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Review
City Council Sewage Vote
Last night the Fremont City Council, by a 4-to-1 vote, approved an upgrade of the town’s sewage
treatment facility. The treatment plant, which currently discharges one million gallons of
treated wastewater into the Fremont River daily, will be upgraded from primary to secondary
treatment next year. Councilperson Ramos noted that the upgrade was needed to protect the
water quality of the Fremont River. A local environmental scientist, Dr. Goodwin, advised the
council members that sewage treatment plants may solve a water quality problem, but they
create a solid-waste problem.
1. Identify ONE component of the sewage that is targeted for removal by primary treatment
and ONE component of sewage that is targeted for removal by secondary treatment.
Primary treatment: Large solid materials (Rocks, gravel, sand, solid human waste, twigs, cans
etc.) and (FOG fats, oils and greases)
Secondary treatment: Dissolved/suspended organic material (human waste, soaps, detergents,
food, pathogens like E. Coli and Coliform) and (phosphates and nitrates)
2. For EACH of the pollutants that you identified in part (a), describe now the pollutant is
removed in the treatment process.
All large solid materials use a physical process like grid filtration, screening, filters etc.
Sand, grit and fecal material use a settling tank to allow it to settle out
FOGs float and can be skimmed off the top
Any dissolved organic compounds can be consumed by aerobic bacteria
Pathogen killed with chlorine, ozone or UV.
Nitrates/ammonia use denitrifying anaerobic bacteria
3. Explain how sewage treatment plants create the solid waste problem that Dr. Goodwin
mentioned in the article.
Solid particulates left over after primary and secondary treatment now pose a solid waste
issue that must be disposed of elsewhere, usually in landfills.
4. Two common methods of disposing of solid waste from sewage treatment plants are
transporting it to a landfill or spreading it onto agricultural lands. Describe an environmental
problem associated with EACH of these methods.
Landfill problems: Takes up room in existing landfills and may result in the expansion or
development of new landfills. Potential contamination of groundwater from leachate.
Agricultural problems: Human and animal health problems with bacterial contamination on
food. Field runoff of human waste can contaminate surface water and lead to cultural
eutrophication.
5. The final step in sewage treatment is disinfection. Identify ONE pollutant that is targeted
during disinfection and identify ONE commonly used method of disinfection.
Any pathogens like E. Coli bacteria, Coliform bacteria, Giardia, Cholera, and Viruses.
Use chlorine, ozone, or UV.
6. Identify ONE United States Federal Law that requires monitoring the quality of the treated
sewage that is discharges into the Fremont River.
Clean Water Act or Safe Water Drinking Act
Multiple dams have been erected along the Colorado River. Identify TWO benefits other than
agriculture and recreation that people derive from that system of dams.
Hydroelectric power/affordable (inexpensive) electricity
Flood control
Storage of water for domestic/nonagricultural use; municipal water supply (must specify a
nonagricultural use)
Discuss TWO potential environmental consequences of damming a major river.
Habitat alteration; displacement or death of native species (e.g., fish, plants, birds)
Population decline of migratory fish (salmon, etc.) or disruption of fish migrations
Risk of flood from catastrophic failure of dam
Sedimentation behind dam
Downstream ecosystems deprived of sediments, nutrients, or water
Reduction of available water because of increased evaporative loss
Describe TWO conservation strategies for reducing agricultural water consumption.
Use drip irrigation
Choose crops that do not require irrigation in that climate
Breed/select/develop crops for more efficient water use or drought tolerance
Irrigate when evaporative loss is lower (e.g., at night)
Level fields to improve delivery efficiency
Identify TWO possible environmental consequences of climate change on the hydrology of the
Colorado River system.More and stronger storms/Increased sedimentation flooding and runoff
Warmer temperatures: Increased evaporation/bodies of water and soil. Reduced snow pack.
Increased precipitation: Increased surface water or groundwater inputs/Increased
sedimentation in bodies of water (opposite for decreased precipitation)
Shown below is a diagram that
indicates the sites where the
students collected water samples
(labeled A through D, upstream to
downstream) and a table of the
results of the students’ water tests.
Assess the likelihood that animal
waste is contaminating the water.
Discuss the scientific basis of your
assessment.
Yes animal waste is present. Animal
waste is composed of organic
material which must be broken
down by aerobic bacteria. Activity
by aerobic bacteria increase the
BOD (biological oxygen demand)
and therefor lowers the dissolved
oxygen in the water column as seen
between samples A and B.
Biological waste contains phosphates and nitrates. The increase in the concentrations of each
of these from sample A to B shown a possible contamination from animal waste.
Describe a sequence of ecological changes that might result from the discharge of animal waste
into a body of water.
The animal waste would increase the stream fertility by introducing phosphates and nitrates
causing an algal bloom. The algae will begin to die off and be decomposed reducing dissolved
oxygen. This decrease in dissolved oxygen will result in the loss of sensitive indicator species
like trout and larval forms of organisms.
Coral reefs are produced when corals
acquire calcium ions (Ca2+) and carbonate
ions (CO32-) from seawater and deposit
solid CaCO3 to form their exoskeletons.
Scientists are concerned that relatively
rapid decreases in ocean water pH will
hinder the deposition of CaCO3. The
graph above shows the amount of CO2
dissolved in ocean water and ocean water
pH (shown in parentheses) since 1850 and
the predicted changes through 2100.
Explain how an increase in the amount of dissolved CO2 in ocean water results in a decrease in
the pH of ocean water. When carbon dioxide dissolves in the ocean, it forms an carbonic acid
(H2CO3) which lowers the pH.
Explain why the movement of carbon into the ocean has increasing since 1850.
The concentration of carbon or carbon dioxide in the atmosphere has increased based on the
burning of fossil fuels. The ocean acts as a carbon sink and the excess carbon dioxide released
diffuses into the oceans increasing concentration.
In order to model the effects of ocean acidification on coral reefs, some simplifying assumptions
can be made. Use the assumptions in the table below to perform the calculations that follow.
Assume that the total global area of corals growing in reefs is 2.5 x 1011m2
Assume that corals grow only vertically and that the average vertical growth rate of corals is 3
mm/year.
Assume that the average density of CaCO3 in corals is 2 x 103 kg/m3.
Calculate the current annual global increase in volume, in m3 per year, of CaCO3 in coral reefs.
Show all steps in your calculation.
2.5 x 1011 m2 x 3 mm x
1m
= 7.5 x 108 m3/year
year
1000 mm
Calculate the current annual global increase in mass, in kg, of CaCO3 in coral reefs. Show all
steps in your calculation.
7.5 x 108 m3 x 2 x 103 kg = 1.5 x 1012 kg/year
year
1 m3
Because of ocean acidification, it is expected that in 2050 the mass of CaCO3 deposited annually
in coral reefs will be 20 percent less than is deposited currently. Calculate how much less CaCO3,
in kg, is expected to be deposited in 2050 than would be deposited if ocean water pH were to
remain at its current value.
0.2 x 1.5 x 1012 kg = 3 x 1011 kg
Identify and describe one likely negative environmental impact of the loss of coral reefs.
Habitat loss/Elimination of a food source for marine life, breeding grounds for fish and niches
Loss of biodiversity/loss of carbon sink/loss of coastal protection (include a description)
identify one environmental problem (other than one due to ocean acidification or loss of coral
reefs) that affects marine ecosystems on a global scale.
Overfishing
Destructive fishing practices (e.g., bottom trawling, drift netting)
Increased ocean temperatures
Introduction of invasive species
Nutrient pollution/Eutrophication
Hypoxia/Dead zones
Garbage/plastic debris (e.g., Great Pacific Garbage Patch)
Oil spills/Off-shore oil drilling
Mercury pollution
Identify one international regulation or United States federal law that applies to the harvesting
of marine food resources and explain how that regulation or law helps to manage marine
species.
ESA-Prohibits the harm or harvesting of endangered species including marine. Protects
habitats
Marine Mammal protection act-Protection and conservation of marine mammals
Cities-prevents trade of threatened or endangered species including marine
U.S. Whale Conservation and Protection act-Prohibits the harvesting of whales in U.S. waters.
The oceans of the world are often referred to as commons. Give an example of one other such
commons, explain how human activities affect that commons, and suggest one practical method
for managing that commons.
Atmosphere, Aquifers, National forests, Antarctica, any public resource.
Education to the public-like forests fire prevention, eutrophication of lakes.
Regulations or laws-like reducing phosphates and nitrates in detergents to stop eutrophication
Choose any ONE of the three pollutants mentioned above and respond to each of the following.
Describe one specific source, other than the local chemical plants, for the toxic pollutant you
choose.
PCB/Most electronics, Pesticides, Wood treatments, Paint, Plastic, Waste oil, Roofing materials
Mercury/Coal burning, mining, Thermometers, Compact fluorescent light bulbs, Dental work
Lead/Paint, Water pipes, Lead glaze on ceramics, Gasoline additives, Lead bullets and shot,
Batteries, Electronics, Mine waste containing lead, Smelting
Describe how the pollutant you chose enters the human body and one specific effect it can have
on human health
PCBs/Ingesting seafood contaminated with PCBs, Absorption through skin, Drinking
contaminated water, Inhaling dust contaminated with PCBs
Mercury/Ingesting seafood contaminated with mercury, Ingesting food or water contaminated
by soil, mine waste or particulates containing mercury, Inhaling mercury vapors (from broken
thermometers, barometers, compact fluorescent light bulbs, etc.) Absorption through skin,
Medical and dental procedures
Lead/Ingesting food or water from ceramic tableware produced with lead-containing glazes,
Ingesting food or water contaminated by soil, mine waste, particulates or plumbing containing
lead, Ingesting lead-based paint, Inhaling dust or vapors contaminated with lead
Health effects (same for all 3): Birth defects, Nervous system damage, Brain damage, Learning
disabilities, Mental retardation, Paralysis, Attention deficit disorder
Described TWO specific steps, other than an outright ban, that a city or nation can take to
reduce the threat posed by this pollutant.
Used for all 3 just change chemical:
Educate people about how to avoid PCBs, Substitute safer alternatives for PCBs, Replace
products that contain PCBs with different products, Collect and safely dispose of products
containing PCBs, Phytoremediation of contaminated areas, Treat water supplies to remove
PCBs, Restrict fishing for species known to have high PCB concentrations
Mercury only reduce coal use
Lead only remove old lead paint from buildings and replace with non lead based paints
Is the Seafood We Eat Safe?
Give reason why it is correct in asserting that
children are particularly susceptible to toxic
pollutants.
Poisonous mercury is on our dinner
plates everywhere – in sea bass served in fancy
Children take in more water, food and air
restaurants, in tuna casserole ladled out at
per unit of body weight than adults,
home. Most of the time it is harmless, but eat
Children often put dirty objects or hands in
enough and it can damage the nervous system,
their mouths, Children have less developed
especially the brain, and too much in pregnant
immune systems, The liver of a child does
and breast feeding women can hurt their
not metabolize pollutants as efficiently as
babies – adversely affecting children’s
the liver of an adult.
intelligence, coordination, and memory. But
how much is too much? Are adults at risk as
well?
On the basis of the article above, indicate one human activity that releases mercury into the
environment. Describe how mercury is transported form that source and enters aquatic
systems, often hundreds of miles away.
Humans release mercury into the environment through the burning of coal. The unburned
coal, soot and gases, enter the atmosphere from giant smokestacks. Once in the air the
mercury is transported hundred of miles in air currents (wind) and is deposited into aquatic
systems by precipitation. Once in the water it becomes incorporated into the food chain and
bioaccumulates and biomagnifies.
Describe TWO ways that the amount of mercury released into the environment form the source
in part (a) could be reduced.
Burn higher rank coal to generate more BTUs with less coal burning. Use a different type of
fossil fuel, like natural gas that has low to no mercury. Switch to renewables like solar.
An important contributor to global climate change is the release of carbon dioxide form the
rapidly increasing number of coal-burning power plants in China. Assume that the coal burned
at these plants to provide the power to manufacture a single MP3 player releases 40 kg of
carbon dioxide and that costs $0.75 to capture 1 kg of carbon dioxide and keep it from entering
the atmosphere. Determine the cost, in dollars, to capture the total amount of carbon dioxide
released from manufacturing one MP3 player.
40kg CO2 x $0.75 = $30
1 kg CO2
Coal-burning power plants also release other pollutants, including nitrogen oxides (NOx), sulfur
oxides (SOx), and particulates. Select one of these pollutants and identify one technology that
can be used to remove it from the waste stream of coal-burning power plants.
All three Coal gasification (is the process of producing syngas)
For particulates/Scrubber, Filters and Electrostatic precipitator
Discuss TWO reasons why a multinational company would choose to build a manufacturing
facility in India and/or China rather than in the United States or Europe.
Less stringent environmental regulations, Less expensive labor (Large populations of workers
willing to work for lower wages), Lower health-care costs for workers, Less expensive property
Explain why there are greater health risks associated with eating large predatory fish, such as
tuna and sea bass, than from eating small non-predatory fish.
Bioaccumulation and biomagnification