Question

1. Eutrophication is an example of a positive feedback loop, where change in the system promotes further change in the same direction. Describe another environmental issue that has synergistic effects with cultural eutrophication and how it exacerbates the problem.

1. How can we limit cultural eutrophication? Discuss two methods and their potential impacts.
2. What is stormwater runoff and why is it primarily a concern in urbanized areas?
3. What are three types of pollutants that could be carried in stormwater runoff? Discuss their sources and potential environmental impacts.
4. Describe two other potential sources of water pollution that contribute to the recommendation not to swim after a heavy rain.

Answer 1

Eutrophication is a natural process of enrichment of nutrients mainly nitrogen and phosphorus in a water body which leads to depleted level of oxygen.

Cultural eutrophication is anthropogenic which speeds up the natural eutrophication. It is the the change in nutrients input due to human activities like dumping of fertiliser and sewage waste in water bodies.
The most striking effect of cultural eutrophication is the Algal bloom. It is the excessive growth of microscopic algae commonly Cyanobacteria. Excessive algae uses all the oxygen in the water which reduces the availability of dissolved oxygen for other organisms like fish etc. This leads to the death of organisms. Algal growth also leads to limited penetration  of sunlight inhibiting growth of aquatic plants.

Cultural eutrophication can be limited by following ways.

1 ) Waste water  should be properly treated before it is discharged into the water body.

2 ) Instead of using fertiliser which contain high amounts of nitrogen and phosphorus, manures should be used in agricultural practices.

Stormwater runoff is the result of precipitation on land which mixes with the harmful pollutants and drain them along in rivers, streams and other water bodies or infiltrate into the soil thus polluting it.
In urbanised areas there is a lot of impervious space, excessive use of fertiliser, wastes from recreational uses etc which result a lot of pollutants. When precipitation falls on this area it carries pollutants along with it and pollutes soil and water bodies.

Stormwater runoff carries pollutants like grease, oil, heavy metals from cars, fertiliser etc. Sources of stormwater runoff are many like lawn fertiliser, pet waste, materials from construction sites etc.

Among the harmful effects of stormwater runoff are -

1) watershed contamination which leads to degraded quality of drinking water supply.
2)It May also degrade the quality of water for commercial and recreational purposes.