APES Semester 1
CLIMATE CHANGE
1.4 Carbon Cycle
Closed system - matter can never be removed or created
i.e. Earth
Biogeochemical cycles - rely on essential earth elements and interactions between species and nature to use and reuse
Carbon cycle - movement of carbon across the Earth
Photosynthesis - CO2 from human activity and other natural processes is regulated and converted to oxygen
CO2 - greenhouse gas (important to mitigate effects of climate change)
Plants use CO2 in cellular respiration to convert glucose to ATP
When plants die, a decomposer will process the organic matter leaving the carbon in soil or nearby surroundings
Carbon sinks - retain/mitigate large amounts of carbon through storage (oceans/landfills)
Ocean absorbs CO2 from atmosphere
Sedimentation - CO2 combines with calcium ions in water to form calcium carbonate and stores carbon in the bottom of the ocean
Extraction of fossil fuels leads to climate change
Deforestation and declines in agricultural practices, fewer plants and crops exist to put carbon through photosynthesis
9.3 The Greenhouse Effect
Greenhouse effect - process by which energy from the sun is trapped in the form of heat by various types of greenhouse gasses (regulate temperature of Earth)
Light that reaches Earth - visible and UV
Main gasses - water vapor, carbon dioxide, methane, and nitrous oxide
Greenhouse gases have a high thermal retention property (Water vapor is the shortest, carbon dioxide is the longest)
GWP - Global warming potential - potential impact of GHG on climate change
Volcanic eruptions release a large amount of CO2
Natural sources of methane - wetlands, animal digestion, wildfires
Nitrous oxide is naturally produced through decomposition of organic matter and denitrification
CFCs are man-made chemicals that were used as aerosol propellants and now GHGs
Montreal Protocol - phasing out of CFC production (can stay 50-500 years in atm.)
Without greenhouse effect, earth would be much colder
9.4 Increases in the Greenhouse Gases
Increase in GHG can cause thermal energy to be trapped in troposphere
Increase in average global temperature
Industrialization of nations = more GHG (fossil fuels)
Melting of polar ice caps, ice sheets, permafrost, and glaciers contribute to rising sea levels
Increased temperature = water expansion = rising sea levels
Spread of disease with warmer temperatures in newer areas
Ocean acidification is caused with more CO2, affecting ability of some marine organisms to maintain shells and skeletons (reducing calcium access)
Extreme weather events become more common (drought, heatwave, flooding, hurricane)
Loss of biodiversity with warmer temperatures → displacement of species
9.5 Global Climate Change
Scientists can track climate by studying CO2 in ice cores
Earth naturally disperses heat from equator towards poles (oceanic circulation)
Climate change disrupts these patterns
Poles warm → snow and ice melts and permafrost → less solar radiation absorbed into space → poles warm
Positive feedback loop
Snow and ice melt → lack of habitat availability for organisms
9.6 Ocean Warming
As global air temps increase from GHGs, ocean temperature increases as well
Coral has a symbiotic relationship with algae (algae get place to live and get nutrients and provide coral with sugar)
Algae are very temperature sensitive
Coral bleaching occurs (El Nino)
Ocean warming contributes to sea-level rise and changes to currents
9.7 Ocean Acidification
Ocean acidification is caused by absorption of excess CO2 into the ocean
Co2 in seawater → carbonic acid → reduces pH of water → difficult for animals to maintain shells
More carbonic acid → less calcium carbonate used for shells and skeletons
4.9 El Niño and La Niña
El Nino = warming of Pacific Ocean between South America and north of Australia
Trade winds weaken, causing South America to have warmer waters
Higher precipitation in drier climates on the West Coast, but colder winters in southeast US
La Nina = cooling of Pacific Ocean between north of Australia and South America
Trade winds get stronger, pushing warmer water away from coastline
Upwelling → cold water is pushed up towards surface
Cooler temperatures on land, wet conditions in West; Southeast gets warm, dry conditions
Rapid climate change can cause more of these events → cause migration
BIOMES
1.1 Ecosystems
Ecosystem - particular location on Earth with interacting biotic and abiotic components
Biotic - living; abiotic - nonliving
Predator-prey relationship - one animal will kill and consume another animal
Predators (high trophic level) play an important role in regulating larger prey populations
Symbiotic relationship - at least one of the species benefits from the relationship
Mutualistic - both benefit; commensalistic - one benefits, one unharmed; parasitic - one benefits, one harmed
Competition - when organisms must share a limited resource
Resource partitioning - divide equally needed resources according to survival needs
keystone species - a species that plays a large role in its ecosystem despite being low in population
Removing keystone species might have devastating effects on an ecosystem
i.e. sea otters and kelp forests and sea urchins
Primary productivity - rate that solar energy is converted into organic compounds via photosynthesis over a unit of time
Net PP = Gross PP - Respiration loss
1.2 Terrestrial Biomes
Biome - geographic region that is characterized by a certain climate and diverse presence of plants and animals
Terrestrial biomes = biomes that exist on land (characterized by plant growth, temperature, and precipitation)
Aquatic biomes - characterized by presence of water (marine / freshwater)
TUNDRA - one of the coldest biomes on Earth (-40 to -10 degrees Fahrenheit)
No trees growing here, home to permafrost
BOREAL FOREST / TAIGA - large, coniferous forest biome in high latitudes of Northern Hemisphere
Long, cold winters and short, cool summers, tall trees,
TEMPERATE RAINFOREST - coastal biome with moderate temperatures, high precipitation (30 - 50 degrees latitude in both hemispheres)
Most species diversification in any biome, low nutrient soil due to frequent rainfall
WOODLAND / SHRUBLAND - SoCal, Australia, South America
12 month growing season, hot/dry summers, rainy winters, droughts/wildfires
TROPICAL RAINFOREST - warm/wet, near equator
Hot and humid, large amounts of rainfall, nutrient poor soil, most biodiverse
SAVANNA - dry and hot seasons with few green trees
Sub Saharan Africa, rich soil composition, hot spells, high biodiversity
SUBTROPICAL DESERT - very hot and very dry
No nutrients, very little biodiversity, very low precipitation
1.3 Aquatic Biomes
Freshwater biomes - lakes, ponds, rivers, and streams
Low salinity, variety of plant and animal life
Marine biomes - oceans, coral reefs, estuaries
High salinity, diverse plant and animal life
STREAMS AND RIVERS - constantly flowing freshwater
High amounts of oxygen, freshwater fish
LAKES AND PONDS
Lakes with high levels of productivity = eutrophic lakes; moderately productive = mesotrophic; oligotrophic = low levels of productivity
Productivity → levels of nitrogen and phosphorus
FRESHWATER WETLANDS
Very productive, saturated soils, lots of nutrients, prevent flooding and drought
SALT MARSHES
Found along the coast in temperate climates; located along estuaries
CORAL REEFS
Warm, shallow waters; sunlight can penetrate and promote photosynthesis
Most diverse marine biome, pollutants have created a problem (coral bleaching)
OCEAN
Photic zone - sunlight, photosynthesis
Aphotic zone - no photosynthesis
Benthic zone - no light, muddy
4.1 Tectonic Plates
Convergent boundary - two tectonic plates move toward each other
Subduction (more dense moves under less dense)
Oceanic → island arcs, oceanic trenches, volcanoes
Oceanic & continental → mountains, volcanoes
Divergent boundary → two tectonic plates move away from each other
Fault lines, rift valleys, seafloor spreading, volcanoes, earthquakes
Transform boundaries → two tectonic plates slide past each other
Earthquakes, heat/energy
4.6 Watersheds
Watershed - channel that concentrates runoff to the main discharge point (usually at the lowest point in the watershed)
Characteristics - size, length, slope, rate, present plant life, production, & efficiency
More runoff with steeper slopes (gravity)
Length → how long it takes runoff to reach discharge point
Type of soil → amount of runoff absorbed by soil
Sandy soil → more likely to be runoff
Fertile → more vegetation; more plants in a watershed = less erosion
Soil can filter water in a watershed
4.5 Global Wind Patterns
Heat and solar radiation is unevenly distributed because of earth’s tilt
Heat accumulates at equator, leaving poles without heat
Earth circulates warm air towards poles and moves cooler airs towards the equator
Hadley cells - 0-30 latitude; start with warm rising air and move away from equator
Ferrel cells - 30-60 latitude; cold, dry air of Hadley cells fall and Ferrel cells push warm air up
Polar cells - greater than 60 latitude; air cools and falls as dry air in poles
Coriolis effect- when an object in motion relative to a rotating frame of reference, it appears to curve in a certain direction
Plays a role in the way winds and ocean currents behave
Trade winds → winds do not travel in a straight line (they would if the earth wasn’t spinning)
4.7 Solar Radiation & Earth’s Seasons
Main source of energy → solar radiation (affects biomes during any season)
The angle of Earth’s tilt favors different seasons
At the equator, solar radiation hits surface straight on due to lack of curvature
Towards sun → hotter, away from sun → cooler
Equinoxes (spring, fall) → transition between summer and winter (approx. even days)
Solstices → highest and lowest points of sun throughout the year (longest/shortest days)
4.8 Earth’s Geography & Climate
Many factors that influence climate, some geologic and geographic
Sun - intensity of sun’s radiation can affect Earth’s climate
Earth’s orbit - shape of Earth’s orbit and proximity to Sun can affect Earth’s climate
GHGs - hotter, more abrasive/dangerous climates worldwide; increase likelihood of natural disasters
Volcanoes - when erupting, emits lots of atmospheric gasses
Ocean currents - because of ocean’s large heat capacity (store lots of heat without changing its own temperature)
Land masses - i.e. mountains can block movement of air masses
Rain shadow effect - one side of a mountain receives more precipitation than the other side
Windward → side with rain; leeward → drier side
ENDANGERED SPECIES
9.9 Endangered Species
Organisms are classified by IUCN by extinct, extinct in the wild, critically endangered, endangered, vulnerable, near threatened, and least concern
Reduction in population - population size decreases significantly
Geographic range - species has a restricted range or habitat
Population size - small population size in decline
Certain organisms are at more risk for extinction than others (difference in reproductive rate, adaptation ability to environmental change)
R-selected - high reproductive rate, quick rebound from population loss
Short life expectancy, low chance of survival
K-selected - low reproductive rate, long rebound from population loss
Long life expectancy, high chance of survival
Specialist species - specific niche and adapted to particular conditions
Vulnerable to environmental change
Generalist species - able to adapt to a variety of different climates, food sources, etc.
More resilient to environmental change
Overharvesting = most direct human influence on wild populations
CITES - developed to control and regulate the trade of threatened and endangered plants and animals
Endangered Species Act of 1973 - aims to protect and recover species in danger of extinction throughout US
Implements international CITES agreement mentioned above
3.1 Generalist and Specialist Species
Biomes create a range of conditions that create specific environments that, depending on species, can be liveable or unliveable
Factors to determine generalist or specialist: niche/adaptability, diet, location, tolerance
Generalist - broad niche that can easily adapt to many environmental conditions
i.e. raccoons can adapt easily to changes in weather or habitats
Specialist - narrow niche with incredibly specific needs to survive
Consistent climate, diet, etc.
More likely to suffer from natural disaster
i.e. pandas need a certain diet and habitat to survive
3.2 K-selected and r-selected species
K-selected and r-selected refer to different type of reproduction strategies
R-selected: high rate of reproduction and low investment in individual offspring
Adapted to environments with scarce resources, produce many offspring, low survival
K-selected: low rate of reproduction and high investment in individual offspring
Stable resources and produce small offspring with high survival
Biotic potential - maximum reproductive rate of a population in ideal conditions
K-selected = Type I and Type II; r-selected = Type III
Most invasive species are r selected
3.3 Survivorship Curves
Survivorship curves compare pattern of mortality between species
1.9 Trophic Levels
Lower trophic levels have higher populations than higher trophic levels
Ecosystems manage and regulate energy through trophic levels
1st, producers: produce their own food for themselves
2nd, primary consumers: only eat producers
3rd, secondary consumers
4th, tertiary consumers
Due to Law of Thermodynamics, energy is lost as we move up through trophic levels (less than 10% of energy is left as you move up trophic levels)
Mutualistic - both animals benefit from interactions
Commensalism - one benefits and the other is unaffected
Parasitic - one gets harmed and one benefits
Predator-prey relationship - one kills and consumes another animal
Competition occurs when animals must share a limited resource
1.10 Energy Flow and the 10% Rule
Law of conservation of energy - in a closed system, energy cannot be created or destroyed
Energy transformations always result in losses to waste heat (second law of thermo)
10% rule - 10% of energy is passed onto next trophic level
1.11 Food Chains and Food Webs
Food chain - how different organisms in an ecosystem depend on each other and how energy is transferred linearly
Food webs - observe trophic cascades
Trophic cascade - series of events in an ecosystem that occurs when a predator has an impact on the population of organisms that are lower in the food chain
Sea otters, kelp, and sea urchins
Negative feedback loop - when a system responds to change by trying to return to its original state or by attempting to decrease the rate at which the change is occurring
Prevent a single species from being too dominant
Positive feedback loop - change always continues to increase (ice caps melting)
Introduction of an invasive species
Usually cause negative effects
2.1 Introduction to Biodiversity
Biodiversity - variety of different species of plants, animals, and other living organisms that exist in a particular ecosystem
Genetic diversity - increases adaptability and resilience of a species
Genetic diversity can be lost with the bottleneck effect (Reduction in size of a population due to a factor decreasing # of individuals)
i.e. natural disasters, human activities, diseases
Species diversity - less vulnerable to collapse if exposed to extreme ecosystem change
Habitat diversity - variety of different habitats in a particular geographic area
Ecosystem richness - how many different species inhibit the ecosystem
Use Simpson’s Diversity Index to calculate richness (0 to 1)
Evenness - measure of how population sizes of each species compare
Ecosystem resilience - how quickly an ecosystem can recover after a disturbance
2.2 Ecosystem Services
Ecosystem services - naturally occurring benefits we obtain from ecosystems
Provisioning - products ecosystem provides (water, timber, food)
Regulating - benefits that ecosystems provide in terms of regulation (climate, water purification, pest control)
Cultural - recreational, aesthetic, and spiritual
Supporting - services that ecosystems provide that support the other three categoreis (soil formation, nutrient cycling)
ecosystem services contribute to human well-being and quality of life
Anthropogenic activity can damage/disrupt ecosystem services
2.3 Island Biogeography
As extinction increases, immigration decreases
Larger island and islands closer to mainland will have higher rates of immigration
Invasive species are common generalists that have few to no native predators, able to fill a broad niche
Darwin Finch and the Galapagos Islands - Evolution
Islands’ distance from mainland affected birds’ evolution
Birds adapted to islands and evolved away from their mainland characteristics
3.4 Carrying Capacity
Each population needs resources due to size, reproduction, and survivorship curves
There is a limit to the number of individuals an ecosystem can support
Carrying capacity (K) - max population size of a species that can be sustained given resources available in the environment
A population can overshoot carrying capacity, leading to negative consequences
Resource depletion, environmental degradation, increased competition, population crash (die-off)
9.8 Invasive Species
Invasive species - non-native species that is introduced to a new area and has the ability to establish a population and spread, causing harm to native ecosystem
Human activities have led to spread of invasive species
To prevent invasive species impacts, it’s important to prevent introductoion of invasive species
Physical removal - manually remove populations of invasive species
Chemical growth - pesticides to kill growth of invasive species
Biological control - introducing natural predators
Habitat modification - altering environment to make it less suitable for invasive
EXAMPLE: zebra mussels - reproduce quickly and outcompete native species for food and habitat
EXAMPLE: cane toads - introduced as a biological control method for pests, but became
invasive
8.8 Bioaccumulation and Biomagnification
Biomagnification - toxins/pollutants become more concentrated as they move up the food chain
Bioaccumulation - certain substances build up in the tissues of living organisms over time
Biomagnification can lead to accumulation of toxic substance in tissues of organisms at the top of the food chain
Reproductive failure, behavioral changes, death, etc.
EXAMPLE: DDT in pesticides passed to smaller fish and other primary consumers; these organisms were consumed by larger fish and DDT was passed on
EXAMPLE: methylmercury in seafood
POP - persistent organic pollutants (methylmercury)
DEMOGRAPHY
3.5 Population Growth and Resource Availability
Population growth - rate a population can grow at with given limitations by surrounding environments
How competition, biome, and self sufficiency leads to growth in a population
Exponential growth - population growth at intrinsic rate of increase (r)
Logistic growth - population growth exponentially until environment resistance (limited factors) make it reach its carrying capacity
3.6 Age Structure Diagrams
Age structure diagram - predicts population growth rate by a shape
Pre-reproductive age: 0-14; reproductive age: 15-44; post-reproductive age: 45+
Using an age structure diagram can help predict population increase, decrease, or stability
This graph shows population increase b/c majority of population is young:
This graph shows population stability b/c population has same amount of individuals in each age bracket
Suggests parents have access to reproductive education and can choose replacement level reproduction (2 children per couple)
3.7 Total Fertility Rate
Total fertility rate - avg number of children born to a woman in her reproductive age
TFR has been declining in recent years
TFR > in less developed countries; TFr > Replacement fertility rate (2.1)
Infant mortality rate - # of children that die before turning 1
High in developing countries due to lack of contraceptives, proper sex education, adequate medical training
Crude birth rate - number of births / 1000 people
Crude death rate - number of deaths / 1000 people
Emigration - number of people leaving the country (decreases population size)
Immigration - number of people entering a country (increases population size)
3.8 Human Population Dynamics
Factors that go into population increasing/decreasing - family planning, nutrition, education, jobs, development of the country
Industrialization - population growth → increase in sanitation, food, and medicine
Rule of 70 - 70 / population annual growth rate = population doubling time
Two types of factors that limit population growth - density independent and density dependent
Density independent - weather, climate, storms, fire, heatwaves, droughts
Density dependent - access to clean water, air, food availability, disease, and territory size
Annual percent change = [(births + immigrants) - (deaths + immigrants) x 100] / # of ppl
Population growth rate = (final population size - initial population size) / initial population
3.9 Demographic Transition
Stage 1 → high CBR, high CDR, low growth rate
Stage 2 → high CBR, lowering CDR, high growth rate
Stage 3 → lowering CBR, lowering CDR, lowering growth rate
Stage 4 → low CBR, low CDR, low/negative growth rate
Stage 5 → rising CBR, low CDR, stable/slowly increasing growth rate
OZONE LAYER
4.4 Earth’s Atmosphere
Earth’s atmosphere is mostly composed of oxygen and nitrogen
Nitrogen → denitrification; oxygen → photosynthesis
More gasses - methane (CH4), carbon dioxide (CO2), nitric oxide (N20), and ozone (O3)
Ozone absorbs harmful UV radiation from the sun
Reduces radiation that reaches the troposphere (beneath ozone layer)
Ozone layer prevents negative side effects from sun
Ozone layer was damaged by use of CFCs (chlorofluorocarbons)
Atmosphere → troposphere, stratosphere, mesosphere, thermosphere, exosphere
Troposphere - shallowest, temperature decreases as altitude increases, all weather occurs here
Stratosphere - composed of ozone layer, temperature increases as altitude increases
Mesosphere - temperature decreases as altitude increases
Thermosphere - increase in altitude, temperature increases due to large amounts of UV radiation from Sun
Exosphere - no weather occurs here, aurora borealis is here, satellites orbit this layer, molecules in the layer have low density
9.1 Stratospheric Ozone Depletion
Ozone absorbs incoming electromagnetic radiation from the sun, decreasing health effects like cancer and catarcts
CFCs (man-made chemical in aerosol) are highly reactive and bind with available oxygen needed to create ozone layer, preventing ozone layer healing
Ozone continuously splits apart and reforms as it absorbs EM radiation
O3 + electromagnetic radiation → O + O2
O + O2 → O3
A molecule of CFC can bond and destroy ozone
CFCl3 + EM radiation → Cl + CFCl2
CFC hit by EM radiation causes loss of chlorine atom
Cl + O3 → ClO + O2
Cl atom removes oxygen atom to make ClO molecule
ClO + O3 → Cl + 2 O2
9.2 Reducing Ozone Depletion
Montreal Protocol (1987) - phase out the production of chemicals responsible for the depletion of ozone layer
Encouraged HFCs that will break apart before reaching the ozone layer
One of the most successful international environmental treaties, although HFCs are highly contributable to climate change (GHG)
Clean Air Act: US law that regulates production and use of UDS (ozone-depleting substances)
AGRICULTURE
1.5 Nitrogen Cycle
Nitrogen cycle - process by which nitrogen is exchanged between the atmosphere, land, and water
Nitrogen is an important molecule for the growth and development of all living organisms
Nitrogen makes up 78% of atmosphere
Nitrogen fixation - nitrogen gas is converted into a form that can be used by plants and animals (ammonia (NH3) or nitrate (NO3))
nitrogen-fixing bacteria converts nitrogen gas into ammonia and then bonds with hydrogen ions to become ammonium
Nitrification - ammonia and other compounds becoming nitrite, and then nitrate (NO3)
Nitrification is bad for soil → pollution and algal blooms
Assimilation - nitrogen in its usable form gets absorbed by plant tissues
Ammonification - When these organisms die, decomposition occurs and organic nitrogen present in these organisms through nitrogen cycle reverts back into ammonium
Denitrification - bacteria takes nitrates and converts them into N20 and eventually back to N2
Nitrogen is common in fertilizers → overuse can have negative effects
1.6 Phosphorus Cycle
Phosphorus is in DNA, RNA, ATP
Found in PO4^3- (phosphate) and doesn’t undergo alteration throughout its cycle
When materials like rock are weathered, organic phosphorus is released into environment
Natural disasters, rain, and wind cause release of phosphorus
Phosphorus is transported between land and water through rain and runoff
Living organisms can absorb phosphorus for DNA production, etc.
Decomposition will release phosphorus back into environment
Sedimentation - excess phosphorus remains in rocks or soil at bottom of bodies of water
Geologic uplift - brings ocean layers up to become mountains
Anthropogenic sources → laundry detergents, synthetic fertilizers
Phosphorus runoff from synthetic fertilizers can accumulate in groundwater, throwing off balance of ecosystems
Eutrophication - body of water’s quality decreases due to excess buildup of nutrients → create problems for plant and animal life
8.5 Eutrophication
Eutrophication - excessive nutrients in water bodies, leading to algal blooms (bad)
Hypoxia - low oxygen levels in water due to decomposition of algae
Algal blooms - rapid overpopulation of algae (blocks sunlight, produces harmful toxins)
Dead zones - areas in water with low oxygen concentration, low level of life
Biodiversity loss - decline in variety of aquatic life due to eutrophication
Lakes can be classified by: eutrophic: high nutrients, prone to algae; oligotrophic: low nutrients, less algae; mesotrophic: moderate nutrients, moderate algae
Nutrients: nitrogen and phosphorus that promote plant (and algae) growth
Anthropogenic causes: agricultural runoff (fertilizers), industrial discharges (N2), untreated sewage
5.3 The Green Revolution
Green Revolution (1960s) - increase agricultural productivity
GMOs, new fertilizers (synthetic), pesticides, irrigation improvements (could deplete groundwater resources)
GMO (Genetically Modified Organisms) - altered for certain benefits like nutritional content/shelf-life
Pesticides kill good insects for agriculture and harm other wildlife
High-yield variety crops - crops that produce a higher yield
5.4 Impact of Agricultural Practices
Agricultural practices - techniques used to optimize farming practices
Environmental damage - practices cause significant harm to ecosystems
Slash and burn: Fire used to clear land → temporary fertile soil
Tilling: Soil turned to improve permeability
Causes soil erosion, disturbed soil microbiomes
Fertilizers: Overuse can damage crops, cause eutrophication
Pesticides: chemicals targeting unwanted organisms, but can harm non-target species
Cause human health defects (Cancer)
Soil erosion - removal of topsoil by water/wind, diminish soil quality and agricultural productivity
Heavy tiling can cause this
Monocropping - one species of crop only (causes decrease in biodiversity)
5.5 Irrigation Methods
Irrigation - uses water in several organized ways to promote healthy and efficient crop growth
Spray irrigation - distributes water from a central location using sprinklers
More efficient, less water loss
Flood irrigation - spreads water over field’s surface
Less efficient, environmentally friendly, more water loss
Furrow irrigation - utilizes trenches between crop rows
Inexpensive, water loss occurs
Drip irrigation - provides water directly to plant roots through perforated hose
Most efficient, not a lot of water loss, costly
Salinization - buildup of salts in soil as water evaporates (bad)
Aquifers - natural underground storage areas for groundwater
Transpiration - plants use to draw groundwater from roots up to their leaves
Permeability - ability of groundwater to penetrate soil
Runoff recharges surface waters, but can carry pollutants to water sources
Waterlogging - doesn’t allow water into pores, saturate soil, stunts/kills plants
Solution - drip irrigation, soil aeration
Saltwater intrusion - excessive pumping near coast lowers water table pressure, allowing saltwater to seep into groundwater
Cone of depression - forms when water table is lowered by pumping, depletes water
5.6 Pest Control Methods
Pesticide - spray/chemical used on crops to allow better protection against harmful species
Pros: eliminate pests from crops, protects against malaria and lyme disease, used against parasitic or invasive species
Cons: toxic to non-targeted species, high levels of contamination in soil and runoff → leaching, some cause cancer, expensive in abundance
Herbicide - targeted towards vegetation
Fungicides - used to control fungal infections (plants, seeds, or soil to prevent infections)
Rodenticides - designed to kill rodents (mice and rats)
Insecticides - kill insects/repel insects
4.2 Soil Formation and Erosion
Different soil horizons are created that have different properties and nutrients
Once a small layer of soil has been forms, moss and other small vegetation begin to grow → more and more soil horizons form and nutrients are added
O horizon (humus) → surface litter and other decaying matter
A Horizon (topsoil) → mixture of organic materials with minerals
E Horizon (Eluviated) → zone of leaching, nutrients from upper horizons moves to lower horizons
B Horizon (Subsoil) → zone of accumulation where minerals and nutrients accumulate
C Horizon (Parent Material) → material broken down to create the soil
Bedrock → solid rock that lies beneath parent material and soil
Soil can be washed away and eroded by wind/water
Can negatively affect water quality
4.3 Soil’s Composition and Properties
Water-holding capacity - amount of water can absorb given effects of gravity upon soil
Particle size, amount of organic matter play roles in this
Smaller particles → more water retention; larger particles → easier water flow
Porosity - how porous soil is (how much empty space)
Permeability - ability of nutrients and water to move down the soil horizons
Fertility - nutrient levels and how much vegetation it can support
Soil pH is how acidic/basic a soil is (acid from acid rain; cation exchange occurs when soil particles attract cations (positive charge))
Aeration - ability of soil to take in nutrients, water, and oxygen
Soil compaction - how compacted soil particles are (can affect porosity, permeability, and aeration)
Soil texture triangle ^ - identify soil using percentage of clay/silt/sand
Follow lines of each particle based on percent (sand → clay → silt)
5.7 Meat Production Methods
CAFOs (Concentrated Animal Feeding Operations): Intensive animal farming practices that maximize space use but contribute to pollution and animal welfare concerns
Free-range Farming: allows animals to roam freely; results in healthier animals, but expensive and less controlled waste management
Overgrazing: consuming vegetation faster than it regrows → soil erosion and desertification
Meat production impact → high economic value, but environmental degradation and health concerns
Manure Lagoons - large open storage pits for animal waste
Contains ammonia, hormones, antibiotics, e. Coli
Rain can flood lagoons and contaminate groundwater with runoff
5.1 Tragedy of the Commons
Tragedy of the Commons = when individuals overuse a shared resource, leading to depletion of destruction for all
Examples: ocean overfishing, air pollution, freshwater misuse, land degradation in national parks
Clean Air Act, Clean Water Act, Safe Drinking Water Act, BLM (Bureau of Land Management) → taxes, fines, criminal charges for pollution or shared resources
5.15 Sustainable Agriculture
Sustainable agriculture → prevent resource overuse
Contour plowing reduces soil disturbance by following natural land patterns
No-till minimizes soil preparation, reduces erosion in sand, dry soils
Windbreaks use trees and pushes to protect from wind erosion
Crop rotation alternates crops to replenish nutrients
Terracing creates flat areas on slopes to reduce runoff and erosion
Strip farming involves alternating planted rows with strips to manage nutrients and erosion
Green manure involves decomposing crop residue to enrich soil fertility
Adding limestone improves pH and replenishes Calcium
Rotating pastures prevents overgrazing and less compacted soil
5.16 Aquaculture
Aquaculture - farming of aquatic organisms like fish, aquatic plants, mollusks, crustaceans
Freshwater: ponds/tanks
Marine: saltwater cages
Efficient food production, creates habitats for healthy fish populations, aids in restocking endangered fish species, economic benefits to local communities
Waste management is hard, habitat destruction, disease spread due to proximity of species, genetic impact due to lack of biodiversity