Amazon River Exhales Carbon Dioxide

Amazon River: Credit NASA

Amazon River: Credit NASA

There is a continuous cycle in the rainforest where plants use the carbon dioxide in the air and then produce oxygen. We as humans consume oxygen and produce carbon dioxide.  Thus the Amazon rainforest has earned the nickname the lungs of the earth. Plants use the carbon dioxide to grow branches limbs etc.  Thus when branches break or trees fall carbon is returned back again to the earth.

It was long believed that the carbon then floated down the Amazon River and finally was deposited in the Ocean.  However recent research is showing that the Amazon River is actually “exhaling” carbon dioxide, so much of the carbon isn’t really making it to the Atlantic Ocean. People thought that stems, branches and bark were too tough and couldn’t be digested by the bacteria in the river.  But the new evidence published in Nature Geoscience proves that the woody plant matter is in fact almost completely decomposed by the bacteria of the river.

The newest research shows that only five percent of the carbon from the Amazon Rainforest ever makes it to the ocean.  In fact tough lignin, which is found in woody tissue, was once thought to be buried on the seafloor and remain there for centuries.  Now the latest research shows that it can be broken down in just two weeks if the right bacteria is present.

The research for this study had to take place where the river meets the ocean.  This is quite a treacherous area to study and perhaps this is why it took so long to prove.  The water is so rich in sediment that it is deep brown.  When the tides change the ocean rises by thirty feet and the flow of the water reverses.

The research showed that forty five percent of the lignin broke down in the soil, fifty percent broke down in the river, and the remaining five percent reached the ocean.  Researchers concluded that the runoff of the rain took not only carbon with it, but also bacteria.  And this bacteria is responsible for the continuing breakdown of lignin.