Environmental Pollution

Types of Environmental Pollution

Pollutants can occur in any phase (solid, liquid, and gas) and can even be in the form of energy transfer such as heat, light, or noise. Let's have a look at some examples of environmental pollution:

Air pollution

Air pollution is caused by the release of gaseous particles, molecules, and particulates into the atmosphere. Small particulates are released as by-products from industrial reactions at high temperatures and pressures and from the exhaust pipes of vehicles. Dangerous gaseous molecules such as greenhouse gases (carbon dioxide, methane, ozone, nitrous oxide), sulphur dioxide, and chlorofluorocarbons (CFCs) are released via the combustion of fossil fuels, industrial processes, agriculture, and deforestation.

Water pollution

Water pollution involves the addition of polluting gaseous, liquid, and solid particles, molecules, or particulates that alter the composition of a water source. There are many causes of water pollution from human activity: the overapplication of pesticides and fertilisers in agriculture may cause them to runoff into nearby waters, industrial discharge contains dangerous chemicals like metal compounds, solvents, acids, and alkalis, while improperly treated sewage contains millions of disease-carrying pathogens and unwanted nutrients. The addition of heat energy can pollute the water too, this can gradual as a result of global warming or instant from power plant cooling water.

Soil Pollution

Soil pollution involves the influx of unwanted chemicals to soils, causing them to become contaminated and less fertile. The overuse of fertilisers can cause soils to contain too many nutrients, while the overuse of pesticides can poison soils and reduce biodiversity. Industrial discharge from landfills can introduce a host of unwanted chemicals (hydrocarbons, metal compounds, radioactive elements) to soils. Intensive agriculture such as ploughing and tillage can physically disturb soils and make them more vulnerable.

Light Pollution

Light pollution concerns any change to the normal level of light (ultraviolet or infrared radiation) to a location. Highly developed cities are the biggest driver of light pollution because of the widespread use of neon and fluorescent lights (they emit ultraviolet radiation). Abnormally bright skies can confuse wildlife and cause eye defects. Ultraviolet radiation can cause genetic mutations and cancer.

Figure 1: hotspots of light pollution in Europe.

Noise pollution

Noise pollution is an increase in the amount of noise heard in a certain area. Causes of noise pollution include heavy industrial machinery and vehicles (e.g. on a construction site), or loudspeakers and megaphones at events with lots of people. Noise pollution can put stress on ecosystems and people that live near the source of the noise.

Effects of Environmental Pollution

Now that we have looked at the types of environmental pollution and what causes them, let's have a look at the effects:

Climate Change

Anthropogenic air pollution is the major driver behind modern climate change. Greenhouse gas emissions (carbon dioxide, methane, nitrous oxide) contribute to the greenhouse effect in the atmosphere and warm the Earth's surface. Environmental implications of a warming planet are melting ice sheets, rising sea levels, increased precipitation, and more frequent severe weather.

Figure 2: melting ice sheets from global warming.

Human Health

Dangerous particulates released from industry and vehicles (soot, dust, metals) can damage human respiratory systems and cause cancer. The release of CFCs into the atmosphere depletes the ozone layer meaning that more ultraviolet radiation reaches the Earth. UV radiation increases the chance of genetic mutation and eye defects. Drinking polluted water can cause cholera, typhoid, and hepatitis A in humans, whereas using polluted water for washing can cause skin irritation and fluorosis when brushing teeth with it. Polluted soils can result in disease spreading in agricultural produce. If this disease is not noticed, it can spread between human populations.

Aquatic Ecosystems

25% of carbon dioxide emissions are absorbed into the oceans causing ocean acidification, which impairs the growth of organisms requiring carbonates for their shells and exoskeletons. UV radiation from ozone layer depletion can affect the developmental stages of larvae and producer populations too. Water pollution is a massive concern for aquatic ecosystems. The release of toxic, radioactive, and carcinogenic chemicals can kill wildlife species. Sedimentation fluxes from industrial and agricultural discharge can smother producers and cause alternative bottom-dwelling populations to rise in high-nutrient conditions. Algal blooms from nutrient overload can result in anoxic dead zones where no life can survive.

Terrestrial Ecosystems

Here are a few examples of how environmental pollution is destroying terrestrial ecosystems.

• Melting ice sheets and rising sea levels are destroying habitats in polar regions.
• Droughts and more frequent severe weather are causing habitat fragmentation in warmer regions.
• Dangerous particulates from industry and vehicles can clog respiratory systems and cause cancer in animals too.
• Contaminated drinking water can poison wildlife and spread disease in ecosystems.
• Acid rain will damage habitats and acidify soils.
• Contaminated soils from industrial and agricultural runoff do not support as many producer populations and can affect the food chains of entire ecosystems.
• Noise and light pollution will confuse and stress animals and may force them to migrate to unsuitable habitats.

Agriculture

Overuse of fertilisers can break down agroecosystems. Some wild plants will be unable to survive in a high-nutrient environment and local aquatic ecosystems may be affected. Therefore, the agroecosystem will function less effectively causing crops to be more susceptible to disease, while irrigation of nearby waters will be negatively impacted. The use of unnatural pesticides will contaminate soils and disrupt interspecies dynamics within the ecosystem. Overgrazing of pastures can restrict the ecological succession of soils.

Environmental Pollution Impact Factors

The rate at which pollution disperse and pollutants degrade to release dangerous chemicals is important in assessing how dangerous a point source of pollution will be.

Dispersal

Here are the factors that affect the dispersal of the different types of environmental pollution:

• Air pollution: the speed and direction of wind currents can tell us which locations are likely to receive the most air pollution (locations downwind of highly industrial areas are susceptible to air pollution). If air is more humid, the particles are more likely to become denser and be deposited into soils and waters.
• Water pollution: the speed and direction of water currents determine which parts of the ocean may receive the most water pollution. The rate of runoff of contaminated soils will happen more quickly when there is more precipitation and the slope is steeper (greater gravitational force pulling the water downwards). Water pollutants will stick to adsorbent materials and be concentrated in areas with a high concentration of them.
• Soil pollution: aerated soils will allow contaminants to pass through them more quickly. Increased runoff from rainfall can result in soil pollution on a wider scale as well.

Degradation

The rate at which pollutants degrade is important because they will often release poisonous chemicals and toxins as they are broken down. Here are some factors that affect the rate of degradation:

• Temperature: decomposing microorganisms will break down matter much quicker in warmer conditions. They will release vast amounts of nutrients and poisonous toxins.
• Moisture: microorganisms thrive in moist conditions too so decomposition rates will be high.
• pH: the presence of alkaline substances in the soil can help to neutralise acidic soils caused by acid deposition. Microorganisms work faster at specific pH's as well.
• Oxygen availability: aerobic decomposers are much more efficient at breaking down matter than anaerobic ones, and require a consistent supply of oxygen to survive.