温州市PM_(2.5)中水溶性离子污染特征及来源分析

2015年1~12月在温州市区采集448个PM_(2.5)样品,采用离子色谱法分析PM_(2.5)中9种水溶性离子(SO_4~(2-)、NO_3~-、NH_4~+、Cl~-、Na~+、K~+、Ca~(2+)、Mg~(2+)和F~-)的浓度,研究其污染特征、化学组分和来源.采样期间9种水溶性离子总浓度为39.97μg·m~(-3),SO_4~(2-)、NO_3~-和NH_4~+占所测水溶性离子总量的(40.19±10.04)%.离子总浓度的季节变化特征为冬季春季秋季夏季,从空间分布上看,多数季节市站采样点PM_(2.5)中离子总浓度低于南浦、龙湾和瓯海采样点.相关性分析结果显示,PM_(2.5)值与NH_4~+、Ca~(2+)、Na~+、K~+、Cl~-、NO_3~-、SO_4~(2-)浓度显著相关,PM_(2.5)中SO_4~(2-)和NH_4~+的主要结合方式为(NH_4)_2SO_4.硫氧化速率(SOR)和氮氧化速率(NOR)的年均值分别为0.44±0.09和0.13±0.04,表明温州市PM_(2.5)中SO_4~(2-)和NO_3~-主要由二次转化形成.主成分分析结果表明,温州市PM_(2.5)中水溶性离子主要来源于燃煤(火力发电和工业燃煤)、生物质燃烧、机动车尾气以及道路和建筑扬尘.     

秸秆燃烧排放PM2.5特征及影响因素研究

生物质燃烧向大气中排放大量颗粒污染物, 在中国, 收获季节大量秸秆被直接露天燃烧处理, 对区域环境质量和人体健康造成严重影响. 对我国最主要的两种粮食作物玉米和小麦秸秆的露天燃烧进行模拟, 分析颗粒物排放水平, 特征及影响因素. 玉米和小麦秸秆燃烧PM_2.5排放因子分别为1082.8和835.7~897.3 mg/kg. 有机物是颗粒物最主要组分, 总量占PM_2.5质量的42%~66%. Cl^-和K⁺分别占PM_2.5总质量的4%~15%和2%~14%, K⁺/EC值为0.5~3.8. 各物种在颗粒物中所占比例与之前研究结果一致. 秸秆含水量和燃烧温度影响PM_2.5排放水平和组成特征. 随秸秆含水量增加, PM_2.5和OC的排放因子增加; 秸秆含水量增加, 燃烧温度逐渐降低, 由生物质燃料释放进入烟气中的K⁺和Cl^-比例逐渐减小导致二者在颗粒物中的比例降低. 我国每年由玉米和小麦秸秆露天燃烧排放的PM_2.5和OC分别为92.7 Gg和47.5 Gg, 在总量中占重要比例.     

Effect of water vapour on particulate matter emission during oxyfuel combustion of char and in situ volatiles generated from rapid pyrolysis of chromated-copper-arsenate-treated wood

This paper reports the effect of water vapour on particulate matter (PM) during the separate combustion of in situ volatiles and char generated from chromated-copper-arsenate-treated (CCAT) wood at 1300 °C. Combustion of in situ volatiles produces only PM with aerodynamic diameter?<1?µm (i.e., PM₁), dominantly PM with aerodynamic diameter?<0.1?µm (i.e., PM_0.1). Water vapour could significantly enhance the nucleation, coagulation and condensation of fine particles and reduce the capture of Na and K by the alumina reactor tube via reduced formation of alkali aluminates, leading to increases in both yield and modal diameter of PM_0.1. Water vapour could also enhance char fragmentation hence increase the yield of PM with aerodynamic diameter between 1 and 10?µm (i.e., PM_1–10) during char combustion. For trace elements, during in situ volatiles combustion, volatile elements (As, Cr, Ni, Cu and Pb) are only presented in PM₁ and water vapour alters the particle size distributions (PSDs) but has little effect on the yields of these trace elements. During char combustion, As, Cr, Cu and Ni are present in both PM₁ and PM_1–10 while the non-volatile Mn and Ti are only present in PM_1–10. Increasing water vapour content increases the yields of As, Cr, Cu, Ni, Mn and Ti in PM_1-10 due to enhanced char fragmentation. During char combustion, water vapour also originates less oxidising conditions locally for enhancing As release, promotes the generation of gaseous chromium oxyhydroxides and inhabits the production of NiCl₂ (g), leading to increased yields of As and Cr and decreased yield of Ni in PM_0.1.     

PM2.5 in an industrial district of Zhengzhou,China:Chemical composition and source apportionment

Zhengzhou is a developing city in China,that is heavily polluted by high levels of particulate matter.In this study.fine particulate matter(PM_2.5) was collected and analyzed for their chemical composition（soluble ions,elements,elemental carbon（EC） and organic carbon（OC）） in an industrial district of Zhengzhou in 2010.The average concentrations of PM_2.5 were 181,122,186 and 211μg/m³ for spring,summer, autumn and winter,respectively,with an annual average of 175μg/m³,far exceeding the PM_2.5 regulation of USA National Air Quality Standards（15μg/m³）.The dominant components of PM_2.5 in Zhengzhou were secondary ions（sulphate and nitrate） and carbon fractions.Soluble ions,total carbon and elements contributed 41%,13%and 3%of PM_2.5 mass,respectively.Soil dust,secondary aerosol and coal combustion, each contributing about 26%,24%and 23%of total PM_2.5 mass,were the major sources of PM_2.5,according to the result of positive matrix factorization analysis.A mixed source of biomass burning,oil combustion and incineration contributed 13%of PM_2.5.Fine particulate matter arising from vehicles and industry contributed about 10%and 4%of PM_2.5,respectively.     

Source Apportionment of Ambient PM10 in the Urban Area of Longyan City,China: a Comparative Study Based on Chemical Mass Balance Model and Factor Analysis Method

In order to identify the day and night pollution sources of PM10 in ambient air in Longyan City,the authors analyzed the elemental composition of respirable particulate matters in the day and night amb...     

用于正电子断层扫描成像的68Ga标记PM2.5模拟粒子的制备及其活体示踪

将黑色素纳米颗粒(melanin nanoparticle,MNP)经聚乙二醇(polyethylene glycol,PEG)修饰制备得到PEG-MNP,随后通过与放射性的⁶⁸Ga³⁺离子螯合,高标记产率地制备得到⁶⁸Ga-PEG-MNP,标记产物稳定性良好。进一步将⁶⁸Ga-PEG-MNP通过雾化方式制备得到⁶⁸Ga-PEG-MNP PM_2.5(particulate matter 2.5,size<2.5 μm)模拟颗粒,其经雾化小鼠吸入体内后,通过正电子断层扫描(positron emission tomography,PET)成像对小鼠进行全身显影,结果可见雾化的⁶⁸Ga-PEG-MNP PM_2.5模拟颗粒可由气管向肺部双叶区域扩散,并滞留于肺。体内的PET成像结果与离体放射自显影结果高度一致。     

Anchoring of sulfur‐containing alkylphosphonic and semifluorinated alkylphosphonic molecules on a polycrystalline aluminum substrate

Self‐assembly on a polycrystalline aluminum substrate of two sulfur‐containing alkylphosphonic acids, CH₃? (CH₂)₁₁? S? (CH₂)₂? PO(OH)₂, and CF₃? (CF₂)₇? (CH₂)₂? S? (CH₂)₂? PO(OH)₂, has been compared with CH₃? (CH₂)₁₅? PO(OH)₂. The reaction of the phosphonic head groups with the hydroxyls at the alumina surface to form phosphonates was studied with X‐ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection‐absorption spectroscopy (PM‐IRRAS). Barrier effects of the resulting layers was assessed by electrochemical polarization curves. With the conditions used in the present work for the self‐assembly reaction, it appears that the sulfur‐containing molecules do not perform as well as CH₃? (CH₂)₁₅? PO(OH)₂ in terms of film quality. Questions are raised about the possibility that the sulfur‐containing molecules could undergo cleavage during surface modification. Copyright © 2008 John Wiley & Sons, Ltd.     

Probing PM2.5 with terahertz wave

The goal of continuous ambient participate monitoring has been accomplished by the use of terahertz(THz)wave.The frequency-dependent spectrum and absorbance of the particulate matter(PM2.5)were measured in the range of 0–10 THz.The PM2.5 concentration was calculated according to the sampling time and air flow.With the increase of,the THz wave amplitude gradually decreased and the absorbance A of PM2.5 increased.The relationship between and A can be described mathematically through A0.5.Our results demonstrate that the terahertz wave could be a valuable tool to monitor and inspect the PM2.5 concentration.     

Spectroscopic and PM5 semiempirical studies of new hydrazone of gossypol with 3,6-dioxaheptylhydrazine

A new hydrazone of gossypol with 3,6-dioxaheptylhydrazine (GHDO) has been synthesised and its structure has been studied by FT-IR, ¹H NMR, ¹³C NMR as well as PM5 semiempirical methods. All the studies have provided clear evidence of the existence of GHDO in the solution in the N-imine–N-imine tautomeric form. The structure and the spectroscopic behaviour of this tautomer are discussed in details. It is shown the structure of GHDO is strongly stabilised by different types of intramolecular hydrogen bonds. In two of them the oxygen atoms of the oxaalkyl chains are also engaged. The strongest intramolecular hydrogen bond is formed between the O₇H proton and N₁₆ atom from the hydrazone group.     

Spectroscopic and quantum chemical study on electronic and geometric properties of free and embedded dithizone molecules

The molecular and electronic structure of the three tautomeric forms of dithizone has been calculated by using semiempirical, density functional theory (DFT), and ab initio methods. Comparison of ground‐state energies shows the symmetric form most stabilized, but there is only a small barrier (<3 kcal/mol) for the hydrogen transfer from N? H toward H? S (enol form). For understanding the origin of the optical transitions intermolecular interactions have to be taken into account. By using the supermolecule method, the absorption band pattern can be rationalized already on the level of the PM3 model. The nuclear magnetic resonance (NMR) solution spectrum is interpreted in terms of an equilibrium between the symmetric and the enol forms of dithizone. The appearance of strong EPR signals only for the solid state reflects a considerable lowering of the triplet state (symmetric form). Experimental features are discussed in view of calculated energies (stabilization), chemical shifts (NMR), and SOMO orbitals (EPR). © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001