Intra‐annual variability of organic carbon concentrations in running waters: Drivers along a climatic gradient

Assays were carried out to evaluate the oxygen consumption resulting from mineralization of different organic compounds: glucose, sucrose, starch, tannic acid, lysine and glycine. The compounds were added to 1 l of water sample from Monjolinho Reservoir. Dissolved oxygen and dissolved organic carbon were monitored during 20 days and the results were fitted to first order kinetics model. During the 20 days of experiments, the oxygen consumption varied from 4.5 mg.l-1 (tannic acid) to 71.5 mg.l-1 (glucose). The highest deoxygenation rate (kD) was observed for mineralization of tannic acid (0.321 day-1) followed by glycine, starch, lysine, sucrose and glucose (0.1004, 0.0504, 0.0486, 0.0251 and 0.0158 day-1, respectively). From theoretical calculations and oxygen and carbon concentrations we obtained the stoichiometry of the mineralization processes. Stoichiometric values varied from 0.17 (tannic acid) to 2.55 (sucrose).

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Predicting soil organic carbon concentrations in a low relief landscape, eastern Iran

Geoderma Regional ◽

10.1016/j.geodrs.2018.e00195 ◽

2018 ◽

Vol 15 ◽

pp. e00195 ◽

Cited By ~ 2

Author(s):

Mohammad Reza Pahlavan-Rad ◽

Khodadad Dahmardeh ◽

Colby Brungard

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Eastern Iran ◽

Carbon Concentrations

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Dissolved organic carbon concentrations and fluxes along the Moisie River, Quebec

Freshwater Biology ◽

10.1111/j.1365-2427.1990.tb00305.x ◽

1990 ◽

Vol 24 (1) ◽

pp. 35-42 ◽

Cited By ~ 14

Author(s):

T. E. FORD ◽

S. A. FORD ◽

M. A. LOCK ◽

R. J. NAIMAN

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Carbon Concentrations

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Concentration and Fluxes of Dissolved Organic Carbon (DOC) in Three Norway Spruce Stands along a Climatic Gradient in Sweden

Biogeochemistry ◽

10.1007/s10533-004-0564-5 ◽

2006 ◽

Vol 77 (1) ◽

pp. 1-23 ◽

Cited By ~ 78

Author(s):

Mats Fröberg ◽

Dan Berggren ◽

Bo Bergkvist ◽

Charlotte Bryant ◽

Jan Mulder

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Norway Spruce ◽

Climatic Gradient ◽

Spruce Stands

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Changes in speciated PM2.5 concentrations in Fresno, California, due to NOx reductions and variations in diurnal emission profiles by day of week

Elem Sci Anth ◽

10.1525/elementa.384 ◽

2019 ◽

Vol 7 ◽

Cited By ~ 2

Author(s):

Benjamin de Foy ◽

James J. Schauer

Keyword(s):

Air Quality ◽

Organic Carbon ◽

Ammonium Nitrate ◽

Forest Fires ◽

Multiple Linear Regression Model ◽

Time Of Day ◽

Multiple Time Scales ◽

Multiple Time ◽

Wood Combustion ◽

Carbon Concentrations

The San Joaquin Valley in California suffers from poor air quality due to a combination of local emissions and weak ventilation. Over the course of decades, there has been a concerted effort to control emissions from vehicles as well as from residential wood burning. A multiple linear regression model was used to evaluate the trends in air pollution over multiple time scales: by year, by season, by day of the week and by time of day. The model was applied to 18 years of measurements in Fresno including hourly mole fractions of NOx and concentrations of PM2.5; and daily measurements of speciated components of PM2.5. The analysis shows that there have been reductions in NOx, elemental carbon and ammonium nitrate of 4 to 6%/year. On weekends, NOx mole fractions are reduced by 15 to 30% due to fewer vehicle miles traveled and a smaller fraction of diesel traffic. These weekend reductions in NOx have not been accompanied by weekend reductions in PM2.5 however. In particular, elemental and organic carbon concentrations are higher on winter weekends. Analysis of diurnal profiles suggests that this is because of increased PM2.5 on Saturday and holiday evenings which are likely due to residential wood combustion. Furthermore, while organic carbon concentrations have decreased in the winter months, they have been variable but without a net decline in the summer, most likely as a result of forest fires offsetting other improvements in air quality. Fog was found to greatly enhance ammonium nitrate formation and was therefore associated with higher PM2.5 in the winter months. Overall the analysis shows that air quality controls have been effective at reducing NOx all year and PM2.5 in the winter, that continued reductions in emissions will further reduce pollutant concentrations, but that winter residential wood combustion and summer forest fires could offset some of the gains obtained.

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Characterization of bacterioplankton communities and quantification of organic carbon pools off the Galapagos Archipelago under contrasting environmental conditions

PeerJ ◽

10.7717/peerj.5984 ◽

2018 ◽

Vol 6 ◽

pp. e5984 ◽

Cited By ~ 4

Author(s):

Nataly Carolina Guevara Campoverde ◽

Christiane Hassenrück ◽

Pier Luigi Buttigieg ◽

Astrid Gärdes

Keyword(s):

Organic Carbon ◽

Carbon Cycle ◽

Dissolved Organic Carbon ◽

Bacterial Communities ◽

Carbon Pools ◽

Aggregate Formation ◽

Galapagos Archipelago ◽

Carbon Concentrations ◽

Bacterioplankton Communities

Bacteria play a crucial role in the marine carbon cycle, contributing to the production and degradation of organic carbon. Here, we investigated organic carbon pools, aggregate formation, and bacterioplankton communities in three contrasting oceanographic settings in the Galapagos Archipelago. We studied a submarine CO2 vent at Roca Redonda (RoR), an upwelling site at Bolivar Channel (BoC) subjected to a weak El Niño event at the time of sampling in October 2014, as well as a site without volcanic or upwelling influence at Cowley Islet (CoI). We recorded physico-chemical parameters, and quantified particulate and dissolved organic carbon, transparent exopolymeric particles, and the potential of the water to form larger marine aggregates. Free-living and particle-attached bacterial communities were assessed via 16S rRNA gene sequencing. Both RoR and BoC exhibited temperatures elevated by 1–1.5 °C compared to CoI. RoR further experienced reduced pH between 6.8 and 7.4. We observed pronounced differences in organic carbon pools at each of the three sites, with highest dissolved organic carbon concentrations at BoC and RoR, and highest particulate organic carbon concentrations and aggregate formation at BoC. Bacterioplankton communities at BoC were dominated by opportunistic copiotrophic taxa, such as Alteromonas and Roseobacter, known to thrive in phytoplankton blooms, as opposed to oligotrophic taxa dominating at CoI, such as members of the SAR11 clade. Therefore, we propose that bacterial communities were mainly influenced by the availability of organic carbon at the investigated sites. Our study provides a comprehensive characterization of organic carbon pools and bacterioplankton communities, highlighting the high heterogeneity of various components of the marine carbon cycle around the Galapagos Archipelago.

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