DOM Biological Lability in an Estuarine System in Two Contrasting Periods

Estuarine processes play a key role in determining the amount and quality of land-derived dissolved organic matter (DOM) reaching the oceans. Microbial-mediated reactions can affect the concentration, quality, and bioavailability of DOM within an estuary. In this study, we investigated biological DOM removal in a small estuary and its variability in two contrasting seasons (spring and autumn) characterized by natural differences in the concentration and quality of the riverine DOM. Two incubation experiments were carried out using natural DOM and heterotrophic prokaryotes community collected at the estuary in March and September. Dissolved organic carbon (DOC) concentration, DOM fluorescence, and the heterotrophic prokaryotes abundance (HPA) showed marked differences between the two seasons. These parameters were followed through time for up to two months. Despite the marked differences in the initial conditions, the DOC removal rates were surprisingly similar in the two periods (16 µM DOC month−1 in March and 18 µM DOC month−1 in September), with the biggest removal in the first 48 h. The trend of fluorescent DOM (FDOM) during the incubation showed marked differences between the two periods. In March, the net removal of all the FDOM components was observed consistently with the decrease in DOC; whereas, in September, the net production of humic-like substances was observed.

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A global hotspot for dissolved organic carbon in hypermaritime watersheds of coastal British Columbia

Biogeosciences ◽

10.5194/bg-14-3743-2017 ◽

2017 ◽

Vol 14 (15) ◽

pp. 3743-3762 ◽

Cited By ~ 12

Author(s):

Allison A. Oliver ◽

Suzanne E. Tank ◽

Ian Giesbrecht ◽

Maartje C. Korver ◽

William C. Floyd ◽

...

Keyword(s):

British Columbia ◽

Organic Matter ◽

Organic Carbon ◽

Stream Water ◽

Coastal Ocean ◽

Stream Discharge ◽

Coastal Margin ◽

Doc Concentration ◽

Small Catchments ◽

Dom Composition

Abstract. The perhumid region of the coastal temperate rainforest (CTR) of Pacific North America is one of the wettest places on Earth and contains numerous small catchments that discharge freshwater and high concentrations of dissolved organic carbon (DOC) directly to the coastal ocean. However, empirical data on the flux and composition of DOC exported from these watersheds are scarce. We established monitoring stations at the outlets of seven catchments on Calvert and Hecate islands, British Columbia, which represent the rain-dominated hypermaritime region of the perhumid CTR. Over several years, we measured stream discharge, stream water DOC concentration, and stream water dissolved organic-matter (DOM) composition. Discharge and DOC concentrations were used to calculate DOC fluxes and yields, and DOM composition was characterized using absorbance and fluorescence spectroscopy with parallel factor analysis (PARAFAC). The areal estimate of annual DOC yield in water year 2015 was 33.3 Mg C km−2 yr−1, with individual watersheds ranging from an average of 24.1 to 37.7 Mg C km−2 yr−1. This represents some of the highest DOC yields to be measured at the coastal margin. We observed seasonality in the quantity and composition of exports, with the majority of DOC export occurring during the extended wet period (September–April). Stream flow from catchments reacted quickly to rain inputs, resulting in rapid export of relatively fresh, highly terrestrial-like DOM. DOC concentration and measures of DOM composition were related to stream discharge and stream temperature and correlated with watershed attributes, including the extent of lakes and wetlands, and the thickness of organic and mineral soil horizons. Our discovery of high DOC yields from these small catchments in the CTR is especially compelling as they deliver relatively fresh, highly terrestrial organic matter directly to the coastal ocean. Hypermaritime landscapes are common on the British Columbia coast, suggesting that this coastal margin may play an important role in the regional processing of carbon and in linking terrestrial carbon to marine ecosystems.

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Properties of Humic Acids in Meadow Soils Irrigated With the Slope-And Flooding System

10.21203/rs.3.rs-535526/v1 ◽

2021 ◽

Author(s):

Magdalena Banach-Szott ◽

Andrzej Dziamski

Keyword(s):

Particle Size ◽

Organic Matter ◽

Organic Carbon ◽

Humic Acids ◽

Soil Samples ◽

Hydrophobic Properties ◽

Irrigation Ditch ◽

Ft Ir ◽

Degree Of Maturity

Abstract The aim of the research has been to determine the effect of many-year irrigation of unique grasslands on the properties of humic acids defining the quality of organic matter. The research was performed based on the soil (Albic Brunic Arenosol, the A, AE and Bsv horizons) sampled from Europe’s unique complex of permanent grasslands irrigated continuously for 150 years, applying the slope-and-flooding system; the Czerskie Meadows. The soil samples were assayed for the content of total organic carbon (TOC) and the particle size distribution. HAs were extracted with the Schnitzer method and analysed for the elemental composition, spectrometric parameters in the UV-VIS range, hydrophilic and hydrophobic properties and the infrared spectra were produced. The research results have shown that the HAs properties depended on the depth and the distance from the irrigation ditch. The HAs of the A horizon of the soils were identified with a lower “degree of maturity”, as reflected by the values of atomic ratios (H/C, O/C, O/H), absorbance coefficients, and the FT-IR spectra, as compared with the HAs of the Bsv horizon. The HAs molecules of the soils sampled furthest from the irrigation ditch were identified with a higher degree of humification, as compared with the HAs of the soils sampled within the closest distance. The results have demonstrated that many-year grassland irrigation affected the structure and the properties of humic acids.

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Particulate organic matter composition and organic carbon flux in Arctic valley glaciers: examples from the Bayelva River and adjacent Kongsfjorden

Biogeosciences Discussions ◽

10.5194/bgd-12-15655-2015 ◽

2015 ◽

Vol 12 (18) ◽

pp. 15655-15685

Author(s):

Z.-Y. Zhu ◽

Y. Wu ◽

S.-M. Liu ◽

F. Wenger ◽

J. Hu ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Particulate Organic Matter ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Concentration Data ◽

Particulate Nitrogen ◽

Organic Carbon Flux ◽

Doc Concentration ◽

The Face

Abstract. In the face of ongoing global warming and glacier retreat, the composition and flux of organic matter in glacier–fjord systems are key variables for updating the carbon cycle and budget, whereas the role of Arctic valley glaciers seems unimportant when compared with the huge Greenland Ice Sheet. Our field observations of the glacier-fed Bayelva River, Svalbard, and the adjacent Kongsfjorden allowed us to determine the compositions of particulate organic matter from glacier to fjord and also to estimate the flux of organic carbon, both for the river and for Svalbard in general. Particulate organic carbon (POC) and dissolved organic carbon (DOC) in the Bayelva River averaged 56 and 73 μM, respectively, in August 2012. Amino acids (AAs) and phytoplankton pigments accounted for ~ 10 % of the particulate organic matter (POM) in the Bayelva River, while AAs represented > 90 % of particulate nitrogen in fjord surface water, suggesting the strong in situ assimilation of organic matter. Bacteria accounts for 13 and 19 % of the POC in the Bayelva River and the Kongsfjorden, respectively, while values for particulate nitrogen (PN) are much higher (i.e., 36 % in Kongsfjorden). The total discharge from the Bayelva River in 2012 was 29 × 106 m3. Furthermore, we calculated the annual POC, DOC, and PN fluxes for the river as 20 ± 1.6, 25 ± 5.6, and 4.7 ± 0.75 t, respectively. Using the POC content and DOC concentration data, we then estimated the annual POC and DOC fluxes for Svalbard glaciers. Although the estimated POC (0.056 ± 0.02 × 106 t yr−1) and DOC (0.02 ± 0.01 × 106 t yr−1) fluxes of Svalbard glaciers are small compared with those of the Greenland Ice Sheet, the area-weighted POC flux of Svalbard glaciers is twice that of the Greenland Ice Sheet, while the flux of DOC can be 4 to 7 times higher. Therefore, we propose that valley glaciers are efficient high-latitude sources of organic carbon.

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Transport and transformation of dissolved organic matter in the Neuse River estuarine system, NC, USA, following Hurricane Irene (2011)

Marine and Freshwater Research ◽

10.1071/mf15352 ◽

2016 ◽

Vol 67 (9) ◽

pp. 1313 ◽

Cited By ~ 5

Author(s):

Richard L. Miller ◽

Matthew M. Brown ◽

Ryan P. Mulligan

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Estuarine System ◽

Spectral Parameters ◽

Visible Absorption ◽

Neuse River ◽

Hurricane Irene ◽

Rain Events ◽

River Estuarine

Rivers are major conduits for the transport of allochthonous dissolved organic matter (DOM) to the ocean in coupled land–coastal systems. DOM can regulate biogeochemical processes and affect water quality, depending on the concentration and quality of DOM. By using spectral parameters calculated from chromophoric dissolved organic matter (CDOM) ultraviolet-visible absorption spectra, along with dissolved organic carbon (DOC) concentrations, we examined the input and change in the amount and quality of DOM in surface waters of the lower Neuse River and upper–middle regions of the Neuse Estuary following a major rainfall (30cm in 1 day) associated with Hurricane Irene (2011). CDOM and DOC nearly tripled in the 3 days following the storm. Although a strong linear relationship was observed between DOC and CDOM absorption coefficient at 350nm (R2=0.85), a higher fraction of non-chromophoric DOC to CDOM was observed during the rising river discharge. The spectral slope at 275–295nm and the slope ratio (275–295:350–400nm) indicated a shift from higher to lower molecular-weight DOM as it transited through the estuary, probably as a result of photodegradation. The present study demonstrated the utility of using CDOM spectral parameters for examining the flux and transformation of DOM in coastal waters following major rain events.

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Organic-matter quality of deep permafrost carbon – a study from Arctic Siberia

Biogeosciences ◽

10.5194/bg-12-2227-2015 ◽

2015 ◽

Vol 12 (7) ◽

pp. 2227-2245 ◽

Cited By ~ 46

Author(s):

J. Strauss ◽

L. Schirrmeister ◽

K. Mangelsdorf ◽

L. Eichhorn ◽

S. Wetterich ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Stable Carbon Isotopes ◽

Average Chain Length ◽

Frozen Ground ◽

Higher Plant ◽

Organic Matter Quality ◽

Microbial Decomposition ◽

Geochemical Parameters

Abstract. The organic-carbon (OC) pool accumulated in Arctic permafrost (perennially frozen ground) equals the carbon stored in the modern atmosphere. To give an idea of how Yedoma region permafrost could respond under future climatic warming, we conducted a study to quantify the organic-matter quality (here defined as the intrinsic potential to be further transformed, decomposed, and mineralized) of late Pleistocene (Yedoma) and Holocene (thermokarst) deposits on the Buor-Khaya Peninsula, northeast Siberia. The objective of this study was to develop a stratigraphic classified organic-matter quality characterization. For this purpose the degree of organic-matter decomposition was estimated by using a multiproxy approach. We applied sedimentological (grain-size analyses, bulk density, ice content) and geochemical parameters (total OC, stable carbon isotopes (δ13C), total organic carbon : nitrogen (C / N) ratios) as well as lipid biomarkers (n-alkanes, n-fatty acids, hopanes, triterpenoids, and biomarker indices, i.e., average chain length, carbon preference index (CPI), and higher-plant fatty-acid index (HPFA)). Our results show that the Yedoma and thermokarst organic-matter qualities for further decomposition exhibit no obvious degradation–depth trend. Relatively, the C / N and δ13C values and the HPFA index show a significantly better preservation of the organic matter stored in thermokarst deposits compared to Yedoma deposits. The CPI data suggest less degradation of the organic matter from both deposits, with a higher value for Yedoma organic matter. As the interquartile ranges of the proxies mostly overlap, we interpret this as indicating comparable quality for further decomposition for both kinds of deposits with likely better thermokarst organic-matter quality. Supported by principal component analyses, the sediment parameters and quality proxies of Yedoma and thermokarst deposits could not be unambiguously separated from each other. This revealed that the organic-matter vulnerability is heterogeneous and depends on different decomposition trajectories and the previous decomposition and preservation history. Elucidating this was one of the major new contributions of our multiproxy study. With the addition of biomarker data, it was possible to show that permafrost organic-matter degradation likely occurs via a combination of (uncompleted) degradation cycles or a cascade of degradation steps rather than as a linear function of age or sediment facies. We conclude that the amount of organic matter in the studied sediments is high for mineral soils and of good quality and therefore susceptible to future decomposition. The lack of depth trends shows that permafrost acts like a giant freezer, preserving the constant quality of ancient organic matter. When undecomposed Yedoma organic matter is mobilized via thermokarst processes, the fate of this carbon depends largely on the environmental conditions; the carbon could be preserved in an undecomposed state till refreezing occurs. If modern input has occurred, thermokarst organic matter could be of a better quality for future microbial decomposition than that found in Yedoma deposits.

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Bacterial enzymatic activity and bioavailability of heavy metals in sediments from Boa Viagem Beach (Guanabara Bay)

Anuário do Instituto de Geociências - UFRJ ◽

10.11137/2003_0_60-68 ◽

2003 ◽

Vol 26 ◽

pp. 60-68

Author(s):

Mirian Crapez ◽

José Antonio Baptista Neto ◽

M. G. S. Bispo

Keyword(s):

Heavy Metals ◽

Organic Matter ◽

Organic Carbon ◽

Bacterial Count ◽

Total Bacterial Count ◽

Carbon Turnover ◽

Guanabara Bay ◽

Organic Matter Quality ◽

Number Of Bacteria

This study focuses on the quality of the organic matter that reaches the sediment from Boa Viagem Beach and through the evaluation of the total bacterial count, the electron transport system activity (ETSA), the esterase activity (EST), as well as the protein and the organic matter contents. Seasonal variations of organic matter, protein content and the number of bacteria were particularly notable in the summer. ETSA reached a maximum of 7.48 Âµl O2 h-1 g-1 in the summer. EST activity presented a different pattern once it reached a maximum of 0.17 Âµg fluorescein h-1 g-1 in the winter. The temporal variation of ETSA and EST activity indicated that biopolymers predominated in the winter, and oligomers or monomers predominated in the summer. These results suggest that organic carbon turnover is more likely to be controlled by organic matter quality. The heavy metals concentrations, especially for Cu, Zn, Ni and Cr, indicated absence of the inhibition of dehydrogenase activity, and they are not bioavailable in the EC50 values

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Seasonal Changes in Dissolved Organic Matter Composition in a Patagonian Fjord Affected by Glacier Melt Inputs

Frontiers in Marine Science ◽

10.3389/fmars.2021.612386 ◽

2021 ◽

Vol 8 ◽

Author(s):

Matthew G. Marshall ◽

Anne M. Kellerman ◽

Jemma L. Wadham ◽

Jon R. Hawkings ◽

Giovanni Daneri ◽

...

Keyword(s):

Organic Matter ◽

Surface Layer ◽

Organic Carbon ◽

Dissolved Organic Matter ◽

Relative Contribution ◽

Glacier Melt ◽

Level Data ◽

Chilean Patagonia ◽

Doc Concentration ◽

Dom Composition

Biogeochemical processes in fjords are likely affected by changes in surrounding glacier cover but very little is known about how meltwater directly influences dissolved organic matter (DOM) in fjords. Moreover, the data available are restricted to a handful of northern hemisphere sites. Here we analyze seasonal and spatial variation in dissolved organic carbon (DOC) concentration and DOM composition (spectrofluorescence, ultrahigh resolution mass spectrometry) in Baker-Martinez Fjord, Chilean Patagonia (48°S), to infer the impacts of rapid regional deglaciation on fjord DOM. We show that surface layer DOC concentrations do not vary significantly between seasons, but DOM composition is sensitive to differences in riverine inputs. In summer, higher protein-like fluorescence reflects increased glacial meltwater inputs, whilst molecular level data show weaker influence from marine DOM due to more intense stratification. We postulate that the shifting seasonal balance of riverine and marine waters affects the supply of biolabile peptides and organic nitrogen cycling in the surface layer. Trends in DOM composition with increasing salinity are consistent with patterns in estuaries (i.e. preferential removal of aromatic compounds and increasing relative contribution of unsaturated and heteroatom-rich DOM from marine sources). Preliminary estimates also suggest that at least 10% of the annual organic carbon stock in this fjord is supplied by the four largest, glacially fed rivers and that these inputs are dominated by dissolved (84%) over particulate organic carbon. Riverine DOC may therefore be an important carbon subsidy to bacterial communities in the inner fjord. The overall findings highlight the biogeochemical sensitivity of a Patagonian fjord to changes in glacier melt input, which likely has relevance for other glaciated fjords in a warming climate.

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Humus transformation at the bank filtration water plant

Water Science & Technology ◽

10.2166/wst.1994.0526 ◽

1994 ◽

Vol 30 (10) ◽

pp. 179-187 ◽

Cited By ~ 28

Author(s):

I. T. Miettinen ◽

P. J. Martikainen ◽

T. Vartiainen

Keyword(s):

Organic Matter ◽

Surface Water ◽

Organic Carbon ◽

Chemical Oxygen Demand ◽

Total Organic Carbon ◽

Lake Water ◽

Oxygen Demand ◽

Bank Filtration ◽

Water Plant

Transformations in the amount and quality of organic matter (humus) during bank filtration of surface water were studied by analyzing the changes in total organic carbon (TOC), non-purgeable organic carbon (NPOC), chemical oxygen demand (COD), color of water, and UV absorbing humus fractions. The amount of organic matter expressed as TOC, NPOC, and COD depended on temperature and filtration distance from lake water. The color of water and the UV absorbing humus peaks presenting different humus molecule fractions decreased more effectively than other parameters measuring the amount of organic matter in water. The ratio of COD to TOC decreased when the filtration distance of water increased. Our observations indicated that bank filtration of humus-rich lake water changed more the quality of organic matter than its total amount.

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The non-conservative distribution pattern of organic matter in Rajang, a tropical river with peatland in its estuary

10.5194/bg-2019-157 ◽

2019 ◽

Cited By ~ 1

Author(s):

Zhuoyi Zhu ◽

Joanne Oakes ◽

Bradley Eyre ◽

Youyou Hao ◽

Edwin Sien Aun Sia ◽

...

Keyword(s):

Amino Acids ◽

Organic Matter ◽

Organic Carbon ◽

Dissolved Organic Matter ◽

Anthropogenic Activities ◽

Field Investigation ◽

Organic Matter Composition ◽

Doc Concentration ◽

Nitrogen Ratio ◽

Export Pattern

Abstract. South-east Asian peatland-draining rivers have attracted much attention due to their high dissolved organic carbon (DOC) yield and high CO2 emissions under anthropogenic activities. In August 2016, we carried out a field investigation of the Rajang river and estuary, a tropical system located in Sarawak, Malaysia. The Rajang has peatland in its estuary while the river basin is covered by tropical rainforest. DOC δ13C in the Rajang ranged from −28.7 ‰ to −20.1 ‰ and a U-shaped trend from river to estuary was identified. For particulate organic carbon (POC), the δ13C ranged between −29.4 ‰ to −31.1 ‰ in the river and a clear increasing trend towards more δ13C -enriched with higher salinity existed in the estuary. In the estuary, there was a linear conservative dilution pattern for dissolved organic matter composition (as quantified by D/L amino acids enantiomers) plotted against DOC δ13C, whereas when plotted against salinity dissolved D/L amino acids enantiomers values were higher than the theoretical dilution value. Together, these data indicate that the addition of DOC in estuary (by peatland) not only increased the DOC concentration, but also altered its composition, by adding more bio-degraded, 13C-depleted organic matter into the bulk dissolved organic matter. Alteration of organic matter composition (adding of more degraded subpart) was also apparent for the particulate phase, but patterns were less clear. The Rajang was characterized by DOC / DON ratios of 50 in the river section, with loss of DON in the estuary increased the ratio to 140, suggesting the unbalanced export pattern for organic carbon and nitrogen, respectively. Under anthropogenic activities, further assessment of organic carbon to nitrogen ratio is needed.

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Influence of Dissolved Organic Matter Sources on In-Stream Net Dissolved Organic Carbon Uptake in a Mediterranean Stream

Water ◽

10.3390/w12061722 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1722 ◽

Cited By ~ 2

Author(s):

Anna Lupon ◽

Núria Catalán ◽

Eugènia Martí ◽

Susana Bernal

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Dissolved Organic Matter ◽

Dissolved Organic Carbon ◽

Leaf Litter ◽

Natural Conditions ◽

Mediterranean Stream ◽

Doc Concentration ◽

The Relationship ◽

Different Sources

Studies exploring how different sources of dissolved organic matter (DOM) influence in-stream dissolved organic carbon (DOC) uptake at the ecosystem scale are scarce in the literature. To fill this knowledge gap, we examined the relationship between DOM sources and in-stream net DOC uptake (UDOC) in a sub-humid Mediterranean stream. We considered four reach-scale scenarios occurring under natural conditions that differed in predominant DOM sources (groundwater, leaf litter, and/or upstream water). Results showed that groundwater inputs favored in-stream net DOC uptake, while leaf litter inputs promoted in-stream net DOC release. However, there was no clear effect of DOM source mixing on the magnitude of UDOC. Further, the variability in UDOC within and among scenarios was mostly explained by stream DOC concentration, suggesting that DOC availability limits microbial activity in this stream. DOM composition became a controlling factor of UDOC variability only during the leaf litter period, when stream DOC concentration was the highest. Together, these results suggest that the capacity of headwater forested streams to process DOC is closely tied to the availability of different DOM sources and how they vary over time and along the river network.

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