Organic Carbon Composition and Oxygen Metabolism across a Gradient of Seasonally Inundated Limesink and Riparian Wetlands in the Southeast Coastal Plain, USA

摘要: A set of three relatively pristine seasonally inundated limesink wetlands and one riparian wetland was studied over a 4–6 month long inundation period in 2001. Patterns organic matter properties oxygen consumption the water column followed previously documented ecological gradient based on soil composition, vegetation type, canopy cover. The full canopy, cypress-gum swamp had highest mean concentrations dissolved carbon (DOC; 26.2 mg/l) lignin (sum 6; 299 μg/l) with lower observed partial cypress savanna (22.0 mg/l DOC; 252 μg/l sum 6) open marsh (20.6 135 6), respectively. During period, DOC increased concentration, decreased, δ13C shifted to more positive values which collectively indicate large reduction percentage aromatic during period. All very high matter, yet microbial almost always stimulated by addition glucose rather than inorganic nutrients. Stimulation suggests that there were small pools highly bioavailable forms wetlands. larger pool moderately capacity sustain rates under dark conditions for at least 15 d. lowest average whole (1.0 μM/h) increasing (1.3 μM/h), (1.6 (1.9 compositional fingerprint varied across wetlands, useful identifying different sources vascular plant-derived DOM. Vascular plant production, algal respiration, UV degradation are all important drivers DOM cycling, consistencies this initial assessment suggest they vary predictable ways gradient.