ELSS Flashcards
why do people need water?
essential resource for economic activity: used to generate electricity, irrigate crops (p/s), provide recreational facilities and satisfy public demand (drinking water, sewage disposal). in huge range of industries including food manufacturing, brewing, paper making and steel making, power generation
animals are mostly made up of water
sweat (evaporation of water from skin) regulates body tempo by cooling. this is an example of negative feedback to restore equilibrium
respiration in animals converts glucose to energy through reaction w/ oxygen to produce carbon dioxide and water
consume animals & plants
water is the medium used for chemical reactions in the body including circulation of O2 and nutrients
importance of water for plants?
require water to maintain rigidity (plants wilt when they run out of water)
needed to transport mineral nutrients from soil
transpiration of water from leaves’ surface cools plants by evaporation
respiration in plants converts glucose to energy through reactions with oxygen to produce carbon dioxide and water
water is the medium used for chemical reactions in the body including circulation of O2 and nutrients
plants manufacture own food through photosynthesis: in leaves, plants convert sunlight, water and CO2 to glucose, oxygen
importance of water for animals?
in fur-covered mammals, reptiles and birds, evaporative cooling is achieved by panting
consumers require plants as producers
respiration in animals converts glucose to energy through reactions with oxygen to produce carbon dioxide and water
water is the medium used for chemical reactions in the body including circulation of O2 and nutrients
sweat (evaporation of water from skin) regulates body tempo by cooling. this is an example of negative feedback to restore equilibrium
importance of water for climate?
water moderates environment: water vapour is an essential greenhouse gas which absorbs long-wave radiation from the Earth by helping to maintain average global temps about 15C higher than they would be otherwise AND clouds are made up of tiny water droplets and ice crystals, so reflect 1/5 of incoming solar radiation and decrease surface temperature= weather affected (distribute heat)
water helps create benign thermal conditions on earth e.g. oceans (71% of surface of Earth (and big carbon store)) moderate temps by absorbing heat, storing it and releasing it slowly. currents also created
water makes up what % of all living organisms?
65-95%
is crucial for growth, reproduction and metabolic functions
where is carbon stores on Earth?
in carbonated rocks e.g. limestone
sea floor sediments
ocean water (as dissolved CO2)
the atmosphere (as CO2 gas)
in the biosphere
importance of carbon
life is built on large molecules of carbon atoms e.g. proteins, carbohydrates, nucleic acids
used as an economic resource: fossil fuels (e..g coal, oil, natural gas) power the global economy
most manufactured goods are carbon-based.
oil is used as a raw material in manufacture of products e.g. plastics, paint, synthetic fabrics
agricultural crops and forest trees store large amounts of carbon available for human use as food, timber, paper, textiles e.t.c.
CO2 needed for p/s in plants to produce O2 and glucose
CO2 and CH4 are GHGs, so help to maintain suitable temperature for life (Goldilocks zone)
can determine acidity of rain/rivers/oceans (CO2=acidic) so can affect wetahering
CO2 is a pollutant so can affect human and ecosystem health
system definiton
a group of objects and the relationships that bind the objects together
open vs closed system in terms of carbon and water cycles?
on GLOBAL scale, cycles are CLOSED systems driven by Sun’s energy (external to Earth). only energy, not matter, crosses the boundaries
on SMALLER scales, materials as well as Sun’s energy cross system boundaries therefore they are OPEN systems. e.g. tree, drainage basin, forest ecosystem
equilibrium definition
long-term balance between inputs and outputs in a system
negative feedback definition
an automatic response to a change in a system that restores equilibrium
usually good
e.g. sweating
positive feedback definition
an automatic response to a change in a system that generates further change
usually bad
difference between stores and flows?
stores keep carbon/water e.g. ocean, tree
flows are wen water/carbon moves between stores e.g. precipitation, combustion
percentage of earth’s carbon stored in:
atmosphere
biosphere
ocean
lithosphere
0.5%
1.5%
27%
70%
how is carbon stored in the atmosphere?
as CO2 gas
also stored as methane (to a lesser extent)
what is the biosphere?
plants, animals and soil
how is carbon stored in the biosphere?
stored as organic molecules in living & dead plants & animals
in the soil it is stored as organic matter from dead plant material and the activity of microorganisms ( the decay process releases CO2 back to the atmosphere)
how is carbon stored in the ocean?
stored as dissolved CO2, but also as calcium carbonate in the shells of marine life which can fall to the sea floor and become marine sediment
much of the ocean carbon store is located at greta depths (only 4% found near the upper ocean surface)
what is the lithosphere?
rocks
SLOW CARBON CYCLE ( takes millions of year to be formed and be released & is irreversible)
how is carbon stored in the lithosphere?
stored as fossil fuels (coal, oil, gas)
stored in sedimentary rocks e.g. limestone and chalk
lithosphere=largest store of carbon
what are phytoplankton?
very small ‘plants’ in ocean which photosynthesise
how do phytoplankton play a crucial role in the carbon cycle?
‘producers’ so allow food chains to develop
photosynthesis removes carbon from atmosphere or carbon dissolved in the ocean
fall to the bottom of the ocean, undergo sedimentation and become lithified (become a rock) so enters slow carbon cycle
how are carbon-containing rocks produced?
- the hardening of mud (containing organic matter) into shale over geological time
- the collection of calcium carbonate particles from the shells and skeletons of marine organisms ends up in ocean sediments and is ultimately lithified to form chalk and limestone
how is carbon stored in the earth’s crust?
as hydrocarbons formed over millions of years from ancient living organisms under intense temperatures and pressure (fossil fuels e.g. coal, oil, gas)
3 ways that carbon can return to the atmosphere from the lithosphere
combustion of fossil fuels releases CO2 back to the atmosphere (anthropogenic)
volcanoes release huge volumes of carbon as CO2 and CH4 v quickly from magma in an eruption
exposed carbon-based rocks get weathered by atmosphere/water
processes in carbon cycle?
precipitation
photosynthesis
weathering
respiration
decomposition
combustion
sequestration
precipitation definition carbon cycle
this can dissolve atmospheric CO2 & this can form a weak carbonic acid. anthropogenic emissions of CO2 can increase the acidity of rainfall. this can have devastating effects on vegetation, human structures& fish stocks in lakes and rivers
photosynthesis definition carbon cycle
the process by which green plants & certain other organisms transform light energy into chemical energy. light energy is captured & used to convert water, CO2 & minerals into O2 & energy-rich organic compounds (incl. glucose)
respiration definition carbon cycle
the movement of oxygen from the outside air to the cells within tissues & the transport of CO2 in the opposite direction
weathering definition carbon cycle
the ‘in situ’ breakdown of rocks. when it involves the chemical action of rainwater, occurs bc the water is a weak carbonic acid, which is able to dissolve limestone and chalk by carbonation
decomposition definition carbon cycle
micro-organisms eg. bacteria and fungi break down dead organic matter, extracting energy & releasing CO2 into the atmosphere
combustion definition carbon cycle
occurs when organic material (containing carbon) reacts or burns in the presence of oxygen. the process will release CO2 into the atmosphere.
what are the 2 types of ocean sequestration?
physical (inorganic) pump
biological (organic) pump
does cold or hot water store more carbon?
cold water
describe the physical (inorganic) pump
involves the mixing of surface & deep ocean waters by vertical currents (creates more even distribution of carbon geographically and vertically) in the ocean.
initially CO2 enters the oceans from the atmosphere by diffusion. surface ocean currents then transport the water & its dissolved CO2 polewards where it cools, becomes more dense & sinks.
downwelling carries dissolved carbon to ocean depths where individual molecules may remain for centuries. eventually deep ocean currents transport the carbon to areas of upwelling. there, cold, carbon-rich water rises to the surface & CO2 diffuses back into the atmosphere
where does downwelling occur?
only a handful of places in the oceans e.g. North Atlantic between Greenland and Iceland
describe the biological (organic) pump
carbon is exchanged between the oceans & atmosphere through the actions of marine organisms
phytoplankton nr. ocean surface produce organic material when photosynthesising. whether they are consumed by animals in the marine food chain, or through natural death, carbon locked in phytoplankton either accumulates in sediment on ocean floor or is decomposed & released into ocean as CO2
other marine organisms e.g. molluscs, crustaceans extract carbonate & calcium ions from seawater to manufacture plates, shells, skeletons of CaCO3. most of this carbon-rich material ends up in ocean sediments and is ultimately lithified to form chalk and limestone
what % of all carbon fixation by photosynthesis takes place in the oceans?
50%
how much carbon is drawn from atmosphere by biological pump every year
about 50GT
largest store in carbon cycle?
sedimentary rocks
largest flow in carbon cycle? by how much?
oxidation of soil by 28Gt
what is meant by natural sequestration?
carbon being captured by and stored in natural environments e.g. oceans, trees, soil
residence times for carbon in slow carbon store?
150 million years
rate of transfer of carbon in fast carbon store
10-1000 times faster than those in slow carbon cycle
evapotranspiration definition
combined loss of water at the surface through evaporation and transpiration by plants
precipitation definition
moisture (rain, snow,hail) falling from clouds towards the ground
ablation definition
the loss of ice & snow, especially from a glacier, through melting, evaporation & sublimation
infiltration definition
the vertical movement of rainwater through the soil
run-off definition
the movement of water across the land surface
groundwater flow definition
the horizontal movement of water within aquifers
cryosphere definition
the frozen water part of the Earth system including frozen parts of the ocean e.g. waters surrounding Antarctica and Arctic
how does rain falling to the ground reach streams/rivers?
which is quicker?
infiltration (by gravity into soil and lateral movement or throughflow to stream & river channels)
overland flow (across ground surface either as a sheet or as trickles & rivulets to stream & river channels)
overland flow is faster
what is infiltration capacity?
how does this impact overland flow?
the maximum rate at which water, under the pull of gravity, soaks into the soil
when rainfall intensity exceeds infiltration capacity, overland flow occurs
where does groundwater flow move water to?
where soils are underlain by permeable rocks, water percolates deep underground. this water then migrates slowly through rock & joints as groundwater flow, eventually emerging at surface as springs/seepages
temperature in Amazon and why
constantly around 27C all year round bc on equator where suns rays are concentrated so constant growing season
v little seasonal variation bc on equator
how does precipitation vary annually in the Amazon?
convectional rain falls all year round, though most areas experience at least 1 drier period
highest precipitation in march 315mm
lowest in august 60mm
high average rainfall >2000mm w/ no proper dry season
on ITCZ (equator)= low pressure so air rises, cools, condenses so lots of convectional rainfall
what % of precipitation in the amazon is recycled?
what does this mean?
50-60% is recycled by evapotranspiraton
water losses form the amazonian basin result from river flow & export of atmospheric vapour to other regions. this loss is made good by an inward flux of moisture from the Atlantic Ocean
what is precipitation like in the amazon rainforest and why?
high average annual rainfall >2000mm
rainfall fairly evenly distributed throughout the year though short drier season occurs in some places
high-intensity, convectional rainfall
interception by forest trees is high (around 10% of precipitation)
intercepted rainfall accounts for 20-25% of all evaporation
low-pressure around equator->air rises-> cools and condenses->rain and clouds
what are rates of evapotranspiration like in the Amazon and why?
high rates of evaporation and transpiration due to high temps, abundant moisture and dense vegetation.
strong evapotranspiration-precipitation positive feedback loop sustains high rainfall totals
about 1/2 of incoming rainfall is returned to the atmosphere by evapotranspiration
most evaporation is from intercepted moisture from leaf surfaces
moisture lost in transpiration is derived from the soil via tree roots
what role does vegetation play in the water cycle in the amazon?
absorb and store water from the soil and release it through transpiration
3 physical factors affecting the amazon water cycle?
geology
relief
temperature
what is the geology in the Amazon and does this affects the water cycle?
how will this affect flood risk?
impermeable catchments (e.g. large parts of the Amazon Basin are an ancient shield area comprising impermeable, crystalline rock) have minimal water storage capacity, so there is rapid surface run-off and increased flood risk
permeable and porous rocks e.g. limestone and sandstone store rainwater, slowing run-off and reducing flood risk
what is the relief in the Amazon and how does this affect the water cycle?
how will this affect flows of water?
most of the Amazon Basin comprises extensive lowlands. in areas of gentle relief water moves across the surface (overland flow) or horizontally through the soil (throughflow) to streams and rivers
in the west the Andes create steep catchments w/ rapid run-off
widespread inundation across extensive floodplains e.g. the pantanal occurs annually, storing water for several months and slowing its movement into rivers
which of the 3 physical factors affecting amazon water cycle is most important? why?
temp will increase further in future due to CC so will have more significance (and changes daily and seasonally)
climate= most sig. bc it determines vegetation (by controlling water cycle e.g. trasnpiration), drives processes e.g. evaporation and precipitation
geology and relief are constant LT factors so are permanent but less sig.
but low-lying so may be flooded future bc of sea level rise cause by CC at mouth
how does deforestation affect flood risk?
topsoil not held together so increased soil erosion-> silts up rivers & decreases bankful capacity, increasing flood risk bc increased chance of peak discharge exceeding bankful capacity
minerals leached out of soil so it is infertile and trees cannot grow in the future
reduced interception so increased surface runoff and less infiltration into the soil-> quicker lag time, bigger peak discharge and more water to river more quickly, increasing flood risk
local vs downstream impacts of deforestation?
DOWNSTREAM: reduce interception increases surface runoff so increases risk of flooding
LOCAL: reduced evapotranspiration so reduced precipitation so drought
what happened in April 2014 in amazon?
Madeira river flooded w/ devastating impacts for Porto Velho community incl. 6o deaths, evacuations, cholera outbreaks, vast expanses of floodplains inundated
river reached record levels of 19.68m above normal
causes of April 2014 flooding in Amazon?
heavy rainfall
Santo Antonio and Jirau dams holding water for longer than natural flow
deforestation (less water storage in trees, soil, permeable rocks and atmosphere increase surface runoff)
how do runoff rates change due to deforestation?
converting rainforest to grassland increases runoff by a factor of 27
what percentage of rain falling on grassland goes directly into rivers?
50%
how can deforestation affect local climate?
rainforest trees= crucial part of water cycle (extract moisture from soil, intercept rainfall; releases to atmosphere by evapotranspiration) to stabilise forest albedo and ground temps
cycle maintains high atmospheric humidity, responsible for cloud formation and heavy conventional rainfall
deforestation breaks this cycle and can lead to permanent CC
how can deforestation affect regional climate?
projections of future deforestation in Amazonia predict a 20% decline in regional rainfall as the rainforest dries out and forest trees are gradually replaced by grassland
disruption of regional water cycle means forests 100s of kms downstream of degraded sites are affected too e.g. Manaus
are impacts of deforestation reversible?
yes
how much carbon can primary forest store per hectare
400 tonnes
selective logging can reduce the amount of carbon stored by….
50%
carbon stored in grassland and soya plantation (in comparison w primary forest)
16.2 tonnes/ha (25x less)
2.7 tonnes/ha (150x less)
how much carbon does the Amazon absorb each year?
2.4 billion tonnes
therefore is a major global reservoir of stored carbon
amount of carbon stored per hectare in trees, roots, and soil of amazon primary forest
large forest trees store about 400 tonnes C/ha above ground
further 40 tonnes C/ha in their roots
soil carbon stores average between 90 and 200 tonnes/ha
speed of exchange of carbon between atmosphere , biosphere and soil in amazon? why?
compared to other forest ecosystems, it is rapid
warm humid conditions ensure speedy decomposition of dead organic matter and quick CO2 release
rates of carbon fixation through p/s are high
physical factors affecting carbon cycle in amazon
vegetation
geology
temperature
organic matter in soil
how does vegetation affect the carbon cycle in the amazon?
carries out photosynthesis and respiration ( at accelerated rates due to high temps)
connects rainforest to atmosphere carbon stores
biggest store of carbonic TRF (60%)
400 tonnes of carbon per hectare
carbon sink of global importance
how does geology affect carbon cycle in amazon?
geology=carboniferous rocks (lots of carbon stored regionally in slow cycle)
rock si not exposed to weathering so this carbon doesn’t influence fast carbon cycle
no volcanic eruptions
in west nr andes, outcrops of limestone do occur
how does temperature affect carbon cycle in amazon?
consistent 27C
fast flows bc optimum growing conditions
fast decomposition and p/s
results in lots of vegetation
how does organic matter in soil impact the carbon cycle in the amazon?
leaf litter and dead organic matter accumulates temporarily at soil surface/ within rainforest soils. high temps/ humid conditions promote rapid decomposition by bacteria/fungi, emitting CO2 which is returned to the atmosphere and releasing nutrients to soil for uptake by tree-root systems
90-200 tonnes C/ha
significance of different physical factors in amazon carbon cycle?
temperature is the most significant factor bc it determines the rates of flows e.g. p/s, decomposition (so determines organic matter in soil)
determines abundance/ photosynthesis of vegetation
INTERDEPENDENCE OF FACTORS
geology=less important: not involved in fast carbon cycle
how does deforestation on a regional scale in the Amazon have global impacts?
LOCALLY: releases 1b tonnes of CO2 annually. less stores of carbon in vegetation and soils (soil erosion). soil infertility in LT. less flows of p/s
GLOBALLY: increased stores of atmospheric CO2 enhances CC
THEREFORE HARDER TO REVERSE
how does the Amazon water cycles allow the carbon cycle to operate so fast?
increased precipitation makes for ideal growing conditions, increasing rates of photosynthesis so increasing carbon storage in vegetation
how does the vegetation (i.e. photosynthesis) link the 2 cycles in the Amazon and how does this change diurnally?
more vegetation increases rate of p/s (ONLY DURING DAY), increasing vol. of carbon stored. this also helps recycle water via transpiration
vegetation is a store of water
vegetation intercepts water, decreasing surface runoff
how does deforestation (change in carbon stored) link the water and carbon cycles?
decreased carbon stores decrease water stores too
less evapotranspiration means less precipitation, decreasing runoff and the erosion of soil by water
if less precipitation, less p/s so less carbon stores
list the strategies to manage the water and carbon cycles in the Amazon
shifting cultivation
afforestation by the government
international agreements: UN REDD scheme
improved agricultural techniques ( agroforestry ad rotational cropping
what is shifting cultivation?
a traditional method of cultivation in tropicals rainforests which involves the rotation of land rather than juts the rotation of crops
it involves producing just enough food for survival and then moving on to new land
small areas of forest are cleared to provide land for farming: the soil here stays fertile for 10 years before farmers move on, clear new forest, move again and repeat this until first plot fertile again
how does shifting cultivation alter deforestation rates?
forest cleared for crops until soil exhausted of nutrients
therefore increases deforestation rates as new areas of land are cleared after several years while previous plot recovering
better than mass clearing of trees
positives of shifting cultivation
more sustainable for the environment than other forms of deforestation as area shave time to regrow
soil regains its fertility when farmers move onto new land
traditionally used by indigenous people
good for environment bc plants can regrow whilst farmers are elsewhere
limitations of shifting cultivation
trees are cut down to make space for farming
more efficient for farmers to clear larger areas at a time
not utilised as much bc people want economic growth and don’t care much ab the environment
not great for econ. progress; takes more time and planning
impacts on carbon cycle of shifting cultivation
creates less drastic change than deforestation
amount of p/s occurring decreases less than usual deforestation (clear felling)
less carbon stores removed at one time
less carbon released into the atmosphere
impacts on water cycle shifting cultivation
less significant change than deforestation
amount of precipitation decreases and surface runoff increases, but this is less sig bc only a few acres are cut down at a time so area can remain sheltered
AO2 effectiveness of shifting cultivation
effective as a small scale management strategy, what Amazon inhabitants have always done so already have knowledge and is in harmony w nature
less suitable for commercial farmers bc only small areas cleared at a time
doesn’t solve problem of deforestation, only mitigates
in EDCs such as Brazil, where eon dev. is prioritised, not best bc limits it
what is the REDD scheme?
provides payment to the Surui indigenous group for protecting the rainforest and abandoning logging
granting of carbon credits, which can be purchased bye international companies who have exceeded their annual carbon emission quotas
e.g. in 2013 Natura, a larte TNC, purchased 120000 tonnes of carbon credits from the Surui
how do REDD schemes alter deforestation schemes?
dramatically reduced deforestation rates in the territory during first 5 years of operation, but it was suspended in 2018 after discovery of large gold deposits, sparking a surge in deforestation (LT impermanence)
limitation= leakage (a reduction in carbon emissions in one area that results in increased emissions in another, such as curbing clear felling in one region drives farmers to clear fell in another)
impact of REDD schemes on water cycle?
REDD schemes prevent deforestation in the Amazon , so limit the impacts felt by the water cycle (unaffected)
BUT potential impermanence and difficulty of monitoring this strategy may mean that deforestation will occur in these areas in the future, so water cycle affected
impact of REDD schemes on carbon cycle?
before being suspended, project generated 300,000 carbon offsets certified under the Verified Carbon Standard (equal to removing 64000 cars from the road for a year), helping to meet the global imperative to sequester carbon
primary forest reminds: storing 400tonnes C per hectare (less combustion and felling of forest, so stored carbon not released)
limitations of REDD schemes as a management strategy
difficult to monitor accurately and reliably e.g. mining of gold too widespread to control
carbon calculations may be inaccurate
LEAKAGE: deforestation will increase elsewhere, affecting carbon and water cycles there
impermanence: LT viability of reduced emissions is heavily dependent on the forests vulnerability to deforestation
local scale projects
positives of REDD schemes as a management strategy?
created financial mechanism, so incentivises people in Brazil to reduce deforestation
relatively cost-effective: offsets cost less than $50 per tonne of CO2 (carbon capture offset costs $250-650 per tonne)
finances sustainable community development initiatives which generate income, support traditional practices (in harmony w nature) so enable LT dev, put value on land
what is afforestation?
planting trees in areas that haven’t recently has any tree cover, in order to create a forest
(e.g. desertified areas or areas used for agriculture)
acts as a method to reduce atmospheric CO2
reverses deforestation rates
provides habitat to local wildlife, creates wind breaks, supports soil health
impacts of afforestation on the water cycle
more flows of p/s
improves topsoil: nitrogen is fixed at a higher rate, neutralising soil pH
improvement in soil fertility and promotes ecosystem productivity
allows for more recycling of water via transpiration and evaporation from leaves
redues runoff
impacts of afforestation on the carbon cycle
more carbon is able to be stored so mitigates climate change
can reverse biodiversity losses and provide carbon sinks (absorb CO2)
increases carbon storage in biomass
interception decreases levels of surface runoff
increases soil fertility and amount of p/s so less soil erosion and more nutrients for decomposition
limitations of afforestation as a management strategy
depends on the quality of the soil
must suit the local environment: risk= use of non-local tree species e,.g. may use more water than the area has available
consider prevailing winds and direction of sunlight
takes 120 years for topsoil biomass to recover
not as good for wildlife as primary forest
overall effectiveness of afforestation as a management strategy
good in short term for reducing GHE and CC
take time to grow and reach optimal p/s levels
heavily relies on funding (NGOs, Govs)
hard to implement on a large scale
reduces flooding, so pos. social impacts too e.g. income generation
2 main diversification of agriculture methods
1.dark soils
2.agroforestry
what are dark soils
made from inputs of charcoal, waste and human manure
allow intensive and permanent cultivation, which would drastically reduce deforestation and carbon emissions
how do dark soils slow rates of deforestation
charcoal in the soils attracts microorganisms and fungi, allowing the soil to retain its fertility in the long term
this means that one area can be used to grow crops for multiple seasons and therefore limits the amount of open land farmers need to grow crops and decreases deforestation
what is agroforestry
doing some crop growth and leaving some trees
has lower yield of crops
but decreases soil erosion and maintains habitats
needs incentive
