What are the adverse effects of local air pollution
Origin：Hefan Hit： Time：2020-03-14
Large-scale large-scale pollution that targets a region or a city is called regional pollution or urban pollution, which is the focus of China's current environmental protection work. Small-scale pollution that targets a single chimney or pollution is called local pollution, such as local atmospheric pollution caused by thermal power plants, non-ferrous metal smelters, iron and steel plants, polyvinyl chloride, dye factories, paper mills, and so on.
The adverse effects of air pollution on the urban (or regional) environment
This effect is mainly caused by the adverse changes in the physical, chemical and biological characteristics of the urban environment.
The adverse changes in physical characteristics are mainly manifested in increased smoke days, low visibility, and urban heat island effects. Particulate matter discharged into the atmosphere from various sources of pollution has a certain absorption and scattering effect on the sun's light, and the particulate matter can also act as a condensed nodule of fog. Therefore, it can reduce the radiation intensity of the sun directly to the ground. When the pollution is severe, the energy of the sun's radiation to the surface can be reduced to more than 40%. The atmosphere often becomes very turbid due to the presence of smoke, and sometimes the visibility is only a few meters.
The city's heat island effect is actually the thermal dyeing of the city's atmosphere. Urbanization has changed the composition and properties of the underlying surface. Artificial surfaces such as bricks, cement, glass, stone, and metal have replaced natural surfaces such as soil, grassland, and forest, changing the nature of reflection and radiation, and changing the near-surface. Layer exchange and ground roughness affect the physical properties of the atmosphere. Urban temperatures are higher than the four neighbours, often forming urban heat islands. The warm current in the central area of the city rises and spreads from the upper floors to the surrounding areas. The colder air in the suburbs is blown from the lower floors to the urban areas, forming a local flow. Although this enhances the air convection in the urban and suburban areas, it also causes pollutants to a certain extent Stuck in this local loop, it is not easy to spread to a larger area, and a pollutant curtain is often formed over the city.
Undesirable changes in chemical characteristics Changes in the level of chemical substances in the atmospheric chemical composition can cause undesirable changes in chemical characteristics. Pollutants such as smoke, dust, SO2, NOx, benzo [a] pyrene, etc., emitted by various sources such as industry, living, transportation, etc., are discharged into the atmosphere, increasing the level of pollutants in the atmosphere. It is the increase in the ground concentration of pollutants that will inevitably cause urban air pollution and cause adverse changes in academic characteristics. As a result, the incidence of endangering human health, causing cancer, respiratory diseases, and cardiovascular and cerebrovascular diseases is on the rise, and can make buildings, bridges, cultural relics, artworks, metal products exposed to the air, leather, textiles, etc. The qualitative and adverse changes in the goods have caused direct and indirect economic losses. In addition, it has adverse effects on urban green plants.
Bad changes in biological characteristics Bad changes in the biological characteristics of the atmospheric environment mainly refer to urban atmospheric biological pollution. Some cities have listed bacteria in 1m3 of air as monitoring and control indicators.
Local pollution caused by industrial pollution sources
The pollution caused by the exhaust gas from industrial areas and large and medium-sized industrial enterprises are all local pollution. For example, the fluorine pollution caused by some small electrolytic aluminum plants and some phosphate fertilizer plants caused by the release of vinyl chloride from the polyvinyl chloride plant caused abnormal surrounding areas. The fertility rate has increased significantly. Chlorine and hydrogen chloride pollution caused by electrolytic salt factories, etc .; atmospheric pollution such as hydrogen sulfide, malodor, and organic waste gas caused by various industrial sources. Although it is local pollution, quite a lot of heavily polluted areas are formed in the country, and pollution accidents occur from time to time, and it has become an urgent environmental problem.