Ozone Episode in the Milan Metropolitan Area A Comparative Evaluation of UAM-V and CALGRID Models

Data from an ozone episode (2–5 June, 1998) in the Milan metropolitan area were used for an application of two photochemical grid models: UAM-V and CALGRID. To assure a fair comparison, the models were run on the same domain and grid size, with same source emission inputs, CALMET diagnostic meteorology, and initial and boundary conditions taken from air quality data and literature values. Hourly emissions were derived from the AutoOil-II programme inventory except for on-road mobile source emissions; a new traffic emission inventory, based on both COPERT II methodology and road classification has been developed. NO_x and O₃ concentration results were compared to local network monitoring data. Results indicate that both models predict the highest ozone values along the north-east direction and are able to reproduce the ozone daytime trend though differences can be found between the two models on ozone spatial distribution. Average normalised bias for both models is about 50%, peak daily ozone concentrations are underestimated, with simulated peak shapes broader than the observed ones and a temporal shift between the two models. Night-time concentration levels of pollutants were not successfully reproduced due to an incorrect parameterisation of vertical turbulence calling for further work.     

Adapting the Speciation of the VOCs Emission Inventory in the Greater Athens Area

An adaptation procedure of a new emission inventory of theGreater Athens Area is attempted, based on a sensitivityanalysis on the treatment of the VOC emissions. Throughthis procedure the impact that a more detailed treatment ofthe VOCs emissions might have on the atmospheric chemistrysimulations, is examined. For this analysis three differentchemical mechanisms were applied for two differentlocations (urban and city plume) with different VOC andNO_x mixture characteristics. Finally, this studyrecommends new carbon fractions, reflecting the localconditions in Athens basin.     

Individual and simultaneous degradation of brominated high impact polystyrene and brominated acrylonitrile-butadiene-styrene and removal of heteroelements (Br,N, and O) from degradation oil by multiphase catalytic systems

Brominated high-impact polystyrene (HIPS-Br), which contained decabromodiphenyl ether flame retardant, and brominated acrylonitrile butadiene styrene (ABS-Br), which contained bromine-containing epoxy-type flame retardant, were degraded at 450°C individually and in a 1/1 mixture by a thermal and catalytic procedure using folded sheet mesoporous (FSM) and ZSM-5 zeolite in liquid phase contact mode. The two polymers produced similar degradation oils but at a higher yield for HIPS-Br. However, the composition and distribution of Br-, N-, and O-containing compounds depended on the type of flame retardant in HIPS-Br and ABS-Br. Multiphase catalytic systems consisting of FSM in liquid phase contact mode and various CaH-, FeO-, CoMo-, and NiMo-based catalysts, or combinations of these catalysts, in vapor phase contact mode were used to decrease the amount of heteroatoms (Br, N, and O) in the degradation oils. Each system gave particular results in terms of mass balance and concentrations of heteroatoms. A FSM (liquid phase contact)/CaHC (vapor phase contact) combination was the best catalytic system to remove Br-, N-, and O-containing compounds from degradation oils.     

Reductive decomposition of waste gypsum with SiO<Subscript>2</Subscript>, Al<Subscript>2</Subscript>O<Subscript>3</Subscript>, and Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> additives

From the point of view of a sustainable and environment-friendly society based on the recycling of material resources, it is preferable to utilize waste gypsum as a substitute for lime, which is currently produced by the calcination of limestone. In the present work, the reductive decomposition of CaSO₄ was investigated under an atmosphere of CO: 2 vol%, CO₂: 30 vol%, with N₂ as a carrier gas without and with the addition of SiO₂, Al₂O₃, or Fe₂O₃. It was found that the decomposition temperature of CaSO₄ was significantly reduced from 1673 K to 1223 K when only 5 wt% Fe₂O₃ was added to CaSO₄. In the case of the addition of SiO₂ or Al₂O₃ to CaSO₄, the decomposition temperature was reduced from 1673 K to 1623 K. This was due to the formation of composite oxides (calcium ferrite, calcium silicate, or calcium aluminate) during the reaction of CaSO₄ with the additives at a lower temperature. In addition, the formation of unfavorable product CaS was inhibited in the presence of 5 wt% Fe₂O₃, and this inhibition effect further increased as the addition of Fe₂O₃ was increased. In contrast, no significant effect on the inhibition of CaS formation was observed on the addition of SiO₂ or Al₂O₃.     

Effects of Mine Drainage on Breakdown of Aspen Litter in Mountain Streams

Rates of aspen litter breakdown were measured at 40 sites in streams of the Rocky Mountains of Colorado, U.S.A. The sites encompassed a range of effects of mine drainage, from pristine (no effects) to highly stressed. The pH, concentrations of dissolved zinc, and deposition rates of metal oxides (the three main stresses from mine drainage) were measured in each stream. Rates of litter breakdown were estimated from changes in mass of aspen leaves in litterbags. The biological communities associated with litter breakdown also were evaluated by measuring the biomass of shredding invertebrates in litterbags and the rate of microbial respiration on litter. Of the stresses from mine drainage, concentration of zinc and deposition rate of metal oxides were most closely related (negatively) to rate of litter breakdown. Biomass of shredding invertebrates was also negatively related to concentration of dissolved zinc and deposition of metal oxides. Microbial respiration was negatively related to deposition rate of metal oxides and positively related to concentration of nutrients. Both shredder biomass and microbial respiration were positively related to litter breakdown rate and, together, accounted for 79% of its variation. Recovery of litter breakdown in streams affected by mine drainage requires remediation that limits both dissolved and deposited metals.     

光催化氧化处理难降解污水的应用前景

随着工业的不断发展,环境污染日益严重,传统水处理工艺中的物理、生物方法不能满足水处理的需要。将光催化氧化法应用于气相和水相中一些难降解污染物的治理,研究结果表明,催化剂的选择、反应器的设计和对降解条件的优化是提高污染物光催化降解效率的关键因素。半导体光催化技术具有高稳定性、耐腐蚀、无毒的特点,在处理过程中不产生二次污染,有机污染物能被彻底无机化,因而这是一种洁净的处理技术。光催化技术为彻底解决水污染问题提供了新的手段,它在环境污染治理中有广阔的应用前景。     

自反应性化学物质的热危险性评价方法

笔者进行的研究工作 ,给出了利用C80微量量热仪所测得的自反应性化学物质的热流速曲线 ,从而求解该物质的化学反应动力学参数 ,以及在Semenov模型下求解其自加速分解温度SADT(Self AcceleratingDecompositionTemperature)的方法 ,并将一些有机过氧化物、氧化剂和可燃剂的混合物的自加速分解温度的推算结果与实测值进行了比较。实验证明 ,该推算方法结论准确 ,是一种安全、简便、实用的反应性化学物质热危险性的评价方法     

废旧塑料的综合利用

近年来 ,治理“白色污染”、消灭“白色公害”已成为全球的共识 ,从废旧塑料的最终处置、直接再生利用、改性再生利用、热分解以及与其他材料复合等几个方面综述了废旧塑料的综合利用途径 ,其中废旧塑料和其他材料复合的再生利用技术有很好的发展前途 ,将成为今后研究的新热点     

Impacts of meteorology and precursor emission change on O3 variation in Tianjin, China from 2015 to 2021

Deterioration of surface ozone (O₃) pollution in Northern China over the past few years received much attention. For many cities, it is still under debate whether the trend of surface O₃ variation is driven by meteorology or the change in precursors emissions. In this work, a time series decomposition method (Seasonal-Trend decomposition procedure based on Loess (STL)) and random forest (RF) algorithm were utilized to quantify the meteorological impacts on the recorded O₃ trend and identify the key meteorological factors affecting O₃ pollution in Tianjin, the biggest coastal port city in Northern China. After “removing” the meteorological fluctuations from the observed O₃ time series, we found that variation of O₃ in Tianjin was largely driven by the changes in precursors emissions. The meteorology was unfavorable for O₃ pollution in period of 2015-2016, and turned out to be favorable during 2017-2021. Specifically, meteorology contributed 9.3 µg/m³ O₃ (13%) in 2019, together with the increase in precursors emissions, making 2019 to be the worst year of O₃ pollution since 2015. Since then, the favorable effects of meteorology on O₃ pollution tended to be weaker. Temperature was the most important factor affecting O₃ level, followed by air humidity in O₃ pollution season. In the midday of summer days, O₃ pollution frequently exceeded the standard level (>160 µg/m³) at a combined condition with relative humidity in 40%-50% and temperature > 31°C. Both the temperature and the dryness of the atmosphere need to be subtly considered for summer O₃ forecasting.