In the previous post, we discussed what is water pollution. Let us now investigate some of the different types of water pollution present. The United States Environmental Protection Agency (EPA) has six main categories for water pollution (Environmental Protection Agency, 2016):
1. Plant nutrients
Nitrates/Ammonia and phosphates are used as nutrients by plants. In natural conditions, these nutrients aid in the growth and health of plants. However, when fertilizers, sewage and industrial wastes are washed into a water body, the over addition of nitrates and phosphates is called eutrophication which will lead to an algal bloom. The water will quickly turn green and cloudy, resulting in little light reaching the plants at the bottom of the water body. These water plants will end up dying and decomposing leading to sharp drops in oxygen levels in the water. Compounded with the high oxygen intake from the algal bloom, oxygen will decrease sharply in the water and hence disrupt aquatic life and even cause massive die-offs (Wright, 2003).
2. Sedimentation
Sediments are solid mineral or organic matter from the land that ends up in water bodies. While sedimentation is a natural process, human activities have significantly increased sedimentation due to increased construction and agricultural operations as well as logging and urbanisation (Engler, n.d.). Increasing levels of sedimentation can cause problems like the clogging of waterways, the smothering of aquatic plants as well as causing the water to become murky.
3. Biodegradable wastes
When human and animal wastes enter the water supply, there will be a sharp increase of bacteria that is able to utilize these as an energy source. When a steady supply of sewage is continuously being pumped into rivers and water bodies, such bacteria will reach extremely high populations. These bacteria will decompose the wastes and carbon dioxide is released as a by-product of respiration and oxygen will be rapidly consumed. A drop in oxygen and a spike in carbon dioxide levels will lead to the death of all aquatic life in that water body. This form of pollution is far more common than most other forms of pollutants especially along rivers which supports human communities.
4. Toxic or hazardous wastes
Usually, toxic or hazardous wastes that enters our waters would generally refer to man-made materials or chemicals that were not treated or disposed of properly. Oil spills, industrial discharges and pesticide runoff are examples of chemical wastes while items like nets and plastics are examples of hazardous objects that were not disposed of correctly. Although it may seem that most of the chemical pollution originate from factories and agriculture, did you know that domestic and personal usage of chemicals surprisingly contributes significantly to chemical pollution? Household cleaning products and pesticides are but a few of the chemicals which we use very commonly. These chemicals are toxic and may accumulate when poured down drains.
5. Radioactive wastes
Radioactive pollutants may form occasionally from natural isotopes like radon found in igneous and metamorphic rock, shale, phosphate rock and in rare cases, common rocks like limestone (Godish, 2016). It is important to note that the concentration of radioactive pollutants in water bodies formed due to natural means would be too little, if not negligible to be harmful to us. However, radioactive pollutants in wastewater discharges from factories and uranium mines are in much higher concentrations and are very dangerous to us. These pollutants become very troublesome to deal with as it takes many, many years before it is no longer dangerous.
6. Temperature
Heat is considered to be a source of water pollution. An increase in water temperature leads to a drop in dissolved oxygen levels. External factors like an increase in turbidity can lead to an increase in temperature as murky water absorbs more solar radiation. Factories and power plants, when unregulated, will discharge heated water used for cooling into rivers thereby resulting in thermal pollution. An increase in temperatures and a decrease in dissolved oxygen will negatively affect aquatic organisms.
In my next post, I will discuss about how some of our junk that gets washed out into the sea will affect a specific marine organism.
Reference:
Engler, R., n.d. Sedimentation – Water, Effects, Environmental, Disasters, Types, Soil, Chemicals, Fresh, Human, Sources, Use, Life, Health. [online] Pollutionissues.com. Available at: <http://www.pollutionissues.com/Re-Sy/Sedimentation.html> [Accessed 25 June 2020].
Environmental Protection Agency, 2016. Summaries Of EPA Water Pollution Reporting Categories Used In The ATTAINS Data System. [online] United States. Available at: <https://www.epa.gov/sites/production/files/2016-02/documents/160112parent_plain_english_descriptions_finalattainsnames.pdf> [Accessed 26 June 2020].
Godish, T., 2016. Indoor Environmental Quality. Boca Raton: Chapman and Hall/CRC.
Wright, J., 2003. Environmental Chemistry. London: Routledge.
