In recent years, the amount of nitrogen compounds fixed by human activities has
A)exceeded the amount of nitrogen compounds fixed by natural processes.
B)been reduced to a level below the amounts fixed by natural processes.
C)equaled the amount fixed by natural processes.
D)fluctuated above and below the amounts fixed by natural processes.

Question

Quizplus · Accepted Answer

Human activities such as the use of nitrogen fertilizers and burning of fossil fuels have greatly increased the amount of nitrogen compounds fixed, exceeding the amount fixed by natural processes. This has resulted in nitrogen pollution and other environmental problems.

In Recent Years, the Amount of Nitrogen Compounds Fixed by Human