POPULATION AND POLLUTION
The Spread of Shakespeare’s Starlings
The European Starling has become an abundant and destructive pest in North America.
Multiple factors may limit population growth. As a population’s density increases, factors such as limited food supply and increased disease or predation may increase the death rate, decrease the birth rate, or both. The human population has been growing almost exponentially for centuries, standing now at about 6.4 billion
The baby boom was in the 1950s when the American birthrate skyrocketed. When the so-called baby boomers were in their 20s, they were young and vibrant, and they added to American productivity. Today, however, the boomers are aging. Their children worry that elderly boomers will drain resources, not to mention national attention, from younger adults.
Human Population Growth
The world population increases the equivalent of a medium-sized city (200,000) every day and the equivalent of a country the size of Germany (80 million) every year. Most of the growth is coming from less-developed countries.
Right now, there are about 6 billion people on the planet, but in the next 100 years, there will be about 8-11 billion.All populations need nutrients, space, water, and energy.
This means that in about 50 years, the world will need double the amount of food, jobs, water, energy, and so on to maintain the same standard of living. Right now, half of our world’s population do not have electricity or indoor water and cannot read even enough to sign their name.
We are adding a billion more people to the planet much faster than we used to. We got our first billion in 1800; the second billion arrived in 1930; the third billion in 1960; and today there are 6 billion. Only if the growth rate continues to decline can there be zero population growth when births equal deathsand the population size remains steady.
The More-Developed Versus Less-Developed Countries
The MDCs of North America, Canada, England, and Europe, have a population growth under control and the people enjoy a good standard of living. The LDCs of South America (Argentina, Brazil, Chile), Africa, and Asia, have population growth out of control and the majority of people live in poverty.
The term “third-world countries”is an old term used to mean the less-developed countries. This term was introduced by those who thought of the United States and Europe as the first world and the former USSR as the second world.
The MDCs doubled their populations between 1850 and 1950 because of a decline in the death rate and modern medicines. The populations of a few of the MDCs, Italy, Denmark, Hungary, Sweden are actually decreasing in size. In contrast, there is no leveling off and no end in sight to U.S. population growth.
Although the death rate began to decline steeply in the LDCs following World War II with the importation of modern medicine from the MDCs, the birthrate remained high.
Comparing Age Structure
One way of characterizing population is by age groups. If there are more young women entering the reproductive years than there are older women leaving them, there will still be an increase in population. Most LDCs have a large proportion of young women under the age of 15.
Possible Solutions
1.Establish and/or strengthen family planning programs.
2.Use social progress to reduce the desire for large families by providing education, raising the status of women, and reducing child mortality rate.
3.Delay the onset of childbearing by five years and wider spacing of births.
The Human Population and Pollution
Intact ecosystems naturally prevent soil erosion, dispose of environmental wastes, provide fresh water, regulate climate. But as the human population increases in size, more ecosystems are impacted by humans. Ecosystems are no longer able to process and rid the biosphere of wastes and leads to problems for all living things, and also problems in the air, in the water, and on land.
Air pollutants in particular are involved in causing major environmental effects, including global warming, acid rain, and ozone depletion. These terms are used on the news all the time, so I thought I’d tell you a little about what that means.
FOSSIL FUELS
Problems with the use of fossil fuels such as coal and oil and gas include the fact that they are nonrenewable, they pollute the environment when they are burned, oil and gas wells pollute the environment by emitting greenhouse gases, and they are contributing to the problem of global warming. The trend for the future is the use of hydrogen for energy.Hydrogen-based fuel cells are in use now in some cities to power vehicles, can be produced locally all over the world, and will reduce global warming and air pollution
POLLUTION
Pollution is any undesirable change in the environment that can be harmful to humans and other life, and does not normally occur.
Natural ecosystems are stable in the sense that they take care of themselves and are balanced in the interaction of the species in them. There is just enough food and energy to support the populations in them.
Human-impacted ecosystems essentially have two added parts: the country, where agriculture and animal husbandry are found, and the city, where most people live and where industry is carried on. These two systems require two major inputs: fuel energy and raw materials (e.g., metals, wood, synthetic materials). The use of these necessarily results in waste and pollution.
The Country
The country areas are where our food is grown, but it has an impact on our ecosystem.
1.Heavy use of fertilizers and pesticides contribute to water pollution, and pesticides kill off beneficial soil organisms.
2.Generous irrigation by river water will dump a heavy concentration of salt back into the river. The salt content of the Rio Grande River in the Southwest is so high that the government has built a treatment plant to remove the salt.
3.Excessive fuel consumption for water pumps and large farming machines.
4.Loss of land quality. Evaporation of excess water can leave behind excess salt, making it unsuitable for the growth of more crops.
The City
Industries increase the amount of carbon dioxide in the atmosphere. The city is dependent on the country to meet its needs. For example, each person in the city requires several acres of land from the country for food production. Unfortunately, however, as the population increases, the amount of farmland goes down when it needs to go up.
Cities currently rely mainly on coal and oil for fuel. The city wastes fuel in many ways.
- An office building with lights always on and windows that cannot be opened.
- People who drive cars long distances instead of carpooling or taking public transportation and who drive short distances instead of walking or bicycling.
- Materials are not always recycled.
Note that having an air conditioner on during a hot day is NOT an example of wasting fuel.
Burning fossil fuels causes air and water pollution. Chemical and solid wastes cause pollution, both during its production and when it is discarded. Humans themselves produce much sewage that is discharged into bodies of water, often after only minimal treatment.
The Solution
In human-impacted ecosystems, fuel combustion byproducts, sewage, fertilizers, pesticides, and solid wastes all are added to the environment in the hope that natural cycles will cleanse the ecosystem of these pollutants. However, we have exploited natural ecosystems to the extent that the environment is overloaded.
We have an ever-increasing number of people want to maintain a standard of living that requires many goods and services. But we can help this if we achieve zero population growth and if we conserve energy and raw materials. Conservation can be achieved in four ways:
- Wise use of only what is actually needed
- Recycling of iron, copper, lead, and aluminum
- Use renewable energy resources
- Development of more efficient ways to utilize all forms of energy
Some farmers have adopted organic farming methods and do not use fertilizers or pesticides. Instead, they use special planting techniques to control weeds, crop rotation to combat major pests, and the growth of legumes (a type of bean that makes nitrogen) to supply nitrogen fertility to the soil.
Some farmers use natural predators and parasites instead of pesticides to control insects. Organic farms require only about two-fifths as much fossil energy. There is one-third less soil erosion.
It is important to consider that ecosystems should be developed and managed with care so that their integral nature is preserved. This is often called “working with nature” rather than against nature.
Pollution of Oceans
Pesticides and other chemicals get into the ground and water supply, and new plants absorb them, animals eat the plants, and humans eat the plants and the animals. In that way, our bodies pick up these toxins.
The oceans are the final receptors for water pollutants carried by rivers. Waste products that are dumped into areas that drain into the ocean can also be washed back to shores. The plastic piece that holds a six-pack of cans gets tangled in birds, fishes, and marine mammals, causing their death.
Oil spills in the ocean kill plankton, fish, and shellfish, as well as birds and marine mammals. The largest tanker spill in U.S. territorial waters occurred on March 24, 1989, when the tanker Exxon Valdez struck a reef in Alaska and leaked 44 million liters of crude oil.
Cyanide Fishing and Coral Reefs Human Biology by Sylvia Mader (p. 536)
coral reefs are areas of biological abundance found in shallow, warm, tropical waters just below the surface of the water. They occur in the Caribbean and off the coast of the Southern Hemisphere continents. The great barrier reef off the coast of Australia is the largest coral reefs in the world. The chief constituents of a coral reef are stony corals, animals that exist as small polyps with a calcium carbonate exterior. Corals do not usually occur individually; rather they formed colonies derived from just one individual. When corals die off, they leave behind a hard, stony, branching limestone structure. The large number of crevices of a coral reef provides shelter for many animals, including sponges, small fish, jellyfish, and enemies, sea stars, crabs, shrimp, lobster's, turtles, see snakes, snails, octopuses, and clamps. The barracuda, wore a deal, and shark are the top predators in coral reefs.
Coral reefs are such incredibly diapers ecosystems that they are often referred to as the rain forests of this sea. They are home to thousands of known species, with perhaps millions more are yet to be documented. Coral reef degradation is a worldwide problem that involves overfishing for the food and aquarium trades, careless tourist divers, impacts from boat anchors and propellers, oil spills, nutrient pollution, global climate change, and an increase in coral diseases. It has been estimated that 58% of all coral reefs are being harmed by human activities. Even so, many aquarium hobbyists enjoy collecting and caring for the beautiful fish, starfish, CNN and knees, and other organisms that called the reefs home.
One of the most damaging methods of collecting aquarium fish from coral reefs is known as cyanide fishing. Cyanide is a poison that interferes with the mitochondria within the cells of the fish and it shuts down respiration. Reef fish can be challenging for divers to capture with hand-held nets alone, since they are able to seek refuge in hard to reach Nokes and crannies. However, spewing a cyanide solution over the fish stuns them and makes them much easier to catch. Unfortunately, cyanide dosing in open water is a tricky proposition. Many fish die immediately, and even more died later from aftereffects of the poison. To make matters worse, the coral itself, which takes thousands of years to grow and form a reef, can die from the cyanide. Even the diapers can inadvertently poison themselves.
The United States imports almost half of all marine aquarium organisms. Approximately two thirds of them come from the Philippines, where cyanide fishing began, and Indonesia, throughout which the practice has spread. Even though cyanide fishing is officially illegal, many of the people in this region live in poverty. As a result, numerous individuals feel that they must assign a lower priority to protection of the coral reefs in the effort to earn a living.
There is hope that cyanide fishing may become a less popular way of obtaining organisms for the aquarium trade, as hobbyists and retailers become better educated about the harmful effects of this practice. The Marine Aquarium Council is a nonprofit, international organization that certifies marine organisms as having been harvested using environmentally responsible methods. However, some scientists contend that removing fish by any means may be detrimental to the reef community, since some of the most popular aquarium fish are herbivores who keep the plants of the reefs from growing too much and overwhelming the coral.
- Do you think that marine aquarium hobbyists who opt to buy only Marine Aquarium Council-certified fish are making a responsible choice? Or, do you think that stricter measures are necessary?
- Should the immediate needs of humans take precedence over preserving coral reefs? Can you think of alternatives to cyanide fishing that would help people who live near coral reefs to make a living?
- At this time, some nations, such as the United States and Australia, have designated small “no take” zones within their reef systems, where harvesting of reef organisms is sure to leave prohibited. Do you think that this is a useful step toward coral reef preservation? Can you think of any disadvantages of this approach?
Pesticide: An Asset and a LiabilityHuman Biology by Sylvia Mader (p.421)
A pesticide is any one of 55,000 chemical products used to kill insects, plants, fungi, or rodents that interfere with human activities. Increasingly, we have discovered that pesticides are harmful to both the environment and humans. The effect of pesticides on union system is a new area of concern; no testing except for skin sensitization has thus far been required before pesticide products are put on the market. Contact or respiratory allergic responses are among the most immediately obvious toxic effects of pesticides. But pesticides can also cause suppression of the immune system, leading to increased susceptibility to infection or tumor development. Lymphocyte impairment was found following the worst industrial accident in the world, which took place in India in 1984. Nerve gas used to produce an insecticide was released into the air; 3700 people were killed, and 30,000 were injured. Vietnam veterans claimed a variety of health effects due to contact with an herbicide called Agent Orange that was used as a defoliant (to strip the leaves off plants to clear the path for the troops) during the Vietnam War. The Environmental Protection Agency says that pesticide residues on food possibly cause suppression of the immune system, disorders of the nervous system, birth defects, and cancer. The immune, nervous, and endocrine systems communicate with one another by way of hormones, and what affects one system can affect the other. In men, testicular atrophy, low sperm counts, and abnormal sperm may be due to the ability of pesticides to mimic the effects of estrogen, a female sex hormone.
The argument for using pesticides at first seems attractive. Pesticides are meant to kill off disease causing agents, increase crop yields, and work quickly with minimal risk. But over time, it has been found that pesticides do not meet these claims. Instead, has become resistant to pesticides, which kill off their natural enemies in addition to the past. Then the pest population explodes. For example, at first ET did a marvelous job of killing off the mosquitoes that carry malaria; now malaria is as big a problem as ever. In the meantime, DDT has accumulated in the tissues of wildlife and humans, causing harmful effects. The problem was made obvious when birds of prey became unable to reproduce due to weak eggshells. The use of DDT is now banned in the United States.
There are alternatives to the use of pesticides. Integrated pest management uses a diversified environment, mechanical and physical means, natural enemies, disruption of reproduction, and resistant plants to control rather than eradicate pest populations. Chemicals are used only as a last resort. Maintaining hedgerows, weedy patches, and search in trees can provide diverse habitats and food for predators and parasites that help control past. The use of strip farming and crop rotation by farmers denies past a continuous food source.