On April 1, Wu Xiaoqing, deputy director of the Ministry of Environmental Protection, disclosed that the primary source of pollution in Beijing, Hangzhou, Guangzhou and Shenzhen is motor vehicles. So what is the primary source of pollution in Lanzhou? What are the characteristics of pollution in Lanzhou? On April 2, the reporter learned from Lanzhou City and the National Academy of Environmental Sciences "Lanzhou Air Pollution Causes and Prevention Countermeasures" that in the air pollution of Lanzhou City, the industrial pollution load accounts for 35%, and the second is the motor vehicle. Exhaust gas, pollution load accounts for 20%.
Air pollution presents industrial, coal smoke, dust and vehicle exhaust gas pollution characteristics according to research and monitoring analysis. Lanzhou City air pollution is characterized by mixed pollution of industry, soot, dust and motor vehicle exhaust, of which industrial pollution sources account for The largest, followed by traffic pollution sources and domestic pollution sources, and the pollution point sources are widely distributed, the surface source range is large, and the flow sources grow rapidly. At the same time, it has obvious seasonal characteristics. In spring, it is mainly imported pollution such as dust and dust. In winter, low-altitude non-point source pollution such as soot is dominant, and moderate and severe pollution is mainly concentrated from November to March. Winter heating period.
Special geomorphology, unfavorable meteorological conditions, and fragile ecological impacts of blue sky and white clouds According to analysis, there are three main factors that influence and restrict the objective factors of air pollution control in Lanzhou.
The first is a special urban landscape. Lanzhou is located in the valley of the Loess Plateau. The terrain is obviously semi-enclosed and huge dumbbell type. The urban area is located in the basin, and the north and south mountains face each other. The relative height difference is 660 meters, the north and south are 2 to 8 kilometers wide, and the east and west extend about 35. Kilometers, the obvious basin topography caused the pollutants to not easily flow outward.
Unfavorable meteorological conditions are also one of the main factors. According to statistics, the average annual static wind rate in Lanzhou is 62.7%, the static wind rate in winter is over 80%, and the average daily wind speed is less than 0.8 m/s. The stable weather in winter accounts for more than 70%, and the atmospheric stratification is stable, forming an inversion layer, which is not conducive to the turbulent diffusion of atmospheric pollutants.
In addition, the fragile regional ecological environment also restricts Lanzhou's air pollution control. Lanzhou is located in a typical continental climate zone. It is dry and rainless all year round. The average annual rainfall is less than 300 mm, but the evaporation is 1800 to 2200 mm. The forest coverage rate is only 12.21%, which is lower than the national and provincial average. 8.15% and 1.2%, sandstorms and dusty weather are easy to spread and form.
Human factors are also important factors affecting Lanzhou's air quality. In addition to objective factors, human factors are also an important factor affecting Lanzhou's air quality.
In recent years, with the acceleration of urbanization and the increase of urban construction, the dust pollution caused by human factors has become increasingly serious, and it is difficult to prevent and control.
Motor vehicle exhaust pollution has also shown a significant increase in recent years. According to analysis, there are currently more than 650,000 motor vehicles in Lanzhou, and the annual growth rate has increased by more than 10%. In addition, the traffic in Lanzhou City is not smooth, the motor vehicle runs at low speed or idle speed, the exhaust emission increases, and the main traffic trunks form obvious pollution belts, and the proportion of nitrogen oxides in the air is accelerating.
Living coal pollution is also a major factor. The coal-fired heating boilers distributed in Lanzhou City, there are 100,000 small-scale stoves for urban and rural residents around the city, and more than 200 vertical small boilers for heating, and a considerable number of barbecue stalls along the street, which will cause structural pollution of coal during the heating period in winter. Especially outstanding.
In addition, the unreasonable industrial and energy structure has led to high industrial pollution in Lanzhou. The industrial foundation of Lanzhou was formed during the period of “First Five-Yearâ€, “Two-Five†and “Three-lineâ€. The industrial structure is mainly based on raw materials such as energy, petrochemicals and non-ferrous metallurgy. The heavy chemical industry accounts for nearly 80% of the total industry. %, the overall level of enterprise technology and equipment is not high, and “three high and one low†enterprises account for more than half. In addition, the energy structure is single, 80% of the energy consumption is dominated by coal, and the growth is rapid.
Industrial pollution accounts for 35% of air pollution, and vehicle exhaust pollution accounts for 20%.
According to "Lanzhou Air Pollution Causes and Prevention Countermeasures", in recent years, the three air pollutant loads such as inhalable particulate matter, sulfur dioxide and nitrogen oxides in Lanzhou City were 51%, 29.6% and 19.4%, respectively. China coal smoke and dust accounted for 21% (including industrial source coal dust contribution rate of 54.8%, coal-fired surface non-point source coal dust contribution rate of 45.2%; coal-fired dust contribution rate during heating period was 68.2%, coal-free dust contribution rate during non-heating period was 31.8 %), dust accounted for 33%, motor vehicle exhaust accounted for 14%, external input dust and other types of dust accounted for 32%; sulfur dioxide load accounted for 76.0% of industrial sources, coal-fired domestic source accounted for 18.5%, motor vehicle exhaust accounted for 4.5% %; industrial sources accounted for 35.1% of nitrogen oxide load, coal-fired non-point source accounted for 4.2%, and motor vehicle exhaust accounted for 60.7%.
Through weighted average, industrial pollution load in Lanzhou air pollution accounts for 35%, coal-fired non-point source pollution load accounts for 11%, dust pollution load accounts for 18%, motor vehicle exhaust pollution load accounts for 20%, external input dust and other types of dust The pollution load accounts for 16%.
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