ENR 2100 (ONLINE VERSION) Intro to Environmental Science: Midterm 1 Study Guide
WEEK 1 NOTES (1/9/2017)
a. Physical environment vs. Biological environment
● Environment: specific set of physical and biological conditions in a given time and space that
support the growth, development and reproduction of life.
● Physical environment: consists of the incoming radiant energy of the sun, air, water, and soil,
which is required for life on Earth.
● Biological environment: encompasses the organic components, organisms (including humans)
and their relationships on Earth.
b. What is environmental science and what other disciplines collaborate under the umbrella of
● Environmental science: interdisciplinary study of humanity’s relationship with other organisms and
● Combined disciplines: biology, geography, chemistry, geology, physics, economics, sociology,
anthropology, resource management, agriculture, law, politics, engineering, and ethics.
c. What are some environmental challenges that we are facing on the planet today? Are there sustainable
practices to combat these problems?
● Today we have the same sense of superiority that humans before us had. This frequently
prevents us from responding effectively to environmental changes. We often don’t care to notice
signs that were are causing irreparable damage to Earth.
● Energy production and climate change
● Food production
● Air pollution
● Water quantity and quality
● Ecosystem conservation and preservation
● Mining for coal, oil, natural gas and minerals
● Hazardous waste
● Human population growth→ one of the major causes of environmental damage.
● Loss of habitat and biodiversity
● Urbanization and transportation
● Environmental inequality and justice
○ Carrying capacity=population size that an area can support indefinitely; many scientists
believe we have already passed it for Earth
○ Ecological footprint=land needed to provide resources, assimilate waste of a population
○ anthropogenic=caused by or related to human action
d. How does one’s ecological footprint affect the potential carrying capacity of their geographic location
and the entire planet? Do people have different footprints and what causes this?
● 1 person living in China has footprint of 10,000 sq m, 1 person living in USA is 100,000 sq m
● The bigger our ecological footprint, the more likely we are to exceed our carrying capacity of our
○ If every person on Earth lived like someone in the USA, we would need almost 7 Earths
to sustain us
e. Renewable vs. nonrenewable resources and examples of each
● Renewable=energy that comes from infinitely available or easily replenishable source
○ Solar, wind, geothermal
○ A sustainable ecosystem is one that makes the most of renewable energy
■ Sustainable ecosystems depend on biodiversity (variety of species present) to
harvest energy and recycle and use matter. This biodiversity includes primary producers (photosynthetic organisms), consumers, decomposers, predators,
parasites, competitors to serve as natural population checks.
○ Problem: conversion of energy; only ~10% of energy is passed from one tropic level to
● Nonrenewable=resources in finite supply or not replenished in timely fashion
○ coal, oil gas
f. Triple Bottom Line
● Environmental literacy= ability to understand environmental problems
● Environment→ broad term that describes the surroundings or conditions (biotic and abiotic) in
which any given organism exists.
g. Social Traps-seem good in short term but usually hurt in long term; Education is the best hope for
avoiding social traps
● i. Tragedy of the Commons→ shared resource that is not owned by any one person. Individuals
who try to maximize benefit hurt the resource
○ (the tendency of an individual to abuse commonly held resources in order to maximize
his or her own personal interest; example overgrazing of open ranges in USA)
● ii. Time Delay→ good today but gone tomorrow
○ Ex: Modern fishing techniques/overfishing→ depletes fish population
● iii. Sliding Reinforcer→ related to evolution and genetically modified organisms
○ actions that are beneficial today can change conditions such that benefit declines over
time (e.g., use of RoundUp on crop fields and evolution of resistant weeds).
○ Ex: use of pesticides creates large pesticide-resistant pest population emerges
h. Obstacles to sustainable practices
● lack of education→ trade-offs between short-term gains and long-term costs
● Wealth inequality→ 20% of world’s population controls 80% of Earth’s resources
i. How has the natural world changed over time?
● i. Laws and major events
○ Expansion; mid 1800s
■ General Land Ordinance, Homestead Act
○ Resource management; late 1800s-early 1900s
■ National Forest and Park Services
○ Pollution concerns; mid-late 1900s
■ Clean Air Act, Clean Water Act, Superfund Act,
○ International Effort; late 1900s-present
■ Montreal protocol (reduce CFCs use)
j. Ecosystem structure
● i. Abiotic elements→ Sun, water, land, atmosphere
● ii. Biotic elements→ Plants, microorganisms, humans
k. Conflicting world views
● Anthropocentrism; human-centered
● Biocentrism; life-centered
● Ecocentrism; system-centered
● i. How do these determine an individual’s environmental ethic?
Week 2: Lecture 1/16/17
● a. Steps of the Scientific Method. ○ 1. Recognize a question or unexplained occurrence. 2. Develop a hypothesis to explain
the occurrence. (Hypothesis=a proposed explanation for an observed phenomena). 3.
Design & perform experiments to test hypothesis. 4. Analyze & interpret data to reach
conclusion. 5. Share knowledge with scientific community and public.
● b. Understand that science is a process, limited to observations, experimental and always
○ Empirical evidence is data that is gathered through observations. Scientists collect data
objectively, meaning that the data is not biased and can be collected by anyone in the
same place, using the same equipment, etc.
● c. What is a hypothesis and be able to formulate examples.
● d. How are hypotheses generated and tested?
● e. Be able to classify a hypothesis as testable and falsifiable.
● f. What are the negative consequences of the depletion of the ozone? What harmful effects are
researchers working to combat?
○ Depletion of ozone caused by synthetic chemicals allows dangerous solar radiation to
reach the Earth’s surface
● g. Describe the process by which scientists discovered causes of ozone depletion. Are there still
unknowns that exist?
○ Beginning of data collection with on-the-ground instruments designed to extend the
researchers’ senses and measure atmospheric composition
○ First indications of lower than normal ozone levels used to make inferences about
○ Discovered that ozone layer had thinned about 33% during antarctic spring
○ Also connected to studies to data showing increases in CFCs, which produce
■ Inference that ozone depletion of the Antarctic was connected to the increased
presence of chlorine compounds produced by CFCs
● Ozone=O3, key component of atmosphere, protects us from UV radiation; component of smog at
ground level→ “bad” ozone
● Troposphere=from ground to about 7 miles up
● stratosphere=beyond troposphere up to about 31 miles up
○ Less dense than troposphere and contains ozone layer
○ Ozone in stratosphere helps maintain our “perfect” temperature on the planet
● Solar radiation= enters the atmosphere in 3 forms of UV radiation: UV-A, UV-B, UV-C; ozone in
the stratosphere absorbs much of the UV-B
○ UV-C: most energetic form of UV radiation; important in formation of ozone; would be
very harmful to life but it absorbed by O2 & doesn’t reach Earth’s surface
○ UV-B: can cause damage to DNA of living things; Ozone absorbs most of it, about 10%
reaches Earth’s surface
■ Dangers: damages cells, DNA, increased risk of cataracts, increased risk of skim
○ UV-A: least energetic; about 50% reaches Earth’s surface; can cause skin damage
● Protective Ozone in Stratosphere; absorbs UV radiation and prevents it from reaching
troposphere; less ozone in stratosphere→ More UV reaches surface of Earth→ higher skin
● Causes of Ozone Depletion in Stratosphere
○ Primary chemical responsible are CFCs ■ CFCs are very stable and only exposure to strong UV radiation can break them
■ When this happens the CFC molecules releases atomic chlorine
■ One chlorine atom can destroy 100,000 ozone molecules
■ The net effect is to destroy O3 faster than it is naturally produced
● Ozone Hole
○ A slight ozone thinning occurs naturally over Antarctica for a few months each year
○ In 1985, this thinning was observed to be greater than expected if natural causes were
the only factor inducing it
○ The holes occurs over Antarctica because strong westerly winds circulate around the
continent and create a polar vortex
○ Susan Solomon (NOAA) thought that temperature had something to do with it. She knew
that in the spring (sun over Southern Hemisphere) cold spring winds over Antarctica
produced a cyclone of cold air in the atmosphere that kept the cold air in place and led to
the formation of polar clouds in the stratosphere. 2. Solomon proposed the hypothesis
that cloud particles in the polar stratospheric clouds were providing surfaces for the
reactions that produce SCIENCE LITERACY AND THE SCIENTIFIC PROFESS free
chlorine molecules (Cl2) from CFCs. In the sunlight of spring the Cl2 would break into Cl-
atoms, which then destroy O3.
■ a. Solomon’s hypothesis predicted that the stratosphere over Antarctica in the
spring would contain high levels of chlorine monoxide (ClO) from the Cl- atoms
reacting with the O3.
■ b. To test her hypothesis, Solomon raised balloons into the atmosphere over
Antarctica in spring and measured the composition of gases in the air as well as
the amount of sunlight. i. She discovered increased sunlight = increased ClO =
decreased O3 in the atmosphere and increased uv light reaching surface of
■ C. Next, scientists wanted to know if decreased ozone leads to more skin cancer.
○ 2. Jaime Abarca and Claudio Casiccia investigated this hypothesis by evaluating skin
cancer incidence in residents of Punta Arenas, Chile, a region exposed to higher levels of
UV light due to its proximity to the ozone hole over Antarctica.
■ b. The scientists predicted higher rates of skin cancer in years were ozone
depletion was high.
■ c. To test their hypothesis they looked at skin cancer rates between 1987- 1993
and compared them to same population between 1994-2000.
■ d. Their data showed that nonmelanoma skin cancer (the most common type of
skin cancer, then type that forms in skin cells other than the cells that produce
the pigment melanin, hence the name nonmelanoma) rates were significantly
higher in times of ozone depletion.
■ i. They used statistics (mathematical evaluation of experimental data to
determine how likely it is that any difference observed is due to the variable being
tested) to high probability (at least 95%) that their conclusion was correct
(p<0.05, representing a level of certainty of 95%).
○ 3. Research by other scientists showed that UV levels had increased from 1974 to the
mid-1990s at the Earth’s surface at midlatitude regions. At the southern tip of Argentina
UV-B levels were 45% higher than normal in 1990. ○ 3. The international community came together to find a solution. In Montreal, Canada in
1987 Montreal Protocol - phase out CFCs. In 1987 only 24 countries signed the
agreement, but finally in 2009 all 196 countries signed the treaty.
● CHAPTER 2 B. The Montreal Protocol is administered by the United Nations and mandates that
governments in all 196 countries must cut back/end production of CFCs.
○ C. In the 1990s the USA decided to phase out all CFC through regulations from U.S. EPA
the federal agency responsible for enforcing environmental laws.
○ 4. Companies, like DuPont, engineer compounds to replace CFC. These new refrigerants
are called hydrochlorofluorocarbons (HCFCs) and were thought to be environmentally
safe, but now are also proving to be detrimental to the ozone layer.
○ 5. Future projections estimate that mid-latitude areas will reach pre-1980 ozone levels by
2050 and polar regions by 2075.
● h. Can we have absolute proof of something as scientists? → NO! Are conclusions open for
future studies? → YES!
● i. What are the two types of scientific studies? → Observational study vs. experiment
● j. What are the dependent and independent variables in a study? In terms of the ozone depletion
● k. Why are alternative hypotheses important in research?
● l. What are CFCs and what was concluded about them in relation to the ozone?
○ CFCs (Chlorofluorocarbons)= 1st produced in 1930s as commercial coolants; man-made;
by 1970s they were in everything from fast food styrofoam to hairspray
■ Were considered safe at the time
■ CFC molecules would remain aloft for along time and be broken apart by
UV light in the stratosphere. The released chlorine atoms would destroy ozone.
■ Older CFCs have chlorine, which destroys ozone. Bromine also destroys ozone.
These molecules are no longer produced or used in many countries.
■ Newer CFCs do NOT have chlorine, but have fluorine instead, which turns out
they destroy ozone also. These molecules are also potent greenhouse gases.
■ Sherwood Rowland and Mario Malina of UC, Irvine wondered what would
happen to a completely synthetic molecule in the atmosphere. In 1974 they
proposed that CFCs weren’t completely harmless, they realized CFCs stay aloft
for 100 years or more and once in stratosphere they would be exposed to
ultraviolet (uv) light so intense it would break them apart to release chlorine
atoms which are very reactive.
● m. How were these scientific results and conclusions translated into policy?
○ Aerosol cans (a significant source of CFCs) were outlawed
○ Montreal Protocol- phasing out dangerous chemicals such as CFCs
○ Full recovery of ozone layer is estimated to take place sometime after 2050.
Week 3 Lecture (1/26/17)- Persistent Pollutants
● Bisphenol A or BPA is a synthetic chemical from the 1940s used to line metal food cans and in
the production of plastic bottles, including baby bottles. Studies began showing an association
between BPA and serious medical conditions. BPA was banned in Canada and the U.K. Plastics
industry challenged the science claiming BPA was safe.
● a. Natural and Synthetic (man-made, anthropogenic) toxins.
○ Synthetic=persistent; don’t degrade over time
○ natural=doesn’t always mean safe; e.g. arsenic in groundwater ● b. Rachel Carson, Silent Spring, DDT
○ Highlighted significant die-off following only two decades of extensive use of DDT and
other herbicides and pesticides. DDT was doing what it supposed to do—kill pests,
including the mosquitoes responsible for malaria.
○ Had 3 specific concerns:
■ Some chemicals have large effects in small doses.
■ Certain stages of human development are especially vulnerable to effects.
■ Mixtures of different chemicals can have unexpected impacts.
● One result of the book was a movement toward stricter regulations for
chemical pesticides and a U.S. ban on DDT.
● c. Risk Assessment
○ Weigh the cost and benefits associated with any chemical
○ In reality, it is impossible to fully understand and assess all potential interactions among
the many chemicals to which we are exposed on a daily basis. Reality includes
practicality, economic forces, and the basic need for the chemical.
● “better safe than sorry”: known as the precautionary principle until exposure limits are determined
● “innocent until proven guilty”: rely on recalls rather than prevention. This leaves the burden of
proof on the public.
● d. Primary, secondary, tertiary sources.
○ Primary sources new & original information from research: rigorously reviewed by peers
in the scientific community for design, data, & analysis.
○ Secondary sources include interpretation of primary sources and lack of peer review.
This is what you read in the popular press.
■ Government and agency sources
○ tertiary→ unreliable, draws on secondary sources; may have agenda, perpetuate errors
○ i. Know the different parts of a journal article such as author, affiliation, abstract, volume,
page numbers, and corresponding author.
● e. Persistence of a substance
○ Low persistence - Break down quickly with sunlight or microbial action
○ High persistence - Long time to break down and potential environmental impact long after
■ Many synthetic compounds cannot be broken down because these are NEW
compounds. Therefore, microbes have not evolved mechanism to degrade these
● Water soluble: Often safer for humans: excrete in urine
○ Still potential toxic at high doses or continual low dose
○ High impact on aquatic organisms: easy uptake and excreted in sewer
● Fat-soluble: Cross cell membrane in humans and hard to eliminate
○ Some break down by liver
○ Storage and accumulation in fatty tissue
○ BPA is fat soluble BUT liver can quickly convert to water soluble form, which is excreted.
90% of humans have BPA in urine because of continuous exposure
○ Fat-soluble compounds can bioaccumulate
● Bioaccumulation=Fat-soluble substances build up in tissues of an organism over time.
● biomagnification=Higher on the food chain and able to consume the entire lifetime of toxins in
○ Tuna and swordfish are large predators high on the ocean food chain. They accumulate
and magnify mercury, PCBs, and DDT. ● Dichlorodiphenyltrichloroethane (DDT)
○ Half life = decades
○ First synthesized 1874; banned in USA 1972; banned by most other countries in 1970s
and 1980s, however, still used in countries around the world
○ Used extensively during WWII to fight malaria, which is spread by mosquitoes
○ Nobel Prize in Physiology or Medicine Paul Hermann Müller, 1948 – for discovery of
○ LD50 ~ 100 mg/kg oral dose for rats
○ Found in soil and water
○ Carcinogen, developmental & reproductive toxicity
○ Hydrophobic, bioaccumulated in fat tissue
○ Insecticide used widely from 1950-1980 ¤ Environmental Impact of DDT’s use was
documented by Rachel Carson’s book “Silent Spring” in 1962
● Polychlorinated biphenyls (PCBs)
○ Half life = decades
○ First synthesized in laboratory in 1881, used widely in 1930s – 1960s; banned in 1970s
○ The toxicity of PCBs reported in 1930s and 1940s; manufacturing of PCBs peaked in
○ Used by electrical industry, airline industry as coolant and hydraulic fluid; also used in
plastics industry, flame retardant
○ LD50 ~ 1000 mg/kg oral dose for rats
○ Found in soil, water, and atmosphere
○ Carcinogen, developmental & reproductive toxicity, neurotoxin
○ Hydrophobic, bioaccumulates in fat tissue
○ Pollutant of Great Lakes, Puget Sound, Hudson River Watershed, Indiana, New York
○ Many of PCBs manufactured by Boeing and GE
○ hydrophobic molecule and will bind to the hydrophobic parts of biomolecules like DNA
● i. Half life of a substance, if you know that half-life of a substance you should be able to calculate
how much of the substance remains in the environment after a particular amount of time (e.g., if
you know that the half-life of a substance is 10 hours and if you start with 100 grams, you should
be able to calculate how much will remain after 100 hours).
○ half-life=time required for the quantity to fall to half its value
● j. PCBs in orcas in Puget Sound
● k. Determining toxicity, epidemiology and toxicology.
○ epidemiology→ Look for health problem in a specific population and work backwards for
cause or look at group with exposure and identify common health problems
○ Toxicologist – scientists who study specific properties of potential toxin and how it affects
cells or tissue.
○ ii. In-vivo=“in the body” ; in lab animals
○ in-vitro= “in glass”; test cells in Petri dish
○ Toxin can be affected by HOST factors like age, genetics, other health problems.
○ Toxicity impacted by variables: genetics, age, general health status
■ Individual factors – Some toxins are more of a problem in the very young or the
very old, or those who are ill. Genetic factors may make a person more or less
vulnerable to the toxin.
■ Exposure – Whether the toxin is inhaled, ingested, or contacts the skin makes a
difference in toxicity. ■ Frequency of exposure also matters.
○ LD50 amount of substance that when given to test animals all at once causes 50%
of the animals to die.
○ LD refers to “lethal dose” and is usually tested on small mammals because they have
similar physiology to humans.
○ Toxicologists use LD50 to determine acute toxicity
○ LD50 typically given in milligrams of material per kilogram of body weight
○ be able to read a graph that shows LD-50.
● Know how endocrine disruptors cause problems in an animal, what do they target? Know about
bisphenyl A (BPA).
○ Endocrine disruptors mimic a hormone or prevent a hormone from having an effect.
■ They can have one set of effects at a low dose and no effect or different effects
at higher doses
● How hormones work:
○ Steroid hormone enters cells and binds to receptor→ Hormone receptor complex binds to
DNA in cell nucleus→ Binding activates gene which directs protein production→ New
protein made→ Protein changes cellular activity H
● Additive effects=other chemicals may increase the effect of the toxin.
● antagonistic effects=Other chemicals reduce or cancel the toxin’s effects.
● synergistic effects=Chemicals increase the effects of the toxin, even beyond expectations.
● If you are given several toxins and shown data about the toxins (e.g., LD- 50, half-life, water
soluble or fat soluble) you should be able to determine which toxin is most toxic and which is least
toxic to humans.
Week 4 January 30, 2017
● a. Population ecology⇒ a branch of biology that deals with the number of individuals of a
particular species found in an area and how and why those numbers increase or decrease over
● b. Know the 10 most populated countries on Earth
○ China, India, USA, Indonesia, Brazil, Pakistan, Nigeria, Russia, Bangladesh, Japan
● c. What type of animals do humans consume, how much of each?
● d. Exponential population growth→ the larger the population gets the faster it grows
○ i. Understand the graph that shows number of bacteria versus time→ exponential growth
■ 1. Doubling time
■ 2. 2^n=population of bacteria
● n=number of times the bacteria have doubled in size, occurs every 30
● In 24 hours the bacteria would double 48 times (n=48)
● Therefore, the population of bacteria after 24 hours of growth is = 281,
● e. Trends in human population growth
○ i.About 15,000 to 10,0000 years ago the world population is estimated to have stabilized
at 5,000,000 people who were Hunter-gatherers
○ ii. Agriculture revolution, what did it do for human population? → population growth ■ As food production increased populations increase, demands on the environment
increase; “overlaying” and “foundling” (infanticide) were common practices of
limiting family size
■ Then about 10,000 to 8,000 years ago, humans changed from nomadic lifestyle
to agricultural lifestyle, which allows for large families
○ iv. Industrial revolution, what did it do for human population?
○ v. Know the timeline for stone age, bronze age, iron age, middle age and modern times
■ Stone age (9000-3000 BCE, Agricultural revolution→ 10000-8000 BCE), Bronze
Age (3000-2000 BCE), Iron Age (2000 BCE - 0 ), Middle Ages (500-1500 AD),
Modern times ~present
■ Dramatic growth occurred twice in history-10,000 years ago with the agricultural
revolution and throughout the Industrial Revolution up until today. Changes in
sanitation, health care, nutrition, etc, led to increase life expectancy, decreased
infant mortality→ populations soared
○ vi. What was the Black Death, what was the significance in terms of population of
humans on Earth?
■ Bubonic plague (1347-1351) est. that it may have reduced the world’s population
from 500 million to 400 million
● f. How and what did the Chinese government institute in order to control population growth in
○ In late 1970s, China experienced population momentum. Even with 2 children per couple,
the #s were beyond what could be managed. In 1979, China instituted a mandatory
policy that there could only be one child per family without loss of government benefits
and a very high fine. The policy was promoted by promising improved quality of life for all.
● g. Human Population Density
○ i. Are humans evenly distributed over Earth’s surface? → NO
■ Japan, China, Bangladesh, have very dense populations
○ ii. Where do humans prefer to live (e.g., cities, freshwater, coasts, etc.)
■ The most densely populated areas in the world tend to be in coastal areas or
close to major waterways. About 90% of the people on Earth live on 10% of the
surface area, and most are north of the equator.
○ iii. Where are the most densely populated countries on Earth?
■ Japan, Bangladesh (#1), India, China.
○ iv. How much space does 7-billion people take up?
■ 7,000,000,000 x .292 m^2 = 2,000,000,000 m^2 = 2,000 km^2
■ Earth’s total land area excluding Antarctica=140,000,000 km^2
■ Therefore, population density of humans on Earth=50 people/km^2
● This number is misleading (too low) considering that 50% of Earth’s total
land area is uninha