The Change Of Ambient Air Quality Based On AERMOD Model

Lanzhou is the capital of Gansu Province, in the geometric center of China's land territory, Lanzhou City is one of the cities which air pollution is serious, especially in the winter .The air pollution is quite serious,that is a typical complex urban terrain and soot particles type of pollution. The implementation of《Heating of Lanzhou city planning (2006-2020)》is prevention and control of air pollution in the program of《in the primary prevention measures》in Lanzhou City. AERMOD model system is improved by the U.S. Environmental Protection Agency and modeled by the Ministry of Environmental Protection《Technical Guidelines for Environmental Impact Assessment Atmospheric Environment》(HJ / T 2. 2 -2009) .Then this model was recommended in the late 20th century. In this paper, we select the AERMOD model system for the《Heating of Lanzhou city planning (2006-2020)》is implement in Lanzhou City, then we will forecast that if air quality is improvement, and then guide the environmental management department to make more scientific, more precise control and management programs of the city's function zoning, pollution distribution, city size and other elements of urban environmental planning.In this paper, surface meteorological parameters are form the secondary stations of Lanzhou National Weather Observing ,we collected daily date in 2008year of meteorological data; altitude weather data form the Environmental Engineering Environmental Quality Assessment Center Simulation Laboratory of simulation of the mesoscale meteorological data.We considered that environmental features and meteorological conditions of Lanzhou City, this atmospheric forecast covers the whole of this range of Lanzhou City,from East to West is 33km, from north to south is19km that is the rectangular area.Then we grid area, grid spacing selected 1000m. Forecast period is implemented according to plan long-term heating plan (2020) and the heating plan is not implemented (in 2006 as the base year, the zero solution) ,which two of the heating period are the daily average concentration and annual average concentrations of predicted; predict pollution material factor of SO₂, PM₁₀; by HJ2.2-2008 recommendation model of meteorological preconditioning Aermet model; terrain by flat terrain into account, and do not pre-terrain parameters, calculated by AERMOD model system,we obtained (1)typical day of weather conditions, heating plan forward as planned (2020) and the heating plan is not implemented (in 2006 as the base year, the zero solution) are two of the heating period of major pollutants SO₂, PM₁₀ prediction of the range of environmental impacts analysis of whether excessive, excessive levels, exceeding the location, and evaluation within the drawing area appears when the maximum daily average concentration of the mass concentration corresponding to the contour map. (2) Analysis of long-term weather conditions, heating the planned implementation of the long-term planning (2020) and the heating plan is not implemented (in 2006 as the base year, the zero solution) are two of the heating period of major pollutants SO₂, PM₁₀ in predicting scope of environmental impact analysis is excessive, excessive levels, exceeding the scope and location, and draw the predicted concentrations within the contour map.We research in following: (1) through the forecast, the implementation of long-term planning (2020), Lanzhou city heating of SO₂, PM₁₀ daily average maximum concentration value accounting standard contribution rate was 19.39%, 5.29%, the average annual maximum concentration contribution to the value of the total scale were 5.88%, 1.17%; the Heping area after the implementation of urban heating in the planning of SO₂, PM₁₀ daily average maximum concentration value accounting standard contribution rate was 14.82%, 7.50%, with an annual contribution maximum concentration value accounting standard rate 3.49% and 1.08% respectively; Hekou area after the implementation of urban heating in the planning of SO₂, PM₁₀ daily average maximum concentration value accounting standard contribution rate was 9.08%, 4.61%, with an annual contribution maximum concentration value accounting standard rate of 2.49% and 0.76% respectively.Long-term planning and implementation of environmental sensitive points heating SO₂ daily average concentration was from16.7% reduction to 93.0%, an average annual reduction rate of the concentration of 74.0% 86.3%; PM₁₀ daily average concentration reduction rate of 5.7% 24.9%, average annual concentration reduction rate of 13.9% to 17.3%.Compared with the zero prediction programs, heating planning contributions to environmental air pollutants is far less than the value of the contribution of zero value under the program. Sensitive point stack through the prediction, as an alternative to the small coal-fired boilers, greatly improved the air quality in Lanzhou City, but the pressure of the air quality in Lanzhou City is still very large, sensitive points exceed the standard is still relatively common, which due to the background value too high, the contribution of heating bring the value of planning is not high. (2) Compare with the heating of Lanzhou city planning and the "zero solution" to the environmental benefits are significant, heating planning to reduce coal consumption in the heating of 95 million t / a in 2020. Dust emissions 10826.4t / a, SO₂ emissions 29197.2t / a, NOX emissions 10957.6t / a, reduction rates were 90.6%, 88.8%, 72.7%.(3) The absence of access to heating and air-capacity data of Lanzhou City, the capacity can only be compared to the whole year, so the actual proportion of total should be even greater. So we can see that air pollutants from emissions of heating accounted for very large proportion of Atmospheric environmental capacity in Lanzhou City. The first choice is that reduce heat emissions of air pollutants to improve air quality in Lanzhou City.Heating planning and implementation, long-term atmospheric soot, SO₂ the emissions are: 1124t / a, 3700t / a, were reduced compared with base year 88.9%, 86.2%. We can see that implementation of the plan, SO₂ emissions reduction targets can satisfy environmental requirements, but smoke can not satisfy the long-term environmental goals to reduce 90% of the requirements. To achieve environmental goals, we must reduction of 45.5% dust emissions based on the long-term, we can use the long-term clean energy to replace coal-fired to achieve the goals. By estimation, if the proportion of long-term clean energy to achieve target of 50%, then the dust emission is expected to achieve the intended environmental goals.