But when the plants die and decay, the carbon combines with oxygen again and returns to warm the atmosphere. All the carbon doesn't return to the air, though, because some organic matter decays very slowly. Vast amounts of carbon are stored, for instance, in northern peatlands. In fact, the peatlands may contain more than half as much carbon as the amount already in the air. Writing recently in Nature , scientists from the University of Wales say the peat decays slowly because it contains chemicals blocking the enzymes that cause decay.
Enzymes are biological catalysts.
Without the right enzyme around, most biochemical reactions go slower than a molasses-covered glacier. But the right enzyme turns the light green and abolishes the speed limit. In the peatlands, it seems, an enzyme called phenol oxidase doesn't do its job of breaking up alcohol-like chemicals called phenols. When phenols accumulate, they block the action of other enzymes that cause decay, the Welsh scientists surmise. Based on lab experiments and measurements in Florida wetlands, the Welsh group concludes that lack of oxygen keeps the phenol oxidase inactive.