AP Environmental Science: Unit 8 - Aquatic & Terrestrial Pollution
8.1 Sources of Pollutants
point vs non-point
point source - single identifiable source (you can āpointā to it)
waste discharge pipe, smokestack, the derailed train in ohio, CAFOs (ammonia)
should know about the BP oil spill (see 8.2)
non-point source - diffused source, entering the environment from multiple locations
urban runoff (motor oil, phosphates from car wash, and detergents)
pesticide spraying
key points!
estuaries and bays are polluted by many non-point pollution sources from the large watersheds that empty into them
identify specific pollutants, donāt just say the word āpollutionā
8.2 Human Impacts on Ecosystems
range of tolerance
organisms have a range of tolerance for abiotic factors in their habitat
also applies to pollutants that are released into ecosystems by human activities
coral reefs
coral reef = mutualistic relationship between coral and photosynthetic algae (zooxanthellae); algae supply sugar and coral supply CO2 + detritus (nutrient containing organic matter)
with increase in peak summer ocean temperatures of just 1 degree C, corals can experience ābleachingā - algae have narrow temperature tolerance and are ejected by stressed coral
algae can also leave due to pollutants from runoff (sediment, pesticides, motor oil) and ocean acidification
coral also get destroyed by fishing practices such as bottom trawling
oil spills
hydrocarbons in crude oil (petroleum) are toxic to many marine organisms and can kill them, especially if they ingest the oil or absorb it through gills/skin
other physiological effectsā¦
decreased visibility and decreased photosynthesis due to less sunlight penetrating the water surface
oil sticking to bird feathers
oil sinking to bottom and killing bottom-dwellers due to direct toxicity or suffocation
oil can wash ashore and decreased tourism revenue and kill fish, decreasing the fishing industry revenue, and hurting restaurants that serve fish
cleanup can involve booms on surface to contain spread and ships with vacuum tubes to siphon oil off of the surface or devices to skim it off
physical removal of oil from beach sand and rocks with towels, soaps, and shovels
chemical dispersants sprayed on oil slicks to break up and sink to the bottom
clears up surface, but can smother bottom-dwellers
dispersant chemicals may be harmful
burning oil off surface
important eventsā¦
deepwater horizon oil spill (BP) - 2010
exxon-valdez oil spill
dead zones
result of excess fertilizer from agricultural runoff
algal blooms that die off, decompose, and then remove O2 from water, creating ādead zonesā
gulf of mexico has one of the largest dead zones in the us
8.3 Endocrine Disruptors & Industrial Water Pollutants
endocrine disruptors
chemicals that interfere with the endocrine system of animals by blocking hormone receptors
can lead to intersex, low sperm counts, cancer, or other reproductive/immune system effects
polychlorinated biphenyls (PCBs) and polybrominated biphenyls (PBBs)
sourcesā¦
atrazine (herbicide)
sourcesā¦
carried into groundwater from fields
can enter humans through unwashed produce
DDT (pesticide)
sourcesā¦
carried into groundwater from fields
phthalates (plastics and cosmetics)
sourcesā¦
enter surface and groundwater via intentional dumping of trash
chemical waste from plastic/cosmetic factories improperly disposing of waste
landfill leaching
also found in some cosmetics and plastic food containers (#3 plastic and āfragranceā)
heavy metals
mercury
sourcesā¦
coal combustion
trash incineration
cement production
inhibits estrogen and insulin
converted to methylmercury by bacteria in water sources (neurotoxicant)
accumulates and moves up the food chain
arsenic
sourcesā¦
naturally occurs and can dissolve in drinking water, formerly in pesticides
carcinogenic (causes cancer) as well as an endocrine disruptor
lead
sourcesā¦
old paint
old pipes
soils with PM from old vehicle exhaust
pharmaceuticals (flushed meds or leached from human waste)
sourcesā¦
enter sewage through human waste or flushed meds
8.4 Human Impacts on Wetland & Mangroves
wetlands
an area with soil submerged/saturated in water for at least part of the year, but shallow enough for emergent plants
ecosystem servicesā¦
provisioning
habitat for animals and plant foods
regulating
groundwater recharge, absorption of floodwater, CO2 sequestration
supporting
H2O filtration, pollinator habitats, nutrient cycling, pest control
cultural
tourism revenue, fishing license, camping fees, educational and medical research
mangrove swamps
estuary habitat along coast of tropical climates
mangrove trees with long, stilt roots stabilize shoreline and provide habitat for many species of fish and shellfish
provide ecosystem services (wood, fisheries, tourism, filtration, coastal protection, climate regulation)
large amount being destroyed by anthropogenic activity
8.5 Eutrophication
eutrophication process
extra input of N & P lead to eutrophication (excess nutrients) which fuels algae growth (limiting factors)
algae bloom covers surface of water, blocking sunlights and killing plants below surface
dead algae = decomposing bacteria, which use up dissolved O2 in the water
no dissolved O2 = drowning fish/other aquatic organisms
more dead organisms = more decomposing bacteria
positive feedback loop
major N/P sources
discharge from sewage treatment plants (N/P in human waste and phosphates in soaps/detergents)
animal waste from CAFOs
synthetic from agricultural fields and lawns
8.6 Thermal Pollution
thermal pollution - when heat released into water has negative effects on organisms living in the water
heat increases respiration rate of aquatic organisms (thermal shock)
as water temperature increases, dissolved oxygen and other nutrients decrease, meaning warmer water can support fewer living organisms
sources
power plants use cool water to cool down a wide variety of processes (machines, steam, etc.)
nuclear power plants use large amounts of water to power steam turbines and to remove surplus heat from the system
need to cool down reactor core as well as cooling the steam that was generated back into water
cooling towers/ponds
cooling towers/ponds are used to cool steam back into water and to hold warmed water before returning to local surface water
standard on nuclear power plants but water is not always cooled completely before being dumped back into surrounding waters
8.7 Persistent Organic Pollutants
POPs (persistent organic pollutants)
synthetic (human-made) compounds that do not easily break down in the environment; accumulate and buildup in water and soil (sediment)
fat-soluble, meaning they also accumulate and persist in animalsā fat tissue instead of passing through the body (donāt easily dissolve into blood/urine)
PCBs - polychlorinated biphenyls
group of industrial compounds that were once used to manufacture plastics and insulate electrical transformers
DDT - dichlorodiphenyltrichloroethane
outdated insecticide for killing mosquitoes that leads to thinning of bird eggshells
examples of POPs
DDT (outdated insecticide)
PCBs (plastic/paint additive)
PBDEs (fire-proofing)
BPA (plastic additive)
dioxins (fertilizer production and combustion of waste and biomass)
phthalates (plastics)
perchlorates (rocket/missile fuel, fireworks)
spread of POPs
spread throughout the global system
moved through organisms
travel in winds such as the prevailing westerlies
move through ocean currents like the gulf stream
8.8 Biomagnification
bioaccumulation - individual organism
absorption and concentration of compounds (especially fat-soluble ones like POPs) in the cells and fat tissues of organisms over time
biomagnification - multiple organisms
increasing concentrations of fat-soluble compounds like methylmercury and POPs in each level up the trophic pyramid or food web/chain
this is why pregnant women are advised not to eat sushi
8.9 Solid Waste Disposal
sources of solid waste
msw (municipal solid waste)
solid waste is what is in your garbage can; does not include air pollution or sewage
landfills are the most common destination of msw
waste āstreamā refers to flow of solid waste to recycling centers, landfills, or trash incineration (burning) facilities
e-waste
old tech - computers, tvs, phones, tablets
only ~2% of msw; considered hazardous waste due to metals like cadmium, lead, mercury, and PBDEs (fireproof chemicals)
sanitary landfills
APES lingo for ālandfillsā or where developed nations dispose of trash; different than ādumpsā which are just areas where trash is dumped, without the features below
clay/plastic bottom liner ā layer of clay/plastic on bottom of a hole in the ground; prevents pollutants from leaking out into soil/groundwater
leachate collection system ā system of tubes/pipes at bottom to collect leachate (water draining through waste and carrying pollutants) for treatment and disposal
methane recovery system ā system of tubes/pipes to collect that methane produced by anaerobic decomposition in the landfill
methane can be used to generate electricity or heat buildings
clay cap ā clay-soil mixture used to cover the landfill once itās full'; keeps out animals, keeps in smell, and allows vegetation to grow
8.10 Waste Reduction
reduce, reuse, recycle
reduce
reducing consumption is the most sustainable - use fewer resources, energy, packaging, etc.
ex) use a reusable water bottle instead of plastic ones
reuse
next most sustainable - not using energy to create a new products
ex) thrifting, turning old water into new furniture, using old containers as tupperware
recycle
least sustainable - processing and converting solid waste material into new products
requires energy to recycle materials
open-loop recycling - conversion of material into a new product
closed-loop recycling - a manufactured good is broken down to raw materials and recycled back into a similar product without significant degradation or waste
recycling pros and cons
pros
consume fewer raw materials
reduce use of energy in manufacture and processing
reduce need for disposal
decrease in pollution/emissions
cons
not cost effective
recycling sites often not cafe - contaminates/emissions
new products and degraded in quality and not durable
hard to implement on large scale or certain regions
many plastics are not recyclable
all-in one efficient
false sense of security!
e-waste
waste from electronics (phones, computers, etc.) that often contain heavy metals (lead, mercury, cadmium)
can leach these toxic metals into soil and groundwater if disposed of in landfills or open dump
can be recycled and reused to create new electronics, but often sent to developing nations for recycling due to health hazards, more strict environmental and worker protection laws in developing nations
can be dismantled and sold to countries that extract valuable metals (gold, silver, platinum) from motherboards
composting
creation of organic matter (humus)
decomposition under controlled conditions
produces an organic-rich material that enhances soil structure, CEC, and fertility
ensure a good carbon : nitrogen ration that will boost microbial activity
rotation and aeration to provide oxygen
if decomposition occurs anaerobically like in landfills, methane will be produced (bad GHG)
8.11 Sewage Treatment
water treatment process
primary treatment - physical removal of large debris (TP, leaves, plastic, sediment) with a screen or grate
secondary treatment - biological breakdown of organic matter (feces) by bacteria; aerobic process that requires O2
tertiary treatment - ecological or chemical treatments to reduce pollutants left after primary and secondary (N, P, bacteria)
disinfectant - UV light, ozone, or chlorine is used to kill bacteria or other pathogens, such as e coli
sewage treatment issues
combined sewage and stormwater runoff systems can cause wastewater treatment plants to flood during heavy rains, releasing raw sewage into surface waters
beneficial because it treats stormwater runoff normally, but causes overflow during heavy rains
raw sewage release contaminates surface waters withā¦
e coli
ammonia
nitrates
phosphates
endocrine disruptors (medications)
8.12 + 8.13 LD50 ; Dose Response Curve
dose response curve - illustrates the response of a population to a dose of a chemical/toxin - correlation between the toxin and its effects on the test population
threshold - the point where a response can be measured; if the response is death, then this is the point when the first subject dies
difference between toxicity and threshold
lethal dose 50% (LD50)
refers to the dose or concentration of the chemical that kills 50% of the population being studied
data usually expressed asā¦
mass (g, mg)/body mass unit mass (kg)
ppm - parts per million (in air)
mass/volume (in water of blood)
toxicity can be affected by age, genetic makeup, solubility, persistence and ability of one's detoxification system
only applies to the test population
lower the amount = more toxic the substance
effective dose 50% (ED50)
refers to the dose concentration of a toxin or chemical that causes a non-lethal effect (infertility, paralysis, cancer, etc.) in 50% of the population being tested
same general ās-shapeā as LD50 dose response curve, but at lower dose concentrations
8.14 Pollution & Human Health
routes of exposure and synergis
routes of exposure - ways that a pollutant enters the human body (food, breathing, water, etc.)
synergism - interaction of two or more substances to cause an effect greater than each of them individually (asthmatic gets covid)
dysentery
inflammation of intestines by bacteria and parasites
leads to severe diarrhea, bloody feces, and even death
caused by untreated water and sewage
kills 1.1M people annually, mostly in developing countries with poor sanitation and limited access to water infiltration
mesothelioma
caused by inhalation of asbestos
mesothelioma is a cancer that develop from constant damage to lung tissue
tropospheric ozone
worsens respiratory conditions like asthma, emphysema, bronchitis, and COPD
irritates muscles or respiratory tract, causing constriction of airways and shortness of breath
limits overall lung function
irritates eyes
8.15 Pathogens & Infectious Diseases
pathogen - a living organism (bacteria, fungus, protist, worm) or virus that causes an infectious disease