PDS AP Environmental Science 5th Period 2010-11

Are there any effects of the depletion of stratospheric ozone besides UV radiation causing skin cancer?

Could someone explain to me how each happens in plain English?

Also, what is each used for in the process of making nuclear energy?

How exactly does saltwater mix with aquifers when groundwater is overpumped? Is it from the pressure of pumping the water up or something else and how exactly does it occur?

I know industrial agriculture became big in the 80s, but why did it happen then?

1. Agriculture

• As the book says, we use 38% (small percentage, but not all can be used for farming because of ice and deserts and other areas that aren’t fit for farming)  of the Earth’s surface area for agriculture. (The “most devastating activity to the environment.”) We mostly use the temperate regions for agriculture (prairies and temperate deciduous).
• It takes hundreds to thousands of years to make just 1 inch of soil (depends on the region).
• Agriculture is separated into two categories: crops (cropland) and livestock (rangeland).
• Soil is a potentially renewable resource, which means we need to manage our consumption carefully so we don’t use it faster than it is made.

2. Soil Structure

The different components to soil

Image source: http://www.salinitymanagement.org/Salinity%20Management%20Guide/images/module_ds/ds_illust_2.gif

Soil is.. 45% Water and Air in pores

50% Sand, Silt, and Clay (different sizes). aka Inorganic material.

5% organic material, composed of detritivores, decomposers, and decaying organic matter

• Detritivores break leaves and other matter into smaller parts for the decomposers (which are fungi and bacteria) that break those down into Nitrogen, Phosphorous, and Potassium (NPK), the macronutrients that plants need most.

3. Soil Formation

As we already learned, there are three types of weathering (the “principle agent to soil formation”)

1. Physical–plate tectonics and ice wedging

2. Chemical– H20+CO2–>H2CO3

3. Biological–Roots

This brings large particles to small particles:

Weathering makes larger particles into smaller ones: Sand, then silt, then clay

Image Source:

http://www.yksd.com/distanceedcourses/Courses/PhysicalScience/Lessons/SecondQuarter/Chapter06/Lesson01/Sand_Silt_Clay.gif

Definitions: Soil profile: The cross-section as a whole from surface to bedrock.

Soil Horizon: Each specific layer of soil

There is a handout on Soil Horizons in the box, but if you need another source… (Only layers O, A, E, B, C, and R are on our sheet, so ignore P and D.)

http://en.wikipedia.org/wiki/Soil_horizon#Layers

A few things we said about the different horizons in class:

• If there is too much leaching, all of the NPK ends up at the bedrock (level R).
• Tree roots can only reach to the very top of the zone of accumulation, so if too much of the NPK is leached downwards, the tree roots cannot reach them.
• Level A is what is known as topsoil, which is (hopefully) rich in humus, which is a dark mix of rich nutrients (like potting soil).
• The largest particles are at the bottom and the smallest are at the top
• A, B, and C are what we call dirt
• The O horizon contains decaying matter

Can someone explain bioremediation to me a little better?

The book mentions it really briefly as did Mr. Willard and I don’t think I fully understand it.

All I really know is that its a way to clean up hazardous materials. There was something about bacteria and the Love Canal but I didn’t really understand anything beyond that.

I find the concept of threshold dose a little confusing.

Does it mean when a dose starts to have an effect or when a dose starts to have a visual effect? Because even before a dose has a visual effect it is having some effect it seems like. Could someone explain threshold dose and its definition a little better to me?

Can someone help explain to me why biodiversity is greatest in the middle stage of succession rather than any other stage (especially the late stage)?

Ok. I have two questions.

The first one is with the paradox of enrichment, I know the overshoot comes sooner and is greater, so there’s a greater dieback. Does one animal start dying first and that is what leads to the other dying, or do they die in unison or what?

My other question is that Mr. Willard said that at some point the the population of mooses was at its most unstable…but I didn’t write down what that point was. Would it be the beginning of the overshoot or at the peak or on the downside of the overshoot or something else?

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?