What’s responsible for causing eutrophication in waterways?
A. Buring of fossil fuels
B. Fertilizers in water runoff
C. Pesticides in water runoff
D. Deforestation
The Correct Answer and Explanation is :
The correct answer is B. Fertilizers in water runoff.
Explanation:
Eutrophication is the process where excessive nutrients, particularly nitrogen and phosphorus, accumulate in water bodies, leading to an overgrowth of algae. This phenomenon can severely impact aquatic ecosystems by depleting oxygen levels and harming aquatic life. The primary cause of eutrophication is the runoff of fertilizers, which often contain high levels of nitrogen and phosphorus.
Fertilizers are commonly used in agricultural activities to enhance crop growth. However, when it rains, these nutrients are washed off the land and into nearby rivers, lakes, and streams. The high concentration of nutrients in the water encourages algae to proliferate rapidly in a process known as an algal bloom. These blooms can block sunlight, reducing the amount of light that reaches submerged plants, which are crucial for the health of aquatic ecosystems.
As the algae die and decompose, oxygen is consumed in large quantities by decomposer bacteria, leading to a condition called hypoxia or oxygen depletion. This lack of oxygen can result in dead zones, areas where most marine life cannot survive. Fish, in particular, are highly affected, as they depend on sufficient oxygen levels in the water.
While other factors can contribute to environmental degradation, such as burning fossil fuels (A), which causes air pollution, and deforestation (D), which can increase runoff and sedimentation, the primary driver of eutrophication is the fertilizer runoff (B). Pesticides in water runoff (C) can also harm aquatic ecosystems, but they typically affect the ecosystem through toxicity, not through the nutrient overload that causes eutrophication.
In summary, fertilizers are the key contributors to eutrophication because they provide an excess of nutrients that fuel algal blooms and disrupt aquatic life.