Biogeochemical Cycles Flashcards

Which of the following best describes a 'sink' in a biogeochemical cycle?

Answer: A reservoir that accumulates more of a substance than it releases

A sink is any reservoir that absorbs and stores more of a substance than it releases over a given time period.

What happens to the carbon stored in peat bogs when they are drained and burned?

Answer: It is released as CO₂, contributing to atmospheric greenhouse gases

Draining and burning peat bogs releases centuries of stored carbon as CO₂, making them significant sources of greenhouse gas emissions.

Which step in the nitrogen cycle converts ammonium (NH₄⁺) into nitrite (NO₂⁻) and then nitrate (NO₃⁻)?

Answer: Nitrification

Nitrification is a two-step aerobic process performed by bacteria like Nitrosomonas and Nitrobacter that oxidizes ammonium to nitrite then nitrate.

How does the hydrological (water) cycle interact with the phosphorus cycle?

Answer: Precipitation and runoff transport dissolved phosphate from land to aquatic systems

Precipitation and surface runoff erode and transport phosphate ions from soils and rocks into rivers, lakes, and eventually the ocean.

Eutrophication of lakes is most directly caused by excess input of which nutrients?

Answer: Nitrogen and phosphorus

Excess nitrogen and phosphorus from agricultural runoff fuel algal blooms in lakes, leading to oxygen depletion when algae decompose.

What is the primary pathway by which carbon moves from the atmosphere into terrestrial ecosystems?

Answer: Photosynthesis by plants and other autotrophs

Photosynthesis is the main biological pump that removes CO₂ from the atmosphere and incorporates it into organic molecules.

Which biogeochemical cycle is most closely linked to the formation of acid rain?

Answer: The sulfur cycle

SO₂ emissions from fossil fuel combustion react with water vapor to form sulfuric acid, which falls as acid rain.