Sample records for inorganic carbon uptake

  1. Laboratory investigation of inorganic carbon uptake by cryoconite debris from Werenskioldbreen, Svalbard

    NASA Astrophysics Data System (ADS)

    Stibal, Marek; Tranter, Martyn

    2007-12-01

    Laboratory experiments were undertaken to determine the inorganic carbon uptake rate and the interactions between photosynthesis and water chemistry, particularly pH and nutrient concentrations, for cryoconite debris from Werenskioldbreen, a well-researched Svalbard glacier. Microorganisms in cryoconite debris took up inorganic carbon at rates between 0.6 and 15 μg C L-1 h-1 and fixed it as organic carbon. Cyanobacterial photosynthesis (75-93%) was the main process responsible for inorganic carbon fixation, while heterotrophic uptake (6-15%) only accounted for a minor part. The microbes in cryoconite debris were active shortly after melt and fixed carbon as long as there were favorable conditions. They were not truly psychrophilic: their physiological optimum temperature was higher than is prevalent in cryoconite holes. The pH was also a factor affecting photosynthesis in the cryoconite slurry. The highest dissolved inorganic carbon (DIC) uptake rates per liter of slurry occurred at pH ˜7, and there was a significant correlation between the initial pH and DIC fixation on a per cell basis, showing increasing DIC uptake rates when pH increased from ˜5.5 to 9. Inorganic carbon fixation resulted in an increased pH in solution. However, the microbes were able to photosynthesize in a wide range of pH from ˜4 to ˜10. The average C:N:P molar ratios in solution were ˜350:75:1. Unlike nitrogen, phosphorus concentrations decreased with increasing carbon uptake, and when the rate approached ˜15 μg C L-1 h-1, all available dissolved phosphorus was utilized within 6 h. Hence phosphorus is probably biolimiting in this system.

  2. Effects of Air Contact on Growth, Inorganic Carbon Sources, and Nitrogen Uptake by an Amphibious Freshwater Macrophyte.

    PubMed Central

    Madsen, T. V.; Breinholt, M.

    1995-01-01

    Callitriche cophocarpa Sendtner is a heterophyllous amphibious macrophyte that produces apical rosettes of floating leaves. The importance of air contact for inorganic carbon and N uptake and for growth was investigated. Plants were grown with the floating rosette in contact with air of various humidities (10, 50, and >90% relative humidity) and with the submerged parts in N-free water at 350 [mu]M free CO2 and the roots in sediment with low or high NH3-N content. Humidity greatly affected the transpiration rate, whereas growth rate and N content were unaffected and were comparable to values measured for fully submerged shoots. Air contact had, however, a significant impact on growth when the free CO2 concentration in the water was low. Thus, the growth rate of shoots with air contact was about 3 times faster than the rate of fully submerged shoots when grown at air-equilibrium concentration of dissolved free CO2 in the water (16 [mu]M). This difference decreased with increased dissolved free CO2 concentration in the water, and the two shoot types grew at the same rate when the submerged shoots received >350 [mu]M free CO2. The quantitative importance of the floating rosette for total carbon uptake declined also with decreased ratio of floating rosette to total shoot weight. It is concluded that floating rosettes can enhance the inorganic carbon uptake of Callitriche. In contrast, air contact is of minor importance for nutrient transport. PMID:12228350

  3. Bioinformatic analysis of the distribution of inorganic carbon transporters and prospective targets for bioengineering to increase Ci uptake by cyanobacteria.

    PubMed

    Gaudana, Sandeep B; Zarzycki, Jan; Moparthi, Vamsi K; Kerfeld, Cheryl A

    2015-10-01

    Cyanobacteria have evolved a carbon-concentrating mechanism (CCM) which has enabled them to inhabit diverse environments encompassing a range of inorganic carbon (Ci: [Formula: see text] and CO2) concentrations. Several uptake systems facilitate inorganic carbon accumulation in the cell, which can in turn be fixed by ribulose 1,5-bisphosphate carboxylase/oxygenase. Here we survey the distribution of genes encoding known Ci uptake systems in cyanobacterial genomes and, using a pfam- and gene context-based approach, identify in the marine (alpha) cyanobacteria a heretofore unrecognized number of putative counterparts to the well-known Ci transporters of beta cyanobacteria. In addition, our analysis shows that there is a huge repertoire of transport systems in cyanobacteria of unknown function, many with homology to characterized Ci transporters. These can be viewed as prospective targets for conversion into ancillary Ci transporters through bioengineering. Increasing intracellular Ci concentration coupled with efforts to increase carbon fixation will be beneficial for the downstream conversion of fixed carbon into value-added products including biofuels. In addition to CCM transporter homologs, we also survey the occurrence of rhodopsin homologs in cyanobacteria, including bacteriorhodopsin, a class of retinal-binding, light-activated proton pumps. Because they are light driven and because of the apparent ease of altering their ion selectivity, we use this as an example of re-purposing an endogenous transporter for the augmentation of Ci uptake by cyanobacteria and potentially chloroplasts.

  4. Dissolved inorganic carbon enhanced growth, nutrient uptake, and lipid accumulation in wastewater grown microalgal biofilms.

    PubMed

    Kesaano, Maureen; Gardner, Robert D; Moll, Karen; Lauchnor, Ellen; Gerlach, Robin; Peyton, Brent M; Sims, Ronald C

    2015-03-01

    Microalgal biofilms grown to evaluate potential nutrient removal options for wastewaters and feedstock for biofuels production were studied to determine the influence of bicarbonate amendment on their growth, nutrient uptake capacity, and lipid accumulation after nitrogen starvation. No significant differences in growth rates, nutrient removal, or lipid accumulation were observed in the algal biofilms with or without bicarbonate amendment. The biofilms possibly did not experience carbon-limited conditions because of the large reservoir of dissolved inorganic carbon in the medium. However, an increase in photosynthetic rates was observed in algal biofilms amended with bicarbonate. The influence of bicarbonate on photosynthetic and respiration rates was especially noticeable in biofilms that experienced nitrogen stress. Medium nitrogen depletion was not a suitable stimulant for lipid production in the algal biofilms and as such, focus should be directed toward optimizing growth and biomass productivities to compensate for the low lipid yields and increase nutrient uptake. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Simulating the effects of light intensity and carbonate system composition on particulate organic and inorganic carbon production in Emiliania huxleyi.

    PubMed

    Holtz, Lena-Maria; Wolf-Gladrow, Dieter; Thoms, Silke

    2015-05-07

    Coccolithophores play an important role in the marine carbon cycle. Variations in light intensity and external carbonate system composition alter intracellular carbon fluxes and therewith the production rates of particulate organic and inorganic carbon. Aiming to find a mechanistic explanation for the interrelation between dissolved inorganic carbon fluxes and particulate carbon production rates, we develop a numerical cell model for Emiliania huxleyi, one of the most abundant coccolithophore species. The model consists of four cellular compartments, for each of which the carbonate system is resolved dynamically. The compartments are connected to each other and to the external medium via substrate fluxes across the compartment-confining membranes. By means of the model we are able to explain several pattern observed in particulate organic and inorganic carbon production rates for different strains and under different acclimation conditions. Particulate organic and inorganic carbon production rates for instance decrease at very low external CO2 concentrations. Our model suggests that this effect is caused mainly by reduced HCO3(-) uptake rates, not by CO2 limitation. The often observed decrease in particulate inorganic carbon production rates under Ocean Acidification is explained by a downregulation of cellular HCO3(-) uptake. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  6. Role of habitat and great oxidation event on the occurrence of three multisubunit inorganic carbon-uptake systems in cyanobacteria.

    PubMed

    Tomar, Vandana; Sidhu, Gurpreet Kaur; Nogia, Panchsheela; Mehrotra, Rajesh; Mehrotra, Sandhya

    2016-03-01

    The oxygenase reaction catalyzed by RuBisCO became an issue only after the evolution of the oxygenic photosynthesis in cyanobacteria. Several strategies were developed by autotrophic organisms as an evolutionary response to increase oxygen levels to help RuBisCO maximize its net carboxylation rate. One of the crucial advancements in this context was the development of more efficient inorganic carbon transporters which could help in increasing the influx of inorganic carbon (Ci) at the site of CO₂ fixation.We conducted a survey to find out the genes coding for cyanobacterial Ci transporters in 40 cyanobacterial phyla with respect to transporters present in Gloeobacter violaceous PCC 7421, an early-diverging cyanobacterium. An attempt was also made to correlate the prevalence of the kind of transporter present in the species with its habitat. Basically, two types of cyanobacterial inorganic carbon transporters exist, i.e. bicarbonate transporters and CO₂-uptake systems. The transporters also show variation in context to their structure as some exist as single subunit proteins (BicA and SbtA), while others exist as multisubunit proteins (namely BCT1, NdhI₃ and NdhI₄). The phylogeny and dist ribution of the former have been extensively studied and the present analysis provides an insight into the latter ones. The in silico analysis of the genes under study revealed that their distribution was greatly influenced by the habitat and major environmental changes such as the great oxidation event (GOE) in the course of their evolution.

  7. Organic-inorganic hybrid carbon dots for cell imaging

    NASA Astrophysics Data System (ADS)

    Liu, Huan; Zhang, Hongwen; Li, Jiayu; Tang, Yuying; Cao, Yu; Jiang, Yan

    2018-04-01

    In this paper, nitrogen-doped carbon dots (CDs) had been synthesized directly by one-step ultrasonic treatment under mild conditions. During the functionalization process, Octa-aminopropyl polyhedral oligomeric silsesquioxane hydrochloride salt (OA-POSS) was used as stabilizing and passivation agent, which lead to self-assembling of CDs in aqueous medium solution. OA-POSS was obtained via hydrolytic condensation of γ-aminopropyl triethoxy silane (APTES). The average size of CDs prepared was approximately 3.3 nm with distribution between 2.5 nm and 4.5 nm. The prepared organic-inorganic hybrid carbon dots have several characteristics such as photoluminescence emission wavelength, efficient cellular uptake, and good biocompatibility. The results indicate that OA-POSS can maintain the fluorescence properties of the carbon dots effectively, and reduced cytotoxicity provides the possibility for biomedical applications. More than 89% of the Hela cells were viable when incubated with 2 mg ml‑1 or lesser organic-inorganic hybrid carbon dots. Thus, it provides a potential for multicolor imaging with HeLa cells.

  8. EFFECT OF CARBONIC ANHYDRASE INHIBITORS ON THE INORGANIC CARBON UPTAKE BY PHYTOPLANKTON NATURAL ASSEMBLAGES(1).

    PubMed

    Mercado, Jesús M; Ramírez, Teodoro; Cortés, Dolores; Liger, Esperanza

    2009-02-01

    The role of carbonic anhydrase (CA) in inorganic carbon acquisition (dissolved inorganic carbon, DIC) was examined in Alboran Sea phytoplankton assemblages. The study area was characterized by a relatively high variability in nutrient concentration and in abundance and taxonomic composition of phytoplankton. Therefore, the relationship between environmental variability and capacity for using HCO3 (-) via external CA (eCA) was examined. Acetazolamide (AZ, an inhibitor of eCA) inhibited the primary productivity (PP) in 50% of the samples, with inhibition percentages ranging from 13% to 60%. The AZ effect was more prominent in the samples that exhibited PP >1 mg C · m(-3)  · h(-1) , indicating that the contribution of eCA to the DIC photosynthetic flux was irrelevant at low PP. The inhibition of primary productivity by AZ was significantly correlated to the abundance of diatoms. However, there was no a relationship between AZ effect and CO2 partial pressure (pCO2 ) or nutrient concentration, indicating that the variability in the PP percentage supported by eCA was mainly due to differences in taxonomic composition of the phytoplankton assemblages. Ethoxyzolamide (EZ, an inhibitor of both external and internal CA) affected 13 of 14 analyzed samples, with PP inhibition percentages varying from 50% to 95%. The effects of AZ and EZ were partially reversed by doubling DIC concentration. These results imply that CA activity (external and/or internal) was involved in inorganic carbon acquisition in most the samples. However, EZ effect was not correlated with pCO2 or taxonomic composition of the phytoplankton. © 2009 Phycological Society of America.

  9. Review of progress in soil inorganic carbon research

    NASA Astrophysics Data System (ADS)

    Bai, S. G.; Jiao, Y.; Yang, W. Z.; Gu, P.; Yang, J.; Liu, L. J.

    2017-12-01

    Soil inorganic carbon is one of the main carbon banks in the near-surface environment, and is the main form of soil carbon library in arid and semi-arid regions, which plays an important role in the global carbon cycle. This paper mainly focuses on the inorganic dynamic process of soil inorganic carbon in soil environment in arid and semi-arid regions, and summarized the composition and source of soil inorganic carbon, influence factors and soil carbon sequestration.

  10. Analytical electron microscopy of biogenic and inorganic carbonates

    NASA Technical Reports Server (NTRS)

    Blake, David F.

    1989-01-01

    In the terrestrial sedimentary environment, the mineralogically predominant carbonates are calcite-type minerals (rhombohedral carbonates) and aragonite-type minerals (orthorhombic carbonates). Most common minerals precipitating either inorganically or biogenically are high magnesium calcite and aragonite. High magnesium calcite (with magnesium carbonate substituting for more than 7 mole percent of the calcium carbonate) is stable only at temperatures greater than 700 C or thereabouts, and aragonite is stable only at pressures exceeding several kilobars of confining pressure. Therefore, these carbonates are expected to undergo chemical stabilization in the diagenetic environment to ultimately form stable calcite and dolomite. Because of the strong organic control of carbonate deposition in organisms during biomineralization, the microchemistry and microstructure of invertebrate skeletal material is much different than that present in inorganic carbonate cements. The style of preservation of microstructural features in skeletal material is therefore often quite distinctive when compared to that of inorganic carbonate even though wholesale recrystallization of the sediment has taken place. Microstructural and microchemical comparisons are made between high magnesium calcite echinoderm skeletal material and modern inorganic high magnesium calcite inorganic cements, using analytical electron microscopy and related techniques. Similar comparisons are made between analogous materials which have undergone stabilization in the diagenetic environment. Similar analysis schemes may prove useful in distinguishing between biogenic and inorganic carbonates in returned Martian carbonate samples.

  11. Enrichment of Inorganic Martian Dust Simulant with Carbon Component can Provoke Neurotoxicity

    NASA Astrophysics Data System (ADS)

    Pozdnyakova, Natalia; Pastukhov, Artem; Dudarenko, Marina; Borysov, Arsenii; Krisanova, Natalia; Nazarova, Anastasia; Borisova, Tatiana

    2017-02-01

    Carbon is the most abundant dust-forming element in the interstellar medium. Tremendous amount of meteorites containing plentiful carbon and carbon-enriched dust particles have reached the Earth daily. National Institute of Health panel accumulates evidences that nano-sized air pollution components may have a significant impact on the central nervous system (CNS) in health and disease. During inhalation, nano-/microsized particles are efficiently deposited in nasal, tracheobronchial, and alveolar regions and can be transported to the CNS. Based on above facts, here we present the study, the aims of which were: 1) to upgrade inorganic Martian dust simulant derived from volcanic ash (JSC-1a/JSC, ORBITEC Orbital Technologies Corporation, Madison, Wisconsin) by the addition of carbon components, that is, nanodiamonds and carbon dots; 2) to analyse acute effects of upgraded simulant on key characteristics of synaptic neurotransmission; and 3) to compare above effects with those of inorganic dust and carbon components per se. Acute administration of carbon-containing Martian dust analogues resulted in a significant decrease in transporter-mediated uptake of L-[14C]glutamate (the major excitatory neurotransmitter) and [3H]GABA (the main inhibitory neurotransmitter) by isolated rat brain nerve terminals. The extracellular level of both neurotransmitters increased in the presence of carbon-containing Martian dust analogues. These effects were associated with action of carbon components of upgraded Martian dust simulant, but not with its inorganic constituent. This fact indicates that carbon component of native Martian dust can have deleterious effects on extracellular glutamate and GABA homeostasis in the CNS, and so glutamate- and GABA-ergic neurotransmission disballansing exitation and inhibition.

  12. Carbonate-sensitive phytotransferrin controls high-affinity iron uptake in diatoms

    NASA Astrophysics Data System (ADS)

    McQuaid, Jeffrey B.; Kustka, Adam B.; Oborník, Miroslav; Horák, Aleš; McCrow, John P.; Karas, Bogumil J.; Zheng, Hong; Kindeberg, Theodor; Andersson, Andreas J.; Barbeau, Katherine A.; Allen, Andrew E.

    2018-03-01

    In vast areas of the ocean, the scarcity of iron controls the growth and productivity of phytoplankton. Although most dissolved iron in the marine environment is complexed with organic molecules, picomolar amounts of labile inorganic iron species (labile iron) are maintained within the euphotic zone and serve as an important source of iron for eukaryotic phytoplankton and particularly for diatoms. Genome-enabled studies of labile iron utilization by diatoms have previously revealed novel iron-responsive transcripts, including the ferric iron-concentrating protein ISIP2A, but the mechanism behind the acquisition of picomolar labile iron remains unknown. Here we show that ISIP2A is a phytotransferrin that independently and convergently evolved carbonate ion-coordinated ferric iron binding. Deletion of ISIP2A disrupts high-affinity iron uptake in the diatom Phaeodactylum tricornutum, and uptake is restored by complementation with human transferrin. ISIP2A is internalized by endocytosis, and manipulation of the seawater carbonic acid system reveals a second-order dependence on the concentrations of labile iron and carbonate ions. In P. tricornutum, the synergistic interaction of labile iron and carbonate ions occurs at environmentally relevant concentrations, revealing that carbonate availability co-limits iron uptake. Phytotransferrin sequences have a broad taxonomic distribution and are abundant in marine environmental genomic datasets, suggesting that acidification-driven declines in the concentration of seawater carbonate ions will have a negative effect on this globally important eukaryotic iron acquisition mechanism.

  13. 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.

  14. Determining Inorganic and Organic Carbon.

    PubMed

    Koistinen, Jaana; Sjöblom, Mervi; Spilling, Kristian

    2017-11-21

    Carbon is the element which makes up the major fraction of lipids and carbohydrates, which could be used for making biofuel. It is therefore important to provide enough carbon and also follow the flow into particulate organic carbon and potential loss to dissolved organic forms of carbon. Here we present methods for determining dissolved inorganic carbon, dissolved organic carbon, and particulate organic carbon.

  15. Inorganic phosphate uptake in unicellular eukaryotes.

    PubMed

    Dick, Claudia F; Dos-Santos, André L A; Meyer-Fernandes, José R

    2014-07-01

    Inorganic phosphate (Pi) is an essential nutrient for all organisms. The route of Pi utilization begins with Pi transport across the plasma membrane. Here, we analyzed the gene sequences and compared the biochemical profiles, including kinetic and modulator parameters, of Pi transporters in unicellular eukaryotes. The objective of this review is to evaluate the recent findings regarding Pi uptake mechanisms in microorganisms, such as the fungi Neurospora crassa and Saccharomyces cerevisiae and the parasite protozoans Trypanosoma cruzi, Trypanosoma rangeli, Leishmania infantum and Plasmodium falciparum. Pi uptake is the key step of Pi homeostasis and in the subsequent signaling event in eukaryotic microorganisms. Biochemical and structural studies are important for clarifying mechanisms of Pi homeostasis, as well as Pi sensor and downstream pathways, and raise possibilities for future studies in this field. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Substantial inorganic carbon sink in closed drainage basins globally

    NASA Astrophysics Data System (ADS)

    Li, Yu; Zhang, Chengqi; Wang, Naiang; Han, Qin; Zhang, Xinzhong; Liu, Yuan; Xu, Lingmei; Ye, Wangting

    2017-07-01

    Arid and semi-arid ecosystems are increasingly recognized as important carbon storage sites. In these regions, extensive sequestration of dissolved inorganic carbon can occur in the terminal lakes of endorheic basins--basins that do not drain to external bodies of water. However, the global magnitude of this dissolved inorganic carbon sink is uncertain. Here we present isotopic, radiocarbon, and chemical analyses of groundwater, river water, and sediments from the terminal region of the endorheic Shiyang River drainage basin, in arid northwest China. We estimate that 0.13 Pg of dissolved inorganic carbon was stored in the basin during the mid-Holocene. Pollen-based reconstructions of basin-scale productivity suggest that the mid-Holocene dissolved inorganic carbon sink was two orders of magnitude smaller than terrestrial productivity in the basin. We use estimates of dissolved inorganic carbon storage based on sedimentary data from 11 terminal lakes of endorheic basins around the world as the basis for a global extrapolation of the sequestration of dissolved organic carbon in endorheic basins. We estimate that 0.152 Pg of dissolved inorganic carbon is buried per year today, compared to about 0.211 Pg C yr-1 during the mid-Holocene. We conclude that endorheic basins represent an important carbon sink on the global scale, with a magnitude similar to deep ocean carbon burial.

  17. Strongly coupled inorganic-nano-carbon hybrid materials for energy storage.

    PubMed

    Wang, Hailiang; Dai, Hongjie

    2013-04-07

    The global shift of energy production from fossil fuels to renewable energy sources requires more efficient and reliable electrochemical energy storage devices. In particular, the development of electric or hydrogen powered vehicles calls for much-higher-performance batteries, supercapacitors and fuel cells than are currently available. In this review, we present an approach to synthesize electrochemical energy storage materials to form strongly coupled hybrids (SC-hybrids) of inorganic nanomaterials and novel graphitic nano-carbon materials such as carbon nanotubes and graphene, through nucleation and growth of nanoparticles at the functional groups of oxidized graphitic nano-carbon. We show that the inorganic-nano-carbon hybrid materials represent a new approach to synthesize electrode materials with higher electrochemical performance than traditional counterparts made by simple physical mixtures of electrochemically active inorganic particles and conducting carbon materials. The inorganic-nano-carbon hybrid materials are novel due to possible chemical bonding between inorganic nanoparticles and oxidized carbon, affording enhanced charge transport and increased rate capability of electrochemical materials without sacrificing specific capacity. Nano-carbon with various degrees of oxidation provides a novel substrate for nanoparticle nucleation and growth. The interactions between inorganic precursors and oxidized-carbon substrates provide a degree of control over the morphology, size and structure of the resulting inorganic nanoparticles. This paper reviews the recent development of inorganic-nano-carbon hybrid materials for electrochemical energy storage and conversion, including the preparation and functionalization of graphene sheets and carbon nanotubes to impart oxygen containing groups and defects, and methods of synthesis of nanoparticles of various morphologies on oxidized graphene and carbon nanotubes. We then review the applications of the SC

  18. Laboratory Studies of Water Uptake by Biomass Burning Smoke: Role of Fuel Inorganic Content, Combustion Phase and Aging

    NASA Astrophysics Data System (ADS)

    Dubey, M. K.; Bixler, S. L.; Romonosky, D.; Lam, J.; Carrico, C.; Aiken, A. C.

    2017-12-01

    Biomass burning aerosol emissions have substantially increased with observed warming and drying in the southwestern US. While wildfires are projected to intensify missing knowledge on the aerosols hampers assessments. Observations demonstrate that enhanced light absorption by coated black carbon and brown carbon can offset the cooling effects of organic aerosols in wildfires. However, if mixing processes that enhance this absorption reduce the aerosol lifetime it would lower their atmospheric burden. In order to elucidate mechanisms regulating this tradeoff we performed laboratory studies of smoke from biomass burning. We focus on aerosol optical properties and their hygroscopic response. Fresh emissions from burning 30 fuels under flaming and smoldering conditions were investigated. We measured aerosol absorption, scattering and extinction at multiple wavelengths, water uptake at 85% relative humidity (fRH85%) with a humidity controlled dual nephelometer, and black carbon mass with a SP2. Trace gases and the ionic content of the fuel and smoke were also measured We find that whereas the optical properties of smoke were strongly dictated by the flaming versus smoldering nature of the burn, the observed hygroscopicity was intimately linked to the chemical composition of the fuel. The mean hygroscopicity ranged from nearly hydrophobic (fRH85% = 1) to very hydrophilic (fRH85% = 2.1) values typical of pure deliquescent salts. The k values varied from 0.004 to 0.18 and correlated well with inorganic content. Inorganic fuel content was the key driver of hygroscopicity with combustion phase playing a secondary but important role ( 20%). Flaming combustion promoted hygroscopicity by generating refractory black carbon and ions. Smoldering combustion suppressed hygroscopicity by producing hydrogenated organic species. Wildfire smoke was hydrophobic since the evergreen species with low inorganic content dominated in these fires. We also quantify the mass absorption cross

  19. Carbon uptake in granular basalt is mitigated by added organic carbon.

    NASA Astrophysics Data System (ADS)

    Howard, E. L.; Van Haren, J. L. M.; Dontsova, K.

    2017-12-01

    Soils represent a large, and potentially long-term, storage component of the global carbon budget. Accurate projections of the response of soil respiration -the release of CO2 from soils generated either through root respiration or microbial respiration- to rainfall events remains one of the largest uncertainties in global carbon cycling models. Similarly poorly represented in models is the uptake of CO2 by basalt soils. In an attempt to address these unknowns, we have investigated how the addition of carbon influences the negative CO2 flux observed after wetting basalt. At Biosphere 2 we have constructed a large scale environmentally controlled experiment known as the Landscape Evolution Observatory (LEO). The objective of LEO is to observe the interactions between water, microbes, and climate in the formation of soil and landscapes utilizing granular basalt as a young soil. Previous studies show that water addition to the LEO soil leads to considerable CO2 uptake and that the addition of plants does not alter this response. In this study, we conducted soil incubations to investigate the effect of varying soil carbon content on CO2 fluxes. During incubations we measured CO2 emissions from two types of soil (granular basalt and sand soil) mixed with seven (0, 5, 10, 25, 50, 75, 100%) different proportions of Kalso prairie. The carbon content varied from nearly zero in the basalt to 6.5% in the Kalso Prarie soil. Other parameters that influence soil CO2 fluxes such as pH were taken into account. In conclusion, our experiments confirm that unweathered basalt will consume CO2 when wetted, whereas added carbon will cause a strong pulse of CO2 following water addition. This supports our hypotheses that the carbon content is a large contributor and that maturation of basalt flows will lead to a shift in the carbon dynamics from inorganic to organic dominated. Likewise, these transitions would be expected to be present during soil formation after primary succession and

  20. Expression of genes involved in the uptake of inorganic carbon in the gill of a deep-sea vesicomyid clam harboring intracellular thioautotrophic bacteria.

    PubMed

    Hongo, Yuki; Ikuta, Tetsuro; Takaki, Yoshihiro; Shimamura, Shigeru; Shigenobu, Shuji; Maruyama, Tadashi; Yoshida, Takao

    2016-07-10

    Deep-sea vesicomyid clams, including the genus Phreagena (formerly Calyptogena), harbor thioautotrophic bacterial symbionts in the host symbiosome, which consists of cytoplasmic vacuoles in gill epithelial cells called bacteriocytes. The symbiont requires inorganic carbon (Ci), such as CO2, HCO3(-), and CO3(2-), to synthesize organic compounds, which are utilized by the host clam. The dominant Ci in seawater is HCO3(-), which is impermeable to cell membranes. Within the bacteriocyte, cytoplasmic carbonic anhydrase (CA) from the host, which catalyzes the inter-conversion between CO2 and HCO3(-), has been shown to be abundant and is thought to supply intracellular CO2 to symbionts in the symbiosome. However, the mechanism of Ci uptake by the host gill from seawater is poorly understood. To elucidate the influx pathway of Ci into the bacteriocyte, we isolated the genes related to Ci uptake via the pyrosequencing of cDNA from the gill of Phreagena okutanii, and investigated their expression patterns. Using phylogenetic and amino acid sequence analyses, three solute carrier family 4 (SLC4) bicarbonate transporters (slc4co1, slc4co2, and slc4co4) and two membrane-associated CAs (mcaco1 and mcaco2) were identified as candidate genes for Ci uptake. In an in situ hybridization analysis of gill sections, the expression of mcaco1 and mcaco2 was detected in the bacteriocytes and asymbiotic non-ciliated cells, respectively, and the expression of slc4co1 and slc4co2 was detected in the asymbiotic cells, including the intermediate cells of the inner area and the non-ciliated cells of the external area. Although subcellular localizations of the products of these genes have not been fully elucidated, they may play an important role in the uptake of Ci into the bacteriocytes. These findings will improve our understanding of the Ci transport system in the symbiotic relationships of chemosynthetic bivalves. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. 75 FR 29534 - Inorganic Nitrates-Nitrite, Carbon and Carbon Dioxide, and Sulfur Registration Review; Draft...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-26

    ... ENVIRONMENTAL PROTECTION AGENCY [EPA-HQ-OPP-2010-0434; FRL-8826-6] Inorganic Nitrates-Nitrite... for the registration review of inorganic nitrates - nitrites, carbon and carbon dioxide, and gas... identifies those species for which exposure and effects may occur for all inorganic nitrates- nitrites...

  2. [Exchange Fluxes and Coupling Relationship of Dissolved Inorganic Carbon and Dissolved Organic Carbon Across the Water-Sediment Interface in Lakes].

    PubMed

    Wang, Wei-ying; Lü, Chang-wei; He, Jiang; Zuo, Le; Yan, Dao-hao

    2015-10-01

    In this work, the exchange fluxes and coupling relationship of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) were investigated across the water-sediment interface in Lake Wuliangsuhai and Daihai by employing columnar simulation method. The results showed that the sediments in non-Phragmitescommunis area from Lake Wuliangsuhai functioned as the sources of DIC and DOC for overlying water, whereas the sediments from Lake Daihai as the sinks during the period of summer (90 days). In the experimental period, the average exchange rates of DIC and DOC were 71.07 mmol x (m2 x d)(-1) and 185.09 mmol x (m2 x d)(-1) in non-Phragmitescommunis area from Lake Wuliangsuhai, respectively; while in Lake Daihai, they were 155.75 mmol x (m2 x d)(-1) and -1478.08 mmol x (m2 x d)(-1) in shoal water zone, and -486.53 mmol x (m2 x d)(-1) and -1274.02 mmol x (m2 x d)(-1) in deep water zone, respectively. The coupling effects between DIC and DOC were governed by hydrobios, microbial uptake, abiotic and microbiological degradation in Lake Wuliangsuhai and in shoal water zone of Lake Daihai; while they were closely related to the coprecipitation process of CaCO3 and the fraction distribution of inorganic carbon in sediments in deep water zone of Lake Daihai. In summary, the sink or source functions of sediments could be considered as the results of synthetic action of lake types, offshore distance, geohydrochemistry and the fraction distribution of inorganic carbon.

  3. Review of hydrogen storage in inorganic fullerene-like nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, J.; Wu, F.

    Following the discovery of carbon nanotubes, inorganic fullerene-like nanotubes such as WS2-MoS2, NbS2, TiS2, and BN were reported. Inorganic (non-carbon) nanotubes constitute an important class of nanomaterials with interesting properties and potential applications. As known, efficient hydrogen storage is one key problem in the development of a hydrogen energy system. Hydrogen storage using carbon nanostructures is scientifically interesting and challenging. It thus would be worthwhile to look into hydrogen storage in inorganic nanotubes because the van der Waals gaps between the nanotube layers are potential candidates for hydrogen uptake. Furthermore, the inorganic nanotubes combine two elements, which is different from the pure carbon nanotubes. These may show a novel hydrogen adsorption-desorption mechanism. The present review provides a brief study of hydrogen adsorption on MoS2, TiS2, and BN nanotubes.

  4. Solute-specific scaling of inorganic nitrogen and phosphorus uptake in streams

    NASA Astrophysics Data System (ADS)

    Hall, R. O., Jr.; Baker, M. A.; Rosi-Marshall, E. J.; Tank, J. L.; Newbold, J. D.

    2013-11-01

    Stream ecosystem processes such as nutrient cycling may vary with stream position in the network. Using a scaling approach, we examined the relationship between stream size and nutrient uptake length, which represents the mean distance that a dissolved solute travels prior to removal from the water column. Ammonium (NH4+) uptake length increased proportionally with stream size measured as specific discharge (discharge/stream width) with a scaling exponent = 1.01. In contrast, uptake lengths for nitrate (NO3-) and soluble reactive phosphorus (SRP) increased more rapidly than increases in specific discharge (scaling exponents = 1.19 for NO3- and 1.35 for SRP). Additionally, the ratio of inorganic nitrogen (N) uptake length to SRP uptake length declined with stream size; there was relatively lower demand for SRP compared to N as stream size increased. Finally, we related the scaling of uptake length with specific discharge to that of stream length using Hack's law and downstream hydraulic geometry. Ammonium uptake length increased less than proportionally with distance from the headwaters, suggesting a strong role for larger streams and rivers in regulating nutrient transport.

  5. Nitrogen recovery from wastewater using gas-permeable membranes: Impact of inorganic carbon content and natural organic matter.

    PubMed

    Daguerre-Martini, S; Vanotti, M B; Rodriguez-Pastor, M; Rosal, A; Moral, R

    2018-06-15

    Gas-permeable membranes coupled with low-rate aeration is useful to recover ammonia (NH 4 + ) from livestock effluents. In this study, the role of inorganic carbon (bicarbonate, HCO 3 - ) to enhance the N recovery process was evaluated using synthetic effluents with various NH 4 + to HCO 3 - molar ratios of 0.5, 1.0, 1.5 and 2.0. The study also evaluated the effect of increased organic matter on the NH 4 + recovery using humic acids (3000-6000 mg L -1 ), and the N recovery from high-strength swine manure. The release of hydroxide from the HCO 3 - with aeration increased the wastewater pH and promoted gaseous ammonia formation and membrane uptake. At the same time, the recovery of gaseous ammonia (NH 3 ) through the membrane acidified the wastewater. Therefore, an abundant inorganic carbon supply in balance with the NH 4 + is needed for a successful operation of the technology. NH 4 + removal efficiencies >96% were obtained with NH 4 + to HCO 3 - ratios ≤1. However, higher molar ratios inhibited the N recovery process resulting in lower efficiencies (<65%). Fortunately, most swine manures contain ample supply of endogenous inorganic carbon and the process can be used to more economically recover the ammonia using the natural inorganic carbon instead of expensive alkali chemicals. In 4 days, the recovered NH 4 + from swine manure contained 48,000 mg L -1 . Finally, it was found the process was not inhibited by the increasing levels of organic matter in the wastewater evaluated. Published by Elsevier Ltd.

  6. Inorganic Carbon Source for Photosynthesis in the Seagrass Thalassia hemprichii (Ehrenb.) Aschers.

    PubMed

    Abel, K M

    1984-11-01

    Photosynthetic carbon uptake of the tropical seagrass Thalassia hemprichii (Ehrenb.) Aschers was studied by several methods. Photosynthesis in buffered seawater in media in the range of pH 6 to pH 9 showed an exponentially increasing rate with decreasing pH, thus indicating that free CO(2) was a photosynthetic substrate. However, these experiments were unable to determine whether photosynthesis at alkaline pH also contained some component due to HCO(3) (-) uptake. This aspect was further investigated by studying photosynthetic rates in a number of media of varying pH (7.8-8.61) and total inorganic carbon (0.75-13.17 millimolar). In these media, photosynthetic rate was correlated with free CO(2) concentration and was independent of the HCO(3) (-) concentration in the medium. Short time-course experiments were conducted during equilibration of free CO(2) and HCO(3) (-) after injection of (14)C labeled solution at acid or alkaline pH. High initial photosynthetic rates were observed when acidic solutions (largely free CO(2)) were used but not with alkaline solutions. The concentration of free CO(2) was found to be a limiting factor for photosynthesis in this plant.

  7. Inorganic carbon speciation and fluxes in the Congo River

    NASA Astrophysics Data System (ADS)

    Wang, Zhaohui Aleck; Bienvenu, Dinga Jean; Mann, Paul J.; Hoering, Katherine A.; Poulsen, John R.; Spencer, Robert G. M.; Holmes, Robert M.

    2013-02-01

    Seasonal variations in inorganic carbon chemistry and associated fluxes from the Congo River were investigated at Brazzaville-Kinshasa. Small seasonal variation in dissolved inorganic carbon (DIC) was found in contrast with discharge-correlated changes in pH, total alkalinity (TA), carbonate species, and dissolved organic carbon (DOC). DIC was almost always greater than TA due to the importance of CO2*, the sum of dissolved CO2 and carbonic acid, as a result of low pH. Organic acids in DOC contributed 11-61% of TA and had a strong titration effect on water pH and carbonate speciation. The CO2* and bicarbonate fluxes accounted for ~57% and 43% of the DIC flux, respectively. Congo River surface water released CO2 at a rate of ~109 mol m-2 yr-1. The basin-wide DIC yield was ~8.84 × 104 mol km-2 yr-1. The discharge normalized DIC flux to the ocean amounted to 3.11 × 1011 mol yr-1. The DOC titration effect on the inorganic carbon system may also be important on a global scale for regulating carbon fluxes in rivers.

  8. Bicarbonate uptake by Southern Ocean phytoplankton

    NASA Astrophysics Data System (ADS)

    Cassar, Nicolas; Laws, Edward A.; Bidigare, Robert R.; Popp, Brian N.

    2004-06-01

    Marine phytoplankton have the potential to significantly buffer future increases in atmospheric carbon dioxide levels. However, in order for CO2 fertilization to have an effect on carbon sequestration to the deep ocean, the increase in dissolved CO2 must stimulate primary productivity; that is, marine phototrophs must be CO2 limited [, 1993]. Estimation of the extent of bicarbonate (HCO3-) uptake in the oceans is therefore required to determine whether the anthropogenic carbon sources will enhance carbon flux to the deep ocean. Using short-term 14CO2-disequilibrium experiments during the Southern Ocean Iron Experiment (SOFeX), we show that HCO3- uptake by Southern Ocean phytoplankton is significant. Since the majority of dissolved inorganic carbon (DIC) in the ocean is in the form of bicarbonate, the biological pump may therefore be insensitive to anthropogenic CO2. Approximately half of the DIC uptake observed was attributable to direct HCO3- uptake, the other half being direct CO2 uptake mediated either by passive diffusion or active uptake mechanisms. The increase in growth rates and decrease in CO2 concentration associated with the iron fertilization did not trigger any noticeable changes in the mode of DIC acquisition, indicating that under most environmental conditions the carbon concentrating mechanism (CCM) is constitutive. A low-CO2 treatment induced an increase in uptake of CO2, which we attributed to increased extracellular carbonic anhydrase activity, at the expense of direct HCO3- transport across the plasmalemma. Isotopic disequilibrium experimental results are consistent with Southern Ocean carbon stable isotope fractionation data from this and other studies. Although iron fertilization has been shown to significantly enhance phytoplankton growth and may potentially increase carbon flux to the deep ocean, an important source of the inorganic carbon taken up by phytoplankton in this study was HCO3-, whose concentration is negligibly affected by the

  9. The inorganic carbon distribution in Irish coastal waters

    NASA Astrophysics Data System (ADS)

    McGrath, Triona; Cave, Rachel; McGovern, Evin; Kivimae, Caroline

    2014-05-01

    Despite their relatively small surface area, coastal and shelf waters play a crucial role in the global climate through their influence on major biogeochemical cycles. Due to growing concern about ocean acidification as a result of increasing atmospheric CO2 concentrations, measurements of inorganic carbon parameters (dissolved inorganic carbon (DIC), total alkalinity (TA), pH and pCO2) have been made with increasing regularity over the past two decades. While it is clear that open ocean surface waters are acidifying at a fairly uniform rate ( -0.02 pH units per decade), less is known about changes in coastal waters due to the high complexity and spatial variability in these regions. Large spatial and temporal variability in coastal CO2 parameters is mainly due to nutrient inputs, biological activity, upwelling and riverine inputs of alkalinity and inorganic and organic carbon. The inorganic carbon system in Irish coastal waters is presented here, gathered from 9 surveys around the Irish coastline between 2009 and 2013. There are striking contrasts in the CO2 system between different areas, largely attributed to the bedrock composition of the nearby rivers. Freshwater end-member concentrations of TA, calculated from TA-salinity relationships in outer estuarine and nearshore coastal water, were supported by riverine TA data from the Irish Environmental Protection Agency. A large portion of Ireland is covered with limestone bedrock and as a result, many of the rivers have extremely high TA (>5000μmol/kg) due to the carbonate mineral content of the underlying bedrock. While such high TA has resulted in elevated pH and calcium carbonate saturation states in some coastal waters, (e.g. Galway Bay and Dublin Bay), the high TA in other areas was accompanied by particularly high DIC (e.g. River Shannon on the west coast), resulting in lower pH and aragonite/calcite saturation states and even CO2 degassing in the Shannon estuary. Due to non-limestone lithology in many parts

  10. Macronutrient and carbon supply, uptake and cycling across the Antarctic Peninsula shelf during summer.

    PubMed

    Henley, Sian F; Jones, Elizabeth M; Venables, Hugh J; Meredith, Michael P; Firing, Yvonne L; Dittrich, Ribanna; Heiser, Sabrina; Stefels, Jacqueline; Dougans, Julie

    2018-06-28

    The West Antarctic Peninsula shelf is a region of high seasonal primary production which supports a large and productive food web, where macronutrients and inorganic carbon are sourced primarily from intrusions of warm saline Circumpolar Deep Water. We examined the cross-shelf modification of this water mass during mid-summer 2015 to understand the supply of nutrients and carbon to the productive surface ocean, and their subsequent uptake and cycling. We show that nitrate, phosphate, silicic acid and inorganic carbon are progressively enriched in subsurface waters across the shelf, contrary to cross-shelf reductions in heat, salinity and density. We use nutrient stoichiometric and isotopic approaches to invoke remineralization of organic matter, including nitrification below the euphotic surface layer, and dissolution of biogenic silica in deeper waters and potentially shelf sediment porewaters, as the primary drivers of cross-shelf enrichments. Regenerated nitrate and phosphate account for a significant proportion of the total pools of these nutrients in the upper ocean, with implications for the seasonal carbon sink. Understanding nutrient and carbon dynamics in this region now will inform predictions of future biogeochemical changes in the context of substantial variability and ongoing changes in the physical environment.This article is part of the theme issue 'The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change'. © 2018 The Authors.

  11. Macronutrient and carbon supply, uptake and cycling across the Antarctic Peninsula shelf during summer

    PubMed Central

    Jones, Elizabeth M.; Venables, Hugh J.; Firing, Yvonne L.; Dittrich, Ribanna; Heiser, Sabrina; Dougans, Julie

    2018-01-01

    The West Antarctic Peninsula shelf is a region of high seasonal primary production which supports a large and productive food web, where macronutrients and inorganic carbon are sourced primarily from intrusions of warm saline Circumpolar Deep Water. We examined the cross-shelf modification of this water mass during mid-summer 2015 to understand the supply of nutrients and carbon to the productive surface ocean, and their subsequent uptake and cycling. We show that nitrate, phosphate, silicic acid and inorganic carbon are progressively enriched in subsurface waters across the shelf, contrary to cross-shelf reductions in heat, salinity and density. We use nutrient stoichiometric and isotopic approaches to invoke remineralization of organic matter, including nitrification below the euphotic surface layer, and dissolution of biogenic silica in deeper waters and potentially shelf sediment porewaters, as the primary drivers of cross-shelf enrichments. Regenerated nitrate and phosphate account for a significant proportion of the total pools of these nutrients in the upper ocean, with implications for the seasonal carbon sink. Understanding nutrient and carbon dynamics in this region now will inform predictions of future biogeochemical changes in the context of substantial variability and ongoing changes in the physical environment. This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’. PMID:29760112

  12. Bioengineering aspects of inorganic carbon supply to mass algal cultures. Final report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Goldman, J.C.

    1980-06-01

    The work included in this report is part of an ongoing study (currently funded by the Solar Energy Research Institute - Subcontract No. XR-9-8144-1) on the inorganic carbon requirements of microalgae under mass culture conditions and covers the period June 1, 1978 through May 31, 1979. It is divided into two parts appended herein. The first part is a literature review on the inorganic carbon chemical system in relation to algal growth requirements, and the second part deals with the kinetics of inorganic carbon-limited growth of two freshwater chlorophytes including the effect of carbon limitation on cellular chemical composition. Additionalmore » experiment research covered under this contract was reported in the Proceedings of the 3rd Annual Biomass Energy Systems Conferences, pp. 25-32, Bioengineering aspects of inorganic carbon supply to mass algal cultures. Report No. SERI/TP-33-285.« less

  13. 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

  14. 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

  15. In situ spectrophotometric measurement of dissolved inorganic carbon in seawater

    USGS Publications Warehouse

    Liua, Xuewu; Byrne, Robert H.; Adornato, Lori; Yates, Kimberly K.; Kaltenbacher, Eric; Ding, Xiaoling; Yang, Bo

    2013-01-01

    Autonomous in situ sensors are needed to document the effects of today’s rapid ocean uptake of atmospheric carbon dioxide (e.g., ocean acidification). General environmental conditions (e.g., biofouling, turbidity) and carbon-specific conditions (e.g., wide diel variations) present significant challenges to acquiring long-term measurements of dissolved inorganic carbon (DIC) with satisfactory accuracy and resolution. SEAS-DIC is a new in situ instrument designed to provide calibrated, high-frequency, long-term measurements of DIC in marine and fresh waters. Sample water is first acidified to convert all DIC to carbon dioxide (CO2). The sample and a known reagent solution are then equilibrated across a gas-permeable membrane. Spectrophotometric measurement of reagent pH can thereby determine the sample DIC over a wide dynamic range, with inherent calibration provided by the pH indicator’s molecular characteristics. Field trials indicate that SEAS-DIC performs well in biofouling and turbid waters, with a DIC accuracy and precision of ∼2 μmol kg–1 and a measurement rate of approximately once per minute. The acidic reagent protects the sensor cell from biofouling, and the gas-permeable membrane excludes particulates from the optical path. This instrument, the first spectrophotometric system capable of automated in situ DIC measurements, positions DIC to become a key parameter for in situ CO2-system characterizations.

  16. In situ spectrophotometric measurement of dissolved inorganic carbon in seawater.

    PubMed

    Liu, Xuewu; Byrne, Robert H; Adornato, Lori; Yates, Kimberly K; Kaltenbacher, Eric; Ding, Xiaoling; Yang, Bo

    2013-10-01

    Autonomous in situ sensors are needed to document the effects of today's rapid ocean uptake of atmospheric carbon dioxide (e.g., ocean acidification). General environmental conditions (e.g., biofouling, turbidity) and carbon-specific conditions (e.g., wide diel variations) present significant challenges to acquiring long-term measurements of dissolved inorganic carbon (DIC) with satisfactory accuracy and resolution. SEAS-DIC is a new in situ instrument designed to provide calibrated, high-frequency, long-term measurements of DIC in marine and fresh waters. Sample water is first acidified to convert all DIC to carbon dioxide (CO2). The sample and a known reagent solution are then equilibrated across a gas-permeable membrane. Spectrophotometric measurement of reagent pH can thereby determine the sample DIC over a wide dynamic range, with inherent calibration provided by the pH indicator's molecular characteristics. Field trials indicate that SEAS-DIC performs well in biofouling and turbid waters, with a DIC accuracy and precision of ∼2 μmol kg(-1) and a measurement rate of approximately once per minute. The acidic reagent protects the sensor cell from biofouling, and the gas-permeable membrane excludes particulates from the optical path. This instrument, the first spectrophotometric system capable of automated in situ DIC measurements, positions DIC to become a key parameter for in situ CO2-system characterizations.

  17. Uptake of inorganic mercury by human locus ceruleus and corticomotor neurons: implications for amyotrophic lateral sclerosis

    PubMed Central

    2013-01-01

    Background Environmental toxins are suspected to play a role in the pathogenesis of amyotrophic lateral sclerosis (ALS). In an attempt to determine which pathways these toxins can use to enter motor neurons we compared the distribution of mercury in the CNS of a human and of mice that had been exposed to inorganic mercury. Results In the human who had been exposed to metallic mercury, mercury was seen predominantly in the locus ceruleus and corticomotor neurons, as well as in scattered glial cells. In mice that had been exposed to mercury vapor or mercuric chloride, mercury was present in lower motor neurons in the spinal cord and brain stem. Conclusions In humans, inorganic mercury can be taken up predominantly by corticomotor neurons, possibly when the locus ceruleus is upregulated by stress. This toxin uptake into corticomotor neurons is in accord with the hypothesis that ALS originates in these upper motor neurons. In mice, inorganic mercury is taken up predominantly by lower motor neurons. The routes toxins use to enter motor neurons depends on the nature of the toxin, the duration of exposure, and possibly the amount of stress (for upper motor neuron uptake) and exercise (for lower motor neuron uptake) at the time of toxin exposure. PMID:24252585

  18. The leaching of inorganic species from activated carbons produced from waste tyre rubber.

    PubMed

    San Miguel, G; Fowler, G D; Sollars, C J

    2002-04-01

    Waste tyre rubber can be used as a precursor for the production of high quality activated carbons. However, there is concern that inorganic impurities present in the rubber feed may restrict their use in liquid phase applications with high purity requirements. This paper presents an investigation of the presence and the leaching of inorganic species from activated carbons derived from waste tyre rubber. For the purpose of this work, a number of carbons were produced, characterised for their BET surface area and analysed for their inorganic composition. Subsequently, a number of tests were performed to evaluate the leaching of different inorganic species into solution at various pH values and carbon doses. Results showed that rubber-derived carbons contained elevated concentrations of sulphur and zinc, as well as traces of other metals such as lead, cadmium, chromium and molybdenum. Inorganic levels were significantly affected by production conditions, particularly degree of carbon activation and the nature of the gasification agent. However, leaching tests showed that the availability of these species in neutral pH conditions was very limited. Results demonstrated that, when using carbons doses comparable to those employed in water treatment works, only sulphur levels exceeded, in some occasions, health based quality standards proposed for drinking water.

  19. Uptake of dissolved inorganic and organic nitrogen by the benthic toxic dinoflagellate Ostreopsis cf. ovata.

    PubMed

    Jauzein, Cécile; Couet, Douglas; Blasco, Thierry; Lemée, Rodolphe

    2017-05-01

    Environmental factors that shape dynamics of benthic toxic blooms are largely unknown. In particular, for the toxic dinoflagellate Ostreopsis cf. ovata, the importance of the availability of nutrients and the contribution of the inorganic and organic pools to growth need to be quantified in marine coastal environments. The present study aimed at characterizing N-uptake of dissolved inorganic and organic sources by O. cf. ovata cells, using the 15 N-labelling technique. Experiments were conducted taking into account potential interactions between nutrient uptake systems as well as variations with the diel cycle. Uptake abilities of O. cf. ovata were parameterized for ammonium (NH 4 + ), nitrate (NO 3 - ) and N-urea, from the estimation of kinetic and inhibition parameters. In the range of 0 to 10μmolNL -1 , kinetic curves showed a clear preference pattern following the ranking NH 4 + >NO 3 - >N-urea, where the preferential uptake of NH 4 + relative to NO 3 - was accentuated by an inhibitory effect of NH 4 + concentration on NO 3 - uptake capabilities. Conversely, under high nutrient concentrations, the preference for NH 4 + relative to NO 3 - was largely reduced, probably because of the existence of a low-affinity high capacity inducible NO 3 - uptake system. Ability to take up nutrients in darkness could not be defined as a competitive advantage for O. cf. ovata. Species competitiveness can also be defined from nutrient uptake kinetic parameters. A strong affinity for NH 4 + was observed for O. cf. ovata cells that may partly explain the success of this toxic species during the summer season in the Bay of Villefranche-sur-mer (France). Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Uptake and withdrawal of droplets from carbon nanotubes.

    PubMed

    Schebarchov, D; Hendy, S C

    2011-01-01

    We give an account of recent studies of droplet uptake and withdrawal from carbon nanotubes using simple theoretical arguments and molecular dynamics simulations. Firstly, the thermodynamics of droplet uptake and release is considered and tested via simulation. We show that the Laplace pressure acting on a droplet assists capillary uptake, allowing sufficiently small non-wetting droplets to be absorbed. We then demonstrate how the uptake and release of droplets of non-wetting fluids can be exploited for the use of carbon nanotubes as nanopipettes. Finally, we extend the Lucas-Washburn model to deal with the dynamics of droplet capillary uptake, and again test this by comparison with molecular dynamics simulations.

  1. Uptake and withdrawal of droplets from carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Schebarchov, D.; Hendy, S. C.

    2011-01-01

    We give an account of recent studies of droplet uptake and withdrawal from carbon nanotubes using simple theoretical arguments and molecular dynamics simulations. Firstly, the thermodynamics of droplet uptake and release is considered and tested via simulation. We show that the Laplace pressure acting on a droplet assists capillary uptake, allowing sufficiently small non-wetting droplets to be absorbed. We then demonstrate how the uptake and release of droplets of non-wetting fluids can be exploited for the use of carbon nanotubes as nanopipettes. Finally, we extend the Lucas-Washburn model to deal with the dynamics of droplet capillary uptake, and again test this by comparison with molecular dynamics simulations.

  2. Anthropogenic impacts on carbon uptake variability in the subtropical North Atlantic: 1992-2010

    NASA Astrophysics Data System (ADS)

    Tudino, Tobia; Messias, Marie-Jose; Mills, Benjamin J. W.; Watson, Andrew J.; Halloran, Paul R.; Bernardello, Raffaele; Torres-Valdés, Sinhue; Schuster, Ute; Williams, Richard G.; Wanninkhof, Rik

    2017-04-01

    Since 1860, anthropogenic emissions have increased atmospheric CO2 by more than 120ppm. The global ocean has lessened the accompanying climate impacts, taking up 33% of the emitted CO2, with the highest storage per unit area occurring in the North Atlantic. To investigate carbon uptake and storage in the subtropical North Atlantic, we compare three estimates of anthropogenic CO2 (Cant) with dissolved inorganic carbon (DIC) observations. We use data from a repeat (1992-2010) subtropical transect, where we find an average DIC increase of 1.06 μmol/(kg yr). We separate the observed DIC into five components: preindustrial, dissolved hard-tissue, regenerated soft-tissue, Cant, and surface air-sea disequilibrium. Among them, Cant increases approximately linearly over time (0.39-0.62 μmol/(kg yr), depending on the method adopted), contributing to the total DIC rise. Simultaneously, we observe a biologically driven increase (0.38 μmol/(kg yr)) in carbon from regenerated soft-tissue. We link this variation to the possible ongoing Atlantic meridional overturning circulation slow-down (2009-2010) and the associated strengthening of the biological pump. We expand our analysis by assessing outputs from an Earth system model between 1860 and 2100. In the preindustrial control (i.e. with no influence of anthropogenic CO2), we found a predominance of the biological pump in overall carbon uptake, while the industrial simulation leads to a comparable influence of the biological and physical pumps. We conclude that anthropogenic perturbation of the natural long-term variability in oceanic ventilation could affect the remineralized pool of carbon in the subtropical North Atlantic, potentially making it a higher sink for carbon than previously thought.

  3. Epitaxial Relationships between Calcium Carbonate and Inorganic Substrates

    PubMed Central

    Yang, Taewook; Jho, Jae Young; Kim, Il Won

    2014-01-01

    The polymorph-selective crystallization of calcium carbonate has been studied in terms of epitaxial relationship between the inorganic substrates and the aragonite/calcite polymorphs with implication in bioinspired mineralization. EpiCalc software was employed to assess the previously published experimental results on two different groups of inorganic substrates: aragonitic carbonate crystals (SrCO3, PbCO3, and BaCO3) and a hexagonal crystal family (α-Al2O3, α-SiO2, and LiNbO3). The maximum size of the overlayer (aragonite or calcite) was calculated for each substrate based on a threshold value of the dimensionless potential to estimate the relative nucleation preference of the polymorphs of calcium carbonate. The results were in good agreement with previous experimental observations, although stereochemical effects between the overlayer and substrate should be separately considered when existed. In assessing the polymorph-selective nucleation, the current method appeared to provide a better tool than the oversimplified mismatch parameters without invoking time-consuming molecular simulation\\. PMID:25226539

  4. Incorporation of inorganic carbon by Antarctic cryptoendolithic fungi

    NASA Technical Reports Server (NTRS)

    Palmer, R. J. Jr; Friedmann, E. I.

    1988-01-01

    Fungi isolated from the cryptoendolithic community of the Ross Desert are capable of fixing inorganic carbon. Results suggest that lichen mycobionts and parasymbionts are adapted to different water regimes in the cryptoendolithic environment.

  5. The effects of combined application of inorganic Martian dust simulant and carbon dots on glutamate transport rat brain nerve terminals

    NASA Astrophysics Data System (ADS)

    Borisova, Tatiana; Krisanova, Natalia; Nazarova, Anastasiya; Borysov, Arseniy; Pastukhov, Artem; Pozdnyakova, Natalia; Dudarenko, Marina

    2016-07-01

    During inhalation, nano-/microsized particles are efficiently deposited in nasal, tracheobronchial, and alveolar regions and can be transported to the central nervous system (Oberdorster et al., 2004). Recently, the research team of this study found the minor fractions of nanoparticles with the size ~ 50 -60 nm in Lunar and Martian dust stimulants (JSC-1a and JSC, ORBITEC Orbital Technologies Corporation, Madison, Wisconsin), whereas the average size of the simulants was 1 mm and 4mm, respectively (Krisanova et al., 2013). Also, the research team of this study discovered new phenomenon - the neuromodulating and neurotoxic effect of carbon nano-sized particles - Carbon dots (C-dots), originated from ash of burned carbon-containing product (Borisova et al, 2015). The aims of this study was to analyse acute effects of upgraded stimulant of inorganic Martian dust derived from volcanic ash (JSC-1a/JSC, ORBITEC Orbital Technologies Corporation, Madison, Wisconsin) by the addition of carbon components, that is, carbon dots, on the key characteristic of synaptic neurotransmission. Acute administration of carbon-containing Martian dust analogue resulted in a significant decrease in transporter-mediated uptake of L-[14C]glutamate (the major excitatory neurotransmitter) by isolated rat brain nerve terminals. The ambient level of the neurotransmitter in the preparation of nerve terminals increased in the presence of carbon dot-contained Martian dust analogue. These effects were associated with action of carbon component of the upgraded Martian dust stimulant but not with its inorganic constituent.

  6. Radioisotope tracer studies of inorganic carbon and Ca in microbially derived CaCO3

    USGS Publications Warehouse

    Yates, Kimberly K.; Robbins, Lisa L.

    1999-01-01

    Microbial calcification significantly impacts the cycling and deposition of inorganic carbon. This research employs 45Ca and 14C techniques as radioisotopic tracers to examine the role of cellular cycling of Ca2+ and inorganic carbon in CaCO3 precipitation by the unicellular green alga Nannochloris atomus. Implications of the effects of these physiological aspects on CaCO3 precipitation and the effects of microbial calcification on CaCO3 δ13C ratios are discussed. Results from pulse/chase experiments indicate that intracellular Ca2+ is incorporated into extracellular CaCO3. Intracellular inorganic carbon leaks from cells within 10 to 12 s after injection of unlabelled NaHCO3, providing a source of inorganic carbon for extracellular CaCO3. Cellular expulsion of calcium plays a key role in increasing the CaCO3 saturation state at the site of calcification. The δ13C ratios of microbial carbonates may vary depending on the amount of photorespiratory CO2 incorporated.

  7. Inorganic carbon availability in benthic diatom communities: photosynthesis and migration.

    PubMed

    Marques da Silva, Jorge; Cruz, Sónia; Cartaxana, Paulo

    2017-09-05

    Diatom-dominated microphytobenthos (MPB) is the main primary producer of many intertidal and shallow subtidal environments, being therefore of critical importance to estuarine and coastal food webs. Owing to tidal cycles, intertidal MPB diatoms are subjected to environmental conditions far more variable than the ones experienced by pelagic diatoms (e.g. light, temperature, salinity, desiccation and nutrient availability). Nevertheless, benthic diatoms evolved adaptation mechanisms to these harsh conditions, including the capacity to move within steep physical and chemical gradients, allowing them to perform photosynthesis efficiently. In this contribution, we will review present knowledge on the effects of dissolved inorganic carbon (DIC) availability on photosynthesis and productivity of diatom-dominated MPB. We present evidence of carbon limitation of photosynthesis in benthic diatom mats and highly productive MPB natural communities. Furthermore, we hypothesize that active vertical migration of epipelic motile diatoms could overcome local depletion of DIC in the photic layer, providing the cells alternately with light and inorganic carbon supply. The few available longer-term experiments on the effects of inorganic carbon enrichment on the productivity of diatom-dominated MPB have yielded inconsistent results. Therefore, further studies are needed to properly assess the response of MPB communities to increased CO 2 and ocean acidification related to climate change.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Author(s).

  8. New insights into iron acquisition by cyanobacteria: an essential role for ExbB-ExbD complex in inorganic iron uptake

    PubMed Central

    Jiang, Hai-Bo; Lou, Wen-Jing; Ke, Wen-Ting; Song, Wei-Yu; Price, Neil M; Qiu, Bao-Sheng

    2015-01-01

    Cyanobacteria are globally important primary producers that have an exceptionally large iron requirement for photosynthesis. In many aquatic ecosystems, the levels of dissolved iron are so low and some of the chemical species so unreactive that growth of cyanobacteria is impaired. Pathways of iron uptake through cyanobacterial membranes are now being elucidated, but the molecular details are still largely unknown. Here we report that the non-siderophore-producing cyanobacterium Synechocystis sp. PCC 6803 contains three exbB-exbD gene clusters that are obligatorily required for growth and are involved in iron acquisition. The three exbB-exbDs are redundant, but single and double mutants have reduced rates of iron uptake compared with wild-type cells, and the triple mutant appeared to be lethal. Short-term measurements in chemically well-defined medium show that iron uptake by Synechocystis depends on inorganic iron (Fe′) concentration and ExbB-ExbD complexes are essentially required for the Fe′ transport process. Although transport of iron bound to a model siderophore, ferrioxamine B, is also reduced in the exbB-exbD mutants, the rate of uptake at similar total [Fe] is about 800-fold slower than Fe′, suggesting that hydroxamate siderophore iron uptake may be less ecologically relevant than free iron. These results provide the first evidence that ExbB-ExbD is involved in inorganic iron uptake and is an essential part of the iron acquisition pathway in cyanobacteria. The involvement of an ExbB-ExbD system for inorganic iron uptake may allow cyanobacteria to more tightly maintain iron homeostasis, particularly in variable environments where iron concentrations range from limiting to sufficient. PMID:25012898

  9. Enhancement of inorganic Martian dust simulant with carbon component and its effects on key characteristics of glutamatergic neurotransmission

    NASA Astrophysics Data System (ADS)

    Borisova, Tatiana; Krisanova, Natalia; Nazarova, Anastasiya; Borysov, Arseniy; Pastukhov, Artem; Pozdnyakova, Natalia; Dudarenko, Marina

    2016-07-01

    Evidence on the past existence of subsurface organic-bearing fluids on Mars was recently achieved basing on the investigation of organic carbon from the Tissint Martian meteorite (Lin et al., 2014). Tremendous amount of meteorites containing abundant carbon and carbon-enriched dust particles have reached the Earth daily (Pizzarello and Shock 2010). National Institute of Environmental Health Sciences/National Institute of Health panel of research scientists revealed recently that accumulating evidences suggest that nano-sized air pollution may have a significant impact on central nervous system in health and disease (Block et al., Neurotoxicology, 2012). During inhalation, nano-/microsized particles are efficiently deposited in nasal, tracheobronchial, and alveolar regions and can be transported to the central nervous system (Oberdorster et al., 2004). Based on above facts, the aims of this study were: 1) to upgrade inorganic Martian dust stimulant derived from volcanic ash (JSC-1a/JSC, ORBITEC Orbital Technologies Corporation, Madison, Wisconsin) by the addition of carbon components, that is, nanodiamonds; 2) to analyse acute effects of upgraded stimulant on the key characteristic of synaptic neurotransmission and to compare its effects with those of inorganic dust and carbon components per se. Acute administration of carbon-containing Martian dust analogue resulted in a significant decrease in Na+-dependent uptake of L-[14C]glutamate that is the major excitatory neurotransmitter in the central nervous system (CNS). The ambient level of the neurotransmitter in the preparation of isolated rat brain nerve terminals increased in the presence of carbon-contained Martian dust analogue. This fact indicated that carbon component of native Martian dust can have deleterious effects on extracellular glutamate homeostasis in the CNS, and so glutamatergic neurtransmission.

  10. Isopycnal mixing by mesoscale eddies significantly impacts oceanic anthropogenic carbon uptake

    NASA Astrophysics Data System (ADS)

    Gnanadesikan, Anand; Pradal, Marie-Aude; Abernathey, Ryan

    2015-06-01

    Anthropogenic carbon dioxide uptake varies across Earth System Models for reasons that have remained obscure. When varied within a single model, the lateral eddy mixing coefficient ARedi produces a range of uptake similar to the modeled range. The highest uptake, resulting from a simulation with a constant ARedi of 2400 m2/s, simulates 15% more historical carbon uptake than a model with ARedi = 400 m2/s. A sudden doubling in carbon dioxide produces a 21% range in carbon uptake across the models. Two spatially dependent representations of ARedi produce uptake that lies in the middle of the range of constant values despite predicting very large values in the subtropical gyres. One-dimensional diffusive models of the type used for integrated assessments can be fit to the simulations, with ARedi accounting for a substantial fraction of the effective vertical diffusion. Such models, however, mask significant regional changes in stratification and biological carbon storage.

  11. Fractionation between inorganic and organic carbon during the Lomagundi (2.22 2.1 Ga) carbon isotope excursion

    NASA Astrophysics Data System (ADS)

    Bekker, A.; Holmden, C.; Beukes, N. J.; Kenig, F.; Eglinton, B.; Patterson, W. P.

    2008-07-01

    The Lomagundi (2.22-2.1 Ga) positive carbon isotope excursion in shallow-marine sedimentary carbonates has been associated with the rise in atmospheric oxygen, but subsequent studies have demonstrated that the carbon isotope excursion was preceded by the rise in atmospheric oxygen. The amount of oxygen released to the exosphere during the Lomagundi excursion is constrained by the average global fractionation between inorganic and organic carbon, which is poorly characterized. Because dissolved inorganic and organic carbon reservoirs were arguably larger in the Paleoproterozoic ocean, at a time of lower solar luminosity and lower ocean redox state, decoupling between these two variables might be expected. We determined carbon isotope values of carbonate and organic matter in carbonates and shales of the Silverton Formation, South Africa and in the correlative Sengoma Argillite Formation, near the border in Botswana. These units were deposited between 2.22 and 2.06 Ga along the margin of the Kaapvaal Craton in an open-marine deltaic setting and experienced lower greenschist facies metamorphism. The prodelta to offshore marine shales are overlain by a subtidal carbonate sequence. Carbonates exhibit elevated 13C values ranging from 8.3 to 11.2‰ vs. VPDB consistent with deposition during the Lomagundi positive excursion. The total organic carbon (TOC) contents range from 0.01 to 0.6% and δ13C values range from - 24.8 to - 13.9‰. Thus, the isotopic fractionation between organic and carbonate carbon was on average 30.3 ± 2.8‰ ( n = 32) in the shallow-marine environment. The underlying Sengoma shales have highly variable TOC contents (0.14 to 21.94%) and δ13C values (- 33.7 to - 20.8‰) with an average of - 27.0 ± 3.0‰ ( n = 50). Considering that the shales were also deposited during the Lomagundi excursion, and taking δ13C values of the overlying carbonates as representative of the δ13C value of dissolved inorganic carbon during shale deposition, a carbon

  12. Lateral Flow of Carbon From U.S. Agricultural Lands: Carbon Uptake, Consumption, and Respiration

    NASA Astrophysics Data System (ADS)

    Sabesan, A.; West, T. O.; Roddy, A. B.; Marland, G.; Bhaduri, B. L.

    2005-12-01

    Net carbon exchange between biomass and the atmosphere can be estimated and modeled on a regional basis to understand the effects of land-use change on the carbon cycle and on net CO2 emissions to the atmosphere. However, within ecosystems that are managed to produce commodities for consumption (i.e., agriculture and forest lands), carbon can be transported laterally when crops or timber are harvested, in addition to being transported vertically between plants and the atmosphere. The spatial and temporal domain over which carbon uptake, transport, and release occur has implications for regional carbon studies. For example, carbon may be taken up by crops in one region, but released through human consumption in another region. Estimates of lateral transport and release of carbon may therefore contribute another dimension to bottom-up carbon modeling, and may also be used as input for comparison to top-down atmospheric modeling. Our research to date has focused on the uptake, consumption, and respiration of CO2 associated with agricultural crops and related food commodities. We estimate a net uptake of 495 Tg C on U.S. croplands in 2000. This uptake occurs primarily in the Midwestern U.S. Human respiration of CO2 contributed about 31 Tg C and livestock emitted about 77 Tg C as CO2 and CH4 in 2000. Estimates of CO2 from food wastes in municipal landfills and from human excrement in wastewater treatment plants are currently being developed. The spatial distribution of CO2 uptake and release are mapped, respectively, at the county level and at 1km resolution that is commensurate with Landscan USA population data.

  13. Carbon balance in an irrigated corn field after inorganic fertilizer or manure application

    USDA-ARS?s Scientific Manuscript database

    Little is known about inorganic fertilizer or manure effects on organic carbon (OC) and inorganic C (IC) losses from a furrow irrigated field, particularly in the context of other system C gains or losses. In 2003 and 2004, we measured dissolved organic and inorganic C (DOC, DIC), particulate OC an...

  14. Manure and inorganic fertilizer effects on carbon balance and losses in irrigated corn

    USDA-ARS?s Scientific Manuscript database

    Little is known about inorganic fertilizer or manure effects on organic carbon (OC) and inorganic C (IC) losses from a furrow irrigated field, particularly in the context of other system C gains or losses. In 2003 and 2004, we measured dissolved organic and inorganic C (DOC, DIC), particulate OC an...

  15. Dissolved organic carbon biodegradability from thawing permafrost stimulated by sunlight rather than inorganic nitrogen

    NASA Astrophysics Data System (ADS)

    Liu, F.; Chen, L.; Zhang, B.; Wang, G.; Qin, S.; Yang, Y.

    2017-12-01

    Permafrost thaw could result in a large portion of frozen carbon being laterally transferred to aquatic ecosystems as dissolved organic carbon (DOC). During this delivery process, the size of biodegradable DOC (BDOC) determines the proportion of DOC mineralized by microorganisms and associated carbon loss to the atmosphere, which may further trigger positive carbon-climate feedback. Thermokarst is an abrupt permafrost thaw process that can enhance DOC export and also impact DOC processing through increased inorganic nitrogen (N) and sunlight exposure. However, it remains unclear how thermokarst-impacted BDOC responds to inorganic N addition and ultraviolet (UV) light irradiation. Here we explored the responses of DOC concentration, composition and its biodegradability to inorganic N and UV light in a typical thermokarst on the Tibetan Plateau, by combining field observation and laboratory incubation with spectra analyses (UV-visible absorption and three-dimensional fluorescence spectra) and parallel factor analyses. Our results showed that BDOC in thermokarst feature outflows was significantly higher than in reference water. Furthermore, inorganic N addition had no influence on thermokarst-impacted BDOC, whereas exposure to UV light significantly increased BDOC by as much as 2.3 times higher than the dark-control. Moreover, N addition and UV irradiation did not generate additive effects on BDOC. These results imply that sunlight rather than inorganic N can increase thermokarst-derived BDOC, potentially strengthening the positive permafrost carbon-climate feedback.

  16. A simple, gravimetric method to quantify inorganic carbon in calcareous soils

    USDA-ARS?s Scientific Manuscript database

    Total carbon (TC) in calcareous soils has two components: inorganic carbon (IC) as calcite and or dolomite and organic carbon (OC) in the soil organic matter. The IC must be measured and subtracted from TC to obtain OC. Our objective was to develop a simple gravimetric technique to quantify IC. Th...

  17. Storage/Turnover Rate of Inorganic Carbon and Its Dissolvable Part in the Profile of Saline/Alkaline Soils

    PubMed Central

    Wang, Yugang; Wang, Zhongyuan; Li, Yan

    2013-01-01

    Soil inorganic carbon is the most common form of carbon in arid and semiarid regions, and has a very long turnover time. However, little is known about dissolved inorganic carbon storage and its turnover time in these soils. With 81 soil samples taken from 6 profiles in the southern Gurbantongute Desert, China, we investigated the soil inorganic carbon (SIC) and the soil dissolved inorganic carbon (SDIC) in whole profiles of saline and alkaline soils by analyzing their contents and ages with radiocarbon dating. The results showed that there is considerable SDIC content in SIC, and the variations of SDIC and SIC contents in the saline soil profile were much larger than that in the alkaline profile. SDIC storage accounted for more than 20% of SIC storage, indicating that more than 1/5 of the inorganic carbon in both saline and alkaline soil is not in non-leachable forms. Deep layer soil contains considerable inorganic carbon, with more than 80% of the soil carbon stored below 1 m, whether for SDIC or SIC. More importantly, SDIC ages were much younger than SIC in both saline soil and alkaline soil. The input rate of SDIC and SIC ranged from 7.58 to 29.54 g C m-2 yr-1 and 1.34 to 5.33 g C m-2 yr-1 respectively for saline soil, and from 1.43 to 4.9 g C m-2 yr-1 and 0.79 to 1.27 g C m-2 yr-1respectively for alkaline soil. The comparison of SDIC and SIC residence time showed that using soil inorganic carbon to estimate soil carbon turnover would obscure an important fraction that contributes to the modern carbon cycle: namely the shorter residence and higher input rate of SDIC. This is especially true for SDIC in deep layers of the soil profile. PMID:24312399

  18. Microalgal bacterial floc properties are improved by a balanced inorganic/organic carbon ratio.

    PubMed

    Van Den Hende, Sofie; Vervaeren, Han; Saveyn, Hans; Maes, Guy; Boon, Nico

    2011-03-01

    Microalgal bacterial floc (MaB-floc) reactors have been suggested as a more sustainable secondary wastewater treatment. We investigated whether MaB-flocs could be used as tertiary treatment. Tertiary influent has a high inorganic/organic carbon ratio, depending on the efficiency of the secondary treatment. In this study, the effect of this inorganic/organic carbon ratio on the MaB-flocs performance was determined, using three sequencing batch photobioreactors. The MaB-flocs were fed with synthetic wastewater containing 84, 42, and 0 mg L(-1) C-KHCO(3) supplemented with 0, 42, 84 mg L(-1) C-sucrose, respectively, representing inorganic versus organic carbon. Bicarbonate significantly decreased the autotrophic index of the MaB-flocs and resulted in poorly settling flocs. Moreover, sole bicarbonate addition led to a high pH of 9.5 and significant lower nitrogen removal efficiencies. Sucrose without bicarbonate resulted in good settling MaB-flocs, high nitrogen removal efficiencies and neutral pH levels. Despite the lower chlorophyll a content of the biomass and the lower in situ oxygen concentration, 92-96% of the soluble COD-sucrose was removed. This study shows that the inorganic/organic carbon ratio of the wastewater is of major importance and that organic carbon is requisite to guarantee a good performance of the MaB-flocs for wastewater treatment. Copyright © 2010 Wiley Periodicals, Inc.

  19. Uptake dynamics of inorganic mercury and methylmercury by the earthworm Pheretima guillemi.

    PubMed

    Dang, Fei; Zhao, Jie; Zhou, Dongmei

    2016-02-01

    Mercury uptake dynamics in the earthworm Pheretima guillemi, including the dissolved uptake rate constant (ku) from pore-water and assimilation efficiencies (AEs) from mercury-contaminated soil, was quantified in this study. Dissolved uptake rate constants were 0.087 and 0.553 L g(-1) d(-1) for inorganic mercury (IHg) and methylmercury (MeHg), respectively. Assimilation efficiency of IHg in field-contaminated soil was 7.2%, lower than 15.4% of spiked soil. In contrast, MeHg exhibited comparable AEs for both field-contaminated and spiked soil (82.4-87.2%). Within the framework of biodynamic model, we further modelled the exposure pathways (dissolved exposure vs soil ingestion) to source the accumulated mercury in Pheretima guillemi. The model showed that the relative importance of soil ingestion to mercury bioaccumulation depended largely on mercury partitioning coefficients (K(d)), and was also influenced by soil ingestion rate of earthworms. In the examined field-contaminated soil, almost (>99%) accumulated IHg and MeHg was predicted to derive from soil ingestion. Therefore, soil ingestion should be carefully considered when assessing mercury exposure risk to earthworms. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Carbonate concretions as a significant component of ancient marine carbon cycles: Insights from paired organic and inorganic carbon isotope analyses of a Cretaceous shale

    NASA Astrophysics Data System (ADS)

    Loyd, S. J.

    2014-12-01

    Carbonate concretions often occur within fine-grained, organic-rich sedimentary rocks. This association reflects the common production of diagenetic minerals through biologic cycling of organic matter. Chemical analysis of carbonate concretions provides the rare opportunity to explore ancient shallow diagenetic environments, which are inherently transient due to progressive burial but are an integral component of the marine carbon cycle. The late Cretaceous Holz Shale (~80 Ma) contains abundant calcite concretions that exhibit textural and geochemical characteristics indicative of relatively shallow formation (i.e., near the sediment-water interface). Sampled concretions contain between 5.4 and 9.8 wt.% total inorganic carbon (TIC), or ~45 and 82 wt.% CaCO3, compared to host shale values which average ~1.5 wt.% TIC. Organic carbon isotope compositions (δ13Corg) are relatively constant in host and concretion samples ranging from ­-26.3 to -24.0‰ (VPDB). Carbonate carbon isotope compositions (δ13Ccarb) range from -22.5 to -3.4‰, indicating a significant but not entirely organic source of carbon. Concretions of the lower Holz Shale exhibit considerably elevated δ13Ccarb values averaging -4.8‰, whereas upper Holz Shale concretions express an average δ13Ccarb value of -17.0‰. If the remaining carbonate for lower Holz Shale concretions is sourced from marine fluids and/or dissolved marine carbonate minerals (e.g., shells), a simple mass balance indicates that ~28% of concretion carbon was sourced from organic matter and ~72% from late Cretaceous marine inorganic carbon (with δ13C ~ +2.5‰). Upper Holz Shale calculations indicate a ~73% contribution from organic matter and a ~27% contribution from inorganic carbon. When normalized for carbonate, organic contents within the concretions are ~2-13 wt.% enriched compared to host contents. This potentially reflects the protective nature of cementation that acts to limit permeability and chemical destruction of

  1. Uptake mechanism for iodine species to black carbon.

    PubMed

    Choung, Sungwook; Um, Wooyong; Kim, Minkyung; Kim, Min-Gyu

    2013-09-17

    Natural organic matter (NOM) plays an important role in determining the fate and transport of iodine species such as iodide (I(-)) and iodate (IO3(-)) in groundwater system. Although NOM exists as diverse forms in environments, prior iodine studies have mainly focused on uptake processes of iodide and iodate to humic materials. This study was conducted to determine the iodide and iodate uptake potential for a particulate NOM (i.e., black carbon [BC]). A laboratory-produced BC and commercial humic acid were used for batch experiments to compare their iodine uptake properties. The BC exhibited >100 times greater uptake capability for iodide than iodate at low pH of ~3, while iodide uptake was negligible for the humic acid. The uptake properties of both solids strongly depend on the initial iodine aqueous concentrations. After uptake reaction of iodide to the BC, X-ray absorption fine structure spectroscopy results indicated that the iodide was converted to electrophilic species, and iodine was covalently bound to carbon atom in polycyclic aromatic hydrocarbons present in the BC. The computed distribution coefficients (i.e., Kd values) suggest that the BC materials retard significantly the transport of iodide at low pH in environmental systems containing even a small amount of BC.

  2. Urea Uptake and Carbon Fixation by Marine Pelagic Bacteria and Archaea during the Arctic Summer and Winter Seasons

    PubMed Central

    Connelly, Tara L.; Baer, Steven E.; Cooper, Joshua T.; Bronk, Deborah A.

    2014-01-01

    How Arctic climate change might translate into alterations of biogeochemical cycles of carbon (C) and nitrogen (N) with respect to inorganic and organic N utilization is not well understood. This study combined 15N uptake rate measurements for ammonium, nitrate, and urea with 15N- and 13C-based DNA stable-isotope probing (SIP). The objective was to identify active bacterial and archeal plankton and their role in N and C uptake during the Arctic summer and winter seasons. We hypothesized that bacteria and archaea would successfully compete for nitrate and urea during the Arctic winter but not during the summer, when phytoplankton dominate the uptake of these nitrogen sources. Samples were collected at a coastal station near Barrow, AK, during August and January. During both seasons, ammonium uptake rates were greater than those for nitrate or urea, and nitrate uptake rates remained lower than those for ammonium or urea. SIP experiments indicated a strong seasonal shift of bacterial and archaeal N utilization from ammonium during the summer to urea during the winter but did not support a similar seasonal pattern of nitrate utilization. Analysis of 16S rRNA gene sequences obtained from each SIP fraction implicated marine group I Crenarchaeota (MGIC) as well as Betaproteobacteria, Firmicutes, SAR11, and SAR324 in N uptake from urea during the winter. Similarly, 13C SIP data suggested dark carbon fixation for MGIC, as well as for several proteobacterial lineages and the Firmicutes. These data are consistent with urea-fueled nitrification by polar archaea and bacteria, which may be advantageous under dark conditions. PMID:25063662

  3. Can frequent precipitation moderate drought impact on peatmoss carbon uptake in northern peatlands?

    NASA Astrophysics Data System (ADS)

    Nijp, Jelmer; Limpens, Juul; Metselaar, Klaas; van der Zee, Sjoerd; Berendse, Frank; Robroek, Bjorn

    2014-05-01

    Northern peatlands represent one of the largest global carbon stores that can potentially be released by water table drawdown during extreme summer droughts. Small precipitation events may moderate negative impacts of deep water levels on carbon uptake by sustaining photosynthesis of peatmoss (Sphagnum spp.), the key species in these ecosystems. We experimentally assessed the importance of the temporal distribution of precipitation for Sphagnum water supply and carbon uptake during a stepwise decrease in water levels in a growth chamber. CO2 exchange and the water balance were measured for intact cores of three peatmoss species representative of three contrasting habitats in northern peatlands (Sphagnum fuscum, S. balticum and S. majus). For shallow water levels, capillary rise was the most important source of water for peatmoss photosynthesis and precipitation did not promote carbon uptake irrespective of peatmoss species. For deep water levels, however, precipitation dominated over capillary rise and moderated adverse effects of drought on carbon uptake by peat mosses. The ability to use the transient water supply by precipitation was species-specific: carbon uptake of S. fuscum increased linearly with precipitation frequency for deep water levels, whereas S. balticum and S. majus showed depressed carbon uptake at intermediate precipitation frequencies. Our results highlight the importance of precipitation for carbon uptake by peatmosses. The potential of precipitation to moderate drought impact, however, is species specific and depends on the temporal distribution of precipitation and water level. These results also suggest that modelling approaches in which water level depth is used as the only state variable determining water availability in the living moss layer and (in)directly linked to Sphagnum carbon uptake may have serious drawbacks. The predictive power of peatland ecosystem models may be reduced when deep water levels prevail, as precipitation

  4. Substantial global carbon uptake by cement carbonation

    NASA Astrophysics Data System (ADS)

    Xi, Fengming; Davis, Steven J.; Ciais, Philippe; Crawford-Brown, Douglas; Guan, Dabo; Pade, Claus; Shi, Tiemao; Syddall, Mark; Lv, Jie; Ji, Lanzhu; Bing, Longfei; Wang, Jiaoyue; Wei, Wei; Yang, Keun-Hyeok; Lagerblad, Björn; Galan, Isabel; Andrade, Carmen; Zhang, Ying; Liu, Zhu

    2016-12-01

    Calcination of carbonate rocks during the manufacture of cement produced 5% of global CO2 emissions from all industrial process and fossil-fuel combustion in 2013. Considerable attention has been paid to quantifying these industrial process emissions from cement production, but the natural reversal of the process--carbonation--has received little attention in carbon cycle studies. Here, we use new and existing data on cement materials during cement service life, demolition, and secondary use of concrete waste to estimate regional and global CO2 uptake between 1930 and 2013 using an analytical model describing carbonation chemistry. We find that carbonation of cement materials over their life cycle represents a large and growing net sink of CO2, increasing from 0.10 GtC yr-1 in 1998 to 0.25 GtC yr-1 in 2013. In total, we estimate that a cumulative amount of 4.5 GtC has been sequestered in carbonating cement materials from 1930 to 2013, offsetting 43% of the CO2 emissions from production of cement over the same period, not including emissions associated with fossil use during cement production. We conclude that carbonation of cement products represents a substantial carbon sink that is not currently considered in emissions inventories.

  5. Does Ocean Color Data Assimilation Improve Estimates of Global Ocean Inorganic Carbon?

    NASA Technical Reports Server (NTRS)

    Gregg, Watson

    2012-01-01

    Ocean color data assimilation has been shown to dramatically improve chlorophyll abundances and distributions globally and regionally in the oceans. Chlorophyll is a proxy for phytoplankton biomass (which is explicitly defined in a model), and is related to the inorganic carbon cycle through the interactions of the organic carbon (particulate and dissolved) and through primary production where inorganic carbon is directly taken out of the system. Does ocean color data assimilation, whose effects on estimates of chlorophyll are demonstrable, trickle through the simulated ocean carbon system to produce improved estimates of inorganic carbon? Our emphasis here is dissolved inorganic carbon, pC02, and the air-sea flux. We use a sequential data assimilation method that assimilates chlorophyll directly and indirectly changes nutrient concentrations in a multi-variate approach. The results are decidedly mixed. Dissolved organic carbon estimates from the assimilation model are not meaningfully different from free-run, or unassimilated results, and comparisons with in situ data are similar. pC02 estimates are generally worse after data assimilation, with global estimates diverging 6.4% from in situ data, while free-run estimates are only 4.7% higher. Basin correlations are, however, slightly improved: r increase from 0.78 to 0.79, and slope closer to unity at 0.94 compared to 0.86. In contrast, air-sea flux of C02 is noticeably improved after data assimilation. Global differences decline from -0.635 mol/m2/y (stronger model sink from the atmosphere) to -0.202 mol/m2/y. Basin correlations are slightly improved from r=O.77 to r=0.78, with slope closer to unity (from 0.93 to 0.99). The Equatorial Atlantic appears as a slight sink in the free-run, but is correctly represented as a moderate source in the assimilation model. However, the assimilation model shows the Antarctic to be a source, rather than a modest sink and the North Indian basin is represented incorrectly as a sink

  6. Interannual stability of organic to inorganic carbon production on a coral atoll

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, Lester; Albright, Rebecca; Hosfelt, Jessica; Nebuchina, Yana; Ninokawa, Aaron; Rivlin, Tanya; Sesboüé, Marine; Wolfe, Kennedy; Caldeira, Ken

    2016-04-01

    Ocean acidification has the potential to adversely affect marine calcifying organisms, with substantial ocean ecosystem impacts projected over the 21st century. Characterizing the in situ sensitivity of calcifying ecosystems to natural variability in carbonate chemistry may improve our understanding of the long-term impacts of ocean acidification. We explore the potential for intensive temporal sampling to isolate the influence of carbonate chemistry on community calcification rates of a coral reef and compare the ratio of organic to inorganic carbon production to previous studies at the same location. Even with intensive temporal sampling, community calcification displays only a weak dependence on carbonate chemistry variability. However, across three years of sampling, the ratio of organic to inorganic carbon production is highly consistent. Although further work is required to quantify the spatial variability associated with such ratios, this suggests that these measurements have the potential to indicate the response of coral reefs to ongoing disturbance, ocean acidification, and climate change.

  7. Inorganic carbon fixation by chemosynthetic ectosymbionts and nutritional transfers to the hydrothermal vent host-shrimp Rimicaris exoculata

    PubMed Central

    Ponsard, Julie; Cambon-Bonavita, Marie-Anne; Zbinden, Magali; Lepoint, Gilles; Joassin, André; Corbari, Laure; Shillito, Bruce; Durand, Lucile; Cueff-Gauchard, Valérie; Compère, Philippe

    2013-01-01

    The shrimp Rimicaris exoculata dominates several hydrothermal vent ecosystems of the Mid-Atlantic Ridge and is thought to be a primary consumer harbouring a chemoautotrophic bacterial community in its gill chamber. The aim of the present study was to test current hypotheses concerning the epibiont's chemoautotrophy, and the mutualistic character of this association. In-vivo experiments were carried out in a pressurised aquarium with isotope-labelled inorganic carbon (NaH13CO3 and NaH14CO3) in the presence of two different electron donors (Na2S2O3 and Fe2+) and with radiolabelled organic compounds (14C-acetate and 3H-lysine) chosen as potential bacterial substrates and/or metabolic by-products in experiments mimicking transfer of small biomolecules from epibionts to host. The bacterial epibionts were found to assimilate inorganic carbon by chemoautotrophy, but many of them (thick filaments of epsilonproteobacteria) appeared versatile and able to switch between electron donors, including organic compounds (heterotrophic acetate and lysine uptake). At least some of them (thin filamentous gammaproteobacteria) also seem capable of internal energy storage that could supply chemosynthetic metabolism for hours under conditions of electron donor deprivation. As direct nutritional transfer from bacteria to host was detected, the association appears as true mutualism. Import of soluble bacterial products occurs by permeation across the gill chamber integument, rather than via the digestive tract. This first demonstration of such capabilities in a decapod crustacean supports the previously discarded hypothesis of transtegumental absorption of dissolved organic matter or carbon as a common nutritional pathway. PMID:22914596

  8. Determination of 14C age of inorganic and organic carbon in ancient Siberian permafrost

    NASA Astrophysics Data System (ADS)

    Onstott, T. C.; Liang, R.; Lau, M.; Vishnivetskaya, T. A.; Lloyd, K. G.; Pfiffner, S. M.; Hodgins, G.; Rivkina, E.

    2017-12-01

    Permafrost represents a large reservoir of ancient carbon that could have an important impact on the global carbon budget during climate warming. Due to the low turnover rate of carbon by microorganisms at subzero temperatures, the persistence of ancient carbon in younger permafrost deposits could also pose challenges for radiocarbon dating of permafrost sediment. We utilized Accelerator Mass Spectrometry to determine the 14C age of inorganic carbon, labile and recalcitrant organic carbon in Siberian permafrost sediment sampled at various depths from 2.9 to 5.6m. The fraction of inorganic carbon (CO2) was collected after acidification using phosphoric acid. The labile (younger) and recalcitrant (old) organic carbon in the subsequent residues were collected after combustion at 400 ºC and 800 ºC, respectively. The percentages of inorganic carbon increased from the youngest (2.9m) to the oldest (5.6m), whereas the fractions for organic carbon varied significantly at different depths. The 14C age determined in the inorganic fraction in the top sample (2.9 m) was 21,760 yr BP and gradually increased to 33,900 yr BP in the relative deeper sediment (3.5 and 5.6 m). Surprisingly, the fraction of "younger" carbon liberated at 400 oC was older than the more recalcitrant and presumably older organic carbon liberated at 800 oC in all cases. Moreover, the 14C age of the younger and older organic carbon fractions did not increase with depth as observed in the carbonate fraction. In particular, the 14C age of the organic carbon in the top sample (38,590-41,700 yr BP) was much older than the deeper samples at depth of 3.5m (18,228-20,158 yr BP) and 5.6m (29,040-38,020 yr BP). It should be noticed that the metabolism of ancient carbon in frozen permafrost may vary at different depths due to the different proportion of necromass and metabolically active microbes. Therefore, additional knowledge about the carbon dynamics of permafrost and more investigation would be required to

  9. Simple and accurate method for determining dissolved inorganic carbon in environmental water by reaction headspace gas chromatography.

    PubMed

    Xie, Wei-Qi; Gong, Yi-Xian; Yu, Kong-Xian

    2018-03-01

    We investigate a simple and accurate method for quantitatively analyzing dissolved inorganic carbon in environmental water by reaction headspace gas chromatography. The neutralization reaction between the inorganic carbon species (i.e. bicarbonate ions and carbonate ions) in environmental water and hydrochloric acid is carried out in a sealed headspace vial, and the carbon dioxide formed from the neutralization reaction, the self-decomposition of carbonic acid, and dissolved carbon dioxide in environmental water is then analyzed by headspace gas chromatography. The data show that the headspace gas chromatography method has good precision (relative standard deviation ≤ 1.63%) and accuracy (relative differences ≤ 5.81% compared with the coulometric titration technique). The headspace gas chromatography method is simple, reliable, and can be well applied in the dissolved inorganic carbon detection in environmental water. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. The transformation of inorganic sulfur compounds and the assimilation of organic and inorganic carbon by the sulfur disproportionating bacterium Desulfocapsa sulfoexigens.

    PubMed

    Frederiksen, Trine-Maria; Finster, Kai

    2004-02-01

    The physiology of the sulfur disproportionator Desulfocapsa sulfoexigens was investigated in batch cultures and in a pH-regulated continuously flushed fermentor system. It was shown that a sulphide scavanger in the form of ferric iron was not obligatory and that the control of pH allowed production of more biomass than was possible in carbonate buffered but unregulated batch cultures. Small amounts of sulphite were produced during disproportionation of elemental sulfur and thiosulphate. In addition, it was shown that in the presence of hydrogen, a respiratory type of process is favored before the disproportionation of sulphite, thiosulphate and elemental sulfur. Sulphate reduction was not observed. D. sulfoexigens assimilated inorganic carbon even in the presence of organic carbon sources. Inorganic carbon assimilation was probably catalyzed by the reverse CO-dehydrogenase pathway, which was supported by the constitutive expression of the gene encoding CO-dehydrogenase in cultures grown in the presence of acetate and by the high carbon fractionation values that are indicative of this pathway.

  11. Spring Hydrology Determines Summer Net Carbon Uptake in Northern Ecosystems

    NASA Technical Reports Server (NTRS)

    Yi, Yonghong; Kimball, John; Reichle, Rolf H.

    2014-01-01

    Increased photosynthetic activity and enhanced seasonal CO2 exchange of northern ecosystems have been observed from a variety of sources including satellite vegetation indices (such as the Normalized Difference Vegetation Index; NDVI) and atmospheric CO2 measurements. Most of these changes have been attributed to strong warming trends in the northern high latitudes (greater than or equal to 50N). Here we analyze the interannual variation of summer net carbon uptake derived from atmospheric CO2 measurements and satellite NDVI in relation to surface meteorology from regional observational records. We find that increases in spring precipitation and snow pack promote summer net carbon uptake of northern ecosystems independent of air temperature effects. However, satellite NDVI measurements still show an overall benefit of summer photosynthetic activity from regional warming and limited impact of spring precipitation. This discrepancy is attributed to a similar response of photosynthesis and respiration to warming and thus reduced sensitivity of net ecosystem carbon uptake to temperature. Further analysis of boreal tower eddy covariance CO2 flux measurements indicates that summer net carbon uptake is positively correlated with early growing-season surface soil moisture, which is also strongly affected by spring precipitation and snow pack based on analysis of satellite soil moisture retrievals. This is attributed to strong regulation of spring hydrology on soil respiration in relatively wet boreal and arctic ecosystems. These results document the important role of spring hydrology in determining summer net carbon uptake and contrast with prevailing assumptions of dominant cold temperature limitations to high-latitude ecosystems. Our results indicate potentially stronger coupling of boreal/arctic water and carbon cycles with continued regional warming trends.

  12. Controls of streamwater dissolved inorganic carbon dynamics in a forested watershed

    USGS Publications Warehouse

    Finlay, J.C.

    2003-01-01

    I investigated controls of stream dissolved inorganic carbon (DIC) sources and cycling along a stream size and productivity gradient in a temperate forested watershed in northern California. Dissolved CO2 (CO2 (aq)) dynamics in heavily shaded streams contrasted strongly with those of larger, open canopied sites. In streams with canopy cover > 97%, CO2 (aq) was highest during baseflow periods (up to 540 ??M) and was negatively related to discharge. Effects of algal photosynthesis on CO2 (aq) were minimal and stream CO2 (aq) was primarily controlled by groundwater CO2 (aq) inputs and degassing losses to the atmosphere. In contrast to the small streams. CO2 (aq) in larger, open-canopied streams was often below atmospheric levels at midday during baseflow and was positively related to discharge. Here, stream CO2 (aq) was strongly influenced by the balance between autotrophic and heterotrophic processes. Dynamics of HCO3- were less complex. HCO3- and Ca2+ were positively correlated, negatively related to discharge, and showed no pattern with stream size. Stable carbon isotope ratios of DIC (i.e. ??13C DIC) increased with stream size and discharge, indicating contrasting sources of DIC to streams and rivers. During summer baseflows, ??13C DIC were 13C-depleted in the smallest streams (minimum of -17.7???) due to the influence of CO2 (aq) derived from microbial respiration and HCO3- derived from carbonate weathering. ??13C DIC were higher (up to -6.6???) in the larger streams and rivers due to invasion of atmospheric CO2 enhanced by algal CO2 (aq) uptake. While small streams were influenced by groundwater inputs, patterns in CO2 (aq) and evidence from stable isotopes demonstrate the strong influence of stream metabolism and CO2 exchange with the atmosphere on stream and river carbon cycles.

  13. Highly selective and stable carbon dioxide uptake in polyindole-derived microporous carbon materials.

    PubMed

    Saleh, Muhammad; Tiwari, Jitendra N; Kemp, K Christain; Yousuf, Muhammad; Kim, Kwang S

    2013-05-21

    Adsorption with solid sorbents is considered to be one of the most promising methods for the capture of carbon dioxide (CO₂) from power plant flue gases. In this study, microporous carbon materials used for CO₂ capture were synthesized by the chemical activation of polyindole nanofibers (PIF) at temperatures from 500 to 800 °C using KOH, which resulted in nitrogen (N)-doped carbon materials. The N-doped carbon materials were found to be microporous with an optimal adsorption pore size for CO₂ of 0.6 nm and a maximum (Brunauer-Emmett-Teller) BET surface area of 1185 m(2) g(-1). The PIF activated at 600 °C (PIF6) has a surface area of 527 m(2) g(-1) and a maximum CO₂ storage capacity of 3.2 mmol g(-1) at 25 °C and 1 bar. This high CO₂ uptake is attributed to its highly microporous character and optimum N content. Additionally, PIF6 material displays a high CO₂ uptake at low pressure (1.81 mmol g(-1) at 0.2 bar and 25 °C), which is the best low pressure CO₂ uptake reported for carbon-based materials. The adsorption capacity of this material remained remarkably stable even after 10 cycles. The isosteric heat of adsorption was calculated to be in the range of 42.7-24.1 kJ mol(-1). Besides the excellent CO₂ uptake and stability, PIF6 also exhibits high selectivity values for CO₂ over N₂, CH₄, and H₂ of 58.9, 12.3, and 101.1 at 25 °C, respectively, and these values are significantly higher than reported values.

  14. Large uncertainty in carbon uptake potential of land-based climate-change mitigation efforts.

    PubMed

    Krause, Andreas; Pugh, Thomas A M; Bayer, Anita D; Li, Wei; Leung, Felix; Bondeau, Alberte; Doelman, Jonathan C; Humpenöder, Florian; Anthoni, Peter; Bodirsky, Benjamin L; Ciais, Philippe; Müller, Christoph; Murray-Tortarolo, Guillermo; Olin, Stefan; Popp, Alexander; Sitch, Stephen; Stehfest, Elke; Arneth, Almut

    2018-07-01

    Most climate mitigation scenarios involve negative emissions, especially those that aim to limit global temperature increase to 2°C or less. However, the carbon uptake potential in land-based climate change mitigation efforts is highly uncertain. Here, we address this uncertainty by using two land-based mitigation scenarios from two land-use models (IMAGE and MAgPIE) as input to four dynamic global vegetation models (DGVMs; LPJ-GUESS, ORCHIDEE, JULES, LPJmL). Each of the four combinations of land-use models and mitigation scenarios aimed for a cumulative carbon uptake of ~130 GtC by the end of the century, achieved either via the cultivation of bioenergy crops combined with carbon capture and storage (BECCS) or avoided deforestation and afforestation (ADAFF). Results suggest large uncertainty in simulated future land demand and carbon uptake rates, depending on the assumptions related to land use and land management in the models. Total cumulative carbon uptake in the DGVMs is highly variable across mitigation scenarios, ranging between 19 and 130 GtC by year 2099. Only one out of the 16 combinations of mitigation scenarios and DGVMs achieves an equivalent or higher carbon uptake than achieved in the land-use models. The large differences in carbon uptake between the DGVMs and their discrepancy against the carbon uptake in IMAGE and MAgPIE are mainly due to different model assumptions regarding bioenergy crop yields and due to the simulation of soil carbon response to land-use change. Differences between land-use models and DGVMs regarding forest biomass and the rate of forest regrowth also have an impact, albeit smaller, on the results. Given the low confidence in simulated carbon uptake for a given land-based mitigation scenario, and that negative emissions simulated by the DGVMs are typically lower than assumed in scenarios consistent with the 2°C target, relying on negative emissions to mitigate climate change is a highly uncertain strategy. © 2018 John

  15. Carbon-1 versus Carbon-3 Linkage of d-Galactose to Porphyrins: Synthesis, Uptake, and Photodynamic Efficiency.

    PubMed

    Pereira, Patrícia M R; Rizvi, Waqar; Bhupathiraju, N V S Dinesh K; Berisha, Naxhije; Fernandes, Rosa; Tomé, João P C; Drain, Charles Michael

    2018-02-21

    The use of glycosylated compounds is actively pursued as a therapeutic strategy for cancer due to the overexpression of various types of sugar receptors and transporters on most cancer cells. Conjugation of saccharides to photosensitizers such as porphyrins provides a promising strategy to improve the selectivity and cell uptake of the photosensitizers, enhancing the overall photosensitizing efficacy. Most porphyrin-carbohydrate conjugates are linked via the carbon-1 position of the carbohydrate because this is the most synthetically accessible approach. Previous studies suggest that carbon-1 galactose derivatives show diminished binding since the hydroxyl group in the carbon-1 position of the sugar is a hydrogen bond acceptor in the galectin-1 sugar binding site. We therefore synthesized two isomeric porphyrin-galactose conjugates using click chemistry: one linked via the carbon-1 of the galactose and one linked via carbon-3. Free base and zinc analogs of both conjugates were synthesized. We assessed the uptake and photodynamic therapeutic (PDT) activity of the two conjugates in both monolayer and spheroidal cell cultures of four different cell lines. For both the monolayer and spheroid models, we observe that the uptake of both conjugates is proportional to the protein levels of galectin-1 and the uptake is suppressed after preincubation with an excess of thiogalactose, as measured by fluorescence spectroscopy. Compared to that of the carbon-1 conjugate, the uptake of the carbon-3 conjugate was greater in cell lines containing high expression levels of galectin-1. After photodynamic activation, MTT and lactate dehydrogenase assays demonstrated that the conjugates induce phototoxicity in both monolayers and spheroids of cancer cells.

  16. Recent increases in terrestrial carbon uptake at little cost to the water cycle.

    PubMed

    Cheng, Lei; Zhang, Lu; Wang, Ying-Ping; Canadell, Josep G; Chiew, Francis H S; Beringer, Jason; Li, Longhui; Miralles, Diego G; Piao, Shilong; Zhang, Yongqiang

    2017-07-24

    Quantifying the responses of the coupled carbon and water cycles to current global warming and rising atmospheric CO 2 concentration is crucial for predicting and adapting to climate changes. Here we show that terrestrial carbon uptake (i.e. gross primary production) increased significantly from 1982 to 2011 using a combination of ground-based and remotely sensed land and atmospheric observations. Importantly, we find that the terrestrial carbon uptake increase is not accompanied by a proportional increase in water use (i.e. evapotranspiration) but is largely (about 90%) driven by increased carbon uptake per unit of water use, i.e. water use efficiency. The increased water use efficiency is positively related to rising CO 2 concentration and increased canopy leaf area index, and negatively influenced by increased vapour pressure deficits. Our findings suggest that rising atmospheric CO 2 concentration has caused a shift in terrestrial water economics of carbon uptake.The response of the coupled carbon and water cycles to anthropogenic climate change is unclear. Here, the authors show that terrestrial carbon uptake increased significantly from 1982 to 2011 and that this increase is largely driven by increased water-use efficiency, rather than an increase in water use.

  17. 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.

  18. Inorganic nanotubes: One contribution of 12 to a Theme 'Nanotechnology of carbon and related materials'

    NASA Astrophysics Data System (ADS)

    Tenne, Reshef; Rao, C. N. R.

    2004-10-01

    Following the discovery of carbon fullerenes and carbon nanotubes, it was hypothesized that nanoparticles of inorganic compounds with layered (two-dimensional) structure, such as MoS2, will not be stable against folding and form nanotubes and fullerene-like structures: IF. The synthesis of numerous other inorganic nanotubes has been reported in recent years. Various techniques for the synthesis of inorganic nanotubes, including high-temperature reactions and strategies based on 'chemie douce' (soft chemistry, i.e. low-temperature) processes, are described. First-principle, density functional theory based calculations are able to provide substantial information on the structure and properties of such nanotubes. Various properties of inorganic nanotubes, including mechanical, electronic and optical properties, are described in brief. Some potential applications of the nanotubes in tribology, protection against impact, (photo)catalysis, batteries, etc., are discussed.

  19. RAPID AND PRECISE METHOD FOR MEASURING STABLE CARBON ISOTOPE RATIOS OF DISSOLVED INORGANIC CARBON

    EPA Science Inventory

    We describe a method for rapid preparation, concentration and stable isotopic analysis of dissolved inorganic carbon (d13C-DIC). Liberation of CO2 was accomplished by placing 100 ?l phosphoric acid and 0.9 ml water in an evacuated 1.7-ml gas chromatography (GC) injection vial. Fo...

  20. The Global Influence of Cloud Optical Thickness on Terrestrial Carbon Uptake

    NASA Astrophysics Data System (ADS)

    Zhu, P.; Cheng, S. J.; Keppel-Aleks, G.; Butterfield, Z.; Steiner, A. L.

    2016-12-01

    Clouds play a critical role in regulating Earth's climate. One important way is by changing the type and intensity of solar radiation reaching the Earth's surface, which impacts plant photosynthesis. Specifically, the presence of clouds modifies photosynthesis rates by influencing the amount of diffuse radiation as well as the spectral distribution of solar radiation. Satellite-derived cloud optical thickness (COT) may provide the observational constraint necessary to assess the role of clouds on ecosystems and terrestrial carbon uptake across the globe. Previous studies using ground-based observations at individual sites suggest that below a COT of 7, there is a greater increase in light use efficiency than at higher COT values, providing evidence for higher carbon uptake rates than expected given the reduction in radiation by clouds. However, the strength of the COT-terrestrial carbon uptake correlation across the globe remains unknown. In this study, we investigate the influence of COT on terrestrial carbon uptake on a global scale, which may provide insights into cloud conditions favorable for plant photosynthesis and improve our estimates of the land carbon sink. Global satellite-derived MODIS data show that tropical and subtropical regions tend to have COT values around or below the threshold during growing seasons. We find weak correlations between COT and GPP with Fluxnet MTE global GPP data, which may be due to the uncertainty of upscaling GPP from individual site measurements. Analysis with solar-induced fluorescence (SIF) as a proxy for GPP is also evaluated. Overall, this work constructs a global picture of the role of COT on terrestrial carbon uptake, including its temporal and spatial variations.

  1. Net carbon uptake has increased through warming-induced changes in temperate forest phenology

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Keenan, Trevor; Gray, Josh; Friedl, Mark

    2014-01-01

    The timing of phenological events exerts a strong control over ecosystem function and leads to multiple feedbacks to the climate system1. Phenology is inherently sensitive to temperature (though the exact sensitivity is disputed2) and recent warming is reported to have led to earlier spring, later autumn3,4 and increased vegetation activity5,6. Such greening could be expected to enhance ecosystem carbon uptake7,8, though reports also suggest decreased uptake for boreal forests4,9. Here we assess changes in phenology of temperate forests over the eastern US during the past two decades, and quantify the resulting changes in forest carbon storage. We combine long-term groundmore » observations of phenology, satellite indices, and ecosystem-scale carbon dioxide flux measurements, along with 18 terrestrial biosphere models. We observe a strong trend of earlier spring and later autumn. In contrast to previous suggestions4,9 we show that carbon uptake through photosynthesis increased considerably more than carbon release through respiration for both an earlier spring and later autumn. The terrestrial biosphere models tested misrepresent the temperature sensitivity of phenology, and thus the effect on carbon uptake. Our analysis of the temperature-phenology-carbon coupling suggests a current and possible future enhancement of forest carbon uptake due to changes in phenology. This constitutes a negative feedback to climate change, and is serving to slow the rate of warming.« less

  2. Carbon isotope fractionation of dissolved inorganic carbon (DIC) due to outgassing of carbon dioxide from a headwater stream

    Treesearch

    Daniel H. Doctor; Carol Kendall; Stephen D. Sebestyen; James B. Shanley; Nobuhito Ohte; Elizabeth W. Boyer

    2008-01-01

    The stable isotopic composition of dissolved inorganic carbon (δ13C-DIC) was investigated as a potential tracer of streamflow generation processes at the Sleepers River Research Watershed, Vermont, USA. Downstream sampling showed δ13C-DIC increased between 3-5% from the stream source to the outlet weir...

  3. Bony fish and their contribution to marine inorganic carbon cycling

    NASA Astrophysics Data System (ADS)

    Salter, Michael; Perry, Chris; Wilson, Rod; Harborne, Alistair

    2016-04-01

    Conventional understanding of the marine inorganic carbon cycle holds that CaCO3 (mostly as low Mg-calcite and aragonite) precipitates in the upper reaches of the ocean and sinks to a point where it either dissolves or is deposited as sediment. Thus, it plays a key role controlling the distribution of DIC in the oceans and in regulating their capacity to absorb atmospheric CO2. However, several aspects of this cycle remain poorly understood and have long perplexed oceanographers, such as the positive alkalinity anomaly observed in the upper water column of many of the world's oceans, above the aragonite and calcite saturation horizons. This anomaly would be explained by extensive dissolution of a carbonate phase more soluble than low Mg-calcite or aragonite, but major sources for such phases remain elusive. Here we highlight marine bony fish as a potentially important primary source of this 'missing' high-solubility CaCO3. Precipitation of CaCO3 takes place within the intestines of all marine bony fish as part of their normal physiological functioning, and global production models suggest it could account for up to 45 % of total new marine CaCO3 production. Moreover, high Mg-calcite containing >25 % mol% MgCO3 - a more soluble phase than aragonite - is a major component of these precipitates. Thus, fish CaCO3 may at least partially explain the alkalinity anomaly in the upper water column. However, the issue is complicated by the fact that carbonate mineralogy actually varies among fish species, with high Mg-calcite (HMC), low Mg-calcite (LMC), aragonite, and amorphous calcium carbonate (ACC) all being common products. Using data from 22 Caribbean fish species, we have generated a novel production model that resolves phase proportions. We evaluate the preservation/dissolution potential of these phases and consider potential implications for marine inorganic carbon cycling. In addition, we consider the dramatic changes in fish biomass structure that have resulted

  4. The influence of dissolved organic carbon on bacterial phosphorus uptake and bacteria-phytoplankton dynamics in two Minnesota lakes

    USGS Publications Warehouse

    Stets, E.G.; Cotner, J.B.

    2008-01-01

    The balance of production in any ecosystem is dependent on the flow of limiting nutrients into either the autotrophic or heterotrophic components of the food web. To understand one of the important controls on the flow of inorganic nutrients between phytoplankton and bacterioplankton in lakes, we manipulated dissolved organic carbon (DOC) in two lakes of different trophic status. We hypothesized that labile DOC additions would increase bacterial phosphorus (P) uptake and decrease the response of phytoplankton to nutrient additions. Supplemental nutrients and carbon (C), nitrogen (N, 1.6 ??mol NH4Cl L-1 d-1), P (0.1 ??mol KH 2PO4 L-1 d-1), and DOC (glucose, 15 ??mol C L-1 d-1) were added twice daily to 8-liter experimental units. We tested the effect of added DOC on chlorophyll concentration, bacterial production, biomass, and P uptake using size-fractionated 33P-PO4 uptake. In the oligotrophic lake, DOC additions stimulated bacterial production and increased bacterial biomass-specific P uptake. Bacteria consumed added DOC, and chlorophyll concentrations were significantly lower in carboys receiving DOC additions. In the eutrophic lake, DOC additions had less of a stimulatory effect on bacterial production and biomass-specific P uptake. DOC accumulated over the time period, and there was little evidence for a DOC-induced decrease in phytoplankton biomass. Bacterial growth approached the calculated ??max and yet did not accumulate biomass, indicating significant biomass losses, which may have constrained bacterial DOC consumption. Excess bacterial DOC consumption in oligotrophic lakes may result in greater bacterial P affinity and enhanced nutrient uptake by the heterotrophic compartment of the food web. On the other hand, constraints on bacterial biomass accumulation in eutrophic lakes, from either viral lysis or bacterial grazing, can allow labile DOC to accumulate, thereby negating the effect of excess DOC on the planktonic food web. ?? 2008, by the American

  5. Inorganic and organic nitrogen uptake by phytoplankton and heterotrophic bacteria in the stratified Mid-Atlantic Bight

    NASA Astrophysics Data System (ADS)

    Bradley, Paul B.; Sanderson, Marta P.; Frischer, Marc E.; Brofft, Jennifer; Booth, Melissa G.; Kerkhof, Lee J.; Bronk, Deborah A.

    2010-08-01

    Little is known about the relative importance of inorganic and organic nitrogen (N) sources in fueling production of phytoplankton versus heterotrophic bacteria on the continental shelf. This issue was addressed during two diel experiments conducted in the Mid-Atlantic Bight at the Long-term Ecosystem Observatory, LEO-15, off southern New Jersey. Uptake of 15N-labeled ammonium (NH 4+), nitrate (NO 3-), and nitrite (NO 2-), and dual-labeled ( 15N and 13C) urea and dissolved free amino acids was measured in water taken from the surface and bottom mixed layers approximately every 4 h over two 24 h periods in July 2002. Two methods were used to quantify 15N uptake rates: (1) traditional filtration into various phytoplankton and bacterial size classes, and (2) flow cytometric (FCM) sorting of autotrophic cells based on the presence of chlorophyll autofluorescence. Due to a strong pycnocline, the nutrient composition was quite distinct between the surface and bottom mixed layers. Dissolved organic N (DON) comprised >99% of the total dissolved N (TDN) pool in surface waters, whereas the bottom-water TDN pool was roughly divided between NH 4+, NO 3-, and DON. Urea was the dominant N form used by all fractions at the surface, and although phytoplankton >3 μm was responsible for most of the urea uptake, bacterial use was detected using stable isotopes and also suggested by ureC sequence analysis. The majority of ureC sequences recovered from the 0.2-0.8 μm fraction belonged to members of the Alphaproteobacteria (46%), whereas those of the 0.8-3.0 μm size class consisted primarily of Cyanobacteria (70%). In contrast to the surface, N uptake in the bottom layer was dominated by NH 4+. The bacterial fraction was responsible for 20-49% of the size-fractionated NH 4+ and NO 3- uptake in surface samples and 36-93% at the bottom. These results suggest that organic N, such as urea, is a viable source of N nutrition to phytoplankton forced to compete with heterotrophic bacteria

  6. Soil Inorganic Carbon Formation: Can Parent Material Overcome Climate?

    NASA Astrophysics Data System (ADS)

    Stanbery, C.; Will, R. M.; Seyfried, M. S.; Benner, S. G.; Flores, A. N.; Guilinger, J.; Lohse, K. A.; Good, A.; Black, C.; Pierce, J. L.

    2014-12-01

    Soil carbon is the third largest carbon reservoir and is composed of both organic and inorganic constituents. However, the storage and flux of soil carbon within the global carbon cycle are not fully understood. While organic carbon is often the focus of research, the factors controlling the formation and dissolution of soil inorganic carbon (SIC) are complex. Climate is largely accepted as the primary control on SIC, but the effects of soil parent material are less clear. We hypothesize that effects of parent material are significant and that SIC accumulation will be greater in soils formed from basalts than granites due to the finer textured soils and more abundant calcium and magnesium cations. This research is being conducted in the Reynolds Creek Experimental Watershed (RCEW) in southwestern Idaho. The watershed is an ideal location because it has a range of gradients in precipitation (250 mm to 1200 mm), ecology (sagebrush steppe to juniper), and parent materials (a wide array of igneous and sedimentary rock types) over a relatively small area. Approximately 20 soil profiles will be excavated throughout the watershed and will capture the effects of differing precipitation amounts and parent material on soil characteristics. Several samples at each site will be collected for analysis of SIC content and grain size distribution using a pressure calcimeter and hydrometers, respectively. Initial field data suggests that soils formed over basalts have a higher concentration of SIC than those on granitic material. If precipitation is the only control on SIC, we would expect to see comparable amounts in soils formed on both rock types within the same precipitation zone. However, field observations suggest that for all but the driest sites, soils formed over granite had no SIC detected while basalt soils with comparable precipitation had measurable amounts of SIC. Grain size distribution appears to be a large control on SIC as the sandier, granitic soils promote

  7. Inorganic carbon addition stimulates snow algae primary productivity

    NASA Astrophysics Data System (ADS)

    Hamilton, T. L.; Havig, J. R.

    2017-12-01

    Earth has experienced glacial/interglacial oscillations throughout its history. Today over 15 million square kilometers (5.8 million square miles) of Earth's land surface is covered in ice including glaciers, ice caps, and the ice sheets of Greenland and Antarctica, most of which are retreating as a consequence of increased atmospheric CO2. Glaciers are teeming with life and supraglacial snow and ice surfaces are often red due to blooms of photoautotrophic algae. Recent evidence suggests the red pigmentation, secondary carotenoids produced in part to thrive under high irradiation, lowers albedo and accelerates melt. However, there are relatively few studies that report the productivity of snow algae communities and the parameters that constrain their growth on snow and ice surfaces. Here, we demonstrate that snow algae primary productivity can be stimulated by the addition of inorganic carbon. We found an increase in light-dependent carbon assimilation in snow algae microcosms amended with increasing amounts of inorganic carbon. Our snow algae communities were dominated by typical cosmopolitan snow algae species recovered from Alpine and Arctic environments. The climate feedbacks necessary to enter and exit glacial/interglacial oscillations are poorly understood. Evidence and models agree that global Snowball events are accompanied by changes in atmospheric CO2 with increasing CO2 necessary for entering periods of interglacial time. Our results demonstrate a positive feedback between increased CO2 and snow algal productivity and presumably growth. With the recent call for bio-albedo effects to be considered in climate models, our results underscore the need for robust climate models to include feedbacks between supraglacial primary productivity, albedo, and atmospheric CO2.

  8. Impact of anthropogenic atmospheric nitrogen and sulfur deposition on ocean acidification and the inorganic carbon system.

    PubMed

    Doney, Scott C; Mahowald, Natalie; Lima, Ivan; Feely, Richard A; Mackenzie, Fred T; Lamarque, Jean-Francois; Rasch, Phil J

    2007-09-11

    Fossil fuel combustion and agriculture result in atmospheric deposition of 0.8 Tmol/yr reactive sulfur and 2.7 Tmol/yr nitrogen to the coastal and open ocean near major source regions in North America, Europe, and South and East Asia. Atmospheric inputs of dissociation products of strong acids (HNO(3) and H2SO(4)) and bases (NH(3)) alter surface seawater alkalinity, pH, and inorganic carbon storage. We quantify the biogeochemical impacts by using atmosphere and ocean models. The direct acid/base flux to the ocean is predominately acidic (reducing total alkalinity) in the temperate Northern Hemisphere and alkaline in the tropics because of ammonia inputs. However, because most of the excess ammonia is nitrified to nitrate (NO(3)(-)) in the upper ocean, the effective net atmospheric input is acidic almost everywhere. The decrease in surface alkalinity drives a net air-sea efflux of CO(2), reducing surface dissolved inorganic carbon (DIC); the alkalinity and DIC changes mostly offset each other, and the decline in surface pH is small. Additional impacts arise from nitrogen fertilization, leading to elevated primary production and biological DIC drawdown that reverses in some places the sign of the surface pH and air-sea CO(2) flux perturbations. On a global scale, the alterations in surface water chemistry from anthropogenic nitrogen and sulfur deposition are a few percent of the acidification and DIC increases due to the oceanic uptake of anthropogenic CO(2). However, the impacts are more substantial in coastal waters, where the ecosystem responses to ocean acidification could have the most severe implications for mankind.

  9. Sustainable carbon uptake - important ecosystem service within sustainable forest management

    NASA Astrophysics Data System (ADS)

    Zorana Ostrogović Sever, Maša; Anić, Mislav; Paladinić, Elvis; Alberti, Giorgio; Marjanović, Hrvoje

    2016-04-01

    Even-aged forest management with natural regeneration under continuous cover (i.e. close to nature management) is considered to be sustainable regarding the yield, biodiversity and stability of forest ecosystems. Recently, in the context of climate change, there is a raising question of sustainable forest management regarding carbon uptake. Aim of this research was to explore whether current close to nature forest management approach in Croatia can be considered sustainable in terms of carbon uptake throughout the life-time of Pedunculate oak forest. In state-owned managed forest a chronosequence experiment was set up and carbon stocks in main ecosystem pools (live biomass, dead wood, litter and mineral soil layer), main carbon fluxes (net primary production, soil respiration (SR), decomposition) and net ecosystem productivity were estimated in eight stands of different age (5, 13, 38, 53, 68, 108, 138 and 168 years) based on field measurements and published data. Air and soil temperature and soil moisture were recorded on 7 automatic mini-meteorological stations and weekly SR measurements were used to parameterize SR model. Carbon balance was estimated at weekly scale for the growing season 2011 (there was no harvesting), as well as throughout the normal rotation period of 140 years (harvesting was included). Carbon stocks in different ecosystem pools change during a stand development. Carbon stocks in forest floor increase with stand age, while carbon stocks in dead wood are highest in young and older stands, and lowest in middle-aged, mature stands. Carbon stocks in mineral soil layer were found to be stable across chronosequence with no statistically significant age-dependent trend. Pedunculate Oak stand, assuming successful regeneration, becomes carbon sink very early in a development phase, between the age of 5 and 13 years, and remains carbon sink even after the age of 160 years. Greatest carbon sink was reached in the stand aged 53 years. Obtained results

  10. Inorganic nanotubes.

    PubMed

    Tenne, Reshef; Rao, C N R

    2004-10-15

    Following the discovery of carbon fullerenes and carbon nanotubes, it was hypothesized that nanoparticles of inorganic compounds with layered (two-dimensional) structure, such as MoS(2), will not be stable against folding and form nanotubes and fullerene-like structures: IF. The synthesis of numerous other inorganic nanotubes has been reported in recent years. Various techniques for the synthesis of inorganic nanotubes, including high-temperature reactions and strategies based on 'chemie douce' (soft chemistry, i.e. low-temperature) processes, are described. First-principle, density functional theory based calculations are able to provide substantial information on the structure and properties of such nanotubes. Various properties of inorganic nanotubes, including mechanical, electronic and optical properties, are described in brief. Some potential applications of the nanotubes in tribology, protection against impact, (photo)catalysis, batteries, etc., are discussed.

  11. Impact of atmospheric and terrestrial CO2 feedbacks on fertilization-induced marine carbon uptake

    NASA Astrophysics Data System (ADS)

    Oschlies, A.

    2009-04-01

    The sensitivity of oceanic CO2 uptake to alterations in the marine biological carbon pump, such as brought about by natural or purposeful ocean fertilization, has repeatedly been investigated by studies employing numerical biogeochemical ocean models. It is shown here that the results of such ocean-centered studies are very sensitive to the assumption made about the response of the carbon reservoirs on the atmospheric side of the sea surface. Assumptions made include prescribed atmospheric pCO2, an interactive atmospheric CO2 pool exchanging carbon with the ocean but not with the terrestrial biosphere, and an interactive atmosphere that exchanges carbon with both oceanic and terrestrial carbon pools. The impact of these assumptions on simulated annual to millennial oceanic carbon uptake is investigated for a hypothetical increase in the C:N ratio of the biological pump and for an idealized enhancement of phytoplankton growth. Compared to simulations with interactive atmosphere, using prescribed atmospheric pCO2 overestimates the sensitivity of the oceanic CO2 uptake to changes in the biological pump, by about 2%, 25%, 100%, and >500% on annual, decadal, centennial, and millennial timescales, respectively. Adding an interactive terrestrial carbon pool to the atmosphere-ocean model system has a small effect on annual timescales, but increases the simulated fertilization-induced oceanic carbon uptake by about 4%, 50%, and 100% on decadal, centennial, and millennial timescales, respectively. On longer than decadal timescales, a substantial fraction of oceanic carbon uptake induced by natural or purposeful ocean fertilization may not come from the atmosphere but from the terrestrial biosphere.

  12. Impact of atmospheric and terrestrial CO2 feedbacks on fertilization-induced marine carbon uptake

    NASA Astrophysics Data System (ADS)

    Oschlies, A.

    2009-08-01

    The sensitivity of oceanic CO2 uptake to alterations in the marine biological carbon pump, such as brought about by natural or purposeful ocean fertilization, has repeatedly been investigated by studies employing numerical biogeochemical ocean models. It is shown here that the results of such ocean-centered studies are very sensitive to the assumption made about the response of the carbon reservoirs on the atmospheric side of the sea surface. Assumptions made include prescribed atmospheric pCO2, an interactive atmospheric CO2 pool exchanging carbon with the ocean but not with the terrestrial biosphere, and an interactive atmosphere that exchanges carbon with both oceanic and terrestrial carbon pools. The impact of these assumptions on simulated annual to millennial oceanic carbon uptake is investigated for a hypothetical increase in the C:N ratio of the biological pump and for an idealized enhancement of phytoplankton growth. Compared to simulations with interactive atmosphere, using prescribed atmospheric pCO2 overestimates the sensitivity of the oceanic CO2 uptake to changes in the biological pump, by about 2%, 25%, 100%, and >500% on annual, decadal, centennial, and millennial timescales, respectively. The smaller efficiency of the oceanic carbon uptake under an interactive atmosphere is due to the back flux of CO2 that occurs when atmospheric CO2 is reduced. Adding an interactive terrestrial carbon pool to the atmosphere-ocean model system has a small effect on annual timescales, but increases the simulated fertilization-induced oceanic carbon uptake by about 4%, 50%, and 100% on decadal, centennial, and millennial timescales, respectively, for pCO2 sensitivities of the terrestrial carbon storage in the middle range of the C4MIP models (Friedlingstein et al., 2006). For such sensitivities, a substantial fraction of oceanic carbon uptake induced by natural or purposeful ocean fertilization originates, on timescales longer than decades, not from the atmosphere

  13. Drivers of Phosphorus Uptake by Barley Following Secondary Resource Application

    PubMed Central

    Brod, Eva; Øgaard, Anne Falk; Krogstad, Tore; Haraldsen, Trond Knapp; Frossard, Emmanuel; Oberson, Astrid

    2016-01-01

    Minable rock phosphate is a finite resource. Replacing mineral phosphorus (P) fertilizer with P-rich secondary resources is one way to manage P more efficiently, but the importance of physicochemical and microbial soil processes induced by secondary resources for plant P uptake is still poorly understood. Using radioactive-labeling techniques, the fertilization effects of dairy manure, fish sludge, meat bone meal, and wood ash were studied as P uptake by barley after 44 days and compared with those of water-soluble mineral P (MinP) and an unfertilized control (NoP) in a pot experiment with an agricultural soil containing little available P at two soil pH levels, approximately pH 5.3 (unlimed soil) and pH 6.2 (limed soil). In a parallel incubation experiment, the effects of the secondary resources on physicochemical and microbial soil processes were studied. The results showed that the relative agronomic efficiency compared with MinP decreased in the order: manure ≥fish sludge ≥wood ash ≥meat bone meal. The solubility of inorganic P in secondary resources was the main driver for P uptake by barley (Hordeum vulgare). The effects of secondary resources on physicochemical and microbial soil processes were of little overall importance. Application of organic carbon with manure resulted in microbial P immobilization and decreased uptake by barley of P derived from the soil. On both soils, P uptake by barley was best explained by a positive linear relationship with the H2O + NaHCO3-soluble inorganic P fraction in fertilizers or by a linear negative relationship with the HCl-soluble inorganic P fraction in fertilizers. PMID:27243015

  14. Carbonation and CO{sub 2} uptake of concrete

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Keun-Hyeok, E-mail: yangkh@kgu.ac.kr; Seo, Eun-A, E-mail: ssooaa@naver.com; Tae, Sung-Ho, E-mail: jnb55@hanyang.ac.kr

    This study developed a reliable procedure to assess the carbon dioxide (CO{sub 2}) uptake of concrete by carbonation during the service life of a structure and by the recycling of concrete after demolition. To generalize the amount of absorbable CO{sub 2} per unit volume of concrete, the molar concentration of carbonatable constituents in hardened cement paste was simplified as a function of the unit content of cement, and the degree of hydration of the cement paste was formulated as a function of the water-to-cement ratio. The contribution of the relative humidity, type of finishing material for the concrete surface, andmore » the substitution level of supplementary cementitious materials to the CO{sub 2} diffusion coefficient in concrete was reflected using various correction factors. The following parameters varying with the recycling scenario were also considered: the carbonatable surface area of concrete crusher-runs and underground phenomena of the decreased CO{sub 2} diffusion coefficient and increased CO{sub 2} concentration. Based on the developed procedure, a case study was conducted for an apartment building with a principal wall system and an office building with a Rahmen system, with the aim of examining the CO{sub 2} uptake of each structural element under different exposure environments during the service life and recycling of the building. As input data necessary for the case study, data collected from actual surveys conducted in 2012 in South Korea were used, which included data on the surrounding environments, lifecycle inventory database, life expectancy of structures, and recycling activity scenario. Ultimately, the CO{sub 2} uptake of concrete during a 100-year lifecycle (life expectancy of 40 years and recycling span of 60 years) was estimated to be 15.5%–17% of the CO{sub 2} emissions from concrete production, which roughly corresponds to 18%–21% of the CO{sub 2} emissions from the production of ordinary Portland cement. - Highlights:

  15. Nutrient uptake of NPK and result of some rice varieties in tidal land by using combination of organic and inorganic fertilizer

    NASA Astrophysics Data System (ADS)

    Marlina, Neni; Rompas, Joni Phillep; Marlina, Musbik

    2017-09-01

    Rice planting in tidal land has two main problems: iron (Fe) which has the potential to poison rice and low nutrient availability. Azospirillum enriched chicken manure and phosphate solvent bacteria (Biological Organic Fertilizer = BOF) is an option to overcome iron toxicity and as a source of nutrition. The objective of the study was to obtain a combination of biological organic fertilizers and balanced inorganic fertilizers in reducing doses of inorganic fertilizers, increasing NPK nutrient uptake and yield of several rice varieties in tidal land. This research used Factorial RAK with 25 treatment combinations that were repeated three times. Factor I is a combination of BOF and anorganic fertilizer with 5 levels of treatment (no inorganic fertilizers, BOF 400 kg / ha with inorganic fertilizer 25% NPK, BOF 400 kg / ha with inorganic fertilizer 50% NPK and BOF 400 kg / ha with fertilizer Inorganic 75% NPK). Factor II is several rice varieties (IPB 4S, Martapura, Margasari, Inpara 5, Inpara 7). The results showed that organic fertilizer 400 kg / ha can reduce the use of inorganic fertilizer by 75% of NPK fertilizer. The highest NPK nutrient absorption is in the treatment of organic fertilizer 400 kg / ha and inorganic fertilizer 25% of NPK fertilizer. Production of biological organic fertilizer 400 kg / ha with inorganic fertilizer 25% NPK and 4B IPB varieties 727.77% higher when compared with without the provision of organic fertilizer with Inpara 5 varieties.

  16. Acclimation to Very Low CO2: Contribution of Limiting CO2 Inducible Proteins, LCIB and LCIA, to Inorganic Carbon Uptake in Chlamydomonas reinhardtii1[OPEN

    PubMed Central

    Spalding, Martin H.

    2014-01-01

    The limiting-CO2 inducible CO2-concentrating mechanism (CCM) of microalgae represents an effective strategy to capture CO2 when its availability is limited. At least two limiting-CO2 acclimation states, termed low CO2 and very low CO2, have been demonstrated in the model microalga Chlamydomonas reinhardtii, and many questions still remain unanswered regarding both the regulation of these acclimation states and the molecular mechanism underlying operation of the CCM in these two states. This study examines the role of two proteins, Limiting CO2 Inducible A (LCIA; also named NAR1.2) and LCIB, in the CCM of C. reinhardtii. The identification of an LCIA-LCIB double mutant based on its inability to survive in very low CO2 suggests that both LCIA and LCIB are critical for survival in very low CO2. The contrasting effects of individual mutations in LCIB and LCIA compared with the effects of LCIB-LCIA double mutations on growth and inorganic carbon-dependent photosynthetic O2 evolution reveal distinct roles of LCIA and LCIB in the CCM. Although both LCIA and LCIB are essential for very low CO2 acclimation, LCIB appears to function in a CO2 uptake system, whereas LCIA appears to be associated with a HCO3− transport system. The contrasting and complementary roles of LCIA and LCIB in acclimation to low CO2 and very low CO2 suggest a possible mechanism of differential regulation of the CCM based on the inhibition of HCO3− transporters by moderate to high levels of CO2. PMID:25336519

  17. Ecological Uptake and Depuration of Carbon Nanotubes by Lumbriculus variegatus

    PubMed Central

    Petersen, Elijah J.; Huang, Qingguo; Weber, Walter J.

    2008-01-01

    Background Carbon nanotubes represent a class of nanomaterials having broad application potentials and documented cellular uptake and ecotoxicological effects that raise the possibility that they may bioaccumulate in living organisms. Objectives Radioactively labeled nanotubes were synthesized using a novel methane chemical vapor deposition procedure. Single-walled carbon nanotubes (SWNTs), multiwalled carbon nanotubes (MWNTs), and pyrene were spiked to sediment samples, and the respective uptake and depuration of these nanotubes and pyrene were assessed by the oligochaete, Lumbriculus variegatus. Results 14C-labeled carbon nanotubes were developed for these experiments to overcome significant previous limitations for quantifying nanotube materials in environmental and biological media. Biota-sediment accumulation factors for SWNTs and MWNTs were observed to be almost an order of magnitude lower than those for pyrene, a four-ringed polycyclic aromatic hydrocarbon (PAH). The depuration behaviors of the oligochaete suggested that the nanotubes detected in these organisms were associated with sediments remaining in the organism guts and not absorbed into cellular tissues as was the pyrene. The results suggest that, unlike PAHs, purified carbon nanotubes do not readily absorb into organism tissues. PMID:18414633

  18. Recent drought effects on ecosystem carbon uptake in California ecosystems

    NASA Astrophysics Data System (ADS)

    Chen, M.; Guan, K.; Brodrick, P. G.; Berry, J. A.; Asner, G. P.

    2016-12-01

    California is one of the Earth's most biodiverse places and most of California has experienced an extreme (millennium scale) drought in the period of 2012-2015. Although the effect of the drought on the water resources have been well studied, the responses of ecosystems has not been explored in this detail. This study used advanced remotely sensed data (e.g., remotely sensed vegetation indices and solar-induced fluorescence), an ecosystem model, and model-data fusion techniques to study the impacts of the severe drought on ecosystem carbon uptakes in California. We have found that: (1) the drought has significantly suppressed carbon uptake and light use efficiency in California ecosystems - except in the semi-deserts, and the moist forests in the northern coast; (2) effects on the photosynthetic capacity of the ecosystems extends after the drought is relieved; and (3) the drought has shifted both the timing and magnitude of the seasonality of the carbon uptake in non-forested regions. These findings provide a better understanding of the impacts of droughts, and provide an improved basis for prediction of ecosystem responses under a more extreme climate in the future.

  19. Seasonal Forcing of Summer Dissolved Inorganic Carbon and Chlorophyll a on the Western Shelf of the Antarctic Peninsula

    DTIC Science & Technology

    2010-03-30

    Click Here for Full Article Seasonal forcing of summer dissolved inorganic carbon and chlorophyll a on the western shelf of the Antarctic Peninsula... season characterized by decreased spring sea ice cover or nearshore accumulation of phytoplankton in association with sea ice. The impact of these wind...Stammerjohn, and O. Schofield (2010), Seasonal forcing of summer dissolved inorganic carbon and chlorophyll a on the western shelf of the Antarctic

  20. Influence of water chemistry and natural organic matter on active and passive uptake of inorganic mercury by gills of rainbow trout (Oncorhynchus mykiss).

    PubMed

    Klinck, Joel; Dunbar, Michael; Brown, Stephanie; Nichols, Joel; Winter, Anna; Hughes, Christopher; Playle, Richard C

    2005-03-25

    To distinguish physiologically regulated uptake from passive uptake of inorganic Hg in fish, rainbow trout (Oncorhynchus mykiss) were exposed to inorganic Hg (0.5, 1, or 2 microM total Hg) in ion-poor water with various treatments. Addition of ions to the water (mM concentrations of Ca, K, Cl) did not consistently alter Hg accumulation by trout gills, although there was a trend to higher Hg accumulation at higher ion concentrations. The apical Ca channel blockers Verapamil and lanthanum also did not consistently affect Hg accumulation by trout gills. Pre-treatment of trout with the Na channel blocker Phenamil decreased Hg uptake by about half. These results suggest a combination of physiologically regulated and passive uptake of Hg by trout gills. Strong complexing agents of Hg (EDTA, NTA, ethylenediamine, cysteine) decreased Hg-binding by trout gills in a dose-dependent manner. From these data, a conditional equilibrium binding constant for Hg to the gills was estimated as logK(Hg-gill) = 18.0, representing very strong binding of Hg to the gills. This value is a first step in creating a biotic ligand model (BLM) for inorganic Hg and fish. Natural organic matter (2-10 mg C/L) also decreased Hg-binding by trout gills, although mM concentrations of Na, K, and Cl interfered with this effect. At low concentrations of these ions, natural organic matter samples isolated from various sources bound Hg to similar degrees, as judged by Hg accumulation by trout gills. A conditional binding constant to natural organic matter (NOM) was estimated as logK(Hg-NOM) = 18.0 with about 0.5 micromol binding sites per mg C, representing strong binding of Hg to NOM.

  1. Carbon isotope signature of dissolved inorganic carbon (DIC) in precipitation and atmospheric CO2.

    PubMed

    Górka, Maciej; Sauer, Peter E; Lewicka-Szczebak, Dominika; Jędrysek, Mariusz-Orion

    2011-01-01

    This paper describes results of chemical and isotopic analysis of inorganic carbon species in the atmosphere and precipitation for the calendar year 2008 in Wrocław (SW Poland). Atmospheric air samples (collected weekly) and rainwater samples (collected after rain episodes) were analysed for CO2 and dissolved inorganic carbon (DIC) concentrations and for δ13C composition. The values obtained varied in the ranges: atmospheric CO2: 337-448 ppm; δ13CCO2 from -14.4 to -8.4‰; DIC in precipitation: 0.6-5.5 mg dm(-3); δ13CDIC from -22.2 to +0.2‰. No statistical correlation was observed between the concentration and δ13C value of atmospheric CO2 and DIC in precipitation. These observations contradict the commonly held assumption that atmospheric CO2 controls the DIC in precipitation. We infer that DIC is generated in ambient air temperatures, but from other sources than the measured atmospheric CO2. The calculated isotopic composition of a hypothetical CO2 source for DIC forming ranges from -31.4 to -11.0‰, showing significant seasonal variations accordingly to changing anthropogenic impact and atmospheric mixing processes. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Hybrid protein-inorganic nanoparticles: From tumor-targeted drug delivery to cancer imaging.

    PubMed

    Elzoghby, Ahmed O; Hemasa, Ayman L; Freag, May S

    2016-12-10

    Recently, a great interest has been paid to the development of hybrid protein-inorganic nanoparticles (NPs) for drug delivery and cancer diagnostics in order to combine the merits of both inorganic and protein nanocarriers. This review primarily discusses the most outstanding advances in the applications of the hybrids of naturally-occurring proteins with iron oxide, gadolinium, gold, silica, calcium phosphate NPs, carbon nanotubes, and quantum dots in drug delivery and cancer imaging. Various strategies that have been utilized for the preparation of protein-functionalized inorganic NPs and the mechanisms involved in the drug loading process are discussed. How can the protein functionalization overcome the limitations of colloidal stability, poor dispersibility and toxicity associated with inorganic NPs is also investigated. Moreover, issues relating to the influence of protein hybridization on the cellular uptake, tumor targeting efficiency, systemic circulation, mucosal penetration and skin permeation of inorganic NPs are highlighted. A special emphasis is devoted to the novel approaches utilizing the protein-inorganic nanohybrids in combined cancer therapy, tumor imaging, and theranostic applications as well as stimuli-responsive drug release from the nanohybrids. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Increase in observed net carbon dioxide uptake by land and oceans during the past 50 years.

    PubMed

    Ballantyne, A P; Alden, C B; Miller, J B; Tans, P P; White, J W C

    2012-08-02

    One of the greatest sources of uncertainty for future climate predictions is the response of the global carbon cycle to climate change. Although approximately one-half of total CO(2) emissions is at present taken up by combined land and ocean carbon reservoirs, models predict a decline in future carbon uptake by these reservoirs, resulting in a positive carbon-climate feedback. Several recent studies suggest that rates of carbon uptake by the land and ocean have remained constant or declined in recent decades. Other work, however, has called into question the reported decline. Here we use global-scale atmospheric CO(2) measurements, CO(2) emission inventories and their full range of uncertainties to calculate changes in global CO(2) sources and sinks during the past 50 years. Our mass balance analysis shows that net global carbon uptake has increased significantly by about 0.05 billion tonnes of carbon per year and that global carbon uptake doubled, from 2.4 ± 0.8 to 5.0 ± 0.9 billion tonnes per year, between 1960 and 2010. Therefore, it is very unlikely that both land and ocean carbon sinks have decreased on a global scale. Since 1959, approximately 350 billion tonnes of carbon have been emitted by humans to the atmosphere, of which about 55 per cent has moved into the land and oceans. Thus, identifying the mechanisms and locations responsible for increasing global carbon uptake remains a critical challenge in constraining the modern global carbon budget and predicting future carbon-climate interactions.

  4. Ultraviolet-B radiation effects on inorganic nitrogen uptake by natural assemblages of oceanic plankton

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Behrenfeld, M.J.; Lean, D.R.S.; Lee, H. II

    1995-02-01

    Ultraviolet-B radiation (UVBR: 290-320 nm) inhibited ammonium uptake ({rho}{sub NH4}) and nitrate uptake ({rho}{sub NO3}) in natural plankton assemblages collected during a transect from 37{degrees}N to 55{degrees}N in the Pacific Ocean. Comparison of responses in {rho}{sub NH4} to ambient solar- and lamp-enhanced UVBR spectra allowed calculation of an action spectrum for {rho}{sub NH4} inhibition. The slope of the action spectrum for {rho}{sub NH4} is half as steep as action spectra for UVBR inhibition of photosynthetic carbon uptake. Consequently, UVBR-induced photoinhibition of {rho}{sub NH4} extends to greater depths than inhibition of carbon fixation due to the greater relative effect of longermore » UVBR wavelengths. Inhibition of {rho}{sub NH4} was dependent upon UVBR dose when doses were weighted by the {rho}{sub NH4} action spectrum. Dependence of UVBR inhibition of {rho}{sub NH4} on dose rate was not apparent. We found that near-surface {rho}{sub NH4} and {rho}{sub NO3} can be overestimated in excess of 50% when measured using standard incubation vessels made of UVBR-absorbing materials such as polycarbonate. 68 refs., 9 figs., 1 tab.« less

  5. Inorganic carbon turnover caused by digestion of carbonate sands and metabolic activity of holothurians

    NASA Astrophysics Data System (ADS)

    Schneider, Kenneth; Silverman, Jacob; Kravitz, Ben; Rivlin, Tanya; Schneider-Mor, Aya; Barbosa, Sergio; Byrne, Maria; Caldeira, Ken

    2013-11-01

    Recent measurements have shown that holothurians (sea cucumbers) may play an important role in the cycling of CaCO3 in tropical coral reef systems through ingestion and processing of carbonate sediment. In this report, we present estimates of inorganic carbon turnover rates determined from laboratory incubations of Holothuria atra, Holothuria leucospilota and Stichopus herrmanni. The pH values of the gut lumen ranged from 7.0 to 7.6 when digestive tracts were filled with sediment compared with 6.1-6.7 in animals with empty digestive tracts. Empty gut volume estimates for H. atra and S. herrmanni were 36 ± 4 mL and 151 ± 14 mL, respectively. Based on these measurements and the density and porosity of carbonate sediments of coral reefs, it is estimated that these species process 19 ± 2 kg and 80 ± 7 kg CaCO3 sand yr-1 per individual, respectively. The annual CaCO3 dissolution rates per H. atra and S. herrmanni individual are estimated to be 6.5 ± 1.9 g and 9.6 ± 1.4 g, respectively, suggesting that 0.05 ± 0.02% and 0.1 ± 0.02% of the CaCO3 processed through their gut annually is dissolved. During incubations the CaCO3 dissolution of the fecal casts was 0.07 ± 0.01%, 0.04 ± 0.01% and 0.21 ± 0.05% for H. atra, H. leucospilota and S. herrmanni, respectively. The CaCO3 saturation state in the incubation seawater decreased markedly due to a greater increase in dissolved inorganic carbon (DIC) relative to total alkalinity (AT) as a result of respiration by the animals. Our results support the hypothesis that deposit feeders such as sea cucumbers play an important ecological role in the coral reef CaCO3 cycle.

  6. [Correlation Among Soil Organic Carbon, Soil Inorganic Carbon and the Environmental Factors in a Typical Oasis in the Southern Edge of the Tarim Basin].

    PubMed

    Gong, Lu; Zhu, Mei-ling; Liu, Zeng-yuan; Zhang, Xue-ni; Xie, Li-na

    2016-04-15

    We analyzed the differentiation among the environmental factors and soil organic/inorganic carbon contents of irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil by classical statistics methods, and studied the correlation between soil carbon contents and the environmental factor by redundancy analysis (RDA) in a typical oasis of Yutian in the southern edge of the Tarim Basin. The results showed that the average contents of soil organic carbon and soil inorganic carbon were 2.51 g · kg⁻¹ and 25.63 g · kg⁻¹ respectively. The soil organic carbon content of the irrigated desert soil was significantly higher than those of brown desert soil, saline soil and aeolian sandy soil, while the inorganic carbon content of aeolian sandy soil was significantly higher than those of other soil types. The soil moisture and nutrient content were the highest in the irrigated desert soil and the lowest in the aeolian sandy sail. All soil types had high degree of salinization except the irrigated desert soil. The RDA results showed that the impacts of environmental factors on soil carbon contents ranked in order of importance were total nitrogen > available phosphorus > soil moisture > ground water depth > available potassium > pH > total salt. The soil carbon contents correlated extremely significantly with total nitrogen, available phosphorus, soil moisture and ground water depth (P < 0.01), and it correlated significantly with available potassium and pH (P < 0.05). There was no significant correlation between soil carbon contents and other environmental factors (P > 0.05).

  7. Sorptive Uptake Studies of an Aryl-Arsenical with Iron Oxide Composites on an Activated Carbon Support

    PubMed Central

    Kwon, Jae H.; Wilson, Lee D.; Sammynaiken, Ramaswami

    2014-01-01

    Sorption uptake kinetics and equilibrium studies for 4-hydroxy-3-nitrobenzene arsonic acid (roxarsone) was evaluated with synthetic magnetite (Mag-P), commercial magnetite (Mag-C), magnetite 10%, 19%, and 32% composite material (CM-10, -19, -32) that contains granular activated carbon (GAC), and synthetic goethite at pH 7.00 in water at 21 °C for 24 h. GAC showed the highest sorptive removal of roxarsone and the relative uptake for each sorbent material with roxarsone are listed in descending order as follows: GAC (471 mg/g) > goethite (418 mg/g) > CM-10 (377 mg/g) CM-19 (254 mg/g) > CM-32 (227 mg/g) > Mag-P (132 mg/g) > Mag-C (29.5 mg/g). The As (V) moiety of roxarsone is adsorbed onto the surface of the iron oxide/oxyhydrate and is inferred as inner-sphere surface complexes; monodentate-mononuclear, bidentate-mononuclear, and bidentate-binuclear depending on the protolytic speciation of roxarsone. The phenyl ring of roxarsone provides the primary driving force for the sorptive interaction with the graphene surface of GAC and its composites. Thus, magnetite composites are proposed as multi-purpose adsorbents for the co-removal of inorganic and organic arsenicals due to the presence of graphenic and iron oxide active adsorption sites. PMID:28788545

  8. Elevated CO2 maintains grassland net carbon uptake under a future heat and drought extreme

    PubMed Central

    Roy, Jacques; Picon-Cochard, Catherine; Augusti, Angela; Benot, Marie-Lise; Thiery, Lionel; Darsonville, Olivier; Landais, Damien; Piel, Clément; Defossez, Marc; Devidal, Sébastien; Escape, Christophe; Ravel, Olivier; Fromin, Nathalie; Volaire, Florence; Milcu, Alexandru; Bahn, Michael; Soussana, Jean-François

    2016-01-01

    Extreme climatic events (ECEs) such as droughts and heat waves are predicted to increase in intensity and frequency and impact the terrestrial carbon balance. However, we lack direct experimental evidence of how the net carbon uptake of ecosystems is affected by ECEs under future elevated atmospheric CO2 concentrations (eCO2). Taking advantage of an advanced controlled environment facility for ecosystem research (Ecotron), we simulated eCO2 and extreme cooccurring heat and drought events as projected for the 2050s and analyzed their effects on the ecosystem-level carbon and water fluxes in a C3 grassland. Our results indicate that eCO2 not only slows down the decline of ecosystem carbon uptake during the ECE but also enhances its recovery after the ECE, as mediated by increases of root growth and plant nitrogen uptake induced by the ECE. These findings indicate that, in the predicted near future climate, eCO2 could mitigate the effects of extreme droughts and heat waves on ecosystem net carbon uptake. PMID:27185934

  9. Acidification, not carbonation, is the major regulator of carbon fluxes in the coccolithophore Emiliania huxleyi.

    PubMed

    Kottmeier, Dorothee M; Rokitta, Sebastian D; Rost, Björn

    2016-07-01

    A combined increase in seawater [CO2 ] and [H(+) ] was recently shown to induce a shift from photosynthetic HCO3 (-) to CO2 uptake in Emiliania huxleyi. This shift occurred within minutes, whereas acclimation to ocean acidification (OA) did not affect the carbon source. To identify the driver of this shift, we exposed low- and high-light acclimated E. huxleyi to a matrix of two levels of dissolved inorganic carbon (1400, 2800 μmol kg(-1) ) and pH (8.15, 7.85) and directly measured cellular O2 , CO2 and HCO3 (-) fluxes under these conditions. Exposure to increased [CO2 ] had little effect on the photosynthetic fluxes, whereas increased [H(+) ] led to a significant decline in HCO3 (-) uptake. Low-light acclimated cells overcompensated for the inhibition of HCO3 (-) uptake by increasing CO2 uptake. High-light acclimated cells, relying on higher proportions of HCO3 (-) uptake, could not increase CO2 uptake and photosynthetic O2 evolution consequently became carbon-limited. These regulations indicate that OA responses in photosynthesis are caused by [H(+) ] rather than by [CO2 ]. The impaired HCO3 (-) uptake also provides a mechanistic explanation for lowered calcification under OA. Moreover, it explains the OA-dependent decrease in photosynthesis observed in high-light grown phytoplankton. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  10. Inorganic carbon loading as a primary driver of dissolved carbon dioxide concentrations in the lakes and reservoirs of the contiguous United States

    USGS Publications Warehouse

    McDonald, Cory P.; Stets, Edward; Striegl, Robert G.; Butman, David

    2013-01-01

    Accurate quantification of CO2 flux across the air-water interface and identification of the mechanisms driving CO2 concentrations in lakes and reservoirs is critical to integrating aquatic systems into large-scale carbon budgets, and to predicting the response of these systems to changes in climate or terrestrial carbon cycling. Large-scale estimates of the role of lakes and reservoirs in the carbon cycle, however, typically must rely on aggregation of spatially and temporally inconsistent data from disparate sources. We performed a spatially comprehensive analysis of CO2 concentration and air-water fluxes in lakes and reservoirs of the contiguous United States using large, consistent data sets, and modeled the relative contribution of inorganic and organic carbon loading to vertical CO2 fluxes. Approximately 70% of lakes and reservoirs are supersaturated with respect to the atmosphere during the summer (June–September). Although there is considerable interregional and intraregional variability, lakes and reservoirs represent a net source of CO2 to the atmosphere of approximately 40 Gg C d–1 during the summer. While in-lake CO2 concentrations correlate with indicators of in-lake net ecosystem productivity, virtually no relationship exists between dissolved organic carbon and pCO2,aq. Modeling suggests that hydrologic dissolved inorganic carbon supports pCO2,aq in most supersaturated systems (to the extent that 12% of supersaturated systems simultaneously exhibit positive net ecosystem productivity), and also supports primary production in most CO2-undersaturated systems. Dissolved inorganic carbon loading appears to be an important determinant of CO2concentrations and fluxes across the air-water interface in the majority of lakes and reservoirs in the contiguous United States.

  11. Carbon availability for the fungus triggers nitrogen uptake and transport in the arbuscular mycorrhizal symbiosis

    USDA-ARS?s Scientific Manuscript database

    The arbuscular mycorrhizal (AM) symbiosis is characterized by a transfer of nutrients in exchange for carbon. We tested the effect of the carbon availability for the AM fungus Glomus intraradices on nitrogen (N) uptake and transport in the symbiosis. We followed the uptake and transport of 15N and ...

  12. Bicarbonate uptake via an anion exchange protein is the main mechanism of inorganic carbon acquisition by the giant kelp Macrocystis pyrifera (Laminariales, Phaeophyceae) under variable pH.

    PubMed

    Fernández, Pamela A; Hurd, Catriona L; Roleda, Michael Y

    2014-12-01

    Macrocystis pyrifera is a widely distributed, highly productive, seaweed. It is known to use bicarbonate (HCO3 (-) ) from seawater in photosynthesis and the main mechanism of utilization is attributed to the external catalyzed dehydration of HCO3 (-) by the surface-bound enzyme carbonic anhydrase (CAext ). Here, we examined other putative HCO3 (-) uptake mechanisms in M. pyrifera under pHT 9.00 (HCO3 (-) : CO2  = 940:1) and pHT 7.65 (HCO3 (-) : CO2  = 51:1). Rates of photosynthesis, and internal CA (CAint ) and CAext activity were measured following the application of AZ which inhibits CAext , and DIDS which inhibits a different HCO3 (-) uptake system, via an anion exchange (AE) protein. We found that the main mechanism of HCO3 (-) uptake by M. pyrifera is via an AE protein, regardless of the HCO3 (-) : CO2 ratio, with CAext making little contribution. Inhibiting the AE protein led to a 55%-65% decrease in photosynthetic rates. Inhibiting both the AE protein and CAext at pHT 9.00 led to 80%-100% inhibition of photosynthesis, whereas at pHT 7.65, passive CO2 diffusion supported 33% of photosynthesis. CAint was active at pHT 7.65 and 9.00, and activity was always higher than CAext , because of its role in dehydrating HCO3 (-) to supply CO2 to RuBisCO. Interestingly, the main mechanism of HCO3 (-) uptake in M. pyrifera was different than that in other Laminariales studied (CAext -catalyzed reaction) and we suggest that species-specific knowledge of carbon uptake mechanisms is required in order to elucidate how seaweeds might respond to future changes in HCO3 (-) :CO2 due to ocean acidification. © 2014 Phycological Society of America.

  13. Organic and inorganic nitrogen uptake by 21 dominant tree species in temperate and tropical forests.

    PubMed

    Liu, Min; Li, Changcheng; Xu, Xingliang; Wanek, Wolfgang; Jiang, Ning; Wang, Huimin; Yang, Xiaodong

    2017-11-01

    Evidence shows that many tree species can take up organic nitrogen (N) in the form of free amino acids from soils, but few studies have been conducted to compare organic and inorganic N uptake patterns in temperate and tropical tree species in relation to mycorrhizal status and successional state. We labeled intact tree roots by brief 15N exposures using field hydroponic experiments in a temperate forest and a tropical forest in China. A total of 21 dominant tree species were investigated, 8 in the temperate forest and 13 in the tropical forest. All investigated tree species showed highest uptake rates for NH4+ (ammonium), followed by glycine and NO3- (nitrate). Uptake of NH4+ by temperate trees averaged 12.8 μg N g-1 dry weight (d.w.) root h-1, while those by tropical trees averaged 6.8 μg N g-1 d.w. root h-1. Glycine uptake rates averaged 3.1 μg N g-1 d.w. root h-1 for temperate trees and 2.4 μg N g-1 d.w. root h-1 for tropical trees. NO3- uptake was the lowest (averaging 0.8 μg N g-1 d.w. root h-1 for temperate trees and 1.2 μg N g-1 d.w. root h-1 for tropical trees). Uptake of NH4+ accounted for 76% of the total uptake of all three N forms in the temperate forest and 64% in the tropical forest. Temperate tree species had similar glycine uptake rates as tropical trees, with the contribution being slightly lower (20% in the temperate forest and 23% in the tropical forest). All tree species investigated in the temperate forest were ectomycorrhizal and all species but one in the tropical forest were arbuscular mycorrhizal (AM). Ectomycorrhizal trees showed significantly higher NH4+ and lower NO3- uptake rates than AM trees. Mycorrhizal colonization rates significantly affected uptake rates and contributions of NO3- or NH4+, but depended on forest types. We conclude that tree species in both temperate and tropical forests preferred to take up NH4+, with organic N as the second most important N source. These findings suggest that temperate and tropical forests

  14. Revised budget for the oceanic uptake of anthropogenic carbon dioxide

    USGS Publications Warehouse

    Sarmiento, J.L.; Sundquist, E.T.

    1992-01-01

    TRACER-CALIBRATED models of the total uptake of anthropogenic CO2 by the world's oceans give estimates of about 2 gigatonnes carbon per year1, significantly larger than a recent estimate2 of 0.3-0.8 Gt C yr-1 for the synoptic air-to-sea CO2 influx. Although both estimates require that the global CO2 budget must be balanced by a large unknown terrestrial sink, the latter estimate implies a much larger terrestrial sink, and challenges the ocean model calculations on which previous CO2 budgets were based. The discrepancy is due in part to the net flux of carbon to the ocean by rivers and rain, which must be added to the synoptic air-to-sea CO2 flux to obtain the total oceanic uptake of anthropogenic CO2. Here we estimate the magnitude of this correction and of several other recently proposed adjustments to the synoptic air-sea CO2 exchange. These combined adjustments minimize the apparent inconsistency, and restore estimates of the terrestrial sink to values implied by the modelled oceanic uptake.

  15. Neomycin inhibits PDGF-induced IP3 formation and DNA synthesis but not PDGF-stimulated uptake of inorganic phosphate in C3H/10T1/2 fibroblasts.

    PubMed

    Vassbotn, F S; Langeland, N; Holmsen, H

    1990-09-01

    Porcine PDGF was found to increase [3H]inositol trisphosphate, [3H]thymidine incorporation and 32P-labelling of polyphosphoinositides in C3H/10T1/2 Cl 8 fibroblasts. These responses to PDGF stimulation were all inhibited by 5 mM neomycin, a polycationic aminoglycoside formerly known to inhibit polyphosphoinositide turnover. PDGF also markedly increased the cellular uptake of inorganic [32P]Pi. This response of PDGF was not inhibited by neomycin (5 mM). Thus, neomycin inhibited PDGF-induced IP3 formation, 32P-labelling of polyphosphoinositides and DNA synthesis, but not cellular uptake of inorganic phosphate. These effects of neomycin suggest a bifurcation of the initial part of the PDGF-induced signal transduction, separating at the receptor level or before phospholipase C activation.

  16. Biological uptake of polychlorinated biphenyls by Macoma balthica from sediment amended with activated carbon

    USGS Publications Warehouse

    McLeod, Pamela B.; van den Heuvel-Greve, Martine J.; Luoma, S.N.; Luthy, R.G.

    2007-01-01

    This work characterizes the efficacy of activated carbon amendment in reducing polychlorinated biphenyl (PCB) bioavailability to clams (Macoma balthica) from field-contaminated sediment (Hunters Point Naval Shipyard, San Francisco Bay, CA, USA) Test methods were developed for the use of clams to investigate the effects of sediment amendment on biological uptake. Sediment was mixed with activated carbon for one month. Bioaccumulation tests (28 d) were employed to assess the relationships between carbon dose and carbon particle size on observed reductions in clam biological uptake of PCBs. Extraction and cleanup protocols were developed for the clam tissue. Efficacy of activated carbon treatment was found to increase with both increasing carbon dose and decreasing carbon particle size. Average reductions in bioaccumulation of 22, 64, and 84% relative to untreated Hunters Point sediment were observed for carbon amendments of 0.34, 1.7, and 3.4%, respectively. Average bioaccumulation reductions of 41, 73, and 89% were observed for amendments (dose = 1.7% dry wt) with carbon particles of 180 to 250, 75 to 180, and 25 to 75 ??m, respectively, in diameter, indicating kinetic phenomena in these tests. Additionally, a biodynamic model quantifying clam PCB uptake from water and sediment as well as loss through elimination provided a good fit of experimental data. Model predictions suggest that the sediment ingestion route contributed 80 to 95% of the PCB burdens in the clams. ?? 2007 SETAC.

  17. Carbon Uptake and Storage in Old-Growth and Second-Growth Forests in Central Vermont

    NASA Astrophysics Data System (ADS)

    Lloyd, A. H.; Weisser, O.

    2013-12-01

    Managing forests towards the goal of maximizing carbon uptake and storage provides an important tool for climate change mitigation. There is significant spatial and temporal variation among forests, even within an ecosystem type, in annual uptake and storage of carbon. Understanding the causes for that variation is important in refining management practices and restoration goals that promote carbon storage. We explore the variation in carbon storage and uptake among forests differing in age in central Vermont, comparing young, intermediate-aged, and old-growth forests. We generally expected that younger forests would have a higher annual uptake of carbon than older forests. Significant uncertainty exists, however, about the temporal trajectory from a young, rapidly growing forest to an old-growth forest that may be in a steady-state, with no net uptake of carbon. Within each forest, we compare differences among functional groups of species (e.g., hardwoods versus softwoods) in contribution to overall forest carbon uptake and storage. Our study sites include an old-growth hemlock/mixed hardwood forest that has not been directly affected by human activities, and which contains trees upwards of 350 years old; a 130-year-old mixed hardwood forest that has recolonized former pasture land; and a 90-year-old mixed hardwood forest on formerly agricultural floodplain land. Carbon storage in live and dead biomass pools was estimated from allometric equations, based on repeated measurements of tree diameters in permanently marked study plots. Historical patterns of carbon storage in living biomass were estimated by reconstructing tree diameter from measured increment cores, and then estimating the living biomass in each year. As expected, the old-growth forest stored almost twice the C in live biomass as the two second-growth forests, which stored equivalent amounts of carbon, despite the difference in age. Dead biomass was a larger pool of C in the old-growth forest than in

  18. Measurements of the dissolved inorganic carbon system and associated biogeochemical parameters in the Canadian Arctic, 1974-2009

    NASA Astrophysics Data System (ADS)

    Giesbrecht, K. E.; Miller, L. A.; Davelaar, M.; Zimmermann, S.; Carmack, E.; Johnson, W. K.; Macdonald, R. W.; McLaughlin, F.; Mucci, A.; Williams, W. J.; Wong, C. S.; Yamamoto-Kawai, M.

    2014-03-01

    We have assembled and conducted primary quality control on previously publicly unavailable water column measurements of the dissolved inorganic carbon system and associated biogeochemical parameters (oxygen, nutrients, etc.) made on 26 cruises in the subarctic and Arctic regions dating back to 1974. The measurements are primarily from the western side of the Canadian Arctic, but also include data that cover an area ranging from the North Pacific to the Gulf of St. Lawrence. The data were subjected to primary quality control (QC) to identify outliers and obvious errors. This data set incorporates over four thousand individual measurements of total inorganic carbon (TIC), alkalinity, and pH from the Canadian Arctic over a period of more than 30 years and provides an opportunity to increase our understanding of temporal changes in the inorganic carbon system in northern waters and the Arctic Ocean. The data set is available for download on the CDIAC (Carbon Dioxide Information Analysis Center) website: http://cdiac.ornl.gov/ftp/oceans/IOS_Arctic_Database/ (doi:10.3334/CDIAC/OTG.IOS_ARCT_CARBN).

  19. Simulated In Situ Determination of Soil Profile Organic and Inorganic Carbon With LIBS and VisNIR

    NASA Astrophysics Data System (ADS)

    Bricklemyer, R. S.; Brown, D. J.; Clegg, S. M.; Barefield, J. E.

    2008-12-01

    There is growing need for rapid, accurate, and inexpensive methods to measure, and verify soil organic carbon (SOC) change for national greenhouse gas accounting and the development of a soil carbon trading market. Laser Induced Breakdown Spectroscopy (LIBS) and Visible and Near Infrared Spectroscopy (VisNIR) are complementary analytical techniques that have the potential to fill that need. The LIBS method provides precise elemental analysis of soils, but generally cannot distinguish between organic C and inorganic C. VisNIR has been established as a viable technique for measuring soil properties including SOC and inorganic carbon (IC). As part of the Big Sky Carbon Sequestration Regional Partnership, 240 intact core samples (3.8 x 50 cm) have been collected from six agricultural fields in north central Montana, USA. Each of these core samples were probed concurrently with LIBS and VisNIR at 2.5, 7.5, 12.5, 17.5, 22.5, 27.5, 35 and 45 cm (+/- 1.5 cm) depths. VisNIR measurements were taken using an Analytical Spectral Devices (ASD, Boulder, CO, USA) Agrispec spectrometer to determine the partition of SOC vs. IC in the samples. The LIBS scans were collected with the LANL LIBS Core Scanner Instrument which collected the entire 200 - 900 nm plasma emission including the 247.8 nm carbon emission line. This instrument also collected the emission from the elements typically found in inorganic carbon (Ca and Mg) and organic carbon (H, O, and N). Subsamples of soil (~ 4 g) were taken from interrogation points for laboratory determination of SOC and IC. Using this analytical data, we constructed several full spectrum multivariate VisNIR/LIBS calibration models for SOC and IC. These models were then applied to independent validation cores for model evaluation.

  20. Fluxes of inorganic carbon from two forested catchments in the Appalachian mountains

    Treesearch

    Fred Worrall; Wayne T. Swank; Tim Burt

    2005-01-01

    This study uses long-term records of stream chemistry, discharge and air temperature from two neighbouring forested catchments in the southern Appalachians in order to calculate production of dissolved C02 and dissolved inorganic carbon (DIC). One of the pair of catchments was clear-felled during the period of the study. The study shows that: (1...

  1. Inorganic Carbon Turnover caused by Digestion of Carbonate Sands and Metabolic Activity of Holothurians

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schneider, Kenneth; Silverman, Jacob; Kravitz, Benjamin S.

    Recent measurements have shown that holothurians (sea cucumbers) play an important role in the cycling of CaCO3 in tropical coral reef systems through ingestion and processing of carbonate sediment. In this study inorganic additional aspects of carbon turnover were determined in laboratory incubations of Holothuria atra, H. leucospilota and Stichopus herrmanni from One Tree Reef, Great Barrier Reef. The pH values of the gut lumen ranged from 6.1 to 6.7 in animals with empty digestive tracts as opposed to 7.0 to 7.6 when digestive tracts were filled with sediment. Empty gut volume estimates for H. atra and S. herrmanni weremore » 36 ± 4 mL and 151 ± 14 mL, respectively. Based on these measurements it is estimated that these species process 19 ± 2kg and 80 ± 7kg CaCO3 sand yr-1 per individual, respectively. The annual dissolution rates of H. atra and S. herrmanni of 6.5±1.9g and 9.6±1.4g, respectively, suggest that 0.05±0.02% and 0.1±0.02% of the CaCO3 processed through their gut annually is dissolved. During the incubations the CaCO3 dissolution was 0.07±0.01%, 0.04±0.01% and 0.21±0.05% of the fecal casts for H. atra, H. leucospilota and S. herrmanni, respectively. The CaCO3 saturation state for both aragonite and calcite minerals during laboratory incubations decreased markedly due to a greater increase in dissolved inorganic carbon (DIC) relative to total alkalinity (AT) as a result of respiration by the animals. Our results support the hypothesis that deposit feeders such as sea cucumbers play an important ecological role in the coral reef CaCO3 cycle.« less

  2. Influences of terrestrial inorganic carbon on carbonate system in China Seas and the implication for China Seas' vulnerabilities to potentially negative effects of ocean acidification

    NASA Astrophysics Data System (ADS)

    Guo, X.; Zhai, W. D.; Guo, L. G.; Jiang, Z. P.; Qi, D.; Xu, Y.; Huang, X.

    2017-12-01

    We investigated sea surface carbonate system and ancillary parameters in the northern South China Sea (SCS), East China Sea (ECS), Yellow Sea, and Bohai Sea during a single cruise from late April to June 2011. In this transitional season between the dry/cold and wet/warm seasons, we observed ubiquitous terrestrial inorganic carbon signals in the Yellow Sea and Bohai Sea, as indicated by excess total alkalinity (TAlk) from 150 to 450 μmol kg-1 and excess Ca concentrations from 100 to 470 μmol kg-1, associated with relatively high DIC/TAlk ratios from 0.88 to 0.92. In contrast, these terrestrial inorganic carbon signals were limited to nearshore areas in the southern ECS and northern SCS. These results suggested that the Yellow Sea and Bohai Sea were dominated by terrestrial inputs all over the year, while the terrestrial signals in the southern ECS and northern SCS were highly diminished in dry seasons through water mixing with open ocean waters (likely introduced by Kuroshio). This study also showed that the terrestrial inorganic carbon inputs had diminished carbonate ion concentrations and CaCO3 saturation states in the Yellow Sea and Bohai Sea. This may contribute to recent findings that the North Yellow Sea represents one of the systems in the China seas most vulnerable to the potentially negative effects of ocean acidification.

  3. Sensitivity Analysis Tailored to Constrain 21st Century Terrestrial Carbon-Uptake

    NASA Astrophysics Data System (ADS)

    Muller, S. J.; Gerber, S.

    2013-12-01

    The long-term fate of terrestrial carbon (C) in response to climate change remains a dominant source of uncertainty in Earth-system model projections. Increasing atmospheric CO2 could be mitigated by long-term net uptake of C, through processes such as increased plant productivity due to "CO2-fertilization". Conversely, atmospheric conditions could be exacerbated by long-term net release of C, through processes such as increased decomposition due to higher temperatures. This balance is an important area of study, and a major source of uncertainty in long-term (>year 2050) projections of planetary response to climate change. We present results from an innovative application of sensitivity analysis to LM3V, a dynamic global vegetation model (DGVM), intended to identify observed/observable variables that are useful for constraining long-term projections of C-uptake. We analyzed the sensitivity of cumulative C-uptake by 2100, as modeled by LM3V in response to IPCC AR4 scenario climate data (1860-2100), to perturbations in over 50 model parameters. We concurrently analyzed the sensitivity of over 100 observable model variables, during the extant record period (1970-2010), to the same parameter changes. By correlating the sensitivities of observable variables with the sensitivity of long-term C-uptake we identified model calibration variables that would also constrain long-term C-uptake projections. LM3V employs a coupled carbon-nitrogen cycle to account for N-limitation, and we find that N-related variables have an important role to play in constraining long-term C-uptake. This work has implications for prioritizing field campaigns to collect global data that can help reduce uncertainties in the long-term land-atmosphere C-balance. Though results of this study are specific to LM3V, the processes that characterize this model are not completely divorced from other DGVMs (or reality), and our approach provides valuable insights into how data can be leveraged to be better

  4. Methodologies for extraction of dissolved inorganic carbon for stable carbon isotope studies : evaluation and alternatives

    USGS Publications Warehouse

    Hassan, Afifa Afifi

    1982-01-01

    The gas evolution and the strontium carbonate precipitation techniques to extract dissolved inorganic carbon (DIC) for stable carbon isotope analysis were investigated. Theoretical considerations, involving thermodynamic calculations and computer simulation pointed out several possible sources of error in delta carbon-13 measurements of the DIC and demonstrated the need for experimental evaluation of the magnitude of the error. An alternative analytical technique, equilibration with out-gassed vapor phase, is proposed. The experimental studies revealed that delta carbon-13 of the DIC extracted from a 0.01 molar NaHC03 solution by both techniques agreed within 0.1 per mil with the delta carbon-13 of the DIC extracted by the precipitation technique, and an increase of only 0.27 per mil in that extracted by the gas evolution technique. The efficiency of extraction of DIC decreased with sulfate concentration in the precipitation technique but was independent of sulfate concentration in the gas evolution technique. Both the precipitation and gas evolution technique were found to be satisfactory for extraction of DIC from different kinds of natural water for stable carbon isotope analysis, provided appropriate precautions are observed in handling the samples. For example, it was found that diffusion of atmospheric carbon dioxide does alter the delta carbon-13 of the samples contained in polyethylene bottles; filtration and drying in the air change the delta carbon-13 of the samples contained in polyethylene bottles; filtration and drying in the air change the delta carbon-13 of the precipitation technique; hot manganese dioxide purification changes the delta carbon-13 of carbon dioxide. (USGS)

  5. Combining multiple ecosystem productivity measurements to constrain carbon uptake estimates in semiarid grasslands and shrublands

    NASA Astrophysics Data System (ADS)

    Maurer, G. E.; Krofcheck, D. J.; Collins, S. L.; Litvak, M. E.

    2016-12-01

    Recent observational and modeling studies have indicated that semiarid ecosystems are more dynamic contributors to the global carbon budget than once thought. Semiarid carbon fluxes, however, are generally small, with high interannual and spatial variability, which suggests that validating their global significance may depend on examining multiple productivity measures and their associated uncertainties and inconsistencies. We examined ecosystem productivity from eddy covariance (NEE), harvest (NPP), and terrestrial biome models (NEPm) at two very similar grassland sites and one creosote shrubland site in the Sevilleta National Wildlife Refuge of central New Mexico, USA. Our goal was to assess site and methodological correspondence in annual carbon uptake, patterns of interannual variability, and measurement uncertainty. One grassland site was a perennial carbon source losing 30 g C m-2 per year on average, while the other two sites were carbon sources or sinks depending on the year, with average net uptake of 5 and 25 g C m-2 per year at the grassland and shrubland site, respectively. Uncertainty values for cumulative annual NEE overlapped between the three sites in most years. When combined, aboveground and belowground annual NPP measurements were 15% higher than annual NEE values and did not confirm a loss of carbon at any site in any year. Despite differences in mean site carbon balance, year-to-year changes in cumulative annual NEE and NPP were similar at all sites with years 2010 and 2013 being favorable for carbon uptake and 2011 and 2012 being unfavorable at all sites. Modeled NEPm data for a number of nearby grid cells reproduced only a fraction of the observed range in carbon uptake and its interannual variability. These three sites are highly similar in location and climate and multiple carbon flux measurements confirm the high interannual variability in carbon flux. The exact magnitude of these fluxes, however, remains difficult to discern.

  6. Synergy of rising nitrogen depositions and atmospheric CO2 on land carbon uptake moderately offsets global warming

    NASA Astrophysics Data System (ADS)

    Churkina, Galina; Brovkin, Victor; von Bloh, Werner; Trusilova, Kristina; Jung, Martin; Dentener, Frank

    2009-12-01

    Increased carbon uptake of land in response to elevated atmospheric CO2 concentration and nitrogen deposition could slow down the rate of CO2 increase and facilitate climate change mitigation. Using a coupled model of climate, ocean, and land biogeochemistry, we show that atmospheric nitrogen deposition and atmospheric CO2 have a strong synergistic effect on the carbon uptake of land. Our best estimate of the global land carbon uptake in the 1990s is 1.34 PgC/yr. The synergistic effect could explain 47% of this carbon uptake, which is higher than either the effect of increasing nitrogen deposition (29%) or CO2 fertilization (24%). By 2030, rising carbon uptake on land has a potential to reduce atmospheric CO2 concentration by about 41 ppm out of which 16 ppm reduction would come from the synergetic response of land to the CO2 and nitrogen fertilization effects. The strength of the synergy depends largely on the cooccurrence of high nitrogen deposition regions with nonagricultural ecosystems. Our study suggests that reforestation and sensible ecosystem management in industrialized regions may have larger potential for climate change mitigation than anticipated.

  7. Stable carbon isotopes of dissolved inorganic carbon for a zonal transect across the subpolar North Atlantic Ocean in summer 2014

    NASA Astrophysics Data System (ADS)

    Humphreys, Matthew P.; Greatrix, Florence M.; Tynan, Eithne; Achterberg, Eric P.; Griffiths, Alex M.; Fry, Claudia H.; Garley, Rebecca; McDonald, Alison; Boyce, Adrian J.

    2016-06-01

    The stable carbon isotope composition of dissolved inorganic carbon (δ13CDIC) in seawater was measured in samples collected during June-July 2014 in the subpolar North Atlantic. Sample collection was carried out on the RRS James Clark Ross cruise JR302, part of the "Radiatively Active Gases from the North Atlantic Region and Climate Change" (RAGNARoCC) research programme. The observed δ13CDIC values for cruise JR302 fall in a range from -0.07 to +1.95 ‰, relative to the Vienna Pee Dee Belemnite standard. From duplicate samples collected during the cruise, the 1σ precision for the 341 results is 0.08 ‰, which is similar to our previous work and other studies of this kind. We also performed a cross-over analysis using nearby historical δ13CDIC data, which indicated that there were no significant systematic offsets between our measurements and previously published results. We also included seawater reference material (RM) produced by A. G. Dickson (Scripps Institution of Oceanography, USA) in every batch of analysis, enabling us to improve upon the calibration and quality-control procedures from a previous study. The δ13CDIC is consistent within each RM batch, although its value is not certified. We report δ13CDIC values of 1.15 ± 0.03 ‰ and 1.27 ± 0.05 ‰ for batches 141 and 144 respectively. Our JR302 δ13CDIC data can be used - along with measurements of other biogeochemical variables - to constrain the processes that control DIC in the interior ocean, in particular the oceanic uptake of anthropogenic carbon dioxide and the biological carbon pump. Our δ13CDIC results are available from the British Oceanographic Data Centre - doi:10.5285/22235f1a-b7f3-687f-e053-6c86abc0c8a6.

  8. Coral Uptake of Inorganic Phosphorus and Nitrogen Negatively Affected by Simultaneous Changes in Temperature and pH

    PubMed Central

    Godinot, Claire; Houlbrèque, Fanny

    2011-01-01

    The effects of ocean acidification and elevated seawater temperature on coral calcification and photosynthesis have been extensively investigated over the last two decades, whereas they are still unknown on nutrient uptake, despite their importance for coral energetics. We therefore studied the separate and combined impacts of increases in temperature and pCO2 on phosphate, ammonium, and nitrate uptake rates by the scleractinian coral S. pistillata. Three experiments were performed, during 10 days i) at three pHT conditions (8.1, 7.8, and 7.5) and normal temperature (26°C), ii) at three temperature conditions (26°, 29°C, and 33°C) and normal pHT (8.1), and iii) at three pHT conditions (8.1, 7.8, and 7.5) and elevated temperature (33°C). After 10 days of incubation, corals had not bleached, as protein, chlorophyll, and zooxanthellae contents were the same in all treatments. However, photosynthetic rates significantly decreased at 33°C, and were further reduced for the pHT 7.5. The photosynthetic efficiency of PSII was only decreased by elevated temperature. Nutrient uptake rates were not affected by a change in pH alone. Conversely, elevated temperature (33°C) alone induced an increase in phosphate uptake but a severe decrease in nitrate and ammonium uptake rates, even leading to a release of nitrogen into seawater. Combination of high temperature (33°C) and low pHT (7.5) resulted in a significant decrease in phosphate and nitrate uptake rates compared to control corals (26°C, pHT = 8.1). These results indicate that both inorganic nitrogen and phosphorus metabolism may be negatively affected by the cumulative effects of ocean warming and acidification. PMID:21949839

  9. Estimating the carbon budget and maximizing future carbon uptake for a temperate forest region in the U.S.

    PubMed Central

    2012-01-01

    Background Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and industrial forest carbon cycles are rarely studied in a whole-system structure. The forest system carbon balance is the difference between the biological (net ecosystem production) and industrial (net emissions from forest industry) forest carbon cycles, but to date this critical whole system analysis is lacking. This study presents a model of the forest system, uses it to compute the carbon balance, and outlines a methodology to maximize future carbon uptake in a managed forest region. Results We used a coupled forest ecosystem process and forest products life cycle inventory model for a regional temperate forest in the Midwestern U.S., and found the net system carbon balance for this 615,000 ha forest was positive (2.29 t C ha-1 yr-1). The industrial carbon budget was typically less than 10% of the biological system annually, and averaged averaged 0.082 t C ha-1 yr-1. Net C uptake over the next 100-years increased by 22% or 0.33 t C ha-1 yr-1 relative to the current harvest rate in the study region under the optized harvest regime. Conclusions The forest’s biological ecosystem current and future carbon uptake capacity is largely determined by forest harvest practices that occurred over a century ago, but we show an optimized harvesting strategy would increase future carbon sequestration, or wood production, by 20-30%, reduce long transportation chain emissions, and maintain many desirable stand structural attributes that are correlated to biodiversity. Our results for this forest region suggest that increasing harvest over the next 100 years increases the strength of

  10. Diversity of freshwater Epsilonproteobacteria and dark inorganic carbon fixation in the sulphidic redoxcline of a meromictic karstic lake.

    PubMed

    Noguerola, Imma; Picazo, Antonio; Llirós, Marc; Camacho, Antonio; Borrego, Carles M

    2015-07-01

    Sulfidic redoxclines are a suitable niche for the growth and activity of different chemo- and photolithotrophic sulphide-oxidizing microbial groups such as the Epsilonproteobacteria and the green sulfur bacteria (GSB). We have investigated the diversity, abundance and contribution to inorganic carbon uptake of Epsilonproteobacteria in a meromictic basin of Lake Banyoles. CARD-FISH counts revealed that Epsilonproteobacteria were prevalent at the redoxcline in winter (maximum abundance of 2 × 10(6) cells mL(-1), ≈60% of total cells) but they were nearly absent in summer, when GSB bloomed. This seasonal trend was supported by 16S rRNA gene pyrotag datasets, which revealed that the epsilonproteobacterial community was mainly composed of a member of the genus Arcobacter. In situ incubations using NaH(14)CO3 and MAR-CARD-FISH observations showed that this population assimilated CO2 in the dark, likely being mainly responsible for the autotrophic activity at the redoxcline in winter. Clone libraries targeting the aclB gene provided additional evidence of the potential capacity of these epsilonproteobacteria to fix carbon via rTCA cycle. Our data reinforce the key role of Epsilonproteobacteria in linking carbon and sulphur cycles, extend their influence to freshwater karstic lakes and raise questions about the actual contribution of chemolithotrophy at their redoxcline and euxinic water compartments. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes

    NASA Astrophysics Data System (ADS)

    Morales-Williams, Ana M.; Wanamaker, Alan D., Jr.; Downing, John A.

    2017-06-01

    Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3-) across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs). To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC) and phytoplankton particulate organic carbon (δ13Cphyto) in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass-balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3- during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3- uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

  12. Carbon Balance in an Irrigated Corn Field after Inorganic Fertilizer or Manure Application

    NASA Astrophysics Data System (ADS)

    Lentz, R. D.; Lehrsch, G. A.

    2014-12-01

    Little is known about inorganic fertilizer or manure effects on organic carbon (OC) and inorganic C (IC) losses from a furrow irrigated field, particularly in the context of other system C gains or losses. In 2003 and 2004, we measured dissolved organic and inorganic C (DOC, DIC), particulate OC and IC (POC, PIC) concentrations in irrigation inflow, runoff, and percolation waters (6-7 irrigations/y); C inputs from soil amendments and crop biomass; harvested C; and gaseous C emissions from field plots cropped to silage corn (Zea mays L.) in southern Idaho. Annual treatments included: (M) 13 (y 1) and 34 Mg/ha (y 2) stockpiled dairy manure; (F) 78 (yr 1) and 195 kg N/ha (y 2) inorganic N fertilizer; or (NA) no amendment--control. The mean annual total C input into M plots averaged 16.1 Mg/ha, 1.4-times greater than that for NA (11.5 Mg/ha) or F (11.1 Mg/ha), while total C outputs for the three treatments were similar, averaging 11.8 Mg/ha. Thus, the manure plots ended each growing season with an average net gain of 3.8 Mg C/ha (a positive net C flux), while the control (-0.5 Mg C/ha) and fertilizer (-0.4 Mg C/ha) treatments finished the season with a net C loss. Atmospheric CO2 incorporated into the crop biomass contributed 96% of the mean annual C input to NA and F plots but only 68% to M plots. We conclude that nutrient amendments substantially influence the short-term carbon balance of our furrow-irrigated system. Amendments had both direct and indirect influences on individual C components, such as the losses of DIC and POC in runoff and DOC in percolation water, producing temporally complex outcomes which may depend on environmental conditions external to the field.

  13. Watershed scale spatial variability in dissolved and total organic and inorganic carbon in contrasting UK catchments

    NASA Astrophysics Data System (ADS)

    Cumberland, S.; Baker, A.; Hudson, N. J.

    2006-12-01

    Approximately 800 organic and inorganic carbon analyses have been undertaken from watershed scale and regional scale spatial surveys in various British catchments. These include (1) a small (<100 sq-km) urban catchment (Ouseburn, N England); (2) a headwater, lowland agricultural catchment (River Tern, C England) (3) a large UK catchment (River Tyne, ~3000 sq-km) and (4) a spatial survey of ~300 analyses from rivers from SW England (~1700 sq-km). Results demonstrate that: (1) the majority of organic and inorganic carbon is in the dissolved (DOC and DIC) fractions; (2) that with the exception of peat rich headwaters, DIC concentration is always greater than DOC; (3) In the rural River Tern, riverine DOC and DIC are shown to follow a simple end- member mixing between DIC (DOC) rich (poor) ground waters and DOC (DIC) rich (poor) riparian wetlands for all sample sites. (4) In the urbanized Ouseburn catchment, although many sample sites also show this same mixing trend, some tributaries follow a pollutant trend of simultaneous increases in both DOC and DIC. The Ouseburn is part of the larger Tyne catchment: this larger catchment follows the simple groundwater DIC- soil water DOC end member mixing model, with the exception of the urban catchments which exhibit an elevated DIC compared to rural sites. (5) Urbanization is demonstrated to increase DIC compared to equivalent rural catchments; this DIC has potential sources including diffuse source inputs from the dissolution of concrete, point sources such as trade effluents and landfill leachates, and bedrock derived carbonates relocated to the soil dissolution zone by urban development. (6) DIC in rural SW England demonstrates that spatial variability in DIC can be attributed to variations in geology; but that DIC concentrations in the SW England rivers dataset are typically lower than the urbanized Tyne catchments despite the presence of carbonate bedrock in many of the sample catchments in the SW England dataset. (7

  14. Modelling the 13C and 12C isotopes of inorganic and organic carbon in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Gustafsson, Erik; Mörth, Carl-Magnus; Humborg, Christoph; Gustafsson, Bo G.

    2015-08-01

    In this study, 12C and 13C contents of all carbon containing state variables (dissolved inorganic and organic carbon, detrital carbon, and the carbon content of autotrophs and heterotrophs) have for the first time been explicitly included in a coupled physical-biogeochemical Baltic Sea model. Different processes in the carbon cycling have distinct fractionation values, resulting in specific isotopic fingerprints. Thus, in addition to simulating concentrations of different tracers, our new model formulation improves the possibility to constrain the rates of processes such as CO2 assimilation, mineralization, and air-sea exchange. We demonstrate that phytoplankton production and respiration, and the related air-sea CO2 fluxes, are to a large degree controlling the isotopic composition of organic and inorganic carbon in the system. The isotopic composition is further, but to a lesser extent, influenced by river loads and deep water inflows as well as transformation of terrestrial organic carbon within the system. Changes in the isotopic composition over the 20th century have been dominated by two processes - the preferential release of 12C to the atmosphere in association with fossil fuel burning, and the eutrophication of the Baltic Sea related to increased nutrient loads under the second half of the century.

  15. Inorganic markers, carbonaceous components and stable carbon isotope from biomass burning aerosols in northeast China

    NASA Astrophysics Data System (ADS)

    Cao, F.; Zhang, Y.; Kawamura, K.

    2015-12-01

    To better characterize the sources of fine particulate matter (i.e. PM2.5) in Sanjiang Plain, Northeast China, aerosol chemical composition such total carbon (TC), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and inorganic ions were studied as well as stable carbon isotopic composition (δ13C) of TC. Intensively open biomass burning episodes were identified from late September to early October by satellite fire and aerosol optical depth maps. During the biomass burning episodes, concentrations of PM2.5, OC, EC, and WSOC increased by a factor of 4-12 compared to non-biomass-burning periods. Non-sea-salt potassium is strongly correlated with PM2.5, OC, EC and WSOC, suggesting an important contribution of biomass burning emission. The enrichment in both the non-sea-salt potassium and chlorine is significantly larger than other inorganic species, indicating that biomass burning aerosols in Sanjiang Plain is mostly fresh and less aged. In addition, WSOC to OC ratio is relatively lower compared to that reported in biomass burning aerosols in tropical regions, supporting that biomass burning aerosols in Sanjiang Plain is mostly primary and secondary organic aerosols is not significant. A lower average δ13C value (-26.2‰) is found for the biomass-burning aerosols, suggesting a dominant contribution from combustion of C3 plants in the studied region.

  16. Nitrogen feedbacks increase future terrestrial ecosystem carbon uptake in an individual-based dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Wårlind, D.; Smith, B.; Hickler, T.; Arneth, A.

    2014-01-01

    Recently a considerable amount of effort has been put into quantifying how interactions of the carbon and nitrogen cycle affect future terrestrial carbon sinks. Dynamic vegetation models, representing the nitrogen cycle with varying degree of complexity, have shown diverging constraints of nitrogen dynamics on future carbon sequestration. In this study, we use the dynamic vegetation model LPJ-GUESS to evaluate how population dynamics and resource competition between plant functional types, combined with nitrogen dynamics, have influenced the terrestrial carbon storage in the past and to investigate how terrestrial carbon and nitrogen dynamics might change in the future (1850 to 2100; one exemplary "business-as-usual" climate scenario). Single factor model experiments of CO2 fertilisation and climate change show generally similar directions of the responses of C-N interactions, compared to the C-only version of the model, as documented in previous studies. Under a RCP 8.5 scenario, nitrogen limitation suppresses potential CO2 fertilisation, reducing the cumulative net ecosystem carbon uptake between 1850 and 2100 by 61%, and soil warming-induced increase in nitrogen mineralisation reduces terrestrial carbon loss by 31%. When environmental changes are considered conjointly, carbon sequestration is limited by nitrogen dynamics until present. However, during the 21st century nitrogen dynamics induce a net increase in carbon sequestration, resulting in an overall larger carbon uptake of 17% over the full period. This contradicts earlier model results that showed an 8 to 37% decrease in carbon uptake, questioning the often stated assumption that projections of future terrestrial C dynamics from C-only models are too optimistic.

  17. Linkages Between Terrestrial Carbon Uptake and Interannual Climate Variability over the Texas-northern Mexico High Plains

    NASA Astrophysics Data System (ADS)

    Parazoo, N.; Barnes, E. A.; Worden, J.; Harper, A. B.; Bowman, K. W.; Frankenberg, C.

    2014-12-01

    The Texas-northern Mexico high plains experienced record drought conditions in 2011 during strong negative phases of ENSO and the NAO. Given predictions of increased frequency and severity of drought under projected climate change [e.g., Reichstein et al., 2013] and recent findings of CO2 growth rate sensitivity to interannual variability of carbon uptake in semi-arid ecosystems [Poulter et al., 2014], we investigate the response of carbon uptake in the Texas high plains to interannual climate variability with the goal of improved mechanistic understanding of climate-carbon cycle links. Specifically, we examine (1) observed tendencies in regional scale carbon uptake and soil moisture from 2010 to 2011 using satellite observations of gross primary production (GPP) (from plant fluorescence) from GOSAT and soil moisture from SMOS, and (2) the interannual relationship between GPP and ENSO & NAO variability using terrestrial biosphere simulations from 1950-2012. Observations reveal widespread decline of GPP in 2011 (0.42 +/- 0.04 Pg C yr-1) correlated with negative soil moisture tendencies (r = 0.85 +/- 0.21) which leads to corresponding declines in net carbon uptake and transpiration (according to model simulations). Further examination of model results over the period 1950-2012 indicates that negative GPP anomalies are linked systematically to winter and spring precipitation deficits associated with overlapping negative phases of winter NAO and ENSO, with increasing magnitude of negative anomalies in strong La Niña years. Furthermore, the strongest decline of GPP, carbon uptake, and transpiration on record occurred during the 2011 drought and were associated with extreme negative phases of ENSO and NAO, with 2011 being the only year since 1950 that both indices exceeded 1 σ standard deviation.

  18. THE EFFECT OF PH AND DISSOLVED INORGANIC CARBON ON THE PROPERTIES OF IRON COLLOIDAL SUSPENSIONS

    EPA Science Inventory

    Discolored water resulting from suspended iron particles is a relatively common drinking water consumer complaint. These particles result from the oxygenation of Fe(II), and this study shows that pH and dissolved inorganic carbon (DIC) have important effects on their properties....

  19. Ocean Heat and Carbon Uptake in Transient Climate Change: Identifying Model Uncertainty

    NASA Technical Reports Server (NTRS)

    Romanou, Anastasia; Marshall, John

    2015-01-01

    Global warming on decadal and centennial timescales is mediated and ameliorated by the oceansequestering heat and carbon into its interior. Transient climate change is a function of the efficiency by whichanthropogenic heat and carbon are transported away from the surface into the ocean interior (Hansen et al. 1985).Gregory and Mitchell (1997) and Raper et al. (2002) were the first to identify the importance of the ocean heat uptakeefficiency in transient climate change. Observational estimates (Schwartz 2012) and inferences from coupledatmosphere-ocean general circulation models (AOGCMs; Gregory and Forster 2008; Marotzke et al. 2015), suggest thatocean heat uptake efficiency on decadal timescales lies in the range 0.5-1.5 W/sq m/K and is thus comparable to theclimate feedback parameter (Murphy et al. 2009). Moreover, the ocean not only plays a key role in setting the timing ofwarming but also its regional patterns (Marshall et al. 2014), which is crucial to our understanding of regional climate,carbon and heat uptake, and sea-level change. This short communication is based on a presentation given by A.Romanou at a recent workshop, Oceans Carbon and Heat Uptake: Uncertainties and Metrics, co-hosted by US CLIVARand OCB. As briefly reviewed below, we have incomplete but growing knowledge of how ocean models used in climatechange projections sequester heat and carbon into the interior. To understand and thence reduce errors and biases inthe ocean component of coupled models, as well as elucidate the key mechanisms at work, in the final section we outlinea proposed model intercomparison project named FAFMIP. In FAFMIP, coupled integrations would be carried out withprescribed overrides of wind stress and freshwater and heat fluxes acting at the sea surface.

  20. Dissolved inorganic carbon isotopic composition of the Gulf of Mexico deep-water masses.

    NASA Astrophysics Data System (ADS)

    Quintanilla-Terminel, J. G.; Herguera, J. C.; Ferreira-Bartrina, V.; Hernández-Ayón, J. M.; Camacho-Ibar, V.

    2014-12-01

    This study provides new data for the establishment of a carbon biogeochemical dynamics baseline in the deep Gulf of Mexico (GM) based on carbon isotopes in dissolved inorganic carbon. Water samples from 40 deep-water stations south of 25˚N were collected during XIXIMI-2 cruise, July 2011, aboard BO/Justo Sierra. Vertical profiles of temperature, salinity and dissolved oxygen (DO) were further measured in each station. In the Stable Isotopes Laboratory at CICESE we determined the carbon isotopic composition of the dissolved inorganic carbon (DIC) (δ13CDIC). Remarkably, density, DO and δ13CCID profiles showed a clear difference between the Loop current and the deep-waters of the GM south of 25˚N. We found the following average δ13CCID values in the Loop current and in the deep-waters of the Gulf: subtropical underwater (SUW): 0.73±0.06‰ and 0.86±0.04‰; 18 degree water (18W): 0.76 ± 0.08‰ and 0.58± 0.06‰; North Atlantic central water (NACW): 0.77 ± 0.05‰ and 0.71 ± 0.09‰; South Atlantic central water (SACW): 0.80 ± 0.08‰ and 0.77 ± 0.07‰; Antartic intermediate water (AAIW): 1.00 ± 0.06‰ and 0.90 ± 0.08‰; North Atlantic deep water (NADW): 1.03 ± 0.06‰ and 1.01 ± 0.10‰. We will discuss how the biological component, δ13CCID-BIO, of subsurface water masses match very closely the apparent oxygen utilization relation described by Kroopnick, 1985, with the exception of SUW, and as a consequence the 18W is probably the water mass most affected by organic carbon remineralization processes in the GM south of 25˚N. We further show how these waters seem to store a larger proportion of anthropogenic carbon than the deeper water masses.

  1. Soil calcium significantly promotes uptake of inorganic arsenic by garland chrysanthemum (ChrysanthemumL coronarium) fertilized with chicken manure bearing roxarsone and its metabolites.

    PubMed

    Yao, Lixian; Huang, Lianxi; Bai, Cuihua; He, Zhaohuan; Zhou, Changmin

    2017-07-01

    Roxarsone (ROX), a widely used feed organoarsenic additive, occurs as itself and its metabolites in animal manure that is commonly land used as fertilizer. Soil property impacts arsenic (As) speciation and bioavailability. Fourteen soils across China were used to conduct culture experiments to investigate As uptake by garland chrysanthemum (ChrysanthemumL coronarium), with the soils fertilized with chicken manure bearing ROX and its metabolites. The results show As(III) was the sole As form in garland chrysanthemum shoots, and As(III) and As(V) occurred in roots. Only inorganic As was detected in all soils when the plants were harvested. Stepwise regression analysis shows soil-exchangeable Ca predominated shoot As(III) concentration (shoot As(III) = 1.60030 soil Ca, R 2  = 0.8832***). Therefore, ROX is transferred into the human food chain finally as inorganic As in plants. Application of animal manure bearing ROX and its metabolites is not recommended in Ca-rich soils to avoid excess inorganic As dietary exposure.

  2. Seasonal variability of the inorganic carbon system in a large coastal plain estuary

    NASA Astrophysics Data System (ADS)

    Joesoef, Andrew; Kirchman, David L.; Sommerfield, Christopher K.; Cai, Wei-Jun

    2017-11-01

    Carbonate geochemistry research in large estuarine systems is limited. More work is needed to understand how changes in land-use activity influence watershed export of organic and inorganic carbon, acids, and nutrients to the coastal ocean. To investigate the seasonal variation of the inorganic carbon system in the Delaware Estuary, one of the largest estuaries along the US east coast, dissolved inorganic carbon (DIC), total alkalinity (TA), and pH were measured along the estuary from June 2013 to April 2015. In addition, DIC, TA, and pH were periodically measured from March to October 2015 in the nontidal freshwater Delaware, Schuylkill, and Christina rivers over a range of discharge conditions. There were strong negative relationships between river TA and discharge, suggesting that changes in HCO3- concentrations reflect dilution of weathering products in the drainage basin. The ratio of DIC to TA, an understudied but important property, was high (1.11) during high discharge and low (0.94) during low discharge, reflecting additional DIC input in the form of carbon dioxide (CO2), most likely from terrestrial organic matter decomposition, rather than bicarbonate (HCO3-) inputs due to drainage basin weathering processes. This is also a result of CO2 loss to the atmosphere due to rapid water transit during the wet season. Our data further show that elevated DIC in the Schuylkill River is substantially different than that in the Delaware River. Thus, tributary contributions must be considered when attributing estuarine DIC sources to the internal carbon cycle versus external processes such as drainage basin mineralogy, weathering intensity, and discharge patterns. Long-term records in the Delaware and Schuylkill rivers indicate shifts toward higher alkalinity in estuarine waters over time, as has been found in other estuaries worldwide. Annual DIC input flux to the estuary and export flux to the coastal ocean are estimated to be 15.7 ± 8.2 × 109 mol C yr-1 and 16

  3. Inorganic markers, carbonaceous components and stable carbon isotope from biomass burning aerosols in Northeast China.

    PubMed

    Cao, Fang; Zhang, Shi-Chun; Kawamura, Kimitaka; Zhang, Yan-Lin

    2016-12-01

    To better characterize the chemical compositions and sources of fine particulate matter (i.e. PM 2.5 ) in Sanjiang Plain, Northeast China, total carbon (TC), organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and inorganic ions as well as stable carbon isotopic composition (δ 13 C) were measured in this study. Intensively open biomass burning episodes are identified from late September to early October by satellite fire and aerosol optical depth maps. During the biomass-burning episode, concentrations of PM 2.5 , OC, EC, and WSOC are increased by a factor of 4-12 compared to those during the non-biomass-burning period. Non-sea-salt potassium is strongly correlated with PM 2.5 , OC, EC and WSOC, demonstrating an important contribution from biomass-burning emissions. The enrichment in both the non-sea-salt potassium and chlorine is significantly larger than other inorganic species, suggesting that biomass-burning aerosols in Sanjiang Plain are mostly fresh and less aged. In addition, the WSOC-to-OC ratio is lower than that reported in biomass-burning aerosols in tropical regions, further supporting that biomass-burning aerosols in Sanjiang Plain are mostly primary and secondary organic aerosols may be not significant. A lower average δ 13 C value (-26.2‰) is observed during the biomass-burning period, indicating a dominant contribution from combustion of C3 plants in the studied region. Copyright © 2015. Published by Elsevier B.V.

  4. Impact of sulfuric and nitric acids on carbonate dissolution, and the associated deficit of CO2 uptake in the upper-middle reaches of the Wujiang River, China

    NASA Astrophysics Data System (ADS)

    Huang, Qi-bo; Qin, Xiao-qun; Liu, Peng-yu; Zhang, Lian-kai; Su, Chun-tian

    2017-08-01

    Carbonate weathering and the CO2 consumption in karstic area are extensive affected by anthropogenic activities, especially sulfuric and nitric acids usage in the upper-middle reaches of Wujiang River, China. The carbonic acid would be substituted by protons from sulfuric and nitric acids which can be reduce CO2 absorption. Therefore, The goal of this study was to highlight the impacts of sulfuric and nitric acids on carbonate dissolution and the associated deficit of CO2 uptaking during carbonate weathering. The hydrochemistries and carbon isotopic signatures of dissolved inorganic carbon from groundwater were measured during the rainy season (July; 41 samples) and post-rainy season (October; 26 samples). Our results show that Ca2 + and Mg2 + were the dominant cations (55.87-98.52%), and HCO3- was the dominant anion (63.63-92.87%). The combined concentrations of Ca2 + and Mg2 + commonly exceeded the equivalent concentration of HCO3-, with calculated [Ca2 + + Mg2 +]/[HCO3-] equivalent ratios of 1.09-2.12. The mean measured groundwater δ13CDIC value (- 11.38‰) was higher than that expected for carbonate dissolution mediated solely by carbonic acid (- 11.5‰), and the strong positive correlation of these values with [SO42 - + NO3-]/HCO3- showed that additional SO42 - and NO3- were required to compensate for this cation excess. Nitric and sulfuric acids are, therefore, suggested to have acted as the additional proton-promoted weathering agents of carbonate in the region, alongside carbonic acid. The mean contribution of atmospheric/pedospheric CO2 to the total aquatic HCO3- decreased by 15.67% (rainy season) and 14.17% (post-rainy season) due to the contributions made by these acids. The annual mean deficit of soil CO2 uptake by carbonate weathering across the study area was 14.92%, which suggests that previous workers may have overestimated the absorption of CO2 by carbonate weathering in other karstic areas worldwide.

  5. Impact of sulfuric and nitric acids on carbonate dissolution, and the associated deficit of CO2 uptake in the upper-middle reaches of the Wujiang River, China.

    PubMed

    Huang, Qi-Bo; Qin, Xiao-Qun; Liu, Peng-Yu; Zhang, Lian-Kai; Su, Chun-Tian

    2017-08-01

    Carbonate weathering and the CO 2 consumption in karstic area are extensive affected by anthropogenic activities, especially sulfuric and nitric acids usage in the upper-middle reaches of Wujiang River, China. The carbonic acid would be substituted by protons from sulfuric and nitric acids which can be reduce CO 2 absorption. Therefore, The goal of this study was to highlight the impacts of sulfuric and nitric acids on carbonate dissolution and the associated deficit of CO 2 uptaking during carbonate weathering. The hydrochemistries and carbon isotopic signatures of dissolved inorganic carbon from groundwater were measured during the rainy season (July; 41 samples) and post-rainy season (October; 26 samples). Our results show that Ca 2+ and Mg 2+ were the dominant cations (55.87-98.52%), and HCO 3 - was the dominant anion (63.63-92.87%). The combined concentrations of Ca 2+ and Mg 2+ commonly exceeded the equivalent concentration of HCO 3 - , with calculated [Ca 2+ +Mg 2+ ]/[HCO 3 - ] equivalent ratios of 1.09-2.12. The mean measured groundwater δ 13 C DIC value (-11.38‰) was higher than that expected for carbonate dissolution mediated solely by carbonic acid (-11.5‰), and the strong positive correlation of these values with [SO 4 2- +NO 3 - ]/HCO 3 - showed that additional SO 4 2- and NO 3 - were required to compensate for this cation excess. Nitric and sulfuric acids are, therefore, suggested to have acted as the additional proton-promoted weathering agents of carbonate in the region, alongside carbonic acid. The mean contribution of atmospheric/pedospheric CO 2 to the total aquatic HCO 3 - decreased by 15.67% (rainy season) and 14.17% (post-rainy season) due to the contributions made by these acids. The annual mean deficit of soil CO 2 uptake by carbonate weathering across the study area was 14.92%, which suggests that previous workers may have overestimated the absorption of CO 2 by carbonate weathering in other karstic areas worldwide. Copyright © 2017

  6. Comparison of carbon uptake estimates from forest inventory and Eddy-Covariance for a montane rainforest in central Sulawesi

    NASA Astrophysics Data System (ADS)

    Heimsch, Florian; Kreilein, Heiner; Rauf, Abdul; Knohl, Alexander

    2016-04-01

    Rainforests in general and montane rainforests in particular have rarely been studied over longer time periods. We aim to provide baseline information of a montane tropical forest's carbon uptake over time in order to quantify possible losses through land-use change. Thus we conducted a re-inventory of 22 10-year old forest inventory plots, giving us a rare opportunity to quantify carbon uptake over such a long time period by traditional methods. We discuss shortfalls of such techniques and why our estimate of 1.5 Mg/ha/a should be considered as the lower boundary and not the mean carbon uptake per year. At the same location as the inventory, CO2 fluxes were measured with the Eddy-Covariance technique. Measurements were conducted at 48m height with an LI 7500 open-path infrared gas analyser. We will compare carbon uptake estimates from these measurements to those of the more conventional inventory method and discuss, which factors are probably responsible for differences.

  7. Multifunctional organic–inorganic hybrid nanoparticles and nanosheets based on chitosan derivative and layered double hydroxide: cellular uptake mechanism and application for topical ocular drug delivery

    PubMed Central

    Chi, Huibo; Gu, Yan; Xu, Tingting; Cao, Feng

    2017-01-01

    To study the cellular uptake mechanism of multifunctional organic–inorganic hybrid nanoparticles and nanosheets, new chitosan–glutathione–valine–valine-layered double hydroxide (CG-VV-LDH) nanosheets with active targeting to peptide transporter-1 (PepT-1) were prepared, characterized and further compared with CG-VV-LDH nanoparticles. Both organic–inorganic hybrid nanoparticles and nanosheets showed a sustained release in vitro and prolonged precorneal retention time in vivo, but CG-VV-LDH nanoparticles showed superior permeability in the isolated cornea of rabbits than CG-VV-LDH nanosheets. Furthermore, results of cellular uptake on human corneal epithelial primary cells (HCEpiC) and retinal pigment epithelial (ARPE-19) cells indicated that both clathrin-mediated endocytosis and active transport of PepT-1 are involved in the internalization of CG-VV-LDH nanoparticles and CG-VV-LDH nanosheets. In summary, the CG-VV-LDH nanoparticle may be a promising carrier as a topical ocular drug delivery system for the treatment of ocular diseases of mid-posterior segments, while the CG-VV-LDH nanosheet may be suitable for the treatment of ocular surface diseases. PMID:28280329

  8. Spatial sensitivity of inorganic carbon to model setup: North Sea and Baltic Sea with ECOSMO

    NASA Astrophysics Data System (ADS)

    Castano Primo, Rocio; Schrum, Corinna; Daewel, Ute

    2015-04-01

    In ocean biogeochemical models it is critical to capture the key processes adequately so they do not only reproduce the observations but that those processes are reproduced correctly. One key issue is the choice of parameters, which in most cases are estimates with large uncertainties. This can be the product of actual lack of detailed knowledge of the process, or the manner the processes are implemented, more or less complex. In addition, the model sensitivity is not necessarily homogenous across the spatial domain modelled, which adds another layer of complexity to biogeochemical modelling. In the particular case of the inorganic carbon cycle, there are several sets of carbonate constants that can be chosen. The calculated air-sea CO2 flux is largely dependent on the parametrization chosen. In addition, the different parametrizations all the underlying processes that in some way impact the carbon cycle beyond the carbonate dissociation and fluxes give results that can be significantly different. Examples of these processes are phytoplankton growth rates or remineralization rates. Despite their geographical proximity, the North and Baltic Seas exhibit very different dynamics. The North Sea receives important inflows of Atlantic waters, while the Baltic Sea is an almost enclosed system, with very little exchange from the North Sea. Wind, tides, and freshwater supply act very differently, but dominantly structure the ecosystem dynamics on spatial and temporal scales. The biological community is also different. Cyanobacteria, which are important due to their ability to fix atmospheric nitrogen, and they are only present in the Baltic Sea. These differentiating features have a strong impact in the biogeochemical cycles and ultimately shape the variations in the carbonate chemistry. Here the ECOSMO model was employed on the North Sea and Baltic Sea. The model is set so both are modelled at the same time, instead of having them run separately. ECOSMO is a 3-D coupled

  9. Long term trend and interannual variability of land carbon uptake — the attribution and processes

    NASA Astrophysics Data System (ADS)

    Fu, Zheng

    2017-04-01

    Ecosystem carbon (C) uptake in terrestrial ecosystems has increased over the past five decades, but with large interannual variability (IAV). However, we are not clear on the attribution and the processes that control the long-term trend and IAV of land C uptake. Using atmospheric inversion net ecosystem exchange (NEE) data, we quantified the trend and IAV of NEE across the globe, the Northern Hemisphere (NH), and the Southern Hemisphere (SH), and decomposed NEE into carbon uptake amplitude and duration during each year from 1979-2013. We found the NH rather than the SH determined the IAV, while both hemispheres contributed equivalently to the global NEE trend. Different ecosystems in the NH and SH had differential relative contributions to their trend and IAV. The long-term trends of increased C uptake across the globe and the SH were attributed to both extended duration and increasing amplitude of C uptake. The shortened duration of uptake in the NH partly offsets the effects of increased NEE amplitude, making the net C uptake trend the same as that of the SH. The change in NEE IAV was also linked to changes in the amplitude and duration of uptake, but they worked in different ways in the NH, SH and globe. The fundamental attributions of amplitude and duration of C uptake revealed in this study are helpful to better understand the mechanisms underlying the trend and IAV of land C uptake. Our findings also suggest the critical roles of grassland and croplands in the NH in contributing to the trend and IAV of land C uptake.

  10. Inorganic Carbon and Oxygen Dynamics in a Marsh-dominated Estuary

    NASA Astrophysics Data System (ADS)

    Wang, S. R.; Di Iorio, D.; Cai, W. J.; Hopkinson, C.

    2017-12-01

    A free-water mass balance-based study was conducted to address the rate of metabolism and net carbon exchange for the tidal wetland and estuarine portion of the coastal ocean and the uncertainties associated with this approach were assessed. Open water diurnal O2 and dissolved inorganic carbon (DIC) were measured seasonally in a salt marsh-estuary in Georgia, U.S.A. with a focus on the marsh-estuary linkage associated with tidal flooding. We observed that the overall estuarine system was a net source of CO2 to the atmosphere and coastal ocean and a net sink for oceanic and atmospheric O2. Rates of metabolism were extremely high, with respiration (43 mol m-2 yr-1) greatly exceeding gross primary production (28 mol m-2 yr-1), such that the overall system was net heterotrophic. Metabolism measured with DIC were higher than with O2, which we attribute to high rates of anaerobic respiration and reduced sulfur storage in salt marsh sediments, and we assume substantial levels of anoxygenic photosynthesis. We found gas exchange from a flooded marsh is substantial, accounting for about 28% of total O2 and CO2 air-water exchange. A significant percentage of the overall estuarine aquatic metabolism is attributable to metabolism of marsh organisms during inundation. Our study suggests not rely on oceanographic stoichiometry to convert from O2to C based measurements when constructing C balances for the coastal ocean. We also suggest eddy covariance measurements of salt marsh net ecosystem exchange underestimate net ecosystem production as they do not account for lateral DIC exchange associated with marsh tidal inundation. With the increase of global temperature and sea level rise, salt marshes are likely to export more inorganic carbon to the atmosphere and the coastal ocean due to the decrease of solubility, the increase of aquatic and benthic metabolic activities and the longer marsh inundation.

  11. Contributions of secondary forest and nitrogen dynamics to terrestrial carbon uptake

    NASA Astrophysics Data System (ADS)

    Yang, X.; Richardson, T. K.; Jain, A. K.

    2010-10-01

    We use a terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM) to investigate the impacts of nitrogen dynamics on regrowing secondary forests over the 20th century. We further examine what the impacts of nitrogen deposition and land use change history are on terrestrial carbon uptake since preindustrial time. Our results suggest that global total net land use emissions for the 1990s associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher than if secondary forest regrowth is considered. Results also show that without considering the nitrogen dynamics and deposition, the estimated global total secondary forest sink for the 1990s is 0.90 GtC/yr or about 0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting nutrient in the intact primary forests in tropical regions, our study suggests that nitrogen becomes a limiting nutrient for regrowing secondary forests of the tropical regions, in particular Latin America and Tropical Africa. This is because land use change activities, especially wood harvest, removes large amounts of nitrogen from the system when slash is burnt or wood is removed for harvest. However, our model results show that carbon uptake is enhanced in the tropical secondary forests of the Indian region. We argue that this may be due to enhanced nitrogen mineralization and increased nitrogen availability following land use change in the Indian tropical forest ecosystems. Results also demonstrate that there is a significant amount of carbon accumulating in the Northern Hemisphere where most land use changes and forest regrowth has occurred in recent decades. This study indicates

  12. Contributions of secondary forest and nitrogen dynamics to terrestrial carbon uptake

    NASA Astrophysics Data System (ADS)

    Yang, X.; Richardson, T. K.; Jain, A. K.

    2010-04-01

    We use a terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM) to investigate the impacts of nitrogen dynamics on regrowing secondary forests over the 20th century. We further examine what the impacts of nitrogen deposition and land use change history are on terrestrial carbon uptake since preindustrial time. Our results suggest that global total net land use emissions for the 1990s associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher than if secondary forest regrowth is considered. Results also show that without considering the nitrogen dynamics and deposition, the estimated global total secondary forest sink for the 1990s is 0.90 GtC/yr or about 0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting nutrient in the intact primary forests in tropical regions, our study suggests that nitrogen becomes a limiting nutrient for regrowing secondary forests of the tropical regions, in particular Latin America and Tropical Africa. This is because land use change activities, especially wood harvest, removes large amounts of nitrogen from the system when slash is burnt or wood is removed for harvest. However, our model results show that carbon uptake is enhanced in the tropical secondary forests of the Indian region. We argue that this may be due to enhanced nitrogen mineralization and increased nitrogen availability following land use change in the Indian tropical forest ecosystems. Results also demonstrate that there is a significant amount of carbon accumulating in the Northern Hemisphere where most land use changes and forest regrowth has occurred in recent decades. This study indicates

  13. Nitrogen feedbacks increase future terrestrial ecosystem carbon uptake in an individual-based dynamic vegetation model

    NASA Astrophysics Data System (ADS)

    Wårlind, D.; Smith, B.; Hickler, T.; Arneth, A.

    2014-11-01

    Recently a considerable amount of effort has been put into quantifying how interactions of the carbon and nitrogen cycle affect future terrestrial carbon sinks. Dynamic vegetation models, representing the nitrogen cycle with varying degree of complexity, have shown diverging constraints of nitrogen dynamics on future carbon sequestration. In this study, we use LPJ-GUESS, a dynamic vegetation model employing a detailed individual- and patch-based representation of vegetation dynamics, to evaluate how population dynamics and resource competition between plant functional types, combined with nitrogen dynamics, have influenced the terrestrial carbon storage in the past and to investigate how terrestrial carbon and nitrogen dynamics might change in the future (1850 to 2100; one representative "business-as-usual" climate scenario). Single-factor model experiments of CO2 fertilisation and climate change show generally similar directions of the responses of C-N interactions, compared to the C-only version of the model as documented in previous studies using other global models. Under an RCP 8.5 scenario, nitrogen limitation suppresses potential CO2 fertilisation, reducing the cumulative net ecosystem carbon uptake between 1850 and 2100 by 61%, and soil warming-induced increase in nitrogen mineralisation reduces terrestrial carbon loss by 31%. When environmental changes are considered conjointly, carbon sequestration is limited by nitrogen dynamics up to the present. However, during the 21st century, nitrogen dynamics induce a net increase in carbon sequestration, resulting in an overall larger carbon uptake of 17% over the full period. This contrasts with previous results with other global models that have shown an 8 to 37% decrease in carbon uptake relative to modern baseline conditions. Implications for the plausibility of earlier projections of future terrestrial C dynamics based on C-only models are discussed.

  14. Coherence between woody carbon uptake and net ecosystem productivity at five eddy-covariance sites

    NASA Astrophysics Data System (ADS)

    Babst, F.; Bouriaud, O.; Papale, D.; Gielen, B.; Janssens, I.; Nikinmaa, E.; Ibrom, A.; Wu, J.; Bernhofer, C.; Koestner, B.; Gruenwald, T.; Seufert, G.; Ciais, P.; Frank, D. C.

    2013-12-01

    Forest growth ranks amongst the most important processes that determine the carbon balance of terrestrial ecosystems. Quantifications of forest carbon cycling can be made e.g. using biometric and eddy-covariance (EC) techniques. Both offer different perspectives on carbon uptake and attempts to combine them have been inconsistent and variably successful in the past. This contributes to persistent uncertainties regarding carbon allocation in forest ecosystems and complicates precise vegetation model parameterization. Aiming to reconcile assessments of carbon cycling from biometric and EC techniques, we measured radial tree growth and wood density at five long-term EC stations across Europe. The resulting records were used to calculate annual carbon uptake during above-ground wood formation and compared to monthly and seasonal CO2-flux measurements. Efforts were made to identify i) the time periods when EC and tree-ring data correspond best in different parts of Europe and ii) the fraction of eddy-fluxes which is associated with changes in above-ground woody carbon stocks. Biometric measurements and net ecosystem productivity (NEP) proved largely compatible at seasonal time scales while relationships with gross primary productivity (GPP) were often weaker. Results suggest a partitioning of sequestered carbon mainly used for volume increase (January-June) and a combination of cell-wall thickening and storage (July-September). The inter-annual variability in above-ground woody carbon uptake was significantly linked with absolute productivity ranging between 69-366 g C m-2 y-1 at boreal and temperate sites, thereby accounting for 10-25% of GPP, 15-32% of TER, and 25-80% of NEP. These findings from sites representing the major European climate zones and tree species contribute to improved quantification of above-ground carbon allocation in forests. Furthermore, they refine knowledge on processes driving ecosystem productivity important for e.g. vegetation models and

  15. Variations in phytodetritus derived carbon uptake of the intertidal foraminifera Ammonia tepida and Haynesina germanica

    NASA Astrophysics Data System (ADS)

    Wukovits, Julia; Bukenberger, Patrick; Enge, Annekatrin; Wanek, Wolfgang; Watzka, Margarete; Heinz, Petra

    2016-04-01

    Phytodetritus represents a major component of particulate organic carbon in intertidal mudflats. Estuaries and tidal currents yield an extensive amount of these particles that display a substantial nutrient source for littoral food webs. For benthic foraminifera, a group of marine protists, phytodetritus serves as the main food source. Foraminifera are considered to play a significant role in marine carbon turnover processes and show seasonally very high population densities in intertidal sediments. Therefore, it is important to gather explicit data about the specific carbon uptake behavior of intertidal foraminiferal species. In this study, laboratory feeding experiments were carried out to observe phytodetrital carbon uptake of foraminiferal specimen collected in the German Wadden Sea. Artificially produced phytodetritus was labelled with 13C to follow carbon ingestion into foraminiferal cytoplasm over time at different simulated conditions. The experiments were performed with monocultures under exclusion of other meiofauna. Chlorophyte detritus (Dunaliella tertiolecta) was fed to the two common species Ammonia tepida and Haynesina germanica. Ammonia tepida showed a significantly higher affinity to this food source than H. germanica. Testing the effect of temperature revealed a significant decrease of carbon ingestion with increasing temperature in H. germanica. Observations focusing on A. tepida showed a rising phytodetrital carbon content in the biomass of juvenile individuals in contrast to adult foraminifera. In general, carbon uptake reaches saturation levels a few hours after food supply. Furthermore, A. tepida benefits from constant availability of fresh food rather than from a high amount of phytodetritus derived from a single food pulse. Our investigations showed that the foraminiferal impact on intertidal processing of phytodetrital carbon sources is species specific, temperature related and depends on developmental stage and input dynamics

  16. Biodynamic modeling of PCB uptake by Macoma balthica and Corbicula fluminea from sediment amended with activated carbon

    USGS Publications Warehouse

    McLeod, Pamela B.; Luoma, S.N.; Luthy, R.G.

    2008-01-01

    Activated carbon amendment was assessed in the laboratory as a remediation strategy for freshwater sediment contaminated with polychlorinated biphenyls (PCBs) from the Grasse River (near Massena, NY). Three end points were evaluated: aqueous equilibrium PCB concentration, uptake into semipermeable membrane devices (SPMDs), and 28-day bioaccumulation in the clam Corbicula fluminea. PCB uptake by water, SPMDs, and clams followed similar trends, with reductions increasing as a function of carbon dose. Average percent reductions in clam tissue PCBs were 67, 86, and 95% for activated carbon doses of 0.7, 1.3, and 2.5% dry wt, respectively. A biodynamic model that incorporates sediment geochemistry and dietary and aqueous uptake routes was found to agree well with observed uptake by C. fluminea in our laboratory test systems. Results from this study were compared to 28-day bioaccumulation experiments involving PCB-contaminated sediment from Hunters Point Naval Shipyard (San Francisco Bay, CA) and the clam Macoma balthica. Due to differences in feeding strategy, M. balthica deposit-feeds whereas C. fluminea filter-feeds, the relative importance of the aqueous uptake route is predicted to be much higher for C. fluminea than for M. balthica. Whereas M. balthica takes up approximately 90% of its body burden through sediment ingestion, C. fluminea only accumulates approximately 45% via this route. In both cases, results strongly suggest that it is the mass transfer of PCBs from native sediment to added carbon particles, not merely reductions in aqueous PCB concentrations, that effectively reduces PCB bioavailability and uptake by sediment-dwelling organisms. ?? 2008 American Chemical Society.

  17. [Mechanisms for the increased fertilizer nitrogen use efficiency of rice in wheat-rice rotation system under combined application of inorganic and organic fertilizers].

    PubMed

    Liu, Yi-Ren; Li, Xiang; Yu, Jie; Shen, Qi-Rong; Xu, Yang-Chun

    2012-01-01

    A pot experiment was conducted to study the effects of combined application of organic and inorganic fertilizers on the nitrogen uptake by rice and the nitrogen supply by soil in a wheat-rice rotation system, and approach the mechanisms for the increased fertilizer nitrogen use efficiency of rice under the combined fertilization from the viewpoint of microbiology. Comparing with applying inorganic fertilizers, combined application of organic and inorganic fertilizers decreased the soil microbial biomass carbon and nitrogen and soil mineral nitrogen contents before tillering stage, but increased them significantly from heading to filling stage. Under the combined fertilization, the dynamics of soil nitrogen supply matched best the dynamics of rice nitrogen uptake and utilization, which promoted the nitrogen accumulation in rice plant and the increase of rice yield and biomass, and increased the fertilizer nitrogen use efficiency of rice significantly. Combined application of inorganic and organic fertilizers also promoted the propagation of soil microbes, and consequently, more mineral nitrogen in soil was immobilized by the microbes at rice early growth stage, and the immobilized nitrogen was gradually released at the mid and late growth stages of rice, being able to better satisfy the nitrogen demand of rice in its various growth and development stages.

  18. Preliminary Earth System Modeling (cGENIE) of Paired Organic and Inorganic Carbon Isotope Records to Investigate Carbon Cycle Behavior During the Triassic-Jurassic Transition

    NASA Astrophysics Data System (ADS)

    Yager, J. A.; Stellmann, J. L.; West, A. J.; Corsetti, F. A.; Berelson, W.; Bottjer, D. J.; Rosas, S.

    2016-12-01

    The stable C isotope composition of marine carbonate and organic C yields information regarding major changes in global carbon cycling over geologic time. Excursions from baseline C isotope compositions during the Late Triassic and early Jurassic coincide with the end-Triassic mass extinction. Much remains to be understood about the global extent of these excursions, and about their causes. Here, we use observations from a record from Northern Peru (Levanto) to generate hypotheses concerning C cycle changes, focusing on comparison to other sections spanning the Triassic-Jurassic boundary. Our observations include a decoupling between organic and inorganic C isotopes in some records, broad similarities in the pattern of excursions between sections, and a potential offset between the major ocean basins (Tethys and Panthalassa) in both inorganic and organic C isotope records. We are currently adapting a spatially resolved Earth System Model (cGENIE) for this time period with the goal of using this model to explore possible mechanistic causes of these observations, aiming to tie the C isotope records to changes in global carbon cycle dynamics at the time.

  19. Reduced carbon uptake during the 2010 Northern Hemisphere summer from GOSAT

    NASA Astrophysics Data System (ADS)

    Guerlet, S.; Basu, S.; Butz, A.; Krol, M.; Hahne, P.; Houweling, S.; Hasekamp, O. P.; Aben, I.

    2013-05-01

    Column-averaged dry air mole fractions of carbon dioxide (XCO2) measured by the Greenhouse Gases Observing Satellite (GOSAT) reveal significant interannual variation (IAV) of CO2uptake during the Northern Hemisphere summer between 2009 and 2010. The XCO2drawdown in 2010 is shallower than in 2009 by 2.4 ppm and 3.0 ppm over North America and Eurasia, respectively. Reduced carbon uptake in the summer of 2010 is most likely due to the heat wave in Eurasia driving biospheric fluxes and fire emissions. A joint inversion of GOSAT and surface data estimates an integrated biospheric and fire emission anomaly in April-September of 0.89 ±0.20 PgC over Eurasia. In contrast, inversions of surface measurements alone fail to replicate the observed XCO2IAV and underestimate emission IAV over Eurasia. This shows the value of GOSAT XCO2in constraining the response of land-atmosphere exchange of CO2 to climate events.

  20. Photosynthetic use of inorganic carbon in deep-water kelps from the Strait of Gibraltar.

    PubMed

    García-Sánchez, María Jesús; Delgado-Huertas, Antonio; Fernández, José Antonio; Flores-Moya, Antonio

    2016-03-01

    Mechanisms of inorganic carbon assimilation were investigated in the four deep-water kelps inhabiting sea bottoms at the Strait of Gibraltar; these species are distributed at different depths (Saccorhiza polysiches at shallower waters, followed by Laminaria ochroleuca, then Phyllariopsis brevipes and, at the deepest bottoms, Phyllariopsis purpurascens). To elucidate the capacity to use HCO3(-) as a source of inorganic carbon for photosynthesis in the kelps, different experimental approaches were used. Specifically, we measured the irradiance-saturated gross photosynthetic rate versus pH at a constant dissolved inorganic carbon (DIC) concentration of 2 mM, the irradiance-saturated apparent photosynthesis (APS) rate versus DIC, the total and the extracellular carbonic anhydrase (CAext), the observed and the theoretical photosynthetic rates supported by the spontaneous dehydration of HCO3(-) to CO2, and the δ(13)C signature in tissues of the algae. While S. polyschides and L. ochroleuca showed photosynthetic activity at pH 9.5 (around 1.0 µmol O2 m(-2) s(-1)), the activity was close to zero in both species of Phyllariopsis. The APS versus DIC was almost saturated for the DIC values of natural seawater (2 mM) in S. polyschides and L. ochroleuca, but the relationship was linear in P. brevipes and P. purpurascens. The four species showed total and CAext activities but the inhibition of the CAext originated the observed photosynthetic rates at pH 8.0 to be similar to the theoretical rates that could be supported by the spontaneous dehydration of HCO3(-). The isotopic (13)C signatures ranged from -17.40 ± 1.81 to -21.11 ± 1.73 ‰ in the four species. Additionally, the δ(13)C signature was also measured in the deep-water Laminaria rodriguezii growing at 60-80 m, showing even a more negative value of -26.49 ± 1.25 ‰. All these results suggest that the four kelps can use HCO3(-) as external carbon source for photosynthesis mainly by the action of external CAext, but

  1. Effects of Land Use and Lithology on the Origin and Cycling of Dissolved Inorganic Carbon in the Brazos River, Texas

    NASA Astrophysics Data System (ADS)

    Zeng, F.; Masiello, C. A.

    2009-12-01

    Global rivers annually receive significant amounts of both inorganic and organic carbon from land. The fate of this terrestrial carbon depends largely on factors such as climate, lithology, land use and topography. In this study, we focused on dissolved inorganic carbon (DIC). We directly measured the partial pressure of CO2 (pCO2), and stable and radiocarbon isotopes of riverine DIC to understand how land use and lithology control the origin and cycling of DIC in the Brazos River. We observed a significant difference in the sources and fate of DIC between the middle and lower Brazos. In the middle Brazos, a combination of damming and waste water discharge from urban areas appears to have promoted algal growth, resulting in low pCO2 (646 ± 216 μatm) and young DIC (Δ14C = +85 ± 63‰) in the river water. In the lower Brazos, higher pCO2 (1174 ± 418 μatm) and much older riverine DIC (Δ14C = -151 ± 52‰) are due to a combination of the presence of easily erodible carbonate bedrock (marl) and oyster shells used as construction aggregates, and old organic matter lost from soils caused by agricultural activities. Overall, of the terrestrial inorganic carbon the Brazos received, a larger amount is delivered to the ocean while a smaller fraction is returned to the atmosphere through CO2 outgassing, which is different from the observation in the Amazon River.

  2. Comparing carbon to carbon: Organic and inorganic carbon balances across nitrogen fertilization gradients in rainfed vs. irrigated Midwest US cropland

    NASA Astrophysics Data System (ADS)

    Hamilton, S. K.; McGill, B.

    2017-12-01

    The top meter of the earth's soil contains about twice the amount of carbon than the atmosphere. Agricultural management practices influence whether a cropland soil is a net carbon source or sink. These practices affect both organic and inorganic carbon cycling although the vast majority of studies examine the former. We will present results from several rarely-compared carbon fluxes: carbon dioxide emissions and sequestration from lime (calcium carbonate) weathering, dissolved gases emitted from groundwater-fed irrigation, dissolved organic carbon (DOC) leaching to groundwater, and soil organic matter storage. These were compared in a corn-soybean-wheat rotation under no-till management across a nitrogen fertilizer gradient where half of the replicated blocks are irrigated with groundwater. DOC and liming fluxes are also estimated from a complementary study in neighboring plots comparing a gradient of management practices from conventional to biologically-based annuals and perennials. These studies were conducted at the Kellogg Biological Station Long Term Ecological Research site in Michigan where previous work estimated that carbon dioxide emissions from liming accounted for about one quarter of the total global warming impact (GWI) from no-till systems—our work refines that figure. We will present a first time look at the GWI of gases dissolved in groundwater that are emitted when the water equilibrates with the atmosphere. We will explore whether nitrogen fertilizer and irrigation increase soil organic carbon sequestration by producing greater crop biomass and residues or if they enhance microbial activity, increasing decomposition of organic matter. These results are critical for more accurately estimating how intensive agricultural practices affect the carbon balance of cropping systems.

  3. Theoretical prediction of a novel inorganic fullerene-like family of silicon-carbon materials

    NASA Astrophysics Data System (ADS)

    Wang, Ruoxi; Zhang, Dongju; Liu, Chengbu

    2005-08-01

    In an effort to search for new inorganic fullerene-like structures, we designed a series of novel silicon-carbon cages, (SiC) n ( n = 6-36), based on the uniformly hybrid Si-C four- and six-membered-rings, and researched their geometrical and electronic structures, as well as their relative stabilities using the density function theory. Among these cages, the structures for n = 12, 16, and 36 were found to been energetically more favorable. The calculated disproportionation energy and binding energy per SiC unit show that the (SiC) 12 cage is the most stable one among these designed structures. The present calculations not only indicate that silicon-carbon fullerenes are promised to be synthesized in future, but also provide a new way for stabilizing silicon cages by uniformly doping carbon atoms into silicon structures.

  4. Uptake and Transformation of Methylated and Inorganic Antimony in Plants.

    PubMed

    Ji, Ying; Mestrot, Adrien; Schulin, Rainer; Tandy, Susan

    2018-01-01

    Used as a hardening agent in lead bullets, antimony (Sb) has become a major contaminant in shooting range soils of some countries including Switzerland. Soil contamination by Sb is also an environmental problem in countries with Sb-mining activities such as China and Bolivia. Because of its toxicity and relatively high mobility, there is concern over the risk of Sb transfer from contaminated soils into plants, and thus into the food chain. In particular there is very little information on the environmental behavior of methylated antimony, which can be produced by microbial biomethylation of inorganic Sb in contaminated soils. Using a new extraction and high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method, we investigated antimony speciation in roots and shoots of wheat, fescue, rye, and ryegrass plants exposed to trimethyl antimony(V) (TMSb), antimonite (Sb(III)), and antimonate (Sb(V)) in hydroponics. The total root Sb concentrations followed the order Sb(III) treatment > Sb(V) treatment > TMSb treatment, except for fescue. Shoot Sb concentrations, however, did not differ among the three treatments. In the Sb(V) treatment small quantities of TMSb were found in the roots, whereas no TMSb was detected in the roots of Sb(III)-treated plants. In contrast, similar concentrations of TMSb were found in the shoots in both inorganic Sb treatments. The results indicate that biomethylation of Sb may occur in plants. In the TMSb treatment TMSb was the major Sb species, but the two inorganic Sb species were also found both in shoots and roots along with some unknown Sb species, suggesting that also TMSb demethylation may occur within plant tissues. The results furthermore indicate that methylated Sb is more mobile in plants than inorganic Sb species. Knowledge about this is important in risk assessments of Sb-contaminated sites, as methylation may render Sb more toxic than inorganic Sb, as it is known for arsenic (As).

  5. Uptake and Transformation of Methylated and Inorganic Antimony in Plants

    PubMed Central

    Ji, Ying; Mestrot, Adrien; Schulin, Rainer; Tandy, Susan

    2018-01-01

    Used as a hardening agent in lead bullets, antimony (Sb) has become a major contaminant in shooting range soils of some countries including Switzerland. Soil contamination by Sb is also an environmental problem in countries with Sb-mining activities such as China and Bolivia. Because of its toxicity and relatively high mobility, there is concern over the risk of Sb transfer from contaminated soils into plants, and thus into the food chain. In particular there is very little information on the environmental behavior of methylated antimony, which can be produced by microbial biomethylation of inorganic Sb in contaminated soils. Using a new extraction and high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) method, we investigated antimony speciation in roots and shoots of wheat, fescue, rye, and ryegrass plants exposed to trimethyl antimony(V) (TMSb), antimonite (Sb(III)), and antimonate (Sb(V)) in hydroponics. The total root Sb concentrations followed the order Sb(III) treatment > Sb(V) treatment > TMSb treatment, except for fescue. Shoot Sb concentrations, however, did not differ among the three treatments. In the Sb(V) treatment small quantities of TMSb were found in the roots, whereas no TMSb was detected in the roots of Sb(III)-treated plants. In contrast, similar concentrations of TMSb were found in the shoots in both inorganic Sb treatments. The results indicate that biomethylation of Sb may occur in plants. In the TMSb treatment TMSb was the major Sb species, but the two inorganic Sb species were also found both in shoots and roots along with some unknown Sb species, suggesting that also TMSb demethylation may occur within plant tissues. The results furthermore indicate that methylated Sb is more mobile in plants than inorganic Sb species. Knowledge about this is important in risk assessments of Sb-contaminated sites, as methylation may render Sb more toxic than inorganic Sb, as it is known for arsenic (As). PMID

  6. Organic and Inorganic Carbon in the Rio Tinto (Spain) Deep Subsurface System: a Possible Model for Subsurface Carbon and Lithoautotrophs on Mars.

    NASA Astrophysics Data System (ADS)

    Bonaccorsi, R.; Stoker, C. R.; MARTE Science Team

    2007-12-01

    The subsurface is the key environment for searching for life on planets lacking surface life. Subsurface ecosystems are of great relevance to astrobiology including the search for past/present life on Mars. Conditions on the Martian surface do not support biological activity but the subsurface might preserve organics and host subsurface life [1]. A key requirement for the analysis of subsurface samples on Mars is the ability to characterize organic vs. inorganic carbon pools. This information is needed to determine if the sample contains organic material of biological origin and/ or to establish if pools of inorganic carbon can support subsurface biospheres. The Mars Analog Rio Tinto Experiment (MARTE) performed deep drilling of cores i.e., down to 165-m depth, in a volcanically-hosted-massive-sulfide deposit at Rio Tinto, Spain, which is considered an important analog of the Sinus Meridiani site on Mars. Results from MARTE suggest the existence of a relatively complex subsurface life including aerobic and anaerobic chemoautotrophs, and strict anaerobic methanogens sustained by Fe and S minerals in anoxic conditions, which is an ideal model analog for a deep subsurface Martian environment. We report here on the distribution of organic (C-org: 0.01-0.3Wt% and inorganic carbon (IC = 0.01-7.0 Wt%) in a subsurface rock system including weathered/oxidized i.e., gossan, and unaltered pyrite stockwork. Cores were analyzed from 3 boreholes (BH-4, BH-7, and BH-8) that penetrated down to a depth of ~165 m into massive sulfide. Nearsurface phyllosilicate rich-pockets contain the highest amounts of organics (0.3Wt%) [2], while the deeper rocks contain the highest amount of carbonates. Assessing the amount of C pools available throughout the RT subsurface brings key insight on the type of trophic system sustaining its microbial ecosystem (i.e., heterotrophs vs. autotrophs) and the biogeochemical relationships that characterize a new type of subsurface biosphere at RT. This

  7. Delayed and reduced carbon uptake in a subarctic peatland following an extreme winter event

    NASA Astrophysics Data System (ADS)

    Parmentier, F. J. W.; Rasse, D. P.; Lund, M.; Bjerke, J. W.; Drake, B. G.; Weldon, S.; Tømmervik, H. A.; Hansen, G.

    2017-12-01

    An increase in the frequency of extreme winter events in the Arctic may lead to more widespread damage to shrub-dominated ecosystems, including peatlands. In principle, such damage should reduce carbon uptake in the following summer, but the resilience of northern ecosystems to extreme winter events remains unclear due to a dearth of flux measurements from affected areas. In this talk, therefore, we report CO2 fluxes measured with eddy covariance from a peatland in northern Norway and show that vegetation productivity was delayed and reduced during the summer of 2014, following an extreme winter event. Strong frost and the absence of a protective snow cover in January of that year - its combined intensity unprecedented in the local climate record - led to severe dieback of the shrub species Calluna vulgaris and Empetrum nigrum. Similar vegetation damage was reported at the time along 1000 km of coastal Norway, indicating the widespread impact of this frost drought event. Consequently, gross primary production (GPP) showed a strong delayed response to temperature, from snowmelt up to the peak of summer, potentially reducing carbon uptake by 15 (0-24) g C m-2 ( 13% of GPP in that period). The delayed response of the vegetation was also exhibited in remotely-sensed NDVI values, with a maximum two weeks later than normal and at the lowest level in more than a decade. Photosynthesis was eventually stimulated by the warm and sunny summer, but ecosystem respiration increased as well - which limited net carbon uptake. This study shows that damage from a single extreme winter event can have a profound impact on ecosystem CO2 uptake, and it highlights the importance of including winter-induced shrub damage in terrestrial ecosystem models to accurately predict vegetation and carbon sequestration trends in the arctic and boreal region.

  8. Effect of inorganic nutrients on relative contributions of fungi and bacteria to carbon flow from submerged decomposing leaf litter

    Treesearch

    Vladislav Gulis; Keller Suberkropp

    2003-01-01

    The relative contributions of fungi and bacteria to carbon flow from submerged decaying plant litter at different levels of inorganic nutrients (N and P) were studied. We estimated leaf mass loss, fungal and bacterial biomass and production, and microbial respiration and constructed partial carbon budgets for red maple leaf disks precolonized in a stream and then...

  9. Uptake of organic nitrogen by plants

    Treesearch

    Torgny Nasholm; Knut Kielland; Ulrika Ganeteg

    2009-01-01

    Languishing for many years in the shadow of plant inorganic nitrogen (N) nutrition research, studies of organic N uptake have attracted increased attention during the last decade. The capacity of plants to acquire organic N, demonstrated in laboratory and field settings, has thereby been well established. Even so, the ecological significance of organic N uptake for...

  10. Cystine alters the renal and hepatic disposition of inorganic mercury and plasma thiol status

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zalups, Rudolfs K.; Lash, Lawrence H.

    2006-07-01

    In the present study, we determined whether cystine can inhibit, under certain conditions, the renal tubular uptake of inorganic mercury in vivo. We co-injected (i.v.) cystine with a non-toxic dose of mercuric chloride to rats and then studied the disposition of inorganic mercury during the next 24 h. We also determined if pretreatment with cystine influences the disposition of administered inorganic mercury. Moreover, plasma thiol status was examined after the intravenous administration of cystine with or without mercuric chloride. During the initial hour after co-injection, the renal tubular uptake of mercuric ions was diminished significantly relative to that in controlmore » rats. The inhibitory effects of cystine were evident in both the renal cortex and outer stripe of the outer medulla. In contrast, the renal accumulation of mercury increased significantly between the 1st and 12th hour after co-treatment. Urinary excretion and fecal excretion of mercury were greatly elevated in the rats co-treated with cystine and mercuric chloride. Thus, when cystine and mercury are administered simultaneously, cystine can serve as an inhibitor of the renal tubular uptake of mercury during the initial hour after co-treatment. In rats pretreated with cystine, the renal uptake of inorganic mercury was enhanced significantly relative to that in rats not pretreated with cystine. This enhanced accumulation of inorganic mercury correlated with the increased circulating concentrations of the reduced cysteine and glutathione. Additionally, the present findings indicate that thiol status is an important determinant of renal and hepatic disposition, and urinary and fecal excretion, of inorganic mercury.« less

  11. The southeastern continental shelf of the United States as an atmospheric CO 2 source and an exporter of inorganic carbon to the ocean

    NASA Astrophysics Data System (ADS)

    Aleck Wang, Zhaohui; Cai, Wei-Jun; Wang, Yongchen; Ji, Hongwei

    2005-10-01

    The US southeastern continental shelf, also known as the South Atlantic Bight (SAB), is a strong source of CO 2 to the atmosphere, which is in direct contrast to recent reports regarding other major continental shelves. Both spatial (cross-shelf) and seasonal variations of the CO 2 system were pronounced in the SAB. Sea surface pCO 2 in winter was undersaturated relative to the atmosphere, while oversaturation of pCO 2 dominated the entire shelf water in all other seasons. Annually, the SAB releases CO 2 to the atmosphere at an average rate of 30 g C m -2 (2.5 mol C m -2). This system also discharges dissolved inorganic carbon to the open ocean (30 g C m -2 yr -1). Methods of estimating CO 2 flux and DIC flux are critically evaluated and compared. A carbon mass balance model in the SAB is presented based on inorganic carbon fluxes from this study and organic carbon fluxes from literature. The carbon budget is much closer to balance by using this carbon flux approach than by direct measurements of primary production and respiration. It is concluded that the SAB is a net heterotrophic system annually. Intensified heating, elevated input of inorganic carbon from coastal salt marshes, microbial respiration of marsh-exported organic carbon and the lack of annual spring blooms all contribute to maintaining the SAB as a strong CO 2 source to the atmosphere during the warm seasons. In winter, the primary factor that governs the CO 2 sink in the SAB is likely the cooling process. Strong heterotrophy during warm seasons also sustains the SAB to be an exporter of inorganic carbon to the open ocean annually. The SAB shelf functions differently from the East China Sea, the North Atlantic European Shelves, and the Mid-Atlantic Bight as a source or sink of atmospheric CO 2. The SAB is classified as a "marsh-dominated" shelf as compared to other shelves in terms of carbon dynamics. Further work to study carbon dynamics in coastal margins is warranted to interpret their roles in

  12. Temperature Dependence of Inorganic Nitrogen Uptake: Reduced Affinity for Nitrate at Suboptimal Temperatures in Both Algae and Bacteria

    PubMed Central

    Reay, David S.; Nedwell, David B.; Priddle, Julian; Ellis-Evans, J. Cynan

    1999-01-01

    Nitrate utilization and ammonium utilization were studied by using three algal isolates, six bacterial isolates, and a range of temperatures in chemostat and batch cultures. We quantified affinities for both substrates by determining specific affinities (specific affinity = maximum growth rate/half-saturation constant) based on estimates of kinetic parameters obtained from chemostat experiments. At suboptimal temperatures, the residual concentrations of nitrate in batch cultures and the steady-state concentrations of nitrate in chemostat cultures both increased. The specific affinity for nitrate was strongly dependent on temperature (Q10 ≈ 3, where Q10 is the proportional change with a 10°C temperature increase) and consistently decreased at temperatures below the optimum temperature. In contrast, the steady-state concentrations of ammonium remained relatively constant over the same temperature range, and the specific affinity for ammonium exhibited no clear temperature dependence. This is the first time that a consistent effect of low temperature on affinity for nitrate has been identified for psychrophilic, mesophilic, and thermophilic bacteria and algae. The different responses of nitrate uptake and ammonium uptake to temperature imply that there is increasing dependence on ammonium as an inorganic nitrogen source at low temperatures. PMID:10347046

  13. Evaluation of carbon uptake and emissions by forests in Korea during the last thirty years (1973-2002).

    PubMed

    Choi, Sung-Deuk; Chang, Yoon-Seok

    2006-06-01

    The contribution of Korean forests to carbon sequestration for anthropogenic carbon emissions was evaluated. In addition, monitoring of carbon species released from forest fires was conducted. Despite a high carbon uptake by Korean forests, a tremendous increase in fossil fuel burning resulted in a small contribution by forests to carbon removal. The removal efficiency had a 5-31% range with an average of 12% during the period 1973-2002. In 2000, the amount of carbon released from burned trees corresponded to 1.6% of carbon uptake by forests. The distribution of surface CO concentration (ppb) derived from MOPITT (Measurement of Pollution in the Troposphere) showed high CO levels over the East/Japan Sea on April 10, 2000 when the largest forest fires occurred along the east coast of Korea. Trajectory analysis and ground CO measurements also indicated that CO levels over the East/Japan Sea were influenced by forest fires. This study suggests that continuous monitoring of carbon emissions from forest fires is needed for a more reliable estimate of carbon flux in the environment.

  14. Nitrogen recovery from wastewater using gas-permeable membranes: Impact of inorganic carbon content and natural organic matter

    USDA-ARS?s Scientific Manuscript database

    Gas-permeable membranes coupled with low-rate aeration are useful to recover ammonium from livestock effluents. In this study, the role of inorganic carbon (bicarbonate) to enhance the nitrogen (N) recovery process was evaluated using synthetic effluents with various ammonium to bicarbonate molar ra...

  15. High-Temperature Inorganic Self-Healing Inorganic Cement Composites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pyatina, Tatiana; Sugama, Toshifumi

    The data files below summarize the results from various experiments testing properties of high-temperature self-healing inorganic cement composites. These properties include cement-carbon steel bond strength, Young's modulus recovery, matrix recovery strength, and compressive strength and Yonug's modulus for cement composites modified with Pozzolanic Clay additives.

  16. Warmer temperatures reduce net carbon uptake, but not water use, in a mature southern Appalachian forest

    EPA Science Inventory

    Increasing air temperature is expected to extend growing season length in temperate, broadleaf forests, leading to potential increases in evapotranspiration and net carbon uptake. However, other key processes affecting water and carbon cycles are also highly temperature-dependent...

  17. Recent Advances in Inorganic Heterogeneous Electrocatalysts for Reduction of Carbon Dioxide.

    PubMed

    Zhu, Dong Dong; Liu, Jin Long; Qiao, Shi Zhang

    2016-05-01

    In view of the climate changes caused by the continuously rising levels of atmospheric CO2 , advanced technologies associated with CO2 conversion are highly desirable. In recent decades, electrochemical reduction of CO2 has been extensively studied since it can reduce CO2 to value-added chemicals and fuels. Considering the sluggish reaction kinetics of the CO2 molecule, efficient and robust electrocatalysts are required to promote this conversion reaction. Here, recent progress and opportunities in inorganic heterogeneous electrocatalysts for CO2 reduction are discussed, from the viewpoint of both experimental and computational aspects. Based on elemental composition, the inorganic catalysts presented here are classified into four groups: metals, transition-metal oxides, transition-metal chalcogenides, and carbon-based materials. However, despite encouraging accomplishments made in this area, substantial advances in CO2 electrolysis are still needed to meet the criteria for practical applications. Therefore, in the last part, several promising strategies, including surface engineering, chemical modification, nanostructured catalysts, and composite materials, are proposed to facilitate the future development of CO2 electroreduction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Ozone uptake, water loss and carbon exchange dynamics in annually drought-stressed Pinus ponderosa forests: measured trends and parameters for uptake modeling.

    PubMed

    Panek, Jeanne A

    2004-03-01

    This paper describes 3 years of physiological measurements on ponderosa pine (Pinus ponderosa Dougl. ex Laws.) growing along an ozone concentration gradient in the Sierra Nevada, California, including variables necessary to parameterize, validate and modify photosynthesis and stomatal conductance algorithms used to estimate ozone uptake. At all sites, gas exchange was under tight stomatal control during the growing season. Stomatal conductance was strongly correlated with leaf water potential (R2=0.82), which decreased over the growing season with decreasing soil water content (R2=0.60). Ozone uptake, carbon uptake, and transpirational water loss closely followed the dynamics of stomatal conductance. Peak ozone and CO2 uptake occurred in early summer and declined progressively thereafter. As a result, periods of maximum ozone uptake did not correspond to periods of peak ozone concentration, underscoring the inappropriateness of using current metrics based on concentration (e.g., SUM0, W126 and AOT40) for assessing ozone exposure risk to plants in this climate region. Both Jmax (maximum CO2-saturated photosynthetic rate, limited by electron transport) and Vcmax (maximum rate of Rubisco-limited carboxylation) increased toward the middle of the growing season, then decreased in September. Intrinsic water-use efficiency rose with increasing drought stress, as expected. The ratio of Jmax to Vcmax was similar to literature values of 2.0. Nighttime respiration followed a Q10 of 2.0, but was significantly higher at the high-ozone site. Respiration rates decreased by the end of the summer as a result of decreased metabolic activity and carbon stores.

  19. Regeneration of spent powdered activated carbon saturated with inorganic ions by cavitation united with ion exchange method.

    PubMed

    Li, Gang; Gao, Hong; Li, Yansheng; Yang, Huixin

    2011-06-01

    Using ion exchange resin as transfer media, regenerate powdered activated carbon (PAC) adsorbed inorganic ions by cavitation to enhance the transfer; we studied how the regeneration time and the mass ratio of resin and PAC influence the regeneration rate respectively through re-adsorption. The result showed that the effective regeneration of PAC saturated with inorganic ions was above 90% using ion exchange resin as media and transfer carrier, the quantity of PAC did not reduced but activated in the process. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  20. Nitrogen-doped ordered mesoporous carbon with a high surface area, synthesized through organic-inorganic coassembly, and its application in supercapacitors.

    PubMed

    Song, Yanfang; Li, Li; Wang, Yonggang; Wang, Congxiao; Guo, Zaipin; Xia, Yongyao

    2014-07-21

    A new nitrogen-doped ordered mesoporous carbon (N-doped OMC) is synthesized by using an organic-inorganic coassembly method, in which resol is used as the carbon precursor, dicyandiamide as the nitrogen precursor, silicate oligomers as the inorganic precursors, and F127 as the soft template. The N-doped OMC possesses a surface area as high as 1374 m(2)  g(-1) and a large pore size of 7.4 nm. As an electrode material for supercapacitors, the obtained carbon exhibits excellent cycling stability and delivers a reversible specific capacitance as high as 308 F g(-1) in 1 mol L(-1) H(2)SO(4) aqueous electrolyte, of which 58 % of the capacity is due to pseudo-capacitance. The large specific capacitance is attributed to proper pore size distributions, large surface area, and high nitrogen content. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Global and regional ocean carbon uptake and climate change: sensitivity to a substantial mitigation scenario

    NASA Astrophysics Data System (ADS)

    Vichi, Marcello; Manzini, Elisa; Fogli, Pier Giuseppe; Alessandri, Andrea; Patara, Lavinia; Scoccimarro, Enrico; Masina, Simona; Navarra, Antonio

    2011-11-01

    Under future scenarios of business-as-usual emissions, the ocean storage of anthropogenic carbon is anticipated to decrease because of ocean chemistry constraints and positive feedbacks in the carbon-climate dynamics, whereas it is still unknown how the oceanic carbon cycle will respond to more substantial mitigation scenarios. To evaluate the natural system response to prescribed atmospheric "target" concentrations and assess the response of the ocean carbon pool to these values, 2 centennial projection simulations have been performed with an Earth System Model that includes a fully coupled carbon cycle, forced in one case with a mitigation scenario and the other with the SRES A1B scenario. End of century ocean uptake with the mitigation scenario is projected to return to the same magnitude of carbon fluxes as simulated in 1960 in the Pacific Ocean and to lower values in the Atlantic. With A1B, the major ocean basins are instead projected to decrease the capacity for carbon uptake globally as found with simpler carbon cycle models, while at the regional level the response is contrasting. The model indicates that the equatorial Pacific may increase the carbon uptake rates in both scenarios, owing to enhancement of the biological carbon pump evidenced by an increase in Net Community Production (NCP) following changes in the subsurface equatorial circulation and enhanced iron availability from extratropical regions. NCP is a proxy of the bulk organic carbon made available to the higher trophic levels and potentially exportable from the surface layers. The model results indicate that, besides the localized increase in the equatorial Pacific, the NCP of lower trophic levels in the northern Pacific and Atlantic oceans is projected to be halved with respect to the current climate under a substantial mitigation scenario at the end of the twenty-first century. It is thus suggested that changes due to cumulative carbon emissions up to present and the projected concentration

  2. Constraints on Early Triassic carbon cycle dynamics from paired organic and inorganic carbon isotope records

    NASA Astrophysics Data System (ADS)

    Meyer, K. M.; Yu, M.; Lehrmann, D.; van de Schootbrugge, B.; Payne, J. L.

    2013-01-01

    Large δ13C excursions, anomalous carbonate precipitates, low diversity assemblages of small fossils, and evidence for marine euxinia in uppermost Permian and Lower Triassic strata bear more similarity to Neoproterozoic carbonates than to the remainders of the Permian and Triassic systems. Middle Triassic diversification of marine ecosystems coincided with the waning of anoxia and stabilization of the global carbon cycle, suggesting that environment-ecosystem linkages were important to biological recovery. However, the Earth system behavior responsible for these large δ13C excursions remains poorly constrained. Here we present a continuous Early Triassic δ13Corg record from south China and use it to test the extent to which Early Triassic excursions in δ13Ccarb record changes in the δ13C of marine dissolved inorganic carbon (DIC). Regression analysis demonstrates a significant positive correlation between δ13Corg and δ13Ccarb across multiple sections that span a paleoenvironmental gradient. Such a correlation is incompatible with diagenetic alteration because no likely mechanism will alter both δ13Corg and δ13Ccarb records in parallel and therefore strongly indicates a primary depositional origin. A simple explanation for this correlation is that a substantial portion of the preserved Corg was derived from the contemporaneous DIC pool, implying that the observed excursions reflect variation in the δ13C of the exogenic carbon reservoir (ocean, atmosphere, biomass). These findings support existing evidence that large δ13C excursions are primary and therefore strengthen the case that large-scale changes to the carbon cycle were mechanistically linked to the low diversity and small size of Early Triassic fossils. Associated sedimentary and biogeochemical phenomena further suggest that similar associations in Neoproterozoic and Cambrian strata may reflect the same underlying controls.

  3. Dissolved inorganic and organic carbon yields and fluxes in a permafrost catchment on the Qinghai-Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Wang, G.; Mao, T.; Zhang, T.; Chen, X.

    2015-12-01

    Riverine transport of carbon from terrestrial to the aquatic ecosystems is an important component of the global carbon cycle. A warming climate can inevitably accelerate the microbial breakdown of organic carbon and the release of carbon dioxide especially in frozen soils (permafrost) within Arctic and sub-Arctic regions. In addition, high hydraulic conductivity and low sorption capacity of the shallow soil active layer overlying impermeable permafrost together lead to quick DOM transport to streams. In different regions, the response of dissolved carbon to climate warming is different due to the differences in hydrology, climatic conditions, soil types, vegetation conditions, permafrost distribution, catchment size, flow paths. The Qinghai-Tibet Plateau (QTP), of which a significant portion is underlain by permafrost, is considered to be more sensitive to climatic warming than other regions. However, the knowledge of dissolved inorganic and organic carbon transport in the QTP is very limited. We compared the yields and fluxes of DIC/DOC in a small tropical permafrost catchment. Our results showed that: (1) the concentrations ranged from 7.8 to 30.9 mg L-1 for the DIC and ranged from 2.3 to 6.4 mg L-1 for the DOC, the ratio of DIC/DOC concentrations ranged from 2.2 to 5.7 with a mean value of 4.3; (2) the annual export approximately 3.56 t km-2 year-1 for the DIC and 0.73 t km-2 year-1 for the DOC, indicating that the dissolved carbon transported in majority under the inorganic form; (3) the seasonal variations in DIC/DOC export are strongly regulated by variability in runoff, meanwhile the concentration of DIC/DOC showed significant positive correlation with the thawing depth of the active layer and vegetation coverage. Our results provided an understanding about the characteristics of riverine dissolved carbons transport at a permafrost catchment scale on the QTP.

  4. Feasibility of CO₂/SO₂ uptake enhancement of calcined limestone modified with rice husk ash during pressurized carbonation.

    PubMed

    Chen, Huichao; Zhao, Changsui; Ren, Qiangqiang

    2012-01-01

    The calcination/carbonation cycle using calcium-based sorbents appears to be a viable method for carbon dioxide (CO₂) capture from combustion gases. Recent attempts to improve the CO₂/SO₂ uptake of a calcium-based sorbent modified by using rice husk ash (RHA) in the hydration process have succeeded in enhancing its effectiveness. The optimal mole ratio of RHA to calcined limestone (M(Si/Ca)) was adjusted to 0.2. The cyclic CO₂ capture characteristics and the SO₂ uptake activity of the modified sorbent were evaluated in a calcination/pressurized carbonation reactor system. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) spectrum of the sorbent were also taken to supplement the study. The results showed that the carbonation conversion was greatly increased for the sorbent with M(Si/Ca) ratio of 0.2. For this sorbent formulation the optimal operating conditions were 700-750 °C and 0.5-0.7 MPa. CO₂ absorption was not proportional to CO₂ concentration in the carbonation atmosphere, but was directly related to reaction time. The CO₂ uptake decreased in the presence of SO₂. SO₂ uptake increased, and the total calcium utilization was maintained over multiple cycles. Analysis has shown that the silicate component is evenly or well distributed, and this serves as a framework to prevent sintering, thus preserving the available microstructure for reaction. The sorbent also displayed high activity to SO₂ absorption and could be used to capture CO₂ and SO₂ simultaneously. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. An inorganic carbon transport system responsible for acclimation specific to air levels of CO2 in Chlamydomonas reinhardtii.

    PubMed

    Wang, Yingjun; Spalding, Martin H

    2006-06-27

    Many photosynthetic microorganisms acclimate to CO(2) limited environments by induction and operation of CO(2)-concentrating mechanisms (CCMs). Despite their central role in CCM function, inorganic carbon (Ci) transport systems never have been identified in eukaryotic photosynthetic organisms. In the green alga Chlamydomonas reinhardtii, a mutant, pmp1, was described in 1983 with deficiencies in Ci transport, and a Pmp1 protein-associated Ci uptake system has been proposed to be responsible for Ci uptake in low CO(2) (air level)-acclimated cells. However, even though pmp1 represents the only clear genetic link to Ci transport in microalgae and is one of only a very few mutants directly affecting the CCM itself, the identity of Pmp1 has remained unknown. Physiological analyses indicate that C. reinhardtii possesses multiple Ci transport systems responsible for acclimation to different levels of limiting CO(2) and that the Pmp1-associated transport system is required specifically for low (air level) CO(2) acclimation. In the current study, we identified and characterized a pmp1 allelic mutant, air dier 1 (ad1) that, like pmp1, cannot grow in low CO(2) (350 ppm) but can grow either in high CO(2) (5% CO(2)) or in very low CO(2) (<200 ppm). Molecular analyses revealed that the Ad1/Pmp1 protein is encoded by LciB, a gene previously identified as a CO(2)-responsive gene. LciB and three related genes in C. reinhardtii compose a unique gene family that encode four closely related, apparently soluble plastid proteins with no clearly identifiable conserved motifs.

  6. Organic-Inorganic Composites Toward Biomaterial Application.

    PubMed

    Miyazaki, Toshiki; Sugawara-Narutaki, Ayae; Ohtsuki, Chikara

    2015-01-01

    Bioactive ceramics are known to exhibit specific biological affinities and are able to show direct integration with surrounding bone when implanted in bony defects. However, their inadequate mechanical properties, such as low fracture toughness and high Young's modulus in comparison to natural bone, limit their clinical application. Bone is a kind of organic-inorganic composite where apatite nanocrystals are precipitated onto collagen fibre networks. Thus, one way to address these problems is to mimic the natural composition of bone by using bioactive ceramics via material designs based on organic-inorganic composites. In this chapter, the current research on the development of the various organic-inorganic composites designed for biomaterial applications has been reviewed. Various compounds such as calcium phosphate, calcium sulphate and calcium carbonate can be used for the inorganic phases to design composites with the desired mechanical and biological properties of bone. Not only classical mechanical mixing but also coating of the inorganic phase in aqueous conditions is available for the fabrication of such composites. Organic modifications using various polymers enable the control of the crystalline structure of the calcium carbonate in the composites. These approaches on the fabrication of organic-inorganic composites provide important options for biomedical materials with novel functions. © 2015 S. Karger AG, Basel.

  7. New multifunctional porous materials based on inorganic-organic hybrid single-walled carbon nanotubes: gas storage and high-sensitive detection of pesticides.

    PubMed

    Wang, Feng; Zhao, Jinbo; Gong, Jingming; Wen, Lili; Zhou, Li; Li, Dongfeng

    2012-09-10

    Single-walled carbon nanotubes (SWNTs) that are covalently functionalized with benzoic acid (SWNT-PhCOOH) can be integrated with transition-metal ions to form 3D porous inorganic-organic hybrid frameworks (SWNT-Zn). In particular, N(2)-adsorption analysis shows that the BET surface area increases notably from 645.3 to 1209.9 m(2)  g(-1) for SWNTs and SWNT-Zn, respectively. This remarkable enhancement in the surface area of SWNT-Zn is presumably due to the microporous motifs from benzoates coordinated to intercalated zinc ions between the functionalized SWNTs; this assignment was also corroborated by NLDFT pore-size distributions. In addition, the excess-H(2)-uptake maximum of SWNT-Zn reaches about 3.1 wt. % (12 bar, 77 K), which is almost three times that of the original SWNTs (1.2 wt. % at 12 bar, 77 K). Owing to its inherent conductivity and pore structure, as well as good dispersibility, SWNT-Zn is an effective candidate as a sensitive electrochemical stripping voltammetric sensor for organophosphate pesticides (OPs): By using solid-phase extraction (SPE) with SWNT-Zn-modified glassy carbon electrode, the detection limit of methyl parathion (MP) is 2.3 ng mL(-1). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Drivers of the Seasonal Carbon Cycle in the Coastal Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Pilcher, D.; Siedlecki, S. A.; Hermann, A. J.; Coyle, K. O.; Mathis, J. T.

    2016-02-01

    The Coastal Gulf of Alaska serves as a significant carbon sink annually, but varies seasonally from net carbon efflux in winter, to net carbon uptake from spring through fall. This significant uptake of anthropogenic CO2 combined with the naturally cold, low calcium carbonate surface waters is expected to accelerate ocean acidification. Observational evidence has already detected subsurface aragonite undersaturation, likely resulting from carbon remineralization of sinking organic matter. Other processes such as storm-induced vertical mixing, glacial runoff, temperature change, and nutrient supply can further modify the carbon cycle. Improving knowledge of these seasonal processes is critical for the region's fisheries that provide substantial ecosystem services and can be adversely impacted by sub-optimal aragonite saturation conditions. We use a regional model of the Coastal Gulf of Alaska coupled to an ecosystem model with full carbonate chemistry to investigate the physical and biogeochemical mechanisms that drive the seasonal carbon cycle. Boundary conditions are set from the coarser Northeast Pacific model, with alkalinity and carbon concentrations determined from empirical relationships with salinity. Model output from a 2009 hindcast simulation is compared to observations of alkalinity and dissolved inorganic carbon concentrations for model verification and to elucidate seasonal mechanisms.

  9. Carbon-Electrode-Tailored All-Inorganic Perovskite Solar Cells To Harvest Solar and Water-Vapor Energy.

    PubMed

    Duan, Jialong; Hu, Tianyu; Zhao, Yuanyuan; He, Benlin; Tang, Qunwei

    2018-05-14

    Moisture is the worst enemy for state-of-the-art perovskite solar cells (PSCs). However, the flowing water vapor within nanoporous carbonaceous materials can create potentials. Therefore, it is a challenge to integrate water vapor and solar energies into a single PSC device. We demonstrate herein all-inorganic cesium lead bromide (CsPbBr 3 ) solar cells tailored with carbon electrodes to simultaneously harvest solar and water-vapor energy. Upon interfacial modification and plasma treatment, the bifunctional PSCs yield a maximum power conversion efficiency up to 9.43 % under one sun irradiation according to photoelectric conversion principle and a power output of 0.158 μW with voltage of 0.35 V and current of 0.45 μA in 80 % relative humidity through the flowing potentials at the carbon/water interface. The initial efficiency is only reduced by 2 % on exposing the inorganic PSC with 80 % humidity over 40 days. The successful realization of physical proof-of-concept multi-energy integrated solar cells provides new opportunities of maximizing overall power output. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Understanding the carbon cycle in a Late Quaternary-age limestone aquifer system using radiocarbon of dissolved inorganic and organic carbon

    NASA Astrophysics Data System (ADS)

    Bryan, Eliza; Meredith, Karina T.; Baker, Andy; Andersen, Martin S.; Post, Vincent E. A.

    2017-04-01

    Estimating groundwater residence time is critical for our understanding of hydrogeological systems, for groundwater resource assessments and for the sustainable management of groundwater resources. Due to its capacity to date groundwater up to 30 thousand years old, as well as the ubiquitous nature of dissolved carbon (as organic and inorganic forms) in groundwater, 14C is the most widely used radiogenic dating technique in regional aquifers. However, the geochemistry of carbon in groundwater systems includes interaction with the atmosphere, biosphere and geosphere, which results in multiple sources and sinks of carbon that vary in time and space. Identifying these sources of carbon and processes relating to its release or removal is important for understanding the evolution of the groundwater and essential for residence time calculations. This study investigates both the inorganic and organic facets of the carbon cycle in groundwaters throughout a freshwater lens and mixing zone of a carbonate island aquifer and identifies the sources of carbon that contribute to the groundwater system. Groundwater samples were collected from shallow (5-20 m) groundwater wells on a small carbonate Island in Western Australia in September 2014 and analysed for major and minor ions, stable water isotopes (SWIs: δ18O, δ2H), 3H, 14C and 13C carbon isotope values of both DIC and DOC, and 3H. The composition of groundwater DOC was investigated by Liquid Chromatography-Organic Carbon Detection (LC-OCD) analysis. The presence of 3H (0.12 to 1.35 TU) in most samples indicates that groundwaters on the Island are modern, however the measured 14CDIC values (8.4 to 97.2 pmc) suggest that most samples are significantly older due to carbonate dissolution and recrystallisation reactions that are identified and quantified in this work. 14CDOC values (46.6 to 105.6 pMC) were higher than 14CDIC values and were well correlated with 3H values, however deeper groundwaters had lower 14CDOC values than

  11. Preliminary Study: Application of Off-Axis ICOS to Determine Stable Carbon Isotope in Dissolved Inorganic Carbon

    NASA Astrophysics Data System (ADS)

    Kim, Y. T.; Lee, J. M.; Hwang, J. H.; Piao, J.; Woo, N. C.

    2015-12-01

    CO2 is one of the major causes for global climate change. Because stable carbon isotope ratio is used to trace carbon source, several analytical techniques likes IRMS (Isotope Ratio Mass Spectrometry) and LAS (Laser Absorption Spectrometry) were extensively used. Off-axis ICOS, a kind of LAS, has merits on long-term stability and field application, therefore it is widely being used in CCS (Carbon Capture and Storage) field. The aim of this study is to extend the application scope of OA-ICOS to determine dissolved inorganic carbon (DIC). Because OA-ICOS showed dependence of δ13C on CO2 concentration, data processing is required. We tested CO2 Carbon Isotope Analyzer (CCIA-36-EP, Los Gatos Research) with both reference gas (δ13C= -28.28‰) and aqueous solutions prepared by dissolving sodium bicarbonate standards (δ13C= -12.26‰ and +3.96‰). The differences of δ13C between reference and measurement values are plotted by CO2 concentrations, then compared. At first, we checked the similarity between our curve pattern for reference gas and Guillon's research (δ13C= -43.99‰) by other Analyzer. To analyze aqueous samples, more errors can be caused than gas analysis. The carbon isotope fractionation occurs during dissolving standard reagents and extracting DIC as CO2 gas form. This effect is mixed with CO2 concentration dependence effect, therefore the curve patterns are different with that for reference gas. Our experiments are done for various δ13C values. It could be an important point to use OA-ICOS to analyze DIC, too.

  12. Interannual variability of terrestrial NEP and its attributions to carbon uptake amplitude and period

    NASA Astrophysics Data System (ADS)

    Niu, S.

    2015-12-01

    Earth system exhibits strong interannual variability (IAV) in the global carbon cycle as reflected in the year-to-year anomalies of the atmospheric CO2 concentration. Although various analyses suggested that land ecosystems contribute mostly to the IAV of atmospheric CO2 concentration, processes leading to the IAV in the terrestrial carbon (C) cycle are far from clear and hinder our effort in predicting the IAV of global C cycle. Previous studies on IAV of global C cycle have focused on the regulation of climatic variables in tropical or semiarid areas, but generated inconsistent conclusions. Using long-term eddy-flux measurements of net ecosystem production (NEP), atmospheric CO2 inversion NEP, and the MODIS-derived gross primary production (GPP), we demonstrate that seasonal carbon uptake amplitude (CUA) and period (CUP) are two key processes that control the IAV in the terrestrial C cycle. The two processes together explain 78% of the variations in the IAV in eddy covariance NEP, 70% in global atmospheric inversed NEP, and 53% in the IAV of GPP. Moreover, the three lines of evidence consistently show that variability in CUA is much more important than that of CUP in determining the variation of NEP at most eddy-flux sites, and most grids of global NEP and GPP. Our results suggest that the maximum carbon uptake potential in the peak-growing season is a determinant process of global C cycle internnual variability and carbon uptake period may play less important role than previous expectations. This study uncovers the most parsimonious, proximate processes underlying the IAV in global C cycle of the Earth system. Future research is needed to identify how climate factors affect the IAV in terrestrial C cycle through their influence on CUA and CUP.

  13. Basalt Weathering, Nutrient Uptake, And Carbon Release By An Exotic And A Native Arizona Grass Species Under Different Temperature Conditions

    NASA Astrophysics Data System (ADS)

    Gallas, G.; Dontsova, K.; Chorover, J.; Hunt, E.; Ravi, S.

    2010-12-01

    basalt weathering. All of the leachate samples showed higher pH than the input water, and the pH was elevated in treatments that contained grass. This indicated that in the presence of vegetation there was more proton absorption. The trends in total nitrogen concentrations indicate a dependence on temperature; the same can be said of anion concentrations. Anion leaching is lower at higher temperatures possibly due to greater plant uptake. Both organic and inorganic carbon concentrations were found to be higher in grass treatments than in control treatments. Because both dissolved CO2 and soluble organic exudates encourage mineral dissolution, this could be causative of the weathering enhancements observed. Denudation of nutrient elements differed between plant species and between temperatures, possibly relating to plant uptake and secondary mineral formation. This study gives unique insight into plant-mineral interactions as a function of plant species and temperature that is essential for understanding Earth systems under changing climate.

  14. Spatial variation of salt-marsh organic and inorganic deposition and organic carbon accumulation: Inferences from the Venice lagoon, Italy

    NASA Astrophysics Data System (ADS)

    Roner, M.; D'Alpaos, A.; Ghinassi, M.; Marani, M.; Silvestri, S.; Franceschinis, E.; Realdon, N.

    2016-07-01

    inorganic soil content near the edge is due to the preferential deposition of inorganic sediment from the adjacent creek, and to the rapid decomposition of the relatively large biomass production. The higher organic matter content in the inner part of the marsh results from the small amounts of suspended sediment that makes it to the inner marsh, and to the low decomposition rate which more than compensates for the lower biomass productivity in the low-lying inner zones. Finally, the average soil organic carbon density from the LOI measurements is estimated to be 0.044 g C cm-3. The corresponding average carbon accumulation rate for the San Felice and Rigà salt marshes, 132 g C m-2 yr-1, highlights the considerable carbon stock and sequestration rate associated with coastal salt marshes.

  15. Role of ocean isopycnal mixing in setting the uptake of anthropogenic carbon

    NASA Astrophysics Data System (ADS)

    Gnanadesikan, A.; Pradal, M. A. S.; Abernathey, R. P.

    2014-12-01

    The magnitude of the isopycnal stirring coefficient ARedi is poorly constrained from data and varies greatly across Earth System Models. This paper documents the impact of such uncertainty on the oceanic carbon cycle. We compare six spatial representations of ARedi. Four constant values (400, 800, 1200 and 2400 m2/s) are used to explore the difference between using the low values found in many models and the higher values seen in observational estimates. Models are also run with two spatially dependent values of ARedi based on altimetry, one which captures the fully two-dimensional structure of the mixing coefficient, the other of which looks at the zonally averaged structure alone. Under global warming significant changes are seen in the biological pump in convective regions, but these changes are largely locally compensated by changes in preformed DIC. Instead, differences in anthropogenic uptake of carbon are largely centered in the tropics, and can be well described in terms of a relatively simple diffusive approximation. Using ideal age as a tracer can give insight into the expected behavior of the models. The rate of oceanic mixing represents a quantitatively significant uncertainty in future projections of the global carbon cycle, amounting to about 20% of the oceanic uptake.

  16. Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 2. Modeling carbon sources, sinks, and δ13C evolution

    USGS Publications Warehouse

    McMahon, Peter B.; Chapelle, Francis H.

    1991-01-01

    Stable isotope data for dissolved inorganic carbon (DIC), carbonate shell material and cements, and microbial CO2 were combined with organic and inorganic chemical data from aquifer and confining-bed pore waters to construct geochemical reaction models along a flowpath in the Black Creek aquifer of South Carolina. Carbon-isotope fractionation between DIC and precipitating cements was treated as a Rayleigh distillation process. Organic matter oxidation was coupled to microbial fermentation and sulfate reduction. All reaction models reproduced the observed chemical and isotopic compositions of final waters. However, model 1, in which all sources of carbon and electron-acceptors were assumed to be internal to the aquifer, was invalidated owing to the large ratio of fermentation CO2 to respiration CO2 predicted by the model (5–49) compared with measured ratios (two or less). In model 2, this ratio was reduced by assuming that confining beds adjacent to the aquifer act as sources of dissolved organic carbon and sulfate. This assumption was based on measured high concentrations of dissolved organic acids and sulfate in confining-bed pore waters (60–100 μM and 100–380 μM, respectively) relative to aquifer pore waters (from less than 30 μM and 2–80 μM, respectively). Sodium was chosen as the companion ion to organic-acid and sulfate transport from confining beds because it is the predominant cation in confining-bed pore waters. As a result, excessive amounts of Na-for-Ca ion exchange and calcite precipitation (three to four times more cement than observed in the aquifer) were required by model 2 to achieve mass and isotope balance of final water. For this reason, model 2 was invalidated. Agreement between model-predicted and measured amounts of carbonate cement and ratios of fermentation CO2 to respiration CO2 were obtained in a reaction model that assumed confining beds act as sources of DIC, as well as organic acids and sulfate. This assumption was supported

  17. Methods for Introducing Inorganic Polymer Concepts throughout the Undergraduate Curriculum

    ERIC Educational Resources Information Center

    de Lill, Daniel T.; Carraher, Charles E., Jr.

    2017-01-01

    Inorganic polymers can be introduced in a variety of undergraduate courses to discuss concepts related to polymer chemistry. Inorganic polymers such as silicates and polysiloxanes are simple materials that can be incorporated into an introductory or descriptive inorganic course. Polymers based on inorganic carbon, including diamond and graphite,…

  18. Forest canopy uptake of atmospheric nitrogen deposition at eastern U.S. conifer sites: Carbon storage implications?

    Treesearch

    Herman Sievering; Ivan Fernandez; John Lee; John Hom; Lindsey Rustad

    2000-01-01

    Dry deposition determinations, along with wet deposition and throughfall (TF) measurements, at a spruce fir forest in central Maine were used to estimate the effect of atmospherically deposited nitrogen (N) uptake on forest carbon storage. Using nitric acid and particulate N as well as TF ammonium and nitrate data, the growing season (May-October) net canopy uptake of...

  19. Competition between autotrophic and heterotrophic microbial plankton for inorganic nutrients induced by variability in estuarine biophysicochemical conditions

    NASA Astrophysics Data System (ADS)

    Williams, A.; Quigg, A.

    2016-02-01

    Competition for inorganic nutrients between autotrophic and heterotrophic fractions of microbial plankton (0.2-20μm) was investigated at two stations in a sub-tropical estuary, Galveston Bay, Texas. Competition potential between these groups is enhanced because individuals are similar in size, reducing variability among their nutrient uptake efficiencies. Further, in estuaries, allochthonous supplements to autochthonous carbon may satisfy heterotrophic requirements, allowing alternative factors to limit abundance. The relative abundance of autotrophs and heterotrophs stained with SYBR Green I and enumerated on a Beckman Coulter Gallios flow cytometer were evaluated monthly during a year-long study. Shifts in the relative in situ abundance were significantly related to temperature, dissolved inorganic nitrogen (DIN), phosphorous (Pi), and total organic carbon (TOC) concentrations revealing opposing gradients of limitation by different abiotic factors. In corresponding in vitro nutrient enrichment bioassays the relative contribution of autotrophic or heterotrophic microbial plankton to significant enrichment responses varied. Only during macro- (>20μm) phytoplankton blooms do autotrophic microbial plankton respond to nutrient enrichment. Contrastingly, the heterotrophic microbial plankton responded to nutrient enrichment primarily when temperature limitation was alleviated. Therefore, the potential for autotrophic and heterotrophic microbial plankton competition for limiting nutrients is highest when autotrophic microbial plankton are also competing with larger phytoplankton during bloom events. Based on this evidence, we hypothesize that the autotrophic microbial fraction has a competitive advantage over the heterotrophs for inorganic nutrients in Galveston Bay. The observed microbial competition during estuarine phytoplankton blooms may have important consequences on biogeochemical processes including carbon and nutrient cycling.

  20. High dark inorganic carbon fixation rates by specific microbial groups in the Atlantic off the Galician coast (NW Iberian margin).

    PubMed

    Guerrero-Feijóo, Elisa; Sintes, Eva; Herndl, Gerhard J; Varela, Marta M

    2018-02-01

    Bulk dark dissolved inorganic carbon (DIC) fixation rates were determined and compared to microbial heterotrophic production in subsurface, meso- and bathypelagic Atlantic waters off the Galician coast (NW Iberian margin). DIC fixation rates were slightly higher than heterotrophic production throughout the water column, however, more prominently in the bathypelagic waters. Microautoradiography combined with catalyzed reporter deposition fluorescence in situ hybridization (MICRO-CARD-FISH) allowed us to identify several microbial groups involved in dark DIC uptake. The contribution of SAR406 (Marinimicrobia), SAR324 (Deltaproteobacteria) and Alteromonas (Gammaproteobacteria) to the dark DIC fixation was significantly higher than that of SAR202 (Chloroflexi) and Thaumarchaeota, in agreement with their contribution to microbial abundance. Q-PCR on the gene encoding for the ammonia monooxygenase subunit A (amoA) from the putatively high versus low ammonia concentration ecotypes revealed their depth-stratified distribution pattern. Taken together, our results indicate that chemoautotrophy is widespread among microbes in the dark ocean, particularly in bathypelagic waters. This chemolithoautotrophic biomass production in the dark ocean, depleted in bio-available organic matter, might play a substantial role in sustaining the dark ocean's food web. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Sources and Dynamics of Inorganic Carbon within the Upper Reaches of the Xi River Basin, Southwest China

    PubMed Central

    Zou, Junyu

    2016-01-01

    The carbon isotopic composition (δ13C) of dissolved and particulate inorganic carbon (DIC; PIC) was used to compare and analyze the origin, dynamics and evolution of inorganic carbon in two headwater tributaries of the Xi River, Southwest China. Carbonate dissolution and soil CO2 were regarded as the primary sources of DIC on the basis of δ13CDIC values which varied along the Nanpan and Beipan Rivers, from −13.9‰ to 8.1‰. Spatial trends in DIC differed between the two rivers (i.e., the tributaries), in part because factors controlling pCO2, which strongly affected carbonate dissolution, differed between the two river basins. Transport of soil CO2 and organic carbon through hydrologic conduits predominately controlled the levels of pCO2 in the Nanpan River. However, pCO2 along the upper reaches of the Nanpan River also was controlled by the extent of urbanization and industrialization relative to agriculture. DIC concentrations in the highly urbanized upper reaches of the Nanpan River were typical higher than in other carbonate-dominated areas of the upper Xi River. Within the Beipan River, the oxidation of organic carbon is the primary process that maintains pCO2 levels. The pCO2 within the Beipan River was more affected by sulfuric acid from coal industries, inputs from a scenic spot, and groundwater than along the Nanpan River. With regards to PIC, the contents and δ13C values in the Nanpan River were generally lower than those in the Beipan River, indicating that chemical and physical weathering contributes more marine carbonate detritus to the PIC along the Beipan River. The CO2 evasion flux from the Nanpan River was higher than that in the Beipan River, and generally higher than along the middle and lower reaches of the Xi River, demonstrating that the Nanpan River is an important net source of atmospheric CO2 in Southwest China. PMID:27513939

  2. Effects of dew deposition on transpiration and carbon uptake in leaves

    NASA Astrophysics Data System (ADS)

    Gerlein-Safdi, C.; Koohafkan, M.; Chung, M.; Rockwell, F. E.; Thompson, S. E.; Caylor, K. K.

    2017-12-01

    Dew deposition occurs in ecosystems worldwide, even in the driest deserts and in times of drought. Although some species absorb dew water directly via foliar uptake, a ubiquitous effect of dew on plant water balance is the interference of dew droplets with the leaf energy balance, which increases leaf albedo and emissivity and decreases leaf temperature through dew evaporation. Dew deposition frequency and amount are expected to be affected by changing environmental conditions, with unknown consequences for plant water stress and ecosystem carbon, water and energy fluxes. Here we present a simple leaf energy balance that characterizes the effect of deposition and the evaporation of dew on leaf energy balance, transpiration, and carbon uptake. The model is driven by five common meteorological variables and shows very good agreement with leaf wetness sensor data from the Blue Oak Ranch Reserve in California. We explore the tradeoffs between energy, water, and carbon balances for leaves of different sizes across a range of relative humidity, wind speed, and air temperature conditions. Our results show significant water savings from transpiration suppression up to 30% for leaf characteristic lengths of 50 cm due to the decrease in leaf temperature. C. 25% of water savings from transpiration suppression in smaller leaves arise from the effect of dew droplets on leaf albedo. CO2 assimilation is decreased by up to 15% by the presence of dew, except for bigger leaves in windspeed conditions below 1 m/s when an increase in assimilation is expected.

  3. Shallow Remineralization in the Sargasso Sea Estimated from Seasonal Variations in Oxygen and Dissolved Inorganic Carbon

    NASA Technical Reports Server (NTRS)

    Ono, S.; Ennyu, A.; Najjar, R. G.; Bates, N.

    1998-01-01

    A diagnostic model of the mean annual cycles of dissolved inorganic carbon (DIC) and oxygen below the mixed layer at the Bermuda Atlantic Time-series Study (BATS) site is presented and used to estimate organic carbon remineralization in the seasonal thermocline. The model includes lateral and vertical advection as well as vertical, diffusion. Very good agreement is found for the remineralization estimates based on oxygen and DIC. Net remineralization averaged from mid-spring to early fall is found to be a maximum between 120 and 140 in. Remineralization integrated between 100 (the compensation depth) and 250 m during this period is estimated to be about 1 mol C/sq m. This flux is consistent with independent estimates of the loss of particulate and dissolved organic carbon.

  4. Formation of "Chemically Pure" Magnetite from Mg-Fe-Carbonates Implications for the Exclusively Inorganic Origin of Magnetite and Sulfides in Martian Meteorite ALH84001

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, Douglas W.; Lauer, H. V., Jr.; Morris, R. V.; Trieman, A. H.; McKay, G. A.

    2006-01-01

    Magnetite and sulfides in the black rims of carbonate globules in Martian meteorite ALH84001 have been studied extensively because of the claim by McKay et al. that they are biogenic in origin. However, exclusively inorganic (abiotic) processes are able to account for the occurrence of carbonate-sulfide-magnetite assemblages in the meteorite. We have previously precipitated chemically zoned and sulfide-bearing carbonate globules analogous to those in ALH84001 (at less than or equal to 150 C) from multiple fluxes of variable-composition Ca-Mg-Fe-CO2-S-H2O solutions. Brief heating of precipitated globules to approx. 470 C produced magnetite and pyrrhotite within the globules by thermal decomposition of siderite and pyrite, respectively. We have also shown that morphology of magnetite formed by inorganic thermal decomposition of Fe-rich carbonate is similar to the morphology of so-called biogenic magnetite in the carbonate globules of ALH84001. Magnetite crystals in the rims of carbonate globules in ALH84001 are chemically pure [Note: "Chemically pure" is defined here as magnetite with Mg at levels comparable or lower than Mg detected by [8] in ALH84001 magnetite]. A debate continues on whether or not chemically pure magnetite can form by the thermal decomposition of mixed Mg-Fe-carbonates that have formed under abiotic conditions. Thomas-Keprta et al. argue that it is not possible to form Mg-free magnetite from Mg-Fe-carbonate based on thermodynamic data. We previously suggested that chemically pure magnetite could form by the thermal decomposition of relatively pure siderite in the outer rims of the globules. Mg-Fe-carbonates may also thermally decompose under conditions conducive for formation of chemically pure magnetite. In this paper we show through laboratory experiments that chemically pure magnetite can form by an inorganic process from mixed Mg-Fe-carbonates.

  5. Simultaneous quantum yield measurements of carbon uptake and oxygen evolution in microalgal cultures

    PubMed Central

    Gholami, Pardis; Kline, David I.; DuPont, Christopher L.; Dickson, Andrew G.; Mendola, Dominick; Martz, Todd; Allen, Andrew E.; Mitchell, B. Greg

    2018-01-01

    The photosynthetic quantum yield (Φ), defined as carbon fixed or oxygen evolved per unit of light absorbed, is a fundamental but rarely determined biophysical parameter. A method to estimate Φ for both net carbon uptake and net oxygen evolution simultaneously can provide important insights into energy and mass fluxes. Here we present details for a novel system that allows quantification of carbon fluxes using pH oscillation and simultaneous oxygen fluxes by integration with a membrane inlet mass spectrometer. The pHOS system was validated using Phaeodactylum tricornutum cultured with continuous illumination of 110 μmole quanta m-2 s-1 at 25°C. Furthermore, simultaneous measurements of carbon and oxygen flux using the pHOS-MIMS and photon flux based on spectral absorption were carried out to explore the kinetics of Φ in P. tricornutum during its acclimation from low to high light (110 to 750 μmole quanta m-2 s-1). Comparing results at 0 and 24 hours, we observed strong decreases in cellular chlorophyll a (0.58 to 0.21 pg cell-1), Fv/Fm (0.71 to 0.59) and maximum ΦCO2 (0.019 to 0.004) and ΦO2 (0.028 to 0.007), confirming the transition toward high light acclimation. The Φ time-series indicated a non-synchronized acclimation response between carbon uptake and oxygen evolution, which has been previously inferred based on transcriptomic changes for a similar experimental design with the same diatom that lacked physiological data. The integrated pHOS-MIMS system can provide simultaneous carbon and oxygen measurements accurately, and at the time-resolution required to resolve high-resolution carbon and oxygen physiological dynamics. PMID:29920568

  6. Current and Future Decadal Trends in the Oceanic Carbon Uptake Are Dominated by Internal Variability

    NASA Astrophysics Data System (ADS)

    Li, Hongmei; Ilyina, Tatiana

    2018-01-01

    We investigate the internal decadal variability of the ocean carbon uptake using 100 ensemble simulations based on the Max Planck Institute Earth system model (MPI-ESM). We find that on decadal time scales, internal variability (ensemble spread) is as large as the forced temporal variability (ensemble mean), and the largest internal variability is found in major carbon sink regions, that is, the 50-65°S band of the Southern Ocean, the North Pacific, and the North Atlantic. The MPI-ESM ensemble produces both positive and negative 10 year trends in the ocean carbon uptake in agreement with observational estimates. Negative decadal trends are projected to occur in the future under RCP4.5 scenario. Due to the large internal variability, the Southern Ocean and the North Pacific require the most ensemble members (more than 53 and 46, respectively) to reproduce the forced decadal trends. This number increases up to 79 in future decades as CO2 emission trajectory changes.

  7. Preferential uptake of soil nitrogen forms by grassland plant species.

    PubMed

    Weigelt, Alexandra; Bol, Roland; Bardgett, Richard D

    2005-02-01

    In this study, we assessed whether a range of temperate grassland species showed preferential uptake for different chemical forms of N, including inorganic N and a range of amino acids that commonly occur in temperate grassland soil. Preferential uptake of dual-labelled (13C and 15N) glycine, serine, arginine and phenylalanine, as compared to inorganic N, was tested using plants growing in pots with natural field soil. We selected five grass species representing a gradient from fertilised, productive pastures to extensive, low productivity pastures (Lolium perenne, Holcus lanatus, Anthoxanthum odoratum, Deschampsia flexuosa, and Nardus stricta). Our data show that all grass species were able to take up directly a diversity of soil amino acids of varying complexity. Moreover, we present evidence of marked inter-species differences in preferential use of chemical forms of N of varying complexity. L. perenne was relatively more effective at using inorganic N and glycine compared to the most complex amino acid phenylalanine, whereas N. stricta showed a significant preference for serine over inorganic N. Total plant N acquisition, measured as root and shoot concentration of labelled compounds, also revealed pronounced inter-species differences which were related to plant growth rate: plants with higher biomass production were found to take up more inorganic N. Our findings indicate that species-specific differences in direct uptake of different N forms combined with total N acquisition could explain changes in competitive dominance of grass species in grasslands of differing fertility.

  8. [Biogeochemical processes of the major ions and dissolved inorganic carbon in the Guijiang River].

    PubMed

    Tang, Wen-Kui; Tao, Zhen; Gao, Quan-Zhou; Mao, Hai-Ruo; Jiang, Guang-Hui; Jiao, Shu-Lin; Zheng, Xiong-Bo; Zhang, Qian-Zhu; Ma, Zan-Wen

    2014-06-01

    Within the drainage basin, information about natural processes and human activities can be recorded in the chemical composition of riverine water. The analysis of the Guijiang River, the first level tributary of the Xijiang River, demonstrated that the chemical composition of water in the Guijiang River was mainly influenced by the chemical weathering of carbonate rocks within the drainage basin, in which CO2 was the main erosion medium, and that the weathering of carbonate rock by H2SO4 had a remarkable impact on the water chemical composition in the Guijiang River. Precipitation, human activities, the weathering of carbonate rocks and silicate rocks accounted for 2.7%, 6.3%, 72.8% and 18.2% of the total dissolved load, respectively. The stable isotopic compositions of dissolved inorganic carbon (delta13C(DIC)) indicated that DIC in the Guijiang River had been assimilated by the phytoplankton in photosynthesis. The primary production of phytoplankton contributed to 22.3%-30.9% of particulate organic carbon (POC) in the Guijiang River, which implies that phytoplankton can transform DIC into POC by photosynthesis, and parts of POC will sink into the bottom of the river in transit, which leads into the formation of burial organic carbon.

  9. Warmer temperatures reduce net carbon uptake, but do not affect water use, in a mature southern Appalachian forest

    Treesearch

    A. Christopher Oishi; Chelcy F. Miniat; Kimberly A. Novick; Steven T. Brantley; James M. Vose; John T. Walker

    2018-01-01

    Increasing air temperature is expected to extend growing season length in temperate, broadleaf forests, leading to potential increases in evapotranspiration and net carbon uptake. However, other key processes affecting water and carbon cycles are also highly temperature-dependent. Warmer temperatures may result in higher ecosystem carbon loss through...

  10. Inorganic nanotubes and fullerene-like materials.

    PubMed

    Tenne, Reshef

    2002-12-02

    Following the discovery of fullerenes and carbon nanotubes, it was shown that nanoparticles of inorganic layered compounds, like MoS2, are unstable in the planar form and they form closed cage structures with polyhedral or nanotubular shapes. Various issues on the structure, synthesis, and properties of such inorganic fullerene-like structures are reviewed, together with some possible applications.

  11. Thin-film versus slurry-phase carbonation of steel slag: CO₂ uptake and effects on mineralogy.

    PubMed

    Baciocchi, R; Costa, G; Di Gianfilippo, M; Polettini, A; Pomi, R; Stramazzo, A

    2015-01-01

    The results of direct aqueous accelerated carbonation of three types of steel manufacturing residues, including an electric arc furnace (EAF) slag and two basic oxygen furnace (BOF) slags, are reported. Batch accelerated carbonation tests were conducted at different temperatures and CO2 pressures applying the thin-film route (liquid to solid, L/S, ratio=0.3L/kg) or the slurry-phase route (L/S ratio=5L/kg). The CO2 uptake strongly depended on both the slag characteristics and the process route; maximum yields of 280 (EAF), 325 (BOF1) and 403 (BOF2) gCO2/kg slag were achieved in slurry phase at T=100°C and pCO2=10 bar. Differently from previous studies, additional carbonates (other than Ca-based phases) were retrieved in the carbonated BOF slags, indicating that also Mg-, Fe- and Mn-containing phases partially reacted with CO2 under the tested conditions. The results hence show that the effects of accelerated carbonation in terms of CO2 uptake capacity, yield of mineral conversion into carbonates and mineralogy of the treated product, strongly rely on several factors. These include, above all, the mineralogy of the original material and the operating conditions adopted, which thus need specific case-by-case optimization to maximize the CO2 sequestration yield. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Switching predominance of organic versus inorganic carbon exports from an intermediate-size subarctic watershed

    USGS Publications Warehouse

    Dornblaser, Mark M.; Striegl, Robert G.

    2015-01-01

    Hydrologic exports of dissolved inorganic and organic carbon (DIC, DOC) reflect permafrost conditions in arctic and subarctic river basins. DIC yields in particular, increase with decreased permafrost extent. We investigated the influence of permafrost extent on DIC and DOC yield in a tributary of the Yukon River, where the upper watershed has continuous permafrost and the lower watershed has discontinuous permafrost. Our results indicate that DIC versus DOC predominance switches with interannual changes in water availability and flow routing in intermediate-size watersheds having mixed permafrost coverage. Large water yield and small concentrations from mountainous headwaters and small water yield and high concentrations from lowlands produced similar upstream and downstream carbon yields. However, DOC export exceeded DIC export during high-flow 2011 while DIC predominated during low-flow 2010. The majority of exported carbon derived from near-surface organic sources when landscapes were wet or frozen and from mineralized subsurface sources when infiltration increased.

  13. Spatial patterns of ecosystem carbon residence time and NPP-driven carbon uptake in the conterminous United States

    NASA Astrophysics Data System (ADS)

    Zhou, Tao; Luo, Yiqi

    2008-09-01

    Ecosystem carbon (C) uptake is determined largely by C residence times and increases in net primary production (NPP). Therefore, evaluation of C uptake at a regional scale requires knowledge on spatial patterns of both residence times and NPP increases. In this study, we first applied an inverse modeling method to estimate spatial patterns of C residence times in the conterminous United States. Then we combined the spatial patterns of estimated residence times with a NPP change trend to assess the spatial patterns of regional C uptake in the United States. The inverse analysis was done by using the genetic algorithm and was based on 12 observed data sets of C pools and fluxes. Residence times were estimated by minimizing the total deviation between modeled and observed values. Our results showed that the estimated C residence times were highly heterogeneous over the conterminous United States, with most of the regions having values between 15 and 65 years; and the averaged C residence time was 46 years. The estimated C uptake for the whole conterminous United States was 0.15 P g C a-1. Large portions of the taken C were stored in soil for grassland and cropland (47-70%) but in plant pools for forests and woodlands (73-82%). The proportion of C uptake in soil was found to be determined primarily by C residence times and be independent of the magnitude of NPP increase. Therefore, accurate estimation of spatial patterns of C residence times is crucial for the evaluation of terrestrial ecosystem C uptake.

  14. Impact of seawater carbonate chemistry on the calcification of marine bivalves

    NASA Astrophysics Data System (ADS)

    Thomsen, J.; Haynert, K.; Wegner, K. M.; Melzner, F.

    2015-07-01

    Bivalve calcification, particularly of the early larval stages, is highly sensitive to the change in ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32-] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no effects and [HCO3-] and pH had only limited effects on shell growth, while lowered [CO32-] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32-], indicating that [HCO3-] rather than [CO32-] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32-] it is not possible to differentiate between these under natural seawater conditions. An equivalent of about 80 μmol kg-1 [CO32-] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the mechanisms that limit or facilitate adaptation to future ocean acidification, it is necessary to better

  15. Impact of seawater carbonate chemistry on the calcification of marine bivalves

    NASA Astrophysics Data System (ADS)

    Thomsen, J.; Haynert, K.; Wegner, K. M.; Melzner, F.

    2015-01-01

    Bivalve calcification, particular of the early larval stages is highly sensitive to the change of ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32-] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no and [HCO3-] and pH only limited effects on shell growth, while lowered [CO32-] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32-], indicating that [HCO3-] rather than [CO32-] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32-] it is not possible to differentiate between these under natural seawater conditions. Therefore, the availability of [HCO3-] combined with favorable environmental pH determines calcification rate and an equivalent of about 80 μmol kg-1 [CO32-] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the

  16. BILP-19-An Ultramicroporous Organic Network with Exceptional Carbon Dioxide Uptake.

    PubMed

    Klumpen, Christoph; Radakovitsch, Florian; Jess, Andreas; Senker, Jürgen

    2017-08-12

    Porous benzimidazole-based polymers (BILPs) have proven to be promising for carbon dioxide capture and storage. The polarity of their chemical structure in combination with an inherent porosity allows for adsorbing large amounts of carbon dioxide in combination with high selectivities over unpolar guest molecules such as methane and nitrogen. For this reason, among purely organic polymers, BILPs contain some of the most effective networks to date. Nevertheless, they are still outperformed by competitive materials such as metal-organic frameworks (MOFs) or metal doped porous polymers. Here, we report the synthesis of BILP-19 and its exceptional carbon dioxide uptake of up to 6 mmol•g-1 at 273 K, making the network comparable to state-of-the-art materials. BILP-19 precipitates in a particulate structure with a strongly anisotropic growth into platelets, indicating a sheet-like structure for the network. It exhibits only a small microporous but a remarkable ultra-microporous surface area of 144 m2•g-1 and 1325 m2•g-1, respectively. We attribute the exceptional uptake of small guest molecules such as carbon dioxide and water to the distinct ultra-microporosity. Additionally, a pronounced hysteresis for both guests is observed, which in combination with the platelet character is probably caused by an expansion of the interparticle space, creating additional accessible ultra-microporous pore volume. For nitrogen and methane, this effect does not occur which explains their low affinity. In consequence, Henry selectivities of 123 for CO2/N2 at 298 K and 12 for CO2/CH4 at 273 K were determined. The network was carefully characterized with solid-state nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy, thermal gravimetry (TG) and elemental analyses as well as physisorption experiments with Ar, N2, CO2, CH4 and water.

  17. The pitcher plant Sarracenia purpurea can directly acquire organic nitrogen and short-circuit the inorganic nitrogen cycle.

    PubMed

    Karagatzides, Jim D; Butler, Jessica L; Ellison, Aaron M

    2009-07-07

    Despite the large stocks of organic nitrogen in soil, nitrogen availability limits plant growth in many terrestrial ecosystems because most plants take up only inorganic nitrogen, not organic nitrogen. Although some vascular plants can assimilate organic nitrogen directly, only recently has organic nitrogen been found to contribute significantly to the nutrient budget of any plant. Carnivorous plants grow in extremely nutrient-poor environments and carnivory has evolved in these plants as an alternative pathway for obtaining nutrients. We tested if the carnivorous pitcher plant Sarracenia purpurea could directly take up intact amino acids in the field and compared uptake of organic and inorganic forms of nitrogen across a gradient of nitrogen deposition. We hypothesized that the contribution of organic nitrogen to the nitrogen budget of the pitcher plant would decline with increasing nitrogen deposition. At sites in Canada (low nitrogen deposition) and the United States (high nitrogen deposition), individual pitchers were fed two amino acids, glycine and phenylalanine, and inorganic nitrogen (as ammonium nitrate), individually and in mixture. Plants took up intact amino acids. Acquisition of each form of nitrogen provided in isolation exceeded uptake of the same form in mixture. At the high deposition site, uptake of organic nitrogen was higher than uptake of inorganic nitrogen. At the low deposition site, uptake of all three forms of nitrogen was similar. Completeness of the associated detritus-based food web that inhabits pitcher-plant leaves and breaks down captured prey had no effect on nitrogen uptake. By taking up intact amino acids, Sarracenia purpurea can short-circuit the inorganic nitrogen cycle, thus minimizing potential bottlenecks in nitrogen availability that result from the plant's reliance for nitrogen mineralization on a seasonally reconstructed food web operating on infrequent and irregular prey capture.

  18. The Pitcher Plant Sarracenia purpurea Can Directly Acquire Organic Nitrogen and Short-Circuit the Inorganic Nitrogen Cycle

    PubMed Central

    Karagatzides, Jim D.; Butler, Jessica L.; Ellison, Aaron M.

    2009-01-01

    Background Despite the large stocks of organic nitrogen in soil, nitrogen availability limits plant growth in many terrestrial ecosystems because most plants take up only inorganic nitrogen, not organic nitrogen. Although some vascular plants can assimilate organic nitrogen directly, only recently has organic nitrogen been found to contribute significantly to the nutrient budget of any plant. Carnivorous plants grow in extremely nutrient-poor environments and carnivory has evolved in these plants as an alternative pathway for obtaining nutrients. We tested if the carnivorous pitcher plant Sarracenia purpurea could directly take up intact amino acids in the field and compared uptake of organic and inorganic forms of nitrogen across a gradient of nitrogen deposition. We hypothesized that the contribution of organic nitrogen to the nitrogen budget of the pitcher plant would decline with increasing nitrogen deposition. Methodology and Principal Findings At sites in Canada (low nitrogen deposition) and the United States (high nitrogen deposition), individual pitchers were fed two amino acids, glycine and phenylalanine, and inorganic nitrogen (as ammonium nitrate), individually and in mixture. Plants took up intact amino acids. Acquisition of each form of nitrogen provided in isolation exceeded uptake of the same form in mixture. At the high deposition site, uptake of organic nitrogen was higher than uptake of inorganic nitrogen. At the low deposition site, uptake of all three forms of nitrogen was similar. Completeness of the associated detritus-based food web that inhabits pitcher-plant leaves and breaks down captured prey had no effect on nitrogen uptake. Conclusions and Significance By taking up intact amino acids, Sarracenia purpurea can short-circuit the inorganic nitrogen cycle, thus minimizing potential bottlenecks in nitrogen availability that result from the plant's reliance for nitrogen mineralization on a seasonally reconstructed food web operating on

  19. Influence of water management and natural variability on dissolved inorganic carbon dynamics in a mangrove-dominated estuary.

    PubMed

    Volta, Chiara; Ho, David T; Friederich, Gernot; Engel, Victor C; Bhat, Mahadev

    2018-09-01

    High-resolution time series measurements of temperature, salinity, pH and pCO 2 were made during the period October 2014-September 2015 at the midpoint of Shark River, a 15km tidal river that originates in the freshwater Everglades of south Florida (USA) and discharges into the Gulf of Mexico. Dissolved inorganic carbon dynamics in this system vary over time, and during this study could be classified into three distinct regimes corresponding to October 2014-February 2015 (a wet to dry season transition period), March-May 2015 (dry period) and July-September 2015 (wet period). Average net longitudinal dissolved inorganic carbon (DIC) fluxes and air-water CO 2 fluxes from the Shark River estuary were determined for the three periods. Net DIC fluxes to the coast were estimated to vary between 23.2 and 25.4×10 5 mold -1 with an average daily DIC flux of 24.3×10 5 mold -1 during the year of study. CO 2 emissions ranged between 5.5 and 7.8×10 5 mold -1 with an average daily value of 6.4×10 5 mold -1 during the year. The differences in estuarine carbon fluxes during the study period are attributed to differences in the relative importance of hydro-climatological drivers. Results suggest that, during months characterized by reduced rainfall, carbon fluxes are affected by water management via control structures in the upstream Everglades marshes. During months with high rainfall, when culverts are closed and rainfall events are more frequent, carbon fluxes depend more on other forcings, such as rainfall and groundwater discharge. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Tracking the autochthonous carbon transfer in stream biofilm food webs.

    PubMed

    Risse-Buhl, Ute; Trefzger, Nicolai; Seifert, Anne-Gret; Schönborn, Wilfried; Gleixner, Gerd; Küsel, Kirsten

    2012-01-01

    Food webs in the rhithral zone rely mainly on allochthonous carbon from the riparian vegetation. However, autochthonous carbon might be more important in open canopy streams. In streams, most of the microbial activity occurs in biofilms, associated with the streambed. We followed the autochthonous carbon transfer toward bacteria and grazing protozoa within a stream biofilm food web. Biofilms that developed in a second-order stream (Thuringia, Germany) were incubated in flow channels under climate-controlled conditions. Six-week-old biofilms received either ¹³C- or ¹²C-labeled CO₂, and uptake into phospholipid fatty acids was followed. The dissolved inorganic carbon of the flow channel water became immediately labeled. In biofilms grown under 8-h light/16-h dark conditions, more than 50% of the labeled carbon was incorporated in biofilm algae, mainly filamentous cyanobacteria, pennate diatoms, and nonfilamentous green algae. A mean of 29% of the labeled carbon reached protozoan grazer. The testate amoeba Pseudodifflugia horrida was highly abundant in biofilms and seemed to be the most important grazer on biofilm bacteria and algae. Hence, stream biofilms dominated by cyanobacteria and algae seem to play an important role in the uptake of CO₂ and transfer of autochthonous carbon through the microbial food web.

  1. Numerical cell model investigating cellular carbon fluxes in Emiliania huxleyi.

    PubMed

    Holtz, Lena-Maria; Wolf-Gladrow, Dieter; Thoms, Silke

    2015-01-07

    Coccolithophores play a crucial role in the marine carbon cycle and thus it is interesting to know how they will respond to climate change. After several decades of research the interplay between intracellular processes and the marine carbonate system is still not well understood. On the basis of experimental findings given in literature, a numerical cell model is developed that describes inorganic carbon fluxes between seawater and the intracellular sites of calcite precipitation and photosynthetic carbon fixation. The implemented cell model consists of four compartments, for each of which the carbonate system is resolved individually. The four compartments are connected to each other via H(+), CO2, and HCO3(-) fluxes across the compartment-confining membranes. For CO2 accumulation around RubisCO, an energy-efficient carbon concentrating mechanism is proposed that relies on diffusive CO2 uptake. At low external CO2 concentrations and high light intensities, CO2 diffusion does not suffice to cover the carbon demand of photosynthesis and an additional uptake of external HCO3(-) becomes essential. The model is constrained by data of Emiliania huxleyi, the numerically most abundant coccolithophore species in the present-day ocean. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  2. Disequilibrium δ18O values in microbial carbonates as a tracer of metabolic production of dissolved inorganic carbon

    NASA Astrophysics Data System (ADS)

    Thaler, Caroline; Millo, Christian; Ader, Magali; Chaduteau, Carine; Guyot, François; Ménez, Bénédicte

    2017-02-01

    Carbon and oxygen stable isotope compositions of carbonates are widely used to retrieve paleoenvironmental information. However, bias may exist in such reconstructions as carbonate precipitation is often associated with biological activity. Several skeleton-forming eukaryotes have been shown to precipitate carbonates with significant offsets from isotopic equilibrium with water. Although poorly understood, the origin of these biologically-induced isotopic shifts in biogenic carbonates, commonly referred to as "vital effects", could be related to metabolic effects that may not be restricted to mineralizing eukaryotes. The aim of our study was to determine whether microbially-mediated carbonate precipitation can also produce offsets from equilibrium for oxygen isotopes. We present here δ18O values of calcium carbonates formed by the activity of Sporosarcina pasteurii, a carbonatogenic bacterium whose ureolytic activity produces ammonia (thus increasing pH) and dissolved inorganic carbon (DIC) that precipitates as solid carbonates in the presence of Ca2+. We show that the 1000 lnαCaCO3-H2O values for these bacterially-precipitated carbonates are up to 24.7‰ smaller than those expected for precipitation at isotopic equilibrium. A similar experiment run in the presence of carbonic anhydrase (an enzyme able to accelerate oxygen isotope equilibration between DIC and water) resulted in δ18O values of microbial carbonates in line with values expected at isotopic equilibrium with water. These results demonstrate for the first time that bacteria can induce calcium carbonate precipitation in strong oxygen isotope disequilibrium with water, similarly to what is observed for eukaryotes. This disequilibrium effect can be unambiguously ascribed to oxygen isotope disequilibrium between DIC and water inherited from the oxygen isotope composition of the ureolytically produced CO2, probably combined with a kinetic isotope effect during CO2 hydration/hydroxylation. The fact that

  3. CONTINUOUS, AUTOMATED AND SIMULTANEOUS MEASUREMENT OF OXYGEN UPTAKE AND CARBON DIOXIDE EVOLUTION IN BIOLOGICAL SYSTEMS

    EPA Science Inventory

    Commercial respirometers are capable of continuously and automatically measuring oxygen uptake in bioreactors. A method for continuously and automatically measuring carbon dioxide evolution can be retrofitted to commercial respirometers. Continuous and automatic measurements of...

  4. A systematic investigation of the preparation and properties of composite carbon molecular sieves containing inorganic oxides

    NASA Technical Reports Server (NTRS)

    Foley, Henry C.

    1990-01-01

    The objective of this research is to define the methodology for the preparation and characterization of new carbon-based molecular sieves with composite structures. Carbon molecular sieves have found increasing application in the field of separation and purification of gases. These materials are relatively easy to prepare and their surfaces can be modified to some extent. It is expected that by combining inorganic oxides with the carbonaceous structure one can begin to design composite materials with a wider range of possible chemical and physical properties. In this way, the IOM-CMS materials may confer distinct advantages over pure carbon molecular sieves, not just for separation, but also for catalysis. The most recent results in the design and characterization of these IOM-CMS materials are reviewed and summarized. Directions for further research are also presented.

  5. Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 2. Modeling carbon sources, sinks, and δ13C evolution

    USGS Publications Warehouse

    McMahon, Peter B.; Chapelle, Francis H.

    1991-01-01

    Stable isotope data for dissolved inorganic carbon (DIC), carbonate shell material and cements, and microbial CO2 were combined with organic and inorganic chemical data from aquifer and confining-bed pore waters to construct geochemical reaction models along a flowpath in the Black Creek aquifer of South Carolina. Carbon-isotope fractionation between DIC and precipitating cements was treated as a Rayleigh distillation process. Organic matter oxidation was coupled to microbial fermentation and sulfate reduction. All reaction models reproduced the observed chemical and isotopic compositions of final waters. However, model 1, in which all sources of carbon and electron-acceptors were assumed to be internal to the aquifer, was invalidated owing to the large ratio of fermentation CO2 to respiration CO2 predicted by the model (5–49) compared with measured ratios (two or less). In model 2, this ratio was reduced by assuming that confining beds adjacent to the aquifer act as sources of dissolved organic carbon and sulfate. This assumption was based on measured high concentrations of dissolved organic acids and sulfate in confining-bed pore waters (60–100 μM and 100–380 μM, respectively) relative to aquifer pore waters (from less than 30 μM and 2–80 μM, respectively). Sodium was chosen as the companion ion to organic-acid and sulfate transport from confining beds because it is the predominant cation in confining-bed pore waters. As a result, excessive amounts of Na-for-Ca ion exchange and calcite precipitation (three to four times more cement than observed in the aquifer) were required by model 2 to achieve mass and isotope balance of final water. For this reason, model 2 was invalidated. Agreement between model-predicted and measured amounts of carbonate cement and ratios of fermentation CO2 to respiration CO2 were obtained in a reaction model that assumed confining beds act as sources of DIC, as well as organic acids and sulfate. This assumption was

  6. External inorganic N source enhances the uptake of As species in garland chrysanthemum (C. coronarium) amended with chicken manure bearing roxarsone and its metabolites.

    PubMed

    Yao, Lixian; Huang, Lianxi; He, Zhaohuan; Zhou, Changmin; Li, Guoliang; Yang, Baomei; Deng, Xiancai

    2013-06-15

    Roxarsone (ROX), a widely used feed organoarsenic additive, is excreted as itself and its metabolites in animal manure. Animal manure is commonly applied with N fertilizer to meet the N demand of crop. We investigated the accumulation of As species in garland chrysanthemum plants fertilized with chicken manure (CM) bearing ROX and its metabolites, combined with different inorganic N sources (NH₄(+), NO₃(-) and urea), respectively. The change of pH, N forms and As species in soils was examined as well. The results show that As(V), As(III) and dimethylarsinic acid (DMA) were detectable in soils, and conversions between As species were affected by three inorganic N sources, irrespective of N form and soil pH. As(III) was the sole As species in garland chrysanthemum shoots, and As(III) and As(V) could be detected in roots. Urea, superior to NH₄(+), significantly enhanced the uptake of As species in plants by promoting plant growth, while NO₃(-) slightly reduced the As accumulation due to decreased biomass. As(III) was the dominant As compound (86.9-89.7%) in plants. Therefore, inorganic N fertilizers may inadvertently increase the risk of As contamination in plant from ROX via the way ROX→chicken→CM→soil→crop. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Tradeoffs between global warming and day length on the start of the carbon uptake period in seasonally cold ecosystems.

    PubMed

    Wohlfahrt, Georg; Cremonese, Edoardo; Hammerle, Albin; Hörtnagl, Lukas; Galvagno, Marta; Gianelle, Damiano; Marcolla, Barbara; di Cella, Umberto Morra

    2013-12-16

    It is well established that warming leads to longer growing seasons in seasonally cold ecosystems. Whether this goes along with an increase in the net ecosystem carbon dioxide (CO 2 ) uptake is much more controversial. We studied the effects of warming on the start of the carbon uptake period (CUP) of three mountain grasslands situated along an elevational gradient in the Alps. To this end we used a simple empirical model of the net ecosystem CO 2 exchange, calibrated and forced with multi-year empirical data from each site. We show that reductions in the quantity and duration of daylight associated with earlier snowmelts were responsible for diminishing returns, in terms of carbon gain, from longer growing seasons caused by reductions in daytime photosynthetic uptake and increases in nighttime losses of CO 2 . This effect was less pronounced at high, compared to low, elevations, where the start of the CUP occurred closer to the summer solstice when changes in day length and incident radiation are minimal.

  8. Steady-State Growth under Inorganic Carbon Limitation Conditions Increases Energy Consumption for Maintenance and Enhances Nitrous Oxide Production in Nitrosomonas europaea.

    PubMed

    Mellbye, Brett L; Giguere, Andrew; Chaplen, Frank; Bottomley, Peter J; Sayavedra-Soto, Luis A

    2016-06-01

    Nitrosomonas europaea is a chemolithoautotrophic bacterium that oxidizes ammonia (NH3) to obtain energy for growth on carbon dioxide (CO2) and can also produce nitrous oxide (N2O), a greenhouse gas. We interrogated the growth, physiological, and transcriptome responses of N. europaea to conditions of replete (>5.2 mM) and limited inorganic carbon (IC) provided by either 1.0 mM or 0.2 mM sodium carbonate (Na2CO3) supplemented with atmospheric CO2 IC-limited cultures oxidized 25 to 58% of available NH3 to nitrite, depending on the dilution rate and Na2CO3 concentration. IC limitation resulted in a 2.3-fold increase in cellular maintenance energy requirements compared to those for NH3-limited cultures. Rates of N2O production increased 2.5- and 6.3-fold under the two IC-limited conditions, increasing the percentage of oxidized NH3-N that was transformed to N2O-N from 0.5% (replete) up to 4.4% (0.2 mM Na2CO3). Transcriptome analysis showed differential expression (P ≤ 0.05) of 488 genes (20% of inventory) between replete and IC-limited conditions, but few differences were detected between the two IC-limiting treatments. IC-limited conditions resulted in a decreased expression of ammonium/ammonia transporter and ammonia monooxygenase subunits and increased the expression of genes involved in C1 metabolism, including the genes for RuBisCO (cbb gene cluster), carbonic anhydrase, folate-linked metabolism of C1 moieties, and putative C salvage due to oxygenase activity of RuBisCO. Increased expression of nitrite reductase (gene cluster NE0924 to NE0927) correlated with increased production of N2O. Together, these data suggest that N. europaea adapts physiologically during IC-limited steady-state growth, which leads to the uncoupling of NH3 oxidation from growth and increased N2O production. Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, is an important process in the global nitrogen cycle. This process is generally dependent on ammonia

  9. Steady-State Growth under Inorganic Carbon Limitation Conditions Increases Energy Consumption for Maintenance and Enhances Nitrous Oxide Production in Nitrosomonas europaea

    PubMed Central

    Giguere, Andrew; Chaplen, Frank; Bottomley, Peter J.

    2016-01-01

    ABSTRACT Nitrosomonas europaea is a chemolithoautotrophic bacterium that oxidizes ammonia (NH3) to obtain energy for growth on carbon dioxide (CO2) and can also produce nitrous oxide (N2O), a greenhouse gas. We interrogated the growth, physiological, and transcriptome responses of N. europaea to conditions of replete (>5.2 mM) and limited inorganic carbon (IC) provided by either 1.0 mM or 0.2 mM sodium carbonate (Na2CO3) supplemented with atmospheric CO2. IC-limited cultures oxidized 25 to 58% of available NH3 to nitrite, depending on the dilution rate and Na2CO3 concentration. IC limitation resulted in a 2.3-fold increase in cellular maintenance energy requirements compared to those for NH3-limited cultures. Rates of N2O production increased 2.5- and 6.3-fold under the two IC-limited conditions, increasing the percentage of oxidized NH3-N that was transformed to N2O-N from 0.5% (replete) up to 4.4% (0.2 mM Na2CO3). Transcriptome analysis showed differential expression (P ≤ 0.05) of 488 genes (20% of inventory) between replete and IC-limited conditions, but few differences were detected between the two IC-limiting treatments. IC-limited conditions resulted in a decreased expression of ammonium/ammonia transporter and ammonia monooxygenase subunits and increased the expression of genes involved in C1 metabolism, including the genes for RuBisCO (cbb gene cluster), carbonic anhydrase, folate-linked metabolism of C1 moieties, and putative C salvage due to oxygenase activity of RuBisCO. Increased expression of nitrite reductase (gene cluster NE0924 to NE0927) correlated with increased production of N2O. Together, these data suggest that N. europaea adapts physiologically during IC-limited steady-state growth, which leads to the uncoupling of NH3 oxidation from growth and increased N2O production. IMPORTANCE Nitrification, the aerobic oxidation of ammonia to nitrate via nitrite, is an important process in the global nitrogen cycle. This process is generally dependent

  10. Carbon availability triggers fungal nitrogen uptake and transport in arbuscular mycorrhizal symbiosis

    PubMed Central

    Fellbaum, Carl R.; Gachomo, Emma W.; Beesetty, Yugandhar; Choudhari, Sulbha; Strahan, Gary D.; Pfeffer, Philip E.; Kiers, E. Toby; Bücking, Heike

    2012-01-01

    The arbuscular mycorrhizal (AM) symbiosis, formed between the majority of land plants and ubiquitous soil fungi of the phylum Glomeromycota, is responsible for massive nutrient transfer and global carbon sequestration. AM fungi take up nutrients from the soil and exchange them against photosynthetically fixed carbon (C) from the host. Recent studies have demonstrated that reciprocal reward strategies by plant and fungal partners guarantee a “fair trade” of phosphorus against C between partners [Kiers ET, et al. (2011) Science 333:880–882], but whether a similar reward mechanism also controls nitrogen (N) flux in the AM symbiosis is not known. Using mycorrhizal root organ cultures, we manipulated the C supply to the host and fungus and followed the uptake and transport of N sources in the AM symbiosis, the enzymatic activities of arginase and urease, and fungal gene expression in the extraradical and intraradical mycelium. We found that the C supply of the host plant triggers the uptake and transport of N in the symbiosis, and that the increase in N transport is orchestrated by changes in fungal gene expression. N transport in the symbiosis is stimulated only when the C is delivered by the host across the mycorrhizal interface, not when C is supplied directly to the fungal extraradical mycelium in the form of acetate. These findings support the importance of C flux from the root to the fungus as a key trigger for N uptake and transport and provide insight into the N transport regulation in the AM symbiosis. PMID:22308426

  11. Nitric oxide generated by nitrate reductase increases nitrogen uptake capacity by inducing lateral root formation and inorganic nitrogen uptake under partial nitrate nutrition in rice

    PubMed Central

    Sun, Huwei; Li, Jiao; Song, Wenjing; Tao, Jinyuan; Huang, Shuangjie; Chen, Si; Hou, Mengmeng; Xu, Guohua; Zhang, Yali

    2015-01-01

    Increasing evidence shows that partial nitrate nutrition (PNN) can be attributed to improved plant growth and nitrogen-use efficiency (NUE) in rice. Nitric oxide (NO) is a signalling molecule involved in many physiological processes during plant development and nitrogen (N) assimilation. It remains unclear whether molecular NO improves NUE through PNN. Two rice cultivars (cvs Nanguang and Elio), with high and low NUE, respectively, were used in the analysis of NO production, nitrate reductase (NR) activity, lateral root (LR) density, and 15N uptake under PNN, with or without NO production donor and inhibitors. PNN increased NO accumulation in cv. Nanguang possibly through the NIA2-dependent NR pathway. PNN-mediated NO increases contributed to LR initiation, 15NH4 +/15NO3 – influx into the root, and levels of ammonium and nitrate transporters in cv. Nanguang but not cv. Elio. Further results revealed marked and specific induction of LR initiation and 15NH4 +/15NO3 – influx into the roots of plants supplied with NH4 ++sodium nitroprusside (SNP) relative to those supplied with NH4 + alone, and considerable inhibition upon the application of cPTIO or tungstate (NR inhibitor) in addition to PNN, which is in agreement with the change in NO fluorescence in the two rice cultivars. The findings suggest that NO generated by the NR pathway plays a pivotal role in improving the N acquisition capacity by increasing LR initiation and the inorganic N uptake rate, which may represent a strategy for rice plants to adapt to a fluctuating nitrate supply and increase NUE. PMID:25784715

  12. Physiologically Based Pharmacokinetic Model for Long-Circulating Inorganic Nanoparticles.

    PubMed

    Liang, Xiaowen; Wang, Haolu; Grice, Jeffrey E; Li, Li; Liu, Xin; Xu, Zhi Ping; Roberts, Michael S

    2016-02-10

    A physiologically based pharmacokinetic model was developed for accurately characterizing and predicting the in vivo fate of long-circulating inorganic nanoparticles (NPs). This model is built based on direct visualization of NP disposition details at the organ and cellular level. It was validated with multiple data sets, indicating robust inter-route and interspecies predictive capability. We suggest that the biodistribution of long-circulating inorganic NPs is determined by the uptake and release of NPs by phagocytic cells in target organs.

  13. Stable carbon isotope signals in particulate organic and inorganic carbon of coccolithophores - A numerical model study for Emiliania huxleyi.

    PubMed

    Holtz, Lena-Maria; Wolf-Gladrow, Dieter; Thoms, Silke

    2017-05-07

    A recent numerical cell model, which explains observed light and carbonate system effects on particulate organic and inorganic carbon (POC and PIC) production rates under the assumption of internal pH homeostasis, is extended for stable carbon isotopes ( 12 C, 13 C). Aim of the present study is to mechanistically understand the stable carbon isotopic fractionation signal (ε) in POC and PIC and furthermore the vital effect(s) included in measured ε PIC values. The virtual cell is divided into four compartments, for each of which the 12 C as well as the 13 C carbonate system kinetics are implemented. The compartments are connected to each other via trans-membrane fluxes. In contrast to existing carbon fractionation models, the presented model calculates the disequilibrium state for both carbonate systems and for each compartment. It furthermore calculates POC and PIC production rates as well as ε POC and ε PIC as a function of given light conditions and the compositions of the external carbonate system. Measured POC and PIC production rates as well as ε PIC values are reproduced well by the model (comparison with literature data). The observed light effect on ε POC (increase of ε POC with increasing light intensities), however, is not reproduced by the basic model set-up, which is solely based on RubisCO fractionation. When extending the latter set-up by assuming that biological fractionation includes further carbon fractionation steps besides the one of RubisCO, the observed light effect on ε POC is also reproduced. By means of the extended model version, four different vital effects that superimpose each other in a real cell can be detected. Finally, we discuss potential limitations of the ε PIC proxy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery

    NASA Astrophysics Data System (ADS)

    Smith, Bryan Ronain; Ghosn, Eliver Eid Bou; Rallapalli, Harikrishna; Prescher, Jennifer A.; Larson, Timothy; Herzenberg, Leonore A.; Gambhir, Sanjiv Sam

    2014-06-01

    In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using `bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6Chi monocytes (almost 100% uptake in Ly-6Chi monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.

  15. The mycorrhizal type governs root exudation and nitrogen uptake of temperate tree species.

    PubMed

    Liese, Rebecca; Lübbe, Torben; Albers, Nora W; Meier, Ina C

    2018-01-01

    Even though the two dominant mycorrhizal associations of temperate tree species differentially couple carbon (C) and nitrogen (N) cycles in temperate forests, systematic differences between the biogeochemical cycles of arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) tree species remain poorly described. A classification according to the mycorrhizal type offers the chance, though, to develop a global frame concept for the prediction of temperate ecosystem responses to environmental change. Focusing on the influence of mycorrhizal types on two key plant processes of biogeochemical cycling (root exudation and N acquisition), we investigated four temperate deciduous tree species per mycorrhizal type in a drought experiment in large mesocosms. We hypothesized that (H1) C loss by root exudation is higher in ECM than in AM trees, (H2) drought leads to higher reductions in root exudation of drought-sensitive ECM trees and (H3) inorganic N uptake is higher in AM than in ECM trees. In contradiction to H2, we found no systematic difference in root exudation between the mycorrhizal types at ample soil moisture, but almost twofold higher exudation in ECM trees when exposed to soil drought. In addition, photosynthetic C cost of root exudation strongly increased by ~10-fold in drought-treated ECM trees, while it only doubled in AM trees, which confirms H1. With respect to H3, we corroborated that AM trees had higher absolute and relative inorganic N acquisition rates than ECM trees, while the organic N uptake did not differ between mycorrhizal types. We conclude that ECM trees are less efficient in inorganic N uptake than AM trees, but ECM trees increase root C release as an adaptive response to dry soil to maintain hydraulic conductivity and/or nutrient availability. These systematic differences in key biogeochemical processes support hints on the key role of the mycorrhizal types in coupling C and N cycles in temperate forests. © The Author 2017. Published by Oxford

  16. The combined influence of the main European circulation patterns on carbon uptake by ecosystems

    NASA Astrophysics Data System (ADS)

    Bastos, Ana; Gouveia, Célia; Trigo, Ricardo

    2014-05-01

    Understanding how natural climate variability affects carbon uptake by land and ocean pools is particularly relevant to better characterize human impact on the carbon cycle. Recently, we have contributed to assess the major role played by the El-Niño/Southern Oscillation in driving inter-annual variability (IAV) of carbon uptake by land ecosystems and significantly influencing global CO2 air-borne fraction [1]. Despite the prominent role played by ENSO, other important teleconnections on the hemispheric scale have deserved less attention. On the European scale, the main mode of variability is the North-Atlantic Oscillation (NAO), which controls storm tracks position and drives changes in temperature and precipitation over the whole region, affecting vegetation dynamics [2]. Besides NAO, a few additional large scale circulation patterns the Scandinavian (SC) and East-Atlantic (EA) Patterns, are also known to influence significantly the European climate [3]. Different combinations of these teleconnection polarities have been recently shown to modulate the overall role of the NAO impact location and strength, thus affecting winter temperature and precipitation patterns over Europe [4]. This work aims to answer the following questions: (i) how do NAO, EA and SC affect vegetation carbon uptake IAV? (ii) do the interactions between these three modes have a significant impact on land CO2 IAV? (iii) what is the contribution of the different physical variables to ecosystems' response to these modes? (iv) how well do the state-of-the-art Earth System Models (ESMs) from CMIP5 represent these climate variability modes and the corresponding carbon fluxes? We first analyze observational data to assess the relationships between the different combinations of NAO, SC and EA polarities and IAV of gross and net primary production (GPP and NPP, respectively), as well as the most relevant driving factors of ecosystem's response to those variability patterns. Although the winter state

  17. Carbon isotopes of dissolved inorganic carbon reflect utilization of different carbon sources by microbial communities in two limestone aquifer assemblages

    NASA Astrophysics Data System (ADS)

    Nowak, Martin E.; Schwab, Valérie F.; Lazar, Cassandre S.; Behrendt, Thomas; Kohlhepp, Bernd; Totsche, Kai Uwe; Küsel, Kirsten; Trumbore, Susan E.

    2017-08-01

    Isotopes of dissolved inorganic carbon (DIC) are used to indicate both transit times and biogeochemical evolution of groundwaters. These signals can be complicated in carbonate aquifers, as both abiotic (i.e., carbonate equilibria) and biotic factors influence the δ13C and 14C of DIC. We applied a novel graphical method for tracking changes in the δ13C and 14C of DIC in two distinct aquifer complexes identified in the Hainich Critical Zone Exploratory (CZE), a platform to study how water transport links surface and shallow groundwaters in limestone and marlstone rocks in central Germany. For more quantitative estimates of contributions of different biotic and abiotic carbon sources to the DIC pool, we used the NETPATH geochemical modeling program, which accounts for changes in dissolved ions in addition to C isotopes. Although water residence times in the Hainich CZE aquifers based on hydrogeology are relatively short (years or less), DIC isotopes in the shallow, mostly anoxic, aquifer assemblage (HTU) were depleted in 14C compared to a deeper, oxic, aquifer complex (HTL). Carbon isotopes and chemical changes in the deeper HTL wells could be explained by interaction of recharge waters equilibrated with post-bomb 14C sources with carbonates. However, oxygen depletion and δ13C and 14C values of DIC below those expected from the processes of carbonate equilibrium alone indicate considerably different biogeochemical evolution of waters in the upper aquifer assemblage (HTU wells). Changes in 14C and 13C in the upper aquifer complexes result from a number of biotic and abiotic processes, including oxidation of 14C-depleted OM derived from recycled microbial carbon and sedimentary organic matter as well as water-rock interactions. The microbial pathways inferred from DIC isotope shifts and changes in water chemistry in the HTU wells were supported by comparison with in situ microbial community structure based on 16S rRNA analyses. Our findings demonstrate the large

  18. Microbial Group Specific Uptake Kinetics of Inorganic Phosphate and Adenosine-5′-Triphosphate (ATP) in the North Pacific Subtropical Gyre

    PubMed Central

    Björkman, Karin; Duhamel, Solange; Karl, David M.

    2012-01-01

    We investigated the concentration dependent uptake of inorganic phosphate (Pi) and adenosine-5′-triphosphate (ATP) in microbial populations in the North Pacific Subtropical Gyre (NPSG). We used radiotracers to measure substrate uptake into whole water communities, differentiated microbial size classes, and two flow sorted groups; Prochlorococcus (PRO) and non-pigmented bacteria (NPB). The Pi concentrations, uptake rates, and Pi pool turnover times (Tt) were (mean, ±SD); 54.9 ± 35.0 nmol L−1 (n = 22), 4.8 ± 1.9 nmol L−1 day−1 (n = 19), and 14.7 ± 10.2 days (n = 19), respectively. Pi uptake into >2 μm cells was on average 12 ± 7% (n = 15) of the total uptake. The kinetic response to Pi (10–500 nmol L−1) was small, indicating that the microorganisms were close to their maximum uptake velocity (Vmax). Vmax averaged 8.0 ± 3.6 nmol L−1 day−1 (n = 19) in the >0.2 μm group, with half saturation constants (Km) of 40 ± 28 nmol L−1 (n = 19). PRO had three times the cell specific Pi uptake rate of NPB, at ambient concentrations, but when adjusted to cells L−1 the rates were similar, and these two groups were equally competitive for Pi. The Tt of γ-P-ATP in the >0.2 μm group were shorter than for the Pi pool (4.4 ± 1.0 days; n = 6), but this difference diminished in the larger size classes. The kinetic response to ATP was large in the >0.2 μm class with Vmax exceeding the rates at ambient concentrations (mean 62 ± 27 times; n = 6) with a mean Vmax for γ-P-ATP of 2.8 ± 1.0 nmol L−1 day−1, and Km at 11.5 ± 5.4 nmol L−1 (n = 6). The NPB contribution to γ-P-ATP uptake was high (95 ± 3%, n = 4) at ambient concentrations but decreased to ∼50% at the highest ATP amendment. PRO had Km values 5–10 times greater than NPB. The above indicates that PRO and NPB were in close competition in terms of Pi acquisition

  19. Trade-offs between global warming and day length on the start of the carbon uptake period in seasonally cold ecosystems

    NASA Astrophysics Data System (ADS)

    Wohlfahrt, Georg; Cremonese, Edoardo; Hammerle, Albin; Hörtnagl, Lukas; Galvagno, Marta; Gianelle, Damiano; Marcolla, Barbara; Cella, Umberto Morra

    2013-12-01

    is well established that warming leads to longer growing seasons in seasonally cold ecosystems. Whether this goes along with an increase in the net ecosystem carbon dioxide (CO2) uptake is much more controversial. We studied the effects of warming on the start of the carbon uptake period (CUP) of three mountain grasslands situated along an elevational gradient in the Alps. To this end, we used a simple empirical model of the net ecosystem CO2 exchange, calibrated, and forced with multiyear empirical data from each site. We show that reductions in the quantity and duration of daylight associated with earlier snowmelts were responsible for diminishing returns, in terms of carbon gain, from longer growing seasons caused by reductions in daytime photosynthetic uptake and increases in nighttime losses of CO2. This effect was less pronounced at high, compared to low, elevations, where the start of the CUP occurred closer to the summer solstice when changes in day length and incident radiation are minimal.

  20. Net uptake of atmospheric CO2 by coastal submerged aquatic vegetation

    PubMed Central

    Tokoro, Tatsuki; Hosokawa, Shinya; Miyoshi, Eiichi; Tada, Kazufumi; Watanabe, Kenta; Montani, Shigeru; Kayanne, Hajime; Kuwae, Tomohiro

    2014-01-01

    ‘Blue Carbon’, which is carbon captured by marine living organisms, has recently been highlighted as a new option for climate change mitigation initiatives. In particular, coastal ecosystems have been recognized as significant carbon stocks because of their high burial rates and long-term sequestration of carbon. However, the direct contribution of Blue Carbon to the uptake of atmospheric CO2 through air-sea gas exchange remains unclear. We performed in situ measurements of carbon flows, including air-sea CO2 fluxes, dissolved inorganic carbon changes, net ecosystem production, and carbon burial rates in the boreal (Furen), temperate (Kurihama), and subtropical (Fukido) seagrass meadows of Japan from 2010 to 2013. In particular, the air-sea CO2 flux was measured using three methods: the bulk formula method, the floating chamber method, and the eddy covariance method. Our empirical results show that submerged autotrophic vegetation in shallow coastal waters can be functionally a sink for atmospheric CO2. This finding is contrary to the conventional perception that most near-shore ecosystems are sources of atmospheric CO2. The key factor determining whether or not coastal ecosystems directly decrease the concentration of atmospheric CO2 may be net ecosystem production. This study thus identifies a new ecosystem function of coastal vegetated systems; they are direct sinks of atmospheric CO2. PMID:24623530

  1. Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Mol, Jacoba; Thomas, Helmuth; Myers, Paul G.; Hu, Xianmin; Mucci, Alfonso

    2018-02-01

    The Mackenzie Shelf in the southeastern Beaufort Sea is a region that has experienced large changes in the past several decades as warming, sea-ice loss, and increased river discharge have altered carbon cycling. Upwelling and downwelling events are common on the shelf, caused by strong, fluctuating along-shore winds, resulting in cross-shelf Ekman transport, and an alternating estuarine and anti-estuarine circulation. Downwelling carries dissolved inorganic carbon (DIC) and other remineralization products off the shelf and into the deep basin for possible long-term storage in the world's oceans. Upwelling carries DIC and nutrient-rich waters from the Pacific-origin upper halocline layer (UHL) onto the shelf. Profiles of DIC and total alkalinity (TA) taken in August and September of 2014 are used to investigate the cycling of carbon on the Mackenzie Shelf. The along-shore transport of water and the cross-shelf transport of DIC are quantified using velocity field output from a simulation of the Arctic and Northern Hemisphere Atlantic (ANHA4) configuration of the Nucleus of European Modelling of the Ocean (NEMO) framework. A strong upwelling event prior to sampling on the Mackenzie Shelf took place, bringing CO2-rich (elevated pCO2) water from the UHL onto the shelf bottom. The maximum on-shelf DIC flux was estimated at 16.9×103 mol C d-1 m-2 during the event. The maximum on-shelf transport of DIC through the upwelling event was found to be 65±15×10-3 Tg C d-1. TA and the oxygen isotope ratio of water (δ18O-H2O) are used to examine water-mass distributions in the study area and to investigate the influence of Pacific Water, Mackenzie River freshwater, and sea-ice melt on carbon dynamics and air-sea fluxes of carbon dioxide (CO2) in the surface mixed layer. Understanding carbon transfer in this seasonally dynamic environment is key to quantify the importance of Arctic shelf regions to the global carbon cycle and provide a basis for understanding how it will

  2. Effect of long-term drought on carbon allocation and nitrogen uptake of Pinus sylvestris seedlings

    NASA Astrophysics Data System (ADS)

    Pumpanen, Jukka; Aaltonen, Heidi; Lindén, Aki; Köster, Kajar; Biasi, Christina; Heinonsalo, Jussi

    2015-04-01

    Weather extremes such as drought events are expected to increase in the future as a result of climate change. The drought affects the allocation of carbon assimilated by plants e.g. by modifying the root to shoot ratio, amount of fine roots and the amount of mycorrhizal fungal hyphae. We studied the effect of long term drought on the allocation of carbon in a common garden experiment with 4-year-old Pinus sylvestris seedlings. Half of the seedlings were exposed to long-term drought by setting the soil water content close to wilting point for over two growing seasons whereas the other half was grown in soil close to field capacity. We conducted a pulse labelling with 13CO2 in the end of the study by injecting a known amount of 13C enriched CO2 to the seedlings and measuring the CO2 uptake and distribution of 13C to the biomass of the seedlings and to the root and rhizosphere respiration. In addition, we studied the effect of drought on the decomposition of needle litter and uptake of nitrogen by 15N labelled needles buried in the soil in litter bags. The litterbags were collected and harvested in the end of the experiment and the changes in microbial community in the litterbags were studied from the phospholipid fatty acid (PLFA) composition. We also determined the 15N isotope concentrations from the needles of the seedlings to study the effect of drought on the nitrogen uptake of the seedlings. Our results indicate that the drought had a significant effect both on the biomass allocation of the seedlings and on the microbial species composition. The amount of carbon allocated belowground was much higher in the seedlings exposed to drought compared to the control seedlings. The seedlings seemed to adapt their carbon allocation to long-term drought to sustain adequate needle biomass and water uptake. The seedlings also adapted their osmotic potential and photosynthesis capacity to sustain the long-term drought as was indicated by the measurements of osmotic potential

  3. Inter-annual Variability in Global Suspended Particulate Inorganic Carbon Inventory Using Space-based Measurements

    NASA Astrophysics Data System (ADS)

    Hopkins, J.; Balch, W. M.; Henson, S.; Poulton, A. J.; Drapeau, D.; Bowler, B.; Lubelczyk, L.

    2016-02-01

    Coccolithophores, the single celled phytoplankton that produce an outer covering of calcium carbonate coccoliths, are considered to be the greatest contributors to the global oceanic particulate inorganic carbon (PIC) pool. The reflective coccoliths scatter light back out from the ocean surface, enabling PIC concentration to be quantitatively estimated from ocean color satellites. Here we use datasets of AQUA MODIS PIC concentration from 2003-2014 (using the recently-revised PIC algorithm), as well as statistics on coccolithophore vertical distribution derived from cruises throughout the world ocean, to estimate the average global (surface and integrated) PIC standing stock and its associated inter-annual variability. In addition, we divide the global ocean into Longhurst biogeochemical provinces, update the PIC biomass statistics and identify those regions that have the greatest inter-annual variability and thus may exert the greatest influence on global PIC standing stock and the alkalinity pump.

  4. Radiocarbon and stable-isotope geochemistry of organic and inorganic carbon in Lake Superior

    NASA Astrophysics Data System (ADS)

    Zigah, Prosper K.; Minor, Elizabeth C.; Werne, Josef P.

    2012-03-01

    We present a lake-wide investigation of Lake Superior carbon and organic matter biogeochemistry using radiocarbon, stable isotope, and carbon concentrations. Dissolved inorganic carbon (DIC) abundance in the lake was 121-122 Tg C, with offshore concentration andδ13C values being laterally homogenous and tightly coupled to the physical and thermal regime and biochemical processes. Offshore Δ14C of DIC (50-65‰) exhibited lateral homogeneity and was more 14C enriched than co-occurring atmospheric CO2 (˜38‰); nearshore Δ14C of DIC (36-38‰) was similar to atmospheric CO2. Dissolved organic carbon (DOC) abundance was 14.2-16.4 Tg C. DOC's concentration and δ13C were homogenous in June (mixed lake), but varied laterally during August (stratification) possibly due to spatial differences in lake productivity. Throughout sampling, DOC had modern radiocarbon values (14-58‰) indicating a semilabile nature with a turnover time of ≤60 years. Lake particulate organic carbon (POC, 0.9-1.3 Tg C) was consistently 13C depleted relative to DOC. The δ15N of epilimnetic particulate organic nitrogen shifted to more negative values during stratification possibly indicating greater use of nitrate (rather than ammonium) by phytoplankton in August. POC's radiocarbon was spatially heterogeneous (Δ14C range: 58‰ to -303‰), and generally 14C depleted relative to DOC and DIC. POC 14C depletion could not be accounted for by black carbon in the lake but, because of its spatial and temporal distribution, is attributed to sediment resuspension. The presence of old POC within the epilimnion of the open lake indicates possible benthic-pelagic coupling in the lake's organic carbon cycle; the ultimate fate of this old POC bears further investigation.

  5. Improving representation of nitrogen uptake, allocation, and carbon assimilation in the Community Land Model

    NASA Astrophysics Data System (ADS)

    Ghimire, B.; Riley, W. J.; Koven, C.

    2013-12-01

    Nitrogen is the most important nutrient limiting plant carbon assimilation and growth, and is required for production of photosynthetic enzymes, growth and maintenance respiration, and maintaining cell structure. The forecasted rise in plant available nitrogen through atmospheric nitrogen deposition and the release of locked soil nitrogen by permafrost thaw in high latitude ecosystems is likely to result in an increase in plant productivity. However a mechanistic representation of plant nitrogen dynamics is lacking in earth system models. Most earth system models ignore the dynamic nature of plant nutrient uptake and allocation, and further lack tight coupling of below- and above-ground processes. In these models, the increase in nitrogen uptake does not translate to a corresponding increase in photosynthesis parameters, such as maximum Rubisco capacity and electron transfer rate. We present an improved modeling framework implemented in the Community Land Model version 4.5 (CLM4.5) for dynamic plant nutrient uptake, and allocation to different plant parts, including leaf enzymes. This modeling framework relies on imposing a more realistic flexible carbon to nitrogen stoichiometric ratio for different plant parts. The model mechanistically responds to plant nitrogen uptake and leaf allocation though changes in photosynthesis parameters. We produce global simulations, and examine the impacts of the improved nitrogen cycling. The improved model is evaluated against multiple observations including TRY database of global plant traits, nitrogen fertilization observations and 15N tracer studies. Global simulations with this new version of CLM4.5 showed better agreement with the observations than the default CLM4.5-CN model, and captured the underlying mechanisms associated with plant nitrogen cycle.

  6. Electron Microscopy of Tungsten Disulphide Inorganic Nanomaterials

    DTIC Science & Technology

    2009-09-01

    cylindrical molecule similar to a carbon nanotube. Inorganic nanotubes have been observed in some mineral deposits. Linus Pauling suggested the...diffraction pattern was due to the carbon coating. Figure 6 SAED taken from the single nanotube shown in figure 5 REFERENCES 1. Pauling , L; "The

  7. The Uptake of Heat and Carbon by the Southern Ocean in the CMIP5 Earth System Models

    NASA Astrophysics Data System (ADS)

    Russell, J. L.; Stouffer, R. J.; Dunne, J. P.; John, J. G.

    2011-12-01

    The Southern Ocean surrounding the Antarctic continent accounts for a disproportionate share of the heat and carbon dioxide that is removed from contact with the atmosphere into the ocean. The vigorous air-sea exchange driven by the Southern Hemisphere Westerlies, combined with the dearth of observations, makes the Southern Ocean a major source of uncertainty in projecting the rate of warming of our atmosphere, especially considering that the vertical mixing of the ocean and the corollary air-sea fluxes may be vulnerable to climate change. We assess the heat and carbon uptake by the Southern Ocean in future simulations by the IPCC-AR5 Earth System Models (ESMs), focusing on the GFDL simulations. Using the 1860 control simulation as our baseline, we explore the differences in heat and carbon uptake between the major "Representative Concentration Pathways" (RCPs) as simulated by the various ESMs in order to quantify the uncertainties in the climate projections related to the Southern Ocean window into the deep ocean reservoir.

  8. Wind-driven Ocean Circulation and the Spatial-temporal Variability of Dissolved Inorganic Carbon in the Gulf of Tehuantepec, North Eastern Tropical Pacific

    NASA Astrophysics Data System (ADS)

    Chapa, C.; Beier, E.; Durazo, R.; Martin Hernandez-Ayon, J. M.; Alin, S. R.; Lopez-Perez, A.

    2016-12-01

    The relationship between the surface enrichment of dissolved inorganic carbon (DIC) and wind variability and circulation in the Gulf of Tehuantepec (GT) was examined from satellite images and in situ data from three cruises (June 2010; April and November 2013). Monthly mean wind climatologies (and derived variables), sea surface temperature and sea surface height anomaly fields were analyzed in the GT and part of the NETP. Signal decomposition according to circulation scales (seasonal, inter-annual, mesoscale) was performed using harmonic analysis for the seasonal components, and empirical orthogonal functions for the residuals, applied to satellite sea-level anomaly data. The results show that wind is the main driving force of the variability in the GT. Mesoscale is the variable with the highest percent of local variance (25-75%), due mainly to mesoscale eddies, followed by seasonality (20-55%), and finally the inter-annual signal (10-30%), dominated by ENSO. Mesoscale and seasonality prevailed during the samplings. The changes in circulation led to variations in the concentration of surface DIC ranging between 100 and 300 µmol kg-1 (436 µatm) due to Ekman pumping. The largest enrichment occurred in November 2013 after a strong northerly wind event. However, the predominance of mesoscale events suggests that changes in dissolved inorganic carbon resulting from mesoscale- derived Ekman pumping may become important in the long term and with a larger spatial and temporal coverage. The results suggest that the seasonal cycle of dissolved inorganic carbon may be linked to wind seasonality.

  9. Interaction of carbon nanohorns with plants: Uptake and biological effects

    DOE PAGES

    Lahiani, Mohamed H.; Chen, Jihua; Irin, Fahmida; ...

    2014-10-07

    Single-Walled Carbon Nanohorns (SWCNHs) are a unique carbon-based nanomaterial with promising application in different fields including, medicine, genetic engineering and horticulture. Here, we investigated the biological response of six crop species (barley, corn, rice, soybean, switchgrass, tomato) and tobacco cell culture to the exposure of SWCNHs. We found that SWCNHs can activate seed germination of selected crops and enhance growth of different organs of corn, tomato, rice and soybean. At cellular level, growth of tobacco cells was increased in response to exposure of SWCNHs (78% increase compared to control). Uptake of SWCNHs by exposed crops and tobacco cells was confirmedmore » by transmission electron microscopy (TEM) and quantified by microwave induced heating (MIH) technique. At genetic level, SWCNHs were able to affect expression of a number of tomato genes that are involved in stress responses, cellular responses and metabolic processes. Our conclusion is that SWCNHs can be used as plant growth regulators and have the potential for plant-related applications.« less

  10. Photoluminescent carbon dots based on a rare 3D inorganic-organic hybrid cadmium borate crystal.

    PubMed

    Zhou, Kang; Zhang, Wen-Jin; Luo, Yuan-Zhang; Pan, Chun-Yang

    2018-05-17

    A 3D inorganic-organic hybridized skeleton cadmium borate [Cden][B5O8(OH)] (1) (en = ethylenediamine) has been solvothermally synthesized. By calcining it, specific shape carbon dots (C-dots) with abundant free radicals were observed. In addition, C-dots in the ethanol phase exhibited variable photoluminescence and showed rare turn on or off effects to Cr3+ ions and CdSe/ZnS quantum dots, but only a turn on effect to Cs+ ions and a turn off effect to CsPbBr3 quantum dots.

  11. Sediment-water fluxes of dissolved inorganic carbon, O2,nutrients, and N2 from the hypoxic region of the Louisianacontinental shelf

    EPA Science Inventory

    Sediment fluxes of dissolved inorganic carbon (DIC), O2, nutrients, and N2 (denitrification) were measured on the Louisiana Continental Shelf during six cruises from 2005 to 2007. On each cruise, three to seven stations were occupied in regions of the shelf that experience summer...

  12. Electrochemical determination of inorganic mercury and arsenic--A review.

    PubMed

    Zaib, Maria; Athar, Muhammad Makshoof; Saeed, Asma; Farooq, Umar

    2015-12-15

    Inorganic mercury and arsenic encompasses a term which includes As(III), As(V) and Hg(II) species. These metal ions have been extensively studied due to their toxicity related issues. Different analytical methods are used to monitor inorganic mercury and arsenic in a variety of samples at trace level. The present study reviews various analytical techniques available for detection of inorganic mercury and arsenic with particular emphasis on electrochemical methods especially stripping voltammetry. A detailed critical evaluation of methods, advantages of electrochemical methods over other analytical methods, and various electrode materials available for mercury and arsenic analysis is presented in this review study. Modified carbon paste electrode provides better determination due to better deposition with linear and improved response under studied set of conditions. Biological materials may be the potent and economical alternative as compared to macro-electrodes and chemically modified carbon paste electrodes in stripping analysis of inorganic mercury and arsenic. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Mycorrhizal Controls on Nitrogen Uptake Drive Carbon Cycling at the Global Scale

    NASA Astrophysics Data System (ADS)

    Shi, M.; Fisher, J. B.; Brzostek, E. R.; Phillips, R.

    2015-12-01

    Nearly all plants form symbiotic relationships with one of two types of mycorrhizal fungi—arbuscular mycorrhizae (AM) and ectomycorrhizal (ECM) fungi, which are essential to global biogeochemical cycling of nutrient elements. In soils with higher rates of nitrogen and phosphorus mineralization from organic matter, AM-associated plants can be better adapted than ECM-associated plants. Importantly, the photosynthate costs of nutrient uptake for AM-associated plants are usually lower than that for ECM-associated plants. Thus, the global carbon cycle is closely coupled with mycorrhizal controls on N uptake. To investigate the potential climate dependence of terrestrial environments from AM- and ECM-associated plants, this study uses the Community Atmosphere Model (CAM) with a plant productivity-optimized N acquisition model—the Fixation and Uptake of Nitrogen (FUN) model—integrated into its land model—the Community Land Model (CLM). This latest version of CLM coupled with FUN allows for the assessment of mycorrhizal controls on global biogeochemical cycling. Here, we show how the historical evolution of AM- and ECM-associations altered regional and global biogeochemical cycling and climate, and future projections over the next century.

  14. Carbon nanotube uptake and toxicity in the brain.

    PubMed

    Zhang, Leying; Alizadeh, Darya; Badie, Behnam

    2010-01-01

    The development of novel drug delivery systems is essential for the improvement of therapeutics for most human diseases. Currently used cellular delivery systems, such as viral vectors, liposomes, cationic lipids, and polymers, may have limited clinical efficacy because of safety issues, low gene transfer efficiency, or cytotoxicity. Carbon nanotubes (CNTs) have garnered much interest as possible biological vectors after the recent discovery of their capacity to penetrate cells. Inspite of the prominence of CNT studies in the nanotechnology literature, exploration of their application to central nervous system (CNS) therapeutics is at a very early stage. Before CNTs are used for treatment of brain and spinal cord disorders, however, several issues such as their CNS penetration and toxicity need to be addressed. Here, we discuss methods by which CNT uptake and toxicity can be assessed in animal models.

  15. Determination of the origin of dissolved inorganic carbon in groundwater around a reclaimed landfill in Otwock using stable carbon isotopes.

    PubMed

    Porowska, Dorota

    2015-05-01

    Chemical and isotopic analyses of groundwater from piezometers located around a reclaimed landfill in Otwock (Poland) were performed in order to trace the origin of dissolved inorganic carbon (DIC) in the groundwater. Due to differences in the isotopic composition of carbon from different sources, an analysis of stable carbon isotopes in the groundwater, together with the Keeling plot approach and a two-component mixing model allow us to evaluate the relative contributions of carbon from these sources in the groundwater. In the natural (background) groundwater, DIC concentrations and the isotopic composition of DIC (δ(13)CDIC) comes from two sources: decomposition of organic matter and carbonate dissolution within the aquifer sediments, whereas in the leachate-contaminated groundwater, DIC concentrations and δ(13)CDIC values depend on the degradation of organic matter within the aquifer sediments and biodegradation of organic matter stored in the landfill. From the mixing model, about 4-54% of the DIC pool is derived from organic matter degradation and 96-46% from carbonate dissolution in natural conditions. In the leachate-contaminated groundwater, about 20-53% of the DIC is derived from organic matter degradation of natural origin and 80-47% from biodegradation of organic matter stored in the landfill. Partial pressure of CO2 (P CO2) was generally above the atmospheric, hence atmospheric CO2 as a source of carbon in DIC pool was negligible in the aquifer. P CO2 values in the aquifer in Otwock were always one to two orders of magnitude above the atmospheric P CO2, and thus CO2 escaped directly into the vadose zone. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Phosphate and ATP uptake by lake bacteria: does taxonomical identity matter?

    PubMed Central

    Sommaruga, Ruben; Teresa Pérez, María

    2016-01-01

    Summary Phosphorus often limits bacterial production in freshwater ecosystems. However, little is known on whether different bacteria contribute to inorganic and organic phosphorus uptake proportionally to their relative abundance and production. Here, we followed the temporal dynamics of the main heterotrophic bacterial taxa taking up inorganic phosphate (33P‐Pi) and organic phosphorus (33P‐ATP) in two mountain lakes and compared them to their contribution to bacterial production (3H‐leucine uptake). The short turnover times for Pi and ATP suggested that in both lakes, phosphorus was limiting most of the year. The bulk uptake rates and the fractions of cells labelled positive for Pi and ATP uptake followed a seasonal trend with minima in winter and maxima in summer. Generally, the bacterial taxa examined contributed to Pi and ATP uptake proportionally to their relative abundance, but not always to their contribution to bacterial production. For instance, AcI Actinobacteria were often underrepresented in phosphorus uptake compared with leucine incorporation suggesting they might have high intracellular C:P ratios. Our results emphasize that ATP utilization is widespread among freshwater bacteria and indicate that members within the dominant bacterial taxa (Actinobacteria and Betaproteobacteria) have variable phosphorus requirements, probably due to their different growth potential and variable degrees of homeostasis. PMID:27130525

  17. Nitrogen uptake and utilization by intact plants

    NASA Technical Reports Server (NTRS)

    Raper, C. D., Jr.; Tolley-Henry, L. C.

    1986-01-01

    The results of experiments support the proposed conceptual model that relates nitrogen uptake activity by plants as a balanced interdependence between the carbon-supplying function of the shoot and the nitrogen-supplying function of the roots. The data are being used to modify a dynamic simulation of plant growth, which presently describes carbon flows through the plant, to describe nitrogen uptake and assimilation within the plant system. Although several models have been proposed to predict nitrogen uptake and partitioning, they emphasize root characteristics affecting nutrient uptake and relay on empirical methods to describe the relationship between nitrogen and carbon flows within the plant. Researchers, on the other hand, propose to continue to attempt a mechanistic solution in which the effects of environment on nitrogen (as well as carbon) assimilation are incorporated through their direct effects on photosynthesis, respiration, and aging processes.

  18. Dynamics of organic and inorganic carbon in surface sediments of the Yellow River Estuary

    NASA Astrophysics Data System (ADS)

    Yu, Z.; Wang, X.; Liu, X.; Zhang, E.; Hang, F.

    2017-12-01

    Estuarine sediment is an important carbon reservoir thus may play an important role in the global carbon cycle. However, little is known on the dynamics of organic carbon (OC) and inorganic carbon (IC) in the surface sediment of the Yellow River Estuary, a large estuary in northern China. In this study, we applied element analyses and isotopic approach to study spatial distribution and sources of OC and IC in the Yellow River Estuary. We found that TIC concentration (6.3-20.1 g kg-1) was much higher than TOC (0.2-4.4 g kg-1) in the surface sediment. There showed a large spatial variability in TOC and TIC and their stable isotopes. Both TOC and TIC were higher to the north (2.6 and 14.5 g kg-1) than to the south (1.6 and 12.2 g kg-1), except in the southern bay where TOC and TIC reached 2.7 and 15.4 g kg-1, respectively. Generally, TOC and TIC in our study area was mainly autochthonous. The lower TOC values in the south section were due to relatively higher kinetic energy level whereas the higher values in the bay was attributable to terrigenous matters accumulation and lower kinetic energy level. However, the southern bay revealed the most negative δ13Corg and δ13Ccarb, suggesting that there might exist some transfer of OC to IC in the section. Our study points out that the dynamics of sedimentary carbon in the Yellow River Estuary is influenced by multiple and complex processes, and highlights the importance of carbonate in carbon sequstration.

  19. Predicting Phenologic Response to Water Stress and Implications for Carbon Uptake across the Southeast U.S.

    NASA Astrophysics Data System (ADS)

    Lowman, L.; Barros, A. P.

    2016-12-01

    Representation of plant photosynthesis in modeling studies requires phenologic indicators to scale carbon assimilation by plants. These indicators are typically the fraction of photosynthetically active radiation (FPAR) and leaf area index (LAI) which represent plant responses to light and water availability, as well as temperature constraints. In this study, a prognostic phenology model based on the growing season index is adapted to determine the phenologic indicators of LAI and FPAR at the sub-daily scale based on meteorological and soil conditions. Specifically, we directly model vegetation green-up and die-off responses to temperature, vapor pressure deficit, soil water potential, and incoming solar radiation. The indices are based on the properties of individual plant functional types, driven by observational data and prior modeling applications. First, we describe and test the sensitivity of the carbon uptake response to predicted phenology for different vegetation types. Second, the prognostic phenology model is incorporated into a land-surface hydrology model, the Duke Coupled Hydrology Model with Prognostic Vegetation (DCHM-PV), to demonstrate the impact of dynamic phenology on modeled carbon assimilation rates and hydrologic feedbacks. Preliminary results show reduced carbon uptake rates when incorporating a prognostic phenology model that match well against the eddy-covariance flux tower observations. Additionally, grassland vegetation shows the most variability in LAI and FPAR tied to meteorological and soil conditions. These results highlight the need to incorporate vegetation-specific responses to water limitation in order to accurately estimate the terrestrial carbon storage component of the global carbon budget.

  20. Recycled-tire pyrolytic carbon made functional: A high-arsenite [As(III)] uptake material PyrC350®.

    PubMed

    Mouzourakis, E; Georgiou, Y; Louloudi, M; Konstantinou, I; Deligiannakis, Y

    2017-03-15

    A novel material, PyrC 350 ® , has been developed from pyrolytic-tire char (PyrC), as an efficient low-cost Arsenite [As(III)] adsorbent from water. PyrC 350 ® achieves 31mgg -1 As(III) uptake, that remains unaltered at pH=4-8.5. A theoretical Surface Complexation Model has been developed that explains the adsorption mechanism, showing that in situ formed Fe 3 C, ZnS particles act cooperatively with the carbon matrix for As(III) adsorption. Addressing the key-issue of cost-effectiveness, we provide a comparison of As(III)-uptake effectiveness in conjunction with a cost analysis, showing that PyrC 350 ® stands in the top of [effectiveness/cost] vs. existing carbon-based, low-cost materials. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Heme iron uptake by Caco-2 cells is a saturable, temperature sensitive and modulated by extracellular pH and potassium.

    PubMed

    Arredondo, Miguel; Kloosterman, Janneke; Núñez, Sergio; Segovia, Fabián; Candia, Valeria; Flores, Sebastián; Le Blanc, Solange; Olivares, Manuel; Pizarro, Fernando

    2008-11-01

    It is known that heme iron and inorganic iron are absorbed differently. Heme iron is found in the diet mainly in the form of hemoglobin and myoglobin. The mechanism of iron absorption remains uncertain. This study focused on the heme iron uptake by Caco-2 cells from a hemoglobin digest and its response to different iron concentrations. We studied the intracellular Fe concentration and the effect of time, K+ depletion, and cytosol acidification on apical uptake and transepithelial transport in cells incubated with different heme Fe concentrations. Cells incubated with hemoglobin-digest showed a lower intracellular Fe concentration than cells grown with inorganic Fe. However, uptake and transepithelial transport of Fe was higher in cells incubated with heme Fe. Heme Fe uptake had a low Vmax and Km as compared to inorganic Fe uptake and did not compete with non-heme Fe uptake. Heme Fe uptake was inhibited in cells exposed to K+ depletion or cytosol acidification. Heme oxygenase 1 expression increased and DMT1 expression decreased with higher heme Fe concentrations in the media. The uptake of heme iron is a saturable and temperature-dependent process and, therefore, could occur through a mechanism involving both a receptor and the endocytic pathway.

  2. Uptake and storage of anthropogenic CO2 in the pacific ocean estimated using two modeling approaches

    NASA Astrophysics Data System (ADS)

    Li, Yangchun; Xu, Yongfu

    2012-07-01

    A basin-wide ocean general circulation model (OGCM) of the Pacific Ocean is employed to estimate the uptake and storage of anthropogenic CO2 using two different simulation approaches. The simulation (named BIO) makes use of a carbon model with biological processes and full thermodynamic equations to calculate surface water partial pressure of CO2, whereas the other simulation (named PTB) makes use of a perturbation approach to calculate surface water partial pressure of anthropogenic CO2. The results from the two simulations agree well with the estimates based on observation data in most important aspects of the vertical distribution as well as the total inventory of anthropogenic carbon. The storage of anthropogenic carbon from BIO is closer to the observation-based estimate than that from PTB. The Revelle factor in 1994 obtained in BIO is generally larger than that obtained in PTB in the whole Pacific, except for the subtropical South Pacific. This, to large extent, leads to the difference in the surface anthropogenic CO2 concentration between the two runs. The relative difference in the annual uptake between the two runs is almost constant during the integration processes after 1850. This is probably not caused by dissolved inorganic carbon (DIC), but rather by a factor independent of time. In both runs, the rate of change in anthropogenic CO2 fluxes with time is consistent with the rate of change in the growth rate of atmospheric partial pressure of CO2.

  3. Using satellite-derived optical thickness to assess the influence of clouds on terrestrial carbon uptake

    Treesearch

    S.J. Cheng; A.L. Steiner; D.Y. Hollinger; G. Bohrer; K.J. Nadelhoffer

    2016-01-01

    Clouds scatter direct solar radiation, generating diffuse radiation and altering the ratio of direct to diffuse light. If diffuse light increases plant canopy CO2 uptake, clouds may indirectly influence climate by altering the terrestrial carbon cycle. However, past research primarily uses proxies or qualitative categories of clouds to connect...

  4. Temperature responses of carbon monoxide and hydrogen uptake by vegetated and unvegetated volcanic cinders.

    PubMed

    King, Caitlin E; King, Gary M

    2012-08-01

    Ecosystem succession on a large deposit of volcanic cinders emplaced on Kilauea Volcano in 1959 has resulted in a mosaic of closed-canopy forested patches and contiguous unvegetated patches. Unvegetated and unshaded surface cinders (Bare) experience substantial diurnal temperature oscillations ranging from moderate (16 °C) to extreme (55 °C) conditions. The surface material of adjacent vegetated patches (Canopy) experiences much smaller fluctuations (14-25 °C) due to shading. To determine whether surface material from these sites showed adaptations by carbon monoxide (CO) and hydrogen (H(2)) consumption to changes in ambient temperature regimes accompanying succession, we measured responses of CO and H(2) uptake to short-term variations in temperature and long-term incubations at elevated temperature. Based on its broader temperature optimum and lower activation energy, Canopy H(2) uptake was less sensitive than Bare H(2) uptake to temperature changes. In contrast, Bare and Canopy CO uptake responded similarly to temperature during short-term incubations, indicating no differences in temperature sensitivity. However, during extended incubations at 55 °C, CO uptake increased for Canopy but not Bare material, which indicated that the former was capable of thermal adaptation. H(2) uptake for material from both sites was completely inhibited at 55 °C throughout extended incubations. These results indicated that plant development during succession did not elicit differences in short-term temperature responses for Bare and Canopy CO uptake, in spite of previously reported differences in CO oxidizer community composition, and differences in average daily and extreme temperatures. Differences associated with vegetation due to succession did, however, lead to a notable capacity for thermophilic CO uptake by Canopy but not Bare material.

  5. Temperature responses of carbon monoxide and hydrogen uptake by vegetated and unvegetated volcanic cinders

    PubMed Central

    King, Caitlin E; King, Gary M

    2012-01-01

    Ecosystem succession on a large deposit of volcanic cinders emplaced on Kilauea Volcano in 1959 has resulted in a mosaic of closed-canopy forested patches and contiguous unvegetated patches. Unvegetated and unshaded surface cinders (Bare) experience substantial diurnal temperature oscillations ranging from moderate (16 °C) to extreme (55 °C) conditions. The surface material of adjacent vegetated patches (Canopy) experiences much smaller fluctuations (14–25 °C) due to shading. To determine whether surface material from these sites showed adaptations by carbon monoxide (CO) and hydrogen (H2) consumption to changes in ambient temperature regimes accompanying succession, we measured responses of CO and H2 uptake to short-term variations in temperature and long-term incubations at elevated temperature. Based on its broader temperature optimum and lower activation energy, Canopy H2 uptake was less sensitive than Bare H2 uptake to temperature changes. In contrast, Bare and Canopy CO uptake responded similarly to temperature during short-term incubations, indicating no differences in temperature sensitivity. However, during extended incubations at 55 °C, CO uptake increased for Canopy but not Bare material, which indicated that the former was capable of thermal adaptation. H2 uptake for material from both sites was completely inhibited at 55 °C throughout extended incubations. These results indicated that plant development during succession did not elicit differences in short-term temperature responses for Bare and Canopy CO uptake, in spite of previously reported differences in CO oxidizer community composition, and differences in average daily and extreme temperatures. Differences associated with vegetation due to succession did, however, lead to a notable capacity for thermophilic CO uptake by Canopy but not Bare material. PMID:22258097

  6. Bioaccumulation of organic and inorganic selenium in a laboratory food chain

    USGS Publications Warehouse

    Besser, John M.; Canfield, Timothy J.; La Point, Thomas W.

    1993-01-01

    Aquatic organisms accumulated selenium (Se) from inorganic and organic Se species via aqueous and food-chain exposure routes. We measured aqueous and food-chain Se bioaccumulation from selenate, selenite, and seleno-L-methionine in a laboratory food chain of algae (Chlamydomonas reinhardtii), daphnids (Daphnia magna), and fish (bluegill, Lepomis macrochirus). Selenium concentrations were monitored radiometrically with 75Se-labeled compounds. All three organisms concentrated Se more strongly from aqueous selenomethionine than from either inorganic Se species. Bioconcentration factors (BCFs) estimated from 1 μg Se/L Se-methionine exposures were approximately 16,000 for algae, 200,000 for daphnids, and 5,000 for bluegills. Algae and daphnids concentrated Se more strongly from selenite (BCFs = 220–3,600) than selenate (BCFs = 65–500) whereas bluegills concenrated Se about equally from both inorganic species (estimated BCFs = 13 to 106). Bioaccumulation of foodborne Se by daphnids and bluegills was similar in food chains dosed with different Se species. Daphnids and bluegills did not accumulate Se concentrations greater than those in their diet, except at very low dietary Se concentrations. Food-chain concentration factors (CFs) for daphnids decreased from near 1.0 to 0.5 with increases in algal Se concentrations, whereas CFs estimated from bluegill exposures averaged 0.5 over a range of foodborne Se concentrations. In exposures based on selenite, bluegills accumulated greater Se concentrations from food than from water. Aqueous and food-chain Se uptakes were approximately additive, and depuration rates were similar in aqueous, food-chain, and combined exposures. Our results suggest that bluegills in Secontaminated habitats accumulate inorganic Se species primarily via food-chain uptake, although organoselenium compounds such as Se-methionine may contribute significantly to Se bioaccumulation by bluegills via both aqueous and food-chain uptake.

  7. Early snowmelt significantly enhances boreal springtime carbon uptake

    PubMed Central

    Pulliainen, Jouni; Aurela, Mika; Laurila, Tuomas; Aalto, Tuula; Takala, Matias; Salminen, Miia; Kulmala, Markku; Barr, Alan; Heimann, Martin; Lindroth, Anders; Laaksonen, Ari; Derksen, Chris; Mäkelä, Annikki; Markkanen, Tiina; Lemmetyinen, Juha; Susiluoto, Jouni; Dengel, Sigrid; Mammarella, Ivan; Tuovinen, Juha-Pekka; Vesala, Timo

    2017-01-01

    We determine the annual timing of spring recovery from space-borne microwave radiometer observations across northern hemisphere boreal evergreen forests for 1979–2014. We find a trend of advanced spring recovery of carbon uptake for this period, with a total average shift of 8.1 d (2.3 d/decade). We use this trend to estimate the corresponding changes in gross primary production (GPP) by applying in situ carbon flux observations. Micrometeorological CO2 measurements at four sites in northern Europe and North America indicate that such an advance in spring recovery would have increased the January–June GPP sum by 29 g⋅C⋅m−2 [8.4 g⋅C⋅m−2 (3.7%)/decade]. We find this sensitivity of the measured springtime GPP to the spring recovery to be in accordance with the corresponding sensitivity derived from simulations with a land ecosystem model coupled to a global circulation model. The model-predicted increase in springtime cumulative GPP was 0.035 Pg/decade [15.5 g⋅C⋅m−2 (6.8%)/decade] for Eurasian forests and 0.017 Pg/decade for forests in North America [9.8 g⋅C⋅m−2 (4.4%)/decade]. This change in the springtime sum of GPP related to the timing of spring snowmelt is quantified here for boreal evergreen forests. PMID:28973918

  8. Age alters uptake pattern of organic and inorganic nitrogen by rubber trees.

    PubMed

    Liu, Min; Xu, Fanzhen; Xu, Xingliang; Wanek, Wolfgang; Yang, Xiaodong

    2018-04-05

    Several studies have explored plant nutrient acquisition during ecosystem succession, but it remains unclear how age affects nitrogen (N) acquisition by the same tree species. Clarifying the age effect will be beneficial to fertilization management through improving N-use efficiency and reducing the risk of environmental pollution due to NO3- leaching. To clarify the effect of age on N uptake, rubber (Hevea brasiliensis (Willd. ex A. Juss.) Muell. Arg.) plantations of five ages (7, 16, 24, 32 and 49 years) were selected in Xishuangbanna of southern China for brief 15N exposures of intact roots using field hydroponic experiments. 15N-labeled NH4+, NO3- or glycine were applied in this study. All targeted rubber trees uptake rates followed an order of NH4+ > glycine > NO3-. As age increased, NH4+ uptake increased first and then decreased sharply, partly consistent with the pattern of soil NH4+ concentrations. Uptake of glycine decreased first and then increased gradually, while no significant change of NO3- uptake rates existed with increasing age. Overall, rubber trees with ages from 7 to 49 years all showed a preference for NH4+ uptake. Young rubber trees (7 and 16 years) had higher NH4+ and lower glycine preferences than older trees (24, 32 and 49 years). Mycorrhizal colonization rates of rubber trees were higher in intermediately aged plantations (16, 24 and 32 years) than in plantations aged 7 and 49 years. A positive relationship was observed between arbuscular mycorrhizal colonization rates and NO3- preference. The results from this study demonstrate that rubber trees do not change their preference for NH4+ but strongly decreased their reliance on it with age. These findings indicate that the shift of N uptake patterns with age should be taken into account for rubber fertilization management to improve N-use efficiency and reduce the risk of environmental pollution during rubber production.

  9. O3 uptake and drought stress effects on carbon acquisition of ponderosa pine in natural stands

    Treesearch

    N.E. Grulke; H.K. Preisler; C. Rose; J. Kirsch; L. Balduman

    2002-01-01

    • The effect of O3 exposure or uptake on carbon acquisition (net assimilation (A) or gross photosynthesis (Pg)), with and without drought stress, is reported here in 40-yr-old-ponderosa pine (Pinus ponderosa) trees. • Maximum daily gas exchange was...

  10. [Effect of inorganic amendments on the stabilization of heavy metals in contaminated soils].

    PubMed

    Cao, Meng-hua; Zhu, Xi; Liu, Huang-cheng; Wang, Lin-ling; Chen, Jing

    2013-09-01

    Effects of single and mixed inorganic amendments on the stabilization of heavy metals in contaminated soils were investigated. Significant synergistic effects on the stabilization of Zn and Cu were observed with the mixed inorganic amendments of KH2PO4 and Ca(OH)2 in the laboratory test. In the field test, the stabilization ratios of Zn, Cu and Cd were 41.8%, 28.2% and 48.4%, respectively, with the dosage of 0.5 kg x m(-2). The growth of peanut was inhibited by the addition of the inorganic amendments. Meanwhile, the uptake of heavy metals was reduced in peanut.

  11. Simultaneous uptake of NOM and Microcystin-LR by anion exchange resins: Effect of inorganic ions and resin regeneration.

    PubMed

    Dixit, Fuhar; Barbeau, Benoit; Mohseni, Madjid

    2018-02-01

    This study investigated the efficiency of a strongly basic macroporous anion exchange resin for the co-removal of Microcystin-LR (MCLR) and natural organic matter (NOM) in waters affected by toxic algal blooms. Environmental factors influencing the uptake behavior included MCLR and resin concentrations, NOM and anionic species, specifically nitrate, sulphate and bicarbonate. A860 resin exhibited an excellent adsorption capacity of 3800 μg/g; more than 60% of the MCLR removal was achieved within 10 min with a resin dosage of 200 mg/L (∼1 mL/L). Further, kinetic studies revealed that the overall removal of MCLR is influenced by both external diffusion and intra-particle diffusion. Increasing NOM concentration resulted in a significant reduction of MCLR uptake, especially at lower resin dosages, where a competitive uptake between the charged NOM fractions and MCLR was observed due to limited active sites. In addition, MCLR uptake was significantly reduced in the presence of sulphate and nitrate in the water matrix. Moreover, performance of the resin proved to be stable from one regeneration cycle to another. Approximately 80% of MCLR and 50% of dissolved organic carbon (DOC) were recovered in the regenerated brine. Evidences of resin saturation and site reduction were also observed after 2000 bed volumes (BV) of operation. For all the investigated water matrices, a resin dosage of 1000 mg/L (∼4.5 mL/L) was sufficient to lower MCLR concentration from 100 μg/L to below the World Health Organization guideline of 1 μg/L, while simultaneously providing more than 80% NOM removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Heterogeneous Uptake of HO2 Radicals onto Submicron Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Matthews, P. S.; George, I. J.; Brooks, B.; Whalley, L. K.; Baeza-Romero, M. T.; Heard, D. E.

    2012-12-01

    OH and HO2 (HOx) radicals are closely coupled and OH is responsible for the majority of the oxidation in the troposphere and controls the concentrations of many trace species. Therefore, it is important to be able to accurately predict HOx concentrations. However, some field measurement studies have reported significantly lower HO2 radical concentrations than calculated by constrained box models using detailed chemical mechanisms. Although the inclusion of halogen chemistry into the mechanisms can explain much of the differences in the marine boundary layer (MBL) (1,2), HO2 uptake by aerosols has been suggested as a possible sink in the MBL (2), the Arctic troposphere (3) and the upper troposphere (4). There have been very few laboratory studies (5,6) on HO2 uptake by aerosols and the rates and mechanism is still uncertain. The HO2 uptake coefficients were measured for a variety of atmospherically relevant inorganic and organic aerosols. The measurements were performed using an aerosol flow tube combined with a Fluorescence Assay by Gas Expansion (FAGE) detector. The sensitive FAGE cell allowed low HO2 concentrations (108-109 molecule cm-3) to be injected into the flow tube using a moveable injector. By moving the injector along the flow tube, position dependent HO2 decays were able to be recorded which when plotted against the total aerosol surface area allowed an uptake coefficient to be obtained. The aerosols were generated using an atomiser or by homogeneous nucleation and the total aerosol surface area was measured using a Scanning Mobility Particle Sizer. The HO2 uptake coefficient (γ) was measured at room temperature for dry inorganic salts and dry organics (γ< 0.004), wet inorganic salts and wet organics (γ= 0.002-0.005), wet copper doped ammonium sulfate aerosols (γ= 0.28± 0.05) and ammonium sulfate aerosols doped with different molar amounts of iron (γ= 0.003-0.06). The pH dependence of the HO2 uptake coefficient was investigated, however no

  13. Carbon isotope fractionation of dissolved inorganic carbon (DIC) due to outgassing of carbon dioxide from a headwater stream

    USGS Publications Warehouse

    Doctor, D.H.; Kendall, C.; Sebestyen, S.D.; Shanley, J.B.; Ohte, N.; Boyer, E.W.

    2008-01-01

    The stable isotopic composition of dissolved inorganic carbon (??13C-DIC) was investigated as a potential tracer of streamflow generation processes at the Sleepers River Research Watershed, Vermont, USA. Downstream sampling showed ?? 13C-DIC increased between 3-5??? from the stream source to the outlet weir approximately 0??5 km downstream, concomitant with increasing pH and decreasing PCO2. An increase in ??13C-DIC of 2.4 ?? 0??1??? per log unit decrease of excess PCO2 (stream PCO2 normalized to atmospheric PCO2) was observed from downstream transect data collected during snowmelt. Isotopic fractionation of DIC due to CO2 outgassing rather than exchange with atmospheric CO2 may be the primary cause of increased ?? 13C-DIC values downstream when PCO2 of surface freshwater exceeds twice the atmospheric CO2 concentration. Although CO2 outgassing caused a general increase in stream ??13C-DIC values, points of localized groundwater seepage into the stream were identified by decreases in ??13C-DIC and increases in DIC concentration of the stream water superimposed upon the general downstream trend. In addition, comparison between snowmelt, early spring and summer seasons showed that DIC is flushed from shallow groundwater flowpaths during snowmelt and is replaced by a greater proportion of DIC derived from soil CO2 during the early spring growing season. Thus, in spite of effects from CO2 outgassing, ??13C of DIC can be a useful indicator of groundwater additions to headwater streams and a tracer of carbon dynamics in catchments. Copyright ?? 2007 John Wiley & Sons, Ltd.

  14. Carbonyl sulfide exchange in soils for better estimates of ecosystem carbon uptake

    DOE PAGES

    Whelan, Mary E.; Hilton, Timothy W.; Berry, Joseph A.; ...

    2016-03-21

    Carbonyl sulfide (COS) measurements are one of the emerging tools to better quantify gross primary production (GPP), the largest flux in the global carbon cycle. COS is a gas with a similar structure to CO 2; COS uptake is thought to be a proxy for GPP. However, soils are a potential source or sink of COS. This study presents a framework for understanding soil–COS interactions. Excluding wetlands, most of the few observations of isolated soils that have been made show small uptake of atmospheric COS. Recently, a series of studies at an agricultural site in the central United States foundmore » soil COS production under hot conditions an order of magnitude greater than fluxes at other sites. To investigate the extent of this phenomenon, soils were collected from five new sites and incubated in a variety of soil moisture and temperature states. We found that soils from a desert, an oak savannah, a deciduous forest, and a rainforest exhibited small COS fluxes, behavior resembling previous studies. However, soil from an agricultural site in Illinois, >800 km away from the initial central US study site, demonstrated comparably large soil fluxes under similar conditions. These new data suggest that, for the most part, soil COS interaction is negligible compared to plant uptake of COS. We present a model that anticipates the large agricultural soil fluxes so that they may be taken into account. Furthermore, while COS air-monitoring data are consistent with the dominance of plant uptake, improved interpretation of these data should incorporate the soil flux parameterizations suggested here.« less

  15. An inorganic CO2 diffusion and dissolution process explains negative CO2 fluxes in saline/alkaline soils.

    PubMed

    Ma, Jie; Wang, Zhong-Yuan; Stevenson, Bryan A; Zheng, Xin-Jun; Li, Yan

    2013-01-01

    An 'anomalous' negative flux, in which carbon dioxide (CO2) enters rather than is released from the ground, was studied in a saline/alkaline soil. Soil sterilization disclosed an inorganic process of CO2 dissolution into (during the night) and out of (during the day) the soil solution, driven by variation in soil temperature. Experimental and modeling analysis revealed that pH and soil moisture were the most important determinants of the magnitude of this inorganic CO2 flux. In the extreme cases of air-dried saline/alkaline soils, this inorganic process was predominant. While the diurnal flux measured was zero sum, leaching of the dissolved inorganic carbon in the soil solution could potentially effect net carbon ecosystem exchange. This finding implies that an inorganic module should be incorporated when dealing with the CO2 flux of saline/alkaline land. Neglecting this inorganic flux may induce erroneous or misleading conclusions in interpreting CO2 fluxes of these ecosystems.

  16. An inorganic CO2 diffusion and dissolution process explains negative CO2 fluxes in saline/alkaline soils

    PubMed Central

    Ma, Jie; Wang, Zhong-Yuan; Stevenson, Bryan A.; Zheng, Xin-Jun; Li, Yan

    2013-01-01

    An ‘anomalous' negative flux, in which carbon dioxide (CO2) enters rather than is released from the ground, was studied in a saline/alkaline soil. Soil sterilization disclosed an inorganic process of CO2 dissolution into (during the night) and out of (during the day) the soil solution, driven by variation in soil temperature. Experimental and modeling analysis revealed that pH and soil moisture were the most important determinants of the magnitude of this inorganic CO2 flux. In the extreme cases of air-dried saline/alkaline soils, this inorganic process was predominant. While the diurnal flux measured was zero sum, leaching of the dissolved inorganic carbon in the soil solution could potentially effect net carbon ecosystem exchange. This finding implies that an inorganic module should be incorporated when dealing with the CO2 flux of saline/alkaline land. Neglecting this inorganic flux may induce erroneous or misleading conclusions in interpreting CO2 fluxes of these ecosystems. PMID:23778238

  17. Resolving the Intricacies of Lateral Exports of Inorganic Carbon and Alkalinity from Coastal Salt Marshes

    NASA Astrophysics Data System (ADS)

    Wang, A. Z.; Chu, S. N.; Kroeger, K. D.; Gonneea, M. E.; Ganju, N. K.

    2017-12-01

    Dynamic lateral exports of dissolved inorganic carbon (DIC) and total alkalinity (Alk) via tidal exchange from highly productive intertidal marshes are an important piece of puzzle in the coastal carbon cycle, challenging our capability of assessing coastal carbon budgets and projecting future changes under anthropogenic pressure. The effects of these exports on seawater chemistry are profound yet complicated to study. This study presents the latest development of assessing lateral DIC and Alk fluxes from tidal marshes and examining their effects on seawater chemistry and coastal carbon budgets. The study evaluates different approaches to quantify these exports in order to obtain insights on the best and efficient way to capture the dynamics of such exports. A state-of-the-art DIC sensor, Channelized Optical System (CHANOS), was deployed to establish the true DIC fluxes. They are compared to the fluxes derived from empirical modeling and traditional bottle measurements. Salt marshes can acidify and alkalize tidal water by injecting CO2 (DIC) and Alk over a same tidal cycle. However, their generation is decoupled as a result of deferential effects of aerobic and anaerobic respirations. This creates complex scenarios of large swings of seawater chemistry and buffering capacity in tidal water over tidal and seasonal cycles. Marsh exports of DIC and Alk may have complex implications for the future, more acidified ocean. The latest estimates of marsh DIC and Alk exports suggest they are a major term in the marsh carbon budget and can be translated into one of the primary components in the coastal carbon cycle.

  18. Plankton copper requirements and uptake in the subarctic Northeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Semeniuk, David M.; Cullen, Jay T.; Johnson, W. Keith; Gagnon, Katie; Ruth, Thomas J.; Maldonado, Maria T.

    2009-07-01

    We undertook the first measurements of metabolic Cu requirements (net Cu:C assimilation ratios) and steady-state Cu uptake rates (ρCu ss) of natural plankton assemblages in the northeast subarctic Pacific using the short-lived radioisotope 67Cu. Size-fractionated net Cu:C assimilation ratios varied ˜3 fold (1.35-4.21 μmol Cu mol C -1) among the stations along Line P, from high Fe coastal waters to the Fe-limited open ocean. The variability in Cu:C was comparable to biogenic Fe:C ratios in this region. As previously observed for Fe uptake, the bacterial size class accounted for half of the total particulate ρCu ss. Interestingly, carbon biomass-normalized rates of Fe uptake from the siderophore desferrioxamine B (DFB) (ρFe DFB; a physiological proxy for Fe-limitation) by the >20 μm size class were positively correlated with the intracellular net Cu:C assimilation ratios in this size class, suggesting that intracellular Cu requirements for large phytoplankton respond to increased Fe-limitation. At Fe-limited Ocean Station Papa (OSP), we performed short-term Cu uptake (ρCu L) assays to determine the relative bioavailability of Cu bound to natural and synthetic ligands. Like the volumetric ρCu ss measured along Line P, the bacterial size class was responsible for at least 50% of the total ρCu L. Uptake rates of Cu from the various organic complexes suggest that Cu uptake was controlled by the oxidation state of the metal and by the metal:ligand concentration ratio, rather than the concentration of inorganic species of Cu in solution. Collectively, these data suggest that Cu likely plays an important role in the physiology of natural plankton communities beyond the toxicological effects studied previously.

  19. Inorganic Nanomaterials as Carriers for Drug Delivery.

    PubMed

    Chen, Shizhu; Hao, Xiaohong; Liang, Xingjie; Zhang, Qun; Zhang, Cuimiao; Zhou, Guoqiang; Shen, Shigang; Jia, Guang; Zhang, Jinchao

    2016-01-01

    For safe and effective therapy, drugs must be delivered efficiently and with minimal systemic side effects. Nanostructured drug carriers enable the delivery of small-molecule drugs as well as nucleic acids and proteins. Inorganic nanomaterials are ideal for drug delivery platforms due to their unique physicochemical properties, such as facile preparation, good storage stability and biocompatibility. Many inorganic nanostructure-based drug delivery platforms have been prepared. Although there are still many obstacles to overcome, significant advances have been made in recent years. This review focuses on the status and development of inorganic nanostructures, including silica, quantum dots, gold, carbon-based and magnetic iron oxide-based nanostructures, as carriers for chemical and biological drugs. We specifically highlight the extensive use of these inorganic drug carriers for cancer therapy. Finally, we discuss the most important areas in the field that urgently require further study.

  20. Improved cellular uptake of functionalized single-walled carbon nanotubes.

    PubMed

    Antonelli, A; Serafini, S; Menotta, M; Sfara, C; Pierigé, F; Giorgi, L; Ambrosi, G; Rossi, L; Magnani, M

    2010-10-22

    Single-walled carbon nanotubes (SWNTs) due to their unique structural and physicochemical properties, have been proposed as delivery systems for a variety of diagnostic and therapeutic agents. However, SWNTs have proven difficult to solubilize in aqueous solution, limiting their use in biological applications. In an attempt to improve SWNTs' solubility, biocompatibility, and to increase cell penetration we have thoroughly investigated the construction of carbon scaffolds coated with aliphatic carbon chains and phospholipids to obtain micelle-like structures. At first, oxidized SWNTs (2370 ± 30 nmol mg(-1) of SWNTs) were covalently coupled with an alcoholic chain (stearyl alcohol, C(18)H(37)OH; 816 nmol mg(-1) of SWNTs). Subsequently, SWNTs-COOC(18)H(37) derivatives were coated with phosphatidylethanolamine (PE) or -serine (PS) phospholipids obtaining micelle-like structures. We found that cellular uptake of these constructs by phagocytic cells occurs via an endocytotic mechanism for constructs larger than 400 nm while occurs via diffusion through the cell membrane for constructs up to 400 nm. The material that enters the cell by phagocytosis is actively internalized by macrophages and localizes inside endocytotic vesicles. In contrast the material that enters the cells by diffusion is found in the cell cytosol. In conclusion, we have realized new biomimetic constructs based on alkylated SWNTs coated with phospholipids that are efficiently internalized by different cell types only if their size is lower than 400 nm. These constructs are not toxic to the cells and could now be explored as delivery systems for non-permeant cargoes.

  1. Engineered in situ bioremediation of a petroleum hydrocarbon-contaminated aquifer: assessment of mineralization based on alkalinity, inorganic carbon and stable carbon isotope balances

    NASA Astrophysics Data System (ADS)

    Hunkeler, Daniel; Höhener, Patrick; Bernasconi, Stefano; Zeyer, Josef

    1999-04-01

    A concept is proposed to assess in situ petroleum hydrocarbon mineralization by combining data on oxidant consumption, production of reduced species, CH 4, alkalinity and dissolved inorganic carbon (DIC) with measurements of stable isotope ratios. The concept was applied to a diesel fuel contaminated aquifer in Menziken, Switzerland, which was treated by engineered in situ bioremediation. In the contaminated aquifer, added oxidants (O 2 and NO 3-) were consumed, elevated concentrations of Fe(II), Mn(II), CH 4, alkalinity and DIC were detected and the DIC was generally depleted in 13C compared to the background. The DIC production was larger than expected based on the consumption of dissolved oxidants and the production of reduced species. Stable carbon isotope balances revealed that the DIC production in the aquifer originated mainly from microbial petroleum hydrocarbon mineralization, and that geochemical reactions such as carbonate dissolution produced little DIC. This suggests that petroleum hydrocarbon mineralization can be underestimated if it is determined based on concentrations of dissolved oxidants and reduced species.

  2. Input of particulate organic and dissolved inorganic carbon from the Amazon to the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Druffel, E. R. M.; Bauer, J. E.; Griffin, S.

    2005-03-01

    We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC Δ14C results revealed postbomb carbon in river and ocean waters, with slightly higher values at the river mouth. The low DIC δ13C signature of the river end-member (-11‰) demonstrates that about half of the DIC originated from the remineralization of terrestrially derived organic matter. A linear relationship between DIC and salinity indicates that DIC was mixed nearly conservatively in the transition zone from the river mouth to the open ocean, though there was a small amount (≤10%) of organic matter remineralization in the mesohaline region. The POC Δ14C values in the river mouth were markedly lower than those values from the western Amazon region (Hedges et al., 1986). We conclude that the dominant source of POC near the river mouth and in the inner Amazon plume during November 1991 was aged, resuspended material of significant terrestrial character derived from shelf sediments, while the outer plume contained mainly marine-derived POC.

  3. Determination of the origin of dissolved inorganic carbon in groundwater around a reclaimed landfill in Otwock using stable carbon isotopes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Porowska, Dorota, E-mail: dorotap@uw.edu.pl

    Highlights: • Research showed the origin of DIC in the groundwater around a reclaimed landfill. • Carbon isotope was used to evaluate the contributions of carbon from different sources. • The leachate-contaminated water was isotopically distinct from the natural groundwater. • DIC in the natural groundwater comes from organic matter and dissolution of carbonates. • In the contaminated water, DIC comes from organic matter in the aquifer and landfill. - Abstract: Chemical and isotopic analyses of groundwater from piezometers located around a reclaimed landfill in Otwock (Poland) were performed in order to trace the origin of dissolved inorganic carbon (DIC)more » in the groundwater. Due to differences in the isotopic composition of carbon from different sources, an analysis of stable carbon isotopes in the groundwater, together with the Keeling plot approach and a two-component mixing model allow us to evaluate the relative contributions of carbon from these sources in the groundwater. In the natural (background) groundwater, DIC concentrations and the isotopic composition of DIC (δ{sup 13}C{sub DIC}) comes from two sources: decomposition of organic matter and carbonate dissolution within the aquifer sediments, whereas in the leachate-contaminated groundwater, DIC concentrations and δ{sup 13}C{sub DIC} values depend on the degradation of organic matter within the aquifer sediments and biodegradation of organic matter stored in the landfill. From the mixing model, about 4–54% of the DIC pool is derived from organic matter degradation and 96–46% from carbonate dissolution in natural conditions. In the leachate-contaminated groundwater, about 20–53% of the DIC is derived from organic matter degradation of natural origin and 80–47% from biodegradation of organic matter stored in the landfill. Partial pressure of CO{sub 2} (P CO{sub 2}) was generally above the atmospheric, hence atmospheric CO{sub 2} as a source of carbon in DIC pool was negligible

  4. Independent Colimitation for Carbon Dioxide and Inorganic Phosphorus

    PubMed Central

    Spijkerman, Elly; de Castro, Francisco; Gaedke, Ursula

    2011-01-01

    Simultaneous limitation of plant growth by two or more nutrients is increasingly acknowledged as a common phenomenon in nature, but its cellular mechanisms are far from understood. We investigated the uptake kinetics of CO2 and phosphorus of the algae Chlamydomonas acidophila in response to growth at limiting conditions of CO2 and phosphorus. In addition, we fitted the data to four different Monod-type models: one assuming Liebigs Law of the minimum, one assuming that the affinity for the uptake of one nutrient is not influenced by the supply of the other (independent colimitation) and two where the uptake affinity for one nutrient depends on the supply of the other (dependent colimitation). In addition we asked whether the physiological response under colimitation differs from that under single nutrient limitation. We found no negative correlation between the affinities for uptake of the two nutrients, thereby rejecting a dependent colimitation. Kinetic data were supported by a better model fit assuming independent uptake of colimiting nutrients than when assuming Liebigs Law of the minimum or a dependent colimitation. Results show that cell nutrient homeostasis regulated nutrient acquisition which resulted in a trade-off in the maximum uptake rates of CO2 and phosphorus, possibly driven by space limitation on the cell membrane for porters for the different nutrients. Hence, the response to colimitation deviated from that to a single nutrient limitation. In conclusion, responses to single nutrient limitation cannot be extrapolated to situations where multiple nutrients are limiting, which calls for colimitation experiments and models to properly predict growth responses to a changing natural environment. These deviations from single nutrient limitation response under colimiting conditions and independent colimitation may also hold for other nutrients in algae and in higher plants. PMID:22145031

  5. Atmospheric Mg2+ wet deposition within the continental United States and implications for soil inorganic carbon sequestration

    NASA Astrophysics Data System (ADS)

    Goddard, Megan A.; Mikhailova, Elena A.; Post, Christopher J.; Schlautman, Mark A.

    2007-02-01

    Little is known about atmospheric magnesium ion (Mg2+) wet deposition in relation to soil inorganic carbon sequestration. Understanding the conversion of carbon dioxide (CO2) or organic carbon to a form having a long residence time within the soil (e.g., dolomite, magnesian calcite) will greatly benefit agriculture, industry, and society on a global scale. This preliminary study was conducted to analyze atmospheric Mg2+ wet deposition within the continental United States (U.S.) and to rank the twelve major soil orders in terms of average annual atmospheric Mg2+ wet deposition. The total average annual Mg2+ wet deposition for each soil order was estimated with geographic information systems (GIS) using the following data layers: (1) atmospheric Mg2+ wet deposition data layers covering the continental U.S. for a 10-yr period (1994-2003) and (2) a soil order data layer derived from a national soils database. A map of average annual Mg2+ wet deposition for 1994-2003 reveals that the highest deposition (0.75-1.41 kg ha-1) occurred in Oregon, Washington, parts of California, and the coastal areas of East Coast states due to magnesium enrichment of atmospheric deposition from sea salt. The Midwestern region of the U.S. received about 0.25-0.75 kg ha-1 Mg2+ wet deposition annually, which was associated with loess derived soils, occurrence of dust storms and possibly fertilization. The soil orders receiving the highest average annual atmospheric Mg2+ wet deposition from 1994 to 2003 were: (1) Mollisols (3.7 × 107 kg), (2) Alfisols (3.6 × 107 kg) and (3) Ultisols (2.8 × 107 kg). In terms of potential soil carbon sequestration, the average annual atmospheric Mg2+ wet deposition was equivalent to formation of the following theoretical amounts of dolomite: (1) Mollisols (2.8 × 108 kg of CaMg(CO3)2), (2) Alfisols (2.7 × 108 kg of CaMg(CO3)2) and (3) Ultisols (2.1 × 108 kg of CaMg(CO3)2). The soil orders receiving the lowest average annual atmospheric Mg2+ wet deposition

  6. Controls on the Origin and Cycling of Riverine Dissolved Inorganic Carbon in the Brazos River, Texas

    NASA Astrophysics Data System (ADS)

    Zeng, F.; Masiello, C. A.; Hockaday, W. C.

    2008-12-01

    Rivers are generally supersaturated in CO2 with respect to the atmosphere. However, there is little agreement on the sources and turnover times of excess CO2 in river waters. This is likely due to varying dominant controls on carbon sources (e.g. geologic setting, climate, land use, or human activities). In this study, we measured carbon isotopic signatures (δ13C and Δ14C) of riverine dissolved inorganic carbon (DIC), as well as solid state cross polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) of particulate organic carbon (POC), to determine carbon sources fuelling respiration of the Brazos River in Texas. We found that sources of riverine CO2 varied significantly along the length of the Brazos. In the middle Brazos (between Graham and Waco), which is partially underlain by limestone, riverine DIC had average Δ14C of 74 ‰ and δ13C of -7.5 ‰, suggesting that riverine CO2 is derived almost entirely from contemporary carbon (less than 5 years old) with little evidence of carbonate input, probably due to the damming upstream of Waco. In the lower Brazos (downstream of Bryan), riverine DIC was highly depleted in 14C (average Δ14C = -148.5 ‰) and enriched in 13C (average δ13C= -9.32 ‰), indicative of the presence of old carbonate. Since there is no carbonate bedrock in contact with the river in this area, the most likely source of old carbonate is the shell used in road and building construction throughout the 19th century. Our results suggest that the effect of human activities superimposes and even surpasses the effect of natural controls (e.g. geologic setting and climate) on C cycling in the Brazos.

  7. The global distribution of leaf chlorophyll content and seasonal controls on carbon uptake

    NASA Astrophysics Data System (ADS)

    Croft, H.; Chen, J. M.; Luo, X.; Bartlett, P. A.; Staebler, R. M.; He, L.; Mo, G.; Luo, S.; Simic, A.; Arabian, J.; He, Y.; Zhang, Y.; Beringer, J.; Hutley, L. B.; Noland, T. L.; Arellano, P.; Stahl, C.; Homolová, L.; Bonal, D.; Malenovský, Z.; Yi, Q.; Amiri, R.

    2017-12-01

    Leaf chlorophyll (ChlLeaf) is crucial to biosphere-atmosphere exchanges of carbon and water, and the functioning of terrestrial ecosystems. Improving the accuracy of modelled photosynthetic carbon uptake is a central priority for understanding ecosystem response to a changing climate. A source of uncertainty within gross primary productivity (GPP) estimates is the failure to explicitly consider seasonal controls on leaf photosynthetic potential. Whilst the inclusion of ChlLeafinto carbon models has shown potential to provide a physiological constraint, progress has been hampered by the absence of a spatially-gridded, global chlorophyll product. Here, we present the first spatially-continuous, global view of terrestrial ChlLeaf, at weekly intervals. Satellite-derived ChlLeaf was modelled using a physically-based radiative transfer modelling approach, with a two stage model inversion method. 4-Scale and SAIL canopy models were first used to model leaf-level reflectance from ENIVSAT MERIS 300m satellite data. The PROSPECT leaf model was then used to derive ChlLeaf from the modelled leaf reflectance. This algorithm was validated using measured ChlLeaf data from 248 measurements within 26 field locations, covering six plant functional types (PFTs). Modelled results show very good relationships with measured data, particularly for deciduous broadleaf forests (R2 = 0.67; p<0.001) and croplands (R2 = 0.42; p<000.1). With all PFTs considered together, the overall validation against measured data was strong (R2 = 0.50; p<0.001). The incorporation of chlorophyll within a light-use efficiency GPP modelling approach and a Terrestrial Biosphere Model demonstrated that neglecting to account for seasonality in leaf physiology resulted in over-estimations in GPP at the start/end of a deciduous growing season, due to a divergence in canopy structure and leaf function. Across nine PFTs, Fluxnet eddy-covariance data was used to validate TBM GPP estimates using Chl

  8. 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.

  9. Selection and Screening of DNA Aptamers for Inorganic Nanomaterials.

    PubMed

    Zhou, Yibo; Huang, Zhicheng; Yang, Ronghua; Liu, Juewen

    2018-02-21

    Searching for DNA sequences that can strongly and selectively bind to inorganic surfaces is a long-standing topic in bionanotechnology, analytical chemistry and biointerface research. This can be achieved either by aptamer selection starting with a very large library of ≈10 14 random DNA sequences, or by careful screening of a much smaller library (usually from a few to a few hundred) with rationally designed sequences. Unlike typical molecular targets, inorganic surfaces often have quite strong DNA adsorption affinities due to polyvalent binding and even chemical interactions. This leads to a very high background binding making aptamer selection difficult. Screening, on the other hand, can be designed to compare relative binding affinities of different DNA sequences and could be more appropriate for inorganic surfaces. The resulting sequences have been used for DNA-directed assembly, sorting of carbon nanotubes, and DNA-controlled growth of inorganic nanomaterials. It was recently discovered that poly-cytosine (C) DNA can strongly bind to a diverse range of nanomaterials including nanocarbons (graphene oxide and carbon nanotubes), various metal oxides and transition-metal dichalcogenides. In this Concept article, we articulate the need for screening and potential artifacts associated with traditional aptamer selection methods for inorganic surfaces. Representative examples of application are discussed, and a few future research opportunities are proposed towards the end of this article. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Organic and inorganic components of aerosols over the central Himalayas: winter and summer variations in stable carbon and nitrogen isotopic composition.

    PubMed

    Hegde, Prashant; Kawamura, Kimitaka; Joshi, H; Naja, M

    2016-04-01

    The aerosol samples were collected from a high elevation mountain site, Nainital, in India (1958 m asl) during September 2006 to June 2007 and were analyzed for water-soluble inorganic species, total carbon, nitrogen, and their isotopic composition (δ(13)C and δ(15)N, respectively). The chemical and isotopic composition of aerosols revealed significant anthropogenic influence over this remote free-troposphere site. The amount of total carbon and nitrogen and their isotopic composition suggest a considerable contribution of biomass burning to the aerosols during winter. On the other hand, fossil fuel combustion sources are found to be dominant during summer. The carbon aerosol in winter is characterized by greater isotope ratios (av. -24.0‰), mostly originated from biomass burning of C4 plants. On the contrary, the aerosols in summer showed smaller δ(13)C values (-26.0‰), indicating that they are originated from vascular plants (mostly of C3 plants). The secondary ions (i.e., SO4 (2-), NH4 (+), and NO3 (-)) were abundant due to the atmospheric reactions during long-range transport in both seasons. The water-soluble organic and inorganic compositions revealed that they are aged in winter but comparatively fresh in summer. This study validates that the pollutants generated from far distant sources could reach high altitudes over the Himalayan region under favorable meteorological conditions.

  11. Inorganic carbon and oxygen dynamics in a marsh‐dominated estuary

    PubMed Central

    Di Iorio, Daniela; Cai, Wei‐Jun; Hopkinson, Charles S.

    2017-01-01

    Abstract We conducted a free‐water mass balance‐based study to address the rate of metabolism and net carbon exchange for the tidal wetland and estuarine portion of the coastal ocean and the uncertainties associated with this approach were assessed. We measured open water diurnal O2 and dissolved inorganic carbon (DIC) dynamics seasonally in a salt marsh‐estuary in Georgia, U.S.A. with a focus on the marsh‐estuary linkage associated with tidal flooding. We observed that the overall estuarine system was a net source of CO2 to the atmosphere and coastal ocean and a net sink for oceanic and atmospheric O2. Rates of metabolism were extremely high, with respiration (43 mol m−2 yr−1) greatly exceeding gross primary production (28 mol m−2 yr−1), such that the overall system was net heterotrophic. Metabolism measured with DIC were higher than with O2, which we attribute to high rates of anaerobic respiration and reduced sulfur storage in salt marsh sediments, and we assume substantial levels of anoxygenic photosynthesis. We found gas exchange from a flooded marsh is substantial, accounting for about 28% of total O2 and CO2 air–water exchange. A significant percentage of the overall estuarine aquatic metabolism is attributable to metabolism of marsh organisms during inundation. Our study suggests not rely on oceanographic stoichiometry to convert from O2 to C based measurements when constructing C balances for the coastal ocean. We also suggest eddy covariance measurements of salt marsh net ecosystem exchange underestimate net ecosystem production as they do not account for lateral DIC exchange associated with marsh tidal inundation. PMID:29456267

  12. Weakening temperature control on the interannual variations of spring carbon uptake across northern lands

    NASA Astrophysics Data System (ADS)

    Piao, S.; Peng, S.; Liu, Z.; Ciais, P.; Wang, T.; Huang, M.; Ahlstrom, A.; Burkhart, J. F.; Chevallier, F.; Jeong, S. J.; Janssens, I. A.; Lin, X.; Mao, J.; Myneni, R.; Shi, X.; van der Velde, I. R.; Stohl, A.; Mohammat, A.; Yao, Y.; Peñuelas, J.; Zhu, Z.; Tans, P. P.

    2017-12-01

    Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems. Here we use 34 years of atmospheric CO2 concentration measurements at Barrow, Alaska (BRW, 71o N) to show that the interannual relationship between spring temperature and carbon uptake has recently shifted. We use two indicators: the spring zero-crossing date of atmospheric CO2 (SZC) and the magnitude of CO2 draw down between May and June (SCC). The previously reported strong correlation between SZC, SCC and spring land temperature (ST) was found in the first 17 years of measurements, but disappeared in the last 17 years. As a result, the sensitivity of both SZC and SCC to warming decreased. Simulations with an atmospheric transport model coupled to a terrestrial ecosystem model suggest that the weakened interannual correlation of SZC and SCC with ST in the last 17 years is attributable to the declining temperature response of spring net primary productivity (NPP) rather than to changes in heterotrophic respiration or in atmospheric transport patterns. Reduced chilling during dormancy and emerging light limitation are possible mechanisms that may have contributed to the loss of NPP response to ST. Our results thus challenge the `warmer spring-bigger sink' mechanism.

  13. Weakening temperature control on the interannual variations of spring carbon uptake across northern lands

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Piao, Shilong; Liu, Zhuo; Wang, Tao

    2017-04-24

    Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems. We use 34 years of atmospheric CO 2 concentration measurements at Barrow, Alaska (BRW, 71° N) to show that the interannual relationship between spring temperature and carbon uptake has recently shifted. Here, we use two indicators: the spring zero-crossing date of atmospheric CO 2 (SZC) and the magnitude of CO 2 drawdown between May and June (SCC). The previously reported strong correlation between SZC, SCC and spring land temperature (ST) was found in the first 17 years of measurements, but disappeared in the lastmore » 17 years. As a result, the sensitivity of both SZC and SCC to warming decreased. Simulations with an atmospheric transport model coupled to a terrestrial ecosystem model suggest that the weakened interannual correlation of SZC and SCC with ST in the last 17 years is attributable to the declining temperature response of spring net primary productivity (NPP) rather than to changes in heterotrophic respiration or in atmospheric transport patterns. Reduced chilling during dormancy and emerging light limitation are possible mechanisms that may have contributed to the loss of NPP response to ST. These results thus challenge the ‘warmer spring–bigger sink’ mechanism.« less

  14. The electrochemical performance of super P carbon black in reversible Li/Na ion uptake

    NASA Astrophysics Data System (ADS)

    Peng, Bo; Xu, Yaolin; Wang, Xiaoqun; Shi, Xinghua; Mulder, Fokko M.

    2017-06-01

    Super P carbon black (SPCB) has been widely used as a conducting additive in Li/Na ion batteries to improve the electronic conductivity. However, there has not yet been a comprehensive study on its structure and electrochemical properties for Li/Na ion uptake, though it is important to characterize its contribution in any study of active materials that uses this additive in non-negligible amounts. In this article the structure of SPCB has been characterized and a comprehensive study on the electrochemical Li/Na ion uptake capability and reaction mechanisms are reported. SPCB exhibits a considerable lithiation capacity (up to 310 mAh g-1) from the Li ion intercalation in the graphite structure. Sodiation in SPCB undergoes two stages: Na ion intercalation into the layers between the graphene sheets and the Na plating in the pores between the nano-graphitic domains, and a sodiation capacity up to 145 mAh g-1 has been achieved. Moreover, the influence of the type and content of binders on the lithiation and sodiation properties has been investigated. The cycling stability is much enhanced with sodium carboxymethyl cellulose (NaCMC) binder in the electrode and fluoroethylene carbonate (FEC) in the electrolyte; and a higher content of binder improves the Coulombic efficiency during dis-/charge.

  15. Growth, characterization and post-processing of inorganic and hybrid organic-inorganic thin films deposited using atomic and molecular layer deposition techniques

    NASA Astrophysics Data System (ADS)

    Abdulagatov, Aziz Ilmutdinovich

    Atomic layer deposition (ALD) and molecular layer deposition (MLD) are advanced thin film coating techniques developed for deposition of inorganic and hybrid organic-inorganic films respectively. Decreasing device dimensions and increasing aspect ratios in semiconductor processing has motivated developments in ALD. The beginning of this thesis will cover study of new ALD chemistry for high dielectric constant Y 2O3. In addition, the feasibility of conducting low temperature ALD of TiN and TiAlN is explored using highly reactive hydrazine as a new nitrogen source. Developments of these ALD processes are important for the electronics industry. As the search for new materials with more advanced properties continues, attention has shifted toward exploring the synthesis of hierarchically nanostructured thin films. Such complex architectures can provide novel functions important to the development of state of the art devices for the electronics industry, catalysis, energy conversion and memory storage as a few examples. Therefore, the main focus of this thesis is on the growth, characterization, and post-processing of ALD and MLD films for fabrication of novel composite (nanostructured) thin films. Novel composite materials are created by annealing amorphous ALD oxide alloys in air and by heat treatment of hybrid organic-inorganic MLD films in inert atmosphere (pyrolysis). The synthesis of porous TiO2 or Al2O3 supported V2O5 for enhanced surface area catalysis was achieved by the annealing of inorganic TiVxOy and AlV xOy ALD films in air. The interplay between phase separation, surface energy difference, crystallization, and melting temperature of individual oxides were studied for their control of film morphology. In other work, a class of novel metal oxide-graphitic carbon composite thin films was produced by pyrolysis of MLD hybrid organic-inorganic films. For example, annealing in argon of titania based hybrid films enabled fabrication of thin films of intimately

  16. Adsorption of arsenite and selenite using an inorganic ion exchanger based on Fe-Mn hydrous oxide.

    PubMed

    Szlachta, Małgorzata; Gerda, Vasyl; Chubar, Natalia

    2012-01-01

    The adsorption behaviour and mechanism of As(III) and Se(IV) oxyanion uptake using a mixed inorganic adsorbent were studied. The novel adsorbent, based on Fe(III)-Mn(III) hydrous oxides and manganese(II) carbonate, was synthesised using a hydrothermal precipitation approach in the presence of urea. The inorganic ion exchanger exhibited a high selectivity and adsorptive capacity towards As(III) (up to 47.6 mg/g) and Se(IV) (up to 29.0 mg/g), even at low equilibrium concentration. Although pH effects were typical for anionic species (i.e., the adsorption decreased upon pH increase), Se(IV) was more sensitive to pH changes than As(III). The rates of adsorption of both oxyanions were high. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) studies showed that the ion exchange adsorption of both anions took place via OH(-) groups, mainly from Fe(III) but also Mn(III) hydrous oxides. MnCO(3) did not contribute directly to As(III) and Se(IV) removal. A higher adsorptive capacity of the developed material towards As(III) was partly due to partial As(III) oxidation during adsorption. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Phytotoxicity and uptake of roxarsone by wheat (Triticum aestivum L.) seedlings.

    PubMed

    Fu, Qing-Long; Blaney, Lee; Zhou, Dong-Mei

    2016-12-01

    Roxarsone (ROX), the primary aromatic arsenical additive (AAA) used in animal feeding operations, is of increasing concern to environmental and human health due to land application of ROX-laden animal manure. Few studies have investigated the phytotoxicity, uptake mechanisms, and speciation of AAA in crop plants. In this study, wheat seedlings were employed to address these issues under hydroponic conditions. Compared to inorganic arsenic, ROX was less toxic to wheat root elongation. Wheat roots were more sensitive to ROX stress than shoots. For the first time, metabolized inorganic arsenic was detected in plants, although ROX was the predominant detected arsenic species in wheat seedlings. ROX uptake and toxicity to roots were inhibited by humic acid at concentrations higher than 50 mg/L due to interaction with ROX. Phosphate enhanced ROX uptake, but no trends were observed for ROX uptake in the presence of glycerol at concentrations lower than 250 mM. In addition, ROX uptake was significantly decreased by silicate (Si(IV), 0.5-10 mM) and the metabolic inhibitor, 2,4-dinitrophenol (0.5-2 mM), indicating that ROX transport into wheat roots was actively mediated by Si(IV)-sensitive transporters. These findings provide important insights into the fate and speciation of AAA in soil-water-plant systems relevant to human health. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. A robust and fast method of sampling and analysis of delta13C of dissolved inorganic carbon in ground waters.

    PubMed

    Spötl, Christoph

    2005-09-01

    The stable carbon isotopic composition of dissolved inorganic carbon (delta13C(DIC)) is traditionally determined using either direct precipitation or gas evolution methods in conjunction with offline gas preparation and measurement in a dual-inlet isotope ratio mass spectrometer. A gas evolution method based on continuous-flow technology is described here, which is easy to use and robust. Water samples (100-1500 microl depending on the carbonate alkalinity) are injected into He-filled autosampler vials in the field and analysed on an automated continuous-flow gas preparation system interfaced to an isotope ratio mass spectrometer. Sample analysis time including online preparation is 10 min and overall precision is 0.1 per thousand. This method is thus fast and can easily be automated for handling large sample batches.

  19. [Carbon monoxide tests in a steady state. Uptake and transfer capacity, normal values and lower limits].

    PubMed

    Ramonatxo, M; Préfaut, C; Guerrero, H; Moutou, H; Bansard, X; Chardon, G

    1982-01-01

    The aim of this study was to establish data which would best demonstrate the variations of different tests using Carbon Monoxide as a tracer gas (total and partial functional uptake coefficient and transfer capacity) to establish mean values and lower limits of normal of these tests. Multivariate statistical analysis was used; in the first stage a connection was sought between the fractional uptake coefficient (partial and total) to other parameters, comparing subjects and data. In the second stage the comparison was refined by eliminating the least useful data, trying, despite a small loss of material, to reveal the most important connections, linear or otherwise. The fractional uptake coefficients varied according to sex, also the variation of the partial alveolar-expired fractional uptake equivalent (DuACO) was largely a function of respiratory rate and tidal volume. The alveolar-arterial partial fractional uptake equivalent (DuaCO) depended more on respiratory frequency and age. Finally the total fractional uptake coefficient (DuCO) and the transfer capacity corrected per liter of ventilation (TLCO/V) were functions of these parameters. The last stage of this work, after taking account of the statistical observations consistent with the facts of these physiological hypotheses led to a search for a better way of approaching the laws linking the collected data to the fractional uptake coefficient. The lower limits of normal were arbitrarily defined, separating those 5% of subjects deviating most strongly from the mean. As a result, the relationship between the lower limit of normal and the theoretical mean value was 90% for the partial and total fractional uptake coefficient and 70% for the transfer capacity corrected per liter of ventilation.

  20. Intertidal salt marshes as an important source of inorganic carbon to the coastal ocean

    USGS Publications Warehouse

    Wang, Zhaohui Aleck; Kroeger, Kevin D.; Ganju, Neil K.; Gonneea, Meagan; Chu, Sophie N.

    2016-01-01

    Dynamic tidal export of dissolved inorganic carbon (DIC) to the coastal ocean from highly productive intertidal marshes and its effects on seawater carbonate chemistry are thoroughly evaluated. The study uses a comprehensive approach by combining tidal water sampling of CO2parameters across seasons, continuous in situ measurements of biogeochemically-relevant parameters and water fluxes, with high-resolution modeling in an intertidal salt marsh of the U.S. northeast region. Salt marshes can acidify and alkalize tidal water by injecting CO2 (DIC) and total alkalinity (TA). DIC and TA generation may also be decoupled due to differential effects of marsh aerobic and anaerobic respiration on DIC and TA. As marsh DIC is added to tidal water, the buffering capacity first decreases to a minimum and then increases quickly. Large additions of marsh DIC can result in higher buffering capacity in ebbing tide than incoming tide. Alkalization of tidal water, which mostly occurs in the summer due to anaerobic respiration, can further modify buffering capacity. Marsh exports of DIC and alkalinity may have complex implications for the future, more acidified ocean. Marsh DIC export exhibits high variability over tidal and seasonal cycles, which is modulated by both marsh DIC generation and by water fluxes. The marsh DIC export of 414 g C m−2 yr−1, based on high-resolution measurements and modeling, is more than twice the previous estimates. It is a major term in the marsh carbon budget and translates to one of the largest carbon fluxes along the U.S. East Coast.

  1. Sol-gel coating of inorganic nanostructures with resorcinol-formaldehyde resin.

    PubMed

    Li, Na; Zhang, Qiao; Liu, Jian; Joo, Jibong; Lee, Austin; Gan, Yang; Yin, Yadong

    2013-06-07

    A general sol-gel process has been developed to form a coating of resorcinol-formaldehyde (RF) resin on inorganic nanostructures of various compositions and morphologies. The RF shell can be conveniently converted into carbon through high temperature carbonization under an inert atmosphere.

  2. Carbon uptake and biogeochemical change in the Southern Ocean, south of Tasmania

    NASA Astrophysics Data System (ADS)

    Conde Pardo, Paula; Tilbrook, Bronte; Langlais, Clothilde; Trull, Thomas William; Rich Rintoul, Stephen

    2017-11-01

    Biogeochemical change in the water masses of the Southern Ocean, south of Tasmania, was assessed for the 16-year period between 1995 and 2011 using data from four summer repeats of the WOCE-JGOFS-CLIVAR-GO-SHIP (Key et al., 2015; Olsen et al., 2016) SR03 hydrographic section (at ˜ 140° E). Changes in temperature, salinity, oxygen, and nutrients were used to disentangle the effect of solubility, biology, circulation and anthropogenic carbon (CANT) uptake on the variability of dissolved inorganic carbon (DIC) for eight water mass layers defined by neutral surfaces (γn). CANT was estimated using an improved back-calculation method. Warming (˜ 0.0352 ± 0.0170 °C yr-1) of Subtropical Central Water (STCW) and Antarctic Surface Water (AASW) layers decreased their gas solubility, and accordingly DIC concentrations increased less rapidly than expected from equilibration with rising atmospheric CO2 (˜ 0.86 ± 0.16 µmol kg-1 yr-1 versus ˜ 1 ± 0.12 µmol kg-1 yr-1). An increase in apparent oxygen utilisation (AOU) occurred in these layers due to either remineralisation of organic matter or intensification of upwelling. The range of estimates for the increases in CANT were 0.71 ± 0.08 to 0.93 ± 0.08 µmol kg-1 yr-1 for STCW and 0.35 ± 0.14 to 0.65 ± 0.21 µmol kg-1 yr-1 for AASW, with the lower values in each water mass obtained by assigning all the AOU change to remineralisation. DIC increases in the Sub-Antarctic Mode Water (SAMW, 1.10 ± 0.14 µmol kg-1 yr-1) and Antarctic Intermediate Water (AAIW, 0.40 ± 0.15 µmol kg-1 yr-1) layers were similar to the calculated CANT trends. For SAMW, the CANT increase tracked rising atmospheric CO2. As a consequence of the general DIC increase, decreases in total pH (pHT) and aragonite saturation (ΩAr) were found in most water masses, with the upper ocean and the SAMW layer presenting the largest trends for pHT decrease (˜ -0.0031 ± 0.0004 yr-1). DIC increases in deep and bottom layers (˜ 0.24 ± 0.04 µmol kg-1 yr-1

  3. Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity

    PubMed Central

    Brackin, Richard; Näsholm, Torgny; Robinson, Nicole; Guillou, Stéphane; Vinall, Kerry; Lakshmanan, Prakash; Schmidt, Susanne; Inselsbacher, Erich

    2015-01-01

    Globally only ≈50% of applied nitrogen (N) fertilizer is captured by crops, and the remainder can cause pollution via runoff and gaseous emissions. Synchronizing soil N supply and crop demand will address this problem, however current soil analysis methods provide little insight into delivery and acquisition of N forms by roots. We used microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure N fluxes in sugarcane cropping soils receiving different fertilizer regimes, and compare these with N uptake capacities of sugarcane roots. We show that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots’ uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that (i) the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N, and (ii) organic N may contribute more to crop N supply than is currently assumed. PMID:26496834

  4. Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity

    NASA Astrophysics Data System (ADS)

    Inselsbacher, Erich; Schmidt, Susanne; Näsholm, Torgny; Robinson, Nicole; Guillou, Stéphane; Vinall, Kerry; Lakshmanan, Prakash; Brackin, Richard

    2016-04-01

    Nitrogen (N) uptake by agricultural crops is a key constituent of the global N cycle, as N captured by roots has a markedly different fate than N remaining in the soil. Global evidence indicates that only approximately 50% of applied N fertilizer is captured by crops, and the remainder can cause pollution via runoff and gaseous emissions. This inefficiency is of global concern, and requires innovation based on improved understanding of which N forms are available for and ultimately taken up by crops. However, current soil analysis methods based on destructive soil sampling provide little insight into delivery and acquisition of N forms by roots. Here, we present the results of a study in sugarcane fields receiving different fertilizer regimes comparing soil N supply rates with potential root N uptake rates. We applied microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure flux rates of inorganic N and amino acid N, and analyzed N uptake capacities of sugarcane roots using 15N labelled tracers. We found that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots' uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N, and organic N may contribute more to crop N supply than is currently assumed. Overall, we show a new approach for examining in situ N relations in soil in context of crop N physiology, which provides a new avenue towards tailoring N fertilizer supply to match the specific uptake abilities and N demand of crops over the growth

  5. Long-term, high-spatial resolution carbon balance monitoring of the Amazonian frontier: Predisturbance and postdisturbance carbon emissions and uptake

    NASA Astrophysics Data System (ADS)

    Toomey, Michael; Roberts, Dar A.; Caviglia-Harris, Jill; Cochrane, Mark A.; Dewes, Candida F.; Harris, Daniel; Numata, Izaya; Sales, Marcio H.; Sills, Erin; Souza, Carlos M.

    2013-06-01

    We performed high-spatial and high-temporal resolution modeling of carbon stocks and fluxes in the state of Rondônia, Brazil for the period 1985-2009, using annual Landsat-derived land cover classifications and a modified bookkeeping modeling approach. According to these results, Rondônia contributed 3.5-4% of pantropical humid forest deforestation emissions over this period. Similar to well-known figures reported by the Brazilian Space Agency, we found a decline in deforestation rates since 2006. However, we estimate a lesser decrease, with deforestation rates continuing at levels similar to the early 2000s. Forest carbon stocks declined at an annual rate of 1.51%; emissions from postdisturbance land use nearly equaled those of the initial deforestation events. Carbon uptake by secondary forest was negligible due to limited spatial extent and high turnover rates. Net carbon emissions represented 93% of initial forest carbon stocks, due in part to repeated slash and pasture burnings and secondary forest clearing. We analyzed potential error incurred when spatially aggregating land cover by comparing results based on coarser-resolution (250 m) and full-resolution land cover products. At the coarser resolution, more than 90% of deforestation and secondary forest would be unresolvable, assuming that a 50% change threshold is necessary for detection. Therefore, we strongly suggest the use of Landsat-scale ( 30m) resolution carbon monitoring in tropical regions dominated by nonmechanized, smallholder land use change.

  6. TOPICAL REVIEW Recent developments in inorganically filled carbon nanotubes: successes and challenges

    NASA Astrophysics Data System (ADS)

    Gautam, Ujjal K.; Costa, Pedro M. F. J.; Bando, Yoshio; Fang, Xiaosheng; Li, Liang; Imura, Masataka; Golberg, Dmitri

    2010-10-01

    Carbon nanotubes (CNTs) are a unique class of nanomaterials that can be imagined as rolled graphene sheets. The inner hollow of a CNT provides an extremely small, one-dimensional space for storage of materials. In the last decade, enormous effort has been spent to produce filled CNTs that combine the properties of both the host CNT and the guest filling material. CNTs filled with various inorganic materials such as metals, alloys, semiconductors and insulators have been obtained using different synthesis approaches including capillary filling and chemical vapor deposition. Recently, several potential applications have emerged for these materials, such as the measurement of temperature at the nanoscale, nano-spot welding, and the storage and delivery of extremely small quantities of materials. A clear distinction between this class of materials and other nanostructures is the existence of an enormous interfacial area between the CNT and the filling matter. Theoretical investigations have shown that the lattice mismatch and strong exchange interaction of CNTs with the guest material across the interface should result in reordering of the guest crystal structure and passivation of the surface dangling bonds and thus yielding new and interesting physical properties. Despite preliminary successes, there remain many challenges in realizing applications of CNTs filled with inorganic materials, such as a comprehensive understanding of their growth and physical properties and control of their structural parameters. In this article, we overview research on filled CNT nanomaterials with special emphasis on recent progress and key achievements. We also discuss the future scope and the key challenges emerging out of a decade of intensive research on these fascinating materials.

  7. Carbon nanotubes enhance CpG uptake and potentiate antiglioma immunity.

    PubMed

    Zhao, Dongchang; Alizadeh, Darya; Zhang, Leying; Liu, Wei; Farrukh, Omar; Manuel, Edwin; Diamond, Don J; Badie, Behnam

    2011-02-15

    Stimulation of toll-like receptor-9 (TLR9) by CpG oligodeoxynucleotides (CpG) has been shown to counteract the immunosuppressive microenvironment and to inhibit tumor growth in glioma models. Because TLR9 is located intracellularly, we hypothesized that methods that enhance its internalization may also potentiate its immunostimulatory response. The goal of this study was to evaluate carbon nanotubes (CNT) as a CpG delivery vehicle in brain tumor models. Functionalized single-walled CNTs were conjugated with CpG (CNT-CpG) and evaluated in vitro and in mice bearing intracranial GL261 gliomas. Flow cytometry was used to assess CNT-CpG uptake and antiglioma immune response. Tumor growth was measured by bioluminescent imaging, histology, and animal survival. CNT-CpG was nontoxic and enhanced CpG uptake both in vitro and intracranial gliomas. CNT-mediated CpG delivery also potentiated proinflammatory cytokine production by primary monocytes. Interestingly, a single intracranial injection of low-dose CNT-CpG (but not free CpG or blank CNT) eradicated intracranial GL261 gliomas in half of tumor-bearing mice. Moreover, surviving animals exhibited durable tumor-free remission (>3 months), and were protected from intracranial tumor rechallenge, demonstrating induction of long-term antitumor immunity. These findings suggest that CNTs can potentiate CpG immunopotency by enhancing its delivery into tumor-associated inflammatory cells. ©2010 AACR.

  8. Recent advances in inorganic nanoparticle-based drug delivery systems.

    PubMed

    Murakami, Tatsuya; Tsuchida, Kunihiro

    2008-02-01

    Drug delivery systems, designed to enhance drug efficacy and reduce their adverse effects, have evolved accompanied by the development of novel materials. Nanotechnology is an emerging scientific area that has created a variety of intriguing inorganic nanoparticles. In this review, we focus on the feasibility of inorganic nanoparticles, including iron oxide nanoparticles, gold nanoparticles, fullerenes and carbon nanohorns, as drug carriers, and summarize recent advances in this field.

  9. Drivers of inorganic carbon dynamics in first-year sea ice: A model study

    NASA Astrophysics Data System (ADS)

    Moreau, Sébastien; Vancoppenolle, Martin; Delille, Bruno; Tison, Jean-Louis; Zhou, Jiayun; Kotovitch, Marie; Thomas, David N.; Geilfus, Nicolas-Xavier; Goosse, Hugues

    2015-01-01

    Sea ice is an active source or a sink for carbon dioxide (CO2), although to what extent is not clear. Here, we analyze CO2 dynamics within sea ice using a one-dimensional halothermodynamic sea ice model including gas physics and carbon biogeochemistry. The ice-ocean fluxes, and vertical transport, of total dissolved inorganic carbon (DIC) and total alkalinity (TA) are represented using fluid transport equations. Carbonate chemistry, the consumption, and release of CO2 by primary production and respiration, the precipitation and dissolution of ikaite (CaCO3·6H2O) and ice-air CO2 fluxes, are also included. The model is evaluated using observations from a 6 month field study at Point Barrow, Alaska, and an ice-tank experiment. At Barrow, results show that the DIC budget is mainly driven by physical processes, wheras brine-air CO2 fluxes, ikaite formation, and net primary production, are secondary factors. In terms of ice-atmosphere CO2 exchanges, sea ice is a net CO2 source and sink in winter and summer, respectively. The formulation of the ice-atmosphere CO2 flux impacts the simulated near-surface CO2 partial pressure (pCO2), but not the DIC budget. Because the simulated ice-atmosphere CO2 fluxes are limited by DIC stocks, and therefore <2 mmol m-2 d-1, we argue that the observed much larger CO2 fluxes from eddy covariance retrievals cannot be explained by a sea ice direct source and must involve other processes or other sources of CO2. Finally, the simulations suggest that near-surface TA/DIC ratios of ˜2, sometimes used as an indicator of calcification, would rather suggest outgassing.

  10. Drivers of inorganic carbon dynamics in first-year sea ice: A model study

    NASA Astrophysics Data System (ADS)

    Moreau, Sébastien; Vancoppenolle, Martin; Delille, Bruno; Tison, Jean-Louis; Zhou, Jiayun; Kotovich, Marie; Thomas, David; Geilfus, Nicolas-Xavier; Goosse, Hugues

    2015-04-01

    Sea ice is an active source or a sink for carbon dioxide (CO2), although to what extent is not clear. Here, we analyze CO2 dynamics within sea ice using a one-dimensional halo-thermodynamic sea ice model including gas physics and carbon biogeochemistry. The ice-ocean fluxes, and vertical transport, of total dissolved inorganic carbon (DIC) and total alkalinity (TA) are represented using fluid transport equations. Carbonate chemistry, the consumption and release of CO2 by primary production and respiration, the precipitation and dissolution of ikaite (CaCO3•6H2O) and ice-air CO2 fluxes, are also included. The model is evaluated using observations from a 6-month field study at Point Barrow, Alaska and an ice-tank experiment. At Barrow, results show that the DIC budget is mainly driven by physical processes, wheras brine-air CO2 fluxes, ikaite formation, and net primary production, are secondary factors. In terms of ice-atmosphere CO2 exchanges, sea ice is a net CO2 source and sink in winter and summer, respectively. The formulation of the ice-atmosphere CO2 flux impacts the simulated near-surface CO2 partial pressure (pCO2), but not the DIC budget. Because the simulated ice-atmosphere CO2 fluxes are limited by DIC stocks, and therefore < 2 mmol m-2 day-1, we argue that the observed much larger CO2 fluxes from eddy covariance retrievals cannot be explained by a sea ice direct source and must involve other processes or other sources of CO2. Finally, the simulations suggest that near surface TA/DIC ratios of ~2, sometimes used as an indicator of calcification, would rather suggest outgassing.

  11. Inorganic membranes for carbon capture and power generation

    NASA Astrophysics Data System (ADS)

    Snider, Matthew T.

    Inorganic membranes are under consideration for cost-effective reductions of carbon emissions from coal-fired power plants, both in the capture of pollutants post-firing and in the direct electrochemical conversion of coal-derived fuels for improved plant efficiency. The suitability of inorganic membrane materials for these purposes stems as much from thermal and chemical stability in coal plant operating conditions as from high performance in gas separations and power generation. Hydrophilic, micro-porous zeolite membrane structures are attractive for separating CO2 from N2 in gaseous waste streams due to the attraction of CO2 to the membrane surface and micropore walls that gives the advantage to CO2 transport. Recent studies have indicated that retention of the templating agent used in zeolite synthesis can further block N2 from the micropore interior and significantly improve CO2/N2 selectivity. However, the role of the templating agent in micro-porous transport has not been well investigated. In this work, gas sorption studies were conducted by high-pressure thermo-gravimetric analysis on Zeolite Y membrane materials to quantify the effect of the templating agent on CO2, N2, and H2O adsorption/desorption, as well as to examine the effect of humidification on overall membrane performance. In equilibrium conditions, the N2 sorption enthalpy was nearly unchanged by the presence of the templating agent, but the N2 pore occupation was reduced ˜1000x. Thus, the steric nature of the blocking of N2 from the micropores by the templating agent was confirmed. CO2 and H2O sorption enthalpies were similarly unaffected by the templating agent, and the micropore occupations were only reduced as much as the void volume taken up by the templating agent. Thus, the steric blocking effect did not occur for molecules more strongly attracted to the micropore walls. Additionally, in time-transient measurements the CO 2 and H2O mobilities were significantly enhanced by the presence

  12. Method for producing heat-resistant semi-inorganic compounds

    NASA Technical Reports Server (NTRS)

    Yajima, S.; Okamura, K.; Shishido, T.; Hasegawa, Y.

    1983-01-01

    The method for producing a heat resistant, semi-inorganic compound is discussed. Five examples in which various alcohols, phenols, and aromatic carbonic acids are used to test heat resistance and solubility are provided.

  13. Cellular uptake mechanisms of functionalised multi-walled carbon nanotubes by 3D electron tomography imaging

    NASA Astrophysics Data System (ADS)

    Al-Jamal, Khuloud T.; Nerl, Hannah; Müller, Karin H.; Ali-Boucetta, Hanene; Li, Shouping; Haynes, Peter D.; Jinschek, Joerg R.; Prato, Maurizio; Bianco, Alberto; Kostarelos, Kostas; Porter, Alexandra E.

    2011-06-01

    Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed that MWNT-NH3+ were internalised in both phagocytic and non-phagocytic cells by any one of three mechanisms: (a) individually via membrane wrapping; (b) individually by direct membrane translocation; and (c) in clusters within vesicular compartments. At early time points following intracellular translocation, we noticed accumulation of nanotube material within various intracellular compartments, while a long-term (14-day) study using primary human macrophages revealed that MWNT-NH3+ were able to escape vesicular (phagosome) entrapment by translocating directly into the cytoplasm.Carbon nanotubes (CNTs) are being investigated for a variety of biomedical applications. Despite numerous studies, the pathways by which carbon nanotubes enter cells and their subsequent intracellular trafficking and distribution remain poorly determined. Here, we use 3-D electron tomography techniques that offer optimum enhancement of contrast between carbon nanotubes and the plasma membrane to investigate the mechanisms involved in the cellular uptake of shortened, functionalised multi-walled carbon nanotubes (MWNT-NH3+). Both human lung epithelial (A549) cells, that are almost incapable of phagocytosis and primary macrophages, capable of extremely efficient phagocytosis, were used. We observed

  14. Amino acid uptake by temperate tree species characteristic of low- and high-fertility habitats.

    PubMed

    Scott, Emily E; Rothstein, David E

    2011-10-01

    The relationship between inorganic nitrogen (N) cycling and plant productivity is well established. However, recent research has demonstrated the ability of plants to take up low molecular weight organic N compounds (i.e., amino acids) at rates that often rival those of inorganic N forms. In this study, we hypothesize that temperate forest tree species characteristic of low-fertility habitats will prefer amino acids over species characteristic of high-fertility habitats. We measured the uptake of (15)N-labeled amino acids (glycine, glutamine, arginine, serine), ammonium (NH(4)(+)), and nitrate (NO(3)(-)) by four tree species that commonly occur in eastern North America, where their abundances have been correlated with inorganic N availability. Specific uptake rates of amino acids were largely similar for all tree species; however, high-fertility species took up NH(4)(+) at rates more than double those of low-fertility species, rendering amino acid N relatively more important to the N nutrition of low-fertility species. Low-fertility species acquired over four times more total N from arginine compared to NH(4)(+) and NO(3)(-); high-fertility species acquired the most N from NH(4)(+). Arginine had the highest uptake rates of any amino acid by all species; there were no significant differences in uptake rates of the remaining amino acids. Our results support the idea that the dominant species in a particular habitat are those best able to utilize the most available N resources.

  15. [Spatial-temporal distributions of dissolved inorganic carbon and its affecting factors in the Yellow River estuary].

    PubMed

    Guo, Xing-Sen; Lü, Ying-Chun; Sun, Zhi-Gao; Wang, Chuan-Yuan; Zhao, Quan-Sheng

    2015-02-01

    Estuary is an important area contributing to the global carbon cycle. In order to analyze the spatial-temporal distribution characteristics of the dissolved inorganic carbon (DIC) in the surface water of Yellow River estuary. Samples were collected in spring, summer, fall, winter of 2013, and discussed the correlation between the content of DIC and environmental factors. The results show that, the DIC concentration of the surface water in Yellow River estuary is in a range of 26.34-39.43 mg x L(-1), and the DIC concentration in freshwater side is higher than that in the sea side. In some areas where the salinity is less than 15 per thousand, the DIC concentration appears significant losses-the maximum loss is 20.46%. Seasonal distribution of performance in descending order is spring, fall, winter, summer. Through principal component analysis, it shows that water temperature, suspended solids, salinity and chlorophyll a are the main factors affecting the variation of the DIC concentration in surface water, their contribution rate is as high as 83% , and alkalinity, pH, dissolved organic carbon, dissolved oxygen and other factors can not be ignored. The loss of DIC in the low area is due to the calcium carbonate sedimentation. DIC presents a gradually increasing trend, which is mainly due to the effects of water retention time, temperature, outside input and environmental conditions.

  16. Inorganic phosphorus fertilizer ameliorates maize growth by reducing metal uptake, improving soil enzyme activity and microbial community structure.

    PubMed

    Wu, Wencheng; Wu, Jiahui; Liu, Xiaowen; Chen, Xianbin; Wu, Yingxin; Yu, Shixiao

    2017-09-01

    Recently, several studies have showed that both organic and inorganic fertilizers are effective in immobilizing heavy metals at low cost, in comparison to other remediation strategies for heavy metal-contaminated farmlands. A pot trial was conducted in this study to examine the effects of inorganic P fertilizer and organic fertilizer, in single application or in combination, on growth of maize, heavy metal availabilities, enzyme activities, and microbial community structure in metal-contaminated soils from an electronic waste recycling region. Results showed that biomass of maize shoot and root from the inorganic P fertilizer treatments were respectively 17.8 and 10.0 folds higher than the un-amended treatments (CK), while the biomass in the organic fertilizer treatments was only comparable to the CK. In addition, there were decreases of 85.0% in Cd, 74.3% in Pb, 66.3% in Cu, and 91.9% in Zn concentrations in the roots of maize grown in inorganic P fertilizer amended soil. Consistently, urease and catalase activities in the inorganic P fertilizer amended soil were 3.3 and 2.0 times higher than the CK, whereas no enhancement was observed in the organic fertilizer amended soil. Moreover, microbial community structure was improved by the application of inorganic P fertilizer, but not by organic fertilizer; the beneficial microbial groups such as Kaistobacter and Koribacter were most frequently detected in the inorganic P fertilizer amended soil. The negligible effect from the organic fertilizer might be ascribed to the decreased pH value in soils. The results suggest that the application of inorganic P fertilizer (or in combination with organic fertilizer) might be a promising strategy for the remediation of heavy metals contaminated soils in electronic waste recycling region. Copyright © 2017. Published by Elsevier Inc.

  17. Strategies of dissolved inorganic carbon use in macroalgae across a gradient of terrestrial influence: implications for the Great Barrier Reef in the context of ocean acidification

    NASA Astrophysics Data System (ADS)

    Diaz-Pulido, Guillermo; Cornwall, Christopher; Gartrell, Patrick; Hurd, Catriona; Tran, Dien V.

    2016-12-01

    Macroalgae are generally used as indicators of coral reef status; thus, understanding the drivers and mechanisms leading to increased macroalgal abundance are of critical importance. Ocean acidification (OA) due to elevated carbon dioxide (CO2) concentrations has been suggested to stimulate macroalgal growth and abundance on reefs. However, little is known about the physiological mechanisms by which reef macroalgae use CO2 from the bulk seawater for photosynthesis [i.e., (1) direct uptake of bicarbonate (HCO3 -) and/or CO2 by means of carbon concentrating mechanisms (CCM) and (2) the diffusive uptake of CO2], which species could benefit from increased CO2 or which habitats may be more susceptible to acidification-induced algal proliferations. Here, we provide the first quantitative examination of CO2-use strategies in coral reef macroalgae and provide information on how the proportion of species and the proportional abundance of species utilising each of the carbon acquisition strategies varies across a gradient of terrestrial influence (from inshore to offshore reefs) in the Great Barrier Reef (GBR). Four macroalgal groups were identified based on their carbon uptake strategies: (1) CCM-only (HCO3 - only users); (2) CCM-HCO3 -/CO2 (active uptake HCO3 - and/or CO2 use); (3) Non-CCM species (those relying on diffusive CO2 uptake); and (4) Calcifiers. δ13C values of macroalgae, confirmed by pH drift assays, show that diffusive CO2 use is more prevalent in deeper waters, possibly due to low light availability that limits activity of CCMs. Inshore shallow reefs had a higher proportion of CCM-only species, while reefs further away from terrestrial influence and exposed to better water quality had a higher number of non-CCM species than inshore and mid-shelf reefs. As non-CCM macroalgae are more responsive to increased seawater CO2 and OA, reef slopes of the outer reefs are probably the habitats most vulnerable to the impacts of OA. Our results suggest a potentially

  18. A Comparison of Recent Organic and Inorganic Carbon Isotope Records: Why Do They Covary in Some Settings and Not In Others?

    NASA Astrophysics Data System (ADS)

    Oehlert, A. M.; Swart, P. K.

    2013-12-01

    Covariance between inorganic and organic δ13C records has been used to determine whether a deposit has been altered by diagenesis, how the dynamics of the global carbon cycle changed during the production of the sediments in the deposit, and also for chronostratigraphic correlations. Although covariant records are observed in the ancient geologic record in a variety of depositional environments, such comparisons are not widely applied to modern deposits where definitive data regarding sediment producers, sea level fluctuations, and changes in the global carbon cycle are available. This study uses paired δ13C records from cores collected by the Ocean Drilling Program from three modern periplatform settings (the Great Bahama Bank, the Great Australian Bight, and the Great Barrier Reef), and two pelagic settings (the Walvis Ridge, and the Madingley Rise). These sites were selected in order to assess the influence of several different environmental factors including; sediment and organic matter producers, sediment mineralogy, margin architecture, sea level oscillations, and sediment transport pathways. In the three periplatform settings, multiple cores arranged in a margin to basin transect were analyzed in order to provide insights into the effects of downslope sediment transport. The preliminary results of this study suggest that sea level oscillations and margin architecture may artificially generate a covarying relationship in periplatform sediments that is unrelated to changes in the global carbon cycle. Furthermore, preliminary results from the Walvis Ridge and the Madingley Rise sediments suggest that the relationship between inorganic and organic δ13C records may not always exhibit a positive covariance as is currently assumed for pelagic carbonates.

  19. Effect of dispersants of multi-walled carbon nanotubes on cellular uptake and biological responses

    PubMed Central

    Haniu, Hisao; Saito, Naoto; Matsuda, Yoshikazu; Kim, Yoong-Ahm; Park, Ki Chul; Tsukahara, Tamotsu; Usui, Yuki; Aoki, Kaoru; Shimizu, Masayuki; Ogihara, Nobuhide; Hara, Kazuo; Takanashi, Seiji; Okamoto, Masanori; Ishigaki, Norio; Nakamura, Koichi; Kato, Hiroyuki

    2011-01-01

    Although there have been many reports about the cytotoxicity of multi-walled carbon nanotubes (MWCNTs), the results are still controversial. To investigate one possible reason, the authors investigated the influence of MWCNT dispersants on cellular uptake and cytotoxicity. Cytotoxicity was examined (measured by alamarBlue® assay), as well as intracellular MWCNT concentration and cytokine secretion (measured by flow cytometry) in human bronchial epithelial cells (BEAS-2B) exposed to a type of highly purified MWCNT vapor grown carbon fiber (VGCF®, Shōwa Denkō Kabushiki-gaisha, Tokyo, Japan) in three different dispersants (gelatin, carboxylmethyl cellulose, and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine). The authors also researched the relationship between the intracellular concentration of MWCNTs and cytotoxicity by using two cell lines, BEAS-2B and MESO-1 human malignant pleural mesothelioma cells. The intracellular concentration of VGCF was different for each of the three dispersants, and the levels of cytotoxicity and inflammatory response were correlated with the intracellular concentration of VGCF. A relationship between the intracellular concentration of VGCF and cytotoxic effects was observed in both cell lines. The results indicate that dispersants affect VGCF uptake into cells and that cytotoxicity depends on the intracellular concentration of VGCF, not on the exposed dosage. Thus, toxicity appears to depend on exposure time, even at low VGCF concentrations, because VGCF is biopersistent. PMID:22228997

  20. The effect of dimensionality of nanostructured carbon on the architecture of organic-inorganic hybrid materials.

    PubMed

    Misra, R D K; Depan, D; Shah, J

    2013-08-21

    The natural tendency of carbon nanotubes (CNTs) to agglomerate is an underlying reason that prevents the realization of their full potential. On the other hand, covalent functionalization of CNTs to control dispersion leads to disruption of π-conjugation in CNTs and the non-covalent functionalization leads to a weak CNT-polymer interface. To overcome these challenges, we describe the characteristics of fostering of direct nucleation of polymers on nanostructured carbon (CNTs of diameters (~2-200 nm), carbon nanofibers (~200-300 nm), and graphene), which culminates in interfacial adhesion, resulting from electrostatic and van der Waals interaction in the hybrid nanostructured carbon-polymer architecture. Furthermore, the structure is tunable through a change in undercooling. High density polyethylene and polypropylene were selected as two model polymers and two sets of experiments were carried out. The first set of experiments was carried out using CNTs of diameter ~2-5 nm to explore the effect of undercooling and polymer concentration. The second set of experiments was focused on studying the effect of dimensionality on geometrical confinements. The periodic crystallization of polyethylene on small diameter CNTs is demonstrated to be a consequence of the geometrical confinement effect, rather than epitaxy, such that petal-like disks nucleate on large diameter CNTs, carbon nanofibers, and graphene. The application of the process is illustrated in terms of fabricating a system for cellular uptake and bioimaging.

  1. Heterotrophic bacterioplankton control on organic and inorganic carbon cycle in stratified and non-stratified lakes of NW Russia

    NASA Astrophysics Data System (ADS)

    Shirokova, Liudmila; Vorobjeva, Taissia; Zabelina, Svetlana; Moreva, Olga; Klimov, Sergey; Shorina, Natalja; Chupakov, Artem; Pokrovsky, Oleg; Audry, Stephan; Viers, Jerome

    2010-05-01

    Lakes of boreal zone regulate the fate of dissolved carbon, nutrients and trace metals during their transport from the watershed to the ocean. Study of primary production - mineralization processes in the context of carbon biogeochemical cycle allows determination of the rate and mechanisms of phytoplankton biomass production and its degradation via aquatic heterotrophic bacteria. In particular, comparative study of vertical distribution of Dissolved Organic Carbon (DOC) in stratified and non-stratified lakes allows establishing the link between biological and chemical aspects of the carbon cycle which, in turns, determines an environmental stability and recovering potential of the entire ecosystem. In order to better understand the biogeochemical mechanisms that control dissolved organic and inorganic carbon migration in surface boreal waters, we studied in 2007-2009 two strongly stratified lakes (15-20 m deep) and two shallow lakes (2-4 m deep) in the Arkhangelsk region (NW Russia, White Sea basin). We conducted natural experiments of the lake water incubation for measurements of the intensity of production/mineralization processes and we determined vertical concentration of DOC during four basic hydrological seasons (winter and summer stratification, and spring and autumn lake overturn). Our seasonal studies of production/mineralization processes demonstrated high intensity of organic matter formation during summer period and significant retard of these processes during winter stagnation. During spring period, there is a strong increase of bacterial destruction of the allochtonous organic matter that is being delivered to the lake via terrigenous input. During autumn overturn, there is a decrease of the activity of phytoplankton, and the degradation of dead biomass by active bacterial community. Organic matter destruction processes are the most active in Svyatoe lake, whereas in the Beloe lake, the rate of organic matter production is significantly higher than

  2. Inorganic rechargeable non-aqueous cell

    DOEpatents

    Bowden, William L.; Dey, Arabinda N.

    1985-05-07

    A totally inorganic non-aqueous rechargeable cell having an alkali or alkaline earth metal anode such as of lithium, a sulfur dioxide containing electrolyte and a discharging metal halide cathode, such as of CuCl.sub.2, CuBr.sub.2 and the like with said metal halide being substantially totally insoluble in SO.sub.2 and admixed with a conductive carbon material.

  3. Hybrid organic-inorganic rotaxanes and molecular shuttles.

    PubMed

    Lee, Chin-Fa; Leigh, David A; Pritchard, Robin G; Schultz, David; Teat, Simon J; Timco, Grigore A; Winpenny, Richard E P

    2009-03-19

    The tetravalency of carbon and its ability to form covalent bonds with itself and other elements enables large organic molecules with complex structures, functions and dynamics to be constructed. The varied electronic configurations and bonding patterns of inorganic elements, on the other hand, can impart diverse electronic, magnetic, catalytic and other useful properties to molecular-level structures. Some hybrid organic-inorganic materials that combine features of both chemistries have been developed, most notably metal-organic frameworks, dense and extended organic-inorganic frameworks and coordination polymers. Metal ions have also been incorporated into molecules that contain interlocked subunits, such as rotaxanes and catenanes, and structures in which many inorganic clusters encircle polymer chains have been described. Here we report the synthesis of a series of discrete rotaxane molecules in which inorganic and organic structural units are linked together mechanically at the molecular level. Structural units (dialkyammonium groups) in dumb-bell-shaped organic molecules template the assembly of essentially inorganic 'rings' about 'axles' to form rotaxanes consisting of various numbers of rings and axles. One of the rotaxanes behaves as a 'molecular shuttle': the ring moves between two binding sites on the axle in a large-amplitude motion typical of some synthetic molecular machine systems. The architecture of the rotaxanes ensures that the electronic, magnetic and paramagnetic characteristics of the inorganic rings-properties that could make them suitable as qubits for quantum computers-can influence, and potentially be influenced by, the organic portion of the molecule.

  4. Inorganic versus organic selenium supplementation: a review.

    PubMed

    Mahima; Verma, Amit Kumar; Kumar, Amit; Rahal, Anu; Kumar, Vinod; Roy, Debashis

    2012-05-01

    Selenium is an essential trace element in the diets which is required for maintenance of health, growth and biochemical-physiological functions. The area covered in this review has been rapidly unfolding in recent years and has already acquired a vast spread. This study presents a concise introductory overview of the effect of organic and inorganic selenium on growth performance, carcass traits, daily egg production, egg quality, Se uptake in various tissues and plasma and plasma glutathione peroxidase activity in animals.

  5. 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. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  6. Multiwalled carbon nanotubes enter broccoli cells enhancing growth and water uptake of plants exposed to salinity.

    PubMed

    Martínez-Ballesta, M Carmen; Zapata, Lavinia; Chalbi, Najla; Carvajal, Micaela

    2016-06-08

    Carbon nanotubes have been shown to improve the germination and growth of some plant species, extending the applicability of the emerging nano-biotechnology field to crop science. In this work, exploitation of commercial multiwalled carbon nanotubes (MWCNTs) in control and 100 mM NaCl-treated broccoli was performed. Transmission electron microscopy demonstrated that MWCNTs can enter the cells in adult plants with higher accumulation under salt stress. Positive effect of MWCNTs on growth in NaCl-treated plants was consequence of increased water uptake, promoted by more-favourable energetic forces driving this process, and enhanced net assimilation of CO2. MWCNTs induced changes in the lipid composition, rigidity and permeability of the root plasma membranes relative to salt-stressed plants. Also, enhanced aquaporin transduction occurred, which improved water uptake and transport, alleviating the negative effects of salt stress. Our work provides new evidences about the effect of MWCNTs on plasma membrane properties of the plant cell. The positive response to MWCNTs in broccoli plants opens novel perspectives for their technological uses in new agricultural practices, especially when 1plants are exposed to saline environments.

  7. Inorganic/organic doped carbon aerogels as biosensing materials for the detection of hydrogen peroxide.

    PubMed

    Dong, Sheying; Li, Nan; Suo, Gaochao; Huang, Tinglin

    2013-12-17

    In this article, three different inorganic/organic doped carbon aerogel (CA) materials (Ni-CA, Pd-CA, and Ppy-CA) were, respectively, mixed with ionic liquid (IL) to form three stable composite films, which were used as enhanced elements for an integrated sensing platform to increase the surface area and to improve the electronic transmission rate. Subsequently, the effect of the materials performances such as adsorption, specific surface area and conductivity on electrochemistry for myoglobin (Mb) was discussed using N2 adsorption-desorption isotherm measurements, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Moreover, they could act as sensors toward the detection of hydrogen peroxide (H2O2) with lower detection limits (1.68 μM, 1.02 μM, and 0.85 μM, for Ni-CA/IL/Mb-CPE, Pd-CA/IL/Mb-CPE, and Ppy-CA/IL/Mb-CPE, respectively) and smaller apparent Michaelis-Menten constants KM. The results indicated that the electroconductibility of the doped CA materials would become dominant, thus playing an important role in facilitating the electron transfer. Meanwhile, the synergetic effect with [BMIm]BF4 IL improved the capability of the composite inorganic/organic doped CA/IL matrix for protein immobilization. This work demonstrates the feasibility and the potential of a series of CA-based hybrid materials as biosensors, and further research and development are required to prepare other functional CAs and make them valuable for more extensive application in biosensing.

  8. Inorganic Membranes: Preparation and Application for Water Treatment and Desalination

    PubMed Central

    McKay, Gordon; Buekenhoudt, Anita; Motmans, Filip; Khraisheh, Marwan; Atieh, Muataz

    2018-01-01

    Inorganic membrane science and technology is an attractive field of membrane separation technology, which has been dominated by polymer membranes. Recently, the inorganic membrane has been undergoing rapid development and innovation. Inorganic membranes have the advantage of resisting harsh chemical cleaning, high temperature and wear resistance, high chemical stability, long lifetime, and autoclavable. All of these outstanding properties made inorganic membranes good candidates to be used for water treatment and desalination applications. This paper is a state of the art review on the synthesis, development, and application of different inorganic membranes for water and wastewater treatment. The inorganic membranes reviewed in this paper include liquid membranes, dynamic membranes, various ceramic membranes, carbon based membranes, silica membranes, and zeolite membranes. A brief description of the different synthesis routes for the development of inorganic membranes for application in water industry is given and each synthesis rout is critically reviewed and compared. Thereafter, the recent studies on different application of inorganic membrane and their properties for water treatment and desalination in literature are critically summarized. It was reported that inorganic membranes despite their high synthesis cost, showed very promising results with high flux, full salt rejection, and very low or no fouling. PMID:29304024

  9. Photochemical Mineralization of Terrigenous DOC to Dissolved Inorganic Carbon in Ocean

    NASA Astrophysics Data System (ADS)

    Aarnos, Hanna; Gélinas, Yves; Kasurinen, Ville; Gu, Yufei; Puupponen, Veli-Mikko; Vähätalo, Anssi V.

    2018-02-01

    When terrigenous dissolved organic carbon (tDOC) rich in chromophoric dissolved organic matter (tCDOM) enters the ocean, solar radiation mineralizes it partially into dissolved inorganic carbon (DIC). This study addresses the amount and the rates of DIC photoproduction from tDOC and the area of ocean required to photomineralize tDOC. We collected water samples from 10 major rivers, mixed them with artificial seawater, and irradiated them with simulated solar radiation to measure DIC photoproduction and the photobleaching of tCDOM. The linear relationship between DIC photoproduction and tCDOM photobleaching was used to estimate the amount of photoproduced DIC from the tCDOM fluxes of the study rivers. Solar radiation was estimated to mineralize 12.5 ± 3.7 Tg C yr-1 (10 rivers)-1 or 18 ± 8% of tDOC flux. The irradiation experiments also approximated typical apparent spectral quantum yields for DIC photoproduction (ϕλ) over the entire lifetime of the tCDOM. Based on ϕλs and the local solar irradiances in river plumes, the annual areal DIC photoproduction rates from tDOC were calculated to range from 52 ± 4 (Lena River) to 157 ± 2 mmol C m-2 yr-1 (Mississippi River). When the amount of photoproduced DIC was divided by the areal rate, 9.6 ± 2.5 × 106 km2 of ocean was required for the photomineralization of tDOC from the study rivers. Extrapolation to the global tDOC flux yields 45 (31-58) Tg of photoproduced DIC per year in the river plumes that cover 34 (25-43) × 106 km2 of the ocean.

  10. Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?

    NASA Astrophysics Data System (ADS)

    Levas, Stephen; Grottoli, Andréa G.; Schoepf, Verena; Aschaffenburg, Matthew; Baumann, Justin; Bauer, James E.; Warner, Mark E.

    2016-06-01

    Annual coral bleaching events due to increasing sea surface temperatures are predicted to occur globally by the mid-century and as early as 2025 in the Caribbean, and severely impact coral reefs. We hypothesize that heterotrophic carbon (C) in the form of zooplankton and dissolved organic carbon (DOC) is a significant source of C to bleached corals. Thus, the ability to utilize multiple pools of fixed carbon and/or increase the amount of fixed carbon acquired from one or more pools of fixed carbon (defined here as heterotrophic plasticity) could underlie coral acclimatization and persistence under future ocean-warming scenarios. Here, three species of Caribbean coral— Porites divaricata, P. astreoides, and Orbicella faveolata—were experimentally bleached for 2.5 weeks in two successive years and allowed to recover in the field. Zooplankton feeding was assessed after single and repeat bleaching, while DOC fluxes and the contribution of DOC to the total C budget were determined after single bleaching, 11 months on the reef, and repeat bleaching. Zooplankton was a large C source for P. astreoides, but only following single bleaching. DOC was a source of C for single-bleached corals and accounted for 11-36 % of daily metabolic demand (CHARDOC), but represented a net loss of C in repeat-bleached corals. In repeat-bleached corals, DOC loss exacerbated the negative C budgets in all three species. Thus, the capacity for heterotrophic plasticity in corals is compromised under annual bleaching, and heterotrophic uptake of DOC and zooplankton does not mitigate C budget deficits in annually bleached corals. Overall, these findings suggest that some Caribbean corals may be more susceptible to repeat bleaching than to single bleaching due to a lack of heterotrophic plasticity, and coral persistence under increasing bleaching frequency may ultimately depend on other factors such as energy reserves and symbiont shuffling.

  11. Fermentation process for the production of organic acids

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hermann, Theron; Reinhardt, James; Yu, Xiaohui

    This invention relates to improvements in the fermentation process used in the production of organic acids from biological feedstock using bacterial catalysts. The improvements in the fermentation process involve providing a fermentation medium comprising an appropriate form of inorganic carbon, an appropriate amount of aeration and a biocatalyst with an enhanced ability to uptake and assimilate the inorganic carbon into the organic acids. This invention also provides, as a part of an integrated fermentation facility, a novel process for producing a solid source of inorganic carbon by sequestering carbon released from the fermentation in an alkali solution.

  12. Pore-Water Carbonate and Phosphate As Predictors of Arsenate Toxicity in Soil.

    PubMed

    Lamb, Dane T; Kader, Mohammed; Wang, Liang; Choppala, Girish; Rahman, Mohammad Mahmudur; Megharaj, Mallavarapu; Naidu, Ravi

    2016-12-06

    Phytotoxicity of inorganic contaminants is influenced by the presence of competing ions at the site of uptake. In this study, interaction of soil pore-water constituents with arsenate toxicity was investigated in cucumber (Cucumis sativa L) using 10 contrasting soils. Arsenate phytotoxicity was shown to be related to soluble carbonate and phosphate. The data indicated that dissolved phosphate and carbonate had an antagonistic impact on arsenate toxicity to cucumber. To predict arsenate phytotoxicity in soils with a diverse range of soil solution properties, both carbonate and phosphate were required. The relationship between arsenic and pore-water toxicity parameters was established initially using multiple regression. In addition, based on the relationship with carbonate and phosphate we successively applied a terrestrial biotic ligand-like model (BLM) including carbonate and phosphate. Estimated effective concentrations from the BLM-like parametrization were strongly correlated to measured arsenate values in pore-water (R 2 = 0.76, P < 0.001). The data indicates that an ion interaction model similar to the BLM for arsenate is possible, potentially improving current risk assessments at arsenic and co-contaminated soils.

  13. Determination of the δ13C of dissolved inorganic carbon in water; RSIL lab code 1710

    USGS Publications Warehouse

    Singleton, Glenda L.; Revesz, Kinga; Coplen, Tyler B.

    2012-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1710 is to present a method to determine the δ13C of dissolved inorganic carbon (DIC) of water. The DIC of water is precipitated using ammoniacal strontium chloride (SrCl2) solution to form strontium carbonate (SrCO3). The δ13C is analyzed by reacting SrCO3 with 100-percent phosphoric acid (H3PO4) to liberate carbon quantitatively as carbon dioxide (CO2), which is collected, purified by vacuum sublimation, and analyzed by dual inlet isotope-ratio mass spectrometry (DI-IRMS). The DI-IRMS is a DuPont double-focusing mass spectrometer. One ion beam passes through a slit in a forward collector and is collected in the rear collector. The other measurable ion beams are collected in the front collector. By changing the ion-accelerating voltage under computer control, the instrument is capable of measuring mass/charge (m/z) 45 or 46 in the rear collector and m/z 44 and 46 or 44 and 45, respectively, in the front collector. The ion beams from these m/z values are as follows: m/z 44 = CO2 = 12C16O16O, m/z 45 = CO2 = 13C16O16O primarily, and m/z 46 = CO2 = 12C16O18O primarily. The data acquisition and control software calculates δ13C values.

  14. Intrinsic activation: the relationship between biomass inorganic content and porosity formation during pyrolysis.

    PubMed

    Stratford, James P; Hutchings, Tony R; de Leij, Frans A A M

    2014-05-01

    The utility of pyrolytic carbons is closely related to their porosity and surface area, there is a clear benefit to the development of biomass pyrolysis processes which produce highly porous carbons. The results presented in this work demonstrate that by using biomass precursors with high inorganic content along with specified process conditions, carbons can be consistently produced with specific surface areas between 900 and 1600 m(2)/g. Results from 12 different source materials show that the formation of increased porosity in pyrolytic carbons is strongly associated with the presence of inorganic elements in the precursors including: magnesium, potassium and sulfur. It was found that pyrolysis of macro-algae can produce especially high specific surface area carbons (mean: 1500 m(2)/g), without externally applied activating agents. Using cheap readily available agricultural residues such as oilseed rape straw, pyrolytic carbons can be produced with specific surface areas of around 950 m(2)/g. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. The relationship between the dissolved inorganic carbon concentration and growth rate in marine phytoplankton.

    PubMed Central

    Clark, D R; Flynn, K J

    2000-01-01

    A range of marine phytoplankton was grown in closed systems in order to investigate the kinetics of dissolved inorganic carbon (DIC) use and the influence of the nitrogen source under conditions of constant pH. The kinetics of DIC use could be described by a rectangular hyperbolic curve, yielding estimations of KG(DIC) (the half saturation constant for carbon-specific growth, i.e. C mu) and mu max (the theoretical maximum C mu). All species attained a KG(DIC) within the range of 30-750 microM DIC. For most species, NH4+ use enabled growth with a lower KG(DIC) and/or, for two species, an increase in mu max. At DIC concentrations of > 1.6 mM, C mu was > 90% saturated for all species relative to the rate at the natural seawater DIC concentration of 2.0 mM. The results suggest that neither the rate nor the extent of primary productivity will be significantly limited by the DIC in the quasi-steady-state conditions associated with oligotrophic oceans. The method needs to be applied in the conditions associated with dynamic coastal (eutrophic) systems for clarification of a potential DIC rate limitation where cells may grow to higher densities and under variable pH and nitrogen supply. PMID:10874743

  16. Variation of photoautotrophic fatty acid production from a highly CO2 tolerant alga, Chlorococcum littorale, with inorganic carbon over narrow ranges of pH.

    PubMed

    Ota, Masaki; Takenaka, Motohiro; Sato, Yoshiyuki; Smith, Richard L; Inomata, Hiroshi

    2015-01-01

    Photoautotrophic fatty acid production of a highly CO2 -tolerant green alga Chlorococcum littorale in the presence of inorganic carbon at 295 K and light intensity of 170 µmol-photon m(-2) s(-1) was investigated. CO2 concentration in the bubbling gas was adjusted by mixing pure gas components of CO2 and N2 to avoid photorespiration and β-oxidation of fatty acids under O2 surrounding conditions. Maximum content of total fatty acid showed pH-dependence after nitrate depletion of the culture media and increased with the corresponding inorganic carbon ratio. Namely, [HCO3 (-) ]/([CO2 ]+n[ CO32-]) ratio in the culture media was found to be a controlling factor for photoautotrophic fatty acid production after the nitrate limitation. At a CO2 concentration of 5% (vol/vol) and a pH of 6.7, the fatty acid content was 47.8 wt % (dry basis) at its maximum that is comparable with land plant seed oils. © 2015 American Institute of Chemical Engineers.

  17. Seasonal carbon uptake rates of phytoplankton in the northern East/Japan Sea

    NASA Astrophysics Data System (ADS)

    Lee, Sang Heon; Joo, HuiTae; Lee, Jae Hyung; Lee, Jang Han; Kang, Jae Joong; Lee, Ho Won; Lee, Dabin; Kang, Chang Keun

    2017-09-01

    Korea-Russia joint expeditions have been conducted mainly in the less studied Russian sector of the East/Japan Sea to understand the physical and ecological structures. In this study, the carbon uptake rates of phytoplankton measured in 2012 (middle-late October) and 2015 (middle April-early May) were analyzed to understand seasonal and spatial distributions of phytoplankton production, using a 13C-15N dual isotope tracer technique. The water columns in the euphotic layers were well mixed during our cruise periods in both years. The water column-integrated chl-a concentrations (mean ± S.D. = 2.28 ± 1.47 mg m-3) in 2015 was significantly higher (t-test, p < 0.01) than in 2012 (mean ± S.D. = 0.49 ± 0.29 mg m-3) because of different sampling seasons. Small phytoplankton (< 2 μm) were relatively dominant in 2012, whereas different sizes of phytoplankton were evenly distributed in 2015 although a spatial distribution of large phytoplankton (> 20 μm) was observed near the Russian coast. The daily carbon uptake rates in this study were 180.5 and 441.6 mg C m-2 d-1 in 2012 and 2015, respectively which are significantly (t-test, p < 0.01) lower than the averaged values previously reported in the East/Japan Sea (863 ± 679.6 mg C m-2 d-1). The potential reasons for the lower rate in this study are discussed. The small phytoplankton contribution (47.4%) averaged from the two different cruises in this study is consistent with the result (47%) reported in temperate regions. Moreover, a significantly (t-test, p < 0.01) lower contribution of small phytoplankton in total primary production than total phytoplankton biomass in this study is consistent with the results from other regions. Lower total primary production might be expected due to increasing contribution of small phytoplankton under warmer conditions.

  18. Carbonic anhydrase 2-like in the giant clam, Tridacna squamosa: characterization, localization, response to light, and possible role in the transport of inorganic carbon from the host to its symbionts.

    PubMed

    Ip, Yuen K; Koh, Clarissa Z Y; Hiong, Kum C; Choo, Celine Y L; Boo, Mel V; Wong, Wai P; Neo, Mei L; Chew, Shit F

    2017-12-01

    The fluted giant clam, Tridacna squamosa , lives in symbiosis with zooxanthellae which reside extracellularly inside a tubular system. Zooxanthellae fix inorganic carbon (C i ) during insolation and donate photosynthate to the host. Carbonic anhydrases catalyze the interconversion of CO 2 and HCO3-, of which carbonic anhydrase 2 (CA2) is the most ubiquitous and involved in many biological processes. This study aimed to clone a CA2 homolog ( CA2-like ) from the fleshy and colorful outer mantle as well as the thin and whitish inner mantle of T. squamosa , to determine its cellular and subcellular localization, and to examine the effects of light exposure on its gene and protein expression levels. The cDNA coding sequence of CA2-like from T. squamosa comprised 789 bp, encoding 263 amino acids with an estimated molecular mass of 29.6 kDa. A phenogramic analysis of the deduced CA2-like sequence denoted an animal origin. CA2-like was not detectable in the shell-facing epithelium of the inner mantle adjacent to the extrapallial fluid. Hence, CA2-like is unlikely to participate directly in light-enhanced calcification. By contrast, the outer mantle, which contains the highest density of tertiary tubules and zooxanthellae, displayed high level of CA2-like expression, and CA2-like was localized to the tubule epithelial cells. More importantly, exposure to light induced significant increases in the protein abundance of CA2-like in the outer mantle. Hence, CA2-like could probably take part in the increased supply of inorganic carbon (C i ) from the host clam to the symbiotic zooxanthellae when the latter conduct photosynthesis to fix C i during light exposure. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  19. Integrated Analysis of Engineered Carbon Limitation in a Quadruple CO2/HCO3− Uptake Mutant of Synechocystis sp. PCC 68031[OPEN

    PubMed Central

    Orf, Isabel; Klähn, Stephan; Schwarz, Doreen; Frank, Marcus; Hess, Wolfgang R.; Hagemann, Martin; Kopka, Joachim

    2015-01-01

    Cyanobacteria have efficient carbon concentration mechanisms and suppress photorespiration in response to inorganic carbon (Ci) limitation. We studied intracellular Ci limitation in the slow-growing CO2/HCO3−-uptake mutant ΔndhD3 (for NADH dehydrogenase subunit D3)/ndhD4 (for NADH dehydrogenase subunit D4)/cmpA (for bicarbonate transport system substrate-binding protein A)/sbtA (for sodium-dependent bicarbonate transporter A): Δ4 mutant of Synechocystis sp. PCC 6803. When cultivated under high-CO2 conditions, ∆4 phenocopies wild-type metabolic and transcriptomic acclimation responses after the shift from high to low CO2 supply. The ∆4 phenocopy reveals multiple compensation mechanisms and differs from the preacclimation of the transcriptional Ci regulator mutant ∆ndhR (for ndhF3 operon transcriptional regulator). Contrary to the carboxysomeless ∆ccmM (for carbon dioxide concentrating mechanism protein M) mutant, the metabolic photorespiratory burst triggered by shifting to low CO2 is not enhanced in ∆4. However, levels of the photorespiratory intermediates 2-phosphoglycolate and glycine are increased under high CO2. The number of carboxysomes is increased in ∆4 under high-CO2 conditions and appears to be the major contributing factor for the avoidance of photorespiration under intracellular Ci limitation. The ∆4 phenocopy is associated with the deregulation of Ci control, an overreduced cellular state, and limited photooxidative stress. Our data suggest multiple layers of Ci regulation, including inversely regulated modules of antisense RNAs and cognate target messenger RNAs and specific trans-acting small RNAs, such as the posttranscriptional PHOTOSYNTHESIS REGULATORY RNA1 (PsrR1), which shows increased expression in ∆4 and is involved in repressing many photosynthesis genes at the posttranscriptional level. In conclusion, our insights extend the knowledge on the range of compensatory responses of Synechocystis sp. PCC 6803 to intracellular Ci

  20. Carbon-concentrating mechanisms in seagrasses.

    PubMed

    Larkum, Anthony William D; Davey, Peter A; Kuo, John; Ralph, Peter J; Raven, John A

    2017-06-01

    Seagrasses are unique angiosperms that carry out growth and reproduction submerged in seawater. They occur in at least three families of the Alismatales. All have chloroplasts mainly in the cells of the epidermis. Living in seawater, the supply of inorganic carbon (Ci) to the chloroplasts is diffusion limited, especially under unstirred conditions. Therefore, the supply of CO2 and bicarbonate across the diffusive boundary layer on the outer side of the epidermis is often a limiting factor. Here we discuss the evidence for mechanisms that enhance the uptake of Ci into the epidermal cells. Since bicarbonate is plentiful in seawater, a bicarbonate pump might be expected; however, the evidence for such a pump is not strongly supported. There is evidence for a carbonic anhydrase outside the outer plasmalemma. This, together with evidence for an outward proton pump, suggests the possibility that local acidification leads to enhanced concentrations of CO2 adjacent to the outer tangential epidermal walls, which enhances the uptake of CO2, and this could be followed by a carbon-concentrating mechanism (CCM) in the cytoplasm and/or chloroplasts. The lines of evidence for such an epidermal CCM are discussed, including evidence for special 'transfer cells' in some but not all seagrass leaves in the tangential inner walls of the epidermal cells. It is concluded that seagrasses have a CCM but that the case for concentration of CO2 at the site of Rubisco carboxylation is not proven. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  1. A metamorphic inorganic framework that can be switched between eight single-crystalline states

    NASA Astrophysics Data System (ADS)

    Zhan, Caihong; Cameron, Jamie M.; Gabb, David; Boyd, Thomas; Winter, Ross S.; Vilà-Nadal, Laia; Mitchell, Scott G.; Glatzel, Stefan; Breternitz, Joachim; Gregory, Duncan H.; Long, De-Liang; MacDonell, Andrew; Cronin, Leroy

    2017-02-01

    The design of highly flexible framework materials requires organic linkers, whereas inorganic materials are more robust but inflexible. Here, by using linkable inorganic rings made up of tungsten oxide (P8W48O184) building blocks, we synthesized an inorganic single crystal material that can undergo at least eight different crystal-to-crystal transformations, with gigantic crystal volume contraction and expansion changes ranging from -2,170 to +1,720 Å3 with no reduction in crystallinity. Not only does this material undergo the largest single crystal-to-single crystal volume transformation thus far reported (to the best of our knowledge), the system also shows conformational flexibility while maintaining robustness over several cycles in the reversible uptake and release of guest molecules switching the crystal between different metamorphic states. This material combines the robustness of inorganic materials with the flexibility of organic frameworks, thereby challenging the notion that flexible materials with robustness are mutually exclusive.

  2. Recombinant plant gamma carbonic anhydrase homotrimers bind inorganic carbon.

    PubMed

    Martin, Victoria; Villarreal, Fernando; Miras, Isabelle; Navaza, Alda; Haouz, Ahmed; González-Lebrero, Rodolfo M; Kaufman, Sergio B; Zabaleta, Eduardo

    2009-11-03

    Gamma carbonic anhydrases (gammaCA) are widespread in Prokaryotes. In Eukaryotes, homologous genes were found only in plant genomes. In Arabidopsis and maize, the corresponding gene products are subunits of mitochondrial Complex I. At present, only gammaCA homotrimers of Methanosarcina thermophila (CAM) show reversible carbon dioxide (CO(2)) hydration activity. In the present work, it is shown that recombinant plant gammaCA2 could form homotrimers and bind H(14)CO(3)(-). However, they are unable to catalyse the reversible hydration of CO(2). These results suggest that plant gammaCAs do not act as carbonic anhydrases but with a related activity possibly contributing to recycle CO(2) in the context of photorespiration.

  3. Proteomic and Mutant Analysis of the CO 2 Concentrating Mechanism of Hydrothermal Vent Chemolithoautotroph Thiomicrospira crunogena

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mangiapia, Mary; Brown, Terry-René W.; Chaput, Dale

    Many autotrophic microorganisms are likely to adapt to scarcity in dissolved inorganic carbon (DIC; CO 2+ HCO 3 -+ CO 3 2-) with CO 2 concentrating mechanisms (CCM) that actively transport DIC across the cell membrane to facilitate carbon fixation. Surprisingly, DIC transport has been well studied among cyanobacteria and microalgae only. The deep-sea vent gammaproteobacterial chemolithoautotrophThiomicrospira crunogenahas a low-DIC inducible CCM, though the mechanism for uptake is unclear, as homologs to cyanobacterial transporters are absent. To identify the components of this CCM, proteomes ofT. crunogenacultivated under low- and high-DIC conditions were compared. Fourteen proteins, including those comprising carboxysomes, weremore » at least 4-fold more abundant under low-DIC conditions. One of these proteins was encoded byTcr_0854; strains carrying mutated copies of this gene, as well as the adjacent Tcr_0853, required elevated DIC for growth. Strains carrying mutated copies of Tcr_0853 and Tcr_0854 overexpressed carboxysomes and had diminished ability to accumulate intracellular DIC. Based on reverse transcription (RT)-PCR, Tcr_0853 and Tcr_0854 were cotranscribed and upregulated under low-DIC conditions. The Tcr_0853 -encoded protein was predicted to have 13 transmembrane helices. Given the mutant phenotypes described above, Tcr_0853 and Tcr_0854 may encode a two-subunit DIC transporter that belongs to a previously undescribed transporter family, though it is widespread among autotrophs from multiple phyla.DIC uptake and fixation by autotrophs are the primary input of inorganic carbon into the biosphere. The mechanism for dissolved inorganic carbon uptake has been characterized only for cyanobacteria despite the importance of DIC uptake by autotrophic microorganisms from many phyla among theBacteriaandArchaea. In this work, proteins necessary for dissolved inorganic carbon utilization in the deep-sea vent chemolithoautotrophT. crunogenawere identified, and

  4. Proteomic and Mutant Analysis of the CO 2 Concentrating Mechanism of Hydrothermal Vent Chemolithoautotroph Thiomicrospira crunogena

    DOE PAGES

    Mangiapia, Mary; Brown, Terry-René W.; Chaput, Dale; ...

    2017-01-23

    Many autotrophic microorganisms are likely to adapt to scarcity in dissolved inorganic carbon (DIC; CO 2+ HCO 3 -+ CO 3 2-) with CO 2 concentrating mechanisms (CCM) that actively transport DIC across the cell membrane to facilitate carbon fixation. Surprisingly, DIC transport has been well studied among cyanobacteria and microalgae only. The deep-sea vent gammaproteobacterial chemolithoautotrophThiomicrospira crunogenahas a low-DIC inducible CCM, though the mechanism for uptake is unclear, as homologs to cyanobacterial transporters are absent. To identify the components of this CCM, proteomes ofT. crunogenacultivated under low- and high-DIC conditions were compared. Fourteen proteins, including those comprising carboxysomes, weremore » at least 4-fold more abundant under low-DIC conditions. One of these proteins was encoded byTcr_0854; strains carrying mutated copies of this gene, as well as the adjacent Tcr_0853, required elevated DIC for growth. Strains carrying mutated copies of Tcr_0853 and Tcr_0854 overexpressed carboxysomes and had diminished ability to accumulate intracellular DIC. Based on reverse transcription (RT)-PCR, Tcr_0853 and Tcr_0854 were cotranscribed and upregulated under low-DIC conditions. The Tcr_0853 -encoded protein was predicted to have 13 transmembrane helices. Given the mutant phenotypes described above, Tcr_0853 and Tcr_0854 may encode a two-subunit DIC transporter that belongs to a previously undescribed transporter family, though it is widespread among autotrophs from multiple phyla.DIC uptake and fixation by autotrophs are the primary input of inorganic carbon into the biosphere. The mechanism for dissolved inorganic carbon uptake has been characterized only for cyanobacteria despite the importance of DIC uptake by autotrophic microorganisms from many phyla among theBacteriaandArchaea. In this work, proteins necessary for dissolved inorganic carbon utilization in the deep-sea vent chemolithoautotrophT. crunogenawere identified, and

  5. Proteomic and Mutant Analysis of the CO2 Concentrating Mechanism of Hydrothermal Vent Chemolithoautotroph Thiomicrospira crunogena

    PubMed Central

    Mangiapia, Mary; Brown, Terry-René W.; Chaput, Dale; Haller, Edward; Harmer, Tara L.; Hashemy, Zahra; Keeley, Ryan; Leonard, Juliana; Mancera, Paola; Nicholson, David; Stevens, Stanley; Wanjugi, Pauline; Zabinski, Tania; Pan, Chongle

    2017-01-01

    ABSTRACT Many autotrophic microorganisms are likely to adapt to scarcity in dissolved inorganic carbon (DIC; CO2 + HCO3− + CO32−) with CO2 concentrating mechanisms (CCM) that actively transport DIC across the cell membrane to facilitate carbon fixation. Surprisingly, DIC transport has been well studied among cyanobacteria and microalgae only. The deep-sea vent gammaproteobacterial chemolithoautotroph Thiomicrospira crunogena has a low-DIC inducible CCM, though the mechanism for uptake is unclear, as homologs to cyanobacterial transporters are absent. To identify the components of this CCM, proteomes of T. crunogena cultivated under low- and high-DIC conditions were compared. Fourteen proteins, including those comprising carboxysomes, were at least 4-fold more abundant under low-DIC conditions. One of these proteins was encoded by Tcr_0854; strains carrying mutated copies of this gene, as well as the adjacent Tcr_0853, required elevated DIC for growth. Strains carrying mutated copies of Tcr_0853 and Tcr_0854 overexpressed carboxysomes and had diminished ability to accumulate intracellular DIC. Based on reverse transcription (RT)-PCR, Tcr_0853 and Tcr_0854 were cotranscribed and upregulated under low-DIC conditions. The Tcr_0853-encoded protein was predicted to have 13 transmembrane helices. Given the mutant phenotypes described above, Tcr_0853 and Tcr_0854 may encode a two-subunit DIC transporter that belongs to a previously undescribed transporter family, though it is widespread among autotrophs from multiple phyla. IMPORTANCE DIC uptake and fixation by autotrophs are the primary input of inorganic carbon into the biosphere. The mechanism for dissolved inorganic carbon uptake has been characterized only for cyanobacteria despite the importance of DIC uptake by autotrophic microorganisms from many phyla among the Bacteria and Archaea. In this work, proteins necessary for dissolved inorganic carbon utilization in the deep-sea vent chemolithoautotroph T. crunogena

  6. Nitrogen and Phosphorus Plant Uptake During Periods with no Photosynthesis Accounts for About Half of Global Annual Uptake

    NASA Astrophysics Data System (ADS)

    Riley, W. J.; Zhu, Q.; Tang, J.

    2017-12-01

    Uncertainties in current Earth System Model (ESM) predictions of terrestrial carbon-climate feedbacks over the 21st century are as large as, or larger than, any other reported natural system uncertainties. Soil Organic Matter (SOM) decomposition and photosynthesis, the dominant fluxes in this regard, are tightly linked through nutrient availability, and the recent Coupled Model Inter-comparison Project 5 (CMIP5) used for climate change assessment had no credible representations of these constraints. In response, many ESM land models (ESMLMs) have developed dynamic and coupled soil and plant nutrient cycles. Here we quantify terrestrial carbon cycle impacts from well-known observed plant nutrient uptake mechanisms ignored in most current ESMLMs. In particular, we estimate the global role of plant root nutrient competition with microbes and abiotic process at night and during the non-growing season using the ACME land model (ALMv1-ECA-CNP) that explicitly represents these dynamics. We first demonstrate that short-term nutrient uptake dynamics and competition between plants and microbes are accurately predicted by the model compared to 15N and 33P isotopic tracer measurements from more than 20 sites. We then show that global nighttime and non-growing season nitrogen and phosphorus uptake accounts for 46 and 45%, respectively, of annual uptake, with large latitudinal variation. Model experiments show that ignoring these plant uptake periods leads to large positive biases in annual N leaching (globally 58%) and N2O emissions (globally 68%). Biases these large will affect modeled carbon cycle dynamics over time, and lead to predictions of ecosystems that have overly open nutrient cycles and therefore lower capacity to sequester carbon.

  7. Chlorophyll a reconstruction from in situ measurements: 2. Marked carbon uptake decrease in the last century

    NASA Astrophysics Data System (ADS)

    Fründt, B.; Dippner, J. W.; Schulz-Bull, D. E.; Waniek, J. J.

    2015-02-01

    A chlorophyll a hindcast in the Madeira Basin from 1871 to 2008 was used to analyze the long-term variability in the oligotrophic, subtropical gyres in relation to the climate change of the last century. The deep chlorophyll maximum (DCM), as dominant pattern of the chlorophyll a field, showed a fast decrease in its strength in the 1940s. An absolute minimum was reached between 1967 and 1973 when no DCM established with a recovering to the end of the time series. Long-term variability of the DCM was related to the North Atlantic Oscillation with a time delay of 9 years. The marked decrease in the 1940s was correlated to the drop of the solar radiation in transition from early brightening to global dimming. Caused by the influence of the solar radiation and maybe related to increasing global temperatures in the last century, the integrated chlorophyll a concentration decreased by about 0.7 mg m-2 in 2008 compared to 1871. The high-resolved chlorophyll a hindcast allowed an estimation of the carbon uptake by the ocean due to primary production in the euphotic zone. A rough calculation over the area of the global subtropical oceans showed 700 megaton less carbon uptake in 2008.

  8. In-situ Measured Carbon and Nitrogen Uptake Rates of Melt Pond Algae in the Western Arctic Ocean, 2014

    NASA Astrophysics Data System (ADS)

    Song, Ho Jung; Kim, Kwanwoo; Lee, Jae Hyung; Ahn, So Hyun; Joo, Houng-Min; Jeong, Jin Young; Yang, Eun Jin; Kang, Sung-Ho; Yun, Mi Sun; Lee, Sang Heon

    2018-03-01

    Although the areal coverage of melt pond in the Arctic Ocean has recently increased, very few biological researches have been conducted. The objectives in this study were to ascertain the uptake rates of carbon and nitrogen in various melt ponds and to understand the major controlling factors for the rates. We obtained 22 melt pond samples at ice camp 1 (146.17°W, 77.38°N) and 11 melt pond samples at ice camp 2 (169.79°W, 76.52°N). The major nutrient concentrations varied largely among melt ponds at the ice camps 1 and 2. The chl-a concentrations averaged from the melt ponds at camps 1 and 2 were 0.02-0.56 mg chl-a m-3 (0.12 ± 0.12 mg chl-a m-3) and 0.08-0.30 mg chl-a m-3 (0.16 ± 0.08 mg chl-a m-3), respectively. The hourly carbon uptake rates at camps 1 and 2 were 0.001-0.080 mg C m-3 h-1 (0.025 ± 0.024 mg C m-3 h-1) and 0.022-0.210 mg C m-3 h-1 (0.077 ± 0.006 mg C m-3 h-1), respectively. In comparison, the nitrogen uptake rates at camps 1 and 2 were 0.001-0.030 mg N m-3 h-1 (0.011 ± 0.010 mg N m-3 h-1) and 0.002-0.022 mg N m-3 h-1 (0.010 ± 0.006 mg N m-3 h-1), respectively. The values obtained in this study are significantly lower than those reported previously. A large portion of algal biomass trapped in the new forming surface ice in melt ponds appears to be one of the main potential reasons for the lower chl-a concentration and subsequently lower carbon and nitrogen uptake rates revealed in this study. A long-term monitoring program on melt ponds is needed to understand the response of the Arctic marine ecosystem to ongoing environmental changes.

  9. Functional interaction between bicarbonate transporters and carbonic anhydrase modulates lactate uptake into mouse cardiomyocytes.

    PubMed

    Peetz, Jan; Barros, L Felipe; San Martín, Alejandro; Becker, Holger M

    2015-07-01

    Blood-derived lactate is a precious energy substrate for the heart muscle. Lactate is transported into cardiomyocytes via monocarboxylate transporters (MCTs) together with H(+), which couples lactate uptake to cellular pH regulation. In this study, we have investigated how the interplay between different acid/base transporters and carbonic anhydrases (CA), which catalyze the reversible hydration of CO2, modulates the uptake of lactate into isolated mouse cardiomyocytes. Lactate transport was estimated both as lactate-induced acidification and as changes in intracellular lactate levels measured with a newly developed Förster resonance energy transfer (FRET) nanosensor. Recordings of intracellular pH showed an increase in the rate of lactate-induced acidification when CA was inhibited by 6-ethoxy-2-benzothiazolesulfonamide (EZA), while direct measurements of lactate flux demonstrated a decrease in MCT transport activity, when CA was inhibited. The data indicate that catalytic activity of extracellular CA increases lactate uptake and counteracts intracellular lactate-induced acidification. We propose a hypothetical model, in which HCO3 (-), formed from cell-derived CO2 at the outer surface of the cardiomyocyte plasma membrane by membrane-anchored, extracellular CA, is transported into the cell via Na(+)/HCO3 (-) cotransport to counteract intracellular acidification, while the remaining H(+) stabilizes extracellular pH at the surface of the plasma membrane during MCT activity to enhance lactate influx into cardiomyocytes.

  10. Temporal dynamics of groundwater-dissolved inorganic carbon beneath a drought-affected braided stream: Platte River case study

    NASA Astrophysics Data System (ADS)

    Boerner, Audrey R.; Gates, John B.

    2015-05-01

    Impacts of environmental changes on groundwater carbon cycling are poorly understood despite their potentially high relevance to terrestrial carbon budgets. This study focuses on streambed groundwater chemistry during a period of drought-induced river drying and consequent disconnection between surface water and groundwater. Shallow groundwater underlying vegetated and bare portions of a braided streambed in the Platte River (Nebraska, USA) was monitored during drought conditions in summer 2012. Water temperature and dissolved inorganic carbon (dominated by HCO3-) in streambed groundwater were correlated over a 3 month period coinciding with a decline in river discharge from 35 to 0 m3 s-1. Physical, chemical, and isotopic parameters were monitored to investigate mechanisms affecting the HCO3- trend. Equilibrium thermodynamic modeling suggests that an increase of pCO2 near the water table, coupled with carbonate mineral weathering, can explain the trend. Stronger temporal trends in Ca2+ and Mg2+ compared to Cl- are consistent with carbonate mineral reequilibria rather than evaporative concentration as the primary mechanism of the increased HCO3-. Stable isotope trends are not apparent, providing further evidence of thermodynamic controls rather than evaporation from the water table. A combination of increased temperature and O2 in the dewatered portion of the streambed is the most likely driver of increased pCO2 near the water table. Results of this study highlight potential linkages between surface environmental changes and groundwater chemistry and underscore the need for high-resolution chemical monitoring of alluvial groundwater in order to identify environmental change impacts.

  11. Informing climate models with rapid chamber measurements of forest carbon uptake.

    PubMed

    Metcalfe, Daniel B; Ricciuto, Daniel; Palmroth, Sari; Campbell, Catherine; Hurry, Vaughan; Mao, Jiafu; Keel, Sonja G; Linder, Sune; Shi, Xiaoying; Näsholm, Torgny; Ohlsson, Klas E A; Blackburn, M; Thornton, Peter E; Oren, Ram

    2017-05-01

    Models predicting ecosystem carbon dioxide (CO 2 ) exchange under future climate change rely on relatively few real-world tests of their assumptions and outputs. Here, we demonstrate a rapid and cost-effective method to estimate CO 2 exchange from intact vegetation patches under varying atmospheric CO 2 concentrations . We find that net ecosystem CO 2 uptake (NEE) in a boreal forest rose linearly by 4.7 ± 0.2% of the current ambient rate for every 10 ppm CO 2 increase, with no detectable influence of foliar biomass, season, or nitrogen (N) fertilization. The lack of any clear short-term NEE response to fertilization in such an N-limited system is inconsistent with the instantaneous downregulation of photosynthesis formalized in many global models. Incorporating an alternative mechanism with considerable empirical support - diversion of excess carbon to storage compounds - into an existing earth system model brings the model output into closer agreement with our field measurements. A global simulation incorporating this modified model reduces a long-standing mismatch between the modeled and observed seasonal amplitude of atmospheric CO 2 . Wider application of this chamber approach would provide critical data needed to further improve modeled projections of biosphere-atmosphere CO 2 exchange in a changing climate. © 2016 John Wiley & Sons Ltd.

  12. Citrate- and Succinate-Modified Carbonate Apatite Nanoparticles with Loaded Doxorubicin Exhibit Potent Anticancer Activity against Breast Cancer Cells

    PubMed Central

    Mehbuba Hossain, Sultana; Chowdhury, Ezharul Hoque

    2018-01-01

    Biodegradable inorganic apatite-based particle complex is popular for its pH-sensitivity at the endosomal acidic environment to facilitate drug release following cellular uptake. Despite being a powerful anticancer drug, doxorubicin shows severe off-target effects and therefore would need a carrier for the highest effectiveness. We aimed to chemically modify carbonate apatite (CA) with Krebs cycle intermediates, such as citrate and succinate in order to control the growth of the resultant particles to more efficiently carry and transport the anticancer drug into the cancer cells. Citrate- or succinate-modified CA particles were synthesized with different concentrations of sodium citrate or sodium succinate, respectively, in the absence or presence of doxorubicin. The drug loading efficiency of the particles and their cellular uptake were observed by quantifying fluorescence intensity. The average diameter and surface charge of the particles were determined using Zetasizer. Cell viability was assessed by MTT assay. Citrate-modified carbonate apatite (CMCA) exhibited the highest (31.38%) binding affinity for doxorubicin and promoted rapid cellular uptake of the drug, leading to the half-maximal inhibitory concentration 1000 times less than that of the free drug in MCF-7 cells. Hence, CMCA nanoparticles with greater surface area enhance cytotoxicity in different breast cancer cells by enabling higher loading and more efficient cellular uptake of the drug. PMID:29534497

  13. Interactions of carbon nanotubes with aqueous/aquatic media containing organic/inorganic contaminants and selected organisms of aquatic ecosystems--A review.

    PubMed

    Boncel, Sławomir; Kyzioł-Komosińska, Joanna; Krzyżewska, Iwona; Czupioł, Justyna

    2015-10-01

    Due to their unique molecular architecture translating into numerous every-day applications, carbon nanotubes (CNTs) will be ultimately an increasingly significant environmental contaminant. This work reviews qualitative/quantitative analyses of interactions of various types of CNTs and their chemically modified analogues with aqueous/aquatic media containing organic and inorganic contaminants and selected organisms of aquatic ecosystems. A special emphasis was placed on physicochemical interactions between CNTs as adsorbents of heavy metal cations and aromatic compounds (dyes) with its environmental consequences. The studies revealed CNTs as more powerful adsorbents of aromatic compounds (an order of magnitude higher adsorption capacity) than metal cations. Depending on the presence of natural organic matter (NOM) and/or co-contaminants, CNTs may act as Trojan horse while passing through biological membranes (in the absence of NOM coordinating metal ions). Nanotubes, depending on flow conditions and their morphology/surface chemistry, may travel with natural waters or sediment with immobilized PAHs or metals and/or increase cyto- and ecotoxicity of PAHs/metal ions by their release via competitive complexation, or cause synergic ecotoxicity while adsorbing nutrients. Additionally, toxicity of CNTs against exemplary aquatic microorganisms was reviewed. It was found for Daphnia magna that longer exposures to CNTs led to higher ecotoxicity with a prolonged CNTs excretion. SWCNTs were more toxic than MWCNTs, while hydrophilization of CNTs via oxidation or anchoring thereto polar/positively charged polymer chains enhanced stability of nanotubes dispersion in aqueous media. On the other hand, bioavailability of functionalized CNTs was improved leading to more complex both mechanisms of uptake and cytotoxic effects. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Uptake of 2, 4-Dichlorophenoxyacetic acid by Pseudomonas fluorescens

    USGS Publications Warehouse

    Wedemeyer, G.A.

    1966-01-01

    Factors influencing the uptake of the sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D), under conditions in which no net metabolism occurred, were investigated in an effort to determine both the significance of “nonmetabolic” uptake as a potential agent in reducing pesticide levels and the mechanisms involved. Uptake of 2,4-D was affected by pH, temperature, and the presence of other organic and inorganic compounds. Uptake was more pronounced at pH values less than 6, which implies that there may be some interaction between charged groups on the cell and the ionized carboxyl group of 2,4-D. Active transport, carriermediated diffusion, passive diffusion, and adsorption were considered as possible mechanisms. Though uptake was inhibited by glucose, sodium azide, and fluorodinitrobenzene (but not by uranylion), 2,4-D was not accumulated against a concentration gradient, a necessary consequence of an active transport system, nor was isotope counterflow found to occur. Thus, carrier-mediated diffusion was finally precluded, implying that uptake probably occurs by a two-step process: sorption onto the cell wall followed by passive diffusion into the cytoplasm.

  15. Uptake of 2,4-dichlorophenoxyacetic acid by Pseudomonas fluorescens

    USGS Publications Warehouse

    Wedemeyer, Gary

    1966-01-01

    Factors influencing the uptake of the sodium salt of 2,4-dichlorophenoxyacetic acid (2,4-D), under conditions in which no net metabolism occurred, were investigated in an effort to determine both the significance of “non-metabolic” uptake as a potential agent in reducing pesticide levels and the mechanisms involved. Uptake of 2,4-D was affected by pH, temperature, and the presence of other organic and inorganic compounds. Uptake was more pronounced at pH values less than 6, which implies that there may be some interaction between charged groups on the cell and the ionized carboxyl group of 2,4-D. Active transport, carrier-mediated diffusion, passive diffusion, and adsorption were considered as possible mechanisms. Though uptake was inhibited by glucose, sodium azide, and fluorodinitrobenzene (but not by uranyl ion), 2,4-D was not accumulated against a concentration gradient, a necessary consequence of an active transport system, nor was isotope counterflow found to occur. Thus, carrier-mediated diffusion was finally precluded, implying that uptake probably occurs by a two-step process: sorption onto the cell wall followed by passive diffusion into the cytoplasm.

  16. Effect of injection routes on the biodistribution, clearance, and tumor uptake of carbon dots.

    PubMed

    Huang, Xinglu; Zhang, Fan; Zhu, Lei; Choi, Ki Young; Guo, Ning; Guo, Jinxia; Tackett, Kenneth; Anilkumar, Parambath; Liu, Gang; Quan, Qimeng; Choi, Hak Soo; Niu, Gang; Sun, Ya-Ping; Lee, Seulki; Chen, Xiaoyuan

    2013-07-23

    The emergence of photoluminescent carbon-based nanomaterials has shown exciting potential in the development of benign nanoprobes. However, the in vivo kinetic behaviors of these particles that are necessary for clinical translation are poorly understood to date. In this study, fluorescent carbon dots (C-dots) were synthesized and the effect of three injection routes on their fate in vivo was explored by using both near-infrared fluorescence and positron emission tomography imaging techniques. We found that C-dots are efficiently and rapidly excreted from the body after all three injection routes. The clearance rate of C-dots is ranked as intravenous > intramuscular > subcutaneous. The particles had relatively low retention in the reticuloendothelial system and showed high tumor-to-background contrast. Furthermore, different injection routes also resulted in different blood clearance patterns and tumor uptakes of C-dots. These results satisfy the need for clinical translation and should promote efforts to further investigate the possibility of using carbon-based nanoprobes in a clinical setting. More broadly, we provide a testing blueprint for in vivo behavior of nanoplatforms under various injection routes, an important step forward toward safety and efficacy analysis of nanoparticles.

  17. Selective uptake of multi-walled carbon nanotubes by tumor macrophages in a murine glioma model.

    PubMed

    VanHandel, Michelle; Alizadeh, Darya; Zhang, Leying; Kateb, Babak; Bronikowski, Michael; Manohara, Harish; Badie, Behnam

    2009-03-31

    Carbon nantotubes (CNTs) are emerging as a new family of nanovectors for drug and gene delivery into biological systems. To evaluate potential application of this technology for brain tumor therapy, we studied uptake and toxicity of multi-walled CNTs (MWCNTs) in the GL261 murine intracranial glioma model. Within 24 h of a single intratumoral injection of labeled MWCNTs (5 microg), nearly 10-20% of total cells demonstrated CNT internalization. Most CNT uptake, however, occurred by tumor-associated macrophages (MP), which accounted for most (75%) MWCNT-positive cells. Within 24 h of injection, nearly 30% of tumor MP became MWCNT-positive. Despite a transient increase in inflammatory cell infiltration into both normal and tumor-bearing brains following MWCNT injection, no significant toxicity was noted in mice, and minor changes in tumor cytokine expression were observed. This study suggests that MWCNTs could potentially be used as a novel and non-toxic vehicle for targeting MP in brain tumors.

  18. [Effects of long-term fertilization on microbial biomass carbon and nitrogen and on carbon source utilization of microbes in a red soil].

    PubMed

    Sun, Feng-xia; Zhang, Wei-hua; Xu, Ming-gang; Zhang, Wen-ju; Li, Zhao-qiang; Zhang, Jing-ye

    2010-11-01

    In order to explore the effects of long-term fertilization on the microbiological characters of red soil, soil samples were collected from a 19-year long-term experimental field in Qiyang of Hunan, with their microbial biomass carbon (MBC) and nitrogen (MBN) and microbial utilization ratio of carbon sources analyzed. The results showed that after 19-year fertilization, the soil MBC and MBN under the application of organic manure and of organic manure plus inorganic fertilizers were 231 and 81 mg x kg(-1) soil, and 148 and 73 mg x kg(-1) soil, respectively, being significantly higher than those under non-fertilization, inorganic fertilization, and inorganic fertilization plus straw incorporation. The ratio of soil MBN to total N under the application of organic manure and of organic manure plus inorganic fertilizers was averagely 6.0%, significantly higher than that under non-fertilization and inorganic fertilization. Biolog-ECO analysis showed that the average well color development (AWCD) value was in the order of applying organic manure plus inorganic fertilizers = applying organic manure > non-fertilization > inorganic fertilization = inorganic fertilization plus straw incorporation. Under the application of organic manure or of organic manure plus inorganic fertilizers, the microbial utilization rate of carbon sources, including carbohydrates, carboxylic acids, amino acids, polymers, phenols, and amines increased; while under inorganic fertilization plus straw incorporation, the utilization rate of polymers was the highest, and that of carbohydrates was the lowest. Our results suggested that long-term application of organic manure could increase the red soil MBC, MBN, and microbial utilization rate of carbon sources, improve soil fertility, and maintain a better crop productivity.

  19. Carbon Nanotubes Enhance CpG Uptake and Potentiate Anti-Glioma Immunity

    PubMed Central

    Zhao, Dongchang; Alizadeh, Darya; Zhang, Leying; Liu, Wei; Farrukh, Omar; Manuel, Edwin; Diamond, Don J.; Badie, Behnam

    2010-01-01

    Purpose Stimulation of toll-like receptor-9 (TLR9) by CpG oligodeoxynucleotides (CpG) has been shown to counteract the immunosuppressive microenvironment and to inhibit tumor growth in glioma models. Since TLR9 is located intracellularly, we hypothesized that methods that enhance its internalization may also potentiate its immunostimulatory response. The goal of this study was to evaluate carbon nanotubes (CNTs) as a CpG delivery vehicle in brain tumor models. Experimental Design Functionalized single-walled CNTs were conjugated with CpG (CNT-CpG) and evaluated in vitro and in mice bearing intracranial GL261 gliomas. Flow cytometry was used to assess CNT-CpG uptake and anti-glioma immune response. Tumor growth was measured by bioluminescent imaging, histology, and animal survival. Results CNT-CpG was nontoxic and enhanced CpG uptake both in vitro and intracranial gliomas. CNT-mediated CpG delivery also potentiated pro-inflammatory cytokine production by primary monocytes. Interestingly, a single intracranial injection of low-dose CNT-CpG (but not free CpG or blank CNT) eradicated intracranial GL261 gliomas in half of tumor-bearing mice. Moreover, surviving animals exhibited durable tumor-free remission (> 3 months), and were protected from intracranial tumor rechallenge, demonstrating induction of long-term anti-tumor immunity. Conclusions These findings suggest that CNTs can potentiate CpG immunopotency by enhancing its delivery into tumor-associated inflammatory cells. PMID:21088258

  20. Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

    NASA Astrophysics Data System (ADS)

    Jones, Elizabeth M.; Bakker, Dorothee C. E.; Venables, Hugh J.; Whitehouse, Michael J.; Korb, Rebecca E.; Watson, Andrew J.

    2010-11-01

    ABSTRACT The effect of sea ice melt on the carbonate chemistry of surface waters in the Weddell-Scotia Confluence, Southern Ocean, was investigated during January 2008. Contrasting concentrations of dissolved inorganic carbon (DIC), total alkalinity (TA) and the fugacity of carbon dioxide (fCO2) were observed in and around the receding sea ice edge. The precipitation of carbonate minerals such as ikaite (CaCO3.6H2O) in sea ice brine has the net effect of decreasing DIC and TA and increasing the fCO2 in the brine. Deficits in DIC up to 12 +/- 3 μmol kg-1 in the marginal ice zone (MIZ) were consistent with the release of DIC-poor brines to surface waters during sea ice melt. Biological utilization of carbon was the dominant processes and accounted for 41 +/- 1 μmol kg-1 of the summer DIC deficit. The data suggest that the combined effects of biological carbon uptake and the precipitation of carbonates created substantial undersaturation in fCO2 of 95 μatm in the MIZ during summer sea ice melt. Further work is required to improve the understanding of ikaite chemistry in Antarctic sea ice and its importance for the sea ice carbon pump.

  1. Inorganic nanoparticles in diagnosis and treatment of breast cancer.

    PubMed

    Núñez, Cristina; Estévez, Sergio Vázquez; Del Pilar Chantada, María

    2018-05-01

    Nanoparticles are being actively developed for biomolecular profiling of cancer biomarkers, tumor imaging in vivo, and targeted drug delivery. These nanotechnology-based techniques can be applied widely in the management of different malignant diseases, such as breast cancer. Although the number of different types of nanoparticles is increasing rapidly, most can be classified into two major types: particles that contain organic molecules as a major building material (such as dendrimers, micelles, liposomes and carbon nanotubes, and other polymers); and those that use inorganic elements, usually metals, as a core. In particular, inorganic nanoparticles have received increased attention in the recent past as potential diagnostic and therapeutic systems in the field of oncology. This review primarily discusses progress in applications of inorganic nanoparticles for breast cancer imaging and treatment.

  2. Functional Traits for Carbon Access in Macrophytes

    PubMed Central

    Pfister, Catherine A.; Wootton, J. Timothy

    2016-01-01

    Understanding functional trait distributions among organisms can inform impacts on and responses to environmental change. In marine systems, only 1% of dissolved inorganic carbon in seawater exists as CO2. Thus the majority of marine macrophytes not only passively access CO2 for photosynthesis, but also actively transport CO2 and the more common bicarbonate (HCO3-, 92% of seawater dissolved inorganic carbon) into their cells. Because species with these carbon concentrating mechanisms (CCMs) are non-randomly distributed in ecosystems, we ask whether there is a phylogenetic pattern to the distribution of CCMs among algal species. To determine macrophyte traits that influence carbon uptake, we assessed 40 common macrophyte species from the rocky intertidal community of the Northeast Pacific Ocean to a) query whether macrophytes have a CCM and b) determine the evolutionary history of CCMs, using ancestral state reconstructions and stochastic character mapping based on previously published data. Thirty-two species not only depleted CO2, but also concentrated and depleted HCO3-, indicative of a CCM. While analysis of CCMs as a continuous trait in 30 families within Phylum Rhodophyta showed a significant phylogenetic signal under a Brownian motion model, analysis of CCMs as a discrete trait (presence or absence) indicated that red algal families are more divergent than expected in their CCM presence or absence; CCMs are a labile trait within the Rhodophyta. In contrast, CCMs were present in each of 18 Ochrophyta families surveyed, indicating that CCMs are highly conserved in the brown algae. The trait of CCM presence or absence was largely conserved within Families. Fifteen of 23 species tested also changed the seawater buffering capacity, or Total Alkalinity (TA), shifting DIC composition towards increasing concentrations of HCO3- and CO2 for photosynthesis. Manipulating the external TA of the local environment may influence carbon availability in boundary layers and

  3. Use of carbonates for biological and chemical synthesis

    DOEpatents

    Rau, Gregory Hudson

    2014-09-09

    A system of using carbonates, especially water-insoluble or sparing soluble mineral carbonates, for maintaining or increasing dissolved inorganic carbon concentrations in aqueous media. In particular, the system generates concentrated dissolve inorganic carbon substrates for photosynthetic, chemosynthetic, or abiotic chemical production of carbonaceous or other compounds in solution. In some embodiments, the invention can also enhance the dissolution and retention of carbon dioxide in aqueous media, and can produce pH buffering capacity, metal ions, and heat, which can be beneficial to the preceding syntheses.

  4. Abundances and test weights of living planktic foraminifers across the Southwest Indian Ocean: Implications for carbon fluxes

    NASA Astrophysics Data System (ADS)

    Meilland, J.; Schiebel, R.; Lo Monaco, C.; Sanchez, S.; Howa, H.

    2018-01-01

    Calcifying marine organisms include planktic foraminifers that contribute to the marine carbon turnover by generating inorganic carbon production (CaCO3, shell) and flux. In this study, we have analyzed assemblages at the morphospecies level and abundances of living planktic foraminifers (LPF) from ten stations located in the Southwest Indian Ocean, and sampled in austral summer 2012. LPF density ranges from zero in the Subtropical Zone (STZ) to 944 individuals m-3 in the Polar Frontal Zone (PFZ), and is composed by up to 80% by the four species Neogloboquadrina pachyderma, Neogloboquadrina incompta, Globigerina bulloides, and Globigerinita uvula. For the entire region, we measured the individual morphometry and test mass (CaCO3) of 454 tests of living planktic foraminifers in order to calculate inorganic carbon standing stocks, as well as carbon flux. In the STZ, the average daily planktic foraminifer CaCO3 flux at 100 m water depth is low (< 0.22 mg m-2 d-1), whereas south of the Sub-Antarctic Zone (SAZ), in the PFZ and Antarctic Zone (AAZ), it reaches up to 49.41 mg m-2 d-1, and 2.20 mg m-2 d-1, respectively. The large regional variability in CaCO3 production and flux of LPF assemblages affects the marine carbonate system to varying degrees, depending on hydrological conditions. We conclude that recent changes in the position of hydrological fronts could induce a decrease in the LPF-related carbonate counter pump, which increases the oceanic uptake of CO2, and counteracts climate warming.

  5. Photostability and moisture uptake properties of wood veneers coated with a combination of thin sol-gel films and light stabilizers

    Treesearch

    Mandla A. Tshabalala; Ryan Libert; Christian M. Schaller

    2011-01-01

    In recent years, there has been increased interest in the use of inorganic UV blocking nanoparticles for photostabilization of wood surfaces. Photostability and moisture uptake properties of wood veneers coated with a combination of hybrid inorganic-organic thin sol-gel films and organic light stabilizers was investigated. The light stabilizers were applied by brushing...

  6. 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.

  7. Organic and inorganic carbon dynamics in a karst aquifer: Santa Fe River Sink-Rise system, north Florida, USA

    NASA Astrophysics Data System (ADS)

    Jin, Jin; Zimmerman, Andrew R.; Moore, Paul J.; Martin, Jonathan B.

    2014-03-01

    Spatiotemporal variations in dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), major ions concentrations and other geochemical parameters including stable carbon isotopes of DIC (δ13CDIC), were measured in surface water and deep and shallow well water samples of the Santa Fe River Sink-Rise eogenetic karst system, north Florida, USA. Three end-member water sources were identified: one DOC-rich/DIC-poor/δ13CDIC-depleted, one DOC-poor/DIC-rich/δ13CDIC-enriched, and one enriched in major ions. Given their spatiotemporal distributions, they were presumed to represent soil water, upper aquifer groundwater, and deep aquifer water sources, respectively. Using assumed ratios of Na+, Cl, and SO42- for each end-member, a mixing model calculated the contribution of each water source to each sample. Then, chemical effects of biogeochemical reactions were calculated as the difference between those predicted by the mixing model and measured species concentrations. In general, carbonate mineral dissolution occurred throughout the Sink-Rise system, surface waters were net autotrophic and the subsurface was in metabolic balance, i.e., no net DOC or DIC production or consumption. However, there was evidence for chemolithoautotrophy, perhaps by hydrogen oxidizing microbes, at some deep aquifer sites. Mineralization of this autochthonous natural dissolved organic matter (NDOM) led to localized carbonate dissolution as did surface water-derived NDOM supplied to shallow well sites during the highest flow periods. This study demonstrates linkages between hydrology, abiotic and microbial processes and carbon dynamics and has important implications for groundwater quality, karst morphologic evolution, and hydrogeologic projects such as aquifer storage and recovery in karst systems.

  8. Soft templating strategies for the synthesis of mesoporous materials: inorganic, organic-inorganic hybrid and purely organic solids.

    PubMed

    Pal, Nabanita; Bhaumik, Asim

    2013-03-01

    With the discovery of MCM-41 by Mobil researchers in 1992 the journey of the research on mesoporous materials started and in the 21st century this area of scientific investigation have extended into numerous branches, many of which contribute significantly in emerging areas like catalysis, energy, environment and biomedical research. As a consequence thousands of publications came out in large varieties of national and international journals. In this review, we have tried to summarize the published works on various synthetic pathways and formation mechanisms of different mesoporous materials viz. inorganic, organic-inorganic hybrid and purely organic solids via soft templating pathways. Generation of nanoscale porosity in a solid material usually requires participation of organic template (more specifically surfactants and their supramolecular assemblies) called structure-directing agent (SDA) in the bottom-up chemical reaction process. Different techniques employed for the syntheses of inorganic mesoporous solids, like silicas, metal doped silicas, transition and non-transition metal oxides, mixed oxides, metallophosphates, organic-inorganic hybrids as well as purely organic mesoporous materials like carbons, polymers etc. using surfactants are depicted schematically and elaborately in this paper. Moreover, some of the frontline applications of these mesoporous solids, which are directly related to their functionality, composition and surface properties are discussed at the appropriate places. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. The role of internal variability for decadal carbon uptake anomalies in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Spring, Aaron; Hi, Hongmei; Ilyina, Tatiana

    2017-04-01

    The Southern Ocean is a major sink for anthropogenic CO2 emissions and hence it plays an essential role in modulating global carbon cycle and climate change. Previous studies based on observations (e.g., Landschützer et al. 2015) show pronounced decadal variations of carbon uptake in the Southern Ocean in recent decades and this variability is largely driven by internal climate variability. However, due to limited ensemble size of simulations, the variability of this important ocean sink is still poorly assessed by the state-of-the-art earth system models (ESMs). To assess the internal variability of carbon sink in the Southern Ocean, we use a large ensemble of 100 member simulations based on the Max Planck Institute-ESM (MPI-ESM). The large ensemble of simulations is generated via perturbed initial conditions in the ocean and atmosphere. Each ensemble member includes a historical simulation from 1850 to 2005 with an extension until 2100 under Representative Concentration Pathway (RCP) 4.5 future projections. Here we use model simulations from 1980-2015 to compare with available observation-based dataset. We found several ensemble members showing decadal decreasing trends in the carbon sink, which are similar to the trend shown in observations. This result suggests that MPI-ESM large ensemble simulations are able to reproduce decadal variation of carbon sink in the Southern Ocean. Moreover, the decreasing trends of Southern Ocean carbon sink in MPI-ESM are mainly contributed by region between 50-60°S. To understand the internal variability of the air-sea carbon fluxes in the Southern Ocean, we further investigate the variability of underlying processes, such as physical climate variability and ocean biological processes. Our results indicate two main drivers for the decadal decreasing trend of carbon sink: i) Intensified winds enhance upwelling of old carbon-rich waters, this leads to increase of the ocean surface pCO2; ii) Primary production is reduced in area

  10. Strong constraint on modelled global carbon uptake using solar-induced chlorophyll fluorescence data.

    PubMed

    MacBean, Natasha; Maignan, Fabienne; Bacour, Cédric; Lewis, Philip; Peylin, Philippe; Guanter, Luis; Köhler, Philipp; Gómez-Dans, Jose; Disney, Mathias

    2018-01-31

    Accurate terrestrial biosphere model (TBM) simulations of gross carbon uptake (gross primary productivity - GPP) are essential for reliable future terrestrial carbon sink projections. However, uncertainties in TBM GPP estimates remain. Newly-available satellite-derived sun-induced chlorophyll fluorescence (SIF) data offer a promising direction for addressing this issue by constraining regional-to-global scale modelled GPP. Here, we use monthly 0.5° GOME-2 SIF data from 2007 to 2011 to optimise GPP parameters of the ORCHIDEE TBM. The optimisation reduces GPP magnitude across all vegetation types except C4 plants. Global mean annual GPP therefore decreases from 194 ± 57 PgCyr -1 to 166 ± 10 PgCyr -1 , bringing the model more in line with an up-scaled flux tower estimate of 133 PgCyr -1 . Strongest reductions in GPP are seen in boreal forests: the result is a shift in global GPP distribution, with a ~50% increase in the tropical to boreal productivity ratio. The optimisation resulted in a greater reduction in GPP than similar ORCHIDEE parameter optimisation studies using satellite-derived NDVI from MODIS and eddy covariance measurements of net CO 2 fluxes from the FLUXNET network. Our study shows that SIF data will be instrumental in constraining TBM GPP estimates, with a consequent improvement in global carbon cycle projections.

  11. Patterns and Trends of Primary Production, Inorganic Carbon and Oxygen and Their Ecosystem Impacts in a Regional Biogeochemical Ocean Model for Atlantic Canada

    NASA Astrophysics Data System (ADS)

    Fennel, K.; Rutherford, K. E.; Kuhn, A. M.; Zhang, W.; Brennan, C. E.; Zhang, R.

    2016-12-01

    Representing coastal oceans in global biogeochemical models is a challenge, yet the ecosystems in these regions are most vulnerable to the combined stressors of ocean warming, deoxygenation, acidification, eutrophication and fishing. Coastal regions also have large air-sea fluxes of CO2, making them an important but poorly quantified component of the global carbon cycle, and are the most relevant for human activities. Regional model applications that are nested within large-scale or global models are necessary for detailed studies of coastal regions. We present results from such a regional biogeochemical model for the northwestern North Atlantic shelves and adjacent deep ocean of Atlantic Canada. The model is an implementation of the Regional Ocean Modeling System (ROMS) and includes an NPZD-type nitrogen cycle model with explicit representation of dissolved oxygen and inorganic carbon. The region is at the confluence of the Gulf Stream and Labrador Current making it highly dynamic, a challenge for analysis and prediction, and prone to large changes. Historically a rich fishing ground, coastal ecosystems in Atlantic Canada have undergone dramatic changes including the collapse of several economically important fish stocks and the listing of many species as threatened or endangered. Furthermore it is unclear whether the region is a net source or sink of atmospheric CO2 with estimates of the size and direction of the net air-sea CO2 flux remaining controversial. We will discuss simulated patterns of primary production, inorganic carbon fluxes and oxygen trends in the context of circulation features and shelf residence times for the present ocean state and present future projections.

  12. Automated determination of the stable carbon isotopic composition (δ13C) of total dissolved inorganic carbon (DIC) and total nonpurgeable dissolved organic carbon (DOC) in aqueous samples: RSIL lab codes 1851 and 1852

    USGS Publications Warehouse

    Révész, Kinga M.; Doctor, Daniel H.

    2014-01-01

    The purposes of the Reston Stable Isotope Laboratory (RSIL) lab codes 1851 and 1852 are to determine the total carbon mass and the ratio of the stable isotopes of carbon (δ13C) for total dissolved inorganic carbon (DIC, lab code 1851) and total nonpurgeable dissolved organic carbon (DOC, lab code 1852) in aqueous samples. The analysis procedure is automated according to a method that utilizes a total carbon analyzer as a peripheral sample preparation device for analysis of carbon dioxide (CO2) gas by a continuous-flow isotope ratio mass spectrometer (CF-IRMS). The carbon analyzer produces CO2 and determines the carbon mass in parts per million (ppm) of DIC and DOC in each sample separately, and the CF-IRMS determines the carbon isotope ratio of the produced CO2. This configuration provides a fully automated analysis of total carbon mass and δ13C with no operator intervention, additional sample preparation, or other manual analysis. To determine the DIC, the carbon analyzer transfers a specified sample volume to a heated (70 °C) reaction vessel with a preprogrammed volume of 10% phosphoric acid (H3PO4), which allows the carbonate and bicarbonate species in the sample to dissociate to CO2. The CO2 from the reacted sample is subsequently purged with a flow of helium gas that sweeps the CO2 through an infrared CO2 detector and quantifies the CO2. The CO2 is then carried through a high-temperature (650 °C) scrubber reactor, a series of water traps, and ultimately to the inlet of the mass spectrometer. For the analysis of total dissolved organic carbon, the carbon analyzer performs a second step on the sample in the heated reaction vessel during which a preprogrammed volume of sodium persulfate (Na2S2O8) is added, and the hydroxyl radicals oxidize the organics to CO2. Samples containing 2 ppm to 30,000 ppm of carbon are analyzed. The precision of the carbon isotope analysis is within 0.3 per mill for DIC, and within 0.5 per mill for DOC.

  13. Inter-annual variation of carbon uptake by a plantation oak woodland in south-eastern England

    NASA Astrophysics Data System (ADS)

    Wilkinson, M.; Eaton, E. L.; Broadmeadow, M. S. J.; Morison, J. I. L.

    2012-12-01

    The carbon balance of an 80-yr-old deciduous oak plantation in the temperate oceanic climate of the south-east of Great Britain was measured by eddy covariance over 12 yr (1999-2010). The mean annual net ecosystem productivity (NEP) was 486 g C m-2 yr-1 (95% CI of ±73 g C m-2 yr-1), and this was partitioned into a gross primary productivity (GPP) of 2034 ± 145 g C m-2 yr-1, over a 165 (±6) day growing season, and an annual loss of carbon through respiration and decomposition (ecosystem respiration, Reco) of 1548 ± 122 g C m-2 yr-1. Although the maximum variation of NEP between years was large (333 g C m-2 yr-1), the ratio of Reco/GPP remained relatively constant (0.76 ± 0.02 CI). Some anomalies in the annual patterns of the carbon balance could be linked to particular weather events, such as low summer solar radiation and low soil moisture content (values below 30% by volume). The European-wide heat wave and drought of 2003 did not reduce the NEP of this woodland because of good water supply from the surface-water gley soil. The inter-annual variation in estimated intercepted radiation only accounted for ~ 47% of the variation in GPP, although a significant relationship (p < 0.001) was found between peak leaf area index and annual GPP, which modified the efficiency with which incident radiation was used in net CO2 uptake. Whilst the spring start and late autumn end of the net CO2 uptake period varied substantially (range of 24 and 27 days respectively), annual GPP was not related to growing season length. Severe outbreaks of defoliating moth caterpillars, mostly Tortrix viridana L. and Operophtera brumata L., caused considerable damage to the forest canopy in 2009 and 2010, resulting in reduced GPP in these two years. Inter-annual variation in the sensitivity of Reco to temperature was found to be strongly related to summer soil moisture content. The eddy covariance estimates of NEP closely matched mensuration-based estimates, demonstrating that this forest

  14. Inorganic Nanoparticle-Modified Poly(Phenylene Sulphide)/ Carbon Fiber Laminates: Thermomechanical Behaviour.

    PubMed

    Díez-Pascual, Ana M; Naffakh, Mohammed

    2013-07-26

    Carbon fiber (CF)-reinforced high-temperature thermoplastics such as poly(phenylene sulphide) (PPS) are widely used in structural composites for aerospace and automotive applications. The porosity of CF-reinforced polymers is a very important topic for practical applications since there is a direct correlation between void content and mechanical properties. In this study, inorganic fullerene-like tungsten disulphide (IF-WS₂) lubricant nanoparticles were used to manufacture PPS/IF-WS₂/CF laminates via melt-blending and hot-press processing, and the effect of IF-WS₂ loading on the quality, thermal and mechanical behaviour of the hybrid composites was investigated. The addition of IF-WS₂ improved fiber impregnation, resulting in lower degree of porosity and increased delamination resistance, compression and flexural properties; their reinforcement effect was greater at temperatures above the glass transition (T g ). IF-WS₂ contents higher than 0.5 wt % increased T g and the heat deflection temperature while reduced the coefficient of thermal expansion. The multiscale laminates exhibited higher ignition point and notably reduced peak heat release rate compared to PPS/CF. The coexistence of micro- and nano-scale fillers resulted in synergistic effects that enhanced the stiffness, strength, thermal conductivity and flame retardancy of the matrix. The results presented herein demonstrate that the IF-WS₂ are very promising nanofillers to improve the thermomechanical properties of conventional thermoplastic/CF composites.

  15. Inorganic Nanoparticle-Modified Poly(Phenylene Sulphide)/Carbon Fiber Laminates: Thermomechanical Behaviour

    PubMed Central

    Díez-Pascual, Ana M.; Naffakh, Mohammed

    2013-01-01

    Carbon fiber (CF)-reinforced high-temperature thermoplastics such as poly(phenylene sulphide) (PPS) are widely used in structural composites for aerospace and automotive applications. The porosity of CF-reinforced polymers is a very important topic for practical applications since there is a direct correlation between void content and mechanical properties. In this study, inorganic fullerene-like tungsten disulphide (IF-WS2) lubricant nanoparticles were used to manufacture PPS/IF-WS2/CF laminates via melt-blending and hot-press processing, and the effect of IF-WS2 loading on the quality, thermal and mechanical behaviour of the hybrid composites was investigated. The addition of IF-WS2 improved fiber impregnation, resulting in lower degree of porosity and increased delamination resistance, compression and flexural properties; their reinforcement effect was greater at temperatures above the glass transition (Tg). IF-WS2 contents higher than 0.5 wt % increased Tg and the heat deflection temperature while reduced the coefficient of thermal expansion. The multiscale laminates exhibited higher ignition point and notably reduced peak heat release rate compared to PPS/CF. The coexistence of micro- and nano-scale fillers resulted in synergistic effects that enhanced the stiffness, strength, thermal conductivity and flame retardancy of the matrix. The results presented herein demonstrate that the IF-WS2 are very promising nanofillers to improve the thermomechanical properties of conventional thermoplastic/CF composites. PMID:28811429

  16. A defect in carbon catabolite repression associated with uncontrollable and excessive maltose uptake.

    PubMed

    Entian, K D

    1980-01-01

    The previously isolated recessive mutant allele hex2-3 of Saccharomyces cerevisiae caused a defect in carbon catabolite repression of maltase, invertase, malate dehydrogenase, and respiration but at the same time led to an extreme sensitivity to maltose (Zimmerman and Scheel, 1977; Entian and Zimmermann, 1980). Addition of maltose to a growing culture of a hex2-3 mutant resulted within 60 to 90 min in an inhibition of growth, glycolysis, and de novo protein synthesis. This was not accompanied by any abnormal levels of glycolysis metabolites or glycolytic enzyme activities. However, inhibitory effects coincided with a dramatic increase in intracellular glucose up to 150 mM relative to cell water as opposed to 2.5 mM in wild-type cells. This abnormal behavior is interpreted as a result of an uncontrolled maltose uptake in hex2 mutants, which in combination with increasing maltase activity results in an accumulation of intracellular glucose. Obviously the amount of available glucose surpassed glycolytic capacity in hex2 mutants. Properties of mutant alleles hex2 and hex1 (see Entian and Zimmermann, 1980) clearly show, that specific gene functions are involved in adapting the rate of sugar uptake into the cell to the actual glycolytic capacity.

  17. Carbon mineralization in Laptev and East Siberian sea shelf and slope sediment

    NASA Astrophysics Data System (ADS)

    Brüchert, Volker; Bröder, Lisa; Sawicka, Joanna E.; Tesi, Tommaso; Joye, Samantha P.; Sun, Xiaole; Semiletov, Igor P.; Samarkin, Vladimir A.

    2018-01-01

    The Siberian Arctic Sea shelf and slope is a key region for the degradation of terrestrial organic material transported from the organic-carbon-rich permafrost regions of Siberia. We report on sediment carbon mineralization rates based on O2 microelectrode profiling; intact sediment core incubations; 35S-sulfate tracer experiments; pore-water dissolved inorganic carbon (DIC); δ13CDIC; and iron, manganese, and ammonium concentrations from 20 shelf and slope stations. This data set provides a spatial overview of sediment carbon mineralization rates and pathways over large parts of the outer Laptev and East Siberian Arctic shelf and slope and allows us to assess degradation rates and efficiency of carbon burial in these sediments. Rates of oxygen uptake and iron and manganese reduction were comparable to temperate shelf and slope environments, but bacterial sulfate reduction rates were comparatively low. In the topmost 50 cm of sediment, aerobic carbon mineralization dominated degradation and comprised on average 84 % of the depth-integrated carbon mineralization. Oxygen uptake rates and anaerobic carbon mineralization rates were higher in the eastern East Siberian Sea shelf compared to the Laptev Sea shelf. DIC / NH4+ ratios in pore waters and the stable carbon isotope composition of remineralized DIC indicated that the degraded organic matter on the Siberian shelf and slope was a mixture of marine and terrestrial organic matter. Based on dual end-member calculations, the terrestrial organic carbon contribution varied between 32 and 36 %, with a higher contribution in the Laptev Sea than in the East Siberian Sea. Extrapolation of the measured degradation rates using isotope end-member apportionment over the outer shelf of the Laptev and East Siberian seas suggests that about 16 Tg C yr-1 is respired in the outer shelf seafloor sediment. Of the organic matter buried below the oxygen penetration depth, between 0.6 and 1.3 Tg C yr-1 is degraded by anaerobic processes

  18. Effects of H ₂SO₄ and O ₂ on Hg⁰ uptake capacity and reversibility of sulfur-impregnated activated carbon under dynamic conditions.

    PubMed

    Wei, Yuanyang; Yu, Danqing; Tong, Shitang; Jia, Charles Q

    2015-02-03

    Powder activated carbon (AC) injection is widely considered as the most viable technology for removing gaseous elemental mercury (Hg(0)) in flue gases of coal-fired power plants. However, sulfuric acid (H2SO4) can form on the external and internal surfaces of AC particles due to the presence of sulfur oxides, nitrogen oxides, oxygen, and moisture in flue gases. This work focuses on the effects of H2SO4 and O2 on the Hg(0) uptake capacity and reversibility of sulfur impregnated activated carbon (SIAC) under dynamic conditions. Experiments were conducted with 25 μg-Hg(0)/m(3) of nitrogen or air, using a semicontinuous flow fixed-bed reactor kept at 120 or 180 °C. H2SO4 had a profound hindering effect on Hg(0) uptake due to pore blockage. O2 significantly enhanced Hg(0) uptake and its reversibility, via the oxidation of Hg(0) which facilitated chemisorption and the subsequent physisorption onto chemically adsorbed Hg. Absorption of Hg in H2SO4 was unlikely a significant contributor, when Hg(0) concentrations were at levels of typical power plants (tens of ppb). The reversibility of and relative contributions of physisorption and chemisorption to Hg(0) uptake would change with Hg(0) concentrations in flue gases. These findings could be significant in developing a complete solution for Hg capture where the handling of spent sorbent materials and the possible secondary pollution need to be considered.

  19. Fertilization increases paddy soil organic carbon density.

    PubMed

    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

    2012-04-01

    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.

  20. 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

  1. Towards a universal model for carbon dioxide uptake by plants

    DOE PAGES

    Wang, Han; Prentice, I. Colin; Keenan, Trevor F.; ...

    2017-09-04

    Gross primary production (GPP) - the uptake of carbon dioxide (CO 2) by leaves, and its conversion to sugars by photosynthesis - is the basis for life on land. Earth System Models (ESMs) incorporating the interactions of land ecosystems and climate are used to predict the future of the terrestrial sink for anthropogenic CO 2. ESMs require accurate representation of GPP. However, current ESMs disagree on how GPP responds to environmental variations, suggesting a need for a more robust theoretical framework for modelling. Here in this work, we focus on a key quantity for GPP, the ratio of leaf internalmore » to external CO 2 (χ). χ is tightly regulated and depends on environmental conditions, but is represented empirically and incompletely in today's models. We show that a simple evolutionary optimality hypothesis predicts specific quantitative dependencies of χ on temperature, vapour pressure deficit and elevation; and that these same dependencies emerge from an independent analysis of empirical χ values, derived from a worldwide dataset of >3,500 leaf stable carbon isotope measurements. A single global equation embodying these relationships then unifies the empirical light-use efficiency model with the standard model of C 3 photosynthesis, and successfully predicts GPP measured at eddy-covariance flux sites. This success is notable given the equation's simplicity and broad applicability across biomes and plant functional types. Finally, it provides a theoretical underpinning for the analysis of plant functional coordination across species and emergent properties of ecosystems, and a potential basis for the reformulation of the controls of GPP in next-generation ESMs.« less

  2. Towards a universal model for carbon dioxide uptake by plants

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Han; Prentice, I. Colin; Keenan, Trevor F.

    Gross primary production (GPP) - the uptake of carbon dioxide (CO 2) by leaves, and its conversion to sugars by photosynthesis - is the basis for life on land. Earth System Models (ESMs) incorporating the interactions of land ecosystems and climate are used to predict the future of the terrestrial sink for anthropogenic CO 2. ESMs require accurate representation of GPP. However, current ESMs disagree on how GPP responds to environmental variations, suggesting a need for a more robust theoretical framework for modelling. Here in this work, we focus on a key quantity for GPP, the ratio of leaf internalmore » to external CO 2 (χ). χ is tightly regulated and depends on environmental conditions, but is represented empirically and incompletely in today's models. We show that a simple evolutionary optimality hypothesis predicts specific quantitative dependencies of χ on temperature, vapour pressure deficit and elevation; and that these same dependencies emerge from an independent analysis of empirical χ values, derived from a worldwide dataset of >3,500 leaf stable carbon isotope measurements. A single global equation embodying these relationships then unifies the empirical light-use efficiency model with the standard model of C 3 photosynthesis, and successfully predicts GPP measured at eddy-covariance flux sites. This success is notable given the equation's simplicity and broad applicability across biomes and plant functional types. Finally, it provides a theoretical underpinning for the analysis of plant functional coordination across species and emergent properties of ecosystems, and a potential basis for the reformulation of the controls of GPP in next-generation ESMs.« less

  3. The Impact of Variable Phytoplankton Stoichiometry on Projections of Primary Production, Food Quality, and Carbon Uptake in the Global Ocean

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, Lester; Aumont, Olivier; Bopp, Laurent; Ciais, Philippe

    2018-04-01

    Ocean biogeochemical models are integral components of Earth system models used to project the evolution of the ocean carbon sink, as well as potential changes in the physical and chemical environment of marine ecosystems. In such models the stoichiometry of phytoplankton C:N:P is typically fixed at the Redfield ratio. The observed stoichiometry of phytoplankton, however, has been shown to considerably vary from Redfield values due to plasticity in the expression of phytoplankton cell structures with different elemental compositions. The intrinsic structure of fixed C:N:P models therefore has the potential to bias projections of the marine response to climate change. We assess the importance of variable stoichiometry on 21st century projections of net primary production, food quality, and ocean carbon uptake using the recently developed Pelagic Interactions Scheme for Carbon and Ecosystem Studies Quota (PISCES-QUOTA) ocean biogeochemistry model. The model simulates variable phytoplankton C:N:P stoichiometry and was run under historical and business-as-usual scenario forcing from 1850 to 2100. PISCES-QUOTA projects similar 21st century global net primary production decline (7.7%) to current generation fixed stoichiometry models. Global phytoplankton N and P content or food quality is projected to decline by 1.2% and 6.4% over the 21st century, respectively. The largest reductions in food quality are in the oligotrophic subtropical gyres and Arctic Ocean where declines by the end of the century can exceed 20%. Using the change in the carbon export efficiency in PISCES-QUOTA, we estimate that fixed stoichiometry models may be underestimating 21st century cumulative ocean carbon uptake by 0.5-3.5% (2.0-15.1 PgC).

  4. Effects of ocean acidification on the physiological performance and carbon production of the Antarctic sea ice diatom Nitzschia sp. ICE-H.

    PubMed

    Qu, Chang-Feng; Liu, Fang-Ming; Zheng, Zhou; Wang, Yi-Bin; Li, Xue-Gang; Yuan, Hua-Mao; Li, Ning; An, Mei-Ling; Wang, Xi-Xi; He, Ying-Ying; Li, Lu-Lu; Miao, Jin-Lai

    2017-07-15

    Ocean acidification (OA) resulting from increasing atmospheric CO 2 strongly influences marine ecosystems, particularly in the polar ocean due to greater CO 2 solubility. Here, we grew the Antarctic sea ice diatom Nitzschia sp. ICE-H in a semicontinuous culture under low (~400ppm) and high (1000ppm) CO 2 levels. Elevated CO 2 resulted in a stimulated physiological response including increased growth rates, chlorophyll a contents, and nitrogen and phosphorus uptake rates. Furthermore, high CO 2 enhanced cellular particulate organic carbon production rates, indicating a greater shift from inorganic to organic carbon. However, the cultures grown in high CO 2 conditions exhibited a decrease in both extracellular and intracellular carbonic anhydrase activity, suggesting that the carbon concentrating mechanisms of Nitzschia sp. ICE-H may be suppressed by elevated CO 2 . Our results revealed that OA would be beneficial to the survival of this sea ice diatom strain, with broad implications for global carbon cycles in the future ocean. Copyright © 2017. Published by Elsevier Ltd.

  5. Adsorption of p-cresol on novel diatomite/carbon composites.

    PubMed

    Hadjar, H; Hamdi, B; Ania, C O

    2011-04-15

    Hybrid inorganic/organic adsorbents were synthesized using mixtures of diatomite and carbon charcoal as precursors, and explored for the removal of p-cresol from aqueous solution. The carbon/diatomite composites displayed a bimodal and interconnected porous structure which was partially inherited from both precursors. They display moderate surface areas (between 100 and 400 m(2)g(-1)) due to their large inorganic content (between 70 and 90 wt.%), since the diatomite is a non-porous material. Compared to activated carbons with a more developed porosity, p-cresol adsorption on the prepared carbon/diatomite composites was much faster, showing adsorption capacities similar to those of conventional adsorbents over a wide pH range. These results show a good affinity of p-cresol molecules towards the hybrid inorganic/organic composites, and demonstrate the suitability of these novel materials for the removal of aromatic (polar) molecules, despite their dominant inorganic character. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Audit of the global carbon budget: estimate errors and their impact on uptake uncertainty

    NASA Astrophysics Data System (ADS)

    Ballantyne, A. P.; Andres, R.; Houghton, R.; Stocker, B. D.; Wanninkhof, R.; Anderegg, W.; Cooper, L. A.; DeGrandpre, M.; Tans, P. P.; Miller, J. B.; Alden, C.; White, J. W. C.

    2015-04-01

    Over the last 5 decades monitoring systems have been developed to detect changes in the accumulation of carbon (C) in the atmosphere and ocean; however, our ability to detect changes in the behavior of the global C cycle is still hindered by measurement and estimate errors. Here we present a rigorous and flexible framework for assessing the temporal and spatial components of estimate errors and their impact on uncertainty in net C uptake by the biosphere. We present a novel approach for incorporating temporally correlated random error into the error structure of emission estimates. Based on this approach, we conclude that the 2σ uncertainties of the atmospheric growth rate have decreased from 1.2 Pg C yr-1 in the 1960s to 0.3 Pg C yr-1 in the 2000s due to an expansion of the atmospheric observation network. The 2σ uncertainties in fossil fuel emissions have increased from 0.3 Pg C yr-1 in the 1960s to almost 1.0 Pg C yr-1 during the 2000s due to differences in national reporting errors and differences in energy inventories. Lastly, while land use emissions have remained fairly constant, their errors still remain high and thus their global C uptake uncertainty is not trivial. Currently, the absolute errors in fossil fuel emissions rival the total emissions from land use, highlighting the extent to which fossil fuels dominate the global C budget. Because errors in the atmospheric growth rate have decreased faster than errors in total emissions have increased, a ~20% reduction in the overall uncertainty of net C global uptake has occurred. Given all the major sources of error in the global C budget that we could identify, we are 93% confident that terrestrial C uptake has increased and 97% confident that ocean C uptake has increased over the last 5 decades. Thus, it is clear that arguably one of the most vital ecosystem services currently provided by the biosphere is the continued removal of approximately half of atmospheric CO2 emissions from the atmosphere

  7. Audit of the global carbon budget: estimate errors and their impact on uptake uncertainty

    DOE PAGES

    Ballantyne, A. P.; Andres, R.; Houghton, R.; ...

    2015-04-30

    Over the last 5 decades monitoring systems have been developed to detect changes in the accumulation of carbon (C) in the atmosphere and ocean; however, our ability to detect changes in the behavior of the global C cycle is still hindered by measurement and estimate errors. Here we present a rigorous and flexible framework for assessing the temporal and spatial components of estimate errors and their impact on uncertainty in net C uptake by the biosphere. We present a novel approach for incorporating temporally correlated random error into the error structure of emission estimates. Based on this approach, we concludemore » that the 2σ uncertainties of the atmospheric growth rate have decreased from 1.2 Pg C yr ₋1 in the 1960s to 0.3 Pg C yr ₋1 in the 2000s due to an expansion of the atmospheric observation network. The 2σ uncertainties in fossil fuel emissions have increased from 0.3 Pg C yr ₋1 in the 1960s to almost 1.0 Pg C yr ₋1 during the 2000s due to differences in national reporting errors and differences in energy inventories. Lastly, while land use emissions have remained fairly constant, their errors still remain high and thus their global C uptake uncertainty is not trivial. Currently, the absolute errors in fossil fuel emissions rival the total emissions from land use, highlighting the extent to which fossil fuels dominate the global C budget. Because errors in the atmospheric growth rate have decreased faster than errors in total emissions have increased, a ~20% reduction in the overall uncertainty of net C global uptake has occurred. Given all the major sources of error in the global C budget that we could identify, we are 93% confident that terrestrial C uptake has increased and 97% confident that ocean C uptake has increased over the last 5 decades. Thus, it is clear that arguably one of the most vital ecosystem services currently provided by the biosphere is the continued removal of approximately half of atmospheric CO 2 emissions from

  8. Carbon and Nutrient Dynamics and Fluxes in the Northwest European Continental Shelf Sea

    NASA Astrophysics Data System (ADS)

    Humphreys, M. P.; Moore, M. M.; Achterberg, E. P.; Griffiths, A.; Smilenova, A.; Chowdhury, M. Z. H.; Kivimae, C.; Hartman, S. E.; Hopkins, J.; Woodward, M. S.

    2016-02-01

    Despite covering only about 5 % of the Earth's ocean surface area, shallow marginal seas support 15-20 % of global primary productivity, and are the key interface between the land and the open ocean. They are therefore of critical importance to marine biogeochemical cycles, and may have a significant role in ocean uptake and storage of anthropogenic carbon dioxide (CO2). However, their behaviour is significantly more complex than that of the open ocean, because of the greater heterogeneity of the underlying physical, chemical and biological processes acting upon them. Detailed case-studies of individual regions are therefore essential in order to accurately evaluate their net global influence. The Northwest European continental shelf, in particular the Celtic Sea, was the target of extensive hydrographic sampling from March 2014 to September 2015, as part of the UK Shelf Seas Biogeochemistry research programme (UK-SSB). Here, we use the UK-SSB carbonate chemistry and macronutrient measurements to describe the seasonal biogeochemical cycle in the Celtic Sea. The 100-200 m deep water column proceeds from vertically well mixed in winter to a strongly stratified two-layer structure over spring-summer. The associated seasonal cycle in near-surface biological activity removes dissolved inorganic carbon (DIC) and nutrients, some of which are then exported into the deeper layer. Calculating total inventories of the biogeochemical variables throughout the seasonal cycle, we determine seasonal net CO2 uptake and investigate whether non-Redfieldian macronutrient uptake and remineralisation processes occur. Combining these results with estimated water exchange across the shelf edge further allows us to quantify the strength of the `shelf pump' sink for atmospheric (and anthropogenic) CO2.

  9. Nonlinear Interactions between Climate and Atmospheric Carbon Dioxide Drivers of Terrestrial and Marine Carbon Cycle Changes

    NASA Astrophysics Data System (ADS)

    Hoffman, F. M.; Randerson, J. T.; Moore, J. K.; Goulden, M.; Fu, W.; Koven, C.; Swann, A. L. S.; Mahowald, N. M.; Lindsay, K. T.; Munoz, E.

    2017-12-01

    Quantifying interactions between global biogeochemical cycles and the Earth system is important for predicting future atmospheric composition and informing energy policy. We applied a feedback analysis framework to three sets of Historical (1850-2005), Representative Concentration Pathway 8.5 (2006-2100), and its extension (2101-2300) simulations from the Community Earth System Model version 1.0 (CESM1(BGC)) to quantify drivers of terrestrial and ocean responses of carbon uptake. In the biogeochemically coupled simulation (BGC), the effects of CO2 fertilization and nitrogen deposition influenced marine and terrestrial carbon cycling. In the radiatively coupled simulation (RAD), the effects of rising temperature and circulation changes due to radiative forcing from CO2, other greenhouse gases, and aerosols were the sole drivers of carbon cycle changes. In the third, fully coupled simulation (FC), both the biogeochemical and radiative coupling effects acted simultaneously. We found that climate-carbon sensitivities derived from RAD simulations produced a net ocean carbon storage climate sensitivity that was weaker and a net land carbon storage climate sensitivity that was stronger than those diagnosed from the FC and BGC simulations. For the ocean, this nonlinearity was associated with warming-induced weakening of ocean circulation and mixing that limited exchange of dissolved inorganic carbon between surface and deeper water masses. For the land, this nonlinearity was associated with strong gains in gross primary production in the FC simulation, driven by enhancements in the hydrological cycle and increased nutrient availability. We developed and applied a nonlinearity metric to rank model responses and driver variables. The climate-carbon cycle feedback gain at 2300 was 42% higher when estimated from climate-carbon sensitivities derived from the difference between FC and BGC than when derived from RAD. We re-analyzed other CMIP5 model results to quantify the

  10. Effects of inorganic carbon on the nitrous oxide emissions and microbial diversity of an anaerobic ammonia oxidation reactor.

    PubMed

    Zhang, Wenjie; Wang, Dunqiu; Jin, Yue

    2018-02-01

    Inorganic carbon (IC) is important for anaerobic ammonium oxidation (anammox). In this study, the effects of the IC concentration on N 2 O emissions and microbial diversity in an anammox reactor were investigated. N 2 O emissions were positively correlated with IC concentrations, and IC concentrations in the range of 55-130 mg/L were optimal, considering the nitrogen removal rate and N 2 O emissions. High IC concentrations resulted in the formation of CaCO 3 on the surface of anammox granules, which impacted the diffusion conditions of the substrate. Microbial community analysis indicated that high IC concentrations decreased the populations of specific bacteria, such as Achromobacter spanius strain YJART-7, Achromobacter xylosoxidans strain IHB B 6801, and Denitratisoma oestradiolicum clone 20b_15. D. oestradiolicum clone 20b_15 appeared to be the key contributor to N 2 O emissions. High N 2 O emissions may result from changes in organic carbon sources, which lead to denitrification by D. oestradiolicum clone 20b_15. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Effect of inorganic nitrogenous fertilizer on productivity of recently reclaimed saline sodic soils with and without biofertilizer.

    PubMed

    Mehdi, S M; Sarfraz, M; Shabbir, G; Abbas, G

    2007-07-15

    Saline sodic soils after reclamation become infertile due to leaching of most of the nutrients along with salts from the rooting medium. Microbes can play a vital role in the productivity improvement of such soils. In this study a saline sodic field having EC, 6.5 dS m(-1), pH, 9.1 and gypsum requirement (GR) 3.5 tons acre(-1) was reclaimed by applying gypsum at the rate of 100% GR. Rice and wheat crops were transplanted/sown for three consecutive years. Inorganic nitrogenous fertilizer was used with and without biofertilizers i.e., Biopower (Azospirillum) for rice and diazotroph inoculums for wheat. Nitrogen was applied at the rate of 0, 75% of recommended dose (RD), RD, 125% of RD and 150% of RD. Recommended dose of P without K was applied to all the plots. Biopower significantly improved Paddy and straw yield of rice over inorganic nitrogenous fertilizer. In case of wheat diazotroph inoculum improved grain and straw yield significantly over inorganic nitrogenous fertilizer. Among N fertilizer rates, RD + 25% additional N fertilizer was found to be the best dose for rice and wheat production in recently reclaimed soils. Nitrogen concentration and its uptake by paddy, grain and straw were also increased by biopower and diazotroph inoculum over inorganic nitrogenous fertilizer. Among N fertilizer rates, RD + 25% additional N fertilizer was found to be the best dose for nitrogen concentration and its uptake by paddy, grain and straw. Total soil N, available P and extractable K were increased while salinity/sodicity parameters were decreased with the passage of time. The productivity of the soil was improved more by biofertilizers over inorganic N fertilizers.

  12. Simulated Impact of Glacial Runoff on CO2 Uptake in the Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Pilcher, Darren J.; Siedlecki, Samantha A.; Hermann, Albert J.; Coyle, Kenneth O.; Mathis, Jeremy T.; Evans, Wiley

    2018-01-01

    The Gulf of Alaska (GOA) receives substantial summer freshwater runoff from glacial meltwater. The alkalinity of this runoff is highly dependent on the glacial source and can modify the coastal carbon cycle. We use a regional ocean biogeochemical model to simulate CO2 uptake in the GOA under different alkalinity-loading scenarios. The GOA is identified as a current net sink of carbon, though low-alkalinity tidewater glacial runoff suppresses summer coastal carbon uptake. Our model shows that increasing the alkalinity generates an increase in annual CO2 uptake of 1.9-2.7 TgC/yr. This transition is comparable to a projected change in glacial runoff composition (i.e., from tidewater to land-terminating) due to continued climate warming. Our results demonstrate an important local carbon-climate feedback that can significantly increase coastal carbon uptake via enhanced air-sea exchange, with potential implications to the coastal ecosystems in glaciated areas around the world.

  13. Removal of inorganic mercury from aquatic environments by multi-walled carbon nanotubes.

    PubMed

    Yaghmaeian, Kamyar; Khosravi Mashizi, Reza; Nasseri, Simin; Mahvi, Amir Hossein; Alimohammadi, Mahmood; Nazmara, Shahrokh

    2015-01-01

    Mercury is considered as a toxic heavy metal in aquatic environments due to accumulation in bodies of living organisms. Exposure to mercury may lead to different toxic effects in humans including damages to kidneys and nervous system. Multi-walled carbon nanotubes (MWCNTs) were selected as sorbent to remove mercury from aqueous solution using batch technique. ICP instrument was used to determine the amount of mercury in solution. Moreover, pH, contact time and initial concentration of mercury were studied to determine the influence of these parameters on the adsorption conditions. Results indicate that the adsorption strongly depended on pH and the best pH for adsorption is about 7. The rate of adsorption process initially was rapid but it was gradually reduced with increasing of contact time and reached the equilibrium after 120 min. In addition, more than 85 % of initial concentration of 0.1 mg/l was removed at 0.5 g/l concentration of sorbent and contact time of 120 min. Meanwhile, the adsorption process followed the pseudo second-order model and the adsorption isotherms could be described by both the Freundlich and the Langmuir models. This study showed that MWCNTs can effectively remove inorganic mercury from aqueous solutions as adsorbent.

  14. Inter-annual variation of carbon uptake by a plantation oak woodland in south-eastern England

    NASA Astrophysics Data System (ADS)

    Wilkinson, M.; Eaton, E. L.; Broadmeadow, M. S. J.; Morison, J. I. L.

    2012-07-01

    The carbon balance of an 80 yr old deciduous oak plantation in the temperate oceanic climate of the south-east of Britain was measured by eddy covariance over 12 yr (1999-2010). The mean annual net ecosystem productivity (NEP) was 486 g C m-2 y-1 (95% CI of ±73 g C m-2 y-1), and this was partitioned into a Gross Primary Productivity (GPP) of 2034 ± 145 g C m-2 y-1, over a 165 (±6) day growing season, and an annual loss of carbon through respiration and decomposition (ecosystem respiration, Reco) of 1548 ± 122 g C m-2 y-1. The interannual variation of NEP was large (coefficient of variation (CV) 23%), although the variation for GPP and Reco was smaller (12%) and the ratio of Reco/GPP was relatively constant (0.76 ± 0.02 CI). Some anomalies in the annual patterns of the carbon balance could be linked to particular combinations of anomalous weather events, such as high summer air temperature and low soil moisture content. The Europe-wide heat-wave and drought of 2003 had little effect on the C balance of this woodland on a surface water gley soil. Annual variation in precipitation (CV 18%) was not a main factor in the variation in NEP. The inter-annual variation in estimated intercepted radiation only accounted for ~ 47% of the variation in GPP, although a significant relationship (p<0.001) was found between peak leaf area index and annual GPP which in turn played an important role in modifying the efficiency with which incident radiation was used in net CO2 uptake. Whilst the spring start and late autumn end of the net CO2 uptake period varied substantially (range of 24 and 27 days, respectively), annual GPP was not related to growing season length. Severe outbreaks of defoliating moth caterpillars, mostly Tortrix viridana L. and Operophtera brumata L., caused considerable damage to the forest canopy in 2009 and 2010, resulting in reduced GPP in these years.

  15. Interannual Variation in Carbon Sequestration Depends Mainly on the Carbon Uptake Period in Two Croplands on the North China Plain

    PubMed Central

    Bao, Xueyan; Wen, Xuefa; Sun, Xiaomin; Zhao, Fenghua; Wang, Yuying

    2014-01-01

    Interannual variation in plant phenology can lead to major modifications in the interannual variation of net ecosystem production (NEP) and net biome production (NBP) as a result of recent climate change in croplands. Continuous measurements of carbon flux using the eddy covariance technique were conducted in two winter wheat and summer maize double-cropped croplands during 2003–2012 in Yucheng and during 2007–2012 in Luancheng on the North China Plain. Our results showed that the difference between the NEP and the NBP, i.e., the crop economic yield, was conservative even though the NEP and the NBP for both sites exhibited marked fluctuations during the years of observation. A significant and positive relationship was found between the annual carbon uptake period (CUP) and the NEP as well as the NBP. The NEP and the NBP would increase by 14.8±5.2 and 14.7±6.6 g C m−2 yr−1, respectively, if one CUP-day was extended. A positive relationship also existed between the CUP and the NEP as well as the NBP for winter wheat and summer maize, respectively. The annual air temperature, through its negative effect on the start date of the CUP, determined the length of the CUP. The spring temperature was the main indirect factor controlling the annual carbon sequestration when a one-season crop (winter wheat) was considered. Thus, global warming can be expected to extend the length of the CUP and thus increase carbon sequestration in croplands. PMID:25313713

  16. Biogeochemical generation of dissolved inorganic carbon and nitrogen in the North Branch of inner Changjiang Estuary in a dry season

    NASA Astrophysics Data System (ADS)

    Zhai, Wei-Dong; Yan, Xiu-Li; Qi, Di

    2017-10-01

    We investigated the surface water carbonate system, nutrients, and relevant hydrochemical parameters in the inner Changjiang (Yangtze River) Estuary in early spring 2009 and 2010. The two surveys were carried out shortly after spring-tide days, and covered both the channel-like South Branch and the freshwater-blocked North Branch. In the North Branch, with a water residence time of approximately one month, we detected remarkable partial pressures of CO2 (pCO2) of 930-1518 μatm with a salinity range of 4.5-17.4, which were substantially higher than the South Branch pCO2 values of 700-1100 μatm at salinities of less than 0.88. The North Branch pCO2 distribution pattern is unique compared with many other estuaries where aquatic pCO2 normally declines with salinity increase. Furthermore, the biogeochemical additions of ammonium (7.4-65.7 μmol kg-1) and alkalinity (196-695 μmol kg-1) were identified in salinities between 4 and 16 in the North Branch. Based on field data analyses and simplified stoichiometric equations, we suggest that the relatively high North Branch pCO2 values and estuarine additions of dissolved inorganic nitrogen/carbon in the mid-salinity area were strongly associated with each other. These signals were primarily controlled by biogeochemical processes in the North Branch, combining biogenic organic matter decomposition (i.e. respiration), ammonia oxidation, CaCO3 dissolution, and CO2 degassing. In the upper reach of the South Branch, notable salinity values of 0.20-0.88 were detected, indicating saltwater spillover from the North Branch. These spillover waters had minor contributions (1.5-6.9%) to the springtime nutrient, dissolved inorganic carbon, and alkalinity export fluxes from Changjiang to the adjacent East China Sea. This is the first attempt to understand the biogeochemical controls of the unique pCO2 distributions in the North Branch, and to evaluate the effects of saltwater spillover from the North Branch on dry-season export fluxes

  17. Carbonate counter pump stimulated by natural iron fertilization in the Polar Frontal Zone

    NASA Astrophysics Data System (ADS)

    Salter, Ian; Schiebel, Ralf; Ziveri, Patrizia; Movellan, Aurore; Lampitt, Richard; Wolff, George A.

    2014-12-01

    The production of organic carbon in the ocean's surface and its subsequent downward export transfers carbon dioxide to the deep ocean. This CO2 drawdown is countered by the biological precipitation of carbonate, followed by sinking of particulate inorganic carbon, which is a source of carbon dioxide to the surface ocean, and hence the atmosphere over 100-1,000 year timescales. The net transfer of CO2 to the deep ocean is therefore dependent on the relative amount of organic and inorganic carbon in sinking particles. In the Southern Ocean, iron fertilization has been shown to increase the export of organic carbon, but it is unclear to what degree this effect is compensated by the export of inorganic carbon. Here we assess the composition of sinking particles collected from sediment traps located in the Polar Frontal Zone of the Southern Ocean. We find that in high-nutrient, low-chlorophyll regions that are characterized by naturally high iron concentrations, fluxes of both organic and inorganic carbon are higher than in regions with no iron fertilization. However, the excess flux of inorganic carbon is greater than that of organic carbon. We estimate that the production and flux of carbonate in naturally iron-fertilized waters reduces the overall amount of CO2 transferred to the deep ocean by 6-32%, compared to 1-4% at the non-fertilized site. We suggest that an increased export of organic carbon, stimulated by iron availability in the glacial sub-Antarctic oceans, may have been accompanied by a strengthened carbonate counter pump.

  18. Cyclic variations in nitrogen uptake rate in soybean plants: uptake during reproductive growth

    NASA Technical Reports Server (NTRS)

    Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

    1990-01-01

    Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic culture was measured daily during a 63 d period of reproductive development between the first florally inductive photoperiod and [unknown word] seed growth. Removal of NO3- from a replenished solution containing 1.0 mol m-3 NO3- was determined by ion chromatography. Uptake of NO3- continued throughout reproductive development. The net uptake rate of NO3- cycled between maxima and minima with a periodicity of oscillation of 3 to 7 d during the floral stage and about 6 d during the fruiting stage. Coupled with increasing concentrations of carbon and C : N ratios in tissues, the oscillations in net uptake rates of NO3- are evidence that the demand for carbohydrate by reproductive organs is contingent on the availability of nitrogen in the shoot pool rather than that the demand for nitrogen follows the flux of carbohydrate into reproductive tissues.

  19. Submicron magnetite grains and carbon compounds in Martian meteorite ALH84001: inorganic, abiotic formation by shock and thermal metamorphism.

    PubMed

    Treiman, Allan H

    2003-01-01

    Purported biogenic features of the ALH84001 Martian meteorite (the carbonate globules, their submicron magnetite grains, and organic matter) have reasonable inorganic origins, and a comprehensive hypothesis is offered here. The carbonate globules were deposited from hydrothermal water, without biological mediation. Thereafter, ALH84001 was affected by an impact shock event, which raised its temperature nearly instantaneously to 500-700K, and induced iron-rich carbonate in the globules to decompose to magnetite and other minerals. The rapidity of the temperature increase caused magnetite grains to nucleate in abundance; hence individual crystals were very small. Nucleation and growth of magnetite crystals were fastest along edges and faces of the precursor carbonate grains, forcing the magnetite grains to be platy or elongated, including the "truncated hexa-octahedra" shape. ALH84001 had formed at some depth within Mars where the lithostatic pressure was significantly above that of Mars' surface. Also, because the rock was at depth, the impact heat dissipated slowly. During this interval, magnetite crystals approached chemical equilibria with surrounding minerals and gas. Their composition, nearly pure Fe(3)O(4), reflects those of equilibria; elements that substitute into magnetite are either absent from iron-rich carbonate (e.g., Ti, Al, Cr), or partitioned into other minerals during magnetite formation (Mg, Mn). Many microstructural imperfections in the magnetite grains would have annealed out as the rock cooled. In this post-shock thermal regime, carbon-bearing gas from the decomposition of iron carbonates reacted with water in the rock (or from its surroundings) to produce organic matter via Fischer-Tropschlike reactions. Formation of such organic compounds like polycyclic aromatic hydrocarbons would have been catalyzed by the magnetite (formation of graphite, the thermochemically stable phase, would be kinetically hindered).

  20. Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 1. Sulfate from confining beds as an oxidant in microbial CO2 production

    USGS Publications Warehouse

    Chapelle, F.H.; McMahon, P.B.

    1991-01-01

    A primary source of dissolved inorganic carbon (DIC) in the Black Creek aquifer of South Carolina is carbon dioxide produced by microbially mediated oxidation of sedimentary organic matter. Groundwater chemistry data indicate, however, that the available mass of inorganic electron acceptors (oxygen, Fe(III), and sulfate) and observed methane production is inadequate to account for observed CO2 production. Although sulfate concentrations are low (approximately 0.05-0.10 mM) in aquifer water throughout the flow system, sulfate concentrations are greater in confining-bed pore water (0.4-20 mM). The distribution of culturable sulfate-reducing bacteria in these sediments suggests that this concentration gradient is maintained by greater sulfate-reducing activity in sands than in clays. Calculations based on Fick's Law indicate that possible rates of sulfate diffusion to aquifer sediments are sufficient to explain observed rates of CO2 production (about 10-5 mmoll-1 year-1), thus eliminating the apparent electron-acceptor deficit. Furthermore, concentrations of dissolved hydrogen in aquifer water are in the range characteristic of sulfate reduction (2-6 nM), which provides independent evidence that sulfate reduction is the predominant terminal electron-accepting process in this system. The observed accumulation of pyrite- and calcite-cemented sandstones at sand-clay interfaces is direct physical evidence that these processes have been continuing over the history of these sediments. ?? 1991.

  1. A Restricted Boltzman Neural Net to Infer Carbon Uptake from OCO-2 Satellite Data

    NASA Astrophysics Data System (ADS)

    Halem, M.; Dorband, J. E.; Radov, A.; Barr-Dallas, M.; Gentine, P.

    2015-12-01

    For several decades, scientists have been using satellite observations to infer climate budgets of terrestrial carbon uptake employing inverse methods in conjunction with ecosystem models and coupled global climate models. This is an extremely important Big Data calculation today since the net annual photosynthetic carbon uptake changes annually over land and removes on average ~20% of the emissions from human contributions to atmospheric loading of CO2 from fossil fuels. Unfortunately, such calculations have large uncertainties validated with in-situ networks of measuring stations across the globe. One difficulty in using satellite data for these budget calculations is that the models need to assimilate surface fluxes of CO2 as well as soil moisture, vegatation cover and the eddy covariance of latent and sensible heat to calculate the carbon fixed in the soil while satellite spectral observations only provide near surface concentrations of CO2. In July 2014, NASA successfully launched OCO-2 which provides 3km surface measurements of CO2 over land and oceans. We have collected nearly one year of Level 2 XCO2 data from the OCO-2 satellite for 3 sites of ~200 km2 at equatorial, temperate and high latitudes. Each selected site was part of the Fluxnet or ARM system with tower stations for measuring and collecting CO2 fluxes on an hourly basis, in addition to eddy transports of the other parameters. We are also planning to acquire the 4km NDVI products from MODIS and registering the data to the 3km XCO2 footprints for the three sites. We have implemented a restricted Boltzman machine on the quantum annealing D-Wave computer, a novel deep learning neural net, to be used for training with station data to infer CO2 fluxes from collocated XCO2, MODIS vegetative land cover and MERRA reanalysis surface exchange products. We will present performance assessments of the D-Wave Boltzman machine for generating XCO2 fluxes from the OCO-2 satellite observations for the 3 sites by

  2. Inorganic fullerenes and nanotubes: Wealth of materials and morphologies

    NASA Astrophysics Data System (ADS)

    Bar-Sadan, M.; Kaplan-Ashiri, I.; Tenne, R.

    2007-10-01

    It is already well established today that numerous materials form closed-cage structures, of which carbon fullerenes and nanotubes are a special case [1]. Inorganic fullerene-like nanoparticles (designated IF) and inorganic nanotubes (INT) have been produced by different routes and experimental techniques, achieving persistent growth of a variety of materials and structural wealth within them. The research in this area has focused on synthesizing new IF and INT materials and understanding their different properties as well as scaling up the synthetic process in order to make it suitable for industrial applications. In this review, the main synthetic procedures to obtain inorganic fullerene-like nanoparticles and nanotubes will be discussed alongside with the different mechanisms that affect the morphology of the final product. The main differences between the morphologies will be presented. Some general considerations relating the properties of the parent compound with the morphology of the product will be mentioned.

  3. Atmospheric CO2 Observations Reveal Strong Correlation Between Regional Net Biospheric Carbon Uptake and Solar-Induced Chlorophyll Fluorescence

    NASA Astrophysics Data System (ADS)

    Shiga, Yoichi P.; Tadić, Jovan M.; Qiu, Xuemei; Yadav, Vineet; Andrews, Arlyn E.; Berry, Joseph A.; Michalak, Anna M.

    2018-01-01

    Recent studies have shown the promise of remotely sensed solar-induced chlorophyll fluorescence (SIF) in informing terrestrial carbon exchange, but analyses have been limited to either plot level ( 1 km2) or hemispheric/global ( 108 km2) scales due to the lack of a direct measure of carbon exchange at intermediate scales. Here we use a network of atmospheric CO2 observations over North America to explore the value of SIF for informing net ecosystem exchange (NEE) at regional scales. We find that SIF explains space-time NEE patterns at regional ( 100 km2) scales better than a variety of other vegetation and climate indicators. We further show that incorporating SIF into an atmospheric inversion leads to a spatial redistribution of NEE estimates over North America, with more uptake attributed to agricultural regions and less to needleleaf forests. Our results highlight the synergy of ground-based and spaceborne carbon cycle observations.

  4. Hazardous wastes in aquatic environments: Biological uptake and metabolism studies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Barber, J.; Apblett, A.; Ensley, H.

    1996-05-02

    The projects discussed in this article include the following: the uptake, accumulation, metabolism, toxicity and physiological effects of various environmentally-important contaminants, inorganic and organic, in several wetland species that are interrelated through food webs; and investigation of the potential for developing and linking chemical and biological methods of remediation so as to encapsulate bioaccummulated ions in stable wasteforms such as ceramics and/or zeolites. 24 refs.

  5. EFFECT OF CHELATING AGENTS ON UPTAKE OF Ca$sup 45$ AND Sr$sup 85$ BY DEFATTED BONE IN VITRO

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Samachson, J.; Lederer, H.

    The presence of chelating agents in buffered solutions affected the relative uptake of Ca/sup 45/ and Sr/sup 85/ by defatted bone powder. Strong chelating agents, like ethylenediaminetetraacetic acid and cyclohexanediaminetetraacetic acid, decreased the ratio of Ca/sup 45//Sr/sup 85/ uptake considerably in presence of Ca, Ca plus Sr, or Sr carrier. Citrate and adenosinetriphosphate had similar but weaker effects. No effect was shown by glucose, lactate, gluconate, bicarbonate, bicarbonate plus phosphate, glutamate, aspartate, borate, glycerophosphate, lysine or glutathione. Those compeunds which showed no effect had stability constants for Ca of less than 3. Strong chelating agents also decreased the relative amountmore » of Sr/sup 85/ removed from defatted bone powder by exchange. Results indicate that natural chelating agents may be partly responsible for the low Ca/sup 45//Sr/sup 85/ uptake ratio by bone from serum compared with uptake from synthetic inorganic solutions and emphasize the difficulty of removing be partly responsible for the low Ca/sup 45//Sr/sup 85/ uptske ratio by bone from serum compared with uptake from synthetic inorganic solutions and emphasize the difficulty of removing Sr/sup 35/ from bone with chelating agents now available. (auth)« less

  6. Fire-induced Carbon Emissions and Regrowth Uptake in Western U.S. Forests: Documenting Variation Across Forest Types, Fire Severity, and Climate Regions

    NASA Technical Reports Server (NTRS)

    Ghimire, Bardan; Williams, Christopher A.; Collatz, George James; Vanderhoof, Melanie

    2012-01-01

    The forest area in the western United States that burns annually is increasing with warmer temperatures, more frequent droughts, and higher fuel densities. Studies that examine fire effects for regional carbon balances have tended to either focus on individual fires as examples or adopt generalizations without considering how forest type, fire severity, and regional climate influence carbon legacies. This study provides a more detailed characterization of fire effects and quantifies the full carbon impacts in relation to direct emissions, slow release of fire-killed biomass, and net carbon uptake from forest regrowth. We find important variations in fire-induced mortality and combustion across carbon pools (leaf, live wood, dead wood, litter, and duff) and across low- to high-severity classes. This corresponds to fire-induced direct emissions from 1984 to 2008 averaging 4 TgC/yr and biomass killed averaging 10.5 TgC/yr, with average burn area of 2723 sq km/yr across the western United States. These direct emission and biomass killed rates were 1.4 and 3.7 times higher, respectively, for high-severity fires than those for low-severity fires. The results show that forest regrowth varies greatly by forest type and with severity and that these factors impose a sustained carbon uptake legacy. The western U.S. fires between 1984 and 2008 imposed a net source of 12.3 TgC/yr in 2008, accounting for both direct fire emissions (9.5 TgC/yr) and heterotrophic decomposition of fire-killed biomass (6.1 TgC yr1) as well as contemporary regrowth sinks (3.3 TgC/yr). A sizeable trend exists toward increasing emissions as a larger area burns annually.

  7. Edge effects enhance carbon uptake and its vulnerability to climate change in temperate broadleaf forests

    PubMed Central

    Reinmann, Andrew B.; Hutyra, Lucy R.

    2017-01-01

    Forest fragmentation is a ubiquitous, ongoing global phenomenon with profound impacts on the growing conditions of the world’s remaining forest. The temperate broadleaf forest makes a large contribution to the global terrestrial carbon sink but is also the most heavily fragmented forest biome in the world. We use field measurements and geospatial analyses to characterize carbon dynamics in temperate broadleaf forest fragments. We show that forest growth and biomass increase by 89 ± 17% and 64 ± 12%, respectively, from the forest interior to edge, but ecosystem edge enhancements are not currently captured by models or approaches to quantifying regional C balance. To the extent that the findings from our research represent the forest of southern New England in the United States, we provide a preliminary estimate that edge growth enhancement could increase estimates of the region’s carbon uptake and storage by 13 ± 3% and 10 ± 1%, respectively. However, we also find that forest growth near the edge declines three times faster than that in the interior in response to heat stress during the growing season. Using climate projections, we show that future heat stress could reduce the forest edge growth enhancement by one-third by the end of the century. These findings contrast studies of edge effects in the world’s other major forest biomes and indicate that the strength of the temperate broadleaf forest carbon sink and its capacity to mitigate anthropogenic carbon emissions may be stronger, but also more sensitive to climate change than previous estimates suggest. PMID:27994137

  8. Edge effects enhance carbon uptake and its vulnerability to climate change in temperate broadleaf forests.

    PubMed

    Reinmann, Andrew B; Hutyra, Lucy R

    2017-01-03

    Forest fragmentation is a ubiquitous, ongoing global phenomenon with profound impacts on the growing conditions of the world's remaining forest. The temperate broadleaf forest makes a large contribution to the global terrestrial carbon sink but is also the most heavily fragmented forest biome in the world. We use field measurements and geospatial analyses to characterize carbon dynamics in temperate broadleaf forest fragments. We show that forest growth and biomass increase by 89 ± 17% and 64 ± 12%, respectively, from the forest interior to edge, but ecosystem edge enhancements are not currently captured by models or approaches to quantifying regional C balance. To the extent that the findings from our research represent the forest of southern New England in the United States, we provide a preliminary estimate that edge growth enhancement could increase estimates of the region's carbon uptake and storage by 13 ± 3% and 10 ± 1%, respectively. However, we also find that forest growth near the edge declines three times faster than that in the interior in response to heat stress during the growing season. Using climate projections, we show that future heat stress could reduce the forest edge growth enhancement by one-third by the end of the century. These findings contrast studies of edge effects in the world's other major forest biomes and indicate that the strength of the temperate broadleaf forest carbon sink and its capacity to mitigate anthropogenic carbon emissions may be stronger, but also more sensitive to climate change than previous estimates suggest.

  9. Differential Assimilation of Inorganic Carbon and Leucine by Prochlorococcus in the Oligotrophic North Pacific Subtropical Gyre

    PubMed Central

    Björkman, Karin M.; Church, Matthew J.; Doggett, Joseph K.; Karl, David M.

    2015-01-01

    The light effect on photoheterotrophic processes in Prochlorococcus, and primary and bacterial productivity in the oligotrophic North Pacific Subtropical Gyre was investigated using 14C-bicarbonate and 3H-leucine. Light and dark incubation experiments were conducted in situ throughout the euphotic zone (0–175 m) on nine expeditions to Station ALOHA over a 3-year period. Photosynthetrons were also used to elucidate rate responses in leucine and inorganic carbon assimilation as a function of light intensity. Taxonomic group and cell-specific rates were assessed using flow cytometric sorting. The light:dark assimilation rate ratios of leucine in the top 150 m were ∼7:1 for Prochlorococcus, whereas the light:dark ratios for the non-pigmented bacteria (NPB) were not significant different from 1:1. Prochlorococcus assimilated leucine in the dark at per cell rates similar to the NPB, with a contribution to the total community bacterial production, integrated over the euphotic zone, of approximately 20% in the dark and 60% in the light. Depth-resolved primary productivity and leucine incorporation showed that the ratio of Prochlorococcus leucine:primary production peaked at 100 m then declined steeply below the deep chlorophyll maximum (DCM). The photosynthetron experiments revealed that, for Prochlorococcus at the DCM, the saturating irradiance (Ek) for leucine incorporation was reached at approximately half the light intensity required for light saturation of 14C-bicarbonate assimilation. Additionally, high and low red fluorescing Prochlorococcus populations (HRF and LRF), co-occurring at the DCM, had similar Ek values for their respective substrates, however, maximum assimilation rates, for both leucine and inorganic carbon, were two times greater for HRF cells. Our results show that Prochlorococcus contributes significantly to bacterial production estimates using 3H-leucine, whether or not the incubations are conducted in the dark or light, and this should be

  10. Impact of Glycerol as Carbon Source onto Specific Sugar and Inducer Uptake Rates and Inclusion Body Productivity in E. coli BL21(DE3).

    PubMed

    Kopp, Julian; Slouka, Christoph; Ulonska, Sophia; Kager, Julian; Fricke, Jens; Spadiut, Oliver; Herwig, Christoph

    2017-12-21

    The Gram-negative bacterium E. coli is the host of choice for a multitude of used recombinant proteins. Generally, cultivation is easy, media are cheap, and a high product titer can be obtained. However, harsh induction procedures using isopropyl β-d-1 thiogalactopyranoside as inducer are often referred to cause stress reactions, leading to a phenomenon known as "metabolic" or "product burden". These high expressions of recombinant proteins mainly result in decreased growth rates and cell lysis at elevated induction times. Therefore, approaches tend to use "soft" or "tunable" induction with lactose and reduce the stress level of the production host. The usage of glucose as energy source in combination with lactose as induction reagent causes catabolite repression effects on lactose uptake kinetics and as a consequence reduced product titer. Glycerol-as an alternative carbon source-is already known to have positive impact on product formation when coupled with glucose and lactose in auto-induction systems, and has been referred to show no signs of repression when cultivated with lactose concomitantly. In recent research activities, the impact of different products on the lactose uptake using glucose as carbon source was highlighted, and a mechanistic model for glucose-lactose induction systems showed correlations between specific substrate uptake rate for glucose or glycerol (q s,C ) and the maximum specific lactose uptake rate (q s,lac,max ). In this study, we investigated the mechanistic of glycerol uptake when using the inducer lactose. We were able to show that a product-producing strain has significantly higher inducer uptake rates when being compared to a non-producer strain. Additionally, it was shown that glycerol has beneficial effects on viability of cells and on productivity of the recombinant protein compared to glucose.

  11. The mitigating effect of calcification-dependent of utilization of inorganic carbon of Chara vulgaris Linn on NH4-N toxicity.

    PubMed

    Wang, Heyun; Ni, Leyi; Xie, Ping

    2013-09-01

    Increased ammonium (NH4-N) concentrations in water bodies have been reported to adversely affect the dominant species of submersed vegetation in meso-eutrophic waters worldwide. However calcareous plants were lowly sensitive to NH4-N toxicity. In order to make clear the function of calcification in the tolerance of calcareous plants to NH4-N stress, we studied the effects of increased HCO3(-) and additional NH4-N on calcification and utilization of dissolve inorganic carbon (DIC) in Chara vulgaris Linn in a 7-d sub-acute experiment (light:dark 12:12h) carried out in an open experimental system in lab. Results revealed that calcification was dependent of utilization of dissolve inorganic carbon. Additional HCO3(-) significantly decreased the increase of pH while additional NH4-N did not. And additional HCO3(-) significantly improved calcification while NH4-N did in versus in relation to the variation of DIC concentration. However, addition of both HCO3(-) and NH4-N increased utilization of DIC. This resulted in calcification to utilization of DIC ratio decreased under additional NH4-N condition while increased under additional HCO3(-) conditions in response to the variation of solution pH. In the present study, external HCO3(-) decreased the increase of solution pH by increasing calcification, which correspondingly mitigated the toxic effect of high NH4-N. And we argue that the mitigating effect of increased HCO3(-) on NH4-N toxicity is dependent of plant calcification, and it is a positive feedback mechanism, potentially leading to the dominance of calcareous plants in meso-eutrophic water bodies. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Sustaining nutrient supply and carbon export in a seasonally-stratifying shelf sea through inconsistent production and remineralisation stoichiometry

    NASA Astrophysics Data System (ADS)

    Humphreys, Matthew; Moore, Mark; Achterberg, Eric; Chowdhury, Mohammed; Griffiths, Alex; Hartman, Susan; Hopkins, Joanne; Hull, Tom; Kivimäe, Caroline; Sivyer, Dave; Smilenova, Angelina; Wihsgott, Juliane; Woodward, Malcolm

    2017-04-01

    Continental shelf seas support 15-20% of global primary productivity despite covering only about 5% of the Earth's ocean surface area. As a result, they may have a significant role in oceanic uptake and storage of carbon dioxide (CO2) from the atmosphere, through the 'continental shelf pump' mechanism. The northwest European continental shelf, in particular the Celtic Sea (50°N 8°W), was the target of extensive biogeochemical sampling from March 2014 to September 2015, as part of the UK Shelf Sea Biogeochemistry research programme (UK-SSB). Here, we use the UK-SSB carbonate chemistry and macronutrient measurements to investigate the biogeochemical seasonality in the temperate, seasonally-stratifying Celtic Sea. During the spring-summer, near-surface biological activity removed dissolved inorganic carbon and nutrients, some of which were then exported into the deeper layer. We calculated vertical inventories of these variables throughout 1.5 seasonal cycles and attempted to correct these for air-sea CO2 exchange, advection and denitrification, thus isolating the combined effect of net community production and remineralisation on the inorganic macronutrient inventories, and revealing fluctuating deviations from Redfield stoichiometry. Here, we discuss the capacity of these stoichiometric inconsistencies to sustain the Celtic Sea nutrient supply, and thus examine whether an effective continental shelf pump for CO2 could operate in this region.

  13. Asphalt-derived high surface area activated porous carbons for carbon dioxide capture.

    PubMed

    Jalilov, Almaz S; Ruan, Gedeng; Hwang, Chih-Chau; Schipper, Desmond E; Tour, Josiah J; Li, Yilun; Fei, Huilong; Samuel, Errol L G; Tour, James M

    2015-01-21

    Research activity toward the development of new sorbents for carbon dioxide (CO2) capture have been increasing quickly. Despite the variety of existing materials with high surface areas and high CO2 uptake performances, the cost of the materials remains a dominant factor in slowing their industrial applications. Here we report preparation and CO2 uptake performance of microporous carbon materials synthesized from asphalt, a very inexpensive carbon source. Carbonization of asphalt with potassium hydroxide (KOH) at high temperatures (>600 °C) yields porous carbon materials (A-PC) with high surface areas of up to 2780 m(2) g(-1) and high CO2 uptake performance of 21 mmol g(-1) or 93 wt % at 30 bar and 25 °C. Furthermore, nitrogen doping and reduction with hydrogen yields active N-doped materials (A-NPC and A-rNPC) containing up to 9.3% nitrogen, making them nucleophilic porous carbons with further increase in the Brunauer-Emmett-Teller (BET) surface areas up to 2860 m(2) g(-1) for A-NPC and CO2 uptake to 26 mmol g(-1) or 114 wt % at 30 bar and 25 °C for A-rNPC. This is the highest reported CO2 uptake among the family of the activated porous carbonaceous materials. Thus, the porous carbon materials from asphalt have excellent properties for reversibly capturing CO2 at the well-head during the extraction of natural gas, a naturally occurring high pressure source of CO2. Through a pressure swing sorption process, when the asphalt-derived material is returned to 1 bar, the CO2 is released, thereby rendering a reversible capture medium that is highly efficient yet very inexpensive.

  14. [Study on the content and carbon isotopic composition of water dissolved inorganic carbon from rivers around Xi'an City].

    PubMed

    Guo, Wei; Li, Xiang-Zhong; Liu, Wei-Guo

    2013-04-01

    In this study, the content and isotopic compositions of water dissolved inorganic carbon (DIC) from four typical rivers (Chanhe, Bahe, Laohe and Heihe) around Xi'an City were studied to trace the possible sources of DIC. The results of this study showed that the content of DIC in the four rivers varied from 0.34 to 5.66 mmol x L(-1) with an average value of 1.23 mmol x L(-1). In general, the content of DIC increased from the headstream to the river mouth. The delta13C(DIC) of four rivers ranged from -13.3 per thousand to -7.2 per thousand, with an average value of -10.1 per thousand. The delta13C(DIC) values of river water were all negative (average value of -12.6 per thousand) at the headstream of four rivers, but the delta13C(DIC) values of downstream water were more positive (with an average value of -9.4 per thousand). In addition, delta13C(DIC) of river water showed relatively negative values (the average value of delta13C(DIC) was -10.5 per thousand) near the estuary of the rivers. The variation of the DIC content and its carbon isotope suggested that the DIC sources of the rivers varied from the headstream to the river mouth. The negative delta13C(DIC) value indicated that the DIC may originate from the soil CO2 at the headstream of the rivers. On the other hand, the delta13C(DIC) values of river water at the middle and lower reaches of rivers were more positive, and it showed that soil CO2 produced by respiration of the C4 plants (like corn) and soil carbonates with positive delta13C values may be imported into river water. Meanwhile, the input of pollutants with low delta13C(DIC) values may result in a decrease of delta13C(DIC) values in the rivers. The study indicated that the DIC content and carbon isotope may be used to trace the sources of DIC in rivers around Xi'an City. Our study may provide some basic information for tracing the sources of DIC of rivers in the small watershed area in the Loess Plateau of China.

  15. Rising atmospheric CO2 leads to large impact of biology on Southern Ocean CO2 uptake via changes of the Revelle factor

    PubMed Central

    Hauck, J; Völker, C

    2015-01-01

    The Southern Ocean is a key region for global carbon uptake and is characterized by a strong seasonality with the annual CO2 uptake being mediated by biological carbon drawdown in summer. Here we show that the contribution of biology to CO2 uptake will become even more important until 2100. This is the case even if biological production remains unaltered and can be explained by the decreasing buffer capacity of the ocean as its carbon content increases. The same amount of biological carbon drawdown leads to a more than twice as large reduction in CO2(aq) concentration and hence to a larger CO2 gradient between ocean and atmosphere that drives the gas exchange. While the winter uptake south of 44°S changes little, the summer uptake increases largely and is responsible for the annual mean response. The combination of decreasing buffer capacity and strong seasonality of biological carbon drawdown introduces a strong and increasing seasonality in the anthropogenic carbon uptake. Key Points Decrease of buffer capacity leads to stronger summer CO2 uptake in the future Biology will contribute more to future CO2 uptake in Southern Ocean Seasonality affects anthropogenic carbon uptake strongly PMID:26074650

  16. Inorganic carbon dynamics in the upwelling system off the Oregon coast and implications for commercial shellfish hatcheries

    NASA Astrophysics Data System (ADS)

    Vance, J. M.; Hales, B. R.

    2010-12-01

    The increasing absorption of anthropogenic CO2 by the global ocean and concomitant decrease in pH will alter seawater carbonate chemistry in ways that may negatively impact calcifying organisms. In particular, the change in saturation state (Ω) of calcium carbonate minerals calcite and aragonite may be energetically unfavorable for shell formation while favoring shell dissolution. Eastern boundary upwelling systems may provide insights into how ecosystems respond to future conditions of ocean acidification when deep water with high dissolved inorganic carbon (DIC), low pH and low Ω is forced toward the surface. Mortality in commercial seed stock and reduced wild set of the oyster Crassostrea gigas in the northeast Pacific during 2005-2009 reinforced the need for understanding biological responses to acidified ocean water. In response, a long-term strategy to understand local carbonate chemistry dynamics, seasonal perturbations and the effects on development of calcifying bivalves was developed. At present, a time-series of pCO2 measurements was implemented in April 2010 in Netarts Bay, Oregon at Whiskey Creek Shellfish Hatchery (WCH). The intake sits at a depth of 0.5-8ft and water is pumped in at 100gpm. A line taken off the intake is run continuously through a thermosalinograph at approximately 1.5gpm into a showerhead style equilibrator in which the headspace is recirculated by aerating the water for enhanced gas exchange. CO2 in equilibrated air is analyzed by NDIR. Additionally two discrete samples of intake seawater were taken across tidal cycles weekly and analyzed for total CO2 (TCO2) according to the methods of Hales et al. (2004) and pCO2 for quality control. The pCO2 in the bay exhibits a diurnal cycle representative of daytime photosynthesis and nighttime respiration. However, the phasing and profiles of these cycles are dominated by tidal mixing and are affected by the introduction of high pCO2 water during upwelling events. Diurnal pCO2 during

  17. Acidification at the Surface in the East Sea: A Coupled Climate-carbon Cycle Model Study

    NASA Astrophysics Data System (ADS)

    Park, Young-Gyu; Seol, Kyung-Hee; Boo, Kyung-On; Lee, Johan; Cho, Chunho; Byun, Young-Hwa; Seo, Seongbong

    2018-05-01

    This modeling study investigates the impacts of increasing atmospheric CO2 concentration on acidification in the East Sea. A historical simulation for the past three decades (1980 to 2010) was performed using the Hadley Centre Global Environmental Model (version 2), a coupled climate model with atmospheric, terrestrial and ocean cycles. As the atmospheric CO2 concentration increased, acidification progressed in the surface waters of the marginal sea. The acidification was similar in magnitude to observations and models of acidification in the global ocean. However, in the global ocean, the acidification appears to be due to increased in-situ oceanic CO2 uptake, whereas local processes had stronger effects in the East Sea. pH was lowered by surface warming and by the influx of water with higher dissolved inorganic carbon (DIC) from the northwestern Pacific. Due to the enhanced advection of DIC, the partial pressure of CO2 increased faster than in the overlying air; consequently, the in-situ oceanic uptake of CO2 decreased.

  18. Redox-responsive theranostic nanoplatforms based on inorganic nanomaterials.

    PubMed

    Han, Lu; Zhang, Xiao-Yong; Wang, Yu-Long; Li, Xi; Yang, Xiao-Hong; Huang, Min; Hu, Kun; Li, Lu-Hai; Wei, Yen

    2017-08-10

    Spurred on by advances in materials chemistry and nanotechnology, scientists have developed many novel nanopreparations for cancer diagnosis and therapy. To treat complex malignant tumors effectively, multifunctional nanomedicines with targeting ability, imaging properties and controlled drug release behavior should be designed and exploited. The therapeutic efficiency of loaded drugs can be dramatically improved using redox-responsive nanoplatforms which can sense the differences in the redox status of tumor tissues and healthy ones. Redox-sensitive nanocarriers can be constructed from both organic and inorganic nanomaterials; however, at present, drug delivery nanovectors progressively lean towards inorganic nanomaterials because of their facile synthesis/modification and their unique physicochemical properties. In this review, we focus specifically on the preparation and application of redox-sensitive nanosystems based on mesoporous silica nanoparticles (MSNs), carbon nanomaterials, magnetic nanoparticles, gold nanomaterials and other inorganic nanomaterials. We discuss relevant examples of redox-sensitive nanosystems in each category. Finally, we discuss current challenges and future strategies from the aspect of material design and practical application. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Inorganic Carbon and pH in the Gulf of Mexico: Understanding the Deepwater Horizon Region

    NASA Astrophysics Data System (ADS)

    Young, J.; Yvon-Lewis, S. A.; Bianchi, T. S.; Shields, M. R.; Du, M.

    2014-12-01

    The breakdown and respiration of oil compounds may contribute to the dissolved inorganic carbon (DIC) pool and thus ocean acidification. The Gulf of Mexico (GOM) has an abundance of natural seeps as well as numerous man-made structures that could provide a source of hydrocarbons to the water column. Samples of seawater were collected on the first GISR (Gulf Integrated Spill Research) cruise (G01) during the first week of July 2012. This cruise covered an area of ~1360 km2 roughly centered on the site of the Deepwater Horizon disaster. Alkalinity profiles for the southeastern most stations indicate lower (~100 μmol/kg) alkalinities at depth when compared to other stations sampled. This results in calculated pHs that are ~0.5 units lower at depth than they are at the other stations. Another group of stations show increased DIC concentrations on the order of 100-150 μmol/kg higher than average at depths at 800 m and 1200 m leading to calculated pHs about 0.2 to 0.4 below average for those depths in all of the stations sampled. These features may or may not be persistent in this region, and the elevated DIC concentrations may be related to organic matter (petroleum or other) oxidation. Samples were collected from this same region 2 years later (June 2014) and the persistence of these features will be discussed in the context of linkages with organic carbon respiration and low pHs.

  20. Ancient low–molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw

    USGS Publications Warehouse

    Drake, Travis W.; Wickland, Kimberly P.; Spencer, Robert G. M.; McKnight, Diane M.; Striegl, Robert G.

    2015-01-01

    Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high–temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low–molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thaw and the outgassing of CO2 to the atmosphere by soils and nearby inland waters.

  1. Ancient low-molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw.

    PubMed

    Drake, Travis W; Wickland, Kimberly P; Spencer, Robert G M; McKnight, Diane M; Striegl, Robert G

    2015-11-10

    Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high-temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low-molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thaw and the outgassing of CO2 to the atmosphere by soils and nearby inland waters.

  2. Ancient low–molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw

    PubMed Central

    Drake, Travis W.; Wickland, Kimberly P.; Spencer, Robert G. M.; McKnight, Diane M.; Striegl, Robert G.

    2015-01-01

    Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high–temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low–molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thaw and the outgassing of CO2 to the atmosphere by soils and nearby inland waters. PMID:26504243

  3. Hydrologic Transport of Dissolved Inorganic Carbon and Its Control on Chemical Weathering

    NASA Astrophysics Data System (ADS)

    Calabrese, Salvatore; Parolari, Anthony J.; Porporato, Amilcare

    2017-10-01

    Chemical weathering is one of the major processes interacting with climate and tectonics to form clays, supply nutrients to soil microorganisms and plants, and sequester atmospheric CO2. Hydrology and dissolution kinetics have been emphasized as factors controlling chemical weathering rates. However, the interaction between hydrology and transport of dissolved inorganic carbon (DIC) in controlling weathering has received less attention. In this paper, we present an analytical model that couples subsurface water and chemical molar balance equations to analyze the roles of hydrology and DIC transport on chemical weathering. The balance equations form a dynamical system that fully determines the dynamics of the weathering zone chemistry as forced by the transport of DIC. The model is formulated specifically for the silicate mineral albite, but it can be extended to other minerals, and is studied as a function of percolation rate and water transit time. Three weathering regimes are elucidated. For very small or large values of transit time, the weathering is limited by reaction kinetics or transport, respectively. For intermediate values, the system is transport controlled and is sensitive to transit time. We apply the model to a series of watersheds for which we estimate transit times and identify the type of weathering regime. The results suggest that hydrologic transport of DIC may be as important as reaction kinetics and dilution in determining chemical weathering rates.

  4. [Effects of combined application of biochar and inorganic fertilizers on the available phosphorus content of upland red soil].

    PubMed

    Jing, Yan; Chen, Xiao-min; Liu, Zu-xiang; Huang, Qian-ru; LiI, Qiu-xia; Chen, Chen; Lu, Shao-shan

    2013-04-01

    Aiming at the low content of available phosphorus in upland red soil of Southern China, this paper studied the effects of combined application of biochar and inorganic fertilizers on the available phosphorus and organic carbon contents and the pH of this soil. With the combined application of biochar and inorganic fertilizers, the soil physical and chemical properties improved to different degrees. As compared with the control, the soil pH and the soil organic carbon and available phosphorus contents at different growth stages of oil rape after the combined application of biochar and inorganic fertilizers all had an improvement, with the increments at bolting stage, flowering stage, and ripening stage being 16%, 24% and 26%, 23%, 34% and 38%, and 100%, 191% and 317% , respectively. The soil pH and the soil organic carbon and available phosphorus contents were increased with the increasing amount of applied biochar. Under-the application of biochar, the soil available phosphorus had a significant correlation with the soil pH and soil organic carbon content. This study could provide scientific basis to improve the phosphorus deficiency and the physical and chemical properties of upland red soil.

  5. The elemental stoichiometry (C, Si, N, P) of the Hebrides Shelf and its role in carbon export

    NASA Astrophysics Data System (ADS)

    Painter, Stuart C.; Hartman, Susan E.; Kivimäe, Caroline; Salt, Lesley A.; Clargo, Nicola M.; Daniels, Chris J.; Bozec, Yann; Daniels, Lucie; Allen, Stephanie; Hemsley, Victoria S.; Moschonas, Grigorios; Davidson, Keith

    2017-12-01

    A detailed analysis of the internal stoichiometry of a temperate latitude shelf sea system is presented which reveals strong vertical and horizontal gradients in dissolved nutrient and particulate concentrations and in the elemental stoichiometry of those pools. Such gradients have implications for carbon and nutrient export from coastal waters to the open ocean. The mixed layer inorganic nutrient stoichiometry shifted from balanced N:P in winter, to elevated N:P in spring and to depleted N:P in summer, relative to the Redfield ratio. This pattern suggests increased likelihood of P limitation of fast growing phytoplankton species in spring and of N limitation of slower growing species in summer. However, as only silicate concentrations were below potentially limiting concentrations during summer and autumn the stoichiometric shifts in inorganic nutrient N:P are considered due to phytoplankton nutrient preference patterns rather than nutrient exhaustion. Elevated particulate stoichiometries corroborate non-Redfield optima underlying organic matter synthesis and nutrient uptake. Seasonal variation in the stoichiometry of the inorganic and organic nutrient pools has the potential to influence the efficiency of nutrient export. In summer, when organic nutrient concentrations were at their highest and inorganic nutrient concentrations were at their lowest, the organic nutrient pool was comparatively C poor whilst the inorganic nutrient pool was comparatively C rich. The cross-shelf export of these pools at this time would be associated with different efficiencies regardless of the total magnitude of exchange. In autumn the elemental stoichiometries increased with depth in all pools revealing widespread carbon enrichment of shelf bottom waters with P more intensely recycled than N, N more intensely recycled than C, and Si weakly remineralized relative to C. Offshelf carbon fluxes were most efficient via the inorganic nutrient pool, intermediate for the organic nutrient

  6. Agricultural Liming, Irrigation, and Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    McGill, B. M.; Hamilton, S. K.

    2015-12-01

    Row crop farmers routinely add inorganic carbon to soils in the form of crushed lime (e.g., calcite or dolomite minerals) and/or inadvertently as bicarbonate alkalinity naturally dissolved in groundwater used for irrigation. In the soil these carbonates can act as either a source or sink of carbon dioxide, depending in large part on nitrogen fertilization and nitrification. The potentially variable fate of lime carbon is not accounted for in the IPCC greenhouse gas inventory model for lime emissions, which assumes that all lime carbon becomes carbon dioxide (irrigation additions are not accounted for). In a corn-soybean-wheat crop rotation at the Kellogg Biological Station Long Term Ecological Research site in southwest Michigan, we are collecting soil porewater from several depths in the vadose zone across a nitrogen fertilizer gradient with and without groundwater irrigation. The soil profile in this region is dominated by carbonate rich glacial outwash that lies 1.5 m below a carbonate-leached zone. We analyze the porewater stoichiometry of calcium, magnesium, and carbonate alkalinity in a conceptual model to reveal the source/sink fate of inorganic carbon. High nitrate porewater concentrations are associated with net carbon dioxide production in the carbonate-leached zone, according to our model. This suggests that the acidity associated with nitrification of the nitrogen fertilizer, which is evident from soil pH measurements, is driving the ultimate fate of lime carbon in the vadose zone. Irrigation is a significant source of both alkalinity and nitrate in drier years, compared to normal rates of liming and fertilization. We will also explore the observed dramatic changes in porewater chemistry and the relationship between irrigation and inorganic carbon fate above and within the native carbonate layer.

  7. Water column profiles of particulate inorganic carbon in the northeast subarctic Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Sutton, J. N.; Bishop, J. K.; Martinez, E. J.; Weiss, G. A.; Weiss, A.; Derr, A.; Strubhar, W.; Robert, M.; Wood, T.

    2013-12-01

    High resolution and real-time measurement of particulate inorganic carbon (PIC) content in seawater is necessary to improve our spatial and temporal understanding of marine carbon flux and the possible effects of ocean acidification on the biological pump. On four occasions since August 2012, we have mapped PIC distribution from surface to bottom at 26 stations along the IOS-Canada Line P transect from western Vancouver Island, BC, Canada to Ocean Station PAPA, 50N 145W using a prototype (PIC001) and a near-commercial quality (PIC008) optical birefringence sensor. The sensors are highly modified 6000m-rated WETLabs C-star transmissometers, which use a polarized laser beam and a cross-polarized receiver to measure photons emitted after passing through birefringent solids. At major stations along Line P (P2, P4, P8, P12, P16, P20, P26), one-liter rosette-collected calibration water samples were filtered through 0.45 μm Supor filters using a small-volume direct filtration system. These samples were analysed for acid-leachable particulate elements (with emphasis on Ca, Na, and Mg) by inductively coupled plasma mass spectrometry (ICPMS). ICPMS PIC was calculated as residual Ca after correction for seawater Ca using Na data. Here we report results for late summer (Aug. 2012) and winter (Feb. 2013). As expected, high levels of PIC (> 100 nmol L-1 to > 2000 nmol L-1) were found in surface waters but rapidly declined at depths greater than 200m and increased again in the nepheloid layer (>50 nmol L-1). Striking seasonal differences in PIC content and PIC profile shape were observed particularly at near shore stations P2, P4, P8 and P12. The results from this research, including sensor evolution and calibration performance, will be presented.

  8. Mycorrhizal mediated feedbacks influence net carbon gain and nutrient uptake in Andropogon gerardii.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Miller, R. M.; Miller, S. P.; Jastrow, J. D.

    The carbon sink strength of arbuscular mycorrhizal fungi (AMF) was investigated by comparing the growth dynamics of mycorrhizal and nonmycorrhizal Andropogon gerardii plants over a wide range of equivalent tissue phosphorus : nitrogen (P : N) ratios. Host growth, apparent photosynthesis (A{sub net}), net C gain (C{sub n}) and P and N uptake were evaluated in sequential harvests of mycorrhizal and nonmycorrhizal A. gerardii plants. Response curves were used to assess the effect of assimilate supply on the mycorrhizal symbiosis in relation to the association of C with N and P. Mycorrhizal plants had higher C{sub n} than nonmycorrhizal plantsmore » at equivalent shoot P : N ratios even though colonization did not affect plant dry mass. The higher C{sub n} in mycorrhizal plants was related to both an increase in specific leaf area and enhanced photosynthesis. The additional carbon gain associated with the mycorrhizal condition was not allocated to root biomass. The C{sub n} in the mycorrhizal plants was positively related to the proportion of active colonization in the roots. The calculated difference between C{sub n} values in mycorrhizal and nonmycorrhizal plants, C{sub diff}, appeared to correspond to the sink strength of the AMF and was not an indirect result of enhanced nutrition in mycorrhizal plants.« less

  9. Inorganic Polymer Matrix Composite Strength Related to Interface Condition

    PubMed Central

    Radford, Donald W.; Grabher, Andrew; Bridge, John

    2009-01-01

    Resin transfer molding of an inorganic polymer binder was successfully demonstrated in the preparation of ceramic fiber reinforced engine exhaust valves. Unfortunately, in the preliminary processing trials, the resulting composite valves were too brittle for in-engine evaluation. To address this limited toughness, the effectiveness of a modified fiber-matrix interface is investigated through the use of carbon as a model material fiber coating. After sequential heat treatments composites molded from uncoated and carbon-coated fibers are compared using room temperature 3-point bend testing. Carbon-coated Nextel fiber reinforced geopolymer composites demonstrated a 50% improvement in strength, versus that of the uncoated fiber reinforced composites, after the 250 °C postcure.

  10. [Impact of Rocky Desertification Treatment on Underground Water Chemistry and Dissolved Inorganic Carbon Isotope in Karst Areas].

    PubMed

    Xiao, Shi-zhen; Xiong, Kang-ning; Lan, Jia-cheng; Zhang, Hui; Yang, Long

    2015-05-01

    Five springs representing different land-use types and different karst rocky desertification treatment models were chosen at the Huajiang Karst Rocky Desertification Treatment Demonstration Site in Guanling-Zhenfeng Counties in Guizhou, to analyze the features of underground water chemistry and dissolved inorganic carbon isotopes (δ13C(DIC)) and reveal the effect of rocky desertification treatment on karstification and water quality. It was found that, the underground water type of the research area was HCO3-Ca; the water quality of the springs which were relatively less affected by human activities including Shuijingwan Spring (SJW) , Gebei Spring (GB), and Maojiawan Spring (MJW) was better than those relatively more affected by human activities including Diaojing Spring (DJ) and Tanjiazhai Spring (TJZ) , the main ion concentrations and electrical conductivity of which were higher; pH, SIc and pCO2 were sensitive to land-use types and rocky desertification treatment, which could be shown by the higher pH and SIc and lower pCO2 in MJW than those in the other four springs; (Ca(2+) + Mg2+)/HCO(3-) of SJW, MJW and GB were nearly 1:1, dominated by carbonate rock weathering by carbon acid, while the (Ca(2+) + Mg2+) of DJ and TJZ was much higher than HCO3-, suggesting that sulfate and nitrate might also dissolve carbonate rock because of the agricultural activities; δ13C(DIC) was lighter in wet season because of the higher biological activities; the average δ13C(DIC) was in the order of DJ (-12.79 per thousand) < SJW (-12.48 per thousand) < GB (-10.76 per thousand)) < MJW (-10.30 per thousand) < TJZ (-6.70 per thousand), which demonstrated that δ13C(DIC) would be heavier after rocky desertification and lighter after the rocky desertification are treated and controlled.

  11. Inside out: efflux of carbon dioxide from leaves represents more than leaf metabolism.

    PubMed

    Stutz, Samantha S; Anderson, Jeremiah; Zulick, Rachael; Hanson, David T

    2017-05-17

    High concentrations of inorganic carbon in the xylem, produced from root, stem, and branch respiration, travel via the transpiration stream and eventually exit the plant through distant tissues as CO2. Unlike previous studies that focused on the efflux of CO2 from roots and woody tissues, we focus on efflux from leaves and the potential effect on leaf respiration measurements. We labeled transported inorganic carbon, spanning reported xylem concentrations, with 13C and then manipulated transpiration rates in the dark in order to vary the rates of inorganic carbon supply to cut leaves from Brassica napus and Populus deltoides. We used tunable diode laser absorbance spectroscopy to directly measure the rate of gross 13CO2 efflux, derived from inorganic carbon supplied from outside of the leaf, relative to gross 12CO2 efflux generated from leaf cells. These experiemnts showed that 13CO2 efflux was dependent upon the rate of inorganic carbon supply to the leaf and the rate of transpiration. Our data show that the gross leaf efflux of xylem-transported CO2 is likely small in the dark when rates of transpiration are low. However, gross leaf efflux of xylem-transported CO2 could approach half the rate of leaf respiration in the light when transpiration rates and branch inorganic carbon concentrations are high, irrespective of the grossly different petiole morphologies in our experiment. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  12. Lack of Plasma Protein Hemopexin Results in Increased Duodenal Iron Uptake.

    PubMed

    Fiorito, Veronica; Geninatti Crich, Simonetta; Silengo, Lorenzo; Aime, Silvio; Altruda, Fiorella; Tolosano, Emanuela

    2013-01-01

    The body concentration of iron is regulated by a fine equilibrium between absorption and losses of iron. Iron can be absorbed from diet as inorganic iron or as heme. Hemopexin is an acute phase protein that limits iron access to microorganisms. Moreover, it is the plasma protein with the highest binding affinity for heme and thus it mediates heme-iron recycling. Considering its involvement in iron homeostasis, it was postulated that hemopexin may play a role in the physiological absorption of inorganic iron. Hemopexin-null mice showed elevated iron deposits in enterocytes, associated with higher duodenal H-Ferritin levels and a significant increase in duodenal expression and activity of heme oxygenase. The expression of heme-iron and inorganic iron transporters was normal. The rate of iron absorption was assessed by measuring the amount of (57)Fe retained in tissues from hemopexin-null and wild-type animals after administration of an oral dose of (57)FeSO4 or of (57)Fe-labelled heme. Higher iron retention in the duodenum of hemopexin-null mice was observed as compared with normal mice. Conversely, iron transfer from enterocytes to liver and bone marrow was unaffected in hemopexin-null mice. The increased iron level in hemopexin-null duodenum can be accounted for by an increased iron uptake by enterocytes and storage in ferritins. These data indicate that the lack of hemopexin under physiological conditions leads to an enhanced duodenal iron uptake thus providing new insights to our understanding of body iron homeostasis.

  13. Relevance of octanol-water distribution measurements to the potential ecological uptake of multi-walled carbon nanotubes.

    PubMed

    Petersen, Elijah J; Huang, Qingguo; Weber, Walter J

    2010-05-01

    Many potential applications of carbon nanotubes (CNTs) require various physicochemical modifications prior to use, suggesting that nanotubes having varied properties may pose risks in ecosystems. A means for estimating bioaccumulation potentials of variously modified CNTs for incorporation in predictive fate models would be highly valuable. An approach commonly used for sparingly soluble organic contaminants, and previously suggested for use as well with carbonaceous nanomaterials, involves measurement of their octanol-water partitioning coefficient (KOW) values. To test the applicability of this approach, a methodology was developed to measure apparent octanol-water distribution behaviors for purified multi-walled carbon nanotubes and those acid treated. Substantial differences in apparent distribution coefficients between the two types of CNTs were observed, but these differences did not influence accumulation by either earthworms (Eisenia foetida) or oligochaetes (Lumbriculus variegatus), both of which showed minimal nanotube uptake for both types of nanotubes. The results suggest that traditional distribution behavior-based KOW approaches are likely not appropriate for predicting CNT bioaccumulation. Copyright (c) 2010 SETAC.

  14. Impacts of drought on regional carbon uptake dynamics in the Southwestern US, using the New Mexico Elevation Gradient of flux towers and the Temperature-Greenness model.

    NASA Astrophysics Data System (ADS)

    Krofcheck, D. J.; Lippitt, C.; Litvak, M. E.

    2014-12-01

    Semi-arid regions store approximately 568 Gt of carbon, roughly 18% of the global carbon reserves. Drought remains one of the largest sources of climatic stress in semi-arid regions globally. The impacts of these expansive, severe droughts on terrestrial productivity can be substantial and difficult to quantify spatially. The semi-arid Southwestern US suffered an expansive drought in 2011 which precipitated significant decline in ecosystem function and woody mortality across the region. We used the New Mexico Elevation Gradient (NMEG) cluster of flux towers, which provided in-situ measures of carbon flux via eddy-covariance to estimate the decreases in gross primary production across six dominant vegetation types in the region. Relative to a wet year, the largest decrease in cumulative carbon uptake we measured was 60% (a reduction of 200 g C /m2 annually) at the ponderosa pine site. The pattern of decreased carbon sequestration was consistent across the gradient, with the C4 grasslands shifting from carbon neutral to a source of 50 g C / m2 in response to the drought and desert shrublands sink strength reduced by 100%, (~50 g C /m2 annually). Juniper savannas, PJ woodlands, and mixed conifer subalpine woodlands all showed a decrease in carbon sequestration of roughly 100 g C /m2 annually. Rough scaling of these results suggest this drought could have resulted in a reduction of carbon uptake of 20 Tg C in NM alone. To more realistically estimate the decrease in carbon sequestration due to drought, we used results from the NMEG to parameterize the Temperature-Greenness model, a remote sensing based approach to scale these estimates to the region, focusing on the six dominant vegetation types represented by the NMEG (accounts for 60% of total land area in NM). This model is driven by 16-day averages of MODIS land surface temperature and the enhanced vegetation index. We used the Southwest Regional GAP analysis classification data to bin NM landcover into

  15. Carbon: Nitrogen Interaction Regulates Expression of Genes Involved in N-Uptake and Assimilation in Brassica juncea L.

    PubMed Central

    Goel, Parul; Bhuria, Monika; Kaushal, Mamta

    2016-01-01

    In plants, several cellular and metabolic pathways interact with each other to regulate processes that are vital for their growth and development. Carbon (C) and Nitrogen (N) are two main nutrients for plants and coordination of C and N pathways is an important factor for maintaining plant growth and development. In the present work, influence of nitrogen and sucrose (C source) on growth parameters and expression of genes involved in nitrogen transport and assimilatory pathways was studied in B. juncea seedlings. For this, B. juncea seedlings were treated with four combinations of C and N source viz., N source alone (-Suc+N), C source alone (+Suc-N), with N and C source (+Suc+N) or without N and C source (-Suc-N). Cotyledon size and shoot length were found to be increased in seedlings, when nitrogen alone was present in the medium. Distinct expression pattern of genes in both, root and shoot tissues was observed in response to exogenously supplied N and C. The presence or depletion of nitrogen alone in the medium leads to severe up- or down-regulation of key genes involved in N-uptake and transport (BjNRT1.1, BjNRT1.8) in root tissue and genes involved in nitrate reduction (BjNR1 and BjNR2) in shoot tissue. Moreover, expression of several genes, like BjAMT1.2, BjAMT2 and BjPK in root and two genes BjAMT2 and BjGS1.1 in shoot were found to be regulated only when C source was present in the medium. Majority of genes were found to respond in root and shoot tissues, when both C and N source were present in the medium, thus reflecting their importance as a signal in regulating expression of genes involved in N-uptake and assimilation. The present work provides insight into the regulation of genes of N-uptake and assimilatory pathway in B. juncea by interaction of both carbon and nitrogen. PMID:27637072

  16. Ionising radiation effect on the luminescence emission of inorganic and biogenic calcium carbonates

    NASA Astrophysics Data System (ADS)

    Boronat, C.; Correcher, V.; Virgos, M. D.; Garcia-Guinea, J.

    2017-06-01

    As known, the luminescence emission of mineral phases could be potentially employed for dosimetric purposes in the case of radiological terrorism or radiation accident where conventional monitoring is not available. In this sense, this paper reports on the thermo- (TL) and cathodoluminescence (CL) emission of both biogenic (common periwinkle - littorina littorera - shell made of calcite 90% and aragonite 10%) and inorganic (aragonite 100%) Ca-rich carbonates previously characterized by X-ray diffraction and Raman spectroscopy. Whereas the aragonite sample displays the main CL waveband peaked in the red region (linked to point defects), the more intense emission obtained from the common periwinkle shell appears at higher energies (mainly associated with structural defects). The UV-blue TL emission of the samples, regardless of the origin, displays (i) an acceptable ionizing radiation sensitivity, (ii) linear dose response in the range of interest (up to 8 Gy), (iii) reasonable stability of the TL signal after 700 h of storage with an initial decay of ca. 88% for the mineral sample and 60% for the biogenic sample and maintaining the stability from 150 h onwards. (iv) The tests of thermal stability of the TL emission performed in the range of 180-320 °C confirm a continuum in the trap system.

  17. The contribution of human activities to dissolved inorganic carbon fluxes in a karst underground river system: evidence from major elements and δ¹³C(DIC) in Nandong, Southwest China.

    PubMed

    Jiang, Yongjun

    2013-09-01

    Generally, the DIC in karst groundwater is dominantly derived from carbonate dissolution by carbonic acid. However, recently increases in the inorganic carbon flux have been linked to human activities, which nitric and sulfuric acids may contribute to carbonate dissolution. In order to quantify the sources and fluxes of DIC, and evaluate the carbon isotopic evolution of groundwater in Southwest China, the carbonate dissolution by carbonic, sulfuric and nitric acids was evaluated by hydrochemistry and δ¹³C(DIC)of groundwater. The results show that: (1) groundwater collected from residential and agricultural areas, showed higher DIC concentrations and δ¹³C(DIC) than those in groundwater collected from forested and grass land areas; (2) the contributions of carbonate dissolution by carbonic acid to total DIC concentrations in groundwater collected from forested and grass land areas averaged 99%; (3) the contributions of carbonate dissolution by carbonic acid to total DIC concentrations in groundwater, collected from residential and agricultural areas, varied from 40% to 77% with a mean percentage of 62%; (4) while the contributions of carbonate dissolution by sulfuric and nitric acids to total DIC concentrations in groundwater, collected from residential and agricultural areas, varied from 23% to 60% with a mean percentage of 38%; and (5) the δ¹³C(DIC) approaching a value of around -14‰, with a molar ratio between (Ca²⁺+Mg²⁺) and HCO₃⁻ of around 0.5 in groundwater, indicated that the carbonate was dissolved by soil CO₂ from C₃ vegetation under open system conditions. While the δ¹³C(DIC) varying from -5‰ to -11‰, with a variational molar ratio between (Ca²⁺+Mg²⁺) and HCO₃⁻ of 0.5 to 0.8 in groundwater, indicated that carbonate dissolution was controlled by soil CO₂ (from C₃ vegetation), HNO₃ and H₂SO₄. Also, this study indicated that the amount of soil or atmospheric CO₂ consumed during carbonate weathering should

  18. Investigations of inorganic and hybrid inorganic-organic nanostructures

    NASA Astrophysics Data System (ADS)

    Kam, Kinson Chihang

    This thesis focuses on the exploratory synthesis and characterization of inorganic and hybrid inorganic-organic nanomaterials. In particular, nanostructures of semiconducting nitrides and oxides, and hybrid systems of nanowire-polymer composites and framework materials, are investigated. These materials are characterized by a variety of techniques for structure, composition, morphology, surface area, optical properties, and electrical properties. In the study of inorganic nanomaterials, gallium nitride (GaN), indium oxide (In2O3), and vanadium dioxide (VO2) nanostructures were synthesized using different strategies and their physical properties were examined. GaN nanostructures were obtained from various synthetic routes. Solid-state ammonolysis of metastable gamma-Ga2O 3 nanoparticles was found to be particularly successful; they achieved high surface areas and photoluminescent study showed a blue shift in emission as a result of surface and size defects. Similarly, In2O3 nanostructures were obtained by carbon-assisted solid-state syntheses. The sub-oxidic species, which are generated via a self-catalyzed vapor-liquid-solid mechanism, resulted in 1D nanostructures including nanowires, nanotrees, and nanobouquets upon oxidation. On the other hand, hydrothermal methods were used to obtain VO2 nanorods. After post-thermal treatment, infrared spectroscopy demonstrated that these nanorods exhibit a thermochromic transition with temperature that is higher by ˜10°C compared to the parent material. The thermochromic behavior indicated a semiconductor-to-metal transition associated with a structural transformation from monoclinic to rutile. The hybrid systems, on the other hand, enabled their properties to be tunable. In nanowire-polymer composites, zinc oxide (ZnO) and silver (Ag) nanowires were synthesized and incorporated into polyaniline (PANI) and polypyrrole (PPy) via in-situ and ex-situ polymerization method. The electrical properties of these composites are

  19. A lake classification concept for a more accurate global estimate of the dissolved inorganic carbon export from terrestrial ecosystems to inland waters.

    PubMed

    Engel, Fabian; Farrell, Kaitlin J; McCullough, Ian M; Scordo, Facundo; Denfeld, Blaize A; Dugan, Hilary A; de Eyto, Elvira; Hanson, Paul C; McClure, Ryan P; Nõges, Peeter; Nõges, Tiina; Ryder, Elizabeth; Weathers, Kathleen C; Weyhenmeyer, Gesa A

    2018-03-26

    The magnitude of lateral dissolved inorganic carbon (DIC) export from terrestrial ecosystems to inland waters strongly influences the estimate of the global terrestrial carbon dioxide (CO 2 ) sink. At present, no reliable number of this export is available, and the few studies estimating the lateral DIC export assume that all lakes on Earth function similarly. However, lakes can function along a continuum from passive carbon transporters (passive open channels) to highly active carbon transformers with efficient in-lake CO 2 production and loss. We developed and applied a conceptual model to demonstrate how the assumed function of lakes in carbon cycling can affect calculations of the global lateral DIC export from terrestrial ecosystems to inland waters. Using global data on in-lake CO 2 production by mineralization as well as CO 2 loss by emission, primary production, and carbonate precipitation in lakes, we estimated that the global lateral DIC export can lie within the range of [Formula: see text] to [Formula: see text] Pg C yr -1 depending on the assumed function of lakes. Thus, the considered lake function has a large effect on the calculated lateral DIC export from terrestrial ecosystems to inland waters. We conclude that more robust estimates of CO 2 sinks and sources will require the classification of lakes into their predominant function. This functional lake classification concept becomes particularly important for the estimation of future CO 2 sinks and sources, since in-lake carbon transformation is predicted to be altered with climate change.

  20. A lake classification concept for a more accurate global estimate of the dissolved inorganic carbon export from terrestrial ecosystems to inland waters

    NASA Astrophysics Data System (ADS)

    Engel, Fabian; Farrell, Kaitlin J.; McCullough, Ian M.; Scordo, Facundo; Denfeld, Blaize A.; Dugan, Hilary A.; de Eyto, Elvira; Hanson, Paul C.; McClure, Ryan P.; Nõges, Peeter; Nõges, Tiina; Ryder, Elizabeth; Weathers, Kathleen C.; Weyhenmeyer, Gesa A.

    2018-04-01

    The magnitude of lateral dissolved inorganic carbon (DIC) export from terrestrial ecosystems to inland waters strongly influences the estimate of the global terrestrial carbon dioxide (CO2) sink. At present, no reliable number of this export is available, and the few studies estimating the lateral DIC export assume that all lakes on Earth function similarly. However, lakes can function along a continuum from passive carbon transporters (passive open channels) to highly active carbon transformers with efficient in-lake CO2 production and loss. We developed and applied a conceptual model to demonstrate how the assumed function of lakes in carbon cycling can affect calculations of the global lateral DIC export from terrestrial ecosystems to inland waters. Using global data on in-lake CO2 production by mineralization as well as CO2 loss by emission, primary production, and carbonate precipitation in lakes, we estimated that the global lateral DIC export can lie within the range of {0.70}_{-0.31}^{+0.27} to {1.52}_{-0.90}^{+1.09} Pg C yr-1 depending on the assumed function of lakes. Thus, the considered lake function has a large effect on the calculated lateral DIC export from terrestrial ecosystems to inland waters. We conclude that more robust estimates of CO2 sinks and sources will require the classification of lakes into their predominant function. This functional lake classification concept becomes particularly important for the estimation of future CO2 sinks and sources, since in-lake carbon transformation is predicted to be altered with climate change.

  1. Influence of surface chemistry of carbon materials on their interactions with inorganic nitrogen contaminants in soil and water.

    PubMed

    Sumaraj; Padhye, Lokesh P

    2017-10-01

    Inorganic nitrogen contaminants (INC) (NH 4 + , NO 3 - , NO 2 - , NH 3 , NO, NO 2 , and N 2 O) pose a growing risk to the environment, and their remediation methods are highly sought after. Application of carbon materials (CM), such as biochar and activated carbon, to remediate INC from agricultural fields and wastewater treatment plants has gained a significant interest since past few years. Understanding the role of surface chemistry of CM in adsorption of various INC is highly critical to increase adsorption efficiency as well as to assess the long term impact of using these highly recalcitrant CM for remediation of INC. Critical reviews of adsorption studies related to INC have revealed that carbon surface chemistry (surface functional groups, pH, Eh, elemental composition, and mineral content) has significant influence on adsorption of INC. Compared to basic functional groups, oxygen containing surface functional groups have been found to be more influential for adsorption of INC. However, basic sites on carbon materials still play an important role in chemisorption of anionic INC. Apart from surface functional groups, pH, Eh and pH zpc of CM and elemental and mineral composition of its surface are important properties capable of altering INC interactions with CM. This review summarizes our current understanding of INC interactions with CM's surface through the known chemisorption mechanisms: electrostatic interaction, hydrogen bonding, electron donor-acceptor mechanism, hydrophobic and hydrophilic interaction, chemisorption aided by minerals, and interactions influenced by pH and elemental composition. Change in surface chemistry of CM in soil during aging is also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Correlating single-molecule and ensemble-average measurements of peptide adsorption onto different inorganic materials.

    PubMed

    Kim, Seong-Oh; Jackman, Joshua A; Mochizuki, Masahito; Yoon, Bo Kyeong; Hayashi, Tomohiro; Cho, Nam-Joon

    2016-06-07

    The coating of solid-binding peptides (SBPs) on inorganic material surfaces holds significant potential for improved surface functionalization at nano-bio interfaces. In most related studies, the goal has been to engineer peptides with selective and high binding affinity for a target material. The role of the material substrate itself in modulating the adsorption behavior of a peptide molecule remains less explored and there are few studies that compare the interaction of one peptide with different inorganic substrates. Herein, using a combination of two experimental techniques, we investigated the adsorption of a 16 amino acid-long random coil peptide to various inorganic substrates - gold, silicon oxide, titanium oxide and aluminum oxide. Quartz crystal microbalance-dissipation (QCM-D) experiments were performed in order to measure the peptide binding affinity for inorganic solid supports at the ensemble average level, and atomic force microscopy (AFM) experiments were conducted in order to determine the adhesion force of a single peptide molecule. A positive trend was observed between the total mass uptake of attached peptide and the single-molecule adhesion force on each substrate. Peptide affinity for gold was appreciably greater than for the oxide substrates. Collectively, the results obtained in this study offer insight into the ways in which inorganic materials can differentially influence and modulate the adhesion of SBPs.

  3. Graded porous inorganic materials derived from self-assembled block copolymer templates.

    PubMed

    Gu, Yibei; Werner, Jörg G; Dorin, Rachel M; Robbins, Spencer W; Wiesner, Ulrich

    2015-03-19

    Graded porous inorganic materials directed by macromolecular self-assembly are expected to offer unique structural platforms relative to conventional porous inorganic materials. Their preparation to date remains a challenge, however, based on the sparsity of viable synthetic self-assembly pathways to control structural asymmetry. Here we demonstrate the fabrication of graded porous carbon, metal, and metal oxide film structures from self-assembled block copolymer templates by using various backfilling techniques in combination with thermal treatments for template removal and chemical transformations. The asymmetric inorganic structures display mesopores in the film top layers and a gradual pore size increase along the film normal in the macroporous sponge-like support structure. Substructure walls between macropores are themselves mesoporous, constituting a structural hierarchy in addition to the pore gradation. Final graded structures can be tailored by tuning casting conditions of self-assembled templates as well as the backfilling processes. We expect that these graded porous inorganic materials may find use in applications including separation, catalysis, biomedical implants, and energy conversion and storage.

  4. Influence of inoculum type, inorganic salt and nitrogen to carbon ratio on sclerotium formation and carotenoid production in surface culture of Penicillium sp. PT95.

    PubMed

    Han, Jian-Rong; Xu, Jun; Zhou, Xiao-Mei

    2002-01-01

    This study examined the respective effect of inoculum type, inorganic salt and nitrogen to carbon ratio on sclerotium formation and carotenoid production in surface culture of Penicillium sp. PT95. Neither the spore inoculum nor the mycelial pellet inoculum could result in the formation of sclerotium on a modified Czapek agar medium after incubation of 28 days, whereas the inoculum in the form of sclerotium caused the formation of numerous orange, sand-shaped sclerotia after incubation of 14 days. Among four inorganic salts tested, K(2)HPO(4) was more essential to the sclerotium formation and carotenoid production of strain PT95 as compared to KCl, MgSO(4) or FeSO(4). It was also shown that the combination of K(2)HPO(4), KCl and MgSO(4) could produce the best positive cooperation and give the highest sclerotia biomass (782 mg/plate) and carotenoid content in sclerotium (420 microg/g of dry sclerotia) as well as pigment yield (328 microg/plate). The medium containing 0.24 approximately 0.48 g/l sodium nitrate-nitrogen was effective to both the sclerotium formation and carotenoid production of strain PT95 when available maltose-carbon concentrations were at 5.26 approximately 21.05 g/l. The optimal N:C ratio was found to be 1:25.

  5. Biogeochemistry of carbonates: recorders of past oceans and climate.

    PubMed

    Rickaby, Rosalind E M; Schrag, Daniel P

    2005-01-01

    Trace metal proxies bound within the calcium carbonate tests of oceanic organisms provide a unique insight into how the climate system works on timescales which span eight orders of magnitude, from annual to hundreds of millions of years. Whilst the motivation for developing these proxies was the idea that thermodynamic equilibria control the chemistry during precipitation, in reality the application of trace metal proxies relies upon empirical calibration. Such calibration can be applied to a wide range of environmental reconstructions, but more accurate application of proxies requires a mechanistic understanding of the biomineralization process. The partitioning of trace metals into biogenic carbonates reflects to some extent the same pattern as an inorganic crystal, but there is an additional selectivity and differing environmental sensitivity to, e.g., temperature, which confirms that biochemical processes also play a role in the uptake and assembly of ions into a crystal. Different organisms display differing degrees of biological control on their carbonate chemistry. Aragonitic coral chemistry is most similar to inorganic precipitation from seawater whilst coccolithophores are most different, and these contrasts correlate with the degree of control of the organism over its biomineralization. Selectivity between Ca and trace metals during biomineralization arises during transport by pumps, channels, or nucleation upon an organic matrix. The biological selectivity of the transporters and matrix is strikingly similar in its base chemistry to the selective assembly of ions into a crystal. In each case, the selectivity between Ca2+ and trace metals derives from the balance between the energy required for dehydration of the hexaaqua complex of the cation, and the energy released from the new coordination geometry of binding with either carbonyl oxygen from polysaccharides or amino acids, or carbonate oxygen in the crystal. This is a speculative idea, but with some

  6. A mechanistic, globally-applicable model of plant nitrogen uptake, retranslocation and fixation

    NASA Astrophysics Data System (ADS)

    Fisher, J. B.; Tan, S.; Malhi, Y.; Fisher, R. A.; Sitch, S.; Huntingford, C.

    2008-12-01

    Nitrogen is one of the nutrients that can most limit plant growth, and nitrogen availability may be a controlling factor on biosphere responses to climate change. We developed a plant nitrogen assimilation model based on a) advective transport through the transpiration stream, b) retranslocation whereby carbon is expended to resorb nitrogen from leaves, c) active uptake whereby carbon is expended to acquire soil nitrogen, and d) biological nitrogen fixation whereby carbon is expended for symbiotic nitrogen fixers. The model relies on 9 inputs: 1) net primary productivity (NPP), 2) plant C:N ratio, 3) available soil nitrogen, 4) root biomass, 5) transpiration rate, 6) saturated soil depth,7) leaf nitrogen before senescence, 8) soil temperature, and 9) ability to fix nitrogen. A carbon cost of retranslocation is estimated based on leaf nitrogen and compared to an active uptake carbon cost based on root biomass and available soil nitrogen; for nitrogen fixers both costs are compared to a carbon cost of fixation dependent on soil temperature. The NPP is then allocated to optimize growth while maintaining the C:N ratio. The model outputs are total plant nitrogen uptake, remaining NPP available for growth, carbon respired to the soil and updated available soil nitrogen content. We test and validate the model (called FUN: Fixation and Uptake of Nitrogen) against data from the UK, Germany and Peru, and run the model under simplified scenarios of primary succession and climate change. FUN is suitable for incorporation into a land surface scheme of a General Circulation Model and will be coupled with a soil model and dynamic global vegetation model as part of a land surface model (JULES).

  7. Factors affecting the behavior of unburned carbon upon steam activation

    NASA Astrophysics Data System (ADS)

    Lu, Zhe

    The main objective of this study is to investigate the factors that could affect the behavior of unburned carbon samples upon steam activation. Through this work, the relationships among the factors that could influence the carbon-steam reaction with the surface area of the produced activated carbon were explored. Statistical analysis was used to relate the chemical and physical properties of the unburned carbon to the surface area of the activated carbon. Six unburned carbons were selected as feedstocks for activated carbon, and marked as UCA through UCF. The unburned carbons were activated using steam at 850°C for 90 minutes, and the surface areas of their activated counterparts were measured using N2 adsorption isotherms at 77K. The activated carbons produced from different unburned carbon precursors presented different surface areas at similar carbon burn-off levels. Moreover, in different carbon burn-off regions, the sequences for surface area of activated carbons from different unburned carbon samples were different. The factors that may affect the carbon-steam gasification reactions, including the concentration of carbon active sites, the crystallite size of the carbon, the intrinsic porous structure of carbon, and the inorganic impurities, were investigated. All unburned carbons investigated in this study were similar in that they showed the very broad (002) and (10 ) carbon peaks, which are characteristic of highly disordered carbonaceous materials. In this study, the unburned carbon samples contained about 17--48% of inorganic impurities. Compared to coals, the unburned carbon samples contain a larger amount of inorganic impurities as a result of the burn-off, or at lease part, of the carbon during the combustion process. These inorganic particles were divided into two groups in terms of the way they are associated with carbon particles: free single particles, and particles combined with carbon particles. As indicated from the present work, unburned

  8. Phytoplankton productivity, respiration, and nutrient uptake and regeneration in the Potomac River, August 1977 - August 1978

    USGS Publications Warehouse

    Cole, B.E.; Harmon, D.D.

    1981-01-01

    Rates of phytoplankton productivity, respiration, and nutrient uptake and regeneration are presented. These observations were made on the Potomac River estuary (POTE) during four cruises between August 1977 and August 1978. Four experimental methods were used: carbon uptake using carbon-14, carbon uptake and respiration by a pH method, productivity and respiration by the dissolved oxygen method, and nutrient (NH4+, NO3-, NO2-, PO4=, and SiO2=) uptake and regeneration by colorimetry. The experiments were made at sites representative of conditions in four principal reaches of the tidal Potomac River estuary: near the mouth, seaward of the summer nutrient and phytoplankton maximum, near the region of maximum phytoplankton standing stock , and near the maximum anthropogenic nutrient source. (USGS)

  9. Investigating the Formation Mechanisms and Inorganic Precursors of Formate and Acetate in Lost City Hydrothermal Fluids

    NASA Astrophysics Data System (ADS)

    Lang, S. Q.; Bernasconi, S. M.; Früh-Green, G.

    2010-12-01

    Fluids from the Lost City Hydrothermal Field are rich in hydrogen and methane, with high pHs (9 - 11), as a result of serpentinization reactions at moderate temperatures of approximately 120-200°C. It has been predicted that organic carbon compounds would form abiologically under these chemical and thermal conditions from inorganic precursors, in the form of hydrocarbons and organic acids. Previous work has demonstrated the presence of high concentrations of both formate and acetate in the Lost City fluids [Lang et al., 2010, GCA]. Formate is the second most prevalent carbon species in the fluids and may provide local microbial communities with a necessary carbon source in the face of low dissolved inorganic carbon concentrations. The goals of this study are to constrain the formation mechanisms of these organic acids (abiotic vs. biotic) and to identify their inorganic precursors. Formate and acetate were isolated from multiple fluid samples by preparative high-performance liquid chromatography for isotopic analysis. The δ13C of formate is similar to that of Lost City methane, and consistent with an abiological origin. The isotopic signature of acetate is significantly different from these values, and may be indicative of a biological source. Radiocarbon measurements of the isolated formate are in progress and should allow us to determine if the precursor carbon is derived from a mantle or deep-seawater source. Alkaline hydrothermal systems have been proposed as potential sites to the origin of life and formate has been proposed as a critical intermediate towards the kinds of reduced carbon species found in biochemistry. Evidence of an abiological formation mechanism of formate at Lost City may significantly further our understanding of prebiotic chemistry.

  10. Soil Carbon Cycling - More than Changes in Soil Organic Carbon Stocks

    NASA Astrophysics Data System (ADS)

    Lorenz, K.

    2015-12-01

    Discussions about soil carbon (C) sequestration generally focus on changes in soil organic carbon (SOC) stocks. Global SOC mass in the top 1 m was estimated at about 1325 Pg C, and at about 3000 Pg C when deeper soil layers were included. However, both inorganically and organically bound carbon forms are found in soil but estimates on global soil inorganic carbon (SIC) mass are even more uncertain than those for SOC. Globally, about 947 Pg SIC may be stored in the top 1 m, and especially in arid and semi-arid regions SIC stocks can be many times great than SOC stocks. Both SIC and SOC stocks are vulnerable to management practices, and stocks may be enhanced, for example, by optimizing net primary production (NPP) by fertilization and irrigation (especially optimizing belowground NPP for enhancing SOC stocks), adding organic matter (including black C for enhancing SOC stocks), and reducing soil disturbance. Thus, studies on soil C stocks, fluxes, and vulnerability must look at both SIC and SOC stocks in soil profiles to address large scale soil C cycling.

  11. Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing.

    PubMed

    Parazoo, Nicholas C; Arneth, Almut; Pugh, Thomas A M; Smith, Ben; Steiner, Nicholas; Luus, Kristina; Commane, Roisin; Benmergui, Josh; Stofferahn, Eric; Liu, Junjie; Rödenbeck, Christian; Kawa, Randy; Euskirchen, Eugenie; Zona, Donatella; Arndt, Kyle; Oechel, Walt; Miller, Charles

    2018-04-24

    The springtime transition to regional-scale onset of photosynthesis and net ecosystem carbon uptake in boreal and tundra ecosystems are linked to the soil freeze-thaw state. We present evidence from diagnostic and inversion models constrained by satellite fluorescence and airborne CO 2 from 2012 to 2014 indicating the timing and magnitude of spring carbon uptake in Alaska correlates with landscape thaw and ecoregion. Landscape thaw in boreal forests typically occurs in late April (DOY 111 ± 7) with a 29 ± 6 day lag until photosynthetic onset. North Slope tundra thaws 3 weeks later (DOY 133 ± 5) but experiences only a 20 ± 5 day lag until photosynthetic onset. These time lag differences reflect efficient cold season adaptation in tundra shrub and the longer dehardening period for boreal evergreens. Despite the short transition from thaw to photosynthetic onset in tundra, synchrony of tundra respiration with snow melt and landscape thaw delays the transition from net carbon loss (at photosynthetic onset) to net uptake by 13 ± 7 days, thus reducing the tundra net carbon uptake period. Two global CO 2 inversions using a CASA-GFED model prior estimate earlier northern high latitude net carbon uptake compared to our regional inversion, which we attribute to (i) early photosynthetic-onset model prior bias, (ii) inverse method (scaling factor + optimization window), and (iii) sparsity of available Alaskan CO 2 observations. Another global inversion with zero prior estimates the same timing for net carbon uptake as the regional model but smaller seasonal amplitude. The analysis of Alaskan eddy covariance observations confirms regional scale findings for tundra, but indicates that photosynthesis and net carbon uptake occur up to 1 month earlier in evergreens than captured by models or CO 2 inversions, with better correlation to above-freezing air temperature than date of primary thaw. Further collection and analysis of boreal evergreen species over

  12. Using isotopes of dissolved inorganic carbon species and water to separate sources of recharge in a cave spring, northwestern Arkansas, USA Blowing Spring Cave

    USGS Publications Warehouse

    Knierim, Katherine J.; Pollock, Erik; Hays, Phillip D.

    2013-01-01

    Blowing Spring Cave in northwestern Arkansas is representative of cave systems in the karst of the Ozark Plateaus, and stable isotopes of water (δ18O and δ2H) and inorganic carbon (δ13C) were used to quantify soil-water, bedrock-matrix water, and precipitation contributions to cave-spring flow during storm events to understand controls on cave water quality. Water samples from recharge-zone soils and the cave were collected from March to May 2012 to implement a multicomponent hydrograph separation approach using δ18O and δ2H of water and dissolved inorganic carbon (δ13C–DIC). During baseflow, median δ2H and δ18O compositions were –41.6‰ and –6.2‰ for soil water and were –37.2‰ and –5.9‰ for cave water, respectively. Median DIC concentrations for soil and cave waters were 1.8 mg/L and 25.0 mg/L, respectively, and median δ13C–DIC compositions were –19.9‰ and –14.3‰, respectively. During a March storm event, 12.2 cm of precipitation fell over 82 h and discharge increased from 0.01 to 0.59 m3/s. The isotopic composition of precipitation varied throughout the storm event because of rainout, a change of 50‰ and 10‰ for δ2H and δ18O was observed, respectively. Although, at the spring, δ2H and δ18O only changed by approximately 3‰ and 1‰, respectively. The isotopic compositions of precipitation and pre-event (i.e., soil and bedrock matrix) water were isotopically similar and the two-component hydrograph separation was inaccurate, either overestimating (>100%) or underestimating (<0%) the precipitation contribution to the spring. During the storm event, spring DIC and δ13C–DIC decreased to a minimum of 8.6 mg/L and –16.2‰, respectively. If the contribution from precipitation was assumed to be zero, soil water was found to contribute between 23 to 72% of the total volume of discharge. Although the assumption of negligible contributions from precipitation is unrealistic, especially in karst systems where rapid flow

  13. Recent advances in magnetic resonance microscopy to the physical structure characterization of carbonaceous and inorganic materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gregory, D.M.; Gerald, R.E.; Cody, G.D.

    1997-04-01

    Magnetic resonance microscopy (MRM) techniques have been employed to study the molecular architectures and properties of structural polymers, fossil fuels, microporous carbons and inorganic catalysts.

  14. Variable effects of plant colonization on black slate uptake into microbial PLFAs

    NASA Astrophysics Data System (ADS)

    Seifert, Anne-Gret; Trumbore, Susan; Xu, Xiaomei; Zhang, Dachung; Gleixner, Gerd

    2013-04-01

    Microbial degradation of carbon derived from black shale and slate has been shown in vitro. However, in natural settings where other labile carbon sources are likely to exist, this has not been previously demonstrated. We investigated the uptake of ancient carbon derived from slate weathering and from recently photosynthesised organic matter by different groups of microorganisms. Therefore we isolated microbial biomarkers (phospholipid fatty acids, PLFAs) from black slates collected at a chronosequence of waste piles which differed in age and vegetation cover. We quantified the amount of PLFAs and performed stable isotope and radiocarbon measurements on individual or grouped PLFAs to quantify the fraction of slate derived carbon. We used black slate from a pile heaped in the 1950s with either uncovered black slate material (bare site) or material slightly colonized by small plants (greened site) and from a forested leaching pile (forested site) used for alum-mining in the 19th century. Colonization by plants influenced the amount and composition of the microbial community. Greater amounts of PLFAs (5410 ng PLFA/g dw) were extracted from slate sampled at the forested site as opposed to the bare site (960 ng PLFAs/g dw) or the greened (annual grasses and mosses) rock waste pile (1050 ng PLFAs/g dw). We found the highest proportion of PLFAs representing Gram-negative bacteria on the forested site and the highest proportion of PLFAs representing Gram-positive bacteria on the bare site. The fungal PLFA was most abundant at the greened site. Sites with less plant colonization (bare and greened site) tended to have more depleted δ13C values compared to the forested site. Radiocarbon measurements on PLFAs indicated that fungi and Gram-positive bacteria were best adapted to black slate carbon uptake. In the fungal PLFA (combined bare and greened waste pile sample) and in PLFAs of Gram-positive bacteria (greened site) we measured 39.7% and 28.9% ancient carbon uptake

  15. Toward explaining the Holocene carbon dioxide and carbon isotope records: Results from transient ocean carbon cycle-climate simulations

    NASA Astrophysics Data System (ADS)

    Menviel, L.; Joos, F.

    2012-03-01

    The Bern3D model was applied to quantify the mechanisms of carbon cycle changes during the Holocene (last 11,000 years). We rely on scenarios from the literature to prescribe the evolution of shallow water carbonate deposition and of land carbon inventory changes over the glacial termination (18,000 to 11,000 years ago) and the Holocene and modify these scenarios within uncertainties. Model results are consistent with Holocene records of atmospheric CO2 and δ13C as well as the spatiotemporal evolution of δ13C and carbonate ion concentration in the deep sea. Deposition of shallow water carbonate, carbonate compensation of land uptake during the glacial termination, land carbon uptake and release during the Holocene, and the response of the ocean-sediment system to marine changes during the termination contribute roughly equally to the reconstructed late Holocene pCO2 rise of 20 ppmv. The 5 ppmv early Holocene pCO2 decrease reflects terrestrial uptake largely compensated by carbonate deposition and ocean sediment responses. Additional small contributions arise from Holocene changes in sea surface temperature, ocean circulation, and export productivity. The Holocene pCO2 variations result from the subtle balance of forcings and processes acting on different timescales and partly in opposite direction as well as from memory effects associated with changes occurring during the termination. Different interglacial periods with different forcing histories are thus expected to yield different pCO2 evolutions as documented by ice cores.

  16. Cationic carbon quantum dots derived from alginate for gene delivery: One-step synthesis and cellular uptake.

    PubMed

    Zhou, Jie; Deng, Wenwen; Wang, Yan; Cao, Xia; Chen, Jingjing; Wang, Qiang; Xu, Wenqian; Du, Pan; Yu, Qingtong; Chen, Jiaxin; Spector, Myron; Yu, Jiangnan; Xu, Ximing

    2016-09-15

    Carbon quantum dots (CQDs), unlike semiconductor quantum dots, possess fine biocompatibility, excellent upconversion properties, high photostability and low toxicity. Here, we report multifunctional CQDs which were developed using alginate, 3% hydrogen peroxide and double distilled water through a facile, eco-friendly and inexpensive one-step hydrothermal carbonization route. In this reaction, the alginate served as both the carbon source and the cationization agent. The resulting CQDs exhibited strong and stable fluorescence with water-dispersible and positively-charged properties which could serve as an excellent DNA condensation. As non-viral gene vector being used for the first time, the CQDs showed considerably high transfection efficiency (comparable to Lipofectamine2000 and significantly higher than PEI, p<0.05) and negligible toxicity. The photoluminescence properties of CQDs also permitted easy tracking of the cellular-uptake. The findings showed that both caveolae- and clathrin-mediated endocytosis pathways were involved in the internalization process of CQDs/pDNA complexes. Taken together, the alginate-derived photoluminescent CQDs hold great potential in biomedical applications due to their dual role as efficient non-viral gene vectors and bioimaging probes. This manuscript describes a facile and simple one-step hydrothermal carbonization route for preparing optically tunable photoluminescent carbon quantum dots (CQDs) from a novel raw material, alginate. These CQDs enjoy low cytotoxicity, positive zeta potential, excellent ability to condense macromolecular DNA, and most importantly, notably high transfection efficiency. The interesting finding is that the negatively-charged alginate can convert into positively charged CQDs without adding any cationic reagents. The significance of this study is that the cationic carbon quantum dots play dual roles as both non-viral gene vectors and bioimaging probes at the same time, which are most desirable in many

  17. Ammonium and nitrate uptake by leaves of the seagrass Thalassia testudinum: impact of hydrodynamic regime and epiphyte cover on uptake rates

    NASA Astrophysics Data System (ADS)

    Cornelisen, Christopher D.; Thomas, Florence I. M.

    2004-08-01

    Seagrasses rely on the uptake of dissolved inorganic nitrogen (DIN) from both sediment pore water and the water column for metabolic processes. Rates at which their leaves remove nutrients from the water column may be influenced by physiological factors, such as enzyme kinetics, and physical factors, including water flow and the presence of epiphytes on the leaf surface. While there is some evidence of the individual effects of these factors on uptake rates for individual plants, there is little information on the effects of these factors on seagrasses that are situated in their natural environment. In order to isolate the combined effects of water flow and epiphyte cover on uptake rates for Thalassia testudinum leaves while they were situated in a natural canopy we applied 15N-labeled ammonium and 15N-labeled nitrate in a series of field flume experiments. Hydrodynamic parameters related to thickness of diffusive boundary layers, including bottom shear stress and the rate of turbulent energy dissipation, were estimated from velocity profiles collected with an acoustic Doppler velocimeter. Rates of NH 4+ uptake for leaves with and without epiphyte cover were proportional to bottom shear stress and energy dissipation rate, while rates of NO 3- uptake were not. For epiphytes, rates of both NH 4+ and NO 3- uptake were dependent on hydrodynamic parameters. Epiphytes covering the leaf surface reduced rates of NH 4+ uptake for seagrass leaves by an amount proportional to the spatial area covered by the epiphytes (˜90%) and although epiphytes reduced NO 3- uptake rates, the amount was not proportional to the extent of epiphyte cover. Results suggest that the rate at which seagrass leaves removed ammonium was limited by the rate of delivery to the surface of the leaves and was greatly reduced due to blockage of active uptake sites by epiphytes. Conversely, rates of nitrate uptake for the seagrass leaves were limited by the rate at which the leaves could process nitrate

  18. Continuous air agglomeration method for high carbon fly ash beneficiation

    DOEpatents

    Gray, McMahon L.; Champagne, Kenneth J.; Finseth, Dennis H.

    2000-01-01

    The carbon and mineral components of fly ash are effectively separated by a continuous air agglomeration method, resulting in a substantially carboree mineral stream and a highly concentrated carbon product. The method involves mixing the fly ash comprised of carbon and inorganic mineral matter with a liquid hydrocarbon to form a slurry, contacting the slurry with an aqueous solution, dispersing the hydrocarbon slurry into small droplets within the aqueous solution by mechanical mixing and/or aeration, concentrating the inorganic mineral matter in the aqueous solution, agglomerating the carbon and hydrocarbon in the form of droplets, collecting the droplets, separating the hydrocarbon from the concentrated carbon product, and recycling the hydrocarbon.

  19. Distribution of inorganic species in two Antarctic cryptoendolithic microbial communities

    NASA Technical Reports Server (NTRS)

    Johnston, C. G.; Vestal, J. R.; Friedmann, E. I. (Principal Investigator)

    1989-01-01

    Chemical differences were noted between two Antarctic cryptoendolithic (hidden within rock) microenvironments colonized by different microbial communities. Microenvironments dominated by cyanobacteria (BPC) had a higher pH (pH 7-8) than those dominated by lichen (LTL) (pH 4.5-5.5). In order to understand the interactions between the microbiota and the inorganic environment, the inorganic environment was characterized. Water-soluble, carbonate-bound, metal-oxide, organically bound, and residual inorganic species were sequentially extracted from rock samples by chemical means. Each fraction was then quantified using inductively coupled plasma atomic emission spectrometry. BPC contained much more water-soluble and carbonate-bound Ca and Mg than LTL. Metal-oxide species of Al, Fe, and Mn were more abundant in LTL than BPC. Metal oxides appeared to be mobilized (in the order Mn > Fe > Al) from the LTL lichen zone but remained immobile in BPC sandstone. The distribution of K and P bound to metal oxide reflected the distribution of iron oxide in LTL, an indication of the importance of iron in controlling the availability of nutrients in this ecosystem. Metal oxides in turn were likely controlled or influenced by organic matter associated with the lichen community. Despite overall depletion of Fe, Al, and K in the lichen zone, SEM X-ray analysis showed that they were enriched in fungal hyphae. Water-soluble P was present despite the presence of metal oxides, which sequester phosphate. This has biological relevance since P is an essential nutrient.

  20. Cross-ecosystem comparisons of in situ plant uptake of amino acid-N and NH4+

    Treesearch

    Jack W. McFarland; Roger W. Ruess; Knut Kielland; Kurt Pregitzer; Ronald Hendrick; Michael Allen

    2010-01-01

    Plant and microbial use of nitrogen (N) can be simultaneously mutualistic and competitive, particularly in ecosystems dominated by mycorrhizal fungi. Our goal was to quantify plant uptake of organic and inorganic N across a broad latitudinal gradient of forest ecosystems that varied with respect to overstory taxon, edaphic characteristics, and dominant mycorrhizal...

  1. Inorganic nitrogen transformations in the treatment of landfill leachate with a high ammonium load: A case study.

    PubMed

    Parkes, Stephen D; Jolley, Dianne F; Wilson, Stephen R

    2007-01-01

    The inorganic nitrogen transformations occurring at a municipal waste leachate treatment facility were investigated. The treatment facility consisted of a collection well and an artificial wetland between two aeration ponds. The first aeration pond showed a decrease in ammonium (from 3480 (+/- 120) to 630(+/- 90) mg x L(-1)), a reduction in inorganic nitrogen load (3480 to 1680 mg N x L(-1)), and an accumulation of nitrite (< 1.3 mg-N x L(-1) in the collection well, to 1030 mg-N x L(-1)). Incomplete ammonium oxidation was presumably the result of the low concentration of carbonate alkalinity (approximately 2 mg x L(-1)), which may cause a limitation in the ammonium oxidation rate of nitrifiers. Low carbonate alkalinity levels may have been the result of stripping of CO(2) from the first aeration pond at the high aeration rates and low pH. Various chemodenitrification mechanisms are discussed as the reason for the reduction in the inorganic nitrogen load, including; the reduction of nitrite by iron (II) (producing various forms of gaseous nitrogen); and reactions involving nitrous acid. It is suggested that the accumulation of nitrite may be the result of inhibition of nitrite oxidizers by nitrous acid and low temperatures. Relative to the first aeration pond, the speciation and concentration of inorganic nitrogen was stable in the wetlands and 2nd aeration pond. The limited denitrification in the wetlands most probably occurred due to low concentrations of organic carbon, and short retention times.

  2. In situ sensor technology for simultaneous spectrophotometric measurements of seawater total dissolved inorganic carbon and pH.

    PubMed

    Wang, Zhaohui Aleck; Sonnichsen, Frederick N; Bradley, Albert M; Hoering, Katherine A; Lanagan, Thomas M; Chu, Sophie N; Hammar, Terence R; Camilli, Richard

    2015-04-07

    A new, in situ sensing system, Channelized Optical System (CHANOS), was recently developed to make high-resolution, simultaneous measurements of total dissolved inorganic carbon (DIC) and pH in seawater. Measurements made by this single, compact sensor can fully characterize the marine carbonate system. The system has a modular design to accommodate two independent, but similar measurement channels for DIC and pH. Both are based on spectrophotometric detection of hydrogen ion concentrations. The pH channel uses a flow-through, sample-indicator mixing design to achieve near instantaneous measurements. The DIC channel adapts a recently developed spectrophotometric method to achieve flow-through CO2 equilibration between an acidified sample and an indicator solution with a response time of only ∼ 90 s. During laboratory and in situ testing, CHANOS achieved a precision of ±0.0010 and ± 2.5 μmol kg(-1) for pH and DIC, respectively. In situ comparison tests indicated that the accuracies of the pH and DIC channels over a three-week time-series deployment were ± 0.0024 and ± 4.1 μmol kg(-1), respectively. This study demonstrates that CHANOS can make in situ, climatology-quality measurements by measuring two desirable CO2 parameters, and is capable of resolving the CO2 system in dynamic marine environments.

  3. Climate extremes and the carbon cycle.

    PubMed

    Reichstein, Markus; Bahn, Michael; Ciais, Philippe; Frank, Dorothea; Mahecha, Miguel D; Seneviratne, Sonia I; Zscheischler, Jakob; Beer, Christian; Buchmann, Nina; Frank, David C; Papale, Dario; Rammig, Anja; Smith, Pete; Thonicke, Kirsten; van der Velde, Marijn; Vicca, Sara; Walz, Ariane; Wattenbach, Martin

    2013-08-15

    The terrestrial biosphere is a key component of the global carbon cycle and its carbon balance is strongly influenced by climate. Continuing environmental changes are thought to increase global terrestrial carbon uptake. But evidence is mounting that climate extremes such as droughts or storms can lead to a decrease in regional ecosystem carbon stocks and therefore have the potential to negate an expected increase in terrestrial carbon uptake. Here we explore the mechanisms and impacts of climate extremes on the terrestrial carbon cycle, and propose a pathway to improve our understanding of present and future impacts of climate extremes on the terrestrial carbon budget.

  4. A Novel Method for Analysis of Dissolved Inorganic Carbon Concentration and δ13C by Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Smith, E.; Gonneea, M. E.; Boze, L. G.; Casso, M.; Pohlman, J.

    2017-12-01

    Dissolved inorganic carbon (DIC) is the largest pool of carbon in the oceans and is where about half of anthropogenic carbon dioxide (CO2) emissions are being sequestered. Determining the concentration and stable carbon isotopic content (δ13C) of DIC allows us to delineate carbon sources that contribute to marine DIC. A simple and reliable method for measuring DIC concentration and δ13C can be used to apportion contributions from external sources and identify effects from biogeochemical reactions that contribute or remove DIC. The U.S. Geological Survey has developed a discrete sample analysis module (DSAM) that interfaces to a Picarro G-2201i cavity ring-down spectrometer (CRDS, Picarro Inc.) to analyze CO2 and methane concentrations and δ13C from discrete gas samples. In this study, we adapted the USGS DSAM-CRDS analysis system to include an AutoMate prep device (Automate FX, Inc.) for analysis of DIC concentration and δ13C from aqueous samples. The Automate prep device was modified to deliver CO2 extracted from DIC to the DSAM, which conditions and transfers the gas to the CRDS. LabVIEW software (National Instruments) triggers the Automate Prep device, controls the DSAM and collects data from the CRDS. CO2 mass concentration data are obtained by numerical integration of the CO2 volumetric concentrations output by the CRDS and subsequent comparison to standard materials. CO2 carbon isotope values from the CRDS (iCO2) are converted to δ13C values using a slope and offset correction calibration procedure. The system design and operation was optimized using sodium bicarbonate (NaHCO3) standards and a certified reference material. Surface water and pore water samples collected from Sage Lot Pond, a salt marsh in Cape Cod MA, have been analyzed for concentration by coulometry and δ13C by isotope ratio mass spectrometry and will be used to validate the DIC-DSAM-CRDS method for field applications.

  5. Deuterium uptake and sputtering of simultaneous lithiated, boronized, and oxidized carbon surfaces irradiated by low-energy deuterium

    NASA Astrophysics Data System (ADS)

    Domínguez-Gutiérrez, F. J.; Krstić, P. S.; Allain, J. P.; Bedoya, F.; Islam, M. M.; Lotfi, R.; van Duin, A. C. T.

    2018-05-01

    We study the effects of deuterium irradiation on D-uptake by simultaneously boronized, lithiated, oxidized, and deuterated carbon surfaces. We present analysis of the bonding chemistry of D for various concentrations of boron, lithium, oxygen, and deuterium on carbon surfaces using molecular dynamics with reactive force field potentials, which are here adapted to include the interaction of boron and lithium. We calculate D retention and sputtering yields of each constituent of the Li-C-B-O mixture and discuss the role of oxygen in these processes. The extent of the qualitative agreement between new experimental data for B-C-O-D obtained in this paper and computational data is provided. As in the case of the Li-C-O system, comparative studies where experimental and computational data complement each other (in this case on the B-Li-C-O system) provide deeper insights into the mechanisms behind the role that O plays in the retention of D, a relevant issue in fusion machines.

  6. Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification.

    PubMed

    Ow, Yan X; Uthicke, Sven; Collier, Catherine J

    2016-01-01

    Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m(-2) s(-1)) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36-60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA.

  7. Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification

    PubMed Central

    2016-01-01

    Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m-2 s-1) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36–60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA. PMID:26938454

  8. Estimating Particulate Inorganic Carbon Concentrations of the Global Ocean From Ocean Color Measurements Using a Reflectance Difference Approach

    NASA Astrophysics Data System (ADS)

    Mitchell, C.; Hu, C.; Bowler, B.; Drapeau, D.; Balch, W. M.

    2017-11-01

    A new algorithm for estimating particulate inorganic carbon (PIC) concentrations from ocean color measurements is presented. PIC plays an important role in the global carbon cycle through the oceanic carbonate pump, therefore accurate estimations of PIC concentrations from satellite remote sensing are crucial for observing changes on a global scale. An extensive global data set was created from field and satellite observations for investigating the relationship between PIC concentrations and differences in the remote sensing reflectance (Rrs) at green, red, and near-infrared (NIR) wavebands. Three color indices were defined: two as the relative height of Rrs(667) above a baseline running between Rrs(547) and an Rrs in the NIR (either 748 or 869 nm), and one as the difference between Rrs(547) and Rrs(667). All three color indices were found to explain over 90% of the variance in field-measured PIC. But, due to the lack of availability of Rrs(NIR) in the standard ocean color data products, most of the further analysis presented here was done using the color index determined from only two bands. The new two-band color index algorithm was found to retrieve PIC concentrations more accurately than the current standard algorithm used in generating global PIC data products. Application of the new algorithm to satellite imagery showed patterns on the global scale as revealed from field measurements. The new algorithm was more resistant to atmospheric correction errors and residual errors in sun glint corrections, as seen by a reduction in the speckling and patchiness in the satellite-derived PIC images.

  9. Water stable isotope shifts of surface waters as proxies to quantify evaporation, transpiration and carbon uptake on catchment scales

    NASA Astrophysics Data System (ADS)

    Barth, Johannes; van Geldern, Robert; Veizer, Jan; Karim, Ajaz; Freitag, Heiko; Fowlwer, Hayley

    2017-04-01

    Comparison of water stable isotopes of rivers to those of precipitation enables separation of evaporation from transpiration on the catchment scale. The method exploits isotope ratio changes that are caused exclusively by evaporation over longer time periods of at least one hydrological year. When interception is quantified by mapping plant types in catchments, the amount of water lost by transpiration can be determined. When in turn pairing transpiration with the water use efficiency (WUE i.e. water loss by transpiration per uptake of CO2) and subtracting heterotrophic soil respiration fluxes (Rh), catchment-wide carbon balances can be established. This method was applied to several regions including the Great Lakes and the Clyde River Catchments ...(Barth, et al., 2007, Karim, et al., 2008). In these studies evaporation loss was 24 % and 1.3 % and transpiration loss was 47 % and 22 % when compared to incoming precipitation for the Great Lakes and the Clyde Catchment, respectively. Applying WUE values for typical plant covers and using area-typical Rh values led to estimates of CO2 uptake of 251 g C m-2 a-1 for the Great Lakes Catchment and CO2 loss of 21 g C m2 a-1 for the Clyde Catchment. These discrepancies are most likely due to different vegetation covers. The method applies to scales of several thousand km2 and has good potential for improvement via calibration on smaller scales. This can for instance be achieved by separate treatment of sub-catchments with more detailed mapping of interception as a major unknown. These previous studies have shown that better uncertainty analyses are necessary in order to estimate errors in water and carbon balances. The stable isotope method is also a good basis for comparison to other landscape carbon balances for instance by eddy covariance techniques. This independent method and its up-scaling combined with the stable isotope and area-integrating methods can provide cross validation of large-scale carbon budgets

  10. Carbon uptake by mature Amazon forests has mitigated Amazon nations' carbon emissions.

    PubMed

    Phillips, Oliver L; Brienen, Roel J W

    2017-12-01

    Several independent lines of evidence suggest that Amazon forests have provided a significant carbon sink service, and also that the Amazon carbon sink in intact, mature forests may now be threatened as a result of different processes. There has however been no work done to quantify non-land-use-change forest carbon fluxes on a national basis within Amazonia, or to place these national fluxes and their possible changes in the context of the major anthropogenic carbon fluxes in the region. Here we present a first attempt to interpret results from ground-based monitoring of mature forest carbon fluxes in a biogeographically, politically, and temporally differentiated way. Specifically, using results from a large long-term network of forest plots, we estimate the Amazon biomass carbon balance over the last three decades for the different regions and nine nations of Amazonia, and evaluate the magnitude and trajectory of these differentiated balances in relation to major national anthropogenic carbon emissions. The sink of carbon into mature forests has been remarkably geographically ubiquitous across Amazonia, being substantial and persistent in each of the five biogeographic regions within Amazonia. Between 1980 and 2010, it has more than mitigated the fossil fuel emissions of every single national economy, except that of Venezuela. For most nations (Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname) the sink has probably additionally mitigated all anthropogenic carbon emissions due to Amazon deforestation and other land use change. While the sink has weakened in some regions since 2000, our analysis suggests that Amazon nations which are able to conserve large areas of natural and semi-natural landscape still contribute globally-significant carbon sequestration. Mature forests across all of Amazonia have contributed significantly to mitigating climate change for decades. Yet Amazon nations have not directly benefited from providing this global scale

  11. The first true inorganic fullerenes?

    NASA Astrophysics Data System (ADS)

    Parilla, P. A.; Dillon, A. C.; Jones, K. M.; Riker, G.; Schulz, D. L.; Ginley, D. S.; Heben, M. J.

    1999-01-01

    Boron nitride and materials of composition MX2, where M is molybdenum or tungsten and X is sulphur or selenium, can form fullerene-like structures such as nested polyhedra or nanotubes. However, the analogy to the carbon fullerene family falls short because no small preferred structure akin to C60(ref. 5) has been found. We have discovered nano-octahedra of MoS2of discrete sizes in soots that we prepared by laser ablation of pressed MoS2targets. These nano-octahedra are much larger than C60structures, having edge lengths of about 4.0 and 5.0 nanometres, and may represent the first `inorganic fullerenes'.

  12. Simple global carbon model: The atmosphere-terrestrial biosphere-ocean interaction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kwon, O.Y.; Schnoor, J.L.

    A simple global carbon model has been developed for scenario analysis, and research needs prioritization. CO{sub 2} fertilization and temperature effects are included in the terrestrial biosphere compartment, and the ocean compartment includes inorganic chemistry which, with ocean water circulation, enables the calculation of time-variable oceanic carbon uptake. Model-derived Q{sub 10} values (the increasing rate for every 10{degrees}C increase of temperature) are 1.37 for land biota photosynthesis, 1.89 for land biota respiration, and 1.95 for soil respiration, and feedback temperature is set at 0.01{degrees}C/ppm of CO{sub 2}. These could be the important parameters controlling the carbon cycle in potential globalmore » warming scenarios. Scenario analysis, together with sensitivity analysis of temperature feedback, suggests that if CO{sub 2} emissions from fossil fuel combustion continue at the present increasing rate of {approximately}1.5% per year, a CO{sub 2} doubling (to 560 ppm) will appear in year 2060. Global warming would be responsible for 40 Gt as carbon (Gt C) accumulation in the land biota, 88 Gt C depletion from the soil carbon, a 7 Gt C accumulation in the oceans, and a 19 ppm increase in atmospheric CO{sub 2}. The ocean buffering capacity to take up the excess CO{sub 2} will decrease with the increasing atmospheric CO{sub 2} concentration. 51 refs., 8 figs., 3 tabs.« less

  13. Selenium Uptake and Volatilization by Marine Algae

    NASA Astrophysics Data System (ADS)

    Luxem, Katja E.; Vriens, Bas; Wagner, Bettina; Behra, Renata; Winkel, Lenny H. E.

    2015-04-01

    Selenium (Se) is an essential trace nutrient for humans. An estimated one half to one billion people worldwide suffer from Se deficiency, which is due to low concentrations and bioavailability of Se in soils where crops are grown. It has been hypothesized that more than half of the atmospheric Se deposition to soils is derived from the marine system, where microorganisms methylate and volatilize Se. Based on model results from the late 1980s, the atmospheric flux of these biogenic volatile Se compounds is around 9 Gt/year, with two thirds coming from the marine biosphere. Algae, fungi, and bacteria are known to methylate Se. Although algal Se uptake, metabolism, and methylation influence the speciation and bioavailability of Se in the oceans, these processes have not been quantified under environmentally relevant conditions and are likely to differ among organisms. Therefore, we are investigating the uptake and methylation of the two main inorganic Se species (selenate and selenite) by three globally relevant microalgae: Phaeocystis globosa, the coccolithophorid Emiliania huxleyi, and the diatom Thalassiosira oceanica. Selenium uptake and methylation were quantified in a batch experiment, where parallel gas-tight microcosms in a climate chamber were coupled to a gas-trapping system. For E. huxleyi, selenite uptake was strongly dependent on aqueous phosphate concentrations, which agrees with prior evidence that selenite uptake by phosphate transporters is a significant Se source for marine algae. Selenate uptake was much lower than selenite uptake. The most important volatile Se compounds produced were dimethyl selenide, dimethyl diselenide, and dimethyl selenyl sulfide. Production rates of volatile Se species were larger with increasing intracellular Se concentration and in the decline phase of the alga. Similar experiments are being carried out with P. globosa and T. oceanica. Our results indicate that marine algae are important for the global cycling of Se

  14. Carbon speciation and surface tension of fog

    USGS Publications Warehouse

    Capel, P.D.; Gunde, R.; Zurcher, F.; Giger, W.

    1990-01-01

    The speciation of carbon (dissolved/particulate, organic/inorganic) and surface tension of a number of radiation fogs from the urban area of Zurich, Switzerland, were measured. The carbon species were dominated by "dissolved" organic carbon (DOC; i.e., the fraction that passes through a filter), which was typically present at levels of 40-200 mg/L. Less than 10% of the DOC was identified as specific individual organic compounds. Particulate organic carbon (POC) accounted for 26-41% of the mass of the particles, but usually less than 10% of the total organic carbon mass. Inorganic carbon species were relatively minor. The surface tensions of all the measured samples were less than pure water and were correlated with their DOC concentrations. The combination of high DOC and POC and low surface tension suggests a mechanism for the concentration of hydrophobic organic contaminants in the fog droplet, which have been observed by numerous investigators. ?? 1990 American Chemical Society.

  15. Expanding the analyte set of the JPL Electronic Nose to include inorganic compounds

    NASA Technical Reports Server (NTRS)

    Ryan, M. A.; Homer, M. L.; Zhou, H.; Mannat, K.; Manfreda, A.; Kisor, A.; Shevade, A.; Yen, S. P. S.

    2005-01-01

    An array-based sensing system based on 32 polymer/carbon composite conductometric sensors is under development at JPL. Until the present phase of development, the analyte set has focuses on organic compounds and a few selected inorganic compounds, notably ammonia and hydrazine.

  16. Light intensity affects the uptake and metabolism of glycine by pakchoi (Brassica chinensis L.)

    NASA Astrophysics Data System (ADS)

    Ma, Qingxu; Cao, Xiaochuang; Wu, Lianghuan; Mi, Wenhai; Feng, Ying

    2016-02-01

    The uptake of glycine by pakchoi (Brassica chinensis L.), when supplied as single N-source or in a mixture of glycine and inorganic N, was studied at different light intensities under sterile conditions. At the optimal intensity (414 μmol m-2 s-1) for plant growth, glycine, nitrate, and ammonium contributed 29.4%, 39.5%, and 31.1% shoot N, respectively, and light intensity altered the preferential absorption of N sources. The lower 15N-nitrate in root but higher in shoot and the higher 15N-glycine in root but lower in shoot suggested that most 15N-nitrate uptake by root transported to shoot rapidly, with the shoot being important for nitrate assimilation, and the N contribution of glycine was limited by post-uptake metabolism. The amount of glycine that was taken up by the plant was likely limited by root uptake at low light intensities and by the metabolism of ammonium produced by glycine at high light intensities. These results indicate that pakchoi has the ability to uptake a large quantity of glycine, but that uptake is strongly regulated by light intensity, with metabolism in the root inhibiting its N contribution.

  17. Needle age and season influence photosynthetic temperature response and total annual carbon uptake in mature Picea mariana trees

    DOE PAGES

    Jensen, Anna M.; Warren, Jeffrey; Hanson, Paul J.; ...

    2015-01-01

    Using seasonal- and cohort-specific photosynthetic temperature response functions, we quantified the physiological significance of maintaining multiple foliar cohorts in mature (~40-45 year old) Picea mariana trees in an ombrotrophic Sphagnum-bog, northern Minnesota, USA. We measured photosynthetic capacity, foliar respiration (Rd), biochemistry and morphology to estimate annual carbon (C) uptake by cohort, season and canopy position. Temperature response of key photosynthetic parameters at 25 C (i.e., light-saturated rate of CO 2 assimilation (Asat), light-saturated rate of Rubisco carboxylation (Vcmax), light-saturated electron transport rate (Jmax)) were clearly dependent on season and were generally less responsive in younger needles. Temperature optimums range betweenmore » 18.7-23.7, 31.3-38.3 and 28.7-36.7 C for Asat, Vcmax and Jmax respectively. Current-year (Y0) foliage had lower photosynthetic capacities compared to one-year-old (Y1) and two-year-old (Y2) foliage. As Y0 needles matured, values of Asat, Vcmax, Jmax, foliar LMA and nitrogen increased. Values of Vcmax, Jmax and Rd were related to foliar nitrogen but only in the youngest (Y0) cohort. Foliar ontogeny affected photosynthetic capacity more than growth temperature. Morphological and physiological cohort differences were reflected by their annual contribution to modeled C uptake, with a ~36% lower estimated annual C uptake by Y0 needles (LAI 0.52 m 2m -2) compared to Y1&2 cohorts (LAI 0.67 m 2m -2). Collectively, these results illustrate the physiological and ecological significance of characterizing multiple foliar cohorts during bud break and throughout the growth season, and for cumulative C uptake model estimates.« less

  18. Enhancing cell growth and lutein productivity of Desmodesmus sp. F51 by optimal utilization of inorganic carbon sources and ammonium salt.

    PubMed

    Xie, Youping; Zhao, Xurui; Chen, Jianfeng; Yang, Xuqiu; Ho, Shih-Hsin; Wang, Baobei; Chang, Jo-Shu; Shen, Ying

    2017-11-01

    The type and concentration of inorganic carbon and nitrogen sources were manipulated to improve cell growth and lutein productivity of Desmodesmus sp. F51. Using nitrate as nitrogen source, the better cell growth and lutein accumulation were obtained under 2.5% CO 2 supply when compared to the addition of NaHCO 3 or Na 2 CO 3 . To solve the pH variation problem of ammonium consumption, the strategy of using dual carbon sources (NaHCO 3 and CO 2 ) was explored. A lower bicarbonate-C: ammonium-N ratio led to a lower culture pH as well as lower lutein productivity, but significantly enhanced the auto-flocculation efficiency of the microalgal cells. The highest biomass productivity (939mg/L/d) and lutein productivity (5.22mg/L/d) were obtained when the bicarbonate-C/ammonium-N ratio and ammonium-N concentration were 1:1 and 150mg/L, respectively. The lutein productivity of 5.22mg/L/d is the highest value ever reported in the literature using batch phototrophic cultivation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. An oil-based model of inhalation anesthetic uptake and elimination.

    PubMed

    Loughlin, P J; Bowes, W A; Westenskow, D R

    1989-08-01

    An oil-based model was developed as a physical simulation of inhalation anesthetic uptake and elimination. It provides an alternative to animal models in testing the performance of anesthesia equipment. A 7.5-1 water-filled manometer simulates pulmonary mechanics. Nitrogen and carbon dioxide flowing into the manometer simulate oxygen consumption and carbon dioxide production. Oil-filled chambers (180 ml and 900 ml) simulate the uptake and washout of halothane by the vessel-rich and muscle tissue groups. A 17.2-1 air-filled chamber simulates uptake by the lung group. Gas circulates through the chambers (3.7, 13.8, and 25 l/min) to simulate the transport of anesthetic to the tissues by the circulatory system. Results show that during induction and washout, the rate of rise in endtidal halothane fraction simulated by the model parallels that measured in patients. The model's end-tidal fraction changes correctly with changes in cardiac output and alveolar ventilation. The model has been used to test anesthetic controllers and to evaluate gas sensors, and should be useful in teaching principles underlying volatile anesthetic uptake.

  20. Needle age and season influence photosynthetic temperature response and total annual carbon uptake in mature Picea mariana trees

    PubMed Central

    Jensen, Anna M.; Warren, Jeffrey M.; Hanson, Paul J.; Childs, Joanne; Wullschleger, Stan D.

    2015-01-01

    Background and Aims The carbon (C) balance of boreal terrestrial ecosystems is sensitive to increasing temperature, but the direction and thresholds of responses are uncertain. Annual C uptake in Picea and other evergreen boreal conifers is dependent on seasonal- and cohort-specific photosynthetic and respiratory temperature response functions, so this study examined the physiological significance of maintaining multiple foliar cohorts for Picea mariana trees within an ombrotrophic bog ecosystem in Minnesota, USA. Methods Measurements were taken on multiple cohorts of needles for photosynthetic capacity, foliar respiration (Rd) and leaf biochemistry and morphology of mature trees from April to October over 4 years. The results were applied to a simple model of canopy photosynthesis in order to simulate annual C uptake by cohort age under ambient and elevated temperature scenarios. Key Results Temperature responses of key photosynthetic parameters [i.e. light-saturated rate of CO2 assimilation (Asat), rate of Rubisco carboxylation (Vcmax) and electron transport rate (Jmax)] were dependent on season and generally less responsive in the developing current-year (Y0) needles compared with 1-year-old (Y1) or 2-year-old (Y2) foliage. Temperature optimums ranged from 18·7 to 23·7, 31·3 to 38·3 and 28·7 to 36·7 °C for Asat, Vcmax and Jmax, respectively. Foliar cohorts differed in their morphology and photosynthetic capacity, which resulted in 64 % of modelled annual stand C uptake from Y1&2 cohorts (LAI 0·67 m2 m−2) and just 36 % from Y0 cohorts (LAI 0·52 m2 m−2). Under warmer climate change scenarios, the contribution of Y0 cohorts was even less; e.g. 31 % of annual C uptake for a modelled 9 °C rise in mean summer temperatures. Results suggest that net annual C uptake by P. mariana could increase under elevated temperature, and become more dependent on older foliar cohorts. Conclusions Collectively, this study illustrates the physiological and

  1. Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

    NASA Astrophysics Data System (ADS)

    Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

    2015-10-01

    ;Clumped-isotope; thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope ;clumps;). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals. We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect. Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3- and CO32-. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many natural systems. The two

  2. Beyond temperature: Clumped isotope signatures in dissolved inorganic carbon species and the influence of solution chemistry on carbonate mineral composition

    USGS Publications Warehouse

    Tripati, Aradhna K.; Hill, Pamela S.; Eagle, Robert A.; Mosenfelder, Jed L.; Tang, Jianwu; Schauble, Edwin A.; Eiler, John M.; Zeebe, Richard E.; Uchikawa, Joji; Coplen, Tyler B.; Ries, Justin B.; Henry, Drew

    2015-01-01

    “Clumped-isotope” thermometry is an emerging tool to probe the temperature history of surface and subsurface environments based on measurements of the proportion of 13C and 18O isotopes bound to each other within carbonate minerals in 13C18O16O22- groups (heavy isotope “clumps”). Although most clumped isotope geothermometry implicitly presumes carbonate crystals have attained lattice equilibrium (i.e., thermodynamic equilibrium for a mineral, which is independent of solution chemistry), several factors other than temperature, including dissolved inorganic carbon (DIC) speciation may influence mineral isotopic signatures. Therefore we used a combination of approaches to understand the potential influence of different variables on the clumped isotope (and oxygen isotope) composition of minerals.We conducted witherite precipitation experiments at a single temperature and at varied pH to empirically determine 13C-18O bond ordering (Δ47) and δ18O of CO32- and HCO3- molecules at a 25 °C equilibrium. Ab initio cluster models based on density functional theory were used to predict equilibrium 13C-18O bond abundances and δ18O of different DIC species and minerals as a function of temperature. Experiments and theory indicate Δ47 and δ18O compositions of CO32- and HCO3- ions are significantly different from each other. Experiments constrain the Δ47-δ18O slope for a pH effect (0.011 ± 0.001; 12 ⩾ pH ⩾ 7). Rapidly-growing temperate corals exhibit disequilibrium mineral isotopic signatures with a Δ47-δ18O slope of 0.011 ± 0.003, consistent with a pH effect.Our theoretical calculations for carbonate minerals indicate equilibrium lattice calcite values for Δ47 and δ18O are intermediate between HCO3− and CO32−. We analyzed synthetic calcites grown at temperatures ranging from 0.5 to 50 °C with and without the enzyme carbonic anhydrase present. This enzyme catalyzes oxygen isotopic exchange between DIC species and is present in many

  3. Transport and Fate of Organic and Inorganic Nitrogen from Biosolids leachates

    NASA Astrophysics Data System (ADS)

    Ilani, Talli; Trifonov, Pavel; Arye, Gilboa

    2014-05-01

    The use of biosolids as a means to ameliorate soil becomes prevalent in the last few years. In agricultural fields, the application of biosolids will be followed by irrigation; resulting in excessive leaching of the dissolved fraction of the organic matter. The dissolved organic matter (DOM) is one of the major players in the chemical, physical and biological processes in soils. The DOM mainly composed of dissolved organic carbon (DOC) and lower proportions of dissolved organic nitrogen (DON) and phosphate (DOP). The DON is considered to be the primary source of mineralisable nitrogen in the soil and can be used as an estimate of the nitrogen supplying capacity of the organic matter. Most of the researches which are dealing with nitrogen fate in terrestrial environments focused on its inorganic fractions (mainly nitrate and ammonium) and their transport toward the dipper soil layers. Since DON can be the source of the inorganic nitrogen (by providing nutrients and energy to nitrifying microbes, which in turn increases the nitrogen source for plants as nitrate), knowledge about the nature of its transport characteristics in the soil is important in the case of biosolids amendment. In addition, irrigation water quality (e.g. fresh water, wastewater or desalinized water) may significantly affect the transport and fate of the various nitrogen forms. The main objective of this study is to examine the fate and co-transport of organic and inorganics nitrogen, originating from biosolids leachates in the subsoil. The effect of water quality and flow rate under saturated steady-state flow is examined by a series of flow-through soil column experiments. The established breakthrough curves of the co-transport of total nitrogen, organic nitrogen (will be calculated from the differences between the total nitrogen measurements and the inorganic nitrogen measurements), nitrate, ammonium, dissolved organic carbon and chloride is presented and discussed.

  4. Inorganic nanostructured materials for high performance electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Liu, Sheng; Sun, Shouheng; You, Xiao-Zeng

    2014-01-01

    Electrochemical supercapacitors (ES) are a well-known energy storage system that has high power density, long life-cycle and fast charge-discharge kinetics. Nanostructured materials are a new generation of electrode materials with large surface area and short transport/diffusion path for ions and electrons to achieve high specific capacitance in ES. This mini review highlights recent developments of inorganic nanostructure materials, including carbon nanomaterials, metal oxide nanoparticles, and metal oxide nanowires/nanotubes, for high performance ES applications.

  5. Inorganic nanostructured materials for high performance electrochemical supercapacitors.

    PubMed

    Liu, Sheng; Sun, Shouheng; You, Xiao-Zeng

    2014-02-21

    Electrochemical supercapacitors (ES) are a well-known energy storage system that has high power density, long life-cycle and fast charge-discharge kinetics. Nanostructured materials are a new generation of electrode materials with large surface area and short transport/diffusion path for ions and electrons to achieve high specific capacitance in ES. This mini review highlights recent developments of inorganic nanostructure materials, including carbon nanomaterials, metal oxide nanoparticles, and metal oxide nanowires/nanotubes, for high performance ES applications.

  6. Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake.

    PubMed

    Miralles, Pola; Johnson, Errin; Church, Tamara L; Harris, Andrew T

    2012-12-07

    Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l(-1) CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe(3)O(4)-functionalized CNTs were prepared and studied using energy-filter mapping of Fe(3)O(4). CNTs bearing Fe(3)O(4) nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up.

  7. Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake

    PubMed Central

    Miralles, Pola; Johnson, Errin; Church, Tamara L.; Harris, Andrew T.

    2012-01-01

    Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l−1 CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe3O4-functionalized CNTs were prepared and studied using energy-filter mapping of Fe3O4. CNTs bearing Fe3O4 nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up. PMID:22977097

  8. Greater deciduous shrub abundance extends tundra peak season and increases modeled net CO2 uptake.

    PubMed

    Sweet, Shannan K; Griffin, Kevin L; Steltzer, Heidi; Gough, Laura; Boelman, Natalie T

    2015-06-01

    Satellite studies of the terrestrial Arctic report increased summer greening and longer overall growing and peak seasons since the 1980s, which increases productivity and the period of carbon uptake. These trends are attributed to increasing air temperatures and reduced snow cover duration in spring and fall. Concurrently, deciduous shrubs are becoming increasingly abundant in tundra landscapes, which may also impact canopy phenology and productivity. Our aim was to determine the influence of greater deciduous shrub abundance on tundra canopy phenology and subsequent impacts on net ecosystem carbon exchange (NEE) during the growing and peak seasons in the arctic foothills region of Alaska. We compared deciduous shrub-dominated and evergreen/graminoid-dominated community-level canopy phenology throughout the growing season using the normalized difference vegetation index (NDVI). We used a tundra plant-community-specific leaf area index (LAI) model to estimate LAI throughout the green season and a tundra-specific NEE model to estimate the impact of greater deciduous shrub abundance and associated shifts in both leaf area and canopy phenology on tundra carbon flux. We found that deciduous shrub canopies reached the onset of peak greenness 13 days earlier and the onset of senescence 3 days earlier compared to evergreen/graminoid canopies, resulting in a 10-day extension of the peak season. The combined effect of the longer peak season and greater leaf area of deciduous shrub canopies almost tripled the modeled net carbon uptake of deciduous shrub communities compared to evergreen/graminoid communities, while the longer peak season alone resulted in 84% greater carbon uptake in deciduous shrub communities. These results suggest that greater deciduous shrub abundance increases carbon uptake not only due to greater leaf area, but also due to an extension of the period of peak greenness, which extends the period of maximum carbon uptake. © 2015 John Wiley & Sons Ltd.

  9. Nitrogen fertilization raises CO2 efflux from inorganic carbon: A global assessment.

    PubMed

    Zamanian, Kazem; Zarebanadkouki, Mohsen; Kuzyakov, Yakov

    2018-07-01

    Nitrogen (N) fertilization is an indispensable agricultural practice worldwide, serving the survival of half of the global population. Nitrogen transformation (e.g., nitrification) in soil as well as plant N uptake releases protons and increases soil acidification. Neutralizing this acidity in carbonate-containing soils (7.49 × 10 9  ha; ca. 54% of the global land surface area) leads to a CO 2 release corresponding to 0.21 kg C per kg of applied N. We here for the first time raise this problem of acidification of carbonate-containing soils and assess the global CO 2 release from pedogenic and geogenic carbonates in the upper 1 m soil depth. Based on a global N-fertilization map and the distribution of soils containing CaCO 3 , we calculated the CO 2 amount released annually from the acidification of such soils to be 7.48 × 10 12  g C/year. This level of continuous CO 2 release will remain constant at least until soils are fertilized by N. Moreover, we estimated that about 273 × 10 12  g CO 2 -C are released annually in the same process of CaCO 3 neutralization but involving liming of acid soils. These two CO 2 sources correspond to 3% of global CO 2 emissions by fossil fuel combustion or 30% of CO 2 by land-use changes. Importantly, the duration of CO 2 release after land-use changes usually lasts only 1-3 decades before a new C equilibrium is reached in soil. In contrast, the CO 2 released by CaCO 3 acidification cannot reach equilibrium, as long as N fertilizer is applied until it becomes completely neutralized. As the CaCO 3 amounts in soils, if present, are nearly unlimited, their complete dissolution and CO 2 release will take centuries or even millennia. This emphasizes the necessity of preventing soil acidification in N-fertilized soils as an effective strategy to inhibit millennia of CO 2 efflux to the atmosphere. Hence, N fertilization should be strictly calculated based on plant-demand, and overfertilization should be avoided not only

  10. Uptake of atmospheric carbon dioxide into silk fiber by silkworms.

    PubMed

    Magoshi, Jun; Tanaka, Toshihisa; Sasaki, Haruto; Kobayashi, Masatoshi; Magoshi, Yoshiko; Tsuda, Hidetoshi; Becker, Mary A; Inoue, Shun-ichi; Ishimaru, Ken

    2003-01-01

    The relation between the uptake of atmospheric CO(2) and insect's production of silk fiber has not yet been reported. Here, we provide the first quantitative demonstrations that four species of silkworms (Bombyx mori, Samia cynthia ricini, Antheraea pernyi, and Antheraea yamamai) and a silk-producing spider (Nephila clavata) incorporate atmospheric CO(2) into their silk fibers. The abundance of (13)C incorporated from the environment was determined by mass spectrometry and (13)C NMR measurements. Atmospheric CO(2) was incorporated into the silk fibers in the carbonyl groups of alanine, aspartic acid, serine, and glycine and the C(gamma) of aspartic acid. We show a simple model for the uptake of atmospheric CO(2) by silkworms. These results will demonstrate that silkworm has incorporated atmospheric CO(2) into silk fiber via the TCA cycle; however, the magnitude of uptake into the silk fibers is smaller than that consumed by the photosynthesis in trees and coral reefs.

  11. Elevated CO2 plus chronic warming reduce nitrogen uptake and levels or activities of nitrogen-uptake and -assimilatory proteins in tomato roots.

    PubMed

    Jayawardena, Dileepa M; Heckathorn, Scott A; Bista, Deepesh R; Mishra, Sasmita; Boldt, Jennifer K; Krause, Charles R

    2017-03-01

    Atmospheric CO 2 enrichment is expected to often benefit plant growth, despite causing global warming and nitrogen (N) dilution in plants. Most plants primarily procure N as inorganic nitrate (NO 3 - ) or ammonium (NH 4 + ), using membrane-localized transport proteins in roots, which are key targets for improving N use. Although interactive effects of elevated CO 2 , chronic warming and N form on N relations are expected, these have not been studied. In this study, tomato (Solanum lycopersicum) plants were grown at two levels of CO 2 (400 or 700 ppm) and two temperature regimes (30 or 37°C), with NO 3 - or NH 4 + as the N source. Elevated CO 2 plus chronic warming severely inhibited plant growth, regardless of N form, while individually they had smaller effects on growth. Although %N in roots was similar among all treatments, elevated CO 2 plus warming decreased (1) N-uptake rate by roots, (2) total protein concentration in roots, indicating an inhibition of N assimilation and (3) shoot %N, indicating a potential inhibition of N translocation from roots to shoots. Under elevated CO 2 plus warming, reduced NO 3 - -uptake rate per g root was correlated with a decrease in the concentration of NO 3 - -uptake proteins per g root, reduced NH 4 + uptake was correlated with decreased activity of NH 4 + -uptake proteins and reduced N assimilation was correlated with decreased concentration of N-assimilatory proteins. These results indicate that elevated CO 2 and chronic warming can act synergistically to decrease plant N uptake and assimilation; hence, future global warming may decrease both plant growth and food quality (%N). © 2016 Scandinavian Plant Physiology Society.

  12. The Effect of Organic Compounds on the Hygroscopic Properties of Inorganic Aerosol

    NASA Astrophysics Data System (ADS)

    Krieger, U. K.; Zardini, A. A.; Marcolli, C.

    2006-12-01

    The hygroscopicity of the aerosols plays a major role for the direct and indirect effect on the climate. It is known that aerosols are often a mixture of inorganic and organic matter. A significant fraction of the organic matter is water soluble (WSOC) and affects light scattering, water uptake and phase transitions of multicomponent aerosols. Additionally, organic matter can act as a surfactant around an inorganic particle, affecting the evaporation-condensation time scale. This research project benefits from the combined measurements performed by two different instrumentations: the electrodynamic trap at IACETH, Zürich, Switzerland, and a Tandem Differential Mobility Analizer (TDMA) at the Paul Scherrer Institute, Switzerland. The Electrodynamic Trap consists of a chamber in which a levitated particle can experience all the atmospherically relevant conditions of temperature, pressure, and humidity. All these parameters can be continuously varied so that the hygroscopic curve of the aerosol particle can be measured. Additional tools help to better characterize the aerosol particle: 90 degrees angular scattering of lasers (for radius measurements) and intensity fluctuation of the scattered light with time (for phase changes detection). In this poster the results obtained through the electrodynamic balance technique will be shown and compared with the TDMA. In particular, bicomponent ammonium sulphate with adipic acid bicomponent particles are studied, with different mixing ratios. Particular emphasis is put on assessing the water uptake and the phase changes of the particles.

  13. Plant Nitrogen Uptake in Terrestrial Biogeochemical Models

    NASA Astrophysics Data System (ADS)

    Marti Donati, A.; Cox, P.; Smith, M. J.; Purves, D.; Sitch, S.; Jones, C. D.

    2013-12-01

    Most terrestrial biogeochemical models featured in the last Intergovernmental Panel on Climate Change (IPPC) Assessment Report highlight the importance of the terrestrial Carbon sequestration and feedbacks between the terrestrial Carbon cycle and the climate system. However, these models have been criticized for overestimating predicted Carbon sequestration and its potential climate feedback when calculating the rate of future climate change because they do not account for the Carbon sequestration constraints caused by nutrient limitation, particularly Nitrogen (N). This is particularly relevant considering the existence of a substantial deficit of Nitrogen for plants in most areas of the world. To date, most climate models assume that plants have access to as much Nitrogen as needed, but ignore the nutrient requirements for new vegetation growth. Determining the natural demand and acquisition for Nitrogen and its associated resource optimization is key when accounting for the Carbon sequestration constrains caused by nutrient limitation. The few climate models that include C-N dynamics have illustrated that the stimulation of plant growth over the coming century may be significantly smaller than previously predicted. However, models exhibit wide differences in their predictive accuracy and lead to widely diverging and inconsistent projections accounting for an uncertain Carbon sequestration decrease due to Nitrogen limitation ranging from 7 to 64%. This reduction in growth is partially offset by an increase in the availability of nutrients resulting from an accelerated rate of decomposition of dead plants and other organic matter that occurring with a rise in temperature. However, this offset does not counterbalance the reduced level of plant growth calculated by natural nutrient limitations. Additionally, Nitrogen limitation is also expected to become more pronounced in some ecosystems as atmospheric CO2 concentration increases; resulting in less new growth and

  14. In vitro erythemal UV-A protection factors of inorganic sunscreens distributed in aqueous media using carnauba wax-decyl oleate nanoparticles.

    PubMed

    Villalobos-Hernández, J R; Müller-Goymann, C C

    2007-01-01

    This paper describes the in vitro photoprotection in the UV-A range, i.e. 320-400 nm obtained by the use of carnauba wax-decyl oleate nanoparticles either as encapsulation systems or as accompanying vehicles for inorganic sunscreens such as barium sulfate, strontium carbonate and titanium dioxide. Lipid-free inorganic sunscreen nanosuspensions, inorganic sunscreen-free wax-oil nanoparticle suspensions and wax-oil nanoparticle suspensions containing inorganic sunscreens dispersed either in their oil phase or their aqueous phase were prepared by high pressure homogenization. The in vitro erythemal UV-A protection factors (EUV-A PFs) of the nanosuspensions were calculated by means of a sun protection analyzer. EUV-A PFs being no higher than 4 were obtained by the encapsulation of barium sulfate and strontium carbonate, meanwhile by the distribution of titanium dioxide in presence of wax-oil nanoparticles, the EUV-A PFs varied between 2 and 19. The increase in the EUV-A PFs of the titanium dioxide obtained by the use of wax-oil nanoparticles demonstrated a better performance of the sun protection properties of this pigment in the UV-A region.

  15. Organic and Inorganic Matter in Louisiana Coastal Waters: Vermilion, Atchafalaya, Terrebonne, Barataria, and Mississippi Regions.

    EPA Science Inventory

    Chromophoric dissolved organic matter (CDOM) spectral absorption, dissolved organic carbon (DOC) concentration, and the particulate fraction of inorganic (PIM) and organic matter (POM) were measured in Louisiana coastal waters at Vermilion, Atchafalaya, Terrebonne, Barataria, and...

  16. Biosynthetic inorganic chemistry.

    PubMed

    Lu, Yi

    2006-08-25

    Inorganic chemistry and biology can benefit greatly from each other. Although synthetic and physical inorganic chemistry have been greatly successful in clarifying the role of metal ions in biological systems, the time may now be right to utilize biological systems to advance coordination chemistry. One such example is the use of small, stable, easy-to-make, and well-characterized proteins as ligands to synthesize novel inorganic compounds. This biosynthetic inorganic chemistry is possible thanks to a number of developments in biology. This review summarizes the progress in the synthesis of close models of complex metalloproteins, followed by a description of recent advances in using the approach for making novel compounds that are unprecedented in either inorganic chemistry or biology. The focus is mainly on synthetic "tricks" learned from biology, as well as novel structures and insights obtained. The advantages and disadvantages of this biosynthetic approach are discussed.

  17. Influence of food, aquatic humus, and alkalinity on methylmercury uptake by Daphnia magna

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Monson, B.A.; Brezonik, P.L.

    Six-day-old Daphnia magna were exposed to low concentrations of methylmercury (MeHg) in synthetic freshwater and synthetic food. Uptake kinetics were determined in 24- to 72-h experiments, measuring both the loss of Hg from water and accumulation in D. magna. Dose-uptake response was linear for MeHg concentrations up to 4.0 ng/L; an initial concentration of 2.0 ng/L was used when other factors were varied. Concentrations of total Hg and MeHg in water and D. magna were measured in treatments with varied hardness and alkalinity, aquatic humus (AH), and food spiked with MeHg versus water spiked with MeHg. Uptake rate coefficients weremore » derived from two versions of a first-order, two-compartment model. The first version assumed constant MeHg concentration; the second accounted for changing MeHg concentration in water over time. Both models accounted for a nonzero starting concentration of MeHg in plankton. Fitted rate coefficients were higher for the second model than the first: the uptake coefficient (k{sub u}) was nine times higher; the depuration coefficient (k{sub d}) was twice as high. Assuming a constant MeHg concentration for a one-time spike thus underestimated the rate coefficient. The source of MeHg was compared by exposing D. magna for 48 h to MeHg at 2 ng/L in food or water. Daphnia magna accumulated significantly more inorganic Hg (i.e., Hg{sup 2+}) from spiked food than from spiked water, but accumulation of MeHg was the same from both sources. A similar response was found when D. magna were exposed to a lake water extraction of AH at concentrations of C at 3 and 10 mg/L. At the higher AH concentration, total Hg in daphnids was higher, but MeHg was lower, suggesting that AH was a source of inorganic Hg but reduced the bioavailability of MeHg. Exposure of D. magna to MeHg at 2 ng/L in hard or soft water adjusted to pH 6.7 showed no significant difference in MeHg uptake, supporting an argument that hardness and alkalinity per se do not affect Me

  18. Molecular characterization, light-dependent expression, and cellular localization of a host vacuolar-type H+-ATPase (VHA) subunit A in the giant clam, Tridacna squamosa, indicate the involvement of the host VHA in the uptake of inorganic carbon and its supply to the symbiotic zooxanthellae.

    PubMed

    Ip, Yuen K; Hiong, Kum C; Lim, Leon J Y; Choo, Celine Y L; Boo, Mel V; Wong, Wai P; Neo, Mei L; Chew, Shit F

    2018-06-15

    The giant clam, Tridacna squamosa, represents a clam-zooxanthellae association. In light, the host clam and the symbiotic zooxanthellae conduct light-enhanced calcification and photosynthesis, respectively. We had cloned the cDNA coding sequence of a Vacuolar-type Proton ATPase (VHA) subunit A, ATP6V1A, from T. squamosa, whereby the VHA is an electrogenic transporter that actively 'pumps' H + out of the cell. The ATP6V1A of T. squamosa comprised 1866 bp, encoding a protein of 622 amino acids and 69.9 kDa, and had a host-origin. Its gene expression was strong in the ctenidium and the colorful outer mantle, but weak in the whitish inner mantle, corroborating a previous proposition that VHA might have a trivial role in light-enhanced calcification. Light exposure led to significant increases in the gene and protein expression levels of ATP6V1A/ATP6V1A in the ctenidium and the outer mantle. In the ctenidium, the ATP6V1A was localized in the apical epithelia of the filaments and tertiary water channels, indicating that the VHA could participate in the increased excretion of H + produced during light-enhanced calcification. Additionally, the excreted H + would augment HCO 3 - dehydration in the external medium and facilitate the uptake of CO 2 by the ctenidium during insolation. In the outer mantle, the ATP6V1A was detected in intracellular vesicles in a type of cells, presumably iridocytes, surrounding the zooxanthellal tubules, and in the apical epithelium of zooxanthellal tubules. Hence, the host VHA could participate in the transfer of inorganic carbon from the hemolymph to the luminal fluid of the tubules by increasing the supply of H + for the dehydration of HCO 3 - to CO 2 during insolation to benefit the photosynthesizing zooxanthellae. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Physiological response of a red tide alga (Skeletonema costatum) to nitrate enrichment, with special reference to inorganic carbon acquisition.

    PubMed

    Gao, Guang; Xia, Jianrong; Yu, Jinlan; Zeng, Xiaopeng

    2018-02-01

    A classical red tide alga Skeletonema costatum was cultured under various nitrate levels to investigate its physiological response to nitrate enrichment combined with CO 2 limitation. The higher nitrate levels increased content of photosynthetic pigments (Chl a and Chl c), electron transport rate in photosystem II, photosynthetic O 2 evolution, and thus growth rate in S. costatum. On the other hand, the lower CO 2 levels (3.5-4.4 μmol kg -1 seawater) and higher pH (8.56-8.63) values in seawater were observed under higher nitrate conditions. Redox activity of plasma membrane and carbonic anhydrase in S. costatum was enhanced to address the reduced CO 2 level at higher nitrate levels. In addition, the pH compensation point was enhanced and direct HCO 3 - use was induced at higher nitrate levels. These findings indicate that nitrate enrichment would stimulate the breakout of S. costatum dominated red tides via enhancing its photosynthetic performances, and maintain a quick growth rate under CO 2 limitation conditions through improving its inorganic carbon acquisition capability. Our study sheds light on the mechanisms of S. costatum defeating CO 2 limitation during algal bloom. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. [Multi-temporal scale analysis of impacts of extreme high temperature on net carbon uptake in subtropical coniferous plantation.

    PubMed

    Zhang, Mi; Wen, Xue Fa; Zhang, Lei Ming; Wang, Hui Min; Guo, Yi Wen; Yu, Gui Rui

    2018-02-01

    Extreme high temperature is one of important extreme weathers that impact forest ecosystem carbon cycle. In this study, applying CO 2 flux and routine meteorological data measured during 2003-2012, we examined the impacts of extreme high temperature and extreme high temperature event on net carbon uptake of subtropical coniferous plantation in Qianyanzhou. Combining with wavelet analysis, we analyzed environmental controls on net carbon uptake at different temporal scales, when the extreme high temperature and extreme high temperature event happened. The results showed that mean daily cumulative NEE decreased by 51% in the days with daily maximum air temperature range between 35 ℃ and 40 ℃, compared with that in the days with the range between 30 ℃ and 34 ℃. The effects of the extreme high temperature and extreme high temperature event on monthly NEE and annual NEE related to the strength and duration of extreme high tempe-rature event. In 2003, when strong extreme high temperature event happened, the sum of monthly cumulative NEE in July and August was only -11.64 g C·m -2 ·(2 month) -1 . The value decreased by 90%, compared with multi-year average value. At the same time, the relative variation of annual NEE reached -6.7%. In July and August, when the extreme high temperature and extreme high temperature event occurred, air temperature (T a ) and vapor press deficit (VPD) were the dominant controller for the daily variation of NEE. The coherency between NEE T a and NEE VPD was 0.97 and 0.95, respectively. At 8-, 16-, and 32-day periods, T a , VPD, soil water content at 5 cm depth (SWC), and precipitation (P) controlled NEE. The coherency between NEE SWC and NEE P was higher than 0.8 at monthly scale. The results indicated that atmospheric water deficit impacted NEE at short temporal scale, when the extreme high temperature and extreme high temperature event occurred, both of atmospheric water deficit and soil drought stress impacted NEE at long temporal