scholarly journals Warming and ocean acidification may decrease estuarine dissolved organic carbon export to the ocean

2020 ◽  
Author(s):  
Michelle N. Simone ◽  
Kai G. Schulz ◽  
Joanne M. Oakes ◽  
Bradley D. Eyre
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Ocean Acidification ◽  
Heterotrophic Bacteria ◽  
Temperature Response ◽  
Future Climate ◽  
Estuarine Sediments ◽  
Ex Situ ◽  
Large Contribution ◽  
Labile Organic Matter

Abstract. Estuaries make a disproportionately large contribution of dissolved organic carbon (DOC) to the global carbon cycle, but it is unknown how this will change under a future climate. As such, the response of DOC fluxes from microbially dominated unvegetated sediments to individual and combined future climate stressors of warming (from Δ−3 °C to Δ+5 °C on ambient mean temperatures) and ocean acidification (OA, ~2 times the current partial pressure of CO2, pCO2) was investigated ex situ. Warming alone increased sediment heterotrophy, resulting in a proportional increase in sediment DOC uptake, with sediments becoming net sinks of DOC (3.5 to 8.8 mmol-C m−2 d−1) at warmer temperatures (Δ+3 °C and Δ+5 °C, respectively). This temperature response changed under OA conditions, with sediments becoming more autotrophic and a greater sink of DOC (1 to 4 times greater than under current-pCO2). This response was attributed to the stimulation of heterotrophic bacteria with the autochthonous production of labile organic matter by microphytobenthos. Extrapolating these results to the global area of unvegetated subtidal estuarine sediments, the future climate of warming (Δ+3 °C) and OA may decrease the estuarine export of DOC by ~80 % (~150 Tg-C yr−1) and have a disproportionately large impact on the global DOC budget.

scholarly journals Warming and ocean acidification may decrease estuarine dissolved organic carbon export to the ocean

2021 ◽  
Vol 18 (5) ◽  
pp. 1823-1838
Author(s):  
Michelle N. Simone ◽  
Kai G. Schulz ◽  
Joanne M. Oakes ◽  
Bradley D. Eyre
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Ocean Acidification ◽  
Heterotrophic Bacteria ◽  
Future Climate ◽  
Estuarine Sediments ◽  
Ex Situ ◽  
Large Contribution ◽  
Labile Organic Matter ◽  
Co2 Partial Pressure

Abstract. Relative to their surface area, estuaries make a disproportionately large contribution of dissolved organic carbon (DOC) to the global carbon cycle, but it is unknown how this will change under a future climate. As such, the response of DOC fluxes from microbially dominated unvegetated sediments to individual and combined future climate stressors of temperature change (from Δ−3 to Δ+5 ∘C compared to ambient mean temperatures) and ocean acidification (OA, ∼ 2× current CO2 partial pressure, pCO2) was investigated ex situ. Warming alone increased sediment heterotrophy, resulting in a proportional increase in sediment DOC uptake; sediments became net sinks of DOC (3.5 to 8.8 mmol C m−2 d−1) at warmer temperatures (Δ+3 and Δ+5 ∘C, respectively). This temperature response changed under OA conditions, with sediments becoming more autotrophic and a greater sink of DOC (up to 4× greater than under current pCO2 conditions). This response was attributed to the stimulation of heterotrophic bacteria with the autochthonous production of labile organic matter by microphytobenthos. Extrapolating these results to the global area of unvegetated subtidal estuarine sediments, we find that the future climate of warming (Δ+3 ∘C) and OA may decrease estuarine export of DOC by ∼ 80 % (∼ 150 Tg C yr−1) and have a disproportionately large impact on the global DOC budget.

Impact of Cyanobacterial Associate and Heterotrophic Bacteria on Dissolved Organic Carbon and Metal in Moss and Peat Leachate: Application to Permafrost Thaw in Aquatic Environments

2017 ◽  
Vol 23 (5-6) ◽  
pp. 331-358 ◽  
Author(s):  
Liudmila S. Shirokova ◽  
Joachim Labouret ◽  
Melissa Gurge ◽  
Emmanuelle Gérard ◽  
Irina S. Ivanova ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Heterotrophic Bacteria ◽  
Aquatic Environments ◽  
Permafrost Thaw

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

2011 ◽  
Vol 52 (No. 2) ◽  
pp. 55-63 ◽  
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&nbsp;m<sup>3</sup>/ha caused a significant increase of labile organic matter in the 0&ndash;25 and 25&ndash;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.

Bioavailability of dissolved organic carbon and fulvic acid from an Australian floodplain river and billabong

2007 ◽  
Vol 58 (2) ◽  
pp. 222 ◽  
Author(s):  
Suzanne McDonald ◽  
Jennifer M. Pringle ◽  
Paul D. Prenzler ◽  
Andrea G. Bishop ◽  
Kevin Robards
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Fulvic Acid ◽  
Heterotrophic Bacteria ◽  
Fulvic Acids ◽  
Lag Phase ◽  
Floodplain Ecosystems ◽  
Vital Resource ◽  
Number Of Bacteria

Dissolved organic carbon (DOC) is a vital resource for heterotrophic bacteria in aquatic ecosystems. The bioavailability of fulvic acid, which comprises the majority of aquatic DOC, is not well understood. The present study examined the bioavailability of bulk DOC and fulvic acid from two contrasting but inter-related water bodies: the Murrumbidgee River and adjacent Berry Jerry Lagoon. Bacteria utilised fulvic acids; however, bulk DOC was more bioavailable. Bacteria were able to utilise Murrumbidgee River DOC and fulvic acid more readily than Berry Jerry Lagoon DOC and fulvic acid, suggesting that the quality of carbon may be an important factor to consider when evaluating lateral exchange of nutrients between the main channel and floodplain. Chemical characteristics of fulvic acids appeared to explain some of the variation in fulvic acid bioavailability. The higher the molecular weight and complexity of the fulvic acid, the longer it took for bacteria to utilise the substrate (lag phase), but the larger the number of bacteria that grew on the substrate. The present study calls attention to the need for further multidisciplinary studies to address the quality of carbon in riverine-floodplain ecosystems.

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