Molecular composition and bioavailability of dissolved organic nitrogen in a lake flow-influenced river in south Florida, USA

Pisani, Oliva; Boyer, Joseph N.; Podgorski, David C.; Thomas, Cassondra R.; Coley, Teresa L.; Jaffé, Rudolf

doi:10.1007/s00027-017-0540-5

Cited by 23 publications

(21 citation statements)

References 78 publications

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“…Although the T280 peak has previously been associated with amino‐acid like fluorescence, and in particular the amino acids tryptophan and tyrosine (Fellman et al, ), our data from streams across New Hampshire, show that T280 is a poor predictor of ambient DON concentrations. This suggests that the fraction of amino N in ambient stream water DON is low (Lusk & Toor, , Pisani et al, ), and that the effectiveness of existing fDOM sensors to provide information on DON concentrations will not be improved by sensors that employ a new excitation‐emission pair that differs from the one that we have used. Although the T280 peak has been used widely to assess amino acids‐like fluorescence and biological activity (e.g., Coble et al, ; Cory et al, ; Fellman et al, ; Hudson et al, ) in a range of sites including those receiving urban runoff and treated wastewater (Ahmad & Reynolds, ; Baker & Spencer, ; Hudson et al, ; Reynolds & Ahmad, ; Reynolds, ), ambient DON is considerably more diverse than the amino N component.…”

Section: Discussionmentioning

confidence: 90%

“…Although the T280 peak has previously been associated with aminoacid like fluorescence, and in particular the amino acids tryptophan and tyrosine (Fellman et al, 2010), our data from streams across New Hampshire, show that T280 is a poor predictor of ambient DON concentrations. This suggests that the fraction of amino N in ambient stream water DON is low (Lusk & Toor, 2016, Pisani et al, 2017, and that the effectiveness of existing fDOM sensors to provide information on DON concentrations will not be improved by sensors that employ a new excitation-emission pair that differs from the one that we have used. Although the T280 peak has been used widely to assess amino…”

Section: Effectiveness Of Various Optical Approaches To Measure Streamentioning

confidence: 97%

“…acids-like fluorescence and biological activity (e.g., Coble et al, 1990;Cory et al, 2011;Fellman et al, 2009Fellman et al, , 2010Hudson et al, 2008) in a range of sites including those receiving urban runoff and treated wastewater (Ahmad & Reynolds, 1999;Baker & Spencer, 2004;Hudson et al, 2008;Reynolds & Ahmad, 1997;Reynolds, 2002), ambient DON is considerably more diverse than the amino N component. Dissolved organic N in surface waters includes, for example, amino sugars (Gremm & Kaplan, 1997), N-containing organic acids (Hood et al, 2005), and larger lignin-like biopolymers (Lusk & Toor, 2016) with high-resolution mass spectroscopy identifying thousands of individual DON compounds (Lusk & Toor, 2016;Pisani et al, 2017). The utility of the T280 peak as a proxy for ambient DON is further limited because it is known to be responsive to other dissolved organic compounds such as gallic acid and tannin which fluoresce in a similar region but lack amino groups (Aiken, 2014;Maie et al, 2007).…”

Section: 1002/2017wr022168mentioning

confidence: 99%

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Using In‐Situ Optical Sensors to Understand the Biogeochemistry of Dissolved Organic Matter Across a Stream Network

Wymore

Potter

Rodriguez-Cardona

et al. 2018

Water Resources Research

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The advent of high‐frequency in situ optical sensors provides new opportunities to study the biogeochemistry of dissolved organic matter (DOM) in aquatic ecosystems. We used fDOM (fluorescent dissolved organic matter) to examine the spatial and temporal variability in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) across a heterogeneous stream network that varies in NO3− concentration. Across the ten study streams fDOM explained twice the variability in the concentration of DOC (r2 = 0.82) compared to DON (r2 = 0.39), which suggests that the N‐rich fraction of DOM is either more variable in its sources or more bioreactive than the more stable C‐rich fraction. Among sites, DON molar fluorescence was approximately 3x more variable than DOC molar fluorescence and was correlated with changes in inorganic N, indicating that DON is both more variable in composition as well as highly responsive to changes in inorganic N. Laboratory results also indicate that the fDOM sensors we used perform as well as the excitation‐emission wavelength pair generally referred to as the “tryptophan‐like” peak when measured under laboratory conditions. However, since neither the field sensor not the laboratory measurements explained a large percentage of variation in DON concentrations, challenges still remain for monitoring the ambient pool of dissolved organic nitrogen. Sensor networks provide new insights into the potential reactivity of DOM and the variability in DOC and DON biogeochemistry across sites. These insights are needed to build spatially explicit models describing organic matter dynamics and water quality.

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Section: Discussionmentioning

confidence: 90%

Section: Effectiveness Of Various Optical Approaches To Measure Streamentioning

confidence: 97%

Section: 1002/2017wr022168mentioning

confidence: 99%

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Using In‐Situ Optical Sensors to Understand the Biogeochemistry of Dissolved Organic Matter Across a Stream Network

Wymore

Potter

Rodriguez-Cardona

et al. 2018

Water Resources Research

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“…The stoichiometry of DOM to nutrients plays a crucial role in regulating nutrient cycling (Berggren et al 2015;Stutter et al 2018;Yates et al 2019). The DON and DOP contributions to the DOM pool are dependent on its source and composition (Pisani et al 2020;Yates et al 2019) and have been shown to be positively correlated to DOM bioavailability (Jansson et al 2012;Pisani et al 2017;Thompson and Cotner 2018). The amount of bioavailable material can range from 10 to 70% of riverine DON (Pisani et al 2017) and 0 to 90% of DOP (Li and Brett 2013) with quantities dependant on inputs and sources of terrestrial runoff and photodegradation processes (Moran and Zepp 1997).…”

Section: The Chemical Composition Of the Dom Pool Can Modify Nutrient Cyclesmentioning

confidence: 99%

How humans alter dissolved organic matter composition in freshwater: relevance for the Earth’s biogeochemistry

et al. 2021

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Dissolved organic matter (DOM) is recognized for its importance in freshwater ecosystems, but historical reliance on DOM quantity rather than indicators of DOM composition has led to an incomplete understanding of DOM and an underestimation of its role and importance in biogeochemical processes. A single sample of DOM can be composed of tens of thousands of distinct molecules. Each of these unique DOM molecules has their own chemical properties and reactivity or role in the environment. Human activities can modify DOM composition and recent research has uncovered distinct DOM pools laced with human markers and footprints. Here we review how land use change, climate change, nutrient pollution, browning, wildfires, and dams can change DOM composition which in turn will affect internal processing of freshwater DOM. We then describe how human-modified DOM can affect biogeochemical processes. Drought, wildfires, cultivated land use, eutrophication, climate change driven permafrost thaw, and other human stressors can shift the composition of DOM in freshwater ecosystems increasing the relative contribution of microbial-like and aliphatic components. In contrast, increases in precipitation may shift DOM towards more relatively humic-rich, allochthonous forms of DOM. These shifts in DOM pools will likely have highly contrasting effects on carbon outgassing and burial, nutrient cycles, ecosystem metabolism, metal toxicity, and the treatments needed to produce clean drinking water. A deeper understanding of the links between the chemical properties of DOM and biogeochemical dynamics can help to address important future environmental issues, such as the transfer of organic contaminants through food webs, alterations to nitrogen cycling, impacts on drinking water quality, and biogeochemical effects of global climate change.

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“…Recent advances in high-resolution analytical chemistry techniques (e.g., pyrolysis GC/MS, Fourier Transformation Ion Cyclotron Resonance MS) provide powerful insights into how the chemistry and molecular structure of DOM vary over space and time and can provide insight into how variability in DOM composition relates to the cycling of inorganic N. Relevant DOM variability can be described at relatively coarse levels of resolution such as the relative abundance of Ncontaining compounds (e.g., Lusk and Toor, 2016;Pisani et al, 2017) or how the 3-D molecular structure determines the availability of N and the energy expenditure required for acquiring nutrients from the ambient pool of DOM. For example, some sources of N can be more easily accessed such as terminal amine groups, while others may exist in more protected and unavailable forms such as heterocyclic organic molecules that stabilize the N through multiple covalent bonds.…”

Section: Eq 1: How Does Variability In Dom Composition Influence N Prmentioning

confidence: 99%

LINX I and II: Lessons Learned and Emerging Questions

Wymore

Rodriguez-Cardona

Herreid

et al. 2019

Front. Environ. Sci.

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The Lotic Intersite Nitrogen eXperiments (LINX I and II) were a series of replicated in situ manipulations of 15 N across biomes and land-uses designed to assess the factors that control the removal, retention, and ultimate fate of inorganic nitrogen in stream ecosystems. By studying streams at the continental scale, the lessons learned provide some of the best data available to understand the functional role of streams across the landscape, the management implications of nitrogen uptake in streams and rivers, and the value of small streams in elucidating fundamental principles of ecosystem science. Because small streams are characterized by high throughput and low standing stocks of primary producers and stored carbon and nutrients, they provide unique opportunities to assess the fundamental drivers of nitrogen cycling that would be difficult to conduct in other ecosystems. In addition to the water quality implications of understanding controls on nitrogen delivery to downstream systems, LINX I and II also provide unique insights for ecosystem science and stream ecology more broadly. Here we review a series of ecosystem and network-scale lessons that can be inferred from LINX I and II. We then propose three emergent research questions motivated by the LINX projects which are amenable to future continental-scale work. LINX I and II also demonstrate the value of a highly collaborative, distributed approach to ecosystem science that requires each member of the team to conduct a standardized protocol while simultaneously encouraging team member to improve protocols and develop cross-site projects in his or her specific area of expertise.

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Molecular composition and bioavailability of dissolved organic nitrogen in a lake flow-influenced river in south Florida, USA

Cited by 23 publications

References 78 publications

Using In‐Situ Optical Sensors to Understand the Biogeochemistry of Dissolved Organic Matter Across a Stream Network

Using In‐Situ Optical Sensors to Understand the Biogeochemistry of Dissolved Organic Matter Across a Stream Network

How humans alter dissolved organic matter composition in freshwater: relevance for the Earth’s biogeochemistry

LINX I and II: Lessons Learned and Emerging Questions

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