PDS APES 5th Period 2009-10

Today during the second half of class, we discussed ozone, or O3.

The first thing to recognize when discussing ozone is that there is good ozone, and there is bad ozone.  You MUST be able to distinguish between the two of these!

Good ozone (O3) is responsible for absorbing and blocking about 95% of harmful UV radiation from the sun in the stratosphere (NOT the troposphere).  Good ozone is what we want to maintain in the stratosphere, obviously.  Without it, humans and plants are exposed to UV-A and UV-B, which penetrate through the skin and cause DNA to lose electrons. This leads to tumors called carcinoma and melanoma.  Without good ozone, we are also at risk of cataracts, severe sunburn, skin cancer, lower crop yields, and less phytoplankton which the food chain depends on.

Bad ozone is a main component of photochemical smog, and obviously we want to minimize the amount of bad ozone that is released into the atmosphere.  Bad ozone irritates the eyes, nose, and lungs, and damages plant’s leaves.

One of the most common misconceptions about ozone is that there is a “hole” in the ozone layer.  In reality, the issue at should be referred to as “ozone thinning.”  The ozone layer varies in thickness and concentration throughout the stratosphere.  Thick is obviously better because it can better protect us from UV radiation.  Here is a diagram showing the varying concentrations of ozone in the stratosphere but NOTE: No where is there a “hole” or complete absence of ozone!!!

NOTE: There are different concentrations of ozone, but there is NO "hole" in the ozone layer, only thinning. Source: http://www.skincancer.org/ozone-and-uv-where-are-we-now.html

The “hole” is the largest or the most thinning occurs during the spring months (September-October) in Antarctic.

CFCs (chlorofluorocarbons) were discovered in 1928, and at first they were considered “the dream chemical” because they were useful and versatile, yet they weren’t explosive or dangerous, or so they thought.  They were used for coolants in refrigerators, propellants in aerosol cans, and in plastic bubble packaging.  But in 1974 research proved a reaction of CFCs in the stratosphere, which was destroying good ozone.  When UV light hits CFCs, the chlorine in the atmosphere is free and reacts with O3 causing these series of reactions:

Cl + O3  –> ClO (unstable) + O2              ClO + O –> O2 + Cl….. then this Chlorine continues to react with O3 creating a vicious cycle where good ozone is being removed from the stratosphere.  Once this discovery was made, a large movement to remove all CFCs from the market quickly began.  Here is a good description of this reaction that takes place in the stratosphere that Mr. Willard sent me (I’m not sure who to credit this??):

A good description of how O3 is destroyed by CFCs in the stratosphere

The Montreal Protocol has been very successful in eliminating CFCs in most products.  Almost every country has signed on to it now, and ozone remediation is working, but slowly.

Since the Montreal Protocol was started, major steps have been taken to reduce the amount of CFCs in products worldwide. Source: http://www.amstat.org/publications/jse/v17n2/nelson.html

On Friday, we talked briefly about water surpluses– otherwise known as flooding.

In class, we discussed two causes of water surpluses.  Flooding is caused by natural events, but is also influenced by human activities.  These causes are explained below:

1. Natural causes- Too much or excessive rain causes the water in rivers to overflow over the river’s banks and into the floodplain.  Examples of these events are hurricanes, thunderstorms, tsunamis, etc.  Although we have seen many cases when floods are extremely destructive (i.e. Hurricane Katrina, 2004 tsunami) but floods can actually be helpful by leaving behind nutrients in the flood plains.  Floods leave land very fertile.

2. Human activities- There are several ways that humans can increase the likelihood and severity of floods.  (1) First off, human pavement causes flooding because rain cannot permeate through asphalt, so the rainwater ends up flowing into rivers. (2) Another human impact is engineering structures such as dams, levees, and floodwalls. Although these structures are built to contain water, they often fail because as water is stored and builds up, its destructive capacity increases tremendously.

This image shows the destruction caused by floods:

After years of steady rain, the Mississippi River basin failed to control the surplus of water causing water to overflow into the surrounding floodplain.

http://ks.water.usgs.gov/pubs/fact-sheets/fs.024-00.miss.flood.jpeg

We didn’t have time to discuss solutions to flooding in class, but there are ways we can prevent and control flood damage, which are found on page 245 of our textbook:

Prevention:

• Preserve forests on watersheds
• Preserve and restore wetlands in floodplains
• Use floodplains primarily for recharging aquifers, sustainable agriculture and forestry

Control:

• Strengthen and deepen stream (channelization)
• Build levees or floodwalls along streams
• Build dams

Okay so I am starting to get a little confused on all the terms that deal with deforestation.  I know the difference between clear-cutting, selection-cutting, and strip-cutting, but I also sort of remember some one saying that it was best to cut down old-growth forests rather than second-growth forest.  This doesn’t seem right to me because old-growth forest have so much more biodiversity and is the habitat for many species.  I might have just made this up…. haha but does anyone know which is the best option: old growth or second-growth or are they just as equally bad for biodiversity and the rest of the environment?

Okay, so I’m studying chapter six right now and I came across the vocab word “biotic potential.”  I have always had a hard time understanding this.  This definition in this book says it is a species capacity for growth.  Is this related to this species carrying capacity??  But it also says in the book, “together biotic potential and environmental resistance determine carrying capacity.”  I don’t really get this in a real life scenario… any help?

and jessica and james- yall should appreciate this post because we could not figure out this before this test and then it was a question!

I’m still confused on winds.  I was looking over my chapter 5 test, and question number 4 describes winds that produce arid climatic regions called deserts.  The answer is Hadley cells, but I am confused because I thought the difference between Hadley and Ferrel winds were that Hadley cells governed the tropics and Ferrel cells governed temperate regions.  Maybe I was wrong about that, but I’m pretty sure it’s right…. Maybe I am just not really understanding these winds.  Any help?

I have one last easy question on my study guide that I couldn’t quite answer.  Number 8 asks why do we use crude birth and death rates instead of the total number?  I know that we use these numbers in our calculations for AGR and such.  Is it simply because they are “nicer” numbers to work with, or is there another reason why we use CDR and CBRs to evaluate population trends?

And if some one could answer Emily’s first question about why there is more growth in cities in developing countries than in developed countries because I was confused on that too.  My guess would be that more people are just swarming to urban areas seeking better health care, sanitation, family planning, education, etc. so their growth is much more rapid but I am not positive.

So I have a similar question to Emily’s.  I understand the difference between macroevolution and microevolution because macroevolution occurs over a much longer period of time, and it is when new species are formed.  But when you say that microevolution occurs over a shorter period of time, what is that estimated time span? Within an individuals life? Years? I know that an individual cannot evolve, and only populations can, but I guess I’m just still a little confused on microevolution and the example that Andy gave in his post… I’m having trouble recalling AP Bio material.  If anyone could try to explain microevolution in another way that would be great! Sorry this is repetitive!

I was absent the day that we talked about the coriolis effect and the Hadley cells, the Ferrel cells, and the Polar cells.  I am looking at the diagrams, and I do not understand the relationship they have between each other.  Maggie’s scribe post said that properties of air, water, and land formed these cells.  If any one could just clarify the differences between these that would be great! And yes I know that it is really late…

First off, Mr. Willard: I’m not quite sure if this counts as a reflection post, but regardless I thought it was interesting and applicable to what we are starting to studying!

Today as I was driving into my neighborhood, I was stopped right in front of my house because my neighbors across the street were doing some construction in their front lawn.  When I looked up though, I saw a tree literally hanging from a crane.  Here are some pictures that I took from my car because it really was a really funny site:

Tree hanging from the crane

Really Big Tree being cut down

Another pic of the tree in mid-air.

I’m not really sure if the pictures do it justice, but this tree was literally in mid-air and it was a really big tree.  I had never seen this process done in this manner before, and I don’t think many others have either because about 10 people were in my backyard watching the process.

As I was stopped in my car waiting for them to move the tree, I started to think about how this relates to exactly what we are starting to talk about in class.   First off, I thought about all the services that it was going to take to cut down these four trees.  They had a giant trucks, 2 bulldozers, a tree shredder, and a crane.  All of these service create a large ecological footprint.  Also, I thought about the positive effects those four trees had to the earth.  They provided oxygen, a habitat for many animals, aesthetic beauty, and many others I’m sure we will learn about this year.  I think this relates to the “A” in the I=PAT equation.  This family had the money obviously to cut down these trees, so they did without thought to the impact the trees had to the earth.  I can’t imagine how much of an impact this makes when thousands of people in our country are doing this daily.  I hope this gets other people in the class thinking about simple acts like these we see daily…

Last night for homework, everyone in the class went to http://www.ecofoot.org/ and found out their personal ecological footprint.  We answered questions about the food we ate, the number of miles spent in our car, the cost of our electricity bills per month, and many other questions.  At the end, the website told us how many planets it would take to support humanity if everyone lived like us, the number of global acres that are needed to support us, and what area of our footprint is the largest.  The results looked something like this:

This is a sample of what our results looked like

Today in class, Mr. Willard put every one’s data into a big table so we could compare our results and find the average.  Here are our results:

Our data!

The first thing that we pointed out after examining our data is that no one, not even Mr. Willard’s lifestyle, would support all of humanity.  The lowest number of earth’s used was 3.9 and most people reported that services were the largest portion of their footprint.  Since our population is growing exponentially, people are beginning to try to find solutions to how we can maintain the earth’s resources.

Before we start getting into solutions though, we need a working definition of an ecological footprint.  An ecological footprint, as defined by our textbook (and revised by Mr. Willard), is an estimate of how much of the earth’s resources an individual (per capita) consumes.  Another definition is the amount of productive land and water needed to support an individual and remove wastes. For example, we said in class that most people do not grow all the food they eat at home, so then they must go to a store like Harris Teeter to get their food.  The process of making the food,  shipping the food by either truck or plane, and driving to get the food from the store is one example of how we expand our footprint from just the area we live in.

The equation I=PAT from Watershed is used to calculate our national footprint.  I=ecological impact or national footprint, P = population, A = affluence, and T = technology.  Technology can be either positive or negative depending on if the country has smart, green technology, or no advanced technology.  **Just because the technology is negative though does not mean that the impact is good!  It just shows that the technology is advanced, but there is still some impact made!**

Here’s an example of the I=PAT equation put to use:

Country X= 100 x 2 x 8 = 1600

Country Y = 50 x 8 x 5 = 2000  This shows that even though Country X has a larger population and not as advanced technology, its affluence causes it to have a larger ecological impact.

We concluded the class period by saying that this discussion isn’t supposed to make us feel guilty about our impact on the earth.  This exercise is used to make us aware of our impact because the earth’s resources are limited!  Our earth’s population is growing exponentially and is expected to reach 9 billion by 2060.  The question is, when will the earth hit its carrying capacity level?  If growth continues to remain unchecked, we could potentially run out of resources within our lifetime!  This is why, like we read in Watershed, people are considered the problem because they use resources and create waste, which take services to manage!  The main point of this activity is to give us a look at what we are going to start studying over the year, and to try to start thinking about what is a more reasonable way that we an live our lives.