Unit 8– Aquatic and Terrestrial Pollution

Module 47: Sources of pollution, human impacts on ecosystems, and endocrine disruptors

• Point sources of pollution have single locations, while nonpoint sources have diffuse locations

  • Point source: distinct locations like factories

  • Nonpoint sources: diffuse areas that produce pollution (farming regions, suburban communities)

• Organisms differ in their tolerance to various pollutants

  • Niche= range of conditions

  • Homeostasis= ability to experience normal conditions in their bodies

  • Concentrations of pesticides impact animal systems, but they all have different tolerances

• Chemical pollutants include heavy metals and synthetic compounds that are produced naturally by human activities

  • Heavy metals:

  • Lead: Found in pipes, contaminates drinking water and children

  • Arsenic: dissolves into groundwater as a result of mining, can be filtered out, but causes cancer and poisioning

  • Mercury: comes from burning fossil fuels, undergoes chemical transformation from hg to methylmercury in lakes and damages the central nervous system

  • Synthetic organic compounds:

    • Pesticides kill other organisms, too and leach into water systems

    • Pharmaceuticals and hormones: enter bodies of water and animals

    • Military compounds: perchlorates persist for many years and affect the thyroid

    • Industrial compounds: disposed of in waterways, like polychlorinated biphenyls (PCBs) which are used to manufacture plastics, and are carcinogenic— and are being detected in animals, etc.

• Chemical pollutant impacts can be categorized as neurotoxins, carcinogens, tetratogens, allergens, or endocrine disruptors

  • Neurotoxins: impact nervous systems

  • Carcinogens: cancerous, can cause mutations

  • Tetratogens: interferes with the development of embryos

  • Allergens: causes allergic reactions

  • Endocrine disruptions: interferes with hormones

    • Can be found in wastewater and feminize animals

    • Chesapeake bay announced estrogen makes bass feminized

• Oil pollution comes from multiple sources

  • Oil spills (Exxon Valdez)

  • Drilling has accidents (Deepwater Horizon)

  • Still persistent today

  • Remediating oil spills: cleaning waterfowl by hand, containing oil, using chemicals to treat oil, burning the oil slicks, using engineered bacteria

Module 48– Human impacts on Wetlands and Mangroves, Eutrophication, and Thermal Pollution

• Humans are altering the availability of water by controlling its movement

  • Levees and dikes can protect from floods, but can reduce the fertility of surrounding lands because floodwaters no longer deposit sediments

  • Levee collapse can result in massive flooding

• Dams run across rivers

  • Create reservoirs

  • Three gorges dam

    • Took a lot of money

    • Can produce hydroelectric energy

    • Impact people, interrupt water flow and fish

      • Fish ladders can be used to solve this

  • Aqueducts hold water

    • People depend on them (Catskills Aqueduct to NYC)

    • Ensures a clean supply of water but also fragments environments

• Humans are converting salt water into fresh water by desalinization

  • Distilling water— can be expensive

  • Reverse osmosis (water is forced through a membrane at high pressure)— brine can’t be dumped onto land

• Humans are impacting wetlands and mangroves through development, dams, overfishing, and pollutants

  • Wetlands provide many benefits that are taken away

  • ½ normal wetland amount

• Aquatic ecosystems are being harmed by eutrophication and sediment outputs

  • Excess nutrients= eutrophication

  • Algal blooms= excess phosphorus and nitrogen

  • Oxygen sag curves: the relationship of oxygen concentrations to the distance from a point source of decomposing sewage or other pollutants

  • Sediments: prevent organisms from photosynthesis, needs to be dug up/ dredged, makes water more shallow

• Thermal pollution comes from warming water bodies while noise pollution comes from human sounds

  • Thermal pollution: when forests are logged, more sunlight reaches taters, and can kill species (thermal shock)

  • Electric power plants also return heated water (EPA mandates this and some use cooling towers)

  • Noise pollution: sonar equipment, ships, Navy sonar equipment affects whales and stuff

Module 49– Persistent organic pollutants (POPs), Bioaccumulation, and Biomagnification

• Some chemicals can persist in nature and harm ecosystems for years

  • Chemical persistence= how long it remains in environment

  • High concern: PCBs, which General Electric has dumped and needs to dredge up, PFAS= nonstick chemicals, known as forever chemicals (only filtered out)

• Concentrations of chemicals experienced by organisms depends on routes of exposure and solubility

  • Routes of exposure: air, water, soil, food

  • Solubility: how well it dissolves (percolates into groundwater, or bound to soil)

• Bioaccumulation and biomagnification can dramatically increase the concentration of a chemical in organisms by storing them in fat

  • Bioaccumulation= more storage over time

  • Mercury in fish

  • Biomagnification= when it moves up the food chain

  • Mercury in us

  • Things like DDT are high in birds now because birds eat contaminated fish

Module 50– Solid waste disposal

• Solid waste pollution has increased over time from residences, businesses, industries, and Agricultural activities

  • Municipal solid waste

  • Comes from organic items, fibers, plastics

  • Enter the waste stream

  • Composition: paper and paperboard, food, metals, plastics, etc.

  • Electronic waste: chemicals like mercury can leach out from landfills, so there is separate recycling

• Landfills are the primary destination for municipal solid waste

  • Historically we used open landfills

  • Landfills: decomposition produces methane and carbon dioxide, also leachate

  • Sanitary landfills are created w/ clay liners

• Incinerators reduce sold waste by burning it

  • Less volume, combustion gases are passed through filters

  • Waste-to-energy: heat is used as an energy source

  • Expensive to build and operate, might not burn everything

• A lot of solid waste ends up in the ocean

  • Great pacific garbage patch

• Hazardous waste requires proper handling and disposal

  • Solid, liquid, gaseous, or sludge waste material that is harmful to ppl, ecosystems, and materials

  • Is corrosive, ignitable, reactive, and toxic

• Disposing:

  • Sorted into categories and sent for treatment

  • Avoid creating waste in the first place

  • Coal ash and mine tailings are also hazardous

• Regulation:

  • Resource Conservation and Recovery Act

  • Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA/ Superfund)

    • Taxes chemical and petroleum industries and uses those funds to clean up hazardous waste

    • Love canal

  • Brownfields— contaminated commercial sites that require cleanup, but there are so many

Module 51– Waste reduction Methods

• Reduce, reuse, recycle

  • Reduce (best approach)— lessen use

  • Reuse— cleaning has to be factored in, but better than remanufacturing

  • Recycling— closed (same product) and open loop (different product) also requires extra energy but doesn’t deplete resources

• Composting reduces food and yard trimmings in the waste stream and enhances soil quality

  • Helps provide carbon/ nitrogen and reduce amounts of organic matter in landfills, reducing emissions

• New ways to think about MSW

  • Life-cycle analysis— consider how we can modify the design to be its most sustainable

  • Integrated waste management— An approach to waste disposal that employs several waste reduction, management, and disposal strategies to reduce their costs and reduce the environmental impact of MSW.

Module 52– Sewage treatment

• Wastewater pollution is caused by oxygen demand, nutrient release, and disease-causing organisms

  • Oxygen demand/ biochemical oxygen demand— more microbes demand more oxygen

  • Nutrient release/ cultural eutrophication— algal blooms, dead zones

  • Disease-causing organisms: pathogens, hepatitis, viruses, cholera, e-coli, etc

  • Monitoring for wastewater contamination: scientists monitor fecal coliform bacteria which indicates potentially harmful microorganisms

• We have modern technologies used to treat wastewater

  • Septic systems

    • Separates into 3 layers: sludge (disposed of), septage (goes through leach field), and scum

  • Sewage treatment plants

    • Debris is filtered out

    • Primary treatment: sludge settles to the bottom and is thickened and removed

    • Secondary: bacteria break down organic and inorganic material and settled particles are added to sludge

    • Tertiary: exposure to chemicals/ ultraviolet light kills pathogens and water is released into rivers or lakes

    • Thickened sludge is burned, used as fertilizer, or taken to a landfill

    • Sewage dumping/ overflow still happens b/c rainstorms and old systems

    • Animal feed lots and manure lagoons: rubber lining that prevents leakage, but risks still exist

Module 53– Lethal dose 50% and Dose-Response Curves

• Scientists can determine the concentrations of chemicals that harm organisms

  • Dose-response studies expose animals/ plants to chemicals and look at their responses over a short (acute) and long (chronic) period of time

  • LD_50 is the lethal dose of a chemical that kills 50% of individuals

  • ED_50 is the does that causes 50% of the individuals to display a harmful, not lethal, effect

  • Looks like an s-shaped graph

• We can estimate potential harm using risk assessment, acceptance, and management

  • Assessment: qualitative/ quantitative judgements based on probability of exposure * probability of being harmed

  • EPA performed a risk assessment on PCBs

  • Acceptance: the level that can be tolerated (subjective)

  • Management: trade offs, managing both things

• Worldwide standards of risk are guided by two philosophies

  • Innocent-until proven guilty= prove harm before chemicals are restricted (harmful chemicals need to be proven, so do beneficial ones)

  • Precautionary principle= chemicals need to be tested before proven good (prevents good and bad chemicals)

  • International agreements: Stockholm convention agreed on 12 chemicals to be banned, phased out, or reduced

  • REACH= Registration, Evaluation, Authorization, and Restriction of chemicals

Module 54– Pollution: Human health, pathogens, and infectious diseases

• We can establish cause and effect between pollutants and human health using retrospective and prospective studies

  • Both have downsides and upsides (missed info, selection bias etc)

    • Synergistic interaction: two risks cause more harm than expected

• Human diseases can be infectious (pathogen) or noninfectious (cancer)

  • Risk factors for chronic disease depend on national income (over/underweight, etc)

  • As nations transition to development, some risks decrease and others increase

• Many pathogens have been historically important

  • Epidemics/pandemics

  • Plague, Malaria, Tuberculosis

• Emergent infectious diseases pose new risks to humans

  • HIV/AIDS (chimpanzees)

  • Ebola (fruit bats)

  • Mad Cow Disease (Prions)

  • Swine (H1N1 pig virus)/ Bird flu (H5N1)

  • SARS, MERS-CoV

  • Covid-19

  • West Nile virus (among birds, from mosquitoes)

  • Lyme disease (ticks)

  • Zika virus (mosquito)

  • Future challenges: new disease, resistance

• Laws exist to protect human health from pollutants and pathogens

  • Clean Water Act

  • Safe Drinking Water Act

  • Minimal legislature in the developing world