PDS APES 5th Period 2009-10

On Wednesday we reviewed some of the qualities of soil.  To do this, we looked at a soil profile, and we also made our own edible version.

A soil profile is a view of the different layers of soil from the side, so it’s easy to separate each one.  These layers are also called horizons, and there are four  main ones that our text mentions- O, A, B, and C. Page 49 of our text has a good description as well.      http://soils.usda.gov/education/resources/lessons/profile/profile.jpg

A soil profile that contains the basic horizons.

Each of the horizons have distinct qualities that separate them from the others:

• O- This is made up of the seasoned, dead organic matter known as “leaf litter.” It contains detritivores, and other small insects. The material we collected during the Davidson field trip was the O layer.
• A- This is the topsoil. Combined with the O and E, which isn’t necessary to know, layers it makes up the zone of leaching. Humus is also found in this horizon. Humus is the nutrient-rich soil that is dark brown in color.
• B- This is the subsoil and the zone of accumulation.
• C- This is the parent material, which is made up of weathered, larger rocks. The R horizon lies below the C and is known as bedrock, but it isn’t necessary to know this layer either.

We then went on to make our own ice cream version.  First we added cookies, which were the R layer, next was the ice cream, which was the C layer.  On top of that we put whipped cream as the B layer and pudding represented the A layer. The O layer was a combination of nuts, chocolate chips, and other toppings. This helped us to visualize what makes up each of the horizons.

We also reviewed a soil triangle; it might be nice to make sure you know how to read one- clay is read on the horizontal, and silt and sand are read on the diagonal.

A soil triangle, notice how each one is read on different angles.

http://www.oneplan.org/Images/soilMst/SoilTriangle.gif

A review over the qualities of sand, silt, and clay:

Sand- It is the largest of the three and is very permeable, so it doesn’t retain water well. This results in lots of leaching, which causes nutrients to be lost because they are “leached” downwards through the horizons. This causes sand to have poor nutrient retention. On the other hand, it has very good water infiltration (absorption), but poor aeration.

Silt- It is the second largest and retains water and nutrients fairly well. Its aeration and ability to absorb water are fair too.

Clay- It is the smallest of the three, and  retains water and nutrients well.  However, it has poor water absorption and aeration.

A combination of the three soils makes the “best” type of soil, which is known as loam. Loam exhibits the best qualities of all three particles, which is why it’s so good.

That was about it, so I hope this helps anyone who needed a review of soil!

Okay, so I had a question on waste-to-energy incinerators.  Are all incinerators waste-to-energy? Do they all produce excess energy that can be used as electricity or for other uses?  I just didn’t know if there were special incinerators that were waste-to-energy or if they were all like that.  Also, in the book it says that these incinerators “boil water to make steam,” so does that mean after the waste has been burned there is water left over?  I’m just a little confused on the process, and the diagram 16-10 isn’t helping me much.

Today in class we discussed oil spills: their sources, effects, clean-up, and solutions.

There are various sources of oil spills: offshore wells, tankers, pipelines, storage tanks, and runoff from highways, which is the top source.

There are three main effects of oil spills: death of organisms, loss of animal insulation and buoyancy, and smothering.

Sea otters and sea birds are two organisms severely harmed by oil spills because the oil gets trapped in their fur or feathers, preventing them from insulating themselves (resulting in the organisms freezing) or flying (so they drown).

The three clean-up methods are: It is much easier to clean up crude oil, which has been claimed to take only three years, than refined oil because of all the additives in it.

• mechanical: booms, skimmers, and blotters
• chemical: coagulants and dispersing agents
• biological: bioremediation-this method uses natural bacteria in the water to consume the oil, and it is one of the most efficient ways to clean-up oil spills.

Many of these methods were used by Exxon in the movie we watched in class today, Scientists and the Alaska Oil Spill, which was made by Exxon in 1992. There are other methods described at the website below, such as containment and burning. http://science.howstuffworks.com/cleaning-oil-spill.htm

There are also a few solutions to oil spills that we discussed. The most effective one is prevention. Other solutions include double-hull tankers, relying less on oil and finding an alternative energy source, or creating legislation.

One recent form of legislation is the Oil Pollution Act (OPA) of 1990, which set up a trust fund financed by a tax on oil. This trust is able to clean-up spills when the guilty company is unable or unwilling to do so. The OPA requires oil storage facilities and vessels to propose plans describing how they will react to large spills so an oil spill like the Exxon Valdez, the worst oil spill in U.S. history, never happens again. New laws could reduce the number and severity of oil spills as long as they are efficiently enforced and not unreasonable to ask of the industry and the citizens.           http://www.epa.gov/lawsregs/laws/opa.html

The movie we watched in class today was about the Exxon Valdez oil spill that occurred in the Prince William Sound in 1989. Exxon gives the impression that the spill wasn’t too bad and they did everything they could to clean it up. They failed to leave out the cause, the captain being under the influence, and also the horrible losses that the fish and the fishing industry experienced. The movie describes Exxon’s two main goals after the accident as being:

1. To help oiled wildlife recover (such as sea otters and bald eagles)
2. To remove oil from the environment. Exxon claims to have removed all the oil by 1992; however, a BBC news article disagrees with those claims. If anyone is interested, this is the link to the article: http://news.bbc.co.uk/2/hi/science/nature/8465607.stm.

I hope this helps clarify any doubts!

Question 32 on the study guide asks what is the most sustainable form of meat production/consumption, and I wrote down that shifting from animal protein (like beef or pork) to poultry or herbivorous farmed fish would be the most sustainable form, but I don’t really understand why.  Is it because less grain is used to feed the animals, which will help the environment by reducing the large-scale agriculture?  

Also, question 35 asks about bycatch. We learned about that from the movie, but I wrote down that because it isn’t profitable, it is chopped up and pumped back into the ocean, which we didn’t see in the movie.  The bycatch, such as the shark, was just thrown back in dead but as a whole animal, so I was just wondering if those are just two different ways to dispose of bycatch, or if I’m misunderstanding what I wrote from the book.

Okay so question seven on the study guide asks for pros and cons of trace chemicals in the human body, and I just wasn’t exactly sure if what I got from the book was right.  One con I wrote down was that “less amounts of trace chemicals are found in the air,water, and food, but that leaves a false impression that chemicals are increasing.”  I don’t understand that at all because it seems like the opposite.  If there are less in the air, wouldn’t that leave the impression that the chemicals are decreasing, which could potentially be misleading? I’m not sure if I just wrote that down wrong or am totally misunderstanding it, so any help would be great. Thanks!

Okay so I have two questions.  The first one is from question 22 of our study guide.  I think I understand the idea of a biosphere reserve, it’s basically an inner core with two buffer zones that are used by locals, which protects the inner core.   I don’t understand is won’t the buffer zones be depleted of their natural resources eventually if they are continually used over a period of time?  And then people will want to use the inner core after all?

My second question deals with intrinsic and instrumental value.  Is intrinsic value similar to preservation and instrumental similar to conservation?  That was a simpler way for me to remember them, so if anyone can help me out that would be great!

Okay so a couple of questions.  On test number 1, one of the short answer questions was, “explain tragedy of the commons.”  I feel like I should know what that means, but i still don’t really understand, so if anyone could explain what they put it might help me out.  Also, does anyone know if the equations from that one quiz a long time ago will be one the exam? I can’t remember what he said about that.  And lastly, still from test number 1, one of the multiple choice (22) asks what a conservationist’s motivation is, and I always thought it was moral, but it’s utilitarian.  Is that because they want to wisely use the resources? If anyone can help explain these a little more that would be great! Thanks!

Okay so for number 22 on the study guide, one of the trends I wrote down from the book was “urban growth is much slower in developed countries than in developing countries.”  I understand why populations would increase more rapidly in developing countries, but I’m confused as to how urban growth is greater in developing countries because they don’t have the means and technology to be more urbanized, or at least that’s how I was looking at it.

Also, I don’t understand a demographic trap.  What exactly is it?

I think I missed the day when we covered evolution, and I was looking over microevolution and macroevolution, and I just wanted to make sure that I understand it correctly because I’m a little confused. Is macroevolution only creating a new species from an already existing one? It seems as if there should be more to it then that, so I’m not sure if I’m missing any aspect of it. Also, microevolution only alters gene pools, so is that physical appearances, such as the mice example Andy used? Does microevolution help select for certain species by making them more able for survival? If someone could clarify for me that would be great, thanks!

At the beginning of class today we started with a review of natural selection. The primary components that make natural selection possible are:

1. Genetic Variation (due to meiosis and mutation)

2. Overproduction of offspring

3. Struggle for existence

4. Different rates of survival and reproduction

Now back to the main topic of class today. We started off giving a simple definition of niche, which is an organisms job; however, there is more to a niche than it just being a job. A niche is multidimensional. It includes an organisms role in energy flow, interactions with other organisms, use of resources, and its functional role (trophic level).

http://www.bbc.co.uk/schools/gcsebitesize/science/images/bioaktree.jpg

Different organisms each have their own niche, or job, in different areas of an ecosystem.

The example we looked at was that of the Pitcher plant and the Red Crab Spider. The Red Crab Spider lives inside the Pitcher plant, which captures the spider’s food,  and the spider then provides the Pitcher plant with nutrients. Those are the “jobs” of the Pitcher plant and Red Crab Spider within a certain environment, and the Red Crab Spider is specialized to live within the Pitcher plant. A specialist specie is one that occupies a narrow niche, while a generalist specie is one that has a broad niche and have the ability to live in different places. An organism cannot exist in isolation because its job must involve other organisms, which leads us to our next discussion in class on relationships within communities.

The Red Crab Spider inside the Pitcher Plant, an example of mutualism.

There are five different types of interactions within a community:

1. Competition (-,-)–Both organisms are hurt because they are both exerting energy.

-Interspecific vs. Intraspecific

2. Predation (+,-)–One organism benefits and the other one dies.

-Carnivory vs. Herbivory

3. Parasitism (+,-)–One organism benefits and the other is hurt, but not killed.

-Two types: External and Internal parasites

4. Commensalism (+,0)–One organism benefits but the other doesn’t, but it’s not harmed either.

-Ex: Certain epiphytes.

5. Mutualism (+,+)–Both organisms benefit.

6. Amensalism (-,0)–This isn’t really a relationship because it is accidental.

-One organism is hurt and the other is unaware. Ex: an elephant stepping on an ant.

http://visitcranelake.com/images/blog/spider%20in%20pitcher%20plant.jpg

The Competitive Exclusion Principle we briefly mentioned at the end of class. It occurs when two species have the same niche and coexist in the same ecosystem. One specie will be excluded from the community due to competition. Three possible outcomes can occur because of this:

1. Both species will suffer (-,-)

2. The weaker specie, or loser, will be forced to migrate or might die.

3. “Job sharing” occurs. Also known as resource partitioning. A species will assume a smaller realized niche because it cannot occupy its complete fundamental niche.

For those who didn’t complete the study guide, a realized niche is a narrow niche which the organism is usually highly adapted to. A fundamental niche is the full range of environmental conditions under which an organism exists, so it’s much broader.

That’s basically everything we covered in class. Feel free to comment if you want or if I missed anything important.