Environmental Pollution: Types, Causes, and Effects
1. Introduction
Pollution refers to the transmission and spread of toxic fumes or gases through mediums such as the atmosphere and water, as well as the presence of dust and microbial germs from human activity.
Modern development and technological progress have led to various forms of pollution that disrupt the physical and mental balance of human beings. Consequently, the current pollution problem is more critical than ever before. Some prevalent types of pollution include:
- Air pollution
- Pollution of waters, rivers, and lakes
- Sea pollution
- Ocean pollution
2. Air Pollution
In large cities, air pollution results from the release of gases from motor vehicle ignition, heating appliances, and industrial activities. These pollutants, released as gases, vapors, or solid particles, can remain suspended in the atmosphere at higher-than-normal levels, harming human, animal, and plant life and health.
The atmosphere absorbs a significant amount of solar radiation, including ultraviolet rays. The increase in carbon dioxide in the atmosphere due to the burning of coal and oil leads to a warming of the air and seas. This causes a chemical imbalance in the biosphere, producing a high amount of carbon monoxide, which is highly toxic to living organisms.
Air pollution predominantly originates from industrial combustion, primarily from electricity generation and automobiles. Other toxic substances, such as lead and mercury, also contribute to atmospheric pollution. It is crucial for residents of large cities to recognize that protecting the ecological environment is a primary need. Legislation should regulate substances released into the atmosphere and establish concentration limits.
Polluted air affects our daily lives, manifesting in various ways, such as eye irritation, conjunctival disorders, respiratory tract irritation, and exacerbation of bronchopulmonary diseases.
Several measures can help mitigate air pollution:
- Use appropriate fuel for domestic heating and industry.
- Utilize filters in chimneys to ensure proper function.
- Maintain motor vehicles in good condition.
- Avoid burning leaves or garbage.
Ecologists in Action
Ecology encompasses a set of sciences that study the relationships between living beings and their environment. The unit of study in ecology is the ecosystem, which comprises individuals of different species and their environment. The objective of ecology is to understand the structure and functioning of nature.
Computer techniques have been employed to address ecological problems related to the structures of communities and ecosystems. This involves using simulated models that can be descriptive or predictive. This branch of ecology is known as “systems ecology.”
Environmentalism emerged in the 1960s as a movement for environmental protection. At the international level, Greenpeace, founded in 1972 following a meeting in Vancouver, Canada, in 1971, stands out. Environmentalists recognize the disconnect between humans and nature caused by industrial civilization.
Industries inevitably deplete non-renewable resources, accumulate sources of pollution, and endanger the survival of species. In contrast, environmentalists advocate for balanced forms of development that are harmonious with nature, relying solely on clean, renewable energy sources.
Developing Ideas and Policies for Healthy Growth
In developing countries, the supply of sufficient food can be unreliable. Traditional agriculture struggles to support a growing population on limited land. Soil fertility is achieved through land fallowing, which allows nutrients to regenerate naturally. However, population growth makes this practice challenging, leading to declining fertility, soil erosion, and desertification.
Therefore, it is recommended that governments conduct an inventory of resources (soil, vegetation, fauna, rivers) and implement a rational combination of technology, decentralization of industry, and urban development in less populated areas.
Achieving these goals will be easier if governments exercise effective control over resources. Another significant challenge faced by developing countries is the lack of capital. Some industries utilize modern processes that minimize pollution, but these often require substantial capital investments.
The American Council on Environmental Quality estimates that industries need to invest four to five billion dollars annually in new “pollution-free” technologies. Additionally, a smaller but still significant investment, leading to a 5-10% increase in costs, is necessary to eliminate existing pollution and maintain cleanliness in the future.
The UN Conference on Development and Environment
The Earth Summit, also known as the ’92 ECO Summit or Rio Summit, organized by the UN, commenced on June 3, 1992, in Rio de Janeiro, Brazil. This meeting was held to commemorate the 20th anniversary of the Stockholm Conference. It brought together nearly 15,000 environmentalists, 100 heads of state, delegations from 170 countries, 50 international teams, and representatives from chemical, pharmaceutical, food, and other industries. It is evident that environmental protection is not the responsibility of a single nation or group of nations but a shared duty for all developed and developing countries.
Humanity has come to realize that the planet’s resources are not renewable in the short term and that every action taken on Earth, however small it may seem, has global repercussions. Initially, there were two distinct perspectives: that of developing countries and that of developed countries. Developing countries believe that environmental concerns must address two aspects: ensuring basic conditions for a dignified life and promoting a healthy quality of life. In contrast, developed countries, having already achieved basic living standards, can now focus on enhancing the quality of life.
The “greenhouse effect” is a fundamental global problem, causing an increase in the average global temperature. This could lead to the melting of the polar ice caps. Some developed countries are making progress in addressing their environmental problems, but at the expense of relocating their industries and toxic waste to poorer countries.
Since the Stockholm Conference twenty years ago, some problems have worsened, such as acid rain. There have been severe nuclear accidents (Chernobyl), industrial disasters (Seveso, Bhopal, Guadalajara), and numerous oil well fires during the Gulf War.
The Earth Summit aimed to sign two treaties that would benefit from funding. One treaty focuses on limiting greenhouse gas emissions, although it does not specify deadlines or amounts due to demands from the United States, a position supported by Argentina. The other treaty addresses the protection of genetic resources, which would primarily benefit developed countries as it allows them to utilize wild species from developing countries.
The summit also sought to implement the protocol signed in Montreal in 1987, which called for a 50% reduction in the use of chlorofluorocarbons by the end of the century to protect the ozone layer and control ocean pollution. These issues primarily concern developed countries, while developing countries prioritize poverty, sanitation, and the development of clean industries.
These problems were to be considered in the “Earth Charter,” but it did not receive initial support.
3. Water Pollution
Natural sources of water include rainwater, rivers, lakes, oceans, and groundwater. Water is found in many rocks and stones and in the atmosphere as clouds or mist.
Humans have always disposed of waste into water bodies. Under normal conditions, rivers can self-purify: water carries waste into the oceans, bacteria utilize dissolved oxygen to degrade organic compounds, and fish and aquatic plants consume these compounds, releasing oxygen and carbon back into the biosphere.
However, as human populations and industries have grown, this natural purification process has become increasingly strained. Concentrated industries and large populations can overload water systems with waste and industrial byproducts that cannot be effectively degraded by bacteria. This leads to a significant decrease in oxygen levels, rendering the river unable to support life and turning it into a polluted waterway. The risk is higher in slow-moving rivers, such as the Riachuelo.
Another threat is thermal pollution. Large power plants use water for cooling, raising the temperature of river water and disrupting biological processes, ultimately harming aquatic life.
Water is essential for human consumption, highlighting the need for improved hygiene. However, pollution reduces the quantity and quality of available water, making it challenging to meet these requirements.
Drinking water must be completely clean, tasteless, odorless, colorless, and have an approximate temperature of 15°C. It should be free from bacteria, viruses, parasites, and other pathogens that cause diseases. Achieving this level of water quality requires various purification processes.
Pure water is a renewable resource, but human activities can contaminate it to the point where it becomes harmful rather than beneficial.
What Pollutes Water?
- Pathogens: Bacteria, viruses, protozoa, and parasites that enter water from organic waste.
- Oxygen-demanding wastes: Organic wastes that can be decomposed by bacteria using oxygen. Large populations of these bacteria can deplete oxygen levels, harming aquatic life.
- Inorganic chemicals: Compounds of toxic metals (mercury, lead) that poison water.
- Plant nutrients: Can cause excessive growth of aquatic plants, which then die and decompose, depleting oxygen and harming marine life (eutrophication).
- Organic chemicals: Oil, plastics, pesticides, and detergents that threaten aquatic life.
- Sediment or suspended material: Insoluble soil particles that cloud water and are a major source of pollution.
- Radioactive substances: Can cause birth defects and cancer.
- Heat: Discharge of hot water that lowers oxygen content and makes aquatic organisms vulnerable.
Point and Nonpoint Sources
- Point sources: Discharge pollutants at specific locations through pipes and culverts (e.g., factories, sewage treatment plants, mines, oil wells).
- Nonpoint sources: Large areas of land that discharge pollutants over a wide area (e.g., chemical spills, agricultural land, livestock grazing, construction sites, septic tanks).
Pollution of Rivers and Lakes
Fast-flowing streams can recover relatively quickly from excess degradable waste and heat. However, this ability is compromised when pollutants overload the system or when water flow is reduced due to drought or dam construction.
Organic pollution: In lakes, reservoirs, estuaries, and seas, dilution is less effective than in streams due to limited water movement. This makes these water bodies more susceptible to pollution by plant nutrients (nitrates and phosphates), leading to eutrophication.
Control of Eutrophication by Crops
Prevention Methods:
- Advanced treatment to remove phosphates from industrial waste and sewage treatment plants before discharge.
- Prohibiting or limiting the use of low-phosphate detergents.
- Encouraging farmers to plant trees between their fields and surface waters.
Cleaning Methods:
- Dredging sediments to remove excess nutrients.
- Removing excess vegetation.
- Controlling the growth of noxious weeds with herbicides and pesticides.
- Using air pumps to oxygenate lakes and reservoirs.
As with other forms of pollution, prevention methods are more effective and cost-efficient in the long run.
Thermal Pollution of Streams and Lakes
The most common method for cooling steam in thermal power plants involves drawing cold water from a nearby surface water body, passing it through the plant’s condensers, and returning the heated water to the same source. High temperatures reduce the amount of dissolved oxygen in water. Fish adapted to a specific temperature range can die from thermal shock (sudden changes in water temperature).
The opposite of thermal pollution is thermal enrichment, which involves using heated water to extend fishing seasons, reduce ice cover in cold regions, heat buildings, etc.
Reduction of Thermal Water Pollution
- Reduce electricity consumption and waste.
- Limit the number of power plants discharging warm water into the same water body.
- Discharge warm water at a point far from environmentally sensitive areas.
- Use cooling towers to transfer heat from water to the atmosphere.
- Discharge warm water into ponds for cooling and reuse.
Oil Pollution
Oil pollution can result from tanker accidents, leaks at sea (oil escaping from drilled holes in the seabed), and waste oil dumped on land that eventually reaches the ocean through streams.
Effects of Oil Pollution
The effects of oil pollution depend on several factors, including the type of oil (crude or refined), the quantity released, the location of the spill, the distance from the shore, the season, water temperature, climate, and ocean currents. Oil that reaches the sea either evaporates or is slowly broken down by bacteria. Volatile organic hydrocarbons in oil can immediately kill marine animals, especially larvae.
Other chemicals remain on the surface, forming floating bubbles that coat the feathers of diving birds, destroying their natural insulation and causing them to drown. Heavy oil components that sink to the seabed can kill bottom-dwelling organisms like crabs and oysters or make them unfit for human consumption.
Marine Pollution Control in Petroleum
Prevention Methods:
- Reduce oil consumption and waste.
- Collect waste oil from vehicles and reprocess it for reuse.
- Prohibit oil drilling and transportation in ecologically sensitive areas and their vicinity.
- Increase the financial responsibility of oil companies for cleaning up spills.
- Require oil companies to routinely test their employees.
- Strictly regulate the safety and operational procedures of refineries and plants.
Cleaning Methods:
- Treat spilled oil with dispersant chemicals sprayed from aircraft.
- Use helicopters equipped with lasers to burn volatile oil components.
- Employ mechanical barriers to prevent oil from reaching the shore.
- Pump the oil-water mixture onto small boats called “skimmers,” where specialized machines separate the oil from the water and pump the oil into storage tanks.
- Increase government scrutiny of oil companies regarding oil spill containment and cleanup methods.
Contamination of Groundwater and Its Control
Surface water and groundwater are vital sources of water for drinking and irrigation. However, they are easily depleted because they are renewed very slowly. When contaminants reach groundwater, it cannot purify itself as effectively as surface water due to slow flow rates and limited oxygen, which hinders bacterial degradation.
Because groundwater is not visible, there is often less awareness of its importance.
Sources of Groundwater Pollution
- Leaks or spills from underground storage tanks.
- Infiltration of organic chemicals and toxic compounds from landfills, abandoned dumps, and hazardous waste ponds located above or near aquifers.
- Accidental infiltration into aquifers from injection wells used to dispose of hazardous waste deep underground.
Prevention Methods:
- Prohibit the disposal of hazardous waste in landfills and by deep well injection.
- Monitor aquifers.
- Implement stricter controls on the application of pesticides and fertilizers.
- Require annual water quality testing for private wells used for drinking water.
Pollution Control of Surface Water
Nonpoint source pollution:
Agriculture is a major source of nonpoint water pollution. Farmers can significantly reduce fertilizer runoff into surface water and infiltration into aquifers by avoiding excessive fertilizer application. They should also minimize pesticide use.
Pollution Sources: Wastewater Treatment
In many less developed countries and some parts of more developed countries, sewage and industrial waste are not treated. Instead, they are discharged into the nearest waterway or waste lagoons, where air, sunlight, and microorganisms degrade the waste. The water remains in these lagoons for about 30 days. It is then treated with chlorine and pumped for use in towns or on farms. In more developed countries, most point source waste is treated to varying degrees. In rural and suburban areas, sewage from individual houses is typically discharged into septic tanks.
In urban areas of more developed countries, most wastewater from homes, businesses, factories, and rainfall runoff flows through a network of sewer pipes to wastewater treatment plants. Some cities have separate systems for stormwater runoff, but in others, the pipes for both systems are combined for cost savings. During heavy rains, combined sewer systems can overflow, discharging untreated sewage directly into surface waters.
Wastewater reaching a treatment plant can undergo up to three levels of purification. Primary sewage treatment is a mechanical process that removes debris such as sticks, stones, and rags.
Secondary sewage treatment is a biological process that utilizes aerobic bacteria.
Advanced wastewater treatment involves a series of specialized physical and chemical processes that reduce the amount of specific contaminants remaining after primary and secondary treatment.
Before being discharged from a treatment plant, wastewater is disinfected, typically using chlorine. Other disinfectants include ozone, hydrogen peroxide, and ultraviolet light. Conventional sewage treatment has helped reduce surface water pollution, but environmentalists argue that it is a limited and imperfect approach that will eventually be overwhelmed as populations grow and generate more waste.
Land Disposal of Sewage Effluent and Sludge
Sewage treatment produces a viscous, toxic sludge that must be disposed of or recycled as fertilizer. Before application as fertilizer, the sludge must be heated to kill harmful bacteria.
Protection of Coastal Waters
Prevention Methods:
- Eliminate the discharge of toxic pollutants into coastal waters.
- Use separate disposal systems for stormwater and sewage.
- Reduce water consumption and waste.
- Prohibit the disposal of sediment from sewage and hazardous dredging materials into the sea.
- Protect pristine coastal areas.
- Reduce reliance on oil.
- Implement methods to prevent oil pollution.
- Prohibit the disposal of plastic and garbage from ships.
Cleaning Methods:
- Significantly improve the capacity to clean up oil spills.
- Upgrade all coastal sewage treatment plants.
4. Marine Pollution
Marine pollution is defined as:
“The introduction by man, directly or indirectly, of substances or energy into the marine environment, resulting in such deleterious effects as harm to living resources, hazards to human health, hindrance to marine activities, including fishing and other legitimate uses of the sea, impairment of quality for use of seawater and reduction of amenities.”
The key to this definition is the phrase “introduction by man.” Some pollution is deliberately discharged into the oceans, while other pollutants reach the sea indirectly through rivers.
When river water enters the sea, it carries with it the consequences of river pollution, causing fish poisoning and a decline in coastal fisheries production due to high fish mortality.
The sea is also contaminated by oil spills from tankers, releasing highly polluting substances into the ocean. Hydrocarbons, being immiscible with water, float on the surface in layers of varying thickness, carried by ocean currents. Some of the oil dissolves, while the rest pollutes beaches.
Humans have engaged in maritime activities and fishing since ancient times, but it is essential to avoid overexploitation to prevent the extinction of marine life.
Humans utilize the sea for trade, fishing, recreation, extraction of chemicals, and disposal of increasing amounts of various types of waste. For example, oil tankers are sometimes cleaned at sea to avoid delays at ports, contaminating the sea surface and, through currents, coastlines. This practice has resulted in the deaths of penguins and whales off the coast of Argentina.
Ocean Pollution
The ocean has become the “world’s garbage dump,” which will have detrimental consequences in the future. Most of the world’s coastal areas are polluted, primarily due to sewage discharge, chemicals, garbage, radioactive waste, oil, and sediment. The most polluted seas are in Bangladesh, India, Pakistan, Indonesia, Malaysia, Thailand, and the Philippines.
Dolphins, sea lions, and sea turtles die when they ingest or become entangled in cups, bags, ropes, and other plastic debris dumped into the sea.
5. Conclusion
The human population is growing exponentially, leading to increasing demand for food and basic necessities. This requires more energy, raw materials, finished products, and waste, often containing toxic substances. These factors have caused significant changes on Earth: entire regions in tropical areas have become deserts, plant and animal species have become extinct, and others are endangered.
Humans exploit natural resources as if they were infinite, dumping finished products and waste materials on land, in water, and recently even in the open ocean, as if these environments can absorb them without suffering any consequences.
Another serious problem is the growth of large cities in both developing and developed countries, which approach environmental issues from different perspectives based on their own interests. These cities contribute to networks of changes that alter natural and cultural landscapes.
All these changes also affect the human psyche, which requires green spaces for relaxation.
An optimal quality of life necessitates maintaining the balance of nature. Humans must learn that the environment is not something to be manipulated at will but rather a system to be integrated with for a better life.
A crucial step towards improving our habitat would be for humans to change their attitude towards the environment, embracing internal values and respecting its rights.