Total organic carbon (TOC) is the carbon (C) stored in soil organic matter (SOM). Organic carbon (OC) enters the soil through the decomposition of plant and animal residues, root exudates, living and dead microorganisms, and soil biota. SOM is the organic fraction of soil exclusive of nondecomposed plant and animal residues. Nevertheless, most analytical methods do not distinguish between decom...

The chemical structure of organic matter has been shown to be only marginally important for its decomposability by microorganisms. The question of why organic matter does accumulate in the face of powerful microbial degraders is thus key for understanding terrestrial carbon and nitrogen cycling. Here we demonstrate, based on an individual-based microbial community model, that social dynamics am...

Turnover of deep organic carbon in cultivated soils: an estimate from a review of isotope data Description of the subject. This study is an estimate of medium-term renewal (decades) of deep carbon in cultivated soils. Objectives. Sequestration of organic carbon in soils is a way to mitigate the global rise in CO2 and warming. Deep horizons (> 30 cm) contain about half of the soil organic carbon...

Particulate organic matter (POM) is an important source of energy in aquatic systems, where decomposition rates have traditionally been studied using the litter-bag technique. However, this method has limitations for estimating in situ decomposition rates, especially for fine particles. In this study the litter-bag technique is combined with measurements of microbial enzyme activities to estima...

Marine dissolved organic matter (DOM) is one of the largest reservoirs of reduced carbon on Earth. In the dark ocean (>200 m), most of this carbon is refractory DOM. This refractory DOM, largely produced during microbial mineralization of organic matter, includes humic-like substances generated in situ and detectable by fluorescence spectroscopy. Here we show two ubiquitous humic-like fluoropho...

Due to the widespread pollution of coastal groundwaters with fertilizers, submarine groundwater discharge (SGD) is often thought be a large dissolved inorganic nitrogen (DIN) source ocean. Whether this N autochthonous or allochthonous subterranean estuary (STE), availability quantities DIN can nevertheless interact cycling other elements, such as carbon (C). In previous studies, we documented f...

Marine dissolved organic matter (DOM) is one of the largest reservoirs of reduced carbon on Earth. In the dark ocean (4200m), most of this carbon is refractory DOM. This refractory DOM, largely produced during microbial mineralization of organic matter, includes humic-like substances generated in situ and detectable by fluorescence spectroscopy. Here we show two ubiquitous humic-like fluorophor...

Organic matter dynamics were studied in five streams at Coweeta Hydrologic Laboratory. Three of these streams drained logged watersheds, and two drained reference deciduous forest watersheds. Litter inputs to the streams draining disturbed watersheds were significantly lower than to reference streams. Additionally, while undisturbed litterfall consisted primarily of relatively refractory leaf s...