2.3: Biogeochemcial Cycles Flashcards
Human impact on carbon cycle case study: agriculture in the United States (background info)
Location: midwestern USA, Gulf of Mexico
Type of ecosystem: hardwood forest, prairies, coral reefs
Example food chain:
Indian grass -> prairie dog -> coyote
Reasons for human activity:
- Ideal conditions for corm, soybeans, wheat
- Fertile soil - millions of years of swamps/decay -> organic matter/nutrients in soil
- mostly flat land
- access to freshwater (Great Lakes)
- also use of fertilizers and monocropping (75% of agriculture in Midwest involve heavy equipment)
Human impact on carbon cycle case study: agriculture in the United States (impact)
Impact on energy and matter flow:
- Fertilizers affect mineral and nutrient cycling
- Vegetation removed -> reducing number of producers -> impact stability of food web
- Grazing animals impact plant biomass -> alter diversity and soil health
- Monocropping -> soil compaction/erosion -> loss in soil fertility/ + flooding/ +leeching
Potential impact on specific areas:
Fertilizers -> runoff down Mississippi River -> Gulf of Mexico
- nutrients -> Alger bloom (eutrophication) -> dead/hypoxic zones (low O2)
- habitat unavailable to marine organisms
Example of food web affected by flooding:
Oak tree -> acorn -> deer/fawn -> black bear
- fawn pushed out of habitat -> car accident
- excess soil moisture -> reduce O2 levels, damage root hairs, root system unable to absorbe water
Long term consequences:
- Decline in deer population
- vegetation loss, soil degradation
- decline in forest health
- displacement of people/health risks
- increased area of dead zones -> decline in biodiversity
Etc.
Human impact on carbon cycle case study: urbanization on the Amazon forest (background info)
Location: Brazil
Type of ecosystem: tropical rainforest
Example food chain:
Brazil nut tree -> squirrel monkey -> harpy eagle
Reasons for human activity:
Mining -> copper, tin, nickel, manganese, iron, gold
Deforestation -> wood used for furniture, paper, etc
Need for space -> build roads and infrastructures, farmland
Natural resources -> water, food, medicine
Human impact on carbon cycle case study: urbanization in the amazon rainforest (impact)
Impact on energy and matter flow:
- Loss of biodiversity
- dries up -> reduces flow of water
- decreased rates of photosynthesis
Potential impact on specific species:
Squirrel monkey/scarlet macaw:
- habitat loss -> prone to being hunted
- loss in food source
- die as a result of deforestation
- larger impact on food web
- decrease in overall population -> possible extinction
Long term consequences:
- serious climate impacts -> including carbon and water cycles
- increased pollution -> water/air quality decreases
- endangerment/extinction of many species -> decreased biodiversity
Human impact on carbon cycle case study: deforestation in the amazon rainforest (background info)
Location: Brazil
Ecosystem: tropical rainforest
Food chain example:
Mango -> ocelots -> spider monkey
Reason for human activity:
Cattle ranching - 80% of destruction caused by deformation
- land ended to raise cattle
- largest cattle exporter (1/4 of global cattle market)
Uncontrolled ranching/farming -> deforestation, fires, mercury contamination
Illegal gold mines
Logging outside designated areas
Selective logging of high value tree species
Human impact on carbon cycle case study: deforestation in the amazon rainforest (impact)
Impact on energy and matter flow:
- Decrease plant population (17% lost) -> decrease flow of producer energy/matter
- increase albedo (cooling) of land -> ecosystem adapted to high temp -> disrupt
- 50,000 species go extinct every year -> decrease flow of biological matter
- decrease soil quality -> decrease facility of growth
- less tree -> less CO2 absorbed -> increased greenhouse effect
Potential impact on specific species:
Indigenous people:
- decrease in 90 tribes since 1990 -> pushed out bc of deforestation
-> tribe were standing up for forests and wildlife
Giant Brazilian otter:
- habitat loss + exploitation -> only 1-5K left
- Food source depletion (contaminated)
Pygmy sloth:
- minerals + valuable resources -> scarce
- forced to travel large distances + floor to find food -> predation
Black spider monkey:
- habitat loss and hunting threats
- prefer mature tropical forest + don’t venture into disturbed habitat -> vulnerable to forest fragmentation
Example of web affected:
Complexity decreases
Producer decrease -> population of primary consumer decrease -> etc
Increased competition for food -> extinction of some species
Long term consequences:
Loss of species/biodiversity
Loss of vegetation -> instability in food web
Change in tropical climate -> increase in warmer climate
- increase chance of drought, wildfires, lengthy dry seasons
Change hydrological cycles
Human impact on carbon cycle case study: overfishing in the Mediterranean Sea (background info)
Location: Mediterranean sea
Type of ecosystem: coral reef
- damaged by fishing nets due to overfishing -> less food -> more vulnerable to bleaching
Reason for human activity:
High demand for seafood (local+global)
- profitable in the short term
Weak regulation and enforcement
Modern technology -> catch large amounts quickly
Not enough understanding of long term consequences
Subsidies encourage overfishing
Human impact on carbon cycle case study: overfishing in the Mediterranean Sea (impact)
Impact of energy and matter flow:
Overfishing -> disrupt food web, nutrient cycling, biodiversity -> imbalanced ecosystem, reduced energy flow
Potential impact on specific species:
Put more than 1/3 of sharks, rays, chimareas at risk of extinction
Example of web affected:
Phytoplankton + algae = base of food web -> eaten by zooplankton, small dish, crustaceans -> eaten by fish small sharks, coral, baleen whales
Long term consequences:
Loss of biodiversity
Decline in fish populations
Reduce food security
Loss of livelihoods for coastal communities
Human impact on carbon cycle case study: fossil fuels in the Great Barrier Reef (background info)
Location: Great Barrier Reef, Australia
Type of ecosystem: coral reef
Example food chain:
Algae -> giant clam -> box jellyfish -> sea turtle
Reason for human activity:
Large reserve of coal and natural gas
Use resources + import oil to meet needs
Uses: transport, houses, industries
Human impact on carbon cycle case study: fossil fuels in the Great Barrier Reef (impact)
Impact on energy and matter flow:
Energy: warming temp -> coral bleaching -> coral expel their algae
Algae = primary producers -> loss reduces energy available for the coral / food web
Matter: runoff carry sediment/pollutants
Bury coral reefs, reduce water quality
Pesticides, heavy metals, plastic can accumulate
Potential impact on specific species:
Coral:
Burning of fossil fuels -> increases water temp (climate change)
-> coral bleaching -> more susceptible to starvation and disease
Example of web affected:
Primary producer: energy production at base of food web decreases (less coral/phytoplankton)
-> fewer resources for higher trophic levels
Long term consequences:
Complete degradation of coral reef -> cannot support Maine life
Decrease in biodiversity, species, etc. -> lead to migration of certain species
Mitigation techniques case study: low carbon technologies- Xinjiang solar farm
Location: china, desert region near Urumqi
- sparsely populated
- rich in solar and wind resources
Worlds biggest photovoltaic solar farm
6.09 billion kilowatt/hour of electricity annually
200,000 acres of land
Produces enough power to power entirety of Papua New Guinea for a year
Substituting coal-fired power generation
- expected to reduce coal consumption by 110,00 metric tons each year
- decrease CO2 emissions by around 330,000 metric tons annually
-> 1 tree absorb 18 kg of CO2 per year -> emission reduction achieved equivalent to planting 17 million trees/ year
Mitigation techniques case study: reducing deforestation - REPLANT act
Location: national forest in the USA
National forest:
193 million acres of land
25% of carbon stored in the US forest ecosystem
Habitat for over 3,000 species
Mega fires fulled by climate change -> forest are being severely burned
- dry out forests
- less living trees for natural recovery
- damaged soil -> hard for new growth -> trees need to be planted by hand
- without reforestation -> prone to mudslides (destroy habitat + communities)
In response: provision in the bipartisan infrastructure law - REPLANT act (2021)
- pre-REPLANT: US forest service backlogged by 3.6 million acres
-> worse with increasing fires
- REPLANT got rid of $30 million cap on reforestation trust fund
-> was outdated (1980), didn’t account for labor costs, seed/seedling cost, etc
- also created urgency, modernized, used science/plant techniques to maximize results
First 2 years of REPLANT - backlogged reduced by 10%
Mitigation techniques case study: carbon capture - carbon sequestration in Norway and Switzerland
Governments -> international agreement to cut CO2 emissions
- enacting policies at local, regional, national levels
- goal = net zero by 2050
BUT reduced emissions not enough -> need to capture/sequester CO2
Carbon capture storage (CCS) -> CO2 emission captured at source -> prevent CO2 from entering atmosphere
Direct air capture and storage (DAC+S) -> removes CO2 directly from air
Climeworks (swiss) + Carbfix (Norwegian) -> remove CO2 from atmosphere and inject into basalt rock underground
- stored as solid carbonate materials
- climworks Orca DAC plant located in Iceland -> abundant renewable energy to power plant
Advantages:
Remove CO2
DAC tech advancing and becoming less costly
Governments implemented into net zero strategies -> funding likely
Disadvantages:
Small scale
Expensive
Energy intensive -> only viable with abundant renewable energy
Distraction from other methods
