Why microbes sometimes fail to break down organic carbon in soils

A new study has found that:

In oxygen-starved places such as marshes and in floodplains, microorganisms do not equally break down all of the available organic matter. Instead, carbon compounds that do not provide enough energy to be worthwhile for microorganisms to degrade end up accumulating. This passed-over carbon, however, does not necessarily stay locked away below ground in the long run. Being water soluble, the carbon can seep into nearby oxygen-rich waterways, where microbes readily consume it.

Tests found that, in contrast to the layers where oxygen was available, leftover carbon compounds in the sediment samples where sulfur had been used for respiration instead of oxygen were mostly of the sort that requires more energy to degrade than would be liberated through the degradation itself. Making these carbon compounds of no use, then, to growing microbes, and had remained within the deeper sediment layers.

Shunned by microbes, organic carbon can resist breakdown in underground environments, Stanford scientists say | Stanford School of Earth, Energy & Environmental Sciences

New nitrogen cycle pathway bypasses the greenhouse gas N2O

Nitrous Oxiden_bypass_900

Nitrous oxide is 300 times more effective at trapping heat than carbon dioxide and 10 times more effective than methane. Nitrous oxide also moves into the stratosphere and destroys ozone. Now a new pathway in the nitrogen cycle has been discovered that avoids nitrous oxide production.

Virginia Institute of Marine Science – Researchers discover greenhouse bypass for nitrogen