Colour - mass balances and colour - dissolved organic carbon relationships in lakes and streams in central Ontario

Colour and dissolved organic carbon (DOC) concentrations and mass balances were measured for seven unproductive lakes and 20 tributary streams between June 1980 and May 1992. Individual observations of colour, which measures an unknown DOC fraction assumed to be principally humic, were not good predictors of discrete DOC concentrations for any of the study sites. Long-term mean colour was, however, strongly correlated with long-term mean DOC concentrations in streams and lakes. Colour behaved differently from the total DOC pool in lakes. Lake retention and loss coefficients for colour were always higher than corresponding values for the total DOC pool, and the mean annual colour/DOC ratios in lake outflows were always less than the corresponding ratios in lake inputs, indicating that the coloured fraction was preferentially removed or photooxidized. A steady-state mass balance model was used to estimate the upper bound for the average coloured fraction of DOC in each lake. The upper bound for the seven lakes ranged from 34 to 88%, increasing with increasing colour, DOC, and total phosphorus.

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The dynamics and export of dissolved organic carbon from subtropical small mountainous rivers during typhoon and non-typhoon periods

10.5194/bg-2017-105 ◽

2017 ◽

Cited By ~ 1

Author(s):

Tsung-Yu Lee ◽

Li-Chin Lee ◽

Jr-Chuan Huang ◽

Shih-Hao Jien ◽

Thomas Hein ◽

...

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Water Discharge ◽

Dilution Effect ◽

Carbon Export ◽

Doc Concentration ◽

The Mean ◽

Doc Flux ◽

Small Mountainous Rivers

Abstract. Small mountainous rivers (SMRs) are important conveyors of the land-to-ocean organic carbon export. However, relatively few studies have focused on dissolved organic carbon (DOC) compared to particulate organic carbon. In a long-term project (2002 to 2014), stream DOC was monitored in three neighboring subtropical small mountainous rivers of Taiwan. The objective was to relate DOC concentrations to water discharge and to quantify DOC flux during typhoon and non-typhoon periods. Seasonal fluctuations of DOC concentrations were closely correlated with air temperature at all sampling stations. During non-typhoon periods, increasing water discharge led to decreasing DOC concentrations due to a dilution effect. However, during typhoon periods, DOC concentrations increased with some lead time along the hydrograph and reached the annual maximum which likely sources from a significant input of litter and upper soil layers. The mean DOC concentration of the studied systems (

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Long-term stability of marine dissolved organic carbon emerges from a neutral network of compounds and microbes

Scientific Reports ◽

10.1038/s41598-019-54290-z ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 7

Author(s):

A. Mentges ◽

C. Feenders ◽

C. Deutsch ◽

B. Blasius ◽

T. Dittmar

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Deep Sea ◽

Mechanistic Model ◽

Term Stability ◽

Long Term Stability ◽

Heterotrophic Microorganisms ◽

Wide Range ◽

The Mean

AbstractDissolved organic carbon (DOC) is the main energy source for marine heterotrophic microorganisms, but a small fraction of DOC resists microbial degradation and accumulates in the ocean. The reason behind this recalcitrance is unknown. We test whether the long-term stability of DOC requires the existence of structurally refractory molecules, using a mechanistic model comprising a diverse network of microbe-substrate interactions. Model experiments reproduce three salient observations, even when all DOC compounds are equally degradable: (i) >15% of an initial DOC pulse resists degradation, but is consumed by microbes if concentrated, (ii) the modelled deep-sea DOC reaches stable concentrations of 30–40 mmolC/m3, and (iii) the mean age of deep-sea DOC is several times the age of deep water with a wide range from <100 to >10,000 years. We conclude that while structurally-recalcitrant molecules exist, they are not required in the model to explain either the amount or longevity of DOC.

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Effect of Acidified Versus Frozen Storage on Marine Dissolved Organic Carbon Concentration and Isotopic Composition

Radiocarbon ◽

10.1017/rdc.2016.48 ◽

2016 ◽

Vol 59 (3) ◽

pp. 843-857 ◽

Cited By ~ 6

Author(s):

Brett D Walker ◽

Sheila Griffin ◽

Ellen R M Druffel

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Standard Procedure ◽

Frozen Storage ◽

Open Ocean ◽

Field Collection ◽

Organic Carbon Concentration ◽

Large Numbers ◽

Logistical Problem

AbstractThe standard procedure for storing/preserving seawater dissolved organic carbon (DOC) samples after field collection is by freezing (–20°C) until future analysis can be made. However, shipping and receiving large numbers of these samples without thawing presents a significant logistical problem and large monetary expense. Access to freezers can also be limited in remote field locations. We therefore test an alternative method of preserving and storing samples for the measurement of DOC concentrations ([DOC]), stable carbon (δ13C), and radiocarbon (as ∆14C) isotopic values via UV photooxidation (UVox). We report a total analytical reproducibility of frozen DOC samples to be [DOC]±1.3 µM, ∆14C±9.4‰, and δ13C±0.1‰, comparable to previously reported results (Druffel et al. 2013). Open Ocean DOC frozen versus acidified duplicates were on average offset by ∆DOC±1.1 µM, ∆∆14C± –1.3‰, and ∆δ13C± –0.1‰. Coastal Ocean frozen vs. acidified sample replicates, collected as part of a long-term (380-day) storage experiment, had larger, albeit consistent offsets of ∆DOC±2.2 µM, ∆∆14C±1.5‰, and ∆δ13C± –0.2‰. A simple isotopic mass balance of changes in [DOC], ∆14C, and δ13C values reveals loss of semi-labile DOC (2.2±0.6 µM, ∆14C=–94±105‰, δ13C=–27±10‰; n=4) and semi-recalcitrant DOC (2.4±0.7 µM, ∆14C=–478±116‰, δ13C=–23.4±3.0‰; n=3) in Coastal and Open Ocean acidified samples, respectively.

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Effect of long-term phosphorus addition on the quantity and quality of dissolved organic carbon in a freshwater wetland of Northeast China

The Science of The Total Environment ◽

10.1016/j.scitotenv.2017.02.084 ◽

2017 ◽

Vol 586 ◽

pp. 1032-1037 ◽

Cited By ~ 6

Author(s):

Rong Mao ◽

Si-Yue Li ◽

Xin-Hou Zhang ◽

Xian-Wei Wang ◽

Chang-Chun Song

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Northeast China ◽

Freshwater Wetland ◽

Phosphorus Addition

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The mass balance of McCall Glacier, Brooks Range, Alaska, U.S.A.; its regional relevance and implications for climate change in the Arctic

Journal of Glaciology ◽

10.3189/s0022143000002665 ◽

1998 ◽

Vol 44 (147) ◽

pp. 333-351 ◽

Cited By ~ 1

Author(s):

B.T. Rabus ◽

K. A. Echelmeyer

Keyword(s):

Mass Balance ◽

The Arctic ◽

Balance Model ◽

Mass Balances ◽

Arctic Alaska ◽

Low Mass ◽

Length Changes ◽

Arctic Glacier ◽

Long Term Trend

AbstractMcCall Glacier has the only long-term mass-balance record in Arctic-Alaska. Average annual balances over the periods 1958–72 and 1972–93 were –15 and –33cm, respectively; recent annual balances (1993–96) are about –60 cm, and the mass-balance gradient has increased. For an Arctic glacier, with its low mass-exchange rate, this marks a significant negative trend.Recently acquired elevation profiles of McCall Glacier and ten other glaciers within a 30 km radius were compared with topographic maps made in 1956 or 1973. Most of these glaciers had average annual mass balances between –25 and –33 cm, while McCall Glacier averaged –28 cm for 1956–93, indicating that it is representative of the region. In contrast, changes in terminus position for the different glaciers vary markedly. Thus, mass-balance trends in this region cannot be estimated from fractional length changes at time-scales of a few decades.We developed a simple degree-day/accumulation mass-balance model for McCall Glacier. The model was tested using precipitation and radiosonde temperatures from weather stations at Inuvik, Canada, and Barrow, Kaktovik and Fairbanks, Alaska, and was calibrated with the measured balances. The Inuvik data reproduce all measured mass balances of McCall Glacier well and also reproduce the long-term trend towards more negative balances. Data from the other stations do not produce satisfactory model results. We speculate that the Arctic Front, oriented east–west in this region, causes the differences in model results.

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Potential for long‐term transfer of dissolved organic carbon from riparian zones to streams in boreal catchments

Global Change Biology ◽

10.1111/gcb.12872 ◽

2015 ◽

Vol 21 (8) ◽

pp. 2963-2979 ◽

Cited By ~ 45

Author(s):

José L. J. Ledesma ◽

Thomas Grabs ◽

Kevin H. Bishop ◽

Sherry L. Schiff ◽

Stephan J. Köhler

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Riparian Zones

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Dissolved organic carbon and dissolved nitrogen in soil under different fertilization treatments

Plant Soil and Environment ◽

10.17221/3346-pse ◽

2011 ◽

Vol 52 (No. 2) ◽

pp. 55-63 ◽

Cited By ~ 19

Author(s):

S.S. Gonet ◽

B. Debska

Keyword(s):

Surface Layer ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Cattle Slurry ◽

Soil Horizons ◽

Mineral Fertilization ◽

Labile Organic Matter ◽

Dissolved Nitrogen ◽

After Effect

The objective of the study was to evaluate the effects of long-term fertilization of a sandy soil with differentiated doses of cattle slurry as well as its after-effect action on the possibilities of migration of dissolved organic carbon (DOC) and dissolved nitrogen (DNt) down to deeper layers of the soil profile. DOC and DNt were extracted with borate buffer and 0.004M CaCl<sub>2</sub> solution. Evaluation of effects of cattle slurry on the content of DOC and DNt was done in comparison with mineral fertilization. It was shown that the use of cattle slurry in the doses of 100 and 200 m<sup>3</sup>/ha caused a significant increase of labile organic matter in the 0–25 and 25–50 cm layers of soil. As compared with mineral fertilization the application of slurry increased also the amounts of extracted DNt, but only in the surface layer. The DNt content in the deeper soil horizons did not depend on the kind of fertilization. Concentrations of DOC and DNt in the extracts depended not only on their content in soil but it was also modified substantially by the extractant used.

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