Key question 5

Describe ONE way in which humans alter the Nitrogen cycle

Fertilizer use

What is a major source of phosphorus-rich runoff and what happens to water bodies when this occurs? (describe eutrophication)

High concentrations of phosphorus may result from poor agricultural practices, runoff from urban areas and lawns, leaking septic systems or discharges from sewage treatment plants.

Describe ONE way in which humans alter the Sulfur cycle

Human activities have affected the sulfur cycle primarily by releasing large amounts of sulfur dioxide into the atmosphere.

What is the difference between nitrogen fixation and denitrification?

Nitrogen fixation converts nitrogen gas into ammonia, but denitrification converts nitrates into nitrogen gas.

What is residence time?

the average length of time during which a substance, a portion of material, or an object is in a given location or condition, such as adsorption or suspension.

What is carbon sequestration? Why is it important to research?

Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide. It is one method of reducing the amount of carbon dioxide in the atmosphere with the goal of reducing global climate change. The USGS is conducting assessments on two major types of carbon sequestration: geologic and biologic.

What are the major impacts of acid rain

Dead or dying trees are a common sight in areas effected by acid rain. Acid rain leaches aluminum from the soil. That aluminum may be harmful to plants as well as animals. Acid rain also removes minerals and nutrients from the soil that trees need to grow.

Describe ONE way in which humans alter the Carbon cycle

Humans are increasingly burning fossil fuels, consequently there are more carbon dioxide emissions.

Describe the ways in which humans alter the Phosphorus cycle

Humans have greatly influenced the phosphorus cycle. It has been mined by them, converted into fertilizers, and transported around the world.

Describe ONE way in which humans alter the hydrologic cycle

Irrigation, ground water, pollution