Environmental Study Guide: Pages 229-251
Created by Samyuth Subramanian
5.3.3: Evaluate the costs and benefits to society of the World Health Organization’s ban
on the use of the pesticide DDT.
Definitions:
DDT — (dichloro-diphenyl-trichloroethane) is a synthetic pesticide with a controversial
history. Commercial DDT is actually a mixture of several closely related compounds,
including DDE and DDD (which happen to be the breakdown products of DDT in the
environment.) It is classified as a POP (persistent organic pollutant). DDT is extremely
hydrophobic and is strongly absorbed by soils and lipids. This makes it easy to build up
in the fatty tissue of animals and is a good example for biomagnification and
bioaccumulation in conjunction with an example (i.e. American Bald Eagle).
Biomagnification — is the process by which the concentration of a chemical increases at
each tropic level, and a consequence is that top predators have concentrations of
chemicals million times higher than water or primary producers.
Bioaccumulation — is the retention or build-up of non-biodegradable or slowly
biodegradable chemicals in the body. This produces a body-burden of the substance.
Costs: Mainly increased rates of Malaria
In the past DDT has been used to control the spread of lice and mosquitoes, and this use
has continued to the present. Because of its ability to kill pests, DDT was used
extensively as an insecticide in farming. DDT has especially been used to combat the
spread of Malaria; however, countries are now trying to phase its use out. DDT is still
used as an insecticide in countries like India and North Korea (in 2006, only 13 countries
were still using DDT). By the 1990s, most developed countries had phased out the use of
DDT completely, while other countries have limited its use to indoor residual spraying
(IRS — no not the tax agency).
Benefits: Resurgence of endangered bird populations, better human health
Studies into the effect of DDT on the health of humans have revealed that DDT is bad for
humans. Studies have found that people exposed to DDT have an increased incidence of
asthma, diabetes, liver, breast, and pancreatic cancer, early pregnancy loss, premature
birth, low birth weight, and infertility. The most researched and accepted risk is the
increased incidence of asthma and other lung disorders.
From the time of its creation in World War II onwards, up to 1.8 million tons have been
produced globally since the 1940s. The ban on its use started with the introduction of the
book Silent Spring by Rachel Carson. This book marked a change in attitude towards the
environment, one that sparked more environmental awareness.
Eutrophication — refers to the nutrient enrichment of streams, ponds and groundwater. It
is caused when increased levels of nitrogen or phosphorous (but more so phosphorous)
are carried into water bodies. It can cause algal blooms, oxygen starvation and eventually
the decline of biodiversity in aquatic ecosystems.
5.4.1: Outline the processes of eutrophication.
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Increase in nitrates and phosphates in water
Rapid growth of algae in response to increased nutrient availability
Light blocked from submerged aquatic plants
Accumulation of dead organic matter
Increased activity of decomposers
Increased removal of oxygen by decomposers
Reduced oxygen kills fish and other organisms (anoxia — oxygen starvation)
5.4.2: Evaluate the impacts of eutrophication
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High concentrations of Nitrogen cause undesirable effects (some of which
mentioned below)
Loss of fertilizer (with nitrogen and phosphorous compounds causing
eutrophication) via run-off is an economic loss to the farmer
High nitrate concentrations in drinking water may affect human health
Increased biomass of phytoplankton (i.e. blooms)
Toxic or inedible phytoplankton species (water quality)
Changes in macrophyte species composition and biomass
Decreases in water transparency (increased turbidity)
Color, smell, and water treatment problems
Dissolved oxygen depletion
Increased incidences of fish death
Loss of desirable fish species
Reductions in harvestable fish and shellfish
Decreases in perceived aesthetic value of the water body (case study: Lake Erie)
Case Study: Lake Erie
Lake Erie during the 1960s underwent rapid anthropogenic eutrophication. Much of
our understanding of eutrophication arose because of this incident. The University of
Manitoba set up numerous experimental lakes (called Experimental Lakes Area) in
1968 to investigate. They found out, through numerous controlled experiments where
they dumped different chemicals (like nitrogen and phosphorous) into numerous
controlled lakes, that eutrophication was primarily caused by phosphorous
compounds dumped into the St. Lawrence basin. They successfully designed a
phosphate control program through legislation to clean up the basin area.
Case Study: England and Wales — the gist of it is that the tap water is contaminated
by nitrates that have seeped into aquifers over 40 years.
Case Study: Kunming City, China — the gist of it is that the lake (Dianchi Lake) near
the city was used to drain sewage and factory byproducts causing it to undergo
eutrophication.
5.4.3: Describe and evaluate pollution management strategies with respect to
eutrophication.
There are three main ways to deal with eutrophication:
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Altering the human activities that produce pollution by using alternative types of
fertilizer, detergent, and so on. This strategy relies on the companies and the
people involved, which means often times a vested interest. This means that
strategies aimed at altering the status quo are frowned upon and more often
ignored despite their greater technical feasibility and lesser cost.
Regulating and reducing pollutants at the point of emission (e.g. sewage
treatment plants that remove nitrates and phosphates from the waste via
stripping). Stripping is the most popular example for this method, and is more
technically feasible and cost-effective then clean-up. However, this method does
not easily make use of stripped nutrients whereas clean-up has the potential to do
so.
Clean-up and restoration of polluted waters by pumping mud from eutrophic
lakes. This option generally has the greatest cost and least technical feasibility,
but comes with the chance to use the byproducts.
5.5.1: Outline the types of solid domestic waste
The main types are usually classified as organics, paper/board, glass, metals, plastics,
textiles, and then other. Further breakdown is provided below:
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f.
g.
h.
i.
j.
k.
l.
Garden waste (20%)
Kitchen Waste (17%)
General Household Sweepings (9%)
Glass (7%)
Wood (5%)
Wood and Furniture (5%)
Scrap Metal/ White Goods (5%)
Soil (3%)
Textiles (3%)
Metal Packaging (3%)
Disposable Nappies (2%)
Paper and Board (1%)
5.5.2: Describe and evaluate pollution management strategies for solid domestic
(municipal) waste.
a. Waste can be reduced by producers thinking more about the lifespan of
products and reducing packaging and consumers considering packaging
and lifespan when buying goods.
b. Goods can be re-used to extend their life-span by bring-back schemes (ex:
milk bottles), refurbished/reconditioned goods to extend usefulness, used
goods put to another use, and charity shops passing on goods to new
owners.
c. Also value can be recovered by recycling goods, composting goods for
fertilizer, and incinerating waste to collect electricity and heat.
d. And lastly disposing of waste in landfill sites, into a hole where it will
make natural or artificial hills.
A landfill is a location with a hole in the ground natural or human made that is isolated by
physical barriers, that waste can be dumped in and left to rot without disturbing the
population. Many landfills are monitored for leaching and are often covered with dirt and
grass to give the appearance of a hill.
Advantages of landfills
 They are cheap methods of disposal
 Does not require much maintenance
Disadvantages of landfills
 Increased risk of health problems, such as heart failure and birth
defects for the area around the landfill.
 Need to be near sources of water
 Give off dangerous gasses like methane
 May contaminate ground or nearby water ways through barriers
 Running out of space.
 Not in my backyard
Ways is incineration a better option than landfills
 Much less maintenance of waste
 Less chance of polluting water sources
 Uses less space
 Quicker process of removal of waste
 Ash is easier to deal with (product of incineration.
Disadvantages of incineration
 Massive amounts of air pollution, which can lead to lung problems
and acid rain
 Volume of traffic generated is increased, leading to air pollution
 Ash is often toxic and still led back to a landfill.
 Building incinerator requires a lot of capital and demonstrated
need.
5.6.1: Outline the overall structure and composition of the atmosphere.
The atmosphere is a mixture of gases liquids and solids. Atmospheric gases are held close
to the Earth by gravity. The spatial and temporal variations in atmospheric composition
produce weather and climate. The composition of the atmosphere are ozone from 1050km, nitrogen from 100-200km, oxygen from 200-1100km, helium from 1100 to
3500km, and hydrogen above 3500km. The atmosphere is also broken up into specific
layers. From the bottom up, these are the troposphere, stratosphere, mesosphere, and
thermosphere (weather takes place in the troposphere).
5.6.2: Describe the role of ozone in the absorption of UV radiation
Ozone occurs because oxygen rising up from the top of the troposphere reacts under the
influence of sunlight to form ozone. Most ozone is created over the equator and between
the tropics because this is where solar radiation is strongest. However, winds with the
stratosphere transport the ozone towards the Polar Regions where it tends to concentrate.
Ozone has the vital role of absorbing ultraviolet radiation. This makes Ozone technically
a greenhouse gas. Ozone is constantly being produced and destroyed in the stratosphere
by in a natural dynamic balance produced by sunlight and destroyed by nitrogen oxides.
The UV radiation breaks down oxygen molecules into two single oxygen atoms, which
combine with oxygen molecules to from ozone. This process shields the surface of the
planet from harmful radiation.
5.6.3: Explain the interaction between ozone and halogenated organic gases
Halogenated organic gases, like chlorofluorocarbons react and destroy the ozone layer.
These halogenated organic gases are a result of industrial process, which is human
activity. These gases are catalysts for reactions that destroy ozone molecules, and thus
greatly increase the rate of ozone depletion.