Missing OH reactivity in a forest: evidence for unknown reactive biogenic VOCs

Forest emissions of biogenic volatile organic compounds (BVOCs), such as isoprene and other terpenes, play a role in the production of tropospheric ozone and aerosols. In a northern Michigan forest, the direct measurement of total OH reactivity, which is the inverse of the OH lifetime, was significantly greater than expected. The difference between measured and expected OH reactivity, called the missing OH reactivity, increased with temperature, as did emission rates for terpenes and other BVOCs. These measurements are consistent with the hypothesis that unknown reactive BVOCs, perhaps terpenes, provide the missing OH reactivity.     

后G20时期杭州市挥发性有机物和可吸入颗粒物的特征分析

后G20时期（2016年9月至2017年12月）,臭氧成为杭州夏季首要大气污染物,可吸入颗粒物（PM₁₀）成为杭州冬季首要大气污染物。利用杭州市环境检测朝晖站和环境监测下沙站空气质量数据观测值分析55种挥发性有机化合物（VOC）的臭氧形成潜力,并使用美国国家环境保护局研发的第3代大气质量预估模型（WRF-CMAQ）对杭州市中心PM₁₀的污染数值进行模拟分析,提出了后G20时期PM₁₀和臭氧的最佳管控方案。结果显示:在后G20时期杭州市中心和城郊,芳香烃所占臭氧形成潜力比例最高,其次为烯烃和烷烃,最后为乙炔。在市区和城郊,乙烯、间/对二甲苯、甲苯、丙烯和乙苯依次为生成臭氧最主要的5种挥发性有机化合物,因此管控这5种挥发性有机化合物能最大程度的减少臭氧质量浓度。2017年杭州市中心春夏秋冬四季的PM₁₀中分别有50%,32%,48%和45%源于杭州市以外污染源的长距离跨地域传输。其中,春秋冬三季通过长距离传输来到杭州市区的PM₁₀主要源于市区的北方,夏季则主要源于市区的西南方。2017年,杭州市区的交通源、工业源、生活源与农业源对本地排放PM₁₀的贡献率分别为62.6%,27.8%,7.3%和2.3%。当杭州本地的工业源和交通源在2016年的基础上分别减排15%和5%时,杭州市中心的PM₁₀年均质量浓度可低于70 μg·m-3,达到二类区的标准。     

Urban leakage of liquefied petroleum gas and its impact on Mexico city air quality

Alkane hydrocarbons (propane, isobutane, and n-butane) from liquefied petroleum gas (LPG) are present in major quantities throughout Mexico City air because of leakage of the unburned gas from numerous urban sources. These hydrocarbons, together with olefinic minor LPG components, furnish substantial amounts of hydroxyl radical reactivity, a major precursor to formation of the ozone component of urban smog. The combined processes of unburned leakage and incomplete combustion of LPG play a significant role in causing the excessive ozone characteristic of Mexico City. Reductions in ozone levels should be possible through changes in LPG composition and lowered rates of leakage.     

Observations of ozone formation in power plant plumes and implications for ozone control strategies

Data taken in aircraft transects of emissions plumes from rural U.S. coal-fired power plants were used to confirm and quantify the nonlinear dependence of tropospheric ozone formation on plume NO(x) (NO plus NO(2)) concentration, which is determined by plant NO(x) emission rate and atmospheric dispersion. The ambient availability of reactive volatile organic compounds, principally biogenic isoprene, was also found to modulate ozone production rate and yield in these rural plumes. Differences of a factor of 2 or greater in plume ozone formation rates and yields as a function of NO(x) and volatile organic compound concentrations were consistently observed. These large differences suggest that consideration of power plant NO(x) emission rates and geographic locations in current and future U.S. ozone control strategies could substantially enhance the efficacy of NO(x) reductions from these sources.     

The Cometary and Interstellar Dust Analyzer at comet 81P/Wild 2

The CIDA (Cometary and Interstellar Dust Analyzer) instrument on the Stardust spacecraft is a time-of-flight mass spectrometer used to analyze ions formed when fast dust particles strike the instrument's target. In the spectra of 45 presumably interstellar particles, quinone derivates were identified as constituents in the organic component. The 29 spectra obtained during the flyby of Comet 81P/Wild 2 confirm the predominance of organic matter. In moving from interstellar to cometary dust, the organic material seems to lose most of its hydrogen and oxygen as water and carbon monoxide. These are now present in the comet as gas phases, whereas the dust is rich in nitrogen-containing species. No traces of amino acids were found. We detected sulfur ions in one spectrum, which suggests that sulfur species are important in cometary organics.     

Sighting of el chichon sulfur dioxide clouds with the nimbus 7 total ozone mapping spectrometer

The eruptions of El Chichón volcano on 28 March and 3 and 4 April 1982 were observed by the Nimbus 7 total ozone mapping spectrometer due to strong absorption by volcanic gases at the shortest wavelengths of the spectrometer (312.5 and 317.5 nanometers). These ultraviolet pictures permit a measurement of the volume, dispersion, and drift of volcanic gas clouds. The tropospheric clouds were rapidly dispersed in westerly winds while persistent stratospheric clouds drifted in easterly winds at speeds up to 13 meters per second. The spectral reflectance is consistent with sulfur dioxide absorption and rules out carbon disulfide as a major constituent. A preliminary estimate of the mass of sulfur dioxide deposited in the stratosphere by the large eruptions on 3 and 4 April is 3.3 x 10(6) tons. Prior estimates of volcanic cloud volume were based on extrapolation of locally measured sulfur dioxide concentrations.     

Ozone: depression of frond multiplication and floral production in duckweed

Plants of Lemna perpusilla #6746 grown in an environment charged daily with a low concentration of ozone over 2 weeks were slower to begin multiplying, had a significantly lower rate of frond doubling, and required longer to produce fewer flowers than control plants. Treated plants produced smaller, slightly yellow fronds but had no symptoms of acute injury. Control plants produced four times as many fronds and six times as many flowers as plants continuously exposed to ozone (0.1 part per million).     

Heterogeneous atmospheric aerosol production by acid-catalyzed particle-phase reactions

According to evidence from our laboratory, acidic surfaces on atmospheric aerosols lead to potentially multifold increases in secondary organic aerosol (SOA) mass. Experimental observations using a multichannel flow reactor, Teflon (polytetrafluoroethylene) film bag batch reactors, and outdoor Teflon-film smog chambers strongly confirm that inorganic acids, such as sulfuric acid, catalyze particle-phase heterogeneous reactions of atmospheric organic carbonyl species. The net result is a large increase in SOA mass and stabilized organic layers as particles age. If acid-catalyzed heterogeneous reactions of SOA products are included in current models, the predicted SOA formation will be much greater and could have a much larger impact on climate forcing effects than we now predict.     

Ambient levels of ozone reduce net photosynthesis in tree and crop species

Experiments were conducted to measure the photosynthetic response of three crop and four tree species to realistic concentrations of ozone and (for tree species only) simulated acidic rain. The ozone concentrations were representative of those found in clean ambient air, in mildly to moderately polluted air such as occurs in much of the United States during the summer, and in more heavily polluted air. However, the highest concentrations of ozone used were lower than those found regularly in the Los Angeles area. The mean pH of the simulated acid rain treatments ranged from more alkaline to much more acidic than the mean pH of precipitation in the United States. Exposure to any increase in ozone reduced net photosynthesis in all species tested. In contrast, acidic rain had no negative effect on photosynthesis in tree species, and no interaction between ozone and acidic rain was observed. Ozone-induced reductions in photosynthesis were related to declines in growth or yield. Species with higher stomatal conductances and thus higher potential for pollutant uptake exhibited greater negative responses to similar ozone treatments. Since exposure to ozone concentrations typical of levels of the pollutant observed in the eastern half of the United States reduced the rates of net photosynthesis of all species tested, reductions in net photosynthesis may be occurring over much of the eastern United States.     

O3与O3/H2O2两个体系降解除草剂2,4-D反应特性研究

分别采用O3、O3/H2O2体系降解苯氧羧酸类除草剂2,4-D,探讨了降解过程中反应温度、pH值、O3混合气流量、有机物初始浓度等操作条件的变化对降解动力学的影响。结果发现,温度和pH值的影响较大,O3流量影响最小,温度升高、pH值增大、臭氧流量增加、2,4-D初始浓度降低均有助于降解速率的提高。O3/H2O2体系中,H2O2能促进O3分解产生大量自由基,导致2,4-D反应活化能降低。和O3相比,O3/H2O2体系降解效果好,降解时间短,反应条件温和,操作费用低,是很有发展前景的高级氧化技术。     

有机农业投入品创新与丰产型有机农法创建

经过3年的试验发现,微生物肥可以完全替代化肥,形成基于有益微生物分解、拮抗功能的土壤生物肥力和生物抗病虫能力,取得正常产量,保障作物健康,提升产品品质;臭氧水可以替代许多化学农药,形成基于臭氧超强氧化功能的空气净化能力和防治病虫害能力,解决一些农作物病虫害问题。以有机农业为目标,将微生物肥和臭氧水技术融合配套,深入开展方案设计与技术创新,形成一些主要作物丰产型有机农法方案。     

近地层臭氧对农作物产量影响的风险评估模型研究进展

近地层臭氧污染及其对农作物产量和粮食安全的负面效应已成为国内外广泛关注的焦点之一,建立适宜且更为精确的模型开展臭氧影响下的农作物产量损失评估对于粮食安全保障及臭氧污染控制具有重要的意义。综述了浓度响应、剂量响应和通量响应等统计模型的发展及其在产量损失评估中的应用,评述了其优缺点和通量响应模型的不确定性,同时,通过臭氧干沉降模型的研究进展及其与通量响应模型的优势比较,提出了基于观测和臭氧干沉降模型开展臭氧影响下的自然农田作物产量损失评估技术新的研究方向。     

Nuclear decay techniques in ion chemistry

The spontaneous decay of chemically bound radioactive atoms affords a route to ions of well-defined structure and charge location, free of counterions. The nuclear nature of the ionization process makes it insensitive to environmental effects, so that exactly the same charged species can be generated, and its reactivity investigated, in widely varying media, from low-pressure gases to liquids and solids. Techniques based on nuclear decay are used in studies of the production of otherwise inaccessible species, the structural characterization of free ions, and the comparative evaluation of their reactivity in different environments, in particular, gas phase and solution.     

CLIMATE: A New Route Toward Limiting Climate Change?

Climate change mitigation strategies have focused on reductions in carbon dioxide and other long-lived greenhouse gases. Smith et al., investigate the viability of a different strategy, recently proposed by Hansen et al., which focuses on controlling short-lived pollutants such as soot and tropospheric ozone. They conclude that carbon dioxide must remain the primary focus of climate change mitigation strategies.     

2007年深圳市蔬菜农药残留情况分析

2007年1～12月选取深圳市6个区中的30家超市、28家农贸,在每个超市农贸中抽取10个蔬菜样品,共选取6 551份样品,然后采用农药快速检测方法结合气相色谱和气质联用法测定其中的24种农药残留。结果表明,2007年蔬菜农药检出率与超标率为5.31%和2.99%,分别比2006年下降1.93%和1.24%。说明2007年的蔬菜农药残留比2006年有明显下降;引起蔬菜农药超标的主要原因是有机磷农药残留,高毒农药的使用有所下降,菊酯类农药引起的超标情况有所上升,应有针对性的加强监督管理。     

An intelligent control chart for monitoring of autocorrelated egg production process data based on a synergistic control strategy

Monitoring livestock production processes by means of statistical control charts can provide an important support for management. The non-stationary and autocorrelated characteristics of most data originating from such processes impede the direct introduction of these data into control charts. To deal with these characteristics Engineering Process Control strategies can be applied. Stationarity was achieved by modelling and subtracting the time dependent trend using a non-linear model. Next, the autocorrelation structure in the residual data is modelled and corrected for by means of an ARMA model. The resulting corrected stationary and independent residuals are then inserted in the traditional cusum control scheme. This combined use of Engineering Process Control strategies for modelling the unconventional statistical characteristics and Statistical Process Control strategies for constructing the control chart based on the resulting pre-processed data, is referred to as a Synergistic Control strategy. The developed cusum control chart was tested on data of two layer flocks. In both cases the control chart provided alarms for important problems in production and furthermore signalled problems that remained unnoticed by the layer managers. The amount of false alarms was acceptable. With this control scheme and the scheme of the average egg weight, control procedures for two important output parameters of the production process of consumption eggs are available. Furthermore, this strategy could provide a possible solution for other process parameters that also display non-stationarity and autocorrelation.     

O3预氧化处理微污染黄河水源水研究

[目的]为净化微污染黄河水源水寻求一种较好的工艺。[方法]研究不同浓度O3投加量和反应时间对微污染黄河水源水中的主要污染物质如色度、CODMn、UV254、NO2-N和NH4＋-N的去除效果。[结果]色度明显下降,CODMn降低了10%,UV254下降了58.9%,NO2--N降低了42.69%,NH4＋-N略有增加。处理该微污染黄河水源水,最佳预氧化时间为2 min,臭氧投加量为2.7 mg/L。[结论]O3预氧化技术对黄河微污染水源水有良好的处理效果。     

春夏季温州雁荡山杉木林臭氧质量浓度垂直变化特征

森林中臭氧浓度不仅影响林木生长,也影响游憩环境质量,是森林康养环境研究的热点之一。根据2017年春夏两季对温州雁荡山国家森林公园内杉木Cunninghamia lanceolata林不同垂直高度臭氧浓度及气象因子昼夜24 h同步监测数据,分析了不同高度臭氧浓度的变化规律及其影响因素。结果表明:除春季H₃（林冠上层）臭氧质量浓度日最大8 h均值达到中国二类环境功能区质量要求外（≤200 μg·m-3）,两季节中其余各高度臭氧质量浓度日最大8 h均值及小时均值均达到中国一类环境功能区质量要求（≤160 μg·m-3）;春夏两季各高度臭氧质量浓度从小到大依次为H₁（距地面1.5 m）,H₂（林冠中部）和H₃,且春季H₁,H₂和H₃臭氧质量浓度日均值差值高于夏季;两季各高度臭氧质量浓度均为日间高、夜间低,且高值出现于11:00-15:00,低值出现于5:00;春夏两季各高度臭氧质量浓度小时均值与温度、风速呈正相关,与相对湿度呈负相关;春季各高度臭氧质量浓度与气压呈负相关。总体来讲,在雁荡山杉木林环境中,以臭氧质量浓度变化规律为游憩及游憩设施布设标准,在时间的选择上,夏季比春季更适合出游,且夜间优于白天;在空间的选择上,建议选择林下及树冠中部布置游憩设施,如林下栈道及空中栈道或森林木屋等设施。     

The role of biogenic hydrocarbons in urban photochemical smog: Atlanta as a case study

The effects of natural hydrocarbons must be considered in order to develop a reliable plan for reducing ozone in the urban atmosphere. Trees can emit significant quantities of hydrocarbons to metropolitan areas such as Atlanta, and model calculations indicate that these natural emissions can significantly affect urban ozone levels. By neglecting these compounds, previous investigators may have overestimated the effectiveness of an ozone abatement strategy based on reducing anthropogenic hydrocarbons.     

Selective bond dissociation and rearrangement with optimally tailored, strong-field laser pulses

We used strong-field laser pulses that were tailored with closed-loop optimal control to govern specified chemical dissociation and reactivity channels in a series of organic molecules. Selective cleavage and rearrangement of chemical bonds having dissociation energies up to approximately 100 kilocalories per mole (about 4 electron volts) are reported for polyatomic molecules, including (CH3)2CO (acetone), CH3COCF3 (trifluoroacetone), and C6H5COCH3 (acetophenone). Control over the formation of CH(3)CO from (CH3)2CO, CF3 (or CH3) from CH3COCF3, and C6H5CH3 (toluene) from C6H5COCH3 was observed with high selectivity. Strong-field control appears to have generic applicability for manipulating molecular reactivity because the tailored intense laser fields (about 10(13) watts per square centimeter) can dynamically Stark shift many excited states into resonance, and consequently, the method is not confined by resonant spectral restrictions found in the perturbative (weak-field) regime.