Question

Choose the correct statement(s).

1. Humans have altered the nitrogen cycle more than the carbon cycle
2. Humans have altered the carbon cycle more than the nitrogen cycle
3. Nitrogen and phosphorus runoff to nearshore marine ecosystems contributes to eutrophication, leading to oxygen depleted “dead zones”

		Only i.
		Only ii.
		Only iii.
		Both i. and iii.
		Both ii. and iii.

Answer 1

Answer is Both ii and iii.

• Human has altered the carbon cycle more than the nitrogen cycle by burning more fossil fuels, deforestation, etc. By the various activities humans have increased the Co​​​​​2 concentration in the atmosphere, changing the global climate and disrupting the carbon cycle more.

• Nitrogen and phosphorus runoff to nearshore marine ecosystems contributes to eutrophication, leading to oxygen depleted “dead zones” because too much nitrogen and phosphorus in the water increases the algae growth rate. This increased in algae harm water quality, food resources and habitats, and decrease the oxygen that fish and other aquatic life need to survive (hypoxia).