Unit 8.1: Sources of Pollution

Categories of Water Pollution

• Point Source

  • Pollution that enters the environment from a single source and is clearly identified 

  • Source include:

    • Wastewater treatment plants

    • Electronic or automobile manufacturers 

    • Paper or pulp mills 

    • Oil refineries 

    • Concentrated animal feeding operations (CAFO)

    • Leaking underground gasoline storage tanks

• No point Source

  • Pollution that can not be traced back to a single point or property, not from a single pipe

  • Contributions of contaminants come from many sources accumulating over a wide area and eventually reaching a level that impairs water quality 

  • Agricultural and residential areas can have excess chemicals such as:

    • Fertilizers 

    • Herbicides

    • Insecticides

  • Water from rain, snowmelt, and irrigation running off parking lots, roads, lawns in urban/suburban areas can be a source of

    • Oil

    • Grease

    • Toxic chemicals

  • Sediment - soil particles made of sand, gravel, and clay from improperly managed construction sites, crops and forest lands, and eroding stream banks

    • One of the most significant non point source pollutants in the US

• Categories differentiate the sources of contamination in order to manager them effectively 

• EPA sets water quality standards, and these classifications help determine protection strategies

• Ground and surface waters can be impacted by both point and non point source pollution

• Clean Water Act - requires industries of point sources to get a permit form that state and/or EPA before they can discharge any effluent into a body of water

Unit 8.2: Human Impacts on Ecosystems

• Coral reefs are important ecosystems 

  • Critical ecosystems in the oceans cover less than 1% of the area but support 25% of marine species

  • Animals that live symbiotically with algae that photosynthesize

• Destructive Fishing Practices

  • Bottom Trawling scrapes nets along the ocean floor and breaks and crushed coral

  • Marine Debris like unattended nets, traps, and monofilament fishing line can damage and injurie reefs and reef-dependent organisms like young fish

  • Overfishing removes fish, especially herbivores, which help maintain healthy algae populations in the reef ecosystem 

  • Cyanide fishing is when sodium cyanide is poured over an area to stun fish so they are easier to catch for the aquarium and restaurant trade, which poisons corals

• Sedimentation Threatens Coral

  • Sedimentation, such as rock, clay, and sand, can bury corals, blocking the sunlight needed by the symbiont so no photosynthesis occurs, again resulting in the death of the coral 

• Rangle of Tolerance - based on environmental condition and number of individuals in a population 

  • The optimal range is where reproductive growth, and maintenance is at its best, so there are the most population individuals there

• As ocean temperature rises, this can cause a reprocess called coral bleaching to occur, where the coral ends up dying

• Oxygen sag curve is a ploy of dissolved oxygen levels versus disgrace from a source of pollution with excess nutrients 

• Dissolved oxygen increase when biological oxygen demand decreases, and vice versa

• Oil Spills

  • Oil spills are always a risk, and can happen with oil tankers, pipelines, rail cars, and extraction sites 

  • Oil that floats on the surface of the water can coat the feathers of birds, robbing them of both insulation and the ability to fly 

  • The fur of marine mammals like seals and sea otters can become saturated with oil, inhibiting their waterproofing and ability to maintain their body temperature 

  • They can ingest the hydrocarbons as they they try to groom the oil from their fur, and like all organisms that ingest or inhale hydrocarbons, die from poisoning 

  • Entire food chains are impacted by oil spills

    • Organisms at the bottom of the oil can die from oil ingestion, as oil blobs don’t break up

  • Coastal economies are also impacted 

  • Sediments in water can reduce light for aquatic plants, inhibit visual predators, and smother eggs and larvae aquatic organisms 

• Heavy metals in drinking water can cause health issues, such as 

  • Lead

  • Arsenic

  • Cadmium

  • Mercury

    • Causes neurological damage 

    • Happens most often through eating fish or other aquatic organisms 

    • In wastewater, there mercury is converted into a bacteria called methylmercury, which can also cause birth defects

  • Copper

  • Chromium

• Plastic waste is a threat to wildlife

  • Ingestion of litter has no nutritional value, and can block feeding tubes, leading to starvation of organisms

  • Entanglement and suffocation of plastic and nets can kill marine organisms

  • Litter can also cause toxins

    • Microplastics are tiny, degraded plastic particles and fibers that can contribute toxins to the environment in two ways:

      • The release of endocrine-disrupting chemicals like BPA added to plastic polymers when they are produced

      • Chemicals like pesticides cling to the tiny particles and are then infested by plankton and other organisms 

Unit 8.3: Endocrine Disruptors

• Endocrine Disruptors - a group of diverse chemicals 

  • Synthetic Chemicals used as 

    • Industrial solvents/lubricants and their byproducts 

      • Polychlorinated biphenyls (PCBs)

      • Polybrominated biphenyls (PBBs)

      • Dioxins 

    • Plastics and plastic Wes

      • Bisphenol A (BPA)

      • Phthalates

    • Pesticides and fungicides 

    • Pharmaceuticals

  • Natural Chemicals in food

    • Phytoestrogens found in soy

• Any chemical that interferes with the production, transport, metabolism, or function of hormone in bodies in the endocrine system

• Cell signaling is disrupted

  • Endocrine Disruptors can mimic the structure of a signaling chemical that would normally bind with a cell receptor to trigger a cellular response

  • Endocrine disruptors can also block the signal from reaching the receptor or block the transduction cascade

  • Consequences included reproductive abnormalities, birth and developmental defects, or possible behavioral changes 

• There can be exposure to chemicals through spills or toxic waste

• Exposure of endocrine disruptors are very consistent in aquatic life

  • These chemicals can enter waterways and bioaccumulate in organisms and biomagnify in the food chain so that top-level consumers are most impacted 

• This disruptors can also affect the male reproductive organs 

Unit 8.4: Human Impacts on Wetlands and Mangroves

• Wetlands - defined as having water covering the soil or is near the surface of the soil for all or most of the heat 

  • Coastal or tidal wetlands have fluctuating salinity and water levels as they are influenced by the tides

  • Inland orb on tidal wetlands are along rivers and floodplains, in depressions or low-lying areas near lakes and ponds and often have a seasonal nature to them

• Filtration improves water quality

  • Water can move slowly in wetlands, giving sediment, nutrients, and pollutants time to drop out of suspension in the water column to the bottom of the wetland

  • Pollutants can stick to soil particles or be taken up by plants

    • Much of this is reduced as water moves out of wetlands because of this filtering capacity 

• Flood Control

  • Wetlands act like sponges, holding water in place and releasing it slowly 

  • By slowing the movement of water, flood heights are reduced along with their erosive powers

  • Coastal shorelines are protected and stabilized

• Maintaining Water Flow During Dry Periods

  • Groundwater is recharged as water is held in wetland soils

  • This also helps maintain surface water flow during dry seasons

• Increase biological productivity 

  • Wetlands are some of the most productive ecosystem on the planet

  • Shallow water and plenty of plants allow for diverse habitats for animals and birds

  • Nutrient rich soils enhance plant growth which in turn provides food for diverse and abundant species

• Mangroves - are part of tidal wetlands 

  • Wetlands are remarkably productive ecosystems and important to our world’s biological diversity

  • Both inland and coastal wetlands can be impacted by human activities

  • Mangroves are a particularly productive and valuable type of coastal wetland 

• Threats to Wetlands

  • Development of commercial properties like restaurants, malls, airports, business offices, gas stations, etc, can be damaging to wetlands

  • Development can include filling in wetlands to build access roads, parking areas, or place utilities

  • Construction can increase sedimentation, destroy habitat, and redirect water flow

  • Wetlands Protection and Restoration Act - regulates development in wetlands in the US.

  • Dam construction restricts and reduces water flowing into wetlands by disconnecting rivers from their floodplains and wetlands 

    • This is a threat to organisms in this habitat

  • Overfishing - people harvest fish after than they can be replenished by reproduction in the population 

    • This creates imbalance in the entire food web within a wetland area

  • Excess nutrients and pollutants from agricultural and industrial operations can impacts wetlands

  • Waste management is critical

    • Management of manure, pesticides, insecticide and soil management can help protect wetlands, surface, and groundwater 

Unit 8.5: Eutrophication 

• Eutrophication- when a waterway received excess nutrients 

• Sources of Cultural Eutrophication:

  • Excess fertilizers from farm fields

  • Sewage form wastewater treatment

  • Nitrogen from animal manure

  • Phosphate from detergents

    • Materials are washed away by rain, melting snow, and irrigation into streams, ponds, and lakes

• Eutrophic Waterway - one that has high levels of algae as a result of excess nutrients, and low dissolved oxygen

  • With this overabundance of nutrients, plants, algae, and cyanbacteria (sometimes called blue-green algae) grow rapidly

• Oligotrophic Waterway - have very low amounts of nutrients, and high dissolved oxygen

• Stable Aquatic System - has a stable amount of algae, aquatic plants, and fish

  • Dissolved oxygen is high

• Eutrophic Aquatic System - a storm event washes excess fertilizer into the aquatic system 

  • The alga grow and reproduce creating a bloom

• Hypoxic Aquatic System - as the algae die they sink to the bottom where oxygen-consuming microbes digest the dead cells 

  • Oxygen is rapidly consumed reducing it to dangerously high levels

• Low oxygen levels can result in die-off of fish and other animals

  • Aquatic organisms will try to leave since they can’t tolerate low oxygen levels. If they can’t leave, they die, and this adds more waste to be digested by oxygen-consuming microbes

• Hypoxia creates dead zones 

  • Organic dead zones are areas of low oxygen in the world’s oceans and lakes caused be increased nutrient pollution

  • An oxygen sag curve is a plot of dissolved oxygen levels versus the distance from a source of pollution, usually excess nutrients and biological refuse 

Unit 8.6: Thermal Pollution

• Sources of Thermal Pollution

  • When heated water is discharged into bodies of water, it is considered thermal pollution

  • Power and industrial plants draw in water to cool machinery or products. They then discharge back into a water source

  • Other sources include

    • Soil erosion

    • Deforestation/shade reduction

    • Discharge from wastewater treatment

    • Urban runoff

• Impacts of Thermal Pollution

  • Warm water does not hold as much dissolved oxygen as colder water

  • Feeding, breeding, and migration factors could alter with thermal pollution

  • Habitats could also change 

  • When dissolved oxygen levels drop, it can lead to 

Unit 8.7: Persistent Organic Pollutants (POPs)

• Persistent Organic Pollutants are:

  • Persistent 

  • Organic

    • Often in rings, with chlorine attached to outside of rin

  • Synthetic 

  • Nonpolar

• DDT - Dichloro-diphenyl-trichloroethane

  • Insecticide Meaning if it gets into fatty tissues, it will remain in an organism 

  • POPs can travel long distance

  • Colorless crystal

  • Banned for use in United States

• PCBS - Polychlorinated biphenyl

  • Industrial fluid/chemical

  • Yellow liquid

  • Banned for use in United States 

• POPs contaminate water and soil

  • Clean Water Act

  • Safe Drinking Water Act

  • RCRA - Resource Conservation and and Recovery Act

  • CERCLA - Comprehensive Environmental Response, Compensation and Liability Act

  • Stockholm Convention 

    • All legislation used to regular use of POPs

• POPs are fat-soluble 

  • Accumulate over time

• POPs can travel long distances and can have local and global impact

Unit 8.8: Bioaccumulatiom and Biomagnification

• Bioaccumulation - the gradual accumulation of substances, such as pesticides or other chemicals, in an organism 

• Organisms lower on the food change accumulate pollutants into their fatty tissues 

  • Substances that bioaccumulate 

    • DDT

    • Methylmercury 

    • PCB

      • These are persistent 

      • These substances bioaccumulate in fatty tissue

• Biomagnification - the rise of increase of contaminated substances caused by intoxicating the environment 

  • Levels of Mercury increase up the food chain

• Consumption along a food chain/web increases the concentration of the substance in the fatty tissues of organisms at each successive trophic level

• Apex predators suffer the greatest effects of these substances because bioaccumulation has concentrated the substance in their fatty tissues

  • Many common apex predators include birds and raptors 

    • Humans are also considered apex predators 

    • Humans can suffer learning disabilities, kidney/liver dysfunction, damage to reproductive/circulatory/nervous systems, birth defects 

  • Apex predators can suffer developmental deformities and eggshell thinning, specifically from DDT

Unit 8.9: Solid Waste Disposal 

• Municipal Solid Waste - produced by households, businesses, etc

• Paper is the largest category of solid waste 

• E-Waste - electronic waste, any waste that needs electricity to function

  • Often contain toxic metals like mercury and lead, and other persistent pollutants 

  • Clean Water Act and Safe Water Act ensures that e-waste does not end up in our drinking water

  • RCRA - Resources Conservation and Recovery Act

  • CERCLA  - Comprehensive Environmental Response, Compensation and Liability Act

• Open Landfill

  • Odor

  • Poor contaminant of solid waste and leachate

  • Flammable

  • Animal disturbances

  • Low aesthetic value

• Sanitary Landfill

  • Liner (clay, plastic)

  • Garbage

  • Leachate and methane (CH4) collection/monitoring systems 

  • When full: cap and continuous monitoring 

• Anaerobic decomposition produces methane 

• Solid waste can be incinerated 

  • This means to burn it at high temperatures 

  • Pros: reduces waste, can be used as energy source

  • Cons: solid waste remains, air pollutants released 

  • This can produce air pollution

    • Clean Air Act

• Solid waste can be illegally dumped

  • Pros: does not take up large space, convenient 

  • Cons: unregulated methane/leachate emissions, emissions of pollutants associated with specific dumped items, disease

• Some countries do not use landfill very often, so they just dump it in the ocean

  • Pros: convenient, no drawbacks associated with landfills

  • Cons: impacts marine ecosystems and organisms

  • This can heavily impact marine life, with effects such as physical entanglement

    • Marine organisms can be mistaken for food, and have damage done to their digestive system 

  • Bioaccumulation/biomagnification of some toxins – symbol and just a plastic can play a part in this process

Unit 8.10: Waste Reduction Methods

• E-Waste

  • Contains hazardous metals like lead and Mercury

  • Can leach into soil and groundwater 

• Recycle waste before it goes into a landfill

  • Reduce, reuse, recycle

• Recycling takes many substances out of the waste stream, such as wood, paper, lawn waste, glass, metal, etc

  • Reduces need to mine minerals

  • Costly to pick up, further sort, truly recycle

  • Fees and fines can incentivize recycling

• Composting produces topsoil

  • Can be done individually or large scale 

  • Can include household scraps, yard waste, agricultural residues 

  • Not all household scraps can be composted

  • Can produce odor and attract vermin if not properly maintained

• Waste to Energy Plant

  • Sort waste —> some goes to recycling, rest goes to incinerator —> water is burned —> water boils —> stream turns turbine —> turbine turns generator —> electricity!

  • Reduced amount of waste in landfill

  • Some waste still produced: ash, hazardous waste, air pollution

• Methane Gas capture and use:

  • Decomposition reduces volume of waste in landfill 

  • Gas can be burned to create electricity

  • Some gas can still escape: greenhouse gas

  • Gas is low quality, requires refining

• Cap to full landfill to use as park, golf course, recreational area, etc

  • Improves aesthetic of area, can be a source of revenue 

  • Still requires monitoring 

• There are consequences to poorly managed solid waste 

  • Non recycled hazardous waste can pollute surrounding soil and water, even in a landfill

    • Heavy metal toxins: lead, mercury

    • Reduce/reuse/recycle programs can take solid waste out of the waste stream

  • Dimensional analysis is a key component of math in AP Environmental Science

Unit 8.11: Sewage Treatment

• Sewage treatment plans often contain materials flushed down the toilet and from the sink

• Sewage Treatment Plants

  • Primary Treatment 

    • Physical processes

    • Removal of:

      • Sticks

      • Rocks

      • Rages

      • Toys

      • Other large objects

    • Screening tanks are used to remove these items 

  • Secondary Treatment 

    • Biological processes

    • Bacteria perform aerobic decomposition to break down organic matter

      • Aeration

  • Tertiary Treatment and Disinfection 

    • Ecological/chemical processes

    • Removes final impurities and pollutants like nitrogen/phosphorus based chemicals

• Disinfection uses

  • Chlorine

  • Ozone

  • UV light

• Water quality is monitored at all stages

  • Clean Water Act and Safe Drinking Act lays at criteria for these things 

• Sewage Treatment Produces Waste

  • Solids removed during primary and secondary treatment must be disposed of 

    • Landfills:

      • Take up space

      • Potential groundwater contamination 

      • Methane produced during anaerobic decomposition can escape 

      • Pollution produced by transportation

    • Agricultural land:

      • Potential for bacterial infection of humans/animals that eat crops 

      • Potential groundwater/soil/plant contamination 

      • Potential for biomagnification of pollutants 

      • Potential for eutrophication in nearby waterways 

Unit 8.12: Lethal Dose 50% (LD50)

• Everything has an LD50

• Lethal Dose 50%

  • Amount of a substance that is lethal to 50% of a population of animals

  • Common unit: mg substance/kg body mass

  • Data is extrapolated to predict effects on humans

  • Examples: water, cyanide 

• Relates to biomagnification and bioaccumulation because of these lethal doses get into the fatty tissues, as it moves up the food chain it can poison organisms 

  • Helps explain outcomes of biomagnification 

Unit 8.13: Dose Response Curve

• Dose Response Curve

  • Shows data collected while testing effect a toxin/drug has on a given population

  • LD50 can be determined from graph

  • Threshold dose can be determined from graph

  • Effects of toxin/drug on humans can be extrapolated from graph

Unit 8.14: Pollution and Human Health

• Diverse Exposures

  • It can be difficult to establish a cause and effect between pollutants and human health issues, because humans experience exposure to a variety of chemicals and pollutants such as:

    • Food

    • Water

    • Air

    • Building materials and household items

  • There are health issues, however, they are clearly linked with certain environmental conditions or exposures

• Dysentery - inflammation of the intestines caused by bacteria or parasites 

  • People can experience bloody diarrhea and abdominal cramping

  • Dysentery is caused by untreated sewage in streams and rivers. Contamination can be detected by sampling for fecal form in water sources.

• Mesothelioma - exposure to asbestos, a type of insulation material, can result in this type of cancer

  • Asbestos is a natural mineral made of tiny glass like fibers that are easily inhaled. Overtime, this inflammation damages the cells lining the lungs, heart, and abdomen.

• Tropospheric Ozone Causes Respiratory Issues 

  • Ground level ozone is a secondary air pollutant that is formed from volatile organic compounds, nitrogen, oxide, and sunlight

  • EPA’s air quality index (AQI) can help communities notify people, especially those already at risk of respiratory conditions like asthma, when air quality is a threat of health level

• Lung function can be compromised 

  • Ozone can construct the muscles in our airways. This traps air in the alveoli of the lungs, causing shortness of breath.

  • Ozone can also inflame and damage airways will also making lungs more susceptible to infections

Unit 8.15: Pathogens and Infectious Diseases

• Pathogens cause disease

  • Any organism can cause a disease:

    • Viruses

    • Bacteria

    • Protozoans

    • Worms

    • Fungi

  • We call them germs or infectious agents

  • Pathogens can occur in many environments, regardless of the appearance of sanitary conditions

• Pathogens adapt

  • Pathogens can infect and spread through human populations

  • As our climate shifts, opportunities, for movement of pathogens are created

  • As equatorial type climate zone spread north and south from the equator, pathogens, and the vectors that carry them are showing up in places they’ve never seen before

• Vectors can spread pathogens 

  • Vector - an organism that can transmit diseases between humans and between animals and humans

    • Example: mosquitoes

• Pathogens cycle through environments 

  • They spread through:

    • Airborne particles 

    • Skin contact

    • Bodily fluids

    • Contact with feces

    • Touching surfaces that infected person has touched

    • Bite of a vector, like mosquito or tick

• Contaminated water can transmit disease

  • Poverty stricken areas often lack sanitary waste, disposal, leading to contaminate the drinking water, and the easy spread of infectious diseases

  • Cholera - a bacterial disease contracted from infected water

  • Severe, diarrhea and dehydration can result in death if left untreated

• Airborne droplets can transmit disease 

  • Tuberculosis - is caused by bacteria and attacks the lungs

  • Droplets from the coughs and sneezes from an infected person transmit the disease to the air, where others breathe in the pathogens 

  • Aerosols transmit disease as well 

    • Severe acute respiratory syndrome (SARS) and middle eastern respiratory syndrome (MERS) are respiratory diseases caused by coronaviruses, identified as SARS-CoV and MERS-CoV

    • The disease COVID-19 is also caused by a coronavirus and as identified as SARS-CoV-2

    • Severe respiratory diseases and pneumonia can be caused by these viruses as they spread from person a person

• Pathogen Spillover

  • When a disease originated in animals and then spreads to humans, it is called a spillover event

  • SARS-CoV ans MERS-CoV originated in bats, and then spread to animals that were closer to people, like civets and camels

  • Like these other coronaviruses, SARS-CoV-2 is thought to also have originated in bats, and the investigations continue to learn more about its transmission

• Plague is caused by bacteria

  • People contract the Sylvatic plague from the bacteria Yersinia pestis after being hit by an infected flea 

  • Feliz carry the disease are often found on mammals, particularly rodents

  • Antibiotics allow us to control the plague in humans and wildlife. It can still be a problem.

• Mosquitoes are vectors

  • They are a common factor of bacteria, viruses, and parasites that cause disease

• Zika Virus 

  • Can spread to humans by infected mosquitoes 

  • People can also contract the virus from sexual contact with an infected person

  • For most people, the disease symptoms are mild

  • If pregnant women are infected, however, the virus can cause a severe birth defect, called microcephaly and other severe fetal brain deformities 

• West Nile Virus

  • First found in the US in the late 1990: and has spread from the east coast across the country

  • The virus spread to humans and other animals, like horses, through mosquito bites

  • Most people have few and miles symptoms from the virus, such as a fever, rash, and fatigue

  • In severe cases, the virus can cause encephalitis, meningitis, and other issues of the central nervous system

• Malaria 

  • Causes by Plasmodium, a single-called parasite, there are 5 species that cause malaria 

  • It is transmitted from mosquito bites

  • The parasite infects your red blood cells and causes them to burst. If left untreated, people can develop severe complications, and die

  • Hundreds of millions of people, many children, die each year due to malaria. This is found mostly and sub Saharan Africa.