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Have you ever been to the Lake District? It's the biggest National Park in England, and also home to a single lake, one of the biggest in the UK, and the deepest in England. Recent water Pollution, however, is resulting in the breakdown of aquatic ecosystems in Lake Windemere. Private septic tanks and inappropriate waste disposal from plants are causing an influx of dangerous chemicals and nutrients. This poses a risk to both aquatic life and humans.
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Jetzt kostenlos anmeldenHave you ever been to the Lake District? It's the biggest National Park in England, and also home to a single lake, one of the biggest in the UK, and the deepest in England. Recent water Pollution, however, is resulting in the breakdown of aquatic ecosystems in Lake Windemere. Private septic tanks and inappropriate waste disposal from plants are causing an influx of dangerous chemicals and nutrients. This poses a risk to both aquatic life and humans.
There are lakes, rivers, and oceans all over the world that are being threatened by water Pollution. Today we are going to be looking at some examples of water pollution, how water pollution is caused, and the effect polluted water has on human populations and ecosystems.
Fig. 1. The Lake District at sunset. Source: Unsplash.
Water pollution is the alteration of the natural composition of a body of water. This can be by the addition of chemicals, metal particulates, radioactivity, or even heat. Some natural causes can result in water pollution however human activity is the major driver behind the contamination of global waters.
There are two types of pollution: point-source pollution and non-point source pollution:
Point source pollution is contamination that can be attributed to a certain area or exact point. Sewage pipes and industrial discharge channels are examples of pollution which can be pinpointed.
Non-point source pollution is contamination that stems from a general area and can be difficult to quantify. Examples of non-point source pollution are runoff from agricultural areas and acid rain.
Governments will find non-point source pollution difficult to attribute and control directly, so strict laws and legislations must be put into place to reduce the general release of pollutants.
For example, the Clean Water Act (CWA) in the US1, passed in 1972, regulates the emission of water pollutants, including non-point pollution. One of the most affected landscapes by unregulated water pollution in the US was wetlands. The regulation of water pollution through the CWA helped protect not only drinking water but also the wetlands.
Fig. 2. Wetlands. Source: Unsplash.
Let's have a look at some examples of water pollution:
In theory, you can consider the introduction of non-native species to an aquatic environment as water pollution. This can occur by humans physically carrying alternative species into the habitat, or climate change forcing species to migrate to more suitable habitats. These species will take up space, compete for resources, and potentially become novel predators, which can seriously disrupt an ecosystem's balance.
Eutrophication is a process we cover a lot, but it is one of the worst consequences of polluted water. An influx of nutrients from agricultural runoff, industrial runoff, or sewage will cause algal populations to increase at a rapid rate. This will Lead to a phenomenon called an algal bloom, which covers the surface of the water. These algal blooms will block the penetration of sunlight into the ecosystem and when they are broken down by aerobic decomposers, the available oxygen will be sucked up. This severely disrupts the ecosystem of the river or lake affected by an algal bloom.
Fig. 3. Algal blooms prevent the sunlight from reaching deeper parts of the water, causing plants below the surface to receive less light. Increased oxygen consumption will reduce the chances of other species to respire in the water. Competition for resources will be harsher and the environment will suffer from a lack of nutrients. Source: Unsplash.
So now we know the different types of water pollution; what causes the addition of these substances to the water? There are six main causes for water pollution:
We'll have a look at each of these causes in more detail in the sections below.
In highly populated areas, massive amounts of human and animal sewage are treated daily. This sewage will contain animal faeces and detritus, so will contain lots of organic nutrients and lots of bacteria. The disease-carrying pathogens will pose a threat to human health, while the decomposing bacteria will suffocate the waters of their oxygen and release lots of nutrients. Sewage treatment facilities are often focused on eliminating some of the dangerous chemicals that can be released into the water like oils, metals, acids and alkalis, rather than the seemingly less dangerous bacteria and organic nutrients. However, the combination of decomposing bacteria and nutrients is harmful to entire ecosystems and the quality of drinking water.
Detritus is waste of any kind, and often refers to animal excrement or dead organic matter.
Farmers need to produce enough food to feed the population and earn money to make a living, so the environmental implications of their methods are not always considered. The overuse of artificial fertilisers and pesticides is endangering nearby aquatic ecosystems. Agricultural fertilisers contain nitrogen and phosphorus for plant growth, so you can imagine how much is needed for a field of crops (then think about entire agricultural regions!). After rainfall, the water (containing nitrogen and phosphorus ions not taken up by plants) will run off into nearby aquatic waters, which can cause oxygen depletion. Pesticides will also be present in the runoff and will contain poisonous chemicals as their purpose is to kill and deter species.
Fig. 4. Can you imagine the amount of artificial fertilisers and pesticides that is needed to optimise the production of this field? And this is only one farmland! Source: Unsplash.
Regenerative agriculture practices sustainable methods which aim to maintain and improve soil quality. Healthy soils will produce greater yields and larger crops. Regenerative practices include limiting physical disturbance of soils (such as tillage), covering soils with temporary crops, and leaving perennial wild crops. Healthy soils will require fewer fertilisers and pesticides, so reduce water pollution in the area too.
Industrial processes involve the use of chemicals and particulates which are poisonous, radioactive, or carcinogenic in water. Runoff from industrial areas and poorly treated industrial waste will contain large amounts of dangerous metal compounds (mercury, aluminium, chromium), radioactive chemicals (uranium, plutonium), and acidic compounds. The discharge of cooling water from power plants can cause heat pollution as well. Despite being called 'cooling water', it is much warmer than the water in lakes, rivers, and oceans, and can cause drastic changes in temperature which can have a knock-on effect on ecosystems.
Oil spills are the most catastrophic example of industrial discharge. They can completely change the composition of water: shifting pH levels, releasing poisonous chemicals, and causing hypothermia.
The combination of agricultural, industrial, and runoff can form dangerous sedimentation that piles into coastal ecosystems. Sediment influx can introduce massive amounts of nutrients and smother benthic organisms (organisms that live at the bottom of the body of water), killing many species and providing the conditions for the rise of producers which lack the provisioning value to form stable foundations of aquatic ecosystems.
In densely populated urban areas, dumped litter and waste can make their way into nearby waters. Improperly disposed waste from cities and general public litter in the form of plastics, food, metals, and electronics can contain all sorts of toxic and radioactive chemicals (metal compounds, hydrocarbons, solvents). The degradation of waste only releases more of these chemicals.
Underdeveloped countries with smaller populations still produce massive amounts of waste because of their limited laws and companies involved in removing waste.
Acid rain is rain that has turned so acidic that it causes harm to the environment.
Nitrous oxides and sulphur dioxide emissions from power plants can cause acid rain. These gaseous particles will react with water vapour molecules in clouds to form nitric acid and sulfuric acid and then fall as acidic precipitation (pH < 5.2). Acid rain can pour directly into waters and increase pH or runoff from soils and carry harmful chemicals with them.
An increase in pH increases the likelihood of poisonous aluminium ions being isolated from aluminium hydroxide in soils. Aluminium ions stunt root growth in plants so can affect producer populations when they run into water.
Evaporating polluted waters (containing nitrate ions) can cause acid rain too.
Anthropogenic global warming is causing heat pollution of waters. Many marine species become stressed in warmer environments and require more oxygen to match their increasing metabolic rates. Carbon dioxide (CO2) emissions are causing ocean acidification as well, which reduces carbonate availability. Organisms with calcareous shells and exoskeletons require carbonates to survive.
Fig. 6. Crabs are one of the species that have an exoskeleton and can be affected by a reduction in carbonate availability. Molluscs and other bivalves also suffer from a lack of carbonate.
Carbon dioxide dissociates to form carbonic acids, which then react with carbonates to form bicarbonates, which are not very useful!
As you can imagine, with water being such a crucial part of human and wildlife life, polluted water causes severe problems for the ecosystems and for the human species. Check out our Impacts of Polluted Water article for more detail, but here are some of the consequences of polluted water:
There are many solutions to prevent water pollution, this can be by introducing widespread regulations or by stopping a point of serious pollution. Here are some examples:
Remember the difference between point source pollution and non-point source pollution. The strategies to combat each type of pollution will depend on the source and how easy it is to pinpoint the source.
Hopefully, you now know more about water pollution. Remember that water pollution is the alteration of the natural composition of a body of water and can be caused by humans but also by natural causes.
Water pollution is the addition of contaminants to a water source.
The causes of water pollution are:
Yes, nuclear power plants can pollute water. Pollution of water by nuclear plants happens because nuclear waste is released as discharge, sulphur dioxide and nitrous oxide emissions cause acid rain, and the release of 'cooling water' warms waterways.
Urbanisation causes water pollution because it produces lots of waste which can pollute waters when improperly disposed of.
To reduce water pollution from factories, used water must be treated before being released into water sources.
Flashcards in Polluted Water29
Start learningWhat is water pollution?
The addition of contaminating agents to a water body?
What are examples of pollutants?
Fertilisers, pesticides, metal compounds, acids, alkalis, pathogens, heats.
What elements are found in fertilisers?
Nitrogen, phosphorus, and potassium.
Why may invasive species be considered polluting?
Because they change the composition of the ecosystem and impact the wildlife.
How does improper wastewater treatment pollute waters?
Sewage often contains huge amounts of bacteria and nutrients that will harm waters.
What is detritus?
Detritus will often refer to animal waste, including faecal and dead, organic matter.
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