http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/57 Tue, 19 May 2026 08:54:00 GMT 2026-05-19T08:54:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/280 Photochemical smog introduction and episode selection for the ground-level ozone in Hanoi, Vietnam Dam, Duy An; Hoang, Xuan Co; Nguyen, Thi Kim Oanh Ozone (O3) is a secondary pollutant formed in the atmosphere throughout a complex non-linear chemical reaction involving two classes of precursors: the reactive volatile organic compounds (VOCs) and the oxides of nitrogen (NOx) in the presence of sunlight. The rapid urbanization and industrialization in Vietnam have brought about high air pollutant emissions including the O3 precursors. Ground level O3 may already be high in large cities like Hanoi and Ho Chi Minh City. The O3 episode is very important for scene of view of photochemical smog in Hanoi. Ozone episodes are selected on the days which have a high concentration that lasts for at least two days time. During the episode selection, ozone concentrations larger than 46ppb were observed at two stations (the Lang and Lac Long Quan stations) in March. The maximum value of 74ppb was measured at the Lang station at 14:00 on March 3. This episode was observed in a common meteorological condition for this time of the year. VNU Journal of Science, Earth Sciences. Vol. 24 (2008), No. 4, P. 169-175 Tue, 01 Jan 2008 00:00:00 GMT http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/280 2008-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/279 Assessment of the influence of interpolation techniques on the accuracy of digital elevation model Tran, Quoc Binh; Nguyen, Thanh Thuy Digital Elevation Model (DEM) is an important component of GIS applications in many socio-economic areas. Especially, DEM has a very important role in monitoring and managing natural resources, preventing natural hazards, and supporting spatial decision making. Usually, DEM is built by interpolation from a limited set of sample points. Thus, the accuracy of the DEM is depended on the used interpolation method. By analyzing the data of experimental DEM creation using three popular interpolation techniques (inverse distance weighted - IDW, spline, and kriging) in four different survey projects (Thai Nguyen, Go Cong Tay, Co Loa, and Duong Lam), the paper has made an assessment of influence of interpolation technique on the DEM accuracy. Based on that, some recommendations on choosing interpolation technique has been made: for mountainous areas the spline regularized is the most suitable, for hilly and flat areas, the IDW or kriging ordinary with exponential model of variogram are recommended. VNU Journal of Science, Earth Sciences. Vol. 24 (2008), No. 4, P. 176-183 Tue, 01 Jan 2008 00:00:00 GMT http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/279 2008-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/278 Estimation of emission factors of air pollutants from the road traffic in Ho Chi Minh City Ho, Minh Dzung; Dinh, Xuan Thang The estimation of emissions largely depends on the quality of emission factors used for calculation. The study on the estimation of emission factors is important for calculating the emission of air pollutants from road traffic in Ho Chi Minh City (HCMC). The result of this study is the selection of a suitable method and tracer for estimating emission factors of 15 volatile organic compounds (VOCs) from C2-C6 and NOx from road traffic in HCMC. The survey has been carried out in 3/2 Street, District 10, HCMC from January to March 2007. Three VOCs compounds with high average emission factors are hexane (59,7 ± 9,2 mg/km.veh.), iso-pentane (52,7 ± 7,4 mg/km.veh.) and 3-methylpentane (36,1 ± 3,6 mg/km.veh.) and the average emission factor of NOx is 0,20 ± 0,03 g/km.veh. Besides, the emission factors of air pollutants for motorcycles, light-duty vehicles and heavy-duty vehicles are calculated by using the linear regression method. VNU Journal of Science, Earth Sciences. Vol. 24 (2008), No. 4, P. 184-192 Tue, 01 Jan 2008 00:00:00 GMT http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/278 2008-01-01T00:00:00Z http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/277 A new Environmental Poverty Index (EPI) for monitoring system in the SEA (Strategic Environmental Assessement) procedure Nguyen, Dinh Hoe In this paper, the authors apply the HPI index of UNDP 1995 to clarify the poverty levels of the poor living in six environmental poverty sectors according to ADB, 2008, in order to form a new Environmental Poverty Index (EPI) of national and provincial levels prospectively. This index is easy to communicate worldwide. To clarify the poverty levels of the environmental poverty in environmental sectors, a set of six environmental poor livelihood indicators (EPLI) is also proposed. The index and indicators are fit well the requirement of a monitoring system of the SEA procedure by Circular No 05/2008/TT-BTNMT issued by Vietnam Ministry of Natural Resources and Environment. Two methods are proposed to calculate EPI: Unweight method: EPI= Σ= n i HPIi n 1 1 Weight method: EPI = Σ Σ = = × n i i i n i HPIi C C 1 1 / where: i - the environmental poverty sector number i; n - the total number of environmental poverty sectors (imax=6); HPIi - the UNDP's human poverty index of the environmental poverty sector i; Ci - the weight of HPIi. VNU Journal of Science, Earth Sciences. Vol. 24 (2008), No. 4, P. 193-201 Tue, 01 Jan 2008 00:00:00 GMT http://tainguyenso.vnu.edu.vn/jspui/handle/123456789/277 2008-01-01T00:00:00Z