Export of photolabile and photoprimable dissolved organic carbon from the Connecticut River

Yoon, Byunghoon; Hosen, Jacob D.; Kyzivat, E. D.; Fair, Jennifer H.; Weber, L.; Aho, Kelly S.; Lowenthal, R. S.; Matt, Serena; Sobczak, William V.; Shanley, J. B.; Morrison, J Rodolfo; Saiers, James E.; Stubbins, Aron; Raymond, Peter A.

doi:10.1007/s00027-021-00778-8

Cited by 6 publications

(6 citation statements)

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“…Given that the existing work has shown a single lake can eliminate more than 10% of the DOC (i.e., R r > 0.10), and that approximately one quarter of the reaches in the CRW are classified as lentic, it is probable that the cumulative watershed elimination could be important when lentic systems are included. Previous studies have additionally shown for both rivers and estuaries that photobleaching or photo‐bleachable DOC represents a major portion (>50%) of the DOC pool, despite possibly minor DOC photomineralization (Clark et al, 2020; Fichot & Benner, 2014; Yoon et al., 2021). We further note that our study does not directly compare photomineralization rates with bio‐mineralization (respiration) rates, which has been a metric used in past studies to identify photo‐alteration as an important (Cory et al., 2014) or unimportant process (Rocher‐Ros et al, 2021).…”

Section: Resultsmentioning

confidence: 99%

“…In this study, we develop a spatially explicit model of complete DOC photooxidation to DIC, that is, photomineralization, for the riverine reaches of the Connecticut River Watershed (CRW), a temperate river basin in the northeastern United States and southern Canada. Yoon et al (2021) suggested there is potential for a large flux of photolabile DOC to escape the CRW annually, suggesting low photomineralization, but it remains unclear how much is photomineralized within the watershed itself. These findings, combined with the observations in existing literature that photomineralization fluxes typically only exceed ∼10% of the total DOC consumption in systems with long water residence times like lakes and coastal plumes, or in regions with low canopy cover (e.g., Arctic environments), lead us to hypothesize that photomineralization is a minor process in temperate rivers where water residence times are low and canopy cover is high.…”

Section: Of 18mentioning

confidence: 99%

“…Although losses of photoreactive DOC within river systems have proved difficult to assess, there is a wealth of evidence that photoreactive DOC escapes rivers to the oceans. For instance, many studies report high export of CDOM and photolabile DOC to the oceans, suggesting that rivers in general are poor photoreactors of DOC (Spencer et al., 2013; Vodacek et al., 1997; Yoon et al., 2021). Our ability to quantify the relative importance of photomineralization as a DOC sink remains limited if it is not calculated in the context of the flux or concentration of DOC through a river reach over timescales of interest (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

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Does Photomineralization of Dissolved Organics Matter in Temperate Rivers?

et al. 2021

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Dissolved organic matter (DOM) is one of the largest fluxes of carbon in inland water ecosystems and a central component of riverine metabolism. DOM, which is approximately 50% dissolved organic carbon (DOC) by mass (Dittmar & Stubbins, 2014;Krogh, 1934), is a nutrient and energy source, capable of transporting metals and pollutants, and a driver of light availability in water bodies (Kaplan & Cory, 2016;Schlesinger & Melack, 1981). Large amounts of riverine DOC enter the ocean annually, where it is an important source of reduced carbon (Raymond & Spencer, 2015). Although the amount of DOC entering the ocean is relatively well known, its representative chemical composition, reactivity, and the seasonality of its input are not as

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Section: Resultsmentioning

confidence: 99%

Section: Of 18mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Does Photomineralization of Dissolved Organics Matter in Temperate Rivers?

et al. 2021

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“…High rates of autochthonous primary production and photodegradation of aromatic DOM results in delivery of autochthonous, photodegraded DOM from lakes to streams and rivers downstream (Larson et al, 2007) due to an enhanced light field (Julian et al, 2013). This lacustrine DOM is thus highly labile and can be quickly taken up by microbial communities (Chróst et al, 1989; Mostovaya et al, 2016; Yoon et al, 2021) and the influence of lakes and reservoirs on DOM composition may disappear quickly as water moves downstream. Thus, the signal of lake processes on DOM composition may be lost downstream if all the lake‐associated DOM is converted to biomass, mineralized, or transformed into dissolved compounds that resemble riverine DOM.…”

Section: Discussionmentioning

confidence: 99%

River network travel time is correlated with dissolved organic matter composition in rivers of the contiguous United States

Hosen

Allen

Amatuli

et al. 2021

Hydrological Processes

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Most terrestrial allochthonous organic matter enters river networks through headwater streams during high flow events. In headwaters, allochthonous inputs are substantial and variable, but become less important in streams and rivers with larger watersheds. As allochthonous dissolved organic matter (DOM) moves downstream, the proportion of less aromatic organic matter with autochthonous characteristics increases. How environmental factors converge to control this transformation of DOM at a continental scale is less certain. We hypothesized that the amount of time water has spent travelling through surface waters of inland systems (streams, rivers, lakes, and reservoirs) is correlated to DOM composition. To test this hypothesis, we used established river network scaling relationships to predict relative river network flow-weighted travel time (FWTT) of water for 60 stream and river sites across the contiguous United States (3090 discrete samples over 10 water years). We estimated lentic contribution to travel times with upstream in-network lake and reservoir volume. DOM composition was quantified using ultraviolet and visible absorption and fluorescence spectroscopy. A combination of FWTT and lake and reservoir volume was the best overall predictor of DOM composition among models that also incorporated discharge, specific discharge, watershed area, and upstream channel length. DOM spectral slope ratio (R 2 = 0.77) and Freshness Index (R 2 = 0.78) increased and specific ultraviolet absorbance at 254 nm (R 2 = 0.68) and Humification Index (R 2 = 0.44) decreased across sites as a function of FWTT and upstream lake volume. This indicates autochthonous-like DOM becomes continually more dominant in waters with greater FWTT. We assert that river FWTT can be used as a metric of the continuum of DOM composition from headwaters to rivers. The nature of the changes to DOM composition detected suggest this continuum is driven by a combination of photo-oxidation, biological processes, hydrologically varying terrestrial subsidies, and aged groundwater inputs.

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“…We develop a spatially explicit mass balance model of DOC sources, sinks, and transport through the Connecticut River watershed in the northeastern United States and southern Canada. An existing body of literature dedicated to quantifying Connecticut River watershed metabolism, carbon dynamics, and hydrology make the Connecticut an ideal watershed for such an exercise, as ample information is available to parameterize a model (Hosen et al 2019; Brinkerhoff et al 2021; Hosen et al 2021; Maavara et al 2021; Yoon et al 2021; Aho et al 2021 a , b ). We track terrestrial DOC loading, production via GPP, consumption by microbial uptake (biomineralization) and photomineralization and the cascading downstream transport through 98,254 stream reaches and lake segments at an average length resolution of 511 m, from first order through 8 th ‐order streams, rivers, ponds, lakes, and reservoirs.…”

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Watershed DOC uptake occurs mostly in lakes in the summer and in rivers in the winter

Maavara

Brinkerhoff

Hosen

et al. 2023

Limnology & Oceanography

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River networks transport dissolved organic carbon (DOC) from terrestrial uplands to the coastal ocean. The extent to which a reach or lake within a river network uptakes DOC depends on the stream order, the seasonal conditions, and the flow. At the watershed scale, it remains unclear whether DOC uptake is dominated by biological processes such as respiration, or abiotic processes like photomineralization. The partitioning of DOC uptake in lakes vs. rivers is also unclear. In this study, we present a new model that unifies year-round controls on DOC cycling for an entire river network, including river-lake connectivity, to elucidate the importance of biotic vs. abiotic controls on DOC uptake. We present the Catchment UPtake and Sinks by Season, Order, and Flow for DOC (CUPS-OF-DOC) model, which quantifies terrestrial DOC loading, gross primary productivity, and uptake via microbes and photomineralization. The model is applied to the Connecticut River Watershed, and accounts for cascading reach-and lake-scale DOC cycling across 98 scenarios spanning combinations of flows, seasons, and stream orders. We show that riverine DOC uptake is nearly constant with stream order, but the proportion of DOC uptake from photomineralization varies. Photomineralization dominates in rivers in most flow conditions and stream orders, especially in winter, accounting for at least half of whole-watershed DOC uptake in February across all flows. Whole-watershed summer DOC uptake occurs mostly via biomineralization in lakes, accounting for 80% of DOC uptake during the growing season, despite accounting for less than 6% of watershed open water surface area.

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Export of photolabile and photoprimable dissolved organic carbon from the Connecticut River

Cited by 6 publications

References 105 publications

Does Photomineralization of Dissolved Organics Matter in Temperate Rivers?

Does Photomineralization of Dissolved Organics Matter in Temperate Rivers?

River network travel time is correlated with dissolved organic matter composition in rivers of the contiguous United States

Watershed DOC uptake occurs mostly in lakes in the summer and in rivers in the winter

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