Jun 9, 2016 · In general, human activity releases nitrogen into the environment by two main means: combustion of fossil fuels and use of nitrogen-containing fertilizers in agriculture.

The nitrogen cycle is a crucial process that converts atmospheric nitrogen into a form that plants and other organisms can use. This process, known as nitrogen fixation, is primarily carried out …

Review your understanding of the nitrogen cycle in this free article aligned to AP standards.

This simplified diagram of the nitrogen cycle shows how processes such as nitrogen fixation, ammonification, nitrification, and denitrification move nitrogen from the atmosphere through …

There are two main processes by which human activities release nitrogen into the environment: the combustion of fossil fuels and the use of artificial fertilizers in agriculture.

This simplified diagram of the carbon cycle shows how processes such as photosynthesis, cellular respiration, decomposition, and fossil fuel combustion move carbon between inorganic and …

Nitrogen-metabolizing prokaryotes include nitrogen fixers, nitrifiers, and denitrifiers. They play key roles in the nitrogen cycle by converting nitrogen compounds from one chemical form to another.

Biogeochemical cycles are nature's way of recycling essential elements for life, like water, carbon, nitrogen, and phosphorus. These cycles circulate these molecules through ecosystems and …

People fix nitrogen by burning oil or gas to synthesize ammonia from atmospheric nitrogen and hydrogen. For example, synthetic ammonia fertilizers made by burning fossil fuels contribute …

These include carbon, nitrogen, phosphorus, and sulfur. In particular, surface runoff helps move elements from terrestrial, land-based, to aquatic ecosystems. We'll take a closer look at how …