from distant sources. It appears that the main source of propane in rural areas is natural gas, with about 4.5–9 ppbC unaccounted for by this source. 相似文献
8.
《Atmospheric environment (Oxford, England : 1994)》2002,36(13):2157-2163
The equilibrium partitioning of formaldehyde (HCHO) between air and snow was studied in a series of laboratory experiments conducted at −5°C, −15°C, and −35°C, in order to understand how partitioning of HCHO between air and polar snow varies with temperature, and thus seasonally on the ice sheet. Measured partitioning coefficients were 56, 93, and 245 mol l−1 atm−1 for −5°C, −15°C and −35°C, respectively, showing a similar trend as the values previously estimated from field observations. Estimates of the pseudo-first-order rate coefficient for air–snow exchange for the same three temperatures were 4.1×10−4, 1.1×10−4, and 1.1×10−5 s−1, respectively. This implies a time scale for air–snow equilibration of the order of hours to days for HCHO accumulated at or near the ice–air interface on snow grains. Comparing the current laboratory partitioning coefficients with those estimated from measurements of air and freshly fallen snow in Greenland during summer demonstrates that the snow is supersaturated and should degas HCHO to the surrounding air. During this degassing, polar snow should be a significant source of HCHO to the lower troposphere. 相似文献
9.
Abstract The metabolism of 14C‐carbaryl and 14C‐1‐naphthol in moist and flooded soils was studied in a continuous flow‐through system over a period of 28 days permitting 14C‐mass balance. The percent distribution of radiocarbon in organic volatiles, carbon dioxide, extractable and non‐extractable (bound) fractions of soils were determined. Organic volatiles could not be detected in both carbaryl and 1‐naphthol treated soils. More of 14CO2 (25.6%) was evolved from moist than flooded soil (15.1%) treated with carbaryl. However, the mineralization of 14C‐1‐naphthol was negligible. The extractable radiocarbon was more in flooded soil (28.9%) than moist soil (5.5%) from carbaryl treatment. Less than one percent was present as parent compound, whereas carbaryl was mainly metabolized to 5‐hydroxy carbaryl in moist soil and to 4‐ and 5‐hydroxy carbaryl in flooded soil. The extractable radiocarbon amounted to 18.2 and 24.3% in moist and flooded soils respectively and the parent compound was less than one percent with 1‐naphthol treatment. Most of the radiocarbon was found as soil bound residues; the formation being more with 1‐naphthol than carbaryl. Humin fraction of the soil organic matter contributed most to soil bound residues of both carbaryl and 1‐naphthol. 相似文献
10.
为了新飞机试飞前能获得飞机边线噪声级,缩短新飞机噪声合格审定周期,对飞机边线有效感觉噪声级预测方法进行了研究,利用飞机相关物理参数及声压公式建立了完整的飞机边界噪声级预测算法。以波音、空客、CRJ系列飞机为例,验证该算法的有效性。控制飞机单一物理参数变化,分析各参数对飞机边线有效感觉边界噪声值的影响等级,提出降低飞机边线有效感觉噪声值的建议。将该算法应用于预测C919飞机边线噪声值,阐明了该算法在飞机噪声适航审定工作中的重要作用。 相似文献
11.
针对沈阳某药厂维生素C生产工艺中凝结水产量大、处理成本高和杂质复杂等问题,提出了采用反渗透技术对工艺凝结水进行处理。在前期确定的最优操作条件基础上持续运行,研究了运行临界通量、清洗时机和清洗方式等工艺条件。结果表明,在本工艺条件下,反渗透膜系统的临界通量介于1.1 L/(m2.min)到1.2 L/(m2.min)之间,斜率变点分析法确定的可逆膜污染周期为10 d;加强型清洗策略EFM(enhanced flux maintenance)的操作是针对不可逆膜污染的一种有效清洗方式,EFM持续30 min为宜,NaClO和NaOH都是有机污染的有效清洗剂,膜的平均恢复率分别为85.4%和81.6%,显示出实际应用的可行性,具有推广价值。 相似文献
12.
采用化学还原与电沉积方法制备了钯和石墨烯复合膜碳纸(Pd/rGO/C)电极。以制备的Pd/rGO/C电极为阴极,通过电化学还原法处理水中硝酸盐。结果表明,与碳纸(C)、石墨烯修饰碳纸(rGO/C)、钯修饰碳纸(Pd/C)电极相比,Pd/rGO/C电极对于硝酸盐还原具有更高的电催化活性及N2选择性。Pd和rGO具有良好的协同催化还原硝酸盐作用。当外加电压由-0.75 V降至-1.0 V时,Pd/rGO/C电极还原速率k值由0.001 min-1快速提高至0.061 min-1。中性条件更利于Pd/rGO/C电极还原硝酸盐及N2生成。同时,Pd/rGO/C电极对浓度区间为6.8~22.6 mg (NO3--N)/L硝酸盐催化还原效率较高,且反应液中未检测到金属Pd,无二次污染。 相似文献
13.
《Atmospheric environment(England)》1988,22(2):395-401
Atmospheric C2–C5 hydrocarbons were determined at Deonar, an industrial suburb north of Bombay, India, during 1985. Samples were pre-concentrated on silica gel at −78°C and subsequently desorbed on to a gaschromatographic column for separation and flame ionization detection. The seasonal pattern of the monthly geometric mean hydrocarbon concentrations are used to show that refinery emissions in addition to auto exhaust are a major source of hydrocarbons at Deonar. 相似文献
14.
针对维生素C生产工艺中产生的凝结水产量大、处理成本高、存储运输困难和营养物质含量偏低等问题,采用反渗透技术对VC凝结水进行处理。实验建立小试规模反渗透膜处理装置,采用无量纲化多元回归分析方法,分析了操作条件指标与渗透水评价指标两套指标体系之间的关系,定量评价了各个操作条件指标对渗透水评价指标的整体影响程度,并在此基础上研究了最佳操作条件的工艺参数。结果表明:建立的无量纲化多元回归分析方法切实有效,在正交实验设计水平范围内,压力、pH和回流比均是多目标系统的影响因子,操作条件指标对渗透水评价指标的整体影响程度大小顺序为:压力〉pH〉回流比〉温度,且各自影响程度所占比例分别为43.02%、29.01%、25.07%和2.89%。各个操作因子对多指标系统的影响是独立的。在只考虑系统收益而不考虑膜污染的情况下,最佳操作条件分别为:温度r=30.65,压力P=1.5MPa,回流比r=0.78,pH=7.475。 相似文献
15.
S.M.A.D. Zayed I.Y. Mostafa A.E. El‐Arab 《Journal of environmental science and health. Part. B》2013,48(1):169-175
Abstract 14C‐p,p'‐DDT‐bound residues in soil can be released by treatment with concentrated sulphuric acid at ambient temperatures. Within 6 days, about 70% of the bound residues was released. Bound residues released after 9 months incubation with 14C‐DDT showed the presence of DDT and DDE only while bound residues released after 18 months, contained in addition 13% DDD. Release of bound 14C‐residues also occurs readily following inoculation of the soil‐bound residues with fresh soil or with individual microorganisms. Almost complete release of bound residues was observed after incubation for 45 days. The rate of release was rapid during the first two weeks and decreased thereafter. TLC and HPLC analysis showed that the released residues contained DDE (about 80%) and a smaller amount of DDD. The disappearance of DDT from the released residues may be attributed to its microbiological degradation to DDE and DDD, shortly after its release. 相似文献
16.
《Atmospheric environment (Oxford, England : 1994)》2002,36(3):571-581
OH formation from the ozonolysis reactions of seven internal alkenes with 4–6 carbons, styrene, trans-β-methyl styrene, and α-methyl styrene was studied using complementary techniques. A small-ratio relative-rate technique in which small quantities of OH tracers are added to monitor OH formation yields provided the following results: trans-2-butene, 0.64±0.12; cis-2-butene, 0.33±0.05; trans-2-pentene, 0.46±0.08; cis-2-pentene, 0.29±0.06; trans-3-hexene, 0.53±0.08; cis-3-hexene, 0.36±0.07; and 2-methyl-2-butene, 0.98±0.24. For styrene, trans-β-methyl styrene, and α-methyl styrene, OH yields of 0.07±0.04, 0.22±0.09, and 0.23±0.12 were measured, respectively. A second method, which monitors product formation from the OH reaction with 2-butanol was used to derive OH formation yields from 2,3-dimethyl-2-butene, 2-methyl-2-butene and cis-2-pentene, and provided yields of 0.91±0.14, 0.80±0.12, and 0.27±0.07, respectively. The results are briefly discussed in terms of the relationship between structures of these alkenes and OH formation. 相似文献
17.
紫外线 (UV) 是一种高效、绿色的消毒技术,广泛应用于气、水和物体表面的病原微生物灭活。远C波段UV (远UV-C,200~230 nm) 消毒所需剂量辐照对人体的伤害尚未被发现,表明远UV-C具备人机共存原位消毒的潜力,因此该技术近期受到关注。概述了远UV-C光源、灭活机制和辐照安全性方面的研究进展:输出主峰位和半峰宽分别为222 nm和4 nm的KrCl准分子灯是最为成熟的消毒用远UV-C光源;远UV-C通过蛋白质损伤和核酸干扰2种途径实现病原微生物灭活,灭活能力较传统UV-C (如254 nm) 更强;尚未发现消毒所需剂量的远UV-C辐照导致的健康危害,如红斑和角膜炎。而在实际应用中,应谨慎对待高剂量远UV-C辐照暴露,确保在现有实验证据基础上,逐步提高远UV-C安全使用的剂量阈值,并考虑与通风系统或臭氧淬灭系统协同使用以避免伴生臭氧造成的二次伤害。本文旨在为远UV-C在高效灭活病原微生物、阻断高传染性疾病传播领域的应用提供参考。 相似文献
18.
为分析京津冀地区经济发展、环境负荷的发展状况及其与循环经济发展C模式目标值的符合度,将京津冀2005—2015年经济增长与环境负荷的变化同C模式目标值进行比较,结果表明,在经济水平超预期发展的前提下,能源消费和二氧化碳排放的增速均超过了目标值。预测发现,延续现有发展模式,能源消费总量与2050年的绝对脱钩目标存在3.5亿t(以标准煤计)的差距,二氧化碳排放量与绝对脱钩目标存在2.6亿t的差距。为实现脱钩,建议京津冀地区采取综合措施,完善产业结构并协同提升产业技术水平,提高能效,降低能源强度。同时,大力发展可再生能源替代不可再生能源,使2050年可再生能源消费占比达到60.0%。 相似文献
19.
The ability of thermal activated peroxydisulfate (PS) of mineralizing phenol at 70 °C from contaminated waters is investigated. Phenol in concentrations of 10−4 to 5 × 10−4 M is quantitatively depleted by 5 × 10−3 to 10−2 M activated PS in 15 min of reaction. However, mineralization of the organic carbon is not observed. Instead, an insoluble phenol polymer-type product is formed. A reaction mechanism including the formation of phenoxyl radicals and validated by computer simulations is proposed. High molecular weight phenolic products are formed by phenoxyl radical H-abstraction reactions. This is not the case for the room temperature degradation of phenol by sulfate radicals where sulfate addition to the aromatic ring mainly leads to the generation of hydroxycyclohexadienyl radicals leading to hydroxybenzenes and oxidized open chain products. Therefore, a change in the reaction mechanism is observed with increasing temperature, and thermal activation of PS at 70 °C does not lead to the mineralization of phenol. Thus PS activation at 70 °C may be considered a potential method to reduce the load of phenol in polluted waters by polymerization. 相似文献
20.
C1O2治理医院污水性能参数的研究 总被引:2,自引:2,他引:2
研究了C1O2作为消毒剂在去除医院污水中总大肠菌群数(CFU)时的性能参数。实验结果表明,C1O2加入量为5—8mg/L、温度为20—30℃、接触时间为30—60min、pH为7.8—8.5、填科为组合型,是C1O2去除CFU的最优参数,可使污水中CFU降至500个/L,达到国家一级排放标准(GB8978—1996)。同时,分析了各参数对CFU去除率的影响。 相似文献