Emission
Emission
Emission is generally considered the process of letting something out or releasing it. Heat that is expelled (or released) from a home’s furnace in the winter is a form of emission. In the context of ecology
and environmental science, the word emission generally refers to a release of a substance or energy to the environment. Often, emissions refer to substances or energy that are ecological stressors (something that causes stress), and can potentially cause deleterious changes.
Emission sources are of two broad types, point and diffuse. Point sources of emission are discrete and spatially localized. A volcano is a natural example of a point source of emission of gases and particulates to the atmosphere. Some point sources associated with human activities are automobiles, chimneys of homes, smokestacks of power plants and smelters, and aquatic discharge pipes for chemical effluent and waste heat of factories. In contrast, diffuse emissions occur over large areas from many, often indistinct sources. For example, although each is a small point source, the large numbers of houses and vehicles in cities collectively represent a large, diffuse source of emissions of pollutants into Earth’s atmosphere.
Emitted energy can be of two types, heat or electromagnetic. Heat is a type of kinetic energy, involving the vibration of atoms or molecules. The more vigorously these particles are vibrating, the greater the heat content of a substance. Discharges of warm water from power plants and factories are examples of the emission of heat.
Electromagnetic energy is the energy of photons, which are entities that have properties of both particles and waves. Electromagnetic energy is divided into spectral components on the basis of wavelength, and includes radio waves, infrared, visible (so-called because it is perceptible by the human eye), ultraviolet, x rays, and gamma radiation. Electromagnetic energy is generally emitted by a point source, whose emission spectrum can involve one or more of the categories just noted.
Emissions of materials can be from diffuse or point sources. Human activities result in emissions of many chemicals, which can be major pollutants that cause environmental damages. Some of the most dangerous of these emitted materials are gases such as sulfur dioxide, oxides of nitrogen (a mixture of nitric oxide and nitrogen dioxide), and carbon dioxide, particulates containing metals and organic compounds, and vapors of hydrocarbons, mercury, and other chemicals.
Emission is also used in other fields of science. In chemistry, the product of a chemical reaction, whether it be chemical or nuclear, is called an emission. In physics, the release or output of electromagnetic radiation in the form of energy is considered emission. In physiology, the human body can release various materials, each is called an emission.
See also Non-point source; Stress, ecological.
Emission
Emission
In the context of ecology and environmental science, the word emission generally refers to a release of a substance or energy to the environment. Often, emissions refer to substances or energy that are ecological stressors, and can potentially cause deleterious changes.
Emission sources are of two broad types, point and diffuse. Point sources of emission are discrete and spatially localized. A volcano is a natural example of a point sources of emission of gases and particulates to the atmosphere. Some point sources associated with human activities are automobiles, chimneys of homes, smokestacks of power plants and smelters, and aquatic discharge pipes for chemical effluent and waste heat of factories. In contrast, diffuse emissions occur over large areas from many, often indistinct sources. For example, although each is a small point source , the large numbers of houses and vehicles in cities collectively represent a large, diffuse source of emissions of pollutants into the atmosphere.
Emitted energy can be of two types, heat or electromagnetic. Heat is a type of kinetic energy, involving the vibration of atoms or molecules. The more vigorously these are vibrating, the greater the heat content of a substance. Discharges of warm water from power plants and factories are examples of the emission of heat.
Electromagnetic energy is the energy of photons, which are entities that have properties of both particles and waves. Electromagnetic energy is divided into spectral components on the basis of wavelength, and includes radio waves , infrared, visible (so-called because it is perceptible by the human eye ), ultraviolet, x rays , and gamma radiation . Electromagnetic energy is generally emitted by a point source, whose emission spectrum can involve one or more of the categories just noted.
Emissions of materials can be from diffuse or point sources. Human activities result in emissions of many chemicals that are important pollutants that cause environmental damages. Some of the most important of these emitted materials are gases such as sulfur dioxide , oxides of nitrogen (a mixture of nitric oxide and nitrogen dioxide), and carbon dioxide , particulates containing metals and organic compounds, and vapors of hydrocarbons, mercury, and other chemicals.
See also Non-point source; Stress, ecological.
Emission
Emission
Release of material into the environment either by natural or human-caused processes. This term is used especially in describing air pollution for volatile or suspended contaminants that result from processes such as burning fuel in an engine. Definitions of pollution are complicated by the fact that many of the materials that damage or degrade our atmosphere have both human and natural origins. Volcanoes emit ash, acid mists, hydrogen sulfide, and other toxic gases. Natural forest fires release smoke , soot, carcinogenic hydrocarbons , dioxins, and other toxic chemicals as well as large amounts of carbon dioxide . Do these emissions constitute pollution when they originate from human sources but not if released by natural processes? Is it reasonable to restrict human emissions if there are already very large natural sources of those same materials in the environment? An important consideration in answering these questions lies in the regenerative capacity of the environment to remove or neutralize contaminants. If we overload that capacity, a marginal additional emission may be important. Similarly, if there are thresholds for response, an incremental addition to ambient levels may be very important.
emission
e·mis·sion / iˈmishən/ • n. the production and discharge of something, esp. gas or radiation: cuts in carbon dioxide emissions. ∎ a thing emitted: choking on the noxious emission. ∎ an ejaculation of semen. ∎ the action of giving off radiation or particles; a flow of electrons from a cathode-ray tube or other source.