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Sample records for active organic carbon

  1. Organic solvent regeneration of granular activated carbon

    NASA Astrophysics Data System (ADS)

    Cross, W. H.; Suidan, M. T.; Roller, M. A.; Kim, B. R.; Gould, J. P.

    1982-09-01

    The use of activated carbon for the treatment of industrial waste-streams was shown to be an effective treatment. The high costs associated with the replacement or thermal regeneration of the carbon have prohibited the economic feasibility of this process. The in situ solvent regeneration of activated carbon by means of organic solvent extraction was suggested as an economically alternative to thermal regeneration. The important aspects of the solvent regeneration process include: the physical and chemical characteristics of the adsorbent, the pore size distribution and energy of adsorption associated with the activated carbon; the degree of solubility of the adsorbate in the organic solvent; the miscibility of the organic solvent in water; and the temperature at which the generation is performed.

  2. [Effects of different fertilizer application on soil active organic carbon].

    PubMed

    Zhang, Rui; Zhang, Gui-Long; Ji, Yan-Yan; Li, Gang; Chang, Hong; Yang, Dian-Lin

    2013-01-01

    The variation characteristics of the content and components of soil active organic carbon under different fertilizer application were investigated in samples of calcareous fluvo-aquic soil from a field experiment growing winter wheat and summer maize in rotation in the North China Plain. The results showed that RF (recommended fertilization), CF (conventional fertilization) and NPK (mineral fertilizer alone) significantly increased the content of soil dissolved organic carbon and easily oxidized organic carbon by 24.92-38.63 mg x kg(-1) and 0.94-0.58 mg x kg(-1) respectively compared to CK (unfertilized control). The soil dissolved organic carbon content under OM (organic manure) increased greater than those under NPK and single fertilization, soil easily oxidized organic carbon content under OM and NPK increased greater than that under single chemical fertilization. OM and NPK showed no significant role in promoting the soil microbial biomass carbon, but combined application of OM and NPK significantly increased the soil microbial biomass carbon content by 36.06% and 20.69%, respectively. Soil easily oxidized organic carbon, dissolved organic carbon and microbial biomass carbon accounted for 8.41% - 14.83%, 0.47% - 0.70% and 0.89% - 1.20% of the total organic carbon (TOC), respectively. According to the results, the fertilizer application significantly increased the proportion of soil dissolved organic carbon and easily oxidized organic carbon, but there was no significant difference in the increasing extent of dissolved organic carbon. The RF and CF increased the proportion of soil easily oxidized organic carbon greater than OM or NPK, and significantly increased the proportion of microbial biomass carbon. OM or RF had no significant effect on the proportion of microbial biomass carbon. Therefore, in the field experiment, appropriate application of organic manure and chemical fertilizers played an important role for the increase of soil active organic carbon

  3. PREDICTING PREFERENTIAL ADSORPTION OF ORGANICS BY ACTIVATED CARBON

    EPA Science Inventory

    Preferential adsorption of organic compounds onto activated carbon from dilute aqueous solutions was studied to develop a comprehensive theoretical basis for predicting adsorption of multicomponent solutes. The research program investigates why some solutes are strong adsorbers, ...

  4. Adsorption of dissolved natural organic matter by modified activated carbons.

    PubMed

    Cheng, Wei; Dastgheib, Seyed A; Karanfil, Tanju

    2005-06-01

    Adsorption of dissolved natural organic matter (DOM) by virgin and modified granular activated carbons (GACs) was studied. DOM samples were obtained from two water treatment plants before (i.e., raw water) and after coagulation/flocculation/sedimentation processes (i.e., treated water). A granular activated carbon (GAC) was modified by high temperature helium or ammonia treatment, or iron impregnation followed by high temperature ammonia treatment. Two activated carbon fibers (ACFs) were also used, with no modification, to examine the effect of carbon porosity on DOM adsorption. Size exclusion chromatography (SEC) and specific ultraviolet absorbance (SUVA(254)) were employed to characterize the DOMs before and after adsorption. Iron-impregnated (HDFe) and ammonia-treated (HDN) activated carbons showed significantly higher DOM uptakes than the virgin GAC. The enhanced DOM uptake by HDFe was due to the presence of iron species on the carbon surface. The higher uptake of HDN was attributed to the enlarged carbon pores and basic surface created during ammonia treatment. The SEC and SUVA(254) results showed no specific selectivity in the removal of different DOM components as a result of carbon modification. The removal of DOM from both raw and treated waters was negligible by ACF10, having 96% of its surface area in pores smaller than 1 nm. Small molecular weight (MW) DOM components were preferentially removed by ACF20H, having 33% of its surface area in 1--3 nm pores. DOM components with MWs larger than 1600, 2000, and 2700 Da of Charleston raw, Charleston-treated, and Spartanburg-treated waters, respectively, were excluded from the pores of ACF20H. In contrast to carbon fibers, DOM components from entire MW range were removed from waters by virgin and modified GACs. PMID:15927230

  5. Effects of organic carbon sequestration strategies on soil enzymatic activities

    NASA Astrophysics Data System (ADS)

    Puglisi, E.; Suciu, N.; Botteri, L.; Ferrari, T.; Coppolecchia, D.; Trevisan, M.; Piccolo, A.

    2009-04-01

    Greenhouse gases emissions can be counterbalanced with proper agronomical strategies aimed at sequestering carbon in soils. These strategies must be tested not only for their ability in reducing carbon dioxide emissions, but also for their impact on soil quality: enzymatic activities are related to main soil ecological quality, and can be used as early and sensitive indicators of alteration events. Three different strategies for soil carbon sequestration were studied: minimum tillage, protection of biodegradable organic fraction by compost amendment and oxidative polimerization of soil organic matter catalyzed by biometic porfirins. All strategies were compared with a traditional agricultural management based on tillage and mineral fertilization. Experiments were carried out in three Italian soils from different pedo-climatic regions located respectively in Piacenza, Turin and Naples and cultivated with maize or wheat. Soil samples were taken for three consecutive years after harvest and analyzed for their content in phosphates, ß-glucosidase, urease and invertase. An alteration index based on these enzymatic activities levels was applied as well. The biomimetic porfirin application didn't cause changes in enzymatic activities compared to the control at any treatment or location. Enzymatic activities were generally higher in the minimum tillage and compost treatment, while differences between location and date of samplings were limited. Application of the soil alteration index based on enzymatic activities showed that soils treated with compost or subjected to minimum tillage generally have a higher biological quality. The work confirms the environmental sustainability of the carbon sequestering agronomical practices studied.

  6. Liquid-phase adsorption of organic compounds by granular activated carbon and activated carbon fibers

    SciTech Connect

    Lin, S.H.; Hsu, F.M.

    1995-06-01

    Liquid-phase adsorption of organic compounds by granular activated carbon (GAC) and activated carbon fibers (ACFs) is investigated. Acetone, isopropyl alcohol (IPA), phenol, and tetrahydrofuran (THF) were employed as the model compounds for the present study. It is observed from the experimental results that adsorption of organic compounds by GAC and ACF is influenced by the BET (Brunauer-Emmett-Teller) surface area of adsorbent and the molecular weight, polarity, and solubility of the adsorbate. The adsorption characteristics of GAC and ACFs were found to differ rather significantly. In terms of the adsorption capacity of organic compounds, the time to reach equilibrium adsorption, and the time for complete desorption, ACFs have been observed to be considerably better than GAC. For the organic compounds tested here, the GAC adsorptions were shown to be represented well by the Langmuir isotherm while the ACF adsorption could be adequately described by the Langmuir or the Freundlich isotherm. Column adsorption tests indicated that the exhausted ACFs can be effectively regenerated by static in situ thermal desorption at 150 C, but the same regeneration conditions do not do as well for the exhausted GAC.

  7. Activation of peroxymonosulfate by graphitic carbon nitride loaded on activated carbon for organic pollutants degradation.

    PubMed

    Wei, Mingyu; Gao, Long; Li, Jun; Fang, Jia; Cai, Wenxuan; Li, Xiaoxia; Xu, Aihua

    2016-10-01

    Graphitic carbon nitride supported on activated carbon (g-C3N4/AC) was prepared through an in situ thermal approach and used as a metal free catalyst for pollutants degradation in the presence of peroxymonosulfate (PMS) without light irradiation. It was found that g-C3N4 was highly dispersed on the surface of AC with the increase of surface area and the exposition of more edges and defects. The much easier oxidation of C species in g-C3N4 to CO was also observed from XPS spectra. Acid Orange 7 (AO7) and other organic pollutants could be completely degraded by the g-C3N4/AC catalyst within 20min with PMS, while g-C3N4+PMS and AC+PMS showed no significant activity for the reaction. The performance of the catalyst was significantly influenced by the amount of g-C3N4 loaded on AC; but was nearly not affected by the initial solution pH and reaction temperature. In addition, the catalysts presented good stability. A nonradical mechanism accompanied by radical generation (HO and SO4(-)) in AO7 oxidation was proposed in the system. The CO groups play a key role in the process; while the exposure of more N-(C)3 group can further increase its electron density and basicity. This study can contribute to the development of green materials for sustainable remediation of aqueous organic pollutants. PMID:27214000

  8. REMOVAL OF ORGANIC POLLUTANTS FROM SUBCRITICAL WATER WITH ACTIVATED CARBON

    SciTech Connect

    Steven B. Hawthorne; Arnaud J. Lagadec

    1999-08-01

    The Energy & Environmental Research Center (EERC) has demonstrated that controlling the temperature (and to a lesser extent, the pressure) of water can dramatically change its ability to extract organics and inorganics from matrices ranging from soils and sediments to waste sludges and coal. The dielectric constant of water can be changed from about 80 (a very polar solvent) to <5 (similar to a nonpolar organic solvent) by controlling the temperature (from ambient to about 400 C) and pressure (from about 5 to 350 bar). The EERC has shown that hazardous organic pollutants such as pesticides, PACS (polycyclic aromatic hydrocarbons), and PCBs (polychlorinated biphenyls) can be completely removed from soils, sludges, and sediments at temperatures (250 C) and pressures (<50 atm) that are much milder than typically used for supercritical water processes (temperature >374 C, pressure >221 atm). In addition, the process has been demonstrated to be particularly effective for samples containing very high levels of contaminants (e.g., part per thousand). Current projects include demonstrating the subcritical water remediation process at the pilot scale using an 8-liter system constructed under separate funding during 1997. To date, subcritical water has been shown to be an effective extraction fluid for removing a variety of organic pollutants from soils and sludges contaminated with fossil fuel products and waste products, including PACS from soil (e.g., town gas sites), refining catalysts, and petroleum tank bottom sludges; PCBs from soil and sediments; toxic gasoline components (e.g., benzene) from soil and waste sludge; and phenols from petroleum refinery sludges. The obvious need to clean the wastewater from subcritical water processes led to preliminary experiments with activated carbon placed in line after the extractor. Initial experiments were performed before and after cooling the extractant water (e.g., with water at 200 C and with water cooled to 25 C

  9. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons

    NASA Astrophysics Data System (ADS)

    Brooks, A. J.; Lim, Hyung-nam; Kilduff, James E.

    2012-07-01

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  10. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons.

    PubMed

    Brooks, A J; Lim, Hyung-nam; Kilduff, James E

    2012-07-27

    Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of π-electron energy to investigate the role of π-π electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects

  11. Metal doped carbon nanoneedles and effect of carbon organization with activity for hydrogen evolution reaction (HER).

    PubMed

    Araujo, Rafael A; Rubira, Adley F; Asefa, Tewodros; Silva, Rafael

    2016-02-10

    Cellulose nanowhiskers (CNW) from cotton, was prepared by acid hydrolysis and purified using a size selection process to obtain homogeneous samples with average particle size of 270 nm and 85.5% crystallinity. Purified CNW was used as precursor to carbon nanoneedles (CNN) synthesis. The synthesis of CNN loaded with different metals dopants were carried out by a nanoreactor method and the obtained CNNs applied as electrocatalysts for hydrogen evolution reaction (HER). In the carbon nanoneedles synthesis, Ni, Cu, or Fe worked as graphitization catalyst and the metal were found present as dopants in the final material. The used metal appeared to have direct influence on the degree of organization of the particles and also in the surface density of polar groups. It was evaluated the influence of the graphitic organization on the general properties and nickel was found as the more appropriate metal since it leads to a more organized material and also to a high activity toward HER. PMID:26686184

  12. Adsorption of organic contaminants by graphene nanosheets, carbon nanotubes and granular activated carbons under natural organic matter preloading conditions.

    PubMed

    Ersan, Gamze; Kaya, Yasemin; Apul, Onur G; Karanfil, Tanju

    2016-09-15

    The effect of NOM preloading on the adsorption of phenanthrene (PNT) and trichloroethylene (TCE) by pristine graphene nanosheets (GNS) and graphene oxide nanosheet (GO) was investigated and compared with those of a single-walled carbon nanotube (SWCNT), a multi-walled carbon nanotube (MWCNT), and two coal based granular activated carbons (GACs). PNT uptake was higher than TCE by all adsorbents on both mass and surface area bases. This was attributed to the hydrophobicity of PNT. The adsorption capacities of PNT and TCE depend on the accessibility of the organic molecules to the inner regions of the adsorbent which was influenced from the molecular size of OCs. The adsorption capacities of all adsorbents decreased as a result of NOM preloading due to site competition and/or pore/interstice blockage. However, among all adsorbents, GO was generally effected least from the NOM preloading for PNT, whereas there was not observed any trend of NOM competition with a specific adsorbent for TCE. In addition, SWCNT was generally affected most from the NOM preloading for TCE and there was not any trend for PNT. The overall results indicated that the fate and transport of organic contaminants by GNSs and CNTs type of nanoadsorbents and GACs in different natural systems will be affected by water quality parameters, characteristics of adsorbent, and properties of adsorbate. PMID:27107611

  13. TAILORING ACTIVATED CARBONS FOR ENHANCED REMOVAL OF NATURAL ORGANIC MATTER FROM NATURAL WATERS. (R828157)

    EPA Science Inventory

    Several pathways have been employed to systematically modify two granular activated carbons (GACs), F400 (coal-based) and Macro (wood-based), for examining adsorption of dissolved natural organic matter (DOM) from natural waters. A total of 24 activated carbons with different ...

  14. PREDICTION OF SELECTIVITY FOR ACTIVATED CARBON ADSORPTION OF TRACE ORGANIC (HOMOLOGUE) CONTAMINANTS

    EPA Science Inventory

    Preferential adsorption of organic compounds onto activated carbon from dilute aqueous solutions was studied to develop a comprehensive theoretical basis for predicting adsorption of multicomponent solutes. The authors investigated in this research program a comparison of differe...

  15. BREAKPOINT CHLORINATION/ACTIVATED CARBON TREATMENT: EFFECT ON VOLATILE HALOGENATED ORGANICS

    EPA Science Inventory

    The production and removal of six volatile halogenated organic compounds during treatment of tertiary clarified and filtered wastewater by breakpoint chlorination and activated carbon was examined in a continuous flow pilot plant. Short contact time breakpoint chlorination of fil...

  16. Cellulase activity and dissolved organic carbon release from lignocellulose macrophyte-derived in four trophic conditions.

    PubMed

    Bottino, Flávia; Cunha-Santino, Marcela Bianchessi; Bianchini, Irineu

    2016-01-01

    Considering the importance of lignocellulose macrophyte-derived for the energy flux in aquatic ecosystems and the nutrient concentrations as a function of force which influences the decomposition process, this study aims to relate the enzymatic activity and lignocellulose hydrolysis in different trophic statuses. Water samples and two macrophyte species were collected from the littoral zone of a subtropical Brazilian Reservoir. A lignocellulosic matrix was obtained using aqueous extraction of dried plant material (≈40°C). Incubations for decomposition of the lignocellulosic matrix were prepared using lignocelluloses, inoculums and filtered water simulating different trophic statuses with the same N:P ratio. The particulate organic carbon and dissolved organic carbon (POC and DOC, respectively) were quantified, the cellulase enzymatic activity was measured by releasing reducing sugars and immobilized carbon was analyzed by filtration. During the cellulose degradation indicated by the cellulase activity, the dissolved organic carbon daily rate and enzyme activity increased. It was related to a fast hydrolysable fraction of cellulose that contributed to short-term carbon immobilization (ca. 10 days). After approximately 20 days, the dissolved organic carbon and enzyme activity were inversely correlated suggesting that the respiration of microorganisms was responsible for carbon mineralization. Cellulose was an important resource in low nutrient conditions (oligotrophic). However, the detritus quality played a major role in the lignocelluloses degradation (i.e., enzyme activity) and carbon release. PMID:26991278

  17. Assessment of bacterial growth and total organic carbon removal on granular activated carbon contactors.

    PubMed Central

    Bancroft, K; Maloney, S W; McElhaney, J; Suffet, I H; Pipes, W O

    1983-01-01

    The overall growth rate of bacteria on granular activated carbon (GAC) contactors at the Philadelphia Torresdale Water Treatment Pilot Plant facility was found to decrease until steady state was reached. The growth rate was found to fluctuate between 6.94 X 10(-3) and 8.68 X 10(-4) doublings per h. The microbiological removal of total organic carbon (TOC) was calculated by considering the GAC contactors as semiclosed continuous culture systems and using growth yield factors determined in laboratory experiments. After ozonation, the average TOC entering the contactors was 1,488 micrograms/liter, and the average effluent TOC was 497 micrograms/liter. Microbiological TOC removal was found to average 240 micrograms/liter on GAC contactors, which was not significantly different from microbiological TOC (220 micrograms/liter) removal across a parallel sand contactor where no adsorption took place. Thus, GAC did not appear to enhance biological TOC removal. Bacterial growth and maintenance was responsible for approximately 24% of the TOC removal on GAC under the conditions of this study. PMID:6639023

  18. Adsorption equilibria of chlorinated organic solvents onto activated carbon

    SciTech Connect

    Yun, J.H.; Choi, D.K.; Kim, S.H.

    1998-04-01

    Adsorption equilibria of dichloromethane, 1,1,1-trichloroethane, and trichloroethylene on activated carbon were obtained by a static volumetric technique. Isotherms were measured for the pure vapors in the temperature range from 283 to 363 K and pressures up to 60 kPa for dichloromethane, 16 kPa for 1,1,1-trichloroethane, and 7 kPa for trichloroethylene, respectively. The Toth and Dubinin-Radushkevich equations were used to correlate experimental isotherms. Thermodynamic properties such as the isosteric heat of adsorption and the henry`s constant were calculated. It was found that the values of isosteric heat of adsorption were varied with surface loading. Also, the Henry`s constant showed that the order of adsorption affinity is 1,1,1-trichloroethane, trichloroethylene, and dichloromethane. By employing the Dubinin-Radushkevich equation, the limiting volume of the adsorbed space, which equals micropore volume, was determined, and its value was found to be approximately independent of adsorbates.

  19. Removal of organic dyes using Cr-containing activated carbon prepared from leather waste.

    PubMed

    Oliveira, Luiz C A; Coura, Camila Van Zanten; Guimarães, Iara R; Gonçalves, Maraisa

    2011-09-15

    In this work, hydrogen peroxide decomposition and oxidation of organics in aqueous medium were studied in the presence of activated carbon prepared from wet blue leather waste. The wet blue leather waste, after controlled pyrolysis under CO(2) flow, was transformed into chromium-containing activated carbons. The carbon with Cr showed high microporous surface area (up to 889 m(2)g(-1)). Moreover, the obtained carbon was impregnated with nanoparticles of chromium oxide from the wet blue leather. The chromium oxide was nanodispersed on the activated carbon, and the particle size increased with the activation time. It is proposed that these chromium species on the carbon can activate H(2)O(2) to generate HO radicals, which can lead to two competitive reactions, i.e. the hydrogen peroxide decomposition or the oxidation of organics in water. In fact, in this work we observed that activated carbon obtained from leather waste presented high removal of methylene blue dye combining the adsorption and oxidation processes. PMID:21752544

  20. Granular activated carbon for removal of organic matter and turbidity from secondary wastewater.

    PubMed

    Hatt, J W; Germain, E; Judd, S J

    2013-01-01

    A range of commercial granular activated carbon (GAC) media have been assessed as pretreatment technologies for a downstream microfiltration (MF) process. Media were assessed on the basis of reduction in both organic matter and turbidity, since these are known to cause fouling in MF membranes. Isotherm adsorption analysis through jar testing with supplementary column trials revealed a wide variation between the different adsorbent materials with regard to organics removal and adsorption kinetics. Comparison with previous work using powdered activated carbon (PAC) revealed that for organic removal above 60% the use of GAC media incurs a significantly lower carbon usage rate than PAC. All GACs tested achieved a minimum of 80% turbidity removal. This combination of turbidity and organic removal suggests that GAC would be expected to provide a significant reduction in fouling of a downstream MF process with improved product water quality. PMID:23306264

  1. Estimating organic micro-pollutant removal potential of activated carbons using UV absorption and carbon characteristics.

    PubMed

    Zietzschmann, Frederik; Altmann, Johannes; Ruhl, Aki Sebastian; Dünnbier, Uwe; Dommisch, Ingvild; Sperlich, Alexander; Meinel, Felix; Jekel, Martin

    2014-06-01

    Eight commercially available powdered activated carbons (PAC) were examined regarding organic micro-pollutant (OMP) removal efficiencies in wastewater treatment plant (WWTP) effluent. PAC characteristic numbers such as B.E.T. surface, iodine number and nitrobenzene number were checked for their potential to predict the OMP removal of the PAC products. Furthermore, the PAC-induced removal of UV254 nm absorption (UVA254) in WWTP effluent was determined and also correlated with OMP removal. None of the PAC characteristic numbers can satisfactorily describe OMP removal and accordingly, these characteristics have little informative value on the reduction of OMP concentrations in WWTP effluent. In contrast, UVA254 removal and OMP removal correlate well for carbamazepine, diclofenac, and several iodinated x-ray contrast media. Also, UVA254 removal can roughly describe the average OMP removal of all measured OMP, and can accordingly predict PAC performance in OMP removal. We therefore suggest UVA254 as a handy indicator for the approximation of OMP removal in practical applications where direct OMP concentration quantification is not always available. In continuous operation of large-scale plants, this approach allows for the efficient adjustment of PAC dosing to UVA254, in order to ensure reliable OMP removal whilst minimizing PAC consumption. PMID:24651017

  2. MULTICOMPONENT ADSORPTION OF VOLATILE ORGANIC CHEMICALS ONTO GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    A technique has been developed to predict the fixed-bed removal of known SOCs in background mixtures of unknown composition. In addition, this technique was used to relate the removal of important SOCs to nonspecific measures of contamination such as total organic halogen (TOX). ...

  3. Modeling high adsorption capacity and kinetics of organic macromolecules on super-powdered activated carbon.

    PubMed

    Matsui, Yoshihiko; Ando, Naoya; Yoshida, Tomoaki; Kurotobi, Ryuji; Matsushita, Taku; Ohno, Koichi

    2011-02-01

    The capacity to adsorb natural organic matter (NOM) and polystyrene sulfonates (PSSs) on small particle-size activated carbon (super-powdered activated carbon, SPAC) is higher than that on larger particle-size activated carbon (powdered-activated carbon, PAC). Increased adsorption capacity is likely attributable to the larger external surface area because the NOM and PSS molecules do not completely penetrate the adsorbent particle; they preferentially adsorb near the outer surface of the particle. In this study, we propose a new isotherm equation, the Shell Adsorption Model (SAM), to explain the higher adsorption capacity on smaller adsorbent particles and to describe quantitatively adsorption isotherms of activated carbons of different particle sizes: PAC and SPAC. The SAM was verified with the experimental data of PSS adsorption kinetics as well as equilibrium. SAM successfully characterized PSS adsorption isotherm data for SPACs and PAC simultaneously with the same model parameters. When SAM was incorporated into an adsorption kinetic model, kinetic decay curves for PSSs adsorbing onto activated carbons of different particle sizes could be simultaneously described with a single kinetics parameter value. On the other hand, when SAM was not incorporated into such an adsorption kinetic model and instead isotherms were described by the Freundlich model, the kinetic decay curves were not well described. The success of the SAM further supports the adsorption mechanism of PSSs preferentially adsorbing near the outer surface of activated carbon particles. PMID:21172719

  4. Tracking small mountainous river derived terrestrial organic carbon across the active margin marine environment

    NASA Astrophysics Data System (ADS)

    Childress, L. B.; Blair, N. E.; Orpin, A. R.

    2015-12-01

    Active margins are particularly efficient in the burial of organic carbon due to the close proximity of highland sources to marine sediment sinks and high sediment transport rates. Compared with passive margins, active margins are dominated by small mountainous river systems, and play a unique role in marine and global carbon cycles. Small mountainous rivers drain only approximately 20% of land, but deliver approximately 40% of the fluvial sediment to the global ocean. Unlike large passive margin systems where riverine organic carbon is efficiently incinerated on continental shelves, small mountainous river dominated systems are highly effective in the burial and preservation of organic carbon due to the rapid and episodic delivery of organic carbon sourced from vegetation, soil, and rock. To investigate the erosion, transport, and burial of organic carbon in active margin small mountainous river systems we use the Waipaoa River, New Zealand. The Waipaoa River, and adjacent marine depositional environment, is a system of interest due to a large sediment yield (6800 tons km-2 yr-1) and extensive characterization. Previous studies have considered the biogeochemistry of the watershed and tracked the transport of terrestrially derived sediment and organics to the continental shelf and slope by biogeochemical proxies including stable carbon isotopes, lignin phenols, n-alkanes, and n-fatty acids. In this work we expand the spatial extent of investigation to include deep sea sediments of the Hikurangi Trough. Located in approximately 3000 m water depth 120 km from the mouth of the Waipaoa River, the Hikurangi Trough is the southern extension of the Tonga-Kermadec-Hikurangi subduction system. Piston core sediments collected by the National Institute of Water and Atmospheric Research (NIWA, NZ) in the Hikurangi Trough indicate the presence of terrestrially derived material (lignin phenols), and suggest a continuum of deposition, resuspension, and transport across the margin

  5. COST ANALYSIS OF ACTIVATED CARBON VERSUS PHOTOCATALYTIC OXIDATION FOR REMOVING ORGANIC COMPOUNDS FROM INDOOR AIR

    EPA Science Inventory

    A cost comparison has been conducted of 1 m3/s indoor air cleaners using granular activated carbon (GAC) vs. photocatalytic oxidation (PCO) for treating a steady-state inlet volatile organic compound (VOC) concentration of 0.3 mg/m3. The commercial GAC unit was costed assuming t...

  6. Selection of desorbing solvents for organic compounds from active carbon tubes.

    PubMed

    Matsumura, Y

    1996-01-01

    To ensure the effective performance of active carbon tubes for working environment measurements, suitable desorbing solvents were selected for 46 kinds of organic compounds by the phase equilibrium method. The criteria for suitable desorbing solvents in this study was desorption of the objective compounds from active carbon at efficiencies greater than 90% and to give good separation between its own peak and that of the objective compound on a gas chromatogram. For most non-polar or hydrophobic compounds, carbon disulfide was a versatile and effective solvent. But for polar and hydrophilic compounds like alcohol, N,N-dimethylformamide and dimethylsulfoxide were good desorbing solvents if their peaks did not overlap with those of the objective compounds. Mixtures of lower molecular weight alcohols with carbon disulfide or dichloromethane could be alternative solvents for hydrophilic compounds as well. A thermodynamic parameter of the solute-solvent system, i.e., the mixing energy derived from the solubility parameter, gave a rough indication of the effectiveness of solvents but it could not be used as a critical indicator for the efficient desorbing solvents for organic vapors collected on active carbon. PMID:8768662

  7. The effects of aging on the dynamic adsorption of hazardous organic vapors on impregnated activated carbon.

    PubMed

    Amitay-Rosen, Tal; Leibman, Amir; Nir, Ido; Zaltsman, Amalia; Kaplan, Doron

    2015-01-01

    The effects of an eight-year natural aging of ASC impregnated activated carbon on the adsorption capacity and breakthrough times of model organic vapors and of the nerve agent sarin were investigated. Aging delayed methanol breakthrough from dry air on pre-dried carbon, but shortened the breakthrough time of both methanol and hexane under relative humidity (RH) of 30-85% on pre-humidified carbon. Aging also shortened the breakthrough time of the less volatile model compound 2-methoxyethanol, especially under RH of 60-85%. Aging significantly reduced the protection capacity against sarin at RH of 85%. The effects of aging on physisorption are attributed to enhanced hydrogen-bonding capability and strength of the interaction between water and adsorption sites on the carbon surface. PMID:25192468

  8. Regulation of bacterial metabolic activity by dissolved organic carbon and viruses

    NASA Astrophysics Data System (ADS)

    Xu, Jie; Jing, Hongmei; Sun, Mingming; Harrison, Paul J.; Liu, Hongbin

    2013-12-01

    regulation of bacterial metabolic activity by viruses and dissolved organic carbon (DOC) was examined using natural microbial communities in three treatments (active viruses, inactive viruses, and virus free) at two contrasting coastal sites (pristine vs. eutrophic) with substantial differences in environmental conditions during the wet and dry seasons. Our results showed that net growth rates and production of bacterioplankton were reduced primarily by viruses via repressing metabolically active bacteria with high nucleic acid (HNA) content which had a high capacity for incorporating carbon, while bacterial respiration was primarily regulated by DOC lability. The quality of organic matter played a more important role in regulating bacterial growth efficiency (BGE) than the supply of organic matter in eutrophic coastal waters. The lack of HMW-DOC and high carbon demand in the virus-free treatment resulted in a significant increase in cell-specific bacterial respiration, which was responsible for the lowest bacterial growth efficiency among the three treatments. The presence of viruses did not necessarily lower bacterial growth efficiency since virus-induced mortality alleviated bacterial carbon demand and enhanced carbon cycling. Virus-induced mortality was greater in relatively pristine waters than eutrophic waters, likely since the high supply of substrates alleviated the pressure of viral infection, through extracellular proteases produced by bacteria, which might result in the hydrolytic destruction or modification of viral capsids. An important implication of our results was that the input of riverine DOC and nutrients improved bacterial metabolic activity by alleviating virus-induced mortality of bacteria in estuarine and coastal waters.

  9. Dynamic adsorption of organic solvent vapors onto a packed bed of activated carbon cloth

    SciTech Connect

    Huang, C.C.; Lin, Y.C.; Lu, F.C.

    1999-02-01

    The adsorption behavior of organic compound vapors onto a packed bed of activated carbon cloth (ACC) has been investigated. Three types of ACCs have been employed: KF1500, FT200-20, and E-ACC. The volatile organic compounds (VOCs) used in this study are acetone, dichloromethane, acrylonitrile, and n-hexane. The operating parameters studied are temperature of adsorber, weight of ACC, relative humidity of fluid, inlet concentration of VOCs, and total volumetric flow rate of gas stream. A simple theoretical model, originally introduced by Yoon and Nelson, has been utilized to simulate the breakthrough curve of VOC vapor on an adsorption column packed with activated carbon cloth. A modified model is proposed to predict the adsorption behavior of an adsorber at different temperatures.

  10. Sorption of DOM and hydrophobic organic compounds onto sewage-based activated carbon.

    PubMed

    Björklund, Karin; Li, Loretta Y

    2016-01-01

    Treatment of stormwater via sorption has the potential to remove both colloidal and dissolved pollutants. Previous research shows that activated carbon produced from sewage sludge is very efficient in sorbing hydrophobic organic compounds (HOCs), frequently detected in stormwater. The aim of this research was to determine whether the presence of dissolved organic matter (DOM) has a negative effect on the adsorption of HOCs onto sludge-based activated carbon (SBAC) in batch adsorption tests. Batch adsorption tests were used to investigate the influence of two types of DOM - soil organic matter and humic acid (HA) technical standard - on the sorption of HOCs onto SBAC, and whether preloading adsorbent and adsorbates with DOM affects HOC sorption. The results indicate that soil DOM and HAs do not have a significant negative effect on the adsorption of HOCs under tested experimental conditions, except for a highly hydrophobic compound. In addition, preloading SBAC or HOCs with DOM did not lead to lower adsorption of HOCs. Batch adsorption tests appear to be inefficient for investigating DOM effects on HOC adsorption, as saturating the carbon is difficult because of high SBAC adsorption capacity and low HOC solubility, so that limited competition occurs on the sorbent. PMID:27533860

  11. Impacts of ozonation on the competition between organic micro-pollutants and effluent organic matter in powdered activated carbon adsorption.

    PubMed

    Zietzschmann, F; Mitchell, R-L; Jekel, M

    2015-11-01

    This study investigates if ozonation of wastewater treatment plant (WWTP) effluent can reduce the negative impacts of effluent organic matter (EfOM) on the adsorption of organic micro-pollutants (OMP) onto powdered activated carbon (PAC). Pre-treatment of the water included membrane filtration for the removal of suspended/colloidal organics, ozonation with various specific ozone consumptions, and subsequent OMP spiking to comparable initial concentrations in all of the ozonated waters. This approach allowed for comparative PAC adsorption tests. Adsorption analyses show that the adsorbability of EfOM decreases with increasing specific ozone consumptions. This is also reflected by liquid chromatography with online carbon and UV254 detection (LC-OCD) which shows the ozone-induced disintegration of large EfOM into smaller fragments. Also, small organic neutrals are decreased while the small organic acids peak continuously increases with rising specific ozone consumptions. UV254 demonstrates that the aromaticity of all LC-OCD fractions continuously declines together with increasing specific O3 consumptions. This explains the varying EfOM adsorbabilities that occur due to ozonation. The ozone-induced decrease of EfOM adsorbability directly translates into reduced adsorption competition against the adsorption of OMP. With higher specific ozone consumptions, OMP removal and OMP loadings increase. The reduced adsorption competition is reflected in the outputs from equivalent background compound (EBC) modeling. In each of the ozonated waters, correlations between the OMP removals and the UV254 removal were found. PMID:26231581

  12. Reuse of spent granular activated carbon for organic micro-pollutant removal from treated wastewater.

    PubMed

    Hu, Jingyi; Shang, Ran; Heijman, Bas; Rietveld, Luuk

    2015-09-01

    Spent granular activated carbons (sGACs) for drinking water treatments were reused via pulverizing as low-cost adsorbents for micro-pollutant adsorption from a secondary treated wastewater effluent. The changes of physicochemical characteristics of the spent carbons in relation to the fresh carbons were determined and were correlated to the molecular properties of the respective GAC influents (i.e. a surface water and a groundwater). Pore size distribution analysis showed that the carbon pore volume decreased over a wider size range due to preloading by surface water, which contains a broader molecular weight distribution of organic matter in contrast to the groundwater. However, there was still considerable capacity available on the pulverized sGACs for atrazine adsorption in demineralized water and secondary effluent, and this was particularly the case for the groundwater spent GAC. However, as compared to the fresh counterparts, the decreased surface area and the induced surface acidic groups on the pulverized sGACs contributed both to the lower uptake and the more impeded adsorption kinetic of atrazine in the demineralized water. Nonetheless, the pulverized sGACs, especially the one preloaded by surface water, was less susceptible to adsorption competition in the secondary effluent, due to its negatively charged surface which can repulse the accessibility of the co-present organic matter. This suggests the reusability of the drinking water spent GACs for micro-pollutant adsorption in the treated wastewater. PMID:26093103

  13. Biodegradation of persistent organics can overcome adsorption-desorption hysteresis in biological activated carbon systems.

    PubMed

    Abromaitis, V; Racys, V; van der Marel, P; Meulepas, R J W

    2016-04-01

    In Biological Activated Carbon (BAC) systems, persistent organic pollutants can be removed through a combination of adsorption, desorption and biodegradation. These processes might be affected by the presence of other organics, especially by the more abundant easily-biodegradable organics, like acetate. In this research these relations are quantified for the removal of the persistent pharmaceutical metoprolol. Acetate did not affect the adsorption and desorption of metoprolol, but it did greatly enhance the metoprolol biodegradation. At least part of the BAC biomass growing on acetate was also able to metabolise metoprolol, although metoprolol was only converted after the acetate was depleted. The presence of easily-degradable organics like acetate in the feeding water is therefore beneficial for the removal of metoprolol in BAC systems. The isotherms obtained from metoprolol adsorption and desorption experiments showed that BAC systems are subject to hysteresis; for AC bioregeneration to take place the microbial biomass has to reduce the concentration at the AC-biomass interface 2.7 times compared to the concentration at which the carbon was being loaded. However, given the threshold concentration of the MET degrading microorganisms (<0.08 μg/L) versus the average influent concentration (1.3 μg/L), bioregeneration is feasible. PMID:26855223

  14. [Effects of biological regulated measures on active organic carbon and erosion-resistance in the Three Gorges Reservoir region soil].

    PubMed

    Huang, Ru; Huang, Lin; He, Bing-Hui; Zhou, Li-Jiang; Yu, Chuan; Wang, Feng

    2013-07-01

    To gain a better knowledge of characteristics of soils and provide a scientific basis for soil erosion control in the Three Gorges Reservoir Area, contents of aggregates and total soil organic carbon (SOC), as well as soil active organic carbon fractions including particulate organic carbon (POC), readily oxidized organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) in the 0-30 cm soil layer under seven different biological regulated measures were studied by the field investigation combined with the laboratory analysis. Results showed that the content of the SOC and active organic carbon fractions decreased with the increasing soil depth; the content of the SOC and active organic carbon fractions in 0-10 cm was significantly higher than that in 20-30 cm. The stability of soil aggregates were also significantly influenced by biological regulated measures, the content of > 0.25 mm water-stable aggregates in seven types of biological regulated measures was in the order of Koelreuteria bipinnata + Cassia suffruticasa > hedgerows > closed forest > natural restoration > economic forest > traditional planting > control plot, moreover, the content of 0.25 mm water-stable aggregates correlated positively with the content of SOC. Soils under different biological regulated measures all demonstrated fractal features, and soil under the measure of Koelreuteria bipinnata + Cassia suffruticasa was found to have the lowest value of fractal dimension and soil erodiable K, indicating a relatively strong structure stability and erosion-resistant capacity. Negative correlation was observed when compared the content of active organic carbon fractions with the soil erodiable K. It can be concluded that properties of soil can be managed through biological regulated measures; thence had an influence on the soil erosion-resistant capacity. PMID:24028016

  15. Potential impact of microbial activity on the oxidant capacity and organic carbon budget in clouds.

    PubMed

    Vaïtilingom, Mickael; Deguillaume, Laurent; Vinatier, Virginie; Sancelme, Martine; Amato, Pierre; Chaumerliac, Nadine; Delort, Anne-Marie

    2013-01-01

    Within cloud water, microorganisms are metabolically active and, thus, are expected to contribute to the atmospheric chemistry. This article investigates the interactions between microorganisms and the reactive oxygenated species that are present in cloud water because these chemical compounds drive the oxidant capacity of the cloud system. Real cloud water samples with contrasting features (marine, continental, and urban) were taken from the puy de Dôme mountain (France). The samples exhibited a high microbial biodiversity and complex chemical composition. The media were incubated in the dark and subjected to UV radiation in specifically designed photo-bioreactors. The concentrations of H(2)O(2), organic compounds, and the ATP/ADP ratio were monitored during the incubation period. The microorganisms remained metabolically active in the presence of ()OH radicals that were photo-produced from H(2)O(2). This oxidant and major carbon compounds (formaldehyde and carboxylic acids) were biodegraded by the endogenous microflora. This work suggests that microorganisms could play a double role in atmospheric chemistry; first, they could directly metabolize organic carbon species, and second, they could reduce the available source of radicals through their oxidative metabolism. Consequently, molecules such as H(2)O(2) would no longer be available for photochemical or other chemical reactions, which would decrease the cloud oxidant capacity. PMID:23263871

  16. Potential impact of microbial activity on the oxidant capacity and organic carbon budget in clouds

    NASA Astrophysics Data System (ADS)

    Vaïtilingom, Mickael; Deguillaume, Laurent; Vinatier, Virginie; Sancelme, Martine; Amato, Pierre; Chaumerliac, Nadine; Delort, Anne-Marie

    2013-01-01

    Within cloud water, microorganisms are metabolically active and, thus, are expected to contribute to the atmospheric chemistry. This article investigates the interactions between microorganisms and the reactive oxygenated species that are present in cloud water because these chemical compounds drive the oxidant capacity of the cloud system. Real cloud water samples with contrasting features (marine, continental, and urban) were taken from the puy de Dôme mountain (France). The samples exhibited a high microbial biodiversity and complex chemical composition. The media were incubated in the dark and subjected to UV radiation in specifically designed photo-bioreactors. The concentrations of H2O2, organic compounds, and the ATP/ADP ratio were monitored during the incubation period. The microorganisms remained metabolically active in the presence of ●OH radicals that were photo-produced from H2O2. This oxidant and major carbon compounds (formaldehyde and carboxylic acids) were biodegraded by the endogenous microflora. This work suggests that microorganisms could play a double role in atmospheric chemistry; first, they could directly metabolize organic carbon species, and second, they could reduce the available source of radicals through their oxidative metabolism. Consequently, molecules such as H2O2 would no longer be available for photochemical or other chemical reactions, which would decrease the cloud oxidant capacity.

  17. Preparation of Nano-Porous Activated Carbon Aerogel Using a Single-Step Activation Method for Use as High-Power EDLC Electrode in Organic Electrolyte.

    PubMed

    Kwon, Soon Hyung; Kim, Bum-Soo; Kim, Sang-Gil; Lee, Byung-Jun; Kim, Myung-Soo; Jung, Ji Chul

    2016-05-01

    Carbon aerogel was chemically activated with KOH using two different activation methods (conventional activation method and single-step activation method) to yield the nano-porous activated carbon aerogel. Both nano-porous activated carbon aerogels exhibited a better capacitive behavior than carbon aerogel in organic electrolyte. However, a drastic decrease in the specific capacitance with increasing current density was observed in the ACA_C (activated carbon aerogel prepared by a conventional activation method), which is a general tendency of carbon electrode for EDLC in organic electrolyte. Interestingly, the specific capacitance of ACA_S electrode (activated carbon aerogel prepared by a single-step activation method) decreased slowly with increasing current density and its CV curve maintained a rectangular shape well even at a high scan rate of 500 mV/s. The enhanced electrochemical performance of ACA_S at a high current density was attributed to its low ionic resistance caused by the well-developed pore structure with appropriate pore size for easy moving of organic electrolyte ion. Therefore, it can be concluded that single-step activation method could be one of the efficient methods for preparation of nano-porous activated carbon aerogel electrode for high-power EDLC in organic electrolyte. PMID:27483797

  18. Understanding the fate of organic micropollutants in sand and granular activated carbon biofiltration systems.

    PubMed

    Paredes, L; Fernandez-Fontaina, E; Lema, J M; Omil, F; Carballa, M

    2016-05-01

    In this study, sand and granular activated carbon (GAC) biofilters were comparatively assessed as post-treatment technologies of secondary effluents, including the fate of 18 organic micropollutants (OMPs). To determine the contribution of adsorption and biotransformation in OMP removal, four reactors were operated (two biofilters (with biological activity) and two filters (without biological activity)). In addition, the influence of empty bed contact time (EBCT), ranging from 0.012 to 3.2d, and type of secondary effluent (anaerobic and aerobic) were evaluated. Organic matter, ammonium and nitrate were removed in both biofilters, being their adsorption higher on GAC than on sand. According to the behaviour exhibited, OMPs were classified in three different categories: I) biotransformation and high adsorption on GAC and sand (galaxolide, tonalide, celestolide and triclosan), II) biotransformation, high adsorption on GAC but low or null adsorption on sand (ibuprofen, naproxen, fluoxetine, erythromycin, roxythromycim, sulfamethoxazole, trimethoprim, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol), and, III) only adsorption on GAC (carbamazepine, diazepam and diclofenac). No influence of EBCT (in the range tested) and type of secondary effluent was observed in GAC reactors, whereas saturation and kinetic limitation of biotransformation were observed in sand reactors. Taking into account that most of the organic micropollutants studied (around 60%) fell into category II, biotransformation is crucial for the elimination of OMPs in sand biofilters. PMID:26897407

  19. Active Marine Subsurface Bacterial Population Composition in Low Organic Carbon Environments from IODP Expedition 320

    NASA Astrophysics Data System (ADS)

    Shepard, A.; Reese, B. K.; Mills, H. J.; IODP Expedition 320 Shipboard Science Party

    2011-12-01

    The marine subsurface environment contains abundant and active microorganisms. These microbial populations are considered integral players in the marine subsurface biogeochemical system with significance in global geochemical cycles and reservoirs. However, variations in microbial community structure, activity and function associated with the wide-ranging sedimentary and geochemical environments found globally have not been fully resolved. Integrated Ocean Drilling Program Expedition 320 recovered sediments from site U1332. Two sampling depths were selected for analysis that spanned differing lithological units in the sediment core. Sediments were composed of mostly clay with zeolite minerals at 8 meters below sea floor (mbsf). At 27 mbsf, sediments were composed of alternating clayey radiolarian ooze and nannofossil ooze. The concentration of SO42- had little variability throughout the core and the concentration of Fe2+ remained close to, or below, detection limits (0.4 μM). Total organic carbon content ranged from a low of 0.03 wt% to a high of 0.07 wt% between 6 and 30 mbsf providing an opportunity to evaluate marine subsurface microbial communities under extreme electron donor limiting conditions. The metabolically active fraction of the bacterial population was isolated by the extraction and amplification of 16S ribosomal RNA. Pyrosequencing of 16S rRNA transcripts and subsequent bioinformatic analyses provided a robust data set (15,931 total classified sequences) to characterize the community at a high resolution. As observed in other subsurface environments, the overall diversity of active bacterial populations decreased with depth. The population shifted from a diverse but evenly distributed community at approximately 8 mbsf to a Firmicutes dominated population at 27 mbsf (80% of sequences). A total of 95% of the sequences at 27 mbsf were grouped into three genera: Lactobacillus (phylum Firmicutes) at 80% of the total sequences, Marinobacter (phylum

  20. [Nitrous oxide emission during denitrification for activated sludge acclimated with methanol as the organic carbon].

    PubMed

    Zhai, Xiao-Feng; Jiang, Cheng-Ai; Wu, Guang-Xue; Guan, Yun-Tao

    2013-04-01

    Denitrification of wastewater is one of the important sources of nitrous oxide (N2O). In this study, denitrifies were acclimated in a sequencing batch reactor with methanol and nitrate (NO3(-) -N) as the electron donor and acceptor, respectively. N2O emission during denitrification was examined both in typical cycles and in batch experiments under conditions of different electron acceptors, carbon/nitrogen (C/N) ratios and initial nitrite (NO2(-)-N) concentrations. With methanol as the organic carbon, the N2O emission was high with NO2(-)-N as the electron acceptor and the N2O emission was low with NO3(-) -N as the electron acceptor. The C/N ratios affected the emission of N2O by affecting activities of denitrifiers, and both the activity of denitrifiers and the emission of N2O decreased with decreasing C/N ratios. The N2O emission increased with increasing initial NO2(-) -N concentrations, and a certain range of NO2(-) -N concentrations enhanced the activity of denitrifiers. The N2O emission could be correlated very well with initial NO2(-) -N concentrations. PMID:23798124

  1. Emissions of carbon species, organic polar compounds, potassium, and mercury from prescribed burning activities

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Obrist, D.; Zielinska, B.; Gerler, A.

    2012-04-01

    Biomass burning is an important emission source of pollutants to the atmosphere, but few studies have focused on the chemical composition of emissions from prescribed burning activities. Here we present results from a sampling campaign to quantify particulate-phase emissions from various types of prescribed fires including carbon species (Elemental Carbon: EC; Organic Carbon: OC; and Total Carbon: TC); polar organic compounds (12 different compounds and four functional classes); water-soluble potassium (K+); and mercury (Hg). We measured emissions from the following types of prescribed biomass burning in the Lake Tahoe basin located on the California/Nevada border: (i) log piles stacked and dried in the field; (ii) log piles along with green understory vegetation; and (iii) understory green vegetation and surface litter; further emissions were collected from burns conducted in a wood stove: (iv) dried wooden logs; (v) green foliage of understory vegetation collected from the field; and (vi) surface organic litter collected from the field; finally, samples were also taken from (vii) ambient air in residential areas during peak domestic wood combustion season. Results show that OC/EC ratios of prescribed burns in the field ranged from 4 to 10, but lower values (around 1) were observed in controlled stove fires. These results are consistent with an excess of OC emissions over EC found in wildfires. OC/EC ratios, however, showed clear separations between controlled wood stove combustion (higher EC) and prescribed burns in the field (lower EC). We attribute this difference to a higher combustion temperatures and dominance of flaming combustion in wood stove fires. OC positively and linearly correlated to the sum of polar organic compounds across all burn types (r2 of 0.82). The most prevalent group of polar compounds emitted during prescribed fires was resin acids (dehydroabietic, pimaric, and abietic acids), followed by levoglucosan plus mannositol. Negligible

  2. Removal of organic contaminants from aqueous solution by cattle manure compost (CMC) derived activated carbons

    NASA Astrophysics Data System (ADS)

    Qian, Qingrong; Chen, Qinghua; Machida, Motoi; Tatsumoto, Hideki; Mochidzuki, Kazuhiro; Sakoda, Akiyoshi

    2009-04-01

    The activated carbons (ACs) prepared from cattle manure compost (CMC) with various pore structure and surface chemistry were used to remove phenol and methylene blue (MB) from aqueous solutions. The adsorption equilibrium and kinetics of two organic contaminants onto the ACs were investigated and the schematic models for the adsorptive processes were proposed. The result shows that the removal of functional groups from ACs surface leads to decreasing both rate constants for phenol and MB adsorption. It also causes the decrement of MB adsorption capacity. However, the decrease of surface functional groups was found to result in the increase of phenol adsorption capacity. In our schematic model for adsorptive processes, the presence of acidic functional groups on the surface of carbon is assumed to act as channels for diffusion of adsorbate molecules onto small pores, therefore, promotes the adsorption rate of both phenol and MB. In phenol solution, water molecules firstly adsorb on surface oxygen groups by H-bonding and subsequently form water clusters, which cause partial blockage of the micropores, deduce electrons from the π-electron system of the carbon basal planes, hence, impede or prevent phenol adsorption. On the contrary, in MB solution, the oxygen groups prefer to combine with MB + cations than water molecules, which lead to the increase of MB adsorption capacity.

  3. Wastewater treatment--adsorption of organic micropollutants on activated HTC-carbon derived from sewage sludge.

    PubMed

    Kirschhöfer, Frank; Sahin, Olga; Becker, Gero C; Meffert, Florian; Nusser, Michael; Anderer, Gilbert; Kusche, Stepan; Klaeusli, Thomas; Kruse, Andrea; Brenner-Weiss, Gerald

    2016-01-01

    Organic micropollutants (MPs), in particular xenobiotics and their transformation products, have been detected in the aquatic environment and the main sources of these MPs are wastewater treatment plants. Therefore, an additional cleaning step is necessary. The use of activated carbon (AC) is one approach to providing this additional cleaning. Industrial AC derived from different carbonaceous materials is predominantly produced in low-income countries by polluting processes. In contrast, AC derived from sewage sludge by hydrothermal carbonization (HTC) is a regional and sustainable alternative, based on waste material. Our experiments demonstrate that the HTC-AC from sewage sludge was able to remove most of the applied MPs. In fact more than 50% of sulfamethoxazole, diclofenac and bezafibrate were removed from artificial water samples. With the same approach carbamazepine was eliminated to nearly 70% and atrazine more than 80%. In addition a pre-treated (phosphorus-reduced) HTC-AC was able to eliminate 80% of carbamazepine and diclofenac. Atrazine, sulfamethoxazole and bezafibrate were removed to more than 90%. Experiments using real wastewater samples with high organic content (11.1 g m(-3)) succeeded in proving the adsorption capability of phosphorus-reduced HTC-AC. PMID:26877044

  4. Biofiltration of a mixture of volatile organic compounds on granular activated carbon.

    PubMed

    Aizpuru, A; Malhautier, L; Roux, J C; Fanlo, J L

    2003-08-20

    The performance of a biofilter packed with Active Carbon (AC) was evaluated. The effluent (alcohol, ketones, esters, aromatic and chlorinated compounds) treated was a representative mixture of most common industrial emissions. To achieve a better knowledge of multicomponent adsorption mechanisms, and to underline the interest of inoculating AC, a control abiotic humidified filter had been operated in the same conditions as the biofilter. For a load of 110 g VOC m(-3) AC h(-1), after 55 days of operation, the removal efficiency was higher in the biotic than in the abiotic filter (85% vs 55%, respectively). Moreover, in the biofilter, at steady state, the elimination of all compounds was almost complete except for chlorinated compounds and p-xylene (removal efficiency of 25% and 64%, respectively). The microbial colonization of AC involved a decrease of the adsorption sites accessibility and enhanced the treatment of VOCs (volatile organic compounds) having a lower affinity for activated carbon. Moreover, while aromatic compounds and MIBK were eliminated along the overall height of the biofilter, pollutants with reduced affinity for AC, such as methanol, acetone, and halogenated compounds were only treated on the second half of the reactor. Thus, the affinity for activated carbon was an important parameter controlling the biodegradation process. Nevertheless, the use of AC as packing material in biofilters treating complex mixtures of VOCs is limited. Actually, similar removal efficiency could be reached, in the same conditions, for a biofilter packed with granular peat. Furthermore, for the biofilter packed with AC, the column height necessary to remove biodegradable compounds, with reduced affinity for the support, was important. PMID:12800142

  5. Adsorption of clofibric acid and ketoprofen onto powdered activated carbon: effect of natural organic matter.

    PubMed

    Gao, Yaohuan; Deshusses, Marc A

    2011-12-01

    The adsorption of two acidic pharmaceutically active compounds (PhACs), clofibric acid and ketoprofen, onto powdered activated carbon (PAC) was investigated with a particular focus on the influence of natural organic matter (NOM) on the adsorption of the PhACs. Suwannee River humic acids (SRHAs) were used as a substitute for NOM. Batch adsorption experiments were conducted to obtain adsorption kinetics and adsorption isotherms with and without SRHAs in the system. The adsorption isotherms and adsorption kinetics showed that the adsorption ofclofibric acid was not significantly affected by the presence of SRHAs at a concentration of 5 mg (as carbon) L(-1). An adsorption capacity of 70 to 140 mg g(-1) was observed and equilibrium was reached within 48 h. In contrast, the adsorption of ketoprofen was markedly decreased (from about 120 mg g(-1) to 70-100 mg g(-1)) in the presence of SRHAs. Higher initial concentrations of clofibric acid than ketoprofen during testing may explain the different behaviours that were observed. Also, the more hydrophobic ketoprofen molecules may have less affinity for PAC when humic acids (which are hydrophilic) are present. The possible intermolecular forces that could account for the different behaviour of clofibric acid and ketoprofen adsorption onto PAC are discussed. In particular, the relevance of electrostatic forces, electron donor-acceptor interaction, hydrogen bonding and London dispersion forces are discussed PMID:22439557

  6. A model to predict the adsorber thermal behavior during treatment of volatile organic compounds onto wet activated carbon.

    PubMed

    Pré, P; Delage, F; Le Cloirec, P

    2002-11-01

    A model for adsorption of volatile organic compounds (VOCs) onto a wet activated carbon bed was proposed in this study. This model accounts for temperature changes induced by the reversed and coupled mass-transfer processes of both organic species adsorption and water desorption. Indeed, it was experimentally pointed out that temperature rises, which result from the exothermal nature of the energetic interactions between the organic molecule and the activated carbon surface, are notably reduced when the adsorbent contains an initial moisture of approximately 10% in weight. Moreover, it was shown that water rate desorption was enhanced in the presence of organic vapor. This phenomenon may be explained by the displacement of sorbed water bythe organic molecules, owing to more intensive interactions with the activated carbon surface. The model proposed was elaborated from a previous comprehensive analysis of the diffusion mechanisms governing VOC adsorption at high concentrations onto a dry activated carbon bed. In a similar way, a theoretical approach was developed to model water desorption during drying of a wet activated carbon bed under pure flowing air. At last, a theoretical depiction of both competitive and reverse processes was outlined. The final model fits reasonably with experimental data relative to both breakthrough curves and thermal wave shape along the bed, even if local temperature change calculation may require some further improvement. PMID:12433182

  7. Predicting trace organic compound breakthrough in granular activated carbon using fluorescence and UV absorbance as surrogates.

    PubMed

    Anumol, Tarun; Sgroi, Massimiliano; Park, Minkyu; Roccaro, Paolo; Snyder, Shane A

    2015-06-01

    This study investigated the applicability of bulk organic parameters like dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), and total fluorescence (TF) to act as surrogates in predicting trace organic compound (TOrC) removal by granular activated carbon in water reuse applications. Using rapid small-scale column testing, empirical linear correlations for thirteen TOrCs were determined with DOC, UV254, and TF in four wastewater effluents. Linear correlations (R(2) > 0.7) were obtained for eight TOrCs in each water quality in the UV254 model, while ten TOrCs had R(2) > 0.7 in the TF model. Conversely, DOC was shown to be a poor surrogate for TOrC breakthrough prediction. When the data from all four water qualities was combined, good linear correlations were still obtained with TF having higher R(2) than UV254 especially for TOrCs with log Dow>1. Excellent linear relationship (R(2) > 0.9) between log Dow and the removal of TOrC at 0% surrogate removal (y-intercept) were obtained for the five neutral TOrCs tested in this study. Positively charged TOrCs had enhanced removals due to electrostatic interactions with negatively charged GAC that caused them to deviate from removals that would be expected with their log Dow. Application of the empirical linear correlation models to full-scale samples provided good results for six of seven TOrCs (except meprobamate) tested when comparing predicted TOrC removal by UV254 and TF with actual removals for GAC in all the five samples tested. Surrogate predictions using UV254 and TF provide valuable tools for rapid or on-line monitoring of GAC performance and can result in cost savings by extended GAC run times as compared to using DOC breakthrough to trigger regeneration or replacement. PMID:25792436

  8. Separation of hydrophobic organic compound from surfactant solutions with activated carbon in a fixed bed.

    PubMed

    Liu, Jianfei; Chen, Jiajun; Jiang, Lin; Chen, Cheng

    2013-01-01

    The adsorption behavior of phenanthrene (PHE) in Triton X-100 (TX100) solutions with fixed activated carbon (AC) bed was studied to recover the surfactant. The effect of various parameters like bed depths, flow rates, influent TX100 concentration, and influent PHE concentration were investigated. The breakthrough time of both TX100 and PHE increased with the increase of bed height and decrease of flow rate and influent concentration. In the case of fixed length, a lower flow rate, higher concentration of TX100, and lower concentration of PHE will benefit the longer effective surfactant recovery time. The adsorption data were integrated into bed depth service time models. The height of exchange zone of TX100 should be much shorter than that of PHE, which provides conditions to separate the hydrophobic organic compound from surfactant solutions with AC in a fixed bed. It is likely that the adsorption process is controlled by hydrophobic interaction. PMID:24292481

  9. Effect of biochar or activated carbon amendment on the volatilisation and biodegradation of organic soil pollutants

    NASA Astrophysics Data System (ADS)

    Werner, David; Meynet, Paola; Bushnaf, Khaled

    2013-04-01

    Biochar or activated carbon added to contaminated soil may temporarily reduce the volatilisation of organic pollutants by enhanced sorption. The long-term effect of sorbent amendments on the fate of volatile petroleum hydrocarbon mixtures (VPHs) will depend on the responses of the soil bacterial community members, especially those which may utilize VPHs as carbon substrates. We investigated the volatilisation and biodegradation of VPHs emanating from NAPL sources and migrating through one meter long columns containing unsaturated sandy soil with and without 2% biochar or activated carbon amendment. After 420 days, VPH volatilisation from AC amended soil was less than 10 percent of the cumulative VPH volatilisation flux from unamended soil. The cumulative CO2 volatilisation flux increased more slowly in AC amended soil, but was comparable to the untreated soil after 420 days. This indicated that the pollution attenuation over a 1 meter distance was improved by the AC amendment. Biochar was a weaker VPH sorbent than AC and had a lesser effect on the cumulative VPH and CO2 fluxes. We also investgated the predominant bacterial community responses in sandy soil to biochar and/or VPH addition with a factorially designed batch study, and by analyzing preserved soil samples. Biochar addition alone had only weak effects on soil bacterial communities, while VPH addition was a strong community structure shaping factor. The bacterial community effects of biochar-enhanced VPH sorption were moderated by the limited biomass carrying capacity of the sandy soil investigated which contained only low amounts of inorganic nitrogen. Several Pseudomonas spp., including Pseudomonas putida strains, became dominant in VPH polluted soil with and without biochar. The ability of these versatile VPH degraders to effectively regulate their metabolic pathways according to substrate availabilities may additionally have moderated bacterial community structure responses to the presence of biochar

  10. Extraction of organic materials from red water by metal-impregnated lignite activated carbon.

    PubMed

    Wei, Fangfang; Zhang, Yihe; Lv, Fengzhu; Chu, Paul K; Ye, Zhengfang

    2011-12-15

    Extraction of organic materials from 2,4,6-trinitrotoluene (TNT) red water by lignite activated carbon (LAC) impregnated with Cu(2+), Ba(2+), Sn(2+), Fe(3+), Ca(2+) and Ag(+) was investigated. The affinity to organic materials in red water was found to follow the order: Cu/LAC>Sn/LAC>Ag/LAC>Ba/LAC>Fe/LAC>Ca/LAC, which was explained by the hard and soft acid base (HSAB) theory. Cu(2+) showed the best performance and several parameters were further studied. X-ray photoelectron spectroscopy (XPS) verified effective loading of Cu(2+) on the LAC surface. The water quality before and after treated by Cu/LAC was evaluated using high performance liquid chromatograph, Gas Chromatography/Mass Spectroscopy (GC/MS), UV-vis spectroscopy and other analyses. The extraction performances and mechanism of organic materials on Cu/LAC were investigated through static methods. The experimental results showed that Cu/LAC possessed stronger extraction ability for the sulfonated nitrotoluenes than the non-sulfonated nitrotoluenes, the kinetic data fitted the pseudo-second-order kinetic model well. In addition, the leaching out of Cu(2+) from Cu/LAC was found much lower in the 100 times diluted red water (0.074%) than in the raw water (10.201%). Column adsorptions with more concentrated red water were also studied. Finally, Cu/LAC was observed to possess excellent reusability as well. PMID:22015039

  11. Electrochemically active, crystalline, mesoporous covalent organic frameworks on carbon nanotubes for synergistic lithium-ion battery energy storage

    NASA Astrophysics Data System (ADS)

    Xu, Fei; Jin, Shangbin; Zhong, Hui; Wu, Dingcai; Yang, Xiaoqing; Chen, Xiong; Wei, Hao; Fu, Ruowen; Jiang, Donglin

    2015-02-01

    Organic batteries free of toxic metal species could lead to a new generation of consumer energy storage devices that are safe and environmentally benign. However, the conventional organic electrodes remain problematic because of their structural instability, slow ion-diffusion dynamics, and poor electrical conductivity. Here, we report on the development of a redox-active, crystalline, mesoporous covalent organic framework (COF) on carbon nanotubes for use as electrodes; the electrode stability is enhanced by the covalent network, the ion transport is facilitated by the open meso-channels, and the electron conductivity is boosted by the carbon nanotube wires. These effects work synergistically for the storage of energy and provide lithium-ion batteries with high efficiency, robust cycle stability, and high rate capability. Our results suggest that redox-active COFs on conducting carbons could serve as a unique platform for energy storage and may facilitate the design of new organic electrodes for high-performance and environmentally benign battery devices.

  12. Separated Carbon Nanotube Macroelectronics for Active Matrix Organic Light-Emitting Diode Displays

    NASA Astrophysics Data System (ADS)

    Fu, Yue; Zhang, Jialu; Wang, Chuan; Chen, Pochiang; Zhou, Chongwu

    2012-02-01

    Active matrix organic light-emitting diode (AMOLED) display holds great potential for the next generation visual technologies due to its high light efficiency, flexibility, lightweight, and low-temperature processing. However, suitable thin-film transistors (TFTs) are required to realize the advantages of AMOLED. Pre-separated, semiconducting enriched carbon nanotubes are excellent candidates for this purpose because of their excellent mobility, high percentage of semiconducting nanotubes, and room-temperature processing compatibility. Here we report, for the first time, the demonstration of AMOLED displays driven by separated nanotube thin-film transistors (SN-TFTs) including key technology components such as large-scale high-yield fabrication of devices with superior performance, carbon nanotube film density optimization, bilayer gate dielectric for improved substrate adhesion to the deposited nanotube film, and the demonstration of monolithically integrated AMOLED display elements with 500 pixels driven by 1000 SN-TFTs. Our approach can serve as the critical foundation for future nanotube-based thin-film display electronics.

  13. Separated carbon nanotube macroelectronics for active matrix organic light-emitting diode displays.

    PubMed

    Zhang, Jialu; Fu, Yue; Wang, Chuan; Chen, Po-Chiang; Liu, Zhiwei; Wei, Wei; Wu, Chao; Thompson, Mark E; Zhou, Chongwu

    2011-11-01

    Active matrix organic light-emitting diode (AMOLED) display holds great potential for the next generation visual technologies due to its high light efficiency, flexibility, lightweight, and low-temperature processing. However, suitable thin-film transistors (TFTs) are required to realize the advantages of AMOLED. Preseparated, semiconducting enriched carbon nanotubes are excellent candidates for this purpose because of their excellent mobility, high percentage of semiconducting nanotubes, and room-temperature processing compatibility. Here we report, for the first time, the demonstration of AMOLED displays driven by separated nanotube thin-film transistors (SN-TFTs) including key technology components, such as large-scale high-yield fabrication of devices with superior performance, carbon nanotube film density optimization, bilayer gate dielectric for improved substrate adhesion to the deposited nanotube film, and the demonstration of monolithically integrated AMOLED display elements with 500 pixels driven by 1000 SN-TFTs. Our approach can serve as the critical foundation for future nanotube-based thin-film display electronics. PMID:21942351

  14. Preparation and Properties of Metal Organic Framework/Activated Carbon Composite Materials.

    PubMed

    Fleker, Ohad; Borenstein, Arie; Lavi, Ronit; Benisvy, Laurent; Ruthstein, Sharon; Aurbach, Doron

    2016-05-17

    Metal organic frameworks (MOFs) have unique properties that make them excellent candidates for many high-tech applications. Nevertheless, their nonconducting character is an obstacle to their practical utilization in electronic and energy systems. Using the familiar HKUST-1 MOF as a model, we present a new method of imparting electrical conductivity to otherwise nonconducting MOFs by preparing MOF nanoparticles within the conducting matrix of mesoporous activated carbon (AC). This composite material was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), gas adsorption measurements, and electron paramagnetic resonance (EPR) spectroscopy. We show that MOF nanoparticles grown within the carbon matrix maintain their crystalline characteristics and their surface area. Surprisingly, as a result of the composition process, EPR measurements revealed a copper signal that had not yet been achieved. For the first time, we could analyze the complex EPR response of HKUST-1. We demonstrate the high conductivity of the MOF composite and discuss various factors that are responsible for these results. Finally, we present an optional application for using the conductive MOF composite as a high-performance electrode for pseudocapacitors. PMID:27104367

  15. Adsorption and desorption of mixtures of organic vapors on beaded activated carbon.

    PubMed

    Wang, Haiyan; Jahandar Lashaki, Masoud; Fayaz, Mohammadreza; Hashisho, Zaher; Philips, John H; Anderson, James E; Nichols, Mark

    2012-08-01

    In this study, adsorption and desorption of mixtures of organic compounds commonly emitted from automotive painting operations were experimentally studied. A mixture of two alkanes and a mixture of eight organic compounds were adsorbed onto beaded activated carbon (BAC) and then thermally desorbed under nitrogen. Following both adsorption and regeneration, samples of the BAC were chemically extracted. Gas chromatography-mass spectrometry (GC-MS) was used to quantify the compounds in the adsorption and desorption gas streams and in the BAC extracts. In general, for both adsorbate mixtures, competitive adsorption resulted in displacing low boiling point compounds by high boiling point compounds during adsorption. In addition to boiling point, adsorbate structure and functionality affected adsorption dynamics. High boiling point compounds such as n-decane and 2,2-dimethylpropylbenzene were not completely desorbed after three hours regeneration at 288 °C indicating that these two compounds contributed to heel accumulation on the BAC. Additional compounds not present in the mixtures were detected in the extract of regenerated BAC possibly due to decomposition or other reactions during regeneration. Closure analysis based on breakthrough curves, solvent extraction of BAC and mass balance on the reactor provided consistent results of the amount of adsorbates on the BAC after adsorption and/or regeneration. PMID:22742925

  16. The role of beaded activated carbon's surface oxygen groups on irreversible adsorption of organic vapors.

    PubMed

    Jahandar Lashaki, Masoud; Atkinson, John D; Hashisho, Zaher; Phillips, John H; Anderson, James E; Nichols, Mark

    2016-11-01

    The objective of this study is to determine the contribution of surface oxygen groups to irreversible adsorption (aka heel formation) during cyclic adsorption/regeneration of organic vapors commonly found in industrial systems, including vehicle-painting operations. For this purpose, three chemically modified activated carbon samples, including two oxygen-deficient (hydrogen-treated and heat-treated) and one oxygen-rich sample (nitric acid-treated) were prepared. The samples were tested for 5 adsorption/regeneration cycles using a mixture of nine organic compounds. For the different samples, mass balance cumulative heel was 14 and 20% higher for oxygen functionalized and hydrogen-treated samples, respectively, relative to heat-treated sample. Thermal analysis results showed heel formation due to physisorption for the oxygen-deficient samples, and weakened physisorption combined with chemisorption for the oxygen-rich sample. Chemisorption was attributed to consumption of surface oxygen groups by adsorbed species, resulting in formation of high boiling point oxidation byproducts or bonding between the adsorbates and the surface groups. Pore size distributions indicated that different pore sizes contributed to heel formation - narrow micropores (<7Å) in the oxygen-deficient samples and midsize micropores (7-12Å) in the oxygen-rich sample. The results from this study help explain the heel formation mechanism and how it relates to chemically tailored adsorbent materials. PMID:27295065

  17. Predicting trace organic compound attenuation with spectroscopic parameters in powdered activated carbon processes.

    PubMed

    Ziska, Austin D; Park, Minkyu; Anumol, Tarun; Snyder, Shane A

    2016-08-01

    The removal of trace organic compounds (TOrCs) is of growing interest in water research and society. Powdered activated carbon (PAC) has been proven to be an effective method of removal for TOrCs in water, with the degree of effectiveness depending on dosage, contact time, and activated carbon type. In this study, the attenuation of TOrCs in three different secondary wastewater effluents using four PAC materials was studied in order to elucidate the effectiveness and efficacy of PAC for TOrC removal. With the notable exception of hydrochlorothiazide, all 14 TOrC indicators tested in this study exhibited a positive correlation of removal rate with their log Dow values, demonstrating that the main adsorption mechanism was hydrophobic interaction. As a predictive model, the modified Chick-Watson model, often used for the prediction of microorganism inactivation by disinfectants, was applied. The applied model exhibited good predictive power for TOrC attenuation by PAC in wastewater. In addition, surrogate models based upon spectroscopic measurements including UV absorbance at 254 nm and total fluorescence were applied to predict TOrC removal by PAC. The surrogate model was found to provide an excellent prediction of TOrC attenuation for all combinations of water quality and PAC type included in this study. The success of spectrometric parameters as surrogates in predicting TOrC attenuation by PAC are particularly useful because of their potential application in real-time on-line sensor monitoring and process control at full-scale water treatment plants, which could lead to significantly reduced operator response times and PAC operational optimization. PMID:27174829

  18. LSER model for organic compounds adsorption by single-walled carbon nanotubes: Comparison with multi-walled carbon nanotubes and activated carbon.

    PubMed

    Yu, Xiangquan; Sun, Weiling; Ni, Jinren

    2015-11-01

    LSER models for organic compounds adsorption by single and multi-walled carbon nanotubes and activated carbon were successfully developed. The cavity formation and dispersion interactions (vV), hydrogen bond acidity interactions (bB) and π-/n-electron interactions (eE) are the most influential adsorption mechanisms. SWCNTs is more polarizable, less polar, more hydrophobic, and has weaker hydrogen bond accepting and donating abilities than MWCNTs and AC. Compared with SWCNTs and MWCNTs, AC has much less hydrophobic and less hydrophilic adsorption sites. The regression coefficients (e, s, a, b, v) vary in different ways with increasing chemical saturation. Nonspecific interactions (represented by eE and vV) have great positive contribution to organic compounds adsorption, and follow the order of SWCNTs > MWCNTs > AC, while hydrogen bond interactions (represented by aA and bB) demonstrate negative contribution. These models will be valuable for understanding adsorption mechanisms, comparing adsorbent characteristics, and selecting the proper adsorbents for certain organic compounds. PMID:26319510

  19. Selection of pecan shell-based activated carbons for removal of organic and inorganic impurities from water.

    PubMed

    Niandou, Mohamed A S; Novak, Jeffrey M; Bansode, Rishipal R; Yu, Jianmei; Rehrah, Djaafar; Ahmedna, Mohamed

    2013-01-01

    Activated carbons are a byproduct from pyrolysis and have value as a purifying agent. The effectiveness of activated carbons is dependent on feedstock selection and pyrolysis conditions that modify their surface properties. Therefore, pecan shell-based activated carbons (PSACs) were prepared by soaking shells in 50% (v/v) HPO or 25 to 50% of KOH-NaHCO followed by pyrolysis at 400 to 700°C under a N atmosphere. Physically activated PSACs were produced by pyrolysis at 700°C under N followed by activation with steam or CO at 700 to 900°C. Physicochemical, surface, and adsorption properties of the PSACs were compared with two commercially available activated carbons. The average mass yield of PSACs with respect to the initial mass of the biomass was about 20 and 34% for physically activated and chemically activated carbons, respectively. Acid-activated carbons exhibited higher surface area, higher bulk density, and lower ash content compared with steam- or CO-activated carbons and the two commercial products. Base activation led to the development of biochar with moderate to high surface area with surface charges suitable for adsorption of anionic species. Regardless of the activation method, PSACs had high total surface area ranging from 400 to 1000 m g, better pore size distribution, and more surface charges than commercial samples. Our results also showed that PSACs were effective in removing inorganic contaminants such as Cu and NO as well as organic contaminants such as atrazine and metolachlor. This study showed that pyrolysis conditions and activation had a large influence on the PSAC's surface characteristics, which can limit its effectiveness as a custom sorbent for targeted water contaminants. PMID:23673958

  20. Click chemistry from organic halides, diazonium salts and anilines in water catalysed by copper nanoparticles on activated carbon.

    PubMed

    Alonso, Francisco; Moglie, Yanina; Radivoy, Gabriel; Yus, Miguel

    2011-09-21

    An easy-to-prepare, reusable and versatile catalyst consisting of oxidised copper nanoparticles on activated carbon has been fully characterised and found to effectively promote the multicomponent synthesis of 1,2,3-triazoles from organic halides, diazonium salts, and aromatic amines in water at a low copper loading. PMID:21789331

  1. Rates of dissolved organic carbon (DOC) production and bacterial activity in the eastern North Atlantic Subtropical Gyre during summer

    NASA Astrophysics Data System (ADS)

    Teira, E.; Pazó, M. J.; Quevedo, M.; Fuentes, M. V.; Niell, F. X.; Fernández, E.

    2003-04-01

    Rates of particulate organic carbon production, dissolved organic carbon production (DOC) and bacterial production were measured at 8 stations located in the eastern North Atlantic Subtropical Gyre during August 1998. Euphotic-depth-integrated particulate organic carbon (POC) production rate was on average 27 mg C m-2 h-1. The corresponding averaged integrated DOC production rate was 5 mg C m-2 h-1, i.e., about 20 % of total primary production. No statistically significant relationship was found between the rates of DOC and POC production, suggesting that other processes besides phytoplankton exudation, such as cell lysis or protist grazing, could substantially contribute to the release of DOC. Euphotic-depth-integrated bacterial biomass and production were, on average, 214 mg C m-2 and 1.4 mg C m-2 h-1, respectively. The lack of correlation between the rates of DOC release and bacterial activity, and a bacterial carbon demand (BCD, calculated by using an estimated bacterial growth efficiency ranging from 11 to 18%) in excess of DOC production suggest the existence of additional organic carbon sources (both allochthonous and/or autochthonous reservoirs), apart from in situ phytoplankton-derived DOC production, for the maintenance of bacterial activity in this region during summer.

  2. Response of oxidative enzyme activities to nitrogen deposition affects soil concentrations of dissolved organic carbon

    USGS Publications Warehouse

    Waldrop, M.P.; Zak, D.R.

    2006-01-01

    Recent evidence suggests that atmospheric nitrate (NO3- ) deposition can alter soil carbon (C) storage by directly affecting the activity of lignin-degrading soil fungi. In a laboratory experiment, we studied the direct influence of increasing soil NO 3- concentration on microbial C cycling in three different ecosystems: black oak-white oak (BOWO), sugar maple-red oak (SMRO), and sugar maple-basswood (SMBW). These ecosystems span a broad range of litter biochemistry and recalcitrance; the BOWO ecosystem contains the highest litter lignin content, SMRO had intermediate lignin content, and SMBW leaf litter has the lowest lignin content. We hypothesized that increasing soil solution NO 3- would reduce lignolytic activity in the BOWO ecosystem, due to a high abundance of white-rot fungi and lignin-rich leaf litter. Due to the low lignin content of litter in the SMBW, we further reasoned that the NO3- repression of lignolytic activity would be less dramatic due to a lower relative abundance of white-rot basidiomycetes; the response in the SMRO ecosystem should be intermediate. We increased soil solution NO3- concentrations in a 73-day laboratory incubation and measured microbial respiration and soil solution dissolved organic carbon (DOC) and phenolics concentrations. At the end of the incubation, we measured the activity of ??-glucosidase, N-acetyl-glucosaminidase, phenol oxidase, and peroxidase, which are extracellular enzymes involved with cellulose and lignin degradation. We quantified the fungal biomass, and we also used fungal ribosomal intergenic spacer analysis (RISA) to gain insight into fungal community composition. In the BOWO ecosystem, increasing NO 3- significantly decreased oxidative enzyme activities (-30% to -54%) and increased DOC (+32% upper limit) and phenolic (+77% upper limit) concentrations. In the SMRO ecosystem, we observed a significant decrease in phenol oxidase activity (-73% lower limit) and an increase in soluble phenolic concentrations

  3. Effect of effluent organic matter on the adsorption of perfluorinated compounds onto activated carbon.

    PubMed

    Yu, Jing; Lv, Lu; Lan, Pei; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming

    2012-07-30

    Effect of effluent organic matter (EfOM) on the adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) onto powdered activated carbon (PAC) was quantitatively investigated at environmentally relevant concentration levels. The adsorption of both perfluorinated compounds (PFCs) onto PAC followed pseudo-second order kinetics and fitted the Freundlich model well under the given conditions. Intraparticle diffusion was found to be the rate-controlling step in the PFC adsorption process onto PAC in the absence and presence of EfOM. The presence of EfOM, either in PFC-EfOM simultaneous adsorption onto fresh PAC or in PFC adsorption onto EfOM-preloaded PAC, significantly reduced the adsorption capacities and sorption rates of PFCs. The pH of zero point of charge was found to be 7.5 for fresh PAC and 4.2 for EfOM-preloaded PAC, suggesting that the adsorbed EfOM imparted a negative charge on PAC surface. The effect of molecular weight distribution of EfOM on the adsorption of PFCs was investigated with two EfOM fractions obtained by ultrafiltration. The low-molecular-weight compounds (<1kDa) were found to be the major contributors to the significant reduction in PFC adsorption capacity, while large-molecular-weight compounds (>30kDa) had much less effect on PFC adsorption capacity. PMID:22609392

  4. Electrothermal adsorption and desorption of volatile organic compounds on activated carbon fiber cloth.

    PubMed

    Son, H K; Sivakumar, S; Rood, M J; Kim, B J

    2016-01-15

    Adsorption is an effective means to selectively remove volatile organic compounds (VOCs) from industrial gas streams and is particularly of use for gas streams that exhibit highly variable daily concentrations of VOCs. Adsorption of such gas streams by activated carbon fiber cloths (ACFCs) and subsequent controlled desorption can provide gas streams of well-defined concentration that can then be more efficiently treated by biofiltration than streams exhibiting large variability in concentration. In this study, we passed VOC-containing gas through an ACFC vessel for adsorption and then desorption in a concentration-controlled manner via electrothermal heating. Set-point concentrations (40-900 ppm(v)) and superficial gas velocity (6.3-9.9 m/s) were controlled by a data acquisition and control system. The results of the average VOC desorption, desorption factor and VOC in-and-out ratio were calculated and compared for various gas set-point concentrations and superficial gas velocities. Our results reveal that desorption is strongly dependent on the set-point concentration and that the VOC desorption rate can be successfully equalized and controlled via an electrothermal adsorption system. PMID:26342148

  5. Biochar and activated carbon for enhanced trace organic contaminant retention in stormwater infiltration systems.

    PubMed

    Ulrich, Bridget A; Im, Eugenia A; Werner, David; Higgins, Christopher P

    2015-05-19

    To assess the effectiveness of biochar and activated carbon (AC) for enhanced trace organic contaminant (TOrC) retention in stormwater infiltration systems, an approach combining forward-prediction modeling and laboratory verification experiments was employed. Batch and column tests were conducted using representative TOrCs and synthetic stormwater. Based on batch screening tests, two commercially available biochars (BN-biochar and MCG-biochar) and an AC were investigated. The AC exhibited the strongest sorption, followed by MCG-biochar and BN-biochar. Langmuir isotherms provided better fits to equilibrium data than Freundlich isotherms. Due to superior sorption kinetics, 0.2 wt % MCG-biochar in saturated sand columns retained TOrCs more effectively than 1.0 wt % BN-biochar. A forward-prediction intraparticle diffusion model based on the Langmuir isotherm adequately predicted column results when calibrated using only batch parameters, as indicated by a Monte Carlo uncertainty analysis. Case study simulations estimated that an infiltration basin amended with F300-AC or MCG-biochar could obtain sorption-retarded breakthrough times for atrazine of 54 or 5.8 years, respectively, at a 1 in./h infiltration rate. These results indicate that biochars or ACs with superior sorption capacity and kinetics can enhance TOrC retention in infiltration systems, and performance under various conditions can be predicted using results from batch tests. PMID:25909951

  6. Removal of organic and inorganic sulfur compounds by ozone and granular activated carbon

    SciTech Connect

    Shepherd, B.; Ball, G.W.

    1996-11-01

    Most groundwater supplies in the western U.S. are relatively low in dissolved organic matter, are generally free of bacteria, and are platable to their consumers. In areas of western Nevada, certain groundwaters are near active geothermal areas, which can produce sulfurous types of tastes and odors (T&Os) in the water. Other water quality characteristics can consist of either relatively low or highly mineralized waters, variations in pH, and temperatures ranging from those slightly above normal groundwaters to pressurized steam. Watersource Consulting Engineers (WCE) and Shepherd Laboratories (SL) conducted an engineering study of a high-capacity well for a local northwestern Nevada utility. WCE`s original task had been to design pumping and storage facilities for the well, in addition to evaluating basic treatment. Originally, WCE anticipated designing facilities to remove hydrogen sulfide (H{sub 2}S) and reduce color, primarily with chlorination and aeration. SL was requested to evaluate existing water quality and eventually conduct bench-scale testing of several treatment processes. As the study proceeded, the original goals were modified when it became evident that water quality conditions required more extensive evaluation. The study was done in several stages, reflecting the information gained during each stage. The final recommended design criteria included treatment for improving water quality relative to T&O, color, total organic carbon (TOC), and, to a limited extent, fluoride. The water quality goals adopted by the utility encompassed primary maximum contaminant levels (MCLs) for regulatory compliance and secondary MCLs for aesthetically pleasing water. The treatment processes evaluated and recommended in this study were designed primarily to improve the aesthetic qualities of color, taste, and odor. Fluoride reduction was evaluated but was not included in the final design requirements, except for the overall reduction provided by the recommended process.

  7. The removal of organic pollutants by ultrafiltration and adsorption onto fibrous activated carbon

    SciTech Connect

    Le Cloirec, P.; Brasquet, C.; Subrenat, E.

    1996-10-01

    The adsorption of micropollutants in aqueous solutions showed a high adsorption velocity of fiber activated carbon (FAC) compared to granular activated carbon (GAC), and was similar to that of powder activated carbon (PAC). A selectivity of FAC was also found. From these results an ultrafiltration (LTF) membrane is coupled with FAC to remove successively macromolecules (humic substances) and phenols present together in an aqueous solution. This new and original approach to a water treatment compact process is successfully put to use. The influence of operating parameters such as water velocities, between 0.6 and 2.07 m. h{sup -1} and FAC thickness in the range 4 to 16 mm is investigated. Industrial developments are put forward.

  8. Charcoal produced by prescribed fire increases dissolved organic carbon and soil microbial activity

    NASA Astrophysics Data System (ADS)

    Poon, Cheryl; Jenkins, Meaghan; Bell, Tina; Adams, Mark

    2014-05-01

    soil with differing moisture content (55 and 70% water holding capacity). Microbial respiration was measured continuously and dissolved organic C (DOC), nitrogen (DON), extractable phosphorus (P), and microbial C, N and P were measured at four time points during the 72 h incubation. Our data showed that the initial spike in microbial respiration was highly correlated to the amount of DOC in the soil. Soil moisture did not significantly change the microbial response or soil nutrient availability after addition of charcoal. This study outlines one of the processes of carbon cycling that occurs immediately after fire. Charcoal deposition resulting from prescribed burning provides a transitory yet important source of C for soil microbes and stimulates microbial activity.

  9. Impact of Nanoparticles and Natural Organic Matter on the Removal of Organic Pollutants by Activated Carbon Adsorption

    EPA Science Inventory

    Isotherm experiments evaluating trichloroethylene (TCE) adsorption onto powdered activated carbon (PAC) were conducted in the presence and absence of three commercially available nanomaterials— iron oxide (Fe2O3), titanium dioxide (TiO2), and silicon dioxide (SiO2). Isotherm exp...

  10. Comparison between sequential and simultaneous application of activated carbon with membrane bioreactor for trace organic contaminant removal.

    PubMed

    Nguyen, Luong N; Hai, Faisal I; Kang, Jinguo; Nghiem, Long D; Price, William E; Guo, Wenshan; Ngo, Huu H; Tung, Kuo-Lun

    2013-02-01

    The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR-GAC) and simultaneous application of PAC within MBR (PAC-MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50-70%, in MBR-GAC and PAC-MBR, respectively). Based on a simple comparison from the long-term performance stability and activated carbon usage points of view, PAC-MBR appears to be a better option than MBR-GAC treatment. PMID:23313687

  11. PREDICTING THE ADSORPTION CAPACITY OF ACTIVATED CARBON FOR ORGANIC CONTAMINANTS FROM ADSORBENT AND ADSORBATE PROPERTIES

    EPA Science Inventory

    A quantitative structure-property relationship (QSPR) was developed and combined with the Polanyi-Dubinin-Manes model to predict adsorption isotherms of emerging contaminants on activated carbons with a wide range of physico-chemical properties. Affinity coefficients (βl

  12. Effects of surface-active organic matter on carbon dioxide nucleation in atmospheric wet aerosols: a molecular dynamics study.

    PubMed

    Daskalakis, Vangelis; Charalambous, Fevronia; Panagiotou, Fostira; Nearchou, Irene

    2014-11-21

    Organic matter (OM) uptake in cloud droplets produces water-soluble secondary organic aerosols (SOA) via aqueous chemistry. These play a significant role in aerosol properties. We report the effects of OM uptake in wet aerosols, in terms of the dissolved-to-gas carbon dioxide nucleation using molecular dynamics (MD) simulations. Carbon dioxide has been implicated in the natural rainwater as well as seawater acidity. Variability of the cloud and raindrop pH is assumed in space and time, as regional emissions, local human activities and geophysical characteristics differ. Rain scavenging of inorganic SOx, NOx and NH3 plays a major role in rain acidity in terms of acid-base activity, however carbon dioxide solubility also remains a key parameter. Based on the MD simulations we propose that the presence of surface-active OM promotes the dissolved-to-gas carbon dioxide nucleation in wet aerosols, even at low temperatures, strongly decreasing carbon dioxide solubility. A discussion is made on the role of OM in controlling the pH of a cloud or raindrop, as a consequence, without involving OM ionization equilibrium. The results are compared with experimental and computational studies in the literature. PMID:25272147

  13. Low Power, Red, Green and Blue Carbon Nanotube Enabled Vertical Organic Light Emitting Transistors for Active Matrix OLED Displays

    SciTech Connect

    McCarthy, M. A.; Liu, B.; Donoghue, E. P.; Kravchenko, Ivan I; Kim, D. Y.; So, Franky; Rinzler, A. G.

    2011-01-01

    Organic semiconductors are potential alternatives to polycrystalline silicon as the semiconductor used in the backplane of active matrix organic light emitting diode displays. Demonstrated here is a light-emitting transistor with an organic channel, operating with low power dissipation at low voltage, and high aperture ratio, in three colors: red, green and blue. The single-wall carbon nanotube network source electrode is responsible for the high level of performance demonstrated. A major benefit enabled by this architecture is the integration of the drive transistor, storage capacitor and light emitter into a single device. Performance comparable to commercialized polycrystalline-silicon TFT driven OLEDs is demonstrated.

  14. Column studies for the adsorption of cationic surfactant onto an organic polymer resin and a granular activated carbon.

    PubMed

    Vergili, Ilda; Kaya, Yasemin; Gönder, Zeren Beril; Barlas, Hulusi

    2010-03-01

    Adsorption beds containing granular activated carbon and organic polymer resin are used widely to remove organic pollutants from wastewaters and water streams. Adsorption polymers are becoming alternatives to activated carbon for removal of surfactants by adsorption techniques. This study investigated the adsorption characteristics of cetyl trimethylammonium bromide (CTAB) as a cationic surfactant for selected concentrations below and above critical micelle concentration (CMC). A series of column tests were performed to determine the breakthrough curves by using two different adsorbents: (1) Hydraffin CC 8 x 30 as a commercial granular activated carbon (GAC) and (2) Lewatit VPOC 1064 MD PH as a commercial organic polymer resin. In the experiments, the volumetric flow rate was maintained at 10.5 mL/min (approximately 2 m3/ m2 x h). Loading of adsorbents was continued until breakthrough was 10% of the feed concentration. The breakthrough took place at 488 bed volume (BV) below CMC (C0 = 40 mg/L) and 39 BV above CMC (C0 = 400 mg/ L) onto GAC. The organic polymer resin, however, showed a higher adsorption capacity than GAC (1412 BV below CMC and 287 BV above CMC). From the Logit method, the value of adsorption rate coefficient (K) and adsorption capacity coefficient (N) were obtained. PMID:20369564

  15. Preparation of a new adsorbent from activated carbon and carbon nanofiber (AC/CNF) for manufacturing organic-vacbpour respirator cartridge

    PubMed Central

    2013-01-01

    In this study a composite of activated carbon and carbon nanofiber (AC/CNF) was prepared to improve the performance of activated carbon (AC) for adsorption of volatile organic compounds (VOCs) and its utilization for respirator cartridges. Activated carbon was impregnated with a nickel nitrate catalyst precursor and carbon nanofibers (CNF) were deposited directly on the AC surface using catalytic chemical vapor deposition. Deposited CNFs on catalyst particles in AC micropores, were activated by CO2 to recover the surface area and micropores. Surface and textural characterizations of the prepared composites were investigated using Brunauer, Emmett and Teller’s (BET) technique and electron microscopy respectively. Prepared composite adsorbent was tested for benzene, toluene and xylene (BTX) adsorption and then employed in an organic respirator cartridge in granular form. Adsorption studies were conducted by passing air samples through the adsorbents in a glass column at an adjustable flow rate. Finally, any adsorbed species not retained by the adsorbents in the column were trapped in a charcoal sorbent tube and analyzed by gas chromatography. CNFs with a very thin diameter of about 10-20 nm were formed uniformly on the AC/CNF. The breakthrough time for cartridges prepared with CO2 activated AC/CNF was 117 minutes which are significantly longer than for those cartridges prepared with walnut shell- based activated carbon with the same weight of adsorbents. This study showed that a granular form CO2 activated AC/CNF composite could be a very effective alternate adsorbent for respirator cartridges due to its larger adsorption capacities and lower weight. PMID:23369424

  16. Soil cleanup by in-situ aeration. XX. Mass transport of volatile organics in wet activated carbon

    SciTech Connect

    Wilson, D.J.; Cordero, T.; Gomez-Lahoz, C.

    1994-10-01

    A mathematical model for the adsorption of volatile organic compounds (VOCs) from wet gas streams by granular activated carbon columns is developed, and modeling results are discussed. Capillary condensation of water in the carbon pores is found to have a very damaging effect on the rate of VOC adsorption, since diffusion rates of VOCs into the pores are greatly reduced. Implications of the results for the operation of soil vapor extraction systems for the remediation of hazardous waste sites are discussed, and suggestions are made on how to deal with the problem.

  17. Modeling adsorption rate of organic micropollutants present in landfill leachates onto granular activated carbon.

    PubMed

    Ocampo-Pérez, Raúl; Abdel daiem, Mahmoud M; Rivera-Utrilla, José; Méndez-Díaz, José D; Sánchez-Polo, Manuel

    2012-11-01

    The overall adsorption rate of single micropollutants present in landfill leachates such as phthalic acid (PA), bisphenol A (BPA), diphenolic acid (DPA), 2,4-dichlorophenoxy-acetic acid (2,4-D), and 4-chloro-2-methylphenoxyacetic acid (MCPA) on two commercial activated carbons was studied. The experimental data obtained were interpreted by using a diffusional model (PVSDM) that considers external mass transport, intraparticle diffusion, and adsorption on an active site. Furthermore, the concentration decay data were interpreted by using kinetics models. Results revealed that PVSDM model satisfactorily fitted the experimental data of adsorption rate on activated carbon. The tortuosity factor of the activated carbons used ranged from 2 to 4. The contribution of pore volume diffusion represented more than 92% of intraparticle diffusion confirming that pore volume diffusion is the controlling mechanism of the overall rate of adsorption and surface diffusion can be neglected. The experimental data were satisfactorily fitted the kinetic models. The second-order kinetic model was better fitted the experimental adsorption data than the first-order model. PMID:22858399

  18. The role of beaded activated carbon's pore size distribution on heel formation during cyclic adsorption/desorption of organic vapors.

    PubMed

    Jahandar Lashaki, Masoud; Atkinson, John D; Hashisho, Zaher; Phillips, John H; Anderson, James E; Nichols, Mark

    2016-09-01

    The effect of activated carbon's pore size distribution (PSD) on heel formation during adsorption of organic vapors was investigated. Five commercially available beaded activated carbons (BAC) with varying PSDs (30-88% microporous) were investigated. Virgin samples had similar elemental compositions but different PSDs, which allowed for isolating the contribution of carbon's microporosity to heel formation. Heel formation was linearly correlated (R(2)=0.91) with BAC micropore volume; heel for the BAC with the lowest micropore volume was 20% lower than the BAC with the highest micropore volume. Meanwhile, first cycle adsorption capacities and breakthrough times correlated linearly (R(2)=0.87 and 0.93, respectively) with BAC total pore volume. Micropore volume reduction for all BACs confirmed that heel accumulation takes place in the highest energy pores. Overall, these results show that a greater portion of adsorbed species are converted into heel on highly microporous adsorbents due to higher share of high energy adsorption sites in their structure. This differs from mesoporous adsorbents (low microporosity) in which large pores contribute to adsorption but not to heel formation, resulting in longer adsorbent lifetime. Thus, activated carbon with high adsorption capacity and high mesopore fraction is particularly desirable for organic vapor application involving extended adsorption/regeneration cycling. PMID:27173087

  19. Electrochemically active, crystalline, mesoporous covalent organic frameworks on carbon nanotubes for synergistic lithium-ion battery energy storage.

    PubMed

    Xu, Fei; Jin, Shangbin; Zhong, Hui; Wu, Dingcai; Yang, Xiaoqing; Chen, Xiong; Wei, Hao; Fu, Ruowen; Jiang, Donglin

    2015-01-01

    Organic batteries free of toxic metal species could lead to a new generation of consumer energy storage devices that are safe and environmentally benign. However, the conventional organic electrodes remain problematic because of their structural instability, slow ion-diffusion dynamics, and poor electrical conductivity. Here, we report on the development of a redox-active, crystalline, mesoporous covalent organic framework (COF) on carbon nanotubes for use as electrodes; the electrode stability is enhanced by the covalent network, the ion transport is facilitated by the open meso-channels, and the electron conductivity is boosted by the carbon nanotube wires. These effects work synergistically for the storage of energy and provide lithium-ion batteries with high efficiency, robust cycle stability, and high rate capability. Our results suggest that redox-active COFs on conducting carbons could serve as a unique platform for energy storage and may facilitate the design of new organic electrodes for high-performance and environmentally benign battery devices. PMID:25650133

  20. Electrochemically active, crystalline, mesoporous covalent organic frameworks on carbon nanotubes for synergistic lithium-ion battery energy storage

    PubMed Central

    Xu, Fei; Jin, Shangbin; Zhong, Hui; Wu, Dingcai; Yang, Xiaoqing; Chen, Xiong; Wei, Hao; Fu, Ruowen; Jiang, Donglin

    2015-01-01

    Organic batteries free of toxic metal species could lead to a new generation of consumer energy storage devices that are safe and environmentally benign. However, the conventional organic electrodes remain problematic because of their structural instability, slow ion-diffusion dynamics, and poor electrical conductivity. Here, we report on the development of a redox-active, crystalline, mesoporous covalent organic framework (COF) on carbon nanotubes for use as electrodes; the electrode stability is enhanced by the covalent network, the ion transport is facilitated by the open meso-channels, and the electron conductivity is boosted by the carbon nanotube wires. These effects work synergistically for the storage of energy and provide lithium-ion batteries with high efficiency, robust cycle stability, and high rate capability. Our results suggest that redox-active COFs on conducting carbons could serve as a unique platform for energy storage and may facilitate the design of new organic electrodes for high-performance and environmentally benign battery devices. PMID:25650133

  1. Evaluation of dispersion methods for enumeration of microorganisms from peat and activated carbon biofilters treating volatile organic compounds.

    PubMed

    Khammar, Nadia; Malhautier, Luc; Degrange, Valérie; Lensi, Robert; Fanlo, Jean-Louis

    2004-01-01

    To enumerate microorganisms having colonized biofilters treating volatile organic compounds, it is necessary firstly to evaluate dispersion methods. Crushing, shaking and sonication were then tested for the removal of microflora from biofilters packing materials (peat and activated carbon). Continuous or discontinuous procedures, and addition of glass beads had no effect on the number of microorganisms removed from peat particles. The duration of treatment also had no effect for shaking and crushing, but the number of microorganisms after 60 min of treatment with ultrasound was significantly higher than that obtained after 0.5 min. The comparison between these methods showed that crushing was the most efficient for the removal of microorganisms from both peat and activated carbon. The comparison between three chemical dispersion agents showed that 1% Na-pyrophosphate was less efficient, compared with 200 mM phosphate buffer or 1% Na-hexametaphosphate. To optimize the cultivation of microorganisms, three different agar media were compared. Tryptic soy agar tenfold diluted (TSA 1/10) was the most suitable medium for the culture of microflora from a peat biofilter. For the activated carbon biofilter, there was no significant difference between Luria Bertoni, TSA 1/10, and plate count agar. The optimized extraction and enumeration protocols were used to perform a quantitative characterization of microbial populations in an operating laboratory activated carbon biofilter and in two parallel peat biofilters. PMID:14575736

  2. Effects of coral reef benthic primary producers on dissolved organic carbon and microbial activity.

    PubMed

    Haas, Andreas F; Nelson, Craig E; Wegley Kelly, Linda; Carlson, Craig A; Rohwer, Forest; Leichter, James J; Wyatt, Alex; Smith, Jennifer E

    2011-01-01

    Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC) release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata--Ochrophyta; Amansia rhodantha--Rhodophyta; Halimeda opuntia--Chlorophyta), a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii) and a dominant hermatypic coral (Porites lobata). Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h⁻¹ dm⁻²), stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h⁻¹) and concomitant oxygen drawdown (0.16±0.05 µmol L⁻¹ h⁻¹ dm⁻²). Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence reef microbial

  3. Effects of Coral Reef Benthic Primary Producers on Dissolved Organic Carbon and Microbial Activity

    PubMed Central

    Haas, Andreas F.; Nelson, Craig E.; Wegley Kelly, Linda; Carlson, Craig A.; Rohwer, Forest; Leichter, James J.; Wyatt, Alex; Smith, Jennifer E.

    2011-01-01

    Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC) release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata – Ochrophyta; Amansia rhodantha – Rhodophyta; Halimeda opuntia – Chlorophyta), a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii) and a dominant hermatypic coral (Porites lobata). Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h−1 dm−2), stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h−1) and concomitant oxygen drawdown (0.16±0.05 µmol L−1 h−1 dm−2). Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence reef

  4. Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of Cloud Condensation Nuclei (CCN)

    NASA Astrophysics Data System (ADS)

    Kuwata, M.; Shao, W.; Lebouteiller, R.; Martin, S. T.

    2013-05-01

    The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic, and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69-0.72) and α-pinene-derived SOM (O : C = 0.38-0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the difference in the behavior of α-pinene-derived SOM compared to that of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e., insoluble regime) whereas those dominated by oxygenated organic components activate (i.e., highly soluble regime) for typical atmospheric cloud life cycles.

  5. Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of cloud condensation nuclei (CCN)

    NASA Astrophysics Data System (ADS)

    Kuwata, M.; Shao, W.; Lebouteiller, R.; Martin, S. T.

    2012-12-01

    The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69-0.72) and α-pinene-derived SOM (O : C = 0.38-0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the differences of α-pinene-derived SOM compared to the behavior of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e. insoluble regime) whereas those dominated by oxygenated organic components activate (i.e. highly soluble regime).

  6. Evaluation of biochars and activated carbons for in situ remediation of sediments impacted with organics, mercury, and methylmercury.

    PubMed

    Gomez-Eyles, Jose L; Yupanqui, Carmen; Beckingham, Barbara; Riedel, Georgia; Gilmour, Cynthia; Ghosh, Upal

    2013-12-01

    In situ amendment of activated carbon (AC) to sediments can effectively reduce the bioavailability of hydrophobic organic contaminants. While biochars have been suggested as low-cost and sustainable alternatives to ACs, there are few comparative sorption data especially for mercury (Hg) and methylmercury (MeHg) at the low porewater concentrations in sediments. Here we compare the ability of a wide range of commercially available and laboratory synthesized ACs and biochars to sorb PAHs, PCBs, DDTs, inorganic Hg, and MeHg at environmentally relevant concentrations. Compared to natural organic matter, sorption capacity for most organic compounds was at least 1-2 orders of magnitude higher for unactivated biochars and 3-4 orders of magnitude higher for ACs which translated to sediment porewater PCB concentration reductions of 18-80% for unactivated biochars, and >99% for ACs with 5% by weight amendment to sediment. Steam activated carbons were more effective than biochars in Hg sorption and translated to modeled porewater Hg reduction in the range of 94-98% for sediments with low native Kd and 31-73% for sediments with high native Kd values for Hg. Unactivated biochars were as effective as the steam activated carbons for MeHg sorption. Predicted reductions of porewater MeHg were 73-92% for sediments with low native Kd and 57-86% for sediment with high native K(d). ACs with high surface areas therefore are likely to be effective in reducing porewater concentrations of organics, Hg, and MeHg in impacted sediments. Unactivated biochars had limited effectiveness for organics and Hg but can be considered when MeHg exposure is the primary concern. PMID:24168448

  7. Effects of Human Activities on the Composition of Organic Carbon in Estuaries: Insights Gained Through Lipid Biomarker Studies

    NASA Astrophysics Data System (ADS)

    Canuel, E. A.

    2002-12-01

    Applications of organic geochemistry have expanded in recent decades to include studies within fields as diverse as ecology and ecosystem science, biogeochemistry, and environmental geochemistry. In part, this expansion has occurred in response to increasing human impacts on the environment which are manifested to a large extent in freshwater and estuarine environments. Human influences to these regions include alterations in carbon and nutrient flow, changes in sedimentation and the introduction of industrial and petroleum products. Organic geochemists bring new tools and insights to these areas improving our ability to trace specific components of organic matter. These approaches have the capacity to improve our understanding of the role nearshore regions play in the global carbon cycle, better identification of the sources and mode of delivery of natural and anthropogenic organic molecules, and an improved understanding of the fate of organic molecules including remineralization, transformation, or burial in sediments. Chesapeake Bay and San Francisco Bay are the largest estuaries in the continental U.S.A. and provide an interesting comparison for understanding processes influencing the composition of estuarine particulate organic matter (POM). Both estuaries have also been heavily impacted by human activities thus providing an opportunity to investigate how anthropogenic activities influence POM quantity and quality. Results from biomarker analysis of suspended POM and surficial sediments collected from each estuary will be presented and summarized in this talk. Stable isotopic signatures and lipid biomarker compounds reveal spatial variations in organic matter sources along the salinity continuum of each estuary with a stronger terrigeneous signature at the freshwater end-member. In addition, temporal variations in freshwater inflow and phytoplankton production influenced the sources and reactivity of POM. This talk will demonstrate that results from biomarker

  8. The effects of tree rhizodeposition on soil exoenzyme activity, dissolved organic carbon, and nutrient availability in a subalpine forest ecosystem.

    PubMed

    Weintraub, Michael N; Scott-Denton, Laura E; Schmidt, Steven K; Monson, Russell K

    2007-11-01

    Previous studies have found that root carbon inputs to the soil can stimulate the mineralization of existing soil carbon (C) pools. It is still uncertain, however, whether this "primed" C is derived from elevated rates of soil organic matter (SOM) decomposition, greater C release from microbial pools, or both. The goal of this research was to determine how the activities of the microbial exoenzymes that control SOM decomposition are affected by root C inputs. This was done by manipulating rhizodeposition with tree girdling in a coniferous subalpine forest in the Rocky Mountains of Colorado, USA, and following changes in the activities of nine exoenzymes involved in decomposition, as well as soil dissolved organic C, dissolved organic and inorganic nitrogen (N), and microbial biomass C and N. We found that rhizodeposition is high in the spring, when the soils are still snow-covered, and that there are large ephemeral populations of microorganisms dependent upon this C. Microbial N acquisition from peptide degradation increased with increases in microbial biomass when rhizodeposition was highest. However, our data indicate that the breakdown of cellulose, lignin, chitin, and organic phosphorus are not affected by springtime increases in soil microbial biomass associated with increases in rhizodeposition. We conclude that the priming of soil C mineralization by rhizodeposition is due to growth of the microbial biomass and an increase in the breakdown of N-rich proteins, but not due to increases in the degradation of plant litter constituents such as cellulose and lignin. PMID:17657512

  9. Modeling the heat and mass transfers in temperature-swing adsorption of volatile organic compounds onto activated carbons

    SciTech Connect

    Sylvain Giraudet; Pascaline Pre; Pierre Le Cloirec

    2009-02-15

    A theoretical model was built to simulate the adsorption of volatile organic compounds (VOCs) onto activated carbons in a fixed bed. This model was validated on a set of experimental data obtained for the adsorption of acetone, ethyl formate, and dichloromethane onto five commercial activated carbons. The influence of operating conditions was modeled with various VOC contents at the inlet of the adsorber and superficial velocities of the gas-phase from 0.14 to 0.28 m.s{sup -1}. Breakthrough times and maximum temperature rises were computed with a coefficient of determination of 0.988 and 0.901, respectively. The simulation was then extended to the adsorption of mixtures of VOCs. From the comparison of simulation and experimental results, the advantage of accounting for dispersions of heat and mass is shown and the importance in taking into account the temperature effect on the equilibrium data is demonstrated. 29 refs., 6 figs., 1 tab.

  10. Where to dose powdered activated carbon in a wastewater treatment plant for organic micro-pollutant removal.

    PubMed

    Streicher, Judith; Ruhl, Aki Sebastian; Gnirß, Regina; Jekel, Martin

    2016-08-01

    Emissions of many organic micro-pollutants (OMP) into the aquatic environment can be efficiently reduced with advanced treatment at wastewater treatment plants (WWTP). Post-treatment with activated carbon is currently considered as one of the most promising options, but powdered activated carbon (PAC) could also be dosed into the existing biological treatment process instead. Due to much greater concentrations of suspended and dissolved constituents the adsorptive OMP removal was expected to be severely hindered. Systematic comparative adsorption tests with samples from different process steps of a large conventional WWTP were conducted to investigate differences in adsorption competition and removal efficiencies. The results show that much greater competition occurs in the WWTP influent and in the anaerobic tank but removal efficiencies in the anoxic and aerobic tank and in the WWTP effluent were more similar than expected. Suspended solids thus seem not to severely affect OMP adsorption. Similar results were obtained in a comparison of different commercial PAC in all for the respective matrices. OMP removals showed a relation with the PAC dosage normalized to the concentration of dissolved organic carbon. In the anoxic and aerobic tank and in the WWTP effluent, a uniform correlation of OMP removals and reductions of UV light absorption was observed. PMID:27174820

  11. Characteristics of competitive adsorption between 2-methylisoborneol and natural organic matter on superfine and conventionally sized powdered activated carbons.

    PubMed

    Matsui, Yoshihiko; Yoshida, Tomoaki; Nakao, Soichi; Knappe, Detlef R U; Matsushita, Taku

    2012-10-01

    When treating water with activated carbon, natural organic matter (NOM) is not only a target for adsorptive removal but also an inhibitory substance that reduces the removal efficiency of trace compounds, such as 2-methylisoborneol (MIB), through adsorption competition. Recently, superfine (submicron-sized) activated carbon (SPAC) was developed by wet-milling commercially available powdered activated carbon (PAC) to a smaller particle size. It was reported that SPAC has a larger NOM adsorption capacity than PAC because NOM mainly adsorbs close to the external adsorbent particle surface (shell adsorption mechanism). Thus, SPAC with its larger specific external surface area can adsorb more NOM than PAC. The effect of higher NOM uptake on the adsorptive removal of MIB has, however, not been investigated. Results of this study show that adsorption competition between NOM and MIB did not increase when NOM uptake increased due to carbon size reduction; i.e., the increased NOM uptake by SPAC did not result in a decrease in MIB adsorption capacity beyond that obtained as a result of NOM adsorption by PAC. A simple estimation method for determining the adsorbed amount of competing NOM (NOM that reduces MIB adsorption) is presented based on the simplified equivalent background compound (EBC) method. Furthermore, the mechanism of adsorption competition is discussed based on results obtained with the simplified EBC method and the shell adsorption mechanism. Competing NOM, which likely comprises a small portion of NOM, adsorbs in internal pores of activated carbon particles as MIB does, thereby reducing the MIB adsorption capacity to a similar extent regardless of adsorbent particle size. SPAC application can be advantageous because enhanced NOM removal does not translate into less effective removal of MIB. Molecular size distribution data of NOM suggest that the competing NOM has a molecular weight similar to that of the target compound. PMID:22763287

  12. Selection of pecan shell based activated carbons for removal of organic and inorganic impurities from simulated well-water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Activated carbons are a byproduct from pyrolysis and have value as a purifying agent. The effectiveness of activated carbons is dependent on feedstock selection and pyrolysis conditions that modify its surface properties. Therefore, pecan shell-based activated carbons (PSACs) were prepared by soakin...

  13. Bioturbation and dissolved organic matter enhance contaminant fluxes from sediment treated with powdered and granular activated carbon.

    PubMed

    Kupryianchyk, D; Noori, A; Rakowska, M I; Grotenhuis, J T C; Koelmans, A A

    2013-05-21

    Sediment amendment with activated carbon (AC) is a promising technique for in situ sediment remediation. To date it is not clear whether this technique sufficiently reduces sediment-to-water fluxes of sediment-bound hydrophobic organic chemicals (HOCs) in the presence of bioturbators. Here, we report polychlorobiphenyl (PCB) pore water concentrations, fluxes, mass transfer coefficients, and survival data of two benthic species, for four treatments: no AC addition (control), powdered AC addition, granular AC addition and addition and subsequent removal of GAC (sediment stripping). AC addition decreased mass fluxes but increased apparent mass transfer coefficients because of dissolved organic carbon (DOC) facilitated transport across the benthic boundary layer (BBL). In turn, DOC concentrations depended on bioturbator activity which was high for the PAC tolerant species Asellus aquaticus and low for AC sensitive species Lumbriculus variegatus. A dual BBL resistance model combining AC effects on gradients, DOC facilitated transport and biodiffusion was evaluated against the data and showed how the type of resistance differs with treatment and chemical hydrophobicity. Data and simulations illustrate the complex interplay between AC and contaminant toxicity to benthic organisms and how differences in species tolerance affect mass fluxes from sediment to the water column. PMID:23590290

  14. Comparing and modeling organic micro-pollutant adsorption onto powdered activated carbon in different drinking waters and WWTP effluents.

    PubMed

    Zietzschmann, Frederik; Aschermann, Geert; Jekel, Martin

    2016-10-01

    The adsorption of organic micro-pollutants (OMP) onto powdered activated carbon (PAC) was compared between regionally different waters within two groups, namely five drinking waters and seven wastewater treatment plant (WWTP) effluents. In all waters, OMP were spiked to adjust similar ratios of the initial OMP and DOC concentrations (c0,OMP/c0,DOC). PAC was dosed specific to the respective DOC (e.g. 2 mg PAC/per mg DOC). Liquid chromatography with online carbon detection shows differences of the background organic matter (BOM) compositions. The OMP removals at given DOC-specific PAC doses vary by ±15% (drinking waters) and ±10% (WWTP effluents). Similar BOM-induced adsorption competition in the waters of the respective group results in overall relationships between the PAC loadings and the liquid phase concentrations of each OMP (in the case of strong adsorbates). Weaker adsorbates show no overall relationships because of the strong BOM-induced adsorption competition near the initial OMP concentration. Correlations between OMP removals and UV254 removals were independent of the water (within the respective group). The equivalent background compound (EBC) model was applied to the experimental data. Using global EBC Freundlich coefficients, the initial EBC concentration correlates with the DOC (both water groups separately) and the low molecular weight (LMW) organics concentrations (all waters combined). With these correlations, the EBC could be initialized by using the DOC or the LMW organics concentration of additional drinking water, WWTP effluent, and surface water samples. PMID:27344250

  15. Total organic carbon analyzer

    NASA Technical Reports Server (NTRS)

    Godec, Richard G.; Kosenka, Paul P.; Smith, Brian D.; Hutte, Richard S.; Webb, Johanna V.; Sauer, Richard L.

    1991-01-01

    The development and testing of a breadboard version of a highly sensitive total-organic-carbon (TOC) analyzer are reported. Attention is given to the system components including the CO2 sensor, oxidation reactor, acidification module, and the sample-inlet system. Research is reported for an experimental reagentless oxidation reactor, and good results are reported for linearity, sensitivity, and selectivity in the CO2 sensor. The TOC analyzer is developed with gravity-independent components and is designed for minimal additions of chemical reagents. The reagentless oxidation reactor is based on electrolysis and UV photolysis and is shown to be potentially useful. The stability of the breadboard instrument is shown to be good on a day-to-day basis, and the analyzer is capable of 5 sample analyses per day for a period of about 80 days. The instrument can provide accurate TOC and TIC measurements over a concentration range of 20 ppb to 50 ppm C.

  16. An investigation of groundwater organics, soil minerals, and activated carbon on the complexation, adsorption, and separation of technetium-99

    SciTech Connect

    Gu, B.; Dowlen, K.E.

    1996-01-01

    This report summarizes studies on the interactions of technetium-99 (Tc) with different organic compounds and soil minerals under both oxidizing and reducing conditions. The report is divided into four parts and includes (1) effect of natural organic matter (NOM) on the complexation and solubility of Tc, (2) complexation between Tc and trichloroethylene (TCE) in aqueous solutions, (3) adsorption of Tc on soil samples from Paducah Gaseous Diffusion Plant (PGDP), and (4) adsorption and separation of Tc on activated carbon. Various experimental techniques were applied to characterize and identify Tc complexation with organic compounds and TCE, including liquid-liquid extraction, membrane filtration, size exclusion, and gel chromatography. Results indicate, within the experimental error, Tc (as pertechnetate, TcO{sub 4}) did not appear to form complexes with groundwater or natural organic matter under both atmospheric and reducing conditions. However, Tc can form complexes with certain organic compounds or specific functional groups such as salicylate. Tc did not appear to form complexes with TCE in aqueous solution.Both liquid-liquid extraction and high performance liquid chromatography (HPLC) gave no indication Tc was complexed with TCE. The correlations between Tc and TCE concentrations in monitoring wells at PGDP may be a coincidence because TCE was commonly used as a decontamination reagent. Once TCE and Tc entered the groundwater, they behaved similarly because both TcO{sub 4}{sup {minus}} and TCE are poorly adsorbed by soils. An effective remediation technique to remove TcO{sub 4}{sup {minus}} from PGDP contaminated groundwater is needed. One possibility is the use of an activated carbon adsorption technique developed in this study.

  17. Dynamics of soil organic carbon and microbial activity in treated wastewater irrigated agricultural soils along soil profiles

    NASA Astrophysics Data System (ADS)

    Jüschke, Elisabeth; Marschner, Bernd; Chen, Yona; Tarchitzky, Jorge

    2010-05-01

    Treated wastewater (TWW) is an important source for irrigation water in arid and semiarid regions and already serves as an important water source in Jordan, the Palestinian Territories and Israel. Reclaimed water still contains organic matter (OM) and various compounds that may effect microbial activity and soil quality (Feigin et al. 1991). Natural soil organic carbon (SOC) may be altered by interactions between these compounds and the soil microorganisms. This study evaluates the effects of TWW irrigation on the quality, dynamics and microbial transformations of natural SOC. Priming effects (PE) and SOC mineralization were determined to estimate the influence of TWW irrigation on SOC along soil profiles of agricultural soils in Israel and the Westbank. The used soil material derived from three different sampling sites allocated in Israel and The Palestinian Authority. Soil samples were taken always from TWW irrigated sites and control fields from 6 different depths (0-10, 10-20, 20-30, 30-50, 50-70, 70-100 cm). Soil carbon content and microbiological parameters (microbial biomass, microbial activities and enzyme activities) were investigated. In several sites, subsoils (50-160 cm) from TWW irrigated plots were depleted in soil organic matter with the largest differences occurring in sites with the longest TWW irrigation history. Laboratory incubation experiments with additions of 14C-labelled compounds to the soils showed that microbial activity in freshwater irrigated soils was much more stimulated by sugars or amino acids than in TWW irrigated soils. The lack of such "priming effects" (Hamer & Marschner 2005) in the TWW irrigated soils indicates that here the microorganisms are already operating at their optimal metabolic activity due to the continuous substrate inputs with soluble organic compounds from the TWW. The fact that PE are triggered continuously due to TWW irrigation may result in a decrease of SOC over long term irrigation. Already now this could be

  18. [Effects of grazing disturbance on soil active organic carbon in mountain forest-arid valley ecotone in the upper reaches of Minjiang River].

    PubMed

    Liu, Shan-Shan; Zhang, Xing-Hua; Gong, Yuan-Bo; Li, Yuan; Wang, Yan; Yin, Yan-Jie; Ma, Jin-Song; Guo, Ting

    2014-02-01

    Effects of grazing disturbance on the soil carbon contents and active components in the four vegetations, i.e., artificial Robinia pseudoacacia plantation, artificial poplar plantation, Berberis aggregate shrubland and grassland, were studied in the mountain forest-arid valley ecotone in the upper Minjiang River. Soil organic carbon and active component contents in 0-10 cm soil layer were greater than in 10-20 cm soil layer at each level of grazing disturbance. With increasing the grazing intensity, the total organic carbon (TOC), light fraction organic carbon (LFOC), particulate organic carbon (POC) and easily oxidized carbon (LOC) contents in 0-10 cm soil layer decreased gradually in the artificial R. pseudoacacia plantation. The LFOC content decreased, the POC content increased, and the TOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the artificial poplar plantation. The POC content decreased, and the TOC, LFOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the B. aggregate shrubland. The POC and TOC contents decreased, and the LFOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the grassland. The decreasing ranges of LOC, LFOC and POC contents were 0.1-7.9 times more than that of TOC content. There were significant positive relationships between TOC and LOC, LFOC and POC, suggesting that the active organic carbon components could reflect the change of soil total carbon content. PMID:24830233

  19. Modeling nonequilibrium adsorption of MIB and sulfamethoxazole by powdered activated carbon and the role of dissolved organic matter competition.

    PubMed

    Shimabuku, Kyle K; Cho, Hyukjin; Townsend, Eli B; Rosario-Ortiz, Fernando L; Summers, R Scott

    2014-12-01

    This study demonstrates that the ideal adsorbed solution theory-equivalent background compound (IAST-EBC) as a stand-alone model can simulate and predict the powdered activated carbon (PAC) adsorption of organic micropollutants found in drinking water sources in the presence of background dissolved organic matter (DOM) under nonequilibrium conditions. The IAST-EBC represents the DOM competitive effect as an equivalent background compound (EBC). When adsorbing 2-methylisoborneol (MIB) with PAC, the EBC initial concentration was a similar percentage, on average 0.51%, of the dissolved organic carbon in eight nonwastewater impacted surface waters. Using this average percentage in the IAST-EBC model yielded good predictions for MIB removal in two nonwastewater impacted waters. The percentage of competitive DOM was significantly greater in wastewater impacted surface waters, and varied markedly in DOM size fractions. Fluorescence parameters exhibited a strong correlation with the percentage of competitive DOM in these waters. Utilizing such correlations in the IAST-EBC successfully modeled MIB and sulfamethoxazole adsorption by three different PACs in the presence of DOM that varied in competitive effect. The influence of simultaneous coagulant addition on PAC adsorption of micropollutants was also investigated. Coagulation caused the DOM competitive effect to increase and decrease with MIB and sulfamethoxazole, respectively. PMID:25371136

  20. Combining Coagulation/MIEX with Biological Activated Carbon Treatment to Control Organic Fouling in the Microfiltration of Secondary Effluent.

    PubMed

    Pramanik, Biplob Kumar; Roddick, Felicity A; Fan, Linhua

    2016-01-01

    Coagulation, magnetic ion exchange resin (MIEX) and biological activated carbon (BAC) were examined at lab scale as standalone, and sequential pre-treatments for controlling the organic fouling of a microfiltration membrane by biologically treated secondary effluent (BTSE) using a multi-cycle approach. MIEX gave slightly greater enhancement in flux than coagulation due to greater removal of high molecular weight (MW) humic substances, although it was unable to remove high MW biopolymers. BAC treatment was considerably more effective for improving the flux than coagulation or MIEX. This was due to the biodegradation of biopolymers and/or their adsorption by the biofilm, and adsorption of humic substances by the activated carbon, as indicated by size exclusion chromatography. Coagulation or MIEX followed by BAC treatment further reduced the problematic foulants and significantly improved the flux performance. The unified membrane fouling index showed that the reduction of membrane fouling by standalone BAC treatment was 42%. This improved to 65%, 70%, and 93% for alum, ferric chloride and MIEX pre-treatment, respectively, when followed by BAC treatment. This study showed the potential of sequential MIEX and BAC pre-treatment for controlling organic fouling and thus enhancing the performance of microfiltration in the reclamation of BTSE. PMID:27483327

  1. Potential Impact of Microbial Activity on the Oxidant Capacity and the Organic Carbon Budget in Clouds (Invited)

    NASA Astrophysics Data System (ADS)

    Delort, A.

    2013-12-01

    Within cloud water, microorganisms are metabolically active; so they are suspected to contribute to atmospheric chemistry. This paper is focused on the interactions between microorganisms and Reactive Oxygenated Species present in cloud water since these chemical compounds are driving the oxidant capacity of the cloud system. For this, real cloud waters with contrasting features (marine, continental, urban) were sampled at the puy de Dôme mountain (France). They exhibit high microbial biodiversity and complex chemical composition. These media were incubated in the dark and subjected to UV-light radiation in specifically designed photo-bio-reactors. The concentrations of hydrogen peroxide (H2O2), organic compounds and the ATP/ADP ratio were monitored during the incubation period. Microorganisms remained metabolically active in the presence of hydroxyl radicals photo-produced from H2O2. This oxidant and major carbon compounds (formaldehyde and carboxylic acids) were biodegraded by the endogenous microflora. This work suggests that microorganisms could play a double role in atmospheric chemistry: first, they could directly metabolize organic carbon species; second they could reduce the available source of radicals due to their oxidative metabolism. Consequently, molecules such as H2O2 would be no longer available for photochemical or other chemical reactions, decreasing the cloud oxidant capacity.

  2. Climate effect on soil enzyme activities and dissolved organic carbon in mountain calcareous soils: a soil-transplant experiment

    NASA Astrophysics Data System (ADS)

    Puissant, Jérémy; Cécillon, Lauric; Mills, Robert T. E.; Gavazov, Konstantin; Robroek, Bjorn J. M.; Spiegelberger, Thomas; Buttler, Alexandre; Brun, Jean-Jacques

    2013-04-01

    Mountain soils store huge amounts of carbon as soil organic matter (SOM) which may be highly vulnerable to the strong climate changes that mountain areas currently experience worldwide. Climate modifications are expected to impact microbial activity which could change the rate of SOM decomposition/accumulation, thereby questioning the net C source/sink character of mountain soils. To simulate future climate change expected in the 21st century in the calcareous pre-Alps, 15 blocks (30 cm deep) of undisturbed soil were taken from a mountain pasture located at 1400 m a.s.l. (Marchairuz, Jura, Switzerland) and transplanted into lysimeters at the same site (control) and at two other sites located at 1000 m a.s.l. and 600 m a.s.l. (5 replicates per site). This transplantation experiment which started in 2009 simulates a climate warming with a temperature increase of 4° C and a decreased humidity of 40 % at the lowest site. In this study, we used soil extracellular enzyme activities (EEA) as functional indicators of SOM decomposition to evaluate the effect of climate change on microbial activity and SOM dynamics along the seasons. Dissolved organic carbon (DOC) was also measured to quantify the assimilable carbon for microorganism. In autumn 2012, a first sampling step out of four (winter, spring and summer 2013) has been realized. We extracted 15 cm deep soil cores from each transplant (x15) and measured (i) DOC and (ii) the activities of nine different enzymes. Enzymes were chosen to represent the degradation of the most common classes of biogeochemical compounds in SOM. β-glucosidase, β-D-cellubiosidase, β-Xylosidase, N-acetyl-β-glucosaminidase, leucine aminopeptidase, lipase, phenoloxidase respectively represented the degradation of sugar, cellulose, hemicellulose, chitin, protein, lipid and lignin. Moreover, the fluorescein diacetate (FDA) hydrolysis was used to provide an estimate of global microbial activity and phosphatase was used to estimate phosphorus

  3. Comparison of dissolved-organic-carbon residuals from air- and pure-oxygen-activated-sludge sequencing-batch reactors.

    PubMed

    Esparza-Soto, Mario; Fox, Peter; Westerhoff, Paul

    2006-03-01

    Literature shows that full-scale pure-oxygen activated sludge (O2-AS) wastewater treatment plants (WWTPs) generate effluents with higher dissolved-organic carbon (DOC) concentrations and larger high-molecular-weight fractions compared to air-activated-sludge (Air-AS) WWTP effluents. The purpose of this paper was to evaluate how gas supplied (air vs. pure oxygen) to sequencing-batch reactors affected DOC transformations. The main conclusions of this paper are (a) O2-AS effluent DOC is more refractory than air-AS effluent DOC; and (b) O2-AS systems may have higher five-day biochemical oxygen demand removals than air-AS systems; however, in terms of COD and DOC removal, air-AS systems are better than O2-AS systems. Analysis of a database from side-by-side O2- and air-AS pilot tests from literature supported these observations. PMID:16629273

  4. CORRELATIONS FOR THE DETERMINATION OF SURFACE DIFFUSIVITIES OF ORGANIC CHEMICALS ADSORBED ONTO GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Differential column batch reactor (DCBR) experiments in organic-free water were conducted for the following volatile organic compounds (VOCs): trichloroethene, tetrachloroethene, cis-1,2 dichlorethene, and toluene. Surface diffusion was required to explain the rate of uptake for ...

  5. Activation of carbon-hydrogen bonds in alkanes and other organic molecules using organotransition metal complexes

    SciTech Connect

    Bergman, R.G.

    1991-10-01

    We have recently begun to investigate the interaction of C-H activating iridium and rhodium complexes with functionalized organic molecules, to determine the effect of functional groups on the process, as well as to investigate the propensity of Ir and Rh to insert into C-H versus other types of X-H bonds. Recent experiments have demonstrated that xenon liquefied at -70{degrees}C and 10 atm pressure serves as an inert solvent for the C-H oxidative addition reaction. We have been able to prepare and isolate, for the first time, C-H oxidative addition products formed from high-melting solid substrates such as naphthalene, adamantane, and even cubane; the latter case represents the first observation of C-H oxidative addition at a tertiary C-H bond. Liquid xenon has also allowed us to carry out more conveniently the C-H oxidative addition reactions of low-boiling gases that are difficult to liquefy, such as methane. Recently we have also been able to carry out analogous studies in the gas phase. Under these conditions, ``naked`` rather than solvated Cp*Rh(CO) is formed, and this species reacts with cyclohexane at nearly gas-kinetic rates. Under the conditions, collision between Cp*Rh(CO) and cyclohexane is the slowest step in the overall C-H activation process. In contrast, in solution association of solvent with free Cp*Rh(CO) is so rapid that the step involving C-H bond cleavage in the coordinated alkane complex becomes rate-determining. 3 refs., 5 figs.

  6. Activation of carbon-hydrogen bonds in alkanes and other organic molecules using organotransition metal complexes

    SciTech Connect

    Bergman, R.G.

    1991-10-01

    We have recently begun to investigate the interaction of C-H activating iridium and rhodium complexes with functionalized organic molecules, to determine the effect of functional groups on the process, as well as to investigate the propensity of Ir and Rh to insert into C-H versus other types of X-H bonds. Recent experiments have demonstrated that xenon liquefied at -70{degrees}C and 10 atm pressure serves as an inert solvent for the C-H oxidative addition reaction. We have been able to prepare and isolate, for the first time, C-H oxidative addition products formed from high-melting solid substrates such as naphthalene, adamantane, and even cubane; the latter case represents the first observation of C-H oxidative addition at a tertiary C-H bond. Liquid xenon has also allowed us to carry out more conveniently the C-H oxidative addition reactions of low-boiling gases that are difficult to liquefy, such as methane. Recently we have also been able to carry out analogous studies in the gas phase. Under these conditions, naked'' rather than solvated Cp*Rh(CO) is formed, and this species reacts with cyclohexane at nearly gas-kinetic rates. Under the conditions, collision between Cp*Rh(CO) and cyclohexane is the slowest step in the overall C-H activation process. In contrast, in solution association of solvent with free Cp*Rh(CO) is so rapid that the step involving C-H bond cleavage in the coordinated alkane complex becomes rate-determining. 3 refs., 5 figs.

  7. Altered soil organic carbon stability in eastern deciduous forest: interplay between forest successional Stage and invasive earthworm activity

    NASA Astrophysics Data System (ADS)

    Ma, Y.; Filley, T. R.; McCormick, M.; Szlavecz, K. A.

    2012-12-01

    Detritivore -mediated decomposition and incorporation of aboveground litter is an important processes in soil carbon cycle of forest ecosystems that can be a major control on the proportion of stable and unstable soil carbon pools. We investigated how earthworm activity interacts with litter type to alter the stability of soil organic carbon (SOC) in an eastern deciduous successional forest within at the Smithsonian Environmental Research Center (SERC). Soil C and N content and chemistry (lignin and fatty acids) among particulate and mineral-bound fractions was shifted after 5 years of litter (wood and leaf) addition but with significant differences among the forest successional stages and with earthworm activity. Results from a 6 month laboratory incubation (25°C and 15°C) of bulk soil samples taken from the treatments and incubated at 25°C and 15°C demonstrate that litter addition type and earthworm activity interacted to control the proportion of labile and stable carbon. Specifically, the labile C pools in double wood and control treatments were highest in young successional forest with higher earthworm activity. However, in the double leaf treatment, the labile C pool was higher in old successional forests with less worm activity. In general, the stable C pool, released after one month, was higher in old successional forests for all three treatments. The difference of the stable pool between young and old successional forest was the largest with double wood treatment, followed by control treatment and the lowest with double leaf treatment. In summary, wood treatment shifted SOC pool to relatively more stable pool in old successional forests decreasing labile C pool but not the young sites. While double leaf treatment increased the labile pool in old forests but in young successional forests, SOC shifted to relatively more stable pool by decreasing the labile pool and increasing the stable pool. This result indicates that the type of aboveground litter

  8. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland

    EPA Science Inventory

    Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolve...

  9. Characterising low molecular weight dissolved organic carbon compounds in subglacial systems; implications for subglacial metabolic activity and potential downstream export

    NASA Astrophysics Data System (ADS)

    Lawson, Emily; Wadham, Jemma; Lis, Grzegorz; Telling, Jon

    2010-05-01

    Glaciers and ice sheets represent ~10% of the contemporary global surface coverage, yet remain one of the least explored sectors of the Earth's biosphere. The basal regions of these ice masses, known as subglacial environments, are capable of harbouring a diverse range of microorganisms that are often metabolically active despite the lack of sunlight, the cold temperatures and nutrient scarcity. Here, we consider the potential for such environments to be active components of the Earth's biogeochemical cycles. Subglacial environments have traditionally been excluded from global carbon budgets because they were assumed to be predominantly abiotic. Organic carbon (OC) reservoirs and transformations were also believed to be limited. However, significant stores of bioavailable carbon are thought to be present in glacially-overridden material, providing a potential substrate for in situ microbial metabolism. We examine the molecular characteristics of dissolved OC in basal ice and subglacial runoff from two glacier/ice-sheet systems with contrasting organic carbon substrates; Russell/Leverett Glacier, Greenland ice sheet, and Engabreen, Norway, to determine the range of dissolved low molecular weight OC (LMWOC) compounds and their relative bioavailability. Overridden material beneath the Greenland ice sheet is relatively young and organic-rich, contrasting with the older crystalline bedrock/continental shield that was overridden during glaciation at Engabreen. We first utilise a combination of fluorescence spectroscopy and ion chromatography to identify and quantify volatile fatty acids, carbohydrates and amino acids in basal ice. Volatile fatty acids are key metabolic substrates and their provision is thought to be a primary control on subglacial metabolic activity. We then provide a temporal record of amino acids and carbohydrates in subglacial runoff from Leverett Glacier (June 23rd - August 18th 2009), and compare this with subglacial runoff from Engabreen (2008 melt

  10. The effect of water temperature on the adsorption equilibrium of dissolved organic matter and atrazine on granular activated carbon

    SciTech Connect

    Bernd Schreiber; Viktor Schmalz; Thomas Brinkmann; Eckhard Worch

    2007-09-15

    The influence of water temperature on the adsorption of natural dissolved organic matter (DOM) on activated carbon has not been investigated intensively yet. In this study, batch experiments with granular activated carbon (GAC) F300, from bituminous coal, have been carried out at three temperatures (5, 20, 35{sup o} C) using a humic acid model water and different types of surface water (lake, river, canal). Furthermore, the adsorption of an anthropogenic contaminant, atrazine, was quantified in the absence and presence of DOM. The results indicate a significant influence of water temperature on the adsorption equilibrium of DOM and atrazine. Contrary to expectations, DOM and atrazine adsorption in surface water tends to be increased with increasing water temperature, whereas the extent of this effect is dependent on the type and concentration of DOM. Furthermore, the temperature effect on atrazine adsorption is controlled by competition of DOM and atrazine on adsorption sites. Some assumptions are proposed and discussed for explaining the temperature effects observed in the batch studies. 39 refs., 4 figs., 2 tabs.

  11. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-10-01

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist.

  12. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence

    PubMed Central

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-01-01

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist. PMID:26503629

  13. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence.

    PubMed

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-01-01

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist. PMID:26503629

  14. Effects of Natural Organic Matter on PCB-Activated Carbon Sorption Kinetics: Implications for Sediment Capping Applications

    EPA Science Inventory

    In-situ capping of polychlorinated biphenyl (PCB) contaminated sediments with layers of sorbents such as activated carbon has been proposed, but several technical questions remain regarding long-term effectiveness. An activated carbon amended sediment cap was mimicked in laborat...

  15. Ozonation effect on natural organic matter adsorption and biodegradation--application to a membrane bioreactor containing activated carbon for drinking water production.

    PubMed

    Treguer, Ronan; Tatin, Romuald; Couvert, Annabelle; Wolbert, Dominique; Tazi-Pain, Annie

    2010-02-01

    More stringent legislation on dissolved organic matter (DOM) urges the drinking water industry to improve in DOM removal, especially when applied to water with high dissolved organic carbon (DOC) contents and low turbidity. To improve conventional processes currently used in drinking water treatment plants (DWTPs), the performances of a hybrid membrane bioreactor containing fluidized activated carbon were investigated at the DWTP of Rennes. Preliminary results showed that the residual DOC was the major part of the non-biodegradable fraction. In order to increase the global efficiency, an upstream oxidation step was added to the process. Ozone was chosen to break large molecules and increase their biodegradability. The first step consisted of carrying out lab-scale experiments in order to optimise the necessary ozone dose by measuring the process yield, in terms of biodegradable dissolved organic carbon (BDOC). Secondly, activated carbon adsorption of the DOC present in ozonated water was quantified. The whole process was tested in a pilot unit under field conditions at the DWTP of Rennes (France). Lab-scale experiments confirmed that ozonation increases the BDOC fraction, reduces the aromaticity of the DOC and produces small size organic compounds. Adsorption tests led to the conclusion that activated carbon unexpectedly removes BDOC first. Finally, the pilot unit results revealed an additional BDOC removal (from 0.10 to 0.15 mg L(-1)) of dissolved organic carbon from the raw water considered. PMID:19906398

  16. Impacts of powdered activated carbon addition on trihalomethane formation reactivity of dissolved organic matter in membrane bioreactor effluent.

    PubMed

    Ma, Defang; Gao, Yue; Gao, Baoyu; Wang, Yan; Yue, Qinyan; Li, Qian

    2014-12-01

    Characteristics and trihalomethane (THM) formation reactivity of dissolved organic matter (DOM) in effluents from two membrane bioreactors (MBRs) with and without powdered activated carbon (PAC) addition (referred to as PAC/MBR and MBR, respectively) were examined to investigate the effects of PAC addition on THM formation of MBR effluent during chlorination. PAC addition increased the specific UV absorbance. Hydrophobic DOM especially hydrophobic acids in PAC/MBR effluent (50%) were more than MBR effluent (42%). DOM with molecular weight <1 kDa constituted 12% of PAC/MBR effluent DOM, which was less than that of MBR effluent (16%). Data obtained from excitation and emission matrix fluorescence spectroscopy revealed that PAC/MBR effluent DOM contained more simple aromatic protein, but had less fulvic acid-like and soluble microbial by-product-like. PAC addition reduced the formation of bromine-containing THMs during chlorination of effluents, but increased THM formation reactivity of effluent DOM. PMID:25150685

  17. COMPARISON OF PROCEDURES TO DETERMINE ADSORPTION CAPACITY OF VOLATILE ORGANIC COMPOUNDS ON ACTIVATED CARBON

    EPA Science Inventory

    Numerous volatile organic compounds (VOCs) are under regulatory consideration for inclusion in the National Primary Drinking Water Standards. Adsorption is a cost-effective treatment technology for control of VOCs. Adsorption capacities were determined for fifteen VOCs in distill...

  18. Activated carbon from biomass

    NASA Astrophysics Data System (ADS)

    Manocha, S.; Manocha, L. M.; Joshi, Parth; Patel, Bhavesh; Dangi, Gaurav; Verma, Narendra

    2013-06-01

    Activated carbon are unique and versatile adsorbents having extended surface area, micro porous structure, universal adsorption effect, high adsorption capacity and high degree of surface reactivity. Activated carbons are synthesized from variety of materials. Most commonly used on a commercial scale are cellulosic based precursors such as peat, coal, lignite wood and coconut shell. Variation occurs in precursors in terms of structure and carbon content. Coir having very low bulk density and porous structure is found to be one of the valuable raw materials for the production of highly porous activated carbon and other important factor is its high carbon content. Exploration of good low cost and non conventional adsorbent may contribute to the sustainability of the environment and offer promising benefits for the commercial purpose in future. Carbonization of biomass was carried out in a horizontal muffle furnace. Both carbonization and activation were performed in inert nitrogen atmosphere in one step to enhance the surface area and to develop interconnecting porosity. The types of biomass as well as the activation conditions determine the properties and the yield of activated carbon. Activated carbon produced from biomass is cost effective as it is easily available as a waste biomass. Activated carbon produced by combination of chemical and physical activation has higher surface area of 2442 m2/gm compared to that produced by physical activation (1365 m2/gm).

  19. Seasonal Dynamics of Soil Labile Organic Carbon and Enzyme Activities in Relation to Vegetation Types in Hangzhou Bay Tidal Flat Wetland

    PubMed Central

    Shao, Xuexin; Yang, Wenying; Wu, Ming

    2015-01-01

    Soil labile organic carbon and soil enzymes play important roles in the carbon cycle of coastal wetlands that have high organic carbon accumulation rates. Soils under three vegetations (Phragmites australis, Spartina alterniflora, and Scirpusm mariqueter) as well as bare mudflat in Hangzhou Bay wetland of China were collected seasonally. Seasonal dynamics and correlations of soil labile organic carbon fractions and soil enzyme activities were analyzed. The results showed that there were significant differences among vegetation types in the contents of soil organic carbon (SOC) and dissolved organic carbon (DOC), excepting for that of microbial biomass carbon (MBC). The P. australis soil was with the highest content of both SOC (7.86 g kg-1) and DOC (306 mg kg-1), while the S. mariqueter soil was with the lowest content of SOC (6.83 g kg-1), and the bare mudflat was with the lowest content of DOC (270 mg kg-1). Soil enzyme activities were significantly different among vegetation types except for urease. The P. australis had the highest annual average activity of alkaline phosphomonoesterase (21.4 mg kg-1 h-1), and the S. alterniflora had the highest annual average activities of β-glycosidase (4.10 mg kg-1 h-1) and invertase (9.81mg g-1 24h-1); however, the bare mudflat had the lowest activities of alkaline phosphomonoesterase (16.2 mg kg-1 h-1), β-glycosidase (2.87 mg kg-1 h-1), and invertase (8.02 mg g-1 24h-1). Analysis also showed that the soil labile organic carbon fractions and soil enzyme activities had distinct seasonal dynamics. In addition, the soil MBC content was significantly correlated with the activities of urease and β-glucosidase. The DOC content was significantly correlated with the activities of urease, alkaline phosphomonoesterase, and invertase. The results indicated that vegetation type is an important factor influencing the spatial-temporal variation of soil enzyme activities and labile organic carbon in coastal wetlands. PMID:26560310

  20. Measurement of Contractile Activity in Small Animal's Digestive Organ by Carbon Nanotube-Based Force Transducer

    NASA Astrophysics Data System (ADS)

    Hirata, Takamichi; Takeda, Naoki; Tsutsui, Chihiro; Koike, Kanako; Shimatani, Yuichi; Sakai, Takafumi; Akiya, Masahiro; Taguchi, Akira

    2011-03-01

    A carbon nanotube (CNT)-based force transducer designed to be embedded in the body of a live animal was fabricated and implanted into the stomach of a rat omit to measure contractile movement. The transducer comprised dispersed poly(ethylene glycol)-grafted multiwalled CNTs applied to a comb-like Au-electrode formed on a poly(dimethylsiloxane) sheet. The implanted rat was injected with acetylcholine to induce muscular contractions and changes in the resistance of the transducer were measured. Such changes arise owing to strain in the CNT network upon distortion. The measured resistance change was found to be proportional to the concentration of injected acetylcholine.

  1. Photocatalytic Oxidation of Volatile Organic Compounds Over Electrospun Activated TIO2/CARBON Nanofiber Composite

    NASA Astrophysics Data System (ADS)

    Gholamvand, Zahra; Aboutalebi, Seyed Hamed; Keyanpour-Rad, Mansoor

    In this study, TiO2/PAN-based fibers were prepared by electrospinning a composite solution containing both the desirable contents of TiO2 and a 10 wt. % PAN polymer solution dissolved in N, N-dimethylformamide. The TiO2 loaded electrospun PAN nanofibers were then carbonized at 1000 °C in N2 atmosphere furnace after stabilization at 230 °C in air. Then CNF/TiO2 nanofibers were oxidized at 450 °C in air. The morphology and structure of the TiO2-embeded carbon nanofibers were investigated by SEM and Raman spectroscopy. Specific surface area was determined using BET equation from N2 adsorption analysis. Photocatalytic tests were conducted in a UV illuminated set-up specialized for the filters using ethanol vapor. The results have shown that ethanol vapor was efficiently degraded on TiO2/CNF composite nanofiber mat under UV illumination. The aim of this study was to further investigate the feasibility of TiO2/ACF for practical indoor air purification.

  2. Efficiency enhancement of solution-processed inverted organic solar cells with a carbon-nanotube-doped active layer

    NASA Astrophysics Data System (ADS)

    Lin, Wen-Kai; Su, Shui-Hsiang; Yeh, Meng-Cheng; Huang, Yang-Chan; Yokoyama, Meiso

    2016-01-01

    Solution-processed titanium-doped ZnO (TZO) is synthesized by the sol-gel method to be the electron-transporting layer (ETL) in an inverted organic solar cell (IOSC). Carbon nanotubes (CNTs) are doped into an active layer of poly(3-hexylthiophene):[6,6]-phenyl C 61 butyric acid methyl ester (P3HT:PCBM). The addition of CNTs in the P3HT:PCBM composite increases the conjugation length of P3HT:PCBM:CNTs, which simultaneously enhances the capacity of the composite to absorb solar energy radiation. Vanadium oxide (V2O5) was spin-coated onto the active layer to be a hole-transporting layer (HTL). The power conversion efficiency (PCE) results indicate that the V2O5 nanobelt structure possesses better phase separation and provides a more efficient surface area for the P3HT:PCBM:CNT active layer to increase photocurrent. The optimized IOSCs exhibited an open circuit voltage (Voc), a short-circuit current density (Jsc), a fill factor (FF), and a PCE of 0.55 V, 6.50 mA/cm2, 58.34%, and 2.20%, respectively, under simulated AM1.5G illumination of 100 mW/cm2.

  3. Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor.

    PubMed

    Racyte, Justina; Langenhoff, Alette A M; Ribeiro, Ana F M M R; Paulitsch-Fuchs, Astrid H; Bruning, Harry; Rijnaarts, Huub H M

    2014-10-01

    Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency electric fields for disinfection. So far, the effects of GAC on bacteria in these fluidized bed reactors are unclear. This paper describes a systematic study of the physico-chemical changes in five microbial media compositions caused by different concentrations (23-350 g/L) of GAC, and the effects of these physico-chemical changes on the metabolic activity and survival of a model microorganism (Escherichia coli YMc10) in a fluidized bed reactor. The chemical adsorption taking place in suspensions with specific GAC changed nutritional, osmotic, and pH conditions in the investigated microbial media (LB, diluted LB, PBS, diluted PBS, and tap water), leading to a decay of the metabolic activity and survival of E. coli. Especially media that are poor in organic and mineral compounds (e.g., PBS) with suspended GAC showed a concentration decay of 3.5 Log CFU/mL E. coli after 6 h. Organic compounds depletion and severe pH variation were enhanced in the presence of higher GAC concentrations. PMID:24729067

  4. Characterization and organic electric-double-layer-capacitor application of KOH activated coal-tar-pitch-based carbons: Effect of carbonization temperature

    NASA Astrophysics Data System (ADS)

    Choi, Poo Reum; Lee, Eunji; Kwon, Soon Hyung; Jung, Ji Chul; Kim, Myung-Soo

    2015-12-01

    The present study reports the influence of pre-carbonization on the properties of KOH-activated coal tar pitch (CTP). The change of crystallinity and pore structure of pre-carbonized CTPs as well as their activated carbons (ACs) as function of pre-carbonization temperature are investigated. The crystallinity of pre-carbonized CTPs increases with increasing the carbonization temperature up to 600 °C, but a disorder occurs during the carbonization around 700 °C and an order happens gradually with increasing the carbonization temperatures in range of 800-1000 °C. The CTPs pre-carbonized at high temperatures are more difficult to be activated with KOH than those pre-carbonized at low temperatures due to the increase of micro-crystalline size and the decrease of surface functional groups. The micro-pores and meso-pores are well developed at around 1.0 nm and 2.4 nm, respectively, as the ACs are pre-carbonized at temperatures of 500-600 °C, exhibiting high specific capacitances as electrode materials for electric double layer capacitor (EDLC). Although the specific surface area (SSA) and pore volume of ACs pre-carbonized at temperatures of 900-1000 °C are extraordinary low (non-porous) as compared to those of AC pre-carbonized at 600 °C, their specific capacitances are comparable to each other. The large specific capacitances with low SSA ACs can be attributed to the structural change resulting from the electrochemical activation during the 1st charge above 2.0 V.

  5. From Bimetallic Metal-Organic Framework to Porous Carbon: High Surface Area and Multicomponent Active Dopants for Excellent Electrocatalysis.

    PubMed

    Chen, Yu-Zhen; Wang, Chengming; Wu, Zhen-Yu; Xiong, Yujie; Xu, Qiang; Yu, Shu-Hong; Jiang, Hai-Long

    2015-09-01

    Bimetallic metal-organic frameworks are rationally synthesized as templates and employed for porous carbons with retained morphology, high graphitization degree, hierarchical porosity, high surface area, CoNx moiety and uniform N/Co dopant by pyrolysis. The optimized carbon with additional phosphorus dopant exhibits excellent electrocatalytic performance for the oxygen reduction reaction, which is much better than the benchmark Pt/C in alkaline media. PMID:26193083

  6. [Effect of physico-chemical characteristics of activated carbon on the adsorption of organic pollutants in natural water].

    PubMed

    Zhang, Jing-Yi; Shi, Bao-You; Xie, Jian-Kun; Yuan, Hong-Lin; Wang, Dong-Sheng

    2011-02-01

    In this paper, the adsorption characteristics of two synthetic organic compounds (SOCs), i. e., methyl parathion(MP) and trichloroethylene (TCE), and natural organic matter (NOM) on powdered activated carbons (PAC) in natural water were studied. On the basis of fully characterizing the physical and chemical characteristics of PAC, the effect of physical and chemical properties of PAC on the adsorption of low molecular weight SOCs in natural water was studied by correlation analysis. The effect of molecular weight fractionation on the adsorption of NOM on PAC was investigated using high performance size exclusion chromatography (HPSEC). It was found that, compared to the surface chemistry, the physical property (pore properties) of PAC was the critical factor to determine its adsorption capacity of MP and TCE in natural water. The adsorption of the low molecular weight SOC and NOM with apparent molecular weight (AMW) < 500 on PAC was primarily impacted by the micropore surface area, and that of NOM with 500 < AMW < 3 000 was affected by the mesopore surface area combined with the mesopore size distribution. PMID:21528573

  7. Activated carbons impregnated with iron oxide nanoparticles for enhanced removal of bisphenol A and natural organic matter.

    PubMed

    Park, Hak-Soon; Koduru, Janardhan Reddy; Choo, Kwang-Ho; Lee, Byungwhan

    2015-04-01

    The removal of bisphenol A (BPA) is important for the provision of safe drinking water, but its removal in the presence of natural organic matter (NOM) is challenging. Thus, the present study involved the fabrication and characterization of powdered activated carbons impregnated with iron oxide nanoparticles (IONPACs) with respect to the simultaneous removal of BPA and NOM. The number of Fe ions loaded into the PAC pores was optimized in terms of exposure time. Impregnation with iron oxide reduced the surface area and pore volume, but the pore size was maintained. IONPAC adsorbents had considerably greater sorption capabilities for BPA and NOM compared to native, bare PAC particles. The adsorption capacities of BPA and NOM were in the following sequence: bare PACorganics (e.g., phenolic/carboxyl groups). Iron oxide impregnation enabled the BPA uptake to be maintained in the presence of NOM, indicating that the hybrid adsorbent provided synergistic adsorption characteristics for BPA and NOM. Although the solution pH had a negligible impact on BPA uptake, the ionic strength showed a significant effect, particularly in the presence of divalent Ca ions. PMID:25594935

  8. Chromophoric dissolved organic matter and microbial enzymatic activity. A biophysical approach to understand the marine carbon cycle.

    PubMed

    Gonnelli, Margherita; Vestri, Stefano; Santinelli, Chiara

    2013-12-01

    This study reports the first information on extracellular enzymatic activity (EEA) combined with a study of DOM dynamics at the Arno River mouth. DOM dynamics was investigated from both a quantitative (dissolved organic carbon, DOC) and a qualitative (absorption and fluorescence of chromophoric DOM, CDOM) perspective. The data here reported highlight that the Arno River was an important source of both DOC and CDOM for this coastal area. CDOM optical properties suggested that terrestrial DOM did not undergo simple dilution at the river mouth but, other physical-chemical and biological processes were probably at work to change its molecular characteristics. This observation was further supported by the "potential" enzymatic activity of β-glucosidase (BG) and leucine aminopeptidase (LAP). Their Vmax values were markedly higher in the river water than in the seawater and their ratio suggested that most of the DOM used by microbes in the Arno River was polysaccharide-like, while in the seawater it was mainly protein-like. PMID:23850176

  9. Removal of Volatile Organic Contaminants (VOCs) from the Groundwater Sources of Drinking Water via Granular Activated Carbon Treatment (WaterRF Report 4440)

    EPA Science Inventory

    The overall goal of this project was to assess the feasibility of granular activated carbon (GAC) for the treatment of selected carcinogenic volatile organic compounds (cVOC) to sub-μg/L levels. The project consisted of three tasks. The task objectives are: Task I - determine c...

  10. Changes in Labile Organic Carbon Fractions and Soil Enzyme Activities after Marshland Reclamation and Restoration in the Sanjiang Plain in Northeast China

    NASA Astrophysics Data System (ADS)

    Song, Yanyu; Song, Changchun; Yang, Guisheng; Miao, Yuqing; Wang, Jiaoyue; Guo, Yuedong

    2012-09-01

    The extensive reclamation of marshland into cropland has tremendously impacted the ecological environment of the Sanjiang Plain in northeast China. To understand the impacts of marshland reclamation and restoration on soil properties, we investigated the labile organic carbon fractions and the soil enzyme activities in an undisturbed marshland, a cultivated marshland and three marshlands that had been restored for 3, 6 and 12 years. Soil samples collected from the different management systems at a depth of 0-20 cm in July 2009 were analyzed for soil organic carbon (SOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) and easily degradable organic carbon. In addition, the activities of the invertase, β-glucosidase, urease and acid phosphatase were determined. These enzymes are involved in C, N and P cycling, respectively. Long-term cultivation resulted in decreased SOC, DOC, MBC, microbial quotient and C (invertase, β-glucosidase) and N-transforming (urease) enzyme activities compared with undisturbed marshland. After marshland restoration, the MBC and DOC concentrations and the soil invertase, β-glucosidase and urease activities increased. Soil DOC and MBC concentrations are probably the main factors responsible for the different invertase, β-glucosidase and urease activities. In addition, marshland restoration caused a significant increase in the microbial quotient, which reflects enhanced efficiency of organic substrate use by microbial biomass. Our observations demonstrated that soil quality recovered following marshland restoration. DOC, MBC and invertase, β-glucosidase and urease activities were sensitive for discriminating soil ecosystems under the different types of land use. Thus, these parameters should be considered to be indicators for detecting changes in soil quality and environmental impacts in marshlands.

  11. Changes in labile organic carbon fractions and soil enzyme activities after marshland reclamation and restoration in the Sanjiang Plain in northeast China.

    PubMed

    Song, Yanyu; Song, Changchun; Yang, Guisheng; Miao, Yuqing; Wang, Jiaoyue; Guo, Yuedong

    2012-09-01

    The extensive reclamation of marshland into cropland has tremendously impacted the ecological environment of the Sanjiang Plain in northeast China. To understand the impacts of marshland reclamation and restoration on soil properties, we investigated the labile organic carbon fractions and the soil enzyme activities in an undisturbed marshland, a cultivated marshland and three marshlands that had been restored for 3, 6 and 12 years. Soil samples collected from the different management systems at a depth of 0-20 cm in July 2009 were analyzed for soil organic carbon (SOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) and easily degradable organic carbon. In addition, the activities of the invertase, β-glucosidase, urease and acid phosphatase were determined. These enzymes are involved in C, N and P cycling, respectively. Long-term cultivation resulted in decreased SOC, DOC, MBC, microbial quotient and C (invertase, β-glucosidase) and N-transforming (urease) enzyme activities compared with undisturbed marshland. After marshland restoration, the MBC and DOC concentrations and the soil invertase, β-glucosidase and urease activities increased. Soil DOC and MBC concentrations are probably the main factors responsible for the different invertase, β-glucosidase and urease activities. In addition, marshland restoration caused a significant increase in the microbial quotient, which reflects enhanced efficiency of organic substrate use by microbial biomass. Our observations demonstrated that soil quality recovered following marshland restoration. DOC, MBC and invertase, β-glucosidase and urease activities were sensitive for discriminating soil ecosystems under the different types of land use. Thus, these parameters should be considered to be indicators for detecting changes in soil quality and environmental impacts in marshlands. PMID:22744158

  12. Activated carbon material

    DOEpatents

    Evans, A. Gary

    1978-01-01

    Activated carbon particles for use as iodine trapping material are impregnated with a mixture of selected iodine and potassium compounds to improve the iodine retention properties of the carbon. The I/K ratio is maintained at less than about 1 and the pH is maintained at above about 8.0. The iodine retention of activated carbon previously treated with or coimpregnated with triethylenediamine can also be improved by this technique. Suitable flame retardants can be added to raise the ignition temperature of the carbon to acceptable standards.

  13. Granular activated carbon for simultaneous adsorption and biodegradation of toxic oil sands process-affected water organic compounds.

    PubMed

    Islam, Md Shahinoor; Zhang, Yanyan; McPhedran, Kerry N; Liu, Yang; Gamal El-Din, Mohamed

    2015-04-01

    Naphthenic acids (NAs) released into oil sands process-affected water (OSPW) during bitumen processing in Northern Alberta are problematic for oil sands industries due to their toxicity in the environment and resistance to degradation during conventional wastewater treatment processes. Granular activated carbon (GAC) has shown to be an effective media in removing biopersistent organics from wastewater using a combination of adsorption and biodegradation removal mechanisms. A simultaneous GAC (0.4 g GAC/L) adsorption and biodegradation (combined treatment) study was used for the treatment of raw and ozonated OSPW. After 28 days of batch treatment, classical and oxidized NAs removals for raw OSPW were 93.3% and 73.7%, and for ozonated OSPW were 96.2% and 77.1%, respectively. Synergetic effects of the combined treatment process were observed in removals of COD, the acid extractable fraction, and oxidized NAs, which indicated enhanced biodegradation and bioregeneration in GAC biofilms. A bacteria copy number >10(8) copies/g GAC on GAC surfaces was found using quantitative real time polymerase chain reaction after treatment for both raw and ozonated OSPW. A Microtox(®) acute toxicity test (Vibrio fischeri) showed effective toxicity removal (>95.3%) for the combined treatments. Therefore, the simultaneous GAC adsorption and biodegradation treatment process is a promising technology for the elimination of toxic OSPW NAs. PMID:25617868

  14. Lab-testing, predicting, and modeling multi-stage activated carbon adsorption of organic micro-pollutants from treated wastewater.

    PubMed

    Zietzschmann, F; Altmann, J; Hannemann, C; Jekel, M

    2015-10-15

    Multi-stage reuse of powdered activated carbon (PAC) is often applied in practice for a more efficient exploitation of the PAC capacity to remove organic micro-pollutants (OMP). However, the adsorption mechanisms in multi-stage PAC reuse are rarely investigated, as large-scale experiments do not allow for systematic tests. In this study, a laboratory method for the separation of PAC/water suspensions and the subsequent reuse of the PAC and the water was developed. The method was tested on wastewater treatment plant (WWTP) effluent in a setup with up to 7 PAC reuse stages. The tests show that the overall OMP removal from WWTP effluent can be increased when reusing PAC. The reason is that a repeated adsorption in multi-stage PAC reuse results in similar equilibrium concentrations as a single-stage adsorption. Thus, a single relationship between solid and liquid phase OMP concentrations appears valid throughout all stages. This also means that the adsorption efficiency of multi-stage PAC reuse setups can be estimated from the data of a single-stage setup. Furthermore, the overall OMP removals in multi-stage setups coincide with the overall UV254 removals, and for each respective OMP one relationship to UV254 removal is valid throughout all stages. The results were modeled by a simple modification of the equivalent background compound model (EBCM) which was also used to simulate the additional OMP removals in multi-stage setups with up to 50 reuse stages. PMID:26117373

  15. Developing Polycation-Clay Sorbents for Efficient Filtration of Diclofenac: Effect of Dissolved Organic Matter and Comparison to Activated Carbon.

    PubMed

    Kohay, Hagay; Izbitski, Avital; Mishael, Yael G

    2015-08-01

    The presence of nanoconcentrations of persistent pharmaceuticals in treated wastewater effluent and in surface water has been frequently reported. A novel organic-inorganic hybrid sorbent based on adsorbing quarternized poly vinylpyridinium-co-styrene (QPVPcS) to montmorillonite (MMT) was designed for the removal of the anionic micropollutants. QPVPcS-clay composites were characterized by X-ray diffraction, FTIR, thermal gravimetric analysis, Zeta potential and element analysis. Based on these measurements polymer-clay micro- and nanostructures, as a function of polymer loading, were suggested. The affinity of the anionic pharmaceutical, diclofenac (DCF), to the composite was high and did not decrease dramatically with an increase of ionic strength, indicating that the interactions are not only electrostatic. The presence of humic acid (HA) did not hinder DCF removal by the composite; whereas, its filtration by granulated activated carbon (GAC) was compromised in the presence of HA. The kinetics and adsorption at equilibrium of DCF to the composite and to GAC were measured and modeled by the time dependent Langmuir equation. The adsorption of DCF to the composite was significantly faster than to GAC. Accordingly, the filtration of micro- and nanoconcentrations of DCF by composite columns, in the presence of HA, was more efficient than by GAC columns. PMID:26126078

  16. The effects of mediator and granular activated carbon addition on degradation of trace organic contaminants by an enzymatic membrane reactor.

    PubMed

    Nguyen, Luong N; Hai, Faisal I; Price, William E; Leusch, Frederic D L; Roddick, Felicity; Ngo, Hao H; Guo, Wenshan; Magram, Saleh F; Nghiem, Long D

    2014-09-01

    The removal of four recalcitrant trace organic contaminants (TrOCs), namely carbamazepine, diclofenac, sulfamethoxazole and atrazine by laccase in an enzymatic membrane reactor (EMR) was studied. Laccases are not effective for degrading non-phenolic compounds; nevertheless, 22-55% removal of these four TrOCs was achieved by the laccase EMR. Addition of the redox-mediator syringaldehyde (SA) to the EMR resulted in a notable dose-dependent improvement (15-45%) of TrOC removal affected by inherent TrOC properties and loading rates. However, SA addition resulted in a concomitant increase in the toxicity of the treated effluent. A further 14-25% improvement in aqueous phase removal of the TrOCs was consistently observed following a one-off dosing of 3g/L granular activated carbon (GAC). Mass balance analysis reveals that this improvement was not due solely to adsorption but also enhanced biodegradation. GAC addition also reduced membrane fouling and the SA-induced toxicity of the effluent. PMID:24980029

  17. EFFECTS OF COVAPORS ON ADSORPTION RATE COEFFICIENTS OF ORGANIC VAPORS ADSORBED ONTO ACTIVATED CARBON FROM FLOWING AIR

    SciTech Connect

    G. WOOD

    2000-12-01

    Published breakthrough time, adsorption rate, and capacity data for components of organic vapor mixtures adsorbed from flows through fixed activated carbon beds have been analyzed. Capacities (as stoichiometric centers of constant pattern breakthrough curves) yielded stoichiometric times {tau}, which are useful for determining elution orders of mixture components. We also calculated adsorption rate coefficients k{sub v} of the Wheeler (or, more general Reaction Kinetic) breakthrough curve equation, when not reported, from breakthrough times and {tau}. Ninety-five k{sub v} (in mixture)/ k{sub v} (single vapor) ratios at similar vapor concentrations were calculated and averaged for elution order categories. For 43 first-eluting vapors the average ratio (1.07) was statistically no different (0.21 standard deviation) than unity, so that we recommend using the single-vapor k{sub v} for such. Forty-seven second-eluting vapor ratios averaged 0.85 (0.24 standard deviation), also not significantly different from unity; however, other evidence and considerations lead us recommend using k{sub v} (in mixture) = 0.85 k{sub v} (single vapor). Five third- and fourth-eluting vapors gave an average of 0.56 (0.16 standard deviation) for a recommended k{sub v} (in mixture) = 0.56 k{sub v} (single vapor) for such.

  18. Impacts of coagulation on the adsorption of organic micropollutants onto powdered activated carbon in treated domestic wastewater.

    PubMed

    Altmann, Johannes; Zietzschmann, Frederik; Geiling, Eva-Linde; Ruhl, Aki Sebastian; Sperlich, Alexander; Jekel, Martin

    2015-04-01

    The application of powdered activated carbon (PAC) as an advanced wastewater treatment step for the removal of organic micropollutants (OMP) necessitates complete separation of the PAC particles, e.g. by coagulation. In this study, potential positive or negative indirect or direct effects of coagulation on the adsorption of OMPs onto PAC in treated wastewater were investigated. Although the concentration of dissolved organic matter (DOM) was significantly reduced by coagulation, the selective removal of mainly larger DOM components such as biopolymers and humic substances did not improve subsequent OMP adsorption onto PAC, demonstrating that coagulation has minor effects on DOM constituents that are relevant for direct competition or pore blocking. The combination of coagulation and adsorption yielded the sum of the individual removals, as adsorption predominantly affected smaller compounds. While the formation of flocs led to visible incorporation of PAC particles, no significant mass transfer limitations impeded the OMP adsorption. As a result, the dosing sequence of coagulant and PAC is not critical for efficient adsorption of OMPs onto PAC. The relationships between adsorptive OMP removal and corresponding reduction of UV absorption at 254 nm (UVA254) as a promising surrogate correlation for the real-time monitoring and PAC adjustment were affected by coagulation, leading to individual correlations depending on the water composition. Correcting for UVA254 reduction by coagulation produces adsorptive UVA254 removal, which correlates highly with OMP removal for different WWTP effluents and varying coagulant doses and can be applied in combined adsorption/coagulation processes to predict OMP removal and control PAC dosing. PMID:25582393

  19. Effect of the permafrost thawing on the organic carbon and microbial activity in thermokarst lakes of Western Siberia: important source of carbon dioxide in the atmosphere

    NASA Astrophysics Data System (ADS)

    Shirokova, L. S.; Pokrovsky, O. S.; Kirpotin, S. N.; Dupre, B.

    2008-12-01

    Ongoing processes of the permafrost thawing in Western Siberia are likely to increase the surface of water reservoirs via forming so-called thermokarst lakes, mobilizing the organic carbon (OC) from the soil pool to the rivers and, finally, to the ocean, and thus modifying the fluxes of methane and CO2 to the atmosphere. In order to understand the mechanisms of carbon mobilization and biodegradation during permafrost thawing and to establish the link between the OC and microbial activity in forming thermokarstic lakes, we performed a comparative multidisciplinary study on the biogeochemistry of OC and metals in lakes located in the northern part of Western Siberia. About 10 lakes and small ponds of various size and age were sampled for dissolved and colloidal organic carbon and metals and total bacterial cell number. There is a systematic evolution of DOC, pH, trace elements and biological activity during successions of thermokarst lakes encountered in the present study. At the beginning of permafrost thawing at the scale of several meter size ponds, fast lixiviation of unaltered peat yields significant amount of OC, major and trace elements; the pH of these waters is between 3.5 and 4.0 and the conductivity is 20-30 μS. The intermediate stage of lake formation still preserve low pHs, high DOC and conductivity, even in relatively large, up to 1 km diameter but fast growing lakes. At these stages, there is no any productivity as phytoplankton cannot live in these acidic waters and bacterial mineralization intensity is around 0.3 mg C/L/day both in the surface and bottom horizons. Once the lake border is stabilized, there are no new "unaltered peat" sources and the biological processes start to consume the OC and nutrients. At this stage, there is still no production in the water column (< 0.01 mg C/L/day) but the bacterial mineralization intensity remains high, up to 0.3 mg C/L/day. At this final stage, the remaining part of the lake located in the centre of the

  20. TRACE ORGANICS VARIATION ACROSS THE WASTEWATER TREATMENT SYSTEM OF A CLASS-B REFINERY AND ESTIMATE OF REMOVAL OF REFRACTORY ORGANICS BY ADD-ON MIXED-MEDIA FILTRATION AND GRANULAR ACTIVATED CARBON AT PILOT SCALE

    EPA Science Inventory

    This report presents the results of research to evaluate the efficiency of pilot-scale granular activated carbon for the removal of organic compounds refractory to the activated-sludge treatment system of a Class B petroleum refinery that met BPT ('best practicable technology') i...

  1. CARBON ADSORPTION ISOTHERMS FOR TOXIC ORGANICS

    EPA Science Inventory

    An experimental protocol for measuring the activated carbon adsorption isotherm was developed and applied to a wide range of organic compounds. Methods for treatment of the isotherm data and a standard format for presentation of results are shown. In the early phase of the study ...

  2. Characteristics of maize biochar with different pyrolysis temperatures and its effects on organic carbon, nitrogen and enzymatic activities after addition to fluvo-aquic soil.

    PubMed

    Wang, Xiubin; Zhou, Wei; Liang, Guoqing; Song, Dali; Zhang, Xiaoya

    2015-12-15

    In this study, the characteristics of maize biochar produced at different pyrolysis temperatures (300, 450 and 600°C) and its effects on organic carbon, nitrogen and enzymatic activities after addition to fluvo-aquic soil were investigated. As pyrolysis temperature increased, ash content, pH, electrical conductivity, surface area, pore volume and aromatic carbon content of biochar increased while yield, ratios of oxygen:carbon and hydrogen: carbon and alkyl carbon content decreased. During incubation, SOC, total N, and ammonium-N contents increased in all biochar-amended treatments compared with the urea treatment; however, soil nitrate-N content first increased and then decreased with increasing pyrolysis temperature of the applied biochar. Extracellular enzyme activities associated with carbon transformation first increased and then decreased with biochars pyrolyzed at 450 and 600°C. Protease activity markedly increased with increased pyrolysis temperatures, whereas pyrolysis temperature had limited effect on soil urease activity. The results indicated that the responses of extracellular enzymes to biochar were dependent on the pyrolysis temperature, the enzyme itself and incubation time as well. PMID:26298256

  3. PREDICTING THE ADSORPTION CAPACITY OF ACTIVATED CARBON FOR EMERGING ORGANIC CONTAMINANTS FROM FUNDAMENTAL ADSORBENT AND ADSORBATE PROPERTIES - PRESENTATION

    EPA Science Inventory

    A quantitative structure-property relationship (QSPR) was developed and combined with the Polanyi-Dubinin-Manes model to predict adsorption isotherms of emerging contaminants on activated carbons with a wide range of physico-chemical properties. Affinity coefficients (βl

  4. QUANTITATIVE STRUCTURE—PROPERTY RELATIONSHIPS FOR ENHANCING PREDICTIONS OF SYNTHETIC ORGANIC CHEMICAL REMOVAL FROM DRINKING WATER BY GRANULAR ACTIVATED CARBON

    EPA Science Inventory


    A number of mathematical models have been developed to predict activated carbon column performance using single-solute isotherm data as inputs. Many assumptions are built into these models to account for kinetics of adsorption and competition for adsorption sites. This work...

  5. EFFECT OF MOLECULAR OXYGEN ON THE ACTIVATED CARBON ADSORPTION OF NATURAL ORGANIC MATTER IN OHIO RIVER WATER

    EPA Science Inventory

    Recently published data show that the adsorptive capacity of granular activated carbon for phenois increases significantly in the presence of molecular oxygen (Vidic, Suidan,Traegner and Nakhla, 1990). in this study, the effect of molecular oxygen on the adsorptive capacity of a...

  6. COMBINED USE OF ION EXCHANGE RESINS AND GRANULAR ACTIVATED CARBON FOR THE CONTROL OF ORGANIC MATTER AND DISINFECTION BY PRODUCTS

    EPA Science Inventory

    The use of anion exchange resin as a pretreatment step to granular activated carbon is evaluated. erformance is evaluated by DOC, SAC, TOXFP, and THMFP parameters. hio River water and Palm Beach groundwater are used. he results show that resin pretreatment is significant in exten...

  7. Emission of short chained organic acids, aldehydes and monoterpenes from Quercus ilex L. and Pinus pinea L. in relation to physiological activities, carbon budget and emission algorithms

    NASA Astrophysics Data System (ADS)

    Kesselmeier, J.; Bode, K.; Hofmann, U.; Müller, H.; Schäfer, L.; Wolf, A.; Ciccioli, P.; Brancaleoni, E.; Cecinato, A.; Frattoni, M.; Foster, P.; Ferrari, C.; Jacob, V.; Fugit, J. L.; Dutaur, L.; Simon, V.; Torres, L.

    We report on the emission of monoterpenes, short-chained organic acids and aldehydes from Mediterranean oak ( Quercus ilex L.) and pine (Pinus pinea L.). All studies were done with dynamic cuvettes enclosing intact branches at the top of the canopy flushed with ambient air. Daily trends are compared with the photosynthetic active radiation (PAR), leaf temperature and the physiological activities of the enclosed branches, i.e. assimilation and transpiration, with special attention on the carbon budget. Oak emits monoterpenes in high amounts, up to 2% of the assimilated carbon. As compared with monoterpenes, short-chained organic acids and aldehydes are of minor importance for oak. However, on a leaf dry-weight basis equal amounts of acids and aldehydes are released from oak and pine. As pine emitted only low amounts of terpenes (below 0.2% of the assimilated carbon) the release of terpenes and oxygenated compounds is of equal importance for this species. A comparison of a modelled light and temperature driven emission with the observed volatile organic compounds (VOC) emissions showed good agreement for monoterpenes as well as for organic acids emitted in the case of oak. For pine only the release of acids showed an adequate relation to the algorithm data, whereas the terpene emissions seemed to be dominated by temperature effects.

  8. Soil Enzyme Activities, Microbial Communities and Carbon and Nitrogen Availability in Organic Agroecosystems Across an Intensively-Managed Agricultural Landscape

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Variability in the activity and composition of soil microbial communities may have important implications for the suite of microbially-derived ecosystem functions upon which agricultural systems rely, particularly organic agriculture. An on-farm approach was used to investigate microbial communitie...

  9. Microorganisms, Organic Carbon, and Their Relationship with Oxidant Activity in Hyper-Arid Mars-Like Soils: Implications for Soil Habitability

    NASA Technical Reports Server (NTRS)

    Valdivia-Silva, Julio E.; Karouia, Fathi; Navarro-Gonzalez, Rafael; McKay, Christopher

    2016-01-01

    Soil samples from the hyper-arid region in the Atacama 23 Desert in Southern Peru (La Joya Desert) were analyzed for total and labile organic carbon (TOC & LOC), phospholipid fatty acids analysis (PLFA), quantitative real time polymerase chain reaction (qRT-PCR), 4',6- diamidino-2-phenylindole (DAPI)-fluorescent microscopy, culturable microorganisms, and oxidant activity, in order to understand the relationship between the presence of organic matter and microorganisms in these types of soils. TOC content levels were similar to the labile pool of carbon suggesting the absence of recalcitrant carbon in these soils. The range of LOC was from 2 to 60 micro-g/g of soil. PLFA analysis indicated a maximum of 2.3 x 10(exp 5) cell equivalents/g. Culturing of soil extracts yielded 1.1 x 10(exp 2)-3.7 x 10(exp 3) CFU/g. qRT-PCR showed between 1.0 x 10(exp 2) and 8 x 10(exp 3) cells/g; and DAPI fluorescent staining indicated bacteria counts up to 5 x 104 cells/g. Arid and semiarid samples (controls) showed values between 10(exp 7) and 10(exp 11) cells/g with all of the methods used. Importantly, the concentration of microorganisms in hyper-arid soils did not show any correlation with the organic carbon content; however, there was a significant dependence on the oxidant activity present in these soil samples evaluated as the capacity to decompose sodium formate in 10 hours. We suggest that the analysis of oxidant activity could be a useful indicator of the microbial habitability in hyper-arid soils, obviating the need to measure water activity over time. This approach could be useful in astrobiological studies on other worlds.

  10. Optimizing the industrial wastewater pretreatment by activated carbon and coagulation: effects of hydrophobicity/hydrophilicity and molecular weights of dissolved organics.

    PubMed

    Khan, M Hammad; Ha, Dong-Hwan; Jung, Jinyoung

    2013-01-01

    This study addresses industrial wastewater treatment to remove dissolved organic compounds (DOC) using Fenton and coagulation processes, followed by granular activated carbon (GAC), and powdered activated carbon (PAC) as a pretreatment before reverse osmosis (RO). The effects of the hydrophobic / hydrophilic fractions and the molecular weights (MW) of the organics on DOC removal were tested and used to optimize the combination process. The raw wastewater (RWW) had a dominant hydrophobic fraction, as determined by polymeric resins Amberlite XAD-4. High performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) results showed that MW of organics were 256, 172, 258, 146, 392, 321, 182, 373, 276, 365, 409 and 453 in increasing order of hydrophobicity. GAC had higher adsorption capacity and was more selective for hydrophobic DOC removal than PAC. The removal efficiency of DOC by PAC and GAC was decreased after Fenton treatment, which decreased the hydrophobic fraction. Coagulation with ferric chloride efficiently removed the non-ionic hydrophilic and anionic hydrophilic organics. The coagulant doses selected as a pretreatment before GAC were 2.1 and 15.5 mg Fe(III)/mg DOC. The effluent total organic carbon (TOC) trends were correlated with the hydrophobic and hydrophilic fractions by using a rapid small-scale column test (RSSCT) for GAC breakthrough with a scale down factor of 5. GAC preferentially adsorbed the hydrophobic and the cationic hydrophilic organics. The effluent TOC trend could be divided into four stages: maximum adsorption, hydrophobic stage, exhaustion, and biological. The TOC removal after the exhaustion stage was almost equal to the hydrophilic fraction of TOC. Therefore these results demonstrated that the combination of coagulation and GAC adsorption was a highly efficient process for reducing DOC. PMID:23383639

  11. Subduction of Organic Carbon into the Earth

    NASA Astrophysics Data System (ADS)

    Plank, T. A.; Malinverno, A.

    2015-12-01

    Seafloor sediments approach active subduction zones with small amounts (generally < 1 dry weight %) of organic carbon, but this small concentration nonetheless constitutes a significant flux over geological time with respect to the size, isotopic composition and electron balance of the carbosphere. In order to quantify the flux of organic carbon into subduction zones, we have examined carbon concentration and density measurements provided by successive drilling programs (DSDP, ODP, IODP) for cores that sample complete sediment sections to basement near deep sea trenches. An interpolation scheme compensates for sparse or non-uniform analyses, and a weighted bulk concentration is calculated for organic carbon (OC) and inorganic carbonate (IC) for each site. When multiplied by the sediment thickness, the trench length and the convergence velocity, a subducted mass flux can be obtained. Sites with the greatest concentration of OC include those that pass beneath regions of high biological productivity (such as the Eastern Equatorial Pacific) and those that receive terrigenous turbidites (e.g., Indus and Begal Fans, Gulf of Alaska, Cascadia, etc). Together, terrigenous turbidites make up about 60% of the global subducted sediment (GLOSS), and thus have a strong control on the concentration of OC in GLOSS. Sites dominated by terrigenous turbidites have 0.4 wt% OC on average (1sd = 0.1 wt%), and GLOSS is very similar, yielding about 6 MtC/yr OC subducted globally. This flux is enough to subduct the entire surface pool of OC every 2.6 Ga, which if not returned, or returned in a more oxidized form, could contribute to a significant rise in oxygen at the surface of the Earth. Seemingly fortuitously, the OC/total carbon fraction in GLOSS is 20%, very near the long term average required to maintain the isotopic composition of marine carbonates at ~ 0 per mil d13C over much of Earth history.

  12. Colloidal activated carbon for in-situ groundwater remediation--Transport characteristics and adsorption of organic compounds in water-saturated sediment columns.

    PubMed

    Georgi, Anett; Schierz, Ariette; Mackenzie, Katrin; Kopinke, Frank-Dieter

    2015-08-01

    Colloidal activated carbon can be considered as a versatile adsorbent and carrier material for in-situ groundwater remediation. In analogy to other nanoremediation approaches, activated carbon colloids (ACC) can be injected into the subsurface as aqueous suspensions. Deposition of ACC on the sediment creates a sorption barrier against further spreading of hydrophobic pollutants. This study deals with the optimization of ACC and their suspensions with a focus on suspension stability, ACC mobility in saturated porous media and sorption efficiency towards organic contaminants. ACC with an appropriate particle size range (d50=0.8μm) were obtained from a commercial powdered activated carbon product by means of wet-grinding. Among the various methods tested for stabilization of ACC suspensions, addition of humic acid (HA) and carboxymethyl cellulose (CMC) showed the best results. Due to electrosteric stabilization by adsorption of CMC, suspensions remained stable even at high ACC concentrations (11gL(-1)) and conditions typical of very hard water (5mM divalent cations). Furthermore, CMC-stabilized ACC showed high mobility in a water-saturated sandy sediment column (filter coefficient λ=0.2m(-1)). Such mobility is a pre-requisite for in-situ installation of sorption or reaction barriers by simple injection-well or direct-push application of ACC suspensions. Column experiments with organic model compounds proved the efficacy of ACC deposits on sediment for contaminant adsorption and retardation under flow-through conditions. PMID:26070009

  13. Self-assembly of cobalt-centered metal organic framework and multiwalled carbon nanotubes hybrids as a highly active and corrosion-resistant bifunctional oxygen catalyst

    NASA Astrophysics Data System (ADS)

    Fang, Yiyun; Li, Xinzhe; Li, Feng; Lin, Xiaoqing; Tian, Min; Long, Xuefeng; An, Xingcai; Fu, Yan; Jin, Jun; Ma, Jiantai

    2016-09-01

    Metal organic frameworks (MOF) derived carbonaceous materials have emerged as promising bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts for electrochemical energy conversion and storage. But previous attempts to overcome the poor electrical conductivity of MOFs hybrids involve a harsh high-template pyrolytic process to in situ form carbon, which suffer from extremely complex operation and inevitable carbon corrosion at high positive potentials when OER is operated. Herein, a self-assembly approach is presented to synthesize a non-precious metal-based, high active and strong durable Co-MOF@CNTs bifunctional catalyst for OER and ORR. CNTs not only improve the transportation of the electrons but also can sustain the harsh oxidative environment of OER without carbon corrosion. Meanwhile, the unique 3D hierarchical structure offers a large surface area and stable anchoring sites for active centers and CNTs, which enables the superior durability of hybrid. Moreover, a synergistic catalysis of Co(II), organic ligands and CNTs will enhance the bifunctional electrocatalytic performance. Impressively, the hybrid exhibits comparable OER and ORR catalytic activity to RuO2 and 20 wt% Pt/C catalysts and superior stability. This facile and versatile strategy to fabricating MOF-based hybrids may be extended to other electrode materials for fuel cell and water splitting applications.

  14. Air stripping, oxidation, and activated-carbon adsorption studies for removal of taste and odor organics from water

    SciTech Connect

    Lalezary-Craig, S.

    1987-01-01

    A major class of water-consumer complaints are attributed to naturally occurring causatives of tastes and odors, among which a subgroup - the earthy-musty taste and odor compounds, documented to be spread worldwide - provides a special challenge to the scientific community and water utilities. The study was designed and executed to develop a firm basis for an understanding of the problem, as well as for optimization of process parameters for different-treatment techniques. The investigation began with determination of the physicochemical properties of a group of five earthy-musty taste and odor compounds including geosmin, 2-isobutyl-3-methoxy pyrazine (IBMP), 2-isopropyl-3-methoxy pyrazine (IPMP), 2-methylisoborneol (MIB), and 2, 3, 6-trichloroanisole (TCA). The second phase of the study investigated aeration, the application of oxidants such as chlorine, chlorine dioxide, and potassium permanganate, and several absorbents including manganese dioxide, kaolinite, and bentonite, for the mitigation of taste-and-odor problem. Other treatment processes investigated were ozonation and activated carbon adsorption. To investigate the efficiency of powdered activated carbon and closely simulate full-scale treatment operations, pilot-plant studies were conducted at one of the several plants operated by the Metropolitan Water District of Southern California.

  15. Seasonal variation in soil organic carbon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic carbon in soil is most often measured at a single point in time, under the assumption that the major pools of organic carbon change so slowly that variation over weeks or months will be insignificant. The validity of this assumption has implications for accurate comparison of soil carbon bet...

  16. Radiocarbon Evidence for Active Turnover of Pore-Water Dissolved Organic Carbon in the Methanogenic and Sulfate-Methane-Transition Zones of Santa Barbara Basin Sediments

    NASA Astrophysics Data System (ADS)

    Komada, T.; Li, H. L.; Cada, A. K.; Burdige, D.; Magen, C.; Chanton, J.; Grose, A. M.

    2014-12-01

    Diverse metabolic activities have been documented in the deep biosphere. However, how these activities affect carbon cycling in the subsurface, and how they in turn affect the marine and global cycles of carbon are still unclear. Here we present natural-abundance 14C and 13C data from the uppermost 4.5 m of the sediments of the Santa Barbara Basin, California Borderland, showing active turnover of dissolved organic carbon (DOC) within, and immediately below, the sulfate-methane transition zone (SMTZ; ~1.25 m). DOC concentrations increased with depth throughout the core, indicating net production within the sediment column. Enhanced DOC production was observed near the sediment-water interface, and also at ~30 cm below the SMTZ (~1.55 m). ∆14C values of DOC increased across the sediment-water interface, then decreased with depth, consistent with net production of modern DOC near the sediment-water interface, and input of 14C-depleted DOC from deeper horizons. An isotope mixing plot constructed with these data shows that the DOC diffusing upward at the base of the core is devoid of 14C, yet the DOC diffusing into and out of the SMTZ is relatively enriched (-460‰ and -300‰, respectively). This difference in 14C content of the DOC flux can only be reconciled if the following two are occurring within, and immediately below, the SMTZ: (1) >90% of the 14C-dead basal DOC flux is removed from the pore water (by, e.g., oxidation, fermentation, methanogenesis, precipitation), and (2) this DOC is replaced by material produced in this region at a rate that exceeds the upward basal flux. The 14C and 13C signatures suggest sedimentary organic matter to be the dominant source of DOC in process (2). Our data provide a unique insight into the active transformation of DOC and sedimentary organic matter in the subsurface.

  17. A method for quantifying bioavailable organic carbon in aquifer sediments

    USGS Publications Warehouse

    Rectanus, H.V.; Widdowson, M.; Novak, J.; Chapelle, F.

    2005-01-01

    The fact that naturally occurring microorganisms can biodegrade PCE and TCE allows the use of monitored natural attenuation (MNA) as a remediation strategy at chlorinated solvent-contaminated sites. Research at numerous chlorinated solvent sites indicates an active dechlorinating microbial population coupled with an ample supply of organic carbon are conditions needed to sustain reductive dechlorination. A series of extraction experiments was used to compare the ability of the different extractants to remove organic carbon from aquifer sediments. The different extractants included pyrophosphate, sodium hydroxide, and polished water. Pyrophosphate served as a mild extractant that minimally alters the organic structure of the extracted material. Three concentrations (0.1, 0.5, and 1%) of pyrophosphate extracted 18.8, 24.9, and 30.8% of sediment organic carbon, respectively. Under alkali conditions (0.5 N NaOH), which provided the harshest extractant, 30.7% of the sediment organic carbon was recovered. Amorphous organic carbon, measured by potassium persulfate oxidization, consisted of 44.6% of the sediment organic carbon and served as a baseline control for maximum carbon removal. Conversely, highly purified water provided a minimal extraction control and extracted 5.7% of the sediment organic carbon. The removal of organic carbon was quantified by aqueous TOC in the extract and residual sediment organic carbon content. Characterization of the organic carbon extracts by compositional analysis prior and after exposure to the mixed culture might indicate the type organic carbon and functional groups used and/or generated by the organisms. This is an abstract of a paper presented at the 8th International In Situ and On-Site Bioremediation Symposium (Baltimore, MD 6/6-9/2005).

  18. [Soil organic carbon fractionation methods and their applications in farmland ecosystem research: a review].

    PubMed

    Zhang, Guo; Cao, Zhi-ping; Hu, Chan-juan

    2011-07-01

    Soil organic carbon is of heterogeneity in components. The active components are sensitive to agricultural management, while the inert components play an important role in carbon fixation. Soil organic carbon fractionation mainly includes physical, chemical, and biological fractionations. Physical fractionation is to separate the organic carbon into active and inert components based on the density, particle size, and its spatial distribution; chemical fractionation is to separate the organic carbon into various components based on the solubility, hydrolizability, and chemical reactivity of organic carbon in a variety of extracting agents. In chemical fractionation, the dissolved organic carbon is bio-available, including organic acids, phenols, and carbohydrates, and the acid-hydrolyzed organic carbon can be divided into active and inert organic carbons. Simulated enzymatic oxidation by using KMnO4 can separate organic carbon into active and non-active carbon. Biological fractionation can differentiate microbial biomass carbon and potential mineralizable carbon. Under different farmland management practices, the chemical composition and pool capacity of soil organic carbon fractions will have different variations, giving different effects on soil quality. To identify the qualitative or quantitative relationships between soil organic carbon components and carbon deposition, we should strengthen the standardization study of various fractionation methods, explore the integrated application of different fractionation methods, and sum up the most appropriate organic carbon fractionation method or the appropriate combined fractionation methods for different farmland management practices. PMID:22007474

  19. Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

    PubMed

    Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

    2016-04-01

    Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals <80% at <5,000 BV. In addition, breakthrough behavior was

  20. Effect of the adsorbate kinetic diameter on the accuracy of the Dubinin-Radushkevich equation for modeling adsorption of organic vapors on activated carbon.

    PubMed

    Jahandar Lashaki, Masoud; Fayaz, Mohammadreza; Niknaddaf, Saeid; Hashisho, Zaher

    2012-11-30

    This paper investigates the effect of the kinetic diameter (KD) of the reference adsorbate on the accuracy of the Dubinin-Radushkevich (D-R) equation for predicting the adsorption isotherms of organic vapors on microporous activated carbon. Adsorption isotherms for 13 organic compounds on microporous beaded activated carbon were experimentally measured, and predicted using the D-R model and affinity coefficients. The affinity coefficients calculated based on molar volumes, molecular polarizabilities, and molecular parachors were used to predict the isotherms based on four reference compounds (4.3≤KD≤6.8 Å). The results show that the affinity coefficients are independent of the calculation method if the reference and test adsorbates are from the same organic group. Choosing a reference adsorbate with a KD similar to that of the test adsorbate results in better prediction of the adsorption isotherm. The relative error between the predicted and the measured adsorption isotherms increases as the absolute difference in the kinetic diameters of the reference and test adsorbates increases. Finally, the proposed hypothesis was used to explain reports of inconsistent findings among published articles. The results from this study are important because they allow a more accurate prediction of adsorption capacities of adsorbents which allow for better design of adsorption systems. PMID:23044198

  1. [Relationships between soil organic carbon and environmental factors in gully watershed of the Loess Plateau].

    PubMed

    Wei, Xiao-Rong; Shao, Ming-An; Gao, Jian-Lun

    2008-10-01

    Understanding the distribution of organic carbon fractions in soils and their relationships with environmental factors are very important for appraising soil organic carbon status and assessing carbon cycling in the Loess Plateau. In this research, through field investigation and laboratory analysis, we studied the relationships between soil organic carbon and environmental factors in a gully watershed of the Loess Plateau. The environmental factors are landforms, land use conditions and soil types. The results showed that total soil organic carbon presented less variance, while high labile organic carbon presented greater variance. The variation coefficients of them are 34% and 43%, respectively, indicating that the variability of organic carbon in soils increased with the increasing of their activities. Total soil organic carbon, labile organic carbon, middle and high labile organic carbon were highly interrelated and presented similar distribution trend with environmental factors. Among different landforms, land uses, and soil types, the highest contents of organic carbon in different fractions were observed in plateau land, forest and farm lands, and black loessial soils, while the lowest contents of them were observed in gully bottom, grass land, and rubified soils, respectively. The relationships between organic carbon and environmental factors indicate that environmental factors not only directly influence the distribution of soil organic carbon, but also indirectly influence them through affecting the relationships among organic carbon fractions. The relationship between total organic carbon and labile organic carbon responses rapidly to environmental factors, while that between middle labile organic carbon and high labile organic carbon responses slowly to environmental factors. PMID:19143389

  2. APPRAISAL OF POWDERED ACTIVATED CARBON PROCESSES FOR MUNICIPAL WASTEWATER TREATMENT

    EPA Science Inventory

    Powdered activated carbon has been the subject of several developmental efforts directed towards producing improved methods for treating municipal wastewaters. Granular activated carbon has proven itself as an effective means of reducing dissolved organic contaminant levels, but ...

  3. Soil organic carbon across scales.

    PubMed

    O'Rourke, Sharon M; Angers, Denis A; Holden, Nicholas M; McBratney, Alex B

    2015-10-01

    Mechanistic understanding of scale effects is important for interpreting the processes that control the global carbon cycle. Greater attention should be given to scale in soil organic carbon (SOC) science so that we can devise better policy to protect/enhance existing SOC stocks and ensure sustainable use of soils. Global issues such as climate change require consideration of SOC stock changes at the global and biosphere scale, but human interaction occurs at the landscape scale, with consequences at the pedon, aggregate and particle scales. This review evaluates our understanding of SOC across all these scales in the context of the processes involved in SOC cycling at each scale and with emphasis on stabilizing SOC. Current synergy between science and policy is explored at each scale to determine how well each is represented in the management of SOC. An outline of how SOC might be integrated into a framework of soil security is examined. We conclude that SOC processes at the biosphere to biome scales are not well understood. Instead, SOC has come to be viewed as a large-scale pool subjects to carbon flux. Better understanding exists for SOC processes operating at the scales of the pedon, aggregate and particle. At the landscape scale, the influence of large- and small-scale processes has the greatest interaction and is exposed to the greatest modification through agricultural management. Policy implemented at regional or national scale tends to focus at the landscape scale without due consideration of the larger scale factors controlling SOC or the impacts of policy for SOC at the smaller SOC scales. What is required is a framework that can be integrated across a continuum of scales to optimize SOC management. PMID:25918852

  4. Measurements of ambient volatile organic carbons in rural, urban and areas with oil and gas activity in North Dakota

    NASA Astrophysics Data System (ADS)

    Hecobian, A.; Prenni, A. J.; Day, D.; Zhou, Y.; Sive, B. C.; Schichtel, B. A.; Collett, J. L., Jr.

    2014-12-01

    Recent increases in oil and gas extraction activities and well counts in North Dakota have raised questions on the ambient impact of the emissions from these processes. A Chevy Tahoe SUV was equipped with a PICARRO G2203 analyzer to measure methane and acetylene, a PICARRO A0941 mobile kit to measure GPS coordinates, an AethLabs micro-aethalometer to measure black carbon concentrations and a Radiance Research nephelometer to measure light scattering coefficient values. The SUV was used as a mobile platform to drive through different locations in North Dakota and measure the compounds noted above and also collect ambient air samples. The methane and acetylene concentrations were used to identify areas of interest, where evacuated stainless steel canisters were used to collect air samples and then transported to the laboratory where a three gas chromatograph system equipped with two flame ionization detectors (FID), two electron capture detectors (ECD), and a mass spectrometer (MS) was used to measure various VOC concentrations. The results from these measurements will be discussed here with an emphasis on the differences between rural and urban areas and locations with high instances oil and gas activities.

  5. Linear solvation energy relationship of the limiting partition coefficient of organic solutes between water and activated carbon

    USGS Publications Warehouse

    Luehrs, Dean C.; Hickey, James P.; Nilsen, Peter E.; Godbole, K.A.; Rogers, Tony N.

    1995-01-01

    A linear solvation energy relationship has been found for 353 values of the limiting adsorption coefficients of diverse chemicals:  log K = −0.37 + 0.0341Vi − 1.07β + D + 0.65P with R = 0.951, s = 0.51, n = 353, and F = 818.0, where Vi is the intrinsic molar volume; β is a measure of the hydrogen bond acceptor strength of the solute; D is an index parameter for the research group which includes the effects of the different types of carbon used, the temperature, and the length of time allowed for the adsorption equilibrium to be established; and P is an index parameter for the flatness of the molecule. P is defined to be unity if there is an aromatic system in the molecule or if there is a double bond or series of conjugated double bonds with no more that one non-hydrogen atom beyond the double bond and zero otherwise. A slightly better fit is obtained if the two-thirds power of Vi is used as a measure of the surface area in place of the volume term:  log K = −1.75 + 0.227V2/3 − 1.10β + D + 0.60P with R = 0.954, s = 0.49, n = 353, and F = 895.39. This is the first quantitative measure of the effect of the shape of the molecule on its tendency to be adsorbed on activated carbon.

  6. Effect of Organic Capping Layers over Monodisperse Platinum Nanoparticles upon Activity for Ethylene Hydrogenation and Carbon Monoxide Oxidation

    SciTech Connect

    Kuhn, John N.; Tsung, Chia-Kuang; Huang, Wenyu; Somorjai, Gabor A.

    2009-03-24

    The influence of oleylamine (OA), trimethyl tetradecyl ammonium bromide (TTAB), and polyvinlypyrrolidone (PVP) capping agents upon the catalytic properties of Pt/silica catalysts was evaluated. Pt nanoparticles that were 1.5 nm in size were synthesized by the same procedure (ethylene glycol reduction under basic conditions) with the various capping agents added afterward for stabilization. Before examining catalytic properties for ethylene hydrogenation and CO oxidation, the Pt NPs were deposited onto mesoporous silica (SBA-15) supports and characterized by transmission electron microscopy (TEM), H{sub 2} chemisorption, and elemental analysis (ICP-MS). PVP- and TTAB-capped Pt yielded mass-normalized reaction rates that decreased with increasing pretreatment temperature, and this trend was attributed to the partial coverage of the Pt surface with decomposition products from the organic capping agent. Once normalized to the Pt surface area, similar intrinsic activities were obtained regardless of the pretreatment temperature, which indicated no influence on the nature of the active sites. Consequently, a chemical probe technique using intrinsic activity for ethylene hydrogenation was demonstrated as an acceptable method for estimating the metallic surface areas of Pt. Amine (OA) capping exhibited a detrimental influence on the catalytic properties as severe deactivation and low activity were observed for ethylene hydrogenation and CO oxidation, respectively. These results were consistent with amine groups being strong poisons for Pt surfaces, and revealed the need to consider the effects of capping agents on the catalytic properties.

  7. Green Carbon, Black Carbon, White Carbon: Simultaneous Differentiation Between Soil Organic Matter, Pyrogenic Carbon and Carbonates Using Thermal Analysis Techniques

    NASA Astrophysics Data System (ADS)

    Plante, A. F.; Peltre, C.; Chan, J.; Baumgartl, T.; Erskine, P.; Apesteguía, M.; Virto, I.

    2014-12-01

    Quantification of soil carbon stocks and fluxes continues to be an important endeavor in assessments of soil quality, and more broadly in assessments of ecosystem functioning. The quantification of soil carbon in alkaline, carbonate-containing soils, such as those found in Mediterranean areas, is complicated by the need to differentiate between organic carbon (OC) and inorganic carbon (IC), which continues to present methodological challenges. Acidification is frequently used to eliminate carbonates prior to soil OC quantification, but when performed in the liquid phase, can promote the dissolution and loss of a portion of the OC. Acid fumigation (AF) is increasingly preferred for carbonate removal, but its effectiveness is difficult to assess using conventional elemental and isotopic analyses. The two-step approach is time, labor and cost intensive, and generates additional uncertainties from the calculations. Quantification of the actively cycling pool of soil organic C (SOC) in many soils is further complicated by the potential presence of more recalcitrant/stable forms such as pyrogenic or black carbon (BC) derived from incomplete combustion of vegetation, or even geogenic carbon such as coal. The wide spectrum of materials currently considered BC makes its quantification challenging. The chemical method using benzene polycarboxylic acids (BPCAs) as markers of condensed aromatic structures indicative of pyrogenic C is highly time, labor and cost intensive, and can generate artifacts. Several research groups are now developing method for the simultaneous identification and quantification of these various forms of soil carbon using thermal analysis techniques such as thermogravimetry, differential scanning calorimetry and evolved gas analysis. The objective of this presentation is to provide a general overview and specific examples of the current progress and technical challenges in this evolving methodology.

  8. SURVEY OF INDUSTRIAL APPLICATIONS OF VAPOR-PHASE ACTIVATED-CARBON ADSORPTION FOR CONTROL OF POLLUTANT COMPOUNDS FROM MANUFACTURE OF ORGANIC COMPOUNDS

    EPA Science Inventory

    This study covers industrial use of activated carbon for vapor-phase applications. A listing of over 700 applications of vapor-phase carbon systems is made available for use in identifying sites where a given compound is being removed.

  9. Preparation of activated carbon by chemical activation under vacuum.

    PubMed

    Juan, Yang; Ke-Qiang, Qiu

    2009-05-01

    Activated carbons especially used for gaseous adsorption were prepared from Chinesefir sawdust by zinc chloride activation under vacuum condition. The micropore structure, adsorption properties, and surface morphology of activated carbons obtained under atmosphere and vacuum were investigated. The prepared activated carbons were characterized by SEM, FTIR, and nitrogen adsorption. It was found that the structure of the starting material is kept after activation. The activated carbon prepared under vacuum exhibited higher values of the BET surface area (up to 1079 m2 g(-1)) and total pore volume (up to 0.5665 cm3 g(-1)) than those of the activated carbon obtained under atmosphere. This was attributed to the effect of vacuum condition that reduces oxygen in the system and limits the secondary reaction of the organic vapor. The prepared activated carbon has well-developed microstructure and high microporosity. According to the data obtained, Chinese fir sawdust is a suitable precursor for activated carbon preparation. The obtained activated carbon could be used as a low-cost adsorbent with favorable surface properties. Compared with the traditional chemical activation, vacuum condition demands less energy consumption, simultaneity, and biomass-oil is collected in the procedure more conveniently. FTIR analysis showed that heat treatment would result in the aromatization of the carbon structure. PMID:19534162

  10. Recycling of agricultural solid waste, coir pith: removal of anions, heavy metals, organics and dyes from water by adsorption onto ZnCl2 activated coir pith carbon.

    PubMed

    Namasivayam, C; Sangeetha, D

    2006-07-31

    The abundant lignocellulosic agricultural waste, coir pith is used to develop ZnCl(2) activated carbon and applied to the removal of toxic anions, heavy metals, organic compounds and dyes from water. Sorption of inorganic anions such as nitrate, thiocyanate, selenite, chromium(VI), vanadium(V), sulfate, molybdate, phosphate and heavy metals such as nickel(II) and mercury(II) has been studied. Removal of organics such as resorcinol, 4-nitrophenol, catechol, bisphenol A, 2-aminophenol, quinol, O-cresol, phenol and 2-chlorophenol has also been investigated. Uptake of acidic dyes such as acid brilliant blue, acid violet, basic dyes such as methylene blue, rhodamine B, direct dyes such as direct red 12B, congo red and reactive dyes such as procion red, procion orange were also examined to assess the possible use of the adsorbent for the treatment of contaminated ground water. Favorable conditions for maximum removal of all adsorbates at the adsorbate concentration of 20 mg/L were used. Results show that ZnCl(2) activated coir pith carbon is effective for the removal of toxic pollutants from water. PMID:16406295

  11. Effect of the secondary organic aerosol coatings on black carbon water uptake, cloud condensation nuclei activity, and particle collapse

    EPA Science Inventory

    The ability of black carbon aerosols to absorb water and act as a cloud condensation nuclei (CCN) directly controls their lifetime in the atmosphere as well as their impact on cloud formation, thus impacting the earth’s climate. Black carbon emitted from most combustion pro...

  12. Soil Organic Carbon Input from Urban Turfgrasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Turfgrass is a major vegetation type in the urban and suburban environment. Management practices such as species selection, irrigation, and mowing may affect carbon (C) input and storage in these systems. Research was conducted to determine the rate of soil organic carbon (SOC) changes, soil carbon ...

  13. Soil Organic Carbon Input from Urban Turfgrasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Turfgrass is a major vegetation type in the urban and suburban environment. Management practices such as species selection, irrigation, and mowing may affect carbon input and storage in these systems. Research was conducted to determine the rate of soil organic carbon (SOC) changes, soil carbon sequ...

  14. Dewatering Peat With Activated Carbon

    NASA Technical Reports Server (NTRS)

    Rohatgi, N. K.

    1984-01-01

    Proposed process produces enough gas and carbon to sustain itself. In proposed process peat slurry is dewatered to approximately 40 percent moisture content by mixing slurry with activated carbon and filtering with solid/liquid separation techniques.

  15. Suspended particulate matter fluxes along with their associated metals, organic matter and carbonates in a coastal Mediterranean area affected by mining activities.

    PubMed

    Helali, Mohamed Amine; Zaaboub, Noureddine; Oueslati, Walid; Added, Ayed; Aleya, Lotfi

    2016-03-15

    A study of suspended particulate matter (SPM) fluxes along with their associated metals, organic matter and carbonates, was conducted off the Mejerda River outlet in May 2011 and in March and July 2012 at depths of 10, 20 and 40 m using sediment traps. SPM fluxes are more significant near the Mejerda outlet, especially in winter, but dissipate further offshore. Normalization reveals that the Mejerda is a major source of Pb, Zn, Cd, Cu, Ni, and Co, all of which are the result of human activities. In contrast, Fe, Mn and N are of authigenic origin. The enrichment factor shows that Pb, Zn and especially Cd are the most highly polluting metals off the Mejerda outlet. This confirms the trend observed on the shores of the Mejerda prodelta and is consistent with the type of mining activities conducted in the Mejerda catchment. PMID:26869095

  16. Microorganisms and Organic Carbon in the Hhyper-Arid Mars-Like Soils and Their Correlation with Oxidant Activity

    NASA Astrophysics Data System (ADS)

    Valdivia-Silva, J. E.; Karouia, F.; McKay, C. P.

    2014-07-01

    Mars-like soil samples were analyzed for organic C and bacteria content. The microorganisms did not show any correlation with the organics, however, presented a significant dependence on changes in the capacity of decomposition of sodium formate.

  17. Soil organic carbon (SOC) accumulation in rice paddies under long-term agro-ecosystem experiments in southern China - VI. Changes in microbial community structure and respiratory activity

    NASA Astrophysics Data System (ADS)

    Liu, D.; Liu, X.; Liu, Y.; Li, L.; Pan, G.; Crowley, D.; Tippkötter, R.

    2011-02-01

    Biological stabilization within accumulated soil organic carbon (SOC) has not been well understood, while its role in physical and chemical protection as well as of chemical recalcitrance had been addressed in Chinese rice paddies. In this study, topsoil samples were collected and respiratory activity measured in situ following rice harvest under different fertilization treatments of three long-term experimental sites across southern China in 2009. The SOC contents, microbial biomass carbon (SMBC) and nitrogen (SMBN) were analysed using chemical digestion and microbial community structure assessment via clony dilute plate counting methods. While SOC contents were consistently higher under compound chemical fertilization (Comp-Fert) or combined organic and inorganic fertilization (Comb-Fert) compared to N fertilization only (N-Fert), there was significantly higher fungal-bacterial ratio under Comb-Fert than under N-Fert and Comp-Fert. When subtracting the background effect under no fertilization treatment (Non-Fert), the increase both in SMBC and SMBN under fertilization treatment was found very significantly correlated to the increase in SOC over controls across the sites. Also, the ratio of culturable fungal to bacterial population numbers (F/B ratio) was well correlated with soil organic carbon contents in all samples across the sites studied. SOC accumulation favoured a build-up the microbial community with increasing fungal dominance in the rice paddies under fertilization treatments. While soil respiration rates were high under Comb-Fert as a result of enhanced microbial community build-up, the specific soil respiratory activity based on microbial biomass carbon was found in a significantly negatively correlation with the SOC contents for overall samples. Thus, a fungal-dominated microbial community seemed to slow SOC turnover, thereby favouring SOC accumulation under Comp-Fert or under Comb-Fert in the rice paddies. Therefore, the biological stabilization

  18. Methods development for total organic carbon accountability

    NASA Technical Reports Server (NTRS)

    Benson, Brian L.; Kilgore, Melvin V., Jr.

    1991-01-01

    This report describes the efforts completed during the contract period beginning November 1, 1990 and ending April 30, 1991. Samples of product hygiene and potable water from WRT 3A were supplied by NASA/MSFC prior to contract award on July 24, 1990. Humidity condensate samples were supplied on August 3, 1990. During the course of this contract chemical analyses were performed on these samples to qualitatively determine specific components comprising, the measured organic carbon concentration. In addition, these samples and known standard solutions were used to identify and develop methodology useful to future comprehensive characterization of similar samples. Standard analyses including pH, conductivity, and total organic carbon (TOC) were conducted. Colorimetric and enzyme linked assays for total protein, bile acid, B-hydroxybutyric acid, methylene blue active substances (MBAS), urea nitrogen, ammonia, and glucose were also performed. Gas chromatographic procedures for non-volatile fatty acids and EPA priority pollutants were also performed. Liquid chromatography was used to screen for non-volatile, water soluble compounds not amenable to GC techniques. Methods development efforts were initiated to separate and quantitate certain chemical classes not classically analyzed in water and wastewater samples. These included carbohydrates, organic acids, and amino acids. Finally, efforts were initiated to identify useful concentration techniques to enhance detection limits and recovery of non-volatile, water soluble compounds.

  19. Simultaneous organic carbon and nitrogen removal in an anoxic-oxic activated sludge system under various operating conditions.

    PubMed

    Rasool, Kashif; Ahn, Dae Hee; Lee, Dae Sung

    2014-06-01

    This study investigated a bench-scale anoxic-oxic activated sludge system for integrated removal of COD and nitrogen. The experimental unit includes four chambers and continuous feeding in first chamber without recycle of nitrified liquid from aerobic to anoxic chamber unlike the conventional anoxic-oxic process. Recycled excessive sludge was used for the purpose of recycling nitrified mixed liquor. Synthetic wastewater with average loading rates of 0.53 kg COD/m(3)/d and 0.067 kg NH4(+)-N/m(3)/d was fed to the reactor system at hydraulic residence times (HRT) of 24 and 18 h. The results of 100 days operation showed high removal efficiencies of organic matter of about 97% as total COD and more than 99% removal of ammonia-nitrogen. In anoxic-oxic operation phase, total inorganic nitrogen (TIN) removal was about 66% by pre-denitrification. Moreover, the solid liquid separation through final clarifier was excellent without any suspended solid in the effluent. PMID:24768910

  20. Response of Bacterial Metabolic Activity to Riverine Dissolved Organic Carbon and Exogenous Viruses in Estuarine and Coastal Waters: Implications for CO2 Emission

    PubMed Central

    Xu, Jie; Sun, Mingming; Shi, Zhen; Harrison, Paul J.; Liu, Hongbin

    2014-01-01

    A cross-transplant experiment between estuarine water and seawater was conducted to examine the response of bacterial metabolic activity to riverine dissolved organic carbon (DOC) input under virus-rich and virus-free conditions, as well as to exogenous viruses. Riverine DOC input increased bacterial production significantly, but not bacterial respiration (BR) because of its high lability. The bioavailable riverine DOC influenced bulk bacterial respiration in two contrasting ways; it enhanced the bulk BR by stimulating bacterial growth, but simultaneously reduced the cell-specific BR due to its high lability. As a result, there was little stimulation of the bulk BR by riverine DOC. This might be partly responsible for lower CO2 degassing fluxes in estuaries receiving high sewage-DOC that is highly labile. Viruses restricted microbial decomposition of riverine DOC dramatically by repressing the growth of metabolically active bacteria. Bacterial carbon demand in the presence of viruses only accounted for 7–12% of that in the absence of viruses. Consequently, a large fraction of riverine DOC was likely transported offshore to the shelf. In addition, marine bacteria and estuarine bacteria responded distinctly to exogenous viruses. Marine viruses were able to infect estuarine bacteria, but not as efficiently as estuarine viruses, while estuarine viruses infected marine bacteria as efficiently as marine viruses. We speculate that the rapid changes in the viral community due to freshwater input destroyed the existing bacteria-virus relationship, which would change the bacterial community composition and affect the bacterial metabolic activity and carbon cycling in this estuary. PMID:25036641

  1. Mobility of organic carbon from incineration residues

    SciTech Connect

    Ecke, Holger Svensson, Malin

    2008-07-01

    Dissolved organic carbon (DOC) may affect the transport of pollutants from incineration residues when landfilled or used in geotechnical construction. The leaching of dissolved organic carbon (DOC) from municipal solid waste incineration (MSWI) bottom ash and air pollution control residue (APC) from the incineration of waste wood was investigated. Factors affecting the mobility of DOC were studied in a reduced 2{sup 6-1} experimental design. Controlled factors were treatment with ultrasonic radiation, full carbonation (addition of CO{sub 2} until the pH was stable for 2.5 h), liquid-to-solid (L/S) ratio, pH, leaching temperature and time. Full carbonation, pH and the L/S ratio were the main factors controlling the mobility of DOC in the bottom ash. Approximately 60 weight-% of the total organic carbon (TOC) in the bottom ash was available for leaching in aqueous solutions. The L/S ratio and pH mainly controlled the mobilization of DOC from the APC residue. About 93 weight-% of TOC in the APC residue was, however, not mobilized at all, which might be due to a high content of elemental carbon. Using the European standard EN 13 137 for determination of total organic carbon (TOC) in MSWI residues is inappropriate. The results might be biased due to elemental carbon. It is recommended to develop a TOC method distinguishing between organic and elemental carbon.

  2. Influence of carbonization methods on the aromaticity of pyrogenic dissolved organic carbon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic carbon (DOC) components of soil amendments such as biochar will influence the fundamental soil chemistry including the metal speciation, nutrient availability, and microbial activity. Quantitative correlation is necessary between (i) pyrogenic DOC components of varying aromaticity...

  3. The relationship between soil heterotrophic activity, soil dissolved organic carbon (DOC) leachate, and catchment-scale DOC export in headwater catchments

    USGS Publications Warehouse

    Brooks, P.D.; McKnight, Diane M.; Bencala, K.E.

    1999-01-01

    Dissolved organic carbon (DOC) from terrestrial sources forms the major component of the annual carbon budget in many headwater streams. In high-elevation catchments in the Rocky Mountains, DOC originates in the upper soil horizons and is flushed to the stream primarily during spring snowmelt. To identify controls on the size of the mobile soil DOC pool available to be transported during the annual melt event, we measured soil DOC production across a range of vegetation communities and soil types together with catchment DOC export in paired watersheds in Summit County, Colorado. Both surface water DOC concentrations and watershed DOC export were lower in areas where pyrite weathering resulted in lower soil pH. Similarly, the amount of DOC leached from organic soils was significantly smaller (p < 0.01) at sites having low soil p H. Scaling point source measurements of DOC production and leaching to the two basins and assuming only vegetated areas contribute to DOC production, we calculated that the amount of mobile DOC available to be leached to surface water during melt was 20.3 g C m-2 in the circumneutral basin and 17.8 g C m-2 in the catchment characterized by pyrite weathering. The significant (r2 = 0.91 and p < 0.05), linear relationship between overwinter CO2 flux and the amount of DOC leached from upper soil horizons during snowmelt suggests that the mechanism for the difference in production of mobile DOC was heterotrophic processing of soil carbon in snow-covered soil. Furthermore, this strong relationship between over-winter heterotrophic activity and the size of the mobile DOC pool present in a range of soil and vegetation types provides a likely mechanism for explaining the interannual variability of DOC export observed in high-elevation catchments.

  4. DISINFECTION OF BACTERIA ATTACHED TO GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Heterotrophic plate count bacteria, coliform organisms, and pathogenic microorganisms attached to granular activated carbon (GAC) particles were examined for their susceptibility to chlorine disinfection. When these bacteria were grown on carbon particles and then disinfected wit...

  5. Coadsorption of organic compounds and water vapor on BPL activated carbon: 2. 1,1,2-trichloro-1,2,2-trifluoroethane and dichloromethane

    SciTech Connect

    Eissmann, R.N.; LeVan, M.D. . Dept. of Chemical Engineering)

    1993-11-01

    A novel volumetric apparatus is used to measure equilibria for mixed vapors of halocarbons and water coadsorbed on BPL activated carbon. Pure-component 1,1,2-trichloro-1,2,2-trifluoroethane (CFC 113) and dichloromethane (methylene chloride) isotherms are obtained at 0, 25, 50, 75, and 100 C over wide ranges of pressure. A separate isotherm measured for CFC-113 at 50 C indicates the presence of pure component hysteresis in the mesopore structure of the activated carbon at high halocarbon loadings. Mixture equilibria are measured for CFC-113/water systems at 25 and 100 C and for dichloromethane/water systems at 25 C. All components exhibit hysteresis, and the halocarbon partial pressure increases as the water loading is increased at constant halocarbon loading. Results for halocarbon/water mixtures together with previous results for hydrocarbon/water mixtures show that the apparent total pore volume filled near saturation is dependent on the adsorption temperature and the solubility of the organic compound in water.

  6. Cloud condensation nuclei (CCN) activity and oxygen-to-carbon elemental ratios following thermodenuder treatment of organic particles grown by α-pinene ozonolysis.

    PubMed

    Kuwata, Mikinori; Chen, Qi; Martin, Scot T

    2011-08-28

    The effects of thermodenuder treatment on the cloud condensation nuclei (CCN) activity and elemental composition of organic particles grown by α-pinene ozonolysis were investigated. The secondary organic material (SOM) was produced in a continuous-flow chamber, with steady-state organic particle mass concentrations M(org) ranging from 1.4 to 37 μg m(-3). Particles exiting in the outflow were heated to temperatures T of up to 100 °C in a thermodenuder. The oxygen-to-carbon (O:C) and hydrogen-to-carbon (H:C) ratios were measured by on-line mass spectrometry. The observed elemental ratios were fit by a linear function, given by (H:C) = -0.8 (O:C) +1.8 for 0.38 < O:C < 0.50. This fit included the dependence on both M(org) and T, meaning that the single variable of post-thermodenuder M(org) was sufficient as an accurate predictor for O:C(M(org)(T)) and H:C(M(org)(T)). This result suggests that equilibrium partitioning theory largely governed the initial volatilization in the thermodenuder. By comparison, the CCN activity had a different dependence on thermodenuder treatment. At 25 °C, the CCN activity was independent of M(org), having an effective hygroscopicity parameter κ(org) of 0.103 ± 0.002. At 100 °C, however, κ(org) varied from 0.105 for M(org) = 1.4 μg m(-3) to 0.079 for M(org) = 37 μg m(-3), indicating that for high mass concentration the CCN activity decreased with heat treatment. The interpretation is that the oligomer fraction of the SOM increased at elevated T, both because of particle-phase reactions that produced oligomers under those conditions and because of the relative enrichment of lower-volatility oligomers in the SOM accompanying the evaporation of higher-volatility monomers from the SOM. Oligomers have high effective molecular weights and thereby significantly influence CCN activity. The production rates of different types of oligomers depend on the types and concentrations of functional groups present in the SOM, which in turn are

  7. Impact of salinity on organic matter and nitrogen removal from a municipal wastewater RO concentrate using biologically activated carbon coupled with UV/H2O2.

    PubMed

    Pradhan, Shovana; Fan, Linhua; Roddick, Felicity A; Shahsavari, Esmaeil; Ball, Andrew S

    2016-05-01

    The concentrate streams generated from reverse osmosis (RO)-based municipal wastewater reclamation processes contain organic substances and nutrients at elevated concentrations, posing environmental and health risks on their disposal to confined receiving environments such as bays. The impact of salinity (TDS at 7, 10 and 16 g/L) of a RO concentrate (ROC) on the treatment efficiency of a biological activated carbon (BAC) system after pre-oxidation with UV/H2O2 was characterised in terms of removal of organic matter and nitrogen species, and the bacterial communities. Organic matter removal was comparable for the ROC over the tested salinity range, with 45-49% of DOC and 70-74% of UVA254 removed by the combined treatment. However, removal in total nitrogen (TN) was considerably higher for the ROC at the high salinity (TDS ∼ 16 mg/L) compared with the low (∼7 g/L) and medium salinity (∼10 g/L). Effective nitrification with high ammonium removal (>90%) was achieved at all salinity levels, whereas greater denitrification (39%) was obtained at high salinity than low (23%) and medium salinity (27%) which might suggest that the bacterial communities contributing to the greater denitrification were more halotolerant. Microbiological characterisation using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and culture based techniques showed that diversified bacterial communities were present in the BAC system as evident from different 16S rDNA. The major bacterial groups residing on the BAC media belonged to Bacillus (Firmicutes), Pseudomonas (γ-Proteobacteria), and Rhodococcus (Actinobacteria) for all salinity levels, confirming that these microbial communities could be responsible for carbon and nitrogen removal at the different salinity levels. This has implications in understanding the effectiveness and robustness of the BAC system over the salinity range of the ROC and so would be useful for optimising the treatment efficiency of

  8. Comparison of nutshell granular activated carbons to commercial adsorbents for the purge-and-trap gas chromatographic analysis of volatile organic compounds.

    PubMed

    Wartelle, L H; Marshall, W E; Toles, C A; Johns, M M

    2000-05-26

    Granular activated carbons (GACs) made from agricultural by-products were investigated as adsorbents for short path thermal desorption gas chromatographic analysis of selected polar and nonpolar organic compounds. GACs made from macadamia nut, black walnut and hazelnut shells were compared to four commercially available adsorbents, namely, Tenax TA, Carboxen 569, Carbosieve SIII and coconut charcoal for their properties in purge-and-trap analysis. Adsorption values and breakthrough volumes were calculated for compounds from C3 and C6-C10. GACs derived from macadamia nut shells were found to adsorb and desorb between 80% (benzene) and 277% (ethylbenzene) more acetone (C3), benzene (C6), toluene (C7), ethyl- (C8), n-propyl- (C9), or sec.-butylbenzenes (C10) purged from water at the 100 ppb level than the commercial adsorbents tested. PMID:10893033

  9. [Effects of straw application and earthworm inoculation on soil labile organic carbon].

    PubMed

    Yu, Jian-Guang; Li, Hui Xin; Chen, Xiao-Yun; Hu, Feng

    2007-04-01

    A six-year field plot experiment of rice-wheat rotation was conducted to study the effects of straw application and earthworm inoculation on cropland soil organic carbon and labile organic carbon. Five treatments were installed, i.e., CK, straw mulch (M), straw mulch plus earthworm inoculation (ME), incorporated straw with soil (I), and incorporated straw with soil plus earthworm inoculation (IE). The results showed that soil organic carbon content increased significantly after six years straw application, and treatment I was more efficient than treatment M. Earthworm inoculation under straw application had no significant effects on soil organic carbon content. Straw application, whether straw mulch or incorporated straw with soil, increased the content of soil labile organic carbon, and incorporated straw with soil was more beneficial to the increase of the contents of hot water-extractable carbon, potentially mineralizable carbon, acid-extractable carbon, readily oxidizable carbon, particulate organic carbon, and light fraction organic carbon. There was a little relationship between the quantitative variations of soil dissoluble organic carbon and microbial biomass carbon and the patterns of straw application. Among the treatments, the activity of soil organic carbon was decreased in the order of IF > I > M > ME > CK. Straw application pattern was the main factor affecting soil organic carbon and labile organic carbon, while earthworm inoculation was not universally significanfly effective to all kinds of soil labile organic carbon. PMID:17615878

  10. Making Activated Carbon by Wet Pressurized Pyrolysis

    NASA Technical Reports Server (NTRS)

    Fisher, John W.; Pisharody, Suresh; Wignarajah, K.; Moran, Mark

    2006-01-01

    A wet pressurized pyrolysis (wet carbonization) process has been invented as a means of producing activated carbon from a wide variety of inedible biomass consisting principally of plant wastes. The principal intended use of this activated carbon is room-temperature adsorption of pollutant gases from cooled incinerator exhaust streams. Activated carbon is highly porous and has a large surface area. The surface area depends strongly on the raw material and the production process. Coconut shells and bituminous coal are the primary raw materials that, until now, were converted into activated carbon of commercially acceptable quality by use of traditional production processes that involve activation by use of steam or carbon dioxide. In the wet pressurized pyrolysis process, the plant material is subjected to high pressure and temperature in an aqueous medium in the absence of oxygen for a specified amount of time to break carbon-oxygen bonds in the organic material and modify the structure of the material to obtain large surface area. Plant materials that have been used in demonstrations of the process include inedible parts of wheat, rice, potato, soybean, and tomato plants. The raw plant material is ground and mixed with a specified proportion of water. The mixture is placed in a stirred autoclave, wherein it is pyrolized at a temperature between 450 and 590 F (approximately between 230 and 310 C) and a pressure between 1 and 1.4 kpsi (approximately between 7 and 10 MPa) for a time between 5 minutes and 1 hour. The solid fraction remaining after wet carbonization is dried, then activated at a temperature of 500 F (260 C) in nitrogen gas. The activated carbon thus produced is comparable to commercial activated carbon. It can be used to adsorb oxides of sulfur, oxides of nitrogen, and trace amounts of hydrocarbons, any or all of which can be present in flue gas. Alternatively, the dried solid fraction can be used, even without the activation treatment, to absorb

  11. Carbon nanotube electrodes in organic transistors.

    PubMed

    Valitova, Irina; Amato, Michele; Mahvash, Farzaneh; Cantele, Giovanni; Maffucci, Antonio; Santato, Clara; Martel, Richard; Cicoira, Fabio

    2013-06-01

    The scope of this Minireview is to provide an overview of the recent progress on carbon nanotube electrodes applied to organic thin film transistors. After an introduction on the general aspects of the charge injection processes at various electrode-semiconductor interfaces, we discuss the great potential of carbon nanotube electrodes for organic thin film transistors and the recent achievements in the field. PMID:23639944

  12. Floodplain Organic Carbon Storage in the Central Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Lininger, K.; Wohl, E.

    2014-12-01

    Floodplain storage of organic carbon is an important aspect of the global carbon cycle that is not well understood or quantified. Although it is understood that rivers transport organic carbon to the ocean, little is known about the quantity of stored carbon in boreal floodplains and the influence of fluvial processes on this storage. We present results on total organic carbon (TOC) content within the floodplains of two rivers, the Dall River and Preacher Creek, in the central Yukon River Basin in the Yukon Flats National Wildlife Refuge of Alaska. The results indicate that organic carbon storage is influenced by fluvial disturbance and grain size. The Dall River, which contains a large amount of floodplain carbon, is meandering and incised, with well-developed floodplain soils, a greater percentage of relatively old floodplain surfaces and a slower floodplain turnover time, and finer grain sizes. Preacher Creek stores less TOC, transports coarser grain sizes, and has higher rates of avulsion and floodplain turnover time. Within the floodplain of a particular river, large spatial heterogeneity in TOC content also exists as a function of depositional environment and age and vegetation community of the site. In addition, saturated regions of the floodplains, such as abandoned channels and oxbow lakes, contain more TOC compared to drier floodplain environments. Frozen alluvial soils likely contain carbon that could be released into the environment with melting permafrost, and thus quantifying the organic carbon content in the active layer of floodplain soils could provide insight into the characteristics of the permafrost beneath. The hydrology in these regions is changing due to permafrost melt, and floodplain areas usually saturated could be dried out, causing breakdown and outgassing of carbon stored in previously saturated soils. Ongoing work will result in a first-order estimate of active-layer floodplain carbon storage for the central Yukon River Basin.

  13. Efficient organic carbon burial in the Bengal fan sustained by the Himalayan erosional system.

    PubMed

    Galy, Valier; France-Lanord, Christian; Beyssac, Olivier; Faure, Pierre; Kudrass, Hermann; Palhol, Fabien

    2007-11-15

    Continental erosion controls atmospheric carbon dioxide levels on geological timescales through silicate weathering, riverine transport and subsequent burial of organic carbon in oceanic sediments. The efficiency of organic carbon deposition in sedimentary basins is however limited by the organic carbon load capacity of the sediments and organic carbon oxidation in continental margins. At the global scale, previous studies have suggested that about 70 per cent of riverine organic carbon is returned to the atmosphere, such as in the Amazon basin. Here we present a comprehensive organic carbon budget for the Himalayan erosional system, including source rocks, river sediments and marine sediments buried in the Bengal fan. We show that organic carbon export is controlled by sediment properties, and that oxidative loss is negligible during transport and deposition to the ocean. Our results indicate that 70 to 85 per cent of the organic carbon is recent organic matter captured during transport, which serves as a net sink for atmospheric carbon dioxide. The amount of organic carbon deposited in the Bengal basin represents about 10 to 20 per cent of the total terrestrial organic carbon buried in oceanic sediments. High erosion rates in the Himalayas generate high sedimentation rates and low oxygen availability in the Bay of Bengal that sustain the observed extreme organic carbon burial efficiency. Active orogenic systems generate enhanced physical erosion and the resulting organic carbon burial buffers atmospheric carbon dioxide levels, thereby exerting a negative feedback on climate over geological timescales. PMID:18004382

  14. Bromodeoxyuridine (BrdU) labeling and subsequent fluorescence activated cell sorting for culture-independent identification of dissolved organic carbon-degrading bacterioplankton.

    PubMed

    Robbins, Steven; Jacob, Jisha; Lu, Xinxin; Moran, Mary Ann; Mou, Xiaozhen

    2011-01-01

    Microbes are major agents mediating the degradation of numerous dissolved organic carbon (DOC) substrates in aquatic environments. However, identification of bacterial taxa that transform specific pools of DOC in nature poses a technical challenge. Here we describe an approach that couples bromodeoxyuridine (BrdU) incorporation, fluorescence activated cell sorting (FACS), and 16S rRNA gene-based molecular analysis that allows culture-independent identification of bacterioplankton capable of degrading a specific DOC compound in aquatic environments. Triplicate bacterioplankton microcosms are set up to receive both BrdU and a model DOC compound (DOC amendments), or only BrdU (no-addition control). BrdU substitutes the positions of thymidine in newly synthesized bacterial DNA and BrdU-labeled DNA can be readily immunodetected. Through a 24-hr incubation, bacterioplankton that are able to use the added DOC compound are expected to be selectively activated, and therefore have higher levels of BrdU incorporation (HI cells) than non-responsive cells in the DOC amendments and cells in no-addition controls (low BrdU incorporation cells, LI cells). After fluorescence immunodetection, HI cells are distinguished and physically separated from the LI cells by fluorescence activated cell sorting (FACS). Sorted DOC-responsive cells (HI cells) are extracted for DNA and taxonomically identified through subsequent 16S rRNA gene-based analyses including PCR, clone library construction and sequencing. PMID:21931294

  15. Bromodeoxyuridine (BrdU) Labeling and Subsequent Fluorescence Activated Cell Sorting for Culture-independent Identification of Dissolved Organic Carbon-degrading Bacterioplankton

    PubMed Central

    Lu, Xinxin; Moran, Mary Ann; Mou, Xiaozhen

    2011-01-01

    Microbes are major agents mediating the degradation of numerous dissolved organic carbon (DOC) substrates in aquatic environments. However, identification of bacterial taxa that transform specific pools of DOC in nature poses a technical challenge. Here we describe an approach that couples bromodeoxyuridine (BrdU) incorporation, fluorescence activated cell sorting (FACS), and 16S rRNA gene-based molecular analysis that allows culture-independent identification of bacterioplankton capable of degrading a specific DOC compound in aquatic environments. Triplicate bacterioplankton microcosms are set up to receive both BrdU and a model DOC compound (DOC amendments), or only BrdU (no-addition control). BrdU substitutes the positions of thymidine in newly synthesized bacterial DNA and BrdU-labeled DNA can be readily immunodetected 1,2. Through a 24-hr incubation, bacterioplankton that are able to use the added DOC compound are expected to be selectively activated, and therefore have higher levels of BrdU incorporation (HI cells) than non-responsive cells in the DOC amendments and cells in no-addition controls (low BrdU incorporation cells, LI cells). After fluorescence immunodetection, HI cells are distinguished and physically separated from the LI cells by fluorescence activated cell sorting (FACS) 3. Sorted DOC-responsive cells (HI cells) are extracted for DNA and taxonomically identified through subsequent 16S rRNA gene-based analyses including PCR, clone library construction and sequencing. PMID:21931294

  16. Carbon- and Nitrogen-Based Organic Frameworks.

    PubMed

    Sakaushi, Ken; Antonietti, Markus

    2015-06-16

    application, the framework/N approach as such is still in its infancy and has already moved organic materials to regions where otherwise only traditional noble metals or special inorganic semiconductors are found. As one potential way to enhance the properties of polymeric frameworks, the idea of catalysts having unique active surfaces based on Mott-Schottky heterojunctions and related concepts are addressed. In order to integrate all of the above versatile subjects from synthesis to applications on C,N-based organic frameworks, we begin the discussion with synthetic concepts and strategies for these frameworks to distinguish these systems from typical covalent organic frameworks based on boron oxide rings. Next we focus on the semiconducting properties of C,N-based organic frameworks in order to show a continuous transition between CTFs and other systems, such as graphitic carbon nitrides. At the end, applications of these materials are shown by highlighting their properties in electrochemical energy storage and photo- and electrocatalysis. PMID:26000989

  17. Worldwide organic soil carbon and nitrogen data

    SciTech Connect

    Zinke, P.J.; Stangenberger, A.G.; Post, W.M.; Emanual, W.R.; Olson, J.S.

    1986-09-01

    The objective of the research presented in this package was to identify data that could be used to estimate the size of the soil organic carbon pool under relatively undisturbed soil conditions. A subset of the data can be used to estimate amounts of soil carbon storage at equilibrium with natural soil-forming factors. The magnitude of soil properties so defined is a resulting nonequilibrium values for carbon storage. Variation in these values is due to differences in local and geographic soil-forming factors. Therefore, information is included on location, soil nitrogen content, climate, and vegetation along with carbon density and variation.

  18. Powdered activated carbon coupled with enhanced coagulation for natural organic matter removal and disinfection by-product control: application in a Western Australian water treatment plant.

    PubMed

    Kristiana, Ina; Joll, Cynthia; Heitz, Anna

    2011-04-01

    The removal of organic precursors of disinfection by-products (DBPs), i.e. natural organic matter (NOM), prior to disinfection and distribution is considered as the most effective approach to minimise the formation of DBPs. This study investigated the impact of the addition of powdered activated carbon (PAC) to an enhanced coagulation treatment process at an existing water treatment plant on the efficiency of NOM removal, the disinfection behaviour of the treated water, and the water quality in the distribution system. This is the first comprehensive assessment of the efficacy of plant-scale application of PAC combined with enhanced coagulation on an Australian source water. As a result of the PAC addition, the removal of NOM improved by 70%, which led to a significant reduction (80-95%) in the formation of DBPs. The water quality in the distribution system also improved, indicated by lower concentrations of DBPs in the distribution system and better maintenance of disinfectant residual at the extremities of the distribution system. The efficacy of the PAC treatment for NOM removal was shown to be a function of the characteristics of the NOM and the quality of the source water, as well as the PAC dose. PAC treatment did not have the capacity to remove bromide ion, resulting in the formation of more brominated DBPs. Since brominated DBPs have been found to be more toxic than their chlorinated analogues, their preferential formation upon PAC addition must be considered, especially in source waters containing high concentrations of bromide. PMID:21353285

  19. Quantitative structure-property relationship (QSPR) for the adsorption of organic compounds onto activated carbon cloth: Comparison between multiple linear regression and neural network

    SciTech Connect

    Brasquet, C.; Bourges, B.; Le Cloirec, P.

    1999-12-01

    The adsorption of 55 organic compounds is carried out onto a recently discovered adsorbent, activated carbon cloth. Isotherms are modeled using the Freundlich classical model, and the large database generated allows qualitative assumptions about the adsorption mechanism. However, to confirm these assumptions, a quantitative structure-property relationship methodology is used to assess the correlations between an adsorbability parameter (expressed using the Freundlich parameter K) and topological indices related to the compounds molecular structure (molecular connectivity indices, MCI). This correlation is set up by mean of two different statistical tools, multiple linear regression (MLR) and neural network (NN). A principal component analysis is carried out to generate new and uncorrelated variables. It enables the relations between the MCI to be analyzed, but the multiple linear regression assessed using the principal components (PCs) has a poor statistical quality and introduces high order PCs, too inaccurate for an explanation of the adsorption mechanism. The correlations are thus set up using the original variables (MCI), and both statistical tools, multiple linear regression and neutral network, are compared from a descriptive and predictive point of view. To compare the predictive ability of both methods, a test database of 10 organic compounds is used.

  20. Erosion of soil organic carbon: implications for carbon sequestration

    USGS Publications Warehouse

    Van Oost, Kristof; Van Hemelryck, Hendrik; Harden, Jennifer W.

    2009-01-01

    Agricultural activities have substantially increased rates of soil erosion and deposition, and these processes have a significant impact on carbon (C) mineralization and burial. Here, we present a synthesis of erosion effects on carbon dynamics and discuss the implications of soil erosion for carbon sequestration strategies. We demonstrate that for a range of data-based parameters from the literature, soil erosion results in increased C storage onto land, an effect that is heterogeneous on the landscape and is variable on various timescales. We argue that the magnitude of the erosion term and soil carbon residence time, both strongly influenced by soil management, largely control the strength of the erosion-induced sink. In order to evaluate fully the effects of soil management strategies that promote carbon sequestration, a full carbon account must be made that considers the impact of erosion-enhanced disequilibrium between carbon inputs and decomposition, including effects on net primary productivity and decomposition rates.

  1. Separating proteins with activated carbon.

    PubMed

    Stone, Matthew T; Kozlov, Mikhail

    2014-07-15

    Activated carbon is applied to separate proteins based on differences in their size and effective charge. Three guidelines are suggested for the efficient separation of proteins with activated carbon. (1) Activated carbon can be used to efficiently remove smaller proteinaceous impurities from larger proteins. (2) Smaller proteinaceous impurities are most efficiently removed at a solution pH close to the impurity's isoelectric point, where they have a minimal effective charge. (3) The most efficient recovery of a small protein from activated carbon occurs at a solution pH further away from the protein's isoelectric point, where it is strongly charged. Studies measuring the binding capacities of individual polymers and proteins were used to develop these three guidelines, and they were then applied to the separation of several different protein mixtures. The ability of activated carbon to separate proteins was demonstrated to be broadly applicable with three different types of activated carbon by both static treatment and by flowing through a packed column of activated carbon. PMID:24898563

  2. EPA'S RESEARCH PROGRAM IN GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Research into Granular Activated Carbon (GAC) for use in drinking water treatment has a long history in the Drinking Water Research Division and its predecessor organizations. tudies were conducted by the U.S. Public Health Service in the late fifties and early sixties to examine...

  3. USING POWDERED ACTIVATED CARBON: A CRITICAL REVIEW

    EPA Science Inventory

    Because the performance of powdered activated carbon (PAC) for uses other than taste and odor control is poorly documented, the purpose of this article is to critically review uses that have been reported (i.e., pesticides and herbicides, synthetic organic chemicals, and trihalom...

  4. ACTIVATED CARBON TREATMENT OF KRAFT BLEACHING EFFLUENTS

    EPA Science Inventory

    The removal of color and organic contaminants by adsorption on activated carbon from the effluent of a kraft pulp bleaching plant was investigated in a pilot plant. The caustic bleach effluent, which contains 80% of the color from pulp bleaching, was decolorized successfully when...

  5. Simultaneous Removal of Nitrate and Natural Organic Matter from Drinking Water Using a Hybrid Heterotrophic/Autotrophic/Biological Activated Carbon Bioreactor

    PubMed Central

    Saeedi, Reza; Naddafi, Kazem; Nabizadeh, Ramin; Mesdaghinia, Alireza; Nasseri, Simin; Alimohammadi, Mahmood; Nazmara, Shahrokh

    2012-01-01

    Abstract Simultaneous removal of nitrate (\\documentclass{aastex}\\usepackage{amsbsy}\\usepackage{amsfonts}\\usepackage{amssymb}\\usepackage{bm}\\usepackage{mathrsfs}\\usepackage{pifont}\\usepackage{stmaryrd}\\usepackage{textcomp}\\usepackage{portland, xspace}\\usepackage{amsmath, amsxtra}\\pagestyle{empty}\\DeclareMathSizes {10} {9} {7} {6}\\begin{document} $${\\rm NO}_3^{-}$$ \\end{document}) and natural organic matter (NOM) from drinking water using a hybrid heterotrophic/autotrophic/BAC bioreactor (HHABB) was studied in continuous mode. The HHABB consisted of three compartments: ethanol heterotrophic part, sulfur autotrophic part, and biological activated carbon (BAC)-part (including anoxic and aerobic sections). Experiments were performed with \\documentclass{aastex}\\usepackage{amsbsy}\\usepackage{amsfonts}\\usepackage{amssymb}\\usepackage{bm}\\usepackage{mathrsfs}\\usepackage{pifont}\\usepackage{stmaryrd}\\usepackage{textcomp}\\usepackage{portland, xspace}\\usepackage{amsmath, amsxtra}\\pagestyle{empty}\\DeclareMathSizes {10} {9} {7} {6}\\begin{document} $${\\rm NO}_3^{-}$$ \\end{document} concentration 30 mg N/L, \\documentclass{aastex}\\usepackage{amsbsy}\\usepackage{amsfonts}\\usepackage{amssymb}\\usepackage{bm}\\usepackage{mathrsfs}\\usepackage{pifont}\\usepackage{stmaryrd}\\usepackage{textcomp}\\usepackage{portland, xspace}\\usepackage{amsmath, amsxtra}\\pagestyle{empty}\\DeclareMathSizes {10} {9} {7} {6}\\begin{document} $${\\rm NO}_3^{-}$$ \\end{document} loading rate 0.72 kg N/m3/d, C : N ratio 0.53, and three concentrations of NOM (0.6, 2.6, and 5.7 mg C/L). Overall denitrification rate and efficiency of the HHABB were not affected by NOM concentration and were in the suitable ranges of 0.69–0.70 kg N/m3/d and 96.0%–97.7%, respectively. NOM removal at concentration 0.6 mg C/L was not efficient because of organic carbon replacement as soluble microbial products. At higher NOM concentrations, total NOM removal efficiencies were 55%

  6. Removal of dissolved organic matter by granular-activated carbon adsorption as a pretreatment to reverse osmosis of membrane bioreactor effluents.

    PubMed

    Gur-Reznik, Shirra; Katz, Ilan; Dosoretz, Carlos G

    2008-03-01

    The adsorption of dissolved organic matter (DOM) on granular-activated carbon (GAC) as a pretreatment to reverse osmosis (RO) desalination of membrane bioreactor (MBR) effluents was studied in lab- and pilot-scale columns. The pattern and efficiency of DOM adsorption and fate of the hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) fractions were characterized, as well as their impact on organic fouling of the RO membranes. Relatively low DOM adsorption capacity and low intensity of adsorption were observed in batch studies. Continuous adsorption experiments performed within a range of hydraulic velocities of 0.9-12m/h depicted permissible values within the mass transfer zone up to 1.6m/h. The breakthrough curves within this range displayed a non-adsorbable fraction of 24+/-6% and a biodegradable fraction of 49+/-12%. Interestingly, the adsorbable fraction remained almost constant ( approximately 30%) in the entire hydraulic range studied. Comparative analysis by HPO interaction chromatography showed a steady removal (63-66%) of the HPO fraction. SUVA index and Fourier Transform Infrared (FTIR) spectra indicated that DOM changes during the adsorption phase were mainly due to elution of the more HPI components. GAC pretreatment in pilot-scale columns resulted in 80-90% DOM removal from MBR effluents, which in turn stabilized membrane permeability and increased permeate quality. FTIR analysis indicated that the residual DOM present in the RO permeate, regardless of the pretreatment, was mainly of HPI character (e.g., low-molecular-weight humics linked to polysaccharides and proteins). The DOM removed by GAC pretreatment is composed mainly of HPO and biodegradable components, which constitutes the fraction primarily causing organic fouling. PMID:17980400

  7. Long-term impact of land management in soil biological processes can be assessed by fingerprint of dissolved organic carbon and peroxidase activity in topsoil and subsoil

    NASA Astrophysics Data System (ADS)

    Hernandez-Soriano, Maria C.; Maclean, Jamie L.; Dalal, Ram C.; Menzies, Neal W.; Kopittke, Peter M.

    2015-04-01

    The dissolved organic carbon (DOC) is a highly dynamic pool, directly related to biological functions and to the stabilization of organic carbon (OC) through interaction with the mineral phase. Therefore, the characterization of the main components of DOC can be linked to the metabolic status of soil and the turnover of OC and provides a sensitive approach to evaluate the impact of land use on OC turnover in soils. Accordingly, the objective of this study was to derive relationships between DOC characteristics and biochemical activity in soils under contrasting land management. The soil solution was isolated from topsoil and subsoil for three soils (Vertisol, Ferralsol, Acrisol, World Reference Base 2014) collected from undisturbed areas and from a location(s) immediately adjacent which has a long history of agricultural, pasture or afforestation use (>20 years) by centrifugation at 4000 rpm (20 min, 25 °C. The fingerprint of DOC was obtained to identify OC functionalities by spectrofluorometric analyses and Excitation-Emission matrices (EEM) were obtained for all samples. The excitation wavelengths were increased from 250 to 400 nm in 5-nm steps for each excitation wavelength, and emission was detected from 250 to 500 nm in 0.5-nm steps and. Humification index (HIX), freshness index (FrI), fluorescence index (FI) and redox index (RI) were derived from the EEMs. Extracellular laccase activity was examined by monitoring the oxidation of 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) at 420 nm. The EEMs revealed a depletion of the humic-like component (250

  8. Organic carbon biostimulates rapid rhizodegradation of perchlorate.

    PubMed

    Yifru, Dawit D; Nzengung, Valentine A

    2008-12-01

    Previous hydroponics and field studies identified phytodegradation and rhizodegradation as the two main mechanisms by which plants metabolize perchlorate. Plant uptake and phytodegradation of perchlorate is a slower and undesired process that poses ecological risks resulting from phytoaccumulation of some fraction of the perchlorate. Meanwhile, rhizodegradation is a more rapid and favored process involving perchlorate-degrading bacteria utilizing dissolved organic carbon (DOC) as a carbon and energy (electron) source to rapidly degrade perchlorate to innocuous chloride. In the present study, rhizodegradation of perchlorate by willow trees (Salix nigra) was biostimulated using electron sources obtained from natural and artificial carbon sources. In bioreactors provided with carbon sources as 500 mg/L DOC, 25 to 40 mg/L of initial perchlorate concentrations were removed to below the ion chromatography method detection limit of 2 microg/L in approximately 9 d. For planted controls provided with no electron donors, the time required for the complete removal of the same doses of perchlorate was up to 70 d. Enhancement of rhizodegradation by organic carbon reduced the phytoaccumulated fraction of perchlorate by an order of magnitude from approximately 430 to 20 mg/kg. The implication of the present study is that the high fraction uptake and phytoaccumulation of perchlorate in agricultural products and the recycling of perchlorate into the ecosystem can be significantly curtailed by supplying electron donors derived from organic carbon sources to the root zone of plants. PMID:18593217

  9. Effect of the adsorbate (Bromacil) equilibrium concentration in water on its adsorption on powdered activated carbon. Part 3: Competition with natural organic matter.

    PubMed

    Al Mardini, Fadi; Legube, Bernard

    2010-10-15

    This study (part 3) was carried out to investigate the effect of the natural organic matter (NOM) concentration on Bromacil (pesticide) adsorption on powdered activated carbon (PAC) in the same experimental conditions as in our previous studies (parts 1 and 2). Our previous findings showed that Bromacil adsorption in buffered pure water (pH 7.8) occurred at two types of site. In the presence of NOM (three kinds), we noted a significant reduction in Bromacil adsorption capacities due to the competitive effects exerted by NOM. Highly reactive sites (or pores) in PAC appeared to be blocked by NOM adsorption, as demonstrated by the application of a pseudo-single solute isotherm and of the simplified ideal adsorbed solution theory (IAST), regardless of the initial Bromacil and NOM concentrations. The competing effect of low-molecular weight NOM was found to be greater than the competing effect of high-molecular weight NOM. The pseudo-second order surface-reaction model fitted Bromacil adsorption particularly well, even in the presence of NOM. However, the adsorption-kinetic constant values were found to be independent of the aqueous equilibrium concentration of the target compound, contrary to that observed in pure water. The kinetic data thus confirmed that high reactivity PAC sites were blocked by NOM adsorption. A practical approach concluded this work. PMID:20619963

  10. Effects of sludge retention times on reactivity of effluent dissolved organic matter for trihalomethane formation in hybrid powdered activated carbon membrane bioreactors.

    PubMed

    Ma, Defang; Gao, Baoyu; Xia, Chufan; Wang, Yan; Yue, Qinyan; Li, Qian

    2014-08-01

    In this study, real municipal wastewater intended for reuse was treated by two identical hybrid PAC/MBRs (membrane bioreactors with powdered activated carbon addition), which were operated at sludge retention times (SRTs) of 30 and 180 days, respectively. In order to investigate the effects of SRT on trihalomethane (THM) formation in chlorinated PAC/MBR effluents, characteristics and THM formation reactivity of effluent dissolved organic matter (EfOM) at different SRTs were examined. PAC/MBR-180 had higher level of EfOM, which contained less simple aromatic proteins and exhibited lower specific UV absorbance. EfOM with molecular weight <5 kDa from PAC/MBR-30 (23%) was lower than PAC/MBR-180 (26%). About 50% of EfOM from PAC/MBR-30 was hydrophobic acids, which was higher than that from PAC/MBR-180 (about 36%). EfOM at SRT 180 days exhibited higher hydrophilicity. Prolonging SRT greatly reduced THM formation reactivity of EfOM, but increased the formation of bromine-containing species during chlorination of PAC/MBR effluents. PMID:24929809

  11. Fertilization increases paddy soil organic carbon density*

    PubMed Central

    Wang, Shao-xian; Liang, Xin-qiang; Luo, Qi-xiang; Fan, Fang; Chen, Ying-xu; Li, Zu-zhang; Sun, Huo-xi; Dai, Tian-fang; Wan, Jun-nan; Li, Xiao-jun

    2012-01-01

    Field experiments provide an opportunity to study the effects of fertilization on soil organic carbon (SOC) sequestration. We sampled soils from a long-term (25 years) paddy experiment in subtropical China. The experiment included eight treatments: (1) check, (2) PK, (3) NP, (4) NK, (5) NPK, (6) 7F:3M (N, P, K inorganic fertilizers+30% organic N), (7) 5F:5M (N, P, K inorganic fertilizers+50% organic N), (8) 3F:7M (N, P, K inorganic fertilizers+70% organic N). Fertilization increased SOC content in the plow layers compared to the non-fertilized check treatment. The SOC density in the top 100 cm of soil ranged from 73.12 to 91.36 Mg/ha. The SOC densities of all fertilizer treatments were greater than that of the check. Those treatments that combined inorganic fertilizers and organic amendments had greater SOC densities than those receiving only inorganic fertilizers. The SOC density was closely correlated to the sum of the soil carbon converted from organic amendments and rice residues. Carbon sequestration in paddy soils could be achieved by balanced and combined fertilization. Fertilization combining both inorganic fertilizers and organic amendments is an effective sustainable practice to sequestrate SOC. PMID:22467369

  12. Carbon aging mechanisms and effects on retention of organic iodides

    SciTech Connect

    Hyder, M.L.

    1985-01-01

    The activated carbon used to treat the off-gas from the Savannah River Plant prodution reactor building was studied to determine the chemical changes occurring in this carbon during its service life. The carbon is a coconut-shell charcoal impregnated with 1% triethylenediamine (TEDA) and 2% KI. It was known that during its 30-month service life the carbon becomes more acidic and less effective for retaining iodine in organic form. The study showed that the most important change occurring in the carbon is the reaction of KI to give other chemical forms of iodine. The reacted iodine is unavailable for exchange with alkyl iodides. The results suggest that the carbon reacts with KI to form organic compounds, but small amounts of oxidized iodine may also be presnt. There is also evidence that some iodide is lost from the carbon altogether. The TEDA impregnant is lost from the carbon very quickly, and has no importance after a few months. The specific reactions by which the impregnant is lost have not been identified. However, mathematical analysis shows that the carbon performance data are consistent with the reaction of iodide impregnant with impurities in the air flowing through the carbon bed. Additional mathematical analysis, based on electron microscopic observation of the carbon particles, indicates that the external surfaces of the carbon are mainly responsible for their effectiveness in retaining iodine. Consequently, the condition of the impregnants on a relatively small fraction of the carbon surface can have a large effect on its performance. 4 refs., 14 figs., 2 tabs.

  13. Determination of adsorbable organic fluorine from aqueous environmental samples by adsorption to polystyrene-divinylbenzene based activated carbon and combustion ion chromatography.

    PubMed

    Wagner, Andrea; Raue, Brigitte; Brauch, Heinz-Jürgen; Worch, Eckhard; Lange, Frank T

    2013-06-21

    A new method for the determination of trace levels of adsorbable organic fluorine (AOF) in water is presented. Even if the individual contributing target compounds are widely unknown, this surrogate parameter is suited to identify typical organofluorine contaminations, such as with polyfluorinated chemicals (PFCs), and represents a lower boundary of the organofluorine concentration in water bodies. It consists of the adsorption of organofluorine chemicals on a commercially available synthetic polystyrene-divinylbenzene based activated carbon (AC) followed by analysis of the loaded AC by hydropyrolysis combustion ion chromatography (CIC). Inorganic fluorine is displaced by excess nitrate during the extraction step and by washing the loaded activated carbon with an acidic sodium nitrate solution. Due to its high purity the synthetic AC had a very low and reproducible fluorine blank (0.3 μg/g) compared to natural ACs (up to approximately 9 μg/g). Using this AC, fluoride and the internal standard phosphate could be detected free of chromatographic interferences. With a sample volume of 100 mL and 2× 100 mg of AC packed into two extraction columns combined in series, a limit of quantification (LOQ), derived according to the German standard method DIN 32645, of 0.3 μg/L was achieved. The recoveries of six model PFCs were determined from tap water and a municipal wastewater treatment plant (WWTP) effluent. Except for the extremely polar perfluoroacetic acid (recovery of approximately 10%) the model substances showed fairly good (50% for perfluorobutanoic acid (PFBA)) to very good fluorine recoveries (100±20% for perfluorooctanoic acid (PFOA), perfluorobutanesulfonate (PFBS), 6:2 fluorotelomersulfonate (6:2 FTS)), both from tap water and wastewater matrix. This new analytical protocol was exemplarily applied to several surface water and groundwater samples. The obtained AOF values were compared to the fluorine content of 19 target PFCs analyzed by high performance

  14. Occupational exposure to complex mixtures of volatile organic compounds in ambient air: desorption from activated charcoal using accelerated solvent extraction can replace carbon disulfide?

    PubMed

    Fabrizi, Giovanni; Fioretti, Marzia; Rocca, Lucia Mainero

    2013-01-01

    A desorption study of 57 volatile organic compounds (VOCs) has been conducted by use of accelerated solvent extraction (ASE) and gas chromatography-mass spectrometry. Different solvents were tested to extract activated charcoal tubes with the objective of replacing carbon disulfide, used in official methods, because of its highly toxic health and environmental effects. Extraction conditions, for example temperature and number of cycles, were investigated and optimized. The definitive extraction procedure selected was use of acetone at 150 °C and two consecutive extraction cycles at a pressure of 1,500 psi. Considering a sample volume of 0.005 Nm(3), corresponding to a sampling time of 8 h at a flow rate of 0.01 L min(-1), the method was validated over the concentration range 65-26,300 μg Nm(-3). The lowest limit of quantification was 6 μg Nm(-3), and recovery for the 93 % of analytes ranged from 65 to 102 %. For most of the compounds, relative standard deviations were less than 15 % for inter and intra-day precision. Uncertainty of measurement was also determined: the relative expanded uncertainty was always below 29.6 %, except for dichlorodifluoromethane. This work shows that use of friendlier solvent, for example acetone, coupled with use of ASE, can replace use of CS(2) for chemical removal of VOCs from activated charcoal. ASE has several advantages over traditional solvent-extraction methods, including shorter extraction time, minimum sample manipulation, high reproducibility, and less extraction discrimination. No loss of sensitivity occurs and there is also a salutary effect on bench workers' health and on the smell of laboratory air. PMID:22968683

  15. Ultrasonically assisted hydrothermal synthesis of activated carbon-HKUST-1-MOF hybrid for efficient simultaneous ultrasound-assisted removal of ternary organic dyes and antibacterial investigation: Taguchi optimization.

    PubMed

    Azad, F Nasiri; Ghaedi, M; Dashtian, K; Hajati, S; Pezeshkpour, V

    2016-07-01

    Activated carbon (AC) composite with HKUST-1 metal organic framework (AC-HKUST-1 MOF) was prepared by ultrasonically assisted hydrothermal method and characterized by FTIR, SEM and XRD analysis and laterally was applied for the simultaneous ultrasound-assisted removal of crystal violet (CV), disulfine blue (DSB) and quinoline yellow (QY) dyes in their ternary solution. In addition, this material, was screened in vitro for their antibacterial actively against Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PAO1) bacteria. In dyes removal process, the effects of important variables such as initial concentration of dyes, adsorbent mass, pH and sonication time on adsorption process optimized by Taguchi approach. Optimum values of 4, 0.02g, 4min, 10mgL(-1) were obtained for pH, AC-HKUST-1 MOF mass, sonication time and the concentration of each dye, respectively. At the optimized condition, the removal percentages of CV, DSB and QY were found to be 99.76%, 91.10%, and 90.75%, respectively, with desirability of 0.989. Kinetics of adsorption processes follow pseudo-second-order model. The Langmuir model as best method with high applicability for representation of experimental data, while maximum mono layer adsorption capacity for CV, DSB and QY on AC-HKUST-1 estimated to be 133.33, 129.87 and 65.37mgg(-1) which significantly were higher than HKUST-1 as sole material with Qm to equate 59.45, 57.14 and 38.80mgg(-1), respectively. PMID:26964963

  16. Activated carbon to the rescue

    SciTech Connect

    Sen, S.

    1996-03-01

    This article describes the response to pipeline spill of ethylene dichloride (EDC) on the property of an oil company. Activated carbon cleanup proceedure was used. During delivery, changeout, transport, storage, thermal reactivation, and return delivery to the site, the carbon never came into direct contact with operating personnel or the atmosphere. More than 10,000 tones of dredge soil and 50 million gallons of surface water were processed during the emergency response.

  17. How to Enhance Soil Organic Carbon Sequestration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Optimizing crop yields and reducing soil erosion can enhance soil organic carbon (SOC) sequestration. The influence of management practices on crop residue C and N inputs to the soil, SOC sequestration, and NO3-N leaching potential under irrigated, continuous crop production in northern Texas was e...

  18. Charcoal bed operation for optimal organic carbon removal

    SciTech Connect

    Merritt, C.M.; Scala, F.R.

    1995-05-01

    Historically, evaporation, reverse osmosis or charcoal-demineralizer systems have been used to remove impurities in liquid radwaste processing systems. At Nine Mile point, we recently replaced our evaporators with charcoal-demineralizer systems to purify floor drain water. A comparison of the evaporator to the charcoal-demineralizer system has shown that the charcoal-demineralizer system is more effective in organic carbon removal. We also show the performance data of the Granulated Activated Charcoal (GAC) vessel as a mechanical filter. Actual data showing that frequent backflushing and controlled flow rates through the GAC vessel dramatically increases Total Organic Carbon (TOC) removal efficiency. GAC vessel dramatically increases Total Organic Carbon (TOC) removal efficiency. Recommendations are provided for operating the GAC vessel to ensure optimal performance.

  19. Remote Sensing to Support Monitoring of Soil Organic Carbon (Invited)

    NASA Astrophysics Data System (ADS)

    McNairn, H.; Pacheco, A.

    2009-12-01

    Soil organic carbon is fundamental to the sustainability of agricultural soils and soils play an important role in the global carbon balance. Estimating soil carbon levels and monitoring changes in these levels over time requires extensive data on climate, soil properties, land cover and land management. Remote sensing technologies are capable of providing some of the data needed in modeling soil organic carbon concentrations and in tracking changes in soil carbon. The characteristics of the vegetation cover influence the amount of organic matter in the soil and cultivation impacts the rate of organic matter decomposition. Consequently land management decisions, which include cropping and tillage practices, play a vital role in determining soil carbon levels. Agriculture and Agri-Food Canada (AAFC) has developed several methods to map land management practices from multispectral and Synthetic Aperture Radar (SAR) satellite sensors. These include identification of crops grown, estimation of crop residue cover left post-harvest and identification of tillage activities. Optical and SAR data are capable of identifying crop types to accuracies consistently above 85%. Knowledge of crop type also provides information needed to establish biomass levels and residue type, both of which influence the amounts and decomposition rates of organic matter. Scientists with AAFC have also extensively validated a method to estimate percent residue cover using spectral unmixing analysis applied to multispectral satellite data. Percentages for corn, soybean and small grain residues can be estimated to accuracies of 83%, 80% and 82%, respectively. Tillage activity influences residue decomposition and AAFC is investigating methods to identify tillage occurrence using advanced polarimetric SAR information. This presentation will provide an overview of methods and results from research ongoing at AAFC. The potential contribution of these remote sensing approaches to support wide area carbon

  20. The Quest for Organic Carbon on Mars

    NASA Technical Reports Server (NTRS)

    Eigenbrode, Jennifer

    2011-01-01

    We are entering an era of Mars exploration in which organic carbon detection, characterization, and structural identification will be key to addressing some of the outstanding science objectives of the Mars Exploration Program. Success of these missions will depend on technical, scientific, and strategic elements--all of which are strongly determined based on terrestrial experience and knowledge of organic matter formation, concentration, and preservation. Analog studies including Precambrian sediments, modern endolithic communities, and experiments help us fine-tune these approaches, but we also need to expect the unexpected. This presentation will provide perspective on the challenges of detecting organic carbon on Mars, how we may achieve such detections with the in situ instruments, such as the SAM (Science Analysis at Mars) instrument suite onboard Curiosity, the rover for the 2011 Mars Science Laboratory mission.

  1. Selecting activated carbon for water and wastewater treatability studies

    SciTech Connect

    Zhang, W.; Chang, Q.G.; Liu, W.D.; Li, B.J.; Jiang, W.X.; Fu, L.J.; Ying, W.C.

    2007-10-15

    A series of follow-up investigations were performed to produce data for improving the four-indicator carbon selection method that we developed to identify high-potential activated carbons effective for removing specific organic water pollutants. The carbon's pore structure and surface chemistry are dependent on the raw material and the activation process. Coconut carbons have relatively more small pores than large pores; coal and apricot nutshell/walnut shell fruit carbons have the desirable pore structures for removing adsorbates of all sizes. Chemical activation, excessive activation, and/or thermal reactivation enlarge small pores, resulting in reduced phenol number and higher tannic acid number. Activated carbon's phenol, iodine, methylene blue, and tannic acid numbers are convenient indicators of its surface area and pore volume of pore diameters < 10, 10-15, 15-28, and > 28 angstrom, respectively. The phenol number of a carbon is also a good indicator of its surface acidity of oxygen-containing organic functional groups that affect the adsorptive capacity for aromatic and other small polar organics. The tannic acid number is an indicator of carbon's capacity for large, high-molecular-weight natural organic precursors of disinfection by-products in water treatment. The experimental results for removing nitrobenzene, methyl-tert-butyl ether, 4,4-bisphenol, humic acid, and the organic constituents of a biologically treated coking-plant effluent have demonstrated the effectiveness of this capacity-indicator-based method of carbon selection.

  2. Organic carbon transport in the Columbia River

    NASA Astrophysics Data System (ADS)

    Dahm, Clifford N.; Gregory, Stanley V.; Kilho Park, P.

    1981-12-01

    Total organic carbon (TOC) levels in the Columbia River measured monthly from May 1973 to December 1974 ranged from a maximum of 270 μmol l -1 during late spring and early summer to a minimum of 150 μmol l -1 during late autumn. Sampling locations were directly behind the spillway at the Bonneville Dam, 230 km upstream, and at Kalama, Washington, 128km upstream from the river mouth. The average annual TOC contribution from the Columbia River drainage to the north-eastern Pacific is 4·9×10 10 mol with an average concentration of approximately 195μmol l -1. Of this TOC annual export, 89% is dissolved organic carbon (DOC) and 11% is particulate organic carbon (OOC). The TOC and DOC levels were most highly correlated with increased oxygen saturation and dischange, while POC correlated more closely to high instream primary productivy as indicated by higher pH and oxygen supersaturation. Variability of DOC in the main channel of the Columbia River from Portland, Oregon, to the estuary during a June 1974 cruise was minimal. The DOC concentrations ranged from 221-260 μmol l -1 with no significant upstream or downstream gradients. Diel variation also was slight, varying randomly during 24h between 235-257 μmol l -1. The relative annual constancy of the DOC is indicative of the refractory nature of a significant proportion of the dissolved organic load of the Columbia River.

  3. Worldwide organic soil carbon and nitrogen data

    SciTech Connect

    Zinke, P.J.; Stangenberger, A.G.; Post, W.M.; Emanuel, W.R.; Olson, J.S.

    1984-05-01

    A compilation of soil carbon and nitrogen storage data for more than 3500 soil profiles from under natural vegetation or relatively undisturbed sites is presented in this report. A summary table of the carbon and nitrogen storage in a pedon of surface cubic meter for each soil profile, as well as location, elevation, climate, parent material, and vegetation information, are presented. The data were used to determine average carbon and nitrogen storage on land surfaces of the world. Calculations were also made of storage related to climatic classifications, ecosystem clasifications, and latitudinal increments from the equator to 75/sup 0/. Carbon (kg.m/sup -3/) varies from 2 in hot dry climates, through 10 in many cold dry or seasonally moist (warm or hot) climates, to more than 30 in wet alpine or subpolar climates. Nitrogen storage, an order of magnitude smaller than carbon storage in soils, shows broad parallels but exceeds 1600 g.m/sup -3/ for subtropical/tropical premontane or lower montane soils, as well as alpine or subpolar wet soils. Such limiting conditions, defined by a balance of income and loss rates for mature soil profiles, also explain much of the variation among major ecosystem complexes whose soils are partly disturbed, incompletely recovered, or imperfectly known regarding their maturity and stability. Classifying profiles into Holdridge life zones and using appropriate life zone areas, we estimate 1309 x 10/sup 15/ g carbon and 92 x 10/sup 15/ g nitrogen in the world's soils. Alternatively, using average organic carbon and nitrogen densities from one degree latitude bands multiplied by the earth's surface area in the respective bands, we arrive at 1728 x 10/sup 15/ g of carbon and 117 x 10/sup 15/ g of nitrogen. Inadequacies that lead to the disparate estimates are discussed. 123 references, 5 figures, 7 tables.

  4. Factors influencing organic carbon preservation in marine sediments

    NASA Technical Reports Server (NTRS)

    Canfield, D. E.

    1994-01-01

    The organic matter that escapes decomposition is buried and preserved in marine sediments, with much debate as to whether the amount depends on bottom-water O2 concentration. One group argues that decomposition is more efficient with O2, and hence, organic carbon will be preferentially oxidized in its presence, and preserved in its absence. Another group argues that the kinetics of organic matter decomposition are similar in the presence and absence of O2, and there should be no influence of O2 on preservation. A compilation of carbon preservation shows that both groups are right, depending on the circumstances of deposition. At high rates of deposition, such as near continental margins, little difference in preservation is found with varying bottom-water O2. It is important that most carbon in these sediments decomposes by anaerobic pathways regardless of bottom-water O2. Hence, little influence of bottom-water O2 on preservation would, in fact, be expected. As sedimentation rate drops, sediments deposited under oxygenated bottom water become progressively more aerobic, while euxinic sediments remain anaerobic. Under these circumstances, the relative efficiencies of aerobic and anaerobic decomposition could affect preservation. Indeed, enhanced preservation is observed in low-O2 and euxinic environments. To explore in detail the factors contributing to this enhanced carbon preservation, aspects of the biochemistries of the aerobic and anaerobic process are reviewed. Other potential influences on preservation are also explored. Finally, a new model for organic carbon decomposition, the "pseudo-G" model, is developed. This model couples the degradation of refractory organic matter to the overall metabolic activity of the sediment, and has consequences for carbon preservation due to the mixing together of labile and refractory organic matter by bioturbation.

  5. GRANULAR ACTIVATED CARBON ADSORPTION AND INFRARED REACTIVATION: A CASE STUDY

    EPA Science Inventory

    A study evaluated the effectiveness and cost of removing trace organic contaminants and surrogates from drinking water by granular activated carbon (GAC) adsorption. The effect of multiple reactivations of spent GAC was also evaluated. Results indicated that reactivated GAC eff...

  6. Dispersion and separation of nanostructured carbon in organic solvents

    NASA Technical Reports Server (NTRS)

    Landi, Brian J. (Inventor); Raffaelle, Ryne P. (Inventor); Ruf, Herbert J. (Inventor); Evans, Christopher M. (Inventor)

    2011-01-01

    The present invention relates to dispersions of nanostructured carbon in organic solvents containing alkyl amide compounds and/or diamide compounds. The invention also relates to methods of dispersing nanostructured carbon in organic solvents and methods of mobilizing nanostructured carbon. Also disclosed are methods of determining the purity of nanostructured carbon.

  7. Yucca Mountain Area Saturated Zone Dissolved Organic Carbon Isotopic Data

    SciTech Connect

    Thomas, James; Decker, David; Patterson, Gary; Peterman, Zell; Mihevc, Todd; Larsen, Jessica; Hershey, Ronald

    2007-06-25

    Groundwater samples in the Yucca Mountain area were collected for chemical and isotopic analyses and measurements of water temperature, pH, specific conductivity, and alkalinity were obtained at the well or spring at the time of sampling. For this project, groundwater samples were analyzed for major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC). The U.S. Geological Survey (USGS) performed all the fieldwork on this project including measurement of water chemistry field parameters and sample collection. The major ions dissolved in the groundwater, deuterium, oxygen-18, and carbon isotopes of dissolved inorganic carbon (DIC) were analyzed by the USGS. All preparation and processing of samples for DOC carbon isotopic analyses and geochemical modeling were performed by the Desert Research Institute (DRI). Analysis of the DOC carbon dioxide gas produced at DRI to obtain carbon-13 and carbon-14 values was conducted at the University of Arizona Accelerator Facility (a NSHE Yucca Mountain project QA qualified contract facility). The major-ion chemistry, deuterium, oxygen-18, and carbon isotopes of DIC were used in geochemical modeling (NETPATH) to determine groundwater sources, flow paths, mixing, and ages. The carbon isotopes of DOC were used to calculate groundwater ages that are independent of DIC model corrected carbon-14 ages. The DIC model corrected carbon-14 calculated ages were used to evaluate groundwater travel times for mixtures of water including water beneath Yucca Mountain. When possible, groundwater travel times were calculated for groundwater flow from beneath Yucca Mountain to down gradient sample sites. DOC carbon-14 groundwater ages were also calculated for groundwaters in the Yucca Mountain area. When possible, groundwater travel times were estimated for groundwater flow from beneath Yucca Mountain to down gradient groundwater sample sites using the DOC calculated

  8. Black Carbon Contribution to Organic Carbon Stocks in Urban Soil.

    PubMed

    Edmondson, Jill L; Stott, Iain; Potter, Jonathan; Lopez-Capel, Elisa; Manning, David A C; Gaston, Kevin J; Leake, Jonathan R

    2015-07-21

    Soil holds 75% of the total organic carbon (TOC) stock in terrestrial ecosystems. This comprises ecosystem-derived organic carbon (OC) and black carbon (BC), a recalcitrant product of the incomplete combustion of fossil fuels and biomass. Urban topsoils are often enriched in BC from historical emissions of soot and have high TOC concentrations, but the contribution of BC to TOC throughout the urban soil profile, at a regional scale is unknown. We sampled 55 urban soil profiles across the North East of England, a region with a history of coal burning and heavy industry. Through combined elemental and thermogravimetic analyses, we found very large total soil OC stocks (31-65 kg m(-2) to 1 m), exceeding typical values reported for UK woodland soils. BC contributed 28-39% of the TOC stocks, up to 23 kg C m(-2) to 1 m, and was affected by soil texture. The proportional contribution of the BC-rich fraction to TOC increased with soil depth, and was enriched in topsoil under trees when compared to grassland. Our findings establish the importance of urban ecosystems in storing large amounts of OC in soils and that these soils also capture a large proportion of BC particulates emitted within urban areas. PMID:26114917

  9. Photoconductivity of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    Kuriyama, K.; Dresselhaus, M. S.

    1990-08-01

    The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity.

  10. Soil Organic Carbon Loss: An Overlooked Factor in the Carbon Sequestration Potential of Enhanced Mineral Weathering

    NASA Astrophysics Data System (ADS)

    Dietzen, Christiana; Harrison, Robert

    2016-04-01

    Weathering of silicate minerals regulates the global carbon cycle on geologic timescales. Several authors have proposed that applying finely ground silicate minerals to soils, where organic acids would enhance the rate of weathering, could increase carbon uptake and mitigate anthropogenic CO2 emissions. Silicate minerals such as olivine could replace lime, which is commonly used to remediate soil acidification, thereby sequestering CO2 while achieving the same increase in soil pH. However, the effect of adding this material on soil organic matter, the largest terrestrial pool of carbon, has yet to be considered. Microbial biomass and respiration have been observed to increase with decreasing acidity, but it is unclear how long the effect lasts. If the addition of silicate minerals promotes the loss of soil organic carbon through decomposition, it could significantly reduce the efficiency of this process or even create a net carbon source. However, it is possible that this initial flush of microbial activity may be compensated for by additional organic matter inputs to soil pools due to increases in plant productivity under less acidic conditions. This study aimed to examine the effects of olivine amendments on soil CO2 flux. A liming treatment representative of typical agricultural practices was also included for comparison. Samples from two highly acidic soils were split into groups amended with olivine or lime and a control group. These samples were incubated at 22°C and constant soil moisture in jars with airtight septa lids. Gas samples were extracted periodically over the course of 2 months and change in headspace CO2 concentration was determined. The effects of enhanced mineral weathering on soil organic matter have yet to be addressed by those promoting this method of carbon sequestration. This project provides the first data on the potential effects of enhanced mineral weathering in the soil environment on soil organic carbon pools.

  11. Site-Specific Carbon Isotopes in Organics

    NASA Astrophysics Data System (ADS)

    Piasecki, A.; Eiler, J. M.

    2012-12-01

    Natural organic molecules exhibit a wide range of internal site-specific isotope variation (i.e., molecules with same isotopic substitution type but different site). Such variations are generally unconstrained by bulk isotopic measurements. If known, site-specific variations might constrain temperatures of equilibrium, mechanisms of formation or consumption reactions, and possibly other details. For example, lipids can exhibit carbon isotope differences of up to 30‰ between adjacent carbon sites as a result of fractionations arising during decarboxylation of pyruvate and other steps in lipid biosynthesis(1). We present a method for site-specific carbon isotope analysis of propane, based on high-resolution, multi-collector gas source mass spectrometry, using a novel prototype instrument - the Thermo MAT 253 Ultra. This machine has an inlet system and electron bombardment ion source resembling those in conventional stable isotope gas source mass spectrometers, and the energy filter, magnet, and detector array resembling those in multi-collector ICPMS and TIMS. The detector array has 7 detector positions, 6 of which are movable, and each of which can collect ions with either a faraday cup (read through amplifiers ranging from 107-1012 ohms) or an SEM. High mass resolving power (up to 27,000, MRP = M/dM definition) is achieved through a narrow entrance slit, adjustable from 250 to 5 μm. Such resolution can cleanly separate isobaric interferences between isotopologues of organic molecules having the same cardinal mass (e.g., 13CH3 and 12CH2D). We use this technology to analyze the isotopologues and fragments of propane, and use such data to solve for the site-specific carbon isotope fractionation. By measuring isotopologues of both the one-carbon (13CH3) and the two-carbon (13C12CH4) fragment ion, we can solve for both bulk δ13C and the difference in δ13C between the terminal and central carbon position. We tested this method by analyzing mixtures between natural

  12. Epitaxial Approaches to Carbon Nanotube Organization

    NASA Astrophysics Data System (ADS)

    Ismach, Ariel

    Carbon nanotubes have unique electronic, mechanical, optical and thermal properties, which make them ideal candidates as building blocks in nano-electronic and electromechanical systems. However, their organization into well-defined geometries and arrays on surfaces remains a critical challenge for their integration into functional nanosystems. In my PhD, we developed a new approach for the organization of carbon nanotubes directed by crystal surfaces. The principle relies on the guided growth of single-wall carbon nanotubes (SWNTs) by atomic features presented on anisotropic substrates. We identified three different modes of surface-directed growth (or 'nanotube epitaxy'), in which the growth of carbon nanotubes is directed by crystal substrates: We first observed the nanotube unidirectional growth along atomic steps ('ledge-directed epitaxy') and nanofacets ('graphoepitaxy') on the surface of miscut C-plane sapphire and quartz. The orientation along crystallographic directions ('lattice-directed epitaxy') was subsequently observed by other groups on different crystals. We have proposed a "wake growth" mechanism for the nanotube alignment along atomic steps and nanofacets. In this mechanism, the catalyst nanoparticle slides along the step or facet, leaving the nanotube behind as a wake. In addition, we showed that the combination of surface-directed growth with external forces, such as electric-field and gas flow, can lead to the simultaneous formation of complex nanotube structures, such as grids and serpentines. The "wake growth" model, which explained the growth of aligned nanotubes, could not explain the formation of nanotube serpentines. For the latter, we proposed a "falling spaghetti" mechanism, in which the nanotube first grows by a free-standing process, aligned in the direction of the gas flow, then followed by absorption on the stepped surface in an oscillatory manner, due to the competition between the drag force caused by the gas flow on the suspended

  13. Urban Tree Effects on Soil Organic Carbon

    PubMed Central

    Edmondson, Jill L.; O'Sullivan, Odhran S.; Inger, Richard; Potter, Jonathan; McHugh, Nicola; Gaston, Kevin J.; Leake, Jonathan R.

    2014-01-01

    Urban trees sequester carbon into biomass and provide many ecosystem service benefits aboveground leading to worldwide tree planting schemes. Since soils hold ∼75% of ecosystem organic carbon, understanding the effect of urban trees on soil organic carbon (SOC) and soil properties that underpin belowground ecosystem services is vital. We use an observational study to investigate effects of three important tree genera and mixed-species woodlands on soil properties (to 1 m depth) compared to adjacent urban grasslands. Aboveground biomass and belowground ecosystem service provision by urban trees are found not to be directly coupled. Indeed, SOC enhancement relative to urban grasslands is genus-specific being highest under Fraxinus excelsior and Acer spp., but similar to grasslands under Quercus robur and mixed woodland. Tree cover type does not influence soil bulk density or C∶N ratio, properties which indicate the ability of soils to provide regulating ecosystem services such as nutrient cycling and flood mitigation. The trends observed in this study suggest that genus selection is important to maximise long-term SOC storage under urban trees, but emerging threats from genus-specific pathogens must also be considered. PMID:25003872

  14. Urban tree effects on soil organic carbon.

    PubMed

    Edmondson, Jill L; O'Sullivan, Odhran S; Inger, Richard; Potter, Jonathan; McHugh, Nicola; Gaston, Kevin J; Leake, Jonathan R

    2014-01-01

    Urban trees sequester carbon into biomass and provide many ecosystem service benefits aboveground leading to worldwide tree planting schemes. Since soils hold ∼75% of ecosystem organic carbon, understanding the effect of urban trees on soil organic carbon (SOC) and soil properties that underpin belowground ecosystem services is vital. We use an observational study to investigate effects of three important tree genera and mixed-species woodlands on soil properties (to 1 m depth) compared to adjacent urban grasslands. Aboveground biomass and belowground ecosystem service provision by urban trees are found not to be directly coupled. Indeed, SOC enhancement relative to urban grasslands is genus-specific being highest under Fraxinus excelsior and Acer spp., but similar to grasslands under Quercus robur and mixed woodland. Tree cover type does not influence soil bulk density or C∶N ratio, properties which indicate the ability of soils to provide regulating ecosystem services such as nutrient cycling and flood mitigation. The trends observed in this study suggest that genus selection is important to maximise long-term SOC storage under urban trees, but emerging threats from genus-specific pathogens must also be considered. PMID:25003872

  15. Inputs of organic carbon from Ria de Aveiro coastal lagoon to the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Lopes, C. B.; Lillebø, A. I.; Pato, P.; Dias, J. M.; Rodrigues, S. M.; Pereira, E.; Duarte, A. C.

    2008-09-01

    Land/ocean boundaries constitute complex systems with active physical and biogeochemical processes that affect the global carbon cycle. An example of such a system is the mesotidal lagoon named Ria de Aveiro (Portugal, 40°38'N, 08°45'W), which is connected to the Atlantic Ocean by a single channel, 350 m wide. The objective of this study was to estimate the seasonal and inter-tidal variability of organic carbon fluxes between the coastal lagoon and the Ocean, and to assess the contribution of the organic carbon fractions (i.e. dissolved organic carbon (DOC) and particulate organic carbon (POC)) to the export of organic carbon to the Ria de Aveiro plume zone. The organic carbon fractions fluxes were estimated as the product of the appropriate fractional organic carbon concentrations and the water fluxes calculated by a two-dimensional vertically integrated hydrodynamic model (2DH). Results showed that the higher exchanges of DOC and POC fractions at the system cross-section occurred during spring tides but only resulted in a net export of organic carbon in winter, totalling 85 t per tidal cycle. Derived from the winter and summer campaigns, the annual carbon mass balance estimated corresponded to a net export of organic carbon (7957 = 6585 t yr -1 POC + 1372 t yr -1 DOC). On the basis of the spring tidal drainage area, it corresponds to an annual flux of 79 g m -2 of POC and 17 g m -2 of DOC out of the estuary.

  16. Carbon Mineralizability Determines Interactive Effects on Mineralization of Pyrogenic Organic Matter and Soil Organic Carbon

    SciTech Connect

    Whitman, Thea L.; Zhu, Zihua; Lehmann, Johannes C.

    2014-10-31

    Soil organic carbon (SOC) is a critical and active pool in the global C cycle, and the addition of pyrogenic organic matter (PyOM) has been shown to change SOC cycling, increasing or decreasing mineralization rates (often referred to as priming). We adjusted the amount of easily mineralizable C in the soil, through 1-day and 6-month pre-incubations, and in PyOM made from maple wood at 350°C, through extraction. We investigated the impact of these adjustments on C mineralization interactions, excluding pH and nutrient effects and minimizing physical effects. We found short-term increases (+20-30%) in SOC mineralization with PyOM additions in the soil pre-incubated for 6 months. Over the longer term, both the 6-month and 1-day pre-incubated soils experienced net ~10% decreases in SOC mineralization with PyOM additions. This was possibly due to stabilization of SOC on PyOM surfaces, suggested by nanoscale secondary ion mass spectrometry. Additionally, the duration of pre-incubation affected priming interactions, indicating that there may be no optimal pre-incubation time for SOC mineralization studies. We show conclusively that relative mineralizability of SOC in relation to PyOM-24 C is an important determinant of the effect of PyOM additions on SOC mineralization.

  17. Soil organic carbon mining versus priming - controls of soil organic carbon stocks along a management gradient

    NASA Astrophysics Data System (ADS)

    Blanes, M. Carmen; Reinsch, Sabine; Glanville, Helen C.; Jones, Davey L.; Carreira, José A.; Pastrana, David N.; Emmett, Bridget A.

    2015-04-01

    Soil carbon (C), nitrogen (N) and phosphorous (P) are assumed to be connected stoichiometrically and C:N(:P) ratios are frequently used to interpret the soils nutrient status. However, plants are capable of initiating the supply of nutrients by releasing rhizodeposits into the soil, thereby stimulating soil organic matter decomposition mediated by the rhizosphere microbial community. To test the relative importance of the two mechanisms across a fertility gradient in the UK we carried out a laboratory experiment. Intact soil cores from two depths (0-15 cm and 85-100 cm) were incubated and C, N and P were added in all possible combinations resulting in a total of 216 soil cores. Soil respiration was measured (1 h incubation, 10 oC) nine times over a 2 week period. Preliminary results indicate that all soils were C limited at the surface as measured as increased soil CO2 efflux. N additions increased soil respiration only marginally, whereas C+N stimulated microbial activity on the surface, and was even more pronounced in the deeper soil layer. Belowground responses to C+P were small and even smaller for N+P but similar for both soil depths. Our results indicate nutrient controls on soil organic matter turnover differ not only across a management/fertility gradient but also vertically down the soil profile.

  18. Variability of organic and elemental carbon, water soluble organic carbon, and isotopes in Hong Kong

    NASA Astrophysics Data System (ADS)

    Ho, K. F.; Lee, S. C.; Cao, J. J.; Li, Y. S.; Chow, J. C.; Watson, J. G.; Fung, K.

    2006-10-01

    To determine the levels and variations of carbonaceous aerosol in Hong Kong, PM2.5 and PM10 samples were collected by high volume (Hi-vol) samplers at three monitoring stations (representing middle-scale roadside, urban-, and regional-scale environments) during winter (November 2000 to February 2001) and summer (June 2001 to August 2001) periods. The highest concentrations of organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) were found at the middle-scale roadside site with the lowest at the regional-scale site. The percentages of WSOC in total carbon at these sites were inversely correlated with their concentrations (i.e., the highest percentages of WSOC were observed at the regional-scale site). A high WSOC fraction may be associated with aged aerosol because of the secondary formation by photochemical oxidation of organic precursors of anthropogenic pollutants during transport. The annual average of isotope abundances (δ13C) of OC and EC were -26.9±0.5‰ and -25.6±0.1‰, respectively. There were no notable differences for seasonal distributions of carbon isotopic composition, consistent with motor vehicle emissions being the main source contributors of carbonaceous aerosol in Hong Kong. OC 13C abundances at the regional-scale site were higher than those at the middle-scale roadside and urban sites, consistent with secondary organic aerosols of biogenic origin.

  19. Variability of organic and elemental carbon, water soluble organic carbon, and isotopes in Hong Kong

    NASA Astrophysics Data System (ADS)

    Ho, K. F.; Lee, S. C.; Cao, J. J.; Li, Y. S.; Chow, J. C.; Watson, J. G.; Fung, K.

    2006-06-01

    To determine the levels and variations of carbonaceous aerosol in Hong Kong, PM2.5 and PM10 samples were collected by high volume (Hi-vol) samplers at three monitoring stations (representing middle-scale roadside, urban-, and regional-scale environments) during winter (November 2000 to February 2001) and summer (June 2001 to August 2001) periods. The highest concentrations of organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) were found at the middle-scale roadside site with the lowest at the regional-scale site. The percentages of WSOC in total carbon at these sites were inversely correlated with their concentrations (i.e., the highest percentages of WSOC were observed at the regional-scale site). A high WSOC fraction may be associated with aged aerosol because of the secondary formation by photochemical oxidation of organic precursors of anthropogenic pollutants during transport. The annual average of isotope abundances (δ13C) of OC and EC were -26.9±0.5 and -25.6±0.1, respectively. There were no notable differences for seasonal distributions of carbon isotopic composition, consistent with motor vehicle emissions being the main source contributors of carbonaceous aerosol in Hong Kong. OC 13C abundances at the regional-scale site were higher than those at the middle-scale roadside and urban sites, consistent with secondary organic aerosols of biogenic origin.

  20. The importance of a surface organic layer in simulating permafrost thermal and carbon dynamics

    NASA Astrophysics Data System (ADS)

    Jafarov, Elchin; Schaefer, Kevin

    2016-03-01

    Permafrost-affected soils contain twice as much carbon as currently exists in the atmosphere. Studies show that warming of the perennially frozen ground could initiate significant release of the frozen soil carbon into the atmosphere. Initializing the frozen permafrost carbon with the observed soil carbon distribution from the Northern Circumpolar Soil Carbon Database reduces the uncertainty associated with the modeling of the permafrost carbon feedback. To improve permafrost thermal and carbon dynamics we implemented a dynamic surface organic layer with vertical carbon redistribution, and introduced dynamic root growth controlled by active layer thickness, which improved soil carbon exchange between frozen and thawed pools. These changes increased the initial amount of simulated frozen carbon from 313 to 560 Gt C, consistent with observed frozen carbon stocks, and increased the spatial correlation of the simulated and observed distribution of frozen carbon from 0.12 to 0.63.

  1. Carbon nanomaterials: Biologically active fullerene derivatives.

    PubMed

    Bogdanović, Gordana; Djordjević, Aleksandar

    2016-01-01

    Since their discovery, fullerenes, carbon nanotubes, and graphene attract significant attention of researches in various scientific fields including biomedicine. Nano-scale size and a possibility for diverse surface modifications allow carbon nanoallotropes to become an indispensable nanostructured material in nanotechnologies, including nanomedicine. Manipulation of surface chemistry has created diverse populations of water-soluble derivatives of fullerenes, which exhibit different behaviors. Both non-derivatized and derivatized fullerenes show various biological activities. Cellular processes that underline their toxicity are oxidative, genotoxic, and cytotoxic responses.The antioxidant/cytoprotective properties of fullerenes and derivatives have been considered in the prevention of organ oxidative damage and treatment. The same unique physiochemical properties of nanomaterials may also be associated with potential health hazards. Non-biodegradability and toxicity of carbon nanoparticles still remain a great concern in the area of biomedical application. In this review, we report on basic physical and chemical properties of carbon nano-clusters--fullerenes, nanotubes, and grapheme--their specificities, activities, and potential application in biological systems. Special emphasis is given to our most important results obtained in vitro and in vivo using polyhydroxylated fullerene derivative C₆₀(OH)₂₄. PMID:27483572

  2. High rates of organic carbon burial in fjord sediments globally

    NASA Astrophysics Data System (ADS)

    Smith, Richard W.; Bianchi, Thomas S.; Allison, Mead; Savage, Candida; Galy, Valier

    2015-06-01

    The deposition and long-term burial of organic carbon in marine sediments has played a key role in controlling atmospheric O2 and CO2 concentrations over the past 500 million years. Marine carbon burial represents the dominant natural mechanism of long-term organic carbon sequestration. Fjords--deep, glacially carved estuaries at high latitudes--have been hypothesized to be hotspots of organic carbon burial, because they receive high rates of organic material fluxes from the watershed. Here we compile organic carbon concentrations from 573 fjord surface sediment samples and 124 sediment cores from nearly all fjord systems globally. We use sediment organic carbon content and sediment delivery rates to calculate rates of organic carbon burial in fjord systems across the globe. We estimate that about 18 Mt of organic carbon are buried in fjord sediments each year, equivalent to 11% of annual marine carbon burial globally. Per unit area, fjord organic carbon burial rates are one hundred times as large as the global ocean average, and fjord sediments contain twice as much organic carbon as biogenous sediments underlying the upwelling regions of the ocean. We conclude that fjords may play an important role in climate regulation on glacial-interglacial timescales.

  3. Soil organic carbon pools in olive groves of different age

    NASA Astrophysics Data System (ADS)

    Massaccesi, Luisa; De Feudis, Mauro; Nasini, Luigi; Regni, Luca; D'Ascoli, Rosaria; Castaldi, Simona; Proietti, Primo; Agnelli, Alberto

    2016-04-01

    In the last years, the practices which favor the increase of soil organic carbon in the agroecosystem have been widely studied because of their influence on the reduction of atmospheric CO2 (Lal, 1993; Schlesinger, 2000). The accumulation of the organic carbon into the soil depends to a great extent upon climate and pedological properties (Burke et al., 1989; Miller et al., 1994), although in the agricultural soils the cultivation system also plays a key role. The olive grove might potentially represent a relevant land use to improve C sequestration in soil, but there are few data available to support this hypothesis. In a study site located in central Italy (Deruta, PG), we analyzed the soil organic carbon (SOC) pools in two olive groves of different age (7 and 30 years) and, as control, in a site adjacent to the groves cropped with cereals for at least 30 years. With the aim to isolate and quantify the active, intermediate and passive functional SOC pools in the olive groves and in the control, we used a combined physical and chemical fractionation method (Zimmermann et al., 2007). The main results shown that the total organic carbon content in the Ap horizons was the highest in the 30-years-old olive grove, followed by the 7-years-old olive grove, and then by the control soil. The content of active C, in form of particulate organic matter (POM) and water soluble organic matter (WEOM), was greater in the olive grove compared to the control soil and increase with the age of the grove. About the amount of C in the intermediate and passive pools, no significant differences were found among the olive groves and the control. These preliminary results indicated that the greater total organic C content occurred in the 30-year-old olive grove with respect to the 7-years-old grove and the control, has to be ascribed to the greater content of active organic matter (POM and WEOM), and not to the accumulation in soil of organic C in a more stabilised form.

  4. Cyanobacterial reuse of extracellular organic carbon in microbial mats.

    PubMed

    Stuart, Rhona K; Mayali, Xavier; Lee, Jackson Z; Craig Everroad, R; Hwang, Mona; Bebout, Brad M; Weber, Peter K; Pett-Ridge, Jennifer; Thelen, Michael P

    2016-05-01

    Cyanobacterial organic matter excretion is crucial to carbon cycling in many microbial communities, but the nature and bioavailability of this C depend on unknown physiological functions. Cyanobacteria-dominated hypersaline laminated mats are a useful model ecosystem for the study of C flow in complex communities, as they use photosynthesis to sustain a more or less closed system. Although such mats have a large C reservoir in the extracellular polymeric substances (EPSs), the production and degradation of organic carbon is not well defined. To identify extracellular processes in cyanobacterial mats, we examined mats collected from Elkhorn Slough (ES) at Monterey Bay, California, for glycosyl and protein composition of the EPS. We found a prevalence of simple glucose polysaccharides containing either α or β (1,4) linkages, indicating distinct sources of glucose with differing enzymatic accessibility. Using proteomics, we identified cyanobacterial extracellular enzymes, and also detected activities that indicate a capacity for EPS degradation. In a less complex system, we characterized the EPS of a cyanobacterial isolate from ES, ESFC-1, and found the extracellular composition of biofilms produced by this unicyanobacterial culture were similar to that of natural mats. By tracing isotopically labeled EPS into single cells of ESFC-1, we demonstrated rapid incorporation of extracellular-derived carbon. Taken together, these results indicate cyanobacteria reuse excess organic carbon, constituting a dynamic pool of extracellular resources in these mats. PMID:26495994

  5. Activated, coal-based carbon foam

    DOEpatents

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2004-12-21

    An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

  6. Activated, coal-based carbon foam

    SciTech Connect

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2009-06-09

    An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

  7. A combined process of activated carbon adsorption, ion exchange resin treatment and membrane concentration for recovery of dissolved organics in pre-hydrolysis liquor of the kraft-based dissolving pulp production process.

    PubMed

    Shen, Jing; Kaur, Ishneet; Baktash, Mir Mojtaba; He, Zhibin; Ni, Yonghao

    2013-01-01

    To recover dissolved organics in pre-hydrolysis liquor (PHL) of the kraft-based dissolving pulp production process, a new combined process concept of sequential steps of activated carbon adsorption, ion exchange resin treatment, and membrane concentration, was proposed. The removal of lignin in the PHL was achieved in the activated carbon adsorption step, which also facilitates the subsequent operations, such as the membrane filtration and ion exchange resin treatment. The ion exchange resin treatment resulted in the removal/concentration of acetic acid, which opens the door for acetic acid recovery. The membrane filtration is to recover/concentrate the dissolved sugars. The combined process resulted in the production of PHL-based concentrate with relatively high concentration of hemicellulosic sugars, i.e., 22.13%. PMID:23131623

  8. Fossil organic carbon in Siberian Yedoma and thermokarst deposits

    NASA Astrophysics Data System (ADS)

    Strauss, J.; Schirrmeister, L.; Wetterich, S.

    2011-12-01

    carbon inventory as reflected by the biomarker results. We conclude that Yedoma with its degradation features at Duvanny Yar and Buor Khaya contain an organic-carbon inventory which is lower than in other published Yedoma profiles. Nevertheless, these deposits contain a significant carbon pool because of low OM decomposition rates and for this reason a potential high risk for its activation and release under warming conditions.

  9. Design of activated carbon/activated carbon asymmetric capacitors

    NASA Astrophysics Data System (ADS)

    Piñeiro-Prado, Isabel; Salinas-Torres, David; Ruiz Rosas, Ramiro; Morallon, Emilia; Cazorla-Amoros, Diego

    2016-03-01

    Supercapacitors are energy storage devices that offer a high power density and a low energy density in comparison with batteries. Their limited energy density can be overcome by using asymmetric configuration in mass electrodes, where each electrode works within their maximum available potential window, rendering the maximum voltage output of the system. Such asymmetric capacitors must be optimized through careful electrochemical characterization of the electrodes for accurate determination of the capacitance and the potential stability limits. The results of the characterization are then used for optimizing mass ratio of the electrodes from the balance of stored charge. The reliability of the design largely depends on the approach taken for the electrochemical characterization. Therefore, the performance could be lower than expected and even the system could break down, if a well thought out procedure is not followed. In this work, a procedure for the development of asymmetric supercapacitors based on activated carbons is detailed. Three activated carbon materials with different textural properties and surface chemistry have been systematically characterized in neutral aqueous electrolyte. The asymmetric configuration of the masses of both electrodes in the supercapacitor has allowed to cover a higher potential window, resulting in an increase of the energy density of the three devices studied when compared with the symmetric systems, and an improved cycle life.

  10. Storage of Organic and Inorganic Carbon in Human Settlements

    NASA Astrophysics Data System (ADS)

    Churkina, G.

    2009-12-01

    It has been shown that urban areas have carbon density comparable with tropical forest. Carbon density of urban areas may be even higher, because the density of organic carbon only was taking into account. Human settlements store carbon in two forms such as organic and inorganic. Carbon is stored in organic form in living biomass such as trees, grasses or in artifacts derived from biomass such as wooden furniture, building structures, paper, clothes and shoes made from natural materials. Inorganic carbon or fossil carbon, meanwhile, is primarily stored in objects fabricated by people like concrete, plastic, asphalt, and bricks. The key difference between organic and inorganic forms of carbon is how they return to the gaseous state. Organic carbon can be returned to the atmosphere without applying additional artificial energy through decomposition of organic matter, whereas energy input such as burning is needed to release inorganic carbon. In this study I compare inorganic with organic carbon storage, discuss their carbon residence time, decomposition rates, and possible implications for carbon emissions.

  11. OCoc- from Ocean Colour to Organic Carbon

    NASA Astrophysics Data System (ADS)

    Heim, B.; Overduin, P. P.; Schirrmeister, L.; Lantuit, H.; Doerffer, R.

    2009-12-01

    Enhanced permafrost warming and increased arctic river discharges have heightened concern about the input of terrigenous matter into Arctic coastal waters. The ‘OCoc-from Ocean Colour to Organic Carbon’ project (IPY-project 1176), funded by the German Research Foundation (DFG), is an Ocean Colour study joined with the Arctic Coastal Dynamics ACD network and Arctic Circum-polar Coastal Observatory Network ACCO-Net (IPY-project 90). OCoc uses Ocean Colour satellite data for synoptical monitoring of organic matter fluxes from fluvial and coastal sources. Initial results from German-Russian expeditions at the southeastern Laptev Sea Coast (Arctic Siberia, Russia) in August 2008 and August 2009 are presented. Large parts of this coastal zone are characterized by highly erosive organic-rich material. Ocean Colour MERIS Reduced Resolution (RR)-LIB data of the have been processed towards optical aquatic parameters using Beam-Visat4.2 and the MERIS case2 regional processor for coastal application (C2R). Calculated aquatic parameters are absorption and backscattering coefficients, apparent optical properties such as the first attenuation depth (‘Z90’) and calculated concentrations of chlorophyll, total suspended matter and coloured dissolved organic matter absorption from the water leaving reflectances. Initial comparisons with expedition data (Secchi depths, cDOM) show that the MERIS-C2R optical parameters ’total absorption’ and the first attenuation depth, ’Z90’, seem adequately to represent true conditions. High attenuation values in the spectral blue wavelength range may serve as tracer for the organic-rich terrigenous input. The synoptic information of Ocean Colour products will provide valuable spatial and dynamical information on the Organic Carbon and sediment fluxes from the Siberian permafrost coast.

  12. Fate of Organic Micropollutants during Hydrothermal Carbonization

    NASA Astrophysics Data System (ADS)

    Weiner, B.; Baskyr, I.; Pörschmann, J.; Kopinke, F.-D.

    2012-04-01

    The hydrothermal carbonization (HTC) is an exothermic process, in which biomass in an aqueous suspension is transformed into a bituminous coal-like material (hydrochar) at temperatures between 180-250°C and under moderate pressure. With these process conditions, little gas is generated (1-5%), and a fraction of the organic carbon is dissolved in the aqueous phase (10-30%) but the largest part is obtained as solid char. The respective yields and the molecular composition depend on the choice of educts and the process conditions, such as temperature, pH-value, and reaction time. Various biomass-educts have recently been studied, such as waste materials from agriculture, brewer's spent grains, sewage sludge, as well as wood and paper materials. Besides their use for energy generation, the hydrochars have also been investigated as soil amendments. Prior to addition of the chars to soil, these should be free of toxic components that could be released into the environment as harmful organic pollutants. Herein, the potential for the degradation of trace organic pollutants, such as pesticides and pharmaceuticals, under typical HTC conditions will be presented. The degradation of selected organic pollutants with different polarity and hydrophobicity was investigated. Scope and limitations of the degradation potential of the HTC are discussed on examples of micro pollutants such as hormones, residues of pharmaceuticals and personal care products including their metabolites, and pesticides. We will show that the target analytes are partially and in some cases completely degraded. The degree of degradation depends on the HTC process conditions such as reaction temperature and time, the solution pH value, the presence of catalysts or additional reagents. The biotic and abiotic degradation of chlorinated organic compounds, in particular chlorinated aromatics, has been a well-known environmental problem and remains a challenging issue for the development of a HTC process for

  13. Dissolved organic carbon in rainwater: Glassware decontamination and sample preservation and volatile organic carbon

    NASA Astrophysics Data System (ADS)

    Campos, M. L. A. M.; Nogueira, R. F. P.; Dametto, P. R.; Francisco, J. G.; Coelho, C. H.

    The efficiency of different methods for the decontamination of glassware used for the analysis of dissolved organic carbon (DOC) was tested using reported procedures as well as new ones proposed in this work. A Fenton solution bath (1.0 mmol L -1 Fe 2+ and 100 mmol L -1 H 2O 2) for 1 h or for 30 min employing UV irradiation showed to combine simplicity, low cost and high efficiency. Using the optimized cleaning procedure, the DOC for stored UV-irradiated ultra-pure water reached concentrations below the limit of detection (0.19 μmol C L -1). Filtered (0.7 μm) rain samples maintained the DOC integrity for at least 7 days when stored at 4 °C. The volatile organic carbon (VOC) fraction in the rain samples collected at two sites in São Paulo state (Brazil) ranged from 0% to 56% of their total DOC content. Although these high-VOC concentrations may be derived from the large use of ethanol fuel in Brazil, our results showed that when using the high-temperature catalytic oxidation technique, it is essential to measure DOC rather than non-purgeble organic carbon to estimate organic carbon, since rainwater composition can be quite variable, both geographically and temporally.

  14. Elevated dissolved organic carbon biodegradability from thawing and collapsing permafrost

    NASA Astrophysics Data System (ADS)

    Abbott, Benjamin W.; Larouche, Julia R.; Jones, Jeremy B.; Bowden, William B.; Balser, Andrew W.

    2014-10-01

    As high latitudes warm, a portion of the large organic carbon pool stored in permafrost will become available for transport to aquatic ecosystems as dissolved organic carbon (DOC). If permafrost DOC is biodegradable, much will be mineralized to the atmosphere in freshwater systems before reaching the ocean, accelerating carbon transfer from permafrost to the atmosphere, whereas if recalcitrant, it will reach marine ecosystems where it may persist over long time periods. We measured biodegradable DOC (BDOC) in water flowing from collapsing permafrost (thermokarst) on the North Slope of Alaska and tested the role of DOC chemical composition and nutrient concentration in determining biodegradability. DOC from collapsing permafrost was some of the most biodegradable reported in natural systems. However, elevated BDOC only persisted during active permafrost degradation, with a return to predisturbance levels once thermokarst features stabilized. Biodegradability was correlated with background nutrient concentration, but nutrient addition did not increase overall BDOC, suggesting that chemical composition may be a more important control on DOC processing. Despite its high biodegradability, permafrost DOC showed evidence of substantial previous microbial processing, and we present four hypotheses explaining this incongruity. Because thermokarst features form preferentially on river banks and lake shores and can remain active for decades, thermokarst may be the dominant short-term mechanism delivering sediment, nutrients, and biodegradable organic matter to aquatic systems as the Arctic warms.

  15. Mercury binding on activated carbon

    SciTech Connect

    Bihter Padak; Michael Brunetti; Amanda Lewis; Jennifer Wilcox

    2006-11-15

    Density functional theory has been employed for the modeling of activated carbon (AC) using a fused-benzene ring cluster approach. Oxygen functional groups have been investigated for their promotion of effective elemental mercury binding on AC surface sites. Lactone and carbonyl functional groups yield the highest mercury binding energies. Further, the addition of halogen atoms has been considered to the modeled surface, and has been found to increase the AC's mercury adsorption capacity. The mercury binding energies increase with the addition of the following halogen atoms, F {gt} Cl {gt} Br {gt} I, with the fluorine addition being the most promising halogen for increasing mercury adsorption.

  16. Organic carbon-14 in the Amazon River system

    SciTech Connect

    Hedges, J.I.; Ertel, J.R.; Quay, P.D.; Grootes, P.M.; Richey, J.E.; Devol, A.H.; Farwell, G.W.; Schmidt, F.W.; Salati, E.

    1986-03-07

    Coarse and fine suspended particulate organic materials and dissolved humic and fulvic acids transported by the Amazon River all contain bomb-produced carbon-14, indicating relatively rapid turnover of the parent carbon pools. However, the carbon-14 contents of these coexisting carbon forms are measurably different and may reflect varying degrees of retention by soils in the drainage basin. 20 references, 1 table.

  17. 28 CFR 551.34 - Organization activities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Organization activities. 551.34 Section... MISCELLANEOUS Inmate Organizations § 551.34 Organization activities. (a) An officer of the inmate organization... organization; (2) Nature or purpose of the activity; (3) Date, time, and estimated duration of the activity;...

  18. CONSIDERATIONS IN GRANULAR ACTIVATED CARBON TREATMENT OF COMBINED INDUSTRIAL WASTEWATERS

    EPA Science Inventory

    The objective of this project was to examine the use of activated carbon in reducing the content of biologically resistant organic compounds in a combined industrial wastewater treatment system. The invvestigation was conducted in two stages: (1) characterize organic priority pol...

  19. Three powerful dinuclear metal-organic catalysts for converting CO2 into organic carbonates.

    PubMed

    Zhao, Dan; Liu, Xiao-Hui; Shi, Zhuang-Zhi; Zhu, Chen-Dan; Zhao, Yue; Wang, Peng; Sun, Wei-Yin

    2016-09-28

    Developing efficient catalysts for converting carbon dioxide (CO2) into varied organic carbonates is an important scientific goal. By using the NH2-functionalized tripodal ligand 2-((bis(2-aminoethyl)amino)methyl)phenol (HL), three dinuclear metal-organic complexes [Zn(L)]2·2ClO4 (1), [Cu(L)]2·2ClO4·2H2O (2) and [Cd(L)]2·2ClO4 (3) have been successfully isolated and structurally characterized using single-crystal X-ray diffraction analyses. Considering the dinuclear metal centers and the NH2-functional groups in the structures, 1-3 were investigated as catalysts for converting CO2 into organic carbonates, and the results show that 1-3 exhibit an outstanding ability for converting CO2 into varied organic carbonates at atmospheric pressure (0.1 MPa). The catalytic system also displays a wide substrate scope and high catalytic activity, and the reaction mechanism has been proposed herein. PMID:27530724

  20. Selective stabilization of aliphatic organic carbon by iron oxide

    PubMed Central

    Adhikari, Dinesh; Yang, Yu

    2015-01-01

    Stabilization of organic matter in soil is important for natural ecosystem to sequestrate carbon and mitigate greenhouse gas emission. It is largely unknown what factors govern the preservation of organic carbon in soil, casting shadow on predicting the response of soil to climate change. Iron oxide was suggested as an important mineral preserving soil organic carbon. However, ferric minerals are subject to reduction, potentially releasing iron and decreasing the stability of iron-bound organic carbon. Information about the stability of iron-bound organic carbon in the redox reaction is limited. Herein, we investigated the sorptive interactions of organic matter with hematite and reductive release of hematite-bound organic matter. Impacts of organic matter composition and conformation on its sorption by hematite and release during the reduction reaction were analyzed. We found that hematite-bound aliphatic carbon was more resistant to reduction release, although hematite preferred to sorb more aromatic carbon. Resistance to reductive release represents a new mechanism that aliphatic soil organic matter was stabilized by association with iron oxide. Selective stabilization of aliphatic over aromatic carbon can greatly contribute to the widely observed accumulation of aliphatic carbon in soil, which cannot be explained by sorptive interactions between minerals and organic matter. PMID:26061259

  1. Carbon uptake in low dissolved inorganic carbon environments: the effect of limited carbon availability on photosynthetic organisms in thermal waters

    NASA Astrophysics Data System (ADS)

    Myers, K. D.; Omelon, C. R.; Bennett, P.

    2010-12-01

    Photosynthesis is the primary carbon fixation process in thermal waters below 70°C, but some hydrothermal waters have extremely low dissolved inorganic carbon (DIC), potentially limiting the growth of inorganic carbon fixing organisms such as algae and cyanobacteria. To address the issue of how carbon is assimilated by phototrophs in these environments, we conducted experiments to compare inorganic carbon uptake mechanisms by two phylogenetically distinct organisms collected from geographically distinct carbon limited systems: the neutral pH geothermal waters of El Tatio, Chile, and the acidic geothermal waters of Tantalus Creek in Norris Geyser Basin, Yellowstone National Park. Discharge waters at El Tatio have low total DIC concentrations (2 to 6 ppm) found mainly as HCO3-; this is in contrast to even lower measured DIC values in Tantalus Creek (as low as 0.13 ppm) that, due to a measured pH of 2.5, exists primarily as CO2. Cyanobacteria and algae are innately physiologically plastic, and we are looking to explore the possibility that carbon limitation in these environments is extreme enough to challenge that plasticity and lead to a suite of carbon uptake adaptations. We hypothesize that these microorganisms utilize adaptive modes of Ci uptake that allow them to survive under these limiting conditions. Cyanobacteria (primarily Synechococcus spp.) isolated from El Tatio can utilize either passive CO2 uptake or active HCO3- uptake mechanisms, in contrast to the eukaryotic alga Cyanidium spp. from Tantalus Creek, which is restricted to an energy-dependent CO2 uptake mechanism. To test this hypothesis, we conducted pH drift experiments (Omelon et al., 2008) to examine changes in pH and [DIC] under a range of pH and [DIC] culture conditions. This work provides baseline information upon which we will begin to investigate the effects of low [DIC] on the growth of phototrophs collected from these and other less carbon limited systems.

  2. Soil Organic Carbon Degradation, Barrow, 2013-2014

    DOE Data Explorer

    Gu, Baohua; Yang, Ziming

    2015-03-30

    This dataset provides information about soil organic carbon decomposition in Barrow soil incubation studies. The soil cores were collected from low-center polygon (Area A) and were incubated in the laboratory at different temperatures for up to 60 days. Transformations of soil organic carbon were characterized by UV and FT-IR, and small organic acids in water-soluble carbons were quantified by ion chromatography during the incubation

  3. Comparison of carbon onions and carbon blacks as conductive additives for carbon supercapacitors in organic electrolytes

    NASA Astrophysics Data System (ADS)

    Jäckel, N.; Weingarth, D.; Zeiger, M.; Aslan, M.; Grobelsek, I.; Presser, V.

    2014-12-01

    This study investigates carbon onions (∼400 m2 g-1) as a conductive additive for supercapacitor electrodes of activated carbon and compares their performance with carbon black with high or low internal surface area. We provide a study of the electrical conductivity and electrochemical behavior between 2.5 and 20 mass% addition of each of these three additives to activated carbon. Structural characterization shows that the density of the resulting film electrodes depends on the degree of agglomeration and the amount of additive. Addition of low surface area carbon black (∼80 m2 g-1) enhances the power handling of carbon electrodes but significantly lowers the specific capacitance even when adding small amounts of carbon black. A much lower decrease in specific capacitance is observed for carbon onions and the best values are seen for carbon black with a high surface area (∼1390 m2 g-1). The overall performance benefits from the addition of any of the studied additives only at either high scan rates and/or electrolytes with high ion mobility. Normalization to the volume shows a severe decrease in volumetric capacitance and only at high current densities nearing 10 A g-1 we can see an improvement of the electrode capacitance.

  4. Input related microbial carbon dynamic of soil organic matter in particle size fractions

    NASA Astrophysics Data System (ADS)

    Gude, A.; Kandeler, E.; Gleixner, G.

    2012-04-01

    This paper investigated the flow of carbon into different groups of soil microorganisms isolated from different particle size fractions. Two agricultural sites of contrasting organic matter input were compared. Both soils had been submitted to vegetation change from C3 (Rye/Wheat) to C4 (Maize) plants, 25 and 45 years ago. Soil carbon was separated into one fast-degrading particulate organic matter fraction (POM) and one slow-degrading organo-mineral fraction (OMF). The structure of the soil microbial community were investigated using phospholipid fatty acids (PLFA), and turnover of single PLFAs was calculated from the changes in their 13C content. Soil enzyme activities involved in the degradation of carbohydrates was determined using fluorogenic MUF (methyl-umbelliferryl phosphate) substrates. We found that fresh organic matter input drives soil organic matter dynamic. Higher annual input of fresh organic matter resulted in a higher amount of fungal biomass in the POM-fraction and shorter mean residence times. Fungal activity therefore seems essential for the decomposition and incorporation of organic matter input into the soil. As a consequence, limited litter input changed especially the fungal community favouring arbuscular mycorrhizal fungi. Altogether, supply and availability of fresh plant carbon changed the distribution of microbial biomass, the microbial community structure and enzyme activities and resulted in different priming of soil organic matter. Most interestingly we found that only at low input the OMF fraction had significantly higher calculated MRT for Gram-positive and Gram-negative bacteria suggesting high recycling of soil carbon or the use of other carbon sources. But on average all microbial groups had nearly similar carbon uptake rates in all fractions and both soils, which contrasted the turnover times of bulk carbon. Hereby the microbial carbon turnover was always faster than the soil organic carbon turnover and higher carbon input

  5. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyan, M.; Lafferty, C.; Kimber, G.

    1996-10-01

    This work describes development of a series of novel activated carbon materials and their testing for possible water treatment applications by studying the adsorption of sodium pentachlorphenolate, PCP (a common herbicide/wood preservative). Although the application of activated carbons is an established technology for the treatment of public water supplies, there is a growing need for materials with higher selectivity and adsorptive capacities as well as high abrasion resistance. The materials that will be discussed include extruded wood-derived carbons with novel pore size distributions and high hardness, as well as activated carbon fiber composites. Comparisons will be made with commercial granular water treatment carbons.

  6. Phylogenetic organization of bacterial activity.

    PubMed

    Morrissey, Ember M; Mau, Rebecca L; Schwartz, Egbert; Caporaso, J Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J; Liu, Cindy M; Hayer, Michaela; McHugh, Theresa A; Marks, Jane C; Price, Lance B; Hungate, Bruce A

    2016-09-01

    Phylogeny is an ecologically meaningful way to classify plants and animals, as closely related taxa frequently have similar ecological characteristics, functional traits and effects on ecosystem processes. For bacteria, however, phylogeny has been argued to be an unreliable indicator of an organism's ecology owing to evolutionary processes more common to microbes such as gene loss and lateral gene transfer, as well as convergent evolution. Here we use advanced stable isotope probing with (13)C and (18)O to show that evolutionary history has ecological significance for in situ bacterial activity. Phylogenetic organization in the activity of bacteria sets the stage for characterizing the functional attributes of bacterial taxonomic groups. Connecting identity with function in this way will allow scientists to begin building a mechanistic understanding of how bacterial community composition regulates critical ecosystem functions. PMID:26943624

  7. Phylogenetic organization of bacterial activity

    PubMed Central

    Morrissey, Ember M; Mau, Rebecca L; Schwartz, Egbert; Caporaso, J Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J; Liu, Cindy M; Hayer, Michaela; McHugh, Theresa A; Marks, Jane C; Price, Lance B; Hungate, Bruce A

    2016-01-01

    Phylogeny is an ecologically meaningful way to classify plants and animals, as closely related taxa frequently have similar ecological characteristics, functional traits and effects on ecosystem processes. For bacteria, however, phylogeny has been argued to be an unreliable indicator of an organism's ecology owing to evolutionary processes more common to microbes such as gene loss and lateral gene transfer, as well as convergent evolution. Here we use advanced stable isotope probing with 13C and 18O to show that evolutionary history has ecological significance for in situ bacterial activity. Phylogenetic organization in the activity of bacteria sets the stage for characterizing the functional attributes of bacterial taxonomic groups. Connecting identity with function in this way will allow scientists to begin building a mechanistic understanding of how bacterial community composition regulates critical ecosystem functions. PMID:26943624

  8. Organic carbon accumulation capability of two typical tidal wetland soils in Chongming Dongtan, China.

    PubMed

    Zhang, Shiping; Wang, Lei; Hu, Jiajun; Zhang, Wenquan; Fu, Xiaohua; Le, Yiquan; Jin, Fangming

    2011-01-01

    We measured organic carbon input and content of soil in two wetland areas of Chongming Dongtan (Yangtze River Estuary) to evaluate variability in organic carbon accumulation capability in different wetland soils. Observed differences were investigated based on the microbial activity and environmental factors of the soil at the two sites. Results showed that the organic carbon content of wetland soil vegetated with Phragmites australis (site A) was markedly lower than that with P. australis and Spartina alterniflora (site B). Sites differences were due to higher microbial activity at site A, which led to higher soil respiration intensity and greater carbon outputs. This indicated that the capability of organic carbon accumulation of the site B soils was greater than at site A. In addition, petroleum pollution and soil salinity were different in the two wetland soils. After bio-remediation, the soil petroleum pollution at site B was reduced to a similar level of site A. However, the culturable microbial biomass and enzyme activity in the remediated soils were also lower than at site A. These results indicated that greater petroleum pollution at site B did not markedly inhibit soil microbial activity. Therefore, differences in vegetation type and soil salinity were the primary factors responsible for the variation in microbial activity, organic carbon output and organic carbon accumulation capability between site A and site B. PMID:21476345

  9. [Organic Carbon and Elemental Carbon in Forest Biomass Burning Smoke].

    PubMed

    Huang, Ke; Liu, Gang; Zhou, Li-min; Li, Jiu-hai; Xu, Hui; Wu, Dan; Hong, Lei; Chen, Hui-yu; Yang, Wei-zong

    2015-06-01

    Ten kinds of trees were selected for preparing dry and wet stick samples. Concentrations of organic carbon (OC), elemental carbon (EC) in particular matter produced by sticks samples in the flaming and smoldering were analyzed through the Thermal Optical Carbon Analyzer (Model 2001A). The results showed that mean values of OC (EF(OC)), EC (EF(EC)), PM (EF(PM)) emission factors were 6.8, 2.1, 16.5 g x kg(-1) in the dry stick flaming smoke, 57.5, 11.1, 130.9 g x kg(-1) in the dry stick smoldering smoke, 13.6, 3.3, 30.5 g x kg(-1) in the wet stick flaming smoke, 57.6, 9.6, 125.6 g x kg(-1) in the wet stick smoldering smoke. Compared to the flaming condition, EF(OC), EF(EC), EF(PM), were much higher in the smoldering condition. In the flaming condition, EF(OC), EF(EC), EF(PM) had positive correlations with the moisture content. The mean values of OC/PM, EC/PM, TC/PM (TC = OC + EC) were 45%, 10%, 55%, and the mass fractions of OC was much higher in smoldering condition than those in flaming condition, but the mass fractions of EC was lower in the smoldering condition. Compared to dry sticks, the smoke of wet sticks combustion had higher mass fractions of OC and lower mass fractions of EC. The mean value of OC/EC was 3.3 (2.5-5.2) in the dry stick flaming smoke, and was 5.2 (4.3-6.3) in the dry stick smoldering smoke, in the wet stick flaming smoke was 4.1 (3.1-5.3), and was 6.2 (4.2-8.4) in the wet stick smoldering smoke. Compared to the flaming condition, the mean value of OC/EC was higher in the smoldering condition, and the mean value of OC/EC was much higher in high moisture content stick combustion smoke. The correlation coefficient between OC and EC was 0.985 in dry stick combustions, and was 0.915 in wet stick combustions. So, based on the flaming and smoldering condition, the correlation between OC and EC was significant in different moisture contents of sticks. PMID:26387300

  10. Carbon-catalyzed gasification of organic feedstocks in supercritical water

    SciTech Connect

    Xu, X.; Matsumura, Y.; Stenberg, J.; Antal, M.J. Jr.

    1996-08-01

    Spruce wood charcoal, macadamia shell charcoal, coal activated carbon, and coconut shell activated carbon catalyze the gasification of organic compounds in supercritical water. Feedstocks studied in this paper include glycerol, glucose, cellobiose, whole biomass feedstocks (depithed bagasse liquid extract and sewage sludge), and representative Department of Defense (DoD) wastes (methanol, methyl ethyl ketone, ethylene glycol, acetic acid, and phenol). The effects of temperature, pressure, reactant concentration, weight hourly space velocity, and the type of catalyst on the gasification of glucose are reported. Complete conversion of glucose (22% by weight in water) to a hydrogen-rich synthesis gas was realized at a weight hourly space velocity (WHSV) of 22.2 h{sup {minus}1} in supercritical water at 600 C, 34.5 MPa. Complete conversions of the whole biomass feeds were also achieved at the same temperature and pressure. The destruction efficiencies for the representative DoD wastes were also high. Deactivation of the carbon catalyst was observed after 4 h of operation without swirl in the entrance region of the reactor, but the carbon gasification efficiency remained near 100% for more than 6 h when a swirl generator was employed in the entrance of the reactor.

  11. Transient Dissolved Organic Carbon Through Soils

    NASA Astrophysics Data System (ADS)

    Mei, Y.; Hornberger, G. M.; Kaplan, L. A.; Newbold, J. D.; Aufdenkampe, A. K.; Tsang, Y.

    2009-12-01

    Dissolved organic carbon (DOC) is an important constituent of soil solution that plays a role in many chemical and biological processes in soils; it is also an important energy source for bacteria in the soil ecosystem. Hydrology has a significant control on the transport and fate of dissolved organic carbon in the soil but mechanisms that affect said transport are not well understood. In particular, dynamic information on DOC transport through forest soils on short time scales (one or two precipitation event) is lacking at present. DOC is a very complex mix of organic compounds. A key to quantifying DOC dynamics is to establish useful approximations for behavior of this complex mixture. Biodegradable dissolved organic carbon (BDOC) is an important part of DOC. It is reported that between 12 and 44% of DOC released from the forest floor can be decomposed in solutions by indigenous microbes. In our study, we considered how DOC, BDOC, and flow interact in soil columns. In-situ soil cores with two different lengths were installed under a mixed deciduous canopy. The effects of artificial rain on DOC and BDOC transport were examined by dripping nano pure water amended with bromide on the top of soil cores and sampling the water collected at the bottom of the cores for DOC and BDOC. We used plug-flow biofilm reactors to measure the BDOC concentration. It is likely that reduced rates of decomposition in dry soils will cause microbial products of DOC to accumulate; hence DOC concentration should be high at the first flush of rain and decline as the event proceeds. The experimental results show the expected pattern, that is, the first samples we collected always had the highest DOC and BDOC concentrations. The concentrations tend to decline through the simulated precipitation event. Application of a second “storm” forty minutes after the cessation of the first application of water resulted in effluent DOC concentration increasing a small amount initially and then

  12. Temperature Dependence of Photodegradation of Dissolved Organic Matter to Dissolved Inorganic Carbon and Particulate Organic Carbon

    PubMed Central

    Porcal, Petr; Dillon, Peter J.; Molot, Lewis A.

    2015-01-01

    Photochemical transformation of dissolved organic matter (DOM) has been studied for more than two decades. Usually, laboratory or “in-situ” experiments are used to determine photodegradation variables. A common problem with these experiments is that the photodegradation experiments are done at higher than ambient temperature. Five laboratory experiments were done to determine the effect of temperature on photochemical degradation of DOM. Experimental results showed strong dependence of photodegradation on temperature. Mathematical modeling of processes revealed that two different pathways engaged in photochemical transformation of DOM to dissolved inorganic carbon (DIC) strongly depend on temperature. Direct oxidation of DOM to DIC dominated at low temperatures while conversion of DOM to intermediate particulate organic carbon (POC) prior to oxidation to DIC dominated at high temperatures. It is necessary to consider this strong dependence when the results of laboratory experiments are interpreted in regard to natural processes. Photodegradation experiments done at higher than ambient temperature will necessitate correction of rate constants. PMID:26106898

  13. SORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBONS

    EPA Science Inventory

    The mechanisms and rate of elemental mercury (HgO) capture by activated carbons have been studied using a bench-scale apparatus. Three types of activated carbons, two of which are thermally activated (PC-100 and FGD) and one with elemental sulfur (S) impregnated in it (HGR), were...

  14. Statistics provide guidance for indigenous organic carbon detection on Mars missions.

    PubMed

    Sephton, Mark A; Carter, Jonathan N

    2014-08-01

    Data from the Viking and Mars Science Laboratory missions indicate the presence of organic compounds that are not definitively martian in origin. Both contamination and confounding mineralogies have been suggested as alternatives to indigenous organic carbon. Intuitive thought suggests that we are repeatedly obtaining data that confirms the same level of uncertainty. Bayesian statistics may suggest otherwise. If an organic detection method has a true positive to false positive ratio greater than one, then repeated organic matter detection progressively increases the probability of indigeneity. Bayesian statistics also reveal that methods with higher ratios of true positives to false positives give higher overall probabilities and that detection of organic matter in a sample with a higher prior probability of indigenous organic carbon produces greater confidence. Bayesian statistics, therefore, provide guidance for the planning and operation of organic carbon detection activities on Mars. Suggestions for future organic carbon detection missions and instruments are as follows: (i) On Earth, instruments should be tested with analog samples of known organic content to determine their true positive to false positive ratios. (ii) On the mission, for an instrument with a true positive to false positive ratio above one, it should be recognized that each positive detection of organic carbon will result in a progressive increase in the probability of indigenous organic carbon being present; repeated measurements, therefore, can overcome some of the deficiencies of a less-than-definitive test. (iii) For a fixed number of analyses, the highest true positive to false positive ratio method or instrument will provide the greatest probability that indigenous organic carbon is present. (iv) On Mars, analyses should concentrate on samples with highest prior probability of indigenous organic carbon; intuitive desires to contrast samples of high prior probability and low prior

  15. Carbon accumulation in arid croplands of northwest China: pedogenic carbonate exceeding organic carbon

    PubMed Central

    Wang, Xiujun; Wang, Jiaping; Xu, Minggang; Zhang, Wenju; Fan, Tinglu; Zhang, Juan

    2015-01-01

    Soil carbonate (SIC) exceeds organic carbon (SOC) greatly in arid lands, thus may be important for carbon sequestration. However, field data for quantifying carbonate accumulation have been lacking. This study aims to improve our understanding of SIC dynamics and its role in carbon sequestration. We analyzed two datasets of SOC and SIC and their 13C compositions , one with over 100 soil samples collected recently from various land uses in the Yanqi Basin, Xinjiang, and the other with 18 archived soil samples from a long-term experiment (LTE) in Pingliang, Gansu. The data from the Yanqi Basin showed that SOC had a significant relationship with SIC and pedogenic carbonate (PIC); converting shrub land to cropland increased PIC stock by 5.2 kg C m−2, which was 3.6 times of that in SOC stock. The data from the LTE showed greater accumulation of PIC (21–49 g C m−2 year−1) than SOC (10–39 g C m−2 year−1) over 0–20 cm. Our study points out that intensive cropping in the arid and semi-arid regions leads to an increase in both SOC and PIC. Increasing SOC through straw organic amendments enhances PIC accumulation in the arid cropland of northwestern China. PMID:26091554

  16. Carbon accumulation in arid croplands of northwest China: pedogenic carbonate exceeding organic carbon

    NASA Astrophysics Data System (ADS)

    Wang, Xiujun; Wang, Jiaping; Xu, Minggang; Zhang, Wenju; Fan, Tinglu; Zhang, Juan

    2015-06-01

    Soil carbonate (SIC) exceeds organic carbon (SOC) greatly in arid lands, thus may be important for carbon sequestration. However, field data for quantifying carbonate accumulation have been lacking. This study aims to improve our understanding of SIC dynamics and its role in carbon sequestration. We analyzed two datasets of SOC and SIC and their 13C compositions , one with over 100 soil samples collected recently from various land uses in the Yanqi Basin, Xinjiang, and the other with 18 archived soil samples from a long-term experiment (LTE) in Pingliang, Gansu. The data from the Yanqi Basin showed that SOC had a significant relationship with SIC and pedogenic carbonate (PIC); converting shrub land to cropland increased PIC stock by 5.2 kg C m-2, which was 3.6 times of that in SOC stock. The data from the LTE showed greater accumulation of PIC (21-49 g C m-2 year-1) than SOC (10-39 g C m-2 year-1) over 0-20 cm. Our study points out that intensive cropping in the arid and semi-arid regions leads to an increase in both SOC and PIC. Increasing SOC through straw organic amendments enhances PIC accumulation in the arid cropland of northwestern China.

  17. Carbon accumulation in arid croplands of northwest China: pedogenic carbonate exceeding organic carbon.

    PubMed

    Wang, Xiujun; Wang, Jiaping; Xu, Minggang; Zhang, Wenju; Fan, Tinglu; Zhang, Juan

    2015-01-01

    Soil carbonate (SIC) exceeds organic carbon (SOC) greatly in arid lands, thus may be important for carbon sequestration. However, field data for quantifying carbonate accumulation have been lacking. This study aims to improve our understanding of SIC dynamics and its role in carbon sequestration. We analyzed two datasets of SOC and SIC and their (13)C compositions , one with over 100 soil samples collected recently from various land uses in the Yanqi Basin, Xinjiang, and the other with 18 archived soil samples from a long-term experiment (LTE) in Pingliang, Gansu. The data from the Yanqi Basin showed that SOC had a significant relationship with SIC and pedogenic carbonate (PIC); converting shrub land to cropland increased PIC stock by 5.2 kg C m(-2), which was 3.6 times of that in SOC stock. The data from the LTE showed greater accumulation of PIC (21-49 g C m(-2) year(-1)) than SOC (10-39 g C m(-2) year(-1)) over 0-20 cm. Our study points out that intensive cropping in the arid and semi-arid regions leads to an increase in both SOC and PIC. Increasing SOC through straw organic amendments enhances PIC accumulation in the arid cropland of northwestern China. PMID:26091554

  18. Studies and characterisations of various activated carbons used for carbon/carbon supercapacitors

    NASA Astrophysics Data System (ADS)

    Gamby, J.; Taberna, P. L.; Simon, P.; Fauvarque, J. F.; Chesneau, M.

    Various activated carbons from the PICA Company have been tested in supercapacitor cells in order to compare their performances. The differences measured in terms of specific capacitance and cell resistance are presented. Porosity measurements made on activated carbon powders and electrode allowed a better understanding of the electrochemical behaviour of these activated carbons. In this way, the PICACTIF SC carbon was found to be an interesting active material for supercapacitors, with a specific capacitance as high as 125 F/g.

  19. Ultrasonic enhancement of the simultaneous removal of quaternary toxic organic dyes by CuO nanoparticles loaded on activated carbon: Central composite design, kinetic and isotherm study.

    PubMed

    Dashamiri, Somayeh; Ghaedi, Mehrorang; Dashtian, Kheibar; Rahimi, Mahmood Reza; Goudarzi, Alireza; Jannesar, Ramin

    2016-07-01

    Copper oxide nanoparticles loaded on activated carbon (CuO-NPs-AC) were prepared and fully analyzed and characterized with FE-SEM, XRD and FT-IR. Subsequently, this novel material was used for simultaneous ultrasound-assisted adsorption of brilliant green (BG), auramine O (AO), methylene blue (MB) and eosin yellow (EY) dyes. Problems regard to dyes spectra overlap in quaternary solution of this dyes were omitted by derivative spectrophotometric method. The best pH in quaternary system was studied by using one at a time method to achieved maximum dyes removal percentage. Subsequently, sonication time, adsorbent dosage and initial dyes concentrations influence on dyes removal was optimized by central composite design (CCD) combined with desirability function approach (DFA). Desirability score of 0.978 show optimum conditions set at sonication time (4.2 min), adsorbent mass (0.029 g), initial dyes concentration (4.5 mg L(-1)). Under this optimum condition the removal percentage for MB, AO, EY and BG dyes 97.58, 94.66, 96.22 and 94.93, respectively. The adsorption rate well fitted by pseudo second-order while adsorption capacity according to the Langmuir model as best equilibrium isotherm model for BG, MB, AO and EY was 20.48, 21.26, 22.34 and 21.29 mg g(-1), respectively. PMID:26964982

  20. 14C-dead living biomass: evidence for microbial assimilation of ancient organic carbon during shale weathering.

    PubMed

    Petsch, S T; Eglington, T I; Edwards, K J

    2001-05-11

    Prokaryotes have been cultured from a modern weathering profile developed on a approximately 365-million-year-old black shale that use macromolecular shale organic matter as their sole organic carbon source. Using natural-abundance carbon-14 analysis of membrane lipids, we show that 74 to 94% of lipid carbon in these cultures derives from assimilation of carbon-14-free organic carbon from the shale. These results reveal that microorganisms enriched from shale weathering profiles are able to use a macromolecular and putatively refractory pool of ancient organic matter. This activity may facilitate the oxidation of sedimentary organic matter to inorganic carbon when sedimentary rocks are exposed by erosion. Thus, microorganisms may play a more active role in the geochemical carbon cycle than previously recognized, with profound implications for controls on the abundance of oxygen and carbon dioxide in Earth's atmosphere over geologic time. PMID:11283356

  1. Merging allylic carbon-hydrogen and selective carbon-carbon bond activation

    NASA Astrophysics Data System (ADS)

    Masarwa, Ahmad; Didier, Dorian; Zabrodski, Tamar; Schinkel, Marvin; Ackermann, Lutz; Marek, Ilan

    2014-01-01

    Since the nineteenth century, many synthetic organic chemists have focused on developing new strategies to regio-, diastereo- and enantioselectively build carbon-carbon and carbon-heteroatom bonds in a predictable and efficient manner. Ideal syntheses should use the least number of synthetic steps, with few or no functional group transformations and by-products, and maximum atom efficiency. One potentially attractive method for the synthesis of molecular skeletons that are difficult to prepare would be through the selective activation of C-H and C-C bonds, instead of the conventional construction of new C-C bonds. Here we present an approach that exploits the multifold reactivity of easily accessible substrates with a single organometallic species to furnish complex molecular scaffolds through the merging of otherwise difficult transformations: allylic C-H and selective C-C bond activations. The resulting bifunctional nucleophilic species, all of which have an all-carbon quaternary stereogenic centre, can then be selectively derivatized by the addition of two different electrophiles to obtain more complex molecular architecture from these easily available starting materials.

  2. Pesticide sorption on geologic material of varying organic carbon content.

    PubMed

    Bouchard, D C; Wood, A L

    1988-09-01

    Sorption of three pesticides on geologic material ranging in organic carbon content from 0.33 to 6.9 g kg-1 was measured in soil columns using a miscible displacement technique. An octanol-water partitioning model was shown to be inappropriate for predicting sorption of the less hydrophobic pesticides on the low organic carbon materials. PMID:3255290

  3. Black Carbon in Estuarine and Coastal Ocean Dissolved Organic Matter

    NASA Technical Reports Server (NTRS)

    Mannino, Antonio; Harvey, H. Rodger

    2003-01-01

    Analysis of high-molecular-weight dissolved organic matter (DOM) from two estuaries in the northwest Atlantic Ocean reveals that black carbon (BC) is a significant component of previously uncharacterized DOM, suggesting that river-estuary systems are important exporters of recalcitrant dissolved organic carbon to the ocean.

  4. Antimicrobial activity of organic thiosulfates (Bunte salts).

    PubMed

    Stefańska, J Z; Starościak, B J; Orzeszko, A; Kazimierczuk, Z

    1998-03-01

    A number of organic thiosulfates (Bunte salts) were prepared from appropriate primary bromides or iodides. In the case of substrates with long aliphatic chains, an addition of benzyltrimethylammonium chloride as phase transfer catalyst was very successful. The Bunte salts obtained were tested for antibacterial and fungicidal activity by means of the agar disc-diffusion method and by assignation of the minimum inhibitory concentrations (MIC). It was found that the microorganisms Proteus vulgaris, Candida albicans and Staphylococcus aureus showed the highest sensitivity. Biological activity of the compounds studied was dependent on the length of the aliphatic chain. Among the investigated compounds, aliphatic thiosulfates with 10-13 carbon atom chain were the most potent. PMID:9547520

  5. Organic carbon hidden in urban ecosystems

    PubMed Central

    Edmondson, Jill L.; Davies, Zoe G.; McHugh, Nicola; Gaston, Kevin J.; Leake, Jonathan R.

    2012-01-01

    Urbanization is widely presumed to degrade ecosystem services, but empirical evidence is now challenging these assumptions. We report the first city-wide organic carbon (OC) budget for vegetation and soils, including under impervious surfaces. Urban soil OC storage was significantly greater than in regional agricultural land at equivalent soil depths, however there was no significant difference in storage between soils sampled beneath urban greenspaces and impervious surfaces, at equivalent depths. For a typical U.K. city, total OC storage was 17.6 kg m−2 across the entire urban area (assuming 0 kg m−2 under 15% of land covered by buildings). The majority of OC (82%) was held in soils, with 13% found under impervious surfaces, and 18% stored in vegetation. We reveal that assumptions underpinning current national estimates of ecosystem OC stocks, as required by Kyoto Protocol signatories, are not robust and are likely to have seriously underestimated the contributions of urban areas. PMID:23236585

  6. Organic carbon accumulation in Brazilian mangal sediments

    NASA Astrophysics Data System (ADS)

    Sanders, Christian J.; Smoak, Joseph M.; Sanders, Luciana M.; Sathy Naidu, A.; Patchineelam, Sambasiva R.

    2010-12-01

    This study reviews the organic carbon (OC) accumulation rates in mangrove forests, margins and intertidal mudflats in geographically distinct areas along the Brazilian coastline (Northeastern to Southern). Our initial results indicate that the mangrove forests in the Northeastern region of Brazil are accumulating more OC (353 g/m 2/y) than in the Southeastern areas (192 g/m 2/y) being that the sediment accumulation rates, 2.8 and 2.5 mm/y, and OC content ˜7.1% and ˜5.8% (dry sediment weight) were contributing factors to the discrepancies between the forests. The intertidal mudflats on the other hand showed substantially greater OC accumulation rates, sedimentation rates and content 1129 g/m 2/y and 234 g/m 2/y; 7.3 and 3.4 mm/y; 10.3% and ˜2.7% (OC of dry sediment weight content), respectively, in the Northeastern compared to the Southeastern region. Mangrove forests in the South-Southeastern regions of Brazil may be more susceptible to the rising sea level, as they are geographically constricted by the vast mountain ranges along the coastline.

  7. Net carbon flux in organic and conventional olive production systems

    NASA Astrophysics Data System (ADS)

    Saeid Mohamad, Ramez; Verrastro, Vincenzo; Bitar, Lina Al; Roma, Rocco; Moretti, Michele; Chami, Ziad Al

    2014-05-01

    Agricultural systems are considered as one of the most relevant sources of atmospheric carbon. However, agriculture has the potentiality to mitigate carbon dioxide mainly through soil carbon sequestration. Some agricultural practices, particularly fertilization and soil management, can play a dual role in the agricultural systems regarding the carbon cycle contributing to the emissions and to the sequestration process in the soil. Good soil and input managements affect positively Soil Organic Carbon (SOC) changes and consequently the carbon cycle. The present study aimed at comparing the carbon footprint of organic and conventional olive systems and to link it to the efficiency of both systems on carbon sequestration by calculating the net carbon flux. Data were collected at farm level through a specific and detailed questionnaire based on one hectare as a functional unit and a system boundary limited to olive production. Using LCA databases particularly ecoinvent one, IPCC GWP 100a impact assessment method was used to calculate carbon emissions from agricultural practices of both systems. Soil organic carbon has been measured, at 0-30 cm depth, based on soil analyses done at the IAMB laboratory and based on reference value of SOC, the annual change of SOC has been calculated. Substracting sequestrated carbon in the soil from the emitted on resulted in net carbon flux calculation. Results showed higher environmental impact of the organic system on Global Warming Potential (1.07 t CO2 eq. yr-1) comparing to 0.76 t CO2 eq. yr-1 in the conventional system due to the higher GHG emissions caused by manure fertilizers compared to the use of synthetic foliar fertilizers in the conventional system. However, manure was the main reason behind the higher SOC content and sequestration in the organic system. As a resultant, the organic system showed higher net carbon flux (-1.7 t C ha-1 yr-1 than -0.52 t C ha-1 yr-1 in the conventional system reflecting higher efficiency as a

  8. Inferring Absorbing Organic Carbon Content from AERONET Data

    NASA Technical Reports Server (NTRS)

    Arola, A.; Schuster, G.; Myhre, G.; Kazadzis, S.; Dey, S.; Tripathi, S. N.

    2011-01-01

    Black carbon, light-absorbing organic carbon (often called brown carbon) and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated globally the amount of light absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon) levels in biomass burning regions of South-America and Africa are relatively high (about 15-20 magnesium per square meters during biomass burning season), while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30-35 magnesium per square meters during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while opposite is true in urban areas in India and China.

  9. Organic carbon inventories in natural and restored Ecuadorian mangrove forests

    PubMed Central

    Bruno, John F.; Benninger, Larry; Alperin, Marc; de Dios Morales, Juan

    2014-01-01

    Mangroves can capture and store organic carbon and their protection and therefore their restoration is a component of climate change mitigation. However, there are few empirical measurements of long-term carbon storage in mangroves or of how storage varies across environmental gradients. The context dependency of this process combined with geographically limited field sampling has made it difficult to generalize regional and global rates of mangrove carbon sequestration. This has in turn hampered the inclusion of sequestration by mangroves in carbon cycle models and in carbon offset markets. The purpose of this study was to estimate the relative carbon capture and storage potential in natural and restored mangrove forests. We measured depth profiles of soil organic carbon content in 72 cores collected from six sites (three natural, two restored, and one afforested) surrounding Muisne, Ecuador. Samples up to 1 m deep were analyzed for organic matter content using loss-on-ignition and values were converted to organic carbon content using an accepted ratio of 1.72 (g/g). Results suggest that average soil carbon storage is 0.055 ± 0.002 g cm−3 (11.3 ± 0.8% carbon content by dry mass, mean ± 1 SE) up to 1 m deep in natural sites, and 0.058 ± 0.002 g cm−3 (8.0 ± 0.3%) in restored sites. These estimates are concordant with published global averages. Evidence of equivalent carbon stocks in restored and afforested mangrove patches emphasizes the carbon sink potential for reestablished mangrove systems. We found no relationship between sediment carbon storage and aboveground biomass, forest structure, or within-patch location. Our results demonstrate the long-term carbon storage potential of natural mangroves, high effectiveness of mangrove restoration and afforestation, a lack of predictability in carbon storage strictly based on aboveground parameters, and the need to establish standardized protocol for quantifying mangrove sediment carbon stocks. PMID:24883249

  10. Organic carbon inventories in natural and restored Ecuadorian mangrove forests.

    PubMed

    DelVecchia, Amanda G; Bruno, John F; Benninger, Larry; Alperin, Marc; Banerjee, Ovik; de Dios Morales, Juan

    2014-01-01

    Mangroves can capture and store organic carbon and their protection and therefore their restoration is a component of climate change mitigation. However, there are few empirical measurements of long-term carbon storage in mangroves or of how storage varies across environmental gradients. The context dependency of this process combined with geographically limited field sampling has made it difficult to generalize regional and global rates of mangrove carbon sequestration. This has in turn hampered the inclusion of sequestration by mangroves in carbon cycle models and in carbon offset markets. The purpose of this study was to estimate the relative carbon capture and storage potential in natural and restored mangrove forests. We measured depth profiles of soil organic carbon content in 72 cores collected from six sites (three natural, two restored, and one afforested) surrounding Muisne, Ecuador. Samples up to 1 m deep were analyzed for organic matter content using loss-on-ignition and values were converted to organic carbon content using an accepted ratio of 1.72 (g/g). Results suggest that average soil carbon storage is 0.055 ± 0.002 g cm(-3) (11.3 ± 0.8% carbon content by dry mass, mean ± 1 SE) up to 1 m deep in natural sites, and 0.058 ± 0.002 g cm(-3) (8.0 ± 0.3%) in restored sites. These estimates are concordant with published global averages. Evidence of equivalent carbon stocks in restored and afforested mangrove patches emphasizes the carbon sink potential for reestablished mangrove systems. We found no relationship between sediment carbon storage and aboveground biomass, forest structure, or within-patch location. Our results demonstrate the long-term carbon storage potential of natural mangroves, high effectiveness of mangrove restoration and afforestation, a lack of predictability in carbon storage strictly based on aboveground parameters, and the need to establish standardized protocol for quantifying mangrove sediment carbon stocks. PMID:24883249

  11. [Effects of land use change on soil labile organic carbon in Central Jiangxi of China].

    PubMed

    Du, Man-Yi; Fan, Shao-Hui; Liu, Guang-Lu; Qi, Liang-Hua; Guo, Bao-Hu; Tang, Xiao-Lu; Xiao, Fu-Ming

    2013-10-01

    Selecting the 15-year abandoned land (AL) and three forest lands [Phyllostachys edulis plantation (PE), Schima superba secondary forest (SS), and Cunninghamia Lanceolata plantation (CL)] in Anfu County of Jiangxi Province as test objects, this paper studied the effects of land use change on the soil organic carbon (SOC) pool and soil labile organic carbon (SLOC) contents. The soil organic carbon (SOC), microbial biomass carbon (MBC), hot- water extractable carbon (HWC), and readily oxidizable carbon (ROC) contents in the test lands were all in the order of PE>CL>SS>AL. As compared with those in AL, the SOC content, soil carbon stock, and soil labile organic carbon (SLOC) contents in the three forest lands all decreased with increasing soil depth, and had an obvious accumulation in surface soil. The proportions of different kinds of SLOC to soil total organic carbon differed markedly, among which, ROC had the highest proportion, while MBC had the smallest one. There existed significant relationships between SOC, MBC, HWC, and ROC. The MBC, HWC, and ROC contained higher content of active carbon, and were more sensitive to the land use change, being able to be used as the indicators for evaluating the soil quality and fertility in central Jiangxi Province. PMID:24483085

  12. COMPARISON OF SAMPLING METHODS FOR SEMI-VOLATILE ORGANIC CARBON ASSOCIATED WITH PM 2.5

    EPA Science Inventory

    This study evaluates the influence of denuder sampling methods and filter collection media on the measurement of semi-volatile organic carbon (SVOC) associated with PM2.5. Two types of collection media, charcoal (activated carbon) and XAD, were used both in diffusion denuders ...

  13. Organic carbon flow in a swamp-stream ecosystem

    SciTech Connect

    Mulholland, P.J.

    1981-01-01

    An annual organic carbon budget is presented for an 8-km segment of Creeping Swamp, an undisturbed, third-order swamp-stream in the Coastal Plain of North Carolina, USA. Annual input of organic carbon (588 gC/m/sup 2/) was 96% allochthonous and was dominated by leaf litter inputs (36%) and fluvial, dissolved organic carbon (DOC) inputs (31%). Although the swamp-stream was primarily heterotrophic, autochthonous organic carbon input, primarily from filamentous algae, was important during February and March when primary production/ecosystem respiration (P/R) ratios of the flooded portions were near one. Annual output of organic carbon via fluvial processes (214 gC/m/sup 2/), 95% as DOC, was 36% of total annual inputs, indicating that the swamp-stream segment ecosystem was 64% efficient at retaining organic carbon. Organic carbon dynamics in the Creeping Swamp segment were compared to those reported for upland stream segments using indices of organic matter processing suggested by Fisher (1977) and a loading potential index suggested here. Creeping Swamp, while loading at a high rate, retains a much larger portion of its organic carbon inputs than two upland streams. Despite the high degree of retention and oxidation of organic inputs to Creeping Swamp, there is a net annual fluvial export of 21 gC/m/sup 2/, mostly in the dissolved form. Watersheds drained by swamp-streams in the southeastern United States are thought to have large organic carbon exports compared to upland forested drainages, because the stream network covers a much greater proportion of the total watershed area.

  14. Investigation of reductive dechlorination supported by natural organic carbon

    USGS Publications Warehouse

    Rectanus, H.V.; Widdowson, M.A.; Chapelle, F.H.; Kelly, C.A.; Novak, J.T.

    2007-01-01

    Because remediation timeframes using monitored natural attenuation may span decades or even centuries at chlorinated solvent sites, new approaches are needed to assess the long-term sustainability of reductive dechlorination in ground water systems. In this study, extraction procedures were used to investigate the mass of indigenous organic carbon in aquifer sediment, and experiments were conducted to determine if the extracted carbon could support reductive dechlorination of chloroethenes. Aquifer sediment cores were collected from a site without an anthropogenic source of organic carbon where organic carbon varied from 0.02% to 0.12%. Single extraction results showed that 1% to 28% of sediment-associated organic carbon and 2% to 36% of the soft carbon were removed depending on nature and concentration of the extracting solution (Nanopure water; 0.1%, 0.5%, and 1.0% sodium pyrophosphate; and 0.5 N sodium hydroxide). Soft carbon is defined as organic carbon oxidized with potassium persulfate and is assumed to serve as a source of biodegradable carbon within the aquifer. Biodegradability studies demonstrated that 20% to 40% of extracted organic carbon was biodegraded aerobically and anaerobically by soil microorganisms in relatively brief tests (45 d). A five-step extraction procedure consisting of 0.1% pyrophosphate and base solutions was investigated to quantify bioavailable organic carbon. Using the extracted carbon as the sole electron donor source, tetrachloroethene was transformed to cis-1,2- dichloroethene and vinyl chloride in anaerobic enrichment culture experiments. Hydrogen gas was produced at levels necessary to sustain reductive dechlorination (>1 nM). ?? 2007 National Ground Water Association.

  15. Stable carbon isotope depth profiles and soil organic carbon dynamics in the lower Mississippi Basin

    USGS Publications Warehouse

    Wynn, J.G.; Harden, J.W.; Fries, T.L.

    2006-01-01

    Analysis of depth trends of 13C abundance in soil organic matter and of 13C abundance from soil-respired CO2 provides useful indications of the dynamics of the terrestrial carbon cycle and of paleoecological change. We measured depth trends of 13C abundance from cropland and control pairs of soils in the lower Mississippi Basin, as well as the 13C abundance of soil-respired CO2 produced during approximately 1-year soil incubation, to determine the role of several candidate processes on the 13C depth profile of soil organic matter. Depth profiles of 13C from uncultivated control soils show a strong relationship between the natural logarithm of soil organic carbon concentration and its isotopic composition, consistent with a model Rayleigh distillation of 13C in decomposing soil due to kinetic fractionation during decomposition. Laboratory incubations showed that initially respired CO 2 had a relatively constant 13C content, despite large differences in the 13C content of bulk soil organic matter. Initially respired CO2 was consistently 13C-depleted with respect to bulk soil and became increasingly 13C-depleted during 1-year, consistent with the hypothesis of accumulation of 13C in the products of microbial decomposition, but showing increasing decomposition of 13C-depleted stable organic components during decomposition without input of fresh biomass. We use the difference between 13C / 12C ratios (calculated as ??-values) between respired CO 2 and bulk soil organic carbon as an index of the degree of decomposition of soil, showing trends which are consistent with trends of 14C activity, and with results of a two-pooled kinetic decomposition rate model describing CO2 production data recorded during 1 year of incubation. We also observed inconsistencies with the Rayleigh distillation model in paired cropland soils and reasons for these inconsistencies are discussed. ?? 2005 Elsevier B.V. All rights reserved.

  16. First Molecular Dynamics simulation insight into the mechanism of organics adsorption from aqueous solutions on microporous carbons

    NASA Astrophysics Data System (ADS)

    Terzyk, Artur P.; Gauden, Piotr A.; Zieliński, Wojciech; Furmaniak, Sylwester; Wesołowski, Radosław P.; Klimek, Kamil K.

    2011-10-01

    The results of 84 MD simulations showing the influence of porosity and carbon surface oxidation on adsorption of three organic compounds from aqueous solutions on carbons are reported. Based on a model of 'soft' activated carbon, three carbon structures with gradually changed microporosity were created. Next, different number of surface oxygen groups was introduced. We observe quantitative agreement between simulation and experiment i.e. the decrease in adsorption from benzene down to paracetamol. Simulation results clearly demonstrate that the balance between porosity and carbon surface chemical composition in organics adsorption on carbons, and the pore blocking determine adsorption properties of carbons.

  17. Temporal evolution of organic carbon concentrations in Swiss lakes: trends of allochthonous and autochthonous organic carbon.

    PubMed

    Rodríguez-Murillo, J C; Filella, M

    2015-07-01

    Evaluation of time series of organic carbon (OC) concentrations in lakes is useful for monitoring some of the effects of global change on lakes and their catchments. Isolating the evolution of autochthonous and allochthonous lake OC might be a useful way to differentiate between drivers of soil and photosynthetic OC related changes. However, there are no temporal series for autochthonous and allochthonous lake OC. In this study, a new approach has been developed to construct time series of these two categories of OC from existing dissolved organic carbon (DOC) data. First, temporal series (longer than ten years) of OC have been compiled for seven big Swiss lakes and another 27 smaller ones and evaluated by using appropriate non-parametric statistical methods. Subsequently, the new approach has been applied to construct time series of autochthonous and allochthonous lake OC in the seven big lakes. Doing this was possible because long term series of DOC concentrations at different depths are available for these lakes. Organic carbon concentrations generally increase in big lakes and decrease in smaller ones, although only in some cases are these trends statistically significant. The magnitude of the observed changes is generally small in big lakes (<1% annual change) and larger in smaller lakes. Autochthonous DOC concentrations in big lakes increase or decrease depending on the lake and the station but allochthonous DOC concentrations generally increase. This pattern is consistent with an increase in the OC input from the lakes' catchments and/or an increase in the refractoriness of the OC in question, and with a temporal evolution of autochthonous DOC depending on the degree of recovery from past eutrophication of each particular lake. In small lakes, OC dynamics are mainly driven by decreasing biological productivity, which in many, but not all cases, outweighs the probable increase of allochthonous OC. PMID:25782080

  18. Adsorption of selected volatile organic vapors on multiwall carbon nanotubes.

    PubMed

    Shih, Yang-hsin; Li, Mei-syue

    2008-06-15

    Carbon nanotubes are expected to play an important role in sensing, pollution treatment and separation techniques. This study examines the adsorption behaviors of volatile organic compounds (VOCs), n-hexane, benzene, trichloroethylene and acetone on two multiwall carbon nanotubes (MWCNTs), CNT1 and CNT2. Among these VOCs, acetone exhibits the highest adsorption capacity. The highest adsorption enthalpies and desorption energies of acetone were also observed. The strong chemical interactions between acetone and both MWCNTs may be the result from chemisorption on the topological defects. The adsorption heats of trichloroethylene, benzene, and n-hexane are indicative of physisorption on the surfaces of both MWCNTs. CNT2 presents a higher adsorption capacity than CNT1 due to the existence of an exterior amorphous carbon layer on CNT2. The amorphous carbon enhances the adsorption capacity of organic chemicals on carbon nanotubes. The morphological and structure order of carbon nanotubes are the primary affects on the adsorption process of organic chemicals. PMID:17980962

  19. TESTING GUIDELINES FOR TECHNETIUM-99 ABSORPTION ON ACTIVATED CARBON

    SciTech Connect

    BYRNES ME

    2010-09-08

    CH2M HILL Plateau Remediation Company (CHPRC) is currently evaluating the potential use of activated carbon adsorption for removing technetium-99 from groundwater as a treatment method for the Hanford Site's 200 West Area groundwater pump-and-treat system. The current pump-and-treat system design will include an ion-exchange (IX) system for selective removal of technetium-99 from selected wells prior to subsequent treatment of the water in the central treatment system. The IX resin selected for technetium-99 removal is Purolite A530E. The resin service life is estimated to be approximately 66.85 days at the design technetium-99 loading rate, and the spent resin must be replaced because it cannot be regenerated. The resulting operating costs associated with resin replacement every 66.85 days are estimated at $0.98 million/year. Activated carbon pre-treatment is being evaluated as a potential cost-saving measure to offset the high operating costs associated with frequent IX resin replacement. This document is preceded by the Literature Survey of Technetium-99 Groundwater Pre-Treatment Option Using Granular Activated Carbon (SGW-43928), which identified and evaluated prior research related to technetium-99 adsorption on activated carbon. The survey also evaluated potential operating considerations for this treatment approach for the 200 West Area. The preliminary conclusions of the literature survey are as follows: (1) Activated carbon can be used to selectively remove technetium-99 from contaminated groundwater. (2) Technetium-99 adsorption onto activated carbon is expected to vary significantly based on carbon types and operating conditions. For the treatment approach to be viable at the Hanford Site, activated carbon must be capable of achieving a designated minimum technetium-99 uptake. (3) Certain radionuclides known to be present in 200 West Area groundwater are also likely to adsorb onto activated carbon. (4) Organic solvent contaminants of concern (COCs) will

  20. Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon

    SciTech Connect

    Abdullah, N.; Muhammad, I. S.; Hamid, S. B. Abd.; Rinaldi, A.; Su, D. S.; Schlogl, R.

    2009-06-01

    Carbon-carbon composite of activated carbon and carbon nanofibers have been synthesized by growing Carbon nanofiber (CNF) on Palm shell-based Activated carbon (AC) with Ni catalyst. The composites are in an agglomerated shape due to the entanglement of the defective CNF between the AC particles forming a macroscopic body. The macroscopic size will allow the composite to be used as a stabile catalyst support and liquid adsorbent. The preparation of CNT/AC nanocarbon was initiated by pre-treating the activated carbon with nitric acid, followed by impregnation of 1 wt% loading of nickel (II) nitrate solutions in acetone. The catalyst precursor was calcined and reduced at 300 deg. C for an hour in each step. The catalytic growth of nanocarbon in C{sub 2}H{sub 4}/H{sub 2} was carried out at temperature of 550 deg. C for 2 hrs with different rotating angle in the fluidization system. SEM and N{sub 2} isotherms show the level of agglomeration which is a function of growth density and fluidization of the system. The effect of fluidization by rotating the reactor during growth with different speed give a significant impact on the agglomeration of the final CNF/AC composite and thus the amount of CNFs produced. The macrostructure body produced in this work of CNF/AC composite will have advantages in the adsorbent and catalyst support application, due to the mechanical and chemical properties of the material.

  1. Important role for organic carbon in subduction-zone fluids in the deep carbon cycle

    NASA Astrophysics Data System (ADS)

    Sverjensky, Dimitri A.; Stagno, Vincenzo; Huang, Fang

    2014-12-01

    Supercritical aqueous fluids link subducting plates and the return of carbon to Earth's surface in the deep carbon cycle. The amount of carbon in the fluids and the identities of the dissolved carbon species are not known, which leaves the deep carbon budget poorly constrained. Traditional models, which assume that carbon exists in deep fluids as dissolved gas molecules, cannot predict the solubility and ionic speciation of carbon in its silicate rock environment. Recent advances enable these limitations to be overcome when evaluating the deep carbon cycle. Here we use the Deep Earth Water theoretical model to calculate carbon speciation and solubility in fluids under upper mantle conditions. We find that fluids in equilibrium with mantle peridotite minerals generally contain carbon in a dissolved gas molecule form. However, fluids in equilibrium with diamonds and eclogitic minerals in the subducting slab contain abundant dissolved organic and inorganic ionic carbon species. The high concentrations of dissolved carbon species provide a mechanism to transport large amounts of carbon out of the subduction zone, where the ionic carbon species may influence the oxidation state of the mantle wedge. Our results also identify novel mechanisms that can lead to diamond formation and the variability of carbon isotopic composition via precipitation of the dissolved organic carbon species in the subduction-zone fluids.

  2. Preparation and characterization of activated carbon aerogel spheres

    NASA Astrophysics Data System (ADS)

    Liu, Ning; Liu, Fengshou

    2014-03-01

    Activated carbon aerogel spheres (A-CAS) were successfully prepared by imposing KOH activation on aerogel spheres. It was found that the activation treatment did not destroy the order of the surface of the carbon aerogel spheres (CAS), but it improved the pore structure and adsorption performance of the products. With increasing burn-off, the amount of mesopores first decreased and then increased, with the amount of micropores continuously increasing. The highest measured BET surface area and micropore surface area reached 1198 and 786 m2/g, respectively. The adsorption capacity of benzene organic vapour on the A-CAS is more than eight times as large as that on CAS.

  3. Substrate and environmental controls on microbial assimilation of soil organic carbon: a framework for Earth System Models

    SciTech Connect

    Xu, Xiaofeng; Schimel, Joshua; Thornton, Peter E; Song, Xia; Yuan, Fengming; Goswami, Santonu

    2014-01-01

    Microbial assimilation of soil organic carbon is one of the fundamental processes of global carbon cycling and it determines the magnitude of microbial biomass in soils. Mechanistic understanding of microbial assimilation of soil organic carbon and its controls is important for to improve Earth system models ability to simulate carbon-climate feedbacks. Although microbial assimilation of soil organic carbon is broadly considered to be an important parameter, it really comprises two separate physiological processes: one-time assimilation efficiency and time-dependent microbial maintenance energy. Representing of these two mechanisms is crucial to more accurately simulate carbon cycling in soils. In this study, a simple modeling framework was developed to evaluate the substrate and environmental controls on microbial assimilation of soil organic carbon using a new term: microbial annual active period (the length of microbes remaining active in one year). Substrate quality has a positive effect on microbial assimilation of soil organic carbon: higher substrate quality (lower C:N ratio) leads to higher ratio of microbial carbon to soil organic carbon and vice versa. Increases in microbial annual active period from zero stimulate microbial assimilation of soil organic carbon; however, when microbial annual active period is longer than an optimal threshold, increasing this period decreases microbial biomass. The simulated ratios of soil microbial biomass to soil organic carbon are reasonably consistent with a recently compiled global dataset at the biome-level. The modeling framework of microbial assimilation of soil organic carbon and its controls developed in this study offers an applicable ways to incorporate microbial contributions to the carbon cycling into Earth system models for simulating carbon-climate feedbacks and to explain global patterns of microbial biomass.

  4. Fossil organic carbon in wastewater and its fate in treatment plants.

    PubMed

    Law, Yingyu; Jacobsen, Geraldine E; Smith, Andrew M; Yuan, Zhiguo; Lant, Paul

    2013-09-15

    This study reports the presence of fossil organic carbon in wastewater and its fate in wastewater treatment plants. The findings pinpoint the inaccuracy of current greenhouse gas accounting guidelines which defines all organic carbon in wastewater to be of biogenic origin. Stable and radiocarbon isotopes ((13)C and (14)C) were measured throughout the process train in four municipal wastewater treatment plants equipped with secondary activated sludge treatment. Isotopic mass balance analyses indicate that 4-14% of influent total organic carbon (TOC) is of fossil origin with concentrations between 6 and 35 mg/L; 88-98% of this is removed from the wastewater. The TOC mass balance analysis suggests that 39-65% of the fossil organic carbon from the influent is incorporated into the activated sludge through adsorption or from cell assimilation while 29-50% is likely transformed to carbon dioxide (CO2) during secondary treatment. The fossil organic carbon fraction in the sludge undergoes further biodegradation during anaerobic digestion with a 12% decrease in mass. 1.4-6.3% of the influent TOC consists of both biogenic and fossil carbon is estimated to be emitted as fossil CO2 from activated sludge treatment alone. The results suggest that current greenhouse gas accounting guidelines, which assume that all CO2 emission from wastewater is biogenic may lead to underestimation of emissions. PMID:23863394

  5. SAMPLING DURATION DEPENDENCE OF SEMI-CONTINUOUS ORGANIC CARBON MEASUREMENTS ON STEADY STATE SECONDARY ORGANIC AEROSOLS

    EPA Science Inventory

    Semi-continuous organic carbon concentrations were measured through several experiments of statically generated secondary organic aerosol formed by hydrocarbon + NOx irradiations. Repeated, randomized measurements of these steady state aerosols reveal decreases in the observed c...

  6. ACTIVATED CARBON TREATMENT OF INDUSTRIAL WASTEWATERS: SELECTED TECHNICAL PAPERS

    EPA Science Inventory

    Because of the tremendous interest in the organic constituent removal by activated carbon, the two industrial categories displaying the most interest are the petroleum refining and petrochemical industries. EPA's Office of Research and Development has co-sponsored two technical s...

  7. Organic chemistry of Murchison meteorite: Carbon isotopic fractionation

    NASA Technical Reports Server (NTRS)

    Yuen, G. U.; Blair, N. E.; Desmarais, D. J.; Cronin, J. R.; Chang, S.

    1986-01-01

    The carbon isotopic composition of individual organic compounds of meteoritic origin remains unknown, as most reported carbon isotopic ratios are for bulk carbon or solvent extractable fractions. The researchers managed to determine the carbon isotopic ratios for individual hydrocarbons and monocarboxylic acids isolated from a Murchison sample by a freeze-thaw-ultrasonication technique. The abundances of monocarboxylic acids and saturated hydrocarbons decreased with increasing carbon number and the acids are more abundant than the hydrocarbon with the same carbon number. For both classes of compounds, the C-13 to C-12 ratios decreased with increasing carbon number in a roughly parallel manner, and each carboxylic acid exhibits a higher isotopic number than the hydrocarbon containing the same number of carbon atoms. These trends are consistent with a kinetically controlled synthesis of higher homologues for lower ones.

  8. Environmental analyse of soil organic carbon stock changes in Slovakia

    NASA Astrophysics Data System (ADS)

    Koco, Š.; Barančíková, G.; Skalský, R.; Tarasovičová, Z.; Gutteková, M.; Halas, J.; Makovníková, J.; Novákova, M.

    2012-04-01

    The content and quality of soil organic matter is one of the basic soil parameters on which soil production functioning depends as well as it is active in non production soil functions like an ecological one especially. Morphologic segmentation of Slovakia has significant influence of structure in using agricultural soil in specific areas of our territory. Also social changes of early 90´s of 20´th century made their impact on change of using of agricultural soil (transformation from large farms to smaller ones, decreasing the number of livestock). This research is studying changes of development of soil organic carbon stock (SOC) in agricultural soil of Slovakia as results of climatic as well as social and political changes which influenced agricultury since last 40 years. The main goal of this research is an analysis of soil organic carbon stock since 1970 until now at specific agroclimatic regions of Slovakia and statistic analysis of relation between modelled data of SOC stock and soil quality index value. Changes of SOC stock were evaluated on the basis SOC content modeling using RothC-26.3 model. From modeling of SOC stock results the outcome is that in that time the soil organic carbon stock was growing until middle 90´s years of 20´th century with the highest value in 1994. Since that year until new millennium SOC stock is slightly decreasing. After 2000 has slightly increased SOC stock so far. According to soil management SOC stock development on arable land is similar to overall evolution. In case of grasslands after slight growth of SOC stock since 1990 the stock is in decline. This development is result of transformational changes after 1989 which were specific at decreasing amount of organic carbon input from organic manure at grassland areas especially. At warmer agroclimatic regions where mollic fluvisols and chernozems are present and where are soils with good quality and steady soil organic matter (SOM) the amount of SOC in monitored time is

  9. Organic carbon isotope constraints on the dissolved organic carbon (DOC) reservoir at the Cryogenian-Ediacaran transition

    NASA Astrophysics Data System (ADS)

    Jiang, Ganqing; Wang, Xinqiang; Shi, Xiaoying; Zhang, Shihong; Xiao, Shuhai; Dong, Jin

    2010-10-01

    Prominent negative carbonate carbon isotope (δ 13C carb) anomalies from some Ediacaran successions are accompanied by invariant or decoupled organic carbon isotope (δ 13C org) values and have been interpreted as resulting from the remineralization of a large dissolved organic carbon (DOC) reservoir capable of buffering carbon isotopes of organic matter. This inferred oceanic DOC reservoir was thought to have initiated with the onset of Cryogenian glaciations (ca. 720 Ma) and lasted for millions of years until the late Ediacaran Period (< 560 Ma). Carbon isotope analyses of the basal Doushantuo Formation (ca. 635 Ma) in south China reveal that (1) the cap carbonate has δ 13C org around -26‰ (VPDB) and relatively low Δδ 13C (22 ± 2‰) and (2) the overlying organic-rich black shale and shaly dolostone have more negative δ 13C org (-28‰ to -35‰) and higher Δδ 13C (28‰-30‰). Both δ 13C carb and δ 13C org show a + 6‰ shift within a 4-m-thick interval overlying the Doushantuo cap carbonate. The δ 13C org values of the cap carbonate are associated with low TOC (mostly < 0.1%); their paleoceanographic significance requires further tests in other Ediacaran basins. The co-varying positive shift in δ 13C carb and δ 13C org following cap carbonate deposition is best interpreted as resulting from a rapid increase in organic carbon burial, which may have resulted in the rise of oxygen and heralded the first appearance of animals a few meters above the Doushantuo cap carbonate. The data suggest that a large oceanic DOC reservoir did not exist in the early Ediacaran ocean. Excess oceanic DOC required to explain the Ediacaran Shuram and upper Doushantuo δ 13C excursions, if it existed, had to be developed during the Ediacaran Period after cap carbonate deposition.

  10. Soil organic carbon enrichment of dust emissions: Magnitude, mechanisms and its implications for the carbon cycle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil erosion is an important component of the global carbon cycle. However, little attention has been given to the role of aeolian processes in influencing soil organic carbon (SOC) flux and the release of greenhouse gasses, such as carbon-dioxide (CO2), to the atmosphere. Understanding the magnitu...

  11. Limits to soil carbon stability; Deep, ancient soil carbon decomposition stimulated by new labile organic inputs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil carbon (C) pools store about one-third of the total terrestrial organic carbon. Deep soil C pools (below 1 m) are thought to be stable due to their low biodegradability, but little is known about soil microbial processes and carbon dynamics below the soil surface, or how global change might aff...

  12. Nonoxidative removal of organics in the activated sludge process

    PubMed Central

    Modin, Oskar; Persson, Frank; Wilén, Britt-Marie; Hermansson, Malte

    2016-01-01

    ABSTRACT The activated sludge process is commonly used to treat wastewater by aerobic oxidation of organic pollutants into carbon dioxide and water. However, several nonoxidative mechanisms can also contribute to removal of organics. Sorption onto activated sludge can remove a large fraction of the colloidal and particulate wastewater organics. Intracellular storage of, e.g., polyhydroxyalkanoates (PHA), triacylglycerides (TAG), or wax esters can convert wastewater organics into precursors for high-value products. Recently, several environmental, economic, and technological drivers have stimulated research on nonoxidative removal of organics for wastewater treatment. In this paper, we review these nonoxidative removal mechanisms as well as the existing and emerging process configurations that make use of them for wastewater treatment. Better utilization of nonoxidative processes in activated sludge could reduce the wasteful aerobic oxidation of organic compounds and lead to more resource-efficient wastewater treatment plants. PMID:27453679

  13. Soil salinity decreases global soil organic carbon stocks.

    PubMed

    Setia, Raj; Gottschalk, Pia; Smith, Pete; Marschner, Petra; Baldock, Jeff; Setia, Deepika; Smith, Jo

    2013-11-01

    Saline soils cover 3.1% (397 million hectare) of the total land area of the world. The stock of soil organic carbon (SOC) reflects the balance between carbon (C) inputs from plants, and losses through decomposition, leaching and erosion. Soil salinity decreases plant productivity and hence C inputs to the soil, but also microbial activity and therefore SOC decomposition rates. Using a modified Rothamsted Carbon model (RothC) with a newly introduced salinity decomposition rate modifier and a plant input modifier we estimate that, historically, world soils that are currently saline have lost an average of 3.47 tSOC ha(-1) since they became saline. With the extent of saline soils predicted to increase in the future, our modelling suggests that world soils may lose 6.8 Pg SOC due to salinity by the year 2100. Our findings suggest that current models overestimate future global SOC stocks and underestimate net CO2 emissions from the soil-plant system by not taking salinity effects into account. From the perspective of enhancing soil C stocks, however, given the lower SOC decomposition rate in saline soils, salt tolerant plants could be used to sequester C in salt-affected areas. PMID:22959898

  14. [Effects of Chinese fir litter on soil organic carbon decomposition and microbial biomass carbon].

    PubMed

    Wang, Xiao-Feng; Wang, Si-Long; Zhang, Wei-Dong

    2013-09-01

    By using 13C stable isotope tracer technique, this paper studied the effects of Chinese fir litter addition on the soil organic carbon (SOC) decomposition, microbial biomass carbon, and dissolved organic carbon in 0-5 cm and 40-45 cm layers. The decomposition rate of SOC in 40-45 cm layer was significantly lower than that in 0-5 cm layer, but the priming effect induced by the Chinese fir litter addition showed an opposite trend. The Chinese fir litter addition increased the soil total microbial biomass carbon and the microbial biomass carbon derived from native soil significantly, but had less effects on the soil dissolved organic carbon. Turning over the subsoil to the surface of the woodland could accelerate the soil carbon loss in Chinese fir plantation due to the priming effect induced by the litters. PMID:24417093

  15. Evaluation of organic carbon analyzers for space application. [for water reclamation

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The state-of-the-art technology for organic carbon analysis in space applications is evaluated. An investigation into total organic carbon (TOC) analysis has identified a variety of schemes which include different methods for: (1) separation of inorganic carbon from organic carbon and/or differentiation of inorganic carbon from organic carbon; (2) reaction of organic carbon to form a quantifiable species; and (3) detection and measurement of that species. Each method option is discussed.

  16. DISSOLVED ORGANIC CARBON (DOC) CONCENTRATIONS IN SMALL STREAMS OF THE GEORGIA PIEDMONT

    EPA Science Inventory

    Dissolved organic matter (DOM) supports microbial activity and contributes to transport of N and P in streams. We have studied the impact of land uses on dissolved organic carbon (DOC) concentrations in 17 Georgia Piedmont headwater streams since January 2001. We classified the w...

  17. Carbon nanotube-based organic light emitting diodes

    NASA Astrophysics Data System (ADS)

    Bansal, Malti; Srivastava, Ritu; Lal, C.; Kamalasanan, M. N.; Tanwar, L. S.

    2009-11-01

    Carbon nanotubes; revolutionary and fascinating from the materials point of view and exceedingly sensational from a research point of view; are standing today at the threshold between inorganic electronics and organic electronics and posing a serious challenge to the big daddies of these two domains in electronics i.e., silicon and indium tin oxide (ITO). In the field of inorganic electronics, carbon nanotubes offer advantages such as high current carrying capacity, ballistic transport, absence of dangling bonds, etc. and on the other hand, in the field of organic electronics, carbon nanotubes offer advantages such as high conductivity, high carrier mobility, optical transparency (in visible and IR spectral ranges), flexibility, robustness, environmental resistance, etc. and hence, they are seriously being considered as contenders to silicon and ITO. This review traces the origin of carbon nanotubes in the field of organic electronics (with emphasis on organic light emitting diodes) and moves on to cover the latest advances in the field of carbon nanotube-based organic light emitting diodes. Topics that are covered within include applications of multi-wall nanotubes and single-wall nanotubes in organic light emitting diodes. Applications of carbon nanotubes as hole-transport layers, as electron-transport layers, as transparent electrodes, etc. in organic light emitting diodes are discussed and the daunting challenges facing this progressive field today are brought into the limelight.

  18. The Transport Properties of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  19. The transport properties of activated carbon fibers

    SciTech Connect

    di Vittorio, S.L. . Dept. of Materials Science and Engineering); Dresselhaus, M.S. . Dept. of Electrical Engineering and Computer Science Massachusetts Inst. of Tech., Cambridge, MA . Dept. of Physics); Endo, M. . Dept. of Electrical Engineering); Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons. 19 refs., 4 figs.

  20. A reduced organic carbon component in martian basalts.

    PubMed

    Steele, A; McCubbin, F M; Fries, M; Kater, L; Boctor, N Z; Fogel, M L; Conrad, P G; Glamoclija, M; Spencer, M; Morrow, A L; Hammond, M R; Zare, R N; Vicenzi, E P; Siljeström, S; Bowden, R; Herd, C D K; Mysen, B O; Shirey, S B; Amundsen, H E F; Treiman, A H; Bullock, E S; Jull, A J T

    2012-07-13

    The source and nature of carbon on Mars have been a subject of intense speculation. We report the results of confocal Raman imaging spectroscopy on 11 martian meteorites, spanning about 4.2 billion years of martian history. Ten of the meteorites contain abiotic macromolecular carbon (MMC) phases detected in association with small oxide grains included within high-temperature minerals. Polycyclic aromatic hydrocarbons were detected along with MMC phases in Dar al Gani 476. The association of organic carbon within magmatic minerals indicates that martian magmas favored precipitation of reduced carbon species during crystallization. The ubiquitous distribution of abiotic organic carbon in martian igneous rocks is important for understanding the martian carbon cycle and has implications for future missions to detect possible past martian life. PMID:22628557

  1. ACTIVATED CARBON FROM LIGNITE FOR WATER TREATMENT

    SciTech Connect

    Edwin S. Olson; Daniel J. Stepan

    2000-07-01

    High concentrations of humate in surface water result in the formation of excess amounts of chlorinated byproducts during disinfection treatment. These precursors can be removed in water treatment prior to disinfection using powdered activated carbon. In the interest of developing a more cost-effective method for removal of humates in surface water, a comparison of the activities of carbons prepared from North Dakota lignites with those of commercial carbons was conducted. Previous studies indicated that a commercial carbon prepared from Texas lignite (Darco HDB) was superior to those prepared from bituminous coals for water treatment. That the high alkali content of North Dakota lignites would result in favorable adsorptive properties for the very large humate molecules was hypothesized, owing to the formation of larger pores during activation. Since no standard humate test has been previously developed, initial adsorption testing was performed using smaller dye molecules with various types of ionic character. With the cationic dye, methylene blue, a carbon prepared from a high-sodium lignite (HSKRC) adsorbed more dye than the Darco HDB. The carbon from the low-sodium lignite was much inferior. With another cationic dye, malachite green, the Darco HDB was slightly better. With anionic dyes, methyl red and azocarmine-B, the results for the HSKRC and Darco HDB were comparable. A humate test was developed using Aldrich humic acid. The HSKRC and the Darco HDB gave equally high adsorption capacities for the humate (138 mg/g), consistent with the similarities observed in earlier tests. A carbon prepared from a high-sodium lignite from a different mine showed an outstanding improvement (201 mg/g). The carbons prepared from the low-sodium lignites from both mines showed poor adsorption capacities for humate. Adsorption isotherms were performed for the set of activated carbons in the humate system. These exhibited a complex behavior interpreted as resulting from two types

  2. Potential enzyme activities in cryoturbated organic matter of arctic soils

    NASA Astrophysics Data System (ADS)

    Schnecker, J.; Wild, B.; Rusalimova, O.; Mikutta, R.; Guggenberger, G.; Richter, A.

    2012-12-01

    An estimated 581 Gt organic carbon is stored in arctic soils that are affected by cryoturbtion, more than in today's atmosphere (450 Gt). The high amount of organic carbon is, amongst other factors, due to topsoil organic matter (OM) that has been subducted by freeze-thaw processes. This cryoturbated OM is usually hundreds to thousands of years old, while the chemical composition remains largely unaltered. It has therefore been suggested, that the retarded decomposition rates cannot be explained by unfavourable abiotic conditions in deeper soil layers alone. Since decomposition of soil organic material is dependent on extracellular enzymes, we measured potential and actual extracellular enzyme activities in organic topsoil, mineral subsoil and cryoturbated material from three different tundra sites, in Zackenberg (Greenland) and Cherskii (North-East Siberia). In addition we analysed the microbial community structure by PLFAs. Hydrolytic enzyme activities, calculated on a per gram dry mass basis, were higher in organic topsoil horizons than in cryoturbated horizons, which in turn were higher than in mineral horizons. When calculated on per gram carbon basis, the activity of the carbon acquiring enzyme exoglucanase was not significantly different between cryoturbated and topsoil organic horizons in any of the three sites. Oxidative enzymes, i.e. phenoloxidase and peroxidase, responsible for degradation of complex organic substances, showed higher activities in topsoil organic and cryoturbated horizons than in mineral horizons, when calculated per gram dry mass. Specific activities (per g C) however were highest in mineral horizons. We also measured actual cellulase activities (by inhibiting microbial uptake of products and without substrate addition): calculated per g C, the activities were up to ten times as high in organic topsoil compared to cryoturbated and mineral horizons, the latter not being significantly different. The total amount of PLFAs, as a proxy for

  3. Determining carbon-carbon connectivities in natural abundance organic powders using dipolar couplings.

    PubMed

    Dekhil, Myriam; Mollica, Giulia; Bonniot, Tristan Texier; Ziarelli, Fabio; Thureau, Pierre; Viel, Stéphane

    2016-06-30

    We present a solid-state NMR methodology capable of investigating the carbon skeleton of natural abundance organic powders. The methodology is based on the (13)C-(13)C dipolar coupling interaction and allows carbon-carbon connectivities to be unambiguously established for a wide range of organic solids. This methodology is particularly suitable for disordered solids, such as natural or synthetic macromolecules, which cannot be studied using conventional diffraction or NMR techniques. PMID:27319808

  4. Anomalous 13C enrichment in modern marine organic carbon

    USGS Publications Warehouse

    Arthur, M.A.; Dean, W.E.; Claypool, G.E.

    1985-01-01

    Marine organic carbon is heavier isotopically (13C enriched) than most land-plant or terrestrial organic C1. Accordingly, ??13C values of organic C in modern marine sediments are routinely interpreted in terms of the relative proportions of marine and terrestrial sources of the preserved organic matter2,3. When independent geochemical techniques are used to evaluate the source of organic matter in Cretaceous or older rocks, those rocks containing mostly marine organic C are found typically to have lighter (more-negative) ??13C values than rocks containing mostly terrestrial organic C. Here we conclude that marine photosynthesis in mid-Cretaceous and earlier oceans generally resulted in a greater fractionation of C isotopes and produced organic C having lighter ??13C values. Modern marine photosynthesis may be occurring under unusual geological conditions (higher oceanic primary production rates, lower PCO2) that limit dissolved CO2 availability and minimize carbon isotope fractionation4. ?? 1985 Nature Publishing Group.

  5. TOTAL ORGANIC CARBON DETERMINATIONS IN NATURAL AND CONTAMINATED AQUIFER MATERIALS

    EPA Science Inventory

    Quantifying the total organic carbon (TOC) content of soils and aquifer materials is essential for understanding subsurface chemistry during environmental site characterization. ontaminant fate and transport, microbial ecology, and effective treatment methodology are all influenc...

  6. Unimodal response of fish yield to dissolved organic carbon.

    PubMed

    Finstad, Anders G; Helland, Ingeborg P; Ugedal, Ola; Hesthagen, Trygve; Hessen, Dag O

    2014-01-01

    Here, we demonstrate a contrasting effect of terrestrial coloured dissolved organic material on the secondary production of boreal nutrient poor lakes. Using fish yield from standardised brown trout gill-net catches as a proxy, we show a unimodal response of lake secondary productivity to dissolved organic carbon (DOC). This suggests a trade-off between positive and negative effects, where the initial increase may hinge upon several factors such as energy subsidising, screening of UV-radiation or P and N load being associated with organic carbon. The subsequent decline in production with further increase in DOC is likely associated with light limitations of primary production. We also show that shallow lakes switch from positive to negative effects at higher carbon loads than deeper lakes. These results underpin the major role of organic carbon for structuring productivity of boreal lake ecosystems. PMID:24165396

  7. Real World of Industrial Chemistry: Organic Chemicals from Carbon Monoxide.

    ERIC Educational Resources Information Center

    Kolb, Kenneth E.; Kolb, Doris

    1983-01-01

    Carbon Monoxide obtained from coal may serve as the source for a wide variety of organic compounds. Several of these compounds are discussed, including phosgene, benzaldehyde, methanol, formic acid and its derivatives, oxo aldehydes, acrylic acids, and others. Commercial reactions of carbon monoxide are highlighted in a table. (JN)

  8. Biofuel intercropping effects on soil carbon and microbial activity.

    PubMed

    Strickland, Michael S; Leggett, Zakiya H; Sucre, Eric B; Bradford, Mark A

    2015-01-01

    Biofuels will help meet rising demands for energy and, ideally, limit climate change associated with carbon losses from the biosphere to atmosphere. Biofuel management must therefore maximize energy production and maintain ecosystem carbon stocks. Increasingly, there is interest in intercropping biofuels with other crops, partly because biofuel production on arable land might reduce availability and increase the price of food. One intercropping approach involves growing biofuel grasses in forest plantations. Grasses differ from trees in both their organic inputs to soils and microbial associations. These differences are associated with losses of soil carbon when grasses become abundant in forests. We investigated how intercropping switchgrass (Panicum virgalum), a major candidate for cellulosic biomass production, in loblolly pine (Pinus taeda) plantations affects soil carbon, nitrogen, and microbial dynamics. Our design involved four treatments: two pine management regimes where harvest residues (i.e., biomass) were left in place or removed, and two switchgrass regimes where the grass was grown with pine under the same two biomass scenarios (left or removed). Soil variables were measured in four 1-ha replicate plots in the first and second year following switchgrass planting. Under switchgrass intercropping, pools of mineralizable and particulate organic matter carbon were 42% and 33% lower, respectively. These declines translated into a 21% decrease in total soil carbon in the upper 15 cm of the soil profile, during early stand development. The switchgrass effect, however, was isolated to the interbed region where switchgrass is planted. In these regions, switchgrass-induced reductions in soil carbon pools with 29%, 43%, and 24% declines in mineralizable, particulate, and total soil carbon, respectively. Our results support the idea that grass inputs to forests can prime the activity of soil organic carbon degrading microbes, leading to net reductions in stocks

  9. Black carbon and organic matter stabilization in soil

    NASA Astrophysics Data System (ADS)

    Lehmann, J.; Liang, B.; Sohi, S.; Gaunt, J.

    2007-12-01

    Interaction with minerals is key to stabilization of organic matter in soils. Stabilization is commonly perceived to occur due to entrapment in pore spaces, encapsulation within aggregates or interaction with mineral surfaces. Typically only interactions between organic matter and minerals are considered in such a model. Here we demonstrate that black carbon may act very similar to minerals in soil in that it enhances the stabilization of organic matter. Mineralization of added organic matter was slower and incorporation into intra-aggregate fractions more rapid in the presence of black carbon. Added double-labeled organic matter was recovered in fractions with high amounts of black carbon. Synchrotron-based near-edge x-ray fine structure (NEXAFS) spectroscopy coupled to scanning transmission x-ray microscopy (STXM) suggested a possible interaction of microorganisms with black carbon surfaces and metabolization of residues. These findings suggest a conceptual model that includes carbon-carbon interactions and by-passing for more rapid stabilization of litter into what is commonly interpreted as stable carbon pools.

  10. Maturation of organic matter during experimental simulation of carbonate diagenesis

    SciTech Connect

    Ferguson, J.; Bush, P.R.; Clarke, B.A. )

    1989-09-01

    An earlier investigation involving the simulation of the early stages of diagenesis of carbonate ooids has been extended to include skeletal carbonates and carbonate mud. The experiments, lasting up to 70 days at elevated hydrostatic pressure and temperatures of 180{degree}-210{degree}C, used natural sea water and recent calcitic and aragonitic carbonate materials collected from Florida Bay and the Bahamas. The results give insight into the processes of maturation and diagenesis of the organic and inorganic fractions. Analysis of the organic fraction, both before and after the experiments, gives indicates of possible pathways of maturation during early diagenesis. A small amount of data is also available on the fate of sugars and amino acids in the system. Overall, the experiments closely approximate the natural system. Reactions occurring in the inorganic components are closely allied to those in the organic fraction. Indeed, two of the critical factors in early carbonate diagenesis are the amount and quality of organic matter and the shape, size, and nature of the carbonate grains. Changes in the carbonate fraction taking place during and after the experiments have been deduced by monitoring the pore fluid chemistry and by analyzing the final solid product. These results are discussed briefly and related to changes in the organic phase.

  11. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyen, M.; Lafferty, C.; Kimber, G.

    1996-12-31

    This paper describes the results of research in which novel activated carbons have been examined for their efficacy in water treatment and, specifically, for the adsorption of a common herbicide and wood preservative, sodium pentachlorophenolate. To place this work in context, the introduction will discuss first some of the considerations of using activated carbons for water treatment, and then certain aspects of the authors research that has led to this particular topic.

  12. Carbon Nanotube Composites as Efficient Charge Transport Media in Organic Optoelectronic Devices

    NASA Astrophysics Data System (ADS)

    Fournet, Patrick; Coleman, Jonathan N.; O'Brien, Diarmuid F.; Lahr, Bernd; Drury, Anna; McNeill, Christopher R.; Dastoor, Paul C.; Wallace, Gordon G.; Hoerhold, Hans-Heinrich; Blau, Werner J.

    2003-03-01

    Thanks to their cheap processability, organic optoelectronic devices are believed to gradually gain a non-negligible place on the market. However, their performances remain low, mainly because of the poor electron transport in conventional polymers used in such devices. Carbon nanotubes, with a bulk conductivity as high as 10E5 S/m, could therefore be seen as potential candidates to address this important issue. In this work, we have studied the use of a carbon nanotube and polymer composite as an active layer in organic light-emitting diodes and organic photovoltaic devices. Enhanced brightness was achieved using the composite as an electron-transport layer in organic light-emitting diodes, the best efficiency being obtained for those devices with a nanotube content of 1.2 %. Secondly, we have studied the use of the polymer and carbon nanotube composite as the active layer in organic photovoltaic cells. Photocurrents in such devices were greater than that of the cells without carbon nanotubes. It is believed that carbon nanotube composites could act as efficient transport media for charges, which were originally dissociated. This study has demonstrated that carbon nanotubes can be used as functional materials in organic optoelectronic devices and enhance the charge transport, hence the efficiency in such devices.

  13. Structural Evolution of Co-Based Metal Organic Frameworks in Pyrolysis for Synthesis of Core-Shells on Nanosheets: Co@CoOx@Carbon-rGO Composites for Enhanced Hydrogen Generation Activity.

    PubMed

    Xing, Congcong; Liu, Yanyan; Su, Yongheng; Chen, Yinghao; Hao, Shuo; Wu, Xianli; Wang, Xiangyu; Cao, Huaqiang; Li, Baojun

    2016-06-22

    In this article, Co-based metal organic frameworks (MOFs) with two shapes were used as pyrolysis precursor to synthesize multilayer core-shells composites loaded on reduced graphene oxide (rGO) sheets. The core-shell structures were obtained by the formation of cores from metal ions and carbon shells from carbonization of ligands. Controllable oxidation of Co cores to CoOx shells generated multilayer core-shell structures anchored onto the surface of rGO sheets. The N-doped composites were obtained by adding poly vinylpyrrolidone. The multilayer core-shells composites exhibited superior catalytic activity toward hydrogen generation compared to their single layer counterparts. By using the N-doped multilayer composites, high hydrogen generation specific rate of 5560 mL min(-1) gCo(-1) was achieved at room temperature. The rGO sheets in composites improved their structure stability. These catalysts exhibited high stability after used five cycling. This synergistic strategy proposes simple, efficient, and versatile blue-prints for the fabrication of rGO composites from MOFs-based precursors. PMID:27243608

  14. Organic carbon dynamics in the Mediterranean Sea: An integrated study

    NASA Astrophysics Data System (ADS)

    Santinelli, Chiara; SempéRé, Richard; van Wambeke, France; Charriere, Bruno; Seritti, Alfredo

    2012-12-01

    Total (TOC) and dissolved (DOC) organic carbon vertical profiles were analyzed from 11 stations located in various regions of the Mediterranean Sea, together with the distribution of other physical, chemical and biological parameters. TOC showed the highest concentrations (68-83 μM) above the pycnocline, followed by a marked decrease to values of 45-48 μM at 100-200 m. Below 200 m, values of 40-45 μM were observed. The excess TOC and DOC occurring at each station was calculated by subtracting 48 μM from the observed concentrations. The stock of the excess TOC and DOC increased eastward; while surface DOC mineralization rates decreased from 1.5 μM d-1 to 0.26 μM d-1 eastward. The integrated average of the biological parameters in the above-pycnocline layer showed a bacterial production versus particulate primary production (BP/PPP) ratio ranging from 22% in the Ionian Sea (MIO station) to 31% in the Ligurian Sea (Dyfamed station), while bacterial carbon demand versus PPP was higher than 100%, considering a bacterial growth efficiency of both 15% and 30%. The data here reported indicate various scenarios of carbon dynamics. At the stations west of the Sardinian Channel, the microbial loop was very active, and a high flux of carbon to the microbial loop (large bacterial and protist abundance) may be hypothesized, which would result in a low DOC concentration. At the stations east of the Sardinian Channel, no significant longitudinal variation was found in DOC and BP. DOC accumulated at these stations, possibly due to bacteria P-limitation, to DOC chemical composition and/or to the occurrence of different prokaryotic populations with a different ability to consume the available DOC.

  15. Investigation of organic carbon transformation in soils of dominant dissolved organic carbon source zones

    NASA Astrophysics Data System (ADS)

    Pissarello, Anna; Miltner, Anja; Oosterwoud, Marieke; Fleckenstein, Jan; Kästner, Matthias

    2014-05-01

    Over the past 20 years both a decrease in soil organic matter (SOM) and an increase in the dissolved organic carbon (DOC) concentrations in surface water bodies, including drinking water reservoirs, have been recorded in the northern hemisphere. This development has severe consequences for soil fertility and for drinking water purification. As both processes occur simultaneously, we assume that microbial SOM degradation, which transforms SOM into CO2 and DOC, is a possible source of the additional DOC in the surface water. In addition we speculate that both processes are initially triggered by physical mechanisms, resulting in a modification of the organic matter solubility equilibria and thus in higher SOM availability and DOC mobilization. The general hypothesis of the study is therefore that SOM loss and DOC increase are combined consequences of enhanced microbial degradation of SOM and that this is a result of climate variations and global change, e.g. the increase of the temperature, the alteration of the water regime (i.e. increase of the frequency of drying and rewetting cycles and a higher number of heavy rain events), but also the decrease of the atmospheric acid deposition resulting in an increase of soil pH values. The general goal of the study is the identification of the dominant processes and controlling factors involved in soil microbial carbon turnover and mobilization of DOC in soils from catchment areas that contribute DOC to the receiving waters and the downstream Rappbode reservoir, which showed a pronounced increase in DOC concentration in recent years. This reservoir is the source of drinking water for about one million people in northern Germany. Preliminary screening experiments, consisting of 65-day soil batch incubation experiments, have been conducted in order to select the parameters (and the parameter ranges) of relevance for further in-depth experiments. During the experiments, different soil systems were exposed to different

  16. 28 CFR 551.34 - Organization activities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 2 2011-07-01 2011-07-01 false Organization activities. 551.34 Section 551.34 Judicial Administration BUREAU OF PRISONS, DEPARTMENT OF JUSTICE INSTITUTIONAL MANAGEMENT MISCELLANEOUS Inmate Organizations § 551.34 Organization activities. (a) An officer of the inmate...

  17. Activated Carbons From Grape Seeds By Chemical Activation With Potassium Carbonate And Potassium Hydroxide

    NASA Astrophysics Data System (ADS)

    Okman, Irem; Karagöz, Selhan; Tay, Turgay; Erdem, Murat

    2014-02-01

    Activated carbons were produced from grape seed using either potassium carbonate (K2CO3) or potassium hydroxide (KOH). The carbonization experiments were accomplished at 600 and 800 °C. The effects of the experimental conditions (i.e., type of activation reagents, reagent concentrations, and carbonization temperatures) on the yields and the properties of these activated carbons were analyzed under identical conditions. An increase in the temperature at the same concentrations for both K2CO3 and KOH led to a decrease in the yields of the activated carbons. The lowest activated carbon yields were obtained at 800 °C at the highest reagent concentration (100 wt%) for both K2CO3 and KOH. The activated carbon with the highest surface area of 1238 m2g-1 was obtained at 800 °C in K2CO3 concentration of 50 wt% while KOH produced the activated carbon with the highest surface area of 1222 m2g-1 in a concentration of 25wt% at 800 °C. The obtained activated carbons were mainly microporous.

  18. Carbon isotopic studies of organic matter in Precambrian rocks.

    NASA Technical Reports Server (NTRS)

    Oehler, D. Z.; Schopf, J. W.; Kvenvolden, K. A.

    1972-01-01

    A survey has been undertaken of the carbon composition of the total organic fraction of a suite of Precambrian sediments to detect isotopic trends possibly correlative with early evolutionary events. Early Precambrian cherts of the Fig Tree and upper and middle Onverwacht groups of South Africa were examined for this purpose. Reduced carbon in these cherts was found to be isotopically similar to photosynthetically produced organic matter of younger geological age. Reduced carbon in lower Onverwacht cherts was found to be anomalously heavy; it is suggested that this discontinuity may reflect a major event in biological evolution.

  19. Microbial Breakdown of Organic Carbon in the Diverse Sediments of Guaymas Basin

    NASA Astrophysics Data System (ADS)

    Hoarfrost, A.; Snider, R.; Arnosti, C.

    2015-12-01

    Guaymas Basin is characterized by sediments under conditions ranging from hemipelagic to hydrothermal. This wide range in geochemical contexts results in diverse microbial communities that may have varying abilities to access organic matter. We can address these functional differences by comparing enzyme activities initializing the breakdown of organic matter across these sediment types; however, previous direct measurements of the extracellular hydrolysis of complex organic carbon in sediments are sparse. We measured this first step of heterotrophic processing of organic matter in sediments at 5-10cm and 55-60cm depth from a wide range of environmental settings in Guaymas Basin. Sediment sources included sulfidic seeps on the Sonora Margin, hemipelagic ridge flank sediments, and hydrothermically altered Sonora Margin sediments bordering a methane seep site. Hydrolysis of organic substrates varied by depth and by sediment source, but despite high energy potential and organic carbon load in sulfidic sediments, activity was not highest where hydrothermal influence was highest. These results suggest that heterotrophic breakdown of organic carbon in Guaymas Basin sediments may be sensitive to factors including varying composition of organic carbon available in different sediment types, or differences in microbial community capacities to access specific organic substrates.

  20. Carbon dioxide capturing technologies: a review focusing on metal organic framework materials (MOFs).

    PubMed

    Sabouni, Rana; Kazemian, Hossein; Rohani, Sohrab

    2014-04-01

    In this study, a relevant literature has been reviewed focusing on the carbon dioxide capture technologies in general, such as amine-based absorption as conventional carbon dioxide capturing technology, aqueous ammonia-based absorption, membranes, and adsorption material (e.g., zeolites, and activated carbons). In more details, metal organic frameworks (MOFs) as new emerging technologies for carbon dioxide adsorption are discussed. The MOFs section is intended to provide a comprehensive overview of MOFs including material characteristics and synthesis, structural features, CO2 adsorption capacity, heat of adsorption and selectivity of CO2. PMID:24338107

  1. Microwave-assisted regeneration of activated carbon.

    PubMed

    Foo, K Y; Hameed, B H

    2012-09-01

    Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons. PMID:22728787

  2. Antimicrobial Activity of Carbon-Based Nanoparticles

    PubMed Central

    Maleki Dizaj, Solmaz; Mennati, Afsaneh; Jafari, Samira; Khezri, Khadejeh; Adibkia, Khosro

    2015-01-01

    Due to the vast and inappropriate use of the antibiotics, microorganisms have begun to develop resistance to the commonly used antimicrobial agents. So therefore, development of the new and effective antimicrobial agents seems to be necessary. According to some recent reports, carbon-based nanomaterials such as fullerenes, carbon nanotubes (CNTs) (especially single-walled carbon nanotubes (SWCNTs)) and graphene oxide (GO) nanoparticles show potent antimicrobial properties. In present review, we have briefly summarized the antimicrobial activity of carbon-based nanoparticles together with their mechanism of action. Reviewed literature show that the size of carbon nanoparticles plays an important role in the inactivation of the microorganisms. As major mechanism, direct contact of microorganisms with carbon nanostructures seriously affects their cellular membrane integrity, metabolic processes and morphology. The antimicrobial activity of carbon-based nanostructures may interestingly be investigated in the near future owing to their high surface/volume ratio, large inner volume and other unique chemical and physical properties. In addition, application of functionalized carbon nanomaterials as carriers for the ordinary antibiotics possibly will decrease the associated resistance, enhance their bioavailability and provide their targeted delivery. PMID:25789215

  3. Interrelationships of organic carbon and submarine sediment geotechnical properties

    SciTech Connect

    Bennett, R.H.; Lehman, L.; Hulbert, M.H.; Harvey, G.R.; Bush, S.A.; Forde, E.B.; Crews, P.; Sawyer, W.B.

    1985-01-01

    Total organic carbon content (TOC) and selected geotechnical properties we measured in submarine sediments of the US central east coast and the Mississippi Delta. TOC values in the near-surface Delta sediments were approximately 1% (dry weight). TOC in surficial sediments from the US east coast outer continental shelf, upper slope, and upper rise was generally less than 1%, but between the upper slope and the upper rise, values ranged from 1 to 3% and exceeded 3% in patches associated with Norfolk and Washington Canyons. TOC displayed positive linear correlations with water content, liquid limit, plastic limit, plasticity index, and the amount (percent) of fine-grained material. Nevertheless, there appeared to be no strong dependence of geotechnical properties on TOC in these sediments. This was in accord with previously reported studies on terrestrial soils with TOC values of less than 5%. Carbohydrate content was strongly correlated with water content and plasticity index, suggesting that measurement of individual components of the organic material may provide more sensitive indications of the effects of organics on geotechnical properties than measurement of bulk TOC. Selected geotechnical properties and TOC content of US continental margin surficial sediments displayed regional trends related to water depth and morphological setting. These trends are probably related to recent biological, sedimentological, and oceanographic processes active on the outer shelf, slope, and rise.

  4. COSOLVENT EFFECTS ON ORGANIC CHEMICAL PARTITIONING TO SEDIMENT ORGANIC CARBON

    EPA Science Inventory

    Sorption-desorption hysteresis, slow desorption kinetics and resultant bioavailability, and other nonideal phenomena have been attributed to the differing sorptive characteristics of the natural organic polymers associated with soils and sediments. The objectives of this study we...

  5. Activated coconut shell charcoal carbon using chemical-physical activation

    NASA Astrophysics Data System (ADS)

    Budi, Esmar; Umiatin, Nasbey, Hadi; Bintoro, Ridho Akbar; Wulandari, Futri; Erlina

    2016-02-01

    The use of activated carbon from natural material such as coconut shell charcoal as metal absorbance of the wastewater is a new trend. The activation of coconut shell charcoal carbon by using chemical-physical activation has been investigated. Coconut shell was pyrolized in kiln at temperature about 75 - 150 °C for about 6 hours in producing charcoal. The charcoal as the sample was shieved into milimeter sized granule particle and chemically activated by immersing in various concentration of HCl, H3PO4, KOH and NaOH solutions. The samples then was physically activated using horizontal furnace at 400°C for 1 hours in argon gas environment with flow rate of 200 kg/m3. The surface morphology and carbon content of activated carbon were characterized by using SEM/EDS. The result shows that the pores of activated carbon are openned wider as the chemical activator concentration is increased due to an excessive chemical attack. However, the pores tend to be closed as further increasing in chemical activator concentration due to carbon collapsing.

  6. Organic farming enhances soil carbon and its benefits

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increasing soil carbon through systematic agricultural practices provides an array of societal and farmer/producer benefits. Organic methods have been utilized for over 6000 years to conserve soil, water, energy, and biological resources. Many of the benefits of organic technologies identified in ...

  7. Microbial Contribution to Organic Carbon Sequestration in Mineral Soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil productivity and sustainability are dependent on soil organic matter (SOM). Our understanding on how organic inputs to soil from microbial processes become converted to SOM is still limited. This study aims to understand how microbes affect carbon (C) sequestration and the formation of recalcit...

  8. [The organic carbon--issues of hygienic regulation and harmonization].

    PubMed

    Kuz'mina, E A; Kuznetsov, E O; Smagina, N V; Slyshkina, T V; Akramov, R L; Brusnitsina, L A; Nitsak, G B; Nikonova, S V

    2013-01-01

    This study is devoted to the investigation of possibility to use the total organic carbon as regulated index in drinking water as well as to the issues of hygienic regulation and harmonizing this index with the standards of other countries. Basing on the results of 3 years lasting investigation carried out by Municipal Unitary Enterprise "Vodokanal" of Yekaterinburg city permits to propose as the most informative and reliable index of the presence of organic substances in drinking water the content of total organic carbon in comparison with currently regulated permanganate oxidability, chemical and biochemical oxygen consumption. PMID:24624824

  9. Environmental Controls of Soil Organic Carbon in Soils Across Amazonia

    NASA Astrophysics Data System (ADS)

    Quesada, Carlos Alberto; Paz, Claudia; Phillips, Oliver; Nonato Araujo Filho, Raimundo; Lloyd, Jon

    2015-04-01

    (kaolinitic) and thus the clay plus silt fraction was the best correlate for SOC but with crystalline iron oxides (dithionite-citrate minus ammonium oxalate - oxalic acid extractable iron) being also correlated to SOC in these soils (R2 = 0.74). Most of SOC in these soils was found on the clay+silt fraction and in stable, clay rich aggregates. However, SOC of high activity clays and other less weathered soils such as Alisols, Cambisols and Plinthosols showed no correlation with particle size or iron oxides, being mostly stabilized by aluminium complexes. We found SOC of these soils to be better explained by a three way interaction among soil pH, carbon quality and dithionite-citrate extractable Al (R2 = 0.85). Consistent with this observation, SOC in the less weathered soils was mostly found in the colloidal fraction (75%). SOC of Podzols and Arenosols on the other hand had only a small but significant influence from their clay plus silt fraction (R2 = 0.31), with particulate organic matter accounting for most of its SOC.

  10. Carbon-Based Supercapacitors Produced by Activation of Graphene

    SciTech Connect

    Zhu, Y.; Su, D.; Murali, S.; Stoller, M.D.; Ganesh, K.J.; Cai, W.; Ferreira, P.J.; Pirkle, A.; Wallace, R.M.; Cychosz, K.A., Thommes, M.; Stach, E.A.; Ruoff, R.S.

    2011-06-24

    Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp{sup 2}-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

  11. Carbon-based Supercapacitors Produced by Activation of Graphene

    SciTech Connect

    Y Zhu; S Murali; M Stoller; K Ganesh; W Cai; P Ferreira; A Pirkle; R Wallace; K Cychosz; et al.

    2011-12-31

    Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp{sup 2}-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

  12. Coupled ocean-atmosphere loss of marine refractory dissolved organic carbon

    NASA Astrophysics Data System (ADS)

    Kieber, David J.; Keene, William C.; Frossard, Amanda A.; Long, Michael S.; Maben, John R.; Russell, Lynn M.; Kinsey, Joanna D.; Tyssebotn, Inger Marie B.; Quinn, Patricia K.; Bates, Timothy S.

    2016-03-01

    The oceans hold a massive quantity of organic carbon, nearly all of which is dissolved and more than 95% is refractory, cycling through the oceans several times before complete removal. The vast reservoir of refractory dissolved organic carbon (RDOC) is a critical component of the global carbon cycle that is relevant to our understanding of fundamental marine biogeochemical processes and the role of the oceans in climate change with respect to long-term storage and sequestration of atmospheric carbon dioxide. Here we show that RDOC includes surface-active organic matter that can be incorporated into primary marine aerosol produced by bursting bubbles at the sea surface. We propose that this process will deliver RDOC from the sea surface to the atmosphere wherein its photochemical oxidation corresponds to a potentially important and hitherto unknown removal mechanism for marine RDOC.

  13. Organic carbon leaching behavior from incinerator bottom ash.

    PubMed

    Guimaraes, A L; Okuda, T; Nishijima, W; Okada, M

    2006-09-21

    The understanding of the leaching behavior of organic carbon from incinerator bottom ash is an important aspect for the control of organic carbon emissions from landfills in order to minimize their potential risk to the environment. The leaching behavior of organic carbon from incinerator bottom ash samples, obtained from two different solid waste sources, as well as the effects of calcium (Ca) on organic carbon (DOC) leaching associated with pH were therefore investigated in this paper. The effect of pH on the leaching of DOC and other major elements from bottom ash was ascertained through pH-stat leaching experiments. Column leaching experiments were carried out to evaluate the dependence of the leached amount of DOC on Ca leaching. It was found that the bottom ash produced by incineration of municipal solid waste (MSW) was composed of two DOC fractions: DOC leached independent (fraction I) of Ca leaching, observed at alkaline-neutral pH, and DOC leached dependent (fraction II) on Ca leaching, observed at acid pH. However, the bottom ash produced by incineration of industrial solid waste (ISW) was composed of only DOC fraction I. The addition of calcium oxide during incineration and the differences in the paper to plastic ratio in the physical composition of the solid wastes incinerated would explain the distinct organic carbon leaching behaviors of bottom ash samples. PMID:16675109

  14. Potential Influence of Perchlorate on Organic Carbon in Martian Regolith

    NASA Astrophysics Data System (ADS)

    Oze, C.; Vithanage, M. S.; Kumarathilaka, P. R.; Indraratne, S.; Horton, T. W.

    2014-12-01

    Perchlorate is a strong oxidizer present at elevated concentrations in surface martian regolith. Chemical and isotopic modification of potential organic carbon with perchlorate in martian regolith during H2O(l) interactions is unknown. Here we assess the relationship between martian levels of perchlorate and organic carbon present in life harbouring geologic material from Earth. These materials represent chemical (i.e., processed serpentine soils from Sri Lanka) and temperature (i.e., hydrothermal jarosite/goethite deposit from White Island, New Zealand) extremes to where life exists on Earth. Preliminary evidence demonstrates that organic carbon decreases and δ13C values are modified for ultramafic sediment in both perchlorate kinetic and incubation experiments. In hydrothermal jarosite/goethite with microbial communities present, total and organic carbon is maintained and little modification in δ13C values is apparent. These preliminary results suggest that surface hydrothermal deposits with mineralogically 'protected' organic carbon are preferable sites to assess the potential of life on Mars.

  15. Organics on Titan : Carbon Rings and Carbon Cycles (Invited)

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.

    2010-12-01

    The photochemical conversion of methane into heavier organics which would cover Titan’s surface has been a principal motif of Titan science for the last 4 decades. Broadly, this picture has held up against Cassini observations, but organics on Titan turn out to have some surprising characteristics. First, the surface deposits of organics are segregated into at least two distinct major reservoirs - equatorial dune sands and polar seas. Second, the rich array of compounds detected as ions and molecules even 1000km above Titan’s surface has proven much more complex than expected, including two-ring anthracene and compounds with m/z>1000. Radar and near-IR mapping shows that Titan’s vast dunefields, covering >10% of Titan’s surface, contain ~0.3 million km^3 of material. This material is optically dark and has a low dielectric constant, consistent with organic particulates. Furthermore, the dunes are associated with a near-IR spectral signature attributed to aromatic compounds such as benzene, which has been sampled in surprising abundance in Titan’s upper atmosphere. The polar seas and lakes of ethane (and presumably at least some methane) may have a rather lower total volume than the dune sands, and indeed may contain little more, if any, methane than the atmosphere itself. The striking preponderance of liquid deposits in the north, notably the 500- and 1000-km Ligeia and Kraken, contrasts with the apparently shallow and shrinking Ontario Lacus in the south, and perhaps attests to volatile migration on astronomical (Croll-Milankovich) timescales as well as seasonal methane transport. Against this appealing picture, many questions remain. What is the detailed composition of the seas, and can chemistry in a nonpolar solvent yield compounds of astrobiological interest ? Are there ‘groundwater’ reservoirs of methane seething beneath the surface, perhaps venting to form otherwise improbable equatorial clouds? And what role, if any, do clathrates play today

  16. Stream bed organic carbon and biotic integrity.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Allochthonous organic matter provides a basis for some stream ecosystems. Channel incision, which is a common result of anthropogenic impacts on watersheds and stream channels, may deplete stream bed C stores due to erosion, less frequent hydrologic exchanges between stream and floodplain, and remov...

  17. Soil organic carbon sequestration with conservation management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The southeastern USA has approximately 111 million acres (45 Mha) in agricultural production. This extensive land resource has the potential to sequester soil organic C (SOC), especially following historical conversion of land, first from native forest to intensively cultivated cropland and more re...

  18. Microbial primary production on an Arctic glacier is insignificant in comparison with allochthonous organic carbon input.

    PubMed

    Stibal, Marek; Tranter, Martyn; Benning, Liane G; Rehák, Josef

    2008-08-01

    Cryoconite holes are unique freshwater environments on glacier surfaces, formed when solar-heated dark debris melts down into the ice. Active photoautotrophic microorganisms are abundant within the holes and fix inorganic carbon due to the availability of liquid water and solar radiation. Cryoconite holes are potentially important sources of organic carbon to the glacial ecosystem, but the relative magnitudes of autochthonous microbial primary production and wind-borne allochthonous organic matter brought are unknown. Here, we compare an estimate of annual microbial primary production in 2006 on Werenskioldbreen, a Svalbard glacier, with the organic carbon content of cryoconite debris. There is a great disparity between annual primary production (4.3 mug C g(-1) year(-1)) and the high content of organic carbon within the debris (1.7-4.5%, equivalent to 8500-22 000 mug C g(-1) debris). Long-term accumulation of autochthonous organic matter is considered unlikely due to ablation dynamics and the surface hydrology of the glacier. Rather, it is more likely that the majority of the organic matter on Werenskioldbreen is allochthonous. Hence, although glacier surfaces can be a significant source of organic carbon for glacial environments on Svalbard, they may be reservoirs rather than oases of high productivity. PMID:18430008

  19. Highly Robust Hybrid Photocatalyst for Carbon Dioxide Reduction: Tuning and Optimization of Catalytic Activities of Dye/TiO2/Re(I) Organic-Inorganic Ternary Systems.

    PubMed

    Won, Dong-Il; Lee, Jong-Su; Ji, Jung-Min; Jung, Won-Jo; Son, Ho-Jin; Pac, Chyongjin; Kang, Sang Ook

    2015-10-28

    Herein we report a detailed investigation of a highly robust hybrid system (sensitizer/TiO2/catalyst) for the visible-light reduction of CO2 to CO; the system comprises 5'-(4-[bis(4-methoxymethylphenyl)amino]phenyl-2,2'-dithiophen-5-yl)cyanoacrylic acid as the sensitizer and (4,4'-bis(methylphosphonic acid)-2,2'-bipyridine)Re(I)(CO)3Cl as the catalyst, both of which have been anchored on three different types of TiO2 particles (s-TiO2, h-TiO2, d-TiO2). It was found that remarkable enhancements in the CO2 conversion activity of the hybrid photocatalytic system can be achieved by addition of water or such other additives as Li(+), Na(+), and TEOA. The photocatalytic CO2 reduction efficiency was enhanced by approximately 300% upon addition of 3% (v/v) H2O, giving a turnover number of ≥570 for 30 h. A series of Mott-Schottky (MS) analyses on nanoparticle TiO2 films demonstrated that the flat-band potential (V(fb)) of TiO2 in dry DMF is substantially negative but positively shifts to considerable degrees in the presence of water or Li(+), indicating that the enhancement effects of the additives on the catalytic activity should mainly arise from optimal alignment of the TiO2 V(fb) with respect to the excited-state oxidation potential of the sensitizer and the reduction potential of the catalyst in our ternary system. The present results confirm that the TiO2 semiconductor in our heterogeneous hybrid system is an essential component that can effectively work as an electron reservoir and as an electron transporting mediator to play essential roles in the persistent photocatalysis activity of the hybrid system in the selective reduction of CO2 to CO. PMID:26456369

  20. Microcystin-LR Adsorption by Activated Carbon.

    PubMed

    Pendleton, Phillip; Schumann, Russell; Wong, Shiaw Hui

    2001-08-01

    We use a selection of wood-based and coconut-based activated carbons to investigate the factors controlling the removal of the hepatotoxin microcystin-LR (m-LR) from aqueous solutions. The wood carbons contain both micropores and mesopores. The coconut carbons contain micropores only. Confirming previously published observations, we also find that the wood-based carbons adsorb more microcystin than the coconut-based carbons. From a combination of a judicious modification of a wood-based carbon's surface chemistry and of the solution chemistry, we demonstrate that both surface and solution chemistry play minor roles in the adsorption process, with the adsorbent surface chemistry exhibiting less influence than the solution chemistry. Conformational changes at low solution pH probably contribute to the observed increase in adsorption by both classes of adsorbent. At the solution pH of 2.5, the coconut-based carbons exhibit a 400% increased affinity for m-LR compared with 100% increases for the wood-based carbons. In an analysis of the thermodynamics of adsorption, using multiple temperature adsorption chromatography methods, we indicate that m-LR adsorption is an entropy-driven process for each of the carbons, except the most hydrophilic and mesoporous carbon, B1. In this case, exothermic enthalpy contributions to adsorption also exist. From our overall observations, since m-LR contains molecular dimensions in the secondary micropore width range, we demonstrate that it is important to consider both the secondary micropore and the mesopore volumes for the adsorption of m-LR from aqueous solutions. Copyright 2001 Academic Press. PMID:11446779

  1. Chemistry of organic carbon in soil with relationship to the global carbon cycle

    SciTech Connect

    Post, W.M. III

    1988-01-01

    Various ecosystem disturbances alter the balances between production of organic matter and its decomposition and therefore change the amount of carbon in soil. The most severe perturbation is conversion of natural vegetation to cultivated crops. Conversion of natural vegetation to cultivated crops results in a lowered input of slowly decomposing material which causes a reduction in overall carbon levels. Disruption of soil matrix structure by cultivation leads to lowered physical protection of organic matter resulting in an increased net mineralization rate of soil carbon. Climate change is another perturbation that affects the amount and composition of plant production, litter inputs, and decomposition regimes but does not affect soil structure directly. Nevertheless, large changes in soil carbon storage are probable with anticipated CO2 induced climate change, particularly in northern latitudes where anticipated climate change will be greatest (MacCracken and Luther 1985) and large amounts of soil organic matter are found. It is impossible, given the current state of knowledge of soil organic matter processes and transformations to develop detailed process models of soil carbon dynamics. Largely phenomenological models appear to be developing into predictive tools for understanding the role of soil organic matter in the global carbon cycle. In particular, these models will be useful in quantifying soil carbon changes due to human land-use and to anticipated global climate and vegetation changes. 47 refs., 7 figs., 2 tabs.

  2. A novel activated carbon for supercapacitors

    SciTech Connect

    Shen, Haijie; Liu, Enhui; Xiang, Xiaoxia; Huang, Zhengzheng; Tian, Yingying; Wu, Yuhu; Wu, Zhilian; Xie, Hui

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer A novel activated carbon was prepared from phenol-melamine-formaldehyde resin. Black-Right-Pointing-Pointer The carbon has large surface area with microporous, and high heteroatom content. Black-Right-Pointing-Pointer Heteroatom-containing functional groups can improve the pseudo-capacitance. Black-Right-Pointing-Pointer Physical and chemical properties lead to the good electrochemical properties. -- Abstract: A novel activated carbon has been prepared by simple carbonization and activation of phenol-melamine-formaldehyde resin which is synthesized by the condensation polymerization method. The morphology, thermal stability, surface area, elemental composition and surface chemical composition of samples have been investigated by scanning electron microscope, thermogravimetry and differential thermal analysis, Brunauer-Emmett-Teller measurement, elemental analysis and X-ray photoelectron spectroscopy, respectively. Electrochemical properties have been studied by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 6 mol L{sup -1} potassium hydroxide. The activated carbon shows good capacitive behavior and the specific capacitance is up to 210 F g{sup -1}, which indicates that it may be a promising candidate for supercapacitors.

  3. Maximum organic carbon limits at different melter feed rates (U)

    SciTech Connect

    Choi, A.S.

    1995-12-31

    This report documents the results of a study to assess the impact of varying melter feed rates on the maximum total organic carbon (TOC) limits allowable in the DWPF melter feed. Topics discussed include: carbon content; feed rate; feed composition; melter vapor space temperature; combustion and dilution air; off-gas surges; earlier work on maximum TOC; overview of models; and the results of the work completed.

  4. One carbon metabolism in anaerobic bacteria: Regulation of carbon and electron flow during organic acid production

    SciTech Connect

    Zeikus, J.G.; Jain, M.

    1993-12-31

    The project deals with understanding the fundamental biochemical mechanisms that physiologically control and regulate carbon and electron flow in anaerobic chemosynthetic bacteria that couple metabolism of single carbon compounds and hydrogen to the production of organic acids (formic, acetic, butyric, and succinic) or methane. The authors compare the regulation of carbon dioxide and hydrogen metabolism by fermentation, enzyme, and electron carrier analysis using Butyribacterium methylotrophicum, Anaeroblospirillum succiniciproducens, Methanosarcina barkeri, and a newly isolated tri-culture composed of a syntrophic butyrate degrader strain IB, Methanosarcina mazei and Methanobacterium formicicum as model systems. To understand the regulation of hydrogen metabolism during butyrate production or acetate degradation, hydrogenase activity in B. methylotrophicum or M. barkeri is measured in relation to growth substrate and pH; hydrogenase is purified and characterized to investigate number of hydrogenases; their localization and functions; and, their sequences are determined. To understand the mechanism for catabolic CO{sub 2} fixation to succinate the PEP carboxykinase enzyme and gene of A. succiniciproducens are purified and characterized. Genetically engineered strains of Escherichia coli containing the phosphoenolpyruvate (PEP) carboxykinase gene are examined for their ability to produce succinate in high yield. To understand the mechanism of fatty acid degradation by syntrophic acetogens during mixed culture methanogenesis formate and hydrogen production are characterized by radio tracer studies. It is intended that these studies provide strategies to improve anaerobic fermentations used for the production of organic acids or methane and, new basic understanding on catabolic CO{sub 2} fixation mechanisms and on the function of hydrogenase in anaerobic bacteria.

  5. Raman spectroscopy: Caution when interpreting organic carbon from oxidising environments

    NASA Astrophysics Data System (ADS)

    Brolly, Connor; Parnell, John; Bowden, Stephen

    2016-02-01

    Oxidation on Mars is primarily caused by the high influx of cosmic and solar radiation which interacts with the Martian surface. The evidence of this can be seen in the ubiquitous red colouration of the Martian sediment. This radiation will destroy most signals of life in the top few metres of the Martian surface. If organic carbon (one of the building blocks of life) is present within the accessible Martian sediments, it is very likely that it will have experienced some oxidation. ESA's ExoMars mission set to fly in 2018, has on board a miniaturised Raman spectrometer. As Raman spectroscopy is sensitive to carbonaceous material and will be primarily used to characterise organics, it is essential that the effect oxidation has on the Raman carbon signal is assessed. Oxidised carbonaceous shales were analysed using Raman spectroscopy to assess this issue. Results show that haematite has a band which occurs in the same frequency as the carbon D band, which cannot be distinguished from each other. This can lead to a misidentification of the carbon D band and a misinterpretation of the carbon order. Consequently, caution must be taken when applying Raman spectroscopy for organic carbon analysis in oxidised terrestrial and extraterrestrial environments, including on Mars.

  6. Fluvial organic carbon losses from a Bornean blackwater river

    NASA Astrophysics Data System (ADS)

    Moore, S.; Gauci, V.; Evans, C. D.; Page, S. E.

    2010-11-01

    The transport of carbon from terrestrial ecosystems such as peatlands into rivers and out to the oceans plays an important role in the carbon cycle because it provides a link between the terrestrial and marine carbon cycles. Concentrations of dissolved organic carbon (DOC) and particulate organic carbon (POC) were analysed from the source to the mouth of the River Sebangau in Central Kalimantan, Indonesia during the dry and wet seasons in 2008/2009 and an annual total organic carbon (TOC) flux estimated. DOC concentrations were higher and POC concentrations lower in the wet season compared to the dry season. As seen in other tropical blackwater rivers, DOC concentration is consistently around 10 times greater than POC concentration. We estimate the annual TOC flux discharged to the Java Sea to be 0.46 Tg year-1 comprising of 93% (0.43 Tg) DOC and 7% (0.03 Tg) POC. This equates to a fluvial TOC loss flux per unit area over the entire Sebangau catchment of 88 g C m-2 yr-1. When extrapolating this TOC loss flux to the peat covered area of Indonesia (206 950 km2), we estimate a TOC loss of 18.2 Tg C yr-1 or ~10% of current estimates of the global annual riverine DOC discharge into the ocean.

  7. Fluvial organic carbon losses from a Bornean blackwater river

    NASA Astrophysics Data System (ADS)

    Moore, S.; Gauci, V.; Page, S.; Evans, C.; Limin, S.

    2010-12-01

    The transport of carbon from terrestrial ecosystems such as peatlands into rivers and out to the oceans plays an important role in the carbon cycle because it provides a link between the terrestrial and marine carbon cycles. Concentrations of dissolved organic carbon (DOC) and particulate organic carbon (POC) were analysed from the source to the mouth of the River Sebangau in Central Kalimantan, Indonesia during the dry and wet seasons in 2008/2009 and an annual total organic carbon (TOC) flux estimated. DOC concentrations were higher and POC concentrations lower in the wet season compared to the dry season. As seen in other tropical blackwater rivers, DOC concentration is consistently around 10 times greater than POC concentration. We estimate the annual TOC flux discharged to the Java Sea to be 0.46 Tg year-1 comprising of 93% (0.43 Tg) DOC and 7% (0.03 Tg) POC. This equates to a fluvial TOC loss flux per unit area over the entire Sebangau catchment of 88g C m-2 yr-1. When extrapolating the Sebangau catchment TOC loss flux (88g C m-2 yr-1) to the peat covered area of Indonesia (206,950 km2), we calculate a TOC loss of 18.2 Tg C yr-1 or ~10% of current estimates of the global annual riverine DOC discharge into the ocean.

  8. Ammonium removal in constructed wetland microcosms as influenced by season and organic carbon load.

    PubMed

    Riley, Kate A; Stein, Otto R; Hook, Paul B

    2005-01-01

    We evaluated ammonium nitrogen removal and nitrogen transformations in three-year-old, batch-operated, subsurface wetland microcosms. Treatments included replicates of Typha latifolia, Carex rostrata, and unplanted controls when influent carbon was excluded, and C. rostrata with an influent containing organic carbon. A series of 10-day batch incubations were conducted over a simulated yearlong cycle of seasons. The presence of plants significantly enhanced ammonium removal during both summer (24 degrees C, active plant growth) and winter (4 degrees C, plant dormancy) conditions, but significant differences between plant species were evident only in summer when C. rostrata outperformed T. latifolia. The effect of organic carbon load was distinctly seasonal, enhancing C. rostrata ammonium removal in winter but having an inhibitory effect in summer. Season did not influence ammonium removal in T. latifolia or unplanted columns. Net production of organic carbon was evident year-round in units without an influent organic carbon source, but was enhanced in summer, especially for C. rostrata, which produced significantly more than T. latifolia and unplanted controls. No differences in production were evident between species in winter. COD values for C. rostrata microcosms with and without influent organic carbon converged within 24 hours in winter and 7 days in summer. Gravel sorption, microbial immobilization and sequential nitrification/denitrification appear to be the major nitrogen removal mechanisms. All evidence suggests differences between season and species are due to differences in seasonal variation of root-zone oxidation. PMID:15921269

  9. Quantification of functional soil organic carbon pools in a chronosequence of land abandonment in southern Spain.

    NASA Astrophysics Data System (ADS)

    Trigalet, Sylvain; Gabarrón-Galeote, Miguel A.; Van Oost, Kristof; van Wesemael, Bas

    2015-04-01

    Land abandonment is the dominant land use change in the Mediterranean, and determines the soil organic carbon (SOC) as the vegetation recovers during secondary succession. The rate of SOC recovery is influenced by environmental factors such as precipitation, soil properties or other local factors. Using aerial photographs taken in 1956, 1977, 1984, 1998, 2001 and 2009, a chronosequence of crop land abandonment was designed and topsoil samples were taken at each stage of recovery in a region North of Málaga. As SOC is a mixture of functional pools, it is important to isolate organic carbon with distinct functional properties to better understand the overall dynamic over decades. Using fractionation scheme introduced by Zimmermann et al. (2007), five fractions were isolated based on particle size, density and resistance: particulate organic matter (POM), dissolved organic carbon (DOC), SOC linked to silt and clay (s & c), SOC attached to sand particles or occluded in aggregates (S+A) and a chemically resistant fraction obtained by NaOCl oxidation (rSOC). Although there were no significant changes in particle-size distribution between the recovery stages (except for the croplands), there was a significant increase of S+A fraction over time (16 to 38%) at the expense of the s & c fraction (84 to 58%), indicating aggregation processes. Carbon concentrations within fractions S+A or rSOC did not change over time. Rather, carbon associated with silt and clay particles (s &c) was significantly affected after a few decades of abandonment. It increased from 5.7 gC.kg-1 in croplands to 10.3 gC.kg-1 in semi-natural plots. The chronosequence showed that carbon can be stored in more stable fractions. Taking into account active carbon (DOC + POM) and intermediate carbon (s & c, S+A) as indicators for carbon dynamics, we showed that the proportion of active carbon increased from 11% to 34% within the chronosequence. On the other hand, the proportion of slow cycling carbon

  10. Pathways of organic carbon oxidation in three continental margin sediments

    NASA Technical Reports Server (NTRS)

    Canfield, D. E.; Jorgensen, B. B.; Fossing, H.; Glud, R.; Gundersen, J.; Ramsing, N. B.; Thamdrup, B.; Hansen, J. W.; Nielsen, L. P.; Hall, P. O.

    1993-01-01

    We have combined several different methodologies to quantify rates of organic carbon mineralization by the various electron acceptors in sediments from the coast of Denmark and Norway. Rates of NH4+ and Sigma CO2 liberation sediment incubations were used with O2 penetration depths to conclude that O2 respiration accounted for only between 3.6-17.4% of the total organic carbon oxidation. Dentrification was limited to a narrow zone just below the depth of O2 penetration, and was not a major carbon oxidation pathway. The processes of Fe reduction, Mn reduction and sulfate reduction dominated organic carbon mineralization, but their relative significance varied depending on the sediment. Where high concentrations of Mn-oxide were found (3-4 wt% Mn), only Mn reduction occurred. With lower Mn oxide concentrations more typical of coastal sediments, Fe reduction and sulfate reduction were most important and of a similar magnitude. Overall, most of the measured O2 flux into the sediment was used to oxidized reduced inorganic species and not organic carbon. We suspect that the importance of O2 respiration in many coastal sediments has been overestimated, whereas metal oxide reduction (both Fe and Mn reduction) has probably been well underestimated.

  11. Erosion of organic carbon in the Arctic as a geological carbon dioxide sink

    NASA Astrophysics Data System (ADS)

    Hilton, Robert G.; Galy, Valier; Gaillardet, Jérôme; Dellinger, Mathieu; Bryant, Charlotte; O'Regan, Matt; Gröcke, Darren R.; Coxall, Helen; Bouchez, Julien; Calmels, Damien

    2015-08-01

    Soils of the northern high latitudes store carbon over millennial timescales (thousands of years) and contain approximately double the carbon stock of the atmosphere. Warming and associated permafrost thaw can expose soil organic carbon and result in mineralization and carbon dioxide (CO2) release. However, some of this soil organic carbon may be eroded and transferred to rivers. If it escapes degradation during river transport and is buried in marine sediments, then it can contribute to a longer-term (more than ten thousand years), geological CO2 sink. Despite this recognition, the erosional flux and fate of particulate organic carbon (POC) in large rivers at high latitudes remains poorly constrained. Here, we quantify the source of POC in the Mackenzie River, the main sediment supplier to the Arctic Ocean, and assess its flux and fate. We combine measurements of radiocarbon, stable carbon isotopes and element ratios to correct for rock-derived POC. Our samples reveal that the eroded biospheric POC has resided in the basin for millennia, with a mean radiocarbon age of 5,800 +/- 800 years, much older than the POC in large tropical rivers. From the measured biospheric POC content and variability in annual sediment yield, we calculate a biospheric POC flux of teragrams of carbon per year from the Mackenzie River, which is three times the CO2 drawdown by silicate weathering in this basin. Offshore, we find evidence for efficient terrestrial organic carbon burial over the Holocene period, suggesting that erosion of organic carbon-rich, high-latitude soils may result in an important geological CO2 sink.

  12. Erosion of organic carbon in the Arctic as a geological carbon dioxide sink.

    PubMed

    Hilton, Robert G; Galy, Valier; Gaillardet, Jérôme; Dellinger, Mathieu; Bryant, Charlotte; O'Regan, Matt; Gröcke, Darren R; Coxall, Helen; Bouchez, Julien; Calmels, Damien

    2015-08-01

    Soils of the northern high latitudes store carbon over millennial timescales (thousands of years) and contain approximately double the carbon stock of the atmosphere. Warming and associated permafrost thaw can expose soil organic carbon and result in mineralization and carbon dioxide (CO2) release. However, some of this soil organic carbon may be eroded and transferred to rivers. If it escapes degradation during river transport and is buried in marine sediments, then it can contribute to a longer-term (more than ten thousand years), geological CO2 sink. Despite this recognition, the erosional flux and fate of particulate organic carbon (POC) in large rivers at high latitudes remains poorly constrained. Here, we quantify the source of POC in the Mackenzie River, the main sediment supplier to the Arctic Ocean, and assess its flux and fate. We combine measurements of radiocarbon, stable carbon isotopes and element ratios to correct for rock-derived POC. Our samples reveal that the eroded biospheric POC has resided in the basin for millennia, with a mean radiocarbon age of 5,800 ± 800 years, much older than the POC in large tropical rivers. From the measured biospheric POC content and variability in annual sediment yield, we calculate a biospheric POC flux of 2.2(+1.3)(-0.9) teragrams of carbon per year from the Mackenzie River, which is three times the CO2 drawdown by silicate weathering in this basin. Offshore, we find evidence for efficient terrestrial organic carbon burial over the Holocene period, suggesting that erosion of organic carbon-rich, high-latitude soils may result in an important geological CO2 sink. PMID:26245581

  13. Activated carbon monoliths for methane storage

    NASA Astrophysics Data System (ADS)

    Chada, Nagaraju; Romanos, Jimmy; Hilton, Ramsey; Suppes, Galen; Burress, Jacob; Pfeifer, Peter

    2012-02-01

    The use of adsorbent storage media for natural gas (methane) vehicles allows for the use of non-cylindrical tanks due to the decreased pressure at which the natural gas is stored. The use of carbon powder as a storage material allows for a high mass of methane stored for mass of sample, but at the cost of the tank volume. Densified carbon monoliths, however, allow for the mass of methane for volume of tank to be optimized. In this work, different activated carbon monoliths have been produced using a polymeric binder, with various synthesis parameters. The methane storage was studied using a home-built, dosing-type instrument. A monolith with optimal parameters has been fabricated. The gravimetric excess adsorption for the optimized monolith was found to be 161 g methane for kg carbon.

  14. Soil Organic Carbon dynamics in agricultural soils of Veneto Region

    NASA Astrophysics Data System (ADS)

    Bampa, F. B.; Morari, F. M.; Hiederer, R. H.; Toth, G. T.; Giandon, P. G.; Vinci, I. V.; Montanarella, L. M.; Nocita, M.

    2012-04-01

    One of the eight soil threats expressed in the European Commission's Thematic Strategy for Soil Protection (COM (2006)231 final) it's the decline in Soil Organic Matter (SOM). His preservation is recognized as with the objective to ensure that the soils of Europe remain healthy and capable of supporting human activities and ecosystems. One of the key goals of the strategy is to maintain and improve Soil Organic Carbon (SOC) levels. As climate change is identified as a common element in many of the soil threats, the European Commission (EC) intends to assess the actual contribution of the soil protection to climate change mitigation and the effects of climate change on the possible depletion of SOM. A substantial proportion of European land is occupied by agriculture, and consequently plays a crucial role in maintaining natural resources. Organic carbon preservation and sequestration in the EU's agricultural soils could have some potential to mitigate the effects of climate change, particularly linked to preventing certain land use changes and maintaining SOC stocks. The objective of this study is to assess the SOC dynamics in agricultural soils (cropland and grassland) at regional scale, focusing on changes due to land use. A sub-objective would be the evaluation of the most used land management practices and their effect on SOC content. This assessment aims to determine the geographical distribution of the potential GHG mitigation options, focusing on hot spots in the EU, where mitigation actions would be particularly efficient and is linked with the on-going work in the JRC SOIL Action. The pilot area is Veneto Region. The data available are coming from different sources, timing and involve different variables as: soil texture, climate, soil disturbance, managements and nutrients. The first source of data is the LUCAS project (Land Use/Land Cover Area Frame statistical Survey). Started in 2001, the LUCAS project aims to monitor changes in land cover/use and

  15. Soil Microbial Activity Provides Insight to Carbon Cycling in Shrub Ecotones of Sub-Arctic Sweden

    NASA Astrophysics Data System (ADS)

    Marek, E.; Kashi, N. N.; Chen, J.; Hobbie, E. A.; Schwan, M. R.; Varner, R. K.

    2015-12-01

    Shrubs are expanding in Arctic and sub-Arctic regions due to rising atmospheric temperatures. Microbial activity increases as growing temperatures cause permafrost warming and subsequent thaw, leading to a greater resource of soil nutrients enabling shrub growth. Increased carbon inputs from shrubs is predicted to result in faster carbon turnover by microbial decomposition. Further understanding of microbial activity underneath shrubs could uncover how microbes and soil processes interact to promote shrub expansion and carbon cycling. To address how higher soil carbon input from shrubs influences decomposition, soil samples were taken across a heath, shrub, and forest ecotone gradient at two sites near Abikso, Sweden. Samples were analyzed for soluble carbon and nitrogen, microbial abundance, and microbial activity of chitinase, glucosidase, and phosphatase to reflect organic matter decomposition and availability of nitrogen, carbon, and phosphate respectively. Chitinase activity positively correlated with shrub cover, suggesting microbial demands for nitrogen increase with higher shrub cover. Glucosidase activity negatively correlated with shrub cover and soluble carbon, suggesting decreased microbial demand for carbon as shrub cover and carbon stores increase. Lower glucosidase activity in areas with high carbon input from shrubs implies that microbes are decomposing carbon less readily than carbon is being put into the soil. Increasing soil carbon stores in shrub covered areas can lead to shrubs becoming a net carbon sink and a negative feedback to changing climate.

  16. Removal of benzocaine from water by filtration with activated carbon

    USGS Publications Warehouse

    Howe, G.E.; Bills, T.D.; Marking, L.L.

    1990-01-01

    Benzocaine is a promising candidate for registration with the U.S. Food and Drug Administration for use as an anesthetic in fish culture, management, and research. A method for the removal of benzocaine from hatchery effluents could speed registration of this drug by eliminating requirements for data on its residues, tolerances, detoxification, and environmental hazards. Carbon filtration effectively removes many organic compounds from water. This study tested the effectiveness of three types of activated carbon for removing benzocaine from water by column filtration under controlled laboratory conditions. An adsorptive capacity was calculated for each type of activated carbon. Filtrasorb 400 (12 x 40 mesh; U.S. standard sieve series) showed the greatest capacity for benzocaine adsorption (76.12 mg benzocaine/g carbon); Filtrasorb 300 (8 x 30 mesh) ranked next (31.93 mg/g); and Filtrasorb 816 (8 x 16 mesh) absorbed the least (1.0 mg/g). Increased adsorptive capacity was associated with smaller carbon particle size; however, smaller particle size also impeded column flow. Carbon filtration is a practical means for removing benzocaine from treated water.

  17. Distinguishing Terrestrial Organic Carbon in Marginal Sediments of East China Sea and Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Kandasamy, Selvaraj; Lin, Baozhi; Wang, Huawei; Liu, Qianqian; Liu, Zhifei; Lou, Jiann-Yuh; Chen, Chen-Tung Arthur; Mayer, Lawrence M.

    2016-04-01

    Knowledge about the sources, transport pathways and behavior of terrestrial organic carbon in continental margins adjoining to large rivers has improved in recent decades, but uncertainties and complications still exist with human-influenced coastal regions in densely populated wet tropics and subtropics. In these regions, the monsoon and other episodic weather events exert strong climatic control on mineral and particulate organic matter delivery to the marginal seas. Here we investigate elemental (TOC, TN and bromine-Br) and stable carbon isotopic (δ13C) compositions of organic matter (OM) in surface sediments and short cores collected from active (SW Taiwan) and passive margin (East China Sea) settings to understand the sources of OM that buried in these settings. We used sedimentary bromine to total organic carbon (Br/TOC) ratios to apportion terrigenous from marine organic matter, and find that Br/TOC may serve as an additional, reliable proxy for sedimentary provenance in both settings. Variations in Br/TOC are consistent with other provenance indicators in responding to short-lived terrigenous inputs. Because diagenetic alteration of Br is insignificant on shorter time scales, applying Br/TOC ratios as a proxy to identify organic matter source along with carbon isotope mixing models may provide additional constraints on the quantity and transformation of terrigenous organics in continental margins. We apply this combination of approaches to land-derived organic matter in different depositional environments of East Asian marginal seas.

  18. Cost effective tools for soil organic carbon monitoring

    NASA Astrophysics Data System (ADS)

    Shepherd, Keith; Aynekulu, Ermias

    2013-04-01

    There is increasing demand for data on soil properties at fine spatial resolution to support management and planning decisions. Measurement of soil organic carbon has attracted much interest because (i) soil organic carbon is widely cited as a useful indicator of soil condition and (ii) of the importance of soil carbon in the global carbon cycle and climate mitigation strategies. However in considering soil measurement designs there has been insufficient attention given to careful analysis of the specific decisions that the measurements are meant to support and on what measurements have high information value for decision-making. As a result, much measurement effort may be wasted or focused on the wrong variables. A cost-effective measurement is one that reduces risk in decisions and does not cost more than the societal returns to additional evidence. A key uncertainty in measuring soil carbon as a soil condition indicator is what constitutes a good or bad level of carbon on a given soil. A measure of soil organic carbon concentration may have limited value for informing management decisions without the additional information required to interpret it, and so expending further efforts on improving measurements to increase precision may then have no value to improving the decision. Measuring soil carbon stock changes for carbon trading purposes requires high levels of measurement precision but there is still large uncertainty on whether the costs of measurement exceed the benefits. Since the largest cost component in soil monitoring is often travel to the field and physically sampling soils, it is generally cost-effective to meet multiple objectives by analysing a number of properties on a soil sample. Diffuse reflectance infrared spectroscopy is playing a key role in allowing multiple soil properties to be determined rapidly and at low cost. The method provides estimation of multiple soil properties (e.g. soil carbon, texture and mineralogy) in one measurement

  19. Light absorption by organic carbon from wood combustion

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Bond, T. C.

    2009-09-01

    Carbonaceous aerosols affect the radiative balance of the Earth by absorbing and scattering light. While BC is highly absorbing, some organic compounds also have significant absorption, which is greater at near-ultraviolet and blue wavelengths. To the extent that OC absorbs visible light, it may be a non-negligible contributor to direct aerosol radiative forcing. In this work, we examine absorption by primary OC emitted from solid fuel pyrolysis. We provide absorption spectra of this material, which can be related to the imaginary refractive index. This material has polar character but is not fully water-soluble: more than 92% was extractable by methanol or acetone, compared with 73% for water and 52% for hexane. Water-soluble organic carbon contributed to light absorption at both ultraviolet and visible wavelengths. However, a larger portion came from organic carbon that is extractable only by methanol. The spectra of water-soluble organic carbon are similar to others in the literature. We compared spectra for material generated with different wood type, wood size and pyrolysis temperature. Higher wood temperature is the main factor creating organic aerosol with higher absorption, causing about a factor of four increase in mass-normalized absorption at visible wavelengths. A simple model suggests that, despite the absorption, both high-temperature and low-temperature carbon have negative climate forcing over a surface with average albedo.

  20. The influence of organic carbon flux on benthic foraminiferal proxies

    NASA Astrophysics Data System (ADS)

    Corliss, B. H.; Sun, X.; Brown, C. W.; Showers, W. J.

    2005-12-01

    During the last 30 years, deep-sea benthic foraminifera have been widely used in reconstructing environmental conditions in the deep sea. Initial suggestions of faunal-water mass associations were never substantiated and, instead, organic carbon flux was identified as a primary influence on species and assemblage patterns. Organic carbon flux also impacts the chemistry of deep water masses and is reflected in the stable isotopic and trace element composition of a number of deep-sea taxa. The timing of delivery of organic carbon can also have an affect on foraminiferal chemistry. Carbon-13 data of Holocene Epistominella exigua from the North Atlantic show a 0.9 per mil change over 60 degrees of latitude that can be correlated to seasonality of productivity, based on a comparison of SeaWIFS satellite imagery. Seasonality and mean annual primary productivity do not affect the carbon-13 of Planulina wuellerstorfi in the North Atlantic, although P. wuellerstorfi exhibits significant variability. Our results suggest that the carbon-13 of E. exigua in conjunction with P. wuellerstorfi can be used to reconstruct seasonality of primary productivity. These findings raise the possibility that other geochemical proxies influenced by particle flux from the surface may be affected by periodic flux events that create phytodetritus layers and change the chemistry of the microhabitats occupied by some benthic foraminiferal species. Existing studies suggest that organic carbon flux and seasonality of flux influence both faunal and geochemical signals from benthic foraminiferal. These relationships can be used to reconstruct primary productivity and seasonality, in addition to deep-water circulation, and illustrate the importance of incorporating ecological information in the interpretation of geochemical data from deep sea taxa.

  1. Semicontinuous automated measurement of organic carbon in atmospheric aerosol samples.

    PubMed

    Lu, Chao; Rashinkar, Shilpa M; Dasgupta, Purnendu K

    2010-02-15

    A fully automated measurement system for ambient aerosol organic carbon, capable of unattended operation over extended periods, is described. Particles are collected in a cyclone with water as the collection medium. The collected sample is periodically aspirated by a syringe pump into a holding loop and then delivered to a wet oxidation reactor (WOR). Acid is added, and the WOR is purged to measure dissolved CO(2) or inorganic carbonates (IC) as evolved CO(2). The IC background can often be small and sufficiently constant to be corrected for, without separate measurement, by a blank subtraction. The organic material is now oxidized stepwise or in one step to CO(2). The one-step oxidation involves UV-persulfate treatment in the presence of ozone. This treatment converts organic carbon (OC) to CO(2), but elemental carbon is not oxidized. The CO(2) is continuously purged from solution and collected by two sequential miniature diffusion scrubbers (DSs), a short DS preceding a longer one. Each DS consists of a LiOH-filled porous hydrophobic membrane tube with terminal stainless steel tubes that function as conductance-sensing electrodes. As CO(2) is collected by the LiOH-filled DSs, hydroxide is converted into carbonate and the resulting decrease in conductivity is monitored. The simultaneous use of the dual short and long DS units bearing different concentrations of LiOH permits both good sensitivity and a large dynamic range. The limit of detection (LOD, S/N = 3) is approximately 140 ng of C. With a typical sampling period of 30 min at a sampling rate of 30 L/min, this corresponds to an LOD of 160 ng/m(3). The approach also provides information on the ease of oxidation of the carbonaceous aerosol and hence the nature of the carbon contained therein. Ambient aerosol organic carbon data are presented. PMID:20092351

  2. Parameterization of the influence of organic surfactants on aerosol activation

    NASA Astrophysics Data System (ADS)

    Abdul-Razzak, Hayder; Ghan, Steven J.

    2004-02-01

    Surface-active organic compounds, or surfactants, can affect aerosol activation by two mechanisms: lowering surface tension and altering the bulk hygroscopicity of the particles. A numerical model has been developed to predict the activation of aerosol particles consisting of an internally uniform chemical mixture of organic surfactants and inorganic salts in a parcel of air rising adiabatically at constant speed. Equations reflecting water balance of the air parcel were used together with a modified form of Köhler theory to model droplet nucleation while considering surface effects. We also extend a parametric representation of aerosol activation to the case of a mixture of inorganic salts and organic surfactants by modifying the Raoult term in Köhler theory (assuming additive behavior) and using a simplified relationship between surface tension and surfactant molar concentration to account for surface effects at the critical radius for activation. The close agreement (to within 10% for most and 20% for almost all conditions) between numerical and parametric results validates our modifications. Moreover, the form of the relationship is identical to an empirical relationship between surface tension and organic carbon concentration. Thus the modified form of the parameterization provides a framework that can account for the influence of observed organics on the activation of other salts. The modified form of the parameterization is tested successfully with the Po Valley model both for single aerosol size distribution and three-mode size distributions for marine, rural, and urban aerosols. Further measurements are required to extend the parameterization to other organic surfactants.

  3. Catalytic Coupling of Carbon Dioxide with Terpene Scaffolds: Access to Challenging Bio-Based Organic Carbonates.

    PubMed

    Fiorani, Giulia; Stuck, Moritz; Martín, Carmen; Belmonte, Marta Martínez; Martin, Eddy; Escudero-Adán, Eduardo C; Kleij, Arjan W

    2016-06-01

    The challenging coupling of highly substituted terpene oxides and carbon dioxide into bio-based cyclic organic carbonates catalyzed by Al(aminotriphenolate) complexes is reported. Both acyclic as well as cyclic terpene oxides were used as coupling partners, showing distinct reactivity/selectivity behavior. Whereas cyclic terpene oxides showed excellent chemoselectivity towards the organic carbonate product, acyclic substrates exhibited poorer selectivities owing to concomitant epoxide rearrangement reactions and the formation of undesired oligo/polyether side products. Considering the challenging nature of these coupling reactions, the isolated yields of the targeted bio-carbonates are reasonable and in most cases in the range 50-60 %. The first crystal structures of tri-substituted terpene based cyclic carbonates are reported and their stereoconnectivity suggests that their formation proceeds through a double inversion pathway. PMID:27159151

  4. Effect of some organic solvent-water mixtures composition on precipitated calcium carbonate in carbonation process

    NASA Astrophysics Data System (ADS)

    Konopacka-Łyskawa, Donata; Kościelska, Barbara; Karczewski, Jakub

    2015-05-01

    Precipitated calcium carbonate particles were obtained during carbonation of calcium hydroxide slurry with carbon dioxide. Aqueous solutions of isopropyl alcohol, n-butanol and glycerol were used as solvents. Concentration of organic additives in the reactive mixture was from 0% to 20% (vol). Precipitation process were performed in a stirred tank reactor equipped with gas distributor. Multimodal courses of particles size distribution were determined for produced CaCO3 particles. Calcium carbonate as calcite was precipitated in all experiments. The mean Sauter diameter of CaCO3 particles decreased when the concentration of all used organic additives increased. The amount of small particle fraction in the product increased with the increasing concentration of organic solvents. Similar physical properties of used liquid phase resulted in the similar characteristics of obtained particles.

  5. Facile Carbonization of Microporous Organic Polymers into Hierarchically Porous Carbons Targeted for Effective CO2 Uptake at Low Pressures.

    PubMed

    Gu, Shuai; He, Jianqiao; Zhu, Yunlong; Wang, Zhiqiang; Chen, Dongyang; Yu, Guipeng; Pan, Chunyue; Guan, Jianguo; Tao, Kai

    2016-07-20

    The advent of microporous organic polymers (MOPs) has delivered great potential in gas storage and separation (CCS). However, the presence of only micropores in these polymers often imposes diffusion limitations, which has resulted in the low utilization of MOPs in CCS. Herein, facile chemical activation of the single microporous organic polymers (MOPs) resulted in a series of hierarchically porous carbons with hierarchically meso-microporous structures and high CO2 uptake capacities at low pressures. The MOPs precursors (termed as MOP-7-10) with a simple narrow micropore structure obtained in this work possess moderate apparent BET surface areas ranging from 479 to 819 m(2) g(-1). By comparing different activating agents for the carbonization of these MOPs matrials, we found the optimized carbon matrials MOPs-C activated by KOH show unique hierarchically porous structures with a significant expansion of dominant pore size from micropores to mesopores, whereas their microporosity is also significantly improved, which was evidenced by a significant increase in the micropore volume (from 0.27 to 0.68 cm(3) g(-1)). This maybe related to the collapse and the structural rearrangement of the polymer farmeworks resulted from the activation of the activating agent KOH at high temperature. The as-made hierarchically porous carbons MOPs-C show an obvious increase in the BET surface area (from 819 to 1824 m(2) g(-1)). And the unique hierarchically porous structures of MOPs-C significantly contributed to the enhancement of the CO2 capture capacities, which are up to 214 mg g(-1) (at 273 K and 1 bar) and 52 mg g(-1) (at 273 K and 0.15 bar), superior to those of the most known MOPs and porous carbons. The high physicochemical stabilities and appropriate isosteric adsorption heats as well as high CO2/N2 ideal selectivities endow these hierarchically porous carbon materials great potential in gas sorption and separation. PMID:27332739

  6. Spatial distribution of soil organic carbon stocks in France

    NASA Astrophysics Data System (ADS)

    Martin, M. P.; Wattenbach, M.; Smith, P.; Meersmans, J.; Jolivet, C.; Boulonne, L.; Arrouays, D.

    2010-11-01

    Soil organic carbon plays a major role in the global carbon budget, and can act as a source or a sink of atmospheric carbon, whereby it can influence the course of climate change. Changes in soil organic soil stocks (SOCS) are now taken into account in international negotiations regarding climate change. Consequently, developing sampling schemes and models for estimating the spatial distribution of SOCS is a priority. The French soil monitoring network has been established on a 16 km × 16 km grid and the first sampling campaign has recently been completed, providing circa 2200 measurements of stocks of soil organic carbon, obtained through an in situ composite sampling, uniformly distributed over the French territory. We calibrated a boosted regression tree model on the observed stocks, modelling SOCS as a function of other variables such as climatic parameters, vegetation net primary productivity, soil properties and land use. The calibrated model was evaluated through cross-validation and eventually used for estimating SOCS for the whole of metropolitan France. Two other models were calibrated on forest and agricultural soils separately, in order to assess more precisely the influence of pedo-climatic variables on soil organic carbon for such soils. The boosted regression tree model showed good predictive ability, and enabled quantification of relationships between SOCS and pedo-climatic variables (plus their interactions) over the French territory. These relationship strongly depended on the land use, and more specifically differed between forest soils and cultivated soil. The total estimate of SOCS in France was 3.260 ± 0.872 PgC for the first 30 cm. It was compared to another estimate, based on the previously published European soil organic carbon and bulk density maps, of 5.303 PgC. We demonstrate that the present estimate might better represent the actual SOCS distributions of France, and consequently that the previously published approach at the European

  7. Preparation of activated carbons with mesopores by use of organometallics

    SciTech Connect

    Yamada, Yoshio; Yoshizawa, Noriko; Furuta, Takeshi

    1996-12-31

    Activated carbons are commercially produced by steam or CO{sub 2} activation of coal, coconut shell and so on. In general the carbons obtained give pores with a broad range of distribution. The objective of this study was to prepare activated carbons from coal by use of various organometallic compounds. The carbons were evaluated for pore size by nitrogen adsorption experiments.

  8. Hydrogen storage on activated carbon. Final report

    SciTech Connect

    Schwarz, J.A.

    1994-11-01

    The project studied factors that influence the ability of carbon to store hydrogen and developed techniques to enhance that ability in naturally occurring and factory-produced commercial carbon materials. During testing of enhanced materials, levels of hydrogen storage were achieved that compare well with conventional forms of energy storage, including lead-acid batteries, gasoline, and diesel fuel. Using the best materials, an electric car with a modern fuel cell to convert the hydrogen directly to electricity would have a range of over 1,000 miles. This assumes that the total allowable weight of the fuel cell and carbon/hydrogen storage system is no greater than the present weight of batteries in an existing electric vehicle. By comparison, gasoline cars generally are limited to about a 450-mile range, and battery-electric cars to 40 to 60 miles. The project also developed a new class of carbon materials, based on polymers and other organic compounds, in which the best hydrogen-storing factors discovered earlier were {open_quotes}molecularly engineered{close_quotes} into the new materials. It is believed that these new molecularly engineered materials are likely to exceed the performance of the naturally occurring and manufactured carbons seen earlier with respect to hydrogen storage.

  9. Ultrasonic Spraying of Carbon Nanotubes using Organic Solvents

    NASA Astrophysics Data System (ADS)

    Willey, Anthony; Davis, Robert; Vanfleet, Richard

    2012-10-01

    Because of their unique electrical and mechanical properties, thin films of carbon nanotubes have several potential applications, especially in the fields of organic electronics and photovoltaics. We present a method for spraying thin films of nanotubes that have been suspended in organic solvents N-methyl Pyrollidone (NMP) and N-Cyclohexyl-2-pyrrolidone (CHP). The sprayed nanotubes are randomly oriented, and films are transparent, conductive, and mechanically stable.

  10. Standardizing Organic Carbon Measurements for Modern and Geologic Timescales

    NASA Astrophysics Data System (ADS)

    Wang, R. Z.; Yager, J. A.; Rollins, N.; Berelson, W.; West, A. J.; Li, G.

    2015-12-01

    Accurate reconstruction of carbon isotope records (as well as accurate characterization of the modern carbon cycle, e.g., in soils) relies on reliably separating organic carbon (Corg) from carbonate-derived carbon (Ccarb). These fractions are characterized by very different isotope composition, so small carbonate contamination can strongly bias Corg results, and vice versa. Several criteria must be met for accurate %C and d13C analysis. In the case of analyzing Corg, these include: (1) Ccarb must be removed through a process called "decarbonation." (2) Ccarb can be removed by acid dissolution, but if the acid is too strong then the Corg itself may solubilize, causing inaccurate results. (3) The preparation process for decarbonation can also unintentionally add carbon to samples and create a methodological blank that also will bias results. This study tested decarbonation methods with the above criteria in mind. The focus was on (i) heated treatment with weak liquid acid, e.g., 1M HCl ("liquid phase decarbonation") and (ii) heated treatment with vapor from concentrated acid ("vapor phase decarbonation"). Our results confirm that heated treatment is critical to producing reliable records; recalcitrant carbonate phases are not removed during room temperature decarbonation and can bias carbon isotope values. Vapor phase decarbonation may prevent loss in solution that is known to occur using liquid phase methods. However, our results show that blanks must be very carefully monitored and can be a concern during vapor phase treatment. Moreover, we still observe some loss of organics during vapor phase treatment, as evidenced by changes in Corg and d13C with length of reaction time. The length of vapor phase treatment must be carefully considered depending on the type of sample being tested. Overall, our work emphasizes the importance of carefully considering sample-specific decarbonation methodology in order to produce reliable values for %Corg and d13C.

  11. Organic carbon burial efficiency in a large tropical hydroelectric reservoir

    NASA Astrophysics Data System (ADS)

    Mendonça, Raquel; Sobek, Sebastian; Kosten, Sarian; Cole, Jonathan; Cardoso, Simone; Roland, Fábio

    2014-05-01

    Because hydroelectric reservoirs receive relatively high inputs of sediments when compared to lakes and oceans, these systems are important sites for organic carbon (OC) accumulation. Nevertheless, the actual magnitude of carbon accumulating in reservoirs is poorly known due to a lack of whole-system studies of carbon burial. Hydroelectric reservoirs are also particularly heterogeneous systems in terms of organic carbon sources and sedimentation rates. Such heterogeneity leads to strong variations on carbon fluxes, even though the effect on OC burial has not yet been discussed. The aim of this paper was to determine the OC burial rate and efficiency in a large tropical reservoir and evaluate the importance of spatial heterogeneity affecting OC burial. Burial rates were determined through a novel approach which combines sediment sample analyses and a seismic survey. Our results confirm the major effect of sedimentation heterogeneity on OC burial efficiency which varied from 9 to 89% in the reservoir. In addition to the river-dam gradient of sedimentation, our data reinforce the importance of basin morphometry in determining the patterns of sediment deposition and carbon accumulation. No carbon accumulation occurred along the margins of the reservoir and irregular bottom morphology leaded to irregular carbon deposition. An integrative analysis, including the reservoir's heterogeneity, indicated that the whole system accumulates 42.2 g C m-2 yr-1 and that roughly 67% of the total OC load to the sediments is actually buried. The data also suggest that the sediment of the reservoir is mainly composed of terrestrial OC and that the heterogeneity in OC sources plays a minor role determining OC burial efficiency, which was strongly determined by sediment accumulation rate. Finally, our results in combination with literature data suggest that the high sedimentation rates cause hydroelectric reservoirs to accumulate carbon more efficiently than lakes, regardless of

  12. Are we overestimating organic carbon concentrations in soils containing inorganic carbon?

    NASA Astrophysics Data System (ADS)

    Cunliffe, Andrew; Brazier, Richard; Vernon, Ian

    2014-05-01

    The concentration of carbon in soils is often measured via chromatographic analysis of elemental gases following dry combustion of a soil sample. This quantifies total carbon (TC), and, in soils which can be assumed to contain no inorganic carbon (IC), TC can be interpreted as organic carbon (OC). Soils containing IC are commonly subjected to an acid digestion to remove IC, prior to analysis for OC concentration; with IC being assigned as the difference between TC and OC. However, the removal of IC reduces the sample mass. Therefore, analysing acid-washed samples reveals the carbon concentration of the non-inorganic carbon sample mass, rather than the actual sample mass, as is generally assumed. This results in the overestimation of OC concentrations and consequent underestimation of IC concentrations, although TC concentrations are correct. The magnitude of the error is proportional to both IC concentration, and the ratio OC/IC, and consequently is greater in carbonate-rich samples. We present a revised protocol for accurately calculating OC and IC concentrations, using the carbon concentrations of the total sample and the acid-washed sample. The revised protocol is easily applicable to existing data, and corrects a known bias in apportioning carbon between organic and inorganic pools. Propagating the error through an example dataset from a semiarid environment, we find it can make a substantial (>10%) difference to estimated total OC pools. We recommend that this new protocol is used whenever elemental analysers are used to quantify OC concentrations in acid-washed sediments.

  13. Organic carbon accumulation and preservation in surface sediments on the Peru margin

    USGS Publications Warehouse

    Arthur, M.A.; Dean, W.E.; Laarkamp, K.

    1998-01-01

    Concentrations and characteristics of organic matter in surface sediments deposited under an intense oxygen-minimum zone on the Peru margin were studied in samples from deck-deployed box cores and push cores acquired by submersible on two transects spanning depths of 75 to 1000 m at 12??and 13.5??S. The source of organic matter to the seafloor in these areas is almost entirely marine material as confirmed by the narrow range of ??13C of organic carbon obtained in the present study (-20.3 to -21.6???; PDB) and the lack of any relationship between pyrolysis hydrogen index and carbon isotope composition. Organic carbon contents are highest (up to 16%) on the slope at depths between 75 and 350 m in sediments deposited under intermediate water masses with low dissolved oxygen concentrations (< 5 ??mol/kg). Even at these low concentrations of dissolved oxygen, however, the surface sediments that were recovered from these depths are dominantly unlaminated. Strong currents (up to 30 cm/s) associated with the poleward-flowing Peru Undercurrent were measured at depths between 160 and 300 m on both transects. The seafloor in this range of water depths is characterized by bedforms stabilized by bacterial mats, extensive authigenic mineral crusts, and (or) thick organic flocs. Constant advection of dissolved oxygen, although in low concentrations, active resuspension of surficial organic matter, activity of organisms, and transport of fine-grained sediment to and from more oxygenated zones all contribute to greater degradation and poorer initial preservation of organic matter than might be expected under oxygen-deficient conditions. Dissolved-oxygen concentrations ultimately may be the dominant affect on organic matter characteristics, but reworking of fine-grained sediment and organic matter by strong bottom currents and redeposition on the seafloor in areas of lower energy also exert important controls on organic carbon concentration and degree of oxidation in this region.

  14. Selective Sorption of Dissolved Organic Carbon Compounds by Temperate Soils

    SciTech Connect

    Jagadamma, Sindhu; Mayes, Melanie; Phillips, Jana Randolph

    2012-01-01

    Physico-chemical sorption of dissolved organic carbon (DOC) on soil minerals is one of the major processes of organic carbon (OC) stabilization in soils, especially in deeper layers. The attachment of C on soil solids is related to the reactivity of the soil minerals and the chemistry of the sorbate functional groups, but the sorption studies conducted without controlling microbial activity may overestimate the sorption potential of soil. This study was conducted to examine the sorptive characteristics of a diverse functional groups of simple OC compounds (D-glucose, L-alanine, oxalic acid, salicylic acid, and sinapyl alcohol) on temperate climate soil orders (Mollisols, Ultisols and Alfisols) with and without biological degradative processes. Equilibrium batch experiments were conducted using 0-100 mg C L-1 at a solid-solution ratio of 1:60 for 48 hrs and the sorption parameters were calculated by Langmuir model fitting. The amount of added compounds that remained in the solution phase was detected by high performance liquid chromatography (HPLC) and total organic C (TOC) analysis. Soil sterilization was performed by -irradiation technique and experiments were repeated to determine the contribution of microbial degradation to apparent sorption. Overall, Ultisols did not show a marked preference for apparent sorption of any of the model compounds, as indicated by a narrower range of maximum sorption capacity (Smax) of 173-527 mg kg soil-1 across compounds. Mollisols exhibited a strong preference for apparent sorption of oxalic acid (Smax of 5290 mg kg soil-1) and sinapyl alcohol (Smax of 2031 mg kg soil-1) over the other compounds. The propensity for sorption of oxalic acid is mainly attributed to the precipitation of insoluble Ca-oxalate due to the calcareous nature of most Mollisol subsoils and its preference for sinapyl alcohol could be linked to the polymerization of this lignin monomer on 2:2 mineral dominated soils. The reactivity of Alfisols to DOC was in

  15. MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON

    EPA Science Inventory

    The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

  16. Making Activated Carbon for Storing Gas

    NASA Technical Reports Server (NTRS)

    Wojtowicz, Marek A.; Serio, Michael A.; Suuberg, Eric M.

    2005-01-01

    Solid disks of microporous activated carbon, produced by a method that enables optimization of pore structure, have been investigated as means of storing gas (especially hydrogen for use as a fuel) at relatively low pressure through adsorption on pore surfaces. For hydrogen and other gases of practical interest, a narrow distribution of pore sizes <2 nm is preferable. The present method is a variant of a previously patented method of cyclic chemisorption and desorption in which a piece of carbon is alternately (1) heated to the lower of two elevated temperatures in air or other oxidizing gas, causing the formation of stable carbon/oxygen surface complexes; then (2) heated to the higher of the two elevated temperatures in flowing helium or other inert gas, causing the desorption of the surface complexes in the form of carbon monoxide. In the present method, pore structure is optimized partly by heating to a temperature of 1,100 C during carbonization. Another aspect of the method exploits the finding that for each gas-storage pressure, gas-storage capacity can be maximized by burning off a specific proportion (typically between 10 and 20 weight percent) of the carbon during the cyclic chemisorption/desorption process.

  17. Organic matter diagenesis in shallow water carbonate sediments

    NASA Astrophysics Data System (ADS)

    Ingalls, Anitra E.; Aller, Robert C.; Lee, Cindy; Wakeham, Stuart G.

    2004-11-01

    Muddy carbonate deposits near the Dry Tortugas, Florida, are characterized by high organic carbon remineralization rates. However, approximately half of the total sedimentary organic matter potentially supporting remineralization is occluded in CaCO 3 minerals (intracrystalline). While a portion of nonintracrystalline organic matter appears to cycle rapidly, intracrystalline organic matter has an approximately constant concentration with depth, suggesting that as long as its protective mineral matrix is intact, it is not readily remineralized. Organic matter in excess of intracrystalline organic matter that is preserved may have a variety of mineral associations (e.g., intercrystalline, adsorbed or detrital). In surface sediment, aspartic acid contributed ˜22 mole % and ˜50 mole % to nonintracrystalline and intracrystalline pools, respectively. In deeper sediment (1.6-1.7m), the composition of hydrolyzable amino acids in both pools was similar (aspartic acid ˜40 mole %). Like amino acids, intracrystalline and nonintracrystalline fatty acids have different compositions in surface sediments, but are indistinguishable at depth. These data suggest that preserved organic matter in the nonintracrystalline pool is stabilized by its interactions with CaCO 3. Neutral lipids are present in very low abundances in the intracrystalline pool and are extensively degraded in both the intracrystalline and nonintracrystalline pools, suggesting that mineral interactions do not protect these compounds from degradation. The presence of chlorophyll- a, but absence of phytol, in the intracrystalline lipid pool demonstrates that chloropigments are present only in the nonintracrystalline pool. Sedimentary chloropigments decrease with depth at similar rates in Dry Tortugas sediments as found in alumino-silicate sediments from the Long Island Sound, suggesting that chloropigment degradation is largely unaffected by mineral interactions. Overall, however, inclusion and protection of

  18. Organic carbon production, mineralization and preservation on the Peruvian margin

    NASA Astrophysics Data System (ADS)

    Dale, A. W.; Sommer, S.; Lomnitz, U.; Montes, I.; Treude, T.; Gier, J.; Hensen, C.; Dengler, M.; Stolpovsky, K.; Bryant, L. D.; Wallmann, K.

    2014-09-01

    Carbon cycling in Peruvian margin sediments (11° S and 12° S) was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC) content was lowest on the inner shelf and at the deep oxygenated stations (< 5%) and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15-20%). The organic carbon burial efficiency (CBE) was unexpectedly low on the inner shelf (< 20%) when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%). Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09). Yet, mean POC burial rates were 2-5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments.

  19. Converting poultry litter to activated carbon: optimal carbonization conditions and product sorption for benzene.

    PubMed

    Guo, Mingxin; Song, Weiping

    2011-12-01

    To promote utilization of poultry litter as a source material for manufacturing low-cost activated carbon (AC) that can be used in wastewater treatment, this study investigated optimal production conditions and water-borne organic sorption potential of poultry litter-based AC. Pelletized broiler litter was carbonized at different temperatures for varied time periods and activated with steam at a range of flow rate and time. The AC products were examined for quality characteristics using standard methods and for organic sorption potentials using batch benzene sorption techniques. The study shows that the yield and quality of litter AC varied with production conditions. The optimal production conditions for poultry litter-based AC were carbonization at 700 degrees C for 45 min followed by activation with 2.5 ml min(-1) steam for another 45 min. The resulting AC possessed an iodine number of 454 mg g(-1) and a specific surface area of 403 m2 g(-1). It sorbed benzene in water following sigmoidal kinetic and isothermal patterns. The sorption capacity for benzene was 23.70 mg g(-1), lower than that of top-class commercial AC. The results, together with other reported research findings, suggest that poultry litter is a reasonable feedstock for low-cost AC applicable to pre-treat wastewater contaminated by organic pollutants and heavy metals. PMID:22439566

  20. Organic carbon cycling in landfills: Model for a continuum approach

    SciTech Connect

    Bogner, J.; Lagerkvist, A.

    1997-09-01

    Organic carbon cycling in landfills can be addressed through a continuum model where the end-points are conventional anaerobic digestion of organic waste (short-term analogue) and geologic burial of organic material (long-term analogue). Major variables influencing status include moisture state, temperature, organic carbon loading, nutrient status, and isolation from the surrounding environment. Bioreactor landfills which are engineered for rapid decomposition approach (but cannot fully attain) the anaerobic digester end-point and incur higher unit costs because of their high degree of environmental isolation and control. At the other extreme, uncontrolled land disposal of organic waste materials is similar to geologic burial where organic carbon may be aerobically recycled to atmospheric CO{sub 2}, anaerobically converted to CH{sub 4} and CO{sub 2} during early diagenesis, or maintained as intermediate or recalcitrant forms into geologic time (> 1,000 years) for transformations via kerogen pathways. A family of improved landfill models are needed at several scales (molecular to landscape) which realistically address landfill processes and can be validated with field data.

  1. Carbonaceous aerosols influencing atmospheric radiation: Black and organic carbon

    SciTech Connect

    Penner, J.E.

    1994-09-01

    Carbonaceous particles in the atmosphere may both scatter and absorb solar radiation. The fraction associated with the absorbing component is generally referred to as black carbon (BC) and is mainly produced from incomplete combustion processes. The fraction associated with condensed organic compounds is generally referred to as organic carbon (OC) or organic matter and is mainly scattering. Absorption of solar radiation by carbonaceous aerosols may heat the atmosphere, thereby altering the vertical temperature profile, while scattering of solar radiation may lead to a net cooling of the atmosphere/ocean system. Carbonaceous aerosols may also enhance the concentrations of cloud condensation nuclei. This paper summarizes observed concentrations of aerosols in remote continental and marine locations and provides estimates for the fine particle (D < 2.5 {mu}m) source rates of both OC and BC. The source rates for anthropogenic organic aerosols may be as large as the source rates for anthropogenic sulfate aerosols, suggesting a similar magnitude of direct forcing of climate. The role of BC in decreasing the amount of reflected solar radiation by OC and sulfates is discussed. The total estimated forcing depends on the source estimates for organic and black carbon aerosols which are highly uncertain. The role of organic aerosols acting as cloud condensation nuclei (CCN) is also described.

  2. Estimating the soil organic carbon content for European NUTS2 regions based on LUCAS data collection.

    PubMed

    Panagos, Panos; Ballabio, Cristiano; Yigini, Yusuf; Dunbar, Martha B

    2013-01-01

    Under the European Union Thematic Strategy for Soil Protection, the European Commission Directorate-General for the Environment and the European Environmental Agency (EEA) identified a decline in soil organic carbon and soil losses by erosion as priorities for the collection of policy relevant soil data at European scale. Moreover, the estimation of soil organic carbon content is of crucial importance for soil protection and for climate change mitigation strategies. Soil organic carbon is one of the attributes of the recently developed LUCAS soil database. The request for data on soil organic carbon and other soil attributes arose from an on-going debate about efforts to establish harmonized datasets for all EU countries with data on soil threats in order to support modeling activities and display variations in these soil conditions across Europe. In 2009, the European Commission's Joint Research Centre conducted the LUCAS soil survey, sampling ca. 20,000 points across 23 EU member states. This article describes the results obtained from analyzing the soil organic carbon data in the LUCAS soil database. The collected data were compared with the modeled European topsoil organic carbon content data developed at the JRC. The best fitted comparison was performed at NUTS2 level and showed underestimation of modeled data in southern Europe and overestimation in the new central eastern member states. There is a good correlation in certain regions for countries such as the United Kingdom, Slovenia, Italy, Ireland, and France. Here we assess the feasibility of producing comparable estimates of the soil organic carbon content at NUTS2 regional level for the European Union (EU27) and draw a comparison with existing modeled data. In addition to the data analysis, we suggest how the modeled data can be improved in future updates with better calibration of the model. PMID:23178783

  3. Analysis of isotope and organic carbon signatures in hillslope hydrographs

    NASA Astrophysics Data System (ADS)

    Dusek, Jaromir; Vogel, Tomas; Dohnal, Michal; Jankovec, Jakub; Sanda, Martin; Votrubova, Jana

    2015-04-01

    Headwater catchments are among the most important areas for investigation of isotope and carbon fluxes because their small sizes best enable separation of above- and below ground compartments for improved understanding of the respective transport mechanisms. So far, only few studies utilized stable isotope information in modeling and even fewer linked dissolved carbon fluxes to mixing or transport models. Stable isotopes of water and dissolved organic carbon provide basis for studying transport processes ranging from soil profile scale to hillslope and catchment scale. In this study, stormflow dynamics of oxygen-18 and dissolved organic carbon was analyzed using a physically based modeling approach. One-dimensional dual-continuum vertical flow and transport model, based on Richards and advection-dispersion equations, was used to simulate the subsurface processes during significant rainfall-runoff episodes of a summer season. Water flow and transport of solutes were assumed to take place in two mutually communicating continua, the soil matrix and the network of preferential pathways. Oxygen-18 and dissolved organic carbon were observed in soil water, stormflow discharge in the experimental hillslope trench, and stream discharge at the catchment outlet. In the present study, we analyzed the transformation of input solute signals into signatures observed in the stormflow discharge. The research was supported by the Czech Science Foundation Project No. 14-15201J.

  4. Isotopic Composition of Organic and Inorganic Carbon in Desert Biological Soil Crust Systems

    NASA Astrophysics Data System (ADS)

    Alexander, K.; Hartnett, H.; Anbar, A.; Beraldi, H.; Garcia-Pichel, F.

    2006-12-01

    Biological soil crusts (BSCs) are microbial communities that colonize soil surfaces in many arid regions. BSCs are important sources for fixed carbon and nitrogen in these ecosystems, and they greatly influence the structure, function, and appearance of desert soils. Biological activity of BSCs occurs during pulses of hydration requiring desert crusts to tolerate extremes in UV radiation, temperature, and desiccation. These characteristics make desert crusts unique systems that have received little consideration in the study of biogeochemical processes in extreme environments. This project investigates the impact of BSCs on carbon dynamics within desert soils. Soil cores ranging in depth from 8 to 12 cm were taken in March, 2006 from deserts near Moab, Utah. Two major BSC classes were identified: lichen-dominated (dark and pinnacled) soil crusts and cyanobacteria-dominated (light and flat) soil crusts. These two surface morphologies are related to the different biological communities. Carbon content and stable carbon isotopic composition were determined for the bulk carbon pool, as well as for the organic and inorganic carbon fractions of the soils. Expectedly, there was a net decrease in organic carbon content with depth (0.39-0.27 percent). Stable carbon isotope values for the organic fraction ranged from -5.8 per mil to -24.0 per mil (Avg: -14.4 per mil, S.D: 6.42 per mil). Stable carbon isotope values for the inorganic fraction ranged from 0.3 per mil to -3.6 per mil (Avg: -2.4 per mil, S.D.: 1.05 per mil). The variation in the isotopic composition of the organic carbon was due to a strong depletion below the surface soil value occurring between 3 and 5 cm depth, with an enrichment above the original surface value at depths below 6 to 10 cm. These data suggest that within desert soil crust systems the carbon isotopic signal is complex with both a clear biological imprint (lighter organic carbon) as well as evidence for some mechanism that results in

  5. DETERMINATION OF THE ORGANIC MASS TO ORGANIC CARBON RATIO IN IMPROVE SAMPLES. (R831086)

    EPA Science Inventory

    The ratio of organic mass (OM) to organic carbon (OC) in PM2.5 aerosols at US national parks in the IMPROVE network was estimated experimentally from solvent extraction of sample filters and from the difference between PM2.5 mass and chemical constituents...

  6. An isotopic study of biogeochemical relationships between carbonates and organic carbon in the Greenhorn Formation

    NASA Technical Reports Server (NTRS)

    Hayes, J. M.; Popp, Brian N.; Takigiku, Ray; Johnson, Marcus W.

    1989-01-01

    Carbon-isotopic compositions of total carbonate, inoceramid carbonate, micritic carbonate, secondary cements, total organic carbon, and geoporphyrins have been measured in 76 different beds within a 17-m interval of a core through the Greenhorn Formation, an interbedded limestone and calcareous shale unit of Cretaceous age from the Western Interior Seaway of North America. Results are considered in terms of variations in the processes of primary production and in secondary processes. It is shown that the porphyrin isotopic record reflects primary isotopic variations more closely than the TOC isotopic record and that, in these sediments, TOC is enriched in C-13 relative to its primary precursor by 0.6 to 2.8 percent. This enrichment is attributed to isotope effects within the consumer foodweb and is associated with respiratory heterotrophy. Variation in this secondary enrichment are correlated with variations in the isotopic composition of marine carbonate.

  7. COVER CROPS ENHANCE SOIL ORGANIC MATTER, CARBON DYNAMICS AND MICROBIOLOGICAL FUNCTION IN A MEDITERRANEAN VINEYARD AGROECOSYSTEM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Impacts of soil tillage and cover crops on soil carbon (C) dynamics and microbiological function were investigated in a vineyard grown in California’s Mediterranean climate. We 1) compared soil organic matter (SOM), C dynamics and microbiological activity of two cover crops [Trios 102 (Triticale x T...

  8. Primary and Secondary Organic Carbon Downwind of Mexico City

    SciTech Connect

    Yu, Xiao-Ying; Cary, R.; Laulainen, Nels S.

    2009-09-18

    In order to study particulate matter transport and transformation in the Megacity environment, fine particulate carbons were measured simultaneously at two supersites, suburban T1 and rural T2, downwind of Mexico City during the MILAGRO field campaign in March 2006. Organic carbon (OC), element carbon (EC), and total carbon (TC=OC+EC) were determined near real-time by the Sunset semi-continuous field analyzer at both sites. The semi-empirical EC tracer method was used to derive primary organic carbon (POC) and secondary organic carbon (SOC). Diurnal variations of primary and secondary carbons were observed at T1 and T2, which resulted from boundary layer inversion and impacted by local traffic patterns. The majority of organic carbons at T1 and T2 were secondary. The SOC% (SOC%=SOC/TC*100%) at T1 ranged from 1.2 - 100% with an average of 80.7 ± 14.4%. The SOC% at T2 ranged from 12.8 - 100% with an average of 80.1 ± 14.0%. The average EC to PM2.5 percentage (ECPM%=EC/PM2.5*100%)) and OCPM% were 6.0 % and 20.0% over the whole sampling time. The POC to PM percentage (POCPM%) and SOCPM% were 3.7% and 16.3%, respectively. The maximum ECPM% was 21.2%, and the maximum OCPM% was 57.2%. The maximum POCPM% was 12.9%, and the maximum SOC% was 49.7%. The SOC and POC during T1 to T2 transfer favourable meteorological conditions showed similar characteristics, which indicated that transport between the two supersites took place. Strong correlations between EC and carbon monoxide (CO) and odd nitrogens (NO and NOx) were observed at T1. This indicated that EC had proximate sources such as local traffic emissions. The EC/CO ratio derived by linear regression analysis when parameters are in μgC/m3 and μg/m3, respectively, was 0.0045. A strong correlation was also seen between OC and SOC vs. the sum of oxidants such as O3 and NO2 or O3, NO2 and SO2, suggesting the secondary nature of carbons observed at T1.

  9. Primary and secondary organic carbon downwind of Mexico City

    NASA Astrophysics Data System (ADS)

    Yu, X.-Y.; Cary, R. A.; Laulainen, N. S.

    2009-09-01

    In order to study particulate matter transport and transformation in the Megacity environment, fine particulate carbon was measured simultaneously at two supersites, suburban T1 and rural T2, downwind of Mexico City during the MILAGRO field campaign in March 2006. Organic carbon (OC), element carbon (EC), and total carbon (TC=OC+EC) were determined in near real-time using a Sunset semi-continuous OCEC field analyzer. The semi-empirical EC tracer method was used to derive primary organic carbon (POC) and secondary organic carbon (SOC). Diurnal variations of primary and secondary carbon were observed at T1 and T2, which resulted from boundary layer inversion and impacted by local traffic patterns. The majority of organic carbon particles at T1 and T2 were secondary. The SOCTC% (SOC%=SOC/TC×100%) at T1 ranged from 0.5-93.8% with an average of 63.5±17.2%. The SOCTC% at T2 ranged from 9.3-98.1% with an average of 67.4±12.4%. The average EC to PM2.5 percentage (ECPM%=EC/PM2.5×100%) and OCPM% were 6.0% and 20.0% over the whole sampling time at T1. The POC to PM percentage (POCPM%) and SOCPM% were 3.7% and 16.3%, respectively at the same site. The maximum ECPM% was 21.2%, and the maximum OCPM% was 57.2% at T1. The maximum POCPM% was 12.9%, and the maximum SOCPM% was 49.7% at T1. Comparison of SOC and POC at T1 and T2 showed similar characteristics under favorable meteorological conditions, which indicated that transport from T1 towards T2 took place. Strong correlations between EC and carbon monoxide (CO) and odd nitrogen species (NO and NOx) were observed at T1. This indicated that EC had nearby sources, such as local traffic emissions. The EC/CO ratio derived by linear regression analysis, with units of μg C/m3 and μg/m3, respectively, was 0.004 at T1. Correlations were also seen between OC and SOC vs. the sum of oxidants, such as O3 and NO2, suggesting the secondary nature of carbons observed at T1.

  10. Primary and secondary organic carbon downwind of Mexico City

    NASA Astrophysics Data System (ADS)

    Yu, X.-Y.; Cary, R. A.; Laulainen, N. S.

    2009-01-01

    In order to study particulate matter transport and transformation in the Megacity environment, fine particulate carbons were measured simultaneously at two supersites, suburban T1 and rural T2, downwind of Mexico City during the MILAGRO field campaign in March 2006. Organic carbon (OC), element carbon (EC), and total carbon (TC=OC+EC) were determined in near real-time using a Sunset semi-continuous OC/EC field analyzer. The semi-empirical EC tracer method was used to derive primary organic carbon (POC) and secondary organic carbon (SOC). Diurnal variations of primary and secondary carbons were observed at T1 and T2, which resulted from boundary layer inversion and impacted by local traffic patterns. The majority of organic carbon particles at T1 and T2 were secondary. The SOC% (SOC%=SOC/TC×100%) at T1 ranged from 1.2-100% with an average of 80.7±14.4%. The SOC% at T2 ranged from 12.8-100% with an average of 80.1±14.0%. The average EC to PM2.5 percentage (ECPM%=EC/PM2.5×100%) and OCPM% were 6.0% and 20.0% over the whole sampling time at T1. The POC to PM percentage (POCPM%) and SOCPM% were 3.7% and 16.3%, respectively at the same site. The maximum ECPM% was 21.2%, and the maximum OCPM% was 57.2% at T1. The maximum POCPM% was 12.9%, and the maximum SOCPM% was 49.7% at the suburban site. Comparison of SOC and POC at T1 and T2 showed similar characteristics under favorable meteorological conditions, which indicated that transport between the two supersites took place. Strong correlations between EC and carbon monoxide (CO) and odd nitrogen species (NO and NOx) were observed at T1. This indicated that EC had nearby sources, such as local traffic emissions. The EC/CO ratio derived by linear regression analysis, when parameters in μg C/m3 and μg/m3, respectively, was 0.0045 at T1. Correlations were also seen between OC and SOC vs. the sum of oxidants, such as O3 and NO2, suggesting the secondary nature of carbons observed at T1.

  11. Factors for Microbial Carbon Sources in Organic and Mineral Soils from Eastern United States Deciduous Forests

    NASA Astrophysics Data System (ADS)

    Stitt, C.; McFarlane, K. J.

    2013-12-01

    Forest soils represent a large portion of global terrestrial carbon; however, which soil carbon sources are used by soil microbes and respired as carbon dioxide (CO2) is not well known. This study will focus on characterizing microbial carbon sources from organic and mineral soils from four eastern United States deciduous forests using the unique radiocarbon tracer, 14C. Results from the dark incubation of the organic and mineral soils are heavily influenced by site characteristics when incubated at microbial optimal activity temperature. The sites with the most similarities are statically the same (p> 0.10). The sites with considerable differences in temperature, texture, and location are statically different concluding that site characteristics play a role in soil respiration.

  12. Soil Organic Carbon Dynamics under Conservation Agricultural Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil organic carbon (SOC) is a key element in the valuation of natural resources and the evaluation of how management affects soil quality and ecosystem services derived from soil. This paper describes a summary of some recent research aimed at understanding how SOC contributes to (a) various soil ...

  13. Impacts of soil organic carbon on soil physical behavior

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management-induced changes in soil organic carbon (SOC) concentration can affect soil physical behavior. Specifically, removal of crop residues as biofuel may thus adversely affect soil attributes by reducing SOC concentration as crop residues are the main source of SOC. Implications of crop residue...

  14. Redistribution of soil and soil organic carbon on agricultural landscapes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Patterns of soil organic carbon (SOC) vary widely across the landscape leading to large uncertainties in the SOC budgets for agricultural systems especially for landscapes where water, tillage, and wind erosion redistributes soil and SOC across the landscape. It is often assumed that soil erosion r...

  15. Photoproduction of Carbon Monoxide from Natural Organic Matter

    EPA Science Inventory

    Pioneering studies by Valentine provided early kinetic results that used carbon monoxide (CO) production to evaluate the photodecomposition of aquatic natural organic matter (NOM) . (ES&T 1993 27 409-412). Comparatively few kinetic studies have been conducted of the photodegradat...

  16. Isotope tracers of organic carbon during artificial recharge

    SciTech Connect

    Davisson, M.L.

    1998-02-09

    This project developed an analytical technique for measuring the isotope abundance for 14C and 13C in total organic carbon (TOC) in order to test whether these measurements can trace TOC interaction with sedimentary material at the bottom of rivers and lakes, soils, and subsurface aquifer rocks.

  17. REMOTE MONITORING OF ORGANIC CARBON IN SURFACE WATERS

    EPA Science Inventory

    This study shows that the intensity of the Raman normalized fluorescence emission induced in surface waters by ultraviolet radiation can be used to provide a unique remote sensing capability for airborne monitoring the concentration of dissolved organic carbon (DOC). Trace concen...

  18. Fenton- and Persulfate-driven Regeneration of Contaminant-spent Granular Activated Carbon

    EPA Science Inventory

    Fenton- or persulfate-driven chemical oxidation regeneration of spent granular activated carbon (GAC) involves the combined, synergistic use of two treatment technologies: adsorption of organic chemicals onto GAC and chemical oxidation regeneration of the spent-GAC. Environmental...

  19. Potential for Carbon Sequestration using Organic Amendments on Rangeland Soils

    NASA Astrophysics Data System (ADS)

    Ryals, R.; Silver, W. L.

    2009-12-01

    Managed rangelands represent a geographically large land-use footprint and thus have considerable potential to sequester carbon (C) in soil through changes in management practices. Organic amendments are frequently added to agricultural and rangeland soils in an effort to improve fertility and yield, yet little is known about their impact on greenhouse gas dynamics and soil biogeochemical dynamics, especially in rangeland soils. This research aims to explore the effects of organic amendments on soil chemical and physical properties, plant inputs, and soil C and N dynamics in managed rangeland ecosystems. Our research uses field manipulations at two Mediterranean grassland ecosystems replicated within and across bioclimatic zones: the Sierra Foothills Research and Extension Center (SFREC) in Browns Valley, CA and the Nicasio Native Grass Ranch in Nicasio, CA. Both sites are dominated by annual grasses and are moderately grazed by cattle. Three replicate blocks at each site contain 60m x 25m treatment plots (organic amendments and control) with 5m buffer strips. Organic amendments were applied at a level of 14 MgC/ha (equivalent to a 1.27cm surface dressing) at the beginning of the wet season (December 2008). During the wet season (October through June), carbon dioxide (CO2) flux was measured weekly using a LI-8100, while fluxes of methane (CH4) and nitrous oxide (N2O) were measured biweekly using static flux chambers. During the dry season (June through September), fluxes were measured biweekly and monthly, respectively. Soil organic C (SOC) and nitrogen (N) were measured prior to treatment and seven months following treatment at 0-10, 10-30, 30-50, and 50-100 cm depths. Soil moisture and temperature were measured continuously. Changes in oxidative and hydrolytic extracellular enzyme activities are also being explored. After the first year of management, both sites responded similarly to treatments in both trend and magnitude. For example, at SFREC, total soil

  20. Organic Matter Quality and its Influence on Carbon Turnover and Stabilization in Northern Peatlands

    NASA Astrophysics Data System (ADS)

    Turetsky, M. R.; Wieder, R. K.

    2002-12-01

    Peatlands cover 3-5 % of the world's ice-free land area, but store about 33 % of global terrestrial soil carbon. Peat accumulation in northern regions generally is controlled by slow decomposition, which may be limited by cold temperatures and water-logging. Poor organic matter quality also may limit decay, and microbial activity in peatlands likely is regulated by the availability of labile carbon and/or nutrients. Conversely, carbon in recalcitrant soil structures may be chemically protected from microbial decay, particularly in peatlands where carbon can be buried in anaerobic soils. Soil organic matter quality is controlled by plant litter chemical composition and the susceptibility of organic compounds to decomposition through time. There are a number of techniques available for characterizing organic quality, ranging from chemical proximate or elemental analysis to more qualitative methods such as nuclear magenetic resonance, pyrolysis/mass spectroscopy, and Fourier transform infrared spectroscopy. We generally have relied on proximate analysis for quantitative determination of several organic fractions (i.e., water-soluble carbohydrates, soluble nonpolars, water-soluble phenolics, holocellulose, and acid insoluble material). Our approaches to studying organic matter quality in relation to C turnover in peatlands include 1) 14C labelling of peatland vegetation along a latitudinal gradient in North America, allowing us to follow the fate of 14C tracer in belowground organic fractions under varying climates, 2) litter bag studies focusing on the role of individual moss species in litter quality and organic matter decomposition, and 3) laboratory incubations of peat to explore relationships between organic matter quality and decay. These studies suggest that proximate organic fractions vary in lability, but that turnover of organic matter is influenced both by plant species and climate. Across boreal peatlands, measures of soil recalcitrance such as acid

  1. Spatial distribution of soil organic carbon stocks in France

    NASA Astrophysics Data System (ADS)

    Martin, M. P.; Wattenbach, M.; Smith, P.; Meersmans, J.; Jolivet, C.; Boulonne, L.; Arrouays, D.

    2011-05-01

    Soil organic carbon plays a major role in the global carbon budget, and can act as a source or a sink of atmospheric carbon, thereby possibly influencing the course of climate change. Changes in soil organic carbon (SOC) stocks are now taken into account in international negotiations regarding climate change. Consequently, developing sampling schemes and models for estimating the spatial distribution of SOC stocks is a priority. The French soil monitoring network has been established on a 16 km × 16 km grid and the first sampling campaign has recently been completed, providing around 2200 measurements of stocks of soil organic carbon, obtained through an in situ composite sampling, uniformly distributed over the French territory. We calibrated a boosted regression tree model on the observed stocks, modelling SOC stocks as a function of other variables such as climatic parameters, vegetation net primary productivity, soil properties and land use. The calibrated model was evaluated through cross-validation and eventually used for estimating SOC stocks for mainland France. Two other models were calibrated on forest and agricultural soils separately, in order to assess more precisely the influence of pedo-climatic variables on SOC for such soils. The boosted regression tree model showed good predictive ability, and enabled quantification of relationships between SOC stocks and pedo-climatic variables (plus their interactions) over the French territory. These relationships strongly depended on the land use, and more specifically, differed between forest soils and cultivated soil. The total estimate of SOC stocks in France was 3.260 ± 0.872 PgC for the first 30 cm. It was compared to another estimate, based on the previously published European soil organic carbon and bulk density maps, of 5.303 PgC. We demonstrate that the present estimate might better represent the actual SOC stock distributions of France, and consequently that the previously published approach at the

  2. Inorganic carbon and fossil organic carbon are source of bias for quantification of sequestered carbon in mine spoil

    NASA Astrophysics Data System (ADS)

    Vindušková, Olga; Frouz, Jan

    2016-04-01

    Carbon sequestration in mine soils has been studied as a possibility to mitigate the rising atmospheric CO2 levels and to improve mine soil quality (Vindu\\vsková and Frouz, 2013). Moreover, these soils offer an unique opportunity to study soil carbon dynamics using the chronosequence approach (using a set of sites of different age on similar parent material). However, quantification of sequestered carbon in mine soils is often complicated by fossil organic carbon (e.g., from coal or kerogen) or inorganic carbon present in the spoil. We present a methodology for quantification of both of these common constituents of mine soils. Our recommendations are based on experiments done on post-mining soils in Sokolov basin, Czech Republic. Here, fossil organic carbon is present mainly as kerogen Type I and II and represents 2-6 wt.% C in these soils. Inorganic carbon in these soils is present mainly as siderite (FeCO3), calcite (CaCO3), and dolomite (CaMg(CO3)2). All of these carbonates are often found in the overburden of coal seams thus being a common constituent of post-mining soils in the world. Vindu\\vsková O, Frouz J, 2013. Soil carbon accumulation after open-cast coal and oil shale mining in Northern Hemisphere: a quantitative review. ENVIRONMENTAL EARTH SCIENCES, 69: 1685-1698. Vindu\\vsková O, Dvořáček V, Prohasková A, Frouz J. 2014. Distinguishing recent and fossil organic matter - A critical step in evaluation of post-mining soil development - using near infrared spectroscopy. ECOLOGICAL ENGINEERING. 73: 643-648. Vindu\\vsková O, Sebag D, Cailleau G, Brus J, Frouz J. 2015. Methodological comparison for quantitative analysis of fossil and recently derived carbon in mine soils with high content of aliphatic kerogen. ORGANIC GEOCHEMISTRY, 89-90:14-22.

  3. Hyperspectral Analysis of Soil Nitrogen, Carbon, Carbonate, and Organic Matter Using Regression Trees

    PubMed Central

    Gmur, Stephan; Vogt, Daniel; Zabowski, Darlene; Moskal, L. Monika

    2012-01-01

    The characterization of soil attributes using hyperspectral sensors has revealed patterns in soil spectra that are known to respond to mineral composition, organic matter, soil moisture and particle size distribution. Soil samples from different soil horizons of replicated soil series from sites located within Washington and Oregon were analyzed with the FieldSpec Spectroradiometer to measure their spectral signatures across the electromagnetic range of 400 to 1,000 nm. Similarity rankings of individual soil samples reveal differences between replicate series as well as samples within the same replicate series. Using classification and regression tree statistical methods, regression trees were fitted to each spectral response using concentrations of nitrogen, carbon, carbonate and organic matter as the response variables. Statistics resulting from fitted trees were: nitrogen R2 0.91 (p < 0.01) at 403, 470, 687, and 846 nm spectral band widths, carbonate R2 0.95 (p < 0.01) at 531 and 898 nm band widths, total carbon R2 0.93 (p < 0.01) at 400, 409, 441 and 907 nm band widths, and organic matter R2 0.98 (p < 0.01) at 300, 400, 441, 832 and 907 nm band widths. Use of the 400 to 1,000 nm electromagnetic range utilizing regression trees provided a powerful, rapid and inexpensive method for assessing nitrogen, carbon, carbonate and organic matter for upper soil horizons in a nondestructive method. PMID:23112620

  4. Hyperspectral analysis of soil nitrogen, carbon, carbonate, and organic matter using regression trees.

    PubMed

    Gmur, Stephan; Vogt, Daniel; Zabowski, Darlene; Moskal, L Monika

    2012-01-01

    The characterization of soil attributes using hyperspectral sensors has revealed patterns in soil spectra that are known to respond to mineral composition, organic matter, soil moisture and particle size distribution. Soil samples from different soil horizons of replicated soil series from sites located within Washington and Oregon were analyzed with the FieldSpec Spectroradiometer to measure their spectral signatures across the electromagnetic range of 400 to 1,000 nm. Similarity rankings of individual soil samples reveal differences between replicate series as well as samples within the same replicate series. Using classification and regression tree statistical methods, regression trees were fitted to each spectral response using concentrations of nitrogen, carbon, carbonate and organic matter as the response variables. Statistics resulting from fitted trees were: nitrogen R(2) 0.91 (p < 0.01) at 403, 470, 687, and 846 nm spectral band widths, carbonate R(2) 0.95 (p < 0.01) at 531 and 898 nm band widths, total carbon R(2) 0.93 (p < 0.01) at 400, 409, 441 and 907 nm band widths, and organic matter R(2) 0.98 (p < 0.01) at 300, 400, 441, 832 and 907 nm band widths. Use of the 400 to 1,000 nm electromagnetic range utilizing regression trees provided a powerful, rapid and inexpensive method for assessing nitrogen, carbon, carbonate and organic matter for upper soil horizons in a nondestructive method. PMID:23112620

  5. The biomass derived activated carbon for supercapacitor

    NASA Astrophysics Data System (ADS)

    Senthilkumar, S. T.; Selvan, R. Kalai; Melo, J. S.

    2013-06-01

    In this work, the activated carbon was prepared from biowaste of Eichhornia crassipes by chemical activation method using KOH as the activating agent at various carbonization temperatures (600 °C, 700 °C and 800 °C). The disordered nature, morphology and surface functional groups of ACs were examined by XRD, SEM and FT-IR. The electrochemical properties of AC electrodes were studied in 1M H2SO4 in the potential range of -0.2 to 0.8 V using cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) techniques in a three electrode system. Subsequently, the fabricated supercapacitor using AC electrode delivered the higher specific capacitance and energy density of 509 F/g at current density of 1 mA/cm2 and 17 Wh/kg at power density of 0.416 W/g.

  6. Activation and micropore structure determination of activated carbon-fiber composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.

    1997-09-05

    Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. These novel monolithic adsorbents can be produced in single pieces to a given size and shape. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The carbon fiber composites are produced at the ORNL and activated at the CAER using different methods, with the aims of producing a uniform degree of activation, and of closely controlling pore structure and adsorptive properties. The main focus of the present work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites and produce controlled pore structures. Several environmental applications have been explored for the activated carbon fiber composites. One of these was to evaluate the activated composites for the separation of CH{sub 4}-CO{sub 2} mixtures, and an apparatus was constructed specifically for this purpose. The composites were further evaluated in the cyclic recovery of volatile organics. The activated carbon fiber composites have also been tested for possible water treatment applications by studying the adsorption of sodium pentachlorophenolate, PCP.

  7. Supercapacitor Electrodes from Activated Carbon Monoliths and Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Dolah, B. N. M.; Othman, M. A. R.; Deraman, M.; Basri, N. H.; Farma, R.; Talib, I. A.; Ishak, M. M.

    2013-04-01

    Binderless monoliths of supercapacitor electrodes were prepared by the carbonization (N2) and activation (CO2) of green monoliths (GMs). GMs were made from mixtures of self-adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches and a combination of 5 & 6% KOH and 0, 5 & 6% carbon nanotubes (CNTs) by weight. The electrodes from GMs containing CNTs were found to have lower specific BET surface area (SBET). The electrochemical behavior of the supercapacitor fabricated using the prepared electrodes were investigated by electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). In general an addition of CNTs into the GMs reduces the equivalent series resistance (ESR) value of the cells. A cell fabricated using electrodes from GM with 5% CNT and 5% KOH was found to have the largest reduction of ESR value than that from the others GMs containing CNT. The cell has steeper Warburg's slope than that from its respective non-CNT GM, which reflect the smaller resistance for electrolyte ions to move into pores of electrodes despite these electrodes having largest reduction in specific BET surface area. The cell also has the smallest reduction of specific capacitance (Csp) and maintains the specific power range despite a reduction in the specific energy range due to the CNT addition.

  8. Latitudinal Gradients in Degradation of Marine Dissolved Organic Carbon

    PubMed Central

    Arnosti, Carol; Steen, Andrew D.; Ziervogel, Kai; Ghobrial, Sherif; Jeffrey, Wade H.

    2011-01-01

    Heterotrophic microbial communities cycle nearly half of net primary productivity in the ocean, and play a particularly important role in transformations of dissolved organic carbon (DOC). The specific means by which these communities mediate the transformations of organic carbon are largely unknown, since the vast majority of marine bacteria have not been isolated in culture, and most measurements of DOC degradation rates have focused on uptake and metabolism of either bulk DOC or of simple model compounds (e.g. specific amino acids or sugars). Genomic investigations provide information about the potential capabilities of organisms and communities but not the extent to which such potential is expressed. We tested directly the capabilities of heterotrophic microbial communities in surface ocean waters at 32 stations spanning latitudes from 76°S to 79°N to hydrolyze a range of high molecular weight organic substrates and thereby initiate organic matter degradation. These data demonstrate the existence of a latitudinal gradient in the range of complex substrates available to heterotrophic microbial communities, paralleling the global gradient in bacterial species richness. As changing climate increasingly affects the marine environment, changes in the spectrum of substrates accessible by microbial communities may lead to shifts in the location and rate at which marine DOC is respired. Since the inventory of DOC in the ocean is comparable in magnitude to the atmospheric CO2 reservoir, such a change could profoundly affect the global carbon cycle. PMID:22216139

  9. Magnetite impregnation effects on the sorbent properties of activated carbons and biochars.

    PubMed

    Han, Zhantao; Sani, Badruddeen; Mrozik, Wojciech; Obst, Martin; Beckingham, Barbara; Karapanagioti, Hrissi K; Werner, David

    2015-03-01

    This paper discusses the sorbent properties of magnetic activated carbons and biochars produced by wet impregnation with iron oxides. The sorbents had magnetic susceptibilities consistent with theoretical predictions for carbon-magnetite composites. The high BET surface areas of the activated carbons were preserved in the synthesis, and enhanced for one low surface area biochar by dissolving carbonates. Magnetization decreased the point of zero charge. Organic compound sorption correlated strongly with BET surface areas for the pristine and magnetized materials, while metal cation sorption did not show such a correlation. Strong sorption of the hydrophobic organic contaminant phenanthrene to the activated carbon or biochar surfaces was maintained following magnetite impregnation, while phenol sorption was diminished, probably due to enhanced carbon oxidation. Copper, zinc and lead sorption to the activated carbons and biochars was unchanged or slightly enhanced by the magnetization, and iron oxides also contributed to the composite metal sorption capacity. While a magnetic biochar with 219 ± 3.7 m(2)/g surface area nearly reached the very strong organic pollutant binding capacity of the two magnetic activated carbons, a magnetic biochar with 68 ± 2.8 m(2)/g surface area was the best metal sorbent. Magnetic biochars thus hold promise as more sustainable alternatives to coal-derived magnetic activated carbons. PMID:25555224

  10. How Somatic Adult Tissues Develop Organizer Activity.

    PubMed

    Vogg, Matthias C; Wenger, Yvan; Galliot, Brigitte

    2016-01-01

    The growth and patterning of anatomical structures from specific cellular fields in developing organisms relies on organizing centers that instruct surrounding cells to modify their behavior, namely migration, proliferation, and differentiation. We discuss here how organizers can form in adult organisms, a process of utmost interest for regenerative medicine. Animals like Hydra and planarians, which maintain their shape and fitness thanks to a highly dynamic homeostasis, offer a useful paradigm to study adult organizers in steady-state conditions. Beside the homeostatic context, these model systems also offer the possibility to study how organizers form de novo from somatic adult tissues. Both extracellular matrix remodeling and caspase activation play a key role in this transition, acting as promoters of organizer formation in the vicinity of the wound. Their respective roles and the crosstalk between them just start to be deciphered. PMID:26970630

  11. Organic Carbon Storage in Four Ecosystem Types in the Karst Region of Southwestern China

    PubMed Central

    Wang, Shijie; Guo, Ke; Yang, Jun; Zhang, Xinshi; Li, Guoqing

    2013-01-01

    Karst ecosystems are important landscape types that cover about 12% of the world's land area. The role of karst ecosystems in the global carbon cycle remains unclear, due to the lack of an appropriate method for determining the thickness of the solum, a representative sampling of the soil and data of organic carbon stocks at the ecosystem level. The karst region in southwestern China is the largest in the world. In this study, we estimated biomass, soil quantity and ecosystem organic carbon stocks in four vegetation types typical of karst ecosystems in this region, shrub grasslands (SG), thorn shrubbery (TS), forest - shrub transition (FS) and secondary forest (F). The results showed that the biomass of SG, TS, FS, and F is 0.52, 0.85, 5.9 and 19.2 kg m−2, respectively and the corresponding organic cabon storage is 0.26, 0.40, 2.83 and 9.09 kg m−2, respectively. Nevertheless, soil quantity and corresponding organic carbon storage are very small in karst habitats. The quantity of fine earth overlaying the physical weathering zone of the carbonate rock of SG, TS, FS and F is 38.10, 99.24, 29.57 and 61.89 kg m−2, respectively, while the corresponding organic carbon storage is only 3.34, 4.10, 2.37, 5.25 kg m−2, respectively. As a whole, ecosystem organic carbon storage of SG, TS, FS, and F is 3.81, 4.72, 5.68 and 15.1 kg m−2, respectively. These are very low levels compared to other ecosystems in non-karst areas. With the restoration of degraded vegetation, karst ecosystems in southwestern China may play active roles in mitigating the increasing CO2 concentration in the atmosphere. PMID:23451047

  12. New insights into the organic carbon export in the Mediterranean Sea from 3-D modeling

    NASA Astrophysics Data System (ADS)

    Guyennon, A.; Baklouti, M.; Diaz, F.; Palmieri, J.; Beuvier, J.; Lebaupin-Brossier, C.; Arsouze, T.; Béranger, K.; Dutay, J.-C.; Moutin, T.

    2015-12-01

    The Mediterranean Sea is one of the most oligotrophic regions of the oceans, and nutrients have been shown to limit both phytoplankton and bacterial activities, resulting in a potential major role of dissolved organic carbon (DOC) export in the biological pump. Strong DOC accumulation in surface waters is already well documented, though measurements of DOC stocks and export flux are still sparse and associated with major uncertainties. This study provides the first basin-scale overview and analysis of organic carbon stocks and export fluxes in the Mediterranean Sea through a modeling approach based on a coupled model combining a mechanistic biogeochemical model (Eco3M-MED) and a high-resolution (eddy-resolving) hydrodynamic simulation (NEMO-MED12). The model is shown to reproduce the main spatial and seasonal biogeochemical characteristics of the Mediterranean Sea. Model estimations of carbon export are also of the same order of magnitude as estimations from in situ observations, and their respective spatial patterns are mutually consistent. Strong differences between the western and eastern basins are evidenced by the model for organic carbon export. Though less oligotrophic than the eastern basin, the western basin only supports 39 % of organic carbon (particulate and dissolved) export. Another major result is that except for the Alboran Sea, the DOC contribution to organic carbon export is higher than that of particulate organic carbon (POC) throughout the Mediterranean Sea, especially in the eastern basin. This paper also investigates the seasonality of DOC and POC exports as well as the differences in the processes involved in DOC and POC exports in light of intracellular quotas. Finally, according to the model, strong phosphate limitation of both bacteria and phytoplankton growth is one of the main drivers of DOC accumulation and therefore of export.

  13. Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon

    NASA Astrophysics Data System (ADS)

    Neubauer, S. C.; Franklin, R. B.; Berrier, D. J.

    2013-12-01

    Environmental perturbations in wetlands affect the integrated plant-microbial-soil system, causing biogeochemical responses that can manifest at local to global scales. The objective of this study was to determine how saltwater intrusion affects carbon mineralization and greenhouse gas production in coastal wetlands. Working with tidal freshwater marsh soils that had experienced ~ 3.5 yr of in situ saltwater additions, we quantified changes in soil properties, measured extracellular enzyme activity associated with organic matter breakdown, and determined potential rates of anaerobic carbon dioxide (CO2) and methane (CH4) production. Soils from the field plots treated with brackish water had lower carbon content and higher C : N ratios than soils from freshwater plots, indicating that saltwater intrusion reduced carbon availability and increased organic matter recalcitrance. This was reflected in reduced activities of enzymes associated with the hydrolysis of cellulose and the oxidation of lignin, leading to reduced rates of soil CO2 and CH4 production. The effects of long-term saltwater additions contrasted with the effects of short-term exposure to brackish water during three-day laboratory incubations, which increased rates of CO2 production but lowered rates of CH4 production. Collectively, our data suggest that the long-term effect of saltwater intrusion on soil CO2 production is indirect, mediated through the effects of elevated salinity on the quantity and quality of autochthonous organic matter inputs to the soil. In contrast, salinity, organic matter content, and enzyme activities directly influence CH4 production. Our analyses demonstrate that saltwater intrusion into tidal freshwater marshes affects the entire process of carbon mineralization, from the availability of organic carbon through its terminal metabolism to CO2 and/or CH4, and illustrate that long-term shifts in biogeochemical functioning are not necessarily consistent with short

  14. Saltwater intrusion into tidal freshwater marshes alters the biogeochemical processing of organic carbon

    NASA Astrophysics Data System (ADS)

    Neubauer, S. C.; Franklin, R. B.; Berrier, D. J.

    2013-07-01

    Environmental perturbations in wetlands affect the integrated plant-microbial-soil system, causing biogeochemical responses that can manifest at local to global scales. The objective of this study was to determine how saltwater intrusion affects carbon mineralization and greenhouse gas production in coastal wetlands. Working with tidal freshwater marsh soils that had experienced roughly 3.5 yr of in situ saltwater additions, we quantified changes in soil properties, measured extracellular enzyme activity associated with organic matter breakdown, and determined potential rates of anaerobic carbon dioxide (CO2) and methane (CH4) production. Soils from the field plots treated with brackish water had lower carbon content and higher C : N ratios than soils from freshwater plots, indicating that saltwater intrusion reduced carbon availability and increased organic matter recalcitrance. This was reflected in reduced activities of enzymes associated with the hydrolysis of cellulose and the oxidation of lignin, leading to reduced rates of soil CO2 and CH4 production. The effects of long-term saltwater additions contrasted with the effects of short-term exposure to brackish water during three-day laboratory incubations, which increased rates of CO2 production but lowered rates of CH4 production. Collectively, our data suggest that the long-term effect of saltwater intrusion on soil CO2 production is indirect, mediated through the effects of elevated salinity on the quantity and quality of autochthonous organic matter inputs to the soil. In contrast, salinity, organic matter content, and enzyme activities directly influence CH4 production. Our analyses demonstrate that saltwater intrusion into tidal freshwater marshes affects the entire process of carbon mineralization, from the availability of organic carbon through its terminal metabolism to CO2 and/or CH4, and illustrate that long-term shifts in biogeochemical functioning are not necessarily consistent with short

  15. Energy costs of carbon dioxide concentrating mechanisms in aquatic organisms.

    PubMed

    Raven, John A; Beardall, John; Giordano, Mario

    2014-09-01

    Minimum energy (as photon) costs are predicted for core reactions of photosynthesis, for photorespiratory metabolism in algae lacking CO2 concentrating mechanisms (CCMs) and for various types of CCMs; in algae, with CCMs; allowance was made for leakage of CO2 from the internal pool. These predicted values are just compatible with the minimum measured photon costs of photosynthesis in microalgae and macroalgae lacking or expressing CCMs. More energy-expensive photorespiration, for example for organisms using Rubiscos with lower CO2-O2 selectivity coefficients, would be less readily accommodated within the lowest measured photon costs of photosynthesis by algae lacking CCMs. The same applies to the cases of CCMs with higher energy costs of active transport of protons or inorganic carbon species, or greater allowance for significant leakage from the accumulated intracellular pool of CO2. High energetic efficiency can involve a higher concentration of catalyst to achieve a given rate of reaction, adding to the resource costs of growth. There are no obvious mechanistic interpretations of the occurrence of CCMs algae adapted to low light and low temperatures using the rationales adopted for the occurrence of C4 photosynthesis in terrestrial flowering plants. There is an exception for cyanobacteria with low-selectivity Form IA or IB Rubiscos, and those dinoflagellates with low-selectivity Form II Rubiscos, for which very few natural environments have high enough CO2:O2 ratios to allow photosynthesis in the absence of CCMs. PMID:24390639

  16. Fluxes of dissolved organic carbon from Chesapeake Bay sediments

    SciTech Connect

    Burdige, D.J.; Homstead, J. )

    1994-08-01

    Benthic fluxes of dissolved organic carbon (DOC) were measured over an annual cycle at two contrasting sites in Chesapeake Bay. At an organic-rich, sulfidic site in the mesohaline portion of the Bay (site M) DOC fluxes from the sediments ranged from 1.4 to 2.9 mmol/m[sup 2]/d. Measured benthic DOC fluxes at site M corresponded to [approximately]3-13% of the depth-integrated benthic C remineralization rates ([Sigma]OCR), and agreed well with calculated diffusive DOC fluxes based on porewater DOC profiles. This agreement suggests that DOC fluxes from site M sediments were likely controlled by molecular diffusion. The second site that was studied is a heavily bioturbated site in the southern Bay (site S). The activity of macrobenthos did not appear to enhance DOC fluxes from these sediments, since measured benthic DOC fluxes (>0.5 mmol/m[sup 2]/d) were lower than those at site M. The ratios of benthic DOC fluxes to [Sigma]OCR values at site S were also slightly smaller than those observed at site M. Benthic DOC fluxes from Chesapeake Bay sediments do not appear to significantly affect the transport of DOC through this estuary, although uncertainties in the reactivity of DOC in estuaries makes this conclusion somewhat tentative at this time. However, when these results are used to make a lower limit estimate of the globally integrated benthic DOC flux from marine sediments, a value similar to that previously calculated by Burdige et al. is obtained. This observation further supports suggestions in this paper about the importance of benthic DOC fluxes in the oceanic C cycle.

  17. Aqueous adsorption and removal of organic contaminants by carbon nanotubes.

    PubMed

    Yu, Jin-Gang; Zhao, Xiu-Hui; Yang, Hua; Chen, Xiao-Hong; Yang, Qiaoqin; Yu, Lin-Yan; Jiang, Jian-Hui; Chen, Xiao-Qing

    2014-06-01

    Organic contaminants have become one of the most serious environmental problems, and the removal of organic contaminants (e.g., dyes, pesticides, and pharmaceuticals/drugs) and common industrial organic wastes (e.g., phenols and aromatic amines) from aqueous solutions is of special concern because they are recalcitrant and persistent in the environment. In recent years, carbon nanotubes (CNTs) have been gradually applied to the removal of organic contaminants from wastewater through adsorption processes. This paper reviews recent progress (145 studies published from 2010 to 2013) in the application of CNTs and their composites for the removal of toxic organic pollutants from contaminated water. The paper discusses removal efficiencies and adsorption mechanisms as well as thermodynamics and reaction kinetics. CNTs are predicted to have considerable prospects for wider application to wastewater treatment in the future. PMID:24657369

  18. Enhanced photocatalytic activity of titanium dioxide by nut shell carbon.

    PubMed

    Shi, Xiaoliang; Wang, Sheng; Dong, Xuebin; Zhang, Qiaoxin

    2009-08-15

    Nut shell carbon (NSC)-nanotitanium dioxide (TiO(2)) composites were prepared by sol-gel method. Photocatalytic activity on degradation of dye Rhodamine B was studied. X-ray diffraction, field emission scanning electron microscopy, Brunauer-Emmett-Teller surface area, pore size distribution, ultraviolet-vis light absorption spectrum, and photoluminescence spectrum were carried out to characterize the composite catalyst. The results indicated that the photocatalytic activity of NSC-nano-TiO(2) composites was much higher than P25 (Degussa). NSC could greatly absorb the organic substance and oxygen of solution because of its large surface area. PMID:19200653

  19. Formation of Intermediate Carbon Phases in Hydrothermal Abiotic Organic Synthesis

    NASA Astrophysics Data System (ADS)

    Fu, Q.; Foustoukos, D. I.; Seyfried, W. E.

    2005-12-01

    With high dissolved concentrations of methane and other hydrocarbon species revealed at the Rainbow and Logatchev vent systems on the Mid-Atlantic Ridge, it is essential to better understand reaction pathways of abiotic organic synthesis in hydrothermal systems. Thus, we performed a hydrothermal carbon reduction experiment with 13C labeled carbon source at temperature and pressure conditions that approximate those inferred for ultramafic-hosted hydrothermal systems. Pentlandite, a common alteration mineral phase in subseafloor reaction zones, acted as a potential catalyst. Surface analysis techniques (XPS and ToF-SIMS) were used to characterize intermediate carbon species within this process. Time series dissolved H2 and H2S concentrations indicated thermodynamic equilibrium. Dissolved H2 and H2S concentrations of 13 and 2 mmol/kg, respectively, are approximately equivalent to measured values in Rainbow and Logatchev hydrothermal systems. Isotopically pure 13C methane and other alkane species (C2H6 and C3H8) were observed throughout the experiment, and attained steady state conditions. XPS analysis on mineral product surface indicated carbon enrichment on mineral surface following reaction. The majority of surface carbon involves species containing C-C or C-H bonds, such as alkyl or methylene groups. Alcohol and carboxyl groups in fewer amounts were also observed. ToF-SIMS analysis, which can offer isotope identification with high mass resolution, showed that most of these carbon species were 13C-labeled. Unlike gas phase Fischer-Tropsch synthesis, no carbide was observed on mineral product surface during the experiment. Therefore, a reaction pathway is proposed for formation of dissolved linear alkane species in hydrothermal abiotic organic synthesis, where oxygen-bearing organic compounds are expected to form in aqueous products by way of alcohol and carboxyl groups on mineral catalyst surface.

  20. Chemical and carbon isotopic composition of dissolved organic carbon in a regional confined methanogenic aquifer

    USGS Publications Warehouse

    Aravena, R.; Wassenaar, L.I.; Spiker, E. C.

    2004-01-01

    This study demonstrates the advantage of a combined use of chemical and isotopic tools to understand the dissolved organic carbon (DOC) cycle in a regional confined methanogenic aquifer. DOC concentration and carbon isotopic data demonstrate that the soil zone is a primary carbon source of groundwater DOC in areas close to recharge zones. An in-situ DOC source linked to organic rich sediments present in the aquifer matrix is controlling the DOC pool in the central part of the groundwater flow system. DOC fractions, 13C-NMR on fulvic acids and 14C data on DOC and CH4 support the hypothesis that the in-situ DOC source is a terrestrial organic matter and discard the Ordovician bedrock as a source of DOC. ?? 2004 Taylor and Francis Ltd.

  1. Modeling stable isotope and organic carbon in hillslope stormflow

    NASA Astrophysics Data System (ADS)

    Dusek, Jaromir; Vogel, Tomas; Dohnal, Michal; Marx, Anne; Jankovec, Jakub; Sanda, Martin; Votrubova, Jana; Barth, Johannes A. C.; Cislerova, Milena

    2016-04-01

    Reliable prediction of water movement and fluxes of dissolved substances (such as stable isotopes and organic carbon) at both the hillslope and the catchment scales remains a challenge due to complex boundary conditions and soil spatial heterogeneity. In addition, microbially mediated transformations of dissolved organic carbon (DOC) are known to affect balance of DOC in soils, hence the transformations need to be included in a conceptual model of a DOC transport. So far, only few studies utilized stable isotope information in modeling and even fewer linked dissolved carbon fluxes to mixing and/or transport models. In this study, stormflow dynamics of oxygen-18 isotope and dissolved organic carbon was analyzed using a physically based modeling approach. One-dimensional dual-continuum vertical flow and transport model, based on Richards and advection-dispersion equations, was used to simulate the subsurface transport processes in a forest soil during several observed rainfall-runoff episodes. The transport of heat in the soil profile was described by conduction-advection equation. Water flow and transport of solutes and heat were assumed to take place in two mutually communicating porous domains, the soil matrix and the network of preferential pathways. The rate of microbial transformations of DOC was assumed to depend on soil water content and soil temperature. Oxygen-18 and dissolved organic carbon concentrations were observed in soil pore water, hillslope stormflow (collected in the experimental hillslope trench), and stream discharge (at the catchment outlet). The modeling was used to analyze the transformation of input solute signals into output hillslope signals observed in the trench stormflow. Signatures of oxygen-18 isotope in hillslope stormflow as well as isotope concentration in soil pore water were predicted reasonably well. Due to complex nature of microbial transformations, prediction of DOC rate and transport was associated with a high uncertainty.

  2. Partitioning carbon dioxide emission and assessing dissolved organic carbon leaching of a drained peatland cultivated with pineapple at Saratok, Malaysia.

    PubMed

    Lim Kim Choo, Liza Nuriati; Ahmed, Osumanu Haruna

    2014-01-01

    Pineapples (Ananas comosus (L.) Merr.) cultivation on drained peats could affect the release of carbon dioxide (CO2) into the atmosphere and also the leaching of dissolved organic carbon (DOC). Carbon dioxide emission needs to be partitioned before deciding on whether cultivated peat is net sink or net source of carbon. Partitioning of CO2 emission into root respiration, microbial respiration, and oxidative peat decomposition was achieved using a lysimeter experiment with three treatments: peat soil cultivated with pineapple, bare peat soil, and bare peat soil fumigated with chloroform. Drainage water leached from cultivated peat and bare peat soil was also analyzed for DOC. On a yearly basis, CO2 emissions were higher under bare peat (218.8 t CO2 ha/yr) than under bare peat treated with chloroform (205 t CO2 ha/yr), and they were the lowest (179.6 t CO2 ha/yr) under cultivated peat. Decreasing CO2 emissions under pineapple were attributed to the positive effects of photosynthesis and soil autotrophic activities. An average 235.7 mg/L loss of DOC under bare peat suggests rapid decline of peat organic carbon through heterotrophic respiration and peat decomposition. Soil CO2 emission depended on moderate temperature fluctuations, but it was not affected by soil moisture. PMID:25215335

  3. Partitioning Carbon Dioxide Emission and Assessing Dissolved Organic Carbon Leaching of a Drained Peatland Cultivated with Pineapple at Saratok, Malaysia

    PubMed Central

    Lim Kim Choo, Liza Nuriati; Ahmed, Osumanu Haruna

    2014-01-01

    Pineapples (Ananas comosus (L.) Merr.) cultivation on drained peats could affect the release of carbon dioxide (CO2) into the atmosphere and also the leaching of dissolved organic carbon (DOC). Carbon dioxide emission needs to be partitioned before deciding on whether cultivated peat is net sink or net source of carbon. Partitioning of CO2 emission into root respiration, microbial respiration, and oxidative peat decomposition was achieved using a lysimeter experiment with three treatments: peat soil cultivated with pineapple, bare peat soil, and bare peat soil fumigated with chloroform. Drainage water leached from cultivated peat and bare peat soil was also analyzed for DOC. On a yearly basis, CO2 emissions were higher under bare peat (218.8 t CO2 ha/yr) than under bare peat treated with chloroform (205 t CO2 ha/yr), and they were the lowest (179.6 t CO2 ha/yr) under cultivated peat. Decreasing CO2 emissions under pineapple were attributed to the positive effects of photosynthesis and soil autotrophic activities. An average 235.7 mg/L loss of DOC under bare peat suggests rapid decline of peat organic carbon through heterotrophic respiration and peat decomposition. Soil CO2 emission depended on moderate temperature fluctuations, but it was not affected by soil moisture. PMID:25215335

  4. Removal of organic impurities from liquid carbon dioxide

    NASA Astrophysics Data System (ADS)

    Zito, Richard R.

    2002-09-01

    The use of a high velocity stream of carbon dioxide snowflakes to clean large optics is well known, and has gained widespread acceptance in the astronomical community as a telescope maintenance technique. Ultimately, however, the success of carbon dioxide snow cleaning depends on the availability of high purity carbon dioxide. The higher the purity of the carbon dioxide, the longer will be the time interval between required mirror washings. The highest grades of commercially produced liquid carbon dioxide are often not available in the more remote regions of the world - such as where major astronomical observatories are often located. Furthermore, the purity of even the highest grades of carbon dioxide are only nominal, and wide variations are known to occur from tank to tank. Occasionally, visible deposits of organic impurities are left behind during cleaning with carbon dioxide that is believed to be 99.999% pure. A zeolite molecular sieve based filtration system has proven to be very effective in removing these organic impurities. A zeolite is a complex alumino-silicate. One example has an empirical formula of Na2O(Al2O3)(SiO2)2yH2O, where y=0 to 8. The zeolites have an open crystal structure and are capable of trapping impurities like 8-methylheptadecane (an oil) and 2,6-octadine-1-ol,3,7- dimethyl-,(E)- (a fatty acid). In fact, a zeolite can trap 29.5% of its own weight in SAE 20 lubricant at 25 degree(s)C. After filtration of liquid CO2 through zeolites, the concentration of measured impurities was below the detection limit for state-of-the-art gas chromatography systems.

  5. Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

    SciTech Connect

    Mattigod, Shas V.; Wellman, Dawn M.; Golovich, Elizabeth C.; Cordova, Elsa A.; Smith, Ronald M.

    2010-12-01

    CH2M HILL Plateau Remediation Company (CHPRC) is currently developing a 200-West Area groundwater pump-and-treat system as the remedial action selected under the Comprehensive Environmental Response, Compensation, and Liability Act Record of Decision for Operable Unit (OU) 200-ZP-1. This report documents the results of treatability tests Pacific Northwest National Laboratory researchers conducted to quantify the ability of selected activated carbon products (or carbons) to adsorb technetium-99 (Tc-99) from 200-West Area groundwater. The Tc-99 adsorption performance of seven activated carbons (J177601 Calgon Fitrasorb 400, J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, J177612 Norit GAC830, J177613 Norit GAC830, and J177617 Nucon LW1230) were evaluated using water from well 299-W19-36. Four of the best performing carbons (J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, and J177613 Norit GAC830) were selected for batch isotherm testing. The batch isotherm tests on four of the selected carbons indicated that under lower nitrate concentration conditions (382 mg/L), Kd values ranged from 6,000 to 20,000 mL/g. In comparison. Under higher nitrate (750 mg/L) conditions, there was a measureable decrease in Tc-99 adsorption with Kd values ranging from 3,000 to 7,000 mL/g. The adsorption data fit both the Langmuir and the Freundlich equations. Supplemental tests were conducted using the two carbons that demonstrated the highest adsorption capacity to resolve the issue of the best fit isotherm. These tests indicated that Langmuir isotherms provided the best fit for Tc-99 adsorption under low nitrate concentration conditions. At the design basis concentration of Tc 0.865 µg/L(14,700 pCi/L), the predicted Kd values from using Langmuir isotherm constants were 5,980 mL/g and 6,870 mL/g for for the two carbons. These Kd values did not meet the target Kd value of 9,000 mL/g. Tests

  6. Enhanced capacitive properties of commercial activated carbon by re-activation in molten carbonates

    NASA Astrophysics Data System (ADS)

    Lu, Beihu; Xiao, Zuoan; Zhu, Hua; Xiao, Wei; Wu, Wenlong; Wang, Dihua

    2015-12-01

    Simple, affordable and green methods to improve capacitive properties of commercial activated carbon (AC) are intriguing since ACs possess a predominant role in the commercial supercapacitor market. Herein, we report a green reactivation of commercial ACs by soaking ACs in molten Na2CO3-K2CO3 (equal in mass ratios) at 850 °C combining the merits of both physical and chemical activation strategies. The mechanism of molten carbonate treatment and structure-capacitive activity correlations of the ACs are rationalized. Characterizations show that the molten carbonate treatment increases the electrical conductivity of AC without compromising its porosity and wettability of electrolytes. Electrochemical tests show the treated AC exhibited higher specific capacitance, enhanced high-rate capability and excellent cycle performance, promising its practical application in supercapacitors. The present study confirms that the molten carbonate reactivation is a green and effective method to enhance capacitive properties of ACs.

  7. The Decomposition of Carbonates and Organics on Mars

    NASA Technical Reports Server (NTRS)

    Quinn, Richard C.; Zent, Aaron; McKay, Chris; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The return and analysis of pristine material that is relict of a putative period of chemical evolution is a fumdamental goal of the exobiological exploration of Mars. In order to accomplish this objective, it is desirable to find oxidant-free regions where pristine material can be accessed at the shallowest possible depth (ideally directly from the surface). The objective of our ongoing research is to understand the spatial and temporal distribution of oxidants in the martian regolith and the redox chemistry of the soil; in effect to understand the chemical mechanisms and kinetics relating to the in-situ destruction of organics and the formation of the reactive species responsible for the Viking biology results. In this work, we report on experimental studies of oxidizing processes that may contribute to carbonate and organic degradation on Mars. Organic molecules directly exposed to solar UV may decomposed either directly into CO2, or into more volatile organic fragments. Organic macromolecules not directly exposed to high UV flux are most likely to be affected by atmospheric oxidants which can diffuse to their surfaces. The oxidizing processes examined include: gas-phase oxidants, UV photolysis, and UV-assisted heterogeneous catalysis. For example, assuming a meteroritic infall rate of 4 x 10(exp -4) g/m^2yr (Flynn and McKay 1990) and a flux of organic carbon of 2 x 10(exp -5) g/m^2yr, laboratory measurements of the UV-assisted decomposition of benzenehexacarboxylic acid (mellitic acid, a likely intermediate of kerogen oxidation), indicate its decomposition rate on Mars would exceed the total flux of organic carbon to the planet by over four orders of magnitude. Our measurements indicate that although the decomposition temperature of kerogens in some cases exceeds the temperature limit of the Viking GCMS, it is unlikely kerogens or their decomposition intermediates were present at the Viking landings sites at levels above the GCMS detection limits.

  8. Terrestrial organic carbon contributions to sediments on the Washington margin

    SciTech Connect

    Prahl, F.G.; Sparrow, M.A.; Eversmeyer, B. ); Ertel, J.R. ); Goni, M.A. )

    1994-07-01

    Elemental and stable carbon isotopic compositions and biomarker concentrations were determined in sediments from the Columbia River basin and the Washington margin in order to evaluate geochemical approaches for quantifying terrestrial organic matter in marine sediments. The biomarkers include: an homologous series of long-chain n-alkanes derived from the surface waxes of higher plants; phenolic and hydroxyalkanoic compounds produced by CuO oxidation of two major vascular plant biopolymers, lignin and cutin. All marine sediments, including samples collected from the most remote sites in Cascadia Basin, showed organic geochemical evidence for the presence of terrestrial organic carbon. Using endmember values for the various biomarkers determined empirically by two independent means, the authors estimate that the terrestrial contribution to the Washington margin is [approximately] 60% for shelf sediments, [approximately] 30% for slope sediments, and decreases further to [le] 15% in basin sediments. Results from the same geochemical measurements made with depth in gravity core 6705-7 from Cascadia Seachannel suggest that this approach to assess terrestrial organic carbon contributions to contemporary deposits on the Washington margin can be applied to the study of sediments depositing in this region since the last glacial period.

  9. COMPARISON OF SAMPLING METHODS FOR SEMI-VOLATILE ORGANIC CARBON (SVOC) ASSOCIATED WITH PM 2.5

    EPA Science Inventory

    This study evaluates the influence of denuder sampling methods and filter collection media on the measurement of semi-volatile organic carbon (SVOC) associated with PM2.5. Two types of collection media, charcoal (activated carbon) and XAD, were used both in diffusion denuders ...

  10. Retardation of volatile organic compounds in ground water in low organic carbon sediments

    SciTech Connect

    Hoffman, F.

    1995-04-01

    It is postulated that adsorption onto aquifer matrix surfaces is only one of the processes that retard contaminants in ground water in unconsolidated sediments; others include hydrodynamic dispersion, abiotic/biotic degradation, matrix diffusion, partitioning to organic carbon, diffusion into and retention in dead-end pores, etc. This work aims at these processes in defining the K{sub d} of VOCs in sediments with low organic carbon content. Experiments performed include an initial column experiment for VOC (TCE and perchloroethylene(PCE)) retardation tests on geological materials, PCE and TCE data from LLNL sediments, and a preliminary multilayer sampler experiment. The VOC K{sub d}s in low organic carbon permeable aquifer materials are dependent on the VOC composition and independent of aquifer grain size, indicating that sorption was not operative and that the primary retarding factors are diffusion controlled. The program of future experiments is described.

  11. Kinetics of adsorption with granular, powdered, and fibrous activated carbon

    SciTech Connect

    Shmidt, J.L.; Pimenov, A.V.; Lieberman, A.I.; Cheh, H.Y.

    1997-08-01

    The properties of three different types of activated carbon, fibrous, powdered, and granular, were investigated theoretically and experimentally. The adsorption rate of the activated carbon fiber was found to be two orders of magnitude higher than that of the granular activated carbon, and one order of magnitude higher than that of the powdered activated carbon. Diffusion coefficients of methylene blue in the fibrous, powdered, and granular activated carbons were determined experimentally. A new method for estimating the meso- and macropore surface areas in these carbons was proposed.

  12. METHOD 415.3 - MEASUREMENT OF TOTAL ORGANIC CARBON, DISSOLVED ORGANIC CARBON AND SPECIFIC UV ABSORBANCE AT 254 NM IN SOURCE WATER AND DRINKING WATER

    EPA Science Inventory

    2.0 SUMMARY OF METHOD

    2.1 In both TOC and DOC determinations, organic carbon in the water sample is oxidized to form carbon dioxide (CO2), which is then measured by a detection system. There are two different approaches for the oxidation of organic carbon in water sample...

  13. Litter contribution to soil organic carbon in the agriculture abandons processes

    NASA Astrophysics Data System (ADS)

    Novara, Agata; Francaviglia, Dario; La Mantia, tommaso; Gristina, Luciano; La Bella, Salvatore; Tuttolomondo, Teresa

    2015-04-01

    Mechanisms of litter decomposition, translocation and stabilization into soil layers are fundamental processes in ecosystem functioning as it regulates the cycle of soil organic matter (SOM), CO2 emission into the atmosphere, carbon sequestration into the soil. In this study, it was investigated the contribution of litters of different stages of Mediterranean secondary succession on Carbon sequestration, analyzing the role of earthworms on translocation of SOM into soil profile. For this purpose δ13C difference between meadow C4-C soil and C3-C litter were used in a field experiment. Four undisturbed litters of different stages of succession were collected (45, 70, 100 and 120 since agriculture abandon) and placed on the top of isolated soil cores. The litter contribution to C stock was affected by plant species and increased with the age of the stage of secondary succession. The soil organic carbon after 1 year since litter position increased up to 40% in comparison to no litter treatment in soil with litter of 120 years since abandon. The new carbon derived from C3-litter was decomposed and transferred into soil profile thanks to earthworms and dissolved organic carbon leaching. After 1 years the carbon increase attributed to earthworm activity ranged from 6% to 13% in soil under litter in field abandoned since 120 and 45 years, respectively.

  14. Litter contribution to soil organic carbon in the agriculture abandons processes

    NASA Astrophysics Data System (ADS)

    Novara, A.; Rühl, J.; La Mantia, T.; Gristina, L.; La Bella, S.; Tuttolomondo, T.

    2015-02-01

    Mechanisms of litter decomposition, translocation and stabilization into soil layers are fundamental processes in ecosystem functioning as it regulates the cycle of soil organic matter (SOM), CO2 emission into the atmosphere, carbon sequestration into the soil. In this study, it was investigated the contribution of litters of different stages of Mediterranean secondary succession on Carbon sequestration, analyzing the role of earthworms on translocation of SOM into soil profile. For this purpose δ13C difference between meadow C4-Csoil and C3-Clitter were used in a field experiment. Four undisturbed litters of different stages of succession were collected (45, 70, 100 and 120 since agriculture abandon) and placed on the top of isolated soil cores. The litter contribution to C stock was affected by plant species and increased with the age of the stage of secondary succession. The soil organic carbon after 1 year since litter position increased up to 40% in comparison to no litter treatment in soil with litter of 120 years since abandon. The new carbon derived from C3-litter was decomposed and transferred into soil profile thanks to earthworms and dissolved organic carbon leaching. After 1 years the carbon increase attributed to earthworm activity ranged from 6 to 13% in soil under litter in field abandoned since 120 and 45 years, respectively.

  15. Adsorption of chlorophenols on granular activated carbon

    SciTech Connect

    Yang, M.

    1993-12-31

    Studies were undertaken of the adsorption of chlorinated phenols from aqueous solution on granular activated carbon (Filtrasorb-400, 30 x 40 mesh). Single-component equilibrium adsorption data on the eight compounds in two concentration ranges at pH 7.0 fit the Langmuir equation better than the Freundlich equation. The adsorptive capacities at pH 7.0 increase from pentachlorophenol to trichlorophenols and are fairly constant from trichlorophenols to monochlorophenols. The adsorption process was found to be exothermic for pentachlorophenol and 2,4,6-trichlorophenol, and endothermic for 2,4-dichlorophenol and 4-chlorophenol. Equilibrium measurements were also conducted for 2,4,5-trichlorophenol, 2,4-dichlorophenol, and 4-chlorophenol over a wide pH range. A surface complexation model was proposed to describe the effect of pH on adsorption equilibria of chlorophenols on activated carbon. The simulations of the model are in excellent agreement with the experimental data. Batch kinetics studies were conducted of the adsorption of chlorinated phenols on granular activated carbon. The results show that the surface reaction model best describes both the short-term and long-term kinetics, while the external film diffusion model describes the short-term kinetics data very well and the linear-driving-force approximation improved its performance for the long-term kinetics. Multicomponent adsorption equilibria of chlorophenols on granular activated carbon was investigated in the micromolar equilibrium concentration range. The Langmuir competitive and Ideal Adsorbed Solution (IAS) models were tested for their performance on the three binary systems of pentachlorophenol/2,4,6-trichlorophenol, 2,4,6-trichlorophenol/2,4-dichlorophenol, and 2,4-dichlorophenol/4-chlorophenol, and the tertiary system of 2,4,6-trichlorophenol/2,4-dichlorophenol/4-chlorophenol, and found to fail to predict the two-component adsorption equilibria of the former two binary systems and the tertiary system.

  16. Biogeochemistry of Two Types of Permeable Reafctive Barriers, Organic Carbon and Iron-bearing Organic Carbon for Mine Drainage treatment: Column experiments

    SciTech Connect

    Guo, Q.; Blowes, D

    2009-01-01

    Permeable reactive barriers (PRBs) are an alternative technology to treat mine drainage containing sulfate and heavy metals. Two column experiments were conducted to assess the suitability of an organic carbon (OC) based reactive mixture and an Fe{sup 0}-bearing organic carbon (FeOC) based reactive mixture, under controlled groundwater flow conditions. The organic carbon mixture contains about 30% (volume) organic carbon (composted leaf mulch) and 70% (volume) sand and gravel. The Fe{sup 0}-bearing organic carbon mixture contains 10% (volume) zero-valent iron, 20% (volume) organic carbon, 10% (volume) limestone, and 60% (volume) sand and gravel. Simulated groundwater containing 380 ppm sulfate, 5 ppm As, and 0.5 ppm Sb was passed through the columns at flow rates of 64 (the OC column) and 62 (the FeOC column) ml d{sup -1}, which are equivalent to 0.79 (the OC column) and 0.78 (the FeOC column) pore volumes (PVs) per week or 0.046 m d{sup -1} for both columns. The OC column showed an initial sulfate reduction rate of 0.4 {mu}mol g (OC){sup -1} d{sup -1} and exhausted its capacity to promote sulfate reduction after 30 PVs, or 9 months of flow. The FeOC column sustained a relatively constant sulfate reduction rate of 0.9 {mu}mol g (OC){sup -1} d{sup -1} for at least 65 PVs (17 months). In the FeOC column, the {delta}34S values increase with the decreasing sulfate concentration. The {delta}34S fractionation follows a Rayleigh fractionation model with an enrichment factor of 21.6%. The performance decline of the OC column was caused by the depletion of substrate or electron donor. The cathodic production of H{sub 2} by anaerobic corrosion of Fe probably sustained a higher level of SRB activity in the FeOC column. These results suggest that zero-valent iron can be used to provide an electron donor in sulfate reducing PRBs. A sharp increase in the {delta}13C value of the dissolved inorganic carbon and a decrease in the concentration of HCO{sub 3}{sup -} indicate that

  17. Aqueous mercury adsorption by activated carbons.

    PubMed

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies. PMID:25644627

  18. Human induced impacts on soil organic carbon in southwest Iceland

    NASA Astrophysics Data System (ADS)