TY - JOUR T1 - Carbon inputs from riparian vegetation limit oxidation of physically-bound organic carbon via biochemical and thermodynamic processes JF - bioRxiv DO - 10.1101/105486 SP - 105486 AU - Emily B. Graham AU - Malak Tfaily M. AU - Alex R. Crump AU - Amy E. Goldman AU - Evan Arntzen AU - Elvira Romero AU - C. Tom Resch AU - David W. Kennedy AU - James C. Stegen Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/05/25/105486.abstract N2 - In light of increasing terrestrial carbon (C) transport across aquatic boundaries, the mechanisms governing organic carbon (OC) oxidation along terrestrial-aquatic interfaces are crucial to future climate predictions. Here, we investigate the biochemistry, metabolic pathways, and thermodynamics corresponding to OC oxidation in the Columbia River corridor using ultra-high resolution C characterization. We leverage natural vegetative differences to encompass variation in terrestrial C inputs. Our results suggest that decreases in terrestrial C deposition associated with diminished riparian vegetation induce oxidation of physically-bound OC. We also find that contrasting metabolic pathways oxidize OC in the presence and absence of vegetation and—in direct conflict with the ‘priming’ concept—that inputs of water-soluble and thermodynamically favorable terrestrial OC protects bound-OC from oxidation. In both environments, the most thermodynamically favorable compounds appear to be preferentially oxidized regardless of which OC pool microbiomes metabolize. In turn, we suggest that the extent of riparian vegetation causes sediment microbiomes to locally adapt to oxidize a particular pool of OC, but that common thermodynamic principles govern the oxidation of each pool (e.g., water-soluble or physically-bound). Finally, we propose a mechanistic conceptualization of OC oxidation along terrestrial-aquatic interfaces that can be used to model heterogeneous patterns of OC loss under changing land cover distributions.Key pointsRiparian vegetation protects bound-OC stocksBiochemical and metabolic OC oxidation processes vary with vegetationCommon thermodynamic principles underlie OC oxidation regardless of vegetation ER -