Environmental Pollution and Health

8.1 Sources of Pollutants

• Point Source: A single, identifiable source of pollution (e.g., smokestack, discharge pipe).

  • Examples:

    • Animal waste runoff from a CAFO (Concentrated Animal Feeding Operation): releases ammonia ($N$) and fecal coliform bacteria.

    • Emissions from a coal power plant smokestack: releases carbon dioxide ($CO<em>2$), nitrogen oxides ($NO</em>x$), sulfur dioxide ($SO_2$), and particulate matter (PM).

    • BP Oil Spill releases hydrocarbons and benzene.

• Nonpoint Source: Diffused sources of pollution, making them difficult to identify (e.g., pesticide spraying, urban runoff).

  • Examples:

    • Urban runoff: contains motor oil, nitrate fertilizer, road salt, and sediment.

    • Pesticides sprayed on agricultural fields: carried by wind and washed off into bodies of water.

Pollutants vs. Pollution

• Pollutants: Specific chemicals or groups of chemicals from specific sources with specific environmental and human health effects.

  • Important for Free-Response Questions (FRQs). Include:

    • Specific pollutant names.

    • Their sources.

    • Their environmental and human effects.

    • Their mitigation strategies.

• Pollution: A vague, nondescript term for any substance harmful to the environment.

  • Never acceptable on an AP Environmental Science FRQ.

  • Exceptions: Specific categories of pollution - Thermal pollution, noise pollution, sediment pollution.

8.2 Human Impacts on Ecosystems

• Range of Tolerance: Organisms have a range of tolerance for abiotic conditions in their habitat such as pH, temperature, salinity, sunlight, and nutrient levels.

• Impact of Pollutants: Pollutants cause physiological stress, including:

  • Limited growth.

  • Limited reproductive function.

  • Difficulty respiring (breathing), potentially leading to asphyxiation (suffocation).

  • Hormonal disruption.

  • Death (if pollutant concentration is high enough).

pH Tolerance

• Acid Rain Effects: As pH decreases (becomes more acidic) outside a species' optimal range, the population declines.

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

  • Aluminum toxicity.

  • Disrupted blood osmolarity (sodium/chloride balance disrupted at low pH).

• Indicator Species: Aquatic species have different pH tolerances and can be surveyed to determine ecosystem conditions (soil, water, etc.).

  • Example:

  • White moss/filamentous algae indicate pH < 6.0. High crustacean population indicates pH > 6.0

Temperature Tolerance of Reef Algae

• Coral Reefs: Mutualistic relationship between coral and photosynthetic algae (zooxanthellae); algae supply sugar, coral supply $CO_2$ + detritus (nutrient-containing organic matter).

• Temperature Sensitivity: Algae have a narrow temperature tolerance and leave the reef when the temperature rises.

• Coral Bleaching: Coral loses color, becomes stressed, and is vulnerable to disease without algae (main food source).

• Other Pollutants: Runoff pollutants (sediment, pesticides, sunscreen) can also force algae from the reef.

Human Impacts on Coral Reefs

• Greenhouse gas emissions warm ocean temperatures, leading to coral bleaching.

• Urban and agricultural runoff damages coral reef ecosystems.

  • Sediment pollution: increases water turbidity, reducing sunlight (photosynthesis).

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

  • Nutrients (phosphorus/nitrogen): ammonia from animal waste, nitrates/phosphates from agricultural or lawn fertilizers.

  • Overfishing decreases fish populations.

  • Bottom trawling can break reef structure and stir up sediment.

Oil Spill Effects

• Hydrocarbons in crude oil (petroleum) are toxic to many marine organisms, especially if ingested or absorbed through gills/skin.

• Other Physiological Effects:

  • Decreased visibility and decreased photosynthesis due to less sunlight.

  • Oil sticking to bird feathers and fur of marine mammals.

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

• Economic Effects:

  • Oil washing ashore decreases tourism.

  • Kills fish, decreasing fishing industry revenue and hurting restaurants.

  • Oil can settle deep in root structures of estuary habitats like mangroves or salt marshes.

    • Can be toxic to salt marsh grasses, leading to coastline erosion and loss of breeding grounds for fish and shellfish.

Oil Spill Cleanup

• Oil spills occur when an underwater oil well explodes/blows out or when a tanker is punctured.

• Cleanup Methods:

  • Booms on the surface to contain the spread and ships with vacuum tubes to siphon oil off the surface.

  • Physical removal of oil from beach sand and rocks with towels, soaps, shovels.

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

    • Clears the surface but can smother bottom-dwellers; dispersant chemicals may be harmful.

    • Burning oil off the surface.

8.3 Endocrine Disruptors & Industrial Water Pollutants

• Endocrine Disruptors: Chemicals that interfere with the endocrine (hormonal) systems of animals.

  • Bind to cellular receptors for hormones, blocking the hormone's effect or amplifying it.

  • Human medications that pass through urine into sewage are a common source.
    Example: 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, even feminization (development of eggs in the testes or ovary formation).

• Examples:

  • Atrazine: herbicidet applied to agricultural fields, runs off into local surface or groundwater, or is carried by wind, potentially contaminating human well-water or entering the body via unwashed produce.

  • DDT: insecticide that was phased out but still persists in the 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 dumping of trash, or chemical waste, landfill leaching, or found in some cosmetics and plastic food containers (#3 plastic & “fragrance”).

  • Lead, arsenic, mercury: heavy metals.

Mercury

• Naturally occurring in coal; released by anthropogenic activities:

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

  • Attaches to particulate matter (PM) released by burning and deposits in soil/water wherever PM settles.

    • Can be released if coal ash stored in ponds overflows and runoff occurs.

  • Endocrine disruptor: inhibits estrogen and insulin (interferes with menstrual cycle and ovulation).

  • Teratogen (harmful to developing fetuses): can accumulate in the fetus brain; pregnant women can reduce risk by eating less seafood.

  • Mercury itself isn’t toxic, but bacteria in water sources convert it to methylmercury which is highly 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 still linger in soil, wood treatment chemicals to prevent rot, coal combustion & ash. Carcinogenic (lungs, bladder, kidneys) & endocrine disrupting and Can be removed with water filters

• Lead: Found in old paint (in homes), old water pipes, and soils contaminated by PM from vehicle exhaust before lead was phased out of gas in 70s; Also released in fly ash (PM) of coal combustion and it's a Neurotoxicant (damages central nervous system, especially in children) ; Endocrine disruptor and it Can be removed with water filters

Coal Ash

• Coal ash can be a source of mercury, lead, and arsenic and it Can attach to fly ash (PM) from smokestack and be carried by wind, deposited in ecosystems far away. Fly and bottom coal ash are often stored on site in ponds, dug into soil & lined with plastic (sometimes). Ponds can leach into groundwater, contaminating it with arsenic, lead, mercury and Ponds can overflow & runoff into nearby surface waters & agricultural fields.

4.6 Watersheds

• All the land that drains into a specific body of water (river, lake, bay, etc.), Determined by slope; ridges of land divide watersheds (diff. runoff directions) & Vegetation, soil composition, slope play a large role in how watersheds drain

• Watershed Characteristics: Area, length, slope, soil, vegetation types and divides with adjoining watersheds.

• Human activities impact water quality

  • Ex: ag, clearcutting, urbanization, dams, mining

Chesapeake Bay Watershed

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

• Ecosystem Services:
  Tourism revenue (hotels, restaurants, permits) & Water filtration (grass roots trap pollutants)
  Habitats for food sources (fish & crabs) & Storm protection (absorbing & buffering floods)

Human Impacts on Chesapeake Bay

• Nutrient pollution (N & P) leads to eutrophication in the Bay

  • Major N/P sources:
    Discharge from sewage treatment plants (N/P levels from human waste) & Animal waste from CAFOS
    Synthetic fertilizer from ag. fields & lawns

• Other major pollutants:
  Endocrine disruptors (from sewage treatment) & Sediment pollution (deforestation, urbanization, tilling ag. fields)

Direct Effects of Clearcutting

• Increased soil & stream temp. and Soil Erosion

Solutions to Watershed Pollutants

• Riparian buffers & Enhanced nutrient removal
  Animal manure management & Cover crops and Septic tank upgrades

8.4 Human Impacts on Wetlands and Mangroves

• Wetlands An 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 of Wetlands

• Provisioning: habitat for animal & 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 fees, ed/med research

Threats to Wetlands

Pollutants - nutrients (N/P), sediment, motor oil, pesticides, endocrine disruptors. Water diversion upstream for flood control, agriculture, or drinking water can reduce water flow and dry up wetlands Overfishing: disrupts food web of wetlands (decrease in fish predators, increase in prey). Development - wetlands can be filled in or drained to be developed into homes, parking lots, stores, or agricultural land

Benefits of & Threats to Mangroves

• The main drivers of mangrove loss are Climate change, Agriculture, Coastal development, Logging, Pollution and Aquaculture.

8.5 Eutrophication

• Process: Extra input of N & P and Algae eventually die-off; bacteria that break down dead algae use up O2 in the water
  Lower O2 levels (dissolved oxygen) in water kills aquatic animals, especially fish which fuells algae growth as a Algae bloom covers surface of water, blocking sunlight & killing plants below surface . Bacteria use up even more O2 to decompose dead aq. animals

• Anthropogenic sources: N & P from Discharge from sewage treatment plants, Animal waste from CAFOS, and Synthetic fertilizer from ag. fields & lawns.

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

• Dissolved Oxygen & Dead Zones Decrease in dissolved oxygen (hypoxia) is what causes a dead zone (DO)

Specific Factors required for life

• All aq. life requires DO (dissolved oxygen) in water for respiration & Most fish require at least 3.0 ppm to survive, 6.0 ppm to reproduce

8.6 Thermal Pollution

• Solubility of Oxygen & Temperature Solubility = the ability of a solid/liquid/gas to dissolve into a liquid (oxygen dissolving into water in this case)

• As water temp. ⬆ DO (dissolved oxygen) ⬇ and 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 which leads to suffocation

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 & Urban stormwater runoff can also cause thermal pollution due to heat from blacktop/asphalt . Steel mills, paper mills, and other manufacturing plants also use cool water to cool down machinery & return warmed water to local surface waters. Nuclear power plants require especially large amounts of cool water to cool steam back into water & to cool the reactor core.

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

8.7 - POPS persistent organic pollutants

• Persistent (long-lasting) Organic (carbon-based) Pollutants, Synthetic (human-made) compounds that do not easily breakdown in the environment; accumulate and buildup in water & soil & Are Fat-soluble

Examples & Sources of POPs

• Examples

  • DDT (outdated insecticide)

  • PCBs (plastic/paint additive)

  • PBDEs (fire-proofing)

  • BPA (plastic additive)

  • Dioxins (fertilizer production & combustion of waste and biomass)

  • Phthalates (Plastics)

  • Perchlorates (rocket/missile fuel, fireworks)

DDT was widely used as an insecticide before phaseout in most dev. nations , Still persists in soils & sediments in aq. ecosystems and builds up in food webs
Examples Pharmaceutical compounds, Medications that pass through human bodies & into sewage release from treatment plants Persist in streams/rivers & disrupt aq. organisms’ endocrine function.
Byproduct of fertilizer production & burning of medical waste, FFs, biomass

Examples & Transport of POPs

• PCBs Additives in paint and plastics, released into aquatic ecosystems by industrial wastewater Toxic to fish, causing spawning failure and endocrine disruption Reproductive failure & cancer in humans Human exposure comes through animal products.
  Perchlorates Given off by rockets, missiles, and fireworks Especially common near military testing sites or rocket launchpads Remain in soil and can leach into groundwater or runoff into surface waters.
  POPs travel long distances through wind & water, impacting ecosystems far away Wastewater release from industrial processes, leachate from landfills or improperly buried industrial waste, fertilizer/pesticide production, emissions from burning waste/biomass Enter soil/water, eaten by animals, stored in their fat, eaten by humans or taken in via drinking water

8.8 Biomagnification

• Absorption and concentration of compounds (especially fat-soluble ones like PM) in the cells & fat tissues of organisms
  Due to the fact that fat-soluble compounds like POPs and methylmercury don’t dissolve easily in water, they don’t enter blood easily & don’t leave body in urine easily

• Leads to them building up to reach higher and 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 Begins with POPs or methylmercury in sediments or plants 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.

DDT was banned in many developed nations, but still persists in sediments of many bodies of water, Reach highest levels in top predators, esp. predatory birds like eagles & osprey Caused thinning of the eggshells in these birds & Linked to massive pop. decline of bald eagle in US, which prompted passage of Endangered Species Act (73’)

• Mercury is emitted from burning coal & by volcanoes, carried by wind, and deposited in water where bacteria convert it into toxic methylmercury
  Taken in by phytoplankton & biomagnified at higher trophic levels, Reach highest levels in top predators, tuna, sharks, whales
  Neurotoxicant: damages the central nervous system of animals & Human exposure to methylmercury & POPs comes from eating large predatory fish like tuna

8.9 Solid Waste Disposal

• Types and Sources:MSW Municipal Solid Waste and E-Waste Old computers, TVs, phones, tablets

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

Sanitary Landfills

Clay/plastic bottom liner, Leachate Collection System, Methane Recovery System, Clay Cap:
Landfills generally have very low rates of decomposition due to low O2, moisture, and organic material combination .

• Things that should NOT be landfilled: Hazardous waste, Metals and Old tires

• Things that SHOULD be landfilled: Cardboard/food wrappers, Rubber Styrofoam, plastic

Landfill Issues

• Landfills have environmental impacts like groundwater contamination and release of greenhouse gases. Not in My Back Yard.
  *Waste Incineration & Ocean Dumping Waste can be incinerated (burned) to reduce the volume that needs to be landfilled and reduce volume by 90%, but also releases CO2 and air pollutants - Ocean dumping. The illegal ocean dumping occurs in some countries with few environmental regulations or lack of enforcement. Can suffocate animals if they ingest (eat) it or entangle them so they can’t fly or swim and may starve

8.10 WASTE REDUCTION

• The Three Rs: Reducing consumption is the most sustainable, Reusing next most sustainable, Recycling processing and converting solid waste material into new products

• Recycling reduces demand for new materials and Recycling is costly and still requires significant energy and the cost for cities to sort & process. If citizens recycle items that shouldn’t be recycled increases the sorting & processing costs for the cities

• Composting:Org. matter (food scraps, paper, yard waste) being decomposed under controlled conditions, Reduces the amount of methane released by anaerobic decomposition of organic matter in landfills and Reduces landfill volume
  Should be done w/proper mix of “browns” (Carbon) to “greens” (N) ~ 30:1. Should also be aerated and mixed to optimize decomposition

• E-Waste: Waste from electronics (phones, computers, etc.) that often contain heavy metals (lead, merc, cadmium

• Waste to Energy Heat → water → steam → turbine → generator →

8.11 Sewage Treatment

Physical removal of large debris with a screen or grate , Biological breakdown of organic matter by
bacteria, UV light, ozone, or chlorine is used to kill bacteria. Ecological or chemical treatments to reduce pollutants

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

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 and
  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 & Dose Response Curve

• LD50 refers to the dose or concentration of the chemical that kills 50% of the population being studied.

  • Independent variable = concentration of the chemical & Dependent variable = response measured in org

• Dose Response Studies & LD50 Studies that expose an organism to different doses of concentrations of a chemical in order to measure the response (effect) of the organism
  The data from a dose response study, graphed with percent mortality or other effect on y-axis and dose concentration of chemical on x-axis andLowest dose where an effect (death, paralysis, cancer) starts to occur is called the threshold or toxicity threshold
  LD50 dose is usually “S-shaped” - low mortality at low doses, rapid increase in mortality as dose increases, level off near 100% mortality at high dosage

• ED50 refers to the dose concentration of a toxin or chemical that causes a non-lethal effect Example: the concentration of atrazine in water that causes 50% of frogs to become infertile , Same general “s-shape” as LD50 dose response curve, but at lower dose concentrations .

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

8.14 Pollution and Human Health

• Routes of Exposure & Synergism Routes of Exposure: Ways that a pollutant enters the human body

• Synergism : The interaction of two or more substances to cause an effect greater than each of them individually & It’s difficult to establish exactly how toxic different pollutants are to humans because we have so many routes of exposure to so many different pollutants
  Dysentery - Bacterial infection caused by food or water being contaminated with feces
  Mesothelioma (asbestos), Tropospheric Ozone (O3)) Worsens respiratory conditions like asthma, emphysema, bronchitis, COPD and ONLY HARMFUL IN TROPOSPHERE (beneficial in stratosphere)

8.15 Pathogens and Infectious Diseases

• A living organism (virus, bacteria, fungus, protist, worm) that causes an infectious disease - Living organism (rat, mosquito) that carry and transmit infectious pathogens to other organisms
  Less developed, poorer countries typically have higher rates of infectious disease - Less sanitary waste disposal, Lack of treatment/filtration for drinking water & sewage treatment, and Less access to healthcare facilities
  Plague Bacterial (pathogen) infection transmitted by fleas, Tuberculosis (TB) Bacterial (pathogen) infection that targets the lungs, transmitted by breathing bacteria from blood,Malaria parasitic protist (pathogen) infection caused by bite from infected mosquitoes. West Nile Virus (pathogen) infection caused by bite from infected mosquitoes.
  SARS (Severe Acute Respiratory Syndrome and MERS (Middle East Respiratory Syndrome)