Question

A lake has begun to degrade due to an increase in human activity and urbanization. The main cause of this degradation is that the oxygen carrying capacity of the water has decreased due to an increase in the discharge of organic substances (especially phosphates) in the lake due to fertilizer runoff from local farms. This increase in organic substances has allowed aquatic plants, including algae, in the lake to grow at an increased rate. As these aquatic plants die, excessive oxygen is used in the decomposition process, which leads to oxygen deprivation and fish kills. This results in reduced animal populations in the lake, and the decomposition process releases more phosphates back into the water to feed even more plant growth. This dramatic increase in plant growth is called eutrophication and can make water unfit for human consumption.

A scientist wants to come up with a solution to help minimize eutrophication as a way to maintain the lake’s natural ecosystem without eliminating any of the lake’s native populations. Which of the following would be the best solution for the scientist to implement?
A.
treating all runoff with metal complexes that are poisonous to algae populations
B.
asking the farmers in the area to only use fertilizer on their crops when it is raining or windy outside
C.
spraying clay on the aquatic plants so that they sink to the bottom of the lake to decompose
D.
creating buffer strips around the lake using land vegetation to trap fertilizer runoff and prevent it from reaching the water

Answer 1

Answer: The best solution for the scientist to implement would be D, creating buffer strips around the lake using land vegetation to trap fertilizer runoff and prevent it from reaching the water. This solution would help to reduce the amount of organic substances, particularly phosphates, in the lake, which is the main cause of the eutrophication. Buffer strips would help prevent runoff from reaching the lake by trapping it in the vegetation surrounding the lake. This solution is environmentally friendly and would not harm any of the lake's native populations. Option A, treating all runoff with metal complexes that are poisonous to algae populations, could be harmful to the ecosystem of the lake and would not be a sustainable solution. Option B, asking farmers to only use fertilizer on their crops when it is raining or windy, may not be a practical solution as farmers need to fertilize their crops, and weather conditions may not always allow for it. Option C, spraying clay on the aquatic plants, may not be effective in the long run as it would not address the root cause of the problem, which is the excess nutrients in the lake.

Step-by-step explanation: