Biogeochemical tools for characterizing organic carbon in inland aquatic ecosystems

Abstract

Integration of inland waters into regional and global carbon (C) budgets requires a comprehensive understanding of factors regulating organic carbon (OC) delivery and in situ processing. This study reviews advances in optical, molecular, and isotopic approaches to resolve the sources, ages, and transformations of OC in aquatic systems. OC characterization using excitation emission matrix spectra, Fourier transform ion cyclotron mass spectrometry, and nuclear magnetic resonance provides detailed molecular level insight. Radiocarbon isotopic approaches and compound‐specific techniques resolve the input, metabolic fate, and turnover time of OC in ecosystems ranging in size from streams to the open ocean. Accumulating evidence suggests that aquatic OC is composed of diverse biogeochemical components. We conclude with enduring and emerging questions that underscore the role of inland systems in the global C cycle and propose unique combinations of approaches to better discern their role in the delivery and transformation of OC from soils to seas.

Representing Organic Matter Thermodynamics in Biogeochemical Reactions via Substrate-Explicit Modeling

“…In the present study using OM profiles from FTICR-MS, lack of quantitative information (i.e., concentrations) on individual OM molecules is an intrinsic limitation. Consequently, we focused on evaluating carbon quality based on the normalized distribution of OM, but this gap can be filled for improving predictions, e.g., through the integration with other complementary metabolomics approaches that can provide quantitative data (Hertkorn et al, 2013;McCallister et al, 2018).…”

Representing Organic Matter Thermodynamics in Biogeochemical Reactions via Substrate-Explicit Modeling

“…Lack of quantitative information (i.e., concentrations) on individual OM molecules is an intrinsic limitation in analyzing OM profiles from FTICR-MS. Consequently, we focused on evaluating carbon quality based on the normalized distribution of OM, but this gap can be be filled for improving predictions, e.g., through the integration with other complementary metabolomics approaches that can provide quantitative data (Hertkorn et al, 2013;McCallister et al, 2018).…”

Mathematical chromatography deciphers the molecular fingerprints of dissolved organic matter

“…4,5 Among the array of analytical techniques used to fingerprint DOM, high-resolution mass spectrometry (HRMS) is generally considered to be the most advanced with regard to specificity and molecular insight. 6,7 In direct infusion mode, hundreds of mass spectral transients are collected and averaged, routinely generating more than 10 6 data points consisting of 10 3 to 10 4 molecular formulas. Since each molecular formula represents an unknown number of structural isomers, the true complexity far exceeds the observed size of the dataset.…”