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Sample records for competing microbial respiration

  1. Effects of elevated CO2 concentrations on soil microbial respiration and root/rhizosphere respiration in-forest soils

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The two main components of soil respiration,i.e.,root/rhizosphere and microbial respiration,respond differently to elevated atmospheric CO2 concentrations both in mechanism and sensitivity because they have different substrates derived from plant and soil organic matter,respectively.To model the carbon cycle and predict the carbon source/sink of forest ecosystems,we must first understand the relative contributions of root/rhizosphere and microbial respiration to total soil respiration under elevated CO2 concentrations.Root/rhizosphere and soil microbial respiration have been shown to increase,decrease and remain unchanged under elevated CO2 concentrations.A significantly positive relationship between root biomass and root/rhizosphere respiration has been found.Fine roots respond more strongly to elevated CO2 concentrations than coarse roots.Evidence suggests that soil microbial respiration is highly variable and uncertain under elevated CO2 concentrations.Microbial biomass and activity are related or unrelated to rates of microbial respiration.Because substrate availability drives microbial metabolism in soils,it is likely that much of the variability in microbial respiration results from differences in the response of root growth to elevated CO2 concentrations and subsequent changes in substrate production.Biotic and abiotic factors affecting soil respiration were found to affect both root/rhizosphere and microbial respiration.

  2. Impact of some selected insecticides application on soil microbial respiration.

    Science.gov (United States)

    Latif, M A; Razzaque, M A; Rahman, M M

    2008-08-15

    The aim of present study was to investigate the impact of selected insecticides used for controlling brinjal shoot and fruit borer on soil microorganisms and to find out the insecticides or nontoxic to soil microorganism the impact of nine selected insecticides on soil microbial respiration was studied in the laboratory. After injection of different insecticides solutions, the soil was incubated in the laboratory at room temperature for 32 days. The amount of CO2 evolved due to soil microbial respiration was determined at 2, 4, 8, 16, 24 and 32 days of incubation. Flubendiamide, nimbicidine, lambda-cyhalothrin, abamectin and thiodicarb had stimulatory effect on microbial respiration during the initial period of incubation. Chlorpyriphos, cartap and carbosulfan had inhibitory effect on microbial respiration and cypermethrin had no remarkable effect during the early stage of incubation. The negative effect of chlorpyriphos, cartap and carbosulfan was temporary, which was disappeared after 4 days of insecticides application. No effect of the selected insecticides on soil microorganisms was observed after 24 or 32 days of incubation.

  3. Development of a Molecular System for Studying Microbial Arsenate Respiration

    Science.gov (United States)

    Saltikov, C. W.; Newman, D. K.

    2002-12-01

    The toxic element arsenic is a major contaminant of many groundwaters and surface waters throughout the world. Arsenic enrichment is primarily of geological origin resulting from weathering processes and geothermal activity. Not surprisingly, microorganisms inhabiting anoxic arsenic-contaminated environments have evolved to exploit arsenate during respiration. Numerous bacteria have been isolated that use arsenate as a terminal electron acceptor for respiratory growth. The diversity of this metabolism appears to be widespread throughout the microbial tree of life, suggesting respiratory arsenate reduction is ancient in origin. Yet little is known about the molecular mechanisms for how these organisms respire arsenate. We have developed a model system in Shewanella trabarsenatis, strain ANA-3, a facultative anaerobe that respires arsenate and tolerates high concentrations of arsenite (10 mM). Through loss-of-function studies, we have identified genes involved in both arsenic resistance and arsenate respiration. The genes that confer resistance to arsenic are homologous to the well-characterized ars operon of E. coli. However, the respiratory arsenate reductase is predicted to encode a novel protein that shares homologous regions (~ 40 % similarity) to molybdopterin anaerobic reductases specific for DMSO, thiosulfate, nitrate, and polysulfide. I will discuss our emerging model for how strain ANA-3 respires arsenate and the relationship between arsenite resistance and arsenate respiration. I will also highlight the relevance of this type of analysis for biogeochemical studies.

  4. Perspectives of the microbial carbon pump with special references to microbial respiration and ecological efficiency

    Science.gov (United States)

    Dang, H.; Jiao, N.

    2014-01-01

    Although respiration consumes fixed carbon and produce CO2, it provides energy for essential biological processes of an ecosystem, including the microbial carbon pump (MCP). In MCP-driving biotransformation of labile DOC to recalcitrant DOC (RDOC), microbial respiration provides the metabolic energy for environmental organic substrate sensing, cellular enzyme syntheses and catalytic processes such as uptake, secretion, modification, fixation and storage of carbon compounds. The MCP efficiency of a heterotrophic microorganism is thus related to its energy production efficiency and hence to its respiration efficiency. Anaerobically respiring microbes usually have lower energy production efficiency and lower energy-dependent carbon transformation efficiency, and consequently lower MCP efficiency at per cell level. This effect is masked by the phenomena that anoxic environments often store more organic matter. Here we point out that organic carbon preservation and RDOC production is different in mechanisms, and anaerobically respiring ecosystems could also have lower MCP ecological efficiency. Typical cases can be found in large river estuarine ecosystems. Due to strong terrigenous input of nutrients and organic matter, estuarine ecosystems usually experience intense heterotrophic respiration processes that rapidly consume dissolved oxygen, potentially producing hypoxic and anoxic zones in the water column. The lowered availability of dissolved oxygen and the excessive supply of nutrients such as nitrate from river input prompt enhanced anaerobic respiration processes. Thus, some nutrients may be consumed by anaerobically respiring heterotrophic microorganisms, instead of being utilized by phytoplankton for carbon fixation and primary production. In this situation, the ecological functioning of the estuarine ecosystem is altered and the ecological efficiency is lowered, as less carbon is fixed and less energy is produced. Ultimately this would have negatively impacts

  5. Perspectives of the microbial carbon pump with special references to microbial respiration and ecological efficiency

    Directory of Open Access Journals (Sweden)

    H. Dang

    2014-01-01

    Full Text Available Although respiration consumes fixed carbon and produce CO2, it provides energy for essential biological processes of an ecosystem, including the microbial carbon pump (MCP. In MCP-driving biotransformation of labile DOC to recalcitrant DOC (RDOC, microbial respiration provides the metabolic energy for environmental organic substrate sensing, cellular enzyme syntheses and catalytic processes such as uptake, secretion, modification, fixation and storage of carbon compounds. The MCP efficiency of a heterotrophic microorganism is thus related to its energy production efficiency and hence to its respiration efficiency. Anaerobically respiring microbes usually have lower energy production efficiency and lower energy-dependent carbon transformation efficiency, and consequently lower MCP efficiency at per cell level. This effect is masked by the phenomena that anoxic environments often store more organic matter. Here we point out that organic carbon preservation and RDOC production is different in mechanisms, and anaerobically respiring ecosystems could also have lower MCP ecological efficiency. Typical cases can be found in large river estuarine ecosystems. Due to strong terrigenous input of nutrients and organic matter, estuarine ecosystems usually experience intense heterotrophic respiration processes that rapidly consume dissolved oxygen, potentially producing hypoxic and anoxic zones in the water column. The lowered availability of dissolved oxygen and the excessive supply of nutrients such as nitrate from river input prompt enhanced anaerobic respiration processes. Thus, some nutrients may be consumed by anaerobically respiring heterotrophic microorganisms, instead of being utilized by phytoplankton for carbon fixation and primary production. In this situation, the ecological functioning of the estuarine ecosystem is altered and the ecological efficiency is lowered, as less carbon is fixed and less energy is produced. Ultimately this would have

  6. Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones

    DEFF Research Database (Denmark)

    Kalvelage, Tim; Lavik, Gaute; Jensen, Marlene Mark

    2015-01-01

    denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off...... and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results......Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic...

  7. Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones.

    Science.gov (United States)

    Kalvelage, Tim; Lavik, Gaute; Jensen, Marlene M; Revsbech, Niels Peter; Löscher, Carolin; Schunck, Harald; Desai, Dhwani K; Hauss, Helena; Kiko, Rainer; Holtappels, Moritz; LaRoche, Julie; Schmitz, Ruth A; Graco, Michelle I; Kuypers, Marcel M M

    2015-01-01

    Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein.

  8. Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones.

    Directory of Open Access Journals (Sweden)

    Tim Kalvelage

    Full Text Available Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100% in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein.

  9. Soil organic matter content: a non-liner control on microbial respiration in soils

    Science.gov (United States)

    Schnecker, Jörg; Grandy, Stuart

    2016-04-01

    It is widely assumed that microbial activity and respiration rates respond linearly to substrate concentrations, irrespective of substrate chemical characteristics, but this assumption remains largely untested. We know that microbial decomposition of soil organic matter (SOM) and the amount of CO2 respired from soil depends on substrate availability. While soils with high SOM concentrations will have higher respiration rates than soils with low SOM concentrations, the specific relationship between substrate quantity and CO2 respired and its underlying mechanisms has robust theoretical, modeling, and management implications. In a lab incubation experiment, we amended a mixture of agricultural soil and sand with increasing amounts of one of three plant residues differing in their C/N ratio (clover C/N 14; rye C/N 23 and wheat straw C/N 110). Keeping the soil/sand mixture at a constant ratio, we obtained 9 levels of organic carbon (OC) content ranging from 0.25% to 5.7%. The sand-soil-residue mixtures were then incubated at constant temperature and water contents for a total of 63 days. Our results show that across substrates CO2 production increased with increasing OC content following a sigmoidal curve function instead of the expected linear one. A breakpoint analysis for the respiration curve of rye revealed two significant break points at 1.3 and 3.8 % OC. The three individual linear relations might be shaped by spatial separation of substrate and microbes and the interaction of the microbes themselves. In the first "survival" phase up to 1.3 % OC, more substrate leads to the survival of more microbes. However, microbial growth does not result in the discovery of new resources. In the "expansion" phase (1.3 % OC to 3.8 % OC), microbial growth is successful and microbes can exploit new resources. Finally, in the "competition" phase microbes start to compete for space and resources, which leads to a decrease in decomposition and respiration. While the results for

  10. Effects of assimilate supply on root and microbial components of soil respiration in a mountain grassland.

    Science.gov (United States)

    Schmitt, M.; Siegwolf, R.; Ekblad, A.; Pfahringer, N.; Bahn, M.

    2012-04-01

    Soil respiration is the main source of carbon emitted from terrestrial ecosystems. Soil CO2 originates from multiple processes, comprising respiration by plant roots, mycorrhizae and microbes in the rhizosphere, as well as respiration due to soil organic matter (SOM) decomposition. Thus, components of soil respiration have different controls and show varying responses to changing environmental conditions and to the supply of fresh assimilates from photosynthesis. For grasslands there is still little information available as to what extent root and microbial respiration respond to reduced or enhanced assimilate supply. The aim of this study was to assess effects of assimilate supply on root and microbial components of soil respiration in a temperate mountain grassland. Root and microbial components were separated and quantified by applying the Substrate Induced Respiration method (SIR) in situ using a δ13C labelled sucrose solution, and analysing δ13C of the subsequently respired CO2. Assimilate supply was modified by clipping and shading treatments, which strongly reduced photosynthetic C supply, and by applying a sucrose solution 8 days after clipping and shading. We tested the hypotheses that (1) due to a reduction of assimilate supply, soil respiration would be lower in the clipped and shaded than in the control treatment, that (2) the microbial contribution to soil respiration would be lower in the assimilate-limited than in the control treatments, and that (3) priming effects following the addition of sucrose would be stronger in shaded and mowed treatments than in control plots. Our results showed that clipping and shading reduced soil respiration significantly. Whilst the microbial contribution to soil respiration was 61% in control plots, it amounted to only 50-48% in clipped and shaded plots, respectively. Sucrose application did not affect root respiration in any of the plots, but generally stimulated microbial respiration. The measured priming effect

  11. [Effects of different straw recycling and tillage methods on soil respiration and microbial activity].

    Science.gov (United States)

    Li, Xiao-sha; Wu, Ning; Liu, Ling; Feng, Yu-peng; Xu, Xu; Han, Hui-fang; Ning, Tang-yuan; Li, Zeng-jia

    2015-06-01

    To explore the effects of different tillage methods and straw recycling on soil respiration and microbial activity in summer maize field during the winter wheat and summer maize double cropping system, substrate induced respiration method and CO2 release method were used to determine soil microbial biomass carbon, microbial activity, soil respiration, and microbial respiratory quotient. The experiment included 3 tillage methods during the winter wheat growing season, i.e., no-tillage, subsoiling and conventional tillage. Each tillage method was companied with 2 straw management patterns, i.e., straw recycling and no straw. The results indicated that the conservation tillage methods and straw recycling mainly affected 0-10 cm soil layer. Straw recycling could significantly improve the microbial biomass carbon and microbial activity, while decrease microbial respiratory quotient. Straw recycling could improve the soil respiration at both seedling stage and anthesis, however, it could reduce the soil respiration at filling stage, wax ripeness, and harvest stage. Under the same straw application, compared with conventional tillage, the soil respiration and microbial respiratory quotient in both subsoiling and no-tillage were reduced, while the microbial biomass carbon and microbial activity were increased. During the summer maize growing season, soil microbial biomass carbon and microbial activity were increased in straw returning with conservation tillage, while the respiratory quotient was reduced. In 0-10 cm soil layer, compared with conventional tillage, straw recycling with subsoiling and no-tillage significantly increased soil microbial biomass carbon by 95.8% and 74.3%, and increased soil microbial activity by 97.1% and 74.2%, respectively.

  12. Spartina alterniflora invasion alters soil microbial community composition and microbial respiration following invasion chronosequence in a coastal wetland of China

    Science.gov (United States)

    Yang, Wen; Jeelani, Nasreen; Leng, Xin; Cheng, Xiaoli; An, Shuqing

    2016-05-01

    The role of exotic plants in regulating soil microbial community structure and activity following invasion chronosequence remains unclear. We investigated soil microbial community structure and microbial respiration following Spartina alterniflora invasion in a chronosequence of 6-, 10-, 17-, and 20-year-old by comparing with bare flat in a coastal wetland of China. S. alterniflora invasion significantly increased soil moisture and salinity, the concentrations of soil water-soluble organic carbon and microbial biomass carbon (MBC), the quantities of total and various types of phospholipid fatty acids (PLFAs), the fungal:bacterial PLFAs ratio and cumulative microbial respiration compared with bare flat. The highest MBC, gram-negative bacterial and saturated straight-chain PLFAs were found in 10-year-old S. alterniflora soil, while the greatest total PLFAs, bacterial and gram-positive bacterial PLFAs were found in 10- and 17-year-old S. alterniflora soils. The monounsaturated:branched PLFAs ratio declined, and cumulative microbial respiration on a per-unit-PLFAs increased following S. alterniflora invasion in the chronosequence. Our results suggest that S. alterniflora invasion significantly increased the biomass of soil various microbial groups and microbial respiration compared to bare flat soil by increasing soil available substrate, and modifying soil physiochemical properties. Soil microbial community reached the most enriched condition in the 10-year-old S. alterniflora community.

  13. Temperature sensitivity of soil microbial communities: An application of macromolecular rate theory to microbial respiration

    Science.gov (United States)

    Alster, Charlotte J.; Koyama, Akihiro; Johnson, Nels G.; Wallenstein, Matthew D.; Fischer, Joseph C.

    2016-06-01

    There is compelling evidence that microbial communities vary widely in their temperature sensitivity and may adapt to warming through time. To date, this sensitivity has been largely characterized using a range of models relying on versions of the Arrhenius equation, which predicts an exponential increase in reaction rate with temperature. However, there is growing evidence from laboratory and field studies that observe nonmonotonic responses of reaction rates to variation in temperature, indicating that Arrhenius is not an appropriate model for quantitatively characterizing temperature sensitivity. Recently, Hobbs et al. (2013) developed macromolecular rate theory (MMRT), which incorporates thermodynamic temperature optima as arising from heat capacity differences between isoenzymes. We applied MMRT to measurements of respiration from soils incubated at different temperatures. These soils were collected from three grassland sites across the U.S. Great Plains and reciprocally transplanted, allowing us to isolate the effects of microbial community type from edaphic factors. We found that microbial community type explained roughly 30% of the variation in the CO2 production rate from the labile C pool but that temperature and soil type were most important in explaining variation in labile and recalcitrant C pool size. For six out of the nine soil × inoculum combinations, MMRT was superior to Arrhenius. The MMRT analysis revealed that microbial communities have distinct heat capacity values and temperature sensitivities sometimes independent of soil type. These results challenge the current paradigm for modeling temperature sensitivity of soil C pools and understanding of microbial enzyme dynamics.

  14. Energetic Limitations on Microbial Respiration of Organic Compounds using Aqueous Fe(III) Complexes

    Science.gov (United States)

    Naughton, H.; Fendorf, S. E.

    2015-12-01

    Soil organic matter constitutes up to 75% of the terrestrial carbon stock. Microorganisms mediate the breakdown of organic compounds and the return of carbon to the atmosphere, predominantly through respiration. Microbial respiration requires an electron acceptor and an electron donor such as small fatty acids, organic acids, alcohols, sugars, and other molecules that differ in oxidation state of carbon. Carbon redox state affects how much energy is required to oxidize a molecule through respiration. Therefore, different organic compounds should offer a spectrum of energies to respiring microorganisms. However, microbial respiration has traditionally focused on the availability and reduction potential of electron acceptors, ignoring the organic electron donor. We found through incubation experiments that the organic compound serving as electron donor determined how rapidly Shewanella putrefaciens CN32 respires organic substrate and the extent of reduction of the electron acceptor. We simulated a range of energetically favorable to unfavorable electron acceptors using organic chelators bound to Fe(III) with equilibrium stability constants ranging from log(K) of 11.5 to 25.0 for the 1:1 complex, where more stable complexes are less favorable for microbial respiration. Organic substrates varied in nominal oxidation state of carbon from +2 to -2. The most energetically favorable substrate, lactate, promoted up to 30x more rapid increase in percent Fe(II) compared to less favorable substrates such as formate. This increased respiration on lactate was more substantial with less stable Fe(III)-chelate complexes. Intriguingly, this pattern contradicts respiration rate predicted by nominal oxidation state of carbon. Our results suggest that organic substrates will be consumed so long as the energetic toll corresponding to the electron donor half reaction is counterbalanced by the energy available from the electron accepting half reaction. We propose using the chemical

  15. [Soil Microbial Respiration Under Different Soil Temperature Conditions and Its Relationship to Soil Dissolved Organic Carbon and Invertase].

    Science.gov (United States)

    Wu, Jing; Chen, Shu-tao; Hu, Zheng-hua; Zhang, Xu

    2015-04-01

    In order to investigate the soil microbial respiration under different temperature conditions and its relationship to soil dissolved organic carbon ( DOC) and invertase, an indoor incubation experiment was performed. The soil samples used for the experiment were taken from Laoshan, Zijinshan, and Baohuashan. The responses of soil microbial respiration to the increasing temperature were studied. The soil DOC content and invertase activity were also measured at the end of incubation. Results showed that relationships between cumulative microbial respiration of different soils and soil temperature could be explained by exponential functions, which had P values lower than 0.001. The coefficient of temperature sensitivity (Q10 value) varied from 1.762 to 1.895. The Q10 value of cumulative microbial respiration decreased with the increase of soil temperature for all soils. The Q10 value of microbial respiration on 27 days after incubation was close to that of 1 day after incubation, indicating that the temperature sensitivity of recalcitrant organic carbon may be similar to that of labile organic carbon. For all soils, a highly significant ( P = 0.003 ) linear relationship between cumulative soil microbial respiration and soil DOC content could be observed. Soil DOC content could explain 31.6% variances of cumulative soil microbial respiration. For the individual soil and all soils, the relationship between cumulative soil microbial respiration and invertase activity could be explained by a highly significant (P soil microbial respiration.

  16. Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones

    DEFF Research Database (Denmark)

    Kalvelage, Tim; Lavik, Gaute; Jensen, Marlene Mark;

    2015-01-01

    denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off...... suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein....

  17. Carbon dioxide emission and soil microbial respiration activity of Chernozems under anthropogenic transformation of terrestrial ecosystems

    Directory of Open Access Journals (Sweden)

    Nadezhda D. Ananyeva

    2016-04-01

    Full Text Available The total soil CO2 emission (EM and portion of microbial respiration were measured (in situ; May, June, July 2015 in Chernozems typical of virgin steppe, oak forest, bare fallow and urban ecosystems (Kursk region, Russia. In soil samples (upper 10 cm layer, the soil microbial biomass carbon (Cmic, basal respiration (BR and fungi-to-bacteria ratio were determined and the specific microbial respiration (BR / Cmic = qCO2 was calculated. The EM was varied from 2.0 (fallow to 23.2 (steppe g СО2 m-2 d-1. The portion of microbial respiration in EM was reached in average 83, 51 and 60% for forest, steppe and urban, respectively. The soil Cmic and BR were decreased along a gradient of ecosystems transformation (by 4 and 2 times less, respectively, while the qCO2 of urban soil was higher (in average by 42% compared to steppe, forest and fallow. In urban soil the Cmic portion in soil Сorg and Сfungi-to-Сorg ratio were by 2.6 and 2.4 times less than those for steppe. The relationship between microbial respiration and BR values in Chernozems of various ecosystems was significant (R2 = 0.57.

  18. Responses of soil microbial respiration to plantations depend on soil properties in subtropical China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yan-jie; YAN Yue; FU Xiang-ping; YANG Jie; ZHANG Su-yan; XU Shan; TANG Zheng; LI Zhong-fang; LU Shun-bao

    2016-01-01

    Assessing the impact of plantation on microbial respiration (MR) is vitaly important to understand the interactions between belowground metabolism and land use change. In this study, cumulative MR was determined by alkali absorption method in 1, 3, 7, 14, 21, 28, 35, 42, 49, and 56 days from the soil in a representative plantations in the subtropical region of China. The treatment of plantations contained no plant (CK), orange trees (Citrus reticulata)+Bahia grass (Paspalum notatum) (GB), orange trees (C. reticulata)+Bahia grass (P.notatum)+soybean (Giycine max(L.)Merril) (GBH). Results showed that plantation had signiifcant effects on microbial respiration and the responses of microbial respiration to plantation from different soil layers and topographies were different: in 0–20 cm in uphil: GB>GBH>CK; in 20–40 cm in uphil: GBH>CK>GB; in 0–20 cm in downhil: GBH>CK>GB; in 20–40 cm in downhil: GB>CK>GBH. Furthermore, plantation also altered the relationships between MR and soil properties. In CK, microbial respiration was positively correlated with NH4+ and soil total N, and negatively correlated with soil moisture, pH, NO3–, and microbial biomass carbon (MBC). In GB, microbial respira-tion under GB signiifcantly negatively correlated with dissolved organic carbon (DOC). In GBH, microbial respiration under GBH was positively correlated with NH4+, MBC, total soil carbon (TC), and total soil nitrogen (TN), and negatively correlated with soil moisture (SM), pH, NO3–, and DOC. The underlying mechanisms could be attributed to soil heterogeneity and the effects of plantation on soil properties. Our results also showed that plantation signiifcantly increased soil C storage, which suggested plantation is a key measure to enhance soil C sequestration and mitigate global CO2 emission, especialy for the soil with low initial soil carbon content or bared soil.

  19. Contribution of Chloroflexus respiration to oxygen cycling in a hypersaline microbial mat from Lake Chiprana, Spain

    DEFF Research Database (Denmark)

    Polerecky, Lubos; Bachar, Ami; Schoon, Raphaela

    2007-01-01

    in the visible (VIS) and near infrared (NIR) regions to study this coupling in more detail. Using this novel approach, we separately quantified the activity of the major players in the oxygen cycle in a hypersaline microbial mat: gross photosynthesis of cyanobacteria, NIR light-dependent respiration......In dense stratified systems such as microbial mats, photosynthesis and respiration are coupled due to a tight spatial overlap between oxygen-producing and -consuming microorganisms. We combined microsensors and a membrane inlet mass spectrometer with two independent light sources emitting...... of Chloroflexus-like bacteria (CLB) and respiration of aerobic heterotrophs. Illumination by VIS light induced oxygen production in the top 1 mm of the mat. In this zone CLB were found responsible for all respiration, while the contribution of the aerobic heterotrophs was negligible. Additional illumination...

  20. Comparing how land use change impacts soil microbial catabolic respiration in Southwestern Amazon

    Directory of Open Access Journals (Sweden)

    Andre Mancebo Mazzetto

    2016-03-01

    Full Text Available Abstract Land use changes strongly impact soil functions, particularly microbial biomass diversity and activity. We hypothesized that the catabolic respiration response of the microbial biomass would differ depending on land use and that these differences would be consistent at the landscape scale. In the present study, we analyzed the catabolic response profile of the soil microbial biomass through substrate-induced respiration in different land uses over a wide geographical range in Mato Grosso and Rondônia state (Southwest Amazon region. We analyzed the differences among native areas, pastures and crop areas and within each land use and examined only native areas (Forest, Dense Cerrado and Cerrado, pastures (Nominal, Degraded and Improved and crop areas (Perennial, No-Tillage, Conventional Tillage. The metabolic profile of the microbial biomass was accessed using substrate-induced respiration. Pasture soils showed significant responses to amino acids and carboxylic acids, whereas native areas showed higher responses to malonic acid, malic acid and succinic acid. Within each land use category, the catabolic responses showed similar patterns in both large general comparisons (native area, pasture and crop areas and more specific comparisons (biomes, pastures and crop types. The results showed that the catabolic responses of the microbial biomass are highly correlated with land use, independent of soil type or climate. The substrate induced respiration approach is useful to discriminate microbial communities, even on a large scale.

  1. Comparing how land use change impacts soil microbial catabolic respiration in Southwestern Amazon.

    Science.gov (United States)

    Mazzetto, Andre Mancebo; Feigl, Brigitte Josefine; Cerri, Carlos Eduardo Pellegrino; Cerri, Carlos Clemente

    2016-01-01

    Land use changes strongly impact soil functions, particularly microbial biomass diversity and activity. We hypothesized that the catabolic respiration response of the microbial biomass would differ depending on land use and that these differences would be consistent at the landscape scale. In the present study, we analyzed the catabolic response profile of the soil microbial biomass through substrate-induced respiration in different land uses over a wide geographical range in Mato Grosso and Rondônia state (Southwest Amazon region). We analyzed the differences among native areas, pastures and crop areas and within each land use and examined only native areas (Forest, Dense Cerrado and Cerrado), pastures (Nominal, Degraded and Improved) and crop areas (Perennial, No-Tillage, Conventional Tillage). The metabolic profile of the microbial biomass was accessed using substrate-induced respiration. Pasture soils showed significant responses to amino acids and carboxylic acids, whereas native areas showed higher responses to malonic acid, malic acid and succinic acid. Within each land use category, the catabolic responses showed similar patterns in both large general comparisons (native area, pasture and crop areas) and more specific comparisons (biomes, pastures and crop types). The results showed that the catabolic responses of the microbial biomass are highly correlated with land use, independent of soil type or climate. The substrate induced respiration approach is useful to discriminate microbial communities, even on a large scale.

  2. Microbial properties explain temporal variation in soil respiration in a grassland subjected to nitrogen addition

    Science.gov (United States)

    Li, Yue; Liu, Yinghui; Wu, Shanmei; Niu, Lei; Tian, Yuqiang

    2015-12-01

    The role of soil microbial variables in shaping the temporal variability of soil respiration has been well acknowledged but is poorly understood, particularly under elevated nitrogen (N) deposition conditions. We measured soil respiration along with soil microbial properties during the early, middle, and late growing seasons in temperate grassland plots that had been treated with N additions of 0, 2, 4, 8, 16, or 32 g N m-2 yr-1 for 10 years. Representing the averages over three observation periods, total (Rs) and heterotrophic (Rh) respiration were highest with 4 g N m-2 yr-1, but autotrophic respiration (Ra) was highest with 8 to 16 g N m-2 yr-1. Also, the responses of Rh and Ra were unsynchronized considering the periods separately. N addition had no significant impact on the temperature sensitivity (Q10) for Rs but inhibited the Q10 for Rh. Significant interactions between observation period and N level occurred in soil respiration components, and the temporal variations in soil respiration components were mostly associated with changes in microbial biomass carbon (MBC) and phospholipid fatty acids (PLFAs). Further observation on soil organic carbon and root biomass is needed to reveal the long-term effect of N deposition on soil C sequestration.

  3. Responses of microbial respiration in grazed and ungrazed grasslands to glucose addition

    Science.gov (United States)

    Xu, Xingliang; Liu, Qianyuan; Pang, Rui

    2017-04-01

    Grazing can change species composition, alter soil properties, and thus modify microbial activities, affecting biogeochemical processes in grasslands. However, it remains unclear how microbial respiration in grazed and ungrazed grasslands responds to glucose addition. Here we hypothesize that microbial respiration in grazed grasslands will respond more strongly to glucose addition than in ungrazed grasslands because moderate grazing can enhance microbial activity. To examine the hypothesis above, we collected the upper 10 cm soil from grazed and ungrazed grasslands at five sites of China. Three sites (Hulunbuir 1, Hulunbuir 2 and Xielingele) were located in Inner Mongolia and two in the Tibet Plateau) Soils were incubated with low glucose input (50% MBC), high glucose input (150% MBC), and water for 60 days in 21oC. CO2 released from soil was trapped with 1 M NaOH. The results showed that the effect of grazing on microbial respiration has two distinct patterns, depending on soil types and addition amount. After glucose addition, cumulative CO2 efflux from grazed soils was significantly higher than from ungrazed soils in two temperate grasslands (Hulunbuir 1 and Xielingele). This may be ascribed to that moderate grazing promoted microbial activity. On the contrary, microbial respirations from grazed soils were lower than ungrazed soils in two alpine meadows of Haibei and Dangxiong and in Hulunbuir 2. This effect of grazing was not obvious in Hulunbeier 2 soils at low carbon addition level. Grazing may decrease soil organic carbon, nitrogen availability and thus microbial activity in alpine grasslands. These findings indicate that soil microorganisms could have different adaptation mechanisms to grazing in temperate and alpine grasslands.

  4. Microbial respiration and extracellular enzyme activity in sediments from the Gulf of Mexico hypoxic zone

    Science.gov (United States)

    This study explores the relationship between sediment chemistry (TC, TN, TP) and microbial respiration (DHA) and extracellular enzyme activity (EEA) across the Gulf of Mexico (GOM) hypoxic zone. TC, TN, and TP were all positively correlated with each other (r=0.19-0.68). DHA was ...

  5. Microbial respiration and extracellular enzyme activity in sediments from the Gulf of Mexico hypoxic zone

    Science.gov (United States)

    This study explores the relationship between sediment chemistry (TC, TN, TP) and microbial respiration (DHA) and extracellular enzyme activity (EEA) across the Gulf of Mexico (GOM) hypoxic zone. TC, TN, and TP were all positively correlated with each other (r=0.19-0.68). DHA was ...

  6. Soil microbial respiration and PICT responses to an industrial and historic lead pollution: a field study.

    Science.gov (United States)

    Bérard, Annette; Capowiez, Line; Mombo, Stéphane; Schreck, Eva; Dumat, Camille; Deola, Frédéric; Capowiez, Yvan

    2016-03-01

    We performed a field investigation to study the long-term impacts of Pb soil contamination on soil microbial communities and their catabolic structure in the context of an industrial site consisting of a plot of land surrounding a secondary lead smelter. Microbial biomass, catabolic profiles, and ecotoxicological responses (PICT) were monitored on soils sampled at selected locations along 110-m transects established on the site. We confirmed the high toxicity of Pb on respirations and microbial and fungal biomasses by measuring positive correlations with distance from the wall factory and negative correlation with total Pb concentrations. Pb contamination also induced changes in microbial and fungal catabolic structure (from carbohydrates to amino acids through carboxylic malic acid). Moreover, PICT measurement allowed to establish causal linkages between lead and its effect on biological communities taking into account the contamination history of the ecosystem at community level. The positive correlation between qCO2 (based on respiration and substrate use) and PICT suggested that the Pb stress-induced acquisition of tolerance came at a greater energy cost for microbial communities in order to cope with the toxicity of the metal. In this industrial context of long-term polymetallic contamination dominated by Pb in a field experiment, we confirmed impacts of this metal on soil functioning through microbial communities, as previously observed for earthworm communities.

  7. Microbial Mechanisms Underlying Acidity-induced Reduction in Soil Respiration Under Nitrogen Fertilization

    Science.gov (United States)

    Niu, S.; Li, Y.

    2016-12-01

    Terrestrial ecosystems are receiving increasing amounts of reactive nitrogen (N) due to anthropogenic activities, which largely changes soil respiration and its feedback to climate change. N enrichment can not only increase N availability but also induce soil acidification, both may affect soil microbial activity and root growth with a consequent impact on soil respiration. However, it remains unclear whether elevated N availability or soil acidity has greater impact on soil respiration (Rs). We conducted a manipulative experiment to simulate N enrichment (10 g m-2 yr-1 NH4NO3) and soil acidity (0.552 mol H+ m-2 yr-1 sulfuric acid) and studied their effects on Rs and its components in a temperate forest. Our results showed that soil pH was reduced by 0.2 under N addition or acid addition treatment. Acid addition significantly decreased autotrophic respiration (Ra) and heterotrophic respiration (Rh) by 21.5% and 22.7% in 2014, 34.8% and 21.9% in 2015, respectively, resulting in a reduction of Rs by 22.2% in 2014 and 26.1% in 2015. Nitrogen enrichment reduced Ra, Rh, Rs by 21.9%, 16.2%, 18.6% in 2014 and 22.1%, 5.9%, 11.7% in 2015, respectively. The reductions of Rs and its components were attributable to decrease of fine root biomass, microbial biomass, and cellulose degrading enzymes. N addition did not change microbial community but acid addition increased both fungal and arbuscular mycorrhiza fungi PLFAs, and N plus acid addition significantly enhanced fungal to bacterial ratio. All the hydrolase enzymes were reduced more by soil acidity (43-50%) than nitrogen addition (30-39%). Structural equation model showed that soil acidity played more important role than N availability in reducing soil respiration mainly by changing microbial extracellular enzymes. We therefore suggest that N deposition induced indirect effect of soil acidification on microbial properties is critical and should be taken into account to better understand and predict ecosystem C cycling in

  8. Aerobic microbial respiration in 86-million-year-old deep-sea red clay.

    Science.gov (United States)

    Røy, Hans; Kallmeyer, Jens; Adhikari, Rishi Ram; Pockalny, Robert; Jørgensen, Bo Barker; D'Hondt, Steven

    2012-05-18

    Microbial communities can subsist at depth in marine sediments without fresh supply of organic matter for millions of years. At threshold sedimentation rates of 1 millimeter per 1000 years, the low rates of microbial community metabolism in the North Pacific Gyre allow sediments to remain oxygenated tens of meters below the sea floor. We found that the oxygen respiration rates dropped from 10 micromoles of O(2) liter(-1) year(-1) near the sediment-water interface to 0.001 micromoles of O(2) liter(-1) year(-1) at 30-meter depth within 86 million-year-old sediment. The cell-specific respiration rate decreased with depth but stabilized at around 10(-3) femtomoles of O(2) cell(-1) day(-1) 10 meters below the seafloor. This result indicated that the community size is controlled by the rate of carbon oxidation and thereby by the low available energy flux.

  9. Parameters of microbial respiration in soils of the impact zone of a mineral fertilizer factory

    Science.gov (United States)

    Zhukova, A. D.; Khomyakov, D. M.

    2015-08-01

    The carbon content in the microbial biomass and the microbial production of CO2 (the biological component of soil respiration) were determined in the upper layer (0-10 cm) of soils in the impact zone of the OJSC Voskresensk Mineral Fertilizers, one of the largest factories manufacturing mineral fertilizers in Russia. Statistical characteristics and schematic distribution of the biological parameters in the soil cover of the impact zone were analyzed. The degree of disturbance of microbial communities in the studied objects varied from weak to medium. The maximum value (0.44) was observed on the sampling plot 4 km away from the factory and 0.5 km away from the place of waste (phosphogypsum) storage. Significantly lower carbon content in the microbial biomass and its specific respiration were recorded in the agrosoddy-podzolic soil as compared with the alluvial soil sampled at the same distance from the plant. The effects of potential soil pollutants (fluorine, sulfur, cadmium, and stable strontium) on the characteristics of soil microbial communities were described with reliable regression equations.

  10. Microbial respiration and gene expression as a function of very low oxygen concentration

    DEFF Research Database (Denmark)

    Tiano, Laura

    Oxygen (O2) is a fundamental parameter for life. It not only profoundly influences the biogeochemical cycling on a global scale, but also deals with the regulation of metabolic processes at microbial level, in particular the transition between aerobic and anaerobic metabolisms. However, until...... recently, due to the lack of high-resolution methods for O2 concentration determination, several oxygen-related processes, such as aerobic respiration in pelagic aquatic ecosystems and in naturally oxygen poor waters (e.g. Oxygen Minimum Zones, OMZs), or the oxygen regulation of nitrification...... and denitrification, were only partially described. In spite of the importance of aerobic respiration as a key process in the global carbon cycle, the available data are still few, and highly biased with respect to season, latitude and depth. The main aims of this Ph.D were to: i) develop and test a highly...

  11. Microbial fuel cells as discontinuous portable power sources: syntropic interactions with anode-respiring bacteria.

    Science.gov (United States)

    Gao, Yaohuan; An, Junyeong; Ryu, Hodon; Lee, Hyung-Sool

    2014-04-01

    For microbial fuel cells (MFCs) to work as portable power sources used in a discontinuous manner, anode-respiring bacteria (ARB) should survive for at least several days in the absence of exogenous electron donors, and immediately generate current upon addition of an electron donor. Here, we proved that biopolymer-accumulating bacteria provide substrate (fuel) for ARB to generate current in lack of exogenous electron donor in 4 days, which allows MFCs to be used as portable power sources. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Differential response of microbial respiration to supplied nitrogen forms in 3 contrasting alpine meadow soils on the Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Xiaoyang Zeng

    Full Text Available ABSTRACT An incubation experiment was conducted to examine the effects of nitrogen (N applications in different forms (NH4NO3, NH4Cl, and KNO3 on microbial respiration considering 3 different alpine meadow soils (C poor soil, pH = 8.1, 1.6% C; C moderate soil, pH = 6.0, 5.0% C; C rich soil, pH = 7.1, 7.4% C in the Tibetan Plateau. The addition of NH4NO3 and NH4Cl increased the microbial respiration in C poor soil, but KNO3 had no effect. The inorganic N forms had no effects on C rich soil, but decreased microbial respiration in C moderate soil. Soil microbial respiration levels across the different types were ordered as follows: C poor soil < C rich soil < C moderate soil, regardless of N addition. These results suggest that the effect of N on microbial respiration in alpine meadow soils is more dependent on the initial soil pH than on soil C availability.

  13. Salinity influence on soil microbial respiration rate of wetland in the Yangtze River estuary through changing microbial community

    Institute of Scientific and Technical Information of China (English)

    Xue Fei Xi; Lei Wang; Jia Jun Hu; Yu Shu Tang; Yu Hu; Xiao Hua Fu; Ying Sun

    2014-01-01

    Estuarine wetland,where freshwater mixes with salt water,comprises different regions (rivers and marine ecosystems) with significantly varying tidal salinities.Two sampling areas,ZXS and JS,were selected to investigate the effect of tidal salinity on soil respiration (SR).ZXS and JS were located in Zhongxia Shoal and Jiangyanan Shoal of Jiuduansha Wetland respectively,with similar elevation and plant species,but significantly different in salinity.The results showed that with almost identical plant biomass,the SR and soil microbial respiration (SMR) of the tidal wetland with lower salinity (JS) were significantly higher than those of the tidal wetland with higher salinity (ZXS) (p < 0.05).However,unlike SMR and SR,the difference in the soil microbial biomass (SMB) was not significant (p > 0.05) with the SMB of ZXS a little higher than that of JS.The higher SMR and SR of JS may be closely connected to the soil microbial community structures and amount of dominant bacteria.Abundant β-and γ-Proteobacteria and Actinobacteria in JS soil,which have strong heterotrophic metabolic capabilities,could be the main reason for higher SMR and SR,whereas a high number of ε-Proteobacteria in ZXS,some of which have carbon fixation ability,could be responsible for relatively lower carbon output.Path analysis indicated that soil salinity had the maximum negative total influencing coefficient with SMR among the various soil physical and chemical factors,suggesting that higher soil salinity,restricting highly heterotrophic bacteria,is the principle reason for lower SMR and SR in the ZXS.

  14. Modelling highly variable environmental factors to assess potential microbial respiration in complex floodplain landscapes

    Science.gov (United States)

    Tritthart, Michael; Welti, Nina; Bondar-Kunze, Elisabeth; Pinay, Gilles; Hein, Thomas; Habersack, Helmut

    2011-01-01

    The hydrological exchange conditions strongly determine the biogeochemical dynamics in river systems. More specifically, the connectivity of surface waters between main channels and floodplains is directly controlling the delivery of organic matter and nutrients into the floodplains, where biogeochemical processes recycle them with high rates of activity. Hence, an in-depth understanding of the connectivity patterns between main channel and floodplains is important for the modelling of potential gas emissions in floodplain landscapes. A modelling framework that combines steady-state hydrodynamic simulations with long-term discharge hydrographs was developed to calculate water depths as well as statistical probabilities and event durations for every node of a computation mesh being connected to the main river. The modelling framework was applied to two study sites in the floodplains of the Austrian Danube River, East of Vienna. Validation of modelled flood events showed good agreement with gauge readings. Together with measured sediment properties, results of the validated connectivity model were used as basis for a predictive model yielding patterns of potential microbial respiration based on the best fit between characteristics of a number of sampling sites and the corresponding modelled parameters. Hot spots of potential microbial respiration were found in areas of lower connectivity if connected during higher discharges and areas of high water depths. PMID:27667961

  15. Effects of myclobutanil on soil microbial biomass, respiration, and soil nitrogen transformations.

    Science.gov (United States)

    Ju, Chao; Xu, Jun; Wu, Xiaohu; Dong, Fengshou; Liu, Xingang; Zheng, Yongquan

    2016-01-01

    A 3-month-long experiment was conducted to ascertain the effects of different concentrations of myclobutanil (0.4 mg kg(-1) soil [T1]; 1.2 mg kg(-1) soil [T3]; and 4 mg kg(-1) soil [T10]) on soil microbial biomass, respiration, and soil nitrogen transformations using two typical agricultural soils (Henan fluvo-aquic soil and Shanxi cinnamon soil). Soil was sampled after 7, 15, 30, 60, and 90 days of incubation to determine myclobutanil concentration and microbial parameters: soil basal respiration (RB), microbial biomass carbon (MBC) and nitrogen (MBN), NO(-)3-N and NH(+)4-N concentrations, and gene abundance of total bacteria, N2-fixing bacteria, fungi, ammonia-oxidizing archaea (AOA), and ammonia-oxidizing bacteria (AOB). The half-lives of the different doses of myclobutanil varied from 20.3 to 69.3 d in the Henan soil and from 99 to 138.6 d in the Shanxi soil. In the Henan soil, the three treatments caused different degrees of short-term inhibition of RB and MBC, NH(+)4-N, and gene abundance of total bacteria, fungi, N2-fixing bacteria, AOA, and AOB, with the exception of a brief increase in NO(-)3-N content during the T10 treatment. The MBN (immobilized nitrogen) was not affected. In the Shanxi soil, MBC, the populations of total bacteria, fungi, and N2-fixing bacteria, and NH(+)4-N concentration were not significantly affected by myclobutanil. The RB and MBN were decreased transitorily in the T10 treatment. The NO(-)3-N concentrations and the abundance of both AOA and AOB were erratically stimulated by myclobutanil. Regardless of whether stimulation or suppression occurred, the effects of myclobutanil on the two soil types were short term. In summary, myclobutanil had no long-term negative effects on the soil microbial biomass, respiration, and soil nitrogen transformations in the two types of soil, even at 10-fold the recommended dosage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Microbial respiration and kinetics of extracellular enzymes activities through rhizosphere and detritusphere at agricultural site

    Science.gov (United States)

    Löppmann, Sebastian; Blagodatskaya, Evgenia; Kuzyakov, Yakov

    2014-05-01

    detritivore communities in the soil. The kinetics (Km and Vmax) of four extracellular hydrolytic enzymes responsible for C- and phosphorous-cycle (β-glucosidase, β-xylosidase, β-cellobiohydrolase and acid phosphatase), microbial biomass, basal respiration (BR) and substrate-induced respiration (SIR) were measured in rhizosphere, detritusphere and control from 0 - 10 and 10 - 20 cm. The metabolic quotient (qCO2) was calculated as specific indicator for efficiency of microbial substrate utilization. We observed clear differences in enzymes activities at low and high concentrations of substrate. At substrate saturation enzyme activity rates of were significantly higher in rooted plots compared to litter amended plots, whereas at lower concentration no treatment effect could be found. The BR, SIR and qCO2 values were significantly higher at 0 - 10 cm of the planted treatment compared to litter and control plots, revealing a significantly higher respiration at lower efficiency of microbial substrate utilization in the rhizosphere. The Michaelis-Menten constant (Km) decreased with depth, especially for β-glucosidase, acid phosphatase and β-xylosidase, indicating higher substrate affinity of microorganisms in deeper soil and therefore different enzyme systems functioning. The substrate affinity factor (Vmax/Km) increased 2-fold with depth for various enzymes, reflecting a switch of predominantly occurring microbial strategies. Vmax/Km ratio indicated relative domination of zymogenous microbial communities (r-strategists) in 0 - 10 cm depth as compared with 10 - 20 cm depth where the K-strategists dominated.

  17. Microbial respiration and gene expression as a function of very low oxygen concentration

    DEFF Research Database (Denmark)

    Tiano, Laura

    recently, due to the lack of high-resolution methods for O2 concentration determination, several oxygen-related processes, such as aerobic respiration in pelagic aquatic ecosystems and in naturally oxygen poor waters (e.g. Oxygen Minimum Zones, OMZs), or the oxygen regulation of nitrification...... of these pure cultures were lower than found for natural communities of NOB (apparent Km values~ 1- 4 µM), but higher than the ones from the well-studied opportunistic NOB Nitrobacter. The expression of high-affinity terminal oxidases in these NOB could, however, not be confirmed. Overall the results of this Ph......Oxygen (O2) is a fundamental parameter for life. It not only profoundly influences the biogeochemical cycling on a global scale, but also deals with the regulation of metabolic processes at microbial level, in particular the transition between aerobic and anaerobic metabolisms. However, until...

  18. Dynamic relationships between microbial biomass, respiration, inorganic nutrients and enzyme activities: informing enzyme based decomposition models

    Directory of Open Access Journals (Sweden)

    Daryl L Moorhead

    2013-08-01

    Full Text Available We re-examined data from a recent litter decay study to determine if additional insights could be gained to inform decomposition modeling. Rinkes et al. (2013 conducted 14-day laboratory incubations of sugar maple (Acer saccharum or white oak (Quercus alba leaves, mixed with sand (0.4% organic C content or loam (4.1% organic C. They measured microbial biomass C, carbon dioxide efflux, soil ammonium, nitrate, and phosphate concentrations, and β-glucosidase (BG, β-N-acetyl-glucosaminidase (NAG, and acid phosphatase (AP activities on days 1, 3, and 14. Analyses of relationships among variables yielded different insights than original analyses of individual variables. For example, although respiration rates per g soil were higher for loam than sand, rates per g soil C were actually higher for sand than loam, and rates per g microbial C showed little difference between treatments. Microbial biomass C peaked on day 3 when biomass-specific activities of enzymes were lowest, suggesting uptake of litter C without extracellular hydrolysis. This result refuted a common model assumption that all enzyme production is constitutive and thus proportional to biomass, and/or indicated that part of litter decay is independent of enzyme activity. The length and angle of vectors defined by ratios of enzyme activities (BG/NAG versus BG/AP represent relative microbial investments in C (length, and N and P (angle acquiring enzymes. Shorter lengths on day 3 suggested low C limitation, whereas greater lengths on day 14 suggested an increase in C limitation with decay. The soils and litter in this study generally had stronger P limitation (angles > 45˚. Reductions in vector angles to < 45˚ for sand by day 14 suggested a shift to N limitation. These relational variables inform enzyme-based models, and are usually much less ambiguous when obtained from a single study in which measurements were made on the same samples than when extrapolated from separate studies.

  19. Effect of forest and soil type on microbial biomass carbon and respiration

    Science.gov (United States)

    Habashi, Hashem

    2016-09-01

    The aim of study was to evaluate the variation of soil microbial biomass carbon (Cmic) and microbial respiration (MR) in three types soil (Chromic Cambisols, Chromic Luvisols and Eutric Leptosols) of mixed beech forest (Beech- Hornbeam and Beech- Maple). Soil was randomly sampled from 0-10 cm layer (plant litter removed), 90 soil samples were taken. Cmic determined by the fumigation-extraction method and MR by closed bottle method. Soil Corg, Ntot and pH were measured. There are significant differences between the soil types concerning the Cmic content and MR. These parameters were highest in Chromic Cambisols following Chromic Luvisols, while the lowest were in Eutric Leptosols. A similar trend of Corg and Ntot was observed in studied soils. Two-way ANOVA indicated that soil type and forest type have significantly effect on the most soil characteristics. Chromic Cambisols shows a productive soil due to have the maximum Cmic, MR, Corg and Ntot. In Cambisols under Beech- Maple forest the Cmic value and soil C/N ratio were higher compared to Beech-Hornbeam (19.5 and 4.1 mg C g-1, and 16.3 and 3.3, respectively). This fact might be indicated that Maple litter had more easy decomposable organic compounds than Hornbeam. According to regression analysis, 89 and 68 percentage of Cmic variability could explain by soil Corg and Ntot respectively.

  20. Microbial respiration, but not biomass, responded linearly to increasing light fraction organic matter input: Consequences for carbon sequestration

    Science.gov (United States)

    Rui, Yichao; Murphy, Daniel V.; Wang, Xiaoli; Hoyle, Frances C.

    2016-10-01

    Rebuilding ‘lost’ soil carbon (C) is a priority in mitigating climate change and underpinning key soil functions that support ecosystem services. Microorganisms determine if fresh C input is converted into stable soil organic matter (SOM) or lost as CO2. Here we quantified if microbial biomass and respiration responded positively to addition of light fraction organic matter (LFOM, representing recent inputs of plant residue) in an infertile semi-arid agricultural soil. Field trial soil with different historical plant residue inputs [soil C content: control (tilled) = 9.6 t C ha‑1 versus tilled + plant residue treatment (tilled + OM) = 18.0 t C ha‑1] were incubated in the laboratory with a gradient of LFOM equivalent to 0 to 3.8 t C ha‑1 (0 to 500% LFOM). Microbial biomass C significantly declined under increased rates of LFOM addition while microbial respiration increased linearly, leading to a decrease in the microbial C use efficiency. We hypothesise this was due to insufficient nutrients to form new microbial biomass as LFOM input increased the ratio of C to nitrogen, phosphorus and sulphur of soil. Increased CO2 efflux but constrained microbial growth in response to LFOM input demonstrated the difficulty for C storage in this environment.

  1. Leaf litter breakdown, microbial respiration and shredder production in metal-polluted streams

    Science.gov (United States)

    Carlisle, D.M.; Clements, W.H.

    2005-01-01

    1. If species disproportionately influence ecosystem functioning and also differ in their sensitivities to environmental conditions, the selective removal of species by anthropogenic stressors may lead to strong effects on ecosystem processes. We evaluated whether these circumstances held for several Colorado, U.S.A. streams stressed by Zn. 2. Benthic invertebrates and chemistry were sampled in five second-third order streams for 1 year. Study streams differed in dissolved metal concentrations, but were otherwise similar in chemical and physical characteristics. Secondary production of leaf-shredding insects was estimated using the increment summation and size-frequency methods. Leaf litter breakdown rates were estimated by retrieving litter-bags over a 171 day period. Microbial activity on leaf litter was measured in the laboratory using changes in oxygen concentration over a 48 h incubation period. 3. Dissolved Zn concentrations varied eightfold among two reference and three polluted streams. Total secondary production of shredders was negatively associated with metal contamination. Secondary production in reference streams was dominated by Taenionema pallidum. Results of previous studies and the current investigation demonstrate that this shredder is highly sensitive to metals in Colorado headwater streams. Leaf litter breakdown rates were similar between reference streams and declined significantly in the polluted streams. Microbial respiration at the most contaminated site was significantly lower than at reference sites. 4. Our results supported the hypothesis that some shredder species contribute disproportionately to leaf litter breakdown. Furthermore, the functionally dominant taxon was also the most sensitive to metal contamination. We conclude that leaf litter breakdown in our study streams lacked functional redundancy and was therefore highly sensitive to contaminant-induced alterations in community structure. We argue for the necessity of simultaneously

  2. Soil microbial respiration (CO2) of natural and anthropogenically-transformed ecosystems in Moscow region, Russia

    Science.gov (United States)

    Ivashchenko, Kristina; Ananyeva, Nadezhda; Rogovaya, Sofia; Vasenev, Viacheslav

    2016-04-01

    The CO2 concentration in modern atmosphere is increasing and one of the most reasons of it is land use changing. It is related not only with soil plowing, but also with growing urbanization and, thereby, forming the urban ecosystems. Such conversion of soil cover might be affected by efflux CO2 from soil into atmosphere. The soil CO2 efflux mainly supplies by soil microorganisms respiration (contribution around 70-90%) and plant roots respiration. Soil microbial respiration (MR) is determined in the field (in situ) and laboratory (in vitro) conditions. The measurement of soil MR in situ is labour-consuming, and for district, region and country areas it is difficult carried. We suggest to define the MR of the upper highest active 10 cm mineral soil layer (in vitro) followed by the accounting of area for different ecosystems in large region of Russia. Soils were sampled (autumn, 2011) in natural (forest, meadow) and anthropogenically-transformed (arable, urban) ecosystems of Sergiev-Posad, Taldom, Voskresenk, Shatura, Serpukhov and Serbryanye Prudy districts in Moscow region. In soil samples (total 156) the soil MR (24 h, 22°C, 60% WHC) were measured after preincubation procedure (7 d., 22°C, 55% WHC). The soil MR ranged from 0.13 (urban) to 5.41 μg CO2-C g-1 h-1 (meadow), the difference between these values was 42 times. Then, the soil MR values (per unit soil weight) were calculated per unit soil area (1 m2), the layer thickness of which was 0.1 m (soil volume weight was equaled 1 g cm-3). The high MR values were noted for forests soil (832-1410 g CO2-C m-2 yr-1) of studied districts, and the low MR values were for arable and urban soils (by 1.6-3.2 and 1.3-2.7 times less compared to forests, respectively). The MR rate of urban soil in Voskresenk district was comparable to that of corresponding meadows and it was even higher (in average by 2.3 times) in Serpukhov district. The soil MR rate of studied cities was higher by 20%, than in corresponding arable soils

  3. Impact of Organic Amendments with and Without Mineral Fertilizers on Soil Microbial Respiration

    Science.gov (United States)

    Gilani, S. S.; Bahmanyar, M. A.

    A field experiment was conducted to study the effects of Sewage Sludge (SS), Municipal Waste Compost (MWC) and Vermicompost (VC) with and without chemical fertilizer (Urea, 50 kg ha-1 + Potassium sulfate, 100 kg ha-1 + Triple super phosphate, 127.5 kg ha-1) on Soil Microbial Respiration (SMR) and Total Organic Carbon (TOC) in a soil cropped to soybean. Experiment was arranged in a complete block design with three replications. Organic amendments were added to soil at rate of 0 (control treatment), 20 and 40 Mg ha-1. Furthermore each level of organic fertilizers with ½ normal of chemical fertilizer was also enriched. Soil samples were taken after one year of fertilization. Results illustrated that application of organic amendments increased TOC and SMR and soybean yield compared to control and chemical fertilizer treatments. Sewage sludge amended soils showed higher SMR, TOC and soybean yield than that of other organic amendment treatments. An increasing trend was observed in all studied parameters, as rates of application increased. All parameters were greater in treatments receiving a combination of chemical fertilizers and organic amendments (enriched treatments) compared to soils receiving organic amendments alone. Results obtained by discriminate analysis indicated that rates of application were more effective to create discriminating among treatments. This study showed that TOC was significantly correlated with SMR. Significant correlation was also observed between SMR and soybean yield.

  4. Respiration, microbial biomass and soil phosphatase activity in two agroecosystems and one forest in Turrialba, Costa Rica

    Directory of Open Access Journals (Sweden)

    Wuellins Durango

    2015-06-01

    Full Text Available In order to evaluate some microbiological and biochemical characteristics, a comparative study was carried out, as related to 3 different land uses in Ultisols located in Grano de Oro, Turrialba, Costa Rica. Three soil management systems were selected (two agroecosystems, coffee and coffee-banana and forest. In each farm, 4 composite soil samples were collected, on which microbial biomass and respiration, and phosphatase enzyme activity analysis were performed. The microbial biomass in forest was statistically higher (423 mg C kg-1 compared to those in agroecosystems coffee and coffee-banana (77 and 111 mg C kg-1 respectively. Microbial respiration did not show differences due to land management (580, 560 and 570 μg CO2 g-1.day-1 in coffee, coffee-banana and forest systems, respectively. It was also determined that the enzyme phosphatase activity in forest soils was statistically higher (4432 μg p-NP g-1.h-1. The data suggest that soil conditions in the forest favor greater microbial activity and phosphatase biomass, as compared to agricultural systems.

  5. Rapid microbial respiration of oil from the Deepwater Horizon spill in offshore surface waters of the Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Bethanie R; Reddy, Christopher M; Carmichael, Catherine A; Longnecker, Krista; Van Mooy, Benjamin A S [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole (United States); Camilli, Richard, E-mail: bvanmooy@whoi.edu [Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole (United States)

    2011-07-15

    The Deepwater Horizon oil spill was one of the largest oil spills in history, and the fate of this oil within the Gulf of Mexico ecosystem remains to be fully understood. The goal of this study-conducted in mid-June of 2010, approximately two months after the oil spill began-was to understand the key role that microbes would play in the degradation of the oil in the offshore oligotrophic surface waters near the Deepwater Horizon site. As the utilization of organic carbon by bacteria in the surface waters of the Gulf had been previously shown to be phosphorus limited, we hypothesized that bacteria would be unable to rapidly utilize the oil released from the Macondo well. Although phosphate was scarce throughout the sampling region and microbes exhibited enzymatic signs of phosphate stress within the oil slick, microbial respiration within the slick was enhanced by approximately a factor of five. An incubation experiment to determine hydrocarbon degradation rates confirmed that a large fraction of this enhanced respiration was supported by hydrocarbon degradation. Extrapolating our observations to the entire area of the slick suggests that microbes had the potential to degrade a large fraction of the oil as it arrived at the surface from the well. These observations decidedly refuted our hypothesis. However, a concomitant increase in microbial abundance or biomass was not observed in the slick, suggesting that microbial growth was nutrient limited; incubations amended with nutrients showed rapid increases in cell number and biomass, which supported this conclusion. Our study shows that the dynamic microbial community of the Gulf of Mexico supported remarkable rates of oil respiration, despite a dearth of dissolved nutrients.

  6. Soil fauna communities and microbial respiration in high Arctic tundra soils at Zackenberg, Northeast Greenland

    DEFF Research Database (Denmark)

    Sørensen, Louise I.; Holmstrup, Martin; Maraldo, Kristine;

    2006-01-01

    densities (naked amoeba and heterotrophic flagellates) were equal. Respiration rate of unamended soil was similar in soil from the three plots. However, a higher respiration rate increase in carbon + nutrient amended soil and the higher densities of soil fauna (with the exception of mites and protozoa...

  7. Soil respiration is not limited by reductions in microbial biomass during long-term soil incubations

    Science.gov (United States)

    Declining rates of soil respiration are reliably observed during long-term laboratory incubations, but the cause is uncertain. We explored different controls on soil respiration during long-term soil incubations. Following a 707 day incubation (30 C) of soils from cultivated and forested plots at Ke...

  8. Soil ecology of a rock outcrop ecosystem: Abiotic stresses, soil respiration, and microbial community profiles in limestone cedar glades

    Science.gov (United States)

    Cartwright, Jennifer M.; Advised by Dzantor, E. Kudjo

    2015-01-01

    Limestone cedar glades are a type of rock outcrop ecosystem characterized by shallow soil and extreme hydrologic conditions—seasonally ranging from xeric to saturated—that support a number of plant species of conservation concern. Although a rich botanical literature exists on cedar glades, soil biochemical processes and the ecology of soil microbial communities in limestone cedar glades have largely been ignored. This investigation documents the abiotic stress regime of this ecosystem (shallow soil, extreme hydrologic fluctuations and seasonally high soil surface temperatures) as well as soil physical and chemical characteristics, and relates both types of information to ecological structures and functions including vegetation, soil respiration, and soil microbial community metabolic profiles and diversity. Methods used in this investigation include field observations and measurements of soil physical and chemical properties and processes, laboratory analyses, and microbiological assays of soil samples.

  9. Microbial biomass and basal respiration in Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

    Directory of Open Access Journals (Sweden)

    E. Abakumov

    2014-03-01

    Full Text Available Antarctica is the unique place for pedological investigations. Soils of Antarctica have been studied intensively during the last century. Antarctic logistic provides the possibility to scientists access the terrestrial landscapes mainly in the places of polar stations. That is why the main and most detailed pedological investigations were conducted in Mc Murdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann hills and Schirmacher Oasis. Investigations were conducted during the 53rd and 55th Russian Antarctic expeditions on the base of soil pits and samples collected in Sub-Antarctic and Antarctic regions. Soils of diverse Antarctic landscapes were studied with aim to assess the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. The investigation conducted shows that soils of Antarctic are quite different in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod organo-mineral horizons as well as the upper organic layer. The most developed organic layers were revealed in peat soils of King-George Island, where its thickness reach even 80 cm. These soils as well as soils under guano are characterized by the highest amount of total organic carbon (TOC 7.22–33.70%. Coastal and continental soils of Antarctic are presented by less developed Leptosols, Gleysols, Regolith and rare Ornhitosol with TOC levels about 0.37–4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones which can be interpreted as result of higher amounts of fresh organic remnants in organic and organo-mineral horizons. Also the soils of King-George island have higher portion of microbial biomass (max 1.54 mg g−1 than coastal (max 0.26 mg g−1 and continental (max 0.22 mg g−1 Antarctic soils. Sub-Antarctic soils mainly differ from Antarctic ones in increased organic layers thickness and total

  10. Are variations in heterotrophic soil respiration related to changes in substrate availability and microbial biomass carbon in the subtropical forests?

    Science.gov (United States)

    Wei, Hui; Chen, Xiaomei; Xiao, Guoliang; Guenet, Bertrand; Vicca, Sara; Shen, Weijun

    2015-12-01

    Soil temperature and moisture are widely-recognized controlling factors on heterotrophic soil respiration (Rh), although they often explain only a portion of Rh variability. How other soil physicochemical and microbial properties may contribute to Rh variability has been less studied. We conducted field measurements on Rh half-monthly and associated soil properties monthly for two years in four subtropical forests of southern China to assess influences of carbon availability and microbial properties on Rh. Rh in coniferous forest was significantly lower than that in the other three broadleaf species-dominated forests and exhibited obvious seasonal variations in the four forests (P carbon (DOC) were significantly important to Rh variations, but the effect of DOC content on Rh was confounded with temperature, as revealed by partial mantel test. Microbial biomass carbon (MBC) was significantly related to Rh variations across forests during the warm season (P = 0.043). Our results suggest that DOC and MBC may be important when predicting Rh under some conditions, and highlight the complexity by mutual effects of them with environmental factors on Rh variations.

  11. Soil Temperature and Moisture Effects on Soil Respiration and Microbial Community Abundance

    Science.gov (United States)

    2015-04-13

    we assessed their abundance. Commonly, the response of ammonia oxidizers (Avrahami and Bohannan 2007), nitrifiers, and denitrifiers (Stres et al...snowfall. Soil Biology and Biochemistry 57:217–227. Avrahami, S., and B. J. M. Bohannan. 2007. Response of Nitrosospira sp. Strain AF-like ammonia ...Sullivan, and N. C. van Gestel. 2011. The temperature responses of soil respiration in deserts: a seven desert synthesis . Biogeochemistry 103:71–90

  12. Impact of different tillage treatments on soil respiration and microbial activity for different agricultural used soils in Austria

    Science.gov (United States)

    Klik, Andreas; Scholl, Gerlinde; Baatar, Undrakh-Od

    2015-04-01

    Soils can act as a net sink for sequestering carbon and thus attenuating the increase in atmospheric carbon dioxide if appropriate soil and crop management is applied. Adapted soil management strategies like less intensive or even no tillage treatments may result in slower mineralization of soil organic carbon and enhanced carbon sequestration. In order to assess the impact of different soil tillage systems on carbon dioxide emissions due to soil respiration and on soil biological activity parameters, a field study of three years duration (2007-2010)has been performed at different sites in Austria. Following tillage treatments were compared: 1) conventional tillage (CT) with plough with and without cover crop during winter period, 2) reduced tillage (RT) with cultivator with cover crop, and 3) no-till (NT) with cover crop. Each treatment was replicated three times. At two sites with similar climatic conditions but different soil textures soil CO2 efflux was measured during the growing seasons in intervals of one to two weeks using a portable soil respiration system consisting of a soil respiration chamber attached to an infrared gas analyzer. Additionally, concurrent soil temperature and soil water contents of the top layer (0-5 cm)were measured. For these and additional three other sites with different soil and climatic conditions soil samples were taken to assess the impact of tillage treatment on soil biological activity parameters. In spring, summer and autumn samples were taken from each plot at the soil depth of 0-10, 10-20, and 20-30 cm to analyze soil microbial respiration (MR), substrate induced respiration (SIR), beta-glucasidase activity (GLU) and dehydrogenase (BHY). Samples were sieved (2 mm) and stored at 4 °C in a refrigerator. Analyses of were performed within one month after sampling. The measurements show a high spatial variability of soil respiration data even within one plot. Nevertheless, the level of soil carbon dioxide efflux was similar for

  13. Assessing the use of delta C-13 natural abundance in separation of root and microbial respiration in a Danish beech (¤Fagus Sylvatica¤ L.) forest

    DEFF Research Database (Denmark)

    Formanek, P.; Ambus, P.

    2004-01-01

    Our understanding of forest biosphere-atmosphere interactions is fundamental for predicting forest ecosystem responses to climatic changes. Currently, however, our knowledge is incomplete partly due to inability to separate the major components of soil CO2 effluxes, viz. root respiration, microbi...

  14. An optical method for carbon dioxide isotopes and mole fractions in small gas samples: tracing microbial respiration from soil, litter, and lignin.

    Science.gov (United States)

    Steven J. Hall; Wenjuan Huang; Kenneth Hammel

    2017-01-01

    RATIONALE: Carbon dioxide isotope (Δ13C value) measurements enable quantification of the sources of soil microbial respiration, thus informing ecosystem C dynamics. Tunable diode lasers (TDLs) can precisely measure CO2 isotopes at low cost and high throughput, but are seldom used for small samples (≤5 mL). We developed a...

  15. Microbial respiration activities correlated to sequentially separated, particulate and water-soluble organic matter fractions from arable and forest topsoils

    Science.gov (United States)

    Kaiser, M.; Wirth, S.; Ellerbrock, R.; Sommer, M.

    2009-12-01

    Michael Kaiser1, Stephan Wirth2, Ruth H. Ellerbrock3, Michael Sommer3,4 1University of California Merced, Natural Science, 4225 N. Hospital Rd., Atwater, CA 95301 2,3 Leibniz-Center for Agricultural Research (ZALF) e. V. 2 Institute of Landscape Matter Dynamics 3 Institute of Soil Landscape Research Eberswalder Str. 84, D-15374 Muencheberg, Germany 4University of Potsdam, Institute of Geoecology, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany Microbial respiration activities correlated to sequentially separated, particulate and water-soluble organic matter fractions from arable and forest topsoils Microbial decomposition of soil organic matter (SOM) accounts for roughly half of CO2 evolution from vegetated soil surfaces and plays a crucial role in the ability of soil to mitigate the greenhouse effect. The separation and identification of labile (i.e., easily decomposable) organic matter (OM) fractions from bulk SOM is of particular importance for a mechanistic understanding of microbial decomposition processes and for predicting the response of SOM to changes in land use, management, and climate. This work aimed to reveal differences in the relevance of particulate as well as water-soluble organic matter (OM) fractions from topsoils to the easily biodegradable soil organic matter (SOM). We selected eight paired sites with quite different soil types (Udorthent, Paleudalf, Glossudalf, Aquept, Hapludalf, Aquert, Udert, Haplorthod) and soil properties (e.g., clay content: 28 to 564 g kg-1). For each of these sites, we took samples from adjacent arable and forest topsoils. Physically uncomplexed, macro-, and micro-aggregate-occluded organic particle, as well as water-soluble OM fractions were sequentially separated by a combination of electrostatic attraction, ultrasonic treatment, density separation, sieving, and water extraction. The easily biodegradable SOM of the topsoil samples was determined by measuring microbial respiration during a short-term incubation

  16. Responses of soil microbial biomass and soil respiration to rainfall%土壤微生物量和土壤呼吸对降雨的响应

    Institute of Scientific and Technical Information of China (English)

    苏慧敏; 李叙勇; 欧阳扬

    2011-01-01

    To discern the responds of soil microbial biomass and soil respiration to rainfall, we continuously determined changes in soil microbial biomass and soil respiration after and before rainfall. The results showed that soil microbial biomass and soil respiration increased sharply after rainfall and then reduced gradually. Comparing the values after and before for the first rainfall, the soil microbial biomass carbon, nitrogen and soil respiration increased 3.08, 2.83 and 2.50 times, respectively. Comparing the values after and before for the second rainfall, the soil microbial biomass carbon, nitrogen and soil respiration increased 1.08, 1.63 and 1.68 times, respectively. The surge effect of soil microbial biomass and soil respiration lasted only one day. The third rainfall was only 0.40 mm, the range of soil microbial biomass and soil respiration was unconspicuous.%本研究在北京门头沟龙凤岭水土保持科技示范园内进行,降雨前后连续测定土壤微生物量和土壤呼吸,探讨土壤微生物量和土壤呼吸对降雨的响应.结果表明:干旱的土壤降雨后土壤微生物量和土壤呼吸骤升随后逐渐衰减,第1场降雨后土壤微生物量碳、氮和土壤呼吸分别是干旱期的3.08、2.83、2.50倍,第2场降雨后土壤微生物量碳、氮和土壤呼吸分别是干旱期的1.08、1.63、1.68倍,降雨使土壤微生物量和土壤呼吸产生的激增效应仅持续1d.第3场降雨量仅为0.40 mm,土壤微生物量和土壤呼吸增加的幅度不是很大.

  17. Seasonal Variation in Soil Microbial Biomass, Bacterial Community Composition and Extracellular Enzyme Activity in Relation to Soil Respiration in a Northern Great Plains Grassland

    Science.gov (United States)

    Wilton, E.; Flanagan, L. B.

    2014-12-01

    Soil respiration rate is affected by seasonal changes in temperature and moisture, but is this a direct effect on soil metabolism or an indirect effect caused by changes in microbial biomass, bacterial community composition and substrate availability? In order to address this question, we compared continuous measurements of soil and plant CO2 exchange made with an automatic chamber system to analyses conducted on replicate soil samples collected on four dates during June-August. Microbial biomass was estimated from substrate-induced respiration rate, bacterial community composition was determined by 16S rRNA amplicon pyrosequencing, and β-1,4-N-acetylglucosaminidase (NAGase) and phenol oxidase enzyme activities were assayed fluorometrically or by absorbance measurements, respectively. Soil microbial biomass declined from June to August in strong correlation with a progressive decline in soil moisture during this time period. Soil bacterial species richness and alpha diversity showed no significant seasonal change. However, bacterial community composition showed a progressive shift over time as measured by Bray-Curtis dissimilarity. In particular, the change in community composition was associated with increasing relative abundance in the alpha and delta classes, and declining abundance of the beta and gamma classes of the Proteobacteria phylum during June-August. NAGase showed a progressive seasonal decline in potential activity that was correlated with microbial biomass and seasonal changes in soil moisture. In contrast, phenol oxidase showed highest potential activity in mid-July near the time of peak soil respiration and ecosystem photosynthesis, which may represent a time of high input of carbon exudates into the soil from plant roots. This input of exudates may stimulate the activity of phenol oxidase, a lignolytic enzyme involved in the breakdown of soil organic matter. These analyses indicated that seasonal change in soil respiration is a complex

  18. Shifts in the microbial community structure explain the response of soil respiration to land-use change but not to climate warming

    DEFF Research Database (Denmark)

    Nazaries, Loïc; Tottey, William; Robinson, Lucinda

    2015-01-01

    of this feedback response of Rs to global change. To identify the mechanisms of Rs response to land-use change and climate warming, we first investigated Rs from different land use types. Soil respiration was estimated seasonally from four different Scottish land uses: moorland, birch woodland, grassland and pine......Soil stores more carbon (C) than plants and atmosphere combined and it is vulnerable to increased microbial respiration under projected global changes including land-use change and future climate scenarios (mainly elevated temperature). Land-use change is known to have a direct impact on soil...... organic C and soil respiration (Rs) but the mechanisms that drive these changes remain debatable. Similarly, recent studies and simulation models predict that Rs will respond positively to projected climate warming. However, there are significant uncertainties in the magnitude and mechanisms...

  19. Microbial Reduction of Chromate in the presence of Nitrate by Three Nitrate Respiring Organisms.

    Directory of Open Access Journals (Sweden)

    Peter eChovanec

    2012-12-01

    Full Text Available A major challenge for the bioremediation of toxic metals is the co-occurrence of nitrate, as it can inhibit metal transformation. Geobacter metallireducens, Desulfovibrio desulfuricans, and Sulfurospirillum barnesii are three soil bacteria that can reduce chromate (Cr(VI and nitrate, and may be beneficial for developing bioremediation strategies. All three organisms respire through dissimilatory nitrate reduction to ammonia (DNRA, employing different nitrate reductases but similar nitrite reductase (Nrf. G. metallireducens reduces nitrate to nitrite via the membrane bound nitrate reductase (Nar, while S. barnesii and D. desulfuricans strain 27774 have slightly different forms of periplasmic nitrate reductase (Nap. We investigated the effect of DNRA growth in the presence of Cr(VI in these three organisms and the ability of each to reduce Cr(VI to Cr(III, and each organisms responded differently. Growth of G. metallireducens on nitrate was completely inhibited by Cr(VI. Cultures of D. desulfuricans on nitrate media was initially delayed (48 h in the presence of Cr(VI, but ultimately reached comparable cell yields to the non-treated control. This prolonged lag phase accompanied the transformation of Cr(VI to Cr(III. Viable G. metallireducens cells could reduce Cr(VI, whereas Cr(VI reduction by D. desulfuricans during growth, was mediated by a filterable and heat stable extracellular metabolite. S. barnesii growth on nitrate was not affected by Cr(VI, and Cr(VI was reduced to Cr(III. However, Cr(VI reduction activity in S. barnesii, was detected in both the cell free spent medium and cells, indicating both extracellular and cell associated mechanisms. Taken together, these results have demonstrated that Cr(VI affects DNRA in the three organisms differently, and that each have a unique mechanism for Cr(VI reduction.

  20. Spatial-temporal variability of the microbial respiration at the regional scale: comparison of field and laboratory approaches

    Science.gov (United States)

    Vasenev, Viacheslav; Stoorvogel, Jetse; Ananyeva, Nadezhda D.; Valentini, Riccardo

    2013-04-01

    Regional carbon assessments are increasingly important. Soil respiration is a predominant carbon efflux of terrestrial ecosystems. The total carbon efflux from soils includes autotrophic respiration of root systems and heterotrophic microbial respiration (MR). MR usually refers to 60-80% of the total efflux and thus plays a key role in regional carbon balance. Quite a few studies report high sensitivity of MR to climate conditions and land-use. Different approaches to analyze MR exist. The methods differ in the procedures to consider space and time variability. We evaluated two approaches to assess MR variability. One approach uses field measurements on a limited number of locations with chambers. The other approach samples more intensively and derives basal respiration (BR) from measurements under standard conditions in the laboratory. The chamber approach includes periodic measurements at a limited number of sites. As such, the methodology provides appropriate information on temporal dynamics. Spatial variability although, is underrepresented .. In our case chambers were mounted in forest, cropland and urban sites (n=48) located in the north of Moscow city. Roots were removed and geotextile (1 micron mesh) bags were inserted in soil to segregate MR. The flux was measured weekly by Li-6400-XT from July till September 2012. In contrast, standardized BR techniques minimize the diversity of initial conditions. This allows to increase the number of observations considerably. However, the temporal variance is avoided. BR was analyzed in mixed topsoil (0-10 cm) and subsoil (10-150 cm) samples (n=182) collected in forest, cropland and urban sites from different bioclimatic zones of Moscow region. After preincubation (T=22°C, 55% water content, 7 days) soil MR (in μg ?O2-? g-1) was measured after incubating 2g soil with 0.2 μl distilled water as the rate of ?O2 production (22° ?, 24 h) by gas chromatography. Both approaches can be used to describe MR variability in

  1. High rates of sulfate reduction in a low-sulfate hot spring microbial mat are driven by a low level of diversity of sulfate-respiring microorganisms

    DEFF Research Database (Denmark)

    Dillon, Jesse G; Fishbain, Susan; Miller, Scott R

    2007-01-01

    The importance of sulfate respiration in the microbial mat found in the low-sulfate thermal outflow of Mushroom Spring in Yellowstone National Park was evaluated using a combination of molecular, microelectrode, and radiotracer studies. Despite very low sulfate concentrations, this mat community...... was shown to sustain a highly active sulfur cycle. The highest rates of sulfate respiration were measured close to the surface of the mat late in the day when photosynthetic oxygen production ceased and were associated with a Thermodesulfovibrio-like population. Reduced activity at greater depths...... was correlated with novel populations of sulfate-reducing microorganisms, unrelated to characterized species, and most likely due to both sulfate and carbon limitation....

  2. Soil plus root respiration and microbial biomass following water, nitrogen, and phosphorus application at a high arctic semi desert

    DEFF Research Database (Denmark)

    Illeris, Lotte; Michelsen, Anders; Jonasson, Sven Evert

    2003-01-01

    CO2 emmision, Decomposition, Microbial biomass carbon, Soil organic matter, Tundra, Water and nutrient limitation......CO2 emmision, Decomposition, Microbial biomass carbon, Soil organic matter, Tundra, Water and nutrient limitation...

  3. Soil plus root respiration and microbial biomass following water, nitrogen, and phosphorus application at a high arctic semi desert

    DEFF Research Database (Denmark)

    Illeris, Lotte; Michelsen, Anders; Jonasson, Sven Evert

    2003-01-01

    CO2 emmision, Decomposition, Microbial biomass carbon, Soil organic matter, Tundra, Water and nutrient limitation......CO2 emmision, Decomposition, Microbial biomass carbon, Soil organic matter, Tundra, Water and nutrient limitation...

  4. Long term impacts of CMC/nZVI amendment injection on organohalide-respiring microbial communities at a chlorinated solvent field site

    Science.gov (United States)

    Kocur, C. M.; Lomheim, L.; Boparai, H. K.; Chowdhury, A. I.; Weber, K.; Austrins, L. M.; Sleep, B.; O'Carroll, D. M.; Edwards, E.

    2014-12-01

    Injection of carboxymethyl-cellulose stabilized nanoscale Zero Valent Iron (CMC/nZVI) has received significant attention in the last decade as an emerging alternative for in-situ remediation of chlorinated solvents and other recalcitrant compounds. There has also been some indication that injection of nZVI will create conditions that will stimulate in-situ microbial populations, leading to further contaminant degradation. Carboxy-methyl cellulose (CMC) is commonly used for nZVI synthesis as it provides steric stabilization for the nanoparticles, however, the CMC is equally important as a subsurface amendment as it may act as a fermentable substrate for microorganisms in-situ. In this study, microbial communities were monitored over a 2.5 year period following the injection of CMC/nZVI at a chlorinated solvent remediation site. Dehalococcoides spp. genetic markers and vinyl chloride reductase genes (vcrA) were targeted in the 16s RNA using quantitative polymerase chain reaction (qPCR). This analysis was complimented with a suite of aqueous chlorinated ethene, ethane, and methane compounds to monitor degradation. Following the injection of CMC/nZVI a decline of parent chlorinated compound concentrations was observed as well as the emergence of daughter products. A period of abiotic nZVI oxidation is believed to be responsible for a portion of the degradation at the site, however, a prolonged period of contaminant degradation followed and is believed to be the result of organohalide-respiring microorganisms native to the site. Further analysis was performed on the microbial samples using 454 pyrotag sequencing of amplified 16S rRNA genes to obtain the genetic profile of the microbial community. Of particular interest within this large genomic profile is the characterization of the stable population of important organohalide-respiring microorganisms on site. Results suggest that there is a distinctly different response in the organohalide-respiring microbial community

  5. Microbial biomass and basal respiration of selected Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

    Science.gov (United States)

    Abakumov, E.; Mukhametova, N.

    2014-07-01

    Antarctica is a unique place for soil, biological, and ecological investigations. Soils of Antarctica have been studied intensively during the last century, when different national Antarctic expeditions visited the sixth continent with the aim of investigating nature and the environment. Antarctic investigations are comprised of field surveys mainly in the terrestrial landscapes, where the polar stations of different countries are situated. That is why the main and most detailed soil surveys were conducted in the McMurdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann Hills and the Schirmacher Oasis. Our investigations were conducted during the 53rd and 55th Russian Antarctic expeditions in the base of soil pits, and samples were collected in Sub-Antarctic and Antarctic regions. Sub-Antarctic or maritime landscapes are considered to be very different from Antarctic landscapes due to differing climatic and geogenic conditions. Soils of diverse zonal landscapes were studied with the aim of assessing the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. This investigation shows that Antarctic soils are quite diverse in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod) organo-mineral horizons as well as by an upper organic layer. The most developed organic layers were revealed in peat soils of King George Island, where its thickness reach, in some cases, was 80 cm. These soils as well as soils formed under guano are characterized by the highest amount of total organic carbon (TOC), between 7.22 and 33.70%. Coastal and continental Antarctic soils exhibit less developed Leptosols, Gleysols, Regolith and rare Ornhitosol, with TOC levels between 0.37 and 4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones, which can be interpreted as a result of higher amounts of fresh organic

  6. Heterotrophic Soil Respiration in Warming Experiments: Using Microbial Indicators to Partition Contributions from Labile and Recalcitrant Soil Organic Carbon. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Bradford, M A; Melillo, J M; Reynolds, J F; Treseder, K K; Wallenstein, M D

    2010-06-10

    The central objective of the proposed work was to develop a genomic approach (nucleic acid-based) that elucidates the mechanistic basis for the observed impacts of experimental soil warming on forest soil respiration. The need to understand the mechanistic basis arises from the importance of such information for developing effective adaptation strategies for dealing with projected climate change. Specifically, robust predictions of future climate will permit the tailoring of the most effective adaptation efforts. And one of the greatest uncertainties in current global climate models is whether there will be a net loss of carbon from soils to the atmosphere as climate warms. Given that soils contain approximately 2.5 times as much carbon as the atmosphere, a net loss could lead to runaway climate warming. Indeed, most ecosystem models predict that climate warming will stimulate microbial decomposition of soil carbon, producing such a positive feedback to rising global temperatures. Yet the IPCC highlights the uncertainty regarding this projected feedback. The uncertainty arises because although warming-experiments document an initial increase in the loss of carbon from soils, the increase in respiration is short-lived, declining to control levels in a few years. This attenuation could result from changes in microbial physiology with temperature. We explored possible microbial responses to warming using experiments and modeling. Our work advances our understanding of how soil microbial communities and their activities are structured, generating insight into how soil carbon might respond to warming. We show the importance of resource partitioning in structuring microbial communities. Specifically, we quantified the relative abundance of fungal taxa that proliferated following the addition of organic substrates to soil. We added glycine, sucrose, cellulose, lignin, or tannin-protein to soils in conjunction with 3-bromo-deoxyuridine (BrdU), a nucleotide analog. Active

  7. Water organic pollution and eutrophication influence soil microbial processes, increasing soil respiration of estuarine wetlands: site study in jiuduansha wetland.

    Science.gov (United States)

    Zhang, Yue; Wang, Lei; Hu, Yu; Xi, Xuefei; Tang, Yushu; Chen, Jinhai; Fu, Xiaohua; Sun, Ying

    2015-01-01

    Undisturbed natural wetlands are important carbon sinks due to their low soil respiration. When compared with inland alpine wetlands, estuarine wetlands in densely populated areas are subjected to great pressure associated with environmental pollution. However, the effects of water pollution and eutrophication on soil respiration of estuarine and their mechanism have still not been thoroughly investigated. In this study, two representative zones of a tidal wetland located in the upstream and downstream were investigated to determine the effects of water organic pollution and eutrophication on soil respiration of estuarine wetlands and its mechanism. The results showed that eutrophication, which is a result of there being an excess of nutrients including nitrogen and phosphorus, and organic pollutants in the water near Shang shoal located upstream were higher than in downstream Xia shoal. Due to the absorption and interception function of shoals, there to be more nitrogen, phosphorus and organic matter in Shang shoal soil than in Xia shoal. Abundant nitrogen, phosphorus and organic carbon input to soil of Shang shoal promoted reproduction and growth of some highly heterotrophic metabolic microorganisms such as β-Proteobacteria, γ-Proteobacteria and Acidobacteria which is not conducive to carbon sequestration. These results imply that the performance of pollutant interception and purification function of estuarine wetlands may weaken their carbon sequestration function to some extent.

  8. 耕作措施对东北黑土微生物呼吸的影响%Effect of Conservation Tillage on Microbial Respiration of Black Soil

    Institute of Scientific and Technical Information of China (English)

    贾淑霞; 孙冰洁; 梁爱珍; 陈学文; 张士秀; 魏守才; 刘四义; 陈升龙; 张晓平

    2015-01-01

    耕作处理只改变了5 cm的Q10值,免耕比秋翻高10.8%。土壤微生物呼吸速率与土壤温度、水分混合回归模型能更好地反应其变化规律,解释土壤微生物呼吸速率变异的65%(秋翻)和81%(免耕)。【结论】免耕增加了表层(0—5 cm)的SOC含量,从而使得该土层的土壤微生物量碳和活性增加,但是由于免耕处理增加0—30 cm 土层SOC含量的加权平均值,因此相对于传统的耕作措施(秋翻),免耕有利于SOC含量的增加。%Objective] In this study, soil microbial activity and biomass carbon under 13-year conservation tillage (no-till) were assessed in a black soil agro-ecosystem in northeast China in order to determine the effect of tillage treatment on soil organic carbon and soil microbial biomass, which would provide a theoretical basis for valuing the ‘sink’ or ‘source’ function of soil carbon pool.[Method] The present study was conducted as part of a long term tillage experiment on the continuous maize (Zea mays L.), tillage treatments consisted of no-tillage (NT), and mouldboard plough (MP). The NT treatment had no soil disturbance except planting, crop residues were left on soil surface after harvest. The MP treatment included one fall mouldboard plough (about 15 cm in depth) after maize harvest, one disking (7.5 to 10 cm in depth) in spring and field cultivation (ridging in June). Soil respiration without roots represented soil microbial respiration, which was measured biweekly from 14 June 2012 to 25 September 2013 using LI-8100 automated soil CO2 flux system (LI-COR Inc., Lincoln, NE, USA), soil microbial biomass and the number of colony forming units of bacteria (cfub), fungi (cfuf), and actinomyces (cfua) were measured during the soil microbial respiration was the highest.[Result] It was found that the range of soil microbial respiration was 0.42-3.35μmolCO2·m-2·s-1under NT and 0.48-3.24μmolCO2·m-2·s-1under MP during growing season, the average soil

  9. An Experimental Study on What Controls the Ratios of 18O/16O and 17O/16O of O2 During Microbial Respiration

    Science.gov (United States)

    Stolper, D. A.; Ward, B. B.; Fischer, W. W.; Bender, M. L.

    2015-12-01

    18O/16O and 17O/16O ratios of atmospheric and dissolved oceanic O2 are key biogeochemical tracers of total photosynthesis and respiration on global to local length scales and glacial/interglacial time scales (Luz et al., 1999). Critical to the use of these ratios as biogeochemical tracers is knowledge of how they are affected by production, consumption, and transport of O2. We present new measurements of O2 respiration by E. coli and N. oceanus, an ammonia oxidizing bacterium, to test three assumptions of isotopically enabled models of the O2 cycle: (i) laboratory-measured respiratory 18O/16O isotope effects (18α) of microorganisms are constant under all experimental and natural conditions (e.g., temperature and growth rate); (ii) the respiratory 'mass law' relationship between 18O/16O and 17O/16O [17α = (18α)β] is universal; and (iii) 18α and β for aerobic ammonia and organic carbon oxidation are identical. For E. coli, we find that both 18α and β are variable. From 37°C to 15°C, 18α varies linearly with temperature from 17 to 14‰, and β varies linearly from 0.513 to 0.508. 18α and β do not appear to vary with growth rate (as tested using different carbon sources). Both 18α and β are lower than previous observations for bacteria: 18α = 17-20‰ (Kiddon et al., 1993) and β = 0.515 (Luz and Barkan, 2005). We were able to simulate the observed temperature dependence of 18α and β using a model of respiration with two isotopically discriminating steps: O2 binding to cytochrome bo oxidase (the respiratory enzyme) and reduction of O2 to H2O. Finally, initial results on N. oceanus suggest it has similar values for 18α and β as previously studied aerobic bacteria that consume organic carbon, providing the first support for assumption (iii). Based on these results, isotopically constrained biogeochemical models of O2 cycling may need to consider a temperature dependence for 18α and β for microbial respiration. For example, these results may

  10. Syntrophic interactions between H2-scavenging and anode-respiring bacteria can improve current density in microbial electrochemical cells

    Science.gov (United States)

    High current density of 10.0-14.6 A/m2 and COD removal up to 96% were obtained in a microbial electrochemical cell (MEC) fed with digestate at hydraulic retention time (HRT) of 4d and 8d. Volatile fatty acids became undetectable in MEC effluent (HRT 8d), except for trivial acetat...

  11. RESPIRACIÓN MICROBIAL Y DE RAÍCES EN SUELOS DE BOSQUES TROPICALES PRIMARIOS Y SECUNDARIOS (PORCE, COLOMBIA MICROBIAL AND ROOT RESPIRATION IN SOILS OF TROPICAL PRIMARY AND SECONDARY FORESTS ( PORCE, COLOMBIA

    Directory of Open Access Journals (Sweden)

    Álvaro Andrés Ramírez Palacio

    2008-06-01

    Full Text Available Los suelos son el mayor reservorio de carbono en los ecosistemas terrestres y a su vez la mayor fuente de CO2 atmosférico, el cual es producido mediante un proceso denominado respiración del suelo. El objetivo de este trabajo fue estimar las tasas de respiración del suelo y sus componentes (respiración de raíces y de microorganismos, y evaluar el control que sobre las tasas de emisión de CO2 ejercen factores como la humedad y la temperatura del suelo, en bosques primarios (BP y secundarios (BS de la región de Porce, Colombia. Para este fin se midió la emisión de CO2 del suelo durante un año, en 10 parcelas con una cámara de respiración de suelo conectada a un analizador de gases infrarrojo. La tasa promedia anual de respiración fue 15,91 (0,71 e.e. y 14,03 (0,75 e.e. C t · ha-1 · año-1 en BP y BS, respectivamente. La respiración de las raíces representó casi la mitad de la respiración total en ambos tipos de bosque. La variación estacional de la respiración total estuvo asociada principalmente a las diferencias de humedad del suelo. Los resultados sugieren que desde el suelo de los bosques tropicales se emiten cantidades considerables de carbono hacia la atmósfera, y que factores ambientales como la humedad y la temperatura del suelo, ejercen un control importante sobre las tasas de emisión. De este modo, un incremento en la emisión de CO2 desde los suelos de estos ecosistemas, en respuesta a los cambios ambientales, puede tener grandes implicaciones en el balance global del carbono.Soils are the largest carbon pool of terrestrial ecosystems as well as the largest source of atmospheric CO2 through a process called soil respiration. The purpose of this study was to estimate the soil respiration rates and its components (root and microbial respiration, and to evaluate the control of environmental factors such as soil humidity and temperature on emission rates of CO2 in primary (PF and secondary forests (SF of the Porce

  12. Effect of Fertilization on Soil Respiration and Microbial Biomass Carbon during Maize Growth Period%玉米生长过程中施肥对土壤呼吸和微生物量碳的影响

    Institute of Scientific and Technical Information of China (English)

    葛高飞; 梁永超

    2011-01-01

    The change disciplinarian of soil respiration and microbial biomass C during maize growth were studied to illuminate relation between disciplinarian and fertilization, and between disciplinarian and soil types. The effects of maize growth and fertilization on soil respiration and microbial biomass C were investigated in representative soil of south and north China (black and red soil) in pot experiment. The results showed that soil respiration and microbial biomass C changed with different growth stages, fertilization treatments and soil textures. The effect of maize growth on contents of soil total N and organic matter, and soil respiration in black soil was not obvious, but soil microbial biomass C increased with maize growth, and reached maximum at maize large bugle stage. However, soil total N, organic matter, soil respiration and microbial biomass C in red soil increased with maize growth, and showed maximum at maize large bugle stage. During the maize growth, organic manure treatments increased soil respiration and microbial biomass C in black and red soil, but inorganic fertilizers treatments had a little effect on them. Fertilization treatments showed no significant effects on soil total N and organic matter content in black soil, however, significantly increased soil respiration and microbial biomass C content in red soil. Besides, organic manure treatments decreased soil microbial metabolic quotient, but inorganic fertilizers treatments increased soil microbial metabolic quotient both in Black soil and in red soil. In conclusion, not only maize growth stages and fertilization treatments but also soil texture influenced soil respiration and microbial biomass C content.%为了阐明玉米生长中土壤呼吸和微生物生物量碳的变化规律与施肥和土壤类型间的关系,运用盆栽试验研究了玉米生长和施肥处理对中国南北典型土壤(黑土和红壤)的土壤呼吸和微生物生物量碳的影响.结果表明,施肥条件下,

  13. Ecosystem function in oil sands wetlands : rates of detrital decomposition, moss growth, and microbial respiration in oilsands wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Wytrykush, C. [Windsor Univ., ON (Canada); Hornung, J. [Petro-Canada, Calgary, AB (Canada)

    2007-07-01

    A study was conducted in which leaf litter breakdown and biomass accrual in 31 reference and oilsands affected (OSPM) wetlands in Northeastern Alberta was examined. The purpose was to determine how the decomposition of dead plant matter controls the primary productivity in wetlands. The data collected from this study will provide information about carbon flow and dynamics in oilsands affected wetlands. The study involved the investigation of wetlands that contrasted in water origin (OSPM vs. reference), sediment origin (OSPM vs. natural), sediment organic content and age. Mesh bags containing 5 g of dried Typha (cattail) or 20 g of damp moss were placed into 31 wetlands in order to monitor the rate at which biomass was lost to decomposition, as measured by changes in dry mass. After 1 year, moss growth was found to be greatest in younger wetlands with natural sediments. Cattail decomposition was found to be slower in wetlands containing OSPM water than that in reference wetlands. Preliminary analysis of respiration rates of biota associated with decomposing cattail indicate that the amount of oxygen consumed is not affected by wetland water source, sediment source, level of initial sediment organic content, or age.

  14. Effects of fumigation with metam-sodium on soil microbial biomass, respiration, nitrogen transformation, bacterial community diversity and genes encoding key enzymes involved in nitrogen cycling.

    Science.gov (United States)

    Li, Jun; Huang, Bin; Wang, Qiuxia; Li, Yuan; Fang, Wensheng; Han, Dawei; Yan, Dongdong; Guo, Meixia; Cao, Aocheng

    2017-11-15

    Metam-sodium (MS) is widely used as a soil pre-plant fumigant as methyl bromide is phased out of agriculture. However, the information about how fumigation with MS affects the soil microbial community is still limited. In this study, a 66-day-long experiment was conducted to ascertain the effects of MS on soil substrate-induced respiration (SIR), microbial biomass nitrogen (MBN), NH4(+)-N and NO3(-)-N concentrations, as well as the abundance of the total bacteria and fungi and the expression of genes involved in nitrogen cycling. In addition, 16S rRNA amplicon sequencing was used to investigate the effect of MS on the soil bacterial community. The half-lives of high and low doses of methyl isothiocyanate (MITC) are 10.51h and 9.93h, respectively. MS caused a short-term inhibition of SIR, MBN; had an accumulation effect on NH4(+)-N concentration in the short term; reduced the abundance of the total bacteria and fungi; and suppressed the expression of the nifH, AOA-amoA, anammox bacteria, nosZ, nirS, and narG. In addition, under the influence of MS, soil bacterial diversity decreased significantly in the long term, bacterial community structure was affected, and there was a shift in the predominant population; for example, some genera, such as Paenibacillus and Luteimonas, significantly increased in number. These changes in bacterial flora may be closely related to the growth of crops. Our study provides useful information for environmental safety assessments of MS in China. Copyright © 2017. Published by Elsevier B.V.

  15. Distribution of microbial biomass and the potential for anaerobic respiration in Hanford Site 300 Area subsurface sediment

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Xueju; Kennedy, David W.; Peacock, Aaron D.; McKinley, James P.; Resch, Charles T.; Fredrickson, Jim K.; Konopka, Allan

    2012-02-01

    Subsurface sediments were recovered from a 52 m deep borehole cored in the 300 Area of the Hanford Site in southeastern Washington State to assess the potential for biogeochemical transformation of radionuclide contaminants. Microbial analyses were made on 17 sediment samples traversing multiple geological units: the oxic coarse-grained Hanford formation (9-17.4 m), the oxic fine-grained upper Ringold Formation (17.7-18.1 m), and the reduced Ringold Formation (18.3-52m). Microbial biomass (measured as phospholipid) ranged from 7-974 pmols per g in discrete samples, with the highest numbers found in the Hanford formation. On average, strata below 17.4 m had 13-fold less biomass than those from shallower strata. The nosZ gene encoding nitrous oxide reductase had an abundance of 5-17% relative to total 16S rRNA genes below 18.3 m and <5% above 18.1 m. Most nosZ sequences were affiliated with Ochrobactrum anthropi (97% sequence similarity) or had a nearest neighbor of Achromobacter xylosoxidans (90% similarity). Passive multilevel sampling of groundwater geochemistry demonstrated a redox gradient in the 1.5 m region between the Hanford-Ringold formation contact and the Ringold oxic-anoxic interface. Within this zone, copies of the dsrA gene and Geobacteraceae had the highest relative abundance. The majority of dsrA genes detected near the interface were related to Desulfotomaculum sp.. These analyses indicate that the region just below the contact between the Hanford and Ringold formations is a zone of active biogeochemical redox cycling.

  16. 玉米和大豆秸秆还田对黑土微生物量及呼吸的影响%Effects of Corn and Soybean Residues Return on Microbial Biomass and Respiration in a Black Soil

    Institute of Scientific and Technical Information of China (English)

    刘四义; 贾淑霞; 张晓平; 陈学文; 张士秀; 孙冰洁; 陈升龙; 窦永静

    2014-01-01

    respiration in black soil , different parts of corn and soybean straws were mixed separately with soil , and then incubated for 61 d at 25℃.The microbial biomass carbon (MBC) and nitrogen (MBN), mineral N and soil microbial respiration were measured after incubation , then the relationship between soil microbial biomass (MBC, MBN), respiration and C, N concentrations of different crop residue parts were analyzed .The results showed that the MBC under soybean roots treatments were highest , followed by bottom corn stover , soybean stalk , corn leaves , up corn stover, corn roots, the lowest were under soybean leaves .The MBN of different treatment in a descending order as: bottom corn stover, corn leaves, soybean roots, corn roots, up corn stover, soybean stalk, soybean leaves.Except for soybean leaves , the MBC/MBN of soil amended with residues were lower than blank control significantly .There were significant correlation between the carbon concentration of residues and MBC , MBN, MBC/MBN, microbial respiration rate and microbial metabolic quotient .MBC, mi-crobial respiration rate and microbial metabolic quotient were negative related to the nitrogen concentration of residues .Moreover , a highly significant negative correlation was found between carbon concentration of residues and mineral nitrogen concentration of soil . Soil microbial respiration rate and microbial metabolic quotient among different controls were similar .A significant positive correlation was found between microbial respiration rate and microbial metabolic quotient .Those results suggested that straw amendments promote the growth and reproduction of the microbes with lower C /N, such as bacteria and actinomycetes , residues with higher nitrogen concen-tration lead to lower microbial biomass , respiration and metabolic activity at later stage of incubation , the microbial metabolic activity is a more important factor than the soil microbial biomass in residues decomposition and microbial respiration .

  17. Microbial respiration with chlorine oxyanions: diversity and physiological and biochemical properties of chlorate- and perchlorate-reducing microorganisms.

    Science.gov (United States)

    Liebensteiner, Martin G; Oosterkamp, Margreet J; Stams, Alfons J M

    2016-02-01

    Chlorine oxyanions are valuable electron acceptors for microorganisms. Recent findings have shed light on the natural formation of chlorine oxyanions in the environment. These suggest a permanent introduction of respective compounds on Earth, long before their anthropogenic manufacture. Microorganisms that are able to grow by the reduction of chlorate and perchlorate are affiliated with phylogenetically diverse lineages, spanning from the Proteobacteria to the Firmicutes and archaeal microorganisms. Microbial reduction of chlorine oxyanions can be found in diverse environments and different environmental conditions (temperature, salinities, pH). It commonly involves the enzymes perchlorate reductase (Pcr) or chlorate reductase (Clr) and chlorite dismutase (Cld). Horizontal gene transfer seems to play an important role for the acquisition of functional genes. Novel and efficient Clds were isolated from microorganisms incapable of growing on chlorine oxyanions. Archaea seem to use a periplasmic Nar-type reductase (pNar) for perchlorate reduction and lack a functional Cld. Chlorite is possibly eliminated by alternative (abiotic) reactions. This was already demonstrated for Archaeoglobus fulgidus, which uses reduced sulfur compounds to detoxify chlorite. A broad biochemical diversity of the trait, its environmental dispersal, and the occurrence of relevant enzymes in diverse lineages may indicate early adaptations of life toward chlorine oxyanions on Earth.

  18. Selection rhizosphere-competent microbes for development of microbial products as biocontrol agents

    Science.gov (United States)

    Mashinistova, A. V.; Elchin, A. A.; Gorbunova, N. V.; Muratov, V. S.; Kydralieva, K. A.; Khudaibergenova, B. M.; Shabaev, V. P.; Jorobekova, Sh. J.

    2009-04-01

    Rhizosphere-borne microorganisms reintroduced to the soil-root interface can establish without inducing permanent disturbance in the microbial balance and effectively colonise the rhizosphere due to carbon sources of plant root exudates. A challenge for future development of microbial products for use in agriculture will be selection of rhizosphere-competent microbes that both protect the plant from pathogens and improve crop establishment and persistence. In this study screening, collection, identification and expression of stable and technological microbial strains living in soils and in the rhizosphere of abundant weed - couch-grass Elytrigia repens L. Nevski were conducted. A total of 98 bacteria isolated from the rhizosphere were assessed for biocontrol activity in vitro against phytopathogenic fungi including Fusarium culmorum, Fusarium heterosporum, Fusarium oxysporum, Drechslera teres, Bipolaris sorokiniana, Piricularia oryzae, Botrytis cinerea, Colletothrichum atramentarium and Cladosporium sp., Stagonospora nodorum. Biocontrol activity were performed by the following methods: radial and parallel streaks, "host - pathogen" on the cuts of wheat leaves. A culture collection comprising 64 potential biocontrol agents (BCA) against wheat and barley root diseases has been established. Of these, the most effective were 8 isolates inhibitory to at least 4 out of 5 phytopathogenic fungi tested. The remaining isolates inhibited at least 1 of 5 fungi tested. Growth stimulating activity of proposed rhizobacteria-based preparations was estimated using seedling and vegetative pot techniques. Seeds-inoculation and the tests in laboratory and field conditions were conducted for different agricultural crops - wheat and barley. Intact cells, liquid culture filtrates and crude extracts of the four beneficial bacterial strains isolated from the rhizosphere of weed were studied to stimulate plant growth. As a result, four bacterial strains selected from rhizosphere of weed

  19. respiration and transpiration characteristics of selected fresh fruits ...

    African Journals Online (AJOL)

    AISA

    Key words : packaging, respiration, transpiration, temperature, relative humidity. RESUME ... microbial attack. Shelf life is inversely ... of relative humidity. MATERIALS AND METHODS ..... physiology and crop preservation. (M.) Lieberman ed.

  20. Three-dimensional soil organic matter distribution, accessibility and microbial respiration in macroaggregates using osmium staining and synchrotron X-ray computed tomography

    Science.gov (United States)

    Rawlins, Barry G.; Wragg, Joanna; Reinhard, Christina; Atwood, Robert C.; Houston, Alasdair; Lark, R. Murray; Rudolph, Sebastian

    2016-12-01

    The spatial distribution and accessibility of organic matter (OM) to soil microbes in aggregates - determined by the fine-scale, 3-D distribution of OM, pores and mineral phases - may be an important control on the magnitude of soil heterotrophic respiration (SHR). Attempts to model SHR on fine scales requires data on the transition probabilities between adjacent pore space and soil OM, a measure of microbial accessibility to the latter. We used a combination of osmium staining and synchrotron X-ray computed tomography (CT) to determine the 3-D (voxel) distribution of these three phases (scale 6.6 µm) throughout nine aggregates taken from a single soil core (range of organic carbon (OC) concentrations: 4.2-7.7 %). Prior to the synchrotron analyses we had measured the magnitude of SHR for each aggregate over 24 h under controlled conditions (moisture content and temperature). We test the hypothesis that larger magnitudes of SHR will be observed in aggregates with (i) shorter length scales of OM variation (more aerobic microsites) and (ii) larger transition probabilities between OM and pore voxels. After scaling to their OC concentrations, there was a 6-fold variation in the magnitude of SHR for the nine aggregates. The distribution of pore diameters and tortuosity index values for pore branches was similar for each of the nine aggregates. The Pearson correlation between aggregate surface area (normalized by aggregate volume) and normalized headspace C gas concentration was both positive and reasonably large (r = 0.44), suggesting that the former may be a factor that influences SHR. The overall transition probabilities between OM and pore voxels were between 0.07 and 0.17, smaller than those used in previous simulation studies. We computed the length scales over which OM, pore and mineral phases vary within each aggregate using 3-D indicator variograms. The median range of models fitted to variograms of OM varied between 38 and 175 µm and was generally larger than

  1. Effect of Soil Enzymes on Soil Microbial Respiration in Secondary Forest in Mountainous Region of Eastern Liaoning Province%辽东山区次生林土壤酶对土壤微生物呼吸的影响

    Institute of Scientific and Technical Information of China (English)

    范阿南; 刘峰

    2013-01-01

    Taking soil in three kinds of natural secondary forest (Quercus mongolica ,weed trees & Juglans mand-shurica) as researching objects ,through determination of amylase ,invertase ,dehydrogenase &catalase activity ,the relationship between soil enzyme activities and soil microbial respiration in the mountainous regions of eastern Liaon-ing Province were discussed .Result shows that :soil enzyme activity & soil microbial respiration of Quercus mon-golica ,weed trees & Juglans mandshurica have certain seasonal fluctuations ,but the correlation is not significant . Except biological respiration & catalase activity of Juglans m andshurica has significant relationship ,microbial res-piration & four kinds of activity of Quercus mongolica & weed trees has no significant correlation .The result pro-vides a reference for understanding systematically the soil carbon cycle of plant communities for secondary forest in the mountainous regions of Eastern Liaoning Province .%以蒙古栎(Quercus mongolica)林、杂木林和胡桃楸(Juglans mandshurica)林3种天然次生林土壤为研究对象,通过生长季节内表层土壤(0~30 cm )淀粉酶、蔗糖酶、脱氢酶和过氧化氢酶活性以及土壤微生物呼吸速率的测定,探讨了辽东山区土壤酶活性与土壤微生物呼吸之间的关系。结果表明:辽东山区蒙古栎林、杂木林、胡桃楸林土壤酶活性与土壤微生物呼吸具有一定的季节波动,但相关性不显著。除胡桃楸林微生物呼吸与过氧化氢酶活性之间具有显著关系外,蒙古栎林和杂木林微生物呼吸与4种酶活性之间均无显著相关性。研究结果为进一步系统了解辽东山区次生林植物群落土壤碳循环过程提供了参考。

  2. Thermal adaptation of heterotrophic soil respiration in laboratory microcosms.

    Science.gov (United States)

    Mark A. Bradford; Brian W. Watts; Christian A. Davies

    2010-01-01

    Respiration of heterotrophic microorganisms decomposing soil organic carbon releases carbon dioxide from soils to the atmosphere. In the short term, soil microbial respiration is strongly dependent on temperature. In the long term, the response of heterotrophic soil respiration to temperature is uncertain. However, following established evolutionary tradeoffs, mass-...

  3. Compatible Rhizosphere-Competent Microbial Consortium Adds Value to the Nutritional Quality in Edible Parts of Chickpea.

    Science.gov (United States)

    Yadav, Sudheer K; Singh, Surendra; Singh, Harikesh B; Sarma, Birinchi K

    2017-08-02

    Chickpea is used as a high-energy and protein source in diets of humans and livestock. Moreover, chickpea straw can be used as alternative of forage in ruminant diets. The present study evaluates the effect of beneficial microbial inoculation on enhancing the nutritional values in edible parts of chickpea. Two rhizosphere-competent compatible microbes (Pseudomonas fluorescens OKC and Trichoderma asperellum T42) were selected and applied to seeds either individually or in consortium before sowing. Chickpea seeds treated with the microbes showed enhanced plant growth [88.93% shoot length at 60 days after sowing (DAS)] and biomass accumulation (21.37% at 120 DAS). Notably, the uptake of mineral nutrients, viz., N (90.27, 91.45, and 142.64%), P (14.13, 58.73, and 56.84%), K (20.5, 9.23, and 35.98%), Na (91.98, 101.66, and 36.46%), Ca (16.61, 29.46, and 16%), and organic carbon (28.54, 17.09, and 18.54%), was found in the seed, foliage, and pericarp of the chickpea plants, respectively. Additionally, nutritional quality, viz., total phenolic (59.7, 2.8, and 17.25%), protein (9.78, 18.53, and 7.68%), carbohydrate content (26.22, 30.21, and 26.63%), total flavonoid content (3.11, 9.15, and 7.81%), and reducing power (112.98, 75.42, and 111.75%), was also found in the seed, foliage, and pericarp of the chickpea plants. Most importantly, the microbial-consortium-treated plants showed the maximum increase of nutrient accumulation and enhancement in nutritional quality in all edible parts of chickpea. Nutritional partitioning in different edible parts of chickpea was also evident in the microbial treatments compared to their uninoculated ones. The results thus clearly demonstrated microbe-mediated enhancement in the dietary value of the edible parts of chickpea because seeds are consumed by humans, whereas pericarp and foliage (straw) are used as an alternative of forage and roughage in ruminant diets.

  4. Autotrophic and heterotrophic components of soil respiration in permafrost zone.

    Science.gov (United States)

    Udovenko, Maria; Goncharova, Olga

    2016-04-01

    Soil carbon dioxide emissions production is an important integral indicator of soil biological activity and it includes several components: the root respiration and microbial decomposition of organic matter. Separate determination of the components of soil respiration is necessary for studying the balance of carbon in the soil and to assessment its potential as a sink or source of carbon dioxide. The aim of this study was testing field methods of separate determination of root and microbial respiration in soils of north of West Siberia. The research took place near the town Nadym, Yamalo-Nenets Autonomous District (north of West Siberia).The study area was located in the northern taiga with sporadic permafrost. Investigations were carried out at two sites: in forest and in frozen peatland. 3 methods were tested for the separation of microbial and root respiration. 1) "Shading"; 2) "Clipping"(removing the above-ground green plant parts); 3)a modified method of roots exclusion (It is to compare the emission of soils of "peat spots", devoid of vegetation and roots, and soils located in close proximity to the spots on which there is herbaceous vegetation and moss). For the experiments on methods of "Shading" and "Clipping" in the forest and on the frozen peatland ware established 12 plots, 1 x 1 m (3 plots in the forest and at 9 plots on frozen peatland; 4 of them - control).The criterions for choosing location sites were the similarity of meso- and microrelief, the same depth of permafrost, the same vegetation. Measurement of carbon dioxide emissions (chamber method) was carried out once a day, in the evening, for a week. Separation the root and microbial respiration by "Shading" showed that in the forest the root respiration contribution is 5%, and microbial - 95%. On peatlands root respiration is 41%, 59% of the microbial. In the experiment "Clipping" in peatlands root respiration is 56%, the microbial respiration - 44%, in forest- root respiration is 17%, and

  5. Contribution of Root Respiration to Total Soil Respiration in a Leymus chinensis (Trin.) Tzvel. Grassland of Northeast China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The loss of carbon through root respiration is an important component of grassland carbon budgets. However,few data are available concerning the contribution of root respiration to total soil respiration in grasslands in China. We investigated seasonal variations of soil respiration rate, root biomass, microbial biomass C and organic C content of the soil in a semi-arid Leymus chinensis (Trin.) Tzvel. grassland of northeast China during the 2002 growing season (from May to September). The linear regression relationship between soil respiration rate and root biomass was used to determine the contribution of root respiration to total soil respiration. Soil respiration rate ranged from 2.5 to 11.9 g C/m2 per d with the maximum in late June and minimum in September.The microbial biomass C and organic C content of the soil ranged from 0.3 to 1.5 g C/m2 and from 29 to 34 g C/kg respectively. Root biomass had two peaks, in early June (1.80 kg/m2) and mid-August (1.73 kg/m2). Root respiration rate peaked in mid-August (6.26 g C/m2 per d), whereas microbial respiration rate peaked in late June (7.43 g C/m2 per d). We estimated that the contribution of root respiration to total soil respiration during the growing season ranged from 38% to 76%.

  6. Contribution of root respiration to soil respiration in a C3/C4 mixed grassland

    Indian Academy of Sciences (India)

    Wei Wang; Kenji Ohse; Jianjun Liu; Wenhong Mo; Takehisa Oikawa

    2005-09-01

    The spatial and temporal variations of soil respiration were studied from May 2004 to June 2005 in a C3/C4 mixed grassland of Japan. The linear regression relationship between soil respiration and root biomass was used to determine the contribution of root respiration to soil respiration. The highest soil respiration rate of 11.54 mol m–2 s–1 was found in August 2004 and the lowest soil respiration rate of 4.99 mol m–2 s–1 was found in April 2005. Within-site variation was smaller than seasonal change in soil respiration. Root biomass varied from 0.71 kg m–2 in August 2004 to 1.02 in May 2005. Within-site variation in root biomass was larger than seasonal variation. Root respiration rate was highest in August 2004 (5.7 mol m–2 s–1) and lowest in October 2004 (1.7 mol m–2 s–1). Microbial respiration rate was highest in August 2004 (5.8 mol m–2 s–1) and lowest in April 2005 (2.59 mol m–2 s–1). We estimated that the contribution of root respiration to soil respiration ranged from 31% in October to 51% in August of 2004, and from 45% to 49% from April to June 2005.

  7. Effects of Plant Diversity, Functional Group Composition, and Fertilization on Soil Microbial Properties in Experimental Grassland: e0125678

    National Research Council Canada - National Science Library

    Tanja Strecker; Romain L Barnard; Pascal A Niklaus; Michael Scherer-Lorenzen; Alexandra Weigelt; Stefan Scheu; Nico Eisenhauer

    2015-01-01

    ... in a long-term biodiversity experiment in semi-natural grassland (Jena Experiment). Plant species richness enhanced microbial basal respiration and microbial biomass, but did not significantly affect microbial specific respiration...

  8. 微生物群落对土壤微生物呼吸速率及其温度敏感性的影响%Altered Microbial Communities Change Soil Respiration Rates and Their Temperature Sensitivity

    Institute of Scientific and Technical Information of China (English)

    范分良; 黄平容; 唐勇军; 李兆君; 梁永超

    2012-01-01

    通过灭菌和重新接种不同土壤微生物群落的方法,探索了改变土壤微生物群落对土壤微生物呼吸速率及其温度敏感性的影响.结果表明,灭菌海伦黑土接种未灭菌的哈尔滨黑土、封丘潮土和祁阳红壤后,15℃时土壤CO2的累积释放量分别为684.25、753.97和644.91μg,25℃时土壤CO2的累积释放量分别为963.06、1 015.44和852.31μg,35℃时土壤CO2的累积释放量分别为1 252.55、380.36和1 177.88μg;土壤CO2的累积释放量随接种剂土壤pH增加而增加,而与接种剂土壤有机质含量高低、接种剂土壤与被接种土壤的地理距离无关.15、25和35℃时,接种不同微生物群落的土壤呼吸速率表现差异的持续时间分别为104、277和1 177 h,差异持续时间随培养温度增高而延长.接种未灭菌的哈尔滨黑土、封丘潮土和祁阳红壤后,土壤呼吸温度敏感性指数Q10在0~104 h分别为1.63、1.49和1.80,在0~277 h分别为1.43、1.39和1.46,在0~1 609 h分别为1.35、1.35和1.35;呼吸温度敏感性随接种剂土壤pH降低而增加,随培养时间延长而减小.本研究表明改变土壤微生物群落将影响土壤微生物呼吸速率及其温度敏感性.%Inoculating common sterilized soil with different non-sterilized soils was used to investigate the potentials of altered microbial communities to change rate and temperature sensitivity of soil microbial respiration.Results showed that accumulative CO2 emission of sterilized Hailun black soils inoculated with non-sterilized Harbin black soil,Fengqiu fluvo-aquic soil and Qiyang red soil were 684.25,753.97 and 644.91 μg,respectively,at 15℃;were 963.06,1 015.44 and 852.31 μg,respectively,at 25℃;and were 1 252.55,380.36 and 1 177.88 μg,respectively,at 35℃.The soil accumulative CO2 emissions increased with pH of inoculant soils,but did not relate to organic content of and geographical distance from inoculant soils.Difference of microbial respiration rates

  9. Prokaryotic respiration and production in the open ocean

    NARCIS (Netherlands)

    Reinthaler, Thomas

    2006-01-01

    The aim of this thesis was to advance our knowledge on the dynamics of bacterial production and bacterial respiration in the open ocean and linking microbial activity to the physico-chemical environment. Although the currency in carbon cycling measurements is logically carbon, respiration in water i

  10. Structural and Chemical Modification of Fe-Rich Smectite Associated with Microbial Fe-Respiration By Psychrophilic Bacteria in King George Island, West Antarctica

    Science.gov (United States)

    Jung, J.; Kim, J.; Lim, H. S.; Yoon, H.; Lee, Y. K.; Park, K.; Lee, J.; Kim, J. W.

    2014-12-01

    Surface soil samples were collected from Antarctic exploration (2010/2011, 2011/2012) at Barton Peninsula, King George Island, West Antarctica to determine the feasible biological alteration of clay minerals in Antarctica where the physical weathering is considered to be a major process. Seven areas (1226-1, 1226-2, 0101-4, 0105-1, 0105-2, 0107-2, 0107-3) from the coast toward the inland were investigated. The duration of exposure of soil samples to the air depending on the retraction of ice to the inland may affect the microbial activity resulting in the biogeochemical mineral alteration. The multiline of techniques for example, X-ray diffraction (XRD), Scanning Electron Microscope (SEM), wet chemistry analysis including the extent of Fe(III) reduction, and batch experiments of microbe-mineral interaction under the low temperature that mimics the Antarctic condition to understand the mechanism of biogeochemical alteration of clay minerals. Clay minerals of smectite, mica, chlorite and kaolinite were detected in the XRD profiles. The variation of relative amount of clay minerals in the regions indicated that the physical/biological alteration might be different depending on the duration of ice retraction. From the batch experiment using Nontronite (NAu-1), moreover, we confirm that Psychrophilic bacteria (Shewanella sp. isolated from King George Island) reduce structural Fe(III) of clay mineral, and occur structural change of smectite at low temperature (4℃ and 15℃). The present study, therefore, would present the feasibility of biological effects on chemical modification through the structural changes in clay mineral in cold environment and suggest a new pathway of Fe-supply into the Antarctic Ocean.

  11. Structural and chemical modification of Fe-rich smectite associated with microbial Fe-respiration by psychrophilic bacteria in King George Island, West Antarctica

    Science.gov (United States)

    Jung, J.; Kim, J. Y.; Lim, H. S.; Lee, Y. K.; Kim, O. S.; Park, K.; Lee, J.; Yoon, H.; Kim, J. W.

    2015-12-01

    Biotic/abiotic redox reaction is a ubiquitous process in a mineral alteration and an elemental cycling in the sediments/ocean. The role of psychrophiles in clay mineral alteration was tested in the soil for the seven sites from the coast to the inland at Barton Peninsula. Batch experiments of microbe-mineral interaction under the various temperatures (4 ℃, 15 ℃) that mimics the Antarctic condition were performed to understand the mechanism of biogeochemical alteration of clay minerals. After 12 months incubation of the bulk surface soil samples in the M1 minimal medium, the extent of Fe reduction was reached up to 49 and 42 % at 4 ℃ and 15 ℃. The increase in CEC corresponds to the extent of Fe reduction. Moreover, precipitations of secondary phase mineral such as vivianite were observed only in 12 months enrichment samples at 4 ℃ and 15 ℃. Sulfate reducing bacteria and Fe-reducing bacteria capable of reducing Fe were identified by 16S rRNA pyrosequencing. The Fe reduction coupled to oxidation of organic matter might be enhanced by cooperation of a consortium of Sulfate reducing bacteria and Fe-reducing bacteria. Moreover, Nitrate reducing bacteria which have an ability to oxidize ferrous iron anaerobically with nitrate reduction were identified at 15 ℃. The lower values observed in the extent of Fe reduction at 15 ℃ may be associated with Fe-oxidation induced by nitrate reduction.In order to verify the mechanism of microbial Fe reduction in clay minerals at low temperatures (4 and 15 ℃), Fe-rich Nontronite (NAu-1) and Psychrophilic bacteria were incubated for 4 months in anaerobic condition. Total structural Fe in NAu-1 is 16.4 % and 99.6 % of the total Fe is ferric. The extent of Fe reduction in nontronite was reached up to 11.5 % and 11 % at 4 ℃ and 15 ℃, respectively. The structural modification of biologically Fe-reduced nontronite was observed in the (001) peak shift to the lower 2 theta indicating the layer collapse associated with K

  12. Impact of human activities on soil respiration:A review

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Soil respiration is one of the primary fluxes of carbon between soils and the atmosphere.It is produced by rhizosphere respiration and soil microbial respiration.Soil respiration is not only affected by environmental factors,but also changes with the hu-man-induced disturbances of ecosystems.Land-use,the measures of land management,the pollution of soil,and so on can affect soil respiration and change the soil efflux.According to some research,the authors summed up their impacts on soil respiration by human activities through land-use changes and land-management measures among agroecosystem,grassland ecosystem,and for-est ecosystem.The results showed that (1) when adding fertilization to farmland,the soil respiration will increase;(2) fenced land can decrease soil respiration,while soil respiration in the grazed land at a grassland ecosystem will decline with the increasing of grazing intensity;(3) with grassland fertilization;farmland cultivation;fire,fertilization,and cutting of forest,conflicting results were found in the changes of soil respiration.Perhaps plant species,site condition,and measurement season can lead to different results on soil respiration.

  13. Can soil respiration estimate neglect the contribution of abiotic exchange?

    Institute of Scientific and Technical Information of China (English)

    Xi CHEN; WenFeng WANG; GePing LUO; Hui YE

    2014-01-01

    This study examines the hypothesis that soil respiration can always be interpreted purely in terms of biotic processes, neglecting the contribution of abiotic exchange to CO2 fluxes in alkaline soils of arid areas that characterize 5%of the Earth’s total land surface. Analyses on flux data collected from previous studies suggested reconciling soil respiration as organic (root/microbial respiration) and inorganic (abiotic CO2 exchange) respiration, whose contributions in the total CO2 flux were determined by soil alkaline content. On the basis of utilizing mete-orological and soil data collected from the Xinjiang and Central Asia Scientific Data Sharing Platform, an incorpo-rated model indicated that inorganic respiration represents almost half of the total CO2 flux. Neglecting the abiotic module may result in overestimates of soil respiration in arid alkaline lands, which partly explains the long-sought“missing carbon sink”.

  14. Root Zone Respiration on Hydroponically Grown Wheat Plant Systems

    Science.gov (United States)

    Soler-Crespo, R. A.; Monje, O. A.

    2010-01-01

    Root respiration is a biological phenomenon that controls plant growth and physiological development during a plant's lifespan. This process is dependent on the availability of oxygen in the system where the plant is located. In hydroponic systems, where plants are submerged in a solution containing vital nutrients but no type of soil, the availability of oxygen arises from the dissolved oxygen concentration in the solution. This oxygen concentration is dependent on the , gas-liquid interface formed on the upper surface of the liquid, as given by Henry's Law, depending on pressure and temperature conditions. Respiration rates of the plants rise as biomass and root zone increase with age. The respiration rate of Apogee wheat plants (Triticum aestivum) was measured as a function of light intensity (catalytic for photosynthesis) and CO2 concentration to determine their effect on respiration rates. To determine their effects on respiration rate and plant growth microbial communities were introduced into the system, by Innoculum. Surfactants were introduced, simulating gray-water usage in space, as another factor to determine their effect on chemical oxygen demand of microbials and on respiration rates of the plants. It is expected to see small effects from changes in CO2 concentration or light levels, and to see root respiration decrease in an exponential manner with plant age and microbial activity.

  15. Chronic impact of sulfamethoxazole on acetate utilization kinetics and population dynamics of fast growing microbial culture.

    Science.gov (United States)

    Kor-Bicakci, G; Pala-Ozkok, I; Rehman, A; Jonas, D; Ubay-Cokgor, E; Orhon, D

    2014-08-01

    The study evaluated the chronic impact of sulfamethoxazole on metabolic activities of fast growing microbial culture. It focused on changes induced on utilization kinetics of acetate and composition of the microbial community. The experiments involved a fill and draw reactor, fed with acetate and continuous sulfamethoxazole dosing of 50 mg/L. The evaluation relied on model evaluation of the oxygen uptake rate profiles, with parallel assessment of microbial community structure by 454-pyrosequencing. Continuous sulfamethoxazole dosing inflicted a retardation effect on acetate utilization in a way commonly interpreted as competitive inhibition, blocked substrate storage and accelerated endogenous respiration. A fraction of acetate was utilized at a much lower rate with partial biodegradation of sulfamethoxazole. Results of pyrosequencing with a replacement mechanism within a richer more diversified microbial culture, through inactivation of vulnerable fractions in favor of species resistant to antibiotic, which made them capable of surviving and competing even with a slower metabolic response. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Synchronization of respiration

    NARCIS (Netherlands)

    Garssen, B.

    In order to study synchronization of respiration, three different videofragments were presented to 21 normal subjects. Each fragment showed a ‘therapeutic interview’ specially performed for this purpose, with a ‘patient’ breathing in a particular way. The respiration of model 1 was deep, slow and

  17. [Effects of nitrogen fertilization on soil respiration during maize growth season].

    Science.gov (United States)

    Li, Jian-Min; Ding, Wei-Xin; Cai, Zu-Cong

    2010-08-01

    In order to understand how nitrogen (N) fertilization affects soil respiration, a pot experiment with splitting-root compartment and by root-cutting was conducted in a greenhouse. The experiment had four treatments, i. e., unplanted and N-unfertilized (CKO), unplanted but fertilized with 150 mg N x kg(-1) CKN), planted maize (Zea mays L.) but N-unfertilized (MO), and planted maize and fertilized with 150 mg N x kg(-1) (MN). Soil respiration, soil basal respiration, root respiration, and rhizospheric microbial respiration were measured simultaneously. In unplanted soils (treatments CKO and CKN), soil respiration rate (soil basal respiration) ranged from 13.41 to 77.27 mg C x m(-2) x h(-1), and N fertilization had less effect; while in planted soils, the averaged soil respiration rate in treatment MN amounted to 138.54 mg C x m(-2) x h(-1), and was 17.7% higher (P < 0.05) than that in treatment MO. This increment mainly occurred at tasselling and flowering stages. During maize growth season, the contribution of soil basal respiration, root respiration, and rhizospheric microbial respiration to soil respiration in treatments MN and MO was 36.2%, 45.9%, and 17.9%, and 35.5%, 36.9%, and 37.6%, respectively.

  18. Respirator Fact Sheet

    Science.gov (United States)

    ... have expiration dates that should be checked before purchase. Also, over time your mask can get old ... Respirator Fact Sheet [PDF - 706 KB] Follow NIOSH Facebook Flickr Pinterest Twitter YouTube NIOSH Homepage NIOSH A- ...

  19. Respiration in Aquatic Insects.

    Science.gov (United States)

    MacFarland, John

    1985-01-01

    This article: (1) explains the respiratory patterns of several freshwater insects; (2) describes the differences and mechanisms of spiracular cutaneous, and gill respiration; and (3) discusses behavioral aspects of selected aquatic insects. (ML)

  20. Responses of switchgrass soil respiration and its components to precipitation gradient in a mescocosm study

    Science.gov (United States)

    The objectives of this study were to investigate the effects of the precipitation changes on soil, microbial and root respirations of switchgrass soils, and the relationships between soil respiration and plant growth, soil moisture and temperature. A mesocosm experiment was conducted with five prec...

  1. Competence is Competence

    DEFF Research Database (Denmark)

    Bramming, Pia

    2004-01-01

    The article will address competence, its' diffusion, application, and the consequence of this application within the field of Human Resource Management (HRM). The concept competence-in-practice will be presented and in conclusion the article will consider implications and possibilities of compete...

  2. Cattle respiration facility

    DEFF Research Database (Denmark)

    Hellwing, Anne Louise Frydendahl; Lund, Peter; Weisbjerg, Martin Riis

    2012-01-01

    In Denmark, the emission rate of methane from dairy cows has been calculated using the IPCC standard values for dairy cows in Western countries, due to the lack of national data. Therefore, four respiration chambers for dairy cows were built with the main purpose of measuring methane, but also...

  3. Riparian land-use and rehabilitation: impact on organic matter input and soil respiration.

    Science.gov (United States)

    Oelbermann, Maren; Raimbault, Beverly A; Gordon, A M

    2015-02-01

    Rehabilitated riparian zones in agricultural landscapes enhance environmental integrity and provide environmental services such as carbon (C) sequestration. This study quantified differences in organic matter input, soil biochemical characteristics, and soil respiration in a 25-year-old rehabilitated (RH), grass (GRS), and undisturbed natural forest (UNF) riparian zone. Input from herbaceous vegetation was significantly greater (P Soil bulk density was significantly greater (P soil chemical characteristics were significantly lower. Soil respiration rates were lowest (P Soil respiration rates were significantly different (P soil moisture (P soil temperature (P Soil potential microbial activity indicated a significantly different (P soil organic C and lower soil respiration rates.

  4. Heterotrophic components of soil respiration in pastures and forests in southwestern Amazonia, Acre, Brazil

    Directory of Open Access Journals (Sweden)

    Eric Atlas Davidson

    2008-12-01

    Full Text Available In this paper we present data on soil microbial biomass and heterotrophic respiration in pastures, mature and secondary forests, in order to elucidate their contribution to total CO2 flux from soil to atmosphere. The research was conducted in Southwestern Amazonia, Acre State, Brazil. Microbial biomass was estimated using a variation of the traditional fumigation-extraction method and heterotrophic respiration was measured using respirometry flasks attached to an infrared gas analyzer. Soil microbial biomass and heterotrophic respiration did not differ statistically among pastures, mature and secondary forests. These laboratory results indicate that higher CO2 fluxes from pasture soils measured in situ are probably due to higher root respiration by pasture grasses.

  5. Pore-scale investigation on the response of heterotrophic respiration to moisture conditions in heterogeneous soils

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Zhifeng; Liu, Chongxuan; Todd-Brown, Katherine E.; Liu, Yuanyuan; Bond-Lamberty, Ben; Bailey, Vanessa L.

    2016-11-15

    The relationship between microbial respiration rate and soil moisture content is an important property for understanding and predicting soil organic carbon degradation, CO2 production and emission, and their subsequent effects on climate change. This paper reports a pore-scale modeling study to investigate the response of heterotrophic respiration to moisture conditions in soils and to evaluate various factors that affect this response. X-ray computed tomography was used to derive soil pore structures, which were then used for pore-scale model investigation. The pore-scale results were then averaged to calculate the effective respiration rates as a function of water content in soils. The calculated effective respiration rate first increases and then decreases with increasing soil water content, showing a maximum respiration rate at water saturation degree of 0.75 that is consistent with field and laboratory observations. The relationship between the respiration rate and moisture content is affected by various factors, including pore-scale organic carbon bioavailability, the rate of oxygen delivery, soil pore structure and physical heterogeneity, soil clay content, and microbial drought resistivity. Simulations also illustrates that a larger fraction of CO2 produced from microbial respiration can be accumulated inside soil cores under higher saturation conditions, implying that CO2 flux measured on the top of soil cores may underestimate or overestimate true soil respiration rates under dynamic moisture conditions. Overall, this study provides mechanistic insights into the soil respiration response to the change in moisture conditions, and reveals a complex relationship between heterotrophic microbial respiration rate and moisture content in soils that is affected by various hydrological, geochemical, and biophysical factors.

  6. Soil Type Dependent Rhizosphere Competence and Biocontrol of Two Bacterial Inoculant Strains and Their Effects on the Rhizosphere Microbial Community of Field-Grown Lettuce: e103726

    National Research Council Canada - National Science Library

    Susanne Schreiter; Martin Sandmann; Kornelia Smalla; Rita Grosch

    2014-01-01

    .... The present study is aimed to unravel the effects of soil types on the rhizosphere competence and biocontrol activity of the two inoculant strains Pseudomonas jessenii RU47 and Serratia plymuthica...

  7. Soil type dependent rhizosphere competence and biocontrol of two bacterial inoculant strains and their effects on the rhizosphere microbial community of field-grown lettuce

    National Research Council Canada - National Science Library

    Schreiter, Susanne; Sandmann, Martin; Smalla, Kornelia; Grosch, Rita

    2014-01-01

    .... The present study is aimed to unravel the effects of soil types on the rhizosphere competence and biocontrol activity of the two inoculant strains Pseudomonas jessenii RU47 and Serratia plymuthica...

  8. Bacterial respiration of arsenic and selenium

    Science.gov (United States)

    Stolz, J.F.; Oremland, R.S.

    1999-01-01

    Oxyanions of arsenic and selenium can be used in microbial anaerobic respiration as terminal electron acceptors. The detection of arsenate and selenate respiring bacteria in numerous pristine and contaminated environments and their rapid appearance in enrichment culture suggest that they are widespread and metabolically active in nature. Although the bacterial species that have been isolated and characterized are still few in number, they are scattered throughout the bacterial domain and include Gram- positive bacteria, beta, gamma and epsilon Proteobacteria and the sole member of a deeply branching lineage of the bacteria, Chrysiogenes arsenatus. The oxidation of a number of organic substrates (i.e. acetate, lactate, pyruvate, glycerol, ethanol) or hydrogen can be coupled to the reduction of arsenate and selenate, but the actual donor used varies from species to species. Both periplasmic and membrane-associated arsenate and selenate reductases have been characterized. Although the number of subunits and molecular masses differs, they all contain molybdenum. The extent of the environmental impact on the transformation and mobilization of arsenic and selenium by microbial dissimilatory processes is only now being fully appreciated.

  9. Secondary mineral formation associated with respiration of nontronite, NAu-1 by iron reducing bacteria

    Directory of Open Access Journals (Sweden)

    Furukawa Yoko

    2005-10-01

    Full Text Available Experimental batch and miscible-flow cultures were studied in order to determine the mechanistic pathways of microbial Fe(III respiration in ferruginous smectite clay, NAu-1. The primary purpose was to resolve if alteration of smectite and release of Fe precedes microbial respiration. Alteration of NAu-1, represented by the morphological and mineralogical changes, occurred regardless of the extent of microbial Fe(III reduction in all of our experimental systems, including those that contained heat-killed bacteria and those in which O2, rather than Fe(III, was the primary terminal electron acceptor. The solid alteration products observed under transmission electron microscopy included poorly crystalline smectite with diffuse electron diffraction signals, discrete grains of Fe-free amorphous aluminosilicate with increased Al/Si ratio, Fe-rich grains, and amorphous Si globules in the immediate vicinity of bacterial cells and extracellular polymeric substances. In reducing systems, Fe was also found as siderite. The small amount of Fe partitioned to the aqueous phase was primarily in the form of dissolved Fe(III species even in the systems in which Fe(III was the primary terminal electron acceptor for microbial respiration. From these observations, we conclude that microbial respiration of Fe(III in our laboratory systems proceeded through the following: (1 alteration of NAu-1 and concurrent release of Fe(III from the octahedral sheets of NAu-1; and (2 subsequent microbial respiration of Fe(III.

  10. Moisture Limitations Dominate the Seasonality of Heterotrophic Respiration in the Southern Hemisphere

    Science.gov (United States)

    Konings, A. G.; Bloom, A. A.; Liu, J.; Parazoo, N.; Schimel, D.; Bowman, K. W.

    2016-12-01

    Heterotrophic respiration is the dominant process causing the loss of soil organic carbon, the largest stock of carbon on earth. Temperature, soil moisture, substrate availability, and soil microbial composition can all affect the rate of heterotrophic respiration. Without isotopic or root-specific measurements, it can be difficult to separate the total soil respiration into autotrophic and heterotrophic respiration. As a result, the large-scale variability and seasonality of heterotrophic respiration remains unknown, especially outside the mid-latitudes. In this study, we use remote-sensing based observational constraints to estimate heterotrophic respiration at large scales. We combine net ecosystem exchange estimates from atmospheric inversions of the Carbon Monitoring System-Flux project (CMS-Flux) with a recently derived optimally-scaled GPP dataset based on satellite-observed solar-induced fluorescence variations to estimate total ecosystem respiration. The ecosystem respiration is then separated into autotrophic and heterotrophic components based on a spatially-varying carbon use efficiency retrieved in a model-data fusion framework (CARDAMOM). The three datasets are combined into a Bayesian framework to derive the uncertainty distribution of global heterotrophic respiration allowing only physically realistic solutions (appropriate signs for all fluxes), In most Southern Hemisphere regions where precipitation and temperature are anti-correlated (e.g. dry African woodlands, Sahel, Southern India, etc..), the seasonality of heterotrophic respiration follows precipitation, not temperature. This results in an apparent anti-correlation between heterotrophic respiration and temperature. By comparison, a data-constrained terrestrial ecosystem model that does not simulate an effect of soil moisture on heterotrophic respiration did not show this anti-correlation. Data-driven heterotrophic respiration estimates such as those presented here may be used to benchmark

  11. Soil Drying Effects on the Carbon Isotope Composition of Soil Respiration

    Science.gov (United States)

    Phillips, C. L.; Nickerson, N.; Risk, D.; Kayler, Z. E.; Rugh, W.; Mix, A. C.; Bond, B. J.

    2008-12-01

    Stable isotopes are used widely as a tool for determining sources of carbon (C) fluxes in ecosystem C studies. Environmental factors that change over time, such as moisture, can create dynamic changes in the isotopic composition of C assimilated by plants, and offers a unique opportunity to distinguish fast- responding plant C from slower-responding soil C pools, which under steady-state conditions may be too similar isotopically to partition. Monitoring the isotopic composition of soil respiration over a period of changing moisture conditions is potentially a useful approach for characterizing plant contributions to soil respiration. But this partitioning hinges on the assumption that any change in the isotopic signature of soil respiration is solely due to recent photosynthetic discrimination, and that post-photosynthetic processes, such as microbial respiration, do not discriminate as moisture decreases. The purpose of the present study is to test the assumption that δ13CO2 from microbial respiration remains static as soil dries. We conducted a series of greenhouse experiments employing different techniques to isolate microbial respiration from root respiration. The first involves removing roots from soil, and showed that when roots are present, respiration from dry soil is enriched in 13C relative to moist soil, but when roots are absent, respiration is isotopically similar from moist and dry soils. This indicates that rhizospheric respiration changes isotopically with moisture whereas soil microbial respiration does not. In contrast, a second experiment in which soil columns without plants were monitored as they dried, showed respiration from very dry soil to be enriched by 8‰ relative to moist soil. However, simulations with an isotopologue-based soil gas diffusion model demonstrate that at least a portion of the apparent enrichment is due to non-steady state gas transport processes. Careful sampling methodologies which prevent or account for non

  12. REGULATORY MECHANISMS OF CELLULAR RESPIRATION

    Science.gov (United States)

    Barron, E. S. Guzman; Nelson, Leonard; Ardao, Maria Isabel

    1948-01-01

    Oxidizing agents of sulfhydryl groups such as iodosobenzoate, alkylating agents such as iodoacetamide, and mercaptide-forming agents such as cadmium chloride, mercuric chloride, p-chloromercuribenzoate, sodium arsenite, and p-carboxyphenylarsine oxide, added in small concentrations to a suspension of sea urchin sperm produced an increase in respiration. When the concentration was increased there was an inhibition. These effects are explained by postulating the presence in the cells of two kinds of sulfhydryl groups: soluble sulfhydryl groups, which regulate cellular respiration, and fixed sulfhydryl groups, present in the protein moiety of enzymes. Small concentrations of sulfhydryl reagents combine only with the first, thus producing an increase in respiration; when the concentration is increased, the fixed sulfhydryl groups are also attacked and inhibition of respiration is the consequence. Other inhibitors of cell respiration, such as cyanide and urethanes, which do not combine with —SH groups, did not stimulate respiration in small concentration. PMID:18891144

  13. Contributions of ectomycorrhizal fungal mats to forest soil respiration

    Directory of Open Access Journals (Sweden)

    C. L. Phillips

    2012-02-01

    Full Text Available Distinct aggregations of fungal hyphae and rhizomorphs, or "mats" formed by some genera of ectomycorrhizal (EcM fungi are common features of soils in coniferous forests of the Pacific Northwest. We measured in situ respiration rates of Piloderma mats and neighboring non-mat soils in an old-growth Douglas-fir forest in Western Oregon to investigate whether there was an incremental increase in respiration from mat soils, and to estimate mat contributions to total soil respiration. We found that areas where Piloderma mats colonized the organic horizon often had higher soil surface flux than non-mats, with the incremental increase in respiration averaging 16 % across two growing seasons. Both soil physical factors and biochemistry were related to the higher surface flux of mat soils. When air-filled pore space was low (high soil moisture, soil CO2 production was concentrated into near-surface soil horizons where mats tend to colonize, resulting in greater apparent differences in respiration between mat and non-mat soils. Respiration rates were also correlated with the activity of chitin-degrading soil enzymes. This suggests that the elevated activity of fungal mats may be related to consumption or turnover of chitinous fungal cell-wall materials. We found Piloderma mats present across 57 % of the soil surface in the study area, and use this value to estimate a respiratory contribution from mats at the stand-scale of about 9 % of total soil respiration. The activity of EcM mats, which includes both EcM fungi and microbial associates, was estimated to constitute a substantial portion of total soil respiration in this old-growth Douglas-fir forest.

  14. Respiration in ocean margin sediments

    OpenAIRE

    Andersson, J.H.

    2007-01-01

    The aim of this thesis was the study of respiration in ocean margin sediments and the assessments of tools needed for this purpose. The first study was on the biological pump and global respiration patterns in the deep ocean using an empirical model based on sediment oxygen consumption data. In this thesis the depth dependence of respiration patterns was modelled using a compiled data set of sediment oxygen consumption rates. We showed that the depth relationship can best be described by a do...

  15. Microbial metabolism in soil at low temperatures: Mechanisms unraveled by position-specific 13C labeling

    Science.gov (United States)

    Bore, Ezekiel

    2016-04-01

    Microbial transformation of organic substances in soil is the most important process of the C cycle. Most of the current studies base their information about transformation of organic substances on incubation studies under laboratory conditions and thus, we have a profound knowledge on SOM transformations at ambient temperatures. However, metabolic pathway activities at low temperature are not well understood, despite the fact that the processes are relevant for many soils globally and seasonally. To analyze microbial metabolism at low soil temperatures, isotopomeres of position-specifically 13C labeled glucose were incubated at three temperature; 5, -5 -20 oC. Soils were sampled after 1, 3 and 10 days and additionally after 30 days for samples at -20 °C. The 13C from individual molecule position was quantifed in respired CO2, bulk soil, extractable organic C and extractable microbial biomass by chloroform fumigation extraction (CFE) and cell membranes of microbial communities classified by 13C phospholipid fatty acid (PLFA) analysis. 13CO2 released showed a dominance of the flux from C-1 position at 5 °C. Consequently, at 5 °C, pentose phosphate pathway activity is a dominant metabolic pathway of glucose metabolization. In contrast to -5 °C and -20 oC, metabolic behaviors completely switched towards a preferential respiration of the glucose C-4 position. With decreasing temperature, microorganism strongly shifted towards metabolization of glucose via glycolysis which indicates a switch to cellular maintenance. High recoveries of 13C in extractable microbial biomass at -5 °C indicates optimal growth condition for the microorganisms. PLFA analysis showed high incorporation of 13C into Gram negative bacteria at 5 °C but decreased with temperature. Gram positive bacteria out-competed Gram negatives with decreasing temperature. This study revealed a remarkable microbial activity at temperatures below 0 °C, differing significantly from that at ambient

  16. Soil type dependent rhizosphere competence and biocontrol of two bacterial inoculant strains and their effects on the rhizosphere microbial community of field-grown lettuce.

    Directory of Open Access Journals (Sweden)

    Susanne Schreiter

    Full Text Available Rhizosphere competence of bacterial inoculants is assumed to be important for successful biocontrol. Knowledge of factors influencing rhizosphere competence under field conditions is largely lacking. The present study is aimed to unravel the effects of soil types on the rhizosphere competence and biocontrol activity of the two inoculant strains Pseudomonas jessenii RU47 and Serratia plymuthica 3Re4-18 in field-grown lettuce in soils inoculated with Rhizoctonia solani AG1-IB or not. Two independent experiments were carried out in 2011 on an experimental plot system with three soil types sharing the same cropping history and weather conditions for more than 10 years. Rifampicin resistant mutants of the inoculants were used to evaluate their colonization in the rhizosphere of lettuce. The rhizosphere bacterial community structure was analyzed by denaturing gradient gel electrophoresis of 16S rRNA gene fragments amplified from total community DNA to get insights into the effects of the inoculants and R. solani on the indigenous rhizosphere bacterial communities. Both inoculants showed a good colonization ability of the rhizosphere of lettuce with more than 10(6 colony forming units per g root dry mass two weeks after planting. An effect of the soil type on rhizosphere competence was observed for 3Re4-18 but not for RU47. In both experiments a comparable rhizosphere competence was observed and in the presence of the inoculants disease symptoms were either significantly reduced, or at least a non-significant trend was shown. Disease severity was highest in diluvial sand followed by alluvial loam and loess loam suggesting that the soil types differed in their conduciveness for bottom rot disease. Compared to effect of the soil type of the rhizosphere bacterial communities, the effects of the pathogen and the inoculants were less pronounced. The soil types had a surprisingly low influence on rhizosphere competence and biocontrol activity while they

  17. Species identities, not functional groups, explain the effects of earthworms on litter carbon-derived soil respiration

    Science.gov (United States)

    Soil respiration is frequently measured as a surrogate for biological activities and is important in soil carbon cycling. The heterotrophic component of soil respiration is primarily driven by microbial decomposition of leaf litter and soil organic matter, and is partially controlled by resource ava...

  18. Teaching Cellular Respiration & Alternate Energy Sources with a Laboratory Exercise Developed by a Scientist-Teacher Partnership

    Science.gov (United States)

    Briggs, Brandon; Mitton, Teri; Smith, Rosemary; Magnuson, Timothy

    2009-01-01

    Microbial fuel cells are a current research area that harvests electricity from bacteria capable of anaerobic respiration. Graphite is an electrically conductive material that bacteria can respire on, thus it can be used to capture electrons from bacteria. When bacteria transfer electrons to graphite, an electrical potential is created that can…

  19. Teaching Cellular Respiration & Alternate Energy Sources with a Laboratory Exercise Developed by a Scientist-Teacher Partnership

    Science.gov (United States)

    Briggs, Brandon; Mitton, Teri; Smith, Rosemary; Magnuson, Timothy

    2009-01-01

    Microbial fuel cells are a current research area that harvests electricity from bacteria capable of anaerobic respiration. Graphite is an electrically conductive material that bacteria can respire on, thus it can be used to capture electrons from bacteria. When bacteria transfer electrons to graphite, an electrical potential is created that can…

  20. Forest thinning and soil respiration in a ponderosa pine plantation in the Sierra Nevada.

    Science.gov (United States)

    Tang, Jianwu; Qi, Ye; Xu, Ming; Misson, Laurent; Goldstein, Allen H

    2005-01-01

    Soil respiration is controlled by soil temperature, soil water, fine roots, microbial activity, and soil physical and chemical properties. Forest thinning changes soil temperature, soil water content, and root density and activity, and thus changes soil respiration. We measured soil respiration monthly and soil temperature and volumetric soil water continuously in a young ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) plantation in the Sierra Nevada Mountains in California from June 1998 to May 2000 (before a thinning that removed 30% of the biomass), and from May to December 2001 (after thinning). Thinning increased the spatial homogeneity of soil temperature and respiration. We conducted a multivariate analysis with two independent variables of soil temperature and water and a categorical variable representing the thinning event to simulate soil respiration and assess the effect of thinning. Thinning did not change the sensitivity of soil respiration to temperature or to water, but decreased total soil respiration by 13% at a given temperature and water content. This decrease in soil respiration was likely associated with the decrease in root density after thinning. With a model driven by continuous soil temperature and water time series, we estimated that total soil respiration was 948, 949 and 831 g C m(-2) year(-1) in the years 1999, 2000 and 2001, respectively. Although thinning reduced soil respiration at a given temperature and water content, because of natural climate variability and the thinning effect on soil temperature and water, actual cumulative soil respiration showed no clear trend following thinning. We conclude that the effect of forest thinning on soil respiration is the combined result of a decrease in root respiration, an increase in soil organic matter, and changes in soil temperature and water due to both thinning and interannual climate variability.

  1. Soil warming increases metabolic quotients of soil microorganisms without changes in temperature sensitivity of soil respiration

    Science.gov (United States)

    Marañón-Jiménez, Sara; Soong, Jenniffer L.; Leblans, Niki I. W.; Sigurdsson, Bjarni D.; Dauwe, Steven; Fransen, Erik; Janssens, Ivan A.

    2017-04-01

    Increasing temperatures can accelerate soil organic matter (SOM) decomposition and release large amounts of CO2 to the atmosphere, potentially inducing climate change feedbacks. Alterations to the temperature sensitivity and metabolic pathways of soil microorganisms in response to soil warming can play a key role in these soil carbon (C) losses. Here, we present results of an incubation experiment using soils from a geothermal gradient in Iceland that have been subjected to different intensities of soil warming (+0, +1, +3, +5, +10 and +20 °C above ambient) over seven years. We hypothesized that 7 years of soil warming would led to a depletion of labile organic substrates, with a subsequent decrease of the "apparent" temperature sensitivity of soil respiration. Associated to this C limitation and more sub-optimal conditions for microbial growth, we also hypothesized increased microbial metabolic quotients (soil respiration per unit of microbial biomass), which is associated with increases in the relative amount of C invested into catabolic pathways along the warming gradient. Soil respiration and basal respiration rates decreased with soil warming intensity, in parallel with a decline in soil C availability. Contrasting to our first hypothesis, we did not detect changes in the temperature sensitivity of soil respiration with soil warming or on the availability of nutrients and of labile C substrates at the time of incubation. However, in agreement to our second hypothesis, microbial metabolic quotients (soil respiration per unit of microbial biomass) increased at warmer temperatures, while the C retained in biomass decreased as substrate became limiting. Long-term (7 years) temperature increases thus triggered a change in the metabolic functioning of the soil microbial communities towards increasing energy costs for maintenance or resource acquisition, thereby lowering the capacity of C retention and stabilization of warmed soils. These results highlight the need

  2. Biotechnological Aspects of Microbial Extracellular Electron Transfer

    Science.gov (United States)

    Kato, Souichiro

    2015-01-01

    Extracellular electron transfer (EET) is a type of microbial respiration that enables electron transfer between microbial cells and extracellular solid materials, including naturally-occurring metal compounds and artificial electrodes. Microorganisms harboring EET abilities have received considerable attention for their various biotechnological applications, in addition to their contribution to global energy and material cycles. In this review, current knowledge on microbial EET and its application to diverse biotechnologies, including the bioremediation of toxic metals, recovery of useful metals, biocorrosion, and microbial electrochemical systems (microbial fuel cells and microbial electrosynthesis), were introduced. Two potential biotechnologies based on microbial EET, namely the electrochemical control of microbial metabolism and electrochemical stimulation of microbial symbiotic reactions (electric syntrophy), were also discussed. PMID:26004795

  3. Inter-specific competition, but not different soil microbial communities, affects N chemical forms uptake by competing graminoids of upland grasslands.

    Science.gov (United States)

    Medina-Roldán, Eduardo; Bardgett, Richard D

    2012-01-01

    Evidence that plants differ in their ability to take up both organic (ON) and inorganic (IN) forms of nitrogen (N) has increased ecologists' interest on resource-based plant competition. However, whether plant uptake of IN and ON responds to differences in soil microbial community composition and/or functioning has not yet been explored, despite soil microbes playing a key role in N cycling. Here, we report results from a competition experiment testing the hypothesis that soil microbial communities differing in metabolic activity as a result of long-term differences to grazing exposure could modify N uptake of Eriophorum vaginatum L. and Nardus stricta L. These graminoids co-occur on nutrient-poor, mountain grasslands where E. vaginatum decreases and N. stricta increases in response to long-term grazing. We inoculated sterilised soil with soil microbial communities from continuously grazed and ungrazed grasslands and planted soils with both E. vaginatum and N. stricta, and then tracked uptake of isotopically labelled NH(4) (+) (IN) and glycine (ON) into plant tissues. The metabolically different microbial communities had no effect on N uptake by either of the graminoids, which might suggest functional equivalence of soil microbes in their impacts on plant N uptake. Consistent with its dominance in soils with greater concentrations of ON relative to IN in the soluble N pool, Eriophorum vaginatum took up more glycine than N. stricta. Nardus stricta reduced the glycine proportion taken up by E. vaginatum, thus increasing niche overlap in N usage between these species. Local abundances of these species in mountain grasslands are principally controlled by grazing and soil moisture, although our results suggest that changes in the relative availability of ON to IN can also play a role. Our results also suggest that coexistence of these species in mountain grasslands is likely based on non-equilibrium mechanisms such as disturbance and/or soil heterogeneity.

  4. Inter-specific competition, but not different soil microbial communities, affects N chemical forms uptake by competing graminoids of upland grasslands.

    Directory of Open Access Journals (Sweden)

    Eduardo Medina-Roldán

    Full Text Available Evidence that plants differ in their ability to take up both organic (ON and inorganic (IN forms of nitrogen (N has increased ecologists' interest on resource-based plant competition. However, whether plant uptake of IN and ON responds to differences in soil microbial community composition and/or functioning has not yet been explored, despite soil microbes playing a key role in N cycling. Here, we report results from a competition experiment testing the hypothesis that soil microbial communities differing in metabolic activity as a result of long-term differences to grazing exposure could modify N uptake of Eriophorum vaginatum L. and Nardus stricta L. These graminoids co-occur on nutrient-poor, mountain grasslands where E. vaginatum decreases and N. stricta increases in response to long-term grazing. We inoculated sterilised soil with soil microbial communities from continuously grazed and ungrazed grasslands and planted soils with both E. vaginatum and N. stricta, and then tracked uptake of isotopically labelled NH(4 (+ (IN and glycine (ON into plant tissues. The metabolically different microbial communities had no effect on N uptake by either of the graminoids, which might suggest functional equivalence of soil microbes in their impacts on plant N uptake. Consistent with its dominance in soils with greater concentrations of ON relative to IN in the soluble N pool, Eriophorum vaginatum took up more glycine than N. stricta. Nardus stricta reduced the glycine proportion taken up by E. vaginatum, thus increasing niche overlap in N usage between these species. Local abundances of these species in mountain grasslands are principally controlled by grazing and soil moisture, although our results suggest that changes in the relative availability of ON to IN can also play a role. Our results also suggest that coexistence of these species in mountain grasslands is likely based on non-equilibrium mechanisms such as disturbance and/or soil heterogeneity.

  5. Respiration in ocean margin sediments

    NARCIS (Netherlands)

    Andersson, J.H.

    2007-01-01

    The aim of this thesis was the study of respiration in ocean margin sediments and the assessments of tools needed for this purpose. The first study was on the biological pump and global respiration patterns in the deep ocean using an empirical model based on sediment oxygen consumption data. In this

  6. Respiration in ocean margin sediments

    NARCIS (Netherlands)

    Andersson, J.H.

    2007-01-01

    The aim of this thesis was the study of respiration in ocean margin sediments and the assessments of tools needed for this purpose. The first study was on the biological pump and global respiration patterns in the deep ocean using an empirical model based on sediment oxygen consumption data.

  7. Light respiration in Chlorella sorokiniana

    NARCIS (Netherlands)

    Kliphuis, A.M.J.; Janssen, M.G.J.; End, van den E.J.; Martens, D.E.; Wijffels, R.H.

    2011-01-01

    Respiration and photosynthesis are two important processes in microalgal growth that occur simultaneously in the light. To know the rates of both processes, at least one of them has to be measured. To be able to measure the rate of light respiration of Chlorella sorokiniana, the measurement of oxyge

  8. Microbial communities in microcosm soils treated with battery waste

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Battery waste is one of the most destructive hazards to our environment, especially to the soil. In order to understand the effects of the battery waste on the microbial communities in soil, microcosm soils were treated with the powder made from the battery waste. Microbial biomass and respiration were measured after 15, 30, 45, and 60 days of the treatment, and catabolic capability and Biolog profile were determined after 60 days. Microbial biomass was declined by all treatments, while microbial respiration and catabolic capability were enhanced. Although microbial biomass recovered after a period of incubation, microbial respiratory quotient, catabolic capability and community structure remained significantly affected. Our results also suggest that microbial respiratory quotient and Biolog parameters are more sensitive than microbial biomass to the battery stress on bioavailability.

  9. Respiration in spiders (Araneae).

    Science.gov (United States)

    Schmitz, Anke

    2016-05-01

    Spiders (Araneae) are unique regarding their respiratory system: they are the only animal group that breathe simultaneously with lungs and tracheae. Looking at the physiology of respiration the existence of tracheae plays an important role in spiders with a well-developed tracheal system. Other factors as sex, life time, type of prey capture and the high ability to gain energy anaerobically influence the resting and the active metabolic rate intensely. Most spiders have metabolic rates that are much lower than expected from body mass; but especially those with two pairs of lungs. Males normally have higher resting rates than females; spiders that are less evolved and possess a cribellum have lower metabolic rates than higher evolved species. Freely hunting spiders show a higher energy turnover than spiders hunting with a web. Spiders that live longer than 1 year will have lower metabolic rates than those species that die after 1 year in which development and reproduction must be completed. Lower temperatures and starvation, which most spiders can cope with, will decrease the metabolic rate as well.

  10. From breathing to respiration.

    Science.gov (United States)

    Fitting, Jean-William

    2015-01-01

    The purpose of breathing remained an enigma for a long time. The Hippocratic school described breathing patterns but did not associate breathing with the lungs. Empedocles and Plato postulated that breathing was linked to the passage of air through pores of the skin. This was refuted by Aristotle who believed that the role of breathing was to cool the heart. In Alexandria, breakthroughs were accomplished in the anatomy and physiology of the respiratory system. Later, Galen proposed an accurate description of the respiratory muscles and the mechanics of breathing. However, his heart-lung model was hampered by the traditional view of two non-communicating vascular systems - veins and arteries. After a period of stagnation in the Middle Ages, knowledge progressed with the discovery of pulmonary circulation. The comprehension of the purpose of breathing progressed by steps thanks to Boyle and Mayow among others, and culminated with the contribution of Priestley and the discovery of oxygen by Lavoisier. Only then was breathing recognized as fulfilling the purpose of respiration, or gas exchange. A century later, a controversy emerged concerning the active or passive transfer of oxygen from alveoli to the blood. August and Marie Krogh settled the dispute, showing that passive diffusion was sufficient to meet the oxygen needs.

  11. Soil nitrogen status as a regulator of carbon substrate flows through microbial communities with elevated CO2

    Science.gov (United States)

    Ziegler, Susan E.; Billings, Sharon A.

    2011-03-01

    To assess how microbial processing of organic C inputs to forest soils may be influenced by elevated CO2 and altered N dynamics, we followed the fate of 13C-labeled substrates in soils from the Duke Free Air Carbon Enrichment site where differences in soil N status have been imposed by 7 years of N amendments. Heterotrophic respiration and δ13C of respired CO2-C and phospholipid fatty acids (PLFA) were measured to track activities of microbial groups and estimate a relative measure of substrate use efficiency (PLFA-based SUE). Results indicate an increased proportion of fungal and actinomycete activity in elevated CO2 soils, which varied with substrate. The negative effect of N on vanillin phenolic-C incorporation into actinomycete PLFA suggests legacies of fertilization can mitigate increased C flow into actinomycetes with elevated CO2. Further, the fourfold increase in PLFA-based SUE for vanillin phenolic-C in elevated CO2 soils that received N suggests future enhanced N limitation in elevated CO2 soils may promote enhanced respiratory loss relative to incorporation of some C-substrates into microbial biomass. These short-term incubations did not reveal greater loss of soil organic carbon via respiration or shifts in SUE with elevated CO2. However, observed relative increases in activity of actinomycetes and fungi with elevated CO2 and mitigation of this effect on actinomycetes with N amendments suggests that elevated CO2 and predicted N limitation may alter the fate of slow-turnover soil organic matter (SOM) in two competing ways. Investigations need to focus on how these microorganisms may increase slow-turnover substrate use while possibly enhancing the prevalence of microbial cell wall structures that can serve as precursors of stabilized SOM.

  12. Responses of soil respiration and its temperature/moisture sensitivity to precipitation in three subtropical forests in southern China

    Directory of Open Access Journals (Sweden)

    H. Jiang

    2013-06-01

    Full Text Available Both long-term observation data and model simulations suggest an increasing chance of serious drought in the dry season and extreme flood in the wet season in southern China, yet little is known about how changes in precipitation pattern will affect soil respiration in the region. We conducted a field experiment to study the responses of soil respiration to precipitation manipulations – precipitation exclusion to mimic drought, double precipitation to simulate flood, and ambient precipitation as control (abbr. EP, DP and AP, respectively – in three subtropical forests in southern China. The three forest sites include Masson pine forest (PF, coniferous and broad-leaved mixed forest (MF and monsoon evergreen broad-leaved forest (BF. Our observations showed that altered precipitation strongly influenced soil respiration, not only through the well-known direct effects of soil moisture on plant and microbial activities, but also by modification of both moisture and temperature sensitivity of soil respiration. In the dry season, soil respiration and its temperature sensitivity, as well as fine root and soil microbial biomass, showed rising trends with precipitation increases in the three forest sites. Contrarily, the moisture sensitivity of soil respiration decreased with precipitation increases. In the wet season, different treatments showed different effects in three forest sites. The EP treatment decreased fine root biomass, soil microbial biomass, soil respiration and its temperature sensitivity, but enhanced soil moisture sensitivity in all three forest sites. The DP treatment significantly increased soil respiration, fine root and soil microbial biomass in the PF only, and no significant change was found for the soil temperature sensitivity. However, the DP treatment in the MF and BF reduced soil temperature sensitivity significantly in the wet season. Our results indicated that soil respiration would decrease in the three subtropical

  13. The contribution of root respiration to soil CO2 efflux in Puccinellia tenuiflora dominated community in a semi-arid meadow steppe

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this study, the linear regression between soil respiration rate and root biomass was adopted to estimate the contribution of root respiration to total soil respiration in Puccinellia tenuiflora dominated community of a semi-arid meadow steppe in northeast China. The soil respiration rate reached the maximum value 2.45μmol·m-2·s-1 in late June and the minimum value 0.39 μmol·m-2·s-1 in late September. Soil temperature is the major environmental factor controlling the seasonal variation of soil respiration. The root biomass ranged from 0.54 to 0.97 kg·m-2, showing insignificant seasonal variation. Microbial biomass C reached the maximum value 0.50 g·m-2 in mid August, presenting the least within- site variation. The pattern of seasonal change in root respiration rate was different from that in microbial respiration. Root respiration rate ranged from 0.19 μmol·m-2·s-1 in May, to the maximum value 1.39μmol·m-2·s-1 in late June, then down to 0.28 μmol·m-2·s-1 in late September; whereas, microbial respiration rate ranged from 0.61 μmol·m-2·s-1 in May, to the maximum value 1.27 μmol·m-2·s-1 in July, then down to 0.11 μmol·m-2·s-1 in late Sep- tember. There was a significant exponential correla- tion between microbial respiration rate and soil tem- perature, whereas not so for root respiration rate. We estimated that the contribution of root respiration to total soil respiration ranged within 24%-57% in spring and summer, and increased to 73% in autumn.

  14. Experimental warming effects on the microbial community of a temperate mountain forest soil

    OpenAIRE

    Schindlbacher, A.; Rodler, A.; Kuffner, M.; Kitzler, B.; Sessitsch, A; Zechmeister-Boltenstern, S.

    2011-01-01

    Soil microbial communities mediate the decomposition of soil organic matter (SOM). The amount of carbon (C) that is respired leaves the soil as CO2 (soil respiration) and causes one of the greatest fluxes in the global carbon cycle. How soil microbial communities will respond to global warming, however, is not well understood. To elucidate the effect of warming on the microbial community we analyzed soil from the soil warming experiment Achenkirch, Austria. Soil of a mature spruce forest was ...

  15. Mathematical Competences

    DEFF Research Database (Denmark)

    Westphael, Henning; Mogensen, Arne

    2013-01-01

    In this article we present the notion of Mathematical competences as a tool to describe the mathematically gifted students.......In this article we present the notion of Mathematical competences as a tool to describe the mathematically gifted students....

  16. Microbial growth responses upon rewetting dry soil

    Science.gov (United States)

    Meisner, Annelein; Rousk, Johannes; Bååth, Erland

    2015-04-01

    Increased rainfall and drought periods are expected to occur with current climate change, leading to fluctuations in soil moisture. Changes in soil moisture are known to affect carbon cycling. A pulse of carbon dioxide release (respiration) is often observed after rewetting a dry soil and a drying threshold is observed before this pulse emerges. Increased microbial activity is often assumed to be the cause for the pulse in respiration. Yet, the microbial growth responses that underlie this pulse are often not studied. The following questions will be addressed in this presentation. 1) Do fungal and bacterial growth explain the pulse in respiration upon rewetting a dry soil? 2) How does microbial growth respond to different drying intensities before rewetting? To answer the research questions, soils from Sweden, U.K. and Greenland were put in microcosms, air-dried for four days, a prolonged period or to different moisture content before rewetting. We measured soil respiration, fungal growth rates and/or bacterial growth rates at high temporal resolution during one week after rewetting. Our results suggest that the respiration pulse upon rewetting dry soil is not due to high microbial growth rates. During the first hours after rewetting, bacterial and fungal growth rates were low whereas the respiration rates were high. As such, there was a decoupling between the pulse in respiration and microbial growth rates. Two patterns of bacterial growth were observed upon rewetting the three different soils. In "pattern 1", bacteria started growing immediately in a linear pattern up to values similar as the moist control. In "pattern 2", bacteria started growing exponentially after a lag period of no growth with a second pulse of respiration occurring at the start of bacterial growth. Manipulating the drying intensity changed the patterns. Soils with "pattern 1" were changed to "pattern 2" when subjected to more extensive drying periods whereas soils with "pattern 2" were

  17. Modelling autotrophic and heterotrophic components of soil respiration in wheat fields

    Science.gov (United States)

    Delogu, E.; LeDantec, V.; Buysse, P.; Mordelet, P.; Aubinet, M.

    2012-04-01

    Partitioning soil respiration into its heterotrophic and autotrophic components is a current key challenge to improve understanding of soil processes in croplands. For this purpose, we coupled a daily-time step soil organic carbon model derived from the CENTURY (Parton et al, 1987) calculating carbon turnover and carbon dioxide production in the soil with root sub-model from the plant process-based model CASTANEA (Dufrêne et al, 2005). In the Century model, soil organic carbon is divided into three major components including active, slow and passive soil carbon. Each pool has its own decomposition constant. Carbon flows between these pools are controlled by carbon inputs (crop residue), decomposition rate and microbial respiration loss parameters, both of which are a function of soil texture, soil temperature and soil water content. The model assumes that all C decompositions flows are associated with microbial activity and that microbial respiration occurs for each of these flows. Heterotrophic soil respiration is the sum of all these microbial respiration processes. To simulate autotrophic component, maintenance respiration is calculated from the nitrogen content and assuming an exponential relationship to account for temperature dependence. Growth respiration is calculated assuming that daily growth respiration depends on both growth rate and construction cost of the considered organ. To investigate model performances, simulations of soil CO2 efflux were compared with 3 datasets recorded in three different fields under different soil and climate conditions. Soil respiration measurements were performed on three winter wheat crops on Lamasquère (2007) and Auradé (2008), South-West France and in Lonzée (2007), Belgium. The French sites data come from manual measurement chambers, PP systems. The Belgium site is equipped with an automatic (half-hour resolution time) measurement system. The model was run on the three climatic years of data on bare soil and a first

  18. Experimental warming effects on the microbial community of a temperate mountain forest soil.

    Science.gov (United States)

    Schindlbacher, A; Rodler, A; Kuffner, M; Kitzler, B; Sessitsch, A; Zechmeister-Boltenstern, S

    2011-07-01

    Soil microbial communities mediate the decomposition of soil organic matter (SOM). The amount of carbon (C) that is respired leaves the soil as CO(2) (soil respiration) and causes one of the greatest fluxes in the global carbon cycle. How soil microbial communities will respond to global warming, however, is not well understood. To elucidate the effect of warming on the microbial community we analyzed soil from the soil warming experiment Achenkirch, Austria. Soil of a mature spruce forest was warmed by 4 °C during snow-free seasons since 2004. Repeated soil sampling from control and warmed plots took place from 2008 until 2010. We monitored microbial biomass C and nitrogen (N). Microbial community composition was assessed by phospholipid fatty acid analysis (PLFA) and by quantitative real time polymerase chain reaction (qPCR) of ribosomal RNA genes. Microbial metabolic activity was estimated by soil respiration to biomass ratios and RNA to DNA ratios. Soil warming did not affect microbial biomass, nor did warming affect the abundances of most microbial groups. Warming significantly enhanced microbial metabolic activity in terms of soil respiration per amount of microbial biomass C. Microbial stress biomarkers were elevated in warmed plots. In summary, the 4 °C increase in soil temperature during the snow-free season had no influence on microbial community composition and biomass but strongly increased microbial metabolic activity and hence reduced carbon use efficiency.

  19. Genome-Enabled Modeling of Biogeochemical Processes Predicts Metabolic Dependencies that Connect the Relative Fitness of Microbial Functional Guilds

    Science.gov (United States)

    Brodie, E.; King, E.; Molins, S.; Karaoz, U.; Steefel, C. I.; Banfield, J. F.; Beller, H. R.; Anantharaman, K.; Ligocki, T. J.; Trebotich, D.

    2015-12-01

    Pore-scale processes mediated by microorganisms underlie a range of critical ecosystem services, regulating carbon stability, nutrient flux, and the purification of water. Advances in cultivation-independent approaches now provide us with the ability to reconstruct thousands of genomes from microbial populations from which functional roles may be assigned. With this capability to reveal microbial metabolic potential, the next step is to put these microbes back where they belong to interact with their natural environment, i.e. the pore scale. At this scale, microorganisms communicate, cooperate and compete across their fitness landscapes with communities emerging that feedback on the physical and chemical properties of their environment, ultimately altering the fitness landscape and selecting for new microbial communities with new properties and so on. We have developed a trait-based model of microbial activity that simulates coupled functional guilds that are parameterized with unique combinations of traits that govern fitness under dynamic conditions. Using a reactive transport framework, we simulate the thermodynamics of coupled electron donor-acceptor reactions to predict energy available for cellular maintenance, respiration, biomass development, and enzyme production. From metagenomics, we directly estimate some trait values related to growth and identify the linkage of key traits associated with respiration and fermentation, macromolecule depolymerizing enzymes, and other key functions such as nitrogen fixation. Our simulations were carried out to explore abiotic controls on community emergence such as seasonally fluctuating water table regimes across floodplain organic matter hotspots. Simulations and metagenomic/metatranscriptomic observations highlighted the many dependencies connecting the relative fitness of functional guilds and the importance of chemolithoautotrophic lifestyles. Using an X-Ray microCT-derived soil microaggregate physical model combined

  20. Draft Genome Sequence of Desulfuromonas acetexigens Strain 2873, a Novel Anode-Respiring Bacterium

    KAUST Repository

    Katuri, Krishna

    2017-03-03

    Here, we report the draft genome sequence of Desulfuromonas acetexigens strain 2873, which was originally isolated from digester sludge from a sewage treatment plant in Germany. This bacterium is capable of anode respiration with high electrochemical activity in microbial electrochemical systems. The draft genome contains 3,376 predicted protein-coding genes and putative multiheme c-type cytochromes.

  1. Vegetation and environmental controls on soil respiration in a pinon-juniper woodland

    Science.gov (United States)

    Sandra A. White

    2008-01-01

    Soil respiration (RS) responds to changes in plant and microbial activity and environmental conditions. In arid ecosystems of the southwestern USA, soil moisture exhibits large fluctuations because annual and seasonal precipitation inputs are highly variable, with increased variability expected in the future. Patterns of soil moisture, and periodic severe drought, are...

  2. Decreased carbon limitation of litter respiration in a mortality-affected pinon-juniper woodland

    Science.gov (United States)

    Erin Berryman; John D. Marshall; Thom Rahn; Marcie Litvak; John Butnor

    2013-01-01

    Microbial respiration depends on microclimatic variables and carbon (C) substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting pinon-juniper ecosystems in southwestern North America, may affect C substrate availability in several ways, for example, via litterfall pulses and loss of...

  3. Soil Respiration Responses to Variation in Temperature Treatment and Vegetation Type

    Science.gov (United States)

    Liu, S.; Pavao-zuckerman, M.

    2013-12-01

    Complex linkages exist between terrestrial vegetation, soil moisture, soil organic matter (SOM), local climate, and soil microorganisms. Thus, large-scale changes in vegetation, such as the woody plant encroachment observed in many historically semiarid and arid grasslands worldwide, could potentially alter the flux of carbon from soil reserves to the atmosphere. Mathematical models that attempt to project the long-term impact of vegetative shifts on soil fluxes largely rely on assumptions such as first-order donor control rather than incorporate the biological aspects of soil respiration such as microbial activity. To examine the impact of vegetation type on soil physicochemical properties and soil microbial respiration and provide experimental data to refine existing predictive models, we compared soil (ground basalt from northern Arizona) in mesocosms established with no vegetation, velvet mesquites (Prosopis velutina; woody shrub), or sideoats gramas (Bouteloua curtipendula; grass) for 2 years, The temperature sensitivity of soil respiration was examined by incubating soil (0-10 and 10-30 cm depth fractions) from each vegetation treatment at 10, 20, 30, and 40 °C for 24 hours. Vegetated soils contained more SOM (~0.1% for mesquite and grass mesocosms) than non-vegetated soils (~0.02%). Respiration rates were generally highest from grass-established soils, intermediate from mesquite-established soils, and lowest from non-vegetated soils. Respiration rates of samples incubated without the addition of substrate peaked at approximately 30 °C, whereas respiration rates of samples incubated with dextrose were highest at 40 °C. Further, the respiration assays suggest that while respiration rates are overall higher in grass-established soils, mesquite-established soils are more temperature sensitive which may have significant implications in the context of global warming and current fire management practices.

  4. General Instructions for Disposable Respirators

    Centers for Disease Control (CDC) Podcasts

    2009-04-09

    This podcast, intended for the general public, demonstrates how to put on and take off disposable respirators that are to be used in areas affected by the influenza outbreak.  Created: 4/9/2009 by CDC, National Institute for Occupational Safety and Health (NIOSH).   Date Released: 4/29/2009.

  5. Use of Facemasks and Respirators

    Centers for Disease Control (CDC) Podcasts

    2007-05-15

    This program demonstrates the differences of facemasks and respirators that are to be used in public settings during an influenza pandemic.  Created: 5/15/2007 by CDC, National Institute for Occupational Safety and Health (NIOSH).   Date Released: 5/25/2007.

  6. Carbon balance of a subarctic meadow under 3 r{ C warming - unravelling respiration}

    Science.gov (United States)

    Silvennoinen, Hanna; Bárcena, Téresa G.; Moni, Christophe; Szychowski, Marcin; Rajewicz, Paulina; Höglind, Mats; Rasse, Daniel P.

    2016-04-01

    Boreal and arctic terrestrial ecosystems are central to the climate change debate, as the warming is expected to be disproportionate as compared to world averages. Northern areas contain large terrestrial carbon (C) stocks further increasing the interest in the C cycle's fate in changing climate. In 2013, we started an ecosystem warming experiment at a meadow in Eastern Finnmark, NE Norway. The meadow was on a clay soil and its vegetation was common meadow grasses and clover. Typical local agronomy was applied. The study site featured ten 4m-wide hexagonal plots, five control and five actively warmed plots in randomized complete block design. Each of the warmed plots was continuously maintained 3 ° C above its associated control plot with infrared heaters controlled by canopy thermal sensors. In 2014-2015, we measured net ecosystem exchange (NEE) and respiration twice per week during growth seasons from preinstalled collars of each site with dynamic, temperature-controlled chambers combined to an infrared analyzer. Despite warming-induced differences in yield, species composition and root biomass, neither the NEE nor the respiration responded to the warming, all sites remaining equal sinks for C. Following this observation, we carried out an additional experiment in 2015 where we aimed at partitioning the total CO2 flux to microbial and plant respiration as well as at recording the growth season variation of those parameters in situ. Here, we used an approach based on natural abundances of 13C. The δ13C signature of both autotrophic plant respiration and heterotrophic microbial respiration were obtained in targeted incubations (Snell et al. 2014). Then, the δ13C -signature of the total soil respiration was determined in the field by Keeling approach with dynamic dark chambers combined to CRDS. Proportions of autotrophic and heterotrophic components in total soil respiration were then derived based on 13C mixing model. Incubations were repeated at early, mid and

  7. Soil Respiration: Concept and Measurement Methods

    Directory of Open Access Journals (Sweden)

    SANDOR M.

    2010-08-01

    Full Text Available Soil respiration is the main element in the carbon cycle that makes possible for plants carbon plants to return inthe atmosphere. The objective of this work was to present and discuss some aspects of the soil CO2 efflux. We definedherein, some terms associated to the soil respiration concept, we tackled some aspects regarding the influence oftemperature, humidity and soil pH on soil respiration and we presented the principle of soil respiration measurement byusing dynamic closed chamber system.

  8. 30 CFR 57.5044 - Respirators.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Respirators. 57.5044 Section 57.5044 Mineral... Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5044 Respirators. In environments exceeding 1.0 WL, miners shall wear respirators approved by NIOSH for radon daughters prior to July 10,...

  9. The Midbrain Periaqueductal Gray Control of Respiration

    NARCIS (Netherlands)

    Subramanian, Hari H.; Balnave, Ron J.; Holstege, Gert

    2008-01-01

    The midbrain periaqueductal gray (PAG) organizes basic survival behavior, which includes respiration. How the PAG controls respiration is not known. We studied the PAG control of respiration by injecting D,L-homocysteic acid in the PAG in unanesthetized precollicularly decerebrated cats. Injections

  10. Molecular Characterization of Bacterial Respiration on Minerals

    Energy Technology Data Exchange (ETDEWEB)

    Blake, Robert C.

    2013-04-26

    The overall aim of this project was to contribute to our fundamental understanding of proteins and biological processes under extreme environmental conditions. We sought to define the biochemical and physiological mechanisms that underlie biodegradative and other cellular processes in normal, extreme, and engineered environments. Toward that end, we sought to understand the substrate oxidation pathways, the electron transport mechanisms, and the modes of energy conservation employed during respiration by bacteria on soluble iron and insoluble sulfide minerals. In accordance with these general aims, the specific aims were two-fold: To identify, separate, and characterize the extracellular biomolecules necessary for aerobic respiration on iron under strongly acidic conditions; and to elucidate the molecular principles whereby these bacteria recognize and adhere to their insoluble mineral substrates under harsh environmental conditions. The results of these studies were described in a total of nineteen manuscripts. Highlights include the following: 1. The complete genome of Acidithiobacillus ferrooxidans ATCC 23270 (type strain) was sequenced in collaboration with the DOE Joint Genome Institute; 2. Genomic and mass spectrometry-based proteomic methods were used to evaluate gene expression and in situ microbial activity in a low-complexity natural acid mine drainage microbial biofilm community. This was the first effort to successfully analyze a natural community using these techniques; 3. Detailed functional and structural studies were conducted on rusticyanin, an acid-stable electron transfer protein purified from cell-free extracts of At. ferrooxidans. The three-dimensional structure of reduced rusticyanin was determined from a combination of homonuclear proton and heteronuclear 15N- and 13C-edited NMR spectra. Concomitantly, the three-dimensional structure of oxidized rusticyanin was determined by X-ray crystallography to a resolution of 1.9 A by multiwavelength

  11. Effects of experimental warming and nitrogen addition on soil respiration and CH4 fluxes from crop rotations of winter wheat–soybean/fallow

    DEFF Research Database (Denmark)

    Liu, L; Hu, C; Yang, P;

    2015-01-01

    Soil respiration and CH4 emissions play a significant role in the global carbon balance. However, in situ studies in agricultural soils on responses of soil respiration and CH4 fluxes to climate warming are still sparse, especially from long-term studies with year-round heating. A warming...... by affecting soil NH4 concentration. Across years, CH4 emissions were negatively correlated with soil temperature in N1 treatment. Soil respiration showed clear seasonal fluctuations, with the largest emissions during summer and smallest in winter. Warming and nitrogen fertilization had no significant effects...... on total cumulative soil CO2 fluxes. Soil respiration was positively correlated with microbial biomass C, and microbial biomass C was not affected significantly by warming or nitrogen addition. The lack of significant effects of warming on soil respiration may have resulted from: (1) warming-induced soil...

  12. Outsourcing competence

    NARCIS (Netherlands)

    Bergstra, J.; Delen, G.; van Vlijmen, B.

    2011-01-01

    The topic of this paper, competences needed for outsourcing, is organized by first providing a generic competence scheme, which is subsequently instantiated to the area of sourcing and outsourcing. Sourcing and outsourcing are positioned as different areas of activity, neither one of which is

  13. Timespacing competence

    DEFF Research Database (Denmark)

    Laursen, Helle Pia; Mogensen, Naja Dahlstrup

    2016-01-01

    Drawing on Kramsch’s (2009) conceptualization of the multilingual subject and the symbolic self, in this paper, we explore how multilingual children re-signify three intertwined myths about the bilingual student, linguistic diversity and language competence, when, in the researcher-generated acti......Drawing on Kramsch’s (2009) conceptualization of the multilingual subject and the symbolic self, in this paper, we explore how multilingual children re-signify three intertwined myths about the bilingual student, linguistic diversity and language competence, when, in the researcher....... By perceiving competences from a subjective child perspective, we learn how children do what we call timespacing competence. On that basis, we suggest paying attention to how children themselves timespace competence by focusing (more consistently) on the subjective, social, spatial and temporal dimensions...

  14. Mesoporous silica nanoparticles inhibit cellular respiration.

    Science.gov (United States)

    Tao, Zhimin; Morrow, Matthew P; Asefa, Tewodros; Sharma, Krishna K; Duncan, Cole; Anan, Abhishek; Penefsky, Harvey S; Goodisman, Jerry; Souid, Abdul-Kader

    2008-05-01

    We studied the effect of two types of mesoporous silica nanoparticles, MCM-41 and SBA-15, on mitochondrial O 2 consumption (respiration) in HL-60 (myeloid) cells, Jurkat (lymphoid) cells, and isolated mitochondria. SBA-15 inhibited cellular respiration at 25-500 microg/mL; the inhibition was concentration-dependent and time-dependent. The cellular ATP profile paralleled that of respiration. MCM-41 had no noticeable effect on respiration rate. In cells depleted of metabolic fuels, 50 microg/mL SBA-15 delayed the onset of glucose-supported respiration by 12 min and 200 microg/mL SBA-15 by 34 min; MCM-41 also delayed the onset of glucose-supported respiration. Neither SBA-15 nor MCM-41 affected cellular glutathione. Both nanoparticles inhibited respiration of isolated mitochondria and submitochondrial particles.

  15. Plastron Respiration Using Commercial Fabrics

    OpenAIRE

    2014-01-01

    A variety of insect and arachnid species are able to remain submerged in water indefinitely using plastron respiration. A plastron is a surface-retained film of air produced by surface morphology that acts as an oxygen-carbon dioxide exchange surface. Many highly water repellent and hydrophobic surfaces when placed in water exhibit a silvery sheen which is characteristic of a plastron. In this article, the hydrophobicity of a range of commercially available water repellent fabrics and polymer...

  16. 头孢噻肟污染条件下土壤呼吸、部分酶活性的短期响应及土壤细菌PCR-DGGE分析%Short-term response of soil microbial respiration, enzyme activities, bacteria population and PCR-DGGE profiles of bacterial communities to cefotaxime pollution

    Institute of Scientific and Technical Information of China (English)

    姚振飞; 魏松林; 梅丽娟; 胡健

    2013-01-01

    采用常规土壤酶活力测定方法、平板菌落计数法以及PCR-DGGE技术,分析头孢噻肟污染对土壤呼吸作用、部分酶活性、细菌数量以及细菌多样性的短期影响.结果表明:①头孢噻肟明显刺激处理后1~14 d土壤呼吸强度,处理21d后刺激作用消失;头孢噻肟明显提高处理后1、18 d土壤脲酶活性,处理后3、7d抑制作用明显;不同浓度头孢噻肟处理初期,土壤过氧化氢酶活力均受到抑制,随着培养时间的延长抑制率下降,并且低、中浓度头孢噻肟处理分别在处理后3、7d开始表现出对过氧化氢酶一定程度的刺激作用.②培养1~3 d,各处理对土壤细菌数量具有一定的刺激作用,7d后中、高浓度处理对土壤细菌有一定抑制作用,而18 d后各浓度处理土壤细菌数量基本恢复到对照水平.③采用Quantity One 4.6(Bio-Rad)软件,对PCR-DGGE图谱中各处理1、18 d条带进行分析,发现头孢噻肟处理对样品可检测条带数没有影响,但对处理初期细菌优势种群丰度产生影响,此后逐渐恢复到对照水平.总之,头孢噻肟污染对供试土壤微生物活性、细菌数量以及优势种群的丰度具有不同程度的短期影响,但随着时间的延长,影响逐渐消失.%The short-term effect of cefotaxime at three dosage levels:low (LC,10 mg · kg-1),medium (MC,50 mg · kg-1) and high (HC,200 mg· kg-1) on the soil microbial respiration,enzyme activities,bacteria population and PCR-DGGE profiles of bacterial communities were studied by general measuring methods of soil respiraition and enzyme activity,plate culture count methods and PCR-DGGE techniques.Results showed that:① The soil microbial respiration was significantly stimulated by cefotaxime treated after 1 to 14 days but turned to the normal level 21 days after treatment.The soil urease activity was significantly stimulated by cefotaxine treated after 1 day and 18 days but significantly inhibited after 3 days and 7

  17. The Effects of Long Term Nitrogen Fertilization on Soil Respiration in Rocky Mountain National Park

    Science.gov (United States)

    Allen, J.; Denning, S.; Baron, J.

    2015-12-01

    Anthropogenic activities contribute to increased levels of nitrogen deposition and elevated CO2 concentrations in terrestrial ecosystems. The role that soils play in biogeochemical cycles is an important area of uncertainty in ecosystem ecology. One of the main reasons for this uncertainty is that we have limited understanding of belowground microbial activity and how this activity is linked to soil processes. In particular, elevated CO2 may influence soil nitrogen processes that regulate nitrogen availability to plants. Warming and nitrogen fertilization may both contribute to loss of stored carbon from mountain ecosystems, because they contribute to microbial decomposition of organic matter. To study the effects of long-term nitrogen fertilization on soil respiration, we analyzed results from a 25-year field experiment in Rocky Mountain National Park. Field treatments are in old growth Engelmann spruce forests. Soil respiration responses to the effects of nitrogen fertilization on soil carbon cycling, via respiration, were investigated during the 2013 growing season. Soil moisture, temperature, and respiration rates were measured in six 30 x 30 m plots, of the six plots three are fertilized with 25 kg N ha-1 yr-1 as ammonium nitrate (NH4NO3) pellets and three receives ambient atmospheric nitrogen deposition (1-6 kg N/ha/yr) in Rocky Mountain National Park. We found that respirations rates in the fertilized plots were not significantly higher than respiration rates in the unfertilized plots. We speculate that acclimation to long-term fertilization and relatively high levels of nitrogen deposition in the control plots both contribute to the insensitivity of soil respiration to fertilization at this site.

  18. Soil respiration sensitivities to water and temperature in a revegetated desert

    Science.gov (United States)

    Zhang, Zhi-Shan; Dong, Xue-Jun; Xu, Bing-Xin; Chen, Yong-Le; Zhao, Yang; Gao, Yan-Hong; Hu, Yi-Gang; Huang, Lei

    2015-04-01

    Soil respiration in water-limited ecosystems is affected intricately by soil water content (SWC), temperature, and soil properties. Eight sites on sand-fixed dunes that revegetated in different years since 1950s, with several topographical positions and various biological soil crusts (BSCs) and soil properties, were selected, as well as a moving sand dune (MSD) and a reference steppe in the Tengger Desert of China. Intact soil samples of 20 cm in depth were taken and incubated randomly at 12 levels of SWC (0 to 0.4 m3 m-3) and at 9 levels of temperature (5 to 45°C) in a growth chamber; additionally, cryptogamic and microbial respirations (RM) were measured. Total soil respiration (RT, including cryptogamic, microbial, and root respiration) was measured for 2 years at the MSD and five sites of sand-fixed dunes. The relationship between RM and SWC under the optimal SWC condition (0.25 m3 m-3) is linear, as is the entire range of RT and SWC. The slope of linear function describes sensitivity of soil respiration to water (SRW) and reflects to soil water availability, which is related significantly to soil physical properties, BSCs, and soil chemical properties, in decreasing importance. Inversely, Q10 for RM is related significantly to abovementioned factors in increasing importance. However, Q10 for RT and respiration rate at 20°C are related significantly to soil texture and depth of BSCs and subsoil only. In conclusion, through affecting SRW, soil physical properties produce significant influences on soil respiration, especially for RT. This indicates that a definition of the biophysical meaning of SRW is necessary, considering the water-limited and coarse-textured soil in most desert ecosystems.

  19. Competence Building

    DEFF Research Database (Denmark)

    Borrás, Susana; Edquist, Charles

    on the one hand, and the real world of innovation policy-making on the other, typically not speaking to each other. With this purpose in mind, this paper discusses the role of competences and competence-building in the innovation process from a perspective of innovation systems; it examines how governments...... and public agencies in different countries and different times have actually approached the issue of building, maintaining and using competences in their innovation systems; it examines what are the critical and most important issues at stake from the point of view of innovation policy, looking particularly...

  20. Effects of Vegetation Type and Management Practice on Soil Respiration of Grassland in Northern Japan

    Directory of Open Access Journals (Sweden)

    Minaco Adachi

    2013-01-01

    Full Text Available Soil respiration rate in two types of grassland dominated with Zoysia japonica and Miscanthus sinensis, respectively, and under two management practices (undisturbed and intentionally burned for the M. sinensis grassland was investigated for understanding the effects of grassland vegetation type and management practices on the relationship between soil temperature and soil respiration in northern Japan. Soil temperatures at depth of 1 cm in the Z. japonica (ZJ and burned M. sinensis (MSb plots had a larger temporal variation than that in the control M. sinensis (MSc plot prior to early July. However, the coefficient of temperature sensitivity ( values, based on soil respiration rates and soil temperatures at 5 cm depth in the ZJ and MSb plots, were 1.3 and 2.9. These rates were lower than that in the MSc plot (4.3, meaning that soil respiration showed lower activity to an increase in soil temperature in the ZJ and MSb plots. In addition, monthly carbon fluxes from soil in these plots were smaller than that in the MSc plot. These results suggested that artificial disturbance would decrease soil microbial or/and plant root respiration, and it would contribute to the plant productivity. Future studies should examine the effects of the intensity and period of management on the soil respiration rate.

  1. Soil and ecosystem respiration responses to grazing, watering and experimental warming chamber treatments across topographical gradients in northern Mongolia.

    Science.gov (United States)

    Sharkhuu, Anarmaa; Plante, Alain F; Enkhmandal, Orsoo; Gonneau, Cédric; Casper, Brenda B; Boldgiv, Bazartseren; Petraitis, Peter S

    2016-05-01

    Globally, soil respiration is one of the largest fluxes of carbon to the atmosphere and is known to be sensitive to climate change, representing a potential positive feedback. We conducted a number of field experiments to study independent and combined impacts of topography, watering, grazing and climate manipulations on bare soil and vegetated soil (i.e., ecosystem) respiration in northern Mongolia, an area known to be highly vulnerable to climate change and overgrazing. Our results indicated that soil moisture is the most important driving factor for carbon fluxes in this semi-arid ecosystem, based on smaller carbon fluxes under drier conditions. Warmer conditions did not result in increased respiration. Although the system has local topographical gradients in terms of nutrient, moisture availability and plant species, soil respiration responses to OTC treatments were similar on the upper and lower slopes, implying that local heterogeneity may not be important for scaling up the results. In contrast, ecosystem respiration responses to OTCs differed between the upper and the lower slopes, implying that the response of vegetation to climate change may override microbial responses. Our results also showed that light grazing may actually enhance soil respiration while decreasing ecosystem respiration, and grazing impact may not depend on climate change. Overall, our results indicate that soil and ecosystem respiration in this semi-arid steppe are more sensitive to precipitation fluctuation and grazing pressure than to temperature change.

  2. Soil and ecosystem respiration responses to grazing, watering and experimental warming chamber treatments across topographical gradients in northern Mongolia

    Science.gov (United States)

    Sharkhuu, Anarmaa; Plante, Alain F.; Enkhmandal, Orsoo; Gonneau, Cédric; Casper, Brenda B.; Boldgiv, Bazartseren; Petraitis, Peter S.

    2017-01-01

    Globally, soil respiration is one of the largest fluxes of carbon to the atmosphere and is known to be sensitive to climate change, representing a potential positive feedback. We conducted a number of field experiments to study independent and combined impacts of topography, watering, grazing and climate manipulations on bare soil and vegetated soil (i.e., ecosystem) respiration in northern Mongolia, an area known to be highly vulnerable to climate change and overgrazing. Our results indicated that soil moisture is the most important driving factor for carbon fluxes in this semi-arid ecosystem, based on smaller carbon fluxes under drier conditions. Warmer conditions did not result in increased respiration. Although the system has local topographical gradients in terms of nutrient, moisture availability and plant species, soil respiration responses to OTC treatments were similar on the upper and lower slopes, implying that local heterogeneity may not be important for scaling up the results. In contrast, ecosystem respiration responses to OTCs differed between the upper and the lower slopes, implying that the response of vegetation to climate change may override microbial responses. Our results also showed that light grazing may actually enhance soil respiration while decreasing ecosystem respiration, and grazing impact may not depend on climate change. Overall, our results indicate that soil and ecosystem respiration in this semi-arid steppe are more sensitive to precipitation fluctuation and grazing pressure than to temperature change. PMID:28239190

  3. A mechanistic model of microbial competition in the rhizosphere of wetland plants

    Science.gov (United States)

    Aslkhodapasand, F.; Mayer, K. U.; Neumann, R. B.

    2014-12-01

    Wetlands are the largest natural source of methane to the atmosphere. Although they cover only 4-6% of earth's surface, wetlands contribute 20-39% of global methane emissions. Hollow aerenchyma tissues inside the roots, stems and leaves of plants represent one of the most important methane emission pathways for wetlands. Up to 90% of the emitted methane can diffuse through these hollow tissues that directly connect the atmosphere to the anoxic soils where methane is generated. Thus, concentrations of methane surrounding plant roots directly impact the amount of methane emitted by wetlands. Methane concentrations are controlled by a variety of microbial processes occurring in the soil around the roots of plants (aka the rhizosphere). The rhizosphere is a microbial hotspot sustained by plant inputs of organic carbon and oxygen; plant roots exude excess organic carbon generated in photosynthesis into the rhizosphere and atmospheric oxygen diffuses down to the rhizosphere through the hollow aerenchyma tissues. This environment supports a variety of microbial communities that compete with each other for available carbon and oxygen, including methanogens, methanotrophs, and heterotrophs. Methanogens ferment organic carbon into methane, a reaction that is inhibited by oxygen; methanotrophs use oxygen to oxidize methane into carbon dioxide; and heterotrophs use oxygen to oxidize organic carbon into carbon dioxide. We are interested in understanding how competition between these communities alters methane concentrations and responds to variations in plant inputs. To this end, we have developed a mechanistic root-scale model that describes microbial competition for organic carbon and oxygen in the rhizosphere of wetland plants. Our results focus on variations in rates of methane production, methane oxidation, heterotrophic respiration, and diffusion of methane into plant roots as a result of changes in carbon and oxygen inputs. The study provides insight into how plant

  4. Effects of understory removal on soil respiration and microbial community composition structure in a Chinese fir plantation%林下植被剔除对杉木林土壤呼吸和微生物群落结构的影响

    Institute of Scientific and Technical Information of China (English)

    贺同鑫; 李艳鹏; 张方月; 王清奎

    2015-01-01

    AimsSoil respiration (Rs) is the largest fraction of carbon flux in forest ecosystems, but the effects of forest un-derstory removal onRs in Chinese fir (Cunninghamia lanceolate) plantations is poorly understood. In order to quantify the effects of forest understory removal onRs and microbial community composition, a field experiment was conducted in a subtropical Chinese fir plantation. MethodsForest understory was removed manually in June 2012.Rs was measured monthly using a LI-COR 8100 infrared gas analyzer from July 2012 through July 2014. Soil temperature and moisture were also measured at 5 cm depth at the time ofRs measurements. Surface soil (0–10 cm) samples were collected in July 2013 and 2014, respectively, and the soil microbial community structures were determined by phospholipid fatty acids (PLFAs) analysis. Important findings Rs decreased by 32.8% over a two-year period following understory removal (UR), with a greater rate of decrease in the first year (42.9%) than in the second year (22.2%). The temperature sensitivity ofRs was affected by UR, and was 2.10 and 1.87 in the control and UR plots, respectively. UR significantly reduced the concentration of fungal PLFAs by 18.3%, but did not affect the concentration of bacterial PLFAs, resulting in an increase in the fungal:bacterial ratio; it significantly increased the concentration of gram-positive bacterial PLFAs by 24.5%, and the ratio of gram-positive to gram-negative bacterial PLFAs after one year of treatment, but decreased the concentration of gram-positive bacterial PLFAs by 9.4% and the ratio of gram-positive to gram-negative bacterial PLFAs after two years of treatment. The results suggested thatRs and microbial commu-nity composition were both affected by UR in Chinese firplantation, and the effects were dependent of the dura-tion following the UR treatment.%以湖南会同地区26年生杉木(Cunninghamia lanceolata)人工林为研究对象,探讨剔除林下植被对土壤呼吸和微

  5. Decreased carbon limitation of litter respiration in a mortality-affected piñon-juniper woodland

    Directory of Open Access Journals (Sweden)

    E. Berryman

    2012-10-01

    Full Text Available Microbial respiration depends on microclimatic variables and carbon (C substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting piñon-juniper ecosystems in Southwestern North America, may affect C substrate availability in several ways; for example, via litterfall pulses and loss of root exudation. To determine piñon mortality effects on C and water limitation of microbial respiration, we applied field amendments (sucrose and water to two piñon-juniper sites in central New Mexico, USA: one with a recent (< 1 yr, experimentally-induced mortality event and a nearby site with live canopy. We monitored the respiration response to water and sucrose applications to the litter surface and to the underlying mineral soil surface, testing the following hypotheses: (1 soil respiration in a piñon-juniper woodland is water- and labile C-limited in both the litter layer and mineral soil; (2 water and sucrose applications increase temperature sensitivity of respiration; (3 the mortality-affected site will show a reduction in C limitation in the litter; (4 the mortality-affected site will show an enhancement of C limitation in the mineral soil. Litter respiration at both sites responded to increased water availability, yet surprisingly, mineral soil respiration was not limited by water. Temperature sensitivity was enhanced by some of the sucrose and water treatments. Consistent with hypothesis 3, C limitation of litter respiration was lower at the recent mortality site compared to the intact canopy site. Results following applications to the mineral soil suggest the presence of abiotic effects of increasing water availability, precluding our ability to measure labile C limitation in soil. Widespread piñon mortality may decrease labile C limitation of litter respiration, at least during the first growing season following mortality.

  6. The diel patterns of soil respiration in four arid California ecosystems: fluxes, sources and hypotheses

    Science.gov (United States)

    Carbone, M.; Trumbore, S.; Winston, G.; Serio, D.

    2007-12-01

    Automated measurements provide the high-resolution information that enables us to analyze potential causes for diel variability in soil respiration. These diel patterns are the complex result of biological and physical processes that determine the production and diffusion of CO2 through the soil. We examined the diel patterns of soil respiration from four arid California ecosystems: (1) a pinon-juniper woodland in at the Burns Pinon Ridge Reserve near Joshua Tree National Park, (2) a cold desert shrub community and (3) a perennial grassland near the city of Bishop in the Owens Valley, and (4) a mixed oak-pine forest at the James Reserve in the San Jacinto Mountains. In addition to automated chamber and environmental measurements at these sites, we used isotopic (14C) partitioning techniques to separate the plant and microbial sources contributing to soil respiration at certain time points. Here we present the diel cycles of soil respiration and environmental variables, the source partitioning results, and hypotheses about what processes determine these diel patterns that both span, and are specific to the studied ecosystems. In these systems dominated by Mediterranean or desert climates, we observed that factors like relative humidity can dominate the diel variations in soil respiration for sites with very dry surface litter. At other sites and times of year, diel variation in soil respiration reflects photosynthetic and VPD influence on root respiration. The combination of automated chamber measurements with isotopes provides information useful for separating the plant and heterotrophic control on diel and seasonal soil respiration fluxes.

  7. Respirators: Supervisors Self-Study #43442

    Energy Technology Data Exchange (ETDEWEB)

    Chochoms, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-20

    This course, Respirators: Supervisors Self-Study (#43442), addresses training requirements for supervisors of respirator wearers as specified by the American National Standard Institute (ANSI) Standard for Respiratory Protection, ANSI Z88.2, and as incorporated by reference in the Department of Energy (DOE) Worker Health and Safety Rule, 10 Code of Federal Regulations (CFR) 851. This course also presents the responsibilities of supervisors of respirator wearers at Los Alamos National Laboratory (LANL).

  8. Effect of Two Improving Measures Based on Returning Phragmites communis Straw on Soil Phy-chemical Properties and Microbial Respiration of the Reclaimed Lands in Chongming Dongtan, China%两种基于芦苇秸秆还田的改良措施对崇明东滩围垦土壤理化性质和微生物呼吸的影响

    Institute of Scientific and Technical Information of China (English)

    陈金海; 李艳丽; 王磊; 张文佺; 王红丽; 付小花; 乐毅全; 管永健; 邱忠虹

    2011-01-01

    在崇明东滩湿地公园设置了3块实验田,研究基于芦苇直接还田(处理Ⅰ)和堆肥后还田(处理Ⅱ)的处理措施对盐碱土壤的改良效应以及对土壤微生物呼吸和植物生长的影响,并通过主成分分析法评价仅考虑传统土壤肥力指标及加和了土壤微生物呼吸和植物生物量等碳收支指标的土壤综合改良效应.结果表明,两种模式都能显著提高土壤的养分.总氮、总磷和总钾均显著高于对照(P<0.05),有机质较对照分别提高10.8%(P=0.053)和10.9%(P=0.052);地上生物量为对照的344%(P=0.000)和167%(P=0.000),但土壤微生物呼吸仅分别较对照提高14%(P=0.085)和43%(P=0.001).主成分分析结果显示仅考虑传统的土壤肥力指标,对照、处理Ⅰ、处理Ⅱ的综合得分分别为-0.641、0.260、0.381,加和土壤微生物呼吸与植物生物量后综合主成分得分为-1.011、0.644、0.367.这表明按传统评价指标,处理Ⅱ是较好的改良模式,但加和了土壤微生物呼吸与植物固碳量等碳收支指标后,处理Ⅰ得分高于处理Ⅱ,因此这是一种相对低碳化的改良模式.%Returning crop straw to land is generally an important measure to soil improvement. Phragmites communis is the most plentiful straw resource in Chongming Island, China. However, few studies on returning Phragmites communis straw and its soil improving effect have been reported. In the experiment, three experimental fields in Chongming Dongtan were selected to study the effect of two improving measures based on returning Phragmites communis straw (measure I:returning Phragmites communis straw plus tillage and fertilization; measure Ⅱ:returning Phragmites communis straw after composting plus tillage and fertilization) on phy-chemical properties and microbial respiration of saline-alkali soil. In addition, the principal components analysis (PCA) was used to evaluate the comprehensive soil improving effect of the two improving measures. The

  9. Effects of plant diversity, functional group composition, and fertilization on soil microbial properties in experimental grassland.

    Directory of Open Access Journals (Sweden)

    Tanja Strecker

    Full Text Available Loss of biodiversity and increased nutrient inputs are two of the most crucial anthropogenic factors driving ecosystem change. Although both received considerable attention in previous studies, information on their interactive effects on ecosystem functioning is scarce. In particular, little is known on how soil biota and their functions are affected by combined changes in plant diversity and fertilization.We investigated the effects of plant diversity, functional community composition, and fertilization on the biomass and respiration of soil microbial communities in a long-term biodiversity experiment in semi-natural grassland (Jena Experiment. Plant species richness enhanced microbial basal respiration and microbial biomass, but did not significantly affect microbial specific respiration. In contrast, the presence of legumes and fertilization significantly decreased microbial specific respiration, without altering microbial biomass. The effect of legumes was superimposed by fertilization as indicated by a significant interaction between the presence of legumes and fertilization. Further, changes in microbial stoichiometry (C-to-N ratio and specific respiration suggest the presence of legumes to reduce N limitation of soil microorganisms and to modify microbial C use efficiency.Our study highlights the role of plant species and functional group diversity as well as interactions between plant community composition and fertilizer application for soil microbial functions. Our results suggest soil microbial stoichiometry to be a powerful indicator of microbial functioning under N limited conditions. Although our results support the notion that plant diversity and fertilizer application independently affect microbial functioning, legume effects on microbial N limitation were superimposed by fertilization, indicating significant interactions between the functional composition of plant communities and nutrient inputs for soil processes.

  10. Plastron Respiration Using Commercial Fabrics

    Directory of Open Access Journals (Sweden)

    Shaun Atherton

    2014-01-01

    Full Text Available A variety of insect and arachnid species are able to remain submerged in water indefinitely using plastron respiration. A plastron is a surface-retained film of air produced by surface morphology that acts as an oxygen-carbon dioxide exchange surface. Many highly water repellent and hydrophobic surfaces when placed in water exhibit a silvery sheen which is characteristic of a plastron. In this article, the hydrophobicity of a range of commercially available water repellent fabrics and polymer membranes is investigated, and how the surface of the materials mimics this mechanism of underwater respiration is demonstrated allowing direct extraction of oxygen from oxygenated water. The coverage of the surface with the plastron air layer was measured using confocal microscopy. A zinc/oxygen cell is used to consume oxygen within containers constructed from the different membranes, and the oxygen consumed by the cell is compared to the change in oxygen concentration as measured by an oxygen probe. By comparing the membranes to an air-tight reference sample, it was found that the membranes facilitated oxygen transfer from the water into the container, with the most successful membrane showing a 1.90:1 ratio between the cell oxygen consumption and the change in concentration within the container.

  11. Spatial uncoupling of biodegradation, soil respiration, and PAH concentration in a creosote contaminated soil.

    Science.gov (United States)

    Bengtsson, Göran; Törneman, Niklas; Yang, Xiuhong

    2010-09-01

    Hotspots and coldspots of concentration and biodegradation of polycyclic aromatic hydrocarbons (PAHs) marginally overlapped at the 0.5-100 m scale in a creosote contaminated soil in southern Sweden, suggesting that concentration and biodegradation had little spatial co-variation. Biodegradation was substantial and its spatial variability considerable and highly irregular, but it had no spatial autocorrelation. The soil concentration of PAHs explained only 20-30% of the variance of their biodegradation. Soil respiration was spatially autocorrelated. The spatial uncoupling between biodegradation and soil respiration seemed to be governed by the aging of PAHs in the soil, since biodegradation of added 13C phenanthrene covaried with both soil respiration and microbial biomass. The latter two were also correlated with high concentrations of phospholipid fatty acids (PLFAs) that are common in gram-negative bacteria. However, several of the hotspots of biodegradation coincided with hotspots for the distribution of a PLFA indicative of fungal biomass.

  12. 42 CFR 84.197 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.197... Cartridge Respirators § 84.197 Respirator containers; minimum requirements. Respirators shall be equipped... commercial designation of the respirator it contains and all appropriate approval labels....

  13. 42 CFR 84.134 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.134... Respirators § 84.134 Respirator containers; minimum requirements. Supplied-air respirators shall be equipped... commercial designation of the respirator it contains, and all appropriate approval labels....

  14. 42 CFR 84.190 - Chemical cartridge respirators: description.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Chemical cartridge respirators: description. 84.190... Cartridge Respirators § 84.190 Chemical cartridge respirators: description. (a) Chemical cartridge respirators including all completely assembled respirators which are designed for use as...

  15. 42 CFR 84.130 - Supplied-air respirators; description.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Supplied-air respirators; description. 84.130... Respirators § 84.130 Supplied-air respirators; description. Supplied-air respirators, including all completely assembled respirators designed for use as respiratory protection during entry into and escape...

  16. Response of δ13C in plant and soil respiration to a water pulse

    Science.gov (United States)

    Salmon, Y.; Buchmann, N.; Barnard, R. L.

    2011-05-01

    Stable carbon isotopes have been used to assess the coupling between changes in environmental conditions and the response of soil or ecosystem respiration, usually by studying the time-lagged response of δ13C of respired CO2 (δ13CR) to changes in photosynthetic carbon isotope discrimination (Δi). However, the lack of a systematic response of δ13CR to environmental changes in field studies stresses the need to better understand the mechanisms to this response. We experimentally created a wide range of carbon allocation and respiration conditions in Fagus sylvatica mesocosms, by growing saplings under different temperatures and girdling combinations. After a period of drought, a water pulse was applied and the short-term responses of δ13C in soil CO2 efflux (δ13CRsoil) and δ13C in aboveground plant respiration (δ13CRabove) were measured, as well as leaf gas exchange rates and soil microbial biomass δ13C responses. Both δ13CRsoil and δ 13CRabove values of all the trees decreased immediately after the water pulse. These responses were not driven by changes in Δi, but rather by a fast release of C stored in roots and shoots. Changes in δ13CRsoil associated with the water pulse were significantly positively correlated with changes in stomatal conductance, showing a strong impact of the plant component on δ13CRsoil. However, three days after the water pulse in girdled trees, changes in δ13CRsoil were related to changes in microbial biomass δ13C, suggesting that changes in the carbon source respired by soil microorganisms also contributed to the response of δ13CRsoil. Our study shows that improving our mechanistic understanding of the responses of δ13CR to changes in environmental conditions requires the understanding of not only the plant's physiological responses, but also the responses of soil microorganisms and of plant-microbial interactions.

  17. SEASONAL CHANGES IN ROOT AND SOIL RESPIRATION OF OZONE-EXPOSED PONDEROSA PINE (PINUS PONDEROSA) GROWN IN DIFFERENT SUBSTRATES

    Science.gov (United States)

    Exposure to(ozone 0-3)has been shown to decrease the allocation of carbon to tree roots. Decreased allocation of carbon to roots might disrupt root metabolism and rhizosphere organisms. The effects of soil type and shoot 0, exposure on below-ground respiration and soil microbial ...

  18. Identification of electrode respiring, hydrocarbonoclastic bacterial strain Stenotrophomonas maltophilia MK2 highlights the untapped potential for environmental bioremediation

    OpenAIRE

    2016-01-01

    Electrode respiring bacteria (ERB) possess a great potential for many biotechnological applications such as microbial electrochemical remediation systems (MERS) because of their exoelectrogenic capabilities to degrade xenobiotic pollutants. Very few ERB have been isolated from MERS, those exhibited a bioremediation potential towards organic contaminants. Here we report once such bacterial strain, Stenotrophomonas maltophilia MK2, a facultative anaerobic bacterium isolated from a hydrocarbon f...

  19. Spatial uncoupling of biodegradation, soil respiration, and PAH concentration in a creosote contaminated soil

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson, Goeran, E-mail: goran.bengtsson@ekol.lu.s [Lund University, Department of Ecology, Soelvegatan 37, SE-223 62 Lund (Sweden); Toerneman, Niklas [Lund University, Department of Ecology, Soelvegatan 37, SE-223 62 Lund (Sweden); Yang Xiuhong [Lund University, Department of Ecology, Soelvegatan 37, SE-223 62 Lund (Sweden); Department of Environmental Science, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2010-09-15

    Hotspots and coldspots of concentration and biodegradation of polycyclic aromatic hydrocarbons (PAHs) marginally overlapped at the 0.5-100 m scale in a creosote contaminated soil in southern Sweden, suggesting that concentration and biodegradation had little spatial co-variation. Biodegradation was substantial and its spatial variability considerable and highly irregular, but it had no spatial autocorrelation. The soil concentration of PAHs explained only 20-30% of the variance of their biodegradation. Soil respiration was spatially autocorrelated. The spatial uncoupling between biodegradation and soil respiration seemed to be governed by the aging of PAHs in the soil, since biodegradation of added {sup 13}C phenanthrene covaried with both soil respiration and microbial biomass. The latter two were also correlated with high concentrations of phospholipid fatty acids (PLFAs) that are common in gram-negative bacteria. However, several of the hotspots of biodegradation coincided with hotspots for the distribution of a PLFA indicative of fungal biomass. - Hotspots of PAH biodegradation in a creosote contaminated soil do not coincide with hotspots of PAH concentration, microbial biomass and respiration.

  20. Respirators: APR Issuer Self Study 33461

    Energy Technology Data Exchange (ETDEWEB)

    Chochoms, Michael [Los Alamos National Laboratory

    2016-07-13

    Respirators: APR Issuer Self-Study (course 33461) is designed to introduce and familiarize employees selected as air-purifying respirator (APR) issuers at Los Alamos National Laboratory (LANL) with the responsibilities, limitations, procedures, and resources for issuing APRs at LANL. The goal is to enable these issuers to consistently provide proper, functioning APRs to authorized users

  1. 78 FR 18535 - Respirator Certification Fees

    Science.gov (United States)

    2013-03-27

    ....\\4\\ A summary of market segmentation, by respirator type, is offered in Table 1, below. \\4\\ Frost... be determined on a case-by-case basis; considerations will include an assessment of the manufacturer... and paint applications and hazardous materials management. Of the U.S. respirator market of...

  2. Mitochondrial respiration is sensitive to cytoarchitectural breakdown.

    Science.gov (United States)

    Kandel, Judith; Angelin, Alessia A; Wallace, Douglas C; Eckmann, David M

    2016-11-07

    An abundance of research suggests that cellular mitochondrial and cytoskeletal disruption are related, but few studies have directly investigated causative connections between the two. We previously demonstrated that inhibiting microtubule and microfilament polymerization affects mitochondrial motility on the whole-cell level in fibroblasts. Since mitochondrial motility can be indicative of mitochondrial function, we now further characterize the effects of these cytoskeletal inhibitors on mitochondrial potential, morphology and respiration. We found that although they did not reduce mitochondrial inner membrane potential, cytoskeletal toxins induced significant decreases in basal mitochondrial respiration. In some cases, basal respiration was only affected after cells were pretreated with the calcium ionophore A23187 in order to stress mitochondrial function. In most cases, mitochondrial morphology remained unaffected, but extreme microfilament depolymerization or combined intermediate doses of microtubule and microfilament toxins resulted in decreased mitochondrial lengths. Interestingly, these two particular exposures did not affect mitochondrial respiration in cells not sensitized with A23187, indicating an interplay between mitochondrial morphology and respiration. In all cases, inducing maximal respiration diminished differences between control and experimental groups, suggesting that reduced basal respiration originates as a largely elective rather than pathological symptom of cytoskeletal impairment. However, viability experiments suggest that even this type of respiration decrease may be associated with cell death.

  3. Evaluation of Microwave Steam Bags for the Decontamination of Filtering Facepiece Respirators

    OpenAIRE

    Fisher, Edward M.; Jessica L Williams; Shaffer, Ronald E.

    2011-01-01

    Reusing filtering facepiece respirators (FFRs) has been suggested as a strategy to conserve available supplies for home and healthcare environments during an influenza pandemic. For reuse to be possible, used FFRs must be decontaminated before redonning to reduce the risk of virus transmission; however, there are no approved methods for FFR decontamination. An effective method must reduce the microbial threat, maintain the function of the FFR, and present no residual chemical hazard. The meth...

  4. Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment

    OpenAIRE

    2016-01-01

    The effects of climate change on soil organic matter-its structure, microbial community, carbon storage, and respiration response-remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climat...

  5. Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment.

    Directory of Open Access Journals (Sweden)

    Ben Bond-Lamberty

    Full Text Available The effects of climate change on soil organic matter-its structure, microbial community, carbon storage, and respiration response-remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5°C monthly maximum air temperature, +50 mm yr-1 precipitation upper site exhibited almost no respiratory response to temperature (Q10 of 1.1, but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. These results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as

  6. Soil Respiration and Bacterial Structure and Function after 17 Years of a Reciprocal Soil Transplant Experiment.

    Science.gov (United States)

    Bond-Lamberty, Ben; Bolton, Harvey; Fansler, Sarah; Heredia-Langner, Alejandro; Liu, Chongxuan; McCue, Lee Ann; Smith, Jeffrey; Bailey, Vanessa

    2016-01-01

    The effects of climate change on soil organic matter-its structure, microbial community, carbon storage, and respiration response-remain uncertain and widely debated. In addition, the effects of climate changes on ecosystem structure and function are often modulated or delayed, meaning that short-term experiments are not sufficient to characterize ecosystem responses. This study capitalized on a long-term reciprocal soil transplant experiment to examine the response of dryland soils to climate change. The two transplant sites were separated by 500 m of elevation on the same mountain slope in eastern Washington state, USA, and had similar plant species and soil types. We resampled the original 1994 soil transplants and controls, measuring CO2 production, temperature response, enzyme activity, and bacterial community structure after 17 years. Over a laboratory incubation of 100 days, reciprocally transplanted soils respired roughly equal cumulative amounts of carbon as non-transplanted controls from the same site. Soils transplanted from the hot, dry, lower site to the cooler and wetter (difference of -5°C monthly maximum air temperature, +50 mm yr-1 precipitation) upper site exhibited almost no respiratory response to temperature (Q10 of 1.1), but soils originally from the upper, cooler site had generally higher respiration rates. The bacterial community structure of transplants did not differ significantly from that of untransplanted controls, however. Slight differences in local climate between the upper and lower Rattlesnake locations, simulated with environmental control chambers during the incubation, thus prompted significant differences in microbial activity, with no observed change to bacterial structure. These results support the idea that environmental shifts can influence soil C through metabolic changes, and suggest that microbial populations responsible for soil heterotrophic respiration may be constrained in surprising ways, even as shorter- and

  7. Effects of Spartina alterniflora invasion on soil respiration in the Yangtze River estuary, China.

    Directory of Open Access Journals (Sweden)

    Naishun Bu

    Full Text Available Many studies have found that plant invasion can enhance soil organic carbon (SOC pools, by increasing net primary production (NPP and/or decreased soil respiration. While most studies have focused on C input, little attention has been paid to plant invasion effects on soil respiration, especially in wetland ecosystems. Our study examined the effects of Spartina alterniflora invasion on soil respiration and C dynamics in the Yangtze River estuary. The estuary was originally occupied by two native plant species: Phragmites australis in the high tide zone and Scirpus mariqueter in the low tide zone. Mean soil respiration rates were 185.8 and 142.3 mg CO2 m(-2 h(-1 in S. alterniflora and P. australis stands in the high tide zone, and 159.7 and 112.0 mg CO2 m(-2 h(-1 in S. alterniflora and S. mariqueter stands in the low tide zone, respectively. Aboveground NPP (ANPP, SOC, and microbial biomass were also significantly higher in the S. alterniflora stands than in the two native plant stands. S. alterniflora invasion did not significantly change soil inorganic carbon or pH. Our results indicated that enhanced ANPP by S. alterniflora exceeded invasion-induced C loss through soil respiration. This suggests that S. alterniflora invasion into the Yangtze River estuary could strengthen the net C sink of wetlands in the context of global climate change.

  8. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Benjamin J. [Department of Physics and Astronomy, University of Southern California, 920 Bloom Walk, Los Angeles, California 90089-0484 (United States); El-Naggar, Mohamed Y., E-mail: mnaggar@usc.edu [Department of Physics and Astronomy, University of Southern California, 920 Bloom Walk, Los Angeles, California 90089-0484 (United States); Molecular and Computational Biology Section, Department of Biological Sciences, University of Southern California, Los Angeles, California 90089-0484 (United States); Department of Chemistry, University of Southern California, Los Angeles, California 90089-0484 (United States)

    2015-06-15

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  9. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces.

    Science.gov (United States)

    Gross, Benjamin J; El-Naggar, Mohamed Y

    2015-06-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  10. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces

    Science.gov (United States)

    Gross, Benjamin J.; El-Naggar, Mohamed Y.

    2015-06-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  11. Soil microbial community of abandoned sand fields.

    Science.gov (United States)

    Elhottová, D; Szili-Kovács, T; Tríska, J

    2002-01-01

    Microbiological evaluation of sandy grassland soils from two different stages of secondary succession on abandoned fields (4 and 8 years old fallow) was carried out as a part of research focused on restoration of semi-natural vegetation communities in Kiskunság National Park in Hungary. There was an apparent total N and organic C enrichment, stimulation of microbial growth and microbial community structure change on fields abandoned by agricultural practice (small family farm) in comparison with native undisturbed grassland. A successional trend of the microbial community was found after 4 and 8 years of fallow-lying soil. It consisted in a shift of r-survival strategy to more efficient C economy, in a decrease of specific respiration and metabolic activity, forced accumulation of storage bacterial compounds and increased fungal distribution. The composition of microbial phospholipid fatty acids mixture of soils abandoned at various times was significantly different.

  12. Data Fusion for Improved Respiration Rate Estimation

    Directory of Open Access Journals (Sweden)

    Gari D. Clifford

    2010-01-01

    Full Text Available We present an application of a modified Kalman-Filter (KF framework for data fusion to the estimation of respiratory rate from multiple physiological sources which is robust to background noise. A novel index of the underlying signal quality of respiratory signals is presented and then used to modify the noise covariance matrix of the KF which discounts the effect of noisy data. The signal quality index, together with the KF innovation sequence, is also used to weight multiple independent estimates of the respiratory rate from independent KFs. The approach is evaluated both on a realistic artificial ECG model (with real additive noise and on real data taken from 30 subjects with overnight polysomnograms, containing ECG, respiration, and peripheral tonometry waveforms from which respiration rates were estimated. Results indicate that our automated voting system can out-perform any individual respiration rate estimation technique at all levels of noise and respiration rates exhibited in our data. We also demonstrate that even the addition of a noisier extra signal leads to an improved estimate using our framework. Moreover, our simulations demonstrate that different ECG respiration extraction techniques have different error profiles with respect to the respiration rate, and therefore a respiration rate-related modification of any fusion algorithm may be appropriate.

  13. Large-scale controls on potential respiration and denitrification in riverine floodplains.

    Science.gov (United States)

    Welti, Nina; Bondar-Kunze, Elisabeth; Singer, Gabriel; Tritthart, Michael; Zechmeister-Boltenstern, Sophie; Hein, Thomas; Pinay, Gilles

    2012-05-01

    Restoration measures of deteriorated river ecosystems generally aim at increasing the spatial heterogeneity and connectivity of these systems in order to increase biodiversity and ecosystem stability. While this is believed to benefit overall ecological integrity, consequences of such restoration projects on biogeochemical processes per se (i.e. ecosystem functioning) in fluvial systems are rarely considered. We address these issues by evaluating the characteristics of surface water connection between side arms and the main river channel in a former braided river section and the role and degree of connectivity (i.e. duration of surface water connection) on the sediment biogeochemistry. We hypothesized that potential respiration and denitrification would be controlled by the degree of hydrological connectivity, which was increased after floodplain restoration. We measured potential microbial respiration (SIR) and denitrification (DEA) and compared a degraded floodplain section of the Danube River with a reconnected and restored floodplain in the same river section. Re-establishing surface water connection altered the controls on sediment microbial respiration and denitrification ultimately impacting potential microbial activities. Meta-variables were created to characterize the effects of hydrology, morphology, and the available carbon and nutrient pools on potential microbial processing. Mantel statistics and path analysis were performed and demonstrate a hierarchy where the effects of hydrology on the available substrates and microbial processing are mediated by the morphology of the floodplain. In addition, these processes are highest in the least connected sites. Surface water connection, mediated by morphology regulates the potential denitrification rate and the ratio of N2O to N2 emissions, demonstrating the effects of restoration in floodplain systems.

  14. Large-scale controls on potential respiration and denitrification in riverine floodplains

    Science.gov (United States)

    Welti, Nina; Bondar-Kunze, Elisabeth; Singer, Gabriel; Tritthart, Michael; Zechmeister-Boltenstern, Sophie; Hein, Thomas; Pinay, Gilles

    2012-01-01

    Restoration measures of deteriorated river ecosystems generally aim at increasing the spatial heterogeneity and connectivity of these systems in order to increase biodiversity and ecosystem stability. While this is believed to benefit overall ecological integrity, consequences of such restoration projects on biogeochemical processes per se (i.e. ecosystem functioning) in fluvial systems are rarely considered. We address these issues by evaluating the characteristics of surface water connection between side arms and the main river channel in a former braided river section and the role and degree of connectivity (i.e. duration of surface water connection) on the sediment biogeochemistry. We hypothesized that potential respiration and denitrification would be controlled by the degree of hydrological connectivity, which was increased after floodplain restoration. We measured potential microbial respiration (SIR) and denitrification (DEA) and compared a degraded floodplain section of the Danube River with a reconnected and restored floodplain in the same river section. Re-establishing surface water connection altered the controls on sediment microbial respiration and denitrification ultimately impacting potential microbial activities. Meta-variables were created to characterize the effects of hydrology, morphology, and the available carbon and nutrient pools on potential microbial processing. Mantel statistics and path analysis were performed and demonstrate a hierarchy where the effects of hydrology on the available substrates and microbial processing are mediated by the morphology of the floodplain. In addition, these processes are highest in the least connected sites. Surface water connection, mediated by morphology regulates the potential denitrification rate and the ratio of N2O to N2 emissions, demonstrating the effects of restoration in floodplain systems. PMID:23565037

  15. An isotope approach based on C-13 pulse-chase labelling vs. the root trenching method to separate heterotrophic and autotrophic respiration in cultivated peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Biasi, C.; Pitkamaki, A. S.; Tavi, N. M.; Koponen, H. T.; Martikainen, P. J. [Univ.of Eastern Finland, Kuopio (Finland). Dept. of Environmental Science], e-mail: christina.biasi@uef.fi

    2012-11-01

    We tested an isotope method based on C-13 pulse-chase labelling for determining the fractional contribution of soil microbial respiration to overall soil respiration in an organic soil (cutaway peatland, eastern Finland), cultivated with the bioenergy crop, reed canary grass. The plants were exposed to CO{sub 2}-13 for five hours and the label was thereafter determined in CO{sub 2} derived from the soil-root system. A two-pool isotope mixing model was used to separate sources of respiration. The isotopic approach showed that a minimum of 50% of the total CO{sub 2} originated from soil-microbial respiration. Even though the method uses undisturbed soil-plant systems, it has limitations concerning the experimental determination of the true isotopic signal of all components contributing to autotrophic respiration. A trenching experiment which was comparatively conducted resulted in a 71% fractional contribution of soil-microbial respiration. This value was likely overestimated. Further studies are needed to evaluate critically the output from these two partitioning approaches. (orig.)

  16. Microbial Life in a Liquid Asphalt Desert

    CERN Document Server

    Schulze-Makuch, Dirk; Antonio, Marina Resendes de Sousa; Ali, Denzil; Hosein, Riad; Song, Young C; Yang, Jinshu; Zaikova, Elena; Beckles, Denise M; Guinan, Edward; Lehto, Harry J; Hallam, Steven J

    2010-01-01

    An active microbiota, reaching up to 10 E+7 cells/g, was found to inhabit a naturally occurring asphalt lake characterized by low water activity and elevated temperature. Geochemical and molecular taxonomic approaches revealed novel and deeply branching microbial assemblages mediating anaerobic hydrocarbon degradation, metal respiration and C1 utilization pathways. These results open a window into the origin and adaptive evolution of microbial life within recalcitrant hydrocarbon matrices, and establish the site as a useful analog for the liquid hydrocarbon environments on Saturn's moon Titan.

  17. Fire vs. Metal: A Laboratory Study Demonstrating Microbial Responses to Soil Disturbances

    Science.gov (United States)

    Stromberger, Mary E.

    2005-01-01

    Incubation studies are traditionally used in soil microbiology laboratory classes to demonstrate microbial respiration and N mineralization-immobilization processes. Sometimes these exercises are done to calculate a N balance in N fertilizer-amended soils. However, examining microbial responses to environmental perturbations would appeal to soil…

  18. Glyphosate toxicity and the effects of long-term vegetation control on soil microbial communities

    Science.gov (United States)

    Matt D. Busse; Alice W. Ratcliff; Carol J. Stestak; Robert F. Powers

    2001-01-01

    We assessed the direct and indirect effect of the herbicide glyphosate on soil microbial communities from soil bioassays at glyphosate concentrations up to 100-fold greater than expected following a single field application. Indirect effects on microbial biomass, respiration, and metabolic diversity (Biolog and catabolic response profile) were compared seasonally after...

  19. The effect of gender and respirator brand on the association of respirator fit with facial dimensions.

    Science.gov (United States)

    Oestenstad, R Kent; Elliott, Leshan J; Beasley, T Mark

    2007-12-01

    This study examined the association of facial dimensions with respirator fit considering the effect of gender and respirator brand. Forty-one subjects (20 white females and 21 white males) participated in the study. Each subject was measured for 12 facial dimensions using anthropometric sliding and spreading calipers and a steel measuring tape. Three quantitative fit tests were conducted with the same subject wearing one size of three different brands of half-mask respirators resulting in a total of nine fit tests. Linear mixed model analysis was used to model respirator fit as a function of gender and respirator brand while controlling for facial dimensions. Results indicated that the gender by respirator brand interaction was not statistically significant (p = 0.794), and there was no significant difference in respirator fit between males and females (p = 0.356). There was a significant difference in respirator fit among respirator brands (p brand, six separate linear mixed models were fit to assess which facial dimensions most strongly relate to respirator fit using a "one variable at a step" backward elimination procedure. None of the 12 facial dimensions were significantly associated with respirator fit in all six models. However, bigonial breadth and menton-nasion length were significantly associated with respirator fit in five of the six models, and biectoorbitale breadth, bizygomatic breadth, and lip width were significantly associated with respirator fit in four of the six models. Although this study resulted in significant findings related to the correlation of respirator fit with menton-nasion length and lip width (the dimensions currently used to define the half-mask respirator test panel), other facial dimensions were also shown to be significantly associated with respirator fit. Based on these findings and findings from previous studies, it is suggested that other facial dimensions including bigonial breadth, biectoorbitale breadth, and bizygomatic

  20. Aerobic respiration in the Archaean?

    Science.gov (United States)

    Towe, K M

    1990-11-01

    The Earth's atmosphere during the Archaean era (3,800-2,500 Myr ago) is generally thought to have been anoxic, with the partial pressure of atmospheric oxygen about 10(-12) times the present value. In the absence of aerobic consumption of oxygen produced by photosynthesis in the ocean, the major sink for this oxygen would have been oxidation of dissolved Fe(II). Atmospheric oxygen would also be removed by the oxidation of biogenic methane. But even very low estimates of global primary productivity, obtained from the amounts of organic carbon preserved in Archaean rocks, seem to require the sedimentation of an unrealistically large amount of iron and the oxidation of too much methane if global anoxia was to be maintained. I therefore suggest that aerobic respiration must have developed early in the Archaean to prevent a build-up of atmospheric oxygen before the Proterozoic. An atmosphere that contained a low (0.2-0.4%) but stable proportion of oxygen is required.

  1. Ecogenomics of microbial communities in bioremediation of chlorinated contaminated sites

    Directory of Open Access Journals (Sweden)

    Farai eMaphosa

    2012-10-01

    Full Text Available Organohalide compounds such as chloroethenes, chloroethanes and polychlorinated benzenes are among the most significant pollutants in the world. These compounds are often found in contamination plumes with other pollutants such as solvents, pesticides and petroleum derivatives. Microbial bioremediation of contaminated sites, has become commonplace whereby key processes involved in bioremediation include anaerobic degradation and transformation of these organohalides by organohalide respiring bacteria and also via hydrolytic, oxygenic and reductive mechanisms by aerobic bacteria. Microbial ecogenomics has enabled us to not only study the microbiology involved in these complex processes but also develop tools to better monitor and assess these sites during bioremediation. Microbial ecogenomics have capitalized on recent advances in high-throughput and -output genomics technologies in combination with microbial physiology studies to address these complex bioremediation problems at a system level. Advances in environmental metagenomics, transcriptomics and proteomics have provided insights into key genes and their regulation in the environment. They have also given us clues into microbial community structures, dynamics and functions at contaminated sites. These techniques have not only aided us in understanding the lifestyles of common organohalide respirers, for example Dehalococcoides, Dehalobacter and Desulfitobacterium, but also provided insights into novel and yet uncultured microorganisms found in organohalide respiring consortia. In this paper we look at how ecogenomic studies have aided us to understand the microbial structures and functions in response to environmental stimuli such as the presence of chlorinated pollutants.

  2. Religious competence as cultural competence

    Science.gov (United States)

    2012-01-01

    Definitions of cultural competence often refer to the need to be aware and attentive to the religious and spiritual needs and orientations of patients. However, the institution of psychiatry maintains an ambivalent attitude to the incorporation of religion and spirituality into psychiatric practice. This is despite the fact that many patients, especially those from underserved and underprivileged minority backgrounds, are devotedly religious and find much solace and support in their religiosity. I use the case of mental health of African Americans as an extended example to support the argument that psychiatric services must become more closely attuned to religious matters. I suggest ways in which this can be achieved. Attention to religion can aid in the development of culturally competent and accessible services, which in turn, may increase engagement and service satisfaction among religious populations. PMID:22421686

  3. Respiration-to-DNA ratio reflects physiological state of microorganisms in root-free and rhizosphere soil

    Science.gov (United States)

    Blagodatskaya, E.; Blagodatsky, S.; Kuzyakov, Y.

    2009-04-01

    The double-stranded DNA (dsDNA) content in soil can serve as a measure of microbial biomass under near steady-state conditions and quantitatively reflect the exponential microbial growth initiated by substrate addition. The yield of respired CO2 per microbial biomass unit (expressed as DNA content) could be a valuable physiological indicator reflecting state of soil microbial community. Therefore, investigations combining both analyses of DNA content and respiration of soil microorganisms under steady-state and during periods of rapid growth are needed. We studied the relationship between CO2 evolution and microbial dsDNA content in native and glucose-amended samples of root-free and rhizosphere soil under Beta vulgaris (Cambisol, loamy sand from the field experiment of the Institute of Agroecology FAL, Braunschweig, Germany). Quantity of dsDNA was determined by direct DNA isolation from soil with mechanic and enzymatic disruption of microbial cell walls with following spectrofluorimetric detection with PicoGreen (Blagodatskaya et al., 2003). Microbial biomass and the kinetic parameters of microbial growth were estimated by dynamics of the CO2 emission from soil amended with glucose and nutrients (Blagodatsky et al., 2000). The CO2 production rate was measured hourly at 22оС using an automated infrared-gas analyzer system. The overall increase in microbial biomass, DNA content, maximal specific growth rate and therefore, in the fraction of microorganisms with r-strategy were observed in rhizosphere as compared to bulk soil. The rhizosphere effect for microbial respiration, biomass and specific growth rate was more pronounced for plots with half-rate of N fertilizer compared to full N addition. The DNA content was significantly lower in bulk compared to rhizosphere soil both before and during microbial growth initiated by glucose amendment. Addition of glucose to the soil strongly increased the amount of CO2 respired per DNA unit. Without substrate addition the

  4. Arbuscular mycorrhiza fungi mediate soil respiration response to climate change in California grasslands

    Science.gov (United States)

    Estruch, Carme; Mcfarland, Jack; Haw, Monica P.; Schulz, Marjorie S.; Pugnaire, Francisco I.; Waldrop, Mark P.

    2017-04-01

    California grasslands store ca. 100 Tg of soil organic carbon (SOC) and almost 40% of those ecosystems are prone to land use changes. The fate of these carbon pools will largely depend on how the main components of soil respiration - i.e., roots, mycorrhiza, and 'bulk soil' communities- respond to such changes. In order to determine the sensitivity to environmental drivers we set up an experiment to address the effect of plant community composition, soil age and warming on soil respiration rate during the 2014-2015 winter. We tested differences among microbial, fungal and root respiration using an exclusion technique to assess the effect of plant community (open grasslands vs oak woodland) in two field sites differing in soil properties as nutrient content, related to geologic soil age (92 and 137 kyr). We also used open top chambers (OTC) to simulate global change effects on grasslands. Our results showed that arbuscular mycorrhizal fungi were the main drivers of differences recorded between soils of different age, and that those differences were linked to nutrient availability. Bulk soil respiration was more sensitive to environmental variation than mycorrhizal or root respiration, indicating that the presence of mycorrhizae and roots can regulate the capacity of CO2 emission to the atmosphere. Soil age affected CO2 flux from grasslands but not under oak canopies, likely due to the high concentration of SOM in oak canopies which moderated any affect of soil mineralogy on nutrient availability. Overall our study shows that the ability of grasslands to mitigate CO2 emissions depends on interactions between vegetation and their rhizosphere on soil microbial communities.

  5. Probing soil respiration process of grasslands

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ Soil respiration, which is primarily the only output approach for CO2 exchanges in soils between the global terrestrial ecosystem and the atmosphere,exerts a direct influence on the speed of carbon turnover rate of the soil.

  6. Microgradients of microbial oxygen consumption in a barley rhizosphere model system

    DEFF Research Database (Denmark)

    Højberg, Ole; Sorensen, J.

    1993-01-01

    was in turn 10 to 30 times higher than that in the rhizoplane. Both microbial respiration and oxygen uptake by the root varied between different roots. This was probably due to a between-root variation of the exudation rate for easily degradable carbon compounds supporting the microbial oxygen consumption.......A microelectrode technique was used to map the radial distribution of oxygen concentrations and oxygen consumption rates around single roots of 7- day-old barley seedlings. The seedlings were grown in gel-stabilized medium containing a nutrient solution, a soil extract, and an inert polymer. Oxygen...... consumption by microbial respiration in the rhizosphere (30 mm from the root) was determined by using Fick's laws of diffusion and an analytical approach with curve fitting to measured microprofiles of oxygen concentration. A marked increase of microbial respiration...

  7. Effect of Music on Emotions and Respiration

    OpenAIRE

    NOGUCHI Kengo:筆頭著者; MASAOKA Yuri; SATOH Kanako; Kato, Nobumasa; Homma, Ikuo

    2012-01-01

    In the present study we investigated whether the emotional state induced by music can change respiratory rate (RR), tidal volume (VT), minute ventilation (VE), and end-tidal CO2concentration (ETCO2). In a pioneering study investigating the effect of music on respiration, the music of Stockhausen and Chopin was used. In the present study, we examined the effects of the same musical stimuli used in that study on respiration. Each stimulus (Stockhausen, Chopin, and silence) was delivered for 30 ...

  8. [Effects of Tillage on Soil Respiration and Root Respiration Under Rain-Fed Summer Corn Field].

    Science.gov (United States)

    Lu, Xing-li; Liao, Yun-cheng

    2015-06-01

    To explore the effects of different tillage systems on soil respiration and root respiration under rain-fed condition. Based on a short-term experiment, this paper investigated soil respiration in summer corn growth season under four tillage treatments including subsoiling tillage (ST), no tillage (NT), rotary tillage (RT) and moldboard plow tillage (CT). The contribution of root respiration using root exclusion method was also discussed. The results showed that soil respiration rate presented a single peak trend under four tillage methods during the summer corn growing season, and the maximum value was recorded at the heading stage. The trends of soil respiration were as follows: heading stage > flowering stage > grain filling stage > maturity stage > jointing stage > seedling stage. The trends of soil respiration under different tillage systems were as follows: CT > ST > RT > NT. There was a significant correlation between soil respiration rate and soil temperatures (P tillage systems. Therefore, root exclusion method could be used to study the contribution of crop growth to carbon emission, to compare effects of different tillage systems on the contribution of root respiration provides the bases for selecting the measures to slow down the decomposition of soil carbon.

  9. Impacts of chemical gradients on microbial community structure

    DEFF Research Database (Denmark)

    Chen, Jianwei; Hanke, Anna; Tegetmeyer, Halina E

    2017-01-01

    Succession of redox processes is sometimes assumed to define a basic microbial community structure for ecosystems with oxygen gradients. In this paradigm, aerobic respiration, denitrification, fermentation and sulfate reduction proceed in a thermodynamically determined order, known as the 'redox ...... Journal advance online publication, 17 January 2017; doi:10.1038/ismej.2016.175....

  10. Eutrophication, microbial-sulfate reduction and mass extinctions

    DEFF Research Database (Denmark)

    Schobben, Martin; Stebbins, Alan; Ghaderi, Abbas

    2016-01-01

    to the Earth system, notably, the biogeochemical sulfur and carbon cycle. This climate warming feedback produces large-scale eutrophication on the continental shelf, which, in turn, expands oxygen minimum zones by increased respiration, which can turn to a sulfidic state by increased microbial-sulfate...

  11. 42 CFR 84.191 - Chemical cartridge respirators; required components.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Chemical cartridge respirators; required components... Chemical Cartridge Respirators § 84.191 Chemical cartridge respirators; required components. (a) Each chemical cartridge respirator described in § 84.190 shall, where its design requires, contain the...

  12. 78 FR 18601 - Respirator Certification Fees; Public Meeting

    Science.gov (United States)

    2013-03-27

    ... HUMAN SERVICES Centers for Disease Control and Prevention Respirator Certification Fees; Public Meeting... stakeholders to present information the impact of an increase on respirator fees on individual respirator manufacturers, the respirator market, or on those industries that rely on NIOSH approved respiratory...

  13. 42 CFR 84.174 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84.174... Air-Purifying Particulate Respirators § 84.174 Respirator containers; minimum requirements. (a) Except as provided in paragraph (b) of this section each respirator shall be equipped with a...

  14. 42 CFR 84.250 - Vinyl chloride respirators; description.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Vinyl chloride respirators; description. 84.250... Respirators § 84.250 Vinyl chloride respirators; description. Vinyl chloride respirators, including all... escape from vinyl chloride atmospheres containing adequate oxygen to support life, are...

  15. Characterizing the snorkeling respiration and growth of Shewanella decolorationis S12.

    Science.gov (United States)

    Yang, Yonggang; Guo, Jun; Sun, Guoping; Xu, Meiying

    2013-01-01

    Microbial electrochemical snorkel (MES) reactor is a simplified bioreactor based on microbial fuel cells (MFCs) and has been suggested to be a promising approach to solve many environmental problems. However, the microbial processes in MES reactors have not yet been characterized. This study shows that Shewanella decolorationis S12 can use the conductive snorkel as direct electron acceptor for respiration and growth. Similar with current-generating biofilms, cellular viability in MES biofilms decreased with the distance from snorkel. MES reactors showed more rapid cell growth and substrate consumption than MFCs. Although the biomass density of MES biofilm was higher than that of anode biofilms, the current-generating capacity and electrochemical activity of MES biofilm were lower, which could be attributed to the lower cytochrome c expression in MES biofilm caused by the higher redox potential of MES. These microbiological and electrochemical properties are essential for the further development of MES reactors.

  16. Contribution of root to soil respiration and carbon balance in disturbed and undisturbed grassland communities, northeast China

    Indian Academy of Sciences (India)

    Wei Wang; Jixun Guo; Takehisa Oikawa

    2007-03-01

    Changes in the composition of plant species induced by grassland degradation may alter soil respiration rates and decrease carbon sequestration; however, few studies in this area have been conducted. We used net primary productivity (NPP), microbial biomass carbon (MBC), and soil organic carbon (SOC) to examine the changes in soil respiration and carbon balance in two Chinese temperate grassland communities dominated by Leymus chinensis (undisturbed community; Community 1) and Puccinellia tenuiflora (degraded community; Community 2), respectively. Soil respiration varied from 2.5 to 11.9 g CO2 m-2 d-1 and from 1.5 to 9.3 g CO2 m-2 d-1, and the contribution of root respiration to total soil respiration from 38% to 76% and from 25% to 72% in Communities 1 and 2, respectively. During the growing season (May–September), soil respiration, shoot biomass, live root biomass, MBC and SOC in Community 2 decreased by 28%, 39%, 45%, 55% and 29%, respectively, compared to those in Community 1. The considerably lower net ecosystem productivity in Community 2 than in Community 1 (104.56 vs. 224.73 g C m-2 yr-1) suggests that the degradation has significantly decreased carbon sequestration of the ecosystems.

  17. Response of soil respiration to acid rain in forests of different maturity in southern China.

    Science.gov (United States)

    Liang, Guohua; Liu, Xingzhao; Chen, Xiaomei; Qiu, Qingyan; Zhang, Deqiang; Chu, Guowei; Liu, Juxiu; Liu, Shizhong; Zhou, Guoyi

    2013-01-01

    The response of soil respiration to acid rain in forests, especially in forests of different maturity, is poorly understood in southern China despite the fact that acid rain has become a serious environmental threat in this region in recent years. Here, we investigated this issue in three subtropical forests of different maturity [i.e. a young pine forest (PF), a transitional mixed conifer and broadleaf forest (MF) and an old-growth broadleaved forest (BF)] in southern China. Soil respiration was measured over two years under four simulated acid rain (SAR) treatments (CK, the local lake water, pH 4.5; T1, water pH 4.0; T2, water pH 3.5; and T3, water pH 3.0). Results indicated that SAR did not significantly affect soil respiration in the PF, whereas it significantly reduced soil respiration in the MF and the BF. The depressed effects on both forests occurred mostly in the warm-wet seasons and were correlated with a decrease in soil microbial activity and in fine root biomass caused by soil acidification under SAR. The sensitivity of the response of soil respiration to SAR showed an increasing trend with the progressive maturity of the three forests, which may result from their differences in acid buffering ability in soil and in litter layer. These results indicated that the depressed effect of acid rain on soil respiration in southern China may be more pronounced in the future in light of the projected change in forest maturity. However, due to the nature of this field study with chronosequence design and the related pseudoreplication for forest types, this inference should be read with caution. Further studies are needed to draw rigorous conclusions regarding the response differences among forests of different maturity using replicated forest types.

  18. Response of soil respiration to acid rain in forests of different maturity in southern China.

    Directory of Open Access Journals (Sweden)

    Guohua Liang

    Full Text Available The response of soil respiration to acid rain in forests, especially in forests of different maturity, is poorly understood in southern China despite the fact that acid rain has become a serious environmental threat in this region in recent years. Here, we investigated this issue in three subtropical forests of different maturity [i.e. a young pine forest (PF, a transitional mixed conifer and broadleaf forest (MF and an old-growth broadleaved forest (BF] in southern China. Soil respiration was measured over two years under four simulated acid rain (SAR treatments (CK, the local lake water, pH 4.5; T1, water pH 4.0; T2, water pH 3.5; and T3, water pH 3.0. Results indicated that SAR did not significantly affect soil respiration in the PF, whereas it significantly reduced soil respiration in the MF and the BF. The depressed effects on both forests occurred mostly in the warm-wet seasons and were correlated with a decrease in soil microbial activity and in fine root biomass caused by soil acidification under SAR. The sensitivity of the response of soil respiration to SAR showed an increasing trend with the progressive maturity of the three forests, which may result from their differences in acid buffering ability in soil and in litter layer. These results indicated that the depressed effect of acid rain on soil respiration in southern China may be more pronounced in the future in light of the projected change in forest maturity. However, due to the nature of this field study with chronosequence design and the related pseudoreplication for forest types, this inference should be read with caution. Further studies are needed to draw rigorous conclusions regarding the response differences among forests of different maturity using replicated forest types.

  19. Substrate-induced changes in microbial community-level physiological profiles and their application to discriminate soil microbial communities

    Institute of Scientific and Technical Information of China (English)

    CHEN Jian; XIE Huijun; ZHUANG Xuliang; ZHUANG Guoqiang; BAI Zhihui; ZHANG Hongxun

    2008-01-01

    The addition of simple substrates could affect the microbial respiration in soils.This substrate-induced respiration is widely used to estimate the soil microbial biomass,but little attention has been paid to its influence on the changes of community-level physiological profiles.In this study,the process of microbial communities responding to the added substrate using sole-carbon-source utilization (BIOLOG) was investigated.BIOLOG is biased toward fast-growing bacteria;this advantage Was taken to detect the prompt response of the active microbial communities to the added substrate.Four soil samples from agricultural fields adjacent to heavy metal mines were amended with L-arginine,citric acid,or D-glucose.Substrate amendments could,generally,not only increase the metabolic activity of the microbial communities,but also change the metabolic diverse patterns compared with no-substrate contr01.By tracking the process,it was found that the variance between substrate-induced treatment and control fluctuated greatly during the incubation course,and the influences of these three substrates were difierent.In addition,the application of these induced changes to discriminate soil microbial communities was tested.T1le distance among all samples was greatly increased.which further showed the functional variance among microbial communities in soils.This Can be very useful in the discrimination of microbial communities eveB with high similarity.

  20. A cost-effective and field-ready potentiostat that poises subsurface electrodes to monitor bacterial respiration.

    Science.gov (United States)

    Friedman, Elliot S; Rosenbaum, Miriam A; Lee, Alexander W; Lipson, David A; Land, Bruce R; Angenent, Largus T

    2012-02-15

    Here, we present the proof-of-concept for a subsurface bioelectrochemical system (BES)-based biosensor capable of monitoring microbial respiration that occurs through exocellular electron transfer. This system includes our open-source design of a three-channel microcontroller-unit (MCU)-based potentiostat that is capable of chronoamperometry, which laboratory tests showed to be accurate within 0.95 ± 0.58% (95% Confidence Limit) of a commercial potentiostat. The potentiostat design is freely available online: http://angenent.bee.cornell.edu/potentiostat.html. This robust and field-ready potentiostat, which can withstand temperatures of -30°C, can be manufactured at relatively low cost ($600), thus, allowing for en-masse deployment at field sites. The MCU-based potentiostat was integrated with electrodes and a solar panel-based power system, and deployed as a biosensor to monitor microbial respiration in drained thaw lake basins outside Barrow, AK. At three different depths, the working electrode of a microbial three-electrode system (M3C) was maintained at potentials corresponding to the microbial reduction of iron(III) compounds and humic acids. Thereby, the working electrode mimics these compounds and is used by certain microbes as an electron acceptor. The sensors revealed daily cycles in microbial respiration. In the medium- and deep-depth electrodes the onset of these cycles followed a considerable increase in overall activity that corresponded to those soils reaching temperatures conducive to microbial activity as the summer thaw progressed. The BES biosensor is a valuable tool for studying microbial activity in situ in remote environments, and the cost-efficient design of the potentiostat allows for wide-scale use in remote areas. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Soil Carbon Inputs and Ecosystem Respiration: a Field Priming Experiment in Arctic Coastal Tundra

    Science.gov (United States)

    Vaughn, L. S.; Zhu, B.; Bimueller, C.; Curtis, J. B.; Chafe, O.; Bill, M.; Abramoff, R. Z.; Torn, M. S.

    2016-12-01

    In Arctic ecosystems, climate change is expected to influence soil carbon stocks through changes in both plant carbon inputs and organic matter decomposition. This study addresses the potential for a priming effect, an interaction between these changes in which root-derived carbon inputs alter SOM decomposition rates via microbial biomass increases, co-metabolism of substrates, induced nitrogen limitation, or other possible mechanisms. The priming effect has been observed in numerous laboratory and greenhouse experiments, and is increasingly included in ecosystem models. Few studies, however, have evaluated the priming effect with in situ field manipulations. In a two-year field experiment in Barrow, Alaska, we tested for a priming effect under natural environmental variability. In September 2014 and August 2015, we added 6.1g of 13C-labeled glucose to 25cm diameter mesocosms, 15cm below the soil surface in the mineral soil layer. Over the following month, we quantified effects on the rate and temperature sensitivity of native (non-glucose) ecosystem respiration and GPP. Following the 2014 treatment, soil samples were collected at 1 and 3 weeks for microbial biomass carbon and 13C/12C analysis, and ion exchange membranes were buried for one week to assess nitrate and ammonium availability. In contrast with many laboratory incubation studies using soils from a broad range of ecosystems, we observed no significant priming effect. In spite of a clear signal of 13C-glucose decomposition in respired CO2 and microbial biomass, we detected no treatment effect on background ecosystem respiration or total microbial biomass carbon. Our findings suggest that glucose taken up by microbes was not used for production of additional SOM-decomposing enzymes, possibly due to stoichiometric limitations on enzyme production. To best inform models representing complex and dynamic ecosystems, this study calls for further research relating theory, laboratory findings, and field

  2. Alterations in soil microbial community composition and biomass following agricultural land use change

    Science.gov (United States)

    Zhang, Qian; Wu, Junjun; Yang, Fan; Lei, Yao; Zhang, Quanfa; Cheng, Xiaoli

    2016-11-01

    The effect of agricultural land use change on soil microbial community composition and biomass remains a widely debated topic. Here, we investigated soil microbial community composition and biomass [e.g., bacteria (B), fungi (F), Arbuscular mycorrhizal fungi (AMF) and Actinomycete (ACT)] using phospholipid fatty acids (PLFAs) analysis, and basal microbial respiration in afforested, cropland and adjacent uncultivated soils in central China. We also investigated soil organic carbon and nitrogen (SOC and SON), labile carbon and nitrogen (LC and LN), recalcitrant carbon and nitrogen (RC and RN), pH, moisture, and temperature. Afforestation averaged higher microbial PLFA biomass compared with cropland and uncultivated soils with higher values in top soils than deep soils. The microbial PLFA biomass was strongly correlated with SON and LC. Higher SOC, SON, LC, LN, moisture and lower pH in afforested soils could be explained approximately 87.3% of total variation of higher total PLFAs. Afforestation also enhanced the F: B ratios compared with cropland. The basal microbial respiration was higher while the basal microbial respiration on a per-unit-PLFA basis was lower in afforested land than adjacent cropland and uncultivated land, suggesting afforestation may increase soil C utilization efficiency and decrease respiration loss in afforested soils.

  3. Plant Respiration and Climate Change Effects

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, D.

    2002-04-01

    Plant respiration is one of the key processes in terms of an understanding of plant growth and functioning in a future climate. Short- and long-term effects of temperature and CO{sub 2} on plant respiration were investigated in a number of plant species. The experiments tested effects of either temperature and/or CO{sub 2} from the level of individual respiratory enzymes, isolated mitochondria, whole-tissue, and up to the whole canopy level. The short-term effects of elevated atmospheric CO{sub 2} on plant respiration appeared to be less than suggested so far in the literature. This was true both at the tissue level and for intact mitochondria. Respiratory enzymes can, however, be affected already at low CO{sub 2}. These effects did not manifest itself at the tissue level, though, due to low degrees of control on the whole respiratory process exerted by the particular enzymes. Plant respiration on the other hand was affected by long-term growth at elevated atmospheric CO{sub 2}. The findings of the reduced plant respiration at the leaf level were consistent with the literature and potential causes are discussed. Short-term effects of temperature on plant respiration were demonstrated to be dependent on the actual measurement temperature. Further, it is shown that mitochondrial leaf respiration in darkness and light differ substantially in the temperature sensitivity with the former being the far most sensitive. This has implications for modelling CO{sub 2} exchange between vegetation and atmosphere as demonstrated here, since this has so far been neglected. Long-term effects of temperature resulted in respiratory acclimation in a number of species. Respiratory acclimation appeared not to occur to any one single type of growth temperature. The implications of this finding in combination with the timing of acclimation are discussed for modelling respiratory CO{sub 2} release. (au)

  4. Functional activity of soil microbial communities in post-fire pine stands of Tolyatti, Samara oblast

    Science.gov (United States)

    Maksimova, E. Yu.; Kudinova, A. G.; Abakumov, E. V.

    2017-02-01

    The state of microbial communities in gray-humus soils (Eutric Fluvic Arenosols (Ochric)) of pine stands in the city of Tolyatti after forest fires of 2010 is analyzed. It is shown that fires exert negative effects on the structure and metabolic activity of microbial communities in the postpyrogenic soils. The content of the carbon of microbial biomass and the intensity of microbial respiration in the upper organic horizons of the post-fire plots decrease by 6.5 and 3.4 times, respectively, in comparison with those in the soils of background plots. However, the fire has not affected the studied microbiological parameters of the soils at the depths of more than 10 cm. The maximum content of the carbon of microbial biomass carbon and the maximum intensity of microbial respiration have been found in the subsurface AY2 and AC horizons two-three years the fire. An increase in the microbial metabolic quotient (the ratio of soil respiration to microbial biomass) attests to the disturbance of the ecophysiological state of soil microbial communities after the pyrogenic impact.

  5. Flat laminated microbial mat communities

    Science.gov (United States)

    Franks, Jonathan; Stolz, John F.

    2009-10-01

    Flat laminated microbial mats are complex microbial ecosystems that inhabit a wide range of environments (e.g., caves, iron springs, thermal springs and pools, salt marshes, hypersaline ponds and lagoons, methane and petroleum seeps, sea mounts, deep sea vents, arctic dry valleys). Their community structure is defined by physical (e.g., light quantity and quality, temperature, density and pressure) and chemical (e.g., oxygen, oxidation/reduction potential, salinity, pH, available electron acceptors and donors, chemical species) parameters as well as species interactions. The main primary producers may be photoautotrophs (e.g., cyanobacteria, purple phototrophs, green phototrophs) or chemolithoautophs (e.g., colorless sulfur oxidizing bacteria). Anaerobic phototrophy may predominate in organic rich environments that support high rates of respiration. These communities are dynamic systems exhibiting both spatial and temporal heterogeneity. They are characterized by steep gradients with microenvironments on the submillimeter scale. Diel oscillations in the physical-chemical profile (e.g., oxygen, hydrogen sulfide, pH) and species distribution are typical for phototroph-dominated communities. Flat laminated microbial mats are often sites of robust biogeochemical cycling. In addition to well-established modes of metabolism for phototrophy (oxygenic and non-oxygenic), respiration (both aerobic and anaerobic), and fermentation, novel energetic pathways have been discovered (e.g., nitrate reduction couple to the oxidation of ammonia, sulfur, or arsenite). The application of culture-independent techniques (e.g., 16S rRNA clonal libraries, metagenomics), continue to expand our understanding of species composition and metabolic functions of these complex ecosystems.

  6. Plankton respiration in the Eastern Atlantic Ocean

    Science.gov (United States)

    Robinson, Carol; Serret, Pablo; Tilstone, Gavin; Teira, Eva; Zubkov, Mikhail V.; Rees, Andrew P.; Woodward, E. Malcolm S.

    2002-05-01

    Concurrent measurements of dark community respiration (DCR), gross production (GP), size fractionated primary production ( 14C PP), nitrogen uptake, nutrients, chlorophyll a concentration, and heterotrophic and autotrophic bacterial abundance were collected from the upper 200 m of a latitudinal (32°S-48°N) transect in the Eastern Atlantic Ocean during May/June 1998. The mean mixed layer respiration rate was 2.5±2.1 mmol O 2 m -3 d -1 ( n=119) for the whole transect, 2.2±1.1 mmol O 2 m -3 d -1 ( n=32) in areas where chlorophyll a was dissolved oxygen consumption, was 0.8 ( n=11). At the time of the study, plankton community respiration exceeded GP in the picoautotroph dominated oligotrophic regions (Eastern Tropical Atlantic [15.5°S-14.2°N] and North Atlantic Subtropical Gyre [21.5-42.5°N]), which amounted to 50% of the stations sampled along the 12,100 km transect. These regions also exhibited high heterotrophic: autotrophic biomass ratios, higher turnover rates of phytoplankton than of bacteria and low f ratios. However, the carbon supply mechanisms required to sustain the rates of respiration higher than GP could not be fully quantified. Future research should aim to determine the temporal balance of respiration and GP together with substrate supply mechanisms in these ocean regions.

  7. Improving respiration measurements with gas exchange analyzers.

    Science.gov (United States)

    Montero, R; Ribas-Carbó, M; Del Saz, N F; El Aou-Ouad, H; Berry, J A; Flexas, J; Bota, J

    2016-12-01

    Dark respiration measurements with open-flow gas exchange analyzers are often questioned for their low accuracy as their low values often reach the precision limit of the instrument. Respiration was measured in five species, two hypostomatous (Vitis Vinifera L. and Acanthus mollis) and three amphistomatous, one with similar amount of stomata in both sides (Eucalyptus citriodora) and two with different stomata density (Brassica oleracea and Vicia faba). CO2 differential (ΔCO2) increased two-fold with no change in apparent Rd, when the two leaves with higher stomatal density faced outside. These results showed a clear effect of the position of stomata on ΔCO2. Therefore, it can be concluded that leaf position is important to guarantee the improvement of respiration measurements increasing ΔCO2 without affecting the respiration results by leaf or mass units. This method will help to increase the accuracy of leaf respiration measurements using gas exchange analyzers. Copyright © 2016 Elsevier GmbH. All rights reserved.

  8. Respiration rate in human pituitary tumor explants.

    Science.gov (United States)

    Anniko, M; Bagger-Sjöbäck, D; Hultborn, R

    1982-01-01

    Studies on the respiration rate of human pituitary tumor tissue have so far been lacking in the literature. This study presents the results from four adenomas causing acromegaly, all with different clinical degrees of the disease. Determination of oxygen uptake was performed in vitro with a spectrophotorespirometric system. Pieces of the tumors were explanted to an organ culture system with a high degree of stability. The secretion rate of growth hormone (GH) and prolactin (PRL) was determined. After 4-8 days in vitro, specimens were analyzed for respiration rate. This was approximately 1-1.5 microliters O2/h/micrograms dry weight. The activity of the pituitary tumor tissue was characterized by both the hormone secretion rate and the respiration rate. Particularly active foci were found to occur in the adenoma tissue. Depending on the individual tumor, the GH secretion rate was approximately 0.1-100 pmol/micrograms dry weight/h and PRL secretion rate approximately 0.4-18 micrograms/micrograms dry weight/h. The respiration rate--as is also the hormone secretion rate--is dependent on the time in vitro prior to analysis. The respiration rate in individual tumors is a parameter which does not reflect GH or PRL serum levels or clinical activity of the disease.

  9. THE RELATION OF PHOTOSYNTHESIS TO RESPIRATION

    Energy Technology Data Exchange (ETDEWEB)

    Weigl, J.W.; Warrington, P.M.; Calvin, M.

    1950-07-20

    The gas exchange by barley leaves of oxygen, carbon dioxide, and added radiocarbon dioxide has been measured in a closed system, with the following results: 1. Carbon dioxide follows different but not necessarily independent paths in photosynthesis and light respiration. 2. The carbon of newly formed photosynthetic intermediates is not available for respiration while the light is on, but becomes immediately respirable in the dark, The enhancement of dark respiration after a light period is largely due to built-up ''photosynthates.'' 3. Photosynthesis proceeds at a measurable rate even at the lowest CO{sub 2} pressures observed (0.03 mm Hg). There is no evidence for a ''threshold'' concentration of carbon dioxide for the reaction; at the lowest concentrations reached, respiration exactly equals assimilation, 4. The mean rate of respiratory CO{sub 2} evolution in strong light was found to be less than that in the dark. Internal re-photosynthesis of respiratory carbon may have been sufficient to account for this effect. 5. The assimilation of C{sup 14}O{sub 2} is about 17% slower than that of C{sup 12}O{sub 2}.

  10. BIOMASS AND MICROBIAL ACTIVITY UNDER DIFFERENT FOREST COVERS

    Directory of Open Access Journals (Sweden)

    Rafael Malfitano Braga

    2016-06-01

    Full Text Available This study evaluated the soil fertility, biomass and microbial activity of the soil under forest cover of Eucalyptus grandis, Eucalyptus pilularis, Eucalyptus cloeziana and Corymbia maculata; Pinus Caribbean var. hondurensis, 40 years old, and a fragment of Semideciduous Forest, located on the campus of the Federal University of Lavras. In soil samples collected in the 0-5 cm layer were determined fertility parameters, basal respiration and microbial biomass carbon. The results showed that for the species E. grandis and E. cloeziana the carbon of biomass microbial content was higher than for any other ecosystem evaluated, and equal to those observed under native forest. In contrast, the ground under Pinus had the lowest microbiological indexes. Under C. maculata and E. pilularis the contents were intermediate for this parameter. The basal respiration of all ecosystems was equal. The fertility level was very low in all types of evaluated vegetation.

  11. Experimental study on soil respiration of temperate grassland in China

    Institute of Scientific and Technical Information of China (English)

    WANG Gengchen; DU Rui; KONG Qinxin; L(U) Daren

    2004-01-01

    Experimental study on soil respiration of typical temperate grassland in Inner Mongolia was conducted in the period of 1998-2000. Closed chamber and GC/FID techniques were used for measurements of soil and plant respiration. Data analysis of three-year measurements show that temperate grassland soil respiration varied in the range of 390-866 gC/m2·a-1 and underwent evident seasonal and annual variations. On average, the soil respiration accounts for 70%-88% of the grassland total respiration. Results also show a stronger relation between the soil respiration and soil temperature in water abundant years. Increased rainfall in 1998 made soil respiration increased, while in the dry years, the relation between soil respiration and soil temperature weakened remarkably. Soit water content plays an important controlling role in soil respiration-temperature interrelation for semiarid grassland.

  12. Soil Respiration During a Soybean-Growing Season

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Soil respiration induced by soybean cultivation over its entire growing season and the factors influencing soil respiration were investigated to examine the seasonal pattern of soil respiration induced by soybean cultivation, explore soybean growth and photosynthesis on soil respiration, and determine the temperature dependence on soil respiration. Soil respiration in a pot experiment with and without soybean plants was sampled using the static chamber method and measured using gas chromatograph. Air temperature was a dominant factor controlling soil respiration rate in unplanted soil. Additionally,rhizosphere respiration comprised 62% to 98% of the soil respiration rate in the soybean-planted soil varying with the soybean growth stages. Harvesting aerial parts of soybean plant caused an immediate drop in the soil respiration rate at that stage. After harvesting the aerial parts of the soybean plant, a highly significant correlation between soil respiration rate and air temperature was found at the flowering stage (P < 0.01), the pod stage (P < 0.01), and the seed-filling stage(P < 0.05). Thus, rhizosphere respiration during the soybean-growing period not only made a great contribution to soil respiration, but also determined the seasonal variation pattern of the soil respiration rate.

  13. [Effects of nitrogen fertilization and straw amendment on soil microbial biomass and soil functions after heat stress].

    Science.gov (United States)

    Chen, Xiao-Yun; Chen, Shi; Liu, Man-Qiang; Jiao, Jia-Guo; Li, Hui-Xin; Hu, Feng

    2013-02-01

    A 60-day incubation experiment was conducted to study the effects of nitrogen fertilization (N), rice straw amendment (R), and their combination (RN) on the changes of soil microbial biomass and soil functions (basal respiration, substrate-induced respiration, and straw decomposition) after heat stress (40 degrees C for 18 h). Heat stress tended to promote the soil microbial biomass and soil functions, but the effects were weak and transient. Either with or without heating, treatment R and especially RN could greatly stimulate soil microbial biomass, basal respiration, substrate-induced respiration and straw decomposition, as compared to no straw amendment and with nitrogen fertilization alone, but the parameters in treatment N had less change, and even, presented a decreasing trend. It was suggested that straw amendment and its combination with nitrogen fertilization could improve soil functions in natural conditions or after environmental stress.

  14. Soil respiration responses to variation in temperature and moisture availability under woody plants and grasses

    Science.gov (United States)

    Pravalprukskul, P.; Pavao-Zuckerman, M.; Barron-Gafford, G. A.

    2011-12-01

    that autotrophic respiration drives soil respiration as soils develop. Over the course of soil evolution, changes in temperature sensitivity are expected as organic material and the microbial community develop. The continuation of this study over a nine-month period for a wider range of precipitation event sizes could provide important findings for soil respiration and climate change models.

  15. Soil respiration partition and its components in the total agro-ecosystem respiration

    Science.gov (United States)

    Delogu, Emilie; LeDantec, Valerie; Mordelet, Patrick; Buysse, Pauline; Aubinet, Marc; Pattey, Elizabeth; Mary, Bruno

    2013-04-01

    Close to 15% of the Earth's terrestrial surface is used for cropland. In the context of global warming, and acknowledged by the Kyoto Protocol, agricultural soils could be a significant sink for atmospheric CO2. Understanding the factors influencing carbon fluxes of agricultural soils is essential for implementing efficient mitigation practices. Most of the soil respiration modeling studies was carried out in forest ecosystems, but only a few was carried out in agricultural ecosystems. In the study, we evaluated simple formalisms to model soil respiration using wheat data from four contrasting geographical mi-latitude regions. Soil respiration were measured in three winter wheat fields at Lamasquère (43°49'N, 01°23'E, 2007) and Auradé (43°54'N, 01°10'E, 2008), South-West France and Lonzée (50°33'N, 4°44'E, 2007), Belgium, and in a spring wheat field at Ottawa (45°22'N, 75°43'W, 2007, 2011), Ontario, Canada. Manual closed chambers were used in the French sites. The Belgium and Canadian sites were equipped with automated closed chamber systems, which continuously collected 30-min soil respiration exchanges. All the sites were also equipped with eddy flux towers. When eddy flux data were collected over bare soil, the net ecosystem exchange (NEE) was equal to soil respiration exchange. These NEE data were used to validate the model. Different biotic and abiotic descriptors were used to model daily soil respiration and its heterotrophic and autotrophic components: soil temperature, soil relative humidity, Gross Primary Productivity (GPP), shoot biomass, crop height, with different formalisms. It was interesting to conclude that using biotic descriptors did not improve the performances of the model. In fact, a combination of abiotic descriptors (soil humidity and soil temperature) allowed significant model formalism to model soil respiration. The simple soil respiration model was used to calculate the heterotrophic and autotrophic source contributions to

  16. A New Approach to Predict Microbial Community Assembly and Function Using a Stochastic, Genome-Enabled Modeling Framework

    Science.gov (United States)

    King, E.; Brodie, E.; Anantharaman, K.; Karaoz, U.; Bouskill, N.; Banfield, J. F.; Steefel, C. I.; Molins, S.

    2016-12-01

    Characterizing and predicting the microbial and chemical compositions of subsurface aquatic systems necessitates an understanding of the metabolism and physiology of organisms that are often uncultured or studied under conditions not relevant for one's environment of interest. Cultivation-independent approaches are therefore important and have greatly enhanced our ability to characterize functional microbial diversity. The capability to reconstruct genomes representing thousands of populations from microbial communities using metagenomic techniques provides a foundation for development of predictive models for community structure and function. Here, we discuss a genome-informed stochastic trait-based model incorporated into a reactive transport framework to represent the activities of coupled guilds of hypothetical microorganisms. Metabolic pathways for each microbe within a functional guild are parameterized from metagenomic data with a unique combination of traits governing organism fitness under dynamic environmental conditions. We simulate the thermodynamics of coupled electron donor and acceptor reactions to predict the energy available for cellular maintenance, respiration, biomass development, and enzyme production. While `omics analyses can now characterize the metabolic potential of microbial communities, it is functionally redundant as well as computationally prohibitive to explicitly include the thousands of recovered organisms into biogeochemical models. However, one can derive potential metabolic pathways from genomes along with trait-linkages to build probability distributions of traits. These distributions are used to assemble groups of microbes that couple one or more of these pathways. From the initial ensemble of microbes, only a subset will persist based on the interaction of their physiological and metabolic traits with environmental conditions, competing organisms, etc. Here, we analyze the predicted niches of these hypothetical microbes and

  17. Management effects on European cropland respiration

    DEFF Research Database (Denmark)

    Eugster, W.; Moffat, A.; Ceschia, E.

    2010-01-01

    findings are based on all available CarboEurope IP eddy covariance flux measurements during a 4-year period (2004-2007). Detailed management information was available for 15 out of the 22 sites that contributed flux data, from which we compiled 30 types of management for European-scale comparison...... factors other than management alone are also important at a given site. Temperature is the climatic factor that showed best correlation with site-specific respiration fluxes. Therefore, the effect of temperature changes between the time periods before and after management were taken into account......Increases in respiration rates following management activities in croplands are considered a relevant anthropogenic source of CO2. In this paper, we quantify the impact of management events on cropland respiration fluxes of CO2 as they occur under current climate and management conditions. Our...

  18. Maintenance, endogeneous, respiration, lysis, decay and predation

    DEFF Research Database (Denmark)

    loosdrecht, Marc C. M. Van; Henze, Mogens

    1999-01-01

    In activated sludge processes an increased sludge age is associated with a decreased sludge production. This phenomenon is generally interpreted as a result of endogenous respiration processes. In the activated sludge models cell lysis (or decay) is incorporated. The lysis is modelled...... mechanism is microbiologically correct. The lysis/decay model mechanism is a strongly simplified representation of reality. This paper tries to review the processes grouped under endogenous respiration in activated sludge models. Mechanisms and processes such as maintenance, lysis, internal and external...... and maintenance processes. This conversion will in general be denoted as endogenous respiration. Based on the literature review the phenomena are discussed and organised, in order to create a working platform for discussing more detailed activated sludge models, one of which is being sketched. (C) 1999 IAWQ...

  19. Genotoxic activity and inhibition of soil respiration by ptaquiloside, a bracken fern carcinogen

    DEFF Research Database (Denmark)

    Schmidt, Bjørn; Rasmussen, L.H.; Svendsen, Gitte Winkel

    2005-01-01

    Ptaquiloside (PTA) is a natural toxin produced by bracken (Pteridium aquilinum [L.] Kuhn). Assessment of PTA toxicity is needed because PTA deposited from bracken to soil may leach to surface and groundwater. Inhibition of soil respiration and genotoxic activity of PTA was determined by a soil...... microbial carbon transformation test and an umu test, respectively. In the carbon transformation test, sandy loam soil was incubated at five different initial concentrations of PTA for a period of 28 d, after which glucose was added and respiration measured for 12 consecutive hours. The tests were performed...... at 20 degrees C and Soil moisture content of approximately 15%. For soil material sampled in the autumn, initial PTA concentrations ranging from 0.008 to 40.6 mu g PTA/g dry soil were tested. From fitting of data by a sigmoidal function, a 10% effect dose (ED10) was estimated to 13 jig PTA/g dry soil...

  20. Influence of low- and high-frequency electrical heating on biodegrading microorganisms in soil: soil respiration.

    Science.gov (United States)

    Roland, Ulf; Holzer, Frank; Kopinke, Frank-Dieter

    2013-01-01

    The influence of electrical heating on microbiological processes in soil has been studied to evaluate the potential for enhancing biodegradation of pollutants by controlling the temperature. A frequency of 50 Hz (power line frequency) was applied for resistive heating. Dielectric heating was realized using a frequency of 13.56 MHz (radio frequency). Both techniques were compared with conventional heating in a water bath. For experiments in laboratory and full scale, a model soil and a contaminated original soil were used. It was shown that under conditions capable for heating soil to 35 degrees C or even 60 degrees C, soil respiration as a measure for microbial activity was not hindered by electrical heating when temperature and moisture content were comparable with conventional heating. The variations of soil respiration were reversible upon temperature changes. Under certain conditions, periodical fluctuations of microbiological activity were observed. Several possible explanations including chronobiology are discussed without being able to provide an unambiguous interpretation for this effect.

  1. Organohalide Respiring Bacteria and Reductive Dehalogenases: Key Tools in Organohalide Bioremediation

    Directory of Open Access Journals (Sweden)

    Bat-Erdene eJugder

    2016-03-01

    Full Text Available Organohalides are recalcitrant pollutants that have been responsible for substantial contamination of soils and groundwater. Organohalide-respiring bacteria (ORB provide a potential solution to remediate contaminated sites, through their ability to use organohalides as terminal electron acceptors to yield energy for growth (i.e. organohalide respiration. Ideally, this process results in non- or lesser-halogenated compounds that are mostly less toxic to the environment or more easily degraded. At the heart of these processes are reductive dehalogenases (RDase, which are membrane bound enzymes coupled with other components that facilitate dehalogenation of organohalides to generate cellular energy. This review focuses RDases, concentrating on those which have been purified (partially or wholly and functionally characterized. Further, the paper reviews the major bacteria involved in organohalide breakdown and the evidence for microbial evolution of RDases. Finally, the capacity for using ORB in a bioremediation and bioaugmentation capacity are discussed.

  2. Soil microorganisms can overcome respiration inhibition by coupling intra- and extracellular metabolism: (13)C metabolic tracing reveals the mechanisms.

    Science.gov (United States)

    K Bore, Ezekiel; Apostel, Carolin; Halicki, Sara; Kuzyakov, Yakov; Dippold, Michaela A

    2017-06-01

    CO2 release from soil is commonly used to estimate toxicity of various substances on microorganisms. However, the mechanisms underlying persistent CO2 release from soil exposed to toxicants inhibiting microbial respiration, for example, sodium azide (NaN3) or heavy metals (Cd, Hg, Cu), remain unclear. To unravel these mechanisms, NaN3-amended soil was incubated with position-specifically (13)C-labeled glucose and (13)C was quantified in CO2, bulk soil, microbial biomass and phospholipid fatty acids (PLFAs). High (13)C recovery from C-1 in CO2 indicates that glucose was predominantly metabolized via the pentose phosphate pathway irrespective of inhibition. Although NaN3 prevented (13)C incorporation into PLFA and decreased total CO2 release, (13)C in CO2 increased by 12% compared with control soils due to an increased use of glucose for energy production. The allocation of glucose-derived carbon towards extracellular compounds, demonstrated by a fivefold higher (13)C recovery in bulk soil than in microbial biomass, suggests the synthesis of redox active substances for extracellular disposal of electrons to bypass inhibited electron transport chains within the cells. PLFA content doubled within 10 days of inhibition, demonstrating recovery of the microbial community. This growth was largely based on recycling of cost-intensive biomass compounds, for example, alkyl chains, from microbial necromass. The bypass of intracellular toxicity by extracellular electron transport permits the fast recovery of the microbial community. Such efficient strategies to overcome exposure to respiration-inhibiting toxicants may be exclusive to habitats containing redox-sensitive substances. Therefore, the toxic effects of respiration inhibitors on microorganisms are much less intensive in soils than in pure cultures.

  3. Computing partial-shift respirator use periods

    Energy Technology Data Exchange (ETDEWEB)

    Shotwell, H.P.; Caporossi, J.C.

    1983-02-01

    Airborne contaminant concentrations cannot always be reduced to desired levels even after the installation of feasible engineering controls. The industrial hygienist may have to recommend full-shift or partial-shift use of appropriate respirators to reduce exposures. The method described allows a recommendation to be made of the minimum period of time an exposed employee needs to use a repirator in order to reach the desired exposure level. The procedure is based on the calculation of time-weighted averages, using the upper confidence levels of air sampling data, and the respirator protection factors.

  4. BOREAS TE-2 Wood Respiration Data

    Science.gov (United States)

    Ryan, Michael G.; Lavigne, Michael; Hall, Forrest G. (Editor); Papagno, Andrea (Editor)

    2000-01-01

    The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set contains measurements of wood respiration conducted in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  5. BOREAS TE-2 Foliage Respiration Data

    Science.gov (United States)

    Ryan, Michael G.; Hall, Forrest G. (Editor); Lavigne, Michael; Papagno, Andrea (Editor)

    2000-01-01

    The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set contains measurements of foliar respiration conducted in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  6. BOREAS TE-2 Root Respiration Data

    Science.gov (United States)

    Ryan, Michael G.; Lavigne, Michael; Hall, Forrest G. (Editor); Papagno, Andrea (Editor)

    2000-01-01

    The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set includes means of tree root respiration measurements on roots having diameters ranging from 0 to 2 mm conducted in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  7. BOREAS TE-2 Continuous Wood Respiration Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Ryan, Michael G.; Lavigne, Michael

    2000-01-01

    The BOREAS TE-2 team collected several data sets in support of its efforts to characterize and interpret information on the respiration of the foliage, roots, and wood of boreal vegetation. This data set contains measurements of wood respiration measured continuously (about once per hour) in the NSA during the growing season of 1994. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  8. Photosynthesis, respiration, and carbon turnover in sinking marine snow from surface waters of Southern California Bight: implications for the carbon cycle in the ocean

    DEFF Research Database (Denmark)

    Ploug, H.; Grossart, HP; Azam, F.

    1999-01-01

    aggregate in darkness, which yielded a turnover time of 8 to 9 d for the total organic carbon in aggregates. Thus, marine snow is not only a vehicle for vertical flux of organic matter; the aggregates are also hotspots of microbial respiration which cause a fast and efficient respiratory turnover...... of particulate organic carbon in the sea....

  9. Contribution of Root Respiration to Total Soil Respiration in a Cotton Field of Northwest China

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhi-Min; ZHAO Cheng-Yi; Y.YILIHAMU; LI Ju-Yan; LI Jun

    2013-01-01

    To measure the contribution of root respiration (Rr) to total soil respiration (Rt) in arid cotton fields,eighteen plots,nine for girdling and nine control,were built in an arid cotton field in the Aksu National Experimental Station of Oasis Farmland Ecosystem,Xinjiang of China.Given the difference of soil respiration between girdled plots and non-girdled control plots,the components of soil respiration,root respiration (Rr) and respiration originating from decomposition (Rd) were divided.The temperature sensitivities of Rr and Rd were analyzed,respectively.The results showed that the average contribution of Rr to Rt in arid cotton field was about 32% during the study period.The temperature-response curve of Rr differed from that of Rd.The dynamic variation of Rd was more related to the change of soil temperature as compared to Rr.Rr and Rd had different responses to the variation of environment,and thus new models capable of differentiating between Rr and Rd are needed for evaluating the different factors controlling these two components of soil respiration in arid cotton field.

  10. Respiration the forgotten flux: new insights on ecosystem respiration and its global significance

    Science.gov (United States)

    Ballantyne, Ashley

    2017-04-01

    There is strong evidence that most of the variability in the global carbon cycle is due to processes occurring in the terrestrial biosphere; however, identifying these processes is extremely challenging. The two largest fluxes in the global carbon cycle are gross primary productivity and total respiration of the terrestrial biosphere. Considerable research has focused on factors controlling primary productivity, but total respiration has received much less attention. Here results are shared indicating that much of the previously identified variability in the global carbon cycle is due to the temperature sensitivity of respiration in the tropics. Furthermore, the recent acceleration in net terrestrial carbon uptake is due to diminished respiration during the recent warming hiatus. Lastly, total soil respiration at the global scale is sensitive to precipitation and soil moisture. I hypothesize that this reflects the sensitivity of autotrophic respiration to precipitation and the sensitivity of heterotrophic respiration to soil moisture. I am seeking creative ways in which to experimentally test this hypothesis through experimental manipulation or model simulation.

  11. Temperature response of soil respiration is dependent on concentration of readily decomposable C

    Directory of Open Access Journals (Sweden)

    A. A. Larionova

    2007-12-01

    Full Text Available Temperature acclimation of soil organic matter (SOM decomposition is one of the major uncertainties in predicting soil CO2 efflux associated with the increase in global mean temperature. A reasonable explanation for an apparent acclimation proposed by Davidson and colleagues (2006 based on Michaelis-Menten kinetics suggests that temperature sensitivity decreases when both maximal activity of respiratory enzymes (Vmax and half-saturation constant (Ks cancel each other upon temperature increase. We tested the hypothesis of the canceling effect by the mathematical simulation of data obtained in incubation experiments with forest and arable soils. Our data support the hypothesis and suggest that concentration of readily decomposable C substrate (as glucose equivalents and temperature dependent substrate release are the important factors controlling temperature sensitivity of soil respiration. The highest temperature sensitivity of soil respiration was observed when substrate release was temperature dependent and C substrate concentration was much lower than Ks. Increase of substrate content to the half-saturation constant by glucose addition resulted in temperature acclimation associated with the canceling effect. Addition of the substrate to the level providing respiration at a maximal rate Vmax leads to the acclimation of the whole microbial community as such. However, growing microbial biomass was more sensitive to the temperature alterations. This study improves our understanding of the instability of temperature sensitivity of soil respiration under field conditions, attributing this phenomenon to changes in concentration of readily decomposable C substrate.

  12. Microbial Transformation of Arsenic

    Science.gov (United States)

    Stolz, J. F.

    2004-12-01

    Whether the source is natural or anthropogenic, it has become evident that arsenic is readily transformed by a great diversity of microbial species and has a robust biogeochemical cycle. Arsenic cycling primarily involves the oxidation of As(III) and the reduction of As(V). Over thirty arsenite oxidizing prokaryotes have been reported and include alpha, beta, and gamma Proteobacteria , Deinocci and Crenarchaeota. At least twenty species of arsenate-respiring prokaryotes are now known and include Crenarchaeota, thermophilic bacteria, low and high G+C gram positive bacteria, and gamma, delta, and epsilon Proteobacteria. These organisms are metabolically diverse, and depending on the species, capable of using other terminal electron acceptors (e.g., nitrate, selenate, fumarate, sulfate). In addition to inorganic forms (e.g., sodium arsenate) organoarsenicals can be utilized as a substrate. The feed additive roxarsone (3-nitro-4-hydroxyphenyl arsonic acid) has been shown to readily degrade leading to the release of inorganic arsenic (e.g., As(V)). Degradation proceeds via the cleavage of the arsenate functional group or the reduction of the nitro functional group and deamination. The rapid degradation (within 3 days) of roxarsone by Clostridium sp. strain OhILAs appears to follow the latter pathway and may involve Stickland reactions. The activities of these organisms affect the speciation and mobilization of arsenic, ultimately impacting water quality.

  13. Mountain pine beetle disturbance effects on soil respiration and nutrient pools

    Science.gov (United States)

    Trahan, N. A.; Moore, D. J.; Brayden, B. H.; Dynes, E.; Monson, R. K.

    2011-12-01

    Over the past decade, the mountain pine beetle Dendroctonos ponderosae has infested more than 86 million hectares of high elevation forest in the Western U.S.A. While bark beetles are endemic to western forests and important agents of regeneration, the current mountain pine beetle outbreak is larger than any other on record and the resulting tree mortality has significant consequences for nutrient cycling and regional carbon exchange. We established decade-long parallel disturbance chronosequences in two lodgepole pine (Pinus contorta) forests in Colorado: one composed of mountain pine beetle killed lodgepole stands and one consisting of trees where beetle mortality was simulated by stem girdling. Over the 2010 and 2011 growing season we measured plot level soil respiration fluxes, as well as soil extractable dissolved organic carbon, nitrogen, microbial biomass carbon and nitrogen, and pools of ammonium, nitrate and inorganic phosphorus. We show that soil respiration sharply declines with gross primary productivity after tree mortality, but rebounds during the next 4 years, then declines again from 6-8 years post-disturbance. Soil extractable dissolved organic carbon, microbial biomass carbon, and inorganic phosphorous pools follow the pattern observed in soil respiration fluxes across disturbance age classes for both sites, while patterns in total dissolved nitrogen exhibit site specific variation. Levels of detectable soil nitrate were low and did not significantly change across the chronosequence, while soil ammonium increased in a similar pattern with soil moisture in disturbed plots. These patterns in soil respiration and nutrient pools reflect the loss of autotrophic respiration and rhizodeposition immediately after tree mortality, followed by a pulse in soil efflux linked to the decomposition of older, less labile carbon pools. This pulse is likely controlled by the fall rate of litter, coarse woody debris and the relative impact of post-disturbance water

  14. A meta-analysis of soil microbial biomass responses to forest disturbances

    Directory of Open Access Journals (Sweden)

    Sandra Robin Holden

    2013-06-01

    Full Text Available Climate warming is likely to increase the frequency and severity of forest disturbances, with uncertain consequences for soil microbial communities and their contribution to ecosystem C dynamics. To address this uncertainty, we conducted a meta-analysis of 139 published soil microbial responses to forest disturbances. These disturbances included abiotic (fire, harvesting, storm and biotic (insect, pathogen disturbances. We hypothesized that soil microbial biomass would decline following forest disturbances, but that abiotic disturbances would elicit greater reductions in microbial biomass than biotic disturbances. In support of this hypothesis, across all published studies, disturbances reduced soil microbial biomass by an average of 29.4%. However, microbial responses differed between abiotic and biotic disturbances. Microbial responses were significantly negative following fires, harvest, and storms (48.7%, 19.1%, and 41.7% reductions in microbial biomass, respectively. In contrast, changes in soil microbial biomass following insect infestation and pathogen-induced tree mortality were non-significant, although biotic disturbances were poorly represented in the literature. When measured separately, fungal and bacterial responses to disturbances mirrored the response of the microbial community as a whole. Changes in microbial abundance following disturbance were significantly positively correlated with changes in microbial respiration. We propose that the differential effect of abiotic and biotic disturbances on microbial biomass may be attributable to differences in soil disruption and organic C removal from forests among disturbance types. Altogether, these results suggest that abiotic forest disturbances may significantly decrease soil microbial abundance, with corresponding consequences for microbial respiration. Further studies are needed on the effect of biotic disturbances on forest soil microbial communities and soil C dynamics.

  15. Role of vermicompost chemical composition, microbial functional diversity, and fungal community structure in their microbial respiratory response to three pesticides.

    Science.gov (United States)

    Fernández-Gómez, Manuel J; Nogales, Rogelio; Insam, Heribert; Romero, Esperanza; Goberna, Marta

    2011-10-01

    The relationships between vermicompost chemical features, enzyme activities, community-level physiological profiles (CLPPs), fungal community structures, and its microbial respiratory response to pesticides were investigated. Fungal community structure of vermicomposts produced from damaged tomato fruits (DT), winery wastes (WW), olive-mill waste and biosolids (OB), and cattle manure (CM) were determined by denaturing gradient gel electrophoresis of 18S rDNA. MicroResp™ was used for assessing vermicompost CLPPs and testing the microbial response to metalaxyl, imidacloprid, and diuron. Vermicompost enzyme activities and CLPPs indicated that WW, OB, and DT had higher microbial functional diversity than CM. The microbiota of the former tolerated all three pesticides whereas microbial respiration in CM was negatively affected by metalaxyl and imidacloprid. The response of vermicompost microbiota to the fungicide metalaxyl was correlated to its fungal community structure. The results suggest that vermicomposts with higher microbial functional diversity can be useful for the management of pesticide pollution in agriculture.

  16. δ 13C of ecosystem-respired CO2 along a gradient of C3 woody-plant encroachment into C4 grassland

    Science.gov (United States)

    Sun, W.; Scott, R. L.; Resco, V.; Cable, J. M.; Huxman, T. E.; Williams, D. G.

    2006-12-01

    Woody plant encroachment into grassland has the potential to affect net primary production, in part by changing the sensitivities of photosynthesis and respiration to precipitation. Encroachment of mesquite (Prosopis) into floodplain sacaton (Sporobolus) grassland along the San Pedro River in southeastern Arizona has altered the magnitude and seasonal pattern of net ecosystem carbon exchange and ecosystem respiration. We hypothesized that because mesquite accesses ground water in these floodplain environments, its advancement and dominance in former grassland reduces the sensitivities of photosynthesis and autotrophic respiration to inputs of growing season precipitation. The observed elevated rates of ecosystem respiration following rainfall inputs are likely to result from microbial decomposition of labile organic matter derived from the highly productive mesquite trees. We used the Keeling plot method to monitor carbon-13 composition of nocturnal ecosystem-respired CO2 (δ 13CR) during the growing seasons of 2005 and 2006 at three sites spanning a gradient of mesquite invasion: C4 sacaton grassland, mixed mesquite/grass shrubland and C3 mesquite woodland. δ 13CR in the C4 grassland increased from -18.8‰ during the dry premonsoon period to -16.7‰ after the onset of summer rains, whereas δ 13CR in the mixed shrub/grass and woodland ecosystems declined from -20.9‰ to - 24‰ and from -20.8‰ to -24.7‰, respectively, following the onset of summer rains. The δ 13CR of respired CO2 was collected separately from soil, roots, leaves and surface litter to evaluate the contribution of each of these components to ecosystem respiration. Partitioning of ecosystem respiration using these isotope end-members and responses to short-term (days) changes in shallow (0-5cm) soil moisture content suggest that in former grassland now occupied by mesquite woodland, rainfall inputs primarily stimulate microbial decomposition and have little effect on autotrophic respiration

  17. Respiration in Heterotrophic Unicellular Eukaryotic Organisms

    DEFF Research Database (Denmark)

    Fenchel, Tom

    2014-01-01

    about 10% and mitochondria are predominantly found close to the outer membrane. The results predict that for small and medium sized protozoa maximum respiration rates should be proportional to cell volume (scaling exponent ≈1) and access to intracellular O2 is not limiting except at very low ambient O2...

  18. Estimating Canopy Dark Respiration for Crop Models

    Science.gov (United States)

    Monje Mejia, Oscar Alberto

    2014-01-01

    Crop production is obtained from accurate estimates of daily carbon gain.Canopy gross photosynthesis (Pgross) can be estimated from biochemical models of photosynthesis using sun and shaded leaf portions and the amount of intercepted photosyntheticallyactive radiation (PAR).In turn, canopy daily net carbon gain can be estimated from canopy daily gross photosynthesis when canopy dark respiration (Rd) is known.

  19. Respiration patterns of resting wasps (Vespula sp.).

    Science.gov (United States)

    Käfer, Helmut; Kovac, Helmut; Stabentheiner, Anton

    2013-04-01

    We investigated the respiration patterns of wasps (Vespula sp.) in their viable temperature range (2.9-42.4°C) by measuring CO2 production and locomotor and endothermic activity. Wasps showed cycles of an interburst-burst type at low ambient temperatures (Ta31°C, CO2 emission became cyclic. With rising Ta they enhanced CO2-emission primarily by an exponential increase in respiration frequency, from 2.6 mHz at 4.7°C to 74 mHz at 39.7°C. In the same range of Ta CO2 release per cycle decreased from 38.9 to 26.4 μl g(-1)cycle(-1). A comparison of wasps with other insects showed that they are among the insects with a low respiratory frequency at a given resting metabolic rate (RMR), and a relatively flat increase of respiratory frequency with RMR. CO2 emission was always accompanied by abdominal respiration movements in all open phases and in 71.4% of the flutter phases, often accompanied by body movements. Results suggest that resting wasps gain their highly efficient gas exchange to a considerable extent via the length and type of respiration movements.

  20. Do Tree Stems Recapture Respired CO2?

    Science.gov (United States)

    Hilman, B.; Angert, A.

    2016-12-01

    Tree stem respiration is an important, yet not well understood, component of the terrestrial carbon cycle. Predicting how trees as whole organisms respond to changes in climate and atmospheric CO2 requires understanding of the variability in the fraction of assimilated carbon allocated to respiration, versus the allocation to growth, damage repair, and to rhizosphere symbionts. Here we used the ratio of CO2 efflux/O2 influx (Apparent Respiratory Quotient, ARQ) to study stem respiration. The ARQ in trees stems is predicted to be 1.0, as a result of carbohydrates metabolism. Lower than 1.0 ARQ values may indicate a local assimilation of respired CO2, or dissolution and transport of CO2 in the xylem stream. We measured stems ARQ in 16 tree species at tropical, Mediterranean and temperate ecosystems using stem chambers and in-vitro incubations. The CO2 and O2 were measured by a system we developed, which is based on an IRGA and a Fuel-cell O2 analyzer (Hilman and Angert 2016). We found typical values of ARQ in the range of 0.4-0.8. Since incubations of detach stem tissues yielded similar ARQ values, and since the influence of natural variations in the transpiration stream on ARQ was found to be small, we conclude that the removal of the respired CO2 is not via dissolution in the xylem stream. Using 13C labeling, dark fixation of stem tissues was detected, which is most probably phosphoenolpyruvate carboxylase (PEPC) mediated. Hence, we suggest that in-stem dark fixation of respired CO2 to organic acids (e.g. malate) affects the outgoing efflux. Further research should determine if these organic acids are transported to the canopy, stored in the stem, or transported to the roots to serve as exudates. Hilman B, Angert A (2016) Measuring the ratio of CO2 efflux to O2 influx in tree stem respiration. Tree Physiol 2016, doi: 10.1093/treephys/tpw057

  1. Toward a general evaluation model for soil respiration (GEMSR)

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Soil respiration is an important component of terrestrial carbon budget. Its accurate evaluation is es- sential to the study of terrestrial carbon source/sink. Studies on soil respiration at present mostly focus on the temporal variations and the controlling factors of soil respiration, but its spatial variations and controlling factors draw less attention. Moreover, the evaluation models for soil respiration at present include only the effects of water and heat factors, while the biological and soil factors controlling soil respiration and their interactions with water and heat factors have not been considered yet. These models are not able to accurately evaluate soil respiration in different vegetation/terrestrial ecosystems at different temporal and spatial scales. Thus, a general evaluation model for soil respiration (GEMSR) including the interacting meteorological (water and heat factors), soil nutrient and biological factors is suggested in this paper, and the basic procedure developing GEMSR and the research tasks of soil respiration in the future are also discussed.

  2. Toward a general evaluation model for soil respiration (GEMSR)

    Institute of Scientific and Technical Information of China (English)

    ZHOU GuangSheng; JIA BingRui; HAN GuangXuan; ZHOU Li

    2008-01-01

    Soil respiration is an important component of terrestrial carbon budget. Its accurate evaluation is essential to the study of terrestrial carbon source/sink. Studies on soil respiration at present mostly focus on the temporal variations and the controlling factors of soil respiration, but its spatial variations and controlling factors draw less attention. Moreover, the evaluation models for soil respiration at present include only the effects of water and heat factors, while the biological and soil factors controlling soil respiration and their interactions with water and heat factors have not been considered yet. These models are not able to accurately evaluate soil respiration in different vegetation/terrestrial ecosystems at different temporal and spatial scales. Thus, a general evaluation model for soil respiration (GEMSR)including the interacting meteorological (water and heat factors), soil nutrient and biological factors is suggested in this paper, and the basic procedure developing GEMSR and the research tasks of soil respiration in the future are also discussed.

  3. Metabolic interactions between methanogenic consortia and anaerobic respiring bacteria

    DEFF Research Database (Denmark)

    Stams, A.J.; Oude Elferink, S.J.; Westermann, Peter

    2003-01-01

    Most types of anaerobic respiration are able to outcompete methanogenic consortia for common substrates if the respective electron acceptors are present in sufficient amounts. Furthermore, several products or intermediate compounds formed by anaerobic respiring bacteria are toxic to methanogenic...

  4. [Endogenous respiration process analysis of heterotrophic biomass and autotrophic biomass based on respiration map ].

    Science.gov (United States)

    Li, Zhi-hua; Bai, Xu-li; Zhang, Qin; Liu, Yi; He, Chun-bo

    2014-09-01

    The endogenous process is an important metabolic part of the activated sludge, and the understanding of this process is still unclear. Characteristics of endogenous respiration for heterotrophic bacteria and autotrophic nitrifiers were analyzed using respirogram. Results showed that both heterotrophic and autotrophic bacteria entered the stage of endogenous respiration at almost the same time, but heterotrophic bacteria first entered the stage of dormancy i. e. , they were easier to recover a higher proportion of biomass during the dormancy stage, indicating that heterotrophic bacteria exhibited strong environmental adaptability. Autotrophic bacteria were, however, quite different. This finding confirmed that autotrophic bacteria were more vulnerable from the viewpoint of endogenous respiration. In addition, the study also found that the increase of endogenous respiration rate ratio reflected the decreased sludge activity. And the proportion of endogenous respiration was an important parameter to characterize the activity of activated sludge, which can be used as a quantitative index for the health status of activated sludge. The findings further deepened the understanding of endogenous respiration process and provided a theoretical basis for the operation and management of wastewater treatment plants.

  5. 42 CFR 84.1134 - Respirator containers; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Respirator containers; minimum requirements. 84..., Fume, and Mist; Pesticide; Paint Spray; Powered Air-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1134 Respirator containers; minimum requirements. (a) Except as provided...

  6. 75 FR 20546 - Total Inward Leakage Requirements for Respirators

    Science.gov (United States)

    2010-04-20

    ... HUMAN SERVICES 42 CFR Part 84 RIN 0920-AA33 Total Inward Leakage Requirements for Respirators AGENCY... Respirators,'' published in the Federal Register on October 30, 2009 (74 FR 56141). The comment period on this... total inward leakage (TIL) requirements for half-mask air-purifying particulate respirators approved...

  7. 42 CFR 84.1156 - Pesticide respirators; performance requirements; general.

    Science.gov (United States)

    2010-10-01

    ... resistance will be measured in the facepiece, mouthpiece, hood, or helmet of a pesticide respirator mounted... allowable resistance requirements for pesticide respirators are as follows: Maximum Resistance Type of... 42 Public Health 1 2010-10-01 2010-10-01 false Pesticide respirators; performance...

  8. Quantifying soil respiration at landscape scales. Chapter 11

    Science.gov (United States)

    John B. Bradford; Michael G. Ryan

    2008-01-01

    Soil CO2, efflux, or soil respiration, represents a substantial component of carbon cycling in terrestrial ecosystems. Consequently, quantifying soil respiration over large areas and long time periods is an increasingly important goal. However, soil respiration rates vary dramatically in space and time in response to both environmental conditions...

  9. 21 CFR 892.1970 - Radiographic ECG/respirator synchronizer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic ECG/respirator synchronizer. 892.1970... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1970 Radiographic ECG/respirator synchronizer. (a) Identification. A radiographic ECG/respirator synchronizer is a device intended to be used...

  10. Microbial xanthophylls.

    Science.gov (United States)

    Bhosale, Prakash; Bernstein, Paul S

    2005-09-01

    Xanthophylls are oxygenated carotenoids abundant in the human food supply. Lutein, zeaxanthin, and cryptoxanthin are major xanthophyll carotenoids in human plasma. The consumption of these xanthophylls is directly associated with reduction in the risk of cancers, cardiovascular disease, age-related macular degeneration, and cataract formation. Canthaxanthin and astaxanthin also have considerable importance in aquaculture for salmonid and crustacean pigmentation, and are of commercial interest for the pharmaceutical and food industries. Chemical synthesis is a major source for the heavy demand of xanthophylls in the consumer market; however, microbial producers also have potential as commercial sources. In this review, we discuss the biosynthesis, commercial utility, and major microbial sources of xanthophylls. We also present a critical review of current research and technologies involved in promoting microbes as potential commercial sources for mass production.

  11. Microbially Mediated Immobilization of Contaminants Through In Situ Biostimulation

    Energy Technology Data Exchange (ETDEWEB)

    Scott Fendorf

    2003-07-31

    In most natural environments, a multitude of metabolic substrates are resent simultaneously. Organisms that can utilize uranium as a metabolic substrate for respiration also may have the ability to use a variety of other oxidized substrates as electron acceptors. Thus, these substrates are, in effect, competing for electrons that are being passed through the electron transport chain during respiration. To assess the feasibility of in situ immobilization of uranium in subsurface environments and to understand the cycling of uranium, it is necessary to discern the chemical and/or biological conditions dictating which terminal electron acceptor(s) will be utilized.

  12. Factors for Microbial Carbon Sources in Organic and Mineral Soils from Eastern United States Deciduous Forests

    Energy Technology Data Exchange (ETDEWEB)

    Stitt, Caroline R. [Mills College, Oakland, CA (United States)

    2013-09-16

    Forest soils represent a large portion of global terrestrial carbon; however, which soil carbon sources are used by soil microbes and respired as carbon dioxide (CO2) is not well known. This study will focus on characterizing microbial carbon sources from organic and mineral soils from four eastern United States deciduous forests using a unique radiocarbon (14C) tracer. Results from the dark incubation of organic and mineral soils are heavily influenced by site characteristics when incubated at optimal microbial activity temperature. Sites with considerable differences in temperature, texture, and location differ in carbon source attribution, indicating that site characteristics play a role in soil respiration.

  13. Effects of different vegetation restoration models on soil microbial biomass in eroded hilly Loess Plateau, China

    Institute of Scientific and Technical Information of China (English)

    XUE Sha; LIU Guobin; DAI Quanhou; LAN Xue; YU Na

    2007-01-01

    Vegetation restoration is a key measure to improve the eco-environment in Loess Plateau,China.In order to find the effect of soil microbial biomass under different vegetation restoration models in this region,six trial sites located in Zhifanggou watershed were selected in this study.Results showed that soil microbial biomass,microbial respiration and physical and chemical properties increased apparently.After 30 years of vegetation restoration,soil microbial biomass C,N,P(SMBC,SMBN,SMBP)and microbial respiration,increased by 109.01%-144.22%,34.17%-117.09%,31.79%-79.94% and 26.78%-87.59% respectively,as compared with the farmland.However,metabolic quotient declined dramatically by 57.45%-77.49%.Effects of different models of vegetation restoration are different on improving the properties of soil.In general,mixed stands of Pinus tabulaeformisAmorpha fruticosa and Robinia pseudoacacia-A,fruticosa had the most remarkable effect,followed by R.pseudoacacia and Caragana korshinkii,fallow land and P.tabulaeformis was the lowest.Restoration of mixed forest had greater effective than pure forest in eroded Hilly Loess Plateau.The significant relationships were observed among SMBC,SMBP,microbial respiration,and physical and chemical properties of soil.It was concluded that microbial biomass can be used as indicators of soil quality.

  14. Influencing factors and partitioning of respiration in a Leymus chinensis steppe in Xilin River Basin, Inner Mongolia, China%内蒙古锡林河流域羊草草原植物生长旺季呼吸的影响因素分析和区分

    Institute of Scientific and Technical Information of China (English)

    耿元波; 罗光强

    2011-01-01

    Based on the static opaque chamber method, the respiration rates of soil microbial respiration, soil respiration, and ecosystem respiration were measured through continuous in-situ experiments during rapid growth season in semiarid Leymus chinensis steppe in the Xilin River Basin of Inner Mongolia, China. Soil temperature and moisture were the main factor affecting respiration rates. Soil temperature can explain most CO2 efflux variations (R2=0.376-0.655) excluding data of low soil water conditions. Soil moisture can also effectively explain most of the variations of soil and ecosystem respiration (R2=0.314-0.583), but it can not explain much of the variation of microbial respiration (R2=0.063). Low soil water content (≤5%) inhibited CO2 efflux though the soil temperature was high. Rewetting the soil after a long drought resulted in substantial increases in CO2 flux at high temperature. Bivariable models based on soil temperature at 5 cm depth and soil moisture at 0-10 cm depth can explain about 70% of the variations of CO2 effluxes. The contribution of soil respiration to ecosystem respiration averaged 59.4%, ranging from 47.3% to 72.4%; the contribution of root respiration to soil respiration averaged 20.5%, ranging from 11.7% to 51.7%. The contribution of soil to ecosystem respiration was a little overestimated and root to soil respiration little underestimated because of the increased soil water content that occurred as a result of plant removal.

  15. Soil resource availability impacts microbial response to organic carbon and inorganic nitrogen inputs

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-jian; W.ZHU; S.HU

    2005-01-01

    Impacts of newly added organic carbon (C) and inorganic nitrogen (N) on the microbial utilization of soil organic matter are important in determining the future C balance of terrestrial ecosystems. We examined microbial responses to cellulose and ammonium nitrate additions in three soils with very different C and N availability. These soils included an organic soil( 14.2% total organic C, with extremely high extractable N and low labile C), a forest soi1(4.7% total organic C, with high labile C and extremely low extractable N),and a grassland soil (1.6% total organic C, with low extractable N and labile C). While cellulose addition alone significantly enhanced microbial respiration and biomass C and N in the organic and grassland soils, it accelerated only the microbial respiration in the highly-N limited forest soil. These results indicated that when N was not limited, C addition enhanced soil respiration by stimulating both microbial growth and their metabolic activity. New C inputs lead to elevated C release in all three soils, and the magnitude of the enhancement was higher in the organic and grassland soils than the forest soil. The addition of cellulose plus N to the forest and grassland soils initially increased the microbial biomass and respiration rates, but decreased the rates as time progressed. Compared to cellulose addition alone,cellulose plus N additions increased the total C-released in the grassland soil, but not in the forest soil. The enhancement of total Creleased induced by C and N addition was less than 50% of the added-C in the forest soil after 96 d of incubation, in contrast to 87.5%and 89.0% in the organic and grassland soils. These results indicate that indigenous soil C and N availability substantially impacts the allocation of organic C for microbial biomass growth and/or respiration, potentially regulating the turnover rates of the new organic C inputs.

  16. Unraveling the mechanisms underlying pulse dynamics of soil respiration in tropical dry forests

    Science.gov (United States)

    Waring, Bonnie G.; Powers, Jennifer S.

    2016-10-01

    Tropical dry forests are already undergoing changes in the quantity and timing of rainfall, but there is great uncertainty over how these shifts will affect belowground carbon (C) cycling. While it has long been known that dry soils quickly release carbon dioxide (CO2) upon rewetting, the mechanisms underlying the so-called ‘Birch effect’ are still debated. Here, we quantified soil respiration pulses and their biotic predictors in response to simulated precipitation events in a regenerating tropical dry forest in Costa Rica. We also simulated the observed rewetting CO2 pulses with two soil carbon models: a conventional model assuming first-order decay rates of soil organic matter, and an enzyme-catalyzed model with Michaelis-Menten kinetics. We found that rewetting of dry soils produced an immediate and dramatic pulse of CO2, accompanied by rapid immobilization of nitrogen into the microbial biomass. However, the magnitude of the rewetting CO2 pulse was highly variable at fine spatial scales, and was well correlated with the size of the dissolved organic C pool prior to rewetting. Both the enzyme-catalyzed and conventional models were able to reproduce the Birch effect when respiration was coupled directly to microbial C uptake, although models differed in their ability to yield realistic estimates of SOC and microbial biomass pool sizes and dynamics. Our results suggest that changes in the timing and intensity of rainfall events in tropical dry forests will exert strong influence on ecosystem C balance by affecting the dynamics of microbial biomass growth.

  17. Insights on nitrate respiration by Shewanella

    Directory of Open Access Journals (Sweden)

    Fengping eWang

    2015-01-01

    Full Text Available Shewanellae are well known for their ability to utilize a number of electron acceptors and are therefore considered to have important roles in element cycling in the environment, such as nitrogen cycling through dissimilatory nitrate reduction to ammonia (DNRA and denitrification. Possessing two periplasmic nitrate reductase systems (NAP-α and NAP-β is a special trait of the Shewanella genus, and both enzymes are likely to provide selective advantage to the host. This review relates the current knowledge and aspects of the nitrate respiration system of Shewanella. Specifically, the potential physiological functions and regulation mechanisms of the duo-NAP system are discussed in addition to the evolution of anaerobic respiration systems of Shewanella.

  18. A MEMS turbine prototype for respiration harvesting

    Science.gov (United States)

    Goreke, U.; Habibiabad, S.; Azgin, K.; Beyaz, M. I.

    2015-12-01

    The design, manufacturing, and performance characterization of a MEMS-scale turbine prototype is reported. The turbine is designed for integration into a respiration harvester that can convert normal human breathing into electrical power through electromagnetic induction. The device measures 10 mm in radius, and employs 12 blades located around the turbine periphery along with ball bearings around the center. Finite element simulations showed that an average torque of 3.07 μNm is induced at 12 lpm airflow rate, which lies in normal breathing levels. The turbine and a test package were manufactured using CNC milling on PMMA. Tests were performed at respiration flow rates between 5-25 lpm. The highest rotational speed was measured to be 9.84 krpm at 25 lpm, resulting in 8.96 mbar pressure drop across the device and 370 mW actuation power.

  19. Cardiac, Skeletal, and smooth muscle mitochondrial respiration

    DEFF Research Database (Denmark)

    Park, Song-Young; Gifford, Jayson R; Andtbacka, Robert H I

    2014-01-01

    Unlike cardiac and skeletal muscle, little is known about vascular smooth muscle mitochondrial function. Therefore, this study examined mitochondrial respiratory rates in the smooth muscle of healthy human feed arteries and compared with that of healthy cardiac and skeletal muscle. Cardiac......, skeletal, and smooth muscle was harvested from a total of 22 subjects (53±6 yrs) and mitochondrial respiration assessed in permeabilized fibers. Complex I+II, state 3 respiration, an index of oxidative phosphorylation capacity, fell progressively from cardiac, skeletal, to smooth muscle (54±1; 39±4; 15......±1 pmol•s(-1)•mg (-1), psmooth muscle (222±13; 115±2; 48±2 umol•g(-1)•min(-1), p

  20. Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

    Directory of Open Access Journals (Sweden)

    Or Sperling

    Full Text Available Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq. cm(-3 yr(-1 on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics.

  1. Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

    Science.gov (United States)

    Sperling, Or; Earles, J Mason; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A

    2015-01-01

    Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC) availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq.) cm(-3) yr(-1) on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics.

  2. Exoelectrogenic bacteria that power microbial fuel cells

    KAUST Repository

    Logan, Bruce E.

    2009-03-30

    There has been an increase in recent years in the number of reports of microorganisms that can generate electrical current in microbial fuel cells. Although many new strains have been identified, few strains individually produce power densities as high as strains from mixed communities. Enriched anodic biofilms have generated power densities as high as 6.9 W per m2 (projected anode area), and therefore are approaching theoretical limits. To understand bacterial versatility in mechanisms used for current generation, this Progress article explores the underlying reasons for exocellular electron transfer, including cellular respiration and possible cell-cell communication.

  3. Geochemical Investigations of Respirable Particulate Matter

    OpenAIRE

    Jurinski, Joseph Bernard Jr.

    1998-01-01

    GEOCHEMICAL INVESTIGATIONS OF RESPIRABLE PARTICULATE MATTER Joseph Bernard Jurinski (Abstract) Over the course of our lives we are exposed to airborne particulate matter in the workplace, home, and environment that results in the deposition of millions of particles in the lung. These exposures may result in disease if they are significant enough. The potential for harmful exposure depends in part on the dust's biodurability and the bioavailability of harmful constituents d...

  4. The Role of Soil Organic Matter, Nutrients, and Microbial Community Structure on the Performance of Microbial Fuel Cells

    Science.gov (United States)

    Rooney-Varga, J. N.; Dunaj, S. J.; Vallino, J. J.; Hines, M. E.; Gay, M.; Kobyljanec, C.

    2011-12-01

    Microbial fuel cells (MFCs) offer the potential for generating electricity, mitigating greenhouse gas emissions, and bioremediating pollutants through utilization of a plentiful, natural, and renewable resource: soil organic carbon. In the current study, we analyzed microbial community structure, MFC performance, and soil characteristics in different microhabitats (bulk soil, anode, and cathode) within MFCs constructed from agricultural or forest soils in order to determine how soil type and microbial dynamics influence MFC performance. MFCs were constructed with soils from agricultural and hardwood forest sites at Harvard Forest (Petersham, MA). The bulk soil characteristics were analyzed, including polyphenols, short chain fatty acids, total organic C and N, abiotic macronutrients, N and P mineralization rates, CO2 respiration rates, and MFC power output. Microbial community structure of the anodes, cathodes, and bulk soils was determined with molecular fingerprinting methods, which included terminal restriction length polymorphism (T-RFLP) analysis and 16S rRNA gene sequencing analysis. Our results indicated that MFCs constructed from agricultural soil had power output about 17 times that of forest soil-based MFCs and respiration rates about 10 times higher than forest soil MFCs. Agricultural soil MFCs had lower C:N ratios, polyphenol content, and acetate concentrations than forest soil MFCs, suggesting that active agricultural MFC microbial communities were supported by higher quality organic carbon. Microbial community profile data indicate that the microbial communities at the anode of the high power MFCs were less diverse than in low power MFCs and were dominated by Deltaproteobacteria, Geobacter, and, to a lesser extent, Clostridia, while low-power MFC anode communities were dominated by Clostridia. These data suggest that the presence of organic carbon substrate (acetate) was not the major limiting factor in selecting for highly electrogenic microbial

  5. Key respiratory genes elucidate bacterial community respiration in a seasonally anoxic estuary.

    Science.gov (United States)

    Eggleston, Erin M; Lee, Dong Y; Owens, Michael S; Cornwell, Jeffrey C; Crump, Byron C; Hewson, Ian

    2015-07-01

    Intense annual spring phytoplankton blooms and thermohaline stratification lead to anoxia in Chesapeake Bay bottom waters. Once oxygen becomes depleted in the system, microbial communities use energetically favourable alternative electron acceptors for respiration. The extent to which changes in respiration are reflected in community gene expression have only recently been investigated. Metatranscriptomes prepared from near-bottom water plankton over a 4-month time series in central Chesapeake Bay demonstrated changes consistent with terminal electron acceptor availability. The frequency of respiration-related genes in metatranscriptomes was examined by BLASTx against curated databases of genes intimately and exclusively involved in specific electron acceptor utilization pathways. The relative expression of genes involved in denitrification and dissimilatory nitrate reduction to ammonium were coincident with changes in nitrate, nitrite and ammonium concentrations. Dissimilatory iron and manganese reduction transcript ratios increase during anoxic conditions and corresponded with the highest soluble reactive phosphate and manganese concentrations. The sulfide concentration peaked in late July and early August and also matched dissimilatory sulfate reduction transcript ratios. We show that rather than abrupt transitions between terminal electron acceptors, there is substantial overlap in time and space of these various anaerobic respiratory processes in Chesapeake Bay.

  6. Assessment of Innovation Competency

    DEFF Research Database (Denmark)

    Nielsen, Jan Alexis

    2015-01-01

    of the recorded talk in interaction that occurred in teacher group discussion sessions at 5 upper secondary schools. Based on the analysis, it was possible to extrapolate assessment criteria for 5 subcompetencies relevant to innovation (creative competency, collaboration competency, navigation competency, action...... competency, and communication competency) as well as assessment criteria for a number of skills relevant to these subcompetencies. These assessment criteria, it is argued, largely resonate with existing literature and they provide a detailed glimpse into how assessment of innovation competency could...

  7. Continuous respirable mine dust monitor development

    Energy Technology Data Exchange (ETDEWEB)

    Cantrell, B.K.; Williams, K.L.; Stein, S.W. [and others

    1996-12-31

    In June 1992, the Mine Safety and Health Administration (MSHA) published the Report of the Coal Mine Respirable Dust Task Group, Review of the Program to Control Respirable Coal Mine Dust in the United States. As one of its recommendations, the report called for the accelerated development of two mine dust monitors: (1) a fixed-site monitor capable of providing continuous information on dust levels to the miner, mine operator, and to MSHA, if necessary, and (2) a personal sampling device capable of providing both a short-term personal exposure measurement as well as a full-shift measurement. In response to this recommendation, the U.S. Bureau of Mines initiated the development of a fixed-site machine-mounted continuous respirable dust monitor. The technology chosen for monitor development is the Rupprecht and Patashnick Co., Inc. tapered element oscillating microbalance. Laboratory and in-mine tests have indicated that, with modification, this sensor can meet the humidity and vibration requirements for underground coal mine use. The U.S. Department of Energy Pittsburgh Research Center (DOE-PRC) is continuing that effort by developing prototypes of a continuous dust monitor based on this technology. These prototypes are being evaluated in underground coal mines as they become available. This effort, conducted as a joint venture with MSHA, is nearing completion with every promise of success.

  8. Microbial Metalloproteomics

    Directory of Open Access Journals (Sweden)

    Peter-Leon Hagedoorn

    2015-12-01

    Full Text Available Metalloproteomics is a rapidly developing field of science that involves the comprehensive analysis of all metal-containing or metal-binding proteins in a biological sample. The purpose of this review is to offer a comprehensive overview of the research involving approaches that can be categorized as inductively coupled plasma (ICP-MS based methods, X-ray absorption/fluorescence, radionuclide based methods and bioinformatics. Important discoveries in microbial proteomics will be reviewed, as well as the outlook to new emerging approaches and research areas.

  9. Bacterial Diversity, Sediment Age and Organic Respiration in the Marine Sedimentary Environment

    Science.gov (United States)

    Walsh, E. A.; Kirkpatrick, J. B.; Pockalny, R. A.; Sauvage, J.; Sogin, M. L.; D'Hondt, S.

    2014-12-01

    Subseafloor sediment hosts to a large1, taxonomically rich2 and metabolically diverse3 microbial ecosystem. However, the factors that control microbial diversity in subseafloor sediment have rarely been explored. Here we show that subseafloor bacterial richness varies directly with sediment age and net rate of organic-fueled respiration. We examined three open-ocean sites (in the Bering Sea and equatorial Pacific) and one continental margin site (Indian Ocean), with sediment depths to 404 meters below seafloor. At all locations, taxonomic richness decreases exponentially with increasing sediment age. Richness declines most rapidly for a few hundred thousand years after sediment deposition. This profile generally matches the canonical relationship between rates of organic oxidation and sediment age 4. To examine the potential link between organic oxidation and taxonomic richness we used pore-water chemical profiles to quantify net rates of organic respiration at the three open-ocean sites (the chemical profiles of the ocean-margin site are not in diffusive steady state). Taxonomic richness and total rate of organic-fueled respiration are highest at the high productivity Bering Sea site and lower at the moderate productivity equatorial Pacific sites. At each of these sites, organic-fueled respiration rate and taxonomic richness are highest at the surface and decline together as sediment depth and age increase. To our knowledge, this is the first evidence that taxonomic richness is closely linked to organic-fueled respiration rate and sediment age in subseafloor sediment. References1. Kallmeyer, J., Pockalny, R., Adhikari, R. R., Smith, D. C. & D'Hondt, S. Proceedings of the National Academy of Sciences, doi:10.1073/pnas.1203849109 (2012). 2. Inagaki, F. et al. Proceedings of the National Academy of Sciences 103, 2815-2820 (2006). 3. D'Hondt, S. et al. Science 306, 2216-2221, doi:10.1126/science.1101155 (2004). 4. Middelburg, J. J. Geochimica et Cosmochimica Acta 53

  10. Microbial Ecosystems, Protection of

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Nelson, K.E.

    2014-01-01

    Synonyms Conservation of microbial diversity and ecosystem functions provided by microbes; Preservation of microbial diversity and ecosystem functions provided by microbes Definition The use, management, and conservation of ecosystems in order to preserve microbial diversity and functioning.

  11. Microbial Ecosystems, Protection of

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Nelson, K.E.

    2014-01-01

    Synonyms Conservation of microbial diversity and ecosystem functions provided by microbes; Preservation of microbial diversity and ecosystem functions provided by microbes Definition The use, management, and conservation of ecosystems in order to preserve microbial diversity and functioning. Introdu

  12. [Response of Soil Respiration and Organic Carbon to Returning of Different Agricultural Straws and Its Mechanism].

    Science.gov (United States)

    Cao, Zhan-bo; Wang, Lei; Li, Fan; Fu, Xiao-hua; Le, Yi-quan; Wu, Ji-hua; Lu, Bing; Xu, Dian-sheng

    2016-05-15

    Soybean, maize and rice straws were selected as raw materials to study the response of the soil respiration (SR) and soil organic carbon (SOC) to returning of different straws in the Chongming Dongtan area. The results showed that all of SR, SOC and the plant biomass of the lands with returning of different straws were higher than those of the controls. The soil with soybean straw returning possessed the lowest SR and highest SOC among the three kinds of straws, meaning its higher soil organic carbon sequestration capability than corn and maize straws returning. Straw returning significantly enhanced soil dehydrogenase, β-glycosidase activities and microbial biomass, and soil dehydrogenase activity was significantly correlated with soil respiration. The dehydrogenase activity of the soil with soybean straw returning was the lowest, thus, the lowest SR and highest SOC. Soybean straw had the highest cellulose and lignin contents and the lowest N content among the three kinds of straws, resulting in its lowest biodegradability. Therefore, when soybean straw was returned to soil, it was difficult to degrade completely by soil microorganisms, thus the lowest soil microbial activity, eventually leading to the lowest SR and highest SOC.

  13. Functional soil microbial diversity across Europe estimated by EEA, MicroResp and BIOLOG

    DEFF Research Database (Denmark)

    Winding, Anne; Rutgers, Michiel; Creamer, Rachel

    Soil microorganisms are abundant and essential for the bio-geochemical processes of soil, soil quality and soil ecosystem services. All this is dependent on the actual functions the microbial communities are performing in the soil. Measuring soil respiration has for many years been the basis...... of estimating soil microbial activity. However, today several techniques are in use for determining microbial functional diversity and assessing soil biodiversity: Methods based on CO2 development by the microbes such as substrate induced respiration (SIR) on specific substrates have lead to the development...... of MicroResp and Community Level Physiological Profile (CLPP), while soil enzymatic activity are being assayed by Extracellular Enzyme Activity (EEA) based on MUF-substrates. Here we compared and contrasted the three techniques of assessing soil microbial functional diversity in a European transect...

  14. Effect of cassava mill effluent on biological activity of soil microbial community.

    Science.gov (United States)

    Igbinosa, Etinosa O

    2015-07-01

    This study assessed the effect of cassava effluent on soil microbiological characteristics and enzymatic activities were investigated in soil samples. Soil properties and heavy metal concentrations were evaluated using standard soil analytical and spectroscopic methods, respectively. The microbiological parameters measured include microbial biomass carbon, basal soil respiration, catalase, urease, dehydrogenase activities and number of culturable aerobic bacteria, fungi and actinomycetes. The pH and temperature regime vary significantly (p Soil organic carbon content gave significant positive correlations with microbial biomass carbon, basal soil respiration, catalase activity and dehydrogenase activity (r = 0.450, 0.461, 0.574 and 0.591 at p soil microbial density demonstrates a marked decrease in total culturable numbers of the different microbial groups of the polluted soil samples. Soil contamination decreased catalase, urease and dehydrogenase activities. The findings revealed that soil enzymes can be used as indices of soil contamination and bio-indicator of soil quality.

  15. Linking microbial carbon utilization with microbially-derived soil organic matter

    Science.gov (United States)

    Kallenbach, Cynthia M.; Grandy, A. Stuart

    2014-05-01

    , microbial activity and biomass, and SOM accumulation rates are monitored. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) is used to track the microbial transformation of added substrates into complex SOM and stability is measured biologically using 13C isotopes. The first 6 mo of the incubation demonstrate a significant influence of both soil mineralogy and substrate quality on microbial physiology with subsequent effects on total newly formed soil C concentrations. However, treatment differences in total C changed when only the biologically stable fraction was considered. There was an interaction between mineralogy and substrate with soil respiration, enzyme activity and microbial biomass. Py-GC/MS results show a transformation of simple substrates into chemically complex SOM, rich in proteins, lipids, and phenolics. The abundances of proteins and lipids varied however, across soil and substrate treatments, suggesting divergent SOM chemistries due to substrate quality and organo-mineral interactions. Preliminary results from this long-term study demonstrate the microbial production of complex SOM where difference in accumulation and stability are influenced by the interactions between resources and the microbial community. From this work, we can develop a better understanding of the ecological context in which SOM is formed and how altering microbial community function and resource inputs may affect the development of stable SOM.

  16. Hydrodynamic controls on respiration in the Amazon River and the importance of particle interactions on organic matter decomposition

    Science.gov (United States)

    Ward, N. D.; Sawakuchi, H. O.; Bianchi, T. S.; Gagne-Maynard, W.; Neu, V.; da Silva, D. F.; Diniz, J. E. D. M.; de Matos Valerio, A.; Cunha, A. C.; Brito, D. C.; da Silva, R.; Krusche, A. V.; Richey, J. E.; Keil, R. G.

    2016-12-01

    Microbial decomposition of terrestrial and aquatic organic matter (OM) drives an evasive CO2gas flux from the world's inland waters comparable to the amount of anthropogenic carbon absorbed by the terrestrial biosphere. However, the physical factors regulating aquatic respiration rates are not well understood and traditional respiration experiments have not satisfactorily represented the turbulent conditions that microbes experience in large rivers. We hypothesize that interactions between the OM/microbes associated with particles and their free-living/dissolved counterparts such as exoenzyme activity, cometabolism, and priming effects are a critical factor controlling respiration rates. River velocity is directly linked to the abundance of particles that remain suspended, and as such, should regulate respiration accordingly. This study examines the influence of river velocity on aquatic respiration based on experiments performed in the lower Amazon River with stationary and rotating incubation chambers equipped with integrated O2 probes to monitor O2 drawdown in real-time. For all experiments performed there was a robust positive correlation between the rate at which chambers were spun and the measured respiration rate (r2 values ranged from 0.76 to 1.00). This relationship was then used to normalize respiration rates to instantaneous measurements of river velocity across each river channel. Whereas average respiration rates measured in traditional BOD bottles could only account for 12 ± 7% of the annual average CO2 outgassing rate measured along the lower Amazon River mainstem, respiration rates based on chambers spinning at 0.22 m s-1, 0.66 m s-1, and velocity-normalized calculations could account for 64 ± 22%, 104 ± 36%, and 130 ± 62% of the CO2 outgassing rate, respectively (average river velocity along the lower Amazon River was 0.98 ± 0.42 m s-1). During each sampling campaign there was a positive correlation with river velocity and in situ CO2

  17. Competencies: A New Sector.

    Science.gov (United States)

    Brophy, Monica; Kiely, Tony

    2002-01-01

    Job analysis of managers in 42 Irish three-star hotels identified the following key management competencies and associated behavioral indicators. The results were used to develop a competency framework for management development. (Contains 29 references.) (SK)

  18. Competencies for midwifery teachers.

    Science.gov (United States)

    Thompson, Joyce E

    2002-12-01

    Saving women's lives with cost-quality effective midwifery care is based on sound pre-service and ongoing education. Effective midwifery education requires competent, caring, and compassionate teachers. In this paper, I address the basic competencies required of midwives who teach others to be midwives. These competencies are important regardless of level of student taught, type of educational programme, or number of years of midwifery experience that learners bring to the educational setting. The competencies are based on the midwifery philosophy, values and model of care. Competent midwifery teachers must be competent midwifery clinicians for their primary role is to set the boundaries of safety for each level of learner. Formal preparation for teaching, understanding how adults learn, understanding how to develop an appropriate plan for learning (curriculum), and developing competency in a variety of teaching methods for both theory and clinical practice are included in the competencies discussed in this paper.

  19. Developing mathematical modelling competence

    DEFF Research Database (Denmark)

    Blomhøj, Morten; Jensen, Tomas Højgaard

    2003-01-01

    In this paper we introduce the concept of mathematical modelling competence, by which we mean being able to carry through a whole mathematical modelling process in a certain context. Analysing the structure of this process, six sub-competences are identified. Mathematical modelling competence...... cannot be reduced to these six sub-competences, but they are necessary elements in the development of mathematical modelling competence. Experience from the development of a modelling course is used to illustrate how the different nature of the sub-competences can be used as a tool for finding...... the balance between different kinds of activities in a particular educational setting. Obstacles of social, cognitive and affective nature for the students' development of mathematical modelling competence are reported and discussed in relation to the sub-competences....

  20. Representing Microbial Processes in Environmental Reactive Transport Models

    Science.gov (United States)

    van Cappellen, P.

    2009-04-01

    Microorganisms play a key role in the biogeochemical functioning of the earth's surface and shallow subsurface. In the context of reactive transport modeling, a major challenge is to derive, parameterize, calibrate and verify mathematical expressions for microbially-mediated reactions in the environmental. This is best achieved by combining field observations, laboratory experiments, theoretical principles and modeling. Here, I will illustrate such an integrated approach for the case of microbial respiration processes in aquatic sediments. Important issues that will be covered include experimental design, model consistency and performance, as well as the bioenergetics and transient behavior of geomicrobial reaction systems.

  1. The pulsed response of soil respiration to precipitation in an African savanna ecosystem: a coupled measurement and modeling approach

    Science.gov (United States)

    Fan, Z.; Neff, J. C.; Hanan, N. P.

    2014-12-01

    Savannas cover 60% of the African continent and play an essential role in the global carbon (C) cycle. To better characterize the physical controls over soil respiration in these settings, half-hourly observations of volumetric soil-water content, temperature, and the concentration of carbon dioxide (CO2) at different soil depths were continually measured from 2005 to 2007 under trees ("sub-canopy") and between trees ("inter-canopy") in a savanna vegetation near Skukuza, Kruger National Park, South Africa. The measured soil climate and CO2 concentration data were assimilated into a process-based model that estimates the CO2 production and flux with coupled dynamics of dissolved organic C (DOC) and microbial biomass C. Our results show that temporal and spatial variations in CO2 flux were strongly influenced by precipitation and vegetation cover, with two times greater CO2 flux in the sub-canopy plots (~2421 g CO2 m-2 yr-1) than in the inter-canopy plots (~1290 g CO2 m-2 yr-1). Precipitation influenced soil respiration by changing soil temperature and moisture; however, our modeling analysis suggests that the pulsed response of soil respiration to precipitation [known as "Birch effect (BE)"] is a key control on soil fluxes at this site. At this site, BE contributed to approximately 50% and 65% of heterotrophic respiration or 20% and 39% of soil respiration in the sub-canopy and inter-canopy plots, respectively. These results suggest that pulsed response of respiration to precipitation is an important component of the C cycle of savannas and should be considered in both measurement and modeling studies of carbon exchange in similar ecosystems.

  2. Microbial activities and phosphorus cycling: An application of oxygen isotope ratios in phosphate

    Science.gov (United States)

    Stout, Lisa M.; Joshi, Sunendra R.; Kana, Todd M.; Jaisi, Deb P.

    2014-08-01

    Microorganisms carry out biochemical transformations of nutrients that make up their cells. Therefore, understanding how these nutrients are transformed or cycled in natural environments requires knowledge of microbial activity. Commonly used indicators for microbial activity typically include determining microbial respiration by O2/CO2 measurements, cell counts, and measurement of enzyme activities. However, coupled studies on nutrient cycling and microbial activity are not given enough emphasis. Here we apply phosphate oxygen isotope ratios (δ18OP) as a tool for measurement of microbial activity and compare the rate of isotope exchange with methods of measuring microbial activities that are more commonly applied in environmental studies including respiration, dehydrogenase activity, alkaline phosphatase activity, and cell counts. Our results show that different bacteria may have different strategies for P uptake, storage and release, their respiration and consequently expression of DHA and APase activities, but in general the trend of their enzyme activities are comparable. Phosphate δ18OP values correlated well with these other parameters used to measure microbial activity with the strongest linear relationships between δ18OP and CO2 evolution (r = -0.99). Even though the rate of isotope exchange for each microorganism used in this study is different, the rate per unit CO2 respiration showed one general trend, where δ18OP values move towards equilibrium while CO2 is generated. While this suggests that P cycling among microorganisms used in this study can be generalized, further research is needed to determine whether the microorganism-specific isotope exchange trend may occur in natural environments. In summary, phosphate oxygen isotope measurements may offer an alternative for use as a tracer to measure microbial activity in soils, sediments, and many other natural environments.

  3. Adjustment of Forest Ecosystem Root Respiration as Temperature Warms

    Institute of Scientific and Technical Information of China (English)

    Andrew J. Burton; Jerry M. Melillo; Serita D. Frey

    2008-01-01

    Adjustment of ecosystem root respiration to warmer climatic conditions can alter the autotrophic portion of soil respiration and influence the amount of carbon available for biomass production. We examined 44 published values of annual forest root respiration and found an increase in ecosystem root respiration with increasing mean annual temperature (MAT),but the rate of this cross-ecosystem increase (Q10 = 1.6) is less than published values for short-term responses of root respiration to temperature within ecosystems (Q10 = 2-3). When specific root respiration rates and root biomass values were examined, there was a clear trend for decreasing root metabolic capacity (respiration rate at a standard temperature) with increasing MAT. There also were tradeoffs between root metabolic capacity and root system biomass, such that there were no instances of high growing season respiration rates and high root biomass occurring together. We also examined specific root respiration rates at three soil warming experiments at Harvard Forest, USA, and found decreases in metabolic capacity for roots from the heated plots. This decline could be due to either physiological acclimation or to the effects of co-occurring drier soils on the measurement date. Regardless of the cause, these findings clearly suggest that modeling efforts that allow root respiration to increase exponentially with temperature, with Qt0 values of 2 or more, may over-predict root contributions to ecosystem CO2 efflux for future climates and underestimate the amount of C available for other uses,including net primary productivity.

  4. Building Project Competence

    DEFF Research Database (Denmark)

    Pemsel, Sofia; Wiewiora, Anna

    This research investigates the development of project competence, and particularly, three related dynamic capabilities (shifting, adapting, leveraging) that contribute to project competence development. In doing so, we make use of the emerging literature on knowledge governance and theorize how k...... of dynamic capability building promoting project competence development....

  5. Effect of heavy metals on soil microbial activity and diversity in a reclaimed mining wasteland of red soil area

    Institute of Scientific and Technical Information of China (English)

    LIAO Min; CHEN Cheng-li; HUANG Chang-yong

    2005-01-01

    The microbial biomass, basal respiration and substrate utilization pattern in copper mining wasteland of red soil area, southern China, were investigated. The results indicated that soil microflora were obviously different compared with that of the non-mine soil.Microbial biomass and basal respiration were negatively affected by the elevated heavy metal levels. Two important microbial ecophysiological parameters, namely, the ratio of microbial biomass C( Cmic )/organic C( Corg ) and metabolic quotient(qCO2 ) were closely correlated to heavy metal stress. There was a significant decrease in the Cmic/Corg ratio and an increase in the metabolic quotient with increasing metal concentration. Multivariate analysis of Biolog data for sole carbon source utilization pattern demonstrated that heavy metal pollution had a significant impact on microbial community structure and functional diversity. All the results showed that soil microbiological parameters had great potential to become the early sensitive, effective and liable indicators of the stresses or perturbations in soils of mining ecosystems.

  6. Increased microbial activity in a warmer and wetter climate enhances the risk of coastal hypoxia.

    Science.gov (United States)

    Nydahl, Anna; Panigrahi, Satya; Wikner, Johan

    2013-08-01

    The coastal zone is the most productive area of the marine environment and the area that is most exposed to environmental drivers associated with human pressures in a watershed. In dark bottle incubation experiments, we investigated the short-term interactive effects of changes in salinity, temperature and riverine dissolved organic matter (rDOM) on microbial respiration, growth and abundance in an estuarine community. An interaction effect was found for bacterial growth, where the assimilation of rDOM increased at higher salinities. A 3 °C rise in the temperature had a positive effect on microbial respiration. A higher concentration of DOM consistently enhanced respiration and bacterial abundance, while an increase in temperature reduced bacterial abundance. The latter result was most likely caused by a positive interaction effect of temperature, salinity and rDOM on the abundance of bacterivorous flagellates. Elevated temperature and precipitation, causing increased discharges of rDOM and an associated lowered salinity, will therefore primarily promote bacterial respiration, growth and bacterivore abundance. Our results suggest a positive net outcome for microbial activity under the projected climate change, driven by different, partially interacting environmental factors. Thus, hypoxia in coastal zones may increase due to enhanced respiration caused by higher temperatures and rDOM discharge acting synergistically.

  7. Decreased carbon limitation of litter respiration in a mortality-affected piñon–juniper woodland

    Directory of Open Access Journals (Sweden)

    E. Berryman

    2013-03-01

    Full Text Available Microbial respiration depends on microclimatic variables and carbon (C substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting piñon–juniper ecosystems in southwestern North America, may affect C substrate availability in several ways, for example, via litterfall pulses and loss of root exudation. To determine piñon mortality effects on C and water limitation of microbial respiration, we applied field amendments (sucrose and water to two piñon–juniper sites in central New Mexico, USA: one with a recent (2 flux on the girdled site and a non-significant increase on the control. We speculate that the reduction may have been driven by water-induced carbonate dissolution, which serves as a sink for CO2 and would reduce the net flux. Widespread piñon mortality may decrease labile C limitation of litter respiration, at least during the first growing season following mortality.

  8. Monitoring the performances of a real scale municipal solid waste composting and a biodrying facility using respiration activity indices.

    Science.gov (United States)

    Evangelou, Alexandros; Gerassimidou, Spyridoula; Mavrakis, Nikitas; Komilis, Dimitrios

    2016-05-01

    Objective of the work was to monitor two full-scale commingled municipal solid waste (MSW) mechanical and biological pretreatment (MBT) facilities in Greece, namely a biodrying and a composting facility. Monitoring data from a 1.5-year sampling period is presented, whilst microbial respiration indices were used to monitor the decomposition process and the stability status of the wastes in both facilities during the process. Results showed that in the composting facility, the organic matter reduced by 35 % after 8 weeks of combined composting/curing. Material exiting the biocells had a moisture content of less than 30 % (wb) indicating a moisture limitation during the active composting process. The static respiration indexes indicated that some stabilization occurred during the process, but the final material could not be characterized as stable compost. In the biodrying facility, the initial and final moisture contents were 50 % and less than 20 % wb, respectively, and the biodrying index was equal to 4.1 indicating effective biodrying. Lower heating values at the inlet and outlet were approximately 5.5 and 10 MJ/wet kg, respectively. The organic matter was reduced by 20 % during the process and specifically from a range of 63-77 % dw (inlet) to a range of 61-70 % dw. A significant respiration activity reduction was observed for some of the biodrying samples. A statistically significant correlation among all three respiration activity indices was recorded, with the two oxygen related activity indices (CRI7 and SRI24) observing the highest correlation.

  9. Tillage Effects on Soil Properties & Respiration

    Science.gov (United States)

    Rusu, Teodor; Bogdan, Ileana; Moraru, Paula; Pop, Adrian; Duda, Bogdan; Cacovean, Horea; Coste, Camelia

    2015-04-01

    Soil tillage systems can be able to influence soil compaction, water dynamics, soil temperature and soil structural condition. These processes can be expressed as changes of soil microbiological activity, soil respiration and sustainability of agriculture. Objectives of this study were: 1) to assess the effects of tillage systems (Conventional System-CS, Minimum Tillage-MT, No-Tillage-NT) on soil compaction, soil temperature, soil moisture and soil respiration and 2) to establish the relationship that exists in changing soil properties. Three treatments were installed: CS-plough + disc; MT-paraplow + rotary grape; NT-direct sowing. The study was conducted on an Argic-Stagnic Faeoziom. The MT and NT applications reduce or completely eliminate the soil mobilization, due to this, soil is compacted in the first year of application. The degree of compaction is directly related to soil type and its state of degradation. The state of soil compaction diminished over time, tending toward a specific type of soil density. Soil moisture was higher in NT and MT at the time of sowing and in the early stages of vegetation and differences diminished over time. Moisture determinations showed statistically significant differences. The MT and NT applications reduced the thermal amplitude in the first 15 cm of soil depth and increased the soil temperature by 0.5-2.20C. The determinations confirm the effect of soil tillage system on soil respiration; the daily average was lower at NT (315-1914 mmoli m-2s-1) and followed by MT (318-2395 mmoli m-2s-1) and is higher in the CS (321-2480 mmol m-2s-1). Comparing with CS, all the two conservation tillage measures decreased soil respiration, with the best effects of no-tillage. An exceeding amount of CO2 produced in the soil and released into the atmosphere, resulting from aerobic processes of mineralization of organic matter (excessive loosening) is considered to be not only a way of increasing the CO2 in the atmosphere, but also a loss of

  10. Filter casing for respirators. Filtergehaeuse fuer Atemschutzmasken

    Energy Technology Data Exchange (ETDEWEB)

    Pantaleon-Stemberg, G.

    1987-12-16

    A filter casing for respirators, in which filter inserts are held exchangeably by means of a holder engaging into the wall of the casing, is improved in that filter inserts of different height and in various combinations can be fixed in it with the same holder. For that purpose the holder is designed as a socket which is open at both ends and can be fixed to the inside wall of the filter casing and is axially displaceable and envelops the filter insert, the end circumference of said socket having a fixing device projecting inwards.

  11. Bicarbonate alters cellular responses in respiration assays.

    Science.gov (United States)

    Krycer, James R; Fisher-Wellman, Kelsey H; Fazakerley, Daniel J; Muoio, Deborah M; James, David E

    2017-08-05

    Metabolic assay buffers often omit bicarbonate, which is susceptible to alkalinisation in an open environment. Here, we assessed the effect of including bicarbonate in respirometry experiments. By supplementing HEPES-buffered media with low concentrations of bicarbonate, we found increased respiration in adipocytes and hepatocytes, but not myotubes. This was observed across multiple respirometry platforms and was independent of effects on enhanced insulin sensitivity, pH drift, or mitochondrial function. Permeabilised cell experiments suggest that bicarbonate increases substrate availability, likely by acting as a cofactor for carboxylase enzymes. This emphasises the importance of buffer choice in experimental biology. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Evidence of clinical competence.

    Science.gov (United States)

    Lejonqvist, Gun-Britt; Eriksson, Katie; Meretoja, Riitta

    2012-06-01

    This cross-sectional research used a qualitative questionnaire to explore clinical competence in nursing. The aim was to look for evidence of how clinical competence showed itself in practice. In the research, the views from both education and working life are combined to broadly explore and describe clinical competence from the perspective of students, clinical preceptors and teachers. The questions were formulated on how clinical competence is characterised and experienced, what contributes to it and how it is maintained, and on the relation between clinical competence and evidence-based care. The answers were analysed by inductive content analysis. The results showed that clinical competence in practice is encountering, knowing, performing, maturing and improving. Clinical competence is an ongoing process, rather than a state and manifests itself in an ontological and a contextual dimension.

  13. Evaluation of Five Decontamination Methods for Filtering Facepiece Respirators

    OpenAIRE

    Viscusi, Dennis J.; Bergman, Michael S.; Eimer, Benjamin C.; Ronald E. Shaffer

    2009-01-01

    Concerns have been raised regarding the availability of National Institute for Occupational Safety and Health (NIOSH)-certified N95 filtering facepiece respirators (FFRs) during an influenza pandemic. One possible strategy to mitigate a respirator shortage is to reuse FFRs following a biological decontamination process to render infectious material on the FFR inactive. However, little data exist on the effects of decontamination methods on respirator integrity and performance. This study eval...

  14. A survey of respirators usage for airborne chemicals in Korea.

    Science.gov (United States)

    Han, Don-Hee; Kang, Min-Sun

    2009-10-01

    A questionnaire survey was undertaken to identify the current status of respirator usage in manufacturing work environments subject to gas/vapor chemicals exposure in Korea and to suggest improvements to enhance the effectiveness of respirator usage. The number of target companies included 17 big companies, 110 small & mid-size companies, and 5 foreign companies, and the number of respondents included 601 workers and 69 persons in charge of respirators (PCR). The results explained clearly that respirator programs in practice were extremely poor in small & mid-sized companies. The findings indicated that the selection of respirators was not appropriate. Quarter mask including filtering facepiece was the most common facepiece form for respirator and was worn by sixty-four percent. Not a little proportion of respondents (33%) complained about the fit: faceseal leakage between the face and facepiece. A filtering facepiece with carbon fiber filter was used as a substitution for a gas/vapor respirator. Another result was that the PCR respondents' perception of the administration of respirators was very low. The results of this survey suggest that regal enforcement of respiratory protection programs should be established in Korea. On the basis of these findings, respiratory protection programs should include respirator selection, maintenance, training, and fit testing.

  15. [The development of a respiration and temperature monitor].

    Science.gov (United States)

    Du, X; Wu, B; Liu, Y; He, Q; Xiao, J

    2001-12-01

    This paper introduces the design of a monitoring system to measure the respiration and temperature of a body with an 8Xc196 single-chip microcomputer. This system can measure and display the respiration wave, respiration frequency and the body temperature in real-time with a liquid crystal display (LCD) and give an alarm when the parameters are beyond the normal scope. In addition, this device can provide a 24 hours trend graph of the respiration frequency and the body temperature parameters measured. Data can also be exchanged through serial communication interfaces (RS232) between the PC and the monitor.

  16. Stability of soil microbial structure and activity depends on microbial diversity.

    Science.gov (United States)

    Tardy, Vincent; Mathieu, Olivier; Lévêque, Jean; Terrat, Sébastien; Chabbi, Abad; Lemanceau, Philippe; Ranjard, Lionel; Maron, Pierre-Alain

    2014-04-01

    Despite the central role of microbes in soil processes, empirical evidence concerning the effect of their diversity on soil stability remains controversial. Here, we addressed the ecological insurance hypothesis by examining the stability of microbial communities along a gradient of soil microbial diversity in response to mercury pollution and heat stress. Diversity was manipulated by dilution extinction approach. Structural and functional stabilities of microbial communities were assessed from patterns of genetic structure and soil respiration after the stress. Dilution led to the establishment of a consistent diversity gradient, as revealed by 454 sequencing of ribosomal genes. Diversity stability was enhanced in species-rich communities whatever the stress whereas functional stability was improved with increasing diversity after heat stress, but not after mercury pollution. This discrepancy implies that the relevance of ecological insurance for soil microbial communities might depend on the type of stress. Our results also suggest that the significance of microbial diversity for soil functional stability might increase with available soil resources. This could have strong repercussions in the current 'global changes' context because it suggests that the combined increased frequencies of extreme climatic events, nutrient loading and biotic exploitation may amplify the functional consequences of diversity decrease.

  17. Recovery of microbial community structure and functioning after wildfire in semi-arid environments: optimising methods for monitoring and assessment

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Martini, Dylan; Erickson, Todd; Merritt, David; Dixon, Kingsley

    2015-04-01

    Introduction In semi-arid areas such as northern Western Australia, wildfires are a natural part of the environment and many ecosystems in these landscapes have evolved and developed a strong relationship with fire. Soil microbial communities play a crucial role in ecosystem processes by regulating the cycling of nutrients via decomposition, mineralization, and immobilization processes. Thus, the structure (e.g. soil microbial biomass) and functioning (e.g. soil microbial activity) of microbial communities, as well as their changes after ecosystem disturbance, can be useful indicators of soil quality and health recovery. In this research, we assess the impacts of fire on soil microbial communities and their recovery in a biodiverse semi-arid environment of Western Australia (Pilbara region). New methods for determining soil microbial respiration as an indicator of microbial activity and soil health are also tested. Methodology Soil samples were collected from 10 similar ecosystems in the Pilbara with analogous native vegetation, but differing levels of post-fire disturbance (i.e. 3 months, 1 year, 5, 7 and 14 years after wildfire). Soil microbial activity was measured with the Solvita test which determines soil microbial respiration rate based on the measurement of the CO2 burst of a dry soil after it is moistened. Soils were dried and re-wetted and a CO2 probe was inserted before incubation at constant conditions of 25°C during 24 h. Measurements were taken with a digital mini spectrometer. Microbial (bacteria and fungi) biomass and community composition were measured by phospholipid fatty acid analysis (PLFA). Results Immediately after the fire (i.e. 3 months), soil microbial activity and microbial biomass are similar to 14 years 'undisturbed' levels (53.18±3.68 ppm CO2-CO and 14.07±0.65 mg kg-1, respectively). However, after the first year post-fire, with larger plant productivity, microbial biomass and microbial activity increase rapidly, peaking after 5

  18. Microbial-electrochemical bioremediation and detoxification of dibenzothiophene-polluted soil.

    Science.gov (United States)

    Rodrigo, Jose; Boltes, Karina; Esteve-Nuñez, Abraham

    2014-04-01

    Bioremediation is a relatively efficient and cost-effective technology for treating polluted soils. However, the availability of suitable electron acceptors to sustain microbial respiration can reduce the microbial activity. This work aims to evaluate the impact of burying electrically conductive electron acceptors in soil for enhancing the removal of dibenzothiophene (DBT) by native electrogenic microbes. Although this novel approach is based on the use of a microbial electrochemical technology as microbial fuel cells, our goal is not to harvest energy but to maximize bioremediation, so we concluded to name the device as Microbial Electroremediating Cell (MERC). Our results proved that stimulating the microbial electrogenic metabolism, DBT removal was enhanced by more than 3-fold compared to the natural attenuation. On top of that, ecotoxicological test using green algae confirms a decrease of 50% in the toxicity of the treated soil during incubation in MERC, in contrast to the unaltered values detected under natural conditions.

  19. Role of bicarbonate as a pH buffer and electron sink in microbial dechlorination of chloroethenes

    Directory of Open Access Journals (Sweden)

    Delgado Anca G

    2012-09-01

    Full Text Available Abstract Background Buffering to achieve pH control is crucial for successful trichloroethene (TCE anaerobic bioremediation. Bicarbonate (HCO3− is the natural buffer in groundwater and the buffer of choice in the laboratory and at contaminated sites undergoing biological treatment with organohalide respiring microorganisms. However, HCO3− also serves as the electron acceptor for hydrogenotrophic methanogens and hydrogenotrophic homoacetogens, two microbial groups competing with organohalide respirers for hydrogen (H2. We studied the effect of HCO3− as a buffering agent and the effect of HCO3−-consuming reactions in a range of concentrations (2.5-30 mM with an initial pH of 7.5 in H2-fed TCE reductively dechlorinating communities containing Dehalococcoides, hydrogenotrophic methanogens, and hydrogenotrophic homoacetogens. Results Rate differences in TCE dechlorination were observed as a result of added varying HCO3− concentrations due to H2-fed electrons channeled towards methanogenesis and homoacetogenesis and pH increases (up to 8.7 from biological HCO3− consumption. Significantly faster dechlorination rates were noted at all HCO3− concentrations tested when the pH buffering was improved by providing 4-(2-hydroxyethyl-1-piperazineethanesulfonic acid (HEPES as an additional buffer. Electron balances and quantitative PCR revealed that methanogenesis was the main electron sink when the initial HCO3− concentrations were 2.5 and 5 mM, while homoacetogenesis was the dominant process and sink when 10 and 30 mM HCO3− were provided initially. Conclusions Our study reveals that HCO3− is an important variable for bioremediation of chloroethenes as it has a prominent role as an electron acceptor for methanogenesis and homoacetogenesis. It also illustrates the changes in rates and extent of reductive dechlorination resulting from the combined effect of electron donor competition stimulated by HCO3− and the changes in pH exerted by

  20. Central cholinergic regulation of respiration: nicotinic receptors

    Institute of Scientific and Technical Information of China (English)

    Xuesi M SHAO; Jack L FELDMAN

    2009-01-01

    Nicotinic acetylcholine receptors (nAChRs) are expressed in brainstem and spinal cord regions involved in the control of breathing. These receptors mediate central cholinergic regulation of respiration and effects of the exogenous ligand nicotine on respiratory pattern. Activation of a4* nAChRs in the preBotzinger Complex (preBotC), an essential site for normal respiratory rhythm generation in mammals, modulates excitatory glutamatergic neurotransmission and depolarizes preBotC inspiratory neurons, leading to increases in respiratory frequency. nAChRs are also present in motor nuclei innervating respiratory muscles. Activation of post- and/or extra-synaptic a4* nAChRs on hypoglossal (XII) motoneurons depolarizes these neurons, potentiating tonic and respiratory-related rhythmic activity. As perinatal nicotine exposure may contribute to the pathogenesis of sudden infant death syndrome (SIDS), we discuss the effects of perinatal nicotine exposure on development of the cholinergic and other neurotransmitter systems involved in control of breathing. Advances in understanding of the mechanisms underlying central cholinergic/nicotinic modulation of respiration provide a pharmacological basis for exploiting nAChRs as therapeutic targets for neurological disorders related to neural control of breathing such as sleep apnea and SIDS.

  1. Underwater breathing: the mechanics of plastron respiration

    Science.gov (United States)

    Flynn, M. R.; Bush, John W. M.

    The rough, hairy surfaces of many insects and spiders serve to render them water-repellent; consequently, when submerged, many are able to survive by virtue of a thin air layer trapped along their exteriors. The diffusion of dissolved oxygen from the ambient water may allow this layer to function as a respiratory bubble or , and so enable certain species to remain underwater indefinitely. Maintenance of the plastron requires that the curvature pressure balance the pressure difference between the plastron and ambient. Moreover, viable plastrons must be of sufficient area to accommodate the interfacial exchange of O2 and CO2 necessary to meet metabolic demands. By coupling the bubble mechanics, surface and gas-phase chemistry, we enumerate criteria for plastron viability and thereby deduce the range of environmental conditions and dive depths over which plastron breathers can survive. The influence of an external flow on plastron breathing is also examined. Dynamic pressure may become significant for respiration in fast-flowing, shallow and well-aerated streams. Moreover, flow effects are generally significant because they sharpen chemical gradients and so enhance mass transfer across the plastron interface. Modelling this process provides a rationale for the ventilation movements documented in the biology literature, whereby arthropods enhance plastron respiration by flapping their limbs or antennae. Biomimetic implications of our results are discussed.

  2. Invasion of a semi-arid shrubland by annual grasses increases autotrophic and heterotrophic soil respiration rates due to altered soil moisture and temperature patterns

    Science.gov (United States)

    Mauritz, M.; Hale, I.; Lipson, D.

    2010-12-01

    Shrub grassland conversions are a globally occurring phenomenon altering habitat structure, quality and nutrient cycling. Grasses and shrubs differ in their above and belowground biomass allocation, root architecture, phenology, litter quality and quantity. Conversion affects soil microbial communities, soil moisture and temperature and carbon (C) allocation patterns. However, the effect of conversion on C storage is regionally variable and there is no consistent direction of change. In Southern California invasion by annual grasses is a major threat to native shrub communities and it has been proposed that grass invasion increases NPP and ecosystem C storage (Wolkovich et al, 2009). In order to better understand how this shrub grassland conversion changes ecosystem C storage it is important to understand the partitioning of soil respiration into autotrophic and heterotrophic components. Respiration was measured in plots under shrubs and grasses from February when it was cold and wet to July when it was hot and dry, capturing seasonal transitions in temperature and water availability. Roots were excluded under shrubs and grasses with root exclusion cores to quantify heterotrophic respiration. Using total soil respiration (Rt) = autotrophic respiration (root) (Ra)+ heterotrophic respiration (microbial) (Rh) the components contributing to total soil respiration can be evaluated. Respiration, soil moisture and temperature were measured daily at four hour intervals using Licor 8100 automated chamber measurements. Throughout the measurement period, Rt under grasses exceeded Rt under shrubs. Higher Rt levels under grasses were mainly due to higher Ra in grasses rather than changes in Rh. On average grass Ra was almost double shrub Ra. Higher grass respiration levels are partially explained by differences in soil moisture and temperature between shrubs and grasses. Respiration rates responded similarly to seasonal transitions regardless of treatment although Ra had a much

  3. The contribution of root respiration of Pinus koraiensis seedlings to total soil respiration under elevated CO2 concentrations

    Institute of Scientific and Technical Information of China (English)

    LIUYing; HANShi-jie; LIXue-feng; ZHOUYu-mei; ZHANGJun-hui; JIAXia

    2004-01-01

    The impacts of elevated atmospheric CO2 concentrations (500 IJmol.mol-land 700 μmol.mo1-1) on total soil respiration and the contribution of root respiration of Pinus koraiensis seedlings were investigated from May to October in 2003 at the Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences, Jilin Province, China. After four growing seasons in top-open chambers exposed to elevated CO2, the total soil respiration and roots respiration of Pinus koraiensis seedlings were measured by a LI-6400-09 soil CO2 flux chamber. Three PVC cylinders in each chamber were inserted about 30 cm into the soil instantaneously to terminate the supply of current photosynthates from the tree canopy to roots for separating the root respiration from total soil respiration. Soil respirations both inside and outside of the cylinders were measured on June 16, August 20 and October 8, respectively. The results indicated that: there was a marked diurnal change in air temperature and soil temperature at depth of 5 cm on June 16, the maximum of soil temperature at depth of 5 cm laggedb ehind that of air temperature, no differences in temperature between treatments were found (P>0.05). The total soil respiration and soil respiration with roots severed showed strong diurnal and seasonal patterns. There was marked difference in total soil respiration and soil respiration with roots severed between treatments (P<0.01); Mean total soil respiration and contribution of root under different treatments were 3.26, 4.78 and 1.47 μmol .m-2.s-1, 11.5%, 43.1% and 27.9% on June 16, August 20 and October 8. respectivelv.

  4. Can we distinguish autotrophic respiration from heterotrophic respiration in a field site using high temporal resolution CO2 flux measurements?

    Science.gov (United States)

    Biro, Beatrice; Berger, Sina; Praetzel, Leandra; Blodau, Christian

    2016-04-01

    The processes behind C-cycling in peatlands are important to understand for assessing the vulnerability of peatlands as carbon sinks under changing climate conditions. Especially boreal peatlands are likely to underlie strong alterations in the future. It is expected that C-pools that are directly influenced by vegetation and water table fluctuations can be easily destabilized. The CO2 efflux through respiration underlies autotrophic and heterotrophic processes that show different feedbacks on changing environmental conditions. In order to understand the respiration fluxes better for more accurate modelling and prognoses, the determination of the relative importance of different respiration sources is necessary. Earlier studies used e.g. exfoliation experiments, incubation experiments or modelling approaches to estimate the different respiration sources for the total ecosystem respiration (Reco). To further the understanding in this topic, I want to distinguish autotrophic and heterotrophic respiration using high temporal resolution measurements. The study site was selected along a hydrological gradient in a peatland in southern Ontario (Canada) and measurements were conducted from May to September 2015 once per month. Environmental controls (water table, soil temperature and soil moisture) that effect the respiration sources were recorded. In my study I used a Li-COR 6400XT and a Los Gatos greenhouse gas analyzer (GGA). Reco was determined by chamber flux measurements with the GGA, while simultaneously CO2 respiration measurements on different vegetation compartments like roots, leaves and mosses were conducted using the Li-COR 6400XT. The difference between Reco and autotrophic respiration equals heterotrophic respiration. After the measurements, the vegetation plots were harvested and separated for all compartments (leaves, roots, mosses, soil organic matter), dried and weighed. The weighted respiration rates from all vegetation compartments sum up to

  5. Characterisation of microbial biocoenosis in vertical subsurface flow constructed wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Tietz, Alexandra [Institute of Sanitary Engineering and Water Pollution Control, BOKU - University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna (Austria)]. E-mail: alexandra.tietz@boku.ac.at; Kirschner, Alexander [Clinical Institute for Hygiene and Medical Microbiology, Department for Water Hygiene - Medical University of Vienna, Kinderspitalgasse 15, A-1090 Vienna (Austria); Langergraber, Guenter [Institute of Sanitary Engineering and Water Pollution Control, BOKU - University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna (Austria); Sleytr, Kirsten [Institute of Sanitary Engineering and Water Pollution Control, BOKU - University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna (Austria); Haberl, Raimund [Institute of Sanitary Engineering and Water Pollution Control, BOKU - University of Natural Resources and Applied Life Sciences, Vienna, Muthgasse 18, A-1190 Vienna (Austria)

    2007-07-15

    In this study a quantitative description of the microbial biocoenosis in subsurface vertical flow constructed wetlands fed with municipal wastewater was carried out. Three different methods (substrate induced respiration, ATP measurement and fumigation-extraction) were applied to measure the microbial biomass at different depths of planted and unplanted systems. Additionally, bacterial biomass was determined by epifluorescence microscopy and productivity was measured via {sup 14}C leucine incorporation into bacterial biomass. All methods showed that > 50% of microbial biomass and bacterial activity could be found in the first cm and about 95% in the first 10 cm of the filter layer. Bacterial biomass in the first 10 cm of the filter body accounted only for 16-19% of the total microbial biomass. Whether fungi or methodical uncertainties are mainly responsible for the difference between microbial and bacterial biomass remains to be examined. A comparison between the purification performance of planted and unplanted pilot-scale subsurface vertical flow constructed wetlands (PSCWs) showed no significant difference with the exception of the reduction of enterococci. The microbial biomass in all depths of the filter body was also not different in planted and unplanted systems. Compared with data from soils the microbial biomass in the PSCWs was high, although the specific surface area of the used sandy filter material available for biofilm growth was lower, especially in the beginning of the set-up of the PSCWs, due to missing clay and silt fraction.

  6. Nitrogen Addition Altered the Effect of Belowground C Allocation on Soil Respiration in a Subtropical Forest.

    Directory of Open Access Journals (Sweden)

    Tongxin He

    Full Text Available The availabilities of carbon (C and nitrogen (N in soil play an important role in soil carbon dioxide (CO2 emission. However, the variation in the soil respiration (Rs and response of microbial community to the combined changes in belowground C and N inputs in forest ecosystems are not yet fully understood. Stem girdling and N addition were performed in this study to evaluate the effects of C supply and N availability on Rs and soil microbial community in a subtropical forest. The trees were girdled on 1 July 2012. Rs was monitored from July 2012 to November 2013, and soil microbial community composition was also examined by phospholipid fatty acids (PLFAs 1 year after girdling. Results showed that Rs decreased by 40.5% with girdling alone, but N addition only did not change Rs. Interestingly, Rs decreased by 62.7% under the girdling with N addition treatment. The reducing effect of girdling and N addition on Rs differed between dormant and growing seasons. Girdling alone reduced Rs by 33.9% in the dormant season and 54.8% in the growing season compared with the control. By contrast, girdling with N addition decreased Rs by 59.5% in the dormant season and 65.4% in the growing season. Girdling and N addition significantly decreased the total and bacterial PLFAs. Moreover, the effect of N addition was greater than girdling. Both girdling and N addition treatments separated the microbial groups on the basis of the first principal component through principal component analysis compared with control. This indicated that girdling and N addition changed the soil microbial community composition. However, the effect of girdling with N addition treatment separated the microbial groups on the basis of the second principal component compared to N addition treatment, which suggested N addition altered the effect of girdling on soil microbial community composition. These results suggest that the increase in soil N availability by N deposition alters the

  7. Microbial hotspots and hot moments in soil

    Science.gov (United States)

    Kuzyakov, Yakov; Blagodatskaya, Evgenia

    2015-04-01

    Soils are the most heterogeneous parts of the biosphere, with an extremely high differentiation of properties and processes within nano- to macroscales. The spatial and temporal heterogeneity of input of labile organics by plants creates microbial hotspots over short periods of time - the hot moments. We define microbial hotspots as small soil volumes with much faster process rates and much more intensive interactions compared to the average soil conditions. Such hotspots are found in the rhizosphere, detritusphere, biopores (including drilosphere) and on aggregate surfaces, but hotspots are frequently of mixed origin. Hot moments are short-term events or sequences of events inducing accelerated process rates as compared to the averaged rates. Thus, hotspots and hot moments are defined by dynamic characteristics, i.e. by process rates. For this hotspot concept we extensively reviewed and examined the localization and size of hotspots, spatial distribution and visualization approaches, transport of labile C to and from hotspots, lifetime and process intensities, with a special focus on process rates and microbial activities. The fraction of active microorganisms in hotspots is 2-20 times higher than in the bulk soil, and their specific activities (i.e. respiration, microbial growth, mineralization potential, enzyme activities, RNA/DNA ratio) may also be much higher. The duration of hot moments in the rhizosphere is limited and is controlled by the length of the input of labile organics. It can last a few hours up to a few days. In the detritusphere, however, the duration of hot moments is regulated by the output - by decomposition rates of litter - and lasts for weeks and months. Hot moments induce succession in microbial communities and intense intra- and interspecific competition affecting C use efficiency, microbial growth and turnover. The faster turnover and lower C use efficiency in hotspots counterbalances the high C inputs, leading to the absence of strong

  8. Lymphocyte respiration in children with Trisomy 21

    Directory of Open Access Journals (Sweden)

    Aburawi Elhadi H

    2012-12-01

    Full Text Available Abstract Background This study measured lymphocyte mitochondrial O2 consumption (cellular respiration in children with trisomy 21. Methods Peripheral blood mononuclear cells were isolated from whole blood of trisomy 21 and control children and these cells were immediately used to measure cellular respiration rate. [O2] was determined as a function of time from the phosphorescence decay rates (1/τ of Pd (II-meso-tetra-(4-sulfonatophenyl-tetrabenzoporphyrin. In sealed vials containing lymphocytes and glucose as a respiratory substrate, [O2] declined linearly with time, confirming the zero-order kinetics of O2 conversion to H2O by cytochrome oxidase. The rate of respiration (k, in μM O2 min-1, thus, was the negative of the slope of [O2] vs. time. Cyanide inhibited O2 consumption, confirming that oxidation occurred in the mitochondrial respiratory chain. Results For control children (age = 8.8 ± 5.6 years, n = 26, the mean (± SD value of kc (in μM O2 per min per 107 cells was 1.36 ± 0.79 (coefficient of variation, Cv = 58%; median = 1.17; range = 0.60 to 3.12; -2SD = 0.61. For children with trisomy 21 (age = 7.2 ± 4.6 years, n = 26, the values of kc were 0.82 ± 0.62 (Cv = 76%; median = 0.60; range = 0.20 to 2.80, pp6.1 mU/L. Fourteen of 26 (54% children with trisomy 21 had kc values of 0.20 to 0.60 (i.e., kc positively correlated with body-mass index (BMI, R >0.302, serum creatinine (R >0.507, blood urea nitrogen (BUN, R >0.535 and albumin (R >0.446. Conclusions Children with trisomy 21 in this study have reduced lymphocyte bioenergetics. The clinical importance of this finding requires further studies.

  9. Observing Mean Annual Mediterranean Maquis Ecosystem Respiration

    Science.gov (United States)

    Marras, S.; Bellucco, V.; Mereu, S.; Sirca, C.; Spano, D.

    2014-12-01

    In semi arid ecosystems, extremely low Soil Water Content (SWC) values may limit ecosystem respiration (Reco) to the point of hiding the typical exponential response of respiration to temperature. This work is aimed to understand and model the Reco of an evergreen Mediterranean maquis ecosystem and to estimate the contribution of soil CO2 efflux to Reco. The selected site is located in the center of the Mediterranean sea in Sardinia (Italy). Mean annual precipitation is 588 mm and mean annual temperature is 15.9 °C. Vegetation cover is heterogeneous: 70% covered by shrubs and 30% of bare soil. Net Ecosystem Exchange (NEE) is monitored with an Eddy Covariance (EC) tower since April 2004. Soil collars were placed underneath the dominant species (Juniperus phoenicea and Pistacia lentiscus) and over the bare soil. Soil CO2 efflux was measured once a month since April 2012. Soil temperature and SWC were monitored continuously at 5 cm depth in 4 different positions close to the soil collars. Six years of EC measurements (2005-2010) and two years of soil CO2 efflux (2012-2013) measurements were analysed. Reco was estimated from the measured EC fluxes at night after filtering for adequate turbulence (u* > 1.5). Reco measurements were then binned into 1°C intervals and median values were first fitted using the Locally Estimated Scatterplot Smoothing (LOESS) method (to determine the dominant trend of the experimental curve) Reco shows an exponential increase with air and soil temperature, until SWC measured at 0.2 m depth remains above 19% vol. Secondly, the coefficients of the selected Lloyd and Taylor (1994) were estimated through the nonlinear least square (nls) method: Rref (ecosystem respiration rate at a reference temperature of 10 °C was equal to 1.65 μmol m-2 s-1 and E0 (activation energy parameter that determines the temperature sensitivity) was equal to 322.46. In addition, bare and drier soils show a reduced response of measured CO2 efflux to increasing

  10. Experimental methods in aquatic respirometry: the importance of mixing devices and accounting for background respiration.

    Science.gov (United States)

    Rodgers, G G; Tenzing, P; Clark, T D

    2016-01-01

    In light of an increasing trend in fish biology towards using static respirometry techniques without the inclusion of a mixing mechanism and without accurately accounting for the influence of microbial (background) respiration, this paper quantifies the effect of these approaches on the oxygen consumption rates (ṀO2 ) measured from juvenile barramundi Lates calcarifer (mean ± s.e. mass = 20·31 ± 0·81 g) and adult spiny chromis damselfish Acanthochromis polyacanthus (22·03 ± 2·53 g). Background respiration changed consistently and in a sigmoidal manner over time in the treatment with a mixing device (inline recirculation pump), whereas attempts to measure background respiration in the non-mixed treatment yielded highly variable estimates of ṀO2 that were probably artefacts due to the lack of water movement over the oxygen sensor during measurement periods. This had clear consequences when accounting for background respiration in the calculations of fish ṀO2 . Exclusion of a mixing device caused a significantly lower estimate of ṀO2 in both species and reduced the capacity to detect differences between individuals as well as differences within an individual over time. There was evidence to suggest that the magnitude of these effects was dependent on the spontaneous activity levels of the fish, as the difference between mixed and non-mixed treatments was more pronounced for L. calcarifer (sedentary) than for A. polyacanthus (more spontaneously active). It is clear that respirometry set-ups for sedentary species must contain a mixing device to prevent oxygen stratification inside the respirometer. While more active species may provide a higher level of water mixing during respirometry measurements and theoretically reduce the need for a mixing device, the level of mixing cannot be quantified and may change with diurnal cycles in activity. To ensure consistency across studies without relying on fish activity levels, and to enable accurate assessments of

  11. Temperature sensitivity of soil respiration: Synthetic effects of nitrogen and phosphorus fertilization on Chinese Loess Plateau.

    Science.gov (United States)

    Wang, Rui; Sun, Qiqi; Wang, Ying; Liu, Qingfang; Du, Lanlan; Zhao, Man; Gao, Xin; Hu, Yaxian; Guo, Shengli

    2017-01-01

    Nitrogen (N) and phosphorus (P) fertilization has the potential to alter soil respiration temperature sensitivity (Q10) by changing soil biochemical and crop physiological process. A four-year field experiment was conducted to determine how Q10 responded to these biochemical and physiological changes in rain-fed agro-ecosystems on the semi-arid Loess Plateau. Soil respiration, as well as biotic and abiotic factors were measured in winter wheat (Triticum aestivum L.), with three fertilization treatments: (no fertilization (CK), 160kgNhm(-1) (N), and 160kgNha(-1) with 39kgPha(-1) (N+P). Mean annual soil respiration rate (calculated by averaging the four years) in the N treatment and N+P treatment was 18% and 48% higher than that in the CK treatment, respectively; and it was increased by 26% (14%-48%) in the N+P treatment as compared with that in the N treatment. The decrease of Q10 in the N and N+P treatments against the CK treatment was not stable for each year, ranging from 0.01 to 0.28. The maximum decrease of Q10 in the N and N+P treatments was 10% and 15% in 2014-2015, while in other years the decrease of Q10 was numerical but not significant. Soil microbial biomass carbon (SMBC) was increased by 10% and 50%, dissolved organic carbon (DOC) was increased by 6% and 21%, and photosynthesis rate was increased ranging from 6% to 33% with N and N+P fertilization. The relative abundance of Acidobacteria, Actinobacteria and Chloroflexi were significantly higher by 32.9%-54.1% in N addition soils (N and N+P) compared to CK treatment, whereas additional P application into soils increased the relative abundance of the family Micrococcaceae, Nocardioidaceae and Chitinophagaceae. Soil respiration was positively related to SMBC, DOC and photosynthesis rate (paffect soil respiration and temperature sensitivity differently. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Seasonal Development of Microbial Activity in Soils of Northern Norway

    Institute of Scientific and Technical Information of China (English)

    M. B(O)LTER; N. SOETHE; R. HORN; C. UHLIG

    2005-01-01

    Seasonal development of soil microbial activity and bacterial biomass in sub-polar regions was investigated to determine the impacts of biotic and abiotic factors, such as organic matter content, temperature and moisture. The study was performed during spring thaw from three cultivated meadows and two non-cultivated forest sites near Alta, in northern Norway. Samples from all five sites showed increasing respiration rates directly after the spring thaw with soil respiration activity best related to soil organic matter content. However, distributions of bacterial biomass showed fewer similarities to these two parameters. This could be explained by variations of litter exploitation through the biomass. Microbial activity started immediately after the thaw while root growth had a longer time lag. An influence of root development on soil microbes was proposed for sites where microorganisms and roots had a tight relationship caused by a more intensive root structure. Also a reduction of microbial activity due to soil compaction in the samples from a wheel track could not be observed under laboratory conditions. New methodological approaches of differential staining for live and dead organisms were applied in order to follow changes within the microbial community. Under laboratory conditions freeze and thaw cycles showed a damaging influence on parts of the soil bacteria. Additionally, different patterns for active vs.non-active bacteria were noticeable after freeze-thaw cycles.

  13. Mercury speciation and effects on soil microbial activities.

    Science.gov (United States)

    Tazisong, Irenus A; Senwo, Zachary N; Williams, Miranda I

    2012-01-01

    To study Hg toxicity on soil microbes and their activities, it is necessary to understand its various forms in soils. The objectives of this study were to investigate Hg speciation in four soil types spiked with Hg (300 mg kg(-1) soil) and its effects on soil microbial respiration and enzymes (amidohydrolases and phosphatase) activities. An assessment of the chemical forms, amounts, reactions, and mobility of Hg in soils and sediments is of significant importance to improve and maintain soil and environmental health and sustainability. Mercury speciation analysis was investigated under acidic and alkaline conditions using a modified sequential procedure, which differentiates Hg into the four distinct fractions. Soil microbial respiration and enzymes activities were determined under laboratory settings, by incubating the soils at 25°C for 30 days, and then determining the amount of CO(2) evolved. Speciation results revealed that the water soluble form was the least, with soil types investigated irrespective of the pH condition, while the residual fraction was the most abundant (> 80%) in Canisteo, Houston, and Ketona soils under acidic conditions and soil. Under alkaline conditions, the residual fraction was ≤ 70% in Canisteo, Houston, and ketona and ≤ 29% in Decatur soil. The exchangeable fraction was the second most abundant fraction in the soils used ranging from 3.7-50.0% under acid conditions and 16.9-52.1% under alkaline conditions indicating that Hg desorption was found to be more favorable under alkaline than acidic conditions. Soil respiration was suppressed by Hg especially at the 100 mg kg(-1) concentration level. Amidohydrolases and phosphatases' response in the presence of Hg was variable. Amidohydrolases were more sensitive to Hg (18-90%) than phosphatase (0-35%) in all soils. This study demonstrated that the forms in which Hg exist in soils may determine its bioavailability and toxicity. Also microbial respiration and enzyme activities are

  14. Carbon use efficiency (CUE) and biomass turnover of soil microbial communities as affected by bedrock, land management and soil temperature and moisture

    Science.gov (United States)

    Zheng, Qing; Hu, Yuntao; Richter, Andreas; Wanek, Wolfgang

    2017-04-01

    Soil microbial carbon use efficiency (CUE), defined as the proportion of organic C taken up that is allocated to microbial growth, represents an important synthetic representation of microbial community C metabolism that describes the flux partitioning between microbial respiration and growth. Therefore, studying microbial CUE is critical for the understanding of soil C cycling. Microbial CUE is thought to vary with environmental conditions (e.g. temperature and soil moisture). Microbial CUE is thought to decrease with increasing temperature and declining soil moisture, as the latter may trigger stress responses (e.g. the synthesis of stress metabolites), which may consequently lower microbial community CUE. However, these effects on microbial CUE have not been adequately measured so far due to methodological restrictions. The most widely used methods for microbial CUE estimation are based on tracing 13C-labeled substrates into microbial biomass and respiratory CO2, approaches that are known to overestimate microbial CUE of native organic matter in soil. Recently, a novel substrate-independent approach based on the measurement of (i) respiration rates and (ii) the incorporation rates of 18O from labelled water into newly formed microbial DNA has been developed in our laboratory for measuring microbial CUE. This approach overcomes the shortcomings of previously used methods and has already been shown to yield realistic estimations of soil microbial CUE. This approach can also be applied to concurrently measure microbial biomass turnover rates, which also influence the sequestration of soil organic C. Microbial turnover rates are also thought to be impacted by environmental factors, but rarely have been directly measured so far. Here, we aimed at determining the short-term effects of environmental factors (soil temperature and soil moisture) on microbial CUE and microbial biomass turnover rates based on the novel 18O approach. Soils from three land-use types (arable

  15. Soil Respiration and Student Inquiry: A Perfect Match

    Science.gov (United States)

    Hoyt, Catherine Marie; Wallenstein, Matthew David

    2011-01-01

    This activity explores the cycling of carbon between the atmosphere (primarily as CO[subscript 2]) and biomass in plants, animals, and microscopic organisms. Students design soil respiration experiments using a protocol that resembles current practice in soil ecology. Three methods for measuring soil respiration are presented. Student-derived…

  16. Interpreting diel hysteresis between soil respiration and temperature

    Science.gov (United States)

    C. Phillips; N. Nickerson; D. Risk; B.J. Bond

    2011-01-01

    Increasing use of automated soil respiration chambers in recent years has demonstrated complex diel relationships between soil respiration and temperature that are not apparent from less frequent measurements. Soil surface flux is often lagged from soil temperature by several hours, which results in semielliptical hysteresis loops when surface flux is plotted as a...

  17. Differential soil respiration responses to changing hydrologic regimes

    Science.gov (United States)

    Vincent J. Pacific; Brian L. McGlynn; Diego A. Riveros-Iregui; Howard E. Epstein; Daniel L. Welsch

    2009-01-01

    Soil respiration is tightly coupled to the hydrologic cycle (i.e., snowmelt and precipitation timing and magnitude). We examined riparian and hillslope soil respiration across a wet (2005) and a dry (2006) growing season in a subalpine catchment. When comparing the riparian zones, cumulative CO2 efflux was 33% higher, and peak efflux occurred 17 days earlier during the...

  18. Soil Respiration and Student Inquiry: A Perfect Match

    Science.gov (United States)

    Hoyt, Catherine Marie; Wallenstein, Matthew David

    2011-01-01

    This activity explores the cycling of carbon between the atmosphere (primarily as CO[subscript 2]) and biomass in plants, animals, and microscopic organisms. Students design soil respiration experiments using a protocol that resembles current practice in soil ecology. Three methods for measuring soil respiration are presented. Student-derived…

  19. Antibiotic efficacy is linked to bacterial cellular respiration.

    Science.gov (United States)

    Lobritz, Michael A; Belenky, Peter; Porter, Caroline B M; Gutierrez, Arnaud; Yang, Jason H; Schwarz, Eric G; Dwyer, Daniel J; Khalil, Ahmad S; Collins, James J

    2015-07-07

    Bacteriostatic and bactericidal antibiotic treatments result in two fundamentally different phenotypic outcomes--the inhibition of bacterial growth or, alternatively, cell death. Most antibiotics inhibit processes that are major consumers of cellular energy output, suggesting that antibiotic treatment may have important downstream consequences on bacterial metabolism. We hypothesized that the specific metabolic effects of bacteriostatic and bactericidal antibiotics contribute to their overall efficacy. We leveraged the opposing phenotypes of bacteriostatic and bactericidal drugs in combination to investigate their activity. Growth inhibition from bacteriostatic antibiotics was associated with suppressed cellular respiration whereas cell death from most bactericidal antibiotics was associated with accelerated respiration. In combination, suppression of cellular respiration by the bacteriostatic antibiotic was the dominant effect, blocking bactericidal killing. Global metabolic profiling of bacteriostatic antibiotic treatment revealed that accumulation of metabolites involved in specific drug target activity was linked to the buildup of energy metabolites that feed the electron transport chain. Inhibition of cellular respiration by knockout of the cytochrome oxidases was sufficient to attenuate bactericidal lethality whereas acceleration of basal respiration by genetically uncoupling ATP synthesis from electron transport resulted in potentiation of the killing effect of bactericidal antibiotics. This work identifies a link between antibiotic-induced cellular respiration and bactericidal lethality and demonstrates that bactericidal activity can be arrested by attenuated respiration and potentiated by accelerated respiration. Our data collectively show that antibiotics perturb the metabolic state of bacteria and that the metabolic state of bacteria impacts antibiotic efficacy.

  20. Molecular AND logic gate based on bacterial anaerobic respiration.

    Science.gov (United States)

    Arugula, Mary Anitha; Shroff, Namita; Katz, Evgeny; He, Zhen

    2012-10-21

    Enzyme coding genes that integrate information for anaerobic respiration in Shewanella oneidensis MR-1 were used as input for constructing an AND logic gate. The absence of one or both genes inhibited electrochemically-controlled anaerobic respiration, while wild type bacteria were capable of accepting electrons from an electrode for DMSO reduction.

  1. Simulation of Human Respiration with Breathing Thermal Manikin

    DEFF Research Database (Denmark)

    Bjørn, Erik

    The human respiration contains carbon dioxide, bioeffluents, and perhaps virus or bacteria. People may also indulge in activities that produce contaminants, as for example tobacco smoking. For these reasons, the human respiration remains one of the main contributors to contamination of the indoor...

  2. Microbial Activity and Silica Degradation in Rice Straw

    Science.gov (United States)

    Kim, Esther Jin-kyung

    Abundantly available agricultural residues like rice straw have the potential to be feedstocks for bioethanol production. Developing optimized conditions for rice straw deconstruction is a key step toward utilizing the biomass to its full potential. One challenge associated with conversion of rice straw to bioenergy is its high silica content as high silica erodes machinery. Another obstacle is the availability of enzymes that hydrolyze polymers in rice straw under industrially relevant conditions. Microbial communities that colonize compost may be a source of enzymes for bioconversion of lignocellulose to products because composting systems operate under thermophilic and high solids conditions that have been shown to be commercially relevant. Compost microbial communities enriched on rice straw could provide insight into a more targeted source of enzymes for the breakdown of rice straw polysaccharides and silica. Because rice straw is low in nitrogen it is important to understand the impact of nitrogen concentrations on the production of enzyme activity by the microbial community. This study aims to address this issue by developing a method to measure microbial silica-degrading activity and measure the effect of nitrogen amendment to rice straw on microbial activity and extracted enzyme activity during a high-solids, thermophilic incubation. An assay was developed to measure silica-degrading enzyme or silicase activity. This process included identifying methods of enzyme extraction from rice straw, identifying a model substrate for the assay, and optimizing measurement techniques. Rice straw incubations were conducted with five different levels of nitrogen added to the biomass. Microbial activity was measured by respiration and enzyme activity. A microbial community analysis was performed to understand the shift in community structure with different treatments. With increased levels of nitrogen, respiration and cellulose and hemicellulose degrading activity

  3. Redefinition and global estimation of basal ecosystem respiration rate

    DEFF Research Database (Denmark)

    Yuan, Wenping; Luo, Yiqi; Li, Xianglan;

    2011-01-01

    Basal ecosystem respiration rate (BR), the ecosystem respiration rate at a given temperature, is a common and important parameter in empirical models for quantifying ecosystem respiration (ER) globally. Numerous studies have indicated that BR varies in space. However, many empirical ER models still...... use a global constant BR largely due to the lack of a functional description for BR. In this study, we redefined BR to be ecosystem respiration rate at the mean annual temperature. To test the validity of this concept, we conducted a synthesis analysis using 276 site-years of eddy covariance data...... use efficiency GPP model (i.e., EC-LUE) was applied to estimate global GPP, BR and ER with input data from MERRA (Modern Era Retrospective-Analysis for Research and Applications) and MODIS (Moderate resolution Imaging Spectroradiometer). The global ER was 103 Pg C yr −1, with the highest respiration...

  4. Light-enhanced oxygen respiration in benthic phototrophic communities

    DEFF Research Database (Denmark)

    Epping, EHG; Jørgensen, BB

    1996-01-01

    Two microelectrode studies demonstrate the effect of Light intensity and photosynthesis on areal oxygen respiration in a hypersaline mat at Guerrero Negro, Mexico, and in an intertidal sediment at Texel, The Netherlands. The hypersaline mat was studied in the laboratory at light intensities of 0...... light intensities. Areal respiration, calculated from the difference between areal gross and areal net photosynthesis, increased from 3.9 to 14.4 nmol O-2 cm(2) min(-1) with increasing surface irradiance. This light-enhanced areal respiration was related to an increase in oxygen penetration depth from 0.......2 to 2.0 mm, thus expanding the volume of sediment involved in oxygen respiration beneath the mat surface. The mean rate of oxygen respiration per volume of mat remained constant at a rate of similar to 100 nmol O-2 cm(-3) min(-1). Oxygen profiles for the intertidal sediment were recorded in situ during...

  5. Respirable dust measured downwind during rock dust application.

    Science.gov (United States)

    Harris, M L; Organiscak, J; Klima, S; Perera, I E

    2017-05-01

    The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) conducted underground evaluations in an attempt to quantify respirable rock dust generation when using untreated rock dust and rock dust treated with an anticaking additive. Using personal dust monitors, these evaluations measured respirable rock dust levels arising from a flinger-type application of rock dust on rib and roof surfaces. Rock dust with a majority of the respirable component removed was also applied in NIOSH's Bruceton Experimental Mine using a bantam duster. The respirable dust measurements obtained downwind from both of these tests are presented and discussed. This testing did not measure miners' exposure to respirable coal mine dust under acceptable mining practices, but indicates the need for effective continuous administrative controls to be exercised when rock dusting to minimize the measured amount of rock dust in the sampling device.

  6. CO(2) Inhibits Respiration in Leaves of Rumex crispus L.

    Science.gov (United States)

    Amthor, J S; Koch, G W; Bloom, A J

    1992-02-01

    Curly dock (Rumex crispus L.) was grown from seed in a glasshouse at an ambient CO(2) partial pressure of about 35 pascals. Apparent respiration rate (CO(2) efflux in the dark) of expanded leaves was then measured at ambient CO(2) partial pressure of 5 to 95 pascals. Calculated intercellular CO(2) partial pressure was proportional to ambient CO(2) partial pressure in these short-term experiments. The CO(2) level strongly affected apparent respiration rate: a doubling of the partial pressure of CO(2) typically inhibited respiration by 25 to 30%, whereas a decrease in CO(2) elicited a corresponding increase in respiration. These responses were readily reversible. A flexible, sensitive regulatory interaction between CO(2) (a byproduct of respiration) and some component(s) of heterotrophic metabolism is indicated.

  7. Representing Microbial Dormancy in Soil Decomposition Models Improves Model Performance and Reveals Key Ecosystem Controls on Microbial Activity

    Science.gov (United States)

    He, Y.; Yang, J.; Zhuang, Q.; Wang, G.; Liu, Y.

    2014-12-01

    Climate feedbacks from soils can result from environmental change and subsequent responses of plant and microbial communities and nutrient cycling. Explicit consideration of microbial life history traits and strategy may be necessary to predict climate feedbacks due to microbial physiology and community changes and their associated effect on carbon cycling. In this study, we developed an explicit microbial-enzyme decomposition model and examined model performance with and without representation of dormancy at six temperate forest sites with observed soil efflux ranged from 4 to 10 years across different forest types. We then extrapolated the model to all temperate forests in the Northern Hemisphere (25-50°N) to investigate spatial controls on microbial and soil C dynamics. Both models captured the observed soil heterotrophic respiration (RH), yet no-dormancy model consistently exhibited large seasonal amplitude and overestimation in microbial biomass. Spatially, the total RH from temperate forests based on dormancy model amounts to 6.88PgC/yr, and 7.99PgC/yr based on no-dormancy model. However, no-dormancy model notably overestimated the ratio of microbial biomass to SOC. Spatial correlation analysis revealed key controls of soil C:N ratio on the active proportion of microbial biomass, whereas local dormancy is primarily controlled by soil moisture and temperature, indicating scale-dependent environmental and biotic controls on microbial and SOC dynamics. These developments should provide essential support to modeling future soil carbon dynamics and enhance the avenue for collaboration between empirical soil experiment and modeling in the sense that more microbial physiological measurements are needed to better constrain and evaluate the models.

  8. Soil respiration and carbon responses to logging debris and competing vegetation

    Science.gov (United States)

    Robert A. Slesak; Stephen H. Schoenholtz; Timothy B. Harrington

    2010-01-01

    Management practices following forest harvesting that modify organic matter (OM) inputs and influence changes in the soil environment have the potential to alter soil C pools, but there is still much uncertainty regarding how these practices influence soil C flux. We examined the influence of varying amounts of logging-debris retention (0, 40, and 80% coverage) and...

  9. Effect of pyrene and cadmium on microbial activity and community structure in soil.

    Science.gov (United States)

    Lu, Mang; Xu, Kui; Chen, Jun

    2013-04-01

    In this study, a greenhouse experiment was conducted to investigate interactive effects of cadmium (Cd) × pyrene × plant treatments on soil microbial activity and community structure. The results demonstrated that the basal respiration, microbial biomass carbon and metabolic quotient in both unplanted and rhizosphere soil were significantly influenced by interaction of Cd and pyrene. The combined application of Cd and pyrene caused a significantly greater biocidal influence on the soil microorganisms than the single spiking of Cd or pyrene. The soil basal respiration increased with the spiking of 2.5 mg kg(-1) Cd in both unplanted and rhizosphere soil. The eco-physiological index of Cd-tolerant populations was significantly different among the unplanted soil, rhizoplane and rhizosphere soil of tall fescue, indicating a slightly uneven distribution of fast- and slow-growing tolerant bacteria. Obvious differences in microbial activity were observed among treatments due to different physicochemical characteristics of the rhizosphere soils depending on the plant species.

  10. 76 FR 3175 - Proposed Extension of Existing Information Collection; Respirator Program Records

    Science.gov (United States)

    2011-01-19

    ... Safety and Health Administration Proposed Extension of Existing Information Collection; Respirator... miners against hazards. Where protective equipment or respirators are required because of exposure to... respirators is essential for ensuring that workers are properly and effectively using the equipment. Title...

  11. [Effects of simulated nitrogen deposition on the fine root characteristics and soil respiration in a Pleioblastus amarus plantation in rainy area of West China].

    Science.gov (United States)

    Tu, Li-hua; Hu, Ting-xing; Zhang, Jian; He, Yuan-yang; Tian, Xiang-yu; Xiao, Yin-long

    2010-10-01

    Fine root is critical in the belowground carbon (C) cycling in forest ecosystem. Aimed to understand the effects of nitrogen (N) deposition on the fine root characteristics and soil respiration in Pleioblastus amarus plantation, a two-year field experiment was conducted in the Rainy Area of West China. Four treatments with different levels of N deposition were installed, i. e., CK (0 g N x m(-2) x a(-1)), low N (5 g N x m(-2) x a(-1)), medium N (15 g N x m(-2) x a(-1)), and high N (30 g N x m(-2) x a(-1)). There were great differences in the biomass and element contents of Nitrogen deposition increased the biomass of deposition. The annual soil respiration rate in treatments CK, low N, medium N, and high N was (5.85 +/- 0.43), (6.48 +/- 0.71), (6.84 +/- 0.57), and (7.62 +/- 0.55) t C x hm(-2) x a(-1), respectively, indicating that N deposition had obvious promotion effects on soil respiration. There were significant linear relationships between the annual soil respiration rate and the biomass and N content of deposition increased the fine root biomass and promoted the root metabolism, and stimulated the rhizospheric soil respiration rate via promoting microbial activities.

  12. Effects of Simulated Nitrogen Deposition on Soil Respiration in a Populus euphratica Community in the Ebinur Lake Area, a Desert Ecosystem of Northwestern China.

    Science.gov (United States)

    He, Xuemin; Lv, Guanghui; Qin, Lu; Chang, Shunli; Yang, Min; Yang, Jianjun; Yang, Xiaodong

    2015-01-01

    One of the primary limiting factors for biological activities in desert ecosystems is nitrogen (N). This study therefore examined the effects of N and investigated the responses of an arid ecosystem to global change. We selected the typical desert plant Populus euphratica in a desert ecosystem in the Ebinur Lake area to evaluate the effects of N deposition on desert soil respiration. Three levels of N deposition (0, 37.5 and 112.5 kg·N·ha-1·yr-1) were randomly artificially provided to simulate natural N deposition. Changes in the soil respiration rates were measured from July to September in both 2010 and 2013, after N deposition in April 2010. The different levels of N deposition affected the total soil N, soil organic matter, soil C/N ratio, microorganism number, and microbial community structure and function. However, variable effects were observed over time in relation to changes in the magnitude of N deposition. Simulated high N deposition significantly reduced the soil respiration rate by approximately 23.6±2.5% (Psoil respiration rate by approximately 66.7±2.7% (Psoil moisture, whereas N deposition significantly increased the soil temperature in the 0-5 cm layer (Psoil respiration rate by altering soil properties.

  13. Competencies and Their Assessment

    Science.gov (United States)

    Drisko, James W.

    2014-01-01

    This article explores competencies and methods for their assessment in higher education and in social work's accreditation standards. Many contemporary policy and educational accreditation efforts employ the model of competency assessment. The current emphasis on accountability in higher education, including the Council on Social Work…

  14. Analyzing ADN competencies.

    Science.gov (United States)

    Mitchell, P R

    1989-01-01

    El Paso Community College District, using the DACUM Process, identified 19 major competency areas with 313 specific competencies for AD Nursing. This article provides an overview of the DACUM Process, a discussion of the application to the ADN program, a summary of the results, and future activities.

  15. Cultural Competence Revisited

    Science.gov (United States)

    Garran, Ann Marie; Werkmeister Rozas, Lisa

    2013-01-01

    In 2001, the National Association of Social Workers (NASW) adopted 10 discrete standards of culturally competent practice which undergird our commitment to diversity and social justice. The concept of intersectionality is newly emerging in social work, though, causing us to reflect on our current conceptualizations of cultural competence.…

  16. Intercultural Competence Teaching

    Institute of Scientific and Technical Information of China (English)

    HUI Ran

    2015-01-01

    It is widely realized that cultural competence is playing an increasingly important role in language teaching because of the close associations between culture and language. To enhance the efficiency of language teaching, this essay will elucidate the importance of intercultural competence teaching and introduce three methods of cultural teaching.

  17. Competence, Curriculum, and Control.

    Science.gov (United States)

    Jackson, Nancy S.

    1988-01-01

    Draws upon a case study of a community college program review to examine the application of a competency-based approach to the process of curriculum design. Suggests that competency-based curriculum development shifts the basis for decision making from teacher knowledge to an objectified accounting system of employers and curriculum technicians.…

  18. Validating clinical competence.

    Science.gov (United States)

    Chappell, Kathy; Koithan, Mary

    2012-07-01

    Professional registered nurses must be competent to provide care in today's fast-paced, highly technical clinical environment. Competency programs designed to teach and evaluate essential knowledge, skills, and abilities of registered nurses are one method organizations may use to demonstrate nursing proficiency.

  19. Competencies in Ornamental Horticulture

    Science.gov (United States)

    Loewen, Curtis E.

    1974-01-01

    Based on the author's dissertation, this article pertains to the identification of competencies for ornamental horticulture workers in Oregon. Findings were based on interviews with 56 ornamental horticulture business employers regarding 100 competencies. The method used can serve as a model for obtaining occupational information to develop and…

  20. Developing Clinical Competence

    NARCIS (Netherlands)

    P.F. Wimmers (Paul)

    2006-01-01

    textabstractThe development of clinical competence is the main purpose of medical education. The long road to become clinically competent starts on the first day of medical school, and every institution strives to select the best students. The responsibility of medical schools is to train th

  1. The Spiritual Competency Scale

    Science.gov (United States)

    Robertson, Linda A.

    2010-01-01

    This study describes the development of the Spiritual Competency Scale, which was based on the Association for Spiritual, Ethical and Religious Values in Counseling's original Spiritual Competencies. Participants were 662 counseling students from religiously based and secular universities nationwide. Exploratory factor analysis revealed a 22-item,…

  2. Assessment of Innovation Competency

    DEFF Research Database (Denmark)

    Nielsen, Jan Alexis

    2015-01-01

    The author employed a 3-step qualitative research design with multiple instances of source validation to capture expert teachers’ (n = 28) reflections on which manifest signs they would look for when they asses students’ innovation competency. The author reports on the thematic analysis of the re......The author employed a 3-step qualitative research design with multiple instances of source validation to capture expert teachers’ (n = 28) reflections on which manifest signs they would look for when they asses students’ innovation competency. The author reports on the thematic analysis...... of the recorded talk in interaction that occurred in teacher group discussion sessions at 5 upper secondary schools. Based on the analysis, it was possible to extrapolate assessment criteria for 5 subcompetencies relevant to innovation (creative competency, collaboration competency, navigation competency, action...... competency, and communication competency) as well as assessment criteria for a number of skills relevant to these subcompetencies. These assessment criteria, it is argued, largely resonate with existing literature and they provide a detailed glimpse into how assessment of innovation competency could...

  3. Developing Clinical Competence

    NARCIS (Netherlands)

    P.F. Wimmers (Paul)

    2006-01-01

    textabstractThe development of clinical competence is the main purpose of medical education. The long road to become clinically competent starts on the first day of medical school, and every institution strives to select the best students. The responsibility of medical schools is to train

  4. Microbial Activity Indices: Sensitive Soil Quality Indicators for Trace Metal Stress

    Institute of Scientific and Technical Information of China (English)

    LI Yong-Tao; T.BECQUER; C.QUANTIN; M.BENEDETTI; P.LAVELLE; DAI Jun

    2005-01-01

    Physicochemical properties, total and DTPA (diethylenetriaminepentaacetic acid)-extractable Cu, Zn, Pb and Cd contents, microbial biomass carbon (C) content and the organic C mineralization rate of the soils in a long-term trace metal-contaminated paddy region of Guangdong, China were determined to assess the sensitivity of microbial indices to moderately metal-contaminated paddy soils. The mean contents of total Cu, Zn, Pb and Cd were 251,250, 171, and 2.4mg kg-1 respectively. DTPA-extractable metals were correlated positively and significantly with total metals, CEC, and organic C (except for DTPA-extractable Cd), while they were negatively and highly significantly correlated with pH, total Fe and Mn. Metal stress resulted in relatively low ratios of microbial biomass C to organic C and in remarkable inhibition of the microbial metabolic quotient and C mineralization rate, which eventually led to increases in soil organic C and C/N. Moreover, microbial respiratory activity showed a stronger correlation to DTPA-extractable metals than to total metal content. Likewise, in the acid paddy soils some "linked" microbial activity indices, such as metabolic quotient and ratios of basal respiration to organic C, especially during initial incubation, were found to be more sensitive indicators of soil trace metal contamination than microbial biomass C or basal respiration alone.

  5. Differences in Soil Microbial Biomass and Activity for Six Agroecosystems with a Management Disturbance Gradient

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-Jian; FENG Jin-Xia; J. WU; K. PARKER

    2004-01-01

    Different management practices in six agroecosystems located near Goldsboro, NC, USA were conducted including a successional field (SU), a plantation woodlot (WO), an integrated cropping system with animals (IN), an organic farming system (OR), and two cash-grain cropping systems employing either tillage (CT) or no-tillage (NT) to examine if and how microbial biomass and activity differ in response to alterations in disturbance intensity from six land management strategies. Results showed that soil microbial biomass and activity differed, with microbial activity in intermediately disturbed ecosystems (NT, OR, IN) being significantly higher (P < 0.01) than systems with either high or low disturbance intensities. There was also a significant and a highly significant ecosystem effect from the treatments on microbial biomass C (MBC) (P < 0.05) and on microbial activity (respiration) (P < 0.01), respectively. Multiple comparisons of mean respiration rates distinctly separated the six ecosystem types into three groups: CT < NT, SU and WO < OR and IN.Thus, for detecting microbial response to disturbance changes these results indicated that the active component of the soil microbial community was a better indicator than total biomass.

  6. Effect of biosolid waste compost on soil respiration in salt-affected soils

    Science.gov (United States)

    Raya, Silvia; Gómez, Ignacio; García, Fuensanta; Navarro, José; Jordán, Manuel Miguel; Belén Almendro, María; Martín Soriano, José

    2013-04-01

    A great part of mediterranean soils are affected by salinization. This is an important problem in semiarid areas increased by the use of low quality waters, the induced salinization due to high phreatic levels and adverse climatology. Salinization affects 25% of irrigated agriculture, producing important losses on the crops. In this situation, the application of organic matter to the soil is one of the possible solutions to improve their quality. The main objective of this research was to asses the relation between the salinity level (electrical conductivity, EC) in the soil and the response of microbial activity (soil respiration rate) after compost addition. The study was conducted for a year. Soil samples were collected near to an agricultural area in Crevillente and Elche, "El Hondo" Natural Park (Comunidad de Regantes from San Felipe Neri). The experiment was developed to determine and quantify the soil respiration rate in 8 different soils differing in salinity. The assay was done in close pots -in greenhouse conditions- containing soil mixed with different doses of sewage sludge compost (2, 4 and 6%) besides the control. They were maintained at 60% of water holding capacity (WHC). Soil samples were analyzed every four months for a year. The equipment used to estimate the soil respiration was a Bac-Trac and CO2 emitted by the soil biota was measured and quantified by electrical impedance changes. It was observed that the respiration rate increases as the proportion of compost added to each sample increases as well. The EC was incremented in each sampling period from the beginning of the experiment, probably due to the fact that soils were in pots and lixiviation was prevented, so the salts couldńt be lost from soil. Over time the compost has been degraded and, it was more susceptible to be mineralized. Salts were accumulated in the soil. Also it was observed a decrease of microbial activity with the increase of salinity in the soil. Keywords: soil

  7. Impact of Metal Pollution and Thlaspi caerulescens Growth on Soil Microbial Communities▿

    Science.gov (United States)

    Epelde, Lur; Becerril, José M.; Kowalchuk, George A.; Deng, Ye; Zhou, Jizhong; Garbisu, Carlos

    2010-01-01

    Soil microorganisms drive critical functions in plant-soil systems. As such, various microbial properties have been proposed as indicators of soil functioning, making them potentially useful in evaluating the recovery of polluted soils via phytoremediation strategies. To evaluate microbial responses to metal phytoextraction using hyperaccumulators, a microcosm experiment was carried out to study the impacts of Zn and/or Cd pollution and Thlaspi caerulescens growth on key soil microbial properties: basal respiration; substrate-induced respiration (SIR); bacterial community structure as assessed by PCR-denaturing gradient gel electrophoresis (DGGE); community sizes of total bacteria, ammonia-oxidizing bacteria, and chitin-degrading bacteria as assessed by quantitative PCR (Q-PCR); and functional gene distributions as determined by functional gene arrays (GeoChip). T. caerulescens proved to be suitable for Zn and Cd phytoextraction: shoots accumulated up to 8,211 and 1,763 mg kg−1 (dry weight [DW]) of Zn and Cd, respectively. In general, Zn pollution led to decreased levels of basal respiration and ammonia-oxidizing bacteria, while T. caerulescens growth increased the values of substrate-induced respiration (SIR) and total bacteria. In soils polluted with 1,000 mg Zn kg−1 and 250 mg Cd kg−1 (DW), soil bacterial community profiles and the distribution of microbial functional genes were most affected by the presence of metals. Metal-polluted and planted soils had the highest percentage of unique genes detected via the GeoChip (35%). It was possible to track microbial responses to planting with T. caerulescens and to gain insight into the effects of metal pollution on soilborne microbial communities. PMID:20935131

  8. Linking temperature sensitivity of soil organic matter decomposition to its molecular structure, accessibility, and microbial physiology.

    Science.gov (United States)

    Wagai, Rota; Kishimoto-Mo, Ayaka W; Yonemura, Seiichiro; Shirato, Yasuhito; Hiradate, Syuntaro; Yagasaki, Yasumi

    2013-04-01

    Temperature sensitivity of soil organic matter (SOM) decomposition may have a significant impact on global warming. Enzyme-kinetic hypothesis suggests that decomposition of low-quality substrate (recalcitrant molecular structure) requires higher activation energy and thus has greater temperature sensitivity than that of high-quality, labile substrate. Supporting evidence, however, relies largely on indirect indices of substrate quality. Furthermore, the enzyme-substrate reactions that drive decomposition may be regulated by microbial physiology and/or constrained by protective effects of soil mineral matrix. We thus tested the kinetic hypothesis by directly assessing the carbon molecular structure of low-density fraction (LF) which represents readily accessible, mineral-free SOM pool. Using five mineral soil samples of contrasting SOM concentrations, we conducted 30-days incubations (15, 25, and 35 °C) to measure microbial respiration and quantified easily soluble C as well as microbial biomass C pools before and after the incubations. Carbon structure of LFs (soil was measured by solid-state (13) C-NMR. Decomposition Q10 was significantly correlated with the abundance of aromatic plus alkyl-C relative to O-alkyl-C groups in LFs but not in bulk soil fraction or with the indirect C quality indices based on microbial respiration or biomass. The warming did not significantly change the concentration of biomass C or the three types of soluble C despite two- to three-fold increase in respiration. Thus, enhanced microbial maintenance respiration (reduced C-use efficiency) especially in the soils rich in recalcitrant LF might lead to the apparent equilibrium between SOM solubilization and microbial C uptake. Our results showed physical fractionation coupled with direct assessment of molecular structure as an effective approach and supported the enzyme-kinetic interpretation of widely observed C quality-temperature relationship for short-term decomposition. Factors

  9. Cellular respiration: replicating in vivo systems biology for in ...

    Science.gov (United States)

    This editorial develops a philosophy for expanding the scope of Journal of Breath Research (JBR) into the realm of cellular level study, and links certain topics back to more traditional systemic research for understanding human health based on exhaled breath constituents. The express purpose is to provide a publication outlet for novel breath related research that includes in vitro studies, especially those that explore the biological origin and expression of compounds that may ultimately influence the constituents of exhaled breath. The new topics include all manner of methods and instrumentations for making in vivo and in vitro measurements, the use of different biological media (blood, urine saliva, swabs) including human and microbial cell-lines, in vitro kinetic studies of metabolism, and advances in ex vivo methods for maintaining metabolic competency and viability of biological samples. Traditionally, JBR has published articles on human breath analysis for diagnosing disease, tracking health state, assessing the dose and effect of exogenous chemicals, and contributions of malodorous compounds from the oral/nasal cavity. These have also included research describing novel sampling and analytical technologies, most notably those implementing mass spectrometry, chemical sensors and optical measurement instrumentation (Amann and Smith 2013). The journal’s original scope has also embraced animal models as surrogates for human sampling, new mathematical and

  10. Nonlinear response of soil respiration to increasing nitrogen additions in a Tibetan alpine steppe

    Science.gov (United States)

    Peng, Yunfeng; Li, Fei; Zhou, Guoying; Fang, Kai; Zhang, Dianye; Li, Changbin; Yang, Guibiao; Wang, Guanqin; Wang, Jun; Mohammat, Anwar; Yang, Yuanhe

    2017-02-01

    Nitrogen (N) availability is a key regulator of carbon (C) cycling in terrestrial ecosystems. Anthropogenic N input, such as N deposition and fertilization, increases N availability in soil, which has important implications for an ecosystem’s C storage and loss. Soil respiration (Rs), which is the second largest C flux from terrestrial ecosystems to the atmosphere, plays an important role in terrestrial C cycles. The direction and magnitude of the responses of Rs and its components to N addition have been widely evaluated, but it remains unclear how these processes change across multiple N addition levels. Here we conducted a two-year field experiment to examine the changes of Rs and its autotrophic respiration (Ra) and heterotrophic respiration (Rh) components along a gradient of eight N levels (0, 1 2, 4, 8, 16, 24, 32 g m‑2 yr‑1) in a Tibetan alpine steppe, and used structural equation modeling (SEM) to explore the relative contributions of biotic and abiotic variables and their direct and indirect pathways regulating the Ra and Rh. Our results indicated that both Rs and Ra exhibited first increasing and then subsequent decreasing trends at the threshold of 8 g N m‑2 yr‑1. In contrast, the Rh declined linearly with the N addition rate continuously increasing. SEM analysis revealed that, among various environmental factors, soil temperature was the most important one modulating Rs, which not only had a direct effect on the two Rs components, but also indirectly regulated the Ra and Rh via root and microbial biomass. These findings suggest that the nonlinear response patterns of Rs should be considered for better predicting terrestrial C balance, given that anthropogenic N input to the terrestrial ecosystems is increasing continuously.

  11. Biochar has no effect on soil respiration across Chinese agricultural soils.

    Science.gov (United States)

    Liu, Xiaoyu; Zheng, Jufeng; Zhang, Dengxiao; Cheng, Kun; Zhou, Huimin; Zhang, Afeng; Li, Lianqing; Joseph, Stephen; Smith, Pete; Crowley, David; Kuzyakov, Yakov; Pan, Genxing

    2016-06-01

    Biochar addition to soil has been widely accepted as an option to enhance soil carbon sequestration by introducing recalcitrant organic matter. However, it remains unclear whether biochar will negate the net carbon accumulation by increasing carbon loss through CO2 efflux from soil (soil respiration). The objectives of this study were to address: 1) whether biochar addition increases soil respiration; and whether biochar application rate and biochar type (feedstock and pyrolyzing system) affect soil respiration. Two series of field experiments were carried out at 8 sites representing the main crop production areas in China. In experiment 1, a single type of wheat straw biochar was amended at rates of 0, 20 and 40 tha(-1) in four rice paddies and three dry croplands. In experiment 2, four types of biochar (varying in feedstock and pyrolyzing system) were amended at rates of 0 and 20 tha(-1) in a rice paddy under rice-wheat rotation. Results showed that biochar addition had no effect on CO2 efflux from soils consistently across sites, although it increased topsoil organic carbon stock by 38% on average. Meanwhile, CO2 efflux from soils amended with 40 t of biochar did not significantly higher than soils amended with 20 t of biochar. While the biochars used in Experiment 2 had different carbon pools and physico-chemical properties, they had no effect on soil CO2 efflux. The soil CO2 efflux following biochar addition could be hardly explained by the changes in soil physic-chemical properties and in soil microbial biomass. Thus, we argue that biochar will not negate the net carbon accumulation by increasing carbon loss through CO2 efflux in agricultural soils.

  12. Microbial conversions of terpenoids

    OpenAIRE

    Parshikov, Igor A

    2015-01-01

    The monograph describes examples of the application of microbial technology for obtaining of derivatives of terpenoids. Obtaining new derivatives of terpenoids, including artemisinin derivatives with increased antimalarial activity, is an important goal of research in microbial biotechnology and medicinal chemistry.

  13. Merging metabolism and power: development of a novel photobioelectric device driven by photosynthesis and respiration.

    Directory of Open Access Journals (Sweden)

    Ryan J Powell

    Full Text Available Generation of renewable energy is one of the grand challenges facing our society. We present a new bio-electric technology driven by chemical gradients generated by photosynthesis and respiration. The system does not require pure cultures nor particular species as it works with the core metabolic principles that define phototrophs and heterotrophs. The biology is interfaced with electrochemistry with an alkaline aluminum oxide cell design. In field trials we show the system is robust and can work with an undefined natural microbial community. Power generated is light and photosynthesis dependent. It achieved a peak power output of 33 watts/m(2 electrode. The design is simple, low cost and works with the biological processes driving the system by removing waste products that can impede growth. This system is a new class of bio-electric device and may have practical implications for algal biofuel production and powering remote sensing devices.

  14. Relationship Between Vegetation Restoration and Soil Microbial Characteristics in Degraded Karst Regions: A Case StudyABSTRACT

    Institute of Scientific and Technical Information of China (English)

    WEI Yuan; YU Li-Fei; MANG Jin-Chi; YU Yuan-Chun; D.L.DEANGELIS

    2011-01-01

    The mechanism of vegetation restoration on degraded karst regions has been a research focus of soil science and ecology for the last decade. In an attempt to preferably interpret the soil microbiological characteristic variation associated with vegetation restoration and further to explore the role of soil microbiology in vegetation restoration mechanisin of degraded karst regions, we measured microbial biomass C and basal respiration in soils during vegetation restoration in Zhenfeng County of southwestern Guizhou Province,China. The community level physiological profiles (CLPP) of the soil microbial community to were estimated determine if vegetation changes were accompanied by changes in functioning of soil microbial communities. The results showed that soil microbial biomass C and microbial quotient (microbial biomass C/organic C) tended to increase with vegetation restoration, being in the order arboreal community stage > shrubby community stage > herbaceous community stage > bare land stage. Similar trend was found in the change of basal respiration (BR). The metabolic quotient (thc ratio of basal respiration to microbial biomass, qCO2) decreased with vegetation restoration, and remained at a constantly low level in the arboreal community stage. Analyses of the CLPP data indicated that vegetation restoration tended to result in higher average well color development, substrate richness, and functional diversity.Average utilization of specific substrate guilds was highest in the arboreal community stage. Principle component analysis of the CLPP data further indicated that the arboreal community stage was distinctly different from the other three stages. In conclusion,vegetation restoration improved soil microbial biomass C, respiration, and utilization of carbon sources, and decreased qCO2, thus creating better soil conditions, which in turn could promote the restoration of vegetation on degraded karst regions.

  15. Effects of rhizobacteria on the respiration and growth of Cerasus sachalinensis Kom. seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Qin, S.; Zhou, W.; Li, Z.; Lyu, D.

    2016-11-01

    In this study, we investigated the influence of rhizosphere microorganisms on seed germination and root metabolism in Cerasus sachalinensis Kom. We inoculated C. sachalinensis plants with suspensions of dominant bacterial strains isolated from their rhizosphere. Four bacterial strains each with significant growth-promoting or growth-inhibiting effects were screened from the efficient root-colonizing microorganisms. The number of actinomycetes increased and that of fungi decreased significantly in the seedling rhizospheres after rhizobacteria treatment. The growth-promoting bacteria slightly affected the respiration rates and respiratory pathway enzymes, but significantly improved root viability, root carbohydrate concentration and seedling growth. Bacillus cereus, Staphylococcus sp. and Pseudomonas fluorescens were identified as the growth-promoting rhizobacteria; one strain could not be identified. After inoculation with the growth-inhibiting bacteria, the number of fungal colonies in the seedling rhizospheres increased and root viability and respiration rate as well as starch and sucrose accumulation in the roots significantly decreased. The glycolysis, pentose phosphate and alternative oxidase pathways became the major pathways of respiratory metabolism after inoculation with the growth-inhibiting bacteria. The height, leaf number, growth and dry weight of the seedlings decreased significantly in plants inoculated with the growth-inhibiting bacteria. Inoculation of C. sachalinensis rhizosphere with growth-promoting and growth-inhibiting bacteria affected the soil environmental factors such as microbial group composition, nutrient concentration and seedling biomass. (Author)

  16. A rapid in situ respiration test for measuring aerobic biodegradation rates of hydrocarbons in soil.

    Science.gov (United States)

    Hinchee, R E; Ong, S K

    1992-10-01

    An in situ test method to measure the aerobic biodegradation rates of hydrocarbons in contaminated soil is presented. The test method provides an initial assessment of bioventing as a remediation technology for hydrocarbon-contaminated soil. The in situ respiration test consists of ventilating the contaminated soil of the unsaturated zone with air and periodically monitoring the depletion of oxygen (O2) and production of carbon dioxide (CO2) over time after the air is turned off. The test is simple to implement and generally takes about four to five days to complete. The test was applied at eight hydrocarbon-contaminated sites of different geological and climatic conditions. These sites were contaminated with petroleum products or petroleum fuels, except for two sites where the contaminants were primarily polycyclic aromatic hydrocarbons. Oxygen utilization rates for the eight sites ranged from 0.02 to 0.99 percent O2/hour. Estimated biodegradation rates ranged from 0.4 to 19 mg/kg of soil/day. These rates were similar to the biodegradation rates obtained from field and pilot studies using mass balance methods. Estimated biodegradation rates based on O2 utilization were generally more reliable (especially for alkaline soils) than rates based on CO2 production. CO2 produced from microbial respiration was probably converted to carbonate under alkaline conditions.

  17. Effects of rhizobacteria on the respiration and growth of Cerasus sachalinensis Kom. seedlings

    Directory of Open Access Journals (Sweden)

    Sijun Qin

    2016-06-01

    Full Text Available In this study, we investigated the influence of rhizosphere microorganisms on seed germination and root metabolism in Cerasus sachalinensis Kom. We inoculated C. sachalinensis plants with suspensions of dominant bacterial strains isolated from their rhizosphere. Four bacterial strains each with significant growth-promoting or growth-inhibiting effects were screened from the efficient root-colonizing microorganisms. The number of actinomycetes increased and that of fungi decreased significantly in the seedling rhizospheres after rhizobacteria treatment. The growth-promoting bacteria slightly affected the respiration rates and respiratory pathway enzymes, but significantly improved root viability, root carbohydrate concentration and seedling growth. Bacillus cereus, Staphylococcus sp. and Pseudomonas fluorescens were identified as the growth-promoting rhizobacteria; one strain could not be identified. After inoculation with the growth-inhibiting bacteria, the number of fungal colonies in the seedling rhizospheres increased and root viability and respiration rate as well as starch and sucrose accumulation in the roots significantly decreased. The glycolysis, pentose phosphate and alternative oxidase pathways became the major pathways of respiratory metabolism after inoculation with the growth-inhibiting bacteria. The height, leaf number, growth and dry weight of the seedlings decreased significantly in plants inoculated with the growth-inhibiting bacteria. Inoculation of C. sachalinensis rhizosphere with growth-promoting and growth-inhibiting bacteria affected the soil environmental factors such as microbial group composition, nutrient concentration and seedling biomass.

  18. Spatial Distribution of an Uranium-Respiring Betaproteobacterium at the Rifle, CO Field Research Site

    Science.gov (United States)

    Koribanics, Nicole M.; Tuorto, Steven J.; Lopez-Chiaffarelli, Nora; McGuinness, Lora R.; Häggblom, Max M.; Williams, Kenneth H.; Long, Philip E.; Kerkhof, Lee J.

    2015-01-01

    The Department of Energy’s Integrated Field-Scale Subsurface Research Challenge Site (IFRC) at Rifle, Colorado was created to address the gaps in knowledge on the mechanisms and rates of U(VI) bioreduction in alluvial sediments. Previous studies at the Rifle IFRC have linked microbial processes to uranium immobilization during acetate amendment. Several key bacteria believed to be involved in radionuclide containment have been described; however, most of the evidence implicating uranium reduction with specific microbiota has been indirect. Here, we report on the cultivation of a microorganism from the Rifle IFRC that reduces uranium and appears to utilize it as a terminal electron acceptor for respiration with acetate as electron donor. Furthermore, this bacterium constitutes a significant proportion of the subsurface sediment community prior to biostimulation based on TRFLP profiling of 16S rRNA genes. 16S rRNA gene sequence analysis indicates that the microorganism is a betaproteobacterium with a high similarity to Burkholderia fungorum. This is, to our knowledge, the first report of a betaproteobacterium capable of uranium respiration. Our results indicate that this microorganism occurs commonly in alluvial sediments located between 3-6 m below ground surface at Rifle and may play a role in the initial reduction of uranium at the site. PMID:25874721

  19. Respiration and sodium transport in rabbit urinary bladder.

    Science.gov (United States)

    Silverthorn, S U; Eaton, D C

    1982-07-28

    Respiration of rabbit urinary bladder was measured in free-floating pieces and in short-circuited pieces mounted in an Ussing chamber. Ouabain, amiloride, and potassium-free saline inhibited respiration approx. 20%; sodium-free saline depressed respiration approx. 40-50%. The coupling ratio between respiration and transport in short-circuited tissues was about two sodium ions per molecule O2. Chloride-free saline depressed mean oxygen consumption 21% in free-floating tissue pieces; 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) and furosemide had no effect. The effect of chloride-free saline in short-circuited tissues was variable; in tissues with low transport rates, respiration was stimulated about 21% while in tissue with high transport rates respiration was reduced about 24%. Nystatin and monensin, both of which markedly increase the conductance of cell membranes with a concomitant increase in sodium entry, stimulated respiration. These data indicate that 50-60% of the total oxygen consumption is not influenced by sodium, 20-25% is linked to (Na+ +K+)-ATPase transport, while the remaining 25-30% is sodium-dependent but not ouabain-inhibitable.

  20. Plankton Respiration from the Cellular to the Basin Scale

    Science.gov (United States)

    Robinson, C.; Garcia-Martin, E. E.; Hull, T.; Kitidis, V. A.; Ostle, C.; Serret, P.; Tilstone, G.

    2016-02-01

    Estimates of marine plankton respiration provide an important constraint on the magnitude of the biological carbon pump and global elemental nutrient cycles, yet respiration remains one of the least constrained terms in models of metabolism, gas exchange and carbon mass balance. This is due in part to the difficulty in measuring both total oceanic respiration and that attributable to specific plankton groups or size classes and the resulting lack of earth observation algorithms. Respiration in the surface layer of the ocean is usually estimated from either the consumption of dissolved oxygen in a contained sample volume or from enzymatic proxies such as INT, and is less frequently determined from mixed layer oxygen utilisation, allometric equations or biomass / abundance spectra.As part of a tracer release (SF6) experiment in the Mauritanian upwelling and a seasonal study of UK shelf sea biogeochemistry, we measured plankton respiration using a range of methods which span time and space scales from cells to the mixed layer and hours to years. This presentation will compare and contrast these concurrent measurements with a view to assessing the range of variability in respiration relative to that in primary production alongside measures of parameters such as plankton community structure and organic carbon availability which may lead to this variability. In addition, by comparing between systems and between seasons in the same system, and utilising the available global dataset, we aim to test predictive empirical models of respiration in an attempt to extrapolate to the basin scale.

  1. Soil Respiration in Semiarid Temperate Grasslands under Various Land Management.

    Science.gov (United States)

    Wang, Zhen; Ji, Lei; Hou, Xiangyang; Schellenberg, Michael P

    2016-01-01

    Soil respiration, a major component of the global carbon cycle, is significantly influenced by land management practices. Grasslands are potentially a major sink for carbon, but can also be a source. Here, we investigated the potential effect of land management (grazing, clipping, and ungrazed enclosures) on soil respiration in the semiarid grassland of northern China. Our results showed the mean soil respiration was significantly higher under enclosures (2.17 μmol.m(-2).s(-1)) and clipping (2.06 μmol.m(-2).s(-1)) than under grazing (1.65 μmol.m-(2).s(-1)) over the three growing seasons. The high rates of soil respiration under enclosure and clipping were associated with the higher belowground net primary productivity (BNPP). Our analyses indicated that soil respiration was primarily related to BNPP under grazing, to soil water content under clipping. Using structural equation models, we found that soil water content, aboveground net primary productivity (ANPP) and BNPP regulated soil respiration, with soil water content as the predominant factor. Our findings highlight that management-induced changes in abiotic (soil temperature and soil water content) and biotic (ANPP and BNPP) factors regulate soil respiration in the semiarid temperate grassland of northern China.

  2. Alternative respiration and fumaric acid production of Rhizopus oryzae.

    Science.gov (United States)

    Gu, Shuai; Xu, Qing; Huang, He; Li, Shuang

    2014-06-01

    Under the conditions of fumaric acid fermentation, Rhizopus oryzae ME-F14 possessed at least two respiratory systems. The respiration of mycelia was partially inhibited by the cytochrome respiration inhibitor antimycin A or the alternative respiration inhibitor salicylhydroxamic acid and was completely inhibited in the presence of both antimycin A and salicylhydroxamic acid. During fumaric acid fermentation process, the activity of alternative respiration had a great correlation with fumaric acid productivity; both of them reached peak at the same time. The alternative oxidase gene, which encoded the mitochondrial alternative oxidase responsible for alternative respiration in R. oryzae ME-F14, was cloned and characterized in Escherichia coli. The activity of alternative respiration, the alternative oxidase gene transcription level, as well as the fumaric acid titer were measured under different carbon sources and different carbon-nitrogen ratios. The activity of alternative respiration was found to be comparable to the transcription level of the alternative oxidase gene and the fumaric acid titer. These results indicated that the activity of the alternative oxidase was regulated at the transcription stage under the conditions tested for R. oryzae ME-F14.

  3. Temperature sensitivity of soil respiration is dependent on readily decomposable C substrate concentration

    Directory of Open Access Journals (Sweden)

    A. A. Larionova

    2007-06-01

    Full Text Available Temperature acclimation of soil organic matter (SOM decomposition is one of the major uncertainties in predicting soil CO2 efflux by the increase in global mean temperature. A reasonable explanation for an apparent acclimation proposed by Davidson and colleagues (2006 based on Michaelis-Menten kinetics suggests that temperature sensitivity decreases when both maximal activity of respiratory enzymes (Vmax and half- saturation constant (Ks cancel each other upon temperature increase. We tested the hypothesis of the canceling effect by the mathematical simulation of the data obtained in the incubation experiments with forest and arable soils. Our data confirm the hypothesis and suggest that concentration of readily decomposable C substrate as glucose equivalent is an important factor controlling temperature sensitivity. The highest temperature sensitivity was observed when C substrate concentration was much lower than Ks. Increase of substrate content to the half-saturation constant resulted in temperature acclimation associated with the canceling effect. Addition of the substrate to the level providing respiration at a maximal rate Vmax leads to the acclimation of the whole microbial community as such. However, growing microbial biomass was more sensitive to the temperature alterations. This study improves our understanding of the instability of temperature sensitivity of soil respiration under field conditions, explaining this phenomenon by changes in concentration of readily decomposable C substrate. It is worth noting that this pattern works regardless of the origin of C substrate: production by SOM decomposition, release into the soil by rhizodeposition, litter fall or drying-rewetting events.

  4. Potential importance of physiologically diverse benthic foraminifera in sedimentary nitrate storage and respiration

    Science.gov (United States)

    Bernhard, Joan M.; Casciotti, Karen L.; McIlvin, Matthew R.; Beaudoin, David J.; Visscher, Pieter T.; Edgcomb, Virginia P.

    2012-09-01

    Until recently, the process of denitrification (conversion of nitrate or nitrite to gaseous products) was thought to be performed exclusively by prokaryotes and fungi. The finding that foraminifera perform complete denitrification could impact our understanding of nitrate removal in sediments as well as our understanding of eukaryotic respiration, especially if it is widespread. However, details of this process and the subcellular location of these reactions in foraminifera remain uncertain. For example, prokaryotic endobionts, rather than the foraminifer proper, could perform denitrification, as has been shown recently in an allogromiid foraminifer. Here, intracellular nitrate concentrations and isotope ratios (δ15NNO3 and δ18ONO3) were measured to assess the nitrate dynamics in four benthic foraminiferal species (Bolivina argentea, Buliminella tenuata, Fursenkoina cornuta, Nonionella stella) with differing cellular architecture and associations with microbial endobionts, recovered from Santa Barbara Basin, California. Cellular nitrate concentrations were high (12-217 mM) in each species, and intracellular nitrate often had elevated δ15NNO3 and δ18ONO3 values. Experiments including suboxic and anoxic incubations of B. argentea revealed a decrease in intracellular nitrate concentration and an increase in δ15NNO3 and δ18ONO3over time, indicating nitrate respiration and/or denitrification within the foraminifera. Results illustrate that nitrate reduction occurs in a range of foraminiferal species, including some possessing endobionts (including a chloroplast-sequestering species) and others lacking endobionts, implying that microbial associates may not solely be responsible for this process in foraminifera. Furthermore, we show that benthic foraminifera may represent important reservoirs of nitrate storage in sediments, as well as mediators of its removal.

  5. Microfluidics and microbial engineering.

    Science.gov (United States)

    Kou, Songzi; Cheng, Danhui; Sun, Fei; Hsing, I-Ming

    2016-02-01

    The combination of microbial engineering and microfluidics is synergistic in nature. For example, microfluidics is benefiting from the outcome of microbial engineering and many reported point-of-care microfluidic devices employ engineered microbes as functional parts for the microsystems. In addition, microbial engineering is facilitated by various microfluidic techniques, due to their inherent strength in high-throughput screening and miniaturization. In this review article, we firstly examine the applications of engineered microbes for toxicity detection, biosensing, and motion generation in microfluidic platforms. Secondly, we look into how microfluidic technologies facilitate the upstream and downstream processes of microbial engineering, including DNA recombination, transformation, target microbe selection, mutant characterization, and microbial function analysis. Thirdly, we highlight an emerging concept in microbial engineering, namely, microbial consortium engineering, where the behavior of a multicultural microbial community rather than that of a single cell/species is delineated. Integrating the disciplines of microfluidics and microbial engineering opens up many new opportunities, for example in diagnostics, engineering of microbial motors, development of portable devices for genetics, high throughput characterization of genetic mutants, isolation and identification of rare/unculturable microbial species, single-cell analysis with high spatio-temporal resolution, and exploration of natural microbial communities.

  6. Childhood microbial keratitis

    Directory of Open Access Journals (Sweden)

    Abdullah G Al Otaibi

    2012-01-01

    Conclusion: Children with suspected microbial keratitis require comprehensive evaluation and management. Early recognition, identifying the predisposing factors and etiological microbial organisms, and instituting appropriate treatment measures have a crucial role in outcome. Ocular trauma was the leading cause of childhood microbial keratitis in our study.

  7. Students’ Perception of HR Competencies

    National Research Council Canada - National Science Library

    Vesna Novak; Anja Žnidaršič; Polona Šprajc

    2015-01-01

    ...) to present the role of competencies in human resource management. The aim of this paper is to examine the human resource competencies among students, and their judgments regarding the competencies they have already received during their studies...

  8. Microbial fuel cells: Their application and microbiology

    Science.gov (United States)

    He, Zhen

    The energy crisis is an urgent global issue due to the increased consumption of the finite amount of fossil fuel. As a result, looking for alternative energy sources is of critical importance. Microbial fuel cell (MFC) technology can extract electric energy from wastewater, and thus is a sustainable approach to supply energy to our electricity-based society. My research focuses on the development of a suitable MFC reactor for wastewater treatment and the understanding of the microbial function in the MFC process. First, together with colleagues, I have developed a novel MFC reactor, named upflow microbial fuel cell (UMFC), by combining upflow and MFC technologies. The power output from the UMFC was improved by 10-fold after it was modified with a U-shape cathode. The UMFC appears to be a practical reactor for continuous operation, though the output of electric power requires further improvement. In addition, a sediment MFC with a rotating cathode was also developed and its performance was examined. Second, I have adopted a human distal gut anaerobe, Bacteroides thetaiotaomicron, as the model organism to study the role of fermentative bacterium in electricity generation. When B. thetaiotaomicron grew under an applied electric potential, an electric current was generated. GeneChip data indicated that this bacterium did not alter its metabolism during this process. Although B. thetaiotaomicron may not be capable of respiration with an electrode as the electron acceptor, the experiment has demonstrated that fermentative bacteria may play an important role in electricity generation.

  9. Controls upon microbial accessibility to soil organic matter following woody plant encroachment into grasslands

    Science.gov (United States)

    Creamer, C. A.; Boutton, T. W.; Filley, T. R.

    2009-12-01

    Woody plant encroachment (WPE) into savannas and grasslands is a global phenomenon that alters soil organic matter (SOM) dynamics through changes in litter quality and quantity, soil structure, microbial ecology, and soil hydrology. To elucidate the controls upon microbial accessibility to SOM, bulk soils from a chronosequence of progressive WPE into native grasslands at the Texas A&M Agricultural Experimental Station La Copita Research Area were incubated for one year. The quantity and stable carbon isotope composition of respired CO2, plant biopolymer chemistry in SOM, and microbial community structure were tracked. Respiration rates declined steadily over the course of the experiment with 15-25% of the total CO2 respired released in the first month of incubation. Between 8 and 18% of the total carbon was mineralized to CO2 throughout the incubation. After day 84 a significantly (p cutin and suberin, as hypothesized by others. Quantitative and isotopic comparisons of these monomers prior to and following the incubation will determine if selective compound utilization is a reason for this depletion. The results discussed herein provide important insights into the dynamics of SOM accrual with WPE as well as respiration dynamics during laboratory incubations.

  10. Temperature response of soil respiration largely unaltered with experimental warming.

    Science.gov (United States)

    Carey, Joanna C; Tang, Jianwu; Templer, Pamela H; Kroeger, Kevin D; Crowther, Thomas W; Burton, Andrew J; Dukes, Jeffrey S; Emmett, Bridget; Frey, Serita D; Heskel, Mary A; Jiang, Lifen; Machmuller, Megan B; Mohan, Jacqueline; Panetta, Anne Marie; Reich, Peter B; Reinsch, Sabine; Wang, Xin; Allison, Steven D; Bamminger, Chris; Bridgham, Scott; Collins, Scott L; de Dato, Giovanbattista; Eddy, William C; Enquist, Brian J; Estiarte, Marc; Harte, John; Henderson, Amanda; Johnson, Bart R; Larsen, Klaus Steenberg; Luo, Yiqi; Marhan, Sven; Melillo, Jerry M; Peñuelas, Josep; Pfeifer-Meister, Laurel; Poll, Christian; Rastetter, Edward; Reinmann, Andrew B; Reynolds, Lorien L; Schmidt, Inger K; Shaver, Gaius R; Strong, Aaron L; Suseela, Vidya; Tietema, Albert

    2016-11-29

    The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

  11. On Verbal Competence

    Directory of Open Access Journals (Sweden)

    Zhongxin Dai

    2014-04-01

    Full Text Available This paper explored a new concept, verbal competence, to present a challenge to Chomsky’s linguistic competence and Hymes’ communicative competence. It is generally acknowledged that Chomsky concerned himself only with the syntactic/grammatical structures, and viewed the speaker’s generation and transformation of syntactic structures as the production of language. Hymes challenged Chomsky’s conception of linguistic competence and argued for an ethnographic or sociolinguistic concept, communicative competence, but his concept is too broad to be adequately grasped and followed in such fields as linguistics and second language acquisition. Communicative competence can include abilities to communicate with nonverbal behaviors, e.g. gestures, postures or even silence. The concept of verbal competence concerns itself with the mental and psychological processes of verbal production in communication. These processes originate from the speaker’s personal experience, in a certain situation of human communication, and with the sudden appearance of the intentional notion, shape up as the meaning images and end up in the verbal expression.

  12. The cytological implications of primary respiration.

    Science.gov (United States)

    Crisera, P N

    2001-01-01

    Observing the macroscopic complexities of evolved species, the exceptional continuity that occurs among different cells, tissues and organs to respond coherently to the proper set of stimuli as a function of self/species survival is appreciable. Accordingly, it alludes to a central rhythm that resonates throughout the cell; nominated here as primary respiration (PR), which is capable of binding and synchronizing a diversity of physiological processes into a functional biological unity. Phylogenetically, it was conserved as an indispensable element in the makeup of the subkingdom Metazoa, since these species require a high degree of coordination among the different cells that form their body. However, it does not preclude the possibility of a basal rhythm to orchestrate the intricacies of cellular dynamics of both prokaryotic and eukaryotic cells. In all probability, PR emerges within the crucial organelles, with special emphasis on the DNA (5), and propagated and transduced within the infrastructure of the cytoskeleton as wave harmonics (49). Collectively, this equivalent vibration for the subphylum Vertebrata emanates as craniosacral respiration (CSR), though its expression is more elaborate depending on the development of the CNS. Furthermore, the author suggests that the phenomenon of PR or CSR be intimately associated to the basic rest/activity cycle (BRAC), generated by concentrically localized neurons that possess auto-oscillatory properties and assembled into a vital network (39). Historically, during Protochordate-Vertebrate transition, this area circumscribes an archaic region of the brain in which many vital biological rhythms have their source, called hindbrain rhombomeres. Bass and Baker (2) propose that pattern-generating circuits of more recent innovations, such as vocal, electromotor, extensor muscle tonicity, locomotion and the extraocular system, have their origin from the same Hox gene-specified compartments of the embryonic hindbrain (rhombomeres

  13. Limited recovery of soil microbial activity after transient exposure to gasoline vapors

    DEFF Research Database (Denmark)

    Modrzyński, Jakub J.; Christensen, Jan H.; Mayer, Philipp

    2016-01-01

    During gasoline spills complex mixtures of toxic volatile organic compounds (VOCs) are released to terrestrial environments. Gasoline VOCs exert baseline toxicity (narcosis) and may thus broadly affect soil biota. We assessed the functional resilience (i.e. resistance and recovery of microbial...... functions) in soil microbial communities transiently exposed to gasoline vapors by passive dosing via headspace for 40 days followed by a recovery phase of 84 days. Chemical exposure was characterized with GC-MS, whereas microbial activity was monitored as soil respiration (CO2 release) and soil bacterial...... microbial activity indicating residual soil toxicity, which could not be attributed to BTEX, but rather to mixture toxicity of more persistent gasoline constituents or degradation products. Our results indicate a limited potential for functional recovery of soil microbial communities after transient...

  14. Leadership Competences Among Managers

    Directory of Open Access Journals (Sweden)

    Anna Baczynska

    2017-06-01

    Full Text Available Purpose: The aim of this paper is to present the results of a survey conducted among managers (N=38 in the framework of the project “Development of the Bounded Leadership Theory”. The research juxtaposes two types of variables: (1 leadership competencies outlined in Kozminski’s theory (i.e. anticipatory, visionary, value-creating, mobilizing, self-reflection with (2 three psychological predispositions of leaders, such as intelligence, personality and ability to influence others. The tested predispositions represented three groups: non-variable traits, or permanent characteristics (intelligence, partially variable characteristics (personality and variable characteristics (influence tactics. Methodology: A total of 38 middle and senior managers, students of the MBA programme at Kozminski University, took part in the survey. Participants flled out a preliminary version of the Leadership Competence Questionnaire, as well as tests pertaining to intelligence, personality and influence tactics. The hypotheses were tested using Spearman’s rho correlation. The research has brought interesting results relating to the correlation between the fve tested competencies and leadership predispositions. Findings: Permanent and partly stable characteristics do not correlate with leadership competencies, i.e. a high score in leadership competencies is not necessarily synonymous with high intelligence levels or positive personality traits. Correlations have been observed between mobilization skills and influence tactics in the surveyed sample, i.e. legitimacy and personal appeals that leaders have recourse to and, in the case of value-creating competencies, an interesting correlation with legitimacy. Originality: The study constitutes an important contribution to the extant literature, as – first and foremost – it represents a new approach to the understanding of leadership competencies. Secondly, it reveals correlations between complex skills, i

  15. Wood and foliar respiration of tropical wet forest environment

    Science.gov (United States)

    Asao, S.; Bedoya Arrieta, R.; Ryan, M. G.

    2011-12-01

    Wood and foliar respiration from tropical forests constitute major components of ecosystem respiration that may control their productivity and carbon storage. However, few estimates on tropical forests vary greatly. Furthermore, the trees in these forests respire great amounts of carbon, but impacts of individual tree species on respiration is not well known. We examined wood and foliar respiration in this environment in relation to individual tree species. The objectives of this study were to: 1) identify how respiration rates relate to scaling variables for wood and foliage, 2) examine the effects of individual tree species on these relationships, 3) extrapolate the rates to the annual fluxes of the whole stands, and 4) determine if tree species differed in these fluxes. Established on an abandoned pasture in 1988 at La Selva Biological Station in Costa Rica, the monodominant stands contained four native species in a complete randomized block design. Respiration rates based on tissue surface area ranged among dominant tree species from 0.6 to 1.0 μg C m^-2 s^-1 for small diameter wood (<10cm), 1.0 to 1.8 μg C m^-2 s^-1 for large diameter wood, and 0.7 to 0.8 μg C m^-2 s^-1 for foliage. Understory species had similar wood respiration rates, but foliage respiration rates were about half of those for canopy leaves. Among surface area, volume, or biomass, respiration rates scaled best with surface area for wood with small diameter, volume or biomass for large diameter wood, and leaf area for foliage. These relationships differed slightly among tree species and between canopy trees and understory species. Foliar respiration rate was generally related to leaf nitrogen content, and this relationship differed among dominant tree species. Temperature response of foliar respiration also differed among tree species and canopy class. However, daily and annual temperature fluctuations had less than 3% effect on annual flux. Annual respiratory fluxes from wood and foliage

  16. Estimating daytime ecosystem respiration from eddy-flux data

    DEFF Research Database (Denmark)

    Bruhn, Dan; Mikkelsen, Teis Nørgaard; Herbst, Mathias

    2011-01-01

    To understand what governs the patterns of net ecosystem exchange of CO2, an understanding of factors influencing the component fluxes, ecosystem respiration and gross primary production is needed. In the present paper, we introduce an alternative method for estimating daytime ecosystem respiration...... based on whole ecosystem fluxes from a linear regression of photosynthetic photon flux density data vs. daytime net ecosystem exchange data at forest ecosystem level. This method is based on the principles of the Kok-method applied at leaf level for estimating daytime respiration. We demonstrate...... the method with field data and provide a discussion of the limitations of the method....

  17. Competence development in UAS

    DEFF Research Database (Denmark)

    Thorslund, Jørgen; Brodersen, Anne Mygind

    2011-01-01

    As a University of Applied Science (UAS) University College Lillebaelt in Denmark is addressing education, knowledge production and professional development in perspective of life-long and life-wide learning. It is our basic assumption that that internal competence development ? individually...... and organizationally - among UAS educators should be based on same learning concepts as used in professional development to avoid parallelism. Do for yourself, what you preach for others. Second, competence development of faculty is a central element in transformation of our institutions from schools of higher...... education to universities of applied science (UAS). Competence development strategies should thus include objectives for the institutions ability to contribute to knowledge production....

  18. Building Project Competence

    DEFF Research Database (Denmark)

    Pemsel, Sofia; Wiewiora, Anna

    This research investigates the development of project competence, and particularly, three related dynamic capabilities (shifting, adapting, leveraging) that contribute to project competence development. In doing so, we make use of the emerging literature on knowledge governance and theorize how...... knowledge governance mechanisms can move the organization towards desired knowledge-based goals. A multiple-case study comprising 23 cases advances our understanding of the elements that trigger, enable, hamper, and drive shifting, leveraging and adapting. Finally, the paper offers a tentative framework...... of dynamic capability building promoting project competence development....

  19. Evaluation of respiration in compost landfill biocovers intended for methane oxidation

    DEFF Research Database (Denmark)

    Scheutz, Charlotte; Pedicone, Alessio; Pedersen, Gitte Bukh

    2011-01-01

    will compete for O2 with other aerobic microorganisms. If the compost is not mature, a significant portion of the O2 diffusing into the compost layer will be consumed by non-methanotrophs, thereby limiting CH4 oxidation. The results of this study however also suggest that the consumption of O2 in the compost......A low-cost alternative approach to reduce landfill gas (LFG) emissions is to integrate compost into the landfill cover design in order to establish a biocover that is optimized for biological oxidation of methane (CH4). A laboratory and field investigation was performed to quantify respiration...... in an experimental compost biocover in terms of oxygen (O2) consumption and carbon dioxide (CO2) production and emission rates. O2 consumption and CO2 production rates were measured in batch and column experiments containing compost sampled from a landfill biowindow at Fakse landfill in Denmark. Column gas...

  20. Association of microbial community composition and activity with lead, chromium, and hydrocarbon contamination.

    Science.gov (United States)

    Shi, W; Becker, J; Bischoff, M; Turco, R F; Konopka, A E

    2002-08-01

    Microbial community composition and activity were characterized in soil contaminated with lead (Pb), chromium (Cr), and hydrocarbons. Contaminant levels were very heterogeneous and ranged from 50 to 16,700 mg of total petroleum hydrocarbons (TPH) kg of soil(-1), 3 to 3,300 mg of total Cr kg of soil(-1), and 1 to 17,100 mg of Pb kg of soil(-1). Microbial community compositions were estimated from the patterns of phospholipid fatty acids (PLFA); these were considerably different among the 14 soil samples. Statistical analyses suggested that the variation in PLFA was more correlated with soil hydrocarbons than with the levels of Cr and Pb. The metal sensitivity of the microbial community was determined by extracting bacteria from soil and measuring [(3)H]leucine incorporation as a function of metal concentration. Six soil samples collected in the spring of 1999 had IC(50) values (the heavy metal concentrations giving 50% reduction of microbial activity) of approximately 2.5 mM for CrO(4)2- and 0.01 mM for Pb2+. Much higher levels of Pb were required to inhibit [14C]glucose mineralization directly in soils. In microcosm experiments with these samples, microbial biomass and the ratio of microbial biomass to soil organic C were not correlated with the concentrations of hydrocarbons and heavy metals. However, microbial C respiration in samples with a higher level of hydrocarbons differed from the other soils no matter whether complex organic C (alfalfa) was added or not. The ratios of microbial C respiration to microbial biomass differed significantly among the soil samples (P < 0.05) and were relatively high in soils contaminated with hydrocarbons or heavy metals. Our results suggest that the soil microbial community was predominantly affected by hydrocarbons.

  1. Changes in the Size of the Active Microbial Pool Explain Short-Term Soil Respiratory Responses to Temperature and Moisture.

    Science.gov (United States)

    Salazar-Villegas, Alejandro; Blagodatskaya, Evgenia; Dukes, Jeffrey S

    2016-01-01

    Heterotrophic respiration contributes a substantial fraction of the carbon flux from soil to atmosphere, and responds strongly to environmental conditions. However, the mechanisms through which short-term changes in environmental conditions affect microbial respiration still remain unclear. Microorganisms cope with adverse environmental conditions by transitioning into and out of dormancy, a state in which they minimize rates of metabolism and respiration. These transitions are poorly characterized in soil and are generally omitted from decomposition models. Most current approaches to model microbial control over soil CO2 production relate responses to total microbial biomass (TMB) and do not differentiate between microorganisms in active and dormant physiological states. Indeed, few data for active microbial biomass (AMB) exist with which to compare model output. Here, we tested the hypothesis that differences in soil microbial respiration rates across various environmental conditions are more closely related to differences in AMB (e.g., due to activation of dormant microorganisms) than in TMB. We measured basal respiration (SBR) of soil incubated for a week at two temperatures (24 and 33°C) and two moisture levels (10 and 20% soil dry weight [SDW]), and then determined TMB, AMB, microbial specific growth rate, and the lag time before microbial growth (t lag ) using the Substrate-Induced Growth Response (SIGR) method. As expected, SBR was more strongly correlated with AMB than with TMB. This relationship indicated that each g active biomass C contributed ~0.04 g CO2-C h(-1) of SBR. TMB responded very little to short-term changes in temperature and soil moisture and did not explain differences in SBR among the treatments. Maximum specific growth rate did not respond to environmental conditions, suggesting that the dominant microbial populations remained similar. However, warmer temperatures and increased soil moisture both reduced t lag , indicating that favorable

  2. Response of respiration and nutrient availability to drying and rewetting in soil from a semi-arid woodland depends on vegetation patch and a recent wildfire

    Science.gov (United States)

    Sun, Q.; Meyer, W. S.; Koerber, G. R.; Marschner, P.

    2015-08-01

    Semi-arid woodlands, which are characterised by patchy vegetation interspersed with bare, open areas, are frequently exposed to wildfire. During summer, long dry periods are occasionally interrupted by rainfall events. It is well known that rewetting of dry soil induces a flush of respiration. However, the magnitude of the flush may differ between vegetation patches and open areas because of different organic matter content, which could be further modulated by wildfire. Soils were collected from under trees, under shrubs or in open areas in unburnt and burnt sandy mallee woodland, where part of the woodland experienced a wildfire which destroyed or damaged most of the aboveground plant parts 4 months before sampling. In an incubation experiment, the soils were exposed to two moisture treatments: constantly moist (CM) and drying and rewetting (DRW). In CM, soils were incubated at 80 % of maximum water holding capacity (WHC) for 19 days; in DRW, soils were dried for 4 days, kept dry for another 5 days, then rewetted to 80 % WHC and maintained at this water content until day 19. Soil respiration decreased during drying and was very low in the dry period; rewetting induced a respiration flush. Compared to soil under shrubs and in open areas, cumulative respiration per gram of soil in CM and DRW was greater under trees, but lower when expressed per gram of total organic carbon (TOC). Organic matter content, available P, and microbial biomass C, but not available N, were greater under trees than in open areas. Wild fire decreased the flush of respiration per gram of TOC in the open areas and under shrubs, and reduced TOC and microbial biomass C (MBC) concentrations only under trees, but had little effect on available N and P concentrations. We conclude that the impact of wildfire and DRW events on nutrient cycling differs among vegetation patches of a native semi-arid woodland which is related to organic matter amount and availability.

  3. Production competence revisited

    DEFF Research Database (Denmark)

    Szász, Levente; Demeter, Krisztina; Boer, Harry

    2015-01-01

    Purpose – The purpose of this paper is to seek remedy to two major flaws of the production competence literature, which concern: the way the production competence construct is operationalized and the way its effects on performance are measured. Design/methodology/approach – The paper proposes...... to measure production competence as the two-dimensional operational level construct it actually is, and to use Slack’s (1994) importance performance matrix to study its business level performance effects. The three hypotheses developed are tested using a subsample of the International Manufacturing Strategy...... Survey database, which includes 465 manufacturing companies from 21 countries. Findings – The study offers additional empirical support for production competence theory. Going beyond supporting existing theory, the results give more detailed insight by indicating that low operational performance on even...

  4. Competence, governance, and entrepreneurship

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Mahnke, Volker

    , what determines their boundaries and internal organization), but would also be helpful for informing strategy issues, such as understanding strategic flexibility, strategic options, and the sources of competitive advantage. This volume brings together prominent voices on competence, governance...

  5. Designing for competences

    DEFF Research Database (Denmark)

    Christiansen, Rene B; Gundersen, Peter Bukovica

    2014-01-01

    of these professionals has changed - and has become more cross-professional, more complex and analytic and reflective competencies have entered the policy papers of these human-professions as central, important forms of knowledge. These bachelor degrees in Denmark within the field of education (teaching and preschool...... and generating solutions in the form of design principles when moving from a focus of knowledge to a focus of competences....

  6. Effects of butachlor on microbial enzyme activities in paddy soil.

    Science.gov (United States)

    Min, Hang; Ye, Yang-Fang; Chen, Zhong-Yun; Wu, Wei-Xiang; Du, Yu-Feng

    2002-07-01

    This paper reports the influences of the herbicide butachlor (n-butoxymethl-chloro-2', 6'-diethylacetnilide) on microbial respiration, nitrogen fixation and nitrification, and on the activities of dehydrogenase and hydrogen peroxidase in paddy soil. The results showed that after application of butachlor with concentrations of 5.5 micrograms/g dried soil, 11.0 micrograms/g dried soil and 22.0 micrograms/g dried soil, the application of butachlor enhanced the activity of dehydrogenase at increasing concentrations. The soil dehydrogenase showed the highest activity on the 16th day after application of 22.0 micrograms/g dried soil of butachlor. The hydrogen peroxidase could be stimulated by butachlor. The soil respiration was depressed within a period from several days to more than 20 days, depending on concentrations of butachlor applied. Both the nitrogen fixation and nitrification were stimulated in the beginning but reduced greatly afterwards in paddy soil.

  7. Characterization of respirable mine dust and diesel particulate matter

    CSIR Research Space (South Africa)

    Mahlangu, Vusi J

    2015-11-01

    Full Text Available This paper presents the preliminary outcomes to develop and optimize methods to characterize DPM and respirable dust samples for the following: Crystalline compounds Common mineral analyses Particle size distribution Elemental Carbon (EC...

  8. Thoracic and respirable particle definitions for human health risk assessment

    Science.gov (United States)

    Provides estimates of the thoracic and respirable fractions, for adults and children during typical activities during both nasal and oral inhalation, that may be used in the design of experimental studies and interpretation of evidence of health effects.

  9. Cellular respiration: the nexus of stress, condition, and ornamentation

    National Research Council Canada - National Science Library

    Hill, Geoffrey E

    2014-01-01

    .... Here, I propose that efficiency of cellular respiration, as a product of mitochondrial function, underlies the associations between ornamentation and performance for a broad range of traits across taxa...

  10. Temperature response of soil respiration largely unaltered with experimental warming

    DEFF Research Database (Denmark)

    Carey, Joanna C; Tang, Jianwu; Templer, Pamela H

    2016-01-01

    considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic......The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific...... attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies...

  11. Metaphorical Competence: A Neglected Component of Communicative Competence

    Directory of Open Access Journals (Sweden)

    Masoud Khalili Sabet

    2016-01-01

    Full Text Available The ability to comprehend and use metaphors in L2 which is referred to as metaphorical competence is an important issue in second language acquisition. Metaphors are so pervasive in our life that we might not realize their presence and simply neglect them even in our first language. Different models of communicative competence have been suggested in the literature; however, the model of Bachman and Palmer (1996 is the one considered in the present study. It includes two major nodes of organizational and pragmatic competences. Under the organizational competence are grammatical and textual competences, and pragmatic competence includes illocutionary and sociolinguistic competences. In this paper it is argued that among the many competences required to be considered proficient in a language, metaphorical competence is also central. As such, after illuminating the concept of metaphor and metaphorical competence, some models of communicative competence (CC are presented. Moreover, in line with Littlemore and Low (2006, it is emphasized that metaphorical competence which is present in most of the components of CC should receive more attention in L2 classrooms. In fact, it is concluded that having an acceptable metaphorical competence contributes to the learners’ overall communicative competence. Keywords: Metaphor, Metaphorical competence, Communicative competence, L2

  12. Soil microbial community and its interaction with soil carbon and nitrogen dynamics following afforestation in central China.

    Science.gov (United States)

    Deng, Qi; Cheng, Xiaoli; Hui, Dafeng; Zhang, Qian; Li, Ming; Zhang, Quanfa

    2016-01-15

    Afforestation may alter soil microbial community structure and function, and further affect soil carbon (C) and nitrogen (N) dynamics. Here we investigated soil microbial carbon and nitrogen (MBC and MBN) and microbial community [e.g. bacteria (B), fungi (F)] derived from phospholipid fatty acids (PLFAs) analysis in afforested (implementing woodland and shrubland plantations) and adjacent croplands in central China. Relationships of microbial properties with biotic factors [litter, fine root, soil organic carbon (SOC), total nitrogen (TN) and inorganic N], abiotic factors (soil temperature, moisture and pH), and major biological processes [basal microbial respiration, microbial metabolic quotient (qCO2), net N mineralization and nitrification] were developed. Afforested soils had higher mean MBC, MBN and MBN:TN ratios than the croplands due to an increase in litter input, but had lower MBC:SOC ratio resulting from low-quality (higher C:N ratio) litter. Afforested soils also had higher F:B ratio, which was probably attributed to higher C:N ratios in litter and soil, and shifts of soil inorganic N forms, water, pH and disturbance. Alterations in soil microbial biomass and community structure following afforestation were associated with declines in basal microbial respiration, qCO2, net N mineralization and nitrification, which likely maintained higher soil carbon and nitrogen storage and stability.

  13. Allelopathy-mediated competition in microbial mats from Antarctic lakes.

    Science.gov (United States)

    Slattery, Marc; Lesser, Michael P

    2017-05-01

    Microbial mats are vertically stratified communities that host a complex consortium of microorganisms, dominated by cyanobacteria, which compete for available nutrients and environmental niches, within these extreme habitats. The Antarctic Dry Valleys near McMurdo Sound include a series of lakes within the drainage basin that are bisected by glacial traverses. These lakes are traditionally independent, but recent increases in glacial melting have allowed two lakes (Chad and Hoare) to become connected by a meltwater stream. Microbial mats were collected from these lakes, and cultured under identical conditions at the McMurdo Station laboratory. Replicate pairings of the microbial mats exhibited consistent patterns of growth inhibition indicative of competitive dominance. Natural products were extracted from the microbial mats, and a disk diffusion assay was utilized to show that allelochemical compounds mediate competitive interactions. Both microscopy and 16S rRNA sequencing show that these mats contain significant populations of cyanobacteria known to produce allelochemicals. Two compounds were isolated from these microbial mats that might be important in the chemical ecology of these psychrophiles. In other disk:mat pairings, including extract versus mat of origin, the allelochemicals exhibited no effect. Taken together, these results indicate that Antarctic lake microbial mats can compete via allelopathy. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Tai Chi training reduced coupling between respiration and postural control.

    Science.gov (United States)

    Holmes, Matthew L; Manor, Brad; Hsieh, Wan-hsin; Hu, Kun; Lipsitz, Lewis A; Li, Li

    2016-01-01

    In order to maintain stable upright stance, the postural control system must account for the continuous perturbations to the body's center-of-mass including those caused by spontaneous respiration. Both aging and disease increase "posturo-respiratory synchronization;" which reflects the degree to which respiration affects postural sway fluctuations over time. Tai Chi training emphasizes the coordination of respiration and bodily movements and may therefore optimize the functional interaction between these two systems. The purpose of the project was to examine the effect of Tai Chi training on the interaction between respiration and postural control in older adults. We hypothesized that Tai Chi training would improve the ability of the postural control system to compensate for respiratory perturbations and thus, reduce posturo-respiratory synchronization. Participants were recruited from supportive housing facilities and randomized to a 12-week Tai Chi intervention (n=28; 86 ± 5 yrs) or educational-control program (n=34, 85 ± 6 yrs). Standing postural sway and respiration were simultaneously recorded with a force plate and respiratory belt under eyes-open and eyes-closed conditions. Posturo-respiratory synchronization was determined by quantifying the variation of the phase relationship between the dominant oscillatory mode of respiration and corresponding oscillations within postural sway. Groups were similar in age, gender distribution, height, body mass, and intervention compliance. Neither intervention altered average sway speed, sway magnitude or respiratory rate. As compared to the education-control group, however, Tai Chi training reduced posturo-respiratory synchronization when standing with eyes open or closed (ppostural control or respiration, yet reduced the coupling between respiration and postural control. The beneficial effects of Tai Chi training may therefore stem in part from optimization of this multi-system interaction.

  15. Small ecosystem engineers as important regulators of lake's sediment respiration.

    Science.gov (United States)

    Baranov, Victor; Lewandowski, Joerg; Krause, Stefan; Romeijn, Paul

    2016-04-01

    Although shallow lakes are covering only about 1.5% of the land surface of the Earth, they are responsible for sequestration of carbon amounts similar or even larger than those sequestered in all marine sediments. One of the most important drivers of the carbon sequestration in lakes is sediment respiration. Especially in shallow lakes, bioturbation, i.e. the biogenic reworking of the sediment matrix and the transport of fluids within the sediment, severely impacts on sediment respiration. Widespread freshwater bioturbators such as chironomid larvae (Diptera, Chironomidae) are building tubes in the sediment and actively pump water through their burrows (ventilation). In the present work we study how different organism densities and temperatures (5-30°C) impact on respiration rates. In a microcosm experiment the bioreactive resazurin/resorufin smart tracer system was applied for quantifying the impacts of different densities of Chironomidae (Diptera) larvae (0, 1000, 2000 larvae/m2) on sediment respiration. Tracer transformation rates (and sediment respiration) were correlated with larval densities with highest transformation rates occurring in microcosms with highest larval densities. Respiration differences between defaunated sediment and sediment with 1000 and 2000 larvae per m2 was insignificant at 5 °C, and was progressively increasing with rising temperatures. At 30 °C respiration rates of sediment with 2000 larvae per m2 was 4.8 times higher than those of defaunated sediment. We interpret this as an effect of temperature on larval metabolic and locomotory activity. Furthermore, bacterial communities are benefiting from the combination of the high water temperatures and bioirrigation as bacterial community are able to maintain high metabolic rates due to oxygen supplied by bioirrigation. In the context of global climate change that means that chironomid ecosystem engineering activity will have a profound and increasing impact on lake sediment respiration

  16. Respirable dust meter locates super polluters in traffic

    OpenAIRE

    Schrauwers, A.

    2006-01-01

    The Netherlands is having trouble with the EU standards for respirable dust (PM 10). The Dutch Council of State recently blocked a number of residential development projects because local conditions failed to meet the PM 10 standard. Research by the Nano Structured Materials group at TU Delft shows that some 5% of the seven or so million motor vehicles currently on the road in the Netherlands are responsible for over 40% of all respirable dust emitted by traffic. Although most of these super ...

  17. Temperature-mediated changes in microbial carbon use efficiency and 13C discrimination

    Science.gov (United States)

    Lehmeier, Christoph A.; Ballantyne, Ford, IV; Min, Kyungjin; Billings, Sharon A.

    2016-06-01

    Understanding how carbon dioxide (CO2) flux from ecosystems feeds back to climate warming depends in part on our ability to quantify the efficiency with which microorganisms convert organic carbon (C) into either biomass or CO2. Quantifying ecosystem-level respiratory CO2 losses often also requires assumptions about stable C isotope fractionations associated with the microbial transformation of organic substrates. However, the diversity of organic substrates' δ13C and the challenges of measuring microbial C use efficiency (CUE) in their natural environment fundamentally limit our ability to project ecosystem C budgets in a warming climate. Here, we quantify the effect of temperature on C fluxes during metabolic transformations of cellobiose, a common microbial substrate, by a cosmopolitan microorganism growing at a constant rate. Biomass C specific respiration rate increased by 250 % between 13 and 26.5 °C, decreasing CUE from 77 to 56 %. Biomass C specific respiration rate was positively correlated with an increase in respiratory 13C discrimination from 4.4 to 6.7 ‰ across the same temperature range. This first demonstration of a direct link between temperature, microbial CUE, and associated isotope fluxes provides a critical step towards understanding δ13C of respired CO2 at multiple scales, and towards a framework for predicting future ecosystem C fluxes.

  18. Soil microbial response to photo-degraded C60 fullerenes.

    Science.gov (United States)

    Berry, Timothy D; Clavijo, Andrea P; Zhao, Yingcan; Jafvert, Chad T; Turco, Ronald F; Filley, Timothy R

    2016-04-01

    Recent studies indicate that while unfunctionalized carbon nanomaterials (CNMs) exhibit very low decomposition rates in soils, even minor surface functionalization (e.g., as a result of photochemical weathering) may accelerate microbial decay. We present results from a C60 fullerene-soil incubation study designed to investigate the potential links between photochemical and microbial degradation of photo-irradiated C60. Irradiating aqueous (13)C-labeled C60 with solar-wavelength light resulted in a complex mixture of intermediate products with decreased aromaticity. Although addition of irradiated C60 to soil microcosms had little effect on net soil respiration, excess (13)C in the respired CO2 demonstrates that photo-irradiating C60 enhanced its degradation in soil, with ∼ 0.78% of 60 day photo-irradiated C60 mineralized. Community analysis by DGGE found that soil microbial community structure was altered and depended on the photo-treatment duration. These findings demonstrate how abiotic and biotic transformation processes can couple to influence degradation of CNMs in the natural environment.

  19. Microbial activity of soil cultivated with corn in association with weeds under different fertility management systems

    Directory of Open Access Journals (Sweden)

    Christiane Melo

    2014-12-01

    Full Text Available Interactions between weeds and soil microorganisms can give them a competitive advantage over crops. This study assessed the biomass and microbial activity of soil cultivated with weeds and corn (Zea mays L. in monoculture and in competition under different fertility management systems. The experiment considered four soil fertility management systems (calcium and magnesium silicate + fertilization; limestone + fertilization; no correction source + fertilization; no correction source + no fertilization and 12 crops (five competition arrangements between corn and weeds Urochloa brizantha (Hochst. ex A. Rich. R.D. Webster, lpomoea grandifolia (Dammer O'Donell, Conyza canadensis (L. Cronquist, Hyptis suaveolens (L. Poit., and Bidens pilosa L. plus the six species in monoculture and bare soil. After 60 d coexisting in a greenhouse, soil samples were collected to determine microbial biomass, respiration rate, and metabolic quotient. Soils cultivated with B. pilosa and Z. mays+U. brizantha showed higher microbial biomass. Cultivation of B. pilosa and Z. mays+H. suaveolens provided greater energy efficiency to maintain microbial cells. Biomass and microbial activity were altered by plant species, coexistence, and soil fertility management. Calcium and magnesium silicate, as well as limestone similarly influenced biomass and respiration rate of soil cultivated with most species. For some crops, the Si source was better than limestone to promote lower specific activity of the edaphic microbiota. The change in the microbial activity of soil can be a strategy used by the species to minimize the effects of competition.

  20. Two Proximal Skin Electrodes — A Respiration Rate Body Sensor

    Directory of Open Access Journals (Sweden)

    Viktor Avbelj

    2012-10-01

    Full Text Available We propose a new body sensor for extracting the respiration rate based on the amplitude changes in the body surface potential differences between two proximal body electrodes. The sensor could be designed as a plaster-like reusable unit that can be easily fixed onto the surface of the body. It could be equipped either with a sufficiently large memory for storing the measured data or with a low-power radio system that can transmit the measured data to a gateway for further processing. We explore the influence of the sensor’s position on the quality of the extracted results using multi-channel ECG measurements and considering all the pairs of two neighboring electrodes as potential respiration-rate sensors. The analysis of the clinical measurements, which also include reference thermistor-based respiration signals, shows that the proposed approach is a viable option for monitoring the respiration frequency and for a rough classification of breathing types. The obtained results were evaluated on a wireless prototype of a respiration body sensor. We indicate the best positions for the respiration body sensor and prove that a single sensor for body surface potential difference on proximal skin electrodes can be used for combined measurements of respiratory and cardiac activities.

  1. Respiration during Postharvest Development of Soursop Fruit, Annona muricata L.

    Science.gov (United States)

    Bruinsma, J; Paull, R E

    1984-09-01

    Fruit of soursop, Annona muricata L., showed increased CO(2) production 2 days after harvest, preceding the respiratory increase that coincided with autocatalytic ethylene evolution and other ripening phenomena. Experiments to alter gas exchange patterns of postharvest fruit parts and tissue cylinders had little success.The respiratory quotient of tissue discs was near unity throughout development. 2,4-Dinitrophenol uncoupled respiration more effectively than carbonylcyanide m-chlorophenylhydrazone; 0.4 millimolar KCN stimulated, 4 millimolar salicylhydroxamic acid slightly inhibited, and their combination strongly inhibited respiration, as did 10 millimolar NaN(3). Tricarboxylic acid cycle members and ascorbate were more effective substrates than sugars, but acetate and glutarate strongly inhibited.Disc respiration showed the same early peak as whole fruit respiration; this peak is thus an inherent characteristic of postharvest development and cannot be ascribed to differences between ovaries of the aggregatetype fruit. The capacity of the respiratory apparatus did not change during this preclimacteric peak, but the contents of rate-limiting malate and citrate increased after harvest.It is concluded that the preclimacteric rise in CO(2) evolution reflects increased mitochondrial respiration because of enhanced supply of carboxylates as a substrate, probably induced by detachment from the tree. The second rise corresponds with the respiration during ripening of other climacteric fruits.

  2. Effects of agriculture on wood breakdown and microbial biofilm respiration in southern Appalachian streams

    Science.gov (United States)

    E.F Benfield McTammany; J.R. Webster

    2008-01-01

    Agriculture causes high sediment, nutrient and light input to streams, which may affect rates of ecosystem processes, such as organic matter decay. In the southern Appalachians, socioeconomic trends over the past 50 years have caused widespread abandonment of farmland with subsequent reforestation. Physical and chemical properties of streams in these reforested areas...

  3. 42 CFR 84.254 - Powered air-purifying respirators; requirements and tests.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Powered air-purifying respirators; requirements and... DEVICES Special Use Respirators § 84.254 Powered air-purifying respirators; requirements and tests. (a... air-purifying respirators prescribed in subpart L of this part are applicable to vinyl...

  4. 42 CFR 84.1147 - Silica mist test for dust, fume, and mist respirators; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... respirators; minimum requirements. 84.1147 Section 84.1147 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF... Efficiency Respirators and Combination Gas Masks § 84.1147 Silica mist test for dust, fume, and mist respirators; minimum requirements. (a) Three non-powered respirators will be tested for a period of...

  5. 42 CFR 84.50 - Types of respirators to be approved; scope of approval.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Types of respirators to be approved; scope of... Classification of Approved Respirators; Scope of Approval; Atmospheric Hazards; Service Time § 84.50 Types of respirators to be approved; scope of approval. Approvals shall be issued for the types of respirators...

  6. 42 CFR 84.1146 - Lead fume test for dust, fume, and mist respirators; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Lead fume test for dust, fume, and mist respirators... Efficiency Respirators and Combination Gas Masks § 84.1146 Lead fume test for dust, fume, and mist respirators; minimum requirements. (a) Three non-powered respirators will be tested for a period of...

  7. 42 CFR 84.170 - Non-powered air-purifying particulate respirators; description.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Non-powered air-purifying particulate respirators... DEVICES Non-Powered Air-Purifying Particulate Respirators § 84.170 Non-powered air-purifying particulate respirators; description. (a) Non-powered air-purifying particulate respirators utilize the wearer's...

  8. 42 CFR 84.131 - Supplied-air respirators; required components.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Supplied-air respirators; required components. 84... Supplied-Air Respirators § 84.131 Supplied-air respirators; required components. (a) Each supplied-air respirator described in § 84.130 shall, where its design requires, contain the following component parts:...

  9. 42 CFR 84.1140 - Dust, fume, and mist respirators; performance requirements; general.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Dust, fume, and mist respirators; performance... Respirators and Combination Gas Masks § 84.1140 Dust, fume, and mist respirators; performance requirements; general. Dust, fume, and mist respirators and the individual components of each such device shall,...

  10. 42 CFR 84.179 - Non-powered air-purifying particulate respirators; filter identification.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Non-powered air-purifying particulate respirators... RESPIRATORY PROTECTIVE DEVICES Non-Powered Air-Purifying Particulate Respirators § 84.179 Non-powered air-purifying particulate respirators; filter identification. (a) The respirator manufacturer, as part of...

  11. 42 CFR 84.147 - Type B supplied-air respirator; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Type B supplied-air respirator; minimum... DEVICES Supplied-Air Respirators § 84.147 Type B supplied-air respirator; minimum requirements. No Type B supplied-air respirator shall be approved for use with a blower or with connection to an air supply...

  12. 42 CFR 84.253 - Chemical-cartridge respirators; requirements and tests.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Chemical-cartridge respirators; requirements and... DEVICES Special Use Respirators § 84.253 Chemical-cartridge respirators; requirements and tests. (a... for chemical-cartridge respirators prescribed in Subpart L of this part are applicable to...

  13. 42 CFR 84.206 - Particulate tests; respirators with filters; minimum requirements; general.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Particulate tests; respirators with filters... RESPIRATORY PROTECTIVE DEVICES Chemical Cartridge Respirators § 84.206 Particulate tests; respirators with filters; minimum requirements; general. (a) Three respirators with cartridges containing, or...

  14. 42 CFR 84.139 - Head and neck protection; supplied-air respirators; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Head and neck protection; supplied-air respirators... PROTECTIVE DEVICES Supplied-Air Respirators § 84.139 Head and neck protection; supplied-air respirators; minimum requirements. Type AE, BE, and CE supplied-air respirators shall be designed and constructed...

  15. 42 CFR 84.1158 - Dust, fume, and mist tests; respirators with filters; minimum requirements; general.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Dust, fume, and mist tests; respirators with...-Purifying High Efficiency Respirators and Combination Gas Masks § 84.1158 Dust, fume, and mist tests; respirators with filters; minimum requirements; general. (a) Three respirators with cartridges containing,...

  16. 42 CFR 84.148 - Type C supplied-air respirator, continuous flow class; minimum requirements.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Type C supplied-air respirator, continuous flow... RESPIRATORY PROTECTIVE DEVICES Supplied-Air Respirators § 84.148 Type C supplied-air respirator, continuous flow class; minimum requirements. (a) Respirators tested under this section shall be approved only...

  17. A global database of soil respiration data

    Science.gov (United States)

    Bond-Lamberty, B.; Thomson, A.

    2010-06-01

    Soil respiration - RS, the flux of CO2 from the soil to the atmosphere - is probably the least well constrained component of the terrestrial carbon cycle. Here we introduce the SRDB database, a near-universal compendium of published RS data, and make it available to the scientific community both as a traditional static archive and as a dynamic community database that may be updated over time by interested users. The database encompasses all published studies that report one of the following data measured in the field (not laboratory): annual RS, mean seasonal RS, a seasonal or annual partitioning of RS into its sources fluxes, RS temperature response (Q10), or RS at 10 °C. Its orientation is thus to seasonal and annual fluxes, not shorter-term or chamber-specific measurements. To date, data from 818 studies have been entered into the database, constituting 3379 records. The data span the measurement years 1961-2007 and are dominated by temperate, well-drained forests. We briefly examine some aspects of the SRDB data - its climate space coverage, mean annual RS fluxes and their correlation with other carbon fluxes, RS variability, temperature sensitivities, and the partitioning of RS source flux - and suggest some potential lines of research that could be explored using these data. The SRDB database is available online in a permanent archive as well as via a project-hosting repository; the latter source leverages open-source software technologies to encourage wider participation in the database's future development. Ultimately, we hope that the updating of, and corrections to, the SRDB will become a shared project, managed by the users of these data in the scientific community.

  18. Surfactants and the Mechanics of Respiration

    Science.gov (United States)

    Jbaily, Abdulrahman; Szeri, Andrew J.

    2016-11-01

    Alveoli are small sacs found at the end of terminal bronchioles in human lungs with a mean diameter of 200 μm. A thin layer of fluid (hypophase) coats the inner face of an alveolus and is in contact with the air in the lungs. The thickness of this layer varies among alveoli, but is in the range of 0.1 to 0.5 μm for many portions of the alveolar network. The interfacial tension σ at the air-hypophase interface tends to favor collapse of the alveolus, and resists its expansion during inhalation. Type II alveolar cells synthesize and secrete a mixture of phospholipids and proteins called pulmonary surfactant. These surfactant molecules adsorb to the interface causing σ of water at body temperature is 70 mN/m and falls to an equilibrium value of 25 mN/m when surfactants are present. Also, in a dynamic sense, it is known that σ is reduced to near 0 during exhalation when the surfactant film compresses. In this work, the authors develop a mechanical and transport model of the alveolus to study the effect of surfactants on various aspects of respiration. The model is composed of three principal parts: (i) air movement into and out of the alveolus; (ii) a balance of linear momentum across the two-layered membrane of the alveolus (hypophase and elastic wall); and (iii) a pulmonary surfactant transport problem in the hypophase. The goal is to evaluate the influence of pulmonary surfactant on respiratory mechanics.

  19. Utilization of subsurface microbial electrochemical systems to elucidate the mechanisms of competition between methanogenesis and microbial iron(III)/humic acid reduction in Arctic peat soils

    Science.gov (United States)

    Friedman, E. S.; Miller, K.; Lipson, D.; Angenent, L. T.

    2012-12-01

    High-latitude peat soils are a major carbon reservoir, and there is growing concern that previously dormant carbon from this reservoir could be released to the atmosphere as a result of continued climate change. Microbial processes, such as methanogenesis and carbon dioxide production via iron(III) or humic acid reduction, are at the heart of the carbon cycle in Arctic peat soils [1]. A deeper understanding of the factors governing microbial dominance in these soils is crucial for predicting the effects of continued climate change. In previous years, we have demonstrated the viability of a potentiostatically-controlled subsurface microbial electrochemical system-based biosensor that measures microbial respiration via exocellular electron transfer [2]. This system utilizes a graphite working electrode poised at 0.1 V NHE to mimic ferric iron and humic acid compounds. Microbes that would normally utilize these compounds as electron acceptors donate electrons to the electrode instead. The resulting current is a measure of microbial respiration with the electrode and is recorded with respect to time. Here, we examine the mechanistic relationship between methanogenesis and iron(III)- or humic acid-reduction by using these same microbial-three electrode systems to provide an inexhaustible source of alternate electron acceptor to microbes in these soils. Chamber-based carbon dioxide and methane fluxes were measured from soil collars with and without microbial three-electrode systems over a period of four weeks. In addition, in some collars we simulated increased fermentation by applying acetate treatments to understand possible effects of continued climate change on microbial processes in these carbon-rich soils. The results from this work aim to increase our fundamental understanding of competition between electron acceptors, and will provide valuable data for climate modeling scenarios. 1. Lipson, D.A., et al., Reduction of iron (III) and humic substances plays a major

  20. Using 13C-labeled benzene and Raman gas spectroscopy to investigate respiration and biodegradation kinetics following soil contamination

    Science.gov (United States)

    Jochum, Tobias; Popp, Juergen; Frosch, Torsten

    2016-04-01

    Soil and groundwater contamination with benzene can cause serious environmental damages. However, many soil microorganisms are capable to adapt and known to strongly control the fate of organic contamination. Cavity enhanced Raman gas spectroscopy (CERS) was applied to investigate the short-term response of indigenous soil bacteria to a sudden surface contamination with benzene regarding the temporal variations of gas products and their exchange rates with the adjacent atmosphere. 13C-labeled benzene was spiked on a silty-loamy soil column (sampled from Hainich National Park, Germany) in order to track and separate the changes in heterotrophic soil respiration - involving 12CO2 and O2 - from the microbial process of benzene degradation, which ultimately forms 13CO2.1 The respiratory quotient (RQ) of 0.98 decreased significantly after the spiking and increased again within 33 hours to a value of 0.72. This coincided with maximum 13CO2 concentration rates (0.63 μ mol m-2 s-1), indicating highest benzene degradation at 33 hours after the spiking event. The diffusion of benzene in the headspace and the biodegradation into 13CO2 were simultaneously monitored and 12 days after the benzene spiking no measurable degradation was detected anymore.1 The RQ finally returned to a value of 0.96 demonstrating the reestablished aerobic respiration. In summary, this study shows the potential of combining Raman gas spectroscopy and stable isotopes to follow soil microbial biodegradation dynamics while simultaneously monitoring the underlying respiration behavior. Support by the Collaborative Research Center 1076 Aqua Diva is kindly acknowledged. We thank Beate Michalzik for soil analysis and discussion. 1. T. Jochum, B. Michalzik, A. Bachmann, J. Popp and T. Frosch, Analyst, 2015, 140, 3143-3149.

  1. [Factors influencing the spatial variability in soil respiration under different land use regimes].

    Science.gov (United States)

    Chen, Shu-Tao; Liu, Qiao-Hui; Hu, Zheng-Hua; Liu, Yan; Ren, Jing-Quan; Xie, Wei

    2013-03-01

    In order to investigate the factors influencing the spatial variability in soil respiration under different land use regimes, field experiments were performed. Soil respiration and relevant environment, vegetation and soil factors were measured. The spatial variability in soil respiration and the relationship between soil respiration and these measured factors were investigated. Results indicated that land use regimes had significant effects on soil respiration. Soil respiration varied significantly (P DBH) of trees can be explained by a natural logarithmic function. A model composed of soil organic carbon (C, %), available phosphorous (AP, g x kg(-1)) and diameter at breast height (DBH, cm) explained 92.8% spatial variability in soil respiration for forest ecosystems.

  2. Microbial growth and carbon use efficiency in the rhizosphere and root-free soil.

    Science.gov (United States)

    Blagodatskaya, Evgenia; Blagodatsky, Sergey; Anderson, Traute-Heidi; Kuzyakov, Yakov

    2014-01-01

    Plant-microbial interactions alter C and N balance in the rhizosphere and affect the microbial carbon use efficiency (CUE)-the fundamental characteristic of microbial metabolism. Estimation of CUE in microbial hotspots with high dynamics of activity and changes of microbial physiological state from dormancy to activity is a challenge in soil microbiology. We analyzed respiratory activity, microbial DNA content and CUE by manipulation the C and nutrients availability in the soil under Beta vulgaris. All measurements were done in root-free and rhizosphere soil under steady-state conditions and during microbial growth induced by addition of glucose. Microorganisms in the rhizosphere and root-free soil differed in their CUE dynamics due to varying time delays between respiration burst and DNA increase. Constant CUE in an exponentially-growing microbial community in rhizosphere demonstrated the balanced growth. In contrast, the CUE in the root-free soil increased more than three times at the end of exponential growth and was 1.5 times higher than in the rhizosphere. Plants alter the dynamics of microbial CUE by balancing the catabolic and anabolic processes, which were decoupled in the root-free soil. The effects of N and C availability on CUE in rhizosphere and root-free soil are discussed.

  3. Microbial growth and carbon use efficiency in the rhizosphere and root-free soil.

    Directory of Open Access Journals (Sweden)

    Evgenia Blagodatskaya

    Full Text Available Plant-microbial interactions alter C and N balance in the rhizosphere and affect the microbial carbon use efficiency (CUE-the fundamental characteristic of microbial metabolism. Estimation of CUE in microbial hotspots with high dynamics of activity and changes of microbial physiological state from dormancy to activity is a challenge in soil microbiology. We analyzed respiratory activity, microbial DNA content and CUE by manipulation the C and nutrients availability in the soil under Beta vulgaris. All measurements were done in root-free and rhizosphere soil under steady-state conditions and during microbial growth induced by addition of glucose. Microorganisms in the rhizosphere and root-free soil differed in their CUE dynamics due to varying time delays between respiration burst and DNA increase. Constant CUE in an exponentially-growing microbial community in rhizosphere demonstrated the balanced growth. In contrast, the CUE in the root-free soil increased more than three times at the end of exponential growth and was 1.5 times higher than in the rhizosphere. Plants alter the dynamics of microbial CUE by balancing the catabolic and anabolic processes, which were decoupled in the root-free soil. The effects of N and C availability on CUE in rhizosphere and root-free soil are discussed.

  4. Experimental Air Warming of a Stylosanthes capitata, Vogel Dominated Tropical Pasture Affects Soil Respiration and Nitrogen Dynamics

    Science.gov (United States)

    Gonzalez-Meler, Miquel A.; Silva, Lais B. C.; Dias-De-Oliveira, Eduardo; Flower, Charles E.; Martinez, Carlos A.

    2017-01-01

    Warming due to global climate change is predicted to reach 2°C in tropical latitudes. There is an alarming paucity of information regarding the effects of air temperature on tropical agroecosystems, including foraging pastures. Here, we investigated the effects of a 2°C increase in air temperature over ambient for 30 days on an established tropical pasture (Ribeirão Preto, São Paulo, Brazil) dominated by the legume Stylosanthes capitata Vogel, using a T-FACE (temperature free-air controlled enhancement) system. We tested the effects of air warming on soil properties [carbon (C), nitrogen (N), and their stable isotopic levels (δ13C and δ15N), as well as soil respiration and soil enzymatic activity] and aboveground characteristics (foliar C, N, δ13C, δ15N, leaf area index, and aboveground biomass) under field conditions. Results show that experimental air warming moderately increased soil respiration rates compared to ambient temperature. Soil respiration was positively correlated with soil temperature and moisture during mid-day (when soil respiration was at its highest) but not at dusk. Foliar δ13C were not different between control and elevated temperature treatments, indicating that plants grown in warmed plots did not show the obvious signs of water stress often seen in warming experiments. The 15N isotopic composition of leaves from plants grown at elevated temperature was lower than in ambient plants, suggesting perhaps a higher proportion of N-fixation contributing to tissue N in warmed plants when compared to ambient ones. Soil microbial enzymatic activity decreased in response to the air warming treatment, suggesting a slower decomposition of organic matter under elevated air temperature conditions. Decreased soil enzyme capacity and increases in soil respiration and plant biomass in plots exposed to high temperature suggest that increased root activity may have caused the increase seen in soil respiration in this tropical pasture. This response

  5. Respirator studies for the ERDA Division of Safety, Standards, and Compliance, July 1, 1975--June 30, 1976. [Physiological effects of wearing respirators

    Energy Technology Data Exchange (ETDEWEB)

    Davis, T.O.; Raven, P.B.; Shafer, C.L.; Linnebur, A.C.; Bustos, J.M.; Wheat, L.D.; Douglas, D.D.

    1977-03-01

    Results of a study to determine what effect wearing a respirator has on worker performance, and which physiological parameters an industrial physician should consider when examining an employee who will be wearing a respirator while working are presented. (TFD)

  6. Students' communicative competence

    Directory of Open Access Journals (Sweden)

    Šafranj Jelisaveta

    2009-01-01

    Full Text Available Communicative competence is the ability to send messages which promote attainment of goals while maintaining social acceptability. Competent communicators attempt to align themselves with each others goals and methods to produce a smooth, productive and often enjoyable dialogue. The aim of this research was to investigate self-perceived communicative competence (SPCC of students of Engineering Management in General English and English for Specific Purposes (ESP. A longitudinal study was carried out starting with the first year students at the Faculty of Technical Sciences in Novi Sad and was repeated with the same sample of students during their second and third year of study. Participation was voluntary and took place during regular class time. The measure of communicative competence employed was the Self-perceived Communication Competence Scale. The results of the study indicated that differences in SPCC between the years do exist. The SPCC gradually improved between the first, the second and the third year. The research was also motivated by gaining better overview of the teaching activity. An anonymous questionnaire provided many useful hints and ideas for further work and thus, language teacher made a thorough analysis of the overall teaching procedure. However, it is essential to get some feedback and talk to students in order to evaluate both them and ourselves as well as the teaching syllabus.

  7. Acquiring specific interpreting competence

    Directory of Open Access Journals (Sweden)

    Jana Zidar Forte

    2012-12-01

    Full Text Available In postgraduate interpreter training, the main objective of the course is to help trainees develop various competences, from linguistic, textual and cultural competence, to professional and specific interpreting competence. For simultaneous interpreting (SI, the main focus is on mastering the SI technique and strategies as well as on developing and strengthening communicative skills, which is discussed and illustrated with examples in the present paper. First, a brief overview is given of all the necessary competences of a professional interpreter with greater emphasis on specific interpreting competence for SI. In the second part of the paper, various approaches are described in terms of acquiring specific skills and strategies, specifically through a range of exercises. Besides interpreting entire speeches, practical courses should also consist of targeted exercises, which help trainees develop suitable coping strategies and mechanisms (later on almost automatisms, while at the same time "force" them to reflect on their individual learning process and interpreting performance. This provides a solid base on which trained interpreters can progress and develop their skills also after joining the professional sphere.

  8. Substrate and nutrient limitation regulating microbial growth in soil

    Science.gov (United States)

    Bååth, Erland

    2015-04-01

    Microbial activity and growth in soil is regulated by several abiotic factors, including temperature, moisture and pH as the most important ones. At the same time nutrient conditions and substrate availability will also determine microbial growth. Amount of substrate will not only affect overall microbial growth, but also affect the balance of fungal and bacterial growth. The type of substrate will also affect the latter. Furthermore, according to Liebig law of limiting factors, we would expect one nutrient to be the main limiting one for microbial growth in soil. When this nutrient is added, the initial second liming factor will become the main one, adding complexity to the microbial response after adding different substrates. I will initially describe different ways of determining limiting factors for bacterial growth in soil, especially a rapid method estimating bacterial growth, using the leucine incorporation technique, after adding C (as glucose), N (as ammonium nitrate) and P (as phosphate). Scenarios of different limitations will be covered, with the bacterial growth response compared with fungal growth and total activity (respiration). The "degree of limitation", as well as the main limiting nutrient, can be altered by adding substrate of different stoichiometric composition. However, the organism group responding after alleviating the nutrient limitation can differ depending on the type of substrate added. There will also be situations, where fungi and bacteria appear to be limited by different nutrients. Finally, I will describe interactions between abiotic factors and the response of the soil microbiota to alleviation of limiting factors.

  9. Seasonality of temperate forest photosynthesis and daytime respiration

    Science.gov (United States)

    Wehr, R.; Munger, J. W.; McManus, J. B.; Nelson, D. D.; Zahniser, M. S.; Davidson, E. A.; Wofsy, S. C.; Saleska, S. R.

    2016-06-01

    Terrestrial ecosystems currently offset one-quarter of anthropogenic carbon dioxide (CO2) emissions because of a slight imbalance between global terrestrial photosynthesis and respiration. Understanding what controls these two biological fluxes is therefore crucial to predicting climate change. Yet there is no way of directly measuring the photosynthesis or daytime respiration of a whole ecosystem of interacting organisms; instead, these fluxes are generally inferred from measurements of net ecosystem-atmosphere CO2 exchange (NEE), in a way that is based on assumed ecosystem-scale responses to the environment. The consequent view of temperate deciduous forests (an important CO2 sink) is that, first, ecosystem respiration is greater during the day than at night; and second, ecosystem photosynthetic light-use efficiency peaks after leaf expansion in spring and then declines, presumably because of leaf ageing or water stress. This view has underlain the development of terrestrial biosphere models used in climate prediction and of remote sensing indices of global biosphere productivity. Here, we use new isotopic instrumentation to determine ecosystem photosynthesis and daytime respiration in a temperate deciduous forest over a three-year period. We find that ecosystem respiration is lower during the day than at night—the first robust evidence of the inhibition of leaf respiration by light at the ecosystem scale. Because they do not capture this effect, standard approaches overestimate ecosystem photosynthesis and daytime respiration in the first half of the growing season at our site, and inaccurately portray ecosystem photosynthetic light-use efficiency. These findings revise our understanding of forest-atmosphere carbon exchange, and provide a basis for investigating how leaf-level physiological dynamics manifest at the canopy scale in other ecosystems.

  10. Seasonality of temperate forest photosynthesis and daytime respiration.

    Science.gov (United States)

    Wehr, R; Munger, J W; McManus, J B; Nelson, D D; Zahniser, M S; Davidson, E A; Wofsy, S C; Saleska, S R

    2016-06-30

    Terrestrial ecosystems currently offset one-quarter of anthropogenic carbon dioxide (CO2) emissions because of a slight imbalance between global terrestrial photosynthesis and respiration. Understanding what controls these two biological fluxes is therefore crucial to predicting climate change. Yet there is no way of directly measuring the photosynthesis or daytime respiration of a whole ecosystem of interacting organisms; instead, these fluxes are generally inferred from measurements of net ecosystem-atmosphere CO2 exchange (NEE), in a way that is based on assumed ecosystem-scale responses to the environment. The consequent view of temperate deciduous forests (an important CO2 sink) is that, first, ecosystem respiration is greater during the day than at night; and second, ecosystem photosynthetic light-use efficiency peaks after leaf expansion in spring and then declines, presumably because of leaf ageing or water stress. This view has underlain the development of terrestrial biosphere models used in climate prediction and of remote sensing indices of global biosphere productivity. Here, we use new isotopic instrumentation to determine ecosystem photosynthesis and daytime respiration in a temperate deciduous forest over a three-year period. We find that ecosystem respiration is lower during the day than at night-the first robust evidence of the inhibition of leaf respiration by light at the ecosystem scale. Because they do not capture this effect, standard approaches overestimate ecosystem photosynthesis and daytime respiration in the first half of the growing season at our site, and inaccurately portray ecosystem photosynthetic light-use efficiency. These findings revise our understanding of forest-atmosphere carbon exchange, and provide a basis for investigating how leaf-level physiological dynamics manifest at the canopy scale in other ecosystems.

  11. Fit testing respirators for public health medical emergencies.

    Science.gov (United States)

    Brosseau, Lisa M

    2010-11-01

    Concerns about limiting pandemic infectious disease transmission when vaccines are not yet available prompted the Food and Drug Administration (FDA) to develop guidance for marketing respirators for use in public health medical emergencies. This project describes the results of filtering facepiece fit tests using 35 untrained, inexperienced subjects meeting the face size criteria of the National Institute for Occupational Safety and Health bivariate panel, in preparation for an FDA 510(k) application. Quantitative fit factors were measured for each subject on two replicates of each of two N95 filtering facepiece respirators (A and B) using the TSI Portacount Plus with N95 Companion. Subjects received no training or assistance with donning and had no prior experience with wearing respirators. The panel consisted of 20 females and 15 males; 80% were between 18 and 34 years of age. Almost all subjects properly placed the respirator on the face and formed the nose clip. Straps were improperly placed 25% of the time. Users reviewed the donning instructions 73% of the time and performed a seal check 80% of the time. Leaks were observed during 80% of the fit tests, most frequently at the chin during the head up and down exercise. For Respirator A, all but one subject had a 95% fit factor greater than 2 (the minimum required by FDA); one subject had a 95% fit factor of 1.5. All subjects had a 95% fit factor greater than 2.5 for Respirator B. Geometric mean fit factors ranged from 19-28 for these two respirators, and a majority of subjects were able to achieve a fit factor of 10 most of the time. However, fewer than 25% of subjects received the fit factor of 100 expected in workplace settings.

  12. A global database of soil respiration data

    Directory of Open Access Journals (Sweden)

    B. Bond-Lamberty

    2010-06-01

    Full Text Available Soil respirationRS, the flux of CO2 from the soil to the atmosphere – is probably the least well constrained component of the terrestrial carbon cycle. Here we introduce the SRDB database, a near-universal compendium of published RS data, and make it available to the scientific community both as a traditional static archive and as a dynamic community database that may be updated over time by interested users. The database encompasses all published studies that report one of the following data measured in the field (not laboratory: annual RS, mean seasonal RS, a seasonal or annual partitioning of RS into its sources fluxes, RS temperature response (Q10, or RS at 10 °C. Its orientation is thus to seasonal and annual fluxes, not shorter-term or chamber-specific measurements. To date, data from 818 studies have been entered into the database, constituting 3379 records. The data span the measurement years 1961–2007 and are dominated by temperate, well-drained forests. We briefly examine some aspects of the SRDB data – its climate space coverage, mean annual RS fluxes and their correlation with other carbon fluxes, RS variability, temperature sensitivities, and the partitioning of RS source flux – and suggest some potential lines of research that could be explored using these data. The SRDB database is available online in a permanent archive as well as via a project-hosting repository; the latter source leverages open-source software technologies to encourage wider participation in the database's future development. Ultimately, we hope that the updating of, and corrections to, the SRDB will become a shared project, managed by the users of these data in the scientific community.

  13. A global database of soil respiration data

    Directory of Open Access Journals (Sweden)

    B. Bond-Lamberty

    2010-02-01

    Full Text Available Soil respirationRS, the flux of autotropically- and heterotrophically-generated CO2 from the soil to the atmosphere – remains the least well-constrained component of the terrestrial C cycle. Here we introduce the SRDB database, a near-universal compendium of published RS data, and make it available to the scientific community both as a traditional static archive and as a dynamic community database that will be updated over time by interested users. The database encompasses all published studies that report one of the following data measured in the field (not laboratory: annual RS, mean seasonal RS, a seasonal or annual partitioning of RS into its sources fluxes, RS temperature response (Q10, or RS at 10 °C. Its orientation is thus to seasonal and annual fluxes, not shorter-term or chamber-specific measurements. To date, data from 818 studies have been entered into the database, constituting 3379 records. The data span the measurement years 1961–2007 and are dominated by temperate, well-drained forests. We briefly examine some aspects of the SRDB data – mean annual RS fluxes and their correlation with other carbon fluxes, RS variability, temperature sensitivities, and the partitioning of RS source flux – and suggest some potential lines of research that could be explored using these data. The SRDB database described here is available online in a permanent archive as well as via a project-hosting repository; the latter source leverages open-source software technologies to encourage wider participation in the database's future development. Ultimately, we hope that the updating of, and corrections to, the SRDB will become a shared project, managed by the users of these data in the scientific community.

  14. Pyrogenic effect of respirable road dust particles

    Energy Technology Data Exchange (ETDEWEB)

    Jayawardena, Umesh; Tollemark, Linda; Tagesson, Christer; Leanderson, Per, E-mail: per.leanderson@lio.s [Occupational and Environmental Medicine, University Hospital, S-581 85 Linkoeping (Sweden)

    2009-02-01

    Because pyrogenic (fever-inducing) compounds on ambient particles may play an important role for particle toxicity, simple methods to measure pyrogens on particles are needed. Here we have used a modified in vitro pyrogen test (IPT) to study the release of interleukin 1beta (IL-1beta) in whole human blood exposed to respirable road-dust particles (RRDP). Road dusts were collected from the roadside at six different streets in three Swedish cities and particles with a diameter less than 10 mum (RRDP) were prepared by a water sedimentation procedure followed by lyophilisation. RRDP (200 mul of 1 - 10{sup 6} ng/ml) were mixed with 50 mul whole blood and incubated at 37 deg. C overnight before IL-1beta was analysed with chemiluminescence ELISA in 384-well plates. Endotoxin (lipopolysaccharide from Salmonella minnesota), zymosan B and Curdlan (P-1,3-glucan) were used as positive controls. All RRDP samples had a pyrogenic effect and the most active sample produced 1.6 times more IL-1beta than the least active. This formation was of the same magnitude as in samples with 10 ng LPS/ml and was larger than that evoked by zymosan B and Curdlan (by mass basis). The method was sensitive enough to determine formation of IL-1beta in mixtures with 10 ng RRDP/ml or 0.01 ng LPS/ml. The endotoxin inhibitor, polymyxin B (10 mug/ml), strongly reduced the RRDP-induced formation of IL-1beta at 1mug RRDP/ml (around 80 % inhibition), but had only marginal or no effects at higher RRDP-concentrations (10 and 100 mug /ml). In summary, all RRDP tested had a clear pyrogen effect in this in vitro model. Endotoxin on the particles but also other factors contributed to the pyrogenic effect. As opposed to the limulus amebocyte lysate (LAL) assay (which measures endotoxin alone), IPT measures a broad range of pyrogens that may be present on particulate matter. The IPT method thus affords a simple, sensitive and quantitative determination of the total pyrogenic potential of ambient particles.

  15. Pseudodementia and competency.

    Science.gov (United States)

    Good, M I

    1993-01-01

    An increase in the number of challenges to competency determinations in probate cases parallels an increasingly aging population. In the literature on competency determination, there is little if any discussion of the implications of pseudodementing conditions, which can quite readily be misdiagnosed as true dementias, especially in the elderly. This case report describes a patient thought to have had a stroke with dementia and paresis who turned out to have had a pseudodementia. She later made a dramatic and somewhat surprising recovery. It subsequently came to light that a nearly successful attempt had been made to defraud her of her estate during her presumed dementia, which was thought to have been irreversible. The case underscores issues in competency determination, including matters of diagnosis, prognosis, and undue influence.

  16. Language competence in movement

    DEFF Research Database (Denmark)

    Laursen, Helle Pia; Mogensen, Naja Dahlstrup

    2016-01-01

    multilingual children's language and literacy acquisition processes, we direct our focus to a single child's active exploration of what it means to know a language. Through analysis of interviews and researcher generated activities, we see how this child both describes and does language competence......This article examines how, in a multilingual perspective, language competence is experienced, talked about and practiced by language users themselves. By viewing children as active co-creators of the spaces in which language is used, this article contributes to a research tradition in which focus...... is shifted from viewing the individual's language competence as a mental linguistic or communicative property, to viewing language as a series of social and spatial practices. Looking at data from the research project Tegn på Sprog (in the following referred to as Signs of Language), which examines...

  17. Impact of lfuxapyroxad on the microbial community structure and functional diversity in the silty-loam soil

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-hu; XU Jun; LIU Yong-zhuo; DONG Feng-shou; LIU Xin-gang; ZHANG Wen-wen; ZHENG Yong-quan

    2015-01-01

    The aim of this work was to assess the effect of applying three different doses of lfuxapyroxad on microbial activity, com-munity structure and functional diversity as measured by respiration, microbial biomass C, phospholipid fatty acid (PLFA) and community-level physiological proifles (CLPPs). Our results demonstrated that substrate-induced respiration (on day 15) and microbial biomass C (on days 7 and 15) were inhibited by lfuxapyroxad, but stimulation was observed thereafter. In contrast, lfuxapyroxad addition increased the basal respiration and metabolic quotients (qCO2) and respiratory quotients (QR). Analysis of the PLFA proifles revealed that the total and bacterial biomass (both Gram-positive bacteria (GP) and Gram-negative bacteria (GN)) were decreased within the initial 15 days, whereas those as wel as the GN/GP ratio were increased at days 30 and 60. Fluxapyroxad input decreased the fungi biomass but increased the bacteria/fungi ratio at al incubation time. Moreover, high lfuxapyroxad input (75 mg lfuxapyroxad kg–1 soil dry weight) increased the microbial stress level. A principal component analysis (PCA) of the PLFAs revealed that lfuxapyroxad treatment signiifcantly shifted the microbial community structure, but al of the observed effects were transient. Biolog results showed that average wel color development (AWCD) and functional diversity index (H´) were increased only on day 60. In addition, the dissipation of lfuxa-pyroxad was slow in soil, and the degradation half-lives varied from 158 to 385 days depending on the concentration tested.

  18. Anoxic carbon degradation in Arctic sediments: Microbial transformations of complex substrates

    DEFF Research Database (Denmark)

    2005-01-01

    Complex substrates are degraded in anoxic sediments by the concerted activities of diverse microbial communities. To explore the effects of substrate complexity on carbon transformations in permanently cold anoxic sediments, four substrates—Spirulina cells, Isochrysis cells, and soluble high...... of carbon degradation diverged, with an additional 43%, 32%, 33%, and 8% of Isochrysis, Iso-Ex, Spirulina, and Spir-Ex carbon respired to CO2 over the next 750 h of incubation. Somewhat surprisingly, the soluble, carbohydrate-rich extracts did not prove to be more labile substrates than the whole cells from...... which they were derived. Although Spirulina and Iso-Ex differed in physical and chemical characteristics (solid/soluble, C/N ratio, lipid and carbohydrate content), nearly identical quantities of carbon were respired to CO2. In contrast, only 15% of Spir-Ex carbon was respired, despite the initial burst...

  19. Microbial control of arthropod-borne disease

    Science.gov (United States)

    Saldaña, Miguel A; Hegde, Shivanand; Hughes, Grant L

    2017-01-01

    Arthropods harbor a diverse array of microbes that profoundly influence many aspects of host biology, including vector competence. Additionally, symbionts can be engineered to produce molecules that inhibit pathogens. Due to their intimate association with the host, microbes have developed strategies that facilitate their transmission, either horizontally or vertically, to conspecifics. These attributes make microbes attractive agents for applied strategies to control arthropod-borne disease. Here we discuss the recent advances in microbial control approaches to reduce the burden of pathogens such as Zika, Dengue and Chikungunya viruses, and Trypanosome and Plasmodium parasites. We also highlight where further investigation is warranted. PMID:28177042

  20. Microbial control of arthropod-borne disease

    Directory of Open Access Journals (Sweden)

    Miguel A Saldaña

    Full Text Available Arthropods harbor a diverse array of microbes that profoundly influence many aspects of host biology, including vector competence. Additionally, symbionts can be engineered to produce molecules that inhibit pathogens. Due to their intimate association with the host, microbes have developed strategies that facilitate their transmission, either horizontally or vertically, to conspecifics. These attributes make microbes attractive agents for applied strategies to control arthropod-borne disease. Here we discuss the recent advances in microbial control approaches to reduce the burden of pathogens such as Zika, Dengue and Chikungunya viruses, and Trypanosome and Plasmodium parasites. We also highlight where further investigation is warranted.

  1. Respiration parameters determined by the ISO-17155 method as potential indicators of copper pollution in vineyard soils after long-term fungicide treatment.

    Science.gov (United States)

    Soler-Rovira, Pedro; Fernández-Calviño, David; Arias-Estévez, Manuel; Plaza, César; Polo, Alfredo

    2013-03-01

    This study seeks to determine the impact of copper-based fungicides on the respiration of vineyard soils. The ISO-17155 is an international standard recommended for monitoring soil quality by the evaluation of the effects of pollutants on soil microbial activity. Respiration curves and derived parameters [i.e., basal respiration (RB), substrate-induced respiration (RS), lag time (tlag), growth rate (μ), time to the peak maximum (tpeakmax), respiratory-activation quotient (QR), and the cumulative O2 consumption (CR)] were determined from 95 vineyard soils that covered a wide range of Cu contents. Statistical analyses showed that most of the variance of the ISO-17155 parameters was due to soil pH and organic C content, but not to the Cu pollution. When the parameters were expressed as a function of soil organic C content, the effect of soil Cu content was found to be significant on RS and tpeakmax but not on RB and CR. The results indicated that threshold values of total (CuT) and exchangeable (CuEX) contents indicative of soil Cu pollution cannot be established. However, adequate management practices resulting in soil organic C contents>2% and pH>5.5 are recommended for preserving vineyard soil quality.

  2. Assessment of microbial respiratory activity of a manufactured gas plant soil after remediation using sunflower oil.

    Science.gov (United States)

    Gong, Zongqiang; Alef, Kassem; Wilke, Berndt-Michael; Mai, Maike; Li, Peijun

    2005-09-30

    Microbial activity of a manufactured gas plant (MGP) soil, as well as remaining oil degradability, before and after remediation using sunflower oil was assessed. A sandy soil contaminated with polycyclic aromatic hydrocarbons (PAHs) was collected from an MGP site in Berlin, Germany. Column solubilizations of PAHs from the field-moist soil and air-dried soil using sunflower oil as an extractant at an oil/soil ratio of 2:1 (v/m) were carried out to compare PAH removals from the soil under these two conditions. After column solubilizations, portions of untreated soil (UTS), solubilized field-moist soil (SFMS), and solubilized air-dried soil (SADS) were amended with nutrients. Both nutrient amended and unamended soil samples were subjected to soil respiratory measurement. Soil respiration parameters, such as basal respiration rate, nutrient-induced respiration rate, lag time, exponential growth rate, respiratory activation quotient, peak maximum time, and cumulative CO2 evolution were calculated from the soil respiration curves. The parameters were compared using analysis of variance (ANOVA) and least-significance difference (LSD). Results showed that the impact of soil moisture on the PAH removals was quite significant, with the SADS showing higher PAH removals and the SFMS showing lower ones. There were significant differences between the respiration parameters with respect to the UTS, SFMS, and SADS. Basal respiration rate, nutrient-induced respiration rate, and exponential growth rate were lower for the SFMS and SADS relative to the UTS. Lag time and peak maximum time were higher for the SFMS and SADS relative to the UTS. Exponential growth rate was higher for the SFMS relative to the SADS. These parameters demonstrated that soil microbial activity was reduced at the onset of the test, because a lot of bioavailable materials for microbial growth were removed by sunflower oil. On the other hand, cumulative CO2 evolutions in the SFMS and SADS were higher than that in

  3. ETBE (ethyl tert butyl ether) and TAME (tert amyl methyl ether) affect microbial community structure and function in soils.

    Science.gov (United States)

    Bartling, Johanna; Esperschütz, Jürgen; Wilke, Berndt-Michael; Schloter, Michael

    2011-03-15

    Ethyl tert butyl ether (ETBE) and tert amyl methyl ether (TAME) are oxygenates used in gasoline in order to reduce emissions from vehicles. The present study investigated their impact on a soil microflora that never was exposed to any contamination before. Therefore, soil was artificially contaminated and incubated over 6 weeks. Substrate induced respiration (SIR) measurements and phospholipid fatty acid (PLFA) analysis indicated shifts in both, microbial function and structure during incubation. The results showed an activation of microbial respiration in the presence of ETBE and TAME, suggesting biodegradation by the microflora. Furthermore, PLFA concentrations decreased in the presence of ETBE and TAME and Gram-positive bacteria became more dominant in the microbial community.

  4. Respirable crystalline silica: Analysis methodologies; Silice cristalina respirable: Metodologias de analisis

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Tena, M. P.; Zumaquero, E.; Ibanez, M. J.; Machi, C.; Escric, A.

    2012-07-01

    This paper describes different analysis methodologies in occupational environments and raw materials. A review is presented of the existing methodologies, the approximations made, some of the constraints involved, as well as the best measurement options for the different raw materials. In addition, the different factors that might affect the precision and accuracy of the results are examined. With regard to the methodologies used for the quantitative analysis of any of the polymorph s, particularly of quartz, the study centres particularly on the analytical X-ray diffraction method. Simplified methods of calculation and experimental separation are evaluated for the estimation of this fraction in the raw materials, such as separation methods by centrifugation, sedimentation, and dust generation in controlled environments. In addition, a review is presented of the methodologies used for the collection of respirable crystalline silica in environmental dust. (Author)

  5. Identification of electrode respiring, hydrocarbonoclastic bacterial strain Stenotrophomonas maltophilia MK2 highlights the untapped potential for environmental bioremediation

    Directory of Open Access Journals (Sweden)

    Krishnaveni Venkidusamy

    2016-12-01

    Full Text Available Electrode respiring bacteria (ERB possess a great potential for many biotechnological applications such as microbial electrochemical remediation systems (MERS because of their exoelectrogenic capabilities to degrade xenobiotic pollutants. Very few ERB have been isolated from MERS, those exhibited a bioremediation potential towards organic contaminants. Here we report once such bacterial strain, Stenotrophomonas maltophilia MK2, a facultative anaerobic bacterium isolated from a hydrocarbon fed MERS, showed a potent hydrocarbonoclastic behavior under aerobic and anaerobic environments. Distinct properties of the strain MK2 were anaerobic fermentation of the amino acids, electrode respiration, anaerobic nitrate reduction and the ability to metabolize n-alkane components (C8-C36 of petroleum hydrocarbons including the biomarkers, pristine and phytane. The characteristic of diazoic dye decolorization was used as a criterion for pre-screening the possible electrochemically active microbial candidates. Bioelectricity generation with concomitant dye decolorization in MERS showed that the strain is electrochemically active. In acetate fed microbial fuel cells, maximum current density of 273±8 mA/m2 (1000Ω was produced (power density 113±7 mW/m2 by strain MK2 with a coulombic efficiency of 34.8 %. Further, the presence of possible alkane hydroxylase genes (alkB and rubA in the strain MK2 indicated that the genes involved in hydrocarbon degradation are of diverse origin. Such observations demonstrated the potential of facultative hydrocarbon degradation in contaminated environments. Identification of such a novel petrochemical hydrocarbon degrading ERB is likely to offer a new route to the sustainable bioremedial process of source zone contamination with simultaneous energy generation through MERS.

  6. Identification of Electrode Respiring, Hydrocarbonoclastic Bacterial Strain Stenotrophomonas maltophilia MK2 Highlights the Untapped Potential for Environmental Bioremediation

    Science.gov (United States)

    Venkidusamy, Krishnaveni; Megharaj, Mallavarapu

    2016-01-01

    Electrode respiring bacteria (ERB) possess a great potential for many biotechnological applications such as microbial electrochemical remediation systems (MERS) because of their exoelectrogenic capabilities to degrade xenobiotic pollutants. Very few ERB have been isolated from MERS, those exhibited a bioremediation potential toward organic contaminants. Here we report once such bacterial strain, Stenotrophomonas maltophilia MK2, a facultative anaerobic bacterium isolated from a hydrocarbon fed MERS, showed a potent hydrocarbonoclastic behavior under aerobic and anaerobic environments. Distinct properties of the strain MK2 were anaerobic fermentation of the amino acids, electrode respiration, anaerobic nitrate reduction and the ability to metabolize n-alkane components (C8–C36) of petroleum hydrocarbons (PH) including the biomarkers, pristine and phytane. The characteristic of diazoic dye decolorization was used as a criterion for pre-screening the possible electrochemically active microbial candidates. Bioelectricity generation with concomitant dye decolorization in MERS showed that the strain is electrochemically active. In acetate fed microbial fuel cells (MFCs), maximum current density of 273 ± 8 mA/m2 (1000 Ω) was produced (power density 113 ± 7 mW/m2) by strain MK2 with a coulombic efficiency of 34.8%. Further, the presence of possible alkane hydroxylase genes (alkB and rubA) in the strain MK2 indicated that the genes involved in hydrocarbon degradation are of diverse origin. Such observations demonstrated the potential of facultative hydrocarbon degradation in contaminated environments. Identification of such a novel petrochemical hydrocarbon degrading ERB is likely to offer a new route to the sustainable bioremedial process of source zone contamination with simultaneous energy generation through MERS. PMID:28018304

  7. Automatic respiration tracking for radiotherapy using optical 3D camera

    Science.gov (United States)

    Li, Tuotuo; Geng, Jason; Li, Shidong

    2013-03-01

    Rapid optical three-dimensional (O3D) imaging systems provide accurate digitized 3D surface data in real-time, with no patient contact nor radiation. The accurate 3D surface images offer crucial information in image-guided radiation therapy (IGRT) treatments for accurate patient repositioning and respiration management. However, applications of O3D imaging techniques to image-guided radiotherapy have been clinically challenged by body deformation, pathological and anatomical variations among individual patients, extremely high dimensionality of the 3D surface data, and irregular respiration motion. In existing clinical radiation therapy (RT) procedures target displacements are caused by (1) inter-fractional anatomy changes due to weight, swell, food/water intake; (2) intra-fractional variations from anatomy changes within any treatment session due to voluntary/involuntary physiologic processes (e.g. respiration, muscle relaxation); (3) patient setup misalignment in daily reposition due to user errors; and (4) changes of marker or positioning device, etc. Presently, viable solution is lacking for in-vivo tracking of target motion and anatomy changes during the beam-on time without exposing patient with additional ionized radiation or high magnet field. Current O3D-guided radiotherapy systems relay on selected points or areas in the 3D surface to track surface motion. The configuration of the marks or areas may change with time that makes it inconsistent in quantifying and interpreting the respiration patterns. To meet the challenge of performing real-time respiration tracking using O3D imaging technology in IGRT, we propose a new approach to automatic respiration motion analysis based on linear dimensionality reduction technique based on PCA (principle component analysis). Optical 3D image sequence is decomposed with principle component analysis into a limited number of independent (orthogonal) motion patterns (a low dimension eigen-space span by eigen-vectors). New

  8. Bundvands respiration i Kattegat og Bælthavet

    DEFF Research Database (Denmark)

    Hansen, Jørgen L. S.; Bendtsen, Jørgen

    Der findes generelt meget få direkte målinger af den pelagiske respiration, og det har ikke været muligt at finde repræsentative målinger af den pelagiske respiration for de åbne danske farvande. Her præsenteres et sæsonstudie af bundvandets respiration fra 5 stationer i et transekt gående fra det....... Temperaturfølsomheden af respirationsraten udtrykt som en Q10 var 3,01 ± 1.07 for alle forsøg og uafhængigt af om prøverne blev kølet eller opvarmet under inkubationerne. Den labile pulje af organisk stof blev bestemt og de observerede respirations rater svarede til specifikke kulstof omsætningsrater på mellem 0...... målbar reduktion i det partikulære materiale under inkubationerne, tyder overraskende på,at opløst organisk materiale (DOM) er den vigtigste kulstofkilde for bundvandet respiration....

  9. Assessment of respiration activity and ecotoxicity of composts containing biopolymers.

    Science.gov (United States)

    Kopeć, Michał; Gondek, Krzysztof; Baran, Agnieszka

    2013-03-01

    The research was conducted to determine if introducing biodegradable polymer materials to the composting process would affect selected biological properties of mature compost. Determination of biological properties of composts composed of testing their respiration activity and toxicity. Respiration activity was measured in material from the composting process by means of OxiTop Control measuring system. The ecotoxicity of composts was estimated by means of a set of biotests composed of three microbiotests using five test organisms. Introduction of polymer materials caused a decrease in respiration activity of mature compost. Similar dependencies as in the case of mass loss were registered. Compost to which a biodegradable polymer with the highest content of starch was added revealed the smallest difference in comparison with organic material composted without polymers. Lower content of starch in a polymer caused lower respiration activity of composts, whereas microorganism vaccine might have accelerated maturing of composts, thus contributing to the smallest respiration of compost. In composts containing biopolymers the following were observed: an increase in germination inhibition--2.5 times, roots growth inhibition--1.8 times, growth inhibition of Heterocypris incongruens--four times and luminescence inhibition of Vibrio fischeri--1.6 times in comparison with the control (compost K1). Composts containing biopolymers were classified as toxicity class III, whereas the compost without polymer addition as class II.

  10. Cannabinoid-induced changes in respiration of brain mitochondria.

    Science.gov (United States)

    Fišar, Zdeněk; Singh, Namrata; Hroudová, Jana

    2014-11-18

    Cannabinoids exert various biological effects that are either receptor-mediated or independent of receptor signaling. Mitochondrial effects of cannabinoids were interpreted either as non-receptor-mediated alteration of mitochondrial membranes, or as indirect consequences of activation of plasma membrane type 1 cannabinoid receptors (CB1). Recently, CB1 receptors were confirmed to be localized to the membranes of neuronal mitochondria, where their activation directly regulates respiration and energy production. Here, we performed in-depth analysis of cannabinoid-induced changes of mitochondrial respiration using both an antagonist/inverse agonist of CB1 receptors, AM251 and the cannabinoid receptor agonists, Δ(9)-tetrahydrocannabinol (THC), cannabidiol, anandamide, and WIN 55,212-2. Relationships were determined between cannabinoid concentration and respiratory rate driven by substrates of complex I, II or IV in pig brain mitochondria. Either full or partial inhibition of respiratory rate was found for the tested drugs, with an IC50 in the micromolar range, which verified the significant role of non-receptor-mediated mechanism in inhibiting mitochondrial respiration. Effect of stepwise application of THC and AM251 evidenced protective role of AM251 and corroborated the participation of CB1 receptor activation in the inhibition of mitochondrial respiration. We proposed a model, which includes both receptor- and non-receptor-mediated mechanisms of cannabinoid action on mitochondrial respiration. This model explains both the inhibitory effect of cannabinoids and the protective effect of the CB1 receptor inverse agonist.

  11. Exposure to inhalable, respirable, and ultrafine particles in welding fume.

    Science.gov (United States)

    Lehnert, Martin; Pesch, Beate; Lotz, Anne; Pelzer, Johannes; Kendzia, Benjamin; Gawrych, Katarzyna; Heinze, Evelyn; Van Gelder, Rainer; Punkenburg, Ewald; Weiss, Tobias; Mattenklott, Markus; Hahn, Jens-Uwe; Möhlmann, Carsten; Berges, Markus; Hartwig, Andrea; Brüning, Thomas

    2012-07-01

    This investigation aims to explore determinants of exposure to particle size-specific welding fume. Area sampling of ultrafine particles (UFP) was performed at 33 worksites in parallel with the collection of respirable particles. Personal sampling of respirable and inhalable particles was carried out in the breathing zone of 241 welders. Median mass concentrations were 2.48 mg m(-3) for inhalable and 1.29 mg m(-3) for respirable particles when excluding 26 users of powered air-purifying respirators (PAPRs). Mass concentrations were highest when flux-cored arc welding (FCAW) with gas was applied (median of inhalable particles: 11.6 mg m(-3)). Measurements of particles were frequently below the limit of detection (LOD), especially inside PAPRs or during tungsten inert gas welding (TIG). However, TIG generated a high number of small particles, including UFP. We imputed measurements welding fume. Concentrations were mainly predicted by the welding process and were significantly higher when local exhaust ventilation (LEV) was inefficient or when welding was performed in confined spaces. Substitution of high-emission techniques like FCAW, efficient LEV, and using PAPRs where applicable can reduce exposure to welding fume. However, harmonizing the different exposure metrics for UFP (as particle counts) and for the respirable or inhalable fraction of the welding fume (expressed as their mass) remains challenging.

  12. Glycolysis-respiration relationships in a neuroblastoma cell line.

    Science.gov (United States)

    Swerdlow, Russell H; E, Lezi; Aires, Daniel; Lu, Jianghua

    2013-04-01

    Although some reciprocal glycolysis-respiration relationships are well recognized, the relationship between reduced glycolysis flux and mitochondrial respiration has not been critically characterized. We concomitantly measured the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) of SH-SY5Y neuroblastoma cells under free and restricted glycolysis flux conditions. Under conditions of fixed energy demand ECAR and OCR values showed a reciprocal relationship. In addition to observing an expected Crabtree effect in which increasing glucose availability raised the ECAR and reduced the OCR, a novel reciprocal relationship was documented in which reducing the ECAR via glucose deprivation or glycolysis inhibition increased the OCR. Substituting galactose for glucose, which reduces net glycolysis ATP yield without blocking glycolysis flux, similarly reduced the ECAR and increased the OCR. We further determined how reduced ECAR conditions affect proteins that associate with energy sensing and energy response pathways. ERK phosphorylation, SIRT1, and HIF1a decreased while AKT, p38, and AMPK phosphorylation increased. These data document a novel intracellular glycolysis-respiration effect in which restricting glycolysis flux increases mitochondrial respiration. Since this effect can be used to manipulate cell bioenergetic infrastructures, this particular glycolysis-respiration effect can practically inform the development of new mitochondrial medicine approaches. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Breathing simulator of workers for respirator performance test.

    Science.gov (United States)

    Yuasa, Hisashi; Kumita, Mikio; Honda, Takeshi; Kimura, Kazushi; Nozaki, Kosuke; Emi, Hitoshi; Otani, Yoshio

    2015-01-01

    Breathing machines are widely used to evaluate respirator performance but they are capable of generating only limited air flow patterns, such as, sine, triangular and square waves. In order to evaluate the respirator performance in practical use, it is desirable to test the respirator using the actual breathing patterns of wearers. However, it has been a difficult task for a breathing machine to generate such complicated flow patterns, since the human respiratory volume changes depending on the human activities and workload. In this study, we have developed an electromechanical breathing simulator and a respiration sampling device to record and reproduce worker's respiration. It is capable of generating various flow patterns by inputting breathing pattern signals recorded by a computer, as well as the fixed air flow patterns. The device is equipped with a self-control program to compensate the difference in inhalation and exhalation volume and the measurement errors on the breathing flow rate. The system was successfully applied to record the breathing patterns of workers engaging in welding and reproduced the breathing patterns.

  14. Electrokinetic remediation and microbial community shift of β-cyclodextrin-dissolved petroleum hydrocarbon-contaminated soil.

    Science.gov (United States)

    Wan, Chunli; Du, Maoan; Lee, Duu-Jong; Yang, Xue; Ma, Wencheng; Zheng, Lina

    2011-03-01

    Electrokinetic (EK) migration of β-cyclodextrin (β-CD), which is inclusive of total petroleum hydrocarbon (TPH), is an economically beneficial and environmentally friendly remediation process for oil-contaminated soils. Remediation studies of oil-contaminated soils generally prepared samples using particular TPHs. This study investigates the removal of TPHs from, and electromigration of microbial cells in field samples via EK remediation. Both TPH content and soil respiration declined after the EK remediation process. The strains in the original soil sample included Bacillus sp., Sporosarcina sp., Beta proteobacterium, Streptomyces sp., Pontibacter sp., Azorhizobium sp., Taxeobacter sp., and Williamsia sp. Electromigration of microbial cells reduced the biodiversity of the microbial community in soil following EK remediation. At 200 V m(-1) for 10 days, 36% TPH was removed, with a small population of microbial cells flushed out, demonstrating that EK remediation is effective for the present oil-contaminated soils collected in field.

  15. MICROBIAL FUEL CELL

    DEFF Research Database (Denmark)

    2008-01-01

    A novel microbial fuel cell construction for the generation of electrical energy. The microbial fuel cell comprises: (i) an anode electrode, (ii) a cathode chamber, said cathode chamber comprising an in let through which an influent enters the cathode chamber, an outlet through which an effluent...

  16. Biofilms: A microbial home

    Science.gov (United States)

    Chandki, Rita; Banthia, Priyank; Banthia, Ruchi

    2011-01-01

    Microbial biofilms are mainly implicated in etiopathogenesis of caries and periodontal disease. Owing to its properties, these pose great challenges. Continuous and regular disruption of these biofilms is imperative for prevention and management of oral diseases. This essay provides a detailed insight into properties, mechanisms of etiopathogenesis, detection and removal of these microbial biofilms. PMID:21976832

  17. Biofilms: A microbial home

    OpenAIRE

    Chandki, Rita; Banthia, Priyank; Banthia, Ruchi

    2011-01-01

    Microbial biofilms are mainly implicated in etiopathogenesis of caries and periodontal disease. Owing to its properties, these pose great challenges. Continuous and regular disruption of these biofilms is imperative for prevention and management of oral diseases. This essay provides a detailed insight into properties, mechanisms of etiopathogenesis, detection and removal of these microbial biofilms.

  18. Competencies in Teaching English.

    Science.gov (United States)

    Purves, Alan C.

    This paper discusses suggested requirements for a competency-based English teacher training program on the high school or college level. The author argues that an English teacher needs to demonstrate a basic knowledge of the subject matter in three areas: the structure and history of the English language, rhetorical theory and practice, and…

  19. Assessing cataract surgical competency

    NARCIS (Netherlands)

    Lee, Andrew G.; Greenlee, Emily; Oetting, Thomas A.; Beaver, Hilary A.; Johnson, A. Tim; Boldt, H. Culver; Abramoff, Michael; Olson, Richard; Carter, Keith

    2007-01-01

    The Accreditation Council for Graduate Medical Education has mandated that all residency training programs teach and assess 6 general competencies.1 A.G. Lee and K.D. Carter, Managing the new mandate in resident education: A blueprint for translating a national mandate into local compliance, Ophthal

  20. Competing Auctions of Skills

    DEFF Research Database (Denmark)

    Kennes, John; le Maire, Christian Daniel

    The model of competing sellers McAfee (1993) is applied to a labor market environment with heterogeneous workers, who differ by outside option and skill type, and heterogeneous firms, who differ by the amount of output produced when matched to each possible worker tyoe. We derive both a static...

  1. Competing Auctions of Skills

    DEFF Research Database (Denmark)

    Kennes, John; le Maire, Daniel

    We generalize McAfee’s (1993) game of competing sellers to the case of heterogeneous sellers. In the generalized McAfee (GM) game, the equilibrium expected job offer distribution of each worker (seller) type evolves over time as a function of stochastic events. We derive a tractable method of sol...

  2. Classical competing risks

    CERN Document Server

    Crowder, Martin J

    2001-01-01

    If something can fail, it can often fail in one of several ways and sometimes in more than one way at a time. There is always some cause of failure, and almost always, more than one possible cause. In one sense, then, survival analysis is a lost cause. The methods of Competing Risks have often been neglected in the survival analysis literature. Written by a leading statistician, Classical Competing Risks thoroughly examines the probability framework and statistical analysis of data of Competing Risks. The author explores both the theory of the subject and the practicalities of fitting the models to data. In a coherent, self-contained, and sequential account, the treatment moves from the bare bones of the Competing Risks setup and the associated likelihood functions through survival analysis using hazard functions. It examines discrete failure times and the difficulties of identifiability, and concludes with an introduction to the counting-process approach and the associated martingale theory.With a dearth of ...

  3. Competing Auctions of Skills

    DEFF Research Database (Denmark)

    Kennes, John; le Maire, Christian Daniel

    The model of competing sellers McAfee (1993) is applied to a labor market environment with heterogeneous workers, who differ by outside option and skill type, and heterogeneous firms, who differ by the amount of output produced when matched to each possible worker tyoe. We derive both a static...

  4. Supporting Lifelong Competence Development

    NARCIS (Netherlands)

    Koper, Rob

    2007-01-01

    The slides of a keynote for the EFODL conference about Demonstrating Transformation in Learning: Practice, Process and Product. 23rd & 24th May 2007, Belfast (http://efodl.belfastinstitute.ac.uk/). It introduces the core concepts of TENCompetence: Learning Networks, Personal Competence Management, P

  5. Competence development in UAS

    DEFF Research Database (Denmark)

    Thorslund, Jørgen; Brodersen, Anne Mygind

    2011-01-01

    As a University of Applied Science (UAS) University College Lillebaelt in Denmark is addressing education, knowledge production and professional development in perspective of life-long and life-wide learning. It is our basic assumption that that internal competence development ? individually...

  6. Competency in the Cockpit.

    Science.gov (United States)

    Brown, H. M.

    1992-01-01

    Examines how modern technology is redefining competences, particularly those required by aircrews in state-of-the-art cockpits and how rule-based descriptions may not always be as practical as cognitive schemas and frames or case-based reasoning. Concludes that a wider systems perspective must include a balance between intuitive and analytic…

  7. Calibrating Communication Competencies

    Science.gov (United States)

    Surges Tatum, Donna

    2016-11-01

    The Many-faceted Rasch measurement model is used in the creation of a diagnostic instrument by which communication competencies can be calibrated, the severity of observers/raters can be determined, the ability of speakers measured, and comparisons made between various groups.

  8. Pragmatics and Communicative Competences

    Science.gov (United States)

    Lin, Grace Hui Chin; Su, Simon Chun Feng; Ho, Max Ming Hsuang

    2009-01-01

    Pragmatics is included in one of four communicative competences (Canale, 1980). It is necessary and important to teach pragmatics at school in our globalized world in order to avoid as much as misunderstanding, which is likely to stem from cultural difference. As a result, greater importance should be attached to diverse customs and pragmatics.…

  9. Assessing cataract surgical competency

    NARCIS (Netherlands)

    Lee, Andrew G.; Greenlee, Emily; Oetting, Thomas A.; Beaver, Hilary A.; Johnson, A. Tim; Boldt, H. Culver; Abramoff, Michael; Olson, Richard; Carter, Keith

    2007-01-01

    The Accreditation Council for Graduate Medical Education has mandated that all residency training programs teach and assess 6 general competencies.1 A.G. Lee and K.D. Carter, Managing the new mandate in resident education: A blueprint for translating a national mandate into local compliance,

  10. Adult educators' core competences

    Science.gov (United States)

    Wahlgren, Bjarne

    2016-06-01

    Which competences do professional adult educators need? This research note discusses the topic from a comparative perspective, finding that adult educators' required competences are wide-ranging, heterogeneous and complex. They are subject to context in terms of national and cultural environment as well as the kind of adult education concerned (e.g. basic education, work-related education etc.). However, it seems that it is possible to identify certain competence requirements which transcend national, cultural and functional boundaries. This research note summarises these common or "core" requirements, organising them into four thematic subcategories: (1) communicating subject knowledge; (2) taking students' prior learning into account; (3) supporting a learning environment; and (4) the adult educator's reflection on his or her own performance. At the end of his analysis of different competence profiles, the author notes that adult educators' ability to train adult learners in a way which then enables them to apply and use what they have learned in practice (thus performing knowledge transfer) still seems to be overlooked.

  11. Assessment of Clinical Competence.

    Science.gov (United States)

    Newble, David I.

    1979-01-01

    Reviews current approaches to the examination of medical students' clinical competence, mentioning differences in approaches adopted in Australia, Great Britain, and North America. Test methods used in examination are discussed critically and their separate strengths and weaknesses are highlighted. Newer approaches involving multiple methods and…

  12. Assessing cataract surgical competency

    NARCIS (Netherlands)

    Lee, Andrew G.; Greenlee, Emily; Oetting, Thomas A.; Beaver, Hilary A.; Johnson, A. Tim; Boldt, H. Culver; Abramoff, Michael; Olson, Richard; Carter, Keith

    2007-01-01

    The Accreditation Council for Graduate Medical Education has mandated that all residency training programs teach and assess 6 general competencies.1 A.G. Lee and K.D. Carter, Managing the new mandate in resident education: A blueprint for translating a national mandate into local compliance, Ophthal

  13. Connecting Competing Memories

    NARCIS (Netherlands)

    Laarse, van der R.; Saloul, I.A.M.

    Research Expert Meeting: Connecting Competing Memories of War in Contemporary Europe5 March 2014NIAS hosts, 6 - 7 March, the expert meeting of the Consortium for 'The Cultural Heritage of War in Contemporary Europe'. The aim is to draft main themes and discuss financial and research structures regar

  14. Competence, governance, and entrepreneurship

    DEFF Research Database (Denmark)

    Foss, Nicolai Juul; Mahnke, Volker

    This title illustrates modern economics. Because it informs strategic choices, it is relevant to business administration in general, and for strategic management in particular. Two dominant streams may be identified in the literature, namely the "competence" and "governance" perspectives on the f......, and entrepreneurship to advance and stimulate economic strategy research....

  15. Competences of IT Architects

    NARCIS (Netherlands)

    Wieringa, Roel; Eck, van Pascal; Steghuis, Claudia; Proper, Erik

    2009-01-01

    The field of architecture in the digital world uses a plethora of terms to refer to different kinds of architects, and recognises a confusing variety of competences that these architects are required to have. Different service providers use different terms for similar architects and even if they use

  16. Strategic Leader Competencies

    Science.gov (United States)

    1992-05-08

    competencies in line with his "visionary leadership theory." His concept draws extensively from sound, quantitative research and social learning theory . A key...means for constructing social systems B. SELF-EFFICACY - STRONG SENSE OF INTERNAL CONTROL OR DIRECTION - (from social learning theory - a requisite

  17. Competence Enhancement Behavior Management

    Science.gov (United States)

    Farmer, Thomas W.; Goforth, Jennifer B.; Hives, Jacqueline; Aaron, Annie; Jackson, Frances; Sgammato, Adrienne

    2006-01-01

    Competence Enhancement Behavior Management is presented as a framework for supporting students with challenging behaviors in general education classrooms. This approach emphasizes classroom management and discipline strategies that (a) help to build positive relations with students, (b) communicate to students that they are important, and (c)…

  18. Competencies: requirements and acquisition

    NARCIS (Netherlands)

    Kuenn, A.C.; Meng, C.M.; Peters, Z.; Verhagen, A.M.C.

    2013-01-01

    Higher education is given the key task to prepare the highly talented among the young to fulfil highly qualified roles in the labour market. Successful labour market performance of graduates is generally associated with the acquisition of the correct competencies. Education as an individual investme

  19. Evolution of subsidiary competences

    DEFF Research Database (Denmark)

    Geisler Asmussen, Christian; Pedersen, Torben; Dhanaraj, Charles

    of competitive advantage of nations, we hypothesize the contingencies under which heterogeneity in host environments influences subsidiary competence configuration. We test our model with data from more than 2,000 subsidiaries in seven Western European countries. Our results provide new insights on the evolution...

  20. Evolution of subsidiary competences

    DEFF Research Database (Denmark)

    Geisler Asmussen, Christian; Pedersen, Torben; Dhanaraj, Charles

    of competitive advantage of nations, we hypothesize the contingencies under which heterogeneity in host environments influences subsidiary competence configuration. We test our model with data from more than 2,000 subsidiaries in seven Western European countries. Our results provide new insights on the evolution...