Unit 5 Review Book Pt. 3 Flashcards
(25 cards)
Global Water Needs
Scientists differentiate between countries that are water-stressed and those that are water-scarce.
Countries that are water-stressed have a renewable annual water supply of about 1,000–2,000 m3 per person, but countries that are water-scarce have less than 1,000 m3 per person and lack sufficient freshwater resources to meet demand.
Currently, approximately 4 billion individuals experience severe water scarcity for at least one month a year, and 500–700 million people in 43 countries experience severe water scarcity year-round.
Many of the countries that are currently considered water-scarce are developing countries that have rapidly increasing populations—which means that their water-scarcity problems will grow over time.
Water scarcity is affected by national and regional politics, civil strife, and other issues affecting access and distribution; and lists of water-scarce countries differ by the source reporting.
However, among the countries currently experiencing the most severe water scarcity are Yemen, Libya, Jordan, Western Sahara, and Djibouti. Unfortunately, more and more countries are expected to become water-scarce by the year 2050.
Water Use in the United States
he United States is not considered water-scarce, but certain regions of the United States are considered water-stressed. Additionally, water use in the United States is out of control—we use water more quickly than it can possibly be replenished, so water scarcity is definitely in our future if we continue to use water at our present, furious rate.
The hydrologic cycle supplies the water that we use for all of our activities. Water used in our home, manufacturing, cooling equipment that generates
electricity, and irrigating croplands are a few examples. To give you a sense of water use in the United States, take a look at the chart below that shows trends in water withdrawals and population from 1950–2010.
As you see, the nation’s water use peaked in about 1980 and has been fairly steady since then. Many of the stresses making greater water use likely have risen since 1980, such as population, irrigation of crops to feed this larger population, and more industry, yet total water use has not risen. The fact that water use has leveled off despite the increase in these stresses shows that water conservation efforts and greater efficiencies in using water have had a positive effect in the last 35 years. Nonetheless, we often hear environmental news stories covering droughts, proposed emergency water relief plans, and rules about lawn watering.
What Are We Doing About Water Use?
Water is a tricky business.
It’s difficult for politicians and lawmakers to put restrictions on water use because many people think that water should be free.
After all, it falls from the sky; we can take a bucket from the lake down the street and no one will arrest us for stealing.
For the AP Environmental Science Exam, you should know about certain concepts of human water rights.
The first is the idea of riparian right. Riparian means of, on, or relating to the banks of a natural course of flowing water, and riparian right is the right of people who have legal rights to use that area.
Alternately, in prior appropriation, water rights are given to those who have historically used the water in a certain area. In other words, prior appropriation can be thought of as water squatters’ rights!
Desalinization isn’t viable economically
It has been proposed that, in order to solve current global water crises, we simply take tons of ocean water and desalinate it—this is a fairly simple process physically, but unfortunately it isn’t currently economically viable on a large scale, because it takes a great deal of energy to remove the salt through distillation or reverse osmosis.
As water becomes scarcer globally, it will be important for countries to think of ways to regulate the use of water, as estimated global water consumption is set to continue rising.
As global water crises become more common, research into the economic viability of desalination has increased.
Fishery and regulation
The term fishery is used in several ways, but it is primarily defined as the industry or occupation devoted to the catching, processing, or selling of fish, shellfish, or other aquatic animals.
In the economic sense, a fishery is the sum of all activities on a given marine resource.
Worldwide, about one billion people depend on fish as their main source of food, and about 35 million people are currently employed in the fishing industry.
Incredibly, about 172 million metric tons of fish are harvested each year.
For many years, nations were subject to what is known as the 12-mile limit —this limited each nation’s territorial waters to just 12 miles from shore.
However, in the late 1960s, the depletion of a number of offshore fisheries inspired the United Nations to host a series of international conferences to address the problems of fish scarcity.
The result of this conference was that nations were authorized to extend their limits of jurisdiction to 200 miles from shore.
Tragedy of Free Access, depletion of fish, mitigation
The depletion of marine fisheries worldwide came to be seen as a further example of the tragedy of the commons on an international scale.
A new term was coined to recognize this shift: the Tragedy of Free Access.
Today, fishermen must go farther and farther out to sea to catch fish and need to rely on more sophisticated methods for finding them.
Sonar mapping, thermal sensing, and satellite navigation are just a few of the advances that have aided fishermen as fish become scarcer and harder to locate.
Capture fisheries
Most of the fish that are harvested worldwide come from capture fisheries; they are caught in the wild and not raised in captivity for consumption.
Some of the techniques that have been developed in order to improve fishing yields are creating problems that relate to overfishing.
By-catch
By-catch
One of these problems is known as by-catch. By-catch refers to species of fish, mammals, and birds that are caught during fishing operations but are not the target fish.
Some fishing methods that result in by-catch
drift nets, which float through the water and indiscriminately catch everything in their path;
long lining, which is the use of long lines that have baited hooks and will be taken by numerous aquatic organisms;
bottom trawling, in which the ocean floor is literally scraped by heavy nets that scrape away or smash everything in their path, including corals and other delicate marine life on underwater mountains known as seamounts.
Mitigating by-catch
Some advances that have been made in the fishing industry in an attempt to mitigate the problems of by-catch are restrictions on the use of drift nets, the installation of ribbons on bait hooks that scare away birds and prevent them from being caught, and bans on bottom trawling.
The National Oceanic and Atmospheric Administration worked with fisheries that used trawling for shrimp to design an apparatus called a Turtle Excluder Device (TED).
It is located at the end of the trawling net and will eject large organisms such as sea turtles and sharks from the net while keeping most of the shrimp.
Partial solution to overfishing: aquaculture
One partial solution to the problem of overfishing is aquaculture, which is the raising of fish and other aquatic species in captivity for harvest.
In general, the fish that are raised in captivity are those with the highest economic value—for example, salmon and shrimp.
Various different methods are used in aquaculture—some fish are raised totally in captivity and then harvested, while others (like salmon) are initially hatched in captivity, but then released into the wild and captured later.
Some saltwater aquaculture is performed in shallow coastal areas, though this is generally for raising seaplants and mollusks.
Also known as fish farming
Problems with aquaculture
While aquaculture, also known as fish farming, does help to meet worldwide demands for fish, it is not a panacea for all of our fishery problems.
One concern about aquaculture is the possibility of the accidental release of farmed fish into the wild, which has the potential to introduce new diseases to ocean fish and contaminate the native gene pool.
Carp released from fish farming in Southern states are currently causing issues in the Mississippi River and the Great Lakes.
Another problem lies in the fact that many fish that are raised in captivity are carnivorous and are fed captured wild fish, which defeats the purpose of the attempt to kill fewer wild fish!
Endangered sea animals: dolphins
Most of the public outcry about the endangered animals of the sea has centered on two groups: dolphins and whales.
Dolphins are a high-profile by-catch, and as you may have noticed, many cans of tuna now advertise as having been caught using “dolphin safe” nets.
The slogan “Save the Dolphins” has been frequently employed by international marine conservation groups.
However, that slogan is impossible to obey unless humans first work to save the natural habitat of these creatures.
Endangered sea animals: whaling
The International Whaling Commission (1974) regulates whaling.
Recent policies implemented by the IWC allow the capture of a certain number of whales annually—by Norway for human consumption and by Japan for scientific use, although whales are also eaten in Japan.
One rationale proposed for eating whale meat is that whales eat many fish that could instead be caught by humans.
Another industry that has recently been criticized for damaging whales’ ecosystems is the tourism industry—whale- watching tours are said to disrupt whale migration patterns and cause the whales undue stress
Importance of mangrove swamps
The importance of mangrove swamps has been well established.
They function as nurseries for shrimp and recreational fisheries, exporters of organic matter to adjacent coastal food chains, and enormous sources of nutrients valuable to plants, wildlife, and ecosystem function.
Their physical stability also helps to prevent shoreline erosion, shielding inland areas from severe damage during hurricanes and tidal waves.
Mining basics
Mining is the excavation of earth for the purpose of extracting ore or minerals.
We can divide mineral resources into two main groups according to how they’re used.
Metallic minerals are mined for their metals (for example, zinc), which can be extracted through smelting and used for various purposes.
Nonmetallic minerals are mined to be used in their natural state— nothing is extracted from them.
Examples of nonmetallic minerals are salt and precious gems.
Here are two more terms you should know for the exam, if you don’t already: a mineral deposit is an area in which a particular mineral is concentrated.
An ore is a rock or mineral from which a valuable substance can be extracted at a profit.
The cost of extracting minerals depends on numerous factors, including the location and size of the mineral deposit.
Additionally, the impetus for mining certain deposits more than others is often purely based on the value of the mineral resource.
Understandably, the higher the value of the resource, the more money and effort will be put into mining it.
Evnironmental concerns about mining
Environmental concerns about mining do not center on the depletion of mineral resources from the Earth’s surface.
Instead, they revolve around the damage that is done during the extraction process.
The extraction of a mineral from the Earth generally disrupts the ecosystem and scars the land.
Sometimes the extraction leaves pollutants that result from the surface exposure of underground minerals, from transformation of these minerals during mining, from chemicals or other substances introduced during extraction, or even from the machinery used for extraction.
Ex. acid mine drainage
Ex. acid mine drainage
deposition of iron pyrite and sulfur in the mining of coal.
The acid forms as water seeps through mines and carries off sulfur-containing compounds.
The chemical conversion of sulfur-bearing minerals occurs through a combination of biological (bacterial) and inorganic chemical reactions, and the result is the buildup of extremely acidic compounds in the soil surrounding the deposit.
These compounds create acid mine drainage that can severely harm local stream ecosystems.
Mining waste, lower grade ores
In mining processes, waste material is called gangue, and piles of gangues are called tailings.
As the more accessible ores are mined to depletion, mining operations are forced to access lower-grade ores. Accessing these ores requires increased use of resources that can cause increased waste and pollution.
Surface mining
the removal of large portions of soil and rock (this layer is called overburden, and it is whatever material lies above an area of scientific interest) in order to access the ore underneath.
Strip mining
An example is strip mining, which involves removal of the vegetation from an area, which makes the area more susceptible to erosion.
This type of mining is only practical when the ore is relatively close to the surface, which is why it’s used mainly for coal mining.
This is the least expensive—and least dangerous—method of mining for coal.
However, because strip mining requires removing massive amounts of topsoil, it has a much greater impact on the surrounding environment than underground mining.
The most extreme form of strip mining, mountaintop removal, transforms the summits of mountains and destroys ecosystems.
This method is mostly associated with coal mining in the Appalachian Mountains.
As coal reserves get smaller, due to a lack of easily accessible reserves, it becomes necessary to access coal through subsurface mining, which is very expensive.
shaft mining
Vertical tunnels are built to access and then excavate minerals that are underground and otherwise unreachable.
Another environmental drawback to mining is that the refinement of these minerals often requires extensive energy input.
For example, it takes approximately 15.7 kW of electricity to produce one kilogram of pure aluminum from its ore.
On the other hand, recycling aluminum requires only 5 percent of the energy that’s required to smelt it, and generates only 5 percent of the greenhouse gases.
After minerals have been extracted from their ore, they may be used in their rough form or further processed.
Aluminum, for example, must be further refined after it is mined. Coal is an exception.
After mining, it is transported to a power plant and burned in its original state.
Sometimes two metals are combined to form a product; this is the case with stainless steel, which is a combination of iron and either nickel or chromium, and regular steel, which is 95.5 percent iron and 0.5 percent carbon.
Because of the energy expended in mining and extraction, the steel industry is responsible for much of the air pollution that exists today!
Fortunately, air, land, and water harmed by mining can be reclaimed through mine restoration projects
Most humans live in cities, suburbs
The majority of humans live in some type of community, and the largest percentage of the human population lives in relatively large communities and urban centers.
In the United States, this is partly due to the fact that our aging population has largely moved into the cities to have greater access to health services, employment opportunities, and cultural activities.
When considering those who live in urban areas, we also count those who reside in satellite communities, or suburbs.
urban sprawl
In recent times, with lower oil prices making it easier for people to afford gasoline to commute to and from their jobs in cars, people have moved out of city centers in order to have more living space.
Interestingly, people who live in the suburbs, on average, occupy eleven times more space than do those who live in the city.
One of the advantages of living in the suburbs is that people have their own land space —a backyard—which they need not share with others.
The term used to describe the emigration of people out of the city and into the suburbs is urban sprawl.
In some areas of the United States, urban sprawl takes over vast tracts of land.
In Colorado, for example, population growth has resulted in a number of new communities between Denver and Boulder; when traveling between the two cities, it is now difficult to determine where the Denver metro area ends and the city of Boulder begins.
Urbanization, strain on urban areas
When urban areas grow too large and become too dense, distributing water to all citizens becomes increasingly difficult.
Coupled with this is the strain on the water supply—more people means more water use.
In many of these newly crowded areas, water shortages have led to the implementation of restrictions on water usage.
Additionally, urbanization impacts the ecosystem in which a city is located rather a lot.
The sheer number of people using resources in such a densely packed cluster puts a strain on those resources far more than in any other location—and not just the water supply.
The burning of fossil fuels for industry, transportation, and electric power releases greenhouse gases and affects the carbon cycle.
The sheer weight of buildings and roads compacts the soil.
Increased runoff
Increased waste is created
Brownfields
INcreased runoff
the impervious surfaces that make up so much of a city’s footprint— concrete, pavement, etc.—do not allow water to reach the soil, disrupting the natural flow of water and causing runoff, which can lead to flooding without more infrastructure to redirect flow.
Methods to increase water infiltration (reducing runoff) include replacing traditional pavement with permeable pavement, planting trees (which redistribute water more evenly), increased use of public transportation (to reduce road usage), and building up, not out (decreasing a city’s overall “footprint”).
Runoff matters, because without the normal amount of water flowing into it, soil can become salinized and saltwater can intrude into the water table.
Even the ubiquitous front lawn is often at complete odds to what the natural ecosystem of an area would look like, and the pesticides used to keep lawns looking up to social standards add to the number of pollutants present.
