Nitrogen-based fertilizers break down into nitrates. when the nitrates enter the substrate, they are converted into nitrogen gas through which process?

The right answer is Denitrification.

Denitrification is a microbial process of alternative respiration. This biological phenomenon is operated by specific bacteria, satisfying their need for oxygen in hypoxic or anoxic soil, by a deoxygenation of nitrate ions. This phenomenon occurs in the soil, but not exclusively: it is also at work in certain sediments, in aquifers (to a certain extent and under certain conditions), in decaying organic matter (eg dead wood), or in the digestive system.

the "dirty dozen" chemicals banned in an international treaty are formally known as persistent organic pollutants, or pops. the united nations environment program provided this background on what they are and what they can do to humans and wildlife.

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