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We employed two compelling and distinct methods, Fourier Transform Infrared Spectroscopy (FTIR) and Ramped Pyrolysis Oxidation (Ramped PyrOx), to examine the quality of organic matter (OM) stored in four peatlands located along a latitudinal gradient (Tropical (4˚N), Subtropical (27˚N), Boreal (48˚N), and Polar (68˚N)). FTIR was used to quantify the relative abundance of carbohydrates, a relatively labile compound class, and aromatics, which are more recalcitrant, in a sample set of four peat cores. These samples were then prepared using Ramped PyrOx, a second, independent method of determining OM quality that mimics the natural diagenetic maturation of OM that would take place over long timescales. Previous large-scale studies using FTIR to evaluate OM quality have observed that it generally increases with increasing latitude (more carbohydrates, less aromatics). Here, we demonstrate that the Ramped PyrOx approach both validates and complements the FTIR approach. The data stemming from each Ramped PyrOx preparation was input to a model that generates an estimated probability density function of the activation energy (E) required to break the C bonds in the sample. We separated these functions into three fractions (“lowE,” “mediumE,” and “highE”) to create Ramped PyrOx variables that could be quantitatively compared to the compound class abundance data from FTIR. In assessing the agreement between the two methods, we found three significant relationships between Ramped PyrOx and FTIR variables. LowEfractions and carbohydrate content were positively correlated (R²= 0.51) while lowEfractions were negatively correlated with aromatic content (R²= 0.58). MediumEfractions were found to be positively correlated with aromatics (R²= 0.69). 

Abstract Geological sources of methane (CH₄), such as hydrocarbon seeps, are significant yet poorly constrained sources of CH₄to seawater and the overlying atmosphere_.We investigate the radiocarbon content (¹⁴C) and concentrations of dissolved CH₄in surface waters from the Coal Oil Point seep field to test the hypothesis that geological sources can dominate the regional background signal of CH₄. We find that surface waters with elevated CH₄concentration were populated with seep‐CH₄and that lower concentrations of CH₄were well explained by mixing with the regional background of nongeological CH₄. Substantial differences in concentration and¹⁴C‐CH₄were observed over distances <5 km, demonstrating that surface currents mix background‐CH₄into the seep field. These results indicate that even a prolific seep region like the Santa Barbara Basin exerts limited influence on the regional background of CH₄in the surface layer but is a significant driver of patchiness in oceanic CH₄biogeochemistry. 

Abstract. In the current era of rapid climate change, accuratecharacterization of climate-relevant gas dynamics – namely production,consumption, and net emissions – is required for all biomes, especially thoseecosystems most susceptible to the impact of change. Marine environmentsinclude regions that act as net sources or sinks for numerous climate-activetrace gases including methane (CH4) and nitrous oxide (N2O). Thetemporal and spatial distributions of CH4 and N2O are controlledby the interaction of complex biogeochemical and physical processes. Toevaluate and quantify how these mechanisms affect marine CH4 andN2O cycling requires a combination of traditional scientificdisciplines including oceanography, microbiology, and numerical modeling.Fundamental to these efforts is ensuring that the datasets produced byindependent scientists are comparable and interoperable. Equally critical istransparent communication within the research community about the technicalimprovements required to increase our collective understanding of marineCH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB)was organized to enhance dialogue and collaborations pertaining tomarine CH4 and N2O. Here, we summarize the outcomes from theworkshop to describe the challenges and opportunities for near-futureCH4 and N2O research in the marine environment.