Description of Dissolved Organic Matter Transformational Networks at the Molecular Level

Abstract

Dissolved Organic Matter (DOM) is an important component of the global carbon cycle. Unscrambling the structural footprint of DOM is key to understand its biogeochemical transformations at the mechanistic level. Although numerous studies have improved our knowledge of DOM chemical makeup, its three-dimensional picture remains largely unrevealed. In this work, we compare four solid phase extracted (SPE) DOM samples from three different freshwater ecosystems using high resolution mobility and ultrahigh-resolution Fourier transform ion cyclotron resonance tandem mass spectrometry (FT-ICR MS/MS). Structural families were identified based on neutral losses at the level of nominal mass using continuous accumulation of selected ions-collision induced dissociation (CASI-CID)FT-ICR MS/MS. Comparison of the structural families indicated dissimilarities in the structural footprint of this sample set. The structural family representation using Cytoscape software revealed characteristic clustering patterns among the DOM samples, thus confirming clear differences at the structural level (Only 10% is common across the four samples.). The analysis at the level of neutral loss-based functionalities suggests that hydration and carboxylation are ubiquitous transformational processes across the three ecosystems. In contrast, transformation mechanisms involving methoxy moieties may be constrained in estuarine systems due to extensive upstream lignin biodegradation. The inclusion of the isomeric content (mobility measurements at the level of chemical formula) in the structural family description suggests that additional transformation pathways and/or source variations are possible and account for the dissimilarities observed. While the structural character of more and diverse types of DOM samples needs to be assessed and added to this database, the results presented here demonstrate that Graph-DOM is a powerful tool capable of providing novel information on the DOM chemical footprint, based on structural interconnections of precursor molecules generated by fragmentation pathways and collisional cross sections.

Temperature-Dependent Molecular Evolution of Biochar-Derived Dissolved Black Carbon and Its Interaction Mechanism with Polyvinyl Chloride Microplastics

“…For example, FT–ICR MS/MS allows for the isomeric separation and structural assignment of DBC components with reduced ambiguities . Based on the neutral loss patterns of nominal mass isolated precursors, using continuous accumulation of selected ions followed by collision-induced dissociation and FT–ICR MS detection can identify the DBC structural families related components from nominal masses . The structurally interconnected DBC families can be visualized by combining with a novel visualization approach based on a Cytoscape network, identifying the biogeochemical transformation processes of DBCs …”

“…78 The structurally interconnected DBC families can be visualized by combining with a novel visualization approach based on a Cytoscape network, identifying the biogeochemical transformation processes of DBCs. 78 ■ ASSOCIATED CONTENT * sı Supporting Information…”

Linking Redox Characteristics to Dissolved Organic Matter Derived from Different Biowaste Composts: A Theoretical Modeling Approach Based on FT–ICR MS Analysis

“…1,2 The properties of molecular structures of DOM in compost are crucial for understanding their role in the provision of soil ecosystem services and sustainable management, 3,4 based on the function of governing redox reactions, sorption, and complexation processes. 5,6 However, there has been limited research on the heterogeneous and diverse compositions of DOM that affect its functions at the molecular level in composting systems, making it challenging to account for the chemical complexity of DOM molecules in theoretical modeling.…”

“…This approach is particularly important given the strong advocacy for organic fertilizers over chemical ones. In the composting process, dissolved organic matter (DOM) provides essential energy and critical building blocks for the structure and function, as it consists of a complex and heterogeneous continuum of water-soluble organic molecules. , The properties of molecular structures of DOM in compost are crucial for understanding their role in the provision of soil ecosystem services and sustainable management, , based on the function of governing redox reactions, sorption, and complexation processes. , However, there has been limited research on the heterogeneous and diverse compositions of DOM that affect its functions at the molecular level in composting systems, making it challenging to account for the chemical complexity of DOM molecules in theoretical modeling.…”

Origin of Dissolved Organic Matter in Deep Groundwater of Marine Deposits and Its Implication for Metal Binding

“…DOM is not a molecular entity with a specific structure but a collection of organic molecules (OMs) with varying compositions, reflecting different sources of constituent OMs and geochemical processes that alter OMs. ,, The spatial variation of DOM compositions is important for its role in contaminant transport in nature. For deep groundwater, DOM can be derived from OMs from surface environments by infiltration of rainwater through soil, OMs dissolved from sedimentary rocks, or OMs resulting from local microbial activities. − The autochthonous OM inputs and in situ decomposition and production of OMs catalyzed by microbial activities and mineral surfaces are particularly important for deep groundwater with sedimentary rocks, which contain relatively large amounts of OMs.…”