Food is essential for all animals. We all know that food is dependent
on healthy soil, air, and water; few know how food is dependent on the presence
of food for all life (this is known as the food chain).
"Every day in the U.S. four square miles of our nation's prime
farmlands are shifted to uses other than agriculture. The thief is
--National Agricultural Lands Study, 1979
As you can see from this previous question, soil
is eroding away faster than it can be formed! Erosion occurs when
water cannot soak into the soil, such as on slopes or paved roads.
Topsoil is necessary because it is the rich medium in which our food is
grown, not to mention all other plants. Without the rich topsoil,
nothing can grow well. Land needs to be managed so soil is protected
and can hold water--one solution is contour farming. Other major
causes of erosion of topsoil are removal of plant cover, overgrazing, poor
logging, and off-road vehicles. These lands are just becoming like
deserts--this must be stopped if we expect anything to grow in the near
future. Remember, if plants cannot grow, we will have no food or
Problem: Fertilizers and
Pesticides Don't Work Normally, plants get their essential nitrates from
nitrogen-fixing bacteria, which can be found
in nodules in the roots of legumes. However, when farmers try to
speed up this process and add artificial fertilizer into the soil, some
problems result. Fertilizers do not degrade well, and the regeneration
process leads to erosion of the soil. Instead of using fertilizer,
it is best for nitrogen to be put back into the soil by using manure or
a crop rotation involving legumes.
Contrary to common belief, PESTICIDES DO NOT WORK
effectively! Actually, PESTICIDES CAUSE A BIGGER PROBLEM!
Almost everyone knows of Darwin's laws of survival of the fittest by a
struggle through existence by means of natural selection. However,
now we are bringing in artificial selection which can lead to problems.
First of all, there are always mutants which are immune to the pesticide.
Using the pesticide kills off all of the non-resistent pests, but leaves
a few pests which are resistant to the pesticide. These immune pests
interbreed, and cause more pests--but now they are all immune to the pesticide!
As a result, farmers just spray more pesticide, which is completely ineffective.
This can lead to domination by the immune species, and forms a new breed
of species which is harder to kill. Furthermore, pesticides harm
the environment and cause other nasty effects, which hurt the organisms
in an ecosystem.
So, what can we use instead of pesticides?
Biological controls are not only natural, but they usually do not hurt
the environment as much. Some effective means of control include:
parasites and other predator species
natural biochemicals that attract, retard, or destroy pests, such as pheromones,
hormones, sterilizers, and other regulators
microorganisms such as bacteria, viruses, fungi, and protozoans
Problem: Groundwater Contamination Nitrates and pesticides can flow through cracks,
wormholes and fissures; they can be detected ten to fifteen feet below
the surface just two days after application.
Pop Quiz: The most abundant of all surface water pollutants
in the U.S. is sediment, which results in damages estimated to be $1 billion!
Sediment fills reservoirs, increases the number and strength of floods,
clogs canals, wrecks industrial equipment, raises the cost of purifying
water, etc. If freshwater is not protected, there may be a fight
between countries over freshwater resources! Please see the water
cycle for more information on this topic.
Something to think about: reload this page to see
how many more people are on this planet while you were reading this page!
Increasing Birthrates and Decreasing
Death Rates -- They Spell Trouble! Population size depends on both birthrates and death
rates. In countries where the death rate has gone down faster than
the birth rate, there is a growing population. Other parts of the
world have a more balanced population where the death rate is as high as
the birth rate. Unfortunately, as our population increases, other
species have been forced out of their homes and killed--some to the brink
In 1950, there were just 2.5 billion people.
You can see how many people there are now from the counter above!
It is expected that the population will reach 10.2 billion by 2100!
Just imagine how life would be with this many people--horrible traffic
jams, hordes of people needing homes, overcrowding schools and hospitals, not enough jobs, waiting to get to someone on the phone, and even congestion on
the Internet! Worst of all, you may think the lines at Disneyland
are long enough now, just imagine what they will be like when the population
is twice the size :-) ! Already one half of the world does not have sanitary
toilets. One out of three people do not have enough fuel to keep warm
or cook; imagine how things will be when there are even more of us!
Past experience in the ecological record shows that when a species reproduces
at a rate beyond its support for food, the food supply will soon run out
and the population will crash. Does this sound familiar to what is
happening now? How large is your family?
The average American uses 54 times more resources than the average
citizen living in a developing country. People in the developed world
spend only 14% to 30% of their income on food, while those in developing
countries need to spend 50% to 70%
Overconsumption and squandering of resources is just
as hard on the environment as overpopulation. The total degradation
on the land is equal to the population times the consumption. When
one or the other (or both) is large, the ecosystem is put in danger.
Problem: Health Threats
from Pollution and Radiation Pop Quiz:
Nowadays, cancer is a major environmental hazard.
Radiation, some chemicals, and asbestos are all carcinogenic and can alter
cells. Children, especially, are more prone to developing cancer
from these substances. Cancer takes a long time to develop and children are usually more exposed to it in their longer lifetime. Also, children
are still growing so their DNA can be subject to mutations.
Acid rain has a terrible
impact on forests and water ecosystems, along with causing human health
problems. Natural rain has a pH between 5.0 and 5.6, and rain with
a hydrogen ion content lower than this is classified as "acid rain." A
pH of just 4.7 kills the tiny plants and animals (plankton) on which fish
feed, which causes the fish to starve and die. Car exhaust is the
prime contributor to acid rain, and next comes coal-burning power plants.
Biomagnification, or the accumulation of metals
and toxins in the food chain, can become deadly. Water which is contaminated
by poisons such as DDT and pesticide can contaminate fish, shellfish, and
other items that we eat. However, as these poisons travel up the
food chain, the effects "magnify" and become larger. This exponential
growth in toxicity can be harmful to humans.
Radiation is deadly because it causes cells to mutate.
Often, lab rats exposed to high doses of radiation undergo "mutagenesis,"
which is an altering of the DNA within the cells. This is most likely
to cause cancer, leading to a premature death.
Lead poisoning is a serious threat, especially for
the poor working classes and urban city dwellers. Adults can suffer
from high blood pressure (hypertension) and heart attacks, while fetuses
can get prenatal birth defects. Children can receive irreversible
mental disabilities, retardation, and even die from eating a few chips
of leaded paint! Lead can be emitted from gasoline, coal burning,
mining, burning of trash, and manufacturing. Old lead pipes and ceramics
can also cause lead contamination. Even the burning of color comics
or wrapping paper releases lead!