Environmental Pollution and It's Effects on Crop and Humans | Agriculture Optional Notes for UPSC PDF Download

Environmental Pollution

Environmental pollution can be defined as the introduction of undesirable substances into the environment as a result of human activities. These substances, known as pollutants, can be in the form of chemicals, biological agents, or physical materials that are released into the environment, either intentionally or unintentionally. They have the potential to cause harm, directly or indirectly, to humans and other living organisms.

Types of Environmental Pollutants

• Primary pollutants are those that remain in the environment in their original form after being introduced, such as plastic and DDT.
• Secondary pollutants are formed through interactions between primary pollutants. An example of this is the combination of hydrocarbons and nitrogen oxides, which results in the creation of peroxyacetyl nitrate (PAN).

Nature of Existence

• Quantitative pollutants are substances that occur naturally but become pollutants when their concentration exceeds a certain threshold. Examples include nitrogen oxide and carbon dioxide.
• Qualitative pollutants are artificial and do not exist in nature. Pesticides like herbicides, fungicides, and DDT fall into this category.

Disposal Nature

• Biodegradable pollutants are waste products that can be broken down by microbial action. An example is sewage.
• Non-biodegradable pollutants do not decompose due to microbial action and include items like glass, plastics, heavy metal salts, and toxic compounds.

Origin

• Nature
• Anthropogenic

Types of Environmental Pollution

Environmental pollution may be of the following types:

• Air pollution
• Noise pollution
• Water pollution
• Soil pollution
• Thermal Pollution
• Radiation pollution
• Air pollution

Air pollution

Air pollution is a form of environmental contamination characterized by the presence of various substances in the atmosphere, whether in gaseous, liquid, or solid form. This pollution encompasses noise and radioactive radiation when their concentrations are harmful to humans, other living organisms, property, and plants.
Additionally, it disrupts regular environmental processes. Airborne pollutants come in two primary categories:

• Suspended Particulate Matter:
  • These particulate pollutants can vary in composition and often result in reduced sunlight and visibility.
  • Health consequences may include conditions like pneumoconiosis, cancer, asthma, and other lung diseases.
  • Fly ash, for instance, can settle on vegetation and buildings, increasing the levels of suspended particulate matter in the air and potentially leading to the presence of hazardous substances in leachates.
• Gaseous Air Pollutants:
  • Gaseous pollutants, such as carbon monoxide (CO), carbon dioxide (CO₂), sulfur compounds (SO₂ and H₂S), nitrogen compounds (NO and N₂O), hydrocarbons like benzene and ethylene, lead, and ozone, arise from various sources, including the incomplete combustion of carbon-based fuels, industrial processes, vehicle emissions, and natural events such as volcanic eruptions.
  • For example, carbon monoxide is produced from incomplete burning of fuels like gasoline, diesel, and wood, while carbon dioxide is generated from the burning of coal, oil, and natural gases.

Water Pollution

• Water pollution is the result of introducing various substances into water, including inorganic, biological, organic, radiological, and thermal pollutants, which compromise the quality of water, making it unsuitable for human consumption. This pollution is a significant and pressing environmental concern with visible consequences in various areas.
• The effects of water pollution are widespread and stem from human activities, including agriculture, industry, and domestic practices. For instance, pollutants like unnecessary pesticides and fertilizers in agricultural runoff, harmful chemicals in industrial wastewater, and sewage contaminated with human and animal waste are among the contributors to water pollution.
• Natural causes of water contamination include soil erosion, mineral leaching from rocks, and the breakdown of organic matter. Pollution can affect a wide range of water bodies, including oceans, rivers, estuaries, lakes, and groundwater sources.
• Water pollution can originate from specific and diffuse sources. Point source pollution arises when pollutants are released from identifiable locations, such as industrial effluents discharged directly into a water body via a drainpipe. Nonpoint sources, on the other hand, involve pollution coming from dispersed sources over a broader area, like runoff from farmlands, pastures, construction sites, abandoned mines, landfills, and roadways.

Sources of Water Pollution: Sources of water pollution can be categorized into two main types: point sources and diffuse or nonpoint sources.

1. Point Sources: These are directly traceable to a specific and identifiable influence. Pollutants from point sources travel from the source to the water body, and they are relatively easy to regulate.

2. Diffuse or Nonpoint Sources: Diffuse sources originate from a variety of poorly defined and vague sources, making them challenging to monitor due to spatial and temporal variations.
The following are primary sources of water pollution:

• Community Wastewater: This includes discharges from residential, commercial, and industrial facilities connected to the public sewerage system. Sewage contains various waste components, including food residues, human and animal excreta, detergents, cleaning agents, and more.
• Industrial Wastes: Industries release both inorganic and organic contaminants that can have detrimental effects on living organisms.
• Agricultural Sources: Fertilizers, rich in nutrients like phosphorus, nitrogen, and potassium, are commonly used in agriculture. Excess fertilizers can leach into groundwater or mix with surface water through drainage and runoff.
• Pesticides: Pesticides include fungicides, insecticides, herbicides, rodenticides, nematicides, and soil fumigants. These substances contain various chemicals, some of which are non-biodegradable and can persist in the environment for extended periods.
• Animal Excreta: During the rainy season, animal waste, such as urine and dung from farms like piggeries, poultry farms, and slaughterhouses, can enter water bodies through runoff and surface leaching.
• Thermal Pollution: Thermal and nuclear power stations are significant sources of thermal pollution. These facilities use water as a coolant, and when heated water is returned to the source, abrupt temperature changes can harm aquatic life.
• Groundwater Pollution: Groundwater, a vital source for residential, drinking, agricultural, and commercial purposes worldwide, can become contaminated due to human activities. Factors like farmyard dumping, excessive waste disposal, agricultural chemicals, and industrial effluents contribute to groundwater pollution.
• Marine Pollution: Oceans serve as major sinks for various pollutants, both natural and man-made. Rivers discharge pollutants into the sea, and coastal cities may pump sewage and waste into the ocean. Additional sources of marine pollution include grease, navigational discharges of tar, sewage, detergents, underwater oil mining, hazardous wastes, and oil spills.

Soil Pollution

Soil pollution, within the realm of environmental pollution, is characterized by the introduction of substances into the soil that adversely affect its chemical, biological, and physical properties, ultimately harming its productivity.

Sources of Soil Pollution: Soil pollution has various sources, including:

• Plastic Bags: Plastic bags, especially those made of low-density polyethylene (LDPE), pose significant environmental risks as they are nearly indestructible and non-biodegradable. They persist in the soil, continually releasing toxic substances.
• Industrial Sources: Industrial activities contribute to soil pollution through chemical residues, fly ash, metallic and nuclear waste disposal. Harmful substances like dyes, synthetic chemicals, and acids can find their way into the soil.
• Agricultural Sources: Soil contamination from agricultural sources is often linked to the use of chemical fertilizers and pesticides. Excessive application of these chemicals can reduce the population of soil-borne species, alter the soil's structure, reduce fertility, and increase salt content.
• Radioactive Wastes: Radioactive elements enter the soil from nuclear power plants and mining operations, posing a risk to soil quality.
• Other Pollutants: Air pollutants and water contaminants can also make their way into the soil. Additionally, certain harmful chemicals are released into the ground during the weathering of specific types of rocks.

Noise Pollution

Noise pollution is characterized as "any undesired sound experienced by the recipient," essentially signifying sound without value. It refers to unpleasant noise generated by human activities or machines that can be bothersome, disruptive, intrusive, and even physically discomforting. This form of environmental pollution is primarily caused by factors such as household appliances, road traffic, and transportation.

Sources of Noise Pollution: Noise pollution can originate from a variety of sources, including:

• Indoor Sources: These encompass sources of noise inside buildings and homes, such as engines, radios, electric fans, televisions, air conditioners, various household appliances, air coolers, and domestic disputes. Noise pollution from transportation is more prevalent in urban areas, given the higher concentration of factories, residents, and various activities.
• Outdoor Sources: Noise pollution in outdoor environments arises from activities such as the indiscriminate use of loudspeakers, industrial processes, automobiles, railway traffic, aircraft, as well as events like those in marketplaces, religious gatherings, social and cultural functions, sports events, and political rallies. In rural areas, farm machinery and pump sets are major contributors to noise pollution. Additionally, noise pollution is heightened by the use of fireworks during festivals, weddings, and other occasions.

Thermal Pollution

Thermal pollution is the alteration in temperature of a natural aquatic environment resulting from human activities. It can involve either an increase or decrease in the water temperature.

Sources of Thermal Pollution: Thermal pollution is mainly attributed to the following sources:

• Power Plants: Power plants and factories contribute to thermal pollution by discharging heated water into aquatic environments.
• Shoreline Deforestation: The removal of trees and vegetation along the shorelines can lead to increased water temperatures in streams, as it allows more sunlight to reach and warm the water.
• Water as a Cooling Agent: The release of cold water into a water body can have a cooling effect, which influences the water's temperature.

Radiation Pollution

Radiation, which is a form of energy that traverses through space, can lead to radiation pollution when human activities cause an increase in the natural radiation levels. Approximately 20% of the radiation exposure humans experience is attributable to these activities.
One of the most significant contributors to radiation pollution is the radiation emitted from the decay of radioactive nuclides.
Radiations are categorized into two groups:

• Non-Ionizing Radiations: These include short-wave radiations like ultraviolet rays from the sun. They have limited penetrating ability and impact the cells and molecules they encounter.
• Ionizing Radiations: Examples of ionizing radiations are X-rays, gamma rays, and atomic radiations generated by radioactive elements. They possess a high penetration power and can cause the breaking of macromolecules.

Different types of radiation particles include:

• Alpha Particles: These can be blocked by a sheet of paper and human skin.
• Beta Particles: They can pass through the skin but are halted by materials like glass and metal.
• Gamma Rays: Gamma rays are highly penetrating and can quickly pass through human skin, potentially damaging cells along the way. They can only be effectively stopped by thick, solid, massive structures like concrete.

The sources of radiation pollution can be categorized into natural and man-made sources:

• Natural Sources: Cosmic rays from space and terrestrial radiations arising from naturally occurring radionuclides found in the Earth's crust, including uranium-238, radium-224, potassium-40, thorium-232, carbon-14, and more.
• Man-Made Sources: These include activities related to nuclear power plants (such as the nuclear reactor accident at Chernobyl in 1986), nuclear weapons (e.g., atomic explosions in Nagasaki and Hiroshima), transportation of atomic materials, nuclear waste disposal, uranium mining, and radiation therapy.

Light pollution

Light pollution refers to the presence of artificial and human-made light in the nighttime environment. When there is an excess of light that falls on the retina, it can cause significant discomfort to the eyes. This problem is exacerbated by the excessive, misdirected, or intrusive use of artificial light, and even when used carefully, it still fundamentally alters natural conditions.

Effects of Light Pollution: Light pollution has several adverse effects, including:

• Disruption of Animal Reproductive Cycles: It disturbs the reproductive cycles of certain animals and contributes to a loss of biodiversity. This is due to changes in predation and migration patterns of wildlife.
• Impact on Human Circadian Rhythms: In humans, light pollution disrupts circadian rhythms, which regulate hormones and other bodily functions, leading to behavioral changes and psychological effects.
• Sleep Disturbance: The excessive blue light emitted by LEDs directly affects human sleep patterns by suppressing the production of the hormone melatonin, which plays a role in the sleep-wake cycle.
• Impact on Nocturnal Species: Over 30 percent of vertebrates and more than 60 percent of invertebrates are nocturnal, and artificial light has a detrimental impact on these species. It also affects plants and microorganisms.

Nitrogen Pollution

• Nitrogen pollution results from the combustion of fossil fuels in automobile engines, where high temperatures cause the combination of dinitrogen and dioxygen to produce significant quantities of nitric oxide (NO) and nitrogen dioxide (NO₂) through chemical reactions. Specifically:
  • N₂ (g) + O₂ (g) → 2NO(g)
  • 2NO (g) + O₂ (g) → 2NO₂ (g)
• The production rate of NO2 is accelerated when nitric oxide reacts with ozone in the stratosphere:
  • NO (g) + O₃ (g) → NO₂ (g) + O₂ (g)
• This results in the formation of a reddish haze in traffic-congested areas due to the presence of nitrogen oxides. Elevated concentrations of NO₂ can harm plant leaves and impede the rate of photosynthesis. Nitrogen dioxide acts as a lung irritant, particularly impacting children, and can be toxic to living tissues, textile fibers, and metals.
• Nitrogen compounds from farmland runoff have led to water pollution problems globally, while emissions of nitrogen from industry, agriculture, and vehicles significantly contribute to air pollution. Nitrogen becomes a pollutant when it escapes into the environment and reacts with other organic compounds. It can be released into the atmosphere, dissolved in water sources such as rivers, lakes, or groundwater, or remain in the soil. While nitrogen can support the growth of certain species, its presence as a pollutant is often detrimental to the environment and human health.

Conclusion

In summary, environmental pollution can be defined as the contamination of the physical and biological components of the Earth and its atmosphere to an extent that it has adverse effects on the natural environmental processes.