Inhalation health effects of fine particles from the co-combustion of coal and refuse derived fuel

This paper is concerned with health effects from the inhalation of particulate matter (PM) emitted from the combustion of coal, and from the co-combustion of refuse derived fuel (RDF) and pulverized coal mixtures, under both normal and low NO_x conditions. Specific issues focus on whether the addition of RDF to coal has an effect on PM toxicity, and whether the application of staged combustion (for low NO_x) may also be a factor in this regard.

Ash particles were sampled and collected from a pilot scale combustion unit and then re-suspended and diluted to concentrations of 1000 μg/m³. These particles were inhaled by mice, which were held in a nose-only exposure configuration. Exposure tests were for 1 h per day, and involved three sets (eight mice per set) of mice. These three sets were exposed over 8, 16, and 24 consecutive days, respectively. Pathological lung damage was measured in terms of increases in lung permeability.

Results show that the re-suspended coal/RDF ash appeared to cause very different effects on lung permeability than did coal ash alone. In addition, it was also shown that a “snapshot” of lung properties after a fixed number of daily 1-h exposures, can be misleading, since apparent repair mechanisms cause lung properties to change over a period of time. For the coal/RDF, the greatest lung damage (in terms of lung permeability increase) occurred at the short exposure period of 8 days, and thereafter appeared to be gradually repaired. Ash from staged (low NO_x) combustion of coal/RDF appeared to cause greater lung injury than that from unstaged (high NO_x) coal/RDF combustion, although the temporal behavior and (apparent) repair processes in each case were similar. In contrast to this, coal ash alone showed a slight decrease of lung permeability after 1 and 3 days, and this disappeared after 12 days. These observations are interpreted in the light of mechanisms proposed in the literature. The results all suggest that the composition of particles actually inhaled is important in determining lung injury. Particle size segregated leachability measurements showed that water soluble sulfur, zinc, and vanadium, but not iron, were present in the coal/RDF ash particles, which caused lung permeabilities to increase. However, the differences in health effects between unstaged and staged coal/RDF combustion could not be attributed to variations in pH values of the leachate.     

Effects of trichloroacetic acid on the nitrogen metabolism of Pinus sylvestris--a 13C/15N tracer study

Trichloroacetic acid (TCA) can be found in various environmental compartments like air, rain and plants all over the world. It is assumed that TCA is an atmospheric degradation product of volatile chloroorganic hydrocarbons. The herbicide effect of TCA in higher concentrations is well known, but not much is known about the phytotoxic effects in environmentally relevant concentrations. It can be shown in this study by using the 13C/15N stable isotope tracer technique that [13C]TCA is taken up by roots of two-year-old seedlings of Pinus sylvestris L. and transported into the needles. At the same time the effect of the substance on nitrogen metabolism can be analyzed by measuring the incorporation of 15NO3- into different nitrogen fractions of the plant. The more [13C]TCA incorporation, the higher the synthesis of 15N labelled amino acids and proteins is. These effects on the nitrogen metabolism are probably based on the activation of stress- and detoxification metabolism. It has to be assumed that there is an influence on N metabolism of Pinus sylvestris caused by the deposition of environmentally relevant TCA concentrations.     

Improved vacuum-UV (VUV)-initiated photomineralization of organic compounds in water with a xenon excimer flow-through photoreactor (Xe2* lamp, 172 nm) containing an axially centered ceramic oxygenator

Xenon excimer (Xe2*) lamps can be used for the oxidation and mineralization of organic compounds in aqueous solution. This vacuum-ultraviolet (VUV) photochemical method is mainly based on the photochemically initiated homolysis of water that produces hydrogen atoms and hydroxyl radicals. The efficiency of substrate oxidation and mineralization is limited markedly due to the high absorbance of water at the emission maximum of the Xe2* lamp (lambda(max)=172 nm). This photochemical condition generates an extreme heterogeneity between the irradiated volume V(irr) and the non-irradiated ("dark") bulk solution. During VUV-initiated photomineralization of organic substrates, the fast scavenging of hydrogen atoms and of carbon-centered radicals by dissolved molecular oxygen produces a permanent oxygen deficit within V(irr) and adjacent compartments. Hence, at a constant photon flux the concentration of dissolved molecular oxygen within the zones of photo and thermal radical reactions limits the rate of mineralization, i.e. the rate of TOC diminution. Thus, a simple and convenient technique is presented that overcomes this limitation by injection of molecular oxygen (or air) into the irradiated volume by use of a ceramic oxygenator (aerator). The tube oxygenator was centered axially within the xenon excimer flow-through lamp. Consequently, the oxygen or air bubbles enhanced the transfer of dissolved molecular oxygen into the VUV-irradiated volume leading to an increased rate of mineralization of organic model compounds, e.g. 1-heptanol, benzoic acid and potassium hydrogen phthalate.     

Postgraduale Weiterbildung, Nachwuchsf?rderpreis 2005, Jahrestagung 2006 in Landau

Ohne Zusammenfassung     

Chemisch-analytische Untersuchung von Arsenkampfstoffen und ihren Metaboliten

Zusammenfassung  Arsenkampfstoffe sind in der Umwelt persistent und kontaminieren bis heute Boden und Grundwasser. In diesem Beitrag werden die chemischen Reaktionen der Arsenkamptstoffe Diphenylarsinchlorid (CLARK I), Phenylarsindichlorid (PFIFFIKUS), Ethylarsindichlorid (DICK) sowie von Chlorvinylarsinverbindungen (LEWISITE) dargestellt. Die M?glichkeiten der chemisch-analytischen Erfassung dieser chemischen Kampfstoffe als Originalsubstanzen und als Thiol-Derivate werden pr?sentiert.      

Effects of ethanol addition on micellar solubilization and plume migration during surfactant enhanced recovery of tetrachloroethene

Alcohol addition has been suggested for use in combination with surfactant flushing to enhance solubilization kinetics and permit density control of dense non-aqueous phase liquid (DNAPL)-laden surfactant plumes. This study examined the effects of adding ethanol (EtOH) to a 4% Tween 80 (polyoxyethylene (20) sorbitan monooleate) solution used to flush tetrachloroethene (PCE)-contaminated porous media. The influence of EtOH concentration, subsurface layering and scale on flushing solution delivery and PCE recovery was investigated through a combination of experimental and mathematical modeling studies. Results of batch experiments demonstrated that the addition of 2.5%, 5% and 10% (wt.) EtOH incrementally increased the PCE solubilization capacity and viscosity of the surfactant solution, while reducing solution density from 1.002 to 0.986 g/cm3. Effluent concentration data obtained from one-dimensional (1-D) column experiments were used to characterize rate-limited micellar solubilization of residual PCE, which was strongly dependent upon flow velocity and weakly dependent upon EtOH concentration. Two-dimensional (2-D) box studies illustrated that minor differences (0.008 g/cm3) between flushing and resident solution density can strongly influence surfactant front propagation. A two-dimensional multiphase simulator, MISER, was used to model the influence of EtOH composition on the aqueous flow field and PCE mass recovery. The ability of the numerical simulator to predict effluent concentrations and front propagation was demonstrated for both 1-D columns and 2-D boxes flushed with EtOH-amended Tween 80 solutions. Results of this study quantify the potential influence of alcohol addition on surfactant solution properties and solubilization capacity, and demonstrate the importance of considering small density variations in remedial design.     

Photodynamic action of some sensitizers by photooxidation of luminol

We report the development of a novel simple experimental method which allows the comparison of new photosensitizers based on their production of reactive oxygen species. A high-performance liquid chromatography (HPLC) assay permits the monitoring of several substances (sensitizer, reactant and oxidized end product) simultaneously on a single chromatogram. Photoreactions were monitored throughout their course by the HPLC assay surveying the sensitizers' efficiency of singlet oxygen production by the oxidative decomposition of luminol. Several photosensitizers were tested: Rose Bengal, Methylene Blue, Protoporphyrin IX, Photosan III, Photofrin, Hypericin and Pseudohypericin. Additionally, photoreactions were monitored by a standard pO₂ detection system. The measurements of the two detection methods were strongly correlated. Rose Bengal proved to be the most efficient photosensitizer, clearly decreasing the luminol concentration and causing a corresponding increase in aminophthalic acid. Our experiments show that when factors necessary for photochemical reactions are absent or are blocked (antioxidants), no reaction can be detected.     

罗斯比中心区域气候模型Ⅱ:北极圈气候的应用

作为ARCMIP国际计划的一部分,罗斯比中心区域气候模型(RCA2)针对整个北冰洋地区的气候作了数值模拟整合,并与来自sHEBA数据集的观测资料作了比较,RCA2标准模型对北极冬季的云量和长波辐射的模拟较实况偏多.通过引入新的云量参数化方案(该参数化方案显著地改进了云量的年循环)减少了这部分误差,确定了介于晴空向下大气长波辐射与云层底部的长波辐射的补偿率,利用可以更准确描述冰晶与太阳辐射相互作用的辐射方案修正了模型,从而使得模型对云-太阳辐射间的相互作用的描述更接近实际.在模拟晴空辐射部分,由于太阳辐射大气透射率过大,经常在边界层云的顶部产生正偏差.引入真实海冰和积雪两种表面反照率的时间变化,对准确模拟地面能量净收支是至关重要的.同样,为了准确模拟北极圈地区近地面的热力学过程,将雪面温度作为预报量引入模型中也似乎是必不可少的.