Question

Which of the following causes algae to grow? A) pesticides C) metals B) sediment D) fertilizers

Short answer

D) fertilizers

Step-by-step solution

Understand the Question

The question asks about the factors that lead to algae growth in water. Algae, like plants, require certain nutrients and environmental conditions to grow.

Analyze Each Option

Review each given option: A) Pesticides could potentially harm algae since they are designed to inhibit pests; C) Metals might contaminate water but not directly promote algae growth; B) Sediment might affect water clarity but does not provide nutrients; D) Fertilizers contain nutrients that encourage plant and algae growth.

Identify Key Factor for Algae Growth

Algae growth is primarily influenced by the availability of nutrients such as nitrogen and phosphorus. Fertilizers often contain these nutrients, which can lead to algae blooms if they enter water bodies.

Select the Correct Answer

Based on the analysis, fertilizers are the most likely cause of algae growth as they provide the nutrients necessary for algae to thrive.

Key concepts

Nutrient Pollution

Nutrient pollution occurs when too many nutrients, especially nitrogen and phosphorus, enter water bodies.
These nutrients are essential for plant and algae growth, but in excess amounts, they can cause problems.
Nutrient pollution is often a result of human activities:

• Agricultural activities release excess nutrients when fertilizers are applied to crops.
• Urban runoff can contain nutrients from lawn fertilizers and pet waste.
• Sewage and wastewater discharge often contain high levels of nutrients.

When these nutrients enter rivers, lakes, or oceans, they can lead to excessive algae growth.
This disrupts the ecological balance of water ecosystems.

Eutrophication

Eutrophication is a process driven by nutrient pollution that leads to the enrichment of water bodies with nutrients.
This process occurs naturally over centuries, but human activities have accelerated it significantly.
When water bodies become overloaded with nutrients:

• Algae grow rapidly, covering the surface of the water.
• This phenomenon is known as "algal blooms."
• As these algae die and decompose, they deplete the oxygen in the water.
• This leads to hypoxic conditions, often referred to as "dead zones," where aquatic life cannot survive.

Eutrophication can therefore reduce biodiversity and affect water quality, making it unsafe for human use and aquatic life.

Fertilizer Runoff

Fertilizer runoff is a major source of nutrient pollution leading to eutrophication in water bodies.
When fertilizers are applied to fields, not all of them are absorbed by plants.
During rainfalls or irrigation:

• Excess fertilizers can wash off agricultural lands and flow into nearby water bodies.
• This runoff carries with it significant amounts of nitrogen and phosphorus.
• These nutrients then enter rivers, streams, and eventually larger bodies of water like lakes and oceans.

Fertilizer runoff is a significant environmental issue as it contributes to harmful algal blooms and impacts the health of water ecosystems.

Water Ecosystems

Water ecosystems include a variety of habitats such as rivers, lakes, wetlands, and oceans.
These ecosystems are home to numerous plant and animal species.
Healthy water ecosystems are critical for:

• Maintaining biodiversity.
• Supporting fisheries, which are vital for food supply.
• Providing recreational opportunities such as swimming and boating.
• Regulating climate by storing carbon and cycling nutrients.

However, nutrient pollution and eutrophication pose significant risks to these ecosystems.
Algal blooms reduce light penetration and deplete oxygen, impacting all forms of aquatic life.
Protecting water ecosystems is essential for sustaining our planet's health and resources.