Pollution in the atmosphere Flashcards
(31 cards)
What are pollutants?
At certain times or places, the troposphere contains natural and human-caused gases, particles, and other substances in amounts that are harmful to humans or cause environmental damage.
What are some sources of natural pollutants?
Natural sources produce greater quantities of air pollutants—nitrogen oxides, carbon monoxide, hydrocarbons from plants and trees, and carbon dioxide—than do sources attributable to humans. Volcanoes, forest fires, and dust storms are the most significant sources, based on the volume of smoke and particulates produced and blown over large areas. However, pollen from crops, weeds, and other plants can also cause high amounts of particle pollution, triggering asthma as well as other adverse human health effects.
What are the particulates produces by natural pollution events called?
The particulates produced by these events are also known as aerosols and include the liquid droplets and suspended solids that range in size from visible water droplets and pollen to microscopic dust.
What eruption in 1991 was a dramatic natural source of air pollution?
A dramatic natural source of air pollution was the 1991 eruption of Mount Pinatubo in the Philippines (discussed in Chapter 1), probably the 20th century’s second-largest eruption. This event injected about 18 million tonnes of sulfur dioxide (SO2) into the stratosphere. The spread of these emissions is shown in a sequence of satellite images
How do wildfires affect air pollution?
Wildfires are another source of natural air pollution and occur frequently on several continents (Figure 3.5). Soot, ash, and gases darken skies and impair human health in affected regions. Wind patterns can spread the pollution from the fires to nearby cities, closing airports and forcing evacuations to avoid the health-related dangers. Satellite data show smoke plumes travelling horizontally for distances up to 1600 km. Smoke, soot, and particulates can be propelled vertically as high as the stratosphere.
What is the connection between climate change and wild fire occurrence?
In 2006, scientists established a connection between climate change and wildfire occurrence in the western United States, where higher spring and summer temperatures and earlier snowmelt result in a longer fire season. These connections are valid for Canada (see Chapter 5 Geosystems Now), and indeed occur across the globe, as in drought-plagued Australia, where thousands of wildfires burned millions of hectares in recent years.
What is the Anthropogenic atmosphere ?
Earth’s future atmosphere, so named because humans appear to be the principal causative agent.
How many deaths dose air pollution cause worldwide?
Anthropogenic air pollution remains most prevalent in urbanized regions. According to the World Health Organization, urban outdoor air pollution causes an estimated 1.3 million deaths worldwide.
Describe Carbon monoxide
CO
Incomplete combustion of fuels, mainly vehicle emissions
Odourless, colourless, tasteless gas. Toxic due to affinity for hemoglobin. Displaces O2 in bloodstream; 50 to 100 ppm causes headaches and vision and judgment losses.
Nitrogen oxides
NOx (NO, NO2)
Agricultural practices, fertilizers, and high temperature/pressure combustion, mainly from vehicle emissions
Reddish-brown choking gas. Inflames the respiratory system, destroys lung tissue. Leads to acid deposition.
Volatile organic compounds
VOCs
Incomplete combustion of fossil fuels such as gasoline; cleaning and paint solvents
Prime agents of surface ozone formation.
Ozone
O3
Photochemical reactions related to motor vehicle emissions
Highly reactive, unstable gas. Ground-level ozone irritates human eyes and respiratory system. Damages plants.
Peroxyacetyl nitrates
PANs
Photochemical reactions related to motor vehicle emissions
No human health effects. Major damage to plants, forests, crops.
Sulfur oxides
SOx (SO2, SO3)
Combustion of sulfur-containing fuels
Colourless, but with irritating smell. Impairs breathing and taste threshold. Causes human asthma, bronchitis, emphysema. Leads to acid deposition.
Particulate matter
PM
Industrial activities, fuel combustion, vehicle emissions, agriculture
Complex mixture of solid and liquid particles including dust, soot, salt, metals, and organics. Dust, smoke, and haze affect visibility. Black carbon may have a critical role in climate change. Various health effects: bronchitis, pulmonary function.
Carbon dioxide
CO2
Complete combustion of fossil fuels
Principal greenhouse gas
What contributes the most Sulfur oxides and particulates?
Stationary pollution sources, such as electric power plants and industrial plants that use fossil fuels, contribute the most sulfur oxides and particulates. Concentrations are focused in the Northern Hemisphere, especially over eastern China and northern India.
What is the major component of anthropogenic air pollution?
Although not generally present in human environments until the advent of the automobile, photochemical smog is now the major component of anthropogenic air pollution; it is responsible for the hazy sky and reduced sunlight in many of our cities
What is Photochemical smog?
Photochemical smog results from the interaction of sunlight and the combustion products in automobile exhaust, primarily nitrogen oxides and volatile organic compounds (VOCs), such as hydrocarbons that evaporate from gasoline. Although the term smog—a combination of the words smoke and fog—is generally used to describe this pollution, this is a misnomer.
How is NO2 produced and how dose it affect air quality?
The high temperatures in automobile engines produce nitrogen dioxide (NO2), a chemical also emitted to a lesser extent from power plants. NO2 is involved in several important reactions that affect air quality:
Interactions with water vapour to form nitric acid (HNO3), a contributor to acid deposition by precipitation, the subject of Focus Study 3.2.
Interactions with VOCs to produce peroxyacetyl nitrates, or PANs, pollutants that damage agricultural crops and forests, although they have no human health effects.
Interactions with oxygen (O2) and VOCs to form ground-level ozone, the principal component of photochemical smog.
how car exhaust is converted into photochemical smog
. In the photochemical reaction, ultraviolet radiation liberates atomic oxygen (O) and a nitric oxide (NO) molecule from the NO2. The free oxygen atom combines with an oxygen molecule, O2, to form the oxidant ozone, O3. The ozone in photochemical smog is the same gas that is beneficial to us in the stratosphere in absorbing ultraviolet radiation. However, ground-level ozone is a reactive gas that damages biological tissues and has a variety of detrimental human health effects, including lung irritation, asthma, and susceptibility to respiratory illnesses.
What is Industrial smog
Air pollution that is associated with coal-burning industries; it may contain sulfur oxides, particulates, carbon dioxide, and exotics
How dose sulfur dioxide react in the environment.
Once in the atmosphere, sulfur dioxide (SO2) reacts with oxygen (O) to form sulfur trioxide (SO3), which is highly reactive and, in the presence of water or water vapour, forms tiny particles known as sulfate aerosols. Sulfuric acid (H2SO4) can also form, even in moderately polluted air at normal temperatures. Coal-burning electric utilities and steel manufacturing are the main sources of sulfur dioxide
What is particulate matter?
The diverse mixture of fine particles, both solid and liquid, that pollute the air and affect human health is referred to as particulate matter (PM), a term used by meteorologists and regulatory agencies such as the Meteorological Service of Canada and the U.S. Environmental Protection Agency. Other scientists refer to these particulates as aerosols. Examples are haze, smoke, and dust, which are visible reminders of particulates in the air we breathe.
