Main particulate matter components in Saxony (Germany)

Aerosol filter samples have been collected nearby the industrialised basin of Leipzig in Saxony (Germany) at the research station Melpitz of the Institut für Troposphärenforschung e.V. (IfT). Time series (1992–1998) and a three year comparison (1995–1997) of two different aerosol filter sampling systems, the Sierra-Andersen-PM 10 high volume sampler (daily sample, PM 10 inlet) and the Rupprecht and Patashnik Co. Inc. Model Partisol 2000 (weekly sample, PM 10 and PM 2.5 inlet) are presented and discussed. The comparison of the different sampling systems and strategies yields small differences between the daily and weekly samples for mass and different ions, which may be influenced by sampling duration and flow rates. A general trend of change in aerosol composition was observed: Soot and Sulphate concentrations decreased whereas Nitrate and Ammonium concentrations increased. During summers the mass of coarse particles is higher than in other seasons. One reason could be found in the occurence of longer periods of dry ground surfaces enabling reemission of crustal and biological material. The time series have been integrated in a longer historical aerosol mass trend for Saxony and do show a good agreement. Since 1990 a significant downward trend in gravimetric mass concentration was found.     

基于激光雷达和超级站监测的一次沙尘过程分析

利用南京市气溶胶激光雷达网和草场门超级站监测数据,对2022年3月2—3日南京地区一次沙尘污染过程的垂直特征和地面PM_2.5组分变化进行了分析。结果表明,草场门、八卦洲和土桥3处点位的气溶胶激光雷达均观测到消光系数和退偏振比在凌晨至清晨时段有垂直分层现象,说明高空输入的沙尘气团位于城市污染气团上空,而此时地面PM_2.5组分以二次无机盐(硝酸盐、硫酸盐和铵盐)为主。中午前后,各高度的退偏振比及消光系数发生突变,主要是由高空输入沙尘和城市污染气团的垂直混合引起的。随着日间大气垂直交换的加大,PM_2.5中地壳物质的浓度均值和占比显著上升,其中浓度从3 μg/m³升高至5 μg/m³,占比从3%上升至10%。     

天津市PM2.5碳组分空间差异性及来源解析

2021年在天津市不同功能区共设置4个点位同步采集细颗粒物（PM_2.5）样品,测定了其中8种碳质亚组分的含量.结果表明,采样期间各点位ρ[有机碳（OC）]为3.7~4.4 μg·m^-3,ρ[元素碳（EC）]为1.6~1.7 μg·m^-3,OC浓度在中心城区最高,EC浓度差别较小.采用最小比值法对二次有机碳（SOC）进行估算,结果表明环城区二次污染较为突出,SOC占OC的比例达48.8%.各功能区碳质亚组分间的相关性强弱呈现出外围区>中心城区>环城区的特征,均表现出EC₁与OC₂和EC₁与OC₄相关性最强.正定矩阵因子（PMF）来源解析结果显示,道路扬尘源（9.7%~23.5%）、燃煤源（10.2%~13.3%）、柴油车尾气（12.6%~20.2%）和汽油车尾气（18.9%~38.8%）是天津市PM_2.5中碳组分的主要来源.不同功能区碳组分污染源存在差异,中心城区和外围区主要受汽油车尾气影响;环城区受二次污染和柴油车尾气的影响更为突出.     

天津市冬季颗粒物化学组成及其消光特征

于2013年冬季在天津大气边界层观测站利用Andersen撞击式采样器采集了26 d的颗粒物样品,并进行化学组分分析,同步观测颗粒物吸收系数、数浓度、能见度及其他气象要素. 对比分析了污染日和清洁日颗粒物质量浓度及其化学组成的粒径分布特征,在此基础上,利用Mie模型计算外混、内混、“核-壳” 3种混合态假设下颗粒物的消光系数、散射系数和吸收系数. 与实测吸收系数的比较可知,颗粒物的混合态可能更加接近“核-壳”态. “核-壳”态假设下颗粒物平均消光系数模拟值为(517.44±308.42)Mm-1,其中污染日平均值为(668.39±307.30)Mm-1,清洁日为(275.91±37.90)Mm-1,相对湿度对颗粒物的消光系数有显著影响. 污染日颗粒物中OM(有机质)、(NH₄)₂SO₄、NH₄NO₃、EC和其他物质对消光系数的贡献率分别为30.4%、25.5%、17.7%、8.1%和18.3%,清洁日分别为49.8%、11.0%、7.2%、10.6%和21.4%. PM_0.4~1.1、PM>1.1~2.1、PM>2.1~10的消光系数贡献率分别为69.6%±6.7%、13.9%±3.3%和16.5%±6.4%. 污染日高浓度的细粒子是导致能见度下降的主要原因,其中亚微米颗粒物对消光占据主导地位,(NH₄)₂SO₄、NH₄NO₃、OM是主要的消光化学组分.      

压力容器定期检验体积缺陷高度的简易检测

利用曝光曲线和胶片特性曲线,推导了焊缝内部体积缺陷高度的计算公式,缺陷高度计算公式适应于焊缝表面比较平滑的体积型缺陷计算。通过测量缺陷处底片黑度、缺陷附近焊缝处底片黑度、缺陷附近母材处底片黑度、缺陷附近焊缝高度,可以用公式计算焊缝内部体积缺陷高度,该公式能够应用于未焊透和条状夹渣的高度测定,并在压力容器定期检验时对未焊透和条状夹渣缺陷安全状况进行定级。     

民用燃料燃烧排放PM2.5和PM10中碳组分排放因子对比

在实验室中模拟民用燃料在家庭炉灶中的燃烧,应用稀释通道系统采集颗粒物,获得玉米秸秆、薪柴、蜂窝煤和块煤四种常用民用燃料燃烧排放PM10,PM2.5及载带碳组分的排放因子.结果表明,民用燃料燃烧排放的颗粒物以细颗粒为主, PM2.5占PM10的70%~90%.颗粒物排放因子最大的为块煤,其PM2.5和PM10的排放因子分别为9.837和11.929g/kg,分别是蜂窝煤的12.6和13.7倍;玉米秸秆和薪柴PM2.5和PM10的排放因子稍低于块煤,为7.359~10.444g/kg.4种燃料燃烧OC排放因子块煤最高,其在PM2.5和PM10中分别为5.29和5.19g/kg.薪柴燃烧EC的排放因子最高,其在PM2.5和PM10 中的排放因子分别为1.065和1.126g/kg.块煤两种粒径上EC的排放因子略低于薪柴.蜂窝煤EC的排放因子最低,比薪柴低300倍左右,玉米秸秆EC的排放因子也要比薪柴低10倍左右.碳组分是块煤,秸秆,薪柴排放颗粒物的主要成分,其含量在40%~60%之间,该值比蜂窝煤高3倍.四种燃料对应的OC/EC比值差异很大,薪柴和块煤燃烧排放颗粒该值为3~6,秸秆和蜂窝煤燃烧排放颗粒其值高达30~50.     

天津近岸海域大气颗粒物无机组分季节变化及源析

2006~2007年在天津近岸海域分4个季节走航采集了不同粒径大气颗粒物样品,分析了其质量浓度以及元素、离子和碳等化学组成,并应用富集因子以及特征化合物比值对其来源进行了探讨.结果表明,天津近岸海域TSP,PM10和PM2.5的质量浓度分别为(294.98±3.95),(279.87±17.53),(205.50±38.13)μg/m3,且呈现出明显的季节变化,秋季颗粒物浓度最高,冬季次之,夏季最低. TSP、PM10和PM2.5中总元素浓度分别为48.76, 47.94,32.08 μg/m3. TSP中含量最高的离子是Na+, PM10和PM2.5中含量最高的离子是Cl-. 3种不同粒径中OC浓度秋、冬两季均明显高于春夏两季. Al/Fe的比值分析结果表明,春季TSP的主要来源为土壤尘,秋、冬季PM10和PM2.5主要受燃煤的影响. Cu、Zn和Pb的富集系数较高,其中Pb在冬季PM10中富集达到最高为741.3. NO3-/SO42-的变化范围为0.28~0.85,春夏季该比值较高于秋冬季,反映了该海域同时受燃煤与机动车污染的影响.OC/EC变化范围为2.13~5.58,表明该海域气溶胶中存在着大量二次有机碳.     

Testicular DNA synthesis inhibition—an in vivo system for the detection of mutagenic and carcinogenic chemicals

By binding covalently to DNA chemical mutagens and carcinogens inhibit replication, which can be measured as a decrease in thymidine incorporation into DNA. This DNA synthesis inhibition (DSI) has been determined in testicular cells of mice for a large number of compounds and has been found to correlate very well with their known mutagenic and carcinogenic properties.

Not only could this test give a qualitative answer about potential carcinogenicity or mutagenicity, but, with regard to its in vivo characteristics, could furthermore give an indication of the carcinogenic and mutagenic potency and thus be of use in the risk evaluation of chemical substances; the relationship between the DNA synthesis inhibition and the underlying alkylation of guanine ‐0⁶ by different methylating agents is demonstrated.

As toxic effects decrease thymidine incorporation, too, means are discussed for distinguishing between “true”;, mutagenic, and “false”;, cytotoxic, DNA synthesis inhibition.

In conclusion, the implications of including the DSI‐test in a battery of mutagenicity tests are outlined.     

Determination of aflatoxin-B1 in poultry feed and its components employing enzyme-linked immunosorbent assay (ELISA)

A highly sensitive enzyme immunoassay was standardized for aflatoxin B₁ determination in poultry feed and its components using Riedel-de-Haen, ELISA Systems_. A microtitration plate method was optimized using anti-aflatoxin B₁ antibodies and peroxidase – aflatoxin B₁ conjugate, based on competitive enzyme immunoassay principle. Standards of concentrations of 5, 10, 20, 50, 100, 500?ng/L aflatoxin B₁, prepared in phosphate-buffered saline, were used. Standard curves showed that as the concentration of antigen decreased, absorbance values increased. Fifty percent inhibition was observed at 37?ng/L. Regression analysis showed that log concentration was inversely related to %B/B₀, with a highly significant negative correlation (?0.980). The lowest detection limit for aflatoxin B₁ was 5?ng/L. Using this standardized ELISA, aflatoxin B₁ was detected in most of the commercially available poultry feed samples and their components.

The data suggest that this test is suitable for the accurate determination of aflatoxin B₁ concentrations in poultry feed and its components.     

The spatial nexus between population growth and land degradation in a dry Mediterranean region: a rapidly changing pattern?

A better understanding of the spatial linkage between the distribution of land vulnerable to degradation and long-term population growth may contribute to sustainable land management of dry regions. Such a nexus has received increasing attention among politicians and local stakeholders, as its complex outcomes depend on mutual interactions between socioeconomic and biophysical factors. This is particularly true in southern Europe, where important processes of land degradation (LD) have been observed in recent years. This paper analyses population growth (1871–2007) in southern Italy and questions its relationship with the level of land vulnerable to degradation. Results indicate that vulnerable lands were more likely associated with areas where population growth has determined environmental pressures on coastal areas and the neighbouring lowlands during 1950–1980. This pattern consolidated the socioeconomic polarisation between core and peripheral areas. Since the 1980s, however, southern Italy has experienced a phase of polycentric development, possibly determining a ‘decoupling’ between population density and land vulnerability to degradation. Population increased in moderately vulnerable areas but decreased in highly vulnerable areas. The policy implications of these results are discussed.