Production of Recalcitrant Organic Matter under the Influence of Elevated Carbon Dioxide and Temperature

Abstract

The effects of elevated CO 2 and temperature on the quantity and quality of dissolved organic carbon (DOC) of wetland sediments were investigated by measuring organic matter decomposition rates and phenolic compounds as target recalcitrant organic matter. Mean rates of anaerobic microbial metabolism were consistently higher both in vegetated sediments and in elevated CO 2 and temperature, although the differences were not statistically significant (P , 0.05). Concentrations of phenolic compounds in sediments with vegetation are significantly different (P , 0.05) from those in sediments without vegetation. Regarding the biodegradability of the phenolic compounds, vegetated sediments showed higher concentrations of 2-chlorophenol and 2,4-dimethylphenol under elevated CO 2 and temperature conditions, which means that more refractory material can be produced through enhanced organic matter degradation by elevated CO 2 and temperature. The produced phenolic compounds can be transported to the freshwater ecosystem and influence the recalcitrance of DOC. Water Environ. Res., 86, 779 (2014).

Bacteria and Archaea Regulate Particulate Organic Matter Export in Suspended and Sinking Marine Particle Fractions

“…These molecules are rapidly remineralized by microbes in the surface ocean to produce dissolved inorganic carbon (DIC), thus reducing export efficiencies (the microbial loop) ( 24 , 27 ). Alternatively, prokaryotic-produced recalcitrant dissolved organic carbon (RDOC) (e.g., lignin and lipids) may be exported to the deep ocean, facilitating longer-term storage ( 28 – 30 ). A small percentage of prokaryotic DOC production is refractory (rDOC) (e.g., ~5 to 7% derived from glucose), which resists rapid remineralization and further degradation ( 31 – 34 ).…”

Prokaryotes Regulate Particulate Organic Carbon Export in Suspended and Sinking Particle Fractions

“…Alternatively, recalcitrant DOC (RDOC) (e.g. lignin and lipids) is exported to the deep ocean, and therefore longer-term storage becomes possible [14,15]. A small percentage of microbial DOC production is refractory (rDOC) (e.g.…”