The macroeconomic determinants of volatility in precious metals markets

This paper models the monthly price volatilities of four precious metals (gold, silver, platinum and palladium prices) and investigates the macroeconomic determinants (business cycle, monetary environment and financial market sentiment) of these volatilities. Gold volatility is shown to be explained by monetary variables, but this is not true for silver. Overall, there is limited evidence that the same macroeconomic factors jointly influence the volatility processes of the four precious metal price series, although there is evidence of volatility feedback between the precious metals. These results are consistent with the view that precious metals are too distinct to be considered a single asset class, or represented by a single index. This finding is of importance for portfolio managers and investors.     

Study of lead phytoavailability for atmospheric industrial micronic and sub-micronic particles in relation with lead speciation

Particles from channelled emissions of a battery recycling facility were size-segregated and investigated to correlate their speciation and morphology with their transfer towards lettuce. Microculture experiments carried out with various calcareous soils spiked with micronic and sub-micronic particles (1650 ± 20 mg Pb kg⁻¹) highlighted a greater transfer in soils mixed with the finest particles. According to XRD and Raman spectroscopy results, the two fractions presented differences in the amount of minor lead compounds like carbonates, but their speciation was quite similar, in decreasing order of abundance: PbS, PbSO₄, PbSO₄·PbO, α-PbO and Pb⁰. Morphology investigations revealed that PM_2.5 (i.e. Particulate Matter 2.5 composed of particles suspended in air with aerodynamic diameters of 2.5 μm or less) contained many Pb nanoballs and nanocrystals which could influence lead availability. The soil-plant transfer of lead was mainly influenced by size and was very well estimated by 0.01 M CaCl₂ extraction.     

东北地区城市大气颗粒物中多环芳烃的污染特征

2008年4月至2009年1月期间,在东北三省(辽宁、吉林、黑龙江)设立30个观测点位,研究了东北城市大气颗粒物中PAHs的浓度水平、分布及来源.结果表明,不同季节14种PAHs总浓度的变化范围是16.3 ～712.1 ng/m3,呈冬季高、夏季低的季节变化特征；PAHs组成以4～5环化合物为主,3～4环化合物受温度的影响较大,表现出较强的季节波动；8个城市中抚顺和吉林PAHs污染最重,城市不同功能区中以工业区污染较重；燃煤和机动车尾气是区域PAHs的主要来源.     

Appraisal of measurement methods, chemical composition and sources of fine atmospheric particles over six different areas of Northern Belgium

Daily and seasonal variation in the total elemental, organic carbon (OC) and elemental carbon (EC) content and mass of PM_2.5 were studied at industrial, urban, suburban and agricultural/rural areas. Continuous (optical Dustscan, standard tapered element oscillating micro-balance (TEOM), TEOM with filter dynamics measurement system), semi-continuous (Partisol filter-sampling) and non-continuous (Dekati-impactor sampling and gravimetry) methods of PM_2.5 mass monitoring were critically evaluated. The average elemental fraction accounted for 2-6% of the PM_2.5 mass measured by gravimetry. Metals, like K, Mn, Fe, Cu, Zn and Pb were strongly inter-correlated, also frequently with non-metallic elements (P, S, Cl and/or Br) and EC/OC. A high OC/EC ratio (2-9) was generally observed. The total carbon content of PM_2.5 ranged between 3 and 77% (averages: 12-32%), peaking near industrial/heavy trafficked sites. Principal component analysis identified heavy oil burning, ferrous/non-ferrous industry and vehicular emissions as the main sources of metal pollution.     

青岛市区春夏季大气能见度与颗粒物的关系

利用青岛市灰霾综合观测站2012年3月2日-2012年6月7日期间的监测数据,分析了青岛市区大气能见度与不同粒径颗粒物质量浓度的日变化特征,比较了各级别大气能见度下不同粒径颗粒物质量浓度及所占比例的相关性,研究了相对湿度对大气能见度和颗粒物质量浓度相关性的影响.结果表明,监测时段大气能见度与颗粒物质量浓度呈现较好的负相关,每天大气能见度最低值出现在早晨07:00--09:00;剔除相对湿度高于90％的前提下,PM2.5是影响大气能见度的主要因子,随着其在PM1o中所占比例上升,大气能见度级别不断下降,相关系数为-0.84;不同相对湿度区间下,PM2.5对大气能见度的影响最明显,其中,相对湿度为60％ ～ 70％,大气能见度与颗粒物质量浓度之间的相关性最好.     

百色市右江区大气PM10中水溶性无机离子的化学特征与来源

2010年10月至2011年9月采集百色市右江区大气PM10样品,分析PM10及其水溶性无机离子的化学特征与来源。结果表明:(1)百色市右江区大气PM10为13.89～319.44μg/m3,年均117.48μg/m3,年均值超过《环境空气质量标准》(GB 3095-2012)二级标准(100μg/m3)。百色市右江区大气可吸入颗粒物的污染主要出现在春冬季节。(2)水溶性无机离子浓度年均值依次为SO24->NO3->Cl->NH4+>K+>Na+>Mg2+>F-,SO24-、NO3-和Cl-浓度最高,分别占水溶性无机离子的57.7%、14.9%和14.5%。(3)百色市右江区大气PM10呈较强的酸性,高浓度的SO42-可能是导致百色市右江区大气PM10呈较强酸性的主要原因。(4)PM10的季节变化受气温和风速的影响极显著;气象因素对SO42-、NO3-、F-的影响不显著。(5)主因子分析表明,PM10中水溶性无机离子可能来自3个方面,Cl-和NO3-主要来自于当地低烟卤煤燃烧排放的烟气;Mg2+、K+和Na+主要来自于自然源;F-、SO24-和NH4+主要来自于混合源。     

Gas/particle partitioning of atmospheric PCDD/Fs in a satellite town in Eastern China

Gas/particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in ambient air was investigated in a satellite town in Eastern China from April 2007 to January 2008 comprehending large temperature variations (from 3 to 34 °C, daily average). Molecular weight, molecular structure and ambient temperatures are the three major factors that govern the gas/particle partitioning of atmospheric PCDD/Fs throughout the year. Generally, good agreements were obtained (except for winter) between measured particulate fractions and theoretical estimates of both the Junge–Pankow adsorption model and Harner Bidleman absorption model using different sets of subcooled liquid vapor pressure and octanol–air partition coefficient (K_oa), respectively. Models utilizing estimates, derived from gas chromatographic retention indices (GC-RIs), are more accurate than that of entropy-based. Moreover, during winter, the K_oa-based model using the GC-RIs approach performs better on lower chlorinated PCDD/Fs than that of -based. Furthermore, possible sources of mismatch between measured and predicted values in winter (3–7 °C) were discussed. Gas adsorption artifact was demonstrated to be of minor importance for the phenomena observed. On the other hand, large deviations of slopes (m_r) and intercepts (b_r) in logK_p vs. plots from theoretical values are observed in the literature data and these are found to be linearly correlated with ambient temperatures (P<0.001) in this study. This indicates that the non-equilibrium partitioning of PCDD/Fs in winter may be significantly influenced by the colder temperatures that may have slowed down the exchange between gaseous and particulate fractions.     

东营春季PM10中有机碳和元素碳的污染特征及来源

2010年4月采集了东营市大气PM10样品,测定了PM10的浓度,并采用IMPROVE-TOR方法准确测量了样品中的8个碳组分.结果表明,采样期间,东营市大气PM10的平均浓度为(147.02±56.22) μg/m3；PM10中有机碳(0C)、元素碳(EC)浓度平均值分别为11.82、3.68 μg/m 3；PM10中OC和EC显著相关,表明OC、EC的来源相同；所有采样点PM10中OC/EC均大于2.15,表明存在二次有机碳(SOC)的贡献；PM10中SOC平均质量浓度是3.91 μg/m3,占OC质量浓度的33.08％；通过计算PM10中8个碳组分丰度,初步判断东营市颗粒物中碳的主要来源是汽车尾气、道路扬尘和燃煤.     

西安市及周边地区MODIS气溶胶光学厚度与PM10浓度关系模型研究

西安是空气污染监控和防治有代表性的西部大型城市。研究了西安市及周边地区上空气溶胶光学厚度与PM10浓度的关系模型。利用2011—2012年MODIS卫星气溶胶光学厚度（AOD）遥感产品，通过数据匹配，利用地面气象观测站点的能见度数据和相对湿度数据对AOD产品进行垂直标高订正和湿度订正，2项订正显著提高了AOD和地面PM10浓度的相关性，相关系数从0．36提高到0．65，按季节分类统计和订正春至冬四季的相关系数分别为0．57、0．71、0．62和0．87，夏季和冬季的订正更为有效，可用性更高，这可能由于受到不同季节气溶胶来源和特征的影响。为研究中国西部大型城市，特别是西安市空气环境监测和区域联防联控提供了一种有效方法。     

大中型商场PM10、PM2.5污染水平与来源分析

利用便携式气溶胶监测仪,对平顶山市区的中原商场、商业大楼、食品城总店三家大型商场不同楼层空气PM10和PM2.5进行了现场测定。结果显示,平顶山市大中型商场可吸入颗粒物污染严重,PM10、PM2.5污染平均超标率分别为13.7%和48.0%;PM10、PM2.5的质量浓度在时间和空间分布上存在很大差异;PM10中PM2.5所占比例为83%。