Observations of nitrous acid and its relative humidity dependence in Shanghai

Nitrous acid, HNO2, is an important precursor of OH radicals in the troposphere. Measurements of HNO2 and NO2, using differential optical absorption spectroscopy （DOAS）, were performed in Shanghai, China for a period from October 22, 2004 to January 4, 2005. The mean （and median） hourly concentrations of HNO2 and NO2 during this period were 1.1 （0.7） ppb and 24 （21.4） ppb respectively. A correlation between HNO2/NO2 and PM10 mass concentrations was obtained. This correlation suggests that significant heterogeneous chemical production of HNO2 may occur through NO2 reactions on aerosol surfaces. This hypothesis was further supported by detailed analysis of selected pollution episodes in this study. At the same time, the water dependence of HNO2 formation was studied by analysis of relative humidity （RH）. It showed that the maximum HNO2/NO2 ratio was increased along with RH below 70% and inhibited at RH〉70%.

Fractal characteristic of microscopic pore structure of tight sandstone reservoirs in Kalpintag Formation in Shuntuoguole area,Tarim Basin

Using the fractal geometry method,the microscopic pore structures of tight sandstone reservoirs in Kalpintag Formation of Shuntuoguole area in Tarim Basin were conducted fractal characterization on the base of test analysis data such as physical property,cast thin section,scanning electron microscope and mercury injection,and the genetic mechanism of pore structure heterogeneity was investigated.The storage spaces are dominated by intergranular dissolved pore,intragranular dissolved pore and residual intergranular pore,and the throat type consists of the necking throat,lamellar throat,curved lamellar throat and tube-shaped throat.The microscopic structure type includes Type Ⅰ(fractal dimension≤2.350),Type Ⅱ(2.350<fractal dimension<2.580),Type Ⅲ(fractal dimension>2.580)and fracture type.The most favorable reservoirs with Type-Ⅰ microscopic pore structure are mainly distributed in the Upper Member of Kalpintag Formation,while the reservoirs with Type-Ⅱ and Type-Ⅲ microscopic pore structures are mainly in the Lower Member of Kalpintag Formation.The sedimentation controls the heterogeneity of microscopic pore structure,and the differences on composition and particle size of sandstone lead to differentiation of microscopic pore structures.The Lower Member of the Kalpintag Formation experiences stronger compaction and cementation but weaker dissolution than the Upper Member of the Kalpingtag Formation,and thus the microscopic pore structure of Upper Member of the Kalpintag Formation is significantly worse that of the Lower Member o the Kalpingtag Formation.The Upper Member of the Kalpintag Formation with high content of brittle mineral develops microscopic fractures due to tectonic rupture,thus the permeability is improved and the heterogeneity of microscopic pore structures is enhanced;but the Lower Member of Kalpintag Formation is characterized by attrition crushing of particles and strong compaction.