Sorry for the late post as I was busy preparing for an interview. But let’s get diving again, into today’s topic on eutrophication!

Nutrients are essential for living things to survive and carry out day-to-day activities. However, too much nutrients can lead to disastrous consequences, especially for living things, such as fishes, in freshwater bodies. This process, known as eutrophication, occurs when too much nutrients end up in a water body. “Harmful algal blooms, dead zones and dead fishes” are all negative impacts caused by eutrophication (NOAA, n.d.).

To understand more about eutrophication and its causes, you may want to watch the video that I embedded in this blog post (see Video 1). It all begins when chemicals, such as nitrates and phosphates, are discharged from land into water. In some cases, these chemical runoffs comes from fertilisers used in agriculture, or even detergents. Once these chemicals, or “nutrients”, reach the water body, it causes algae to reproduce and grow in numbers quickly. This is the beginning of a vicious cycle…

Once there is an algal bloom, the algae blocks out the sunlight and prevents freshwater plants from photosynthesising. This causes a decrease in oxygen levels and also the death of these plants. Once the algae dies too, its organic matter sinks to the bottom of the freshwater body, a lake, for example. It then accumulates with the decaying matter of the aquatic plants. Bacteria and other decomposers then break down these organic matter, with an excessive consumption of oxygen, depleting oxygen levels. More nutrients are then returned back into the water body, causing further algal growth. Concurrently, toxic substances such as hydrogen sulphide and ammonia are produced. Finally, when the rate of consumption of oxygen by the bacteria (to decompose the organic matter) is higher than the rate of oxygen replenishment, an anoxic (absence of oxygen) environment is produced in the lake, killing the other living things.

Video 1: What is eutrophication? (Source: FuseSchool – Global Education, on YouTube)

Indeed, eutrophication is disastrous and we should learn how to discharge our (chemical) wastes correctly. This is to reduce the negative implications caused by eutrophication and its harm to the environment.

References:

NOAA. (n.d.). What is eutrophication? National Oceanic and Atmospheric Administration. https://oceanservice.noaa.gov/facts/eutrophication.html

You probably have heard about oil spills being a prominent disaster. Indeed, oil spills are major catastrophic events that threaten marine environments. They are a major form of marine pollution, and sometimes, occur even in freshwater.

Quoting the National Oceanic and Atmospheric Administration (NOAA) (n.d.), oil spills are most often “caused by accidents involving tankers, barges, pipelines, refineries, drilling rigs and storage facilities”. Most of the spilt oil spreads out rapidly to form a thin layer of oil slick (NOAA, n.d.). However, in rare cases, oil that has heavier components may sink (NOAA, n.d.).

Oil spills have a huge, negative implication on the environment. In and on the ocean, and even on beaches and shorelines, oil spills “can be very harmful to marine birds, sea turtles and mammals, and also can harm fish and shellfish” (NOAA, n.d.). In the case of mammals, oil destroys the insulating abilities of their fur (NOAA, n.d.). Oil can also damage the water-repelling abilities of a bird’s feather (NOAA, n.d.). Many animals also swallow oil accidentally when cleaning themselves or eating prey that is coated with oil (NOAA, n.d.). Fish and shellfish can also ingest oil, which changes reproduction rate and growth rate, and may even cause death (NOAA, n.d.). In turn, this leads to a decline in sources of (sea)food for humans.

As can be seen from Figures 1 and 2, oil spills, such as these caused by the explosion of an oil rig (the Deepwater Horizon in this case), can lead to detrimental effects on the marine environment. Figure 1 shows brown pelicans that were captured to be cleaned. The oil spill caused by the explosion of the Deepwater Horizon had coated the birds’ feathers with oil. Figure 2 shows a photograph of the oil rig’s explosion. Figure 3 shows the extent and widespread impact of the spill on the Gulf of Mexico.

Figure 1: Brown pelicans coated with oil from the Deepwater Horizon oil spill (Source: https://www.britannica.com/science/oil-spill)

Figure 2: Explosion of the Deepwater Horizon (Source: https://www.britannica.com/event/Deepwater-Horizon-oil-spill)

Figure 3: Areal extent of the Deepwater Horizon oil spill (Source: https://www.britannica.com/event/Deepwater-Horizon-oil-spill)

To conclude, this week’s blog post has done a quick summary of oil spills. I focused on the environmental and ecological impact of oil spills and also its causes. Next week, I will move on and explore freshwater pollution, especially those caused by chemical runoffs into rivers. The blog post will also cover eutrophication and bioaccumulation (and biomagnification). Dive in!

References:

Britannica. (n.d.). Deepwater Horizon oil spill. Britannica. https://www.britannica.com/event/Deepwater-Horizon-oil-spill

Britannica. (n.d.). Oil spill. Britannica. https://www.britannica.com/science/oil-spill

NOAA. (n.d.). Oil spills: A major marine ecosystem threat. National Oceanic and Atmospheric Administration. https://www.noaa.gov/explainers/oil-spills-major-marine-ecosystem-threat

“Safe and readily available water is important for public health, whether it is used for drinking, domestic use, food production or recreational purposes. Improved water supply and sanitation, and better management of water resources, can boost countries’ economic growth and can contribute greatly to poverty reduction” (World Health Organization, 2019).

The importance of safe drinking water is irrefutable. In 2010, the UN General Assembly explicitly acknowledged and recognised that everyone should have the right to safe drinking water and also clean water for sanitation and other uses (World Health Organization, 2019). However, despite its importance and significant role in our daily lives, our drinking water is still heavily polluted.

The most common implication of unsafe drinking water is waterborne diseases. “Waterborne diseases are usually caused when a person drinks, bathes in, washes with or prepares food with water that has been contaminated by bacteria, viruses or parasites, usually from human or animal waste” (World Vision, 2021). According to the United Nations Department of Economic and Social Affairs (UNDESA) (2014), every day, 2 million tons of sewage, effluents and wastes are discharged into the world’s waters. Even more shockingly, annually, more people die from unsafe water than from violent events such as wars (UNDESA, 2014). Linking back to human health, contaminated, polluted water, coupled with poor sanitation, are linked to transmission of diseases such as cholera, diarrhoea, hepatitis A, and typhoid, among many other diseases (World Health Organization, 2019). Each year, unsafe water causes about 1 billion people to become ill (NRDC, 2018).

Waterborne diseases are usually caused by pathogens such as bacteria and viruses (NRDC, 2018). Diarrhoea is an example of such an illness. Although easy to deal with in clean, sanitary conditions, it should be understood that many developing regions in the world still has no access to clean water, thus making diarrhoea hard to deal with.

Waterborne diseases are also increasingly transboundary and political. An interesting case study that I would like to point out in this blog post is that of the 2010 Haiti cholera outbreak. In 2010, nine months after a deadly earthquake struck Haiti, a cholera outbreak occurred. The media portrayed the epidemic as caused by the earthquake (Piarroux, 2011). However, this was not true as it was admitted by the UN years later that the outbreak could have been caused by Nepalese troops who were in Haiti for peacekeeping (Sidder, 2016). Surprisingly, it was already suspected in Piarroux (2011) that “a rumor held recently incoming Nepalese soldiers responsible for importing cholera”. Before I move on, it should be recognised that cholera has not occurred in Haiti for more than a century (Piarroux, 2011).

What happened in reality is shocking and political. In fact, the United Nations (UN) camp which hosted these Nepalese troops was discovered to have discharged wastes into the nearby Meille River (Sidder, 2016). Just not long before the troops arrived at Haiti, Nepal was experiencing a cholera outbreak too (Piarroux, 2011). After arriving in Haiti, the virus ended up in the river because the wastewater was untreated. Subsequently, as this river is the primary source of water for the people of Haiti and also because they have no treatment options for the water, the virus ended up causing a massive (and messy) outbreak. The UN, a supranational organization, to maintain its credibility and reliability, probably did not want to admit to being the cause of the epidemic initially. Overall, this case study has shown us how waterborne diseases can be transboundary (happening across two or more nations) and also political (who controls the knowledge and media) at the same time.

References:

Denchak, M. (2018, May 14). Water Pollution: Everything You Need to Know. NRDC. https://www.nrdc.org/stories/water-pollution-everything-you-need-know

Piarroux, R. (2011). Understanding the cholera epidemic, Haiti. Emerging Infectious Diseases, 17(7), 1161–1168. https://doi.org/10.3201/eid1707.110059

Sidder, A. (2016, August 19). How Cholera Spread So Quickly Through Haiti. National Geographic. https://www.nationalgeographic.com/science/article/haiti-cholera-crisis-united-nations-admission.

United Nations Department of Economic and Social Affairs. (2014, October 23). Water Quality. International Decade for Action ‘WATER FOR LIFE’ 2005-2015. https://www.un.org/waterforlifedecade/quality.shtml

World Health Organization. (2019, June 14). Drinking-water. World Health Organization. https://www.who.int/news-room/fact-sheets/detail/drinking-water

World Vision. (2021, July 6). Waterborne disease facts and how to help. World Vision. https://www.worldvision.ca/stories/clean-water/cholera-waterborne-disease-facts