pollution of the natural environment

pollution of the natural environment Pollution alters the natural environment, adversely affecting its use by ‘environmental receptors’ such as plants, animals, and humans. The natural environment includes three environmental media: air, land, and water. Water includes surface water (wetlands, rivers, lakes and oceans) and groundwater aquifers which flow underground. Pollution contaminates these environmental media, which may then serve as pathways that transfer contaminants to other media or to receptors. For example, industrial waste disposed in landfills may contain contaminants such as solvents, metals, or pesticides that leach through soils to underlying groundwater. The contaminated groundwater might then be used as a human drinking water source or might discharge to a surface water body, adversely influencing aquatic life or humans using the water for recreational purposes.

Some natural events can be pollution sources. For example, volcanic eruptions and forest fires emit harmful gases and particulate matter to the air. The contaminated air is harmful to plants, animals, and humans. In addition, volcanic ash carried through the air and deposited on the land in large quantities adversely affects plant growth and agriculture in the short term. In certain circumstances animals can cause pollution. For example, manure in large concentrations can pollute surface water quality by increasing the organic loading of a water body (see below). This loading reduces dissolved oxygen levels in the water.

The term ‘environmental pollution’ is, however, more often used to describe the direct or indirect impacts of human activities. The cumulative effects of concentrated human activities can create large-scale or long-term environmental consequences beyond the assimilative capacity of the environment. Land, water, air, and other types of pollution such as radiation, noise, and visual pollution are some direct results of human activities. Indirect pollution like global warming and ozone depletion in the atmosphere are also occurring. Indirect effects are more difficult to prove because they can occur over long periods of time and result from complex chemical and atmospheric reactions. Indirect pollution is the subject of important environmental research.

Water pollution

Pollutants of concern for water include (1) pathogenic organisms and organic matter present in human, animal, medical, and food-processing wastes and (2) chemicals, particulates, and heavy metals present in industrial discharges or associated with soil erosion. Organic wastes are often oxygen-demanding and decrease the dissolved oxygen content of water. Plants and animals in the water rely on this oxygen and are adversely affected by its absence. Bacteria present in organic matter can have adverse effects on human and animal health. Thermal pollution consists of excess heat contained in water discharged from industrial cooling plants or processes. It can increase the temperature of water bodies and also decrease their available oxygen content. Erosion consequent on agriculture, deforestation, construction, or mining operations can deposit particulates like soil into water bodies. Although these particulates may not be inherently toxic, they can impede water flow or completely fill a water body.

Storm water run-off from roads, industrial units, farms, and construction sites also has significant potential for causing water pollution. Contaminated storm-water run-off can contain oil, chemicals, animal waste, and particulates that are transported over land or through drainage systems into surface water bodies. Groundwater pollution generally results from contaminants leaching through soils to underlying aquifers. For example, landfills and underground storage tanks may release contaminants to underground aquifers. These aquifers might then discharge contaminated groundwater to surface water bodies. In rural areas, groundwater pollution poses a significant cause of concern for residents who rely on wells for their drinking-water supplies.

Air pollution

Air pollution includes materials released to the atmosphere that alter the constituents or the ratio of constituents found in normal dry atmospheric air. Types of air pollution include particulate and gaseous emissions and odour pollution. Particulates include dispersed airborne solid and liquid particles larger than single molecules. Particulates are often present in dust, fumes, smoke, mists, and sprays. Gaseous pollutants include wastes or emissions that are gaseous at normal atmospheric temperatures and pressures. These pollutants include ozone, sulphides, nitrogen oxides, carbon monoxide, hydrocarbons, and sulphur oxides. Air emissions can include metal particles, asbestos fibres, or volatile organic compounds.

Land pollution

Land pollution results from a variety of sources, including spills of industrial and household materials and air transport of contaminants deposited on land. For example, lead dust generated from industrial operations can be deposited on land, posing a health hazard to animals or humans through ingestion or inhalation.

A primary cause of land pollution is waste disposal. Open dumps or tips are still used in many parts of the world and pose a risk of disease transmission to humans and animals through pests living on the dump and pathogens or chemicals present in exposed waste. Open dumps are also sources of odour and air-emission pollution. They can contaminate underlying soils and groundwater or contaminate storm water which travels to bodies of surface water.

Because of the problems associated with open dumps, some countries require waste disposal in landfills. Modern landfills incorporate controls to prevent pollution of the environment. For example, they are built in areas where the geology can be expected to reduce potential migration of pollution. They are also equipped with clay or synthetic liners to prevent release of contaminants to soil and groundwater. The waste is compacted and covered regularly to control pest populations and prevent human contact and air releases. Experience has shown, however, that in time contaminants may still leach to underlying soils and groundwater as a result of liner leaks, improper design, or water infiltration. When releases occur, pollution results.

Odour pollution is often associated with air pollution. Examples include strong odours emanating from industrial facilities like paper mills, concentrated vehicle emissions, farms and food-processing facilities, and inadequate sewage facilities.

Air pollution can pose health hazards and damage plant life over time. Humans and animals may breathe contaminated air or ingest plants coated with pollutant deposits. Air pollution can result indirectly from air emission. For example, photochemical smog indirectly results from industrial and vehicle emissions, through chemical reactions occurring in the atmosphere. Similarly, sulphur dioxide emissions from coal- and oil-fired power plants can interact with water molecules present in the air to form acid rain. Acid rain is a threat to plant life and can damage exposed statues and buildings as well.

Other types of pollution

Radiation is generated by the nuclear power industry, medical activities (for example, X-rays), and nuclear weapons production. If it is not properly contained, radiation pollution will occur and affect environmental media and receptors. Large doses of radiation pollution can damage plant and animal life. Radiation might increase cancer risks, and might be associated with genetic mutations. Noise pollution generated by airports, traffic, loud music, construction, and industry can be a nuisance and permanently impair hearing over time. Visual pollution includes billboards, rubbish dumps, and other man-made structures that destroy the beauty of a landscape. Noise, visual, and odour pollution are sometimes evaluated subjectively. One person may consider a piece of music to be art while another considers it noise pollution. One person may enjoy a billboard while another considers it a visual insult.

C. Buriks