Final answer:
Human activities, such as burning fossil fuels and using artificial fertilizers, have significantly altered the nitrogen cycle, leading to issues like eutrophication and contributing to climate change. The increase in livestock from animal husbandry also impacts the cycle by adding carbon to the atmosphere.
Step-by-step explanation:
Human Impact on the Nitrogen Cycle
Human activities have dramatically altered the global nitrogen cycle through a variety of means. The combustion of fossil fuels releases various nitrogen oxides into the atmosphere, leading to the production of acid rain and contributing to the greenhouse gas effect with gases such as nitrous oxide (N₂O).
This process can cause extensive algae growth that depletes oxygen in water bodies, leading to the death of aquatic fauna. Additionally, animal husbandry and the growing number of livestock contribute to increased atmospheric carbon levels, affecting the biogeochemical cycles further.
Aggressive agricultural practices, involving nitrogen-fixing crops like soybeans and alfalfa, also contribute to nitrogen fixation, which may exceed the natural capacity of the environment to denitrify, further contributing to ecological imbalance.