The Major Effects of Water Pollution
Virtually all types of pollution are harmful to the health of humans and animals. Pollution may not damage our health immediately but can be harmful after long term exposure. Different forms of pollutants affect the health of animals in different ways.
Water Pollution Effects
Water pollution effects can be categorized namely:
Waterborne Infectious Diseases
Human infectious diseases are among the most serious effects of water pollution, especially in developing countries, where sanitation may be inadequate or non-existent.
Waterborne diseases occur when parasites or other disease-causing microorganisms are transmitted via contaminated water, particularly water contaminated by pathogens originating from excreta.
These include typhoid, intestinal parasites, and most of the enteric and diarrheal diseases caused by bacteria, parasites, and viruses. Amongst the most serious parasitic diseases are amoebiasis, giardiasis, ascariasis, and hookworm.
Every year there are thousands of beach closings worldwide, and outdated monitoring methods may in some cases leave beachgoers vulnerable to a range of illnesses. Polluted beach water can cause rashes, earaches, pink eye, respiratory infections, hepatitis, encephalitis, gastroenteritis, diarrhea, vomiting, and stomach aches.
The Woods Hole Oceanographic Institution calls nutrient pollution the most widespread, chronic environmental problem in the coastal ocean. The discharges of nitrogen, phosphorus, and other nutrients comes from agriculture, waste disposal, coastal development, and fossil fuel use.
Once nutrient pollution reaches the coastal zone, it stimulates harmful overgrowths of algae, which can have direct toxic effects and ultimately result in low-oxygen conditions. Developed countries have started monitoring for toxic algal blooms, closing fisheries as necessary.
This has reduced the incidence of related human illness but has had the obvious economic cost of lost income for fishermen and related businesses.
Nutrient-pollution-driven blooms of non-toxic algae and seaweed can also cause problems by reducing water clarity, making it hard for marine animals to find food and blocking the sunlight needed by sea grasses, which serve as nurseries for many important fish species.
When the algal overgrowths finally die, they sink to the bottom and begin decomposing. This process uses oxygen from the surrounding water.
In some cases, the decomposition process takes enough oxygen out of the water that the level falls too low to support normal aquatic life and the region becomes a coastal dead zone. Finally, nutrient pollution can trigger unusual outbreaks of fish diseases.
Over the years, many types of chemicals have gotten into our waterways and they continue to do so today. Chemical water pollution typically occurs because:
The chemicals were dumped into the water intentionally;
The chemicals seeped into groundwater, streams, or rivers because of failing pipes or storage tanks;
The chemicals catastrophically contaminated waterways because of industrial accidents;
The pollution settled out of polluted air (or was precipitated out of polluted air); or
Chemicals were leached out of contaminated soil.
The above types of chemical contamination are considered “point sources” of water pollution. Non-point-source chemical pollution also occurs via pesticide runoffs from farm fields and homeowners’ lawns, as well as runoffs of automotive fluids and other chemicals from roads, parking lots, driveways, and other surfaces.
It’s beyond the scope of this course to document the effect of every chemical that has ever polluted water, but it’s easy enough to point out a few things:
Severe chemical spills and leaks into surface waters usually have an immediate effect on aquatic life (kills fishes, etc.).
Chronic lower-level chemical pollution has more subtle effects, with problems manifesting over a long period of time and sometimes being difficult to tie directly to the water pollution.
The human effects of chemical pollution in water can generally be viewed the same way as any other form of chemical contamination— water is just the delivery mechanism.
There are a few broad categories of water pollution effects related to chemicals that are worth exploring further, which we do below.
Read Also : The Eight (8) Main Types of Water Pollutants
Pesticides are carried in rainwater runoffs from farm fields, suburban lawns, or roadside embankments into the nearest creeks and streams.
Occasionally they are even intentionally sprayed into waterways as part of a pest-control effort.
Here are some noteworthy examples of the effects of pesticide water pollution:
Atrazine (the most commonly used herbicide in the US) causes feminization of male frogs even at concentrations in water as low as 0.1 parts per billion.
Atrazine water pollution has been noted in many countries, including South Africa, Germany, and Denmark.
Studies indicate the chemical may be linked to a number of human cancers, including prostate cancer and non-Hodgkin’s lymphoma, as well as hormonal problems that could disrupt reproductive and developmental processes.
Glyphosate (Roundup), another of the world’s most common herbicides, was found to cause a 70% decline in frog biodiversity and an 86% decline in the total mass of tadpoles when the glyphosate got into water.
Pesticides have been found in well water in countries such as India, The Netherlands, Italy, Israel, Japan, Canada and Australia. Pesticide contamination of drinking water is a perculiar problem in rural agricultural areas where pesticide use is heavy and drinking water supplies come directly from groundwater or surface water.
Pesticides can migrate via water into the food chain as well, ultimately being consumed by humans or animals in food.
In the most infamous case of pesticide pollution, widespread use of the insecticide DDT polluted waterways, contaminating fish, and ultimately poisoning bald eagles (and other animals) that ate the fish.
DDE, the principal breakdown product of DDT, built up in the fatty tissues of female eagles and prevented sufficient calcium being released to produce strong egg shells. The thin shells would break when the parents sat on the eggs to keep them warm. DDT affected many other species as well.
In terms of general human health effects, pesticides can affect and damage the nervous system;
Cause liver damage;
Damage DNA and cause a variety of cancers;
Cause reproductive and endocrine damage;
Cause other acutely toxic or chronic effects.
Oil and Petroleum Chemicals
When oil pollution gets in water, some of the components are degraded and dispersed by evaporation, photochemical reactions, or bacterial degradation, while others are more resistant and may persist for many years, especially in shallow waters with muddy sediments.
Though much scientific work remains to be done on the effect petroleum pollution has on plants and animals, we do know a few things: Exposure to oil or its constituent chemicals alter the ecology of aquatic habitats and the physiology of marine organisms.
Scientists know that oil (or chemical components of oil) can seep into marsh and sub-tidal sediments and lurk there for decades, negatively affecting marsh grasses, marine worms, and other aquatic life forms that live in, on, or near the sediment.
Evidence strongly suggests that components of crude oil, called polycyclic aromatic hydrocarbons (PAHs), persist in the marine environment for years and are toxic to marine life at concentrations in the low parts-per-billion range.
Chronic exposure to PAHs can affect development of marine organisms, increase susceptibility to disease, and jeopardize normal reproductive cycles in many marine species.
Mercury finds its way into water primarily through air pollution from coal-fired power plants and some other industrial processes.
In the water, the elemental mercury is converted to methylmercury by certain bacteria, after which it moves up the food chain of fish gobbling each other up. In the end, the larger fish may end up on your dinner plate— swordfish, sea bass, marlin, halibut, or tuna, for example.
The effects of mercury on humans are already pretty well understood. However, the more we learn, the worse the news gets.
Exposure to mercury in the womb can cause neurological problems, including slower reflexes, learning deficits, delayed or incomplete mental development, autism, and brain damage. Mercury in adults is also a problem, causing:
Central nervous system effects like Parkinson’s disease, multiple sclerosis, and Alzheimer’s disease;
Heart disease; and, in severe cases,
Causing death or irreversibly damaging areas of the brain.
Animals in any part of the food chain affected by the bioaccumulation of mercury can also suffer the effects of mercury pollution. Possible effects include death, reduced reproduction, slower growth and development, and abnormal behavior.
Tens of thousands of chemicals are used in industrial processes and are found in car-maintenance products, household cleaners, toiletries, and many other consumer products.
Our current regimes for controlling whether these chemicals get into the environment are not sufficient for keeping them out of the water, and the potential myriad effects are worrisome.
More generally, the effects of hormone-disrupting chemicals include interrupted sexual development; thyroid system disorders; inability to breed; reduced immune response; and abnormal mating and parenting behavior.
In humans, endocrine disruptors are thought to lead to degraded immune function, mental impairment, decreased fertility, and increases in some types of cancers.
There are a number of negative water-pollution effects from mining operations:
Acid mine drainage: When rain or surface water flows over exposed rock and soil, it can combine naturally causing sulfur to form sulfuric acid.
The acidified rainwater eventually finds its way to streams and groundwater, polluting them and impacting local aquatic life.
Some streams can become so acidic more acidic than car-battery acid the aquatic ecosystem is completely destroyed. The same leaching process that causes acid mine drainage can impart heavy-metal pollutants from the soil and rock as well.
Read Also : The Global Water Pollution Episode
Spills and leaks: Whether it’s a leak in the containment system of a cyanide leach heap or a breach in a coal-slurry impoundment dam, the result is the same—pollution of streams, rivers, and groundwater, killing aquatic life and poisoning drinking water.
Mountain top Removal Mining: In this technique, the tops of coal-rich mountains are removed and the overburden is dumped into nearby valleys, burying stream habitats altogether, with the obvious catastrophic effect on whatever life forms lived in or around the stream.
Marine debris is basically trash in the ocean. Trash fouls inland waterways too, for sure, but trash seems to be a particular problem in our seas.
The Ocean Conservancy calls marine debris one of the world’s most pervasive marine pollution problems.
The debris includes escaped inland trash and garbage thrown overboard by ships and boaters plastic bottles and bags, six-pack rings, cigarette butts, Styrofoam, etc.
Marine animals can swallow the trash items, which often look similar to prey they would normally eat, or the trash item may have barnacles or other delectables attached and is inadvertently ingested with the food.
For instance, sea turtles will eat a plastic bag believing it to be a jellyfish. The bag can cause an intestinal blockage and sometimes death.
A new and potentially devastating effect of marine debris is emerging. After years of degradation at sea, plastic breaks up. The plastic has not biodegraded but rather has disintegrated into very small pieces.
Marine animals near the bottom of the food chain are now ingesting these teeny- tiny little pieces of plastic pollution. How far up the food chain the stuff will go is unknown.
Discarded or lost fishing gear line, rope, nets and certain trash items can get wrapped around marine animals fins or flippers, causing drowning or amputation. Marine debris can also degrade coral reefs, sea grass beds, and other aquatic habitats.
It’s easy enough to see how discharging the heated-up water from a power plant into a river could cause problems for aquatic organisms used to having their water home stay at a fairly specific temperature.
Indeed, industrial thermal pollution is a problem for our waterways fish and other organisms adapted to a particular temperature range can be killed from thermal shock, and the extra heat may disrupt spawning or kill young fish.
Additionally, warmer water temperatures lower the dissolved oxygen content of the water. That’s a double-whammy to aquatic organisms, since the warmer water also causes them to increase their respiration rates and consume oxygen faster. All this increases aquatic organisms’ susceptibility to disease, parasites, and the effects of toxic chemicals.
Global warming is imparting extra heat to our oceans, which have absorbed about 20 times as much heat as the atmosphere over the past half-century.
The ocean is a complex system, and scientists don’t know yet what all of the effects of this type of “water pollution” will be, but here are some likely ones: Sea levels will rise (because of thermal expansion and melting ice), increasing coastal flooding and inundation.
There will be more intense hurricanes as they gather additional strength from warmer surface waters.
Temperature-sensitive species like corals will see tougher times. The Pew Oceans Commission notes that an increase in the mean sea- surface temperature of only 2 degrees F could cause the global destruction of coral reef ecosystems.
In summary, with almost 80 percent of the planet covered by oceans, people have long acted as if those bodies of water could serve as a limitless dumping ground for wastes.
However, raw sewage, garbage, and oil spills have begun to overwhelm the diluting capabilities of the oceans, and most coastal waters are now polluted, threatening marine wildlife. Beaches around the world close regularly, often because the surrounding waters contain high levels of bacteria from sewage disposal.
Pollution may not damage our health immediately but can be harmful after long term exposure. Human infectious diseases are among the most serious effects of water pollution, especially in developing countries, where sanitation may be inadequate or non-existent.
Discharges of nitrogen, phosphorus, and other nutrients come from agriculture, waste disposal, coastal development, and fossil fuel use.
Pesticides are carried in rainwater runoffs from farm fields, suburban lawns, or roadside embankments into the nearest creeks and streams.
When oil pollution gets in water, some of the components are degraded and dispersed by evaporation, photochemical reactions, or bacterial degradation.
Exposure to mercury in the womb can cause neurological problems, including slower reflexes, learning deficits, delayed or incomplete mental development, autism, and brain damage.
Industrial thermal pollution is a problem for our waterways fish and other organisms adapted to a particular temperature range can be killed from thermal shock, and the extra heat may disrupt spawning or kill young fish.
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