Accumulation of toxins is known as biological magnification . Nutrient Flow Carbon cycles from organism to organism Carbon dioxide gas is produced by animals and used by plants. Of great concern is that excess carbon dioxide is produced by automobiles and industrial processes and contributes to global warming The nitrogen cycle Nitrogen in the atmosphere is converted into nitrogen compounds and then incorporated into proteins by nitrogen fixing bacteria . Other bacteria take nitrate, a molecule containing nitrogen and oxygen atoms, and convert it into nitrogen gas which is released to the atmosphere, completingn one part of the cycle. Animals break down proteins into nitrogen wastes, like urea, which is excreted in urine, giving it a yellow color.
Humans artifically fix nitrogen to make fertilizer.
The amount of this industrial nitrogen fixation has risen to alarming levels and now is about equal to the amount of nitrogen fixed by natural processes. Global ecological problems which we face in the immediate future Acid Rain Nitrogen compounds such as nitric and nitrous oxide and sulfur compounds such as sulfur dioxide, are converted respectively to nitric acid and sulfuric acid and cause extensive damage to crops and forests. Global Warming Excess carbon dioxide produced by human activity is building up in the atmosphere.