Biogeochemical Nutrient Cycles Flashcards

Eutrophication of lakes most commonly results from excess input of which two nutrients?

Answer: Nitrogen and phosphorus

Excess nitrogen and phosphorus from agricultural runoff fuel algal blooms that lead to eutrophication and oxygen depletion.

In the global carbon cycle, which process represents the largest annual flux of carbon from the land surface to the atmosphere?

Answer: Soil respiration and decomposition

Soil respiration and decomposition release more CO₂ annually than any other land-based process, though it is balanced by photosynthesis.

Which form of nitrogen is directly assimilated by most plants from the soil?

Answer: Ammonium (NH₄⁺) and nitrate (NO₃⁻)

Plants primarily absorb nitrogen in the inorganic forms of ammonium and nitrate through their roots.

The Haber-Bosch process has dramatically altered the nitrogen cycle by:

Answer: Industrially fixing atmospheric N₂ into ammonia for fertilizer

The Haber-Bosch process uses high pressure and temperature to convert N₂ and H₂ into ammonia, enabling mass fertilizer production.

What is the primary fate of phosphorus that erodes from land into the ocean over geological timescales?

Answer: It settles into marine sediments and eventually forms rock

Phosphorus carried to the ocean by rivers eventually settles into marine sediments, where it is incorporated into sedimentary rock over millions of years.

Which ecosystem type typically has the highest rate of decomposition and nutrient cycling?

Answer: Tropical rainforest

Tropical rainforests have the highest decomposition rates due to warm temperatures, high moisture, and abundant decomposer organisms.

Acid rain is primarily caused by atmospheric reactions involving which two pollutants?

Answer: SO₂ and NOₓ

Sulfur dioxide and nitrogen oxides react with water vapor in the atmosphere to form sulfuric and nitric acids, producing acid rain.