Ap Bio Frq Matter Continuously Cycles
1. By: Brian Palm, Catholic Memorial School, West Roxbury, MA
A.B. Dartmouth College, Hanover, NH
MSc Oxford University, UK
Phosphorus mining provides humans with an important product called ammonium phosphate. This key ingredient is used as a fertilizer that helps to increase crop yields in our agricultural system. Ammonium phosphate is derived from calcium phosphate rock that is strip-mined and pulverized on several U.S. states. Producers extract the calcium phosphate and then add sulfuric acid to form phosphoric acid which is later modified to produce the desired product, ammonium phosphate.
As an unfortunate by-product of this process, phosphogypsum is produced. In fact, five tons of phosphogypsum are produced for every ton of ammonium phosphate. The runoff from the phosphogypsum has a pH between 1 and 2.
Florida generates 75% of the ammonium phosphate used by U.S. farmers each year. It currently has one billion tons of phosphogypsum stored at 25 sites around the state, and miners are adding 30 million tons of phosphogypsum to those piles each year.
(a) Using the information above, what is the annual demand of ammonium phosphate by U.S. farmers?
(b) If the U.S. comprises 20% of the world's production, how much ammonium phosphate is produced globally?
(c) Based on this world total, how much of the toxin phosphogypsum is produced on an annual basis?
(d) Identify and describe TWO environmental consequences that result from the extraction/processing of phosphorus.
(e) Describe ONE strategy to mitigate the environmental damage caused by extraction or processing.
(f) Describe ONE alternative strategy that might reduce the need for phosphorus mining.
Correct Answer:
10 Total Points Possible
(a) Maximum 1 point total: 1 point for the correct answer, which must show the correct setup.
Using the information above, what is the annual demand of ammonium phosphate by U.S. farmers?
The annual demand is calculated by using the annual production values from Florida to determine the total U.S. production. Since 30 million tons are produced in Florida AND because 75% of the U.S. total comes from Florida, 40 million tons are produced annually. This is because 30 represents 75% of 40. A range of calculation setups are possible. The correct answer is 40 million tons.
(b) Maximum 1 point total: 1 point for the correct answer, which must show the correct setup.
If the U.S. comprises 20% of the world's production, how much ammonium phosphate is produced globally?
Since the United States produces 20% of the world total, the correct answer is derived by multiplying 40 million by 5, yielding a correct answer of 200 million tons.
(c) Maximum 2 points total: 1 point for the correct setup and 1 point for the correct answer.
Based on this world total, how much of the toxin phosphogypsum is produced on an annual basis?
The following setup is suggested, though inclusion of units is not required. The correct answer can be displayed in the following formats: 1 billion tons, 1,000 million tons, 1 × 109 tons.
(d) Maximum 4 points total: 1 point for identifying each environmental consequence (2 points) and 1 point for describing each environmental consequence (2 points).
Identify and describe TWO environmental consequences that result from the extraction/processing of phosphorus.
The low-pH runoff that results from phosphogypsum was identified in the question's background information. Responses may include environmental consequences that result from acid mine drainage, such as low-pH or the acidification of aquatic ecosystems adjacent to the mines/processing facilities. Habitat destruction or the direct consequences of acidic environments will result in species loss or reductions in biodiversity.
Strip mining is one of the more impactful types of mining in terms of habitat destruction as vegetation and soils are removed entirely to access the resources below.
The use of large mining vehicles produces a range of air pollutants that can also be connected to environmental impacts. CO2 additions will cause climate change, which would consequently result in species decline and habitat destruction. Particulates from Earth-moving activities and/or the particulates released from fossil fuel consumption of the mining equipment may reduce the photosynthetic capabilities of adjacent plant life.
(e) Maximum 1 point total: 1 point for describing the mitigation strategy.
Describe ONE strategy to mitigate the environmental damage caused by extraction or processing.
A range of mitigation strategies are acceptable. Bioremediation is often used in this type of situation where toxin-tolerant plants are used to absorb and take up toxins from the soil or surrounding water bodies. Certain bacteria may also be used to convert some of the harmful toxins, turning them into more benign products. Photoremediation is also used in a process where light is used to break down toxins. Topsoil from other areas might also be brought in to recreate a soil system that can support plant life, helping to stabilize disturbed soil.
(f) Maximum 1 point total: 1 point for describing the alternative strategy.
Describe ONE alternative strategy that might reduce the need for phosphorus mining.
Credit can be earned for describing any strategies that reduce the demand/need for phosphorus fertilizers. This can include suggesting alternatives such as organic fertilizer substitutes; the use of sustainable farming practices, such as crop rotation that utilizes other crops; natural replenishment (through composting or something similar); or using crops that demand less phosphorus (genetically modified crops are acceptable).
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Source: https://www.crackap.com/ap/environmental-science/frq-test5.html
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