cycles, pollutants, and climate change Flashcards
What is chemical cycling in ecosystems?
Ecosystems need a contentious flow of energy AND chemical elements that can be recycled
“Chemical cycling describes systems of repeated circulation of chemicals between other compounds, states and materials, and back to their original state”
- geologic processes are common to all cycles but most also involve the atmosphere
What gets recycled in our ecosystem?
water, carbon, phosphorus
NOT ENERGY!!!!!!!!!!!!!
Nitrogen fixation by bacteria
- Plants need nitrogen but cant take it from the air
- bacteria in soil on the roots of leguminous plants take in Nitrogen gas (N 2) and makes ammonia and nitrates which plants use to make proteins for cell parts
(some bacteria lane ammonia and produce nitrates)
What organism fix Nitrogen?
Bacteria
what process fixes carbon?
Photosynthesis
What group fixes carbon?
photosynthetic organisms
Carbon cycle
Producers - plants take co2 from the atmosphere and make sugar by photosynthesis
Consumers - animals eat plants to get energy (respiration) from sugar and make proteins from the carbon (breathe out co2 as a waste product of respiration)
animals die and decomposers break down the carbon and other elements back into the soil and air for plants to use again
- Carbon enters the atmosphere as CO2.
- CO2 is absorbed by autotrophs such as green plants.
- Animals consume plants, thereby, incorporating carbon into their system.
- Animals and plants die, their bodies decompose and carbon is reabsorbed back into the atmosphere.
most of the sulfur that reaches the atmosphere is due to what human activities?
Burning coal, diesel, and metal smelting
Sulfur cycle
- lots of earths sulfur is stored in underground rocks/ocean sediments
- weathering/erosion releases sulfur
- combines w/ oxygen to make sulfate which is absorbed by plants
- sulfur can be released as a gas (sulfur dioxide) and form sulfuric acid rain when combined with oxygen and water
“Mineralization, oxidation, reduction, and incorporation”
phosphorus cycle
Phosphate compounds from broken down sedimentary rocks in the soil can be taken up by plants and, from there, transferred to animals that eat the plants. When plants and animals excrete wastes or die, phosphates may be taken up by detritivores or returned to the soil.
does not have a gas phase
what organisms take up phosphates?
plants
water cycle
Step 1: Evaporation - Water absorbs heat energy from the sun and turns into vapors
Step 2: condensation - At high altitudes the water vapor changes into very tiny particles of ice /water droplets because of low temperature.
Step 3: Sublimation - Sublimation is a process where ice directly converts into water vapors without converting into liquid water.
Step 4: Precipitation - The clouds (condensed water vapors) then pour down as precipitation due to wind or temperature change.
Step 5: Transpiration - Transpiration is a process similar to evaporation where liquid water is turned into water vapor by the plants. The roots of the plants absorb the water and push it toward leaves where it is used for photosynthesis. The extra water is moved out of leaves through stomata (very tiny openings on leaves) as water vapor.
Step 6: Runoff - runoff is the process where water runs over the surface of earth.
Step 7: Infiltration - Any water that doesn’t run directly to bodies of water or get quickly evaporated, will be absorbed by plants and soil, where it may be driven deeper to the earth.
water is needed as a major reactant for what process?
photosynthisis
biological magnification
toxic pollutants enter the ecosystem when they are absorbed or ingested by organisms. some substances accumulate in organisms tissues over time.
(move up through ecosystem)
substances become more concentrated as you make your way up the food chain
bioaccumulation
an increase in the concentration of a pollutant in a biological organism compared to its concentration in the environment
(how pollutants enter the food chain)
biomagnification
increase in the concentration of a pollutant as it passes from one trophic level to the next
travels from…
water to phytoplankton to zooplankton to small fish to large fish to the top predator
how things pass through food chain (energy and pollutants as you go up)
As you go up…
energy is lost
pollutants increase
Where do pollutants come from?
- coal burning power plants
- factories
- farms, lawns, and gardens
characteristics of pollutants (in order for biomagnification to take place a substance must be…)
- long lived
- fat soluble
- mobile
- biologically active
- effects organism in a negative way*
- only some substances bio-magnify
- most are water soluble and are excreted
- many breakdown quickly
- many aren’t biologically active
Mercury
Element (Hg)
changed to methylmercury by bacteria (most toxic form Ch3 Hg)
- form ingested by consuming fish, concerted in muscle tissue
sources of mercury
emissions from coal-burning power plants, metal processing, medical, and other waste
made bioavalible by bacteria (inorganic mercury that is biologically active)
Mercury in fish
fish absorbe mercury effectively
larger fish eat many small fish and build higher levels of mercury
some have been banned from consumption b/c of toxic risk
Impacts of mercury on wildlife
loons - steady diet of fish
- decrease in the number of chicks in areas high in mercury
- large concentration of mercury in eggs
great egrets - behavior of juveniles effected
deformities in developing animals
Mercury risk to people
- exposed by eating contaminated fish
- pregnant woman/children most at risk
- 60,000 children born yearly with neurological problems relate to mercury exposure
Persistent Organic Pollutants (POPs)
- also called organochlorines
- synthetic organic chemicals that persist in the environment and biomagnify through food webs
- poses a risk to human health and the environment
sources: pesticides, some plastics, plants, industrial chemicals, bleaching, burning garbage
Example: DDT, PCBs, Dioxin
Ban on POPs
in 1995 UN estimates 20,000+ subsistence have properties of POPs, Stockholm convention 2004, banned 12 worst (US signed in 2001)
Dirty Dozen
- PDT - pesticide
- PCBs - industrial
- Dioxin - waste
- Furans - waste
- Aldrin - pesticide
- Chlordane - pesticide
- Dieldrin - pesticide
- Endrin - pesticide
- HBC - pesticide/waste
- Heptachior - pesticide
- Mirex - pesticide
- Toxaphane - pesticide
Exposure to POPs
environmental - many will stay in soil/water for decades (slow to break down)
humans consume toxins via meat, dairy, fish, etc.
Humans and the environment
population growth
- 1850= 1 billion
- 2000= 6.25 billion
- 2025= 7.8 billion
acid rain
- precipitation PH<5.4
greenhouse effect
- chlorine breaking down ozone layer
ozone layer thinning
- absorbs high energy UV
deforestation
- loss of tropical forests
erosion/runoff
ground water contamination
