Biodegradability of dissolved organic carbon in the Yukon River and its tributaries: Seasonality and importance of inorganic nitrogen

Abstract. Numerous recent studies have indicated that dissolved organic carbon (DOC) and nitrogen (DON) play an important role in C and N cycling in natural ecosystems, and have shown that N deposition alters the concentrations and fluxes of dissolved organic substances and may increase leaching losses from forests. Our study was set up to accurately quantify concentrations and flux patterns of DOC, DON and dissolved inorganic nitrogen (DIN) in deciduous and coniferous forest in Flanders, Belgium, under historical high nitrogen deposition. We measured DOC, DON and DIN concentrations at two weekly intervals in a silver birch (SB) stand, a corsican pine (CP) stand and a pine stand with higher N deposition (CPN), and used the SWAP model (calibrated with PEST) for generating accurate water and matter fluxes. The input with precipitation was an important source of DON, but not for DOC. Release of DOC from the forest floor was minimally affected by forest type, but higher N deposition (CPN stand) caused an 82% increase of DOC release from the forest floor. Adsorption to mineral soil material rich in iron and/or aluminum oxyhydroxides was suggested to be the most important process removing DOC from the soil solution, responsible for substantial retention (67–84%) of DOC entering the mineral soil profile with forest floor leachate. Generally, DON was less reactive (i.e. less removal from the soil solution) than DOC, resulting in decreasing DOC/DON ratios with soil depth. We found increased DOC retention in the mineral soil as a result of higher N deposition (84 kg ha−1 yr−1 additional DOC retention in CPN compared to CP). Overall DON leaching losses were 2.2, 3.3 and 5.0 kg N yr−1 for SB, CP and CPN, respectively, contributing between 9–28% to total dissolved N (TDN) leaching. The relative contribution to TDN leaching from DON loss from SB and CP was mainly determined by (large) differences in DIN leaching. The large TDN leaching losses are alarming, especially in the CPN stand that was N saturated.

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Available Dissolved Organic Carbon Alters Uptake and Recycling of Phosphorus and Nitrogen from River Sediments

Water ◽

10.3390/w12123321 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3321

Author(s):

Marc Stutter ◽

Daniel Graeber ◽

Gabriele Weigelhofer

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Nutrient Uptake ◽

Inorganic Nitrogen ◽

River Sediments ◽

Carbon Sources ◽

P Uptake ◽

Stream Sediments ◽

Organic C ◽

Flow Through

Concurrent with nutrient pollution, agriculture has significantly impacted the quantity, composition, and bioavailability of catchment-derived dissolved organic carbon (DOC) in stream ecosystems. Based on the stoichiometric theory, we tested the hypothesis that bioavailable DOC will stimulate the heterotrophic uptake of soluble reactive P (SRP) and inorganic nitrogen in stream sediments. In a simplified laboratory column flow-through study, we exposed stream sediments to additions of glucose, nitrate, and phosphate alone and in combination (+C, +NP, +CNP), and calculated gross and net changes in DOC and nutrients via a mass balance approach. Our results show that glucose-C increased nutrient uptake, but also that NP additions resulted in the enhanced consumption of both native and added organic C. The effects of C addition were stronger on N than P uptake, presumably because labile C stimulated both assimilation and denitrification, while part of the P uptake was due to adsorption. Internal cycling affected net nutrient uptake due to losses of dissolved organically-complexed P and N (DOP and DON). Overall, our study shows that increases in the stoichiometric availability of organic carbon can stimulate N and P sequestration in nutrient-polluted stream sediments. Future studies are required to assess the effects of complex organic carbon sources on nutrient uptake in stream sediments under different environmental conditions, and whether these stoichiometric relations are relevant for ecosystem management.

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Importance of within-lake processes in affecting the dynamics of dissolved organic carbon and dissolved organic and inorganic nitrogen in an Adirondack forested lake/watershed

Biogeosciences ◽

10.5194/bg-13-2787-2016 ◽

2016 ◽

Vol 13 (9) ◽

pp. 2787-2801 ◽

Cited By ~ 7

Author(s):

Phil-Goo Kang ◽

Myron J. Mitchell ◽

Patrick J. McHale ◽

Charles T. Driscoll ◽

Shreeram Inamdar ◽

...

Keyword(s):

New York ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Inorganic Nitrogen ◽

Pearson Correlation ◽

Forested Watersheds ◽

Lake Outlet ◽

Dormant Season ◽

The Difference

Abstract. Lakes nested in forested watersheds play an important role in mediating the concentrations and fluxes of dissolved organic matter. We compared long-term patterns of concentrations and fluxes of dissolved organic carbon (DOC) and dissolved organic (DON) and inorganic nitrogen (DIN) in aquatic ecosystems of the Arbutus Lake watershed to evaluate how a lake nested in a forested watershed affects the sources (e.g., production) and sinks (e.g., retention) of DOC and DON in the Adirondack Mountains of New York, USA. We observed no significant long-term changes of DOC and DON in the lake outlet since 1983 and 1994, respectively. However, the temporal patterns of DOC and DON concentrations in the lake inlet showed significant seasonality such as increases during the vegetation-growing season along with notable decreases in the dormant season. A comparison of mass balances between inlet and outlet for the period from 2000 to 2009 suggested that the lake was a sink of DOC (mean of influx minus outflux: +1140 mol C ha−1 yr−1). In contrast, the difference of discharge-weighted DON concentrations (mean of inlet minus outlet: −1.0 µmol N L−1) between inlet and outlet was much smaller than the discharge-weighted DOC concentrations (average of inlet minus outlet: + 87 µmol C L−1). DON fluxes showed considerable variation among years (mean of influx minus outflux: +8 mol N ha−1 yr−1; range of differences: −15 to 27 mol N ha−1 yr−1). DON exhibited low percent retention ((influx-outflux)/influx) (mean: 6.9 %, range: −34.8 to +31.2) compared to DOC (mean: 30.1 %, range: +9.2 to +44.1). The resultant increase of DON within the lake was closely linked with a net decrease of DIN through monthly Pearson correlation analysis, suggesting the importance of biotic factors in mediating lake DON dynamics. Our results show different relative retentions of DOC compared with DON, along with a larger retention of DIN than DON, suggesting that DOC and DON might display substantially different biogeochemical relationships in oligo-mesotrophic lakes nested forested watersheds and therefore different roles for a sink behavior for DOC compared to a producer of DON.

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Synergistic effects of dissolved organic carbon and inorganic nitrogen on methane uptake in forest soils without and with freezing treatment

Scientific Reports ◽

10.1038/srep32555 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 6

Author(s):

Haohao Wu ◽

Xingkai Xu ◽

Cuntao Duan ◽

Tuansheng Li ◽

Weiguo Cheng

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Forest Soils ◽

Synergistic Effects ◽

Inorganic Nitrogen ◽

Soil Core ◽

N Addition ◽

Forest Stands ◽

Inhibition Effect ◽

Freezing Treatment

Abstract There is limited knowledge about how the interaction of dissolved organic carbon (DOC) and inorganic nitrogen (N) released into the soil just after freezing can affect methane (CH4) uptake in forest soils. Here, we present how freezing treatment and glucose, as a DOC source, can affect the roles of NH4 +-N and NO3 −-N in inhibiting soil CH4 uptake, by using soil-core incubation experiments. A long-term freezing at low temperature reduced cumulative CH4 uptake in the soils sampled from two temperate forest stands without carbon (C) and N addition. The inhibition effects of N addition as NH4Cl and KNO3 on the soil CH4 uptake were much larger than C addition. Freezing treatment eliminated the inhibition effect of NH4Cl and KNO3 addition on CH4 uptake, and this response was affected by glucose addition and forest types. The addition of glucose eliminated the inhibition effect of NO3 −-N on CH4 uptake in the forest soils without and with freezing treatment, while the addition of NH4 +-N and glucose inhibited synergistically the soil CH4 uptake. The results highlight the importance of synergistic effects of DOC and N inputs on the soil CH4 uptake under forest stands during soil wetting and thawing periods.

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Importance of within-lake processes in affecting the dynamics of dissolved organic carbon and dissolved organic and inorganic nitrogen in an Adirondack forested lake/watershed

Biogeosciences Discussions ◽

10.5194/bgd-12-17285-2015 ◽

2015 ◽

Vol 12 (20) ◽

pp. 17285-17327

Author(s):

P.-G. Kang ◽

M. J. Mitchell ◽

P. J. McHale ◽

C. T. Driscoll ◽

M. R. McHale ◽

...

Keyword(s):

New York ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Inorganic Nitrogen ◽

Pearson Correlation ◽

New York State ◽

Forested Watersheds ◽

Lake Outlet ◽

The Difference

Abstract. Lakes nested in forested watersheds play important roles in mediating the concentrations and fluxes of dissolved organic matter. We compared long-term patterns of concentrations and fluxes of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved inorganic nitrogen (DIN) in the Arbutus Lake Watershed to evaluate how a lake nested in a forested watershed affects the dynamics of DOC and DON in the Adirondack Mountains of New York State, USA. We observed no significant long-term changes of concentrations and fluxes of DOC and DON in the Lake outlet since 1983 and 1994, respectively. However, the temporal patterns of DOC and DON concentrations in the Lake inlet showed significant seasonality such as increases during the vegetation-growing season along with notable decreases in the dormant season. A comparison of mass-balances between inlet and outlet for the period from 2000 to 2009 suggested that the Lake was a sink of DOC (mean of influx minus outflux: +1140 mol C ha−1 yr−1). In contrast, the difference of discharge-weighted DON concentrations (mean of inlet minus outlet: −1.0 μmol N L−1) between inlet and outlet was much smaller than the discharge-weighted DOC concentrations (average of inlet minus outlet: +87 μmol C L−1). DON fluxes showed considerable variation among years (mean of influx minus outflux: +8 mol N ha−1 yr−1; range of differences: −15 to 27 mol N ha−1 yr−1). DON exhibited low % retention ((influx − outflux) / influx) (mean: 6.9 %, range: −34.8 to +31.2) compared to DOC (mean: 30.1 %, range: +9.2 to +44.1). The resultant increase of DON within the lake was closely linked with a net decrease of DIN through monthly Pearson correlation analysis, suggesting the importance of biotic factors in mediating a lake DON dynamics. Our results show different relative retentions of DOC compared with DON, along with a larger retention of DIN than DON, suggesting that DOC and DON might display substantially different biogeochemical relationships in oligo-mesotrophic lakes nested forested watersheds and therefore different roles for a sink behavior for DOC compared to a producer of DON.

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Patterns of dissolved organic carbon (DOC) and nitrogen (DON) fluxes in deciduous and coniferous forests under historic high nitrogen deposition

Biogeosciences Discussions ◽

10.5194/bgd-6-7133-2009 ◽

2009 ◽

Vol 6 (4) ◽

pp. 7133-7173 ◽

Cited By ~ 3

Author(s):

S. Sleutel ◽

J. Vandenbruwane ◽

A. De Schrijver ◽

K. Wuyts ◽

B. Moeskops ◽

...

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Nitrogen Deposition ◽

Soil Solution ◽

Forest Floor ◽

Inorganic Nitrogen ◽

Mineral Soil ◽

N Deposition ◽

High Nitrogen ◽

Leaching Losses

Abstract. Numerous recent studies have indicated that dissolved organic carbon (DOC) and nitrogen (DON) play an important role in C and N cycling in natural ecosystems, and have shown that N deposition alters the concentrations and fluxes of dissolved organic substances and may increase leaching losses from forests. Our study was set up to accurately quantify concentrations and flux patterns of DOC, DON and dissolved inorganic nitrogen (DIN) in deciduous and coniferous forest in Flanders under historical high nitrogen deposition. We measured DOC, DON and DIN concentrations at two weekly intervals in a silver birch (SB) stand, a corsican pine (CP) stand and a pine stand with higher N deposition (CPN), and used the SWAP model (calibrated with PEST) for generating accurate water and matter fluxes. The input with precipitation was an important source of DON, but not for DOC. Release of DOC from the forest floor was minimally affected by forest type, but higher N deposition (CPN stand) caused an 82% increase of DOC release from the forest floor. Adsorption to mineral soil material rich in iron and/or aluminum oxyhydroxides was suggested to be the most important process removing DOC from the soil solution, responsible for substantial retention (67–84%) of DOC entering the mineral soil profile with forest floor leachate. Generally, DON was less reactive (i.e. less removal from the soil solution) than DOC, resulting in decreasing DOC/DON ratios with soil depth. We found increased DOC retention in the mineral soil as a result of higher N deposition (84 kg N ha−1 yr−1 additional DOC retention in CPN compared to CP). Overall DON leaching losses were 2.2, 3.3 and 5.0 kg N ha−1 yr−1 for SB, CP and CPN, respectively, contributing between 9–28% to total dissolved N (TDN) leaching. DON loss from SB and CP was not much higher than from unpolluted forests, and its relative contribution to TDN leaching was mainly determined by (large) differences in DIN leaching. The large TDN leaching losses are alarming, especially in the CPN stand that was N saturated.

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