scholarly journals Source characterization of organic carbon using elemental, isotopic and n-alkanes proxies in surface sediment from Lake Bosten, Xinjiang

2015 ◽  
Vol 27 (5) ◽  
pp. 983-990 ◽  
Author(s):  
YU Zhitong ◽  
◽  
WANG Xiujun ◽  
ZHAO Chengyi ◽  
LAN Haiyan
Keyword(s):  
Organic Carbon ◽  
Surface Sediment ◽  
Source Characterization

Source characterization of disinfection byproduct precursors in two Arkansas water-supply reservoirs

Fact Sheet ◽  
1997 ◽  
Author(s):  
Michael L. Pomes ◽  
W.R. Green ◽  
E.M. Thurman ◽  
W.H. Orem ◽  
H.T. Lerch
Keyword(s):  
Water Supply ◽  
Source Characterization ◽  
Disinfection Byproduct ◽  
Water Supply Reservoirs

scholarly journals High resolution characterization of the soil organic carbon depth profile in a soil landscape affected by erosion

2016 ◽  
Vol 156 ◽  
pp. 185-193 ◽  
Author(s):  
Emilien Aldana Jague ◽  
Michael Sommer ◽  
Nicolas P.A. Saby ◽  
Jean-Thomas Cornelis ◽  
Bas Van Wesemael ◽  
...  
Keyword(s):  
High Resolution ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Depth Profile ◽  
Soil Landscape

scholarly journals Quantifying primary and secondary humic-like substances in urban aerosol based on emission source characterization and a source-oriented air quality model

2018 ◽  
Author(s):  
Xinghua Li ◽  
Junzan Han ◽  
Philip K. Hopke ◽  
Jingnan Hu ◽  
Qi Shu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
Coal Combustion ◽  
Power Plants ◽  
Water Soluble ◽  
Aerosol Formation ◽  
Source Characterization ◽  
Air Quality Model ◽  
Coal Burning ◽  
Residential Coal

Abstract. Humic-like substances (HULIS) are a mixture of high molecular weight, water-soluble organic compounds that are widely distributed in atmospheric aerosol. Their sources are rarely studied quantitatively. Biomass burning is generally accepted as a major primary source of ambient humic-like substances (HULIS) with additional secondary material formed in the atmosphere. However, the present study provides direct evidence that residential coal burning is also a significant source of ambient HULIS, especially in the heating season in northern China based on source measurements, ambient sampling and analysis, and apportionment with source-oriented CMAQ modeling. Emissions tests show that residential coal combustion produces 5 to 24 % of the emitted organic carbon (OC) as HULIS carbon (HULISc). Estimation of primary emissions of HULIS in Beijing indicated that residential biofuel and coal burning contribute about 70 % and 25 % of annual primary HULIS, respectively. Vehicle exhaust, industry, and power plants contributions are negligible. Average concentration of ambient HULIS was 7.5 μg/m3 in atmospheric PM2.5 in urban Beijing and HULIS exhibited obvious seasonal variations with the highest concentrations in winter. HULISc account for 7.2 % of PM2.5 mass, 24.5 % of OC, and 59.5 % of water-soluble organic carbon, respectively. HULIS are found to correlate well with K+, Cl−, sulfate, and secondary organic aerosol suggesting its sources include biomass burning, coal combustion and secondary aerosol formation. Source apportionment based on CMAQ modeling shows residential biofuel and coal burning, secondary formation are important annual sources of ambient HULIS, contributing 57.5 %, 12.3 %, and 25.8 %, respectively.

scholarly journals Redefining the Subsurface Biosphere: Characterization of Fungi Isolated From Energy-Limited Marine Deep Subsurface Sediment

2021 ◽  
Vol 2 ◽  
Author(s):  
Brandi Kiel Reese ◽  
Morgan S. Sobol ◽  
Marshall Wayne Bowles ◽  
Kai-Uwe Hinrichs
Keyword(s):  
Organic Carbon ◽  
Growth Parameters ◽  
Carbon Sources ◽  
South Pacific ◽  
Physical Growth ◽  
Energy Budgets ◽  
Deep Subsurface ◽  
Fungal Populations ◽  
South Pacific Gyre

The characterization of metabolically active fungal isolates within the deep marine subsurface will alter current ecosystem models and living biomass estimates that are limited to bacterial and archaeal populations. Although marine fungi have been studied for over fifty years, a detailed description of fungal populations within the deep subsurface is lacking. Fungi possess metabolic pathways capable of utilizing previously considered non-bioavailable energy reserves. Therefore, metabolically active fungi would occupy a unique niche within subsurface ecosystems, with the potential to provide an organic carbon source for heterotrophic prokaryotic populations from the transformation of non-bioavailable energy into substrates, as well as from the fungal necromass itself. These organic carbon sources are not currently being considered in subsurface energy budgets. Sediments from South Pacific Gyre subsurface, one of the most energy-limited environments on Earth, were collected during the Integrated Ocean Drilling Program Expedition 329. Anoxic and oxic sediment slurry enrichments using fresh sediment were used to isolate multiple fungal strains in media types that varied in organic carbon substrates and concentration. Metabolically active and dormant fungal populations were also determined from nucleic acids extracted from in situ cryopreserved South Pacific Gyre sediments. For further characterization of physical growth parameters, two isolates were chosen based on their representation of the whole South Pacific Gyre fungal community. Results from this study show that fungi have adapted to be metabolically active and key community members in South Pacific Gyre sediments and potentially within global biogeochemical cycles.

scholarly journals Integrating macroseismic intensity distributions with a probabilistic approach: an application in Italy

2021 ◽  
Vol 21 (8) ◽  
pp. 2299-2311
Author(s):  
Andrea Antonucci ◽  
Andrea Rovida ◽  
Vera D'Amico ◽  
Dario Albarello
Keyword(s):  
Southern Italy ◽  
Central Italy ◽  
Probabilistic Approach ◽  
Source Characterization ◽  
Strong Earthquakes ◽  
Intensity Prediction ◽  
Macroseismic Intensities ◽  
Earthquake Effects ◽  
Available Information

Abstract. The geographic distribution of earthquake effects quantified in terms of macroseismic intensities, the so-called macroseismic field, provides basic information for several applications including source characterization of pre-instrumental earthquakes and risk analysis. Macroseismic fields of past earthquakes as inferred from historical documentation may present spatial gaps, due to the incompleteness of the available information. We present a probabilistic approach aimed at integrating incomplete intensity distributions by considering the Bayesian combination of estimates provided by intensity prediction equations (IPEs) and data documented at nearby localities, accounting for the relevant uncertainties and the discrete and ordinal nature of intensity values. The performance of the proposed methodology is tested at 28 Italian localities with long and rich seismic histories and for two well-known strong earthquakes (i.e., 1980 southern Italy and 2009 central Italy events). A possible application of the approach is also illustrated relative to a 16th-century earthquake in the northern Apennines.

scholarly journals Molecular characterization of gaseous and particulate oxygenated compounds at a remote site in Cape Corsica in the western Mediterranean Basin

2021 ◽  
Vol 21 (10) ◽  
pp. 8067-8088
Author(s):  
Vincent Michoud ◽  
Elise Hallemans ◽  
Laura Chiappini ◽  
Eva Leoz-Garziandia ◽  
Aurélie Colomb ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carboxylic Acids ◽  
Organic Aerosol ◽  
Western Mediterranean ◽  
Water Soluble ◽  
Molecular Composition ◽  
Particle Phase ◽  
Western Mediterranean Basin ◽  
Partitioning Coefficients

Abstract. The characterization of the molecular composition of organic carbon in both gaseous and aerosol is key to understanding the processes involved in the formation and aging of secondary organic aerosol. Therefore a technique using active sampling on cartridges and filters and derivatization followed by analysis using a thermal desorption–gas chromatography–mass spectrometer (TD–GC–MS) has been used. It is aimed at studying the molecular composition of organic carbon in both gaseous and aerosol phases (PM2.5) during an intensive field campaign which took place in Corsica (France) during the summer of 2013: the ChArMEx (Chemistry and Aerosol Mediterranean Experiment) SOP1b (Special Observation Period 1B) campaign. These measurements led to the identification of 51 oxygenated (carbonyl and or hydroxyl) compounds in the gaseous phase with concentrations between 21 and 3900 ng m−3 and of 85 compounds in the particulate phase with concentrations between 0.3 and 277 ng m−3. Comparisons of these measurements with collocated data using other techniques have been conducted, showing fair agreement in general for most species except for glyoxal in the gas phase and malonic, tartaric, malic and succinic acids in the particle phase, with disagreements that can reach up to a factor of 8 and 20 on average, respectively, for the latter two acids. Comparison between the sum of all compounds identified by TD–GC–MS in the particle phase and the total organic matter (OM) mass reveals that on average 18 % of the total OM mass can be explained by the compounds measured by TD–GC–MS. This number increases to 24 % of the total water-soluble OM (WSOM) measured by coupling the Particle Into Liquid Sampler (PILS)-TOC (total organic carbon) if we consider only the sum of the soluble compounds measured by TD–GC–MS. This highlights the important fraction of the OM mass identified by these measurements but also the relative important fraction of OM mass remaining unidentified during the campaign and therefore the complexity of characterizing exhaustively the organic aerosol (OA) molecular chemical composition. The fraction of OM measured by TD–GC–MS is largely dominated by di-carboxylic acids, which represent 49 % of the PM2.5 content detected and quantified by this technique. Other contributions to PM2.5 composition measured by TD–GC–MS are then represented by tri-carboxylic acids (15 %), alcohols (13 %), aldehydes (10 %), di-hydroxy-carboxylic acids (5 %), monocarboxylic acids and ketones (3 % each), and hydroxyl-carboxylic acids (2 %). These results highlight the importance of polyfunctionalized carboxylic acids for OM, while the chemical processes responsible for their formation in both phases remain uncertain. While not measured by the TD–GC–MS technique, humic-like substances (HULISs) represent the most abundant identified species in the aerosol, contributing for 59 % of the total OM mass on average during the campaign. A total of 14 compounds were detected and quantified in both phases, allowing the calculation of experimental partitioning coefficients for these species. The comparison of these experimental partitioning coefficients with theoretical ones, estimated by three different models, reveals large discrepancies varying from 2 to 7 orders of magnitude. These results suggest that the supposed instantaneous equilibrium being established between gaseous and particulate phases assuming a homogeneous non-viscous particle phase is questionable.

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

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5984 ◽  
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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