Inferring Ecosystem Function from Dissolved Organic Matter Optical Properties: A Critical Review

Abstract

Over the last 30 years, the optical property community has shifted from conducting dissolved organic matter (DOM) measurements on new complex mixtures in natural and engineered systems to furthering ecosystem understanding in the context of past, present, and future carbon (C) cycling regimes. However, the appropriate use of optical properties to understand DOM behavior in complex biogeochemical systems is of recent debate. This critical review provides an extensive survey of DOM optical property literature across atmospheric, marine, and terrestrial biospheres using a categorical approach that probes each biosphere and its subdivisions. Using this approach, a rubric of ecosystem variables, such as productive nature, C cycling rate, C inputs, and water quality, sets the foundation for interpreting commonly used optical property DOM metrics such as fluorescence index (FI), humification index (HIX), and specific ultraviolet absorbance at 254 nm (SUVA 254 ). Case studies and a meta-analysis of each biosphere and subdivision found substantial overlap and characteristic distributions corresponding to ecosystem context for FI, HIX, and SUVA 254 , signifying chromophores and fluorophores from different ecosystems may be more similar than originally thought. This review challenges researchers to consider ecosystem connectivity when applying optical property results rather than making traditional “if this, then that” results-style conclusions.

Identification of next-generation International Humic Substances Society reference materials for advancing the understanding of the role of natural organic matter in the Anthropocene

“…This is apparent from simple spectroscopy measurements (Fig. 1) (D'Andrilli et al 2022) but is also evident from the suite of new analytical techniques such as high-resolution mass spectrometry, electrochemical redox characterizations, and improved functional group analysis (McAdams et al 2018;McKnight et al 2001;D'Andrilli et al 2013D'Andrilli et al , 2022Cawley et al 2013). A dendritic representation of NOM is more appropriate Fig.…”

Sources, spectral characteristics, and fluxes of dissolved organic matter in coastal groundwater and river water in western Guangdong, China

“…Previous studies showed that the optical parameters could provide valuable information on the source and composition of DOM in aquatic environments (Baker, 2001;Chen et al, 2010;Derrien et al, 2017;Li and Hur, 2017;D'Andrilli et al, 2022). The relatively high contribution of humic-like components to total FDOM fluorescence was found in both the groundwater (77 ± 18%) and river water samples (88 ± 7%), suggesting that the highly reworked humic-like molecules dominate the riverine and groundwater DOM pool (Figure 5A).…”

Unified Modeling Approach for Quantifying the Proton and Metal Binding Ability of Soil Dissolved Organic Matter

“…As shown in Figure b, n A values had a good linear correlation with SUVA 254 values, suggesting that other parameters may be also used for the modeling purpose to group DOM molecules. It is desired to elucidate the origins of these molecular groups and quantify them in a simple and direct way with mechanistic insights, for example, approaches combined with optical properties of DOM or with advanced computation methods (e.g., machine learning method). , Since both climate and soil properties significantly affect the compositions and properties of soil DOM, , we hope our results will help to predict the chemodiversity and reactivity of DOM in the soil environment by incorporating both the (bio)­geochemical processes and molecular-level insight into soil DOM models.…”