Applying the core-satellite species concept: Characteristics of rare and common riverine dissolved organic matter

Abstract

IntroductionDissolved organic matter (DOM) composition varies over space and time, with a multitude of factors driving the presence or absence of each compound found in the complex DOM mixture. Compounds ubiquitously present across a wide range of river systems (hereafter termed core compounds) may differ in chemical composition and reactivity from compounds present in only a few settings (hereafter termed satellite compounds). Here, we investigated the spatial patterns in DOM molecular formulae presence (occupancy) in surface water and sediments across 97 river corridors at a continental scale using the “Worldwide Hydrobiogeochemical Observation Network for Dynamic River Systems—WHONDRS” research consortium.MethodsWe used a novel data-driven approach to identify core and satellite compounds and compared their molecular properties identified with Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS).ResultsWe found that core compounds clustered around intermediate hydrogen/carbon and oxygen/carbon ratios across both sediment and surface water samples, whereas the satellite compounds varied widely in their elemental composition. Within surface water samples, core compounds were dominated by lignin-like formulae, whereas protein-like formulae dominated the core pool in sediment samples. In contrast, satellite molecular formulae were more evenly distributed between compound classes in both sediment and water molecules. Core compounds found in both sediment and water exhibited lower molecular mass, lower oxidation state, and a higher degree of aromaticity, and were inferred to be more persistent than global satellite compounds. Higher putative biochemical transformations were found in core than satellite compounds, suggesting that the core pool was more processed.DiscussionThe observed differences in chemical properties of core and satellite compounds point to potential differences in their sources and contribution to DOM processing in river corridors. Overall, our work points to the potential of data-driven approaches separating rare and common compounds to reduce some of the complexity inherent in studying riverine DOM.

Spatially Intensive Patterns of Water Clarity in Reservoirs Determined Rapidly With Sensor‐Equipped Boats and Satellites

“…How much surface area or volume do observations over the deepest point represent? More spatial surveys across a wider range of systems and dates would be necessary to address these questions effectively, in part because photosynthetic pigments and the dissolved organic matter pool (Stadler et al, 2023) also influence satellite indices of optical water quality and relationships like the one shown Figure 4. Stated another way, environmental water is a complex mixture of particulate and dissolved substances that together affect surface reflectance, and more than one model may be useful or necessary to represent constituent gradients within different kinds of mixtures.…”

Opening Doors to Physical Sample Data Discovery, Integration, and Credit

“…Analysis and visualizations from the sample set were incorporated into formally published datasets for longterm preservation and documentation in the Environmental System Science Data Infrastructure for a Virtual Ecosystem (ESS-DIVE) data repository 55,56 . These datasets were then referenced in the final journal publications associated with the data [57][58][59][60] .…”

Universal microbial reworking of dissolved organic matter along environmental gradients

“…Compounds with structural features such as carboxylic-rich alicyclic moieties, material derived from linear terpenoids, and carotenoid degradation products dominate this increasingly homogeneous pool 11 . As these compounds occur everywhere, that is, in all samples, they are termed “universal” 12 or “core” 13 . The convergence towards a DOM pool dominated by universal compounds is known as a “degradation cascade”.…”