Biogeochemical Cycles Flashcards
Nutrients move through ecosystems in ______, also known as ______
nutrient cycles, biogeochemical cycles.
Elements or molecules travel through the atmosphere, hydrosphere, lithosphere, and biosphere in dynamic equilibrium.
Nutrients move from one ____, or ____, to another for varying amounts of time, called the _____.
reservoir, pool, residence time
When a reservoir releases more materials than it accepts, it is called a _____.
source
When a reservoir accepts more materials than it releases, it is called a _____.
sink
_____ is the rate at which materials move between reservoirs.
Flux
The _____ describes the routes that carbon takes through the environment.
carbon cycle,
Carbon is found in all organic molecules—carbohydrates, fats, and proteins, which make up living organisms.
_____ (plants, algae, and cyanobacteria) pull _____ out of the air and use it to produce sugars like _____
Producers, carbon dioxide, glucose (C6H12O6).
____, _____ consume organic molecules and release some of the ____ as carbon dioxide.
Autotrophs, consumers, and decomposers, carbon
As aquatic organisms ____, their remains may settle in _____ in ocean basins or______
die, sediments, freshwater wetlands.
Converted over time to _____ into oil and skeletons into sedimentary rock like ____
soft tissue sediments, limestone
The oceans are the _______ of carbon, dissolving carbon dioxide, _____ and _____.
second-largest reservoir, carbonate ions (C O3 2−), bicarbonate ions (H C O3−).
_____ is the largest reservoir in the carbon cycle.
Sedimentary rock,
Released during uplift, erosion, volcanic eruptions, or the burning of fossil fuels
Today’s _____ reservoir is estimated to be the largest in the past _____
atmospheric carbon dioxide, 800,000 years.
Combustion of fossil fuels (a carbon sink)
Decrease of surface vegetation
Some of the excess ___ is being absorbed by the oceans, causing it to become more ____.
C O2, acidic
About 2.3–2.6 billion metric tons of released fossil fuel C O2 is ____ for.
unaccounted
Nitrogen is an essential ingredient in ____
D N A, R N A, and proteins.
_____ makes up 78% of the atmosphere, but is chemically inert and cannot leave the atmosphere without assistance.
Nitrogen gas (N2)
Under the right conditions, nitrogen can become biologically active and enter the biosphere and lithosphere, a process called _____
the nitrogen cycle.
In _____, inert nitrogen gas becomes biologically available by combining with hydrogen to form _____, whose water-soluble ions of ______ can be taken up by plants.
nitrogen fixation, ammonia (N H3, ammonium (N H4+)
The intense energy of lightning strikes can also fix nitrogen.
_____ convert nitrogen gas into ammonia.
Nitrogen-fixing bacteria
The bacteria form nodules on plant roots, absorbing sugars from the roots in exchange for nitrogen fixation.
Found in legumes, such as soybeans
Other bacteria perform a process called _____, which converts ammonium ions into nitrite ions (N O2−), then into nitrate ions (N O3−), which plants can directly take up.
nitrification
These ions are also added to the soil through the use of fertilizer.
Consumers obtain nitrogen by ingesting plants or other animals, while _____ obtain and release nitrogen from dead and decaying matter.
Consumers, decomposers
______ will then convert nitrates back into nitrogen gas.
Denitrifying bacteria
Nitrogen fixation has historically been a ______, a step that limited the flux of nitrogen out of the atmosphere.
bottleneck
The _____ enabled people to artificially fix nitrogen, greatly enhancing agriculture.
Haber-Bosch process
Humans have effectively doubled the rate of nitrogen fixation on Earth.
Runoff can cause excess nitrogen to enter waterways, causing ____.
eutrophication
_____ releases additional nitrogen into the atmosphere.
Burning fossil fuels
Phosphorus is a key element in many organic molecules, including _____
D N A, R N A, and A T P.
The biggest phosphorus _____ are rocks, soil, sediments, and the oceans.
sinks
Very little is in the atmosphere.
The processes that move phosphorus from these sinks to living matter are called the _____
phosphorus cycle.
Weathering of rocks releases ____ into water.
phosphate ions (P O4−)
These phosphates precipitate into a solid form, sink to the bottom of bodies of water, and re-enter the lithosphere as sediments.
Aquatic organisms take up ____ directly from surrounding waters.
phosphates
Terrestrial organisms take up ____ from soil water through their roots.
phosphates
Phosphates are passed through the food chain and eventually returned to the soil by decomposers.
Like nitrogen, the runoff of phosphorus ____ its concentration in surface waters.
increases
Water is the medium for all _____, and it plays key roles in nearly every environmental system.
biochemical reactions
Carries nutrients, sediments, and pollution
Returns atmospheric pollutants to the surface through rain or snow
The ____ summarizes how water flows as a solid, liquid, and gas through our environment.
hydrologic cycle
The oceans are the main reservoir (97%) for water.
Only about 3% is fresh water, and two-thirds of that is frozen in glaciers, ice caps, and snowfields.
_____ converts water from a liquid to gaseous form, taking it to the atmosphere.
Evaporation
Increased by warmth, wind, and exposure
____ is the release of water vapor by plants through their leaves.
Transpiration
Dissolved substances are left behind.
Water returns to Earth’s surface as _____ when it condenses into rain or snow.
precipitation
Most of it flows as runoff into surface waters.
Some precipitation and surface water soaks down through soil and rock, becoming _____.
Groundwater recharges underground ____.
groundwater
aquifers
The upper limit of groundwater in an aquifer is called the _____
water table.
