Biogeochemical Cycles – Carbon, Water, Nitrogen & Phosphorus

25 fill-in-the-blank flashcards covering key concepts, processes, and engineering relevance of the carbon, water, nitrogen, and phosphorus biogeochemical cycles.

Atoms cycling through biological, geological, and chemical processes are collectively known as __ cycles.

biogeochemical

Roughly __% of global photosynthesis occurs in the oceans, mainly by aquatic producers.

50

Organisms that break down dead matter and release carbon back to the environment are called __.

decomposers

Burning coal, oil, and natural gas releases stored carbon as __.

carbon dioxide (CO₂)

The water-cycle process in which water vapor cools and forms clouds is called __.

condensation

Water that seeps into the soil to replenish groundwater undergoes __.

infiltration

The direct change of ice or snow to vapor without melting is known as __.

sublimation

Bacteria that convert atmospheric N₂ into ammonia are termed __ bacteria.

nitrogen-fixing

The conversion of ammonia to nitrite and then nitrate is the process of __.

nitrification

Reducing nitrate back to N₂ gas by bacteria is called __.

denitrification

Nutrient overload in water bodies that leads to rapid algal growth is called __.

eutrophication

Unlike other cycles, the __ cycle has no significant atmospheric component.

phosphorus

The principal terrestrial source of phosphorus is the weathering of __.

rocks

Technologies that capture and store industrial CO₂ emissions are grouped under __.

carbon capture and storage (CCS)

Smart grids may reduce global greenhouse-gas emissions by up to __% by 2050.

10

Plasma-based nitrogen fixation seeks to lower the environmental impact of synthetic __ production.

nitrogen

Recovering phosphorus from wastewater sludge often forms the mineral __.

struvite

Fast surface flow of water that can cause flooding is termed __.

runoff

Long-term carbon storage as coal, oil, or gas results from __ and fossilization.

sedimentation

Clearing forests for farming reduces long-term carbon storage, weakening the __ cycle.

carbon

Decomposers converting organic nitrogen back to ammonia perform __.

ammonification

Designing controlled fertilizer systems to curb nitrogen runoff is a task in __ engineering.

agricultural

The phase change of water from liquid to vapor driven by heat is __.

evaporation

Plants absorb phosphorus chiefly in the form of __ ions.

phosphate

Carbon stored in fossil fuels re-enters the active cycle through __.

combustion