biogeochemical cycle (PP24) Flashcards
what is primary productivity
Quantity of biomass produced by primary producers
what is gross primary production (GPP_
Gross Primary Production (GPP): total quantity of biomass that a producer creates
Quantity of carbohydrates produced via photosynthesis
what is net primary production (NPP)
Net Primary Production (NPP): actual stored biomass available to consumers
what is the NPP formula
GPP minus biomass consumed by plant respiration (R)
NPP = GPP – R
in J/m2/year (Energy) or g/m2/year (Mass)
when is the NPP formula used?
Used when considering ecological efficiency
what is secondary productivity
Rate at which consumers convert chemical energy into biomass DIAGRAM IN SLIDES GO LOOK NOW
what is the anthropocene
Modern geological period – the age of humankind
Prefix “anthro” denotes human
what is the ecological footprint
Measures the land area needed to support a population living at a certain quality of life
Incorporates all resource need (food, energy, shelter, etc.)
Hallmark: land use & rise in greenhouse gas levels
what are the 4 important biogeochemical cycles?
nitrogen, oxygen, carbon, phosphorous
what is the main goal of the biogeochemical cycles
Cycling of important organic compounds in water and earth
what are biogeochemical cycles
Movement of chemical elements & molecules through biotic (“bio-“) & abiotic (“geo-“) components of an ecosystem
what is the water cycle and where is it found
Transportation of water via evaporation, transpiration, condensation, precipitation, & groundwater / surface water movement Found in: Oceans: 97% Ice (glaciers, polar caps): 2% Lakes, rivers, groundwater: 1%
know water diagram on slodes
LOOK AT NOTES
EXPLAIN the nitrogen cycle
Important ingredient of amino acids, nucleotides
Atmosphere = 80% N2
Atmospheric N2 ‘fixed’’ by bacteria to form ammonia (NH4+), usable by plants
Other bacteria convert waste nitrogen back to N2
explain phosphorus cycle
Important ingredient of nucleic acids, bones, & ATP
Important source of energy
Depends on rock weathering (slow process of erosion)
P trapped in rocks is released into soil → absorbed by producers → consumers → back too soil (decomposition)
what causes an increase of phosphorus in groundwater and soil? and are these natural or human impact
sewage, fertilizer and detergents
human
what can an increase of phosphorus cause ?
increase of biological growth
what is the human impact on the nitrogen cycle
↑ N in groundwater from sewage & fertiliser
Issues with drinking water
↑ in algae & cyanobacteria → ↓ O2 availability (anoxia) in lakes → ↓ fish (suffocation)
Intensive agriculture removes N from soil
Acid rain due to ↑ nitric acid
↓ soil pH & ↑ nutrient leaching (e.g. calcium)
what does an increase of nitrogen in water cause and what is the consequence of that
it causes an increase of growth of algae and cyanobacteria which therefore decreases O2 available in lakes (called anoxia) which therefore leads to the suffocation of fish.
what is a consequence of increase of acid raid due to the increase of nitric acid?
decrease in soil pH and increase in nutrient leaching
what is the duration of the short term carbon cycle
Takes place over the course of ~1 year
definition of sink and source
Sink: location that stores carbon
Source: location that releases carbon
what does the short term carbon cycle involve
Involves fluxes of carbon through different sinks
what is the process of the short term carbon cycle
Consider flow of carbon from organisms into the atmosphere & back again
Carbon is released into the atmosphere by respiration
Carbon is taken out of the atmosphere by autotrophs through photosynthesis
are carbon levels always constant or do they fluctuate
Carbon levels fluctuate over the course of a year
Must consider seasonal changes
Majority of plants found in the northern hemisphere (Eurasia, North America, much of Africa)
what is a natural cause for carbon level fluctuation?
seasonal changes
what seasons is there less photosynthesis (ie. an increase of atmospheric CO2 levels)?
Atmospheric CO2 levels increase during late fall & winter (less photosynthesis)
what seasons is there lower levels of CO2?
spring and summer
what is the duration of the long term carbon cycle?
Takes place over the course of thousands or millions of years
why is the long term carbon cycle more complex than the short term carbon cycle
More complex – need to consider carbon reservoirs
what is a carbon reservoir
Reservoir: area in which carbon is stored over long periods
a reservoir can be… and their definitions
Active: contribute to carbon cycles regularly & actively
Inactive: slower & more gradual influence on carbon movement
DIAGRAM ON SLIDES
is biomass an active or inactive reservoir and why
Biomass: active
Carbon within living organisms, in every cell
Not the same as the carbon released through respiration
is the atmosphere an active or inactive reservoir and why
Atmosphere: active
Primarily CO2
Approximately equal to carbon in biomass
is the soil an active or inactive reservoir and why
Soil: active
Carbon within topsoil & below permafrost
Approximately equal to carbon in biomass + atmosphere
is the ocean an active or inactive reservoir and why
Oceans: active
Much in the form of carbonate salts / mineral deposits
is sedimentary tock and sediment an active or inactive reservoir and why
Sedimentary rock & sediment: inactive
Largest carbon reservoir on the planet
Very slow to release
carbon cycle
LOOK AT DIAGRAMS ON SLIDES
what are the 5 steps to the long term carbon cycle
- Carbon released into the atmosphere (respiration + volcanoes)
- Some carbon removed from atmosphere via photosynthesis (added to biomass) or reacts with water (e.g. rain water) to form H2CO3
- H2CO3 enters water systems (oceans) & reacts with rock minerals to produce HCO3- & Ca2+ or CaCO3 (calcium carbonate) minerals that deposit on seabed
- Subduction of seabed (form deeper sediment) → create sedimentary rock carbon reservoir
- Carbon is ejected through volcanism or extracted through fossil fuel prospecting
what is the primary pump for the global carbon cycle>
Producers (plants/algae)
Total amount sequestered by producers is roughly equal to the amount released by volcanoes
true or false: Per year, photosynthesis can take more CO2 out of the atmosphere than is released through respiration
true
what powers the carbon cycle
‘Surplus’ CO2 powers the carbon cycle
true of false: Total amount sequestered by producers is equal to less the amount released by volcanoes
FALSEEE
Total amount sequestered by producers is roughly equal to the amount released by volcanoes
what are greenhouse gases and what is their function
Gases that create a buffer in the Earth’s atmosphere that allows solar radiation to enter the Earth’s atmosphere, but prevents heat loss from reflected/radiated heat
name the 4 main green house gases
Carbon dioxide (CO2) Methane (CH4) Nitrous oxide (N2O) Water vapour (H2O
explain the greenhouse affect
- rays of sunlight penetrate the lower atmosphere and warm the earths surface
- earth absorbs much of the solar radiation and degrades it to longer wavelengths (ie. infrared radiation which is heat) which rises to the lower atmosphere. some of the heat is released into space while some is absorbed by the greenhouse gases and admitted as inflamed, warming the lower atmos.
- as concentrations of greenhouse gases increase their molecules absorb and emit from infrared radiation ,which adds more heat
Without the greenhouse effect, Earth’s surface would be (blank) colder
Without the greenhouse effect, Earth’s surface would be ~30° colder
what is the current global average temp ?
Current global average temperature = 15°C
name a plant with a stronger greenhouse gas effect
Venus has a much thicker CO2 atmosphere, and a much stronger greenhouse effect (surface temperature 460°C)
what is responsible for most of the global warming from greenhouse gases and what is the rate at which its increasing
Carbon Dioxide–Responsible for 50-60% of global warming from greenhouse gases
Increasing 0.5% per year
what are the main sources of carbon global warming
Main sources–Fossil fuel burning and land clearing & burning
how long does co2 remain in the atmosphere
CO2 remains in the atmosphere for 50-200 years
true or false: the oceans are able to absorb all of the co2 we produce>?
false, they can absorb a lot of it but there are limits to how much it can absorb
what does chlorofluorocarbons do?
Chlorofluorocarbons (CFCs)– Contribute to global warming in the troposphere & deplete ozone in the stratosphere
what are the main sources of CFCS
Main sources–Leaking air conditioners & refrigerators, Evaporation of industrial solvents, Production of plastic foams (styrofoam), Aerosol propellants
true or false: carbon traps more heat than cfcs
false, cfcs *Trap 1,500-7,000 times as much heat per molecule as CO2
how long do cfcs stay in the stratosphere
Stay in the stratosphere 65-135 years
what is methane produced by?
Methane–Produced by anaerobic bacteria breaking down organic matter
Produced by–Swamps & wetlands, Rice paddies, Landfills, Intestines of grazing animals, Production of natural gas, Incomplete combustion of natural gas
true or false: methane traps more heat than co2?
true, *Each molecule traps 25 times more heat than a CO2 molecule
how long does methane stay in the atmosphere?
*Methane persists 9-15 years in the atmosphere
what can nitrous oxide do?
Nitrous Oxide– Can trap heat in the troposphere & can deplete ozone in the stratosphere
what are the sources of nitrous oxide?
Sources–Nylon production, Burning of biomass, Burning of nitrogen-rich fuels, Breakdown of fertilizers, Livestock wastes
what is the lifespan of nitrous oxide in the troposphere ?
*Life span in troposphere is 120 years
what are the factors contributing to the average global temperature?
Levels of greenhouse gases Changes in albedo Moderating effect of oceans Clouds & water vapour Air pollution / particulate concentration (e.g. volcanoes) Milankovitch cycles Changes in solar output
basic concepts affecting thee earths temp
Amount of sunlight Earth receives, Amount of sunlight Earth reflects, Retention of heat by the atmosphere, Evaporation & condensation of water vapor
what is albedo?
Ability of earth’s surface to reflect light, Melting of ice caps will decrease albedo, Positive feedback to global warming
does decrease in albedo cause negative or positive feedback to global warming?
positive
explain the moderating effect of oceans
oceans currently remove about 29% of CO2 in the atmosphere, solubility of CO2 in the ocean decreases with increasing temperature
explain the effect of clouds and water vapour on global temp
possibly as global temperature increases, more water will evaporate leading to more cloud formation which will reflect solar radiation and cool the Earth (negative feedback)
or clouds could have a warming effect by absorbing and releasing heat into the troposphere (positive feedback),
why are water vapour and water particles of little concern in terms of global warming?
Water vapor and water particles produce about 85% and 12%, respectively, of our total greenhouse warming, are of little concern because they are not increasing in the atmosphere as a result of human-induced processes
is air pollution expected to offset global warming, yes or no and explain
Air pollution is not expected to offset global warming because aerosols of various pollutants (which attract water molecules and can cause the formation of clouds that could reflect incoming sunlight back into space to counteract heating effects of increased greenhouse gases) are quickly washed out of the atmosphere and their inputs into the atmosphere are being reduced
what are milankovich cycles?
Periodic changes in Earth’s angle & orbit around the sun
what is the angle between earths rotational axis ands the orbital plane? what is its cycle>
Angle between Earth’s rotational axis & the orbital plane (obliquity) oscillates from 22.1° - 24.5°
41,000-year cycle
what is the Eccentricity of Earth’s orbit and what is its cycle?
Eccentricity of Earth’s orbit (between nearly circular & mildly elliptical)
100,000-year cycle
tue or false: milankovich cycles are Largely responsible for ice ages & warm periods across geological time
ture
why cant milankovich explain current climate fluctuations?
Much too slow to explain current climate fluctuations
are rising temperatures of the earth due to the sun?
no
explain temp vs solar activity
Planet has been hotter (geological time), but examination of solar activity does not show a good fit, & rate of temperature increase is worryingly rapid
LOOK AT SLIDES FOR DIAGRAM
