Activity 3. Surface water pollution and implications for the oceans
Surface water – rivers, lakes, streams – flows into the seas and oceans. Their pollution therefore directly affects and influences the water quality of the world’s oceans.
А. Read the following informative text:
Water pollution from sewage
Sewage is a point source pollutant – it is wastewater from residential, commercial and industrial buildings. Sewage pollution is usually the residual or excess water that is left after domestic and industrial activities such as washing clothes, washing dishes, bathing, etc., and this water usually contains many chemicals. Careless disposal of wastewater – domestic, industrial and agricultural – creates a chain of problems such as the spread of disease, disruption of ecosystems, economic losses.
Effective wastewater treatment systems are built and maintained in many developed countries. This is done by discharging it either to on-site septic systems or to centralised treatment plants. In both methods, the wastewater is treated before being discharged into a stream, river or coastal outfall. This takes place either underground (in the case of septic tanks) or in receiving surface water bodies (in the case of sewage treatment plants).
What is the impact on human health and the environment?
Every year, hundreds of billions of gallons of untreated sewage flow into our rivers, lakes and coastal waters. Unknowingly, many people and their loved ones risk becoming seriously ill when untreated sewage gets into the water they use for recreation or drinking. The Environmental Protection Agency estimates that up to 3.5 million people get sick from swimming in waters polluted by sewage overflows alone. However, the number of illnesses caused by untreated sewage may be much higher than we think. A large number of people who get sick for this reason do not report it to their doctors. Most illnesses that occur from contact with sewage are caused by pathogens, which are biological agents that cause disease or illness in the host. The most common illnesses that people experience are food poisoning, diarrhea, vomiting, fever, and skin irritation.
In addition to pathogens, high levels of nutrients in untreated wastewater can lead to excessive algal blooms and thus impede photosynthesis of aquatic plants. Polluted water leads to a reduction in the amount of oxygen and a build-up of toxic substances in the water, and this is the cause of death for many aquatic organisms.
Some pollutants seep into the soil and end up in groundwater, which is a major source of drinking water.
B. Examine the diagrams. Solve the tasks.
Source: https://sewageoceanpollution.weebly.com/uploads/2/5/4/2/25420761/1377160.jpg
- How much of ocean pollution comes from surface water?
- Rank the sources of ocean pollution, starting with the most significant.
Source: https://sewageoceanpollution.weebly.com/uploads/2/5/4/2/25420761/2001888.jpg
- Is industry or agricultural activity a more dangerous source of pollution?
Source: https://sewageoceanpollution.weebly.com/uploads/2/5/4/2/25420761/342294_orig.jpg
- Name the two countries that pollute the most the surface waters flowing into the ocean.
- How much polluted surface water is India dumping into the ocean?
- Is Japan or South Korea a bigger polluter?
- List the most important impacts of surface water pollution on the oceans.
