大象传媒

Nitrogen is the most common element in the atmosphere. Plants can’t grow without it. Carbon is essential to life: 18 percent of a human body and 50 percent of a tree is carbon. Left alone, natural systems maintain cycles that keep these elements circulating where they’re needed and in the right amounts. But we’ve pulled nitrogen out of the air to feed plants and put carbon, from burning coal and oil, into the air. We’ve thrown natural cycles out of balance. Excess carbon is heating the planet. Excess nitrogen is poisoning the air and water. In order to have the clean water, healthy ecosystems, and stable climate we need to survive, we’ll have to stop overloading the systems.

(1) Humans capture N2 from the air and produce 131 million tonnes (144 million tons) of nitrogen fertilizer each year globally. This adds more nitrogen to the planet than ecosystems would use under natural conditions, busting the Earth’s nitrogen budget.

(2). There are now more than in coastal waters, largely caused by nitrogen pollution.

(3) Both fossil-fuel burning and agriculture also send —as N2O, another powerful greenhouse gas, and NO, a precursor to smog and acid rain.

(4) If we recycled waste (both animal manure and human waste) and used it as fertilizer, we could feed the world with the nitrogen nature produces. If we converted to renewable energy and organic agriculture, we could stop polluting the planet with excess nitrogen. .