Unit 8 Aquatic and Terrestrial Pollution

Point sources

Pollutant that enters environment from an easily identified and confined place

• CAFOs (ammonia (N), fecal coliform bacteria)

• coal powerplant smokestack (CO₂, NOx, SO₂, PM)

• BP oil spill (hydrocarbons, benzene)

Nonpoint sources

Pollutants entering the environment from many places at once

• urban runoff (motor oil, nitrate fertilizer, road salt, sediment)

• pesticides sprayed on agricultural fields

Which type of pollution (non/point) are estuaries and bays most at risk for?

Nonpoint sources from watersheds that empty into them

Pollutants cause physiological stress in organisms, like:

• Limited growth

• Limited reproductive function

• Difficulty breathing/respiring, potentially asphyxiation

• Hormonal disruption

• Death

Environmental effects of acid rain

• As pH decreases (increased acidity), outside optimal range for a species declines

• When pH leaves range of tolerance, organisms cannot survive at all, due to:

  • aluminum toxicity

  • disrupted blood osmolarity

Indicator species

Can be surveyed and used to determine conditions of an ecosystem

• high white moss/fil. algae: pH < 6.0

• high crustacean: pH > 6.0

Temperature and coral

Coal = symbiotic relationship with photosynthetic algae (zooxanthellae); algae supply sugar and coral supply CO₂ and detritus (nutrient containing organic matter)

• algae have narrow temperature tolerance and leave the reef when temperature rises

  • pollutants from runoff can also force algae from reef

• coral loose color and become vulnerable to disease without algae (main food source)

Human impacts on coral reef

• GHGs warm ocean temperature and bleach coral

• Overfishing decreases fish populations in coral reef ecosystem

• Bottom trawling can break reef structure and stir up sediment

• Urban and agriculture runoff

  • sediment pollution: sediment carried into ocean by runoff makes reed waters more turbid, reducing sunlight and photosynthesis

  • toxicants: chemicals in sunscreen, oil from roadways, pesticides from agricultural runoff

  • nutrients (P/N): ammonia from animal waste, nitrates/phosphates from agriculture or lawn fertilizers

Environmental effects of 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 through gills/skin

• Decreased visibility and photosynthesis

• Oil sticking to bird feathers

• Oil sinking to bottom and killing bottom-dwellers due to direct toxicity or suffocation

Economic effects of oil spills

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

Estuary impacts (mangroves and salt marshes) of oil spills

Oil can settle deep in root structures of estuary habitats

• can be toxic to salt marsh grasses, killing them and loosening root structures, leading to coastline erosion

BP Gulf Spill

Underwater oil well explosion

Exxon Valdez

Tanker runs into a rock/iceberg and is punctured

Oil plume

Column of oil migrating upwards through the water column after an oil spill

• can cause oil slicks

Oil slick

Thin layer of oil that flows on the surface of water after an oil spill

Oil spill cleanup components

• Boom

• Skim

• Physical removal with towels, soaps, shovels

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

• Burning

Boom (oil spill cleanup)

Long, floating barriers used to contain or prevent the spread of spilled oil

• contains spread of oil and ships with vacuum tubes to siphon oil off of the surface to skim it off

Skim (oil spill cleanup)

Boats equipped with a floating skimmer designed to remove thin layers of oil from the surface, often with the help of booms

Endocrine disruptors

Chemicals that interfere with endocrine (hormonal) systems of animals

• bind to cellular receptors meant for hormones, blocking the hormone from being fully received, or amplifying its effects

Where endocrine disruptors come from

Human medications that pass through urine and into sewage or are flushed down toilets

Atrazine (herbicide)

Binds to receptors of cells that should convert estrogen into testosterone in male frogs, leading to: high estrogen in males, low sperm count, feminization (development of eggs in the testes or ovary formation)

• used to control weeds and prevent crop loss

• applied to agricultural fields, run off into local surface or groundwater

• can contaminate human well-water, or enter body via unwashed produce

DDT

Broad-spectrum insecticide that was phased out, but still persists in environment

• applied to agricultural 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 internacional dumping of trash, or chemical waste from plastic/cosmetic factories improperly disposing of waste, landfill leaching

Mercury (Hg)

Naturally occurring in coal

• anthropogenic sources: coal combustion, trash incineration, burning medical waste, heating limestone for cement

  • attaches to PM released by burning and deposits in soil/water whenever PM settles

  • can be released if coal ash stored in ponds overflow and runoff

• endocrine disruptor: inhibits estrogen and insulin

• teratogen: chemical harmful to developing fetuses

  • can accumulate in fetus brain if eaten while pregnant

Arsenic (As)

Naturally occurring in rocks underground that can dissolve in drinking water

• anthropogenic sources: pesticides applied to agricultural fields, wood treatment chemicals to prevent rot, coal combustion and ash

• medical concerns: carcinogenic and endocrine disruptor

• can be removed with water filters

Lead (Pb)

Can be found in old paint, old water pipes, and soil contaminated by PM from vehicle exhaust before Pb was phased out of gas in the 70s

• medical concerns: neurotoxicant, endocrine disruptor

Coal ash

Can be a source of Hg, Pb, and As

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

• stored on site in ponds, dug into soil, and lined with plastic

  • ponds can leach into groundwater, contaminating it with arsenic, lead, and mercury

  • ponds can overflow and runoff into nearby surface waters and agricultural fields

Benefits of wetlands

Flood protection, water quality improvement, shoreline erosion control, natural products, recreation, and aesthetics

Wetlands

An area with soil submerged/saturated in water for at least part of the year, but shallow enough for emergent plants

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

Provisioning service of wetlands

Habitat for plant and animal foods

Regulating service of wetlands

Groundwater recharge, absorption of floodwater, CO₂ sequestration

Supporting service of wetlands

H₂O filtration, pollinator habitats, nutrient cycling, pest control

Cultural service of wetlands

Tourism revenue, fishing license, camping fees, educaitonal/medical research

Threats to wetlands

• 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 diversion upstream for flood control, agriculture, or drinking water can reduce water flow and dry up wetlands (e.g. Everglades)

  • dam reconstruction for flood control/hydroelectric reduces major water and sediment (N/P) flow to wetlands

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

Solutions to watershed pollutants

• Focus on point/nonpoint source pollution reduction

• Wastewater treatment

• Stormwater management

• Promoting sustainable agricultural practices

• Educate public on responsible waste disposal and water conservation

Eutrophication process

1. Algae bloom covers surface of water

2. Algae die; bacteria that break down dead algae use up O₂ in the water (because decomposition = aerobic process)

3. Low DO (hypoxia/low O₂)/High BOD

Positive feedback loop of eutrophication

Less O₂ → more dead organisms → more bacterial decomposition → less O₂

Cultural eutrophication

Anthropogenic nutrient pollution (N and P) that leads to eutrophication

Major N/P sources (cultural eutrophication)

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

• Animal waste from CAFOs

• Synthetic fertilizer from agricultural fields and lawns

Oligotrophic waterways

Waterways with low nutrient (N/P) levels, stable algae population, and high dissolved oxygen

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

Pond succession

Sediment buildup on bottom (benthic zones) leads to higher nutrient levels

• over time, ponds naturally shift from oligotrophic, to mesotrophic, to eutrophic

DO

Dissolved oxygen

What causes a dead zone?

Decrease in DO (hypoxia) is what causes a dead zone

• all aquatic life requires DO 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

Solubility

The ability of a solid/liquid/gas to dissolve into a liquid

Relationship between water temperature and dissolved oxygen (DO)

Inverse

• as water temperature increases, DO decreases

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)

• hot water also has less O₂

  • this can lead to suffocation without enough O₂ to support respiration

Sources of thermal pollution

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

• Urban stormwater runoff due to heat from blacktop/asphalt

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

Cooling towers/ponds

Used to cool steam back into water and to hold warmed water before returning it to local surface water

• already standard in nuclear power plants, but can be optimized to cool water better or hold it longer before returning to nearby surface waters

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: accumulate and persist in animals’ fat-tissue instead of passing through the body

  • can slowly be released from fatty tissue into the blood stream and impact brain and other organs over time (especially the reproductive system)

Common examples of POPs

DDT, PCBS, PBDEs, BPA, Dioxins, Phthalates, Perchlorates

Medications/Pharmaceuticals (POPs)

Steroids, reproductive hormones, antibiotics that pass through human bodies and into sewage release from treatment plants

• persist in streams/rivers and disrupt aquatic organisms’ endocrine function

Dioxins (POPs)

Byproduct of fertilizer production, combustion of waste (particularly medical waste)

• 90% of human dioxin exposure comes from animal fats since dioxins buildup in animal fat tissue

PCBs (POPs)

Additives in paints and plastics and from industrial wastewater

• toxic to fish, causing spawning failure and endocrine disruption

• reproductive failure and cancer in humans

  • human exposure from animal products

Perchlorates (POPs)

Military facilities, rocket fuel, missiles, and fireworks

• remain in soil and can leach into groundwater or runoff into surface waters

Sources of POPs

• Wastewater release from landfills or improperly buried industrial waste

• Fertilizer/Pesticide production

• Emissions from burning waste/biomass

• Leachate: liquid with elevated levels of pollutants as a result of having passed through municipal solid waste (MSW) or contaminated soil

Bioaccumulation

Absorption and concentration of compounds (especially fat-soluble ones like POPs) in the cells and fat tissues of organisms

• fat-soluble compounds like POPs and methylmercury don’t dissolve easily in water, they don’t enter blood easily and don’t dissolve easily

  • instead, they buildup in fat tissue

  • they build up to reach higher and higher concentrations in organisms over time

Biomagnification

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

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

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

  • secondary consumers eat primary consumers and take in the POPs in their tissues

    • 10% rule—organisms at each successive trophic level need to eat more and more biomass to receive energy, leading to higher and higher POP levels over their lifetimes (organisms higher in pyramid have higher POP levels)

Biomagnification of DDT

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

• reach highest levels in top predators, especially predatory birds like eagles and osprey

  • causes thinning of the eggshells in these birds

  • linked to massive population decline of bald eagle in US, which prompted passage of Endangered Species Act in 1973

Where does mercury come from?

Burning coal and by volcanoes

Where does methylmercury come from?

Mercury is carried by wind and deposited in water where bacteria convert it to toxic methylmercury

• neurotoxicant

Biomagnification of methylmercury

Taken in by phytoplankton and biomagnified at higher trophic levels

• reach highest levels in top predators like tuna, sharks, whales

• human exposure comes from eating large predatory fish like tuna and salmon

Municipal Solid Waste (MSW)

Solid waste from cities (households, businesses, schools, etc.)

• aka trash, litter, garbage, refuse

Waste “stream”

Flow of solid waste to recycling centers, landfills, or trash incineration facilities

• 1/3 paper

• 2/3 organics (compostable)

E-Waste

Old computers, TVs, phones, tablets

• only 2% of MSW

• considered hazardous due to metals

Dump

Where trash is dumped without features of sanitary landfills

Sanitary landfills

Where developed nations dispose of trash

• clay/plastic bottom liner

• leachate collection system

• methane recovery system

• clay cap

Clay/Plastic bottom liner (sanitary landfills)

Layer of clay/plastic on the bottom of a hole in the ground; prevents pollutants from leaking out into soil/groundwater

Leachate collection system (sanitary landfills)

System of tubes/pipes at bottom to collect leachate for treatment and disposal

Methane recovery system (sanitary landfills)

System of tubes/pipes to collect methane produced by anaerobic decomposition in the landfill

• methane can be used to generate electricity or heat coal buildings

Clay cap

Clay-soil mixture used to cover the landfill once it’s full; keeps out animals, keeps in smell, and allows vegetation to regrow

Why do landfills have very low rates of decomposition?

Low O₂, moisture, and organic material combination

Things that should NOT be landfilled

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

• Metals like Cu and Al (should be recycled)

• Old tires; often left in large piles that hold standing water ideal for mosquito breeding

Things that SHOULD be landfilled

• Cardboard/food wrappers that have too much food residue

• Rubber, plastic films/wraps

• Styrofoam

Things that can be landfilled, but should be recycled or composted

Food, yard waste, and paper

Landfill issues

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

• Greenhouse gases (CO₂ and CH₄) are released from landfills due to decomposition; both contribute to global warming and climate change

• NIMBY

• Social justice/Environmental injustice issues: landfills are often place near low-income or minority communities that don’t have the resources or political power to fight against these decisions

Not In My Back Yard (NIMBY)

Idea that communities don’t want landfills near them because:

• smell and sight

• can attract animals

• groundwater contamination concerns

  • landfills should be located far from river, streams, and neighborhoods to avoid H₂O contact

Waste incineration

• Can reduce waste volume by 80-90%

• Reduces waste volume because most waste is hydrogen, carbon, and oxygen which easily combust at high temperatures

• Bottom ash may contain toxic metals and is stored in ash ponds, then taken to special landfills

• Concerns that toxic metals will be released by combustion and leach out of storage ponds or be released into the atmosphere

• Waste can be burned to generate electricity

Illegal ocean dumping

Occurs in some countries with few environmental regulations or lack of enforcement

• garbage patches collect in ocean from floating plastic

• can suffocate animals or entangle them so they can’t fly or swim, and may starve

Reducing

Most sustainable of the three Rs because it decreases natural resource harvesting and the energy inputs to creating, packaging, and shipping goods

• ex. metal/reusable water bottle to reduce plastic use

Reusing

2nd most sustainable of the three Rs because it doesn’t require additional energy to create a product

• ex. buying secondhand clothes

Recycling

Processing and converting solid waste material into new products

• least sustainable of the three Rs

Closed loop recycling

Products are reprocessed and recyclate produced is used in the same/similar way

• ex. glass being turned into glass

Open loop recycling

Products are reprocessed and the recyclate produced is used in a different way

• ex. shoe soles being turned into track

Pros of recycling

• Reduces demand for new materials, especially metals and wood which cause habitat destruction and soil erosion when harvested

• Reduces energy required to ship raw materials and produce new products

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

Cons of recycling

• Costly and requires significant energy

• People recycling things that shouldn’t be recycled costs more to sort

National Sword (China)

Policy banning importation of certain types of solid waste

Composting

Organic matter (food scraps, paper, yard waste) being decomposed under controlled conditions

• almost 2/3 of waste is compostable

• reduces landfill volume

• produces rich organic matter that can enhance water holding capacity, nutrient levels or agricultural or garden soil

  • valuable product to sell

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

Two important factors when composting

• Proper mix of browns (C) to greens (N) 30:1

• Should be aerated and mixed to optimize decomposition (bacteria need O₂ for decomposition)

Potential drawbacks of composting

• Foul smell if not properly rotated and aerated

• Rodents or other pests may be attracted

E-waste

Waste from electronics that often contain heavy metals

• can leach these toxic metals into soil and groundwater of disposed of in landfills or open dump

• can be recycled and reused to create new electronics, but is often sent to developing nations for recycling due to health hazards, stricter environmental and worker protection laws

• can be dismantled and sold to countries that extract valuable metals from motherboards

• often dumped or burned due to less strict environmental regulations or lack of enforcement in developing nations

Waste can be incinerated to:

Reduce volume and generate electricity

• heat → water → steam → turbine → generator → energy

CH₄ incineration

• Produces electricity without fracking or mining of FFs

• Reduces landfill volume

Where does methane (CH₄) come from (waste)?

Anaerobic decomposition of waste in landfill

Water treatment process steps

Primary (physical) → secondary (biological) → tertiary (chemical) → disinfectant

Primary treatment (water treatment process)

Physical removal of large debris (TP, leaves, plastic, sediment) with a screen or grate

• first step

• screens or grates filter out large solids → grit chamber allows sediment to settle out and be removed

Secondary treatment (water treatment process)

Biological breakdown of organic matter by bacteria; aerobic process that requires O₂

• second step

• O₂ is bubbled into aeration tank filled with bacteria that break down organic matter into CO₂ and nutrients like N and P

• removes 70% of P and 50% of N

  • DOES NOT remove POPs

Tertiary treatment (water treatment process)

Chemical treatment to reduce pollutant levels (N, P, NH₃(ammonia))

• third step

• critical step because effluent that is discharged into surface waters with elevated N/P levels leads to eutrophication

• expensive and not always used

Disinfectant treatment (water treatment process)

UV light, ozone, or chlorine is used to kill bacteria or other pathogens, such as e. coli

• fourth and last step

Effluent

Liquid waste (sewage) discharged into a surface body of water, typically from a wastewater treatment plant

Sludge

Inorganic, solid waste that collects at the bottom of tanks in primary or 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