Phosphorus Enhances Uptake of Dissolved Organic Matter in Boreal Streams

Mutschlecner, Audrey E.; Guerard, Jennifer J.; Jones, Jeremy B.; Harms, Tamara K.

doi:10.1007/s10021-017-0177-1

Cited by 15 publications

(18 citation statements)

References 89 publications

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“…Leaf litter is a likely contributor to DOM flushed during snowmelt (Spencer et al ), as evidenced in the present study by a high relative contribution of EEMs Component 5 during May of both years of the study (Fig. ), which was prevalent in leachates from boreal plant species (mean fluorescence loading = 41%; Mutschlecner et al ).…”

Section: Discussionsupporting

confidence: 66%

“…Parallel factor analysis (PARAFAC) was applied to resolve fluorescing components using the DOMFluor toolbox (version 1–7, Stedmon and Bro ) in MATLAB (version R2015b, MathWorks). The PARAFAC model was based on the 52 samples presented here, as well as additional samples to increase the power of the model, including a set of 45 samples of leachates derived from plant species common to the boreal region included in this study (Mutschlecner et al ), and 132 stream water samples that had been incubated and/or acidified, for a total of n = 229 samples supporting the model. A model including five components was best supported by the data as determined by inspection of residuals for random variation and model validation (Supporting Information Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, concentration of DON was determined as: DON 5 TDN 2 [NO 2 3 -N 1 NH 1 4 -N]. A proxy for groundwater inputs (GW) was calculated as the molar sum of Na 1 , Mg 21 , Cl 2 , and SO 22 4 , all of which are present in high concentration in local groundwater and behave conservatively in this region (O'Donnell et al 2010;Toohey et al 2016). When measured values were below the LOQ, the average of the LOQ and zero was used in data analysis.…”

Section: Chemical Analysismentioning

confidence: 99%

“…High-latitude catchments exhibit strong seasonality in the hydrologic regime, including variation in discharge and depth of groundwater flow, which influences the quantity and composition of DOM reaching rivers (Finlay et al 2006;O'Donnell et al 2010O'Donnell et al , 2012Mann et al 2012;Wickland et al 2012). Limited observations suggest that DOM exported from large Arctic rivers is labile during spring freshet (Holmes et al 2008;Wickland et al 2012) when runoff flows through organic-rich, upper soil layers, and yields terrestrially derived, aromatic DOM (Striegl et al 2007;Spencer et al 2008;Mann et al 2012).…”

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confidence: 99%

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Regional and intra‐annual stability of dissolved organic matter composition and biolability in high‐latitude Alaskan rivers

Mutschlecner

Guerard

Jones

et al. 2018

Limnology & Oceanography

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Nutrient availability and molecular composition of dissolved organic matter (DOM) determine whether the carbon (C) associated with DOM is respired during decomposition or exported from stream networks. High‐latitude ecosystems are changing rapidly due to permafrost thaw, shifts in vegetation, and increasing runoff, which alter sources of DOM and nutrients to rivers. To address how changes in the composition of riverine DOM and nutrients may influence C cycling, we quantified biolability of DOM across a latitudinal gradient in Alaska and assessed temporal patterns associated with intra‐annual variation in hydrology. We measured biolability under ambient and fertilized conditions and characterized optical and chemical properties of DOM to determine the relative influence of nutrients and molecular composition of DOM on its fate in rivers. Biolability was low, comprising 4% of the DOM pool on average and 0–42% across all sites and seasons. Optical indicators of the molecular composition of the DOM pool were more constant in space and time than bulk concentrations of dissolved C and nutrients, and described a DOM pool dominated by humic‐like functional groups. Phosphorus limited biolability at freshet, but biolability was not linked to DOM composition. Strong hydrologic connection of high‐latitude rivers to a large pool of soil organic matter likely results in export of recalcitrant DOM to receiving rivers and coasts in this region, contributing to stability of the high‐latitude C cycle. However, increased inputs of phosphorus or DOM of greater biolability will likely cause increased respiration of riverine DOM and flux of CO2 to the atmosphere.

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Section: Discussionsupporting

confidence: 66%

Section: Methodsmentioning

confidence: 99%

Section: Chemical Analysismentioning

confidence: 99%

mentioning

confidence: 99%

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Regional and intra‐annual stability of dissolved organic matter composition and biolability in high‐latitude Alaskan rivers

Mutschlecner

Guerard

Jones

et al. 2018

Limnology & Oceanography

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“…Local environmental conditions, such as nutrient availability or DOM composition, are also likely to influence DOC processing. The few studies examining the influence of nitrogen availability on DOC uptake metrics have reached contrasting results (Bechtold et al, ; Johnson et al, ; Martí & Sabater, ; Mutschlecner et al, ). Furthermore, research assessing the effects of ambient DOM composition on DOC uptake is even scarcer (Mineau et al, ; but see Lutz et al, ).…”

Section: Introductionmentioning

confidence: 99%

Behind the Scenes: Mechanisms Regulating Climatic Patterns of Dissolved Organic Carbon Uptake in Headwater Streams

Catalán

Casas-Ruiz

Arce

et al. 2018

Global Biogeochemical Cycles

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Large variability in dissolved organic carbon (DOC) uptake rates has been reported for headwater streams, but the causes of this variability are still not well understood. Here we assessed acetate uptake rates across 11 European streams comprising different ecoregions by using whole‐reach pulse acetate additions. We evaluated the main climatic and biogeochemical drivers of acetate uptake during two seasonal periods. Our results show a minor influence of sampling periods but a strong effect of climate and dissolved organic matter (DOM) composition on acetate uptake. In particular, mean annual precipitation explained half of the variability of the acetate uptake velocities (VfAcetate) across streams. Temperate streams presented the lowest VfAcetate, together with humic‐like DOM and the highest stream respiration rates. In contrast, higher VfAcetate were found in semiarid streams, with protein‐like DOM, indicating a dominance of reactive, labile compounds. This, together with lower stream respiration rates and molar ratios of DOC to nitrate, suggests a strong C limitation in semiarid streams, likely due to reduced inputs from the catchment. Overall, this study highlights the interplay of climate and DOM composition and its relevance to understand the biogeochemical mechanisms controlling DOC uptake in streams.

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