校园室内外大气PM2.5中的含碳气溶胶及室内源特征

分夏、冬季采集南昌大学前湖校区室外和3个不同室内环境中的PM2.5,测定有机碳(OC)和元素碳(EC),并分析室内、外碳气溶胶质量浓度及其分布特征;利用OC-EC关系式半定量分析室内排放源;结合室内、外二次有机碳(SOC)和SOC/OC的分布进一步讨论不同室内排放源的特征及对SOC的影响;对4个采样点的8个碳组分丰度特征比较分析,结果表明复印/打印机对室内OC的贡献高,8个碳组分的丰度分布特征与其它排放源具有较明显的差异。     

二次有机气溶胶估算方法比较研究

为研究北京夏季二次有机气溶胶（SOA）浓度,比较多种SOA估算方法的不确定性和在我国的适用性,在CAREBEIJING 2008大型观测期间在城市点北大点和郊区点榆垡点采集大气颗粒物PM_2.5样品,利用多种方法对二次有机碳（SOC）的浓度进行了估算,估算方法包括二次有机示踪物产率法、非一次源OC法、非生物质燃烧水溶性有机碳法（WSOC）和元素碳示踪有机碳/元素碳比值法.估算结果表明,二次有机气溶胶已经成为北京颗粒有机物的重要组成部分,夏季SOC可以占总有机碳（OC）的50%甚至更高。通过模拟我国典型的生物质燃烧,实测建立适合我国的获得了非生物质燃烧WSOC方法中的重要参数,即获得方法中重要参数生物质燃烧排放颗粒物中WSOC/OC的比值,我国生物质燃烧颗粒物中该比值平均为0.48±0.04.多种方法结果均表明,SOA已经成为北京颗粒有机物的重要组成部分,所占比例可以达到50%甚至更高.利用化学质量守恒模型（CMB）和示踪物产率法对颗粒有机物来源进行闭合发现,依靠目前的示踪物技术北京大气颗粒有机物中仍然有20%～27%的来源不清楚.通过综合比较了多种SOC估算方法,确定了各方法在我国的适用性： 示踪物产率法、非一次源OC法和EC示踪OC/EC比值法可适用于我国大气中SOC的估算,但是非生物质燃烧WSOC方法仅适用于我国大气中水溶性SOC的估算,但是不同方法之间存在的系统误差.本研究还对这几种方法的不确定性做了初步的分析,为其他研究者选择估算方法提供参考和依据.示踪物产率法仅估算了几种特定VOCs前体物对SOC贡献,因此低估了总的SOC,但是这种方法是目前唯一一种可以估算特定VOCs前体物对SOC贡献的方法;同样地,非生物质燃烧WSOC法仅估算了水溶性的SOC,因此也低估了总的SOC;非一次源OC法高估了SOC,这主要是由于未能解析出的一次源OC造成的.而且这种高估在城市地区更为显著,主要是因为城市地区一次源相对比较复杂造成的;非生物质燃烧WSOC法低估了总的SOC,而且这种方法仅适用于我国水溶性SOC的估算;EC示踪OC/EC比值法的主要不确定性来自于一次源OC/EC比值的确定,由于这个比值造成的单点误差最高可高估54%或低估64%.     

深圳冬、夏季大气细粒子及其二次组分的污染特征

在2004年夏季和冬季, 分别在深圳宝安中心区进行了大气颗粒物细粒子的加强观测, 共获得30套样品. 通过对样品质量浓度、化学成分分析, 结合采样期间的气象条件, 对深圳当前大气颗粒物的污染特征、季节变化规律(夏季和冬季)及二次污染特征进行了研究. 结果表明, 深圳大气颗粒物污染的季节差异较大, 在夏季加强观测期间, PM_2.5和PM₁₀的日均质量浓度分别为34.9 μg·m^-3和56.9 μg·m^-3; 冬季加强观测期间PM_2.5和PM₁₀的日均质量浓度分别为99.0 μg·m^-3和134.8 μg·m^-3, 分别比夏季增长184%和137%. PM_2.5在夏季和冬季观测期间平均分别占PM₁₀的61%和73%, 细粒子污染严重; 夏、冬季加强观测期间OC和EC的比值平均分别为3.4和1.6, 估算的SOC占OC的比例平均分别为56%和6%, 夏季SOC对OC的贡献显著; 在夏季持续高温期间, 二次颗粒物的浓度及其在PM_2.5中的比重都急剧升高, 本地二次污染严重; 当夏季主导风向来自西南或东南海面时, 大气环境质量较好, 冬季主导风向来自北方内陆时, 大气环境质量较差.     

大气气溶胶中有机碳和元素碳监测方法的进展

本文主要介绍和评述了近10年来大气气溶胶中的有机碳和元素碳的采样和分析技术的进展,引用参考文献41篇。     

黄河口区有机碳同位素地球化学研究

本文对黄河下游河水中的颗粒有机碳(POC)及其同位素组成做了一个年度的测量,结合溶解态碳的文献资料,估算出黄河POC和总碳的年入海通量。通过对黄河口区三个航次118个站位295个水样和115个沉积物样品的400多个有机碳同位素数据的分析,结合水样中悬浮体含量、POC浓度和沉积物样的粒度参数、有机碳含量的资料,综合对比研究后提出了一个黄河细颗粒泥沙入海扩散的新模式。     

湿法氧化法测定水中总有机碳不确定度的评定

采用湿法氧化法对水中总有机碳的不确定度进行了评定.对测量重复性、标准偏差、标准溶液浓度等影响测量结果的不确定度分量进行分析和量化,当水中总有机碳测定结果为5.3 mg/L时,扩展不确定度为0.32 mg/L.     

有机碳材料在光电催化系统中的作用

有机碳材料因电荷传导效率高、结构可调、无污染等特点被广泛应用于光电催化领域。将含有机碳材料的催化剂作为电极材料已成为光电催化领域的研究热点之一。本文介绍了几种常见的有机碳材料的结构、特点、制备方法及其研究方向,并将含有机碳材料的电极进行分类。主要总结并论述了有机碳材料在光电催化系统中的五种作用:(1)作为催化剂;(2)作为光敏剂(3)作为电子介质;(4)作为催化剂载体;(5)作为光电极的稳定剂,最后阐述了有机碳材料在光电催化系统中的研究现状及难点问题。     

基于高分辨质谱在线观测的2011深圳大运会前后PM1化学组成与粒径分布

本文利用先进的高分辨飞行时间气溶胶质谱仪(HR-ToF-AMS)于2011年深圳世界大学生运动会前后(2011年8月3日~9月22日)对深圳市区大气亚微米细粒子(PM1)化学成分和粒径分布进行了在线测量.结果表明,整个观测期间PM1质量浓度平均为51.1±32.6gm3,其中有机物占颗粒物总质量的37.9%,硫酸盐为37.1%,铵盐11.9%,黑碳6.6%(由一台单颗粒黑碳光度计(SP2)单独测量),硝酸盐5.8%,氯化物0.6%.观测期间各成分(除黑碳外)的粒径分布峰值位于真空动力学粒径550nm附近,而有机物在较小粒径范围(100~200nm)仍有较多质量分布,显示出本地一次源的明显贡献.基于高分辨有机质谱计算得到的有机气溶胶的平均元素组成为:碳34.0%、氢53.2%、氧12.0%和氮0.8%(原子个数百分比),对应的OM/OC(有机物与有机碳质量比)平均值为1.66±0.16.采用正矩阵因子解析(PMF)模型对有机气溶胶高分辨质谱进行因子解析,得到三类有机气溶胶:HOA(还原态有机气溶胶),SV-OOA(半挥发氧化态有机气溶胶)和LV-OOA(低挥发氧化态有机气溶胶),分别占有机物总量的31.3%,39.8%和28.9%,说明二次有机气溶胶(以SV-OOA和LV-OOA之和代表)是有机气溶胶的主体部分.结合气团来源分析不同时段PM1化学组成和粒径分布特征表明,大运会召开期间PM1质量浓度水平比整个观测期间的平均值低60.7%,是气团来自洋面等有利气象条件和黄标车限行等污染源控制措施的综合作用结果.     

岩溶地下水中溶解性有机碳测定方法的探讨

总有机碳(TOC)是以碳的含量来表示环境水体中有机物总量的综合指标,是反映水体受污染程度的重要指标。溶解性有机碳(DOC)是总有机碳的一种,通常定义为通过一定孔径(0.22～0.7μm)的滤膜后,水质中所含有机碳的含量[1]。水体中DOC的存在形式主要有溶解态、胶体态和少量较小     

基于气溶胶质谱的二次有机气溶胶识别

二次有机气溶胶(SOA)是大气气溶胶十分重要的组成部分,也是目前人们认识最为薄弱的气溶胶组分.由于有机气溶胶化学组成的复杂性,对SOA进行有效的识别和估算一直是国际气溶胶研究领域的热点和难点问题.本研究尝试使用一种新方法来定量识别深圳冬季大气中的SOA:利用气溶胶质谱仪在线观测的高时间分辨率优势和质谱中的特征碎片离子,应用正定矩阵因子解析(PMF)模型对细粒子组分的主要来源进行解析,识别出其中的二次有机物.结果表明:深圳冬季大气细粒子中SOA浓度平均为9.41±6.33μg/m3,占总有机物质量的39.9±21.8%;相比于一次有机气溶胶(POA),SOA浓度水平变化较为平缓,体现了区域性二次污染物的特征.SOA/BC比值具有鲜明的日变化规律,且与Ox(O3+NO2)的日变化规律相似,说明SOA的生成过程显著地受控于大气光化学活性.深圳冬季大气SOA生成最活跃的时段约为9～15时,期间SOA/BC比值增长了122%.本文为研究我国大气二次有机气溶胶提供了一种新的技术方法和思路.     

Hyphenation of a carbon analyzer to photo-ionization mass spectrometry to unravel the organic composition of particulate matter on a molecular level

The carbonaceous fraction of airborne particulate matter (PM) is of increasing interest due to the adverse health effects they are linked to. Its analytical ascertainment on a molecular level is still challenging. Hence, analysis of carbonaceous fractions is often carried out by determining bulk parameters such as the overall content of organic compounds (OC) and elemental carbon (EC) as well as the total carbon content, TC (sum of OC and EC), however, no information about the individual substances or substance classes, of which the single fractions consist can be obtained. In this work, a carbon analyzer and a photo-ionization time-of-flight mass spectrometer (PI-TOF-MS) were hyphenated to investigate individual compounds especially from the OC fractions. The carbon analyzer enables the stepwise heating of particle samples and provides the bulk parameters. With the PI-TOF-MS, it is possible to detect the organic compounds released during the single-temperature steps due to soft ionization and fast detection of the molecular ions. The hyphenation was designed, built up, characterized by standard substances, and applied to several kinds of samples, such as ambient aerosol, gasoline, and diesel emission as well as wood combustion emission samples. The ambient filter sample showed a strong impact of wood combustion markers. This was revealed by comparison to the product pattern of the similar analysis of pure cellulose and lignin and the wood combustion PM. At higher temperatures (450 °C), a shift to smaller molecules occurred due to the thermal decomposition of larger structures of oligomeric or polymeric nature comparable to lignocelluloses and similar oxygenated humic-like substances. Finally, particulate matter from gasoline and diesel containing 10% biodiesel vehicle exhaust has been analyzed. Gasoline-derived PM exhibited large polycyclic aromatic hydrocarbons, whereas diesel PM showed a much higher total organic content. The detected pattern revealed a strong influence of the biodiesel content on the nature of the particulate organic material.     

Carbonaceous species of TSP in urban and rural sites around coal-fired power stations in northwestern Greece

Total suspended particles from urban and rural locations around an industrial complex with four coal-fired power stations were collected for a period of 6 months (January-June 2001). Mass concentrations of TSP and carbonaceous species (TC, EC, OC and BC) were determined for seven sampling sites of the studied area. The contribution of TC mass to the total particle mass was similar for all sites with an average value of 12.36±1.27%. The fraction of elemental carbon (EC) was estimated between 32 and 46% of the total carbon (TC). The relationship between organic and elemental carbon showed the primary origin of organic carbon (direct emissions). The OC/BC ratio values were also considered in order to get information about the enrichment of aerosols in organic carbon. Four conditional categories out of the sampling site ‘collection were additionally extracted (“urban”, “rural”, “far” and “close” location to the power stations) and considered with respect to the values of the ratios OC/BC and OC/EC and the multiple correlation coefficients R² for the concentrations of OC, BC and EC. It has been found that in some cases the correlation coefficients rather than the ratios could inform on the type of site.     

Rapid extraction of water soluble organic compounds from airborne particulate matter.

Water soluble organic compounds (WSOC) in airborne particulate matter (PM) have received considerable attention in recent years due to their abundance and their importance in atmospheric processes. The analysis of WSOC is necessary for quantifying the relative contribution of individual organic compounds to the total WSOC mass. In the present work, we evaluated the performance of a microwave-assisted extraction (MAE) method for the determination of WSOC in PM and compared the data with those of a conventional ultrasonic extraction (USE). The experimental results showed that the MAE method requires a shorter extraction time (5 min) compared to USE. The isolated water-soluble organic fraction of PM was subsequently analyzed using ion chromatography (IC) for low molecular weight organic acids. The rapid MAE method was used in conjunction with IC for the analysis of organic acids in PM samples, collected from different sources.     

~(13)C固体核磁共振技术检测PM_(2.5)中的总有机碳质组分

建立了13C固体核磁共振技术检测PM2.5中总有机碳质组分的分析方法。针对大气气溶胶中有机质组分的复杂性,探索出较为快速检测PM2.5中总有机质组分的核磁共振分析方法,使样品无需进行繁琐的前处理即可获得可靠的化学结构信息。利用该方法获得了太原、新乡、广州冬季PM2.5样品中总有机物的化学结构信息。结果表明,该方法操作简单,检测较为快速,准确度较高,可以满足大气气溶胶总有机成分的检测要求。     

Measurement of the carbonaceous component in the Milan urban particulate matter

The carbonaceous component in the Milan urban particulate matter, i.e. the two components black carbon (BC) and organic carbon (OC), has been measured by means of a thermogravimetric analyzer combined with an infrared spectrophotometer (TGA/FT-IR). While black carbon may be considered a primary pollutant, organic carbon includes both primary emissions and secondary organic aerosols. Since carbonaceous aerosol (including a small quantity of inorganic carbon, too) makes up roughly from 25% to 50% of the average annual PM 2.5 mass concentration, a deeper understanding of this component is required. The TGA/FT-IR technique, employed for the first time to our knowledge for the quantification of the particulate matter carbonaceous component, allows, thought the results here presented are preliminary, to assess the two components BC and OC in a simple way especially if compared with the methods reported in the literature. The total carbon (TC) determinations performed by TGA/FT-IR on Milan urban particulate matter are in good agreement with the results obtained by a total organic carbon (TOC) analyzer operating directly on the solid sample.     

Carbonaceous aerosol in the breathable particulate matter (PM10) in urban area

Carbonaceous material is a large fraction of urban aerosol and it is classified into Elemental Carbon (EC) and Organic Carbon (OC). EC particles are emitted from combustion sources. Because most combustion sources are anthropogenic and generally EC does not undergo chemical transformations, EC is a good indicator of primary anthropogenic primary pollution. OC particles species are emitted from primary emission sources either anthropogenic or biogenic sources. In this paper we have measured the ground concentration of Particulate Matter (PM), Total Carbon (TC), EC and OC in two Monitoring Stations in Rome. The first station is situated downtown Rome (near S.M. Maggiore Cathedral) where the traffic emission flux is strong. The second station is located in the inner a green park (Villa Ada Park): this site is not directly influenced by anthropogenic emissions. The results show that in Rome the TC contribution is about 30% of PM and the OC/EC vary between 0.5 and 1.5 according to the site we are considering. About the chemical particle composition the long-chain carboxylic have been identified as major constituent of organic aerosol and a range values are reported for two important compound class, the Polyciclic Aromatic Hydrocarbons and the nitro-PAHs wich are at very low levels.     

A novel single-run dual temperature combustion (SRDTC) method for the determination of organic, in-organic and total carbon in soil samples

The quantification of organic (OC) and inorganic carbon (IC) in soils provides an essential tool for understanding biogeochemical processes. Examples of its potential application are the assessment of the humification degree of soil organic matter, the calculation of carbon fluxes and budgets in terrestrial systems on a regional and global scale and the investigation of the carbon storage potential of soils. The verification of changes in carbon stocks requires an extensive number of samples as well as precise and reliable analyses.Due to the wide variation in the concentrations of the two forms of carbon in solid samples, the exact distinction is very difficult. We present the advantages of a single-run dual temperature combustion method (SRDTC) at 515 °C for OC and 925 °C for IC, which allows the determination of OC, IC and total carbon (TC) within one single analytical run. The three parameters are analyzed in less than 30 min. Additionally, the method is characterized by a significantly reduced variability and low operator bias, as there is no need of chemical sample pre-treatment. It is applicable to a broad range of varying OC and IC contents, which is demonstrated by the use of numerous synthetic soil mixtures that have been analyzed. Furthermore, SRDTC indicates the presence of thermally instable carbonates, like magnesite, in the sample. Use of silver boats as a catalytic agent results in an improved distinction between OC and IC in this case. To examine the accuracy and reliability of the SRDTC method, it was compared to other techniques frequently used for carbon determination in soil samples: total combustion by elemental analysis to determine TC and acidification of the sample prior to combustion to determine OC. We will show that the rugged SRDTC method offers a substantial progress for both the reliable and rapid OC and IC determination in soil samples where elemental carbon is negligible.