Chapter 21: Movement of Elements in Ecosystems (water, carbon, nitrogen, phosphorous) Flashcards
dead zone
aquatic ecosystems that experience algal blooms + large animal die-offs
- Mississippi river flows into Gulf of Mexico every summer
direct effects of summer algal blooms
some algae or cyanobacteria produce toxins when the bloom
indirect effects of summer algal blooms
phytoplankton bloom and die
- Bacteria consume dead biomass and use lots of O2
- Aquatic life dies from oxygen deprivation
causes of summer algal blooms
nitrogen + phosphorous from fertilizers run-off into streams/rivers, phosphorous from detergents and sewage cause rapid algal growth
- Along with warm temps
required nutrients from biotic and abiotic ecosystems
Hydrogen, oxygen, carbon, nitrogen, and phosphorous
nutrient / biogeochemical cycle
path an element takes as it moves from abiotic systems through living organisms
- via assimilation, consumption, and decomposition
Organisms need 7 major nutrients
nitrogen, phosphorous, sulfur, potassium, calcium, magnesium, and iron
what controls the rate of nutrient cycling?
decomposition of detritus limits the rate at which nutrients move through an ecosystem.
what controls decomposition rate
temperature and moisture
the hydrologic cycle
movement of water through ecosystems and atmosphere
hydrologic cycle components/transfers
evaporation, transpiration, and precipitation
97% of earth’s water is in ___
oceans
Human impacts on the Hydrologic Cycle:
- Roofing/pavement/concrete create surface runoff (can’t hold water like soil)
- Logging (removing trees) decreases precipitation and evapotranspiration
- Draining aquifers quicker than they can be replenished
- Global warming causing temperature rise increasing water evaporation
all organisms are composed of ___
carbon
6 transformations of the carbon cycle
photosynthesis, respiration, sedimentation and burial, extraction, and combustion
nutrient loss from leaching and water transport is balanced by inputs of ___ from the ___ and from ___ of bedrock under the soil
nutrients from the air
the weathering of bedrock
weathering rates can be determined by
measuring nutrients entering a system from rainfall and leaving a system by leaching
- the balance b/w loss and gain of nutrients
watershed
area of land draining into a single stream or river
Photosynthesis and respiration do what?
take CO2 from air and water –> carbohydrates, release some CO2 back
Human impacts on the carbon cycle:
- Extraction and combustion of fossil fuels
previously, CO2 ppm had never surpassed ___, but now its over ___
300 ppm, 405 ppm
Nitrogen is important for:
building proteins and nucleic acids for DNA
Nitrogen fixation
converting atmospheric N2 –> forms producers can use
o N2–> NH3 (ammonia) or NH4+
o Occurs in 3 ways: cyanobacteria/4 types of bacteria, lightening/rain, and production of fertilizer
Nitrification
converts NH4+ or NH3 –> NO2- –> NO3-
- release potential energy by bacteria
- transforms into usable nitrogen
autotrophic river
if primary production exceeds decomposition
heterotrophic river
if decomposition exceeds primary production
- occurs in most streams
Nitrogen Assimilation
producers take up nitrogen and incorporate it into their tissues
- Primary consumers eat producers and assimilate and excrete nitrogen
Nitrogen Mineralization / ammonification
mineralization: breaking down organic compounds into inorganic compounds
ammonification: animals excrete urea, uric acid, or ammonia; decaying plant and animal material is also broken down by ammonifying bacteria into NH3+
Denitrification
process of converting nitrates into nitrogen gas, returns nitrogen into the atmosphere; done by bacteria
o Highly soluble in water
5 major transformations in the nitrogen cycle
nitrogen fixation, nitrification, assimilation, mineralization, and denitrification
plants need ___ nutrients
dissolved
Human impacts on the nitrogen cycle:
Humans have double nitrogen put into terrestrial ecosystems by:
o combustion of fossil fuels
o production of nitrogen fertilizers
o planting nitrogen-fixing crops
__% of all plant matter produced in a year is not consumed by herbivores but it is ultimately decomposed
90
leaching removes ____% of soluble substances from organic matter
10-30%
phosphorous is used for:
bones, scales, teeth, DNA, RNA, and ATP
___ is a common limiting nutrient in aquatic and terrestrial ecosystems
phosphorous
plants take up phosphorous from ___ and animals eliminate excess through ___
from soil or water
- through urine
Eutrophication
increase in productivity of aquatic ecosystems
Cultural eutrophication
increase in productivity of aquatic ecosystems caused by human activities
4 ways for the breakdown of plant matter in a forest:
soluble minerals leach out of organic matter, detritivores consume organic matter, fungi break down the woody and leafy components, bacteria decompose everything
___ of organic matter influences breakdown rate
chemical composition
Because weathering is a slow process, primary production relies on regeneration of nutrients from the break down of
_____.
detritus
what factors influence the rate at which nutrients are exported from ecosystems?
precipitation, plant life levels, decomposition
In terrestrial ecosystems, nutrients regenerate close to ___________.
the location where they are taken up by producers
In aquatic ecosystems, nutrients regenerate in ________.
the sediments, which are often far from the surface waters where producers live.
nutrients that life need (each has a cycle)
CHNOPS- carbon, hydrogen, oxygen, phosphorous, sulfur
evapotranspiration
evaporating and moving from liquid to gas through transpriation
how do plants get carbon?
photosynthesis
how is carbon released into the atmosphere?
respiration releases it as CO2
how is carbon stored?
in rocks- extracted for fossil fuels; combustion releases it back into atmosphere
how is nitrogen returned to the atmosphere?
denitrification
weathering and erosion does…
move phosphorus into soil/water supply
how is phosphorous returned?
excretion and decay; returns to rocks
- doesn’t include atmosphere = slow
sulfur cycle
- moves from ocean to atmosphere through conversion by bacteria
- assimilated through atmosphere, back to oceans
- some also stored in rock
reservoirs of CO2
atmosphere, fossil fuels, organic material
assimilation of CO2
photosynthesis and animal consumption
release of CO2
respiration, decomposition, combustion
bacteria assimilate and release __
nitrogen
phosphorous cycle
plants take in phosphate through roots, animals eat plants, released by excretion and crop residue
___ is lost when crops are harvested
phosphorous and nitrogen (fertilizer)
___ is not found in the atmosphere
phosphorus
where is phosphorous stored and how is it released?
rocks; released through weathering w/ rain, travels to soil for uptake by plants
how is phosphorous returned to the environment?
mineralization
In terrestrial ecosystems, nutrients regenerate…(location)
close to the location where they are taken up by producers
In aquatic ecosystems, nutrients regenerate/accumulate….(location)
in sediments, often far from the surface waters where producers (e.g., phytoplankton) live
Terrestrial ecosystems commonly experience ____ decomposition, whereas aquatic ecosystems commonly experience ___ decomposition.
- aerobic decomposition
- anaerobic decomposition (much slower)
who’s responsible for decomposition in aquatic ecosystems?
bacteria
material in which organic matter is made out of effects ____
decomposition rate
Stratification occurs when…
- surface waters warm while deep waters remain cold
- less dense freshwater from rivers flows over more dense ocean saltwater
vertical mixing of water occurs when…
the temp of surface water changes to match the temp of deep water
vertical mixing in oceans occurs when
evaporation makes surface waters saltier than deep waters
- mixing can bring nutrients up to algae
5 major nutrient cycles
water, carbon, nitrogen, phosphorus, sulfur
clouds dump their water when…
they get colder
what forms sediments?
carbon (calcium carbonate)
where is the most accessible carbon (largest reservoir)?
the ocean
where is the most stored carbon?
the lithosphere
The vast majority of molecular nitrogen (N2) in the atmosphere is unavailable to plants bc…
they can use nitrogen only in the form of
(NO3) or nitrates
Rhizobium (Rhizobia)
associate w/ legumes (form nodules on roots) to provide the plant w/ nitrogen
phosphorus does not have a ____ phase
gas (only dust form- PO4^3-)
in oxygenated waters, phosphorous precipitates after binding w/ _____
calcium and iron
in low oxygen conditions, irons binds with ___ instead of phosphorous.
sulfur (makes phosphorous more available)
2 factors responsible for the human impacts on ecosystems
- the rapid increase in human population
- the rapid increase in human resource use
