Pollution

                          POLLUTION

Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants.  pollutant is a waste product that pollutes the environment, such as the air, water, or soil. A pollutant's severity is determined by three factors: its chemical type, concentration, extent of damage, and duration.    Although environmental pollution can be caused by natural events, the word pollution generally implies that the contaminants have an anthropogenic source – that is, a source created by human activities. Pollution is often classed as point source or nonpoint source pollution. In 2015, pollution killed nine million people worldwide (one in six deaths).This remained unchanged in 2019, with little real progress against pollution being identifiable. Air pollution accounted for 3⁄4 of these earlier deaths.

Major forms of pollution include air pollution, light pollution, litter, noise pollution, plastic pollution, soil contamination, radioactive contamination, thermal pollution, visual pollution, and water pollution.

The major forms of pollution are listed below along with the particular contaminants relevant to each of them:

• Air pollution: the release of chemicals and particulates into the atmosphere. Common gaseous pollutants include carbon monoxide, sulfur dioxide, chlorofluorocarbons (CFCs) and nitrogen oxides produced by industry and motor vehicles. Photochemical ozone and smog are created as nitrogen oxides and hydrocarbons react to sunlight. Particulate matter, or fine dust is characterized by their micrometre size PM₁₀ to PM_2.5.
• Electromagnetic pollution: the overabundance of electromagnetic radiation in their non-ionizing form, such as radio and television transmissions, Wi-fi etc. Although there is no demonstrable effect on humans there can be interference with radio-astronomy and effects on safety systems of aircraft and cars.
• Light pollution: includes light trespass, over-illumination and astronomical interference.
• Littering: the criminal throwing of inappropriate man-made objects, unremoved, onto public and private properties.
• Noise pollution: which encompasses roadway noise, aircraft noise, industrial noise as well as high-intensity sonar.
• Plastic pollution: involves the accumulation of plastic products and microplastics in the environment that adversely affects wildlife, wildlife habitat, or humans.
• Soil contamination occurs when chemicals are released by spill or underground leakage. Among the most significant soil contaminants are hydrocarbons, heavy metals, MTBE,^[8] herbicides, pesticides and chlorinated hydrocarbons.
• Radioactive contamination, resulting from 20th century activities in atomic physics, such as nuclear power generation and nuclear weapons research, manufacture and deployment. (See alpha emitters and actinides in the environment.)
• Thermal pollution, is a temperature change in natural water bodies caused by human influence, such as use of water as coolant in a power plant.
• Visual pollution, which can refer to the presence of overhead power lines, motorway billboards, scarred landforms (as from strip mining), open storage of trash, municipal solid waste or space debris.
• Water pollution, caused by the discharge of industrial wastewater from commercial and industrial waste (intentionally or through spills) into surface waters; discharges of untreated sewage and chemical contaminants, such as chlorine, from treated sewage; and releases of waste and contaminants into surface runoff flowing to surface waters (including urban runoff and agricultural runoff, which may contain chemical fertilizers and pesticides, as well as human feces from open defecation).

                         Pollution has been found to be present widely in the environment. There are a number of effects of this:

• Biomagnification describes situations where toxins (such as heavy metals) may pass through trophic levels, becoming exponentially more concentrated in the process.
  

  Global carbon dioxide emissions by jurisdiction (as of 2015)
• Carbon dioxide emissions cause ocean acidification, the ongoing decrease in the pH of the Earth's oceans as CO2 becomes dissolved.
• The emission of greenhouse gases leads to global warming which affects ecosystems in many ways.
• Invasive species can outcompete native species and reduce biodiversity. Invasive plants can contribute debris and biomolecules (allelopathy) that can alter soil and chemical compositions of an environment, often reducing native species competitiveness.
• Nitrogen oxides are removed from the air by rain and fertilise land which can change the species composition of ecosystems.
• Smog and haze can reduce the amount of sunlight received by plants to carry out photosynthesis and leads to the production of tropospheric ozone which damages plants.
• Soil can become infertile and unsuitable for plants. This will affect other organisms in the food web

                Pollution control is a term used in environmental management. It means the control of emissions and effluents into air, water or soil. Without pollution control, the waste products from overconsumption, heating, agriculture, mining, manufacturing, transportation and other human activities, whether they accumulate or disperse, will degrade the environment. In the hierarchy of controls, pollution prevention and waste minimization are more desirable than pollution control. In the field of land development, low impact development is a similar technique for the prevention of urban runoff.

Policy, law and monitoring/transparency/life-cycle assessment-attached economics could be developed and enforced to control pollution.^[59] A review concluded that there is a lack of attention and action such as work on a globally supported "formal science–policy interface", e.g. to "inform intervention, influence research, and guide funding".^[5]

Practices

• Recycling
• Reusing
• Waste minimisation
• Mitigating
• Pollution prevention
• Compost

Devices

• Air pollution control
  • Thermal oxidizer
• Dust collection systems
  • Baghouses
  • Cyclones
  • Electrostatic precipitators
• Scrubbers
  • Baffle spray scrubber
  • Cyclonic spray scrubber
  • Ejector venturi scrubber
  • Mechanically aided scrubber
  • Spray tower
  • Wet scrubber
• Sewage treatment
  • Sedimentation (Primary treatment)
  • Activated sludge biotreaters (Secondary treatment; also used for industrial wastewater)
  • Aerated lagoons
  • Constructed wetlands (also used for urban runoff)
• Industrial wastewater treatment
  • API oil-water separators^[20][60]
  • Biofilters
  • Dissolved air flotation (DAF)
  • Powdered activated carbon treatment
  • Ultrafiltration
• Vapor recovery systems
• Phytoremediation