PDS AP Environmental Science 5th Period 2010-11

As we approach the final day before the AP exam, have you reviewed the nutrient cycles? Knowledge of these cycles is critical-they tie everything together.  In the fall we learned primary reservoirs, key chemical reactions, and anthropogenic impacts.  I also had each of you write a creative short-story of a cycle.  Here is a good one by JoeY:

Being a nitrogen in a nitrate ion was getting boring, especially as I drifted through the sea. I needed to get as far away from here as possible. One day, as I am minding my own business, a denitrifying bacteria comes up to me and asks, “ Want a little adventure in your life?” I couldn’t say no to a ticket out of here. Suddenly, I am pulled away from my oxygen parts, and I start floating up into the clouds. What a view! The atmosphere was so high up that I could see everything! And I also met many of my fellow nitrogen molecules. I started drifting back down to see land beneath me. Then, as soon as I was close enough to a legume, a nitrogen-fixing bacteria takes me in and fixes me up with some hydrogen ions. But as soon as this happened, a plant sucks me into its roots. I stayed in the plant for a while, but when the plant died, I was decomposed and returned to the soil. When I was in the soil, I went through a similar process and became ammonium. But I met some new bacteria friends that converted me into a nitrite ion. Then, another bacteria transformed me back into just nitrogen, and I floated back into the atmosphere. But my time in the air didn’t last long. I was fixed into ammonium again, but this time, I was in the ocean. Some nitrifying bacteria turned me into a nitrite ion. Then I was immediately turned into a nitrate ion. What an adventure!
So, do you remember the steps of the nitrogen cycle? Do you remember the formulas for these forms of nitrogen? Do you recall all the ways humans alter this cycle?

This last chapter, we really started to get an idea of how biogeochemical cycles work and can “malfunction.” Here are a few interesting current events on the topic if you want to learn more:

Nitrogen Cycle: Whales Help Fertilize Ocean With Floating Dung
http://www.npr.org/templates/story/story.php?storyId=130437080

Phosphorus Cycle: Manure, Fertilizer Part Of Chesapeake’s Problem
http://www.npr.org/templates/story/story.php?storyId=121565792

Carbon Cycle: Methane Causes Vicious Cycle In Global Warming
http://www.npr.org/templates/story/story.php?storyId=122638800

and..while we did not focus on the sulfur cycle, this is a good story about the role of sulfur dioxide in our atmosphere:

Sulfur Cycle: With Lave, Volcano Spews Chemicals to Cool Earth
http://www.npr.org/2010/11/12/131276631/with-lava-volcano-spews-chemicals-to-cool-earth?sc=17&f=1007

unfortunately, sulfur dioxide combines with water to form acid rain too…more on this in the spring.

I know that GPP and NPP are used to power the organisms own metabolism through cellular respiration and photosynthesis, but is the only differences between the two is that GPP is the energy resulting from autotrophs powering their own metabolism and NPP is the energy and biomass remaining after autotrophs power their own metabolism?

I know that the good majority of nitrogen is fixed by bacteria, but for the nitrogen that gets fixed by lightning, is it the same reaction as with bacteria or are the formulas different?

What is the difference between dynamic equilibrium and homeostasis because I know that they both are balanced out and stable.

Does the ocean-atmosphere exchange occur primarily by respiration of aquatic life, and does rain also contribute to carbon in the ocean? How does carbon go from the ocean to the atmosphere?

According to the diagram, the only way carbon is released from the sedimentary rock is through volcanic and hydrothermal emissions. Why does the diagram not include uplift or erosion? Are they not important in the cycle?

So I know the primary steps of a fish kill are an increase in nitrogen or phosphorous and that leads to an algal bloom, but what happens after that? basically how does the algal bloom lead to less dissolved oxygen?

What equation is involved when nitrogen enters the soil via decomposition?

So most of the nitrogen is held in the atmosphere as N2. To be put in the soil/ocean the N2 needs to be fixed. Can plants use this fixed nitrogen or does it also have to be nitrified?