Types of urban disasters
Five types of urban disasters, including urban haze, photochemical pollution, heat island effect, solid waste, and groundwater pollution disasters.
1. Haze
Haze weather is a state of atmospheric pollution. Haze is a general expression for the excessive content of various suspended particulate matter in the atmosphere, especially PM2.5 ( Particles with an aerodynamic equivalent diameter of less than or equal to 2.5 microns) are considered to be the "culprits" causing haze weather.
With the deterioration of air quality, haze weather phenomena are increasing and the hazards are aggravating. Many areas in China incorporate the haze weather phenomenon into fog as a disastrous weather warning and forecast.
2. Photochemical pollution
Photochemical smog is mainly caused by automobile exhaust and industrial waste gas emissions. Olefin hydrocarbons and nitrogen dioxide (NO2) in automobile exhaust are emitted After entering the atmosphere, NO and NO2 are photochemical pollution gases that are harmful to the human body.
After absorbing the energy of sunlight, the molecules of these substances will become unstable, destroy the original chemical chains, and form new substances. This chemical reaction is called a photochemical reaction, and its product is highly toxic photochemical smog.
3. Urban heat island effect
Cities are becoming "higher" due to factors such as a large amount of artificial heating, high heat storage bodies such as buildings and roads, and a reduction in green spaces. The temperature in the city is significantly higher than in the outer suburbs.
On the near-surface temperature map, the temperature in the suburbs changes very little, while the urban area is a high-temperature area, just like an island protruding from the sea. Because this kind of island represents a high-temperature urban area, it is vividly Called urban heat island.
The main factors that form the urban heat island effect include urban underlying surface, artificial heat sources, water vapor influence, air pollution, reduction of green space, population migration and other factors.
4. Municipal solid waste
Since there is no suitable place for treatment and disposal, solid waste is dumped at will, piled up in large quantities and handled improperly, which not only hinders the city appearance, but also affects urban environmental sanitation. . At present, with the rapid increase of urban population, urban domestic waste is increasing at an annual rate of 8% to 10%, and solid waste is facing the difficult situation of having nowhere to house it.
It seriously affects environmental sanitation and produces "visual pollution". Moreover, the piled urban domestic garbage is very easy to ferment and decay, producing stench, causing mosquitoes, flies, rats, etc. to breed and multiply, and easily cause the spread of diseases.
5. Groundwater pollution
The deterioration of groundwater quality due to human factors. The main causes of groundwater pollution are: industrial wastewater is discharged directly underground, contaminated surface water intrudes into the underground aquifer, human and animal feces or contaminated water due to excessive use of pesticides seeps into the ground, etc.
The result of pollution is an increase in the content of harmful components such as phenol, chromium, mercury, arsenic, radioactive substances, bacteria, organic matter, etc. in groundwater. Contaminated groundwater is harmful to human health and industrial and agricultural production.
Baidu Encyclopedia - Smog
Baidu Encyclopedia - Photochemical Pollution
Baidu Encyclopedia - Urban Heat Island Effect
Baidu Encyclopedia - —Municipal solid waste
Baidu Encyclopedia — Groundwater pollution