During the period between 18 August and 22 September 2006, an ultraviolet
photometric O3 analyzer, a NO-NO2-NOx chemiluminescence
analyzer, and a quartz micro-oscillating-scale particle concentration
analyzer were simultaneously used for monitoring at three different heights
each at Beijing (325-m tower) and Tianjin (255-m tower). These towers belong
to the Institute of Atmospheric Physics (IAP) of the Chinese Academy of
Sciences (CAS) and to the Tianjin Municipal Meteorological Bureau,
respectively. These measurements were used to continuously measure the
atmospheric O3 and NOx volume-by-volume concentrations and the
PM2.5 mass concentration within a vertical gradient. When combined with
meteorological data and information on the variation of vertical
characteristics of the various atmospheric pollutants in the two cities,
analysis shows that these two cities were seriously polluted by both
PM2.5 and O3 during summer and autumn. The highest daily-average
concentrations of PM2.5 near the ground in Beijing and Tianjin reached
183 μg m-3 and 165 μg m-3, respectively, while the O3 concentrations reached 52 ppb and 77 ppb, and NOx concentrations
reached 48 ppb and 62 ppb for these two cities, respectively. The variations
in the daily-average concentrations of PM2.5 between Beijing and
Tianjin were demonstrated to be consistent over time. The concentrations of
PM2.5 measured in Beijing were found to be higher than those in
Tianjin. However, the overall O3 concentrations near the ground in
Tianjin were higher than in Beijing. NOx concentrations in Tianjin were
consistently lower than in Beijing. It was also found that PM2.5
pollution in Beijings atmosphere may also be affected by the pollutants
originating in and delivered from Tianjin, and that Ti 相似文献
Magma mixing structures from the lava flow of Lesbos (Greece) are analyzed in three dimensions using a technique that, starting from the serial sections of rock cubes, allows the reconstruction of the spatial distribution of magmas inside rocks. Two main kinds of coexisting structures are observed: (i) “active regions” (AR) in which magmas mix intimately generating wide contact surfaces and (ii) “coherent regions” (CR) of more mafic magma that have a globular shape and do not show large deformations. The intensity of mingling is quantified by calculating both the interfacial area (IA) between interacting magmas and the fractal dimension of the reconstructed structures. Results show that the fractal dimension is linearly correlated with the logarithm of interfacial area allowing discrimination among different intensities of mingling.
The process of mingling of magmas is simulated using a three-dimensional chaotic dynamical system consisting of stretching and folding processes. The intensity of mingling is measured by calculating the interfacial area between interacting magmas and the fractal dimension, as for natural magma mixing structures. Results suggest that, as in the natural case, the fractal dimension is linearly correlated with the logarithm of the interfacial area allowing to conclude that magma mixing can be regarded as a chaotic process.
Since chemical exchange and physical dispersion of one magma inside another by stretching and folding are closely related, we performed coupled numerical simulations of chaotic advection and chemical diffusion in three dimensions. Our analysis reveals the occurrence in the same system of “active mixing regions” and “coherent regions” analogous to those observed in nature. We will show that the dynamic processes are able to generate magmas with wide spatial heterogeneity related to the occurrence of magmatic enclaves inside host rocks in both plutonic and volcanic environments. 相似文献
Vanadium-bearing stone coal is a new vanadium resource;recovery ofV_2O_5 from the coal has been investigated.It has been found that a satisfactoryextraction of V_2O_5 depends on both the oxidation of V and its reaction with so-dium salt.V in the coal ash of Yushan mainly exists in two oxidation states:98%V(Ⅲ)and2%V(Ⅳ).The distribution of valency of V shows that organicmatter determines V valency at low temperatures,at about470℃,V(Ⅲ)iscompletely oxidized to V(Ⅳ);above500℃,the temperature is the most impor-tant factor for the oxidation of V .At higher temperatures no more V is oxidizedto V(Ⅴ);an equilibrium is established after92%of V is oxidized to V(Ⅴ).The roles of NaCl in the recovery of V_2O_5 from the coal ash were discussed.The best conditions for roasting are temperature750-800℃for1 h.underthe oxidation-chlorination atmosphere.When the ore:NaCl=100:10 by weight,η_roast reaches85.5%.According to the results,a flowsheet for V_2O_5 extrac-tion from coal ash has been proposed. 相似文献