Study On The Seasonal Variations Of The Atmospheric Environmental Capacity In Lanzhou

The study and the checking and ratifying of the atmospheric environmental capacity is the precondition and base of atmospheric pollution total amount control. The accurate calculation on atmospheric environmental capacity can provide scientific gist for the regional atmospheric pollution control and environmental planning. At the same time, the limited resources can also be fully utilized and promote the scientificity and systematization of the environmental management.After summarying and analyzing some domestic and overseas studies on the atmospheric environmental capacity calculating methods, A value method, which is the most simple mode, is adopted in this paper to account the atmospheric environmental capacity in Lanzhou. The PM₁₀, SO₂ and NO₂ are selected as the influence factors. In the process of calculating the atmospheric environmental capacity, the transportation and diffusion, dry deposition, wet deposition and chemical transformation courses are considered in this thesis.Taking Lanzhou city for example, the A value in the different seasons are calculated in this paper with the weather data. The results are as follows: the A value in spring is 4.32, for the summer is 4.62, the autumn is 1.54 and in winter it is 1.04. The results resolve the A value's uncertainty and random during the course of calculating the atmospheric environmental capacity. It improves the scientificity and rationality of the results about the atmospheric environmental capacity.The basic atmospheric environmental capacity in Lanzhou are PM₁₀ 40548 t/a, SO₂ 23315 t/a and NO₂ 15565 t/a respectively. The results indicate that the obvious seasonal variational rules of the basic atmospheric environmental capacity occurred in Lanzhou city: the removal quantity in spring and summer are much larger than that in autumn and winter.The quantity of the dry deposition eliminated in Lanzhou are PM₁₀ 2505 t/a, SO₂ 1234 t/a and NO₂ 175 t/a respectively.We collect the rainfall data in this study from 2000 to 2006 in Lanzhou, and we calculate all the pollutants' wet deposition velocity in different seasons and analyze the quantity of the wet deposition removed: PM₁₀ 697 t/a, SO₂ 9380 t/a and NO₂ 1725 t/a respectively. The removal quantity of the wet deposition in summer and autumn are much larger than that in winter and spring.In this thesis we calculate the chemical transformation velocity about the SO₂ and NO₂, and accounted the removal quantity of the chemical transformation: SO₂ 3012 t/a and NO₂ 296 t/a respectively. The removal quantity in spring and summer are much larger than that in autumn and winter.Various physical and chemical courses in the removal of the atmospheric pollutants are analyzed in this thesis. The results of environmental capacity can reflect the actual atmospheric environmental capacity in Lanzhou. Of course the results acquired in this paper can provide the scientific references for the atmospheric pollution control in Lanzhou city exactly.The results indicate that the basic atmospheric environmental capacity is selected for the total amount index of the PM₁₀. The total permitted emission quantity of the PM10 in spring is 15205 t, for the summer is 16261t, the autumn is 5420t and in winter it is 3661t. The basic atmospheric environmental capacity and the variational atmospheric environmental capacity are selected for the total amount index of the SO₂ and NO₂ in spring and summer; the basic atmospheric environmental capacity are selected for the total amount index of the SO₂ and NO₂ in winter and spring. The total permitted emission quantity of the SO₂ in spring is 10751t, for the summer is 20152t, the autumn is 3166t and in winter it is 1854t. The total permitted emission quantity of the NO₂ in spring is 6297t, for the summer is 8287t, the autumn is 2070t and in winter it is 922t.