scholarly journals Wildfire-Derived Pyrogenic Carbon Modulates Organic Matter and Microbial Functioning in a Fluvial Ecosystem

2021 ◽  
Author(s):  
Lukas Thuile Bistarelli ◽  
Caroline Poyntner ◽  
Cristina Santín ◽  
Stefan H. Doerr ◽  
Matthew V. Talluto ◽  
...  
Keyword(s):  
Organic Matter ◽  
Freshwater Ecosystems ◽  
Enzymatic Activities ◽  
Pyrogenic Carbon ◽  
Microbial Biofilms ◽  
Doc Concentration ◽  
Research Gap ◽  
Fluvial Ecosystem ◽  
In Fire ◽  
Dom Composition

Wildfires produce large amounts of pyrogenic carbon (PyC), including particulate charcoal, known for its chemical recalcitrance and sorption affinity for organic molecules. Wildfire-derived PyC is highly mobile in the landscape and can be transported to fluvial networks where it may impact natural dissolved organic matter (DOM) and microbial biofilms. The effects of PyC on freshwater ecosystems and carbon cycling therein remain poorly investigated. To address this research gap, we used in-stream flumes with a control vs treatment design (pulse addition of PyC particles). We present evidence that field-aged PyC inputs into river ecosystems can alter dissolved organic carbon (DOC) concentration, DOM composition, pH, and enzymatic activities in benthic biofilms. In stream DOM composition was altered due to leaching of pyrogenic DOM from PyC and possible concurrent sorption of riverine DOM to PyC. DOM changes and increase in pH were associated with changes in enzymatic activities, which reflected preferential usageof recalcitrant over easily available DOM by biofilms. Furthermore, we observed particulate PyC sedimentation on biofilm surfaces, which may further modulate the impacts of PyC. This study highlights the importance of PyC for in-stream DOM propertiesand biofilm functioning with implications for in-stream biogeochemical cycling in fire affected watersheds. <br>

scholarly journals Wildfire-Derived Pyrogenic Carbon Modulates Organic Matter and Microbial Functioning in a Fluvial Ecosystem

2021 ◽  
Author(s):  
Lukas Thuile Bistarelli ◽  
Caroline Poyntner ◽  
Cristina Santín ◽  
Stefan H. Doerr ◽  
Matthew V. Talluto ◽  
...  
Keyword(s):  
Organic Matter ◽  
Freshwater Ecosystems ◽  
Enzymatic Activities ◽  
Pyrogenic Carbon ◽  
Microbial Biofilms ◽  
Doc Concentration ◽  
Research Gap ◽  
Fluvial Ecosystem ◽  
In Fire ◽  
Dom Composition

Wildfires produce large amounts of pyrogenic carbon (PyC), including particulate charcoal, known for its chemical recalcitrance and sorption affinity for organic molecules. Wildfire-derived PyC is highly mobile in the landscape and can be transported to fluvial networks where it may impact natural dissolved organic matter (DOM) and microbial biofilms. The effects of PyC on freshwater ecosystems and carbon cycling therein remain poorly investigated. To address this research gap, we used in-stream flumes with a control vs treatment design (pulse addition of PyC particles). We present evidence that field-aged PyC inputs into river ecosystems can alter dissolved organic carbon (DOC) concentration, DOM composition, pH, and enzymatic activities in benthic biofilms. In stream DOM composition was altered due to leaching of pyrogenic DOM from PyC and possible concurrent sorption of riverine DOM to PyC. DOM changes and increase in pH were associated with changes in enzymatic activities, which reflected preferential usageof recalcitrant over easily available DOM by biofilms. Furthermore, we observed particulate PyC sedimentation on biofilm surfaces, which may further modulate the impacts of PyC. This study highlights the importance of PyC for in-stream DOM propertiesand biofilm functioning with implications for in-stream biogeochemical cycling in fire affected watersheds. <br>

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

2017 ◽  
Vol 14 (15) ◽  
pp. 3743-3762 ◽  
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.

scholarly journals Assessing the Contribution of Seasonality, Tides, and Microbial Processing to Dissolved Organic Matter Composition Variability in a Southeastern U.S. Estuary

2021 ◽  
Vol 8 ◽  
Author(s):  
Rachel P. Martineac ◽  
Alexey V. Vorobev ◽  
Mary Ann Moran ◽  
Patricia M. Medeiros
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Critical Role ◽  
Bacterial Cells ◽  
Secondary Importance ◽  
Relative Contribution ◽  
Doc Concentration ◽  
Compositional Changes ◽  
Dom Composition

Uncovering which biogeochemical processes have a critical role controlling dissolved organic matter (DOM) compositional changes in complex estuarine environments remains a challenge. In this context, the aim of this study is to characterize the dominant patterns of variability modifying the DOM composition in an estuary off the Southeastern U.S. We collected water samples during three seasons (July and October 2014 and April 2015) at both high and low tides and conducted short- (1 day) and long-term (60 days) dark incubations. Samples were analyzed for bulk DOC concentration, and optical (CDOM) and molecular (FT-ICR MS) compositions and bacterial cells were collected for metatranscriptomics. Results show that the dominant pattern of variability in DOM composition occurs at seasonal scales, likely associated with the seasonality of river discharge. After seasonal variations, long-term biodegradation was found to be comparatively more important in the fall, while tidal variability was the second most important factor correlated to DOM composition in spring, when the freshwater content in the estuary was high. Over shorter time scales, however, the influence of microbial processing was small. Microbial data revealed a similar pattern, with variability in gene expression occurring primarily at the seasonal scale and tidal influence being of secondary importance. Our analyses suggest that future changes in the seasonal delivery of freshwater to this system have the potential to significantly impact DOM composition. Changes in residence time may also be important, helping control the relative contribution of tides and long-term biodegradation to DOM compositional changes in the estuary.

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

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.

scholarly journals How humans alter dissolved organic matter composition in freshwater: relevance for the Earth’s biogeochemistry

2021 ◽  
Author(s):  
Marguerite A. Xenopoulos ◽  
Rebecca T. Barnes ◽  
Kyle S. Boodoo ◽  
David Butman ◽  
Núria Catalán ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Drinking Water ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Global Climate ◽  
Chemical Properties ◽  
Freshwater Ecosystems ◽  
Biogeochemical Processes ◽  
Dom Composition

AbstractDissolved organic matter (DOM) is recognized for its importance in freshwater ecosystems, but historical reliance on DOM quantity rather than indicators of DOM composition has led to an incomplete understanding of DOM and an underestimation of its role and importance in biogeochemical processes. A single sample of DOM can be composed of tens of thousands of distinct molecules. Each of these unique DOM molecules has their own chemical properties and reactivity or role in the environment. Human activities can modify DOM composition and recent research has uncovered distinct DOM pools laced with human markers and footprints. Here we review how land use change, climate change, nutrient pollution, browning, wildfires, and dams can change DOM composition which in turn will affect internal processing of freshwater DOM. We then describe how human-modified DOM can affect biogeochemical processes. Drought, wildfires, cultivated land use, eutrophication, climate change driven permafrost thaw, and other human stressors can shift the composition of DOM in freshwater ecosystems increasing the relative contribution of microbial-like and aliphatic components. In contrast, increases in precipitation may shift DOM towards more relatively humic-rich, allochthonous forms of DOM. These shifts in DOM pools will likely have highly contrasting effects on carbon outgassing and burial, nutrient cycles, ecosystem metabolism, metal toxicity, and the treatments needed to produce clean drinking water. A deeper understanding of the links between the chemical properties of DOM and biogeochemical dynamics can help to address important future environmental issues, such as the transfer of organic contaminants through food webs, alterations to nitrogen cycling, impacts on drinking water quality, and biogeochemical effects of global climate change.

scholarly journals When Forests Take Over After Land Abandonment: Dissolved Organic Matter Response in Headwater Mountain Streams

2021 ◽  
Vol 3 ◽  
Author(s):  
Edurne Estévez ◽  
Jose M. Álvarez-Martínez ◽  
Thorsten Dittmar ◽  
José Barquín ◽  
Gabriel Singer
Keyword(s):  
Organic Matter ◽  
Land Cover ◽  
Dissolved Organic Matter ◽  
Soil Properties ◽  
Forest Cover ◽  
Secondary Forest ◽  
Freshwater Ecosystems ◽  
Mountain Streams ◽  
Land Cover Changes ◽  
Dom Composition

Dissolved organic matter (DOM) represents the largest pool of organic carbon in fluvial ecosystems. The majority of DOM in rivers is of terrigenous origin—making DOM composition highly dependent on vegetation cover and soil properties. While deforestation is still a worldwide anthropogenic phenomenon, current land cover change in temperate regions is often characterized by secondary succession processes following the abandonment of agricultural activities including grazing on pasturelands. This results in (secondary) forest expansion with a consequent, time-lagged transformation of soil properties. Predicting the time scale and spatial scale (i.e., location in the catchment: riparian vs. upslope areas) at which such land cover changes affect the terrestrial-aquatic carbon linkage and concomitantly alter properties of fluvial DOM as drivers of carbon cycling in freshwater ecosystems represents a new scientific challenge. In an attempt to identify potential legacy effects of land cover, i.e., reaction delays of fluvial DOM to changes in land cover, we here investigate the influence of specific current and historic (2 decade-old) land cover types on molecularly resolved fluvial DOM composition in headwater mountain streams. Our analysis is based on a scale-sensitive approach weighing in the distance of land cover (changes) to the stream and ultrahigh-resolution mass spectrometric analyses. Results identified the dominance of terrigenous DOM, with phenolic and polyphenolic sum formulae commonly associated to lignins and tannins, in all the studied streams. DOM properties mostly reflected present-day gradients of forest cover in the riparian area. In more forested catchments, DOM had on average higher molecular weight and a greater abundance of O-rich phenols and polyphenols but less aliphatics. Besides the modulation of the DOM source, our results also point to an important influence of photodegradation associated to variation in light exposition with riparian land cover in defining fluvial DOM properties. Despite expectations, we were unable to detect an effect of historic land cover on present-day DOM composition, at least at the investigated baseflow conditions, probably because of an overriding effect of current riparian vegetation.

scholarly journals Globally significant yields of dissolved organic carbon from small watersheds of the Pacific coastal temperate rainforest

2017 ◽  
Author(s):  
Allison A. Oliver ◽  
Suzanne E. Tank ◽  
Ian Giesbrecht ◽  
Maartje C. Korver ◽  
William C. Floyd ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Stream Water ◽  
Coastal Ocean ◽  
Temperate Rainforest ◽  
The Pacific ◽  
Doc Concentration ◽  
Small Catchments ◽  
Outer Coast ◽  
Dom Composition

Abstract. The perhumid region of the Pacific coastal temperate rainforest of North America (PCTR) 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 is scarce. We established monitoring stations at the outlets of seven catchments on Calvert and Hecate Islands, British Columbia, which represent the rain dominated outer-coast region of the PCTR. 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 examined using absorbance and fluorescence spectroscopy, including 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 24.1–37.7 Mg C km−2 yr−1. This represents some of the highest DOC yields in the world exported to the ocean. We observed strong seasonality in the quantity and composition of exports, with the majority of DOC export occurring during the extended wet period of the year (September–April). Stream flow from catchments reacted quickly to rain inputs, resulting in rapid flushing of relatively fresh, highly terrestrial-like DOM. DOC concentration and measures of DOM composition were correlated with watershed attributes, including the extent of lakes and wetlands, and thickness of organic and mineral soils. Our discovery of high DOC yields from these small catchments on the outer-coast of the temperate rainforest is especially compelling as they represent the delivery of relatively fresh, highly terrestrial organic matter directly to the coastal ocean. This suggests that this coastal margin may play an important role in the global processing of carbon and in linking terrestrial carbon to marine ecosystems.

scholarly journals The river as a chemostat: fresh perspectives on dissolved organic matter flowing down the river continuum

2015 ◽  
Vol 72 (8) ◽  
pp. 1272-1285 ◽  
Author(s):  
Irena F. Creed ◽  
Diane M. McKnight ◽  
Brian A. Pellerin ◽  
Mark B. Green ◽  
Brian A. Bergamaschi ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
The United States ◽  
Biogeochemical Processes ◽  
River Continuum ◽  
The Us ◽  
Doc Concentration ◽  
Continuum Concept ◽  
Temporal Homogenization ◽  
Dom Composition

A better understanding is needed of how hydrological and biogeochemical processes control dissolved organic carbon (DOC) concentrations and dissolved organic matter (DOM) composition from headwaters downstream to large rivers. We examined a large DOM dataset from the National Water Information System of the US Geological Survey, which represents approximately 100 000 measurements of DOC concentration and DOM composition at many sites along rivers across the United States. Application of quantile regression revealed a tendency towards downstream spatial and temporal homogenization of DOC concentrations and a shift from dominance of aromatic DOM in headwaters to more aliphatic DOM downstream. The DOC concentration–discharge (C-Q) relationships at each site revealed a downstream tendency towards a slope of zero. We propose that despite complexities in river networks that have driven many revisions to the River Continuum Concept, rivers show a tendency towards chemostasis (C-Q slope of zero) because of a downstream shift from a dominance of hydrologic drivers that connect terrestrial DOM sources to streams in the headwaters towards a dominance of instream and near-stream biogeochemical processes that result in preferential losses of aromatic DOM and preferential gains of aliphatic DOM.

scholarly journals DOM degradation by light and microbes along the Yukon River-coastal ocean continuum

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Brice K. Grunert ◽  
Maria Tzortziou ◽  
Patrick Neale ◽  
Alana Menendez ◽  
Peter Hernes
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Salinity Gradient ◽  
Coastal Ocean ◽  
Interactive Effects ◽  
The Arctic ◽  
Yukon River ◽  
Spring Freshet ◽  
Dom Composition

AbstractThe Arctic is experiencing rapid warming, resulting in fundamental shifts in hydrologic connectivity and carbon cycling. Dissolved organic matter (DOM) is a significant component of the Arctic and global carbon cycle, and significant perturbations to DOM cycling are expected with Arctic warming. The impact of photochemical and microbial degradation, and their interactive effects, on DOM composition and remineralization have been documented in Arctic soils and rivers. However, the role of microbes, sunlight and their interactions on Arctic DOM alteration and remineralization in the coastal ocean has not been considered, particularly during the spring freshet when DOM loads are high, photoexposure can be quite limited and residence time within river networks is low. Here, we collected DOM samples along a salinity gradient in the Yukon River delta, plume and coastal ocean during peak river discharge immediately after spring freshet and explored the role of UV exposure, microbial transformations and interactive effects on DOM quantity and composition. Our results show: (1) photochemical alteration of DOM significantly shifts processing pathways of terrestrial DOM, including increasing relative humification of DOM by microbes by > 10%; (2) microbes produce humic-like material that is not optically distinguishable from terrestrial humics; and (3) size-fractionation of the microbial community indicates a size-dependent role for DOM remineralization and humification of DOM observed through modeled PARAFAC components of fluorescent DOM, either through direct or community effects. Field observations indicate apparent conservative mixing along the salinity gradient; however, changing photochemical and microbial alteration of DOM with increasing salinity indicate changing DOM composition likely due to microbial activity. Finally, our findings show potential for rapid transformation of DOM in the coastal ocean from photochemical and microbial alteration, with microbes responsible for the majority of dissolved organic matter remineralization.

scholarly journals Mechanical signatures of microbial biofilms in micropillar-embedded growth chambers

Soft Matter ◽  
2016 ◽  
Vol 12 (23) ◽  
pp. 5224-5232 ◽  
Author(s):  
S. C. Chew ◽  
B. Kundukad ◽  
W. K. Teh ◽  
P. Doyle ◽  
L. Yang ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Organic Matter ◽  
Microbial Biofilms ◽  
Growth Chambers

Biofilms are surface-attached communities of microorganisms embedded in an extracellular matrix and are essential for the cycling of organic matter in natural and engineered environments.

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