AP Environmental Science Course Review Part 4

Unit 8: Aquatic and Terrestrial Pollution

8.1 Sources of Pollutants

Point vs. nonpoint pollutant sources

• Point source: pollutant that enters environment from an easily identified and confined place

• Nonpoint source: pollutants entering the environment from many places at once

• Difficult to point to one individual source

Must-know Pollution Examples

Point sources

• Animal waste runoff from a CAFO (ammonia, fecal coliform bacteria)

• Emissions from smokestack of a coal power plant (CO@, NOx, SO2, PM)

• BP oil spill (hydrocarbons, benzene)

Nonpoint Source

• Urban runoff (motor oil, nitrate fertilizer, road salt, sediment

• Pesticides sprayed on agricultural fields, carried by winds and washed off large agricultural regions into bodies of water

• Estuaries and bays are polluted by many nonpoint sources from the large watershed that empty into them

Pollutants vs. Pollution

Pollutants: specific chemicals or groups of chemicals from specific sources with specific env. & human health effects

• Specific pollutant names, their sources, their env and human effects, their mitigation strategies on FRQs

Pollution: vague, nondescript term for any substance that is harmful to the environment (DONT USE ON FRQs)

• Exceptions: specific categories of pollution (thermal pollution, noise pollution, sediment pollution)

Biological Oxygen Demand (BOD)

• Amount of dissolved oxygen needed by aerobic bacteria to break down the organic matter in water

  • INCREASES with INCREASING organic matter

  • Lower BOD: indicates that a water body is less polluted, less oxygen is being used up by microorganisms

  • Higher BOD: water is more polluted and more oxygen is being used up by microorganisms

  • Inverse between DO and BOD

8.2 Human Impacts on Ecosystems

Range of Tolerance

• Organisms have range of tolerance for abiotic conditions in their habitat 

  • pH, temp, salinity, sunlight, nutrient levels (ammonia, phosphate)

• Also have range of tolerance for pollutants that human activities release into their habitats

• Pollutants cause physiological stress such as:

  • Limited growth; Limited reproductive function; Difficulty respiring/breathing and potentially asphyxiation (suffocation); hormonal disruption; death if high enough

Environmental Effects of Acid Rain

• pH tolerance: as pH decreases (more acidic) outside optimal range for species, pop. declines

  • When pH leaves range of tolerance they cannot survive at all due to aluminium toxicity, disrupted blood osmolarity (Na+/Cl- balance disrupted at low pH)

• Indicator species can be survey and used to determine conditions of an ecosystem

  • Ex. high whitemoss/filamentous algae pop indicated pH<6.0

  • High crustacean pop. indicated pH>6.0

Temp. Tolerance of Reef Algae

• Coral reef= mutualistic relationship between coral and photosynthetic algae called zooxanthellae

  • Algae supply sugar and coral supply CO2 + detritus (nutrient containing org. matter)

• Algae have narrow temp tolerance and leave the reef when temp rises

  • Pollutants from runoff (sediments pesticides, sunscreen) can also force algae from reef

• Coral lose color and become stressed and vulnerable to disease without algae (main food source)

Human Impacts on Coral Reef

• Humans disrupt coral reef ecosystems via greenhouse gas emissions (warming ocean temp. & bleaching coral)

• Overfishing decreases fish pop in coral reef ecosystem and bottom trawling can break reed structure and stir up sediment

• Urban and agricultural runoff also damages coral reef ecosystems

  • Sediment pollution: sediment carried into ocean by runoff makes coral reef waters more turbid-reducing sunlight/photosynthesis

  • Toxicants: chemicals in sunscreen, oil from roadways, pesticides from ag. Runoff

  • Nutrients (P/N): ammonia from animal waste, nitrates/phosphates from ag. or lawn fertilizers

Oil Spill Effects

• Hydrocarbons in crude oil (petroleum) are toxic to many marine org can kill them esp if they ingest the oil or absorb through gills/skin

• Other psychological effects: decreased visibility and decreased photosynthesis due to less sunlight and penetrated water surface; oil sticking to bird feathers; oil sinking to bottom and killing bottom-swellers due to direct toxicity and suffocation

• Oil can wash ashore and decrease tourism revenue and kill fish, decreasing fishing industry revenue, hurt restaurants that serve fish

  • Oil can settle deet in root structures of estuary hab like mangroves or salt marshes

  • Can be toxic to sat marsh grasses, killing them and loosening their root structure> coastline erosion

    • Can remove hab used by fish/shellfish for breeding grounds

Oil Spill Clean Up

• Oil spills occur when an underwater oil well explodes/blows out or when a tanker runs into a rock/iceberg and is punctures

  • 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, shovels

  • Chemical dispersants sprayed on oil slicks to break up and sink to the bottom

    • Cleans up surface, but can smother bottom-dwellers

    • Dispersant chemicals may be harmful

  • Burning oil off surface

8.3 Endocrine Disruptors and Industrial Water Pollutants

Endocrine Disruptors: chemicals that interfere with the endocrine (hormonal) systems of animals

• Bind to cellular receptors mant for hormones, blocking the hormone from being received or amplifying its effects

  • Human medications that pass through urine and sewage or are flushed down toilet are a common source (meant to influence human hormones, so they can disrupt animals’)

• Atrazine (herbicide) binds to receptors of cells that convert estrogen to testosterone in male frogs>leads to high estrogen in males, low sperm count, even feminization (development of eggs in the testes or ovary formation)

• Atrazine: broad-spectrum herbicide used to control weeds and prevent crop loss

  • Applied to ag. fields, runs off into local surface or groundwater or is carried by wind

  • Can contaminated human well-water, or enter body via unwashed produce

• DDT: broad-spectrum insecticide that was phased out, but still persists in env.

  • Applied to ag. fields, runs off into local surface or groundwater or is carried by wind

• Phthalates: compounds used in plastic and cosmetic manufacturing

  • Enter surface and groundwater via intentional dumping of trash, or chemical waste from plastic/cosmetic factories improperly disposing of waste, landfill leaching

  • Also found in some cosmetics and plastic food containers 

• Lead, arsenic, mercury: heavy metals

• Many human medications that enter sewage via human urine or flushed meds

Mercury

• Mercury: naturally occurring in coal, released by anthropogenic activities

  • Coal combustion, trash incineration, burning medical waste, heating limestone for cement

    • Attacked to PM released by burning and deposits in soil/water wherever PM settles

    • Can be released if coal ash stores in ponds overflow/runoff

  • Endocrine disruptor: inhibits estrogen and insulation (menstrual cycle and ovulation)

  • Teratogen: chemical harmful to developing fetuses; can accumulate in fetus brain

    • Pregnant women can reduce risk by eating less seafood

• Mercury itself isn't toxic, but bacteria in water converts it to methylmercury which is toxic to animals (neurotoxicant that damages central nervous system)

Arsenic & Lead

• Arsenic: naturally occurring element in rocks underground that can dissolve into drinking water

• Natural release into groundwater can be worsened by mining

  • Anthropogenic sources: formerly in pesticides applied to ag. fields (can linger in soil, wood treatment chemicals to prevent rot, coal combustion and ash)

    • Carcinogenic (lungs, bladder, kidneys)

    • Endocrine disruptor (glucocorticoid system)> can be removed with water filters

• Lead: found in old paint (in homes), old water pipes, and soils contaminated by PM from vehicles exhaust before it was phased out of gas in 70s

  • Also released in fly ash (PM) of coal combustion

    • Neurtotoxicant (damages central nervous system, esp in children)

    • Endocrine disruptor and can be removed with water filters

Coal Ash

• Can be source of mercury, lead, and arsenic

• Can attach to fly ash (PM) from smokestack and be carried by wind, deposited in ecosystems far away

• Both fly and bottom coal ash are usually stored on site in ponds, dug into soil, lined with plastics

  • Ponds can leach into groundwater, contaminating it w arsenic, lead, mercury

  • Ponds can overflow & runoff into nearby surface water and agricultural fields

4.6 Watersheds

• Watershed: all of the land that drains into a specific body of water

• Determined by slope, ridges of land divide watersheds

• Vegetation, soil composition, slope play a role in how watersheds drain

  • More vegetation= more infiltration and groundwater recharge

  • Greater slope= faster velocity of runoff & more soil erosion

  • Soil permeability determines runoff vs. infiltration rate

• Human activities of watershed impact H2O quality: ag. Clearcutting, urbanization, dams, mining

Chesapeake Bay Watershed

• 6 state region that drains into a series of streams/rivers and then chesapeake bay

• Mix of fresh & salt water + nutrients in sediment make estuary habitats like the salt marshes highly productive

• Estuaries + wetlands provide ecosystem services:

  • Tourism revenue: hotels, restaurants, permits

  • Water filtration (grass roots trap pollutants)

  • Habitats for food sources (fish/crabs)

  • Storm protection (absorbing and buffering floods)

Human Impacts on Chesapeake Bay

• Nutrient pollution (N/P) >> eutrophication in the Bay

  • Algae bloom due to increase of N/P>decreased sunlight>plants below surface die>bacteria uses O2 for decomposition>hypoxia (low O2) and dead zones

• Major N/P sources:

  • Discharge from sewage treatment plants (from human waste)

  • Animal waste from CAFOS

  • Synthetic fertilizer from ag. Fields and lawns

• Other major pollutants:

  • Endocrine disruptors from sewage treatment

  • Sediment pollution from deforestation, urbanization, tilling ag. fields 

    • Increases turbidity (reduced photosynthesis) and covers over rocky streambed habitats

Direct Effects of Clearcutting

• Soil erosion: caused by loss of stabilizing root structure

  • Removes soil organic matter and nutrients from forest

  • Deposits sediments in local streams

    • Warms water + makes more turbid/cloudy

• Increased soil + stream temp.: loss of shade increases soil temp

  • Soil has lower albedo than leaves of trees

• Loss of tree shade along rivers + streams warms them

  • Erosion of sediment into rivers also warm them

Solutions to Watershed Pollutants

• Cover crops: certain type of grass to anchor soil in between harvests (prevents sediment runoff and filters fertilizer used)

• Riparian buffers: plants/producers lining to absorb runoff (more percolation/infiltration)

• Animal manure management: improve CAFOS holding facilities (lining to hold more, to prevent leaking)

• Septic tank upgrades: countryside; easy to contaminate water supplies

• Enhanced nutrient removal: takes high amounts for nitrogen phosphorus to be dangerous; needs to be priority to remove excess nutrients before it becomes a water medium

8.4 Human Impacts on Wetlands and Mangroves

Wetlands

• Wetlands: Area with soil submerged/saturated in water for at least part of the year, but shallow enough for emergent plants

  • Wetland plants have adapted to living with roots submerged in standing water (cattails, lily pads, reeds)

• Ecosystem services:

  • Provisioning: habitat for animal and plant foods

  • Regulating: groundwater recharge, absorb of floodwater, CO2 sequestration

  • Supporting: H2O filtration, pollinator habitats, nutrient cycling, pest control

  • Cultural: tourism revenue, fishing license, camping feeds, ed/med research

Threats to Wetland

• Pollutants: nutrients (N/P), sediment, motor oil, pesticides, endocrine disruptors

• Development: wetlands can be filled in or drained to be developed into homes, parking lots, stores, or agricultural land

  • Water division upstream for flood control, agriculture, or drinking water can reduce water flow and dry up wetlands

  • Dam construction for flood control/hydroelect. reduces water and sediment flow to wetlands

• Overfishing: disrupts food web of wetlands (decrease in fish predators, increase in prey)

Benefits of and threats to mangroves

• Wood: density of mood makes valued source of timber/fuel

• Coastal protection: 

• Livelihoods: 120 mil people live near mangroves

• Mangrove ecosystem services: worth $33,000-57,000 per hectare per year x 14 million hectares = $800 billion a year

• Climate regulation: carbon storage potential of mangroves is 3-5x higher than tropical upland forest due to strong carbon storage in soil. CO2 released by global mangrove loss annually coils be as high as annual 

• THREATS: mangrove loss, climate change, coastal development, aquaculture, agriculture, logging, pollution

8.5 Eutrophication

Eutrophication Process

• Extra input of N/P (limiting nutrients)>eutrophication (excess nutrients) which fuels algae growth

  • Algae bloom covers surface of water, blocking sunlight and killing plants below surface

  • Algae eventually die off>bacteria that break down dead algae use up O2 in the water because decomposition is an aerobic process

  • Lower O2 levels in water kills aquatic animals (fish)

  • Bacteria use up more O2 to decompose dead aq. animals

• Creates pos. Feedback loop: less O2>more dead org.> more bacterial decomp > less O2

Cultural Eutrophication

• Anthropogenic nutrient pollution that leads to eutrophication

  • Algae bloom due to increase of N/P> decreased sunlight>plants below surface die>bacteria use up O2 for decomp>hypoxia (low O2) and dead zones

• Major N/P sources:

  • Discharge from sewage treatment plants (N/P in human waste and phosphates in soaps/detergents)

  • Animal waste from CAFOS

  • Synthetic fertilizer from ag. fields and lawns

Oligotrophic Waterways

• Oligotrophic waterways: Waterways with low nutrient (N/P) levels, stable algae population, and high dissolved oxygen (clearer water)

• Can be due to lack of nutrient pollution or age of the body of water

• Aquatic ecosystems naturally undergo succession

  • Sediment buildup on bottom (benthic zone) which leads to higher nutrient levels

  • Overtime, ponds naturally shift from oligotrophic> mesotrophic> eutrophic

Dissolved Oxygen & Dead Zones

• Decrease in dissolved oxygen (hypoxia)> dead zone

  • All aq. life requires DO (dissolved oxygen) in water for respiration

  • As DO decreases, fewer species can be supported

    • Most fish require at least 3.0 ppm to survive, 6.0 ppm to reproduce

8.6 Thermal Pollution

Solubility of Oxygen & Temperature

• Solubility: ability of a solid/liquid/gas to dissolve into a liquid (oxygen dissolving into water in this case)

• Inverse relationship between water temp and oxygen solubility 

  • AS WATER TEMP INCREASES, DISSOLVED OXYGEN (DO) DECREASES

• Thermal pollution: when heat released into water has negative effect on organisms living in the water

  • Heat increases respiration rate of aquatic organisms (thermal shock)

  • Hot water also has less O2

    • Leads to suffocation without enough O2 to support respiration

Sources of Thermal Pollution

• Power plants use cool water from surface/ground water sources nearby to cool steam used to turn a turbine back into water to reuse

  • Steel mills, paper mills, other manufacturing plants also use cool water to cool down machinery and return warmed water to local surface waters

  • Urban stormwater runoff can also cause thermal pollution due to heat from blacktop/asphalt

• Nuclear power plants require esp large amounts of cool water to cool steam back into water and to cool the reactor core

Cooling Towers

• Cooling tower/ponds: used to cool steam back into water and to hold warmed water before returning to local surface water

  • Can be optimized to cool water better/hold it longer before returning to nearby surface waters

8.7 POPS (Persistent Organic Pollutants)

POPS

• Persistent (long lasting) Organic (carbon-based) Pollutants

  • Synthetic (human-made) compounds that do not easily breakdown in the environment; accumulate and buildup in water and soil

• Fat-soluble; also accumulate and persist in animals’ fat tissue instead of passing through the body 

  • Does not easily dissolve into blood/urine)

  • Can be slowly released from fatty tissue into the bloodstream and impact brain & other organs over time (esp. Reproductive system)

Examples & Sources of POPs

• Examples: DDT (outdated insecticide); PCBs (plastic/paint additive); PBDEs (fire-proofing); BPA (plastic additive); dioxins (fertilizer production and combustion of waste & biomass); phthalates (plastics); percholcated (rocket/missile fuel, fireworks)

• Pesticides: DDT was widely used as an insecticide before phaseout in many developed countries

  • Still in soils and sediments in aq. ecosystems and builds up in food webs

• Medications (pharmaceutical compounds): steroids, reproductive hormones, antibiotics that pass through human bodies & into sewage release from treatment plants

  • Persist in streams/rivers & disrupt aq. organisms’ endocrine function

• Dioxins: byproduct of fertilizer production + burning of medical waste, FFs, biomass

  • 90% of human dioxin exposure comes from animal fats (meat, dairy, fish) since dioxins buildup in animal fat tissue

Examples & Transport of POPS

• PCBs: additive in paint and plastics, released into aquatic ecosystems by industrial wastewater

  • Toxic to fish> causes spawning failure & endocrine disruption

  • Reproduce failure and cancer in humans (human expore through animal products)

• Perchlorates: given off by rockets, missiles, and fireworks

  • Especially common near military testing sites or rocket launch pads

  • Remain in soil; can leach into groundwater or runoff into surface waters

• POPs travel through wind + water

  • Wastewater release form industrial processes leachate from landfills or improperly buried industrial waste, fertilizer/pesticide production, emissions from burning waste/biomass

8.8 Biomagnification

Bioaccumulation: absorption and concentration of compounds (esp fat-soluble ones like POPS) in cells and fat tissues of organisms

• Fat-soluble compounds like POPs and methyl mercury don't dissolve easily in water, they don't enter blood easily and dont leave body in urine easily

  • Instead the build up in fat tissue

  • Leads to them building up to reach higher concentrations in the organism over time

Biomagnification: increasing concentrations of fat-soluble compounds like methylmercury and POPs in each level up the trophic pyramid or food web/chain

• Biomagnification begins with POPs or methylmercury in sediments or plants in an ecosystem (phytoplankton, grass)

  • Primary consumers (zooplankton, feeding fish, insects) take in POPs by eating producers, causing bioaccumulation of POPs in their tissues

  • Secondary consumers east primary consumers and take in the POPs in their tissues

    • Because of 10% rule, organisms at each trophic level need to eat more and more biomass to receive enough energy>leads to higher POP levels over their lifetimes

    • Large predators like salmon, dolphins, whales have higher POP/methylmercury levels

Biomagnification (DDT)

• DDT banned in many developed countries but still in sediments of many bodies of water

  • Taken in by bottom feeders/zooplankton and biomagnified at higher trophic levels

  • Reach highest levels in top predators esp predatory birds like eagles and osprey

    • Causes thinning of eggshells in the birds

    • Massive pop decline of bald eagle in US which prompted Endangered Species Act (1973)

Biomagnification (methylmercury)

• Mercury is emitted from burning coal and by volcanoes, and carried by wind and deposited in water where bacteria convert it to toxic methylmercury

  • Taken in by phytoplankton and biomagnified at higher trophic levels

  • Reach highest levels in top predators (tunas, sharks, whales)

    • Neurotoxicant damages the central nervous system of animals

  • Human exposure to methyl/mercury and POPS come from eating large predatory fish like tuna/salmon/etc

    • Damage to human nervous system (esp developing fetus) and disrupt reproductive system

8.9 Solid Waste Disposal

Waste: material outputs from a system that are not useful or consumed

Waste Type and Sources

• MSW (municipal solid waste): solid waste from cities (households, businesses, schools, etc.)

  • Waste stream refers to flow of solid waste to recycling centers, landfills, or trash incineration (burning) facilities

    • Aka trash, litter, garbage, refuse

• E-Waste: old computers, TVs, phones, tablets

  • Only 2% of MSW, considered hazardous due ti metals like cadmium, lead, mercury, and PBDEs (fireproof chemicals)

• Can leach endocrine disrupting chemicals out of landfills if thrown wih regular MSW (should be disposed at special facilities that recycle parts)

Sanitary Landfills

• Lingo for landfills or where developed nations dispose of trash, different than dumps that are areas where trash is dumped without features:

  • clay/plastic bottom liner: layer of clay/plastic on the bottom of a hole in the ground to “prevent” pollutants from leaking out into soil/groundwater

  • Storm water collection system

  • Leachate collection system: system of tubes/pipes at bottom to collect leachate (water draining through waste and carrying pollutants) for treatment + disposal

  • Methane recovery system: system of tubes/pipes to collect the methane produced by anaerobic decomposition in the landfill

    • Methane can be used to generate electricity or heat buildings

  • Clay cap: clay-soil mixture used to cover the landfill once its full; keeps animals out, keeps in smell, and allows vegetation to grow

Landfills Contents & Decomposition

• Landfills generally have a very low rate of decomp due to low O2 moisture + organic material combination

  • Little decomp occurs and landfills typically remain about same size as when filled

• Things that should NOT be landfilled:

  • Hazardous waste (antifreeze, motor oil, cleaners, electronics, car batteries)

  • Metals like copper and aluminum should be recycled

  • Old tires (left in large piles that hold stagnant water which is good 4 mosquito breeding)

• Things that SHOULD be landfilled:

  • cardboard/food wrappers that have too much food residue and cant be recycled

  • Rubber + plastic films/wraps

  • Styrofoam

  • Food, yard waste, and paper can and do go in landfills but should be recycled/composted

Landfill Issues

• Landfills> groundwater contamination + release of GHGs

  • Groundwater can be contaminated with heavy metals (lead, mercury), acids, medication, and bacteria if leachate leaks through lining into soil/groundwater beneath

  • Greenhouse gases (CO2/CH4 methane) are released from landfills due to decomposition contributing to global warming + climate change

• NIMBY (not in my back year)= idea that communities don't want landfills near them for a number of reasons

  • Smell + sight

  • Landfills can attract animals (crows, rats)

  • Groundwater contamination concerns 

    • Landfills should be located ar from river and teams and neighborhoods to avoid water contamination

• Landfills are usually placed near low-income or minority communities that don't have the resources/political power to fight against

Waste Incineration & Ocean Dumping

• Waste can be incinerated/burned to reduce the volume that needs to be landfilled since most waste (paper,plastic, food)= hydrogen, carbon, and oxygen that combusts at high temp.

  • Can reduce volume by 90% but releases CO2 + air pollutants (PM, SOx, NOx)

    • Bottom ash may contain toxic metals (lead, mercury, cadmium) and is stored in ash ponds then taken to special landfills

    • Toxic metals can leach out of storage ponds or be released into atmosphere

• Can be burned to generate electricity

• Illegal ocean dumping occurs in some countries with few environmental regulations or lack of enforcement

  • Plastic esp collects into large floating garbage patches in the ocean

  • Can suffocate animals if they ingest it or entangle them so they cant fly or swim and may starve

8.10 Waste Reduction

Reduce, Reuse, Recycle

• Reducing consumption is the most sustainable because it decreases natural resources harvesting and the energy inputs to creating packaging and shipping goods

  • Ex. metal/reusable water bottle to reduce plastic use OR riding bikes/walking to reduce gasoline use

    • Reusing= the next most sustainable b/c it doesnt require additional energy to create a product 

  • Ex. burning second hand clothes, using old wood pallets for furniture, washing plastic takeout containers and reusing

• Recycling = processing and converting solid waste material into new products

  • Ex. glass being turned into glass again (closed loop), plastic water bottles being turned into fabric for clothes/jackets (open loop)

    • Least sustainable of the three Rs due to the amount of energy it requires to process and convert waste materials

Recycling Pros and Cons

• Pros: reduces demand for new materials, esp metals and wood that causes habitat distinction and soil erosion when harvested

  • Reduces energy required to ship raw material and produce new products (fewer FF, less CC)

  • Reduces landfill volume, conserving landfill space and reducing need for more landfills

• Cons: recycling is costly and still requires significant energy

  • Cities that offer recycling services need to process, sort and sell collected materials; prices change rapidly, leading to recycled materials often being thrown away

    • When citizens recycle items that shouldn't be recycled (wrappers with food, styrofoam, etc) that increases cost for cities to sort and process

Composting

• Organic matter being decomposed under controlled conditions

  • Red gi uces landfill volume and produces rich organic matter that can enhance water holding capacity, nutrient levels of agricultural or garden soil (produces valuable product to sell>compost)

  • Reduces the amount of methane released by anaerobic decomposition of organic matter in landfills

  • Should be done w proper mix of “browns” (carbon) to “greens” (N)> 30:1

    • Should be aerated + mixed to optimize decomposition, bacteria need O2 for decomp

  • Potential drawbacks: foul smell that can be produced if not properly rotated and aerated and rodents/other pests may be attracted

E-Waste

• Waste from electronics that often contain heavy metals (lead, merc, cadmium)

  • Can leach these toxic metals into soil/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 env. And worker protection laws in developing nations

  • Can be dismantled and sold to countries that extract valuable metals (gold, silver, platinum) from motherboards

  • Often burned or dumped due to less strict env. Regulations or lack of enforcement in developing nations

Waste to Energy

• Waste can be incinerated (burned) to reduce the volume and also generate electricity; most waste (paper, plastic, food)= hydrogen, carbon, and oxygen so it easily combusts at high temp

  • Same process as burning coal. NG, biomass

  • heat>water>steam>turbine>generator>electricity

• Methane gas produced by decomposition in landfill can be collected with pipes and burned to generate electricity

  • heat>water>steam>turbine>generator>electricity

  • Reduces landfill volume

  • Produced electricity with fracking or mining for FFs

8.11 Sewage Treatment

Water Treatment Process

• Primary treatment: physical removal of large debri (Toilet paper, leaves, plastic, sediment) with a screen or grate

• Secondary treatment: biological breakdown of organic matter (feces) by bacteria; aerobic process that requires O2

  • Aeration speed it up

• Tertiary treatment: chemical treatment to reduce pollutant levels (nitrate, phosphate ammonia)

• Disinfectant: UV light, ozone, or chlorine is used to kill bacteria or other pathogens such as e. Coli

• Effluent: liquid waste (sewage) discharged into a surface body of water, typically from a wastewater treatment plant

Primary and Secondary Treatment

Primary: screens or grates filter out large solids + grit chamber allows sediment to settle out and be removed

Secondary: O2 is bubbled into an aeration tank filled with bacteria that break down org. matter into CO2 and nutrients like N & P

• Removed 70% of P and 50% of N and does not remove POPs such as medications or pesticides

Sludge: inorganic, solid waste that collects at the bottom of tanks in primary and secondary treatment

• Water is spun/pumped off to concentrate it further

• Dry, remaining physical waste is collected to be put in landfill, burned, or turned into fertilizer pellets 

After primary & secondary treatment, some plants go directly to disinfectant (UV, ozone, chlorine) & discharge into surface water, while some will use tertiary treatment to remove more nutrients before discharge

Tertiary Treatment

• Uses chemical filters to remove more of the nitrates & phosphates from secondary treatment discharge

• Critical step because effluent that is discharged into surface waters with elevated nitrate/phosphate levels leads to eutrophication

• Expensive and not always used

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 b/c it treats stormwater runoff normally, but causes overflow during heavy rains

• Raw sewage release contaminates surface waters with:

  • E. coli

  • Ammonia

  • Nitrates

  • Phosphates

  • Endocrine disruptors (medications

• Even treated wastewater effluent released into surface water often has elevated N/P levels and endocrine disruptors (medications passed through the body)

8.12/8.13 LD50 and Dose Response Curve

Dose Response Studies & LD 50

• As climates change and warm-climate biomes spread further north and south, many tropical diseases are also expanding their range into areas they did not previously affect

  • Pathogens spread rapidly when areas are experiencing poverty, lack of sanitation, and do not have clean drinking supplies

•  Studies that expose an organism to different docs of concentrations of a chemical in order to measure the response (effect) of the organism

• Independent variable: concentration of the chemical, added to food, water, or air

• Dependent variable: response measured in org (usually death or impairment)

  • LD50 refers to the dose or concentration of the chemical that kills 50% of the population being studied (MASS OF CHEMICAL TO BODY MASS OF ORGANISM)

  • LD50 data are usually expressed as:

    • Mass (g,mg)/body unit mass (kg)

    • Ppm - parts per million (in air)

    • mass/volume (in water of blood)

Dose Response Curve

• The data from the dose response study, graphed with percent mortality or other effect on the y axis and dose concentration of chemical on x axis

  • Lowest dose where an effect (death, paralysis, cancer) starts to occur is called the threshold of toxicity threshold

  • Dose response curves are usually S-shaped, low mortality of low dose, rapid increase in mortality as dose increases, leveled off near 105 mortality of high dosage

ED50 and other Dose Responses

• 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 pop tested

Dose Response Data and Human Health

•  Dose-response studies for toxic chemicals are not done on humans; data from other mammals (mice, rats) are used to simulate human toxicity

• To determine maximum allowable levels for humans, we generally divide LD50 or ED50 dose concentration by 1,000 for extreme caution

• Acute vs. Chronic studies: Most dose-response studies are considered acute, since they usually only measure effects over a short period of time; they’re also isolated to a lab, so they don’t measure ecological effects of organisms dying (trophic cascades) 

  • Chronic studies are longer-term and follow developmental impacts

  • Ex: study of fish from hatchlings to adults to study sexual maturation

8.14 Pollution and Human Health

Routes of Exposure and Synergism

• Routes of Exposure

  • lead>water pipes and paint chips

  • mercury> seafood (tuna)

  • CO> indoor biomass comb.

  • PM> pollen, dust, etc

  • Arsenic> rice, groundwater

• Synergism: the interaction of 2+ substances to cause an effect greater than each of them individually

  • Asthma caused by PM from coal PPs and COVID-19 damaging lungs

  • Carcinogenic effect of asbestos combined with lung damage from smoking

• Makes it hard to pinpoint the extract effects of one specific pollutant on humans

Synsentery

• Dysentery: Bacterial infection caused by food or water being contaminated with feces (often from sewage release into rivers + streams used for drinking water)

• Causes intestinal swelling and can result in blood in feces

  • Results in severe dehydration due to diarrhea (fluid loss)

  • Kills 1.1 mil people annually, mostly in developing countries with poor sanitation and limited access to water filtration

• Can be treated with antibiotics that kill the bacteria causing the infection and access to treated, filtered water that can rehydrate

Mesothelioma (asbestos)

• A type of cancerous tumor caused by exposure to asbestos, primary affecting the lining (epithelium) of the rep tratc, heart, or abdominal cavity

  • Asbestos exposure comes primarily from old insulation materials used in attics, ceiling and flooring boards; when the insulation becomes physically disturbed, asbestos particles are released into the air & inhaled

  • Removal of asbestos-containing insulation material should be done by professionals with proper training and equipment that protects them from inhaling the asbestos

    • The area where asbestos is removed from should be sealed off from other areas in the building and well-ventilated during the removal process

    • Insulation without asbestos should be used to replace it

Tropospheric Ozone

• Worsens respiratory conditions like asthma, emphysema, bronchitis, COPD

  • Limits overall lung function: irritates muscles or resp tract causing constriction of airways and shortness of breath; irritates eyes

  • Sources: photochemical breakdown of NO2 (car exhaust, coal, and NG combustion)

• Only harmful in troposphere (beneficial in stratosphere)

8.15 Pathogens and Infectious Diseases

• Pathogens: A living organism (virus, bacteria, fungus, protist, worm) that causes an infectious disease

• Infectious diseases are capable of being spread or transmitted (HIV, ebola, Covid-19); noninfectious diseases are not transmissible (heart disease, asthma, cancer, diabetes)

• Pathogens adapt and evolve to take advantage of humans as hosts for their reproduction and spread (Covid-19 is a SARS-associated coronavirus that evolved to become especially effective at surviving and reproducing in humans)

• Vectors: A living organism (rat, mosquito) that carry and transmit infectious pathogens to other organisms

• Climate change is shifting equatorial climate zones north and south away from the equator; this brings warmer temperatures to subtropical and temperate regions

• Warmer temperatures allow pathogens and their vectors (mosquitos) to spread north & south to parts of the world previously too cold

  • Many pathogenic bacteria and viruses survive and replicate better in warmer weather

Plague

• Bacterial (pathogen) infection transmitted by fleas (vector) that attach to mice and rats (vectors)

  • Transmitted by flea bite, rodent contact, or contaminated human fluid

  • Aka bubonic or black plague; modern antibiotics are highly effective against it but some isolated instances still occur

Tuberculosis

• Bacterial (pathogen) infection that targets the lungs

  • Transmitted by breathing bacteria from body fluids (resp. droplets) of an infected person, which can linger in air for hours

  • Causes night sweats, fever, coughing blood; treatable in developed nations with aceess to powerful antibiotics

  • Leading cause of death by disease in the developing world - 9 million cases per year and 2 million deaths 

Malaria

• Parasitic protist (pathogen) caused by bite from infected mosquitos (vector)

  • Most common in sub-saharan africa (and other tropical regions of middle east, asia, south and central america; recurring flu-like symptoms; kills most children under 5

  • Can be combated with insecticide spraying that kills mosquitoes; US eradicated in 1951

West Nile

• Virus (pathogen) infection caused by infected mosquitoes (vector) 

  • Birds are the main host, but the virus can be transmitted to humans by mosquitos  that bite infected birds and then bite humans

  • Causes brain inflammation, which can be fatal

Zika Virus

• Virus (pathogen) infection caused by bite from infected mosquitos (vector) and sexual contact

  • Causes babies to be born w abnormally small heads and damaged brains; can be passed from mother to infant

  • No known treatment currently, so prevention is focused on eliminating mosquito pop

SARS (severe acute respiratory syndrome)

• Coronavirus (pathogen) infection caused by respiratory droplets from infected person

  • Primarily transmitted by touching or inhaling fluids from an infected person

  • Causes a form of pneumonia

  • Initial outbreak was in southeast asia

  • SARS-CoV-2 is the virus that causes COVIS-19

MERS (middle east respiratory syndrome)

• Virus (pathogen) respiratory infection that is transmitted from animals to humans

  • Originated on arabian peninsula

Cholera

• Bacterial (pathogen) infection caused by drinking infected water

  • Vomiting, muscle cramps, diarrhea, can cause severe dehydration

  • Can be introduced by water contamination with human feces or undercooked seafood

Infectious Disease and Development

• Less developed, poorer countries typically have higher rates of infectious disease

  • Less sanitary waste disposal, pathogens can reproduce in open water areas where children may play or animals may scavenge and pass to humans

  • Less access to healthcare facilities

Laws to Know

• CWA (Clean Water Act): law regulating discharged of pollutants in bodies of water

• SDWA (safe drinking water act): protects underground sources of drinking water from contamination by underground injection of fluids

• RCRA (resource conservation and recovery act): “cradle-to-the-grave” law that manages the framework of hazardous and nonhazardous waste

• CERCLA(comprehensive environmental response, compensation, and liability act)/Superfund: law monitoring toxic waste sites that require monitoring and clean up

• Delaney Clause of Food, Drug, and Cosmetic Act: clause that requires FDA to ban food additives that cause or induce cancer in humans/animals

1. Around 190 million gallons

2. decreased photosynthesis due to less sunlight and penetrated water surface; oil sinking to bottom and killing bottom-swellers due to direct toxicity and suffocation; food webs can be disrupted

3. Decreased revenue from decreased money earned from tourism; clean up cost may be high; fishing industry may decrease; increased jobs

4. ,

   1. One advantage to the use of chemical dispersants for oil spill cleanup: breaks doen oil to small droplets, reducing toxicity; applies quickly; slows spread; protects birds. Disadvantages: does not actually get rid of oil, may damage underwater ecosystems and may be toxic, oil can be dispersed but not removed

   2. One biological method used for oil spill cleanup: microbes that degrade/consume oil;physical: burning oil, vacuuming/degrading, physical washing, absorbing, booms and skimming

5. One other source of oil contamination can be:

6. One substitute for petroleum in a specific consumer product (other than fuel): paper bags, corn/plant-based plastic water bottles

Unit 9: Global Change (Monday, May 24th)

9.1 Stratospheric Ozone Depletion

Difference between “good” ozone and “bad” ozone?

• Good ozone in stratosphere that protects/absorbs from UV radiation 

• Bad ozone: Ground-level; photochemical oxidant (sunlight reacts with SO2 and NOs) in the troposphere

How does the Ozone layer form?

• Step 1: Oxygen molecule (O2)+ UV rays(UV-C) = atomic oxygen( 2 O) (2 single oxygen atoms)

• Step 2: atomic oxygen(O) + oxygen molecule (O2) = ozone (O3)

What are CFCs?

• Ozone is being depleted by CFCs (chlorofluorocarbons)

  • Organic, MAN-MADE, synthetic, nontoxic, nonflammable, very stable

    • Contain C, Cl, F

  • Primary pollutant: put directly into the atmosphere

  • Source of pollution: refrigerators, air conditioners, fire suppressants, aerosol sprays

• CFC can last in the atmosphere for up to 45 years

• Ozone layer in stratosphere is protector (absorbs UV rays)

• Sunlights breaks a Cl- atom from the CFC atom; chlorine atom encounters an ozone molecule; chlorine removes an oxygen atom from ozone (O3)=O2 & O+Cl; Free oxygen atom releases chlorine

• POSITIVE FEEDBACK LOOP

What is the hole in the ozone layer

• In the mid 80s it was noticed that there was thinning of the layer in Antarctica

• Happened b/c there are a lot more free ice molecules in the atmosphere that encourages chlorine process to occur

Increased UV on human health

• Cataracts: intense UV light on the eyes, causes cloudiness

• Skin cancer: melanocytes produce melanin to protect the skin from UV rays; if UV rays exceed what can be blocked by your level of melanin, sunburn results

9.2 Reducing Ozone Depletion

What important international agreement limited/banned CFCs in many countries?

• Replacing CFCs with HFCs (hydrofluorocarbons); still a greenhouse gas but doesn't do same damage

• Montreal protocol of 1987: lot of nations came together and agreed to ban/reduce CFCs emitted into the atmosphere (EFFECTIVE!)

9.3 The Greenhouse Effect

• Greenhouse gases let the sun’s short wave radiation (visible light) reach the earth, but trap some of the long wave (infrared or heat) radiation coming from the warm earth

  • 1. Incoming solar radiation = UV and visible light

  • 2. 1/3 reflected back into space

  • 3. Remaining lights is absorbed by clouds and planets surface (these become warmer and emit infrared radiation)

  • 4. Radiation is either absorbed by the GHGs or emitted into space

  • 5. More greenhouse gases= more IR absorbed and emitted back to earth

• The process should be in equilibrium (short term, inputs might be higher or lower, which causes global warming/cooling; ice ages)

Greenhouse gases in the atmosphere

• N2 and 2 = 99% of greenhouse gases - NOT GHGs

• Greenhouse gases responsible for trapping heat in the atmosphere

  • Major greenhouse gases: 

    • Water vapor (H2O): short residence time so does not contribute much; absorbs more IR than anything but does not persist)

    • Carbon Dioxide (CO2): used as a reference point for climate change

    • Methane (CH4): very strong GHG; 

    • Ozone (O3)

    • Nitrous Oxide (N2O)

    • CFCS (not natural)

• Global warming potential: how much a molecule can contribute to global warming over 100 years relative to a molecule of CO2 (how well it absorbs IR, how long it persists)

  • Potential + concentration = total effect

• Natural sources of GHGs: 

  • Volcanoes- ash reflects incoming radiation, so cooling effect

  • decomposition/digestion- dead organic matter converted into CO2 unless there is not enough O2 (not enough O2> its converted to CH4)

  • Methane from wetlands; termites

  • Denitrification- N2O (nitrous oxide) (nitrate NO3> nitrite NO2> nitric oxide NO> nitrous oxide N2O> nitrogen gas N2)

  • Evaporation and evapotranspiration- water vapor

9.4 Increases in Greenhouse Gases

Anthropogenic sources of GHGs

1. Fossil fuels- CO2, methane, N2O (PM lowers albedo that does not reflect sunlight/absorbs heat, black soot)

2. Agriculture- overirrigation= low O2, so methane; fertilizers= denitrification; livestock= cattle and sheep methane

3. Deforestation- less photosynthesis, more CO2, burning releases PM, methane, N2O

4. Landfills- methane (food scraps/garden waste create acids in anaerobic conditions and pollute groundwater; leachate soaks into surrounding ground and contaminated groundwater; methane produced from food waste kept in anaerobic conditions)

5. Modern chemicals like CFCs (HCFCs do not create as big of problem)

Human sources of methane

1. Fossil fuel production, distribution

2. Livestock farming

3. Landfills and waste all 3 = 80%

4. Biomass burning

5. Rice agriculture

6. Biofuels

Nitrous Oxide

1. fertilizers/agricultural soil

2. Fossil fuels are majority

Carbon dioxide

1. Fossil fuel combustion = 95%

   1. Transportation 42%

   2. Industrial 23%

   3. Electricity generation(in state) 14%

   4. Electricity generation (imports) 10%

   5. Residential 6%

9.5 Global Climate Change

• Global Change: Planetary-scale changes in Earth Systems (land, air, life, soil, atmosphere, oceans, humans)

• Global Climate Change: Changes in temp., precipitation, wind, storms, currents, etc

• Global warming: Increase in average temp over earth over time

• IPCC: intergovernmental Panel on climate change (1988) created by UN with 3,000 scientists worldwide

Increasing CO2 concentrations

• Keeling Curve (began in 1959)

  • First to accurately measure CO2

  • CO2 levels vary seasonally and increase overall

• Seasonal fluctuation: vegetation; most of it in N hemisphere so overall there is a huge decrease in spring/summer

• Latitudinal difference: 90% of world pop in N hemisphere; 67% of world land

  • Phytoplankton produce >40% of world’s oxygen

• Increases overall because of: increased emissions from fossil fuel combustion; net destruction of vegetation

Temperature Increases

• Global temperatures have increased on average 1.4 F

• 45% of the northern ice caps have melted

Changing Species Compositions

Proxy Data: preserved physical characteristics of the environment that can stand in for direct measurement

• Observe annual ice layers, annual sediment vares, annual tree rings , annual coral bands, pollen spores

Foraminifera

• Difference species prefer different temps; very narrow range of tolerance; fossilizes well; sedimentary layers of ocean floor

Ice Cores

• Data from 500,000 years

• Air bubbles trapped each year as layers of ice laid down

• Ice in warmer temps have more O-18 isotope

• For 1/2 mil years, CO2 has never been above 300 ppm; last 60 has risen to >400

• Methane + N2O levels also increased

The Poles and Positive Feedback loop

• Poles warm the ice, snow will melt= less solar radiation will be reflected by white surfaces back into space= more solar radiation is absorbed in polar regions and they will warm faster

• As the snow/ice melt= loss of habitat for organism

• Thawing of polar areas also leads to the decomposition of large quantities of frozen biomass = releases methane and further adds to the increased rate of climate change

What causes CO2/temp shifts before humans?

• Path of orbit/position relative to sun

• Orbital tilt

• null

9.6 Ocean Warming

Polar Ice melting

• Sea level rise

• Polar bear habitat

Glaciers melting

• Lack of water supply

Permafrost melting

• Lakes drain deeper into ground, lose water

• Cause erosion with loss of structural support

• Organic matter decomposes, releases methane

Climate Change in the Oceans

• As global air temp increase from excess GHG, ocean temperatures increase

• Many marine animals are dependent on the temp of the water to regulate the temp of their bodies

  • Temp of ocean increases> organisms subject to extreme metabolic stress and may not be able to metabolize food/reproduce

9.7 Ocean Acidification

• CO2 dissolves in water to form H2CO3 (carbonic acid)

  • CO2 + H2O + CO3 = 2 HCO3

  • 1. Carbon dioxide from the atmosphere is absorbed by the ocean

  • 2. Carbon dioxide reacts with seawater to form carbonic acid; seawater pH is lowered

  • 3. Hydrogen ions released by carbonic acid bind to carbonate to form bicarbonate; carbonate concentrations are decreased, making it difficult for shell forming species to form calcium carbonate

• Dissolves shells/skeletons of marine organisms (crustaceans, molluscs, coral)

Sea Level Rise

• Increasing 3.4 mm per year

• Has risen by 9 in

• By 2100; 7-23 in more

• Total volume increases as land ice melts

• Water expands as it gets warmers (thermal expansion)

  • Effects: flooding of coastal nations and towns, saltwater intrusion into aquifers, increased erosion 

  • 100 mil people live within 3 ft of sea level

Effects on organisms

• Ranges have shifted toward both poles

• Plants flower earlier, birds migrate earlier, insects emerge earlier

• Coral bleaching: range of temp tolerance is small (is not related to ocean acidification)

• Fragmentation that can prevent migration

Future Effects

• Heat waves: increased energy demand, risk of death to poor and elderly, damage to crops and increased irrigation needs

• Cold spells: some may have positive effects, expands range of pest species

• Precipitation patterns: when there's less, crops require more irrigation; when there's more, there is flooding, landslides, erosion

• Storm intensity: ocean warming causes more hurricanes

• Ocean currents: thermohaline circulation- freshwater dilutes ocean, stops saltwater from sinking near greenland

• Effects on humans: relocation/climate refugees; health> heat waves, infectious diseases; tourism> snow, coral reefs

How might climate change have positive effects?

• Fewer deaths, crop damage due to cold

• New habitats become hospitable to humans

• Higher rainfall recharge aquifers, grow crops

Precautionary principle

1. Reduce emissions BY: increase fuel efficiency, renewable energy

2. Carbon sequestration BY: returning agricultural land to pasture/forest; capture CO2 from emissions and pump underground or into ocean

9.8 Invasive Species

Species introduction

• invasive species is any organism that is living outside of its natural habitat.  Some species are able to thrive in habitats they are introduced to and can directly compete with native species.

• Invasive species are often generalist, r-selected species and can out-compete native organisms.  In some cases, this can be catastrophic for native ecosystems. Most of the time invasive species are closely tied to humans and utilize human movement to invade new territories. These species often thrive in ecosystems that are similar to the ones that they developed in.  

Strategies for Control

• A variety of strategies have been developed to control the spread of invasive species that are specific to that organism. 

  • Prevention:  State and country borders are often heavily guarded against the import of vectors that could contain these organisms. Vessels are often decontaminated before entering new areas to prevent spreading. 

• Once organisms are introduced, it can be very difficult or impossible to control their spread. In most cases, the organisms have to be sought out and removed.

Zebra mussels

• mall freshwater mussel native to Russia.  It was accidentally introduced on ships and fishing equipment to lakes and rivers around the world and able to establish in great numbers. Adult zebra mussels can survive for weeks out of the water and would be able to travel on equipment from one lake to another with ease. 

• The U.S. has labeled them an invasive species and put in place regulation to decontaminate boating equipment to prevent further spread. The current infestations have caused millions of dollars in damage due to causing the crash of local species of shellfish as well as spreading deadly bird flu

Cane toad

• large completely terrestrial (land-based) toad native to South and Central America. They were introduced to many tropical islands and Australia on purpose with the idea that they could control beetle numbers on sugar cane farms.  In 1937 Australia introduced over sixty thousand toads to their sugar cane farms. The toads were not successful in controlling the beetle population and instead due to their opportunistic feeding habits decimated native species. The large, fast-breeding toads spread quickly across the country as they did in Hawaii, Puerto Rico and many other tropical habitats. In addition to eating and out-competing smaller native species, cane toads are poisonous and are deadly to predators. 

• The removal or control of cane toad populations has so far been unsuccessful. Traps are likely to catch similar native organisms and would cause more damage than good. Scientists have proposed methods of introducing sterile males that would compete with wild males and in turn drive the population down.  However, the majority of control now is conducted by human removal of toads.

9.9 Endangered Species

9.10 Human Impacts on Biodiversity

Biodiversity is the variety of life in a given area.  Some ecosystems or geographic areas are a host to great biodiversity, like coral reefs and rainforest. These places have many different species of plants and animals all living closely together. While other places naturally have less biodiversity, human activities, especially farming, have created large areas with very little diversity.  

One of the most prominent examples is the rainforest being cut down and replaced with rows and rows of palm trees to farm palm oil. These monocultures can not support the diverse animal life that once lived in the area. Destruction of habitat is the most pressing threat to biodiversity but it is not the only one. The major factors causing a decrease in biodiversity can be abbreviated as HIPPCO:

·      Habitat destruction

·      Invasive species

·      Population growth

·      Pollution

·      Climate change

·      Over exploitation

Conservation

•  preserving the complex relationships that naturally exist. The best way in which to do so is to preserve habitats. Some of the ways this has been accomplished is promoting sustainable land use or restoring land. In addition, fragmented sections of preserved habitat can be connected with wildlife corridors allowing genetic diversity to flow throughout populations. 

• Currently, scientists have documented around 2 million species however they believe that there are likely 8 million or more different species of plants, animals, and fungus.  Without preserving natural ecosystems there will be no way to tell the rate of biodiversity loss with human impact. Currently, we are believed to be in the 6th mass extinction event the Earth has seen.  It is estimated that over half of the populations of animals living on Earth in the 1970s are gone