中国东部典型森林生态系统蒸散及其组分变异规律研究

森林蒸散包括植被蒸腾、土壤蒸发、冠层截留蒸发三个组分,在陆地生态系统水分循环及能量流动研究中占有重要地位。论文基于Priestley-Taylor Jet Propulsion Laboratory Model （PT-JPL）模型,估算温带针阔混交林、人工常绿针叶林、亚热带常绿阔叶林三个典型森林生态系统2003-2008年蒸散（组分）;在模拟结果基础上揭示了蒸散（组分）的季节变异规律及主控因子。结果表明：①PT-JPL模型在中国东部森林生态系统蒸散及其组分估算中具有较高的稳定性和可靠性;②蒸散（组分）季节变化特征明显,不同森林生态系统类型变化规律差异较小,但主控因子存在较大差异：温带针阔混交林蒸散和植被蒸腾季节变异主要由净辐射和增强植被指数（EVI）共同控制,而亚热带人工常绿针叶林和亚热带常绿阔叶林主要受净辐射影响;EVI和饱和水汽压差（VPD）是土壤蒸发季节变异的主控因子,截留蒸发的季节变化则主要受VPD影响。     

密闭压力容器小型循环试验结果

在联合国危险品运输试验和标准建议书(桔皮书)中,系列E涉及评价物质在密闭容器中对剧烈加热的热爆炸敏感性的标准。但是人们一直希望并致力于发展一种定量,可靠,重复性好的方法来评价物质的热爆炸敏感性。本文介绍了一种小型密闭压力容器循环试验的研究及其作为一种筛选试验向联合国提案的最新进展。实验结果表明,几种物质在不同实验室的重复性非常好,其(dP／dt)max平均偏差率在20％以内,表明该小型密闭压力容器作为评价物质热反应危险性的测试方法具有较高的可靠性。     

Why are Californians interested in hybrid cars?

This paper explores quantitatively Californians' interest in hybrid electric vehicles (HEV) based on a statewide phone survey conducted in July 2004 by the Public Policy Institute of California. The paper develops ordered choice models and factors that summarise beliefs about energy and the environment using principal component analysis. As expected, Californians concerned about the environment, energy efficiency, global warming and recent increases in the price of gasoline state a higher interest in hybrids; an even more important reason for considering hybrid electric vehicles, however, is the possibility of using high occupancy vehicle (HOV) lanes while driving alone, especially for people with potentially long commutes to work. The findings also suggest that beliefs about energy and the environment should be included in vehicle type choice models.     

Molecular characterization of root exudates using Fourier transform ion cyclotron resonance mass spectrometry

The release of root exudates (REs) provides an important source of soil organic carbon. This work revealed the molecular composition of REs of different plant species including alfalfa (Medicago sativa L.), bean (Phaseolus vulgaris L.), barley (Hordeum vulgare L.), maize (Zea mays), wheat (Triticum aestivum L.), ryegrass (Lolium perenne L.) and pumpkin (Cucurbita maxima) using electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The combination of positive ion mode (+ESI) and negative ion mode (-ESI) increased the number of the molecules detected by ESI FT-ICR MS, and a total of 8758 molecules were identified across all the samples. In detail, lipids and proteins and unsaturated hydrocarbons were more easily detected in +ESI mode, while aromatic compounds with high O/C were readily ionized in -ESI mode, and only 38% of the total assigned formulas were shared by -ESI and +ESI modes. Multivariate statistical analysis of the formulas indicated that the close related plants species secreted REs with similar molecular components. Moreover, the unsaturation degree and nitrogen content were the two key parameters able to distinguish the similarities and differences of molecular components of REs between plant species. The results provided a feasible analysis method for characterization of the molecular components of REs and for the first time characterized the molecular components of REs of a variety of plant species using ESI FT-ICR MS.     

城市轨道交通系统组元脆弱性评价研究

为有效降低城市轨道交通系统的脆弱性,在脆弱性理论的基础上,界定城市轨道交通系统组元脆弱性的概念与内涵,并将其影响因素划分为人员、设备与环境3个指标组。整合DEMATEL、ANP与模糊VIKOR这3种系统分析评价方法,构建集成DEMATEL-ANP-FVIKOR方法的城市轨道交通系统组元脆弱性评价模型,并通过对北京地铁典型车站的评价来验证该评价模型的有效性。研究结果表明,该评价模型切实可行,能够对城市轨道交通系统组元脆弱性进行有效量化评价分析。     

京津冀典型城市一次重污染过程特征及边界层结构变化对其影响

为探究典型重污染过程的污染特征与大气边界层结构演变规律,基于PM_2.5采样数据、气象观测数据及WRF-Chem模式,以北京市和石家庄市2016年12月27日—2017年1月10日一次重污染过程为研究对象,对气象要素、PM_2.5化学组分、天气背景场、边界层结构演变特征,以及大气边界层结构变化对ρ(PM_2.5)及其主要化学组分的影响进行分析.结果表明:①研究期间,北京市和石家庄市ρ(PM_2.5)分别为(165.63±110.89)(247.67±95.22)μg/m3,石家庄市污染程度高于北京市;高空纬向环流和地面弱高压控制的天气背景场,低于1.75 m/s的风速以及超过75%的相对湿度是造成北京市与石家庄市重污染的不利气象条件.②重污染时段北京市与石家庄市SNA(SO₄2-、NO₃-、NH₄+三者的统称)与碳质组分(OC、EC)占比之和超过76%,是PM_2.5中的两大主要组分;重污染时段ρ(SNA)占比明显上升,北京市与石家庄市ρ(SNA)占比由非重污染时段的42.23%、45.93%分别升至重污染时段的58.87%、59.62%;北京市与石家庄市ρ(OC)/ρ(EC)分别为5.13、3.51,表明在重污染时段两城市存在明显的二次有机气溶胶污染.③WRF-Chem模式模拟结果表明,PM_2.5污染严重时北京市与石家庄市在300~500 m处均出现明显的逆温,垂直风场主要表现为低层偏南风顺时针向上切变为偏西风,切变高度在400~1 000 m,逆温层结与明显垂直风切变的边界层特征共同抑制了污染物的湍流与扩散.④北京市与石家庄市重污染时段的PBLH(Planetary Boundary Layer Height,大气边界层高度)日均值与非重污染时段相比分别下降了202、128 m,PBLH每下降100 m,北京市与石家庄市ρ(PM_2.5)分别上升18.81、29.85 μg/m3,PBLH下降是导致两城市ρ(PM_2.5)快速上升的重要因素.北京市与石家庄市的PBLH与PM_2.5组分质量浓度之间的相关性不同,北京市PBLH与ρ(SNA)的相关性高于与碳质组分质量浓度的相关性,石家庄市PBLH与ρ(EC)相关性最高,表明此次重污染过程中北京市PM_2.5污染特征以二次形成为主,而石家庄市以一次排放为主.研究显示,北京市与石家庄市此次重污染过程与大气边界层结构变化密切相关.      

典型钢铁企业挥发性有机物排放量测算及组分特征

选取涵盖钢铁炼制全流程的典型企业,综合采用不同核算方法估算比较了该企业挥发性有机物（VOCs）排放结果;并在此基础之上,通过氟聚化合物气袋、SUMMA罐采样及气相色谱质谱联用仪（GC-FID/MS）分析方法,对烧结、焦化、热轧和冷轧等工序废气中VOCs浓度水平及排放特征进行监测.结果表明,整个厂区VOCs年排放量为430.82t,其中工艺有组织排放占66.0%,储罐18.5%;烧结机头和焦炉推焦排放口VOCs及非甲烷总烃（NMHC）浓度高于其他点位;各工序排放的芳香烃占比较高,其中焦化装煤除尘和焦炉推焦排放口芳香烃占90%以上;烧结工序CS₂占比最高（36.6%）,其次为苯和甲苯;焦化工序占比靠前的物种为1,2,4-三甲基苯、邻甲乙苯、1,4-二乙基苯、1,2,3-三甲基苯和1,3,5-三甲基苯等;热轧工序与其他工序有一定区别,车间无组织排放芳香烃和烷烃占比均在35%左右,排放靠前的物种除芳香烃外还有高碳烷烃,如十一烷、十二烷和正丁烷等;冷轧工序有组织和无组织排放主要物种较为类似,均为芳香烃物种,如乙基苯、间/对二甲苯、甲苯、苯和邻二甲苯.不同工艺环节排放物种存在一定差异,但主要以焦化副产物（芳香烃）和烧结燃烧产物（CS₂）为主,建议钢铁行业有针对性地加强浓度高、活性高和毒性大的组分控制.     

Chemical characterization of size-resolved aerosols in four seasons and hazy days in the megacity Beijing of China

Size-resolved aerosol samples were collected by MOUDI in four seasons in 2007 in Beijing. The PM10 and PM1.8mass concentrations were 166.0 ± 120.5 and 91.6 ± 69.7 μg/m~3, respectively,throughout the measurement, with seasonal variation: nearly two times higher in autumn than in summer and spring. Serious fine particle pollution occurred in winter with the PM1.8/PM10 ratio of 0.63, which was higher than other seasons. The size distribution of PM showed obvious seasonal and diurnal variation, with a smaller fine mode peak in spring and in the daytime. OM(organic matter = 1.6 × OC(organic carbon)) and SIA(secondary inorganic aerosol) were major components of fine particles, while OM, SIA and Ca_2+were major components in coarse particles. Moreover, secondary components, mainly SOA(secondary organic aerosol) and SIA,accounted for 46%–96% of each size bin in fine particles, which meant that secondary pollution existed all year. Sulfates and nitrates, primarily in the form of(NH_4)_2SO_4, NH_4NO_3, Ca SO_4, Na_2SO_4 and K_2SO_4, calculated by the model ISORROPIA II, were major components of the solid phase in fine particles. The PM concentration and size distribution were similar in the four seasons on non-haze days, while large differences occurred on haze days, which indicated seasonal variation of PM concentration and size distribution were dominated by haze days. The SIA concentrations and fractions of nearly all size bins were higher on haze days than on non-haze days, which was attributed to heterogeneous aqueous reactions on haze days in the four seasons.     

Chemical formation and source apportionment of PM2.5 at an urban site at the southern foot of the Taihang mountains

The region along the Taihang Mountains in the North China Plain (NCP) is characterized by serious fine particle pollution. To clarify the formation mechanism and controlling factors, an observational study was conducted to investigate the physical and chemical properties of the fine particulate matter in Jiaozuo city, China. Mass concentrations of the water-soluble ions (WSIs) in PM_2.5 and gaseous pollutant precursors were measured on an hourly basis from December 1, 2017, to February 27, 2018. The positive matrix factorization (PMF) method and the FLEXible PARTicle (FLEXPART) model were employed to identify the sources of PM_2.5. The results showed that the average mass concentration of PM_2.5 was 111 μg/m³ during the observation period. Among the major WSIs, sulfate, nitrate, and ammonium (SNA) constituted 62% of the total PM_2.5 mass, and NO₃^? ranked the highest with an average contribution of 24.6%. NH₄⁺ was abundant in most cases in Jiaozuo. According to chemical balance analysis, SO₄^2?, NO₃^?, and Cl^? might be present in the form of (NH₄)₂SO₄, NH₄NO₃, NH₄Cl, and KCl. The liquid-phase oxidation of SO₂ and NO₂ was severe during the haze period. The relative humidity and pH were the key factors influencing SO₄^2- formation. We found that NO₃^? mainly stemmed from homogeneous gas-phase reactions in the daytime and originated from the hydrolysis of N₂O₅ in the nighttime, which was inconsistent with previous studies. The PMF model identified five sources of PM_2.5: secondary origin (37.8%), vehicular emissions (34.7%), biomass burning (11.5%), coal combustion (9.4%), and crustal dust (6.6%).     

硝酸浸提拆解废印制电路板元器件技术

研究了废印制电路板在不同浓度硝酸溶液中焊锡完全溶解的时间,以及Sn,Pb,Zn,Fe和Cu的溶解规律及循环利用浸提液的可行性. 结果表明:废印制电路板最佳剥离硝酸浓度为2 mol/L左右,该条件下210 min内废印制电路板上的焊锡完全溶解,元器件能够全部拆除;稀硝酸作为浸提液,可重复利用4次以上,各次循环对焊锡均具有较好的溶解效果;循环利用过程中,Cu反应速率逐次增加,易造成Cu的流失.