CK-12 Life Science

by CK-12 Foundation

  Such waterborne diseases can be caused by protozoa, viruses, bacteria, and intestinal parasites. Protozoal infections can be caused by sewage, non-treated drinking water, animal manure, poor disinfection, and groundwater contamination; some viruses and bacteria are water-borne and can be found in drinking water, sewage, contaminated seafood, or unsanitary recreational water; and parasitic infections are usually caused by contaminated drinking water.

  Preventing Water Pollution

  In the U.S., concern over water pollution resulted in the enactment of state anti-pollution laws in the latter half of the 1800s, and federal legislation in 1899, which prohibited the disposal of any refuse matter into the nation’s navigable rivers, lakes, streams, and other bodies of water, unless a person first had a permit. In 1948, the Water Pollution Control Act was passed and gave authority to the Surgeon General to reduce water pollution.

  Growing public awareness and concern for controlling water pollutants led to enactment of the Federal Water Pollution Control Act Amendments of 1972, later amended in 1977, to become commonly known as the Clean Water Act. This Act established the basics for regulating discharge of contaminants and established the authority for the U.S. Environmental Protection Agency (EPA) to implement standards for wastewater discharge by industry. The Clean Water Act also continued requirements to set water quality standards for all surface water contaminants.

  More specifically, control of point sources of phosphorus through policy changes have resulted in rapid control of eutrophication. Nonpoint sources, on the other hand, are more difficult to regulate and usually vary with season, precipitation, and other irregular events. Nonpoint sources are especially troublesome because of soil retention, runoff to surface water and leaching to groundwater, and the effect of acid rain (See the Air Pollution lesson).

  On the hopeful side, though, cleanup measures have been somewhat successful. For example, Finnish removal of phosphorus started in the mid-1970s has targeted rivers and lakes polluted by industrial and municipal discharges. These efforts have had a 90% efficiency in removal. And with nonpoint sources, some efforts, like intercepting pollutants between the source and water, are successful (Figure below). Also, creating buffer zones near farms and roads is another possible way to prevent nutrients from traveling into waterways.

  Figure 25.12

  A water purification system at Bret Lake, Switzerland. Contaminants are removed and clean new water is created.

  In addition, laws regulating the discharge and treatment of sewage have led to dramatic nutrient reductions to aquatic ecosystems, but a policy regulating agricultural use of fertilizer and animal waste must also be imposed. One technique (Soil Nitrogen Testing, or N-Testing) helps farmers optimize the amount of fertilizer applied to crops and at the same time decreases fertilizer application costs, decreases the nitrogen lost to surrounding water resources, and sometimes decreases both.

  Actions aimed at lessening eutrophication and algal blooms are usually desirable. However, the focus should not necessarily be aimed at eliminating blooms, but towards creating a sustainable balance that maintains or improves ecosystem health. As you will see in the next lesson (25.3): Natural Resources, sustainable use is a useful concept for the use of resources as well. Can you think of some reasons why?

  Ways to Save Water

  While we will deal further with this topic in the next Lesson (25.3) on Natural Resources, we will examine here how saving water can also contribute to maximizing clean water for future use. In addition, preventing water pollution is one way of preserving precious water resources.

  One way to make sure that water is kept clean and conserved is the use of wastewater reuse or cycling systems, including the recycling of wastewater to be purified at a water treatment plant. By that means, many of the waterborne diseases, caused by sewage and non-treated drinking water, can be prevented.

  There are also various means of water purification, whereby contaminants are removed from a raw water source and at the same time create clean new water. Atmospheric water generation is one technology that can provide high quality drinking water by extracting water from the air by cooling the air and thus condensing the water vapor.

  Figure 25.13

  Sand processing Mill, near Provodin, Czech Republic. Water is used to wash mined sand, then is drained into tanks, filtered, and recycled.

  Reclaimed water, or recycled water (Figure above) that is treated and allowed to recharge the aquifer, is used for non-drinking purposes, so that potable water is used for drinking. This helps to conserve high quality water.

  Another way to reduce water pollution and at the same time conserve water is via catchment management. This is used to recharge groundwater supplies, helps in the formation of groundwater wells, and eventually reduces soil erosion, one cause of pollution, due to running water.

  In addition, both developed and developing countries can increase protection of ecosystems, especially wetlands and riparian zones (areas located on the bank of a waterway, like a river, or sometimes along a lake or tidewater). Not only do these measures conserve biota, but they can also make more effective the natural water cycle flushing and transport that make water systems more healthy for humans. What are some ways you can save water in your own house or community in order to increase the resource of clean water, to be made available to everyone?

  Lesson Summary

  There are two primary sources of water pollution, point source and nonpoint sources.

  Specific contaminants causing water pollution include chemicals, pathogens, and physical or sensory changes.

  Water pollution can affect both ecology and human health.

  One effect of water pollution is eutrophication, which can cause detrimental effects on aquatic ecosystems as well as on human life, including health.

  Water pollution also causes ocean acidification, which impacts oceanic calcifying organisms.

  Contaminated groundwater can lead to poisoned drinking water and various health problems, including cancer.

  A variety of water pollutants can cause waterborne diseases.

  Various legislation has regulated discharge of contaminants into water resources and led to dramatic nutrient reductions, but more can be done, especially in areas such as the agricultural use of fertilizer and animal waste.

  Different ways of saving water can also have an impact on our clean water supply.

  Review Questions

  When is water considered polluted?

  Name some sources of nonpoint source pollution.

  Lakes often become polluted as a result of point source pollution release of phosphorus from sewage plants. By what process would the release of phosphorus affect a lake’s vegetation growth and how would this in turn affect reductions in water quality and fish and shellfish populations?

  Name some sources of pollutants that can cause waterborne diseases.

  Why are nonpoint sources of pollution so difficult to regulate?

  Why might floating plastic debris be a problem for marine life?

  Further Reading / Supplemental Links

  Unabridged Dictionary, Second Edition, Random House, New York, 1998.

  http://www.epa.gov/region5/students/water.htm

  http://www.cdli.ca/CITE/water.htm

  http://www.epa.gov/region5/students/waste.htm

  http://en.wikipedia.org

  Vocabulary

  algal bloom

  Excessive growth of aquatic vegetation or phytoplankton as a result of eutrophication.

  aquifers

  Geological formations that contain or conduct groundwater.

  catchment management

  Method used to recharge groundwater supplies, help in the formation of groundwater wells, and reduce soil erosion.

  desalination

  An artificial process by which saline water is converted to fresh water.

  eutrophication

  An increase in nutrients, specifically compounds containing nitrogen or phosphorus, in an
ecosystem.

  frozen water

  Found in icebergs and glaciers.

  nonpoint source pollution

  Contaminants resulting from a cumulative effect of small amounts of contaminants gathered from a large area.

  ocean acidification

  Process whereby the oceans’ uptake of anthropogenic carbon dioxide from the atmosphere causes an ongoing decrease in ocean pH.

  point source pollution

  Contaminants that enter a waterway or water body through a single site.

  surface water

  Water found in rivers, lakes, or freshwater wetlands.

  waterborne diseases

  Diseases caused by organisms transmitted via contaminated water.

  water pollution

  The contamination of water bodies by substances, mostly anthropogenic, which cause a harmful effect on living organisms.

  Points to Consider

  Even though water is a renewable resource, there is not always availability of clean water. Control of water pollution, such as removal of phosphorus or creating buffer zones near farms, helps to preserve this renewable resource for the future.

  Methods such as wastewater reuse, atmospheric water generation, reclaiming water, catchment management, and protection of aquatic systems can all contribute towards the dual goals of keeping water clean and also available for future generations.

  Lesson 25.3: Natural Resources

  Lesson Objectives

  Explain what natural resources are.

  Describe renewable resources.

  Explain what nonrenewable resources are.

  Discuss the use of fossil fuels as an energy source and what energy sources are available as alternatives.

  Discuss how reducing, reusing, and recycling can help conserve resources.

  Check your Understanding

  What are our natural resources?

  What is the difference between a renewable and nonrenewable resource?

  Introduction

  There are many natural resources all about us. Which ones seem the most obvious? Which do you use on a regular basis? Which do you think you could keep using and they would never run out? After thinking about some of these resources, you will see how important an understanding is about what we do use in our daily lives, which of these resources will run out, and what we can do in our daily lives to help prevent them from running out.

  As we also examine our energy needs, we will see that fossil fuels are only one source of energy. Just because we use these on a daily basis does not make them necessarily the best choice. What are some of the benefits and detriments to using fossil fuels for energy? Can you think of some alternative energy sources that make the most sense, both from an energy point of view, and also economically? Finally, what can you do, in your home, school, and community to reduce unnecessary use of resources, and to reuse and recycle them when possible?

  What are Natural Resources?

  A natural resource is a naturally occurring substance which is necessary for the support of life. The value of a natural resource depends on the amount of the material available and the demand put upon it by organisms.

  What resources do you use on a daily basis? The ones that may come to mind right away are the ones we already looked at in the last two lessons: air and water. What else is absolutely necessary to your survival? The food you eat seems pretty obvious. Could you survive with just air, water, and food? Are other resources, like the land you live on, the house you live in, the gasoline your parents put in the car and the tools you use at home or at school absolutely necessary for survival and if not, should they be considered resources too?

  As you start thinking about what are natural resources for humans, compare these to what are natural resources for organisms other than humans. Perhaps it might seem a bit clearer as to what are resources for other organisms, since their lives are much simpler than ours and they really use resources for survival rather than for making their lives more desirable.

  As we will see later in this lesson, of all living organisms, humans have the greatest impact on natural resources. Therefore it is our responsibility to make sure we do everything we can to use resources wisely.

  Renewable Resources

  A resource is renewable if it is replenished by natural processes at about the same rate at which humans use it up. Examples of this are sunlight and wind (Figures below and below ), which are very abundant resources and in no danger of being used up. Tides are another example of a resource in unlimited supply, as well as hydropower, which is renewed by the Earth’s hydrologic cycle.

  Figure 25.14

  Solar radiation and wind energy are considered renewable resources because availability of both far exceeds our rate of consumption. 89,000 TW (terawatts) represents the amount of sunlight that falls on the Earths surface, 370 TW depicts wind energy available, and 15 TW was the global rate of energy consumption in 2004.

  Figure 25.15

  Wind power, another renewable resource, shown here in a modern wind energy plant.

  Based on what you learned in the last two lessons, would you say air and water are renewable resources? They may appear to be, but your knowledge about air and water pollution would tell you that clean air and water are not always so accessible. As we think about other resources, like soils, plants and animals, minerals, and energy resources let’s keep in mind about whether these are truly renewable or not.

  For example, soils are often considered renewable, but because of erosion and mineral depletion, this is not always the case (Figure below). Living things, like forests and fish, are considered renewable because they can reproduce to replace individuals lost to human consumption. However, overexploitation of these resources can lead to extinction.

  Figure 25.16

  Soil (Stagnogley) as a resource, showing a mixture of eroded rock, minerals, ions, partially decomposed organic material, water, air, roots, fungi, animals, and microorganisms, formed over thousands, possibly millions of years.

  Also think about at what costs resources can be renewed. If something can be renewed, but at great cost economically or ecologically, is that resource still considered renewable? Perhaps a better way to put this is, does it make sense to renew a resource at great cost? If you’re thinking that this discussion is leading up to energy resources, you would be right!

  For example, energy resources derived from living things, such as ethanol, plant oils, and methane, are considered renewable, but the environmental costs are not always adequately considered. We will be discussing fossil fuels and alternative energy sources further in this lesson.

  Other renewable materials would include sustainable (at a rate which meets the needs of the present without impairing future generations from meeting their needs) harvesting of wood, cork, and bamboo, as well as sustainable harvesting of crops. Also, metals and other minerals are sometimes considered renewable because they can be recycled, and are not destroyed when they are used.

  Nonrenewable Resources

  A nonrenewable resource is a natural resource that exists in fixed amounts (relative to our time frame) and can be consumed or used up faster than it can be made by nature. It cannot be regenerated or restored on a time scale compared to its consumption. Two main types of nonrenewable resources are fossil fuels and nuclear power.

  Fossil fuels, such as petroleum, coal, and natural gas:

  Have formed from plant remains (for coal) and phyto- and zoo-plankton remains (for oil) over periods from 50 to 350 million years ago!

  Has been estimated that 20 metric tons of phytoplankton produce one liter of gasoline!

  Have been consuming fossil fuels for less than 200 years, yet remaining reserves of oil can supply our needs for only 45 years; of gas, for only 72 years; and of coal, for 252 years

  Nuclear power

  Limited uranium fuel supplies; could last 70 years at current rates of use.

  Known and unknown reserves are probably much larger.

 
New technologies could make some reserves more useful.

  Population growth; industrialization, especially in developing countries; and advances in technology place increasing pressures on how fast we consume natural resources. An unequal distribution of wealth, technology, and energy use suggest that developing nations will even further their increase of demands on natural resources (Figure below).

  Figure 25.17

  Per capita energy consumption (2003) shows the unequal distribution of wealth, technology, and energy use.

  That is not to say that all is doom and gloom either. Improvements in technology, conservation of resources, and controls in population growth could all help to lessen the demand on natural resources.

  Fossil Fuels and Alternative Energy Sources

  As you learned in the section on nonrenewable resources, fossil fuels, such as petroleum, coal, and natural gas, exist in fixed amounts, take millions of years to form naturally, and cannot be replaced as fast as they are consumed. They range from very volatile (explosive) materials like methane, to liquid petroleum to nonvolatile materials like coal.

  It was estimated in 2005 that 86% of primary energy production in the world came from burning fossil fuels. Concern about fossil fuels is one of the causes of regional and global conflicts, and the production and use of fossil fuels raise concerns about the environment.