WATER POLLUTION: POLLUTANTS, CAUSES, CONSEQUENCES - ENVIRONMENT

The pollution of water or water is any alteration of its physicochemical characteristics or biological harmful to the environment and life. It is also called water pollution, and is determined by the presence of pollutants.

Pollutants can be chemical, physical or biological, of which chemicals are the most common. These reach the water through discharges, spills, wastes and direct or indirect deposits, causing damage to the organisms that inhabit or consume it.

Water pollution with fecal substances in Korogocho River, Nairobi, Kenya Source:

Doreen Mbalo

Water pollutants include detergents, oils, petroleum and its derivatives, fertilizers and pesticides, heavy metals, and plastics. The main sources of pollution are large cities, industries, oil activity, mining, agriculture, and traffic by seas and rivers.

To solve the problem of water pollution, the solution is complex and includes carrying out scientific research and public awareness campaigns. In addition, an adequate treatment of sewage must be done and strict environmental regulations must be established.

Water pollution around the world

In Latin America there are serious water pollution problems, most of which come from untreated urban and industrial effluents and mining.

In Mexico, the north of the country is one of the areas with the highest water pollution due mainly to heavy metals. In this area, the sources of contamination are urban, industrial, mining and agricultural effluents.

In Colombia, water pollution comes basically from urban effluents and agricultural activity. This has resulted in some rivers such as Bogotá and Medellín being considered biologically dead today.

Argentina is another Latin American country highly affected by water pollution from agricultural and urban activity. On the other hand, in some provinces, mining causes serious problems of contamination by heavy metals.

Most of the rivers in Peru show some degree of contamination by heavy metals. Among the main pollutant sources in the country are mining-metallurgical, urban, industrial, agricultural activities and the exploitation of hydrocarbons.

Pollution from fish farming and copper mining waste affects Chile's water bodies. In addition, other sources of contamination of Chilean waters are urban and industrial effluents.

On the European continent, Spain has serious water pollution problems due to agricultural activity and untreated wastewater discharges. For Asturias, pollution from mining activity stands out, and high levels of drugs have been detected in the Ebro river.

Main water pollutants (chemical components)

Agricultural water pollution on a farm in Iowa, USA. Source:

Lynn Betts, photographer

A water pollutant can be both a foreign substance to the ecosystem in question, as well as its own component. For example, phosphorus and nitrogen are very important in nature, but in excess they can cause eutrophication.

In short, a pollutant is any substance that alters the properties or composition of water and affects its usefulness for life.

Detergents

These are the soaps and surfactants that reach water bodies through untreated sewage. Detergents are among the most life-threatening pollutants, breaking the surface tension of cell membranes.

Additionally, detergents contain other water polluting substances such as antiscale, amines, bleaches, antifoams, colorants, perfumes, bactericides and enzymes.

Among the negative effects of detergents are the diffusion of oxygen and the increase in the amount of boron (perborate as bleach) and phosphates in the water.

Oils and fats

Oils and fats have the property of being less dense than water and immiscible with it (they do not dissolve in water). For this reason, once they are discharged into bodies of water, they become serious pollutants.

This occurs because they form a superficial film that prevents the diffusion of oxygen, which results in the death by suffocation of many marine organisms.

Plastics

Many household items are made of plastic, such as containers and bags that become waste. Furthermore, plastic in most of its presentations biodegrades very slowly.

Plastics subjected to conditions of high solar radiation and erosion, produce dioxins and other substances dangerous to life.

Heavy metals

The main human health problems caused by heavy metals are associated with contamination by lead, mercury, cadmium, and arsenic. These and other heavy metals enter the water through untreated urban and industrial wastewater.

Mercury

This heavy metal can be absorbed by drinking contaminated water, accumulates in the body and causes serious health problems. Some mercury damages include intellectual impairment, vision and hearing loss, nervous system disturbances, and kidney damage.

One of the main routes of mercury contamination is the ingestion of contaminated fish.

Arsenic

It is found in water most commonly as arsenate from natural sources or from industrial and urban discharges. The ingestion of this metalloid is associated with various types of cancer, especially skin.

Petroleum and its derivatives

Disaster of the «Prestige» in Galicia (2002)

One of the compounds that causes the most serious damage to the environment as a water pollutant is oil. Spills of crude oil or its derivatives (gasoline, lubricants) in seas and rivers wreak havoc on aquatic life and nullify the potability of the water.

One of the most serious problems of this water pollutant is the high costs and difficulty of remediation of oil spills.

Fertilizers

Fertilizers that are washed away by irrigation water or rain, pollute surface and groundwater bodies. Depending on their formulation, they mainly provide various proportions of nitrogen, phosphorus and potassium.

Likewise, secondary macronutrients such as calcium, magnesium and sulfur (sulfates) can be released from fertilizers. Additionally, micronutrients such as iron, copper, manganese, zinc, boron, molybdenum, and chlorine can be produced.

Although all of these elements are essential for plants, if they are released in large quantities they cause negative effects on aquatic ecosystems. On the other hand, the presence of these elements in aquifers drastically reduces their potability.

In some cases nitrites and phosphates cause eutrophication (increased growth of algae that reduces the amount of dissolved oxygen). By decreasing oxygen levels, the other components of the ecosystem are affected and can die.

Pesticides

There is a great diversity of chemicals used in the control of agricultural pests. These chemicals are frequently carried by irrigation water or rain into bodies of water.

The consequences of pesticide contamination can be serious, as they are highly toxic compounds. Among these we have arsenicals, organochlorines, organophosphates, organometallic and carbamates.

One of the most widely used herbicides worldwide is atrazine, which has been detected in numerous bodies of surface and groundwater.

In countries such as the United States and some countries of the European Community, the use of atrazine has been restricted. However, in others, such as Mexico, it is used without any regulation.

Radioactive waste

Radioactive contamination is caused by the presence of radioactive materials in the water. They can be present in small doses that temporarily stimulate metabolism and large doses that gradually damage the body causing mutations.

The sources of radioactivity can be radioactive sediments and waters used in nuclear atomic plants. They can also originate from the exploitation of radioactive minerals and the use of radioisotopes for medical and research purposes.

Emerging pollutants

Emerging pollutants are called a series of chemical compounds of different origin whose effects as environmental pollutants are not sufficiently known.

These new water pollutants have been detected thanks to the development of better and more sensitive analysis methods.

Some of these are brominated flame retardants, chloroalkanes, polar, perfluorinated pesticides and drugs (antibiotics among others).

Causes of water pollution

Sewage and industrial waters in the New River, the United States and Mexico. Source:

CNRC

Water has different uses, and in each of the processes that involve it, it is susceptible to being contaminated.

The sources of contamination are specific when the source and route of contamination can be clearly identified. In the case of non-point sources of pollution, it is impossible to specify the exact point of discharge of the pollutant.

There are some natural polluting sources, such as heavy metals coming from the erosion of some geomorphological formations. However, the most important and serious sources of pollution come from human activity.

Urban activity

In the home, various substances are used that, as they are not disposed of properly, end up in the drain and pass into the bodies of water.

Some solid wastes as a consequence of domestic activities can pass to aquifers if they are not managed properly.

The waste of electronic devices, batteries and other components, contribute heavy metals such as mercury, lead and cadmium. These wastes can directly or indirectly reach surface or underground water bodies.

Industrial activity

The chemical substances that are produced in the industrial area are very varied, being able to find heavy metals, petroleum derivatives, oxides of nitrogen and sulfur, fats, oils and detergents.

For example, the electronics industry uses arsenicals in the manufacture of transistors, lasers, and semiconductors. These compounds are also used in the glass, textile, paper, and mining industries, among others.

When industrial wastewater is not treated, arsenicals can reach water bodies. Later, they can affect human health by consuming contaminated water or seafood.

The industry also generates gas emissions, which cause acid rain and carry nitrogen and sulfur compounds to the water. Likewise, acidification of soils occurs that indirectly leads aluminum to the water by runoff.

Oil activity

The extraction, storage and transport of oil and its derivatives is one of the most dangerous sources of water pollution.

Oil spills in seas and rivers generate extensive layers that prevent the diffusion of oxygen, causing the death of aquatic animals. In the particular case of waterfowl, they are very affected when their feathers are impregnated with oil.

On the other hand, the remediation work is expensive and difficult and its polluting effects last for long periods of time.

Mining

Open pit mining, especially for gold extraction, is one of the most polluting activities in rivers and lakes.

For the separation of gold from the rocky substrate, mercury, cyanide and arsenic are applied, which are then washed and end up in the water courses.

Other elements that end up contaminating the waters associated with mining activity are selenium, zinc, cadmium and copper.

Additionally, in these mines the chemical and physical weathering of the rock and soil is carried out to extract the minerals. This activity releases heavy metals that end up contaminating both groundwater and surface water courses (rivers and lakes).

Agricultural activity

Intensive agriculture uses a large amount of chemical inputs, such as herbicides, insecticides, fungicides and fertilizers. In some areas such as cotton, the number of pesticide applications throughout the growing cycle is enormous.

Much of these products or their secondary metabolites end up being washed into bodies of water.

In the livestock area, pig farming is one of the most polluting activities. Pig farms produce a large amount of organic waste that is constantly washed from the pig pens.

When proper treatment techniques are not applied, these wastes end up contaminating surface and groundwater.

Marine transport

Maritime traffic is one of the most important sources of waste that pollutes the world's oceans. Solid and liquid waste is dumped into the sea from large cargo ships, ocean liners and fishing fleets.

In the oceans there are true islands of garbage concentrated by ocean currents. These islands are formed by solid waste from maritime traffic, together with contributions from coastal cities.

On the other hand, ships dump various substances into the sea, especially fuels, lubricants and paint residues.

Atmospheric emissions

The atmosphere is another way by which pollutants reach the oceans. The lighter fractions of dust and debris will be absorbed by the wind and blown into the ocean. A large number of dust particles will carry metallic traces, which are distributed in this way.

A second type of air pollution that affects the marine environment is greenhouse gases, which by heating the earth also raise temperatures in the oceans.

It seems that a secondary consequence is that the increase in the concentration of CO ₂ in the atmosphere contributes to the acidification of the oceans. Third, combustion processes (like car engines) produce a significant amount of SO ₂ and NO _{2 as} well. This will increase the occurrence of acid rain.

Runoff and land spills

Unprotected farm fields yield topsoil as well as farm fertilizers and other potential pollutants when heavy rains occur.

Waters from agricultural and industrial processes contain high levels of nitrogen and phosphorus. According to the United States Environmental Protection Agency (EPA), more than 40% of the watersheds in the western United States have been contaminated with metals that end up in the ocean.

Consequences on the environment

Garbage in Lake Maracaibo, Venezuela

Source: The Photographer

Public health

One of the main environmental impacts of water pollution is the effect on public health. The loss of water quality restricts its consumption both for humans and for domestic and industrial activities.

One of the biggest problems is heavy metals, since they are not biodegradable. Therefore, they accumulate in the body causing damage to the nervous, endocrine, and kidney systems, among others.

Contamination with fecal matter results in the possible presence of pathogens that cause different diseases.

Diseases

Uncontrolled rivers, lakes and waters can put the health of swimmers and bathers with gastrointestinal diseases at risk.

Gastrointestinal diseases are caused by Escherichia Coli in fresh water and by Enterococci faecals in fresh and marine water. The range of values to measure water quality oscillates between 30 indicators per 100 ml.

Impact on tourist and recreational activities

Solid and liquid waste discharged into bodies of water negatively affect its use for recreational purposes.

Aquatic recreational activities are restricted, since in polluted waters it is a serious risk to health. Also, bad smells and deterioration of the landscape caused by pollutants restrict the tourist value.

Limitations for industrial and agricultural use

Water pollution limits its use for irrigation and in some industrial activities. Water sources contaminated with heavy metals or biocides cannot be used in agriculture or the food industry.

Flora and fauna

Flora

Eutrophication

Although eutrophication causes the growth of certain algae, its net effect is very serious on the balance of the aquatic ecosystem. By saturating the body with water, they prevent submerged aquatic plants from using oxygen and sunlight.

Mangroves

These ecosystems are very susceptible to water pollution, particularly from oil spills. The oil covers the pneumatophores (aeration roots of mangroves), so the plants die of anoxia (lack of oxygen).

Aromatic compounds also damage cell membranes, causing cells to stop working.

Acid waters

The acidification of the water due to contamination decreases the populations of decomposing organisms (bacteria and fungi). Therefore, the availability of nutrients is affected causing the death of many aquatic plants.

Phosphate excess

Detergents and other pollutants increase the level of phosphates in the water. Phosphate compounds penetrate the roots and affect plant growth.

Fauna

Many of the pollutants in water directly kill wildlife. Others cause endocrine disruptions that lead to reproductive, growth, and behavioral problems.

Bioaccumulation of chlorinated paraffin-type contaminants has been detected in Arctic fish, as well as in birds and marine mammals. This indicates the mobilization capacity of this type of pollutant in the water.

Oil spills, detergents, oils and greases affect dissolved oxygen in water. Additionally, direct damage can occur when oil adheres to the gills of fish or feathers of seabirds, causing death.

Water pollution in Mexico, Colombia, Argentina, Peru, Chile and Spain.

Rio Deba, Basque Country (Spain). Source:

No machine-readable author provided. Txo assumed (based on copyright claims).

Mexico

In Mexico, like other developing countries, there is a deficient water treatment system. One of the most affected areas is the north of the country, where there are serious problems of contamination by heavy metals.

Among other cases, mention can be made of the Abelardo L. Rodríguez water dam, located in Hermosillo (Sonora). The waters of the Sonora river basin reach this dam, which brings a large amount of pollutants from mining, industrial and agricultural activities.

On the other hand, a study carried out in 29 cities in northern Mexico found that 20 of them had worrying levels of some heavy metal. The metals detected were lead, copper, mercury, arsenic and cadmium.

Likewise, the water quality in Mexico City and part of the metropolitan area is low and in few cases treatments are applied to mitigate the problem.

Colombia

The Medellín and Bogotá rivers, close to these two large Colombian cities, are considered to be biologically dead. This situation is a consequence of the high levels of contamination by untreated effluents.

In the coffee growing regions of Quindío, Antioquia, Tolima and Risaralda, and the rice fields of Meta, pesticides have contaminated large areas.

The waters of the Sogamosa Valley and the Magdalena, Dagua and Nechi rivers are polluted by industry and mining.

The rivers that drain through the Colombian Caribbean basin receive large amounts of pollutants such as phosphorus, nitrates, potassium, pesticides (DDT, DDE) and organic waste.

Argentina

In the coastal zone of the province of Buenos Aires, the main sources of contamination come from urbanization and tourist activity. Another important problem in this country is the contamination of water from agricultural activity.

In the northwest of Argentina (provinces of Entre Ríos and Corrientes) there are old swampy areas (natural wetlands) that were transformed into rice fields. In this area, the indiscriminate use of pesticides and fertilizers has generated heavy water pollution.

For Jujuy, Tucumán, Catamarca and other regions, contamination of aquifers with copper and sulphates discharged by effluents from copper and gold mines has been detected.

Peru

According to the National Report on Water Management in Peru, many of the waterways are contaminated by untreated discharges.

Among the main sources of contamination are mining-metallurgical, urban, industrial, agricultural, and hydrocarbon exploitation.

For example, the water in 22 of Peru's rivers exceeds the permitted levels of cadmium and in 35 there is a high content of copper.

On the Pacific slope, the Moche or Cañete rivers present levels above what is allowed in all the heavy metals analyzed. In addition, the rivers of the Titicaca basin have impermissible levels of copper and zinc.

Chile

According to the Chile 2016 environmental performance evaluation, the main sources of contamination of the aquifers are urban and industrial wastewater.

Similarly, fish farming and fish processing, agriculture and the food industry are sources of pollutants.

In the center of the country, there are eutrophication problems as a consequence of runoff from agricultural land. This has generated fertilizer contamination of coastal lagoons, estuaries and wetlands.

In the southern region there is antibiotic contamination in the fjords, as well as eutrophication. This situation is caused by wastes from salmon farming and other branches of aquaculture.

The Maipo River is the main source of drinking and irrigation water in the metropolitan region of Santiago and Valparaíso. However, it currently has significant levels of copper contamination as a result of mining activity.

Spain

According to a report by the Spanish subsidiary of Greenpeace, most of Spain's river basins are affected by chemical contamination of water.

The investigation indicates that 70 Spanish cities fail to comply with the European standard for wastewater treatment. In addition, he points out that among the most polluted rivers are the Jarama, the Llobregat and the Segura.

Ebro river

The Ebro is the main river in Spain and in its basin there is intense agricultural and livestock activity, urban development and some industrial activity.

In a study carried out within the framework of the European project AQUATERRA, the most relevant pollutants were determined. The research found that the most abundant are drugs, as well as pesticides from agricultural activity.

Among the pesticides, the most frequent are atrazine and simazine, used in corn and grapes. These pesticides contribute to the river an annual load of 800 Kg. And 500 Kg. Respectively.

Among the most common drugs in the Ebro waters are acetaminophen (paracetamol), atenolol (beta-blocker), carbamazepine (antiepileptic) and ibuprofen (anti-inflammatory).

In total, about 30 drugs have been monitored, representing 3 tons of annual discharges.

Deba River

In the Deba river (Basque Country) the presence of highly toxic compounds has been detected in the sediments, due to industrial discharges. These include DDT, PAH (polycyclic aromatic hydrocarbons), AOX (absorbable organic halides), ethylbenzene, and toluene.

Osona River

In the Osona river basin in Catalonia there is a high concentration of cattle farms. Discharges and runoff waters contribute large amounts of nitrates, so that the waters of torrents and rivers are not suitable for consumption.

Solutions

Improve knowledge and raise awareness

The starting point of the solution to a problem as complex as water pollution is knowledge.

That is why scientific research is essential to understand all the variables involved. From these studies, information can be generated for citizen awareness programs and the generation of suitable technological alternatives.

Sewage treatment

One of the most effective measures is the treatment of sewage or wastewater. Therefore, it is essential to install treatment plants that purify the water before returning it to the natural environment.

The most advanced treatment plants include a combination of physical, chemical and biological processes. These processes allow the extraction of most contaminants from contaminated water.

For this, coagulating agents such as aluminum sulfate are used, subjecting the water to coagulation-flocculation, sedimentation, filtration and finally chlorination.

Regulation of industrial emissions and discharges

In most developing countries there is no adequate legislation to regulate emissions and discharges from industry or it is not enforced. This situation aggravates the problem of water pollution in these countries.

Therefore, it is necessary to generate legislation that can strictly control industries and oblige them to reduce their environmental impact.

Restrictions on the use of pesticides and fertilizers in agriculture

The rational use of fertilizers and pesticides is very important to avoid water pollution. The implementation of good agricultural practices with an ecological sense, contributes to diminish the dependency of chemical products for the production.

Restrictions and controls in mining activity

Mining, especially in the open pit, has a high impact on water quality. It is essential to restrict this activity in the areas near the aquifers and to prohibit the most aggressive technological practices with the environment.

Controls in the extraction, storage and transport of hydrocarbons

One of the most polluting industries is that of oil and its derivatives (petrochemicals, plastics and others). In the extraction phase, spills and accumulation of sludge rich in heavy metals pollute surface and groundwater.

Then, in transport, minor spills and even major accidents are also frequent. Therefore, a stricter control of oil activity is necessary in terms of its potential environmental impact.

Priority lists and maximum levels allowed

It is of great importance to continue generating the lists that contain chemicals considered dangerous to human health. In these, the maximum levels allowed in water for human consumption are defined.

References

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Greenpeace Spain (2005). Water. The quality of the waters in Spain. A study by basins. 136 p. This report is available in electronic version on our website: www.greenpeace.es
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WATER POLLUTION: POLLUTANTS, CAUSES, CONSEQUENCES - ENVIRONMENT - 2025