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The dissolution of the 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) from microscale particles (<250 μm) of the explosive formulation Composition B was examined and compared to dissolution from macroscopic particles (>0.5 mm). The dissolution of explosives from detonation soot was also examined. The measured mass transfer coefficients for the microscale particles were one to two orders of magnitude greater than the macroscopic particles. When normalized to particle surface area, mass transfer coefficients of microscale and macroscale particles were similar, indicating that the bulk dissolution processes were similar throughout the examined size range. However, an inverse relationship was observed between the particle diameter and the RDX:TNT mass transfer rate coefficient ratio for dry-attritted particles, which suggests that RDX may be more readily dissolved (relative to TNT) in microscale particles compared to macroscale particles. Aqueous weathering of larger Composition B residues generated particles that possessed mass transfer coefficients that were on the order of 5- to 20-fold higher than dry-attritted particles of all sizes, even when normalized to particle surface area. These aqueous weathered particles also possessed a fourfold lower absolute zeta-potential than dry-attritted particles, which is indicative that they were less hydrophobic (and hence, more wettable) than dry-attritted particles. The increased wettability of these particles provides a plausible explanation for the observed enhanced dissolution. The wetting history and the processes by which particles are produced (e.g., dry physical attrition vs. aqueous weathering) of Composition B residues should be considered when calculating mass transfer rates for fate and transport modeling. 相似文献
13.
本文系统介绍了城市水污染集中控制的系统结构,提出了城市水污染集中控制的最佳系统构成,论述了该系统的建立方法和程序. 相似文献
14.
Salinization and sodicity are obstacles for vegetation reconstruction of coastal tidal flat soils. A study was conducted with flue gas desulfurization(FGD)-gypsum applied at rates of 0, 15, 30, 45 and 60 Mg/ha to remediate tidal flat soils of the Yangtze River estuary.Exchangeable sodium percentage(ESP), exchangeable sodium(ExNa), p H, soluble salt concentration, and composition of soluble salts were measured in 10 cm increments from the surface to 30 cm depth after 6 and 18 months. The results indicated that the effect of FGD-gypsum is greatest in the 0–10 cm mixing soil layer and 60 Mg/ha was the optimal rate that can reduce the ESP to below 6% and decrease soil p H to neutral(7.0). The improvement effect was reached after 6 months, and remained after 18 months. The composition of soluble salts was transformed from sodic salt ions mainly containing Na~+, HCO_3~-+ CO_3~(2-)and Cl-to neutral salt ions mainly containing Ca~(2+)and SO_4~(2-). Non-halophyte plants were survived at 90%. The study demonstrates that the use of FGD-gypsum for remediating tidal flat soils is promising. 相似文献
15.
沈阳市冬季一次典型大气污染过程特征和成因分析 总被引:1,自引:1,他引:0
2013年11月18日~25日沈阳地区出现一次典型空气污染过程。采用单颗粒气溶胶质谱仪(SPAMS),并结合气象条件分析了该次污染的成因和细颗粒物的污染特征。结果表明,不利于污染物扩散的气象条件是重污染发生的主要原因,低空排放的积累可能是造成这次污染的又一重要原因。从细颗粒物成分上看,污染过程中有机碳颗粒占比明显增加,有机物污染较为严重,颗粒物间混合加剧;从来源上看,机动车尾气、工业排放和燃煤的占比较高。 相似文献
16.
在2000年、2005年和2010年遥感数据支持下,通过对生态系统类型的辨识,获得大伙房水库饮用水源保护区生态系统类型数据,并从生态系统组成、变化及变化特征3个方面对其进行深入分析。结果表明:近10年来,大伙房水库饮用水保护区内森林和水体与湿地减少,人工生态系统增加,面积变化相对较小。自然生态系统的破坏在2000~2005年间比2005~2010年间严重,且集中在一级保护区外,以准保护区内居多。 相似文献
17.
We investigated the spatial variability of sediment organic matter content and composition in three areas (A, B and C) of the Northwestern Adriatic Sea, subjected to a putative gradient of trophic state ( i.e. , increasing distance from the Po river outflow) in order to determine the appropriate sample size and replication. The analysis of the mesoscale variability was carried out comparing variability on the scale of meters ( i.e. among different deployments) with the variability observed on a scale of several kilometres ( i.e. among different sampling areas). Sediment samples, collected on April 1999, October 1999, April and October 2000, were analysed for chloropigment content (chlorophyll-a and phaeopygments) and protein, carbohydrate and lipid concentrations. Chloropigment, protein, carbohydrate and lipid concentrations were high, indicating that this system shares trophic conditions typical of highly productive environments. All organic matter components displayed a distribution independent from the increasing distance from the Po river outflow and a clear spatial variability, characterised by significant differences among different areas, but not among deployments. Carbohydrates were the biochemical compound displaying the highest spatial variability among the three areas. Chloropigment, protein, carbohydrate and lipid concentrations displayed also significant temporal changes. When spatial and temporal variability were compared, chlorophyll-a, phaeopigment and protein concentrations displayed a higher temporal than spatial variability. Conversely, for carbohydrates and lipids spatial and temporal variability was of the same order of magnitude. Organic matter composition displayed limited changes among areas, but a strong temporal variability. The results from the Adriatic sea suggest that analyses from sediments collected from a single deployment are sufficient for assessing organic matter concentration and composition over areas of several hundreds of square meters. However, for estimating organic matter composition over larger spatial scales ( i.e. miles) the identification of different sampling areas is needed. 相似文献
18.
经过对多种炼厂废料的大量实验比较分析,由于A#剂与B#剂在化学组成上具有互补性,可以将二者按一定比例混合作为复合再生剂。通过一定比例复合再生剂的调和作用,成功地使废旧沥青再生。再生后沥青性质完全满足重交通道路石油沥青质量标准(GB50092-96)的要求。 相似文献
19.
20.
Thermal volatilization is explored as a means of inferring the chemical composition of atmospheric aerosol particles with
diameters smaller than 10 nm (nanoparticles). Such particles contain too little mass for quantitative chemical determination
by traditional analytical methods. Aerosols were subjected to increasing temperature in an oven and particle loss was measured
as a function of temperature with the TSI model 3025 ultrafine condensation particle counter (UCPC), which is capable of counting
particles with diameters as small as 3 nm. Particle nucleation was observed down stream of the oven when it was heated above
about 400°C. To reduce this artifact, the sample air down stream of the oven was cooled to condense the hot gases and/or the
freshly nucleated particles before they reached the UCPC. Controlled experiments were done with pure ammonium sulfate (NH4)2SO4 particles. The experimental design was optimized based on the known concentration of pure (NH4)2SO4 particles vaporized in the oven and the diffusion of this material to the walls of the sampling tube before the particle
counter. 相似文献