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2. Chapter Two: Principles of Ecology: Matter, Energy and Life
from your text, Principles of Environmental
Science: Inquiry and Applications, 2nd ed.
William and Mary Ann Cunningham. (New York: McGraw-Hill, 2003)
This slide set includes material from Chapter Two: Principles of Ecology: Matter, Energy and Life.

3. Required Reading
Chapter Two: "Principles of Ecology: Matter, Energy, and Life.” from your text, Principles of Environmental Science: Inquiry and Applications. 2nd ed. William and Mary Ann Cunningham. (New York: McGraw-Hill, 2003) .
Read all of chapter 2 in your text, Principles of Environmental Science: Inquiry and Applications. 1st ed. Cunningham and Cunningham: New York: McGraw-Hill, 2002.

4. Chapter Two Objectives
At the end of this lesson, you should be able to
describe matter, atoms, and molecules;
list the four major kinds of organic compounds in cells; give simple examples of their roles
define energy, and explain the difference between kinetic and potential energy;
explain the principles of conservation of matter and energy and describe how the laws of thermodynamics affect living systems;
explain how photosynthesis captures energy for life and how cellular respiration releases that energy to do useful work in a cell;
define species, populations, biological communities, and ecosystems, and understand the ecological significance of these levels of organization;
discuss food chains, food webs, and trophic levels in biological communities, and explain why there are pyramids of energy, biomass, and numbers of individuals in the trophic levels of an ecosystem; and
explain the importance of material cycles, such as carbon and nitrogen cycles, in ecosystems.
After you have studied chapter 2 and this slide set, review the objectives above to test your understanding of the material.

5. Chapter Two Key Terms McGraw-Hill Course Glossary
Ecosystem
Energy
First law of thermodynamics
Food web
Herbivores
Ions
Kinetic energy
Matter
Metabolism
Molecules
Nitrogen cycle
Omnivores
Acids
Atom
Bases
Biological community
Biomass
Carbon cycle
Carnivores
Cellular respiration
Compound
Conservation of matter
Consumers
Decomposer
Ecology
Organic compounds pH
Photosynthesis
Potential energy
Primary producers
Productivity
Second law of thermodynamics
Species
Tropic level
Note the key terms for chapter 2. After reading chapter 2 and the slide set, see if you can define each term. You can consult the McGraw-Hill course glossary (see link above) if you have an Internet connection.

6. Chapter Two - Topics Energy and Matter in the Environment
Organizing Living Things: Species and Ecosystems
Biochemical Cycles and Life Processes
Chapter 2 starts with some important topics including energy and mater in the environment, species and ecosystems and how living systems are organized, as well as biochemical processes and processes of life related to chemistry.

7. Part 1: Energy and Matter in the Environment
To understand how ecosystems function, it is important to first know something about how energy and matter behave - in the universe and in living things. It is also important to understand the basic building blocks of life, starting with cells and organisms, and proceeding to communities and populations.
In order to understand the environment completely, we need to understand ecosystems. These are complex constructs that obey basic principles of conservation of matter and energy. To understand ecosystems, we first need to study the basics building blocks of life, including cells and organisms and then their combination into communities, populations and ecosystems. Most of this we encounter later on in the course.

8. Interrelated Scientific Principles: Matter, Energy and Environment
We can use the model shown above to understand and predict environmental consequences. For instance we understand to a certain extent the way matter is put together in living things and non-living things, how energy is utilized by organisms and how it flows independently of life. The interactions of matter and energy are what lead to an environmental consequence of any give set of circumstances.

9. Ecology
The scientific study of relationships between organisms and their environment
Examines the life histories, distribution, and behavior of individual species, as well as the structure and function of natural systems at the level of populations, communities, ecosystems, and landscapes
Encourages us to think holistically about interconnections that make whole systems more than just the sum of their individual parts
Examines how and why materials cycle between the living and nonliving parts of our environment
We also have some terms that we need to consider. Sometimes the way that environmental terms are used in society and the press is confusing. Scientifically speaking, the term ecology refers to the study of the relationships between living organisms and their environment. The environment can be composed of living and non-living things. Extending this idea, ecology can encompass life history, distribution, and behavior of individual species and the structure of the way that natural systems work.
Systems can be divided into levels including individuals, populations of individuals, and communities, which include a number of different species that are interrelated; and ecosystems, that extend that relationship to nonliving things. The next level of organization is landscapes. which might include multiple ecosystems, communities, populations. and of course individual organisms. Ecology encourages us to think holistically to recognize the interconnections that make a system more than just the individual organisms and parts added up. It also considers how matter and energy cycle between living and nonliving parts of the environment.

10. Matter and Energy
Matter and energy are essential constituents of both the universe and living organisms.
Matter - everything that takes up space and has mass
Energy - the capacity to do work
So let's continue with our definitions. Most people understand matter and energy as essential constituents of organisms and the universe. Matter is something that has mass and that takes up space within the environment, and energy is the ability to do work, or move matter through a gradient. Matter and energy are related. Einstein considered them to be much the same thing in his theory of relativity, but we don't have to extend a consideration of matter and energy that far in ESC110, except for a consideration of nuclear energy.

11. Potential vs. Kinetic Energy
Figure 2.1 text
Potential energy - stored energy that is latent but available for use
Kinetic energy - the energy contained in moving object
Energy has two forms, potential and kinetic. Potential energy is stored energy, either physical, chemical or nuclear. The energy contained in a piece of coal, behind a hydro dam, or within uranium is potential energy. Kinetic energy is energy that is actually acting on and moving matter.

12. Heat and Temperature
Heat - describes the total kinetic energy of atoms or
molecules in a substance not associated with bulk motion of the substance
Temperature - a measure of the speed of motion of a typical atom or molecule in substance
Heat and temperature are not the same. A substance can have a low temperature (low average molecular speed) but a high heat content (much mass and many moving molecules or atoms). For example, a lake might feel cold to your hand, but it contains an immense amount of stored heat.
Many people think of heat and temperature as the same thing, but they aren't. Heat is the total kinetic energy, the movement of atoms in molecules in a substance. It's not associated with the movement of that substance itself, but its vibration. Temperature is a relative measure of motion of atoms and molecules in a substance.

13. Energy Quality Low Quality Energy
Diffused, dispersed, or low in temperature
Difficult to gather and use for productive purposes
Example: heat stored in the oceans
High Quality Energy
Intense, concentrated, or high in temperature
Useful in carrying out work
Example: high-voltage electrical energy
Many of our most common energy sources are low-quality and must be concentrated or transformed into high-quality sources before they are useful to us.
The use of energy is one of the basic needs of society. In thinking how society uses energy from the environment, it's important to understand the difference between low quality energy, or diffuse energy, and high quality, or concentrated energy. Diffuse energy is hard to gather and use. High quality energy can be converted and utilized easily. For instance, energy in gasoline can be used in an internal combustion engine, the energy in food can be used by living organisms and electrical energy can be used in a variety ways to do useful work. These are concentrated energy forms. Most energy in the environment is of low quality and we often spend effort concentrating that energy so that we can utilize it for some useful purpose.

14. Conservation of Matter
Under ordinary circumstances, matter is neither created nor destroyed. It is recycled endlessly.
Matter is transformed and combined in different ways, but it doesn't disappear. Everything goes somewhere.
The atoms and molecules in your body have passed through many other organisms, over millions of years.
Two other things that are important about matter and energy are the potential for reuse. Matter itself is not created or destroyed as it's used, and theoretically, it can be recycled endlessly. On the other hand, matter is diffused and dispersed within the environment in such a way that it makes it very difficult to recover matter, just as it is difficult to recover diffused energy. Think of a brand-new car in New England, where they use salt to melt ice on winter roads. It would be very hard to recover all of the steel that has rusted and flaked off over thousands of miles of driving a car. This is a good example of matter dispersion into the environment.

15. Properties of Energy
Energy cannot be recycled. Energy is reused, but it
is constantly degraded or lost from the system.
Most energy used in ecosystems originates as solar energy. Green plants convert some of this energy to chemical energy, which is then converted to heat or kinetic energy by the animal that eats the plant.
Energy is very different than matter. Though energy can be reused, it can't be recycled. Energy is constantly degraded as it is used and converted into a less useable form. Energy in most ecosystems originates from the sun. However, entire ecosystems have been discovered that are not dependent on the sun for energy. For instance, off the coast of Washington, in deep ocean trenches, there are communities of organisms that get chemical energy from a chemical process called sulfide oxidation. However, for most ecosystems, green plants capture solar energy, and they pass that high quality energy on through energy systems called food chains.

16. Laws of Thermodynamics
First Law of Thermodynamics
Energy cannot be created or destroyed, only changed
Second Law of Thermodynamics
With each successive energy transfer or transformation in a system, less energy is available to do work. Even though the the total amount of energy remains the same, the energy's intensity and usefulness deteriorate.
The second law recognizes the principle of entropy, the tendency of all natural systems to move towards a state of increasing disorder.
It is useful to consider the two laws of thermodynamics when considering energy in the environment. The first law says that energy cannot be created or destroyed, only changed. The second law introduces a concept called entropy, which is the tendency to move to a state of increasing disorder. This concept is extremely important in environmental science. Basically, it says that as energy is used, it is difficult to recapture and reuse it. The total amount of energy will remain the same but its intensity, concentration, and thus usefulness would deteriorate through each use. This explains why my office is so messy. Each and every evening I am not cleaning and straightening, so it tends toward increasing disorder, and after returning from a recent vacation, it was really a mess ;>)

17. Atoms, Molecules, and Compounds
Most material substances can exist in three interchangeable states: solid, liquid, or gas.
Element - substance that cannot be broken down into simpler substances by ordinary chemical reactions
Atom - the smallest particle that exhibits the characteristics of an element
Molecule - a combination of two or more atoms
Compound - a molecule made up of two or more kinds of atoms held together by chemical bonds
Matter has some distinctive forms and is made of distinctive components. Most matter exists as solid, liquid or gas, and we can describe our earth in that way as well to certain extent. For instance, the atmosphere would be the gas, the oceans would be the liquids, and the land would be the solids. Of course there are mixtures of those.
Elements are substances that can't be broken down into simpler substances, at least by chemical reactions. It requires nuclear reactions to change them.
An atom is the smallest particle that exhibits the characteristics of an element' for instance, gold is composed of gold atoms.
A molecule is formed when two atoms combine to form in some cases a very. very different substance that doesn't have the properties of either of its components.
A compound is held together by chemical bonds caused by sharing of electrons.
In an Environmental Science course, it is very important to recognize that life depends on a continuous series of chemical reactions. For example, the continuous series of chemical reactions in your body is what keeps you alive.
In some common uses, the word "chemical" implies negativity, such as in the statement, I don't like chemicals in my food! This is an example of inaccurate use of a "loaded" word, since in reality, all food is composed of chemicals. Be on the lookout for specific, technical Environmental Science terms that are used with different meanings outside of Environmental Science. Often, the context of the word is key. Consider the following: a) "better living through chemistry", and b) "I don't like chemicals in my food!"

18. Fig. 2.3
For an atom, the next step down is size is to the 3 particles called protons (positively charge), electrons (negatively charged) and neutrons (electrically neutral). The atom in this figure is carbon. As shown in its normal state, it has the same number of protons and neutrons. When an extra neutron is added, the atom becomes radioactive (various atomic weights of the same atom are called isotopes). Atoms with unequal numbers of protons and neutrons are unstable and spontaneously decay. The time it takes for one-half of the atoms to decay to the more stable state is defined as its half live. Half lives for atoms can be as short as a few seconds to as long as thousands of years.

19. Periodic Table of the Elements
This chart above is the periodic table of the elements. It depicts the 92 elements that exist in nature and another 21 that can be created artificially. Each element has distinct chemical characteristics. These elements represent a huge variety of potential chemical reactions that can take place.
Elements that are required by living organisms cover just about all potential types of chemical reactions that occur and range across the periodic table. Interesting enough, the elements helium, neon, argon, krypton and so on aren't generally part of living systems because they are stable elements that don't participate readily in chemical reactions. Life itself is base on dynamic chemical reactions. Stable is dead.

20. Elements and Environmental Science
In terms of Environmental Science, we can group these elements in terms of their usefulness and importance. Living things, for instance, are largely composed of the element carbon, which is the foundation for all known life on earth.
Hydrogen, oxygen and nitrogen also comprise a large amount of living material. In all, there are about 19 different elements that are required for living things to carry out their natural processes.
Our atmosphere is made up of about 4/5 nitrogen, 1/5 oxygen, and relatively small amounts of argon, carbon dioxide, neon and helium. The solid part of the earth is largely composed of iron, silicon, aluminum, and other elements. Some of these elements are very, very important to economy and society. These include iron, aluminum, chromium, copper, manganese and nickel. Other important elements are those that are potentially toxic such as uranium and lead; they can poison the chemical processes of life, causing organisms to function abnormally or even die.
Just four elements - carbon, hydrogen, oxygen, and nitrogen - make up over 96% of the mass of most organisms.

21. Chemical Bonding
Ionic Bond - Formed when one atom gives up an electron to another atom.
Covalent Bond - Formed when two or more atoms share electrons.
Energy is needed to break chemical bonds.
Energy is released when bonds are formed.

22. Fig. 2.4
Molecules have various shapes. The hydrogen atoms on a water molecule look like Mickey Mouse ears and carbon dioxide is linear. These shapes may help you put a personal touch to the molecules. More substantial, perhaps, is the fact that their shapes affect their chemical activity as is most important to the activity of water.

23. Water Molecule
In addition to elements that are critical for life, there are molecules that play key roles in most organisms. Water is an example of one of these molecules. Water is composed of two hydrogen atoms and one oxygen atom that share electrons. We will have a whole chapter on water later on in this course.

24. Water: A Unique Compound
Sixty to 70 percent of the weight of living organisms
Medium in which all of life's chemical reactions occur
Good electrical conductor
Highest surface tension of any common, natural liquid
Liquid over a wide temperature range
Expands when it crystallizes, unlike most substances
High heat of vaporization
High specific heat
Water is an extremely important and unique compound, making up about 70 percent of the weight of living organisms. Most of the chemical reactions important to life take place in water, and this is true in living as well as non-living systems.
Water, particularly water that contains dissolved substances, is a good electrical conductor. Water has a very, very high surface tension, which allows many organisms to float on it. Water remains liquid over a wide rage of temperatures, can exist as a solid in the form of ice, and as a gas in the form of water vapor.
Unlike most substances, water expands when it crystallizes and has its maximum density as a liquid just above its freezing point of 0 degrees Centigrade. Because ice is less dense than liquid water, ice doesn't sink to the bottom of lakes and rivers.
Water has a high heat of vaporization and a high specific heat and so greatly modifies environments that have lots of water. For instance, Seattle would be a much colder place in the winter and hotter in the summer if there was no Lake Washington and Puget Sound to moderate daily temperatures.

25. This side shows an organism, a water strider, that takes advantage of the surface tension of water to determine where it lives -- on the surface of water, where it can easily float. We will talk about how water cycles on our planet in Chapter 10.

26. A Chemical Reaction Chemical reactions, the breaking and forming of
We have to lay to rest very quickly in this course the concept of chemicals being anything more devious than they are. How many times have I heard people saying they don't want chemicals in their foods, when what they meant was that they don't want something like a pesticide in their food.
Chemical reactions, the breaking and forming of
molecular bonds, create all the simple and complex
compounds and substances on which life depends.

27. Acids and Bases
Acids are compounds that readily release hydrogen ions (H+) in water.
Bases are substances that readily take up hydrogen ions (H+) and release hydroxide ions (OH-) in solution.
Strength measured by concentration of H+.
pH scale
0-14
The pH of the environment has a profound effect on the chemical reactivity of substances and the character of life itself.

28. Fig. 2.5
02_05.jpg

29. Cells: The Fundamental Units of Life
Microscopic organisms, such as bacteria and protozoa, are composed of single cells.
The human body contains several trillion cells of about two hundred distinct types.
Enzymes – catalysts that speed up the rate of chemical reactions in living systems
Metabolism - all the energy and matter exchanges that occur within a living cell or organism
So, we accept that chemicals are the building blocks of life and chemical reactions are the basis for life. Cells are the constructs of those life process, the fundamental basis of life. There are some organisms that are single celled, for instance bacterial and protozoa, which are usually so tiny that we can't see them without a microscope.
The human body is an example of a multi-cellular organism composed of several trillions cells differentiated into about two hundred distinct types of cells that carry on different functions within the body. For instance, a hair cell is very, very different than a bone cell or blood cell, and different cells typically have different functions. All cells have molecular catalysts called enzymes that are designed to carry out certain kinds of chemical reactions. Enzymes enable certain chemical reactions to take place in cells, including those reactions that turn food into energy. Metabolism is a general term for these changes.

30. The Electromagnetic Spectrum
The wavelengths of visible
light drive photosynthesis.
We have mentioned that light radiation from the sun is the source of energy for most of life. The part of t he electromagnetic spectrum that includes light encompasses a wide range of frequencies, and what we can actually see as visible light is a very narrow band within that range. Photosynthesis of plants is driven by the narrow range of visible light, ranging from about micrometers.
Other wavelengths can have effects on the environment; for instance, x-rays and gamma rays can be deadly, ultraviolet radiation gives us a sun tan, and also, potentially, skin cancer. Infrared energy heats us, and we use microwaves and radio waves to transmit energy. I'm particularly fond of using microwave energy to heat my lunch.

31. Photosynthesis
Light energy from the sun is relatively diffuse, and the process of photosynthesis converts it into more concentrated chemical energy that organisms can use. You likely heard about photosynthesis way back in elementary school. However, in case you weren't listening, we'll review how photosynthesis works.
Using light energy from the sun, plants convert carbon dioxide, nutrients, and water into complex carbohydrate molecules that can be used by many different types of organisms, including humans. Another way of describing photosynthesis is to say that the process "fixes,” or captures, the light energy of the sun into carbohydrate molecules.
Consider that the energy in a glass of milk we might drink for lunch originally came from the sun's light energy, and through photosynthesis, was "fixed” by grass. The grass was eaten by a cow, and the cow used the energy for a variety of chemical reaction, including making milk. The human drinking the milk uses the energy for a variety of chemical reactions. If you were a plant, you could lie out in the sun and make your food, but since you're not, you depend on plants directly or indirectly—by eating animals--for your food. Plants ultimately depend on the sun.
Earlier, I mentioned that some systems, like communities in deep ocean trenches and algae in the very hot Morning Glory pool in Yellowstone Park, utilize energy directly from chemicals from the earth, not the sun.

32. Light and Dark Reactions of Photosynthesis
This is another representation of how light energy is converted to chemical energy in photosynthesis. The process depends on chlorophyll, water, and carbon dioxide, with carbohydrates such as sugar being produced as the product of the reaction. Carbohydrates exist in many forms in the environment – as sucrose, glucose, and cellulose, for example.
Light and Dark Reactions of Photosynthesis

33. Respiration
For many organisms, the utilization of the complex carbohydrates produced by photosynthesis through cellular respiration is the immediate source of energy. The key is that photosynthesis took solar energy and concentrated it into a useful form of potential energy, and cellular respiration releases that potential energy. For instance, in the image above we see a runner using energy produced by cellular respiration of food to move her body. Part of that energy is then released as kinetic energy. Much of the rest is lost as heat energy.
Note: Cellular respiration is a different process than the respiration of breathing.

34. Energy Exchange in an Ecosystem
That original energy captured from the process of photosynthesis can be cycled multiple times within ecosystems on many levels. For instance, photosynthesis can produce sugars and other carbohydrates which then can be used by plants. Grazers such as mice can then eat those plants. Larger animals like cats can eat the mice. In the first step of photosynthesis, carbon dioxide is taken out of the atmosphere. The utilization of that stored chemical energy through cellular respiration releases carbon dioxide back to the atmosphere. Thus, there is a symbiosis, or mutually beneficial relationship between energy concentrators, for instance green plants, and energy "utilizers,” including green plants and other organisms.

35. Part 2: Organizing Living Things
Organism
Population
Biological
Community
Ecosystem
Biosphere
Organisms in the environment are organized into various different levels, often in complicated, intricate, and very interesting ways. The first level is an individual organism. The next level is that of populations, a group of organisms of the same species considered together. A biological community is an assemblage of organisms that are related to each other in various ways and usually dwell in the same relative geographic area. An ecosystem expands the concept of communities to include the cycling of the matter and energy within a system. (The word "ecosystem” combines the words "ecology” and "system.”) The biosphere includes all living organisms and their physical environment.

36. Food Web: Cross-connected Food Chains
You probably heard about the food chain in your elementary school classes. Ecosytems typically have multiple chains at several levels such as that depicted in the diagram above. For instance, the diagram shows that plants grow in the pond, snails eat the plants, a bass might eat the snails, and an osprey might eat the bass. This sequence would indicate a food chain. When there are several producers (plants) or consumers (animals) and several paths for food and energy to flow, cross connections known as food webs are created.

37. The diagram above shows how we classify organisms in relationship to how they acquire food -- producers, primary consumers, secondary consumers, and tertiary consumers. There are typically very few tertiary-level consumers because of the loss of energy during the transfers to each level….remember the two laws of Thermodynamics. We can't get away from their limitations.

38. Energy Pyramid
At each step, or trophic level, in the food chain, energy is transferred from one organism to another, and, as predicted by the second law of thermodynamics, it is not completely recycled and not completely utilized. Most of the energy transferred at each trophic level is dispersed into the environment as heat, a form of energy that can't be recovered or reused.
We can consider that we are using the increasing entropy of the sun to provide order and concentrated energy here on earth. Of course, since the sun will probably exist for a few billion more years, that's pretty much a limitless source of energy in terms of human existence. Humans have existed perhaps a million years on earth, and will be will be gone far before the sun burns out.
Most energy in most ecosystems is stored in the bodies of primary producers. Only about 10 percent of the energy at one energy level passes to the next highest trophic level.

39. Bioaccumulation
Lake Laberge, a remote lake in northwestern Canada, has been affected by organic chemicals that have been transported thousands of kilometers by wind and weather. The biggest fish in the lake are extremely contaminated due to bioaccumulation, a steady accumulation of toxins through food webs.
As an enormous amount of biomass and the energy contained in it is transported up through a food pyramid or web, substances can be concentrated at each additional trophic level. This process is called bioaccumulation.
A famous example of bioaccumulation was the concentration of DDT, an insecticide that was added to the environment in small concentrations. In every level of the food chain, DDT became more and more concentrated until it was at high enough levels that it affected bald eagles. The shells of bald eagle eggs couldn't form adequately, resulting in lowered reproduction. Bioaccumulation has also been seen in areas where chemicals have been transported over long distances, like Lake Laberge in the Yukon. In this remote and once pristine lake, chemicals have accumulated in the higher levels of the food web – fish. The concentrations of the chemicals are so high that people in the region have been advised to limit their consumption of certain fish from the lake.

40. The Carbon Cycle
Long range transport of many substances in the environment is common. Obviously, solid materials are more likely to stay in place, liquid materials move slowly by nature, and gases can be transported globally in periods as short as a few days. The diagram above shows the cycling of carbon in the environment. In particular, note the long range transportation of carbon dioxide, its fixation into plant material by photosynthesis, which makes it less mobile, and then the accumulation of plant material, which can be turned into a geologic material like coal and oil that cycles extremely slowly. In fact, most of the coal we use for energy has been in place for hundreds of millions of years and we use the term "fossil fuels" to describe its age.

41. The Nitrogen Cycle
Nitrogen is also an important element with global significance. Nitrogen is a very important nutrient for plants, and its absence often limits the productivity of plants. In particular, in the Pacific Northwest, the ultimate productivity of most forest land is limited by the lack of available nitrogen. The earth's atmosphere is about 79% nitrogen, but plants cannot use atmospheric nitrogen.

42. Nitrogen Fixation The nodules on the roots of this plant contain
bacteria that help convert
nitrogen in the soil to a
form the plant can utilize.
This slide shows roots of a red alder tree tree, common in the Pacific Northwest. The numerous nodules on the roots contain bacteria-like organisms called Frankia. The relationship that has developed between these two species benefits each in different ways. The red alder provides photosynthesis products (food) to the Frankia. Frankia have the ability to take the nitrogen gas out of the air, which red alder can't use directly, and convert it into a form that the red alder can use. The nitrogen gives red alder a competitive advantage under certain circumstances in Pacific Northwest forests, and indeed, red alder is one of the most successful trees invading freshly disturbed land. land. Other species have to wait until nitrogen builds up in the soil over time.

43. The Phosphorous Cycle
Phosphorous is particularly limiting in tropical systems, but can also limit plant growth in the Pacific Northwest. Unlike nitrogen, there are no common forms of phosphorus that are gases. Thus, phosphorus typically cycles more slowly in the environment.

44. The Sulfur Cycle
The sulfur cycle is also important in nature. Sulfur can be released as sulfur dioxide in some cases and as hydrogen sulfite in other cases. Volcanoes are a mayor source of world-wide atmospheric sulfur. Sulfur has also been emitted by people digging up coal and other fossil fuels and then burning them. In particular, certain types of coal can contain significant amounts of sulfur, and when it is burned, it turns into sulfuric acid and creates a phenomenon called acid rain. We don't receive much human-made sulfur into the Pacific Northwest, but we have a tremendous upwelling current off the coast that brings sulfur from deep ocean vents (remember the deep-ocean communities?) to the surface where microorganisms convert it into dimethyl sulfide gas which then oxidizes into sulfuric acid.