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The Main Causes of Water Pollution

Water pollution is any contamination of water by chemicals or other substances which are harmful to human, plant, or animal wellbeing. These pollutants include pesticides and fertilizers in agricultural runoff, sewage and food processing waste, lead, mercury, along with a list of other heavy metals, chemical wastes from industrial discharges, and chemical pollution from toxic waste sites. Almost 2 billion people worldwide consume polluted water that is detrimental to their health.

There are various sources of pollutants, but they boil down to two categories: point and nonpoint sources. Point sources (localized contamination) are where pollutants come from a single, recognizable source. Nonpoint sources come from dispersed and often hard to pinpoint sources. Point sources of water pollution are generally simpler to control than nonpoint sources because the polluted water was collected and hauled to a point where it could be treated. Pollution from sources that are dispersed are harder to restrain and cause a huge portion of water pollution issues.

Water Pollution By Pesticides

pesticides sprayed on crops seeps into groundwater
pesticides being sprayed on crops seeps into groundwater
Photo by Wuzefe

The word “pesticide” is really a joint term that comprises all substances that are utilized to kill or control any manner of pests. This includes herbicides (weeds), insecticides (insects), fungicides (fungi), nematocides (nematodes), and rodenticides (vertebrate poisons). Pesticides play an important part in food manufacturing by increasing harvests and also the amount of times a crop could be grown on the land per year.

As groundwater is used for drinking water from about 50% of the national population, pesticidal pollution of groundwater is a topic of great significance. Individuals living in agricultural areas where pesticides are used the most should be particularly concerned by this, as about 95% of that population is dependent upon groundwater for drinking water. Before the mid-1970s, it had been believed that soil functioned as a filter for pesticides. Studies have shown that this isn’t true. Pesticides still reach aquifers from crop areas through seepage and improper disposal.

Farmland is well drained and is frequently enhanced through mechanical means. Soil can’t always store the amount of water from irrigation and rainfall. Therefore, pesticides may be transported to pollute groundwater and freshwater reserves.

Water Pollution by Sewage Waste

city sewage drains into larger bodies of water
city sewage drains into larger bodies of water
Photo by Grzegorz_Skibka

Sewage is the main source of microorganisms and decaying organic materials. All town and city sewage contains germs and pathogens of some kind, presenting a danger to public health. Decaying matter poses a different type of danger to water supplies. As bacteria and other germs decompose organic sewage, the oxygen content of the water is depleted. The oxygen depleted waters lower the quality of water needed for fish and other aquatic species to flourish when it reaches lakes and streams. Sewage treatment procedures reduce the amount of bacteria and germs but don’t completely remove them.

Sewage is a primary source of plant nutrients. An overflow of nitrates and phosphates in water foster the development of algae causing algal blooms. Because bacteria utilize oxygen to digest algae when they die, oxygen levels decrease. Anaerobic organisms (organisms which don’t need oxygen to survive) then digest the organic wastes, discharging gases like methane and hydrogen sulfide which are harmful for the aerobic (oxygen-requiring) organisms. The process in which a pond changes from a clean, clear state -with a comparatively low concentration of dissolved nutrients and a balanced aquatic community-into a nutrient-rich, algae-filled and therefore an oxygen-deficient state is known as eutrophication. Eutrophication is a naturally occurring procedure. But when it’s sped up by water pollution, it may result in the premature death of a body of water.

Heavy Metal Pollution

Mining is the most common cause of heavy metal pollution in water
Mining is the most common cause of heavy metal pollution in water
Photo by darkmoon1968

Heavy metals are naturally occurring elements that have a density of at least 5 times greater than that of water. Their domestic, industrial, medical, technological, and agricultural uses raise concerns over their possible consequences on the environment and human health.

Heavy metals are dangerous because they tend to bioaccumulate. Bioaccumulation is an increase in the concentration of a compound in a biological organism over time. Compounds accumulate in living things whenever they are consumed and stored faster than they can be metabolized.

Metals are introduced in aquatic systems in natural ways, but also from many different human activities. The most frequent heavy metal pollutants include arsenic, cadmium, chromium, copper, nickel, lead, and mercury.

Water pollution from metals most commonly stems from the mining businesses. They often use an acid mine drainage system to release heavy metals from ores, since metals are soluble in an acid solution. Following the drainage procedure, they dilute the acid solution in groundwater, contaminating it with elevated levels of metals.

Industrial Waste

Industrial waste being dumped into a river
Industrial waste being dumped into a river

There is a lack of strict pollution management policies, particularly in underdeveloped and developing countries around the world. The indifference of law enforcement authorities has allowed industries to not take laws seriously and bypass them pretty easily.

Industrial water pollution can have many detrimental effects on the ecosystem. The water used in various industrial processes such as cleaning comes in contact with poisonous substances, heavy metals, organic sludge, as well as radioactive sludge. Therefore, when that contaminated water is disposed into the ocean or rivers, they become unfit to support life.

Thermal Pollution

Nuclear plants use river water for cooling
Nuclear plants use river water for cooling
Photo by Frédéric Paulussen on Unsplash

Thermal pollution is defined as a sudden increase or reduction in temperatures, from human influence, of a natural body of water. It can have an adverse effect on marine life, as a few organisms are sensitive to fluctuations in temperatures. This normally occurs when a plant or facility takes water from a river or other body of water to use it as a cooling method for machinery and returns it with an altered temperature.

Nuclear reactors and power plants are also a major source of thermal and water pollution. Radioactive sludge deposited at the base of water bodies could remain radioactive for decades and pose severe health hazards to people living nearby.

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