PDS APES 8th Period 2009-10

Since our scribe never got this topic posted, here is a link to a good summary of the topic from the other class:

http://pdsblogs.org/pdsapes510/2010/04/22/acid-rain/

Don’t forget indirect effects of acidic soils…just as important as direct damage from acidic precipitation!

*This is a guest post by EmilyO in the other class.  Not sure everyone was there due to APs and not sure those that were there were very focused, so maybe this will be of use…

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!

Today we talked about hydrogen and how it can be used to power vehicles. Of the forty-four free response questions on previous A.P. exams, none have addressed hydrogen power, so Mr. Willard said this would be “good knowledge to have in our pockets.”

First we reviewed what we already knew about hydrogen. Hydrogen is the most abundant element in the universe. Despite this fact, there is almost none in the troposphere, and this is because hydrogen has a very low density and so it rises. Additionally, hydrogen is very unstable, so it likes to bond with things (i.e. with oxygen, thus water).

In a hydrogen-powered car, the traditional internal combustion engine is replaced with a fuel cell. Here is a link to a video we watched in class about how a fuel cell works: How A Fuel Cell Works: Inside A Hydrogen-Powered Car (http://auto.howstuffworks.com/fuel-efficiency/alternative-fuels/dangerous-hydrogen-fuel1.htm)

As with every energy source, there are pros and cons. The pros to a hydrogen-powered car is that water is its only emission, it is a strategy for reducing fossil fuel use, and hydrogen is the most abundant element in the universe. On the flip side, the cons to a hydrogen-powered car are that we have to harvest the hydrogen or “make it” (which requires energy input), since this source of energy is new, the infrastructure for hydrogen power is not there, and that we can’t simply convert petro-gas stations to hydrogen gas stations. Perhaps we can add on to our petro-gas stations, and if we harvest the hydrogen or “make” the hydrogen by generating energy from renewable resources such as wind or solar power, technically the energy is still clean. But if we generate the energy for hydrogen from a coal-based power plant, then we’re just moving the source, but the impact is still the same.

Hydrogen can be “harvested” or “made” from electrolysis (splitting water), from biomass, and from fuel.

The U.S. Government is currently funding research on hydrogen power in the state of California. Hydrogen power is still very much in the research and development stage. Hope this helped!

Below is a picture of a typical hydrogen fuel cell:

http://images.google.com/imgres?imgurl=http://www.che.tamu.edu/groups/Wood/H2%2520movie_files/image003.gif&imgrefurl=http://www.che.tamu.edu/groups/Wood/H2%2520movie.htm&usg=__K3fNnt0v-ftXo11ZxrB83AVzpL0=&h=450&w=450&sz=26&hl=en&start=6&um=1&itbs=1&tbnid=11w-PWqxONm6CM:&tbnh=127&tbnw=127&prev=/images%3Fq%3Dhydrogen%2Bfuel%2Bcell%26um%3D1%26hl%3Den%26sa%3DN%26rlz%3D1R2GGLL_en%26tbs%3Disch:1

Plate Tectonics and the Rock Cycle

http://www.merrittcartographic.co.uk/plate_tectonics.html

The theory of plate tectonics came about in the mid twentieth century after compiling centuries of speculation andcontemporary  oceanographic studies that suggested that the earth’s surface was actually made up of moblie plates of solid rock floating on a sea of liquid hot mantle that flows at a rate of inches per year.  This mantle operates like a convection cell with hotter liquid metal rising towards the surface and denser cool rock sinking down back towards the Earth’s core.  The floating rocks, or plates, each cover immense area on the Earth’s surface and fit together like a 20ish piece puzzle across the globe.  The most interesting part of the theory of plate tectonics is the area where two plates meet, or a plate boundary.  Due to the plate boundaries unstable and mobile nature, volcanoes and earthquake activity cluster around active boundaries, which are sometimes referred to as faults.  The most notorious of these active regions surrounds the Pacific Plate, the largest tectonic plate on Earth, is dubbed the “Ring of Fire”.  This is one of the most highly active areas on the earth and contains a plethura of subduction zones and oceanic trenches that contribute to massive earthquakes and tsunamies, as well as a multitude of active and inactive volcanoes.  The subduction zones, most of which are in the pacific off the coast of asia and North America, create deep abysses and ocean trenches.  The marianas trench, the deepest point on the Earth, is the subduction zone on the Western plate boundary of the Pacific Plate.

Plate tectonic activity

The Rock Cycle

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/boundaries.gif

The rock cycle is constantly in motion across the planet, and keeps recycling rock over eons through natural processes.

https://www.e-education.psu.edu/files/earth530/image/rock_cycle.gif

Mr. Willard said that we should already know about the background about ozone, but here’s a quick glance at what he was talking about:

• Ozone is a “global sunscreen” for the Earth. It blocks  and absorbs 95% of UV radiation!
• The ozone layer is 12 miles or 20 kilometers thick.
• The ozone layer exists in the stratosphere, and is considered “good ozone.”

Good Ozone vs. Bad Ozone:

Bad Ozone (Tropospheric Problem): Ozone (O3) can exist in the troposphere at ground level, but is “bad ozone,” because it can cause lung disease.

Good Ozone (Stratospheric Problem…if there’s a “hole”): The thing about “good ozone” is that it does absorb and block UV radiation. The thinning of the ozone layer, or what we now call the “ozone hole” is really a  dip in the thickness of the ozone layer. This thinning is caused by chloroflourcarbons (CFCs). These CFCs are “dream chemicals” that are odorless, nonflammable, and nontoxic and are used in aerosol cans, cleaning agents and coolants. When the UV radiation hits the CFCs, the following reaction breaks down the ozone into toxic chlorine (Cl) and diatomic oxygen. This cycle can be repeated thousands of times and this is the reason the ozone layer is being destroyed so quickly.

Cl + O3–>ClO + O2

ClO + O–> Cl + O2

Unfortunately, the thinning of the ozone layer has caused more UV radiation to penetrate the ozone layer. (The “hole” is largest during the Antarctic spring [September-October.]) This  UV radiation comes in two forms: UV A and UV B which both can cause cataracts and skin cancer in humans (UV A rays have wavelengths deep enough to cause squamous cell carcinoma in humans, and UV B rays have wavelengths shallow enough to cause melanoma),  damage DNA in animals and plants, reduce phytoplankton, and reduce crop yields.

Squamous Cell Carcinoma

Melanoma

In the 1980′s, scientists began observing the ozone layer, and in response to the “hole” observed near Antarctica and Europe, the international community came together a created the Montreal Protocol. This was designed to protect the ozone layer by reducing the CFC output by 1/3 by 2000 and bring back ozone levels to 1950 levels by 2100.

Ozone Levels 1980-1991

We always hear a lot about “Global Warming” or “Global Climate Change,” but is there even any solid evidence to back it up? The truth is that, even though the idea that global climate is changing at an unnatural rate because of human activities is still not 100% proven to be fact, there have been a lot of scientific observations that make it fairly obvious that we’re having at least some effect on the global climate. In class on Tuesday, we discussed this evidence of an unnatural increase in global climate and the possible effects it could have.

http://shewonk.wordpress.com/2010/02/14/a-ghcn-analysis/

By looking at this graph of the level of the temperature anomaly over the past 140 years, one can see how the earth has now reached record temperature levels. In fact, the first decade of the 21st century has been the warmest on record.

More evidence supporting the theory of global climate change can be found in the downtrend of the average thickness of glaciers and polar ice caps. Glaciers that exist high on the peaks of mountains and in other cold areas the world over have been shrinking at record rates, further suggesting that the global climate is increasing substantially. In South America and Asia, this loss has been particularly rapid and could threaten the water supply for millions of people. Also, the apparent increase in global climate has led to what seems to be a substantial decrease in the size of polar ice caps. Since 1970, it’s projected that 10 % of Arctic ice cover has been lost. Even though the melting of Arctic ice caps wouldn’t cause he sea level to rise because it’s already in the ocean, the melting of huge inland glaciers like in Greenland and Antarctica could very likely cause substantial increase in ocean levels, devastating coastal cities and coastal freshwater aquifers in the process. Finally, this loss of ice and snow cover can lead to a positive feedback loop in which the problem adds to itself in making the effects of climate change worse.  Since snow and ice have higher albedos than water and soil, they reflect more heat energy from the sun and keep the earth cooler as a whole. With glaciers and ice caps melting, more heat absorbent water and soil is being left behind, merely exacerbating the effects of global climate change.

http://www.everything-ice.com/images/LOW-E-Albedo-Chart.jpg (A chart that shows the reflectivity of substances due to the albedo effect)

http://shewonk.wordpress.com/2010/02/14/a-ghcn-analysis/

More evidence supporting unnatural climate change lies in the cold tundra and taiga biomes the world over. In these areas,  the frozen layer of soil known as permafrost that lies over 1 meter under the surface has begun to thaw for the first time in about 11,000 years, both reducing these biomes into muddy marshes (or thermokast ponds) that the wildlife isn’t adapted to living in and releasing loads of methane gas that have been trapped in the frozen soil. Methane gas is the most potent primary greenhouse gas next to nitrous oxide with a warming potential that is 23 times that of carbon dioxide.  Thus, as permafrost melts and methane is released, it seems that the rate of global climate change will continue to increase as well.

Lastly, increased acidity of the world’s oceans has been observed, most likely as a result of the increased level of carbon dioxide in the air from human activities. As the temperature and acidity of the earth’s oceans rise as an apparent result of global climate change, the ocean could stop being a suitable habitat for organisms with calcium shells and coral reefs could be destroyed as a result of “bleaching.”

Global climate change is a touchy subject due to its recent entanglement with politics. But politics aside, we can all look at the data report from the IPCC and agree that in the last 150 years our global climate has been growing increasingly warmer. Whether this warming is cause by anthropogenic actions is another story, but erring on the side of caution, since the precautionary principle is always the safest bet, lets assume that global warming is certain and is a result to human causes. The next question is, what can we/should we do? There are two basic strategies
1) Reducing the emissions of green house gases, primarily CO2, as it is in the greatest quantity and is the greatest cause of unnatural warming.
2) Reduce CO2 already in the Atmosphere.
Strategy #1 can be achieved through a variety of different methods such as, “Cap and Trade” (with international cooperation), using LEED enginering to constuct more effienct building and machines, reducing dependancy on fossil fuels, moving to renewable energy resources, using alternative fuels for vehicles such as hydrogen, and stoping the consumption of meat. Strategy #2 involves the sequestration (caturing) of CO2 and possibly other green house gases. CO2 can be catured through either natural processes and stored in the biomass of trees and grasses or by man designed means and possibly stored in underground unmineable coal seams. Another solutions is the possibility of liquefying the CO2 and injecting it into the sea floor, but this presents the problem or raising the acidity of ocean water.

*Note: Yet another guest post from Kevin H. in the other class as I forgot to ask for a scribe!

At the end of class on Friday Mr Willard left us with 5 questions regarding global climate change. These questions were as follows:

1. Is the Earth warming?

2. If so, is this warming unnatural?

3. If it is unnatural, is it anthropogenic (human-caused)?

4. What might happen as a result of this climate change?

5. What can and should we do to fix this?

Then in class on Monday we discussed the views of the Intergovernmental Panel on Climate Change (IPCC) on this subject and tried to answer some of these questions. So is the Earth warming? According to the IPCC yes, the global average temperature has increased by 0.74 degrees Celsius, which is approximately1.3 degrees Fahrenheit, over the past 100 years. This may not seem like a drastic change but this number is only a global average. It is important to note that in some places the climate is changing very little and in other there is a much more rapid climate shift. For example arctic temperatures have risen twice as fast as the rest of the world over the past 50 years. Another fact that is evidence of global warming is the temperature records as of recent. Since 1861, when temperatures were first recorded, the 5 hottest year are record were 2005, 1998, 2002, 2003, and 2006.

Ok so there is definitely evidence supporting that the Earth is warming, but is this warming unnatural? According to the IPCC temperature and carbon dioxide levels in the troposphere are “beyond normal range” and paleoclimatic records show an “unnatural increase in temperature and carbon dioxide over the past 50 years”. This graph illustrates Carbon Dioxide levels in the atmosphere and Global Temperature over the past 1000 years.

The next question regarding global warming is, Is this unnatural climate change our fault? Once again the IPCC says that global climate change is indeed anthropogenic. Since the Industrial Revolution there has been a drastic increase in 3 of the 4 major greenhouse gases, and these are Carbon Dioxide (CO2), Nitrous Oxide (N2O), and Methane gas. All of these gases have increased due to human activity. The main causes of CO2 increase is the burning of fossil fuels and land use change. Land use change in this situation most directly means deforestation. Deforestation is a major problem because it destroys one of the planets natural carbon sinks. A carbon sink is is a place that stores carbon such as CO2. When you cut trees that usually store carbon more carbon in the form of CO2 is released into the atmosphere. Another acticity that we as humans do to cause an increase in greenhouse gases is agriculture, and this causes increases in methane and N2O levels in the atmosphere.

*Note: This is a guest blog post by Coco in 5th period since I forgot to name a scribe.

Last Friday, we discussed the origins of global warming. However, climate change is a more accurate term since some regions are cooling, not warming.

First off, it must be established that not all greenhouse gases, like water vapor, CO2, CH4 and N2O are “bad.” In fact, without the natural greenhouse effect earth would be very cold, thus uninhabitable, but the natural greenhouse effect makes the Earth warm enough to sustain life. Essentially, when solar radiation reaches Earth’s surface, some is absorbed by land and water, but a good portion is reflect as infrared radiation. Greenhouse gases trap IR, causing warming in the troposphere. Take a look at this diagram:

http://www.ncrlc.com/01-GCC_imgs/figure03.jpg

However, there are several anthropogenic, or human-caused increases in greenhouse gases, such as fossil fuel use, deforestation, and agriculture. This “unnatural greenhouse effect” contributes to global warming, whose effects include but aren’t limited to an increase in average temp, glacier retreats, and severe weather events like hurricanes due to higher ocean temps. However, global warming gets political when people feel forced to relinquish their Hummers on the bases of hypothetical “what if” situations surrounding global warming, such as rising sea levels and their resulting population shifts. So when did all the hype about anthropogenic causes of climate change begin?

Origins of Climate Change:

It’s important to note that Al Gore didn’t invent “Global Warming.” In reality, research on the relationship between increased CO2 levels from the Industrial Revolution and higher temperatures began in 1896 by chemist Svante A. Arrhenius. For more on the history of climate change research, see http://www.npr.org/templates/story/story.php?storyId=10307560.

One important chemist, Charles Keeling, is known for his study of temperature and CO2. His results yielded the Keeling Curve, which “launched the current debate over what to do about rising greenhouse gas levels.”

http://sio.ucsd.edu/keeling/images/Keeling_Curve.jpg

Today, research illustrates with near certainty that average temperatures in the troposphere are increasing. But as for the debate over whether climate change exceeds the natural cycle of warming and cooling, or if human activity is causing climate change, many argue that more research is needed before any decisive conclusions are formed. As with all scientific questions, the question of why the Earth is warming falls somewhere on the spectrum of certainty. In order of least to greatest certainty are: hypothesis, theory, and finally law. With increased data and observation, a hypothesis can either be supported or refuted.

Your car breathes in from the air and the fuel tank and it breathes primary pollutants out, which then are converted into secondary pollutants. The central reaction in your car starts with the reactants in the air (78% N2, 21% O2), and the fuel tank feeds fuel to the engine.

However, the reactions in your car are not this simple, so there are many primary pollutants that come out of your car–some non-regulated (CO2, H2O, N2) and some regulated (CO, NOx, HC/hydrocarbons/VOC/Volatile Organic Compounds, SPM/Suspended Particulate Matter/Smoke) as shown in the diagram below. The important thing to note about NOx is that it is a precursor to O3. When NO2 reacts with sunlight, it forms NO+O. Then O goes on to react with O2 to form ground-level ozone, which is harmful to human’s lungs and plants.

Photochemical Smog (Secondary Pollutant) Formation

The secondary pollutants are produced from a further reaction of primary pollutants emitted from the car’s exhaust, including photochemical smog which was mentioned above. There are two types of smog, outlined below:

Mr. Willard's outline of two types of smog. This lesson focuses on photochemical smog.

Notice the difference in color between the Photochemical Smog on the left produced from car emissions and the Coal/Industrial Smog on the right.

Smog in Los Angeles

Smog in China

_____________________________________________________________