APES Cycles and Soil Quiz

Human activities and the water cycle

increasing surface runoff through deforestation and urbanization, increasing evaporation due to climate change, decreasing groundwater recharge through overuse of aquifers and land-use changes, altering river flows with dams and diversions, and impacting precipitation patterns. 

dynamic equilibrium

while the Earth's water is constantly moving and changing forms (liquid, vapor, ice), the total amount of water in the system remains balanced over time because the overall rates of water input and output balance each other

biogeochemical cycles are driven by

solar energy and geological processes

primary sources and sinks of nitrogen

atmospheric nitrogen gas that is fixed by nitrogen-fixing bacteria and lightening

found in biomass (living organisms), organic matter in soil and sediments, and organic matter in marine sediments

nitrogen fixation

the process of converting atmospheric nitrogen (N₂) into ammonia (NH₃) or other nitrogen compounds, making it usable by living organisms for growth

nitrification

the biological process, carried out by microorganisms, that converts ammonia (a form of nitrogen) into nitrite and then into nitrate

ammonification

the biological process in the nitrogen cycle where microorganisms, such as bacteria and fungi, decompose dead organic matter and animal waste to convert organic nitrogen into ammonia and ammonium ions

denitrification

a biological process by which bacteria convert nitrogen compounds, particularly nitrates, into gaseous nitrogen (N₂) and release it into the atmosphere, often in anaerobic (oxygen-deprived) conditions

humans and the nitrogen cycle

the use of synthetic nitrogen and phosphorus fertilizers and fossil fuel combustions

limiting factor for aquatic ecosystems

the phosphorus cycle

respiration

Plants, animals, and microorganisms release carbon dioxide as they break down organic matter for energy

decomposition

When organisms die, decomposers (like bacteria and fungi) break down their organic remains, releasing CO₂ into the atmosphere

combustion

Natural fires, such as wildfires, burn organic matter and release stored carbon into the air

rock weathering

The weathering of carbonate rocks, like limestone, by carbonic acid in the atmosphere and soil releases CO₂

major carbon sinks

ocean, forests, and soils

CaCO3

inorganic compound of carbon that combines calcium, carbon, and oxygen

reason for changes in atmospheric carbon

the burning of fossil fuels (The combustion of coal, oil, and gas for electricity, manufacturing, and transportation)

continental weathering

the weathering of phosphate-containing rocks, like apatite, releases phosphorus into soils and freshwaters

atmospheric deposition

Mineral dust, volcanic ash, and other aerosols carry phosphorus particles from land to the ocean

human activities changing the carbon cycle

burning fossil fuels and deforestation

bacterial fixation

some bacteria converts atmospheric nitrogen gas (N2) into ammonia + ammonium

synthetic fixation

industrial process (harbor-bosch process) that chemically converts atmospheric nitrogen into ammonia into a form that plants can use (fertilizers)

transpiration

process where plants absorb water through roots + then release it as vapor through pores in leaves (stoma)

evapotranspiration

the combined processes which move water from the Earth's surface into the atmosphere. It covers both water evaporation and transpiration.

runoff

the water from precipitation that flows over the lands surface before going into rivers, lakes, oceans

infiltration

precipitation seeps into the soil + replenishes soil moisture

eutrophication

too much nitrogen and/or phosphorous + algal bloom

soil makeup

sand, silt, clay

sand

doesn't stick together
- rough, gritty
-largest particle
- lowest porosity
- highest permeability

silt

- smaller particle than sand, larger than clay
- smooth, soft, flour like texture
- highest porosity
-mid permeability

clay

- made from weathered rocks
- smallest particle
- sticky and slippery texture
- mid porosity
- lowest permeability

o-horizon

-organic
-uppermost soil layer composed primarily of fresh or partially decomposed organic matter, such as leaves, twigs, and other plant debris
-vital for providing nutrients to plants and plays a role in water absorption and soil structure

a-horizon

- topsoil
-high concentration of humus (decayed organic matter) and a high level of biological activity
- nutrient rich

b-horizon

- subsoil
-soil layer beneath the topsoil that accumulates minerals like clay, iron, and aluminum leached from the layers above during illuviation (being deposited and accumulated in lower soil horizons)

c-horizon

- weathered rock
- the deepest layer in a soil profile, consisting of partially or largely unweathered parent material, such as broken-down bedrock or sediment