How are humans affecting the phosphorus cycle?
What will be an ideal response?
Answer: The major storage in the phosphorus cycle is in the lithosphere. It is released to soils by rock weathering, taken up by plants, and passed through the biosphere. Phosphorus is released back to soils and water by decomposition of waste and dead biomass. Phosphorus is an essential nutrient for plant growth.
When we harvest crops, the phosphorus they contain is removed from farm fields and this, along with removal in water that runs off the fields, depletes soil phosphorus stocks. We replace this lost phosphorus, and stimulate crop growth, by adding phosphorus fertilizers to the soil. These fertilizers are produced by mining phosphate-rich rock, and by mining accumulations of bird droppings in some coastal and island areas. The addition of large amounts of phosphorus (and other nutrients) to streams, lakes, and coastal areas, has dramatically altered aquatic ecosystems. These additions stimulate the growth of algae and can lead to lake and stream eutrophication and can lead to "dead zones."
To combat these problems, farmers are encouraged to use less fertilizer, or to use techniques that maximize the efficiency of fertilizer use.
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Major volcanic peaks of the Cascade Mountains, like Mt. Rainier, Mt. Shasta, Mt. Hood, and Mt. St. Helens, have been active volcanoes for 30 to 40 million years.
Answer the following statement true (T) or false (F)
Why is ranching more common in the Rocky Mountain region than agriculture?
A) Cattle and sheep can graze in areas with marginal soils and little water. B) Cattle and sheep were more profitable than agriculture. C) The long period of snowfall would affect animals less than plants. D) Ranching is not more common in the Rocky Mountains than agriculture.
Black holes are thought to be abundant, yet they are hard to find. Explain why
What will be an ideal response?
When a number of earthquakes along in the same general area over the course of a few months or years, the event is referred to as a(n) ________ .
A. seismic batch B. tectonic bundling C. earthquake cluster D. faulting episode E. gap buster