Persistence of dissolved organic matter explained by molecular changes during its passage through soil

Roth, Vanessa-Nina; Lange, Markus; Simon, Carsten; Hertkorn, Norbert; Bucher, Sebastian; Goodall, Tim; Griffiths, Robert I.; Mellado-Vázquez, Perla Griselle; Mommer, Liesje; Oram, Natalie J.; Weigelt, Alexandra; Dittmar, Thorsten; Gleixner, Gerd

doi:10.1038/s41561-019-0417-4

Cited by 307 publications

(271 citation statements)

References 73 publications

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“…This trend of continuous recycling and microbial transformation of DOM in contrast to the accumulation of recalcitrant molecules (that are chemically resistant to degradation), has been the topic of extensive discussion in the soil community (Marschner et al, 2008;Kaiser and Kalbitz, 2012;Lehmann and Kleber, 2015). Recently, Roth et al (2019) indicated that during the passage of DOM through soil, small plant-derived molecules were preferentially consumed and transformed into larger microorganism-derived molecules. Our results show that the transition from plant-derived to microorganism-derived DOM is reflected in groundwater as well.…”

Section: Relationship Of Dom Composition and Agementioning

confidence: 99%

Fueling Diversity in the Subsurface: Composition and Age of Dissolved Organic Matter in the Critical Zone

et al. 2019

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Surface ecosystems are rapidly changing on a global scale and it is important to understand how this influences aquifers in the subsurface, as groundwater quality is a major concern for future generations. Dissolved organic matter (DOM) contains molecular and isotopic signals from surface-derived inputs as well as from the biotic and abiotic subsurface environment and is therefore ideal to study the connectivity between both environments. We evaluated a 3-year time series of DOM composition using ultrahigh resolution mass spectrometry and age using 14 C accelerator mass spectrometry along a hillslope well transect in the fractured bedrock of the Hainich Critical Zone Exploratory, Germany. We found a wide range of DOM 14 C depletion, from 14 C = −47.9 to 14 C = −782.4, within different zones of the shallow groundwater. The 14 C content of DOM mirrored the connectivity of the aquifers to the surface. The composition of DOM was highly interrelated with its 14 C age. The proportions of surface-derived DOM components decreased with DOM age, whereas microorganismderived DOM components increased. The intensity of surface-sourced DOM signals differed between the wells and likely reflected the hydrological complexity of fracturedrock environments. During recharge, DOM was more enriched in 14 C, contained more surface-derived molecular components and was more diverse. As a potential response to the varying DOM substrate, bacterial 16S rRNA gene analysis revealed community evolution and increased bacterial diversity during recharge. The influx of diverse, surface-derived DOM potentially fueled evolution within the autochthonous bacterial communities, as in contrast to DOM, the bacterial community did not retreat to the initial diversity and community composition during the recession period. Our results demonstrate on the one hand that combined analyses of the composition and age of groundwater DOM strongly contribute to the understanding of interconnections, community evolution and the functioning of subsurface ecosystems and on the other hand that changes in surface ecosystems have an imprint on subsurface ecosystems.

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Section: Relationship Of Dom Composition and Agementioning

confidence: 99%

Fueling Diversity in the Subsurface: Composition and Age of Dissolved Organic Matter in the Critical Zone

et al. 2019

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“…Soil properties vary widely and influence the availability of numerous chemicals including nutrients, metals, and pollutants (8,9), making it likely that soil physicochemical characteristics play a key role in influencing the bioavailability of flavonoid molecules. Organic carbon (OC) is one abiotic soil property that is particularly important to study (10), because OC levels in soil are influenced by the rate of plant growth and of delivery of plant litter into an ecosystem. Furthermore, soil management strategies, including the addition of plant litter or organic amendments (e.g., wood, compost, and pyrolyzed OC), can greatly influence soil OC content (11).…”

Section: Introductionmentioning

confidence: 99%

Soil organic matter attenuates the efficacy of flavonoid-based plant-microbe communication

et al. 2020

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Plant-microbe interactions are mediated by signaling compounds that control vital plant functions, such as nodulation, defense, and allelopathy. While interruption of signaling is typically attributed to biological processes, potential abiotic controls remain less studied. Here, we show that higher organic carbon (OC) contents in soils repress flavonoid signals by up to 70%. Furthermore, the magnitude of repression is differentially dependent on the chemical structure of the signaling molecule, the availability of metal ions, and the source of the plant-derived OC. Up to 63% of the signaling repression occurs between dissolved OC and flavonoids rather than through flavonoid sorption to particulate OC. In plant experiments, OC interrupts the signaling between a legume and a nitrogen-fixing microbial symbiont, resulting in a 75% decrease in nodule formation. Our results suggest that soil OC decreases the lifetime of flavonoids underlying plant-microbe interactions.

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“…The sorbent and structural roles of Fe may increase soil C stocks by decreasing the availability of OM to extracellular enzymes and heterotrophic microbes 5,7 . A commonly accepted mechanism for MAOM formation is for dissolved organic matter (DOM) of plant or microbial origin 16 to sorb or co-precipitate with existing and de novo minerals 5,[17][18][19] . One particularly important route of MAOM formation involves the oxidation of Fe II to Fe III at redox interfaces and its rapid hydrolysis to SRO Fe III (oxyhydr)oxides, which coprecipitate with DOM 20 .…”

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Iron-mediated organic matter decomposition in humid soils can counteract protection

et al. 2020

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Soil organic matter (SOM) is correlated with reactive iron (Fe) in humid soils, but Fe also promotes SOM decomposition when oxygen (O 2) becomes limited. Here we quantify Femediated OM protection vs. decomposition by adding 13 C dissolved organic matter (DOM) and 57 Fe II to soil slurries incubated under static or fluctuating O 2. We find Fe uniformly protects OM only under static oxic conditions, and only when Fe and DOM are added together: de novo reactive Fe III phases suppress DOM and SOM mineralization by 35 and 47%, respectively. Conversely, adding 57 Fe II alone increases SOM mineralization by 8% following oxidation to 57 Fe III. Under O 2 limitation, de novo reactive 57 Fe III phases are preferentially reduced, increasing anaerobic mineralization of DOM and SOM by 74% and 32-41%, respectively. Periodic O 2 limitation is common in humid soils, so Fe does not intrinsically protect OM; rather reactive Fe phases require their own physiochemical protection to contribute to OM persistence.

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Persistence of dissolved organic matter explained by molecular changes during its passage through soil

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Cited by 307 publications

References 73 publications

Fueling Diversity in the Subsurface: Composition and Age of Dissolved Organic Matter in the Critical Zone

Fueling Diversity in the Subsurface: Composition and Age of Dissolved Organic Matter in the Critical Zone

Soil organic matter attenuates the efficacy of flavonoid-based plant-microbe communication

Iron-mediated organic matter decomposition in humid soils can counteract protection

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