As we saw in chapter 3, nitrogen (N2) makes up 79% of the atmosphere. All life, like proteins, requires nitrogen compounds to survive. However, they can't generally use nitrogen in the gaseous form.

To be used by an organism, nitrogen must be combined with hydrogen and oxygen. Nitrogen is taken out of the atmosphere by lightning or nitrogen-fixing bacteria. During storms, large amounts of nitrogen are oxidized by lightning and mixed with water (rain). This falls and is converted into nitrates. Plants take up nitrates to form proteins.

Plants are consumed by herbivores or carnivores. When these die (organic matter), the nitrogen compounds are broken down into ammonia. Ammonia can be taken up by plants again, dissolved by water, or remain in the soil to be converted to nitrates (nitrification). Nitrates stored in soil can end up in rivers and

Fig. 11-2 The nitrogen cycle is essential to all living systems.

lakes through runoff. They can also be changed into free nitrogen and returned to the atmosphere. Fig. 11-2 gives you an idea of the nitrogen cycle.

As we saw in Chapter 8, extra nitrogen in water (from fertilizers and other runoff chemicals) can lead to eutrophication. High nitrate levels, along with phosphate, can cause the overgrowth of aquatic plants and algae, causing high dissolved oxygen consumption, killing fish and other aquatic organisms.

Survival Basics

Survival Basics

This is common knowledge that disaster is everywhere. Its in the streets, its inside your campuses, and it can even be found inside your home. The question is not whether we are safe because no one is really THAT secure anymore but whether we can do something to lessen the odds of ever becoming a victim.

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  • zufan
    Is global warmings is caused by nitrates?
    19 days ago

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