Benthic organic carbon release stimulates bacterioplankton production in a clear-water subarctic lake

Fishes that live in the Amazonian environment may be exposed to several kinds of waters: "black waters", containing high dissolved organic carbon and acidic pH, "white waters", with ten fold higher Ca2+ concentrations than black waters and neutral pH, and "clear waters", with two fold higher Ca2+ concentrations than black waters and also neutral pH. Therefore, the aim of the present study was to analyze Ca2+ fluxes in the facultative air-breather Hoplosternum littorale (tamoatá) exposed to different Amazonian waters. Fishes were acclimated in well water (similar to clear water) and later placed in individual chambers for Ca2+ fluxes measurements. After 4 h, water from the chambers was replaced by a different type of water. Transfer of tamoatás to ion-poor black or acidic black water resulted in net Ca2+ loss only in the first 2 h of experiment. However, transfer from black or acidic black water to white water led to only net Ca2+ influxes. The results obtained allowed us to conclude that transfer of tamoatás to ion-poor waters (black and acidic black water) led to transient net Ca2+ loss, while the amount of Ca2+ in the ion-rich white water seems adequate to prevent Ca2+ loss after transfer. Therefore, transfer of tamoatás between these Amazonian waters does not seem to result in serious Ca2+ disturbance.

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Modelling the impact of drainage and drain-blocking on dissolved organic carbon release from peatlands

Journal of Hydrology ◽

10.1016/j.jhydrol.2007.02.016 ◽

2007 ◽

Vol 338 (1-2) ◽

pp. 15-27 ◽

Cited By ~ 22

Author(s):

F. Worrall ◽

H.S. Gibson ◽

T.P. Burt

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Carbon Release ◽

The Impact

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Dissolved and Particulate Organic Carbon in Icelandic Proglacial Streams: A First Estimate

Water ◽

10.3390/w11040748 ◽

2019 ◽

Vol 11 (4) ◽

pp. 748 ◽

Cited By ~ 2

Author(s):

Peter Chifflard ◽

Christina Fasching ◽

Martin Reiss ◽

Lukas Ditzel ◽

Kyle S. Boodoo

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Particulate Organic Carbon ◽

Ice Cap ◽

Glacier Terminus ◽

Fluorescence Measurements ◽

Sampling Locations ◽

Carbon Release ◽

Annual Carbon ◽

Spatio Temporal

Here for the first time, we analyze the concentration of dissolved (DOC) and particulate organic carbon (POC), as well as its optical properties (absorbance and fluorescence) from several proglacial streams across Iceland, the location of Europe’s largest non-polar ice cap. We found high spatial variability of DOC concentrations and dissolved organic matter (DOM) composition during peak melt, sampling 13 proglacial streams draining the 5 main Icelandic glaciers. Although glacial-derived organic matter (OM) was dominated by proteinaceous florescence, organic matter composition was variable among glaciers, often exhibiting relatively higher aromatic content and increased humification (based on absorbance and fluorescence measurements) closer to the glacier terminus, modulated by the presence of glacial lakes. Additional sampling locations the in flow path of the river Hvitá revealed that while POC concentrations decreased downstream, DOC concentrations and the autochthonous fraction of OM increased, suggesting the reworking of the organic carbon by microbial communities, with likely implications for downstream ecosystems as glaciers continue to melt. Based on our measured DOC concentrations ranging from 0.11 mg·L−1 to 0.94 mg·L−1, we estimate a potential annual carbon release of 0.008 ± 0.002 Tg·C·yr−1 from Icelandic glaciers. This non-conservative first estimate serves to highlight the potentially significant contribution of Icelandic pro-glacial streams to the global carbon cycle and the need for the quantification and determination of the spatio-temporal variation of DOC and POC fluxes and their respective drivers, particularly in light of increased rates of melting due to recent trends in climatic warming.

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Light Modulates the Physiology of NonphototrophicActinobacteria

Journal of Bacteriology ◽

10.1128/jb.00740-18 ◽

2019 ◽

Vol 201 (10) ◽

Cited By ~ 5

Author(s):

Julia A. Maresca ◽

Jessica L. Keffer ◽

Priscilla P. Hempel ◽

Shawn W. Polson ◽

Olga Shevchenko ◽

...

Keyword(s):

Organic Carbon ◽

Cellular Response ◽

Action Spectrum ◽

Sugar Transport ◽

Growth Effect ◽

Carbon Uptake ◽

Aquatic Environments ◽

Primary Producers ◽

Carbon And Nitrogen ◽

Carbon Release

ABSTRACTLight is a source of energy and an environmental cue that is available in excess in most surface environments. In prokaryotic systems, conversion of light to energy by photoautotrophs and photoheterotrophs is well understood, but the conversion of light to information and the cellular response to that information have been characterized in only a few species. Our goal was to explore the response of freshwaterActinobacteria, which are ubiquitous in illuminated aquatic environments, to light. We found thatActinobacteriawithout functional photosystems grow faster in the light, likely because sugar transport and metabolism are upregulated in the light. Based on the action spectrum of the growth effect and comparisons of the genomes of threeActinobacteriawith this growth rate phenotype, we propose that the photosensor in these strains is a putative CryB-type cryptochrome. The ability to sense light and upregulate carbohydrate transport during the day could allow these cells to coordinate their time of maximum organic carbon uptake with the time of maximum organic carbon release by primary producers.IMPORTANCESunlight provides information about both place and time. In sunlit aquatic environments, primary producers release organic carbon and nitrogen along with other growth factors during the day. The ability ofActinobacteriato coordinate organic carbon uptake and utilization with production of photosynthate enables them to grow more efficiently in the daytime, and it potentially gives them a competitive advantage over heterotrophs that constitutively produce carbohydrate transporters, which is energetically costly, or produce transporters only after detection of the substrate(s), which delays their response. Understanding how light cues the transport of organic carbon and its conversion to biomass is key to understanding biochemical mechanisms within the carbon cycle, the fluxes through it, and the variety of mechanisms by which light enhances growth.

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Reduced carbon cycle resilience across the Palaeocene–Eocene Thermal Maximum

Climate of the Past ◽

10.5194/cp-14-1515-2018 ◽

2018 ◽

Vol 14 (10) ◽

pp. 1515-1527 ◽

Cited By ~ 2

Author(s):

David I. Armstrong McKay ◽

Timothy M. Lenton

Keyword(s):

Organic Carbon ◽

Carbon Cycle ◽

Deep Ocean ◽

Tipping Point ◽

Tipping Points ◽

Carbon Burial ◽

Thermal Maximum ◽

Organic Carbon Burial ◽

Carbon Release ◽

Hyperthermal Events

Abstract. Several past episodes of rapid carbon cycle and climate change are hypothesised to be the result of the Earth system reaching a tipping point beyond which an abrupt transition to a new state occurs. At the Palaeocene–Eocene Thermal Maximum (PETM) at ∼56 Ma and at subsequent hyperthermal events, hypothesised tipping points involve the abrupt transfer of carbon from surface reservoirs to the atmosphere. Theory suggests that tipping points in complex dynamical systems should be preceded by critical slowing down of their dynamics, including increasing temporal autocorrelation and variability. However, reliably detecting these indicators in palaeorecords is challenging, with issues of data quality, false positives, and parameter selection potentially affecting reliability. Here we show that in a sufficiently long, high-resolution palaeorecord there is consistent evidence of destabilisation of the carbon cycle in the ∼1.5 Myr prior to the PETM, elevated carbon cycle and climate instability following both the PETM and Eocene Thermal Maximum 2 (ETM2), and different drivers of carbon cycle dynamics preceding the PETM and ETM2 events. Our results indicate a loss of “resilience” (weakened stabilising negative feedbacks and greater sensitivity to small shocks) in the carbon cycle before the PETM and in the carbon–climate system following it. This pre-PETM carbon cycle destabilisation may reflect gradual forcing by the contemporaneous North Atlantic Volcanic Province eruptions, with volcanism-driven warming potentially weakening the organic carbon burial feedback. Our results are consistent with but cannot prove the existence of a tipping point for abrupt carbon release, e.g. from methane hydrate or terrestrial organic carbon reservoirs, whereas we find no support for a tipping point in deep ocean temperature.

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