Question

Intro of nitrogen cycle causes and conqunces of the excessive loading

Answer 1

induction

Nitrogen is everywhere! In fact, \text N_2N2​N, start subscript, 2, end subscriptgas makes up about 78% of Earth's atmosphere by volume, far surpassing the \text O_2O2​O, start subscript, 2, end subscript we often think of as "air".^11start superscript, 1, end superscript

But having nitrogen around and being able to make use of it are two different things. Your body, and the bodies of other plants and animals, have no good way to convert \text N_2N2​N, start subscript, 2, end subscript into a usable form. We animals—and our plant compatriots—just don't have the right enzymes to capture, or fix, atmospheric nitrogen.

Still, your \text{DNA}DNAD, N, A and proteins contain quite a bit of nitrogen. Where does that nitrogen come from? In the natural world, it comes from bacteria

bacteria plays a key role in nitrogen cycle

Nitrogen enters the living world by way of bacteria and other single-celled prokaryotes, which convert atmospheric nitrogen—\text N_2N2​N, start subscript, 2, end subscript—into biologically usable forms in a process called nitrogen fixation. Some species of nitrogen-fixing bacteria are free-living in soil or water, while others are beneficial symbionts that live inside of plants.

Answer 2

The ''nitrogen cycle'' is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth's atmosphere (78%) is atmosphere nitrogen,[1] making it the largest source of nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems.

The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the global nitrogen cycle.