Humans Add About 150,000,000 Tons of Fixed Nitrogen to the Biosphere

question 85

Multiple Choice

Humans add about 150,000,000 tons of fixed nitrogen to the biosphere each year, primarily:

• A)through the use of fertilizer.
• B)as nitrogen emissions from burning fossil fuels.
• C)through the nonagricultural use of ammonia.
• D)as nitrogen emissions from industry.
• E)None of the answer options is correct.